Patent Application
20090276863
The present invention relates to non-human knockout animals whose S1-5 gene has been made defective and which have developed age-related diseases or symptoms, and methods for producing such animals. The present invention also relates to methods of screening for preventive or therapeutic agents for age-related diseases or symptoms, wherein the methods comprise administering candidate substances to the above-mentioned animals.
Rheumatoid arthritis (hereinafter abbreviated as RA) is a systemic chronic inflammatory disease that shows abnormal proliferation of synovial tissues in the joints. Synovial cells are fibroblast-like cells that form layers one to six of the epithelial-like layers in the synovial membrane in joints, and are thought to provide proteoglycans and hyaluronic acids to the synovial fluid. Synovial tissue proliferates in the joints of RA patients, causing various symptoms to be observed, including multilayered structures and the invasion of inflammatory cells.
While conducting research to elucidate the molecular mechanisms behind the development and progress of RA, the present inventors discovered a novel gene strongly expressed in the synovial tissues of RA patients. The protein encoded by this gene was named synoviolin, after the synovial cells which are the tissues in which the protein is expressed (Patent Document 1).
From biochemical binding experiments on this protein, the present inventors elucidated the presence of S1-5 (also known as EFEMP-1, FBNL, FBLN-3, etc), which is a synoviolin binding factor. S1-5, isolated by the present inventors, is the first protein to be isolated as a synoviolin binding factor.
S1-5 was isolated as a gene overexpressed in human diploid fibroblasts (Lecka-Czernik, B. et al., Molecular and Cellular Biology, 15: 120-128, 1995). In terms of structure, epidermal growth factor (EGF)-like domain and fibrin-like domain, which promote DNA synthesis (cell growth activity) were discovered in S1-5. Further, there are recent reports that S1-5 mutation is related to Malattia Leventinese (ML) and Doyne honeycomb retinal dystrophy (DHRD) (Non-Patent Document 1).
However, the detailed function of S1-5 is unknown, and the phenotype of individuals made S1-5 deficient is not clear.
[Patent Document 1] WO02/052007 pamphlet
An objective of the present invention is to provide non-human knockout animals whose S1-5 gene has been made defective and which develop an age-related disease, and methods for producing such animals. A further objective of the present invention is to provide methods of screening for therapeutic agents and the like for age-related diseases, wherein the methods comprise administering candidate substances to the above-mentioned animals. Another objective of the present invention is to provide cells isolated from the non-human knockout animals, and uses thereof, as well as to provide S1-5 proteins and uses thereof.
Upon dedicated research to achieve the above-mentioned objective, the present inventors discovered that knockout mice whose S1-5 gene function is lost will develop age-related diseases or symptoms. In addition, histological analysis revealed that such knockout mice had decreased bone mineral content, bone mineral density and bone strength; and an increased number of osteoclasts in their bone tissues. In vitro analysis of osteoclast-forming ability using bone marrow cells derived from these knockout mice revealed enhanced osteoclast-forming ability and an increase in osteoclast size compared to using cells derived from wildtype mice. It was also revealed that adding purified S1-5 protein to this in vitro system suppressed osteoclast-forming ability and reduced osteoclast size.
More specifically, the present invention is as follows:
[1] a non-human knockout animal showing an age-related disease or symptom wherein all or a part of the S1-5 gene function is lost;
[2] the animal of [1], wherein the loss of all or a part of the S1-5 gene function is due to a disruption or mutation of the S1-5 gene;
[3] the animal of [1], wherein the age-related disease or symptom is at least one selected from the group consisting of bone deformation, osteoporosis, hair loss, tissue injury or necrosis, tumor, breast hypertrophy, ascites, anemia, bleeding, aging of skin, and aging of nails;
[4] the animal of [1], wherein the animal is selected from the group consisting of zebrafish, mice, rats, guinea pigs, rabbits, chickens, pigs, sheep, goats, dogs, cattle, monkeys, and chimpanzees;
[5] a cell isolated from the non-human knockout animal of any one of [1] to [4];
[6] the cell of [5], which is an osteoclast, keratinocyte epithelial cell, blood cell, cancer cell, bone marrow cell, fibroblast, vascular endothelial cell, dermal cell, muscle cell, nerve cell, osteoblast, lymphocyte, vascular smooth muscle cell, synoviocyte, hair papilla cell, hepatocyte, pigment cell, adipocyte, uterine endothelial cell, or alveolar epithelial cell;
[7] a method for producing a non-human knockout animal that develops an age-related disease, wherein the method comprises causing the loss of all or a part of the S1-5 gene function;
[8] the method of [7], wherein the loss of all or a part of the S1-5 gene function is caused by a disruption or mutation of the S1-5 gene;
[9] the method of [7], wherein the age-related disease or symptom is at least one selected from the group consisting of bone deformation, osteoporosis, hair loss, tissue injury or necrosis, tumor, breast hypertrophy, ascites, anemia, bleeding, aging of skin, and aging of nails;
[10] the method of [7], wherein the animal is selected from the group consisting of zebrafish, mice, rats, guinea pigs, rabbits, chickens, pigs, sheep, goats, dogs, cattle, monkeys, and chimpanzees;
[11] a method of screening for preventive or therapeutic agents for an age-related disease or symptom, wherein the method comprises administering a candidate substance for said preventive or therapeutic agent to the non-human knockout animal of any one of [1] to [4];
[12] a method of screening for preventive or therapeutic agents for an age-related disease or symptom, wherein the method comprises contacting a candidate substance for said preventive or therapeutic agent with cells isolated from the non-human knockout animal of any one of [1] to [4];
[13] the method of [12], wherein the cells are osteoclasts, keratinocyte epithelial cells, blood cells, cancer cells, bone marrow cells, fibroblasts, vascular endothelial cells, dermal cells, muscle cells, nerve cells, osteoblast, lymphocytes, vascular smooth muscle cells, synoviocytes, hair papilla cells, hepatocytes, pigment cells, adipocytes, uterine endothelial cells, or alveolar epithelial cells;
[14] the method of any one of [11] to [13], wherein the age-related disease or symptom is at least one selected from the group consisting of bone deformation, osteoporosis, hair loss, tissue injury or necrosis, tumor, breast hypertrophy, ascites, anemia, bleeding, aging of skin, and aging of nails;
[15] a method of screening for agents that inhibit osteoclast function, wherein the method comprises contacting a candidate substance for said agent that inhibits osteoclast function with osteoclasts derived from the non-human knockout animal of any one of [1] to [4];
[16] an isolated protein, which is any one of (a) to (d):
(a) a protein comprising the amino acid sequence of SEQ ID NO: 2 or 4;
(b) a protein encoded by a DNA comprising a coding region of the nucleotide sequence of SEQ ID NO: 1 or 3;
(c) a protein comprising an amino acid sequence with one or more amino acid substitutions, deletions, insertions, and/or additions in the amino acid sequence of SEQ ID NO: 2 or 4, wherein the protein is functionally equivalent to a protein comprising the amino acid sequence of SEQ ID NO: 2 or 4; and
(d) a protein encoded by a DNA that hybridizes under stringent conditions with a DNA comprising the nucleotide sequence of SEQ ID NO: 1 or 3, wherein the protein is functionally equivalent to a protein comprising the amino acid sequence of SEQ ID NO: 2 or 4.
[17] a partial peptide of the protein of [16];
[18] the peptide of [17], which comprises the amino acid sequence of SEQ ID NO: 6;
[19] a preventive or therapeutic agent for an age-related disease or symptom, wherein the agent comprises the protein of [16], or the peptide of [17] or [18];
[20] the preventive or therapeutic agent of [19], wherein the age-related disease or symptom is at least one selected from the group consisting of bone deformation, osteoporosis, hair loss, tissue injury or necrosis, tumor, breast hypertrophy, ascites, anemia, bleeding, aging of skin, and aging of nails;
[21] an agent that inhibits osteoclast function, wherein the agent comprises the protein of [16], or the peptide of [17] or [18]; and
[22] an antibody that binds to the protein of [16], or to the peptide of [17] or [18].
The present invention provides knockout animals in which the S1-5 gene has been made defective, where these animals develop age-related diseases, and also provides methods for producing such animals. Since the animals of the present invention develop various age-related diseases and symptoms, such as bone deformation, hair loss, tissue injury and tumor development, they may be used as model animals to screen for pharmaceutical compositions with therapeutic or remedial effects by administering substances effective for the treatment or prevention of age-related diseases to these animals. The present invention also provides cells isolated from the knockout animals. The use of these cells enables screening for pharmaceutical agents for the treatment or prevention of age-related diseases. Since the bone marrow cells isolated from the knockout animals have a greater ability to form TRAP-positive multinucleated giant cells when differentiated into osteoclasts than the bone marrow cells of wild type mice, agents that inhibit osteoclast function can be screened by using the number and/or size of TRAP-positive multinucleated giant cells as an indicator.
