WO2000027861A1

WO2000027861A1 - Novel phosphodiesterase interacting proteins

Info

Publication number: WO2000027861A1
Application number: PCT/US1999/026860
Authority: WO
Inventors: Marco Conti; Gudrun Pahlke
Original assignee: The Board Of Trustees Of The Leland Stanford Junior University
Priority date: 1998-11-12
Filing date: 1999-11-12
Publication date: 2000-05-18
Also published as: AU1621400A

Abstract

Nucleic acid compositions encoding novel PDE interacting proteins, as well as the novel PDE interacting proteins themselves, are provided. Also provided are methods of producing the subject nucleic acid and protein compositions. The subject polypeptide and nucleic acid compositions find use in a variety of applications, including research, diagnostic, and therapeutic agent screening applications, as well as in treatment therapies for disease conditions associated with PDE activity, particularly inflammatory diseases.

Description

NOVEL PHOSPHODIESTERASE INTERACTING PROTEINS

ACKNOWLEDGMENT OF GOVERNMENT SUPPORT

This invention was made with Government support under Grant No. HD20788 awarded by the National Institutes of Health. The Government has certain rights in this invention.

INTRODUCTION

Field of the Invention

The field of the invention is cyclic nucleotide phosphodiesterases, particularly cAMP phosphodiesterases. Background of the Invention Cyclic nucleotide phosphodiesterases are a class of enzymes that catalyze the hydrolysis of phosphodiester bonds in cyclic nucleotides, e.g. cAMP. Cyclic nucleotides are important second messengers that regulate and mediate a number of cellular responses to extracellular signals, such as hormones, light and neurotransmitters. Since cyclic nucleotide phosphodiesterases modulate the concentration of cyclic nucleotides, these enzymes play a significant role in signal transduction. There are at least ten different classes of cyclic phosphodiesterases, seven of which are: (I) Ca(2+)/calmodulin-dependent PDEs; (II) cGMP- stimulated PDEs; (III) cGMP-inhibited PDEs; (IV) cAMP-specific PDEs; (V) cGMP-specific PDEs; (VI) photoreceptor PDEs; and (VII) high-affinity, cAMP-specific PDEs. Because of their role in signal transduction, cyclic nucleotide phosphodiesterases have been pursued as therapeutic or pharmacologic targets in the modulation of a variety of distinct physiological processes. cAMP phosphodiesterase inhibitors hold great promise as therapeutic agents for use in the treatment of inflammation. Specifically, data indicates that these types of inhibitors are as effective, or even more effective, than adrenal steroids in suppressing most functions of inflammatory cells, including: migration, adhesion and secretion of cytokines. Specific cAMP phosphodiesterase inhibitors that have been studied include: rolipram, theophylline, and the like. In addition, research is ongoing to identify new cAMP phosphodiesterase inhibitors. Despite their promise as anti-inflammatory therapeutic agents, cAMP- phosphodiesterase inhibitors identified to date have demonstrated significant toxic side effects that have limited to their generalized use in the treatment of inflammation.

As such, there is continued interest in the identification of new, more selective cAMP phosphodiesterase inhibitors for potential use as anti-inflammatory therapeutic agents. These efforts have employed recombinant phosphodiesterases for automated screening of candidate agents. Use of recombinant phosphodiesterases in screening applications has, however, been problematic as such recombinant enzymes have altered conformation as compared to their naturally occurring counterparts, which affects the interaction with potential inhibitors and thereby confounds the results that are obtained. As such, the screening results obtained by using such recombinant proteins are problematic.

Therefore, there is much interest in the further elucidation of the conformation of phosphodiesterases and other factors that may modulate the interaction of these enzymes with inhibitors. Relevant Literature

The role of cAMP phosphodiesterases in inflammatory processes is reviewed in Torphy, Am. J. Respir. Crit. Care Med. (1998) 157:351-370. See also Houslay et al., Adv. Pharmacol (1998) 44: 225-342 and Spina et al., Adv. Pharmacol (1998) 44: 33-89, as well as U.S. Patent No. 5,798,373, the disclosure of which is herein incorporated by reference.

SUMMARY OF THE INVENTION Nucleic acid compositions encoding phosphodiesterase interacting proteins, e.g. myomegalin, as well as the polypeptide compositions encoded thereby, are provided. Also provided are complexes of the subject phosphodiesterase interacting protein with a phosphodiesterase enzyme. The subject polypeptide and nucleic acid compositions, as well as complexes thereof, find use in a variety of applications, including research, diagnostic, and therapeutic agent identification and screening applications, as well as in therapeutic applications.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 provides the amino acid sequence of rat myomegalin. Figure 2 provides the cDNA sequence of a clone having an open reading frame encoding the myomegalin protein having the amino acid sequence of Figure 1.

Figure 3 provides the nucleic acid sequence from the first met to the first stop codon in the sequence of Figure 2. Figure 4 provides the nucleic acid sequence of human myomegalin.

Figure 5 provides the amino acid sequence of human myomegalin.

Figure 6 provides the amino acid sequence of rat M14 protein.

DETAILED DESCRIPTION OF THE INVENTION Novel phosphodiesterase interacting proteins, particularly myomegalin, as well as nucleic acid compositions encoding the same, are provided. Also provided are complexes of the subject proteins and phosphodiesterases. The subject polypeptide and nucleic acid compositions find use in a variety of applications, including research, diagnostic, and therapeutic agent identification and screening applications, as well as in therapeutic applications.

Before the subject invention is described further, it is to be understood that the invention is not hmited to the particular embodiments of the invention described below, as variations of the particular embodiments may be made and still fall within the scope of the appended claims. It is also to be understood that the terminology employed is for the purpose of describing particular embodiments, and is not intended to be hmiting. Instead, the scope of the present invention will be established by the appended claims.

In this specification and the appended claims, the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs.

NUCLEIC ACID COMPOSITIONS Nucleic acid compositions encoding phosphodiesterase (PDE) interacting proteins, as well as fragments thereof, are provided. The subject nucleic acid compositions encode proteins that interact with a phoshodiesterase enzyme, modulate its conformation and direct its location in a cell. In other words, the proteins encoded by the subject nucleic acid compositions are those that target a (PDE) to a particular subcellular compartment and alter the function and/or properties of the PDE. Of particular interest are nucleic acid compositions which encode proteins that bind to a PDE IV isoenzyme, including PDE4A, PDE4B, PDE4C, PDE4D, and the like.

By nucleic acid composition is meant a composition comprising a sequence of DNA having an open reading frame that encodes a PDE interacting polypeptide, i.e. a gene encoding a polypeptide that interacts with a PDE (e.g. binds to and targets a PDE), and is capable, under appropriate conditions, of being expressed as a PDE interacting polypeptide. Also encompassed in this term are nucleic acids that are homologous, substantially similar or identical to the nucleic acids encoding PDE interacting polypeptides or proteins. Thus, the subject invention provides genes encoding mammalian PDE interacting proteins, such as genes encoding human PDE interacting polypeptides and homologs thereof, as well as non- human mammalian PDE interacting polypeptides and homologs thereof, e.g. rat and mouse proteins.

Of particular interest is a nucleic acid composition encoding a myomegalin protein, particularly a mammalian myomegalin protein, described in greater detail infra, or a fragment or homolog thereof. Specific nucleic acid compositions of interest include: polynucleotides encoding a rat myomegalin protein, such as polynucleotides having a nucleotide sequence found in SEQ ID NOs: 1 or 3, including polynucleotides in which the entire sequence is the same as the sequence of SEQ ID NOs. 1 or 3; and polynucleotides encoding human myomegalin protein, such as polynucleotides having a nucleotide sequence found in SEQ ID NO: 04, including polynucleotides in which the entire sequence is the same as the sequence of SEQ ID NOs. 04, as well as those in which the entire sequence is the same as the sequence of an ORF found in SEQ LD NO:04.

Also of interest are nucleic acid compositions encoding an M14 polypeptide, described in greater detail infra, or a fragment or homolog thereof. Specific nucleic acid compositions of interest include polynucleotides encoding a rat M14 polypeptide, such as polynucleotides encoding an Ml 4 polypeptide having the amino acid sequence set forth in SEQ ID NO:08. Polynucleotides encoding M14 homologs, and polynucleotides encoding PDE-interacting fragments of an M14 polypeptide, are also of interest. Also of interest are nucleic acid compositions encoding a huntingtin-interacting protein, e.g., HLP1. Specific nucleic acid compositions of interest include a polynucleotide encoding a human HLP1 polypeptide, including, for example, a polynucleotide as disclosed in GenBank Accession No. U79734. The source of homologous genes to those specifically listed above may be any mammalian species, e.g., primate species, particularly human; rodents, such as guinea pigs and mice, canines, felines, bovines, ovines, equines, yeast, nematodes, etc. Between mammalian species, e.g., human and mouse, homologs have substantial sequence similarity, e.g. at least 75% sequence identity, usually at least 90%, more usually at least 95% between nucleotide sequences. Sequence similarity is calculated based on a reference sequence, which may be a subset of a larger sequence, such as a conserved motif, coding region, flanking region, etc. A reference sequence will usually be at least about 18 nt long, more usually at least about 30 nt long, and may extend to the complete sequence that is being compared. Algorithms for sequence analysis are known in the art, such as BLAST, described in Altschul etal. (1990), J. Mol. Biol. 215:403-10. Unless stated otherwise herein, all sequence identity figures provided in this application are determined using the BLAST program at default settings (e.g. w=4; 7M7). The sequences provided herein are essential for recognizing genes encoding PDE interacting protein-related and homologous polynucleotides in database searches. Nucleic acids encoding the subject PDE interacting proteins and polypeptides of the subject invention may be cDNAs or genomic DNAs, as well as fragments thereof. Also provided are genes comprising the subject nucleic acid compositions, where the term "gene" shall be intended to mean the open reading frame encoding specific PDE interacting proteins and polypeptides, and introns, as well as adjacent 5' and 3 ' non-coding nucleotide sequences involved in the regulation of expression, up to about 20 kb beyond the coding region, but possibly further in either direction. The gene may be introduced into an appropriate vector for extrachromosomal maintenance or for integration into a host genome.

