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Zuliani JP, Yamanouye N, Gutiérrez JM, Teixeira C. PKC-α is involved in the signaling of phagocytosis induced by two snake venom secretory PLA 2S in macrophages. Toxicon 2024; 247:107824. [PMID: 38908525 DOI: 10.1016/j.toxicon.2024.107824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 06/18/2024] [Accepted: 06/19/2024] [Indexed: 06/24/2024]
Abstract
Phagocytosis, an essential process for host defense, requires the coordination of a variety of signaling reactions. MT-II, an enzymatically inactive Lys49 phospholipase A2 (PLA2) homolog, and MT-III, a catalytically-active Asp49 PLA2, are known to activate phagocytosis in macrophages. In this study, the signaling pathways mediating phagocytosis, focusing on protein kinases, were investigated. Macrophages from male Swiss mice peritoneum were obtained 96 h after intraperitoneal thioglycolate injection. Phagocytosis was evaluated using non-opsonized zymosan particles in the presence or absence of specific inhibitors, as well as PKC and PKC-α localization by confocal microscopy. Moreover, protein kinase C (PKC) activity was assessed by γP32 ATP in macrophages stimulated by both PLA2s. Data showed that both sPLA2s increased phagocytosis. Cytochalasin D, staurosporine/H7, wortmannin, and herbimycin, inhibitors of actin polymerization, PKC, phosphoinositide 3-kinase (PI3K), and protein tyrosine kinase (PTK), respectively, significantly reduced phagocytosis induced by both PLA2s. PKC activity was increased in macrophages stimulated by both PLA2s. Actin polymerization and talin were evidenced by immunofluorescence and talin was recruited 5 min after both PLA2s stimulation. PKC and PKC-α localization within the cell were increased after 60 min of MT-II and MT-III stimulation. These data suggest that the effect of both PLA2s depends on actin cytoskeleton rearrangements and the activation of PKC, PI3K, and PTK signaling events required for phagocytosis.
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Affiliation(s)
- Juliana Pavan Zuliani
- Laboratório de Farmacologia - Instituto Butantan, São Paulo, Brazil; Laboratório de Imunologia Celular Aplicada à Saúde, Fundação Oswaldo Cruz Rondônia/FIOCRUZ-RO, Porto Velho, RO, Brazil; Dep. Medicina, Universidade Federal de Rondônia, UNIR, Porto Velho, RO, Brazil.
| | - Norma Yamanouye
- Laboratório de Farmacologia - Instituto Butantan, São Paulo, Brazil.
| | - José María Gutiérrez
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica
| | - Catarina Teixeira
- Laboratório de Farmacologia - Instituto Butantan, São Paulo, Brazil.
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Prendecki M, Gulati K, Pisacano N, Pinheiro D, Bhatt T, Mawhin MA, Toulza F, Masuda ES, Cowburn A, Lodge KM, Tam FWK, Roufosse C, Pusey CD, McAdoo SP. Syk Activation in Circulating and Tissue Innate Immune Cells in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis. Arthritis Rheumatol 2023; 75:84-97. [PMID: 36428281 PMCID: PMC10099805 DOI: 10.1002/art.42321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 06/21/2022] [Accepted: 07/26/2022] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Syk is a cytoplasmic protein tyrosine kinase that plays a role in signaling via B cell and Fc receptors (FcR). FcR engagement and signaling via Syk is thought to be important in antineutrophil cytoplasm antibody (ANCA) IgG-mediated neutrophil activation. This study was undertaken to investigate the role of Syk in ANCA-induced myeloid cell activation and vasculitis pathogenesis. METHODS Phosphorylation of Syk in myeloid cells from healthy controls and ANCA-associated vasculitis (AAV) patients was analyzed using flow cytometry. The effect of Syk inhibition on myeloperoxidase (MPO)-ANCA IgG activation of cells was investigated using functional assays (interleukin-8 and reactive oxygen species production) and targeted gene analysis with NanoString. Total and phosphorylated Syk at sites of tissue inflammation in patients with AAV was assessed using immunohistochemistry and RNAscope in situ hybridization. RESULTS We identified increased phosphorylated Syk at critical activatory tyrosine residues in blood neutrophils and monocytes from patients with active AAV compared to patients with disease in remission or healthy controls. Syk was phosphorylated in vitro following MPO-ANCA IgG stimulation, and Syk inhibition was able to prevent ANCA-mediated cellular responses. Using targeted gene expression analysis, we identified up-regulation of FcR- and Syk-dependent signaling pathways following MPO-ANCA IgG stimulation. Finally, we showed that Syk is expressed and phosphorylated in tissue leukocytes at sites of organ inflammation in AAV. CONCLUSION These findings indicate that Syk plays a critical role in MPO-ANCA IgG-induced myeloid cell responses and that Syk is activated in circulating immune cells and tissue immune cells in AAV; therefore, Syk inhibition may be a potential therapeutic option.
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Affiliation(s)
- Maria Prendecki
- Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, and Imperial College Renal and Transplant Centre, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, UK
| | - Kavita Gulati
- Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, and Imperial College Renal and Transplant Centre, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, UK
| | - Noelle Pisacano
- National Heart and Lung Institute, Imperial College, London, UK
| | - Damilola Pinheiro
- Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, London, UK
| | - Tejal Bhatt
- Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, London, UK
| | - Marie-Anne Mawhin
- Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, London, UK
| | - Frederic Toulza
- Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, London, UK
| | | | - Andrew Cowburn
- National Heart and Lung Institute, Imperial College, London, UK
| | | | - Frederick W K Tam
- Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, and Imperial College Renal and Transplant Centre, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, UK
| | - Candice Roufosse
- Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, London, UK
| | - Charles D Pusey
- Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, and Imperial College Renal and Transplant Centre, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, UK
| | - Stephen P McAdoo
- Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, and Imperial College Renal and Transplant Centre, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, UK
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Walpole GFW, Grinstein S. Endocytosis and the internalization of pathogenic organisms: focus on phosphoinositides. F1000Res 2020; 9. [PMID: 32494357 PMCID: PMC7233180 DOI: 10.12688/f1000research.22393.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/07/2020] [Indexed: 12/18/2022] Open
Abstract
Despite their comparatively low abundance in biological membranes, phosphoinositides are key to the regulation of a diverse array of signaling pathways and direct membrane traffic. The role of phosphoinositides in the initiation and progression of endocytic pathways has been studied in considerable depth. Recent advances have revealed that distinct phosphoinositide species feature prominently in clathrin-dependent and -independent endocytosis as well as in phagocytosis and macropinocytosis. Moreover, a variety of intracellular and cell-associated pathogens have developed strategies to commandeer host cell phosphoinositide metabolism to gain entry and/or metabolic advantage, thereby promoting their survival and proliferation. Here, we briefly survey the current knowledge on the involvement of phosphoinositides in endocytosis, phagocytosis, and macropinocytosis and highlight several examples of molecular mimicry employed by pathogens to either “hitch a ride” on endocytic pathways endogenous to the host or create an entry path of their own.
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Affiliation(s)
- Glenn F W Walpole
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
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Zhou Y, Abraham S, Renna S, Edelstein LC, Dangelmaier CA, Tsygankov AY, Kunapuli SP, Bray PF, McKenzie SE. TULA-2 (T-Cell Ubiquitin Ligand-2) Inhibits the Platelet Fc Receptor for IgG IIA (FcγRIIA) Signaling Pathway and Heparin-Induced Thrombocytopenia in Mice. Arterioscler Thromb Vasc Biol 2016; 36:2315-2323. [PMID: 27765766 DOI: 10.1161/atvbaha.116.307979] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 10/04/2016] [Indexed: 12/19/2022]
Abstract
OBJECTIVE The objective of this study is to investigate the role of T-cell ubiquitin ligand-2 (TULA-2) in the platelet Fc receptor for IgG IIA (FcγRIIA) pathway and in the pathogenesis of heparin-induced thrombocytopenia (HIT). APPROACH AND RESULTS HIT is a life-threatening thrombotic disease in which IgG antibodies against the heparin-platelet factor 4 complex activate platelets via FcγRIIA. We reported previously differential expression of TULA-2 in human population was linked to FcγRIIA responsiveness. In this study, we investigated the role of TULA-2, a protein phosphatase, in the FcγRIIA pathway and HIT pathogenesis by crossing TULA-2-/- mice with transgenic FcγRIIA +/+ mice. Ablation of TULA-2 resulted in hyperphosphorylation of spleen tyrosine kinase, linker for the activation of T cells, and phospholipase Cγ2 in platelets via FcγRIIA activation. Platelet integrin activation, granule secretion, phosphatidylserine exposure, and aggregation were also enhanced in TULA-2-/- murine platelets. Compared with wild-type mice, TULA-2-/- mice showed aggravated antibody-mediated thrombocytopenia, augmented thrombin generation, and shortened tail bleeding time. In contrast, there was no significant difference between TULA-2-/- and TULA-2+/+ platelets in platelet spreading and clot retraction. Of note, heterozygous TULA-2+/- mice, whose platelets contained 50% as much protein as the TULA-2+/+ platelets, showed significantly increased platelet reactivity and more severe thrombocytopenia in vivo compared with TULA-2+/+ mice. CONCLUSIONS Together, the data demonstrate that not only the absence of TULA-2 but also the relative level of TULA-2 expression modulates FcγRIIA-mediated platelet reactivity and HIT in vivo. TULA-2 expression could be a valuable marker for HIT and inhibiting TULA-2 may serve as a potential therapy to reverse the bleeding adverse effect of anticoagulants.
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Affiliation(s)
- Yuhang Zhou
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Shaji Abraham
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Stephanie Renna
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Leonard C Edelstein
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Carol A Dangelmaier
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Alexander Y Tsygankov
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Satya P Kunapuli
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Paul F Bray
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Steven E McKenzie
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.).
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Arman M, Krauel K. Human platelet IgG Fc receptor FcγRIIA in immunity and thrombosis. J Thromb Haemost 2015; 13:893-908. [PMID: 25900780 DOI: 10.1111/jth.12905] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 03/10/2015] [Indexed: 01/23/2023]
Abstract
Beyond their prominent role in hemostasis and thrombosis, platelets are increasingly recognized as having immunologic functions. Supporting this, human platelets express FcγRIIA (CD32a), a low-affinity Fc receptor (FcR) for the constant region of IgG that recognizes immune complexes (ICs) and IgG-opsonized cells with high avidity. In leukocytes, FcγRIIA engagement initiates strong effector functions that are key for immune and inflammatory responses, including cytokine release, antibody-dependent cell-mediated killing of pathogens, and internalization of ICs. However, the physiologic relevance of platelet-expressed FcγRIIA has received little attention in previous reviews on FcRs. This article summarizes and discusses the available information on human platelet FcγRIIA. The importance of this receptor in heparin-induced thrombocytopenia, a prothrombotic adverse drug effect, is well documented. However, studies demonstrating platelet activation by IgG-opsonized bacteria point to the physiologic relevance of platelet FcγRIIA in immunity. In this context, platelet activation and secretion may facilitate both a direct antimicrobial function of platelets and crosstalk with other immune cells. Additionally, a role for platelet FcγRIIA in IgG-independent hemostasis and physiologic thrombosis, by means of amplifying integrin αII b β3 outside-in signaling, has also been proposed. Nonetheless, the thrombotic complications found in some infective and autoimmune diseases may result from unbalanced FcγRIIA-mediated platelet aggregation. Moreover, FcγRIIA is not expressed in mice, and thrombocytopenia and/or thrombotic events found after drug administration can only be recapitulated by the use of human FcγRIIA-transgenic mice. Altogether, the available data support a functional role for platelet FcγRIIA in health and disease, and emphasize the need for further investigation of this receptor.
