title: Distinct signaling pathways mediate cardiomyocyte phospholipase D stimulation by endothelin-1 and thrombin.
abstract: Several G protein-coupled receptors which stimulate phospholipase C (PLC) also activate phospholipase D (PLD) in cardiomyocytes. Here, we characterized PLD activation in neonatal rat cardiomyocytes by the PLC-stimulatory thrombin receptor PAR1, in comparison to the endothelin-1 receptor ET(A)R, which induces PLD stimulation by activation of protein kinase C (PKC) delta and epsilon. Similar to ET(A)R, activation of PAR1 induced PLD stimulation, which, however, was insensitive to PKC inhibition. Furthermore, in contrast to ET(A)R, PLD stimulation by PAR1 was suppressed by overexpression of regulators of G protein signaling specific for G(12)-type G proteins and treatment with brefeldin A, an inhibitor of guanine nucleotide exchange factors for ADP-ribosylation factor (ARF) GTPases. On the other hand, inactivation of Rho GTPases by Clostridium difficile toxin B and treatment with general tyrosine kinase inhibitors suppressed PAR1- and ET(A)R- as well as phorbol ester-induced PLD stimulation and was associated with a fall in the cellular level of phosphatidylinositol 4,5-bisphosphate (PIP(2)). We conclude that, in contrast to ET(A)R-PLD coupling, PAR1-induced cardiomyocyte PLD stimulation is PKC-independent and mediated by G(12)-type G proteins and ARF GTPases, while Rho and tyrosine kinases regulate PLD stimulation by either receptor, apparently by controlling the cellular level of PIP(2), a common regulator of PLD activity.
authors: Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
authors: Mercedeh
authors: M
authors: Fahimi-Vahid
authors: Nils
authors: N
authors: Gosau
authors: Christina
authors: C
authors: Michalek
authors: Li
authors: L
authors: Han
authors: Karl H
authors: KH
authors: Jakobs
authors: Martina
authors: M
authors: Schmidt
authors: Neil
authors: N
authors: Roberts
authors: Metin
authors: M
authors: Avkiran
authors: Thomas
authors: T
authors: Wieland
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D019332:Endothelin-1 / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism; D019833:Genistein / Q000378:metabolism; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D010703:Phorbol Esters / Q000378:metabolism; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D010739:Phospholipase D / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology; D013917:Thrombin / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D019332:Endothelin-1; D010703:Phorbol Esters; D019269:Phosphatidylinositol 4,5-Diphosphate; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D010738:Type C Phospholipases; D010739:Phospholipase D; D013917:Thrombin; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins