WO2004083381A2

WO2004083381A2 - Fibroblast growth factor receptor-1 polynucleotides, polypeptides, and mutants

Info

Publication number: WO2004083381A2
Application number: PCT/US2004/007220
Authority: WO
Inventors: Michael J. Econs; Kenneth E. White
Original assignee: Indiana University Advanced Research & Technology Institute
Priority date: 2003-03-13
Filing date: 2004-03-10
Publication date: 2004-09-30
Also published as: WO2004083381A3

Abstract

The invention relates to novel fibroblast growth factor receptor-1 polynucleotides and polypeptides, and to compositions, uses and methods thereof. Further, this invention relates to agonists and antagonists of fibroblast growth factor receptor-1 polypeptides, as well as to methods of treatment of disorders arising from altered fibroblast growth factor receptor-1 polynucleotides and polypeptides.

Description

TITLE OF THE INVENTION Fibroblast Growth Factor Receptor-1 Polynucleotides, Polypeptides, and Mutants

BACKGROUND OF THE INVENTION

Classically, all fibroblast growth factors (FGF) signal through one or more members of the fibroblast growth factor receptor (FGFR) family. This receptor family consists of four well-characterized members, FGFR1, FGFR2, FGFR3, and FGFR4, as well as the novel receptor FGFR5 (Kim et al., 2001, Biochimica et Biophysica Acta 1518:152-156) and, in concert with the large family of fibroblast growth factors (FGFs), are necessary for proper embryonic development (for extensive reviews see Ornitz and Itoh, 2001, Genome Biology 2(3):3005.1-3005.12; Ornitz and Marie, 2002, Genes & Development, 16:1446-1465; Wilkie et al, 2002, American Journal of Medical Genetics 112(3):266-78; Powers et al., 2000, Endocrine-Related Cancer 7:165-197; Johnson and Williams, 1999, Advances in Cancer Research 60:1-41). The FGFRs share similar gene exon-intron arrangements, and are generally characterized by three extracellular immunoglobulin (Ig)-like domains, a single transmembrane domain, followed by an intracellular split tyrosine kinase domain. One exception to this structure is FGFR5, which has all the other features of an FGFR, but does not contain a transmembrane domain and may function as a "decoy receptor" (Kim et al., 2001, Biochimica et Biophysica Acta 1518:152- 156; Sleeman et al., 2001, Gene 271(2).T71-82). Previous work demonstrated that the FGFRs are receptor tyrosine kinases that dimerize upon FGF binding in a heparin- dependent manner (Ornitz et al, 1992, Molecular and Cellular Biology 12:240-247; Rapraeger et al., 1991, Science 252: 1705-1708). Ligand binding largely occurs in Ig- like domains II and III, and specificity of the FGFs for their cognate FGFRs can be controlled by alternative splicing. Within Ig-like domain III of FGFR1-3, either of two mutually exclusive exons can be inserted to produce "Hlb" or "IIIc" receptor isoforms (the "a" isoforms of FGFR1-3 do not contain transmembrane domains and are thought to be "decoy" receptors). X-ray crystallographic studies indicate that the FGF-FGFR complex is a heteropentamer consisting of two FGFRs, two FGFs, and a hep^'afiή prdteoglycan molecule (Plotnikov et al, 2000, Cell 101:413-424; Pellegrini et al., 2000, Nature 407:1029-1034). Stabilization of this complex leads to autophosphorylation of critical FGFR tyrosine residues, followed by binding or activation of initial signaling proteins (Klint and Claesson- Welsh, 1999, Frontiers in Bioscience 4:D165-177).

Proper expressional timing and localization of the FGFRs in concert with the FGFs is responsible for directing bone formation by regulating chondrogenesis (Frenkel et al, 1992, Acta Anat. 145(3):265-8), growth plate hypertrophy, and endochondral bone ossification. This is most clearly exemplified by the fact that dominantly-inherited mutations in the FGFRs -1, -2, and -3 are responsible for a genetically diverse group of human skeletal disorders (Shiang et al., 1994, Cell 78:335-342; Muenke et al, 1994, Nature Genetics 8:269-274; Reardon et al, 1994, Nat. Genet. 8(1):98-103; Webster and Donoghue, 1997, Trends Genet. 13(5): 178-82). These disorders can be generally characterized into two groups: the craniosynostosis syndromes and the dwarfing syndromes (Ornitz and Marie, 2002, Genes & Development, 16:1446-1465; Kannan and Givol, 2000, IUBMB Life 49(3): 197-205). The craniosynostosis syndromes, caused primarily by mutations in FGFRl and FGFR2, arise from the early fusion of cranial sutures as a result of inappropriate receptor signaling, and include Pfeiffer, Crouzon, Apert, and Jackson- Weiss syndromes. The dwarfing syndromes, such as achondroplasia, hypochondroplasia, and thanatophoric dysplasia types 1 & 2, are caused by dominant, activating mutations in FGFR3, which lead to premature closure of the long bone growth plates. Several of the above disorders are the result of pleiotropic mutations, in that distinct FGFR3 mutations have been associated with Crouzon syndrome with acanthosis nigricans (Meyers et al., 1995, Nature Genetics 11 :462-464), and FGFRl mutations are associated with both Pfeiffer and Jackson- Weiss syndromes.

The mutations in FGFRs -1, -2, and -3 are generally missense and insertional changes in DNA. When expressed in vitro, it was determined that these substitutions are considered gain-of-function because the mutations result in FGFR residue alterations that lead to inappropriate receptor signaling through ligand- independent or -dependent dimerization, altered affinity for FGF binding, mis-

l-PH/1977697 1 9 expression oi receptor spnce variants during embryonic development, and direct activation of the FGFR tyrosine kinase domains. The mutations are dominant, and are usually the result of a de novo mutation.

Conditions in which serum phosphate levels are reduced or elevated, referred to as hypophosphatemia and hyperphosphatemia, respectively, are associated with a large and diverse group of clinically significant diseases. Hypophosphatemia, which often results from renal phosphate wasting, is caused by a number of genetic disorders including X-linked hypophosphatemic rickets (XLH), hereditary hypophosphatemic rickets with hypercalciuria (HHRH), hypophosphatemic bone disease (HBD), and autosomal dominant hypopohsphatemic rickets (ADHR). Non- genetic causes of hypophosphatemia include tumor induced osteomalacia, fibrous dysplasia, and linear sebaceous nevus syndrome. Hyperphosphatemia, observed in patients with mild renal insufficiency and tumoral calcinosis, can often be associated with soft tissue calcification, secondary hyperparathyroidism, tertiary hyperparathyroidism, and other metabolic derangements.

Studies involving murine transgenic and knock out models demonstrated that FGF2 (Montero et al., 2000, The Journal of Clinical Investigation 105(8):1085-1093; Coffin et al, 1995, Molecular Biology of the Cell 6:1861-1873), FGF8 (Meyers et al., 1998, Nature Genetics 18:136-141), and FGF10 (Min et al., 1998, Genes and Development 12(20):3156-3161; Sekine et al., 1999, Nature

Genetics 21:138-141), are critical for skeletal and limb development. However, it has become clear that the FGFs and FGFRs have physiological roles in addition to development and differentiation. Autosomal dominant hypophosphatemic rickets (ADHR) is a renal phosphate wasting disorder characterized by short stature, bone pain, fracture, and lower extremity deformity (Bianchine et al., 1971, Birth Defects: Original Article Series 7:287-295; Econs and McEnery, 1997, Journal of Clinical Endocrinology and Metabolism 82:674-681). The gene causing ADHR, FGF23, which encodes a secreted FGF family member, was recently identified and is the subject of U.S. Patent Application No. 09/901,938, incorporated in its entirety herein by reference. ADHR kindreds have FGF23 missense mutations that lead to replacement of either of two critical arginine residues within a minimum furin protease site (White et al., 2000, Nature Genetics 26:345-348). Transient expression

l-PH/ 1977697.1 7 oi tne mutant proteins demonstrated tiiat the ADLL substitutions stabilize the full length FGF-23 protein in vitro (White et al, 2001, Kidney International 60(6):2079- 2086; Shimada et al, 2002, Endocrinology 143:3179-3182). Injection of animals with either recombinant wild-type or mutant FGF-23 results in renal phosphate wasting and osteomalacia (Shimada et al., 2002, Endocrinology 143:3179-3182), indicating that FGF-23 is a phosphaturic factor. Previous investigation also demonstrated that FGF-23 is overexpressed in tumors that cause tumor induced osteomalacia (TIO), an acquired disorder of renal phosphate wasting often associated with tumors of mesenchymal origin (White et al., 2001, Journal of Clinical Endocrinology and Metabolism 86(2):497-500; Shimada et al., 2001, Proceedings of the National Academy of Sciences 98:6494-6499). Patients with TIO share biochemical and clinical profiles with ADHR patients including hypophosphatemia, low or inappropriately normal serum 1,25 (OH)₂ vitamin D concentrations, osteomalacia, and reduced tubular reabsorption of phosphate/unit glomerular filtration rate (TMP/GFR) (Econs and McEnery, 1997, Journal of Clinical Endocrinology and Metabolism 82:674-681; Tenenhouse and Econs, Mendelian Hypophosphatemias, in The Metabolic and Molecular Basis of Inherited Disease, C.R. Scriver, Editor. 1998, McGraw-Hill: New York; Sweet et al., 1980, Annals of Internal Medicine 93(2):279- 280), suggesting that FGF-23 may be the common denominator underlying the pathophysiology of the two disorders. Serum assays specific for FGF-23 indicate that circulating FGF-23 concentrations are elevated in TIO patients as well as in X-linked hypophosphatemic rickets (XLH) patients (Yamazaki et al., 2002, J. Clin. Endocrinol. Metab. 87(11):4957-60), which have clinical and laboratory similarities to ADHR patients (Tenenhouse and Econs, Mendelian Hypophosphatemias, in The Metabolic and Molecular Basis of Inherited Disease, C.R. Scriver, Editor. 1998, McGraw-Hill: New York). Interestingly, the FGF-23 knock-out mouse is hyperphosphatemic (Kakitani et al., 2002, Journal of Bone and Mineral Research 17(S1): p. SI 68), demonstrating that FGF-23 may have roles beyond rare phosphate wasting disorders, and may be required for maintaining normophosphatemia. The molecular mechanisms by which proper serum phosphate concentrations are maintained are poorly understood. Identification of genes responsible for inherited disorders involving disturbances in phosphate homeostasis

l-PH/l 977697.1 A may provide insight into the pathways that regulate phosphate balance. Currently, despite clinical features apparent in patients with hypophosphatemic and hyperphosphatemic conditions, molecular markers useful in early diagnosis, grading, and staging of these disorders are scarce. Likewise, the current lack of effective methods of treatment for patients with hypophosphatemic and hyperphosphatemic disorders presents a need for alternative therapies. The present invention fulfills these needs.

BRIEF SUMMARY OF THE INVENTION

The invention features a method of treating a phosphate homeostasis disorder in a mammal, whereby the method comprises administering to a mammal afflicted with a phosphate homeostasis disorder a therapeutically effective amount of an FGFRl agonist, thereby alleviating the disorder in the mammal. In an aspect of the invention, the mammal is a human.

A phosphate homeostasis disorder of the invention may be selected from the group consisting of craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia.

In an embodiment of the invention, an agonist for treating a phosphate disorder in a mammal enhances FGFR1-FGF23 binding. In one aspect of the invention, such an agonist binds to FGFRl . In another aspect of the invention, such an agonist binds to FGF23. In yet another aspect of the invention, such an agonist binds to both FGFRl and FGF23. In still another aspect of the invention, such an agonist has the properties of binding to FGFRl and FGF23, and may or may not bind to both FGFRl and FGF23 at the same time. Agonists encompassed by the presnt invention include a peptide, a protein, a small organic molecule, a large organic molecule, a carbohydrate, and a lipid. The present invention features a method of treating a hypophosphatemic disorder in a mammal, wherein the method comprises administering to a mammal afflicted with a hypophosphatemic disorder a

l-PH/1977697.1 ς therapeutically effective amount of a soluble form of FGFRl, whereby the soluble form of FGFRl functions as a competitive antagonist of FGFRl, thereby alleviating the disorder in the mammal. In an aspect of the invention, the mammal is a human. The present invention features a method of treating a hypophosphatemic disorder in a mammal, wherein the method comprises administering to a mammal afflicted with a hypophosphatemic disorder a therapeutically effective amount of a soluble form of Y372C mutant FGFRl, whereby the soluble form of Y372C mutant FGFRl functions as a competitive antagonist of cellular FGFRl, thereby alleviating the disorder in the mammal. In an aspect of the invention, the mammal is a human.

The present invention includes a method of treating a hypophosphatemic disorder in a mammal, whereby the method comprises administering to a mammal afflicted with such a disorder a therapeutically effective amount of a soluble form of a mutant FGFRl polypeptide encoded by a polynucleotide comprising the polynucleotide set forth in SEQ ID NO: 1 , whereby the soluble form of the mutant FGFRl polypeptide functions as a competitive antagonist of cellular FGFRl, thereby alleviating said disorder in said mammal. In an aspect of the present invention, the mammal is a human.

The present invention includes a method of treating a hypophosphatemic disorder in a mammal, whereby the method comprises administering to a mammal afflicted with such a disorder a therapeutically effective amount of a soluble fragment of FGFRl, whereby the soluble fragment of FGFRl functions as a competitive antagonist of cellular FGFRl, thereby alleviating the disorder in the mammal. In an aspect of the present invention, the mammal is a human.

The present invention includes a method of treating a hypophosphatemic disorder in a mammal, whereby the method comprises administering to a mammal afflicted with said disorder a therapeutically effective amount of a soluble fragment of FGFRl, whereby the soluble fragment of FGFRl functions as a competitive antagonist of cellular FGFRl by inhibiting FGFRl -FGF23 interaction, thereby alleviating the disorder in the mammal. In one aspect of the present invention, the mammal is a human.

l-PH/1977697.1 f, In an embodiment of the invention, a hypophosphatemic disorder is selected from the group consisting of craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia.

Another aspect of the present invention provides a method of treating a phosphate homeostasis disorder in a mammal, comprising administering to a mammal afflicted with such a disorder a therapeutically effective amount of an FGFRl antagonist, thereby alleviating the phosphate homeostasis disorder in the mammal. In one aspect of the invention, the mammal is a human. In an embodiment of the invention, a phosphate homeostasis disorder may be a hyperphosphatemic disorder or a hypophosphatemic disorder. In yet a further embodiment of the invention, the phosphate homeostasis disorder may be craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, or fibrous dysplasia.

The present invention features a method of treating a phosphate homeostasis disorder in a mammal, whereby the method comprises administering to a mammal afflicted with such a disorder a therapeutically effective amount of an FGFRl antagonist, thereby alleviating the phosphate homeostasis disorder in the mammal. In an aspect of the invention, the mammal is a human.

In one embodiment of the invention, the FGFRl antagonist is a competitive antagonist. Such an FGFRl antagonist may be wild type FGFRl, a mutant FGFRl, or an FGFRl fragment. In an aspect of the invention, such an FGFRl antagonist inhibits FGFRl -FGF23 binding. In another aspect of the invention, such an FGFRl antagonist enhances FGFRl -FGF23 binding.

In an aspect of the invention, an FGFRl antagonist binds to FGFRl. In another aspect of the invention, an FGFRl antagonist binds to FGF23. In another aspect of the invention, an FGFRl antagonist simultaneously binds to FGFRl and FGF23. In yet another aspect of the invention, an FGFRl antagonist has the properties of binding to FGFRl and FGF23, but binds to only one of FGFRl and

l-PH/ 1977697.1 "^'"FGF23 at ^"any ^"given^" instant. FGFRl antagonists of the invention may be a peptide, a protein, a small organic molecule, a large organic molecule, a carbohydrate, or a lipid.

The present invention features a method of diagnosing a phosphate homeostasis disorder in a mammal, said method comprising contacting a mammalian biological sample with a reagent that detects the presence or absence of a mutation in a nucleic acid encoding FGFRl, wherein such a mutation encodes a Y372C FGFRl mutant protein as set forth in SEQ ID NO:2, assessing the presence or absence of the mutation in a sample, wherein the presence of the mutation is an indication that a mammal is afflicted with the disorder, thereby diagnosing the phosphate homeostasis disorder in a mammal. In an aspect of the invention, a phosphate homeostasis disorder may be craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, tumor induced osteomalacia, epidermal nevus syndrome, or fibrous dysplasia.

In an embodiment of the present invention, a diagnostic method can detect a nucleic acid encoding a Y372C FGFRl protein. In one aspect of the invention, such a nucleic acid contains a A1115->G1115 mutation. In another aspect of the invention, a nucleic acid encoding a Y372C FGFRl protein comprises a Al 115- G1115 mutation and a Cl 116- T1116 mutation.

Diagnostic methods of the invention may contain a reagent that is a nucleic acid. In another embodiment of the invention, a reagent is detectably labeled. In another embodiment of the invention, a reagent is detectably labeled with a label selected from the group consisting of a radioisotope, a bioluminescent compound, a chemiluminescent compound, a fluorescent compound, a metal chelate, and an enzyme. The present invention features a method of diagnosing a phosphate homeostasis disorder in a mammal, wherein the method comprises contacting a mammalian biological sample with a reagent that detects the presence or absence of a Y372C mutation in an FGFRl polypeptide, assessing the presence or absence of such a mutation in a sample, wherein the presence of the mutation is an indication that a mammal is afflicted with the disorder, thereby diagnosing the phosphate homeostasis disorder in a mammal. Phosphate homeostasis disorders of the invention include craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis,

l-PH/l 977697.1 S X^lϊnked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia. In an aspect of the invention, a diagnostic reagent is an FGFRl antibody. In another aspect of the invention, such a reagent is detectably labeled. In a further aspect of the invention, such a reagent is detectably labeled with a label selected from the group consisting of a radioisotope, a bioluminescent compound, a chemiluminescent compound, a fluorescent compound, a metal chelate, and an enzyme.

The present invention features a kit for diagnosing a phosphate homeostasis disorder in a mammal, wherein such a kit comprises a reagent which detects the presence or absence of a mutation in a nucleic acid sequence encoding FGFRl, wherein the mutation encodes for a Y372C FGFRl mutant protein as set forth in SEQ ID NO:2 and further wherein the presence of such a mutation is an indication that a mammal is afflicted with a disorder. A kit of the invention further comprises an applicator and an instructional material for the use thereof. A kit of the present invention is useful for diagnosing a hyperphosphatemic disorder or a hypophosphatemic disorder, such disorders including craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia. In an aspect of the present invention, a diagnostic kit includes a nucleic acid encoding a Y372C FGFRl protein, wherein such a nucleic acid contains a A1115->G1115 mutation. In an embodiment of the invention, a kit contains a reagent that is a nucleic acid. In another aspect of the invention, such a reagent is detectably labeled. In yet another aspect of the invention, a reagent is detectably labeled with a label selected from the group consisting of a radioisotope, a bioluminescent compound, a chemiluminescent compound, a fluorescent compound, a metal chelate, and an enzyme.

The present invention also features a kit for diagnosing a phosphate homeostasis disorder in a mammal, wherein such a kit comprises a reagent which detects the presence or absence of a Y372C mutation in an FGFRl polypeptide, wherein the presence of such a mutation is an indication that a mammal is afflicted with a disorder, and the kit further comprises an applicator and an instructional

l-PH/1977697.1 Q material for the use thereof. A kit of the present invention is useful for detecting a phosphate homeostasis disorder is selected from the group consisting of craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia.

In an aspect of the present invention, a diagnostic kit contains a reagent that is an FGFRl antibody. In another aspect of the invention, such a reagent is detectably labeled. In yet another aspect of the invention, such a reagent is detectably labeled with a label selected from the group consisting of a radioisotope, a bioluminescent compound, a chemiluminescent compound, a fluorescent compound, a metal chelate, and an enzyme.

The present invention also features a kit for diagnosing a phosphate homeostasis disorder in a mammal, wherein such a kit comprises a reagent which detects the level of a FGFRl polypeptide in a sample, wherein an increase or decrease in the level of FGFRl polypeptide compared with the level of FGFRl in a mammal not afflicted with a phosphate homeostasis disorder is an indication that a mammal is afflicted with the phosphate homeostasis disorder, and the kit further comprises an applicator and an instructional material for the use thereof. Phosphate homeostasis disorders diagnosed by a kit of the present invention include craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia.

In an aspect of the invention, a kit contains a reagent that is an FGFRl antibody. In another aspect of the invention, such a reagent is detectably labeled. In yet another aspect of the invention, such a reagent is detectably labeled with a label selected from the group consisting of a radioisotope, a bioluminescent compound, a chemiluminescent compound, a fluorescent compound, a metal chelate, and an enzyme.

The present invention features an isolated nucleic acid comprising the nucleic acid set forth in SEQ ID NO: 1. In an embodiment of the invention, such an isolated nucleic acid encodes an FGFRl polypeptide. In another embodiment of the invention, such an isolated nucleic acid encodes a mutant FGFRl polypeptide. In still

l-PH/1977697 1 \Q another aspect of the invention, such an isolated nucleic acid encodes a Y372C FGFRl polypeptide. Still another aspect of the invention provides an isolated nucleic acid comprising a nucleic acid encoding the polypeptide set forth in SEQ ID NO:2. In an embodiment of the present invention, an isolated nucleic acid encoding FGFRl, or a mutant, variant, homolog, or fragment thereof, also contains a nucleic acid encoding a tag polypeptide covalently linked thereto. Such nucleic acid tags include tags encoding a polypeptide tag such as a myc tag polypeptide, a glutathione-S-transferase tag polypeptide, a green fluorescent protein tag polypeptide, a myc-pyruvate kinase tag polypeptide, a His6 tag polypeptide, an influenza virus hemagglutinin tag polypeptide, a flag tag polypeptide, a V5 tag, and a maltose binding protein tag polypeptide.

