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Title:  Antibodies against gene products related to Werner's Syndrome
United States Patent: 
7,285,641
Issued: 
October 23, 2007

Inventors: 
Fu; Ying-Hui (Seattle, WA), Yu; Chang-En (Seattle, WA), Oshima; Junko (Seattle, WA), Mulligan; John T (Seattle, WA), Schellenberg; Gerard D (Seattle, WA)
Appl. No.: 
10/374,077
Filed: 
February 25, 2003


 

Pharm Bus Intell & Healthcare Studies


Abstract

The present invention discloses antibodies that specifically bind to a WRN gene product or a portion thereof.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, the present invention provides isolated nucleic acid molecules encoding the WRN gene, as well as portions thereof, representative of which are provided in the Figures (see Original Patent). The protein which is encoded by the WRN gene is referred to hereinafter as the "WRN protein". Within other embodiments, nucleic acid molecules are provided which encode a mutant WRN gene product that increases the probability of Werner's Syndrome (in a statistically significant manner). Representative illustrations of such mutants are provided in Example 3.

Within other aspects of the present invention, isolated nucleic acid molecules are provided, selected from the group consisting of (a) an isolated nucleic acid molecule as set forth in the Figures (see Original Patent), or complementary sequence thereof, (b) an isolated nucleic acid molecule that specifically hybridizes to the nucleic acid molecule of (a) under conditions of high stringency, and (c) an isolated nucleic acid that encodes a WRN gene product (WRN protein). As utilized herein, it should be understood that a nucleic acid molecule hybridizes "specifically" to an WRN gene (or related sequence) if it hybridizes detectably to such a sequence, but does not significantly or detectably hybridize to the Bloom's Syndrome gene (Ellis et al., Cell 83:655-666, 1995).

Within other aspects, expression vectors are provided comprising a promoter operably linked to one of the nucleic acid molecule described above. Representative examples of suitable promoters include tissue-specific promoters, as well as promoters such as the CMV I-E promoter, SV40 early promoter and MuLV LTR. Within related aspects, viral vectors are provided that are capable of directing the expression of a nucleic acid molecule as described above. Representative examples of such viral vectors include herpes simplex viral vectors, adenoviral vectors, adenovirus-associated viral vectors and retroviral vectors. Also provided are host cells (e.g., human, dog, monkey, rat or mouse cells) which carry the above-described vectors.

Within other aspects of the present invention, isolated proteins or polypeptides are provided comprising a WRN gene product, as well as peptides of greater than 12, 13 or 20 amino acids. Within another embodiment, the protein is a mutant WRN gene product that increases the probability of Werner's Syndrome.

Within yet another aspect of the present invention, methods of treating or preventing Werner's Syndrome are provided (as well as for related diseases which are discussed in more detail below), comprising the step of administering to a patient a vector containing or expressing a nucleic acid molecule as described above, thereby reducing the likelihood or delaying the onset of Werner's Syndrome (or the related disease) in the patient. Within a related aspect, methods of treating or preventing Werner's Syndrome (and related diseases) are provided, comprising the step of administering to a patient a protein as described above, thereby reducing the likelihood or delaying the onset of Werner's Syndrome (or a related disease) in the patient. Within certain embodiments, the above methods may be accomplished by in vivo administration.

Also provided by the present invention are pharmaceutical compositions comprising a nucleic acid molecule, vector, host cell, protein, or antibody as described above, along with a pharmaceutically acceptable carrier or diluent.

Within other aspects of the present invention, antibodies are provided which specifically bind to an WRN protein or to unique peptides derived therefrom. As utilized herein, it should be understood that an antibody is specific for an WRN protein (or peptide) if it binds detectably, and with a K.sub.d of 10.sup.-7M or less (e.g., 10.sup.-8M, 10.sup.-9M, etc.), but does not bind detectably (or with an affinity of greater than 10.sup.-7M, (e.g., 10.sup.-6M, 10.sup.-5M, etc.) to an unrelated helicase (e.g., the Bloom's Syndrome gene, supra). Also provided are hybridomas which are capable of producing such antibodies.

Within other aspects of the present invention, nucleic acid probes are provided which are capable of specifically hybridizing (as defined below) to an WRN gene under conditions of high stringency. Within one related aspect, such probes comprise at least a portion of the nucleotide sequence shown in the Figures (see Original Patent), or its complementary sequence, the probe being capable of specifically hybridizing to a mutant WRN gene under conditions of high stringency. Representative probes of the present invention are generally at least 12 nucleotide bases in length, although they may be 14, 16, 18 bases or longer. Also provided are primer pairs capable of specifically amplifying all or a portion of any of the nucleic acid molecules disclosed herein.

Within other aspects of the invention, methods are provided for diagnosing a patient having an increased likelihood of contracting Werner's Syndrome (or a related disease), comprising the steps of (a) obtaining from a patient a biological sample containing nucleic acid, (b) incubating the nucleic acid with a probe which is capable of specifically hybridizing to a mutant WRN gene under conditions and for time sufficient to allow hybridization to occur, and (c) detecting the presence of hybridized probe, and thereby determining that said patient has an increased likelihood of contracting Werner's Syndrome (or a related disease). Within another aspect, methods are provided comprising the steps of (a) obtaining from a patient a biological sample containing nucleic acid, (b) amplifying a selected nucleic acid sequence associated with a mutant WRN gene, and (c) detecting the presence of an amplified nucleic acid sequence, and thereby determining that the patient has an increased likelihood of contracting Werner's Syndrome (or a related disease). Suitable biological samples include nucleated cells obtained from the peripheral blood, from buccal swabs, or brain tissue.

Within another aspect, peptide vaccines are provided which comprise a portion of a mutant WRN gene product containing a mutation, in combination with a pharmaceutically acceptable carrier or diluent.

Within yet another aspect, transgenic animals are provided whose germ cells and somatic cells contain a WRN gene (or lack thereof, i.e., a "knockout") which is operably linked to a promoter effective for the expression of the gene, the gene being introduced into the animal, or an ancestor of the animal, at an embryonic stage. Within one embodiment, the animal is a mouse, rat or dog. Within other embodiments, the WRN gene is expressed from a vector as described above. Within yet another embodiment, the WRN gene encodes a mutant WRN gene product.

These and other aspects of the present invention will become evident upon reference to the following detailed description and attached drawings. In addition, various references are set forth herein which describe in more detail certain procedures or compositions (e.g., plasmids, etc.), and are therefore incorporated by reference in their entirety.

DETAILED DESCRIPTION OF THE INVENTION

Genes and Gene Products Related to Werner's Syndrome

The present invention provides isolated nucleic acid molecules comprising a portion of the gene which is implicated in the onset of WS. Briefly, as can be seen from FIG. 4 (see Original Patent), this gene encodes a protein that is similar in amino acid sequence to several known ATP-dependent DNA helicases (enzymes that unwind the DNA duplex). It is less similar to known RNA-DNA helicases. Helicases are involved in the replication of DNA, often binding the replication origin, and/or the replication complex. In addition, the single stranded DNA that is involved in recombination can be generated by DNA helicases.

Although various aspects of the WRN gene (or portions thereof) are shown in the Figures (see Original Patent), it should be understood that within the context of the present invention, reference to one or more of these genes includes derivatives of the genes that are substantially similar to the genes (and, where appropriate, the proteins (including peptides and polypeptides) that are encoded by the genes and their derivatives). As used herein, a nucleotide sequence is deemed to be "substantially similar" if: (a) the nucleotide sequence is derived from the coding region of the described genes and includes, for example, portions of the sequence or allelic variations of the sequences discussed above, or alternatively, encodes a helicase-like activity (Bjornson et al., Biochem. 3307:14306-14316, 1994); (b) the nucleotide sequence is capable of hybridization to nucleotide sequences of the present invention under high or very high stringency (see Sambrook et al., Molecular Cloning: A Laboratory Manual, 2nd ed., Cold Spring Harbor Laboratory Press, NY, 1989); or (c) the DNA sequences are degenerate as a result of the genetic code to the DNA sequences defined in (a) or (b). Further, the nucleic acid molecule disclosed herein includes both complementary and non-complementary sequences, provided the sequences otherwise meet the criteria set forth herein. Within the context of the present invention, high stringency means standard hybridization conditions (e.g., 5.times.SSPE, 0.5% SDS at 65.degree. C., or the equivalent) while very high stringency means conditions of hybridization such that the nucleotide sequence is able to selectively hybridize to a single allele of the WS-related gene.