The present invention also provides isolated S1-5 protein and antibodies that bind to the S1-5 protein. The use of the isolated S1-5 protein enables treatment or prevention of age-related diseases and inhibition of osteoclast activity.
Hereinafter, the present invention will be specifically described.
The gene encoding S1-5 is publicly known; the S1-5 protein specified by accession number AAA65590 (nucleotide accession U03877), 138449, NP—061489 (nucleotide accession NM 018894), NP—004096 (nucleotide accession NM 004105), or Q12805 and similar proteins comprising the activity of binding to human synoviolin protein may also be used (Lecka-Czernik, B. et al, Mol. Cell. Biol. 15: 120-128, 1995; Heon, E. et al., Arch. Opthalmol. 114: 193-198, 1996; Ikegawa, S. et al, Genomics 35: 590-592, 1996; Katsanis, N. et al., Hum. Genet. 106: 66-72, 2000; Giltay, R. et al., Matrix. Biol. 18: 469-480, 1999; Stone, E. M. et al., Nat. Genet.22: 199-202, 1999).
S1-5 gene can be obtained from a genomic library of mice, rats, or such. For example, desired clones can be obtained from a bacterial artificial chromosome (BAC) library by using hybridization methods. Such clones may also be obtained using PCR methods.
The present invention provides 1) non-human knockout animals that have developed an age-related disease or symptom, in which all or a part of S1-5 gene function has been lost, and 2) methods for producing non-human knockout animals that develop an age-related disease, wherein the methods comprise causing the loss of all or a part of S1-5 gene function. The loss of all or a part of S1-5 gene function may be effected by, for example, disrupting or mutating the S1-5 gene.
In the present invention, gene targeting may be used to generate knockout animals in which all or a part of S1-5 function is lost.
An S1-5 gene targeting vector is used to cause the loss of all or a part of S1-5 gene function by disrupting the S1-5 gene. Herein, the phrase “to cause the loss of a function” means to completely lose gene function, or to produce a condition whereby gene function is reduced compared to the wildtype.
A function can be lost simply by disrupting or deleting a gene, or by making a modification, such as introducing a mutation into the gene such that a frame shift will occur during translation.
The “knockout animals” of the present invention can be produced as follows:
First, an S1-5 gene in which all or a part of the nucleotide sequence has been modified is introduced into totipotent cells, and those totipotent cells transfected with the modified S1-5 gene are then selected. Next, the selected genetically modified (deleted, disrupted, mutated, etc.) totipotent cells are introduced into fertilized eggs to produce chimeric individuals. Crossing the obtained chimeric individuals will produce individuals in which one or both S1-5 genes on homologous chromosomes have been knocked out.
The types of animals used in the present invention are not particularly limited. For example, with the exception of humans, the animals include zebrafish, mice, rats, guinea pigs, rabbits, chickens, pigs, sheep, goats, dogs, cattle, monkeys, and chimpanzees. Mice are preferred in the present invention since they are easy to handle and reproduce readily.
Herein, a part or all of the nucleotide sequence of the S1-5 gene can be modified to cause the loss of S1-5 gene function. The term “modify” means to introduce a mutation that causes a deletion, substitution, or addition to a part of the DNA of the S1-5 gene. Such mutations include the use of genetic engineering techniques to delete a part or all of the nucleotide sequence, or to insert another gene or nucleotide sequence, or to substitute a gene or nucleotide sequence. For example, a defective S1-5 gene can be produced by shifting a codon reading frame, or by disrupting the function of a promoter or exon. As a result, the S1-5 protein produced by expressing the S1-5 gene will not function.
The knockout mice of the present invention can be produced by known methods for gene recombination (gene targeting). Gene targeting is a technique well known in the art, and is disclosed in various laboratory manuals in the present field.
When designing a targeting vector, the part that causes the change in S1-5 gene structure is not particularly limited, so long as the function of the S1-5 gene is lost. However, considering the function and structure of the S1-5 gene, vectors designed such that a region of the EGF-like domain or fibrin-like domain of the S1-5 gene is deleted are particularly preferable.
Recombinants carrying the vector are preferably selected by the combined use of screening using a drug-resistance gene introduced by the targeting vector, and screening using Southern blotting or PCR. Neomycin resistance gene, hygromycin B phosphotransferase gene, or such may be used as drug selection marker genes. HSV thymidine kinase gene, diphtheria toxin A gene, or such may be used as genes for negative selection.
Homologous recombination is performed using a targeting vector produced by an above-described method. As used herein, “homologous recombination” means that a modified S1-5 gene is artificially recombined into a DNA region of the S1-5 gene in a genome.
To obtain a desired recombinant, a large number of recombinants must be screened. However, screening a large number of fertilized eggs is technically difficult. Therefore, it is preferable to use cells that can be cultured in vitro and are multipotent, like fertilized eggs. Embryonic stem (ES) cells and such have been established as totipotent cells for mice (Nature 292:154-156, 1981), rats (Iannaccone, P. M. et al., Dev. Biol. 163(1): 288-292, 1994), monkeys (Thomson, J. A. et al., Proc. Natl. Acad. Sci. U.S.A. 92(17):7844-7848, 1995) and rabbits (Schoonjans, L. et al., Mol. Reprod. Dev. 45(4):439-443, 1996). For pigs, embryonic germ (EG) cells have been established (Shim H. et al., Biol. Reprod 57(5):1089-1095, 1997).
Therefore, in the present invention, knockout animals are preferably produced using these animal species. Mice, for which techniques relating to the production of knockout animals are well established, are particularly suitable. With regards to mouse ES cells, several ES cell lines derived from mice are currently established, and for example, TT-2 cell line, AB-1 cell line, J1 cell line, or R1 cell line may be used. A selection regarding which of these ES cell lines to use can be appropriately made according to the objectives or methods of the experiment.
When establishing ES cells, blastocysts 3.5 days after fertilization are generally used. As an alternative to this, embryos in the eight-cell stage can be collected and the blastocysts produced by culturing these embryos can be used to efficiently obtain many early stage embryos.
ES cell lines obtained this way are usually very proliferative; however, since they easily lose the regenerative capacity that enables ontogenesis, they must be subcultured carefully. For example, the methods employed involve culturing cells on appropriate feeder cells, such as STO fibroblasts, in the presence of leukemia inhibitory factor (LIF) (1 to 10000 U/ml) in a carbon dioxide incubator (preferably 5% carbon dioxide gas and 95% air; or 5% oxygen, 5% carbon dioxide gas, and 90% air) at approximately 37° C., and subculturing, for example, by separating into single cells with trypsin/EDTA solution treatment, and then plating onto freshly prepared feeder cells. Such subculturing is ordinarily carried out every one to three days, and cell morphology is preferably observed.
Genes can be transfected into ES cells using methods such as calcium phosphate coprecipitation, electroporation, lipofection, retroviral infection, agglutination, microinjection, and particle guns, but electroporation is preferred since many cells can be treated with ease.
The resultant recombinant ES cells are screened to check whether homologous recombination has taken place. More specifically, the cells are first screened using a drug resistance factor introduced with neomycin or such. Examples of drug resistance genes include neomycin phosphotransferase II (npt II) gene and hygromycin phosphotransferase (hpt) gene. Examples of reporter genes include β-galactosidase (lacZ) gene and chloramphenicol acetyltransferase (cat) gene.
Additionally, the obtained recombinant ES cells can be reliably screened to determine whether homologous recombination has taken place by performing Southern hybridization analysis using a DNA sequence on the S1-5 gene or in its vicinity as a probe; or by performing PCR using as primers a DNA sequence on the targeting vector and the DNA sequence of a region near but not within the mouse-derived S1-5 gene used for the targeting vector.
These assays enable the selection of cells in which correct homologous recombination has taken place between the wildtype S1-5 gene located on the chromosome and the introduced S1-5 gene fragment, such that the mutation is transferred to the S1-5 gene on the chromosome.
Those ES cells in which the incorporation of the transgene has been confirmed are returned to embryos derived from the same type of non-human mammal, thus enabling the incorporation of the cells into the cell mass of the host embryo, and chimeric embryos are formed. Known methods for introducing ES cells into embryos such as blastocysts include microinjection and agglutination. However, any method may be used, and those skilled in the art may appropriately modify these methods.
