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ITIM receptors: more than just inhibitors of platelet activation. Blood 2017; 129:3407-3418. [PMID: 28465343 DOI: 10.1182/blood-2016-12-720185] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 04/24/2017] [Indexed: 12/12/2022] Open
Abstract
Since their discovery, immunoreceptor tyrosine-based inhibition motif (ITIM)-containing receptors have been shown to inhibit signaling from immunoreceptor tyrosine-based activation motif (ITAM)-containing receptors in almost all hematopoietic cells, including platelets. However, a growing body of evidence has emerged demonstrating that this is an oversimplification, and that ITIM-containing receptors are versatile regulators of platelet signal transduction, with functions beyond inhibiting ITAM-mediated platelet activation. PECAM-1 was the first ITIM-containing receptor identified in platelets and appeared to conform to the established model of ITIM-mediated attenuation of ITAM-driven activation. PECAM-1 was therefore widely accepted as a major negative regulator of platelet activation and thrombosis for many years, but more recent findings suggest a more complex role for this receptor, including the facilitation of αIIbβ3-mediated platelet functions. Since the identification of PECAM-1, several other ITIM-containing platelet receptors have been discovered. These include G6b-B, a critical regulator of platelet reactivity and production, and the noncanonical ITIM-containing receptor TREM-like transcript-1, which is localized to α-granules in resting platelets, binds fibrinogen, and acts as a positive regulator of platelet activation. Despite structural similarities and shared binding partners, including the Src homology 2 domain-containing protein-tyrosine phosphatases Shp1 and Shp2, knockout and transgenic mouse models have revealed distinct phenotypes and nonredundant functions for each ITIM-containing receptor in the context of platelet homeostasis. These roles are likely influenced by receptor density, compartmentalization, and as-yet unknown binding partners. In this review, we discuss the diverse repertoire of ITIM-containing receptors in platelets, highlighting intriguing new functions, controversies, and future areas of investigation.
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Smith CW, Thomas SG, Raslan Z, Patel P, Byrne M, Lordkipanidzé M, Bem D, Meyaard L, Senis YA, Watson SP, Mazharian A. Mice Lacking the Inhibitory Collagen Receptor LAIR-1 Exhibit a Mild Thrombocytosis and Hyperactive Platelets. Arterioscler Thromb Vasc Biol 2017; 37:823-835. [PMID: 28336561 DOI: 10.1161/atvbaha.117.309253] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 03/08/2017] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1) is a collagen receptor that belongs to the inhibitory immunoreceptor tyrosine-based inhibition motif-containing receptor family. It is an inhibitor of signaling via the immunoreceptor tyrosine-based activation motif-containing collagen receptor complex, glycoprotein VI-FcRγ-chain. It is expressed on hematopoietic cells, including immature megakaryocytes, but is not detectable on platelets. Although the inhibitory function of LAIR-1 has been described in leukocytes, its physiological role in megakaryocytes and in particular in platelet formation has not been explored. In this study, we investigate the role of LAIR-1 in megakaryocyte development and platelet production by generating LAIR-1-deficient mice. APPROACH AND RESULTS Mice lacking LAIR-1 exhibit a significant increase in platelet counts, a prolonged platelet half-life in vivo, and increased proplatelet formation in vitro. Interestingly, platelets from LAIR-1-deficient mice exhibit an enhanced reactivity to collagen and the glycoprotein VI-specific agonist collagen-related peptide despite not expressing LAIR-1, and mice showed enhanced thrombus formation in the carotid artery after ferric chloride injury. Targeted deletion of LAIR-1 in mice results in an increase in signaling downstream of the glycoprotein VI-FcRγ-chain and integrin αIIbβ3 in megakaryocytes because of enhanced Src family kinase activity. CONCLUSIONS Findings from this study demonstrate that ablation of LAIR-1 in megakaryocytes leads to increased Src family kinase activity and downstream signaling in response to collagen that is transmitted to platelets, rendering them hyper-reactive specifically to agonists that signal through Syk tyrosine kinases, but not to G-protein-coupled receptors.