The WRN gene may be isolated from genomic DNA or cDNA. Genomic DNA libraries constructed in chromosomal vectors, such as YACs (yeast artificial chromosomes), bacteriophage vectors, such as .lamda.EMBL3, .lamda.gt10, cosmids, or plasmids are suitable for use. cDNA libraries constructed in bacteriophage vectors, plasmids, or others, are suitable for screening. Such libraries may be constructed using methods and techniques known in the art (see Sambrook et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Press, 1989) or purchased from commercial sources (e.g., Clontech, Palo Alto, Calif.). Within one embodiment, the WRN gene is isolated by PCR performed on genomic DNA, cDNA or DNA from libraries, or is isolated by probe hybridization of genomic DNA or cDNA libraries. Primers for PCR and probes for hybridization screening may be designed based on the DNA sequence of WRN presented herein. The DNA sequence of a portion of the WRN gene and the entire coding sequence is presented in the Figures. Primers for PCR should be derived from sequences in the 5' and 3' untranslated region in order to isolate a full-length cDNA. The primers should not have self-complementary sequences nor have complementary sequences at their 3' end (to prevent primer-dimer formation). Preferably, the primers have a GC content of about 50% and contain restriction sites. The primers are annealed to cDNA and sufficient cycles of PCR are performed to yield a product readily visualized by gel electrophoresis and staining. The amplified fragment is purified and inserted into a vector, such as .lamda.gt10 or pBS (M13+), and propagated. An oligonucleotide hybridization probe suitable for screening genomic or cDNA libraries may be designed based on the sequence provided herein. Preferably, the oligonucleotide is 20-30 bases long. Such an oligonucleotide may be synthesized by automated synthesis. The oligonucleotide may be conveniently labeled at the 5' end with a reporter molecule, such as a radionuclide, (e.g., .sup.32P) or biotin. The library is plated as colonies or phage, depending upon the vector, and the recombinant DNA is transferred to nylon or nitrocellulose membranes. Following denaturation, neutralization, and fixation of the DNA to the membrane, the membranes are hybridized with the labeled probe. The membranes are washed and the reporter molecule detected. The hybridizing colonies or phage are isolated and propagated. Candidate clones or PCR amplified fragments may be verified as containing WRN DNA by any of various means. For example, the candidate clones may be hybridized with a second, nonoverlapping probe or subjected to DNA sequence analysis. In these ways, clones containing WRN gene, which are suitable for use in the present invention are isolated.

The structure of the proteins encoded by the nucleic acid molecules described herein may be predicted from the primary translation products using the hydrophobicity plot function of, for example, P/C Gene, Lasergen System, DNA STAR, Madison, Wis., or according to the methods described by Kyte and Doolittle (J. Mol. Biol. 157:105-132, 1982).

WRN proteins of the present invention may be prepared in the form of acidic or basic salts, or in neutral form. In addition, individual amino acid residues may be modified by oxidation or reduction. Furthermore, various substitutions, deletions, or additions may be made to the amino acid or nucleic acid sequences, the net effect of which is to retain or further enhance or decrease the biological activity of the mutant or wild-type protein. Moreover, due to degeneracy in the genetic code, for example, there may be considerable variation in nucleotide sequences encoding the same amino acid sequence.

Other derivatives of the WRN proteins disclosed herein include conjugates of the proteins along with other proteins or polypeptides. This may be accomplished, for example, by the synthesis of N-terminal or C-terminal fusion proteins which may be added to facilitate purification or identification of WRN proteins (see U.S. Pat. No. 4,851,341; see also, Hopp et al., Bio/Technology 6:1204, 1988.) Alternatively, fusion proteins such as WRN protein-.beta.-galactosidase or WRN protein-luciferase may be constructed in order to assist in the identification, expression, and analysis of WRN proteins.

WRN proteins of the present invention may be constructed using a wide variety of techniques described herein. Further, mutations may be introduced at particular loci by synthesizing oligonucleotides containing a mutant sequence, flanked by restriction sites enabling ligation to fragments of the native sequence. Following ligation, the resulting reconstructed sequence encodes a derivative having the desired amino acid insertion, substitution, or deletion.

Alternatively, oligonucleotide-directed site-specific (or segment specific) mutagenesis procedures may be employed to provide an altered gene having particular codons altered according to the substitution, deletion, or insertion required. Exemplary methods of making the alterations set forth above are disclosed by Walder et al. (Gene 42:133, 1986); Bauer et al. (Gene 37:73, 1985); Craik (BioTechniques, January 1985, 12-19); Smith et al. (Genetic Engineering: Principles and Methods, Plenum Press, 1981); and Sambrook et al. (supra). Deletion or truncation derivatives of WRN proteins (e.g., a soluble extracellular portion) may also be constructed by utilizing convenient restriction endonuclease sites adjacent to the desired deletion. Subsequent to restriction, overhangs may be filled in, and the DNA religated. Exemplary methods of making the alterations set forth above are disclosed by Sambrook et al. (Molecular Cloning: A Laboratory Manual, 2d Ed., Cold Spring Harbor Laboratory Press, 1989).

Mutations of the present invention preferably preserve the reading frame of the coding sequences. Furthermore, the mutations will preferably not create complementary regions that could hybridize to produce secondary mRNA structures, such as loops or hairpins, that would adversely affect translation of the mRNA. Although a mutation site may be predetermined, it is not necessary that the nature of the mutation per se be predetermined. For example, in order to select for optimum characteristics of mutants at a given site, random mutagenesis may be conducted at the target codon and the expressed mutants screened for indicative biological activity. Alternatively, mutations may be introduced at particular loci by synthesizing oligonucleotides containing a mutant sequence, flanked by restriction sites enabling ligation to fragments of the native sequence. Following ligation, the resulting reconstructed sequence encodes a derivative having the desired amino acid insertion, substitution, or deletion.

WRN proteins may also be constructed utilizing techniques of PCR mutagenesis, chemical mutagenesis (Drinkwater and Klinedinst, PNAS 83:3402-3406, 1986), by forced nucleotide misincorporation (e.g., Liao and Wise Gene 88:107-111, 1990), or by use of randomly mutagenized oligonucleotides (Horwitz et al., Genome 3:112-117, 1989).

Proteins can be isolated by, among other methods, culturing suitable host and vector systems to produce the recombinant translation products of the present invention. Supernates from such cell lines, or protein inclusions or whole cells where the protein is not excreted into the supernate, can then be treated by a variety of purification procedures in order to isolate the desired proteins. For example, the supernate may be first concentrated using commercially available protein concentration filters, such as an Amicon or Millipore Pellicon ultrafiltration unit. Following concentration, the concentrate may be applied to a suitable purification matrix such as, for example, an anti-protein antibody bound to a suitable support. Alternatively, anion or cation exchange resins may be employed in order to purify the protein. As a further alternative, one or more reverse-phase high performance liquid chromatography (RP-HPLC) steps may be employed to further purify the protein. Other methods of isolating the proteins of the present invention are well known in the skill of the art.

A protein is deemed to be "isolated" within the context of the present invention if no other (undesired) protein is detected pursuant to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis followed by Coomassie blue staining. Within other embodiments, the desired protein can be isolated such that no other (undesired) protein is detected pursuant to SDS-PAGE analysis followed by silver staining.

Expression of a WRN Gene

The present invention also provides for the manipulation and expression of the above described genes by culturing host cells containing a vector capable of expressing the above-described genes. Such vectors or vector constructs include either synthetic or cDNA-derived nucleic acid molecules encoding WRN proteins, which are operably linked to suitable transcriptional or translational regulatory elements. Suitable regulatory elements may be derived from a variety of sources, including bacterial, fungal, viral, mammalian, insect, or plant genes. Selection of appropriate regulatory elements is dependent on the host cell chosen, and may be readily accomplished by one of ordinary skill in the art. Examples of regulatory elements include: a transcriptional promoter and enhancer or RNA polymerase binding sequence, a transcriptional terminator, and a ribosomal binding sequence, including a translation initiation signal.

