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Burnstock G. Blood cells: an historical account of the roles of purinergic signalling. Purinergic Signal 2015; 11:411-34. [PMID: 26260710 PMCID: PMC4648797 DOI: 10.1007/s11302-015-9462-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 07/23/2015] [Indexed: 12/17/2022] Open
Abstract
The involvement of purinergic signalling in the physiology of erythrocytes, platelets and leukocytes was recognised early. The release of ATP and the expression of purinoceptors and ectonucleotidases on erythrocytes in health and disease are reviewed. The release of ATP and ADP from platelets and the expression and roles of P1, P2Y(1), P2Y(12) and P2X1 receptors on platelets are described. P2Y(1) and P2X(1) receptors mediate changes in platelet shape, while P2Y(12) receptors mediate platelet aggregation. The changes in the role of purinergic signalling in a variety of disease conditions are considered. The successful use of P2Y(12) receptor antagonists, such as clopidogrel and ticagrelor, for the treatment of thrombosis, myocardial infarction and stroke is discussed.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London, NW3 2PF, UK.
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, Australia.
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Wermelinger LS, Geraldo RB, Frattani FS, Rodrigues CR, Juliano MA, Castro HC, Zingali RB. Integrin inhibitors from snake venom: exploring the relationship between the structure and activity of RGD-peptides. Arch Biochem Biophys 2008; 482:25-32. [PMID: 19101499 DOI: 10.1016/j.abb.2008.11.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2008] [Accepted: 11/24/2008] [Indexed: 10/21/2022]
Abstract
alphaIIbbeta3 is an integrin that is involved in platelet adhesion and aggregation. This receptor may be inhibited by cysteine-rich peptides known as disintegrins. We isolated two disintegrins from Bothrops jararaca venom called jarastatin and jararacin. We evaluated the structural characteristics and the effects on human platelet aggregation of these disintegrins. Inhibitory profiles were compared to six distinct peptides synthesized based on their RGD hairpin loop primary sequences. Both jarastatin and jararacin inhibited ADP and thrombin induction. Conversely, none of the cyclic peptides showed high-quality activity in assays induced by ADP or thrombin. We constructed homology models for all of these molecules, and theoretically evaluated their interaction with the alphaIIbbeta3 crystal structure using a molecular modeling approach. These results support the observations that the cyclic peptides had little effects, and also reinforce the observation that residues outside the disintegrin RGD sequence are required for interactions with receptor.
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Affiliation(s)
- Luciana S Wermelinger
- Instituto de Bioquímica Médica, Programa de Biologia Estrutural, CCS, Universidade Federal Rio de Janeiro, CEP 21941-590, Rio de Janeiro, RJ, Brazil
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MEYER D, BAUMGARTNER HR. ROLE OF VON WILLEBRAND FACTOR IN PLATELET ADHESION TO THE SUBENDOTHELIUM. Br J Haematol 2008. [DOI: 10.1111/j.1365-2141.1983.00001.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Suneetha WJ, Krishnakantha TP. Cardamom extract as inhibitor of human platelet aggregation. Phytother Res 2005; 19:437-40. [PMID: 16106388 DOI: 10.1002/ptr.1681] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The inhibitory activity of cardamom extract was studied on human platelets. Platelet aggregation and lipid peroxidation were evaluated with platelet rich plasma (PRP) and platelet membranes, respectively, obtained from blood of healthy volunteers. Human platelets were subjected to stimulation with a variety of agonists including ADP (2.5 mM), epinephrine (2.5 mM), collagen (10 mM), calcium ionophore A 23187 (6 microM) and ristocetin (1.25 microg/mL). The IC50 were 0.49, 0.21, 0.55 and 0.59 mg with ADP, epinephrine, collagen and calcium ionophore A 23187, respectively, and no inhibition with ristocetin. The inhibitory effect was dose dependent with concentrations varying between 0.14 and 0.70 mg and time dependent at IC50. Lipid peroxidation induced by iron--ascorbic acid system in platelet membranes was analysed with malondialdehyde (MDA) as an index. An increase in concentration of cardamom has decreased the MDA formation significantly. Hence, it may be said that aqueous extract of cardamom may have component(s), which protect platelets from aggregation and lipid peroxidation.
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Affiliation(s)
- W Jessie Suneetha
- Department of Biochemistry and Nutrition, Central Food Technological Research Institute, Mysore 570 020, India
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Yamanaka T, Ohkubo M, Kuroda S, Nakamura H, Takahashi F, Aoki T, Mihara K, Seki J, Kato M. Design, synthesis, and structure–activity relationships of potent GPIIb/IIIa antagonists: discovery of FK419. Bioorg Med Chem 2005; 13:4343-52. [PMID: 15927840 DOI: 10.1016/j.bmc.2005.03.056] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Revised: 03/31/2005] [Accepted: 03/31/2005] [Indexed: 11/30/2022]
Abstract
The discovery of the non-peptide antiplatelet injectable agent FK419 is reported. Based on the beta-turn structure of RGD peptide sequences in the alpha chain of fibrinogen, which binds the glycoprotein IIb/IIIa (GPIIb/IIIa) on the surface of platelets to induce platelet aggregation, the prototype 2 was designed. After further substituent effects were investigated at the alpha-position of the carboxylic acid in 2, we enhanced platelet aggregation inhibition, and discovered the useful feature of reduced prolongation of bleeding time. Finally, the potent platelet aggregation inhibitor FK419 (3) could be discovered. FK419 shows a safe feature of reduced prolongation of bleeding time, as well as potent inhibition of platelet aggregation.
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Affiliation(s)
- Toshio Yamanaka
- Medicinal Chemistry Research Laboratories, Fujisawa Pharmaceutical Co., Ltd, 2-1-6 Kashima, Yodogawa-Ku, Osaka 532-8514, Japan.
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Abstract
The adhesive protein von Willebrand factor (VWF) contributes to platelet function by mediating the initiation and progression of thrombus formation at sites of vascular injury. In recent years there has been considerable progress in explaining the biological properties of VWF, including the structural and functional characteristics of specific domains. The mechanism of interaction between the VWF A1 domain and glycoprotein Ibalpha has been elucidated in detail, bringing us closer to understanding how this adhesive bond can oppose the fluid dynamic effects of rapidly flowing blood contributing to platelet adhesion and activation. Moreover, novel findings have been obtained on the link between regulation of VWF multimer size and microvascular thrombosis. This progress in basic research has provided critical information to define with greater precision the role of VWF in vascular biology and pathology, including its possible involvement in the onset of atherosclerosis and its acute thrombotic complications.
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Affiliation(s)
- Z M Ruggeri
- Roon Research Laboratory for Arteriosclerosis and Thrombosis, Division of Experimental Thrombosis and Hemostasis, Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, USA.
