Physiologically active protein originating in mammals

Abstract

The present invention provides novel physiologically active protein molecules originating in mammals, which are specifically expressed in arteriosclerosis and/or coronary restenosis, and are predicted to relate closely to the onset and progress of these diseases; DNAS encoding the protein molecules; antibodies reactive with the molecules; and pharmaceutical compositions comprising the above protein molecule or the antibody. The protein molecules, DNAs, and antibodies are useful for treating and preventing arteriosclerosis.

Description

TECHNICAL FIELD

[0001] The present invention relates to a novel physiologically active protein originating in mammals, a DNA encoding said protein, and an antibody reactive with said protein.

BACKGROUND ART

[0002] A so-called geriatric disease, which is regarded as a current disease in high living standard society, includes arteriosclerosis as well as hypertension and diabetes. Important measures for preventing these diseases are not only development of therapeutic methods but also daily life control.

[0003] Arteriosclerosis begins with pathological changes (for example, (1) invasive growth of smooth muscle cells into inner membrane, (2) qualitative and quantitative changes of collagen, elastin, and acidic mucopolysaccharides, and (3) cell foaming by lipid accumulation in the cytoplasm of grown smooth muscle cells and macrophages implanting tissues) occurring in inner membrane of artery. As the result of such pathological changes, (1) foam cells found in the inner membrane produces fat spots on the surface of the inner membrane, (2) lipid accumulates between tissues (deep part of midmembrane) and the inner membrane surface is covered with thick glass-like membrane, accompanied by fibrous growth and calcification, and (3) bleeding and necrosis occur in tissues to cause combined pathological changes involving thrombogenesis, calcification, and deposition of lipid crystals. Such pathological changes, in time, distribute in artery of a whole body and narrow the cavity of the artery. In addition, the site of pathological changes becomes bursal and the vascular wall loses elasticity, thereby hardening blood vessels. The vessels then wind, and normal blood flow is inhibited.

[0004] Epidemiological studies so far have illustrated age (about thirties or more), hypercholesterolemia, hypo-HDL-cholesterolemia, systolic hypertension, obesity, hemoglobin high value, and diabetes as risk factors of the onset of arteriosclerosis. Dynamics of in vivo factors inducing the onset include secretion of adrenalin, increase of thromboxane A2, decrease of prostacyclin, increase of serum peroxylipid, increase of free fatty acid, increase of platelet, increase of fibrinogen, increase of blood coagulation factors (XII and XIII), decrease of tissue plasmin, increase of prostaglandin, decrease of antithrombin III, increase of serum LDL, decrease of serum HDL, increase of insulin, and increase of renin.

[0005] Studies so far have revealed only that multiple conditions, for example, physical conditions such as age and obesity, complication with other diseases, and abnormalities of the dynamics of many in vivo factors complicatedly are related to each other to cause arteriosclerosis.

[0006] Treatments of arteriosclerosis are divided with their purpose into (1) preventive treatments to retract arteriosclerosis and to prevent the onset of arteriosclerosis by correcting lifestyle and physical abnormalities such as obesity (for example, diet therapy and therapeutic exercise) and (2) chemotherapy or surgical therapy to remove vessel occlusion symptoms occurring with the progress of arteriosclerosis or to prevent the onset of vessel cavity occlusion symptoms by thrombus or embolus,.

[0007] Since particular decisive causes of arteriosclerosis are unclear, only symptomatic treatment by chemotherapy is currently possible. For example, &bgr; blocker is applied when the enhancement of a catecholamine derivative such as adrenalin is suspected as the cause, eicosapentaenoic acid is applied for a prostaglandin derivative, vitamin E is applied for peroxylipid, and urokinase is applied for thrombus. No effective pharmaceuticals for treating the arteriosclerosis have been provided yet.

[0008] In the surgical therapy for arterial occulsion, percutaneous transluminal coronary angioplasty (PTCA) based on the observation by angiography prevails clinically as an effective means to enlarge vessel cavity. PTCA has remarkably progressed and prevailed since it was clinically applied by Gruntzig for the first time in 1977, and the number of the operation has rapidly increased in Japan.

[0009] PTCA is the method in which the occlusion (constriction) site is enlarged by inserting a thin catheter with a balloon at the tip in a thick catheter into the coronary artery occlusion site and by expanding the balloon.

[0010] However, in cavity enlargement by PTCA, restenosis occurs at the operation site of the artery in about 30 to 50% of the cases within a few months after the operation, and this restenosis is a major drawback of PTCA.

[0011] The restenosis has been thought to occur by the amplification of neonatal inner membrane proliferation based on the repair reaction of the injury site of the vascular wall, which has been inevitably caused by the enlargement of the occlusion site by PTCA. Although chemotherapy has been tried for preventing this restenosis, almost no effective drugs have been reported so far.

[0012] As mentioned above, at present, a method for the complete treatment and prevention of arteriosclerosis comprising the prevention of the recurrence of arteriosclerosis and the occurrence of restenosis has not established. It is thus desired to clarify the cause of the onset and progress of arteriosclerosis and to develop a method for the effective treatment and prevention thereof, and therapeutic and preventive drugs.

[0013] Coronary artery restenosis occurring after PTCA is regarded as a clinical model of arteriosclerosis from pathological viewpoints such as neonatal inner membrane proliferation or intimal thickening. Therefore, to diagnose the tissue characteristics of the vascular wall at the restenosis site after PTCA and to elucidate the difference between the characteristics and those of normal vascular wall by comparing them pathologically and at the gene level are effective to identify the cause and factors of restenosis, and further, arteriosclerosis.

[0014] In such comparative studies, a useful method for comparison and examination at the gene level using the genetic engineering technique is called differential display method (Nucleic Acids Research, Vol.21, No.18, pp.4272-4280 (1993); and Science, Vol.257, pp.967-971 (1992)).

[0015] Specifically, PCTA is applied to the coronary artery of a large mammal such as a rabbit, the expression patterns of genes in the inner membrane tissue at the PTCA site are examined by differential display method, and they are compared with the gene expression patterns in the inner membrane tissue without PCTA, to thereby identify genes specifically or increasingly expressed after PTCA.

DISCLOSURE OF THE INVENTION

[0016] Genes that express specifically or increasingly after PTCA and proteins derived from said genes may be closely related to arteriosclerosis and restenosis. The present invention provides pharmaceuticals and methods for preventing and treating arteriosclerosis and restenosis by identifying genes and proteins expressing specifically in arteriosclerosis and coronary artery restenosis.

[0017] As the result of studies on the analyses of genes specific to arteriosclerosis and/or coronary artery restenosis, the present inventors have discovered genes encoding two novel proteins (clone BA0306 and BA2303) that express increasingly at the comparatively early stage (day 1 to 7) after PTCA and completed the present invention.

[0018] The two novel protein-encoding genes of the present invention, whose characteristics are mentioned below, are expressed specifically after PTCA, and are thought to be genes involved in onset and progress of arteriosclerosis and/or coronary artery restenosis.

[0019] Clone BA0306 has the following characteristics.

[0020] (1) Its increased expression is observed on day 1 to 7 after PTCA of coronary artery (the peak is observed on day 4).

[0021] (2) Northern blotting reveals the expression of the mRNA as about 3.5 k and about 4.4 k bands in various human tissues.

[0022] (3) It has ten putative transmembrane regions.

[0023] (4) It has amino acid sequence homology with S. cerevisiae oxidative stress resistance protein, S. cerevisiae zinc/cadmium resistance protein, heavy metal ion resistance protein, and so on.

[0024] (5) The molecules derived from humans and rabbits have the amino acid sequences of SEQ ID NO: 10 and 8, respectively. The molecule derived from mice has the amino acid sequence of SEQ ID NO: 28.

[0025] Judging from these characteristics, clone BA0306 is thought to inhibit active oxygen such as nitrogen monoxide (NO), which is involved in the progress of arteriosclerosis and/or restenosis.

[0026] Clone BA2303 has the following characteristics.

[0027] (1) Its increased expression is observed from day 1 after PTCA of coronary artery, and the expression continues until day 7 with the maximum expression on day 2 to 4.

[0028] (2) Northern blotting reveals the expression of the mRNA as about 3.9 k and about 2.1 k bands in various human tissues.

[0029] (3) It has seven putative transmembrane regions.

[0030] (4) The molecules derived from humans and mice have the amino acid sequences of SEQ ID NO: 4 and 6, respectively. The molecule derived from rabbits has the amino acid sequence of SEQ ID NO: 2.

[0031] Judging from these characteristics, clone BA2303 is thought to be a GTP binding protein (G protein)-coupled receptor that transmits a specific signal through intracellular G protein to an effector on the plasma membrane or the surface of the cytoplasm by binding to an in vivo ligand involved in the onset or progress of arteriosclerosis and/or restenosis.

[0032] Therefore, the genes (DNAs), proteins, or their fragments of the present invention and antibodies or a portion of them reactive with the proteins of the present invention are extremely useful for developing drugs for treatment and prevention of arteriosclerosis and for treatment and prevention of restenosis after PTCA for artery occlusion symptom and so on, targeting said genes or protein molecules. In addition, the DNAs of the present invention themselves are useful as antisense pharmaceuticals, extracellular region fragments of said proteins, for example, as soluble receptor pharmaceuticals, and said antibodies and a portion of them as antibody pharmaceuticals.

[0033] Genes (DNAs), proteins, and antibodies of the present invention are useful as reagents for searching proteins (ligands) interacting with the proteins of the present invention, thereby elucidating the function of said ligands, and developing therapeutic drugs targeting said ligands.

[0034] Based on the genetic information of the rabbit- or mouse-derived DNA, one embodiment of DNAs of the present invention, model animals (knockout animals) can be produced by disrupting (inactivating) the endogenous gene corresponding to the DNA. Similarly, transgenic animals can be produced as model animals by introducing the human-derived DNA, one embodiment of DNAs of the present invention, into nonhuman mammals such as mice. Function of genes and proteins of the present invention can be elucidated by analyzing the physical, biological, pathologic, and genetic characteristics of these model animals.

[0035] Moreover, by mating the model animals whose endogenous gene is thus disrupted with the transgenic animals, model animals that have only the human-derived gene of the present invention can be produced. By administering drugs (compounds, antibodies, and so on) targeting the introduced human gene to these model animals, the therapeutic effect of the drug can be estimated.

[0036] Namely, the present invention provides the DNAS, proteins, expression vectors, transformants, antibodies, pharmaceutical compositions, transgenic mice, and knockout, mentioned below.

[0037] (1) A DNA encoding a protein having the amino acid sequence of SEQ ID NO: 4.

[0038] (2) A DNA encoding a protein fragment comprising the extracellular region of a protein having the amino acid sequence of SEQ ID NO: 4.

[0039] (3) A DNA comprising a nucleotide sequence corresponding to nucleotide residues 97 to 1419 of the nucleotide sequence of SEQ ID NO: 3.

[0040] (4) A DNA hybridizing with a DNA having the nucleotide sequence of SEQ ID NO: 3 under stringent conditions.

[0041] (5) A protein having the amino acid sequence of SEQ ID NO: 4 or an amino acid sequence substantially the same as said amino acid sequence.

[0042] (6) A protein fragment comprising the extracellular region of a protein having the amino acid sequence of SEQ ID NO: 4 or an amino acid sequence substantially the same as said amino acid sequence.

[0043] (7) A fusion protein between the extracellular region of the protein of (5) and the constant region of the heavy chain of human immunoglobulin (Ig) or a portion of the constant region. (8) An expression vector comprising the DNA of any one of (1) to (4).

[0044] (9) A transformant carrying the expression vector of (8).

[0045] (10) An antibody or its portion reactive with the protein of (5) or the protein fragment of (6).

[0046] (11) The antibody or its portion of (10), wherein the antibody is a monoclonal antibody.

[0047] (12) A pharmaceutical composition comprising the protein fragment of (6) or the fusion protein of (7) and a pharmaceutically acceptable carrier.

[0048] (13) A pharmaceutical composition comprising the antibody or its portion of (10) or (11) and a pharmaceutically acceptable carrier.

[0049] (14) A DNA encoding a protein having the amino acid sequence of SEQ ID NO: 10.

[0050] (15) A DNA encoding a protein fragment comprising the extracellular region of a protein having the amino acid sequence of SEQ ID NO: 10.

[0051] (16) A DNA having a nucleotide sequence corresponding to nucleotide residues 1 to 1785 of the nucleotide sequence of SEQ ID NO: 9.

[0052] (17) A DNA hybridizing with a DNA having the nucleotide sequence of SEQ ID NO: 9 under stringent conditions.

[0053] (18) A protein having the amino acid sequence of SEQ ID NO: 10 or an amino acid sequence substantially the same as said amino acid sequence.

[0054] (19) A protein fragment comprising the extracellular region of a protein having the amino acid sequence of SEQ ID NO: 10 or an amino acid sequence substantially the same as said amino acid sequence.

[0055] (20) A fusion protein comprising the extracellular region of the protein of (18) and the constant region of the heavy chain of human immunoglobulin (Ig) or a portion of the constant region.

[0056] (21) An expression vector comprising the DNA of any one of (14) to (17).

[0057] (22) A transformant carrying the expression vector of (21).