Nucleic acid molecules that encode any of the WRN proteins described above may be readily expressed by a wide variety of prokaryotic and eukaryotic host cells, including bacterial, mammalian, yeast or other fungi, viral, insect, or plant cells. Methods for transforming or transfecting such cells to express foreign DNA are well known in the art (see, e.g., Itakura et al., U.S. Pat. No. 4,704,362; Hinnen et al., Proc. Natl. Acad. Sci. USA 75:1929-1933, 1978; Murray et al., U.S. Pat. No. 4,801,542; Upshall et al., U.S. Pat. No. 4,935,349; Hagen et al., U.S. Pat. No. 4,784,950; Axel et al., U.S. Pat. No. 4,399,216; Goeddel et al., U.S. Pat. No. 4,766,075; and Sambrook et al. Molecular Cloning: A Laboratory Manual, 2nd edition, Cold Spring Harbor Laboratory Press, 1989; for plant cells see Czako and Marton, Plant Physiol. 104:1067-1071, 1994; and Paszkowski et al., Biotech. 24:387-392, 1992).

Bacterial host cells suitable for carrying out the present invention include E. coli, B. subtilis, Salmonella typhimurium, and various species within the genera Pseudomonas, Streptomyces, and Staphylococcus, as well as many other bacterial species well known to one of ordinary skill in the art. Representative examples of bacterial host cells include DH5.alpha. (Stratagene, LaJolla, Calif.).

Bacterial expression vectors preferably comprise a promoter which functions in the host cell, one or more selectable phenotypic markers, and a bacterial origin of replication. Representative promoters include the .beta.-lactamase (penicillinase) and lactose promoter system (see Chang et al., Nature 275:615, 1978), the T7 RNA polymerase promoter (Studier et al., Meth. Enzymol. 185:60-89, 1990), the lambda promoter (Elvin et al., Gene 87:123-126, 1990), the trp promoter (Nichols and Yanofsky, Meth. in Enzymology 101:155, 1983) and the tac promoter (Russell et al., Gene 20: 231, 1982). Representative selectable markers include various antibiotic resistance markers such as the kanamycin or ampicillin resistance genes. Many plasmids suitable for transforming host cells are well known in the art, including among others, pBR322 (see Bolivar et al., Gene 2:95, 1977), the pUC plasmids pUC18, pUC19, pUC118, pUC119 (see Messing, Meth. in Enzymology 101:20-77, 1983 and Vieira and Messing, Gene 19:259-268, 1982), and pNH8A, pNH16a, pNH18a, and Bluescript M13 (Stratagene, La Jolla, Calif.).

Yeast and fungi host cells suitable for carrying out the present invention include, among others, Saccharomyces pombe, Saccharomyces cerevisiae, the genera Pichia or Kluyveromyces and various species of the genus Aspergillus (McKnight et al., U.S. Pat. No. 4,935,349). Suitable expression vectors for yeast and fungi include, among others, YCp50 (ATCC No. 37419) for yeast, and the amdS cloning vector pV3 (Turnbull, Bio/Technology 7:169, 1989), YRp7 (Struhl et al., Proc. Natl. Acad. Sci. USA 76:1035-1039, 1978), YEp13 (Broach et al., Gene 8:121-133, 1979), pJDB249 and pJDB219 (Beggs, Nature 275:104-108, 1978) and derivatives thereof.

Preferred promoters for use in yeast include promoters from yeast glycolytic genes (Hitzeman et al., J. Biol. Chem. 255:12073-12080, 1980; Alber and Kawasaki, J. Mol. Appl. Genet. 1:419-434, 1982) or alcohol dehydrogenase genes (Young et al., in Genetic Engineering of Microorganisms for Chemicals, Hollaender et al. (eds.), p. 355, Plenum, New York, 1982; Ammerer, Meth. Enzymol. 101:192-201, 1983). Examples of useful promoters for fungi vectors include those derived from Aspergillus nidulans glycolytic genes, such as the adh3 promoter (McKnight et al., EMBO J. 4:2093-2099, 1985). The expression units may also include a transcriptional terminator. An example of a suitable terminator is the adh3 terminator (McKnight et al., ibid., 1985).

As with bacterial vectors, the yeast vectors will generally include a selectable marker, which may be one of any number of genes that exhibit a dominant phenotype for which a phenotypic assay exists to enable transformants to be selected. Preferred selectable markers are those that complement host cell auxotrophy, provide antibiotic resistance or enable a cell to utilize specific carbon sources, and include leu2 (Broach et al., ibid.), ura3 (Botstein et al., Gene 8:17, 1979), or his3 (Struhl et al., ibid.). Another suitable selectable marker is the cat gene, which confers chloramphenicol resistance on yeast cells.

Techniques for transforming fungi are well known in the literature, and have been described, for instance, by Beggs (ibid.), Hinnen et al. (Proc. Natl. Acad. Sci. USA 75:1929-1933, 1978), Yelton et al. (Proc. Natl. Acad. Sci. USA 81:1740-1747, 1984), and Russell (Nature 301:167-169, 1983). The genotype of the host cell may contain a genetic defect that is complemented by the selectable marker present on the expression vector. Choice of a particular host and selectable marker is well within the level of ordinary skill in the art.

Protocols for the transformation of yeast are also well known to those of ordinary skill in the art. For example, transformation may be readily accomplished either by preparation of spheroplasts of yeast with DNA (see Hinnen et al., PNAS USA 75:1929, 1978) or by treatment with alkaline salts such as LiCl (see Itoh et al., J. Bacteriology 153:163, 1983). Transformation of fungi may also be carried out using polyethylene glycol as described by Cullen et al. (Bio/Technology 5:369, 1987).

Viral vectors include those which comprise a promoter that directs the expression of an isolated nucleic acid molecule that encodes an WRN protein as described above. A wide variety of promoters may be utilized within the context of the present invention, including for example, promoters such as MoMLV LTR, RSV LTR, Friend MuLV LTR, adenoviral promoter (Ohno et al., Science 265: 781-784, 1994), neomycin phosphotransferase promoter/enhancer, late parvovirus promoter (Koering et al., Hum. Gene Therap. 5:457-463, 1994), Herpes TK promoter, SV40 promoter, metallothionein IIa gene enhancer/promoter, cytomegalovirus immediate early promoter, and the cytomegalovirus immediate late promoter. Within particularly preferred embodiments of the invention, the promoter is a tissue-specific promoter (see e.g., WO 91/02805; EP 0,415,731; and WO 90/07936). Representative examples of suitable tissue specific promoters include neural specific enolase promoter, platelet derived growth factor beta promoter, bone morpho-genetic protein promoter, human alpha1-chimaerin promoter, synapsin I promoter and synapsin II promoter. In addition to the above-noted promoters, other viral-specific promoters (e.g., retroviral promoters (including those noted above, as well as others such as HIV promoters), hepatitis, herpes (e.g., EBV), and bacterial, fungal or parasitic (e.g., malarial)-specific promoters may be utilized in order to target a specific cell or tissue which is infected with a virus, bacteria, fungus or parasite.

Thus, WRN proteins of the present invention may be expressed from a variety of viral vectors, including for example, herpes viral vectors (e.g., U.S. Pat. No. 5,288,641), adenoviral vectors (e.g., WO 94/26914, WO 93/9191; Kolls et al., PNAS 91(1):215-219, 1994; Kass-Eisler et al., PNAS 90(24):11498-502, 1993; Guzman et al., Circulation 88(6):2838-48, 1993; Guzman et al., Cir. Res. 73(6):1202-1207, 1993; Zabner et al., Cell 75(2):207-216, 1993; Li et al., Hum Gene Ther. 4(4):403-409, 1993; Caillaud et al., Eur. J. Neurosci. 5(10:1287-1291, 1993; Vincent et al., Nat. Genet. 5(2):130-134, 1993; Jaffe et al., Nat. Genet. 1(5):372-378, 1992; and Levrero et al, Gene 101(2):195-202, 1991), adeno-associated viral vectors (WO 95/13365; Flotte et al., PNAS 90(22):10613-10617, 1993), baculovirus vectors, parvovirus vectors (Koering et al., Hum. Gene Therap. 5:457-463, 1994), pox virus vectors (Panicali and Paoletti, PNAS 79:4927-4931, 1982; and Ozaki et al., Biochem. Biophys. Res. Comm. 193(2):653-660, 1993), and retroviruses (e.g., EP 0,415,731; WO 90/07936; WO 91/0285, WO 94/03622; WO 93/25698; WO 93/25234; U.S. Pat. No. 5,219,740; WO 93/11230; WO 93/10218. Viral vectors may likewise be constructed which contain a mixture of different elements (e.g., promoters, envelope sequences and the like) from different viruses, or non-viral sources. Within various embodiments, either the viral vector itself, or a viral particle which contains the viral vector may be utilized in the methods and compositions described below.