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Ruggeri ZM. Structure of von Willebrand factor and its function in platelet adhesion and thrombus formation. Best Pract Res Clin Haematol 2001; 14:257-79. [PMID: 11686099 DOI: 10.1053/beha.2001.0133] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The adhesive protein von Willebrand factor mediates the initiation and progression of thrombus formation at sites of vascular injury. von Willebrand factor is synthesized in endothelial cells and megakaryocytes as a very large polymer composed of identical subunits. In the plasma, it appears as a series of multimers of regularly decreasing molecular mass, from several thousand to 500 kDa. The size of circulating von Willebrand factor multimers is controlled by proteolytic cleavage carried out by a specific protease. The biological functions of von Willebrand factor are exerted through specific domains that interact with extracellular matrix components and cell membrane receptors to promote the initial tethering and adhesion of platelets to subendothelial surfaces, as well as platelet aggregation. Moreover, von Willebrand factor binds the procoagulant co-enzyme, factor VIII, contributing to its stability and, indirectly, to its function in the generation of fibrin. This chapter presents a review of current knowledge on the structure, biosynthesis and functions of von Willebrand factor.
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Affiliation(s)
- Z M Ruggeri
- Roon Research Center for Arteriosclerosis and Thrombosis, Division of Experimental Hemostasis and Thrombosis, Department of Molecular and Experimental Medicine, Department of Vascular Biology, Scripps Research Institute, La Jolla, California 92037, USA
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Ruggeri ZM. Old concepts and new developments in the study of platelet aggregation. J Clin Invest 2000; 105:699-701. [PMID: 10727435 PMCID: PMC377470 DOI: 10.1172/jci9604] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- Z M Ruggeri
- The Scripps Research Institute, Molecular and Experimental Medicine-175, 10550 N. Torrey Pines Road, La Jolla, California 92037, USA.
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Structural and functional characterization of the mouse von Willebrand factor receptor GPIb-IX with novel monoclonal antibodies. Blood 2000. [DOI: 10.1182/blood.v95.3.886.003k45_886_893] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Five novel monoclonal antibodies (mAbs; p0p 1-5) were used to characterize the structural and functional properties and the in vivo expression of the murine GPIb-IX complex (von Willebrand factor receptor). The molecular weights of the subunits are similar to the human homologs: GPIb (150 kd), GPIbβ (25 kd), and GPIX (25 kd). Activation of platelets with thrombin or PMA predominantly induced shedding of glycocalicin (GC; 130 kd) but only low levels of receptor internalization. The GC concentration in normal mouse plasma was found to be at least 10 times higher than that described for human plasma (approximately 25 μg/mL versus 1-2 μg/mL). Two additional cleavage sites for unidentified platelet-derived proteases were found on GPIb, as demonstrated by the generation of 3 N-terminal fragments during in vitro incubation of washed platelets (GC, 60 kd, 45 kd). Occupancy of GPIb with p0p mAbs or F(ab)2-fragments resulted in aggregate formation in vitro and rapid irreversible thrombocytopenia in vivo, irrespective of the exact binding epitopes of the individual antibodies. GPIb-IX was not detectable immunohistochemically on endothelial cells in the major organs under normal or inflammatory conditions. The authors conclude that the mouse system might become an interesting model for studies on GPIb-IX function and regulation.
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Abstract
This article addresses the flow-dependent differential roles of the platelet receptors, glycoprotein (GP) GPIb and GPIIb-IIIa, in platelet aggregation mediated by ristocetin and soluble von Willebrand factor (vWF), by adenosine diphosphate (ADP) and soluble fibrinogen (Fg), and by thrombin and ADP in absence of exogenous ligands. Platelet-rich plasma or "activated" washed platelets were sheared in a coaxial cylinder at 100 to 1000 sec(-1) or in tubular flow, with surface ligands monitored by flow cytometry, with fluorescently labeled soluble ligands or monoclonal antibodies against specific adhesive domains on receptors or ligands. Aggregation was quantitated by monitoring the change in particle concentration with time by particle counting, and expressed as Capture efficiencies (CE) = Experimental/calculated initial rates of aggregation. The contributions of adhesive domains on putative ligands or receptors mediating aggregation at any given flow condition were evaluated with monoclonal antibodies or peptides known to block these adhesive sites. Surprisingly, ristocetin, which "chemically activates" GPIb/vWF to mediate spontaneous binding of the ligand to its receptor, at low concentrations yielding <2000 platelet-bound vWF monomers, gave efficient aggregation even at 1000 sec(-1) (CE = 0.34 +/- 0.02, n = 11) with only GPIb required. The physiologic activators ADP and thrombin both supported efficient aggregation of washed platelets with no exogenous ligands at 1000 sec(-1) by surface-secreted vWF (CE = 0.08 +/- 0.01, n = 6), in contrast to poorer ADP and soluble Fg-mediated aggregation in the absence of secretion (CE = 0.05). The secreted, platelet-bound, vWF-mediated aggregation completely depends on GPIIb-IIIa but partially and increasingly requires GPIb with increasing shear. Molecular models for these interactions are presented in terms of "rolling" and "firm" capture. Flow conditions will be critically important in designing and selecting anti-thrombotic drugs directed against the appropriate adhesive domains on receptors and ligands, which likely include other members such as thrombospondin and P-selectin.
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Affiliation(s)
- M M Frojmovic
- Department of Physiology, McGill University, Montreal, Quebec, Canada.
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Minami N, Suzuki Y, Yamamoto M, Kihira H, Imai E, Wada H, Kimura Y, Ikeda Y, Shiku H, Nishikawa M. Inhibition of shear stress-induced platelet aggregation by cilostazol, a specific inhibitor of cGMP-inhibited phosphodiesterase, in vitro and ex vivo. Life Sci 1998; 61:PL 383-9. [PMID: 9416770 DOI: 10.1016/s0024-3205(97)00986-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cilostazol(6-[4-(1-cyclohexyl-1H-tetrazol-5-yl)-butoxy]-3,4- dihydro-2(1H)-quinolinone) selectively inhibits cGMP-inhibited phosphodiesterase (PDE3) and is a potent inhibitor of platelet aggregation induced by various agonists. Effect of cilostazol on shear stress-induced human platelet aggregation (SIPA) was examined in vitro and ex vivo. Cilostazol inhibited SIPA dose-dependently in vitro. The IC50 value of cilostazol for inhibition of SIPA was 15 +/- 2.6 microM (m +/- SE, n=5), which was very similar to that (12.5 +/- 2.1 microM) for inhibition of ADP-induced platelet aggregation. Cilostazol potentiates the inhibition of SIPA by PGE1 and enhances its ability to increase cAMP concentrations. A single oral adminstration of 100 mg cilostazol to healthy volunteers produced a significant inhibition of SIPA. This study demonstrates that cilostazol is an effective inhibitor of SIPA, which may be important for the prevention and the treatment of arterial occlusive diseases.
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Affiliation(s)
- N Minami
- The 2nd Department of Internal Medicine, Mie University School of Medicine, Tsu, Japan
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Williams SB, McKeown LP, Krutzsch H, Hansmann K, Gralnick HR. Purification and characterization of human platelet von Willebrand factor. Br J Haematol 1994; 88:582-91. [PMID: 7819071 DOI: 10.1111/j.1365-2141.1994.tb05077.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Platelet von Willebrand factor (vWf) was purified from human platelet concentrates. The multimeric structure of the purified platelet vWf was similar to that observed in the initial platelet lysate, and, like the platelet lysate, the purified platelet vWf contained higher molecular weight multimers than plasma vWf. The apparent molecular weight of the reduced platelet vWf subunit was similar to the plasma vWf subunit. The N-terminal amino acid of the purified platelet and plasma vWf was blocked. In concentration dependent binding to botrocetin- or ristocetin-stimulated platelets, 125I-plasma vWf bound with a higher affinity than platelet. The ristocetin cofactor activity per mg of purified plasma vWf was 5-fold greater than the platelet vWf activity. Platelet and plasma vWf bound to collagen with similar affinities; however, platelet vWf bound to thrombin-stimulated platelets and to heparin with a higher affinity than plasma vWf. The differences in the binding affinity(s) of plasma and platelet vWf to platelet GPIb and GPIIb/IIIa and extracellular matrix proteins may reflect different roles for plasma and platelet vWf in the initial stages of haemostasis and thrombosis.
