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Frelinger AL. Flow Cytometry and Platelets. Clin Lab Med 2024; 44:511-526. [PMID: 39089755 DOI: 10.1016/j.cll.2024.04.011] [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] [Indexed: 08/04/2024]
Abstract
Clinical assessment of platelet activation by flow cytometry is useful in the characterization and diagnosis of platelet-specific disorders and as a measure of risk for thrombosis or bleeding. Platelets circulate in a resting, "unactivated" state, but when activated they undergo alterations in surface glycoprotein function and/or expression level, exposure of granule membrane proteins, and exposure of procoagulant phospholipids. Flow cytometry provides the means to detect these changes and, unlike other platelet tests, is appropriate for measuring platelet function in samples from patients with low platelet counts. The present review will focus on flow cytometric tests for platelet activation markers.
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Affiliation(s)
- Andrew L Frelinger
- Center for Platelet Research Studies, Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115-5737, USA.
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2
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Obermann WMJ, König S, Feickert MK, Sanz-Soler R, Eble JA. A change of rhodocytin's suprastructure turns the agonist into an antagonist of tumor cell induced platelet aggregation. FASEB J 2024; 38:e23402. [PMID: 38193585 DOI: 10.1096/fj.202301175r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 12/11/2023] [Accepted: 12/18/2023] [Indexed: 01/10/2024]
Abstract
Cancer cells circulating in the blood attach to platelets by direct cell-cell interactions via several receptor-counterreceptor contacts and indirectly by fibrin bridges which connect the two cell types by distinct integrin receptors. In the microenvironment of these tumor cell platelet aggregates (TCPAs), the tumor cells are shielded from the shear stress of the blood flow and from attack by the immune system. This supports hematogenous metastasis and tumor cell induced thrombosis. Platelet activation is triggered by binding of podoplanin on cancer cells to the platelet receptor Clec-2. Therefore, we hypothesize that targeting this initial step will prevent the entire cascade leading to the formation of TCPAs. Rhodocytin, a heterodimeric (αβ)2 C-type lectin from the Malayan pit viper Calloselasma rhodostoma, binds to Clec-2 and thereby induces TCPA formation. Remarkably, mutations in rhodocytin that disturbed formation of oligomers, blocked the podoplanin-Clec-2 axis and prevented platelet activation. Therefore, we used lysine reactive chemicals to modify rhodocytin isolated from the crude snake venom. Blue native gel electrophoresis and far western blotting showed a change of rhodocytin's suprastructure triggered by acetylation and PEGylation. Mass spectrometry analysis of altered lysines suggested that their modifications interfered with the formation of rhodocytin tetramers. When tested in assays for tumor cell induced platelet aggregation, we found that derivatization turned rhodocytin from an agonist into an antagonist. This observation indicates that Clec-2 is a valid target receptor molecule to curb TCPA formation and to prevent hematogenous metastasis and tumor cell induced thrombosis in cancer patients.
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Affiliation(s)
- Wolfgang M J Obermann
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany
| | | | - Mascha K Feickert
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany
| | - Raquel Sanz-Soler
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany
| | - Johannes A Eble
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany
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3
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Martin EM, Clark JC, Montague SJ, Morán LA, Di Y, Bull LJ, Whittle L, Raka F, Buka RJ, Zafar I, Kardeby C, Slater A, Watson SP. Trivalent nanobody-based ligands mediate powerful activation of GPVI, CLEC-2, and PEAR1 in human platelets whereas FcγRIIA requires a tetravalent ligand. J Thromb Haemost 2024; 22:271-285. [PMID: 37813196 DOI: 10.1016/j.jtha.2023.09.026] [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: 08/07/2023] [Revised: 09/19/2023] [Accepted: 09/27/2023] [Indexed: 10/11/2023]
Abstract
BACKGROUND Clustering of the receptors glycoprotein receptor VI (GPVI), C-type lectin-like receptor 2 (CLEC-2), low-affinity immunoglobulin γ Fc region receptor II-a (FcγRIIA), and platelet endothelial aggregation receptor 1 (PEAR1) leads to powerful activation of platelets through phosphorylation of tyrosine in their cytosolic tails and initiation of downstream signaling cascades. GPVI, CLEC-2, and FcγRIIA signal through YxxL motifs that activate Syk. PEAR1 signals through a YxxM motif that activates phosphoinositide 3-kinase. Current ligands for these receptors have an undefined valency and show significant batch variation and, for some, uncertain specificity. OBJECTIVES We have raised nanobodies against each of these receptors and multimerized them to identify the minimum number of epitopes to achieve robust activation of human platelets. METHODS Divalent and trivalent nanobodies were generated using a flexible glycine-serine linker. Tetravalent nanobodies utilize a mouse Fc domain (IgG2a, which does not bind to FcγRIIA) to dimerize the divalent nanobody. Ligand affinity measurements were determined by surface plasmon resonance. Platelet aggregation, adenosine triphosphate secretion, and protein phosphorylation were analyzed using standardized methods. RESULTS Multimerization of the nanobodies led to a stepwise increase in affinity with divalent and higher-order nanobody oligomers having sub-nanomolar affinity. The trivalent nanobodies to GPVI, CLEC-2, and PEAR1 stimulated powerful and robust platelet aggregation, secretion, and protein phosphorylation at low nanomolar concentrations. A tetravalent nanobody was required to activate FcγRIIA with the concentration-response relationship showing a greater variability and reduced sensitivity compared with the other nanobody-based ligands, despite a sub-nanomolar binding affinity. CONCLUSION The multivalent nanobodies represent a series of standardized, potent agonists for platelet glycoprotein receptors. They have applications as research tools and in clinical assays.
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Affiliation(s)
- Eleyna M Martin
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, UK.
| | - Joanne C Clark
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, UK; Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK
| | - Samantha J Montague
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Luis A Morán
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Ying Di
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Lily J Bull
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Luke Whittle
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Florije Raka
- Institute for Transfusion Medicine-Skopje, Skopje, North Macedonia
| | - Richard J Buka
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Idrees Zafar
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Caroline Kardeby
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, UK; Current address: School of Biosciences, College of Health and Life Sciences, Aston University, Birmingham, UK
| | - Alexandre Slater
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Steve P Watson
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, UK; Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK.
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4
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Clark JC, Martin EM, Morán LA, Di Y, Wang X, Zuidscherwoude M, Brown HC, Kavanagh DM, Hummert J, Eble JA, Nieswandt B, Stegner D, Pollitt AY, Herten DP, Tomlinson MG, García A, Watson SP. Divalent nanobodies to platelet CLEC-2 can serve as agonists or antagonists. Commun Biol 2023; 6:376. [PMID: 37029319 PMCID: PMC10082178 DOI: 10.1038/s42003-023-04766-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 03/27/2023] [Indexed: 04/09/2023] Open
Abstract
CLEC-2 is a target for a new class of antiplatelet agent. Clustering of CLEC-2 leads to phosphorylation of a cytosolic YxxL and binding of the tandem SH2 domains in Syk, crosslinking two receptors. We have raised 48 nanobodies to CLEC-2 and crosslinked the most potent of these to generate divalent and tetravalent nanobody ligands. Fluorescence correlation spectroscopy (FCS) was used to show that the multivalent nanobodies cluster CLEC-2 in the membrane and that clustering is reduced by inhibition of Syk. Strikingly, the tetravalent nanobody stimulated aggregation of human platelets, whereas the divalent nanobody was an antagonist. In contrast, in human CLEC-2 knock-in mouse platelets, the divalent nanobody stimulated aggregation. Mouse platelets express a higher level of CLEC-2 than human platelets. In line with this, the divalent nanobody was an agonist in high-expressing transfected DT40 cells and an antagonist in low-expressing cells. FCS, stepwise photobleaching and non-detergent membrane extraction show that CLEC-2 is a mixture of monomers and dimers, with the degree of dimerisation increasing with expression thereby favouring crosslinking of CLEC-2 dimers. These results identify ligand valency, receptor expression/dimerisation and Syk as variables that govern activation of CLEC-2 and suggest that divalent ligands should be considered as partial agonists.
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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, Edgbaston, Birmingham, B15 2TT, UK.
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK.
| | - Eleyna M Martin
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Luis A Morán
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, 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), Santiago de Compostela, Spain
| | - Ying Di
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Xueqing Wang
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, 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), Santiago de Compostela, Spain
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Malou Zuidscherwoude
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK
| | - Helena C Brown
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Institute of Experimental Biomedicine I, University Hospital and Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Deirdre M Kavanagh
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 QU3, UK
| | - Johan Hummert
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK
| | - Johannes A Eble
- Institute for Physiological Chemistry & Pathobiochemistry, University of Münster, Waldeyerstraße 15, 48149, Münster, Germany
| | - Bernhard Nieswandt
- Institute of Experimental Biomedicine I, University Hospital and Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - David Stegner
- Institute of Experimental Biomedicine I, University Hospital and Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Alice Y Pollitt
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, RG6 6AS, UK
| | - Dirk-Peter Herten
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK
| | - Michael G Tomlinson
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Angel García
- Centre for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade de Santiago de Compostela, and Instituto de Investigación Sanitaria de Santiago (IDIS), Santiago de Compostela, Spain
| | - Steve P Watson
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK.
