WO2011093647A2 - Genes implicated in osteoarthritis and use thereof - Google Patents

Abstract

The present invention relates to a composition for preventing or treating arthritis, a diagnosis kit for arthritis, a method for screening a composition for treating arthritis and a method for preventing or treating arthritis. The present invention ensures the maintenance and survival of chondrocytes essential for physiological functions of connective tissue, such that it is promising for preventing or treating arthritis fundamentally.

Description

GENES IMPLICATED IN OSTEOARTHRITIS AND USE THEREOF

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION

The present invention relates to genes implicated in osteoarthritis and their novel uses for preventing and treating osteoarthritis.

DESCRIPTION OF THE RELATED ART

Osteoarthritis is a multiple disease that occurs in humans more often than any other known diseases. It is a disease that primarily affects aged adults, where 70- 80% of the population over 65 years of age and almost 100% of the population over 75 years old have some form of osteoarthritis. In Korea, more than 10% of the population suffers from osteoarthritis, and the prevalence rate is increasing rapidly due to the aging of the society. There are estimated more than 500 million osteoarthritis patients around the world with the increase in human life span and longer social activity. Thus, treating this disease is an urgent and important part of improving the quality of human life.

Cartilage tissue surrounds the bone like a membrane and functions as a^** structural buffer. It prevents induction of pain or bone abrasion when the bones touch each other. The chondrocyte is the only cellular element in the cartilage tissue which synthesizes collagen and proteoglycan matrix that is critical for retaining normal function. It has an essential role in maintaining functional homeostasis of the articular cartilage tissue. Therefore, preserving the chondrocyte activity is directly related to upholding the structural function of articular cartilage.

For the chondrocytes in the cartilage tissue to function normally, the chondrocytes should generate and differentiate properly, the survival of the generated chondrocyte should be protected and hypertrophic maturation of existing chondrocytes should be continuously inhibited to prevent sclerosis of the cartilage tissue. The main cause of osteoarthritis is by the loss of these basic functions of cartilage chondrocytes with aging (Fig.l). Another key factor causing the osteoarthritis is the loss in the quantity of articular cartilage tissues, which is closely related to proliferation and survival of chondrocytes in the joint (Fig.l). An additional cause of osteoarthritis is sclerosis of the articular cartilage tissues in the joint, which is directly related to hypertrophic maturation of the articular chondrocytes (Fig. 1). When osteoarthritis develops, proteoglycan matrix in the cartilage tissues will undergo mechanical abrasions, which can lead to exposure of bone. At this point, new bone outgrowths called "spurs" due to calcification can deposit at the margins of the joints, causing stiffness around these areas and accelerating the loss of cartilage tissue from the abrasion. These complicated structural changes could lead inflammation and pain, and as the symptoms become worse, could lead to cartilage modification and decreased movement.

Therefore, the most basic and effective approach in treating osteoarthritis is to obtain targets that control the regeneration, differentiation, death and calcification of chondrocytes and develop an effective control mechanism as well (Fig. 2).

The current target for treating arthritis focuses on inhibiting the immune process and most of these treatments are focused on treating rheumatoid arthritis. However, osteoarthritis, involving pain and inflammation by degradation of articular cartilage, and rheumatoid arthritis, which is caused by systemic inflammatory disorder that leads to destruction of articular cartilage are two independent diseases with distinctively different pathological origins and symptoms (Fig. 3). In case of osteoarthritis, anti-inflammatory approaches cannot be considered as an effective means to control the disease since inflammation is not the fundamental cause of the disease.

Currently, there is no effective target substance for treating osteoarthritis commercially available or treatment method for curing osteoarthritis. Therefore, it is critical to develop a new treatment technique that directly attacks the promary cause of osteoarthritis other than the anti-inflammatory approaches.

Throughout this application, various publications and patents are referred and citations are provided in parentheses. The disclosures of these publications and patents in their entities are hereby incorporated by references into this application in order to fully describe this invention and the state of the art to which this invention pertains.

SUMMARY OF THE INVENTION

The present inventor has made intensive studies to develop a novel composition for preventing or treating arthritis fundamentally, far from the conventional therapies focusing on controlling inflammations. As results, the present inventor has discovered that Nkx3.2 (Nk3 homeobox 2) protein and the Nkx3.2 gene are related to maintenance and survival of chondrocytes, which is essential for the maintenance of functional connective tissues.

Accordingly, it is an object of this invention to provide a composition for preventing or treating arthritis.

It is another object of this invention to provide a diagnosis kit for arthritis. It is still another object of this invention to provide a method for screening a composition for treating arthritis.

It is further object of this invention to provide a method for preventing or treating arthritis

Other objects and advantages of the present invention will become apparent from the following detailed description together with the appended claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic diagram showing the pathogenesis of osteoarthritis in terms of maintaining cartilage functions. Fig. 2 is a schematic diagram showing a logical basis for the present invention to be applied in preventing and treating osteoarthritis.

Fig. 3 is a schematic diagram showing problems in current arthritis treatment technology for treating osteoarthritis.

Fig. 4 is a figure showing the expression of Nkx3.2 in articular cartilage chondrocyte analyzed by RT-PCR. The cDNA was synthesized from the total RNA isolated from E16.5 mouse embryo's long bone plate and PCR amplification was performed against GAPDH and Nkx3.2 (lane No. 1). The cDNA was synthesized from the total RNA isolated from chondrocyte of human articular cartilage tissue and PCR amplification was performed against GAPDH and Nkx3.2 (lane No. 2). When the expression level was quantified by using GAPDH expression level as the control, the expression level of Nkx3.2 in articular cartilage chondrocytes were significantly higher than in growth plate chondrocytes.

Fig. 5 is a figure showing the inhibition of Nkx3.2 expression using Nkx3.2 shRNA in articular chondrocytes by RT-PCR. The lane No. 4 is a gene expression knockdown result by infecting chondrocytes isolated from articular cartilage tissue with human Nkx3.2 shRNA virus. Lane No. 1 shows the RT(-) PCR result, lane No. 2 is result of cartilage chondrocytes without infection, lane No. 3 is result of cartilage chondrocyte infected with pLKO control shRNA virus, respectively.

Fig. 6 is a microscopic image showing the death of articular cartilage chondrocyte through inhibiting Nkx3.2 expression. When compared with the articular chondrocyte infected with control shRNA virus (left panel), the cell survival in articular chondrocyte infected with Nkx3.2 shRNA (right panel) was significantly lower.

Fig. 7 is a figure showing the cell death of articular chondrocytes induced by inhibiting the expression of Nkx3.2 by FACS analysis. The cell viability of chondrocytes with inhibited Nkx3.2 expression was analyzed by binding with Annexin-V. When compared with the articular chondrocyte infected with control shRNA virus (left panel), the binding level of Nkx3.2 shRNA infected chondrocyte (right panel) with Annexin-V was significantly higher (right panel).

Fig. 8 is a figure showing the change in the expression level of Nkx3.2 in articular chondrocytes from osteoarthritis patients. Lane No. 1 is a PCR result of GAPDH or Nkx3.2 using cDNA amplified from total RNA isolated from the chondrocytes of normal and osteoarthritis patient articular cartilages. Lane No. 2 is a PCR result of GAPDH and Nkx3.2 using cDNA amplified from total RNA isolated from chondrocytes of human articular cartilage tissue. Lane No. 3 is the result of control RT(-) PCR.

Fig. 9 is a figure showing the change in the expression level of Nkx3.2 in articular cartilage chondrocyte from osteoarthritis patients by Western blot analysis. The total amount of protein was isolated from articular cartilage chondrocytes from normal and osteoarthritis patients. Western blotting was performed against GAPDH and Nkx3.2. When the expression level was quantified by using GAPDH expression level as the control, the expression level of Nkx3.2 protein in osteoarthritis patients was significantly lower than the normal group.

Fig. 10 is a figure showing the comparison of cell death between articular cartilage chondrocytes from normal and osteoarthritis patients using FACS analysis. The cell viability of chondrocyte was analyzed by measuring the binding level with Annexin-V. As shown in the left lanes, a higher level of cell death was detected in osteoarthritis patients (24.3%) compared to the normal group (5.15%). A further induction of cell death by inhibiting NF-κΒ activity showed a significantly higher level of cell death of chondrocytes in osteoarthritis patients (68.11%) when compared to the normal group (19.93%).

Fig. 11 is a figure showing the in vivo effect of Nkx3.2 in osteoarthritis mouse model using Safranin-0 staining method. The left panel is an image of 13-week-old normal mouse hind limb cartilage section stained with Safranin-O, wherein the section stained in red shows the morphology of the normal articular cartilage. The middle panel is an image of 13-week old mouse hind limb cartilage excised and the section stained with Safranin-O. Osteoarthritis was induced at 9-week old via destabilization of the medial meniscus (DMM) of the knee, then infected with lentivirus overexpressing GFP at the same period. The right panel is similar to the middle panel, except that Nkx3.2 is overexpressed instead of GFP. When these two panels are compared, there is a significant level of protection to cartilage tissue loss in the Nkx3.2 overexpressing osteoarthritis induced condition.

Fig. 12 is a figure showing the complementary expression level of Nkx3.2 and Barxl in the cartilage tissue of the developing embryo. This figure is adopted from the result of a previously disclosed reference (2), to describe the background art of the present invention. The interactive complementary expression level of Nkx3.2 and Barxl in the development of cartilage tissue is shown by in situ hybridization.

Fig. 13 is a figure showing the ubiquitination of Ι-κΒ protein by Nkx3.2 is inhibited by Barxl. As shown in the panel No. 1, the induction of Ι-κΒ protein ubiquitination by Nkx3.2 (lane No. 2) is completely inhibited by the co- overexpression of Barxl (lane No. 4). Panel No. 2 shows the protein interaction between Ι-κΒ and Nkx3.2 during the induction of Ι-κΒ ubiquitination (lane No. 2). This protein interaction between Ι-κΒ and Nkx3.2 was lost when Barxl coexisted (lane No. 4).

Fig. 14 is a figure representing the transcriptional activation of NF-κΒ induced by Nkx3.2 is inhibited by Barxl. As shown previously, the functional activation of NF- KB by Nkx3.2 (lane No. 2) was effectively inhibited by Barxl (lane No. 4).