The term "cDNA" as used herein is intended to include all nucleic acids that share the arrangement of sequence elements found in native mature mRNA species, where sequence elements are exons and 3 ' and 5 ' non-coding regions. Normally mRNA species have contiguous exons, with the intervening introns, when present, being removed by nuclear RNA splicing, to create a continuous open reading frame encoding an PDE interacting protein. A genomic sequence of interest comprises the nucleic acid present between the initiation codon and the stop codon, as defined in the listed sequences, including all of the introns that are normally present in a native chromosome. It may further include the 3 ' and 5' untranslated regions found in the mature mRNA. It may further include specific transcriptional and translational regulatory sequences, such as promoters, enhancers, etc., including about 1 kb, but possibly more, of flanking genomic DNA at either the 5' or 3' end of the transcribed region. The genomic DNA may be isolated as a fragment of 100 kbp or smaller; and substantially free of flanking chromosomal sequence. The genomic DNA flanking the coding region, either 3 ' or 5', or internal regulatory sequences as sometimes found in introns, contains sequences required for proper tissue and stage specific expression.

The nucleic acid compositions of the subject invention may encode all or a part of the subject PDE interacting proteins and polypeptides, described in greater detail infra. Double or single stranded fragments may be obtained from the DNA sequence by chemically synthesizing oligonucleotides in accordance with conventional methods, by restriction enzyme digestion, by PCR amplification, etc. For the most part, DNA fragments will be of at least 15 nt, usually at least 18 nt or 25 nt, and may be at least about 50 nt.

The genes of the subject invention are isolated and obtained in substantial purity, generally as other than an intact chromosome. Usually, the DNA will be obtained substantially free of other nucleic acid sequences that do not include a sequence encoding a PDE interacting protein or fragment thereof, generally being at least about 50%, usually at least about 90% pure and are typically "recombinant," i.e. flanked by one or more nucleotides with which it is not normally associated on a naturally occurring chromosome.

In addition to the plurality of uses described in greater detail in following sections, the subject nucleic acid compositions find use in the preparation of all or a portion of the PDE interacting polypeptides, as described below.

POLYPEPTIDE COMPOSITIONS

Also provided by the subject invention are PDE interacting proteins and polypeptides, i.e. proteins and polypeptides that are capable of binding to and modulating PDEs, specifically cAMP-PDEs, and more particularly cAMP-PDE4 isoforms, such as PDE4A, PDE4B, PDE4C, PDE4D, and the like. The term polyeptide composition as used herein refers to both the full length proteins as well as portions or fragments thereof. Also included in this term are variations of the naturally occurring proteins, where such variations are homologous or substantially similar to the naturally occurring protein, as described in greater detail below, be the naturally occurring protein the human protein, rat protein, or protein from some other species which naturally expresses an PDE interacting protein, usually a mammalian species. In the following description of the subject invention, the term PDE interacting protein is used to refer not only to the human form of such proteins, but also to homologs thereof expressed in non-human species, e.g. murine, rat and other mammalian species. The subject PDE proteins are, in their natural environment, capable of modulating the form/function of PDEs, as well as targeting PDEs to specific subcellular compartments within a cell. In many embodiments, the subject PDE interacting proteins serve as PDE anchoring proteins.

In many embodiments, the subject proteins are characterized by the presence of one or more coiled domains and leucine zippers. Furthermore, in certain embodiments, e.g. certain rat myomegalin proteins, the subject proteins have a region of high homology with Drosophila centrosomin, whereby high homology is meant at least about 30, usually at least about 40 % sequence identity.

In many embodiments, the proteins range in length from about 1500 to 3000, usually from about 1600 to 2800 and more usually from about 1650 to 2600 amino acid residues, and the projected molecular weight of the subject proteins based solely on the number of amino acid residues in the protein ranges from about 150 to 320, usually from about 160 to 300 kDa, where the actual molecular weight may vary depending on the amount of glycolsylation, if any, of the protein and the apparent molecular weight may be considerably less (40 to 50 kDa) due to SDS binding on gels. On other embodiments, the length of the proteins may be much smaller, e.g. as in the case of splice variants or post translated products, where the length in these proteins may be as short as 40%, usually no shorter than about 50% of the above lengths.

Of particular interest in many embodiments are proteins that are non-naturally glycosylated. By non-naturally glycosylated is meant that the protein has a glycosylation pattern, if present, which is not the same as the glycosylation pattern found in the corresponding naturally occurring protein. For example, a human phosphodiesterase binding protein of the subject invention and of this particular embodiment is characterized by having a glycosylation pattern, if it is glycosylated at all, that differs from that of naturally occurring human PDE binding protein. Thus, the non-naturally glycosylated PDE interacting or binding proteins of this embodiment include non-glycosylated PDE interacting proteins, i.e. proteins having no covalently bound glycosyl groups.

A PDE interacting protein of the subject invention of particular interest is myomegalin, particularly mammalian myomegalin and more particuarly, rat or human myomegalin. In many embodiments, mammalian myomegalin ranges in length from about 2000 to 3000, usually from about 2200 to 2800 and more usually from about 2300 to 2600 aa residues. The projected molecular weight of these myomegalin proteins based solely on the number of amino acid residues in the protein ranges from about 220 to 320, usually from about 220 to 300 and more usually from about 240 to 300 kDa, where the actual molecular weight may vary depending on the amount of glycolsylation, if any, of the protein and the apparent molecular weight may be considerably less (40 to 50 kDa) due to SDS binding on gels. Also of interest are mammalian myomegalin proteins that are shorter than those described above, where these shorter proteins could be splice variants or the products of post-translational activity, and the like.

Of particular interest in certain embodiments is the rat myomegalin protein, where the rat myomegalin protein of the subject invention has an amino acid sequence that is substantially the same as or identical to the sequence appearing as SEQ ID NO:02 infra and appearing in Figure 1. By substantially the same as is meant a protein having a sequence that has at least about 80%, usually at least about 90% and more usually at least about 98% sequence identity with the sequence of SED ED NO:02. Also of particular interest is an approximately 65 kDa rat myomegalin protein expressed in rat testis. Yet another protein of particular interest is the human myomegalin protein of the subject invention which has an amino acid sequence that is substantially the same as or identical to the sequence appearing as SEQ ID NO: 05 infra and appearing in Figure 5. By substantially the same as is meant a protein having a sequence that has at least about 80%, usually at, least about 90% and more usually at least about 98% sequence identity with the sequence of SED LD NO: 05. Another PDE interacting protein of the subject invention of particular interest is M14, particularly mammalian Ml 4, and more particularly, rat or human Ml 4. In many embodiments, mammalian M14 ranges in length from about 1500 to about 2000, usually from about 1600 to about 1800, usually from about 1650 to about 1700, and more usually from about 1670 to about 1690 amino acid residues. The projected molecular weight of these M14 polypeptides, based solely on the number of amino acid residues in the protein, ranges from about 150 to about 200 kDa, usually from about 160 to about 180 kDa, usually from about 165 to about 170 kDa. Rat M14 protein has a mobility on SDS-PAGE of about 185 kDa. The actual molecular weight may vary depending on the amount of glycosylation or other post-translational modifications, if any, of the protein, and the apparent molecular weight may be considerably less (e.g. 40-50 kDa) due to SDS binding on gels. Also of interest are PDE- interacting fragments of the above-described M14 proteins. Of particular interest in certain embodiments is a rat M14 protein, where the rat Ml 4 protein of the subject invention has an amino acid sequence that is substantially the same or identical to the sequence set forth in SEQ ID NO:08 and appearing in Figure 6. By substantially the same as is meant a protein having a sequence that has at least about 80%, usually at least about 90% and more usually at least about 98% sequence identity with the sequence of SED ID NO:08. Proteins homologous to rat M14 are also of interest, including, e.g., an Ese2L protein as described in Sengar et al. (1999) FMBOJ. 18:1159-1171.

Also of interest are huntingtin interacting proteins, and PDE-interacting fragments, variants and homologs thereof. In some embodiments, huntingtin interacting protein (HLP) is a human FflPl protein having an amino acid sequence as disclosed in GenBank Accession No. U79734, The human HIP 1 protein is described in Kalchman et al. ( 1997) Nαtwre Genetics 16:44-53.

In addition to the specific PDE interacting proteins described above, homologs or proteins (or fragments thereof) from other species, i.e. other animal or plant species, are also provided, where such homologs or proteins may be from a variety of different types of species, usually mammals, e.g. rodents, such as mice, rats; domestic animals, e.g. horse, cow, dog, cat; and humans. By homolog is meant a protein having at least about 35 %, usually at least about 40% and more usually at least about 60 % amino acid sequence identity with a specific PDE interacting protein as identified in: (a) SEQ ID NO: 02 and appearing in Figure 1; or (b) SEQ ID NO:05 and appearing in Figure 5; or (c) SEQ ID NO:08 and appearing in Figure 6.