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5
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Feickert MK, Sanz-Soler R, Niland S, König S, Eble JA, Obermann WMJ. Stimulation of platelet aggregation by affinity captured rhodocytin from the Malayan pit viper Calloselasma rhodostoma. Toxicon 2023; 225:107058. [PMID: 36806336 DOI: 10.1016/j.toxicon.2023.107058] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 02/07/2023] [Accepted: 02/16/2023] [Indexed: 02/19/2023]
Abstract
The receptor protein CLEC-2 on platelet membranes is the target of the endogenous ligand podoplanin found on cancer cells and of rhodocytin, a snake venom component of the Malayan pit viper Calloselasma rhodostoma. Ligand binding results in platelet activation, increased blood coagulation and thrombosis. In an effort to isolate rhodocytin, we have purified CLEC-2 as bait from E. coli. Affinity captured rhodocytin interacted with mammalian CLEC-2 and stimulated platelet aggregation in a dose dependent manner.
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Affiliation(s)
- Mascha K Feickert
- University of Münster, Institute of Physiological Chemistry and Pathobiochemistry, Waldeyerstr. 15, 48149, Münster, Germany
| | - Raquel Sanz-Soler
- University of Münster, Institute of Physiological Chemistry and Pathobiochemistry, Waldeyerstr. 15, 48149, Münster, Germany
| | - Stephan Niland
- University of Münster, Institute of Physiological Chemistry and Pathobiochemistry, Waldeyerstr. 15, 48149, Münster, Germany
| | - Simone König
- IZKF Core Unit Proteomics, Röntgenstr. 21, 48149, Münster, Germany
| | - Johannes A Eble
- University of Münster, Institute of Physiological Chemistry and Pathobiochemistry, Waldeyerstr. 15, 48149, Münster, Germany
| | - Wolfgang M J Obermann
- University of Münster, Institute of Physiological Chemistry and Pathobiochemistry, Waldeyerstr. 15, 48149, Münster, Germany.
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Morán LA, Di Y, Sowa MA, Hermida-Nogueira L, Barrachina MN, Martin E, Clark JC, Mize TH, Eble JA, Moreira D, Pollitt AY, Loza MI, Domínguez E, Watson SP, García Á. Katacine Is a New Ligand of CLEC-2 that Acts as a Platelet Agonist. Thromb Haemost 2022; 122:1361-1368. [PMID: 35170009 PMCID: PMC9393086 DOI: 10.1055/a-1772-1069] [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] [Indexed: 10/29/2022]
Abstract
BACKGROUND CLEC-2 is a platelet receptor with an important role in thromboinflammation but a minor role in hemostasis. Two endogenous ligands of CLEC-2 have been identified, the transmembrane protein podoplanin and iron-containing porphyrin hemin, which is formed following hemolysis from red blood cells. Other exogenous ligands such as rhodocytin have contributed to our understanding of the role of CLEC-2. OBJECTIVES To identify novel CLEC-2 small-molecule ligands to aid therapeutic targeting of CLEC-2. METHODS ALPHA screen technology has been used for the development of a high-throughput screening (HTS) assay recapitulating the podoplanin-CLEC-2 interaction. Light transmission aggregometry was used to evaluate platelet aggregation. Immunoprecipitation and western blot were used to evaluate direct phosphorylation of CLEC-2 and downstream protein phosphorylation. Autodock vina software was used to predict the molecular binding site of katacine and mass spectrometry to determine the polymeric nature of the ligand. RESULTS AND CONCLUSION We developed a CLEC-2-podoplanin interaction assay in a HTS format and screened 5,016 compounds from a European Union-open screen library. We identified katacine, a mixture of polymers of proanthocyanidins, as a novel ligand for CLEC-2 and showed that it induces platelet aggregation and CLEC-2 phosphorylation via Syk and Src kinases. Platelet aggregation induced by katacine is inhibited by the anti-CLEC-2 monoclonal antibody fragment AYP1 F(ab)'2. Katacine is a novel nonprotein ligand of CLEC-2 that could contribute to a better understanding of CLEC-2 activation in human platelets.
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Affiliation(s)
- Luis A Morán
- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade de Santiago de Compostela, and Instituto de Investigación Sanitaria de Santiago (IDIS), Santiago de Compostela, Spain.,Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Ying Di
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Marcin A Sowa
- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade de Santiago de Compostela, and Instituto de Investigación Sanitaria de Santiago (IDIS), Santiago de Compostela, Spain.,Institute for Cardiovascular and Metabolic Research (ICMR), School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Lidia Hermida-Nogueira
- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade de Santiago de Compostela, and Instituto de Investigación Sanitaria de Santiago (IDIS), Santiago de Compostela, Spain
| | - María N Barrachina
- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade de Santiago de Compostela, and Instituto de Investigación Sanitaria de Santiago (IDIS), Santiago de Compostela, Spain
| | - Eleyna Martin
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Joanne C Clark
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Todd H Mize
- Advanced Mass Spectrometry Facility, Biosciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Johannes A Eble
- Institute for Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany
| | - David Moreira
- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade de Santiago de Compostela, and Instituto de Investigación Sanitaria de Santiago (IDIS), Santiago de Compostela, Spain
| | - Alice Y Pollitt
- Institute for Cardiovascular and Metabolic Research (ICMR), School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - María I Loza
- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade de Santiago de Compostela, and Instituto de Investigación Sanitaria de Santiago (IDIS), Santiago de Compostela, Spain
| | - Eduardo Domínguez
- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade de Santiago de Compostela, and Instituto de Investigación Sanitaria de Santiago (IDIS), Santiago de Compostela, Spain
| | - Steve P Watson
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Ángel García
- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade de Santiago de Compostela, and Instituto de Investigación Sanitaria de Santiago (IDIS), Santiago de Compostela, Spain
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Dohnálek J, Skálová T. C-type lectin-(like) fold - Protein-protein interaction patterns and utilization. Biotechnol Adv 2022; 58:107944. [PMID: 35301089 DOI: 10.1016/j.biotechadv.2022.107944] [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: 10/02/2021] [Revised: 03/04/2022] [Accepted: 03/07/2022] [Indexed: 11/02/2022]
Abstract
The C-type lectin-like fold (CTL fold) is a building block of many proteins, including saccharide-binding lectins, natural killer cell receptors, macrophage mannose receptor, selectins, collectins, snake venoms and others. Some are important players in innate immunity and are involved in the first-line response to virally infected cells or cancer cells, some play a role in antimicrobial defense, and some are potential targets for fight against problems connected with allergies, obesity, and autoimmunity. The structure of a CTL domain typically contains two α-helices, two small β-sheets and a long surface loop, with two or three disulfide bridges stabilizing the structure. This small domain is often involved in interactions with a target molecule, however, utilizing varied parts of the domain surface, with or without structural modifications. More than 500 three-dimensional structures of CTL fold-containing proteins are available in the Protein Data Bank, including a significant number of complexes with their key interacting partners (protein:protein complexes). The amount of available structural data enables a detailed analysis of the rules of interaction patterns utilized in activation, inhibition, attachment and other pathways or functionalities. Interpretation of known CTL receptor structures and all other CTL-containing proteins and complexes with described three-dimensional structures, complemented with sequence/structure/interaction correlation analysis offers a comprehensive view of the rules of interaction patterns of the CTL fold. The results are of value for prediction of interaction behavior of so far not understood CTL-containing proteins and development of new protein binders based on this fold, with applications in biomedicine or biotechnologies. It follows from the available structural data that almost the whole surface of the CTL fold is utilized in protein:protein interactions, with the heaviest frequency of utilization in the canonical interaction region. The individual categories of interactions differ in the interface buildup strategy. The strongest CTL binders rely on interfaces with large interaction area, presence of hydrophobic core, or high surface complementarity. The typical interaction surfaces of the fold are not conserved in amino acid sequence and can be utilized in design of new binders for biotechnological applications.
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Affiliation(s)
- Jan Dohnálek
- Institute of Biotechnology of the Czech Academy of Sciences, Biocev, Průmyslová 595, 25250 Vestec, Czech Republic.
| | - Tereza Skálová
- Institute of Biotechnology of the Czech Academy of Sciences, Biocev, Průmyslová 595, 25250 Vestec, Czech Republic
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8
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Martin EM, Zuidscherwoude M, Morán LA, Di Y, García A, Watson SP. The structure of CLEC-2: mechanisms of dimerization and higher-order clustering. Platelets 2021; 32:733-743. [PMID: 33819136 DOI: 10.1080/09537104.2021.1906407] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 03/04/2021] [Accepted: 03/16/2021] [Indexed: 02/07/2023]
Abstract
The platelet C-type lectin-like receptor CLEC-2 drives inflammation-driven venous thrombosis in mouse models of thrombo-inflammatory disease with a minimal effect on hemostasis identifying it as a target for a new class of antiplatelet agent. Here, we discuss how the protein structure and dynamic arrangement of CLEC-2 on the platelet membrane helps the receptor, which has a single YxxL motif (known as a hemITAM), to trigger intracellular signaling. CLEC-2 exists as a monomer and homo-dimer within resting platelets and forms higher-order oligomers following ligand activation, a process that is mediated by the multivalent nature of its ligands and the binding of the tandem SH2 domains of Syk to the phosphorylated hemITAM and concomitantly to PIP2 or PIP3 to localize it to the membrane. We propose that a low level of active Syk is present at the membrane in resting platelets due to phosphorylation by Src family kinases and that clustering of receptors disturbs the equilibrium between kinases and phosphatases, triggering phosphorylation of the CLEC-2 hemITAM and recruitment of Syk. Knowledge of the structure of CLEC-2 and the mechanism of platelet activation has important implications for development of therapeutics.