Fig. 15 is a photo image showing the block of Nkx3.2 and Ι-κΒ complex formation by the interaction between Barxl and Nkx3.2. As shown in panel No. 1, the protein interaction between Nkx3.2 and Ι-κΒ (lane No. 2) was dramatically decreased when Barxl was co-overexpressed (lane No. 3). The panel No. 2 shows that in the condition where Nkx3.2, Ι-κΒ and Barxl coexists, the protein interaction between Nkx3.2 and Barxl was stronger than the interaction between Nkx3.2 and I- κΒ (lane No.3).

Fig. 16 is a figure showing the result on induction of chondrocyte death by Barxl overexpression. As shown in lanes No. 3 and 5, higher level of cell death was detected in chondrocyte expressing Barxl, compared to the control vector groups (lane No. 2 and No. 4).

Fig. 17 is a figure showing the result on the effect of inhibiting the chondrocyte death by Barxl knockdown. According to the analysis based on the previous results on induction of chondrocyte death by inhibiting the NF-κΒ (1), when compared to shRNA virus transfected control chondrocytes (lane No. 2), chondrocytes transfected with Barxl shRNA (lane No. 4) showed more effective inhibition in cell death.

Fig. 18 is a figure representing the change in the expression level of Barxl in chondrocyte from the joints of osteoarthritis patients using Western blot analysis. GAPHD and Barxl from chondrocytes isolated from normal and osteoarthritis patients were analyzed by Western blotting. When the expression level was quantified by using GAPDH expression level as the control, the expression level of Barxl in osteoarthritis patients was significantly higher than normal group.

Fig. 19 is a figure representing the comparison of cell death in chondrocytes from normal and osteoarthritis patients using FACS analysis. The cell viability of chondrocyte was analyzed by measuring the binding level with Annexin-V. As shown in the left lanes, a higher level of cell death was detected in osteoarthritis patients (24.3%) compared to the normal group (5.15%). A further induction of cell death by inhibiting NF-κΒ activity showed a significantly higher level of cell death of chondrocytes in osteoarthritis patients (68.11%) when compared to the normal group (19.93%).

DETAILED DESCRIPTION OF THE INVENTION

In one aspect of this invention, there is provided a composition for preventing or treating arthritis, comprising a polypeptide having the amino acid sequence of SEQ ID NO:2.

The present inventor has made intensive studies to develop a novel composition for preventing or treating arthritis fundamentally, far from the conventional therapy focusing on controlling inflammations. As results, the present inventor has discovered that Nkx3.2 (Nk3 homeobox 2) protein and the Nkx3.2 gene are related to maintenance and survival of a chondrocyte which is essential for the function of articular tissue.

The term "polypeptide" as used herein, refers to a linear molecule formed by peptide bonds between amino acid residues. The SEQ ID NO:2 is the amino acid sequence of the Nkx3.2 protein.

According to the present invention, the present inventor has observed that Nkx3.2 is expressed in chondrocytes, and that the Nkx3.2 expression level in articular chondrocytes is much higher than that of growth plate chondrocytes (Fig. 4). This suggests that the physiological function of Nkx3.2 plays a crucial role in articular chondrocytes.

In addition, inhibiting Nkx3.2 expression through RNA knock-down induced effective apoptosis of human articular chondrocytes (Fig. 6 and Fig. 7), and chondrocytes isolated from the tissue of a subject with degenerative arthritis showed much lower Nkx3.2 expression both in RNA and protein level (Fig. 8 and Fig. 9).

Furthermore, Nkx3.2 overexpression in articular tissue inhibited the induction of degenerative arthritis in mice (Fig. 11). These indicate that restoration of Nkx3.2 expression may effectively control the progress degenerative arthritis. Nkx3.2 protein of this invention may encompass sequences having substantial identity to the amino acid sequence of SEQ ID NO: 2. Sequences having the substantial identity show at least 80%, more preferably at least 90%, most preferably at least 95% similarity to the amino acid sequence of nucleic acid of Nkx3.2 protein, as measured using one of the sequence comparison algorithms.

In addition, Nkx3.2 protein of this invention includes the protein having variant amino acid sequence as well as natural-occurring one. The variant of Nkx3.2 protein refers to a protein of different sequence with deletion, insertion, conservative or non-conservative substitution or combination thereof in one or more amino acid residues. Such alteration of amino acid residues not to substantially impair protein activity is well known to one skilled in the art (H.Neurath, R.L.Hill, The Proteins, Academic Press, New York, 1979). Most common amino acid alteration includes Ala/Ser, Val/Ile, Asp/Glu, Thr/Ser, Ala/Gly, Ala/Thr, Ser/Asn, Ala/Val, Ser/Gly, Thy/Phe, Ala/Pro, Lys/Arg, Asp/Asn, Leu/Ile, Leu/Val, Ala/Glu and Asp/Gly, but not limited to.

Optionally, the Nkx3.2 protein may be modified by phosphorylation, sulfation, acrylation, glycosytation, methylation or famesy!ation.

The Nkx3.2 protein or its variants can be prepared by preparation from its natural source, chemical synthesis (Merrifleld, J. Amer. chem. Soc. 85:2149-2156, 1963) or recombinant methods based on DNA sequences (Sambrook, J. et al., Molecular Cloning. A Laboratory Manual, 3rd ed. Cold Spring Harbor Press (2001)).

In another aspect of this invention, there is provided a composition for preventing or treating arthritis, comprising a nucleotide sequence encoding the amino acid sequence of SEQ ID NO:2.

According to a preferred embodiment, the nucleotide sequence of this invention comprises the nucleotide sequence of SEQ ID NO: l.

According to the present invention, the nucleotide sequence of SEQ ID NO:l is the nucleotide sequence of Nkx3.2 gene.

It would be obvious to the skilled artisan that the nucleotide sequences used in this invention are not limited to those listed in the appended Sequence Listings.

For nucleotide sequences, the variations may be purely genetic, i.e., ones that do not result in changes in the protein product. This includes nucleic acids that contain functionally equivalent codons, or codons that encode the same amino acid, such as six codons for arginine or serine, or codons that encode biologically equivalent amino acids.

Considering biologically equivalent variations described hereinabove, the nucleic acid molecule of this invention may encompass sequences having substantial identity to them. Sequences having the substantial identity show at least 80%, more preferably at least 90%, most preferably at least 95% similarity to the nucleic acid molecule of this invention, as measured using one of the sequence comparison algorithms. Methods of alignment of sequences for comparison are well-known in the art. Various programs and alignment algorithms are described in: Smith and Waterman, Adv. Appl. Math. 2:482(1981); Needleman and Wunsch, J. Mo/. Bio. 48:443(1970); Pearson and Upman, Methods in Moi. Biol. 24: 307-31(1988); Higgins and Sharp, Gene 73:237-44(1988); Higgins and Sharp, CABIOS 5:151-3(1989) Corpet et al., Nuc. Acids Res. 16:10881-90(1988) Huang et al., Comp. Appl. BioSci. 8: 155-65(1992) and Pearson et al., Meth. Mo/. Biol. 24:307-31(1994). The NCBI Basic Local Alignment Search Tool (BLAST) [Altschul et al., J. Mol. Biol. 215:403- 10(1990)] is available from several sources, including the National Center for Biological Information (NBCI, Bethesda, Md.) and on the Internet, for use in connection with the sequence analysis programs blastp, blasm, blastx, tblastn and tbiastx. It can be accessed at http://www.ncbi.nlm.nih.gov/BLAST/. A description of how to determine sequence identity using this program is available at http://www.ncbi.nlm.nih.gov/BLAST/blast_help.html. The composition of this invention may be provided as a pharmaceutical composition comprising a pharmaceutically effective amount of the polypeptide or the nucleotide of this invention.

The term "pharmaceutically effective amount" as used herein, refers to an amount enough to show and accomplish efficacies and activities for preventing, alleviating, treating arthritis.

The pharmaceutical composition of this invention includes a pharmaceutically acceptable carrier besides the active ingredient compound. The pharmaceutically acceptable carrier contained in the pharmaceutical composition of the present invention, which is commonly used in pharmaceutical formulations, but is not limited to, includes lactose, dextrose, sucrose, sorbitol, mannitol, starch, rubber arable, potassium phosphate, arginate, gelatin, potassium silicate, microcrystalline cellulose, polyvinylpyrrolidone, cellulose, water, syrups, methylcellulose, methylhydroxy benzoate, propylhydroxy benzoate, talc, magnesium stearate, and mineral oils. The pharmaceutical composition according to the present invention may further include a lubricant, a humectant, a sweetener, a flavoring agent, an emuisifier, a suspending agent, and a preservative. Details of suitable pharmaceutically acceptable carriers and formulations can be found in Remington's Pharmaceutical Sciences (19th ed., 1995).

The pharmaceutical composition according to the present invention may be administered orally or parenterally, and preferably, administered parenterally. For parenteral administration, it may be administered intravenously, subcutaneously, intramusculerly, intraperitoneally, transdermal^ or intra-articularly. Most preferably, it is administered intra-articularly

A suitable dosage amount of the pharmaceutical composition of the present invention may vary depending on pharmaceutical formulation methods, administration methods, the patient's age, body weight, sex, pathogenic state, diet, administration time, administration route, an excretion rate and sensitivity for a used pharmaceutical composition. Preferably, pharmaceutical composition of the present invention may be administered with a daily dosage of 0.001-10000 mg/kg (body weight). According to the conventional techniques known to those skilled in the art, the pharmaceutical composition according to the present invention may be formulated with pharmaceutically acceptable carrier and/or vehicle as described above, finally providing several forms including a unit dose form and a multi-dose form. Non-limiting examples of the formulations include, but not limited to, a solution, a suspension or an emulsion in oil or aqueous medium, an elixir, a powder, a granule, a tablet and a capsule, and may further comprise a dispersion agent or a stabilizer.

According to a more preferred embodiment, the composition of this invention is contained in a gene delivery system.

The term "gene delivery system" as used herein, refers to any forms of carriers that harbor and transport exogenous nucleic acid molecules to a target cell or tissue. The ideal gene delivery system should be harmless to human body, suitable for mass production, and capable of effective transportation of the target gene.

