Abstract
Osteoarthritis is a common disease in joint cartilages. Because the molecular pathogenesis of osteoarthritis remains elusive, early diagnostic markers and effective therapeutic agents have not been developed. To understand the molecular mechanisms, we attempted to identify transcription factors involved in the onset of osteoarthritis. Microarray analysis of mouse articular cartilage cells indicated that retinoic acid, a destructive stimulus in articular cartilage, up-regulated expression of sex-determining region Y-box (Sox)4, a SoxC family transcription factor, together with increases in Adamts4 and Adamts5, both of which are aggrecanases of articular cartilages. Overexpression of Sox4 induced a disintegrin-like and metallopeptidase with thrombospondin type 4 and 5 motif (ADAMTS4 and ADAMTS5, respectively) expression in chondrogenic cell lines C3H10T1/2 and SW1353. In addition, luciferase reporter and chromatin immunoprecipitation assays showed that Sox4 up-regulated ADAMTS4 and Adamts5 gene promoter activities by binding to their gene promoters. Another SoxC family member, Sox11, evoked similar effects. To evaluate the roles of Sox4 and Sox11 in articular cartilage destruction, we performed organ culture experiments using mouse femoral head cartilages. Sox4 and Sox11 adenovirus infections caused destruction of articular cartilage associated with increased Adamts5 expression. Finally, SOX4 and SOX11 mRNA expression was increased in cartilage of patients with osteoarthritis compared with nonosteoarthritic subjects. Thus, Sox4, and presumably Sox11, are involved in osteoarthritis onset by up-regulating ADAMTS4 and ADAMTS5.-Takahata, Y., Nakamura, E., Hata, K., Wakabayashi, M., Murakami, T., Wakamori, K., Yoshikawa, H., Matsuda, A., Fukui, N., Nishimura, R. Sox4 is involved in osteoarthritic cartilage deterioration through induction of ADAMTS4 and ADAMTS5.