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Affiliation(s)
- Eleyna M Martin
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham
| | - Malou Zuidscherwoude
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham
| | - Luis A Morán
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham
- Centre for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade De Santiago De Compostela, Spain
| | - Ying Di
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham
| | - Angel García
- Centre for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade De Santiago De Compostela, Spain
| | - Steve P Watson
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, The Midlands
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9
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Obermann WMJ, Brockhaus K, Eble JA. Platelets, Constant and Cooperative Companions of Sessile and Disseminating Tumor Cells, Crucially Contribute to the Tumor Microenvironment. Front Cell Dev Biol 2021; 9:674553. [PMID: 33937274 PMCID: PMC8085416 DOI: 10.3389/fcell.2021.674553] [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] [Received: 03/01/2021] [Accepted: 03/29/2021] [Indexed: 12/12/2022] Open
Abstract
Although platelets and the coagulation factors are components of the blood system, they become part of and contribute to the tumor microenvironment (TME) not only within a solid tumor mass, but also within a hematogenous micrometastasis on its way through the blood stream to the metastatic niche. The latter basically consists of blood-borne cancer cells which are in close association with platelets. At the site of the primary tumor, the blood components reach the TME via leaky blood vessels, whose permeability is increased by tumor-secreted growth factors, by incomplete angiogenic sprouts or by vasculogenic mimicry (VM) vessels. As a consequence, platelets reach the primary tumor via several cell adhesion molecules (CAMs). Moreover, clotting factor VII from the blood associates with tissue factor (TF) that is abundantly expressed on cancer cells. This extrinsic tenase complex turns on the coagulation cascade, which encompasses the activation of thrombin and conversion of soluble fibrinogen into insoluble fibrin. The presence of platelets and their release of growth factors, as well as fibrin deposition changes the TME of a solid tumor mass substantially, thereby promoting tumor progression. Disseminating cancer cells that circulate in the blood stream also recruit platelets, primarily by direct cell-cell interactions via different receptor-counterreceptor pairs and indirectly by fibrin, which bridges the two cell types via different integrin receptors. These tumor cell-platelet aggregates are hematogenous micrometastases, in which platelets and fibrin constitute a particular TME in favor of the cancer cells. Even at the distant site of settlement, the accompanying platelets help the tumor cell to attach and to grow into metastases. Understanding the close liaison of cancer cells with platelets and coagulation factors that change the TME during tumor progression and spreading will help to curb different steps of the metastatic cascade and may help to reduce tumor-induced thrombosis.
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Affiliation(s)
| | | | - Johannes A. Eble
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany
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10
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Expanding the Known Repertoire of C-Type Lectin Receptors Binding to Toxoplasma gondii Oocysts Using a Modified High-Resolution Immunofluorescence Assay. mSphere 2021; 6:6/2/e01341-20. [PMID: 33789945 PMCID: PMC8546727 DOI: 10.1128/msphere.01341-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The environmental stage of the apicomplexan Toxoplasma gondii oocyst is vital to its life cycle but largely understudied. Because oocysts are excreted only by infected felids, their availability for research is limited. We report the adaptation of an agarose-based method to immobilize minute amounts of oocysts to perform immunofluorescence assays. Agarose embedding allows high-resolution confocal microscopy imaging of antibodies binding to the oocyst surface as well as unprecedented imaging of intracellular sporocyst structures with Maclura pomifera agglutinin after on-slide permeabilization of the immobilized oocysts. To identify new possible molecules binding to the oocyst surface, we used this method to screen a library of C-type lectin receptor (CLR)-human IgG constant region fusion proteins from the group of related CLRs called the Dectin-1 cluster against oocysts. In addition to CLEC7A that was previously reported to decorate T. gondii oocysts, we present experimental evidence for specific binding of three additional CLRs to the surface of this stage. We discuss how these CLRs, known to be expressed on neutrophils, dendritic cells, or macrophages, could be involved in the early immune response by the host, such as oocyst antigen uptake in the intestine. In conclusion, we present a modified immunofluorescence assay technique that allows material-saving immunofluorescence microscopy with T. gondii oocysts in a higher resolution than previously published, which allowed us to describe three additional CLRs binding specifically to the oocyst surface. IMPORTANCE Knowledge of oocyst biology of Toxoplasma gondii is limited, not the least due to its limited availability. We describe a method that permits us to process minute amounts of oocysts for immunofluorescence microscopy without compromising their structural properties. This method allowed us to visualize internal structures of sporocysts by confocal microscopy in unprecedented quality. Moreover, the method can be used as a low- to medium-throughput method to screen for molecules interacting with oocysts, such as antibodies, or compounds causing structural damage to oocysts (i.e., disinfectants). Using this method, we screened a small library of C-type lectin receptors (CLRs) present on certain immune cells and found three CLRs able to decorate the oocyst wall of T. gondii and which were not known before to bind to oocysts. These tools will allow further study into oocyst wall composition and could also provoke experiments regarding immunological recognition of oocysts.
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Damaskinaki FN, Moran LA, Garcia A, Kellam B, Watson SP. Overcoming challenges in developing small molecule inhibitors for GPVI and CLEC-2. Platelets 2021; 32:744-752. [PMID: 33406951 DOI: 10.1080/09537104.2020.1863939] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
GPVI and CLEC-2 have emerged as promising targets for long-term prevention of both arterial thrombosis and thrombo-inflammation with a decreased bleeding risk relative to current drugs. However, while there are potent blocking antibodies of both receptors, their protein nature comes with decreased bioavailability, making formulation for oral medication challenging. Small molecules are able to overcome these limitations, but there are many challenges in developing antagonists of nanomolar potency, which is necessary when considering the structural features that underlie the interaction of CLEC-2 and GPVI with their protein ligands. In this review, we describe current small-molecule inhibitors for both receptors and strategies to overcome such limitations, including considerations when it comes to in silico drug design and the importance of complex compound library selection.
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Affiliation(s)
- 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.,Biodiscovery Institute, University Park, University of Nottingham, Nottingham, UK
| | - Luis A Moran
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.,Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidad de Santiago de Compostela, and Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, Spain
| | - Angel Garcia
- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidad de Santiago de Compostela, and Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, Spain
| | - Barrie Kellam
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK.,Biodiscovery Institute, University Park, University of Nottingham, Nottingham, 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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12
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Martyanov AA, Balabin FA, Dunster JL, Panteleev MA, Gibbins JM, Sveshnikova AN. Control of Platelet CLEC-2-Mediated Activation by Receptor Clustering and Tyrosine Kinase Signaling. Biophys J 2020; 118:2641-2655. [PMID: 32396849 DOI: 10.1016/j.bpj.2020.04.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 03/06/2020] [Accepted: 04/13/2020] [Indexed: 02/07/2023] Open
Abstract
Platelets are blood cells responsible for vascular integrity preservation. The activation of platelet receptor C-type lectin-like receptor II-type (CLEC-2) could partially mediate the latter function. Although this receptor is considered to be of importance for hemostasis, the rate-limiting steps of CLEC-2-induced platelet activation are not clear. Here, we aimed to investigate CLEC-2-induced platelet signal transduction using computational modeling in combination with experimental approaches. We developed a stochastic multicompartmental computational model of CLEC-2 signaling. The model described platelet activation beginning with CLEC-2 receptor clustering, followed by Syk and Src family kinase phosphorylation, determined by the cluster size. Active Syk mediated linker adaptor for T cell protein phosphorylation and membrane signalosome formation, which resulted in the activation of Bruton's tyrosine kinase, phospholipase and phosphoinositide-3-kinase, calcium, and phosphoinositide signaling. The model parameters were assessed from published experimental data. Flow cytometry, total internal reflection fluorescence and confocal microscopy, and western blotting quantification of the protein phosphorylation were used for the assessment of the experimental dynamics of CLEC-2-induced platelet activation. Analysis of the model revealed that the CLEC-2 receptor clustering leading to the membrane-based signalosome formation is a critical element required for the accurate description of the experimental data. Both receptor clustering and signalosome formation are among the rate-limiting steps of CLEC-2-mediated platelet activation. In agreement with these predictions, the CLEC-2-induced platelet activation, but not activation mediated by G-protein-coupled receptors, was strongly dependent on temperature conditions and cholesterol depletion. Besides, the model predicted that CLEC-2-induced platelet activation results in cytosolic calcium spiking, which was confirmed by single-platelet total internal reflection fluorescence microscopy imaging. Our results suggest a refined picture of the platelet signal transduction network associated with CLEC-2. We show that tyrosine kinase activation is not the only rate-limiting step in CLEC-2-induced activation of platelets. Translocation of receptor-agonist complexes to the signaling region and linker adaptor for T cell signalosome formation in this region are limiting CLEC-2-induced activation as well.
