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Pang X, He X, Qiu Z, Zhang H, Xie R, Liu Z, Gu Y, Zhao N, Xiang Q, Cui Y. Targeting integrin pathways: mechanisms and advances in therapy. Signal Transduct Target Ther 2023; 8:1. [PMID: 36588107 PMCID: PMC9805914 DOI: 10.1038/s41392-022-01259-6] [Citation(s) in RCA: 86] [Impact Index Per Article: 86.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 11/14/2022] [Accepted: 11/21/2022] [Indexed: 01/03/2023] Open
Abstract
Integrins are considered the main cell-adhesion transmembrane receptors that play multifaceted roles as extracellular matrix (ECM)-cytoskeletal linkers and transducers in biochemical and mechanical signals between cells and their environment in a wide range of states in health and diseases. Integrin functions are dependable on a delicate balance between active and inactive status via multiple mechanisms, including protein-protein interactions, conformational changes, and trafficking. Due to their exposure on the cell surface and sensitivity to the molecular blockade, integrins have been investigated as pharmacological targets for nearly 40 years, but given the complexity of integrins and sometimes opposite characteristics, targeting integrin therapeutics has been a challenge. To date, only seven drugs targeting integrins have been successfully marketed, including abciximab, eptifibatide, tirofiban, natalizumab, vedolizumab, lifitegrast, and carotegrast. Currently, there are approximately 90 kinds of integrin-based therapeutic drugs or imaging agents in clinical studies, including small molecules, antibodies, synthetic mimic peptides, antibody-drug conjugates (ADCs), chimeric antigen receptor (CAR) T-cell therapy, imaging agents, etc. A serious lesson from past integrin drug discovery and research efforts is that successes rely on both a deep understanding of integrin-regulatory mechanisms and unmet clinical needs. Herein, we provide a systematic and complete review of all integrin family members and integrin-mediated downstream signal transduction to highlight ongoing efforts to develop new therapies/diagnoses from bench to clinic. In addition, we further discuss the trend of drug development, how to improve the success rate of clinical trials targeting integrin therapies, and the key points for clinical research, basic research, and translational research.
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Affiliation(s)
- Xiaocong Pang
- grid.411472.50000 0004 1764 1621Department of Pharmacy, Peking University First Hospital, Xishiku Street, Xicheng District, 100034 Beijing, China ,grid.411472.50000 0004 1764 1621Institute of Clinical Pharmacology, Peking University First Hospital, Xueyuan Road 38, Haidian District, 100191 Beijing, China
| | - Xu He
- grid.411472.50000 0004 1764 1621Department of Pharmacy, Peking University First Hospital, Xishiku Street, Xicheng District, 100034 Beijing, China ,grid.411472.50000 0004 1764 1621Institute of Clinical Pharmacology, Peking University First Hospital, Xueyuan Road 38, Haidian District, 100191 Beijing, China
| | - Zhiwei Qiu
- grid.411472.50000 0004 1764 1621Department of Pharmacy, Peking University First Hospital, Xishiku Street, Xicheng District, 100034 Beijing, China ,grid.411472.50000 0004 1764 1621Institute of Clinical Pharmacology, Peking University First Hospital, Xueyuan Road 38, Haidian District, 100191 Beijing, China
| | - Hanxu Zhang
- grid.411472.50000 0004 1764 1621Department of Pharmacy, Peking University First Hospital, Xishiku Street, Xicheng District, 100034 Beijing, China ,grid.411472.50000 0004 1764 1621Institute of Clinical Pharmacology, Peking University First Hospital, Xueyuan Road 38, Haidian District, 100191 Beijing, China
| | - Ran Xie
- grid.411472.50000 0004 1764 1621Department of Pharmacy, Peking University First Hospital, Xishiku Street, Xicheng District, 100034 Beijing, China ,grid.411472.50000 0004 1764 1621Institute of Clinical Pharmacology, Peking University First Hospital, Xueyuan Road 38, Haidian District, 100191 Beijing, China
| | - Zhiyan Liu
- grid.411472.50000 0004 1764 1621Department of Pharmacy, Peking University First Hospital, Xishiku Street, Xicheng District, 100034 Beijing, China ,grid.411472.50000 0004 1764 1621Institute of Clinical Pharmacology, Peking University First Hospital, Xueyuan Road 38, Haidian District, 100191 Beijing, China
| | - Yanlun Gu
- grid.411472.50000 0004 1764 1621Department of Pharmacy, Peking University First Hospital, Xishiku Street, Xicheng District, 100034 Beijing, China ,grid.411472.50000 0004 1764 1621Institute of Clinical Pharmacology, Peking University First Hospital, Xueyuan Road 38, Haidian District, 100191 Beijing, China
| | - Nan Zhao
- grid.411472.50000 0004 1764 1621Department of Pharmacy, Peking University First Hospital, Xishiku Street, Xicheng District, 100034 Beijing, China ,grid.411472.50000 0004 1764 1621Institute of Clinical Pharmacology, Peking University First Hospital, Xueyuan Road 38, Haidian District, 100191 Beijing, China
| | - Qian Xiang
- Department of Pharmacy, Peking University First Hospital, Xishiku Street, Xicheng District, 100034, Beijing, China. .,Institute of Clinical Pharmacology, Peking University First Hospital, Xueyuan Road 38, Haidian District, 100191, Beijing, China.
| | - Yimin Cui
- Department of Pharmacy, Peking University First Hospital, Xishiku Street, Xicheng District, 100034, Beijing, China. .,Institute of Clinical Pharmacology, Peking University First Hospital, Xueyuan Road 38, Haidian District, 100191, Beijing, China.
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Nagy M, van der Meijden PEJ, Glunz J, Schurgers L, Lutgens E, ten Cate H, Heitmeier S, Spronk HMH. Integrating Mechanisms in Thrombotic Peripheral Arterial Disease. Pharmaceuticals (Basel) 2022; 15:1428. [PMID: 36422558 PMCID: PMC9695058 DOI: 10.3390/ph15111428] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 11/12/2022] [Accepted: 11/14/2022] [Indexed: 11/10/2023] Open
Abstract
Peripheral arterial disease (PAD), a manifestation of systemic atherosclerosis, is underdiagnosed in the general population. Despite the extensive research performed to unravel its pathophysiology, inadequate knowledge exists, thus preventing the development of new treatments. This review aims to highlight the essential elements of atherosclerosis contributing to the pathophysiology of PAD. Furthermore, emphasis will be placed on the role of thrombo-inflammation, with particular focus on platelet and coagulation activation as well as cell-cell interactions. Additional insight will be then discussed to reveal the contribution of hypercoagulability to the development of vascular diseases such as PAD. Lastly, the current antithrombotic treatments will be discussed, and light will be shed on promising new targets aiming to aid the development of new treatments.
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Affiliation(s)
- Magdolna Nagy
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, 6229 ER Maastricht, The Netherlands
| | - Paola E. J. van der Meijden
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, 6229 ER Maastricht, The Netherlands
- Thrombosis Expertise Center, Heart and Vascular Center, Maastricht University Medical Center+, 6229 HX Maastricht, The Netherlands
| | - Julia Glunz
- Cardiovascular Research, Bayer AG, 42117 Wuppertal, Germany
| | - Leon Schurgers
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, 6229 ER Maastricht, The Netherlands
| | - Esther Lutgens
- German Centre for Cardiovascular Research (DZHK), Partner Site Munich Heart Alliance, 10785 Munich, Germany
- Institute for Cardiovascular Prevention (IPEK), Ludwig Maximilian’s University, 80539 Munich, Germany
- Experimental Cardiovascular Immunology Laboratory, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN 55902, USA
| | - Hugo ten Cate
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, 6229 ER Maastricht, The Netherlands
- Thrombosis Expertise Center, Heart and Vascular Center, Maastricht University Medical Center+, 6229 HX Maastricht, The Netherlands
- Department of Internal Medicine, Maastricht University Medical Center+, 6229 HX Maastricht, The Netherlands
- Center for Thrombosis and Hemostasis, Gutenberg University Mainz, 55122 Mainz, Germany
| | | | - Henri M. H. Spronk
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, 6229 ER Maastricht, The Netherlands
- Thrombosis Expertise Center, Heart and Vascular Center, Maastricht University Medical Center+, 6229 HX Maastricht, The Netherlands
- Department of Internal Medicine, Maastricht University Medical Center+, 6229 HX Maastricht, The Netherlands
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3
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Dahiya N, Atreya CD. MiR-181a Reduces Platelet Activation via the Inhibition of Endogenous RAP1B. Microrna 2021; 9:240-246. [PMID: 31738148 PMCID: PMC7366005 DOI: 10.2174/2211536608666191026120515] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 08/21/2019] [Accepted: 09/20/2019] [Indexed: 12/18/2022]
Abstract
Aim Since RAP1B is critical for platelet functions, including hemostasis, this study was conducted to identify RAP1B regulating microRNAs (miRNAs) in ex vivo stored platelets. Background Previous studies with platelets identified factors affecting RAP1B activity but regulatory miRNAs that affect RAP1B protein expression have not been reported. Objective To understand the functional significance of miRNA mediated regulation of RAP1B in stored platelets, using microRNA, miR-181a as an example. Methods A Tagged RNA Affinity approach (MS2-TRAP) was employed to identify miRNAs that bound to the 3` untranslated region (3`UTR) of the RAP1B mRNA in HeLa cells as an assay system. And subsequently, the mRNA 3’UTR:miRNA interactions were verified in platelets through the ectopic expression of miR-181a mimic and appropriate controls. The interaction of such miRNAs with RAP1B mRNA was also validated by qRT-PCR and Western analysis. Results Sixty-two miRNAs from MS2 assay were then compared with already known 171 platelet abundant miRNAs to identify a common set of miRNAs. This analysis yielded six miRNAs (miR-30e, miR-155, miR-181a, miR-206, miR-208a and miR-454), which are also predicted to target RAP1B mRNA. From this pool, miR-181a was selected for further study since RAP1B harbors two binding sites for miR-181a in its 3′UTR. Ectopic expression of miR-181a mimic in platelets resulted in lowering the endogenous RAP1B at both mRNA and protein levels. Further, miR-181a ectopic expression reduced the surface expression of the platelet activation marker, P-selectin. Conclusion MicroRNA-181a can target RAP1B and this interaction has the potential to regulate platelet activation during storage.
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Affiliation(s)
- Neetu Dahiya
- Laboratory of Cellular Hematology, Division of Blood Components and Devices, Center for Biologics Evaluation and Research, US Food and Drug Administration, Silver Spring, MD 20993, United States
| | - Chintamani D Atreya
- Laboratory of Cellular Hematology, Division of Blood Components and Devices, Center for Biologics Evaluation and Research, US Food and Drug Administration, Silver Spring, MD 20993, United States
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Choudry FA, Bagger FO, Macaulay IC, Farrow S, Burden F, Kempster C, McKinney H, Olsen LR, Huang N, Downes K, Voet T, Uppal R, Martin JF, Mathur A, Ouwehand WH, Laurenti E, Teichmann SA, Frontini M. Transcriptional characterization of human megakaryocyte polyploidization and lineage commitment. J Thromb Haemost 2021; 19:1236-1249. [PMID: 33587817 DOI: 10.1111/jth.15271] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 02/09/2021] [Accepted: 02/12/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND Megakaryocytes (MKs) originate from cells immuno-phenotypically indistinguishable from hematopoietic stem cells (HSCs), bypassing intermediate progenitors. They mature within the adult bone marrow and release platelets into the circulation. Until now, there have been no transcriptional studies of primary human bone marrow MKs. OBJECTIVES To characterize MKs and HSCs from human bone marrow using single-cell RNA sequencing, to investigate MK lineage commitment, maturation steps, and thrombopoiesis. RESULTS We show that MKs at different levels of polyploidization exhibit distinct transcriptional states. Although high levels of platelet-specific gene expression occur in the lower ploidy classes, as polyploidization increases, gene expression is redirected toward translation and posttranslational processing transcriptional programs, in preparation for thrombopoiesis. Our findings are in keeping with studies of MK ultrastructure and supersede evidence generated using in vitro cultured MKs. Additionally, by analyzing transcriptional signatures of a single HSC, we identify two MK-biased HSC subpopulations exhibiting unique differentiation kinetics. We show that human bone marrow MKs originate from these HSC subpopulations, supporting the notion that they display priming for MK differentiation. Finally, to investigate transcriptional changes in MKs associated with stress thrombopoiesis, we analyzed bone marrow MKs from individuals with recent myocardial infarction and found a specific gene expression signature. Our data support the modulation of MK differentiation in this thrombotic state. CONCLUSIONS Here, we use single-cell sequencing for the first time to characterize the human bone marrow MK transcriptome at different levels of polyploidization and investigate their differentiation from the HSC.