When using mice, female mice subjected to superovulation treatment using hormone agents (using, for example, pregnant mare's serum gonadotropin (PMSG), which has a follicle stimulating hormone (FSH)-like action, and human chorionic gonadotrophin (hCG), which has a luteinizing hormone (LH) action) are mated with male mice. Thereafter, embryos in the early stage of development are collected from the uterus 3.5 days after fertilization when using blastocysts, and 2.5 days after fertilization when using eight-cell stage embryos. ES cells that are homologously recombined using a targeting vector are injected in vitro into embryos collected in this manner, producing chimeric embryos. Alternatively, the zona pellucida of two-day-old mice embryos (eight-cell stage embryos) is removed and cultured with ES cells to produce an aggregate. Blastocysts are produced by cultivating this aggregate for one day, and the blastocysts are then transplanted into foster mothers, developed, and grown to produce chimeric mice. Pseudopregnant female mice for use as foster mothers can be obtained by mating female mice with a normal estrous cycle with male mice castrated by vasoligation, or such. Chimeric mice can then be produced by transplanting chimeric embryos produced by a method described above into the uterus of the pseudopregnant mice thus produced, and then causing pregnancy and delivery. To increase the certainty that implantation of the chimeric embryos and pregnancy will take place, the female mice from which the fertilized eggs are collected and the pseudopregnant mice that become the foster mothers are preferably produced from a group of female mice with the same estrous cycle.
Then, chimeric mice are selected from those babies born to the foster mothers. If individual mice derived from the ES cell-transplanted embryos are obtained, they are crossed with wildtype mice to confirm whether or not the phenotype derived from the ES cell appears in second generation individuals. If the phenotype derived from the ES cell does appear in second generation individuals, one may assume that the ES cell was introduced into the germline of the chimeric mouse. Various phenotypes can be used as indicators to verify that the ES cell was introduced into the germline; however, for ease of verification, hair color is preferably used as an indicator. Known hair colors for mice include agouti, black, ocher, chocolate, and white. It is also possible to make selections by extracting chromosomal DNA from a part of a body (for example from the tail tip) and then performing Southern blotting or PCR assays. It is very likely the ES cell has been introduced into the germline of chimeric mice whose chimeric contribution is high. As described above, a chimeric mouse is selected and then crossed with a wildtype male to obtain F1 individuals and then to establish a mutant mouse strain.
A chimeric animal obtained as described above is a heterozygote with a genetic defect in only one of its homologous chromosomes. F1 heterozygotes comprising a genetic defect in only one of their homologous chromosomes can be crossed with each other to obtain a homozygous knockout animal in which both S1-5 genes on homologous chromosomes are defective.
Whether or not the obtained animal is a knockout animal is verified by extracting chromosomal DNAs from its tissues and then performing Southern hybridization analysis or PCR on the animal. Also, abnormalities in the tissues and organs can be observed at autopsy. In addition, RNA can be extracted from the tissues, and the gene expression pattern can be analyzed using Northern blot analysis. Blood can also be collected as necessary to carry out blood tests and serum biochemical tests.
Homozygous knockout animals produced at this point may suffer fetal death or such, or may not develop in to adults, making them inappropriate as model animals. In such cases, the gene is preferably knocked out at a required time. Further, to investigate the function of a gene in a specific tissue in vivo, the gene is preferably knocked out tissue-specifically. Such animals in which a gene is knocked out at a specific time or only from a specific cell line, and animals in which a gene is knocked out only in a limited region of somatic cells are called conditional knockout animals (Bio Manual Series 8, Gene Targeting: Production of mutant mice using ES cells, Aizawa, S., Yodosha, 1995).
The Cre-loxP system (R. Kuhn. et al., Science 269: 1427-1429, 1995), which is a recombination system derived from bacteriophage P1 for gene targeting, can be used as a method for producing conditional knockout animals. Cre is a recombinase and recognizes a 34-bp sequence called loxP, which allows recombination to take place at this site. Therefore, by placing a gene to be targeted between two loxP sequences, and inserting the Cre recombinase gene downstream of a specific promoter, Cre can be produced at a specific site and at a specific time, and the gene between the loxPs can be cut out (i.e. the function of a desired gene can be obliterated at a particular site and time). When designing a targeting vector using the Cre-loxP system in the present invention, the part that changes the structure of the S1-5 gene is not particularly limited, so long as the function of the S1-5 gene is lost. Considering the function and structure of the S1-5 gene, it is particularly preferable to design a targeting vector such that a region of the EGF-like domain or fibrin-like domain of the S1-5 gene is deleted.
3. Cells Isolated from the Non-Human Knockout Animals
The present invention also provides cells isolated from the knockout animals of the present invention. As described below, cells isolated from the knockout animals of the present invention can be used to screen for preventive or therapeutic agents for age-related diseases or symptoms.
Examples of such cells include, but are not limited to osteoclasts, keratinocyte epithelial cells, blood cells, cancer cells, bone marrow cells, fibroblasts, vascular endothelial cells, dermal cells, muscle cells, nerve cells, osteoblasts, lymphocytes, vascular smooth muscle cells, synoviocytes, hair papilla cells, hepatocytes, pigment cells, adipocytes, uterine endothelial cells, or alveolar epithelial cells.
These cells can be isolated from the knockout animals by methods well known to those skilled in the art.
The non-human knockout animals of the present invention show an age-related disease or symptom. Known mouse models of senescence are Klotho mutant mice (Kuro-o, M. et al., Nature, 6; 390(6655): 18-19, 1997), senescence accelerated model mice (SAM) (Takeda, T. et al., Mech. Ageing Dev., 17 (2), 183-194, 1981), and Werner's syndrome model mice (Chen, L. et al., J. Biomed. Biotechnol., 2 (2), 46-54, 2002); these mice demonstrate early senescence and are short lived. A characteristic of the non-human knockout animals of the present invention (for example, S1-5 knockout mouse) is that their lifespan is not different from that of wildtype mice, but that they have a variety of age-related diseases or symptoms that develop into serious conditions. In the present invention, the phrase “age-related disease or symptom” refers to, for example, bone deformation, osteoporosis, hair loss, tissue injury or necrosis, tumor, breast hypertrophy, ascites, anemia, bleeding, aging of skin (including blotches, dullness of skin, flabby skin, fine wrinkles, moles, and so on), and aging of nails, and means that such diseases or symptoms appear individually or in combination. “Bone deformation” means that the strength of the osteocartilage is decreased due to aging, RA, or osteoporosis, and that the bones and cartilage are deformed. “Osteoporosis” refers to a condition in which the osseous components generally decrease, and fracture is likely to occur. More than 90% of osteoporosis is primary osteoporosis, for which an obvious causative disease is not found, and most of it is involutional osteoporosis that develops in middle-aged and elderly people. Development of secondary osteoporosis, which differs from the above, is caused by Basedow's disease, Cushing's syndrome, severe diabetes, RA, stomach surgery, alcohol polydipsia, use of steroidal agents, or such.
“Tumor” means all tumorigenic cell growth and proliferation, and all precancerous and cancerous cells and tissues, regardless of whether they are malignant or benign. The tumors of the present invention may be primary tumors or metastatic tumors. The terms “cancer” and “cancerous” typically refer to a physiological condition characterized by cell growth that has become uncontrollable. In the present invention, examples of “tumors” include carcinomas, sarcomas, leukemias, and malignant lymphomas. In the present invention, examples of carcinomas include breast cancer, prostate cancer, colon cancer, squamous cell carcinoma, small cell lung cancer, non-small-cell lung cancer, gastrointestinal cancer, pancreatic cancer, glioblastoma, uterine cervical cancer, ovarian cancer, liver cancer, bladder cancer, hepatoma, colorectal cancer, endometrial cancer, salivary gland cancer, renal cancer, vulva cancer, thyroid cancer, hepatic cancer, and various types of cancers of the head and neck. In the present invention, examples of sarcomas include malignant osteoma, and malignant soft tissue sarcoma, or more specifically, osteosarcoma, chondrosarcoma, Ewing's sarcoma, liposarcoma, leiomyosarcoma, or synovial sarcoma
The present invention provides methods of screening for therapeutic or preventive agents for age-related diseases or symptoms, in which the methods comprise administering a candidate substance to a non-human knockout animal.
In these screening methods, substances with the activity of complementing the phenotype of a knockout animal are selected from among the candidate substances for preventive or therapeutic agents for age-related diseases or symptoms. Complementing the phenotype of the knockout animal includes not only complete but also incomplete complementation.
More specifically, a candidate substance is contacted with a knockout animal of the present invention or a part thereof, and an indicator value correlated with the targeted disease is measured in the non-human animal or the part thereof that was contacted with the candidate substance. The value is compared with that of a control, and based on this comparison, the effect of the candidate substance on the desired age-related disease is evaluated. Preventive, therapeutic, and remedial effects of the candidate substance can be tested using an increase in bone mineral density, anti-tumor effect, increase of blood cells, improved hemostatic ability, suppression of osteoclast activity, or such as the indicator. Tests can also be carried out on animals that show aging of skin (blotches, dullness of skin, flabby skin, fine wrinkles, moles, etc.) to screen for cosmetics that yield whitening and anti-aging effects.