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Affiliation(s)
- Alexey A Martyanov
- Center for Theoretical Problems of Physico-chemical Pharmacology, Russian Academy of Sciences, Moscow, Russia; Dmitry Rogachev National Medical Research Centre of Pediatric Hematology, Oncology and Immunology, Moscow, Russia; Institute for Biochemical Physics, Russian Academy of Sciences, Moscow, Russia; Faculty of Physics, Lomonosov Moscow State University, Moscow, Russia
| | - Fedor A Balabin
- Center for Theoretical Problems of Physico-chemical Pharmacology, Russian Academy of Sciences, Moscow, Russia; Dmitry Rogachev National Medical Research Centre of Pediatric Hematology, Oncology and Immunology, Moscow, Russia
| | - Joanne L Dunster
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, Harborne Building, University of Reading, Whiteknights, Reading, United Kingdom
| | - Mikhail A Panteleev
- Center for Theoretical Problems of Physico-chemical Pharmacology, Russian Academy of Sciences, Moscow, Russia; Dmitry Rogachev National Medical Research Centre of Pediatric Hematology, Oncology and Immunology, Moscow, Russia; Faculty of Physics, Lomonosov Moscow State University, Moscow, Russia; Faculty of Biological and Medical Physics, Moscow Institute of Physics and Technology, Dolgoprudnyi, Russia
| | - Jonathan M Gibbins
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, Harborne Building, University of Reading, Whiteknights, Reading, United Kingdom
| | - Anastasia N Sveshnikova
- Center for Theoretical Problems of Physico-chemical Pharmacology, Russian Academy of Sciences, Moscow, Russia; Dmitry Rogachev National Medical Research Centre of Pediatric Hematology, Oncology and Immunology, Moscow, Russia; Faculty of Physics, Lomonosov Moscow State University, Moscow, Russia; Department of Normal Physiology, Sechenov First Moscow State Medical University, Moscow, Russia.
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13
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Snake venom rhodocytin induces plasma extravasation via toxin-mediated interactions between platelets and mast cells. Sci Rep 2019; 9:15958. [PMID: 31685912 PMCID: PMC6828706 DOI: 10.1038/s41598-019-52449-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 10/17/2019] [Indexed: 12/13/2022] Open
Abstract
Venomous snakebites can induce local tissue damage, including necrosis of soft tissues, haemorrhage, blistering and local swelling associated with plasma extravasation, which can lead to lethal complications such as hypovolemic shock. However, the details of the underlying mechanisms remain unknown. In this study, we showed that intradermal treatment of mice with venom rhodocytin from the Malayan viper Calloselasma rhodostoma induced plasma extravasation, dependent on C-type lectin-like receptor 2 (CLEC-2) on platelets. Rhodocytin-induced plasma extravasation also relied on mast cells and histamine. In vitro co-culture of rhodocytin-activated platelets with mast cells induced histamine release from mast cells in an ATP/P2X7-dependent manner. Consistent with this, blockade or deficiency of P2X7 in mast cells suppressed rhodocytin-induced plasma extravasation in the skin. Together, these findings indicate that rhodocytin induces plasma extravasation by triggering platelet activation via CLEC-2, followed by activation of mast cells and histamine release via the ATP/P2X7 pathway. These results reveal a previously unrecognized mechanism by which snake venom increases vascular permeability via complex venom toxin–mediated interactions between platelets and mast cells.
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14
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Cobalt hematoporphyrin inhibits CLEC-2-podoplanin interaction, tumor metastasis, and arterial/venous thrombosis in mice. Blood Adv 2019; 2:2214-2225. [PMID: 30190281 DOI: 10.1182/bloodadvances.2018016261] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 08/13/2018] [Indexed: 01/26/2023] Open
Abstract
The platelet activation receptor C-type lectin-like receptor 2 (CLEC-2) interacts with podoplanin on the surface of certain types of tumor cells, and this interaction facilitates tumor metastasis. CLEC-2 is also involved in thrombus formation and its stabilization. Because CLEC-2-depleted mice are protected from experimental lung metastasis and thrombus formation and do not show increased bleeding time, CLEC-2 may serve as a good target for antimetastatic or antithrombotic drugs. We screened 6770 compounds for their capability to inhibit CLEC-2-podoplanin binding using an enzyme-linked immunosorbent assay. In the first screening round, 63 compounds were identified and further evaluated by flow cytometry using CLEC-2-expressing cells. We identified protoporphyrin IX (H2-PP) as the most potent inhibitor and modified its hematoporphyrin moiety to be complexed with cobalt (cobalt hematoporphyrin [Co-HP]), which resulted in an inhibitory potency much stronger than that of H2-PP. Surface plasmon resonance analysis and molecular docking study showed that Co-HP binds directly to CLEC-2 at N120, N210, and K211, previously unknown podoplanin-binding sites; this binding was confirmed by analysis of CLEC-2 mutants with alterations in N120 and/or K211. Co-HP at a concentration of 1.53 μM inhibited platelet aggregation mediated through CLEC-2, but not that mediated through other receptors. IV administration of Co-HP to mice significantly inhibited hematogenous metastasis of podoplanin-expressing B16F10 cells to the lung as well as in vivo arterial and venous thrombosis, without a significant increase in tail-bleeding time. Thus, Co-HP may be a promising molecule for antimetastatic and antiplatelet treatment that does not cause bleeding tendency.
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15
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Martyanov AA, Kaneva VN, Panteleev MA, Sveshnikova AN. [CLEC-2 induced signalling in blood platelets]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2019; 64:387-396. [PMID: 30378555 DOI: 10.18097/pbmc20186405387] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Platelet activating receptor CLEC-2 has been identified on platelet surface a decade ago. The only confirmed endogenous CLEC-2 agonist is podoplanin. Podoplanin is a transmembrane protein expressed by lymphatic endothelial cells, reticular fibroblastic cells in lymph nodes, kidney podocytes and by cells of certain tumors. CLEC-2 and podoplanin are involved in the processes of embryonic development (blood-lymph vessel separation and angiogenesis), maintaining of vascular integrity of small vessels during inflammation and prevention of blood-lymphatic mixing in high endothelial venules. However, CLEC-2 and podoplanin are contributing to tumor methastasis progression, Salmonella sepsis, deep-vein thrombosis. CLEC-2 signalling cascade includes tyrosine-kinases (Syk, SFK, Btk) as well as adapter LAT and phospholipase Cg2, which induces calcium signalling. CLEC-2, podoplanin and proteins, participating in CLEC-2 signalling cascade, are perspective targets for antithrombotic therapy.
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Affiliation(s)
- A A Martyanov
- Faculty of Physics, Lomonosov Moscow State University, Moscow, Russia; Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia
| | - V N Kaneva
- Faculty of Physics, Lomonosov Moscow State University, Moscow, Russia; Rogachev National Scientific and Practical Centre of Pediatric Hematology, Oncology and Immunology, Moscow, Russia
| | - M A Panteleev
- Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia; Rogachev National Scientific and Practical Centre of Pediatric Hematology, Oncology and Immunology, Moscow, Russia
| | - A N Sveshnikova
- Faculty of Physics, Lomonosov Moscow State University, Moscow, Russia; Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia
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16
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Eble JA. Structurally Robust and Functionally Highly Versatile-C-Type Lectin (-Related) Proteins in Snake Venoms. Toxins (Basel) 2019; 11:toxins11030136. [PMID: 30823637 PMCID: PMC6468738 DOI: 10.3390/toxins11030136] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 02/19/2019] [Accepted: 02/20/2019] [Indexed: 12/31/2022] Open
Abstract
Snake venoms contain an astounding variety of different proteins. Among them are numerous C-type lectin family members, which are grouped into classical Ca2+- and sugar-binding lectins and the non-sugar-binding snake venom C-type lectin-related proteins (SV-CLRPs), also called snaclecs. Both groups share the robust C-type lectin domain (CTLD) fold but differ in a long loop, which either contributes to a sugar-binding site or is expanded into a loop-swapping heterodimerization domain between two CLRP subunits. Most C-type lectin (-related) proteins assemble in ordered supramolecular complexes with a high versatility of subunit numbers and geometric arrays. Similarly versatile is their ability to inhibit or block their target molecules as well as to agonistically stimulate or antagonistically blunt a cellular reaction triggered by their target receptor. By utilizing distinct interaction sites differentially, SV-CLRPs target a plethora of molecules, such as distinct coagulation factors and receptors of platelets and endothelial cells that are involved in hemostasis, thrombus formation, inflammation and hematogenous metastasis. Because of their robust structure and their high affinity towards their clinically relevant targets, SV-CLRPs are and will potentially be valuable prototypes to develop new diagnostic and therapeutic tools in medicine, provided that the molecular mechanisms underlying their versatility are disclosed.
