Dissociation of pp70 ribosomal protein S6 kinase from insulin-stimulated glucose transport in 3T3-L1 adipocytes.
The metabolic and mitogenic actions of insulin have been proposed to be mediated by cellular serine/threonine kinases such as the ribosomal protein S6 kinases pp70-S6 (pp70-S6 kinase) and pp90rsk and the erk-encoded mitogen-activated protein kinases (pp42mapk and pp44mapk). Rapamycin completely blocked activation of pp70-S6 kinase by insulin in 3T3-L1 adipocytes, but did not inhibit insulin-stimulated glucose transport, translocation of GLUT4 to the cell surface, or activation of pp90rsk or pp44mapk by insulin. Concordant with the inhibition of kinase activity, rapamycin prevented the insulin-induced decrease in mobility of pp70-S6 kinase visualized by SDS-polyacrylamide gel electrophoresis, reflecting a reduction in the hormone-stimulated phosphorylation of the enzyme. The structurally related macrolide, FK506, had no effect on pp70-S6 kinase or hexose uptake. These data demonstrate that rapamycin blocks insulin activation of pp70-S6 kinase in 3T3-L1 adipocytes and that pp70-S6 kinase is not required in the signaling pathway leading to insulin-stimulated glucose transport.
Fingar
D C
DC
Department of Cellular and Molecular Physiology, Harvard Medical School, Boston, Massachusetts 02115.
Hausdorff
S F
SF
Blenis
J
J
Birnbaum
M J
MJ
D016475:3T3 Cells; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D005947:Glucose / Q000378:metabolism*; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D051379:Mice; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D011090:Polyenes / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D019893:Ribosomal Protein S6 Kinases; D020123:Sirolimus; D016559:Tacrolimus / Q000494:pharmacology
D007328:Insulin; D009004:Monosaccharide Transport Proteins; D011090:Polyenes; D017346:Protein Serine-Threonine Kinases; D019893:Ribosomal Protein S6 Kinases; D005947:Glucose; D020123:Sirolimus; D016559:Tacrolimus