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.
目的: 探讨牙周膜干细胞（PDLSC）成牙骨质向分化过程中mir-30a-wnt/β-catenin信号轴调控组织蛋白酶K（CTSK）表达的功能作用。
方法: 极限稀释法分离培养PDLSC，釉基质蛋白衍生物（EMD）诱导细胞成牙骨质向分化。在细胞分化过程中，通过microRNA芯片筛选差异表达的microRNA。首先，给予不同分组细胞EMD诱导和/或抑制microRNA表达等处理，无干预组细胞作为对照。利用qPCR和Western blot技术首先验证差异表达的microRNA是否能够调控CTSK的表达。之后，将细胞膜片复合陶瓷支架材料植入裸鼠皮下，利用免疫组织化学方法观察成牙骨质细胞标记蛋白CAP和CEMP-1的表达变化，明确受microRNA调控的CTSK表达变化是否参与了PDLSC成牙骨质分化。在此基础上，从蛋白学水平观察wnt信号通路在microRNA调节CTSK表达过程中是否发挥了相应功效。
结果: EMD诱导PDLSC成牙骨质向分化过程中，多种microRNA表达发生变化，其中miR-30a表达出现特异性上调（P＜0.05）。表达上调的miR-30a进一步调节CTSK的表达（P＜0.05），促进PDLSC异位形成类牙骨质样结构，高表达成牙骨质细胞标记蛋白CAP和CEMP-1。抑制wnt/β-catenin信号通路，miR-30a对CTSK的表达调控作用出现相应减弱。
结论: EMD可能通过上调miR-30a的表达激活wnt/β-catenin信号通路从而经mir-30a-wnt/β-catenin信号轴调控CTSK诱导PDLSC向成牙骨质细胞方向分化。
Keywords: cathepsin K; cementogenic differentiation; microRNA; periodontal ligament stem cells; wnt signaling pathway.