To construct the present gene delivery system of this invention, it is preferred that the nucleotide sequence of this invention is contained in a suitable expression construct. According the expression construct, it is preferred that the nucleotide sequence of this invention is operatively linked to a promoter. The term "operatively linked" refers to functional linkage between a nucleic acid expression control sequence (such as a promoter, signal sequence, or array of transcription factor binding sites) and a second nucleic acid sequence, wherein the expression control sequence affects transcription and/or translation of the nucleic acid corresponding to the second sequence. According to the present invention, the promoter linked to the nucleotide sequence of this invention is operable in, preferably, animal, more preferably, mammalian cells, to control transcription of the nucleotide sequence of this invention, including the promoters derived from the genome of mammalian cells or from mammalian viruses, for example, CMV (cytomegalovirus) promoter, the adenovirus late promoter, the vaccinia virus 7.5K promoter, SV40 promoter, HSV tk promoter, RSV promoter, EF1 alpha promoter, metallothionein promoter, beta-actin promoter, human IL-2 gene promoter, human IFN gene promoter, human IL-4 gene promoter, human lymphotoxin gene promoter and human GM-CSF gene promoter. Most preferably, the promoter is CMV promoter.

The gene delivery system of the present invention is constructed in a variety of forms, preferably, (i) naked recombinant DNA molecule, (ii) plasmid, (iii) viral vector, or (iv) liposome or neosome containing naked recombinant DNA molecule and plasmid. In some cases, endocytosis using the covalent bonds with signal transduction peptide may be applied.

The Nkx3.2-encoding nucleotide sequence may be applied to a multitude of gene delivery systems useful in gene therapy, preferably, plasmid, adenovirus (Lockett U, et al., Clin. Cancer Res. 3:2075-2080(1997)), adeno-associated virus (AAV, Lashford LS., et al., Gene Therapy Technologies, Applications and Regulations Ed. A. Meager, 1999), retrovirus (Gunzburg WH, et al., Retroviral vectors. Gene Therapy Technologies, Applications and Regulations Ed. A. Meager, 1999), lentivirus (Wang G. et al., J. Clin. Invest. 104(11):R55-62(1999)), herpes simplex virus (Chamber R., et al., Proc. Natl. Acad. Sci USA 92:1411-1415(1995)), vaccinia virus (Puhlmann M. et al., Human Gene Therapy 10:649-657(1999)), liposome (Methods in Molecular Biology, Vol 199, S.C. Basu and M. Basu (Eds.), Human Press 2002) or neosome. Most preferably, the gene delivery system of this invention is constructed by incorporating the Nkx3.2-encoding nucleotide sequence to a lentivirus.

Where the present gene delivery system is constructed on the basis of viral vector construction, the contacting is performed as conventional infection methods known in the art. The infection of hosts using viral vectors is well described in the above-cited publications.

Where the present gene delivery system is a naked recombinant DNA molecule or plasmid, the Nkx3.2-encoding sequence to be delivered are introduced into cells by microinjection (Capecchi, M.R., Cell, 22:479(1980) and Harland and Weintraub, J. Cell Biol. 101: 1094-1099(1985)), calcium phosphate co-precipitation (Graham, F.L. et al., Virology, 52:456(1973) and Chen and Okayama, Mol. Cell. Biol. 7:2745-2752(1987)), electroporation (Neumann, E. et al., EMBO J., 1:841(1982) and Tur-Kaspa et al., Mol. Cell Biol., 6:716-718(1986)), liposome-mediated transfection (Wong, T.K. et al., Gene, 10:87(1980) and Nicolau and Sene, Biochim. Biophys. Acta, 721: 185-190(1982); and Nicolau et al., Methods Enzymol., 149:157- 176(1987)), DEAE-dextran treatment (Gopal, Mol. Cell Biol., 5: 1188-1190(1985)), and particle bombardment (Yang et al., Proc. Natl. Acad. Sci., 87:9568-9572(1990)).

According to a preferred embodiment, the arthritis of this invention is a degenerative arthritis.

The term "degenerative arthritis" as used herein, refers to a disease or disorder resulted from the damage of articular tissue due to the quantitative loss of cartilage tissue. As used herein, "degenerative arthritis" is used interchangeably with "osteoarthritis".

The composition of the present invention contributes to the correction of chondrocyte dysfunction, allowing for activation of restoration of articular tissue. Therefore, the present invention provides a fundamental therapy for degenerative arthritis, whereas the conventional approaches focusing on controlling inflammations are only effective on rheumatoid arthritis caused by immune system disorders.

In still another aspect of this invention, there is provided a diagnosis kit for arthritis comprising an antibody or an aptamer which specifically binds to a polypeptide having the amino acid sequence of SEQ ID NO:2.

The term "diagnosis" as used herein, includes the following matters: (a) to determine susceptibility of a subject to a particular disease or disorder; (b) to evaluate whether a subject has a particular disease or disorder; (c) to assess a prognosis of a subject suffering from a specific disease or disorder; or (d) therametrics {e.g., monitoring conditions of a subject to provide an information to treatment efficacy).

According to the present invention, where it is confirmed in a subject by the method mentioned above that the expression level of the polypeptide having the amino acid sequence of SEQ ID NO:2 is higher than that of normal person, the subject is determined to have lower risk of arthritis due to enhanced viability and activity of growth plate chondrocytes.

According to the present invention, diagnosis of arthritis could be carried out according to conventional immunoassay procedures, i.e., antigen-antibody reaction. These immunoassay could be performed according to various immunoassay- or immunostaining- protocols previously developed.

For example, where the diagnosis is carried out according to the radioimmunoassay method, the radioisotope {e.g., C¹⁴, I¹²⁵, P³² and S³⁵) labeled antibody may be used to detect the marker of the present invention.

The antibody against the polypeptide used in this invention may be polyclonal or monoclonal, preferably monoclonal. The antibody could be prepared according to conventional techniques such as a fusion method (Kohler and Milstein, European Journal of Immunology, 6: 511-519 (1976)), a recombinant DNA method (USP 4,816,56) or a phage antibody library (Clackson et al, Nature, 352: 624-628 (1991) and Marks et al, J. Mol. Biol., 222:58, 1-597 (1991)). The general procedures for antibody production are described in Harlow, E. and Lane, D., Using Antibodies: A Laboratory Manual, Cold Spring Harbor Press, New York, 1988; Zola, H., Monoclonal Antibodies: A Manual of Techniques, CRC Press, Inc., Boca Raton, Florida, 1984; and Coligan, CURRENT PROTOCOLS IN IMMUNOLOGY, Wiley/Greene, NY, 1991. For example, the preparation of hybridoma cell lines for monoclonal antibody production is done by fusion of an immortal cell line and the antibody producing lymphocytes. This can be done by techniques well known in the art. Polyclonal antibodies may be prepared by injection of the target protein antigen to suitable animal, collecting antiserum containing antibodies from the animal, and isolating specific antibodies by any of the known affinity techniques.

The final signal intensity measured by the above-mentioned immunoassay procedures is indicative of arthritis. When the signal to the target of this invention from a sample to be diagnosed is weaker than normal samples, the sample can be diagnosed as arthritis.

According to another modification of this invention, aptamer having a specific binding affinity to the target of the present invention may be used instead of antibody. The term "aptamer" used herein refers to a single-stranded nucleic acid (RNA or DNA) or peptide molecule which binds to a particular target material with high affinity and specificity. General descriptions of aptamer are disclosed in Bock LC et al., Nature 355(6360) :564-6( 1992); Hoppe-Seyler F, Butz K "Peptide aptamers: powerful new tools for molecular medicine". J Mo/ Med. 78 (8): 426-30 (2000); and Cohen BA, Colas P, Brent R. "An artificial cell-cycle inhibitor isolated from a combinatorial library". Proc Natl Acad Sci USA. 95 (24): 14272-7 (1998).

In still another aspect of this invention, there is provided a diagnosis kit for arthritis comprising a primer or a probe which specifically binds to a nucleotide sequence encoding the amino acid sequence of SEQ ID NO:2.

The term "nucleotide" used herein refers to deoxyribonucleotide or ribonucleotide existing as single-stranded or double-stranded form, and also includes analogues of natural-occurring nucleotides unless otherwise indicated (Scheit, Nucleotide Analogs, John Wiley, New York(1980); Uhlman ¾ Peyman, Chemical Reviews, 90:543-584(1990)).

The term "primer" used herein refers to a oligonucleotide which is capable of acting as a point of initiation of synthesis when placed under conditions in which synthesis of a primer extension product which is complementary to a nucleic acid strand is induced, i.e., in the presence of four different nucleoside triphosphates and a thermostable enzyme in an appropriate buffer and at a suitable temperature. Preferably, the primer is single-stranded and deoxyribonucleotide.

The primer used in this invention includes naturally occurring d MP (dAMP, dGMP, dCMP and dTMP), modified nucleotide and non-natural nucleotide. In addition, the primer may also include ribonucleotide.

The primer of the present invention can be an extension primer forming a sequence complementary to target nucleic acid by template-dependent polymerase

The extension primer of this invention includes a hybridizable nucleotide sequence complementary to the 1st position in target nucleic acid.

The term "complementary" used herein refers to a sequence having complementarity to the extent that the sequence hybridizes or anneals specifically with the target nucleotide sequence under certain hybridization or annealing conditions. In this regard, the term "complementary" used herein refers to both "substantially complementary" and "perfectly complementary", and preferably, "perfectly complementary".

The term "substantially complementary sequence" used with reference to primer sequence herein comprises the sequence including partial mismatch base sequences where it is able to specifically hybridize with the target nucleotide.

Primers should be long enough to be capable of priming the extension product under the presence of polymers. The suitable length of primers will depend on many factors, including temperature, application and source of primer, generally, 15-30 nucleotides in length. In general, shorter primers need lower temperature to form stable hybridization duplexes to templates. The term "annealing" or "priming" as used herein refers to the apposition of an oligodeoxynucleotide or nucleic acid to a template nucleic acid, whereby said apposition enables the polymerase to polymerize nucleotides into a nucleic acid molecule which is complementary to the template nucleic acid or a portion thereof.

The sequences of primers are not required to have perfectly complementary sequence to templates. The sequences of primers may comprise some mismatches, so long as they can be hybridized with templates and serve as primers. Therefore, the primers of this invention are not required to have perfectly complementary sequence to the nucleotides of this invention; it is sufficient that they have complementarity to the extent that they anneals specifically to the nucleotide sequence of this invention for acting as a point of initiation of synthesis. The primer design may be conveniently performed with referring to the above-mentioned nucleotide sequences. For instance, the primer design may be carried out using computer programs for primer design {e.g., PRIMER 3 program).

The term "nucleic acid molecule" used herein has comprehensive meaning including DNA (gDNA and cDNA) and RNA molecule. A nucleotide, which is a basic construct unit of nucleic acid molecule, includes nucleotide analogues with modified sugar or base, as well as natural-occurring nucleotides (Scheit, Nucleotide Analogs, John Wiley, New York (1980); Uhtman ¾ Peyman, Chemical Reviews, 90:543- 584(1990)).

