51
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Fournier EM, Sibéril S, Costes A, Varin A, Fridman WH, Teillaud JL, Sautès-Fridman C. Activation of Human Peripheral IgM+ B Cells Is Transiently Inhibited by BCR-Independent Aggregation of FcγRIIB. THE JOURNAL OF IMMUNOLOGY 2008; 181:5350-9. [DOI: 10.4049/jimmunol.181.8.5350] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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52
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Abstract
These studies investigate how interactions between the BCR and FcgammaRIIB affect B lymphocyte stimulator (BLyS) recep-tor expression and signaling. Previous studies showed that BCR ligation up-regulates BLyS binding capacity in mature B cells, reflecting increased BLyS receptor levels. Here we show that FcgammaRIIB coaggregation dampens BCR-induced BLyS receptor up-regulation. This cross-regulation requires BCR and FcgammaRIIB coligation, and optimal action relies on the Src-homology-2 (SH2)-containing inositol 5 phosphase-1 (SHIP1). Subsequent to FcgammaRIIB/BCR coaggregation, the survival promoting actions of BLyS are attenuated, reflecting reduced BLyS receptor signaling capacity in terms of Pim 2 maintenance, noncanonical NF-kappaB activation, and Bcl-xL levels. These findings link the negative regulatory functions of FcgammaRIIB with BLyS-mediated B-cell survival.
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53
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Kuperman DA, Schleimer RP. Interleukin-4, interleukin-13, signal transducer and activator of transcription factor 6, and allergic asthma. Curr Mol Med 2008; 8:384-92. [PMID: 18691065 DOI: 10.2174/156652408785161032] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Interleukin (IL)-4 and IL-13 share many biological activities. To some extent, this is because they both signal via a shared receptor, IL-4Ralpha. Ligation of IL-4Ralpha results in activation of Signal Transducer and Activator of Transcription factor 6 (STAT6) and Insulin Receptor Substrate (IRS) molecules. In T- and B-cells, IL-4Ralpha signaling contributes to cell-mediated and humoral aspects of allergic inflammation. It has recently become clear that IL-4 and IL-13 produced in inflamed tissues activate signaling in normally resident cells of the airway. The purpose of this review is to critically evaluate the contributions of IL-4- and IL-13-induced tissue responses, especially those mediated by STAT6, to some of the pathologic features of asthma including eosinophilic inflammation, airway hyperresponsiveness, subepithelial fibrosis and excessive mucus production. We also review the functions of some recently identified IL-4- and/or IL-13-induced mediators that provide some detail on molecular mechanisms and suggest an important contribution to host defense.
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Affiliation(s)
- Douglas A Kuperman
- Northwestern University Feinberg School of Medicine, Department of Medicine, Division of Allergy-Immunology, Chicago, Illinois 60611, USA.
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54
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Abstract
Receptors carrying immunoreceptor tyrosine-based inhibition motifs (ITIMs) in their cytoplasmic tail control a vast array of cellular responses, ranging from autoimmunity, allergy, phagocytosis of red blood cells, graft versus host disease, to even neuronal plasticity in the brain. The inhibitory function of many receptors has been deduced on the basis of cytoplasmic ITIM sequences. Tight regulation of natural killer (NK) cell cytotoxicity and cytokine production by inhibitory receptors specific for major histocompatibility complex class I molecules has served as a model system to study the negative signaling pathway triggered by an ITIM-containing receptor in the physiological context of NK-target cell interactions. Advances in our understanding of the molecular details of inhibitory signaling in NK cells have provided a conceptual framework to address how ITIM-mediated regulation controls cellular reactivity in diverse cell types.
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Affiliation(s)
- Eric O Long
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
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55
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Cady CT, Rice JS, Ott VL, Cambier JC. Regulation of hematopoietic cell function by inhibitory immunoglobulin G receptors and their inositol lipid phosphatase effectors. Immunol Rev 2008; 224:44-57. [PMID: 18759919 PMCID: PMC2968700 DOI: 10.1111/j.1600-065x.2008.00663.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Numerous autoimmune and inflammatory disorders stem from the dysregulation of hematopoietic cell activation. The activity of inositol lipid and protein tyrosine phosphatases, and the receptors that recruit them, is critical for prevention of these disorders. Balanced signaling by inhibitory and activating receptors is now recognized to be an important factor in tuning cell function and inflammatory potential. In this review, we provide an overview of current knowledge of membrane proximal events in signaling by inhibitory/regulatory receptors focusing on structural and functional characteristics of receptors and their effectors Src homology 2 (SH2) domain-containing tyrosine phosphatase 1 and SH2 domain-containing inositol 5-phosphatase-1. We review use of new strategies to identify novel regulatory receptors and effectors. Finally, we discuss complementary actions of paired inhibitory and activating receptors, using Fc gammaRIIA and Fc gammaRIIB regulation human basophil activation as a prototype.
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Affiliation(s)
- Carol T. Cady
- Department of Immunology, University of Colorado Denver School of Medicine, Denver, CO, USA
- National Jewish Medical and Research Center, Denver, CO, USA
| | - Jeffrey S. Rice
- Department of Immunology, University of Colorado Denver School of Medicine, Denver, CO, USA
- National Jewish Medical and Research Center, Denver, CO, USA
| | - Vanessa L. Ott
- Department of Immunology, University of Colorado Denver School of Medicine, Denver, CO, USA
- National Jewish Medical and Research Center, Denver, CO, USA
| | - John C. Cambier
- Department of Immunology, University of Colorado Denver School of Medicine, Denver, CO, USA
- National Jewish Medical and Research Center, Denver, CO, USA
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56
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O'Shea JJ, Johnston JA, Kehrl J, Koretzky G, Samelson LE. Key molecules involved in receptor-mediated lymphocyte activation. ACTA ACUST UNITED AC 2008; Chapter 11:Unit 11.9A. [PMID: 18432708 DOI: 10.1002/0471142735.im1109as44] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This unit, along with Unit 11.9B, provides a summary of our current knowledge about various signaling pathways critical to the function of immune cells. Here, our understanding of T cell receptor (TCR)- and B cell receptor (BCR)-mediated signaling is summarized. A schematic representation of immunologically relevant cytokine receptors and the Janus Family Kinases (JAKs) that is activated through these receptors is provided, along with details about molecules involved in interleukin 2 mediated signal transduction.