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Affiliation(s)
- S B Williams
- Hematology Service, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
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Uchiyama S, Yamazaki M, Maruyama S, Handa M, Ikeda Y, Fukuyama M, Itagaki I. Shear-induced platelet aggregation in cerebral ischemia. Stroke 1994; 25:1547-51. [PMID: 8042205 DOI: 10.1161/01.str.25.8.1547] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
BACKGROUND AND PURPOSE Recent evidence has suggested that shear-induced platelet aggregation is an important mechanism of thrombosis at arterial bifurcations or stenoses. We measured shear-induced platelet aggregation with a new apparatus in patients with cerebral ischemia and also studied correlations with other hemostatic parameters as well as the effect of antiplatelet agents. METHODS The subjects were 75 patients with cerebral ischemia and 26 control subjects. Platelet aggregation was induced in citrated platelet-rich plasma by a high shear stress (108 dynes/cm2) that was applied by means of a cone-plate streaming chamber based on turbidimetry. We studied the correlation of test results with hemostatic parameters and also the effects of antiplatelet agents. RESULTS Compared with the control subjects, an increase of shear-induced platelet aggregation was observed in 21 patients with atherothrombotic stroke and 12 with transient ischemic attacks, but not in 11 with cardioembolic stroke or 31 with lacunar stroke. There was no significant correlation of shear-induced platelet aggregation with platelet count, agonist-induced platelet aggregation, fibrinogen level, or beta-thromboglobulin level. The extent of shear-induced aggregation was not correlated with von Willebrand factor antigen levels but was significantly correlated with the amounts of larger von Willebrand factor multimers. Oral aspirin (81 mg/d) did not inhibit shear-induced platelet aggregation, whereas oral ticlopidine (200 mg/d) significantly inhibited it. CONCLUSIONS These results indicate that shear-induced platelet aggregation is increased in patients with atherothrombotic stroke and transient ischemic attacks, is correlated with the increase of larger von Willebrand factor multimers, and is corrected by ticlopidine but not by low-dose aspirin.
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Affiliation(s)
- S Uchiyama
- Department of Neurology, Tokyo Women's Medical College, Japan
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Hawiger J, Timmons S. Binding of fibrinogen and von Willebrand factor to platelet glycoprotein IIb-IIIa complex. Methods Enzymol 1992; 215:228-43. [PMID: 1435324 DOI: 10.1016/0076-6879(92)15067-m] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- J Hawiger
- Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
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Functional analysis of a recombinant glycoprotein Ib alpha polypeptide which inhibits von Willebrand factor binding to the platelet glycoprotein Ib-IX complex and to collagen. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)48430-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Affiliation(s)
- H J Weiss
- Department of Medicine, St. Luke's-Roosevelt Hospital Center, New York, New York
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Gartner TK, Taylor DB. The amino acid sequence Gly-Ala-Pro-Leu appears to be a fibrinogen binding site in the platelet integrin, glycoprotein IIb. Thromb Res 1990; 60:291-309. [PMID: 1708172 DOI: 10.1016/0049-3848(90)90108-o] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The amino acid sequence Gly-Ala-Pro-Leu-Arg-Val is predicted by the anticomplementarity hypothesis to be a fibrinogen binding site on human platelet fibrinogen receptors. The peptide Ala-Pro-Leu-Arg-Val binds fibrinogen and inhibits platelet aggregation and clot retraction. The peptide Gly-Ala-Pro-Leu is the shortest sequence within the predicted sequence which potently inhibits the adhesion of platelets to fibrinogen and platelet aggregation. The sequence Gly-Ala-Pro-Leu is present as residues 309-312 in glycoprotein IIb, the alpha-subunit of the glycoprotein IIb/IIIa complex, the fibrinogen receptor. The sequence Gly-Ala-Pro-Leu is present in 4 of 8 integrin alpha-subunits and Gly-Ala-Pro is present in 8 of 8 integrin alpha-subunits.
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Affiliation(s)
- T K Gartner
- Department of Biology, Memphis State University, TN 38152
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Piétu G, Meulien P, Cherel G, Diaz J, Baruch D, Courtney M, Meyer D. Production in Escherichia coli of a biologically active subfragment of von Willebrand factor corresponding to the platelet glycoprotein Ib, collagen and heparin binding domains. Biochem Biophys Res Commun 1989; 164:1339-47. [PMID: 2686638 DOI: 10.1016/0006-291x(89)91816-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A full-length cDNA for vWF has been cloned from a human lung cDNA library and a fragment of this cDNA has been modified to allow its expression in E. coli. This fragment, which corresponds to Val 449-Asn 730 of vWF and includes the GPIb-binding domain and binding sites for collagen and heparin, was subcloned into an expression vector containing an inducible lambda PL promoter. On induction, the expressed recombinant vWF subfragment migrated with a mol wt of around 38,000 after SDS-PAGE. It was identified as a vWF fragment by Western blotting using either a polyclonal or a monoclonal antibody which inhibits the binding of vWF to GPIb. Following solubilization in urea, the bacterial extract inhibited ristocetin-induced platelet aggregation and bound to ristocetin-treated platelets, to collagen and to heparin.
