WO2003038094A1 - Regulation du transporteur de glucose humain - Google Patents

Regulation du transporteur de glucose humain Download PDF

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Publication number
WO2003038094A1
WO2003038094A1 PCT/EP2002/012058 EP0212058W WO03038094A1 WO 2003038094 A1 WO2003038094 A1 WO 2003038094A1 EP 0212058 W EP0212058 W EP 0212058W WO 03038094 A1 WO03038094 A1 WO 03038094A1
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glucose transporter
polynucleotide
polypeptide
activity
glucose
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PCT/EP2002/012058
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English (en)
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Yonghong Xiao
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Bayer Healthcare Ag
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
    • C07K14/435—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from animals; from humans
    • C07K14/705—Receptors; Cell surface antigens; Cell surface determinants

Definitions

  • the invention relates to the regulation of human glucose transporter.
  • amino acid sequences which are at least about 61% identical to the amino acid sequence shown in SEQ ID NO: 2; and the amino acid sequence shown in SEQ ID NO: 2.
  • Yet another embodiment of the invention is a method of screening for agents which decrease extracellular matrix degradation.
  • a test compound is contacted with a glucose transporter polypeptide comprising an amino acid sequence selected from the group consisting of:
  • amino acid sequences which are at least about 61% identical to the amino acid sequence shown in SEQ ID NO: 2; and the amino acid sequence shown in SEQ ID NO: 2.
  • a test compound which binds to the glucose transporter polypeptide is thereby identified as a potential agent for decreasing extracellular matrix degradation.
  • the agent can work by decreasing the activity of the glucose transporter.
  • Another embodiment of the invention is a method of screening for agents which decrease extracellular matrix degradation.
  • a test compound is contacted with a poly- nucleotide encoding a glucose transporter polypeptide, wherein the polynucleotide comprises a nucleotide sequence selected from the group consisting of:
  • nucleotide sequences which are at least about 50% identical to the nucleotide sequence shown in SEQ ID NO: 1; and the nucleotide sequence shown in SEQ ID NO: 1.
  • a test compound which binds to the polynucleotide is identified as a potential agent for decreasing extracellular matrix degradation.
  • the agent can work by decreasing the amount of the glucose transporter through interacting with the glucose transporter mRNA.
  • Another embodiment of the invention is a method of screening for agents which regulate extracellular matrix degradation.
  • a test compound is contacted with a glucose transporter polypeptide comprising an amino acid sequence selected from the group consisting of: amino acid sequences which are at least about 61% identical to the amino acid sequence shown in SEQ ID NO: 2; and the amino acid sequence shown in SEQ ID NO: 2.
  • a glucose transporter activity of the polypeptide is detected.
  • a test compound which increases glucose transporter activity of the polypeptide relative to glucose transporter activity in the absence of the test compound is thereby identified as a potential agent for increasing extracellular matrix degradation.
  • a test compound which decreases glucose transporter activity of the polypeptide relative to glucose transporter activity in the absence of the test compound is thereby identified as a potential agent for decreasing extracellular matrix degradation.
  • Yet another embodiment of the invention is a method of screening for agents which decrease extracellular matrix degradation.
  • a test compound is contacted with a glucose transporter product of a polynucleotide which comprises a nucleotide sequence selected from the group consisting of:
  • nucleotide sequences which are at least about 50% identical to the nucleotide sequence shown in SEQ ID NO: 1; and the nucleotide sequence shown in SEQ ID NO: 1.
  • Binding of the test compound to the glucose transporter product is detected.
  • a test compound which binds to the glucose transporter product is thereby identified as a potential agent for decreasing extracellular matrix degradation.
  • Still another embodiment of the invention is a method of reducing extracellular matrix degradation.
  • a cell is contacted with a reagent which specifically binds to a polynucleotide encoding a glucose transporter polypeptide or the product encoded by the polynucleotide, wherein the polynucleotide comprises a nucleotide sequence selected from the group consisting of: nucleotide sequences which are at least about 50% identical to the nucleotide sequence shown in SEQ ID NO: 1; and the nucleotide sequence shown in SEQ ID NO: 1.
  • Glucose transporter activity in the cell is thereby decreased.
  • the invention thus provides a human glucose transporter that can be used to identify test compounds that may act, for example, as activators or inhibitors.
  • Human glucose transporter and fragments thereof also are useful in raising specific antibodies that can block the transporter and effectively reduce its activity.
  • Fig. 1 shows the DNA-sequence encoding a glucose transporter Polypeptide (SEQ ID NO: 1).
  • Fig. 2 shows the amino acid sequence deduced from the DNA-sequence of Fig.1 (SEQ LD NO: 2).
  • Fig. 3 shows the amino acid sequence of the protein identified by swissnew
  • Fig. 4 shows the BLASTP - alignment of 554_protein (SEQ ID NO: 2)against swissnew
  • Fig. 5 shows the HMMPFAM - alignment of 554_protein (SEQ ID NO: 2) against pfam
  • sugar_tr Sugar (and other) transporter. This hit is scoring at : 456.2; Expect 2.8e-133; Scoring matrix : BLOSUM62 (used to infer consensus pattern).
  • Fig. 6 shows the Gene Prediction.
  • the majority of this polynucleotide was constructed by running genewise with Rat Glucose Transporter type 5 with selected region of genomic clone AL356306.3 (lp36.23).
  • the first exon and the last 33 nucleotides of last exon are derived from enscan output of same genomic clone.
  • the exon/intron structure is shown as an alignment of LBRI_554_DNA (Q, SEQ ID NO: 1) with genomic clone AL356306.3 (H).
  • the invention relates to an isolated polynucleotide from the group consisting of:
  • amino acid sequences which are at least about 61% identical to the amino acid sequence shown in SEQ ID NO: 2; and the amino acid sequence shown in SEQ ID NO: 2.
  • a polynucleotide the sequence of which deviates from the polynucleotide sequences specified in (a) to (G) due to the degeneration of the genetic code and encodes a glucose transporter polypeptide; and e) a polynucleotide which represents a fragment, derivative or allelic variation of a polynucleotide sequence specified in (a) to (d) and encodes a glucose transporter polypeptide.
  • Human glucose transporter comprises the amino acid sequence shown in SEQ ID NO: 2.
  • a coding sequence for human glucose transporter is shown in SEQ ID NO: 1. This sequence is located on chromosome lp36.23.
  • Human glucose transporter is 60% identical over 491 amino acids to swissnew
  • SEQ ID NO: 2 contains prosite SUGAR_TRANSPORT_l and SUGAR_TRANSPORT_2 regions. It hits pfam
  • Human glucose transporter of the invention is expected to be useful for the same purposes as previously identified glucose transporters. Human glucose transporter is believed to be useful in therapeutic methods to treat disorders such as diabetes. Human glucose transporter also can be used to screen for human glucose transporter activators and inhibitors.
  • Human glucose transporter polypeptides according to the invention comprise at least 6, 10, 15, 20, 25, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 350, 400, 450,
  • a glucose transporter polypeptide of the invention therefore can be a portion of a glucose transporter protein, a full-length glucose transporter protein, or a fusion protein comprising all or a portion of a glucose transporter protein.
  • naturally or non-naturally occurring glucose transporter polypeptide variants have amino acid sequences which are at least about 61, 65, or 70, preferably about 75, 80, 85, 90, 96, 96, 98, or 99% identical to the amino acid sequence shown in SEQ ID NO: 2 or a fragment thereof. Percent identity between a putative glucose transporter polypeptide variant and an amino acid sequence of SEQ ID NO: 2 is determined by conventional methods. See, for example, Altschul et al., Bull. Math. Bio. 48:603
  • the trimmed initial regions are examined to determine whether the regions can be joined to for man approximate alignment with gaps.
  • FASTA can also be used to determine the sequence identity of nucleic acid molecules using a ratio as disclosed above.
  • the ktup value can range between one to six, preferably from three to six, most preferably three, with other parameters set as default.
  • Variations in percent identity can be due, for example, to amino acid substitutions, insertions, or deletions.
  • Amino acid substitutions are defined as one for one amino acid replacements. They are conservative in nature when the substituted amino acid has similar structural and/or chemical properties. Examples of conservative replacements are substitution of a leucine with an isoleucine or valine, an aspartate with a glutamate, or a threonine with a serine.
  • Amino acid insertions or deletions are changes to or within an amino acid sequence. They typically fall in the range of about 1 to 5 amino acids. Guidance in determining which amino acid residues can be substituted, inserted, or deleted without abolishing biological or immunological activity of a human glucose transporter polypeptide can be found using computer programs well known in the art, such as DNASTAR software.
  • the invention additionally, encompasses glucose transporter polypeptides that are differentially modified during or after translation, e.g., by glycosylation, acetylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, linkage to an antibody molecule or other cellular ligand, etc.
  • Additional post-translational modifications encompassed by the invention include, for example, e.g., N-linked or O-linked carbohydrate chains, processing of N- terminal or C-terminal ends), attachment of chemical moieties to the amino acid backbone, chemical modifications of N-linked or O-linked carbohydrate chains, and addition or deletion of an N-terminal methionine residue as a result of prokaryotic host cell expression.
  • the glucose transporter polypeptides may also be modified with a detectable label, such as an enzymatic, fluorescent, isotopic or affinity label to allow for detection and isolation of the protein.
  • the invention also provides chemically modified derivatives of glucose transporter polypeptides that may provide additional advantages such as increased solubility, stability and circulating time of the polypeptide, or decreased immunogenicity (see U.S. Patent No. 4,179,337).
  • the chemical moieties for derivitization can be selected from water soluble polymers such as polyethylene glycol, ethylene glycol/propylene glycol copolymers, carboxymethylcellulose, dextran, polyvinyl alcohol, and the like.
  • polypeptides can be modified at random or predetermined positions within the molecule and can include one, two, three, or more attached chemical moieties.
  • Whether an amino acid change or a polypeptide modification results in a biologically active glucose transporter polypeptide can readily be determined by assaying for sugar transporter activity, as described for example, in Cornford et al., Am J Physiol Heart Circ Physiol 2000 Sep;279(3):H1346-54.
  • Fusion proteins are useful for generating antibodies against glucose transporter polypeptide amino acid sequences and for use in various assay systems. For example, fusion proteins can be used to identify proteins that interact with portions of a human glucose transporter polypeptide. Protein affinity chromatography or library-based assays for protein-protein interactions, such as the yeast two-hybrid or phage display systems, can be used for this purpose. Such methods are well known in the art and also can be used as drug screens.
  • a human glucose transporter polypeptide fusion protein comprises two polypeptide segments fused together by means of a peptide bond.
  • the first polypeptide segment comprises at least 6, 10, 15, 20, 25, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 350, 400, 450, 500, or 512 contiguous amino acids of SEQ ID NO: 2 or of a biologically active variant, such as those described above.
  • the first polypeptide segment also can comprise full-length glucose transporter protein.
  • the second polypeptide segment can be a full-length protein or a protein fragment.
  • Proteins commonly used in fusion protein construction include ⁇ -galactosidase, ⁇ - glucuronidase, green fluorescent protein (GFP), autofluorescent proteins, including blue fluorescent protein (BFP), glutathione-S-transferase (GST), luciferase, horse- radish peroxidase (HRP), and chloramphenicol acetyltransferase (CAT).
  • epitope tags are used in fusion protein constructions, including histidine (His) tags, FLAG tags, influenza hemagglutinin (HA) tags, Myc tags, VSV-G tags, and thioredoxin (Trx) tags.
