NKX3.2-FRAGMENT AND PHARMACEUTICAL COMPOSITION, USING IT AS AN ACTIVE INGREDIENT

Description

Technical Field

[0001] The present invention relates to an Nkx3.2 fragment with improved stability under a pathological tissue environment of arthritis.Background Art

[0002] Degenerative arthritis, which is one of the most commonly occurring arthritis, is a disease in which degenerative changes damage cartilage tissues that protect a joint, bones and ligaments that form a joint, and the like, thereby resulting in inflammation and pain. Conventionally, treatment of degenerative arthritis has been carried out primarily through control of inflammation. However, it has been proven that the control of inflammation cannot be a fundamental therapeutic technique.

[0003] Therefore, in order to treat the cause of degenerative arthritis, identification of a target that regulates processes, such as generation, differentiation, death, calcification of chondrocytes and development of methods to control the target are required.

[0004] Meanwhile, overexpressed Nkx3.2 (NK3 homeobox 2) has been shown to suppress loss of cartilage tissue caused by degenerative arthritis, and thus the protein may be used for treatment of degenerative arthritis. In this regard, Korean Patent No. 10-1150900 describes a composition for treating arthritis, an arthritis diagnostic kit, or a method of screening a therapeutic agent for arthritis using Nkx3.2 protein. WO2011 / 093647 also relates to a composition for preventing or treating arthritis using Nkx3.2 protein.

[0005] In addition, it has been shown that degradation of Nkx3.2 protein is promoted by the Indian Hedgehog (Ihh) signaling, which is activated during the process of hypertrophy and calcification of chondrocytes, and this phenomenon is mediated by a proteolytic enzyme, Siah1. Furthermore, it has been shown that the Indian Hedgehog signaling increases with development of degenerative arthritis accompanied by chondrocyte calcification, and controlling the Indian Hedgehog signaling suppresses the progression of degenerative arthritis in animal models.Detailed Description of the InventionTechnical Problem

[0006] The present inventors conducted studies to develop therapeutics for degenerative arthritis using Nkx3.2 variants that can effectively function under the pathological environment of degenerative arthritis. Consequently, the present inventors produced Nkx3.2 fragments that are resistant to proteolysis induced by Siah1. The present inventors also identified that the aforementioned Nkx3.2 fragments can induce NF-κB activation at the level comparable to the full-length Nkx3.2. Furthermore, the present inventors found that the Nkx3.2 fragments exhibit remarkably improved therapeutic efficacy against degenerative arthritis as compared to the full-length Nkx3.2.Solution to Problem

[0007] In order to achieve the above objects, the present invention provides a polypeptide consisting of the amino acid sequence of SEQ ID NO: 9, 10, 12, 13, 14, 17, 20, 21, 22, 23, 24, 25, 26, 27, or 28.

[0008] Furthermore, the present invention provides polynucleotides encoding the aforementioned polypeptides.

[0009] In addition, the present invention provides expression vectors comprising the aforementioned polynucleotides.

[0010] Furthermore, the present invention provides host cells harboring the aforementioned expression vectors.

[0011] Furthermore, the present invention provides recombinant viruses comprising the aforementioned polynucleotides.Advantageous Effects of Invention

[0012] The Nkx3.2 fragments of the present invention have the function of activating NF-κB at the level comparable to the full-length Nkx3.2 and are resistant to proteolysis mediated by Siah1. In addition, the aforementioned Nkx3.2 fragments exhibit improved therapeutic effects against degenerative arthritis as compared with the full length Nkx3.2 in animal model-based in vivo efficacy evaluation. Thus, the Nkx3.2 fragments can be effectively used for preventing or treating arthritis.Brief Description of Drawings

[0013] FIG. 1 is photographic illustration showing the resistance of Nkx3.2 fragments against proteolysis mediated by Siah1. FIG. 2 is photographic illustration showing the binding of Nkx3.2 fragments to IκBα. FIG. 3 is photographic illustration showing induction of degradation of IκBα by NKx3.2 fragments. FIG. 4 is a graph showing activation of the transcriptional activity of NF-κB by NKx3.2 fragments. FIG. 5 is a schematic diagram depicting the molecular mechanism underlying the NF-κB activation process induced by Nkx3.2. FIG. 6 is a schematic diagram for the animal experiment procedure for evaluation of the therapeutic effect of Nkx3.2 fragments using a degenerative arthritis-induced animal model. FIG. 7 is photographic illustration showing histopathological evaluation of the therapeutic efficacy against degenerative arthritis of Nkx3.2 or Nkx3.2 fragments expressed in the affected areas. FIG. 8 is a graph showing the severity of degenerative arthritis on a scale of 0 to 5 based on quantitative evaluation of overall data obtained through histological analysis. Best Mode for Carrying out the Invention

[0014] Hereinafter, the present invention will be described in detail.