In an embodiment of the present invention, an isolated nucleic acid encoding FGFRl, or a mutant, variant, homolog, or fragment thereof, also contains a nucleic acid encoding a promoter/regulatory sequence operably linked thereto. The present invention also features a vector containing an isolated nucleic acid encoding FGFRl, or a mutant, variant, homolog, or fragment thereof. In an embodiment of the invention, a vector further comprises a nucleic acid specifying a promoter/regulatory sequence operably linked thereto.

The present invention also features a recombinant cell containing an isolated nucleic acid encoding FGFRl, or a mutant, variant, homolog, or fragment thereof. In an embodiment of the invention, a recombinant cell of the invention may contain a vector of the invention, as set forth more fully below.

The present invention features an isolated nucleic acid complementary to a nucleic acid encoding the Y372C mutant FGFRl set forth in SEQ ID NO:l, wherein such a complementary nucleic acid is in an antisense orientation. One embodiment of the present invention provides a vector comprising an isolated nucleic acid complementary to a nucleic acid encoding the Y372C mutant FGFRl set forth in SEQ ID NO: 1, wherein such a complementary nucleic acid is in an antisense orientation. Another embodiment of the invention provides a vector comprising an isolated nucleic acid complementary to a nucleic acid encoding the Y372C mutant FGFRl set forth in SEQ ID NO:l, wherein such a complementary nucleic acid is in an antisense orientation, wherein the vector further comprises a nucleic acid

l-PH/1977697.1 \ \ specifying a promoter/regulatory sequence operably linked thereto. The present invention also provides a recombinant cell comprising the isolated nucleic acid of any of the above-mentioned vectors.

The present invention features a transgenic non-human mammal containing an isolated nucleic acid encoding a Y372C mutant FGFRl set forth in SEQ ID NO:2. In an embodiment of the invention, a transgeneic non-human mammal contains an isolated nucleic acid encoding a Y374C mutant FGFRl.

One aspect of the present invention provides an isolated polypeptide comprising the Y372C FGFRl mutant protein set forth in SEQ ID NO:2. The present invention also provides a composition comprising the polypeptide comprising the

Y372C FGFRl mutant protein set forth in SEQ ID NO:2, or a fragment thereof, and a pharmaceutically-acceptable carrier. The present invention also provides a composition comprising the polypeptide comprising a Y374C FGFRl mutant protein, or a fragment thereof, and a pharmaceutically-acceptable carrier. One aspect of the present invention provides an isolated antibody that specifically binds with the Y372C FGFRl mutant protein set forth in SEQ ID NO:2. Another aspect of the present invention provides an isolated antibody that specifically binds with the Y374C FGFRl mutant protein. In an embodiment of the invention, an antibody is selected from the group consisting of a polyclonal antibody, a monoclonal antibody, a humanized antibody, a chimeric antibody, and a synthetic antibody. The present invention also provides a composition comprising the polypeptide of claim 74, or a fragment thereof, and a pharmaceutically-acceptable carrier.

The present invention features a method of identifying a compound that modulates a phosphate homeostasis disorder in a cell, wherein the method comprises contacting a cell with a test compound known to bind FGFRl and comparing the severity of the phosphate homeostasis disorder in said cell with the severity of a phosphate homeostasis disorder in an otherwise identical cell not contacted with the test compound, wherein a greater or lesser severity of the phosphate homeostasis disorder in a cell contacted with the test compound compared with the severity of a phosphate homeostasis disorder in an otherwise identical cell not contacted with the test compound is an indication that the test compound binds FGFRl in a cell, thereby identifying a compound that modulates a phosphate

l-PH/ 1977697.1 γ Homeostasis disorder in a cell. Une embodiment of the present invention provides a compound identified by the above method of identifying a compound that modulates a phosphate homeostasis disorder in a cell.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Figure 1 is an illustration of the structure of FGFRl. Ig connotates the extracellular immunoglobulin-like domains I-III; TM indicates the transmembrane domain; TK indicates the tyrosine kinase domains 1-2; bold double line within Iglll represents the Illb/IIIc splicing region. The arrow depicts the position of the Y372C mutation. The sequence alignment compares human FGFRl, FGFR2, and FGFR3, and mouse FGFRl. The alignment encompasses the regions adjacent to, and containing the transmembrane domain (boxed region). Conserved residues are bold, and the Y-^C mutation positions are shown for each receptor. Homologous mutations in human FGFR2 and FGFR3 cause neonatal lethal syndromes. Mouse and human FGFRl/Fgfrl are highly conserved in this region, with valine to isolucine mutation at position 394 being the only substitution.

Figure 2 is a series of images illustrating that the heterozygous A/G missense mutation responsible for CFDH (mutation indicated by arrow) segregates with the affected individuals in the family as detected by DNA sequencing, and that the mutation was not present in control subjects or in the unaffected grandmother.

Figure 3 a and Figure 3b together illustrate the amino acid sequence of the FGFRl IIIc isoform Y374C mutant (SEQ ID NO: 12). The Y374C mutation is indicated by large, bold font. Figure 4 illustrates the amino acid sequence of the FGFRl IIIc isoform

Y372C mutant (SEQ ID NO:2). The Y372C mutation is indicated by large, bold font.

DETAILED DESCRIPTION OF THE INVENTION The kidney plays a major role in maintaining proper serum phosphate concentrations. The identification of genes that cause rare heritable disorders of impaired phosphate regulation provide an opportunity to discover renal pathways that control mineral ion balance. The instant invention relates to the discovery of a novel

l-PH/1977697.1 13 ' mutant nucleic acid encoding a mammalian fibroblast growth factor receptor-1 (FGFRl) and proteins encoded thereby. The invention discloses novel members of the fibroblast growth factor receptor family in which the nucleic acid and protein encoded thereby are useful for the development of diagnostic and therapeutic reagents for the diagnosis and treatment of hypophosphatemic and hyperphosphatemic disorders.

The present invention demonstrates that mutations in FGFRl can be responsible for distinct disorders of phosphate handling. Described herein are polynucleotides and polypeptides for a novel FGFRl mutant. Therefore, the invention features the cloning and or mutagenesis of both wild type and mutant

FGFRl polynucleotides. In the present invention, FGFRl polypeptides encoded by FGFRl polynucleotides of the invention, and the polypeptides so expressed, are isolated and characterized.

The invention particularly features the Al 115G mutant FGFRl polynucleotide, wherein the adenine located at position 1115, according to the numbering of the FGFRl gene, is mutated to a guanine. The Al 115->G1115 ("Al 115G") mutation is located within exon 10 of the FGFRl gene, and results in a change in the identity of a single codon within the FGFRl gene that, upon translation, results in the substitution of a cysteine residue for the tyrosine residue normally found in the wild type FGFRl sequence.

The human gene encoding FGFRl is comprised of a total of nineteen (19) exons. Differential splicing of the nineteen exons of the human FGFRl gene results in FGFRl receptor isoforms that may differ by zero, at least one, and possibly, multiple amino acid residues. Within Ig-like domain III of FGFRl, -2 and -3, either of two mutually exclusive exons can be inserted to produce "Illb" or "IIIc" receptor isoforms (the "a" isoforms of FGFRl, -2 and -3 do not contain transmembrane domains and are thought to be "decoy" receptors). In addition, "beta" isoforms of FGFRl, -2 and -3 exist, wherein such FGF receptors containin two Ig like domains (domins II and III) and "alpha" isoforms of FGFRl, -2 and -3 exist, wherein all three Ig-like domins (I, II and III) are present in the FGFR. RT-PCR amplification of cDNAs have also demonstrated the possibility of kinase-deficient FGFRl s with limited signaling capabilities (Wang et al, 1995, JBC 270:10231). Thus, the present

I-PH/1977697.1 \A invention includes a polypeptide encoded by an isolated Al 115G mutant FGFRl polynucleotide which has undergone alternative splicing. The invention particularly features a polypeptide that is encoded by an Al 115G mutant FGFRl alternatively- spliced polynucleotide, such that a cysteine residue is substituted for the wild type tyrosine residue at amino acid position 372 of the polypeptide encoded by the Al 115G FGFRl isolated polynucleotide. Further, the invention also features a polypeptide that is encoded by an Al 115G mutant FGFRl alternatively-spliced polynucleotide, such that a cysteine residue is substituted for the wild type tyrosine residue at amino acid position 374 of the polypeptide encoded by the Al 115G FGFRl isolated polynucleotide.

The present invention includes the clinical and genetic presentation of a new disorder, an autosomal dominant hypophosphatemic dysplasia hereinafter referred to as craniofacial dysplasia with hypophosphatemia (CFDH). In the present invention, the gene responsible for CFDH has been discovered and has been identified as FGFRl containing an Al 115G mutation in exon 10. CFDH is characterized by short limb dwarfism and severe cranio-facial deformities, including craniosynostosis. Cosegregating with the skeletal manifestations of CFDH are conditions of renal phosphate wasting and extreme hypophosphatemia, with inappropriately low or undetectable serum l,25(OH)₂ vitamin D concentrations. The invention therefore provides methods of detection, analysis, and treatment of disorders of bone biology and disorders of vitamin D metabolism related to mutations in FGFRl.

Compositions and methods for diagnosis and treatment of disorders involving the FGFRl polynucleotides and polypeptides of the invention are also provided in the present invention. A key feature of the present invention therefore includes the use and detection of an FGFRl mutant encoded by an FGFRl polynucleotide containing an Al 115G mutation in the exon 10 region. Another feature of the present invention includes the use and detection of a Y372C FGFRl polypeptide and the use and detection of a Y374C FGFRl polypeptide.

Additionally, the present invention discloses that patients suffering from CFDH share biochemical and clinical similarities with patients suffering from oncogenic hypophosphatemic osteomalacia and also with ADHR patients. The biochemical and clinical profiles of CFDH patients are similar to the biochemical and

l-PH/1977697.1 15 clinical profiles of those patients suffering from ADHR and other FGF-23 -based disorders. A key feature of the present invention, therefore, is the identification, characterization, and use of an FGF-23 receptor, discovered in the present invention as being FGFRl. The present invention discloses that FGFRl is a receptor for FGF23.

Specifically, similar biochemical and clinical profiles are shown for patients having elevated levels of FGF23 and patients having increased FGFRl activity. A key feature of the present invention, therefore, is to alleviate a phosphate homeostasis disorder, a vitamin D metabolism disorder, or a long bone growth disorder that arises in connection with perturbed FGFRl -FGF23 interaction.

Further, the present invention encompasses such disorders as set forth above arising from perturbations in the interaction of FGF23 with an FGFRl mutant. For example, phosphate disorders that may be treated through FGF23 interaction with mutant FGFRl include craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linlced hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, fibrous dysplasia, and HBD. Other disorders that may be treated through FGF23 interaction with mutant FGFRl include disorders of vitamin D metabolism and disorders of long bone growth.

Definitions

As used herein, each of the following terms has the meaning associated with it in this section.

The articles "a" and "an" are used herein to refer to one or to more than one (i.e. to at least one) of the grammatical object of the article. By way of example, "an element" means one element or more than one element.

"Alternative splicing" refers to the process by which a single pre- mRNA molecule, transcribed from one or more exons, may be spliced ("processed") in more than one way to produce different versions of the same mRNA. A result of the differential splicing of a pre-mRNA molecule is the eventual translation of different proteins. For example, it is possible that the different proteins resulting from the alternative splicing of a pre-mRNA are so similar that the multiple different

l-PH/l 977697.1 lg proteins^' have identical^' functions, identical activities, and identical properties, and may differ by as little as a single amino acid. By way of another example, is also possible that the different proteins resulting from alternative splicing are so different that the multiple different proteins have no overlapping functions, activities, or properties, and the multiple different proteins may differ by multiple, and even a majority of amino acids.

"Amplification" refers to any means by which a polynucleotide sequence is copied and thus expanded into a larger number of polynucleotide molecules, e.g., by reverse transcription, polymerase chain reaction, and ligase chain reaction.

"Antisense" refers particularly to the nucleic acid sequence of the non- coding strand of a double stranded DNA molecule encoding a protein, or to a sequence which is substantially homologous to the non-coding strand. As defined herein, an antisense sequence is complementary to the sequence of a double stranded DNA molecule encoding a protein. It is not necessary that the antisense sequence be complementary solely to the coding portion of the coding strand of the DNA molecule. The antisense sequence may be complementary to regulatory sequences specified on the coding strand of a DNA molecule encoding a protein, which regulatory sequences control expression of the coding sequences. The term "antibody," as used herein, refers to an immunoglobulin molecule which is able to specifically bind to a specific epitope on an antigen. Antibodies can be intact immunoglobulins derived from natural sources or from recombinant sources and can be immunoreactive portions of intact immunoglobulins. Antibodies are typically tetramers of immunoglobulin molecules. The antibodies in the present invention may exist in a variety of forms including, for example, polyclonal antibodies, monoclonal antibodies, Fv, Fab and F(ab)₂, as well as single chain antibodies and humanized antibodies (Harlow et al., 1999, Using Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, NY; Harlow et al., 1989, Antibodies: A Laboratory Manual, Cold Spring Harbor, New York; Houston et al., 1988, Proc. Natl. Acad. Sci. USA 85:5879-5883; Bird et al., 1988, Science 242:423- 426).

l-PH/1977697 1 η By the term "synthetic antibody" as used herein, is meant an antibody which is generated using recombinant DNA technology, such as, for example, an antibody expressed by a bacteriophage as described herein. The term should also be construed to mean an antibody which has been generated by the synthesis of a DNA molecule encoding the antibody and which DNA molecule expresses an antibody protein, or an amino acid sequence specifying the antibody, wherein the DNA or amino acid sequence has been obtained using synthetic DNA or amino acid sequence technology which is available and well known in the art.

By the term "applicator" as the term is used herein, is meant any device including, but not limited to, a hypodermic syringe, a pipette, and the like, for administering an FGFRl nucleic acid, protein, and/or anti-FGFRl antibodies and the antisense FGFRl nucleic acid of the invention to a mammal.

As used herein, "amino acids" are represented by the full name thereof, by the three letter code corresponding thereto, or by the one-letter code corresponding thereto, as indicated in the following table:

Full Name Three-Letter Code One-Letter Code

Aspartic Acid Asp D

Glutamic Acid Glu E

Lysine Lys K

Arginine Arg R

Histidine His H

Tyrosine Tyr Y

Cysteine Cys C

Asparagine Asn N

Glutamine Gin Q

Serine Ser s

Threonine Thr T

Glycine Gly G

Alanine Ala A

Valine Val V

Leucine Leu L

Isoleucine He I

l-PH/1977697.1 i s Metfiiόnine Met M

Proline Pro P

Phenylalanine Phe F

Tryptophan Trp W

"Biological sample," as that term is used herein, means a sample obtained from a mammal that can be used to assess the level of expression of an FGFRl polynucleotide, the level of FGFRl protein present in the sample, or both. Such a sample includes, but is not limited to, a blood sample, a neural tissue sample, a brain sample, and a cerebrospinal fluid sample. One of skill in the art will understand that such a biological sample may be used in connection with diagnostic methods of the present invention, as well as with assays for the properties and biological activities of FGFRl, including, but not limited to FGFRl dimerization and FGFRl interactions with ligands. "Cleavage" is used herein to refer to the disassociation of a peptide bond between two amino acids in a polypeptide, thereby separating the polypeptide comprising the two amino acids into at least two fragments.

By "complementary to a portion or all of a polynucleotide encoding an FGFRl polypeptide" is meant a sequence of nucleic acid which does not encode an FGFRl polypeptide. Rather, the sequence which is being expressed in the cells is identical to the non-coding strand of the polynucleotide encoding a FGFRl polypeptide and thus, does not encode an FGFRl polypeptide. The terms "complementary" and "antisense" as used herein, are not entirely synonymous. "Antisense" refers particularly to the nucleic acid sequence of the non-coding strand of a double stranded DNA molecule encoding a protein, or to a sequence which is substantially homologous to the non-coding strand.

"Complementary" as used herein refers to the broad concept of subunit sequence complementarity between two nucleic acids, e.g., two DNA molecules. When a nucleotide position in both of the molecules is occupied by nucleotides normally capable of base pairing with each other, then the nucleic acids are considered to be complementary to each other at this position. Thus, two nucleic acids are complementary to each other when a substantial number (at least 50%) of

l-PH/1977697.1 19 corresponding positions in each of the molecules are occupied by nucleotides which normally base pair with each other (e.g., A:T and G:C nucleotide pairs). As defined herein, an antisense sequence is complementary to the sequence of a double stranded DNA molecule encoding a protein. It is not necessary that the antisense sequence be complementary solely to the coding portion of the coding strand of the DNA molecule. The antisense sequence may be complementary to regulatory sequences specified on the coding strand of a DNA molecule encoding a protein, which regulatory sequences control expression of the coding sequences.

A "compound" as the term is used herein is any molecule that would be recognized as a potential "drug" to one of skill in the art. Non-limiting examples of molecules commonly referred to as compounds, and representative of the types of molecules considered as "compounds" in the present application include

A "coding region" of a gene consists of the nucleotide residues of the coding strand of the gene and the nucleotides of the non-coding strand of the gene which are homologous with or complementary to, respectively, the coding region of an mRNA molecule which is produced by transcription of the gene.

A "coding region" of an mRNA molecule also consists of the nucleotide residues of the mRNA molecule which are matched with an anticodon region of a transfer RNA molecule during translation of the mRNA molecule or which encode a stop codon. The coding region may thus include nucleotide residues corresponding to amino acid residues which are not present in the mature protein encoded by the mRNA molecule (e.g. amino acid residues in a protein export signal sequence).

The "effective concentration" of a polypeptide of the invention is the threshold availability of a biologically active polypeptide of interest, below which the biological function of the polypeptide is not observed in an organism. For example, the effective concentration of a cellular receptor is the point below which, for a particular reason (such as inhibition with a drug via binding of the drug molecule to the polypeptide), the overall number of cellular receptors contributing to the recognized biological function of that receptor is no longer sufficient to maintain what is recognized as "normal" or "typical" biological homeostasis.

l-PH/l 977697.1 20 " " ^{' '} "Ehcό^"dmg^,r'refers to the inherent property of specific sequences of nucleotides in a polynucleotide, such as a gene, a cDNA, or an mRNA, to serve as templates for synthesis of other polymers and macromolecules in biological processes having either a defined sequence of nucleotides (i.e., rRNA, tRNA and mRNA) or a defined sequence of amino acids and the biological properties resulting therefrom. Thus, a gene encodes a protein if transcription and translation of mRNA corresponding to that gene produces the protein in a cell or other biological system. Both the coding strand, the nucleotide sequence of which is identical to the mRNA sequence and is usually provided in sequence listings, and the non-coding strand, used as the template for transcription of a gene or cDNA, can be referred to as encoding the protein or other product of that gene or cDNA.

"Expression vector" refers to a vector comprising a recombinant polynucleotide comprising expression control sequences operatively linked to a nucleotide sequence to be expressed. An expression vector comprises sufficient cis- acting elements for expression; other elements for expression can be supplied by the host cell or in an in vitro expression system. Expression vectors include all those known in the art, such as cosmids, plasmids (e.g., naked or contained in liposomes) and viruses that incorporate the recombinant polynucleotide.

A first region of an oligonucleotide "flanks" a second region of the oligonucleotide if the two regions are adjacent one another or if the two regions are separated by no more than about 1000 nucleotide residues, and preferably no more than about 100 nucleotide residues.

As used herein, the term "fragment" as applied to a nucleic acid, may ordinarily be at least about 20 nucleotides in length, typically, at least about 50 nucleotides, more typically, from about 50 to about 100 nucleotides, preferably, at least about 100 to about 500 nucleotides, even more preferably, at least about 500 nucleotides to about 1000 nucleotides, yet even more preferably, at least about 1000 to about 1500, even more preferably, at least about 1500 nucleotides to about 2000 nucleotides, yet even more preferably, at least about 2000 to about 2500, even more preferably, at least about 2500 nucleotides to about 2600 nucleotides, yet even more preferably, at least about 2600 to about 2650, and most preferably, the nucleic acid fragment will be greater than about 2652 nucleotides in length.

l-PH/1977697.1 21 As applied^{' '}to a protein, a "fragment" of FGFRl is about 20 amino acids in length. More preferably, the fragment of FGFRl is about 100 amino acids, even more preferably, at least about 200, yet more preferably, at least about 300, even more preferably, at least about 400, yet more preferably, at least about 500, even more preferably, about 600, and even more preferably, at least about 650 amino acids in length.

"FGFRl" or "wild type FGFRl" as the terms are used synonymously herein, refers to the Fibroblast Growth Factor Receptor-1, present in its naturally- occurring state in a mammal. "Mutant FGFRl" as used herein refers to FGFRl in which at least one amino acid residue has been altered, such as the substitution of a cysteine residue for a tyrosine residue. Mutant FGFRl also encompasses FGFRl in which at least one amino acid residue has been inserted into the FGFRl sequence (i.e., "added") or in which at least one amino acid residue has been deleted from the FGFRl sequence (i.e., "removed"). Mutant FGFRl will also be understood to encompass an FGFRl that has any number and combination of amino acid substitutions, insertions, and deletions. "Y372C FGFRl" as used herein refers to FGFRl wherein the tyrosine (Y) residue at amino acid position 372 has been replaced with a cysteine (C). Other FGFRl mutants are referred to in a similar manner, i.e., the abbreviation FGFRl is preceded by an indication of the wild type residue ("Y"), followed by a number indicating the position of that wild type residue ("372"), followed by the residue that has replaced the wild type residue in the particular FGFRl mutant under consideration ("C").