The PDE interacting proteins of the subject invention (e.g. human myomegalin, rat myomegalin or homologs thereof) are present in a non-naturally occurring environment, e.g. are separated from their naturally occurring environment. In certain embodiments, the subject protein is present in a composition that is enriched for the subject protein as compared to the protein in its naturally occurring environment. As such, purified PDE interacting protein is provided, where by purified is meant that PDE interacting protein is present in a composition that is substantially free of non PDE interacting proteins, where by substantially free is meant that less than 90 %, usually less than 60 % and more usually less than 50 % of the composition is made up of non-PDE interacting proteins.

In certain embodiments of interest, the PDE interacting protein is present in a composition that is substantially free of the constituents that are present in its naturally occurring environment. For example, a human PDE interacting protein comprising composition according to the subject invention in this embodiment will be substantially, if not completely, free of those other biological constituents, such as proteins, carbohydrates, lipids, etc., with which it is present in its natural environment. As such, protein compositions of these embodiments will necessarily differ from those that are prepared by purifying the protein from a naturally occurring source, where at least trace amounts of the protein's constituents will still be present in the composition prepared from the naturally occurring source.

The PDE interacting protein of the subject invention may also be present as an isolate, by which is meant that the PDE interacting protein is substantially free of both non-PDE interacting proteins and other naturally occurring biologic molecules, such as oligosaccharides, polynucleotides and fragments thereof, and the like, where substantially free in this instance means that less than 70 %, usually less than 60% and more usually less than 50 % of the composition containing the isolated PDE interacting protein is a non-PDE interacting protein naturally occurring biological molecule. In certain embodiments, the subject protein is present in substantially pure form, where by substantially pure form is meant at least 95%, usually at least 97% and more usually at least 99% pure.

In addition to the naturally occurring proteins, polypeptides which vary from the naturally occurring proteins are also provided. By polypeptides is meant proteins having an amino acid sequence encoded by an open reading frame (ORF) of an gene according to the subject invention, described supra, including the full length protein and fragments thereof, particularly biologically active fragments and/or fragments corresponding to functional domains; and including fusions of the subject polypeptides to other proteins or parts thereof. Fragments of interest will typically be at least about 10 aa in length, usually at least about 50 aa in length, and may be as long as 300 aa in length or longer, but will usually not exceed about 1000 aa in length, where the fragment will have a stretch of amino acids that is identical to the protein of SEQ ID NO:02, SEQ ID NO:05, or SEQ LD NO:08, or a homolog thereof; of at least about 10 aa, and usually at least about 15 aa, and in many embodiments at least about 50 aa in length.

PREPARATION OF PDE INTERACTING POLYPEPTIDES

The subject PDE interacting proteins and polypeptides may be obtained from naturally occurring sources or synthetically produced. Where obtained from naturally occurring sources, the source chosen will generally depend on the species from which the PDE interacting protein is to be derived, e.g. muscle tissue, heart tissue, brain tissue, testis tissue, and the like.

The subject PDE interacting polypeptide compositions may be synthetically derived by expressing a recombinant gene encoding the PDE interacting protein, such as the polynucleotide compositions described above, in a suitable host. For expression, an expression cassette may be employed. The expression vector will provide a transcriptional and translational initiation region, which may be inducible or constitutive, where the coding region is operably linked under the transcriptional control of the transcriptional initiation region, and a transcriptional and translational termination region. These control regions may be native to the gene encoding the particular PDE interacting protein, or may be derived from exogenous sources.

Expression vectors generally have convenient restriction sites located near the promoter sequence to provide for the insertion of nucleic acid sequences encoding heterologous proteins. A selectable marker operative in the expression host may be present. Expression vectors may be used for the production of fusion proteins, where the exogenous fusion peptide provides additional functionality, i.e. increased protein synthesis, stability, reactivity with defined antisera, an enzyme marker, e.g. β-galactosidase, etc.

Expression cassettes may be prepared comprising a transcription initiation region, the gene or fragment thereof, and a transcriptional termination region. Of particular interest is the use of sequences that allow for the expression of functional epitopes or domains, usually at least about 8 amino acids in length, more usually at least about 15 amino acids in length, to about 25 amino acids, and up to the complete open reading frame of the gene. After introduction of the DNA, the cells containing the construct may be selected by means of a selectable marker, the cells expanded and then used for expression.

The subject proteins and polypeptides may be expressed in prokaryotes or eukaryotes in accordance with conventional ways, depending upon the purpose for expression. For large scale production of the protein, a unicellular organism, such as E. coli, B. subtilis, S. cerevisiae, insect cells in combination with baculovirus vectors, or cells of a higher organism such as vertebrates, particularly mammals, e.g. COS 7 cells, may be used as the expression host cells. In some situations, it is desirable to express the subject proteins in eukaryotic cells, where the protein will benefit from native folding and post-translational modifications. Small peptides can also be synthesized in the laboratory. Polypeptides that are subsets of the complete protein sequence may be used to identify and investigate parts of the protein important for function.

Once the source of the protein is identified and/or prepared, e.g. a transfected host expressing the protein is prepared, the protein is then purified to produce the desired PDΕ interacting protein comprising composition. Any convenient protein purification procedures may be employed, where suitable protein purification methodologies are described in Guide to Protein Purification, (Deuthser ed.) (Academic Press, 1990). For example, a lysate may be prepared from the original source, e.g. naturally occurring cells or tissues that express a PDΕ interacting protein or the expression host expressing the PDΕ interacting protein, and purified using HPLC, exclusion chromatography, gel electrophoresis, affinity chromatography, and the like.

USES OF THE SUBJECT POLYPEPTIDE AND NUCLEIC ACID COMPOSITIONS

The subject polypeptide and nucleic acid compositions find use in a variety of different applications, including diagnostic, and therapeutic agent screening/discovery/preparation applications, as well as the treatment of disease conditions associated with PDE interacting protein activity.

GENERAL APPLICATIONS The subject nucleic acid compositions find use in a variety of applications, including:

(a) the identification of PDE interacting protein gene homologs, e.g. myomegalin homologs;

(b) as a source of novel promoter elements; (c) the identification of PDE interacting protein expression regulatory factors; (d) as probes and primers in hybridization applications, e.g. PCR; (e) the identification of expression patterns in biological specimens; (f) the preparation of cell or animal models for PDE interacting protein function; (g) the preparation of in vitro models for PDE interacting protein function; etc.

Identification of homologs

Homologs of the PDE interacting protein gene, e.g. the myomegalin gene, or the M14 gene, are identified by any of a number of methods. A fragment of the provided cDNA may be used as a hybridization probe against a cDNA library from the target organism of interest, where low stringency conditions are used. The probe may be a large fragment, or one or more short degenerate primers. Nucleic acids having sequence similarity are detected by hybridization under low stringency conditions, for example, at 50°C and 6><SSC (0.9 M sodium chloride/0.09 M sodium citrate) and remain bound when subjected to washing at 55°C in 1 xSSC (0.15 M sodium chloride/0.015 M sodium citrate). Sequence identity may be determined by hybridization under stringent conditions, for example, at 50° C or higher and O.lxSSC (15 mM sodium chloride/01.5 mM sodium citrate). Nucleic acids having a region of substantial identity to the provided sequences, e.g. allelic variants, genetically altered versions of the gene, etc., bind to the provided sequences under stringent hybridization conditions. By using probes, particularly labeled probes of DNA sequences, one can isolate homologous or related genes.

Identification of Novel Promoter Elements

The sequence of the 5' flanking region may be utilized for promoter elements, including enhancer binding sites, that provide for regulation in tissues where the subject gene is expressed. The tissue specific expression is useful for determining the pattern of expression, and for providing promoters that mimic the native pattern of expression. Naturally occurring polymorphisms in the promoter region are useful for determining natural variations in expression, particularly those that may be associated with disease.

Identification of Expression Regulatory Factors

Alternatively, mutations may be introduced into the promoter region to determine the effect of altering expression in experimentally defined systems. Methods for the identification of specific DNA motifs involved in the binding of transcriptional factors are known in the art, e.g. sequence similarity to known binding motifs, gel retardation studies, etc. For examples, see Blackwell et al. (1995), Mol. Med. 1: 194-205; Mortlock et al. (1996), Genome Res. 6:327-33; and Joulin and Richard-Foy (1995), Eur. J. Biochem. 232:620-626. The regulatory sequences may be used to identify cis acting sequences required for transcriptional or translational regulation of expression of the subject gene, e.g. the myomegalin gene, especially in different tissues or stages of development, and to identify cis acting sequences and trans-acting factors that regulate or mediate expression of the subject gene. Such transcription or translational control regions may be operably linked to a gene of the subject invention in order to promote expression of wild type or altered PDE interacting protein, e.g. myomegalin, or other proteins of interest in cultured cells, or in embryonic, fetal or adult tissues, and for gene therapy.

Probes and Primers Small DNA fragments are useful as primers for PCR, hybridization screening probes, etc. Larger DNA fragments, i.e. greater than 100 nt are useful for production of the encoded polypeptide, as described in the previous section. For use in amplification reactions, such as PCR, a pair of primers will be used. The exact composition of the primer sequences is not critical to the invention, but for most applications the primers will hybridize to the subject sequence under stringent conditions, as known in the art. It is preferable to choose a pair of primers that will generate an amplification product of at least about 50 nt, preferably at least about 100 nt. Algorithms for the selection of primer sequences are generally known and are available in commercial software packages. Amplification primers hybridize to complementary strands of DNA, and will prime towards each other.

