title: Differential regulation and relocalization of the platelet P2Y receptors after activation: a way to avoid loss of hemostatic properties?
abstract: In the present study, we investigated the desensitization and trafficking of the P2Y1 and P2Y12 receptors after agonist-induced stimulation of platelets or astrocytoma cells transfected with the P2Y1 or P2Y12 receptors fused to green fluorescent protein. In platelets and in transfected cells, exposure to 10 microM ADP caused desensitization of the P2Y1 receptor-driven calcium signal, whereas the P2Y12 receptor-mediated inhibition of cAMP formation was not affected. Plasma membranes from ADP-stimulated platelets also retained P2Y12 activity. Agonist-induced P2Y1 receptor desensitization was accompanied by its internalization in platelets and transfected cells. In contrast, although a substantial fraction of P2Y12 receptors was rapidly and transiently internalized, most of the P2Y12 receptors remained at the plasma membrane. Activated P2Y1 receptors were internalized through a clathrin-dependent pathway in cells and platelets, whereas the P2Y12 receptors seemed to use a distinct, clathrin-independent pathway. Together, these data indicate that the P2Y1 and P2Y12 receptors are differentially regulated upon activation. The absence of desensitization of the Gi protein-coupled P2Y12 receptor-dependent responses could represent a mechanism to preserve the hemostatic properties of otherwise unresponsive platelets.
authors.affiliation: Laboratoire de Biologie et de Pharmacologie de l'Hémostase et de la Thrombose, INSERM U.311, Etablissement Français du Sang-Alsace, 10 rue Spielmann, BP 36, 67065 Strasbourg Cedex, France.
authors.forename: Anthony
authors.initials: A
authors.lastname: Baurand
authors.forename: Anita
authors.initials: A
authors.lastname: Eckly
authors.forename: Béatrice
authors.initials: B
authors.lastname: Hechler
authors.forename: Gilles
authors.initials: G
authors.lastname: Kauffenstein
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Galzi
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Cazenave
authors.forename: Catherine
authors.initials: C
authors.lastname: Léon
authors.forename: Christian
authors.initials: C
authors.lastname: Gachet
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D001254:Astrocytoma; D001792:Blood Platelets / Q000502:physiology*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000502:physiology; D000242:Cyclic AMP / Q000378:metabolism; D006487:Hemostasis / Q000502:physiology*; D006801:Humans; D008565:Membrane Proteins / Q000097:blood* / Q000737:chemistry / Q000502:physiology; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D018048:Receptors, Purinergic P2 / Q000097:blood* / Q000737:chemistry / Q000502:physiology; D058472:Receptors, Purinergic P2Y1; D058925:Receptors, Purinergic P2Y12; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection
chemical_list: D008565:Membrane Proteins; C546382:P2RY1 protein, human; C548576:P2RY12 protein, human; D010446:Peptide Fragments; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; D058925:Receptors, Purinergic P2Y12; D011993:Recombinant Fusion Proteins; D000244:Adenosine Diphosphate; D000242:Cyclic AMP