[0015] The present invention provides a polypeptide consisting of the amino acid sequence of SEQ ID NO: 9, 10, 12, 13, 14, 17, 20, 21, 22, 23, 24, 25, 26, 27, or 28.

[0016] In some of the Nkx3.2 fragments of the invention, the polypeptide may be represented by the following Formula (I):         N-terminal extension domain-core domain-C-terminal extension domain     (I), in the above formula (I) the core domain is a polypeptide comprising the amino acid sequence of SEQ ID NO: 1; the N-terminal extension domain is a polypeptide comprising the amino acid sequence of SEQ ID NO: 35 in which 1 to 53 amino acids are consecutively deletable from the N-terminus to the C-terminal direction, starting from the amino acid at position 1 of SEQ ID NO: 35; and the C-terminal extension domain is a polypeptide comprising the amino acid sequence of SEQ ID NO: 5 in which 1 to 23 amino acids are consecutively deletable from the C-terminus to the N-terminal direction, starting from the amino acid at position 24 of SEQ ID NO: 5.

[0017] The core domain is a polypeptide comprising the amino acid sequence from position 166 to position 309 of the full-length Nkx3.2 protein.

[0018] The N-terminal extension domain is a domain bound to the N-terminus of the above-mentioned core domain, and is a polypeptide comprising the amino acid sequence from position 112 to position 165 of the full-length Nkx3.2 protein.

[0019] The C-terminal extension domain is a domain bound to the C-terminus of the above-mentioned core domain, and is a polypeptide comprising the amino acid sequence from positions 310 to 333 of the full-length Nkx3.2 protein.

[0020] Alternatively, some of the Nkx3.2 fragments of the invention may be represented by the following Formula (II):         N-terminal extension domain-core domain-C-terminal extension domain     (II), in the above Formula (II), the core domain is a polypeptide comprising the amino acid sequence of SEQ ID NO: 37; the N-terminal extension domain is a polypeptide comprising the amino acid sequence of SEQ ID NO: 39 in which 1 to 41 amino acids are consecutively deletable from the N-terminus to the C-terminal direction, starting from the amino acid at position 1 of SEQ ID NO: 39; and the C-terminal extension domain is a polypeptide comprising the amino acid sequence of SEQ ID NO: 41 in which 1 to 15 amino acids are consecutively deletable from the C-terminus to the N-terminal direction, starting from the amino acid at position 16 of SEQ ID NO: 41. The core domain is a polypeptide comprising the amino acid sequence from position 154 to position 317 of the full-length Nkx3.2 protein.

[0021] The N-terminal extension domain is a domain bound to the N-terminus of the above-mentioned core domain, and is a polypeptide comprising the amino acid sequence from position 112 to position 153 of the full-length Nkx3.2 protein.

[0022] The C-terminal extension domain is a domain bound to the C-terminus of the above-mentioned core domain, and is a polypeptide comprising the amino acid sequence from position 318 to position 333 of the full-length Nkx3.2 protein.

[0023] Specifically, the polypeptides of the invention consist of the amino acid sequence of SEQ ID NO: 9, 10, 12, 13, 14, 17, 20, 21, 22, 23, 24, 25, 26, 27, or 28.

[0024] The polypeptides of the invention represented by the above Formula (I) or (II) are fragments of the Nkx3.2 protein and are not naturally present in living bodies. Nevertheless, the polypeptides are not easily degraded in vivo while having the activity comparable to the full-length Nkx3.2 protein, and thus can stay present in a body longer than the full-length Nkx3.2, exhibiting an excellent activity.

[0025] The present invention provides polynucleotides encoding the polypeptides consisting of the amino acid sequence of SEQ ID NO: 9, 10, 12, 13, 14, 17, 20, 21, 22, 23, 24, 25, 26, 27, or 28.

[0026] The polynucleotides according to the present invention may encode the core domain, the N-terminal extension domain, and the C-terminal extension domain which may include, respectively, the nucleotide sequences of SEQ ID NO: 2 or 38, SEQ ID NO: 36 or 40, and SEQ ID NO: 6 or 42.