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Affiliation(s)
- Johannes A Eble
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Waldeyerstr. 15, 48149 Münster, Germany.
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17
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Kostyak JC, Mauri BR, Dangelmaier C, Patel A, Zhou Y, Eble JA, Tsygankov AY, McKenzie SE, Kunapuli SP. TULA-2 Deficiency Enhances Platelet Functional Responses to CLEC-2 Agonists. TH OPEN 2018; 2:e411-e419. [PMID: 31249969 PMCID: PMC6524918 DOI: 10.1055/s-0038-1676358] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Accepted: 10/10/2018] [Indexed: 02/06/2023] Open
Abstract
Platelet activation is essential for hemostasis. Central to platelet activation are the signals transmitted through surface receptors such as glycoprotein VI, the protease-activated receptors, and C-type lectin-like receptor 2 (CLEC-2). CLEC-2 is a HemITAM (hem-immunoreceptor tyrosine activation motif)-bearing receptor that binds podoplanin and signals through spleen tyrosine kinase (Syk). T-cell ubiquitin ligand-2 (TULA-2) is a protein tyrosine phosphatase that is highly expressed in platelets and targets phosphorylated Y352 of Syk. We wanted to determine whether TULA-2 regulates Syk phosphorylation and activity downstream of CLEC-2. To that end, we used TULA-2 knockout mice and wild-type (WT) littermate controls. We found that TULA-2 deficiency enhances the aggregation and secretion response following stimulation with an excitatory CLEC-2 antibody or the CLEC-2 agonist rhodocytin. Consistently, Syk phosphorylation of Y346 is enhanced, as well as phosphorylation of the downstream signaling molecule PLCγ2, in TULA-2 knockout platelets treated with either CLEC-2 antibody or rhodocytin, compared with WT control platelets. Furthermore, the kinetics of Syk phosphorylation, as well as that of PLCγ2 and SLP-76, is enhanced in TULA-2 knockout platelets treated with 2.5-μg/mL CLEC-2 antibody compared with WT platelets. Similarly, thromboxane production was enhanced, in both amount and kinetics, in TULA-2
−/−
platelets treated with 2.5-μg/mL CLEC-2 antibody. TULA-2 acts as a negative regulator of CLEC-2 signaling by dephosphorylating Syk on Y346 and restraining subsequent Syk-mediated signaling.
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Affiliation(s)
- John C Kostyak
- Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
| | - Benjamin R Mauri
- Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
| | - Carol Dangelmaier
- Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
| | - Akruti Patel
- Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
| | - Yuhang Zhou
- Cardeza Foundation for Hematologic Research, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States
| | - Johannes A Eble
- Institute of Physiological Chemistry and Pathobiochemistry, University of Munster, Waldeyerstasse, Munster, Germany
| | - Alexander Y Tsygankov
- Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States.,Department of Immunology and Microbiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
| | - Steven E McKenzie
- Cardeza Foundation for Hematologic Research, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States
| | - Satya P Kunapuli
- Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
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18
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Martyanov AA, Kaneva VN, Panteleev MA, Sveshnikova AN. Physiological and pathophysiological aspects of blood platelet activation through CLEC-2 receptor. ONCOHEMATOLOGY 2018. [DOI: 10.17650/1818-8346-2018-13-3-83-90] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Platelet activating receptor CLEC-2 has been identified on platelet surface a decade ago. The only confirmed endogenous CLEC-2 agonist is podoplanin. Podoplanin is a transmembrane protein expressed by lymphatic endothelial cells, reticular fibroblastic cells in lymph nodes, kidney podocytes and by cells of certain tumors. Association of CLEC-2 with podoplanin is involved in processes of embryonic development (blood-lymph vessel separation and angiogenesis), maintaining of vascular integrity of small vessels during inflammation and prevention of blood-lymphatic mixing in high endothelial venules. However, CLEC-2 and podoplanin are contributing to tumor metastasis progression, Salmonella sepsis and deep-vein thrombosis. This makes CLEC-2 and podoplanin a perspective target for pharmacological treatment. Aspirin and Ibrutinib are considered to be perspective for abrogation of podoplanin-induced platelet activation via CLEC-2. The present review discusses already known pathological and physiological roles of CLEC-2 and possibilities of a targeted therapy for CLEC-2 associated diseases.
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Affiliation(s)
- A. A. Martyanov
- Dmitry Rogachev National Medical Research Centre of Pediatric Hematology, Oncology and Immunology; Lomonosov Moscow State University, Faculty of Physics; Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences
| | - V. N. Kaneva
- Dmitry Rogachev National Medical Research Centre of Pediatric Hematology, Oncology and Immunology; Lomonosov Moscow State University, Faculty of Physics
| | - M. A. Panteleev
- Dmitry Rogachev National Medical Research Centre of Pediatric Hematology, Oncology and Immunology; Lomonosov Moscow State University, Faculty of Physics; Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences; Moscow Institute of Physics and Technology (State University), Faculty of Biological and Medical Physics
| | - A. N. Sveshnikova
- Dmitry Rogachev National Medical Research Centre of Pediatric Hematology, Oncology and Immunology; Lomonosov Moscow State University, Faculty of Physics; Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences
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19
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Sasaki T, Shirai T, Tsukiji N, Otake S, Tamura S, Ichikawa J, Osada M, Satoh K, Ozaki Y, Suzuki-Inoue K. Functional characterization of recombinant snake venom rhodocytin: rhodocytin mutant blocks CLEC-2/podoplanin-dependent platelet aggregation and lung metastasis. J Thromb Haemost 2018; 16:960-972. [PMID: 29488681 DOI: 10.1111/jth.13987] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Indexed: 12/11/2022]
Abstract
Essentials We generated recombinant rhodocytin that could aggregate platelets via CLEC-2. Recombinant wild-type rhodocytin formed heterooctamer with four α- and β-subunits. Asp 4 in α-subunit of rhodocytin was required for binding to CLEC-2. Inhibitory mutant of rhodocytin blocked podoplanin-dependent hematogenous metastasis. SUMMARY Background Rhodocytin, a disulfide-linked heterodimeric C-type lectin from Calloselasma rhodostoma consisting of α-subunits and β-subunits, induces platelet aggregation through C-type lectin-like receptor 2 (CLEC-2). CLEC-2 is a physiological binding partner of podoplanin (PDPN), which is expressed on some tumor cell types, and is involved in tumor cell-induced platelet aggregation and tumor metastasis. Thus, modified rhodocytin may be a possible source of anti-CLEC-2 drugs for both antiplatelet and antimetastasis therapy. However, its molecular function has not been well characterized, because of the lack of recombinant rhodocytin that induces platelet aggregation. Objective To produce recombinant rhodocytin, in order to verify its function with mutagenesis, and to develop an anti-CLEC-2 drug based on the findings. Methods We used Chinese hamster ovary cells to express recombinant rhodocytin (wild-type [WT] and mutant), which was analyzed for induction/inhibition of platelet aggregation with light transmission aggregometry, the formation of multimers with blue native PAGE, and binding to CLEC-2 with flow cytometry. Finally, we investigated whether mutant rhodocytin could suppress PDPN-induced metastasis in an experimental lung metastasis mouse model. Results Functional WT] rhodocytin (αWTβWT) was obtained by coexpression of both subunits. Asp4 in α-subunits of rhodocytin was required for CLEC-2 binding. αWTβWT formed a heterooctamer similarly to native rhodocytin. Moreover, an inhibitory mutant of rhodocytin (αWTβK53A/R56A), forming a heterotetramer, bound to CLEC-2 without inducing platelet aggregation, and blocked CLEC-2-PDPN interaction-dependent platelet aggregation and experimental lung metastasis. Conclusion These findings provide molecular characterization information on rhodocytin, and suggest that mutant rhodocytin could be used as a therapeutic agent to target CLEC-2.
