Synoviolin as a novel pathogenic factor for arthropathy

Rheumatoid arthritis (RA) is one of the most critical articular diseases with synovial hyperplasia followed by impairment of quality of life. However, the mechanism(s) that regulate synovial cell outgrowth is not fully understood. To clarify its mechanism(s), we carried out immunoscreening using antirheumatoid synovial cell antibody, and identified and cloned Synoviolin. Synoviolin was highly expressed in the rheumatoid synovium, and mice overexpressing this protein developed spontaneous arthropathy. Conversely, synoviolin^+/- mice were resistant to collagen-induced arthritis by enhanced apoptosis of synovial cells. We conclude that Synoviolin is a novel causative factor for arthropathy by triggering synovial cell outgrowth through its anti-apoptotic effects. Our findings provide a new pathogenetic model of RA, and suggest that Synoviolin could be targeted as a therapeutic strategy for RA.