A “knockout animal or a part thereof” includes both the animal's entire body and specific tissues or organs. Specific tissues or organs also include those removed from the animal.
Candidate substances may be, for example, peptides, proteins, non-peptide compounds, synthetic compounds, fermentation products, cell extracts, plant extracts, animal tissue extracts, plasmas, and such, and these compounds may be novel compounds or publicly known compounds. Such candidate substances may form salts, and salts of the candidate substances that are used include physiologically acceptable acids (such as inorganic acids) and bases (such as organic acids), and in particular, physiologically acceptable acid addition salts are preferred. Examples of such salts include salts formed with inorganic acids (for example, hydrochloric acid, phosphoric acid, hydrobromic acid, and sulfuric acid), or salts formed with organic acids (for example, acetic acid, formic acid, propionic acid, fumaric acid, maleic acid, succinic acid, tartaric acid, citric acid, malic acid, oxalic acid, benzoic acid, methanesulfonic acid, and benzenesulfonic acid).
The methods that may be used for treating test animals with candidate substances include oral administration, intravenous injection, swabbing, subcutaneous administration, intradermal administration, and peritoneal administration, and can be selected appropriately depending on the symptoms of the test animals, properties of the candidate substance, and such. The dose of a candidate substance can be selected appropriately according to the method of administration, properties of the candidate substance, and such.
For example, when screening for preventive, therapeutic, or remedial agents for osteoporosis, effective substances can be screened by administering a candidate substance to a knockout animal of the present invention, and then measuring bone mineral density, X-ray photographs, changes in the body weight and so on of the animal over time. In particular, since osteoporosis and spinalkyphosis are correlated in the knockout mice, the present invention revealed that the degree of kyphosis in the knockout animal may be an indicator for measuring the progress of osteoporosis. Therefore, the efficacy of a candidate substance on osteoporosis can be determined non-invasively and efficiently by administering a candidate substance to a knockout animal of the present invention, and using X-ray photographs and such to determine the degree of kyphosis in the animal over time.
Cells isolated from the knockout animals of the present invention can be used to screen for preventive or therapeutic agents for age-related diseases or symptoms. More specifically, the present invention provides methods of screening for preventive or therapeutic agents for age-related diseases or symptoms, in which the methods comprise a step of contacting a candidate substance for the preventive or therapeutic agent with a cell isolated from a knockout animal of the present invention.
In the present invention “contact” can be carried out, for example, by adding a candidate substance to a culture medium of cells isolated from a knockout animal of the present invention. For example, if the candidate substance is a protein, “contact” can be carried out by transfecting cells isolated from the knockout animal with a vector comprising a DNA encoding this protein.
In the present invention, a substance with the activity of complementing the phenotype of a cell isolated from a knockout animal is selected from among candidate substances for preventive or therapeutic agents for age-related diseases or symptoms. Without particular limitation, the phenotype of a cell isolated from a knockout animal includes, for example, the activity of suppressing osteoclast activity for osteoclasts, suppressing osteoclast formation for bone marrow cells, keratinocyte epithelial cell growth for epithelial cells, promoting blood cell differentiation for blood cells, suppressing cancer cell growth for cancer cells, fibroblast growth for fibroblasts, vascular endothelial cell growth for vascular endothelial cells, hair formation for dermal cells, correcting muscle cell degeneration for muscle cells, correcting nerve cell degeneration for nerve cells, accelerating osteoblast growth and differentiation for osteoblasts, suppressing lymphocyte activation for lymphocytes, inhibiting growth for vascular smooth muscle cells, normalizing function for synoviocytes, hair growth for hair papilla cells, normalizing function for hepatocytes, suppressing melanin production for pigment cells, correcting activation abnormality for alveolar cells, suppressing differentiation and proliferation for adipocytes, and inhibiting endothelial cell growth for uterine endothelial cells. Complementing cell phenotype includes not only complete but also incomplete complementation.
6. Screening for Agents that Inhibit Osteoclast Function
The present invention also provides methods of screening for agents that inhibit osteoclast function, wherein the methods comprise a step of contacting a candidate substance for an agent that inhibits osteoclast function with osteoclasts isolated from a knockout animal. Examples of “osteoclast function” include, but are not limited to resorption lacunae formation (resorption lacunae-forming activity) and suppression of the formation of tartrate resistant acid phosphatase (TRAP)-positive cells (TRAP-positive cell formation-suppressing activity), but as long as the function directly or indirectly leads to bone destruction, it is included in “osteoclast function”.
Agents that inhibit osteoclast function can be screened by, for example, using as an indicator the formed number, size, and TRAP activity of osteoclasts isolated from a knockout animal of the present invention. However, the screening is not limited to these methods, and for example, as indicated in the Examples, screening can be carried out by differentiating bone marrow cells isolated from a knockout animal of the present invention into multinucleated giant cells, and then using as indicators the number, size and so on of TRAP-positive multinucleated giant cells (Takahashi N. et al., Endocrinology, 123(5):2600-2, 1988; Yasuda H. et al., Proc. Natl. Acad. Sci. USA, 31; 95(7), 3597-602, 1998).
Agents that inhibit osteoclast function can be screened by using the activity of forming resorption lacunae as an indicator in the pit assay system (Hirayama, T. et al., J. Endocrinol.: October 175(1):155-63 2002; Udagawa, N. et al., Bone.: November; 25(5):517-23 1999).
Substances inhibiting osteoclast activity selected by this screening method can be used in the fields of research and medicine as agents that inhibit osteoclast function. The agents that inhibit osteoclast activity of the present invention may find application as preventive or therapeutic agents for age-related diseases or symptoms.
When the forefront of a proliferated synovial membrane invading into the bone is examined pathologically at the site of osteolysis in RA patients, many multinucleated giant cells are found. Such cells are TRAP positive; that is, they are known to fit the phenotype of osteoclasts, and osteoclasts presumably have an important role in osteolysis in RA (Arthritis Rheum. March; 50(3):794-804, 2004; Biochem. Biophys. Res. Commun. November 17; 240(2):279-86, 1997). Therefore, the agents that inhibit osteoclast function of the present invention can be used as preventive or therapeutic agents of RA.
The present invention provides 1) isolated S1-5 protein encoded by a DNA comprising the coding region of the nucleotide sequence of SEQ ID NO: 1 or 3; and 2) isolated S1-5 protein comprising the amino acid sequence of SEQ ID NO: 2 or 4. Herein, “isolated” refers to a condition of being taken out of the natural environment.
The above-mentioned proteins can be prepared, for example, as recombinants. For example, in the case of human S1-5 protein, a cDNA library is obtained based on mRNAs extracted from cells that express human S1-5 protein (for example, human diploid fibroblasts, and RA patient-derived synovial cells collected as synovial tissues or cultured cells) (Short, J. M. et al., Nucleic Acid Research, 16, 7583, 1988). DNAs that encode the S1-5 protein can be isolated by screening this library for hybridizing clones using a probe designed on the basis of the nucleotide sequence of SEQ ID NO: 1. S1-5 protein encoded by this DNA can be obtained using a protein expression system well known to those skilled in the art. Human S1-5 protein can be collected and purified from cultures of cells that express the human S1-5 protein.
The present invention also provides proteins that are functionally equivalent to the above-mentioned S1-5 protein. The biological species from which such proteins are derived include, without limitation, humans, zebrafish, mice, rats, guinea pigs, rabbits, chickens, pigs, sheep, goats, dogs, cattle, monkeys, and chimpanzees.
Proteins functionally equivalent to the S1-5 protein include 1) isolated proteins comprising an amino acid sequence with one or more amino acid substitutions, deletions, insertions, and/or additions in the amino acid sequence of SEQ ID NO: 2 or 4, wherein the protein is functionally equivalent to a protein comprising the amino acid sequence of SEQ ID NO: 2 or 4; and 2) isolated proteins encoded by a DNA that hybridizes under stringent conditions with a DNA comprising the nucleotide sequence of SEQ ID NO: 1 or 3, wherein the protein is functionally equivalent to a protein comprising the amino acid sequence of SEQ ID NO: 2 or 4.
The proteins functionally equivalent to the S1-5 protein include proteins having the function of suppressing age-related diseases or symptoms of humans, and proteins having the function of complementing the phenotype of the knockout animals of the present invention or the cells isolated therefrom.
Proteins functionally equivalent to S1-5 protein may include proteins that are immunologically equivalent. In the present invention, “proteins that are immunologically equivalent to S1-5 protein” are not particularly limited, so long as the proteins react with antibodies that specifically recognize S1-5 protein. Examples of proteins immunologically equivalent to S1-5 protein include epitope peptides of the S1-5 protein, domains of the S1-5 protein comprising these epitopes, or proteins comprising these domains.