Where the starting material of this invention is gDNA, isolation of gDNA may be carried out by conventional method known to one skilled in the art (Rogers & Bendich (1994)).

Where the starting material is mRNA, isolation of total RNA may be carried out by conventional method known to one skilled in the art (Sambrook, J. et al., Molecular Cloning. A Laboratory Manual, 3rd ed. Cold Spring Harbor Press(2001); Tesniere, C. et al., Plant Mol. Biol. Rep., 9:242(1991); Ausubel, F.M. et al., Current Protocols in Molecular Biology, John Willey & Sons(1987); and Chomczynski, P. et al., Anal. Biochem. 162:156(1987)). Isolated total RNA is synthesized as cDNA using reverse transcriptase. The mRNA has a poly-A tail because said total RNA is derived from human e.g., arthritis patients), thus cDNA can be synthesized readily using oligo dT primer and reverse transcriptase (PNAS USA, 85:8998(1988); Libert F, et al., Science, 244:569(1989); and Sambrook, J. et al., Molecular Cloning. A Laboratory Manual, 3rd ed. Cold Spring Harbor Press(2001)). In the kit of this invention, identifying certain sequence may be carried out by various methods known to one skilled in the art, e.g., fluorescent in situ hybridization (FISH) in situ (FISH), direct DNA sequence analysis, PFGE analysis, southern blotting, single-strand confirmation analysis (SSCA, Orita et al., PNAS, USA 86:2776(1989)), RNase protection assay (Finkelstein et al., Genomics, 7: 167(1990)), dot blot analysis, Denaturing gradient gel electrophoresis (DGGE, Wartell et al., Nucl.Acids Res., 18:2699(1990)), method using nucleotide mismatching- recognition protein (e.g., mutS protein of E coli) (Modrich, Ann. Rev. Genet., 25:229-253(1991)) and allele- specific PCR, but not limited to.

Other methods are performed usually by a probe or a primer complementary to the nucleotide sequence of this invention. For example, in RNase protection assay, a riboprobe complementary to the sequence containing nucleotide of this invention is used. Said riboprobe is hybridized with DNA or mRNA isolated from human, and then cleaved by RNase A which enables detecting mismatches. If some mismatches recognized by RNase A exist, a smaller band would be observed.

In analysis using hybridization signal, a probe complementary to the sequence containing nucleotide of this invention is used.

The term "probe" used herein refers to a linear oligomer of natural or modified monomers or linkages, including deoxyribonucleotides, ribonucleotides and the like, which is capable of specifically hybridizing with a target nucleotide sequence, whether occurring naturally or produced synthetically. The probe used in the present method may be prepared in the form of preferably single-stranded and oligodeoxyribonucleotide probe.

The probe of the present invention may be perfectly complementary to said nucleotide sequence, but also substantially complementary sequence not to disturbing specific hybridization, would act as the probe of the present invention.

Preferably, the probe of the present invention comprises the sequence hybridizable to the nucleotide sequence of this invention. More preferably, 3' end or 5' end of said probe has bases complementary to said nucleotide. Commonly, stability of duplex formed by hybridization depends on match of end sequence. Thus, such duplex may be dissociated under stringent condition when a probe is not hybridized at end portion.

The detailed conditions for hybridization can be found in Joseph Sambrook, et al., Molecular Cloning, A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y.(2001) and Haymes, B. D., et al., Nucleic Acid Hybridization, A Practical Approach, IRL Press, Washington, D.C. (1985). Stringent conditions for hybridization can be determined by adjusting temperature, ionic strength (buffer concentration) and the presence of chemical compound such as organic solvent. These conditions can vary depending on the sequence to be hybridized.

According to a preferred embodiment, the nucleotide sequence of this invention comprises the nucleotide sequence of SEQ ID NO:l.

According to a preferred embodiment, the arthritis of this invention is a degenerative arthritis.

According to a preferred embodiment, low expression level of the nucleotide sequence or the polypeptide is indicative of increased risk of arthritis in a subject.

The term "low expression level" used herein refers to significantly lower expression level of the nucleotide sequence or polypeptide of this invention as compared with that found in a normal person, and preferably, a decreased expression level by 5-65% compared with that of a normal person.

In still another aspect of this invention, there is provided a method for screening a composition for treating arthritis, comprising the steps of:

(a) contacting a substance of interest to a cell comprising the nucleotide sequence of SEQ ID NO:l; and

(b) measuring the expression level of the nucleotide sequence of SEQ ID NO:l, wherein when the expression level of the nucleotide sequence of SEQ ID NO:l is increased, the substance is determined as the therapeutic drug candidate for treating arthritis.

According to the present invention, a cell comprising the nucleotide sequence of SEQ ID NO: l is contacted to a substance of interest. Preferably, the cell comprising the nucleotide sequence of SEQ ID NO: l is a human chondrocyte. The term "substance" used with reference to screening method herein refers to an unknown agent used in screening process investigating whether the expression level of the nucleotide sequence of SEQ ID NO: l is changed. The substance comprises, but not limited to, chemical compound, nucleotide, antisense-RNA, siRNA(small interference RNA) and natural extract. Afterwards, the expression level of the nucleotide sequence of SEQ ID NO:l is measured in the cell treated with said substance. Measurement of expression _ level, is performed as described above, and if the expression level of the nucleotide sequence of SEQ ID NO:l is increased, the substance is determined as the therapeutic drug candidate for treating arthritis.

According to a preferred embodiment, the cell of this invention is a chondrocyte. According to a preferred embodiment, the arthritis of this invention is a degenerative arthritis.

In still another aspect of this invention, there is provided a composition for preventing or treating arthritis, comprising a substance increasing the expression level of the nucleotide sequence of SEQ ID NO: l.

The term "increasing the expression level" used herein refers to increasing gene expression in measurable degrees, and preferably, increasing up to more than 130% of a normal person.

A substance increasing the expression level of the nucleotide sequence includes, but not limited to, a substance increasing transcription efficiency {e.g., transcription factor), a substance enhancing the stability of mRNA {e.g., CAP-binding protein), or a substance promoting translation of mRNA {e.g., TIF : translation initiation factor). In still another aspect of this invention, there is provided a composition for preventing or treating arthritis, comprising a substance increasing activity of a polypeptide having the amino acid sequence of SEQ ID NO: 2

The term "increasing activity" used herein refers to increasing indigenous biological function of protein in measurable degrees, and preferably, increasing up to more than 130% of a normal person.

Increase of activity includes increase of stability leading to ultimate improvement of activity, as well as simply increase of function.

The substance increasing activity or stability of a polypeptide of this invention includes, but not limited to, various proteins strengthening a-helix structure, PEG (polyethylene glycol) for PEGylation and human serum albumin.

In still another aspect of this invention, there is provided a method for preventing or treating arthritis, which comprises administering to a subject the composition of this invention.

As the common descriptions regarding the pharmaceutical composition of this invention and administration thereof are mentioned above, they are omitted herein to avoid excessive overlaps. In still another aspect of this invention, there is provided a composition for preventing or treating arthritis, comprising a nucleic acid molecule suppressing the expression level of the nucleotide sequence encoding the amino acid sequence of SEQ ID NO:4.

The present inventor has made intensive studies to develop a novel composition for preventing or treating arthritis fundamentally, far from the conventional therapy focusing on controlling inflammations. As results, the present inventor has discovered that the BarXl protein and the BarXl gene, along with the Nkx3.2 protein and the Nkx3.2 gene, are related to occurrence and progress of arthritis chondrocyte. According to the present invention, SEQ ID NO:4 is the amino acid sequence of BarXl protein.

The present inventor has observed that the Barxl gene inhibits Nkx3.2-induced ubiquitination of Ι-κΒ protein (1) which is required for survival of chondrocytes (Fig. 13), and that Barxl gene also suppresses Nkx3.2-induced transcription activation of NF-KB remarkably (Fig. 14). Accordingly, it is indicated that suppressing the expression of the Barxl gene leads to the promotion of NF- Β activity which is related to survival of chondrocytes.

The term "suppressing the expression" used herein refers to a modification on nucleotide sequence causing function decline of target gene, and preferably, making expression level of target gene undetectable or non-significant.

According to a preferred embodiment, the nucleotide sequence of this invention comprises the nucleotide sequence of SEQ ID NO:3.

According to the present invention, the nucleotide sequence of SEQ ID NO:3 is the nucleotide sequence of Barxl gene.

As the common descriptions regarding nucleotide of the present invention are mentioned above, they are omitted herein to avoid excessive overlaps.

According to a preferred embodiment, the nucleic acid molecule of this invention is shRNA, siRNA, miRIMA, ribozyme, PNA (peptide nucleic acid) or antisense oligonucleotide. More preferably, the nucleic acid molecule of this invention is shRNA.

The term "shRNA (small hairpin RNA)" used herein refers to a 50-70 bp single- stranded nucleotide forming a stem-loop structure in vivo. In other words, shRNA is a RNA sequence producing a tight hairpin structure to inhibit gene expression through RNA interference. Long complementary RNA of 19-29 nucleotides located at both side of 5-10 nucleotides-loop form base pairing to shape stem flanking 5-10 nucleotides loop. shRNA is incorporated in a vector comprising U6 promoter to be expressed continuously and transduced to a daughter cell for inheritance of gene expression suppression. shRNA hairpin structure is cleaved by intracellular mechanism to be siRNA and binds to RISC (RNA-induced silencing complex). These RISC bind to mRNA and cleave it. shRNA is transcirbed by RNA polymerase ΙΠ.

The term "siRNA" used herein refers to a short double-stranded RNA molecule mediating RNA interference through cleavage of certain mRNA. siRNA is composed of sense RNA strand homologous with mRNA of target gene, and antisense RNA strand complementary to mRNA. The siRNA to inhibit expression of a target gene provides effective gene knock-down method or gene therapy method. The siRNA of this invention is not restricted to a RNA duplex of which two strands are completely paired and may comprise non-paired portion such as mismatched portion with non- complementary bases and bulge with no opposite bases. The overall length of the siRNA is 10-100 nucleotides, preferably, 15-80 nucleotides, and more preferably, 20- 70 nucleotides.