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Affiliation(s)
- T Sasaki
- Department of Clinical and Laboratory Medicine, Faculty of Medicine, University of Yamanashi, Kofu, Japan
| | - T Shirai
- Department of Clinical and Laboratory Medicine, Faculty of Medicine, University of Yamanashi, Kofu, Japan
| | - N Tsukiji
- Department of Clinical and Laboratory Medicine, Faculty of Medicine, University of Yamanashi, Kofu, Japan
| | | | - S Tamura
- Department of Pathophysiological Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - J Ichikawa
- Department of Orthopedic Surgery, Faculty of Medicine, University of Yamanashi, Kofu, Japan
| | - M Osada
- School of Medical Technology, Gunma Paz University, Takasaki, Japan
| | - K Satoh
- Division of Laboratory Medicine, University of Yamanashi Hospital, Kofu, Japan
| | - Y Ozaki
- Fuefuki Central Hospital, Fuefuki, Japan
| | - K Suzuki-Inoue
- Department of Clinical and Laboratory Medicine, Faculty of Medicine, University of Yamanashi, Kofu, Japan
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20
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Badolia R, Inamdar V, Manne BK, Dangelmaier C, Eble JA, Kunapuli SP. G q pathway regulates proximal C-type lectin-like receptor-2 (CLEC-2) signaling in platelets. J Biol Chem 2017; 292:14516-14531. [PMID: 28705934 DOI: 10.1074/jbc.m117.791012] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 07/09/2017] [Indexed: 11/06/2022] Open
Abstract
Platelets play a key role in the physiological hemostasis or pathological process of thrombosis. Rhodocytin, an agonist of the C-type lectin-like receptor-2 (CLEC-2), elicits powerful platelet activation signals in conjunction with Src family kinases (SFKs), spleen tyrosine kinase (Syk), and phospholipase γ2 (PLCγ2). Previous reports have shown that rhodocytin-induced platelet aggregation depends on secondary mediators such as thromboxane A2 (TxA2) and ADP, which are agonists for G-protein-coupled receptors (GPCRs) on platelets. How the secondary mediators regulate CLEC-2-mediated platelet activation in terms of signaling is not clearly defined. In this study, we report that CLEC-2-induced Syk and PLCγ2 phosphorylation is potentiated by TxA2 and that TxA2 plays a critical role in the most proximal event of CLEC-2 signaling, i.e. the CLEC-2 receptor tyrosine phosphorylation. We show that the activation of other GPCRs, such as the ADP receptors and protease-activated receptors, can also potentiate CLEC-2 signaling. By using the specific Gq inhibitor, UBO-QIC, or Gq knock-out murine platelets, we demonstrate that Gq signaling, but not other G-proteins, is essential for GPCR-induced potentiation of Syk phosphorylation downstream of CLEC-2. We further elucidated the signaling downstream of Gq and identified an important role for the PLCβ-PKCα pathway, possibly regulating activation of SFKs, which are crucial for initiation of CLEC-2 signaling. Together, these results provide evidence for novel Gq-PLCβ-PKCα-mediated regulation of proximal CLEC-2 signaling by Gq-coupled receptors.
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Affiliation(s)
- Rachit Badolia
- From the Department of Physiology.,Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140 and
| | - Vaishali Inamdar
- From the Department of Physiology.,Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140 and
| | - Bhanu Kanth Manne
- From the Department of Physiology.,Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140 and
| | - Carol Dangelmaier
- From the Department of Physiology.,Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140 and
| | - Johannes A Eble
- the Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Waldeyerstrasse 15, 48149 Münster, Germany
| | - Satya P Kunapuli
- From the Department of Physiology, .,Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140 and
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Manne BK, Badolia R, Dangelmaier CA, Kunapuli SP. C-type lectin like receptor 2 (CLEC-2) signals independently of lipid raft microdomains in platelets. Biochem Pharmacol 2014; 93:163-70. [PMID: 25462818 DOI: 10.1016/j.bcp.2014.11.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 11/05/2014] [Accepted: 11/12/2014] [Indexed: 10/24/2022]
Abstract
C-type lectin like receptor 2 (CLEC-2) has been reported to activate platelets through a lipid raft-dependent manner. Secreted ADP potentiates CLEC-2-mediated platelet aggregation. We have investigated whether the decrease in CLEC-2-mediated platelet aggregation, previously reported in platelets with disrupted rafts, is a result of the loss of agonist potentiation by ADP. We disrupted platelet lipid rafts with methyl-β-cyclodextrin (MβCD) and measured signaling events downstream of CLEC-2 activation. Lipid raft disruption decreases platelet aggregation induced by CLEC-2 agonists. The inhibition of platelet aggregation by the disruption of lipid rafts was rescued by the exogenous addition of epinephrine but not 2-methylthioadenosine diphosphate (2MeSADP), which suggests that lipid raft disruption effects P2Y12-mediated Gi activation but not Gz. Phosphorylation of Syk (Y525/526) and PLCγ2 (Y759), were not affected by raft disruption in CLEC-2 agonist-stimulated platelets. Furthermore, tyrosine phosphorylation of the CLEC-2 hemi-ITAM was not effected when MβCD disrupts lipid rafts. Lipid rafts do not directly contribute to CLEC-2 receptor activation in platelets. The effects of disruption of lipid rafts in in vitro assays can be attributed to inhibition of ADP feedback that potentiates CLEC-2 signaling.
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Affiliation(s)
- Bhanu Kanth Manne
- Department of Physiology, Temple University School of Medicine, Philadelphia, PA, USA; Sol Sherry Thrombosis Research Center and Temple University School of Medicine, Philadelphia, PA, USA
| | - Rachit Badolia
- Department of Physiology, Temple University School of Medicine, Philadelphia, PA, USA; Sol Sherry Thrombosis Research Center and Temple University School of Medicine, Philadelphia, PA, USA
| | - Carol A Dangelmaier
- Department of Physiology, Temple University School of Medicine, Philadelphia, PA, USA; Sol Sherry Thrombosis Research Center and Temple University School of Medicine, Philadelphia, PA, USA
| | - Satya P Kunapuli
- Department of Physiology, Temple University School of Medicine, Philadelphia, PA, USA; Sol Sherry Thrombosis Research Center and Temple University School of Medicine, Philadelphia, PA, USA.
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Nagae M, Morita-Matsumoto K, Kato M, Kaneko MK, Kato Y, Yamaguchi Y. A platform of C-type lectin-like receptor CLEC-2 for binding O-glycosylated podoplanin and nonglycosylated rhodocytin. Structure 2014; 22:1711-1721. [PMID: 25458834 DOI: 10.1016/j.str.2014.09.009] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 09/13/2014] [Accepted: 09/17/2014] [Indexed: 11/18/2022]
Abstract
Podoplanin is a transmembrane O-glycoprotein that binds to C-type lectin-like receptor 2 (CLEC-2). The O-glycan-dependent interaction seems to play crucial roles in various biological processes, such as platelet aggregation. Rhodocytin, a snake venom, also binds to CLEC-2 and aggregates platelets in a glycan-independent manner. To elucidate the structural basis of the glycan-dependent and independent interactions, we performed comparative crystallographic studies of podoplanin and rhodocytin in complex with CLEC-2. Both podoplanin and rhodocytin bind to the noncanonical "side" face of CLEC-2. There is a common interaction mode between consecutive acidic residues on the ligands and the same arginine residues on CLEC-2. Other interactions are ligand-specific. Carboxyl groups from the sialic acid residue on podoplanin and from the C terminus of the rhodocytin α subunit interact differently at this "second" binding site on CLEC-2. The unique and versatile binding modes open a way to understand the functional consequences of CLEC-2-ligand interactions.
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Affiliation(s)
- Masamichi Nagae
- Structural Glycobiology Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, RIKEN Global Research Cluster, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Kana Morita-Matsumoto
- Structural Glycobiology Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, RIKEN Global Research Cluster, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Masaki Kato
- Structural Glycobiology Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, RIKEN Global Research Cluster, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Mika Kato Kaneko
- Department of Regional Innovation, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Yukinari Kato
- Department of Regional Innovation, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Yoshiki Yamaguchi
- Structural Glycobiology Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, RIKEN Global Research Cluster, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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The snake venom rhodocytin from Calloselasma rhodostoma- a clinically important toxin and a useful experimental tool for studies of C-type lectin-like receptor 2 (CLEC-2). Toxins (Basel) 2013; 5:665-74. [PMID: 23594438 PMCID: PMC3705285 DOI: 10.3390/toxins5040665] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 04/01/2013] [Accepted: 04/07/2013] [Indexed: 12/21/2022] Open
Abstract
The snake venom, rhodocytin, from the Malayan viper, Calloselasma rhodostoma, and the endogenous podoplanin are identified as ligands for the C-type lectin-like receptor 2 (CLEC-2). The snakebites caused by Calloselasma rhodostoma cause a local reaction with swelling, bleeding and eventually necrosis, together with a systemic effect on blood coagulation with distant bleedings that can occur in many different organs. This clinical picture suggests that toxins in the venom have effects on endothelial cells and vessel permeability, extravasation and, possibly, activation of immunocompetent cells, as well as effects on platelets and the coagulation cascade. Based on the available biological studies, it seems likely that ligation of CLEC-2 contributes to local extravasation, inflammation and, possibly, local necrosis, due to microthrombi and ischemia, whereas other toxins may be more important for the distant hemorrhagic complications. However, the venom contains several toxins and both local, as well as distant, symptoms are probably complex reactions that cannot be explained by the effects of rhodocytin and CLEC-2 alone. The in vivo reactions to rhodocytin are thus examples of toxin-induced crosstalk between coagulation (platelets), endothelium and inflammation (immunocompetent cells). Very few studies have addressed this crosstalk as a part of the pathogenesis behind local and systemic reactions to Calloselasma rhodostoma bites. The author suggests that detailed biological studies based on an up-to-date methodology of local and systemic reactions to Calloselasma rhodostoma bites should be used as a hypothesis-generating basis for future functional studies of the CLEC-2 receptor. It will not be possible to study the effects of purified toxins in humans, but the development of animal models (e.g., cutaneous injections of rhodocytin to mimic snakebites) would supplement studies in humans.
