机械牵拉通过抑制MSTN表达促进骨骼肌卫星细胞增殖的研究

Passive movement as a means of prevention and treatment of denervated skeletal muscle atrophy is widely used, but because of its mechanism is not clear, its clinical efficacy is limited. Study on its mechanism is of great theoretical and clinical value. Currently it is widely accepted that number reduction or depletion of muscle satellite cells after denervation is the primary cause of denervated skeletal muscle atrophy. Therefore, improving the proliferation ability of muscle satellite cells is the key in prevention and treatment of denervated skeletal muscle atrophy. Myostatin (MSTN) is a key factor in leading to denervated skeletal muscle atrophy, which inhibits the proliferation of muscle satellite cells. Accordingly, we hypothesize that mechanical stretch promotes the proliferation of muscle satellite cells through inhibiting MSTN expression, which may be the main way by which passive movement prevents denervated skeletal muscle atrophy. The project will take the primary skeletal muscle satellite cells as research object, study mechanical stretch regulating MSTN expression through Integrin-FAK-MAPK/ERK pathway to promote the proliferation of muscle satellite cells, using cell and molecular biology technology and related antagonists, to reveal the mechanism by which mechanical stretch promotes the proliferation of muscle satellite cells. The project will also verify the synergistic effect of mechanical stretch and MSTN inhibitor on the proliferation of muscle satellite cells. This study will provide theoretical basis and guiding suggestions for passive movement preventing denervated skeletal muscle atrophy.

被动运动作为防治失神经骨骼肌萎缩手段被广泛应用，但确切机制不明，临床疗效有限，其机制的研究有重要的理论与临床价值。失神经支配后肌卫星细胞数量的减少或耗竭是导致肌萎缩的主要原因，因此改善肌卫星细胞增殖能力是防治失神经肌萎缩的关键。Myostatin（MSTN）是导致失神经肌萎缩的关键因子，可抑制肌卫星细胞增殖。我们前期研究发现，中强度抗阻训练可有效抑制MSTN表达。据此我们推测被动运动引起机械牵拉通过抑制MSTN表达促进肌卫星细胞增殖可能是被动运动防治失神经肌萎缩的主要途径。本项目将以原代肌卫星细胞为研究对象，利用细胞与分子生物学技术及相关阻断剂，研究机械牵拉通过Integrin-FAK-MAPK/ERK途径调控MSTN表达促进肌卫星细胞增殖，揭示机械牵拉促进肌卫星细胞增殖的新机制，并验证机械牵拉与MSTN抑制剂对肌卫星细胞增殖的协同作用，为被动运动防治失神经肌萎缩提供理论基础和指导性建议。

骨骼肌不仅是收缩器官，作为内分泌器官还分泌多种细胞因子调控其他器官的功能。骨骼肌一旦发生萎缩，将引发多种严重的并发症。MSTN是骨骼肌关键负调控因子，敲出 MSTN 基因动物出现“双肌”症状。本项目旨在探讨机械牵拉能否通过抑制MSTN表达促进骨骼肌卫星细胞增殖，进而防止肌萎缩的发生。本课题首先采用三种不同的抗阻力运动，从生理、生化、形态学、基因和蛋白等不同层面研究了机械牵拉刺激对促进正常大鼠骨骼肌肥大和抑制绝经期肌萎缩的效果及其分子机制，并在体验证了MSTN是抗阻力运动改善肌萎缩的关键分子。然后以C2C12细胞（骨骼肌卫星细胞的永生化细胞）为实验对象，研究不同参数的机械牵拉力对成肌细胞增殖和 MSTN蛋白表达的影响，明确了机械牵拉与 MSTN 表达之间关系，确定了2000 μstrain的机械牵拉力是可有效抑制MSTN 表达和促进成肌细胞增殖的机械牵拉参数；验证了机械牵拉能够通过抑制MSTN 的表达促进成肌细胞增殖的假设，明确了MSTN 是机械牵拉促进成肌细胞增殖的关键中介分子，并揭示Integrin-FAK-MAPK/ERK 信号通路是机械牵拉调控MSTN表达的上游信号通路，进而完善了机械牵拉促进成肌细胞增殖的信号网络。本项目的结论为运动改善骨骼肌的状态和功能提供实验学依据，以及为临床治疗肌萎缩提供新的靶分子。