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Gremmel T, Frelinger AL, Michelson AD. Platelet Physiology. Semin Thromb Hemost 2024. [PMID: 38653463 DOI: 10.1055/s-0044-1786387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Platelets are the smallest blood cells, numbering 150 to 350 × 109/L in healthy individuals. The ability of activated platelets to adhere to an injured vessel wall and form aggregates was first described in the 19th century. Besides their long-established roles in thrombosis and hemostasis, platelets are increasingly recognized as pivotal players in numerous other pathophysiological processes including inflammation and atherogenesis, antimicrobial host defense, and tumor growth and metastasis. Consequently, profound knowledge of platelet structure and function is becoming more important in research and in many fields of modern medicine. This review provides an overview of platelet physiology focusing particularly on the structure, granules, surface glycoproteins, and activation pathways of platelets.
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Affiliation(s)
- Thomas Gremmel
- Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts
- Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria
- Institute of Cardiovascular Pharmacotherapy and Interventional Cardiology, Karl Landsteiner Society, St. Pölten, Austria
- Karl Landsteiner University of Health Sciences, Krems, Austria
- Department of Internal Medicine I, Cardiology and Intensive Care Medicine, Landesklinikum Mistelbach-Gänserndorf, Mistelbach, Austria
| | - Andrew L Frelinger
- Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts
| | - Alan D Michelson
- Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts
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2
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Wang X, Slater A, Lee SC, Harrison N, Pollock NL, Bakker SE, Navarro S, Nieswandt B, Dafforn TR, García Á, Watson SP, Tomlinson MG. Purification and characterisation of the platelet-activating GPVI/FcRγ complex in SMALPs. Arch Biochem Biophys 2024; 754:109944. [PMID: 38395124 DOI: 10.1016/j.abb.2024.109944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 02/13/2024] [Accepted: 02/20/2024] [Indexed: 02/25/2024]
Abstract
The collagen/fibrin(ogen) receptor, glycoprotein VI (GPVI), is a platelet activating receptor and a promising anti-thrombotic drug target. However, while agonist-induced GPVI clustering on platelet membranes has been shown to be essential for its activation, it is unknown if GPVI dimerisation represents a unique conformation for ligand binding. Current GPVI structures all contain only the two immunoglobulin superfamily (IgSF) domains in the GPVI extracellular region, so lacking the mucin-like stalk, transmembrane, cytoplasmic tail of GPVI and its associated Fc receptor γ (FcRγ) homodimer signalling chain, and provide contradictory insights into the mechanisms of GPVI dimerisation. Here, we utilised styrene maleic-acid lipid particles (SMALPs) to extract GPVI in complex with its two associated FcRγ chains from transfected HEK-293T cells, together with the adjacent lipid bilayer, then purified and characterised the GPVI/FcRγ-containing SMALPs, to enable structural insights into the full-length GPVI/FcRγ complex. Using size exclusion chromatography followed by a native polyacrylamide gel electrophoresis (PAGE) method, SMA-PAGE, we revealed multiple sizes of the purified GPVI/FcRγ SMALPs, suggesting the potential existence of GPVI oligomers. Importantly, GPVI/FcRγ SMALPs were functional as they could bind collagen. Mono-dispersed GPVI/FcRγ SMALPs could be observed under negative stain electron microscopy. These results pave the way for the future investigation of GPVI stoichiometry and structure, while also validating SMALPs as a promising tool for the investigation of human membrane protein interactions, stoichiometry and structure.
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Affiliation(s)
- Xueqing Wang
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK; Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK; Centre for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade de Santiago de Compostela, and Instituto de Investigación Sanitaria de Santiago (IDIS), 15782 Santiago de Compostela, Spain.
| | - Alexandre Slater
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK; Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK
| | - Sarah C Lee
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Neale Harrison
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Naomi L Pollock
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Saskia E Bakker
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Stefano Navarro
- Institute of Experimental Biomedicine I, University Hospital Würzburg, Würzburg Josef-Schneider-Straße 2, 97080 Wurzburg, Germany; Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, 97080 Wurzburg, Germany
| | - Bernhard Nieswandt
- Institute of Experimental Biomedicine I, University Hospital Würzburg, Würzburg Josef-Schneider-Straße 2, 97080 Wurzburg, Germany; Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, 97080 Wurzburg, Germany
| | - Tim R Dafforn
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Ángel García
- Centre for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade de Santiago de Compostela, and Instituto de Investigación Sanitaria de Santiago (IDIS), 15782 Santiago de Compostela, Spain
| | - Steve P Watson
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK; Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK
| | - Michael G Tomlinson
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK; Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK.
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3
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Slater A, Khattak S, Thomas MR. GPVI inhibition: Advancing antithrombotic therapy in cardiovascular disease. EUROPEAN HEART JOURNAL. CARDIOVASCULAR PHARMACOTHERAPY 2024:pvae018. [PMID: 38453424 DOI: 10.1093/ehjcvp/pvae018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2024]
Abstract
Glycoprotein (GP) VI plays a major role in thrombosis but not haemostasis, making it a promising antithrombotic target. The primary role of GPVI on the surface of platelets is a signalling receptor for collagen, which is one of the most potent thrombotic sub-endothelial components that is exposed by atherosclerotic plaque rupture. Inhibition of GPVI has therefore been investigated as a strategy for treatment and prevention of atherothrombosis, such as during stroke and acute coronary syndromes. A range of specific GPVI inhibitors have been characterised and 2 of these inhibitors, glenzocimab and revacept, have completed phase II clinical trials in ischemic stroke. In this review, we summarise mechanisms of GPVI activation and the latest progress of clinically tested GPVI inhibitors, including their mechanisms of action. By focussing on what is known about GPVI activation, we also discuss whether alternate strategies could also be used to target GPVI.
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Affiliation(s)
- Alexandre Slater
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Sophia Khattak
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Cardiology Department, Queen Elizabeth Hospital, University Hospitals Birmingham, Birmingham, United Kingdom
| | - Mark R Thomas
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Cardiology Department, Queen Elizabeth Hospital, University Hospitals Birmingham, Birmingham, United Kingdom
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4
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AlOuda SK, Sasikumar P, AlThunayan T, Alaajam F, Khan S, Sahli KA, Abohassan MS, Pollitt A, Jung SM, Gibbins JM. Role of heat shock protein 47 in platelet glycoprotein VI dimerization and signaling. Res Pract Thromb Haemost 2023; 7:102177. [PMID: 37767064 PMCID: PMC10520510 DOI: 10.1016/j.rpth.2023.102177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 09/23/2022] [Accepted: 07/21/2023] [Indexed: 09/29/2023] Open
Abstract
Background Heat shock protein 47 (HSP47) is an intracellular chaperone protein with an indispensable role in collagen biosynthesis in collagen-secreting cells. This chaperone has also been shown to be released and present on the surface of platelets. The inhibition of HSP47 in human platelets or its ablation in mouse platelets reduces platelet function in response to collagen and the glycoprotein (GP) VI collagen receptor agonist CRP-XL. Objectives In this study, we sought, through experiments, to explore cellular distribution, trafficking, and influence on GPVI interactions to understand how HSP47 modulates collagen receptor signaling. Methods HSP47-deficient mouse platelets and SMIH- treated human platelets were used to study the role of HSP47 in collagen mediated responses and signaling. Results Using subcellular fractionation analysis and immunofluorescence microscopy, HSP47 was found to be localized to the platelet-dense tubular system. Following platelet stimulation, HSP47 mobilization to the cell surface was shown to be dependent on actin polymerization, a feature common to other dense tubular system resident platelet proteins that are released to the cell surface during activation. In this location, HSP47 was found to contribute to platelet adhesion to collagen or CRP-XL but not to GFOGER peptide (an integrin α2β1-binding sequence within collagens), indicating selective effects of HSP47 on GPVI function. Dimerization of GPVI on the platelet surface increases its affinity for collagen. GPVI dimerization was reduced following HSP47 inhibition, as was collagen and CRP-XL-mediated signaling. Conclusion The present study identifies a role for cell surface-localized HSP47 in modulating platelet responses to collagen through dimerization of GPVI, thereby enhancing platelet signaling and activation.
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Affiliation(s)
- Sarah K. AlOuda
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Kingdom of Saudi Arabia
| | - Parvathy Sasikumar
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
- Centre for Haematology, Imperial College London, Hammersmith Hospital Campus, London, United Kingdom
| | - Taysseer AlThunayan
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Fahd Alaajam
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
- Department of Medical Laboratory Technology, College of Applied Medical Sciences, Jazan University, Gizan, Saudi Arabia
| | - Sabeeya Khan
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Khaled A. Sahli
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
- General Directorate of Medical Services, Ministry of Interior, Riyadh, Kingdom of Saudi Arabia
| | - Mohammed S. Abohassan
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha, Saudi Arabia
| | - Alice Pollitt
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Stephanie M. Jung
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Jonathan M. Gibbins
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
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5
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Tantiwong C, Dunster JL, Cavill R, Tomlinson MG, Wierling C, Heemskerk JWM, Gibbins JM. An agent-based approach for modelling and simulation of glycoprotein VI receptor diffusion, localisation and dimerisation in platelet lipid rafts. Sci Rep 2023; 13:3906. [PMID: 36890261 PMCID: PMC9994409 DOI: 10.1038/s41598-023-30884-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 03/02/2023] [Indexed: 03/10/2023] Open
Abstract
Receptor diffusion plays an essential role in cellular signalling via the plasma membrane microenvironment and receptor interactions, but the regulation is not well understood. To aid in understanding of the key determinants of receptor diffusion and signalling, we developed agent-based models (ABMs) to explore the extent of dimerisation of the platelet- and megakaryocyte-specific receptor for collagen glycoprotein VI (GPVI). This approach assessed the importance of glycolipid enriched raft-like domains within the plasma membrane that lower receptor diffusivity. Our model simulations demonstrated that GPVI dimers preferentially concentrate in confined domains and, if diffusivity within domains is decreased relative to outside of domains, dimerisation rates are increased. While an increased amount of confined domains resulted in further dimerisation, merging of domains, which may occur upon membrane rearrangements, was without effect. Modelling of the proportion of the cell membrane which constitutes lipid rafts indicated that dimerisation levels could not be explained by these alone. Crowding of receptors by other membrane proteins was also an important determinant of GPVI dimerisation. Together, these results demonstrate the value of ABM approaches in exploring the interactions on a cell surface, guiding the experimentation for new therapeutic avenues.
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Affiliation(s)
- Chukiat Tantiwong
- School of Biological Sciences, University of Reading, Reading, UK.,Department of Biochemistry, CARIM, Maastricht University, Maastricht, The Netherlands
| | - Joanne L Dunster
- School of Biological Sciences, University of Reading, Reading, UK
| | - Rachel Cavill
- Department of Data Science and Knowledge Engineering, Maastricht University, Maastricht, The Netherlands
| | | | | | - Johan W M Heemskerk
- Department of Biochemistry, CARIM, Maastricht University, Maastricht, The Netherlands.,Synapse Research Institute, Maastricht, The Netherlands
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Han C, Ren P, Mamtimin M, Kruk L, Sarukhanyan E, Li C, Anders HJ, Dandekar T, Krueger I, Elvers M, Goebel S, Adler K, Münch G, Gudermann T, Braun A, Mammadova-Bach E. Minimal Collagen-Binding Epitope of Glycoprotein VI in Human and Mouse Platelets. Biomedicines 2023; 11:biomedicines11020423. [PMID: 36830959 PMCID: PMC9952969 DOI: 10.3390/biomedicines11020423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/22/2023] [Accepted: 01/25/2023] [Indexed: 02/04/2023] Open
Abstract
Glycoprotein VI (GPVI) is a platelet-specific receptor for collagen and fibrin, regulating important platelet functions such as platelet adhesion and thrombus growth. Although the blockade of GPVI function is widely recognized as a potent anti-thrombotic approach, there are limited studies focused on site-specific targeting of GPVI. Using computational modeling and bioinformatics, we analyzed collagen- and CRP-binding surfaces of GPVI monomers and dimers, and compared the interacting surfaces with other mammalian GPVI isoforms. We could predict a minimal collagen-binding epitope of GPVI dimer and designed an EA-20 antibody that recognizes a linear epitope of this surface. Using platelets and whole blood samples donated from wild-type and humanized GPVI transgenic mice and also humans, our experimental results show that the EA-20 antibody inhibits platelet adhesion and aggregation in response to collagen and CRP, but not to fibrin. The EA-20 antibody also prevents thrombus formation in whole blood, on the collagen-coated surface, in arterial flow conditions. We also show that EA-20 does not influence GPVI clustering or receptor shedding. Therefore, we propose that blockade of this minimal collagen-binding epitope of GPVI with the EA-20 antibody could represent a new anti-thrombotic approach by inhibiting specific interactions between GPVI and the collagen matrix.
