miR-134 inhibits chondrogenic differentiation of bone marrow mesenchymal stem cells by targeting SMAD6

Various of microRNAs (miRNAs) have been reported to regulate the chondrogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), however, whether miR-134 plays a role in this biological process remains undetermined. In this present study, we firstly evaluated the chondrogenic differentiation of BMSCs by Alcian blue staining, and examined the miR-134 expression by qRT-PCR during this process. And miR-134 inhibitor was used to investigate the functions of miR-134 in chondrogenic differentiation of BMSCs by Alcian blue staining, qRT-PCR and western blot. Subsequently, the correlation between miR-134 and SMAD6 was assessed via bioinformatics analysis and dual luciferase reporter assay. Finally, the roles of SMAD6 in chondrogenic differentiation of BMSCs was also determined through Alcian blue staining, qRT-PCR and western blot. As results showed that miR-134 expression was significantly downregulated during chondrogenic differentiation, and inhibition of miR-134 obviously promoted chondrogenic differentiation. Dual luciferase reporter assay indicated that miR-134 could directly targeted the 39-UTR of SMAD6, inhibited miR-134 expression in BMSCs could upregulate SMAD6 expression. Moreover, we found that overexpression of SMAD6 significantly promoted chondrogenic differentiation, and this SMAD6 induced promotion of chondrogenic differentiation could be reversed by miR-134 mimics. In conclusion, our findings suggested that miR-134 may act as a negative regulator during chondrogenic differentiation of BMSCs by interacting with SMAD6.