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Affiliation(s)
- J J O'Shea
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, Bethesda, Maryland, USA
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57
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Mediation of apoptosis by and antitumor activity of lumiliximab in chronic lymphocytic leukemia cells and CD23+ lymphoma cell lines. Blood 2008; 111:1594-602. [DOI: 10.1182/blood-2007-03-082024] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractLumiliximab is a chimeric macaque-human monoclonal antibody to CD23, a protein expressed on virtually all chronic lymphocytic leukemia (CLL) cells. We examined the ability of lumiliximab to mediate apoptosis, antibody-dependent cellular cytotoxicity, and complement-dependent cytotoxicity against primary CLL cells and CD23-expressing B-cell lines. Our data suggest that lumiliximab kills CLL cells and CD23-expressing B cells predominantly by apoptosis, which occurs through the intrinsic pathway. Lumiliximab-induced apoptosis was accompanied by the down-regulation of antiapoptotic proteins Bcl-2, Bcl-XL, and XIAP, activation of Bax, and release of cytochrome c from the mitochondria. We also found that the addition of lumiliximab to rituximab or fludarabine results in synergistic cytotoxicity of primary CLL cells and CD23-expressing B-cell lines. We investigated the in vivo activity of lumiliximab in a human disseminated CD23+ B-cell lymphoma SCID mouse model and found greater antitumor activity with it than with control antibody. We also found that paralysis-free survival was greater with lumiliximab plus rituximab or fludarabine than with any of those agents alone. These results suggest that lumiliximab may be an effective treatment alone or in combination with rituximab or chemotherapy agents in CLL or other CD23-overexpressing B-cell malignancies.
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58
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Abstract
Alterations in the cytosolic concentration of calcium ions (Ca2+) transmit information that is crucial for the development and function of B cells. Cytosolic Ca2+ concentration is determined by a balance of active transport and gradient-driven Ca2+ fluxes, both of which are subject to the influence of multiple receptors and environmental sensing pathways. Recent advances in genomics have allowed for the compilation of an increasingly comprehensive list of Ca2+ transporters and channels expressed by B cells. The increasing understanding of the function and regulation of these proteins has begun to shift the frontier of Ca2+ physiology in B cells from molecular analysis to determining how diverse inputs to cytosolic Ca2+ concentration are integrated in specific immunological contexts.
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Affiliation(s)
- Andrew M. Scharenberg
- Departments of Pediatrics and Immunology, University of Washington School of Medicine and, Children's Hospital and Regional Medical Center, Suite 300, 307 Westlake Ave, Seattle, WA 98109, USA
| | - Lisa A. Humphries
- Departments of Pediatrics and Immunology, University of Washington School of Medicine and, Children's Hospital and Regional Medical Center, Suite 300, 307 Westlake Ave, Seattle, WA 98109, USA
| | - David J. Rawlings
- Departments of Pediatrics and Immunology, University of Washington School of Medicine and, Children's Hospital and Regional Medical Center, Suite 300, 307 Westlake Ave, Seattle, WA 98109, USA
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59
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Grande SM, Bannish G, Fuentes-Panana EM, Katz E, Monroe JG. Tonic B-cell and viral ITAM signaling: context is everything. Immunol Rev 2007; 218:214-34. [PMID: 17624955 DOI: 10.1111/j.1600-065x.2007.00535.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The presence of an immunoreceptor tyrosine-based activation motif (ITAM) makes immunoreceptors different from other signaling receptors, like integrins, G-coupled protein receptors, chemokine receptors, and growth factor receptors. This unique motif has the canonical sequence D/Ex(0-2)YxxL/Ix(6-8)YxxL/I, where x represents any amino acid and is present at least once in all immunoreceptor complexes. Immunoreceptors can promote survival, activation, and differentiation by transducing signals through these highly conserved motifs. Traditionally, ITAM signaling is thought to occur in response to ligand-induced aggregation, although evidence indicates that ligand-independent tonic signaling also provides functionally relevant signals. The majority of proteins containing ITAMs are transmembrane proteins that exist as part of immunoreceptor complexes. However, oncogenic viruses also have ITAM-containing proteins. In this review, we discuss what is known about tonic signaling by both cellular and viral ITAM-containing proteins and speculate what we might learn from each context.
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Affiliation(s)
- Shannon M Grande
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
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60
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Liu Y, Kruhlak MJ, Hao JJ, Shaw S. Rapid T cell receptor-mediated SHP-1 S591 phosphorylation regulates SHP-1 cellular localization and phosphatase activity. J Leukoc Biol 2007; 82:742-51. [PMID: 17575265 PMCID: PMC2084461 DOI: 10.1189/jlb.1206736] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Since the tyrosine phosphatase SHP-1 plays a major role in regulating T cell signaling, we investigated regulation thereof by Ser/Thr phosphorylation. We found that T cell receptor (TCR) stimulation induced fast (
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Affiliation(s)
- Yin Liu
- Experimental Immunology Branch, Bldg. 10/4B05 National Cancer Institute, NIH Bethesda, MD 20892, USA
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61
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Sankarshanan M, Ma Z, Iype T, Lorenz U. Identification of a novel lipid raft-targeting motif in Src homology 2-containing phosphatase 1. THE JOURNAL OF IMMUNOLOGY 2007; 179:483-90. [PMID: 17579069 DOI: 10.4049/jimmunol.179.1.483] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The tyrosine phosphatase Src homology 2-containing phosphatase 1 (SHP-1) is a key negative regulator of TCR-mediated signaling. Previous studies have shown that in T cells a fraction of SHP-1 constitutively localizes to membrane microdomains, commonly referred to as lipid rafts. Although this localization of SHP-1 is required for its functional regulation of T cell activation events, how SHP-1 is targeted to the lipid rafts was unclear. In this study, we identify a novel, six-amino acid, lipid raft-targeting motif within the C terminus of SHP-1 based on several biochemical and functional observations. First, mutations of this motif in the context of full-length SHP-1 result in the loss of lipid raft localization of SHP-1. Second, this motif alone restores raft localization when fused to a mutant of SHP-1 (SHP-1 DeltaC) that fails to localize to rafts. Third, a peptide encompassing the 6-mer motif directly binds to phospholipids whereas a mutation of this motif abolishes lipid binding. Fourth, whereas full-length SHP-1 potently inhibits TCR-induced tyrosine phosphorylation of specific proteins, expression of a SHP-1-carrying mutation within the 6-mer motif does not. Additionally, although SHP-1 DeltaC was functionally inactive, the addition of the 6-mer motif restored its functionality in inhibiting TCR-induced tyrosine phosphorylation. Finally, this 6-mer mediated targeting of SHP-1 lipid rafts was essential for the function of this phosphatase in regulating IL-2 production downstream of TCR. Taken together, these data define a novel 6-mer motif within SHP-1 that is necessary and sufficient for lipid raft localization and for the function of SHP-1 as a negative regulator of TCR signaling.
