The miR-548d-5p/SP1 signaling axis regulates chondrocyte proliferation and inflammatory responses in osteoarthritis

Abstract

Chondrocyte apoptosis and dysfunction play an important role in osteoarthritis (OA), a chronic progressive arthropathy. Non-coding RNAs have been implicated in OA pathogenesis. In this study, microRNA (miR)-548d-5p was found to be downregulated in OA samples and IL-1β-stimulated chondrocytes. miR-548d-5p overexpression partially reversed IL-1β-induced chondrocyte damage in vitro, evidenced by the promotion of cell growth, the inhibition of apoptosis and inflammatory cytokine release, and the improvement in extracellular matrix (ECM) deposition. Furthermore, miR-548d-5p overexpression partially reversed papain-induced damages on OA rat’s knee articular cartilage. Specificity protein 1 (SP1) was inhibited by miR-548d-5p and identified as its direct downstream target. In IL-1β-stimulated chondrocytes, SP1 overexpression significantly attenuated the protective effects of miR-548d-5p overexpression against chondrocyte damage. In conclusion, miR-548d-5p was abnormally downregulated in OA samples and IL-1β-stimulated chondrocytes. miR-548d-5p protects against IL-1β-induced chondrocyte damage via direct inhibition of SP1.