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Affiliation(s)
- Fizzah A Choudry
- Department of Hematology, University of Cambridge, Cambridge, UK
- Barts Heart Centre, Barts Health NHS Trust, London, UK
- Centre for Cardiovascular Medicine and Devices, Queen Mary University of London, London, UK
| | - Frederik O Bagger
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Cambridge, UK
- The Wellcome Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK
- Centre for Genomic Medicine, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Iain C Macaulay
- The Wellcome Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK
| | - Samantha Farrow
- Department of Hematology, University of Cambridge, Cambridge, UK
| | - Frances Burden
- Department of Hematology, University of Cambridge, Cambridge, UK
| | - Carly Kempster
- Department of Hematology, University of Cambridge, Cambridge, UK
| | - Harriet McKinney
- Department of Hematology, University of Cambridge, Cambridge, UK
| | - Lars R Olsen
- Centre for Genomic Medicine, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Department of Health Technology, Technical University of Denmark, Lyngby, Denmark
| | - Ni Huang
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Cambridge, UK
- The Wellcome Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK
| | - Kate Downes
- Department of Hematology, University of Cambridge, Cambridge, UK
| | - Thierry Voet
- The Wellcome Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK
| | - Rakesh Uppal
- Barts Heart Centre, Barts Health NHS Trust, London, UK
- Centre for Cardiovascular Medicine and Devices, Queen Mary University of London, London, UK
| | - John F Martin
- Division of Medicine, University College London, London, UK
| | - Anthony Mathur
- Barts Heart Centre, Barts Health NHS Trust, London, UK
- Centre for Cardiovascular Medicine and Devices, Queen Mary University of London, London, UK
| | - Willem H Ouwehand
- Department of Hematology, University of Cambridge, Cambridge, UK
- The Wellcome Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK
- BHF Centre of Excellence, Division of Cardiovascular Medicine, Cambridge University Hospitals, Cambridge, UK
| | - Elisa Laurenti
- Department of Hematology, University of Cambridge, Cambridge, UK
| | - Sarah A Teichmann
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Cambridge, UK
- The Wellcome Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK
| | - Mattia Frontini
- Department of Hematology, University of Cambridge, Cambridge, UK
- BHF Centre of Excellence, Division of Cardiovascular Medicine, Cambridge University Hospitals, Cambridge, UK
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Zhou M, Hu H, Han Y, Li J, Zhang Y, Tang S, Yuan Y, Zhang X. Long non-coding RNA 01126 promotes periodontitis pathogenesis of human periodontal ligament cells via miR-518a-5p/HIF-1α/MAPK pathway. Cell Prolif 2020; 54:e12957. [PMID: 33231338 PMCID: PMC7791173 DOI: 10.1111/cpr.12957] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 10/10/2020] [Accepted: 10/23/2020] [Indexed: 12/12/2022] Open
Abstract
Background Periodontitis is a prevalent oral inflammatory disease, which can cause periodontal ligament to a local hypoxia environment. However, the mechanism of hypoxia associated long non‐coding RNAs (lncRNAs) involved in periodontitis is still largely unknown. Methods Microarray was performed to detect the expression patterns of lncRNAs in 3 pairs of gingival tissues from patients with periodontitis and healthy controls. The expression of lncRNA 01126 (LINC01126), miR‐518a‐5p and hypoxia‐inducible factor‐1α (HIF‐1α) in periodontal tissues and in human periodontal ligament cells (hPDLCs) under hypoxia was measured by quantitative real‐time polymerase chain reaction or western blot. Fluorescence in situ hybridization and cell fraction assay were performed to determine the subcellular localization of LINC01126 and miR‐518a‐5p. Overexpression or knockdown of LINC01126 or HIF‐1α was used to confirm their biological roles in hPDLCs. MTT assays were performed to evaluate hPDLCs proliferation ability. Flow cytometry was used to detect apoptosis. ELISA was used to measure the expression levels of interleukin (IL)‐1β, IL‐6, IL‐8 and TNF‐α. Dual‐luciferase reporter assays were performed to assess the binding of miR‐518a‐5p to LINC01126 and HIF‐1α. RNA immunoprecipitation assay was used to identify whether LINC01126 and miR‐518a‐5p were significantly enriched in AGO‐containing micro‐ribonucleoprotein complexes. Results We selected LINC01126, which was the most highly expressed lncRNA, to further verify its functions in periodontitis‐induced hypoxia. The expression of LINC01126 was increased in periodontal tissues. In vitro experiment demonstrated that LINC01126 suppressed proliferation, promoted apoptosis and inflammation of hPDLCs under hypoxia via sponging miR‐518a‐5p. Moreover, we identified HIF‐1α acted as a direct target of miR‐518a‐5p in hPDLCs and LINC01126 promoted periodontitis pathogenesis by regulating the miR‐518a‐5p/HIF‐1α/MAPK pathway. Conclusion LINC01126 promotes periodontitis pathogenesis of hPDLCs via miR‐518a‐5p/HIF‐1α/MAPK pathway, providing a possible clue for LINC01126‐based periodontal therapeutic approaches.
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Affiliation(s)
- Mi Zhou
- College of Stomatology, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing, China.,Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing, China
| | - Hui Hu
- College of Stomatology, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing, China.,Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing, China
| | - Yineng Han
- Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China
| | - Jie Li
- Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing, China.,Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing, China
| | - Yang Zhang
- College of Stomatology, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing, China
| | - Song Tang
- College of Stomatology, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing, China
| | - Yu Yuan
- College of Stomatology, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing, China
| | - Xiaonan Zhang
- College of Stomatology, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing, China.,Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing, China
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6
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Canault M, Alessi MC. RasGRP2 Structure, Function and Genetic Variants in Platelet Pathophysiology. Int J Mol Sci 2020; 21:E1075. [PMID: 32041177 PMCID: PMC7037602 DOI: 10.3390/ijms21031075] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/31/2020] [Accepted: 02/03/2020] [Indexed: 12/18/2022] Open
Abstract
RasGRP2 is calcium and diacylglycerol-regulated guanine nucleotide exchange factor I that activates Rap1, which is an essential signaling-knot in "inside-out" αIIbβ3 integrin activation in platelets. Inherited platelet function disorder caused by variants of RASGRP2 represents a new congenital bleeding disorder referred to as platelet-type bleeding disorder-18 (BDPLT18). We review here the structure of RasGRP2 and its functions in the pathophysiology of platelets and of the other cellular types that express it. We will also examine the different pathogenic variants reported so far as well as strategies for the diagnosis and management of patients with BDPLT18.
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Affiliation(s)
- Matthias Canault
- Aix Marseille University, INSERM, INRAE, C2VN, 13005 Marseille, France
| | - Marie-Christine Alessi
- Aix Marseille University, INSERM, INRAE, C2VN, 13005 Marseille, France
- Hematology laboratory, APHM, CHU Timone, 13005 Marseille, France
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7
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Guidetti GF, Torti M, Canobbio I. Focal Adhesion Kinases in Platelet Function and Thrombosis. Arterioscler Thromb Vasc Biol 2019; 39:857-868. [DOI: 10.1161/atvbaha.118.311787] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The focal adhesion kinase family includes 2 homolog members, FAK and Pyk2 (proline-rich tyrosine kinase 2), primarily known for their roles in nucleated cells as regulators of cytoskeletal dynamics and cell adhesion. FAK and Pyk2 are also expressed in megakaryocytes and platelets and are activated by soluble agonists and on adhesion to the subendothelial matrix. Despite high sequence homology and similar molecular organization, FAK and Pyk2 play different roles in platelet function. Whereas FAK serves mostly as a traditional focal adhesion kinase activated downstream of integrins, Pyk2 coordinates multiple signals from different receptors. FAK, but not Pyk2, is involved in megakaryocyte maturation and platelet production. In circulating platelets, FAK is recruited by integrin αIIbβ3 to regulate hemostasis, whereas it plays minimal roles in thrombosis. By contrast, Pyk2 is implicated in platelet activation and is an important regulator of thrombosis. The direct activation of Pyk2 by calcium ions provides a connection between GPCRs (G-protein coupled receptors) and Src family kinases. In this review, we provide the comprehensive overview of >20 years of investigations on the role and regulation of focal adhesion kinases in blood platelets, highlighting common and distinctive features of FAK and Pyk2 in hemostasis and thrombosis.
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Affiliation(s)
| | - Mauro Torti
- From the Department of Biology and Biotechnology, University of Pavia, Italy
| | - Ilaria Canobbio
- From the Department of Biology and Biotechnology, University of Pavia, Italy
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8
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Stefanini L, Bergmeier W. RAP GTPases and platelet integrin signaling. Platelets 2018; 30:41-47. [PMID: 29863951 PMCID: PMC6312509 DOI: 10.1080/09537104.2018.1476681] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 04/26/2018] [Accepted: 04/27/2018] [Indexed: 12/31/2022]
Abstract
Platelets are highly specialized cells that continuously patrol the vasculature to ensure its integrity (hemostasis). At sites of vascular injury, they are able to respond to trace amounts of agonists and to rapidly transition from an anti-adhesive/patrolling to an adhesive state (integrin inside-out activation) required for hemostatic plug formation. Pathological conditions that disturb the balance in the underlying signaling processes can lead to unwanted platelet activation (thrombosis) or to an increased bleeding risk. The small GTPases of the RAP subfamily, highly expressed in platelets, are critical regulators of cell adhesion, cytoskeleton remodeling, and MAP kinase signaling. Studies by our group and others demonstrate that RAP GTPases, in particular RAP1A and RAP1B, are the key molecular switches that turn on platelet activation/adhesiveness at sites of injury. In this review, we will summarize major findings on the role of RAP GTPases in platelet biology with a focus on the signaling pathways leading to the conversion of integrins to a high-affinity state.
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Affiliation(s)
- Lucia Stefanini
- Department of Internal Medicine and Medical Specialties, Sapienza University of Rome, Rome, Italy
| | - Wolfgang Bergmeier
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill (NC), USA
- McAllister Heart Institute, University of North Carolina at Chapel Hill (NC), USA
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9
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Zarà M, Canobbio I, Visconte C, Di Nunzio G, Torti M, Guidetti G. Novel pharmacological inhibitors demonstrate the role of the tyrosine kinase Pyk2 in adhesion and aggregation of human platelets. Thromb Haemost 2017; 116:904-917. [DOI: 10.1160/th16-01-0067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 06/13/2016] [Indexed: 11/05/2022]
Abstract
SummaryPyk2 is a Ca2+-regulated kinase predominantly expressed in neuronal and in haematopoietic cells. Previous studies on Pyk2-null mice have demonstrated that Pyk2 plays a crucial role in platelet activation and thrombus formation, thus representing a possible target for antithrombotic therapy. Very limited information is available about the role of Pyk2 in human platelets, mainly because of the lack of specific pharmacological inhibitors. In this work, we have tested two novel Pyk2 inhibitors, PF-4594755 and PF-4520440, to validate their specificity and to investigate their ability to modulate platelet activation. Both molecules were able to efficiently block Pyk2 activity in human and mouse platelets stimulated with thrombin or with the Ca2+-ionophore. In wild-type murine platelets, PF-4594755 and PF-4520440 reduced thrombin-induced aggregation to the level observed in Pyk2 knockout platelets, but did not affect aggregation induced by GPVI stimulation. Importantly, neither compounds affected the residual thrombin-induced aggregation of Pyk2-null platelets, thus excluding possible off-target effects. In human platelets, PF-4594755 and PF-4520440 significantly reduced aggregation stimulated by thrombin, but not by the GPVI agonist convulxin. Both inhibitors reduced platelet adhesion on fibrinogen and prevented Akt phosphorylation in adherent cells, indicating that Pyk2 regulates PI3K and cell spreading downstream of integrins in human platelets. Finally, the Pyk2 inhibitors significantly inhibited thrombus formation upon blood perfusion on immobilized collagen under arterial flow rate. These results demonstrate that PF-4594755 and PF-4520440 are specific inhibitors of Pyk2 in intact platelets and allowed to reliably document that this kinase plays a relevant role in human platelet activation.Supplementary Material to this article is available online at www.thrombosis-online.com.