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Affiliation(s)
- Christopher W Smith
- From the Institute of Cardiovascular Sciences, College of Medical and Dental Sciences (C.W.S., S.G.T., Z.R., P.P., M.B., M.L., Y.A.S., S.P.W., A.M.), and Institute of Applied Health Research, College of Medical and Dental Sciences (D.B.), University of Birmingham, United Kingdom; and Laboratory of Translational Immunology, Department of Immunology, University Medical Center Utrecht, the Netherlands (L.M.)
| | - Steven G Thomas
- From the Institute of Cardiovascular Sciences, College of Medical and Dental Sciences (C.W.S., S.G.T., Z.R., P.P., M.B., M.L., Y.A.S., S.P.W., A.M.), and Institute of Applied Health Research, College of Medical and Dental Sciences (D.B.), University of Birmingham, United Kingdom; and Laboratory of Translational Immunology, Department of Immunology, University Medical Center Utrecht, the Netherlands (L.M.)
| | - Zaher Raslan
- From the Institute of Cardiovascular Sciences, College of Medical and Dental Sciences (C.W.S., S.G.T., Z.R., P.P., M.B., M.L., Y.A.S., S.P.W., A.M.), and Institute of Applied Health Research, College of Medical and Dental Sciences (D.B.), University of Birmingham, United Kingdom; and Laboratory of Translational Immunology, Department of Immunology, University Medical Center Utrecht, the Netherlands (L.M.)
| | - Pushpa Patel
- From the Institute of Cardiovascular Sciences, College of Medical and Dental Sciences (C.W.S., S.G.T., Z.R., P.P., M.B., M.L., Y.A.S., S.P.W., A.M.), and Institute of Applied Health Research, College of Medical and Dental Sciences (D.B.), University of Birmingham, United Kingdom; and Laboratory of Translational Immunology, Department of Immunology, University Medical Center Utrecht, the Netherlands (L.M.)
| | - Maxwell Byrne
- From the Institute of Cardiovascular Sciences, College of Medical and Dental Sciences (C.W.S., S.G.T., Z.R., P.P., M.B., M.L., Y.A.S., S.P.W., A.M.), and Institute of Applied Health Research, College of Medical and Dental Sciences (D.B.), University of Birmingham, United Kingdom; and Laboratory of Translational Immunology, Department of Immunology, University Medical Center Utrecht, the Netherlands (L.M.)
| | - Marie Lordkipanidzé
- From the Institute of Cardiovascular Sciences, College of Medical and Dental Sciences (C.W.S., S.G.T., Z.R., P.P., M.B., M.L., Y.A.S., S.P.W., A.M.), and Institute of Applied Health Research, College of Medical and Dental Sciences (D.B.), University of Birmingham, United Kingdom; and Laboratory of Translational Immunology, Department of Immunology, University Medical Center Utrecht, the Netherlands (L.M.)
| | - Danai Bem
- From the Institute of Cardiovascular Sciences, College of Medical and Dental Sciences (C.W.S., S.G.T., Z.R., P.P., M.B., M.L., Y.A.S., S.P.W., A.M.), and Institute of Applied Health Research, College of Medical and Dental Sciences (D.B.), University of Birmingham, United Kingdom; and Laboratory of Translational Immunology, Department of Immunology, University Medical Center Utrecht, the Netherlands (L.M.)
| | - Linde Meyaard
- From the Institute of Cardiovascular Sciences, College of Medical and Dental Sciences (C.W.S., S.G.T., Z.R., P.P., M.B., M.L., Y.A.S., S.P.W., A.M.), and Institute of Applied Health Research, College of Medical and Dental Sciences (D.B.), University of Birmingham, United Kingdom; and Laboratory of Translational Immunology, Department of Immunology, University Medical Center Utrecht, the Netherlands (L.M.)
| | - Yotis A Senis
- From the Institute of Cardiovascular Sciences, College of Medical and Dental Sciences (C.W.S., S.G.T., Z.R., P.P., M.B., M.L., Y.A.S., S.P.W., A.M.), and Institute of Applied Health Research, College of Medical and Dental Sciences (D.B.), University of Birmingham, United Kingdom; and Laboratory of Translational Immunology, Department of Immunology, University Medical Center Utrecht, the Netherlands (L.M.)
| | - Steve P Watson
- From the Institute of Cardiovascular Sciences, College of Medical and Dental Sciences (C.W.S., S.G.T., Z.R., P.P., M.B., M.L., Y.A.S., S.P.W., A.M.), and Institute of Applied Health Research, College of Medical and Dental Sciences (D.B.), University of Birmingham, United Kingdom; and Laboratory of Translational Immunology, Department of Immunology, University Medical Center Utrecht, the Netherlands (L.M.)
| | - Alexandra Mazharian
- From the Institute of Cardiovascular Sciences, College of Medical and Dental Sciences (C.W.S., S.G.T., Z.R., P.P., M.B., M.L., Y.A.S., S.P.W., A.M.), and Institute of Applied Health Research, College of Medical and Dental Sciences (D.B.), University of Birmingham, United Kingdom; and Laboratory of Translational Immunology, Department of Immunology, University Medical Center Utrecht, the Netherlands (L.M.).