[0027] The polynucleotide may include a polynucleotide substituted with another nucleotide sequence that expresses the polypeptide of SEQ ID NO: 1, SEQ ID NO: 35, or SEQ ID NO: 5.

[0028] The polynucleotide may include a polynucleotide substituted with another nucleotide sequence that expresses the polypeptide of SEQ ID NO: 37, SEQ ID NO: 39, or SEQ ID NO: 41.

[0029] The present invention provides expression vectors comprising the polynucleotides.

[0030] The expression vector may be a plasmid vector, a cosmid vector, a bacteriophage vector, or a viral vector. The expression vector can be constructed by a person of ordinary skill in the art, such that the polynucleotides according to the present invention can be expressed and secreted therein.

[0031] In addition, the present invention provides host cells harboring the expression vectors.

[0032] The host cell is a cell transfected with an expression vector comprising the polynucleotide according to the present invention, and may be a prokaryotic cell or a eukaryotic cell. Specifically, the host cell may be a mammalian cell. The transfection can be carried out using the methods known in the art. Meanwhile, an example of the prokaryotic cell may be E. coli, and an example of the eukaryotic cell may be yeast. In addition, the mammalian cell may be NS / 0 myeloma cells, 293 cells, Chinese hamster ovary cells (CHO cells), HeLa cells, CapT cells (human amniotic fluid-derived cells), or COS cells.

[0033] The present invention provides recombinant viruses comprising the polynucleotides provided herein.

[0034] The virus may be any one selected from the group consisting of an adenovirus, an adeno-associated virus (AAV), a retrovirus, a lentivirus, a herpes simplex virus, and a vaccinia virus. Specifically, the virus may be an adeno-associated virus (AAV). The adeno-associated virus is not limited to a specific serotype, and in some embodiments, the AAV may be any one of AAV1 to AAV9.

[0035] Since the adeno-associated virus (AAV) is capable of infecting non-dividing cells and has an ability to infect various types of cells, the adeno-associated virus is suitably used as a gene delivery system of the present invention. Details for preparation and uses of AAV vectors are described, for example, in U.S. Patent Nos. 5,139,941 and 4,797,368.

[0036] Typically, the AAV can be produced by co-transfection of a plasmid comprising a gene sequence of interest which is flanked by two AAV terminal repeats and an expression plasmid comprising a wild-type AAV coding sequence that does not include the terminal repeats.

[0037] In embodiments of the present invention, the present inventors produced Nkx3.2 fragments, and found that the fragments are not degraded by Siah1 (FIG. 1). The inventors also found that NKx3.2 fragments provided herein induce the degradation of IκBα through binding to IκBα (FIGS. 2 and 3) and induce transcriptional activation of NF-κB (FIG. 4). In addition, the present inventors found that when the adeno-associated virus that includes the polynucleotide encoding the Nkx3.2 fragment is administered to degenerative arthritis-induced mice, damaged cartilage tissue is restored (FIGS. 7 and 8). Therefore, the Nkx3.2 fragments of the present invention can be effectively used for preventing or treating arthritis.

[0038] The Nkx3.2 fragment can be obtained by a host cell transfected with an expression vector that includes a polynucleotide encoding the polypeptide consisting of the amino acid sequence of SEQ ID NO: 9, 10, 12, 13, 14, 17, 20, 21, 22, 23, 24, 25, 26, 27, or 28.

[0039] The arthritis may be any one selected from the group consisting of osteoarthritis, rheumatoid arthritis, degenerative arthritis, gouty arthritis, juvenile arthritis, senescent arthritis, reactive arthritis, and combinations thereof.

[0040] The polypeptide or recombinant virus of the invention may be used as an active ingredient in a pharmaceutical composition for preventing or treating arthritis.

[0041] A recombinant virus that includes a polynucleotide encoding the Nkx3.2 fragment can be obtained through a host cell transfected with an expression vector that includes a polynucleotide consisting of the amino acid sequence of SEQ ID NO: 9, 10, 12, 13, 14, 17, 20, 21, 22, 23, 24, 25, 26, 27, or 28.

[0042] The subject to be treated may be a mammal, in particular, a human. The route of administration can be appropriately selected by a person skilled in the art in consideration of an administration method, volume and viscosity of body fluid, and the like. Specifically, the pharmaceutical composition may be intra-articularly administered.

