title: Interplay between P2Y(1), P2Y(12), and P2X(1) receptors in the activation of megakaryocyte cation influx currents by ADP: evidence that the primary megakaryocyte represents a fully functional model of platelet P2 receptor signaling.
abstract: The difficulty of conducting electrophysiologic recordings from the platelet has restricted investigations into the role of ion channels in thrombosis and hemostasis. We now demonstrate that the well-established synergy between P2Y(1) and P2Y(12) receptors during adenosine diphosphate (ADP)-dependent activation of the platelet alpha(IIb)beta(3) integrin also exists in murine marrow megakaryocytes, further supporting the progenitor cell as a bona fide model of platelet P2 receptor signaling. In patch clamp recordings, ADP (30 microM) stimulated a transient inward current at -70 mV, which was carried by Na(+) and Ca(2+) and was amplified by phenylarsine oxide, a potentiator of certain transient receptor potential (TRP) ion channels by phosphatidylinositol 4,5-bisphosphate depletion. This initial current decayed to a sustained phase, upon which repetitive transient inward cation currents with pre-dominantly P2X(1)-like kinetics were super-imposed. Abolishing P2X(1)-receptor activity prevented most of the repetitive currents, consistent with their activation by secreted adenosine triphosphate (ATP). Recordings in P2Y(1)-receptor-deficient megakaryocytes demonstrated an essential requirement of this receptor for activation of all ADP-evoked inward currents. However, P2Y(12) receptors, through the activation of PI3-kinase, played a synergistic role in both P2Y(1) and P2X(1)-receptor-dependent currents. Thus, direct stimulation of P2Y(1) and P2Y(12) receptors, together with autocrine P2X(1) activation, is responsible for the activation of nonselective cation currents by the platelet agonist ADP.
authors.affiliation: Department of Physiology, University of Cambridge, Cambridge, CB2 3EG, United Kingdom.
authors.forename: Gwen
authors.initials: G
authors.lastname: Tolhurst
authors.forename: Catherine
authors.initials: C
authors.lastname: Vial
authors.forename: Catherine
authors.initials: C
authors.lastname: Léon
authors.forename: Christian
authors.initials: C
authors.lastname: Gachet
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Evans
authors.forename: Martyn P
authors.initials: MP
authors.lastname: Mahaut-Smith
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000494:pharmacology*; D000818:Animals; D001152:Arsenicals / Q000494:pharmacology; D001792:Blood Platelets / Q000737:chemistry / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D002412:Cations / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004553:Electric Conductivity; D008533:Megakaryocytes / Q000187:drug effects / Q000378:metabolism*; D008565:Membrane Proteins / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D058469:Receptors, Purinergic P2X; D058472:Receptors, Purinergic P2Y1; D058925:Receptors, Purinergic P2Y12; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
chemical_list: D001152:Arsenicals; D002412:Cations; D008565:Membrane Proteins; C546383:P2ry1 protein, mouse; C548577:P2ry12 protein, mouse; D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; D058472:Receptors, Purinergic P2Y1; D058925:Receptors, Purinergic P2Y12; C029341:oxophenylarsine; D000246:Adenosine Diphosphate Ribose; D002118:Calcium