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Manne BK, Getz TM, Hughes CE, Alshehri O, Dangelmaier C, Naik UP, Watson SP, Kunapuli SP. Fucoidan is a novel platelet agonist for the C-type lectin-like receptor 2 (CLEC-2). J Biol Chem 2013; 288:7717-7726. [PMID: 23341451 DOI: 10.1074/jbc.m112.424473] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fucoidan, a sulfated polysaccharide from Fucus vesiculosus, decreases bleeding time and clotting time in hemophilia, possibly through inhibition of tissue factor pathway inhibitor. However, its effect on platelets and the receptor by which fucoidan induces cellular processes has not been elucidated. In this study, we demonstrate that fucoidan induces platelet activation in a concentration-dependent manner. Fucoidan-induced platelet activation was completely abolished by the pan-Src family kinase (SFK) inhibitor, PP2, or when Syk is inhibited. PP2 abolished phosphorylations of Syk and Phospholipase C-γ2. Fucoidan-induced platelet activation had a lag phase, which is reminiscent of platelet activation by collagen and CLEC-2 receptor agonists. Platelet activation by fucoidan was only slightly inhibited in FcRγ-chain null mice, indicating that fucoidan was not acting primarily through GPVI receptor. On the other hand, fucoidan-induced platelet activation was inhibited in platelet-specific CLEC-2 knock-out murine platelets revealing CLEC-2 as a physiological target of fucoidan. Thus, our data show fucoidan as a novel CLEC-2 receptor agonist that activates platelets through a SFK-dependent signaling pathway. Furthermore, the efficacy of fucoidan in hemophilia raises the possibility that decreased bleeding times could be achieved through activation of platelets.
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Affiliation(s)
- Bhanu Kanth Manne
- Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140; Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Todd M Getz
- Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140; Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Craig E Hughes
- Centre for Cardiovascular Sciences, Institute for Biomedical Research, The College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Osama Alshehri
- Centre for Cardiovascular Sciences, Institute for Biomedical Research, The College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Carol Dangelmaier
- Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140; Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Ulhas P Naik
- Cardiovascular Research Institute, University of Delaware, Newark, Delaware 19716
| | - Steve P Watson
- Centre for Cardiovascular Sciences, Institute for Biomedical Research, The College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Satya P Kunapuli
- Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140; Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140; Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140.
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25
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Monoclonal antibodies reveal the alteration of the rhodocetin structure upon α2β1 integrin binding. Biochem J 2011; 440:1-11. [DOI: 10.1042/bj20110584] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The α2β1 antagonist rhodocetin from Calloselasma rhodostoma is a heterotetrameric CLRP (C-type lectin-related protein) consisting of four distinct chains, α, β, γ and δ. Via their characteristic domain-swapping loops, the individual chains form two subunits, αβ and γδ. To distinguish the four chains which share similar molecular masses and high sequence homologies, we generated 11 mAbs (monoclonal antibodies) with different epitope specificities. Four groups of distinct mAbs were generated: the first targeted the rhodocetin β chain, the second group bound to the αβ subunit mostly in a conformation-dependent manner, the third group recognized the γδ subunit only when separated from the αβ subunit, whereas a fourth group interacted with the γδ subunit both in the heterotetrameric molecule and complexed with the integrin α2 A-domain. Using the specific mAbs, we have shown that the rhodocetin heterotetramer dissociates into the αβ and γδ subunit upon binding to the integrin α2 A-domain at both the molecular and cellular levels. After dissociation, the γδ subunit firmly interacts with the α2β1 integrin, thereby blocking it, whereas the rhodocetin αβ subunit is released from the complex. The small molecular interface between the αβ and γδ subunits within rhodocetin is mostly mediated by charged residues, which causes the two dissociated subunits to have hydrophilic surfaces.
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26
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Ozbek S. The cnidarian nematocyst: a miniature extracellular matrix within a secretory vesicle. PROTOPLASMA 2011; 248:635-640. [PMID: 20957500 DOI: 10.1007/s00709-010-0219-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 10/05/2010] [Indexed: 05/30/2023]
Abstract
Nematocysts are the taxon-defining features of all cnidarians including jellyfish, sea anemones, and corals. They are highly sophisticated organelles used for the capture of prey and defense. The nematocyst capsule is produced within a giant post-Golgi vesicle, which is continuously fed by proteins from the secretory pathway. Mature nematocysts consist of a hollow capsule body in which a long tubule is coiled up that, upon discharge, is expelled in a harpoon-like fashion. This is accompanied by the release of a toxin cocktail stored in the capsule matrix. Nematocyst discharge, which is one of the fastest processes in biology, is driven by an extreme osmotic pressure of about 150 bar. The molecular analysis of the nematocyst has from the beginning indicated a collagenous nature of the capsule structure. In particular, a large family of unusual minicollagens has been demonstrated to form the highly resistant scaffold of the capsule. Recent findings on the molecular composition of Hydra nematocysts have confirmed the notion of a specialized extracellular matrix, which is assembled during an intracellular secretion process to form the most complex predatory apparatus at the cellular level.
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Affiliation(s)
- Suat Ozbek
- Institute of Zoology, Department of Molecular Evolution and Genomics, University of Heidelberg, Im Neuenheimer Feld 230, 69120, Heidelberg, Germany.
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27
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Watson AA, O’Callaghan CA. Molecular analysis of the interaction of the snake venom rhodocytin with the platelet receptor CLEC-2. Toxins (Basel) 2011; 3:991-1003. [PMID: 22069753 PMCID: PMC3202865 DOI: 10.3390/toxins3080991] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 07/21/2011] [Accepted: 08/08/2011] [Indexed: 01/27/2023] Open
Abstract
The Malayan pit viper, Calloselasma rhodostoma, produces a potent venom toxin, rhodocytin (aggretin) which causes platelet aggregation. Rhodocytin is a ligand for the receptor CLEC-2 on the surface of platelets. The interaction of these two molecules initiates a signaling pathway which results in platelet activation and aggregation. We have previously solved the crystal structures of CLEC-2 and of rhodocytin, and have proposed models by which tetrameric rhodocytin may interact with either two monomers of CLEC-2, or with one or two copies of dimeric CLEC-2. In the current study we use a range of approaches to analyze the molecular interfaces and dynamics involved in the models of the interaction of rhodocytin with either one or two copies of dimeric CLEC-2, and their implications for clustering of CLEC-2 on the platelet surface.
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Affiliation(s)
- Aleksandra A. Watson
- Department of Biochemistry, University of Cambridge/ 80 Tennis Court Road, Cambridge, CB2 1GA, UK;
| | - Christopher A. O’Callaghan
- Henry Wellcome Building for Molecular Physiology, University of Oxford/ Roosevelt Drive, Oxford, OX3 7BN, UK
- Author to whom correspondence should be addressed; ; Tel.: +44-1865-287789; Fax: +44-1865-287787
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28
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Suzuki-Inoue K, Inoue O, Ozaki Y. Novel platelet activation receptor CLEC-2: from discovery to prospects. J Thromb Haemost 2011; 9 Suppl 1:44-55. [PMID: 21781241 DOI: 10.1111/j.1538-7836.2011.04335.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
C-type lectin-like receptor 2 (CLEC-2) has been identified as a receptor for the platelet activating snake venom rhodocytin. CLEC-2 elicits powerful platelet activation signals in conjunction with Src, Syk kinases, and phospholipase Cγ2, similar to the collagen receptor glycoprotein (GP) VI/FcRγ-chain complex. In contrast to GPVI/FcRγ, which initiates platelet activation through the tandem YxxL motif immunoreceptor tyrosine-based activation motif (ITAM), CLEC-2 signals via the single YxxL motif hemi-ITAM. The endogenous ligand of CLEC-2 has been identified as podoplanin, which is expressed on the surface of tumour cells and facilitates tumour metastasis by inducing platelet activation. Studies of CLEC-2-deficient mice have revealed several physiological roles of CLEC-2. Podoplanin is also expressed in lymphatic endothelial cells as well as several other cells, including type I alveolar cells and kidney podocytes, but is absent from vascular endothelial cells. In the developmental stages, when the primary lymph sac is derived from the cardinal vein, podoplanin activates platelets in lymphatic endothelial cells by binding to CLEC-2, which facilitates blood/lymphatic vessel separation. Moreover, CLEC-2 is involved in thrombus stabilisation under flow conditions in part through homophilic interactions. However, the absence of CLEC-2 does not significantly increase bleeding tendency. CLEC-2 may be a good target protein for novel anti-platelet drugs or anti-metastatic drugs having therapeutic and preventive effects on arterial thrombosis and cancer, the primary causes of mortality in developed countries. In this article, we review the mechanisms of signal transduction, structure, expression, and function of CLEC-2.
