Abstract
Osteoarthritis (OA) is the most common degenerative disorder, affecting approximately half of the elderly population. In this study, we find that the expressions of long noncoding RNA (lncRNA) IGFBP7-OT and its maternal gene, IGFBP7, are upregulated and positively correlated in osteoarthritic cartilage. Overexpression of IGFBP7-OT significantly inhibits chondrocyte viability, promotes chondrocyte apoptosis, and reduces extracellular matrix components, whereas IGFBP7-OT knockdown has the opposite effects. IGFBP7-OT overexpression promotes cartilage degeneration and markedly aggravates the monosodium iodoacetate-induced OA phenotype in vivo. Further mechanistic research reveals that IGFBP7-OT promotes OA progression by upregulating IGFBP7 expression. Specifically, IGFBP7-OT suppresses the occupancy of DNMT1 and DNMT3a on the IGFBP7 promoter, thereby inhibiting methylation of the IGFBP7 promoter. The upregulation of IGFBP7-OT in OA is partially controlled by METTL3-mediated N6-methyladenosine (m6A) modification. Collectively, our findings reveal that m6A modification of IGFBP7-OT promotes OA progression by regulating the DNMT1/DNMT3a-IGFBP7 axis and provide a potential therapeutical target for OA treatment.