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Kasirer-Friede A, Peuhu E, Ivaska J, Shattil SJ. Platelet SHARPIN regulates platelet adhesion and inflammatory responses through associations with αIIbβ3 and LUBAC. Blood Adv 2022; 6:2595-2607. [PMID: 34991155 PMCID: PMC9043921 DOI: 10.1182/bloodadvances.2021005611] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 12/20/2021] [Indexed: 11/20/2022] Open
Abstract
Platelets form hemostatic plugs to prevent blood loss, and they modulate immunity and inflammation in several ways. A key event during hemostasis is activation of integrin αIIbβ3 through direct interactions of the β3 cytoplasmic tail with talin and kindlin-3. Recently, we showed that human platelets express the adapter molecule Shank-associated RH domain interacting protein (SHARPIN), which can associate directly with the αIIb cytoplasmic tail and separately promote NF-κB pathway activation as a member of the Met-1 linear ubiquitination activation complex (LUBAC). Here we investigated the role of SHARPIN in platelets after crossing Sharpin flox/flox (fl/fl) mice with PF4-Cre or GPIbα-Cre mice to selectively delete SHARPIN in platelets. SHARPIN-null platelets adhered to immobilized fibrinogen through αIIbβ3, and they spread more extensively than littermate control platelets in a manner dependent on feedback stimulation by platelet adenosine diphosphate (ADP) (P < .01). SHARPIN-null platelets showed increased colocalization of αIIbβ3 with talin as assessed by super-resolution microscopy and increased binding of soluble fibrinogen in response to submaximal concentrations of ADP (P < .05). However, mice with SHARPIN-null platelets showed compromised thrombus growth on collagen and slightly prolonged tail bleeding times. Platelets lacking SHARPIN also showed reduced NF-κB activation and linear ubiquitination of protein substrates upon challenge with classic platelet agonists. Furthermore, the loss of platelet SHARPIN resulted in significant reduction in inflammation in murine models of colitis and peritonitis (P < .01). Thus, SHARPIN plays differential and context-dependent roles in platelets to regulate important inflammatory and integrin adhesive functions of these anucleate cells.
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Affiliation(s)
- Ana Kasirer-Friede
- Division of Hematology-Oncology, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Emilia Peuhu
- Institute of Biomedicine, Cancer Research Laboratory FICAN West, University of Turku, Turku, Finland
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland; and
| | - Johanna Ivaska
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland; and
- Department of Biochemistry, University of Turku, Turku, Finland
| | - Sanford J Shattil
- Division of Hematology-Oncology, Department of Medicine, University of California, San Diego, La Jolla, CA
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2
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Martins Lima A, Saint Auguste DS, Cuenot F, Martins Cavaco AC, Lachkar T, Khawand CME, Fraga-Silva RA, Stergiopulos N. Standardization and Validation of Fluorescence-Based Quantitative Assay to Study Human Platelet Adhesion to Extracellular-Matrix in a 384-Well Plate. Int J Mol Sci 2020; 21:ijms21186539. [PMID: 32906775 PMCID: PMC7554887 DOI: 10.3390/ijms21186539] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 08/31/2020] [Accepted: 09/03/2020] [Indexed: 11/17/2022] Open
Abstract
Platelets play a crucial role in the immunological response and are involved in the pathological settings of vascular diseases, and their adhesion to the extracellular matrix is important to bring leukocytes close to the endothelial cells and to form and stabilize the thrombus. Currently there are several methods to study platelet adhesion; however, the optimal parameters to perform the assay vary among studies, which hinders their comparison and reproducibility. Here, a standardization and validation of a fluorescence-based quantitative adhesion assay to study platelet-ECM interaction in a high-throughput screening format is proposed. Our study confirms that fluorescence-based quantitative assays can be effectively used to detect platelet adhesion, in which BCECF-AM presents the highest sensitivity in comparison to other dyes.
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Affiliation(s)
- Augusto Martins Lima
- Laboratory of Hemodynamics and Cardiovascular Technology (LHTC), Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; (D.S.S.A.); (F.C.); (T.L.); (C.M.E.K.); (R.A.F.-S.); (N.S.)
- Institute of Bioengineering, École Polytechnique Fédérale de Lausanne Station 09, MED 3.2924, CH-1015 Lausanne, Switzerland
- Correspondence:
| | - Damian S. Saint Auguste
- Laboratory of Hemodynamics and Cardiovascular Technology (LHTC), Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; (D.S.S.A.); (F.C.); (T.L.); (C.M.E.K.); (R.A.F.-S.); (N.S.)
- Laboratory for Orthopaedic Technology, Institute for Biomechanics, Swiss Federal Institute of Technology Zurich, 8093 Zurich, Switzerland
| | - François Cuenot
- Laboratory of Hemodynamics and Cardiovascular Technology (LHTC), Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; (D.S.S.A.); (F.C.); (T.L.); (C.M.E.K.); (R.A.F.-S.); (N.S.)
| | - Ana C. Martins Cavaco
- Luis Costa Lab, Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, 1649-028 Lisboa, Portugal;
| | - Tom Lachkar
- Laboratory of Hemodynamics and Cardiovascular Technology (LHTC), Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; (D.S.S.A.); (F.C.); (T.L.); (C.M.E.K.); (R.A.F.-S.); (N.S.)
| | - Cindy Marie Elodie Khawand
- Laboratory of Hemodynamics and Cardiovascular Technology (LHTC), Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; (D.S.S.A.); (F.C.); (T.L.); (C.M.E.K.); (R.A.F.-S.); (N.S.)
| | - Rodrigo A. Fraga-Silva
- Laboratory of Hemodynamics and Cardiovascular Technology (LHTC), Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; (D.S.S.A.); (F.C.); (T.L.); (C.M.E.K.); (R.A.F.-S.); (N.S.)
| | - Nikolaos Stergiopulos
- Laboratory of Hemodynamics and Cardiovascular Technology (LHTC), Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; (D.S.S.A.); (F.C.); (T.L.); (C.M.E.K.); (R.A.F.-S.); (N.S.)
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3
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Zarka R, Horev MB, Volberg T, Neubauer S, Kessler H, Spatz JP, Geiger B. Differential Modulation of Platelet Adhesion and Spreading by Adhesive Ligand Density. NANO LETTERS 2019; 19:1418-1427. [PMID: 30649888 PMCID: PMC6437653 DOI: 10.1021/acs.nanolett.8b03513] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 01/08/2019] [Indexed: 05/25/2023]
Abstract
Platelets play a major role in hemostasis and thrombosis, by binding to the underlying extracellular matrix around injured blood vessels, via integrin receptors. In this study, we investigated the effects of adhesive ligand spacing on the stability of platelets' adhesion and the mode of their spreading on extracellular surfaces. Toward this end, we have examined the differential adhesion and spreading of human platelets onto nanogold-patterned surfaces, functionalized with the αIIbβ3 integrin ligand, SN528. Combining light- and scanning electron-microscopy, we found that interaction of platelets with surfaces coated with SN528 at spacing of 30-60 nm induces the extension of filopodia through which the platelets stably attach to the nanopatterned surface and spread on it. Increasing the nanopattern-gold spacing to 80-100 nm resulted in a dramatic reduction (>95%) in the number of adhering platelets. Surprisingly, a further increase in ligand spacing to 120 nm resulted in platelet binding to the surface at substantially larger numbers, yet these platelets remained discoid and were essentially devoid of filopodia and lamellipodia. These results indicate that the stimulation of filopodia extension by adhering platelets, and the consequent spreading on these surfaces depend on different ligand densities. Thus, the extension of filopodia occurs on surfaces with a ligand spacing of 100 nm or less, while the sustainability and growth of these initial adhesions and induction of extensive platelet adhesion and spreading requires lower ligand-to-ligand spacing (≤60 nm). The mechanisms underlying this differential ligand-density sensing by platelets, as well as the unexpected retention of discoid platelets on surfaces with even larger spacing (120 nm) are discussed.
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Affiliation(s)
- Revital Zarka
- Department
of Molecular Cell Biology, The Weizmann
Institute of Science, Rehovot 76100, Israel
| | - Melanie B. Horev
- Department
of Molecular Cell Biology, The Weizmann
Institute of Science, Rehovot 76100, Israel
| | - Tova Volberg
- Department
of Molecular Cell Biology, The Weizmann
Institute of Science, Rehovot 76100, Israel
| | - Stefanie Neubauer
- Institute
for Advanced Study (IAS) and Center of Integrated Protein Science,
Department of Chemistry, Technical University
of Munich, 85747 Garching, Germany
| | - Horst Kessler
- Institute
for Advanced Study (IAS) and Center of Integrated Protein Science,
Department of Chemistry, Technical University
of Munich, 85747 Garching, Germany
| | - Joachim P. Spatz
- Department
of Cellular Biophysics, Max Planck Institute
for Medical Research, Jahnstrasse 29, D-69120 Heidelberg, Germany
| | - Benjamin Geiger
- Department
of Molecular Cell Biology, The Weizmann
Institute of Science, Rehovot 76100, Israel
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4
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SHARPIN at the nexus of integrin, immune, and inflammatory signaling in human platelets. Proc Natl Acad Sci U S A 2019; 116:4983-4988. [PMID: 30804189 DOI: 10.1073/pnas.1819156116] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Platelets mediate primary hemostasis, and recent work has emphasized platelet participation in immunity and inflammation. The function of the platelet-specific integrin αIIbβ3 as a fibrinogen receptor in hemostasis is well defined, but the roles of αIIbβ3 or integrin-associated proteins in nonhemostatic platelet functions are poorly understood. Here we show that human platelets express the integrin-associated protein SHARPIN with functional consequences. In leukocytes, SHARPIN interacts with integrin α cytoplasmic tails, and it is also an obligate member of the linear ubiquitin chain assembly complex (LUBAC), which mediates Met1 linear ubiquitination of proteins leading to canonical NF-κB activation. SHARPIN interacted with αIIb in pull-down and coimmunoprecipitation assays. SHARPIN was partially localized, as was αIIbβ3, at platelet edges, and thrombin stimulation induced more central SHARPIN localization. SHARPIN also coimmunoprecipitated from platelets with the two other proteins comprising LUBAC, the E3 ligase HOIP and HOIL-1. Platelet stimulation with thrombin or inflammatory agonists, including lipopolysaccharide or soluble CD40 ligand (sCD40L), induced Met1 linear ubiquitination of the NF-κB pathway protein NEMO and serine-536 phosphorylation of the p65 RelA subunit of NF-κB. In human megakaryocytes and/or platelets derived from induced pluripotent stem (iPS) cells, SHARPIN knockdown caused increased basal and agonist-induced fibrinogen binding to αIIbβ3 as well as reduced Met1 ubiquitination and RelA phosphorylation. Moreover, these SHARPIN knockdown cells exhibited increased surface expression of MHC class I molecules and increased release of sCD40L. These results establish that SHARPIN functions in the human megakaryocyte/platelet lineage through protein interactions at the nexus of integrin and immune/inflammatory signaling.
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5
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Profilin 1-mediated cytoskeletal rearrangements regulate integrin function in mouse platelets. Blood Adv 2019; 2:1040-1045. [PMID: 29739775 DOI: 10.1182/bloodadvances.2017014001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 04/14/2018] [Indexed: 11/20/2022] Open
Abstract
Key Points
Profilin 1–mediated cytoskeletal dynamics regulate platelet β1- and β3-integrin function and turnover. Profilin 1 deficiency in platelets impairs hemostasis and results in a marked protection from arterial thrombosis.