[0043] The pharmaceutical composition may be intra-articularly administered. As used herein, the term "intra-articularly" means that administration is carried out via a lumen enclosed by an articular capsule, which is a gap between bones in a joint. There are various methods to carry out intra-articular administration. For example, there is a method in which a patient is asked to bend one knee 90 degrees in a state of lying down at a posture looking at the ceiling, and a syringe is intra-articularly inserted. In this posture, the inside and the outside joint boundaries can be relatively easily distinguished by hand. Injection can be carried out at either or both of the inside and the outside joint boundaries, and is mostly carried out toward the inside joint boundary. In addition, there is also a method of carrying out injection at a posture where a knee is stretched. For both postures, when the syringe is correctly inserted into a predetermined injection site, the injection solution may be injected with little resistance. However, when, at the time of pressing a syringe, drugs do not enter well, and a sense of resistance is recognized or a patient complains of severe pain, the injection site of the syringe should be adjusted.

[0044] Nkx3.2 fragments of the invention with increased stability in a body may be produced by deleting any one region of a polypeptide comprising the amino acid sequence of SEQ ID NO: 7, which is selected from the group consisting of an N-terminal region and a C-terminal region, and a combination thereof.

[0045] Deletion of the N-terminal region may be such that 1 to 165 amino acids are consecutively deleted from the N-terminus to the C-terminal direction, starting from the amino acid at position 1 of SEQ ID NO: 7. Specifically, the deletion may be such that 1 to 53 amino acids are consecutively deleted from the N-terminus to the C-terminal direction, starting from the amino acid at position 112 of SEQ ID NO: 7. The deletion of the N-terminal region may be such that 11, 18, 38, 41, 44, 47, 50, or 53 amino acid residues are deleted from the N-terminus to the C-terminal direction, starting from the amino acid at position 112 of SEQ ID NO: 7.

[0046] Deletion of the C-terminal region may be such that 1 to 23 amino acids are consecutively deleted from the C-terminus to the N-terminal direction, starting from the amino acid at position 333 of SEQ ID NO: 7. The deletion of the C-terminal region may be such that 13, 15, 17, 19, 21, or 23 amino acid residues are deleted from the C-terminus to the N-terminal direction, starting from the amino acid at position 333 of SEQ ID NO: 7.

[0047] The deletion of the amino acid residue may occur at either or both of the N-terminal region and the C-terminal region. In accordance with the present invention, the Nkx3.2 fragment that is produced consists of the amino acid sequence of SEQ ID NO: 9, 10, 12, 13, 14, 17, 20, 21, 22, 23, 24, 25, 26, 27, or 28.

[0048] The deletion of the amino acid residues can be carried out with an appropriate method by a person skilled in the art. The Nkx3.2 fragments with increased stability in a body produced by the above method are not easily degraded in vivo by Siah1, and thus may be present in a body longer than the wild type Nkx3.2 protein.Modes for Carrying Out the Invention

[0049] Hereinafter, the present invention will be described in detail by the following examples, which are intended to illustrate the present invention. The scope of the invention is as set out in the appended claims.Example 1. Construction of vectors expressing Nkx3.2 fragments

[0050] In order to obtain variants which are resistant to proteolysis mediated by Siah1, vectors expressing Nkx3.2 fragments were constructed by the following method.

[0051] Specifically, the Nkx3.2 gene having the nucleotide sequence represented by SEQ ID NO: 8 was used as a template and amplified using a Lamp Pfu DNA polymerase (Cat. # LP116-250, BIOFACT Co., Ltd., Korea) according to the manufacturer's protocol. Each of the amplified PCR products was cleaved with restriction enzymes EcoRI (Cat. # FD0274, Thermo Fisher Scientific Inc., USA), and XhoI (Cat. # FD0694, Thermo Fisher Scientific Inc., USA) or XbaI (Cat. # FD0684, Thermo Fisher Scientific Inc., USA), and respectively, inserted into a pCS expression vector (Addgene Cat # 17095) using a T4 ligase (Cat. # EL0011, Thermo Fisher Scientific Inc., USA).

