title: Potentiation of P2X1 ATP-gated currents by 5-hydroxytryptamine 2A receptors involves diacylglycerol-dependent kinases and intracellular calcium.
abstract: Postsynaptic P2X1 ATP-gated channels are expressed in smooth muscle cells of the vascular and genitourinary systems, where they mediate desensitizing neurogenic contractions. Using the model of the isolated rat tail artery, we show that the vasoactive mediator 5-hydroxytryptamine (5-HT), via the 5-HT2A metabotropic receptor, regulates the desensitization kinetics of P2X1 responses by increasing their rate of recovery. Reconstituting the potentiation of P2X1 ATP-gated currents by 5-HT2A receptors in the Xenopus oocyte expression system, we provide evidence that this modulation depends on the activation of novel protein kinase C isoforms and protein kinase D (also named PKCmu) downstream of phospholipase Cbeta. Other major kinases like Ca2+/calmodulin kinase II, protein kinase A, mitogen-activated protein kinases, and tyrosine kinases were found not to be involved. Moreover, we report that buffering intracellular Ca2+ ions with the chelator 1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) decreases the rate of recovery of P2X1 responses and increases their sensitivity to potentiation by 5-HT2A receptors or by the diacylglycerol analog phorbol ester 12-myristate 13-acetate. We conclude that intracellular Ca2+ and a subset of diacylglycerol-dependent protein kinases regulate the activity of P2X1 receptor channels by modulating their recovery from desensitization.
authors.affiliation: Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada.
authors.forename: Ariel R
authors.initials: AR
authors.lastname: Ase
authors.forename: Ramin
authors.initials: R
authors.lastname: Raouf
authors.forename: Danny
authors.initials: D
authors.lastname: Bélanger
authors.forename: Edith
authors.initials: E
authors.lastname: Hamel
authors.forename: Philippe
authors.initials: P
authors.lastname: Séguéla
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000502:physiology; D004075:Diglycerides / Q000494:pharmacology; D015640:Ion Channel Gating; D011493:Protein Kinase C / Q000502:physiology*; D044402:Receptor, Serotonin, 5-HT2A / Q000502:physiology*; D018048:Receptors, Purinergic P2 / Q000502:physiology*; D058469:Receptors, Purinergic P2X; D012701:Serotonin / Q000494:pharmacology; D015398:Signal Transduction; D019311:Staurosporine / Q000494:pharmacology; D010738:Type C Phospholipases / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects; D014981:Xenopus
chemical_list: D004075:Diglycerides; D044402:Receptor, Serotonin, 5-HT2A; D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; D012701:Serotonin; D000255:Adenosine Triphosphate; C089212:protein kinase D; D011493:Protein Kinase C; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010738:Type C Phospholipases; D019311:Staurosporine; D002118:Calcium