MicroRNA-365 regulates IL-1β-induced catabolic factor expression by targeting HIF-2α in primary chondrocytes

Endothelial Per-Arnt-Sim domain protein-1/hypoxia-inducible factor-2 alpha (EPAS-1/HIF-2 alpha) is a catabolic transcription factor that regulates osteoarthritis (OA)-related cartilage destruction. Here, we examined whether microRNA-365 (miR-365) affects interleukin (IL)-1 beta-induced expression of catabolic factors in chondrocytes via regulation of HIF-2 alpha. MiR-365 levels were significantly decreased in human OA cartilage relative to normal cartilage. Overexpression of miR-365 significantly suppressed IL-1 beta-induced expression of HIF-2 alpha in human articular chondrocytes. Pharmacological inhibition of various IL-1 beta-associated signaling pathways revealed mitogen-activated protein kinase and nuclear factor-kappa B as the primary pathways driving IL-1 beta-mediated decreases in miR-365 and subsequent increase in HIF-2 alpha expression. Using a luciferase reporter assay encoding the 3' untranslated region (UTR) of human HIF-2 alpha mRNA, we showed that overexpression of miR-365 significantly suppressed IL-1 beta-induced up-regulation of HIF-2 alpha. AGO2 RNA-immunoprecipitation (IP) assay demonstrated that miR-365 and HIF-2 alpha mRNA were enriched in the AGO2-IP fraction in miR-365-transfected primary chondrocytes compared to miR-con-transfected cells, indicating that HIF-2 alpha is a target of miR-365. Furthermore, miR-365 overexpression significantly suppressed IL-1 beta-induced expression of catabolic factors, including cyclooxygenase-2 and matrix metalloproteinase-1, -3 and -13, in chondrocytes. In pellet culture of primary chondrocytes miR-365 prevented IL-1 beta-stimulated extracellular matrix loss and matrix metalloproteinase-13 expression. MiR-365 regulates IL-1 beta-stimulated catabolic effects in human chondrocytes by modulating HIF-2 alpha expression.