Thromb Haemost 1999; 82(04): 1322-1326
DOI: 10.1055/s-0037-1614384
Review Article
Schattauer GmbH

Role of Intracellular Signaling Events in ADP-induced Platelet Aggregation

James L. Daniel
2   Pharmacology, and the Temple University Medical School, Philadelphia, USA
3   Sol Sherry Thrombosis Research Center, Temple University Medical School, Philadelphia, USA
,
Carol Dangelmaier
3   Sol Sherry Thrombosis Research Center, Temple University Medical School, Philadelphia, USA
,
Jianguo Jin
1   From the Departments of Physiology, Temple University Medical School, Philadelphia, USA
,
Young B. Kim
1   From the Departments of Physiology, Temple University Medical School, Philadelphia, USA
,
Satya P. Kunapuli
1   From the Departments of Physiology, Temple University Medical School, Philadelphia, USA
2   Pharmacology, and the Temple University Medical School, Philadelphia, USA
3   Sol Sherry Thrombosis Research Center, Temple University Medical School, Philadelphia, USA
› Institutsangaben
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Publikationsverlauf

Received 13. April 1999

Accepted after revision 04. Juni 1999

Publikationsdatum:
08. Dezember 2017 (online)

Summary

Human platelets express two distinct G protein-coupled ADP receptors, one coupled to phospholipase C through Gq, P2Y1, and the other to inhibition of adenylyl cyclase through Gi, P2TAC. We have recently shown that concomitant intracellular signaling from both the P2TAC and P2Y1 receptors is essential for ADP-induced platelet aggregation. Previous studies have tested whether ADP causes a decrease in the basal cAMP level and this reduction promotes platelet aggregation, but did not study the effect of decreased cAMP levels when the Gq pathway is selectively activated. Since we are now aware that platelet aggregation requires activation of two receptors, we investigated whether the function of P2TAC receptor activation, leading to inhibition of platelet adenylyl cyclase, could be replaced by direct inhibition of adenylyl cyclase, when Gq pathway is also activated, a possibility that has not been addressed to date. In the present study, we supplemented the P2Y1 mediated Gq signaling pathway with inhibition of the platelet adenylyl cyclase by using SQ22536 or dideoxyadenosine, or by selective activation of the α2A adrenoceptors with epinephrine. Although SQ22536, dideoxyadenosine, and epinephrine reduced the cAMP levels, only epinephrine could mimic the P2TAC receptor mediated signaling events, suggesting that reduction in basal cAMP levels does not directly contribute to ADP-induced platelet activation. Adenosine-5’-phosphate-3’-phosphosulfate, a P2Y1 receptor antagonist, completely blocked ADP-induced inositol 1,4,5-trisphosphate and inositol 1,3,4-trisphosphate formation suggesting that P2TAC-mediated activation of Gi (or other G proteins) does not activate phospholipase C. These results suggest that a signaling event downstream from Gi, independent of the inhibition of platelet adenylyl cyclase, contributes to αIIbβ3 activation.

