MiR-125a-3p negatively regulates osteoblastic differentiation of human adipose derived mesenchymal stem cells by targeting Smad4 and Jak1.

Osteogenesis is a complex process which relies on the coordination of signals and transcription factors. Recent evidence indicates that microRNAs (miRNAs) act as important post-transcriptional regulators in a large number of biological processes including osteoblast differentiation. In this study, we investigated the expression and biological effect of miR-125a-3p during osteogenic differentiation of human adipose derived mesenchymal stem cells (hADSCs). We observed an obvious decrease in miR-125a-3p level during osteogenic differentiation. By using gain - and loss-of function experiments, we noticed that miR-125a-3p could suppress the osteogenic differentiation of hADSCs. Moreover, miR-125a-3p over-expression in hADSCs by transfection with miR-125a-3p mimics significantly inhibited cell proliferation by MTT. Flow cytometry analysis further demonstrated that forced expression of miR-125a-3p induced cell cycle G(1)/S phase arrest and apoptosis. In addition, we performed bioinformatic analysis, luciferase reporter assay and western blot to confirm that miR-125a-3p could regulate Smad4 and Jak1 expression negatively. Meanwhile, Smad4 and Jak1 were up-regulated after osteogenic differentiation and the down-regulation of endogenous Smad4 and Jak1 suppressed the osteogenic differentiation of hADSCs. Taken together, these data indicated that miR-125a-3p is Smad4 and Jak1 regulator, and it has a crucially physiological function in osteogenic differentiation of hADSCs.