Hypoxia-Induced MicroRNA-429 Promotes Differentiation of MC3T3-E1 Osteoblastic Cells by Mediating ZFPM2 Expression.

BACKGROUND/AIMS Hypoxia has been reported to regulate osteoblastic differentiation of bone cells and cartilage development. However, information concerning the molecular mechanisms remains largely unknown. METHODS The expression of miR-429 was evaluated by quantitative real-time PCR analysis. To test whether miR-429 directly regulate the expression level of ZFPM2 at transcription level, dual-luciferase reporter gene assay was performed. Western blotting was performed to detect osteogenesis related protein expression. The cell proliferation, apoptosis, alkaline phosphatase activity and matrix mineralization were performed to assess the functions of miR-429 in vitro and in vivo the effects of miR-429 on fracture healing. RESULTS Expression of miR-429 was increased in MC3T3-E1 cells treated with 200 μM CoCl2 by qRT-PCR, and overexpression of miR-429 promoted cell differentiation, and enhanced alkaline phosphatase activity and matrix mineralization. Luciferase reporter assays suggested that miR-429 directly targets the 3'UTR of ZFPM2. In addition, knockdown of ZFPM2 could phenocopy the effects of miR-429 expression. Furthermore, overexpression of ZFPM2 in miR-429-expressing MC3T3-E1 cells suppressed cell differentiation. CONCLUSIONS Our results provide valuable insight into the potential role of hypoxia in regulation of osteoblastic cell differentiation.