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7
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Paknikar AK, Eltzner B, Köster S. Direct characterization of cytoskeletal reorganization during blood platelet spreading. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 144:166-176. [PMID: 29843920 DOI: 10.1016/j.pbiomolbio.2018.05.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/15/2018] [Accepted: 05/04/2018] [Indexed: 11/18/2022]
Abstract
Blood platelets are the key cellular players in blood clotting and thus of great biomedical importance. While spreading at the site of injury, they reorganize their cytoskeleton within minutes and assume a flat appearance. As platelets possess no nucleus, many standard methods for visualizing cytoskeletal components by means of fluorescence tags fail. Here we employ silicon-rhodamine actin and tubulin probes for imaging these important proteins in a time-resolved manner. We find two distinct timescales for platelet spread area development and for cytoskeletal reorganization, indicating that although cell spreading is most likely associated with actin polymerization at the cell edges, distinct, stress-fiber-like actin structures within the cell, which may be involved in the generation of contractile forces, form on their own timescale. Following microtubule dynamics allows us to distinguish the role of myosin, microtubules and actin during early spreading.
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Affiliation(s)
- Aishwarya K Paknikar
- Institute for X-Ray Physics, University of Goettingen, Göttingen, 37077, Germany
| | - Benjamin Eltzner
- Institute for Mathematical Stochastics, University of Goettingen, Göttingen, 37077, Germany
| | - Sarah Köster
- Institute for X-Ray Physics, University of Goettingen, Göttingen, 37077, Germany; DZHK (German Center for Cardiovascular Research), partner site Göttingen, Germany.
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8
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Abstract
PURPOSE OF REVIEW Although platelet endocytosis has been recognized in granule cargo loading and the trafficking of several platelet surface receptors, its acute physiological relevance is poorly understood as is its mechanism. The present review discusses the current understanding of platelet endocytosis and its implications for platelet function. RECENT FINDINGS Recent studies are beginning to identify and define the proteins that mediate platelet endocytosis. These studies have shown that platelets contain different endosomal compartments and may use multiple endocytic routes to take in circulating molecules and surface proteins. The studies have also shown that platelet endocytosis is involved in several aspects of platelet function such as signaling, spreading, and granule cargo loading. SUMMARY Mechanistic studies of platelet endocytosis have shown it to be not only involved in granule cargo loading but also in various other platelet functions important for hemostasis and beyond.
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9
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Egot M, Kauskot A, Lasne D, Gaussem P, Bachelot-Loza C. Biphasic myosin II light chain activation during clot retraction. Thromb Haemost 2017; 110:1215-22. [DOI: 10.1160/th13-04-0335] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 08/05/2013] [Indexed: 12/13/2022]
Abstract
SummaryClot retraction is an essential step during primary haemostasis, thereby promoting thrombus stability and wound healing. Integrin αIIbβ3 plays a critical role in clot retraction, by inducing acto-myosin interactions that allow platelet cytoskeleton reorganisation. However, the signalling pathways that lead to clot retraction are still misunderstood. In this study, we report the first data on the kinetics of myosin II light chain (MLC) phosphorylation during clot retraction. We found an early phosphorylation peak followed by a second peak. By using specific inhibitors of kinases and small G proteins, we showed that MLC kinase (MLCK), RhoA/ROCK, and Rac-1 were involved in clot retraction and in the early MLC phosphorylation peak. Only Rac-1 and actin polymerisation, controlled by outside-in signalling, were crucial to the second MLC phosphorylation peak.
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10
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Lu DH, Hsu CC, Huang SW, Tu HJ, Huang TF, Liou HC, Liao HM, Chen CH, Fu WM, Gau SSF. ARHGEF10 knockout inhibits platelet aggregation and protects mice from thrombus formation. J Thromb Haemost 2017; 15:2053-2064. [PMID: 28799234 DOI: 10.1111/jth.13799] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Indexed: 11/28/2022]
Abstract
Essentials ARHGEF10 single-nucleotide polymorphism provides risk of ischemic and atherothrombotic stroke. The role of ARHGEF10 in platelet function was examined using ARHGEF10 knockout mice. ARHGEF10 deficiency inhibits platelet function and arterial thrombus formation. ARHGEF10 knockout protects mice from stroke-induced infarction. SUMMARY Background ARHGEF10, a member of the Rho guanine nucleotide exchange factor (GEF) family, stimulates Rho GTPases. Rho GTPases have been reported to regulate a variety of cellular behaviors, such as cell polarity, cytoskeletal organization, and gene transcription. ARHGEF10 single-nucleotide polymorphisms are linked to the risk of ischemic stroke. However, the role of ARHGEF10 in platelet function remains unknown. Objective To examine the role of ARHGEF10 in platelet function. Methods ARHGEF10-/- were generated. We examined the in vitro and in vivo effects of ARHGEF10 knockout on platelet function and arterial thrombosis formation. Results ARHGEF10-/- mice had normal platelet counts, but showed altered aggregation in response to thrombin, collagen, ADP, protease-activated receptor-4 peptide, and U46619 stimulation. ARHGEF10 knockout influenced platelet spreading on fibrinogen-coated surfaces, and caused the platelets to show less lamellipodia-like extension than wild-type platelets. ARHGEF10 knockout also inhibited platelet clot retraction induced by thrombin stimulation. ARHGEF10 knockout resulted in prolonged tail bleeding time and inhibited the stable thrombus formation induced by FeCl3 in the carotid artery. Conclusions ARHGEF10 serves as an important regulator in platelet shape change, spreading, and aggregation. Moreover, ARHGEF10 also plays an important role in arterial thrombosis formation.
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Affiliation(s)
- D-H Lu
- Pharmacological Institute, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - C-C Hsu
- Pharmacological Institute, College of Medicine, National Taiwan University, Taipei, Taiwan
- Department of Botanicals, Medical and Pharmaceutical Industry Technology and Development Center, Taipei, Taiwan
| | - S-W Huang
- Pharmacological Institute, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - H-J Tu
- Pharmacological Institute, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - T-F Huang
- Pharmacological Institute, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - H-C Liou
- Pharmacological Institute, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - H-M Liao
- Department of Psychiatry, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
| | - C-H Chen
- Department of Psychiatry, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
- Department and Graduate Institute of Biomedical Sciences, Chang Gung University, Taipei, Taiwan
| | - W-M Fu
- Pharmacological Institute, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - S S-F Gau
- Department of Psychiatry, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
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11
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Abstract
Integrin αIIbβ3 is a highly abundant heterodimeric platelet receptor that can transmit information bidirectionally across the plasma membrane, and plays a critical role in hemostasis and thrombosis. Upon platelet activation, inside-out signaling pathways increase the affinity of αIIbβ3 for fibrinogen and other ligands. Ligand binding and integrin clustering subsequently stimulate outside-in signaling, which initiates and amplifies a range of cellular events driving essential platelet processes such as spreading, thrombus consolidation, and clot retraction. Integrin αIIbβ3 has served as an excellent model for the study of integrin biology, and it has become clear that integrin outside-in signaling is highly complex and involves a vast array of enzymes, signaling adaptors, and cytoskeletal components. In this review, we provide a concise but comprehensive overview of αIIbβ3 outside-in signaling, focusing on the key players involved, and how they cooperate to orchestrate this critical aspect of platelet biology. We also discuss gaps in the current understanding of αIIbβ3 outside-in signaling and highlight avenues for future investigation.
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12
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Twinfilin 2a regulates platelet reactivity and turnover in mice. Blood 2017; 130:1746-1756. [PMID: 28743718 DOI: 10.1182/blood-2017-02-770768] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 07/21/2017] [Indexed: 01/22/2023] Open
Abstract
Regulated reorganization of the actin cytoskeleton is a prerequisite for proper platelet production and function. Consequently, defects in proteins controlling actin dynamics have been associated with platelet disorders in humans and mice. Twinfilin 2a (Twf2a) is a small actin-binding protein that inhibits actin filament assembly by sequestering actin monomers and capping filament barbed ends. Moreover, Twf2a binds heterodimeric capping proteins, but the role of this interaction in cytoskeletal dynamics has remained elusive. Even though Twf2a has pronounced effects on actin dynamics in vitro, only little is known about its function in vivo. Here, we report that constitutive Twf2a-deficient mice (Twf2a-/-) display mild macrothrombocytopenia due to a markedly accelerated platelet clearance in the spleen. Twf2a-/- platelets showed enhanced integrin activation and α-granule release in response to stimulation of (hem) immunoreceptor tyrosine-based activation motif (ITAM) and G-protein-coupled receptors, increased adhesion and aggregate formation on collagen I under flow, and accelerated clot retraction and spreading on fibrinogen. In vivo, Twf2a deficiency resulted in shortened tail bleeding times and faster occlusive arterial thrombus formation. The hyperreactivity of Twf2a-/- platelets was attributed to enhanced actin dynamics, characterized by an increased activity of n-cofilin and profilin 1, leading to a thickened cortical cytoskeleton and hence sustained integrin activation by limiting calpain-mediated integrin inactivation. In summary, our results reveal the first in vivo functions of mammalian Twf2a and demonstrate that Twf2a-controlled actin rearrangements dampen platelet activation responses in a n-cofilin- and profilin 1-dependent manner, thereby indirectly regulating platelet reactivity and half-life in mice.
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13
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Wang Y, Jiang L, Mo X, Lan Y, Yang X, Liu X, Zhang J, Zhu L, Liu J, Wu X. Megakaryocytic Smad4 Regulates Platelet Function through Syk and ROCK2 Expression. Mol Pharmacol 2017; 92:285-296. [PMID: 28663280 DOI: 10.1124/mol.116.107417] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 06/21/2017] [Indexed: 01/03/2023] Open
Abstract
Smad4, a key transcription factor in the transforming growth factor-β signaling pathway, is involved in a variety of cell physiologic and pathologic processes. Here, we characterized megakaryocyte/platelet-specific Smad4 deficiency in mice to elucidate its effect on platelet function. We found that megakaryocyte/platelet-specific loss of Smad4 caused mild thrombocytopenia and significantly extended first occlusion time and tail bleeding time in mice. Smad4-deficient platelets showed reduced agonist-induced platelet aggregation. Further studies showed that a severe defect was seen in integrin αIIbβ3-mediated bidirectional (inside-out and outside-in) signaling in Smad4-deficient platelets, as evidenced by reduced fibrinogen binding and α-granule secretion, suppressed platelet spreading and clot retraction. Microarray analysis showed that the expression levels of multiple genes were altered in Smad4-deficient platelets. Among these genes, spleen tyrosine kinase (Syk) and Rho-associated coiled-coil containing protein kinase 2 (ROCK2) were downregulated several times as confirmed by quantitative reverse-transcription polymerase chain reaction and immunoblotting. Further research showed that Smad4 directly regulates ROCK2 transcription but indirectly regulates Syk. Megakaryocyte/platelet-specific Smad4 deficiency caused decreased expression levels of Syk and ROCK2 in platelets. These results suggest potential links among Smad4 deficiency, attenuated Syk, and ROCK2 expression and defective platelet activation.