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Affiliation(s)
- Chao Han
- Walther-Straub-Institute for Pharmacology and Toxicology, Ludwig-Maximilian-University, 80336 Munich, Germany
- Division of Nephrology, Department of Medicine IV, Hospital of the Ludwig-Maximilian-University, 80336 Munich, Germany
| | - Pengxuan Ren
- School of Life Science and Technology, Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China
| | - Medina Mamtimin
- Walther-Straub-Institute for Pharmacology and Toxicology, Ludwig-Maximilian-University, 80336 Munich, Germany
- Division of Nephrology, Department of Medicine IV, Hospital of the Ludwig-Maximilian-University, 80336 Munich, Germany
| | - Linus Kruk
- Walther-Straub-Institute for Pharmacology and Toxicology, Ludwig-Maximilian-University, 80336 Munich, Germany
- Division of Nephrology, Department of Medicine IV, Hospital of the Ludwig-Maximilian-University, 80336 Munich, Germany
| | - Edita Sarukhanyan
- Department of Bioinformatics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Chenyu Li
- Division of Nephrology, Department of Medicine IV, Hospital of the Ludwig-Maximilian-University, 80336 Munich, Germany
| | - Hans-Joachim Anders
- Division of Nephrology, Department of Medicine IV, Hospital of the Ludwig-Maximilian-University, 80336 Munich, Germany
| | - Thomas Dandekar
- Department of Bioinformatics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Irena Krueger
- Department of Vascular and Endovascular Surgery, Heinrich-Heine University Medical Center, 40225 Düsseldorf, Germany
| | - Margitta Elvers
- Department of Vascular and Endovascular Surgery, Heinrich-Heine University Medical Center, 40225 Düsseldorf, Germany
| | | | | | - Götz Münch
- AdvanceCOR GmbH, 82152 Martinsried, Germany
| | - Thomas Gudermann
- Walther-Straub-Institute for Pharmacology and Toxicology, Ludwig-Maximilian-University, 80336 Munich, Germany
- German Center for Lung Research (DZL), 80336 Munich, Germany
| | - Attila Braun
- Walther-Straub-Institute for Pharmacology and Toxicology, Ludwig-Maximilian-University, 80336 Munich, Germany
- Correspondence: (A.B.); (E.M.-B.)
| | - Elmina Mammadova-Bach
- Walther-Straub-Institute for Pharmacology and Toxicology, Ludwig-Maximilian-University, 80336 Munich, Germany
- Division of Nephrology, Department of Medicine IV, Hospital of the Ludwig-Maximilian-University, 80336 Munich, Germany
- Correspondence: (A.B.); (E.M.-B.)
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7
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Modulation of Glycoprotein VI and Its Downstream Signaling Pathways as an Antiplatelet Target. Int J Mol Sci 2022; 23:ijms23179882. [PMID: 36077280 PMCID: PMC9456422 DOI: 10.3390/ijms23179882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 07/06/2022] [Accepted: 07/11/2022] [Indexed: 11/16/2022] Open
Abstract
Antiplatelet therapy aims to reduce the risk of thrombotic events while maintaining hemostasis. A promising current approach is the inhibition of platelet glycoprotein GPVI-mediated adhesion pathways; pathways that do not involve coagulation. GPVI is a signaling receptor integral for collagen-induced platelet activation and participates in the thrombus consolidation process, being a suitable target for thrombosis prevention. Considering this, the blocking or antibody-mediated depletion of GPVI is a promising antiplatelet therapy for the effective and safe treatment of thrombotic diseases without a significant risk of bleeding and impaired hemostatic plug formation. This review describes the current knowledge concerning pharmaceutical approaches to platelet GPVI modulation and its downstream signaling pathways in this context.
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8
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Interaction of von Willebrand factor with blood cells in flow models: a systematic review. Blood Adv 2022; 6:3979-3990. [PMID: 35816358 PMCID: PMC9278308 DOI: 10.1182/bloodadvances.2021006405] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 05/02/2022] [Indexed: 11/29/2022] Open
Abstract
The presence of blood flow influences the interaction between von Willebrand factor (VWF) and blood cells, affecting characteristics of forming blood clots. The interactions between coagulation and inflammation have mainly been studied in thrombosis models, but it remains unclear whether these interactions might also play a role in reduced bleeding in patients with bleeding disorders. In this systematic review, we provide an overview of the literature investigating the interactions between VWF and blood cells in flow models. For article selection, a systematic search was performed in Embase, Medline-Ovid, Cochrane Library, Web of Science databases, and Google Scholar. After selection, 24 articles were included. These articles describe direct or platelet-dependent interactions between VWF and neutrophils, monocytes, erythrocytes, or lymphocytes under different flow conditions. Almost all the described interactions required the presence of activated platelets. Only erythrocytes, monocytes, and natural killer cells were capable of directly binding the VWF multimers. Overall, interactions between VWF and blood cells mainly occurred in the presence of platelets. Because of the large variation in study design and used flow rates, further research is necessary to compare the results between studies and draw firm conclusions on when and under what conditions these interactions can occur. After our findings, many questions remained unanswered. This review might provide a starting point for future research. Extended knowledge on the influence of blood flow on VWF and blood cell interactions can contribute to improved understanding of the variation in bleeding in patients with bleeding disorders.
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9
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GPVI and collagen: the final word? Blood 2022; 139:3005-3007. [PMID: 35587869 DOI: 10.1182/blood.2022015962] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 02/26/2022] [Indexed: 11/20/2022] Open
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10
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Li L, Roest M, Meijers JCM, de Laat B, Urbanus RT, de Groot PG, Huskens D. Platelet Activation via Glycoprotein VI Initiates Thrombin Generation: A Potential Role for Platelet-Derived Factor IX? Thromb Haemost 2022; 122:1502-1512. [PMID: 35512832 DOI: 10.1055/s-0042-1744379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Collagen triggers coagulation via activation of factor (F) XII. In a platelet-rich environment, collagen can also trigger coagulation independently of FXII. We studied a novel mechanism of coagulation initiation via collagen-dependent platelet activation using thrombin generation (TG) in platelet-rich plasma. Collagen-induced coagulation is minimally affected by active-site inactivated FVIIa, anti-FVII antibodies, or FXIIa inhibition (corn trypsin inhibitor). Activation of platelets via specific glycoprotein (GP) VI agonists initiates TG, FX activation, and fibrin formation. To determine the platelet-derived trigger of coagulation, we systematically reconstituted factor-deficient plasmas with washed platelets. TG triggered by GPVI-activated platelets was significantly affected in FIX- and FVIII-deficient plasma but not in FVII- and FXII-deficient plasma. In a purified system composed of FX and FVIII, we observed that absence of FIX was compensated by GPVI-activated platelets, which could be inhibited by an anti-FIX antibody, suggesting FIXa activity from activated platelets. Furthermore, with the addition of FVIII in FIX-deficient plasma, TG induced by GPVI-activated platelets was restored, and was inhibited by the anti-FIX antibody. In conclusion, GPVI-activated platelets initiate TG, probably via platelet-derived FIXa activity.
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Affiliation(s)
- Li Li
- Department of Platelet Pathophysiology, Synapse Research Institute, Maastricht, the Netherlands.,Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Mark Roest
- Department of Platelet Pathophysiology, Synapse Research Institute, Maastricht, the Netherlands.,Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Joost C M Meijers
- Department of Molecular Hematology, Sanquin Research, Amsterdam, The Netherlands.,Department of Experimental Vascular Medicine, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Bas de Laat
- Department of Platelet Pathophysiology, Synapse Research Institute, Maastricht, the Netherlands.,Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Rolf T Urbanus
- Van Creveldkliniek, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Philip G de Groot
- Department of Platelet Pathophysiology, Synapse Research Institute, Maastricht, the Netherlands
| | - Dana Huskens
- Department of Platelet Pathophysiology, Synapse Research Institute, Maastricht, the Netherlands.,Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
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11
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Moroi M, Induruwa I, Farndale RW, Jung SM. Factor XIII is a newly identified binding partner for platelet collagen receptor GPVI-dimer-An interaction that may modulate fibrin crosslinking. Res Pract Thromb Haemost 2022; 6:e12697. [PMID: 35494504 PMCID: PMC9035508 DOI: 10.1002/rth2.12697] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 03/15/2022] [Accepted: 03/18/2022] [Indexed: 11/16/2022] Open
Abstract
Background In the fibrin-forming process, thrombin cleaves fibrinogen to fibrin, which form fibrils and then fibers, producing a gel-like clot. Thrombin also activates coagulation factor XIII (FXIII), which crosslinks fibrin γ-chains and α-chains, stabilizing the clot. Many proteins bind to fibrin, including FXIII, an established regulation of clot structure, and platelet glycoprotein VI (GPVI), whose contribution to clot function is largely unknown. FXIII is present in plasma, but the abundant FXIII in platelet cytosol becomes exposed to the surface of strongly activated platelets. Objectives We determined if GPVI interacts with FXIII and how this might modulate clot formation. Methods We measured interactions between recombinant proteins of the GPVI extracellular domain: GPVI-dimer (GPVI-Fc2) or monomer (GPVIex) and FXIII proteins (nonactivated and thrombin-activated FXIII, FXIII subunits A and B) by ELISA. Binding to fibrin clots and fibrin γ-chain crosslinking were analyzed by immunoblotting. Results GPVI-dimer, but not GPVI-monomer, bound to FXIII. GPVI-dimer selectively bound to the FXIII A-subunit, but not to the B-subunit, an interaction that was decreased or abrogated by the GPVI-dimer-specific antibody mFab-F. The GPVI-dimer-FXIII interaction decreased the extent of γ-chain crosslinking, indicating a role in the regulation of clot formation. Conclusions This is the first report of the specific interaction between GPVI-dimer and the A-subunit of FXIII, as determined in an in vitro system with defined components. GPVI-dimer-FXIII binding was inhibitory toward FXIII-catalyzed crosslinking of fibrin γ-chains in fibrin clots. This raises the possibility that GPVI-dimer may negatively modulate fibrin crosslinking induced by FXIII, lessening clot stability.
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Affiliation(s)
- Masaaki Moroi
- Department of Biochemistry University of Cambridge Cambridge UK
| | - Isuru Induruwa
- Department of Clinical Neurosciences University of Cambridge Cambridge UK
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12
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Olğaç S, Olğaç A, Yenicesu İ, Özkan Y. Identification of Novel Antiplatelet Agents by Targeting Glycoprotein VI: A Combined Virtual Screening Study. Bioorg Chem 2022; 121:105661. [DOI: 10.1016/j.bioorg.2022.105661] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 01/18/2022] [Accepted: 02/05/2022] [Indexed: 11/28/2022]
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13
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Clark JC, Damaskinaki FN, Cheung YFH, Slater A, Watson SP. Structure-function relationship of the platelet glycoprotein VI (GPVI) receptor: does it matter if it is a dimer or monomer? Platelets 2021; 32:724-732. [PMID: 33634725 DOI: 10.1080/09537104.2021.1887469] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/20/2020] [Accepted: 10/26/2020] [Indexed: 10/22/2022]
Abstract
GPVI is a critical signaling receptor responsible for collagen-induced platelet activation and a promising anti-thrombotic target in conditions such as coronary artery thrombosis, ischemic stroke, and atherothrombosis. This is due to the ability to block GPVI while having minimal effects on hemostasis, making it a more attractive target over current dual-antiplatelet therapy (DAPT) with acetyl salicylic acid and P2Y12 inhibitors where bleeding can be a problem. Our current understanding of how the structure of GPVI relates to function is inadequate and recent studies contradict each other. In this article, we summarize the structure-function relationships underlying the activation of GPVI by its major ligands, including collagen, fibrin(ogen), snake venom toxins and charged exogenous ligands such as diesel exhaust particles. We argue that contrary to popular belief dimerization of GPVI is not required for binding to collagen but serves to facilitate binding through increased avidity, and that GPVI is expressed as a mixture of monomers and dimers on resting platelets, with binding of multivalent ligands inducing higher order clustering.