Identification of Expression Patterns in Biological Specimens

The DNA may also be used to identify expression of the gene in a biological specimen. The manner in which one probes cells for the presence of particular nucleotide sequences, as genomic DNA or RNA, is well established in the literature. Briefly, DNA or mRNA is isolated from a cell sample. The mRNA may be amplified by RT-PCR, using reverse transcriptase to form a complementary DNA strand, followed by polymerase chain reaction amplification using primers specific for the subject DNA sequences. Alternatively, the mRNA sample is separated by gel electrophoresis, transferred to a suitable support, e.g. nitrocellulose, nylon, etc., and then probed with a fragment of the subject DNA as a probe. Other techniques, such as oligonucleotide ligation assays, in situ hybridizations, and hybridization to DNA probes arrayed on a solid chip may also find use. Detection of mRNA hybridizing to the subject sequence is indicative of gene expression in the sample.

The Preparation of PDE Interacting Protein Mutants

The sequence of a gene according to the subject invention, including flanking promoter regions and coding regions, may be mutated in various ways known in the art to generate targeted changes in promoter strength, sequence of the encoded protein, etc. The DNA sequence or protein product of such a mutation will usually be substantially similar to the sequences provided herein, i.e. will differ by at least one nucleotide or amino acid, respectively, and may differ by at least two but not more than about ten nucleotides or amino acids. The sequence changes may be substitutions, insertions, deletions, or a combination thereof. Deletions may further include larger changes, such as deletions of a domain or exon. Other modifications of interest include epitope tagging, e.g. with the FLAG system, HA, etc. For studies of subcellular localization, fusion proteins with green fluorescent proteins (GFP) may be used.

Techniques for in vitro mutagenesis of cloned genes are known. Examples of protocols for site specific mutagenesis may be found in Gustin et al. (1993), Biotechniques 14:22; Barany (1985), Gene 37:111-23; Colicelli et al. (1985), Mol. Gen. Genet. 199:537-9; and Prentki et al. (1984), Gene 29:303-13. Methods for site specific mutagenesis can be found in Sambrook et al., Molecular Cloning: A Laboratory Manual, CSH Press 1989, pp. 15.3-15.108; Weiner et α/. (1993), Gene 126:35-41; Sayers et α/. (1992), Biotechniques 13:592-6; Jones and Winistorfer (1992), Biotechniques 12:528-30; Barton et al. (1990), Nucleic Acids Res 18:7349-55; Marotti and Tomich (1989), Gene Anal. Tech. 6:67-70; and Zhu (1989), Anal Biochem 177: 120-4. Such mutated genes may be used to study structure- function relationships of PDE interacting proteins, or to alter properties of the protein that affect its function or regulation. Production of In Vivo Models of PDE Interacting Protein Function

The subject nucleic acids can be used to generate transgenic, non-human animals or site specific gene modifications in cell lines. Transgenic animals may be made through homologous recombination, where the normal PDE interacting protein gene locus is altered. Alternatively, a nucleic acid construct is randomly integrated into the genome. Vectors for stable integration include plasmids, retroviruses and other animal viruses, YACs, and the like.

The modified cells or animals are useful in the study of PDE interacting protein function and regulation. For example, a series of small deletions and/or substitutions may be made in the host's native PDE interacting protein gene to determine the role of different exons in cholesterol metabolism, e.g. cholesterol ester synthesis, cholesterol absorption, etc.

Specific constructs of interest include anti-sense constructs which will block PDE interacting protein expression, expression of dominant negative gene mutations, and over-expression of PDE interacting protein genes. Where a particular genetic sequence is introduced, the introduced sequence may be either a complete or partial sequence of an PDE interacting protein gene native to the host, or may be a complete or partial sequence that is exogenous to the host animal, e.g., a human sequence. A detectable marker, such as lac Z, may be introduced into the locus, where upregulation of gene expression will result in an easily detected change in phenotype.

One may also provide for expression of the gene or variants thereof in cells or tissues where it is not normally expressed, at levels not normally present in such cells or tissues, or at abnormal times of development.

DNA constructs for homologous recombination will comprise at least a portion of the gene native to the species of the host animal, wherein the gene has the desired genetic modification(s), and includes regions of homology to the target locus. DNA constructs for random integration need not include regions of homology to mediate recombination. Conveniently, markers for positive and negative selection are included. Methods for generating cells having targeted gene modifications through homologous recombination are known in the art. For various techniques for transfecting mammalian cells, see Keown et al. (1990), Meth. Enzymol. 185:527-537. For embryonic stem (ES) cells, an ES cell line may be employed, or embryonic cells may be obtained freshly from a host, e.g. mouse, rat, guinea pig, etc. Such cells are grown on an appropriate fibroblast-feeder layer or grown in the presence of leukemia inhibiting factor (LIF). When ES or embryonic cells have been transformed, they may be used to produce transgenic animals. After transformation, the cells are plated onto a feeder layer in an appropriate medium. Cells containing the construct may be detected by employing a selective medium. After sufficient time for colonies to grow, they are picked and analyzed for the occurrence of homologous recombination or integration of the construct. Those colonies that are positive may then be used for embryo manipulation and blastocyst injection. Blastocysts are obtained from 4 to 6 week old superovulated females. The ES cells are trypsinized, and the modified cells are injected into the blastocoel of the blastocyst. After injection, the blastocysts are returned to each uterine horn of pseudopregnant females. Females are then allowed to go to term and the resulting offspring screened for the construct. By providing for a different phenotype of the blastocyst and the genetically modified cells, chimeric progeny can be readily detected.

The chimeric animals are screened for the presence of the modified gene and males and females having the modification are mated to produce homozygous progeny. If the gene alterations cause lethality at some point in development, tissues or organs can be maintained as allogeneic or congenic grafts or transplants, or in in vitro culture. The transgenic animals may be any non-human mammal, such as laboratory animals, domestic animals, etc. The transgenic animals may be used in functional studies, drug screening, etc., e.g. to determine the effect of a candidate drug on PDE interacting binding protein activity and/or the enzymatic activity of the PDE/PDE interacting protein complex.

Production of In Vitro Models of PDE Interacting Protein Function

One can also use the polypeptide compositions of the subject invention to produce in vitro models of PDE interacting protein function. In addition to the subject PDE interacting protein, such models will generally include at least a PDE as well as a cyclic nucleotide, and a means to monitor the activity of the enzyme in the presence of the PDE interacting protein, e.g. a labeled isotope, etc.

DIAGNOSTIC APPLICATIONS Also provided are methods of diagnosing disease states associated with PDE interacting protein activity, e.g. based on observed levels of PDE interacting protein or the expression level of the gene in a biological sample of interest. Samples, as used herein, include biological fluids such as semen, blood, cerebrospinal fluid, tears, saliva, lymph, dialysis fluid and the like; organ or tissue culture derived fluids; and fluids extracted from physiological tissues. Also included in the term are derivatives and fractions of such fluids. The cells may be dissociated, in the case of solid tissues, or tissue sections may be analyzed. Alternatively a lysate ofthe cells may be prepared.

A number of methods are available for determining the expression level of a gene or protein in a particular sample. Diagnosis may be performed by a number of methods to determine the absence or presence or altered amounts of normal or abnormal PDE interacting protein in a patient sample. For example, detection may utilize staining of cells or histological sections with labeled antibodies, performed in accordance with conventional methods. Cells are peπneabilized to stain cytoplasmic molecules. The antibodies of interest are added to the cell sample, and incubated for a period of time sufficient to allow binding to the epitope, usually at least about 10 minutes. The antibody may be labeled with radioisotopes, enzymes, fluorescers, chemiluminescers, or other labels for direct detection. Alternatively, a second stage antibody or reagent is used to amplify the signal. Such reagents are well known in the art. For example, the primary antibody may be conjugated to biotin, with horseradish peroxidase-conjugated avidin added as a second stage reagent. Alternatively, the secondary antibody conjugated to a flourescent compound, e.g. fluorescein, rhodamine, Texas red, etc. Final detection uses a substrate that undergoes a color change in the presence of the peroxidase. The absence or presence of antibody binding may be determined by various methods, including flow cytometry of dissociated cells, microscopy, radiography, scintillation counting, etc.

Alternatively, one may focus on the expression of the gene. Biochemical studies may be performed to determine whether a sequence polymorphism in an coding region or control regions is associated with disease. Disease associated polymorphisms may include deletion or truncation of the gene, mutations that alter expression level, that affect the activity of the protein, etc.

Changes in the promoter or enhancer sequence that may affect expression levels of the gene can be compared to expression levels of the normal allele by various methods known in the art. Methods for determining promoter or enhancer strength include quantitation of the expressed natural protein; insertion of the variant control element into a vector with a reporter gene such as β-galactosidase, luciferase, chloramphenicol acetyltransferase, etc. that provides for convenient quantitation; and the like.

A number of methods are available for analyzing nucleic acids for the presence of a specific sequence, e.g. a disease associated polymorphism. Where large amounts of DNA are available, genomic DNA is used directly. Alternatively, the region of interest is cloned into a suitable vector and grown in sufficient quantity for analysis. Cells that express the subject gene may be used as a source of mRNA, which may be assayed directly or reverse transcribed into cDNA for analysis. The nucleic acid may be amplified by conventional techniques, such as the polymerase chain reaction (PCR), to provide sufficient amounts for analysis. The use of the polymerase chain reaction is described in Saiki, et al. (1985), Science 239:487, and a review of techniques may be found in Sambrook, et al. Molecular Cloning: A Laboratory Manual. CSH Press 1989, pp.14.2B14.33. Alternatively, various methods are known in the art that utilize oligonucleotide ligation as a means of detecting polymorphisms, for examples see Riley etal. (1990), Nucl. Acids Res. 18:2887-2890; and Delahunty et al. (1996), Am. J. Hum. Genet. 58:1239-1246.