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Melhem M, Abu-Farha M, Antony D, Madhoun AA, Bacchelli C, Alkayal F, AlKhairi I, John S, Alomari M, Beales PL, Alsmadi O. Novel G6B gene variant causes familial autosomal recessive thrombocytopenia and anemia. Eur J Haematol 2017; 98:218-227. [PMID: 27743390 DOI: 10.1111/ejh.12819] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/07/2016] [Indexed: 12/25/2022]
Abstract
OBJECTIVE To characterize the underlying genetic and molecular defects in a consanguineous family with lifelong blood disorder manifested with thrombocytopenia (low platelets count) and anemia. METHODS Genetic linkage analysis, exome sequencing, and functional genomics were carried out to identify and characterize the defective gene. RESULTS We identified a novel truncation mutation (p.C108*) in chromosome 6 open reading frame 25 (C6orf25) gene in this family. We also showed the p.C108* mutation was responsible for destabilizing the encoded truncated G6B protein. Unlike the truncated form, wild-type G6B expression resulted in enhanced K562 differentiation into megakaryocytes and erythrocytes. C6orf25, also known as G6B, is an effector protein for the key hematopoiesis regulators, Src homology region 2 domain-containing phosphatases SHP-1 and SHP-2. CONCLUSION G6B seems to act through an autosomal recessive mode of disease transmission in this family and regarded as the gene responsible for the observed hematological disorder. This inference is well supported further by in vivo evidence where similar outcomes were reported from G6b-/- and SHP1/2 DKO mouse models.
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Affiliation(s)
- Motasem Melhem
- Genetics and Genomics Department, Dasman Diabetes Institute, Dasman, Kuwait
| | - Mohamed Abu-Farha
- Biochemistry and Molecular Biology Department, Dasman Diabetes Institute, Dasman, Kuwait
| | - Dinu Antony
- Genetics and Genomics Department, Dasman Diabetes Institute, Dasman, Kuwait
| | - Ashraf Al Madhoun
- Genetics and Genomics Department, Dasman Diabetes Institute, Dasman, Kuwait
| | - Chiara Bacchelli
- Genetics and Genomic Medicine, UCL Institute of Child Health, London, UK
| | - Fadi Alkayal
- Pancreatic Islet Biology & Transplantation Unit, Dasman Diabetes Institute, Dasman, Kuwait
| | - Irina AlKhairi
- Biochemistry and Molecular Biology Department, Dasman Diabetes Institute, Dasman, Kuwait
| | - Sumi John
- Integrative Informatics, Dasman Diabetes Institute, Dasman, Kuwait
| | - Mohamad Alomari
- Department of Pathology, Windsor Regional Hospital, Windsor, ON, Canada
| | - Phillip L Beales
- Genetics and Genomic Medicine, UCL Institute of Child Health, London, UK
| | - Osama Alsmadi
- Genetics and Genomics Department, Dasman Diabetes Institute, Dasman, Kuwait
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Unsworth AJ, Bye AP, Gibbins JM. Platelet-Derived Inhibitors of Platelet Activation. PLATELETS IN THROMBOTIC AND NON-THROMBOTIC DISORDERS 2017. [PMCID: PMC7123044 DOI: 10.1007/978-3-319-47462-5_37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Taylor KA, Pugh N. The contribution of zinc to platelet behaviour during haemostasis and thrombosis. Metallomics 2016; 8:144-55. [PMID: 26727074 DOI: 10.1039/c5mt00251f] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Platelets are the primary cellular determinants of haemostasis and pathological thrombus formation leading to myocardial infarction and stroke. Following vascular injury or atherosclerotic plaque rupture, platelets are recruited to sites of damage and undergo activation induced by a variety of soluble and/or insoluble agonists. Platelet activation is a multi-step process culminating in the formation of thrombi, which contribute to the haemostatic process. Zinc (Zn(2+)) is acknowledged as an important signalling molecule in a diverse range of cellular systems, however there is limited understanding of the influence of Zn(2+) on platelet behaviour during thrombus formation. This review evaluates the contributions of exogenous and intracellular Zn(2+) to platelet function and assesses the potential pathophysiological implications of Zn(2+) signalling. We also provide a speculative assessment of the mechanisms by which platelets could respond to changes in extracellular and intracellular Zn(2+) concentration.