When the term "FGFRl" is used and is neither preceeded nor followed by any modifying terms, such as "wild-type" or "mutant," it will be understood that such a reference to FGFRl should be construed as referring to every possible form, mutant, homolog, and variant of FGFRl. By way of a non-limiting example, the recitation of "FGFRl polypeptide" encompasses wild type FGFRl polypeptide, Y372C FGFRl polypeptide, soluble FGFRl polypeptide, truncated FGFRl polypeptide, FGFRl polypeptide fragments possessing FGFRl biological activity, and FGFRl fusion proteins.

"FGFRl isoforms" or "alternatively-spliced FGFRl" describes FGFRl molecules sharing less than 100% identity with one another. Because FGFRl

l-PH/1977697.1 22 undergoes alternative splicing, it will be understood that FGFRl polynucleotide and polypeptide molecules may have similar or identical activity, properties, and functions, while the sequences of such molecules may differ from one another by one or more nucleotide residues or amino acid residues, whereby such residues are substitutions, insertions, or deletions, or any number and combination thereof. It will be understood that isoforms of FGFRl encompass isoforms of wild type FGFRl as well as isoforms of mutant FGFRl. For example, an Al 115G mutation in exon 10 may give rise to either a Y372C FGFRl polypeptide or a Y374C polypeptide, depending upon the alternative splicing of the pre-mRNA transcript for the mutant FGFRl.

An "FGFRl -modulating compound" is a compound that has the property of altering the structure, properties, function, role, and/or activity of FGFRl. It will be appreciated that any structure, property, function, role, and/or activity of FGFRl altered by an FGFRl -modulating compound may be enhanced, diminished, increased, decreased, or eliminated. For example, an FGFRl -modulating compound may enhance the biological activity of FGFRl. As another example, and FGFRl - modulating compound may inhibit the biological activity of FGFRl.

An "FGFRl ligand" is any molecule that interacts with, or binds to FGFRl. For example, FGF23 is an FGFRl ligand, as FGF23 binds to FGFRl. By way of another example, a small molecule that binds to FGFRl, identified by way of a compound-screening technique, is an FGFRl ligand. By way of yet another non- limiting example, FGFRl may dimerize, and in such an FGFRl -FGFRl interaction, a second molecule of FGFRl, or a mutant, fragement, homolog, or variant thereof, is a ligand for a first molecule of FGFRl. One of skill in the art will understand that "FGFRl ligand" may refer to a ligand for FGFRl polypeptide as well as FGFRl polynucleotide.

"Homologous" as used herein, refers to nucleotide sequence similarity between two regions of the same nucleic acid strand or between regions of two different nucleic acid strands. When a nucleotide residue position in both regions is occupied by the same nucleotide residue, then the regions are homologous at that position. A first region is homologous to a second region if at least one nucleotide residue position of each region is occupied by the same residue. Homology between

l-PH/1977697.1 23 two "regions^' is expressed in terms of the proportion of nucleotide residue positions of the two regions that are occupied by the same nucleotide residue. By way of example, a region having the nucleotide sequence 5'-ATTGCC-3' and a region having the nucleotide sequence 5'-TATGGC-3' share 50% homology. Preferably, the first region comprises a first portion and the second region comprises a second portion, whereby, at least about 50%, and preferably at least about 75%, at least about 90%, or at least about 95% of the nucleotide residue positions of each of the portions are occupied by the same nucleotide residue. More preferably, all nucleotide residue positions of each of the portions are occupied by the same nucleotide residue. As used herein, "homology" is used synonymously with "identity."

As used herein, an "instructional material" includes a publication, a recording, a diagram, or any other medium of expression which can be used to communicate the usefulness of the composition of the invention for its designated use. The instructional material of the kit of the invention may, for example, be affixed to a container which contains the composition or be shipped together with a container which contains the composition. Alternatively, the instructional material may be shipped separately from the container with the intention that the instructional material and the composition be used cooperatively by the recipient.

An "isolated nucleic acid" refers to a nucleic acid segment or fragment which has been separated from sequences which flank it in a naturally occurring state, e.g., a DNA fragment which has been removed from the sequences which are normally adjacent to the fragment, e.g., the sequences adjacent to the fragment in a genome in which it naturally occurs. The term also applies to nucleic acids which have been substantially purified from other components which naturally accompany the nucleic acid, e.g., RNA or DNA or proteins, which naturally accompany it in the cell. The term therefore includes, for example, a recombinant DNA which is incorporated into a vector, into an autonomously replicating plasmid or virus, or into the genomic DNA of a prokaryote or eukaryote, or which exists as a separate molecule (e.g, as a cDNA or a genomic or cDNA fragment produced by PCR or restriction enzyme digestion) independent of other sequences. It also includes a recombinant DNA which is part of a hybrid gene encoding additional polypeptide sequence.

l-PH/1977697 1 24 "Naturaϊϊy-occurring" as applied to an object refers to the fact that the object can be found in nature. For example, a polypeptide or polynucleotide sequence that is present in an organism (including viruses) that can be isolated from a source in nature and which has not been intentionally modified by man is naturally-occurring. In the context of the present invention, the following abbreviations for the commonly occurring nucleic acid bases are used. "A" refers to adenosine, "C" refers to cytidine, "G" refers to guanosine, "T" refers to thymidine, and "U" refers to uridine.

Unless otherwise specified, a "nucleotide sequence encoding an amino acid sequence" includes all nucleotide sequences that are degenerate versions of each other and that encode the same amino acid sequence. Nucleotide sequences that encode proteins and RNA may include introns.

By describing two polynucleotides as "operably linked" is meant that a single-stranded or double-stranded nucleic acid moiety comprises the two polynucleotides arranged within the nucleic acid moiety in such a manner that at least one of the two polynucleotides is able to exert a physiological effect by which it is characterized upon the other. By way of example, a promoter operably linked to the coding region of a gene is able to promote transcription of the coding region.

A "polynucleotide" means a single strand or parallel and anti-parallel strands of a nucleic acid. Thus, a polynucleotide may be either a single-stranded or a double-stranded nucleic acid.

The term "nucleic acid" typically refers to large polynucleotides.

The term "oligonucleotide" typically refers to short polynucleotides, generally no greater than about 50 nucleotides. It will be understood that when a nucleotide sequence is represented by a DNA sequence (i.e., A, T, G, C), this also includes an RNA sequence (i.e., A, U, G, C) in which "U" replaces "T."

Conventional notation is used herein to describe polynucleotide sequences: the left-hand end of a single-stranded polynucleotide sequence is the 5'- end; the left-hand direction of a double-stranded polynucleotide sequence is referred to as the 5'-direction.

The direction of 5' to 3' addition of nucleotides to nascent RNA transcripts is referred to as the transcription direction. The DNA strand having the

l-PH/1977697.1 25 "same^" sequence as an mRNA is referred to as the "coding strand"; sequences on the DNA strand which are located 5' to a reference point on the DNA are referred to as "upstream sequences"; sequences on the DNA strand which are 3' to a reference point on the DNA are referred to as "downstream sequences." A "portion" of a polynucleotide means at least at least about twenty sequential nucleotide residues of the polynucleotide. It is understood that a portion of a polynucleotide may include every nucleotide residue of the polynucleotide.

"Primer" refers to a polynucleotide that is capable of specifically hybridizing to a designated polynucleotide template and providing a point of initiation for synthesis of a complementary polynucleotide. Such synthesis occurs when the polynucleotide primer is placed under conditions in which synthesis is induced, i.e., in the presence of nucleotides, a complementary polynucleotide template, and an agent for polymerization such as DNA polymerase. A primer is typically single-stranded, but may be double-stranded. Primers are typically deoxyribonucleic acids, but a wide variety of synthetic and naturally occurring primers are useful for many applications. A primer is complementary to the template to which it is designed to hybridize to serve as a site for the initiation of synthesis, but need not reflect the exact sequence of the template. In such a case, specific hybridization of the primer to the template depends on the stringency of the hybridization conditions. Primers can be labeled with, e.g., chromogenic, radioactive, or fluorescent moieties and used as detectable moieties.

As used herein, the term "proband" refers to a subject under consideration in a study, such as a human subject in a clinical study.

"Probe" refers to a polynucleotide that is capable of specifically hybridizing to a designated sequence of another polynucleotide. A probe specifically hybridizes to a target complementary polynucleotide, but need not reflect the exact complementary sequence of the template. In such a case, specific hybridization of the probe to the target depends on the stringency of the hybridization conditions. Probes can be labeled with, e.g., chromogenic, radioactive, or fluorescent moieties and used as detectable moieties.

"Recombinant polynucleotide" refers to a polynucleotide having sequences that are not naturally joined together. An amplified or assembled

-PH/1977697.1 26 ^•• ' ^' recombinant polynucleotide may be included in a suitable vector, and the vector can be used to transform a suitable host cell.

A recombinant polynucleotide may serve a non-coding function (e.g., promoter, origin of replication, ribosome-binding site, etc.) as well. 5 A host cell that comprises a recombinant polynucleotide is referred to as a "recombinant host cell." A gene which is expressed in a recombinant host cell wherein the gene comprises a recombinant polynucleotide, produces a "recombinant polypeptide."

A "recombinant polypeptide" is one which is produced upon 0 expression of a recombinant polynucleotide.

"Polypeptide" refers to a polymer composed of amino acid residues, related naturally occurring structural variants, and synthetic non-naturally occurring analogs thereof linked via peptide bonds, related naturally occurring structural variants, and synthetic non-naturally occurring analogs thereof. Synthetic 5 polypeptides can be synthesized, for example, using an automated polypeptide synthesizer.

The term "protein" typically refers to large polypeptides. The term "peptide" typically refers to short polypeptides. Conventional notation is used herein to portray polypeptide sequences: 0 the left-hand end of a polypeptide sequence is the amino-terminus; the right-hand end of a polypeptide sequence is the carboxyl-terminus.

As used herein, the term "promoter/regulatory sequence" means a nucleic acid sequence which is required for expression of a gene product operably linked to the promoter/regulator sequence. In some instances, this sequence may be 5 the core promoter sequence and in other instances, this sequence may also include an enhancer sequence and other regulatory elements which are required for expression of the gene product. The promoter/regulatory sequence may, for example, be one which expresses the gene product in a tissue specific manner.

A "therapeutic" treatment is a treatment administered to a subject who 0 exhibits signs of pathology for the purpose of diminishing or eliminating those signs.

-PH/1977697.1 27 A "therapeutically effective amount" of a compound is that amount of compound which is sufficient to provide a beneficial effect to the subject to which the compound is administered.

A "transgene", as used herein, means an exogenous nucleic acid sequence comprising a nucleic acid which encodes a promoter/regulatory sequence operably linked to nucleic acid which encodes an amino acid sequence, which exogenous nucleic acid is encoded by an animal or cell.

A "vector" is a composition of matter which comprises an isolated nucleic acid and which can be used to deliver the isolated nucleic acid to the interior of a cell. Numerous vectors are known in the art including, but not limited to, linear polynucleotides, polynucleotides associated with ionic or amphiphilic compounds, plasmids, and viruses. Thus, the term "vector" includes an autonomously replicating plasmid or a virus. The term should also be construed to include non-plasmid and non- iral compounds which facilitate transfer of nucleic acid into cells, such as, for example, polylysine compounds, liposomes, and the like. Examples of viral vectors include, but are not limited to, adenoviral vectors, adeno-associated virus vectors, retroviral vectors, and the like

Description

Isolated nucleic acids

The present invention includes an isolated nucleic acid encoding a mammalian mutant FGFRl molecule, or a fragment thereof, wherem the nucleic acid shares at least about 99.8% homology with a nucleic acid having the sequence of SEQ ID NO: 1. The mammal is preferably a human. Preferably, the nucleic acid is about 99.9% homologous to SEQ ID NO:l, disclosed herein. Even more preferably, the nucleic acid is SEQ ID NO:l. The isolated nucleic acid of the invention should be construed to include an RNA or a DNA sequence encoding a mutant FGFRl protein of the invention, and any modified forms thereof, including chemical modifications of the DNA or RNA which render the nucleotide sequence more stable when it is cell free or when it is associated with a cell. Chemical modifications of nucleotides may also be used to enhance the efficiency with which a nucleotide sequence is taken up

l-PH/1977697 1 28 By a cell^' or the efficiency with which it is expressed in a cell. Any and all combinations of modifications of the nucleotide sequences are contemplated in the present invention.

Isolated nucleic acids of the present invention are based in part on novel nucleotide mutations in the human gene for FGFRl . Alternative splicing of the 19 exons of the human FGFRl gene results in the production of multiple isoforms of FGFRl mRNA, which in turn, results in multiple isoforms of FGFRl polypeptides. For example, SEQ ID NO: 13 is the cDNA sequence of GenBank Accession No. M34641, representing an alternatively spliced transcript of FGFRl. Similarly, SEQ ID NO: 14 is the cDNA sequence of GenBank Accession No. X52833, representing another alternatively spliced transcript of FGFRl. Wild type FGFRl cDNA and protein sequences are set forth in SEQ ID NO:4 and SEQ ID NO:5, respectively.

Nucleotide mutations which form the basis in part for isolated nucleic acids of the present invention are found in exon 10, which is set forth in SEQ ID NO:10. In an aspect of the present invention, a mutation of Al 115->G1115, wherein the nucleotide numbering is based on the numbering convention of the human genomic FGFRl sequence (i.e., the human FGFRl gene), results in the production of a mutant FGFRl responsible for CFDH. SEQ ID NO: 11 illustrates exon 10 of human FGFRl, wherein the exon contains the Al 115-? GI 115 mutation. In an embodiment of the invention, an isolated polynucleotide is provided, wherein the polynucleotide encodes a Y372C mutant FGFRl polypeptide (SEQ ID NO:2). Such a polynucleotide is the product of alternative splicing of the human FGFRl gene. SEQ ID NO:l is a cDNA sequence representing an alternatively-spliced transcript of FGFRl, additionally having the exon 10 Al 115- G1115 mutation and encoding the Y372C FGFRl mutant polypeptide shown in SEQ ID NO:2. In another embodiment of the present invention, an isolated polynucleotide is provided, wherein the polynucleotide encodes a Y374C mutant FGFRl polypeptide (SEQ ID NO: 12). Such a polynucleotide is the product of alternative splicing of the human FGFRl gene. SEQ ID NO: 15 is a cDNA sequence representing an alternatively-spliced transcript of FGFRl, additionally having the exon 10 Al 115-?>G1115 mutation and therefore encoding the Y374C FGFRl mutant polypeptide shown in SEQ ID NO: 12.

l-PH/1977697.1 29 In another embodiment of the invention, the polypeptide of SEQ ID NO:2 is encoded by the polynucleotide set forth in SEQ ID NO:3. Specifically, SEQ ID NO:3 is an FGFRl polynucleotide comprising an Al 115->G1115 mutation and a Cl 116-^T1116 mutation. Due to the degeneracy of the genetic code, the polynucleotide set forth in SEQ ID NO: 3 encodes the Y372C polypeptide set forth in SEQ ID NO:2. The polynucleotide of SEQ ID NO:3 should therefore be understood to be as much a feature of the present invention as is the polynucleotide set forth in SEQ ID NO:l, and all discussions, applications, and embodiments of the present invention disclosed herein should be understood to apply with equal force to the polynucleotide set forth in SEQ ID NO:3. In another embodiment of the present invention, an isolated polynucleotide is provided, wherein the polynucleotide encodes a Y374C mutant FGFRl polypeptide (SEQ ID NO: 12). Such a polynucleotide is the product of alternative splicing of the human FGFRl gene. SEQ ID NO: 16 is a cDNA sequence representing an alternatively-spliced transcript of FGFRl, additionally having the exon 10 Al 115- G1115 and Cl 116->T1116 mutations and therefore encoding the Y374C FGFRl mutant polypeptide shown in SEQ ID NO: 12.

The present invention should not be construed as being limited solely to the nucleic and amino acid sequences disclosed herein. Once armed with the present invention, it is readily apparent to one skilled in the art that other nucleic acids encoding mutant FGFRl proteins can be obtained by following the procedures described herein in the experimental details section for the generation of other mammalian mutant FGFRl nucleic acids encoding mutant FGFRl polypeptides as disclosed herein (e.g., site-directed mutagenesis, frame shift mutations, and the like), and procedures that are well-known in the art or to be developed. Further, any other number of procedures may be used for the generation of derivative or variant forms of mutant FGFRl using recombinant DNA methodology well known in the art such as, for example, that described in Sambrook et al. (1989, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory Press, New York) and Ausubel et al. (1997, Current Protocols in Molecular Biology, Green & Wiley, New York).

Procedures for the introduction of amino acid changes in a protein or polypeptide by altering the DNA sequence encoding the polypeptide are well known

l-PH/1977697.1 30 in ne art and are also^'described in Sambrook et al. (1989, supra); Ausubel et al. (1997, supra).

The determination of percent identity between two nucleotide or amino acid sequences can be accomplished using a mathematical algorithm. For example, a mathematical algorithm useful for comparing two sequences is the algorithm of

Karlin and Altschul (1990, Proc. Natl. Acad. Sci. USA 87:2264-2268), modified as in Karlin and Altschul (1993, Proc. Natl. Acad. Sci. USA 90:5873-5877). This algorithm is incorporated into the NBLAST and XBLAST programs of Altschul, et al. (1990, J. Mol. Biol. 215:403-410), and can be accessed, for example at the National Center for Biotechnology Information (NCBI) world wide web site having the universal resource locator <<http://www.ncbi.nlm.nih.gov/BLAST/>>. BLAST nucleotide searches can be performed with the NBLAST program (designated "blastn" at the NCBI web site), using the following parameters: gap penalty = 5; gap extension penalty = 2; mismatch penalty = 3; match reward = 1; expectation value 10.0; and word size = 11 to obtain nucleotide sequences homologous to a nucleic acid described herein. BLAST protein searches can be performed with the XBLAST program (designated "blastn" at the NCBI web site) or the NCBI "blastp" program, using the following parameters: expectation value 10.0, BLOSUM62 scoring matrix to obtain amino acid sequences homologous to a protein molecule described herein. To obtain gapped alignments for comparison purposes, Gapped BLAST can be utilized as described in Altschul et al. (1997, Nucleic Acids Res. 25:3389-3402). Alternatively, PSI-Blast or PHI-Blast can be used to perform an iterated search which detects distant relationships between molecules (Id.) and relationships between molecules which share a common pattern. When utilizing BLAST, Gapped BLAST, PSI-Blast, and PHI-Blast programs, the default parameters of the respective programs (e.g., XBLAST and NBLAST) can be used. See <<http://www.ncbi.nlm.nih.gov>>.

In another aspect, a nucleic acid useful in the methods and compositions of the present invention and encoding a mutant FGFRl polypeptide may have at least one nucleotide inserted into the naturally-occurring nucleic acid sequence. Alternatively, an additional mutant FGFRl polynucleotide may have at least one nucleotide deleted from the naturally-occurring nucleic acid sequence. Further, a mutant FGFRl nucleic acid useful in the invention may have both a

l-PH/1977697.1 1 nucleotide insertion and a nucleotide deletion present in a single nucleic acid sequence encoding the mutant FGFRl polypeptide.

The invention includes a nucleic acid encoding a mammalian mutant FGFRl wherein a nucleic acid encoding a tag polypeptide is covalently linked thereto. That is, the invention encompasses a chimeric nucleic acid wherein the nucleic acid sequence encoding a tag polypeptide is covalently linked to the nucleic acid encoding a mutant FGFRl polypeptide. Such tag polypeptides are well known in the art and include, for instance, green fluorescent protein (GFP), myc, myc-pyruvate kinase (myc-PK), His₆, maltose biding protein (MBP), an influenza virus hemagglutinin tag polypeptide, a flag tag polypeptide (FLAG), a V5 tag, and a glutathione-S-transferase (GST) tag polypeptide. However, the invention should in no way be construed to be limited to the nucleic acids encoding the above-listed tag polypeptides. Rather, any nucleic acid sequence encoding a polypeptide which may function in a manner substantially similar to these tag polypeptides should be construed to be included in the present invention.

The nucleic acid comprising a nucleic acid encoding a tag polypeptide can be used to localize mutant FGFRl within a cell, a tissue, and/or a whole organism (e.g., a mammalian embryo), detect mutant FGFRl secreted from a cell, and to study the role(s) of mutant FGFRl in a cell. Further, addition of a tag polypeptide facilitates isolation and purification of the "tagged" protein such that the proteins of the invention can be produced and purified readily.

Antisense molecules and their use for inhibiting gene expression are well known in the art (see, e.g., Cohen, 1989, In: Oligodeoxyribonucleotides, Antisense Inhibitors of Gene Expression, CRC Press). Antisense nucleic acids are DNA or RNA molecules that are complementary to at least a portion of a specific mRNA molecule (Weintraub, 1990, Scientific American 262:40). In the cell, antisense nucleic acids hybridize to the corresponding mRNA, forming a double- stranded molecule thereby inhibiting the translation of genes.

The use of antisense methods to inhibit the translation of genes is known in the art, and is described, for example, in Marcus-Sakura (1988, Anal.

Biochem. 172:289). Such antisense molecules may be provided to the cell via genetic

l-PH/1977697.1 32 expression using DNA encoding the antisense molecule as taught by Inoue (1993, U.S. Patent No. 5,190,931).