A detectable label may be included in an amplification reaction. Suitable labels include fluorochromes, e.g. fluorescein isothiocyanate (FITC), rhodamine, Texas Red, phycoeiythrin, allophycocyanin, 6-carboxyfluorescein (6-FAM), 2',7'-dimethoxy-4',5'-dichloro-6- carboxyfluorescein (JOE), 6-carboxy-X-rhodamine (ROX), 6-carboxy-2',4',7',4,7- hexachlorofluorescein (HEX), 5-carboxyfluorescein (5-FAM) or N,N,N',N'-tetramethyl-6- carboxyrhodamine (TAMRA), radioactive labels, e.g. ³²P, ³⁵S, ³H; etc. The label may be a two stage system, where the amplified DNA is conjugated to biotin, haptens, etc. having a high affinity binding partner, e.g. avidin, specific antibodies, etc., where the-binding partner is conjugated to a detectable label. The label may be conjugated to one or both of the primers. Alternatively, the pool of nucleotides used in the amplification is labeled, so as to incorporate the label into the amplification product.

The sample nucleic acid, e.g. amplified or cloned fragment, is analyzed by one of a number of methods known in the art. The nucleic acid may be sequenced by dideoxy or other methods, and the sequence of bases compared to a wild-type sequence. Hybridization with the variant sequence may also be used to determine its presence, by Southern blots, dot blots, etc. The hybridization pattern of a control and variant sequence to an array of oligonucleotide probes immobilized on a solid support, as described in US 5,445,934, or in WO 95/35505, may also be used as a means of detecting the presence of variant sequences. Single strand conformational polymorphism (SSCP) analysis, denaturing gradient gel electrophoresis (DGGE), and heteroduplex analysis in gel matrices are used to detect conformational changes created by DNA sequence variation as alterations in electrophoretic mobility. Alternatively, where a polymorphism creates or destroys a recognition site for a restriction endonuclease, the sample is digested with that endonuclease, and the products size fractionated to determine whether the fragment was digested. Fractionation is performed by gel or capillary electrophoresis, particularly acrylamide or agarose gels.

Screening for mutations may be based on the functional or antigenic characteristics of the protein. Protein truncation assays are useful in detecting deletions that may affect the biological activity of the protein. Various immunoassays designed to detect polymorphisms in the subject PDE interacting proteins may be used in screening. Where many diverse genetic mutations lead to a particular disease phenotype, functional protein assays have proven to be effective screening tools. The activity of the encoded protein may be determined by comparison with the wild-type protein.

Diagnostic methods of the subject invention in which the level of expression is of interest will typically involve comparison of the PDE interacting protein nucleic acid abundance of a sample of interest with that of a control value to determine any relative differences, where the difference may be measured qualitatively and/or quantitatively, which differences are then related to the presence or absence of an abnormal gene expression pattern. A variety of different methods for determining the nucleic acid abundance in a sample are known to those of skill in the art, where particular methods of interest include those described in: Pietu et al., Genome Res. (June 1996) 6: 492-503; Zhao et al., Gene (April 24, 1995) 156: 207-213; Soares , Curr. Opin. Biotechnol. (October 1997) 8: 542-546; RavaL J. Pharmacol Toxicol Methods (November 1994) 32: 125-127; Chalifour et al., Anal. Biochem (February 1, 1994) 216: 299-304; Stolz & Tuan, Mol. Biotechnol. (December 19960 6: 225- 230; Hong et al., Bioscience Reports (1982) 2: 907; and McGraw, Anal. Biochem. (1984) 143: 298. Also of interest are the methods disclosed in WO 97/27317, the disclosure of which is herein incorporated by reference. SCREENING ASSAYS

The subject PDE interacting proteins and polypeptides find use in various screening assays designed to identify therapeutic agents. The screening assays may be designed to identify agents that modulate, e.g. inhibit or enhance, the activity of the PDE interacting protein directly and thereby modulate the activity of the particular PDE that depends on the presence of the PDE interacting protein for its function. Alternatively, the assay may be designed to identify those agents that modify, e.g. enhance or inhibit, the activity of the PDE when present as a complex with the PDE interacting protein.

Of particular interest are screening methods that provide for qualitative/quantitative measurements of a PDE enzyme activity in the presence of a particular candidate therapeutic agent and its PDE interacting protein, as such screening methods are capable of identifying highly selective PDE modulatory, e.g. inhibitory, agents. For example, the assay could be an assay which measures the activity of a PDE interacting protein/enzyme complex in the presence and absence of a candidate inhibitor agent. In this preferred screening assay embodiment, the PDE interacting protein/PDE complex will generally be a naturally occurring complex, i.e. a complex between a cyclic nucleotide PDE and its naturally occurring PDE interacting protein partner. Of particular interest are complexes between a cAMP-PDE±V and a myomegalin protein.

The screening method may be an in vitro or in vivo format, where both formats are readily developed by those of skill in the art. Depending on the particular method, one or more of, usually one of, the components of the screening assay may be labeled, where by labeled is meant that the components comprise a detectable moiety, e.g. a fluorescent or radioactive tag, or a member of a signal producing system, e.g. biotin for binding to an enzyme-streptavidin conjugate in which the enzyme is capable of converting a substrate to a chromogenic product.

A variety of other reagents may be included in the screening assay. These include reagents like salts, neutral proteins, e.g. albumin, detergents, etc. that are used to facilitate optimal protein-protein binding and/or reduce non-specific or background interactions. Reagents that improve the efficiency of the assay, such as protease inhibitors, nuclease inhibitors, anti-microbial agents, etc. may be used. Specific PDE activity assays of interest include those described in U.S. Patent Nos. 5,798,373 and 5,580,888, the disclosures of which are herein incorporated by reference. A variety of different candidate agents may be screened by the above methods. Candidate agents encompass numerous chemical classes, though typically they are organic molecules, preferably small organic compounds having a molecular weight of more than 50 and less than about 2,500 daltons. Candidate agents comprise functional groups necessary for structural interaction with proteins, particularly hydrogen bonding, and typically include at least an amine, carbonyl, hydroxyl or carboxyl group, preferably at least two of the functional chemical groups. The candidate agents often comprise cyclical carbon or heterocyclic structures and/or aromatic or polyaromatic structures substituted with one or more of the above functional groups. Candidate agents are also found among biomolecules including peptides, saccharides, fatty acids, steroids, purines, pyrimidines, derivatives, structural analogs or combinations thereof.

Candidate agents are obtained from a wide variety of sources including libraries of synthetic or natural compounds. For example, numerous means are available for random and directed synthesis of a wide variety of organic compounds and biomolecules, including expression of randomized oligonucleotides and oligopeptides. Alternatively, libraries of natural compounds in the form of bacterial, fungal, plant and animal extracts are available or readily produced. Additionally, natural or synthetically produced libraries and compounds are readily modified through conventional chemical, physical and biochemical means, and may be used to produce combinatorial libraries. Known pharmacological agents may be subjected to directed or random chemical modifications, such as acylation, alkylation, esterification, amidification, etc. to produce structural analogs.

PDE INTERACTING PROTEIN NUCLEIC ACID AND POLYPEPTIDE THERAPEUTIC COMPOSITIONS The nucleic acid compositions of the subject invention also find use as therapeutic agents in situations where one wishes to enhance the PDE interacting protein activity in a host, e.g. in a mammalian host in which PDE interacting protein activity is sufficiently low such that a disease condition is present, etc. The PDE interacting protein genes, gene fragments, or the encoded proteins or protein fragments are useful in gene therapy to treat disorders associated with defects the PDE interacting protein gene expression. Expression vectors may be used to introduce the gene into a cell. Such vectors generally have convenient restriction sites located near the promoter sequence to provide for the insertion of nucleic acid sequences. Transcription cassettes may be prepared comprising a transcription initiation region, the target gene or fragment thereof, and a transcriptional termination region. The transcription cassettes may be introduced into a variety of vectors, e.g. plasmid; retrovirus, e.g. lentivirus; adenovirus; and the like, where the vectors are able to transiently or stably be maintained in the cells, usually for a period of at least about one day, more usually for a period of at least about several days to several weeks.

The gene or protein may be introduced into tissues or host cells by any number of routes, including viral infection, microinjection, or fusion of vesicles. Jet injection may also be used for intramuscular administration, as described by Furth et al. (1992), Anal Biochem 205:365-368. The DNA may be coated onto gold microparticles, and delivered intradermally by a particle bombardment device, or "gene gun" as described in the literature (see, for example, Tang et al. (1992), Nature 356:152-154), where gold microprojectiles are coated with the DNA, then bombarded into skin cells.

METHODS OF MODULATING PDE INTERACTING PROTEIN ACTIVITY IN A HOST Also provided are methods of regulating, including enhancing and inhibiting, PDE interacting protein activity in a host. Where the PDE interacting protein activity occurs in vivo in a host, an effective amount of active agent that modulates the activity, e.g. reduces the activity, of the PDE interacting protein in vivo (e.g. the activity of the naturally occurring PDE/interacting protein complex), is administered to the host. The active agent may be a variety of different compounds, including a naturally occurring or synthetic small molecule compound, an antibody, fragment or derivative thereof, an antisense composition, and the like.

