Fiber type-specific expression of GLUT4 in human skeletal muscle - Influence of exercise training
Fiber type-specific expression of GLUT4 in human skeletal muscle - Influence of exercise training
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DOI：
10.2337/diabetes.49.7.1092
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发表时间：
2000-07-01
期刊：
影响因子：
7.7
通讯作者：
Richter, EA
中科院分区：
文献类型：
--
作者：
Daugaard, JR;Nielsen, JN;Richter, EA
研究了8名未接受训练的年轻男性受试者骨骼肌GLUT 4的纤维类型特异性表达以及2周低强度训练的影响。从股外侧肌活检样本中解剖出单个肌纤维。基于肌球蛋白重链（MHC）表达，将纤维合并成3组（MHC I、MHC IIA和MHC IIX），并使用SDS-PAGE和免疫学检测来测定15-40个合并纤维的GLUT 4含量。表达MHCI的肌纤维中GLUT 4含量比表达MHCIIA或MHCIIX的肌纤维中GLUT 4含量高约20%（P < 0.05）。在表达MHC IIA或MHC IIX的纤维之间，GLUT 4没有差异。两周的运动训练使膝伸肌的峰值功率输出增加了13%（P < 0.05），柠檬酸合酶和3-羟酰辅酶A脱氢酶的最大活性分别增加了21%和18%，肌肉匀浆中GLUT 4蛋白含量增加了26%。此外，运动训练2周后，在表达MHC I亚型的纤维中观察到GLUT 4增加23%（P < 0.05）。在表达MHC IIA或MHC IIX的纤维中未观察到变化。总之，我们的数据直接表明，GLUT 4在人体骨骼肌中以纤维类型特异性方式表达，尽管纤维类型差异相对较小。此外，低强度运动训练主要招募表达MHC I的纤维增加了这些纤维中的GLUT 4含量，但在表达MHC IIA或MHC IIX的纤维中没有增加，这表明GLUT 4蛋白含量与纤维的活性水平有关，而不是与其纤维类型有关，其由收缩蛋白的表达定义。
The fiber type-specific expression of skeletal muscle GLUT4 and the effect of 2 weeks of low-intensity training were investigated in 8 young untrained male subjects. Single muscle fibers were dissected from a vastus lateralis biopsy sample. Based on myosin heavy chain (MHC) expression, fibers were pooled into 3 groups (MHC I, MHC IIA, and MHC IIX), and the GLUT4 content of 15-40 pooled fibers was determined using SDS-PAGE and immunological detection. The GLUT4 content in pooled muscle fibers expressing MHC I was similar to 20% higher (P < 0.05) than that in muscle fibers expressing MHC IIA or MHC IIX. No difference in GLUT4 could be detected between fibers expressing MHC IIA or MHC IIX. Two weeks of exercise training increased (P < 0.05) the peak power output of the knee extensors by 13%, the maximal activities of citrate synthase and 3-hydroxyacyl-CoA dehydrogenase by 21 and 18%, respectively, and the GLUT4 protein content by 26% in a muscle homogenate. Furthermore, a 23% increase (P < 0.05) in GLUT4 was seen in fibers expressing the MHC I isoform after exercise training for 2 weeks. No change was seen in fibers expressing MHC IIA or MHC IIX. In conclusion, our data directly demonstrate that GLUT4 is expressed in a fiber type-specific manner in human skeletal muscle, although fiber type differences are relatively small. In addition, low-intensity exercise training recruiting primarily fibers expressing MHC I increased GLUT4 content in these fibers but not in fibers expressing MHC IIA or MHC IIX, indicating that GLUT4 protein content is related more to activity level of the fiber than to its fiber type, which is defined by expression of contractile protein.