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Affiliation(s)
- Mohan Sankarshanan
- Department of Microbiology, University of Virginia Health System, Charlottesville, VA 22908, USA
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62
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Abstract
Mast cells are effector cells of the innate immune system, but because they express Fc receptors (FcRs), they can be engaged in adaptive immunity by antibodies. Mast cell FcRs include immunoglobulin E (IgE) and IgG receptors and, among these, activating and inhibitory receptors. The engagement of mast cell IgG receptors by immune complexes may or may not trigger cell activation, depending on the type of mast cell. The coengagement of IgG and IgE receptors results in inhibition of mast cell activation. The Src homology-2 domain-containing inositol 5-phosphatase-1 is a major effector of negative regulation. Biological responses of mast cells depend on the balance between positive and negative signals that are generated in FcR complexes. The contribution of human mast cell IgG receptors in allergies remains to be clarified. Increasing evidence indicates that mast cells play critical roles in IgG-dependent tissue-specific autoimmune diseases. Convincing evidence was obtained in murine models of multiple sclerosis, rheumatoid arthritis, bullous pemphigoid, and glomerulonephritis. In these models, the intensity of lesions depended on the relative engagement of activating and inhibitory IgG receptors. In vitro models of mature tissue-specific murine mast cells are needed to investigate the roles of mast cells in these diseases. One such model unraveled unique differentiation/maturation-dependent biological responses of serosal-type mast cells.
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Affiliation(s)
- Odile Malbec
- Unité d'Allergologie Moléculaire et Cellulaire, Département d'Immunologie, Institut Pasteur, Paris, France
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63
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Abstract
Discovery of a large family of Fc receptor-like (FCRL) molecules, homologous to the well-known receptors for the Fc portion of immunoglobulin (FCR), has uncovered an impressive abundance of immunoglobulin superfamily (IgSF) genes in the human 1q21-23 chromosomal region and revealed significant diversity for these genes between humans and mice. The observation that FCRL representatives are members of an ancient multigene family that share a common ancestor with the classical FCR is underscored by their linked genomic locations, gene structure, shared extracellular domain composition, and utilization of common cytoplasmic tyrosine-based signaling elements. In contrast to the conventional FCR, however, FCRL molecules possess diverse extracellular frameworks, autonomous or dual signaling properties, and preferential B lineage expression. Most importantly, there is no strong evidence thus far to support a role for them as Ig-binding receptors. These characteristics, in addition to their identification in malignancies and autoimmune disorders, predict a fundamental role for these receptors as immunomodulatory agents in normal and subverted B lineage cells.
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Affiliation(s)
- Randall S Davis
- Division of Developmental and Clinical Immunology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294-3300, USA.
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64
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Pesesse X, Backers K, Moreau C, Zhang J, Blero D, Paternotte N, Erneux C. SHIP1/2 interaction with tyrosine phosphorylated peptides mimicking an immunoreceptor signalling motif. ACTA ACUST UNITED AC 2006; 46:142-53. [PMID: 16876851 DOI: 10.1016/j.advenzreg.2006.01.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Xavier Pesesse
- Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, Campus Erasme, Bldg C, 808 Route de Lennik, 1070 Brussels, Belgium
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65
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Burks J, Agazie YM. Modulation of alpha-catenin Tyr phosphorylation by SHP2 positively effects cell transformation induced by the constitutively active FGFR3. Oncogene 2006; 25:7166-79. [PMID: 16767162 DOI: 10.1038/sj.onc.1209728] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The Src homology 2 phosphotyrosyl phosphatase (SHP2) is a nonreceptor-type phosphatase that acts as a positive transducer of receptor Tyr kinase (RTK) signaling, particularly the Ras-REK and PI3K-Akt pathways. Recently, we have demonstrated that SHP2 is required for cell transformation induced by the constitutively active fibroblast growth factor receptor 3 (K/E-FR3) (Oncogene, 22, 6909-6918). In that study, we had detected a phosphotyrosyl protein of approximately 100 KDa (p100) in cells expressing dominant-negative SHP2 (R/E-SHP2), but its identity and relevance in SHP2-meditaed transformation was not known. Here, we report the identification of p100 as alpha-catenin, a vinculin-related protein involved in adherens junction-mediated intercellular adhesion. We show that alpha-catenin becomes Tyr phosphorylated in intercellular adhesion-dependent manner and this event is counteracted by SHP2. Substrate trapping in intact cells and immunocomplex phosphatse assays confirmed that alpha-catenin is in deed an SHP2 substrate. Tyr phosphorylation of alpha-catenin enhances its translocation to the plasma membrane and its interaction with beta-catenin, leading to enhanced actin polymerization and stabilization of adherens junction-mediated intercellular adhesion, a phenomenon commensurate with loss of the transformation phenotype. Site-directed mutagenesis studies also suggested that Tyr phosphorylation of alpha-catenin enhances its inhibitory role on cell transformation. Based on our previous work and the current report, we demonstrate that mediation of cell transformation by SHP2 is a complex process that involves modulation of the Ras-ERK and PI3K-Akt signaling pathways, intercellular adhesion, focal adhesion and actin cytoskeletal reorganization. To our knowledge, this is the first report showing regulation of alpha-catenin function by Tyr phosphorylation and its inhibitory effect on cell transformation.
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Affiliation(s)
- J Burks
- Department of Biochemistry and Molecular Pharmacology, Robert C Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506-9142, USA
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66
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Imhof D, Wavreille AS, May A, Zacharias M, Tridandapani S, Pei D. Sequence specificity of SHP-1 and SHP-2 Src homology 2 domains. Critical roles of residues beyond the pY+3 position. J Biol Chem 2006; 281:20271-82. [PMID: 16702225 DOI: 10.1074/jbc.m601047200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
A combinatorial phosphotyrosyl (pY) peptide library was screened to determine the amino acid preferences at the pY+4 to pY+6 positions for the four SH2 domains of protein-tyrosine phosphatases SHP-1 and SHP-2. Individual binding sequences selected from the library were resynthesized and their binding affinities and specificities to various SH2 domains were further evaluated by SPR studies, stimulation of SHP-1 and SHP-2 phosphatase activity, and in vitro pulldown assays. These studies reveal that binding of a pY peptide to the N-SH2 domain of SHP-2 is greatly enhanced by a large hydrophobic residue (Trp, Tyr, Met, or Phe) at the pY+4 and/or pY+5 positions, whereas binding to SHP-1 N-SH2 domain is enhanced by either hydrophobic or positively charged residues (Arg, Lys, or His) at these positions. Similar residues at the pY+4 to pY+6 positions are also preferred by SHP-1 and SHP-2 C-SH2 domains, although their influence on the overall binding affinities is much smaller compared with the N-SH2 domains. A structural model was generated to qualitatively interpret the contribution of the pY+4 and pY+5 residues to the overall binding affinity. Examination of pY motifs from known SHP-1 and SHP-2-binding proteins shows that many of the pY motifs contain a hydrophobic or positively charged residue(s) at the pY+4 and pY+5 positions.