  • Other fusion constructions can include maltose binding protein (MBP), S-tag, Lex a DNA binding domain (DBD) fusions, GAL4 DNA binding domain fusions, and herpes simplex virus (HSV) BP16 protein fusions.
  • a fusion protein also can be engineered to contain a cleavage site located between the glucose transporter polypeptide-encoding sequence and the heterologous protein sequence, so that the glucose transporter polypeptide can be cleaved and purified away from the heterologous moiety.
  • a fusion protein can be synthesized chemically, as is known in the art.
  • a fusion protein is produced by covalently linking two polypeptide segments or by standard procedures in the art of molecular biology.
  • Recombinant DNA methods can be used to prepare fusion proteins, for example, by making a DNA construct which comprises coding sequences selected from SEQ LD NO: 1 in proper reading frame with nucleotides encoding the second polypeptide segment and expressing the DNA construct in a host cell, as is known in the art.
  • kits for constructing fusion proteins are available from companies such as Promega Corporation (Madison, Wi), Stratagene (La Jolla, CA), CLONTECH (Mountain View, CA), Santa Cruz Biotechnology (Santa Cruz, CA), MBL International Corporation (MIC; Watertown, MA), and Quantum Biotechnologies (Montreal, Canada; 1-888-DNA-KITS).
  • Species homologs of human glucose transporter polypeptide can be obtained using glucose transporter polypeptide polynucleotides (described below) to make suitable probes or primers for screening cDNA expression libraries from other species, such as mice, monkeys, or yeast, identifying cDNAs which encode homologs of glucose transporter polypeptide, and expressing the cDNAs as is known in the art.
  • a human glucose transporter polynucleotide can be single- or double-stranded and comprises a coding sequence or the complement of a coding sequence for a glucose transporter polypeptide.
  • a coding sequence for human glucose transporter is shown in SEQ ID NO: 1.
  • Degenerate nucleotide sequences encoding human glucose transporter polypeptides, as well as homologous nucleotide sequences which are at least about 50, 55, 60, 65, 70, preferably about 75, 90, 96, 98, or 99% identical to the nucleotide sequence shown in SEQ ID NO: 1 or its complement also are glucose transporter polynucleo- tides.
  • Percent sequence identity between the sequences of two polynucleotides is determined using computer programs such as ALIGN which employ the FASTA algorithm, using an affine gap search with a gap open penalty of -12 and a gap extension penalty of -2.
  • cDNA Complementary DNA
  • species homologs, and variants of glucose transporter polynucleotides that encode biologically active glucose transporter polypeptides also are glucose transporter polynucleotides.
  • Polynucleotide fragments comprising at least 8, 9, 10, 11, 12, 15, 20, or 25 contiguous nucleotides of SEQ ID NO: 1 or. its complement also are glucose transporter polynucleotides. These fragments can be used, for example, as hybridization probes or as antisense oligonucleotides.
  • Variants and homologs of the glucose transporter polynucleotides described above also are glucose transporter polynucleotides.
  • homologous glucose transporter polynucleotide sequences can be identified by hybridization of candidate polynucleotides to known glucose transporter polynucleotides under stringent conditions, as is known in the art.
  • homologous sequences can be identified which contain at most about 25-30% basepair mismatches. More preferably, homologous nucleic acid strands contain 15-25% basepair mismatches, even more preferably 5-15% basepair mismatches.
  • Species homologs of the glucose transporter polynucleotides disclosed herein also can be identified by making suitable probes or primers and screening cDNA expression libraries from other species, such as mice, monkeys, or yeast.
  • Human variants of glucose transporter polynucleotides can be identified, for example, by screening human cDNA expression libraries. It is well known that the T m of a double-stranded DNA decreases by 1-1.5°C with every 1% decrease in homology (Bonner et al., J. Mol. Biol. 81, 123 (1973).
  • Variants of human glucose transporter polynucleotides or glucose transporter polynucleotides of other species can therefore be identified by hybridizing a putative homologous glucose transporter polynucleotide with a polynucleotide having a nucleotide sequence of SEQ ID NO: 1 or the complement thereof to form a test hybrid.
  • the melting temperature of the test hybrid is compared with the melting temperature of a hybrid comprising polynucleotides having perfectly complementary nucleotide sequences, and the number or percent of basepair mismatches within the test hybrid is calculated.
  • Nucleotide sequences which hybridize to glucose transporter polynucleotides or their complements following stringent hybridization and/or wash conditions also are glucose transporter polynucleotides.
  • Stringent wash conditions are well known and understood in the art and are disclosed, for example, in Sambrook et al., MOLECULAR CLONING: A LABORATORY MANUAL, 2d ed., 1989, at pages 9.50-9.51.
  • T m of a hybrid between a glucose transporter polynucleotide having a nucleotide sequence shown in SEQ ID NO: 1 or the complement thereof and a polynucleotide sequence which is at least about 50, preferably about 75, 90, 96, or 98% identical to one of those nucleotide sequences can be calculated, for example, using the equation of Bolton and McCarthy, Proc. Natl. Acad. Sci. U.S.A. 48, 1390 (1962):
  • Stringent wash conditions include, for example, 4X SSC at 65°C, or 50% formamide, 4X SSC at 42°C, or 0.5X SSC, 0.1% SDS at 65°C.
  • Highly stringent wash conditions include, for example, 0.2X SSC at 65°C.
  • a human glucose transporter polynucleotide can be isolated free of other cellular components such as membrane components, proteins, and lipids.
  • Polynucleotides can be made by a cell and isolated using standard nucleic acid purification techniques, or synthesized using an amplification technique, such as the polymerase chain reaction (PCR), or by using an automatic synthesizer. Methods for isolating polynucleotides are routine and are known in the art. Any such technique for obtaining a polynucleotide can be used to obtain isolated glucose transporter poly- nucleotides. For example, restriction enzymes and probes can be used to isolate polynucleotide fragments, which comprise glucose transporter nucleotide sequences. Isolated polynucleotides are in preparations that are free or at least 70, 80, or 90% free of other molecules.
  • Human glucose transporter cDNA molecules can be made with standard molecular biology techniques, using glucose transporter mRNA as a template. Human glucose transporter cDNA molecules can thereafter be replicated using molecular biology techniques known in the art and disclosed in manuals such as Sambrook et al. (1989). An amplification technique, such as PCR, can be used to obtain additional copies of polynucleotides of the invention, using either human genomic DNA or cDNA as a template.
  • glucose transporter polynucleotides can be synthesized using synthetic chemistry techniques to synthesize glucose transporter polynucleotides.
  • the degeneracy of the genetic code allows alternate nucleotide sequences to be synthesized which will encode a human glucose transporter polypeptide having, for example, an amino acid sequence shown in SEQ ID NO: 2 or a biologically active variant thereof.
  • PCR-based methods can be used to extend the nucleic acid sequences disclosed herein to detect upstream sequences such as promoters and regulatory elements.
  • restriction-site PCR uses universal primers to retrieve unknown sequence adjacent to a known locus (Sarkar, PCR Methods Applic. 2, 318-322, 1993). Genomic DNA is first amplified in the presence of a primer to a linker sequence and a primer specific to the known region. The amplified sequences are then subjected to a second round of PCR with the same linker primer and another specific primer internal to the first one. Products of each round of PCR are transcribed with an appropriate RNA polymerase and sequenced using reverse transcriptase.
  • Inverse PCR also can be used to amplify or extend sequences using divergent primers based on a known region (Triglia et al., Nucleic Acids Res. 16, 8186, 1988).
  • Primers can be designed using commercially available software, such as OLIGO 4.06 Primer Analysis software (National Biosciences Inc., Madison, Minn.), to be 22-30 nucleotides in length, to have a GC content of 50% or more, and to anneal to the target sequence at temperatures about 68-72°C.
  • the method uses several restriction enzymes to generate a suitable fragment in the known region of a gene. The fragment is then circularized by intramolecular ligation and used as a PCR template.
  • capture PCR involves PCR amplification of DNA fragments adjacent to a known sequence in human and yeast artificial chromosome DNA (Lagerstrom et al., PCR Methods Applic. 1, 111-119, 1991).
  • multiple restriction enzyme digestions and ligations also can be used to place an engineered double-stranded sequence into an unknown fragment of the DNA molecule before performing PCR.
  • Another method which can be used to retrieve unknown sequences is that of Parker et al., Nucleic Acids Res. 19, 3055-3060, 1991).
  • PCR, nested primers, and PROMOTERFINDER libraries (CLONTECH, Palo Alto, Calif.) can be used to walk genomic DNA (CLONTECH, Palo Alto, Calif.). This process avoids the need to screen libraries and is useful in finding intron/exon junctions.
  • Randomly-primed libraries are preferable, in that they will contain more sequences which contain the 5' regions of genes. Use of a randomly primed library may be especially preferable for situations in which an oligo d(T) library does not yield a full-length cDNA. Genomic libraries can be useful for extension of sequence into 5' non-transcribed regulatory regions.
  • capillary electrophoresis systems can be used to analyze the size or confirm the nucleotide sequence of PCR or sequencing products.
  • capillary sequencing can employ flowable polymers for electrophoretic separation, four different fluorescent dyes (one for each nucleotide) that are laser activated, and detection of the emitted wavelengths by a charge coupled device camera.
  • Output/light intensity can be converted to electrical signal using appropriate software (e.g. GENOTYPER and Sequence NAVIGATOR, Perkin Elmer), and the entire process from loading of samples to computer analysis and electronic data display can be computer controlled.
  • Capillary electrophoresis is especially preferable for the sequencing of small pieces of DNA that might be present in limited amounts in a particular sample.
  • Glucose transporter polypeptides can be obtained, for example, by purification from human cells, by expression of glucose transporter polynucleotides, or by direct chemical synthesis. Protein purification
  • Glucose transporter polypeptides can be purified from any human cell which expresses the receptor, including host cells which have been transfected with glucose transporter polynucleotides.
  • a purified glucose transporter polypeptide is separated from other compounds that normally associate with the glucose transporter polypeptide in the cell, such as certain proteins, carbohydrates, or lipids, using methods well-known in the art. Such methods include, but are not limited to, size exclusion chromatography, ammonium sulfate fractionation, ion exchange chromatography, affinity chromatography, and preparative gel electrophoresis.
  • Glucose transporter polypeptide can be conveniently isolated as a complex with its associated G protein, as described in the specific examples, below.
  • a preparation of purified glucose transporter polypeptides is at least 80% pure; preferably, the preparations are 90%, 95%, or 99% pure. Purity of the preparations can be assessed by any means known in the art, such as SDS-polyacrylamide gel electrophoresis.
  • the polynucleotide can be inserted into an expression vector which contains the necessary elements for the transcription and translation of the inserted coding sequence.
  • Methods which are well known to those skilled in the art can be used to construct expression vectors containing sequences encoding glucose transporter polypeptides and appropriate transcriptional and translational control elements. These methods include in vitro recombinant DNA techniques, synthetic techniques, and in vivo genetic recombination. Such techniques are described, for example, in Sambrook et al. (1989) and in Ausubel et al, CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, John Wiley 8c Sons, New York, N.Y., 1989.
  • a variety of expression vector/host systems can be utilized to contain and express sequences encoding a human glucose transporter polypeptide. These include, but are not limited to, microorganisms, such as bacteria transformed with recombinant bacteriophage, plasmid, or cosmid DNA expression vectors; yeast transformed with yeast expression vectors, insect cell systems infected with virus expression vectors
  • virus expression vectors e.g., cauliflower mosaic virus, CaMV; tobacco mosaic virus, TMV
  • bacterial expression vectors e.g., Ti or pBR322 plasmids
  • control elements or regulatory sequences are those non-translated regions of the vector -- enhancers, promoters, 5' and 3' untranslated regions — which interact with host cellular proteins to carry out transcription and translation. Such elements can vary in their strength and specificity. Depending on the vector system and host utilized, any number of suitable transcription and translation elements, including constitutive and inducible promoters, can be used. For example, when cloning in bacterial systems, inducible promoters such as the hybrid lacZ promoter of the BLUESCRLPT phagemid (Stratagene, LaJolla, Calif.) or pSPORTl plasmid (Life Technologies) and the like can be used. The baculovirus polyhedrin promoter can be used in insect cells.
