LncRNA MINCR attenuates osteoarthritis progression via sponging miR-146a-5p to promote BMPR2 expression

The purposes of this study are to explore the function and regulatory mechanism of a novel lncRNA MYC-Induced Long non-coding RNA (MINCR) in osteoarthritis (OA). The expression of lncRNA MINCR, miR-146a-5p, and bone morphogenetic protein receptor 2 (BMPR2), Sry-type high-mobility-group box 9 (SOX9), collagen type II alpha 1 (COL2A1), Aggrecan, metalloproteinase with thrombospondin motifs-4 (ADAMTS-4), Matrix metalloproteinase 3 (MMP3), MMP13, COL2A1, and Aggrecan were determined using quantitative real-time PCR (qRT-PCR), western blot, immunohistochemistry (IHC) and immunofluorescence (IF) in vitro and in vivo. And distribution and expression of MINCR were examined by fluorescence in situ hybridization (FISH). Cell proliferation and apoptosis were detected by cell counting kit-8 (CCK-8) assay, 5-Ethynyl-2'-deoxyuridine (EdU) staining, Annexin V-FITC/Propidium Iodide (PI), and Terminal Deoxynucleotidyl transferase-mediated dUTP Nick-End Labeling (TUNEL) staining in vitro and in vivo. The anterior cruciate ligament transection (ACLT) rat model was constructed to analyze the MINCR/miR-146a-5p/BMPR2 axis in vivo. The cartilage degeneration was determined by pathological staining with Hematoxylin and Eosin (H&E) and Safranin O staining. The binding relationship between MINCR and miR-146a-5p, and between miR-146a-5p and BMPR2 were determined by a dual-luciferase reporter gene, RNA Immunoprecipitation (RIP) assay, and RNA-pull down assays. Here, MINCR and BMPR2 were downregulated whereas miR-146a-5p was upregulated in OA cartilage tissues compared with control as well as IL-1 beta-induced chondrocytes compared with normal chondrocytes. Function experiments indicated that MINCR upregulation promoted cell proliferation and inhibited apoptosis and extracellular matrix (ECM)-degeneration. We also proved the binding relationship between MINCR and miR-146a-5p, and the BMPR2 acted as a target of miR-146a-5p. Mechanism analysis using rescue experiments in vitro and in vivo, MINCR silencing reversed the effects of miR-146a-5p downregulation in OA. Overexpression of miR-146a-5p also reversed the function of BMPR2 overexpression in OA. These data indicated that MINCR prevented OA progression via targeting miR-146a-5p to promote BMPR2 expression.