Mascher H, Andersson H, Nilsson P-A, Ekblom B, Blomstrand E
Astrand Laboratory, Swedish School of Health and Sport Sciences, Stockholm, Sweden.
Acta Physiol (Oxf). 2007 Sep;191(1):67-75. doi: 10.1111/j.1748-1716.2007.01712.x. Epub 2007 May 3.
Exercise induced alterations in the rate of muscle protein synthesis may be related to activity changes in signalling pathways involved in protein synthesis. The aim of the present study was to investigate whether such changes in enzyme phosphorylation occur after endurance exercise.
Six male subjects performed ergometer cycling exercise for 1 h at 75% of the maximal oxygen uptake. Muscle biopsy samples from the vastus lateralis were taken before, immediately after, 30 min, 1 h, 2 h and 3 h after exercise for the determination of protein kinase B (PKB/Akt), mammalian target of rapamycin (mTOR), glycogen synthase 3 kinase (GSK-3), p70S6 kinase (p70(S6k)) and eukaryotic elongation factor 2 (eEF2) phosphorylation.
The phosphorylation of Akt was unchanged directly after exercise, but two- to fourfold increased 1 and 2 h after the exercise, whereas GSK-3alpha and beta phosphorylation were two- to fourfold elevated throughout most of the 3-h recovery period. Phosphorylation of mTOR was elevated threefold directly after, 30 min and 2 h after exercise and eEF2 phosphorylation was decreased by 35-75% from 30 min to 3 h-recovery. Exercise led to a five- to eightfold increase in Ser(424)/Thr(421) phosphorylation of p70(S6k) up to 30 min after exercise, but no change in Thr(389) phosphorylation.
The marked decrease in eEF2 phosphorylation suggests an activation of translation elongation and possibly protein synthesis in the recovery period after sustained endurance exercise. The lack of p70(S6k) activation suggests that translation initiation is activated via alternative pathways, possibly via the activation of eukaryotic initiating factor 2B.
运动引起的肌肉蛋白质合成速率变化可能与蛋白质合成相关信号通路的活性改变有关。本研究的目的是调查耐力运动后是否会发生此类酶磷酸化变化。
6名男性受试者以最大摄氧量的75%进行了1小时的测力计骑行运动。在运动前、运动后即刻、运动后30分钟、1小时、2小时和3小时采集股外侧肌的肌肉活检样本，用于测定蛋白激酶B（PKB/Akt）、雷帕霉素哺乳动物靶点（mTOR）、糖原合酶3激酶（GSK-3）、p70S6激酶（p70(S6k)）和真核延伸因子2（eEF2）的磷酸化水平。
运动后即刻Akt的磷酸化水平未发生变化，但在运动后1小时和2小时增加了2至4倍，而在整个3小时的恢复期大部分时间内，GSK-3α和β的磷酸化水平升高了2至4倍。运动后即刻、30分钟和2小时mTOR的磷酸化水平升高了3倍，从运动后30分钟到3小时恢复期，eEF2的磷酸化水平降低了35%至75%。运动导致运动后30分钟内p70(S6k)的Ser(424)/Thr(421)磷酸化增加了5至8倍，但Thr(389)磷酸化没有变化。
eEF2磷酸化的显著降低表明在持续耐力运动后的恢复期翻译延伸以及可能的蛋白质合成被激活。p70(S6k)未被激活表明翻译起始通过替代途径被激活，可能是通过真核起始因子2B的激活。
