This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Santos, M. T. Articles by Marcus, A. J. Search for Related Content PubMed PubMed Citation Articles by Santos, M. T. Articles by Marcus, A. J. Related Collections Cell signalling/signal transduction Platelets

(Circulation. 2000;102:1924.)
© 2000 American Heart Association, Inc.

Clinical Investigation and Reports

Participation of Tyrosine Phosphorylation in Cytoskeletal Reorganization, _IIbß₃ Integrin Receptor Activation, and Aspirin-Insensitive Mechanisms of Thrombin-Stimulated Human Platelets

M. Teresa Santos, PhD; Antonio Moscardó, MS; Juana Vallés, PhD; Marcial Martínez, PhD; Marta Piñón, MS; Justo Aznar, MD, PhD; M. Johan Broekman, PhD; Aaron J. Marcus, MD

From the Research Center and Department of Clinical Pathology (M.T.S., A.M., J.V., M.M., M.P., J.A.), University Hospital La Fe, Valencia, Spain; Division of Hematology and Medical Oncology (M.J.B., A.J.M.), Department of Medicine, VA New York Harbor Health Care System, New York, NY; and Division of Hematology and Medical Oncology (M.J.B., A.J.M.), Departments of Medicine and Pathology, Weill Medical College of Cornell University, New York, NY.

Correspondence to M. Teresa Santos, PhD, Research Center, University Hospital La Fe, Avda Campanar 21, 46009 Valencia, Spain. E-mail santos_ter{at}gva.es

Background—Fibrinogen binding to the active conformation of the _IIbß₃ integrin receptor (glycoprotein IIb/IIIa) and cytoskeletal reorganization are important events in platelet function. Tyrosine phosphorylation of platelet proteins plays an essential role in platelet signal transduction pathways. We studied the participation of tyrosine kinases on these aspects of platelet reactivity and their importance in cyclooxygenase (COX)-1–independent mechanisms in thrombin-stimulated human platelets.

Methods and Results—Using washed platelets from normal donors and tyrphostin-A47 and aspirin as tyrosine kinase and COX-1 inhibitors, respectively, we found that tyrphostin-A47 downregulated (1) the thrombin-activated conformational change of _IIbß₃, (2) actin polymerization and cytoskeletal reorganization, and (3) the quantity of tyrosine-phospho-rylated proteins associated with the reorganized cytoskeleton. The latter are important components of multimolecular signaling complexes. Concomitantly, platelet aggregation and secretion were significantly reduced. Aspirin did not affect receptor activation or tyrosine phosphorylation but did decrease the initial (30-second) burst of actin polymerization. Importantly, aspirin significantly amplified the inhibitory effect of tyrphostin-A47 on all aspects of platelet reactivity that we evaluated.

Conclusions—Tyrosine protein phosphorylation is a regulatory control system of the inside-out mechanism of _IIbß₃ activation and cytoskeletal assembly in thrombin-stimulated human platelets. Inhibition of these aspects of platelet function with tyrphostin-A47 is amplified when platelets are treated with aspirin. Therefore, tyrosine phosphorylation is a major component of early signaling events and of COX-1–independent mechanisms of thrombin-induced platelet reactivity. The study results may indicate a novel target for therapeutic intervention.

Key Words: platelets • tyrosine kinases • glycoproteins • cytoskeleton • aspirin • thrombin

This article has been cited by other articles:

				W.-Y. Wang, Y.-C. Wu, and C.-C. Wu Prevention of Platelet Glycoprotein IIb/IIIa Activation by 3,4-Methylenedioxy-beta-Nitrostyrene, A Novel Tyrosine Kinase Inhibitor Mol. Pharmacol., October 1, 2006; 70(4): 1380 - 1389. [Abstract] [Full Text] [PDF]

				A. J. Begonja, S. Gambaryan, J. Geiger, B. Aktas, M. Pozgajova, B. Nieswandt, and U. Walter Platelet NAD(P)H-oxidase-generated ROS production regulates {alpha}IIb{beta}3-integrin activation independent of the NO/cGMP pathway Blood, October 15, 2005; 106(8): 2757 - 2760. [Abstract] [Full Text] [PDF]

				J. Valles, M. T. Santos, A. Moscardo, M. A. Dasi, and J. Aznar Role of Erythrocytes in Signal Transduction Mechanisms of Recruiting Platelets: Effects on Platelet Tyrosine Phosphorylation and Cytoskeletal Reorganization. Blood (ASH Annual Meeting Abstracts), November 16, 2004; 104(11): 3887 - 3887. [Abstract]

				M. J. Coffey, G. E. Jarvis, J. M. Gibbins, B. Coles, N. E. Barrett, O. R.E. Wylie, and V. B. O'Donnell Platelet 12-Lipoxygenase Activation via Glycoprotein VI: Involvement of Multiple Signaling Pathways in Agonist Control of H(P)ETE Synthesis Circ. Res., June 25, 2004; 94(12): 1598 - 1605. [Abstract] [Full Text] [PDF]

				A. Tabuchi, A. Yoshioka, T. Higashi, R. Shirakawa, H. Nishioka, T. Kita, and H. Horiuchi Direct Demonstration of Involvement of Protein Kinase C{alpha} in the Ca2+-induced Platelet Aggregation J. Biol. Chem., July 11, 2003; 278(29): 26374 - 26379. [Abstract] [Full Text] [PDF]

				J. Valles, M. T. Santos, J. Aznar, M. Martinez, A. Moscardo, M. Pinon, M. J. Broekman, and A. J. Marcus Platelet-erythrocyte interactions enhance alpha IIbbeta 3 integrin receptor activation and P-selectin expression during platelet recruitment: down-regulation by aspirin ex vivo Blood, May 13, 2002; 99(11): 3978 - 3984. [Abstract] [Full Text] [PDF]

				J. W. Eikelboom, J. Hirsh, J. I. Weitz, M. Johnston, Q. Yi, and S. Yusuf Aspirin-Resistant Thromboxane Biosynthesis and the Risk of Myocardial Infarction, Stroke, or Cardiovascular Death in Patients at High Risk for Cardiovascular Events Circulation, April 9, 2002; 105(14): 1650 - 1655. [Abstract] [Full Text] [PDF]