[0058] (23) An antibody or its portion reactive with the protein of (18) or the protein fragment of (19).

[0059] (24) The antibody or its portion of (23), wherein the antibody is a monoclonal antibody.

[0060] (25) A pharmaceutical composition comprising the protein fragment of (19) or the fusion protein of (20) and a pharmaceutically acceptable carrier.

[0061] (26) A pharmaceutical composition comprising the antibody or its portion of (23) or (24) and a pharmaceutically acceptable carrier.

[0062] (27) A transgenic mouse in which the human-derived DNA comprising a DNA having a nucleotide sequence corresponding to nucleotide residues 97 to 1419 of the nucleotide sequence of SEQ ID NO: 3 is integrated into an endogenous gene of said mouse.

[0063] (28) A transgenic mouse in which the human-derived DNA comprising a DNA having a nucleotide sequence corresponding to nucleotide residues 1 to 1785 of the nucleotide sequence of SEQ ID NO: 9 is integrated into an endogenous gene of said mouse.

[0064] (29) A knockout mouse whose endogenous gene encoding a mouse-derived protein having the amino acid sequence of SEQ ID NO: 6 is inactivated so that said protein is not produced.

[0065] (30) A knockout mouse whose endogenous gene encoding a mouse-derived protein comprising the amino acid sequence of SEQ ID NO: 28 is inactivated so that said protein is not produced.

[0066] In the following, the present invention is explained in detail by clarifying the meanings of terms used in the present application and the general production methods of proteins, protein fragments, fusion proteins, DNAs, antibodies, transgenic mice, and knockout mice of the present invention.

[0067] A “protein” of the present invention means a protein and its fragment derived from mammals such as humans, rabbits, and mice, and preferably, a human-derived protein and its fragment.

[0068] Particularly preferable examples are (1) a protein having the amino acid sequence of SEQ ID NO: 4 or an amino acid sequence substantially the same as said amino acid sequence, (2) a protein fragment comprising the extracellular region of a protein having the amino acid sequence of SEQ ID NO: 4 or an amino acid sequence substantially the same as said amino acid sequence, (3) a protein having the amino acid -sequence of SEQ ID NO: 10 or an amino acid sequence substantially the same as said amino acid sequence, and (4) a protein fragment comprising the extracellular region of a protein having the amino acid sequence of SEQ ID NO: 10 or an amino acid sequence substantially the same as said amino acid sequence.

[0069] The term “extracellular region” used herein is explained below. A transmembrane protein such as a G protein-coupled receptors or cell surface molecule connects with the membrane through the hydrophobic peptide region penetrating the lipid bilayer of the membrane once or several times and has structure composed of three main regions, that is, extracellular region, transmembrane region, and cytoplasmic region. Such a transmembrane protein exists as a monomer, homodimer, heterodimer, or oligomer with another chain(s) having the same or different amino acid sequence.

[0070] The term “extracellular region” used herein means the partial structure (partial sequence) existing outside of the membrane that holds the transmembrane protein as mentioned above among the whole structure of said membrane protein. In other words, it corresponds to the region excluding the region incorporated into the membrane (transmembrane region) and the region existing in the cytoplasm following the transmembrane region (cytoplasmic region). If desired, one to five amino acids derived from the amino acids constituting the transmembrane and/or cytoplasmic region can be added to the N-terminus and/or C-terminus of the extracellular region in the present invention.

[0071] Here, “having substantially the same amino acid sequence” means to include a protein having an amino acid sequence where multiple amino acids, preferably 1 to 10 amino acids, particularly preferably 1 to 5 amino acids, in the amino acid sequence shown in SEQ ID NO: 4 or 10, are substituted, deleted, and/or modified, and a protein having an amino acid sequence where multiple amino acids, preferably 1 to 10 amino acids, particularly preferably 1 to 5 amino acids, are added to said amino acid sequence, as far as the protein has substantially the same biological properties as the protein having said amino acid sequence.

[0072] Alphabetical triplet or single letter codes used to represent amino acids in the present specification or figures mean amino acids as follows. (Gly/G) glycine, (Ala/A) alanine, (Val/V) valine, (Leu/L) leucine, (Ile/I) isoleucine, (Ser/S) serine, (Thr/T) threonine, (Asp/D) aspartic acid, (Glu/E) glutamic acid, (Asn/N) asparagine, (Gln/Q) glutamine, (Lys/K) lysine, (Arg/R) arginine, (Cys/C) cysteine, (Met/M) methionine, (Phe/F) phenylalanine, (Tyr/Y) tyrosine, (Trp/W) tryptophane, (His/H) histidine, (Pro/P) proline.

[0073] “The constant region or a portion of the constant region of human immunoglobulin (Ig) heavy chain” used herein means the constant region or the Fc region of human-derived immunoglobulin heavy chain (H chain) as described, or a portion of them. The immunoglobulin can be any immunoglobulin belonging to any class and any subclass. Specifically, examples of the immunoglobulin are IgG (IgG1, IgG2, IgG3, and IgG4), IgM, IgA (IgA1 and IgA2), IgD, and IgE. Preferably, the immunoglobulin is IgG (IgG1, IgG2, IgG3, or IgG4), or IgM. Examples of particularly preferable immunoglobulin of the present invention are those belonging to human-derived IgG (IgG1, IgG2, IgG3, or IgG4).

[0074] Immunoglobulin has a Y-shaped structural unit in which four chains composed of two homologous light chains (L chains) and two homologous heavy chains (H chains) are connected through disulfide bonds (S—S bonds). The light chain is composed of the light chain variable region (VL) and the light chain constant region (CL). The heavy chain is composed of the heavy chain variable region (VH) and the heavy chain constant region (CH).

[0075] The heavy chain constant region is composed of some domains having the amino acid sequences inherent in each class (IgG, IgM, IgA, IgD, and IgE) and each subclass (IgG1, IgG2, IgG3, and IgG4, IgA1, and IgA2).

[0076] The heavy chain of IgG (IgG1, IgG2, IgG3, and IgG4) is composed of VH, CH1 domain, hinge region, CH2 domain, and CH3 domain in this order from N terminus.

[0077] Similarly, the heavy chain of IgG1 is composed of VH, C&ggr;11 domain, hinge region, C&ggr;12 domain, and C&ggr;13 domain in this order from N terminus. The heavy chain of IgG2 is composed of VH, C&ggr;21 domain, hinge region, C&ggr;22 domain, and C&ggr;23 domain in this order from N terminus. The heavy chain of IgG3 is composed of VH, C&ggr;31 domain, hinge region, C&ggr;32 domain, and C&ggr;33 domain in this order from N terminus. The heavy chain of IgG4 is composed of VH, C&ggr;41 domain, hinge region, C&ggr;42 domain, and C&ggr;43 domain in this order from N terminus.

[0078] The heavy chain of IgA is composed of VH, C&agr;1 domain, hinge region, C&agr;2 domain, and C&agr;3 domain in this order from N terminus.

[0079] Similarly, the heavy chain of IgA1 is composed of VH, C&agr;11 domain, hinge region, C&agr;12 domain, and C&agr;13 domain in this order from N terminus. The heavy chain of IgA2 is composed of VH, C&agr;21 domain, hinge region, C&agr;22 domain, and C&agr;23 domain in this order from N terminus.

[0080] The heavy chain of IgD is composed of VH, C&dgr;1 domain, hinge region, C&dgr;2 domain, and C&dgr;3 domain in this order from N terminus.

[0081] The heavy chain of IgM is composed of VH, C&mgr;1 domain, C&mgr;2 domain, C&mgr;3 domain, and C&mgr;4 domain in this order from N terminus and have no hinge region as seen in IgG, IgA, and IgD.

[0082] The heavy chain of IgE is composed of VH, C&egr;1 domain, C&egr;2 domain, C&egr;3 domain, and C&egr;4 domain in this order from N terminus and have no hinge region as seen in IgG, IgA, and IgD.

[0083] If, for example, IgG is treated with papain, it is cleaved at the slightly N terminal side beyond the disulfide bonds existing in the hinge region where the disulfide bonds connect the two heavy chains to generate two homologous Fab, in which a heavy chain fragment composed of VH and CH1 is connected with one light chain through a disulfide bond, and one Fc, in which two homologous heavy chain fragments composed of the hinge region, CH2 domain, and CH3 domain are connected through disulfide bonds (See “Immunology Illustrated”, original 2nd ed., Nankodo, pp.65-75 (1992); and “Focus of Newest Medical Science ‘Recognition Mechanism of Immune System’”, Nankodo, pp.4-7 (1991); and so on).

[0084] Namely, “a portion of a constant region of immunoglobulin heavy chain” of the present invention means a portion of a constant region of an immunoglobulin heavy chain having the structural characteristics as mentioned above, and preferably, is the constant region without C1 domain, or the Fc region. Specifically, examples thereof are the region composed of hinge region, C2 domain, and C3 domain from each of IgG, IgA, and IgD, and are the region composed of C2 domain, C3 domain, and C4 domain from each of IgM and IgE. A particularly preferable example thereof is the Fc region of human-derived IgG1.

[0085] The “fusion protein” of the present invention is that composed of the above-described extracellular region of the protein of the present invention and a constant region or a portion of a constant region of human immunoglobulin (Ig) heavy chain. Preferably, it is a fusion polypeptide composed of an extracellular region of a protein of the present invention and a portion of a constant region of human IgG heavy chain, and particularly preferably, it is a fusion polypeptide composed of an extracellular region of a protein of the present invention and the region (Fc) composed of a hinge region, CH2 domain, and CH3 domain of human IgG heavy chain. Moreover, IgG1 is preferable among IgG. In addition, a protein derived from human, mouse, or rat (preferably, human) is preferable as the protein of the present invention.

[0086] The fusion protein of the present invention has the advantage that the fusion polypeptide can be purified extremely easily by using affinity column chromatography using the property of protein A, which binds specifically to the immunoglobulin fragment because the fusion polypeptide of the present invention has a portion of a constant region (for example Fc) of an immunoglobulin such as IgG as mentioned above as a fusion partner. Moreover, since various antibodies against the Fc of various immunoglobulin are available, an immunoassay for the fusion polypeptides can be easily performed with antibodies against the Fc.

[0087] The protein, protein fragment, and fusion protein of the present invention can be produced not only by recombinant DNA technology as mentioned below but also by a method well known in the art such as a chemical synthetic method and a cell culture method, or a modified method thereof.

[0088] The DNA of the present invention encodes the above-mentioned protein of the present invention, and includes any nucleotide sequence that can encode the protein of the present invention. The DNA preferably encodes a human-derived protein of the present invention. Specific examples of the DNA are described below.

[0089] (1) A DNA encoding a protein having the amino acid sequence of SEQ ID NO: 4, a protein fragment composed of the extracellular region of said protein, or a biological analog obtained by substituting, deleting, and/or modifying multiple amino acids, preferably 1 to 10 amino acids, particularly preferably 1 to 5 amino acids in the amino acid sequence of said protein or fragment, or by inserting multiple amino acids, preferably 1 to 10 amino acids, particularly preferably 1 to 5 amino acids, in said amino acid sequence.

[0090] (2) A DNA encoding a protein having the amino acid sequence of SEQ ID NO: 10, a protein fragment composed of the extracellular region of said protein, or a biological analog obtained by substituting, deleting, and/or modifying multiple amino acids, preferably 1 to 10 amino acids, particularly preferably 1 to 5 amino acids, in the amino acid sequence of said protein or fragment, or by inserting multiple amino acids, preferably 1 to 10 amino acids, particularly preferably 1 to 5 amino acids, in said amino acid sequence.

[0091] (3) A DNA hybridizing with a DNA having the nucleotide sequence of SEQ ID NO: 3 under stringent conditions.

[0092] (4) A DNA hybridizing with a DNA having the nucleotide sequence of SEQ ID NO: 9 under stringent conditions.

[0093] Specific examples thereof are (1) a DNA having a nucleotide sequence corresponding to nucleotide residues 97 to 1419 of the nucleotide sequence of SEQ ID NO: 3, (2) a DNA comprising a nucleotide sequence corresponding to nucleotide residues 1 to 1419 of the nucleotide sequence of SEQ ID NO: 3, (3) a DNA having a nucleotide sequence corresponding to nucleotide residues 1 to 1785 of the nucleotide sequence of SEQ ID NO: 9, and (4) a DNA comprising a nucleotide sequence corresponding to nucleotide residues 1 to 1785 of the nucleotide sequence of SEQ ID NO: 9.

[0094] The DNA of the present invention comprises either a genomic DNA or cDNA. In addition, the DNA includes any DNA composed of any codons encoding the same amino acids.

[0095] Examples of “stringent conditions” are as follows. When a probe with 50 or more nucleotides is used and hybridization is performed in 0.9% NaCl, the standard of temperature where 50% dissociation occurs (Tm) is calculated using the following formula and the temperature for hybridization can be determined according to the following formula.

Tm=82.3° C.+0.41×(G+C)%−500/n−0.61×(formamide)%

[0096] (n means the number of the nucleotide of probe).

[0097] Temperature=Tm−25° C.

[0098] In addition, when a probe with 100 or more nucleotides (G+C=40 to 50%) is used, it should be considered that Tm varies as (1) and (2) mentioned below.

