In L6 myotubes insulin stimulates glucose transport through the translocation of glucose transporters GLUT1, GLUT3 and GLUT4 from intracellular stores to the plasma membrane. An intact actin network and phosphatidylinositol 3-kinase activity are required for this process. Glucose transport is also stimulated by the mitochondrial ATP-production uncoupler dinitrophenol. We show here that, in serum-depleted myotubes, dinitrophenol induced translocation of GLUT1 and GLUT4, but not GLUT3. This response was not affected by inhibiting phosphatidylinositol 3-kinase or disassembling the actin network. Insulin, but not dinitrophenol, caused tyrosine phosphorylation of several polypeptides, including the insulin-receptor substrate-1 and mitogen-activated protein kinase. Similarly, insulin, but not dinitrophenol, caused actin reorganization, which was inhibited by wortmannin. We conclude that insulin and dinitrophenol stimulate glucose transport by different mechanisms.
Phosphatidylinositol 3-kinase and the actin network are not required for the stimulation of glucose transport caused by mitochondrial uncoupling: comparison with insulin action
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T Tsakiridis, M Vranic, A Klip; Phosphatidylinositol 3-kinase and the actin network are not required for the stimulation of glucose transport caused by mitochondrial uncoupling: comparison with insulin action. Biochem J 1 July 1995; 309 (1): 1–5. doi: https://doi.org/10.1042/bj3090001
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