Alternatively, antisense molecules can be produced synthetically and then provided to the cell. An antisense molecule useful for inhibiting gene expression is preferably one which is 10 consecutive nucleotides in length, more preferably, one which is 20 consecutive nucleotides in length, more preferably, one which is 30 consecutive nucleotides in length, more preferably, one which is 50 consecutive nucleotides in length, more preferably, one which is 100 consecutive nucleotides in length, even more preferably, one which is 150 consecutive nucleotides in length, an most preferably, one which is about 200 consecutive nucleotides in length. Antisense oligomers of between about 10 to about 100, and more preferably about 15 to about 50 nucleotides, are preferred, since they are easily synthesized and introduced into a target cell. Synthetic antisense molecules contemplated by the invention include oligonucleotide derivatives known in the art which, have improved biological activity compared to unmodified oligonucleotides (see Cohen, supra; Tullis, 1991, U.S. Patent No. 5,023,243, incorporated by reference herein in its entirety).

Ribozymes and their use for inhibiting gene expression are also well known in the art (see, e.g., Cech et al., 1992, J. Biol. Chem. 267:17479-17482; Hampel et al., 1989, Biochemistry 28:4929-4933; Eckstein et al., International Publication No. WO 92/07065; Altman et al, U.S. Patent No. 5,168,053, incoiporated by reference herein in its entirety). Ribozymes are RNA molecules possessing the ability to specifically cleave other single-stranded RNA in a manner analogous to DNA restriction endonucleases. Through the modification of nucleotide sequences encoding these RNAs, molecules can be engineered to recognize specific nucleotide sequences in an RNA molecule and cleave it (Cech, 1988, J. Amer. Med. Assn. 260:3030). A major advantage of this approach is that, because they are sequence- specific, only mRNAs with particular sequences are inactivated.

There are two basic types of ribozymes, namely, Tetrahymena-type (Hasselhoff, 1988, Nature 334:585) and hammerhead-type. Tetrahymena-type ribozymes recognize sequences, which are four bases in length, while hammerhead- type ribozymes recognize base sequences 11-18 bases in length. The longer the sequence, the greater the likelihood that the sequence will occur exclusively in the

l-PH/1977697.1 33 target n J A species. Consequently, hammerhead-type ribozymes are preferable to Tetrahymena-type ribozymes for inactivating specific mRNA species, and 18-base recognition sequences are preferable to shorter recognition sequences, which may occur randomly within various unrelated mRNA molecules. Ribozymes useful for inhibiting the expression of FGFRl may be designed by incorporating target sequences into the basic ribozyme structure which are complementary to the mRNA sequence of the FGFRl encoded by FGFRl or having at least about 80% homology to at least one of SEQ ID NO:l. Ribozymes targeting FGFRl can be synthesized using commercially available reagents (Applied Biosystems, Inc., Foster City, CA) or they may be genetically expressed from DNA encoding them.

Vectors

In other related aspects, the invention includes an isolated nucleic acid encoding a mammalian FGFRl operably linked to a nucleic acid comprising a promoter/regulatory sequence such that the nucleic acid is preferably capable of directing expression of the protein encoded by the nucleic acid. Thus, the invention encompasses expression vectors and methods for the introduction of exogenous DNA into cells with concomitant expression of the exogenous DNA in the cells such as those described, for example, in Sambrook et al. (1989, Molecular Cloning: A

Laboratory Manual, Cold Spring Harbor Laboratory, New York), and in Ausubel et al. (1997, Current Protocols in Molecular Biology, John Wiley & Sons, New York).

Expression of FGFRl, either alone or fused to a detectable tag polypeptide, in cells which either normally express normal FGFRl, may be accomplished by generating a plasmid, viral, or other type of vector comprising the desired nucleic acid operably linked to a promoter/regulatory sequence which serves to drive expression of the protein, with or without tag, in cells in which the vector is introduced. Many promoter/regulatory sequences useful for driving constitutive expression of a gene are available in the art and include, but are not limited to, for example, the cytomegalovirus immediate early promoter enhancer sequence, the

SV40 early promoter, both of which were used in the experiments disclosed herein, as well as the Rous sarcoma virus promoter, and the like. Moreover, inducible and

l-PH/1977697.1 34 ^' tissue specific expression of the nucleic acid encoding FGFRl may be accomplished by placing the nucleic acid encoding FGFRl, with or without a tag, under the control of an inducible or tissue specific promoter/regulatory sequence. Examples of tissue specific or inducible promoter/regulatory sequences which are useful for his purpose include, but are not limited to the MMTV LTR inducible promoter, and the SV40 late enhancer/promoter. In addition, promoters which are well known in the art which are induced in response to inducing agents such as metals, glucocorticoids, and the like, are also contemplated in the invention. Thus, it will be appreciated that the invention includes the use of any promoter/regulatory sequence, which is either known or unknown, and which is capable of driving expression of the desired protein operably linked thereto.

Expressing FGFRl using a vector allows the isolation of large amounts of recombinantly produced protein. Further, where the expression of FGFRl causes a disease, disorder, or condition associated with such expression, the expression of soluble FGFRl driven by a promoter/regulatory sequence can provide useful therapeutics including, but not limited to, a competitive inhibitor for FGFRl binding partners. A disease, disorder or condition associated with FGFRl, for which administration of FGFRl can be useful can include, but is not limited to, hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, fibrous dysplasia, and HBD, and the like.

The invention also includes methods relating to decreasing FGFRl expression, protein level, and/or activity, since decreasing FGFRl expression, and/or activity can be useful in providing effective therapeutics. One of skill in the art will understand that decreasing FGFRl expression can be achieved using antisense or ribozyme technology, as described elsewhere herein.

Selection of any particular plasmid vector or other DNA vector is not a limiting factor in this invention and a wide plethora of vectors are well-known in the art. Further, it is well within the skill of the artisan to choose particular promoter/regulatory sequences and operably link those promoter/regulatory sequences to a DNA sequence encoding a desired polypeptide. Such technology is well known

l-PH/1977697.1 35 in e art arid is^''Hescπhed7for example, in Sambrook et al. (1989, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, New York), and in Ausubel et al. (1997, Current Protocols in Molecular Biology, John Wiley & Sons, New York). The invention thus includes a vector comprising an isolated nucleic acid encoding an FGFRl . The incorporation of a desired nucleic acid into a vector and the choice of vectors is well-known in the art as described in, for example, Sambrook et al. (1989, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, New York), and in Ausubel et al. (1997, Current Protocols in Molecular Biology, John Wiley & Sons, New York). The invention also includes cells, viruses, proviruses, and the like, containing such vectors. Methods for producing cells comprising vectors and/or exogenous nucleic acids are well-known in the art. See, for example, Sambrook et al. (1989, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, New York), and in Ausubel et al. (1997, Current Protocols in Molecular Biology, John Wiley & Sons, New York).

The nucleic acids encoding FGFRl may be cloned into various plasmid vectors. However, the present invention should not be construed to be limited to plasmids or to any particular vector. Instead, the present invention should be construed to encompass a wide plethora of vectors which are readily available and/or well-known in the art.

One of ordinary skill would appreciate, based upon the disclosure provided herein, that a "knock- in" or "knock-out" vector of the invention comprises at least two sequences homologous to two portions of the nucleic acid which is to be replaced or deleted, respectively. The two sequences are homologous with sequences that flank the gene; that is, one sequence is homologous with a region at or near the 5' portion of the coding sequence of the nucleic acid encoding normal FGFRl and the other sequence is further downstream from the first. One skilled in the art would appreciate, based upon the disclosure provided herein, that the present invention is not limited to any specific flanking nucleic acid sequences. Instead, the targeting vector may comprise two sequences which remove some or all of, for example, normal FGFRl (i.e., a "knock-out" vector) or which insert (i.e., a "knock-in" vector) a nucleic acid encoding FGFRl, or a fragment thereof, from or into a mammalian

l-PH/1977697.1 3 genome, respectively. The crucial feature of the targeting vector is that it comprise sufficient portions of two sequences located towards opposite, i.e., 5' and 3', ends of the normal FGFRl open reading frame (ORF) in the case of a "knock-out" vector, to allow deletion/insertion by homologous recombination to occur such that all or a portion of the nucleic acid encoding normal FGFRl is deleted from a location on a mammalian chromosome.

The design of transgenes and knock-in and knock-out targeting vectors is well-known in the art and is described in standard treatises such as Sambrook et al. (1989, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, New York), and in Ausubel et al. (1997, Current Protocols in Molecular Biology,

John Wiley & Sons, New York), and the like. The upstream and downstream portions flanking or within the FGFRl coding region to be used in the targeting vector may be easily selected based upon known methods and following the teachings disclosed herein based on the disclosure provided herein including the nucleic and amino acid sequences of mammalian FGFRl and mutant FGFRl. Armed with these sequences, one of ordinary skill in the art would be able to construct the transgenes and knockout vectors of the invention.

Trans genie animals The invention further includes a non-human transgenic mammal the genome of which lacks a functional form of FGFRl, and thereby eliminates the biological activity of FGFRl. In one example, the non-human transgenic mammal comprises an exogenous nucleic acid inserted into a desired site in the genome thereof thereby deleting the coding region FGFRl, i.e., a knock-out transgenic mammal. Such animals provide a useful model to study human disease states associated with mutations in FGFRl. Preferably, the transgenic mammal is a mouse. A mouse in which the function of FGFRl has been knocked out would either have a hyperphosphatemic phenotype or a non phosphate phenotype.

Further, the invention includes a transgenic non-human mammal wherein an exogenous nucleic acid encoding FGFRl is inserted into a site the genome, i.e., a "knock-in" transgenic mammal. The knock-in transgene inserted may comprise various nucleic acids encoding, for example, a tag polypeptide, a

l-PH/1977697.1 37 ^" promoter/regulatory region operably linked to the nucleic acid encoding FGFRl not normally present in the cell or not typically operably linked to FGFRl . Expression of the FGFRl knock-in transgene likely cause hypophosphatemia in the animal, resulting in a phenotype which resembles CFDH, or oncogenic hypophosphatemic osteomalacia and ADHR. Both wild-type and mutant forms of FGFRl can be inserted into the genome of the mammal. In particular, insertion of the mutants disclosed herein would produce a more stable form of FGFRl and may therefore result in a prolonged or enhanced hypophosphatemic condition in the animal.

The generation of the non-human transgenic mammal of the invention is preferably accomplished using the method which is now described. However, the invention should in no way be construed as being limited solely to the use of this method, in that, other methods can be used to generate the desired knock-out mammal.

In the preferred method of generating a non-human transgenic mammal, ES cells are generated comprising the transgene of the invention and the cells are then used to generate the knock-out animal essentially as described in Nagy and Rossant (1993, In: Gene Targeting, A Practical Approach, pp.146-179, Joyner ed., IRL Press). ES cells behave as normal embryonic cells if they are returned to the embryonic environment by injection into a host blastocyst or aggregate with blastomere stage embryos. When so returned, the cells have the full potential to develop along all lineages of the embryo. Thus, it is possible, to obtain ES cells, introduce a desired DNA therein, and then return the cell to the embryonic environment for development into mature mammalian cells, wherein the desired DNA may be expressed. Precise protocols for the generation of transgenic mice are disclosed in

Nagy and Rossant (1993, In: Gene Targeting, A Practical Approach, Joyner ed. IRL Press, pp. 146-179). and are therefore not repeated herein. Transfection or transduction of ES cells in order to introduce the desired DNA therein is accomplished using standard protocols, such as those described, for example, in Sambrook et al. (1989, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, New York), and in Ausubel et al. (1997, Current Protocols in Molecular Biology, John Wiley & Sons, New York). Preferably, the desired DNA

l-PH/1977697.1 3g contained within the transgene of the invention is electroporated into ES cells, and the cells are propagated as described in Soriano et al. (1991, Cell 64:693-702).

Introduction of an isolated nucleic acid into the fertilized egg of the mammal is accomplished by any number of standard techniques in transgenic technology (Hogan et al, 1986, Manipulating the Mouse Embryo: A Laboratory Manual, Cold Spring Harbor, NY). Most commonly, the nucleic acid is introduced into the embryo by way of microinjection.

Once the nucleic acid is introduced into the egg, the egg is incubated for a short period of time and is then transferred into a pseudopregnant mammal of the same species from which the egg was obtained as described, for example, in Hogan et al. (1986, Manipulating the Mouse Embryo: A Laboratory Manual, Cold Spring Harbor, NY). Typically, many eggs are injected per experiment, and approximately two-thirds of the eggs survive the procedure. About twenty viable eggs are then transferred into pseudopregnant animals, and usually four to ten of the viable eggs so transferred will develop into live pups.

Any mammalian FGFRl gene may be used in the methods described herein to produce a transgenic mammal or a transgenic cell harboring a transgene comprising a deletion of all or part of that FGFRl gene. Preferably, an FGFRl gene such as, e.g., human FGFRl (SEQ ID NO: 4) isolated polynucleotide, is also used. The transgenic mammal of the invention can be any species of mammal. Thus, the invention should be construed to include generation of transgenic mammals encoding the chimeric nucleic acid, which mammals include mice, hamsters, rats, rabbits, pigs, sheep and cattle. The methods described herein for generation of transgenic mice can be analogously applied using any mammalian species. Preferably, the transgenic mammal of the invention is a rodent and even more preferably, the transgenic mammal of the invention is a mouse. By way of example, Lukkarinen et al. (1997, Stroke 28:639-645), teaches that gene constructs which enable the generation of transgenic mice also enable the generation of other transgenic rodents, including rats. Similarly, nullizygous mutations in a genetic locus of an animal of one species can be replicated in an animal of another species having a genetic locus highly homologous to the first species.

l-PH/1977697.1 39 '^"Tό identify the transgenic mammals of the invention, pups are examined for the presence of the isolated nucleic acid using standard technology such as Southern blot hybridization, PCR, and/or RT-PCR. Expression of the nucleic acid in the cells and in the tissues of the mammal is also assessed using ordinary technology described herein.

Cells obtained from the transgenic mammal of the invention, which are also considered "transgenic cells" as the term is used herein, encompass cells such as those obtained from the FGFRl (+/-) and (-/-) transgenic non-human mammal described elsewhere herein, are useful systems for modeling diseases and symptoms of mammals which are believed to be associated with altered levels of FGFRl expression.

Particularly suitable are cells derived from a tissue of the non-human knock-out or knock-in transgenic mammal described herein, wherein the transgene comprising the FGFRl gene is expressed or inhibits expression of FGFRl in various tissues. By way of example, cell types from which such cells are derived include fibroblasts and endothelial cells of (1) the FGFRl (+/+), (+/-) and (-/-) non-human transgenic liveborn mammal, (2) the FGFRl (+/+), (-/-) or (+/-) fetal animal, and (3) placental cell lines obtained from the FGFRl (+/+), (-/-) and (+/-) fetus and liveborn mammal. In one aspect of the present invention, a transgenic animal of the present invention may be a knock-out mouse. In one embodiment of the invention, a transgenic mouse is a kidney-specific knock-out mouse. In another embodiment of the invention, a transgenic mouse is an intestine-specific knock-out mouse. In yet another embodiment of the present invention, a transgenic mouse is a bone-specific (osteoblast-specific) knock-out mouse, and such a transgenic mouse may be driven by a promoter, including, but not limited to an osteocalcin or collagen promoter. These promoters, and others of like ilk are well-known to those of skill in the art.

Isolated polypeptides

The invention also includes an isolated polypeptide comprising a mammalian FGFRl molecule. Further, the present invention includes an isolated polypeptide comprising a mammalian mutant FGFRl molecule. Preferably, the isolated polypeptide comprising a mammalian mutant FGFRl molecule is at least

l-PH/1977697.1 40 ^•aboιit""99^'.8% homologous ^''to a polypeptide having the amino acid sequence of SEQ ID NO:2, or some fragment thereof. Preferably, the isolated polypeptide is about 99.9% homologous to SEQ ID NO:2, or some fragment thereof. Most preferably, the isolated polypeptide comprising a mutant FGFRl molecule is SEQ ID NO:2. The present invention also provides for analogs of proteins or peptides which comprise a FGFRl molecule as disclosed herein. Analogs may differ from naturally occurring proteins or peptides by conservative amino acid sequence differences or by modifications which do not affect sequence, or by both. For example, conservative amino acid changes may be made, which although they alter the primary sequence of the protein or peptide, do not normally alter its function. Conservative amino acid substitutions typically include substitutions within the following groups: glycine, alanine; valine, isoleucine, leucine; aspartic acid, glutamic acid; asparagine, glutamine; serine, threonine; lysine, arginine; phenylalanine, tyrosine. Modifications (which do not normally alter primary sequence) include in vivo, or in vitro, chemical derivatization of polypeptides, e.g., acetylation, or carboxylation. Also included are modifications of glycosylation, e.g., those made by modifying the glycosylation patterns of a polypeptide during its synthesis and processing or in further processing steps; e.g., by exposing the polypeptide to enzymes which affect glycosylation, e.g., mammalian glycosylating or deglycosylating enzymes. Also embraced are sequences which have phosphorylated amino acid residues, e.g., phosphotyrosine, phosphoserine, or phosphothreonine.

Also included are polypeptides which have been modified using ordinary molecular biological techniques so as to improve their resistance to proteolytic degradation or to optimize solubility properties or to render them more suitable as a therapeutic agent. Analogs of such polypeptides include those containing residues other than naturally occurring L-amino acids, e.g., D-amino acids

l-PH/1977697.1 A\ ' or non-naturally occurring synthetic ammo acids. The peptides of the invention are not limited to products of any of the specific exemplary processes listed herein.

The present invention should also be construed to encompass "derivatives," and "variants" of the peptides of the invention (or of the DNA encoding the same) which derivatives and variants are mutant FGFRl peptides which are altered in one or more amino acids (or, when referring to the nucleotide sequence encoding the same, are altered in one or more base pairs) such that the resulting peptide (or DNA) is not identical to the sequences recited herein, but has the same biological property as the peptides disclosed herein, in that the peptide has biological/biochemical properties of the FGFRl peptide of the present invention. The invention also encompasses fragments of FGFRl polypeptides. The invention further encompasses fragments of mutant FGFRl polypeptides which necessarily contain the "mutated" portion of the full-length mutant FGFRl polypeptide. One of skill in the art would recognize a fragment of full-length mutant FGFRl that contains one or more of the mutant, or "non-wild type" amino acids. In an embodiment of the present invention, a fragment of full-length mutant FGFRl contains cysteine 372 of the Y372C mutant FGFRl set forth in SEQ ID NO:2. In another embodiment of the present invention, a fragment of full-length mutant FGFRl contains cysteine 374 of the Y374C mutant FGFRl set forth in SEQ ID NO: 12. It will be understood that fragments of FGFRl of the present invention encompass those fragments containing more than one mutation of a mutant FGFRl containing more than one mutation.

The present invention should also be construed to encompass soluble FGFRl . Soluble FGFRl may be readily prepared by one of skill in the art, using well-known molecular biology and/or protein chemistry techniques. By way of several non-limiting examples, FGFRl may be rendered soluble by removal of the intracellular domain, the trans-membrane domain, or both such domains. Further, soluble FGFRl may be prepared by removal of portions of the extracellular domain, using recombinant DNA and/or protein engineering methods known to one of skill in the art. Further still, the present invention should be construed to encompass soluble FGFRl that has been prepared by addition of one or more amino acids to the soluble polypeptide, either by molecular biology and/or protein chemistry techniques known

l-PH/ 1977697 1 42 ^! to one of skill in" the" art^"" Further, soluble FGFRl may be produced by a combination of additions and deletions of amino acids to the FGFRl polypeptide, either by molecular biology and/or protein chemistry techniques known to one of skill in the art. For example, a soluble FGFRl of the present invention may be produced by deleting the intercellular and transmembrane domains, and by addition of a solubilizing peptide tag to the remaining FGFRl molecule. Such a peptide tag may be added by creation of a fusion protein with the FGFRl fragment and the solubilizing peptide, as described elsewhere herein.

In one embodiment of the present invention, a soluble FGFRl may be an FGFRl chimera, which chimera is comprised of an FGFRl molecule from which the transmembrane domain has been deleted and an Fc portion of an immunoglobulin molecule. Such a soluble FGFRl chimera may also have the property of binding an FGF molecule. Analysis of an interaction between an Fc-FGFRl chimera and an FGF, such as a binding interaction, can be assessed by any one of numerous methods known to one of skill in the art, including, but not limited to specfroscopic techniques, including surface plasmon resonance, fluorescence spectroscoy, fluorescence resonant energy transfer, fluorescence quenching, absorbance spectroscopy, nuclear magnetic resonance, electron paramagnetic resonance, mass spectrometry, and x-ray spectroscopy. Analysis of the interaction between an Fc-FGFRl chimera and an FGF can also be assessed by chromatographic methods, electrophoretic methods, calorimetric methods, analytical ultracentrifugation, ligand competition assays, and affinity assays.

One of skill in the art will further understand that any analytical technique useful for the analysis of an interaction between an Fc-FGFRl chimera and an FGF is equally applicable to the interaction of an Fc-FGFRl chimera with any other (i.e., "non-FGF") ligand. Further, one of skill in the art will also understand that any analytical technique useful for the analysis of an interaction between an Fc- FGFRl chimera and an FGF is equally applicable to the interaction of any FGFRl with any ligand, and the use of such analytical techniques for analysis of any of the above-mentioned interactions is encompassed by the present invention.

In one aspect of the invention, the soluble FGFRl is created using a polynucleotide encoding wild type FGFRl. In another aspect of the invention,

l-PH/1977697.1 43 ^•• sσiuD e r utfKi is produced using a polynucleotide encoding a mutant FGFRl . In yet another aspect of the present invention, soluble FGFRl is produced using a polynucleotide encoding Y372C FGFRl. In yet another aspect of the present invention, soluble FGFRl is produced using a polynucleotide encoding Y374C FGFRl.