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10
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Nygaard G, Herfindal L, Asrud KS, Bjørnstad R, Kopperud RK, Oveland E, Berven FS, Myhren L, Hoivik EA, Lunde THF, Bakke M, Døskeland SO, Selheim F. Epac1-deficient mice have bleeding phenotype and thrombocytes with decreased GPIbβ expression. Sci Rep 2017; 7:8725. [PMID: 28821815 PMCID: PMC5562764 DOI: 10.1038/s41598-017-08975-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 07/17/2017] [Indexed: 11/16/2022] Open
Abstract
Epac1 (Exchange protein directly activated by cAMP 1) limits fluid loss from the circulation by tightening the endothelial barrier. We show here that Epac1-/- mice, but not Epac2-/- mice, have prolonged bleeding time, suggesting that Epac1 may limit fluid loss also by restraining bleeding. The Epac1-/- mice had deficient in vitro secondary hemostasis. Quantitative comprehensive proteomics analysis revealed that Epac1-/- mouse platelets (thrombocytes) had unbalanced expression of key components of the glycoprotein Ib-IX-V (GPIb-IX-V) complex, with decrease of GP1bβ and no change of GP1bα. This complex is critical for platelet adhesion under arterial shear conditions. Furthermore, Epac1-/- mice have reduced levels of plasma coagulation factors and fibrinogen, increased size of circulating platelets, increased megakaryocytes (the GP1bβ level was decreased also in Epac1-/- bone marrow) and higher abundance of reticulated platelets. Viscoelastic measurement of clotting function revealed Epac1-/- mice with a dysfunction in the clotting process, which corresponds to reduced plasma levels of coagulation factors like factor XIII and fibrinogen. We propose that the observed platelet phenotype is due to deficient Epac1 activity during megakaryopoiesis and thrombopoiesis, and that the defects in blood clotting for Epac1-/- is connected to secondary hemostasis.
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Affiliation(s)
- Gyrid Nygaard
- Department of Biomedicine, University of Bergen, Bergen, Norway
- The Proteomics Unit at the University of Bergen, Bergen, Norway
| | - Lars Herfindal
- Centre for Pharmacy, Department of Clinical Science, University of Bergen, Bergen, Norway
| | | | - Ronja Bjørnstad
- Centre for Pharmacy, Department of Clinical Science, University of Bergen, Bergen, Norway
- Hospital Pharmacies Enterprise, Western Norway, Bergen, Norway
| | | | - Eystein Oveland
- The Proteomics Unit at the University of Bergen, Bergen, Norway
| | - Frode S Berven
- Department of Biomedicine, University of Bergen, Bergen, Norway
- The Proteomics Unit at the University of Bergen, Bergen, Norway
| | - Lene Myhren
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Erling A Hoivik
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Turid Helen Felli Lunde
- Department of Immunology and Transfusion Medicine, Haukeland University Hospital, Bergen, Norway
| | - Marit Bakke
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | | | - Frode Selheim
- Department of Biomedicine, University of Bergen, Bergen, Norway.
- The Proteomics Unit at the University of Bergen, Bergen, Norway.
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11
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RAP1B, a DVL2 binding protein, activates Wnt/beta-catenin signaling in esophageal squamous cell carcinoma. Gene 2017; 611:15-20. [PMID: 28119087 DOI: 10.1016/j.gene.2017.01.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 01/15/2017] [Accepted: 01/20/2017] [Indexed: 11/22/2022]
Abstract
RAP1B is a small GTPase, which regulates multiple cellular processes. Up-regulation of RAP1B has been observed in several cancer types. Although previous study has shown that miR-518 inhibited the proliferation and invasion of esophageal squamous cell carcinoma (ESCC) cells possibly by targeting RAP1B, the expression pattern and the functions of RAP1B in ESCC are not fully understood. Here, we have fund that the expression of RAP1B was up-regulated in ESCC clinical samples. Gain-of-function and loss-of-function assays demonstrated that RAP1B promoted the growth, migration and metastasis of the ESCC cells. Moreover, the mechanism study showed that RAP1B interacted with DVL2, an important upstream regulator for beta-catenin/TCF signaling, and activated beta-catenin/TCF signaling. Taken together, our study demonstrated the oncogenic roles of RAP1B in ESCC, and suggested that RAP1B might be a therapeutic target.
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12
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The cyclic AMP phosphodiesterase 4D5 (PDE4D5)/receptor for activated C-kinase 1 (RACK1) signalling complex as a sensor of the extracellular nano-environment. Cell Signal 2017; 35:282-289. [PMID: 28069443 DOI: 10.1016/j.cellsig.2017.01.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 01/04/2017] [Indexed: 01/15/2023]
Abstract
The cyclic AMP and protein kinase C (PKC) signalling pathways regulate a wide range of cellular processes that require tight control, including cell proliferation and differentiation, metabolism and inflammation. The identification of a protein complex formed by receptor for activated C kinase 1 (RACK1), a scaffold protein for protein kinase C (PKC), and the cyclic AMP-specific phosphodiesterase, PDE4D5, demonstrates a potential mechanism for crosstalk between these two signalling routes. Indeed, RACK1-bound PDE4D5 is activated by PKCα, providing a route through which the PKC pathway can control cellular cyclic AMP levels. Although RACK1 does not appear to affect the intracellular localisation of PDE4D5, it does afford structural stability, providing protection against denaturation, and increases the susceptibility of PDE4D5 to inhibition by cyclic AMP-elevating pharmaceuticals, such as rolipram. In addition, RACK1 can recruit PDE4D5 and PKC to intracellular protein complexes that control diverse cellular functions, including activated G protein-coupled receptors (GPCRs) and integrins clustered at focal adhesions. Through its ability to regulate local cyclic AMP levels in the vicinity of these multimeric receptor complexes, the RACK1/PDE4D5 signalling unit therefore has the potential to modify the quality of incoming signals from diverse extracellular cues, ranging from neurotransmitters and hormones to nanometric topology. Indeed, PDE4D5 and RACK1 have been found to form a tertiary complex with integrin-activated focal adhesion kinase (FAK), which localises to cellular focal adhesion sites. This supports PDE4D5 and RACK1 as potential regulators of cell adhesion, spreading and migration through the non-classical exchange protein activated by cyclic AMP (EPAC1)/Rap1 signalling route.
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13
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Stefanini L, Bergmeier W. RAP1-GTPase signaling and platelet function. J Mol Med (Berl) 2015; 94:13-9. [PMID: 26423530 DOI: 10.1007/s00109-015-1346-3] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 09/10/2015] [Accepted: 09/17/2015] [Indexed: 10/23/2022]
Abstract
Platelets are critical for hemostasis, i.e., the body's ability to prevent blood loss at sites of vascular injury. They patrol the vasculature in a quiescent, non-adhesive state for approximately 10 days, after which they are removed from circulation by phagocytic cells of the reticulo-endothelial system. At sites of vascular injury, they promptly shift to an activated, adhesive state required for the formation of a hemostatic plug. The small GTPase RAP1 is a critical regulator of platelet adhesiveness. Our recent studies demonstrate that the antagonistic balance between the RAP1 regulators, CalDAG-GEFI and RASA3, is critical for the modulation of platelet adhesiveness, both in circulation and at sites of vascular injury. The RAP1 activator CalDAG-GEFI responds to small changes in the cytoplasmic calcium concentration and thus provides sensitivity and speed to the activation response, essential for efficient platelet adhesion under conditions of hemodynamic shear stress. The RAP1 inhibitor RASA3 ensures that circulating platelets remain quiescent by restraining CalDAG-GEFI-dependent RAP1 activation. Upon cellular stimulation, it is turned off by P2Y12 signaling to enable sustained RAP1 activation, required for the formation of a stable hemostatic plug. This review will summarize important studies that elucidated the signaling pathways that control RAP1 activation in platelets.
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Affiliation(s)
- Lucia Stefanini
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK
| | - Wolfgang Bergmeier
- Department of Biochemistry and Biophysics, McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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14
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Lever RA, Hussain A, Sun BB, Sage SO, Harper AGS. Conventional protein kinase C isoforms differentially regulate ADP- and thrombin-evoked Ca²⁺ signalling in human platelets. Cell Calcium 2015; 58:577-88. [PMID: 26434503 DOI: 10.1016/j.ceca.2015.09.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 09/22/2015] [Accepted: 09/23/2015] [Indexed: 11/15/2022]
Abstract
Rises in cytosolic Ca(2+) concentration ([Ca(2+)]cyt) are central in platelet activation, yet many aspects of the underlying mechanisms are poorly understood. Most studies examine how experimental manipulations affect agonist-evoked rises in [Ca(2+)]cyt, but these only monitor the net effect of manipulations on the processes controlling [Ca(2+)]cyt (Ca(2+) buffering, sequestration, release, entry and removal), and cannot resolve the source of the Ca(2+) or the transporters or channels affected. To investigate the effects of protein kinase C (PKC) on platelet Ca(2+) signalling, we here monitor Ca(2+) flux around the platelet by measuring net Ca(2+) fluxes to or from the extracellular space and the intracellular Ca(2+) stores, which act as the major sources and sinks for Ca(2+) influx into and efflux from the cytosol, as well as monitoring the cytosolic Na(+) concentration ([Na(+)]cyt), which influences platelet Ca(2+) fluxes via Na(+)/Ca(2+) exchange. The intracellular store Ca(2+) concentration ([Ca(2+)]st) was monitored using Fluo-5N, the extracellular Ca(2+) concentration ([Ca(2+)]ext) was monitored using Fluo-4 whilst [Ca(2+)]cyt and [Na(+)]cyt were monitored using Fura-2 and SFBI, respectively. PKC inhibition using Ro-31-8220 or bisindolylmaleimide I potentiated ADP- and thrombin-evoked rises in [Ca(2+)]cyt in the absence of extracellular Ca(2+). PKC inhibition potentiated ADP-evoked but reduced thrombin-evoked intracellular Ca(2+) release and Ca(2+) removal into the extracellular medium. SERCA inhibition using thapsigargin and 2,5-di(tert-butyl) l,4-benzohydroquinone abolished the effect of PKC inhibitors on ADP-evoked changes in [Ca(2+)]cyt but only reduced the effect on thrombin-evoked responses. Thrombin evokes substantial rises in [Na(+)]cyt which would be expected to reduce Ca(2+) removal via the Na(+)/Ca(2+) exchanger (NCX). Thrombin-evoked rises in [Na(+)]cyt were potentiated by PKC inhibition, an effect which was not due to altered changes in non-selective cation permeability of the plasma membrane as assessed by Mn(2+) quench of Fura-2 fluorescence. PKC inhibition was without effect on thrombin-evoked rises in [Ca(2+)]cyt following SERCA inhibition and either removal of extracellular Na(+) or inhibition of Na(+)/K(+)-ATPase activity by removal of extracellular K(+) or treatment with digoxin. These data suggest that PKC limits ADP-evoked rises in [Ca(2+)]cyt by acceleration of SERCA activity, whilst rises in [Ca(2+)]cyt evoked by the stronger platelet activator thrombin are limited by PKC through acceleration of both SERCA and Na(+)/K(+)-ATPase activity, with the latter limiting the effect of thrombin on rises in [Na(+)]cyt and so forward mode NCX activity. The use of selective PKC inhibitors indicated that conventional and not novel PKC isoforms are responsible for the inhibition of agonist-evoked Ca(2+) signalling.
