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.
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.
Tolhurst
Gwen
G
Department of Physiology, University of Cambridge, Cambridge, CB2 3EG, United Kingdom.
Vial
Catherine
C
Léon
Catherine
C
Gachet
Christian
C
Evans
Richard J
RJ
Mahaut-Smith
Martyn P
MP
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
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