S1-5 protein fragments can be obtained by digestion using proteases. Alternatively, they can be obtained by randomly digesting DNAs encoding the S1-5 protein, which is shown in SEQ ID NO: 1 or 3, and then inserting these fragments into phage vectors to produce phage libraries that display domain peptides. Immunologically active domains can be determined by immunoscreening these phage libraries using antibodies that recognize S1-5 protein. The amino acid sequence of an active domain can be elucidated by sequencing the insert of the cloned phage.
The proteins functionally equivalent to S1-5 protein of the present invention are defined not only in terms of immunological characteristics, but also in terms of binding characteristics with synoviolin. More specifically, the present invention comprises S1-5 protein fragments with affinity towards synoviolin. Those skilled in the art can readily select such mutants by using synoviolin to screen candidate proteins. For example, the S1-5 protein requires 120 amino acid residues, corresponding to positions 1233-1592 in the cDNA of synoviolin, as a region necessary for binding with synoviolin. Therefore, proteins that bind to a protein consisting of an amino acid sequence that constitutes this region, or to a protein that comprises this amino acid sequence constitute the proteins functionally equivalent to S1-5 protein of the present invention.
In addition, the proteins functionally equivalent to S1-5 protein of the present invention are also defined in terms of the biochemical activity possessed by the S1-5 protein. Examples of S1-5 protein biochemical activities include the activity of inhibiting osteoclast formation, and the activity of regulating cell growth (Lecka-Czernik, B., Mol. Cell. Biol. 15: 120-128, 1995).
These proteins functionally equivalent to S1-5 protein can be made into fusion proteins with other proteins. For example, the functionally equivalent proteins include proteins that maintain at least one characteristic of a protein functionally equivalent to S1-5 protein and to which an additional amino acid sequence, such as FLAG tag, HA tag, and histidine tag, has been added. Even if the protein to be added to comprises activity different from that of S1-5 protein, if the fusion protein maintains at least one of the functions of the S1-5 protein, that fusion protein is included in the functionally equivalent proteins of the present invention.
Proteins functionally equivalent to the S1-5 protein can be isolated by methods well known to those skilled in the art (Experimental Medicine Supplementary Volume: Genetic Engineering Handbook, pp. 246-251, Yodosha, 1991). For example by screening a desired library using the nucleotide sequence of SEQ ID NO: 1 or 3 (or a fragment thereof) as a probe, DNAs with a highly homologous nucleotide sequence can be cloned. Examples of such libraries include libraries in which random mutations have been introduced to the nucleotide sequence of SEQ ID NO: 1 or 3, and cDNA libraries of synovial tissues derived from human or non-human species.
Known methods for introducing random mutations to a given nucleotide sequence include substitution of base pairs by nitrous acid treatment of DNA (Hirose, S. et al., Proc. Natl. Acad. Sci. USA. 79: 7258-7260, 1982). In this method, base pair substitutions can be introduced randomly into a specific segment in which mutations are desired by performing nitrous acid treatment on that segment. Alternatively, an example of a technique for introducing a desired mutation at a discretionary site is the gapped duplex method (Kramer, W. and Fritz H J., Methods in Enzymol. 154: 350-367, 1987). The gene that should incorporate the mutation is cloned into a cyclic double-stranded vector, and this vector is separated into single strands and then hybridized with a synthetic oligonucleotide that carries a mutation at a desired site. A complementary single-stranded DNA derived from a vector linearized by restriction enzyme cleavage is annealed to the cyclic single-stranded vector, the gap between the synthetic nucleotide is filled using DNA polymerase, and then further ligation gives a complete double-stranded cyclic vector.
The number of modified amino acids may be typically 50 amino acids or less, preferably 30 amino acids or less, and more preferably five amino acids or less (for example, one amino acid).
When artificially substituting an amino acid, substitution using an amino acid with similar properties should facilitate maintenance of the activity of the original protein. The proteins of the present invention include proteins in which the above-mentioned amino acid substitution was a conservative substitution, where the proteins are functionally equivalent to human S1-5 protein (SEQ ID NO: 2 or 4). Conservative substitution is considered important when substituting amino acids of domains important for protein activity. This kind of conservative amino acid substitution is well known to those skilled in the art.
Groups of amino acids suited to conservative substitution are, for example, basic amino acids (such as lysine, arginine and histidine), acidic amino acids (such as aspartic acid and glutamic acid), uncharged polar amino acids (such as glycine, asparagine, glutamine, serine, threonine, tyrosine and cysteine), non-polar amino acids (such as alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine and tryptophan), β-branched amino acids (such as threonine, valine and isoleucine), and aromatic amino acids (such as tyrosine, phenylalanine, tryptophan and histidine).
The activity of a protein may be increased (including, for example, constitutively activated proteins) or decreased (including, for example, dominant negative proteins) by non-conservative substitution.
Proteins comprising an amino acid sequence with one or more amino acid substitutions, deletions, insertions, and/or additions in the amino acid sequence of SEQ ID NO: 2 or 4, wherein the proteins are functionally equivalent to a protein comprising the amino acid sequence of SEQ ID NO: 2 or 4, include naturally existing proteins. In general, eukaryote genes show polymorphisms, as seen in interferon genes and such. There are cases where differences in nucleotide sequence due to this polymorphism may cause substitution, deletion, insertion and/or addition of one or more amino acids. Therefore, naturally existing proteins comprising an amino acid sequence with one or more amino acid substitutions, deletions, insertions, and/or additions in the amino acid sequence of SEQ ID NO: 2 or 4, wherein the proteins are functionally equivalent to a protein comprising the amino acid sequence of SEQ ID NO: 2 or 4, are included in the present invention.
Alternatively, in some cases polymorphism can cause a change in the nucleotide sequence, but the amino acid sequence does not change. Such nucleotide sequence mutations are called silent mutations. Proteins encoded by DNAs comprising a nucleotide sequence with silent mutations are also included in the present invention. Herein, polymorphism means that the nucleotide sequence of a certain gene differs between individuals within a group. Polymorphism is unrelated to the proportion of different genes found.
In addition, hybridization can be included as an example of a method that can be used to obtain proteins functionally equivalent to S1-5 protein. More specifically, DNAs which encode an S1-5 protein of the present invention, and which are shown in SEQ ID NO: 1 or 3, or fragments thereof, are used as probes to isolate DNAs that hybridize with the probes. When hybridization is carried out under stringent conditions, DNAs with highly homologous nucleotide sequences will be selected, and as a result, there will be an increased possibility that the isolated proteins will comprise proteins functionally equivalent to S1-5 protein. For example, highly homologous nucleotide sequences refer to sequences with identity of 70% or more, and preferably 90% or more.
Stringent conditions specifically refer to, for example, hybridization in 6×SSC and 40% formamide at 25° C., and then washing with 1×SSC at 55° C. Stringency is influenced by conditions such as salt concentration, formamide concentration, and temperature, but those skilled in the art can obviously set these conditions to yield necessary stringencies.
The use of hybridization enables isolation of, for example, a DNA encoding a homolog of the S1-5 protein in a non-human animal species. Homologs of the S1-5 protein encoded by DNAs obtainable from non-human animal species, or more specifically, from zebrafish, mice, rats, guinea pigs, rabbits, chickens, pigs, sheep, goats, dogs, cattle, monkeys, chimpanzees, and such, constitute the functionally equivalent proteins of the present invention.
Proteins obtained by introducing a mutation into the S1-5 protein (SEQ ID NO: 2 or 4), or proteins encoded by a DNA isolated using a hybridization technique and such ordinarily share high homology in the amino acid sequences with that of S1-5 protein (SEQ ID NO: 2 or 4). High homology refers to sequence identity of at least 30% or more, preferably 50% or more, and even more preferably 80% or more (for example, 95% or more). The identity of nucleotide sequences or amino acid sequences can be determined on the internet using a homology search site. [For example, homology searches such as FASTA, BLAST, PSI-BLAST, and SSEARCH can be used through the DNA Data Bank of Japan (DDBJ) [for example, the Search and Analysis page on the website of DNA Data Bank of Japan; http://www.ddbj.nig.acjp/E-mail/homology-j.htmm]. Searches using BLAST can be performed through the National Center for Biotechnology Information (NCBI) (for example, the BLAST page on the NCBI homepage; http://www.ncbi.nlm.nih.gov/BLAST/; Altschul, S. F. et al., J. Mol. Biol. 215(3): 403-10, 1990; Altschul, S. F. & Gish, W., Meth. Enzymol. 266:460-480, 1996; Altschul, S. F. et al., Nucleic Acids. Res. 25: 3389-3402, 1997)].
