Insulin Activates Phospholipase C-γ1 via a PI-3 Kinase Dependent Mechanism in 3T3-L1 Adipocytes

• Published in: Biochemical and biophysical research communications Vol. 282; no. 2; pp. 615 - 620
• Main Authors: Eichhorn, Jens, Kayali, Ayse G., Austin, Darrell A., Webster, Nicholas J.G.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 30.03.2001
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.2001.4616

Previously we have shown that the insulin receptor and phospholipase C-γ1 physically interact in the 3T3-L1 adipocyte cell line. In this study, we investigated the ability of insulin and PDGF to stimulate PLC-γ1 enzyme activity as measured by PI-(4,5)P2 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-γ1 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)P2 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)P3 activated PLC-γ1 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.