The siRNA may comprise either blunt or cohesive end so long as it enables to silent the target gene expression due to RNAi effect. The cohesive end may be prepared in 3'-end overhanging structure or 5'-end overhanging structure. The number of overhanging bases is, for example, 1-8 bases, preferably 2-6 bases, but not limited to. In addition, siRNA may contain low molecular RNA (e.g., natural occurring RNA such as tRNA, rRNA, or artificial RNA molecule) in overhanging portion at one end. The terminal structure of siRNA need not to be a cleavage structure at both ends, thus a stem-loop structure with one end of double-stranded RNA connected to linker RNA is possible. The length of linker is not limited insofar paring of stem portion is not hindered.

The term "miRNA (microRNA)" used herein refers to a single-stranded RNA molecule that regulate gene expression, composed of 20-50 nucleotides, preferably 20-45 nucleotides, more preferably 20-40 nucleotides, even more preferably 20-30 nucleotides, and most preferably 21-23 nucleotides. miRNA is an oligonucleotide having short stem-loop structure which is not expressed intraceilularly. miRNA has partial or overall homology with one or more mRNAs and inhibits target gene expression by complementary paring with said mR A.

The term "ribozyme" used herein refers to a kind of RNA molecule with enzymatic activity that recognizes and cleaves specific RNA sequence. Ribozyme is composed of a target mRNA-complementary region and target mRNA-cleaving region.

The term "PNA (Peptide nucleic acid)" used herein refers to a molecule having the characteristics of both nucleic acid and protein, which is capable of complementarily binding to DNA or RNA. PNA was first reported in 1999 as similar DNA in which nucleobases are linked via a peptide bond (Nielsen PE, Egholm M, Berg RH, Buchardt O, "Sequence-selective recognition of DNA by strand displacement with a thymine-substituted polyamide", Science 1991, Vol. 254: pp 1497- 1500). PNA is absent in the natural world and artificially synthesized through a chemical method. PNA is reacted with a natural nucleic acid having a complementary base sequence through hybridization response, forming double strand. In the double strand with the same length, PNA/DNA and PNA/RNA double strand are more stable than DNA/DNA and DNA/RNA double strand, respectively. The form of repeating N-(2-aminoethyl)-glycine units linked by amide bonds is commonly used as a basic peptide backbone. In this context, the backbone of peptide nucleic acid is electrically neutral different from that of natural nucleic acids having negative charge. Four bases of nucleic acid present in PNA are almost the same to those of natural nucleic acid in the respect of spatial size and distance between nucleobases. PNA has not only a chemical stability compared with natural nucleic acid, but also a biological stability due to no degradation by a nuclease or protease.

The term "antisense oligonucleotide" used herein is intended to refer to nucleic acids, preferably, DNA, RNA or its derivatives, that are complementary to the base sequences of a target mRNA, characterized in that they bind to the target mRNA and interfere its translation to protein. The antisense oligonucleotide of the present invention refers to DNA or RNA sequences which are complementary to the base sequences of the Barxl mRNA, characterized in that they bind to the Barxl mRNA and interfere their translation to protein, translocation into cytoplasm, or essential activities to other biological functions.

The antisense nucleic acids may be modified at above one or more positions of base, sugar or backbone (De Mesmaeker et al., Curr Opin Struct Biol., 5(3): 343-55 (1995)). The nucleic acid backbone may be modified by phosphothioate, phosphotriester, methyl phosphonate, single chain alkyl, cycloalkyl, single chain heteroatomic, heterocyclic bond between sugars, and so on. In addition, the antisense nucleic acids may include one or more substituted sugar moieties. The antisense nucleic acids may include a modified base. The modified base includes hypoxanthine, 6-methyladenine, 5-me pyrimidine (particularly, 5-methylcytosine), 5- hydroxymethylcytosine (HMC), glycosyl HMC, gentobiosyl HMC, 2-aminoadenine, 2- thiouracil, 2-thiothymine, 5-bromouracil, 5-hydroxymethyluracil, 8-azaguanine, 7- deazaguanine, N6 (6-aminohexyl) adenine, 2, 6-diaminopurine, and so on.

The composition of this invention may be provided as a pharmaceutical composition comprising pharmaceutically effective amount of the polypeptide or the nucleotide of this invention. As the common descriptions regarding pharmaceutical composition are mentioned above, they are omitted herein to avoid excessive overlaps.

According to a preferred embodiment, the nucleic acid molecule of this invention is contained in a gene delivery system.

As the common descriptions regarding pharmaceutical composition are mentioned above, they are omitted herein to avoid excessive overlaps.

According to a preferred embodiment, the arthritis of this invention is a degenerative arthritis.

In still another aspect of this invention, there is provided a diagnosis kit for arthritis comprising an antibody or an aptamer which specifically binds to a polypeptide having the amino acid sequence of SEQ ID NO:4.

As the common descriptions regarding a diagnosis kit, an antibody and an aptamer are mentioned above, they are omitted herein to avoid excessive overlaps.

According to the present invention, where it is confirmed in a subject by the method mentioned above that the signal of the polypeptide having the amino acid sequence of SEQ ID NO:4 is stronger than that of normal person, the subject is determined to have lower higher of arthritis.

In still another aspect of this invention, there is provided a diagnosis kit for arthritis comprising a primer or a probe which specifically binds to a nucleotide sequence encoding the amino acid sequence of SEQ ID NO:4.

As the common descriptions regarding a primer and a probe are mentioned above, they are omitted herein to avoid excessive overlaps.

According to a preferred embodiment, the nucleotide sequence of this invention comprises the nucleotide sequence of SEQ ID NO:3.

According to a preferred embodiment, the arthritis of this invention is a degenerative arthritis.

According to a preferred embodiment, a subject with high expression level of said nucleotide or said polypeptide has increased risk of arthritis.

The term "high expression level" used herein refers to significantly higher expression level of the nucleotide or polypeptide of this invention as compared with a normal person, and preferably, a increased expression level by more than 130% compared with that of a normal person. In still another aspect of this invention, there is provided a method for screening a composition for treating arthritis, comprising the steps of:

(a) contacting a substance of interest to a cell comprising the nucleotide sequence of SEQ ID NO:3; and

(b) measuring the expression level of the nucleotide sequence of SEQ ID NO:3, wherein when the expression level of the nucleotide sequence of SEQ ID NO:3 is decreased, the substance is determined as the therapeutic drug candidate for treating arthritis.

As the common descriptions regarding a screening method are mentioned above, they are omitted herein to avoid excessive overlaps.

In still another aspect of this invention, there is provided a method for screening a composition for treating arthritis, comprising the steps of:

(a) contacting a substance of interest to a cell comprising the polypeptide having the amino acid sequence of SEQ ID NO:4; and

(b) analyzing the binding of said polypeptide and the substance of interest, wherein when the binding of said polypeptide and the substance of interest is increased, the substance is determined as the therapeutic drug candidate for treating arthritis.

According to the present invention, the Barxl gene efficiently inhibits Nkx3.2- induced ubiquitination of Ι-κΒ protein which activates NF- κ B (Fig. 13). In addition, it is confirmed that direct binding between Barxl and Nkx3.2 intercept the binding of I- B and Nkx3.2 which is necessary for activation of NF- B (Fig. 15). Accordingly, it is appreciated that a substance which binds competitively to Barxl to disturb direct binding between Barxl and Nkx3.2, would enhance the viability of chondrocytes by promoting NF- B activity. According to the present invention, a cell comprising the Barxl protein having the amino acid sequence of SEQ ID NO:4 is contacted to a substance of interest. Preferably, the Barxl protein of this invention exists as the form displayed on the cell surface, displayed on the virus (e.g., bacteriophage) surface, located intracellular^, isolated or purified.

Where the Barxl protein displayed on the cell surface or the virus surface, or located intracellularly is used, it is preferred that the Barxl protein is immobilized on the surface of the solid matrix for rapidity and automation of the screening process. It is also preferable for the isolated or purified Barxl protein to be immobilized on the solid matrix. The suitable matrix includes any material which can be used in the art the present invention pertains to. For example, the matrix includes hydrocarbon polymers such as polystyrene and polypropylene, glass, metals and gels, but not limited to. The solid matrix may be provided as the form of dipstick, microtiter plate, particle (e.g., bead), an affinity column and an immunoblot membrane (e.g., polyvinylidene fluoride membrane), protein chips or test tube, cuvette (see U.S. Pat. Nos. 5,143,825, 5,374,530, 4,908,305 and 5,498,551). Most preferably, the solid matrix is a microtiter plate.

The screening method of this invention may be performed by a diversity of methods known to the skilled artisan, especially by a high throughput method according to various binding assays.

According to the present invention, a substance of interest or the Barxl protein can be labeled by a detectable label. Said detectable label includes, but not limited to, chemical (e.g., biotin), enzyme label (e.g., horse radish peroxidase, alkaline phosphatase, peroxidase, luciferase, a-galactosidase and β-glucosidase), radio- isotope (e.g., C¹⁴ , I¹²⁵ , P³² and S³⁵), fluorescent [Coumarin, fluoresin, FITC (fluoresein Isothiocyanate), rhodamine 6G, rhodamine B, TAMRA (6-carboxy- tetramethyl-rhodamine), Cy-3, Cy-5, Texas Red, Alexa Fluor, DAPI (4,6-diamidino-2- phenylindole), HEX, TET, Dabsyl and FAM], chemiluminescent, FRET (fluorescence resonance energy transfer) and metal label {e.g. gold and silver) .

Where labeled substance of interest or labeled Barxl protein are used, the binding of substance of interest and the Barxl protein is measured by detecting signal derived from label. For examples, where alkaline phosphatase is used as label, color reaction substrates such as 5-Bromo-4-chloro-3-indolyl phosphate (BCIP) , nitro blue tetrazolium chloride (NBT), naphthol-AS-Bl-phosphate and enhanced chemifluorescence (ECF) are used to detect the signal.

Where horse radish peroxidase is used as label, substrates such as chloronaphthol, aminoethylcarbazole, diaminobenzidine, D-luciferin, Lucigenin (Bis- N-methylacridinium nitrate), resorufin benzyl ether, luminol, amplex red agent (10- acetyl-3,7-dihydroxyphenoxazine), HYR (p-phenylenediamine-HCI and pyrocatechol), tetramethylbenzidine (TMB), ABTS (2,2 '-Azine-di[3-ethylbenzthiazolinesulfonate]), o-phenylenediamine (OPD) and naphthol/pyronin are used to detect the signal.

