Calcitonin promotes osteogenic differentiation through CREB-mediated transcriptional upregulation of osteopontin in human periodontal ligament stem cells.

Osteogenic differentiation of human periodontal ligament stem cells (PDLSCs) facilitates the neogenesis of alveolar bone and contribute to the alveolar bone repair. Calcitonin (CT) has been reported to promote osteogenic differentiation in osteoblast, but its effects and mechanism on human PDLSCs remain obscure. In this study, alizarin red staining and western blot were used to evaluate the osteogenic differentiation and the expression level of cAMP-response element-binding protein (CREB), phosphorylated CREB (pCREB), and osteopontin (OPN) in human PDLSCs. The transcriptional regulation of CREB on OPN expression was detected by chromatin immunoprecipitation (ChIP) and luciferase reporter assays. In human PDLSCs, CT overexpression significantly enhanced the expression of OPN and strengthened the mineralization, and upregulated the expression level of CREB and pCREB. The mineralized deposit and expression of OPN promoted by CT were reduced by inhibiting the expression or activity of CREB. CREB could directly bind to OPN promoter and transcriptionally regulate OPN expression. Inhibiting the expression of OPN reversed the cell osteogenic differentiation promoted by CREB. Our study supports that CT can promote osteogenic differentiation of human PDLSCs through enhancing the expression and phosphorylation of CREB, subsequently transcriptionally regulating OPN expressions.