Phosphatidic acid potentiates G(alpha)q stimulation of phospholipase C-beta1 signaling.
Phosphatidic acid (PA) is interactive with G(alpha)q-linked agonists to stimulate GPCR signaling via phospholipase C-beta(1) (PLC-beta(1)). Phorbol 12-myristate 13-acetate (PMA) increases cellular levels of PA and phospholipase D activity (PLD). This study evaluated whether PMA can stimulate PLC-beta(1) activity via PA, independent of GPCR input in transfected COS 7 cells. PMA alone had little effect on PLC activity in cells co-transfected with PLC-beta(1) and G(alpha)q. Activated G(alpha)q, induced by co-transfecting muscarinic cholinergic receptor (m1R), was necessary for stimulation of PLC-beta(1) activity by PMA. Stimulation by PMA was dependent on the PA-regulatory motif of PLC-beta(1) implicating PA in this mechanism. PLD1 knockdown by antisense decreased responsiveness of PLC-beta(1) to both PMA and carbachol. PA alone thus has little effect on PLC-beta(1) activity, but PA and PLD1 synergize with activated G(alpha)q to stimulate PLC-beta(1) signaling. Coordinate interaction with activated G(alpha)q may serve as an important mechanism to fine tune response to ligands while preventing spurious initiation of PLC-beta signaling by PA in cells.
Litosch
Irene
I
Department of Molecular and Cellular Pharmacology, University of Miami, Miller School of Medicine, Miami, FL 33101-6189, USA. ilitosch@med.miami.edu
D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D004789:Enzyme Activation; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism*; D010712:Phosphatidic Acids / Q000378:metabolism*; D054799:Phospholipase C beta / Q000096:biosynthesis*; D010739:Phospholipase D / Q000378:metabolism; D043643:Receptor, Muscarinic M1 / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection
D010712:Phosphatidic Acids; D043643:Receptor, Muscarinic M1; D054799:Phospholipase C beta; D010739:Phospholipase D; C106801:phospholipase D1; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D013755:Tetradecanoylphorbol Acetate