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Affiliation(s)
- Yanhua Wang
- Department of Laboratory Medicine, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, People's Republic of China (Y.W.); Institute for Pediatric Translational Medicine, Shanghai Children's Medical Center, Shanghai, People's Republic of China (L.J., X.M.); State Key Laboratory of Proteomics, Genetic Laboratory of Development and Diseases, Institute of Biotechnology, Beijing, People's Republic of China (Y.L., X.Y.); Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (X.L., J.Z.); Cyrus Tang Hematology Center, Soochow University, Suzhou, People's Republic of China (L.Z.); Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (J.L.); and The Central Laboratory of The Eighth People's Hospital of Shanghai, Shanghai, People's Republic of China (X.W.)
| | - Lirong Jiang
- Department of Laboratory Medicine, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, People's Republic of China (Y.W.); Institute for Pediatric Translational Medicine, Shanghai Children's Medical Center, Shanghai, People's Republic of China (L.J., X.M.); State Key Laboratory of Proteomics, Genetic Laboratory of Development and Diseases, Institute of Biotechnology, Beijing, People's Republic of China (Y.L., X.Y.); Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (X.L., J.Z.); Cyrus Tang Hematology Center, Soochow University, Suzhou, People's Republic of China (L.Z.); Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (J.L.); and The Central Laboratory of The Eighth People's Hospital of Shanghai, Shanghai, People's Republic of China (X.W.)
| | - Xi Mo
- Department of Laboratory Medicine, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, People's Republic of China (Y.W.); Institute for Pediatric Translational Medicine, Shanghai Children's Medical Center, Shanghai, People's Republic of China (L.J., X.M.); State Key Laboratory of Proteomics, Genetic Laboratory of Development and Diseases, Institute of Biotechnology, Beijing, People's Republic of China (Y.L., X.Y.); Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (X.L., J.Z.); Cyrus Tang Hematology Center, Soochow University, Suzhou, People's Republic of China (L.Z.); Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (J.L.); and The Central Laboratory of The Eighth People's Hospital of Shanghai, Shanghai, People's Republic of China (X.W.)
| | - Yu Lan
- Department of Laboratory Medicine, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, People's Republic of China (Y.W.); Institute for Pediatric Translational Medicine, Shanghai Children's Medical Center, Shanghai, People's Republic of China (L.J., X.M.); State Key Laboratory of Proteomics, Genetic Laboratory of Development and Diseases, Institute of Biotechnology, Beijing, People's Republic of China (Y.L., X.Y.); Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (X.L., J.Z.); Cyrus Tang Hematology Center, Soochow University, Suzhou, People's Republic of China (L.Z.); Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (J.L.); and The Central Laboratory of The Eighth People's Hospital of Shanghai, Shanghai, People's Republic of China (X.W.)
| | - Xiao Yang
- Department of Laboratory Medicine, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, People's Republic of China (Y.W.); Institute for Pediatric Translational Medicine, Shanghai Children's Medical Center, Shanghai, People's Republic of China (L.J., X.M.); State Key Laboratory of Proteomics, Genetic Laboratory of Development and Diseases, Institute of Biotechnology, Beijing, People's Republic of China (Y.L., X.Y.); Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (X.L., J.Z.); Cyrus Tang Hematology Center, Soochow University, Suzhou, People's Republic of China (L.Z.); Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (J.L.); and The Central Laboratory of The Eighth People's Hospital of Shanghai, Shanghai, People's Republic of China (X.W.)
| | - Xinyi Liu
- Department of Laboratory Medicine, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, People's Republic of China (Y.W.); Institute for Pediatric Translational Medicine, Shanghai Children's Medical Center, Shanghai, People's Republic of China (L.J., X.M.); State Key Laboratory of Proteomics, Genetic Laboratory of Development and Diseases, Institute of Biotechnology, Beijing, People's Republic of China (Y.L., X.Y.); Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (X.L., J.Z.); Cyrus Tang Hematology Center, Soochow University, Suzhou, People's Republic of China (L.Z.); Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (J.L.); and The Central Laboratory of The Eighth People's Hospital of Shanghai, Shanghai, People's Republic of China (X.W.)
| | - Jian Zhang
- Department of Laboratory Medicine, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, People's Republic of China (Y.W.); Institute for Pediatric Translational Medicine, Shanghai Children's Medical Center, Shanghai, People's Republic of China (L.J., X.M.); State Key Laboratory of Proteomics, Genetic Laboratory of Development and Diseases, Institute of Biotechnology, Beijing, People's Republic of China (Y.L., X.Y.); Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (X.L., J.Z.); Cyrus Tang Hematology Center, Soochow University, Suzhou, People's Republic of China (L.Z.); Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (J.L.); and The Central Laboratory of The Eighth People's Hospital of Shanghai, Shanghai, People's Republic of China (X.W.)
| | - Li Zhu
- Department of Laboratory Medicine, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, People's Republic of China (Y.W.); Institute for Pediatric Translational Medicine, Shanghai Children's Medical Center, Shanghai, People's Republic of China (L.J., X.M.); State Key Laboratory of Proteomics, Genetic Laboratory of Development and Diseases, Institute of Biotechnology, Beijing, People's Republic of China (Y.L., X.Y.); Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (X.L., J.Z.); Cyrus Tang Hematology Center, Soochow University, Suzhou, People's Republic of China (L.Z.); Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (J.L.); and The Central Laboratory of The Eighth People's Hospital of Shanghai, Shanghai, People's Republic of China (X.W.)
| | - Junling Liu
- Department of Laboratory Medicine, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, People's Republic of China (Y.W.); Institute for Pediatric Translational Medicine, Shanghai Children's Medical Center, Shanghai, People's Republic of China (L.J., X.M.); State Key Laboratory of Proteomics, Genetic Laboratory of Development and Diseases, Institute of Biotechnology, Beijing, People's Republic of China (Y.L., X.Y.); Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (X.L., J.Z.); Cyrus Tang Hematology Center, Soochow University, Suzhou, People's Republic of China (L.Z.); Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (J.L.); and The Central Laboratory of The Eighth People's Hospital of Shanghai, Shanghai, People's Republic of China (X.W.)
| | - Xiaolin Wu
- Department of Laboratory Medicine, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, People's Republic of China (Y.W.); Institute for Pediatric Translational Medicine, Shanghai Children's Medical Center, Shanghai, People's Republic of China (L.J., X.M.); State Key Laboratory of Proteomics, Genetic Laboratory of Development and Diseases, Institute of Biotechnology, Beijing, People's Republic of China (Y.L., X.Y.); Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (X.L., J.Z.); Cyrus Tang Hematology Center, Soochow University, Suzhou, People's Republic of China (L.Z.); Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China (J.L.); and The Central Laboratory of The Eighth People's Hospital of Shanghai, Shanghai, People's Republic of China (X.W.)
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14
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Todinova S, Komsa-Penkova R, Krumova S, Taneva SG, Golemanov G, Georgieva G, Tonchev P, Tsankov B, Beshev L, Balashev K, Andreeva TD. PlA2 Polymorphism in Glycoprotein IIb/IIIa Modulates the Morphology and Nanomechanics of Platelets. Clin Appl Thromb Hemost 2017; 23:951-960. [PMID: 28081621 DOI: 10.1177/1076029616687847] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Glycoprotein IIb/IIIa (GPIIb/IIIa) is the most abundant platelet surface receptor for fibrinogen and von Willebrand factor. Polymorphism PlA1/A2 in the gene of GPIIb/IIIa is among the risk factors for the development of arterial and venous thrombosis. The aim of this study is to evaluate the effect of the carriage of PlA1/A2 on the size, topographic features, and membrane stiffness of platelets from healthy controls and patients with deep venous thrombosis (DVT). Atomic force microscopy (AFM) imaging and nanoindentation (force-distance curves) were applied to investigate the morphological and nanomechanical properties (Young's modulus) of platelets immobilized on glass surface. The surface roughness ( Ra) and height ( h) of platelets from patients with DVT, carriers of mutant allele PlA2 ( Ra = 30.2 ± 6 nm; h = 766 ± 182 nm) and noncarriers ( Ra = 28.6 ± 6 nm; h = 865 ± 290 nm), were lower than those of healthy carriers of allele PlA2 ( Ra = 48.1 ± 12 nm; h = 1072 ± 338 nm) and healthy noncarriers ( Ra = 49.7 ± 14 nm; h = 1021 ± 433 nm), respectively. Platelets isolated from patients with DVT, both carriers and noncarriers, exhibit much higher degree of stiffness at the stage of spreading ( E = 327 ± 85 kPa and 341 ± 102 kPa, respectively) compared to healthy noncarriers ( E = 198 ± 50 kPa). In addition, more pronounced level of platelet activation was found in polymorphism carriers. In conclusion, the carriage of PlA2 allele modulates the activation state, morphology, and membrane elasticity of platelets.
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Affiliation(s)
- Svetla Todinova
- 1 Department of Biomacromolecules and Biomolecular Interactions, Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | | | - Sashka Krumova
- 1 Department of Biomacromolecules and Biomolecular Interactions, Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Stefka G Taneva
- 1 Department of Biomacromolecules and Biomolecular Interactions, Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Georgy Golemanov
- 2 Department of Biochemistry, Medical University, Pleven, Bulgaria
| | - Galia Georgieva
- 2 Department of Biochemistry, Medical University, Pleven, Bulgaria
| | - Pencho Tonchev
- 3 Department of Surgery, University Hospital, Pleven, Bulgaria
| | - Boris Tsankov
- 3 Department of Surgery, University Hospital, Pleven, Bulgaria
| | - Lyubomir Beshev
- 3 Department of Surgery, University Hospital, Pleven, Bulgaria
| | - Konstantin Balashev
- 4 Department of Physical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University, Sofia, Bulgaria
| | - Tonya D Andreeva
- 1 Department of Biomacromolecules and Biomolecular Interactions, Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria
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15
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Akbar H, Duan X, Saleem S, Davis AK, Zheng Y. RhoA and Rac1 GTPases Differentially Regulate Agonist-Receptor Mediated Reactive Oxygen Species Generation in Platelets. PLoS One 2016; 11:e0163227. [PMID: 27681226 PMCID: PMC5040254 DOI: 10.1371/journal.pone.0163227] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Accepted: 09/06/2016] [Indexed: 12/19/2022] Open
Abstract
Agonist induced generation of reactive oxygen species (ROS) by NADPH oxidases (NOX) enhances platelet aggregation and hence the risk of thrombosis. RhoA and Rac1 GTPases are involved in ROS generation by NOX in a variety of cells, but their roles in platelet ROS production remain unclear. In this study we used platelets from RhoA and Rac1 conditional knockout mice as well as human platelets treated with Rhosin and NSC23767, rationally designed small molecule inhibitors of RhoA and Rac GTPases, respectively, to better define the contributions of RhoA and Rac1 signaling to ROS generation and platelet activation. Treatment of platelets with Rhosin inhibited: (a) U46619 induced activation of RhoA; (b) phosphorylation of p47phox, a critical component of NOX; (c) U46619 or thrombin induced ROS generation; (d) phosphorylation of myosin light chain (MLC); (e) platelet shape change; (f) platelet spreading on immobilized fibrinogen; and (g) release of P-selectin, secretion of ATP and aggregation. Conditional deletion of RhoA or Rac1 gene inhibited thrombin induced ROS generation in platelets. Addition of Y27632, a RhoA inhibitor, NSC23766 or Phox-I, an inhibitor of Rac1-p67phox interaction, to human platelets blocked thrombin induced ROS generation. These data suggest that: (a) RhoA/ROCK/p47phox signaling axis promotes ROS production that, at least in part, contributes to platelet activation in conjunction with or independent of the RhoA/ROCK mediated phosphorylation of MLC; and (b) RhoA and Rac1 differentially regulate ROS generation by inhibiting phosphorylation of p47phox and Rac1-p67phox interaction, respectively.
