MiR-25 promotes proliferation, differentiation and migration of osteoblasts by up-regulating Rac1 expression

According to many studies, miRNAs are involved in the control of bone cell differentiation and function. Hence, an understanding of the pathways regulated by miRNAs involved in skeletal function is essential for the development of miRNA-based therapeutic strategies for bone diseases. In this study we evaluated the role of miR-25 in osteoblast differentiation by examining the expressions of key osteoblast differentiation markers like Runx2 and Ocn and also evaluated the effects of miR-25-Rac1 axis on PI3K/AKT and JNK pathways. MC3T3-E1 osteoprogenitors were treated with osteogenic differentiation media which was refreshed every 48 h after the initial differentiation treatment and were then quantified for total miRNA content. The viability, migration as well as Runx2 and Ocn expressions in cells transfected with miR-25 mimic, miR-25 inhibitor, and si-Rac1 were evaluated by CCK-8 assay, wound migration assay, qRT-PCR and Western blot. Finally, the effects of miR-25-Rac1 axis on PI3K/AKT and JNK pathways were studied. MiR-25 was found to significantly enhance cell viability and migration and up-regulate the expressions of Runx2 and Ocn. MiR-25 was also found to enhance the expression levels of Rac1, which contributed to the effects of miR-25 on osteoblastic cell lines. MiR-25 activated PI3K/AKT and JNK pathways possibly by up-regulation of Rac1. Enhanced expression of miR-25 led to the promotion of cell viability and migration, as well as up-regulation of Runx2 and Ocn markers by enhancing Rac1 expression.