miR-146a-5p targets Sirt1 to regulate bone mass

MicroRNAs (miRNAs) have been proven to serve as key post-transcriptional regulators, affecting diverse biological processes including osteogenic differentiation and bone formation. Recently, it has been reported that miR-146a-5p affects the activity of both osteoblasts and osteoclasts. However, the target genes of miR-146a-5p in these procedures remain unknown. Here we identify miR-146a-5p as a critical suppressor of osteoblastogenesis and bone formation. We found that miR-146a-5p knockout mice exhibit elevated bone formation and enhanced bone mass in vivo. Consistently, we also found that miR-146a-5p inhibited the osteoblast differentiation of bone marrow mesenchymal stem cells (BMSCs) in vitro. Importantly, we further demonstrated that miR-146a-5p directly targeted Sirt1 to inhibit osteoblast activity. Additionally, we showed that the expression of miR-146a-5p gradually increased in femurs with age not only in female mice but also in female patients, and miR-146a-5p deletion protected female mice from age-induced bone loss. These data suggested that miR-146a-5p has a crucial role in suppressing the bone formation and that inhibition of miR-146a-5p may be a strategy for ameliorating osteoporosis.