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Affiliation(s)
- Huzoor Akbar
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, 45701, United States of America
- * E-mail:
| | - Xin Duan
- Division of Experimental Hematology and Cancer Biology, Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, OH, 45229, United States of America
| | - Saima Saleem
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, 45701, United States of America
| | - Ashley K. Davis
- Division of Experimental Hematology and Cancer Biology, Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, OH, 45229, United States of America
| | - Yi Zheng
- Division of Experimental Hematology and Cancer Biology, Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, OH, 45229, United States of America
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16
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Cevik O, Baykal AT, Sener A. Platelets Proteomic Profiles of Acute Ischemic Stroke Patients. PLoS One 2016; 11:e0158287. [PMID: 27336623 PMCID: PMC4919045 DOI: 10.1371/journal.pone.0158287] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 06/13/2016] [Indexed: 12/20/2022] Open
Abstract
Platelets play a crucial role in the pathogenesis of stroke and antiplatelet agents exist for its treatment and prevention. Through the use of LC-MS based protein expression profiling, platelets from stroke patients were analyzed and then correlated with the proteomic analyses results in the context of this disease. This study was based on patients who post ischemic stroke were admitted to hospital and had venous blood drawn within 24 hrs of the incidence. Label-free protein expression analyses of the platelets' tryptic digest was performed in triplicate on a UPLC-ESI-qTOF-MS/MS system and ProteinLynx Global Server (v2.5, Waters) was used for tandem mass data extraction. The peptide sequences were searched against the reviewed homo sapiens database (www.uniprot.org) and the quantitation of protein variation was achieved through Progenesis LC-MS software (V4.0, Nonlinear Dynamics). These Label-free differential proteomics analysis of platelets ensured that 500 proteins were identified and 83 of these proteins were found to be statistically significant. The differentially expressed proteins are involved in various processes such as inflammatory response, cellular movement, immune cell trafficking, cell-to-cell signaling and interaction, hematological system development and function and nucleic acid metabolism. The expressions of myeloperoxidase, arachidonate 12-Lipoxygenase and histidine-rich glycoprotein are involved in cellular metabolic processes, crk-like protein and ras homolog gene family member A involved in cell signaling with vitronectin, thrombospondin 1, Integrin alpha 2b, and integrin beta 3 involved in cell adhesion. Apolipoprotein H, immunoglobulin heavy constant gamma 1 and immunoglobulin heavy constant gamma 3 are involved in structural, apolipoprotein A-I, and alpha-1-microglobulin/bikunin precursor is involved in transport, complement component 3 and clusterin is involved in immunity proteins as has been discussed. Our data provides an insight into the proteins that are involved in the platelets' activation response during ischemic stroke. It could be argued that this study lays the foundation for future mechanistic studies.
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Affiliation(s)
- Ozge Cevik
- Cumhuriyet University, Faculty of Pharmacy, Department of Biochemistry, Sivas, Turkey
- Marmara University, Faculty of Pharmacy, Department of Biochemistry, Istanbul, Turkey
- * E-mail:
| | - Ahmet Tarik Baykal
- Acibadem University, School of Medicine, Department of Medical Biochemistry, Istanbul, Turkey
| | - Azize Sener
- Marmara University, Faculty of Pharmacy, Department of Biochemistry, Istanbul, Turkey
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17
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Schubert P, Coupland D, Nombalais M, M Walsh G, Devine DV. RhoA/ROCK signaling contributes to sex differences in the activation of human platelets. Thromb Res 2016; 139:50-5. [PMID: 26916296 DOI: 10.1016/j.thromres.2016.01.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 12/18/2015] [Accepted: 01/10/2016] [Indexed: 02/08/2023]
Abstract
Studies of sex-dependent differences in platelet aggregation and glycoprotein (GP)IIb/IIIa activation have demonstrated that platelets from females are more sensitive to agonists than those from males. To date, there is little understanding of these differences at a molecular level. Here, sex differences in reactivity of platelets from 86 women and 86 men were investigated. Platelet degranulation (CD62P expression) and activation of GPIIb/IIIa (PAC-1 binding), with and without ADP, were assessed. Extent of shape change (ESC) in response to ADP was measured. Basal CD62P and PAC-1 expression did not differ between the sexes. In response to ADP activation, mean PAC-1 binding in platelets from female donors was 17.9±3.5% vs. 14.0±4.1% in platelets from male donors, and ESC was significantly greater in platelets from females (p<0.05). Evaluation of basal expression of signaling molecules along the ADP receptor pathway leading to GPIIb/IIIa activation and subsequent RhoA/ROCK signaling via GPIIb/IIIa 'outside-in' signaling showed that platelets from females produce 3-fold greater levels of phosphorylated protein kinase C (PKC) substrates. There was a 2.5-fold greater level of activated RhoA, and platelet sub-fractionation analysis demonstrated 2.7-fold more RhoA in the membrane fraction of female vs. male platelets. Similarly, there was a 2.8-fold increase in levels of phosphorylated myosin light chain (MLC) in platelets from females vs. males. The increased signaling activity in platelets from females mirrors their greater sensitivity to agonists. These findings further our understanding of the molecular differences between platelets from males and females.
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Affiliation(s)
- Peter Schubert
- Centre for Innovation, Canadian Blood Services, Vancouver, BC, Canada; Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada; Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Danielle Coupland
- Centre for Innovation, Canadian Blood Services, Vancouver, BC, Canada; Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - Marie Nombalais
- Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - Geraldine M Walsh
- Centre for Innovation, Canadian Blood Services, Vancouver, BC, Canada; Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - Dana V Devine
- Centre for Innovation, Canadian Blood Services, Vancouver, BC, Canada; Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada; Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.
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18
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Huynh K, Gyenes M, Hollenberg CP, Nguyen TH, Van Vo T, Stoldt VR. Fibronectin unfolded by adherent but not suspended platelets: An in vitro explanation for its dual role in haemostasis. Thromb Res 2015; 136:803-12. [DOI: 10.1016/j.thromres.2015.08.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 06/30/2015] [Accepted: 08/03/2015] [Indexed: 12/28/2022]
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19
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Abstract
MLCP (myosin light chain phosphatase) regulates platelet function through its ability to control myosin IIa phosphorylation. Recent evidence suggests that MLCP is a de facto target for signalling events stimulated by cAMP. In the present mini-review, we discuss the mechanisms by which cAMP signalling maintains MLCP in an active state to control platelet contractile machinery.
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20
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Elvers M. RhoGAPs and Rho GTPases in platelets. Hamostaseologie 2015; 36:168-77. [PMID: 25639730 DOI: 10.5482/hamo-14-09-0046] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 01/13/2015] [Indexed: 01/03/2023] Open
Abstract
Platelet cytoskeletal reorganization is essential for platelet adhesion and thrombus formation in hemostasis and thrombosis. The Rho GTPases RhoA, Rac1 and Cdc42 are the main players in cytoskeletal dynamics of platelets responsible for the formation of filopodia and lamellipodia to strongly increase the platelet surface upon activation. They are involved in platelet activation and aggregate formation including platelet secretion, integrin activation and arterial thrombus formation. The activity of Rho GTPases is tightly controlled by different proteins such as GTPase-activating proteins (GAPs). GAPs stimulate GTP hydrolysis to terminate Rho signaling. The role and impact of GAPs in platelets is not well-defined and many of the RhoGAPs identified are not known to be present in platelets or to have any function in platelets. The recently identified RhoGAPs Oligophrenin1 (OPHN1) and Nadrin regulate the activity of RhoA, Rac1 and Cdc42 and subsequent platelet cytoskeletal reorganization, platelet activation and thrombus formation. In the last years, the analysis of genetically modified mice helped to gain the understanding of Rho GTPases and their regulators in cytoskeletal rearrangements and other Rho mediated cellular processes in platelets.
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Affiliation(s)
- Margitta Elvers
- Margitta Elvers, Ph.D., Department of Clinical and Experimental Hemostasis, Hemotherapy and Transfusion Medicine, Heinrich-Heine-University Duesseldorf, Moorenstr. 5, 40225 Duesseldorf, Germany, Tel. +49/(0)211/81-08851, Fax -17498., E-mail:
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21
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Mehrbod M, Trisno S, Mofrad MRK. On the activation of integrin αIIbβ3: outside-in and inside-out pathways. Biophys J 2014; 105:1304-15. [PMID: 24047981 DOI: 10.1016/j.bpj.2013.07.055] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 06/06/2013] [Accepted: 07/02/2013] [Indexed: 01/05/2023] Open
Abstract
Integrin αIIbβ3 is a member of the integrin family of transmembrane proteins present on the plasma membrane of platelets. Integrin αIIbβ3 is widely known to regulate the process of thrombosis via activation at its cytoplasmic side by talin and interaction with the soluble fibrinogen. It is also reported that three groups of interactions restrain integrin family members in the inactive state, including a set of salt bridges on the cytoplasmic side of the transmembrane domain of the integrin α- and β-subunits known as the inner membrane clasp, hydrophobic packing of a few transmembrane residues on the extracellular side between the α- and β-subunits that is known as the outer membrane clasp, and the key interaction group of the βA domain (located on the β-subunit head domain) with the βTD (proximal to the plasma membrane on the β-subunit). However, molecular details of this key interaction group as well as events that lead to detachment of the βTD and βA domains have remained ambiguous. In this study, we use molecular dynamics models to take a comprehensive outside-in and inside-out approach at exploring how integrin αIIbβ3 is activated. First, we show that talin's interaction with the membrane-proximal and membrane-distal regions of integrin cytoplasmic-transmembrane domains significantly loosens the inner membrane clasp. Talin also interacts with an additional salt bridge (R734-E1006), which facilitates integrin activation through the separation of the integrin's α- and β-subunits. The second part of our study classifies three types of interactions between RGD peptides and the extracellular domains of integrin αIIbβ3. Finally, we show that the interaction of the Arg of the RGD sequence may activate integrin via disrupting the key interaction group between K350 on the βA domain and S673/S674 on the βTD.
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Affiliation(s)
- Mehrdad Mehrbod
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, California; and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
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22
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Suzuki A, Shin JW, Wang Y, Min SH, Poncz M, Choi JK, Discher DE, Carpenter CL, Lian L, Zhao L, Wang Y, Abrams CS. RhoA is essential for maintaining normal megakaryocyte ploidy and platelet generation. PLoS One 2013; 8:e69315. [PMID: 23935982 PMCID: PMC3720647 DOI: 10.1371/journal.pone.0069315] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 06/07/2013] [Indexed: 12/17/2022] Open
Abstract
RhoA plays a multifaceted role in platelet biology. During platelet development, RhoA has been proposed to regulate endomitosis, proplatelet formation, and platelet release, in addition to having a role in platelet activation. These processes were previously studied using pharmacological inhibitors in vitro, which have potential drawbacks, such as non-specific inhibition or incomplete disruption of the intended target proteins. Therefore, we developed a conditional knockout mouse model utilizing the CRE-LOX strategy to ablate RhoA, specifically in megakaryocytes and in platelets to determine its role in platelet development. We demonstrated that deleting RhoA in megakaryocytes in vivo resulted in significant macrothrombocytopenia. RhoA-null megakaryocytes were larger, had higher mean ploidy, and exhibited stiff membranes with micropipette aspiration. However, in contrast to the results observed in experiments relying upon pharmacologic inhibitors, we did not observe any defects in proplatelet formation in megakaryocytes lacking RhoA. Infused RhoA-null megakaryocytes rapidly released platelets, but platelet levels rapidly plummeted within several hours. Our evidence supports the hypothesis that changes in membrane rheology caused infused RhoA-null megakaryocytes to prematurely release aberrant platelets that were unstable. These platelets were cleared quickly from circulation, which led to the macrothrombocytopenia. These observations demonstrate that RhoA is critical for maintaining normal megakaryocyte development and the production of normal platelets.