Naturally occurring or synthetic small molecule compounds of interest include numerous chemical classes, though typically they are organic molecules, preferably small organic compounds having a molecular weight of more than 50 and less than about 2,500 daltons. Candidate agents comprise functional groups necessary for structural interaction with proteins, particularly hydrogen bonding, and typically include at least an amine, carbonyl, hydroxyl or carboxyl group, preferably at least two of the functional chemical groups. The candidate agents often comprise cyclical carbon or heterocyclic structures and/or aromatic or polyaromatic structures substituted with one or more of the above functional groups.

Candidate agents are also found among biomolecules including peptides, saccharides, fatty acids, steroids, purines, pyrimidines, derivatives, structural analogs or combinations thereof. Also of interest as active agent are antibodies that modulate, e.g. reduce, if not inhibit, PDE interacting protein activity in the host. Suitable antibodies are obtained by immunizing a host animal with peptides comprising all or a portion of the subject proteins, such as found in the polypeptide compositions of the subject invention. Suitable host animals include mouse, rat sheep, goat, hamster, rabbit, etc. The origin of the protein immunogen may be mouse, human, rat, monkey etc. The host animal will generally be a different species than the immunogen, e.g. human protein used to immunize mice, etc.

The immunogen may comprise the complete protein, or fragments and derivatives thereof. Preferred immunogens comprise all or a part of the PDE interacting protein, where these residues contain the post-translation modifications, such as glycosylation, found on the native protein. Immunogens comprising the extracellular domain are produced in a variety of ways known in the art, e.g. expression of cloned genes using conventional recombinant methods, isolation from HEC, etc.

For preparation of polyclonal antibodies, the first step is immunization of the host animal with the immunogen, where the immunogen will preferably be in substantially pure form, comprising less than about 1% contaminant. The immunogen may comprise complete PDE interacting protein, fragments or derivatives thereof. To increase the immune response of the host animal, the protein or peptide may be combined with an adjuvant, where suitable adjuvants include alum, dextran, sulfate, large polymeric anions, oil & water emulsions, e.g. Freund's adjuvant, Freund's complete adjuvant, and the like. The immunogen may also be conjugated to synthetic carrier proteins or synthetic antigens. A variety of hosts may be immunized to produce the polyclonal antibodies. Such hosts include rabbits, guinea pigs, rodents, e.g. mice, rats, sheep, goats, and the like. The immunogen is administered to the host, usually intradermally, with an initial dosage followed by one or more, usually at least two, additional booster dosages. Following immunization, the blood from the host will be collected, followed by separation of the serum from the blood cells. The Ig present in the resultant antiserum may be further fractionated using known methods, such as ammonium salt fractionation, DEAE chromatography, and the like.

Monoclonal antibodies are produced by conventional techniques. Generally, the spleen and/or lymph nodes of an immunized host animal provide a source of plasma cells. The plasma cells are immortalized by fusion with myeloma cells to produce hybridoma cells. Culture supernatant from individual hybridomas is screened using standard techniques to identify those producing antibodies with the desired specificity. Suitable animals for production of monoclonal antibodies to the human protein include mouse, rat, hamster, etc. To raise antibodies against the mouse protein, the animal will generally be a hamster, guinea pig, rabbit, etc. The antibody may be purified from the hybridoma cell supernatants or ascites fluid by conventional techniques, e.g. affinity chromatography using PDE-interacting protein bound to an insoluble support, protein A sepharose, etc.

The antibody may be produced as a single chain, instead of the normal multimeric structure. Single chain antibodies are described in Jost et al. (1994) J.B.C. 269:26267-73, and others. DNA sequences encoding the variable region of the heavy chain and the variable region of the light chain are ligated to a spacer encoding at least about 4 amino acids of small neutral amino acids, including glycine and/or serine. The protein encoded by this fusion allows assembly of a functional variable region that retains the specificity and affinity of the original antibody.

For in vivo use, particularly for injection into humans, it is desirable to decrease the antigenicity of the antibody. An immune response of a recipient against the blocking agent will potentially decrease the period of time that the therapy is effective. Methods of humanizing antibodies are known in the art. The humanized antibody may be the product of an animal having transgenic human immunoglobulin constant region genes (see for example International Patent Applications WO 90/10077 and WO 90/04036). Alternatively, the antibody of interest may be engineered by recombinant DNA techniques to substitute the CHI, CH2, CH3, hinge domains, and/or the framework domain with the corresponding human sequence (see WO 92/02190).

The use of Ig cDNA for construction of chimeric immunoglobulin genes is known in the art (Liu et al. (1987) P.N.A.S. 84:3439 and (1987) J. Immunol. 139:3521). mRNA is isolated from a hybridoma or other cell producing the antibody and used to produce cDNA. The cDNA of interest may be amplified by the polymerase chain reaction using specific primers (U.S. Patent nos. 4,683,195 and 4,683,202). Alternatively, a library is made and screened to isolate the sequence of interest. The DNA sequence encoding the variable region of the antibody is then fused to human constant region sequences. The sequences of human constant regions genes may be found in Kabat et al. (1991) Sequences of Proteins of

Tmmiinolngical Interest. N.I.H. publication no. 91-3242. Human C region genes are readily available from known clones. The choice of isotype will be guided by the desired effector functions, such as complement fixation, or activity in antibody-dependent cellular cytotoxicity. Preferred isotypes are IgGl, IgG3 and IgG4. Either of the human light chain constant regions, kappa or lambda, may be used. The chimeric, humanized antibody is then expressed by conventional methods. Antibody fragments, such as Fv, F(ab)₂ and Fab may be prepared by cleavage of the intact protein, e.g. by protease or chemical cleavage. Alternatively, a truncated gene is designed. For example, a chimeric gene encoding a portion of the F(ab)₂ fragment would include DNA sequences encoding the CHI domain and hinge region of the H chain, followed by a translational stop codon to yield the truncated molecule. Consensus sequences of H and L J regions may be used to design oligonucleotides for use as primers to introduce useful restriction sites into the J region for subsequent linkage of V region segments to human C region segments. C region cDNA can be modified by site directed mutagenesis to place a restriction site at the analogous position in the human sequence. Expression vectors include plasmids, retroviruses, YACs, EBV derived episomes, and the like. A convenient vector is one that encodes a functionally complete human CH or CL immunoglobulin sequence, with appropriate restriction sites engineered so that any VH or VL sequence can be easily inserted and expressed. In such vectors, splicing usually occurs between the sphce donor site in the inserted J region and the splice acceptor site preceding the human C region, and also at the sphce regions that occur within the human CH exons. Polyadenylation and transcription termination occur at native chromosomal sites downstream of the coding regions. The resulting chimeric antibody may be joined to any strong promoter, including retroviral LTRs, e.g. SV-40 early promoter, (Okayama et al. (1983) Mol. Cell. Bio. 3:280), Rous sarcoma virus LTR (Gorman et al. (1982) P.N.A.S. 79:6777), and moloney murine leukemia virus LTR (Grosschedl et al. (1985) Cell 41:885); native Ig promoters, etc. In yet other embodiments of the invention, the active agent is an agent that modulates, and generally decreases or down regulates, the expression of the gene in the host. Antisense molecules can be used to down-regulate expression of the protein in cells. The anti-sense reagent may be antisense oligonucleotides (ODN), particularly synthetic ODN having chemical modifications from native nucleic acids, or nucleic acid constructs that express such anti-sense molecules as RNA. The antisense sequence is complementary to the mRNA of the targeted gene, and inhibits expression of the targeted gene products. Antisense molecules inhibit gene expression through various mechanisms, e.g. by reducing the amount of mRNA available for translation, through activation of RNAse H, or steric hindrance. One or a combination of antisense molecules may be administered, where a combination may comprise multiple different sequences. Antisense molecules may be produced by expression of all or a part of the target gene sequence in an appropriate vector, where the transcriptional initiation is oriented such that an antisense strand is produced as an RNA molecule. Alternatively, the antisense molecule is a synthetic oligonucleotide. Antisense oligonucleotides will generally be at least about 7, usually at least about 12, more usually at least about 20 nucleotides in length, and not more than about 500, usually not more than about 50, more usually not more than about 35 nucleotides in length, where the length is governed by efficiency of inhibition, specificity, including absence of cross-reactivity, and the like. It has been found that short oUgonucleotides, of from 7 to 8 bases in length, can be strong and selective inhibitors of gene expression (see Wagner et al. (1996), Nature Biotechnol. 14:840-844). A specific region or regions of the endogenous sense strand mRNA sequence is chosen to be complemented by the antisense sequence. Selection of a specific sequence for the oligonucleotide may use an empirical method, where several candidate sequences are assayed for inhibition of expression of the target gene in an in vitro or animal model. A combination of sequences may also be used, where several regions of the mRNA sequence are selected for antisense complementation.

Antisense oligonucleotides may be chemically synthesized by methods known in the art (see Wagner et al. (1993), supra, and Milligan et al., supra.) Preferred oligonucleotides are chemically modified from the native phosphodiester structure, in order to increase their intracellular stability and binding affinity. A number of such modifications have been described in the literature, which alter the chemistry of the backbone, sugars or heterocycUc bases.