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Affiliation(s)
- Joanne C Clark
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK
| | - Foteini-Nafsika Damaskinaki
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK
- School of Pharmacy, Biodiscovery Institute, University Park, University of Nottingham, Nottingham, UK
| | - Yam Fung Hilaire Cheung
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
- Department of Bioanalytics, Leibniz-Institut Für Analytische Wissenschaften - ISAS -e.v, Dortmund, Germany
| | - Alexandre Slater
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Steve P Watson
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK
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14
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Moroi M, Induruwa I, Farndale RW, Jung SM. Dimers of the platelet collagen receptor glycoprotein VI bind specifically to fibrin fibers during clot formation, but not to intact fibrinogen. J Thromb Haemost 2021; 19:2056-2067. [PMID: 34032355 DOI: 10.1111/jth.15399] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 04/29/2021] [Accepted: 05/19/2021] [Indexed: 12/19/2022]
Abstract
OBJECTIVE The platelet collagen receptor glycoprotein VI (GPVI) has an independent role as a receptor for fibrin produced via the coagulation cascade. However, various reports of GPVI binding to immobilized fibrin(ogen) are not consistent. As a collagen receptor, GPVI-dimer is the functional form, but whether GPVI dimers or monomers bind to fibrin remains controversial. To resolve this, we analyzed GPVI binding to nascent fibrin clots, which more closely approximate physiological conditions. METHODS AND RESULTS ELISA using biotinyl-fibrinogen immobilized on streptavidin-coated wells indicated that GPVI dimers do not bind intact fibrinogen. Clots were formed by adding thrombin to a mixture of near-plasma level of fibrinogen and recombinant GPVI ectodomain: GPVI dimer (GPVI-Fc2 or Revacept) or monomer (GPVI-His: single chain of Revacept GPVI domain, with His tag). Clot-bound proteins were analyzed by SDS-PAGE/immunoblotting. GPVI-dimer bound to noncrosslinked fibrin clots with classical one-site binding kinetics, with µM-level KD , and to crosslinked clots with higher affinity. Anti-GPVI-dimer (mFab-F) inhibited the binding. However, GPVI-His binding to either type of clot was nonsaturable and nearly linear, indicating very low affinity or nonspecific binding. In clots formed in the presence of platelets, clot-bound platelet-derived proteins were integrin αIIbβ3, present at high levels, and GPVI. CONCLUSIONS We conclude that dimeric GPVI is the receptor for fibrin, exhibiting a similar KD to those obtained for its binding to fibrinogen D-fragment and D-dimer, suggesting that fibrin(ogen)'s GPVI-binding site becomes exposed after fibrin formation or cleavage to fragment D. Analysis of platelets bound to fibrin clots indicates that platelet GPVI binds to fibrin fibers comprising the clot.
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Affiliation(s)
- Masaaki Moroi
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Isuru Induruwa
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Richard W Farndale
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Stephanie M Jung
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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15
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Structural characterization of a novel GPVI-nanobody complex reveals a biologically active domain-swapped GPVI dimer. Blood 2021; 137:3443-3453. [PMID: 33512486 DOI: 10.1182/blood.2020009440] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 01/14/2021] [Indexed: 12/22/2022] Open
Abstract
Glycoprotein VI (GPVI) is the major signaling receptor for collagen on platelets. We have raised 54 nanobodies (Nb), grouped into 33 structural classes based on their complementary determining region 3 loops, against recombinant GPVI-Fc (dimeric GPVI) and have characterized their ability to bind recombinant GPVI, resting and activated platelets, and to inhibit platelet activation by collagen. Nbs from 6 different binding classes showed the strongest binding to recombinant GPVI-Fc, suggesting that there was not a single dominant class. The most potent 3, Nb2, 21, and 35, inhibited collagen-induced platelet aggregation with nanomolar half maximal inhibitory concentration (IC50) values and inhibited platelet aggregation under flow. The binding KD of the most potent Nb, Nb2, against recombinant monomeric and dimeric GPVI was 0.6 and 0.7 nM, respectively. The crystal structure of monomeric GPVI in complex with Nb2 revealed a binding epitope adjacent to the collagen-related peptide (CRP) binding groove within the D1 domain. In addition, a novel conformation of GPVI involving a domain swap between the D2 domains was observed. The domain swap is facilitated by the outward extension of the C-C' loop, which forms the domain swap hinge. The functional significance of this conformation was tested by truncating the hinge region so that the domain swap cannot occur. Nb2 was still able to displace collagen and CRP binding to the mutant, but signaling was abolished in a cell-based NFAT reporter assay. This demonstrates that the C-C' loop region is important for GPVI signaling but not ligand binding and suggests the domain-swapped structure may represent an active GPVI conformation.
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16
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Clark JC, Neagoe RAI, Zuidscherwoude M, Kavanagh DM, Slater A, Martin EM, Soave M, Stegner D, Nieswandt B, Poulter NS, Hummert J, Herten DP, Tomlinson MG, Hill SJ, Watson SP. Evidence that GPVI is Expressed as a Mixture of Monomers and Dimers, and that the D2 Domain is not Essential for GPVI Activation. Thromb Haemost 2021; 121:1435-1447. [PMID: 33638140 DOI: 10.1055/a-1401-5014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Collagen has been proposed to bind to a unique epitope in dimeric glycoprotein VI (GPVI) and the number of GPVI dimers has been reported to increase upon platelet activation. However, in contrast, the crystal structure of GPVI in complex with collagen-related peptide (CRP) showed binding distinct from the site of dimerization. Further fibrinogen has been reported to bind to monomeric but not dimeric GPVI. In the present study, we have used the advanced fluorescence microscopy techniques of single-molecule microscopy, fluorescence correlation spectroscopy (FCS) and bioluminescence resonance energy transfer (BRET), and mutagenesis studies in a transfected cell line model to show that GPVI is expressed as a mixture of monomers and dimers and that dimerization through the D2 domain is not critical for activation. As many of these techniques cannot be applied to platelets to resolve this issue, due to the high density of GPVI and its anucleate nature, we used Förster resonance energy transfer (FRET) to show that endogenous GPVI is at least partially expressed as a dimer on resting and activated platelet membranes. We propose that GPVI may be expressed as a monomer on the cell surface and it forms dimers in the membrane through diffusion, giving rise to a mixture of monomers and dimers. We speculate that the formation of dimers facilitates ligand binding through avidity.
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Affiliation(s)
- Joanne C Clark
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom
| | - Raluca A I Neagoe
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Institute of Experimental Biomedicine I, University Hospital and Rudolf Virchow Center, University of Wurzburg, Wurzburg, Germany
| | - Malou Zuidscherwoude
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom
| | - Deirdre M Kavanagh
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom
| | - Alexandre Slater
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Eleyna M Martin
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Mark Soave
- Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom.,Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - David Stegner
- Institute of Experimental Biomedicine I, University Hospital and Rudolf Virchow Center, University of Wurzburg, Wurzburg, Germany
| | - Bernhard Nieswandt
- Institute of Experimental Biomedicine I, University Hospital and Rudolf Virchow Center, University of Wurzburg, Wurzburg, Germany
| | - Natalie S Poulter
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom
| | - Johan Hummert
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom.,Department for Physical Chemistry, Heidelberg University, Heidelberg, Germany
| | - Dirk-Peter Herten
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom.,Department for Physical Chemistry, Heidelberg University, Heidelberg, Germany
| | - Michael G Tomlinson
- Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom.,School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Stephen J Hill
- Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom.,Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Steve P Watson
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom
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17
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Karamanos NK, Theocharis AD, Piperigkou Z, Manou D, Passi A, Skandalis SS, Vynios DH, Orian-Rousseau V, Ricard-Blum S, Schmelzer CEH, Duca L, Durbeej M, Afratis NA, Troeberg L, Franchi M, Masola V, Onisto M. A guide to the composition and functions of the extracellular matrix. FEBS J 2021; 288:6850-6912. [PMID: 33605520 DOI: 10.1111/febs.15776] [Citation(s) in RCA: 304] [Impact Index Per Article: 101.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/13/2021] [Accepted: 02/18/2021] [Indexed: 12/13/2022]
Abstract
Extracellular matrix (ECM) is a dynamic 3-dimensional network of macromolecules that provides structural support for the cells and tissues. Accumulated knowledge clearly demonstrated over the last decade that ECM plays key regulatory roles since it orchestrates cell signaling, functions, properties and morphology. Extracellularly secreted as well as cell-bound factors are among the major members of the ECM family. Proteins/glycoproteins, such as collagens, elastin, laminins and tenascins, proteoglycans and glycosaminoglycans, hyaluronan, and their cell receptors such as CD44 and integrins, responsible for cell adhesion, comprise a well-organized functional network with significant roles in health and disease. On the other hand, enzymes such as matrix metalloproteinases and specific glycosidases including heparanase and hyaluronidases contribute to matrix remodeling and affect human health. Several cell processes and functions, among them cell proliferation and survival, migration, differentiation, autophagy, angiogenesis, and immunity regulation are affected by certain matrix components. Structural alterations have been also well associated with disease progression. This guide on the composition and functions of the ECM gives a broad overview of the matrisome, the major ECM macromolecules, and their interaction networks within the ECM and with the cell surface, summarizes their main structural features and their roles in tissue organization and cell functions, and emphasizes the importance of specific ECM constituents in disease development and progression as well as the advances in molecular targeting of ECM to design new therapeutic strategies.
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Affiliation(s)
- Nikos K Karamanos
- Biochemistry, Biochemical Analysis & Matrix Pathobiology Research Group, Laboratory of Biochemistry, Department of Chemistry, University of Patras, Greece.,Foundation for Research and Technology-Hellas (FORTH)/Institute of Chemical Engineering Sciences (ICE-HT), Patras, Greece
| | - Achilleas D Theocharis
- Biochemistry, Biochemical Analysis & Matrix Pathobiology Research Group, Laboratory of Biochemistry, Department of Chemistry, University of Patras, Greece
| | - Zoi Piperigkou
- Biochemistry, Biochemical Analysis & Matrix Pathobiology Research Group, Laboratory of Biochemistry, Department of Chemistry, University of Patras, Greece.,Foundation for Research and Technology-Hellas (FORTH)/Institute of Chemical Engineering Sciences (ICE-HT), Patras, Greece
| | - Dimitra Manou
- Biochemistry, Biochemical Analysis & Matrix Pathobiology Research Group, Laboratory of Biochemistry, Department of Chemistry, University of Patras, Greece
| | - Alberto Passi
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Spyros S Skandalis
- Biochemistry, Biochemical Analysis & Matrix Pathobiology Research Group, Laboratory of Biochemistry, Department of Chemistry, University of Patras, Greece
| | - Demitrios H Vynios
- Biochemistry, Biochemical Analysis & Matrix Pathobiology Research Group, Laboratory of Biochemistry, Department of Chemistry, University of Patras, Greece
| | - Véronique Orian-Rousseau
- Karlsruhe Institute of Technology, Institute of Biological and Chemical Systems- Functional Molecular Systems, Eggenstein-Leopoldshafen, Germany
| | - Sylvie Ricard-Blum
- University of Lyon, UMR 5246, ICBMS, Université Lyon 1, CNRS, Villeurbanne Cedex, France
| | - Christian E H Schmelzer
- Fraunhofer Institute for Microstructure of Materials and Systems IMWS, Halle (Saale), Germany.,Institute of Pharmacy, Faculty of Natural Sciences I, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Laurent Duca
- UMR CNRS 7369 Matrice Extracellulaire et Dynamique Cellulaire (MEDyC), Team 2: Matrix Aging and Vascular Remodelling, Université de Reims Champagne Ardenne (URCA), UFR Sciences Exactes et Naturelles, Reims, France
| | - Madeleine Durbeej
- Department of Experimental Medical Science, Unit of Muscle Biology, Lund University, Sweden
| | - Nikolaos A Afratis
- Department Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | - Linda Troeberg
- Norwich Medical School, University of East Anglia, Bob Champion Research and Education Building, Norwich, UK
| | - Marco Franchi
- Department for Life Quality Study, University of Bologna, Rimini, Italy
| | | | - Maurizio Onisto
- Department of Biomedical Sciences, University of Padova, Italy
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18
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Xu RG, Gauer JS, Baker SR, Slater A, Martin EM, McPherson HR, Duval C, Manfield IW, Bonna AM, Watson SP, Ariëns RAS. GPVI (Glycoprotein VI) Interaction With Fibrinogen Is Mediated by Avidity and the Fibrinogen αC-Region. Arterioscler Thromb Vasc Biol 2021; 41:1092-1104. [PMID: 33472402 PMCID: PMC7901536 DOI: 10.1161/atvbaha.120.315030] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Supplemental Digital Content is available in the text. Objective: GPVI (glycoprotein VI) is a key molecular player in collagen-induced platelet signaling and aggregation. Recent evidence indicates that it also plays important role in platelet aggregation and thrombus growth through interaction with fibrin(ogen). However, there are discrepancies in the literature regarding whether the monomeric or dimeric form of GPVI binds to fibrinogen at high affinity. The mechanisms of interaction are also not clear, including which region of fibrinogen is responsible for GPVI binding. We aimed to gain further understanding of the mechanisms of interaction at molecular level and to identify the regions on fibrinogen important for GPVI binding. Approach and Results: Using multiple surface- and solution-based protein-protein interaction methods, we observe that dimeric GPVI binds to fibrinogen with much higher affinity and has a slower dissociation rate constant than the monomer due to avidity effects. Moreover, our data show that the highest affinity interaction of GPVI is with the αC-region of fibrinogen. We further show that GPVI interacts with immobilized fibrinogen and fibrin variants at a similar level, including a nonpolymerizing fibrin variant, suggesting that GPVI binding is independent of fibrin polymerization. Conclusions: Based on the above findings, we conclude that the higher affinity of dimeric GPVI over the monomer for fibrinogen interaction is achieved by avidity. The αC-region of fibrinogen appears essential for GPVI binding. We propose that fibrin polymerization into fibers during coagulation will cluster GPVI through its αC-region, leading to downstream signaling, further activation of platelets, and potentially stimulating clot growth.