  • Promoters or enhancers derived from the genomes of plant cells e.g., heat shock, RUBISCO, and storage protein genes
  • plant viruses e.g., viral promoters or leader sequences
  • promoters from mammalian genes or from mammalian viruses are preferable. If it is necessary to generate a cell line that contains multiple copies of a nucleotide sequence encoding a human glucose transporter polypeptide, vectors based on SV40 or EBV can be used with an appropriate selectable marker.
  • a number of expression vectors can be selected depending upon the use intended for the glucose transporter polypeptide. For example, when a large quantity of a human glucose transporter polypeptide is needed for the induction of antibodies, vectors which direct high level expression of fusion proteins that are readily purified can be used. Such vectors include, but are not limited to, multifunctional E. coli cloning and expression vectors such as BLUES CREPT (Stratagene). In a BLUESCRIPT vector, a sequence encoding the glucose transporter polypeptide can be ligated into the vector in frame with sequences for the amino-terminal Met and the subsequent 7 residues of ⁇ -galactosidase so that a hybrid protein is produced.
  • BLUESCRIPT vector a sequence encoding the glucose transporter polypeptide can be ligated into the vector in frame with sequences for the amino-terminal Met and the subsequent 7 residues of ⁇ -galactosidase so that a hybrid protein is produced.
  • pIN vectors Van Heeke & Schuster, J Biol. Chem. 264, 5503-5509, 1989
  • pGEX vectors Promega, Madison, Wis.
  • GST glutathione S-transferase
  • fusion proteins are soluble and can easily be purified from lysed cells by adsorption to glutathione-agarose beads followed by elution in the presence of free glutathione.
  • Proteins made in such systems can be designed to include heparin, thrombin, or factor Xa protease cleavage sites so that the cloned polypeptide of interest can be released from the GST moiety at will.
  • yeast Saccharomyces cerevisiae a number of vectors containing constitutive or inducible promoters such as alpha factor, alcohol oxidase, and PGH can be used.
  • constitutive or inducible promoters such as alpha factor, alcohol oxidase, and PGH.
  • the expression of sequences encoding glucose transporter polypeptides can be driven by any of a number of promoters.
  • viral promoters such as the 35S and 19S promoters of CaMV can be used alone or in combination with the omega leader sequence from TMV (Takamatsu, EMBO J. 6, 307-311, 1987).
  • plant promoters such as the small subunit of RUBISCO or heat shock promoters can be used (Coruzzi et al, EMBO J. 3, 1671-1680, 1984; Broglie et al., Science 224, 838-843, 1984; Winter et al, Results Probl. Cell Differ. 17, 85-105, 1991).
  • constructs can be introduced into plant cells by direct DNA transformation or by pathogen-mediated transfection.
  • pathogen-mediated transfection Such techniques are described in a number of generally available reviews (e.g., Hobbs or Murray, in MCGRAW HILL YEARBOOK OF SCIENCE AND TECHNOLOGY, McGraw Hill, New York, N ., pp. 191-196, 1992).
  • An insect system also can be used to express a human glucose transporter polypeptide.
  • Autographa californica nuclear poly- hedrosis virus (AcNPV) is used as a vector to express foreign genes in Spodoptera frugiperda cells or in Trichoplusia larvae.
  • Sequences encoding glucose transporter polypeptides can be cloned into a non-essential region of the virus, such as the polyhedrin gene, and placed under control of the polyhedrin promoter.
  • Successful insertion of glucose transporter polypeptides will render the polyhedrin gene inactive and produce recombinant virus lacking coat protein.
  • the recombinant viruses can then be used to infect S. frugiperda cells or Trichoplusia larvae in which glucose transporter polypeptides can be expressed (Engelhard et al, Proc. Nat. Acad. Sci. 91, 3224-3227, 1994).
  • a number of viral-based expression systems can be used to express glucose transporter polypeptides in mammalian host cells.
  • sequences encoding glucose transporter polypeptides can be ligated into an adenovirus transcription/translation complex comprising the late promoter and tripartite leader sequence. Insertion in a non-essential El or E3 region of the viral genome can be used to obtain a viable virus which is capable of expressing a human glucose transporter polypeptide in infected host cells (Logan &
  • transcription enhancers such as the Rous sarcoma virus (RSV) enhancer, can be used to increase expression in mammalian host cells.
  • RSV Rous sarcoma virus
  • HACs Human artificial chromosomes
  • 6M to 10M are constructed and delivered to cells via conventional delivery methods (e.g., liposomes, polycationic amino polymers, or vesicles).
  • Specific initiation signals also can be used to achieve more efficient translation of sequences encoding glucose transporter polypeptides. Such signals include the ATG initiation codon and adjacent sequences. In cases where sequences encoding a human glucose transporter polypeptide, its initiation codon, and upstream sequences are inserted into the appropriate expression vector, no additional transcriptional or translational control signals may be needed. However, in cases where only coding sequence, or a fragment thereof, is inserted, exogenous translational control signals
  • initiation codon should be provided.
  • the initiation codon should be in the correct reading frame to ensure translation of the entire insert.
  • Exogenous translational elements and initiation codons can be of various origins, both natural and synthetic. The efficiency of expression can be enhanced by the inclusion of enhancers which are appropriate for the particular cell system which is used (see Sc arf et al, Results Probl. Cell Differ. 20, 125-162, 1994).
  • a host cell strain can be chosen for its ability to modulate the expression of the inserted sequences or to process the expressed glucose transporter polypeptide in the desired fashion.
  • modifications of the polypeptide include, but are not limited to, acetylation, carboxylation, glycosylation, phosphorylation, lipidation, and acylation.
  • Post-translational processing which cleaves a "prepro" form of the poly- peptide also can be used to facilitate correct insertion, folding and/or function.
  • Different host cells that have specific cellular machinery and characteristic mechanisms for post-translational activities are available from the American Type Culture Collection (ATCC; 10801 University Boulevard, Manassas, VA 20110-2209) and can be chosen to ensure the correct modification and processing of the foreign protein. Stable expression is preferred for long-term, high-yield production of recombinant proteins.
  • cell lines which stably express glucose transporter polypeptides can be transformed using expression vectors which can contain viral origins of replication and or endogenous expression elements and a selectable marker gene on the same or on a separate vector.
  • cells can be allowed to grow for 1-2 days in an enriched medium before they are switched to a selective medium.
  • the purpose of the selectable marker is to confer resistance to selection, and its presence allows growth and recovery of cells which successfully express the introduced glucose transporter sequences.
  • Resistant clones of stably transformed cells can be proliferated using tissue culture techniques appropriate to the cell type. See, for example, ANIMAL CELL CULTURE, R.I. Freshney, ed., 1986.
  • Any number of selection systems can be used to recover transformed cell lines. These include, but are not limited to, the herpes simplex virus thymidine kinase
  • dhfr confers resistance to methotrexate (Wigler et al, Proc. Natl. Acad. Sci. 77, 3567-70, 1980)
  • npt confers resistance to the aminoglycosides, neomycin and G-418 (Colbere-Garapin et al, J. Mol. Biol.
  • trpB allows cells to utilize indole in place of tryptophan, or hisD, which allows cells to utilize histinol in place of histidine
  • Visible markers such as anthocyanins, ⁇ -glucuronidase and its substrate GUS, and luciferase and its substrate luciferin, can be used to identify transformants and to quantify the amount of transient or stable protein expression attributable to a specific vector system (Rhodes et al, Methods Mol. Biol. 55, 121-131, 1995). Detecting expression
  • marker gene expression suggests that the glucose transporter polynucleotide is also present, its presence and expression may need to be confirmed. For example, if a sequence encoding a human glucose transporter polypeptide is inserted within a marker gene sequence, transformed cells containing sequences which encode an glucose transporter polypeptide can be identified by the absence of marker gene function. Alternatively, a marker gene can be placed in tandem with a sequence encoding an glucose transporter polypeptide under the control of a single promoter. Expression of the marker gene in response to induction or selection usually indicates expression of the glucose transporter polynucleotide.
  • host cells which contain a human glucose transporter polynucleotide and which express a human glucose transporter polypeptide can be identified by a variety of procedures known to those of skill in the art. These procedures include, but are not limited to, DNA-DNA or DNA-RNA hybridizations and protein bioassay or immunoassay techniques that include membrane, solution, or chip-based technologies for the detection and/or quantification of nucleic acid or protein. For example, the presence of a polynucleotide sequence encoding an glucose transporter polypeptide can be detected by DNA-DNA or DNA-RNA hybridization or amplification using probes or fragments or fragments of polynucleotides encoding a human glucose transporter polypeptide. Nucleic acid amplification-based assays involve the use of oligonucleotides selected from sequences encoding an glucose transporter polypeptide to detect transformants which contain. an glucose transporter polynucleotide.
  • a variety of protocols for detecting and measuring the expression of a human glucose transporter polypeptide, using either polyclonal or monoclonal antibodies specific for the polypeptide, are known in the art. Examples include enzyme-linked immuno- sorbent assay (ELISA), radioimmunoassay (RIA), and fluorescence activated cell sorting (FACS).
  • ELISA enzyme-linked immuno- sorbent assay
  • RIA radioimmunoassay
  • FACS fluorescence activated cell sorting
  • a two-site, monoclonal-based immunoassay using monoclonal anti- bodies reactive to two non-interfering epitopes on a human glucose transporter polypeptide can be used, or a competitive binding assay can be employed. These and other assays are described in Hampton et al, SEROLOGICAL METHODS: A LABORATORY MANUAL, APS Press, St. Paul, Minn., 1990) and Maddox et al, J. Exp. Med. 158,
  • RNA polymerase a DNA sequence that is derived from a source of RNA sequences.
  • Means for producing labeled hybridization or PCR probes for detecting sequences related to polynucleotides encoding glucose transporter polypeptides include oligolabeling, nick translation, end-labeling, or PCR amplification using a labeled nucleotide.
  • sequences encoding a human glucose transporter polypeptide can be cloned into a vector for the production of an mRNA probe.
  • Such vectors are known in the art, are commercially available, and can be used to synthesize RNA probes in vitro by addition of labeled nucleotides and an appropriate RNA polymerase such as
  • T7, T3, or SP6 procedures can be conducted using a variety of commercially available kits (Amersham Pharmacia Biotech, Promega, and US Biochemical), Suitable reporter molecules or labels which can be used for ease of detection include radionuclides, enzymes, and fluorescent, chemiluminescent, or chromogenic agents, as well as substrates, cofactors, inhibitors, magnetic particles, and the like.
  • Host cells transformed with nucleotide sequences encoding a human glucose transporter polypeptide can be cultured under conditions suitable for the expression and recovery of the protein from cell culture.
  • the polypeptide produced by a transformed cell can be secreted or contained intracellularly depending on the sequence and/or the vector used.
  • expression vectors containing polynucleotides which encode glucose transporter polypeptides can be designed to contain signal sequences which direct secretion of soluble glucose transporter polypeptides through a prokaryotic or eukaryotic cell membrane or which direct the membrane insertion of membrane-bound glucose transporter polypeptide.