[0052] Consequently, expression vectors expressing 20 kinds of Nkx3.2 fragments were constructed as shown in Table 1 below. [Table 1]NameFeatureSEQ ID NONkx3.2 (1-333)Full-length Nkx3.2SEQ ID NO:7Nkx3.2 (1-320)Nkx3.2 fragment containing 1st to 320th amino acidsSEQ ID NO:9Nkx3.2 (1-307)Nkx3.2 fragment containing 1st to 307th amino acidsSEQ ID NO:10Nkx3.2 (42-333)Nkx3.2 fragment containing 42nd to 333rd amino acidsSEQ ID NO:11Nkx3.2 (99-333)Nkx3.2 fragment containing 99th to 333rd amino acidsSEQ ID NO:12Nkx3.2 (112-333)Nkx3.2 fragment containing 112th to 333rd amino acidsSEQ ID NO:13Nkx3.2 (123-333)Nkx3.2 fragment containing 123rd 333rd amino acidsSEQ ID NO:14Nkx3.2 (99-330)Nkx3.2 fragment containing 99th to 330th amino acidsSEQ ID NO:15Nkx3.2 (99-327)Nkx3.2 fragment containing 99th to 327th amino acidsSEQ ID NO:16Nkx3.2 (99-320)Nkx3.2 fragment containing 99th to 320th amino acidsSEQ ID NO:17Nkx3.2 (105-327)Nkx3.2 fragment containing 105th to 327th amino acidsSEQ ID NO:18Nkx3.2 (110-324)Nkx3.2 fragment containing 110th to 324th amino acidsSEQ ID NO:19Nkx3.2 (112-320)Nkx3.2 fragment containing 112th to 320th amino acidsSEQ ID NO:20Nkx3.2 (123-320)Nkx3.2 fragment containing 123rd 320th amino acidsSEQ ID NO:21Nkx3.2 (130-320)Nkx3.2 fragment containing 130th to 320th amino acidsSEQ ID NO:22Nkx3.2 (150-320)Nkx3.2 fragment containing 150th to 320th amino acidsSEQ ID NO:23Nkx3.2 (153-318)Nkx3.2 fragment containing 153rd 318th amino acidsSEQ ID NO:24Nkx3.2 (156-316)Nkx3.2 fragment containing 156th to 316th amino acidsSEQ ID NO:25Nkx3.2 (159-314)Nkx3.2 fragment containing 159th to 314th amino acidsSEQ ID NO:26Nkx3.2 (162-312)Nkx3.2 fragment containing 162nd to 312th amino acidsSEQ ID NO:27Nkx3.2 (165-310)Nkx3.2 fragment containing 165th to 310th amino acidsSEQ ID NO:28 Example 2. Selection of Nkx3.2 fragments resistant to proteolysis mediated by Siah1

[0053] Using the expression vectors expressing the Nkx3.2 fragments as constructed in Example 1, Nkx3.2 fragments which are not degraded by Siah1 were selected by the following method.

[0054] First, Siah1 (SEQ ID NO: 29; GenBank Accession No. AAH35562.1) was amplified by PCR in the same condition and method as described in Example 1, and the amplified PCR product was cleaved with EcoRI and NcoI. The resulting product was inserted into a pCS 3HA expression vector (Addgene plasmid # 17095, a vector with a 3-HA epitope tag inserted between EcoRI and ClaI sites of pCS2P+), which had been cleaved with the same restriction enzymes and includes a tag in which the human influenza hemagglutinin (HA) amino acid sequence (SEQ ID NO: 33; YPYDVPDYA) is repeated three times, to construct an expression vector expressing Siah1.

[0055] Meanwhile, 293T kidney cell line (Cat. # CRL-3216, ATCC, USA) was cultured in a DMEM (Dulbecco's modified Eagle's medium) medium supplemented with 10% (v / v) fetal bovine serum (FBS) at a condition of 37°C and 5% CO 2 . The prepared cells were dispensed on a 60×15 mm cell culture plate so that the number of cells was 5×10 5< . The cells were transiently transfected using 2 µg of the expression vector expressing Nkx3.2, and 4 µg of each of the expression vectors expressing the Nkx3.2 fragments, respectively, together with 2 µg of the expression vector expressing Siah1. The transfection was carried out using VivaMagic (Cat. # VM001, VIVAGEN CO., LTD., Korea) according to the manufacturer's protocol.

