Insulin activates phospholipase C-gamma1 via a PI-3 kinase dependent mechanism in 3T3-L1 adipocytes.
Previously we have shown that the insulin receptor and phospholipase C-gamma1 physically interact in the 3T3-L1 adipocyte cell line. In this study, we investigated the ability of insulin and PDGF to stimulate PLC-gamma1 enzyme activity as measured by PI-(4,5)P(2) hydrolysis. Both insulin and PDGF caused a rapid (<1 min) increase in PLC activity associated with the respective receptor. PDGF treatment resulted in a higher and more sustained stimulation of PLC-gamma1 activity compared to insulin (0.95 pmol/min/mg vs 0.68 pmol/min/mg). Furthermore, insulin and PDGF promoted increases in total cellular DAG, one of the products of PI-(4,5)P(2) hydrolysis. Insulin-stimulated PLC activity appears to be downstream of PI-3Kinase as the DAG increase was partially blocked by Wortmannin and addition of PI-(3,4,5)P(3) activated PLC-gamma1 in vitro. Inhibition of PLC using U73122 or an inhibitory peptide caused a decrease in insulin-stimulated 2-deoxyglucose transport and GLUT4 translocation that was rescued by the addition of OAG, a cell-permeable synthetic DAG.
Eichhorn
J
J
Medical Research Service, San Diego Veterans Affairs Healthcare System, San Diego, California 92161, USA.
Kayali
A G
AG
Austin
D A
DA
Webster
N J
NJ
D016475:3T3 Cells; D017667:Adipocytes / Q000187:drug effects* / Q000201:enzymology* / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D004075:Diglycerides / Q000096:biosynthesis / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004963:Estrenes / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D007328:Insulin / Q000494:pharmacology*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051379:Mice; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D009124:Muscle Proteins; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D051966:Phospholipase C gamma; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism*
D004075:Diglycerides; D004963:Estrenes; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D007328:Insulin; D007527:Isoenzymes; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D010982:Platelet-Derived Growth Factor; D011760:Pyrrolidinones; C495693:Slc2a4 protein, mouse; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D019869:Phosphatidylinositol 3-Kinases; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; D005947:Glucose