Cooperative effects of ethanol and protein kinase C activators on phospholipase-D-mediated hydrolysis of phosphatidylethanolamine in NIH 3T3 fibroblasts.
In a previous study, ethanol was shown to enhance the stimulatory effect of phorbol 12-myristate 13-acetate (PMA), a prominent activator of protein kinase C (PKC), on phospholipase-D (PLD)-mediated hydrolysis of phosphatidylethanolamine (PtdEtn) in NIH 3T3 fibroblasts (Kiss et al. (1991) Eur. J. Biochem. 197, 785-790). Here, the mechanism and possible significance of ethanol-stimulated PtdEtn hydrolysis was further studied. In [14C]ethanolamine-labeled NIH 3T3 fibroblasts, 10 mM ethanol enhanced PMA-induced hydrolysis of PtdEtn 1.5-2.0-fold during a 2.5-15-min incubation period. Other alcohols, including glycerol, methanol, and 1-propanol, also enhanced PMA-induced PtdEtn hydrolysis. Of the other PLD activators tested, ethanol potentiated the PKC-dependent stimulatory effect of bombesin but failed to alter the apparently PKC-independent stimulatory effect of serum. Pretreatment of [14C]ethanolamine-labeled fibroblasts with 200 mM ethanol for 20 min resulted in increased (approx. 2-fold) hydrolysis of [14C]PtdEtn in isolated membranes. In membranes from ethanol-treated, but not from untreated, cells, PMA further enhanced (approx. 1.5-fold) the production of [14C]ethanolamine. Ethanol exerted none of the above stimulatory effects on phosphatidylcholine hydrolysis. These results suggest that the specific stimulatory action of ethanol on PLD-mediated PtdEtn hydrolysis can occur in vivo and may involve increased binding of a regulatory PKC-isoform to membranes.
Kiss
Z
Z
Hormel Institute, University of Minnesota, Austin 55912.
D016475:3T3 Cells / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D001839:Bombesin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D000431:Ethanol / Q000494:pharmacology*; D051379:Mice; D010712:Phosphatidic Acids / Q000096:biosynthesis; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D000431:Ethanol; D011493:Protein Kinase C; D010739:Phospholipase D; D013755:Tetradecanoylphorbol Acetate; D001839:Bombesin