Among useful changes in the backbone chemistry are phosphorothioates; phosphorodithioates, where both of the non-bridging oxygens are substituted with sulfur; phosphoroamidites; alkyl phosphotriesters and boranophosphates. Achiral phosphate derivatives include 3 '-O'-5 '-S-phosphorothioate, 3 '-S-5 '-O-phosphorothioate, 3 '-CH₂-5 '-O- phosphonate and 3'-NH-5'-O-phosphoroamidate. Peptide nucleic acids replace the entire ribose phosphodiester backbone with a peptide linkage. Sugar modifications are also used to enhance stability and affinity. The α-anomer of deoxyribose may be used, where the base is inverted with respect to the natural β-anomer. The 2'-OH of the ribose sugar may be altered to form 2'-O-methyl or 2'-O-allyl sugars, which provides resistance to degradation without comprising affinity. Modification of the heterocyclic bases must maintain proper base pairing. Some useful substitutions include deoxyuridine for deoxythymidine; 5-methyl-2'- deoxycytidine and 5-bromo-2'-deoxycytidine for deoxycytidine. 5- propynyl-2 '-deoxyuridine and 5-propynyl-2 '-deoxycytidine have been shown to increase affinity and biological activity when substituted for deoxythymidine and deoxycytidine, respectively.

As an alternative to anti-sense inhibitors, catalytic nucleic acid compounds, e.g. ribozymes, anti-sense conjugates, etc. may be used to inhibit gene expression. Ribozymes may be synthesized in vitro and administered to the patient, or may be encoded on an expression vector, from which the ribozyme is synthesized in the targeted cell (for example, see International patent application WO 9523225, and Beigelman et al. (1995), Nucl. Acids Res. 23:4434-42). Examples of oligonucleotides with catalytic activity are described in WO 9506764. Conjugates of anti-sense ODN with a metal complex, e.g. terpyridylCu(II), capable of mediating mRNA hydrolysis are described in Bashkin et al. (1995), Appl. Biochem. Biotechnol. 54:43-56.

As mentioned above, an effective amount of the active agent is administered to the host, where "effective amount" means a dosage sufficient to produce a desired result, where the desired result in the desired modulation, e.g. enhancement, reduction, of PDE interacting protein activity, which in turn leads to a desired effect on the state of the disease condition being treated, e.g. a reduction in the level of inflammation, etc.

In the subject methods, the active agent(s) may be administered to the host using any convenient means capable of resulting in the desired inhibition of PDE interacting protein activity. Thus, the agent can be incorporated into a variety of formulations for therapeutic administration. More particularly, the agents of the present invention can be formulated into pharmaceutical compositions by combination with appropriate, pharmaceutically acceptable carriers or diluents, and may be formulated into preparations in solid, semi-solid, liquid or gaseous forms, such as tablets, capsules, powders, granules, ointments, solutions, suppositories, injections, inhalants and aerosols. As such, administration of the agents can be achieved in various ways, including oral, buccal, rectal, parenteral, intraperitoneal, intradermaL transdermal, intracheal,etc, administration.

In pharmaceutical dosage forms, the agents may be administered in the form of their pharmaceutically acceptable salts, or they may also be used alone or in appropriate association, as well as in combination, with other pharmaceutically active compounds. The foUowing methods and excipients are merely exemplary and are in no way limiting.

For oral preparations, the agents can be used alone or in combination with appropriate additives to make tablets, powders, granules or capsules, for example, with conventional additives, such as lactose, mannitol, corn starch or potato starch; with binders, such as crystalhne cellulose, cellulose derivatives, acacia, corn starch or gelatins; with disintegrators, such as corn starch, potato starch or sodium carboxymethylcellulose; with lubricants, such as talc or magnesium stearate; and if desired, with diluents, buffering agents, moistening agents, preservatives and flavoring agents. The agents can be formulated into preparations for injection by dissolving, suspending or emulsifying them in an aqueous or nonaqueous solvent, such as vegetable or other similar oils, synthetic aliphatic acid glycerides, esters of higher aUphatic acids or propylene glycol; and if desired, with conventional additives such as solubiUzers, isotonic agents, suspending agents, emulsifying agents, stabiUzers and preservatives. The agents can be utilized in aerosol formulation to be administered via inhalation.

The compounds of the present invention can be formulated into pressurized acceptable propellants such as dichlorodifluoromethane, propane, nitrogen and the Uke.

Furthermore, the agents can be made into suppositories by mixing with a variety of bases such as emulsifying bases or water-soluble bases. The compounds of the present invention can be administered rectally via a suppository. The suppository can include vehicles such as cocoa butter, carbowaxes and polyethylene glycols, which melt at body temperature, yet are solidified at room temperature.

Unit dosage forms for oral or rectal administration such as syrups, elixirs, and suspensions may be provided wherein each dosage unit, for example, teaspoonful, tablespoonful, tablet or suppository, contains a predetermined amount of the composition containing one or more inhibitors. Similarly, unit dosage forms for injection or intravenous administration may comprise the inhibitor(s) in a composition as a solution in sterile water, normal saline or another pharmaceutically acceptable carrier.

The term "unit dosage form," as used herein, refers to physically discrete units suitable as unitary dosages for human and animal subjects, each unit containing a predetermined quantity of compounds of the present invention calculated in an amount sufficient to produce the desired effect in association with a pharmaceutically acceptable diluent, carrier or vehicle. The specifications for the novel unit dosage forms of the present invention depend on the particular compound employed and the effect to be achieved, and the pharmacodynamics associated with each compound in the host. The pharmaceutically acceptable excipients, such as vehicles, adjuvants, carriers or diluents, are readily available to the public. Moreover, pharmaceutically acceptable auxiliary substances, such as pH adjusting and buffering agents, tonicity adjusting agents, stabilizers, wetting agents and the Uke, are readily available to the public.

Where the agent is a polypeptide, polynucleotide, analog or mimetic thereof, e.g. antisense composition, it may be introduced into tissues or host cells by any number of routes, including viral infection, microinjection, or fusion of vesicles. Jet injection may also be used for intramuscular administration, as described by Furth et al. (1992), Anal Biochem 205:365- 368. The DNA may be coated onto gold microparticles, and delivered intradermally by a particle bombardment device, or "gene gun" as described in the literature (see, for example, Tang et al. (1992), Nature 356: 152-154), where gold microprojectiles are coated with the DNA, then bombarded into skin cells.

Those of skiU in the art will readily appreciate that dose levels can vary as a function of the specific compound, the severity of the symptoms and the susceptibility of the subject to side effects. Preferred dosages for a given compound are readily determinable by those of skill in the art by a variety of means.

The subject methods find use in the treatment of a variety of different disease conditions involving PDE interacting protein activity, particularly in those disease conditions in which the selective inhibition of PDE activity, more particularly PDEIV activity, results in treatment of the disease condition where targeting of the PDE interacting protein by the therapeutic agent results in modulated, e.g. reduced or enhanced, activity of its corresponding PDE. Specific disease of interest as treatable by the subject methods include: asthma, including inflamed lung associate asthma, cystic fibrosis, inflammatory airway disease, chronic bronchitis, eosinophiUc granuloma, psoriasis and other benign and maUgnant proliferative skin diseases, endotoxic shock, septic shock, ulcerative colitis, Crohn's disease, reperfusion injury, or the myocardium and brain, inflammatory arthritis, chronic gloerulonephritis, atopic dermatitis, urticaria, adult respiratory distress syndrome, diabetes insipidus, allergic rhinitis, aUergic conjunctivitis, vernal conjunctivitis, arterial restinosis and artherosclerosis, inflammatory diseases associated with irritation and pain, rheumatoid arthritis, ankylosing spondylitis, transplant rejection and graft versus host disease, disease conditions associated with hypersecretion of gastric acid, disease conditions in which cytokines are mediators, e.g. sepsis, and septic shock, and the Uke.

By treatment is meant at least an amelioration of the symptoms associated with the pathological condition afflicting the host, where amelioration is used in a broad sense to refer to at least a reduction in the magnitude of a parameter, e.g. symptom, associated with the pathological condition being treated, such as inflammation, etc. As such, treatment also includes situations where the pathological condition, or at least symptoms associated therewith, are completely inhibited, e.g. prevented from happening, or stopped, e.g. terminated, such that the host no longer suffers from the pathological condition, or at least the symptoms that characterize the pathological condition. A variety of hosts are treatable according to the subject methods. Generally such hosts are "mammals" or "mammalian," where these terms are used broadly to describe organisms which are within the class mammalia, including the orders carnivore (e.g., dogs and cats), rodentia (e.g., mice, guinea pigs, and rats), and primates (e.g., humans, chimpanzees, and monkeys). In many embodiments, the hosts will be humans. Kits with unit doses of the active agent, usually in oral or injectable doses, are provided. In such kits, in addition to the containers containing the unit doses will be an informational package insert describing the use and attendant benefits of the drugs in treating pathological condition of interest. Preferred compounds and unit doses are those described herein above.

The following examples are offered primarily for purposes of illustration. It wiU be readily apparent to those skilled in the art that the formulations, dosages, methods of administration, and other parameters of this invention may be further modified or substituted in various ways without departing from the spirit and scope of the invention.

