Guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) stimulation of GLUT4 translocation is tyrosine kinase-dependent.
Guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) treatment of permeabilized adipocytes results in GLUT4 translocation similar to that elicited by insulin treatment. However, although the selective phosphatidylinositol 3-kinase inhibitor, wortmannin, completely prevented insulin-stimulated GLUT4 translocation, it was without effect on GTPgammaS-stimulated GLUT4 translocation. In addition, insulin was an effective stimulant, whereas GTPgammaS was a very weak activator of the downstream Akt serine/threonine kinase. Consistent with an Akt-independent mechanism, guanosine 5'-O-2-(thio)diphosphate inhibited insulin-stimulated GLUT4 translocation without any effect on the Akt kinase. Surprisingly, two functionally distinct tyrosine kinase inhibitors, genistein and herbimycin A, as well as microinjection of a monoclonal phosphotyrosine specific antibody, inhibited both GTPgammaS- and insulin-stimulated GLUT4 translocation. Phosphotyrosine immunoblotting and specific immunoprecipitation demonstrated that GTPgammaS did not elicit tyrosine phosphorylation of insulin receptor or insulin receptor substrate-1. In contrast to insulin, proteins in the 120-130-kDa and 55-75-kDa range were tyrosine-phosphorylated following GTPgammaS stimulation. Several of these proteins were identified and include protein-tyrosine kinase 2 (also known as CAKbeta, RAFTK, and CADTK), pp125 focal adhesion tyrosine kinase, pp130 Crk-associated substrate, paxillin, and Cbl. These data demonstrate that the GTPgammaS-stimulated GLUT4 translocation utilizes a novel tyrosine kinase pathway that is independent of both the phosphatidylinositol 3-kinase and the Akt kinase.
Elmendorf
J S
JS
Department of Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242, USA.
Chen
D
D
Pessin
J E
JE
D016475:3T3 Cells; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D016227:Benzoquinones; D001692:Biological Transport; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D051275:Glucose Transporter Type 4; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology; D047029:Lactams, Macrocyclic; D051379:Mice; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009124:Muscle Proteins; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011809:Quinones / Q000494:pharmacology; D017828:Rifabutin / Q000031:analogs & derivatives; D000077191:Wortmannin
D000730:Androstadienes; D016227:Benzoquinones; D004791:Enzyme Inhibitors; D051275:Glucose Transporter Type 4; D007328:Insulin; D047029:Lactams, Macrocyclic; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D011809:Quinones; C495693:Slc2a4 protein, mouse; D017828:Rifabutin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C020754:herbimycin; D019833:Genistein; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D000077191:Wortmannin