Platelets: Physiology and Biochemistry

ABSTRACT

Platelets are specialized blood cells that play central roles in physiologic and pathologic processes of hemostasis, inflammation, tumor metastasis, wound healing, and host defense. Activation of platelets is crucial for platelet function that includes a complex interplay of adhesion and signaling molecules. This article gives an overview of the activation processes involved in primary and secondary hemostasis, for example, platelet adhesion, platelet secretion, platelet aggregation, microvesicle formation, and clot retraction/stabilization. In addition, activated platelets are predominantly involved in cross talk to other blood and vascular cells. Stimulated “sticky” platelets enable recruitment of leukocytes at sites of vascular injury under high shear conditions. Platelet-derived microparticles as well as soluble adhesion molecules, sP-selectin and sCD40L, shed from the surface of activated platelets, are capable of activating, in turn, leukocytes and endothelial cells. This article focuses further on the new view of receptor-mediated thrombin generation of human platelets, necessary for the formation of a stable platelet-fibrin clot during secondary hemostasis. Finally, special emphasis is placed on important stimulatory and inhibitory signaling pathways that modulate platelet function.

KEYWORDS

Platelet activation - platelet adhesion - platelet aggregation - procoagulant activity - thrombin generation

REFERENCES

• 1 Bhatt D L, Topol E J. Scientific and therapeutic advances in antiplatelet therapy.  Nat Rev Drug Discov. 2003;  2 15-28
• 2 Shattil S J, Ginsberg M H, Brugge J S. Adhesive signaling in platelets.  Curr Opin Cell Biol. 1994;  6 695-704
• 3 Fox J E. The platelet cytoskeleton.  Thromb Haemost. 1993;  70 884-893
• 4 Clemetson K J, Clemetson J M. Platelet GPIb-V-IX complex. Structure, function, physiology, and pathology.  Semin Thromb Hemost. 1995;  21 130-136
• 5 Jurk K, Clemetson K J, de Groot P G et al.. Thrombospondin-1 mediates platelet adhesion at high shear via glycoprotein Ib (GPIb): an alternative/backup mechanism to von Willebrand factor.  FASEB J. 2003;  17 1490-1492
• 6 Frenette P S, Denis C V, Weiss L et al.. P-Selectin glycoprotein ligand 1 (PSGL-1) is expressed on platelets and can mediate platelet-endothelial interactions in vivo.  J Exp Med. 2000;  191 1413-1422
• 7 Romo G M, Dong J F, Schade A J et al.. The glycoprotein Ib-IX-V complex is a platelet counterreceptor for P-selectin.  J Exp Med. 1999;  190 803-814
• 8 Kehrel B. Platelet-collagen interactions.  Semin Thromb Hemost. 1995;  21 123-129
• 9 Kehrel B, Balleisen L, Kokott R et al.. Deficiency of intact thrombospondin and membrane glycoprotein Ia in platelets with defective collagen-induced aggregation and spontaneous loss of disorder.  Blood. 1988;  71 1074-1078
• 10 Polgar J, Clemetson J M, Kehrel B E et al.. Platelet activation and signal transduction by convulxin, a C-type lectin from Crotalus durissus terrificus (tropical rattlesnake) venom via the p62/GPVI collagen receptor.  J Biol Chem. 1997;  272 13576-13583
• 11 Kehrel B E, Wierwille S, Clemetson K J et al.. Glycoprotein VI is a major collagen receptor for platelet activation: it recognizes the platelet-activating quaternary structure of collagen, whereas CD36, glycoprotein IIb/IIIa, and von Willebrand factor do not.  Blood. 1998;  91 491-499
• 12 Clemetson J M, Polgar J, Magnenat E, Wells T N, Clemetson K J. The platelet collagen receptor glycoprotein VI is a member of the immunoglobulin superfamily closely related to FcalphaR and the natural killer receptors.  J Biol Chem. 1999;  274 29019-29024
• 13 Rendu F, Brohard-Bohn B. The platelet release reaction: granules’ constituents, secretion and functions.  Platelets. 2001;  12 261-273
• 14 Gachet C. ADP receptors of platelets and their inhibition.  Thromb Haemost. 2001;  86 222-232
