LncRNA RMRP promotes chondrocyte injury by regulating the FOXC1/RBP4 axis.

Introduction: The main pathological feature of osteoarthritis (OA) is chondrocyte injury. LncRNA mitochondrial RNA processing endoribonuclease (RMRP) has been shown to be a chondrogenic differentiation factor. This study aimed to explore the role of RMRP in chondrocyte injury.

Material and methods: Cell counting kit-8 (CCK-8) and TUNEL assays were used to determine lipopolysaccharide (LPS)-induced chondrocyte viability and apoptosis, respectively. The interaction between RMRP and FOXC1 was analyzed by RIP and RNA pull-down. Dual luciferase reporter and ChIP were employed to analyze the interaction between FOXC1 and RBP4. The levels of RMRP, FOXC1, RBP4, apoptosis-related and extracellular matrix (ECM)-related genes were detected by RT-qPCR and western blot. ELISA assay was used for detection of inflammatory cytokines in LPS-induced chondrocytes.

Results: The levels of RMRP, FOXC1 and RBP4 were significantly upregulated in OA cartilage tissues and LPS-induced chondrocytes. Knockdown of RMRP inhibited chondrocyte apoptosis and inflammation under LPS. RMRP interacted with FOXC1 and promoted RBP4 expression. FOXC1 could upregulate RBP4 and promote LPS-induced chondrocyte apoptosis and inflammation. Similarly, RMRP combined with FOXC1 and aggravated apoptosis and inflammation in LPS-treated chondrocytes.

Conclusions: RMRP promoted upregulation of RBP4 and activation of the JNK signaling pathway by binding to FOXC1, thereby accelerating LPS-induced apoptosis and inflammation in chondrocytes.