Abstract: Objective To explore the role of cathepsin K (CTSK) regulated by mir-30a-wnt/β-catenin signaling pathway in cementogenic differentiation of periodontal ligament stem cells (PDLSCs). Methods Human PDLSCs isolated by limiting dilution culture were induced by enamel matrix protein derivative (EMD) for differentiation into cementoblast-like cells. MicroRNA chip technique was employed to screen the differentially expressed microRNAs in the cells during induced differentiation. The effect of inhibiting miR-30a on CTSK expression in the induced cells was examined using RT-PCR and Western blotting. Ceramic scaffolds coated with PDLSCs treated with EMD and transfected with the miR-30a inhibitor or a lentiviral vector for CTSK overexpression were prepared and implanted subcutaneously in nude mice, and 8 weeks later the cellular expressions of cementoblast markers CAP and CEMP-1 were detected with immunohistochemistry to verify whether CTSK participate in cementogenic differentiation of PDLSCs. The role of wnt signaling pathway in miR-30a-mediated regulation of CTSK expression was explored by examining CTSK protein expressions after blocking wnt signaling in PDLSCs. Results In PDLSCs with EMD-induced differentiation into cementoblast-like cells, multiple microRNAs exhibited differential expressions; and among them, miR-30a was specifically and significantly up-regulated (P<0.05). Up-regulation of miR-30a obviously increased the expression of CTSK (P<0.05) and promoted PDLSCs to form cementum-like tissues with high expressions of CAP and CEMP-1. The regulatory effect of miR-30a on CTSK expression was obviously attenuated after inhibiting wnt/β-catenin signaling pathway. Conclusion EMD induces cementogenic differentiation of PDLSCs possibly by up-regulating the expression of miR-30a, which further activates the wnt/β-catenin signaling pathway to enhance the expression of CTSK.

Key words: periodontal ligament stem cells, cathepsin K, cementogenic differentiation, microRNA, wnt signaling pathway