• 15 Fabre J E, Nguyen M, Latour A et al.. Decreased platelet aggregation, increased bleeding time and resistance to thromboembolism in P2Y1-deficient mice.  Nat Med. 1999;  5 1199-1202
• 16 Dorsam R T, Kunapuli S P. Central role of the P2Y(12) receptor in platelet activation.  J Clin Invest. 2004;  113 340-345
• 17 Marcus A J, Broekman M J, Drosopoulos J H et al.. The endothelial cell ecto-ADPase responsible for inhibition of platelet function is CD39.  J Clin Invest. 1997;  99 1351-1360
• 18 Dale G L, Friese P, Batar P et al.. Stimulated platelets use serotonin to enhance their retention of procoagulant proteins on the cell surface.  Nature. 2002;  415 175-179
• 19 Nesbitt W S, Giuliano S, Kulkarni S, Dopheide S M, Harper I S, Jackson S P. Intercellular calcium communication regulates platelet aggregation and thrombus growth.  J Cell Biol. 2003;  160 1151-1161
• 20 Kehrel B, Flicker E, Wigbels B, Osterfeld M, van de Loo J, Luscher E F. Thrombospondin measured in whole blood-an indicator of platelet activation.  Blood Coagul Fibrinolysis. 1996;  7 202-205
• 21 Singbartl K, Forlow S B, Ley K. Platelet, but not endothelial, P-selectin is critical for neutrophil-mediated acute postischemic renal failure.  FASEB J. 2001;  15 2337-2344
• 22 Furie B, Furie B C, Flaumenhaft R. A journey with platelet P-selectin: the molecular basis of granule secretion, signalling and cell adhesion.  Thromb Haemost. 2001;  86 214-221
• 23 Lüscher E F, Weber A. The formation of the haemostatic plug-a special case of platelet aggregation. An experiment and a survey of the literature.  Thromb Haemost. 1993;  70 234-237
• 24 Phillips D R, Law D, Scarborough R M. Glycoprotein IIb-IIIa in platelet aggregation: an emerging target for the prevention of acute coronary thrombotic occlusions.  Arch Pathol Lab Med. 1998;  122 811-812
• 25 Payrastre B, Missy K, Trumel C, Bodin S, Plantavid M, Chap H. The integrin alpha IIb/beta 3 in human platelet signal transduction.  Biochem Pharmacol. 2000;  60 1069-1074
• 26 Lahav J, Jurk K, Hess O et al.. Sustained integrin ligation involves extracellular free sulfhydryls and enzymatically catalyzed disulfide exchange.  Blood. 2002;  100 2472-2478
• 27 Morgenstern E, Kehrel B E, Matzdorff A et al.. How do platelets aggregate?.  , [abstract] Ann Hematol. 2001;  80 48
• 28 Ruggeri Z M. Mechanisms of shear-induced platelet adhesion and aggregation.  Thromb Haemost. 1993;  70 119-123
• 29 Puccetti L, Pasqui A L, Pastorelli M et al.. Platelet hyperactivity after statin treatment discontinuation.  Thromb Haemost. 2003;  90 476-482
• 30 Falati S, Liu Q, Gross P et al.. Accumulation of tissue factor into developing thrombi in vivo is dependent upon microparticle P-selectin glycoprotein ligand 1 and platelet P-selectin.  J Exp Med. 2003;  197 1585-1598
• 31 Huo Y, Schober A, Forlow S B et al.. Circulating activated platelets exacerbate atherosclerosis in mice deficient in apolipoprotein E.  Nat Med. 2003;  9 61-67
• 32 Esposito C J, Popescu W M, Rinder H M et al.. Increased leukocyte-platelet adhesion in patients with graft occlusion after peripheral vascular surgery.  Thromb Haemost. 2003;  90 1128-1134
• 33 Hoffmeister K M, Josefsson E C, Isaac N A, Clausen H, Hartwig J H, Stossel T P. Glycosylation restores survival of chilled blood platelets.  Science. 2003;  301 1531-1534
• 34 Bouchard B A, Catcher C S, Thrash B R, Adida C, Tracy P B. Effector cell protease receptor-1, a platelet activation-dependent membrane protein, regulates prothrombinase-catalyzed thrombin generation.  J Biol Chem. 1997;  272 9244-9251
• 35 Monroe D M, Hoffman M, Roberts H R. Platelets and thrombin generation.  Arterioscler Thromb Vasc Biol. 2002;  22 1381-1389
• 36 Zwaal R F, Schroit A J. Pathophysiologic implications of membrane phospholipid asymmetry in blood cells.  Blood. 1997;  89 1121-1132
• 37 Dörmann D, Kardoeus J, Zimmermann R E et al.. Flowcytometric analysis of agonist-induced annexin V, factor Va and factor Xa binding to human platelets.  Platelets. 1998;  7 171-177
