miR-145 suppresses osteogenic differentiation by targeting Sp7

Osteogenesis depends on a coordinated network of transcription factors including Sp7. Emerging evidence indicates that microRNAs (miRNAs) act as pivotal regulators in various biological processes including osteoblast proliferation and differentiation. Here, we investigated the effect of miR-145 on osteogenic differentiation. miR-145 was decreased during osteogenic differentiation, which could suppress the osteogenic differentiation of C2C12 and MC3T3-E1 cells confirmed by gain- and loss-of-function experiments. Moreover, bioinformatic analysis combined with luciferase reporter assay, and Western blot validated that miR-145 negatively regulated Sp7 expression. Inhibition of Sp7 showed similar effect with miR-145 on osteogenic differentiation, whereas overexpression of Sp7 attenuated this effect. Collectively, these data indicate that miR-145 is a novel regulator of Sp7, and it suppresses the osteogenic differentiation of C2C12 and MC3T3-E1 cells.