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Affiliation(s)
- K A Taylor
- Department of Biomedical and Forensic Sciences, Faculty of Science and Technology, Anglia Ruskin University, Cambridge, CB1 1PT, UK.
| | - N Pugh
- Department of Biomedical and Forensic Sciences, Faculty of Science and Technology, Anglia Ruskin University, Cambridge, CB1 1PT, UK.
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Salva I, Batalha S, Maia R, Kjollerstrom P. Prolonged thrombocytopenia in a child with severe neonatal alloimmune reaction and Noonan syndrome. Platelets 2015; 27:381-2. [PMID: 26599469 DOI: 10.3109/09537104.2015.1107034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Fetomaternal alloimmune thrombocytopenia (FMAIT) caused by maternal antibodies is the leading cause of severe neonatal thrombocytopenia. A 1-month-old Caucasian girl was referred to our Hematology Clinic for persistent thrombocytopenia diagnosed after a bleeding episode. Diagnostic tests suggested FMAIT. Mild thrombocytopenia persisted for 18 months, and subsequent findings of dysmorphic facies, short stature and mild pulmonary stenosis led to the hypothesis of Noonan syndrome (NS), which was confirmed by genetic test. Other hematological abnormalities were excluded and she had no further bleeding episodes. This case illustrates the possibility of different diagnoses with the same clinical manifestations. The persistence of thrombocytopenia longer than expected associated with typical physical features led to the diagnosis of NS.
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Affiliation(s)
- Inês Salva
- a Department of Pediatric Hematology , Hospital de Dona Estefânia, Centro Hospitalar de Lisboa Central , Lisbon , Portugal
| | - Sara Batalha
- a Department of Pediatric Hematology , Hospital de Dona Estefânia, Centro Hospitalar de Lisboa Central , Lisbon , Portugal
| | - Raquel Maia
- a Department of Pediatric Hematology , Hospital de Dona Estefânia, Centro Hospitalar de Lisboa Central , Lisbon , Portugal
| | - Paula Kjollerstrom
- a Department of Pediatric Hematology , Hospital de Dona Estefânia, Centro Hospitalar de Lisboa Central , Lisbon , Portugal
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57
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SHP2 sails from physiology to pathology. Eur J Med Genet 2015; 58:509-25. [PMID: 26341048 DOI: 10.1016/j.ejmg.2015.08.005] [Citation(s) in RCA: 165] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 07/24/2015] [Accepted: 08/30/2015] [Indexed: 02/08/2023]
Abstract
Over the two past decades, mutations of the PTPN11 gene, encoding the ubiquitous protein tyrosine phosphatase SHP2 (SH2 domain-containing tyrosine phosphatase 2), have been identified as the causal factor of several developmental diseases (Noonan syndrome (NS), Noonan syndrome with multiple lentigines (NS-ML), and metachondromatosis), and malignancies (juvenile myelomonocytic leukemia). SHP2 plays essential physiological functions in organism development and homeostasis maintenance by regulating fundamental intracellular signaling pathways in response to a wide range of growth factors and hormones, notably the pleiotropic Ras/Mitogen-Activated Protein Kinase (MAPK) and the Phosphoinositide-3 Kinase (PI3K)/AKT cascades. Analysis of the biochemical impacts of PTPN11 mutations first identified both loss-of-function and gain-of-function mutations, as well as more subtle defects, highlighting the major pathophysiological consequences of SHP2 dysregulation. Then, functional genetic studies provided insights into the molecular dysregulations that link SHP2 mutants to the development of specific traits of the diseases, paving the way for the design of specific therapies for affected patients. In this review, we first provide an overview of SHP2's structure and regulation, then describe its molecular roles, notably its functions in modulating the Ras/MAPK and PI3K/AKT signaling pathways, and its physiological roles in organism development and homeostasis. In the second part, we describe the different PTPN11 mutation-associated pathologies and their clinical manifestations, with particular focus on the biochemical and signaling outcomes of NS and NS-ML-associated mutations, and on the recent advances regarding the pathophysiology of these diseases.