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Affiliation(s)
- Rui-Gang Xu
- Discovery and Translational Science Department, Institute of Cardiovascular and Metabolic Medicine (R.-G.X., J.S.G., S.R.B., H.R.M., C.D., R.A.S.A.)
| | - Julia S Gauer
- Discovery and Translational Science Department, Institute of Cardiovascular and Metabolic Medicine (R.-G.X., J.S.G., S.R.B., H.R.M., C.D., R.A.S.A.)
| | - Stephen R Baker
- Discovery and Translational Science Department, Institute of Cardiovascular and Metabolic Medicine (R.-G.X., J.S.G., S.R.B., H.R.M., C.D., R.A.S.A.).,Department of Physics, Wake Forest University, Winston Salem, NC (S.R.B.)
| | - Alexandre Slater
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, United Kingdom (A.S., E.M.M., S.P.W.)
| | - Eleyna M Martin
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, United Kingdom (A.S., E.M.M., S.P.W.)
| | - Helen R McPherson
- Discovery and Translational Science Department, Institute of Cardiovascular and Metabolic Medicine (R.-G.X., J.S.G., S.R.B., H.R.M., C.D., R.A.S.A.)
| | - Cédric Duval
- Discovery and Translational Science Department, Institute of Cardiovascular and Metabolic Medicine (R.-G.X., J.S.G., S.R.B., H.R.M., C.D., R.A.S.A.)
| | - Iain W Manfield
- School of Molecular and Cellular Biology, Faculty of Biological Sciences (I.W.M.), University of Leeds, United Kingdom
| | - Arkadiusz M Bonna
- Department of Biochemistry, University of Cambridge, United Kingdom (A.M.B.)
| | - Steve P Watson
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, United Kingdom (A.S., E.M.M., S.P.W.)
| | - Robert A S Ariëns
- Discovery and Translational Science Department, Institute of Cardiovascular and Metabolic Medicine (R.-G.X., J.S.G., S.R.B., H.R.M., C.D., R.A.S.A.)
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19
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Xu ZY, Xu Y, Xie XF, Tian Y, Sui JH, Sun Y, Lin DS, Gao X, Peng C, Fan YJ. Anti-platelet aggregation of Panax notoginseng triol saponins by regulating GP1BA for ischemic stroke therapy. Chin Med 2021; 16:12. [PMID: 33468191 PMCID: PMC7816336 DOI: 10.1186/s13020-021-00424-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 01/08/2021] [Indexed: 12/20/2022] Open
Abstract
Background Panax notoginseng triol saponins (PTS) has been used clinically for ischemic stroke therapy (IST) in China for more than 17 years due to its anti-platelet aggregation and neuro-protective effects, but its mechanism of action is not fully understand. In this study, anti-platelet aggregation-related protein analysis and computer simulations of drug-protein binding interactions were performed to explore the mechanism of the effects of PTS against ischemic stroke in an ischemia reperfusion model. Methods Three oral doses of PTS were administered in a model of middle cerebral artery occlusion (MCAO) in rats. Panax notoginseng total saponins (PNS) and a combination of PTS and aspirin were chosen for comparison. To evaluate therapeutic effects and explore possible mechanisms of anti-platelet aggregation, we measured cerebral infarct size and water content in brain tissue, histomorphological changes, expression of related factors (such as arachidonic acid metabolites) and platelet receptors in serum, as well as the binding affinity of PTS for platelet adhesion receptors. Results Compared with PNS, PTS showed a stronger and more potent anti-platelet aggregation effect in MCAO model rats. The combination of PTS and aspirin could reduce adverse gastrointestinal effects by regulating the TXA2/PGI2 ratio. We demonstrated for the first time that PTS was able to regulate Glycoprotein Ib-α (GP1BA) in a model animal. The binding of ginsenoside Rg1 and GP1BA could form a stable structure. Moreover, PTS could reduce von Willebrand factor (VWF)-mediated platelet adhesion to damaged vascular endothelium, and thus enhance the probability of anti-platelet aggregation and anti-thrombosis under pathological conditions. Conclusions Our results showed that GP1BA was closely related to the anti-platelet aggregation action of PTS, which provided new scientific and molecular evidence for its clinical application.![]()
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Affiliation(s)
- Zhi-Yi Xu
- National Engineering Research Center for Biomaterials, Sichuan University, 29 Wangjiang Road, Chengdu, 610064, Sichuan, China.,Chengdu Huasun Technology Group Inc., Ltd, Shuxin Avenue No.1168, Western Hi-tech Zone, Chengdu, 611731, Sichuan, China
| | - Yang Xu
- National Engineering Research Center for Biomaterials, Sichuan University, 29 Wangjiang Road, Chengdu, 610064, Sichuan, China
| | - Xiao-Fang Xie
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Liutai Avenue NO. 1166, Wenjiang District, Chengdu, 611137, Sichuan, China
| | - Yin Tian
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Liutai Avenue NO. 1166, Wenjiang District, Chengdu, 611137, Sichuan, China
| | - Jun-Hui Sui
- National Engineering Research Center for Biomaterials, Sichuan University, 29 Wangjiang Road, Chengdu, 610064, Sichuan, China
| | - Yong Sun
- National Engineering Research Center for Biomaterials, Sichuan University, 29 Wangjiang Road, Chengdu, 610064, Sichuan, China
| | - Da-Sheng Lin
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Liutai Avenue NO. 1166, Wenjiang District, Chengdu, 611137, Sichuan, China.,Chengdu Huasun Technology Group Inc., Ltd, Shuxin Avenue No.1168, Western Hi-tech Zone, Chengdu, 611731, Sichuan, China
| | - Xing Gao
- Chengdu Huasun Technology Group Inc., Ltd, Shuxin Avenue No.1168, Western Hi-tech Zone, Chengdu, 611731, Sichuan, China
| | - Cheng Peng
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Liutai Avenue NO. 1166, Wenjiang District, Chengdu, 611137, Sichuan, China.
| | - Yu-Jiang Fan
- National Engineering Research Center for Biomaterials, Sichuan University, 29 Wangjiang Road, Chengdu, 610064, Sichuan, China.
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20
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Foster H, Wilson C, Philippou H, Foster R. Progress toward a Glycoprotein VI Modulator for the Treatment of Thrombosis. J Med Chem 2020; 63:12213-12242. [PMID: 32463237 DOI: 10.1021/acs.jmedchem.0c00262] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Pathogenic thrombus formation accounts for the etiology of many serious conditions including myocardial infarction, stroke, deep vein thrombosis, and pulmonary embolism. Despite the development of numerous anticoagulants and antiplatelet agents, the mortality rate associated with these diseases remains high. In recent years, however, significant epidemiological evidence and clinical models have emerged to suggest that modulation of the glycoprotein VI (GPVI) platelet receptor could be harnessed as a novel antiplatelet strategy. As such, many peptidic agents have been described in the past decade, while more recent efforts have focused on the development of small molecule modulators. Herein the rationale for targeting GPVI is summarized and the published GPVI modulators are reviewed, with particular focus on small molecules. A qualitative pharmacophore hypothesis for small molecule ligands at GPVI is also presented.
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Affiliation(s)
- Holly Foster
- School of Chemistry and Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds LS2 9JT, U.K
| | - Clare Wilson
- Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds LS2 9JT, U.K
| | - Helen Philippou
- Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds LS2 9JT, U.K
| | - Richard Foster
- School of Chemistry and Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds LS2 9JT, U.K
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21
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Agarwal G, Smith AW, Jones B. Discoidin domain receptors: Micro insights into macro assemblies. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:118496. [PMID: 31229648 DOI: 10.1016/j.bbamcr.2019.06.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 06/12/2019] [Accepted: 06/13/2019] [Indexed: 12/19/2022]
Abstract
Assembly of cell-surface receptors into specific oligomeric states and/or clusters before and after ligand binding is an important feature governing their biological function. Receptor oligomerization can be mediated by specific domains of the receptor, ligand binding, configurational changes or other interacting molecules. In this review we summarize our understanding of the oligomeric state of discoidin domain receptors (DDR1 and DDR2), which belong to the receptor tyrosine kinase family (RTK). DDRs form an interesting system from an oligomerization perspective as their ligand collagen(s) can also undergo supramolecular assembly to form fibrils. Even though DDR1 and DDR2 differ in the domains responsible to form ligand-free dimers they share similarities in binding to soluble, monomeric collagen. However, only DDR1b forms globular clusters in response to monomeric collagen and not DDR2. Interestingly, both DDR1 and DDR2 are assembled into linear clusters by the collagen fibril. Formation of these clusters is important for receptor phosphorylation and is mediated in part by other membrane components. We summarize how the oligomeric status of DDRs shares similarities with other members of the RTK family and with collagen receptors. Unraveling the multiple macro-molecular configurations adopted by this receptor-ligand pair can provide novel insights into the intricacies of cell-matrix interactions.
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Affiliation(s)
- Gunjan Agarwal
- Biomedical Engineering Department, The Ohio State University, Columbus, OH 43210, USA.
| | - Adam W Smith
- Department of Chemistry, University of Akron, Akron, OH 44325, USA
| | - Blain Jones
- Biomedical Engineering Department, The Ohio State University, Columbus, OH 43210, USA
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GPVI surface expression and signalling pathway activation are increased in platelets from obese patients: Elucidating potential anti-atherothrombotic targets in obesity. Atherosclerosis 2019; 281:62-70. [PMID: 30658193 PMCID: PMC6403451 DOI: 10.1016/j.atherosclerosis.2018.12.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 11/23/2018] [Accepted: 12/21/2018] [Indexed: 02/02/2023]
Abstract
BACKGROUND AND AIMS Platelets play a fundamental role in the increased atherothrombotic risk related to central obesity since they show hyperactivation and lower sensitivity to antiplatelet therapy in obese patients. The main goal of this study was to identify platelet biomarkers related to the risk of atherothrombosis in obese patients, confirm platelet activation levels in these patients, and identify altered activation pathways. METHODS Platelets were obtained from cohorts of obese patients and age- and sex-matched lean controls. Biochemical and proteome analyses were done by two-dimensional differential in-gel electrophoresis (2D-DIGE), mass spectrometry, and immunoblotting. Functional and mechanistic studies were conducted with aggregation assays and flow cytometry. RESULTS We confirmed an up-regulation of αIIb and fibrinogen isoforms in platelets from obese patients. A complementary platelet aggregation approach showed platelets from obese patients are hyper-reactive in response to collagen and collagen-related peptide (CRP), revealing the collagen receptor Glycoprotein VI (GPVI) signalling as one of the altered pathways. We also found the active form of Src (pTyr418) is up-regulated in platelets from obese individuals, which links proteomics to aggregation data. Moreover, we showed that CRP-activated platelets present higher levels of tyrosine phosphorylated PLCγ2 in obese patients, confirming alterations in GPVI signalling. In line with the above, flow cytometry studies show higher surface expression levels of total GPVI and GPVI-dimer in obese platelets, both correlating with BMI. CONCLUSIONS Our results suggest a higher activation state of SFKs-mediated signalling pathways in platelets from obese patients, with a primary involvement of GPVI signalling.
