Osteogenic differentiation and related gene expression mediated by mechanical strain

Liu Ming-yan; Li Yan; Qian Hong; Feng Yun-xia; Duan Yin-zhong; Li Yong-ming

doi:10.3969/j.issn.2095-4344.2013.50.002

Abstract：BACKGROUND:The regulatory role of extracellular signal regulated kinase 1/2 (ERK1/2) and nuclear factor kappa B (NF-κB) signal pathways in the osteogenic differentiation of MC3T3-E1 cells subjected to mechanical strain remains unclear. <br> OBJECTIVE:To investigate the effects of ERK1/2 and NF-kB signal pathway on alkaline phosphatase, type Ⅰcol agen, osteocalcin and interleukin-6 expression in osteoblasts in response to mechanical strain, and to explore the regulatory effects of ERK1/2 and NF-kB signal pathway on osteoblast differentiation. <br> METHODS:MC3T3-E1 cells cultured in vitro were separately treated with ERK1/2 pathway specific inhibitor PD098059 and NF-kB pathway inhibitor PDTC for 30 minutes, and subjected to12%elongation for 24 hours. Normal cells and cells along loading 12%mechanical strain for 24 hours were considered as controls. Enzyme linked immunosorbent assay and real-time PCR were utilized to detect alkaline phosphatase activities, type Ⅰcol agen, osteocalcin and interleukin-6 mRNA expression before and after cellloading. <br> RESULTS AND CONCLUSION:Under 12%mechanical strain, alkaline phosphatase, type I col agen, and interleukin-6 expression was regulated by ERK1/2 signal pathway in MC3T3-E1 cells, but osteocalcin gene expression was not affected by ERK1/2 pathway. NF-kB signal pathway inhibitor PDTC significantly suppressed alkaline phosphatase activities in MC3T3-E1 cells under mechanical strain, and inhibited interleukin-6 gene expression. However, type I col agen and osteocalcin gene expression was not affected by NF-kB signal pathway. Results suggested that mechanical strain affected osteogenic differentiation and relevant gene expression in MC3T3-E1 cells by ERK1/2 and NF-kB signal pathway.