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58
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Tautz L, Senis YA, Oury C, Rahmouni S. Perspective: Tyrosine phosphatases as novel targets for antiplatelet therapy. Bioorg Med Chem 2015; 23:2786-97. [PMID: 25921264 PMCID: PMC4451376 DOI: 10.1016/j.bmc.2015.03.075] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Revised: 03/27/2015] [Accepted: 03/29/2015] [Indexed: 11/26/2022]
Abstract
Arterial thrombosis is the primary cause of most cases of myocardial infarction and stroke, the leading causes of death in the developed world. Platelets, highly specialized cells of the circulatory system, are key contributors to thrombotic events. Antiplatelet drugs, which prevent platelets from aggregating, have been very effective in reducing the mortality and morbidity of these conditions. However, approved antiplatelet therapies have adverse side effects, most notably the increased risk of bleeding. Moreover, there remains a considerable incidence of arterial thrombosis in a subset of patients receiving currently available drugs. Thus, there is a pressing medical need for novel antiplatelet agents with a more favorable safety profile and less patient resistance. The discovery of novel antiplatelet targets is the matter of intense ongoing research. Recent findings demonstrate the potential of targeting key signaling molecules, including kinases and phosphatases, to prevent platelet activation and aggregation. Here, we offer perspectives to targeting members of the protein tyrosine phosphatase (PTP) superfamily, a major class of enzymes in signal transduction. We give an overview of previously identified PTPs in platelet signaling, and discuss their potential as antiplatelet drug targets. We also introduce VHR (DUSP3), a PTP that we recently identified as a major player in platelet biology and thrombosis. We review our data on genetic deletion as well as pharmacological inhibition of VHR, providing proof-of-principle for a novel and potentially safer VHR-based antiplatelet therapy.
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Affiliation(s)
- Lutz Tautz
- NCI-Designated Cancer Center, Sanford-Burnham Medical Research Institute, 10901 N Torrey Pines Rd, La Jolla, CA 92037, USA.
| | - Yotis A Senis
- Centre for Cardiovascular Sciences, Institute of Biomedical Research, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Cécile Oury
- Laboratory of Thrombosis and Haemostasis, GIGA-Cardiovascular Sciences, University of Liège, Liège, Belgium
| | - Souad Rahmouni
- Immunology and Infectious Diseases Unit, GIGA-Signal Transduction, University of Liège, Liège, Belgium
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Abstract
Historically, platelet transfusion has proven a reliable way to treat patients suffering from thrombocytopenia or similar ailments. An undersupply of donors, however, has demanded alternative platelet sources. Scientists have therefore sought to recapitulate the biological events that convert hematopoietic stem cells into platelets in the laboratory. Such platelets have shown good function and potential for treatment. Yet the number manufactured ex vivo falls well short of clinical application. Part of the reason is the remarkable gaps in our understanding of the molecular mechanisms driving platelet formation. Using several stem cell sources, scientists have progressively clarified the chemical signaling and physical microenvironment that optimize ex vivo platelets and reconstituted them in synthetic environments. Key advances in cell reprogramming and the ability to propagate self-renewal have extended the lifetime of megakaryocytes to increase the pool of platelet progenitors.
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Affiliation(s)
- P Karagiannis
- Department of Clinical Application, Center for iPS Cell Research and Application, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - K Eto
- Department of Clinical Application, Center for iPS Cell Research and Application, Kyoto University, Sakyo-ku, Kyoto, Japan
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Favier R, Raslova H. Progress in understanding the diagnosis and molecular genetics of macrothrombocytopenias. Br J Haematol 2015; 170:626-39. [DOI: 10.1111/bjh.13478] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Remi Favier
- Institut National de la Santé et de la Recherche Médicale; U1170; Equipe Labellisée Ligue Contre le Cancer; Villejuif France
- Assistance Publique-Hôpitaux de Paris; Armand Trousseau Children Hospital; French Reference Center for Platelet Disorders; Haematological Laboratory; Paris France
| | - Hana Raslova
- Institut National de la Santé et de la Recherche Médicale; U1170; Equipe Labellisée Ligue Contre le Cancer; Villejuif France
- Faculté de Médecine; University Paris Saclay and University Paris-Sud 11; Le Kremlin-Bicêtre France
- Gustave Roussy; Villejuif France
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61
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Bekiaris V, Šedý JR, Ware CF. Mixing Signals: Molecular Turn Ons and Turn Offs for Innate γδ T-Cells. Front Immunol 2014; 5:654. [PMID: 25566265 PMCID: PMC4270187 DOI: 10.3389/fimmu.2014.00654] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 12/06/2014] [Indexed: 01/19/2023] Open
Abstract
Lymphocytes of the gamma delta (γδ) T-cell lineage are evolutionary conserved and although they express rearranged antigen-specific receptors, a large proportion respond as innate effectors. γδ T-cells are poised to combat infection by responding rapidly to cytokine stimuli similar to innate lymphoid cells. This potential to initiate strong inflammatory responses necessitates that inhibitory signals are balanced with activation signals. Here, we discuss some of the key mechanisms that regulate the development, activation, and inhibition of innate γδ T-cells in light of recent evidence that the inhibitory immunoglobulin-superfamily member B and T lymphocyte attenuator restricts their differentiation and effector function.