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Roweth HG, Cook AA, Moroi M, Bonna AM, Jung SM, Bergmeier W, Sage SO, Jarvis GE. Two novel, putative mechanisms of action for citalopram-induced platelet inhibition. Sci Rep 2018; 8:16677. [PMID: 30420683 PMCID: PMC6232110 DOI: 10.1038/s41598-018-34389-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 10/12/2018] [Indexed: 02/02/2023] Open
Abstract
Citalopram, a selective serotonin reuptake inhibitor (SSRI), inhibits platelet function in vitro. We have previously shown that this action is independent of citalopram's ability to block serotonin uptake by the serotonin transporter and must therefore be mediated via distinct pharmacological mechanisms. We now report evidence for two novel and putative mechanisms of citalopram-induced platelet inhibition. Firstly, in platelets, citalopram blocked U46619-induced Rap1 activation and subsequent platelet aggregation, but failed to inhibit U46619-induced increases in cytosolic Ca2+. Similarly, in neutrophils, citalopram inhibited Rap1 activation and downstream functions but failed to block PAF-induced Ca2+ mobilisation. In a cell-free system, citalopram also reduced CalDAG-GEFI-mediated nucleotide exchange on Rap1B. Secondly, the binding of anti-GPVI antibodies to resting platelets was inhibited by citalopram. Furthermore, citalopram-induced inhibition of GPVI-mediated platelet aggregation was instantaneous, reversible and displayed competitive characteristics, suggesting that these effects were not caused by a reduction in GPVI surface expression, but by simple competitive binding. In conclusion, we propose two novel, putative and distinct inhibitory mechanisms of action for citalopram: (1) inhibition of CalDAG-GEFI/Rap1 signalling, and (2) competitive antagonism of GPVI in platelets. These findings may aid in the development of novel inhibitors of CalDAG-GEFI/Rap1-dependent nucleotide exchange and novel GPVI antagonists.
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Affiliation(s)
- Harvey G. Roweth
- 0000000121885934grid.5335.0Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Aaron A. Cook
- 0000000122483208grid.10698.36Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, USA
| | - Masaaki Moroi
- 0000000121885934grid.5335.0Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Arkadiusz M. Bonna
- 0000000121885934grid.5335.0Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Stephanie M. Jung
- 0000000121885934grid.5335.0Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Wolfgang Bergmeier
- 0000000122483208grid.10698.36Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, USA
| | - Stewart O. Sage
- 0000000121885934grid.5335.0Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Gavin E. Jarvis
- 0000000121885934grid.5335.0Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
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25
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Slater A, Perrella G, Onselaer MB, Martin EM, Gauer JS, Xu RG, Heemskerk JWM, Ariëns RAS, Watson SP. Does fibrin(ogen) bind to monomeric or dimeric GPVI, or not at all? Platelets 2018; 30:281-289. [DOI: 10.1080/09537104.2018.1508649] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Alexandre Slater
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Gina Perrella
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, Maastricht, The Netherlands
| | - Marie-Blanche Onselaer
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Eleyna M Martin
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Julia S Gauer
- Thrombosis and Tissue Repair Group, Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Rui-Gang Xu
- Thrombosis and Tissue Repair Group, Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Johan WM Heemskerk
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, Maastricht, The Netherlands
| | - Robert A S Ariëns
- Thrombosis and Tissue Repair Group, Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Steve P Watson
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
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26
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Luu S, Gardiner EE, Andrews RK. Bone Marrow Defects and Platelet Function: A Focus on MDS and CLL. Cancers (Basel) 2018; 10:E147. [PMID: 29783667 PMCID: PMC5977120 DOI: 10.3390/cancers10050147] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 05/11/2018] [Accepted: 05/16/2018] [Indexed: 12/16/2022] Open
Abstract
The bloodstream typically contains >500 billion anucleate circulating platelets, derived from megakaryocytes in the bone marrow. This review will focus on two interesting aspects of bone marrow dysfunction and how this impacts on the quality of circulating platelets. In this regard, although megakaryocytes are from the myeloid lineage leading to granulocytes (including neutrophils), erythrocytes, and megakaryocytes/platelets, recent evidence has shown that defects in the lymphoid lineage leading to B cells, T cells, and natural killer (NK) cells also result in abnormal circulating platelets. Current evidence is limited regarding whether this latter phenomenon might potentially arise from (a) some form of as-yet-undetected defect common to both lineages; (b) adverse interactions occurring between cells of different lineages within the bone marrow environment; and/or (c) unknown disease-related factor(s) affecting circulating platelet receptor expression/function after their release from megakaryocytes. Understanding the mechanisms underlying how both myeloid and lymphoid lineage bone marrow defects lead to dysfunction of circulating platelets is significant because of the potential diagnostic and predictive value of peripheral platelet analysis for bone marrow disease progression, the additional potential effects of new anti-cancer drugs on platelet function, and the critical role platelets play in regulation of bleeding risk, inflammation, and innate immunity.
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Affiliation(s)
- Sarah Luu
- Australian Centre for Blood Diseases, Monash University, Melbourne, VIC 3004, Australia.
| | - Elizabeth E Gardiner
- ACRF Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT 2600, Australia.
| | - Robert K Andrews
- Australian Centre for Blood Diseases, Monash University, Melbourne, VIC 3004, Australia.
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Boulaftali Y, Mawhin M, Jandrot‐Perrus M, Ho‐Tin‐Noé B. Glycoprotein VI in securing vascular integrity in inflamed vessels. Res Pract Thromb Haemost 2018; 2:228-239. [PMID: 30046725 PMCID: PMC5974920 DOI: 10.1002/rth2.12092] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 02/08/2018] [Indexed: 12/12/2022] Open
Abstract
Glycoprotein VI (GPVI), the main platelet receptor for collagen, has been shown to play a central role in various models of thrombosis, and to be a minor actor of hemostasis at sites of trauma. These observations have made of GPVI a novel target for antithrombotic therapy, as its inhibition would ideally combine efficacy with safety. Nevertheless, recent studies have indicated that GPVI could play an important role in preventing bleeding caused by neutrophils in the inflamed skin and lungs. Remarkably, there is evidence that the GPVI-dependent hemostatic function of platelets at the acute phase of inflammation in these organs does not involve aggregation. From a therapeutic perspective, the vasculoprotective action of GPVI in inflammation suggests that blocking of GPVI might bear some risks of bleeding at sites of neutrophil infiltration. In this review, we summarize recent findings on GPVI functions in inflammation and discuss their possible clinical implications and applications.
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Affiliation(s)
- Yacine Boulaftali
- Laboratory of Vascular Translational ScienceSorbonne Paris CitéInstitut National de la Santé et de la Recherche Médicale (INSERM)Université Paris DiderotParisFrance
| | - Marie‐Anne Mawhin
- Laboratory of Vascular Translational ScienceSorbonne Paris CitéInstitut National de la Santé et de la Recherche Médicale (INSERM)Université Paris DiderotParisFrance
| | - Martine Jandrot‐Perrus
- Laboratory of Vascular Translational ScienceSorbonne Paris CitéInstitut National de la Santé et de la Recherche Médicale (INSERM)Université Paris DiderotParisFrance
| | - Benoît Ho‐Tin‐Noé
- Laboratory of Vascular Translational ScienceSorbonne Paris CitéInstitut National de la Santé et de la Recherche Médicale (INSERM)Université Paris DiderotParisFrance
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28
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Induruwa I, Moroi M, Bonna A, Malcor J, Howes J, Warburton EA, Farndale RW, Jung SM. Platelet collagen receptor Glycoprotein VI-dimer recognizes fibrinogen and fibrin through their D-domains, contributing to platelet adhesion and activation during thrombus formation. J Thromb Haemost 2018; 16:389-404. [PMID: 29210180 PMCID: PMC5838801 DOI: 10.1111/jth.13919] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Indexed: 01/01/2023]
Abstract
Essentials Glycoprotein VI (GPVI) binds collagen, starting thrombogenesis, and fibrin, stabilizing thrombi. GPVI-dimers, not monomers, recognize immobilized fibrinogen and fibrin through their D-domains. Collagen, D-fragment and D-dimer may share a common or proximate binding site(s) on GPVI-dimer. GPVI-dimer-fibrin interaction supports spreading, activation and adhesion involving αIIbβ3. SUMMARY Background Platelet collagen receptor Glycoprotein VI (GPVI) binds collagen, initiating thrombogenesis, and stabilizes thrombi by binding fibrin. Objectives To determine if GPVI-dimer, GPVI-monomer, or both bind to fibrinogen substrates, and which region common to these substrates contains the interaction site. Methods Recombinant GPVI monomeric extracellular domain (GPVIex ) or dimeric Fc-fusion protein (GPVI-Fc2 ) binding to immobilized fibrinogen derivatives was measured by ELISA, including competition assays involving collagenous substrates and fibrinogen derivatives. Flow adhesion was performed with normal or Glanzmann thrombasthenic (GT) platelets over immobilized fibrinogen, with or without anti-GPVI-dimer or anti-αIIbβ3. Results Under static conditions, GPVIex did not bind to any fibrinogen substrate. GPVI-Fc2 exhibited specific, saturable binding to both D-fragment and D-dimer, which was inhibited by mFab-F (anti-GPVI-dimer), but showed low binding to fibrinogen and fibrin under our conditions. GPVI-Fc2 binding to D-fragment or D-dimer was abrogated by collagen type III, Horm collagen or CRP-XL (crosslinked collagen-related peptide), suggesting proximity between the D-domain and collagen binding sites on GPVI-dimer. Under low shear, adhesion of normal platelets to D-fragment, D-dimer, fibrinogen and fibrin was inhibited by mFab-F (inhibitor of GPVI-dimer) and abolished by Eptifibatide (inhibitor of αIIbβ3), suggesting that both receptors contribute to thrombus formation on these substrates, but αIIbβ3 makes a greater contribution. Notably, thrombasthenic platelets showed limited adhesion to fibrinogen substrates under flow, which was further reduced by mFab-F, supporting some independent GPVI-dimer involvement in this interaction. Conclusion Only dimeric GPVI interacts with fibrinogen D-domain, at a site proximate to its collagen binding site, to support platelet adhesion/activation/aggregate formation on immobilized fibrinogen and polymerized fibrin.
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Affiliation(s)
- I. Induruwa
- Department of Clinical NeurosciencesUniversity of CambridgeCambridgeUK
| | - M. Moroi
- Department of BiochemistryUniversity of CambridgeCambridgeUK
| | - A. Bonna
- Department of BiochemistryUniversity of CambridgeCambridgeUK
| | - J.‐D. Malcor
- Department of BiochemistryUniversity of CambridgeCambridgeUK
| | - J.‐M. Howes
- Department of BiochemistryUniversity of CambridgeCambridgeUK
| | - E. A. Warburton
- Department of Clinical NeurosciencesUniversity of CambridgeCambridgeUK
| | - R. W. Farndale
- Department of BiochemistryUniversity of CambridgeCambridgeUK
| | - S. M. Jung
- Department of BiochemistryUniversity of CambridgeCambridgeUK
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Targeting Intramembrane Protein-Protein Interactions: Novel Therapeutic Strategy of Millions Years Old. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2018; 111:61-99. [PMID: 29459036 PMCID: PMC7102818 DOI: 10.1016/bs.apcsb.2017.06.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Intramembrane protein-protein interactions (PPIs) are involved in transmembrane signal transduction mediated by cell surface receptors and play an important role in health and disease. Recently, receptor-specific modulatory peptides rationally designed using a general platform of transmembrane signaling, the signaling chain homooligomerization (SCHOOL) model, have been proposed to therapeutically target these interactions in a variety of serious diseases with unmet needs including cancer, sepsis, arthritis, retinopathy, and thrombosis. These peptide drug candidates use ligand-independent mechanisms of action (SCHOOL mechanisms) and demonstrate potent efficacy in vitro and in vivo. Recent studies surprisingly revealed that in order to modify and/or escape the host immune response, human viruses use similar mechanisms and modulate cell surface receptors by targeting intramembrane PPIs in a ligand-independent manner. Here, I review these intriguing mechanistic similarities and discuss how the viral strategies optimized over a billion years of the coevolution of viruses and their hosts can help to revolutionize drug discovery science and develop new, disruptive therapies. Examples are given.
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30
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Arthur JF, Gardiner EE, Andrews RK, Al-Tamimi M. Focusing on plasma glycoprotein VI. Thromb Haemost 2017; 107:648-55. [DOI: 10.1160/th11-10-0745] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 12/10/2011] [Indexed: 12/18/2022]
Abstract
SummaryNew methods for analysing both platelet and plasma forms of the platelet-specific collagen receptor, glycoprotein VI (GPVI) in experimental models or human clinical samples, and the development of the first therapeutic compounds based on dimeric soluble GPVI-Fc or anti-GPVI antibody-based constructs, coincide with increased understanding of the potential pathophysiological role of GPVI ligand binding and shedding. Platelet GPVI not only mediates platelet activation at the site of vascular injury where collagen is exposed, but is also implicated in the pathogenesis of other diseases, such as atherosclerosis and coagulopathy, rheumatoid arthritis and tumour metastasis. Here, we describe some of the critical mechanisms for generating soluble GPVI from platelets, and future avenues for exploiting this unique platelet-specific receptor for diagnosis and/or disease prevention.
