Role of Phospholipase D-Derived Phosphatidic Acid as a Substrate for Phospholipase A₂ in RBL-2H3 Cells

Abstract

The implications of phospholipase D (PLD) in cytosolic phospholipase A₂ (cPLA₂) activation were studied in a mast cell line, RBL-2H3, upon stimulation with antigen. Antigen-stimulated prostaglandin D₂ generation was apparently suppressed by ethanol with a concomitant decrease in phosphatidic acid (PA) formation. The prostaglandin D₂ generation was also inhibited almost completely by methyl arachidonyl fluorophosphate (MAFP), an inhibitor of cPLA₂, but not by diacylglycerol lipase inhibitor. Furthermore, stimulation with antigen resulted in an increase in lysophosphatidic acid formation, which was suppressed by MAFP in parallel with an increase in PA formation. These results suggest that PA formed by the catalytic action of PLD is used as a substrate for cPLA₂. thus PLD regulates cPLA₂ activation in antigen-stimulated RBL-2H3 cells.