Costimulation of the Gi-coupled ADP receptor and the Gq-coupled TXA2 receptor is required for ERK2 activation in collagen-induced platelet aggregation.
The stimulation of platelets by low doses of collagen induces extracellular signal-regulated kinase 2 (ERK2) activation. In this report, we demonstrate that collagen-induced ERK2 activation depends on thromboxane A(2) (TXA(2)) formation and ADP release. The collagen-induced ERK2 activation was inhibited by indomethacin (88%) and by AR-C69931MX (70%), a specific antagonist of P2Y12, a Gi-coupled ADP receptor. AR-C69931MX (10 microM) inhibition was overcome by epinephrine (1 microM), an agonist of the Gi-coupled alpha(2A)-adrenergic receptor, suggesting that the Gi-coupled receptor was necessary for ERK2 activation by collagen. By contrast, MRS 2179 (10 microM), a specific antagonist of P2Y1, a Gq-coupled ADP receptor, did not affect collagen-induced ERK2 activation. Little or no ERK2 activation was observed with ADP alone (10 microM). By contrast, U46619 (10 microM), a stable analog of TXA(2), induced ERK2 activation in an ADP-dependent manner, via the P2Y12 receptor. These results suggest that the Gi-dependent signaling pathway, stimulated by ADP or epinephrine, was not the only pathway required for ERK2 activation by collagen. Costimulation of the specific G(12/13)-coupled TXA(2) receptor with a low dose of U46619 (10 nM) and of Gi- and Gq-coupled ADP receptor (10 microM) induced very low levels of ERK2 activation, similar to those observed with ADP alone, suggesting that G(12/13) is not involved or not sufficient to induce the additional pathway necessary for ERK2 activation. The Gq-coupled TXA(2) receptor was required for ERK2 activation by U46619 (10 microM) and low doses of collagen, clearly showing that a coordinated pathway through both Gq from TXA(2) and Gi from ADP was necessary for ERK2 activation. Finally, we demonstrate that ERK2 activation is involved in collagen-induced aggregation and secretion.
Roger
Séverine
S
U348 INSERM, IFR 6 Circulation Lariboisière, Hôpital Lariboisière, 41 Bd de la Chapelle, 75475 Cedex 10, Paris, France.
Pawlowski
Marc
M
Habib
Aïda
A
Jandrot-Perrus
Martine
M
Rosa
Jean Philippe
JP
Bryckaert
Marijke
M
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000378:metabolism / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000249:Adenosine Monophosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D003094:Collagen / Q000378:metabolism / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D004837:Epinephrine / Q000494:pharmacology; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D006801:Humans; D038982:Integrin alpha2beta1 / Q000378:metabolism; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D010766:Phosphorylation; D010974:Platelet Aggregation / Q000187:drug effects*; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058925:Receptors, Purinergic P2Y12; D044244:Receptors, Thromboxane A2, Prostaglandin H2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D013928:Thromboxane A2 / Q000378:metabolism* / Q000494:pharmacology
D038982:Integrin alpha2beta1; D008565:Membrane Proteins; C548576:P2RY12 protein, human; D010980:Platelet Membrane Glycoproteins; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058925:Receptors, Purinergic P2Y12; D044244:Receptors, Thromboxane A2, Prostaglandin H2; C098341:platelet membrane glycoprotein VI; D000249:Adenosine Monophosphate; D013928:Thromboxane A2; D000244:Adenosine Diphosphate; C117446:cangrelor; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D003094:Collagen; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D004837:Epinephrine