For example, when calculating amino acid sequence identity using Advanced BLAST 2.1, a search is carried out using blastp as the program, setting the Expect value to 10, setting all filters to OFF, using BLOSUM62 as the Matrix, and setting the Gap existence cost, Per residue gap cost, and Lambda ratio to 11, 1, and 0.85 respectively (default values), and then obtaining a value (%) for identity (Karlin, S. and S. F. Altschul, Proc. Natl. Acad. Sci. USA 87:2264-68 1990; Karlin, S. and S. F. Altschul, Proc. Natl. Acad. Sci. USA 90:5873-7 1993).
The proteins of the present invention, or proteins functionally equivalent to those proteins, may be proteins subjected to various modifications, such as physiological modification by glycoside chains, labeling with fluorescent, radioactive, or such substances, or fusion with another protein. In particular, the recombinants described later may be glycosylated differently depending on the host used for expression. However, even if there are differences in glycoside modification, if the proteins show characteristics similar to those of the S1-5 protein described in the present description, they are considered to be the S1-5 protein or a functionally equivalent protein of the present invention.
The S1-5 protein can be obtained not only as a biological material but also as a recombinant protein by incorporating a gene encoding this protein into an appropriate expression system. In order to obtain the S1-5 protein by genetic engineering methods, the aforementioned DNA encoding the S1-5 protein can be incorporated into a suitable expression system, and then expressed. Host/vector systems applicable to the present invention include, for example, expression vector pGEX and E. coli. Since pGEX enables a foreign gene to be expressed as a fusion protein with glutathione S-transferase (GST) (Gene, 67:31-40, 1988), pGEX carrying a gene encoding the S1-5 protein is transfected into an E. coli strain such as BL21 by heat shock, and after incubating for an appropriate period of time, isopropylthio-β-D-galactoside (IPTG) is added to induce expression of the GST-fused S1-5 protein. A gene encoding the S1-5 protein can be obtained by amplification using methods such as PCR, using a synoviocyte cDNA library or such as a template. Since the GST of the present invention adsorbs onto Glutathione Sepharose 4B, expression products can be easily separated and purified by affinity chromatography.
In addition, the following may be applied as a host/vector system for obtaining a recombinant S1-5 protein. First, when using bacteria as the host, one may use commercially available vectors for expressing fusion proteins, which use a histidine tag, HA tag, FLAG tag, or such. In the case of yeast, Pichia yeast is well known to be effective for expressing glycosylated proteins. In terms of glycosylation, expression using a baculovirus vector whose host is insect cells is also useful (Bio/Technology, 6:47-55, 1988). Furthermore, vectors that utilize promoters of CMV, RSV, SV40 or such can be transfected into mammalian cells, and all of these host/vector systems can be used as S1-5 protein expression systems. Genes can also be introduced using viral vectors such as retrovirus vectors, adenovirus vectors, or adeno-associated virus vectors.
The obtained proteins of the present invention can be isolated from the inside or outside (the media or such) of the host cells, and can be purified as substantially pure and homogeneous proteins. Without limitation, separation and purification of the proteins can be carried out using the separation and purification methods used for ordinary protein purification. For example, proteins can be separated and purified by appropriately selecting and combining column chromatography, filtration, ultrafiltration, salt precipitation, solvent precipitation, solvent extraction, distillation, immunoprecipitation, SDS-polyacrylamide gel electrophoresis, isoelectric focusing, dialysis, and recrystallization.
Examples of chromatography include affinity chromatography, ion exchange chromatography, hydrophobic chromatography, gel filtration, reverse phase chromatography, and adsorption chromatography (Marshak et al., Strategies for Protein Purification and Characterization: A Laboratory Course Manual. Ed Daniel R. Cold Spring Harbor Laboratory Press, 1996). These types of chromatography can be performed as liquid phase chromatography, such as HPLC or FPLC.
For the proteins of the present invention an expression system other than a cell-free system is preferably used. The proteins of the present invention are preferably proteins modified by physiological conformation, glycosylation, disulfide bond, lipidation, methylation, or such. The proteins of the present invention are preferably substantially purified proteins. Herein, “substantially purified” means that the purity of a protein of the present invention (the proportion of the protein of the present invention in the entire protein component) is 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, or 100% or close to 100%. Close to 100% the upper limit depends on the purification and analysis technique used by those skilled in the art, and is 99.999%, 99.99%, 99.9%, 99%, or such.
Proteins with the above-mentioned purity are included as substantially purified proteins, regardless of the purification method used for that protein. Examples of such include, without limitation, proteins substantially purified by appropriately selecting or combining the above-mentioned column chromatography, filtration, ultrafiltration, salt precipitation, solvent precipitation, solvent extraction, distillation, immunoprecipitation, SDS-polyacrylamide gel electrophoresis, isoelectric focusing, dialysis, recrystallization, and such.
The present invention also provides partial peptides (partial fragments) of the proteins of the present invention. The length of a partial peptide is not particularly limited, as long as the partial peptide is functionally equivalent to a protein of the present invention. An example of a partial peptide of the present invention is a peptide shorter than a protein of the present invention, and comprising the amino acid sequence of SEQ ID NO: 6. Using such a peptide can prevent or treat age-related diseases or symptoms, and inhibit osteoclast activity.
The present invention provides preventive or therapeutic agents for age-related diseases or symptoms, wherein the agents comprise a protein of the present invention or a partial peptide thereof (hereinafter referred to as proteins). An “age-related disease or symptom” is as described above. Furthermore, the present invention provides agents that inhibit osteoclast function, wherein the agents comprise a protein of the present invention. The proteins and such of these pharmaceutical agents are not particularly limited, as long as they are isolated, and can be used regardless of whether they are substantially purified or crude proteins, as long as they can be used as the above-mentioned pharmaceutical agents.
These pharmaceutical agents can be utilized as preventive or therapeutic agents for age-related diseases or symptoms, or as agents for inhibiting osteoclast function in humans or non-human animals (such as laboratory animals, livestock animals, and pet animals).
The proteins of the present invention may be administered after formulation by appropriate combination with pharmaceutically acceptable carriers or media, such as sterilized water or physiological saline, stabilizers, fillers, antiseptics, surfactants, chelating agents (EDTA and such), and binders.
Examples of the forms (dosage forms) of the pharmaceutical agents of the present invention include, without limitation, injections, freeze-dried agents, and solutions.
Administration to patients may be either oral or parenteral, but is preferably parenteral administration, such as administration by injection. Examples of administration by injection include systemic or local administration by intravenous injection, intramuscular injection, intraperitoneal injection, subcutaneous injection, and such.
The dose varies depending on the weight and age of the patient, the method of administration, symptoms, and such, but those skilled in the art can appropriately select suitable doses. The conventional dose differs depending on the effective blood concentration and metabolism time of the pharmaceutical agent, but the daily maintenance dose may be approximately 0.1 mg/kg to approximately 1.0 g/kg, preferably approximately 0.1 mg/kg to approximately 10 mg/kg, and more preferably approximately 0.1 mg/kg to approximately 1.0 mg/kg. The dose can be administered in one to several dosages.
The present invention provides antibodies that recognize the S1-5 proteins. Using the S1-5 protein of the present invention or a fragment thereof as the immunogen, antibodies against the S1-5 proteins may be obtained by known methods (Harlow, E. and Lane, D., Antibodies; A Laboratory manual. Cold Spring Harbor, N.Y., 1988; Kohler, G & Milstein, C., Nature 256: 495-7, 1975).
For immunization, an S1-5 protein of the present invention or fragment thereof was immunized into immunization animals with an appropriate adjuvant. The S1-5 protein fragment can be conjugated to a carrier protein to produce an immunogen. Keyhole limpet hemocyanin (KLH) or bovine serum albumin (BSA) may be used as a carrier protein for obtaining the immunogen.
Rabbits, mice, rats, goats, sheep, or such are conventionally used as animals for immunization. Freund's complete adjuvant (FCA) and such are conventionally used as the adjuvant (Adv. Tubercl. Res., 1:130-148, 1956). Boosters are given at appropriate intervals, and when an increase of antibody titer has been confirmed, blood is collected and antiserum can be obtained. Further purification of this antibody fraction can yield purified antibodies (polyclonal antibodies).
Monoclonal antibodies can be obtained by collecting antibody-producing cells and then cloning using cell fusion or the like. Monoclonal antibodies are important tools for accomplishing high sensitivity and specificity in immunoassays. As an alternative method for obtaining antibodies that recognize S1-5 proteins, a DNA encoding synoviolin can be randomly fragmented, and the fragments can be introduced into phage vectors to produce phage libraries that display domain peptides. Domains having immunological activity can be identified by immunoscreening such libraries using antibodies that recognize synoviolin.