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Affiliation(s)
- Robert A Lever
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom
| | - Azhar Hussain
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom
| | - Benjamin B Sun
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom
| | - Stewart O Sage
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom
| | - Alan G S Harper
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom; Institute for Science and Technology in Medicine, Keele University, Guy Hilton Research Centre, Thornburrow Drive, Hartshill, Stoke-on-Trent ST4 7QB, United Kingdom.
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15
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Guidetti GF, Canobbio I, Torti M. PI3K/Akt in platelet integrin signaling and implications in thrombosis. Adv Biol Regul 2015; 59:36-52. [PMID: 26159296 DOI: 10.1016/j.jbior.2015.06.001] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 06/04/2015] [Accepted: 06/04/2015] [Indexed: 01/09/2023]
Abstract
Blood platelets are anucleated circulating cells that play a critical role in hemostasis and are also implicated in arterial thrombosis, a major cause of death worldwide. The biological function of platelets strongly relies in their reactiveness to a variety of extracellular agonists that regulate their adhesion to extracellular matrix at the site of vascular injury and their ability to form rapidly growing cell aggregates. Among the membrane receptors expressed on the cell surface, integrins are crucial for both platelet activation, adhesion and aggregation. Integrin affinity for specific ligands is regulated by intracellular signaling pathways activated in stimulated platelets, and, once engaged, integrins themselves generate and propagate signals inside the cells to reinforce and consolidate platelet response and thrombus formation. Phosphatidylinositol 3-Kinases (PI3Ks) have emerged as crucial players in platelet activation, and they are directly implicated in the regulation of integrin function. This review will discuss the contribution of PI3Ks in platelet integrin signaling, focusing on the role of specific members of class I PI3Ks and their downstream effector Akt on both integrin inside-out and outside-in signaling. The contribution of the PI3K/Akt pathways stimulated by integrin engagement and platelet activation in thrombus formation and stabilization will also be discussed in order to highlight the possibility to target these enzymes in effective anti-thrombotic therapeutic strategies.
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Affiliation(s)
- Gianni F Guidetti
- Department of Biology and Biotechnology, Laboratories of Biochemistry, University of Pavia, Pavia, Italy
| | - Ilaria Canobbio
- Department of Biology and Biotechnology, Laboratories of Biochemistry, University of Pavia, Pavia, Italy
| | - Mauro Torti
- Department of Biology and Biotechnology, Laboratories of Biochemistry, University of Pavia, Pavia, Italy.
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16
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Soto-Pantoja DR, Kaur S, Roberts DD. CD47 signaling pathways controlling cellular differentiation and responses to stress. Crit Rev Biochem Mol Biol 2015; 50:212-30. [PMID: 25708195 DOI: 10.3109/10409238.2015.1014024] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CD47 is a widely expressed integral membrane protein that serves as the counter-receptor for the inhibitory phagocyte receptor signal-regulatory protein-α (SIRPα) and as a signaling receptor for the secreted matricellular protein thrombospondin-1. Recent studies employing mice and somatic cells lacking CD47 have revealed important pathophysiological functions of CD47 in cardiovascular homeostasis, immune regulation, resistance of cells and tissues to stress and chronic diseases of aging including cancer. With the emergence of experimental therapeutics targeting CD47, a more thorough understanding of CD47 signal transduction is essential. CD47 lacks a substantial cytoplasmic signaling domain, but several cytoplasmic binding partners have been identified, and lateral interactions of CD47 with other membrane receptors play important roles in mediating signaling resulting from the binding of thrombospondin-1. This review addresses recent advances in identifying the lateral binding partners, signal transduction pathways and downstream transcription networks regulated through CD47 in specific cell lineages. Major pathways regulated by CD47 signaling include calcium homeostasis, cyclic nucleotide signaling, nitric oxide and hydrogen sulfide biosynthesis and signaling and stem cell transcription factors. These pathways and other undefined proximal mediators of CD47 signaling regulate cell death and protective autophagy responses, mitochondrial biogenesis, cell adhesion and motility and stem cell self-renewal. Although thrombospondin-1 is the best characterized agonist of CD47, the potential roles of other members of the thrombospondin family, SIRPα and SIRPγ binding and homotypic CD47 interactions as agonists or antagonists of signaling through CD47 should also be considered.
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Affiliation(s)
- David R Soto-Pantoja
- a Laboratory of Pathology , Center for Cancer Research, National Cancer Institute, National Institutes of Health , Bethesda , MD , USA
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17
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Liao CY, Lee CL, Wang HC, Liang SS, Kung PH, Wu YC, Chang FR, Wu CC. CLL2-1, a chemical derivative of orchid 1,4-phenanthrenequinones, inhibits human platelet aggregation through thiol modification of calcium-diacylglycerol guanine nucleotide exchange factor-I (CalDAG-GEFI). Free Radic Biol Med 2015; 78:101-10. [PMID: 25451646 DOI: 10.1016/j.freeradbiomed.2014.10.512] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 10/14/2014] [Accepted: 10/14/2014] [Indexed: 11/29/2022]
Abstract
CalDAG-GEFI is a guanine nucleotide exchange factor, which actives small GTPase Rap1 and plays an important role in platelet aggregation. Our previous study has shown that CalDAG-GEFI contains redox-sensitive thiols, and its function can be inhibited by thiol modification. In the present study, the effect of CLL2-1, a 1,4-phenanthrenequinone, on CalDAG-GEFI and platelet functions was investigated. In human platelets, CLL2-1 prevented platelet aggregation caused by various stimulators. Flow cytometric analysis revealed that CLL2-1 inhibited GPIIb/IIIa activation and P-selectin secretion. Moreover, CLL2-1 prevented Rap1 activation caused by thrombin, the Ca(2+) ionophore A23187, and the diacylglycerol mimetic phorbol 12-myristate 13-acetate, while only slightly inhibited thrombin-induced increases in [Ca(2+)]i and did not inhibit protein kinase C activation. Western blots after reducing SDS-PAGE showed that treatment of either platelets or platelet lysates with CLL2-1 led to a decrease of monomeric CalDAG-GEFI and appearance of cross-linked oligomers of CalDAG-GEFI, and these effects were inhibited by pretreatment of platelets or lysates with thiol reducing agents prior to the addition of CLL2-1, indicating thiol modification of CalDAG-GEFI by CLL2-1. Furthermore, the thiol reducing agents also prevented the inhibitory effect of CLL2-1 on Rap1 activation, GPIIb/IIIa activation, and platelet aggregation. In CalDAG-GEFI-overexpressing human embryonic kidney 293T cells, CLL2-1 also inhibited CalDAG-GEFI-mediated Rap1 activation. Taken together, our results suggest that the antiplatelet effect of CLL2-1 is due to, at least in part, inhibition of CalDAG-GEFI-mediated Rap1 activation, and provide the basis for development of novel antiplatelet drugs.
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Affiliation(s)
- Chieh-Yu Liao
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chia-Lin Lee
- School of Pharmacy, College of Pharmacy, China Medical University, Taichung, Taiwan
| | - Hui-Chun Wang
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Shih-Shin Liang
- Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Po-Hsiung Kung
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yang-Chang Wu
- School of Pharmacy, College of Pharmacy, China Medical University, Taichung, Taiwan
| | - Fang-Rong Chang
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chin-Chung Wu
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Marine Biotechnology and Resources, National Sun Yat-Sen University, Kaohsiung, Taiwan.
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18
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Guidetti GF, Torti M. Pull-down assay for analysis of integrin-mediated activation of Rap proteins in adherent platelets. Methods Mol Biol 2014; 1120:167-76. [PMID: 24470025 DOI: 10.1007/978-1-62703-791-4_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Rap1 GTPases operate as molecular switches by cycling between a GDP-bound inactive state and a GTP-bound active state and regulate several cellular pathways in response to different stimuli. Circulating blood platelets express high levels of Rap1 proteins, mainly Rap1b, which plays a critical role in platelet adhesion and activation. Rap1 is a key element in the inside-out signaling pathway leading to the conversion of integrins into the high-affinity state for their ligands. In platelets, Rap1b regulates inside-out activation of both integrin αIIbβ3 and α2β1. In addition, Rap1b is also involved in integrin outside-in signaling. Integrin-mediated platelet adhesion leads to accumulation of GTP-bound Rap1b, which promotes integrin-mediated processes such as spreading and clot retraction. Rap1b is thus a bidirectional regulator of platelet integrin function. Here we describe a method to analyze Rap1b activation induced by platelet adhesion via integrin α2β1.
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19
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Canault M, Ghalloussi D, Grosdidier C, Guinier M, Perret C, Chelghoum N, Germain M, Raslova H, Peiretti F, Morange PE, Saut N, Pillois X, Nurden AT, Cambien F, Pierres A, van den Berg TK, Kuijpers TW, Alessi MC, Tregouet DA. Human CalDAG-GEFI gene (RASGRP2) mutation affects platelet function and causes severe bleeding. ACTA ACUST UNITED AC 2014; 211:1349-62. [PMID: 24958846 PMCID: PMC4076591 DOI: 10.1084/jem.20130477] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
First case of a human RASGRP2 mutation affecting Rap1 activation in platelets and causing severe bleeding. The nature of an inherited platelet disorder was investigated in three siblings affected by severe bleeding. Using whole-exome sequencing, we identified the culprit mutation (cG742T) in the RAS guanyl-releasing protein-2 (RASGRP2) gene coding for calcium- and DAG-regulated guanine exchange factor-1 (CalDAG-GEFI). Platelets from individuals carrying the mutation present a reduced ability to activate Rap1 and to perform proper αIIbβ3 integrin inside-out signaling. Expression of CalDAG-GEFI mutant in HEK293T cells abolished Rap1 activation upon stimulation. Nevertheless, the PKC- and ADP-dependent pathways allow residual platelet activation in the absence of functional CalDAG-GEFI. The mutation impairs the platelet’s ability to form thrombi under flow and spread normally as a consequence of reduced Rac1 GTP-binding. Functional deficiencies were confined to platelets and megakaryocytes with no leukocyte alteration. This contrasts with the phenotype seen in type III leukocyte adhesion deficiency caused by the absence of kindlin-3. Heterozygous did not suffer from bleeding and have normal platelet aggregation; however, their platelets mimicked homozygous ones by failing to undergo normal adhesion under flow and spreading. Rescue experiments on cultured patient megakaryocytes corrected the functional deficiency after transfection with wild-type RASGRP2. Remarkably, the presence of a single normal allele is sufficient to prevent bleeding, making CalDAG-GEFI a novel and potentially safe therapeutic target to prevent thrombosis.