[0099] (1) Tm descends by about 1° C. per 1% mismatch.

[0100] (2) Tm descends by 0.6 to 0.7° C. per 1% formamide.

[0101] Accordingly, the temperature conditions for the combination of completely complementary strands can be set as follows.

[0102] (A) 65 to 75° C. (formamide not added)

[0103] (B) 35 to 45° C. (in the presence of 50% formamide)

[0104] The temperature conditions for the combination of incompletely complementary strands can be set as follows.

[0105] (A) 45 to 55° C. (formamide not added)

[0106] (B) 35 to 42° C. (in the presence of 30% formamide)

[0107] The temperature conditions when a probe with 23 or less nucleotides is used can be 37° C. or can be calculated using the following formula. Temperature=2° C.×(the number of A+T)+4° C.×(the number of C+G) −5° C.

[0108] The DNA of the present invention can be a DNA obtained by any method. For example, the DNA includes complementary DNA (cDNA) prepared from mRNA, DNA prepared from genomic DNA, DNA prepared by chemical synthesis, DNA obtained by PCR amplification with RNA or DNA as a template, and DNA constructed by appropriately combining these methods.

[0109] The DNA encoding the protein of the present invention can be obtained by the usual method such as a method to clone cDNA from mRNA encoding the protein of the present invention, a method to isolate genomic DNA and then splice them, chemical synthesis and so on.

[0110] (1) cDNA can be cloned from the mRNA encoding the protein of the present invention by, for example, the method described below.

[0111] First, the mRNA encoding the protein of the present invention is prepared from the above-described tissues or cells expressing and producing a cell surface molecule (polypeptide) of the present invention. mRNA can be prepared isolating total RNA by a known method such as quanidine-thiocyanate method (Chirgwin et al., Biochemistry, Vol.18, p5294, 1979), hot phenol method, or AGPC method, and subjecting it to affinity chromatography using oligo-dT cellulose or poly-U Sepharose.

[0112] Then, with the mRNA obtained as a template, cDNA is synthesized, for example, by a well-known method using reverse transcriptase such as the method of Okayama et al. (Mol. Cell. Biol. Vol.2, p.161 (1982); ibid. Vol.3, p.280 (1983)) or the method of Hoffman et al. (Gene Vol.25, p.263 (1983)), and converted into double-stranded cDNA. A cDNA library is prepared by transforming E. coli with plasmid vectors, phage vectors, or cosmid vectors having this cDNA or by transfecting E. coli after in vitro packaging.

[0113] The plasmid vectors used in this invention are not limited as long as they are replicated and maintained in hosts. Any phage vectors that can be replicated in hosts can also be used. Examples of usually used cloning vectors are pUC19, &lgr;gt10, &lgr;gt11, and so on. When the vector is applied to immunological screening as mentioned below, the vector having a promoter that can express a gene encoding the polypeptide of the present invention in a host is preferably used.

[0114] cDNA can be inserted into a plasmid by, for example, the method of Maniatis et al. (Molecular Cloning, A Laboratory Manual, second edition, Cold Spring Harbor Laboratory, p.1.53, 1989). cDNA can be inserted into a phage vector by, for example, the method of Hyunh et al. (DNA cloning, a practical approach, Vol.1, p.49 (1985)). These methods can be simply performed by using a commercially available cloning kit (for example, a product from Takara Shuzo). The recombinant plasmid or phage vector thus obtained is introduced into appropriate host cells such as a prokaryote (for example, E. coli: HB101, DH5 &agr;, MC1061/P3, etc.).

[0115] Examples of a method for introducing a plasmid into a host are calcium chloride method, calcium chloride/rubidium chloride method described in Molecular Cloning, A Laboratory Manual (second edition, Cold Spring Harbor Laboratory, p.1.74 (1989)), and electroporation method. Phage vectors can be introduced into host cells by, for example, a method in which the phage DNAs are introduced into grown hosts after in vitro packaging. In vitro packaging can be easily performed with a commercially available in vitro packaging kit (for example, a product from Stratagene or Amersham).

[0116] The cDNA encoding the protein of the present invention can be isolated from the cDNA library so prepared according to the method mentioned above by combining general cDNA screening methods.

[0117] For example, a clone comprising the desired cDNA can be screened by a known colony hybridization method (Crunstein et al. Proc. Natl. Acad. Sci. USA, Vol.72, p.3961 (1975)) or plaque hybridization method (Molecular Cloning, A Laboratory Manual, second edition, Cold Spring Harbor Laboratory, p.2.108 (1989)) using 32P-labeled chemically synthesized oligonucleotides as probes, which are corresponding to the amino acid sequence of the polypeptide of the present invention. Alternatively, a clone having a DNA fragment encoding a specific region within the polypeptide of the present invention can be screened by amplifying the region by PCR with synthetic PCR primers.

[0118] When a cDNA library prepared using a cDNA expression vector (for example, &lgr;ZAPII phage vector) is used, the desired clone can be screened by the antigen-antibody reaction using an antibody against the polypeptide of the present invention. A screening method using PCR method is preferably used when many clones are subjected to screening.

[0119] The nucleotide sequence of the DNA thus obtained can be determined by Maxam-Gilbert method (Maxam et al. Proc. Natl. Acad. Sci. USA, Vol.74, p.560 (1977)) or the dideoxynucleotide synthetic chain termination method using phage M13 (Sanger et al. Proc. Natl. Acad. Sci. USA, Vol.74, pp.5463-5467 (1977)). The whole or a portion of the gene encoding the polypeptide of the present invention can be obtained by excising the clone obtained as mentioned above with restriction enzymes and so on.

[0120] (2) The DNA encoding the polypeptide of the present invention can be isolated from the genomic DNA derived from the cells expressing the polypeptide of the present invention as mentioned above by the following methods. Such cells are solubilized preferably by SDS or proteinase K, and the DNAs are deproteinized by repeating phenol extraction. RNAs are digested preferably with ribonuclease. The DNAs obtained are partially digested with appropriate restriction enzymes, and the DNA fragments obtained are amplified with appropriate phage or cosmid to generate a library. Then, clones having the desired sequence are detected, for example, by using radioactively labeled DNA probes, and the whole or a portion of the gene encoding the protein of the present invention is obtained from the clones by excision with restriction enzyme and so on.

[0121] (3) The DNA of the present invention can also be chemically synthesized by the usual method, based on the nucleotide sequence of SEQ ID NO: 1, 3, 5, 7, 9, or 27.

[0122] The present invention also relates to a recombinant vector comprising the DNA encoding the protein of the present invention. The recombinant vector of the present invention is not limited as long as it can be replicated and maintained or can autonomously replicate in various prokaryotic and/or eukaryotic hosts. The vector of the present invention includes plasmid vectors and phage vectors.

[0123] The recombinant vector can easily be prepared by ligating the DNA encoding the protein of the present invention with a vector for recombination available in the art (plasmid DNA and bacteriophage DNA) by the usual method. Specific examples of the vectors for recombination used are E. coli-derived plasmids such as pBR322, pBR325, pUC12, pUC13, and pUC19, yeast-derived plasmids such as pSH19 and pSH15, and Bacillus subtilis-derived plasmids such as pUB110, pTP5, and pC194. Examples of phages are a bacteriophage such as &lgr; phage, and an animal or insect virus (pVL1393, Invitrogen) such as a retrovirus, vaccinia virus, and nuclear polyhedrosis virus.

[0124] An expression vector is useful for expressing the DNA encoding the protein of the present invention and for producing the polypeptide of the present invention. The expression vector is not limited as long as it expresses the gene encoding the polypeptide of the present invention in various prokaryotic and/or eukaryotic host cells and produces this protein. Examples thereof are PMAL C2, pEF-BOS (Nucleic Acids Res. Vol.18, p.5322 (1990)), pME18S (Experimental Medicine: SUPPLEMENT, “Handbook of Genetic Engineering” (1992)), and so on.

[0125] When bacteria, particularly E. coli are used as host cells, an expression vector is generally comprised of, at least, a promoter/operator region, an initiation codon, the DNA encoding the protein of the present invention, termination codon, terminator region, and replicon.

[0126] When yeast, animal cells, or insect cells are used as hosts, an expression vector is preferably comprised of, at least, a promoter, an initiation codon, the DNA encoding the protein of the present invention, and a termination codon. It may also comprise the DNA encoding a signal peptide, enhancer sequence, 5′- and 3 ′-untranslated region of the gene encoding the protein of the present invention, splicing junctions, polyadenylation site, selectable marker region, and replicon. The expression vector may also contain, if required, a gene for gene amplification (marker) that is usually used.

[0127] A promoter/operator region to express the polypeptide of the present invention in bacteria comprises a promoter, an operator, and a Shine-Dalgarno (SD) sequence (for example, AAGG). For example, when the host is Escherichia, it preferably comprises Trp promoter, lac promoter, recA promoter, &lgr; PL promoter, lpp promoter, tac promoter, or the like. Examples of a promoter to express the polypeptide of the present invention in yeast are PH05 promoter, PGK promoter, GAP promoter, ADH promoter, and so on. When the host is Bacillus, examples thereof are SL01 promoter, SP02 promoter, penP promoter and so on. When the host is a eukaryotic cell such as a mammalian cell, examples thereof are SV40-derived promoter, retrovirus promoter, heat shock promoter, and so on, and preferably Sv-40 and retrovirus-derived one. As a matter of course, the promoter is not limited to the above examples. In addition, to use an enhancer is effective for expression.

[0128] A preferable initiation codon is, for example, a methionine codon (ATG).

[0129] The commonly used termination codon (for example, TAG, TGA, TAA, and so on) is illustrated as a termination codon.

[0130] Usually used natural or synthetic terminators are used as a terminator region.

[0131] A replicon means a DNA capable of replicating the whole DNA sequence in host cells, and includes a natural plasmid, an artificially modified plasmid (DNA fragment prepared from a natural plasmid), a synthetic plasmid, and so on. Examples of a preferable plasmids are pBR322 or its artificial derivatives (DNA fragment obtained by treating pBR322 with appropriate restriction enzymes) for E. coli, yeast2 &mgr; plasmid or yeast chromosomal DNA for yeast, and pRSVneo ATCC 37198, pSV2dhfr ATCC 37145, pdBPV-MMTneo ATCC 37224, pSV2neo ATCC 37149, etc. for mammalian cells.

[0132] An enhancer sequence, polyadenylation site, and splicing junction that are usually used in the art, such as those derived from SV40 can be also used.

[0133] A selectable marker usually used can be used according to the usual method. Examples thereof are resistance genes for antibiotics, such as tetracycline, neomycin, ampicillin, or kanamycin, and thymidine kinase gene.

[0134] Examples of a gene for gene amplification are dihydrofolate reductase (DHFR) gene, thymidine kinase gene, neomycin resistance gene, glutamate synthase gene, adenosine deaminase gene, ornithine decarboxylase gene, hygromycin-B-phophotransferase gene, aspartate transcarbamylase gene, etc.

[0135] The expression vector of the present invention can be prepared by continuously and circularly linking at least the above-mentioned promoter, initiation codon, DNA (gene) encoding the polypeptide of the present invention, termination codon, and terminator region, to an appropriate replicon. If desired, appropriate DNA fragments (for example, linkers, restriction sites generated with other restriction enzyme), can be used by the usual method such as digestion with a restriction enzyme or ligation using T4 DNA ligase.

[0136] Transformants of the present invention can be prepared by introducing the expression vector mentioned above into host cells.

[0137] Host cells used in the present invention are not limited as long as they are compatible with an expression vector mentioned above and can be transformed. Examples thereof are various cells such as natural cells or artificially established recombinant cells usually used in technical field of the present invention (for example, bacteria (Escherichia and Bacillus), yeast (Saccharomyces, Pichia, etc.), animal cells, or insect cells.

[0138] E. coli or animal cells are preferably used. Specific examples are E. coli (DH5&agr;, TB1, HB101, etc.), mouse-derived cells (COP, L, C127, Sp2/0, NS-1, NIH 3T3, etc.), rat-derived cells, hamster-derived cells (BHK, CHO, etc.), monkey-derived cells (COS1, COS3, COS7, CV1, Velo, etc.), and human-derived cells (Hela, diploid fibroblast-derived cells, HEK293, myeloma, Namalwa, etc.).

[0139] An expression vector can be introduced (transformed (transduced)) into host cells by known method.

[0140] Transformation can be performed, for example, according to the method of Cohen et al. (Proc. Natl. Acad. Sci. USA, Vol.69, p.2110 (1972)), protoplast method (Mol. Gen. Genet., Vol.168, p.111 (1979)), or competent method (J. Mol. Biol., Vol.56, p.209 (1971)) when the hosts are bacteria (E. coli, Bacillus subtilis, etc.), the method of Hinnen et al. (Proc. Natl. Acad. Sci. USA, Vol.75, p.1927 (1978)), or lithium method (J. Bacteriol., Vol.153, p.163 (1983)) when the host is Saccharomyces cerevisiae, the method of Graham (Virology, Vol.52, p.456 (1973)) when the hosts are animal cells, and the method of Summers et al. (Mol. Cell. Biol., Vol.3, pp.2156-2165 (1983)) when the hosts are insect cells.

