Objective: To analyze the molecular mechanisms of skeletal muscle cells apoptosis induced by heavy-load exercise with Omi as the entry point.
Methods: One hundred and twenty-six adult SD rats were randomly divided into five groups: control group(C), eccentric exercise group (E), simple blocking group (U), DMSO group (D) and exercise block group (EU). In addition to the C group, the other four groups were randomly divided into 0 h after experiment, 12 h after experiment, 24 h after experiment, 48 h after experiment and 72 h after experiment with 6 rats in each group. E and EU group were submitted to a heavy-load exercise on a treadmill down a 16° decline, 16 m/min for 90 minutes. U, D and EU group were one-time intervened with drugs. U and EU groups were intraperitoneally injected with 1.5 μmol/kg ucf-101, D group were intraperitoneally injected with 1.5 μmoL/kg 0.5% DMSO. The rats were sacrificed in batches at different time points after experiment, then the soleus were saved to detect the Caspase-3,-8,-9,-12 activities and protein expressions of Omi and XIAP.
Results: Compared with group C, the mitochondrial distribution and morphology appeared the typical ultrastructure pathological changes, the opening degree of MPTP was increased significantly (P＜0.01) or (P＜0.05), protein expressions of Omi and XIAP were increased significantly (P＜0.01 or P＜0.05), the activities of Caspase-9 and Caspase-3 were increased significantly (P＜0.01 or P＜0.05) in group E. Compared with group C, there was no significant difference in XIAP protein and caspase-9, - 3 activities in group U and Group D. The change trend of XIAP protein and Caspase-9, - 3 activities was the same as those between EU group and E group, but the change range of XIAP protein in EU group was significantly higher than that in E group (P＜0.01), and the change ranges of caspase-9, - 3 activities in EU group were significantly lower than those in E group (P＜0.01).
Conclusion: A single heavy-load exercise can induce changes in the mitochondria morphology and structure in rats, open the high permeability of MPTP, and improve the expression of Omi protein, then through its downstream XIAP-Caspase pathway, start the mitochondrial apoptosis pathway mediated by caspase-9, and finally lead to myocyte apoptosis. The inhibition of Omi can reduce the cell apoptosis level of motor induced skeletal muscle cells.
目的: 以丝氨酸蛋白酶Omi为切入点,探究大负荷运动诱导大鼠骨骼肌细胞凋亡的可能机制。方法: 126只健康雄性SD大鼠随机分为安静对照组(C),离心运动组(E),单纯阻断组(U),二甲基亚砜(DMSO)组(D),运动阻断组(EU)。除C组外,其余4组随机分为干预后0 h组、12 h组、24 h组、48 h组、72 h组,每组6只。E组与EU组大鼠在跑台上进行坡度为-16°,速度为16 m/min,90 min的一次性大负荷运动。U组、D组与EU组进行一次性药物干预,给予U组和EU组大鼠腹腔注射1.5 μmoL/kg Omi特异性抑制剂Ucf-101,同样给予D组大鼠腹腔注射1.5 μmoL/kg的0.5% DMSO,于实验后不同时间点分批取比目鱼肌,检测其Caspase-3,-8,-9,-12的活性以及Omi和X染色体连锁的凋亡抑制蛋白(XIAP)的表达。结果: 与C组相比,E组骨骼肌线粒体形态结构发生典型的病理改变,骨骼肌线粒体膜通透性转换孔(MPTP)开放程度明显增加(P＜0.01)或(P＜0.05),同时骨骼肌Omi、XIAP蛋白表达均明显增加(P＜0.01或P＜0.05),Caspase-9,-3活性也均明显增加(P＜0.01或P＜0.05)。与C组相比,U组和D组XIAP蛋白以及Caspase-9,-3活性均无显著差异。EU组XIAP蛋白以及Caspase-9,-3活性变化趋势均与E组基本一致,但XIAP蛋白变化幅度明显高于E组(P＜0.01),Caspase-9,-3活性变化幅度明显低于E组(P＜0.01)。结论: 大负荷运动可以诱导大鼠骨骼肌线粒体形态结构改变,使MPTP高通透性开放,Omi蛋白表达上调,进而通过其下游的XIAP-Caspase途径,启动依赖Caspase-9介导线粒体凋亡途径,最终导致肌细胞发生凋亡,而抑制Omi可降低运动诱导骨骼肌细胞的凋亡水平。.
Keywords: Omi; Ucf-101; XIAP; cell apoptosis; exercise; rat; skeletal muscle.