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Affiliation(s)
- G Piétu
- INSERM U. 143, Hôpital de Bicêtre, le Kremlin Bicêtre, France
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Baruch D, Bahnak B, Girma JP, Meyer D. von Willebrand factor and platelet function. BAILLIERE'S CLINICAL HAEMATOLOGY 1989; 2:627-72. [PMID: 2673431 DOI: 10.1016/s0950-3536(89)80037-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
vWF is an adhesive protein that binds to two distinct platelet glycoproteins, GP Ib and GP IIb-IIa complex. Its interaction with GP Ib is primarily responsible for platelet adhesion to the subendothelium. The current model is that vWF binds to collagen and/or another component of the subendothelium, after which a conformational change in the vWF molecule exposes the GP Ib binding site. This interaction may not only promote the initial attachment of platelets to the subendothelium but also play a role in thrombus formation through exposure of GP IIb-IIIa to which vWF and fibrinogen can bind. The second important function of vWF is to be a carrier for F. VIII, protecting it from degradation and playing a role in its activation by thrombin. Circulating vWF has a complex multimeric structure that ranges in Mrs from 0.5 to 20 x 10(6) Daltons. The basic subunit has a Mr of 270 kDa. Amino acid sequencing of vWF demonstrated that the basic subunit or mature vWF is made up of 2050 amino acids. Molecular cloning of the vWF cDNA revealed that the primary transcript consists of 8900 base pairs that encode for 2813 amino acids, including a 22 amino acid signal peptide and a propolypeptide of 741 amino acids, called vWF antigen II. Recent studies on the expression of recombinant vWF molecules indicate that the propolypeptide is involved in the multimerization of vWF. The domains on the vWF molecule involved in the interactions of vWF with GP Ib, GP IIb-IIIa, collagen, F. VIII and heparin have been localized to varying extents. It is anticipated that peptide analysis and recombinant DNA techniques, such as in vitro mutagenesis, will further define the structural requirements of these binding domains. vWF is synthesized in a cell-specific manner by endothelial cells and megakaryocytes. It undergoes a complex intracellular biosynthesis involving transcription of a 200 kb gene, splicing out more than 42 introns, translation of a 8900 bp mRNA, glycosylation, disulphide bond formation, sulphatation, multimerization and proteolytic cleavage. The molecule can be secreted in a constitutive or regulated manner upon perturbation of the endothelial cells with physiological and non-physiological secretagogues. The mechanisms that control the synthesis of vWF should be an exciting area of further research. vWD is probably the most common of all congenital disorders of haemostasis. It is an extremely heterogeneous syndrome involving quantitative or qualitative disorders of vWF.(ABSTRACT TRUNCATED AT 400 WORDS)
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Mcgregor L, Smith AD, Sidey M, Belin J, Zilkha KJ, McGregor JL. Effects of dietary linoleic acid and gamma linolenic acid on platelets of patients with multiple sclerosis. Acta Neurol Scand 1989; 80:23-7. [PMID: 2782038 DOI: 10.1111/j.1600-0404.1989.tb03837.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The effects of dietary evening primrose oil (rich in linoleic acid and gamma-linolenic acid) were studied on platelets of multiple sclerosis (MS) patients and controls. It was found that platelet aggregation (ADP, thrombin and collagen), platelet fibrinogen binding and platelet glycoprotein (sialic acid and N-acetyl glucosamine) content were not significantly modified by evening primrose oil in MS patients and controls. Moreover, platelet fibrinogen binding and platelet glycoprotein (sialic acid and N-acetyl glucosamine) content were determined for the first time in MS patients and found similar to controls. Platelets of MS patients aggregated more to thrombin and collagen compared to controls, but the difference was only significant with thrombin aggregation after the oil treatment. This study does not show a significant effect of evening primrose oil on platelets of MS patients.
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Affiliation(s)
- L Mcgregor
- Inserm Unit 63, Alexis Carrel Medical School, Lyon, France
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Tranqui L, Andrieux A, Hudry-Clergeon G, Ryckewaert JJ, Soyez S, Chapel A, Ginsberg MH, Plow EF, Marguerie G. Differential structural requirements for fibrinogen binding to platelets and to endothelial cells. J Cell Biol 1989; 108:2519-27. [PMID: 2738096 PMCID: PMC2115601 DOI: 10.1083/jcb.108.6.2519] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The cytoadhesins represent a group of RGD receptors that belongs to the integrin superfamily of adhesion molecules. Members of this cytoadhesin family include the platelet GPIIb-IIIa and the vitronectin receptors. These glycoproteins share the same beta-subunit, which is associated with different alpha subunits to form an alpha/beta heterodimer. In the present study, we have analyzed the fine recognition specificy of the cytoadhesins from platelets and endothelial cells for the adhesive protein, fibrinogen. Two sets of synthetic peptides, RGDX peptides and peptides corresponding to the COOH terminus of the fibrinogen gamma chain, were compared for their structure-function relationships in the two cellular systems. The results indicate that: (a) both RGDX and gamma-chain peptides inhibit the binding of fibrinogen to platelets and endothelial cells; (b) a marked influence of the residue at the COOH- and NH2-terminal positions of each peptide set can be demonstrated on the two types; and (c) RGDX and gamma peptides have differential effects on platelets and endothelial cells with respect to fine structural requirements. These results clearly indicate that while the platelet and endothelial cytoadhesins may interact with similar peptidic sequences, they express a different fine structural recognition.
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Affiliation(s)
- L Tranqui
- DRF/Laboratoire d'Hématologie, Unité INSERM 217, Grenoble, France
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Santoro SA, Lawing WJ. Modulation of an RGDS binding site on the platelet membrane glycoprotein IIb-IIIa complex. Biochem Biophys Res Commun 1989; 160:189-95. [PMID: 2712830 DOI: 10.1016/0006-291x(89)91639-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Fibronectin, von Willebrand factor, and fibrinogen each bind to the glycoprotein IIb-IIIa complex on activated platelets via an arg-gly-asp-ser (RGDS) sequence present within the adhesive proteins. Both the IIb and IIIa polypeptides of the IIb-IIIa complex on thrombin activated platelets are specifically and extensively labeled by a radiolabeled, photoactivatable arylazide derivative of the RGDS sequence when the labeling is performed in the presence of concentrations of Ca++ or Mg++ approaching 0.5 mM. In contrast, labeling of unactivated platelets, ADP activated platelets, or thrombin activated platelets in the presence of low concentrations of divalent cations resulted in restriction of labeling to the IIb polypeptide of the complex.
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Affiliation(s)
- S A Santoro
- Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110
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25
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Weiss HJ, Hawiger J, Ruggeri ZM, Turitto VT, Thiagarajan P, Hoffmann T. Fibrinogen-independent platelet adhesion and thrombus formation on subendothelium mediated by glycoprotein IIb-IIIa complex at high shear rate. J Clin Invest 1989; 83:288-97. [PMID: 2910912 PMCID: PMC303673 DOI: 10.1172/jci113871] [Citation(s) in RCA: 193] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Platelet adhesion and thrombus formation on subendothelium, studied at a shear rate of 2,600 s-1, were inhibited by two synthetic peptides known to interact with GPIIb-IIIa. One peptide (HHLGGAKQAGDV) corresponds to the carboxyl terminal segment of the fibrinogen gamma-chain (gamma 400-411) and the other (RGDS) contains the amino acid sequence Arg-Gly-Asp (RGD) common to fibronectin, von Willebrand factor, vitronectin and the alpha-chain of fibrinogen. Neither platelet adhesion nor thrombus formation were decreased in a patient with severe congenital fibrinogen deficiency and this was equally true when his blood was further depleted of the small amounts of fibrinogen present utilizing an anti-fibrinogen antibody. In normal subjects, adhesion and thrombus formation were inhibited by the Fab' fragments of a monoclonal anti-GPIIb-IIIa antibody (LJ-CP8), which interferes with the interaction of platelets with all four adhesive proteins in both the fluid and solid phase. However, another anti-GPIIb-IIIa antibody (LJ-P5) that had minimal effects on the interaction of platelets with fibrinogen, but inhibited to varying degrees platelet interaction with other adhesive proteins, was equally effective. The findings demonstrate that, at a shear rate of 2,600 s-1, adhesive proteins other than fibrinogen are involved in GPIIb-IIIa-mediated platelet adhesion and thrombus formation on subendothelium. In addition, since LJ-P5 inhibited the binding of soluble von Willebrand factor and vitronectin, these adhesive proteins may be involved in platelet thrombus formation. In contrast to the results obtained at a shear rate of 2,600 s-1, fibrinogen could play a role in mediating platelet-platelet interactions with weak agonists or lower shear rates.
