Association of the insulin receptor with phospholipase C-gamma (PLCgamma) in 3T3-L1 adipocytes suggests a role for PLCgamma in metabolic signaling by insulin.
Phospholipase C-gamma (PLCgamma) is the isozyme of PLC phosphorylated by multiple tyrosine kinases including epidermal growth factor, platelet-derived growth factor, nerve growth factor receptors, and nonreceptor tyrosine kinases. In this paper, we present evidence for the association of the insulin receptor (IR) with PLCgamma. Precipitation of the IR with glutathione S-transferase fusion proteins derived from PLCgamma and coimmunoprecipitation of the IR and PLCgamma were observed in 3T3-L1 adipocytes. To determine the functional significance of the interaction of PLCgamma and the IR, we used a specific inhibitor of PLC, U73122, or microinjection of SH2 domain glutathione S-transferase fusion proteins derived from PLCgamma to block insulin-stimulated GLUT4 translocation. We demonstrate inhibition of 2-deoxyglucose uptake in isolated primary rat adipocytes and 3T3-L1 adipocytes pretreated with U73122. Antilipolytic effect of insulin in 3T3-L1 adipocytes is unaffected by U73122. U73122 selectively inhibits mitogen-activated protein kinase, leaving the Akt and p70 S6 kinase pathways unperturbed. We conclude that PLCgamma is an active participant in metabolic and perhaps mitogenic signaling by the insulin receptor in 3T3-L1 adipocytes.
Kayali
A G
AG
UCSD/Whittier Diabetes Program, University of California San Diego, La Jolla, California 92093 and the Medical Research Service, Department of Veterans Affairs, Medical Center, San Diego, California 92161, USA.
Eichhorn
J
J
Haruta
T
T
Morris
A J
AJ
Nelson
J G
JG
Vollenweider
P
P
Olefsky
J M
JM
Webster
N J
NJ
D016475:3T3 Cells; D017667:Adipocytes / Q000201:enzymology / Q000378:metabolism*; D000818:Animals; D003847:Deoxyglucose / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D051275:Glucose Transporter Type 4; D007328:Insulin / Q000378:metabolism*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008066:Lipolysis; D008297:Male; D051379:Mice; D008845:Microinjections; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D009124:Muscle Proteins; D051966:Phospholipase C gamma; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011972:Receptor, Insulin / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018909:src Homology Domains
D004791:Enzyme Inhibitors; D004963:Estrenes; D051275:Glucose Transporter Type 4; D007328:Insulin; D007527:Isoenzymes; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D011760:Pyrrolidinones; D011993:Recombinant Fusion Proteins; C495693:Slc2a4 protein, mouse; C495694:Slc2a4 protein, rat; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D003847:Deoxyglucose; D011972:Receptor, Insulin; D010738:Type C Phospholipases; D051966:Phospholipase C gamma