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Affiliation(s)
- Vasileios Bekiaris
- Infectious and Inflammatory Disease Center, Sanford-Burnham Medical Research Institute , La Jolla, CA , USA
| | - John R Šedý
- Infectious and Inflammatory Disease Center, Sanford-Burnham Medical Research Institute , La Jolla, CA , USA
| | - Carl F Ware
- Infectious and Inflammatory Disease Center, Sanford-Burnham Medical Research Institute , La Jolla, CA , USA
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Ye B, Li C, Yang Z, Wang Y, Hao J, Wang L, Li Y, Du Y, Hao L, Liu B, Wang S, Xia P, Huang G, Sun L, Tian Y, Fan Z. Cytosolic carboxypeptidase CCP6 is required for megakaryopoiesis by modulating Mad2 polyglutamylation. ACTA ACUST UNITED AC 2014; 211:2439-54. [PMID: 25332286 PMCID: PMC4235637 DOI: 10.1084/jem.20141123] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Ye et al. identify cytosolic carboxypeptidase CCP6 as a protein required for the regulation of bone marrow megakaryopoiesis in mice. The authors find that Mad2 (a core component of spindle checkpoint in mitosis) is a substrate of CCP6 in megakaryocytes and is polyglutamylated by proteins TTLL6 and TTLL4, subsequently affecting the activity of Aurora B kinase. Mad2 is thus additionally implicated in megakaryopoiesis regulation. Bone marrow progenitor cells develop into mature megakaryocytes (MKs) to produce platelets for hemostasis and other physiological functions. However, the molecular mechanisms underlying megakaryopoiesis are not completely defined. We show that cytosolic carboxypeptidase (CCP) 6 deficiency in mice causes enlarged spleens and increased platelet counts with underdeveloped MKs and dysfunctional platelets. The prominent phenotypes of CCP6 deficiency are different from those of CCP1-deficient mice. We found that CCP6 and tubulin tyrosine ligase-like family (TTLL) members TTLL4 and TTLL6 are highly expressed in MKs. We identify Mad2 (mitotic arrest deficient 2) as a novel substrate for CCP6 and not CCP1. Mad2 can be polyglutamylated by TTLL4 and TTLL6 to modulate the maturation of MKs. CCP6 deficiency causes hyperglutamylation of Mad2 to promote activation of Aurora B, leading to suppression of MK maturation. We reveal that Mad2 polyglutamylation plays a critical role in the regulation of megakaryopoiesis.
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Affiliation(s)
- Buqing Ye
- Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Chong Li
- Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhao Yang
- Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanying Wang
- Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Junfeng Hao
- Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Li Wang
- Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yi Li
- Department of Anesthesiology, Peking University Third Hospital, Beijing 100191, China
| | - Ying Du
- Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Lu Hao
- Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Benyu Liu
- Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Shuo Wang
- Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Pengyan Xia
- Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Guanling Huang
- Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Lei Sun
- Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yong Tian
- Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Zusen Fan
- Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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Rao AK, Freishtat RJ, Jalagadugula G, Singh A, Mao G, Wiles A, Cheung P, Boden G. Alterations in insulin-signaling and coagulation pathways in platelets during hyperglycemia-hyperinsulinemia in healthy non-diabetic subject. Thromb Res 2014; 134:704-10. [PMID: 25042561 PMCID: PMC4148207 DOI: 10.1016/j.thromres.2014.06.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 06/25/2014] [Accepted: 06/26/2014] [Indexed: 01/08/2023]
Abstract
INTRODUCTION Diabetes mellitus (DM) is a prothrombotic and proinflammatory state. Hyperglycemia (HG) is encountered even in patients without DM. We have shown that combined HG and hyperinsulinemia (HI) in healthy non-diabetic subjects increased circulating tissue factor (TF) and thrombin generation. To understand the changes in platelet and monocyte pathways induced by combined HG and HI in healthy non-diabetic state, we performed whole genome expression profiling of leukocyte-depleted platelets and monocytes before and after 24 hours of combined HG (glucose ~200mg/dL) and HI by glucose infusion clamp in a healthy non-diabetic subject. RESULTS We defined time-dependent differential mRNA expression (24 versus 0 hour fold change (FC) ≥ 2) common to platelets and monocytes. Ingenuity Pathways Analysis revealed alterations in canonical insulin receptor signaling and coagulation pathways. A preliminary group of 9 differentially expressed genes was selected for qRT-PCR confirmation. Platelet 24 hour sample was compared to the 0 hour sample plus 4 controls. Five transcripts in platelets and 6 in monocytes were confirmed. Platelet GSK3B and PTPN1 were upregulated, and STXBP4 was downregulated in insulin signaling, and F3 and TFPI were upregulated in coagulation pathways. Monocyte, PIK3C3, PTPN11 and TFPI were downregulated. Platelet GSKβ3 and PTPN11 protein and TF antigen in platelets and monocytes was increased. CONCLUSIONS Even in non-diabetic state, HG+HI for 24 hours induces changes in platelets and monocytes. They suggest downregulation of insulin signaling and upregulation of TF. Further studies are needed to elucidate cellular alterations leading to the prothrombotic and proinflammatory state in DM.