The binding of the substance of interest and the Barxl protein may be analyzed without labeling of interactants. For example, a microphysiometer can be used to detect the interaction of the substance of interest with the Barxl protein. A microphysiometer is an analytical instrument that measures the rate at which a cell acidifies its environment using a light-addressable potentiometric sensor (LAPS). Changes in this acidification rate can be used as an indicator of the interaction between of the substance of interest and the Barxl protein (McConnell et al., Science 257: 19061912(1992)).

Such a determination may be accomplished using a technology such as realtime Biomolecular Interaction Analysis (BIA) (Sjolanderet al., 1991 Anal. Chem. 63:2338-2345 and Szabo et al., 1995 Curr. Opin. Struct. Biol. 5:699-705). "BIA" is a technology for studying biospecific interactions in real time, without labeling any of the interactants (e.g., BIAcore). Changes in the optical phenomenon of surface plasmon resonance (SPR) can be used as an indication of real-time reactions between biological molecules. The screening method of this invention may be performed according to two- hybrid assay or three hybrid assay (U.S. Pat. No. 5,283,317; Zervos et al., Cell 72, 223-232, 1993; Madura et al., J. Biol. Chem. 268, 1204612054, 1993; Bartel et al., Bio Techniques 14, 920924, 1993; Iwabuchi et al., Oncogene 8, 16931696, 1993; and W0 94/10300). In this case, the Barxl protein is used as a "bait" protein.

The two-hybrid system is based on the modular nature of most transcription factors, which consist of separable DNA-binding and activation domains. Briefly, the assay utilizes two different DNA constructs. In one construct, the gene that codes for the Barxl protein e.g., the nucleotide of SEQ ID NO:3) is fused to a gene encoding the DNA binding domain of a known transcription factor {e.g., GAL-4). In the other construct, a DNA sequence that encodes an unidentified protein ("prey" or "sample") is fused to a gene that codes for the activation domain of the known transcription factor. If the "bait" and the "prey" proteins interact, in vivo, forming a complex, the DNA-binding and activation domains of the transcription factor are brought into close proximity. This proximity allows transcription of a reporter gene (e.g., LacZ). Expression of the reporter gene can be detected to indicate that the protein of interest binds to the Barxl protein and thus could be used as a composition for treating arthritis.

The screening method of the present invention can be described with detailed examples as follows:

The representative exemplary method is carried out by phage display assay. It is analyzed whether the substance of interest binds to the Barxl protein which is displayed on the surface of the Barxl protein-encoding phage {e.g., 17) to screen a composition for treating arthritis.

According to a preferred embodiment, the method of this invention further comprises a step of treating a cell comprising the Barxl protein with the polypeptide having the amino acid sequence of SEQ ID NO:2 prior to the step (a). According to the present invention, SEQ ID NO: 2 is the the amino acid sequence of Nkx3.2 protein.

Concretely, before contacting a substance of interest to a cell comprising the Barxl protein, the Nkx3.2 protein which binds specifically to the Barxl protein is pre- treated. Afterwards, a substance of interest is treated and competitive binding of the substance of interest and the Nkx3.2 protein to the Barxl protein is analyzed. In case the substance which binds to the Barxl protein is treated in an excessive amount, the Nkx3.2 protein is dissociated from the Barxl protein

For facilitating the analysis, the Nkx3.2 protein can be labeled by a detectable label. Said detectable label includes, but not limited to, chemical {e.g., biotin), enzyme label {e.g., horse radish peroxidase, alkaline phosphatase, peroxidase, luciferase, a-galactosidase and β-glucosidase), radio-isotope {e.g., C¹⁴ , 1¹²⁵ , P³² and S³⁵), fluorescent [Coumarin, fluoresin, FITC (fluoresein Isothiocyanate), rhodamine 6G, rhodamine B, TA RA (6-carboxy-tetramethyl-rhodamine), Cy-3, Cy-5, Texas Red, Alexa Fluor, DAPI (4,6-diamidino-2-phenylindole), HEX, TET, Dabsyl and FAM], chemiluminescent, FRET (fluorescence resonance energy transfer) and metal label {e.g. gold and silver) .

Method of this invention can be performed by, for example, cytosol staining using Nkx3.2 protein-coumarin conjugate and stained cytosol may be observed by fluorescent microscope.

First, the Nkx3.2 protein-coumarin conjugate is treated to a cell containing the Barxl protein prior to the step (a). Subsequently, the substance of interest is treated to said cell in an excessive amount. When said cell stained by the Nkx3.2 protein- coumarin conjugate is decolorized, the substance is determined as the therapeutic drug candidate for treating arthritis.

Alternatively, the present invention can be embodied by treating the Nkx3.2 protein to a cell treated with a substance of interest, which contains the Barxl protein and then measuring the binding of the Nkx3.2 protein and the Barxl protein. According to a preferred embodiment, the cell of this invention is a chondrocyte.

According to a preferred embodiment, the method of this invention further comprises a step of treating a cell comprising the polypeptide having the amino acid sequence of SEQ ID NO:4 with the polypeptide having the amino acid sequence of SEQ ID NO:2 prior to the step (a).

According to a preferred embodiment, the arthritis of this invention is a degenerative arthritis. The features and advantages of the present invention will be summarized as follows:

(a) The present invention provides a composition for preventing or treating arthritis, a diagnosis kit for arthritis, a method for screening a composition for treating arthritis and a method for preventing or treating arthritis.

(b) The present invention accomplish the maintenance and survival of a chondrocyte which is essential for the function of connective tissue, therefore may be effectively used for preventing or treating arthritis fundamentally.

The present invention will now be described in further detail by examples. It would be obvious to those skilled in the art that these examples are intended to be more concretely illustrative and the scope of the present invention as set forth in the appended claims is not limited to or by the examples.

EXAMPLE 1: Nkx3.2

MATERIALS AND METHODS

Comparison of gene expression between epiphyseal plate chondrocytes and cartilage chondrocytes

Total RNA was isolated by dissecting epiphyseal plate from E16.5 mouse embryo, and the cDNA was synthesized. The cDNA was used as a template for detecting GAPDH and Nkx3.2 using PCR technique. In addition, total RNA was isolated from chondrocyte of human articular cartilage tissue, and the cDNA synthesized. The cDNA was used as a template for detecting GAPDH and Nkx3.2 using PCR technique.

The RT-PCR method used in this invention was performed as follows. Total RNA was isolated from the cell culture for each experiment using RNeasy kit (Qiagen) following the manufacturer's instructions. Five pg of total RNA was used to synthesize cDNA using cDNA synthesis kit (Invitrogen) following the manufacturer's instructions. The amount of mRNA of each gene was quantified and compared by using equal amounts of cDNA as template in PCR method.

The PCR reaction mixture consisted of IX Taq buffer (Invitrogen), 125 μΜ dNTP, 1 mM top primer, 1 mM bottom primer and 2X enhancer solution (Invitrogen), and 0.5 unit of Taq polymerase enzyme was used for each reaction.

Analyzing the changes in chondrocyte viability by RNA knockdown

The expression of Nkx3.2 gene in chondrocytes isolated from human articular cartilage tissue was infected with Nkx3.2 shRNA virus for gene knockdown.

The shRNA lentivirus solution used for the present invention was prepared as follows. The HEK293T cells (CRL-11268) purchased from ATCC was incubated in DMEM (with 10% FBS) medium without penicillin-streptomycin for 24 hrs to reach 60% of confluence. The cells were transfected with pLKO.l control vector (Openbiosystems Cat. No. RHS4080) or with human Nkx3.2 specific shRNA construct (Openbiosystems Cat. No. RHS4533-NM_001189/TRCN0000013602, hairpin sequence CCGGTCCAMGACCTAGAGGAGG CTCGAGTTCCTCCTCTAGGT nTGGAT 1 1 1 1 ). After one day, the culture medium was replaced with 10 ml of DMEM (with 10% FBS) medium containing penicillin-streptomycin. The supernatant was collected after incubating for 48 hrs for knockdown experiment. The cell culture used for RNA knockdown experiment has reached 60-70% of confluence on the day of the experiment. The cells were transfected with 1 ml of shRNA knockdown lentivirus mixed with 1 ml of penicillin-streptomycin containing DMEM (with 10% FBS) with 8 pg/rnl of polybrene. After 24 hrs, the culture medium was replaced with 1 ml of fresh DMEM (with 10% FBS) containing penicillin-streptomycin. The cell culture medium was used for analysis after incubating for another 24 hrs.

The level of cell death in cartilage chondrocytes, cartilage chondrocytes without the lentivirus infection and cartilage chondrocytes infected with pLKO control shRNA virus was monitored with CKX41 optical microscope (Olympus) at 40X or compared by FACS analysis.

The FACS analysis was performed as follows; 1) The cultured cells for TUNEL analysis were treated with trypsin (Invitrogen); 2) washed twice with PBS containing 5% fetal bovine serum and 0.09% NaN3; 3) washed once with IX Annexin-V binding buffer (BD Science) containing 10 mM HEPES (pH 7.4), 140 mM NaCI and 2.5 mM CaCI2; 4) cells reacted with Annexin-V-FITC (BD Science) for 20 min at room temperature in the binding buffer; and 5) the fluorescent labeled cells were quantitatively measured by using FACScaliber (BD Science).

Analysis ofNkx3.2 RNA expression in chondrocytes

Total RNA was isolated from chondrocyte of articular cartilage in normal and osteoarthritis patients, and the cDNA synthesized. The cDNA was used as a template for detecting GAPDH and Nkx3.2 using PCR technique. Total RNA was isolated from chondrocyte of human articular cartilage tissue, and the cDNA was synthesized. The cDNA was used as a template for detecting GAPDH and Nkx3.2 using PCR technique. The RT-PCR method is similar as described above.

Analysis of Nkx3.2 protein expression in chondrocytes

Total protein was isolated from articular cartilage chondrocytes of normal and osteoarthritis patients, and then Western blot analysis was performed against GAPDH and Nkx3.2. Western blot analysis was performed following the general procedure (8). The characteristic of each antibody is summarized below.

1) Anti-GAPDH : AbFrontier, Cat. No. LF-PA0018, dilution factor 1:5000, PBST with 2% milk

2) Anti-Nkx3.2 : AbCam, Cat No. ab56029, dilution factor 1:2000, TBST with 1% milk

Analysis of chondrocyte death in osteoarthritis patients

Chondrocyte viability in normal and osteoarthritis patients was compared by

FACS analysis using the level of binding with Annexin-V. NF-κΒ is activated by Nkx3.2 for chondrocyte survival; therefore the cells were treated with 10 mM of ΝΚ-κΒ activation inhibitor BAY 11-7086 (Calbiochem) to monitor further cell death. The FACS analysis was performed as described above.