The skilled artisan would understand, based upon the disclosure provided herein, that mutant FGFRl biological activity encompasses, but is not limited to, the ability of a molecule or compound to be expressed in a mammalian cell, to be detected in a mammalian cell, to be secreted from a cell, to be anchored to a cell, and the like. "Mutant FGFRl activity" and "biological activity of mutant

FGFRl" encompasses the effects of mutant FGFRl, which includes most, if not all of the effects of wild type FGFRl as well as the clinical effects, manifestations, and sequelae of hypophosphatemic disorders, such as CFDH. Mutant FGFRl biological activity mediates, is associated with, or both, inter alia, CFDH and a hypophosphatemic condition.

Substantially pure protein isolated and obtained as described herein may be purified by following known procedures for protein purification, wherein an immunological, enzymatic or other assay is used to monitor purification at each stage in the procedure. Protein purification methods are well known in the art, and are described, for example in Deutscher et al. (ed., 1990, Guide to Protein Purification, Harcourt Brace Jovanovich, San Diego).

IV. Recombinant cells

The invention includes a recombinant cell comprising, inter alia, an isolated nucleic acid encoding FGFRl, an antisense nucleic acid complementary thereto, a nucleic acid encoding an antibody that specifically binds FGFRl, and the like. In one aspect, the recombinant cell can be transiently transfected with a plasmid encoding a portion of the nucleic acid encoding FGFRl. The nucleic acid need not be integrated into the cell genome nor does it need to be expressed in the cell. Moreover, the cell may be a prokaryotic or a eukaryotic cell and the invention should not be construed to be limited to any particular cell line or cell type. Cells useful in the

l-PH/1977697.1 44 ^•''pMsenVmventioii include" but are not limited to HEK293 cells, opossum kidney (OK) cells, and COS cells.

OK cells, by way of a non-limiting example, are useful in the present invention, as phosphate transport can easily be observed in a transfected OK cell. Briefly, to quantify phosphate transport, an OK cell is transfected with an FGFR vector construct of the present invention. Transfection of an OK cell with an FGFR construct is confirmed using Western blot analysis with anti-FGFRl antibodies and transfection efficiency is assessed by comparison of FGFR construct-containing cells with cell transfected in parallel with a beta-galactosidase reporter construct. The OK cells are then incubated for varying times, some cells in the presence of FGF23 and some cells in the absence of FGF23, at which point, phosphate uptake is initated for all incubated cells. Total phosphate analysis, using one of many methods known to one of skill in the art, is then used to quantitate phosphate transport.

The invention includes a eukaryotic cell which, when the isolated nucleic acid of the invention is introduced therein and the protein encoded by the desired isolated nucleic acid is expressed therefrom where it was not previously present or expressed in the cell or where it is now expressed at a level or under circumstances different than that before the transgene was introduced, a benefit is obtained. Such a benefit may include the fact that there has been provided a system wherein the expression of the desired isolated nucleic acid can be studied in vitro in the laboratory or in a mammal in which the cell resides, a system wherein cells comprising the introduced isolated nucleic acid can be used as research, diagnostic and therapeutic tools, or a system wherein animal or other organism models are generated which are useful for the development of new diagnostic and therapeutic tools for selected disease states in those organisms or in humans.

A cell expressing an isolated nucleic acid encoding FGFRl can be used to provide FGFRl to a cell, tissue, or whole mammal where a higher level of FGFRl can be useful to treat or alleviate a disease, disorder or condition. Such diseases, disorders or conditions can include, but are not limited to, mild renal insufficiency, tumoral calcinosis and the like. Other diseases, disorders or conditions that may be treated by a cell expressing an isolated nucleic acid encoding FGFRl include, but are not limited to craniofacial dysplasia with hypophosphatemia, X-

l-PH/ 1977697.1 45 • ιmκed'nypopnσspnatemiC"rιcK;ets, autosomal dominant Hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia.

One skilled in the art would appreciate, based upon this disclosure, that cells comprising decreased levels of FGFRl protein, decreased levels of FGFRl activity, or both, include, but are not limited to, cells expressing inhibitors of FGFRl expression (e.g., antisense or ribozyme molecules, synthetic antibodies or intrabodies).

Methods and compositions useful for maintaining mammalian cells in culture are well known in the art, wherein the mammalian cells are obtained from a mammal including, but not limited to, cells obtained from a mouse, a rat, a human, and the like.

The recombinant cell of the invention, wherein the cell has been engineered such that it does not express FGFRl, or expresses FGFRl, can also be used in ex vivo and in vivo cell therapies where either a mammal's own cells or those of a syngeneic matched donor are recombinantly engineered as described elsewhere herein (e.g., by insertion of an antisense nucleic acid or a knock-out vector such that FGFRl expression and/or protein levels are thereby reduced in the recombinant cell), and the recombinant cell is administered to the recipient mammal. In this way, recombinant cells that express FGFRl at a reduced level can be administered to a mammal whose own cells express FGFRl having increased activity, thereby treating or alleviating a disease, disorder or condition associated with or mediated by FGFRl expression as disclosed elsewhere herein.

V. Antibodies Also included is an antibody that specifically binds mutant FGFRl, a mutant FGFRl cleavage product, or fragments thereof. In one embodiment, the antibody is directed to human Y372C FGFRl comprising the amino acid sequence set forth in SEQ ID NO:2. In another embodiment, the antibody is directed to human Y374C FGFRl comprising the amino acid sequence set forth in SEQ ID NO: 12. Antibodies of the invention also encompass those antibodies that preferentially bind mutant FGFRl over wild type FGFRl. Differential binding of such mutant FGFRl -specific antibodies can be ascertained using methods well-known

l-PH/1977697.1 A ^■to 'brie¹¹ of still itfth irtr Sϊich methods include, but are not limited to Western Blot analysis, ELISA, affinity chromatography, gel filtration, immunoprecipitation, immunohistochemical staining, surface plasmon resonance, mass spectrometry, and electrophoretic mobility shift assays. In one embodiment, the antibody is directed to human Y372C FGFRl comprising the amino acid sequence set forth in SEQ ID NO:2, and such an antibody binds to Y372C FGFRl but not to wild type FGFRl . In another embodiment, the antibody is directed to human Y374C FGFRl comprising the amino acid sequence set forth in SEQ ID NO: 12, and such an antibody binds to Y374C FGFRl but not to wild type FGFRl. The generation of polyclonal antibodies is accomplished by inoculating the desired animal with the antigen and isolating antibodies which specifically bind the antigen therefrom using standard antibody production methods such as those described in, for example, Harlow et al. (1988, In: Antibodies, A Laboratory Manual, Cold Spring Harbor, NY). Such techniques include immunizing an animal with a chimeric protein comprising a portion of another protein such as a maltose binding protein or glutathione (GSH) tag polypeptide portion, and/or a moiety such that the FGFRl portion is rendered immunogenic (e.g., mutant FGFRl conjugated with keyhole limpet hemocyanin, KLH) and a portion comprising the respective rodent and/or human FGFRl amino acid residues. The chimeric proteins are produced by cloning the appropriate nucleic acids encoding mutant FGFRl (e.g., SEQ ID NO: 1) into a plasmid vector suitable for this purpose, such as but not limited to, pMAL-2 or pCMX. Other methods of producing antibodies that specifically bind mutant FGFRl and portions thereof are detailed in Matthews et al. (2000, J. Biol. Chem. 275: 22695- 22703). However, the invention should not be construed as being limited solely to polyclonal antibodies that bind a full-length mutant FGFRl. Rather, the invention should be construed to include other antibodies, as that term is defined elsewhere herein, to human mutant FGFRl, or portions thereof. Further, the present invention should be construed to encompass antibodies that, among other things, bind to mutant FGFRl and are able to bind mutant FGFRl present on Western blots, in immunohistochemical staining of tissues thereby localizing mutant FGFRl in the

l-PH/1977697.1 47 ''^' tlsls ^'ei ald iή'lniiϊϊUrisfluorescence microscopy of a cell transiently or stably transfected with a nucleic acid encoding at least a portion of mutant FGFRl.

One skilled in the art would appreciate, based upon the disclosure provided herein, that the antibody can specifically bind with any portion of the protein and the full-length protein can be used to generate antibodies specific therefor. However, the present invention is not limited to using the full-length protein as an immunogen. Rather, the present invention includes using an immunogenic portion of the protein to produce an antibody that specifically binds with human wild type or mutant FGFRl. That is, the invention includes immunizing an animal using an immunogenic portion, or antigenic determinant, of the wild type or mutant FGFRl protein, for example, the epitope comprising the cleavage site, or a new antigenic site produced by proteolytic cleavage.

The antibodies can be produced by immunizing an animal such as, but not limited to, a rabbit or a mouse, with a wild type or mutant FGFRl protein, or a portion thereof, or by immunizing an animal using a protein comprising at least a portion of FGFRl, or a fusion protein including a tag polypeptide portion comprising, for example, a maltose binding protein tag polypeptide portion, covalently linked with a portion comprising the appropriate wild type or mutant FGFRl amino acid residues. One skilled in the art would appreciate, based upon the disclosure provided herein, that smaller fragments of these proteins can also be used to produce antibodies that specifically bind either wild type or mutant FGFRl .

Once armed with the sequence of FGFRl and the detailed analysis localizing the various epitopes and cleavage products of the protein, the skilled artisan would understand, based upon the disclosure provided herein, how to obtain antibodies specific for the various portions of a mammalian FGFRl polypeptide using methods well-known in the art or to be developed. Therefore, the skilled artisan would appreciate, based upon the disclosure provided herein, that the present invention encompasses antibodies that neutralize and/or inhibit mutant FGFRl activity (e.g., by inhibiting necessary FGFRl receptor/ligand interactions) which antibodies can recognize FGFRl or FGFRl cleavage products.

The invention should not be construed as being limited solely to the antibodies disclosed herein or to any particular immunogenic portion of the proteins

l-PH/1977697.1 48 f of -the'lnVentioή:':' Rame ^tne invention should be construed to include any antibody that binds to mutant FGFRl.

One skilled in the art would appreciate, based upon the disclosure provided herein, that the antibodies can be used to localize the relevant protein in a cell and to study the role(s) of the antigen recognized thereby in cell processes.

Moreover, the antibodies can be used to detect and or measure the amount of protein present in a biological sample using well-known methods such as, but not limited to, Western blotting and enzyme-linked immunosorbent assay (ELISA). Moreover, the antibodies can be used to immunoprecipitate and/or immuno-affinity purify their cognate antigen using methods well-known in the art. In addition, the antibody can be used to decrease the effective level of mutant FGFRl in a cell thereby inhibiting the effect(s) of mutant FGFRl in a cell. Thus, by administering the antibody to a cell or to the tissues of a mammal or to the mammal itself, the mutant FGFRl receptor/ligand interactions are therefore inhibited such that the typical effects of mutant FGFRl receptor/ligand interaction is also inhibited. One skilled in the art would understand that inhibiting mutant FGFRl receptor/ligand interactions using an anti-mutant FGFRl antibody can include, but is not limited to, therapeutic treatment for hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia and the like. The invention encompasses polyclonal, monoclonal, synthetic antibodies, and the like. One skilled in the art would understand, based upon the disclosure provided herein, that the crucial feature of the antibody of the invention is that the antibody bind specifically with mutant FGFRl. That is, the antibody of the invention recognizes mutant FGFRl, or a fragment thereof (e.g., an immunogenic portion or antigenic determinant thereof), on Western blots, in immunostaining of cells, and immunoprecipitates mutant FGFRl using standard methods well-known in the art.

Monoclonal antibodies directed against full length or peptide fragments of a protein or peptide may be prepared using any well known monoclonal antibody preparation procedures, such as those described, for example, in Harlow et al. (1988, In: Antibodies, A Laboratory Manual, Cold Spring Harbor, NY) and in

l-PH/1977697.1 49 ^•' ltiszyns i' et ar χιyso";"Blθod, 72:109-115). Quantities of the desired peptide may also be synthesized using chemical synthesis technology. Alternatively, DNA encoding the desired peptide may be cloned and expressed from an appropriate promoter sequence in cells suitable for the generation of large quantities of peptide. Monoclonal antibodies directed against the peptide are generated from mice immunized with the peptide using standard procedures as referenced herein.

Nucleic acid encoding the monoclonal antibody obtained using the procedures described herein may be cloned and sequenced using technology which is available in the art, and is described, for example, in Wright et al. (1992, Critical Rev. Immunol. 12:125-168), and the references cited therein.

Further, the antibody of the invention may be "humanized" using the technology described in, for example, Wright et al. (1992, Critical Rev. Immunol. 12:125-168), and in the references cited therein, and in Gu et al. (1997, Thrombosis and Hematocyst 77:755-759). The present invention also includes the use of humanized antibodies specifically reactive with epitopes of mutant FGFRl. Such antibodies are capable of specifically binding mutant FGFRl, or a fragment thereof. The humanized antibodies of the invention have a human framework and have one or more complementarity determining regions (CDRs) from an antibody, typically, but not limited to a mouse antibody, specifically reactive with mutant FGFRl, or a fragment thereof. Thus, for example, humanized antibodies to mutant FGFRl are useful in the treatment of hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia and the like. When the antibody used in the invention is humanized, the antibody may be generated as described in Queen, et al. (U.S. Patent No. 6,180,370), Wright et al., (1992, Critical Rev. Immunol. 12:125-168) and in the references cited therein, or in Gu et al. (1997, Thrombosis and Hematocyst 77(4):755-759). The method disclosed in Queen et al. is directed in part toward designing humanized immunoglobulins that are produced by expressing recombinant DNA segments encoding the heavy and light chain complementarity determining regions (CDRs) from a donor immunoglobulin capable of binding to a desired antigen, such as mutant

l-PH/1977697.1 50 'FGFk'ϊ^l,^,iattacheiil^i!td^,B^'Ϊ^ 'segments encoding acceptor human framework regions. Generally speaking, the invention in the Queen patent has applicability toward the design of substantially any humanized immunoglobulin. Queen explains that the DNA segments will typically include an expression control DNA sequence operably linked to the humanized immunoglobulin coding sequences, including naturally- associated or heterologous promoter regions. The expression control sequences can be eukaryotic promoter systems in vectors capable of transforming or transfecting eukaryotic host cells or the expression control sequences can be prokaryotic promoter systems in vectors capable of transforming or transfecting prokaryotic host cells. Once the vector has been incorporated into the appropriate host, the host is maintained under conditions suitable for high level expression of the introduced nucleotide sequences and as desired the collection and purification of the humanized light chains, heavy chains, light/heavy chain dimers or intact antibodies, binding fragments or other immunoglobulin forms may follow (Beychok, Cells of Immunoglobulin Synthesis, Academic Press, New York, (1979), which is incorporated herein by reference).

Human constant region (CDR) DNA sequences from a variety of human cells can be isolated in accordance with well known procedures. Preferably, the human constant region DNA sequences are isolated from immortalized B-cells as described in WO87/02671, which is herein incorporated by reference. CDRs useful in producing the antibodies of the present invention may be similarly derived from DNA encoding monoclonal antibodies capable of binding to mutant FGFRl. Such humanized antibodies may be generated using well known methods in any convenient mammalian source capable of producing antibodies, including, but not limited to, mice, rats, rabbits, or other vertebrates. Suitable cells for constant region and framework DNA sequences and host cells in which the antibodies are expressed and secreted, can be obtained from a number of sources, for example, American Type Culture Collection, Manassas, VA.

In addition to the humanized antibodies discussed above, other modifications to native antibody sequences can be readily designed and manufactured utilizing various recombinant DNA techniques well known to those skilled in the art. Moreover, a variety of different human framework regions may be used singly or in

l-PH/1977697 1 5 \ combination as a "basis tbr numanizing antibodies directed to mutant FGFRl . In general, modifications of genes may be readily accomplished using a variety of well- known techniques, such as site-directed mutagenesis (Gillman and Smith, Gene, 8:81- 97 (1979); Roberts et al., 1987, Nature, 328:731-734). Alternatively, a phage antibody library may be generated. To generate a phage antibody library, a cDNA library is first obtained from mRNA which is isolated from cells, e.g., the hybridoma, which express the desired protein to be expressed on the phage surface, e.g., the desired antibody. cDNA copies of the mRNA are produced using reverse transcriptase. cDNA which specifies immunoglobulin fragments are obtained by PCR and the resulting DNA is cloned into a suitable bacteriophage vector to generate a bacteriophage DNA library comprising DNA specifying immunoglobulin genes. The procedures for making a bacteriophage library comprising heterologous DNA are well known in the art and are described, for example, in Sambrook et al. (1989, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, New York).

Bacteriophage which encode the desired antibody, may be engineered such that the protein is displayed on the surface thereof in such a manner that it is available for binding to its corresponding binding protein, e.g., the antigen against which the antibody is directed. Thus, when bacteriophage which express a specific antibody are incubated in the presence of a cell which expresses the corresponding antigen, the bacteriophage will bind to the cell. Bacteriophage which do not express the antibody will not bind to the cell. Such pamiing techniques are well known in the art and are described for example, in Wright et al. (992, Critical Rev. Immunol. 12:125-168). Processes such as those described above, have been developed for the production of human antibodies using M13 bacteriophage display (Burton et al., 1994, Adv. Immunol. 57:191-280). Essentially, a cDNA library is generated from mRNA obtained from a population of antibody-producing cells. The mRNA encodes rearranged immunoglobulin genes and thus, the cDNA encodes the same. Amplified cDNA is cloned into M13 expression vectors creating a library of phage which express human Fab fragments on their surface. Phage which display the antibody of interest are selected by antigen binding and are propagated in bacteria to produce

l-PH/1977697 1 52 soluble human Fab immunoglobulin. Thus, in contrast to conventional monoclonal antibody synthesis, this procedure immortalizes DNA encoding human immunoglobulin rather than cells which express human immunoglobulin.

The procedures just presented describe the generation of phage which encode the Fab portion of an antibody molecule. However, the invention should not be construed to be limited solely to the generation of phage encoding Fab antibodies. Rather, phage which encode single chain antibodies (scFv/phage antibody libraries) are also included in the invention. Fab molecules comprise the entire Ig light chain, that is, they comprise both the variable and constant region of the light chain, but include only the variable region and first constant region domain (CHI) of the heavy chain. Single chain antibody molecules comprise a single chain of protein comprising the Ig Fv fragment. An Ig Fv fragment includes only the variable regions of the heavy and light chains of the antibody, having no constant region contained therein. Phage libraries comprising scFv DNA may be generated following the procedures described in Marks et al. (1991, J. Mol. Biol. 222:581-597). Panning of phage so generated for the isolation of a desired antibody is conducted in a manner similar to that described for phage libraries comprising Fab DNA.

The invention should also be construed to include synthetic phage display libraries in which the heavy and light chain variable regions may be synthesized such that they include nearly all possible specificities (Barbas, 1995, Nature Medicine 1:837-839; de Kruif et al. 1995, J. Mol. Biol. 248:97-105).

Modulators/Inhibitors of FGFRl Expression and/or Function.

The present invention provides modulators of FGFRl expression or function. A molecule that effects an increase or a decrease the biological activity of FGFRl, or that enhances, diminishes, stabilizes, or inhibits FGFRl interaction with an FGFRl ligand, is useful for treating a disease, disorder, or condition of phosphate homeostasis that involves FGFRl. Such a molecule can exert its effects on FGFRl by way of interaction with FGFRl DNA, FGFRl RNA, FGFRl protein, or an FGFRl ligand.

In one embodiment of the present invention, the invention provides a modulator that is an enhancer, stimulator, or agonist which serves to increase the

l-PH/1977697.1 53 availability arid/or^' effective concentration of an FGFRl protein molecule. An agonist useful in this embodiment of the present invention includes a small molecule that increases the activity of FGFRl, a natural or synthetic molecule that increases or enhances at least one of transcription and translation of FGFRl, a small molecule that prevents degradation of FGFRl, a small molecule that enhances or stabilizes the interaction between FGFRl and an FGFRl ligand, and the like. In one embodiment of the present invention, an above-described agonist of FGFRl is useful for treating a phosphate homeostasis disorder including, but not limited to renal insufficiency and tumoral calcinosis. As will be understood by one of skill in the art, such an agonist may serve to decrease phosphate levels in an organism.

In another embodiment of the present invention, the invention provides a modulator that is an enhancer, stimulator, or agonist which serves to increase the availability and/or effective concentration of an FGFRl peptide or protein molecule, wherein such a modulator is a peptide or a protein. In one aspect of the invention, a peptide modulator may be an FGF. In another aspect of the invention, a peptide or protein modulator may be a second molecule of FGFRl . In yet another aspect of the invention, a peptide or protein modulator may be a mutant or a fragment of FGFRl.

In one aspect of the present invention, the invention provides an inhibitor of FGFRl which serves to reduce the availability and/or effective concentration of an FGFRl protein molecule. Such an inhibitor can be an antisense nucleic acid, a ribozyme, or an antibody, as described above. An inhibitor of FGFRl can also be a double stranded RNA molecule that serves to reduce the level of FGFRl mRNA by RNA interference as described (Elbashir et al, 2001, Nature, 411 :428-429; Carthew, 2001, Curr. Opin. Cell Biol., 13:244-248). An inhibitor of FGFRl can also be a large molecule, and can be either a natural or a synthetic molecule. In one embodiment of the present invention, an above-described inbhitor of FGFRl is useful for treating a disorder of phosphate homeostasis including, but not limited to CFDH, ADHR, XLH, and HBD. As will be understood by one of skill in the art, such an inhibitor may serve to increase phosphate levels in a subject. In another embodiment of the present invention, the invention provides an FGFRl inhibitor which serves to decrease the availability and/or effective concentration of an FGFRl protein molecule, wherein such a modulator is a peptide

l-PH/1977697.1 54 or a protein. In ^'brie aspect" of the invention, a peptide or protein modulator may be FGF23. In another aspect of the invention, a peptide or protein modulator may be a second molecule of FGFRl. In yet another aspect of the invention, a peptide or protein modulator may be a mutant or a fragment of FGFRl. In certain situations, it may be desirable to inhibit expression of

FGFRl and the invention therefore includes compositions useful for inhibition of FGFRl expression. Thus, the invention features an isolated nucleic acid complementary to a portion or all of a nucleic acid encoding a mammalian FGFRl which nucleic acid is in an antisense orientation with respect to transcription.