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Affiliation(s)
- M Arman
- Centre for Cardiovascular Sciences, Institute of Biomedical Research, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - K Krauel
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
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Bacillus anthracis peptidoglycan activates human platelets through FcγRII and complement. Blood 2013; 122:571-9. [PMID: 23733338 DOI: 10.1182/blood-2013-02-486613] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Platelet activation frequently accompanies sepsis and contributes to the sepsis-associated vascular leakage and coagulation dysfunction. Our previous work has implicated peptidoglycan (PGN) as an agent causing systemic inflammation in gram-positive sepsis. We used flow cytometry and fluorescent microscopy to define the effects of PGN on the activation of human platelets. PGN induced platelet aggregation, expression of the activated form of integrin αIIbβ3, and exposure of phosphatidylserine (PS). These changes were dependent on immunoglobulin G and were attenuated by the Fcγ receptor IIa-blocking antibody IV.3, suggesting they are mediated by PGN-anti-PGN immune complexes signaling through Fcγ receptor IIa. PS exposure was not blocked by IV.3 but was sensitive to inhibitors of complement activation. PGN was a potent activator of the complement cascade in human plasma and caused deposition of C5b-9 on the platelet surface. Platelets with exposed PS had greatly accelerated prothrombinase activity. We conclude that PGN derived from gram-positive bacteria is a potent platelet agonist when complexed with anti-PGN antibody and could contribute to the coagulation dysfunction accompanying gram-positive infections.
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Grädler U, Schwarz D, Dresing V, Musil D, Bomke J, Frech M, Greiner H, Jäkel S, Rysiok T, Müller-Pompalla D, Wegener A. Structural and biophysical characterization of the Syk activation switch. J Mol Biol 2012; 425:309-33. [PMID: 23154170 DOI: 10.1016/j.jmb.2012.11.007] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 11/05/2012] [Accepted: 11/06/2012] [Indexed: 11/28/2022]
Abstract
Syk is an essential non-receptor tyrosine kinase in intracellular immunological signaling, and the control of Syk kinase function is considered as a valuable target for pharmacological intervention in autoimmune or inflammation diseases. Upon immune receptor stimulation, the kinase activity of Syk is regulated by binding of phosphorylated immune receptor tyrosine-based activating motifs (pITAMs) to the N-terminal tandem Src homology 2 (tSH2) domain and by autophosphorylation with consequences for the molecular structure of the Syk protein. Here, we present the first crystal structures of full-length Syk (fl-Syk) as wild type and as Y348F,Y352F mutant forms in complex with AMP-PNP revealing an autoinhibited conformation. The comparison with the crystal structure of the truncated Syk kinase domain in complex with AMP-PNP taken together with ligand binding studies by surface plasmon resonance (SPR) suggests conformational differences in the ATP sites of autoinhibited and activated Syk forms. This hypothesis was corroborated by studying the thermodynamic and kinetic interaction of three published Syk inhibitors with isothermal titration calorimetry and SPR, respectively. We further demonstrate the modulation of inhibitor binding affinities in the presence of pITAM and discuss the observed differences of thermodynamic and kinetic signatures. The functional relevance of pITAM binding to fl-Syk was confirmed by a strong stimulation of in vitro autophosphorylation. A structural feedback mechanism on the kinase domain upon pITAM binding to the tSH2 domain is discussed in analogy of the related family kinase ZAP-70 (Zeta-chain-associated protein kinase 70). Surprisingly, we observed distinct conformations of the tSH2 domain and the activation switch including Tyr348 and Tyr352 in the interdomain linker of Syk in comparison to ZAP-70.
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Affiliation(s)
- Ulrich Grädler
- Merck KGaA, Merck Serono Research, Small Molecule Platform/MIB, Frankfurter Str. 250, 64293 Darmstadt, Germany.
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Abstract
IgE and IgE receptors (FcεRI) are well-known inducers of allergy. We recently found in mice that active systemic anaphylaxis depends on IgG and IgG receptors (FcγRIIIA and FcγRIV) expressed by neutrophils, rather than on IgE and FcεRI expressed by mast cells and basophils. In humans, neutrophils, mast cells, basophils, and eosinophils do not express FcγRIIIA or FcγRIV, but FcγRIIA. We therefore investigated the possible role of FcγRIIA in allergy by generating novel FcγRIIA-transgenic mice, in which various models of allergic reactions induced by IgG could be studied. In mice, FcγRIIA was sufficient to trigger active and passive anaphylaxis, and airway inflammation in vivo. Blocking FcγRIIA in vivo abolished these reactions. We identified mast cells to be responsible for FcγRIIA-dependent passive cutaneous anaphylaxis, and monocytes/macrophages and neutrophils to be responsible for FcγRIIA-dependent passive systemic anaphylaxis. Supporting these findings, human mast cells, monocytes and neutrophils produced anaphylactogenic mediators after FcγRIIA engagement. IgG and FcγRIIA may therefore contribute to allergic and anaphylactic reactions in humans.
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McNicol A, Agpalza A, Jackson ECG, Hamzeh-Cognasse H, Garraud O, Cognasse F. Streptococcus sanguinis-induced cytokine release from platelets. J Thromb Haemost 2011; 9:2038-49. [PMID: 21824285 DOI: 10.1111/j.1538-7836.2011.04462.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND There is increasing evidence that both chronic and acute infections play a role in the development and progression of atherothrombotic disorders. One potential mechanism is the direct activation of platelets by bacteria. A wide range of bacterial species activate platelets through heterogeneous mechanisms. The oral micro-organism S. sanguinis stimulates platelet aggregation in vitro in a strain-dependent manner, although there are no reports of associated cytokine production. OBJECTIVE The aim of the present study was to determine whether platelet activation by S. sanguinis involved the release of pro-inflammatory and immune modulating factors, and whether activation was enhanced by epinephrine. METHODS AND RESULTS Four strains of S. sanguinis and one of S. gordonii stimulated the release of RANTES, PF4, sCD40L and PDGF-AB, whereas only one S. sanguinis strain caused the release of sCD62p. Epinephrine enhanced S. sanguinis-induced platelet aggregation and phosphorylation of phospholipase Cγ2 and Erk, but inhibited RANTES, PF4, sCD40L and PDGF-AB release. Wortmannin inhibited S. sanguinis-induced aggregation and release; however, only aggregation was partially reversed by epinephrine. CONCLUSIONS The present study demonstrates that platelets respond to S. sanguinis with both prothrombotic and pro-inflammatory/immune-modulating responses. Epinephrine, potentially released in response to infection and/or stress, can significantly enhance the prothrombotic response, thereby providing a putative link between bacteraemia and acute coronary events during stress. In contrast, epinephrine inhibited the pro-inflammatory/immune-modulating response by an undetermined mechanism.
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Affiliation(s)
- A McNicol
- Department of Oral Biology, University of Manitoba, Winnipeg, MB, Canada.
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Lu HK, Rentero C, Raftery MJ, Borges L, Bryant K, Tedla N. Leukocyte Ig-like receptor B4 (LILRB4) is a potent inhibitor of FcgammaRI-mediated monocyte activation via dephosphorylation of multiple kinases. J Biol Chem 2009; 284:34839-48. [PMID: 19833736 DOI: 10.1074/jbc.m109.035683] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The leukocyte immunoglobulin-like receptor (LILR) B4 belongs to a family of cell surface receptors that possesses cytoplasmic immunoreceptor tyrosine-based inhibitory motifs (ITIMs). LILRB4 is believed to down-regulate activation signals mediated by non-receptor tyrosine kinase cascades through the recruitment of SHP-1. However, the exact mechanisms of LILRB4-mediated inhibition are not fully elucidated. In this study, we demonstrate high level surface expression of LILRB4 on THP-1 cells and primary peripheral blood monocytes, which profoundly inhibited production of a key pro-inflammatory cytokine (TNFalpha) induced by FcgammaRI (CD64). We also report that LILRB4 aggregated to sites of activation upon co-ligation with CD64 and that this may enhance its inhibitory effects. Cross-linking of CD64 on THP-1 cells markedly increased phosphorylation of multiple proteins including tyrosine kinases and signaling molecules (Lck, Syk, LAT, and Erk), an adaptor protein that targets protein-tyrosine kinases for degradation (c-Cbl) and a protein involved in the formation of actin cytoskeletal rearrangement (alpha-actinin-4). Co-ligation of LILRB4 considerably reduced CD64-mediated phosphorylation of Lck, Syk, LAT, Erk, and c-Cbl but not alpha-actinin-4, suggesting selective inhibition of signaling molecules. Treatment of cells with a broad-spectrum phosphatase inhibitor, sodium pervanadate (SP), significantly reversed LILRB4-mediated inhibition of TNFalpha production and protein tyrosine phosphorylation. In comparison, treatment with an SHP-1 specific inhibitor, sodium stibogluconate (SS) has no effects indicating involvement of phosphatase(s) other than SHP-1 in LILRB4 signaling. Collectively, our data show LILRB4 is a potent inhibitor of monocytes activation. This may provide a new potential therapeutic strategy for inflammatory conditions characterized by excessive TNFalpha production.
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Affiliation(s)
- Hao Kim Lu
- Centre for Infection and Inflammation Research, University of New South Wales, Sydney, New South Wales 2052, Australia
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Gao C, Boylan B, Bougie D, Gill JC, Birenbaum J, Newman DK, Aster RH, Newman PJ. Eptifibatide-induced thrombocytopenia and thrombosis in humans require FcgammaRIIa and the integrin beta3 cytoplasmic domain. J Clin Invest 2009; 119:504-11. [PMID: 19197137 DOI: 10.1172/jci36745] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Accepted: 12/17/2008] [Indexed: 01/08/2023] Open
Abstract
Thrombocytopenia and thrombosis following treatment with the integrin alphaIIbbeta3 antagonist eptifibatide are rare complications caused by patient antibodies specific for ligand-occupied alphaIIbbeta3. Whether such antibodies induce platelet clearance by simple opsonization, by inducing mild platelet activation, or both is poorly understood. To gain insight into the mechanism by which eptifibatide-dependent antibodies initiate platelet clearance, we incubated normal human platelets with patient serum containing an alphaIIbbeta3-specific, eptifibatide-dependent antibody. We observed that in the presence of eptifibatide, patient IgG induced platelet secretion and aggregation as well as tyrosine phosphorylation of the integrin beta3 cytoplasmic domain, the platelet FcgammaRIIa Fc receptor, the protein-tyrosine kinase Syk, and phospholipase Cgamma2. Each activation event was inhibited by preincubation of the platelets with Fab fragments of the FcgammaRIIa-specific mAb IV.3 or with the Src family kinase inhibitor PP2. Patient serum plus eptifibatide did not, however, activate platelets from a patient with a variant form of Glanzmann thrombasthenia that expressed normal levels of FcgammaRIIa and the alphaIIbbeta3 complex but lacked most of the beta3 cytoplasmic domain. Taken together, these data suggest a novel mechanism whereby eptifibatide-dependent antibodies engage the integrin beta3 subunit such that FcgammaRIIa and its downstream signaling components become activated, resulting in thrombocytopenia and a predisposition to thrombosis.
