Insulin stimulates phosphatidylinositol 3-kinase activity in rat neuronal primary cultures.
We investigated the effect of insulin on phosphatidylinositol (PtdIns) 3-kinase (PtdIns 3-kinase) activity in neuronal cultures to determine if this enzyme is involved with the neurotrophic actions of insulin. Insulin caused a concentration-dependent increase in PtdIns 3-kinase activity in anti-phosphotyrosine immunoprecipitates. The kinase activity was able to phosphorylate PtdIns, PtdIns 4-phosphate, and PtdIns 4,5-bisphosphate. In intact neurons, a 10-min 1 mM insulin treatment in the presence of [32P]orthophosphate increased the levels of both 3-[32P]PtdIns phosphate and 3,4-[32P]PtdIns bisphosphate by 55 and 193%, respectively. This increase was associated with an increase in neurite outgrowth mediated by insulin. Our results indicate that insulin treatment of neuronal cells in primary culture increases PtdIns 3-kinase activity and the formation of the unique D-3-phosphorylated phosphoinositides, suggesting that growth factor-mediated neuronal growth may include the formation of novel phosphoinositide 3-phosphate phospholipids.
Department of Pharmacology, College of Medicine, University of Florida, Gainesville 32610-0627.
R A
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Patel
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P
Kurian
M K
MK
Raizada
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FT
Crews
D000818:Animals; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D007150:Immunohistochemistry; D007328:Insulin / Q000494:pharmacology*; D009474:Neurons / Q000201:enzymology*; D019869:Phosphatidylinositol 3-Kinases; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism*; D011233:Precipitin Tests; D051381:Rats
D007328:Insulin; D010770:Phosphotransferases; D019869:Phosphatidylinositol 3-Kinases