  • purification facilitating domains include, but are not limited to, metal chelating peptides such as histidine-tryptophan modules that allow purification on immobilized metals, protein A domains that allow purification on immobilized immunoglobulin, and the domain utilized in the FLAGS extension/affinity purification system
  • cleavable linker sequences such as those specific for Factor Xa or enterokinase (Invitrogen, San Diego, CA) between the purification domain and the glucose transporter polypeptide also can be used to facilitate purification.
  • One such expression vector provides for expression of a fusion protein containing a human glucose transporter polypeptide and 6 histidine residues preceding a thioredoxin or an enterokinase cleavage site. The histidine residues facilitate purification by LMAC (immobilized metal ion affinity chromatography, as described in Porath et al, Prot. Exp. Purif.
  • enterokinase cleavage site provides a means for purifying the glucose transporter polypeptide from the fusion protein.
  • Vectors that contain fusion proteins are disclosed in Kroll et al, DNA Cell Biol. 12, 441-453, 1993.
  • Sequences encoding a human glucose transporter polypeptide can be synthesized, in whole or in part, using chemical methods well known in the art (see Caruthers et al, Nucl. Acids Res. Symp. Ser. 215-223, 1980; Horn et al Nucl. Acids Res. Symp. Ser. 225-232, 1980).
  • a human glucose transporter polypeptide itself can be produced using chemical methods to synthesize its amino acid sequence, such as by direct peptide synthesis using solid-phase techniques (Merrifield, J Am. Chem. Soc.
  • Protein synthesis can be performed using manual techniques or by automation. Automated synthesis can be achieved, for example, using Applied Biosystems 431 A Peptide Synthesizer (Perkin Elmer).
  • fragments of glucose transporter polypeptides can be separately synthesized and combined using chemical methods to produce a full- length molecule.
  • the newly synthesized peptide can be substantially purified by preparative high performance liquid chromatography (e.g., Creighton, PROTEINS: STRUCTURES AND MOLECULAR PRINCIPLES, WH Freeman and Co., New York, NY., 1983).
  • the composition of a synthetic glucose transporter polypeptide can be confirmed by amino acid analysis or sequencing (e.g., the Edman degradation procedure; see Creighton, supra). Additionally, any portion of the amino acid sequence of the glucose transporter polypeptide can be altered during direct synthesis and/or combined using chemical methods with sequences from other proteins to produce a variant polypeptide or a fusion protein.
  • codons preferred by a particular prokaryotic or eukaryotic host can be selected to increase the rate of protein expression or to produce an RNA transcript having desirable properties, such as a half-life which is longer than that of a transcript generated from the naturally occurring sequence.
  • nucleotide sequences disclosed herein can be engineered using methods generally known in the art to alter glucose transporter polypeptide-encoding sequences for a variety of reasons, including but not limited to, alterations which modify the cloning, processing, and or expression of the polypeptide or mRNA product.
  • DNA shuffling by random fragmentation and PCR reassembly of gene fragments and synthetic oligonucleotides can be used to engineer the nucleotide sequences.
  • site-directed mutagenesis can be used to insert new restriction sites, alter glycosylation patterns, change codon preference, produce splice variants, introduce mutations, and so forth.
  • Antibody as used herein includes intact immunoglobulin molecules, as well as fragments thereof, such as Fab, F(ab') 2 , and Fv, which are capable of binding an epitope of a human glucose transporter polypeptide.
  • Fab fragment antigen binding protein
  • F(ab') 2 fragment antigen binding protein
  • Fv fragment antigen binding protein
  • epitopes which involve non-contiguous amino acids may require more, e.g., at least 15, 25, or 50 amino acids.
  • An antibody which specifically binds to an epitope of a human glucose transporter polypeptide can be used therapeutically, as well as in immunochemical assays, such as Western blots, ELISAs, radioimmunoassays, immunohistochemical assays, immunoprecipitations, or other immunochemical assays known in the art.
  • immunochemical assays such as Western blots, ELISAs, radioimmunoassays, immunohistochemical assays, immunoprecipitations, or other immunochemical assays known in the art.
  • Various immunoassays can be used to identify antibodies having the desired specificity.
  • Such immunoassays typically involve the measurement of complex formation between an immunogen and an antibody that specifically binds to the immunogen.
  • an antibody which specifically binds to a human glucose transporter polypeptide provides a detection signal at least 5-, 10-, or 20-fold higher than a detection signal provided with other proteins when used in an immunochemical assay.
  • antibodies which specifically bind to glucose transporter polypeptides do not detect other proteins in immunochemical assays and can irrimuno- precipitate a human glucose transporter polypeptide from solution.
  • Human glucose transporter polypeptides can be used to immunize a mammal, such as a mouse, rat, rabbit, guinea pig, monkey, or human, to produce polyclonal antibodies.
  • a human glucose transporter polypeptide can be conjugated to a carrier protein, such as bovine serum albumin, thyroglobulin, and keyhole limpet hemocyanin.
  • a carrier protein such as bovine serum albumin, thyroglobulin, and keyhole limpet hemocyanin.
  • various adjuvants can be used to increase the immunological response.
  • adjuvants include, but are not limited to, Freund's adjuvant, mineral gels (e.g., aluminum hydroxide), and surface active substances (e.g. lysolecithin, pluronic polyols, polyanions, peptides, oil emulsions, keyhole limpet hemocyanin, and dinitrophenol).
  • BCG Bacilli Calmette-Gueri
  • Corynebacterium parvum are especially useful.
  • Monoclonal antibodies which specifically bind to a human glucose transporter polypeptide can be prepared using any technique which provides for the production of antibody molecules by continuous cell lines in culture. These techniques include, but are not limited to, the hybridoma technique, the human B-cell hybridoma technique, and the EBV-hybridoma technique (Kohler et al, Nature 256, 495-497, 1985; Kozbor et al, J. Immunol. Methods 81, 31-42, 1985; Cote et al, Proc. Natl. Acad. Sci. 80, 2026-2030, 1983; Cole et al, Mol. Cell Biol. 62, 109-120, 1984).
  • chimeric antibodies the splicing of mouse antibody genes to human antibody genes to obtain a molecule with appropriate antigen specificity and biological activity, can be used (Morrison et al, Proc. Natl. Acad. Sci. 81, 6851-6855, 1984; Neuberger et al, Nature 312, 604-608, 1984; Takeda et al, Nature 314, 452-454, 1985).
  • Monoclonal and other antibodies also can be "humanized” to prevent a patient from mounting an immune response against the antibody when it is used therapeutically. Such antibodies may be sufficiently similar in sequence to human antibodies to be used directly in therapy or may require alteration of a few key residues.
  • sequence differences between rodent antibodies and human sequences can be n ⁇ nized by replacing residues which differ from those in the human sequences by site directed mutagenesis of individual residues or by grating of entire complementarity determining regions.
  • humanized antibodies can be produced using recombinant methods, as described in GB2188638B.
  • Antibodies that specifically bind to a human glucose transporter polypeptide can contain antigen binding sites which are either partially or fully humanized, as disclosed in U.S. 5,565,332.
  • single chain antibodies can be adapted using methods known in the art to produce single chain antibodies that specifically bind to glucose transporter polypeptides.
  • Antibodies with related specificity, but of distinct idiotypic composition can be generated by chain shuffling from random combinatorial immunoglobin libraries (Burton, Proc. Natl. Acad. Sci.
  • Single-chain antibodies also can be constructed using a DNA amplification method, such as PCR, using hybridoma cDNA as a template (Thirion et al, 1996, Eur. J. Cancer Prev. 5, 507-11).
  • Single-chain antibodies can be mono- or bispecific, and can be bivalent or tetravalent. Construction of tetravalent, bispecific single-chain antibodies is taught, for example, in Coloma & Morrison, 1997, Nat. Biotechnol. 15, 159-63. Construction of bivalent, bispecific single-chain antibodies is taught in Mallender & Noss, 1994, J. Biol. Chem. 269, 199-206.
  • a nucleotide sequence encoding a single-chain antibody can be constructed using manual or automated nucleotide synthesis, cloned into an expression construct using standard recombinant D ⁇ A methods, and introduced into a cell to express the coding sequence, as described below.
  • single-chain antibodies can be pro- prised directly using, for example, filamentous phage technology (Verhaar et al,
  • Antibodies which specifically bind to glucose transporter polypeptides also can be produced by inducing in vivo production in the lymphocyte population or by screening irnmunoglobulin libraries or panels of highly specific binding reagents as disclosed in the literature (Orlandi et al, Proc. Natl. Acad. Sci. 86, 3833-3837, 1989; Winter et al, Nature 349, 293-299, 1991).
  • chimeric antibodies can be constructed as disclosed in
  • Binding proteins which are derived from immunoglobulins and which are multivalent and multispecific, such as the "diabodies" described in WO 94/13804, also can be prepared.
  • Antibodies according to the invention can be purified by methods well known in the art. For example, antibodies can be affinity purified by passage over a column to which a human glucose transporter polypeptide is bound. The bound antibodies can then be eluted from the column using a buffer with a high salt concentration.
  • Antisense oligonucleotides are nucleotide sequences which are complementary to a specific DNA or RNA sequence. Once introduced into a cell, the complementary nucleotides combine with natural sequences produced by the cell to form complexes and block either transcription or translation. Preferably, an antisense oligonucleotide is at least 11 nucleotides in length, but can be at least 12, 15, 20, 25, 30, 35, 40, 45, or 50 or more nucleotides long. Longer sequences also can be used. Antisense oligonucleotide molecules can be provided in a DNA construct and introduced into a cell as described above to decrease the level of glucose transporter gene products in the cell.
  • Antisense oligonucleotides can be deoxyribonucleotides, ribonucleotides, or a combination of both. Oligonucleotides can be synthesized manually or by an automated synthesizer, by covalently linking the 5' end of one nucleotide with the 3' end of another nucleotide with non-phosphodiester internucleotide linkages such alkyl- phosphonates, phosphorothioates, phosphorodithioates, alkylphosphonothioates, alkylphosphonates, phosphoramidates, phosphate esters, carbamates, acetamidate, carboxymethyl esters, carbonates, and phosphate rriesters. See Brown, Meth. Mol. Biol. 20, 1-8, 1994; Sonveaux, Meth. Mol Biol. 26, 1-72, 1994; Uhlmann et al, Chem. Rev. 90, 543-583, 1990.
  • Modifications of glucose transporter gene expression can be obtained by designing antisense oligonucleotides that will form duplexes to the control, 5', or regulatory regions of the glucose transporter gene. Oligonucleotides derived from the transcription initiation site, e.g., between positions -10 and +10 from the start site, are preferred. Similarly, inhibition can be achieved using "triple helix" base-pairing methodology. Triple helix pairing is useful because it causes inhibition of the ability of the double helix to open sufficiently for the binding of polymerases, transcription factors, or chaperons.
  • An antisense oligonucleotide also can be designed to block translation of mRNA by preventing the transcript from binding to ribosomes.
  • Antisense oligonucleotides which comprise, for example,
  • each stretch of complementary contiguous nucleotides is at least
  • Non-complementary intervening sequences are preferably 1, 2, 3, or 4 nucleotides in length.
  • One skilled in the art can easily use the calculated melting point of an antisense-sense pair to determine the degree of mismatching which will be tolerated between a particular antisense oligonucleotide and a particular glucose transporter polynucleotide sequence.
  • Antisense oligonucleotides can be modified without affecting their ability to hybridize to a human glucose transporter polynucleotide. These modifications can be internal or at one or both ends of the antisense molecule.