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Affiliation(s)
- Cunji Gao
- Blood Research Institute, Blood Center of Wisconsin, 638 N. 18th Street, Milwaukee, WI 53201, USA
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Khandani A, Eng E, Jongstra-Bilen J, Schreiber AD, Douda D, Samavarchi-Tehrani P, Harrison RE. Microtubules regulate PI-3K activity and recruitment to the phagocytic cup during Fcgamma receptor-mediated phagocytosis in nonelicited macrophages. J Leukoc Biol 2007; 82:417-28. [PMID: 17502337 DOI: 10.1189/jlb.0706469] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Phagocytosis is a complex sequence of events involving coordinated remodeling of the plasma membrane with the underlying cytoskeleton. Although the role of the actin cytoskeleton is becoming increasingly elucidated, the role of microtubules (MTs) remains poorly understood. Here, we examine the role of MTs during FcgammaR-mediated phagocytosis in RAW264.7 mouse macrophages. We observe that MTs extend into the phagosomal cups. The MT-depolymerizing agents, colchicine and nocodazole, cause a sizeable reduction in phagocytosis of large particles in RAW264.7 cells. Phagocytosis in primed macrophages is unaffected by MT-depolymerizing agents. However, activation of macrophages coincides with an increased population of drug-stable MTs, which persist in functional phagocytic cups. Scanning electron microscopy analysis of unprimed macrophages reveals that pseudopod formation is reduced markedly following colchicine treatment, which is not a consequence of cell rounding. MT depolymerization in these cells does not affect particle binding, Syk, or Grb2-associated binder 2 recruitment or phosphotyrosine accumulation at the site of phagocytosis. Ras activation also proceeds normally in macrophages treated with colchicine. However, MT disruption causes a decrease in accumulation of AKT-pleckstrin homology-green fluorescent protein, a probe that binds to PI-3K products at the sites of particle binding. A corresponding decline in activated AKT is observed in colchicine-treated cells using immunoblotting with a phospho-specific-AKT (ser473) antibody. Furthermore, the translocation of the p85alpha regulatory subunit of PI-3K is reduced at the phagocytic cup in colchicine-treated cells. These findings suggest that MTs regulate the recruitment and localized activity of PI-3K during pseudopod formation.
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Affiliation(s)
- Arian Khandani
- Division of Life Sciences, University of Toronto at Scarborough, Toronto, Ontario, Canada
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14
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Kamen LA, Levinsohn J, Swanson JA. Differential association of phosphatidylinositol 3-kinase, SHIP-1, and PTEN with forming phagosomes. Mol Biol Cell 2007; 18:2463-72. [PMID: 17442886 PMCID: PMC1924803 DOI: 10.1091/mbc.e07-01-0061] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In macrophages, enzymes that synthesize or hydrolyze phosphatidylinositol (3,4,5)-trisphosphate [PI(3,4,5)P(3)] regulate Fcgamma receptor-mediated phagocytosis. Inhibition of phosphatidylinositol 3-kinase (PI3K) or overexpression of the lipid phosphatases phosphatase and tensin homologue (PTEN) and Src homology 2 domain-containing inositol phosphatase (SHIP-1), which hydrolyze PI(3,4,5)P(3) to phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4-bisphosphate [PI(3,4)P(2)], respectively, inhibit phagocytosis in macrophages. To examine how these enzymes regulate phagosome formation, the distributions of yellow fluorescent protein (YFP) chimeras of enzymes and pleckstrin homology (PH) domains specific for their substrates and products were analyzed quantitatively. PTEN-YFP did not localize to phagosomes, suggesting that PTEN regulates phagocytosis globally within the macrophage. SHIP1-YFP and p85-YFP were recruited to forming phagosomes. SHIP1-YFP sequestered to the leading edge and dissociated from phagocytic cups earlier than did p85-cyan fluorescent protein, indicating that SHIP-1 inhibitory activities are restricted to the early stages of phagocytosis. PH domain chimeras indicated that early during phagocytosis, PI(3,4,5)P(3) was slightly more abundant than PI(3,4)P(2) at the leading edge of the forming cup. These results support a model in which phagosomal PI3K generates PI(3,4,5)P(3) necessary for later stages of phagocytosis, PTEN determines whether those late stages can occur, and SHIP-1 regulates when and where they occur by transiently suppressing PI(3,4,5)P(3)-dependent activities necessary for completion of phagocytosis.
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Affiliation(s)
- Lynn A. Kamen
- *Department of Microbiology and Immunology and
- Program in Immunology, University of Michigan Medical School, Ann Arbor, MI 48109-0620
| | | | - Joel A. Swanson
- *Department of Microbiology and Immunology and
- Program in Immunology, University of Michigan Medical School, Ann Arbor, MI 48109-0620
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15
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16
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Vaillancourt M, Levasseur S, Tremblay ML, Marois L, Rollet-Labelle E, Naccache PH. The Src Homology 2-Containing Inositol 5-Phosphatase 1 (SHIP1) is involved in CD32a signaling in human neutrophils. Cell Signal 2006; 18:2022-32. [PMID: 16682172 DOI: 10.1016/j.cellsig.2006.03.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Revised: 03/22/2006] [Accepted: 03/23/2006] [Indexed: 01/05/2023]
Abstract
Phosphatidylinositol(3,4,5)triphosphate (PtdIns(3,4,5)P(3)) plays important signaling roles in immune cells, particularly in the control of activating pathways and of survival. It is formed by a family of phosphatidylinositol 3'-kinases (PI3Ks) which phosphorylate PtdIns(4,5)P(2) in vivo. In human neutrophils, the levels of PtdIns(3,4,5)P(3) increase rapidly at the leading edge of locomoting cells and at the base of the phagocytic cup during FcgammaR-mediated particle ingestion. Even though these, and other, data indicate that PtdIns(3,4,5)P(3) is involved in the control of chemotaxis and phagocytosis in human neutrophils, the mechanisms that regulate its levels have yet to be fully elucidated in these cells. We evaluated the potential implication of SHIP1 and PTEN, two lipid phosphatases that utilize PtdIns(3,4,5)P(3) as substrate, in the signaling pathways called upon in response to CD32a cross-linking. We observed that the cross-linking of CD32a resulted in a transient accumulation of PtdIns(3,4,5)P(3). CD32a cross-linking also induced the tyrosine phosphorylation of SHIP1, its translocation to the plasma membrane and its co-immunoprecipitation with CD32a. CD32a cross-linking had no effect on the level of serine/threonine phosphorylation of PTEN and did not stimulate its translocation to the plasma membrane. PP2, a Src kinase inhibitor, inhibited the tyrosine phosphorylation of SHIP1 as well as its translocation to the plasma membrane. Wortmannin, a PI3K inhibitor, had no effect on either of these two indices of activation of SHIP1. Our results indicate that SHIP1 is involved, in a Src kinase-dependent manner, in the early signaling events observed upon the cross-linking of CD32a in human neutrophils.
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Affiliation(s)
- Myriam Vaillancourt
- Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du CHUL, Room T1-49, 2705, Boulevard Laurier and Department of Medicine, Faculty of Medicine, Laval University, Sainte-Foy, QC, Canada
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17
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Ganesan LP, Joshi T, Fang H, Kutala VK, Roda J, Trotta R, Lehman A, Kuppusamy P, Byrd JC, Carson WE, Caligiuri MA, Tridandapani S. FcgammaR-induced production of superoxide and inflammatory cytokines is differentially regulated by SHIP through its influence on PI3K and/or Ras/Erk pathways. Blood 2006; 108:718-25. [PMID: 16543474 PMCID: PMC1895481 DOI: 10.1182/blood-2005-09-3889] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Phagocytosis of IgG-coated particles via FcgammaR is accompanied by the generation of superoxide and inflammatory cytokines, which can cause collateral tissue damage in the absence of regulation. Molecular mechanisms regulating these phagocytosis-associated events are not known. SHIP is an inositol phosphatase that downregulates PI3K-mediated activation events. Here, we have examined the role of SHIP in FcgammaR-induced production of superoxide and inflammatory cytokines. We report that primary SHIP-deficient bone marrow macrophages produce elevated levels of superoxide upon FcgammaR clustering. Analysis of the molecular mechanism revealed that SHIP regulates upstream Rac-GTP binding, an obligatory event for superoxide production. Likewise, SHIP-deficient macrophages displayed enhanced IL-1beta and IL-6 production in response to FcgammaR clustering. Interestingly, whereas IL-6 production required activation of both PI3K and Ras/Erk pathways, IL-1beta production was dependent only on Ras/Erk activation, suggesting that SHIP may also regulate the Ras/Erk pathway in macrophages. Consistently, SHIP-deficient macrophages displayed enhanced activation of Erk upon FcgammaR clustering. Inhibition of Ras/Erk or PI3K suppressed the enhanced production of IL-6 in SHIP-deficient macrophages. In contrast, inhibition of Ras/Erk, but not PI3K, suppressed IL-1beta production in these cells. Together, these data demonstrate that SHIP regulates phagocytosis-associated events through the inhibition of PI3K and Ras/Erk pathways.
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Affiliation(s)
- Latha P Ganesan
- Department of Internal Medicine, The Ohio State University Biochemistry Program, Columbus, USA
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18
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Selheim F, Herfindal L, Martins R, Vasconcelos V, Døskeland SO. Neuro-apoptogenic and blood platelet targeting toxins in benthic marine cyanobacteria from the Portuguese coast. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2005; 74:294-306. [PMID: 16039729 DOI: 10.1016/j.aquatox.2005.06.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2005] [Revised: 06/07/2005] [Accepted: 06/11/2005] [Indexed: 05/03/2023]
Abstract
Six strains of marine cyanobacteria, of which five benthic, were isolated from an area of the Portuguese coast with no known apparent toxic microbial bloom. Five strains were lethal for mice. Four of them produced lethargy and four lead to bleeding. One of the toxic strains was from a genus (Aphanothece) not previously associated with toxin production. Extracts from four isolates induced SH-SY5Y-neuroblastoma cell apoptosis without affecting the viability of hepatocytes, NRK kidney cells, or fibroblasts. Aqueous extract from four isolates inhibited thrombin-induced blood platelet activation, with decreased P-selectin expression, platelet aggregation and shedding of platelet-derived micro-vesicles. Curiously, platelets treated with organic extracts from two of the cyanobacterial strains formed platelet micro-vesicles, expressed P-selectin on the surface and showed a distinct phosphotyrosine protein pattern, but failed to aggregate. We conclude that low-abundance marine cyanobacteria growing at low rates may be an important source for novel toxins that may be useful to dissect mammalian signalling pathways of apoptosis and platelet function.