 
  • References

  • 1 Holmsen H, Weiss HJ. Secretable storage pools in platelets. Annu Rev Med 1979; 30: 119-34.
  • 2 Gachet C, Hechler B, Leon C, Vial C, Leray C, Ohlmann P, Cazenave JP. Activation of ADP receptors and platelet function. Thromb Haemost 1997; 78: 271-5.
  • 3 Mills DC. ADP receptors on platelets. Thromb Haemost 1996; 76: 835-56.
  • 4 Kunapuli SP. Multiple P2 receptor subtypes on platelets: A new interpretation of their function. Trends in Pharmacological Sci 1998; 19: 391-4.
  • 5 Bennett JS, Chan C, Vilaire G, Mousa SA, DeGrado WF. Agonist-activated alphavbeta3 on platelets and lymphocytes binds to the matrix protein osteopontin. J Biol Chem 1997; 272: 8137-40.
  • 6 Gordon J. Extracellular ATP: effects, sources and fates. Biochem J 1986; 233: 309-19.
  • 7 MacKenzie AB, Mahaut-Smith MP, Sage SO, Nakamura F, Amieva MR, Furthmayr H. Activation of receptor-operated cation channels via P2X1 not P2T purinoceptors in human platelets Phosphorylation of threonine 558 in the carboxyl-terminal actin-binding domain of moesin by thrombin activation of human platelets. Journal of Biological Chemistry 1996; 270: 31377-85.
  • 8 Daniel JL, Dangelmaier C, Jin J, Ashby B, Smith JB, Kunapuli SP. Molecular basis for ADP-induced platelet activation. I. Evidence for three distinct ADP receptors on human platelets. J Biol Chem 1998; 273: 2024-9.
  • 9 Jin J, Daniel JL, Kunapuli SP. Molecular basis for ADP-induced platelet activation. II. The P2Y1 receptor mediates ADP-induced intracellular calcium mobilization and shape change in platelets. J Biol Chem 1998; 273: 2030-4.
  • 10 Fagura MS, Dainty IA, McKay GD, Kirk IP, Humphries RG, Robertson MJ, Dougall IG, Leff P. P2y(1)-receptors in human platelets which are pharmacologically distinct from P2y(ADP)-receptors. British Journal of Pharmacology 1998; 124: 157-64.
  • 11 Geiger J, Honigliedl P, Schanzenbacher P, Walter U. Ligand specificity and ticlopidine effects distinguish three human platelet ADP receptors. European Journal of Pharmacology 1998; 351: 235-46.
  • 12 Hechler B, Leon C, Vial C, Vigne P, Frelin C, Cazenave JP, Gachet C. The P2y(1) receptor is necessary for adenosine 5’-diphosphate-induced platelet aggregation. Blood 1998; 92: 152-9.
  • 13 Jantzen H-M, Gousset L, Bhaskar V, Vincent D, Tai A, Reynolds E, Conley PD. Evidence for two distinct G protein-coupled ADP receptors mediating platelet activation. Thromb Haemost 1998; 81: 111-7.
  • 14 Boyer JL, Romeroavila T, Schachter JB, Harden TK. Identification of competitive antagonists of the P2y(1) receptor. Mol Pharmacol 1996; 50: 1323-9.
  • 15 Jin J, Kunapuli SP. Coactivation of two different G protein-coupled receptors is essential for ADP-induced platelet aggregation. Proc Natl Acad Sci USA 1998; 95: 8070-4.
  • 16 Savi P, Beauverger P, Labouret C, Delfaud M, Salel V, Kaghad M, Herbert JM. Role of P2Y1 purinoceptor in ADP-induced platelet activation. FEBS Lett 1998; 422: 291-5.
  • 17 Savi P, Bornia J, Salel V, Delfaud M, Herbert JM. Characterization of P2x1 purinoreceptors on rat platelets – Effect of clopidogrel. British Journal of Haematology 1997; 98: 880-6.
  • 18 Salzman EW. Cyclic AMP in platelet function. New Engl J Med 1972; 286: 358-63.
  • 19 Haslam RJ, Davidson MM, Desjardins JV. Inhibition of adenylate cyclase by adenosine analogues in preparations of broken and intact human platelets. Evidence for the unidirectional control of platelet function by cyclic. AMP Biochem J 1978; 176: 83-95.
  • 20 Gabbeta J, Yang X, Sun L, McLane MA, Niewiarowski S, Rao AK. Abnormal inside-out signal transduction-dependent activation of glycoprotein IIb-IIIa in a patient with impaired pleckstrin phosphorylation. Blood 1996; 87: 1368-76.
  • 21 Daniel JL, Dangelmaier CA, Smith JB. Formation and metabolism of inositol 1,4,5-trisphosphate in human platelets. Biochem J 1987; 246: 109-14.
  • 22 Locati M, Murphy PM. Chemokines and chemokine receptors: biology and clinical relevance in inflammation and AIDS [In Process Citation]. Annu Rev Med 1999; 50: 425-40.
  • 23 van Willigen G, Donath J, Lapetina EG, Akkerman JW. Identification of alpha-subunits of trimeric GTP-binding proteins in human platelets by RT-PCR. Biochem Biophys Res Commun 1995; 214: 254-62.
  • 24 Offermanns S, Hu YH, Simon MI. Galpha12 and galpha13 are phosphorylated during platelet activation. Journal of Biological Chemistry 1996; 271: 26044-8.
  • 25 Klages B, Brandt U, Simon MI, Schultz G, Offermanns S. Activation of G12/G13 results in shape change and Rho/Rho-Kinase-mediated myosin light chain phosphorylation in mouse platelets. J Cell Biol 1999; 144: 745-54.