• 38 Sims P J, Wiedmer T, Esmon C T, Weiss H J, Shattil S J. Assembly of the platelet prothrombinase complex is linked to vesiculation of the platelet plasma membrane. Studies in Scott syndrome: an isolated defect in platelet procoagulant activity.  J Biol Chem. 1989;  264 17049-17057
• 39 Bogdanov V Y, Balasubramanian V, Hathcock J, Vele O, Lieb M, Nemerson Y. Alternatively spliced human tissue factor: a circulating, soluble, thrombogenic protein.  Nat Med. 2003;  9 458-462
• 40 Nesheim M E, Furmaniak-Kazmierczak E, Henin C, Cote G. On the existence of platelet receptors for factor V(a) and factor VIII(a).  Thromb Haemost. 1993;  70 80-86
• 41 Bouchard B A, Tracy P B. Platelets, leukocytes, and coagulation.  Curr Opin Hematol. 2001;  8 263-269
• 42 Oliver J A, Monroe D M, Roberts H R, Hoffman M . Thrombin activates factor XI on activated platelets in the absence of factor XII.  Arterioscler Thromb Vasc Biol. 1999;  19 170-177
• 43 Monroe D M, Hoffman M, Oliver J A, Roberts H R. Platelet activity of high-dose factor VIIa is independent of tissue factor.  Br J Haematol. 1997;  99 542-547
• 44 Scandura J M, Walsh P N. Factor X bound to the surface of activated human platelets is preferentially activated by platelet-bound factor IXa.  Biochemistry. 1996;  35 8903-8913
• 45 Dormann D, Clemetson K J, Kehrel B E. The GPIb thrombin-binding site is essential for thrombin-induced platelet procoagulant activity.  Blood. 2000;  96 2469-2478
• 46 Brass L F. More pieces of the platelet activation puzzle slide into place.  J Clin Invest. 1999;  104 1663-1665
• 47 Holme P A, Orvim U, Hamers M J et al.. Shear-induced platelet activation and platelet microparticle formation at blood flow conditions as in arteries with a severe stenosis.  Arterioscler Thromb Vasc Biol. 1997;  17 646-653
• 48 Wiedmer T, Shattil S J, Cunningham M, Sims P J. Role of calcium and calpain in complement-induced vesiculation of the platelet plasma membrane and in the exposure of the platelet factor Va receptor.  Biochemistry. 1990;  29 623-632
• 49 Nieuwland R, Berckmans R J, Rotteveel-Eijkman R C et al.. Cell-derived microparticles generated in patients during cardiopulmonary bypass are highly procoagulant.  Circulation. 1997;  96 3534-3541
• 50 Henn V, Slupsky J R, Grafe M et al.. CD40 ligand on activated platelets triggers an inflammatory reaction of endothelial cells.  Nature. 1998;  391 591-594
• 51 Hartwell D W, Mayadas T N, Berger G et al.. Role of P-selectin cytoplasmic domain in granular targeting in vivo and in early inflammatory responses.  J Cell Biol. 1998;  143 1129-1141
• 52 Henn V, Steinbach S, Buchner K, Presek P, Kroczek R A. The inflammatory action of CD40 ligand (CD154) expressed on activated human platelets is temporally limited by coexpressed CD40.  Blood. 2001;  98 1047-1054
• 53 Aukrust P, Muller F, Ueland T et al.. Enhanced levels of soluble and membrane-bound CD40 ligand in patients with unstable angina. Possible reflection of T lymphocyte and platelet involvement in the pathogenesis of acute coronary syndromes.  Circulation. 1999;  100 614-620
• 54 Hollenbaugh D, Mischel-Petty N, Edwards C P et al.. Expression of functional CD40 by vascular endothelial cells.  J Exp Med. 1995;  182 33-40
• 55 Andre P, Prasad K S, Denis C V et al.. CD40L stabilizes arterial thrombi by a beta3 integrin-dependent mechanism.  Nat Med. 2002;  8 247-252
• 56 Brass L F. Thrombin and platelet activation.  Chest. 2003;  124 18S-25S
• 57 Hollopeter G, Jantzen H M, Vincent D et al.. Identification of the platelet ADP receptor targeted by antithrombotic drugs.  Nature. 2001;  409 202-207
• 58 Rao A K. Congenital disorders of platelet function: disorders of signal transduction and secretion.  Am J Med Sci. 1998;  316 69-76
• 59 Rinder C S, Student L A, Bonan J L, Rinder H M, Smith B R. Aspirin does not inhibit adenosine diphosphate-induced platelet alpha-granule release.  Blood. 1993;  82 505-512