Cells derived from immune animals can be used as antibody producing cells. Furthermore, chimeric antibodies and humanized antibodies can be constructed from the antibody genes of monoclonal antibody producing cells derived from immune animals obtained as described above. When administering antibodies to humans, animal antibodies are undesirable since they will be eliminated as foreign substances. Therefore, it is necessary to use chimeric antibodies, in which the constant regions of highly antigenic antibodies are substituted with those of human antibodies; or to use humanized antibodies in which the frameworks of the variable regions in addition to the constant regions are substituted with those of humans.
Chimeric antibodies or humanized antibodies that recognize a S1-5 protein of the present invention are useful for drug delivery systems (DDSs). With regards to DDSs that use antibodies that recognize a S1-5 protein of the present invention, examples of substances that may be useful when linked to an antibody include Fas ligands and anti-synoviolin antibodies.
The antibodies of the present invention can be used as immunological agents for detecting S1-5 proteins. Methods for using antibodies to immunologically detect proteins present in the tissues and blood are well known.
The antibodies of the present invention can be used to separate or detect S1-5 proteins, or cells that express S1-5 proteins. Protein isolation and purification methods using antibodies are well known to those skilled in the art. The S1-5 proteins of the present invention are used as markers for synoviocytes and human diploid fibroblast cells. More specifically, synoviocytes and human diploid fibroblasts can be detected or separated using S1-5 protein expression as an indicator. Antibodies are labeled appropriately using fluorescence and such. For example, cells expressing the S1-5 proteins can be separated by cell sorting using antibodies against the S1-5 proteins.
All prior art documents cited herein are incorporated herein by reference.
Herein below, the present invention will be specifically described using Examples. However, the present invention is not be construed as being limited thereto.
Using a cDNA expression library derived from the synoviocytes of RA patients, screening was carried out for factors that bind to synoviolin (Tadaomi Takenawa, Toshiki Watanabe, eds., Baiomanyuaru UP Shirizu “Tampakushitsu no Bunshikan Sogosayo Jikken Ho” [Bio-Manual UP Series “Experimental Methods for Protein Intermolecular Interactions”], pp. 66-67, Yodosha Co., Ltd.; Kaelin, W. G et al., Cell 70, 351-364, 1992; Skolnik, E. Y. et al., Cell 65, 83-90, 1991; Sambrook, J. et al., Molecular Cloning, a laboratory manual second edition, Cold Spring Harbor Laboratory Press 12.16-12.20, 1989). E. coli(XL1-BlueMRF′) was infected with the library phage by incubation for 20 minutes at 37° C., then mixed with top agarose and spread onto a plate. This was cultured for 3.5 hours at 42° C. A nitrocellulose membrane was then soaked in 10 mM IPTG; dried, and placed on the plate. Culturing was performed for an additional 3.5 hours at 37° C. The membrane was recovered, then washed five times for five minutes in a washing buffer [10 mM Tris-HCl (pH 8.0), 0.5% skim milk, 0.1% Triton X-100, 150 mM NaCl, 1 mM EDTA, 5 mM MgCl2, 1 mM DTT, protease inhibitor (complete, Boehringer Mannheim Corporation)] and soaked for one hour in a blocking buffer [10 mM Tris-HCl (pH 8.0), 5% skim milk, 0.1% Triton X-100, 150 mM NaCl, 1 mM EDTA, 5 mM MgCl2, 1 mM DTT, 5% glycerol, protease inhibitor (complete, Boehringer Mannheim Corporation)]. After the five-minute washing was performed five times with the washing buffer, GST-Synoviolin 32P-labeled with protein kinase A was added as a probe (approximately 106 cpm/ml), and incubation was performed. Washing was performed repeatedly while changing the washing buffer until the count per membrane was approximately 1 kcpm, and then the signal was detected by autoradiography. As a result, a clone bound to Synoviolin was obtained. The nucleotide sequence of the cDNA of this clone was determined for the 100 bp nearest its 5′ end and the 100 bp nearest its 3′ end. Database searches were performed based on the obtained nucleotide sequence information, and the sequences in the 100 bp end portions were found to be the same as those of a known gene: S1-5 (also called EFEMP-1, FBNL, or FBLN-3) [Lecka-Czernik, B. et al., Molecular and Cellular Biology, 15, 120-128, 1995; accession number U03877 (cDNA), AAA65590 (protein); Stone, E. M. et al., Nature Genetics 22, 199-202, 1999; accession number Q12805 (protein)]. The sizes of both genes and their translation products are roughly the same, suggesting that they are the same protein. In the present invention, the cDNA sequence and amino acid sequence of human S1-5 are shown in SEQ ID NOs: 1 and 2, respectively.
The lacZ gene was introduced into the translation initiation site of the mouse S1-5 gene fragment (the ATG codon that is translated into the first methionine) to construct a targeting vector. A neomycin resistance (neo) gene was inserted as a marker gene, and the diphtheria toxin A (DT-A) gene was also linked to enable exclusion of cell lines in which non-homologous recombination occurs. In the present invention, the cDNA sequence, amino acid sequence, and genomic sequence of mouse S1-5 are shown as SEQ ID NOs: 3, 4, and 5 respectively.
Electroporation was used to introduce the targeting vector of Example 1 into a mouse TT-2 cell strain, and cell lines in which homologous recombination occurred were selected. The obtained cells were injected into eight-cell stage embryos and either directly transplanted to the fallopian tubes of a surrogate mother, or transplanted to the uterus of a surrogate mother after being cultured for one day to develop into a blastocyst. The obtained heterozygous mutant mice (F1) were crossed with each other to obtain heterozygous and homozygous mutant mice. In the mutant mice thus obtained, tissues that should express S1-5 will express LacZ protein (β-galactosidase) instead.
Genotype was confirmed using Southern blot analysis. DNA was extracted from the mice about two weeks after birth, at a point roughly 3 mm from the tip of the tail. The obtained DNA was digested with restriction enzyme BamHI before use. Bands were detected at 2.4 kbp in the wild type, at 5.4 kbp in homozygous mutant mice, and at both positions in heterozygous mutant mice. Northern blot analysis could not confirm mRNA expression of the S1-5 gene.
S1-5 knockout mice aged 13 to 117 weeks (three to 29 months) were analyzed using autopsy and X-ray photography. As a result, older mice (eight months or older) were observed to have kyphosis, decreased bone amount, hair loss, facial skin injuries, necrosis of the nails, breast hypertrophy, ascites, liver tumors, blood clots in the ocular fundus and adipose tissues, and uterine swelling (
An incision was made in the tails of S1-5 knockout mice aged eight to 111 weeks (26 months), and to examine the degree of hemostasis, filter paper was used every ten seconds to absorb the blood flowing out. The results showed that hemostasis tends to be difficult to achieve in S1-5 knockout mice (
One end of a capillary tube for hematocrit measurements (Capillary tubes for microhematocrits, 75 mm length, heparinized, Drummond Scientific Co.) was placed into the blood and maintained at an appropriate angle to draw the blood by capillary action up two-thirds of the full length of the capillary tube. The end from which blood was drawn was sealed by insertion of putty. The capillary, sealed at one end, was centrifuged for five minutes at 11,000 rpm, and the percentage (%) was read using a measuring plate. The results showed that S1-5 knockout mice tended to have low hematocrit values, and were in an anemic condition (
Blood was collected from the tail vein of 15- to 110-week old S1-5 knockout mice. This blood was then diluted 1000 times in PBS, cytospun (800 rpm, five minutes), and then peripheral blood was stained using Giemsa. The results showed anemia in the S1-5 knockout mice: specifically, a decreased number of erythrocytes, abnormal erythrocytes (circular erythrocytes), and differences in staining were observed (
To numerically describe the spinal curvature of S1-5 knockout mice, the angle of curvature was measured using X-ray photographs. As a result, few wild type individuals had an angle of curvature of 95° or less, whereas S1-5 knockout mice with an angle of curvature of 95° or less were frequently found. Therefore, onset of kyphosis was defined as an angle of curvature of 95° or less, and the rate of onset was calculated every 21 weeks of age. Compared to males, females had a higher onset frequency, with earlier onset from about 22 weeks of age (
Since S1-5 knockout mice showed abnormalities in the bone tissues, more detailed analysis was carried out using peripheral quantitative computed tomography (pQCT) measurements at Elk Corporation. The results indicated decreased bone mineral content and bone mineral density in S1-5 knockout mice (