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Affiliation(s)
- A Koneti Rao
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, USA; Department of Medicine, Temple University School of Medicine, Philadelphia, PA, USA.
| | - Robert J Freishtat
- Division of Emergency Medicine, Children's National Medical Center, Washington, DC, USA
| | - Gauthami Jalagadugula
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, USA
| | - Anamika Singh
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, USA
| | - Guangfen Mao
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, USA
| | - Andrew Wiles
- Division of Emergency Medicine, Children's National Medical Center, Washington, DC, USA
| | - Peter Cheung
- General Clinical Research Center, Temple University School of Medicine, Philadelphia, PA, USA
| | - Guenther Boden
- Department of Medicine, Temple University School of Medicine, Philadelphia, PA, USA; General Clinical Research Center, Temple University School of Medicine, Philadelphia, PA, USA
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Abstract
Src family kinases (SFKs) play a central role in mediating the rapid response of platelets to vascular injury. They transmit activation signals from a diverse repertoire of platelet surface receptors, including the integrin αIIbβ3, the immunoreceptor tyrosine-based activation motif-containing collagen receptor complex GPVI-FcR γ-chain, and the von Willebrand factor receptor complex GPIb-IX-V, which are essential for thrombus growth and stability. Ligand-mediated clustering of these receptors triggers an increase in SFK activity and downstream tyrosine phosphorylation of enzymes, adaptors, and cytoskeletal proteins that collectively propagate the signal and coordinate platelet activation. A growing body of evidence has established that SFKs also contribute to Gq- and Gi-coupled receptor signaling that synergizes with primary activation signals to maximally activate platelets and render them prothrombotic. Interestingly, SFKs concomitantly activate inhibitory pathways that limit platelet activation and thrombus size. In this review, we discuss past discoveries that laid the foundation for this fundamental area of platelet signal transduction, recent progress in our understanding of the distinct and overlapping functions of SFKs in platelets, and new avenues of research into mechanisms of SFK regulation. We also highlight the thrombotic and hemostatic consequences of targeting platelet SFKs.
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Targeting protein tyrosine phosphatase SHP2 for therapeutic intervention. Future Med Chem 2014; 6:1423-37. [DOI: 10.4155/fmc.14.88] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Protein tyrosine phosphatases have been the focus of considerable research efforts aimed at developing novel therapeutics; however, these targets are often characterized as being ‘undruggable’ due to the challenge of achieving selectivity, potency and cell permeability. More recently, there has been renewed interest in developing inhibitors of the tyrosine phosphatase SHP2 (PTPN11) in the light of its broad role in cancer, specifically juvenile myelomonocytic leukemia, and recent studies that implicate SHP2 as a key factor in breast cancer progression. Recent significant advances in the field of SHP2 inhibitor development raise the question: are we on the verge of a new era of protein tyrosine phosphatase-directed therapeutics? This article critically appraises recent developments, assesses ongoing challenges and presents a perspective on possible future directions.