/ Preferably, the antisense nucleic acid is complementary to a nucleic acid having at least about 99.8% homology with SEQ ID NO:l. More preferably, the antisense nucleic acid is complementary with a nucleic acid having at least about 99.9% homology with SEQ ID NO: 1 , or a fragment thereof. Most preferably, the nucleic acid is complementary to a portion or all of a nucleic acid having the sequence of SEQ ID NO: 1 , or a fragment thereof. Such antisense nucleic acid serves to inhibit the expression, function, or both, of a FGFRl .

The invention further provides an inhibitor of FGFRl which serves to inhibit the biological activity of FGFRl, including but not limited to a molecule that blocks the interaction of FGFRl with one or more binding partners or a molecule which inhibits activation of the FGFRl receptor. Specific examples include, but are not limited to, FGF23, other mutant FGFRl receptors, and antibodies, peptides, and peptidomimetics that bind to FGFRl, thereby inhibiting the biological activity of FGFRl. Thus, any type of FGFRl inhibitor is contemplated in the invention, wherein the inhibitor inhibits the expression or biological activity of FGFRl. Based on the sequence of mutant FGFRl disclosed herein, peptidomimetics and other small molecules useful as inhibitors of mutant FGFRl may be generated by the skilled artisan. Specifically, peptidomimetics may be generated using techniques described in PCT/US93/01201.

It is a relatively simple matter, once armed with the present disclosure, to identify a modulator of FGFRl expression or of its biological activity. For example, cells which naturally express FGFRl, or which express FGFRl following transfection with FGFRl encoding nucleic acid may be contacted with a test

l-PH/1977697.1 55 compound. The level of expression of FGFRl in the presence or absence of the test compound is then measured, wherein a higher or lower level of expression of FGFRl in the presence of the test compound compared with the level of FGFRl expression in the absence of the test compound, is an indication that the test compound is a modulator of FGFRl expression. When the level of FGFRl is elevated in the presence of the test compound compared with the level of expression of FGFRl in the absence of the test compound, the test compound is considered to enhance FGFRl expression. Conversely, when the level of FGFRl expression is reduced in the presence of the test compound compared with the level of expression of FGFRl in the absence of the test compound, the test compound is considered to be an inhibitor of FGFRl expression.

FGFRl biological activity can be measured in cells, serum, or urine of a mammal. In this instance, the level of the biological activity of FGFRl produced by cells in the presence or absence of a test compound is measured, wherein a higher or lower level of activity of FGFRl in the presence of the test compound compared with the level of FGFRl activity in the absence of the test compound, is an indication that the test compound is a modulator of FGFRl biological activity. When the level of FGFRl activity is elevated in the presence of the test compound compared with the level of activity of FGFRl in the absence of the test compound, the test compound is considered to enhance FGFRl biological activity. Conversely, when the level of FGFRl activity is reduced in the presence of the test compound compared with the level of activity of FGFRl in the absence of the test compound, the test compound is considered to be an inhibitor of FGFRl biological activity.

Expression of FGFRl may be measured using any ordinary molecular biology technology, such as using RT-PCR technology, RNAse protection, Northern blotting and the like. Alternatively, affects on expression may be measured by operably linking the FGFRl promoter sequence to a suitable reporter gene and transfecting cells with the resulting DNA construct. Promoter activity responsive to the test compound may be measured by measuring the level of the reporter gene expression in cells contacted with the test compound and comparing the level of reporter gene expression in those cells with cells not contacted with the test

l-PH/1977697.1 5 compound. Suitable reporter genes include, but are not limited to beta-galactosidase, chloramphenicol acetyl transferase, green fluorescent protein, and the like.

Using the technology and techniques set forth elsewhere in this application, an FGFRl DNA can be transfected into a cell in order to evaluate the effects of that FGFRl on phosphate metabolism, vitamin D metabolism, and bone metabolism. Cell types useful for such analyses include HEK293 cells, COS cells, and opossum kidney (OK) cells, as well as human bone cell lines MG-63 and Saos-2, and the like.

Methods of Producing FGFRl

The invention provides for a method of producing an isolated polypeptide having the biological activity of FGFRl, as described herein, whereby a host cell comprising a vector encoding FGFRl is cultivated under conditions allowing synthesis of the protein. The protein is subsequently isolated from the cultivated cells and/or cultivated medium. Isolation and purification of the recombinantly produced proteins may be carried out by conventional means including preparative chromatography and affinity and immunological separations involving affinity chromatography with antibodies which bind specifically with FGFRl .

Methods, Kits, and Diagnostic Assays

The invention provides for a method of diagnosing hypophosphatemic and hyperphosphatemic disorders in a subject. In one example provided herein, the data establish that patients with CFDH have a mutation in exon 10 of the human DNA encoding mutant FGFRl, and mutant FGFRl is therefore useful as a diagnostic tool for detection of CFDH. The method exemplified herein comprises contacting a biological sample obtained from the patient with a reagent which detects mutant FGFRl, either a nucleic acid encoding the protein or the protein itself. Detection of mutant FGFRl in the sample, or of the inability to detect mutant FGFRl is diagnostic of mutant FGFRl related hypopohsphatemic and hyperphosphatemic conditions. The biological sample obtained from the subject may be any fluid or tissue in which mutant FGFRl nucleic acid or protein can be detected. Preferably, the sample is white blood cells. However, as known to one of skill in the art, DNA-based

l-PH/1977697.1 57 assays such as those d^'escribed herein can be conducted on any subject sample from which DNA can be obtained. For analysis of RNA expression levels of FGFRl described herein, biological samples include, but are not limited to kidney or small intestine. For analysis of protein expression levels of FGFRl described herein, biological samples include, but are not limited to kidney or small intestine. However, the invention should not be construed to be limited to any particular biological sample obtained from the subject.

Preferred reagents for detection of mutant FGFRl nucleic acid include, but are not limited to, a nucleic acid complementary to the nucleic acid encoding mutant FGFRl. Preferred reagents for detection of mutant FGFRl protein include, but are not limited to, an antibody. It is further preferred that these reagents be labeled to facilitate detection of mutant FGFRl nucleic acid or protein. One skilled in the art would appreciate, based on the disclosure herein, that regents for detection of mutant FGFRl can be labeled using a variety of suitable labels including a radioisotope, a bioluminescent compound, a chemiluminescent compound, a fluorescent compound, a metal chelate, or an enzyme.

In one embodiment of the invention, a mutant FGFRl assay is a competitive assay designed to measure a specific peptide corresponding to a portion of mutant FGFRl as well as mutant FGFRl. The assay is based upon the competition of labeled ¹²⁵I-mutant FGFRl peptide and unlabeled peptide (either standard or an unknown quantity of bodily fluid containing mutant FGFRl) binding to the limited quantity of antibodies specific for the mutant FGFRl peptide in each reaction mixture. As the quantity of standard or unknown in the reaction increases, the amount of ¹²⁵I-mutant FGFRl peptide able to bind to the peptide in decreased. By measuring the amount of ¹²⁵I-mutant FGFRl peptide as a function of the concentration of the unlabeled mutant FGFRl peptide in standard reaction mixtures, a standard curve is constructed from which the concentration of mutant FGFRl in the biological sample can be determined.

The competition assay described above is designed to quantitate the level of mutant FGFRl present in a patient's biological sample. By comparing the presence of mutant FGFRl polypeptide in a given patient's sample to that of a patient known to be unafflicted by a phosphate disorder, the presence of mutant FGFRl can

l-PH/1977697.1 58 be used as an indication that a given patient is afflicted with a hypophosphatemic disorder. This assay may be useful to many hypophosphatemic disorders, including those for which there is no available genetic means of diagnosis. Hypophosphatemic diseases for which this assay may be useful include CFDH, XLH, HHRH, HBD, ADHR, tumor induced osteomalacia, epidermal nevus syndrome, fibrous dysplasia, and nephrolithiasis. For example, as disclosed herein, patients with CFDH will demonstrate the presence of Y372C mutant FGFRl in their DNA.

Also included in the invention is a serum, plasma, or other blood assay for hypophosphatemic conditions as well as assays of urine or other bodily fluids. The assay can be used to diagnose patients having the hypophosphatemic diseases listed above. In one embodiment of the invention, a biological sample obtained from a patient is assessed for the presence of mutant FGFRl as an indication of at least one of the hypophosphatemic diseases listed above. In another embodiment of the invention, a biological sample obtained from a patient is assessed for the level of mutant FGFRl as an indication of at least one of the hypophosphatemic diseases listed above.

The invention provides a method of treating a hypophosphatemic disease in an affected animal, wherein a therapeutically effective amount of a reagent that decreases the expression and/or biological activity of FGFRl is administered to the mammal. Hypophosphatemic diseases which can be treated include, but are not limited to Craniofacial Dysplasia with Hypophosphatemia (CFDH), X-linked hypophosphatemic rickets (XLH), hereditary hypophosphatemic rickets with hypercalciuria (HHRH), hypophosphatemic bone disease (HBD), autosomal dominant hypophosphatemic rickets (ADHR), tumor induced osteomalacia (TIO) or oncogenic hypophosphatemic osteomalacia (OHO), epidermal nevus syndrome, fibrous dysplasia, nephrolithiasis, and the like As disclosed herein, hypophosphatemic disease can be characterized by the presence of mutant FGFRl, which results in an increase in phosphate wasting accompanied by a decrease in serum phosphate levels. Thus, reagents which decrease the expression and/or biological activity of mutant FGFRl will restore normal phosphate homeostasis in hypophosphatemic patients. Examples of reagents which decrease the expression of mutant FGFRl include, but are not limited to, antisense nucleic acids and ribozymes. Examples of reagents that

l-PH/1977697.1 59 decrease the biological activity of mutant FGFRl include, but are not limited to, antibodies and other small molecules that block the interaction between mutant FGFRl and at least one of its binding partners.

In one embodiment of the invention, soluble FGFRl is used to treat a hypophosphatemic disorder. It will be understood by one of skill in the art that a soluble FGFRl or a soluble mutant FGFRl may be administered to a subject in either polynucleotide or polypeptide form. That is, a wild type or mutant soluble FGFRl polynucleotide may be administered to a subject as a transgene therapeutic, the construction and use of which is described elsewhere herein. Alternatively, or in conjunction with the fransgene-based administration of a soluble wild type or mutant FGFRl, a soluble wild type or mutant FGFRl may be administered to a subject in polypeptide form. The administration of therapeutic polypeptides is well-known in the art, and can be achieved using various techniques, including, but not limited to intravenous administration, intramuscular injection, an the like. Pharmaceutical preparations of a soluble FGFRl polypeptide useful in the present aspect of the invention are described elsewhere herein.

One aspect of the present invention provides for treatment of disorders long bone growth in mammals. It has been shown, by way of the present invention, that activation of FGFRl inhibits long bone growth. Y372C mutant FGFRl of the present invention, a hyper-active variant of human FGFRl, results in hypophosphatemic dwarfism in a subject. Thus, a reagent which decreases the expression and/or biological activity of mutant FGFRl will restore normal phosphate homeostasis in a hypophosphatemic patient and will prevent the associated inhibition of long bone growth. Such a reagent will also therefore prevent the dwarfism resulting from the inhibition of long bone growth that is connected with mutant FGFRl -associated hypophosphatemia.

In another aspect of the present invention, a soluble FGFRl and/or a soluble mutant FGFRl (as described elsewhere herein) is used to restore normal phosphate homeostasis in a hypophosphatemic patient and will prevent the associated inhibition of long bone growth and craniosynostosis. By way of the present invention, it has been shown that FGFRl is a binding partner for FGF23. A soluble FGFRl and/or a soluble mutant FGFRl administered to a subject suffering from

l-PH/1977697.1 gQ mutant FGFRl -relaϊed^'hypophosphatemia will serve to bind the FGFs responsible for inhibition of bone elongation and effectively render the bound FGF unavailable to bind with and/or activate mutant membrane-bound (non-soluble) FGFRl. Therefore, a soluble FGFRl and/or a soluble mutant FGFRl may also therefore curtail or prevent the dwarfism resulting from the inhibition of long bone growth that is connected with mutant FGFRl -associated hypophosphatemia.

The invention also provides for a method of treating hyperphosphatemic disease in a mammal, wherein a therapeutically effective amount of an FGFRl -modulating compound is administered to the mammal. Such an FGFRl -modulating compound is an FGFRl agonist, and therefore serves to activate, or enhance the biological activity of FGFRl. Hyperphosphatemic diseases that can be treated include, but are not limited to patients with mild renal insufficiency, tumoral calcinosis and the like. Agonists useful in the present invention include, but are not limited to, a peptide, a protein, a small organic molecule, a large organic molecule, a carbohydrate, a lipid, and the like.

The invention further provides for a method of treating osteoporosis in a mammal, wherein a therapeutically effective amount of a reagent that increases the expression of FGFRl is administered to the mammal. Patients with the hypophosphatemic disease XLH suffer from bone fractures less frequently than patients without the disease (Econs et. al, 1994, Bone and Min., 24: 17-24).

Administration of a reagent that increases the level of FGFRl would produce transient hypophoshatemia with the accompanying effect on bone density and strength. Thus, in addition to its role in regulation of phosphate homeostasis, FGFRl may have an osteoscleretic function in vivo. While not wishing to be bound by theory, the mechanism by which hypophosphatemia leads to increased bone mass likely involves 1,25 dihydroxy vitamin D. Specifically, a reagent that increases the expression of FGFRl may transiently decrease phosphate reabsorption, a reaction which stimulates increased phosphate reabsorption and increased production of 1,25 dihydroxy vitamin D, an effective therapeutic agent for a variety of bone diseases. The present invention includes a method of treating a disorder in a subject, wherein the method includes the administration to a subject afflicted with a disorder of phosphate homeostasis, a disorder of vitamin D metabolism, or a long

l-PH/1977697.1 l bone growth disorder a therapeutically effective amount of a soluble form of FGFRl, thereby alleviating the disorder in the subject. In one embodiment of the invention, the soluble form of FGFRl functions as a competitive antagonist of FGFRl. In another embodiment of the invention, the soluble form of FGFRl functions as a non- competitive antagonist of FGFRl . In yet another embodiment, the soluble form of FGFRl functions as an agonist of FGFRl. In yet another embodiment of the present invention, the soluble FGFRl used to treat a subject is the polypeptide encoded by the wild type FGFRl polynucleotide set forth in SEQ ID NO:4. In still another embodiment of the invention, the soluble FGFRl used to treat a subject is the polypeptide encoded by the Y372C FGFRl polynucleotide set forth in SEQ ID NO: 1. In yet a further embodiment of the invention, the soluble FGFRl used to treat a subject is the polypeptide encoded by the Y374C FGFRl polynucleotide set forth in SEQ ID NO: 16.

The invention further provides a method of treating conditions involving deposition of calcium and phosphate in the arteries or soft tissues of a mammal, wherein a reagent that increases the expression of wild type or mutant FGFRl is administered to the mammal, as described below. Due to increased serum phosphate levels, patients with mild renal insufficiency commonly exhibit deposition of calcium and phosphorous in their coronary arteries, as well as other arteries (including arteries in the exfremities). Deposition of both calcium and phosphate in the arterial wall of the coronary arteries, referred to as coronary artery disease, causes a reduction in blood flow through these arteries and can lead to myocardial infarction. Thus, treatment of coronary artery disease would lessen the risk of developing myocardial infarction. One of skill in the art will recognize that the present invention is also useful for treating other vascular disease arising due to deposition of calcium and phosphate, such as Peripheral Vascular Disease, in addition to disease arising from deposition of calcium and phosphate in arteries, veins, and the like.

Soluble FGFRl (or soluble mutant FGFRl) or a reagent that increases the level of FGFRl serves to reduce the levels of serum phosphate and thereby protect hyperphosphatemic patients from accelerated cardiovascular and coronary artery disease. Nucleic acid encoding FGFRl, or a mutant thereof, is delivered to cells of the coronary artery using methods including, but not limited to, gene therapy. In

l-PH/1977697.1 62 addition, the use of a^'tissue-specifϊc promoter can facilitate selective expression of FGFRl in vascular smooth muscle cells or endothelial cells.

Similarly, a reagent that increases the level of FGFRl is used to treat other conditions involving deposition of calcium and phosphate in soft tissues, including, but not limited to, dermatomyositis and tumoral calcinosis. Tumoral calcinosis is a disorder characterized by increased renal phosphate reabsorption and increased concentrations of 1,25 dihydroxy vitamin D. As a result, patients develop soft tissue calcifications, which are depositions of calcium and phosphate. Increased levels of FGFRl, either native or mutant, in soft tissues using any of the means described herein serves to reverse the biochemical defects. The means of increasing levels of FGFRl in soft tissues include, but are not limited to systemic administration of a reagent, administration directly to the affected tissue, administration to a non- affected tissue, oral administration, and the like, as discussed elsewhere herein.

The invention includes various kits which comprise a compound, such as a nucleic acid encoding FGFRl, an antibody that specifically binds mutant FGFRl, a nucleic acid complementary to a nucleic acid encoding mutant FGFRl but in an antisense orientation with respect to transcription, and/or compositions of the invention, an applicator, and instructional materials which describe use of the compound to perform the methods of the invention. Although exemplary kits are described below, the contents of other useful kits will be apparent to the skilled artisan in light of the present disclosure. Each of these kits is included within the invention.

In one aspect, the invention includes a kit for alleviating a disease mediated by malexpression of FGFRl . The kit is used pursuant to the methods disclosed in the invention. Briefly, the kit may be used to contact a cell with a nucleic acid complementary to a nucleic acid encoding FGFRl where the nucleic acid is in an antisense orientation with respect to transcription to reduce expression of FGFRl, or with an antibody that specifically binds with FGFRl, wherein the decreased expression, amount, or activity of FGFRl mediates an beneficial effect. Moreover, the kit comprises an applicator and an instructional material for the use of the kit. These instructions simply embody the examples provided herein.

l-PH/1977697.1 ζβ The kit optionally includes a pharmaceutically-acceptable carrier. The composition contained within the kit is provided in an appropriate amount as set forth elsewhere herein. Further, the route of administration and the frequency of administration are as previously set forth elsewhere herein. The skilled artisan would appreciate, based upon the disclosure provided herein, that the invention encompasses kits where ribozymes, antisense compositions, antibodies that specifically bind with FGFRl, soluble fragments of FGFRl, and the like, are included, individually or in combination, to reduce the level of FGFRl. Further, the invention comprises a kit comprising a nucleic acid encoding a mammalian mutant FGFRl . Such a kit can be used according to the methods of the invention wherever increased mutant FGFRl is desired. Such conditions include, but are not limited to hyperphosphatemic conditions. Mutant forms of mutant FGFRl as disclosed herein, which are more stable than non-mutant forms, are particularly useful in such kits.

Pharmaceutical Compositions

The invention also encompasses the use pharmaceutical compositions of an appropriate FGFRl modulator to practice the methods of the invention, the compositions comprising an appropriate FGFRl modulator and a pharmaceutically- acceptable carrier.

As used herein, the term "pharmaceutically-acceptable carrier" means a chemical composition with which an appropriate FGFRl modulator may be combined and which, following the combination, can be used to administer the appropriate FGFRl modulator to a mammal.

The pharmaceutical compositions useful for practicing the invention may be administered to deliver a dose of between 1 ng/kg/day and 100 mg/kg/day.

Pharmaceutical compositions that are useful in the methods of the invention may be administered systemically in oral solid formulations, aerosol, topical or other similar formulations. In addition to the appropriate FGFRl modulator, such pharmaceutical compositions may contain pharmaceutically-acceptable carriers and other ingredients known to enhance and facilitate drug administration. Other possible

l-PH/1977697.1 6 formulations, such as nanoparticles, liposomes, resealed erythrocytes, and immunologically based systems may also be used to administer an appropriate FGFRl modulator according to the methods of the invention.

Compounds which are identified using any of the methods described herein may be formulated and administered to a mammal for treatment of the diseases disclosed herein are now described.

The invention encompasses the preparation and use of pharmaceutical compositions comprising a compound useful for treatment of the diseases disclosed herein as an active ingredient. Such a pharmaceutical composition may consist of the active ingredient alone, in a form suitable for administration to a subject, or the pharmaceutical composition may comprise the active ingredient and one or more pharmaceutically acceptable carriers, one or more additional ingredients, or some combination of these. The active ingredient may be present in the pharmaceutical composition in the form of a physiologically acceptable ester or salt, such as in combination with a physiologically acceptable cation or anion, as is well known in the art.

As used herein, the term "pharmaceutically acceptable carrier" means a chemical composition with which the active ingredient may be combined and which, following the combination, can be used to administer the active ingredient to a subject.

As used herein, the term "physiologically acceptable" ester or salt means an ester or salt form of the active ingredient which is compatible with any other ingredients of the pharmaceutical composition, which is not deleterious to the subject to which the composition is to be administered. The formulations of the pharmaceutical compositions described herein may be prepared by any method known or hereafter developed in the art of pharmacology. In general, such preparatory methods include the step of bringing the active ingredient into association with a carrier or one or more other accessory ingredients, and then, if necessary or desirable, shaping or packaging the product into a desired single- or multi-dose unit.

