title: Reciprocal cross-talk between P2Y1 and P2Y12 receptors at the level of calcium signaling in human platelets.
abstract: Adenosine diphosphate (ADP), an important platelet agonist, acts through 2 G-protein-coupled receptors (GPCRs), P2Y(1) and P2Y(12), which signal through Gq and Gi, respectively. There is increasing evidence for cross-talk between signaling pathways downstream of GPCRs and here we demonstrate cross-talk between these 2 ADP receptors in human platelets. We show that P2Y(12) contributes to platelet signaling by potentiating the P2Y(1)-induced calcium response. This potentiation is mediated by 2 mechanisms: inhibition of adenylate cyclase and activation of phosphatidylinositol 3 (PI 3)-kinase. Furthermore, the Src family kinase inhibitor PP1 selectively potentiates the contribution to the calcium response by P2Y(12), although inhibition of adenylate cyclase by P2Y(12) is unaffected. Using PP1 in combination with the inhibitor of PI 3-kinase LY294002, we show that Src negatively regulates the PI 3-kinase-mediated component of the P2Y(12) calcium response. Finally, we were able to show that Src kinase is activated through P2Y(1) but not P2Y(12). Taken together, we present evidence for a complex signaling interplay between P2Y(1) and P2Y(12), where P2Y(12) is able to positively regulate P2Y(1) action and P2Y(1) negatively regulates this action of P2Y(12). It is likely that this interplay between receptors plays an important role in maintaining the delicate balance between platelet activation and inhibition during normal hemostasis.
authors.affiliation: Department of Pharmacology, School of Medical Sciences, University Walk, Bristol, BS8 1TD, United Kingdom.
authors.forename: Adam R
authors.initials: AR
authors.lastname: Hardy
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Jones
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Mundell
authors.forename: Alastair W
authors.initials: AW
authors.lastname: Poole
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000097:blood / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D058919:Purinergic P2 Receptor Antagonists; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D020239:Receptor Cross-Talk; D018048:Receptors, Purinergic P2 / Q000097:blood / Q000378:metabolism*; D058472:Receptors, Purinergic P2Y1; D058925:Receptors, Purinergic P2Y12; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: C108123:4-amino-5-(4-methylphenyl)-7-(tert-butyl)pyrazolo(3,4-d)pyrimidine; D000067956:Adenylyl Cyclase Inhibitors; D008565:Membrane Proteins; C546382:P2RY1 protein, human; C548576:P2RY12 protein, human; D058919:Purinergic P2 Receptor Antagonists; D011720:Pyrazoles; D011743:Pyrimidines; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; D058925:Receptors, Purinergic P2Y12; D000244:Adenosine Diphosphate; D000242:Cyclic AMP; D019869:Phosphatidylinositol 3-Kinases; D019061:src-Family Kinases; D000262:Adenylyl Cyclases; D002118:Calcium