Insulin-stimulated GLUT4 translocation is relevant to the phosphorylation of IRS-1 and the activity of PI3-kinase.
We examined the role of 185-kDa insulin receptor substrate-1 (IRS-1) and phosphatidylinositol 3-kinase (PI3-kinase) in the signaling pathway of insulin-stimulated GLUT4 translocation. We had already developed a novel cell line to detect GLUT4 on the cell surface, directly and sensitively (Kanai, F., Nishioka, Y., Hayashi, H., Kamohara, S., Todaka, M., and Ebina, Y. (1993) J. Biol. Chem. 268, 14523-14526). We stably expressed a mutant insulin receptor in which Tyr972 was replaced with phenylalanine. Insulin-stimulated tyrosyl phosphorylation of IRS-1 and GLUT4 translocation were decreased in cells expressing the mutant receptor, as compared to findings in cells expressing the normal receptor. Wortmannin, an inhibitor of PI3-kinase, inhibits the insulin-stimulated PI3-kinase activity and GLUT4 translocation at 50 nM, but not the NaF-stimulated GLUT4 translocation. These results suggest that the tyrosine phosphorylation of IRS-1 and activation of PI3-kinase may be involved in the signaling pathway of the insulin-stimulated GLUT4 translocation.
Department of Enzyme Genetics, University of Tokushima, Japan.
F
F
Kanai
K
K
Ito
M
M
Todaka
H
H
Hayashi
S
S
Kamohara
K
K
Ishii
T
T
Okada
O
O
Hazeki
M
M
Ui
Y
Y
Ebina
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D016259:Genes, myc; D051275:Glucose Transporter Type 4; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins; D007700:Kinetics; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis / Q000378:metabolism*; D009124:Muscle Proteins; D016297:Mutagenesis, Site-Directed; D019869:Phosphatidylinositol 3-Kinases; D010739:Phospholipase D / Q000037:antagonists & inhibitors; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis; D011972:Receptor, Insulin / Q000096:biosynthesis / Q000378:metabolism; D012969:Sodium Fluoride / Q000494:pharmacology; D014162:Transfection; D000077191:Wortmannin
D000730:Androstadienes; D051275:Glucose Transporter Type 4; C526292:IRS1 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D010750:Phosphoproteins; D016271:Proto-Oncogene Proteins c-myc; C495692:SLC2A4 protein, human; D012969:Sodium Fluoride; D010770:Phosphotransferases; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D011972:Receptor, Insulin; D010739:Phospholipase D; D000077191:Wortmannin