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Affiliation(s)
- Diana Imhof
- Department of Chemistry, Ohio State University, Columbus, Ohio 43210, USA
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67
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Isnardi I, Bruhns P, Bismuth G, Fridman WH, Daëron M. The SH2 domain-containing inositol 5-phosphatase SHIP1 is recruited to the intracytoplasmic domain of human FcγRIIB and is mandatory for negative regulation of B cell activation. Immunol Lett 2006; 104:156-65. [PMID: 16406061 DOI: 10.1016/j.imlet.2005.11.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Revised: 11/22/2005] [Accepted: 11/22/2005] [Indexed: 10/25/2022]
Abstract
Murine FcgammaRIIB were demonstrated to recruit SH2 domain-containing inositol 5-phosphatases (SHIP1/2), when their ITIM is tyrosyl-phosphorylated upon co-aggregation with BCR, and SHIP1 to account for FcgammaRIIB-dependent negative regulation of murine B cell activation. Although human FcgammaRIIB share the same ITIM as murine FcgammaRIIB and similarly inhibit human B cell activation, which among the four known SH2 domain-containing (tyrosine or inositol) phosphatases is/are recruited by human FcgammaRIIB is unclear. Our recent finding that, besides the ITIM, a second tyrosine-based motif is mandatory for murine FcgammaRIIB to recruit SHIP1 challenged the possibility that human FcgammaRIIB recruit this phosphatase. Human FcgammaRIIB indeed lack this motif. Using an experimental model which enabled us to compare human FcgammaRIIB and murine FcgammaRIIB under strictly controlled conditions, we show that SHIP1 is recruited to the intracytoplasmic domain of human FcgammaRIIB and inhibits the same biological responses and intracellular signals as when recruited by murine FcgammaRIIB. Identical results were observed in murine and in human B cells. We demonstrate that SHIP is necessary for human FcgammaRIIB to inhibit BCR signaling, and cannot be replaced by SHP-1 or SHP-2. Although it contains no tyrosine, the C-terminal segment of human FcgammaRIIB was as mandatory as the tyrosine-containing C-terminal segment of murine FcgammaRIIB for SHIP1 to be recruited to the ITIM. This segment, however, did not recruit the adapters Grb2/Grap which were demonstrated to stabilize the recruitment of SHIP1 to the ITIM in murine FcgammaRIIB.
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Affiliation(s)
- Isabelle Isnardi
- Unité d' Allergologie Moléculaire et Cellulaire, Département d'Immunologie, Institut Pasteur, 75015 Paris, France
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68
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Abstract
Cell activation results from the transient displacement of an active balance between positive and negative signaling. This displacement depends in part on the engagement of cell surface receptors by extracellular ligands. Among these are receptors for the Fc portion of immunoglobulins (FcRs). FcRs are widely expressed by cells of hematopoietic origin. When binding antibodies, FcRs provide these cells with immunoreceptors capable of triggering numerous biological responses in response to a specific antigen. FcR-dependent cell activation is regulated by negative signals which are generated together with positive signals within signalosomes that form upon FcR engagement. Many molecules involved in positive signaling, including the FcRbeta subunit, the src kinase lyn, the cytosolic adapter Grb2, and the transmembrane adapters LAT and NTAL, are indeed also involved in negative signaling. A major player in negative regulation of FcR signaling is the inositol 5-phosphatase SHIP1. Several layers of negative regulation operate sequentially as FcRs are engaged by extracellular ligands with an increasing valency. A background protein tyrosine phosphatase-dependent negative regulation maintains cells in a "resting" state. SHIP1-dependent negative regulation can be detected as soon as high-affinity FcRs are occupied by antibodies in the absence of antigen. It increases when activating FcRs are engaged by multivalent ligands and, further, when FcR aggregation increases, accounting for the bell-shaped dose-response curve observed in excess of ligand. Finally, F-actin skeleton-associated high-molecular weight SHIP1, recruited to phosphorylated ITIMs, concentrates in signaling complexes when activating FcRs are coengaged with inhibitory FcRs by immune complexes. Based on these data, activating and inhibitory FcRs could be used for new therapeutic approaches to immune disorders.
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Affiliation(s)
- Marc Daëron
- Unité d'Allergologie Moléculaire et Cellulaire, Département d'Immunologie, Institut Pasteur, Paris, France
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69
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Merritt R, Hayman MJ, Agazie YM. Mutation of Thr466 in SHP2 abolishes its phosphatase activity, but provides a new substrate-trapping mutant. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2005; 1763:45-56. [PMID: 16413071 DOI: 10.1016/j.bbamcr.2005.11.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2005] [Revised: 11/08/2005] [Accepted: 11/11/2005] [Indexed: 11/21/2022]
Abstract
Most classical phosphotyrosyl phosphatases (PTPs), including the Src homology phosphotyrosyl phosphatase 2 (SHP2) possess a Thr or a Ser residue immediately C-terminal to the invariant Arg in the active site consensus motif (H/V-C-X5-R-S/T), also known as the "signature motif". SHP2 has a Thr (Thr466) at this position, but its importance in catalysis has not been investigated. By employing site-directed mutagenesis, phosphatase assays and substrate-trapping studies, we demonstrate that Thr466 is critical for the catalytic activity of SHP2. Its mutation to Ala abolishes phosphatase activity, but provides a new substrate-trapping mutant. We further show that the nucleophilic Cys459 is not involved in substrate trapping by Thr466Ala-SHP2 (T/A-SHP2). Mutation of Thr466 does not cause significant structural changes in the active site as revealed by the trapping of the epidermal growth factor receptor (EGFR), the physiological substrate of SHP2, and by orthovanadate competition experiments. Based on these results and previous other works, we propose that the role of Thr466 in the catalytic process of SHP2 could be stabilizing the sulfhydryl group of Cys459 in its reduced state, a state that enables nucleophilic attack on the phosphate moiety of the substrate. The T/A-SHP2 harbors a single mutation and specifically interacts with the EGFR. Since the nucleophilic Cys459 and the proton donor Asp425 are intact in the T/A-SAHP2, it offers an excellent starting material for solving the structure of SHP2 in complex with its physiological substrate.
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Affiliation(s)
- Rebecca Merritt
- Department of Biochemistry and Molecular Pharmacology and The Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506-9142, USA
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70
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Nielsen CH, Leslie RGQ. Regulation of B-Cell Activation by Complement Receptors and Fc Receptors. Transfus Med Hemother 2005. [DOI: 10.1159/000089121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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71
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Schmidt RE, Gessner JE. Fc receptors and their interaction with complement in autoimmunity. Immunol Lett 2005; 100:56-67. [PMID: 16125792 DOI: 10.1016/j.imlet.2005.06.022] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2005] [Revised: 06/10/2006] [Accepted: 06/24/2006] [Indexed: 01/10/2023]
Abstract
Genetic studies in mice indicate a crucial role for Fc receptors (FcR) in antibody-mediated autoimmune diseases. Like other immune regulatory receptor pairs, the FcR system is constituted by activating and inhibitory receptors that bind the same ligand, the Fc portion of Ig. Analyses of animal models have shown that the inhibitory Fc receptor, FcgammaRIIB can suppress antibody-mediated autoimmunity, whereas activating-type FcR, such as FcgammaRIII promote disease development. This review summarizes recent advances of FcR, as obtained from gene deletion studies in mice, and highlights the importance of factors that interact with FcR in autoimmunity. There is emerging evidence for an indispensable role of the complement component C5a in the regulation of FcR and the sensing of FcR-dependent effector cell responses. On the other hand, FcR might be alternatives to serum complement in the generation of C5a at sites of inflammation. Thus, FcR and complement interact with each other at the level of C5a by linking regulatory events with effector cell activities in autoimmunity. This connecting pathway is now proposed to be a promising new therapeutic target for the treatment of inflammation and autoimmune disease in both mice and humans.