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Affiliation(s)
- Matthias Canault
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR_S 1062, 13005 Marseille, France Inra, UMR_INRA 1260, 13005 Marseille, France Aix Marseille Université, 13005 Marseille, France
| | - Dorsaf Ghalloussi
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR_S 1062, 13005 Marseille, France Inra, UMR_INRA 1260, 13005 Marseille, France Aix Marseille Université, 13005 Marseille, France
| | - Charlotte Grosdidier
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR_S 1062, 13005 Marseille, France Inra, UMR_INRA 1260, 13005 Marseille, France Aix Marseille Université, 13005 Marseille, France
| | - Marie Guinier
- Post-Genomic Platform of Pitié-Salpêtrière (P3S), Pierre and Marie Curie University, F-75013 Paris, France
| | - Claire Perret
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1166, F-75013 Paris, France Inserm, UMR_S 1166, Team Genomics and Pathophysiology of Cardiovascular Diseases, F-75013 Paris, France ICAN Institute for Cardiometabolism and Nutrition, F-75013 Paris, France
| | - Nadjim Chelghoum
- Post-Genomic Platform of Pitié-Salpêtrière (P3S), Pierre and Marie Curie University, F-75013 Paris, France
| | - Marine Germain
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1166, F-75013 Paris, France Inserm, UMR_S 1166, Team Genomics and Pathophysiology of Cardiovascular Diseases, F-75013 Paris, France ICAN Institute for Cardiometabolism and Nutrition, F-75013 Paris, France
| | - Hana Raslova
- Hématopoïèse Normale et Pathologique, Inserm Médicale U1009, 94805 Villejuif, France
| | - Franck Peiretti
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR_S 1062, 13005 Marseille, France Inra, UMR_INRA 1260, 13005 Marseille, France Aix Marseille Université, 13005 Marseille, France
| | - Pierre E Morange
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR_S 1062, 13005 Marseille, France Inra, UMR_INRA 1260, 13005 Marseille, France Aix Marseille Université, 13005 Marseille, France
| | - Noemie Saut
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR_S 1062, 13005 Marseille, France Inra, UMR_INRA 1260, 13005 Marseille, France Aix Marseille Université, 13005 Marseille, France
| | - Xavier Pillois
- LIRYC, Plateforme Technologique et d'Innovation Biomédicale, Hôpital Xavier Arnozan, Pessac, France Inserm, UMR_1034, 33600 Pessac, France
| | | | - François Cambien
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1166, F-75013 Paris, France Inserm, UMR_S 1166, Team Genomics and Pathophysiology of Cardiovascular Diseases, F-75013 Paris, France ICAN Institute for Cardiometabolism and Nutrition, F-75013 Paris, France
| | - Anne Pierres
- Aix Marseille Université, 13005 Marseille, France Inserm, UMR_1067, 13288 Marseille, France CNRS UMR_7333, 13288 Marseille, France
| | - Timo K van den Berg
- Department of Blood Cell Research, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, Netherlands
| | - Taco W Kuijpers
- Department of Blood Cell Research, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, Netherlands
| | - Marie-Christine Alessi
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR_S 1062, 13005 Marseille, France Inra, UMR_INRA 1260, 13005 Marseille, France Aix Marseille Université, 13005 Marseille, France
| | - David-Alexandre Tregouet
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1166, F-75013 Paris, France Inserm, UMR_S 1166, Team Genomics and Pathophysiology of Cardiovascular Diseases, F-75013 Paris, France ICAN Institute for Cardiometabolism and Nutrition, F-75013 Paris, France
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20
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Peng H, Luo J, Hao H, Hu J, Xie SK, Ren D, Rao B. MicroRNA-100 regulates SW620 colorectal cancer cell proliferation and invasion by targeting RAP1B. Oncol Rep 2014; 31:2055-62. [PMID: 24626817 DOI: 10.3892/or.2014.3075] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 01/29/2014] [Indexed: 11/06/2022] Open
Abstract
MicroRNAs (miRNAs) have been demonstrated to play important roles in tumorigenesis of human cancer. Fewer studies have explored the roles of miR-100 on human colorectal cancer cell proliferation and invasion. In this study, we utilized real-time PCR to verify whether miR-100 was downregulated in human colorectal cancer tissues compared with matched adjacent normal tissues. Functional studies demonstrated that ectopic expression of miR-100 inhabits cell growth and invasion and induce apoptosis, whereas knockdown of miR-100 yielded the reverse phenotype. Mechanistic studies reveal that miR-100 repressed the activity of a reporter gene fused to the 3'-untranslated region (3'-UTR) of RAP1B, whereas miR-100 silencing upregulated the expression of the reporter gene. Furthermore, we also detected that RAP1B mRNA was inversely expressed with miR-100 in colorectal cancer tissues. These data indicate that the miR-100 plays a tumor suppressor role by regulating colorectal cancer cell growth and invasion phenotype, and could serve as a potential maker for colorectal cancer therapy.
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Affiliation(s)
- Hui Peng
- Department of Colorectal and Anal Surgery, The Sixth Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510655, P.R. China
| | - Jun Luo
- Department of Colorectal and Anal Surgery, The Sixth Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510655, P.R. China
| | - Hu Hao
- Department of Pediatrics, The Sixth Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510655, P.R. China
| | - Jun Hu
- Guangdong Gastrointestinal Institute, The Sixth Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510655, P.R. China
| | - Shang-Kui Xie
- Department of Colorectal and Anal Surgery, The Sixth Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510655, P.R. China
| | - Donglin Ren
- Department of Colorectal and Anal Surgery, The Sixth Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510655, P.R. China
| | - Benqiang Rao
- Department of Gastrointestinal Anal Surgery and Institute of Gastroenterology, The Third Affiliated Hospital of Nanchang University, Nanchang 330008, P.R. China
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21
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β1 integrin−mediated signals are required for platelet granule secretion and hemostasis in mouse. Blood 2013; 122:2723-31. [DOI: 10.1182/blood-2013-06-508721] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Key Points
Platelet β1 integrin−mediated signals control granule secretion and hemostasis β1 integrin−mediated outside-in signaling is independent of direct kindlin-integrin interaction
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22
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Phosphorylation of the guanine-nucleotide-exchange factor CalDAG-GEFI by protein kinase A regulates Ca(2+)-dependent activation of platelet Rap1b GTPase. Biochem J 2013; 453:115-23. [PMID: 23600630 DOI: 10.1042/bj20130131] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In blood platelets the small GTPase Rap1b is activated by cytosolic Ca2+ and promotes integrin αIIbβ3 inside-out activation and platelet aggregation. cAMP is the major inhibitor of platelet function and antagonizes Rap1b stimulation through a mechanism that remains unclear. In the present study we demonstrate that the Ca2+-dependent exchange factor for Rap1b, CalDAG-GEFI (calcium and diacylglycerol-regulated guanine-nucleotide-exchange factor I), is a novel substrate for the cAMP-activated PKA (protein kinase A). CalDAG-GEFI phosphorylation occurred in intact platelets treated with the cAMP-increasing agent forskolin and was inhibited by the PKA inhibitor H89. Purified recombinant CalDAG-GEFI was also phosphorylated in vitro by the PKA catalytic subunit. By screening a panel of specific serine to alanine residue mutants, we identified Ser116 and Ser586 as PKA phosphorylation sites in CalDAG-GEFI. In transfected HEK (human embryonic kidney)-293 cells, as well as in platelets, forskolin-induced phosphorylation of CalDAG-GEFI prevented the activation of Rap1b induced by the Ca2+ ionophore A23187. In platelets this effect was associated with the inhibition of aggregation. Moreover, cAMP-mediated inhibition of Rap1b was lost in HEK-293 cells transfected with a double mutant of CalDAG-GEFI unable to be phosphorylated by PKA. The results of the present study demonstrate that phosphorylation of CalDAG-GEFI by PKA affects its activity and represents a novel mechanism for cAMP-mediated inhibition of Rap1b in platelets.
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Subramanian H, Zahedi RP, Sickmann A, Walter U, Gambaryan S. Phosphorylation of CalDAG-GEFI by protein kinase A prevents Rap1b activation. J Thromb Haemost 2013; 11:1574-82. [PMID: 23611601 DOI: 10.1111/jth.12271] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 04/17/2013] [Indexed: 11/24/2022]
Abstract
BACKGROUND Signaling via protein kinase A (PKA) and protein kinase G (PKG) is critical for maintaining platelets in the resting state. Both kinases down-regulate the activity of the small GTPase Rap1b, a critical signaling switch for integrin activation and platelet aggregation. However, the mechanism of Rap1b regulation by PKA and PKG is largely unknown. OBJECTIVE To identify the PKA phosphorylation sites in calcium and diacylglycerol-regulated guanine nucleotide exchange factor I (CalDAG-GEFI), the main GEF for Rap1b in platelets, and the effect of CalDAG-GEFI phosphorylation in Rap1b activation. METHODS The phosphorylation sites in CalDAG-GEFI were identified by radio-active phosphate incorporation assay and mass spectrometry. Phospho-antibody was developed to detect CalDAG-GEFI phosphorylation in Western blots. Rap1b activation was detected by Rap1-GTP pull-down assay. RESULTS S587 was identified as the major PKA phosphorylation site in CalDAG-GEFI, while S116/117 was weakly phosphorylated. Phosphorylation of S587 correlated with the inhibitory effect of PKA on Rap1b activation in platelets. In HEK293 cells, expression of a phospho-mimetic mutant of CalDAG-GEFI (S587D) abolished agonist-induced Rap1b activation. Mutation of S587 to alanine partially reversed the inhibitory effect of PKA signaling on Rap1b activation, while mutation of S116, S117 and S587 to alanine completely abolished the inhibitory effect of PKA on Rap1b activation. CONCLUSION Our study strongly suggests that phosphorylation of CalDAG-GEFI is a critical mechanism by which PKA controls Rap1b-dependent platelet aggregation.
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Affiliation(s)
- H Subramanian
- Institute of Clinical Biochemistry and Pathobiochemistry, University of Wuerzburg, Wuerzburg, Germany
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Ferroni P, Vazzana N, Riondino S, Cuccurullo C, Guadagni F, Davì G. Platelet function in health and disease: from molecular mechanisms, redox considerations to novel therapeutic opportunities. Antioxid Redox Signal 2012; 17:1447-85. [PMID: 22458931 DOI: 10.1089/ars.2011.4324] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Increased oxidative stress appears to be of fundamental importance in the pathogenesis and development of several disease processes. Indeed, it is well known that reactive oxygen species (ROS) exert critical regulatory functions within the vascular wall, and it is, therefore, plausible that platelets represent a relevant target for their action. Platelet activation cascade (including receptor-mediated tethering to the endothelium, rolling, firm adhesion, aggregation, and thrombus formation) is tightly regulated. In addition to already well-defined platelet regulatory factors, ROS may participate in the regulation of platelet activation. It is already established that enhanced ROS release from the vascular wall can indirectly affect platelet activity by scavenging nitric oxide (NO), thereby decreasing the antiplatelet properties of endothelium. On the other hand, recent data suggest that platelets themselves generate ROS, which may evoke pro-thrombotic responses, triggering many biological processes participating in atherosclerosis initiation, progression, and complication. That oxidative stress may alter platelet function is conceivable when considering that antioxidants play a role in the prevention of cardiovascular disease, although the precise mechanism accounting for changes attributable to antioxidants in atherosclerosis remains unknown. It is possible that the effects of antioxidants may be a consequence of their enhancing or promoting the antiplatelet effects of NO derived from both endothelial cells and platelets. This review focuses on current knowledge regarding ROS-dependent regulation of platelet function in health and disease, and summarizes in vitro and in vivo evidence for their physiological and potential therapeutic relevance.
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Affiliation(s)
- Patrizia Ferroni
- Department of Laboratory Medicine and Advanced Biotechnologies, IRCCS San Raffaele Pisana, Rome, Italy
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Nanoparticles induce platelet activation in vitro through stimulation of canonical signalling pathways. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2012; 8:1329-36. [DOI: 10.1016/j.nano.2012.04.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 04/03/2012] [Accepted: 04/12/2012] [Indexed: 01/21/2023]
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Su X, Floyd DH, Hughes A, Xiang J, Schneider JG, Uluckan O, Heller E, Deng H, Zou W, Craft CS, Wu K, Hirbe AC, Grabowska D, Eagleton MC, Townsley S, Collins L, Piwnica-Worms D, Steinberg TH, Novack DV, Conley PB, Hurchla MA, Rogers M, Weilbaecher KN. The ADP receptor P2RY12 regulates osteoclast function and pathologic bone remodeling. J Clin Invest 2012; 122:3579-92. [PMID: 22996695 DOI: 10.1172/jci38576] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 07/26/2012] [Indexed: 12/16/2022] Open
Abstract
The adenosine diphosphate (ADP) receptor P2RY12 (purinergic receptor P2Y, G protein coupled, 12) plays a critical role in platelet aggregation, and P2RY12 inhibitors are used clinically to prevent cardiac and cerebral thrombotic events. Extracellular ADP has also been shown to increase osteoclast (OC) activity, but the role of P2RY12 in OC biology is unknown. Here, we examined the role of mouse P2RY12 in OC function. Mice lacking P2ry12 had decreased OC activity and were partially protected from age-associated bone loss. P2ry12-/- OCs exhibited intact differentiation markers, but diminished resorptive function. Extracellular ADP enhanced OC adhesion and resorptive activity of WT, but not P2ry12-/-, OCs. In platelets, ADP stimulation of P2RY12 resulted in GTPase Ras-related protein (RAP1) activation and subsequent αIIbβ3 integrin activation. Likewise, we found that ADP stimulation induced RAP1 activation in WT and integrin β3 gene knockout (Itgb3-/-) OCs, but its effects were substantially blunted in P2ry12-/- OCs. In vivo, P2ry12-/- mice were partially protected from pathologic bone loss associated with serum transfer arthritis, tumor growth in bone, and ovariectomy-induced osteoporosis: all conditions associated with increased extracellular ADP. Finally, mice treated with the clinical inhibitor of P2RY12, clopidogrel, were protected from pathologic osteolysis. These results demonstrate that P2RY12 is the primary ADP receptor in OCs and suggest that P2RY12 inhibition is a potential therapeutic target for pathologic bone loss.