[0141] The protein of the present invention can be produced by cultivating transformants (in the following this term includes transductants) comprising an expression vector prepared as mentioned above in nutrient media.

[0142] The nutrient media preferably comprise carbon source, inorganic nitrogen source, or organic nitrogen source necessary for the growth of host cells (transformants). Examples of the carbon source are glucose, dextran, soluble starch, and sucrose, and examples of the inorganic or organic nitrogen source are ammonium salts, nitrates, amino acids, corn steep liquor, peptone, casein, meet extract, soy bean cake, and potato extract. If desired, they may comprise other nutrients (for example, an inorganic salt (for example, calcium chloride, sodium dihydrogenphosphate, and magnesium chloride), vitamins, antibiotics (for example, tetracycline, neomycin, ampicillin, kanamycin, etc.).

[0143] Cultivation is performed by a method known in the art. Cultivation conditions such as temperature, pH of the media, and cultivation time are selected appropriately so that the protein of the present invention is overproduced.

[0144] Specific media and cultivation conditions used depending on host cells are illustrated below, but are not limited thereto.

[0145] When the hosts are bacteria, actinomycetes, yeasts, filamentous fungi, liquid media comprising the nutrient source mentioned above are appropriate. The media with pH 5 to 8 are preferably used.

[0146] When the host is E. coli, examples of preferable media are LB media, and M9 media (Miller et al. Exp. Mol. Genet., Cold Spring Harbor Laboratory, p.431 (1972)). Using these media, cultivation can be performed usually at 14 to 43° C. for about 3 to 24 hours with aeration and stirring, if necessary.

[0147] When the host is Bacillus, cultivation can be performed usually at 30 to 40° C. for about 16 to 96 hours with aeration and stirring, if necessary.

[0148] When the host is yeast, examples of media are Burkholder minimal media (Bostian, Proc. Natl. Acad. Sci. USA, Vol.77, p.4505 (1980)). The pH of the media is preferably 5 to 8. Cultivation can be performed usually at 20 to 35° C. for about 14to 144 hours with aeration and stirring, if necessary.

[0149] When the host is an animal cell, examples of media are MEM media containing about 5 to 20% fetal bovine serum (Science, Vol.122, p.501 (1952)), DMEM media (Virology, Vol.8, p.396 (1959)), RPMI1640 media (J. Am. Med. Assoc., Vol.199, p.519 (1967)), and 199 media (Proc. Soc. Exp. Biol. Med., Vol.73, p.1 (1950)). The pH of the media is preferably about 6 to 8. Cultivation can be performed usually at about 30 to 40° C. for about 15 to 72 hours with aeration and stirring, if necessary.

[0150] When the host is an insect cell, an example of media is Grace's media containing fetal bovine serum (Proc. Natl. Acad. Sci. USA, Vol.82, p.8404 (1985)). The pH thereof is preferably about 5to 8. Cultivation can be performed usually at about 20 to 40° C. for 15 to 100 hours with aeration and stirring, if necessary.

[0151] The protein of the present invention can be produced as a transmembrane protein by cultivating transformants as mentioned above, in particular animal cells to overexpress the protein of the present invention on the surface of the cells. The protein of the present invention can be produced as a soluble protein fragment such as an extracellular region protein fragment by preparing the transformants as mentioned above using the DNA encoding the extracellular region and by cultivating the transformants to allow them to secrete the soluble polypeptide into the culture supernatant.

[0152] Namely, a culture filtrate (supernatant) is obtained by the method such as filtration or centrifugation of the obtained culture, and the protein of the present invention is purified and isolated from the culture filtrate by the usual method commonly used in order to purify and isolate a natural or synthetic protein.

[0153] Examples of the isolation and purification method are a method utilizing solubility, such as salting out and solvent precipitation method, a method utilizing the difference in molecular weight, such as dialysis, ultrafiltration, gel filtration, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a method utilizing charges, such as ion exchange chromatography and hydroxylapatite chromatography, a method utilizing specific affinity, such as affinity chromatography, a method utilizing the difference in hydrophobicity, such as reverse phase high performance liquid chromatography, and a method utilizing the difference in isoelectric point, such as isoelectric focusing.

[0154] When the protein of the present invention exists in the periplasm or cytoplasm of cultured transformants, first, the fungus bodies or cells are harvested by the usual method such as filtration or centrifugation and suspended in appropriate buffer. After the cell wall and/or cell membrane of the cells and so on are disrupted by the method such as lysis with sonication, lysozyme, and freeze-thawing, the membrane fraction comprising the protein of the present invention is obtained by the method such as centrifugation or filtration. The membrane fraction is solubilized with a detergent such as Triton-X100 to obtain the crude extract. Finally, the polypeptide or the polypeptide fragment is isolated and purified from the crude extract by the usual method as illustrated above.

[0155] The “transgenic mouse” of the present invention is a transgenic mouse wherein the DNA (cDNA or genomic DNA) prepared as mentioned above encoding the protein of the present invention derived from animals except mice (non-self protein) have been integrated into its endogenous locus of the mouse. The transgenic mouse expresses the non-self protein and secretes the protein into its body.

[0156] The transgenic mouse can be prepared according to the method as usually used for producing a transgenic animal (for example, see “Newest Manual of Animal Cell Experiment”, LIC press, Chapter 7, pp.361-408, (1990)).

[0157] Specifically, for example, embryonic stem cells (ES cells) obtained from normal mouse blastocysts are transformed with an expression vector in which the gene encoding human-derived polypeptide of the present invention (i.e. “human JTT-1 antigen”) has been operably inserted. ES cells in which the gene encoding the human-derived polypeptide of the present invention has been integrated into the endogenous gene are screened by the usual method. Then, the ES cells screened are microinjected into a fertilized egg obtained from another normal mouse (blastocyst) (Proc. Natl. Acad. Sci. USA, Vol.77, No.12, pp.7380-7384 (1980); U.S. Pat. No. 4,873,191). The blastocyst is transplanted into the uterus of another normal mouse as the foster mother. Then, founder mice (progeny mice) are born from the foster mother mouse. By mating the founder mice with normal mice, heterogeneic transgenic mice are obtained. By mating the heterogeneic transgenic mice with each other, homogeneic transgenic mice are obtained according to Mendel's laws.

[0158] “Knockout mouse” of the present invention is a mouse wherein the endogenous gene encoding the mouse-derived protein of the present invention has been knocked out (inactivated). It can be prepared, for example, by positive-negative selection method in which homologous recombination is applied (U.S. Pat. No. 5,464,764; U.S. Pat. No. 5,487,992; U.S. Pat. No. 5,627,059; Proc. Natl. Acad. Sci. USA, Vol.86, pp.8932-8935 (1989); Nature, Vol.342, pp.435-438 (1989); etc.).

[0159] The “antibody” of the present invention can be a polyclonal antibody (antiserum) or a monoclonal antibody, and preferably a monoclonal antibody.

[0160] Specifically, it is an antibody reactive to (against, which binds to) the above-mentioned protein or its fragment of the present invention.

[0161] The antibody of the present invention can be natural antibodies obtained by immunizing mammals such as mice, rats, hamsters, guinea pigs, and rabbits with an immunogen (antigen), such as the protein of the present invention (natural, recombinant, or synthetic ones), cells expressing the protein of the present invention, or transformants overexpressing the designed protein on the surface thereof prepared using recombinant DNA technology as described above on the cell surface. The antibody of the present invention also includes chimeric antibodies and humanized antibodies (CDR-grafted antibodies) that can be produced by recombinant DNA technology, and human antibodies that can be produced using human antibody-producing transgenic animals.

[0162] The monoclonal antibody includes those having any one isotype of IgG, IgM, IgA, IgD, or IgE. IgG or IgM is preferable.

[0163] The polyclonal antibody (antisera) or monoclonal antibody of the present invention can be produced by the known methods. Namely, a mammal, preferably, a mouse, rat, hamster, guinea pig, rabbit, cat, dog, pig, goat, horse, or cattle, or more preferably, a mouse, rat, hamster, guinea pig, or rabbit is immunized, for example, with an immunogen (antigen) mentioned above with Freund's adjuvant, if necessary. The polyclonal antibody can be obtained from the antiserum obtained from the animal so immunized. In addition, the monoclonal antibodies are produced as follows. Hybridomas are prepared from the antibody-producing cells obtaind from the animal so immunized and myeloma cells that are not capable of producing autoantibodies. The hybridomas are cloned, and clones producing the monoclonal antibodies showing the specific affinity to the antigen used for immunizing the mammal are screened.

[0164] Specifically, the monoclonal antibody can be produced as follows. Immunizations are performed by injecting or implanting once or several times the protein of the present invention, cells expressing the protein and so on as mentioned above as an immunogen, if necessary, with Freund's adjuvant, subcutaneously, intramuscularly, intravenously, through the footpad, or intraperitoneally into a mouse, rat, hamster, guinea pig, or rabbit, preferably a mouse, rat, or hamster (including a transgenic animal generated so as to produce antibodies derived from another animal such as the transgenic mouse producing human antibody). Usually, immunizations are performed once to four times every one to fourteen days after the first immunization. Antibody-producing cells are obtained from the mammal so immunized in about one to five days after the last immunization.

[0165] Hybridomas that secrete a monoclonal antibody can be prepared by the method of Köhler and Milstein (Nature, Vol.256, pp.495-497 (1975)) and by its modified method. Namely, hybridomas are prepared by fusing antibody-producing cells contained in a spleen, lymph node, bone marrow, or tonsil obtained from the mammal immunized as mentioned above, preferably a spleen, with myelomas without autoantibody-producing ability, which are derived from, preferably, a mammal such as a mouse, rat, guinea pig, hamster, rabbit, or human, or more preferably, a mouse, rat, or human.

[0166] For example, mouse-derived myeloma P3/X63-AG8.653 (653), P3/NSI/1-Ag4-1 (NS-1), P3/X63-Ag8.U1 (P3U1), SP2/0-Ag14 (Sp2/0, Sp2), PAI, F0, or BW5147, rat-derived myeloma 210RCY3-Ag.2.3., or human-derived myeloma U-266AR1, GM1500-6TG-A1-2, UC729-6, CEM-AGR, D1R11, or CEM-T15 can be used as a myeloma used for the cell fusion.

[0167] Hybridoma clones producing monoclonal antibodies can be screened by cultivating hybridomas, for example, in microtiter plates and by measuring the reactivity of the culture supernatant in the well in which hybridoma growth is observed, to the immunogen used for the immunization mentioned above, for example, by enzyme immunoassay such as RIA and ELISA.

[0168] The monoclonal antibodies can be produced from hybridomas by cultivating the hybridomas in vitro or in vivo such as in the ascites fluid of a mouse, rat, guinea pig, hamster, or rabbit, preferably a mouse or rat, more preferably mouse and isolating the antibodies from the resulting the culture supernatant or ascites fluid of a mammal.

[0169] Cultivating hybridomas in vitro can be performed depending on the property of cells to be cultured, on the object of a test study, and on the various conditions of a cultivating method, by using known nutrient media or any nutrient media derived from known basal media for growing, maintaining, and storing the hybridomas to produce monoclonal antibodies in culture supernatant.

[0170] Examples of basal media are low calcium concentration media such as Ham'F12 medium, MCDB153 medium, or low calcium concentration MEM medium, and high calcium concentration media such as MCDB104 medium, MEM medium, D-MEM medium, RPM11640 medium, ASF104 medium, or RD medium. The basal media can contain, for example, sera, hormones, cytokines, and/or various inorganic or organic substances depending on the objective.

[0171] Monoclonal antibodies can be isolated and purified from the culture supernatant or ascites fluid mentioned above by saturated ammonium sulfate precipitation, euglobulin precipitation method, caproic acid method, caprylic acid method, ion exchange chromatography (DEAE or DE52), affinity chromatography using anti-immunoglobulin column or protein A column.

[0172] The “chimeric antibody” of the present invention is a monoclonal antibody prepared by genetic engineering, and specifically means a chimeric antibody such as mouse/human chimeric monoclonal antibody whose variable regions or the other regions are derived from mouse immunoglobulin and whose constant regions are derived from human immunoglobulin.

[0173] The constant region derived from human immunoglobulin has the amino acid sequence inherent in each isotype such as IgG, IgM, IgA, IgD, and IgE. The constant region of the recombinant chimeric monoclonal antibody of the present invention can be that of human immunoglobulin belonging to any isotype. Preferably, it is the constant region of human IgG.

[0174] The chimeric monoclonal antibody of the present invention can be produced, for example, as follows. Needless to say, the production method is not limited thereto.

[0175] A mouse/human chimeric monoclonal antibody can be prepared, referring to Experimental Medicine: SUPPLEMENT, Vol.1.6, No.10 (1988); and examined published Japanese patent application (JP-B) No. Hei3-73280. Namely, it can be prepared by operably inserting CH gene (C gene encoding the constant region of H chain) obtained from the DNA encoding human immunoglobulin downstream of active VH genes (rearranged VDJ gene encoding the variable region of H chain) obtained from the DNA encoding a mouse monoclonal antibody isolated from the hybridoma producing the mouse monoclonal antibody, and CL gene (C gene encoding the constant region of L chain) obtained from the DNA encoding human immunoglobulin downstream of active VL genes (rearranged VJ gene encoding the variable region of L chain) obtained from the DNA encoding the mouse monoclonal antibody isolated from the hybridoma, into the same or different vectors so as for them to be expressed, following by transforming host cells with the expression vector, and then by cultivating the transformants.