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Affiliation(s)
- Reinhold E Schmidt
- Abteilung für Klinische Immunologie, Medizinische Hochschule Hannover, Labor für Molekulare Immunologie, Carl-Neuberg-Str. 1, Hannover 30625, Germany
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72
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Leslie RGQ, Marquart HV, Nielsen CH. The Role of Complement in Immune and Autoimmune Responses. Transfus Med Hemother 2005. [DOI: 10.1159/000083356] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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73
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74
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Isnardi I, Lesourne R, Bruhns P, Fridman WH, Cambier JC, Daëron M. Two Distinct Tyrosine-based Motifs Enable the Inhibitory Receptor FcγRIIB to Cooperatively Recruit the Inositol Phosphatases SHIP1/2 and the Adapters Grb2/Grap. J Biol Chem 2004; 279:51931-8. [PMID: 15456754 DOI: 10.1074/jbc.m410261200] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
FcgammaRIIB are low-affinity receptors for IgG that contain an immunoreceptor tyrosine-based inhibition motif (ITIM) and inhibit immunoreceptor tyrosine-based activation motif (ITAM)-dependent cell activation. When coaggregated with ITAM-bearing receptors, FcgammaRIIB become tyrosyl-phosphorylated and recruit the Src homology 2 (SH2) domain-containing inositol 5'-phosphatases SHIP1 and SHIP2, which mediate inhibition. The FcgammaRIIB ITIM was proposed to be necessary and sufficient for recruiting SHIP1/2. We show here that a second tyrosine-containing motif in the intracytoplasmic domain of FcgammaRIIB is required for SHIP1/2 to be coprecipitated with the receptor. This motif functions as a docking site for the SH2 domain-containing adapters Grb2 and Grap. These adapters interact via their C-terminal SH3 domain with SHIP1/2 to form a stable receptor-phosphatase-adapter trimolecular complex. Both Grb2 and Grap are required for an optimal coprecipitation of SHIP with FcgammaRIIB, but one adapter is sufficient for the phosphatase to coprecipitate in a detectable manner with the receptors. In addition to facilitating the recruitment of SHIPs, the second tyrosine-based motif may confer upon FcgammaRIIB the properties of scaffold proteins capable of altering the composition and stability of the signaling complexes generated following receptor engagement.
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Affiliation(s)
- Isabelle Isnardi
- Laboratoire d'Immunologie Cellulaire et Clinique, INSERM U255, Institut de Recherches Biomédicales des Cordeliers, 75006 Paris, France
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75
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Yasuda K, Sugita N, Kobayashi T, Yamamoto K, Yoshie H. FcgammaRIIB gene polymorphisms in Japanese periodontitis patients. Genes Immun 2004; 4:541-6. [PMID: 14647193 DOI: 10.1038/sj.gene.6364021] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Human type II low-affinity receptor for immunoglobulin G (FcgammaRII) constitutes a clustered gene family consisting of FcgammaRIIA, IIB and IIC genes. FcgammaRIIB is unique in its ability to transmit inhibitory signals in B cells via immunoreceptor tyrosine-based inhibitory motif (ITIM). B-cell activation and subsequent elevated production of IgG are the immunopathological features of inflammatory disease such as periodontitis. To determine whether an association with periodontitis susceptibility exists, genetic polymorphisms of FcgammaRIIB were examined in Japanese patients with aggressive periodontitis (AGP) and chronic periodontitis (CP), and in the race-matched healthy controls (HCs). A significant difference was observed in the distribution of FcgammaRIIB-232I/T allele (exon 5) between the AGP and HC groups, with enrichment of the 232T in the AGP group (P=0.006). In addition, the FcgammaRIIB-nt 646-184A/G allele (intron 4) distribution was significantly different between the CP and HC groups, with enrichment of the nt 646-184A in the CP group (P=0.011). These results document the association of FcgammaRIIB gene polymorphisms with susceptibility to periodontitis in the Japanese.
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Affiliation(s)
- K Yasuda
- Division of Periodontology, Department of Oral Biological Science, Niigata University, Graduate School of Medical and Dental Sciences, Gakkocho-Dori, Niigata, Japan
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76
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Cheng FC, Lin A, Feng JJ, Mizoguchi T, Takekoshi H, Kubota H, Kato Y, Naoki Y. Effects ofChlorellaon Activities of Protein Tyrosine Phosphatases, Matrix Metalloproteinases, Caspases, Cytokine Release, B and T Cell Proliferations, and Phorbol Ester Receptor Binding. J Med Food 2004; 7:146-52. [PMID: 15298760 DOI: 10.1089/1096620041224076] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
A Chlorella powder was screened using 52 in vitro assay systems for enzyme activity, receptor binding, cellular cytokine release, and B and T cell proliferation. The screening revealed a very potent inhibition of human protein tyrosine phosphatase (PTP) activity of CD45 and PTP1C with 50% inhibitory concentration (IC(50)) values of 0.678 and 1.56 microg/mL, respectively. It also showed a moderate inhibition of other PTPs, including PTP1B (IC(50) = 65.3 microg/mL) and T-cell-PTP (114 microg/mL). Other inhibitory activities and their IC(50) values included inhibition of the human matrix metalloproteinases (MMPs) MMP-1 (127 microg/mL), MMP-3 (185 microg/mL), MMP-7 (18.1 microg/mL), and MMP-9 (237 microg/mL) and the human peptidase caspases caspase 1 (300 microg/mL), caspase 3 (203 microg/mL), caspase 6 (301 microg/mL), caspase 7 (291 microg/mL), and caspase 8 (261 microg/mL), as well as release of the cytokines interleukin (IL)-1 (44.9 microg/mL), IL-2 (14.8 microg/mL), IL-4 (49.2 microg/mL), IL-6 (34.7 microg/mL), interferon-gamma (31.6 microg/mL), and tumor necrosis factor-alpha (11 microg/mL) from human peripheral blood mononuclear cells. Chlorella also inhibited B cell proliferation (16.6 microg/mL) in mouse splenocytes and T cell proliferation (54.2 microg/mL) in mouse thymocytes. The binding of a phorbol ester, phorbol 12,13-dibutyrate, to its receptors was also inhibited by Chlorella with an IC(50) of 152 microg/mL. These results reveal potential pharmacological activities that, if confirmed by in vivo studies, might be exploited for the prevention or treatment of several serious pathologies, including inflammatory disease and cancer.
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Affiliation(s)
- Fong-Chi Cheng
- MDS Pharma Services Taiwan Ltd., 158 Li-Teh Road, Taipei 112, Taiwan, Republic of China.