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Affiliation(s)
- H J Weiss
- Department of Medicine, St. Luke's-Roosevelt Hospital Center, New York, New York 10019
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26
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Kunicki TJ, Nugent DJ, Staats SJ, Orchekowski RP, Wayner EA, Carter WG. The human fibroblast class II extracellular matrix receptor mediates platelet adhesion to collagen and is identical to the platelet glycoprotein Ia-IIa complex. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68811-8] [Citation(s) in RCA: 152] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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27
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Hanson SR, Pareti FI, Ruggeri ZM, Marzec UM, Kunicki TJ, Montgomery RR, Zimmerman TS, Harker LA. Effects of monoclonal antibodies against the platelet glycoprotein IIb/IIIa complex on thrombosis and hemostasis in the baboon. J Clin Invest 1988; 81:149-58. [PMID: 2961790 PMCID: PMC442486 DOI: 10.1172/jci113286] [Citation(s) in RCA: 133] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
To assess the hemostatic consequences and antithrombotic effectiveness of blocking the platelet glycoprotein (GP) IIb/IIIa receptor for fibrinogen and other adhesive glycoproteins in vivo, well characterized murine monoclonal antibodies against the platelet GP IIb/IIIa complex, AP-2 and LJ-CP8, were infused intravenously into baboons. Four animals each received doses of 0.2, 0.4, and 1.0 mg/kg of purified AP-2 IgG, and three animals were given 1.0 mg/kg of the F(ab)2 fragment of AP-2. Five additional animals were given 10 mg/kg LJ-CP8 IgG. At the highest dose, radiolabeled AP-2 IgG bound to an average of 33,000 sites on the circulating platelets. Serial measurements included platelet count, bleeding time, platelet aggregation (induced by ADP, collagen, and gamma-thrombin), and 111In-platelet deposition onto Dacron vascular grafts. Bleeding times were markedly prolonged after injection of 1.0 mg/kg AP-2 IgG (19.2 +/- 3.4 min), 1.0 mg/kg AP-2 F(ab)2 (16.5 +/- 1.8 min), and 10 mg/kg LJ-CP8 (greater than 30 min) vs. control studies (4.6 +/- 0.2 min), and remained prolonged for 48 h. With each antibody platelet aggregation was initially reduced or absent, with partial recovery over 48 h in a manner that was inversely related to dose. AP-2, both whole IgG and F(ab)2 fragment, but not LJ-CP8, caused a dose-dependent reduction (20-46%) in the circulating platelet count over 24 h. Neither AP-2 nor LJ-CP8 caused a reduction in intraplatelet platelet factor 4, beta-thromboglobulin, or [14C]serotonin. Graft-associated platelet thrombus formation was reduced by 73% (1.0 mg/kg AP-2 IgG and 10 mg/kg LJ-CP8) and 53% (1.0 mg/kg AP-2 F(ab)2) relative to control values. In contrast, neither heparin (100 U/kg) nor aspirin (32.5 mg/kg twice a day) showed antithrombotic efficacy in this model. Thus, antibodies that functionally alter the platelet GP IIb/IIIa complex may produce immediate, potent, and transient, antihemostatic, and antithrombotic effects.
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Affiliation(s)
- S R Hanson
- Roon Research Center for Arteriosclerosis and Thrombosis, Research Institute of Scripps Clinics, La Jolla, California 92037
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28
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Biosynthetic and functional properties of an Arg-Gly-Asp-directed receptor involved in human melanoma cell attachment to vitronectin, fibrinogen, and von Willebrand factor. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45436-1] [Citation(s) in RCA: 378] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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29
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Mustard JF, Groves HM, Kinlough-Rathbone RL, Packham MA. Thrombogenic and nonthrombogenic biological surfaces. Ann N Y Acad Sci 1987; 516:12-21. [PMID: 3326480 DOI: 10.1111/j.1749-6632.1987.tb33026.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- J F Mustard
- Department of Pathology, McMaster University, Hamilton, Canada
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30
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Zucker MB, Brownlea S, McPherson J. Insights into the mechanism of platelet retention in glass bead columns. Ann N Y Acad Sci 1987; 516:398-406. [PMID: 3501937 DOI: 10.1111/j.1749-6632.1987.tb33058.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- M B Zucker
- Department of Pathology, New York University Medical Center, New York 10016
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31
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Affiliation(s)
- H J Weiss
- Department of Medicine, St. Luke's-Roosevelt Hospital Center, New York, New York 10019
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32
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Abstract
Adhesive molecules are essential for anchoring platelets to the zone of vascular injury and for linking them together. Among adhesive molecules, von Willebrand factor and fibrinogen bind to platelets "on demand" when their membrane receptors, composed of membrane glycoproteins, are transformed into the binding mode. At least one receptor mechanism for fibrinogen and for vWF is controlled by ADP that is secreted through the known pathways of platelet activation and counterbalanced by cyclic AMP. Structural and functional studies of adhesive macromolecules led to delineation of receptor pathways responsible for the interaction of platelets with the injured vessel wall and with each other. Synthetic peptide analogues of platelet receptor recognition domains evolved from these studies as a new class of inhibitors of platelet aggregation.
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Affiliation(s)
- J Hawiger
- Department of Medicine, New England Deaconess Hospital, Boston, Massachusetts 02215
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33
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Meyer D, Fressinaud E, Sakariassen KS, Baumgartner HR, Girma JP. Role of von Willebrand factor in platelet vessel-wall interactions. Ann N Y Acad Sci 1987; 509:118-30. [PMID: 3322130 DOI: 10.1111/j.1749-6632.1987.tb30989.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- D Meyer
- INSERM U. 143, Hôpital de Bicêtre, Paris, France
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Chen CS, Thiagarajan P, Schwartz SM, Harlan JM, Heimark RL. The platelet glycoprotein IIb/IIIa-like protein in human endothelial cells promotes adhesion but not initial attachment to extracellular matrix. J Cell Biol 1987; 105:1885-92. [PMID: 2822728 PMCID: PMC2114679 DOI: 10.1083/jcb.105.4.1885] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
On platelets the membrane glycoprotein IIb/IIIa complex (GPIIb/IIIa) functions in adhesive interactions with fibrinogen, von Willebrand factor, and fibronectin. However, the function of GPIIb/IIIa-like proteins on endothelial cells, as well as the ligand(s) the complex binds, is unknown. Using a highly specific polyclonal antibody we have explored the function of GPIIb/IIIa-like proteins on human umbilical vein endothelial cells (HUVE). Analysis by immunoblotting shows that this antiserum recognizes the endothelial GPIIIa-like protein of the complex. The IgG fraction of the polyclonal antiserum and its Fab' fragments detach confluent and subconfluent HUVE from extracellular substrata. The effect of the anti-GPIIb/IIIa IgG is not toxic as the detached cells maintain their viability after trypsinization and replating. Anti-GPIIb/IIIa IgG does not inhibit HUVE binding to extracellular matrix or purified fibronectin in an attachment assay despite the presence of intact GPIIb/IIIa on HUVE detached from substrate by various methods. Apparently, the GPIIb/IIIa-like protein on HUVE is important in normal HUVE adhesion to the extracellular matrix, but it is not required in the initial attachment of HUVE to extracellular matrix.