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Affiliation(s)
- Frode Selheim
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway
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19
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Ai J, Maturu A, Johnson W, Wang Y, Marsh CB, Tridandapani S. The inositol phosphatase SHIP-2 down-regulates FcgammaR-mediated phagocytosis in murine macrophages independently of SHIP-1. Blood 2005; 107:813-20. [PMID: 16179375 PMCID: PMC1895625 DOI: 10.1182/blood-2005-05-1841] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
FcgammaR-mediated phagocytosis of IgG-coated particles is a complex process involving the activation of multiple signaling enzymes and is regulated by the inositol phosphatases PTEN (phosphatase and tensin homolog deleted on chromosome 10) and SHIP-1 (Src homology [SH2] domain-containing inositol phosphatase). In a recent study we have demonstrated that SHIP-2, an inositol phosphatase with high-level homology to SHIP-1, is involved in FcgammaR signaling. However, it is not known whether SHIP-2 plays a role in modulating phagocytosis. In this study we have analyzed the role of SHIP-2 in FcgammaR-mediated phagocytosis using independent cell models that allow for manipulation of SHIP-2 function without influencing the highly homologous SHIP-1. We present evidence that SHIP-2 translocates to the site of phagocytosis and down-regulates FcgammaR-mediated phagocytosis. Our data indicate that SHIP-2 must contain both the N-terminal SH2 domain and the C-terminal proline-rich domain to mediate its inhibitory effect. The effect of SHIP-2 is independent of SHIP-1, as overexpression of dominant-negative SHIP-2 in SHIP-1-deficient primary macrophages resulted in enhanced phagocytic efficiency. Likewise, specific knockdown of SHIP-2 expression using siRNA resulted in enhanced phagocytosis. Finally, analysis of the molecular mechanism of SHIP-2 down-regulation of phagocytosis revealed that SHIP-2 down-regulates upstream activation of Rac. Thus, we conclude that SHIP-2 is a novel negative regulator of FcgammaR-mediated phagocytosis independent of SHIP-1.
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Affiliation(s)
- Jing Ai
- Molecular, Cellular, and Developmental Biology Program, The Ohio State University, USA
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20
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Gachet C. The platelet P2 receptors as molecular targets for old and new antiplatelet drugs. Pharmacol Ther 2005; 108:180-92. [PMID: 15955565 DOI: 10.1016/j.pharmthera.2005.03.009] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2005] [Accepted: 03/24/2005] [Indexed: 12/15/2022]
Abstract
Platelet activation by ADP and ATP plays a crucial role in haemostasis and thrombosis, and their so-called P2 receptors are potential targets for antithrombotic drugs. The ATP-gated channel P2X1 and the 2 G protein-coupled P2Y1 and P2Y12 ADP receptors selectively contribute to platelet aggregation. The P2Y1 receptor is responsible for ADP-induced shape change and weak and transient aggregation, while the P2Y12 receptor is responsible for the completion and amplification of the response to ADP and to all platelet agonists, including thromboxane A2 (TXA2), thrombin, and collagen. The P2X1 receptor is involved in platelet shape change and in activation by collagen under shear conditions. Due to its central role in the formation and stabilization of a thrombus, the P2Y12 receptor is a well-established target of antithrombotic drugs like ticlopidine or clopidogrel, which have proved efficacy in many clinical trials and experimental models of thrombosis. Competitive P2Y12 antagonists have also been shown to be effective in experimental thrombosis as well as in several clinical trials. Studies in P2Y1 and P2X1 knockout mice and experimental thrombosis models using selective P2Y1 and P2X1 antagonists have shown that, depending on the conditions, these receptors could also be potential targets for new antithrombotic drugs.
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Affiliation(s)
- Christian Gachet
- INSERM U.311, Etablissement Français du Sang-Alsace, 10 rue Spielmann, B.P. No. 36, 67065 Strasbourg Cedex, France.
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21
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Rollet-Labelle E, Marois S, Barbeau K, Malawista SE, Naccache PH. Recruitment of the cross-linked opsonic receptor CD32A (FcgammaRIIA) to high-density detergent-resistant membrane domains in human neutrophils. Biochem J 2004; 381:919-28. [PMID: 15130090 PMCID: PMC1133904 DOI: 10.1042/bj20031808] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2003] [Revised: 04/05/2004] [Accepted: 05/06/2004] [Indexed: 02/02/2023]
Abstract
We have previously shown that CD32A (or FcgammaRIIA), one of the main opsonin receptors, was rapidly insolubilized and degraded in intact neutrophils after its cross-linking. In view of these experimental difficulties, the early signalling steps in response to CD32A activation were studied in purified plasma membranes of neutrophils. After CD32A cross-linking in these fractions, the tyrosine phosphorylation of two major substrates, the receptor itself and the tyrosine kinase Syk, was observed. Phosphorylation of these two proteins was observed only in the presence of orthovanadate, indicating the presence, in the membranes, of one or more tyrosine phosphatases that maintain CD32A dephosphorylation. The tyrosine phosphorylation of these two proteins was inhibited by the Src kinase inhibitor, 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2). The ligation of CD32A led to its recruitment to a previously uncharacterized subset of high-density flotillin-1-positive DRMs (detergent-resistant membranes). The changes in the solubility properties of CD32A were observed in the absence of added ATP; therefore, they were probably not secondary to the tyrosine phosphorylation of the receptor, rather they preceded it. Src kinases as well as Syk were constitutively present in DRMs of high and low density and no evident changes in their distribution were detected after cross-linking of CD32A. Pretreatment of plasma membranes with methyl-beta-cyclodextrin did not inhibit the recruitment of CD32A to DRMs, although it led to the loss of the Src kinase Lyn from these fractions. In addition, methyl-beta-cyclodextrin inhibited the tyrosine phosphorylation of CD32A and Syk induced by cross-linking of CD32A. This membrane model allowed us to observe a movement of CD32A from detergent-soluble regions of the membranes to DRMs, where it joined Src kinases and Syk and became tyrosine-phosphorylated.
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Affiliation(s)
- Emmanuelle Rollet-Labelle
- Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du CHUL and Department of Medicine, Faculty of Medicine, Laval University, Sainte-Foy, QC, Canada G1V 4G2.
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22
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Ganesan LP, Wei G, Pengal RA, Moldovan L, Moldovan N, Ostrowski MC, Tridandapani S. The Serine/Threonine Kinase Akt Promotes Fcγ Receptor-mediated Phagocytosis in Murine Macrophages through the Activation of p70S6 Kinase. J Biol Chem 2004; 279:54416-25. [PMID: 15485887 DOI: 10.1074/jbc.m408188200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Fc gamma receptor (Fc gamma R) clustering by immune complexes activates multiple signaling pathways leading to phagocytosis. We and others have previously reported that Akt is phosphorylated in response to Fc gamma R clustering. However, the functional consequence of Akt activation by Fc gamma R is not known. Using Raw 264.7 macrophage cells transfected to overexpress either constitutively active myristoylated (Myr)-Akt or a dominant-negative CAAX-Akt and bone marrow macrophages (BMMs) from wild-type and transgenic mice expressing macrophage-specific Myr-Akt, we analyzed the function of Akt in phagocytosis. We report that overexpression of Myr-Akt resulted in significant increase in phagocytic efficiency, whereas CAAX-Akt down-regulated phagocytosis in Raw 264.7 cells. Likewise BMMs expressing Myr-Akt displayed enhanced phagocytic ability. Analyzing the downstream effectors of Akt, we demonstrate that p70S6 kinase is constitutively phosphorylated in Myr-Akt-expressing BMMs. p70S6 kinase is reported to influence actin cytoskeleton and cell migration, suggesting that Akt may influence phagocytosis through the activation of p70S6 kinase. Consistent with this, overexpression of either wild-type or constitutively active but not a kinase-inactive p70S6 kinase in Raw 264.7 cells significantly enhanced phagocytosis. Likewise suppression of p70S6 kinase with rapamycin down-regulated phagocytic efficiency conferred by the expression of constitutively active Akt. These findings demonstrate a novel role for Akt in phagocytosis through the activation of p70S6 kinase.
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Affiliation(s)
- Latha P Ganesan
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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23
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Moon KD, Post CB, Durden DL, Zhou Q, De P, Harrison ML, Geahlen RL. Molecular basis for a direct interaction between the Syk protein-tyrosine kinase and phosphoinositide 3-kinase. J Biol Chem 2004; 280:1543-51. [PMID: 15536084 DOI: 10.1074/jbc.m407805200] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
After engagement of the B cell receptor for antigen, the Syk protein-tyrosine kinase becomes phosphorylated on multiple tyrosines, some of which serve as docking sites for downstream effectors with SH2 or other phosphotyrosine binding domains. The most frequently identified binding partner for catalytically active Syk identified in a yeast two-hybrid screen was the p85 regulatory subunit of phosphoinositide 3-kinase. The C-terminal SH2 domain of p85 was sufficient for mediating an interaction with tyrosine-phosphorylated Syk. Interestingly, this domain interacted with Syk at phosphotyrosine 317, a site phosphorylated in trans by the Src family kinase, Lyn, and identified previously as a binding site for c-Cbl. This site interacted preferentially with the p85 C-terminal SH2 domain compared with the c-Cbl tyrosine kinase binding domain. Molecular modeling studies showed a good fit between the p85 SH2 domain and a peptide containing phosphotyrosine 317. Tyr-317 was found to be essential for Syk to support phagocytosis mediated by FcgammaRIIA receptors expressed in a heterologous system. These studies establish a new type of p85 binding site that can exist on proteins that serve as substrates for Src family kinases and provide a molecular explanation for observations on direct interactions between Syk and phosphoinositide 3-kinase.
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Affiliation(s)
- Kyung D Moon
- Department of Medicinal Chemistry and Molecular Pharmacology and the Purdue Cancer Center, Purdue University, West Lafayette, Indiana 47907, USA
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24
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Kumaran S, Grucza RA, Waksman G. The tandem Src homology 2 domain of the Syk kinase: a molecular device that adapts to interphosphotyrosine distances. Proc Natl Acad Sci U S A 2003; 100:14828-33. [PMID: 14657388 PMCID: PMC299811 DOI: 10.1073/pnas.2432867100] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2003] [Indexed: 11/18/2022] Open
Abstract
Conformational flexibility is important for protein function. However, information on the range of conformations accessible to macromolecules in the unbound state is often difficult to obtain. By using the model system of the tandem Src homology 2 domain (i.e., two adjacent Src homology 2 domains) of the Syk kinase, we report a method combining calorimetric and crystallographic measurements that reveals the preexistence of a conformational equilibrium in the unbound state, and that shows that this equilibrium is crucial for function.
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MESH Headings
- Amino Acid Sequence
- Antigens, CD/chemistry
- Calorimetry
- Crystallography, X-Ray
- Dithiothreitol/pharmacology
- Enzyme Precursors/chemistry
- Humans
- Intracellular Signaling Peptides and Proteins
- Kinetics
- Ligands
- Models, Chemical
- Models, Molecular
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Peptides/chemistry
- Phosphotyrosine/chemistry
- Protein Binding
- Protein Conformation
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Protein-Tyrosine Kinases/chemistry
- Receptors, IgG/chemistry
- Sequence Homology, Amino Acid
- Spectrometry, Fluorescence
- Syk Kinase
- Thermodynamics
- src Homology Domains
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Affiliation(s)
- Sangaralingam Kumaran
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 South Euclid Avenue, Saint Louis, MO 63110, USA
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25
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Ragab A, Bodin S, Viala C, Chap H, Payrastre B, Ragab-Thomas J. The tyrosine phosphatase 1B regulates linker for activation of T-cell phosphorylation and platelet aggregation upon FcgammaRIIa cross-linking. J Biol Chem 2003; 278:40923-32. [PMID: 12857726 DOI: 10.1074/jbc.m303602200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Human platelets express the receptor for immunoglobulin G, FcgammaRIIa, that triggers cell aggregation upon interaction with immune complexes. Here, we report that the rapid tyrosine phosphorylation of the Linker for Activation of T-cell (LAT) in human platelets stimulated by FcgammaRIIa cross-linking was followed by its complete dephosphorylation in an alphaIIb/beta3 integrin-dependent manner. Concomitant to LAT dephosphorylation, the protein tyrosine phosphatase 1B (PTP1B) was activated through a mechanism involving its proteolysis by calpains downstream of integrins. Both PTP1B and LAT were associated with the actin cytoskeleton complex formed during platelet aggregation. Moreover, phospho-LAT appeared as a good substrate of activated PTP1B in vitro and these two proteins interacted upon platelet activation by FcgammaRIIa cross-linking. The permeant substrate-trapping PTP1B (TAT-PTP1B D181A) partly inhibited LAT dephosphorylation in human platelets, strongly suggesting that this tyrosine phosphatase was involved in this regulatory pathway. Using a pharmacological inhibitor, we provide evidence that PTP1B activation and LAT dephosphorylation processes were required for irreversible platelet aggregation. Altogether, our results demonstrate that PTP1B plays an important role in the integrin-mediated dephosphorylation of LAT in human platelets and is involved in the control of irreversible aggregation upon FcgammaRIIa stimulation.