Although the descriptions of pharmaceutical compositions provided herein are principally directed to pharmaceutical compositions which are suitable for

l-PH/1977697.1 65 ethical ad irii^'sfration^'tό^' iuήians, it will be understood by the skilled artisan that such compositions are generally suitable for administration to animals of all sorts. Modification of pharmaceutical compositions suitable for administration to humans in order to render the compositions suitable for administration to various animals is well understood, and the ordinarily skilled veterinary pharmacologist can design and perform such modification with merely ordinary, if any, experimentation. Subjects to which administration of the pharmaceutical compositions of the invention is contemplated include, but are not limited to, humans and other primates, and other mammals. Pharmaceutical compositions that are useful in the methods of the invention may be prepared, packaged, or sold in formulations suitable for oral, parenteral, pulmonary, intranasal, buccal, or another route of administration. Other contemplated formulations include projected nanoparticles, liposomal preparations, resealed erythrocytes containing the active ingredient, and immunologically-based formulations.

A pharmaceutical composition of the invention may be prepared, packaged, or sold in bulk, as a single unit dose, or as a plurality of single unit doses. As used herein, a "unit dose" is discrete amount of the pharmaceutical composition comprising a predetermined amount of the active ingredient. The amount of the active ingredient is generally equal to the dosage of the active ingredient which would be administered to a subject or a convenient fraction of such a dosage such as, for example, one-half or one-third of such a dosage.

The relative amounts of the active ingredient, the pharmaceutically acceptable carrier, and any additional ingredients in a pharmaceutical composition of the invention will vary, depending upon the identity, size, and condition of the subject treated and further depending upon the route by which the composition is to be administered. By way of example, the composition may comprise between 0.1% and 100% (w/w) active ingredient.

In addition to the active ingredient, a pharmaceutical composition of the invention may further comprise one or more additional pharmaceutically active agents. Particularly contemplated additional agents include anti-emetics and scavengers such as cyanide and cyanate scavengers.

l-PH/1977697.1 66

sustained-release formulations of a pharmaceutical composition of the invention may be made using conventional technology.

A formulation of a pharmaceutical composition of the invention suitable for oral administration may be prepared, packaged, or sold in the form of a discrete solid dose unit including, but not limited to, a tablet, a hard or soft capsule, a cachet, a troche, or a lozenge, each containing a predetermined amount of the active ingredient. Other formulations suitable for oral administration include, but are not limited to, a powdered or granular formulation, an aqueous or oily suspension, an aqueous or oily solution, or an emulsion. As used herein, an "oily" liquid is one which comprises a carbon- containing liquid molecule and which exhibits a less polar character than water.

A tablet comprising the active ingredient may, for example, be made by compressing or molding the active ingredient, optionally with one or more additional ingredients. Compressed tablets may be prepared by compressing, in a suitable device, the active ingredient in a free-flowing form such as a powder or granular preparation, optionally mixed with one or more of a binder, a lubricant, an excipient, a surface active agent, and a dispersing agent. Molded tablets may be made by molding, in a suitable device, a mixture of the active ingredient, a pharmaceutically acceptable carrier, and at least sufficient liquid to moisten the mixture. Pharmaceutically acceptable excipients used in the manufacture of tablets include, but are not limited to, inert diluents, granulating and disintegrating agents, binding agents, and lubricating agents. Known dispersing agents include, but are not limited to, potato starch and sodium starch glycollate. Known surface active agents include, but are not limited to, sodium lauryl sulphate. Known diluents include, but are not limited to, calcium carbonate, sodium carbonate, lactose, microcrystalline cellulose, calcium phosphate, calcium hydrogen phosphate, and sodium phosphate. Known granulating and disintegrating agents include, but are not limited to, corn starch and alginic acid. Known binding agents include, but are not limited to, gelatin, acacia, pre-gelatinized maize starch, polyvinylpyrrolidone, and hydroxypropyl methylcellulose. Known lubricating agents include, but are not limited to, magnesium stearate, stearic acid, silica, and talc.

-PH/ 1977697.1 67 Tablets may be non-coated or they may be coated using known methods to achieve delayed disintegration in the gastrointestinal tract of a subject, thereby providing sustained release and absorption of the active ingredient. By way of example, a material such as glyceryl monostearate or glyceryl distearate may be used to coat tablets. Further by way of example, tablets may be coated using methods described in U.S. Patents numbers 4,256,108; 4,160,452; and 4,265,874 to form osmotically-controlled release tablets. Tablets may further comprise a sweetening agent, a flavoring agent, a coloring agent, a preservative, or some combination of these in order to provide pharmaceutically elegant and palatable preparation. Hard capsules comprising the active ingredient may be made using a physiologically degradable composition, such as gelatin. Such hard capsules comprise the active ingredient, and may further comprise additional ingredients including, for example, an inert solid diluent such as calcium carbonate, calcium phosphate, or kaolin. Soft gelatin capsules comprising the active ingredient may be made using a physiologically degradable composition, such as gelatin. Such soft capsules comprise the active ingredient, which may be mixed with water or an oil medium such as peanut oil, liquid paraffin, or olive oil.

Liquid formulations of a pharmaceutical composition of the invention which are suitable for oral administration may be prepared, packaged, and sold either in liquid form or in the form of a dry product intended for reconstitution with water or another suitable vehicle prior to use.

Liquid suspensions may be prepared using conventional methods to achieve suspension of the active ingredient in an aqueous or oily vehicle. Aqueous vehicles include, for example, water and isotonic saline. Oily vehicles include, for example, almond oil, oily esters, ethyl alcohol, vegetable oils such as arachis, olive, sesame, or coconut oil, fractionated vegetable oils, and mineral oils such as liquid paraffin. Liquid suspensions may further comprise one or more additional ingredients including, but not limited to, suspending agents, dispersing or wetting agents, emulsifying agents, demulcents, preservatives, buffers, salts, flavorings, coloring agents, and sweetening agents. Oily suspensions may further comprise a thickening agent. Known suspending agents include, but are not limited to, sorbitol syrup,

l-PH/1977697.1 68 hydrogenate edible fats^'j^" sodium alginate, polyvinylpyrrolidone, gum tragacanth, gum acacia, and cellulose derivatives such as sodium carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose. Known dispersing or wetting agents include, but are not limited to, naturally-occurring phosphatides such as lecithin, condensation products of an alkylene oxide with a fatty acid, with a long chain aliphatic alcohol, with a partial ester derived from a fatty acid and a hexitol, or with a partial ester derived from a fatty acid and a hexitol anhydride (e.g. polyoxyethylene stearate, heptadecaethyleneoxycetanol, polyoxyethylene sorbitol monooleate, and polyoxyethylene sorbitan monooleate, respectively). Known emulsifying agents include, but are not limited to, lecithin and acacia. Known preservatives include, but are not limited to, methyl, ethyl, or n-propyl-para- hydroxybenzoates, ascorbic acid, and sorbic acid. Known sweetening agents include, for example, glycerol, propylene glycol, sorbitol, sucrose, and saccharin. Known thickening agents for oily suspensions include, for example, beeswax, hard paraffin, and cetyl alcohol. Liquid solutions of the active ingredient in aqueous or oily solvents may be prepared in substantially the same manner as liquid suspensions, the primary difference being that the active ingredient is dissolved, rather than suspended in the solvent. Liquid solutions of the pharmaceutical composition of the invention may comprise each of the components described with regard to liquid suspensions, it being understood that suspending agents will not necessarily aid dissolution of the active ingredient in the solvent. Aqueous solvents include, for example, water and isotonic saline. Oily solvents include, for example, almond oil, oily esters, ethyl alcohol, vegetable oils such as arachis, olive, sesame, or coconut oil, fractionated vegetable oils, and mineral oils such as liquid paraffin. Powdered and granular formulations of a pharmaceutical preparation of the invention may be prepared using known methods. Such formulations may be administered directly to a subject, used, for example, to form tablets, to fill capsules, or to prepare an aqueous or oily suspension or solution by addition of an aqueous or oily vehicle thereto. Each of these formulations may further comprise one or more of dispersing or wetting agent, a suspending agent, and a preservative. Additional excipients, such as fillers and sweetening, flavoring, or coloring agents, may also be included in these formulations.

l-PH/1977697.1 69 A pharmaceutical composition of the invention may also be prepared, packaged, or sold in the form of oil-in- water emulsion or a water-in-oil emulsion. The oily phase may be a vegetable oil such as olive or arachis oil, a mineral oil such as liquid paraffin, or a combination of these. Such compositions may further comprise one or more emulsifying agents such as naturally occurring gums such as gum acacia or gum tragacanth, naturally-occurring phosphatides such as soybean or lecithin phosphatide, esters or partial esters derived from combinations of fatty acids and hexitol anhydrides such as sorbitan monooleate, and condensation products of such partial esters with ethylene oxide such as polyoxyethylene sorbitan monooleate. These emulsions may also contain additional ingredients including, for example, sweetening or flavoring agents.

As used herein, "parenteral administration" of a pharmaceutical composition includes any route of administration characterized by physical breaching of a tissue of a subject and administration of the pharmaceutical composition through the breach in the tissue. Parenteral administration thus includes, but is not limited to, administration of a pharmaceutical composition by injection of the composition, by application of the composition through a surgical incision, by application of the composition through a tissue-penetrating non-surgical wound, and the like. In particular, parenteral administration is contemplated to include, but is not limited to, subcutaneous, intraperitoneal, intramuscular, intrasternal injection, and kidney dialytic infusion techniques.

Formulations of a pharmaceutical composition suitable for parenteral administration comprise the active ingredient combined with a pharmaceutically acceptable carrier, such as sterile water or sterile isotonic saline. Such formulations may be prepared, packaged, or sold in a form suitable for bolus administration or for continuous administration. Injectable formulations may be prepared, packaged, or sold in unit dosage form, such as in ampules or in multi-dose containers containing a preservative. Formulations for parenteral administration include, but are not limited to, suspensions, solutions, emulsions in oily or aqueous vehicles, pastes, and implantable sustained-release or biodegradable formulations. Such formulations may further comprise one or more additional ingredients including, but not limited to, suspending, stabilizing, or dispersing agents. In one embodiment of a formulation for

l-PH/1977697.1 7Q parenteral administration, the active ingredient is provided in dry (i.e. powder or granular) form for reconstitution with a suitable vehicle (e.g. sterile pyrogen-free water) prior to parenteral administration of the reconstituted composition.

The pharmaceutical compositions may be prepared, packaged, or sold in the form of a sterile injectable aqueous or oily suspension or solution. This suspension or solution may be formulated according to the known art, and may comprise, in addition to the active ingredient, additional ingredients such as the dispersing agents, wetting agents, or suspending agents described herein. Such sterile injectable formulations may be prepared using a non-toxic parenterally-acceptable diluent or solvent, such as water or 1,3 -butane diol, for example. Other acceptable diluents and solvents include, but are not limited to, Ringer's solution, isotonic sodium chloride solution, and fixed oils such as synthetic mono- or di-glycerides. Other parentally-administrable formulations which are useful include those which comprise the active ingredient in microcrystalline form, in a liposomal preparation, or as a component of a biodegradable polymer systems. Compositions for sustained release or implantation may comprise pharmaceutically acceptable polymeric or hydrophobic materials such as an emulsion, an ion exchange resin, a sparingly soluble polymer, or a sparingly soluble salt.

A pharmaceutical composition of the invention may be prepared, packaged, or sold in a formulation suitable for pulmonary administration via the buccal cavity. Such a formulation may comprise dry particles which comprise the active ingredient and which have a diameter in the range from about 0.5 to about 7 nanometers, and preferably from about 1 to about 6 nanometers. Such compositions are conveniently in the form of dry powders for administration using a device comprising a dry powder reservoir to which a stream of propellant may be directed to disperse the powder or using a self-propelling solvent/powder-dispensing container such as a device comprising the active ingredient dissolved or suspended in a low- boiling propellant in a sealed container. Preferably, such powders comprise particles wherein at least 98% of the particles by weight have a diameter greater than 0.5 nanometers and at least 95% of the particles by number have a diameter less than 7 nanometers. More preferably, at least 95% of the particles by weight have a diameter greater than 1 nanometer and at least 90% of the particles by number have a diameter

l-PH/1977697.1 η\ ^{,f ■}leSs"tharι"6 o ne'tefs;' Dry powder compositions preferably include a solid fine powder diluent such as sugar and are conveniently provided in a unit dose form.

Low boiling propellants generally include liquid propellants having a boiling point of below 65 degrees F at atmospheric pressure. Generally the propellant may constitute 50 to 99.9% (w/w) of the composition, and the active ingredient may constitute 0.1 to 20% (w/w) of the composition. The propellant may further comprise additional ingredients such as a liquid non-ionic or solid anionic surfactant or a solid diluent (preferably having a particle size of the same order as particles comprising the active ingredient). Pharmaceutical compositions of the invention formulated for pulmonary delivery may also provide the active ingredient in the form of droplets of a solution or suspension. Such formulations may be prepared, packaged, or sold as aqueous or dilute alcoholic solutions or suspensions, optionally sterile, comprising the active ingredient, and may conveniently be administered using any nebulization or atomization device. Such formulations may further comprise one or more additional ingredients including, but not limited to, a flavoring agent such as saccharin sodium, a volatile oil, a buffering agent, a surface active agent, or a preservative such as methylhydroxybenzoate. The droplets provided by this route of administration preferably have an average diameter in the range from about 0.1 to about 200 nanometers.

The formulations described herein as being useful for pulmonary delivery are also useful for intranasal delivery of a pharmaceutical composition of the invention.

Another formulation suitable for intranasal administration is a coarse powder comprising the active ingredient and having an average particle from about 0.2 to 500 micrometers. Such a formulation is administered in the manner in which snuff is taken i.e. by rapid inhalation through the nasal passage from a container of the powder held close to the nares.

Formulations suitable for nasal administration may, for example, comprise from about as little as 0.1% (w/w) and as much as 100% (w/w) of the active ingredient, and may further comprise one or more of the additional ingredients described herein.

l-PH/1977697.1 72 !,.;^;■ ;:.:.f! ii ^'•'^•it ..^•' u ■< 'Α-pKa aceutical composition of the invention may be prepared, packaged, or sold in a formulation suitable for buccal administration. Such formulations may, for example, be in the form of tablets or lozenges made using conventional methods, and may, for example, 0.1 to 20% (w/w) active ingredient, the balance comprising an orally dissolvable or degradable composition and, optionally, one or more of the additional ingredients described herein. Alternately, formulations suitable for buccal administration may comprise a powder or an aerosolized or atomized solution or suspension comprising the active ingredient. Such powdered, aerosolized, or aerosolized formulations, when dispersed, preferably have an average particle or droplet size in the range from about 0.1 to about 200 nanometers, and may further comprise one or more of the additional ingredients described herein.

As used herein, "additional ingredients" include, but are not limited to, one or more of the following: excipients; surface active agents; dispersing agents; inert diluents; granulating and disintegrating agents; binding agents; lubricating agents; sweetening agents; flavoring agents; coloring agents; preservatives; physiologically degradable compositions such as gelatin; aqueous vehicles and solvents; oily vehicles and solvents; suspending agents; dispersing or wetting agents; emulsifying agents, demulcents; buffers; salts; thickening agents; fillers; emulsifying agents; antioxidants; antibiotics; antifungal agents; stabilizing agents; and phaimaceutically acceptable polymeric or hydrophobic materials. Other "additional ingredients" which may be included in the pharmaceutical compositions of the invention are known in the art and described, for example in Genaro, ed., 1985, Remington's Pharmaceutical Sciences, Mack Publishing Co., Easton, PA, which is incorporated herein by reference. Typically dosages of the compound of the invention which may be administered to an animal, preferably a human, range in amount from 1 microgram to about 100 grams per kilogram of body weight of the animal. While the precise dosage administered will vary depending upon any number of factors, including but not limited to, the type of animal and type of disease state being treated, the age of the animal and the route of administration. Preferably, the dosage of the compound will vary from about 1 mg to about 10 g per kilogram of body weight of the animal. More

l-PH/1977697.1 73

vary from about 10 mg to about 1 g per kilogram of body weight of the animal.

The compound may be administered to an animal as frequently as several times daily, or it may be administered less frequently, such as once a day, once a week, once every two weeks, once a month, or even lees frequently, such as once every several months or even once a year or less. The frequency of the dose will be readily apparent to the skilled artisan and will depend upon any number of factors, such as, but not limited to, the type and severity of the disease being treated, the type and age of the animal, etc.

EXPERIMENTAL EXAMPLES

The invention is further described in detail by reference to the following experimental examples. These examples are provided for purposes of illustration only, and are not intended to be limiting unless otherwise specified. Thus, the invention should in no way be construed as being limited to the following examples, but rather, should be construed to encompass any and all variations which become evident as a result of the teaching provided herein.

Example 1: Clinical evaluation of CFDH patients

The Indiana University Institutional Review Board has approved the research protocol and all subjects gave written informed consent prior to participating in the studies.

Upon clinical evaluation at the age of 26, the proband had marked growth retardation, with a peak stature of 41 inches, and a weight of 100 pounds. He possessed a distinct facial phenotype, including high arched palate with no cleft palate, severe nasal maxillary hypoplasia, hypertelorism, and orbital deformities. In addition, the patient never had tooth eruption, as documented upon X-ray analysis, and used dentures all of his life. The disorder also manifested with shortened limbs, shortened neck, broad thumbs, and bradydactyly. The proband had multiple surgeries, totaling 52, including the LeFortlll procedure on three occasions for advancement of the middle third of his face, operations to reconstruct the forehead, vertex cranioplasty, as well as correction of the bony hypercathorum. The proband' s ribs were used to construct the bridge of his nose.

l-PH/1977697.1 74 ^,| ;^{i ,!} .^, !ⁱ ϊ, H- ^{■ ' ii !i} ] __ra^ aήέlysis of the proband revealed that the patient had a fracture of the fourth left rib, as well as possible fracture of the right humerus. The proband had severe osteomalacia and generalized osteopenia that was confirmed upon DEXA analysis of the lumbar spine: 0.47 g/cm (-5.7 S.D. below the mean) and right hip: 0.08 g/cm² (-7.9 S.D.). A patient history revealed that between the ages of 6 and 7 years, he had tibial osteotemies for correction of lower extremity bowing. The proband was active most of his life, but his physical activity declined over his lifespan because of severe pain in the knees, hips, and back, and he developed pathologic fractures involving the proximal humerus bilaterally. Biochemical analyses of CFDH patients

Laboratory values for the proband at age 26, and his father at age 55, as well as the standard ranges, are shown in Table 1. Evaluation indicated that the proband had a low serum phosphorus of 1.0 mg/dl, whereas total serum calcium was normal at 9.2 mg/dl. Intact parathyroid was normal, and thyroid function tests, including a TSH and free T4 were also within the normal range. Alkaline phosphatase was markedly elevated at 297 U/L. However, total serum protein and albumin were normal. In addition, 25-hydroxy vitamin D was within the normal range, 36 ng/ml (normal 15-57 ng/ml), in contrast his l,25(OH) vitamin D₃ was inappropriately suppressed at 10 pg/ml, considering the degree of hypophosphatemia, and after repeating the measurement, was undetectable. Nephrogenous cAMP measurements were obtained on two occasions and found to be within the normal range at 1.0 and 1.3 nmoles/lOOml GFR (normal range 0-2.8 nmoles/lOOml GFR). In addition, the patient's TMP/GFR were also obtained on two different occasions and were both found to be markedly low at 0.9 mg/dl (normal range 2.5-4.5 mg/dl), indicating severe renal phosphate wasting. The patient had never been treated with phosphorus or vitamin D, and a urine screen for mucupolysaccharidosis was negative. The proband' s father had the same syndrome, being affected with dwarfism, severe cranial deformities, and hypophosphatemia with extreme phosphate wasting (Table 2). The proband's brother was also growth restricted and had craniofacial dysmorphism, however his biochemical status was unknown.

-PH/1977697 1 75

Table 1. Biochemical evaluation of proband and proband's father. Laboratory values are shown for the proband at age 26 and his father at age 55.

A follow up analysis on affected family members was not performed because the proband died at the age of 28, due to a pulmonary embolism as a consequence of extended immobilization due to bone pain and fracture. The proband's father died at the age of 59 due to respiratory distress, under similar immobilizing conditions; and the patient's brother died at the age of 24 of pneumonia and respiratory complications. The proband's biological mother is unaffected, as were his maternal grandparents. A paternal grandfather, paternal uncle and paternal aunt were also reported to be unaffected. The proband's father had a normal karyotyp, and the dwarfism and phosphate wasting phenotypes co-segregate in the affected individuals. The mutation was therefore inherited in an autosomal dominant fashion and this novel disorder is referred to elsewhere herein as CFDH.

Example 2: Identification, creation and analysis of FGFRl mutations Cloning protocol

Primers were designed to flank the known FGFR exons (FGFRl : GenBank Accession no. NT_008045; FGFR2: AF097336-AF097354; FGFR3: (Wuchner et al, 1997, Human Genetics 100:215-219), with modifications to obtain 3' coding region of exon 6 and the splice junction nucleotides; FGFR4: NT_023132; FGFR5: NT_006111) using the Primer3 program («www- genome.wi.mit.edu/cgi-bin/primer/primer3_www.cgi»). Genomic DNA was PCR amplified using the intronic primers (sequences available upon request) according to standard protocols, the products purified with the Qiaquick Kit

l-PH/1977697.1 76 ' (^'QlAgen,Tn6.)'^ t eii analyzed by direct DNA sequencing. Sequencing was performed using the Thermosequenase Kit (Amersham; Cleveland, OH) with (α-

33p) ddNTP (Amersham, Cleveland, OH) incorporation. Sequencing reactions were resolved on a standard 0.2 mm, 6% polyacrylamide gel and autoradiography was performed.