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Affiliation(s)
- C S Chen
- Department of Medicine, University of Washington, Seattle 98195
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35
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Abstract
Formation of a hemostatic plug represents one of the earliest responses to vessel wall injury. Platelets react to any discontinuity in the vascular endothelium through initial contact, spreading, and formation of a thrombus (or aggregate). This development of a primary hemostatic plug requires platelet membrane receptors through which the adhesive macromolecules, von Willebrand factor (vWF) and fibrinogen, anchor platelets to the vessel wall and link them to each other. There are two receptor pathways--classic and alternative--for the binding of vWF to platelets; the latter induced by thrombin, and adenosine diphosphate (ADP) is shared with fibrinogen. Synthetic peptides, patterned after known binding domains of adhesive molecules, have been designed to inhibit their interactions with platelet receptors. A secondary hemostatic plug, composed of platelets enmeshed in fibrin, results from the action of thrombin, which is not only essential for formation of fibrin but also for exposure of platelet receptors for adhesive molecules and for "activation" of factors V and VIII. Thrombin generation is greatly enhanced through the activity of the prothrombinase complex formed on the surface of platelets, perturbed endothelial cells, and leukocytes. A pivotal event is activation of factor X through the intrinsic and extrinsic coagulation pathways. Binding of factors IXa and VIIa to the vascular endothelium represents a localized mechanism for factor Xa generation. Formation of a platelet and fibrin thrombus is controlled by regulatory mechanism: prostacyclin, endogenous heparin-antithrombin III complex, thrombomodulin-protein C-protein S system, and the fibrinolytic system. The balance of all components--vessel wall, platelets, adhesive and coagulation proteins, regulatory mechanisms--determines the effectiveness of the hemostatic plug in maintaining the structural and functional integrity of the circulatory system. An approach to detection of hemostatic derangements in patients at risk evolves from a full understanding of inherited and acquired deficiencies affecting each step of hemostatic plug formation and from selective use of laboratory tests.
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Loscalzo J, Inbal A, Handin RI. von Willebrand protein facilitates platelet incorporation in polymerizing fibrin. J Clin Invest 1986; 78:1112-9. [PMID: 3489737 PMCID: PMC423774 DOI: 10.1172/jci112668] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
von Willebrand protein was found to promote the incorporation of platelets into evolving fibrin thrombi. Using formalin-treated or fresh platelets, both the initial rate and extent of platelet incorporation into polymerizing fibrin were dependent on von Willebrand protein. von Willebrand protein was incorporated into evolving fibrin thrombi in parallel with platelets. Soluble fibrin monomer covalently linked to acrylonitrile beads (Matrex 102) bound von Willebrand protein specifically and saturably with an apparent approximate dissociation constant (KD) of 15 micrograms/ml. Glycocalicin, the water-soluble proteolytic fragment of glycoprotein Ib, bound to fibrin monomer in this system specifically and saturably, as well, with an apparent approximate KD of 5 micrograms/ml, but only in the presence of saturating concentrations of von Willebrand protein. These data demonstrate that the initial rate and extent of platelet incorporation into evolving fibrin thrombi are dependent on von Willebrand protein; von Willebrand protein serves as a link between polymerizing fibrin and platelet surface glycoprotein Ib; and von Willebrand protein binds to fibrin monomer and is thereby able to bind to platelet surface glycoprotein Ib in the absence of ristocetin.
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37
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McGregor JL, McGregor L, Bauer AS, Catimel B, Brochier J, Dechavanne M, Clemetson KJ. Identification of two distinct regions within the binding sites for fibrinogen and fibronectin on the IIb-IIIa human platelet membrane glycoprotein complex by monoclonal antibodies P2 and P4. EUROPEAN JOURNAL OF BIOCHEMISTRY 1986; 159:443-9. [PMID: 2944746 DOI: 10.1111/j.1432-1033.1986.tb09906.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The effect of two monoclonal antibodies P2 (LyP 2) or P4 (LyP 4), specific for the platelet membrane glycoprotein IIb/IIIa complex, on binding of 125I-labelled fibrinogen or 125I-labelled fibronectin to thrombin-stimulated platelets was studied. These monoclonal antibodies are directed against different determinants on the IIb-IIIa complex and react only with the complex and not with the individual glycoproteins. Fibrinogen binding to thrombin-stimulated platelets was significantly inhibited by P2 but not by P4. Fibronectin binding to thrombin-stimulated platelets was significantly inhibited by P4 but only poorly by P2. These results indicate the presence of specific regions on the glycoprotein IIb-IIIa complex which act as binding sites for fibrinogen or fibronectin. Other authors [Haverstick et al. (1985) Blood 66, 946-952; Ginsberg et al. (1985) J. Biol. Chem. 260, 4133-4138] have shown that a tetrapeptide, Arg-Gly-Asp-Ser, inhibited the binding of fibrinogen, fibronectin, and von Willebrand factor (vWf) to stimulated platelets and that fibrinogen competes with vWf and fibronectin for binding. These findings, together with previous studies, therefore indicate the presence of specific regions as well as a common region in the binding sites for fibrinogen and fibronectin on the IIb-IIIa complex.
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38
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Santoro SA. Identification of a 160,000 dalton platelet membrane protein that mediates the initial divalent cation-dependent adhesion of platelets to collagen. Cell 1986; 46:913-20. [PMID: 3757029 DOI: 10.1016/0092-8674(86)90073-5] [Citation(s) in RCA: 290] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Platelets initially adhere to collagen via a divalent cation-dependent process supported by Mg2+, Mn2+, Fe2+, Cu2+, Zn2+, or Co2+ more rapidly and to a greater extent than by previously studied divalent cation-independent mechanisms. Ca2+ not only fails to support adhesion, it is inhibitory. Platelet activation and secretion are not required for adhesion by this mechanism. Monomeric and fibrillar collagens, but not denatured collagen, effectively support divalent cation-dependent adhesion. Types I, III, and IV collagen, but not type V collagen, support adhesion. A platelet surface protein of Mr 160,000, possibly identical with platelet membrane glycoprotein Ia, that binds to collagen with the appropriate divalent cation specificity has been identified and is the likely mediator of the initial divalent cation-dependent adhesion of platelets to collagen.
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39
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Kupinski JM, Miller JL. Synthesis by guinea pig megakaryocytes of platelet glycoprotein receptors for fibrinogen and von Willebrand factor. Thromb Res 1986; 43:345-52. [PMID: 3016945 DOI: 10.1016/0049-3848(86)90154-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In the preceding paper, we described two monoclonal antibodies, PG-1 and PG-2, that selectively blocked the binding of von Willebrand factor (PG-1) or of fibrinogen (PG-2) to guinea pig platelets. In this study we examine the structures and site of synthesis of these receptors. NP-40 lysates of radiolabeled guinea pig platelets were immunoprecipitated with monoclonal antibodies PG-1 or PG-2, and the precipitates analyzed by SDS-PAGE. PG-1 recognized a single polypeptide with reduced Mr of 143,000 daltons, while PG-2 precipitated two chains with reduced Mr of 121,000 and 93,000 daltons. Periodate-[3H]borohydride labeling of platelets, in conjunction with two-dimensional SDS-PAGE, showed that all three of the polypeptides are glycoproteins and that the 143,000 and 121,000 dalton chains are linked by disulfide bond(s) to smaller, approximately 25,000 dalton polypeptides. Guinea pig megakaryocytes synthesized polypeptides immunoprecipitable by PG-1 and PG-2, with molecular weights similar to polypeptides found associated with platelet membranes. These studies demonstrate that guinea pig platelets have functional receptors for fibrinogen and von Willebrand factor that are structurally homologous to human platelet glycoproteins Ib, IIb and IIIa, and that these glycoproteins are synthesized by megakaryocytes.