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Affiliation(s)
- Ashraf Ragab
- INSERM U563, Centre de Physiopathologie de Toulouse-Purpan, Institut Fédératif de Recherche 30, Universite Paul Sabatier, Hôpital Purpan, 31059 Toulouse Cedex, France
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26
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Barkalow KL, Falet H, Italiano JE, van Vugt A, Carpenter CL, Schreiber AD, Hartwig JH. Role for phosphoinositide 3-kinase in Fc gamma RIIA-induced platelet shape change. Am J Physiol Cell Physiol 2003; 285:C797-805. [PMID: 12788695 DOI: 10.1152/ajpcell.00165.2003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Platelets transform from disks to irregular spheres, grow filopodia, form ruffles, and spread on surfaces coated with anti-Fc gamma RIIA antibody. Fc gamma RIIA cross-linking leads to a tenfold increase in actin filament barbed end exposure and robust actin assembly. Activation of the small GTPases Rac and Cdc42 follows Fc gamma RIIA cross-linking. Shape change, actin filament barbed end exposure, and quantifiable actin assembly require phosphoinositide 3-kinase (PI3-kinase) activity and a rise in intracellular calcium. PI3-kinase inhibition blocks activation of Rac, but not of Cdc42, and diminishes the association of Arp2/3 complex and CapZ with polymerized actin. Furthermore, addition of constitutively active D-3 phosphorylated polyphosphoinositides or recombinant PI3-kinase subunits to octylglucoside-permeabilized platelets elicits actin filament barbed end exposure by releasing gelsolin and CapZ from the cytoskeleton. Our findings place PI3-kinase activity upstream of Rac, gelsolin, and Arp2/3 complex activation induced by Fc gamma RIIA and clearly distinguish the Fc gamma RIIA signaling pathway to actin filament assembly from the thrombin receptor protease-activated receptor (PAR)-1 pathway.
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Affiliation(s)
- Kurt L Barkalow
- Division of Hematology, Brigham and Women's Hospital, Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
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27
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Ganesan LP, Fang H, Marsh CB, Tridandapani S. The protein-tyrosine phosphatase SHP-1 associates with the phosphorylated immunoreceptor tyrosine-based activation motif of Fc gamma RIIa to modulate signaling events in myeloid cells. J Biol Chem 2003; 278:35710-7. [PMID: 12832410 DOI: 10.1074/jbc.m305078200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fc gamma RIIa is a low affinity IgG receptor uniquely expressed in human cells that promotes phagocytosis of immune complexes and induces inflammatory cytokine gene transcription. Recent studies have revealed that phagocytosis initiated by Fc gamma RIIa is tightly controlled by the inositol phosphatase SHIP-1, and the protein-tyrosine phosphatase SHP-1. Whereas the molecular nature of SHIP-1 involvement with Fc gamma RIIa has been well studied, it is not clear how SHP-1 is activated by Fc gamma RIIa to mediate its regulatory effect. Here we report that Fc gamma RIIa clustering induces SHP-1 phosphatase activity in THP-1 cells. Using synthetic phosphopeptides, and stable transfectants expressing immunoreceptor tyrosine-based activation motif (ITAM) tyrosine mutants of Fc gamma RIIa, we demonstrate that SHP-1 associates with the phosphorylated amino-terminal ITAM tyrosine of Fc gamma RIIa, whereas the tyrosine kinase Syk associates with the carboxyl-terminal ITAM tyrosine. Association of SHP-1 with Fc gamma RIIa ITAM appears to suppress total cellular tyrosine phosphorylation. Furthermore, Fc gamma RIIa clustering results in the association of SHP-1 with key signaling molecules such as Syk, p85 subunit of PtdIns 3-kinase, and p62dok, suggesting that these molecules may be substrates of SHP-1 in this system. Finally, overexpression of wild-type SHP-1 but not catalytically deficient SHP-1 led to a down-regulation of NF kappa B-dependent gene transcription in THP-1 cells activated by clustering Fc gamma RIIa.
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MESH Headings
- Antigens, CD/chemistry
- Antigens, CD/genetics
- Antigens, CD/isolation & purification
- Antigens, CD/physiology
- Cell Line
- Humans
- Intracellular Signaling Peptides and Proteins
- Kinetics
- Mutagenesis, Site-Directed
- Phosphorylation
- Protein Tyrosine Phosphatase, Non-Receptor Type 6
- Protein Tyrosine Phosphatases/chemistry
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases/metabolism
- Receptors, IgG/chemistry
- Receptors, IgG/genetics
- Receptors, IgG/isolation & purification
- Receptors, IgG/physiology
- Recombinant Proteins/chemistry
- Recombinant Proteins/metabolism
- Signal Transduction/physiology
- Transfection
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Affiliation(s)
- Latha P Ganesan
- Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, The Dorothy M. Davis Heart and Lung Institute, and Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio 43210, USA
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28
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Pengal RA, Ganesan LP, Fang H, Marsh CB, Anderson CL, Tridandapani S. SHIP-2 inositol phosphatase is inducibly expressed in human monocytes and serves to regulate Fcgamma receptor-mediated signaling. J Biol Chem 2003; 278:22657-63. [PMID: 12690104 DOI: 10.1074/jbc.m302907200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
SHIP-2, a recently identified inositol 5'-phosphatase, shares high level homology with SHIP-1. Although the role of SHIP-1 has been extensively studied, the role of SHIP-2 in myeloid cell functions is not known. Here, we have analyzed the expression patterns, molecular mechanism of activation, and function of SHIP-2 in human myeloid cell Fcgamma receptor (FcgammaR) signaling. We report that SHIP-2 is expressed in transformed myeloid cells and in primary macrophages, but not in peripheral blood monocytes. Treatment of peripheral blood monocytes with bacterial lipopolysaccharide induced expression of SHIP-2 in a dose-dependent manner. FcgammaRIIa clustering in THP-1 cells induced SHIP-2 tyrosine phosphorylation, suggesting a role for SHIP-2 in modulating FcgammaR-mediated function. Consistent with this notion, overexpression of wild-type SHIP-2 (but not catalytically deficient SHIP-2) in THP-1 cells almost completely abrogated NFkappaB-mediated gene transcription in response to FcgammaRIIa clustering. Furthermore, FcgammaRIIa-induced Akt activation was blocked by wild-type SHIP-2, but not by a catalytically deficient mutant of SHIP-2. Additional experiments analyzing the molecular mechanism of SHIP-2 induction by FcgammaRIIa revealed that SHIP-2 associated with the phosphorylated FcgammaRIIa immunoreceptor tyrosine-based activation motif via the SHIP-2 SH2 domain. Thus, an SH2 domain mutant of SHIP-2 failed to associate with FcgammaRIIa or to become tyrosine-phosphorylated upon FcgammaRIIa clustering. Finally, we also demonstrate that SHIP-2 phosphorylation was induced by FcgammaRI clustering in THP-1 cells. These findings unravel a novel level of regulation of FcgammaR-mediated activation of human myeloid cells by the expression and function of the inositol phosphatase SHIP-2.
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Affiliation(s)
- Ruma A Pengal
- Molecular, Cellular, and Developmental Biology Program, Dorothy M. Davis Heart and Lung Institute, James Cancer Hospital, Ohio State University, Columbus 43210, USA
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29
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Calverley DC, Hacker MR, Loda KA, Brass E, Buchanan TA, Tsao-Wei DD, Groshen S. Increased platelet Fc receptor expression as a potential contributing cause of platelet hypersensitivity to collagen in diabetes mellitus. Br J Haematol 2003; 121:139-42. [PMID: 12670344 DOI: 10.1046/j.1365-2141.2003.04233.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Recent clinical and laboratory observations support a potential role for the platelet FcgammaRIIA receptor (FcR) in collagen-mediated platelet activation associated with arterial thrombosis. Stable age- and sex-independent variation in receptor expression exists. Flow cytometry showed that 100 diabetes patients had increased mean platelet FcR expression levels compared with 201 non-diabetes patients (P < 0.001). Aggregation studies following FcR cross-linking supported a receptor role in increased activation of diabetes platelets after collagen stimulation (P = 0.018). Immunoprecipitation of collagen-stimulated and FcR-crosslinked platelets demonstrated enhanced levels of tyrosine-phosphorylated Syk in diabetic platelets. Increased platelet FcR-mediated sensitivity to collagen may contribute to cardiovascular morbidity and mortality in diabetes.
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Affiliation(s)
- David C Calverley
- Divisions of Hematology and Medical Oncology, University of Colorado Health Science Center, 4200 East 9th Avenue, Denver, CO 80262, USA.
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30
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Nakamura K, Malykhin A, Coggeshall KM. The Src homology 2 domain-containing inositol 5-phosphatase negatively regulates Fcgamma receptor-mediated phagocytosis through immunoreceptor tyrosine-based activation motif-bearing phagocytic receptors. Blood 2002; 100:3374-82. [PMID: 12384440 DOI: 10.1182/blood-2002-03-0787] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Molecular mechanisms by which the Src homology 2 domain-containing inositol 5-phosphatase (SHIP) negatively regulates phagocytosis in macrophages are unclear. We addressed the issue using bone marrow-derived macrophages from FcgammaR- or SHIP-deficient mice. Phagocytic activities of macrophages from FcgammaRII(b)(-/-) and SHIP(-/-) mice were enhanced to a similar extent, relative to those from wild type. However, calcium influx was only marginally affected in FcgammaRII(b)(-/-), but greatly enhanced in SHIP(-/-) macrophages. Furthermore, SHIP was phosphorylated on tyrosine residues upon FcgammaR aggregation even in macrophages from FcgammaRII(b)(-/-) mice or upon clustering of a chimeric receptor containing CD8 and the immunoreceptor tyrosine-based activation motif (ITAM)-bearing gamma-chain or human-restricted FcgammaRIIa. These findings indicate that, unlike B cells, SHIP is efficiently phosphorylated in the absence of an immunoreceptor tyrosine-based inhibition motif (ITIM)-bearing receptor. We further demonstrate that SHIP directly bound to phosphorylated peptides derived from FcgammaRIIa with a high affinity, comparable to that of FcgammaRII(b). Lastly, FcgammaRIIa-mediated phagocytosis was significantly enhanced in THP-1 cells overexpressing dominant-negative form of SHIP in the absence of FcgammaRII(b). These results indicate that SHIP negatively regulates FcgammaR-mediated phagocytosis through all ITAM-containing IgG receptors using a molecular mechanism distinct from that in B cells.
