一次大强度运动对大鼠骨骼肌泛素蛋白酶体途径基因表达及蛋白质降解的影响

目的:观察1次大强度运动后骨骼肌泛素蛋白酶体途径组成成分基因表达的变化,探讨该途径在运动后骨骼肌蛋白质降解中的作用。方法:36只雄性SD大鼠,体重190～220 g,跑台运动适应3天,休息1天,取6只为安静对照,其余大鼠进行1次1小时跑台运动(25 m/min,5%坡度)。运动0.5小时即刻、运动1小时即刻、运动后1小时、运动后2小时、运动后6小时,分别选6只大鼠取腓肠肌,用Real-Time PCR法测定泛素、MuRF1、MAFbx mRNA含量,用Western Blot法检测泛素化蛋白含量,用高效液相色谱法检测肌肉3-MH含量。结果:运动0.5、1小时即刻至运动后6小时,腓肠肌泛素mRNA含量与安静时比较无显著性差异(P>0.05)。1小时运动后1、2和6小时,腓肠肌MAFbx和MuRF1 mRNA含量较安静时显著升高(P<0.01,P<0.05)。1小时运动后6小时,腓肠肌泛素化蛋白含量显著高于安静时(P<0.01)。运动0.5小时、1小时即刻和运动后6小时,腓肠肌3-MH含量显著高于安静(P<0.01)。结论:1次大强度运动后,骨骼肌泛素蛋白酶体途径基因表达升高,骨骼肌收缩蛋白降解增加。

Effects of Acute Exercise on the Genetic Expression of Ubiquitin-Proteasome Pathway and Protein Degradation in Rat Skeletal Muscle

Objective To study the role of ubiquitin(UB)-proteasome pathway(UPP) of skeletal muscle on the protein degradation after an acute exercise.Methods Male SD rats(n=36) were adapted to treadmill exercise for 3 days.After 1-day rest,6 rats were used as quiet control group,and the remaining rats ran on the treadmill for 1 hour(25m/min,5% slope).Every 6 rats were killed at 0.5 h and 1 h immediate after exercise,and at 1 h,2 h,6 h after exercise,and the changes in the genetic expression of Ub,MuRF1,MAFbx mRNA,ubiquitin-conjugated protein level and 3-MH were assayed with Real-Time PCR,Western Blot,and high-efficiency liquid chromatography,respectively.Results(1)There was no significant difference in the content of Ub mRNA before and after exercise.(2)Contents of MAFbx and MuRF1 mRNA were higher after 1hr exercise than at rest(P < 0.01,P < 0.05,respectively).(3)Ubiquitinated protein level was higher at 6 h after 1 h exercise than at rest(P < 0.05).(4)3-MH content was higher 0.5 h and 1 h immediately after exercise and at 6h post-exercise than at rest.Conclusion Both genetic expressions of ubiquitin-proteasome pathway and degree of contractile protein degradation of skeletal muscle were enhanced after one bout of high-intensity exercise.