MiR-106b Regμlates Osteogenic Differentiation Of MSCs And Bone Formation In Vivo By Regulating BMP2

Aim: Micro RNAs as a gene regμlator were involved in many biological processes. Bone morphophogenetic protein 2(BMP2) plays an important role in osteogenesis. We investigate the mechanism of the effect of mi R-106 b on osteogenic differentiation of MSCs and bone formation in glucocoticoid induced osteoporosis(GIOP) mice.Methods: Real-time PCR(q RT-PCR Taq Man probe or EVA Green) was carried out to determine the expression of mi R-106 b and osteo-associated genes during osteogenic differentiation. The relationship between mi R-106 b and BMP2 was forecasted by bioinformatics. mi R-106 b mimic and inhibitor were synthesized to knockout and overexpression of mi R-106 b to assess the effect of mi R-106 b on osteogenic differentiation of MSCs. Luciferase assay and Western Blot were implemented to confirm the relationship between mi R-106 b and BMP2. Then, Lentivirus-mediated mi R-106 b inhibitor vector was used to inhibit the expression of mi R-106 b in GIOP mice in-vivo.The effects of mi R-106 b inhibitor on GIOP were detected by micro-CT and histomorphometry. Osteogenic and osteoclastic markers on m RNA and protein level were detected by q PCR or ELISA.Results: mi R-106 b decreased during osteogenic differentiation of MSCs, and overexperssion of mi R-106 b could inhibit osteogenic differentiation. In Luciferase assay, mi R-106 b mimic led to a reduction of Luciferase activity. Mutagenesis of the seed sequence abolished the effects of mi R-16 b mimic on Luciferase activity. Also, overexpression of mi R-106 b decreased the m RNA and protein expression of BMP2 and lack of mi R-106 b caused a reverse effect on the m RNA and protein level of BMP2. In vivo, compared with GIOP mice, mi R-106 b inhibitor was able to increase bone mass,the number of osteoblast, bone formation rate, serum level of PINP, and the expression of BMP2, SMAD1 and SMAD5 also increased. Additionally, Serum level of CTx-1 was decreased by mi R-106 b inhibitor.Conclusions: We identified that mi R-106 b could inhibit osteogenic differentiation of mesenchymal stem cells(MSCs) by directly binding to BMP2 3’UTR and repressing expression of BMP2. Silencing of mi R-106 b signaling in mice increased bone formation by BMP2/SMAD signaling pathway, and protected against osteoporosis in glucocorticoid-induced osteoporosis(GIOP) mice.