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MESH Headings
- Amino Acid Motifs
- Animals
- Antigens, CD/chemistry
- Antigens, CD/metabolism
- Bone Marrow Cells/cytology
- CD8 Antigens/genetics
- CD8 Antigens/physiology
- Calcium Signaling
- GPI-Linked Proteins
- Humans
- Macrophages/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Phagocytosis/physiology
- Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases
- Phosphoric Monoester Hydrolases/chemistry
- Phosphoric Monoester Hydrolases/deficiency
- Phosphoric Monoester Hydrolases/genetics
- Phosphoric Monoester Hydrolases/physiology
- Phosphorylation
- Phosphotyrosine/physiology
- Protein Processing, Post-Translational
- Receptors, IgG/chemistry
- Receptors, IgG/deficiency
- Receptors, IgG/metabolism
- Recombinant Fusion Proteins/metabolism
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Affiliation(s)
- Koji Nakamura
- Program in Immunobiology and Cancer, The Oklahoma Medical Research Foundation, 825 NE 13th Street, Oklahoma City, OK 73104, USA
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31
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Calverley DC, Brass E, Hacker MR, Tsao-Wei DD, Espina BM, Pullarkat VA, Hodis HN, Groshen S. Potential role of platelet FcgammaRIIA in collagen-mediated platelet activation associated with atherothrombosis. Atherosclerosis 2002; 164:261-7. [PMID: 12204796 DOI: 10.1016/s0021-9150(02)00179-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Collagen-mediated platelet activation contributes significantly to coronary and cerebrovascular thrombus formation associated with atherosclerotic plaque destabilization. Recent clinical and laboratory observations support a potential role for the platelet Fc receptor (FcgammaRIIA) in this process. The purpose of this study was to elucidate any association between platelet Fc receptor (FcR) expression levels and both atherosclerosis risk factors (ARFs) along with collagen-dependent platelet activation. Age and gender-independent variation has been described in the expression of this receptor that is stable over time. Platelet Fc surface expression was compared between patients experiencing an acute coronary or cerebrovascular event, healthy patients with two or more ARFs, and healthy patients with fewer than two ARFs. Platelet FcR expression was significantly and stably (6-52 weeks, mean 20 weeks) increased in 101 patients with acute myocardial infarction, unstable angina, or ischemic stroke syndrome (P<0.001) and 38 healthy patients with two or more ARFs (P=0.027) compared with 109 healthy patients with fewer than two ARFs. Patients with diabetes mellitus from all groups had significantly increased platelet FcR expression over those without diabetes (P<0.0001). Platelet aggregation studies suggested a correlation between number of ARFs per patient, platelet Fc expression levels, and relative sensitivity to collagen stimulation. Platelet FcR surface expression is increased in patients with an acute coronary or cerebrovascular event, non-acutely ill patients with two or more ARFs, and in patients with diabetes mellitus. Increased platelet FcR expression may therefore contribute towards risk for atherothrombotic events.
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Affiliation(s)
- David C Calverley
- Department of Medicine and the Mountain States Regional Hemophilia and Thrombosis Center, University of Colorado Health Sciences Center, 4200 East Ninth Avenue, Box B171, Denver, CO 80262, USA.
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32
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Abstract
Fcγ receptor–mediated phagocytosis is a complex process involving the activation of protein tyrosine kinases, events that are potentially down-regulated by protein tyrosine phosphatases. We used the J774A.1 macrophage cell line to examine the roles played by the protein tyrosine phosphatase SHP-1 in the negative regulation of Fcγ receptor–mediated phagocytosis. Stimulation with sensitized sheep red blood cells (sRBCs) induced tyrosine phosphorylation of CBL and association of CBL with CRKL. These events were completely or partially abrogated by PP1 or the heterologous expression of dominant-negative SYK, respectively. Heterologous expression of wild-type but not catalytically inactive SHP-1 also completely abrogated the phagocytosis of IgG-sensitized sRBCs. Most notably, overexpressed SHP-1 associates with CBL and this association led to CBL dephosphorylation, loss of the CBL-CRKL interaction, and the suppression of Rac activation. These data represent the first direct evidence that SHP-1 is involved in the regulation of Fcγ receptor–mediated phagocytosis and suggest that activating signals mediated by SRC family kinases SYK, CBL, phosphatidyl inositol-3 (PI-3) kinase, and Rac are directly opposed by inhibitory signals through SHP-1.
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33
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Kogut M, Lowry VK, Farnell M. Selective pharmacological inhibitors reveal the role of Syk tyrosine kinase, phospholipase C, phosphatidylinositol-3'-kinase, and p38 mitogen-activated protein kinase in Fc receptor-mediated signaling of chicken heterophil degranulation. Int Immunopharmacol 2002; 2:963-73. [PMID: 12188037 DOI: 10.1016/s1567-5769(02)00050-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Fc receptors of avian heterophils play a primary role in the elimination of bacterial pathogens in poultry. The cross-linking of Fc receptors with IgG-bacteria complexes results in the secretion of toxic oxygen metabolites and anti-bacterial granules. We have been investigating the upstream signaling events that precede degranulation following crosslinkage of Fc receptors on heterophils. Previously when using the non-selective pharmacological inhibitors genistein, chelerythrine, verapamil, and pertussis toxin, we found no significant inhibitory effects on Fc-mediated heterophil degranulation. In the present studies, we used more selective pharmacological inhibitors to investigate the roles of protein tyrosine kinases, phospholipase C (PLC), phosphatidylinositol 3'-kinase, and the family of mitogen-activated protein kinases (MAPK) on Fc-mediated heterophil degranulation. Inhibitors of the receptor-linked tyrosine kinases (the tryphostins AG 1478 and AG 1296) had no attenuating effects on the Fc receptor-mediated degranulation of chicken heterophils. Likewise, PP2, a selective inhibitor of the Src family of protein tyrosine kinases, had no inhibitory effects on degranulation. However, piceatannol, a selective inhibitor of Syk tyrosine kinase, significantly attenuated the effect of Fc receptor-mediated degranulation. Additionally, Fc-mediated degranulation was significantly attenuated by SB 203580, an inhibitor of p38 MAPK, but not by PD98059, an inhibitor of the extracellular signal-regulated kinase (ERK). An inhibitor of phospholipase C, U73122 and LY294002, an inhibitor of phosphoinositol-3 kinase significantly decreased heterophil degranulation. These results suggest that the Fc receptors on chicken heterophils, like their counterparts on mammalian neutrophils, have no intrinsic tyrosine kinase activity, but probably mediate downstream events through activation of tyrosine-based activation motifs (ITAM). Activation of the Syk tyrosine kinase stimulates downstream phosphorylation of p38 MAPK, phospholipase C, and phosphatidylinositol-3 kinase as signaling pathways that regulate Fc-receptor-mediated degranulation of chicken heterophils. Engaging Fc receptors on chicken heterophils activates a Syk-->PLC-->PI3-K-->p38 MAPK signal transduction pathway that induces degranulation.
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Affiliation(s)
- Michael Kogut
- USDA-ARS, Southern Plains Agricultural Research Center, College Station, TX 77845, USA.
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34
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Albrecht B, D'Souza CD, Ding W, Tridandapani S, Coggeshall KM, Lairmore MD. Activation of nuclear factor of activated T cells by human T-lymphotropic virus type 1 accessory protein p12(I). J Virol 2002; 76:3493-501. [PMID: 11884573 PMCID: PMC136046 DOI: 10.1128/jvi.76.7.3493-3501.2002] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human T-lymphotropic virus type 1 (HTLV-1) is the agent of an aggressive malignancy of CD4(+) T lymphocytes, called adult T-cell lymphoma/leukemia, and is associated with numerous immune-mediated diseases. To establish infection, HTLV-1 must activate targeted T cells during early stages of infection. We recently demonstrated that the HTLV-1 accessory protein p12(I) is critical for persistent infection in vivo and for viral infectivity in quiescent primary lymphocytes, suggesting a role for p12(I) in lymphocyte activation. To test whether p12(I) modulates signaling pathways required for T-lymphocyte activation, we examined AP-1-, NF-kappaB-, and nuclear factor of activated T cells (NFAT)-driven reporter gene activity in p12(I)-expressing Jurkat T cells compared to vector-transfected control cells. HTLV-1 p12(I) specifically induced NFAT-mediated transcription approximately 20-fold in synergy with the Ras/mitogen-activated protein kinase pathway, but did not influence AP-1- or NF-kappaB-dependent gene expression. Inhibition of calcium-dependent signals by cyclosporin A, BAPTA-AM [glycine, N,N'-1,2-ethanediylbis(oxy-2,1-phenylene)-bis-N-2-(acetyloxy)methoxy-2-oxoethyl]-[bis(acetyloxy)methyl ester], and a dominant negative mutant of NFAT2 abolished the p12(I)-mediated activation of NFAT-dependent transcription. In contrast, inhibition of phospholipase C-gamma and LAT (linker for activation of T cells) did not affect p12(I)-induced NFAT activity. Importantly, p12(I) functionally substituted for thapsigargin, which selectively depletes intracellular calcium stores. Our data are the first to demonstrate a role for HTLV-1 p12(I) in calcium-dependent activation of NFAT-mediated transcription in lymphoid cells. We propose a novel mechanism by which HTLV-1, a virus associated with lymphoproliferative disease, dysregulates common T-cell activation pathways critical for the virus to establish persistent infection.
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Affiliation(s)
- Björn Albrecht
- Center for Retrovirus Research and Department of Veterinary Biosciences, College of Medicine and Public Health, The Ohio State University, Columbus, Ohio 43210, USA
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35
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Hiller G, Sundler R. Regulation of phospholipase C-gamma 2 via phosphatidylinositol 3-kinase in macrophages. Cell Signal 2002; 14:169-73. [PMID: 11781142 DOI: 10.1016/s0898-6568(01)00252-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Phospholipase C-gamma (PLC-gamma) isoforms are thought to be activated by both tyrosine phosphorylation and phosphatidylinositol 3,4,5 trisphosphate (PtdIns 3,4,5 P(3)), the product of phosphatidylinositol 3-kinase (PtdIns 3-kinase). In this study, we show that stimulation of mouse macrophages with either zymosan beads or bacteria (Prevotella intermedia) induced tyrosine phosphorylation of PLC-gamma 2. Zymosan stimulation also induced translocation to membrane and cytoskeleton fractions, which was inhibited by the PtdIns 3-kinase inhibitors wortmannin and LY 294002. However, the tyrosine phosphorylation of PLC-gamma 2 induced by zymosan was not affected by the inhibitors wortmannin and LY 294002. In contrast to zymosan and bacteria, PLC-gamma 2 was not phosphorylated by stimulation with lipopolysaccharide (LPS), phorbol ester or calcium ionophore. Moreover, the PLC-gamma 1 isoform was not detected in mouse macrophages. These data indicate that PtdIns 3-kinase is critical for the translocation but not for the tyrosine phosphorylation of PLC-gamma 2 in mouse macrophages and that the latter may be insufficient for enzyme activation.