Mammalian cells suitable for carrying out the present invention include, among others: PC12 (ATCC No. CRL1721), NIE-115 neuroblastoma, SK-N-BE(2)C neuroblastoma, SHSY5 adrenergic neuroblastoma, NS20Y and NG108-15 murine cholinergic cell lines, or rat F2 dorsal root ganglion line, COS (e.g., ATCC No. CRL 1650 or 1651), BHK (e.g., ATCC No. CRL 6281; BHK 570 cell line (deposited with the American Type Culture Collection under accession number CRL 10314), CHO (ATCC No. CCL 61), HeLa (e.g., ATCC No. CCL 2), 293 (ATCC No. 1573; Graham et al., J. Gen. Virol. 36:59-72, 1977) and NS-1 cells. Other mammalian cell lines may be used within the present invention, including Rat Hep I (ATCC No. CRL 1600), Rat Hep II (ATCC No. CRL 1548), TCMK (ATCC No. CCL 139), Human lung (ATCC No. CCL 75.1), Human hepatoma (ATCC No. HTB-52), Hep G2 (ATCC No. HB 8065), Mouse liver (ATCC No. CCL 29.1), NCTC 1469 (ATCC No. CCL 9.1), SP2/0-Ag14 (ATCC No. 1581), HIT-T15 (ATCC No. CRL 1777), and RINm 5AHT.sub.2B (Orskov and Nielson, FEBS 229(1):175-178, 1988).

Mammalian expression vectors for use in carrying out the present invention will include a promoter capable of directing the transcription of a cloned gene or cDNA. Preferred promoters include viral promoters and cellular promoters. Viral promoters include the cytomegalovirus immediate early promoter (Boshart et al., Cell 41:521-530, 1985), cytomegalovirus immediate late promoter, SV40 promoter (Subramani et al., Mol. Cell. Biol. 1:854-864, 1981), MMTV LTR, RSV LTR, metallothionein-1, adenovirus E1a. Cellular promoters include the mouse metallothionein-1 promoter (Palmiter et al., U.S. Pat. No. 4,579,821), a mouse V.sub..kappa. promoter (Bergman et al., Proc. Natl. Acad. Sci. USA 81:7041-7045, 1983; Grant et al., Nucl. Acids Res. 15:5496, 1987) and a mouse V.sub.H promoter (Loh et al., Cell 33:85-93, 1983). The choice of promoter will depend, at least in part, upon the level of expression desired or the recipient cell line to be transfected.

Such expression vectors may also contain a set of RNA splice sites located downstream from the promoter and upstream from the DNA sequence encoding the peptide or protein of interest. Preferred RNA splice sites may be obtained from adenovirus and/or immunoglobulin genes. Also contained in the expression vectors is a polyadenylation signal located downstream of the coding sequence of interest. Suitable polyadenylation signals include the early or late polyadenylation signals from SV40 (Kaufman and Sharp, ibid.), the polyadenylation signal from the Adenovirus 5 E1B region and the human growth hormone gene terminator (DeNoto et al., Nuc. Acids Res. 9:3719-3730, 1981). The expression vectors may include a noncoding viral leader sequence, such as the Adenovirus 2 tripartite leader, located between the promoter and the RNA splice sites. Preferred vectors may also include enhancer sequences, such as the SV40 enhancer. Expression vectors may also include sequences encoding the adenovirus VA RNAs. Suitable expression vectors can be obtained from commercial sources (e.g., Stratagene, La Jolla, Calif.).

Vector constructs comprising cloned DNA sequences can be introduced into cultured mammalian cells by, for example, calcium phosphate-mediated transfection (Wigler et al., Cell 14:725, 1978; Corsaro and Pearson, Somatic Cell Genetics 7:603, 1981; Graham and Van der Eb, Virology 52:456, 1973), electroporation (Neumann et al., EMBO J. 1:841-845, 1982), or DEAE-dextran mediated transfection (Ausubel et al. (eds.), Current Protocols in Molecular Biology, John Wiley and Sons, Inc., NY, 1987). To identify cells that have stably integrated the cloned DNA, a selectable marker is generally introduced into the cells along with the gene or cDNA of interest. Preferred selectable markers for use in cultured mammalian cells include genes that confer resistance to drugs, such as neomycin, hygromycin, and methotrexate. The selectable marker may be an amplifiable selectable marker. Preferred amplifiable selectable markers are the DHFR gene and the neomycin resistance gene. Selectable markers are reviewed by Thilly (Mammalian Cell Technology, Butterworth Publishers, Stoneham, Mass., which is incorporated herein by reference).

Mammalian cells containing a suitable vector are allowed to grow for a period of time, typically 1-2 days, to begin expressing the DNA sequence(s) of interest. Drug selection is then applied to select for growth of cells that are expressing the selectable marker in a stable fashion. For cells that have been transfected with an amplifiable, selectable marker the drug concentration may be increased in a stepwise manner to select for increased copy number of the cloned sequences, thereby increasing expression levels. Cells expressing the introduced sequences are selected and screened for production of the protein of interest in the desired form or at the desired level. Cells that satisfy these criteria can then be cloned and scaled up for production.

Protocols for the transfection of mammalian cells are well known to those of ordinary skill in the art. Representative methods include calcium phosphate mediated transfection, electroporation, lipofection, retroviral, adenoviral and protoplast fusion-mediated transfection (see Sambrook et al., supra). Naked vector constructs can also be taken up by muscular cells or other suitable cells subsequent to injection into the muscle of a mammal (or other animals).

Numerous insect host cells known in the art can also be useful within the present invention, in light of the subject specification. For example, the use of baculoviruses as vectors for expressing heterologous DNA sequences in insect cells has been reviewed by Atkinson et al. (Pestic. Sci. 28:215-224,1990).

Numerous plant host cells known in the art can also be useful within the present invention, in light of the subject specification. For example, the use of Agrobacterium rhizogenes as vectors for expressing genes in plant cells has been reviewed by Sinkar et al., (J. Biosci. (Bangalore) 11:47-58, 1987).

WRN proteins may be prepared by growing (typically by culturing) the host/vector systems described above, in order to express the recombinant WRN proteins. Recombinantly produced WRN proteins may be further purified as described in more detail below.

Within related aspects of the present invention, WRN proteins may be expressed in a transgenic animal whose germ cells and somatic cells contain a WRN gene which is operably linked to a promoter effective for the expression of the gene. Alternatively, in a similar manner transgenic animals may be prepared that lack the WRN gene (e.g., "knockout" mice). Such transgenics may be prepared in a variety non-human animals, including mice, rats, rabbits, sheep, dogs, goats and pigs (see Hammer et al. Nature 315:680-683, 1985, Palmiter et al. Science 222:809-814, 1983, Brinster et al. Proc. Natl. Acad. Sci. USA 82:4438-4442, 1985, Palmiter and Brinster Cell 41:343-345, 1985 and U.S. Pat. Nos. 5,175,383, 5,087,571, 4,736,866, 5,387,742, 5,347,075, 5,221,778, and 5,175,384).

Briefly, an expression vector, including a nucleic acid molecule to be expressed together with appropriately positioned expression control sequences, is introduced into pronucleli of fertilized eggs, for example, by microinjection. Integration of the injected DNA is detected by blot analysis of DNA from tissue samples. It is preferred that the introduced DNA be incorporated into the germ line of the animal so that it is passed on to the animal's progeny. Tissue-specific expression may be achieved through the use of a tissue-specific promoter, or through the use of an inducible promoter, such as the metallothionein gene promoter (Palmiter et al., 1983, ibid), which allows regulated expression of the transgene.

Vectors of the present invention may contain or express a wide variety of additional nucleic acid molecules in place of or in addition to an WRN protein as described above, either from one or several separate promoters. For example, the viral vector may express a lymphokine or lymphokine receptor, antisense or ribozyme sequence or toxins. Representative examples of lymphokines include IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-11, IL-12, IL-13, IL-14, IL-15, GM-CSF, G-CSF, M-CSF, alpha-interferon, beta-interferon, gamma-interferon, and tumor necrosis factors, as well as their respective receptors. Representative examples of antisense sequences include antisense sequences which block the expression of WRN protein mutants. Representative examples of toxins include: ricin, abrin, diphtheria toxin, cholera toxin, saporin, gelonin, pokeweed antiviral protein, tritin, Shigella toxin, and Pseudomonas exotoxin A.

