TNF-α-induced NF-κB activation upregulates microRNA-150-3p and inhibits osteogenesis of mesenchymal stem cells by targeting β-catenin.

Although systemic or local inflammation, commonly featured by cytokine activation, is implicated in patients with bone loss, the underlying mechanisms are still elusive. As microRNAs (miR), a class of small non-coding RNAs involved in essential physiological processes, have been found in bone cells, we aimed to investigate the role of miR for modulating osteogenesis in inflammatory milieu using human bone marrow mesenchymal stem cells (hBM-MSCs). Induced by proinflammatory cytokine TNF-α, miR-150-3p was identified as a key player in suppressing osteogenic differentiation through downregulating β-catenin, a transcriptional co-activator promoting bone formation. TNF-α treatment increased the levels of miR-150-3p, which directly targeted the 3'-UTR of β-catenin mRNA and in turn repressed its expression. In addition, we observed that miR-150-3p expression was increased by TNF-α via IKK-dependent NF-κB signalling. There are three putative NF-κB binding sites in the promoter region of miR-150, and we identified -686 region as the major NF-κB binding site for stimulation of miR-150 expression by TNF-α. Finally, the osteogenic differentiation of hBM-MSCs was inhibited by either miR-150-3p overexpression or TNF-α treatment, which was prevented by anti-miR-150-3p oligonucleotides. Taken together, our data suggested that miR-150-3p integrated inflammation signalling and osteogenic differentiation and may contribute to the inhibition effects of inflammation on bone formation, thus expanding the pathophysiological functions of microRNAs in bone diseases.