耐力训练诱导AMPKα2对鼠骨骼肌pp38和P-MEF2的影响

Effects of Endurance Training Inducing AMPKα2 on the Protein Expression of pp38 and P-MEF2 in Skeletal Muscle of Mice

目的:研究耐力性跑台运动对AMPKα2 3种不同基因型鼠骨骼肌p38、pp38和P-MEF2A蛋白表达的影响,以探讨运动激活MEF2的具体机制。方法:AMPKα2 3种不同基因型鼠各20只,分别分成安静对照组和耐力训练组,每组10只。安静组小鼠不施加任何运动负荷,耐力训练组小鼠进行速度为12m/min,每天1h,每周6天,持续4周的跑台运动。Western blot法测定骨骼肌p38、pp38和核内P-MEF2A蛋白表达。结果:1)4周耐力训练后,AMPKα2 3种基因型鼠pp38蛋白表达均显著提高,并且AMPKα2转基因鼠与野生鼠相比,p38和pp38蛋白表达明显增加,而AMPKα2敲除鼠pp38表达虽然低于野生鼠,但没有显著性差异;2)耐力训练组与安静组相比,AMPKα2 3种基因型鼠骨骼肌核内P-MEF2A蛋白表达均显著增加,并且AMPKα2转基因鼠与野生鼠相比,核内P-MEF2A表达显著增加,而AMPKα2敲除鼠P-MEF2A与野生鼠相比没有显著性差异;3)42只小鼠骨骼肌内pp38与核内P-MEF2A表达量呈显著正相关(R=0.69,P<0.05)。结论:4周耐力训练对AMPKα2 3种不同基因型鼠骨骼肌内p38蛋白表达影响不大,但可以显著促进p38和MEF2A的激活。AMPKα2可能不是惟一激活p38和MEF2A的途径,耐力训练可能通过pp38激活MEF2A。

Objective： The role of AMPKα2 in regulating endurance treadmill exercise induced p38,pp38 and P-MEF2A was investigated to explore the explicit mechanism of activation of MEF2 by exercise. Methods ： Wildtype （WT, n = 20）, AMPKα 2 transgenic （TG, n = 20） and AMPKα2 knockout （KO, n= 20） mice were randomly divided into control group and endurance exercise group by the weight. The control group had not been exerted any exercise load while the exercise group had undertaken one-hour/day treadmill exercise with an intensity of 12 m/rain for 6 days/week with a duration of four weeks, p38, pp38 and P-MEF2A protein expressions were measured by Western Blot. Results ： 1 ） The overall pp38 protein expression of the three types AMPKα2 mice after four-week endurance training significantly increased. In addition,the p38 and pp38 protein expression of AMPKα2 transgenic mice increased obviously compared to the wild-type mice. Although the pp38 protein expression of AMPKα2 knockout mice is lower than the wild-type mice, there is no significant difference at all. 2）After four- week endurance training, P-MEF2A content in the nucleus of skeletal muscle cell among the three kinds of AMPKα2 mice increase significantly compared to the control group and the nucleus P-MEF2A expression of AMPKα2 transgenic mice was significantly higher than the wild-type mice while there was no significant difference between the AMPKα2 knockout mice and the wild-type mice. 3） The phosphorylation activity of p38 and MEF2A in the skeletal muscle of 42 mice are highly positive correlated （R= 0.69, P〈0.05）. Conclusion.. The influence on the expression of p38 protein caused by endurance training for the three types＇ mice is not significant. However, endurance training can greatly promote the phosphorylation activity of p38 and MEF2A. The data also suggests that perhaps AMPKα2 is not the only pathway to activate p38 as well as MEF2A. The phosphorylation activity of p38 is closely related to the phosphorylation of MEF2 A.