Within other aspects of the invention, antisense oligonucleotide molecules are provided which specifically inhibit expression of mutant WRN nucleic acid sequences (see generally, Hirashima et al. in Molecular Biology of RNA: New Perspectives (M. Inouye and B. S. Dudock, eds., 1987 Academic Press, San Diego, p. 401); Oligonucleotides: Antisense Inhibitors of Gene Expression (J. S. Cohen, ed., 1989 MacMillan Press, London); Stein and Cheng, Science 261:1004-1012 (1993); WO 95/10607; U.S. Pat. No. 5,359,051; WO 92/06693; and EP-A2-612844). Briefly, such molecules are constructed such that they are complementary to, and able to form Watson-Crick base pairs with, a region of transcribed WRN mutant mRNA sequence containing an WRN mutation. The resultant double-stranded nucleic acid interferes with subsequent processing of the mRNA, thereby preventing protein synthesis.

Within other related aspects of the invention, ribozyme molecules are provided wherein an antisense oligonucleotide sequence is incorporated into a ribozyme which can specifically cleave mRNA molecules transcribed from a mutant WRN gene (see generally, Kim et al. Proc. Nat. Acad. Sci. USA 84:8788 (1987); Haseloff, et al. Nature 234:585 (1988), Cech, JAMA 260:3030 (1988); Jeffries, et al. Nucleic Acids Res. 17:1371 (1989); U.S. Pat. Nos. 5,093,246; 5,354,855; 5,144,019; 5,272,262; 5,254,678; and 4,987,071). According to this aspect of the invention, the antisense sequence which is incorporated into a ribozyme includes a sequence complementary to, and able to form Watson-Crick base pairs with, a region of the transcribed mutant WRN mRNA containing an WRN mutation. The antisense sequence thus becomes a targeting agent for delivery of catalytic ribozyme activity specifically to mutant WRN mRNA, where such catalytic activity cleaves the mRNA to render it incapable of being subsequently processed for WRN protein translation.

Host Cells

As discussed above, nucleic acid molecules which encode the WRN proteins of the present invention (or the vectors which contain and/or express related mutants) may readily be introduced into a wide variety of host cells. Representative examples of such host cells include plant cells, eukaryotic cells, and prokaryotic cells. Within preferred embodiments, the nucleic acid molecules are introduced into cells from a vertebrate or warm-blooded animal, such as a human, macaque, dog, cow, horse, pig, sheep, rat, hamster, mouse or fish cell, or any hybrid thereof.

Preferred prokaryotic host cells for use within the present invention include E. coli, Salmonella, Bacillus, Shigella, Pseudomonas, Streptomyces and other genera. Techniques for transforming these hosts and expressing foreign DNA sequences cloned therein are well known in the art (see, e.g., Maniatis et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, 1982, which is incorporated herein by reference; or Sambrook et al., supra). Vectors used for expressing cloned DNA sequences in bacterial hosts will generally contain a selectable marker, such as a gene for antibiotic resistance, and a promoter that functions in the host cell. Appropriate promoters include the trp (Nichols and Yanofsky, Meth. Enzymol. 101:155-164, 1983), lac (Casadaban et al., J. Bacteriol. 143:971-980, 1980), and phage .lamda. (Queen, J. Mol. Appl. Genet. 2:1-10, 1983) promoter systems. Plasmids useful for transforming bacteria include the pUC plasmids (Messing, Meth. Enzymol. 101:20-78, 1983; Vieira and Messing, Gene 19:259-268, 1982), pBR322 (Bolivar et al., Gene 2:95-113, 1977), pCQV2 (Queen, ibid.), and derivatives thereof. Plasmids may contain both viral and bacterial elements.

Preferred eukaryotic cells include cultured mammalian cell lines (e.g., rodent or human cell lines) and fungal cells, including species of yeast (e.g., Saccharomyces spp., particularly S. cerevisiae, Schizosaccharomyces spp., or Kluyveromyces spp.) or filamentous fungi (e.g., Aspergillus spp., Neurospora spp.). Strains of the yeast Saccharomyces cerevisiae are particularly preferred. Methods for producing recombinant proteins in a variety of prokaryotic and eukaryotic host cells are generally known in the art (see, "Gene Expression Technology," Methods in Enzymology, Vol. 185, Goeddel (ed.), Academic Press, San Diego, Calif., 1990; see also, "Guide to Yeast Genetics and Molecular Biology," Methods in Enzymology, Guthrie and Fink (eds.), Academic Press, San Diego, Calif., 1991). In general, a host cell will be selected on the basis of its ability to produce the protein of interest at a high level or its ability to carry out at least some of the processing steps necessary for the biological activity of the protein. In this way, the number of cloned DNA sequences that must be introduced into the host cell can be minimized and overall yield of biologically active protein can be maximized.

The nucleic acid molecules (or vectors) may be introduced into host cells by a wide variety of mechanisms, including for example calcium phosphate-mediated transfection (Wigler et al., Cell 14:725, 1978), lipofection; gene gun (Corsaro and Pearson, Somatic Cell Gen. 7:603, 1981; Graham and Van der Eb, Virology 52:456, 1973), electroporation (Neumann et al., EMBO J. 1:841-845, 1982), retroviral, adenoviral, protoplast fusion-mediated transfection or DEAE-dextran mediated transfection (Ausubel et al., (eds.), Current Protocols in Molecular Biology, John Wiley and Sons, Inc., NY, N.Y., 1987).

Host cells containing vector constructs of the present invention are then cultured to express a DNA molecule as described above. The cells are cultured according to standard methods in a culture medium containing nutrients required for growth of the chosen host cells. A variety of suitable media are known in the art and generally include a carbon source, a nitrogen source, essential amino acids, vitamins and minerals, as well as other components, e.g., growth factors or serum, that may be required by the particular host cells. The growth medium will generally select for cells containing the DNA construct(s) by, for example, drug selection or deficiency in an essential nutrient which is complemented by the selectable marker on the DNA construct or co-transfected with the DNA construct.

Suitable growth conditions for yeast cells, for example, include culturing in a chemically defined medium, comprising a nitrogen source, which may be a non-amino acid nitrogen source or a yeast extract, inorganic salts, vitamins and essential amino acid supplements at a temperature between 4.degree. C. and 37.degree. C., with 30.degree. C. being particularly preferred. The pH of the medium is preferably maintained at a pH greater than 2 and less than 8, more preferably pH 5-6. Methods for maintaining a stable pH include buffering and constant pH control. Preferred agents for pH control include sodium hydroxide. Preferred buffering agents include succinic acid and Bis-Tris (Sigma Chemical Co., St. Louis, Mo.). Due to the tendency of yeast host cells to hyperglycosylate heterologous proteins, it may be preferable to express the nucleic acid molecules of the present invention in yeast cells having a defect in a gene required for asparagine-linked glycosylation. Such cells are preferably grown in a medium containing an osmotic stabilizer. A preferred osmotic stabilizer is sorbitol supplemented into the medium at a concentration between 0.1 M and 1.5 M, preferably at 0.5 M or 1.0 M.

Cultured mammalian cells are generally cultured in commercially available serum-containing or serum-free media. Selection of a medium and growth conditions appropriate for the particular cell line used is well within the level of ordinary skill in the art.

Antibodies

Antibodies to the WRN proteins discussed above may readily be prepared given the disclosure provided herein. Such antibodies may, within certain embodiments, specifically recognize wild type WRN protein rather than a mutant WRN protein, mutant WRN protein rather than wild type WRN protein, or equally recognize both the mutant and wild-type forms of WRN protein. Antibodies may be used for isolation of the protein, establishing intracellular localization of the WRN protein, inhibiting activity of the protein (antagonist), or enhancing activity of the protein (agonist). Knowledge of the intracellular location of the WRN gene product may be abnormal in patients with WRN mutations, thus allowing the development of a rapid screening assay. As well, assays for small molecules that interact with the WRN gene product will be facilitated by the development of antibodies and localization studies.