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31
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Mojica Muñoz AK, Jamasbi J, Uhland K, Degen H, Münch G, Ungerer M, Brandl R, Megens R, Weber C, Lorenz R, Siess W. Recombinant GPVI-Fc added to single or dual antiplatelet therapy in vitro prevents plaque-induced platelet thrombus formation. Thromb Haemost 2017; 117:1651-1659. [DOI: 10.1160/th16-11-0856] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 05/04/2017] [Indexed: 11/05/2022]
Abstract
SummaryThe efficiency of current dual antiplatelet therapy might be further improved by its combination with a glycoprotein (GP) VI-targeting strategy without increasing bleeding. GPVI-Fc, a recombinant dimeric fusion protein binding to plaque collagen and concealing binding sites for platelet GPVI, acts as a lesion-focused antiplatelet drug, and does not increase bleeding in vivo. We investigated, whether GPVI-Fc added in vitro on top of acetylsalicylic acid (ASA), the P2Y12 antagonist ticagrelor, and the fibrinogen receptor antagonist abciximab alone or in combination would increase inhibition of platelet activation by atherosclerotic plaque. Under static conditions, GPVI-Fc inhibited plaque-induced platelet aggregation by 53%, and increased platelet inhibition by ASA (51%) and ticagrelor (64%) to 66% and 80%, respectively. Under arterial flow, GPVI-Fc inhibited plaque-induced platelet aggregation by 57%, and significantly increased platelet inhibition by ASA (28%) and ticagrelor (47%) to about 81% each. The triple combination of GPVI-Fc, ASA and ticagrelor achieved almost complete inhibition of plaque-induced platelet aggregation (93%). GPVI-Fc alone or in combination with ASA or ticagrelor did not increase closure time measured by the platelet function analyzer (PFA)-200. GPVI-Fc added on top of abciximab, a clinically used anti-fibrinogen receptor antibody which blocks platelet aggregation, strongly inhibited total (81%) and stable (89%) platelet adhesion. We conclude that GPVI-Fc added on top of single or dual antiplatelet therapy with ASA and/or a P2Y12 antagonist is likely to improve anti-atherothrombotic protection without increasing bleeding risk. In contrast, the strong inhibition of platelet adhesion by GPVI-Fc in combination with GPIIb/IIIa inhibitors could be harmful.Note: The review process for this manuscript was fully handled by Gregory Y. H. Lip, Editor in Chief.Supplementary Material to this article is available at www.thrombosis-online.com.
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32
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Wufuer Y, Shan X, Sailike M, Adilaimu K, Ma S, Wang H. GPVI‑Fc‑PEG improves cerebral infarct volume and cerebral thrombosis in mouse model with cerebral thrombosis. Mol Med Rep 2017; 16:7561-7568. [PMID: 28944903 DOI: 10.3892/mmr.2017.7556] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 02/07/2017] [Indexed: 11/05/2022] Open
Abstract
Cerebral thrombosis is one of the most common causes of cerebral infarction, and anticoagulation therapy is a routine treatment in patients with hemorrhagic cerebral venous thrombosis. The hemostatic function of platelets is important for the anticoagulation therapy of thrombosis. Glycoprotein VI (GPVI) is reported as the major signaling receptor for collagen and is exclusively expressed on platelets and megakaryocytes, initiating platelet recruitment at sites of vascular injury and demonstrating numerous beneficial effects for patients with cerebral thrombosis. In the present study, thrombus formation and platelet adhesion following endothelial injury was monitored in the jugular vein by intra‑vital fluorescence microscopy. The morphological and clinical observations of cerebral thrombosis were investigated and analyzed in a mouse model with cerebral thrombosis. In addition, the present study investigated the effect of fusion protein GPVI modified with Fc and PEG, which is specifically linked to the extracellular domain of GPVI (GPVI‑Fc‑PEG), on thrombus formation following vessel wall injury and on experimental mice with cerebral thrombosis. The maximum tolerated dose (MTD) was identified as 0.18 mg. GPVI‑Fc‑PEG competitively bound to and prevented von Willebrand Factor‑collagen interactions. The results of the present study demonstrated that cerebral thrombosis was greatly relieved and improved functional outcomes treatment with an MTD of GPVI‑Fc‑PEG following endothelial injury, compared with GPVI‑Fc‑treated mice. In addition, cerebral edema and infarct size was improved compared with GPVI‑Fc‑treated mice with ischemic stroke immediately prior to reperfusion. Furthermore, treatment of GPVI‑Fc‑PEG led to increased reperfusion and improved survival following cerebral thrombosis compared with treatment with either single agent alone. Taken together, GPVI‑Fc‑PEG relieved cerebral thrombosis following ischemic stroke and improved prognostic preclinical outcomes without intracranial bleeding, which suggested that GPVI‑Fc‑PEG may be a potential candidate for cerebral thrombosis therapy.
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Affiliation(s)
- Yimae Wufuer
- Department of Vascular Thyroid Surgery, Gastrointestinal Vascular Center, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang 830054, P.R. China
| | - Xuefeng Shan
- The First Department of Pediatric Surgery, Gastrointestinal Vascular Center, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang 830054, P.R. China
| | - Magaoweiya Sailike
- Department of Vascular Thyroid Surgery, Gastrointestinal Vascular Center, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang 830054, P.R. China
| | - Kamile Adilaimu
- Department of Vascular Thyroid Surgery, Gastrointestinal Vascular Center, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang 830054, P.R. China
| | - Songfeng Ma
- The First Department of Pediatric Surgery, Gastrointestinal Vascular Center, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang 830054, P.R. China
| | - Huguo Wang
- Department of Vascular Thyroid Surgery, Gastrointestinal Vascular Center, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang 830054, P.R. China
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Poulter NS, Pollitt AY, Owen DM, Gardiner EE, Andrews RK, Shimizu H, Ishikawa D, Bihan D, Farndale RW, Moroi M, Watson SP, Jung SM. Clustering of glycoprotein VI (GPVI) dimers upon adhesion to collagen as a mechanism to regulate GPVI signaling in platelets. J Thromb Haemost 2017; 15:549-564. [PMID: 28058806 PMCID: PMC5347898 DOI: 10.1111/jth.13613] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Indexed: 01/01/2023]
Abstract
Essentials Dimeric high-affinity collagen receptor glycoprotein VI (GPVI) is present on resting platelets. Spatio-temporal organization of platelet GPVI-dimers was evaluated using advanced microscopy. Upon platelet adhesion to collagenous substrates, GPVI-dimers coalesce to form clusters. Clustering of GPVI-dimers may increase avidity and facilitate platelet activation SUMMARY: Background Platelet glycoprotein VI (GPVI) binding to subendothelial collagen exposed upon blood vessel injury initiates thrombus formation. Dimeric GPVI has high affinity for collagen, and occurs constitutively on resting platelets. Objective To identify higher-order oligomerization (clustering) of pre-existing GPVI dimers upon interaction with collagen as a mechanism to initiate GPVI-mediated signaling. Methods GPVI was located by use of fluorophore-conjugated GPVI dimer-specific Fab (antigen-binding fragment). The tested substrates include Horm collagen I fibers, soluble collagen III, GPVI-specific collagen peptides, and fibrinogen. GPVI dimer clusters on the platelet surface interacting with these substrates were visualized with complementary imaging techniques: total internal reflection fluorescence microscopy to monitor real-time interactions, and direct stochastic optical reconstruction microscopy (dSTORM), providing relative quantification of GPVI cluster size and density. Confocal microscopy was used to locate GPVI dimer clusters, glycoprotein Ib, integrin α2 β1 , and phosphotyrosine. Results Upon platelet adhesion to all collagenous substrates, GPVI dimers coalesced to form clusters; notably clusters formed along the fibers of Horm collagen. dSTORM revealed that GPVI density within clusters depended on the substrate, collagen III being the most effective. Clusters on fibrinogen-adhered platelets were much smaller and more numerous; whether these are pre-existing oligomers of GPVI dimers or fibrinogen-induced is not clear. Some GPVI dimer clusters colocalized with areas of phosphotyrosine, indicative of signaling activity. Integrin α2 β1 was localized to collagen fibers close to GPVI dimer clusters. GPVI clustering depends on a dynamic actin cytoskeleton. Conclusions Platelet adhesion to collagen induces GPVI dimer clustering. GPVI clustering increases both avidity for collagen and the proximity of GPVI-associated signaling molecules, which may be crucial for the initiation and persistence of signaling.
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Affiliation(s)
- N. S. Poulter
- Institute of Cardiovascular SciencesCollege of Medical and Dental SciencesUniversity of BirminghamBirminghamUK
- Centre for Membrane Proteins and Receptors (COMPARE)College of Medical and Dental SciencesUniversity of BirminghamBirminghamUK
| | - A. Y. Pollitt
- Institute of Cardiovascular SciencesCollege of Medical and Dental SciencesUniversity of BirminghamBirminghamUK
- Present address: Institute for Cardiovascular and Metabolic ResearchSchool of Biological SciencesUniversity of ReadingReadingRG6 6ASUK
| | - D. M. Owen
- Department of Physics and Randall Division of Cell and Molecular BiophysicsKing's College LondonLondonUK
| | - E. E. Gardiner
- Department of Cancer Biology and TherapeuticsJohn Curtin School of Medical ResearchAustralian National UniversityCanberraACTAustralia
| | - R. K. Andrews
- Australian Centre for Blood DiseasesMonash UniversityMelbourneVictoriaAustralia
| | - H. Shimizu
- Research DepartmentChemo‐Sero‐Therapeutic Research InstituteKaketsukenKumamotoJapan
| | - D. Ishikawa
- Research DepartmentChemo‐Sero‐Therapeutic Research InstituteKaketsukenKumamotoJapan
| | - D. Bihan
- Department of BiochemistryUniversity of CambridgeCambridgeUK
| | - R. W. Farndale
- Department of BiochemistryUniversity of CambridgeCambridgeUK
| | - M. Moroi
- Department of BiochemistryUniversity of CambridgeCambridgeUK
| | - S. P. Watson
- Institute of Cardiovascular SciencesCollege of Medical and Dental SciencesUniversity of BirminghamBirminghamUK
- Centre for Membrane Proteins and Receptors (COMPARE)College of Medical and Dental SciencesUniversity of BirminghamBirminghamUK
| | - S. M. Jung
- Department of BiochemistryUniversity of CambridgeCambridgeUK
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34
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Induruwa I, Jung SM, Warburton EA. Beyond antiplatelets: The role of glycoprotein VI in ischemic stroke. Int J Stroke 2016; 11:618-25. [PMID: 27312676 PMCID: PMC5390959 DOI: 10.1177/1747493016654532] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 05/03/2016] [Indexed: 11/17/2022]
Abstract
Background Platelets are essential to physiological hemostasis or pathological thrombus formation. Current antiplatelet agents inhibit platelet aggregation but leave patients at risk of systemic side-effects such as hemorrhage. Newer therapeutic strategies could involve targeting this cascade earlier during platelet adhesion or activation via inhibitory effects on specific glycoproteins, the thrombogenic collagen receptors found on the platelet surface. Aims Glycoprotein VI (GPVI) is increasingly being recognized as the main platelet-collagen receptor involved in arterial thrombosis. This review summarizes the crucial role GPVI plays in ischemic stroke as well as the current strategies used to attempt to inhibit its activity. Summary of review In this review, we discuss the normal hemostatic process, and the role GPVI plays at sites of atherosclerotic plaque rupture. We discuss how the unique structure of GPVI allows for its interaction with collagen and creates downstream signaling that leads to thrombus formation. We summarize the current strategies used to inhibit GPVI activity and how this could translate to a clinically viable entity that may compete with current antiplatelet therapy. Conclusion From animal models, it is clear that GPVI inhibition leads to an abolished platelet response to collagen and reduced platelet aggregation, culminating in smaller arterial thrombi. There is now an increasing body of evidence that these findings can be translated into the development of a bleeding free pharmacological entity specific to sites of plaque rupture in humans.