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77
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Kepley CL, Taghavi S, Mackay G, Zhu D, Morel PA, Zhang K, Ryan JJ, Satin LS, Zhang M, Pandolfi PP, Saxon A. Co-aggregation of FcgammaRII with FcepsilonRI on human mast cells inhibits antigen-induced secretion and involves SHIP-Grb2-Dok complexes. J Biol Chem 2004; 279:35139-49. [PMID: 15151996 DOI: 10.1074/jbc.m404318200] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Signaling through the high affinity IgE receptor FcepsilonRI on human basophils and rodent mast cells is decreased by co-aggregating these receptors to the low affinity IgG receptor FcgammaRII. We used a recently described fusion protein, GE2, which is composed of key portions of the human gamma1 and the human epsilon heavy chains, to dissect the mechanisms that lead to human mast cell and basophil inhibition through co-aggregation of FcgammaRII and FcepsilonRI. Unstimulated human mast cells derived from umbilical cord blood express the immunoreceptor tyrosine-based inhibitory motif-containing receptor FcgammaRII but not FcgammaRI or FcgammaRIII. Interaction of the mast cells with GE2 alone did not cause degranulation. Co-aggregating FcepsilonRI and FcgammaRII with GE2 1) significantly inhibited IgE-mediated histamine release, cytokine production, and Ca(2+) mobilization, 2) reduced the antigen-induced morphological changes associated with mast cell degranulation, 3) reduced the tyrosine phosphorylation of several cellular substrates, and 4) increased the tyrosine phosphorylation of the adapter protein downstream of kinase 1 (p62(dok); Dok), growth factor receptor-bound protein 2 (Grb2), and SH2 domain containing inositol 5-phosphatase (SHIP). Tyrosine phosphorylation of Dok was associated with increased binding to Grb2. Surprisingly, in non-stimulated cells, there were complexes of phosphorylated SHIP-Grb2-Dok that were lost upon IgE receptor activation but retained under conditions of Fcepsilon-Fcgamma co-aggregation. Finally, studies using mast cells from Dok-1 knock-out mice showed that IgE alone triggers degranulation supporting an inhibitory role for Dok degranulation. Our results demonstrate how human FcepsilonRI-mediated responses can be inhibited by co-aggregation with FcgammaRIIB and implicate Dok, SHIP, and Grb2 as key intermediates in regulating antigen-induced mediator release.
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Affiliation(s)
- Christopher L Kepley
- Department of Internal Medicine, Virginia Commonwealth University Health Systems, Richmond, Virginia 23298, USA.
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78
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Toyama-Sorimachi N, Tsujimura Y, Maruya M, Onoda A, Kubota T, Koyasu S, Inaba K, Karasuyama H. Ly49Q, a member of the Ly49 family that is selectively expressed on myeloid lineage cells and involved in regulation of cytoskeletal architecture. Proc Natl Acad Sci U S A 2004; 101:1016-21. [PMID: 14732700 PMCID: PMC327143 DOI: 10.1073/pnas.0305400101] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Here, we identified and characterized a Ly49 family member, designated as Ly49Q. The Ly49q gene encodes a 273-aa protein with an immunoreceptor tyrosine-based inhibitory motif (ITIM) at the N terminus of its cytoplasmic domain. We show that the ITIM of Ly49Q can recruit SHP-2 and SHP-1 in a tyrosine phosphorylation-dependent manner. In contrast to other known members of the Ly49 family, Ly49Q was found not to be expressed on NK1.1(+) cells, but instead was detectable on virtually all Gr-1(+) cells, such as myeloid precursors in bone marrow. Monocytes/macrophages also expressed low levels of Ly49Q, and the expression was enhanced by the treatment of cells with IFN-gamma. Treatment of activated macrophages with anti-Ly49Q mAb induced rapid formation of polarized actin structures, showing filopodia-like structure on one side and lamellipodial-like structure on the other side. A panel of proteins became tyrosine-phosphorylated in myeloid cells when treated with the mAb. Induction of the phosphorylation depends on the ITIM of Ly49Q. Thus, Ly49Q has unique features different from other known Ly49 family members and appears to be involved in regulation of cytoskeletal architecture of macrophages through ITIM-mediated signaling.
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Affiliation(s)
- Noriko Toyama-Sorimachi
- Department of Immune Regulation, Tokyo Medical and Dental University Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
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79
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Basic Characterization of Japanese Quail Peritoneal Macrophages Induced by Thioglycollate. J Poult Sci 2004. [DOI: 10.2141/jpsa.41.200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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80
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Frank C, Burkhardt C, Imhof D, Ringel J, Zschörnig O, Wieligmann K, Zacharias M, Böhmer FD. Effective dephosphorylation of Src substrates by SHP-1. J Biol Chem 2003; 279:11375-83. [PMID: 14699166 DOI: 10.1074/jbc.m309096200] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The protein-tyrosine phosphatase SHP-1 is a negative regulator of multiple signal transduction pathways. We observed that SHP-1 effectively antagonized Src-dependent phosphorylations in HEK293 cells. This occurred by dephosphorylation of Src substrates, because Src activity was unaffected in the presence of SHP-1. One reason for efficient dephosphorylation was activation of SHP-1 by Src. Recombinant SHP-1 had elevated activity subsequent to phosphorylation by Src in vitro, and SHP-1 variants with mutated phosphorylation sites in the C terminus, SHP-1 Y538F, and SHP-1 Y538F,Y566F were less active toward Src-generated phosphoproteins in intact cells. A second reason for efficient dephosphorylation is the substrate selectivity of SHP-1. Pull-down experiments with different GST-SHP-1 fusion proteins revealed efficient interaction of Src-generated phosphoproteins with the SHP-1 catalytic domain rather than with the SH2 domains. Phosphopeptides that correspond to good Src substrates were efficiently dephosphorylated by SHP-1 in vitro. Phosphorylated "optimal Src substrate" AEEEIpYGEFEA (where pY is phosphotyrosine) and a phosphopeptide corresponding to a recently identified Src phosphorylation site in p120 catenin, DDLDpY(296)GMMSD, were excellent SHP-1 substrates. Docking of these phosphopeptides into the catalytic domain of SHP-1 by molecular modeling was consistent with the biochemical data and explains the efficient interaction. Acidic residues N-terminal of the phosphotyrosine seem to be of major importance for efficient substrate interaction. Residues C-terminal of the phosphotyrosine probably contribute to the substrate selectivity of SHP-1. We propose that activation of SHP-1 by Src and complementary substrate specificities of SHP-1 and Src may lead to very transient Src signals in the presence of SHP-1.