Within the context of the present invention, antibodies are understood to include monoclonal antibodies, polyclonal antibodies, anti-idiotypic antibodies, antibody fragments (e.g., Fab, and F(ab').sub.2, F.sub.v variable regions, or complementarity determining regions). As discussed above, antibodies are understood to be specific against an WRN protein if it binds with a K.sub.d of greater than or equal to 10.sup.-7M, preferably greater than of equal to 10.sup.-8M. The affinity of a monoclonal antibody or binding partner can be readily determined by one of ordinary skill in the art (see Scatchard, Ann. N.Y. Acad. Sci. 51:660-672, 1949).

Briefly, polyclonal antibodies may be readily generated by one of ordinary skill in the art from a variety of warm-blooded animals such as horses, cows, various fowl, rabbits, mice, or rats. Typically, an WRN protein or unique peptide thereof of 13-20 amino acids (preferably conjugated to keyhole limpet hemocyanin by cross-linking with glutaraldehyde) is utilized to immunize the animal through intraperitoneal, intramuscular, intraocular, or subcutaneous injections, an adjuvant such as Freund's complete or incomplete adjuvant. Merely as an example, a peptide corresponding to residues 1375 through 1387 of the WRN polypeptide sequence is used to raise a rabbit polyclonal antiserum. Following several booster immunizations, samples of serum are collected and tested for reactivity to the WRN protein or peptide. Particularly preferred polyclonal antisera will give a signal on one of these assays that is at least three times greater than background. Once the titer of the animal has reached a plateau in terms of its reactivity to the protein, larger quantities of antisera may be readily obtained either by weekly bleedings, or by exsanguinating the animal.

Monoclonal antibodies may also be readily generated using conventional techniques (see U.S. Pat. Nos. RE 32,011, 4,902,614, 4,543,439, and 4,411,993 which are incorporated herein by reference; see also Monoclonal Antibodies, Hybridomas: A New Dimension in Biological Analyses, Plenum Press, Kennett, McKearn, and Bechtol (eds.), 1980, and Antibodies: A Laboratory Manual, Harlow and Lane (eds.), Cold Spring Harbor Laboratory Press, 1988, which are also incorporated herein by reference).

Briefly, within one embodiment a subject animal such as a rat or mouse is injected with an WRN protein or portion thereof as described above. The protein may be admixed with an adjuvant such as Freund's complete or incomplete adjuvant in order to increase the resultant immune response. Between one and three weeks after the initial immunization the animal may be reimmunized with another booster immunization, and tested for reactivity to the protein utilizing assays described above. Once the animal has reached a plateau in its reactivity to the injected protein, it is sacrificed, and organs which contain large numbers of B cells such as the spleen and lymph nodes are harvested.

Cells which are obtained from the immunized animal may be immortalized by transfection with a virus such as the Epstein-Barr virus (EBV) (see Glasky and Reading, Hybridoma 8(4):377-389, 1989). Alternatively, within a preferred embodiment, the harvested spleen and/or lymph node cell suspensions are fused with a suitable myeloma cell in order to create a "hybridoma" which secretes monoclonal antibody. Suitable myeloma lines include, for example, NS-1 (ATCC No. TIB 18), and P3.times.63-Ag 8.653 (ATCC No. CRL 1580).

Following the fusion, the cells may be placed into culture plates containing a suitable medium, such as RPMI 1640, or DMEM (Dulbecco's Modified Eagles Medium) (JRH Biosciences, Lenexa, Kans.), as well as additional ingredients, such as fetal bovine serum (FBS, i.e., from Hyclone, Logan, Utah, or JRH Biosciences). Additionally, the medium should contain a reagent which selectively allows for the growth of fused spleen and myeloma cells such as HAT (hypoxanthine, aminopterin, and thymidine) (Sigma Chemical Co., St. Louis, Mo.). After about seven days, the resulting fused cells or hybridomas may be screened in order to determine the presence of antibodies which are reactive against an WRN protein. A wide variety of assays may be utilized to determine the presence of antibodies which are reactive against the proteins of the present invention, including for example countercurrent immuno-electrophoresis, radioimmunoassays, radioimmunoprecipitations, enzyme-linked immuno-sorbent assays (ELISA), dot blot assays, western blots, immunoprecipitation, Inhibition or Competition Assays, and sandwich assays (see U.S. Pat. Nos. 4,376,110 and 4,486,530; see also Antibodies: A Laboratory Manual, Harlow and Lane (eds.), Cold Spring Harbor Laboratory Press, 1988). Following several clonal dilutions and reassays, a hybridoma producing antibodies reactive against the WRN protein may be isolated.

Other techniques may also be utilized to construct monoclonal antibodies (see William D. Huse et al., "Generation of a Large Combinational Library of the Immunoglobulin Repertoire in Phage Lambda," Science 246:1275-1281, December 1989; see also L. Sastry et al., "Cloning of the Immunological Repertoire in Escherichia coli for Generation of Monoclonal Catalytic Antibodies: Construction of a Heavy Chain Variable Region-Specific cDNA Library," Proc. Natl. Acad. Sci. USA 86:5728-5732, August 1989; see also Michelle Alting-Mees et al., "Monoclonal Antibody Expression Libraries: A Rapid Alternative to Hybridomas," Strategies in Molecular Biology 3:1-9, January 1990; these references describe a commercial system available from Stratacyte, La Jolla, Calif., which enables the production of antibodies through recombinant techniques). Briefly, mRNA is isolated from a B cell population, and utilized to create heavy and light chain immunoglobulin cDNA expression libraries in the .lamda.ImmunoZap(H) and .lamda.ImmunoZap(L) vectors. These vectors may be screened individually or co-expressed to form Fab fragments or antibodies (see Huse et al., supra; see also Sastry et al., supra). Positive plaques may subsequently be converted to a non-lytic plasmid which allows high level expression of monoclonal antibody fragments from E. coli.

Similarly, portions or fragments, such as Fab and Fv fragments, of antibodies may also be constructed utilizing conventional enzymatic digestion or recombinant DNA techniques to incorporate the variable regions of a gene which encodes a specifically binding antibody. Within one embodiment, the genes which encode the variable region from a hybridoma producing a monoclonal antibody of interest are amplified using nucleotide primers for the variable region. These primers may be synthesized by one of ordinary skill in the art, or may be purchased from commercially available sources. Stratacyte (La Jolla, Calif.) sells primers for mouse and human variable regions including, among others, primers for V.sub.Ha, V.sub.Hb, V.sub.Hc, V.sub.Hd, C.sub.H1, V.sub.L and C.sub.Lregions. These primers may be utilized to amplify heavy or light chain variable regions, which may then be inserted into vectors such as ImmunoZAP.TM. H or ImmunoZAP.TM. L (Stratacyte), respectively. These vectors may then be introduced into E. coli, yeast, or mammalian-based systems for expression. Utilizing these techniques, large amounts of a single-chain protein containing a fusion of the V.sub.H and V.sub.L domains may be produced (see Bird et al., Science 242:423-426, 1988). In addition, such techniques may be utilized to change a "murine" antibody to a "human" antibody, without altering the binding specificity of the antibody.

Once suitable antibodies have been obtained, they may be isolated or purified by many techniques well known to those of ordinary skill in the art (see Antibodies: A Laboratory Manual, Harlow and Lane (eds.), Cold Spring Harbor Laboratory Press, 1988). Suitable techniques include peptide or protein affinity columns, HPLC or RP-HPLC, purification on protein A or protein G columns, or any combination of these techniques.

Assays

Assays useful within the context of the present invention include those assays for detecting agonists or antagonists of WRN protein activity. Other assays are useful for the screening of peptide or organic molecule libraries. Still other assays are useful for the identification and/or isolation of nucleic acid molecules and/or peptides within the present invention, the identification of proteins that interact or bind the WRN protein, for diagnosis of a patient with an increased likelihood of contracting Werner's Syndrome, or for diagnosis of a patient with susceptibility to or manifestation of a WRN-related disease.

