MgCl(2) promotes mouse mesenchymal stem cell osteogenic differentiation by activating the p38/Osx/Runx2 signaling pathway

Magnesium, an important inorganic mineral component in bones, enhances osteoblast adhesion and osteogenic gene expression. Mg(2+)-containing hydroxyapatite promotes mouse mesenchymal stem cell (MMSC) osteogenic differentiation. In the present study, MMSCs were cultured in media containing different concentrations of MgCl(2) (0 and 20 mM) for different time periods. Western blotting and reverse transcription-quantitative PCR were performed to determine the expression levels of phosphorylated (p)-p38 mitogen-activated protein kinase (MAPK), the osteoblast-specific transcription factor Osterix (Osx), runt-related transcription factor 2 (Runx2), and p38 downstream genes, such as 27 kDa heat shock protein (hsp27), activating transcription factor 4 (Atf4), myocyte enhancer factor 2C (Mef2c) and CCAAT/enhancer-binding protein homologous protein (Ddit3). The facilitatory effect of MgCl(2) on MMSC osteogenic differentiation was assessed via Alizarin Red staining. The results suggested that MgCl(2) increased p38 phosphorylation compared with the control group. Downstream genes of the p38 signaling pathway, including Osx and Runx2, as well as several osteogenesis-associated downstream target genes, including Hsp27, Atf4, Ddit3 and Mef2c, were significantly upregulated in the Mg(2+)-treated group compared with the control group. The increased osteogenic differentiation in the Mg(2+)-treated group was significantly attenuated in MMSCs treated with SB203580, a specific inhibitor of the p38 signaling pathway. The results suggested that appropriate concentrations of MgCl(2) promoted MMSC osteogenic differentiation via regulation of the p38/Osx/Runx2 signaling pathway.