[0056] The entire protein was isolated from the transfected cells and quantitated using a Bio-Rad Laboratories protein kit (Cat. # 500-0116, Bio-Rad Laboratories, Inc., USA). Then, western blotting for each of Nkx3.2, Siah1, and β-actin was carried out by a conventional method. Here, an anti-Nkx3.2 antibody (Cat.# Ab83288, Abcam, Great Britain), an anti-HA antibody (Cat. # 11583816001, Roche, Switzerland), an anti-Myc antibody (Cat.# 11667149001, Roche, Switzerland), and an anti-β-actin antibody (Cat. # LF-PA0207, AbFrontier, Korea) were diluted at 1:1,000, 1:5,000, 1:5,000, and 1:5,000, respectively, in a TBST buffer containing 3% (v / v) bovine serum albumin (BSA), and used. As a result, photographs of western blotting bands are illustrated in FIG. 1, which is summarized in Table 2 below. [Table 2]NameSEQ ID NODegradation by Siah1Nkx3.2(1-333)SEQ ID NO:7+++○Nkx3.2(1-320)SEQ ID NO:9+×Nkx3.2(1-307)SEQ ID NO:10-×Nkx3.2(42-333)SEQ ID NO:11+++○Nkx3.2(99-333)SEQ ID NO:12++×Nkx3.2(112-333)SEQ ID NO:13++×Nkx3.2(123-333)SEQ ID NO:14-×Nkx3.2(99-330)SEQ ID NO:15+++○Nkx3.2(99-327)SEQ ID NO:16+++○Nkx3.2(99-320)SEQ ID NO:17+×Nkx3.2(105-327)SEQ ID NO:18++○Nkx3.2(110-324)SEQ ID NO:19+++○Nkx3.2(112-320)SEQ ID NO:20-×Nkx3.2(123-320)SEQ ID NO:21-×Nkx3.2(130-320)SEQ ID NO:22-×Nkx3.2(150-320)SEQ ID NO:23-×Nkx3.2(153-318)SEQ ID NO:24-×Nkx3.2(156-316)SEQ ID NO:25++×Nkx3.2(159-314)SEQ ID NO:26++×Nkx3.2(162-312)SEQ ID NO:27++×Nkx3.2(165-310)SEQ ID NO:28++×

[0057] As illustrated in FIG. 1 and shown in Table 2, unlike the full-length Nkx3.2 (1-333), a degradation of Nkx3.2 protein by Siah1 did not occur in the fragments Nkx3.2 (1-320), Nkx3.2 (1-307), Nkx 3.2 (123-333), Nkx 3.2 (99-320), Nkx 3.2 (112-320), Nkx 3.2 (123-320), Nkx 3.2 (130-320), Nkx3.2 (150-320), and Nkx3.2 (153-318).Example 3. Identifying whether Nkx3.2 fragments bind to IκBα

[0058] Nkx3.2 induces NF-κB activation through binding to IκBα. Thus, immunoprecipitation was used to identify whether the fragments Nkx 3.2 (112-320), Nkx 3.2 (123-320), Nkx 3.2 (130-320), Nkx 3.2 (150-320), and Nkx 3.2 (153-318) bind to IκBα.

[0059] First, IκBα. (SEQ ID NO: 31; GenBank Accession No. CAB65556) was amplified by PCR in the same condition and method as described in Example 1, and the amplified PCR product was cleaved with EcoRI and XbaI. The resulting product was inserted into a pCS 6Myc expression vector (Addgene plasmid # 17095, a vector with 6-Myc epitope tag inserted between EcoRI and ClaI sites of pCS2P+), which had been cleaved with the same restriction enzymes and includes a tag in which the Myc amino acid sequence (SEQ ID NO: 34: EQKLISEEDL) is repeated six times, to construct an expression vector expressing IκBα.

[0060] Then, 293T kidney cell line was transfected in the same condition and method as described in Example 2 using 8 µg of the expression vector expressing Nkx3.2 (1-333) and each of the expression vectors expressing the fragments, respectively, as produced in Example 1, together with an equal amount of the expression vector expressing IκBα. Here, in order to prevent the IκBα protein from being degraded by the Nkx3.2 protein, MG132 (Cat. # 474790, Merck Millipore, Germany), which is a proteasome-degradation suppressor, was added at a concentration of 20 µM. After 6 hours, the entire protein was isolated from the cells, and immunoprecipitation was carried out by a conventional method using an anti-Myc antibody that recognizes the Myc with which IκBα is labeled. Then, western blotting was carried out using the antibodies as described above. Photographs of the obtained results are illustrated in FIG. 2.

[0061] As illustrated in FIG. 2, similar to the full-length Nkx3.2 (1-333), the bands were formed for the fragments Nkx 3.2 (112-320), Nkx 3.2 (123-320), Nkx 3.2 (130-320), Nkx 3.2 (150-320), and Nkx 3.2 (153-318). Therefore, the Nkx3.2 fragments were identified to have the function of binding to IκBα to form a complex, which is necessarily required for activation of NF-κB.Example 4. Identifying whether IκBα protein is degraded by Nkx3.2 fragments

[0062] Nkx3.2 binds to IκBα, and thus promotes ubiquitination and degradation of IκBα by proteasome. Accordingly, western blotting was carried out to identify whether the fragments Nkx3.2 (112-320), Nkx3.2 (123-320), Nkx3.2 (130-320), Nkx3.2 (150-320), and Nkx3.2 (153-318) maintain such activity.