Nucleic Acid Based Diagnostic Tests

Briefly, another aspect of the present invention provides probes and primers for detecting the WRN genes and/or mutants thereof. In one embodiment of this aspect, probes are provided that are capable of specifically hybridizing to DNA or RNA of the WRN genes. For purposes of the present invention, probes are "capable of hybridizing" to DNA or RNA of the WRN gene if they hybridize to an WRN gene under conditions of either high or moderate stringency (see Sambrook et al., supra) but not significantly or detectably to the an unrelated helicase gene such as the Bloom's Syndrome gene (Ellis et al., Cell 83:655-666, 1995). Preferably, the probe hybridizes to suitable nucleotide sequences under high stringency conditions, such as hybridization in 5.times.SSPE, 1.times. Denhardt's solution, 0.1% SDS at 65.degree. C., and at least one wash to remove unhybridized probe in the presence of 0.2.times.SSC, 1.times. Denhardt's solution, 0.1% SDS at 65.degree. C. Except as otherwise provided herein, probe sequences are designed to allow hybridization to WRN genes, but not to DNA or RNA sequences from other genes. The probes are used, for example, to hybridize to nucleic acid that is present in a biological sample isolated from a patient. The hybridized probe is then detected, thereby indicating the presence of the desired cellular nucleic acid. Preferably, the cellular nucleic acid is subjected to an amplification procedure, such as PCR, prior to hybridization. Alternatively, the WRN gene may be amplified and the amplified product subjected to DNA sequencing. Mutants of WRN may be detected by DNA sequence analysis or hybridization with allele-specific oligonucleotide probes under conditions and for time sufficient to allow hybridization to the specific allele. Typically, the hybridization buffer and wash will contain tetramethyl ammonium chloride or the like (see Sambrook et al., supra).

Nucleic acid probes of the present invention may be composed of either deoxyribonucleic acids (DNA), ribonucleic acids (RNA), nucleic acid analogues (e.g., peptide nucleic acids), or any combination thereof, and may be as few as about 12 nucleotides in length, usually about 14 to 18 nucleotides in length, and possibly as large as the entire sequence of a WRN gene. Selection of probe size is somewhat dependent upon the use of the probe, and is within the skill of the art.

Suitable probes can be constructed and labeled using techniques that are well known in the art. Shorter probes of, for example, 12 bases can be generated synthetically and labeled with .sup.32P using T.sub.4 polynucleotide kinase. Longer probes of about 75 bases to less than 1.5 kb are preferably generated by, for example, PCR amplification in the presence of labeled precursors such as [.alpha.-.sup.32P]dCTP, digoxigenin-dUTP, or biotin-dATP. Probes of more than 1.5 kb are generally most easily amplified by transfecting a cell with a plasmid containing the relevant probe, growing the transfected cell into large quantities, and purifying the relevant sequence from the transfected cells. (See Sambrook et al., supra.)

Probes can be labeled by a variety of markers, including for example, radioactive markers, fluorescent markers, enzymatic markers, and chromogenic markers. The use of .sup.32P is particularly preferred for marking or labeling a particular probe.

It is a feature of this aspect of the invention that the probes can be utilized to detect the presence of WRN mRNA or DNA within a sample. However, if the relevant sample is present in only a limited number, then it may be beneficial to amplify the relevant sequence so that it may be more readily detected or obtained.

A variety of methods may be utilized in order to amplify a selected sequence, including, for example, RNA amplification (see Lizardi et al., Bio/Technology 6:1197-1202, 1988; Kramer et al., Nature 339:401-402, 1989; Lomeli et al., Clinical Chem. 35(9):1826-1831, 1989; U.S. Pat. No. 4,786,600), and DNA amplification utilizing LCR or polymerase chain reaction ("PCR") (see, U.S. Pat. Nos. 4,683,195, 4,683,202, and 4,800,159) (see also U.S. Pat. Nos. 4,876,187 and 5,011,769, which describe an alternative detection/amplification system comprising the use of scissile linkages), or other nucleic acid amplification procedures that are well within the level of ordinary skill in the art. With respect to PCR, for example, the method may be modified as known in the art. Transcriptional enhancement of PCR may be accomplished by incorporation of bacteriophage T7 RNA polymerase promoter sequences in one of the primary oligonucleotides, and immunoenzymatic detection of the products from the enhanced emitter may be effected using anti-RNA:DNA antibodies (Blais, Appl. Environ. Microbiol. 60:348-352, 1994). PCR may also be used in combination with reverse dot-blot hybridization (Iida et al., FEMS Microbiol. Lett. 114:167-172, 1993). PCR products may be quantitatively analyzed by incorporation of dUTP (Duplaa et al., Anal. Biochem. 212:229-236, 1993), and samples may be filter sampled for PCR-gene probe detection (Bej et al., Appl. Environ. Microbiol. 57:3529-3534, 1991).

Within a particularly preferred embodiment, PCR amplification is utilized to detect the WRN DNA. Briefly, as described in greater detail below, a DNA sample is denatured at 95.degree. C. in order to generate single-stranded DNA. The DNA sample may be a cDNA generated from RNA. Specific primers are then annealed to the single-stranded DNA at 37.degree. C. to 70.degree. C., depending on the proportion of AT/GC in the primers. The primers are extended at 72.degree. C. with Taq DNA polymerase or other thermostable DNA polymerase in order to generate the opposite strand to the template. These steps constitute one cycle, which may be repeated in order to amplify the selected sequence. For greater specificity, nested PCR may be performed. In nested PCR, a second amplification is performed using a second set of primers derived from sequences within the first amplified product. The entire coding region of WRN may be amplified from cDNA using three sets of primers to generate fragment lengths that are a convenient size for determining their sequence. In a preferred embodiment, nested PCR is performed.

Within an alternative preferred embodiment, LCR amplification is utilized for amplification. LCR primers are synthesized such that the 5' base of the upstream primer is capable of hybridizing to a unique base pair in a desired gene to specifically detect an WRN gene.

Within another preferred embodiment, the probes are used in an automated, non-isotopic strategy wherein target nucleic acid sequences are amplified by PCR, and then desired products are determined by a calorimetric oligonucleotide ligation assay (OLA) (Nickerson et al., Proc. Natl. Acad. Sci. USA 81:8923-8927, 1990).

Primers for the amplification of a selected sequence should be selected from sequences that are highly specific to WRN (and not, e.g., the Bloom's Syndrome gene, supra) and form stable duplexes with the target sequence. The primers should also be non-complementary, especially at the 3' end, should not form dimers with themselves or other primers, and should not form secondary structures or duplexes with other regions of DNA. In general, primers of about 18 to 20 nucleotides are preferred, and can be easily synthesized using techniques well known in the art. PCR products, and other nucleic acid amplification products, may be quantitated using techniques known in the art (Duplaa et al., Anal. Biochem. 212:229-236, 1993; Higuchi et al., Bio/Technology 11:1026-1030).

Within one embodiment of the invention, nucleic acid diagnostics may be developed which are capable of detecting the presence of Werner's Syndrome, or of various related diseases that may be caused by Werner's Syndrome. Briefly, severe mutations in the WRN gene may lead to Werner's Syndrome, as well as a host of related diseases, including for example, increased frequency of some benign and malignant neoplasms (especially sarcomas), cataracts, cardiovascular disease, osteoporosis, type I or type II diabetes, cataracts, sclerodoma-like skin changes and hyperkeratosis. Less severe mutations of the gene may lead to the onset of the same set of diseases, but at an older age. In addition, many of the related diseases may be associated with mutations in the WRN gene. For example, diabetes and osteoporosis are often associated with aging. Aging population and individuals with these (or other) diseases are screened for mutations in WRN. Any of the assays described herein may be used. RT-PCR is especially preferred in conjunction with DNA sequence determination. To correlate a mutation or polymorphism with disease, sibling pairs in which one sibling has disease are preferred subjects. Once a mutation is identified, other convenient screening assays may be used to assay particular nucleotide changes.

Since the sequences of the two copies of the gene from non-Werner's affected individuals can be correlated with the medical histories of these patients to define these correspondences, these alleles can therefore be used as diagnostics for susceptibilities to these diseases, once the relationship is defined. Certain non-null forms of the gene, for example, in either the homozygous or heterozygous state may significantly affect the propensity for the carriers to develop, for example, cancer. These propensities can be ascertained by examining the sequences of the gene (both copies) in a statistically significant sample of cancer patients. Other diseases (see above) can be similarly examined for significant correlations with certain alleles. To detect such a causal relationship one can use a chi-squared test, or other statistical test, to examine the significance of any correlation between the appropriate genotypes and the disease state as recorded in the medical records, using standard good practices of medical epidemiology. The sequences that define each of the alleles are then valuable diagnostic indicators for an increased susceptibility to the disease. Thus, from the nucleic acid sequences provided herein, a wide variety of Werner's Syndrome-related diseases may be readily detected.

