title: The P2X(7) receptor-mediated phospholipase D activation is regulated by both PKC-dependent and PKC-independent pathways in a rat brain-derived Type-2 astrocyte cell line, RBA-2.
abstract: The aim of this study was to characterize the regulatory mechanisms of the P2X(7) receptor (P2X(7)R)-mediated phospholipase D (PLD) activation in a rat brain-derived Type-2 astrocyte cell line, RBA-2. A time course study revealed that activation of P2X(7)R resulted in a choline and not phosphorylcholine formation, suggesting that activation of P2X(7)R is associated with the phosphatidylcholine-PLD (PC-PLD) in these cells. GF 109203X, a selective protein kinase C (PKC) inhibitor, partially inhibited the P2X(7)R-mediated PLD activation, while blocking the phorbol 12-myristate 13-acetate (PMA)-stimulated PLD activity. In addition, PMA synergistically activated the P2X(7)R-mediated PLD activity. Furthermore, genistein, a tyrosine kinase inhibitor, blocked the P2X(7)R-activated PLD, while KN62, a Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) inhibitor, was less effective, whereas the mitogen-activated protein kinase (MAPK) inhibitor PD98059 was ineffective. No additive inhibitory effects were found by simultaneous treatment of GF 109203X and KN62 on P2X(7)R-activated PLD. Taken together, these results demonstrate that both PKC-dependent and PKC-independent signaling pathways are involved in the regulation of P2X(7)R-mediated PLD activation. Additionally, CaMKII may participate in the PKC-dependent pathway, and tyrosine kinase may play a pivotal role on both PKC-dependent and PKC-independent pathways in the P2X(7)R-mediated PLD activation in RBA-2 cells.
authors.affiliation: Institute of Neuroscience, College of Life Science, National Yang Ming University, No. 155, Section 2, Li-Non Street, Shi-Pai, Taipei 112, Taiwan, ROC.
authors.forename: Amos C
authors.initials: AC
authors.lastname: Hung
authors.forename: Synthia H
authors.initials: SH
authors.lastname: Sun
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D001921:Brain / Q000166:cytology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000502:physiology; D002460:Cell Line; D004357:Drug Synergism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007700:Kinetics; D008301:Maleimides / Q000494:pharmacology; D010739:Phospholipase D / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D058910:Purinergic P2 Receptor Agonists; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000502:physiology*; D058486:Receptors, Purinergic P2X7; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; C546470:P2rx7 protein, rat; D058910:Purinergic P2 Receptor Agonists; D012333:RNA, Messenger; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010738:Type C Phospholipases; C105598:phosphatidylcholine-specific phospholipase C; D010739:Phospholipase D; C070515:bisindolylmaleimide I; D013755:Tetradecanoylphorbol Acetate