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40
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Kupinski JM, Miller JL. Identification of receptors for fibrinogen and von Willebrand factor mediating aggregation in guinea pig platelets. Thromb Res 1986; 43:335-44. [PMID: 3016944 DOI: 10.1016/0049-3848(86)90153-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Monoclonal antibodies were prepared to guinea pig platelets and selected for their ability to inhibit ADP-induced platelet aggregation and ristocetin induced, Ca++-independent platelet agglutination. One antibody, PG-2, produced strong inhibition of aggregation induced by ADP, thrombin, collagen and arachidonic acid, while not inhibiting ristocetin-induced agglutination. A second antibody, PG-1, blocked ristocetin-induced agglutination, but did not inhibit aggregation induced by the previous agents. PG-2 blocked ADP-induced 125I-fibrinogen binding to washed guinea pig platelets by approximately 50%, but did not inhibit ristocetin-induced binding of 125I-vWF. Conversely, PG-1 selectively inhibited ristocetin-induced 125I-vWF binding, with the degree of inhibition inversely related to the ristocetin concentration. These studies suggest that in guinea pig platelets, fibrinogen and von Willebrand factor binding to different membrane sites are responsible for the aggregation response of stimulated platelets and the ristocetin-induced agglutination response respectively. These antibodies offer significant promise for the further development of a guinea pig animal model for studying platelet and megakaryocyte function.
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41
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Furlan M. Factor VIII/von Willebrand factor: a multivalent ligand binding to platelets and collagen. BLUT 1986; 52:329-36. [PMID: 2941086 DOI: 10.1007/bf00320779] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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De Marco L, Girolami A, Zimmerman TS, Ruggeri ZM. von Willebrand factor interaction with the glycoprotein IIb/IIa complex. Its role in platelet function as demonstrated in patients with congenital afibrinogenemia. J Clin Invest 1986; 77:1272-7. [PMID: 3007578 PMCID: PMC424474 DOI: 10.1172/jci112430] [Citation(s) in RCA: 124] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
We have studied three afibrinogenemic patients, who had only trace amounts of plasma and platelet fibrinogen as measured by radioimmunoassay, and demonstrate here that the residual aggregation observed in their platelet-rich plasma is dependent upon von Willebrand factor (vWF) binding to the platelet membrane glycoprotein (GP)IIb/IIIa complex. The abnormality of aggregation was more pronounced when ADP, rather than thrombin, collagen, or the combination of ADP plus adrenaline was used to stimulate platelets. With all stimuli, nevertheless, the platelet response was completely inhibited by a monoclonal antibody (LJP5) that is known to block vWF, but not fibrinogen binding to GPIIb/IIIa. Addition of purified vWF to the afibrinogenemic plasma resulted in marked increase in the rate and extent of aggregation, particularly when platelets were stimulated with ADP. This response was also completely blocked by LJP5. Addition of fibrinogen, however, restored normal aggregation even in the presence of LJP5, a finding consistent with the knowledge that antibody LJP5 has no effect on platelet aggregation mediated by fibrinogen binding to GPIIb/IIIa. Two patients gave their informed consent to receiving infusion of 1-desamino-8-D-arginine vasopressin (DDAVP), a vasopressin analogue known to raise the vWF levels in plasma by two- to fourfold. The bleeding time, measured before and 45 min after infusion, shortened from greater than 24 min to 12 min and 50 s in one patient and from 16 min to 9 min and 30 s in the other. Concurrently, the rate and extent of ADP-induced platelet aggregation improved after DDAVP infusion. The pattern, however, reversed to baseline levels within 4 h. The concentration of plasma vWF increased after DDAVP infusion, but that of fibrinogen remained at trace levels. We conclude that vWF interaction with GPIIb/IIIa mediates platelet-platelet interaction and may play a role in primary hemostasis.
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44
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Bockenstedt P, Greenberg JM, Handin RI. Structural basis of von Willebrand factor binding to platelet glycoprotein Ib and collagen. Effects of disulfide reduction and limited proteolysis of polymeric von Willebrand factor. J Clin Invest 1986; 77:743-9. [PMID: 2936763 PMCID: PMC423458 DOI: 10.1172/jci112369] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
von Willebrand factor (vWF) is a large, multimeric glycoprotein that helps platelets adhere to vascular subendothelium. Although vWF binding to platelet receptors and connective tissue constituents is of fundamental importance in adhesion, there is little information regarding the nature of these vWF binding sites. In this paper, we have compared the structural requirements for vWF binding with platelet glycoprotein Ib (GpIb), heparin, and collagen and have shown that fragments derived from large vWF multimers retain biologic activity. We have shown that a 440,000-D subunit produced by disulfide reduction and alkylation of vWF polymer binds to platelet GpIb. When analyzed by polyacrylamide gel electrophoresis and Sepharose CL6B chromatography, the 440,000-D vWF oligomer is a dimer of the 220,000 subunit of fully reduced native vWF. This vWF dimer competes with 125I-vWF for binding to GpIb with an IC50 of 100 micrograms/ml (227 nM). The GpIb binding domain on vWF was further localized by digestion of native vWF polymers with Staphylococcal V8 protease. A 285,000-D fragment of vWF multimer was separated from heterogeneous 210,000-225,000-D fragments by its ability to bind to heparin. The 285,000-D fragment that bound to heparin Sepharose was composed of two disulfide-linked 175,000- and 115,000-D polypeptides. The heterogeneous fragments contained disulfide-linked 96,000, 66,000, and 53,000-D polypeptides when analyzed on polyacrylamide gel electrophoresis. The 285,000-D fragment competed with 125I-vWF for binding to GpIb with an IC50 of 22 micrograms/ml (77 nM), while the other fragments did not compete for binding. Neither the vWF dimer nor the proteolytic fragments competed with native 125I-vWF polymer for binding to collagen.
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45
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Hamer RJ, Houdijk WP, Sixma JJ. The physiology and pathophysiology of the factor VIII complex. Crit Rev Oncol Hematol 1986; 6:19-54. [PMID: 3096583 DOI: 10.1016/s1040-8428(86)80046-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The factor VIII complex consists of two noncovalently linked proteins: von Willebrand factor (VWF) and factor VIII (FVIII). VWF plays an important role in primary hemostasis by mediating the adherence of blood platelets to the damaged vessel wall. A review of the literature on VWF is given with regard to its physicochemical properties and mode of action. FVIII acts as a cofactor in the factor Xa-generating enzyme complex of the intrinsic coagulation cascade. Starting with the recently published primary structure of FVIII, the literature is reviewed for structural information on FVIII. Also, an effort is made to characterize the interaction of FVIII with VWF and to discuss the possible physiological significance of FVIII-VWF complex formation. Interaction of FVIII with the clotting factors of the intrinsic pathway of coagulation is described in detail. Hemophilia and von Willebrand's disease (VWD) are both congenital bleeding disorders affecting a great many people. The different variants of these diseases are described with some reference to therapy and detection.