  • inter- nucleoside phosphate linkages can be modified by adding cholesteryl or diamine moieties with varying numbers of carbon residues between the amino groups and terminal ribose.
  • Modified bases and/or sugars such as arabinose instead of ribose, or a V, 5'-substituted oligonucleotide in which the 3' hydroxyl group or the 5' phosphate group are substituted, also can be employed in a modified antisense oligonucleotide.
  • modified oligonucleotides can be prepared by methods well known in the art. See, e.g., Agrawal et al, Trends Biotechnol. 10, 152-158, 1992; Uhlmann et al, Chem. Rev. 90, 543-584, 1990; Uhlmann et al, Tetrahedron. Lett. 215, 3539-3542, 1987.
  • Ribozymes are RNA molecules with catalytic activity. See, e.g., Cech, Science 236, 1532-1539; 1987; Cech, Ann. Rev. Biochem. 59, 543-568; 1990, Cech, Curr. Opin. Struct. Biol. 2, 605-609; 1992, Couture & Stinchcomb, Trends Genet. 12, 510-515, 1996. Ribozymes can be used to inhibit gene function by cleaving an RNA sequence, as is known in the art (e.g., Haseloff et al, U.S. Patent 5,641,673).
  • ribozyme action involves sequence-specific hybridization of the ribozyme molecule to complementary target RNA, followed by endonucleolytic cleavage.
  • Examples include engineered hammerhead motif ribozyme molecules that can specifically and efficiently catalyze endonucleolytic cleavage of specific nucleotide sequences.
  • the coding sequence of a human glucose transporter polynucleotide can be used to generate ribozymes that will specifically bind to mRNA transcribed from the glucose transporter polynucleotide.
  • Methods of designing and constructing ribozymes which can cleave other RNA molecules in trans in a highly sequence specific manner have been developed and described in the art (see Haseloff et al Nature 334, 585-591, 1988).
  • the cleavage activity of ribozymes can be targeted to specific RNAs by engineering a discrete "hybridization" region into the ribozyme.
  • the hybridization region contains a sequence complementary to the target RNA and thus specifically hybridizes with the target (see, for example, Gerlach et al, EP 321,201).
  • Specific ribozyme cleavage sites within a human glucose transporter RNA target can be identified by scanning the target molecule for ribozyme cleavage sites which include the following sequences: GUA, GUU, and GUC. Once identified, short RNA sequences of between 15 and 20 ribonucleotides corresponding to the region of the target RNA containing the cleavage site can be evaluated for secondary structural features which may render the target inoperable. Suitability of candidate glucose transporter RNA targets also can be evaluated by testing accessibility to hybridization with complementary oligonucleotides using ribonuclease protection assays. Longer complementary sequences can be used to increase the affinity of the hybridization sequence for the target. The hybridizing and cleavage regions of the ribozyme can be integrally related such that upon hybridizing to the target RNA through the complementary regions, the catalytic region of the ribozyme can cleave the target.
  • Ribozymes can be introduced into cells as part of a DNA construct. Mechanical methods, such as microinjection, liposome-mediated transfection, elecfroporation, or calcium phosphate precipitation, can be used to introduce a ribozyme-containing DNA construct into cells in which it is desired to decrease glucose transporter expression. Alternatively, if it is desired that the cells stably retain the DNA construct, the construct can be supplied on a plasmid and maintained as a separate element or integrated into the genome of the cells, as is known in the art.
  • a ribozyme-encoding DNA construct can include transcriptional regulatory elements, such as a promoter element, an enhancer or UAS element, and a transcriptional terminator signal, for controlling transcription of ribozymes in the cells.
  • ribozymes can be engineered so that ribozyme expression will occur in response to factors that induce expression of a target gene. Ribozymes also can be engineered to provide an additional level of regulation, so that destruction of mRNA occurs only when both a ribozyme and a target gene are induced in the cells.
  • genes whose products interact with human glucose transporter may represent genes that are differentially expressed in disorders including, but not limited to, diabetes. Further, such genes may represent genes that are differentially regulated in response to manipulations relevant to the progression or treatment of such diseases. Additionally, such genes may have a temporally modulated expression, increased or decreased at different stages of tissue or organism development. A differentially expressed gene may also have its expression modulated under control versus experimental conditions. In addition, the human glucose transporter gene or gene product may itself be tested for differential expression.
  • the degree to which expression differs in a normal versus a diseased state need only be large enough to be visualized via standard characterization techniques such as differential display techniques.
  • standard characterization techniques such as differential display techniques.
  • Other such standard characterization techniques by which expression differences may be visualized include but are not limited to, quantitative RT (reverse transcriptase), PCR, and Northern analysis.
  • RNA samples are obtained from tissues of experimental subjects and from corresponding tissues of control subjects. Any RNA isolation technique that does not select against the isolation of mRNA may be utilized for the purification of such RNA samples. See, for example, Ausubel et al, ed., CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, John Wiley & Sons, Inc. New York, 1987-1993. Large numbers of tissue samples may readily be processed using techniques well known to those of skill in the art, such as, for example, the single-step RNA isolation process of Chomczynski, U.S. Patent 4,843,155.
  • Transcripts within the collected RNA samples that represent RNA produced by differentially expressed genes are identified by methods well known to those of skill in the art. They include, for example, differential screening (Tedder et al, Proc. Natl. Acad. Sci. U.S.A. 85, 208-12, 1988), subfractive hybridization (Hedrick et al, Nature 308, 149-53; Lee et al, Proc. Natl. Acad. Sci. U.S.A. 88, 2825, 1984), and, preferably, differential display (Liang & Pardee, Science 257, 967-71, 1992; U.S.
  • the differential expression information may itself suggest relevant methods for the treatment of disorders involving the human glucose transporter.
  • treatment may include a modulation of expression of the differentially expressed genes and/or the gene encoding the human glucose transporter.
  • the differential expression information may indicate whether the expression or activity of the differentially expressed gene or gene product or the human glucose transporter gene or gene product are up-regulated or down-regulated.
  • the invention provides assays for screening test compounds that bind to or modulate the activity of a human glucose transporter polypeptide or a human glucose transporter polynucleotide.
  • a test compound preferably binds to a human glucose transporter polypeptide or polynucleotide. More preferably, a test compound decreases or increases enzymatic activity by at least about 10, preferably about 50, more preferably about 75, 90, or 100% relative to the absence of the test compound.
  • Test compounds preferably binds to a human glucose transporter polypeptide or polynucleotide. More preferably, a test compound decreases or increases enzymatic activity by at least about 10, preferably about 50, more preferably about 75, 90, or 100% relative to the absence of the test compound.
  • Test compounds can be pharmacologic agents already known in the art or can be compounds previously unknown to have any pharmacological activity.
  • the com- pounds can be naturally occurring or designed in the laboratory. They can be isolated from microorganisms, animals, or plants, and can be produced recom- binantly, or synthesized by chemical methods known in the art. If desired, test compounds can be obtained using any of the numerous combinatorial library methods known in the art, including but not limited to, biological libraries, spatially addressable parallel solid phase or solution phase libraries, synthetic library methods requiring deconvolution, the "one-bead one-compound” library method, and synthetic library methods using affinity chromatography selection.
  • the biological library approach is limited to polypeptide libraries, while the other four approaches are applicable to polypeptide, non-peptide oligomer, or small molecule libraries of compounds. See Lam, Anticancer Drug Des. 12, 145, 1997.
  • Test compounds can be screened for the ability to bind to glucose transporter polypeptides or polynucleotides or to affect glucose transporter activity or glucose transporter gene expression using high throughput screening. Using high throughput screening, many discrete compounds can be tested in parallel so that large numbers of test compounds can be quickly screened.
  • the most widely established techniques utilize 96-well microtiter plates. The wells of the microtiter plates typically require assay volumes that range from 50 to 500 ⁇ l. In addition to the plates, many instruments, materials, pipettors, robotics, plate washers, and plate readers are commercially available to fit the 96-well format.
  • free format assays or assays that have no physical barrier between samples, can be used.
  • an assay using pigment cells (melanocytes) in a simple homogeneous assay for combinatorial peptide libraries is described by
  • test samples are placed in a porous matrix.
  • One or more assay components are then placed within, on top of, or at the bottom of a matrix such as a gel, a plastic sheet, a filter, or other form of easily manipulated solid support.
  • a matrix such as a gel, a plastic sheet, a filter, or other form of easily manipulated solid support.
  • the test compound is preferably a small molecule that binds to the glucose transporter polypeptide, such that normal biological activity is prevented.
  • small molecules include, but are not limited to, small peptides or peptide-like molecules.
  • either the test compound or the glucose transporter polypeptide can comprise a detectable label, such as a fluorescent, radioisotopic, chemilumi- nescent, or enzymatic label, such as horseradish peroxidase, alkaline phosphatase, or luciferase. Detection of a test compound that is bound to the glucose transporter polypeptide can then be accomplished, for example, by direct counting of radio- emmission, by scintillation counting, or by determining conversion of an appropriate substrate to a detectable product.
  • a detectable label such as a fluorescent, radioisotopic, chemilumi- nescent, or enzymatic label, such as horseradish peroxidase, alkaline phosphatase, or luciferase.
  • binding of a test compound to a human glucose transporter polypeptide can be determined without labeling either of the interactants.
  • a micro- physiometer can be used to detect binding of a test compound with a human glucose transporter polypeptide.
  • a microphysiometer e.g., CytosensorTM
  • LAPS light-addressable potentiometric sensor
  • Determining the ability of a test compound to bind to a human glucose transporter polypeptide also can be accomplished using a technology such as real-time Bimolecular Interaction Analysis (BIA) (Sjolander & Urbaniczky, Anal. Chem. 63,
  • BIA is a technology for studying biospecific interactions in real time, without labeling any of the interactants (e.g., BIAcoreTM). Changes in the optical phenomenon surface plasmon resonance (SPR) can be used as an indication of real-time reactions between biological molecules.
  • SPR surface plasmon resonance
  • a human glucose transporter polypeptide can be used as a "bait protein" in a two-hybrid assay or three-hybrid assay (see, e.g., U.S. Patent 5,283,317; Zervos et al, Cell 72, 223-232, 1993; Madura et al, J. Biol. Chem. 268, 12046-12054, 1993; Bartel et al, BioTechmques 14, 920-924, 1993; Iwabuchi et al, Oncogene 8, 1693-1696, 1993; and Brent W094/10300), to identify other proteins which bind to or interact with the glucose transporter polypeptide and modulate its activity.
  • the two-hybrid system is based on the modular nature of most transcription factors, •which consist of separable DNA-binding and activation domains.
  • the assay utilizes two different DNA constructs.
  • polynucleotide encoding a human glucose transporter polypeptide can be fused to a polynucleotide encoding the DNA binding domain of a known transcription factor (e.g., GAL-4).
  • a DNA sequence that encodes an unidentified protein (“prey" or "sample” can be fused to a polynucleotide that codes for the activation domain of the known transcription factor.
  • the DNA-binding and activation domains of the transcription factor are brought into close proximity. This proximity allows transcription of a reporter gene (e.g., LacZ), which is operably linked to a transcriptional regulatory site responsive to the transcription factor.
  • a reporter gene e.g., LacZ
  • Expression of the reporter gene can be detected, and cell colonies containing the functional transcription factor can be isolated and used to obtain the DNA sequence encoding the protein that interacts with the glucose transporter polypeptide.
  • glucose transporter polypeptide or polynucleotide
  • test compound can be bound to a solid support.
  • suitable solid supports include, but are not limited to, glass or plastic slides, tissue culture plates, microtiter wells, tubes, silicon chips, or particles such as beads (including, but not limited to, latex, polystyrene, or glass beads).