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Affiliation(s)
- Aae Suzuki
- Department of Hematology/Oncology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jae-Won Shin
- Pharmacology Medicine, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Yuhuan Wang
- Division of Hematology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Sang H. Min
- Department of Hematology/Oncology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Morty Poncz
- Division of Hematology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - John K. Choi
- Hematopathology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Dennis E. Discher
- Pharmacology Medicine, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Chris L. Carpenter
- Clinical Oncology, GlaxoSmithKline, Philadelphia, Pennsylvania, United States of America
| | - Lurong Lian
- Department of Hematology/Oncology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Liang Zhao
- Department of Hematology/Oncology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Yangfeng Wang
- Department of Hematology/Oncology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Charles S. Abrams
- Department of Hematology/Oncology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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23
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Goggs R, Savage JS, Mellor H, Poole AW. The small GTPase Rif is dispensable for platelet filopodia generation in mice. PLoS One 2013; 8:e54663. [PMID: 23359340 PMCID: PMC3554654 DOI: 10.1371/journal.pone.0054663] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 12/13/2012] [Indexed: 11/18/2022] Open
Abstract
Background Formation of filopodia and other shape change events are vital for platelet hemostatic function. The mechanisms regulating filopodia formation by platelets are incompletely understood however. In particular the small GTPase responsible for initiating filopodia formation by platelets remains elusive. The canonical pathway involving Cdc42 is not essential for filopodia formation in mouse platelets. The small GTPase Rif (RhoF) provides an alternative route to filopodia generation in other cell types and is expressed in both human and mouse platelets. Hypothesis/Objective We hypothesized that Rif might be responsible for generating filopodia by platelets and generated a novel knockout mouse model to investigate the functional role of Rif in platelets. Methodology/Principal Findings Constitutive RhoF−/− mice are viable and have normal platelet, leukocyte and erythrocyte counts and indices. RhoF−/− platelets form filopodia and spread normally on various agonist surfaces in static conditions and under arterial shear. In addition, RhoF−/− platelets have normal actin dynamics, are able to activate and aggregate normally and secrete from alpha and dense granules in response to collagen related peptide and thrombin stimulation. Conclusions The small GTPase Rif does not appear to be critical for platelet function in mice. Functional overlap between Rif and other small GTPases may be responsible for the non-essential role of Rif in platelets.
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Affiliation(s)
- Robert Goggs
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Joshua S. Savage
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Harry Mellor
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Alastair W. Poole
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
- * E-mail:
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24
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Wieschhaus AJ, Le Breton GC, Chishti AH. Headpiece domain of dematin regulates calcium mobilization and signaling in platelets. J Biol Chem 2012; 287:41218-31. [PMID: 23060452 DOI: 10.1074/jbc.m112.364679] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dematin is a broadly expressed membrane cytoskeletal protein that has been well characterized in erythrocytes and to a lesser extent in non-erythroid cells. However, dematin's function in platelets is not known. Here, we show that dematin is abundantly expressed in both human and mouse platelets. Platelets harvested from the dematin headpiece knock-out (HPKO) mouse model exhibit a striking defect in the mobilization of calcium in response to multiple agonists of platelet activation. The reduced calcium mobilization in HPKO platelets is associated with concomitant inhibition of platelet aggregation and granule secretion. Integrin α(IIb)β(3) activation in response to agonists is attenuated in the HPKO platelets. The mutant platelets show nearly normal spreading on fibrinogen and an unaltered basal cAMP level; however, the clot retraction was compromised in the mutant mice. Immunofluorescence analysis indicated that dematin is present both at the dense tubular system and plasma membrane fractions of platelets. Proteomic analysis of dematin-associated proteins in human platelets identified inositol 1,4,5-trisphosphate 3-kinase isoform B (IP3KB) as a binding partner, which was confirmed by immunoprecipitation analysis. IP3KB, a dense tubular system protein, is a major regulator of calcium homeostasis. Loss of the dematin headpiece resulted in a decrease of IP3KB at the membrane and increased levels of IP3KB in the cytosol. Collectively, these findings unveil dematin as a novel regulator of internal calcium mobilization in platelets affecting multiple signaling and cytoskeletal functions. Implications of a conserved role of dematin in the regulation of calcium homeostasis in other cell types will be discussed.
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Affiliation(s)
- Adam J Wieschhaus
- Department of Molecular Physiology and Pharmacology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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Abstract
INTRODUCTION Stroke is the third leading cause of death and a major cause of long-term disability in the adult population. Growing evidence suggests that inflammation may play an important role in the evolution of stroke. Because Rho-associated coiled-coil containing kinases (ROCKs) are important mediators of inflammation, they may contribute to stroke and stroke recovery. AREAS COVERED The pathophysiological role of ROCKs in mediating inflammation at different phases of stroke, and the therapeutic opportunities for stroke prevention and stroke treatment with ROCK inhibitors will be discussed. EXPERT OPINION Inflammation is a double-edged sword during the evolution of stroke. Immunomodulation might provide a novel therapeutic approach for stroke prevention and stroke treatment. ROCK plays an important role in mediating the inflammatory response following vascular injury as well as platelet activation and thrombus formation. ROCK inhibitors have been shown to be beneficial in stroke prevention, acute neuroprotection and chronic stroke recovery by affecting inflammatory-mediated platelet and endothelial function, smooth muscle contraction and neuronal regeneration. Thus, ROCK-mediated inflammation could be a potential therapeutic target for stroke prevention and stroke treatment. However, the mechanism by which ROCKs regulate the inflammatory response is unclear, and the role of the two ROCK isoforms in stroke and stroke recovery remains to be determined.
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Affiliation(s)
- Qing Mei Wang
- Spaulding Rehabilitation Hospital, Department of Physical Medicine and Rehabilitation, Boston, MA, USA
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Megakaryocyte-specific RhoA deficiency causes macrothrombocytopenia and defective platelet activation in hemostasis and thrombosis. Blood 2012; 119:1054-63. [DOI: 10.1182/blood-2011-08-372193] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Abstract
Vascular injury initiates rapid platelet activation that is critical for hemostasis, but it also may cause thrombotic diseases, such as myocardial infarction or ischemic stroke. Reorganizations of the platelet cytoskeleton are crucial for platelet shape change and secretion and are thought to involve activation of the small GTPase RhoA. In this study, we analyzed the in vitro and in vivo consequences of megakaryocyte- and platelet-specific RhoA gene deletion in mice. We found a pronounced macrothrombocytopenia in RhoA-deficient mice, with platelet counts of approximately half that of wild-type controls. The mutant cells displayed an altered shape but only a moderately reduced life span. Shape change of RhoA-deficient platelets in response to G13-coupled agonists was abolished, and it was impaired in response to Gq stimulation. Similarly, RhoA was required for efficient secretion of α and dense granules downstream of G13 and Gq. Furthermore, RhoA was essential for integrin-mediated clot retraction but not for actomyosin rearrangements and spreading of activated platelets on fibrinogen. In vivo, RhoA deficiency resulted in markedly prolonged tail bleeding times but also significant protection in different models of arterial thrombosis and in a model of ischemic stroke. Together, these results establish RhoA as an important regulator of platelet function in thrombosis and hemostasis.
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Thomas SG, Calaminus SDJ, Machesky LM, Alberts AS, Watson SP. G-protein coupled and ITAM receptor regulation of the formin FHOD1 through Rho kinase in platelets. J Thromb Haemost 2011; 9:1648-51. [PMID: 21605332 DOI: 10.1111/j.1538-7836.2011.04357.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Choi W, Karim ZA, Whiteheart SW. Protein expression in platelets from six species that differ in their open canalicular system. Platelets 2011; 21:167-75. [PMID: 20196629 DOI: 10.3109/09537101003611385] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Platelets contain an invaginated, tubular membranous structure called the surface-connected open canalicular system (SCCS or OCS), which is contiguous with the plasma membrane and serves as a site for granule fusion and as a reservoir of membrane for platelet spreading. According to ultrastructural studies, platelets from some species lack OCS. In an attempt to correlate biochemical and functional attributes with the presence of an OCS, platelets from human, mouse and dog (OCS(+)), and from cow, camel and horse (OCS(-)) were analysed for differential protein expression and aggregation in response to thrombin. Among the 18 different cytoskeletal and regulatory proteins examined, five (Rac1, RhoA, Ras, calmodulin and Src) were expressed at higher levels in OCS(+) platelets (p < 0.05). Given the role of Arf6 in the formation of tubular invaginations in nucleated cells, the levels of Arf6-GTP were analysed in OCS(+) and OCS(-) platelets. There was no significant correlation between the presence of OCS and total Arf6 or Arf6-GTP levels. Comparison of platelet aggregation between different species suggests that OCS(-) platelets have delayed responses. This comparison of platelets from six different species, which differ in their OCS, shows the differential expression of known signaling components and foreshadows future studies focusing on OCS formation and function.
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Affiliation(s)
- Wangsun Choi
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536-0509, USA
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Lasne D, Baujat G, Mirault T, Lunardi J, Grelac F, Egot M, Salomon R, Bachelot-Loza C. Bleeding disorders in Lowe syndrome patients: evidence for a link between OCRL mutations and primary haemostasis disorders. Br J Haematol 2010; 150:685-8. [PMID: 20629659 DOI: 10.1111/j.1365-2141.2010.08304.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Lowe syndrome (LS) is a rare X-linked disorder caused by mutations in the oculocerebrorenal gene (OCRL), encoding OCRL, a phosphatidylinositol 5-phosphatase with a RhoGAP domain. An abnormal rate of haemorrhagic events was found in a retrospective clinical survey. Herein, we report the results of exploration of haemostasis in six LS patients. All patients had normal coagulation tests but prolonged closure times (CTs) in the PFA-100 system. Healthy donors' blood samples incubated with a RhoA kinase inhibitor had prolonged CTs. This suggests that an aberrant RhoA pathway in platelets contributes to CT prolongation and primary haemostasis disorders in LS.
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Affiliation(s)
- Dominique Lasne
- AP-HP Hôpital Necker, Laboratoire d'Hématologie, Paris, France.
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Mitsios JV, Prévost N, Kasirer-Friede A, Gutierrez E, Groisman A, Abrams CS, Wang Y, Litvinov RI, Zemljic-Harpf A, Ross RS, Shattil SJ. What is vinculin needed for in platelets? J Thromb Haemost 2010; 8:2294-304. [PMID: 20670372 PMCID: PMC2965783 DOI: 10.1111/j.1538-7836.2010.03998.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
UNLABELLED Summary. BACKGROUND Vinculin links integrins to the cell cytoskeleton by virtue of its binding to proteins such as talin and F-actin. It has been implicated in the transmission of mechanical forces from the extracellular matrix to the cytoskeleton of migrating cells. Vinculin's function in platelets is unknown. OBJECTIVE To determine whether vinculin is required for the functions of platelets and their major integrin, α(IIb) β(3) . METHODS The murine vinculin gene (Vcl) was deleted in the megakaryocyte/platelet lineage by breeding Vcl fl/fl mice with Pf4-Cre mice. Platelet and integrin functions were studied in vivo and ex vivo. RESULTS Vinculin was undetectable in platelets from Vcl fl/fl Cre(+) mice, as determined by immunoblotting and fluorescence microscopy. Vinculin-deficient megakaryocytes exhibited increased membrane tethers in response to mechanical pulling on α(IIb) β(3) with laser tweezers, suggesting that vinculin helps to maintain membrane cytoskeleton integrity. Surprisingly, vinculin-deficient platelets displayed normal agonist-induced fibrinogen binding to α(IIb) β(3) , aggregation, spreading, actin polymerization/organization, clot retraction and the ability to form a procoagulant surface. Furthermore, vinculin-deficient platelets adhered to immobilized fibrinogen or collagen normally, under both static and flow conditions. Tail bleeding times were prolonged in 59% of vinculin-deficient mice. However, these mice exhibited no spontaneous bleeding and they formed occlusive platelet thrombi comparable to those in wild-type littermates in response to carotid artery injury with FeCl(3) . CONCLUSION Despite promoting membrane cytoskeleton integrity when mechanical force is applied to α(IIb) β(3) , vinculin is not required for the traditional functions of α(IIb) β(3) or the platelet actin cytoskeleton.