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46
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Plow EF, Pierschbacher MD, Ruoslahti E, Marguerie GA, Ginsberg MH. The effect of Arg-Gly-Asp-containing peptides on fibrinogen and von Willebrand factor binding to platelets. Proc Natl Acad Sci U S A 1985; 82:8057-61. [PMID: 3877935 PMCID: PMC391441 DOI: 10.1073/pnas.82.23.8057] [Citation(s) in RCA: 414] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The Arg-Gly-Asp sequence resides in the cell attachment region of fibronectin. Arg-Gly-Asp-containing peptides support fibroblast attachment, inhibit fibroblast adhesion to fibronectin, and inhibit fibronectin binding to thrombin-stimulated platelets. In view of the similarities between the binding of fibronectin, fibrinogen, and von Willebrand factor to stimulated platelets, we have examined the effects of Arg-Gly-Asp-containing peptides on the interaction of these latter two adhesive proteins with platelets. Gly-Arg-Gly-Asp-Ser-Pro was used as a prototype peptide, and this hexapeptide inhibited fibrinogen binding to ADP and thrombin-stimulated platelets in the 10-200 microM range. The inhibition exceeded 90% at high concentrations of peptide and was observed in the presence of either calcium or magnesium. Platelet aggregation was also inhibited by the peptide in this dose range. The hexapeptide inhibited fibrinogen binding to platelets with receptors fixed in an exposed state, indicating direct interference with the ligand-platelet interaction. The peptide was 1/2 to 1/3rd as potent in inhibiting fibrinogen as fibronectin binding to platelets, but fibrinogen and von Willebrand factor binding were inhibited to an identical extent. Conservative amino acid substitutions for the arginine, glycine, or aspartic acid markedly reduced inhibitory activity and the Asp-Gly-Arg sequence was inactive. These results indicate that Arg-Gly-Asp-containing peptides can inhibit the binding of the three adhesive proteins to stimulated platelets, establishing a basic common feature between the interaction of these molecules with platelets.
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Lombardo VT, Hodson E, Roberts JR, Kunicki TJ, Zimmerman TS, Ruggeri ZM. Independent modulation of von Willebrand factor and fibrinogen binding to the platelet membrane glycoprotein IIb/IIIa complex as demonstrated by monoclonal antibody. J Clin Invest 1985; 76:1950-8. [PMID: 2414325 PMCID: PMC424250 DOI: 10.1172/jci112193] [Citation(s) in RCA: 76] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
In this study we have used two new monoclonal antibodies, designated LJP5 and LJP9, as well as a previously described one, AP2, all specific for the platelet membrane glycoprotein (GP)IIb/IIIa complex. None of them reacted with dissociated GPIIb or GPIIIa. The monovalent Fab fragment of both LJP5 and LJP9 bound to unstimulated platelets in a saturable manner, but binding was markedly decreased after platelets had been incubated at 37 degrees C in the absence of added extracellular calcium. The binding of LJP9 was not affected by AP2, but was blocked by excess LJP5. On the contrary, the binding of LJP5 was blocked in the presence of both AP2 and LJP9. Thus, these antibodies bound to distinct epitopes of GPIIb/IIIa. At saturation, the binding to unstimulated platelets was between 2.41 and 10.9 X 10(4) molecules/platelet for LJP5 and between 3.47 and 9.1 X 10(4) molecules/platelet for LJP9 (range of 11 and 10 experiments, respectively). Binding increased up to 50% after thrombin stimulation. The estimated association constant, Ka, was 2.7 X 10(7) M-1 for LJP5 and 3.85 X 10(7) M-1 for LJP9. Both LJP5 and LJP9 partially inhibited the association of 45Ca2+ with the surface of unstimulated platelets. Moreover, both antibodies blocked the binding of von Willebrand factor (vWF) to stimulated platelets, whereas only LJP9, but not LJP5, blocked fibrinogen binding. LJP9 was also a potent inhibitor of platelet aggregation, whereas LJP5 was without effect in this regard. The results of the present study demonstrate that independent modulation of vWF and fibrinogen binding to stimulated platelets can be attained with monoclonal antibodies directed against distinct epitopes of GPIIb/IIIa.
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Holmberg L, Kristoffersson AC, Lamme S, Nilsson IM, Awidi A, Solum NO. Platelet--von Willebrand factor interactions in type IIB von Willebrand's disease. SCANDINAVIAN JOURNAL OF HAEMATOLOGY 1985; 35:305-14. [PMID: 3877338 DOI: 10.1111/j.1600-0609.1985.tb01710.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Type IIB von Willebrand's disease (vWD) is a distinct form of this disorder in which the largest multimers of the von Willebrand factor (vWF) are lacking in plasma but present in platelets. When the vasopressin analogue, 1-deamino-8-D-arginine vasopressin (DDAVP), is given to patients with type IIB vWD, an abnormal vWF is released to plasma. This vWF causes thrombocytopenia in vivo and platelet aggregation in vitro. Aggregation occurs in the plasma milieu and thus at physiological fibrinogen concentration. In this study we demonstrate that IIB post-DDAVP vWF aggregated only metabolically active platelets. The platelet aggregation was completely inhibited by EDTA and PGE1, and either inhibited or greatly weakened by ASA, demonstrating the role of divalent cations and thromboxane A2 formation. In spite of inhibiting platelet aggregation, EDTA, PGE1 and ASA did not prevent platelet binding of IIB post-DDAVP vWF. An antiserum against GP Ib made normal platelets less responsive to the IIB vWF although neither platelet aggregation nor vWF binding were completely prevented. The aggregation was fibrinogen-dependent and platelets from patients with Glanzmann's thrombasthenia were unresponsive. The studies provide evidence that IIB post-DDAVP vWF is bound to unstimulated platelets and that the interaction between vWF and platelets in type IIB vWD is different from ristocetin-induced as well as thrombin- and epinephrine-induced binding to platelets of normal vWF.
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Abstract
Von Willebrand factor (vWF) is a glycoprotein that appears to play a major role in subserving the adhesion of platelets to subendothelium during hemostasis. Endothelial cells have been shown capable of synthesizing and releasing this large, multimeric glycoprotein that normally circulates in the plasma in association with the factor VIII coagulant molecule. Megakaryocytes, the precursor cells of blood platelets, also appear to possess vWF biosynthetic capacity, since cultured guinea pig megakaryocytes have been shown to produce a polypeptide precipitable by antibody to vWF. We now report a study of the multimeric structure of vWF in the megakaryocyte, as well as a quantitative comparison of megakaryocyte vWF with that of platelets and plasma in the guinea pig. Multimeric analysis on SDS agarose gels employing 125I-emu anti-human vWF revealed striking homology between human and guinea pig vWF. Platelets and megakaryocytes from the same guinea pigs contained vWF of highly comparable multimeric composition. Moreover, megakaryocytes and platelets both contained a subset of very high molecular weight multimers not present in plasma. Quantitation of vWF in megakaryocytes and platelets was achieved with a radioimmunoassay performed on detergent (NP-40) lysates of washed cells. These measurements showed that megakaryocytes and platelets contain 0.079 and 0.069 U of vWF per mg protein, respectively. The results of these studies suggest that megakaryocytes represent the primary, if in fact not sole, source of platelet vWF.
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