Using RFLP analysis, FGFRl exon 10 was amplified from patient and control DNA using primers flanking FGFRl exon 10: forward 5'- ACTGACTCAGCCCTGGAAGA-3' (SEQ ID NO:6), reverse 5'- CGCAGAGGGATGTTG-3' (SEQ ID NO:7). Resulting products were digested with 30 units of Rsal (New England Biolabs, Beverly, MA) then electrophoresed on 2% ethidium bromide stained agarose gels to resolve restriction fragments. The mutation in FGFRl was sequenced using the Thermosequenase Kit (Amersham; Cleveland, OH) with (α-33p) ddNTP (Amersham, Cleveland, OH). Forward and reverse primers specific for the Y372C mutation are set forth in SEQ ID NO:8 and SEQ ID NO:9, resepectively.

Mutational analyses

To test whether mutations in an FGFR caused CFDH, primers were designed to span the coding region and intron-exon splice junctions of the 18 FGFRl coding exons. Direct sequencing of DNA samples from the proband and his father revealed a heterozygous A/G missense mutation at nucleotide 1115 within exon 10, resulting in a cysteine substitution for the tyrosine at amino acid position 372 (Y372C) (Figure 2). Control individuals, as well as the proband's biological mother were negative for the mutation and all other FGFRl exons were negative for nucleotide substitutions. The Al 115G change created a novel Rsal restriction site, and RFLP mapping of exon 10 revealed that the mutation was not found in genomic DNA from 880 control alleles. The mutated Y372 residue is predicted to lie within the juxta extramembrane region of FGFRl, and is conserved between human FGFRl -3, as well as mouse FGFRl (Figure 1) Mutations in the corresponding tyrosine residue (Y375C) in FGFR2 causes Beare-Stevenson cutis gyrata syndrome, characterized by furrowed skin (cutis gyrata), acanthosis nigricans, craniosynostosis, craniofacial

l-PH/1977697 1 77 , , . „ ,_f - . , ysmorphisih, digital^' anomalies, umbilical and anogenital abnormalities, and early death. In addition, a Y373C change in FGFR3 causes thanatophoric dwarfism type I

(Figure 1), characterized by craniosynostosis, very short ribs and bones of the extremities, with vertebral bodies greatly reduced in height, wide intervertebral spaces, and is also associated with neonatal lethality.

Additional mutational analyses performed on the coding exons comprising FGF23, FGFR2, FGFR3, FGFR4, and FGFR5 using DNA samples from the CFDH kindred as well as samples from index cases of tumoral calcinosis, hypophosphatemic bone disease (HBD) (Scriver et al., 1977, American Journal of Medical Genetics 1:101-117), and two adult-onset hypophosphatemia cases with unknown etiologies, detected only silent polymorphisms or nucleotide changes that were also present in control DNA samples.

Study of Phosphate Transport in Y372C FGFRl Transgenic Mice To evaluate phosphaturia in CFDH, wild type FGFRl , Y372C FGFRl , and vector control are transfected into OK cells and phosphate transport is monitored. The effects of 100, 10, and 1 ng/ml FGF23 treatment (with and without heparin added) in OK cells transfected with either wild type, mutant FGFRl or vector control is conducted in conjunction with the phosphate transport analysis in order to monitor the role of FGFRl in phosphate transport. Further, the effect of FGF23 on the Y372C FGFRl receptor is illustrated by the aforementioned procedure.

OK cells are transfected with the above-mentioned FGFR constructs in 100 mm dishes for 24 h, then the dishes are trypsinized and the cells combined. Cells are counted, then the transfected cells are plated at a density of lxl 0⁵ cells/well in 24 well plates to assure equal numbers of transfected cells per well. An aliquot of pooled cells is held in reserve to confirm transfection by Western analysis with anti-FGFRl antibodies. Transfection efficiency is assessed by comparison to cells transfected in parallel with a β-galactosidase reporter construct. Cells are incubated for 0, 4 or 24 h with or without FGF23. Cells are then washed using a choline-containing wash solution at 37°C, then uptake is initiated by switching to 0.2ml of uptake solution containing either choline or Na with P orthophosphate for 5 min. Reactions are stopped with four washes of one ml cold choline stop solution, and 0.4 ml of 0.2N

l-PH/1977697.1 78 NaOΗ'ϊs a'dded'Tor^"z^!"h for cell lysis. Two x 80 μl aliquots from each well are assayed for incorporated radioactivity via scintillation counting. Protein concentrations are assessed on the remaining cellular lysates. Time zero and total counts are ascertained and the transport results are assessed as nanomoles of ³²P/ mg protein/5 min. To control for nonspecific effects on phosphate transport, transport of glucose and alanine are also assessed using established protocols, as known to one of skill in the art (Tenenhouse and Mattel, 1993, American Journal of Physiology 265(1 Pt 1):C54- 61).

Discussion

FGF receptors are critical for bone formation and function, and it is clear that the FGFRs and FGFs have physiological roles in addition to their known control of development and differentiation. It was recently demonstrated that missense mutations in FGF23 are responsible for the renal phosphate wasting disorder autosomal dominant hypophosphatemic rickets (ADHR) (White et al., 2000, Nature Genetics 26:345-348). Based upon the fact that a mutation in an FGF causes a disorder of phosphate homeostasis, novel mutations in the FGFRs could also lead to disorders of perturbed renal phosphate homeostasis, which would, in turn, implicate the mutated receptor as the receptor for FGF-23. The Y372C FGFRl mutant receptor reported herein is significant in several regards. From the standpoint of mineral ion homeostasis, the idea that an FGFR plays a role in renal phosphate homeostasis is unique, and from a skeletal biology aspect, the Y372C change in FGFRl directly demonstrates that an FGFR besides FGFR3 acts as a negative regulator of long bone elongation. Mutations in the FGFRs are known to cause heritable disorders of skeletal formation. A unique Y372C mutation in FGFRl was detected in the CFDH family that was not found in a significant number of control subjects (Figure 2). The most common mutation reported in FGFRl to date is the Pro252Arg (P252R) mutation that results in Pfeiffer (Muenlce et al., 1994, Nature Genetics 8:269-274) or Jackson- Weiss syndromes (Roscioli et al, 2000, Am. J. Med. Genet. 93(l):22-8), characterized by broad toes as well as craniosynostosis. The P252R change is localized between the second and third Ig-like domains (Muenke et al., 1994, Nature

l-PH/1977697.1 79 ^'Genetics 8:2δ9-2?4^')^'!;^''well upstream from the Y372C mutation described within this report (Figure 2). The only other reported FGFRl mutation was a single case with a heterozygous Ile300Thr change in Ig-like domain III, causative for non-syndromic trigonocephaly. This disorder is characterized by a keel-shaped deformation of the forehead caused by premature closing of the frontal suture. The patient had a misshapen head, as well as two skin appendices, one on the right cheek and one on the right ear. She also displayed hypotelorism, had a short nose with broad nasal bridge, and a high arched and narrow palate. Her limbs had a normal shape, with no dysmorphisms except for slightly broadened big toes. The comparisons of the described mutations within FGFRl reinforce the idea that the precise localization of the mutations within any of the FGFRs is critical in determining the resulting phenotype. Indeed, mutations in the FGFRl extracellular binding domains described above that result in Pfieffer syndrome and non-syndromic trigonocephaly result in disorders that do not possess the severe phosphate-wasting phenotype observed in CFDH (Table 1).

The Y375C FGFR2 and Y373C FGFR3 mutations that are complimentary to the FGFRl Y372C change that cause Beare-Stevenson cutis gyrata syndrome and thanatophoric dwarfism type I have not been reported to lead to a phosphate wasting phenotype. Lower extremity bowing, a sign of long-term hypophosphatemia, has been reported in thanatophoric dwarfism type I, however the deformities occur at birth, so the bone phenotype is most likely not due to an effect of hypophosphatemia, but rather to a bone formation defect due to activation of FGFRS. The Beare-Stevenson cutis gyrata syndrome and thanatophoric dwarfism type I are extremely severe and lead to neonatal death, whereas the patients in this study lived well into adulthood. This observation reinforces the idea that not only is the precise location of an FGFR mutation critical, but that the receptor itself that carries the mutation is a key factor in producing the resulting disease phenotype.

The disclosures of each and every patent, patent application, and publication cited herein are hereby incorporated herein by reference in their entirety.

l-PH/1977697.1 80 "^'"" 'Wn^'ife^'ffis invention has been disclosed with reference to specific embodiments, it is apparent that other embodiments and variations of this invention may be devised by others skilled in the art without departing from the true spirit and scope of the invention. The appended claims are intended to be construed to include all such embodiments and equivalent variations.

l-PH/1977697.1 81

Claims

CLAIMS What is claimed is:

1. A method of treating a phosphate homeostasis disorder in a mammal, said method comprising administering to a mammal afflicted with said disorder a therapeutically effective amount of an FGFRl agonist, thereby alleviating said phosphate homeostasis disorder in said mammal.

2. The method of claim 1, wherein said phosphate homeostasis disorder is selected from the group consisting of craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia.

3. The method of claim 1, wherein said mammal is a human.

4. The method of claim 1, wherein said agonist enhances FGFRl - FGF23 binding.

5. The method of claim 1, wherein said agonist binds to FGFRl.

6. The method of claim 1, wherein said agonist binds to FGF23.

7. The method of claim 1, wherein a molecule of said agonist binds to both FGFRl and FGF23.

8. The method of claim 1, wherein said agonist has the properties of binding to FGFRl and FGF23.

l-PH/1977697.1 82

9. ϊhe method of claim 1, wherein said agonist is selected from the group consisting of peptide, protein, compound, small organic molecule, large organic molecule, carbohydrate, and lipid.

10. A method of treating a hypophosphatemic disorder in a mammal, said method comprising administering to a mammal afflicted with said disorder a therapeutically effective amount of a soluble form of FGFRl, whereby the soluble form of FGFRl functions as a competitive antagonist of FGFRl, thereby alleviating said disorder in said mammal.

11. A method of treating a hypophosphatemic disorder in a mammal, said method comprising administering to a mammal afflicted with said disorder a therapeutically effective amount of a soluble form of Y372C mutant FGFRl, whereby the soluble form of Y372C mutant FGFRl functions as a competitive antagonist of cellular FGFRl, thereby alleviating said disorder in said mammal.

12. A method of treating a hypophosphatemic disorder in a mammal, said method comprising administering to a mammal afflicted with said disorder a therapeutically effective amount of a soluble form of a mutant FGFRl polypeptide encoded by a polynucleotide comprising the polynucleotide set forth in SEQ ID NO: 1, whereby the soluble form of the mutant FGFRl polypeptide functions as a competitive antagonist of cellular FGFRl, thereby alleviating said disorder in said mammal.

13. A method of treating a hypophosphatemic disorder in a mammal, said method comprising administering to a mammal afflicted with said disorder a therapeutically effective amount of a soluble fragment of FGFRl, whereby the soluble fragment of FGFRl functions as a competitive antagonist of cellular FGFRl, thereby alleviating said disorder in said mammal.

l-PH/1977697.1 83 "14. "K method of treating a hypophosphatemic disorder in a mammal, said method comprising administering to a mammal afflicted with said disorder a therapeutically effective amount of a soluble fragment of FGFRl, whereby the soluble fragment of FGFRl functions as a competitive antagonist of cellular FGFRl by inhibiting FGFRl -FGF23 interaction, thereby alleviating said disorder in said mammal.

15. The method of claim 10, wherein said phosphate homeostasis disorder is selected from the group consisting of craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia.

16. The method of claim 10, wherein said mammal is a human.

17. A method of treating a phosphate homeostasis disorder in a mammal, said method comprising administering to a mammal afflicted with said disorder a therapeutically effective amount of an FGFRl antagonist, thereby alleviating said phosphate homeostasis disorder in said mammal.

18. The method of claim 17, wherein said phosphate homeostasis disorder is chosen from the group consisting of hyperphosphatemic disorders and hypophosphatemic disorders.

19. The method of claim 17, wherein the phosphate homeostasis disorder is chosen from the group consisting of craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia.

20. A method of treating a phosphate homeostasis disorder in a mammal, said method comprising administering to a mammal afflicted with said

l-PH/1977697.1 84 ^' disorder^' a^'therapeutically effective amount of an FGFRl antagonist, thereby alleviating said phosphate homeostasis disorder in said mammal.

21. The method of claim 17, wherein said FGFRl antagonist is a competitive antagonist.

22. The method of claim 17, wherein said FGFRl antagonist is selected from the group consisting of wild type FGFRl, a mutant FGFRl, and an FGFRl fragment.

23. The method of claim 17, wherein said FGFRl antagonist inhibits FGFRl -FGF23 binding.

24. The method of claim 17, wherein said mammal is a human.

25. The method of claim 17, wherein said FGFRl antagonist enhances FGFRl -FGF23 binding.

26. The method of claim 17, wherein said antagonist binds to FGFRL

27. The method of claim 17, wherein said antagonist binds to FGF23.

28. The method of claim 17, wherein a molecule of said antagonist simultaneously binds to FGFRl and FGF23.

29. The method of claim 17, wherein said antagonist has the properties of binding to FGFRl and FGF23.

30. The method of claim 17, wherein said agonist is selected from the group consisting of peptide, protein, compound, small organic molecule, large organic molecule, carbohydrate, and lipid.

l-PH/1977697.1 85

31. A method of diagnosing a phosphate homeostasis disorder in a mammal, said method comprising contacting a mammalian biological sample with a reagent that detects the presence or absence of a mutation in a nucleic acid encoding FGFRl, wherein said mutation encodes a Y372C FGFRl mutant protein as set forth in SEQ ID NO:2, assessing the presence or absence of said mutation in said sample, wherein the presence of said mutation is an indication that said mammal is afflicted with said disorder, thereby diagnosing said phosphate homeostasis disorder in said mammal.

32. The method of claim 31 , wherein said phosphate homeostasis disorder is selected from the group consisting of craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia.

33. The method of claim 31 , wherein the nucleic acid encoding a

Y372C FGFRl protein comprises a Al 115->G1115 mutation.

34. The method of claim 31 , wherein the nucleic acid encoding a Y372C FGFRl protein comprises a Al 115-^Gl 115 mutation and a Cl 116-^Tl 116 mutation.

35. The method of claim 31, wherein said reagent is a nucleic acid.

36. The method of claim 31, wherein said reagent is detectably labeled.

37. The method of claim 31, wherein said reagent is detectably labeled with a label selected from the group consisting of a radioisotope, a bioluminescent compound, a chemiluminescent compound, a fluorescent compound, a metal chelate, and an enzyme.

l-PH/1977697.1 86 3^'B.^''^"'A'^"method of diagnosing a phosphate homeostasis disorder in a mammal, said method comprising contacting a mammalian biological sample with a reagent that detects the presence or absence of a Y372C mutation in an FGFRl polypeptide, assessing the presence or absence of said mutation in said sample, wherein the presence of said mutation is an indication that said mammal is afflicted with said disorder, thereby diagnosing said phosphate homeostasis disorder in said ι mammal.

39. The method of claim 38, wherein said phosphate homeostasis disorder is selected from the group consisting of craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia.

40. The method of claim 38, wherein said reagent is an FGFRl antibody.

41. The method of claim 38, wherein said reagent is detectably labeled.

42. The method of claim 38, wherein said reagent is detectably labeled with a label selected from the group consisting of a radioisotope, a bioluminescent compound, a chemiluminescent compound, a fluorescent compound, a metal chelate, and an enzyme.

43. A kit for diagnosing a phosphate homeostasis disorder in a mammal, said kit comprising a reagent which detects the presence or absence of a mutation in a nucleic acid sequence encoding FGFRl, wherein the mutation encodes for a Y372C FGFRl mutant protein as set forth in SEQ ID NO:2 and further wherein the presence of said mutation is an indication that said mammal is afflicted with said disorder, said kit further comprising an applicator, and an instructional material for the use thereof.

l-PH/1977697.1 87

44. The kit of claim 43, wherein the phosphate homeostasis disorder is chosen from the group consisting of a hyperphosphatemic disorder and a hypophosphatemic disorder.

45. The kit of claim 43, wherein the phosphate homeostasis disorder is chosen from the group consisting of craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia.

46. The kit of claim 43, wherein the nucleic acid encoding a Y372C FGFRl protein comprises a A1115->G1115 mutation.

47. The kit of claim 43, wherein said reagent is a nucleic acid.

48. The kit of claim 43, wherein said reagent is detectably labeled.

49. The kit of claim 43, wherein said reagent is detectably labeled with a label selected from the group consisting of a radioisotope, a bioluminescent compound, a chemiluminescent compound, a fluorescent compound, a metal chelate, and an enzyme.

50. A kit for diagnosing a phosphate homeostasis disorder in a mammal, said kit comprising a reagent which detects the presence or absence of a Y372C mutation in an FGFRl polypeptide, wherein the presence of said mutation is an indication that said mammal is afflicted with said disorder, said kit further comprising an applicator, and an instructional material for the use thereof.

51. The kit of claim 50, wherein said phosphate homeostasis disorder is selected from the group consisting of craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked

l-PH/1977697.1 88 hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia.

52. The kit of claim 50, wherein said reagent is an FGFRl antibody.

53. The kit of claim 50, wherein said reagent is detectably labeled.

54. The kit of claim 50, wherein said reagent is detectably labeled with a label selected from the group consisting of a radioisotope, a bioluminescent compound, a chemiluminescent compound, a fluorescent compound, a metal chelate, and an enzyme.

55. A kit for diagnosing a phosphate homeostasis disorder in a mammal, said kit comprising a reagent which detects the level of a FGFRl polypeptide in a sample, wherein an increase or decrease in the level of FGFRl polypeptide compared with the level of FGFRl in a mammal not afflicted with a phosphate homeostasis disorder is an indication that said mammal is afflicted with said disorder, said kit further comprising an applicator, and an instructional material for the use thereof.

56. The kit of claim 55, wherein said phosphate homeostasis disorder is selected from the group consisting of craniofacial dysplasia with hypophosphatemia, renal insufficiency, tumoral calcinosis, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, tumor induced osteomalacia, epidermal nevus syndrome, and fibrous dysplasia.

57. The kit of claim 55, wherein said reagent is an FGFRl antibody.

58. The kit of claim 55, wherein said reagent is detectably labeled.

59. The kit of claim 55, wherein said reagent is detectably labeled with a label selected from the group consisting of a radioisotope, a bioluminescent

l-PH/1977697.1 89 compound, a chemiluminescent compound, a fluorescent compound, a metal chelate, and an enzyme.

60. An isolated nucleic acid comprising the nucleic acid set forth in SEQ ID NO: 1.

61. An isolated nucleic acid comprising a nucleic acid encoding the polypeptide set forth in SEQ ID NO:2.

62. The isolated nucleic acid of claim 60, said isolated nucleic acid further comprising a nucleic acid encoding a tag polypeptide covalently linked thereto.

63. The isolated nucleic acid of claim 62, wherein said tag polypeptide is selected from the group consisting of a myc tag polypeptide, a glutathione-S- transferase tag polypeptide, a green fluorescent protein tag polypeptide, a myc- pyruvate kinase tag polypeptide, a His6 tag polypeptide, an influenza vims hemagglutinin tag polypeptide, a flag tag polypeptide, a V5 tag, and a maltose binding protein tag polypeptide.

64. The isolated nucleic acid of claim 60, said nucleic acid further comprising a nucleic acid specifying a promoter/regulatory sequence operably linked thereto.

65. A vector comprising the isolated nucleic acid of claim 60.

66. The vector of claim 65, said vector further comprising a nucleic acid specifying a promoter/regulatory sequence operably linked thereto.

67. A recombinant cell comprising the isolated nucleic acid of claim

60.

l-PH/1977697.1 90

68. A recombinant cell comprising the vector of claim 65.

69. An isolated nucleic acid complementary to a nucleic acid encoding the Y372C mutant FGFRl set forth in SEQ ID NO:l, said complementary nucleic acid being in an antisense orientation.

70. A vector comprising the isolated nucleic acid of claim 69.

71. The vector of claim 70, said vector further comprising a nucleic acid specifying a promoter/regulatory sequence operably linked thereto.

72. A recombinant cell comprising the isolated nucleic acid of claim 69.

73. A transgenic non-human mammal comprising an isolated nucleic acid encoding a Y372C mutant FGFRl set forth in SEQ ID NO:2.

74. An isolated polypeptide comprising the Y372C FGFRl mutant protein set forth in SEQ ID NO:2.

75. An isolated antibody that specifically binds with the Y372C FGFRl mutant protein set forth in SEQ ID NO:2.

76. The antibody of claim 75, wherein said antibody is selected from the group consisting of a polyclonal antibody, a monoclonal antibody, a humanized antibody, a chimeric antibody, and a synthetic antibody.

77. A composition comprising the polypeptide of claim 74, or a fragment thereof, and a pharmaceutically-acceptable carrier.

78. A method of identifying a compound that modulates a phosphate homeostasis disorder in a cell, said method comprising contacting a cell with a test

l-PH/1977697 1 g ^"compo nd known to bind^' FGFRl and comparing the severity of the phosphate homeostasis disorder in said cell with the severity of a phosphate homeostasis disorder in an otherwise identical cell not contacted with said test compound, wherein a greater or lesser severity of the phosphate homeostasis disorder in said cell contacted with said test compound compared with the severity of a phosphate homeostasis disorder in said otherwise identical cell not contacted with said test compound is an indication that said test compound binds FGFRl in a cell, thereby identifying a compound that modulates a phosphate homeostasis disorder in a cell.

79. A compound identified by the method of claim 78.

l-PH/1977697.1 92