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Affiliation(s)
- Xinming Su
- Department of Medicine, Division of Oncology, Washington University in St. Louis School of Medicine, St. Louis, Missouri 63110, USA
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27
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The Small GTPase Rap1b: A Bidirectional Regulator of Platelet Adhesion Receptors. JOURNAL OF SIGNAL TRANSDUCTION 2012; 2012:412089. [PMID: 22745904 PMCID: PMC3382407 DOI: 10.1155/2012/412089] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 04/12/2012] [Accepted: 04/27/2012] [Indexed: 11/27/2022]
Abstract
Integrins and other families of cell adhesion receptors are responsible for platelet adhesion and aggregation, which are essential steps for physiological haemostasis, as well as for the development of thrombosis. The modulation of platelet adhesive properties is the result of a complex pattern of inside-out and outside-in signaling pathways, in which the members of the Rap family of small GTPases are bidirectionally involved.
This paper focuses on the regulation of the main Rap GTPase expressed in circulating platelets, Rap1b, downstream of adhesion receptors, and summarizes the most recent achievements in the investigation of the function of this protein as regulator of platelet adhesion and thrombus formation.
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29
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Boudreaux MK. Inherited platelet disorders. J Vet Emerg Crit Care (San Antonio) 2012; 22:30-41. [PMID: 22316339 DOI: 10.1111/j.1476-4431.2011.00702.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 11/22/2011] [Indexed: 01/06/2023]
Abstract
OBJECTIVE To present the latest information on inherited platelet disorders in domestic animals. DATA SOURCES Research articles and reviews spanning 40 years available on PubMed. HUMAN DATA SYNTHESIS Information regarding inherited platelet disorders in people is plentiful and often descriptions of human conditions have led to the identification of similar disorders in veterinary species. There are exceptions, however, in which specific inherited platelet disorders were first described in animals with subsequent identification in people. VETERINARY DATA SYNTHESIS Many inherited platelet disorders have been documented in animals at the functional and molecular level and that information is presented in this review. CONCLUSIONS Much progress has been made in the past 20 years in the characterization of inherited platelet disorders in animals at the functional, biochemical, and molecular level. The study of inherited platelet disorders has greatly enhanced the understanding of platelet physiology and has led in some instances to the development of platelet inhibitory medications. Characterization of inherited disorders at the molecular level greatly facilitates diagnosis and identification of affected and heterozygous animals thus avoiding propagation of the defect by breeders. When used with available functional and biochemical diagnostic tests, it significantly enhances the quality of care and case management.
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Affiliation(s)
- Mary K Boudreaux
- From the Department of Pathobiology, College of Veterinary Medicine, Auburn University, AL 36849-5519, USA.
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Agle KA, Vongsa RA, Dwinell MB. Chemokine stimulation promotes enterocyte migration through laminin-specific integrins. Am J Physiol Gastrointest Liver Physiol 2011; 301:G968-80. [PMID: 21921288 PMCID: PMC3233784 DOI: 10.1152/ajpgi.00208.2011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Intestinal homeostasis is regulated in part by the single cell layer of the mucosal epithelium. This physical barrier is a prominent part of the innate immune system and possesses an intrinsic ability to heal damage and limit infection. The restitutive epithelial migration phase of healing requires dynamic integrin adhesion to the extracellular matrix. Previously, we have shown that the homeostatic chemokine CXCL12 utilizes intracellular calcium to increase enterocyte migration on laminin. The aim of these studies was to investigate integrin specificity and, in turn, functional responses elicited by CXCL12 stimulation. Analysis of cellular adhesion and spreading revealed CXCL12 preferentially activated laminin-specific integrins compared with collagen IV-binding integrins. Laminin-specific cell adhesion and spreading elicited by CXCL12 was dependent on intracellular calcium. CXCL12 increased activated β1-integrins on the surface of epithelial cells compared with untreated cells. RT-PCR confirmed expression of the laminin-binding integrins-α3β1, -α6β1, and -α6β4. Interestingly, shRNA-mediated depletion of laminin-specific α3- or α6-integrin subunits revealed differential functions. α3-Integrin knockdown reduced basal as well as inducible restitution. Depletion of α6-integrin specifically abolished CXCL12-stimulated, but not TGF-β1 or basal, migration. Depletion with either shα3-integrin or shα6-integrin prevented CXCL12-evoked cell spreading. Our data indicate that CXCL12 stimulates the inside-out activation of laminin-specific integrins to promote cell migratory functions. Together, our findings support the notion that extracellular mediators within the gastrointestinal mucosa coordinate cell-matrix interactions during epithelial restitution.
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Affiliation(s)
- Kimberle A. Agle
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Rebecca A. Vongsa
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Michael B. Dwinell
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin
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Abstract
Integrin α2β1-mediated adhesion of human platelets to monomeric type I collagen or to the GFOGER peptide caused a time-dependent activation of PI3K and Akt phosphorylation. This process was abrogated by pharmacologic inhibition of PI3Kβ, but not of PI3Kγ or PI3Kα. Moreover, Akt phosphorylation was undetectable in murine platelets expressing a kinase-dead mutant of PI3Kβ (PI3Kβ(KD)), but occurred normally in PI3Kγ(KD) platelets. Integrin α2β1 failed to stimulate PI3Kβ in platelets from phospholipase Cγ2 (PLCγ2)-knockout mice, and we found that intracellular Ca(2+) linked PLCγ2 to PI3Kβ activation. Integrin α2β1 also caused a time-dependent stimulation of the focal kinase Pyk2 downstream of PLCγ2 and intracellular Ca(2+). Whereas activation of Pyk2 occurred normally in PI3Kβ(KD) platelets, stimulation of PI3Kβ was strongly reduced in Pyk2-knockout mice. Neither Pyk2 nor PI3Kβ was required for α2β1-mediated adhesion and spreading. However, activation of Rap1b and inside-out stimulation of integrin αIIbβ3 were reduced after inhibition of PI3Kβ and were significantly impaired in Pyk2-deficient platelets. Finally, both PI3Kβ and Pyk2 significantly contributed to thrombus formation under flow. These results demonstrate that Pyk2 regulates PI3Kβ downstream of integrin α2β1, and document a novel role for Pyk2 and PI3Kβ in integrin α2β1 promoted inside-out activation of integrin αIIbβ3 and thrombus formation.
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Abstract
Atherosclerotic cardiovascular disease is a major cause of morbidity and mortality in the Western world. Despite tremendous strides in understandings its pathogenesis, it still remains a challenge because of gaps in our understanding of its initiation, progression and complications leading to the clinical syndromes of angina, acute coronary syndrome, cerebrovascular disease and peripheral vascular disease. Recent studies have provided impetus on the shift from models of atherosclerosis based on cellular interactions to models where the important role of extracellular matrix is recognized. Proteoglycans, especially those belonging to the small leucine-rich proteoglycan family of which decorin is a representative example, have come under close scrutiny for their role in atherogenesis. There is evidence from in vitro and in vivo animal models as well as humans to suggest an important role of decorin in attenuating progression of atherosclerosis. Decorin distribution in different blood vessels has been shown to inversely correlate with the tendency to develop atherosclerosis. Decorin seems to interact closely with different cellular components of the plaque milieu, thereby suggesting its role in influencing atherogenesis at different steps. Here we review the current understanding of the role of decorin in the pathogenesis of atherosclerosis.
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Affiliation(s)
- Sandeep Singla
- Division of Cardiovascular Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
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33
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Zhang G, Xiang B, Ye S, Chrzanowska-Wodnicka M, Morris AJ, Gartner TK, Whiteheart SW, White GC, Smyth SS, Li Z. Distinct roles for Rap1b protein in platelet secretion and integrin αIIbβ3 outside-in signaling. J Biol Chem 2011; 286:39466-77. [PMID: 21940635 DOI: 10.1074/jbc.m111.239608] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rap1b is activated by platelet agonists and plays a critical role in integrin α(IIb)β(3) inside-out signaling and platelet aggregation. Here we show that agonist-induced Rap1b activation plays an important role in stimulating secretion of platelet granules. We also show that α(IIb)β(3) outside-in signaling can activate Rap1b, and integrin outside-in signaling-mediated Rap1b activation is important in facilitating platelet spreading on fibrinogen and clot retraction. Rap1b-deficient platelets had diminished ATP secretion and P-selectin expression induced by thrombin or collagen. Importantly, addition of low doses of ADP and/or fibrinogen restored aggregation of Rap1b-deficient platelets. Furthermore, we found that Rap1b was activated by platelet spreading on immobilized fibrinogen, a process that was not affected by P2Y(12) or TXA(2) receptor deficiency, but was inhibited by the selective Src inhibitor PP2, the PKC inhibitor Ro-31-8220, or the calcium chelator demethyl-1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis. Clot retraction was abolished, and platelet spreading on fibrinogen was diminished in Rap1b-deficient platelets compared with wild-type controls. The defects in clot retraction and spreading on fibrinogen of Rap1b-deficient platelets were not rescued by addition of MnCl(2), which elicits α(IIb)β(3) outside-in signaling in the absence of inside-out signaling. Thus, our results reveal two different activation mechanisms of Rap1b as well as novel functions of Rap1b in platelet secretion and in integrin α(IIb)β(3) outside-in signaling.
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Affiliation(s)
- Guoying Zhang
- Division of Cardiovascular Medicine, The Gill Heart Institute, University of Kentucky, Lexington, Kentucky 40536, USA
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Lovett M, Eng G, Kluge JA, Cannizzaro C, Vunjak-Novakovic G, Kaplan DL. Tubular silk scaffolds for small diameter vascular grafts. Organogenesis 2011; 6:217-24. [PMID: 21220960 DOI: 10.4161/org.6.4.13407] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Vascular surgeries such as coronary artery bypass require small diameter vascular grafts with properties that are not available at this time. Approaches using synthetic biomaterials have been not completely successful in producing non-thrombogenic grafts with inner diameters less than 6 mm, and there is a need for new biomaterials and graft designs. We propose silk fibroin as a microvascular graft material and describe tubular silk scaffolds that demonstrate improved properties over existing vascular graft materials. Silk tubes produced using an aqueous gel spinning technique were first assessed in vitro in terms of thrombogenicity (thrombin and fibrinogen adsorption, platelet adhesion) and vascular cell responses (endothelial and smooth muscle cell attachment and proliferation) in comparison with polytetrafluoroethylene (PTFE), a synthetic material most frequently used for vascular grafts. Silk tubes were then implanted into the abdominal aortas of Sprague-Dawley rats. At time points of 2 weeks and 4 weeks post implantation, tissue outcomes were assessed through gross observation (acute thrombosis, patency) and histological staining (H&E, Factor VIII, smooth muscle actin). Over the 4-week time period, we observed graft patency and endothelial cell lining of the lumen surfaces. These results demonstrate the feasibility of using silk fibroin as a vascular graft material and some advantages of silk tubes over the currently used synthetic grafts.
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Affiliation(s)
- Michael Lovett
- Department of Biomedical Engineering, Tufts University, Medford, MA, USA
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35
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Broos K, Feys HB, De Meyer SF, Vanhoorelbeke K, Deckmyn H. Platelets at work in primary hemostasis. Blood Rev 2011; 25:155-67. [PMID: 21496978 DOI: 10.1016/j.blre.2011.03.002] [Citation(s) in RCA: 272] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
When platelet numbers are low or when their function is disabled, the risk of bleeding is high, which on the one hand indicates that in normal life vascular damage is a rather common event and that hence the role of platelets in maintaining a normal hemostasis is a continuously ongoing physiological process. Upon vascular injury, platelets instantly adhere to the exposed extracellular matrix resulting in platelet activation and aggregation to form a hemostatic plug. This self-amplifying mechanism nevertheless requires a tight control to prevent uncontrolled platelet aggregate formation that eventually would occlude the vessel. Therefore endothelial cells produce inhibitory compounds such as prostacyclin and nitric oxide that limit the growth of the platelet thrombus to the damaged area. With this review, we intend to give an integrated survey of the platelet response to vascular injury in normal hemostasis.
