Koopman René, Zorenc Antoine H G, Gransier Rudy J J, Cameron-Smith David, van Loon Luc J C
Dept. of Human Biology, Maastricht Univ., PO Box 616, 6200 MD Maastricht, The Netherlands.
Am J Physiol Endocrinol Metab. 2006 Jun;290(6):E1245-52. doi: 10.1152/ajpendo.00530.2005. Epub 2006 Jan 24.
To investigate the in vivo effects of resistance exercise on translational control in human skeletal muscle, we determined the phosphorylation of AMP-activated kinase (AMPK), eukaryotic initiation factor 4E-binding protein (4E-BP1), p70/p85-S6 protein kinase (S6K1), and ribosomal S6 protein (S6). Furthermore, we investigated whether changes in the phosphorylation of S6K1 are muscle fiber type specific. Eight male subjects performed a single high-intensity resistance exercise session. Muscle biopsies were collected before and immediately after exercise and after 30 and 120 min of postexercise recovery. The phosphorylation statuses of AMPK, 4E-BP1, S6K1, and S6 were determined by Western blotting with phospho-specific and pan antibodies. To determine fiber type-specific changes in the phosphorylation status of S6K1, immunofluorescence microscopy was applied. AMPK phosphorylation was increased approximately threefold immediately after resistance exercise, whereas 4E-BP1 phosphorylation was reduced to 27 +/- 6% of preexercise values. Phosphorylation of S6K1 at Thr421/Ser424 was increased 2- to 2.5-fold during recovery but did not induce a significant change in S6 phosphorylation. Phosphorylation of S6K1 was more pronounced in the type II vs. type I muscle fibers. Before exercise, phosphorylated S6K1 was predominantly located in the nuclei. After 2 h of postexercise recovery, phospho-S6K1 was primarily located in the cytosol of type II muscle fibers. We conclude that resistance exercise effectively increases the phosphorylation of S6K1 on Thr421/Ser424, which is not associated with a substantial increase in S6 phosphorylation in a fasted state.
为了研究抗阻运动对人体骨骼肌翻译控制的体内效应，我们测定了AMP激活的蛋白激酶（AMPK）、真核起始因子4E结合蛋白（4E-BP1）、p70/p85-S6蛋白激酶（S6K1）和核糖体S6蛋白（S6）的磷酸化水平。此外，我们还研究了S6K1磷酸化的变化是否具有肌肉纤维类型特异性。8名男性受试者进行了一次高强度抗阻运动训练。在运动前、运动后即刻以及运动后恢复30分钟和120分钟时采集肌肉活检样本。通过使用磷酸化特异性抗体和泛抗体的蛋白质免疫印迹法测定AMPK、4E-BP1、S6K1和S6的磷酸化状态。为了确定S6K1磷酸化状态的纤维类型特异性变化，采用了免疫荧光显微镜技术。抗阻运动后即刻，AMPK磷酸化增加了约3倍，而4E-BP1磷酸化降至运动前值的27±6%。在恢复过程中，S6K1在Thr421/Ser424位点的磷酸化增加了2至2.5倍，但未引起S6磷酸化的显著变化。S6K1的磷酸化在II型肌纤维中比I型肌纤维更明显。运动前，磷酸化的S6K1主要位于细胞核中。运动后恢复2小时后，磷酸化的S6K1主要位于II型肌纤维的细胞质中。我们得出结论，抗阻运动有效地增加了S6K1在Thr421/Ser424位点的磷酸化，在禁食状态下，这与S6磷酸化的大幅增加无关。