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Affiliation(s)
- Isuru Induruwa
- Department of Clinical Neurosciences, Box 83, Cambridge University Biomedical Campus, Cambridge, UK
| | - Stephanie M Jung
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Elizabeth A Warburton
- Department of Clinical Neurosciences, Box 83, Cambridge University Biomedical Campus, Cambridge, UK
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Howes JM, Pugh N, Knäuper V, Farndale RW. Modified platelet deposition on matrix metalloproteinase 13 digested collagen I. J Thromb Haemost 2015; 13:2253-9. [PMID: 26447617 PMCID: PMC4855633 DOI: 10.1111/jth.13166] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 09/23/2015] [Indexed: 11/28/2022]
Abstract
BACKGROUND Atherothrombosis underlies acute coronary syndromes, including unstable angina and acute myocardial infarction. Within the unstable plaque, monocytes express collagenolytic matrix metalloproteinases (MMPs), including MMP-13, which degrades fibrous collagen. Following rupture, vessel wall components including degraded collagen are exposed to circulating platelets. Platelet receptors then mediate the recruitment and activation of platelets to form a thrombus, blocking blood flow and resulting in myocardial infarction and sudden death. OBJECTIVES Here we aim to provide information on the effects of collagen degradation on platelet adhesion and thrombus formation. METHODS Using increasing concentrations of MMP-13, we induced progressive degradation of fibrous and monomeric collagen I, visualized by electrophoresis, and then investigated the capacity of the resulting fragments to support static platelet adhesion and thrombus formation in whole flowing blood. RESULTS Both integrin and glycoprotein VI-dependent interactions with fibrous collagen underpin high levels of platelet adhesion under both conditions, with little obvious effect of MMP-13 treatment. Static platelet adhesion to monomeric collagen was strongly α2β1-dependent regardless of degradation status. Under flow conditions, partially degraded monomeric collagen supported increased thrombus deposition at 10 μg mL(-1) MMP-13, falling close to background when collagen degradation was complete (100 μg mL(-1) MMP-13). CONCLUSIONS New binding activities come into play after partial digestion of collagen monomers, and net platelet-reactivity through all axes is abolished as degradation becomes more complete.
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Affiliation(s)
- J-M Howes
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - N Pugh
- Department of Biomedical and Forensic Science, Anglia Ruskin University, Cambridge, UK
| | - V Knäuper
- Cardiff University Dental School, Cardiff, UK
| | - R W Farndale
- Department of Biochemistry, University of Cambridge, Cambridge, UK
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Jamasbi J, Megens RTA, Bianchini M, Münch G, Ungerer M, Faussner A, Sherman S, Walker A, Goyal P, Jung S, Brandl R, Weber C, Lorenz R, Farndale R, Elia N, Siess W. Differential Inhibition of Human Atherosclerotic Plaque-Induced Platelet Activation by Dimeric GPVI-Fc and Anti-GPVI Antibodies: Functional and Imaging Studies. J Am Coll Cardiol 2015; 65:2404-15. [PMID: 26046734 PMCID: PMC4452546 DOI: 10.1016/j.jacc.2015.03.573] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 03/25/2015] [Accepted: 03/31/2015] [Indexed: 12/20/2022]
Abstract
Background Glycoprotein VI (GPVI) is the essential platelet collagen receptor in atherothrombosis, but its inhibition causes only a mild bleeding tendency. Thus, targeting this receptor has selective antithrombotic potential. Objectives This study sought to compare compounds interfering with platelet GPVI–atherosclerotic plaque interaction to improve current antiatherothrombotic therapy. Methods Human atherosclerotic plaque–induced platelet aggregation was measured in anticoagulated blood under static and arterial flow conditions (550/s, 1,100/s, and 1,500/s). Inhibition by dimeric GPVI fragment crystallizable region of IgG (Fc) masking GPVI binding sites on collagen was compared with that of 3 anti-GPVI antibodies: BLO8-1, a human domain antibody; 5C4, a fragment antigen-binding (Fab fragment) of monoclonal rat immunoglobulin G; and m-Fab-F, a human recombinant sFab against GPVI dimers. Results GPVI-Fc reduced plaque-triggered platelet aggregation in static blood by 51%, BLO8-1 by 88%, and 5C4 by 93%. Under arterial flow conditions, BLO8-1 and 5C4 almost completely inhibited platelet aggregation while preserving platelet adhesion on plaque. Inhibition by GPVI-Fc, even at high concentrations, was less marked but increased with shear rate. Advanced optical imaging revealed rapid persistent GPVI-Fc binding to collagen under low and high shear flow, upstream and downstream of plaque fragments. At low shear particularly, platelets adhered in plaque flow niches to GPVI-Fc–free segments of collagen fibers and recruited other platelets onto aggregates via ADP and TxA2 release. Conclusions Anti-GPVI antibodies inhibit atherosclerotic plaque-induced platelet aggregation under static and flow conditions more effectively than GPVI-Fc. However, potent platelet inhibition by GPVI-Fc at a higher shear rate (1,500/s) suggests localized antithrombotic efficacy at denuded or fissured stenotic high-risk lesions without systemic bleeding. The compound-specific differences have relevance for clinical trials targeting GPVI-collagen interaction combined with established antiplatelet therapies in patients with spontaneous plaque rupture or intervention-associated plaque injury.
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Affiliation(s)
- Janina Jamasbi
- Institute for the Prevention of Cardiovascular Diseases, University of Munich, Munich, Germany
| | - Remco T A Megens
- Institute for the Prevention of Cardiovascular Diseases, University of Munich, Munich, Germany; Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands
| | - Mariaelvy Bianchini
- Institute for the Prevention of Cardiovascular Diseases, University of Munich, Munich, Germany
| | | | | | - Alexander Faussner
- Institute for the Prevention of Cardiovascular Diseases, University of Munich, Munich, Germany
| | - Shachar Sherman
- Department of Life Sciences, Ben Gurion University, Beer-Sheva, Israel
| | - Adam Walker
- GlaxoSmithKline Research & Development, Brentford, Middlesex, United Kingdom
| | - Pankaj Goyal
- Department of Biotechnology, The Central University of Rajasthan, Rajasthan, India
| | - Stephanie Jung
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Richard Brandl
- St. Mary's Square Institute for Vascular Surgery and Phlebology, Munich, Germany
| | - Christian Weber
- Institute for the Prevention of Cardiovascular Diseases, University of Munich, Munich, Germany; Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands; DZHK (German Centre for Cardiovascular Research), partner site Munich Heart Alliance, Munich, Germany
| | - Reinhard Lorenz
- Institute for the Prevention of Cardiovascular Diseases, University of Munich, Munich, Germany
| | - Richard Farndale
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Natalie Elia
- Department of Life Sciences, Ben Gurion University, Beer-Sheva, Israel
| | - Wolfgang Siess
- Institute for the Prevention of Cardiovascular Diseases, University of Munich, Munich, Germany; DZHK (German Centre for Cardiovascular Research), partner site Munich Heart Alliance, Munich, Germany.
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Establishment of immunoassay for platelet-derived soluble glycoprotein VI, a novel platelet marker. J Immunol Methods 2015; 418:52-60. [PMID: 25655782 DOI: 10.1016/j.jim.2015.01.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 12/31/2014] [Accepted: 01/26/2015] [Indexed: 11/24/2022]
Abstract
Soluble Glycoprotein VI (GPVI) is an attractive marker for disorders marked by platelet activation, such as thrombotic microangiopathy, myocardial infarction, and stroke. Several groups have already developed an immunoassay for soluble GPVI; however, there are several discrepancies between the groups' assays. In this study, we prepared the two types of recombinant soluble GPVI, the monomeric form GPVI (GPVI-His) and the dimeric form of GPVI (GPVI-Fc), moreover, we generated four anti-GPVI antibodies, F1232-7-1 (7S1), F1232-10-2 (10S2), F1232-19-1 (19D1), and F1232-21-1 (21D1). The former 2 antibodies (7S1 and 10S2) had a high affinity for both GPVI-His and GPVI-Fc, while the latter 2 antibodies (19D1 and 21D1) showed a high affinity for GPVI-Fc but low affinity for GPVI-His. All of the antibodies comparably recognized surface GPVI on resting platelets. Furthermore, we established two immunoassays for soluble GPVI, 7S1/10S2-HRP and 19D1/21D1-HRP (capture antibody/detection antibody). 7S1/10S2-HRP showed equivalent reactivity with GPVI-His and GPVI-Fc, whereas 19D1/21D1-HRP had high affinity for GPVI-Fc but low reactivity with GPVI-His. In terms of reactivity with platelet-derived soluble GPVI, 7S1/10S2-HRP demonstrated sensitive detection whereas 19D1/21D1-HRP was nonreactive. Taken together, 7S1/10S2-HRP is a suitable candidate for a reliable soluble GPVI immunoassay as it has a high affinity for monomeric GPVI.
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Ozaki Y, Suzuki-Inoue K, Inoue O. Platelet receptors activated via mulitmerization: glycoprotein VI, GPIb-IX-V, and CLEC-2. J Thromb Haemost 2013; 11 Suppl 1:330-9. [PMID: 23809136 DOI: 10.1111/jth.12235] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
While very different in structure, GPVI - the major collagen receptor on platelet membranes, the GPIb-IX-V complex - the receptor for von Willebrand factor, and CLEC-2, a novel platelet activation receptor for podoplanin, share several common features in terms of function and platelet activation signal transduction pathways. All employ Src family kinases (SFK), Syk, and other signaling molecules involving tyrosine phosphorylation, similar to those of immunoreceptors for T and B cells. There appear to be overlapping functional roles for these glycoproteins, and in some cases, they can compensate for each other, suggesting a degree of redundancy. New ligands for these receptors are being identified, which broadens their functional relevancy. This is particularly true for CLEC-2, whose functions beyond hemostasis are being explored. The common mode of signaling, clustering, and localization to glycosphingolipid-enriched microdomains (GEMs) suggest that GEMs are central to signaling function by ligand-dependent association of these receptors, SFK, Syk, phosphotyrosine phosphatases, and other signaling molecules.
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Affiliation(s)
- Y Ozaki
- Department of Laboratory Medicine, Faculty of Medicine, University of Yamanashi, Chuo, Yamanashi, Japan.
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Zahid M, Mangin P, Loyau S, Hechler B, Billiald P, Gachet C, Jandrot-Perrus M. The future of glycoprotein VI as an antithrombotic target. J Thromb Haemost 2012; 10:2418-27. [PMID: 23020554 DOI: 10.1111/jth.12009] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The treatment of acute coronary syndromes has been considerably improved in recent years with the introduction of highly efficient antiplatelet drugs. However, there are still significant limitations: the recurrence of adverse vascular events remains a problem, and the improvement in efficacy is counterbalanced by an increased risk of bleeding, which is of particular importance in patients at risk of stroke. One of the most attractive targets for the development of new molecules with potential antithrombotic activity is platelet glycoprotein (GP)VI, because its blockade appears to ideally combine efficacy and safety. This review summarizes current knowledge on GPVI regarding its structure, its function, and its role in physiologic hemostasis and thrombosis. Strategies for inhibiting GPVI are presented, and evidence of the antithrombotic efficacy and safety of GPVI antagonists is provided.
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Affiliation(s)
- M Zahid
- Inserm, UMRS_698, Paris, France
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40
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Jung SM, Moroi M, Soejima K, Nakagaki T, Miura Y, Berndt MC, Gardiner EE, Howes JM, Pugh N, Bihan D, Watson SP, Farndale RW. Constitutive dimerization of glycoprotein VI (GPVI) in resting platelets is essential for binding to collagen and activation in flowing blood. J Biol Chem 2012; 287:30000-13. [PMID: 22773837 PMCID: PMC3436176 DOI: 10.1074/jbc.m112.359125] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 06/15/2012] [Indexed: 11/06/2022] Open
Abstract
The platelet collagen receptor glycoprotein VI (GPVI) has been suggested to function as a dimer, with increased affinity for collagen. Dissociation constants (K(d)) obtained by measuring recombinant GPVI binding to collagenous substrates showed that GPVI dimers bind with high affinity to tandem GPO (Gly-Pro-Hyp) sequences in collagen, whereas the markedly lower affinity of the monomer for all substrates implies that it is not the collagen-binding form of GPVI. Dimer binding required a high density of immobilized triple-helical (GPO)(10)-containing peptide, suggesting that the dimer binds multiple, discrete peptide helices. Differential inhibition of dimer binding by dimer-specific antibodies, m-Fab-F and 204-11 Fab, suggests that m-Fab-F binds at the collagen-binding site of the dimer, and 204-11 Fab binds to a discrete site. Flow cytometric quantitation indicated that GPVI dimers account for ~29% of total GPVI in resting platelets, whereas activation by either collagen-related peptide or thrombin increases the number of dimers to ~39 and ~44%, respectively. m-Fab-F inhibits both GPVI-dependent static platelet adhesion to collagen and thrombus formation on collagen under low and high shear, indicating that pre-existing dimeric GPVI is required for the initial interaction with collagen because affinity of the monomer is too low to support binding and that interaction through the dimer is essential for platelet activation. These GPVI dimers in resting circulating platelets will enable them to bind injury-exposed subendothelial collagen to initiate platelet activation. The GPVI-specific agonist collagen-related peptide or thrombin further increases the number of dimers, thereby providing a feedback mechanism for reinforcing binding to collagen and platelet activation.
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Affiliation(s)
- Stephanie M Jung
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK.