EXPERIMENTAL I. S creening of the yeast two hybrid system cDNA brain library

To identify proteins that interact with a PDE4, cDNA coding for the amino terminus of PDE4D3 or for a region corresponding to a.a. 114-672 were inserted into pGBT9 vectors and used for screening of a Matchmaker rat brain library subcloned in pGADIO vector (Clontech, Palo Alto, CA). The fragment encoding the autoinhibitory (UCR2), catalytic, and carboxy terminal domains of rPDE4D3 (aa 114-672) was amplified by PCR with the full- length cDNA using the following forward and reverse primers with incorporated restriction sites and Stop codon. EcoRI: 5' CGG AAT TCG AGG AGG CCT ACC AGA AAC 3' (GUPA4) (SEQ ID NO:06) and Sall/TAG: 5' TGA GTC GAC TAC GTG TCA AGG CAA CAA TGG TC 3' (GUPA3) (SEQ ID NO:07). The PCR products were cloned into EcoRI/Sall site of pGBT9 (Clontech) downstream of the Gal4 activation domain. The PCR was performed in presence of recombinant Pfu polymerase (Stratagene) at low cycle number (10 cycles) to ensure high fidelity reading. The insertions were entirely sequenced to confirm the correct reading frame and the sequence. Sequencing was performed by the Molecular Biology faciUty at Stanford University using the ABI PRISM Dye Terminator Cycle Sequencing Ready Reaction Kit with AmpliTaq DNA Polymerase, FS (Perkin Elmer).

Of the positive clones isolated from the screening of the rat brain library, 187 gave strong positive signal while 81 gave only a weak signal. Of the strong positive clones, PBP46 was further characterized. This clone contained an insert of aprroximately 2.8 kb. The interaction of the clone with the PDE was confirmed by subcloning the cDNA fragment in both pGBT9 and pGADIO and by testing growth and β-galactosidase activity in the yeast two hybrid system. The clone continued to show strong interaction with the 1.6 fragment of PDE4D3.

II. Screening for the full length myomegalin clone A homology search (BLAST) using the sequence of PBP46 clone showed no significant identity to sequences in any public domain database. This clone was then used to probe a blot with RNA from multiple tissues. A transcript of approximately 8.0-8.5 kb hybridized to the probe in several tissues, the highest level of expression being observed in the rat skeletal muscle and heart. Lower levels of expression were detected in brain, liver and lung. In the testis a transcript of 2.0-2.4 kb was consistently observed. The expression in the testis was confirmed by PCR and by screening a rat testis library. Two clones containing the 3' end sequence of myomegalin were retrieved from this library.

To obtain the complete sequence of the 8.0-8.5 transcript, a rat skeletal muscle cDNA Ubrary was screened with the PBP46 cDNA. From this screening, 2 clones were retrieved. However, the clones did not yield a complete ORF. Screening was then repeated six more times with oligonucleotides corresponding to the 5' end of the longest clones. From this multiple screening, 21 overlapping clones were obtained. Merging of the sequences from the different clones yielded a 9 kb sequence, a size in agreement with the size of the transcript derived from rat heart and skeletal muscles. See Fig. 2. Conceptual translation of the nucleotide sequence uncovered an open reading frame of a protein of 2324 amino acids corresponding to a calculated MW of 261 kDa. See Fig. 1. To analyze tissue distribution of the rat myomegalin transcripts, Northern blot analysis was performed using radioactively labeled probes corresponding to the 3' end (probe 1; 1000 bp) and the 5' end (probe 2; 665 bp) of the myomegalin open reading frame. Transcripts of various sizes were found in various tissues using either probe 1 or probe 2 or both. The results indicated that there are at least four different transcripts of rat myomegaUn: two expressed in heart (7.5 and 5.9 kb); two in skeletal muscle (7.5 and 4.3 kb) and one in testis (2.5 kb). The 2.5 kb variant roughly corresponds to the PBP46 clone, and is expressed exclusively in rat testis.

in. Screening of the EST/database To determine whether mouse or human sequences analogous to the rat myomegaUn are present in public domain databases, the rat sequence was used for a BLAST search of GenBank and EST Ubraries. The following EST were retrieved. AA755885, AA110441, W23471, AA333456, AA489265. These sequences are more than 90% homologous to the rat sequence. Sequence AL021920 contains a genomic fragment from human chromosome lp35. l-p36.21. Several exons overlap with the rat sequence from residue 1215 until residue 1444. Thus myomegaUn must reside on human chromosome lp35. l-p36. KIAA0454 (accession # AB007923), KIAA0477 (acccesion # AB007946) are two clones containing portion of the human myomegalin sequence since they are more than 90% homologous to the rat ORF. These human clones were merged to obtain a full length human sequence homologous to myomegalin. See Fig. 4. The human open reading frame coded for a protein of 2517 residues and a calculated molecular weight of 282.1 kDa. See Fig. 5. AUgnment of the human and rat sequence showed identity from aa 235 of rat myomegaUn to the end. In the amino terminus region, the two sequences showed only weak homologies. The reason for this discrepancy is at present unclear. It is possible that it is due to species differences. The junction where the rat sequence diverges from the human was derived from four clones isolated from the rat skeletal muscle library, lessening the possibility that cloning artifact is at the basis of this discrepancy. The presence of the junction was further confirmed by PCR analysis of rat heart mRNA (data not shown). However, further blast searches with the region encompassing the 5' end of myomegalin did not yield mouse EST fragments overlapping the junction. Conversely, several EST clones confirming the human junction were retrieved from human and mouse EST databases.

IV. Protein/protein interaction

Several attempts were made to confirm the interaction between myomegalin and PDE4D3. However, due to the insolubility of the fuU length or truncated myomegalin immunoprecipitation experiments could not be performed. In an alternative approach, PBP46 was cotransfected with PDE4D3 in COS 7 cells and the PDE activity was determined in the particulate fraction of the cell. If PDE4D3 interacts with PBP46, an increase in the particulate PDE activity would be expected. Two to three fold increase in the particulate PDE4D3 activity was detected when plasmids containing PBP46 and PDE4D3 were cotransfected in COS7 ceUs.

V. Subcellular localization of myomegaUn

To investigate the subcellular localization of myomegalin the PBP46 clone was subcloned in frame to a flag tag and expressed in COS7 cells. The recombinant protein thus obtained was entirely recovered in the particulatefraction and could be extracted only with buffer containing SDS. Expression in transfected cells was further assessed by immunofluorescence (IF) using the flag antibody. The flag tagged recombinant protein encoded in PBP46 was entirely locaUzed in the Golgi/centrosomal region of COS7 cells. No attempts were made to express the full-length myomegaUn cDNA.

VI. Western blot analysis of muscle and testis extracts Polyclonal antibodies were raised in rabbit against peptides corresponding to the carboxyl terminus region of myomegalin. These antibodies recognize in testis a protein of approximately 64 kDa. In heart and muscle, proteins of 280,250 and 200 kDa were observed. It is at present unknown whether these are native proteins or products of proteolysis. When these antibodies were used for IF localization, a region corresponding to the Golgi/centrosomal region is intensely labeled.

It is apparent from the above results and discussion that polynucleotides encoding novel mammalian PDE interacting proteins, such as myomegaUn, as well as the novel polypeptides encoded thereby, are provided. The subject invention is important for both research and therapeutic applications. For example, identification of the subject PDE interacting proteins provides for the ability to screen potential PDE inhibitors with PDE/PDE interacting protein complexes, where the results of such screening procedures should be more indicative of in vivo activity of a potential agent than screening procedures in which PDE is used by itself. Accordingly, the subject invention provides for a significant contribution to the art.

AU publications and patent applications cited in this specification are herein incorporated by reference as if each individual publication or patent application were specificaUy and individually indicated to be incorporated by reference. The citation of any pubUcation is for its disclosure prior to the filing date and should not be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A polynucleotide present in other than its natural environment encoding a PDE interacting polypeptide.

2. The polynucleotide according to Claim 1, wherein said polynucleotide encodes a myomegaUn protein.

3. A fragment of a polynucleotide according to Claim 1.

4. An PDE interacting polypeptide present in other than its naturally occurring environment.

5. The polypeptide according to Claim 4, wherein said polypeptide is a myomegaUn protein.

6. A fragment of a polypeptide according to Claim 4.

7. Substantially pure PDE interacting protein.

8. Isolated PDE interacting protein.

9. An expression cassette comprising a transcriptional initiation region functional in an expression host, a polynucleotide having a nucleotide sequence found in the nucleic acid according to Claim 1 under the transcriptional regulation of said transcriptional initiation region, and a transcriptional termination region functional in said expression host.

10. A cell comprising an expression cassette according to Claim 9 as part of an extrachromosomal element or integrated into the genome of a host cell as a result of introduction of said expression cassette into said host cell.

11. The cellular progeny of the cell according to Claim 10.

12. A method of producing an PDE interacting polypeptide, said method comprising: growing a cell according to Claim 10, whereby said polypeptide is expressed; and isolating said polypeptide substantially free of other proteins.

13. A monoclonal antibody binding specifically to a PDE interacting protein.

14. The monoclonal antibody according to Claim 13, wherein said antibody inhibits the activity of at least one of PDE or a PDE interacting protein.

15. The monoclonal antibody according to Claim 13, wherein said antibody is a humanized antibody.

16. A method of determining whether an agent modulates the activity of a PDE, said method comprising: contacting a complex of said PDE and a PDE interacting protein with said agent; and determining the effect of said agent on the activity of said PDE.

17. The method according to Claim 16, wherein said agent is a small molecule.

18. The method according to Claim 16, wherein said agent is an antibody.

19. The method according to Claim 18, wherein said agent is a monoclonal antibody.

20. A method for modulating the activity of a PDE interacting protein, said method comprising: contacting said PDE interacting protein with an agent that modulates the activity of said PDE interacting protein.