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Abstract
Murine paired immunoglobulin-like receptors B (PIRB), as the ortholog of human leukocyte immunoglobulin-like receptor B2 (LILRB2), is involved in a variety of biological functions. Here, we found that PIRB and LILRB2 were expressed in mouse and human platelets, respectively. PIRB intracellular domain deletion (PIRB-TM) mice had thrombocythemia and significantly higher proportions of megakaryocytes in bone marrow. Agonist-induced aggregation and spreading on immobilized fibrinogen were facilitated in PIRB-TM platelets. The rate of clot retraction in platelet-rich plasma containing PIRB-TM platelets was also increased. Characterization of signaling confirmed that PIRB associated with phosphatases Shp1/2 in platelets. The phosphorylation of Shp1/2 was significantly downregulated in PIRB-TM platelets stimulated with collagen-related peptide (CRP) or on spreading. The results further revealed that the phosphorylation levels of the linker for activation of T cells, SH2 domain-containing leukocyte protein of 76kDa, and phospholipase C were enhanced in PIRB-TM platelets stimulated with CRP. The phosphorylation levels of FAK Y397 and integrin β3 Y759 were also enhanced in PIRB-TM platelet spread on fibrinogen. The PIRB/LILRB2 ligand angiopoietin-like-protein 2 (ANGPTL2) was expressed and stored in platelet α-granules. ANGPTL2 inhibited agonist-induced platelet aggregation and spreading on fibrinogen. The data presented here reveal that PIRB and its ligand ANGPTL2 possess an antithrombotic function by suppressing collagen receptor glycoprotein VI and integrin αIIbβ3-mediated signaling.
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Machlus KR, Thon JN, Italiano JE. Interpreting the developmental dance of the megakaryocyte: a review of the cellular and molecular processes mediating platelet formation. Br J Haematol 2014; 165:227-36. [PMID: 24499183 DOI: 10.1111/bjh.12758] [Citation(s) in RCA: 157] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Platelets are essential for haemostasis, and thrombocytopenia (platelet counts <150 × 10(9) /l) is a major clinical problem encountered across a number of conditions, including immune thrombocytopenic purpura, myelodysplastic syndromes, chemotherapy, aplastic anaemia, human immunodeficiency virus infection, complications during pregnancy and delivery, and surgery. Circulating blood platelets are specialized cells that function to prevent bleeding and minimize blood vessel injury. Platelets circulate in their quiescent form, and upon stimulation, activate to release their granule contents and spread on the affected tissue to create a physical barrier that prevents blood loss. The current model of platelet formation states that large progenitor cells in the bone marrow, called megakaryocytes, release platelets by extending long, branching processes, designated proplatelets, into sinusoidal blood vessels. This review will focus on different factors that impact megakaryocyte development, proplatelet formation and platelet release. It will highlight recent studies on thrombopoeitin-dependent megakaryocyte maturation, endomitosis and granule formation, cytoskeletal contributions to proplatelet formation, the role of apoptosis, and terminal platelet formation and release.
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Affiliation(s)
- Kellie R Machlus
- Hematology Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
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68
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Senis YA. Protein-tyrosine phosphatases: a new frontier in platelet signal transduction. J Thromb Haemost 2013; 11:1800-13. [PMID: 24015866 DOI: 10.1111/jth.12359] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Indexed: 08/31/2023]
Abstract
Platelet activation must be tightly controlled in order to allow platelets to respond rapidly to vascular injury and prevent thrombosis from occurring. Protein-tyrosine phosphorylation is one of the main ways in which activation signals are transmitted in platelets. Although much is known about the protein-tyrosine kinases (PTKs) that initiate and propagate activation signals, relatively little is known about the protein-tyrosine phosphatases (PTPs) that modulate these signals in platelets. PTPs are a family of enzymes that dephosphorylate tyrosine residues in proteins and regulate signals transmitted within cells. PTPs have been implicated in a variety of pathological conditions, including cancer, diabetes and autoimmunity, but their functions in hemostasis and thrombosis remain largely undefined. Exciting new findings from a number of groups have revealed that PTPs are in fact critical regulators of platelet activation and thrombosis. The primary aim of this review is to highlight the unique and important functions of PTPs in regulating platelet activity. Establishing the functions of PTPs in platelets is essential to better understand the molecular basis of thrombosis and may lead to the development of improved antithrombotic therapies.
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Affiliation(s)
- Y A Senis
- Centre for Cardiovascular and Respiratory Sciences, Institute of Biomedical Research, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
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Abstract
In this issue of Blood, Mazharian and colleagues characterize Shp1 and Shp2 conditional knockout (KO) murine models, underscoring the role of these phosphatases not only on platelet function but also on megakaryocyte development and platelet counts and size.
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