BACKGROUND: The essence of osteoporosis is mainly the imbalance of bone formation and absorption. Previous studies indicated that SIRT1 is closely related to bone metabolism and bone mass as a regulator of bone mass. The literature reports that microRNAs are significant regulators of osteoblast proliferation and differentiation.

MATERIAL AND METHODS: In this study, SIRT1 protein and mRNA levels were examined by Western blot and RT-PCR. Osteogenic proliferation was examined by CCK8 assay and osteogenic markers, including ALP, OCN, and RUNX2, were examined by ELISA. The target of miR-132-3p was identified by luciferase reporter assay.

RESULTS: LPS downregulated the SIRT1 protein level and β-glycerophosphate upregulated the SIRT1 protein level. The results demonstrated that SIRT1 overexpression promoted the proliferation and differentiation in MC3T3-E1 cells, and SIRT1 interference had the opposite effect. Luciferase reporter assay revealed that miR-132-3p inhibited the reporter gene activity of SIRT1. LPS upregulated the mRNA level of miR-132-3p, and β-glycerophosphate downregulated the mRNA level of miR-132-3p.

CONCLUSIONS: miR-132-3p is a pivotal regulator in osteogenic proliferation and differentiation by targeting SIRT1.

Keywords: Osteoblasts, Sirtuin 1, 3T3 Cells, Alkaline Phosphatase, Gene Expression Regulation, Lipopolysaccharides, osteocalcin, Osteogenesis, Osteoporosis