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Sigalov AB. "Monovalent" ligands that trigger TLR-4 and TCR are not necessarily truly monovalent. Mol Immunol 2012; 51:356-62. [PMID: 22520974 DOI: 10.1016/j.molimm.2012.03.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 03/25/2012] [Indexed: 01/23/2023]
Abstract
Cell surface receptors mediate many cellular responses in health and disease. Recent progress in our understanding of how ligand binding to the extracellular domains of receptors triggers intracellular signaling has underlined the role of ligand-promoted receptor clustering following by oligomerization of the cytoplasmic signaling domains. The clustering suggests the requirement of ligand multivalency and is especially important for triggering receptors involved in innate and adaptive immune responses. However, although numerous studies have established that multivalent, but not monovalent, ligands induce receptor-mediated signal transduction, considerable uncertainty still remains. Here, I hypothesize that "monovalent" ligands that have been reported to trigger immune receptors in vitro are not necessarily truly monovalent. This is illustrated by focusing on studies of signal transduction by toll-like receptor-4 and T cell receptor. By generalizing this concept to a variety of lipid and protein ligands, one would propose an alternative interpretation of apparent ligand monovalency in other receptor activation studies as well.
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Deckmyn H, De Meyer SF, Broos K, Vanhoorelbeke K. Inhibitors of the interactions between collagen and its receptors on platelets. Handb Exp Pharmacol 2012:311-337. [PMID: 22918737 DOI: 10.1007/978-3-642-29423-5_13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
At sites of vascular injury, collagen-mediated platelet adhesion and activation have long been known as one of the first events in platelet-dependent thrombus formation. Studying patients with bleeding disorders that are caused by defective platelet adhesion to collagen resulted in the identification of several platelet collagen receptors, with glycoprotein VI and integrin α2β1 being the most important ones. Subsequent development of specific collagen receptor knockout mice and various inhibitors of platelet binding to collagen have further proven the role of these receptors in haemostasis and thrombosis. The search for clinically applicable inhibitors for use as antithrombotic drug has led to the identification of inhibitory antibodies, soluble receptor fragments, peptides, collagen-mimetics and proteins from snake venoms or haematophagous animals. In experimental settings, these inhibitors have a good antithrombotic effect, with little prolongation of bleeding times, suggesting a larger therapeutic window than currently available antiplatelet drugs. However, at present, none of the collagen receptor blockers are in clinical development yet.
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Affiliation(s)
- Hans Deckmyn
- Laboratory for Thrombosis Research, KU Leuven campus Kortrijk, Kortrijk, Belgium.
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Loyau S, Dumont B, Ollivier V, Boulaftali Y, Feldman L, Ajzenberg N, Jandrot-Perrus M. Platelet glycoprotein VI dimerization, an active process inducing receptor competence, is an indicator of platelet reactivity. Arterioscler Thromb Vasc Biol 2011; 32:778-85. [PMID: 22155453 DOI: 10.1161/atvbaha.111.241067] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
OBJECTIVE The immune receptor homologue glycoprotein VI (GPVI)/FcR receptor γ chain complex is primarily responsible for platelet activation by collagen. There is growing evidence that optimal binding of GPVI to collagen depends on the assembly of GPVI dimers. The valence of GPVI on resting platelets needs to be clearly established because platelet avidity for collagen would be greater if GPVI is constitutively expressed as a dimer than as a monomer. METHODS AND RESULTS Using a monoclonal antibody (9E18) that preferentially binds to GPVI dimers, we found that GPVI was maintained in a monomeric form on human resting platelets under the control of intraplatelet cAMP concentration. Activation by soluble agonists or von Willebrand factor induced a shift toward GPVI dimerization related to increased platelet adhesion to collagen. A correlation between platelet binding of 9E18 and P-selectin exposure was observed in patients experiencing coronary artery disease, and antagonists of the ADP receptor P2Y12 limited ADP-induced GPVI dimerization. CONCLUSION The rapid assembly of highly competent dimers of GPVI at sites of vascular lesion represents an important step in the sequence of events leading to platelet activation by collagen. GPVI dimers could represent a new marker to analyze platelet reactivity.
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Affiliation(s)
- Stéphane Loyau
- INSERM U698, CHU Xavier Bichat, 46 rue Henri Huchard 75877 Paris Cedex 18, France
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Abstract
Collagen, the most abundant protein in animals, is a key component of extracellular matrices. Not only do collagens provide essential structural support for connective tissues, but they are also intimately involved in controlling a spectrum of cellular functions such as growth, differentiation, and morphogenesis. All collagens possess triple-helical regions through which they interact with a host of other proteins including cell surface receptors. A structurally diverse group of transmembrane receptors mediates the recognition of the collagen triple helix: integrins, discoidin domain receptors, glycoprotein VI, and leukocyte-associated immunoglobulin-like receptor-1. These collagen receptors regulate a wide range of behaviors including cell adhesion and migration, hemostasis, and immune function. Here these collagen receptors are discussed in terms of their molecular basis of collagen recognition, their signaling and developmental functions, and their roles in disease.
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Affiliation(s)
- Birgit Leitinger
- National Heart and Lung Institute, Imperial College London, London SW7 2AZ, United Kingdom.
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45
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Broos K, Feys HB, De Meyer SF, Vanhoorelbeke K, Deckmyn H. Platelets at work in primary hemostasis. Blood Rev 2011; 25:155-67. [PMID: 21496978 DOI: 10.1016/j.blre.2011.03.002] [Citation(s) in RCA: 272] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
When platelet numbers are low or when their function is disabled, the risk of bleeding is high, which on the one hand indicates that in normal life vascular damage is a rather common event and that hence the role of platelets in maintaining a normal hemostasis is a continuously ongoing physiological process. Upon vascular injury, platelets instantly adhere to the exposed extracellular matrix resulting in platelet activation and aggregation to form a hemostatic plug. This self-amplifying mechanism nevertheless requires a tight control to prevent uncontrolled platelet aggregate formation that eventually would occlude the vessel. Therefore endothelial cells produce inhibitory compounds such as prostacyclin and nitric oxide that limit the growth of the platelet thrombus to the damaged area. With this review, we intend to give an integrated survey of the platelet response to vascular injury in normal hemostasis.
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Affiliation(s)
- Katleen Broos
- Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Campus Kortrijk, Belgium.
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46
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Sigalov AB. The SCHOOL of nature: III. From mechanistic understanding to novel therapies. SELF/NONSELF 2010; 1:192-224. [PMID: 21487477 PMCID: PMC3047783 DOI: 10.4161/self.1.3.12794] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 06/10/2010] [Accepted: 06/11/2010] [Indexed: 11/19/2022]
Abstract
Protein-protein interactions play a central role in biological processes and thus represent an appealing target for innovative drug design and development. They can be targeted by small molecule inhibitors, modulatory peptides and peptidomimetics, which represent a superior alternative to protein therapeutics that carry many disadvantages. Considering that transmembrane signal transduction is an attractive process to therapeutically control multiple diseases, it is fundamentally and clinically important to mechanistically understand how signal transduction occurs. Uncovering specific protein-protein interactions critical for signal transduction, a general platform for receptor-mediated signaling, the signaling chain homooligomerization (SCHOOL) platform, suggests these interactions as universal therapeutic targets. Within the platform, the general principles of signaling are similar for a variety of functionally unrelated receptors. This suggests that global therapeutic strategies targeting key protein-protein interactions involved in receptor triggering and transmembrane signal transduction may be used to treat a diverse set of diseases. This also assumes that clinical knowledge and therapeutic strategies can be transferred between seemingly disparate disorders, such as T cell-mediated skin diseases and platelet disorders or combined to develop novel pharmacological approaches. Intriguingly, human viruses use the SCHOOL-like strategies to modulate and/or escape the host immune response. These viral mechanisms are highly optimized over the millennia, and the lessons learned from viral pathogenesis can be used practically for rational drug design. Proof of the SCHOOL concept in the development of novel therapies for atopic dermatitis, rheumatoid arthritis, cancer, platelet disorders and other multiple indications with unmet needs opens new horizons in therapeutics.
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Abstract
SUMMARY The glycoprotein VI (GPVI)-FcR gamma-chain complex initiates powerful activation of platelets by the subendothelial matrix proteins collagen and laminin through an immunoreceptor tyrosine-based activation motif (ITAM)-regulated signaling pathway. ITAMs are characterized by two YxxL sequences separated by 6-12 amino acids and are found associated with several classes of immunoglobulin (Ig) and C-type lectin receptors in hematopoietic cells, including Fc receptors. Cross-linking of the Ig GPVI leads to phosphorylation of two conserved tyrosines in the FcR gamma-chain ITAM by Src family tyrosine kinases, followed by binding and activation of the tandem SH2 domain-containing Syk tyrosine kinase and stimulation of a downstream signaling cascade that culminates in activation of phospholipase Cgamma2 (PLCgamma2). In contrast, the C-type lectin receptor CLEC-2 mediates powerful platelet activation through Src and Syk kinases, but regulates Syk through a novel dimerization mechanism via a single YxxL motif known as a hemITAM. CLEC-2 is a receptor for podoplanin, which is expressed at high levels in several tissues, including type 1 lung alveolar cells, lymphatic endothelial cells, kidney podocytes and some tumors, but is absent from vascular endothelial cells and platelets. In this article, we compare the mechanism of platelet activation by GPVI and CLEC-2 and consider their functional roles in hemostasis and other vascular processes, including maintenance of vascular integrity, angiogenesis and lymphogenesis.
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Affiliation(s)
- S P Watson
- Centre for Cardiovascular Sciences, Institute for Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.
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48
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Synergism between platelet collagen receptors defined using receptor-specific collagen-mimetic peptide substrata in flowing blood. Blood 2010; 115:5069-79. [PMID: 20351310 DOI: 10.1182/blood-2010-01-260778] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Exposed subendothelial collagen acts as a substrate for platelet adhesion and thrombus formation after vascular injury. Synthetic collagen-derived triple-helical peptides, designated collagen-related peptide (CRP), GFOGER, and VWF-III, can specifically engage the platelet collagen receptors, glycoprotein VI and integrin alpha(2)beta(1), and plasma von Willebrand factor (VWF), respectively. Hitherto, the role of these 3 collagen-binding axes has been studied indirectly. Use of these uniform peptide substrates, rather than collagen fibers, provides independent control of each axis. Here, we use confocal imaging and novel image analysis techniques to investigate the effects of receptor-ligand engagement on platelet binding and activation during thrombus formation under flow conditions. At low shear (100s(-1) and 300s(-1)), both GFOGER and CRP are required for thrombus formation. At 1000s(-1), a combination of either CRP or GFOGER with VWF-III induces comparable thrombus formation, and VWF-III increases thrombus deposition at all shear rates, being indispensable at 3000s(-1). A combination of CRP and VWF-III is sufficient to support extensive platelet deposition at 3000s(-1), with slight additional effect of GFOGER. Measurement of thrombus height after specific receptor blockade or use of altered proportions of peptides indicates a signaling rather than adhesive role for glycoprotein VI, and primarily adhesive roles for both alpha(2)beta(1) and the VWF axis.
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Sigalov AB. The SCHOOL of nature: I. Transmembrane signaling. SELF/NONSELF 2010; 1:4-39. [PMID: 21559175 PMCID: PMC3091606 DOI: 10.4161/self.1.1.10832] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 11/30/2009] [Accepted: 12/01/2009] [Indexed: 11/19/2022]
Abstract
Receptor-mediated transmembrane signaling plays an important role in health and disease. Recent significant advances in our understanding of the molecular mechanisms linking ligand binding to receptor activation revealed previously unrecognized striking similarities in the basic structural principles of function of numerous cell surface receptors. In this work, I demonstrate that the Signaling Chain Homooligomerization (SCHOOL)-based mechanism represents a general biological mechanism of transmembrane signal transduction mediated by a variety of functionally unrelated single- and multichain activating receptors. within the SCHOOL platform, ligand binding-induced receptor clustering is translated across the membrane into protein oligomerization in cytoplasmic milieu. This platform resolves a long-standing puzzle in transmembrane signal transduction and reveals the major driving forces coupling recognition and activation functions at the level of protein-protein interactions-biochemical processes that can be influenced and controlled. The basic principles of transmembrane signaling learned from the SCHOOL model can be used in different fields of immunology, virology, molecular and cell biology and others to describe, explain and predict various phenomena and processes mediated by a variety of functionally diverse and unrelated receptors. Beyond providing novel perspectives for fundamental research, the platform opens new avenues for drug discovery and development.
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Affiliation(s)
- Alexander B Sigalov
- Department of Pathology; University of Massachusetts Medical School; Worcester, MA USA
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50
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Affiliation(s)
- A B Herr
- Department of Molecular Genetics, Biochemistry & Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0524, USA.
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