• 60 Covic L, Misra M, Badar J, Singh C, Kuliopulos A. Pepducin-based intervention of thrombin-receptor signaling and systemic platelet activation.  Nat Med. 2002;  8 1161-1165
• 61 Yang J, Wu J, Kowalska M A et al.. Loss of signaling through the G protein, Gz, results in abnormal platelet activation and altered responses to psychoactive drugs.  Proc Natl Acad Sci USA. 2000;  97 9984-9989
• 62 Clemetson K J. Platelet activation: signal transduction via membrane receptors.  Thromb Haemost. 1995;  74 111-116
• 63 Clemetson K J, Clemetson J M. Platelet collagen receptors.  Thromb Haemost. 2001;  86 189-197
• 64 Bodin S, Viala C, Ragab A, Payrastre B. A critical role of lipid rafts in the organization of a key FcgammaRIIa-mediated signaling pathway in human platelets.  Thromb Haemost. 2003;  89 318-330
• 65 Gao J, Zoller K E, Ginsberg M H, Brugge J S, Shattil S J. Regulation of the pp72syk protein tyrosine kinase by platelet integrin alpha IIb beta 3.  EMBO J. 1997;  16 6414-6425
• 66 Inoue O, Suzuki-Inoue K, Dean W L, Frampton J, Watson S P. Integrin alpha2beta1 mediates outside-in regulation of platelet spreading on collagen through activation of Src kinases and PLCgamma2.  J Cell Biol. 2003;  160 769-780
• 67 Woodside D G, Obergfell A, Leng L et al.. Activation of Syk protein tyrosine kinase through interaction with integrin beta cytoplasmic domains.  Curr Biol. 2001;  11 1799-1804
• 68 Newman P J. Switched at birth: a new family for PECAM-1.  J Clin Invest. 1999;  103 5-9
• 69 Newton-Nash D K, Newman P J. A new role for platelet-endothelial cell adhesion molecule-1 (CD31): inhibition of TCR-mediated signal transduction.  J Immunol. 1999;  163 682-688
• 70 Geiger J. Inhibitors of platelet signal transduction as anti-aggregatory drugs.  Expert Opin Investig Drugs. 2001;  10 865-890
• 71 Aszodi A, Pfeifer A, Ahmad M et al.. The vasodilator-stimulated phosphoprotein (VASP) is involved in cGMP- and cAMP-mediated inhibition of agonist-induced platelet aggregation, but is dispensable for smooth muscle function.  EMBO J. 1999;  18 37-48
• 72 Schwarz U R, Walter U, Eigenthaler M. Taming platelets with cyclic nucleotides.  Biochem Pharmacol. 2001;  62 1153-1161
• 73 Beumer S. IJsseldijk M J. de Groot P G. Sixma J J. Platelet adhesion to fibronectin in flow: dependence on surface concentration and shear rate, role of platelet membrane glycoproteins GP IIb/IIIa and VLA-5, and inhibition by heparin.  Blood. 1994;  84 3724-3733
• 74 Timpl R, Brown J C. The laminins.  Matrix Biol. 1994;  14 275-281
• 75 Fernandez-Patron C, Martinez-Cuesta M A, Salas E et al.. Differential regulation of platelet aggregation by matrix metalloproteinases-9 and -2.  Thromb Haemost. 1999;  82 1730-1735
• 76 Galt S W, Lindemann S, Allen L et al.. Outside-in signals delivered by matrix metalloproteinase-1 regulate platelet function.  Circ Res. 2002;  90 1093-1099
• 77 Bornstein P. Cell-matrix interactions: the view from the outside.  Methods Cell Biol. 2002;  69 7-11
• 78 Angelillo-Scherrer A, de Frutos P, Aparicio C et al.. Deficiency or inhibition of Gas6 causes platelet dysfunction and protects mice against thrombosis.  Nat Med. 2001;  7 215-221
• 79 Moers A, Nieswandt B, Massberg S et al.. G13 is an essential mediator of platelet activation in hemostasis and thrombosis.  Nat Med. 2003;  9 1418-1422
• 80 Abi-Younes S, Si-Tahar M, Luster A D. The CC chemokines MDC and TARC induce platelet activation via CCR4.  Thromb Res. 2001;  101 279-289
• 81 Clemetson K J, Clemetson J M, Proudfoot A E, Power C A, Baggiolini M, Welb T N. Functional expression of CCR1, CCR3, CCR4, and CXCR4 chemokine receptors on human platelets.  Blood. 2000;  96 4046-4054
• 82 Kowalska M A, Ratajczak M Z, Majka M et al.. Stromal cell-derived factor-1 and macrophage-derived chemokine: 2 chemokines that activate platelets.  Blood. 2000;  96 50-57