The bone tissues were also TRAP stained to confirm the number of osteoclasts in the tissue. Images of each well were taken at equivalent magnification and captured into a computer, then Image J (distributed by NIH) was used to draw a line around parts corresponding to osteoclasts, and the area was calculated in pixels. The results showed that the number of osteoclasts (
Using bone marrow cells derived from S1-5 knockout mice, the ability to form osteoclasts in vitro was analyzed. 1×105 bone marrow cells were plated onto a 96-well plate, and then macrophage colony stimulating factor (M-CSF) was added to a final concentration of 50 ng/mL. Two days later Receptor Activator of NF-κB Ligand (RANKL) was added to a final concentration of 10, 30, and 100 ng/mL. The cells were fixed seven days later, and then TRAP stained to examine their osteoclast-forming ability (
CHO-K1 cells stably expressing human S1-5-His were prepared in order to carry out large-scale purification of the secretory S1-5-His protein. Using Lipofectamine 2000, 20 μg of pCAGGS-S1-5-His and 0.7 μg of pcDNA3 were cotransfected into CHO-K1 cells (one 10-cm dish), and on the next day the cells were diluted ten times and plated onto six 10-cm dishes. The following day, selection was initiated by using 800 μg/mL Geneticin, and colonies were picked 11 days later. 16 colonies were picked from each 10-cm dish (a total of 96 clones) and these colonies were plated into a 96-well plate, then scaled up into 24-well plates, and then to 6-well plates. At the same time, six types of bulk samples were individually plated onto 10-cm dishes, and when they reached confluency, the media were exchanged for serum-free media. 24 hours later, the culture supernatant was precipitated with TCA to check S1-5-His expression (
60 mL of the cell culture supernatant of CHO-K1 stably expressing S1-5-His was passed through a filter, and then concentrated to approximately 10 mL using Centriplus. The concentrated sample was then dialyzed against a purification buffer (20 mM Tris-HCl (pH 7.5), 500 mM NaCl, 10% glycerol). The dialyzed sample was loaded onto a 1-mL HisTrap column, and the column was washed with 10 mL of purification buffer. The adsorbed protein was then eluted using the purification buffer supplemented with 10 mM and 250 mM imidazole (1 mL/fraction). The proteins contained in the fraction eluted with the 250 mM imidazole solution were separated by 10% SDS-PAGE, and then detected using silver staining (
280 mL of the culture supernatant of CHO-K1 cell stably expressing S1-5-His was passed through a filter (0.22 μm) and then loaded onto a 1-mL HisTrap column. The column was washed with 10 mL of purification buffer (20 mM Tris-HCl (pH7.5), 500 mM NaCl, 10% glycerol) and then with the purification buffer supplemented with 10 mM imidazole. The adsorbed protein was then eluted with the purification buffer supplemented with 50 mM and 100 mM of imidazole (1 mL/fraction). The eluted fractions were collected (approximately 4 mL), and dialyzed overnight against 1 L of PBS, and the sample was then passed through a filter (0.22 μm). The proteins included in the fractions eluted with 50 mM and 100 mM imidazole were separated by 10% SDS-PAGE, and then detected using silver staining (
The S1-5 sequence comprises six EGF-like domains. To investigate the function of human S1-5, the EGF-like domains were deleted one at a time from the C-terminal end, producing six constructs (
S1-5-E1-His/pME18S, S1-5-E1-2-His/pME18S, S1-5-E1-3-His/pME18S, S1-5-E1-4-His/pME18S, S1-5-E1-5-His/pME18S, S1-5-E1-6-His/pME18S and S1-5 full-His/pME18S were transfected into CHO-K1 cells using FuGENE6 (Roche). Eight hours after transfection the media were exchanged for serum-free media, and the cells were then cultured for 24 hours. Culture supernatants were collected, Ni-agarose was added to them, and they were mixed for eight hours at 4° C. The Ni-agarose was washed three times with a washing buffer (20 mM Tris (pH7.5), 500 mM NaCl, 10% Glycerol, and 10 mM Imidazole), and then the S1-5 proteins were eluted using an elution buffer (20 mM Tris (pH7.5), 500 mM NaCl, 10% Glycerol, 250 mM imidazole). The eluted fractions were dialyzed to exchange the buffer for PBS, and then the concentration of S1-5 proteins were determined by Western blotting (
HEK293 cells (Dainippon Pharmaceutical) were plated to 80% to 90% confluency in a 150-mm dish (IWAKI). The following day, transfection was carried out using FuGENE6. The procedure was carried out as per the attached manual. The cells were collected two days later, and 300 μL of lysis buffer (50 mM Tris-HCl (pH 7.4), 420 mM NaCl, 1 mM EDTA, 1 mM MgCl2, 0.5 mM DTT, and 1 mM PMSF) was added. This was incubated on ice for 20 minutes. 100 μL of anti-FLAG antibody (SIGMA) bound to agarose beads was added and incubated overnight while rotating at 4° C. The beads were washed five times with washing buffer (50 mM Tris-HCl (pH7.4), 150 mM NaCl, 0.5 mM DTT, and 1 mM PMSF), then 100 μL of 100 μg/mL FLAG peptide (SIGMA) was added, and this was incubated for two hours while rotating at 4° C. The supernatants were collected by centrifugation, and 10 μL of each were subjected to SDS-PAGE. The FLAG-S1-5 proteins purified from the cells were identified by Western blotting (
The culture supernatants were collected 48 hours after transfection, at which point 100 μL of anti-FLAG antibody bound to agarose beads was added. These were then incubated overnight while rotating at 4° C. Thereafter, the same procedure as described above was carried out, and FLAG-S1-5 purified from the culture supernatants were identified and their concentrations were determined (
Colonies of E. coli that were transformed with a pGEX vector that expresses the GST-fused S1-5-His were isolated. The isolated colonies were inoculated into 10 mL of LB-ampicillin medium (50 mg/ml ampicillin, hereinafter the same), and cultured overnight at 37° C. (pre-culture). The pre-cultured E. coli was added to 200 mL of LB-ampicillin medium and cultured for 2.5 hours at 37° C. (main culture). IPTG was then added at a final concentration of 0.5 mM, and the mixture was cultured for another three hours at 30° C. The bacterial cells were collected by centrifugation, then 5 mL of BC500 (20 mM Tris-HCl (pH 8.0), 0.5 mM EDTA, 500 mM KCl, 20% glycerol, 1% NP-40, 1 mM DTT, 0.5 mM PMSF, 1 μg/mL of aprotinin, pepstatin, and leupeptin) and 100 μL of 100 μg/mL lysozyme was added to produce a suspension. The bacteria were then homogenized by sonication. The supernatant was collected by centrifugation, 500 μL of GSH resin (glutathione S transferase-conjugated agarose beads) (Pharmacia) was added, and the mixture was incubated overnight while rotating at 4° C. The GSH resin was washed five times with BC500, and then applied to a micro-column (Biorad). The column was capped after adding 500 μL of prescission protease (Pharmacia) solution (10U prescission protease, 50 mM Tris-HCl (pH7.0), 150 mM NaCl, 1 mM EDTA, 1 mM DTT), and was left to stand for 24 hours of incubation at 4° C. The column eluate was collected as a digested S1-5-His solution, identified using Western blotting (
The effect of purified S1-5-His protein on in vitro osteoclast-forming ability was examined using bone marrow cells derived from S1-5 knockout mice and the S1-5 protein purified from CHO-K1 cells in Example 11. 1×105 bone marrow cells were plated onto a 96-well plate, M-CSF was added at a final concentration of 50 ng/mL, and two days later RANKL was added to a final concentration of 100 ng/mL. S1-5 was diluted in PBS, and was added continuously to the culture medium from the time of M-CSF addition, such that the final concentrations were 0, 10, 30, and 100 ng/mL. Five days later the cells were fixed and the effect of S1-5 on osteoclast-forming ability was examined using TRAP staining. The experiments were carried out at n=5. The results confirmed that the number of TRAP-positive multinucleated giant cells was significantly suppressed depending on S1-5 concentration (
The effect of purified S1-5-E1-2 protein on in vitro osteoclast-forming ability was examined using bone marrow cells derived from S1-5 knockout mice and the S1-5-E1-2 protein purified from CHO-K1 cells in Example 16. The method was as for Example 15, except that S1-5-E1-2 protein was added at a final concentration of 0 and 10 ng/mL. The results confirmed that the S1-5 truncated protein suppressed the number of TRAP-positive multinucleated cells (
Using RAW264.7 cells (mouse macrophage-derived cells) and the S1-5 protein purified in Example 11, which was derived from the culture supernatant of CHO-K1 cells, the effect of the S1-5 protein on in vitro osteoclast-forming ability was examined. 2.5×105 RAW264.7 cells were plated onto a 96-well plate, and RANKL was added to a final concentration of 100 ng/mL. The S1-5 protein was diluted in PBS, and was continuously added to the culture medium to final concentrations of 0, 10, 30, 100, 200, and 500 ng/mL. Three days later, the cells were fixed, and the effect of S1-5 on osteoclast-forming ability was examined using TRAP staining. The experiments were carried out at n=5. The results confirmed S1-5 concentration-dependent suppression of the number of TRAP-positive multinucleated cells (
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-197035 | Jul 2004 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP05/12251 | 7/1/2005 | WO | 00 | 3/19/2009 |