  • any method known in the art can be used to attach the polypeptide (or polynucleotide) or test compound to a solid support, including use of covalent and non-covalent linkages, passive absorption, or pairs of binding moieties attached respectively to the polypeptide (or polynucleotide) or test compound and the solid support.
  • Test compounds are preferably bound to the solid support in an array, so that the location of individual test compounds can be tracked. Binding of a test compound to a human glucose transporter polypeptide (or polynucleotide) can be accomplished in any vessel suitable for containing the reactants. Examples of such vessels include microtiter plates, test tubes, and microcentrifuge tubes.
  • the glucose transporter polypeptide is a fusion protein comprising a domain that allows the glucose transporter polypeptide to be bound to a solid support.
  • glutathione-S-transferase fusion proteins can be adsorbed onto glutathione sepharose beads (Sigma Chemical, St. Louis, Mo.) or glutathione derivatized microtiter plates, which are then combined with the test compound or the test compound and the non-adsorbed glucose transporter polypeptide; the mixture is then incubated under conditions conducive to complex formation (e.g., at physiological conditions for salt and pH). Following incubation, the beads or microtiter plate wells are washed to remove any unbound components. Binding of the interactants can be determined either directly or indirectly, as described above. Alternatively, the complexes can be dissociated from the solid support before binding is determined.
  • a human glucose transporter polypeptide (or polynucleotide) or a test compound can be immobilized utilizing conjugation of biotin and streptavidin.
  • Biotinylated glucose transporter polypeptides (or polynucleotides) or test compounds can be prepared from biotin-NHS(N- hydroxysuccinimide) using techniques well known in the art (e.g., biotinylation kit, Pierce Chemicals, Rockford, 111.) and immobilized in the wells of streptavidin-coated 96 well plates (Pierce Chemical).
  • antibodies which specifically bind to a glucose fransporter polypeptide, polynucleotide, or a test compound, but which do not interfere with a desired binding site can be derivatized to the wells of the plate. Unbound target or protein can be trapped in the wells by antibody conjugation.
  • Methods for detecting such complexes include immunodetection of complexes using antibodies which specifically bind to the glucose transporter polypeptide or test compound, and SDS gel electrophoresis under non-reducing conditions.
  • Screening for test compounds which bind to a human glucose transporter polypeptide or polynucleotide also can be carried out in an intact cell. Any cell which comprises a glucose transporter polypeptide or polynucleotide can be used in a cell-based assay system. A glucose transporter polynucleotide can be naturally occurring in the cell or can be introduced using techniques such as those described above. Binding of the test compound to a glucose transporter polypeptide or polynucleotide is determined as described above.
  • Test compounds can be tested for the ability to increase or decrease the transporter activity of a human glucose transporter polypeptide.
  • Transporter activity can be measured, for example, as described in Cornford et al, Am J Physiol Heart Circ Physiol 2000 Sep;279(3):Hl 346-54.
  • Functional assays can be carried out after contacting either a purified glucose transporter polypeptide, a cell membrane preparation, or an intact cell with a test compound.
  • a test compound which decreases a transporter activity of a glucose transporter polypeptide by at least about 10, preferably about 50, more preferably about 75, 90, or 100% is identified as a potential therapeutic agent for decreasing glucose transporter activity.
  • a test compound which increases a transporter activity of a human glucose transporter polypeptide by at least about 10, preferably about 50, more preferably about 75, 90, or 100% is identified as a potential therapeutic agent for increasing human glucose transporter activity.
  • test compounds that increase or decrease glucose transporter gene expression are identified.
  • a glucose transporter polynucleotide is contacted with a test compound, and the expression of an RNA or polypeptide product of the glucose transporter polynucleotide is determined.
  • the level of expression of appropriate mRNA or polypeptide in the presence of the test compound is compared to " the level of expression of mRNA or polypeptide in the absence of the test compound.
  • the test compound can then be identified as a modulator of expression based on this comparison. For example, when expression of mRNA or polypeptide is greater in the presence of the test compound than in its absence, the test compound is identified as a stimulator or enhancer of the mRNA or polypeptide expression. Alternatively, when expression of the mRNA or polypeptide is less in the presence of the test compound than in its absence, the test compound is identified as an inhibitor of the mRNA or polyp eptide expression.
  • the level of glucose transporter mRNA or polypeptide expression in the cells can be determined by methods well known in the art for detecting mRNA or polypeptide. Either qualitative or quantitative methods can be used.
  • the presence of polypeptide products of a human glucose transporter polynucleotide can be determined, for example, using a variety of techniques known in the art, including immunochemical methods such as radioimmunoassay, Western blotting, and immunohistochemistry.
  • polypeptide synthesis can be determined in vivo, in a cell culture, or in an in vitro translation system by detecting incorporation of labeled amino acids into a human glucose transporter polypeptide.
  • Such screening can be carried out either in a cell-free assay system or in an intact cell.
  • Any cell that expresses a human glucose transporter polynucleotide can be used in a cell-based assay system.
  • the glucose transporter polynucleotide can be naturally occurring in the cell or can be introduced using techniques such as those described above.
  • Either a primary culture or an established cell line, such as CHO or human embryonic kidney 293 cells, can be used.
  • compositions of the invention can comprise, for example, a human glucose transporter polypeptide, glucose transporter polynucleotide, ribozymes or antisense oligonucleotides, antibodies which specifically bind to a glucose transporter polypeptide, or mimetics, activators, or inhibitors of a human glucose transporter polypeptide activity.
  • the compositions can be administered alone or in combination with at least one other agent, such as stabilizing compound, which can be administered in any sterile, biocompatible pharmaceutical carrier, including, but not limited to, sahne, buffered saline, dextrose, and water.
  • the compositions can be admimstered to a patient alone, or in combination with other agents, drugs or hormones.
  • compositions of the invention can be administered by any number of routes including, but not limited to, oral, intravenous, intramuscular, infra-arterial, intramedullary, intrathecal, intraventricular, transdermal, subcutaneous, intraperitoneal, intranasal, parenteral, topical, sublingual, or rectal means.
  • Pharmaceutical compositions for oral administration can be formulated using pharmaceutically acceptable carriers well known in the art in dosages suitable for oral administration. Such carriers enable the pharmaceutical compositions to be formulated as tablets, pills, dragees, capsules, liquids, gels, syrups, slurries, suspensions, and the like, for ingestion by the patient.
  • compositions for oral use can be obtained through combination of active compounds with solid excipient, optionally grinding a resulting mixture, and processing the " mixture of granules, after adding suitable auxiliaries, if desired, to obtain tablets or dragee cores.
  • Suitable excipients are carbohydrate or protein fillers, such as sugars, including lactose, sucrose, mannitol, or sorbitol; starch from corn, wheat, rice, potato, or other plants; cellulose, such as methyl cellulose, hydroxypropylmethyl-cellulose, or sodium carboxymethylcellulose; gums including arabic and fragacanth; and proteins such as gelatin and collagen.
  • disintegrating or solubilizing agents can be added, such as the cross-linked polyvinyl pyrrolidone, agar, alginic acid, or a salt thereof, such as sodium alginate.
  • Dragee cores can be used in conjunction with suitable coatings, such as concentrated sugar solutions, which also can contain gum arabic, talc, polyvinylpyrrolidone, carbopol gel, polyethylene glycol, and or titanium dioxide, lacquer solutions, and suitable organic solvents or solvent mixtures.
  • suitable coatings such as concentrated sugar solutions, which also can contain gum arabic, talc, polyvinylpyrrolidone, carbopol gel, polyethylene glycol, and or titanium dioxide, lacquer solutions, and suitable organic solvents or solvent mixtures.
  • Dyestuffs or pigments can be added to the tablets or dragee coatings for product identification or to characterize the quantity of active compound, i.e., dosage.
  • compositions that can be used orally include push-fit capsules made of gelatin, as well as soft, sealed capsules made of gelatin and a coating, such as glycerol or sorbitol.
  • Push-fit capsules can contain active ingredients mixed with a filler or binders, such as lactose or starches, lubricants, such as talc or magnesium stearate, and, optionally, stabilizers.
  • the active compounds can be dissolved or suspended in suitable liquids, such as fatty oils, liquid, or liquid polyethylene glycol with or without stabilizers.
  • compositions suitable for parenteral administration can be formulated in aqueous solutions, preferably in physiologically compatible buffers such as
  • Aqueous injection suspensions can contain substances that increase the viscosity of the suspension, such as sodium carboxymethyl cellulose, sorbitol, or dextran. Additionally, suspensions of the active compounds can be prepared as appropriate oily injection suspensions. Suitable lipophilic solvents or vehicles include fatty oils such as sesame oil, or synthetic fatty acid esters, such as ethyl oleate or triglycerides, or liposomes. Non-lipid polycationic amino polymers also can be used for delivery. Optionally, the suspension also can contain suitable stabilizers or agents that increase the solubility of the compounds to allow for the preparation of highly concentrated solutions. For topical or nasal administration, penevers appropriate to the particular barrier to be permeated are used in the formulation. Such peneflops are generally known in the art.
  • compositions of the present invention can be manufactured in a manner that is known in the art, e.g., by means of conventional mixing, dissolving, granulating, dragee-making, levigating, emulsifying, encapsulating, entrapping, or lyophilizing processes.
  • the pharmaceutical composition can be provided as a salt and can be formed with many acids, including but not limited to, hydrochloric, sulfuric, acetic, lactic, tartaric, malic, succinic, etc. Salts tend to be more soluble in aqueous or other protonic solvents than are the corresponding free base forms.
  • the preferred preparation can be a lyophilized powder which can contain any or all of the following: 1-50 mM histidine, 0.1%-2%o sucrose, and 2-7% mannitol, at a pH range of 4.5 to 5.5, that is combined with buffer prior to use.
  • compositions After pharmaceutical compositions have been prepared, they can be placed in an appropriate container and labeled for freatment of an indicated condition. Such labeling would include amount, frequency, and method of administration.
  • Human glucose transporter can be regulated to treat diabetes.
  • Diabetes mellitus is a common metabolic disorder characterized by an abnormal elevation in blood glucose, alterations in lipids and abnormalities (complications) in the cardiovascular system, eye, kidney and nervous system. Diabetes is divided into two separate diseases: type 1 diabetes (juvenile onset), which results from a loss of cells which make and secrete insulin, and type 2 diabetes (adult onset), which is caused by a defect in insulin secretion and a defect in insuUn action.
  • type 1 diabetes juvenile onset
  • type 2 diabetes adult onset
  • Type 1 diabetes is initiated by an autoimmune reaction that attacks the insulin secreting cells (beta cells) in the pancreatic islets.
  • Agents that prevent this reaction from occurring or that stop the reaction before destruction of the beta cells has been accomplished are potential therapies for this disease.
  • Other agents that induce beta cell proliferation and regeneration also are potential therapies.
  • Type II diabetes is the most common of the two diabetic conditions (6% of the population).
  • the defect in insulin secretion is an important cause of the diabetic condition and results from an inability of the beta cell to properly detect and respond to rises in blood glucose levels with insulin release.
  • Therapies that increase the response by the beta cell to glucose would offer an important new treatment for this disease.
  • the defect in insulin action in Type II diabetic subjects is another target for therapeutic intervention.
  • Agents that increase the activity of the insulin receptor in muscle, liver, and fat will cause a decrease in blood glucose and a normalization of plasma lipids.
  • the receptor activity can be increased by agents that directly stimulate the receptor or that increase the intracellular signals from the receptor.