[0176] Specifically, DNAs are first extracted from mouse monoclonal antibody-producing hybridomas by the usual method, digested with appropriate restriction enzymes (for example, EcoRI and HindIII), electrophoresed (using, for example, 0.7% agarose gel), and analyzed by Southern blotting. After an electrophoresed gel is stained, for example, with ethidium bromide and photographed, the gel is given with marker positions, washed twice with water, and soaked in 0.25 M HCl for 15 minutes. Then, the gel is soaked in 0.4 N NaOH solution for 10 minutes with gently stirring. The DNAs are transferred to a filter for 4 hours by the usual method. The filter is recovered and washed twice with 2×SSC. After the filter is sufficiently dried, it is baked at 75° C. for 3 hours. After baking, the filter is treated with 0.1×SSC/0.1% SDS at 65° C. for 30 minutes. Then, it is soaked in 3×SSC/0.1% SDS. The filter obtained is treated with prehybridization solution in a plastic bag at 65° C. for 3 to 4 hours.

[0177] Next, 32P-labeled probe DNA and hybridization solution are added to the bag and reacted at 65° C. about 12 hours. After hybridization, the filter is washed under appropriate salt concentration, reaction temperature, and time (for example, 2×SSC-0.1% SDS, room temperature, 10 minutes). The filter is put into a plastic bag with a little 2×SSC, and subjected to autoradiography after the bag is sealed.

[0178] Rearranged VDJ gene and VJ gene encoding H chain and L chain of a mouse monoclonal antibody are identified by Southern blotting mentioned above. The region comprising the identified DNA fragment is fractioned by sucrose density gradient centrifugation and inserted into a phage vector (for example, Charon 4A, Charon 28, &lgr;EMBL3, &lgr;EMBL4, etc.). E. coli (for example, LE392, NM539, etc.) is transformed with the phage vector to generate a genomic library. The genomic library is screened by plaque hybridization such as Benton-Davis method (Science, Vol.196, pp.180-182 (1977)) using appropriate probes (H chain J gene, L chain (&kgr;) J gene, etc.) to obtain positive clones comprising rearranged VDJ gene or VJ gene. By making the restriction map and determining the nucleotide sequence of the clones obtained, it is confirmed that genes comprising the desired, rearranged VH (VDJ) gene or VL (VJ) gene are obtained.

[0179] Separately, human CH gene and human CL gene used for chimerization are isolated. For example, when a chimeric antibody with human IgGl is produced, C&ggr;1 gene as a CH gene, and C&kgr; gene as a CL gene, are isolated. These genes can be isolated from human genomic library with mouse C&ggr;1 gene and mouse C&kgr; gene, corresponding to human C&ggr;1 gene and human C &kgr; gene, respectively, as probes, taking advantage of high homology between the nucleotide sequences of mouse immunoglobulin gene and that of human immunoglobulin gene.

[0180] Specifically, DNA fragments comprising human C&kgr; gene and an enhancer region are isolated from human &lgr; Charon 4A HaeIII-AluI genomic library (Cell, Vol.15, pp.1157-1174 (1978)), for example, with a 3 kb HindIII-BamHI fragment of clone Ig146 (Proc. Natl. Acad. Sci. USA, Vol.75, pp.4709-4713 (1978)) and a 6.8 kb EcoRI fragment of clone MEP10 (Proc. Natl. Acad. Sci. USA, Vol.78, pp.474-478 (1981)) as probes. In addition, for example, after human fetal hepatocyte DNA is digested with HindIII and fractioned by agarose gel electrophoresis, a 5.9 kb fragment is inserted into &lgr;788 and then human C&ggr;1 gene is isolated with the probes mentioned above.

[0181] Using mouse VH gene, mouse VL gene, human CH gene, and human CL gene so obtained, and taking promoter region and enhancer region into consideration, human CH gene is inserted downstream mouse VH gene and human CL gene is inserted downstream mouse VL gene into an expression vector such as pSV2gpt or pSV2neo with appropriate restriction enzymes and DNA ligase by the usual method. In this case, chimeric genes of mouse VH gene/human CH gene and mouse VL gene/human CL gene can be respectively inserted in the same expression vector or in different expression vectors.

[0182] Chimeric gene-inserted expression vector(s) thus prepared are introduced into myelomas that do not produce antibodies, for example, P3X63•Ag8•653 cells or SP210 cells by protoplast fusion method, DEAE-dextran method, calcium phosphate method, or electroporation method. The transformants are screened by cultivating in media containing a drug corresponding to the drug resistance gene inserted into the expression vector and, then, cells producing desired chimeric monoclonal antibodies are obtained.

[0183] Desired chimeric monoclonal antibodies are obtained from the culture supernatant of antibody-producing cells thus screened.

[0184] The “humanized antibody (CDR-grafted antibody)” of the present invention is a monoclonal antibody prepared by genetic engineering and specifically means a humanized monoclonal antibody wherein a portion or the whole of the complementarity determining regions of the hypervariable region are derived from the complementarity determining regions of the hypervariable region from a mouse monoclonal antibody, the framework regions of the variable region are derived from the framework regions of the variable region from human immunoglobulin, and the constant region is derived from human a constant region from immunoglobulin.

[0185] The complementarity determining regions of the hypervariable region exists in the hypervariable region in the variable region of an antibody and means three regions which directly and complementary binds to an antigen (complementarity-determining residues, CDR1, CDR2, and CDR3). The framework regions of the variable region means four comparatively conserved regions lying upstream, downstream or between the three complementarity determining regions (framework region, FR1, FR2, FR3, and FR4).

[0186] In other words, a humanized monoclonal antibody means that in which the whole region except a portion or the whole of the complementarity determining regions of the hypervariable region of a nonhuman mammal-derived monoclonal antibody have been replaced with their corresponding regions derived from human immunoglobulin.

[0187] The constant region derived from human immunoglobulin has the amino acid sequence inherent in each isotype such as IgG (IgG1, IgG2, IgG3, IgG4), IgM, IgA, IgD, and IgE. The constant region of a humanized monoclonal antibody in the present invention can be that from human immunoglobulin belonging to any isotype. Preferably, it is the constant region of human IgG. The framework regions of the constant region derived from human immunoglobulin are not particularly limited.

[0188] The humanized monoclonal antibody of the present invention can be produced, for example, as follows. Needless to say, the production method is not limited thereto.

[0189] For example, a recombinant humanized monoclonal antibody derived from mouse monoclonal antibody can be prepared by genetic engineering, referring to unexamined Japanese patent publication (JP-WA) No. Hei 4-506458 and unexamined Japanese patent publication (JP-A) No. Sho 62-296890. Namely, at least one mouse H chain CDR gene and at least one mouse L chain CDR gene corresponding to the mouse H chain CDR gene are isolated from hybridomas producing mouse monoclonal antibody, and human H chain gene encoding the whole regions except human H chain CDR corresponding to mouse H chain CDR mentioned above and human L chain gene encoding the whole region except human L chain CDR correspond to mouse L chain CDR mentioned above are isolated from human immunoglobulin genes.

[0190] The mouse H chain CDR gene(s) and the human H chain gene(s) so isolated are operably inserted into an appropriate vector so that they can be expressed. Similarly, the mouse L chain CDR gene(s) and the human L chain gene(s) are operably inserted into another appropriate vector so that they can be expressed. Alternatively, the mouse H chain CDR gene(s)/human H chain gene(s) and mouse L chain CDR gene(s)/human L chain gene(s) can be operably inserted into the same expression vector so that they can be expressed. Host cells are transformed with the expression vector thus prepared to obtain transformants producing humanized monoclonal antibody. By cultivating the transformants, desired humanized monoclonal antibody is obtained from culture supernatant.

[0191] The “human monoclonal antibody” of the present invention is immunoglobulin in which the entire regions comprising the variable and constant region of H chain, and the variable and constant region of L chain constituting immunoglobulin are derived from the gene encoding human immunoglobulin.

[0192] The human antibody can be produced in the same way as the production method of polyclonal or monoclonal antibodies mentioned above by immunizing, with an antigen, a transgenic animal which for example, at least human immunoglobulin gene(s) have been integrated into the locus of a non-human mammal such as a mouse by the usual method. For example, a transgenic mouse producing human antibodies is prepared by the methods described in Nature Genetics, Vol.15, pp.146-156 (1997); Nature Genetics, Vol.7, pp.13-21 (1994); JP-WA Nos. Hei4-504365, International patent publication No. WO94/25585; Nikkei Science, No.6, pp.40-50 (1995); Nature, Vol.368, pp.856-859 (1994);and JP-WA No. Hei 6-500233.

[0193] The “portion of an antibody” used in the present invention means a partial region of the antibody, preferably monoclonal antibody of the present invention as mentioned above, and specifically, means F(ab′)2, Fab′, Fab, Fv (variable fragment of antbody), sFv, dsfv (disulfide stabilized Fv),or dAb (single domain antibody) (Exp. Opin. Ther. Patents, Vol.6, No.5, pp.441-456 (1996)). “F(ab′)2” and “Fab′” can be produced by treating immunoglobulin (monoclonal antibody) with a protease such as pepsin and papain, and means an antibody fragment generated by digesting immunoglobulin near the disulfide bonds existing between the hinge regions in each of the two H chains. For example, papain cleaves IgG upstream of the disulfide bonds existing between the hinge regions in each of the two H chains to generate two homologous antibody fragments in which an L chain composed of VL (L chain variable region) and CL (L chain constant region), and an H chain fragment composed of VH (H chain variable region) and CH&ggr;1 (&ggr;1 region in the constant region of H chain) are connected at their C terminal regions through a disulfide bond. Each of such two homologous antibody fragments is called Fab′. Pepsin also cleaves IgG downstream of the disulfide bonds existing between the hinge regions in each of the two H chains to generate an antibody fragment slightly larger than the fragment in which the two above-mentioned Fab′ are connected at the hinge region. This antibody fragment is called F(ab′)2.

[0194] The “pharmaceutical composition” of the present invention comprises any one of the protein, protein fragment, fusion protein antibody, or portion of an antibody of the present invention as defined above; and a pharmaceutically acceptable carrier.

[0195] The “pharmaceutically acceptable carrier” includes a excipieut, a diluent, an expander, a decomposition agent, a stabilizer, a preservative, a buffer, an emulsifier, an aromatic, a colorant, a sweetener, a viscosity increasing agent, a flavor, a solubility increasing agent, or other additives. Using one or more of such carriers, a pharmaceutical composition can be fomulated into tablets, pills, powders, granules, injections, solutions, capsules, troches, elixirs, suspensions, emulsions, or syrups. The pharmaceutical composition can be administered orally or parenterally. Other forms for parenteral administration include a solution for external application, suppository for rectal administration, and pessary, prescribed by the usual method, which comprises one or more active ingredient.

[0196] The dosage can vary depending on the age, sex, weight, and symptom of a patient, effect of treatment, administration route, period of treatment, or the kind of active ingredient (polypeptide or antibody mentioned above) contained in the pharmaceutical composition. Usually, the pharmaceutical composition can be administered to an adult in a dose of 10 &mgr;g to 1000 mg (or 10 &mgr;g to 500 mg) per one administration. Depending on various conditions, the dosage less than that mentioned above may be sufficient in some cases, and the dosage more than that mentioned above may be necessary in other cases.

[0197] In particular, the injection can be produced by dissolving or suspending the antibody in a non-toxic, pharmaceutically acceptable carrier such as physiological saline or commercially available distilled water for injection with adjusting a concentration to 0.1 &mgr;g antibody/ml carrier to 10 mg antibody/ml carrier. The injection thus produced can be administered to a human patient in need of treatment in a dose of 1 &mgr;g to 100 mg/kg body weight, preferably 50 &mgr;g to 50 mg/kg body weight once or more times a day. Examples of administration route are medically appropriate administration routes such as intravenous injection, subcutaneous injection, intradermal injection, intramuscular injection, or intraperitoneal injection, preferably intravenous injection.

[0198] The injection can also be prepared into a non-aqueous diluent (for example, propylene glycol, polyethylene glycol, vegetable oil such as olive oil, and alcohol such as ethanol), suspension, or emulsion.

[0199] The injection can be sterilized by filtration with a bacteria-non-penetrated filter, by mixing bacteriocide, or by irradiation. The injection can be produced in the form that is prepared upon use. Namely, it is freeze-dried to be a sterile solid composition, and can be dissolved in sterile distilled water for injection or another solvent before use.

[0200] The pharmaceutical composition of the present invention can be used to treat or prevent arteriosclerosis and restenosis after the treatment of artery occlusion, such as PTCA.

BRIEF DESCRIPTION OF THE DRAWINGS

[0201] FIG. 1 is a photograph showing an electrophoresis image of rabbit BA2303 cDNA samples obtained by RT-PCR.