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Affiliation(s)
- Gösta Hiller
- Department of Cell and Molecular Biology, B11, Biomedical Centre, Lund University, SE-221 84 Lund, Sweden
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36
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Chi M, Tridandapani S, Zhong W, Coggeshall KM, Mortensen RF. C-reactive protein induces signaling through Fc gamma RIIa on HL-60 granulocytes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:1413-8. [PMID: 11801683 DOI: 10.4049/jimmunol.168.3.1413] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Human C-reactive protein (CRP) at acute phase levels of 10-200 microg/ml triggered the phosphorylation of FcgammaRIIa, Syk kinase, and phospholipase Cgamma2 in granulocytic HL-60 cells. CRP also stimulated translocation to the membrane of both phospholipase Cgamma2 and phosphatidylinositol-3-kinase. The signaling response triggered by CRP was a rapid, early event with kinetics similar to the response elicited by human IgG. Both soluble-aggregated CRP and monomeric CRP cross-linked FcgammaRII to generate a signal of the same intensity. The results are consistent with signaling through the intrinsic immunoreceptor tyrosine-based activation motif of the cytoplasmic domain of FcgammaRIIa, the major CRP-receptor on monocytes and neutrophils that is responsible for CRP-mediated phagocytosis. The signaling events driven by CRP have the potential to regulate infiltrating neutrophil activities.
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Affiliation(s)
- Maoyen Chi
- Department of Microbiology, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
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37
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Kim JS, Peng X, De PK, Geahlen RL, Durden DL. PTEN controls immunoreceptor (immunoreceptor tyrosine-based activation motif) signaling and the activation of Rac. Blood 2002; 99:694-7. [PMID: 11781256 DOI: 10.1182/blood.v99.2.694] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fcgamma receptor-mediated phagocytosis is a model for the study of immunoreceptor (immunoreceptor tyrosine-based activation motif [ITAM]) signaling and involves the activation of protein tyrosine kinases, protein tyrosine phosphatases, and downstream effectors including phosphatidylinositol-3 (PI-3) kinase. Relatively little is known of the role of lipid phosphatases in the control of ITAM signaling and inflammation. A heterologous COS7 cell system was used to examine the roles played by PI-3 kinase and the dual-specificity phosphatase, phosphatase and tensin homolog deleted on chromosome 10 (PTEN), in the signal transduction pathway leading to Fcgamma receptor IIA-mediated phagocytosis and the activation of Rac. The expression of wildtype PTEN completely abrogated the phagocytosis of immunoglobulin-G-sensitized sheep red blood cells, as compared with the catalytically inactive mutant of PTEN, which had no effect. This is the first direct evidence that PTEN, an inositol 3' phosphatase, regulates Fcgamma receptor-mediated phagocytosis, an ITAM-based signaling event. The data suggest that PTEN exerts control over phagocytosis potentially by controlling the downstream conversion of guanosine diphosphate-Rac to guanosine triphosphate-Rac following ITAM stimulation.
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Affiliation(s)
- Jong Suk Kim
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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38
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García‐García E, Sánchez‐Mejorada G, Rosales C. Phosphatidylinositol 3‐kinase and ERK are required for NF‐κB activation but not for phagocytosis. J Leukoc Biol 2001. [DOI: 10.1189/jlb.70.4.649] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Erick García‐García
- Immunology Department, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City
| | - Gabriela Sánchez‐Mejorada
- Immunology Department, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City
| | - Carlos Rosales
- Immunology Department, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City
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39
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Antonieta Cote-Vélez MJ, Ortega E, Ortega A. Involvement of pp125FAK and p60SRC in the signaling through Fc gamma RII-Fc gamma RIII in murine macrophages. Immunol Lett 2001; 78:189-94. [PMID: 11578694 DOI: 10.1016/s0165-2478(01)00251-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cross-linking the FcgammaRs can activate a wide variety of biological responses in macrophages. Receptor stimulation induces activation of protein tyrosine kinase cascades that result in phagocytosis, a process known to involve cytoskeletal rearrangements. Therefore, an involvement of non-receptor tyrosine kinases such as pp125FAK, in FcgammaR signaling is likely. Using the murine macrophage cell line J774, we demonstrate that FcgammaRII-RIII cross-linking induces a time- and dose-dependent increase in tyrosine phosphorylation of the focal adhesion kinase pp125FAK that correlates with an increase in its catalytic activity. Interestingly enough, pp125FAK activation results in its association both to the FcgammaRII-III and to p60Src. The results presented here define a novel-signaling pathway likely to be important in low affinity FcgammaRII-III mediated phagocytosis.
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Affiliation(s)
- M J Antonieta Cote-Vélez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, D.F. 07000, Mexico, Mexico
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40
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Cooney DS, Phee H, Jacob A, Coggeshall KM. Signal transduction by human-restricted Fc gamma RIIa involves three distinct cytoplasmic kinase families leading to phagocytosis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:844-54. [PMID: 11441091 DOI: 10.4049/jimmunol.167.2.844] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Recent experiments indicate an important role for Src family and Syk protein tyrosine kinases and phosphatidylinositol 3-kinase in the signal transduction process initiated by mouse receptors for IgG and leading to phagocytosis. Considerably less is known regarding signal transduction by the human-restricted IgG receptor, FcgammaRIIa. Furthermore, the relationship among the Src family, Syk, and phosphatidylinositol 3-kinase in phagocytosis is not understood. Here, we show that FcgammaRIIa is phosphorylated by an Src family member, which results in recruitment and concomitant activation of the distal enzymes Syk and phosphatidylinositol 3-kinase. Using a FcgammaRI-p85 receptor chimera cotransfected with kinase-inactive mutants of Syk or application of a pharmacological inhibitor of Syk, we show that Syk acts in parallel with phosphatidylinositol 3-kinase. Our results indicate that FcgammaRIIa-initiated monocyte or neutrophil phagocytosis proceeds from the clustered IgG receptor to Src to phosphatidylinositol 3-kinase and Syk.
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Affiliation(s)
- D S Cooney
- Immunobiology and Cancer Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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41
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Abstract
The process of engulfing a foreign particle - phagocytosis - is of fundamental importance for a wide diversity of organisms. From simple unicellular organisms that use phagocytosis to obtain their next meal, to complex metazoans in which phagocytic cells represent an essential branch of the immune system, evolution has armed cells with a fantastic repertoire of molecules that serve to bring about this complex event. Regardless of the organism or specific molecules concerned, however, all phagocytic processes are driven by a finely controlled rearrangement of the actin cytoskeleton. A variety of signals can converge to locally reorganise the actin cytoskeleton at a phagosome, and there are significant similarities and differences between different organisms and between different engulfment processes within the same organism. Recent advances have demonstrated the complexity of phagocytic signalling, such as the involvement of phosphoinostide lipids and multicomponent signalling complexes in transducing signals from phagocytic receptors to the cytoskeleton. Similarly, a wide diversity of ‘effector molecules’ are now implicated in actin-remodelling downstream of these receptors.
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Affiliation(s)
- R C May
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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42
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FcγRIIA requires a Gi-dependent pathway for an efficient stimulation of phosphoinositide 3-kinase, calcium mobilization, and platelet aggregation. Blood 2000. [DOI: 10.1182/blood.v96.10.3439] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractFcγRIIA, the only Fcγ receptor present in platelets, is involved in heparin-associated thrombocytopenia (HIT). Recently, adenosine diphosphate (ADP) has been shown to play a major role in platelet activation and aggregation induced by FcγRIIA cross-linking or by sera from HIT patients. Herein, we investigated the mechanism of action of ADP as a cofactor in FcγRIIA-dependent platelet activation, which is classically known to involve tyrosine kinases. We first got pharmacologic evidence that the ADP receptor coupled to Gi was required for HIT sera or FcγRIIA clustering-induced platelet secretion and aggregation. Interestingly, the signaling from this ADP receptor could be replaced by triggering another Gi-coupled receptor, the α2A-adrenergic receptor. ADP scavengers did not significantly affect the tyrosine phosphorylation cascade initiated by FcγRIIA cross-linking. Conversely, the Gi-dependent signaling pathway, initiated either by ADP or epinephrine, was required for FcγRIIA-mediated phospholipase C activation and calcium mobilization. Indeed, concomitant signaling from Gi and FcγRIIA itself was necessary for an efficient synthesis of phosphatidylinositol 3,4,5-trisphosphate, a second messenger playing a critical role in the process of phospholipase Cγ2 activation. Altogether, our data demonstrate that converging signaling pathways from Gi and tyrosine kinases are required for platelet secretion and aggregation induced by FcγRIIA.
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FcγRIIA requires a Gi-dependent pathway for an efficient stimulation of phosphoinositide 3-kinase, calcium mobilization, and platelet aggregation. Blood 2000. [DOI: 10.1182/blood.v96.10.3439.h8003439_3439_3446] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
FcγRIIA, the only Fcγ receptor present in platelets, is involved in heparin-associated thrombocytopenia (HIT). Recently, adenosine diphosphate (ADP) has been shown to play a major role in platelet activation and aggregation induced by FcγRIIA cross-linking or by sera from HIT patients. Herein, we investigated the mechanism of action of ADP as a cofactor in FcγRIIA-dependent platelet activation, which is classically known to involve tyrosine kinases. We first got pharmacologic evidence that the ADP receptor coupled to Gi was required for HIT sera or FcγRIIA clustering-induced platelet secretion and aggregation. Interestingly, the signaling from this ADP receptor could be replaced by triggering another Gi-coupled receptor, the α2A-adrenergic receptor. ADP scavengers did not significantly affect the tyrosine phosphorylation cascade initiated by FcγRIIA cross-linking. Conversely, the Gi-dependent signaling pathway, initiated either by ADP or epinephrine, was required for FcγRIIA-mediated phospholipase C activation and calcium mobilization. Indeed, concomitant signaling from Gi and FcγRIIA itself was necessary for an efficient synthesis of phosphatidylinositol 3,4,5-trisphosphate, a second messenger playing a critical role in the process of phospholipase Cγ2 activation. Altogether, our data demonstrate that converging signaling pathways from Gi and tyrosine kinases are required for platelet secretion and aggregation induced by FcγRIIA.
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Shen L, Lang ML, Wade WF. The ins and outs of getting in: structures and signals that enhance BCR or Fc receptor-mediated antigen presentation. IMMUNOPHARMACOLOGY 2000; 49:227-40. [PMID: 10996020 DOI: 10.1016/s0162-3109(00)00255-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Antigen-presenting cells internalize antigen by fluid-phase pinocytosis or by endocytosis via surface receptors such as the B cell receptor (BCR) and Fc receptors for IgG, IgA and IgE (FcR). While both modes of internalization lead to antigen presentation it is recognized that receptor-mediated endocytosis greatly enhances the efficiency of processing and antigen presentation. Receptors facilitate the entry of antigen into the endocytic pathway by interaction of their internalization motifs with the endocytic machinery. These motifs include tyrosine-based, dileucine and casein kinase-like motifs. However these structures appear insufficient to support processing of cryptic epitopes, leading to a limited immune response. Cryptic epitope processing appears dependent on receptor signaling which is mediated by immunoreceptor tyrosine activation motifs (ITAMs). The signaling cascade which follows receptor crosslinking promotes reorganization and acidification of the late endocytic compartment or MIIC. Signaling events downstream of Syk, in particular calcium flux and protein kinase C activation, are necessary for MIIC induction. PI(3) kinase is also involved at multiple steps in antigen presentation, including production of PIP3 and transport of cathepsins. PIP3 is crucial both as a binding substrate for proteins implicated in vesicle transport and for the recruitment of signaling molecules to the plasma membrane. Among PIP3 activated molecules, protein kinase B (PKB) has been linked to endocytic function. We observe association of activated PKB with the MIIC after signaling through antigen presentation-competent receptors, but not mutant, presentation-defective receptors.