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Affiliation(s)
- K Suzuki-Inoue
- Department of Clinical and Laboratory Medicine, Faculty of Medicine, University of Yamanashi, Chuo, Yamanashi, Japan
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29
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Clemetson KJ. Snaclecs (snake C-type lectins) that inhibit or activate platelets by binding to receptors. Toxicon 2010; 56:1236-46. [DOI: 10.1016/j.toxicon.2010.03.011] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Accepted: 03/15/2010] [Indexed: 11/25/2022]
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Séverin S, Pollitt AY, Navarro-Nuñez L, Nash CA, Mourão-Sá D, Eble JA, Senis YA, Watson SP. Syk-dependent phosphorylation of CLEC-2: a novel mechanism of hem-immunoreceptor tyrosine-based activation motif signaling. J Biol Chem 2010; 286:4107-16. [PMID: 21098033 PMCID: PMC3039337 DOI: 10.1074/jbc.m110.167502] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The C-type lectin-like receptor CLEC-2 signals via phosphorylation of a single cytoplasmic YXXL sequence known as a hem-immunoreceptor tyrosine-based activation motif (hemITAM). In this study, we show that phosphorylation of CLEC-2 by the snake toxin rhodocytin is abolished in the absence of the tyrosine kinase Syk but is not altered in the absence of the major platelet Src family kinases, Fyn, Lyn, and Src, or the tyrosine phosphatase CD148, which regulates the basal activity of Src family kinases. Further, phosphorylation of CLEC-2 by rhodocytin is not altered in the presence of the Src family kinase inhibitor PP2, even though PLCγ2 phosphorylation and platelet activation are abolished. A similar dependence of phosphorylation of CLEC-2 on Syk is also seen in response to stimulation by an IgG mAb to CLEC-2, although interestingly CLEC-2 phosphorylation is also reduced in the absence of Lyn. These results provide the first definitive evidence that Syk mediates phosphorylation of the CLEC-2 hemITAM receptor with Src family kinases playing a critical role further downstream through the regulation of Syk and other effector proteins, providing a new paradigm in signaling by YXXL-containing receptors.
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Affiliation(s)
- Sonia Séverin
- Centre for Cardiovascular Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
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Abstract
The C-type lectin receptor CLEC-2 activates platelets through Src and Syk tyrosine kinases, leading to tyrosine phosphorylation of downstream adapter proteins and effector enzymes, including phospholipase-C gamma2. Signaling is initiated through phosphorylation of a single conserved tyrosine located in a YxxL sequence in the CLEC-2 cytosolic tail. The signaling pathway used by CLEC-2 shares many similarities with that used by receptors that have 1 or more copies of an immunoreceptor tyrosine-based activation motif, defined by the sequence Yxx(L/I)x(6-12)Yxx(L/I), in their cytosolic tails or associated receptor chains. Phosphorylation of the conserved immunoreceptor tyrosine-based activation motif tyrosines promotes Syk binding and activation through binding of the Syk tandem SH2 domains. In this report, we present evidence using peptide pull-down studies, surface plasmon resonance, quantitative Western blotting, tryptophan fluorescence measurements, and competition experiments that Syk activation by CLEC-2 is mediated by the cross-linking through the tandem SH2 domains with a stoichiometry of 2:1. In support of this model, cross-linking and electron microscopy demonstrate that CLEC-2 is present as a dimer in resting platelets and converted to larger complexes on activation. This is a unique mode of activation of Syk by a single YxxL-containing receptor.
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Phosphorylation of CLEC-2 is dependent on lipid rafts, actin polymerization, secondary mediators, and Rac. Blood 2010; 115:2938-46. [PMID: 20154214 DOI: 10.1182/blood-2009-12-257212] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The C-type lectin-like receptor 2 (CLEC-2) activates platelets through Src and Syk tyrosine kinases via a single cytoplasmic YxxL motif known as a hem immunoreceptor tyrosine-based activation motif (hemITAM). Here, we demonstrate using sucrose gradient ultracentrifugation and methyl-beta-cyclodextrin treatment that CLEC-2 translocates to lipid rafts upon ligand engagement and that translocation is essential for hemITAM phosphorylation and signal initiation. HemITAM phosphorylation, but not translocation, is also critically dependent on actin polymerization, Rac1 activation, and release of ADP and thromboxane A(2) (TxA(2)). The role of ADP and TxA(2) in mediating phosphorylation is dependent on ligand engagement and rac activation but is independent of platelet aggregation. In contrast, tyrosine phosphorylation of the GPVI-FcRgamma-chain ITAM, which has 2 YxxL motifs, is independent of actin polymerization and secondary mediators. These results reveal a unique series of proximal events in CLEC-2 phosphorylation involving actin polymerization, secondary mediators, and Rac activation.
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Watson AA, Christou CM, James JR, Fenton-May AE, Moncayo GE, Mistry AR, Davis SJ, Gilbert RJC, Chakera A, O'Callaghan CA. The platelet receptor CLEC-2 is active as a dimer. Biochemistry 2009; 48:10988-96. [PMID: 19824697 DOI: 10.1021/bi901427d] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The platelet receptor CLEC-2 binds to the snake venom toxin rhodocytin and the tumor cell surface protein podoplanin. Binding of either of these ligands promotes phosphorylation of a single tyrosine residue in the YXXL motif in the intracellular domain of CLEC-2. Phosphorylation of this tyrosine initiates binding of spleen tyrosine kinase (Syk) and triggers further downstream signaling events and ultimately potent platelet activation and aggregation. However, it is unclear how a single YXXL motif can interact efficiently with Syk, which usually recognizes two tandem YXXL repeats presented as an immunoreceptor tyrosine-based activation motif (ITAM). Using bioluminescence resonance energy transfer, coimmunopreciptitation, recombinant protein expression and analytical gel filtration chromatography, surface plasmon resonance, Western blotting, multiangle light scattering (MALS), and analytical ultracentrifugation, we show that CLEC-2 exists as a non-disulfide-linked homodimer which could allow each Syk molecule to interact with two YXXL motifs, one from each CLEC-2 monomer.
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Affiliation(s)
- Aleksandra A Watson
- Henry Wellcome Building for Molecular Physiology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
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Spalton JC, Mori J, Pollitt AY, Hughes CE, Eble JA, Watson SP. The novel Syk inhibitor R406 reveals mechanistic differences in the initiation of GPVI and CLEC-2 signaling in platelets. J Thromb Haemost 2009; 7:1192-9. [PMID: 19422460 DOI: 10.1111/j.1538-7836.2009.03451.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND Syk is a key mediator of signaling pathways downstream of several platelet surface receptors including GPVI/FcRgamma collagen receptor, the C-type lectin receptor CLEC-2, and integrin alphaIIbbeta3. A recent study identified the novel small molecule R406 as a selective inhibitor of Syk. OBJECTIVES The present study evaluates the role of Syk in human platelets using the novel inhibitor R406. METHODS Agonist-induced GPVI and CLEC-2 signaling were assessed using aggregometry, immunoprecipitation and western blotting to determine the effects of R406 on platelet activation. RESULTS We demonstrate R406 to be a powerful inhibitor of Syk in human platelets. R406 abrogated shape change and aggregation induced by activation of GPVI and CLEC-2, and reduced platelet spreading on fibrinogen. The inhibitory effect of R406 was associated with inhibition of tyrosine phosphorylation of signaling proteins that lay downstream of Syk for all three receptors, including PLCgamma2. Strikingly, R406 markedly inhibited tyrosine phosphorylation of CLEC-2 and Syk downstream of CLEC-2 activation, whereas phosphorylation of Syk downstream of GPVI and integrin alphaIIbbeta3 was unaffected. CONCLUSIONS The inhibitory effect of R406 provides direct evidence of a role for Syk in GPVI, CLEC-2 and integrin alphaIIbbeta3 signaling in human platelets. Further, the results demonstrate a critical role for Syk in mediating tyrosine phosphorylation of CLEC-2, suggesting a novel model in which both Src and Syk kinases regulate tyrosine phosphorylation of the C-type lectin receptor leading to platelet activation.
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Affiliation(s)
- J C Spalton
- Centre for Cardiovascular Sciences, Institute for Biomedical Research, The College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
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35
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O’Callaghan CA. Thrombomodulation via CLEC-2 targeting. Curr Opin Pharmacol 2009; 9:90-5. [DOI: 10.1016/j.coph.2008.11.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Accepted: 11/03/2008] [Indexed: 12/22/2022]
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36
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Huysamen C, Brown GD. The fungal pattern recognition receptor, Dectin-1, and the associated cluster of C-type lectin-like receptors. FEMS Microbiol Lett 2008; 290:121-8. [PMID: 19025564 PMCID: PMC2704933 DOI: 10.1111/j.1574-6968.2008.01418.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The mammalian natural killer gene complex (NKC) contains several families of type II transmembrane C-type lectin-like receptors (CLRs) that are best known for their involvement in the detection of virally infected or transformed cells, through the recognition of endogenous (or self) proteinacious ligands. However, certain CLR families within the NKC, particularly those expressed by myeloid cells, recognize structurally diverse ligands and perform a variety of other immune and homoeostatic functions. One such family is the 'Dectin-1 cluster' of CLRs, which includes MICL, CLEC-2, CLEC12B, CLEC9A, CLEC-1, Dectin-1 and LOX-1. Here, we review each of these CLRs, exploring our current understanding of their ligands and functions and highlighting where they have provided new insights into the underlying mechanisms of immunity and homeostasis.
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Affiliation(s)
- Cristal Huysamen
- Clinical Laboratory Sciences, Division of Immunology, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
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