运动性骨骼肌损伤大鼠膜修复蛋白dysferlin的作用机制

Mechanism by which dysferlin promotes repair of exercise-induced skeletal muscie injury in rats

背景:目前关于dysferlin的研究多集中在肌肉疾病(如肌营养不良)上,而针对运动后肌损伤发生后细胞膜的修复与dysferlin的关系鲜有研究。目的:观察急性离心运动后大鼠腓肠肌细胞膜通透性及膜修复蛋白dysferlin及calpain3表达变化,为深化肌组织再生分子机制及肌肉疾病的运动治疗提供理论参考。方法:将32只大鼠随机分为对照组、运动后24,48,72 h组。采用免疫组织化学染色、Western blot及qRT-PCR等方法检测大鼠腓肠肌细胞膜完整性和dysferlin,calpain3蛋白及基因表达。结果与结论:与对照组相比,运动后24 h组血清肌酸激酶活性、Calpain3 mRNA,dysferlin蛋白表达及骨骼肌细胞膜损伤程度均增高(P<0.05或P<0.01);运动后24,48 h组大鼠dysferlin mRNA表达量高于运动后72 h组(P<0.05)。结果说明,离心运动后24 h,骨骼肌细胞膜损伤最为严重,人体通过Ca^(2+)内流,激活了细胞内钙激活酶calpain3基因表达,进而通过促进膜特异性修复蛋白dysferlin表达修复受损的骨骼肌细胞膜。

BACKGROUND： Numerous studies concerning dysferlin focus on muscle diseases（such as muscular dystrophy）, but the relationship between membrane repair after exercise-induced muscle damage and dysferlin is little reported. OBJECTIVE： To observe the cell membrane permeability and expression levels of dysferlin and calpain3 in the rat gastrocnemius after acute eccentric exercise, so as to provide an theoretical reference for exploring the molecular mechanism of muscle regeneration and the exercise therapy of muscular diseases. METHODS： Thirty-two Sprague-Dawley rats were randomly divided into four groups including control, 24, 48 and 72 hours post exercise groups. The membrane permeability and expression levels of dysferlin and calpain3 were determined by immunohistochemistry, western blot assay and qRT-PCR. RESULTS AND CONCLUSION： The activity of serum creatine kinase, and expression levels of calpain3 mRNA and dysferlin protein, as well as membrane permeability at 24 hours post exercise were significantly greater than those in the control group（P 0.05 or 0.01）. The expression level of dysferlin mRNA at 24 and 48 hours post exercise was significantly higher than that at 72 hours post exercise（P 0.05）. Therefore, the damage to the skeletal muscle cell membrane was the most severe at 24 hours after eccentric exercise. Due to Ca-（2＋） influx, expression of calpain3 mRNA was activated, and then the damaged cell membrane was repaired by increasing the expression of dysferlin.