Expression of Sp7 in Satb2-induced osteogenic differentiation of mouse bone marrow stromal cells is regulated by microRNA-27a.

Satb2 is a special AT-rich binding transcription factor essential for osteoblast differentiation and bone formation. Specific microRNAs (miRNAs) have been identified to regulate the complex process of osteogenic differentiation. It remains unclear how miRNA expressions is changed in the Satb2-induced osteogenic differentiation of bone marrow stromal cells (BMSCs). From the miRNA expression profile data collected by us from Satb2-induced osteogenic differentiation of mouse BMSCs, we found that miR-27a was significantly down-regulated relative to non-treated cells 7 days post induction. By in silico analysis, we identified Sp7 as a miR-27a targeting gene and verified the findings by Western blot analysis, qRT-PCR, and luciferase reporter assays. We also analyzed the function of miR-27a in osteogenic differentiation by transfection of exogenous miR-27a into BMSCs. Overexpression of miR-27a remarkably inhibited the expression of Sp7 and attenuated Satb2-induced osteogenic differentiation. Our results suggest that expression of Sp7 during the early stage of Satb2-induced osteogenic differentiation of BMSCs is regulated by miR-27a.