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Affiliation(s)
- Katleen Broos
- Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Campus Kortrijk, Belgium.
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36
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Abstract
Rapid activation of platelets at sites of vascular injury is a critical event in thrombosis and hemostasis. Here, we review recent findings, which (a) identified CalDAG-GEFI (RasGRP2) at the nexus of the rapid Ca(2+)-dependent platelet activation, (b) demonstrated a complex synergy between signaling provided by CalDAG-GEFI, protein kinase C and the Gi-coupled receptor for ADP, P2Y12, and (c) suggested CalDAG-GEFI as a novel target for anti-platelet therapy.
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Affiliation(s)
- Lucia Stefanini
- Department of Medicine and Cardeza Foundation, Thomas Jefferson University, Philadelphia, PA, USA
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37
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Novel function for blood platelets and podoplanin in developmental separation of blood and lymphatic circulation. Blood 2010; 115:3997-4005. [PMID: 20110424 DOI: 10.1182/blood-2009-04-216069] [Citation(s) in RCA: 231] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
During embryonic development, lymph sacs form from the cardinal vein, and sprout centrifugally to form mature lymphatic networks. Separation of the lymphatic from the blood circulation by a hitherto unknown mechanism is essential for the homeostatic function of the lymphatic system. O-glycans on the lymphatic endothelium have recently been suggested to be required for establishment and maintenance of distinct blood and lymphatic systems, primarily by mediating proper function of podoplanin. Here, we show that this separation process critically involves platelet activation by podoplanin. We found that platelet aggregates build up in wild-type embryos at the separation zone of podoplanin(+) lymph sacs and cardinal veins, but not in podoplanin(-/-) embryos. Thus, podoplanin(-/-) mice develop a "nonseparation" phenotype, characterized by a blood-filled lymphatic network after approximately embryonic day 13.5, which, however, partially resolves in postnatal mice. The same embryonic phenotype is also induced by treatment of pregnant mice with acetyl salicylic acid, podoplanin-blocking antibodies, or by inactivation of the kindlin-3 gene required for platelet aggregation. Therefore, interaction of endothelial podoplanin of the developing lymph sac with circulating platelets from the cardinal vein is critical for separating the lymphatic from the blood vascular system.
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38
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Lee BY, Jethwaney D, Schilling B, Clemens DL, Gibson BW, Horwitz MA. The Mycobacterium bovis bacille Calmette-Guerin phagosome proteome. Mol Cell Proteomics 2010; 9:32-53. [PMID: 19815536 PMCID: PMC2808266 DOI: 10.1074/mcp.m900396-mcp200] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Indexed: 11/06/2022] Open
Abstract
Mycobacterium tuberculosis and Mycobacterium bovis bacille Calmette-Guérin (BCG) alter the maturation of their phagosomes and reside within a compartment that resists acidification and fusion with lysosomes. To define the molecular composition of this compartment, we developed a novel method for obtaining highly purified phagosomes from BCG-infected human macrophages and analyzed the phagosomes by Western immunoblotting and mass spectrometry-based proteomics. Our purification procedure revealed that BCG grown on artificial medium becomes less dense after growth in macrophages. By Western immunoblotting, LAMP-2, Niemann-Pick protein C1, and syntaxin 3 were readily detectable on the BCG phagosome but at levels that were lower than on the latex bead phagosome; flotillin-1 and the vacuolar ATPase were barely detectable on the BCG phagosome but highly enriched on the latex bead phagosome. Immunofluorescence studies confirmed the scarcity of flotillin on BCG phagosomes and demonstrated an inverse correlation between bacterial metabolic activity and flotillin on M. tuberculosis phagosomes. By mass spectrometry, 447 human host proteins were identified on BCG phagosomes, and a partially overlapping set of 289 human proteins on latex bead phagosomes was identified. Interestingly, the majority of the proteins identified consistently on BCG phagosome preparations were also identified on latex bead phagosomes, indicating a high degree of overlap in protein composition of these two compartments. It is likely that many differences in protein composition are quantitative rather than qualitative in nature. Despite the remarkable overlap in protein composition, we consistently identified a number of proteins on the BCG phagosomes that were not identified in any of our latex bead phagosome preparations, including proteins involved in membrane trafficking and signal transduction, such as Ras GTPase-activating-like protein IQGAP1, and proteins of unknown function, such as FAM3C. Our phagosome purification procedure and initial proteomics analyses set the stage for a quantitative comparative analysis of mycobacterial and latex bead phagosome proteomes.
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Affiliation(s)
- Bai-Yu Lee
- From the ‡Division of Infectious Diseases, Department of Medicine, Center for Health Sciences, University of California-Los Angeles School of Medicine, Los Angeles, California 90095-1688
| | - Deepa Jethwaney
- §Buck Institute for Age Research, Novato, California 94945, and
| | | | - Daniel L. Clemens
- From the ‡Division of Infectious Diseases, Department of Medicine, Center for Health Sciences, University of California-Los Angeles School of Medicine, Los Angeles, California 90095-1688
| | - Bradford W. Gibson
- §Buck Institute for Age Research, Novato, California 94945, and
- **Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94143
| | - Marcus A. Horwitz
- From the ‡Division of Infectious Diseases, Department of Medicine, Center for Health Sciences, University of California-Los Angeles School of Medicine, Los Angeles, California 90095-1688
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Genetic evidence for a predominant role of PI3Kβ catalytic activity in ITAM- and integrin-mediated signaling in platelets. Blood 2009; 114:2193-6. [DOI: 10.1182/blood-2009-03-208074] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Abstract
Phosphatidylinositol 3-kinase (PI3K) isoforms PI3Kβ and PI3Kγ are implicated in platelet adhesion, activation, and aggregation, but their relative contribution is still unclear or controversial. Here, we report the first comparative functional analysis of platelets from mice expressing a catalytically inactive form of PI3Kβ or PI3Kγ. We demonstrate that both isoforms were similarly required for maximal activation of the small GTPase Rap1b and for complete platelet aggregation upon stimulation of G protein–coupled receptors for adenosine 5′-diphosphate (ADP) or U46619. Their contribution to these events, however, was largely redundant and dispensable. However, PI3Kβ, but not PI3Kγ, enzymatic activity was absolutely required for Akt phosphorylation, Rap1 activation, and platelet aggregation downstream of the immunoreceptor tyrosine-based activation motif (ITAM)–bearing receptor glycoprotein VI (GPVI). Moreover, PI3Kβ was a major essential regulator of platelet adhesion to fibrinogen and of integrin αIIbβ3-mediated spreading. These results provide genetic evidence for a crucial and selective role of PI3Kβ in signaling through GPVI and integrin αIIbβ3.
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40
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Isa P, Sánchez-Alemán MA, López S, Arias CF. Dissecting the role of integrin subunits alpha 2 and beta 3 in rotavirus cell entry by RNA silencing. Virus Res 2009; 145:251-9. [PMID: 19635510 DOI: 10.1016/j.virusres.2009.07.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 07/15/2009] [Accepted: 07/17/2009] [Indexed: 12/16/2022]
Abstract
Several cell surface molecules have been implicated in rotavirus cell entry, however, their individual relevance during this process is unknown. In this work, the expression of integrins alpha2, beta2, and alpha v beta 3, the heat shock cognate protein 70, and of ganglioside GM1 in different cell lines of human and simian origin was correlated with the infectivity of four rotavirus strains. We observed that different combinations of receptor expression correlated with the infectivity of rotavirus strains, suggesting that the participation of several receptors is important for rotavirus infection. To characterize the relevance of integrins alpha2 and alpha v beta 3 in more detail, their expression was silenced using RNA interference. About 80% decrease in the cell content of integrins resulted in 15-30% decrease of infectivity of strains RRV and Wa when measured by a focus-forming assay, while there was no decrease of infectivity when measured by flow cytometry in integrin-deficient cells. Altogether these data suggest that integrins alpha2 and alpha v beta 3 do not play a major role in the rotavirus entry process.
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Affiliation(s)
- Pavel Isa
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, CP 62210 Cuernavaca, Morelos, Mexico.
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41
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Abstract
The importance of the second messengers calcium (Ca(2+)) and diacylglycerol (DAG) in platelet signal transduction was established more than 30 years ago. Whereas protein kinase C (PKC) family members were discovered as the targets of DAG, little is known about the molecular identity of the main Ca(2+) sensor(s). We here identify Ca(2+) and DAG-regulated guanine nucleotide exchange factor I (CalDAG-GEFI) as a critical molecule in Ca(2+)-dependent platelet activation. CalDAG-GEFI, through activation of the small GTPase Rap1, directly triggers integrin activation and extracellular signal-regulated kinase-dependent thromboxane A(2) (TxA(2)) release. CalDAG-GEFI-dependent TxA(2) generation provides crucial feedback for PKC activation and granule release, particularly at threshold agonist concentrations. PKC/P2Y12 signaling in turn mediates a second wave of Rap1 activation, necessary for sustained platelet activation and thrombus stabilization. Our results lead to a revised model for platelet activation that establishes one molecule, CalDAG-GEFI, at the nexus of Ca(2+)-induced integrin activation, TxA(2) generation, and granule release. The preferential activation of CalDAG-GEFI over PKC downstream of phospholipase C activation, and the different kinetics of CalDAG-GEFI- and PKC/P2Y12-mediated Rap1 activation demonstrate an unexpected complexity to the platelet activation process, and they challenge the current model that DAG/PKC-dependent signaling events are crucial for the initiation of platelet adhesion.
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Guidetti GF, Bernardi B, Consonni A, Rizzo P, Gruppi C, Balduini C, Torti M. Integrin alpha2beta1 induces phosphorylation-dependent and phosphorylation-independent activation of phospholipase Cgamma2 in platelets: role of Src kinase and Rac GTPase. J Thromb Haemost 2009; 7:1200-6. [PMID: 19422462 DOI: 10.1111/j.1538-7836.2009.03444.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BACKGROUND Platelet adhesion promoted by integrin alpha2beta1 induces integrin alpha(IIb)beta3 activation through the phospholipase C (PLC)-dependent stimulation of the small GTPase Rap1b. OBJECTIVE To analyze the mechanism of PLC activation downstream of alpha2beta1 that is required for regulation of Rap1b and alpha(IIb)beta3. METHODS Human and murine platelets were allowed to adhere to immobilized type I monomeric collagen through alpha2beta1. Tyrosine phosphorylation of PLCgamma2, PLC activation, accumulation of GTP-bound Rap1b and fibrinogen binding were measured and compared. RESULTS Integrin alpha2beta1 recruitment induced an evident PLC activation that was concomitant with robust tyrosine phosphorylation of PLCgamma2, and was suppressed in platelets from PLCgamma2-knockout mice. Moreover, PLCgamma2(-/-) platelets were unable to accumulate active Rap1b and to activate alpha(IIb)beta3 upon adhesion through alpha2beta1. Inhibition of Src kinases completely prevented tyrosine phosphorylation of PLCgamma2 in adherent platelets, but did not affect its activation, and both Rap1b and alpha(IIb)beta3 stimulation occurred normally. Importantly, alpha(IIb)beta3-induced phosphorylation and activation of PLCgamma2, as well as accumulation of active Rap1b, were totally suppressed by Src inhibition. Integrin alpha2beta1 recruitment triggered the Src kinase-independent activation of the small GTPase Rac1, and activation of Rac1 was not required for PLCgamma2 phosphorylation. However, when phosphorylation of PLCgamma2 was blocked by the Src kinase inhibitor PP2, prevention of Rac1 activation significantly reduced PLCgamma2 activation, GTP-Rap1b accumulation, and alpha(IIb)beta3 stimulation. CONCLUSIONS Src kinases and the Rac GTPases mediate independent pathways for PLCgamma2 activation downstream of alpha2beta1.
