title: Phosphatidylinositol 3-kinase and the actin network are not required for the stimulation of glucose transport caused by mitochondrial uncoupling: comparison with insulin action.
abstract: 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.
authors.affiliation: Division of Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: T
authors.initials: T
authors.lastname: Tsakiridis
authors.forename: M
authors.initials: M
authors.lastname: Vranic
authors.forename: A
authors.initials: A
authors.lastname: Klip
mesh_terms: D000199:Actins / Q000378:metabolism*; D001692:Biological Transport; D002478:Cells, Cultured; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology*; D008931:Mitochondria, Muscle / Q000187:drug effects* / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000187:drug effects / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*
chemical_list: D000199:Actins; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D005947:Glucose