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Affiliation(s)
- Carsten Frank
- Institute of Molecular Cell Biology, Medical Faculty, Faculty of Biology and Pharmacy, Friedrich Schiller University, D-07747 Jena, Germany
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81
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Crow AR, Lazarus AH. Role of Fcgamma receptors in the pathogenesis and treatment of idiopathic thrombocytopenic purpura. J Pediatr Hematol Oncol 2003; 25 Suppl 1:S14-8. [PMID: 14668633 DOI: 10.1097/00043426-200312001-00004] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Idiopathic thrombocytopenic purpura (ITP) is an autoimmune disease characterized by autoantibody-mediated platelet destruction. Platelets with associated IgG are targeted for destruction by phagocytic cells bearing Fc receptors in the reticuloendothelial system. While there are a variety of therapeutics available for this incompletely understood disease, one of the treatments of choice is infusion of intravenous immunoglobulin (IVIG). This review will discuss the pathophysiology of ITP with an emphasis on the role of Fcgamma receptors in both the pathogenesis and treatment of the disease by IVIG. Other prominent theories of the mechanisms of action of IVIG, including the role of anti-idiotype antibodies, will also be addressed.
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Affiliation(s)
- Andrew R Crow
- Department of Laboratory Medicine & Pathobiology, St. Michael's Hospital, The Canadian Blood Services, and The Toronto Platelet Immunobiology Group, Toronto, Ontario, Canada
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82
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Zhang Z, Jimi E, Bothwell ALM. Receptor Activator of NF-κB Ligand Stimulates Recruitment of SHP-1 to the Complex Containing TNFR-Associated Factor 6 That Regulates Osteoclastogenesis. THE JOURNAL OF IMMUNOLOGY 2003; 171:3620-6. [PMID: 14500659 DOI: 10.4049/jimmunol.171.7.3620] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Receptor activator of NF-kappaB ligand (RANKL) is essential for differentiation and function of osteoclasts. The negative signaling pathways downstream of RANKL are not well characterized. By retroviral transduction of RAW264.7 cells with a dominant negative Src homology 2 domain-containing phosphatase-1 (SHP-1)(C453S), we studied the role of tyrosine phosphatase SHP-1 in RANKL-induced osteoclastogenesis. Over-expression of SHP-1(C453S) significantly enhanced the number of tartrate-resistant acid phosphatase-positive multinuclear osteoclast-like cells in response to RANKL in a dose-dependent manner. RANKL induced the recruitment of SHP-1 to a complex containing TNFR-associated factor (TRAF)6. GST pull down experiments indicated that the association of SHP-1 with TRAF6 is mediated by SHP-1 lacking the two Src homology 2 domains. RANKL-stimulated IkappaB-alpha phosphorylation, IkappaB-alpha degradation and DNA binding ability of NF-kappaB were increased after over-expression of SHP-1(C453S). However, RANKL-induced phosphorylation of mitogen-activated protein kinases, extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase, was unchanged. In addition, SHP-1 regulated RANKL-stimulated tyrosine phosphorylation of p85 subunit of phosphatidylinositol 3 kinase and the phosphorylation of Akt. Increased numbers of osteoclasts contribute to severe osteopenia in Me(v)/Me(v) mice due to mutation of SHP-1. Like RAW264.7 cells expressing SHP-1(C453S), the bone marrow macrophages of Me(v)/Me(v) mice generated much more osteoclast-like cells than that of littermate controls in response to RANKL. Furthermore compared with controls, RANKL induces enhanced association of TRAF6 and RANK in both RAW264.7 cells expressing SHP-1(C453S) and bone marrow macrophages from Me(v)/Me(v) mice. Therefore, SHP-1 plays a role in signals downstream of RANKL by recruitment to the complex containing TRAF6 and these observations may help to understand the mechanism of osteoporosis in Me(v)/Me(v) mice.
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Affiliation(s)
- Zhiyuan Zhang
- Section of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA
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83
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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: 43] [Impact Index Per Article: 2.0] [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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84
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Ferjoux G, Lopez F, Esteve JP, Ferrand A, Vivier E, Vely F, Saint-Laurent N, Pradayrol L, Buscail L, Susini C. Critical role of Src and SHP-2 in sst2 somatostatin receptor-mediated activation of SHP-1 and inhibition of cell proliferation. Mol Biol Cell 2003; 14:3911-28. [PMID: 12972574 PMCID: PMC196590 DOI: 10.1091/mbc.e03-02-0069] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The G protein-coupled sst2 somatostatin receptor acts as a negative cell growth regulator. Sst2 transmits antimitogenic signaling by recruiting and activating the tyrosine phosphatase SHP-1. We now identified Src and SHP-2 as sst2-associated molecules and demonstrated their role in sst2 signaling. Surface plasmon resonance and mutation analyses revealed that SHP-2 directly associated with phosphorylated tyrosine 228 and 312, which are located in sst2 ITIMs (immunoreceptor tyrosine-based inhibitory motifs). This interaction was required for somatostatin-induced SHP-1 recruitment and activation and consequent inhibition of cell proliferation. Src interacted with sst2 and somatostatin promoted a transient Gbetagamma-dependent Src activation concomitant with sst2 tyrosine hyperphosphorylation and SHP-2 activation. These steps were abrogated with catalytically inactive Src. Both catalytically inactive Src and SHP-2 mutants abolished somatostatin-induced SHP-1 activation and cell growth inhibition. Sst2-Src-SHP-2 complex formation was dynamic. Somatostatin further induced sst2 tyrosine dephosphorylation and complex dissociation accompanied by Src and SHP-2 inhibition. These steps were defective in cells expressing a catalytically inactive Src mutant. All these data suggest that Src acts upstream of SHP-2 in sst2 signaling and provide evidence for a functional role for Src and SHP-2 downstream of an inhibitory G protein-coupled receptor.
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Affiliation(s)
- Geraldine Ferjoux
- Institut National de la Santé et de la Recherche Médicale U531, IFR31, CHU Rangueil, 31403 Toulouse, France
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85
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Haberman AM, Shlomchik MJ. Reassessing the function of immune-complex retention by follicular dendritic cells. Nat Rev Immunol 2003; 3:757-64. [PMID: 12949499 DOI: 10.1038/nri1178] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The close association of follicular dendritic cells (FDCs) and germinal-centre B cells has fostered the idea that B-cell recognition of retained antigen that is presented on the surface of FDCs is important for affinity maturation and memory B-cell development. We argue that the retention of immune complexes is not required for germinal-centre development, affinity maturation and memory B-cell maintenance. Instead, it is probable that FDCs support B-cell proliferation and differentiation in a non-specific manner. Other potential roles of immune complexes retained by FDCs are discussed.
