Phospholipase D hydrolysis of plasmalogen and diacyl ethanolamine phosphoglycerides by protein kinase C dependent and independent mechanisms

Ethanolamine phosphoglycerides (EPG) are potential sources of lipid second messengers in signal transduction pathways. We investigated EPG turnover, including both 1-alkenyl-2acyl- (plasmalogen) and diacyl-classes, in response to stimulation of protein kinase C (PKC) by phorbol ester (4β-12-O-tetradecanoylphorbol-l3-acetate (TPA)) in cultured C6 rat glioma cells. Release of ethanolamine to the medium from EPG prelabeled with [14C]ethanolamine indicated that initial ( < 60 min) TPA-stimulated hydrolysis of EPG was predominantly by phospholipase D (PLD). Effects of TPA on PLD activity specifically with EPG was confirmed using trans-phosphatidylation by incubating cells prelabeled with [14C]eicosapentaenoic acid (20:5n-3) with 100 nM TPA and 1% butanol. Analysis of