[0063] Meanwhile, ATDC5 cartilage cell line (Cat. # RCB0565, Riken, Japan) was cultured in a DMEM / F12 (Dulbecco's modified Eagle's medium: Nutrient Mixture F-12) medium supplemented with 10% (v / v) fetal bovine serum at a condition of 37°C and 5% CO 2 . The prepared cells were dispensed on a 90×20 mm cell culture plate so that the number of cells was 5×10 5< . The cells were transiently transfected using 4 µg of the expression vector expressing Nkx3.2 (1-333) and 8 µg of each of the expression vectors expressing the Nkx3.2 fragments, respectively, together with 1 µg of the expression vector expressing IκBα. The transfection was carried out using VivaMagic (Cat. # VM001, VIVAGEN CO., LTD., Korea) according to the manufacturer's protocol.

[0064] A subsequent process was such that western blotting was carried out in the same condition and method as described in Example 2, and photographs of the obtained results are illustrated in FIG. 3.

[0065] As shown in FIG. 3, bands with an intensity similar to the full-length Nkx3.2 (1-333) were formed for the fragments Nkx 3.2 (112-320), Nkx 3.2 (123-320), Nkx 3.2 (130-320), Nkx 3.2 (150-320), and Nkx3.2 (153-318). Hence, the Nkx3.2 fragments are identified to induce proteolysis of IκBα at the same level as the full-length Nkx3.2.Example 5. Identifying whether transcriptional function of NF-κB is activated by Nkx3.2 fragments

[0066] Nkx3.2 suppresses cell death of chondrocytes by inducing NF-κB activation. Thus, in order to measure the NF-κB activation by Nkx3.2 fragments, a polynucleotide sequence in which the NF-κB-specific DNA binding site (SEQ ID NO: 35: GGGAATTTCC) is repeated four times was inserted into a pGL3-Basic vector (Cat. # E1751, Promega, USA) using MluI and XhoI to construct a 4x-κB-Luc expression vector. Further, the expression vector was used to measure activation of transcriptional function of NF-κB by Nkx3.2 by analyzing the luciferase activity.

[0067] First, 293T kidney cell line was transiently transfected using, respectively, 200 ng of the expression vector expressing the full-length Nkx3.2 (1-333) and each of the expression vectors expressing the Nkx3.2 fragments, 100 ng of the 4x-κB-Luc expression vector, and 20 ng of a pRL-TK expression vector (Cat. # E2241, Promega, USA).

[0068] Transfection was carried out using VivaMagic according to the manufacturer's protocol. After 24 hours, the luciferase assay was carried out using the Dual-Luciferase Reporter Assay System (Cat. # E1910, Promega, USA) according to the manufacturer's protocol.

[0069] Specifically, a culture of the transfected 293T kidney cell line was removed and washed with 1×PBS. 150 µl of 1× passive lysis buffer (PLB) was added thereto, and the cells were lysed at room temperature for 15 minutes. To 10 µl of the cell lysate, 50 µl of LAR II was added and the resultant was allowed to react. Then, the firefly luciferase activity was measured. To this, 50 µl of Stop & Glo was added and Renilla luciferase activity was measured. In the experimental results, for each sample, the Renilla luciferase activity was normalized to the firefly luciferase activity, and an average of percentages therefor is illustrated in FIG. 4.

[0070] As shown in FIG. 4, when the luciferase activity in the cells transfected with only the pCS2 vector as a negative control is set as 1, not only the full-length Nkx3.2 (1-333) but also the fragments Nkx3.2 (112-320), NKx3.2 (123-320), Nkx3.2 (130-320), Nkx3.2 (150-320), and Nkx3.2 (153-318) exhibited significantly increased luciferase activity. Thus, the Nkx3.2 fragments are identified to possess the function of activating the transcriptional function of NF-κB at the level similar to the full-length Nkx3.2.Example 6: Identification of the improved therapeutic efficacy of Nkx3.2 fragments against degenerative arthritis

[0071] Through the above-described in vitro experiments, functional superiority of the Nkx3.2 fragments as compared with the full-length Nkx3.2 was identified. Accordingly, in order to identify the improved in vivo function of the Nkx3.2 fragments, the therapeutic efficacy of the Nkx3.2 fragment (123-320) and the full-length Nkx3.2 (1-333) against degenerative arthritis was compared and analyzed. For this purpose, a mouse model in which degenerative arthritis was induced through a surgical procedure called destabilization of medial meniscus (DMM) was selected. A process for carrying out the experiment is schematically illustrated in FIG. 6.