Another cellular phenotype of the cells from Werner's patients is the increased frequency of deletion mutation in these cells. Clearly, the defective helicase in these cells leads to a specific mutator phenotype, while not rendering the cells hypersensitive to a variety of chemical or physical mutagens that damage DNA, like ionizing radiation. Disease states, or sensitivities that result from an elevated deletion frequency can therefore be controlled, in part, by alterations of the Werner's gene, and some alleles may therefore be diagnostic of this class of medical conditions.

Assays for Agonists and Antagonists

An agonist or antagonist of the WRN gene product comprising a protein, peptide, chemical, or peptidomimetic that binds to the WRN gene product or interacts with a protein that binds to the WRN gene product such that the binding of the agonist or antagonist affects the activity of the WRN gene product. An agonist will activate or increase the activity of the WRN gene product. An antagonist will inhibit or decrease the activity of the WRN gene product. The activity of the WRN gene product may be measured in an assay, such as a helicase assay or other assay that measures an activity of the WRN gene product. Other assays measure the binding of protein that interacts with WRN and is necessary for its activity.

Agonists and antagonists of the WRN gene product may be used to enhance activity or inhibit activity of the gene product. Such agonists and antagonists may be identified in a variety of methods. For example, proteins that bind and activate WRN may be identified using a yeast 2-hybrid detection system. In this system, the WRN gene is fused to either a DNA-binding domain or an activating domain of a yeast gene such as GAL4. A cDNA library is constructed in a vector such that the inserts are fused to one of the domains. The vectors are co-transfected into yeast and selected for transcriptional activation of a reporter gene (Fields and Song, Nature 340: 245, 1989). The protein(s) that bind to WRN are candidate agonists. Three different proteins that bind WRN have been identified in an initial screen using the 2-hybrid system.

When the binding site on WRN gene product is determined, molecules that bind and activate WRN protein may be designed and evaluated. For example, computer modeling of the binding site can be generated and mimetics that bind can be designed. Antibodies to the binding site may be generated and analogues of native binding proteins generated as well. Any of these molecules is tested for agonist or antagonist activity by a functional assay of the WRN gene product. For example, to test for antagonist activity, yeast are co-transfected with the WRN and binding protein each fused to a DNA binding domain or an activation domain. The test molecule is administered and activation is monitored. An antagonist will inhibit the activation of the reporter gene by at least 50%. Similarly, agonist activity may be measured by either enhancing WRN activity in a yeast 2-hybrid system or by coupling the test compound to a DNA binding or activation domain and monitoring activity of the reporter gene.

Labels

WRN proteins, nucleic acid molecules which encodes such proteins, anti-WRN protein antibodies and agonists or antagonists, as described above and below, may be labeled with a variety of molecules, including for example, fluorescent molecules, toxins, and radionuclides. Representative examples of fluorescent molecules include fluorescein, Phycobili proteins, such as phycoerythrin, rhodamine, Texas red and luciferase. Representative examples of toxins include ricin, abrin diphtheria toxin, cholera toxin, gelonin, pokeweed antiviral protein, tritin, Shigella toxin, and Pseudomonas exotoxin A. Representative examples of radionuclides include Cu-64, Ga-67, Ga-68, Zr-89, Ru-97, Tc-99m, Rh-105, Pd-109, In-111, I-123, I-125, I-131, Re-186, Re-188, Au-198, Au-199, Pb-203, At-211, Pb-212 and Bi-212. In addition, the antibodies described above may also be labeled or conjugated to one partner of a ligand binding pair. Representative examples include avidin-biotin, and riboflavin-riboflavin binding protein.

Methods for conjugating or labeling the WRN proteins, nucleic acid molecules which encode such proteins, anti-WRN protein antibodies and agonists or antagonists, as discussed above, with the representative labels set forth above may be readily accomplished by one of ordinary skill in the art (see Trichothecene Antibody Conjugate, U.S. Pat. No. 4,744,981,; Antibody Conjugate, U.S. Pat. No. 5,106,951; Fluorogenic Materials and Labeling Techniques, U.S. Pat. No. 4,018,884; Metal Radionuclide Labeled Proteins for Diagnosis and Therapy, U.S. Pat. No. 4,897,255; and Metal Radionuclide Chelating Compounds for Improved Chelation Kinetics, U.S. Pat. No. 4,988,496; see also Inman, Methods In Enzymology, Vol. 34, Affinity Techniques, Enzyme Purification: Part B, Jakoby and Wilchek (eds.), Academic Press, New York, p. 30, 1974; see also Wilchek and Bayer, "The Avidin-Biotin Complex in Bioanalytical Applications," Anal. Biochem. 171:1-32, 1988).

Pharmaceutical Compositions

As noted above, the present invention also provides a variety of pharmaceutical compositions, comprising one of the above-described WRN proteins, nucleic acid molecules, vectors, antibodies, host cells, agonists or antagonists, along with a pharmaceutically or physiologically acceptable carrier, excipients or diluents. Generally, such carriers should be nontoxic to recipients at the dosages and concentrations employed. Ordinarily, the preparation of such compositions entails combining the therapeutic agent with buffers, antioxidants such as ascorbic acid, low molecular weight (less than about 10 residues) polypeptides, proteins, amino acids, carbohydrates including glucose, sucrose or dextrins, chelating agents such as EDTA, glutathione and other stabilizers and excipients. Neutral buffered saline or saline mixed with nonspecific serum albumin are exemplary appropriate diluents.

In addition, the pharmaceutical compositions of the present invention may be prepared for administration by a variety of different routes. In addition, pharmaceutical compositions of the present invention may be placed within containers, along with packaging material which provides instructions regarding the use of such pharmaceutical compositions. Generally, such instructions will include a tangible expression describing the reagent concentration, as well as within certain embodiments, relative amounts of excipient ingredients or diluents (e.g., water, saline or PBS) which may be necessary to reconstitute the pharmaceutical composition.

Methods of Treating or Preventing Werner's Syndrome

The present invention also provides methods for treating or preventing Werner's Syndrome (or related diseases), comprising the step of administering to a patient a vector (e.g., expression vector, viral vector, or viral particle containing a vector) or nucleic acid molecules alone, as described above, thereby reducing the likelihood or delaying the onset of Werner's Syndrome (or the related disease).

Similarly, therapeutic peptides, peptidomimetics, or small molecules may be used to delay onset of Werner's Syndrome, lessen symptoms, or halt or delay progression of the disease. Such therapeutics may be tested in a transgenic animal model that expresses mutant protein, wild-type and mutant protein, or in an in vitro assay system (e.g., a helicase assay such as that described by Bjornson et al., Biochem. 3307:14306-14316, 1994).

As noted above, the present invention provides methods for treating or preventing Werner's Syndrome through the administration to a patient of a therapeutically effective amount of an antagonist or pharmaceutical composition as described herein. Such patients may be identified through clinical diagnosis based on the classical symptoms of Werner's Syndrome.

As will be evident to one of skill in the art, the amount and frequency of administration will depend, of course, on such factors as the nature and severity of the indication being treated, the desired response, the condition of the patient, and so forth. Typically, the compositions may be administered by a variety of techniques, as noted above.

Within other embodiments of the invention, the vectors which contain or express the nucleic acid molecules which encode the WRN proteins described above, or even the nucleic acid molecules themselves may be administered by a variety of alternative techniques, including for example administration of asialoosomucoid (ASOR) conjugated with poly-L-lysine DNA complexes (Cristano et al., PNAS 92122-92126, 1993), DNA linked to killed adenovirus (Curiel et al., Hum. Gene Ther. 3(2):147-154, 1992), cytofectin-mediated introduction (DMRIE-DOPE, Vical, Calif.), direct DNA injection (Acsadi et al., Nature 352:815-818, 1991); DNA ligand (Wu et al., J. of Biol. Chem. 264:16985-16987, 1989); lipofection (Felgner et al., Proc. Natl. Acad. Sci. USA 84:7413-7417, 1989); liposomes (Pickering et al., Circ. 89(1):13-21, 1994; and Wang et al., PNAS 84:7851-7855, 1987); microprojectile bombardment (Williams et al., PNAS 88:2726-2730, 1991); and direct delivery of nucleic acids which encode the WRN protein itself either alone (Vile and Hart, Cancer Res. 53: 3860-3864, 1993), or utilizing PEG-nucleic acid complexes.


Claim 1 of 6 Claims

1. A purified antibody which specifically binds to a WRN gene product comprising the amino acid sequence set forth in SEQ ID NO:71.
 

 

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