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Affiliation(s)
- G F Guidetti
- Department of Biochemistry, University of Pavia, Pavia, Italy
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Li X, Stankovic M, Lee BPL, Aurrand-Lions M, Hahn CN, Lu Y, Imhof BA, Vadas MA, Gamble JR. JAM-C induces endothelial cell permeability through its association and regulation of {beta}3 integrins. Arterioscler Thromb Vasc Biol 2009; 29:1200-6. [PMID: 19461049 DOI: 10.1161/atvbaha.109.189217] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE The molecular mechanisms regulating vascular permeability are only now being elucidated. The junctional adhesion molecule (JAM) JAM-C has been linked to the induction of vascular permeability. We sought to understand the mechanism whereby JAM-C may disrupt junctional integrity in endothelial cells (ECs). METHODS AND RESULTS We show here that JAM-C alters permeability through modulation of integrin activity. JAM-C overexpression results in an increase in JAM-C at junctions and an increase in permeability. Conversely, knockdown of JAM-C by siRNA results in a reduction in permeability. JAM-C associates with alphavbeta3 integrin and regulates its localization and activity. JAM-C also inhibits the activation state of the beta(1) integrin although it does not associate with this integrin. These changes induced on the integrins are mediated through regulation of the small GTPase, Rap1b but not Rap1a. Thrombin, a powerful inductor of vascular leak, causes localization of JAM-C into the junctions, whereas angiopoietin-1, an inhibitor of permeability, prevents JAM-C translocation. CONCLUSIONS The regulation of EC junctional integrity involves the coordinated and dynamic modification of localization and activity of junctional stabilizers such as the integrin beta(3) and the destabilizer, JAM-C.
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Affiliation(s)
- Xiaochun Li
- Centenary Institute of Cancer Medicine and Cell Biology, Locked bag#6, Newtown, NSW, Australia
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44
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Mechanisms regulating increased production of osteoprotegerin by osteoblasts cultured on microstructured titanium surfaces. Biomaterials 2009; 30:3390-6. [PMID: 19395022 DOI: 10.1016/j.biomaterials.2009.03.047] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Accepted: 03/11/2009] [Indexed: 01/05/2023]
Abstract
Osteoblasts grown on microstructured Ti surfaces enhance osteointegration by producing local factors that regulate bone formation as well as bone remodeling, including the RANK ligand decoy receptor osteoprotegerin (OPG). The objective of this study was to explore the mechanism by which surface microstructure and surface energy mediate their stimulatory effects on OPG expression. Titanium disks were manufactured to present different surface morphologies: a smooth pretreatment surface (PT, Ra<0.2microm), microstructured sandblasted/acid etched surface (SLA, Ra=3-4microm), and a microstructured Ti plasma-sprayed surface (TPS, Ra=4microm). Human osteoblast-like MG63 cells were cultured on these substrates and the regulation of OPG production by TGF-beta1, PKC, and alpha2beta1 integrin signaling determined. Osteoblasts produced increased amounts of OPG as well as active and latent TGF-beta1 and had increased PKC activity when grown on SLA and TPS. Exogenous TGF-beta1 increased OPG production in a dose-dependent manner on all surfaces, and this was prevented by adding blocking antibody to the TGF-beta type II receptor or by reducing TGF-beta1 binding to the receptor by adding exogenous soluble type II receptor. The PKC inhibitor chelerythrine inhibited the production of OPG in a dose-dependent manner, but only in cultures on SLA and TPS. shRNA knockdown of alpha2 or a double knockdown of alpha2beta1 also reduced OPG, as well as production of TGF-beta1. These results indicate that substrate-dependent OPG production is regulated by TGF-beta1, PKC, and alpha2beta1 and suggest a mechanism by which alpha2beta1 signaling increases PKC, resulting in TGF-beta1 production and TGF-beta1 then acts on its receptor to increase transcription of OPG.
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Gresele P, Falcinelli E, Giannini S, D'Adamo P, D'Eustacchio A, Corazzi T, Mezzasoma AM, Di Bari F, Guglielmini G, Cecchetti L, Noris P, Balduini CL, Savoia A. Dominant inheritance of a novel integrin beta3 mutation associated with a hereditary macrothrombocytopenia and platelet dysfunction in two Italian families. Haematologica 2009; 94:663-9. [PMID: 19336737 DOI: 10.3324/haematol.2008.002246] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Defects of integrin alpha(IIb)beta(3) are typical of Glanzmann's thrombasthenia, an inherited autosomal recessive bleeding disorder characterized by the failure of platelets to aggregate in response to all physiological agonists, but with no abnormalities in the number or size of platelets. Although large heterogeneity has been described for Glanzmann's thrombasthenia, no family has so far been described as having an autosomal dominant form of this disease. DESIGN AND METHODS We describe two Italian families with moderate thrombocytopenia with large platelets, defective platelet function and moderate/severe mucocutaneous bleeding, transmitted as an autosomal dominant trait and associated with a novel integrin beta(3)-gene (ITGB3) mutation. RESULTS The characteristics of our families are moderate macrothrombocytopenia and defective platelet function associated with a mild reduction of surface alpha(Ib) beta(3), impaired platelet aggregation to physiological agonists but not to ristocetin, normal clot retraction, reduced fibrinogen binding and expression of activated alpha(IIb)beta(3) upon stimulation, normal platelet adhesion to immobilized fibrinogen but reduced platelet spreading and tyrosine phosphorylation, indicating defective alpha(IIb)beta(3)-mediated outside-in signaling. Molecular analysis revealed a novel mutation of ITGB3 that determines an in-frame deletion producing the loss of amino acids 647-686 of the betaTD ectodomain of integrin beta(3). Haplotype analysis indicated that the two families inherited the mutation from a common ancestral chromosome. CONCLUSIONS This novel autosomal dominant macrothrombocytopenia associated with platelet dysfunction raises interesting questions about the role of integrin beta(3), and its betaTD domain, in platelet formation and function.
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Affiliation(s)
- Paolo Gresele
- Division of Internal and Cardiovascular Medicine, Department of Internal Medicine, University of Perugia, Via E. dal Pozzo, Perugia, Italy.
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46
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Bastian P, Balcarek A, Altanis C, Strell C, Niggemann B, Zaenker KS, Entschladen F. The inhibitory effect of norepinephrine on the migration of ES-2 ovarian carcinoma cells involves a Rap1-dependent pathway. Cancer Lett 2008; 274:218-24. [PMID: 18849110 DOI: 10.1016/j.canlet.2008.09.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Revised: 08/13/2008] [Accepted: 09/10/2008] [Indexed: 02/06/2023]
Abstract
Our previous studies have shown that norepinephrine induces the migratory activity of human PC-3 prostate, SW 480 colon and MDA-MB-468 breast carcinoma cells. In contrast to these results, we show here that human ES-2 ovarian carcinoma cells have a reduced migratory activity after norepinephrine treatment. This inhibitory effect is possibly mediated by a cAMP-dependent activation of the small GTPase Rap1 via Epac. Furthermore, a key signalling event of the promigratory effect of norepinephrine in the above mentioned carcinoma cells is the activation of phospholipase C enzymes. In ES-2 cells, this part of the signalling cascade is constitutively active.
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Affiliation(s)
- Philipp Bastian
- Institute of Immunology, Witten/Herdecke University, Stockumer Str. 10, 58448 Witten, Germany
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47
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Canobbio I, Trionfini P, Guidetti GF, Balduini C, Torti M. Targeting of the small GTPase Rap2b, but not Rap1b, to lipid rafts is promoted by palmitoylation at Cys176 and Cys177 and is required for efficient protein activation in human platelets. Cell Signal 2008; 20:1662-70. [DOI: 10.1016/j.cellsig.2008.05.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Accepted: 05/26/2008] [Indexed: 10/22/2022]
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48
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Guidetti GF, Lova P, Bernardi B, Campus F, Baldanzi G, Graziani A, Balduini C, Torti M. The Gi-coupled P2Y12 receptor regulates diacylglycerol-mediated signaling in human platelets. J Biol Chem 2008; 283:28795-805. [PMID: 18755689 DOI: 10.1074/jbc.m801588200] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Stimulation of G(q)-coupled receptors activates phospholipase C and is supposed to promote both intracellular Ca(2+) mobilization and protein kinase C (PKC) activation. We found that ADP-induced phosphorylation of pleckstrin, the main platelet substrate for PKC, was completely inhibited not only by an antagonist of the G(q)-coupled P2Y1 receptor but also upon blockade of the G(i)-coupled P2Y12 receptor. The role of G(i) on PKC regulation required stimulation of phosphatidylinositol 3-kinase rather than inhibition of adenylyl cyclase. P2Y12 antagonists also inhibited pleckstrin phosphorylation, Rap1b activation, and platelet aggregation induced upon G(q) stimulation by the thromboxane A(2) analogue U46619. Importantly, activation of phospholipase C and intracellular Ca(2+) mobilization occurred normally. Phorbol 12-myristate 13-acetate overcame the inhibitory effect of P2Y12 receptor blockade on PKC activation but not on Rap1b activation and platelet aggregation. By contrast, inhibition of diacylglycerol kinase restored both PKC and Rap1b activity and caused platelet aggregation. Stimulation of P2Y12 receptor or direct inhibition of diacylglycerol kinase potentiated the effect of membrane-permeable sn-1,2-dioctanoylglycerol on platelet aggregation and pleckstrin phosphorylation, in association with inhibition of its phosphorylation to phosphatidic acid. These results reveal a novel and unexpected role of the G(i)-coupled P2Y12 receptor in the regulation of diacylglycerol-mediated events in activated platelets.
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Affiliation(s)
- Gianni F Guidetti
- Center of Excellence for Applied Biology, Department of Biochemistry, University of Pavia, via Bassi 21, 27100 Pavia, Italy
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49
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Pula G, Poole AW. Critical roles for the actin cytoskeleton and cdc42 in regulating platelet integrin alpha2beta1. Platelets 2008; 19:199-210. [PMID: 18432521 DOI: 10.1080/09537100701777303] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The modified two-site model for platelet activation by collagen requires tight binding of platelets to collagen through integrin alpha2beta1, after its prior activation by inside-out signals initiated by GP VI. The inside-out signalling to alpha2beta1 is not well characterized although it is currently accepted that GPVI initiates signals that lead to regulation of this integrin. The aim of the study was to determine the role played by actin polymerization and the Rho family GTPase cdc42 in the regulation of alpha2beta1 integrin. We first show that GPVI- and non-GPVI-dependent signals differentially regulate distribution of alpha2beta1 receptors, where binding of platelets to collagen leads to redistribution of the integrin to areas of contact between platelet and collagen fibre. Binding of platelets to collagen also leads to activation of alpha2beta1 integrin, which is dependent upon actin polymerization and cdc42 activity, since activation is blocked by cytochalasin D and secramine A respectively. Adhesion of platelets to collagen is markedly diminished in the presence of these inhibitors, whereas adhesion to CRP- or fibrinogen-coated surfaces is not affected. Platelet aggregation to collagen, but not CRP or thrombin, is also markedly dependent upon actin polymerization and cdc42 activity. In conclusion these data suggest that actin polymerization and cdc42 are required for activation of integrin alpha2beta1, but not alpha(IIb)beta3, thereby critically regulating platelet adhesion to and activation by collagen. We therefore suggest a further modification to the current two-site two-step model for activation of platelets by collagen, where actin polymerization and cdc42 mediate a critical step in modulating alpha2beta1 activation, possibly through a positive feedback pathway from alpha2beta1 itself.
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Affiliation(s)
- Giordano Pula
- Department of Pharmacology, School of Medical Sciences, University Walk, Bristol, UK
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50
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Surin WR, Barthwal MK, Dikshit M. Platelet collagen receptors, signaling and antagonism: Emerging approaches for the prevention of intravascular thrombosis. Thromb Res 2008; 122:786-803. [DOI: 10.1016/j.thromres.2007.10.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2007] [Revised: 10/17/2007] [Accepted: 10/21/2007] [Indexed: 02/02/2023]
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