  • Other therapies can directly activate the cellular end process, i.e. glucose transport or various enzyme systems, to generate an insulin-like effect and therefore a produce beneficial outcome. Because overweight subjects have a greater susceptibility to Type II diabetes, any agent that reduces body weight is a possible therapy.
  • Type I and Type diabetes can be treated with agents that mimic insulin action or that treat diabetic complications by reducing blood glucose levels.
  • agents that reduces new blood vessel growth can be used to treat the eye complications that develop in both diseases.
  • This invention further pertains to the use of novel agents identified by the screening assays described above. Accordingly, it is within the scope of this invention to use a test compound identified as described herein in an appropriate animal model.
  • an agent identified as described herein e.g., a modulating agent, an antisense nucleic acid molecule, a specific antibody, ribozyme, or a human glucose transporter polypeptide binding molecule
  • an agent identified as described herein can be used in an animal model to determine the efficacy, toxicity, or side effects of treatment with such an agent.
  • an agent identified as described herein can be used in an animal model to determine the mechanism of action of such an agent.
  • this invention pertains to uses of novel agents identified by the above-described screening assays for treatments as described herein.
  • a reagent which affects glucose transporter activity can be administered to a human cell, either in vitro or in vivo, to reduce glucose fransporter activity.
  • the reagent preferably binds to an expression product of a human glucose transporter gene. If the expression product is a protein, the reagent is preferably an antibody.
  • an antibody can be added to a preparation of stem cells that have been removed from the body. The cells can then be replaced in the same or another human body, with or without clonal propagation, as is known in the art.
  • the reagent is delivered using a liposome.
  • the liposome is stable in the animal into which it has been administered for at least about
  • a liposome comprises a lipid composition that is capable of targeting a reagent, particularly a polynucleotide, to a particular site in an animal, such as a human.
  • the lipid composition of the liposome is capable of targeting to a specific organ of an animal, such as the lung, liver, spleen, heart brain, lymph nodes, and skin.
  • a liposome useful in the present invention comprises a lipid composition that is capable of fusing with the plasma membrane of the targeted cell to deliver its contents to the cell.
  • the transfection efficiency of a liposome is about
  • a liposome is between about 100 and 500 nm, more preferably between about 150 and 450 nm, and even more preferably between about 200 and 400 nm in diameter.
  • Suitable liposomes for use in the present invention include those liposomes standardly used in, for example, gene delivery methods known to those of skill in the art. More preferred liposomes include liposomes having a polycationic lipid composition and or liposomes having a cholesterol backbone conjugated to polyethylene glycol.
  • a liposome comprises a compound capable of targeting the liposome to a particular cell type, such as a cell-specific ligand exposed on the outer surface of the liposome.
  • Complexing a liposome with a reagent such as an antisense oligonucleotide or ribozyme can be achieved using methods that are standard in the art (see, for example, U.S. Patent 5,705,151).
  • polynucleotide is combined with about 8 nmol of liposomes, more preferably from about 0.5 ⁇ g to about 5 ⁇ g of polynucleotides are combined with about 8 nmol liposomes, and even more preferably about 1.0 ⁇ g of polynucleotides is combined with about 8 nmol liposomes.
  • antibodies can be delivered to specific tissues in vivo using receptor-mediated targeted delivery.
  • Receptor-mediated DNA delivery techniques are taught in, for example, Findeis et al. Trends in Biotechnol. 11, 202-05 (1993);
  • a therapeutically effective dose refers to that amount of active ingredient which increases or decreases enzymatic activity relative to the enzymatic activity which occurs in the absence of the therapeutically effective dose.
  • the therapeutically effective dose can be estimated initially either in cell culture assays or in animal models, usually mice, rabbits, dogs, or pigs.
  • the animal model also can be used to determine the appropriate concentration range and route of administration. Such information can then be used to determine useful doses and routes for administration in humans.
  • Therapeutic efficacy and toxicity e.g., ED 50 (the dose therapeutically effective in
  • LD 50 the dose lethal to 50% of the population
  • the dose ratio of toxic to therapeutic effects is the therapeutic index, and it can be expressed as the ratio, LD S Q/ED SO .
  • compositions that exhibit large therapeutic indices are preferred.
  • the data obtained from cell culture assays and animal studies is used in formulating a range of dosage for human use.
  • the dosage contained in such compositions is preferably within a range of circulating concentrations that include the ED 50 with little or no toxicity.
  • the dosage varies within this range depending upon the dosage form employed, sensitivity of the patient, and the route of administration.
  • the exact dosage will be determined by the practitioner, in light of factors related to the subject that requires treatment. Dosage and administration are adjusted to provide sufficient levels of the active ingredient or to maintain the desired effect. Factors that can be taken into account include the severity of the disease state, general health of the subject, age, weight, and gender of the subject, diet, time and frequency of administration, drug combination(s), reaction sensitivities, and tolerance/response to therapy. Long-acting pharmaceutical compositions can be administered every 3 to 4 days, every week, or perennial every two weeks depending on the half-life and clearance rate of the particular formulation.
  • Normal dosage amounts can vary from 0.1 to 100,000 micrograms, up to a total dose of about 1 g, depending upon the route of administration.
  • Guidance as to particular dosages and methods of delivery is provided in the literature and generally available to practitioners in the art. Those skilled in the art will employ different formulations for nucleotides than for proteins or their inhibitors. Similarly, delivery of polynucleotides or polypeptides will be specific to particular cells, conditions, locations, etc.
  • polynucleotides encoding the antibody can be constructed and introduced into a cell either ex vivo or in vivo using well- established techniques including, but not limited to, transferrin-polycation-mediated DNA transfer, transfection with naked or encapsulated nucleic acids, liposome- mediated cellular fusion, intracellular transportation of DNA-coated latex beads, protoplast fusion, viral infection, elecfroporation, "gene gun,” and DEAE- or calcium phosphate-mediated transfection.
  • Effective in vivo dosages of an antibody are in the range of about 5 ⁇ g to about 50 ⁇ g/kg, about 50 ⁇ g to about 5 mg/kg, about 100 ⁇ g to about 500 ⁇ g/kg of patient body weight, and about 200 to about 250 ⁇ g/kg of patient body weight.
  • effective in vivo dosages are in the range of about 100 ng to about 200 ng, 500 ng to about 50 mg, about 1 ⁇ g to about 2 mg, about 5 ⁇ g to about 500 ⁇ g, and about 20 ⁇ g to about 100 ⁇ g of DNA.
  • the reagent is preferably an antisense oligonucleotide or a ribozyme.
  • Polynucleotides that express antisense oligonucleotides or ribozymes can be introduced into cells by a variety of methods, as described above.
  • a reagent reduces expression of a human glucose transporter gene or the activity of a glucose transporter polypeptide by at least about 10, preferably about 50, more preferably about 75, 90, or 100% relative to the absence of the reagent.
  • the effectiveness of the mechanism chosen to decrease the level of expression of a human glucose transporter gene or the activity of a human glucose transporter polypeptide can be assessed using methods well known in the art, such as hybridization of nucleotide probes to glucose transporter-specific mRNA, quantitative RT-PCR, immunologic detection of a human glucose transporter polypeptide, or measurement of enzymatic activity.
  • any of the pharmaceutical compositions of the invention can be administered in combination with other appropriate therapeutic agents.
  • Selection of the appropriate agents for use in combination therapy can be made by one of ordinary skill in the art, according to conventional pharmaceutical principles.
  • the combination of therapeutic agents can act syner- gistically to effect the treatment or prevention of the various disorders described above. Using this approach, one may be able to achieve therapeutic efficacy with lower dosages of each agent, thus reducing the potential for adverse side effects.
  • any of the therapeutic methods described above can be applied to any subject in need of such therapy, including, for example, mammals such as dogs, cats, cows, horses, rabbits, monkeys, and most preferably, humans.
  • Human glucose transporter also can be used in diagnostic assays for detecting diseases and abnormalities or susceptibility to diseases and abnormalities related to the presence of mutations in the nucleic acid sequences that encode the transporter.
  • differences can be determined between the cDNA or genomic sequence encoding glucose transporter in individuals afflicted with a disease and in normal individuals. If a mutation is observed in some or all of the afflicted individuals but not in normal individuals, then the mutation is likely to be the causative agent of the disease.
  • Sequence differences between a reference gene and a gene having mutations can be revealed by the direct DNA sequencing method.
  • cloned DNA segments can be employed as probes to detect specific DNA segments.
  • the sensitivity of this method is greatly enhanced when combined with PCR.
  • a sequencing primer can be used with a double-stranded PCR product or a single-stranded template molecule generated by a modified PCR.
  • the sequence determination is performed by conventional procedures using radiolabeled nucleotides or by automatic sequencing procedures using fluorescent tags. Genetic testing based on DNA sequence differences can be carried out by detection of alteration in electrophoretic mobility of DNA fragments in gels with or without denaturing agents. Small sequence deletions and insertions can be visualized, for example, by high resolution gel electrophoresis.
  • DNA fragments of different sequences can be distinguished on denaturing formamide gradient gels in which the mobilities of different DNA fragments are retarded in the gel at different positions according to their specific melting or partial melting temperatures (see, e.g., Myers et al, Science 230, 1242, 1985). Sequence changes at specific locations can also be revealed by nuclease protection assays, such as RNase and S 1 protection or the chemical cleavage method (e.g., Cotton et al, Proc. Natl. Acad. Sci. USA 85,
  • the detection of a specific DNA sequence can be performed by methods such as hybridization, RNase protection, chemical cleavage, direct DNA sequencing or the use of restriction enzymes and Southern blotting of genomic DNA.
  • direct methods such as gel-electrophoresis and DNA sequencing, mutations can also be detected by in situ analysis.
  • Altered levels of glucose fransporter also can be detected in various tissues.
  • Assays used to detect levels of the receptor polypeptides in a body sample, such as blood or a tissue biopsy, derived from a host are well known to those of skill in the art and include radioimmunoassays, competitive binding assays, Western blot analysis, and
  • the polynucleotide of SEQ ID NO: 1 is inserted into the expression vector pCEV4 and the expression vector pCEV4-glucose transporter polypeptide obtained is transfected into human embryonic kidney 293 cells.
  • the cells are cultured on 6-well plates. Transport is initiated by washing the cells twice in a transport solution (20 mM Hepes, 137 mM NaCl, 4.7 mM KC1, 1.2 mM MgSO4, 1.2 mM KH2PO4, 2.5 mM CaC12, 2 mM pyruvate,m pH 7.4).
  • Cells are then incubated for 10 min with a transport solution that contained 0.1 mM 2-deoxy-D-glucose and 1 ⁇ Ci of 2-deoxy- D-[3H]glucose uptake (10 mCi/mmol).
  • a transport solution that contained 0.1 mM 2-deoxy-D-glucose and 1 ⁇ Ci of 2-deoxy- D-[3H]glucose uptake (10 mCi/mmol).
  • PBS phosphate-buffered saline buffer
  • the Pichia pastoris expression vector pPICZB (Invitrogen, San Diego, CA) is used to produce large quantities of recombinant human glucose transporter polypeptides in yeast.
  • the glucose transporter-encoding DNA sequence is derived from SEQ ID NO: 1. Before insertion into vector pPICZB, the DNA sequence is modified by well known methods in such a way that it contains at its 5 '-end an initiation codon and at its 3 '-end an enterokinase cleavage site, a His6 reporter tag and a termination codon.
  • the yeast is cultivated under usual conditions in 5 liter shake flasks and the recombinantly produced protein isolated from the culture by affinity chromatography (Ni-NTA-Resin) in the presence of 8 M urea.
