title: Expression of HOXD9 in fibroblast-like synoviocytes from rheumatoid arthritis patients.
abstract: The proteins of homeobox (HOX) genes are transcription regulators involved in cell type-specific differentiation and patterning of the body plan in vertebrates. Particularly, the HOXD family is involved in limb formation in mice and chicks. There is also some evidence that the HOXD9 gene, a member of the HOXD family, is involved in the pathology of rheumatoid arthritis (RA). The purpose of the present study was to determine if the HOXD9 protein was expressed in RA synovium and then to characterize the HOXD9-expressing cell. Western blotting and immunohistochemical analysis showed that the HOXD9 protein was expressed in the synovium from patients with RA, but not in those from patients with osteoarthritis or healthy individuals. The HOXD9-positive cells were localized in both the lining and sublining areas of the synovium. Furthermore, fluorescent double-staining showed that the HOXD9 protein was expressed in fibroblast-like synoviocytes (FLS). These findings not only indicate that the HOXD9 gene is exclusively expressed in the RA synovium but also suggest that the HOXD9 gene contributes to the pathology of rheumatoid arthritis through the FLS.
authors.affiliation: Rheumatology, Immunology and Genetics Program, Institute of Medical Science, St. Marianna University, School of Medicine, Kawasaki 216-8512, Japan.
authors.forename: Ngoc Chau
authors.initials: NC
authors.lastname: Nguyen
authors.forename: Takuji
authors.initials: T
authors.lastname: Hirose
authors.forename: Minako
authors.initials: M
authors.lastname: Nakazawa
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Kobata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakamura
authors.forename: Kusuki
authors.initials: K
authors.lastname: Nishioka
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Nakajima
mesh_terms: D001172:Arthritis, Rheumatoid / Q000378:metabolism*; D015153:Blotting, Western; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D005455:Fluorescent Antibody Technique; D018398:Homeodomain Proteins; D006801:Humans; D007150:Immunohistochemistry; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D013583:Synovial Membrane / Q000166:cytology / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; C088822:HOXD9 protein, human; D018398:Homeodomain Proteins; D009363:Neoplasm Proteins