[0202] The numerals indicate days from the exfoliation of the artery endothelium using a balloon catheter to the removal of the artery; thus, the figure shows the time course of the cDNA expression.

[0203] FIG. 2 is a photograph showing an electrophoresis image of rabbit BA0306 cDNA samples obtained by RT-PCR.

[0204] The numerals indicate days from the exfoliation of the artery endothelium using a balloon catheter to the removal of the artery; thus, the figure shows the time course of the cDNA expression.

[0205] FIG. 3 shows a plot of the hydrophobicity and hydrophilicity of the amino acid residues composing rabbit BA2303 protein.

[0206] FIG. 4 shows a plot of the hydrophobicity and hydrophilicity of the amino acid residues composing human BA0306 protein.

[0207] FIG. 5 shows a plot of the hydrophobicity and hydrophilicity of the amino acid residues composing human BA2303 protein.

[0208] FIG. 6 is a photograph showing the result of Northern blot analysis of the expression of human BA2303 mRNA in various human tissues.

[0209] FIG. 7 is a photograph showing the result of Northern blot analysis of the expression of human BA0306 mRNA in various human tissues.

[0210] FIG. 8 shows a plot of the hydrophobicity and hydrophilicity of the amino acid residues composing mouse BA2303 protein.

[0211] FIG. 9 shows the sequence homology at the amino acid level between BA2303 proteins from rabbit, human, and mouse.

[0212] FIG. 10 shows the sequence homology at the amino acid level between BA0306 proteins from rabbit, human, and mouse.

[0213] FIG. 11 schematically shows the structures of mouse genomic DNA containing exons that encode mouse BA2303 protein, and of the targeting vector for knockout mice generation.

[0214] FIG. 12 schematically shows the structures of mouse genomic DNA containing exons that encode mouse BA0306 protein, and of the targeting vector for knockout mice generation.

BEST MODE FOR IMPLEMENTING THE INVENTION

[0215] The present invention is illustrated in detail below with reference to examples, but is not to be construed as being limited thereto.

EXAMPLE 1

Generation of a Rabbit Model Whose Aortal Endothelium is Detached by PTCA

[0216] According to the method described in “Protocols in Circulation Research” (Jikken-Igaku Zoukan (1996) Vol.14 (12), 87), a balloon catheter was inserted into the thoracic artery of Japanese white rabbits by surgical operation and was inflated to perform PTCA. The artery including the operation site was removed at certain periods from day 1 to six months after PTCA.

EXAMPLE 2

Preparation of Total RNA from Removed Aortae

[0217] The aorta was removed at 1, 2, 4, 7, 14, 23, 30, 54, 112, and 137 days after PTCA, and total RNA was prepared from the aortae by the standard method using the TRIZOL reagent (GIBCO BRL).

[0218] Also, the aorta was removed from a normal Japanese white rabbit, which was not subjected to PTCA, and total RNA was prepared as described.

EXAMPLE 3

cDNA Synthesis

[0219] Total RNAs (each 2 &mgr;l, 1 &mgr;g/ml) sampled with the passage of time or mRNA samples (each 2 &mgr;l, 0.5 &mgr;g/ml), which were obtained in Example 2, were dissolved in diethyl pirocarbonate (DEPC)-treated distilled water (8 &mgr;l). Anchor primer (GT15MA, 1 &mgr;l, 25 pmol/&mgr;l) was added to make the total volume 10&mgr;l, and the mixture was then incubated 5 min at 65° C. The samples were placed on ice immediately after completion of the incubation.

[0220] Then, 5×first strand buffer (4 &mgr;l, composition: 0.25 M Tris-HCl (pH 7.5), 0.375 M KCl, 0.05 M DTT, 0.015 M MgCl2), 0.1 M DTT (2 &mgr;l), 250 &mgr;M dNTP (1 &mgr;l), distilled water (1 &mgr;l), and reverse transcriptase (Superscript, GIBCO BRL, 1 &mgr;l, 200 U/&mgr;l) were added to make the total volume20 &mgr;l. cDNA was synthesized by incubating the reaction mixture for 1 hr at 42° C., and then DEPC-treated water (30 &mgr;l) was added to make the final volume 50 &mgr;l.

EXAMPLE 4

Analysis of the Time Course of Gene Expression

[0221] The time course of gene expression after PTCA was analyzed by the standard method using differential display (Nucleic Acid Research (1993) Vol. 21(18), 4272-4280; Science (1992) Vol. 257, 967-971), and RT-PCR (reverse transcription-polymerase chain reaction; “PCR and its Application” (Jikken-Igaku Zoukan (1990) Vol. 8(9); “Gene Amplification PCR Method/Principles and Novel Applications” Kyoritsu-Syuppan (1992)).

[0222] One hundred-fold dilution of the cDNA samples (each time point) which were prepared in Example 3 was used as a template for PCR in differential display. Fifty fold dilution was used for cDNA samples that were synthesized from mRNA (each time point).

[0223] The template cDNA (each 2 &mgr;l) was mixed with distilled water (10.75 &mgr;l), 10×EX Taq buffer (2 &mgr;l), 25 &mgr;M dNTP (1.5 &mgr;l), arbitrary primer (sequence: GATCAATCGC, 1 &mgr;l, 25pmol/&mgr;l), anchor primer (1 &mgr;l, 25 pmol/&mgr;l), EX Taq DNA polymerase (0.25 &mgr;l), and &agr;35S-dATP (1.5 &mgr;l, 10 mCi/ml, Amersham) to make the total volume 20 &mgr;l. PCR was carried out with a cycle of 95° C. for 3 min, 40° C. for 5 min, 72° C. for 5 min; 40 cycles of 95° C. for 30 sec, 40° C. for 2 min, 72° C. for 1 min; and a step of 72° C. for 5 min, and then the samples were kept at 4° C.

[0224] Each of the resulting PCR products was mixed with stop buffer (5 &mgr;l, composition: formamide (30 ml), xylenecyanol (30 mg), bromophenol blue (10 mg), 0.5 M EDTA (200 &mgr;l, (pH 8.0)), and then, 3.5 &mgr;l of each resulting mixture was subjected to sequence gel electrophoresis on a 6% acrylamide gel (composition (in 500 ml total): urea (240 g), 10×TBE (50 ml), 40% acrylamide (75 ml, a mixture of 38% monoacrylamide and 2% bisacrylamide)). The result showed that there were two bands whose expression was changed in the time course.

[0225] Both bands were excised from the gel, and two DNA fragments containing the nucleotide sequences described in SEQ ID NO: 11 (178 bp) and SEQ ID NO: 12 (167 bp) were isolated according to the standard method (“Gene Engineering Handbook” Jikken-Igaku, Yodosya (1992)). The fragments were named as BA2303 (SEQ ID NO: 11), and BA0306 (SEQ ID NO: 12), respectively. To confirm the expression of the DNAs containing the two fragments in the time course, RT-PCR was performed using cDNA samples obtained in Example 3 (each time point) as a template.

[0226] For amplification of BA2303, synthetic DNA fragments described in SEQ ID NO: 13 and SEQ ID NO: 14 were used as forward and reverse primers, respectively.

[0227] For amplification of BA0306, synthetic DNA fragments described in SEQ ID NO: 21 and SEQ ID NO: 22 were used as forward and reverse primers, respectively.

[0228] Each template cDNA (3 &mgr;l) was mixed with 1033 Vogelstein buffer (2.5 &mgr;l), 2.5 mM dNTP (1.5 &mgr;l), forward primer (1 &mgr;l, 25 pmol/&mgr;l), reverse primer (1 &mgr;l, 25 pmol/&mgr;l), &bgr;-actin primer mix (each 25 pmol/&mgr;l), and EX Taq DNA polymerase (0.2 &mgr;l), adjusting the total volume to 25 &mgr;l. RT-PCR was carried out with a step of 94° C. for 2 min; 35 cycles of 94° C. for 3 sec, 55° C. for 30 sec, 72° C. for 1 min; and a step of 72° C. for 3 min, and then the samples were kept at 4° C.

[0229] The obtained PCR products were separated by electrophoresis. The results were shown in FIGS. 1 (BA2303) and 2 (BA0306).

[0230] It was confirmed that the expression of BA2303 was increased from day 1 after the vascular endothelium was detached by PTCA, reached the maximal level from about day 2 to day 4, and continued until about day 7. The expression of BA0306 was detected over a period from day 1 to day 7 after PTCA, with peak expression at day 4.

EXAMPLE 5

Isolation of Long Strand cDNA

[0231] To isolate long strand cDNAs containing the two cDNA fragments (BA2303 and BA0306) obtained in Example 4, RACE (rapid amplification ends)-PCR was performed (Proc. Natl. Acad. Sci. USA (1988) Vol. 85, 8998-9002; “PCR Method for Gene Amplification/Principles and Novel Applications” Kyoritsu-Syuppan (1992)).

[0232] The PCR was performed twice using the Marathon cDNA Amplification Kit (CLONTECH) and the cDNA fragments obtained in Example 4 as a template.

[0233] BA2303 was amplified by PCR using synthetic DNA primers 5 described in SEQ ID NO: 15 and SEQ ID NO: 19 (1), and with primers described in SEQ ID NO: 16 and SEQ ID NO: 20 (2), and subsequently using synthetic DNA primers described in SEQ ID NO: 17 and SEQ ID NO: 19 (3), and with primers described in SEQ ID NO: 18 and SEQ ID NO: 20 (4).

[0234] BA0306 was amplified by PCR using synthetic DNA primers described in SEQ ID NO: 23 and SEQ ID NO: 19 (1), and with primers described in SEQ ID NO: 24 and SEQ ID NO: 20 (2), and subsequently using synthetic DNA primers described in SEQ ID NO: 25 and SEQ ID NO: 19 (3), and with primers described in SEQ ID NO: 26 and SEQ ID NO: 20 (4). The above PCR produced DNAs described in SEQ ID NO: 1 (BA2303) and in SEQ ID NO: 7 (BA0306).

[0235] Analysis of the deduced amino acid sequence by plotting the hydrophilicity and hydrophobicity and by PSORT program suggested that BA2303 is a protein having seven transmembrane regions (FIG. 3).

EXAMPLE 6

Isolation of Human Counterpart Genes

[0236] The rabbit cDNAs (BA2303 and BA0306) obtained in Example 5 were used as a probe to screen a human cDNA library (Fetal Brain, STRATAGENE, code:937-227) by colony hybridization according to the standard method (“Gene Engineering HandBook” Jikken-Igaku Zokan, Yodosya, (1992)). Thus, human homologues containing the nucleotide sequences described in SEQ ID NO: 3 (BA2303) and in SEQ ID NO: 9 (BA0306) were obtained.

[0237] Analysis of the deduced amino acid sequence of BA0306 protein by plotting the hydrophilicity and hydrophobicity and by PSORT program suggested that the protein has 10 transmembrane regions (FIG. 4). It is also suggested that human BA2303 is a protein having seven transmembrane regions as is the rabbit one obtained in Example 5 (FIG. 5).

[0238] Using the respective human DNA as a probe, the expression of mRNA of the two genes in various human tissues was examined using the Human Multiple Tissue Northern Blot (CLONTECH, code: #7760-1, #7759-1).

[0239] BA2303 mRNA was expressed in various human tissues as evident as two bands of about 3.9 kb and about 2.1 kb (FIG. 6).

[0240] BA0306 mRNA was also expressed in various human tissues as detected as two bands of about 3.5 kb and about 4.4 kb (FIG. 7).

[0241] Homology search between known proteins indicated that human BA0306 has sequence homology at the amino acid level with S. cerevisiae oxidative stress resistance protein, S. cerevisiae zinc/cadmium resistance protein, and heavy metal ion resistance protein, etc.

EXAMPLE 7

Isolation of Mouse BA2303 cDNA

[0242] As was described in Example 6, rabbit BA2303 gene was used as a probe for screening a mouse cDNA library (STRATAGENE, code: 936-309), and the mouse homologue containing the nucleotide sequence described in SEQ ID NO: 5 was isolated. The deduced amino acid sequence of the coding region was described in SEQ ID NO: 6.

[0243] Analysis of the deduced amino acid sequence by plotting the hydrophilicity and hydrophobicity and by PSORT program suggested that mouse BA2303 protein has seven transmembrane regions as do rabbit and human BA2303 (FIG. 8).

[0244] BA2303 proteins of the present invention, from rabbit, human and mouse, have a high sequence homology at the amino acid level between each other (FIG. 9). EXAMPLE 8

Isolation of Mouse BA0306 cDNA

[0245] As was described in Example 6, rabbit BA0306 gene was used as a probe for screening a mouse cDNA library (STRATAGENE, code: 936-309), and the mouse homologue containing the nucleotide sequence described in SEQ ID NO: 27 was isolated. The deduced amino acid sequence of the coding region was described in SEQ ID NO: 28.

[0246] BA0306 proteins of the present invention, from rabbit, human and mouse, have a high sequence homology at the amino acid level with each other (FIG. 10).