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Affiliation(s)
- John V. Mitsios
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Nicolas Prévost
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Ana Kasirer-Friede
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Edgar Gutierrez
- Department of Physics, University of California, San Diego, La Jolla, CA 92093
| | - Alex Groisman
- Department of Physics, University of California, San Diego, La Jolla, CA 92093
| | - Charles S. Abrams
- Department of Medicine and Cell, University of Pennsylvania School of Medicine, Philadelphia, PA 19104
| | - Yanfeng Wang
- Department of Medicine and Cell, University of Pennsylvania School of Medicine, Philadelphia, PA 19104
| | - Rustem I. Litvinov
- Department of Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104
| | - Alice Zemljic-Harpf
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093
- VA Healthcare San Diego, San Diego, CA 92161
| | - Robert S. Ross
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093
- VA Healthcare San Diego, San Diego, CA 92161
| | - Sanford J. Shattil
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093
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Tournoij E, Weber GJ, Akkerman JWN, de Groot PG, Zon LI, Moll FL, Schulte-Merker S. Mlck1a is expressed in zebrafish thrombocytes and is an essential component of thrombus formation. J Thromb Haemost 2010; 8:588-95. [PMID: 20002541 PMCID: PMC2935642 DOI: 10.1111/j.1538-7836.2009.03721.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND We have used the advantages of the zebrafish model system to demonstrate which of the vertebrate myosin light chain kinase (MLCK) genes is expressed in thrombocytes and important for thrombus formation. METHODS AND RESULTS Here we report that Mlck1a is an essential component of thrombus formation. Phylogenetic data revealed four zebrafish orthologous for three human MLCK genes. To investigate expression of the zebrafish mlck genes in thrombocytes we compared GFP-tagged platelets with other cells by microarray analysis, and showed that mlck1a expression was 4.5-fold enriched in platelets. Furthermore, mlck1a mRNA and mRNA for the platelet-specific cd41 co-localized in thrombi. Expression of other mlck subtypes was lower in GFP-tagged platelets (mlck1b; 0.77-fold enriched) and absent in thrombi (mlck1b, -2, -3). To investigate the role of Mlck1a in thrombus formation, we knocked down mlck1a using two morpholinos. This resulted in impaired morphology changes of platelets adhering on fibrinogen. In a thrombosis model, in which thrombocytes adhere to the vessel wall damaged by laser irradiation, thrombus formation was slowed down in mlck1a-deficient embryos. CONCLUSION We conclude that Mlck1a is the subtype of MLCK that contributes to platelet shape change and thrombus formation.
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Affiliation(s)
- E Tournoij
- Hubrecht Institute-KNAW and UMC, Utrecht, the Netherlands
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DeWard AD, Eisenmann KM, Matheson SF, Alberts AS. The role of formins in human disease. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1803:226-33. [PMID: 19941910 DOI: 10.1016/j.bbamcr.2009.11.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Revised: 11/06/2009] [Accepted: 11/10/2009] [Indexed: 02/02/2023]
Abstract
Formins are a conserved family of proteins that play key roles in cytoskeletal remodeling. They nucleate and processively elongate non-branched actin filaments and also modulate microtubule dynamics. Despite their significant contributions to cell biology and development, few studies have directly implicated formins in disease pathogenesis. This review highlights the roles of formins in cell division, migration, immunity, and microvesicle formation in the context of human disease. In addition, we discuss the importance of controlling formin activity and protein expression to maintain cell homeostasis.
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Affiliation(s)
- Aaron D DeWard
- Laboratory of Cell Structure and Signal Integration, Van Andel Research Institute, Grand Rapids, MI 49503, USA
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Gao G, Chen L, Dong B, Gu H, Dong H, Pan Y, Gao Y, Chen X. RhoA effector mDia1 is required for PI 3-kinase-dependent actin remodeling and spreading by thrombin in platelets. Biochem Biophys Res Commun 2009; 385:439-44. [DOI: 10.1016/j.bbrc.2009.05.090] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Accepted: 05/20/2009] [Indexed: 10/20/2022]
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Laschke MW, Dold S, Menger MD, Jeppsson B, Thorlacius H. The Rho-kinase inhibitor Y-27632 inhibits cholestasis-induced platelet interactions in the hepatic microcirculation. Microvasc Res 2009; 78:95-9. [PMID: 19374910 DOI: 10.1016/j.mvr.2009.04.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 03/06/2009] [Accepted: 04/07/2009] [Indexed: 10/20/2022]
Abstract
Bile duct obstruction is associated with hepatic accumulation of leukocytes and liver injury. Emerging data suggest that platelets may play an important role in tissue damage and inflammation. Herein, we characterized the platelet response in cholestatic liver injury and evaluated the role of Rho-kinase signaling. For this purpose, C57BL/6 mice were treated with the Rho-kinase inhibitor Y-27632 (10 mg/kg) and vehicle before undergoing bile duct ligation (BDL) for 12 h. Platelet rolling and adhesion, formation of platelet aggregates as well as microvascular perfusion in the liver were analyzed using intravital fluorescence microscopy. Liver damage was monitored by measuring serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Administration of Y-27632 reduced the BDL-associated increase of ALT and AST by 95% and 89%, respectively. The inhibition of Rho-kinase also reduced cholestasis-induced platelet rolling and adhesion by more than 46% and 73% in postsinusoidal venules and platelet adhesion in sinusoids by 60%. In addition, Y-27632 decreased platelet aggregation in hepatic sinusoids and postsinusoidal venules by 69% and 81%. BDL caused a significant reduction of hepatic microvascular perfusion. Importantly, pretreatment with Y-27632 restored sinusoidal perfusion in cholestatic animals. Our findings demonstrate that Rho-kinase regulates multiple aspects of platelet interaction in the microcirculation of cholestatic animals. Moreover, inhibition of Rho-kinase signaling not only attenuates platelet responses but also maintains microvascular perfusion and protects against hepatocellular injury in cholestasis. Thus, targeting Rho-kinase signaling may be an effective way to protect against platelet-mediated liver injury in obstructive jaundice.
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Affiliation(s)
- Matthias W Laschke
- Department of Surgery, Malmö University Hospital, Malmö, Lund University, Sweden.
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Jin J, Mao Y, Thomas D, Kim S, Daniel JL, Kunapuli SP. RhoA downstream of G(q) and G(12/13) pathways regulates protease-activated receptor-mediated dense granule release in platelets. Biochem Pharmacol 2008; 77:835-44. [PMID: 19073150 DOI: 10.1016/j.bcp.2008.11.017] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2008] [Revised: 11/13/2008] [Accepted: 11/14/2008] [Indexed: 11/17/2022]
Abstract
Platelet secretion is an important physiological event in hemostasis. The protease-activated receptors, PAR 1 and PAR 4, and the thromboxane receptor activate the G(12/13) pathways, in addition to the G(q) pathways. Here, we investigated the contribution of G(12/13) pathways to platelet dense granule release. 2MeSADP, which does not activate G(12/13) pathways, does not cause dense granule release in aspirin-treated platelets. However, supplementing 2MeSADP with YFLLRNP (60muM), as selective activator of G(12/13) pathways, resulted in dense granule release. Similarly, supplementing PLC activation with G(12/13) stimulation also leads to dense granule release. These results demonstrate that supplemental signaling from G(12/13) is required for G(q)-mediated dense granule release and that ADP fails to cause dense granule release because the platelet P2Y receptors, although activate PLC, do not activate G(12/13) pathways. When RhoA, downstream signaling molecule in G(12/13) pathways, is blocked, PAR-mediated dense granule release is inhibited. Furthermore, ADP activated RhoA downstream of G(q) and upstream of PLC. Finally, RhoA regulated PKCdelta T505 phosphorylation, suggesting that RhoA pathways contribute to platelet secretion through PKCdelta activation. We conclude that G(12/13) pathways, through RhoA, regulate dense granule release and fibrinogen receptor activation in platelets.
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Affiliation(s)
- Jianguo Jin
- Department of Physiology, Temple University School of Medicine, Philadelphia, PA, USA
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Calaminus SDJ, Thomas S, McCarty OJT, Machesky LM, Watson SP. Identification of a novel, actin-rich structure, the actin nodule, in the early stages of platelet spreading. J Thromb Haemost 2008; 6:1944-52. [PMID: 18761725 DOI: 10.1111/j.1538-7836.2008.03141.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND During platelet spreading, the actin cytoskeleton undergoes marked changes, forming filopodia, lamellipodia and stress fibres. In the present study, we report the identification of a novel actin-rich structure, termed an actin nodule, which appears prior to lamellipodia and stress fibre formation. METHODS Platelet spreading was monitored using human platelets and mouse GFP-actin platelets using real-time and end-point DIC, and fluorescent and electron microscopy (EM). RESULTS We identified a small, novel actin structure, the actin nodule, in the early stages of adhesion and spreading, which we hypothesize to be a precursor of lamellipodia and stress fibres. Nodule formation shows an inverse correlation to Rho kinase and myosin-II activity, is independent of PI3-kinase, but dependent on Src kinase activity. Actin nodules contain multiple proteins, including Arp2/3, Fyn, Rac, and beta1- and beta3- integrins, but not Src. EM analysis revealed that actin filaments extend in all directions from the nodules. Actin nodules are present on multiple matrices, including fibrinogen, laminin and VWF + botrocetin. CONCLUSION This work identifies a novel platelet actin structure, which we propose is a precursor to both lamellipodia and stress fibres and acts to drive platelet spreading.
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Affiliation(s)
- S D J Calaminus
- Centre for Cardiovascular Sciences, Institute of Biomedical Research, The Medical School, University of Birmingham, Birmingham, UK.
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Identification of a fibrin-independent platelet contractile mechanism regulating primary hemostasis and thrombus growth. Blood 2008; 112:90-9. [DOI: 10.1182/blood-2007-12-127001] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractA fundamental property of platelets is their ability to transmit cytoskeletal contractile forces to extracellular matrices. While the importance of the platelet contractile mechanism in regulating fibrin clot retraction is well established, its role in regulating the primary hemostatic response, independent of blood coagulation, remains ill defined. Real-time analysis of platelet adhesion and aggregation on a collagen substrate revealed a prominent contractile phase during thrombus development, associated with a 30% to 40% reduction in thrombus volume. Thrombus contraction developed independent of thrombin and fibrin and resulted in the tight packing of aggregated platelets. Inhibition of the platelet contractile mechanism, with the myosin IIA inhibitor blebbistatin or through Rho kinase antagonism, markedly inhibited thrombus contraction, preventing the tight packing of aggregated platelets and undermining thrombus stability in vitro. Using a new intravital hemostatic model, we demonstrate that the platelet contractile mechanism is critical for maintaining the integrity of the primary hemostatic plug, independent of thrombin and fibrin generation. These studies demonstrate an important role for the platelet contractile mechanism in regulating primary hemostasis and thrombus growth. Furthermore, they provide new insight into the underlying bleeding diathesis associated with platelet contractility defects.