Analyzing the cartilage tissue of lent/ irus overexpressing mouse

The possible application of Nkx3.2 in treating osteoarthritis was verified by using in vivo mouse model. For this purpose, an osteoarthritis induced mouse model was selected. The osteoarthritis mouse model was surgically induced via destabilization of the medial meniscus (DMM) of the knee (1). The overexpression of GFP or Nkx3.2 in cartilage tissue was induced by dropping 50 μΙ of lentivirus solution on the ligament transection site and incubating for 30 min at room temperature before suturing. Four weeks after DMM, the hind limb knee cartilage was removed for histological analysis. The lentivirus used for transfection was constructed from pLentiM1.4 backbone. The lentivirus solution used was 10⁶-10⁷ TU (Transduction unit)/ml. The viruses were ordered and purchased from Macrogen Ltd. Osteoarthritis was induced at 9-week-old mouse by DMM and infected with lentivirus overexpressing GFP or Nkx3.2. At 13 weeks old, the mouse hind limb cartilage section was stained with Safranin-0 (Sigma-Aldrich). RESULTS

Comparison of gene expression between epiphyseal plate chondrocyte and cartilage chondrocyte

The cDNA was synthesized from the total RNA isolated from chondrocytes of E16.5 mouse embryo epiphyseal plate and from human articular cartilage. PCR amplification was performed against GAPDH and Nkx3. When the expression level was quantified by using GAPDH expression level as the control, the level of Nkx3.2 in articular cartilage chondrocytes was significantly higher than those in epiphyseal plate chondrocyte (Fig. 4).

Change in chondrocyte viability by RNA knockdown

Chondrocyte isolated from human articular cartilage was infected with human Nkx3.2 shRNA virus for the knockdown of the gene (Fig. 5). A significant reduction in chondrocyte cell survival was observed in the Nkx3.2 knockdown group compared to non-infected group and pLKO control shRNA virus infected group from microscopic analysis (Fig.6) and FACS analysis. This result proves that Nkx3.2 is critically related to the survival of articular cartilage

Nkx3.2 RNA expression

Total RNA was isolated from chondrocytes of normal and osteoarthritis patients. PCR amplification performed against GAPDH and Nkx3.2 showed significantly lower amount of Nkx3.2 mRNA expression in chondrocytes of osteoarthritis patients when GAPDH expression level was used as a quantitative control (Fig. 8). This result is similar to that of the previous knockdown experiment, suggesting that the reduction of Nkx3.2 expression by the onset of osteoarthritis inhibited the cell survival of chondrocytes. This also suggests a possible application of Nkx3.2 as a novel biomarker for osteoarthritis.

Nkx3.2 protein expression

Western blot analysis for GAPDH and Nkx3.2 was performed using chondrocytes isolated from normal and osteoarthritis patient articular cartilages. When the expression level was quantified by using GAPDH expression level as the control, significantly lower expression of Nkx3.2 protein was observed in osteoarthritis patients compared to the normal group (Fig. 9). Chondrocyte cell death in osteoarthritis patients

When the cell viability of chondrocytes was analyzed by measuring the level of interaction with Annexin-V, higher level of cell death was detected in osteoarthritis patients (24.3%) compared to the normal group (5.15%)(Rg. 10). In addition, when monitored for cell death after treating with BAY 11-7085, a significantly higher level of cell death of chondrocytes was observed in osteoarthritis patients (68.11%), compared to the normal group (19.93%) (Fig. 10).

Analyzing the cartilage tissue of lent/Virus overexpressing mouse

Cartilage tissues from mouse without surgery, mouse with DMM infected with GFP overexpressing lentivirus and mouse with DMM infected with Nkx3.2 overexpressing lentivirus were stained with Safranin-O. The result showed significant level of protection of cartilage tissue loss in Nkx3.2 overexpressing mouse compared to the GFP overexpressing control mouse (Fig. 11). This result suggests that when the loss of Nkx3.2 expression by the pathogenesis of osteoarthritis is artificially recovered, the progression of the osteoarthritis can be effectively regulated.

EXAMPLE 2 : Barxl

METHODS Inhibition of Ι-κΒ protein ubiquitination by Barxl

Nkx3.2 ubiquitinates Ι-κΒ protein to activate NF- κΒ (1), therefore immunoprecipitation experiment was performed to analyze whether Barxl can inhibit

NF-KB activation by inhibiting the ubiquitination process of Nkx3.2.

I-KB overexpression was induced by transient transfection of 3-6 mg (per plOO plate) of expression plasmid having pCS2 backbone into ATDC5 chondrocyte cell line (3) using FuGene6 (Roche) according to manufacturer's instructions.

Immunoprecipitation was performed by using anti-Myc antibody (Upstate

Biotechnology) to detect the Myc-tag labeled on Ι- Β according to the method published by the present inventors (Park, M., Yong, Y., Choi, S.W., Kim, J.H., Lee,

J.E., and Kim, D.W. Constitutive RelA activation mediated by Nkx3.2 controls chondrocyte viability. Nat. Cell Biol. 9:287-298(2007)).

Western blot experiment was performed to detect the level of ubiquitination in the immunoprecipitated Ι-κΒ protein by using anti-Flag antibody to detect the Flag-tag. Western blot analysis was performed following the general procedure

(Harlow E., and Lane D. In: Antibodies: A Laboratory Manual, Cold Spring Harbor

Laboratory Press, Cold Spring Harbor, New York (1988)). The characteristic of each antibody is summarized below :

1) Anti-GAPDH : AbFrontier, Cat. No. LF-PA0018, dilution factor 1:5000, PBST with 2% milk

2) Anti-Barxl : AbCam, Cat No. ab26156, dilution factor 1:2000, TBST with 1% milk

Inhibition of Nkx3.2 and I-kB complex formation by the interaction of Barxl and Nkx3.2

Protein overexpression was induced by transient transfection of 3-6 mg (per plOO plate) of each expression plasmid having pCS2 backbone into ATDC5 chondrocyte cell line (3) using FuGene6 (Roche). An immunoprecipitation experiment was performed using anti-Myc antibody (Upstate Biotechnology) to detect the Myc- tag labeled on Nkx3.2. In addition, a Western blot experiment was performed to detect the amount of Ι-κΒ protein co-immunoprecipitated with Nkx3.2 by using anti- Flag antibody that recognizes the Flag-tag according to the method described above.

Transcription activation ofNF-κΒ by Barxl

Protein overexpression was induced by transient transfection of 100-200 ng (per 12-well plate) each of the expression plasmid having pCS2 backbone into ATDC5 chondrocyte cell line (3) using FuGene6 (Roche). The level of transcriptional activation was analyzed by using 4X-KB-LUC reporter, that has 4 repeats of NF-KB specific DNA binding sites (Park, M, Yong, Y., Choi, S.W., Kim, J.H., Lee, J.E., and Kim, D.W. Constitutive RefA activation mediated by !Mkx3.2 controls chondrocyte viability. Nat. Cell Biol. 9:287-298(2007)).

Change in chondrocyte viability by Barxl overexpression

Barxl overexpression was induced by transient transfection of 5 mg (per plOO plate) of the expression plasmids with pCol2 backbone into ATDC5 chondrocyte cell line (3) using FuGene6 (Roche). The chondrocyte viability was analyzed by measuring the binding level with Annexin-V. The lentivirus used for transduction was constructed by using the pLentiM1.4 backbone. The lentivirus solution used was 10⁶- 10⁷ TU (transduction unit)/ml. The viruses were ordered and purchased from Macrogen Ltd.

The FACS analysis was performed as follows; 1) The cultured cells for TUNEL analysis were treated with trypsin (Invitrogen); 2) washed twice with PBS containing 5% fetal bovine serum and 0.09% NaN₃; 3) washed once with IX Annexin-V binding buffer (BD Science) containing 10 mM HEPES (pH 7.4), 140 mM NaCI and 2.5 mM CaCI₂; 4) cells were reacted with Annexin-V-FITC (BD Science) for 20 min at room temperature in the binding buffer; and 5) the fluorescent labeled cells were quantitatively measured by using FACScaliber (BD Science).

For TUNEL analysis, the cell medium was fixed with 2% paraform aldehyde. Cell membrane permeabilization was performed with the solution containing 0.1% sodium citrate and 0.1% Triton-X-100. Apoptosis was detected using an In Situ Cell Death Detection Kit (Roche) according to the manufacturer's instructions.

Change in chondrocyte viability by Barxl knockdown

To investigate the effect of Barxl knockdown on inhibiting chondrocyte cell death, the viability of ATDC5 chondrocyte where Barxl expression was specifically inhibited was analyzed through the binding with Annexin-V.

The shRNA lentivirus solution used for Barxl RNA knockdown was prepared as follows. The HEK293T cells (CRL-11268) purchased from ATCC was incubated in DMEM medium without penicillin-streptomycin (containing 10% FBS) for 24 hrs to reach 60% of confluence. The cells were transfected with pLKO.l control vector (Openbiosystems Cat. No. RHS4080) or with human Barxl specific shRNA construct (Openbiosystems Cat. No. RHS3979-9584168, hairpin sequence: CCGGCGGCCCAAGAAGAACTCAATTCTCGAGAATTGAGTTC I I J I I GGGCCG I I I I I ). After one day, the culture medium was replaced with 10 ml of DMEM (with 10% FBS) medium containing penicillin-streptomycin. The supernatant was collected after 48 hrs of incubation to be used for knockdown experiment. The cell culture used for RNA knockdown experiment reached 60-70% of confluence on the day of the experiment. The cells were transfected with 1 ml of shRNA knockdown lentivirus mixed with 1 ml of penicillin-streptomycin containing DMEM (with 10% FBS) added with 8 pg/rnl of polybrene. After 24 hrs, the culture medium was replaced into 1 ml of penicillin-streptomycin containing fresh DMEM (with 10% FBS). The cell culture medium was used for analysis after incubating for another 24 hrs. Analysis of Barxl expression in osteoarthritis patients

Total protein was isolated from chondrocytes of articular cartilage in normal and osteoarthritis patients, then Western blot analysis was performed against GAPDH and Barxl according to method described above.

Chondrocytes cell death analysis in osteoarthritis patients

The cell viability of chondrocytes from normal and osteoarthritis patients were analyzed by comparing the binding with Annexin-V using FACS analysis as described previously.