[0072] Specifically, the medial meniscus ligament in the knee tissue was cut to induce structural destabilization of the medial meniscus, and thus the femoral cartilage and the tibia cartilage were caused to collide against each other, so that cartilage damage was induced, thereby inducing degenerative arthritis. For a control, an animal group for which the outer skin and the inner skin of the knee were dissected and sutured by a mock surgery was used. The animal group for which degenerative arthritis were induced and the control for which the mock surgery were performed were grown for 8 weeks. Then, an adeno-associated virus (AAV) expressing the Nkx3.2 fragment (123-320) or the full-length Nkx3.2 (1-333), or an empty vector AAV was intra-articularly injected into the corresponding knee, and the animal groups were grown for 4 weeks. A progression degree of degenerative arthritis was analyzed by histopathological analysis.

[0073] For the histopathological analysis, a safranin-O staining method was employed. Safranin-O is a cationic compound stain and effectively adheres to an anionic group of cartilage heparan sulfate proteoglycan so that red color is exhibited. A reddish dark-stained area is evaluated to be cartilage tissue in a healthy condition. Conversely, a part that exhibits weak or no safranin-O staining, and a part with damaged tissue are interpreted as lesions in which the pathology of degenerative arthritis has progressed.

[0074] As shown in FIG. 7, in the case of the control group in which the empty vector AAV is intra-articularly injected, an extremely severe cartilage damage and degeneration phenomenon were observed regardless of the amount of viral particles administered.

[0075] In the case of the comparison group in which AAV expressing the full-length Nkx3.2 (1-333) is intra-articularly injected, significant therapeutic efficacy against degenerative arthritis was observed only in the AAV-administered group at 1×10 10< .

[0076] On the contrary, in the case of the experimental group in which AAV expressing the NKx3.2 fragment (123-320) is intra-articularly injected, a superior therapeutic effect against degenerative arthritis was exhibited from the AAV-administered group at 1.25×10 9< , which is the lowest dose. That is, in the case of the Nkx3.2 fragment (123-320), the therapeutic efficacy against degenerative arthritis is identified to be improved by at least 10 times, compared with the full-length Nkx3.2 (1-333).

[0077] All data obtained through the histopathological analysis were quantitatively evaluated, and the results are graphically illustrated in FIG. 8. The number of animals analyzed in each experimental group was 3, and severity of degenerative arthritis was evaluated on a scale of 0 to 5. From the results, a bar graph was prepared. Mean with SEM was indicated by an error bar. Virus particle doses A, B, C, and D were 1.25×10 9< , 2.5×10 9< , 5×10 9< , and 1×10 10< , respectively, in this increasing order.

[0078] As shown in FIG. 8, in the case of the control in which the empty vector AAV is intra-articularly injected, a high score of 4.5 to 5 was evaluated regardless of the amount of viral particles administered. In addition, in the comparison group in which AAV expressing the full-length Nkx3.2 (1-333) is intra-articularly injected, a low score of 1.5 was evaluated only in the AAV-administered group at 1×10 10< . On the contrary, in the case of the experimental group in which AAV expressing the NKx3.2 fragment (123-320) is intra-articularly injected, an extremely low score of 1 or less was evaluated starting from the AAV-administered group at 1.25×10 9< , which is the lowest dose. Namely, the Nkx3.2 fragment (123-320) is identified to have superior therapeutic efficacy against degenerative arthritis, compared with the full-length Nkx3.2 (1-333).

Claims

1. A polypeptide consisting of the amino acid sequence of SEQ ID NO: 9, 10, 12, 13, 14, 17, 20, 21, 22, 23, 24, 25, 26, 27, or 28.

2. A polynucleotide encoding the polypeptide according to claim 1.

3. An expression vector comprising the polynucleotide according to claim 2 and capable of expressing a polypeptide as defined in claim 1.

4. A host cell comprising the expression vector according to claim 3.

5. A recombinant virus comprising the polynucleotide of claim 2 and capable of expressing a polypeptide as defined in claim 1.

6. The recombinant virus of claim 5, wherein the virus is any one selected from the group consisting of an adenovirus, an adeno-associated virus (AAV), a retrovirus, a lentivirus, a herpes simplex virus, and a vaccinia virus.