Overexpression of miR-195-5p reduces osteoporosis through activating BMP-2/SMAD/Akt/ RUNX2 pathway via targeting SMURF1
Li Ye
Abstract
Osteoporosis (OP) is among the most common frequent chronic metabolic bone diseases in postmenopausal women. Here, the effect and underlying mechanisms of miR-195-5p in OP were investigated both in vivo and in vitro. In this study, the microgravity (MG) environment was simulated in MC3T3-E1 cells, and miR-195-5p overexpression or SMURF1 knockdown model was constructed to test their effects on the proliferation, apoptosis and osteogenic differentiation of MC3T3-E1 cells. Furthermore, an OVX mouse model was constructed in vivo, and adenovirus-loaded miR-195-5p mimics were administered to the mice to overexpress miR-195-5p. HE staining and µCT were adopted to observe pathological changes of femur. The targeted relationship between miR-195-5p and SMURF1 was predicted by bioinformatics analysis and verified by the dual-luciferase reporter assay and RNA immunoprecipitation (RIP) experiment. The results indicated that miR-195-5p was down-regulated in the head of femur of OP mouse model and MC3T3-E1 cells subjected to MG microenvironment. In addition, overexpression of miR-195-5p promoted MC3T3-E1 cell osteogenic differentiation and inhibited apoptosis. Mechanistically, SMURF1 is identified as a target of miR-195-5p, and overexpressing miR-195-5p activates the BMP-2/SMAD/Akt/RUNX2 signal by inhibiting the SMURF1 expression. Moreover, SMURF1 downregulation accelerated the osteogenic differentiation of MC3T3-E1 cells and attenuated MG-mediated apoptosis. In addition, upregulating miR-195-5p reduced osteoporosis in the OVX mouse model, accompanied with SMURF1 downregulation and BMP-2/SMAD/Akt/RUNX2 pathway activation. Collectively, miR-195-5p enhances osteogenic differentiation of osteoclast and relieve OP progression in the mouse model through activation of the BMP-2/SMAD/Akt/RUNX2 axis by targeting SMURF1.