RESULTS

Inhibition of Ι-κΒ protein ubiquitination by Barxl

According to the fact that Nkx3.2 and Barxl has complementary expression profiles in cartilage tissue during the embryonic development (Fig. 12), Barxl was considered as the target for arthritis treatment. As a result, the present inventor has proved for the first time that Barxl is involved in regulation of chondrocyte death. First, the present inventor confirmed the effective inhibiting role of Barxl in Ι-κΒ ubiquitination, which is induced by Nkx3.2 that leads to the activation of NF-κΒ (Fig. 13). Second, transcriptional activation of NF- κΒ (1) induced by Nkx3.2 was shown to be significantly inhibited by Barxl (Fig. 14). These results prove that Barxl in a substance which effectively inhibits the role of Nkx3.2 in activating NF-KB.

Inhibition of Nkx3.2 and I-kB complex formation by the interaction of Barxl and Nkx3.2

Immunoprecipitation with anti c-Myc antibody showed that the interaction between Nkx3.2 and Ι-κΒ, critical for NF-κΒ (1) activation was blocked by the direct protein binding between Barxl and Nkx3.2. As shown in Fig. 15, overexpression of Barxl significantly inhibited the protein interaction between Nkx3.2 and Ι-κΒ. In addition, Fig. 16 showed that when Nkx3.2, 1-κΒ and Barxl coexisted, the interaction between Nkx3.2 and Barxl occurred prior to the interaction between Nkx3.2 and I- KB. This provided an understanding of the results represented in Fig. 13 and Fig. 14 in molecular levels.

Change in chondrocyte viability by Barxl overexpression and knockdown

The results showed positive evidence that there was a relationship in regulating chondrocyte cell death. Chondrocytes overexpressing Barxl showed higher level of cell death compared to the control vector group, indicating that overexpression of Barxl induces chondrocyte death (Fig. 16). Chondrocyte with inhibited Barxl expression by RNA knockdown experiment showed a 50-70% reduction of cell death (Fig. 17). These results suggest that the balance between activation of Barxl in inducing chondrocyte death and activation of Nkx3.2 in inhibiting chondrocyte death is critically related in chondrocyte survival.

Barxl expression in osteoarthritis patients

The indication that the function of Barxl in regulating chondrocyte death is directly related to osteoarthritis was confirmed by Western blot analysis. The result showed a significant increase of Baxl expression in chondrocytes isolated from osteoarthritis patient tissues compared to normal group (Fig. 18). This result coincides with the previous result from Barxl overexpression experiment. This is an important finding indicating that the increased expression of Barxl during the onset of osteoarthritis inhibited chondrocyte survival. This finding also suggests a possible application of Barxl as a novel biomarker for osteoarthritis.

Chondrocyte cell death in osteoarthritis patients

In additional experiments to support this finding, the FACS analysis data by measuring the level of Annexin-V binding showed a higher level of cell death in chondrocytes isolated from osteoarthritis patient cartilage compared to normal group (Fig.19). The result showed significantly higher level of cell death in chondrocytes of osteoarthritis patients after treating with BAY 11-7085, an activation inhibitor of NK- KB (1) that is activated by Nkx3.2 for chondrocyte survival (Fig. 19). These results suggest that the activation of chondrocyte death induced by the increased level of Barxl expression with the onset of osteoarthritis is closely related to the inhibitory function of Nkx3.2 on chondrocyte death, as well as the progression of the osteoarthritis.

References

] 1. Glasson, S.S. et al. Deletion of active ADAMTS5 prevents cartilage degradation in a murine model of osteoarthritis. Nature 434:644648 (2005).

2. Li, Q., Withoff, S., and Verma, LM. Inflammation-associated cancer: NF-kappaB is the lynchpin. Trends Immunol. 26:318-325 (2005).

3. Meffert, M.K., and Baltimore, D. Physiological functions for brain NF-kappaB. Trends Neurosci. 28:37-43 (2005).

4. Vallabhapurapu, S., and Karin, M. Regulation and function of NF-kappaB transcription factors in the immune system. Annu. Rev. Immunol. 27:693-733(2009). 5. Chen, Z., Hagler, J., Palombella, V.J., Melandri, F., Scherer, D., Ballard, D., and Maniatis, T. Signal-induced site-specific phosphorylation targets I kappa B alpha to the ubiquitin-proteasome pathway. Genes Dev. 9:1586-1597 (1995).

6. Hayden, M.S., and Ghosh, S. Signaling to NF-kappaB. Genes Dev. 18:2195-2224 (2004).

7. Park, M., Yong, Y, Choi, S.W., Kim, J.H., Lee, J.E., and Kim, D.W. Constitutive RelA activation mediated by Nkx3.2 controls chondrocyte viability. Nat. Cell Biol. 9:287- 298 (2007).

8. Harlow E., and Lane D. In: Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York (1988).

9. Park, M., Yong, Y, Choi, S.W., Kim, J.H., Lee, J.E., and Kim, D.W. Constitutive RelA activation mediated by Nkx3.2 controls chondrocyte viability. Nat. Cell Biol. 9:287- 298 (2007).

10. Vicki Church, V., Yamaguchi, K., Tsang, P., Akita, K., Logan, C, Francis-West, P. Expression and function of Bapxl during chick limb development. Anat. Embryol. 209: 461469 (2005).

11. Atsumi, T., Miwa, Y, Kimata, K. & Ikawa, Y. A chondrogenic cell line derived from a differentiating culture of AT805 teratocarcinoma cells. Cell Differ. Dev. 30: 109-16 (1990).

12. Harlow E., and Lane D. In: Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York (1988).

Claims

What is claimed is:

1. A composition for preventing or treating arthritis, comprising a polypeptide having the amino acid sequence of SEQ ID NO:2.

2. A composition for preventing or treating arthritis, comprising a nucleotide sequence encoding the amino acid sequence of SEQ ID NO:2.

3. The composition according to claim 2, wherein the nucleotide sequence comprises the nucleotide sequence of SEQ ID NO: l.

4. The composition according to claim 3, wherein the nucleotide sequence is contained in a gene delivery system.

5. The composition according to any one of claims 1 to 4, wherein the arthritis is a degenerative arthritis.

6. A diagnosis kit for arthritis, comprising an antibody or an aptamer which specifically binds to a polypeptide having the amino acid sequence of SEQ ID NO:2.

7. A diagnosis kit for arthritis, comprising a primer or a probe which specifically binds to a nucleotide sequence encoding the amino acid sequence of SEQ ID NO:2.

8. The diagnosis kit according to claim 7, wherein the nucleotide sequence comprises the nucleotide sequence of SEQ ID NO: l.

9. The diagnosis kit according to any one of claims 6 to 8, wherein the arthritis is a degenerative arthritis.

10. The diagnosis kit according to any one of claims 6 to 8, wherein the low expression level of the nucleotide sequence or the polypeptide is indicative of increased risk of arthritis in a subject.

11. A method for screening a therapeutic drug candidate for treating arthritis, comprising the steps of:

(a) contacting a substance of interest to a cell comprising the nucleotide sequence of SEQ ID NO:l; and

(b) measuring the expression level of the nucleotide sequence of SEQ ID NO: l, wherein when the expression level of the nucleotide sequence of SEQ ID NO: l is increased, the substance is determined as the therapeutic drug candidate for treating arthritis.

12. The method according to claim 11, wherein the cell is a chondrocyte.

13. The method according to claim 11, wherein the arthritis is a degenerative arthritis.

14. A composition for preventing or treating arthritis, comprising an agent to increase the expression level of the nucleotide sequence of SEQ ID NO: l.

15. A composition for preventing or treating arthritis, comprising an agent to increase the activity of a polypeptide having the amino acid sequence of SEQ ID NO:2

16. A method for preventing or treating arthritis, which comprises administering to a subject the composition according to claim 1 or 2.

17. A composition for preventing or treating arthritis, comprising a nucleic acid molecule suppressing the expression level of the nucleotide sequence encoding the amino acid sequence of SEQ ID NO:4.

18. The composition according to claim 17, wherein the nucleotide sequence comprises the nucleotide sequence of SEQ ID NO:3.

19. The composition according to claim 17, wherein the nucleic acid molecule is shRNA, siRNA, miRNA, ribozyme, PNA (peptide nucleic acid) or antisense oligonucleotide.

20. The composition according to claim 19, wherein the nucleic acid molecule is shRNA.

21. The composition according to any one of claims 17 to 20, wherein the nucleic acid molecule is contained in a gene delivery system.

22. The composition according to any one of claims 17 to 20, wherein the arthritis is a degenerative arthritis.

23. A diagnosis kit for arthritis, comprising an antibody or an aptamer which specifically binds to a polypeptide having the amino acid sequence of SEQ ID NO:4.

24. A diagnosis kit for arthritis, comprising a primer or a probe which specifically binds to a nucleotide sequence encoding the amino acid sequence of SEQ ID NO:4.

25. The diagnosis kit according to claim 24, wherein the nucleotide sequence comprises the nucleotide sequence of SEQ ID NO:3.

26. The diagnosis kit according to any one of claims 23 to 25, wherein the arthritis is a degenerative arthritis.

27. The diagnosis kit according to any one of claims 23 to 25, wherein a subject with high expression level of said nucleotide or said polypeptide has increased risk of arthritis.

28. A method for screening a composition for treating arthritis, comprising the steps of:

(a) contacting a substance of interest to a cell comprising the nucleotide sequence of SEQ ID NO:3; and

(b) measuring the expression level of the nucleotide sequence of SEQ ID IMO:3, wherein when the expression level of the nucleotide sequence of SEQ ID NO:3 is decreased, the substance is determined as the therapeutic drug candidate for treating arthritis.

29. A method for screening a composition for treating arthritis, comprising the steps of:

(a) contacting a substance of interest to a cell comprising the polypeptide having the amino acid sequence of SEQ ID NO:4; and

(b) analyzing the binding of said polypeptide and the substance of interest, wherein when the binding of said polypeptide and the substance of interest is increased, the substance is determined as the therapeutic drug candidate for treating arthritis.

30. The method according to any one of claims 28 to 30, wherein the cell is a chondrocyte.

31. The method according to claim 29, wherein the method further comprises the step of treating a cell comprising the polypeptide having the amino acid sequence of SEQ ID NO:4 with the polypeptide having the amino acid sequence of SEQ ID NO:2 prior to the step (a).

32. The method according to any one of claims 28 to 30, wherein the arthritis is a degenerative arthritis.