EXAMPLE 9

Preparation of Anti-peptide Antibody Against Human BA2303

[0247] An oligopeptide (Gln-Asp-Ala-Gln-Gly-Gln-Arg-Ile-Gly-His-Phe-Glu-Phe-His-Gly) containing amino acid residues from 35 to 49 in the sequence described in SEQ ID NO: 4 was synthesized. Two rabbits were immunized three times with peptide and Freund's complete adjuvant. The rabbit sera obtained after each immunization were subjected to ELISA using horse radish peroxidase-conjugated goat anti-rabbit IgG and microplates having wells coated with the peptide (1 &mgr;g/well), and the fluorescence intensity was measured at 492 nm to determine the antibody titers. Titers were determined as dilution of sera to obtain a fluorescence intensity at 492 nm not more than 0.2. The result showed that the titers of antisera taken from a rabbit A were 50-fold or less before immunization (3 to 5 ml), 30,600-fold after the first immunization (16 ml), 40,900-fold after the second immunization (25 ml), and 41,100-fold after the third immunization (23 ml), indicating that the titer was increased with the number of immunization. The titers of antisera from the other rabbit B were not more than 50-fold before immunization (3 to 5 ml), 149,200- fold after the first immunization (25 ml), 327,500-fold after the second immunization (25 ml), and 500,000-fold or more after the third immunization (25 ml), indicating that the titer was increased and that antibody against the peptide was produced.

[0248] Next, the forth immunization was performed on both rabbits A and B. The titers after the forth immunization were 46,500-fold in rabbit A, and 500,000-fold or more in rabbit B as was after the third immunization. Then, the antisera taken from rabbit A after the forth immunization were purified by affinity chromatography using a column absorbed with the peptide that had been used as an antigen. The titer of the sera from rabbit A after purification was 69,800-fold.

EXAMPLE 10

Preparation of Recombinant Fusion Protein with Human BA2303 Protein

[0249] Fusion proteins of the present invention were prepared as a fusion protein with maltose binding protein (MBP) using the expression plasmid pMAL-C2 (New England Bio Labs. (NEB)), which contains a DNA encoding MBP. Experimental procedures were performed according to the manufacturer's instructions (Catalogue number: #800, ‘Protein Fusion & Purification System’ Ver. 3.03, 12/1994 revised) and by the standard method of recombinant DNA technology.

[0250] Using a template of the DNA encoding human BA2303 (SEQ ID NO: 3), which was cloned in the previous Example, a DNA containing the nucleotide sequence corresponding to the N-terminal amino acids (residues 22 (Gly) to 171 (His)), having EcoRI and HindIII restriction sites at 5′ and 3′ termini, respectively, was amplified by PCR according to the standard method. Oligonucleotides described in SEQ ID NO: 29 and SEQ ID NO: 30 were used as 5′ and 3′ primers, respectively. The above pMAL-C2 expression plasmid (NEB, inserted with a DNA encoding MBP) was digested with EcoRI and HindIII, and the resulting fragments were recovered. Using a commercially available DNA ligation kit, the above PCR products of human BA2303 were ligated into the pMAL-C2, and the resulting plasmid was used to transfected E. coli TB1 cells. The bacterial expression plasmid was prepared in a large quantity from the transformed colony. A culture of the transformed colony ({fraction (1/100)} volume) was inoculated into 1 liter of LB broth containing ampicillin and glucose, and incubated with shaking until the OD value became up to 0.5. Then, isopropanol-&bgr;-D-thiogalactopyranoside (IPTG) was added to the culture to the final concentration of 0.3 mM, and shaking culture was performed further (3 hr). The culture was then centrifuged to remove the supernatant, and the precipitated bacteria was resuspended in cold column buffer (50 ml, composition: 20 mM Tris-HCl, 200 mM NaCl, 1 mM EDTA, and 10 mM mercaptoethanol), which was supplemented with 0.1 M PMSF (50 &mgr;l, phenylmethylsulfonyl fluoride) to suppress protease digestion.

[0251] The following procedures were carried out on ice unless otherwise noted. The obtained bacteria suspension was sonicated on ice to disrupt cells. Then, the suspension was centrifuged (9000 rpm, 15 to 30 min) to recover soluble fraction. The soluble fraction was diluted with ice-cold column buffer to load on a column.

[0252] Amylose resin (15 ml, BIORAD) was packed in a disposable column (2.5 dia.×10 cm), washed, and equilibrated with 8 volumes of ice-cold column buffer. The sample was loaded onto the column using a pump to keep the flow rate 1 ml/min, and washed with ice-cold column buffer.

[0253] The fusion protein was eluted and fractionated with ice-cold column buffer containing 10 mM maltose. Each fraction was separated by SDS-PAGE, and analyzed by western blotting using antisera against MBP (NEB). Fractions producing a band detected by western blotting at the position approximately corresponding to that of the full-length fusion protein were determined to be positive. Next, the positive fractions were further purified. MBP/BA2303 fusion protein can be digested by adding 1 mg/ml factor Xa (5 &mgr;l) to the solution containing the fusion protein and incubating it for 24 hr. Digestion of the fusion protein can be determined by SDS-PAGE followed by western blotting using antisera against MBP.

EXAMPLE 11

Preparation of Antibody Against Human BA2303 Protein

[0254] Recombinant protein prepared in Example 10, containing approximately 150 N-terminal amino acids of human BA2303 protein (residues 22 (Gly) to 171 (His)), was used as an immunogen. Two rabbits were immunized with the recombinant protein and Freund's complete adjuvant. The rabbit sera was subjected to ELISA using horse radish peroxidase-conjugated goat anti-rabbit IgG and microplates having wells coated with the peptide (1 &mgr;g/well), and the fluorescence intensity was measured at 492 nm to determine the antibody titers. The titer was determined as dilution of serum to obtain a fluorescence intensity at 492 nm not more than 0.2. The result showed that the titer of sera taken from a rabbit was 50-fold or less before immunization (3to 5 ml), and 316,900- fold after immunization (18 ml), indicating that the titer was increased. The titer of the sera from the other rabbit was less than 50-fold before immunization (3 to 5 ml), and increased to 312,300-fold after immunization (23 ml), indicating that antibody against the recombinant protein was produced.

EXAMPLE 12

Construction of an Expression Vector for Recombinant Human BA2303

[0255] Using a template of the DNA encoding human BA2303 (SEQ ID NO: 3), which was cloned in the previous Example, a DNA containing the nucleotide residues 77 to 1419 (containing the entire open reading frame (ORF)), having XbaI restriction sites at both 5′ and 3′ termini, was amplified by PCR according to the standard method. Oligonucleotides described in SEQ ID NO: 31 and in SEQ ID NO: 32 were used as 5′ and 3′ primers, respectively.

[0256] The resulting PCR products were ligated into the XbaI site of the pcDNA expression plasmid (Invitrogen) using a commercially available DNA ligation kit to construct an expression vector for recombinant human BA2303. Higher eukaryotic host cells such as COS cells can be transfected with the vector, and the resulting colonies are selected to obtain transfected cells. Human BA2303 proteins can be expressed abundantly on the cell surface of the transfected cells by incubating the them in appropriate medium such as DMEM containing 10% FCS.

EXAMPLE 13

Preparation of Recombinant Rabbit BA0306 Protein

[0257] Using a template of the DNA encoding rabbit BA0306 (SEQ ID NO: 7), which was cloned in the previous Example, a DNA containing the nucleotide residues 2017 (Ile) to 2196 (Met), having BamHI and SalI restriction sites at 5′ and 3′ termini, respectively, was amplified by PCR according to the standard method. In the amino acid sequence (60 residues) encoded by the rabbit nucleotide sequence (nucleotides 2017 (Ile) to 2196 (Met)), 58 residues are the same as those in the corresponding human BA0306 sequence (residues 535 to 594 in SEQ ID NO: 10). Oligonucleotides described in SEQ ID NO: 33 and in SEQ ID NO: 34 were used as 5′ and 3′ primers, respectively.

[0258] The expression plasmid pQE-32 (QIA expression type IV construct, QIAGEN) was digested with BamHI and SalI, and then blunted.

[0259] According to the instruction manual for handling pQE-32, the obtained PCR products were ligated into the blunted ends of pQE-32 digested with BamHI-SalI using a commercially available DNA ligation kit. The resulting expression vector for recombinant human BA0306 was named as pQE-32R7-15.

[0260] Next, E. coli cells (XL-1 blue MRF') were transformed with the pQE-32R7-15 according to the standard method, and the transformed colonies were selected (“Gene Engineering Handbook” Jikken-Igaku Bessatsu, Yodosha (1992) 46-51). A culture of the transformed cells was inoculated into LB broth containing ampicillin and glucose, and incubated at 37° C. with shaking, with measuring the OD. Then, IPTG (isopropanol-&bgr;-D-thiogalactopyranoside) was added to the culture to the final concentration of 1 mM, and shaking culturing was further performed at 37° C. for 4 hrs. The culture was centrifuged to remove the supernatant, and the precipitated bacteria was resuspended in column buffer. The suspension was sonicated on ice to disrupt cells, then centrifuged, and soluble fraction was recovered. The soluble fraction was diluted with ice-cold column buffer to load on a column.

[0261] A column was packed with Ni-NTA resin, washed, and equilibrated with column buffer. The samples were applied on the column and washed with column buffer. The eluted fractions were collected, and thus recombinant rabbit BA0306 protein was obtained.

EXAMPLE 14

Preparation of Antibody Against Human BA0306

[0262] Recombinant rabbit BA0306 protein prepared in Example 13 was used as an immunogen. The protein and Freund's complete adjuvant were used to immunize chickens. The chicken sera were subjected to ELISA using horse radish peroxidase-conjugated anti-chicken IgG and microplates having wells coated with the recombinant protein (1 &mgr;g/well), and the fluorescence intensity was measured to determine the antibody titers. The result showed that the titer was increased, indicating that antibody against the ecombinant protein was produced.

[0263] Furthermore, rabbit BA0306 protein fragment, which was used as an immunogen in this example, and the above recombinant human BA0306 protein were detected by western blotting using the chicken antisera, indicating that the antisera had a cross reactivity with human BA0306 protein.

EXAMPLE 15

Generation of Knockout Mice of Mouse BA2303 gene

[0264] A knockout mouse, whose endogenous gene encoding mouse BA2303 protein was inactivated, was generated as follows.

[0265] (1) Construction of a Targeting Vector

[0266] A targeting vector for generation of a knockout mouse, in which an endogenous gene encoding mouse BA2303 protein was inactivated (knocked out) by homologous recombination (Nikkei-Science (1994) May, 52-62), was constructed as follows.

[0267] The cDNA encoding mouse BA2303 protein (SEQ ID NO: 5), which was cloned in the previous Example, was labeled with 32P by the standard method to obtain a probe used in hybridization. The probe was used to screen a cosmid mouse genomic DNA library (“Labomanual Human Genome Mapping” Hori M., and Nakamura Y. edit., Maruzen Syuppan), and thus, a mouse genomic DNA clone containing exons (E1, E2, and E3) which encode mouse BA2303 protein was isolated. The structure of the genomic DNA was schematically shown in FIG. 11. The genomic DNA was subcloned into a plasmid, and digested with SacII to remove the region of 124 bp encompassing E1 and the intron between E1 and E2, and then ligated with an insert of a neomycin resistance gene of 1143bp (neo, as a positive selection marker), which had been digested with restriction enzymes and blunted.

[0268] The plasmid pBluescript II SK(−) was digested with SacII, and ligated with an insert of a thymidine kinase gene (TK, as a negative selection marker). Then, the resulting pBluescript II SK(−) was digested with XbaI, and ligated with an insert of the above mouse BA2303 genomic DNA having a neo gene insertion.

[0269] (2) Transfection of the Targeting Vector into ES Cells

[0270] Mouse embryonic stem cells (ES cells) (Nature (1993) 362, 255-258; Nature (1987) 326, 292-295), which were cultured in DMEM containing 15% fetal bovine serum, were trypsinized to obtain single isolated cells, washed three times in phosphate buffer, and prepared as a cell suspension of 1×107 cells/ml. The targeting vector was added to the cells (25 &mgr;g/1 ml cell suspension), and electroporation was performed with a single pulse of 350 V/cm (25 &mgr;F). Then, the ES cells were seeded into 10 cm dishes (1×107 cells/dish), cultured for one day in maintenance medium, and then the medium was replaced with selection medium (containing G418 (250 &mgr;g/ml) and 2 &mgr;M gancyclovir). The culture was continued with replacing the medium every two days. On the tenth day after transfection of targeting vector, 540 neomycin resistant ES clones were isolated using a micropipet under microscopic observation. The clones were cultured separately in 24 well plates layered with feeder cells, and replica of 540 neomycin resistant ES cells were obtained.

[0271] (3) Screening of Knockout ES Cells

[0272] Each neomycin resistant ES clone was examined by PCR whether its endogenous gene encoding mouse BA2303 protein was inactivated (knocked out) by homologous recombination.