  • the bound polypeptide is eluted with buffer, pH 3.5, and neutralized. Separation of the polypeptide from the His6 reporter tag is accomplished by site-specific proteolysis using enterokinase (Invitrogen, San Diego, CA) according to manufacturer's instructions. Purified human glucose transporter polypeptide is obtained.
  • Purified glucose transporter polypeptides comprising a glutathione-S-transferase protein and absorbed onto glutathione-derivatized wells of 96-well microtiter plates are contacted with test compounds from a small molecule library at pH 7.0 in a physiological buffer solution.
  • Human glucose transporter polypeptides comprise the amino acid sequence shown in SEQ ID NO: 2.
  • the test compounds comprise a fluorescent tag. The samples are incubated for 5 minutes to one hour. Control samples are incubated in the absence of a test compound.
  • the buffer solution containing the test compounds is washed from the wells.
  • Binding of a test compound to a human glucose transporter polypeptide is detected by fluorescence measurements of the contents of the wells.
  • a test compound that increases the fluorescence in a well by at least 15% relative to fluorescence of a well in which a test compound is not incubated is identified as a compound which binds to a human glucose transporter polypeptide.
  • test compound is administered to a culture of human cells transfected with a glucose transporter expression construct and incubated at 37°C for 10 to 45 rninutes.
  • a culture of the same type of cells that have not been transfected is incubated for the same time without the test compound to provide a negative control.
  • RNA is isolated from the two cultures as described in Chirgwin et al, Biochem. 18, 5294-99, 1979).
  • Northern blots are prepared using 20 to 30 ⁇ g total RNA and hybridized with a 32 P-labeled glucose transporter-specific probe at 65°C in Express- hyb (CLONTECH).
  • the probe comprises at least 11 contiguous nucleotides selected from the complement of SEQ ID NO: 1.
  • a test compound that decreases the glucose transporter-specific signal relative to the signal obtained in the absence of the test compound is identified as an inhibitor of glucose transporter gene expression.
  • test compound is administered to a culture of human cells transfected with a sugar transporter expression construct and incubated at 37°C for 10 to 45 minutes.
  • a culture of the same type of cells which have not been transfected is incubated for the same time without the test compound to provide a negative control.
  • Transporter activity is measured using the method of Cornford et al, Ami Physiol Heart Circ
  • a test compound which decreases the transporter activity of the sugar transporter relative to the transporter activity in the absence of the test compound is identified as an inhibitor of sugar transporter activity.
  • RT-PCR Reverse Transcription-Polymerase Chain Reaction
  • glucose transporter is involved in the disease process of diabetes
  • the following whole body panel is screened to show predominant or relatively high expression: subcutaneous and mesenteric adipose tissue, adrenal gland, bone marrow, brain, colon, fetal brain, heart, hypothalamus, kidney, liver, lung, mammary gland, pancreas, placenta, prostate, salivary gland, skeletal muscle, small intestine, spleen, stomach, testis, thymus, thyroid, trachea, and uterus.
  • Human islet cells and an islet cell library also are tested.
  • the expression of glucose transporter in cells derived from normal individuals with the expression of cells derived from diabetic individuals is compared.
  • Quantitative expression profiling is performed by the form of quantitative PCR analysis called "kinetic analysis” firstly described in Higuchi et al, BioTechnology
  • the probe is cleaved by the 5 '-3' endonuclease activity of Taq DNA polymerase and a fluorescent dye released in the medium (Holland et al, Proc. Natl. Acad. Sci. U.S.A. 88, 7276-80, 1991). Because the fluorescence emission will increase in direct proportion to the amount of the specific amplified product, the exponential growth phase of PCR product can be detected and used to determine the initial template concentration (Heid et al, Genome Res. 6, 986-94, 1996, and Gibson et al, Genome Res. 6, 995-1001, 1996).
  • the amplification of an endogenous control can be performed to standardize the amount of sample RNA added to a reaction.
  • the control of choice is the 18S ribosomal RNA. Because reporter dyes with differing emission spectra are available, the target and the endogenous control can be independently quantified in the same tube if probes labeled with different dyes are used.
  • RNA extraction and cDNA preparation Total RNA from the tissues listed above are used for expression quantification. RNAs labeled "from autopsy” were extracted from autoptic tissues with the TRIzol reagent (Life Technologies, MD) according to the manufacturer's protocol.
  • RNA Fifty ⁇ g of each RNA were treated with DNase I for 1 hour at 37°C in the following reaction mix: 0.2 U/ ⁇ l RNase-free DNase I (Roche Diagnostics, Germany); 0.4 U/ ⁇ l RNase inhibitor (PE Applied Biosystems, CA); 10 mM Tris-HCI pH 7.9; lO mM MgCl 2 ; 50 mM NaCl; and 1 mM DTT.
  • RNA is extracted once with 1 volume of pheno chloroform:- isoamyl alcohol (24:24:1) and once with chloroform, and precipitated with 1/10 volume of 3 M sodium acetate, pH5.2, and 2 volumes of ethanol.
  • Fifty ⁇ g of each RNA from the autoptic tissues are DNase treated with the DNA-free kit purchased from Ambion (Ambion, TX). After resuspension and spectro- photometric quantification, each sample is reverse transcribed with the TaqMan Reverse Transcription Reagents (PE Applied Biosystems, CA) according to the manufacturer's protocol. The final concentration of RNA in the reaction mix is
  • Reverse transcription is carried out with 2.5 ⁇ M of random hexamer primers.
  • TaqMan quantitative analysis Specific primers and probe are designed according to the recommendations of PE Applied Biosystems; the probe can be labeled at the 5' end FAM (6-carboxy-fluorescein) and at the 3' end with TAMRA (6-carboxy- tetramethyl-rhodamine). Quantification experiments are performed on 10 ng of reverse transcribed RNA from each sample. Each determination is done in triplicate.
  • FAM 6-carboxy-fluorescein
  • TAMRA 6-carboxy- tetramethyl-rhodamine
  • the assay reaction mix is as follows: IX final TaqMan Universal PCR Master Mix (from 2X stock) (PE Applied Biosystems, CA); IX PDAR control - 18S RNA (from 2X stock) (PE Applied Biosystems, CA); IX PDAR control - 18S RNA (from 2X stock) (PE Applied Biosystems, CA); IX PDAR control - 18S RNA (from 2X stock) (PE Applied Biosystems, CA); IX PDAR control - 18S RNA (from
  • Overnight fasted normal rats or mice have elevated rates of gluconeogenesis as do streptozotocin-induced diabetic rats or mice fed ad libitum.
  • Rats are made diabetic with a single intravenous injection of 40 mg/kg of streptozotocin while C57BL/KsJ mice are given 40- 60 mg/kg i.p. for 5 consecutive days.
  • Blood glucose is measured from tail-tip blood and then compounds are administered via different routes (p.o., i.p., i.v., s.c). Blood is collected at various times thereafter and glucose measured. Alternatively, compounds are administered for several days, then the animals are fasted overnight, blood is collected and plasma glucose measured. Compounds that inhibit glucose production will decrease plasma glucose levels compared to the vehicle-treated control group.
  • Both ob/ob and db/db mice as well as diabetic Zucker rats are hyperglycemic, hyperinsulinemic and insulin resistant.
  • the animals are pre-bled, their glucose levels measured, and then they are grouped so that the mean glucose level is the same for each group.
  • Compounds are administered daily either q.d. or b.i.d. by different routes (p.o., i.p., s.c.) for 7-28 days. Blood is collected at various times and plasma glucose and insulin levels determined. Compounds that improve insulin sensitivity in these models will decrease both plasma glucose and insulin levels when compared to the vehicle-treated control group.
  • Compounds that enhance insulin secretion from the pancreas will increase plasma insulin levels and improve the disappearance of plasma glucose following the administration of a glucose load.
  • compounds are administered by different routes (p.o., i.p., s.c. or i.v.) to overnight fasted normal rats or mice.
  • an intravenous glucose load (0.4 g/kg) is given, blood is collected one minute later.
  • Plasma insulin levels are determined.
  • Compounds that enhance insulin secretion will increase plasma insulin levels compared to animals given only glucose.
  • animals are bled at the appropriate time after compound administration, then given either an oral or intraperitoneal glucose load (lg/kg), bled again after 15, 30, 60 and
  • test compounds which regulate glucose transporter are administered by different. routes (p.o., i.p., s.c, or i.v.) to overnight fasted normal rats or mice. At the appropriate time an intravenous glucose load (0.4 g/kg) is given, blood is collected one minute later.
  • Plasma insulin levels are determined. Test compounds that enhance insulin secretion will increase plasma insulin levels compared to animals given only glucose. When measuring glucose disappearance, animals are bled at the appropriate time after compound administration, then given either an oral or intraperitoneal glucose load (1 g kg), bled again after 15, 30, 60, and 90 minutes and plasma glucose levels determined. Test compounds that increase insulin levels will decrease glucose levels and the area-under-the glucose curve when compared to the vehicle-treated group given only glucose.
  • Blood glucose is measured from tail-tip blood and then compounds are administered via different routes (p.o., i.p., i.v., s.c). Blood is collected at various times thereafter and glucose measured. Alternatively, compounds are administered for several days, then the animals are fasted overnight, blood is collected and plasma glucose measured. Compounds that inhibit glucose production will decrease plasma glucose levels compared to the vehicle-treated control group.
  • Both ob/ob and db/db mice as well as diabetic Zucker rats are hyperglycemic, hyperinsulinemic and insulin resistant.
  • the animals are pre-bled, their glucose levels measured, and then they are grouped so that the mean glucose level is the same for each group.
  • Compounds are administered daily either q.d. or b.i.d. by different routes (p.o., i.p., s.c.) for 7-28 days. Blood is collected at various times and plasma glucose and insulin levels determined. Compounds that improve insulin sensitivity in these models will decrease both plasma glucose and insulin levels when compared to the vehicle-treated control group.
  • Compounds that enhance insulin secretion from the pancreas will increase plasma insulin levels and improve the disappearance of plasma glucose following the administration of a glucose load.
  • compounds are administered by different routes (p.o., i.p., s.c. or i.v.) to overnight fasted normal rats or mice.
  • an intravenous glucose load (0.4 g/kg) is given, blood is collected one minute later.
  • Plasma insulin levels are determined.
  • Compounds that enhance insulin secretion will increase plasma insulin levels compared to animals given only glucose.
  • animals are bled at the appropriate time after compound administration, then given either an oral or intraperitoneal glucose load (1 g/kg), bled again after 15, 30, 60 and 90 minutes and plasma glucose levels determined.
  • Compounds that increase insulin levels will decrease glucose levels and the area-under-the glucose curve when compared to the vehicle-treated group given only glucose.

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Abstract

Les réactifs régulant le transporteur de glucose humain et les réactifs se liant aux produits géniques du transporteur de glucose peuvent jouer un rôle dans la prévention, l'amélioration ou la correction de dysfonctionnements ou de maladies dont, entre autres, le diabète.
PCT/EP2002/012058 2001-10-30 2002-10-29 Regulation du transporteur de glucose humain WO2003038094A1 (fr)

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Publication number Priority date Publication date Assignee Title
US5942398A (en) * 1998-02-26 1999-08-24 Millennium Pharmaceuticals, Inc. Nucleic acid molecules encoding glutx and uses thereof
WO2002004520A2 (fr) * 2000-07-07 2002-01-17 Incyte Genomics, Inc. Transporteurs et canaux ioniques
WO2002046406A2 (fr) * 2000-12-04 2002-06-13 Pe Corporation (Ny) Proteines transporteurs humaines isolees, molecules d'acides nucleiques codant ces proteines, et utilisations correspondantes
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