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Affiliation(s)
- L Shen
- Department of Microbiology, Dartmouth Medical School, Lebanon, NH 03756, USA
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Tridandapani S, Lyden TW, Smith JL, Carter JE, Coggeshall KM, Anderson CL. The adapter protein LAT enhances fcgamma receptor-mediated signal transduction in myeloid cells. J Biol Chem 2000; 275:20480-7. [PMID: 10781611 DOI: 10.1074/jbc.m909462199] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
FcgammaR clustering in monocytes initiates a cascade of signaling events that culminate in biological responses such as phagocytosis, production of inflammatory cytokines, and generation of reactive oxygen species. We have identified and determined the function of the adapter protein linker of activation of T cell (LAT) in FcgammaR-mediated signaling and function. Clustering of FcgammaRs on the human monocytic cell line, THP-1, induces phosphorylation of a major 36-kDa protein which immunoreacts with anti-LAT antisera. Our data indicate that although both the 36-kDa and 38-kDa isoforms of LAT are expressed in THP-1 and U937 human monocytic cells, FcgammaR clustering induces phosphorylation of the 36-kDa isoform only. Co-immunoprecipitation experiments revealed a constitutive association of p36 LAT with both FcgammaRI and FcgammaRIIa immunoprecipitates, and an activation-induced association of LAT with PLCgamma1, Grb2, and the p85 subunit of phosphatidylinositol 3-kinase. Transient transfection experiments in COS-7 cells indicated that overexpression of a wild type but not a dominant-negative LAT, that is incapable of binding to p85, enhances phagocytosis by FcgammaRI. Furthermore, bone marrow-derived macrophages from LAT-deficient mice displayed reduced phagocytic efficiency in comparison to the macrophages from wild-type mice. Thus, we conclude that p36 LAT serves to enhance FcgammaR-induced signal transduction in myeloid cells.
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Affiliation(s)
- S Tridandapani
- Department of Internal Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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46
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Strzelecka A, Pyrzyńska B, Kwiatkowska K, Sobota A. Syk kinase, tyrosine-phosphorylated proteins and actin filaments accumulate at forming phagosomes during Fcgamma receptor-mediated phagocytosis. CELL MOTILITY AND THE CYTOSKELETON 2000; 38:287-96. [PMID: 9384219 DOI: 10.1002/(sici)1097-0169(1997)38:3<287::aid-cm7>3.0.co;2-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Phagocytosis mediated by Fcgamma receptors (FcgammaRs) is thought to be regulated by a cascade of tyrosine phosphorylation events that finally leads to the rearrangement of submembranous actin-based cytoskeleton and internalization of particles. Suggestions concerning the functional relationship between protein tyrosine kinases, their substrates, and actin filament reorganization prompted us to determine cellular distribution of these elements during uptake of IgG-coated particles in murine thio-macrophages. We found that the onset of uptake of the particles was accompanied by tyrosine phosphorylation of several proteins, among which 90, 50, 40, 30, and 25 kDa polypeptides were distinguished. In most of the proteins the tyrosine hyperphosphorylation persisted up to 3 min of the uptake; however, kinetics of the phosphorylation of individual proteins varied. Immunofluorescence data showed that the phosphotyrosine-bearing proteins were localized in regions of the particle uptake, being concentrated at phagocytic cups and nascent phagosomes. The local enrichment in tyrosine phosphorylated proteins was correlated with accumulation of actin filaments at these early stages of phagosome formation. During phagosome maturation, both tyrosine phosphorylated proteins and microfilaments disappeared from the periphagosomal regions. Syk, one of the tyrosine kinases, was translocated to the regions where FcgammaR-mediated phagocytosis had started. On the contrary, no enrichment in phosphatidylinositol 3-kinase was detected in these places.
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Affiliation(s)
- A Strzelecka
- Nencki Institute of Experimental Biology, Department of Cell Biology, Warsaw, Poland
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Pain S, Falet H, Saci A, Bachelot-Loza C, Rendu F. Tyrosine phosphorylation and association of FcgammaRII and p72(Syk) are not limited to the FcgammaRII signalling pathway. Cell Signal 2000; 12:165-71. [PMID: 10704823 DOI: 10.1016/s0898-6568(99)00079-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The tyrosine kinase p72(Syk) plays a critical role in platelet signal transduction. It associates with the platelet receptor for the Fc domain of IgGs, FcgammaRII, following stimulation by FcgammaRII cross-linking. Here, we show that p72(Syk) and FcgammaRII tyrosine phosphorylation and association occured following platelet stimulation by: (1) two monoclonal antibodies, which form a bridge between a target antigen and FcgammaRII, and (2) the G-protein-coupled receptor agonist thrombin. The kinetics of the p72(Syk)/FcgammaRII association depended on the signalling pathway (i.e., the antigen targeted or the thrombin receptor). We established a direct relationship between the level of FcgammaRII phosphorylation and the detection of its association with p72(Syk). Inhibition of p72(Syk) by piceatannol resulted in partial or total inhibition of FcgammaRII phosphorylation, after immunological activation or addition of thrombin, respectively, suggesting that p72(Syk) participates in FcgammaRII phosphorylation. The results provide evidence that p72(Syk)/FcgammaRII association is not restricted to immunological activation.
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Affiliation(s)
- S Pain
- U428 INSERM, UFR des Sciences pharmaceutiques et Biologiques, 4 avenue de l'Observatoire, 75270, Paris, France
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48
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Lin TJ, Hirji N, Stenton GR, Gilchrist M, Grill BJ, Schreiber AD, Befus AD. Activation of macrophage CD8: pharmacological studies of TNF and IL-1 beta production. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:1783-92. [PMID: 10657625 DOI: 10.4049/jimmunol.164.4.1783] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Previously, we demonstrated that rat macrophages express CD8 and that Ab to CD8 stimulates NO production. We confirm that CD8 is expressed by rat macrophages and extend understanding of its functional significance. Activation of CD8 alpha (OX8 Ab) on alveolar macrophages stimulated mRNA expression for TNF and IL-1 beta and promoted TNF and IL-1 beta secretion. Similarly, OX8 Ab (CD8 alpha) stimulated NR8383 cells to secrete TNF, IL-1 beta, and NO. Activation of CD8 beta (Ab 341) on alveolar macrophages increased mRNA expression for TNF and IL-1 beta and stimulated secretion of TNF, but not IL-1 beta. Interestingly, anti-CD8 Abs did not stimulate IFN-gamma or PGE2 production, or phagocytosis by macrophages. OX8 (CD8 alpha)-induced TNF and IL-1 beta production by macrophages was blocked by inhibitors of protein tyrosine kinase(s), PP1, and genistein, but not by phosphatidylinositol-3 kinase inhibitor, wortmannin. Moreover, OX8 stimulated protein tyrosine kinase activity in NR8383 cells. Further analysis of kinase dependence using antisense to Syk kinase demonstrated that TNF, but not IL-1 beta, stimulation by CD8 alpha is Syk dependent. By contrast, protein kinase C inhibitor Ro 31-8220 had no effect on OX8-induced TNF production, whereas OX8-induced IL-1 beta production was blocked by Ro 31-8220. Thus, there are distinct signaling mechanisms involved in CD8 alpha (OX8)-induced TNF and IL-1 beta production. In summary, macrophages express CD8 molecules that, when activated, stimulate TNF and IL-1 beta expression, probably through mechanisms that include activation of Src and Syk kinases and protein kinase C. These findings identify a previously unknown pathway of macrophage activation likely to be involved in host defense and inflammation.
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Affiliation(s)
- T J Lin
- Department of Microbiology, Dalhousie University, Halifax, Nova Scotia, Canada, USA
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49
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Chuang FY, Sassaroli M, Unkeless JC. Convergence of Fc gamma receptor IIA and Fc gamma receptor IIIB signaling pathways in human neutrophils. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:350-60. [PMID: 10605030 DOI: 10.4049/jimmunol.164.1.350] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Human neutrophils (PMNs) express two receptors for the Fc domain of IgG: the transmembrane FcgammaRIIA, whose cytosolic sequence contains an immunoreceptor tyrosine-based activation motif, and the GPI-anchored FcgammaRIIIB. Cross-linking of FcgammaRIIIB induces cell activation, but the mechanism is still uncertain. We have used mAbs to cross-link selectively each of the two receptors and to assess their signaling phenotypes and functional relation. Cross-linking of FcgammaRIIIB induces intracellular Ca2+ release and receptor capping. The Ca2+ response is blocked by wortmannin and by N,N-dimethylsphingosine, inhibitors of phosphatidylinositol 3-kinase and sphingosine kinase, respectively. Identical dose-response curves are obtained for the Ca2+ release stimulated by cross-linking FcgammaRIIA, implicating these two enzymes in a common signaling pathway. Wortmannin also inhibits capping of both receptors, but not receptor endocytosis. Fluorescence microscopy in double-labeled PMNs demonstrates that FcgammaRIIA colocalizes with cross-linked FcgammaRIIIB. The signaling phenotypes of the two receptors diverge only under frustrated phagocytosis conditions, where FcgammaRIIIB bound to substrate-immobilized Ab does not elicit cell spreading. We propose that FcgammaRIIIB signaling is conducted by molecules of FcgammaRIIA that are recruited to protein/lipid domains induced by clustered FcgammaRIIIB and, thus, are brought into juxtaposition for immunoreceptor tyrosine-based activation motif phosphorylation and activation of PMNs.
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Affiliation(s)
- F Y Chuang
- Department of Biochemistry, Mount Sinai School of Medicine, New York 10029, USA
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50
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Raeder EMB, Mansfield PJ, Hinkovska-Galcheva V, Shayman JA, Boxer LA. Syk Activation Initiates Downstream Signaling Events During Human Polymorphonuclear Leukocyte Phagocytosis. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.12.6785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Abstract
We investigated the requirement for Syk activation to initiate downstream signaling events during polymorphonuclear leukocyte (PMN) phagocytosis of Ab-coated erythrocytes (EIgG). When PMN were challenged with EIgG, Syk phosphorylation increased in a time-dependent manner, paralleling the response of PMN phagocytosis. Pretreatment of PMN with piceatannol, a Syk-selective inhibitor, blocked EIgG phagocytosis and Syk phosphorylation. We found that piceatannol inhibited protein kinase Cδ (PKCδ) and Raf-1 translocation from cytosol to plasma membrane by >90%. Extracellular signal-regulated protein kinase-1 and -2 (ERK1 and ERK2) phosphorylation was similarly blocked. We also investigated phosphatidylinositide 3-kinase (PI 3-kinase) activity and Syk phosphorylation using piceatannol, wortmannin, and LY294002, inhibitors of PI 3-kinase. The phosphorylation of Syk preceded the activation of PI 3-kinase. Both wortmannin and piceatannol inhibited PI 3-kinase, but only piceatannol inhibited Syk. In contrast to piceatannol, wortmannin did not inhibit PKCδ and Raf-1 translocation. To elucidate signaling downstream of Syk activation, we assessed whether the cell-permeable diacylglycerol analogue didecanoylglycerol could normalize PMN phagocytosis, PKCδ and Raf-1 translocation, and ERK1 and ERK2 phosphorylation inhibited by piceatannol. The addition of didecanoylglycerol to the Syk-inhibited phagocytosing PMN normalized all three without a concomitant effect on PI 3-kinase activity and Syk phosphorylation. We conclude that Syk activation following Fcγ receptor engagement initiates downstream signaling events leading to mitogen-activated protein kinase activation independent of PI 3-kinase activation.
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Affiliation(s)
| | | | | | - James A. Shayman
- †Department of Internal Medicine, Division of Nephrology, University of Michigan, Ann Arbor, MI 48109
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