[0273] PCR was performed using genomic DNA extracted from each neomycin resistant ES clone as a template, with two primers designed based on the sequence of the neo gene (SEQ ID NO: 36 and SEQ ID NO: 37) (1) and on the mouse BA2303 genomic DNA sequence which locates on the flanking region of the BA2303 DNA which was inserted in the targeting vector (SEQ ID NO: 35 and SEQ ID NO: 38) (2). DNA was purified using an automated DNA purification robot (Kubota). The result showed that desired PCR products were obtained in several clones among the ES clones examined. Further selection of these clones can be performed by genomic Southern blotting. Genomic DNA was extracted from each clone, digested with restriction enzymes, and separated by electrophoresis on an agarose gel. Then, the DNA was transferred onto a nylon membrane, and subjected to hybridization using a probe designed based on the genomic sequence of mouse BA2303. The probe was designed based on the sequence which locates in the flanking region of the site of homologous recombination, and thus enabled to distinguish mutated genome from normal one by size. The knockout ES clone selected in this way was used for generation of knockout mice as described below.

[0274] (4) Generation of Knock Out Mice

[0275] The above obtained ES cells, having inactivation in the endogenous gene encoding mouse BA2303 protein as a result of homologous recombination, were injected into blastocysts obtained by crossing C57BL6 mice (Japan Charles River) (15 cells/embryo, microinjection). Immediately after microinjection, the blastocysts were implanted into uterines of ICR mice (Clea Japan), which had undergone pseudopregnancy treatment two days and half before (10 blastocysts/one side of the uterine). Thus, desired chimera mice were obtained. The chimera were crossed with normal C57BL6 mice to obtain agouti mice, whose color is attributed to a gene determining hair color, originating from ES cells.

EXAMPLE 16

Generation of Knockout Mice of Mouse BA0306 Gene

[0276] (1) Construction of a Targeting Vector.

[0277] A targeting vector for generation of a knockout mouse, in which the endogenous gene encoding mouse BA0306 protein was inactivated (knocked out) by homologous recombination (Nikkei-Science (1994) May, 52-62), was constructed as follows.

[0278] The cDNA encoding mouse BA0306 protein (SEQ ID NO: 27), which was cloned in the previous Example, was labeled with 32p by the standard method to obtain a probe used in hybridization. The probe was used to screen a 129SVJ mouse genomic DNA library (STRATAGENE), and a mouse genomic DNA clone containing exons (exon I, II, III, IV, and V) that encode mouse BA0306 protein was isolated.

[0279] The plasmid pBluescript II SK(−) was digested with XhoI and HindIII, and ligated with XhoI-HindIII-digested thymidine kinase gene (TK, as a negative selection marker). Next, NotI-digested pBluescript II SK(−) was ligated with an insert of the above mouse BA0306 genomic DNA (exons I to V). Then, the neomycin resistance gene (neo, as a positive selection marker) was digested with BamHI and XhoI, blunted, and ligated into the Aor51HI site of the exon V in the mouse BA0306 genomic DNA. Finally, the resulting pBluescript II SK(−) was digested with SacII and linealized to use as a targeting vector.

[0280] (2) Transfection of the Targeting Vector into ES Cells.

[0281] Mouse embryonic stem cells (ES cells, 1×108 cells) (Nature (1993) 362, 255-258; Nature (1987) 326, 292-295), which were cultured in DMEM containing 15% fetal bovine serum, were trypsinized to obtain single isolated cells, washed three times in phosphate buffer, and then prepared as a cell suspension of 1×107 cells/ml. The targeting vector was added to the (25 &mgr;g/l ml cell suspension), and electroporation was performed with a single pulse of 350 V/cm (25 &mgr;F). Then, the ES cells were seeded into 10 cm dishes (1×107 cells/dish), cultured 1 day in maintenance medium, and then the medium was replaced with selection medium (containing G418 (250 &mgr;g/ml) and 2 &mgr;M gancyclovir). The culture was continued with replacing the medium every two days. On the tenth day after transfection, 573 neomycin resistant ES clones were isolated using a micropipet under microscopic observation. The clones were cultured separately in 24 well plates layered with feeder cells, and replica of 573 neomycin resistant ES cells were obtained.

[0282] (3) Screening of Knockout ES Cells

[0283] Each neomycin resistant ES clone was examined by genomic Southern blotting whether its endogenous gene encoding mouse BA0306 protein was inactivated (knocked out) through homologous recombination.

[0284] Genomic DNA was extracted from each neomycin resistant ES clone, and genomic Southern blotting was performed on EcoRI digested genomic DNA fragments according to the standard method using the following probes.

probe 1

[0285] 5′ flanking DNA which was amplified using two primers described in SEQ ID NO: 39 and SEQ ID NO: 40.

probe 2

[0286] 3′ flanking DNA which was amplified using two primers described in SEQ ID NO: 41 and SEQ ID NO: 42. DNA was purified using an automated DNA purification robot (Kubota).

[0287] If the endogenous gene encoding BA0306 is normally targeted by the targeting vector, the 5′ and 3′ flanking genes encompassing the integrated neo gene can be detected as 7 kb and 5 kb bands, respectively.

[0288] The result showed that desired knockout of the gene was occurred in three ES clones (named as 0-16-9, 0-22-11, and 0-22-18), which were used for generation of knockout mice as described below.

[0289] (4) Generation of Knock Out Mice

[0290] The ES clones obtained above, having inactivation in the endogenous gene encoding mouse BA0306 protein as a result of homologous recombination, were microinjected into blastocysts obtained by crossing C57BL6 mice (Japan Charles River) (15 cells/embryo). Immediately after microinjection, the blastocysts were transferred to uterines of ICR mice (Clea Japan) (10 blastocysts/one side of the uterine), which had undergone pseudopregnancy treatment two days and half before. As a result, desired knockout chimera mice were obtained from each ES clone as followings.

[0291] (clone 0-16-9)

[0292] Total number of injected cells: 83

[0293] Littermates: 13

[0294] Chimera mice: 7

[0295] Chimera where contribution to hair color is 80% or more:

[0296] 2

[0297] (clone 0-22-11)

[0298] Total number of injected cells: 202

[0299] Littermates: 12

[0300] Chimera mice: 3

[0301] Chimera where contribution to hair color is 80% or more:

[0302] 3

[0303] (clone 0-22-18)

[0304] Total number of injected cells: 148

[0305] Littermates: 9

[0306] Chimera mice: 5

[0307] The chimera were crossed with normal C57BL6 mice to obtain agouti mice whose color is attributed to a gene determining hair color, originating from ES cells.

Industrial Applicability

[0308] The present invention provides two novel physiologically active protein molecules (BA0306, and BA2303) having characteristics described below, which are specifically expressed in arteriosclerosis or coronary restenosis, and are predicted to relate closely to the onset and progress of these diseases; their fragments; a gene (DNA) encoding the protein molecules; an antibody reactive with the molecule, and its fragment; and pharmaceutical compositions comprising the above protein molecule or the antibody.

[0309] [BA0306]

[0310] A molecule having the following characteristics, and presumed to have inhibitory effects on active oxygen species such as nitrogen monoxide (NO), which has been identified to be involved in the progress of arteriosclerosis and restenosis.

[0311] (1) Its expression is increased from day 1 to day 7 after PTCA of the coronary aorta (peak at day 4).

[0312] (2) Its mRNA is expressed in various human tissues as detected by Northern blotting as approximately 3.5 kb and 4.4 kb bands.

[0313] (3) Its 10 predicted transmembrane regions.

[0314] (4) Its sequence homology at the amino acid level with S. cerevisiae oxidative stress resistance protein, S. cerevisiae zinc/cadmium resistance protein, and heavy metal ion resistance protein, etc.

[0315] [BA2303]

[0316] A molecule having the following characteristics, and presumed to be a G protein(GTP binding protein)-coupled receptor that transduces a specific signal through intracellular G protein to an effector on the plasma membrane or in the cytoplasm by binding to an in vivo ligand which is involved in the onset and progress of arteriosclerosis and restenosis.

[0317] (1) Its expression is increased day 1 after PTCA of the coronary aorta, reaches the maximum on day 2 to day 4, and continued until day 7.

[0318] (2) Its mRNA is expressed in various human tissues as detected by Northern blotting as approximately 3.9 kb and 2.1 kb bands.

[0319] (3) having seven predicted transmembrane regions.

[0320] Therefore, a gene (DNA) or protein of the present invention or its part, and an antibody reactive with the protein, or a part of the antibody are extremely useful in developing the drugs targeting the gene or the protein molecule for treatment and prevention of arteriosclerosis as well as restenosis after PTCA of arterial embolism. Also, the DNA itself is very useful as an antisense medicine, the extracellular domain fragment of the protein is useful as a soluble receptor medicine, and the antibody or its part is useful as an antibody medicine.

[0321] Furthermore, the gene (DNA), protein, and antibody of the present invention are useful as a reagent for screening a protein (ligand) interacting with the protein of the invention, identification of the function of the ligand, and developing a drug which targets the ligand.

[0322] In addition, based on the nucleotide sequence originating from rabbit or mouse, as an embodiment of the DNA of the present invention, model animals (knockout animals) can be generated by disrupting (inactivating) a corresponding endogenous gene. Similarly, trasngenic animals can be generated as a model animal by introducing human DNA, as an embodiment of the DNA of the present invention, into mammals such as mice except human. It is possible to identify the functions of the gene and protein of the invention by analyzing the physical, biological, pathological, and genetical characteristics of the model animals.

[0323] Moreover, it is possible to generate model animals having a human gene of the invention alone by crossing the model animals, whose endogenous gene is disrupted, with the transgenic animals. Thus, it is possible to estimate the therapeutic effects of a drug which targets the introduced human gene (compounds, and antibodies, etc.) by administrating the drug into the model animals.

Claims

1. A DNA encoding a protein having the amino acid sequence of SEQ ID NO: 4.

2. A DNA encoding a protein fragment comprising the extracellular region of a protein having the amino acid sequence of SEQ ID NO: 4.

3. A DNA comprising a nucleotide sequence corresponding to nucleotide residues 97 to 1419 of the nucleotide sequence of SEQ ID NO: 3.

4. A DNA hybridizing with a DNA having the nucleotide sequence of SEQ ID NO: 3 under stringent conditions.

5. A protein having the amino acid sequence of SEQ ID NO: 4 or an amino acid sequence substantially the same as said amino acid sequence.

6. A protein fragment comprising the extracellular region of a protein having the amino acid sequence of SEQ ID NO: 4 or an amino acid sequence substantially the same as said amino acid sequence.

7. A fusion protein between the extracellular region of the protein of claim 5 and the constant region of the heavy chain of human immunoglobulin (Ig) or a portion of the constant region.

8. An expression vector comprising the DNA of any one of claims 1 to 4.

9. A transformant carrying the expression vector of claim 8.

10. An antibody or its portion reactive with the protein of claim 5 or the protein fragment of claim 6.

11. The antibody or its portion of claim 10, wherein the antibody is a monoclonal antibody.

12. A pharmaceutical composition comprising the protein fragment of claim 6 or the fusion protein of claim 7 and a pharmaceutically acceptable carrier.

13. A pharmaceutical composition comprising the antibody or its portion of claim 10 or 11 and a pharmaceutically acceptable carrier.

14. A DNA encoding a protein having the amino acid sequence of SEQ ID NO: 10.

15. A DNA encoding a protein fragment comprising the extracellular region of a protein having the amino acid sequence of SEQ ID NO: 10.

16. A DNA having a nucleotide sequence corresponding to nucleotide residues 1 to 1785 of the nucleotide sequence of SEQ ID NO: 9.

17. A DNA hybridizing with a DNA having the nucleotide sequence of SEQ ID NO: 9 under stringent conditions.

18. A protein having the amino acid sequence of SEQ ID NO: 10 or an amino acid sequence substantially the same as said amino acid sequence.

19. A protein fragment comprising the extracellular region of a protein having the amino acid sequence of SEQ ID NO: 10 or an amino acid sequence substantially the same as said amino acid sequence.

20. A fusion protein comprising the extracellular region of the protein of claim 18 and the constant region of the heavy chain of human immunoglobulin (Ig) or a portion of the constant region.

21. An expression vector comprising the DNA of any one of claims 14 to 17.

22. A transformant carrying the expression vector of claim 21.

23. An antibody or its portion reactive with the protein of claim 18 or the protein fragment of claim 19.

24. The antibody or its portion of claim 23, wherein the antibody is a monoclonal antibody.

25. A pharmaceutical composition comprising the protein fragment of claim 19 or the fusion protein of claim 20 and a pharmaceutically acceptable carrier.

26. A pharmaceutical composition comprising the antibody or its portion of claim 23 or 24 and a pharmaceutically acceptable carrier.

27. A transgenic mouse in which the human-derived DNA comprising a DNA having a nucleotide sequence corresponding to nucleotide residues 97 to 1419 of the nucleotide sequence of SEQ ID NO: 3 is integrated into an endogenous gene of said mouse.

28. A transgenic mouse in which the human-derived DNA comprising a DNA having a nucleotide sequence corresponding to nucleotide residues 1 to 1785 of the nucleotide sequence of SEQ ID NO: 9 is integrated into an endogenous gene of said mouse.

29. A knockout mouse whose endogenous gene encoding a mouse-derived protein having the amino acid sequence of SEQ ID NO: 6 is inactivated so that said protein is not produced.

30. A knockout mouse whose endogenous gene encoding a mouse-derived protein comprising the amino acid sequence of SEQ ID NO: 28 is inactivated so that said protein is not produced.