Objective: This study investigated the role and mechanism of calcineurin (CaN)-nuclear factor of activated T cells (NFAT) pathway in the myoblast apoptosis induced by cyclic tensile strain.
Methods: Myoblasts were cultured using an in vitro-mechanical stimulation model and imposed with tension for different hours with a multi-channel cell stress loading system. Cyclosporine (CsA) was used as CaN inhibitor to clarify the role of CaN in the apoptosis induced by cyclic stress. Hochest 33258 staining and flow cytometry detection were performed to detect the apoptotic cells. Real-time polymerase chain reaction was conducted to detect the mRNA expression of CaN and NFAT. Protein levels of NFAT3 were evaluated by Western blot.
Results: The apoptosis rate increased with the extension of loading time. The mRNA expression of the CaN subunits, CnA and CnB, and the protein levels of NFAT3 also increased. When the myoblasts were incubated with CsA, the apoptosis rate decreased, the mRNA expression of CnA and NFAT3 significantly decreased, and the NFAT3 protein expression levels became significantly lower than those of the groups without CsA.
Conclusion: Continuous cyclic tensile stress can induce myoblast apoptosis. The CaN-NFAT signaling pathway may be involved in the cyclic stretch-induced apoptosis of myoblasts.
目的: 探讨钙调神经磷酸酶（CaN）-T细胞核因子（NFAT）信号通路在应力介导的成肌细胞凋亡中的作用。
方法: 构建成肌细胞体外培养—力学刺激模型，利用多通道应力加载系统对细胞加载不同时间的周期性张应力，加入CaN的特异性抑制剂环孢素（CsA）作为对比。采用Hoechst 33258染色法和流式细胞术检测成肌细胞凋亡情况，实时聚合酶链式反应检测CaN和NFAT mRNA的表达情况，蛋白质印迹法检测NFAT3的蛋白含量。
结果: 随加力时间的延长，细胞凋亡逐渐增加，CaN亚基CnA、CnB及NFAT3的mRNA表达及NFAT3蛋白含量逐渐升高；加入CsA后，细胞凋亡减少，CnA、NFAT3的mRNA表达及NFAT3的蛋白含量明显减少。
结论: 周期性张应力可以诱导成肌细胞发生凋亡；CaN-NFAT信号通路可能参与了周期性张应力诱导的成肌细胞凋亡。