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Watanabe N, Bodin L, Pandey M, Krause M, Coughlin S, Boussiotis VA, Ginsberg MH, Shattil SJ. Mechanisms and consequences of agonist-induced talin recruitment to platelet integrin alphaIIbbeta3. ACTA ACUST UNITED AC 2008; 181:1211-22. [PMID: 18573917 PMCID: PMC2442211 DOI: 10.1083/jcb.200803094] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Platelet aggregation requires agonist-induced αIIbβ3 activation, a process mediated by Rap1 and talin. To study mechanisms, we engineered αIIbβ3 Chinese hamster ovary (CHO) cells to conditionally express talin and protease-activated receptor (PAR) thrombin receptors. Human PAR1 or murine PAR4 stimulation activates αIIbβ3, which was measured with antibody PAC-1, indicating complete pathway reconstitution. Knockdown of Rap1–guanosine triphosphate–interacting adaptor molecule (RIAM), a Rap1 effector, blocks this response. In living cells, RIAM overexpression stimulates and RIAM knockdown blocks talin recruitment to αIIbβ3, which is monitored by bimolecular fluorescence complementation. Mutations in talin or β3 that disrupt their mutual interaction block both talin recruitment and αIIbβ3 activation. However, one talin mutant (L325R) is recruited to αIIbβ3 but cannot activate it. In platelets, RIAM localizes to filopodia and lamellipodia, and, in megakaryocytes, RIAM knockdown blocks PAR4-mediated αIIbβ3 activation. The RIAM-related protein lamellipodin promotes talin recruitment and αIIbβ3 activity in CHO cells but is not expressed in megakaryocytes or platelets. Thus, talin recruitment to αIIbβ3 by RIAM mediates agonist-induced αIIbβ3 activation, with implications for hemostasis and thrombosis.
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Affiliation(s)
- Naohide Watanabe
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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39
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Higashi T, Ikeda T, Shirakawa R, Kondo H, Kawato M, Horiguchi M, Okuda T, Okawa K, Fukai S, Nureki O, Kita T, Horiuchi H. Biochemical characterization of the Rho GTPase-regulated actin assembly by diaphanous-related formins, mDia1 and Daam1, in platelets. J Biol Chem 2008; 283:8746-55. [PMID: 18218625 DOI: 10.1074/jbc.m707839200] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The diaphanous-related formins are actin nucleating and elongating factors. They are kept in an inactive state by an intramolecular interaction between the diaphanous inhibitory domain (DID) and the diaphanous-autoregulatory domain (DAD). It is considered that the dissociation of this autoinhibitory interaction upon binding of GTP-bound Rho to the GTPase binding domain next to DID induces exposure of the FH1-FH2 domains, which assemble actin filaments. Here, we isolated two diaphanous-related formins, mDia1 and Daam1, in platelet extracts by GTP-RhoA affinity column chromatography. We characterized them by a novel assay, where beads coated with the FH1-FH2-DAD domains of either mDia1 or Daam1 were incubated with platelet cytosol, and the assembled actin filaments were observed after staining with rhodamine-phalloidin. Both formins generated fluorescent filamentous structures on the beads. Quantification of the fluorescence intensity of the beads revealed that the initial velocity in the presence of mDia1 was more than 10 times faster than in the presence of Daam1. The actin assembly activities of both FH1-FH2-DADs were inhibited by adding cognate DID domains. GTP-RhoA, -RhoB, and -RhoC, but not GTP-Rac1 or -Cdc42, bound to both mDia1 and Daam1 and efficiently neutralized the inhibition by the DID domains. The association between RhoA and Daam1 was induced by thrombin stimulation in platelets, and RhoA-bound endogenous formins induced actin assembly, which was inhibited by the DID domains of Daam1 and mDia1. Thus, mDia1 and Daam1 are platelet actin assembly factors having distinct efficiencies, and they are directly regulated by Rho GTPases.
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Affiliation(s)
- Tomohito Higashi
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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Roles of focal adhesion kinase (FAK) in megakaryopoiesis and platelet function: studies using a megakaryocyte lineage specific FAK knockout. Blood 2007; 111:596-604. [PMID: 17925492 DOI: 10.1182/blood-2007-05-089680] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Focal adhesion kinase (FAK) plays a key role in mediating signaling downstream of integrins and growth factor receptors. In this study, we determined the roles of FAK in vivo by generating a megakaryocyte lineage-specific FAK-null mouse (Pf4-Cre/FAK-floxed). Megakaryocyte and platelet FAK expression was ablated in Pf4-Cre/FAK-floxed mice without affecting expression of the FAK homologue PYK2, although PYK2 phosphorylation was increased in FAK-/- megakaryocytes in response to fibrinogen. Megakaryopoiesis is greatly enhanced in Pf4-Cre/FAK-floxed mice, with significant increases in megakaryocytic progenitors (CFU-MK), mature megakaryocytes, megakaryocyte ploidy, and moderate increases in resting platelet number and platelet recovery following a thrombocytopenic stress. Thrombopoietin (Tpo)-mediated activation of Lyn kinase, a negative regulator of megakaryopoiesis, is severely attenuated in FAK-null megakaryocytes compared with wild-type controls. In contrast, Tpo-mediated activation of positive megakaryopoiesis regulators such as ERK1/2 and AKT is increased in FAK-null megakaryocytes, providing a plausible explanation for the observed increases in megakaryopoiesis in these mice. In Pf4-Cre/FAK-floxed mice, rebleeding times are significantly increased, and FAK-null platelets exhibit diminished spreading on immobilized fibrinogen. These studies establish clear roles for FAK in megakaryocyte growth and platelet function, setting the stage for manipulation of this component of the Tpo signaling apparatus for therapeutic benefit.
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Calaminus SDJ, Auger JM, McCarty OJT, Wakelam MJO, Machesky LM, Watson SP. MyosinIIa contractility is required for maintenance of platelet structure during spreading on collagen and contributes to thrombus stability. J Thromb Haemost 2007; 5:2136-45. [PMID: 17645784 DOI: 10.1111/j.1538-7836.2007.02696.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND MyosinIIs are adenosine triphosphate-driven molecular motors that form part of a cell's contractile machinery. They are activated by phosphorylation of their light chains, by either activation of myosin light chain (MLC) kinase or inhibition of MLC phosphatase via Rho kinase (ROCK). MyosinIIa phosphorylation underlies platelet rounding and stress fiber formation. OBJECTIVE To identify the functional significance of myosinIIa in platelet spreading and thrombus formation on collagen using inhibitors of ROCK (Y27632) and myosinII (blebbistatin). RESULTS Stress fiber formation on collagen is inhibited by both Y27632 and blebbistatin. A substantial proportion of spread platelets generate internal holes or splits on collagen, presumably because of a reduction in contractile strength. Platelet integrity, however, is maintained. In an in vitro model, thrombus embolization on collagen is increased in the presence of Y27632 and blebbistatin at intermediate shear, leading to a reduction in platelet aggregate growth. Moreover, Y27632 causes a marked reduction in thrombus formation in an in vivo laser-injury model. CONCLUSIONS MyosinIIa contractility is required for maintenance of platelet structure during spreading on collagen and contributes to thrombus stability.
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Affiliation(s)
- S D J Calaminus
- Centre for Cardiovascular Sciences, Institute of Biomedical Research, The Medical School, University of Birmingham, Birmingham, UK.
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Huang JS, Dong L, Kozasa T, Le Breton GC. Signaling through G(alpha)13 switch region I is essential for protease-activated receptor 1-mediated human platelet shape change, aggregation, and secretion. J Biol Chem 2007; 282:10210-22. [PMID: 17298951 DOI: 10.1074/jbc.m605678200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
This study investigated the involvement of Galpha(13) switch region I (SRI) in protease-activated receptor 1 (PAR1)-mediated platelet function and signaling. To this end, myristoylated peptides representing the Galpha(13) SRI (Myr-G(13)SRI(pep)) and its random counterpart were evaluated for their effects on PAR1 activation. Initial studies demonstrated that Myr-G(13)SRI(pep) and Myr-G(13)SRI(Random-pep) were equally taken up by human platelets and did not interfere with PAR1-ligand interaction. Subsequent experiments revealed that Myr-G(13)SRI(pep) specifically bound to platelet RhoA guanine nucleotide exchange factor (p115RhoGEF) and blocked PAR1-mediated RhoA activation in platelets and human embryonic kidney cells. These results suggest a direct interaction of Galpha(13) SRI with p115RhoGEF and a mechanism for Myr-G(13)SRI(pep) inhibition of RhoA activation. Platelet function studies demonstrated that Myr-G(13)SRI(pep) specifically inhibited PAR1-stimulated shape change, aggregation, and secretion in a dose-dependent manner but did not inhibit platelet activation induced by either ADP or A23187. It was also found that Myr-G(13)SRI(pep) inhibited low dose, but not high dose, thrombin-induced aggregation. Additional experiments showed that PAR1-mediated calcium mobilization was partially blocked by Myr-G(13)SRI(pep) but not by the Rho kinase inhibitor Y-27632. Finally, Myr-G(13)SRI(pep) effectively inhibited PAR1-induced stress fiber formation and cell contraction in endothelial cells. Collectively, these results suggest the following: 1) interaction of Galpha(13) SRI with p115RhoGEF is required for G(13)-mediated RhoA activation in platelets; 2) signaling through the G(13) pathway is critical for PAR1-mediated human platelet functional changes and low dose thrombin-induced aggregation; and 3) G(13) signaling elicits calcium mobilization in human platelets through a Rho kinase-independent mechanism.
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Affiliation(s)
- Jin-Sheng Huang
- Department of Pharmacology, College of Medicine University of Illinois at Chicago, Chicago, Illinois 60612
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Mazharian A, Roger S, Berrou E, Adam F, Kauskot A, Nurden P, Jandrot-Perrus M, Bryckaert M. Protease-activating receptor-4 induces full platelet spreading on a fibrinogen matrix: involvement of ERK2 and p38 and Ca2+ mobilization. J Biol Chem 2007; 282:5478-87. [PMID: 17200114 DOI: 10.1074/jbc.m609881200] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although the involvement of protease-activating receptor PAR1 and PAR4 is well established in platelet aggregation, their role in platelet adhesion and spreading has yet to be characterized. We investigated platelet adhesion and spreading on a fibrinogen matrix after PAR1 and PAR4 stimulation in correlation with the activation of two MAPKs, ERK2 and p38. Of the two PAR-activating peptides (PAR-APs), PAR1-AP and PAR4-AP, which both induce adhesion, only PAR4-AP induced full platelet spreading. Although both PAR1-AP and PAR4-AP induced ADP secretion, which is required for platelet spreading, only PAR4-AP induced sustained Ca(2+) mobilization. In these conditions of PAR4 induction, ERK2 and p38 activation were involved in platelet spreading but not in platelet adhesion. p38 phosphorylation was dependent on ADP signaling through P2Y12, its receptor. ERK2 phosphorylation was triggered through integrin alphaIIbbeta3 outside-in signaling and was dependent on the Rho pathway. ERK2 and p38 activation induced phosphorylation of the myosin light chain and actin polymerization, respectively, necessary for cytoskeleton reorganization. These findings provide the first evidence that thrombin requires PAR4 for the full spreading response. ERK2 and p38 and sustained Ca(2+) mobilization, involved in PAR4-induced platelet spreading, contribute to the stabilization of platelet thrombi at sites of high thrombin production.
