Gene expression and DNA methylation analysis at the OA susceptibility locus marked by rs6516886 prioritizes specific gene and regulatory sequences as functional targets of the association signal

Abstract

regulation of key ECM components in OA synovial fibroblasts. Next, we employed "Watson Discovery tool" to identify direct targets of miR-27b-3p to further elucidate its signalling pathway. This tool identified a panel of 11 genes including peroxisome proliferator-activated receptor gamma (PPARg) as direct targets for miR-27b-3p. Indeed, we confirmed that miR-27b-3p mimic treatment results in a marked suppression of PPARg expression, while inhibition of miR-27b-3p upregulates PPARg, suggesting that miR-27b-3p may impart its ECM regulatory effect through modulation of PPARg. Furthermore, ISH of DMM-induced OA mice knee joints further show that miR-27b-3p expression is prominent in the synovial lining and fibrocartilage compared to sham control mice in vivo. Conclusions: Our results thus far suggest that, in OA synovial fibroblasts, miR-27b-3p is involved in the regulation of key ECM components. Our data also suggest that miR-27b-3p may signal via negative regulation of PPARg. Our ongoing studies are confirming if miR-27b-3p signalling via PPARg controls ECM regulation in OA synovial fibroblasts. Our in vivo studies show that miR-27b-3p expression is elevated in the synovium during OA. To comprehensively investigate the endogenous role of miR-27b-3p in synovial pathology, we have intra-articularly injected mouse knee joints with the in-vivo grade mimic of miR-27b-3p to determine any changes in the synovium upon miR-27b-3p treatment in vivo.