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Affiliation(s)
- Alexandra Mazharian
- U689 INSERM, IFR139, Hôpital Lariboisière, 8 rue Guy Patin, 75010 Paris, France
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Jeon OH, Kim D, Choi YJ, Kim SH, Choi WS, Kim DS. Novel function of human ADAM15 disintegrin-like domain and its derivatives in platelet aggregation. Thromb Res 2007; 119:609-19. [PMID: 16797059 DOI: 10.1016/j.thromres.2006.04.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 04/19/2006] [Accepted: 04/27/2006] [Indexed: 11/24/2022]
Abstract
INTRODUCTION A Disintegrin and Metalloproteinase (ADAM) proteins are a family of multifunctional proteins containing disintegrin and metalloproteinase domains that perform both adhesive and proteolytic functions in cell-cell and cell-matrix interactions. ADAM15 is unique among these proteins in having an Arg-Gly-Asp (RGD) motif in its disintegrin-like domain. This motif is known to interact with the integrin alphaIIbbeta3 on platelets. MATERIALS AND METHODS We cloned and expressed the human ADAM15 disintegrin-like domain and its derivatives in Pichia pastoris, and purified them by chromatographic fractionation. We then characterized the integrin binding specificities and their antiplatelet activities of the proteins. Antiplatelet function was assessed by inhibition of platelet adhesion and aggregation. RESULTS The yeast-expressed ADAM15 disintegrin-like domains were able to inhibit the binding of alphaIIbbeta3 as well as alphavbeta3 to its biological ligands in a dose-dependent manner. Remarkably, mutation of the three residues proximal to the RGD tripeptide sequence, RPTRGD sequence to NWKRGD, increased its affinity for alphaIIbbeta3. The NWK mutant had a much greater inhibitory action on human platelet aggregation than the original ADAM15 disintegrin-like domain. CONCLUSIONS The structural context of the RGD tripeptide sequence in the disintegrin domain determines the specificity and affinity of the protein for its binding partners. The human ADAM15 disintegrin-like domain may provide useful information for developing an antithrombotic agent.
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Affiliation(s)
- Ok-Hee Jeon
- Department of Biochemistry, College of Science, Yonsei University, Seoul, Republic of Korea
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Schwertz H, Tolley ND, Foulks JM, Denis MM, Risenmay BW, Buerke M, Tilley RE, Rondina MT, Harris EM, Kraiss LW, Mackman N, Zimmerman GA, Weyrich AS. Signal-dependent splicing of tissue factor pre-mRNA modulates the thrombogenicity of human platelets. ACTA ACUST UNITED AC 2006; 203:2433-40. [PMID: 17060476 PMCID: PMC2118136 DOI: 10.1084/jem.20061302] [Citation(s) in RCA: 272] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Tissue factor (TF) is an essential cofactor for the activation of blood coagulation in vivo. We now report that quiescent human platelets express TF pre-mRNA and, in response to activation, splice this intronic-rich message into mature mRNA. Splicing of TF pre-mRNA is associated with increased TF protein expression, procoagulant activity, and accelerated formation of clots. Pre-mRNA splicing is controlled by Cdc2-like kinase (Clk)1, and interruption of Clk1 signaling prevents TF from accumulating in activated platelets. Elevated intravascular TF has been reported in a variety of prothrombotic diseases, but there is debate as to whether anucleate platelets-the key cellular effector of thrombosis-express TF. Our studies demonstrate that human platelets use Clk1-dependent splicing pathways to generate TF protein in response to cellular activation. We propose that platelet-derived TF contributes to the propagation and stabilization of a thrombus.
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Affiliation(s)
- Hansjörg Schwertz
- Department of Internal Medicine, University of Utah, Salt Lake City, UT 84112, USA
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Suzuki-Inoue K, Hughes CE, Inoue O, Kaneko M, Cuyun-Lira O, Takafuta T, Watson SP, Ozaki Y. Involvement of Src kinases and PLCgamma2 in clot retraction. Thromb Res 2006; 120:251-8. [PMID: 17055557 PMCID: PMC1884692 DOI: 10.1016/j.thromres.2006.09.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2006] [Revised: 09/08/2006] [Accepted: 09/12/2006] [Indexed: 11/18/2022]
Abstract
The integrin αIIbβ3 plays a critical role in mediating clot retraction by platelets which is important in vivo in consolidating thrombus formation. Actin–myosin interaction is essential for clot retraction. In the present study, we demonstrate that the structurally distinct Src kinase inhibitors, PP2 and PD173952, significantly reduced the rate of clot retraction, but did not prevent it reaching completion. This effect was accompanied by abolition of αIIbβ3-dependent protein tyrosine phosphorylation, including PLCγ2. A role for PLCγ2 in mediating clot retraction was demonstrated using PLCγ2-deficient murine platelets. Furthermore, platelet adhesion to fibrinogen leads to MLC phosphorylation through a pathway that is inhibited by PP2 and by the PLC inhibitor, U73122. These results demonstrate a partial role for Src kinase-dependent activation of PLCγ2 and MLC phosphorylation in mediating clot retraction downstream of integrin αIIbβ3.
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Affiliation(s)
- Katsue Suzuki-Inoue
- Department of Clinical and Laboratory Medicine, Faculty of Medicine, Yamanashi University, 1110 Shimokato, Chuo, Yamanashi, 409-3898, Japan.
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Soriani A, Moran B, de Virgilio M, Kawakami T, Altman A, Lowell C, Eto K, Shattil SJ. A role for PKCtheta in outside-in alpha(IIb)beta3 signaling. J Thromb Haemost 2006; 4:648-55. [PMID: 16460447 DOI: 10.1111/j.1538-7836.2006.01806.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Fibrinogen binding to platelets triggers alpha(IIb)beta3-dependent outside-in signals that promote actin rearrangements and cell spreading. Studies with chemical inhibitors or activators have implicated protein kinase C (PKC) in alpha(IIb)beta3 function. However, the role of individual PKC isoforms is poorly understood. Biochemical and genetic approaches were used to determine whether PKCtheta is involved in alpha(IIb)beta3 signaling. PKCtheta was constitutively associated with alpha(IIb)beta3 in human and murine platelets. Fibrinogen binding to alpha(IIb)beta3 stimulated the association of PKCtheta with tyrosine kinases Btk and Syk, and tyrosine phosphorylation of PKCtheta, Btk and the actin regulator, Wiskott-Aldrich syndrome protein (WASP). Mouse platelets deficient in PKCtheta or Btk failed to spread on fibrinogen. Furthermore, PKCtheta was required for phosphorylation of WASP-interacting protein on Ser-488, an event that has been linked to WASP activation of the Arp2/3 complex and actin polymerization in lymphocytes. Neither PKCtheta nor Btk were required for agonist-induced inside-out signaling and fibrinogen binding to alpha(IIb)beta3. Thus, PKCtheta is a newly identified, essential member of a dynamic outside-in signaling complex that includes Btk and that couples alpha(IIb)beta3 to the actin cytoskeleton.
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Affiliation(s)
- A Soriani
- Division of Hematology-Oncology, Department of Medicine, University of California San Diego, La Jolla, CA, USA.
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Falet H, Chang G, Brohard-Bohn B, Rendu F, Hartwig JH. Integrin αIIbβ3signals lead cofilin to accelerate platelet actin dynamics. Am J Physiol Cell Physiol 2005; 289:C819-25. [PMID: 15901596 DOI: 10.1152/ajpcell.00587.2004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Cofilin, in its Ser3 dephosphorylated form, accelerates actin filament turnover in cells. We report here the role of cofilin in platelet actin assembly. Cofilin is primarily phosphorylated in the resting platelet as evidenced by a specific antibody directed against its Ser3 phosphorylated form. After stimulation with thrombin under nonstirring conditions, cofilin is reversibly dephosphorylated and transiently incorporates into the actin cytoskeleton. Its dephosphorylation is maximal 1–2 min after platelet stimulation, shortly after the peak of actin assembly occurs. Cofilin rephosphorylation begins 2 min after activation and exceeds resting levels by 5–10 min. Cofilin is dephosphorylated with identical kinetics but fails to become rephosphorylated when platelets are stimulated under stirring conditions. Cofilin is normally rephosphorylated when platelets are stimulated in the presence of Arg-Gly-Asp-Ser (RGDS) peptide or wortmannin to block αIIbβ3cross-linking and signaling or in platelets isolated from a patient with Glanzmann thrombasthenia, which express only 2–3% of normal αIIbβ3levels. Furthermore, actin assembly and Arp2/3 complex incorporation in the platelet actin cytoskeleton are decreased when αIIbβ3is engaged. Our results suggest that cofilin is essential for actin dynamics mediated by outside-in signals in activated platelets.
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Affiliation(s)
- Hervé Falet
- Division of Hematology, Brigham and Women's Hospital, Department of Medicine, Harvard Medical School, One Blackfan Circle, Karp 6, Boston, Massachusetts 02115, USA.
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Salsmann A, Schaffner-Reckinger E, Kabile F, Plançon S, Kieffer N. A New Functional Role of the Fibrinogen RGD Motif as the Molecular Switch That Selectively Triggers Integrin αIIbβ3-dependent RhoA Activation during Cell Spreading. J Biol Chem 2005; 280:33610-9. [PMID: 15955823 DOI: 10.1074/jbc.m500146200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
A number of RGD-type integrins rely on a synergistic site in addition to the canonical RGD site for ligand binding and signaling, although it is still unclear whether these two recognition sites function independently, synergistically, or competitively. Experimental evidence has suggested that fibrinogen binding to the RGD-type integrin alphaIIbbeta3 occurs exclusively through the synergistic gamma(400-411) sequence, thus questioning the functional role of the RGD recognition site. Here we have investigated the respective role of the fibrinogen gamma(400-411) sequence and the RGD motif in the molecular events leading to ligand-induced alphaIIbbeta3-dependent Chinese hamster ovary (CHO) cell or platelet spreading, by using intact fibrinogen and well characterized plasmin-generated fibrinogen fragments containing either the RGD motif (fragment C) or the gamma(400-411) sequence (fragment D), and CHO cells expressing resting wild type (alphaIIbbeta3wt), constitutively active (alphaIIbbeta3T562N), or non-functional (alphaIIbbeta3D119Y) receptors. Our data provide evidence that the gamma(400-411) site by itself is able to initiate alphaIIbbeta3 clustering and recruitment of intracellular proteins to early focal complexes, mediating cell attachment, FAK phosphorylation, and Rac1 activation, while the RGD motif subsequently acts as a molecular switch on the beta3 subunit to trigger cell spreading. More importantly, we show that the premier functional role of the RGD site is not to reinforce cell attachment but, rather, to imprint a conformational change on the beta3 subunit leading to maximal RhoA activation and actin cytoskeleton organization in CHO cells as well as in platelets. Finally, alphaIIbbeta3-dependent RhoA stimulation and cell spreading, but not cell attachment, are Src-dependent and phosphoinositide 3-kinase-independent and are inhibited by the Src antagonist PP2.
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Affiliation(s)
- Alexandre Salsmann
- Laboratoire de Biologie et Physiologie Intégrée (CNRS/GDRE-ITI), Université du Luxembourg, 162A Avenue de la Faïencerie, L-1511 Luxembourg, Grand-Duchy of Luxembourg
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