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Affiliation(s)
- Ann M Haberman
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
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86
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Yamada T, Zhu D, Zhang K, Saxon A. Inhibition of interleukin-4-induced class switch recombination by a human immunoglobulin Fc gamma-Fc epsilon chimeric protein. J Biol Chem 2003; 278:32818-24. [PMID: 12801927 DOI: 10.1074/jbc.m304590200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Immunoglobulin E (IgE) is important in mediating human allergic diseases. We tested the hypothesis that a human Ig Fc gamma-Fc epsilon bifunctional chimeric protein, GE2, would inhibit IgE class switch recombination (CSR) by co-aggregating B-cell CD32 and CD23. Indeed, GE2 directly inhibited epsilon germ-line transcription, subsequent CSR to epsilon and IgE protein production. This CSR inhibition was dependent on CD23 binding and the phosphorylation of extracellular signal-related kinase (ERK), and it was mediated via suppression of interleukin-4-induced STAT6 phosphorylation. Treatment with PD98059, a specific inhibitor of mitogen-activated protein kinase kinase 1 (MAPKK1 (MEK1)) and MEK2 reversed the ability of GE2 to decrease CSR and STAT6 phosphorylation. GE2 stimulation induced ERK phosphorylation, whereas it did not alter the phosphorylation of c-Jun N-terminal kinase or p38 MAPK. The ability of GE2 to block human isotype switching to epsilon, in addition to its already demonstrated ability to inhibit mast cell and basophil function, suggests that it will provide an important novel benefit in the treatment of IgE-mediated diseases.
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MESH Headings
- Blotting, Western
- Cells, Cultured
- Densitometry
- Enzyme Inhibitors/pharmacology
- Flavonoids/pharmacology
- Humans
- Immunoglobulin Class Switching
- Immunoglobulin E/chemistry
- Immunoglobulin Variable Region/chemistry
- Interleukin-4/antagonists & inhibitors
- Interleukin-4/metabolism
- JNK Mitogen-Activated Protein Kinases
- Leukocytes, Mononuclear/metabolism
- MAP Kinase Kinase 1
- MAP Kinase Kinase 2
- Mitogen-Activated Protein Kinase Kinases/metabolism
- Mitogen-Activated Protein Kinases/metabolism
- Models, Biological
- Phosphorylation
- Polymerase Chain Reaction
- Protein Serine-Threonine Kinases/metabolism
- Protein Structure, Tertiary
- Protein-Tyrosine Kinases/metabolism
- RNA/metabolism
- Receptors, IgE/biosynthesis
- Receptors, IgE/metabolism
- Receptors, IgG/biosynthesis
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/metabolism
- Recombination, Genetic
- Reverse Transcriptase Polymerase Chain Reaction
- STAT6 Transcription Factor
- Time Factors
- Trans-Activators/metabolism
- Transcription, Genetic
- p38 Mitogen-Activated Protein Kinases
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Affiliation(s)
- Takechiyo Yamada
- Hart and Louis Laboratory, Division of Clinical Immunology, Department of Medicine, UCLA School of Medicine, California 90095-1680, USA.
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87
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Agramonte-Hevia J, Hallal C, Garay-Canales C, Guerra-Araiza C, Camacho-Arroyo I, Ortega Soto E. 1alpha, 25-dihydroxy-vitamin D3 alters Syk activation through FcgammaRII in monocytic THP-1 cells. J Cell Biochem 2003; 89:1056-76. [PMID: 12874838 DOI: 10.1002/jcb.10575] [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: 11/06/2022]
Abstract
In monocytes and macrophages, activation of the tyrosine kinase Syk is an essential step in the biochemical cascade linking aggregation of receptors for immunoglobulin G (FcgammaR) to initiation of effector functions. An increase in Syk activation during differentiation of myeloid cells by different agents has been reported. We studied the activation state of Syk in response to FcgammaRII crosslinking in monocytic cells before and after in vitro differentiation with 1alpha, 25-dihydroxy-vitamin D3. We show here that while in undifferentiated THP-1 cells clustering of FcgammaRII induces significant phosphorylation and activation of Syk, in THP-1 cells differentiated in vitro by 1alpha, 25-dihydroxy-vitamin D3, FcgammaRII crosslinking induced a decrease in Syk activity. In vitro differentiation did not induce changes in the expression of FcgammaRII isoforms. The observed effect on Syk activation though FcgammaRII could be mediated by differentiation-induced changes in the expression and basal activation level of Syk, as well as changes in the association of Syk with the tyrosine phosphatase SHP-1. These results suggest that the biochemical signaling pathways induced by FcgammaRII could be dependent on the differentiation state of the cell.
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Affiliation(s)
- José Agramonte-Hevia
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Cuidad Universitaria, D. F., 04510 México
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88
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Crow AR, Song S, Freedman J, Helgason CD, Humphries RK, Siminovitch KA, Lazarus AH. IVIg-mediated amelioration of murine ITP via FcgammaRIIB is independent of SHIP1, SHP-1, and Btk activity. Blood 2003; 102:558-60. [PMID: 12649142 DOI: 10.1182/blood-2003-01-0023] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
It has been established that amelioration of murine immune thrombocytopenia purpura (ITP) by IVIg is dependent on the inhibitory receptor FcgammaRIIB. Co-cross-linking of the FcgammaRIIB with the B-cell receptor complex or with FcepsilonRI in mast cells results in cell inhibition, which is mediated by recruitment of the inositol phosphatase SHIP1 to the cytoplasmic tail of the FcgammaR. The FcgammaRIIB can also associate with protein tyrosine phosphatase SHP-1 as a potential secondary target of the receptor. Alternatively, homoaggregation of FcgammaRIIB can induce a proapoptotic state in B cells that is dependent on the presence of Bruton tyrosine kinase (Btk), a kinase also expressed in monocytes. We sought to determine if these signaling pathways may direct IVIg-mediated FcgammaRIIB-dependent regulation of in vivo monocyte function in a murine model of ITP in which IVIg functions in an FcgammaRIIB-dependent manner. We demonstrate that mice deficient in SHIP1, SHP-1, and Btk respond to the ameliorating effects of IVIg with the same kinetics as control mice. We conclude that IVIgmediated inhibitory pathways operating via monocyte FcgammaRIIB may involve a transmembrane signaling pathway different from that of B cells.
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MESH Headings
- Agammaglobulinaemia Tyrosine Kinase
- Animals
- Antigens, CD/physiology
- Autoimmune Diseases/enzymology
- Autoimmune Diseases/immunology
- Autoimmune Diseases/therapy
- B-Lymphocytes/enzymology
- B-Lymphocytes/immunology
- Immunoglobulins, Intravenous/therapeutic use
- Intracellular Signaling Peptides and Proteins
- Mast Cells/immunology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Models, Animal
- Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases
- Phosphoric Monoester Hydrolases/deficiency
- Phosphoric Monoester Hydrolases/genetics
- Phosphoric Monoester Hydrolases/physiology
- Phosphorylation
- Protein Processing, Post-Translational
- Protein Tyrosine Phosphatase, Non-Receptor Type 6
- Protein Tyrosine Phosphatases/deficiency
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases/physiology
- Protein-Tyrosine Kinases/deficiency
- Protein-Tyrosine Kinases/genetics
- Protein-Tyrosine Kinases/physiology
- Purpura, Thrombocytopenic, Idiopathic/enzymology
- Purpura, Thrombocytopenic, Idiopathic/immunology
- Purpura, Thrombocytopenic, Idiopathic/therapy
- Receptors, IgG/physiology
- Signal Transduction/physiology
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Affiliation(s)
- Andrew R Crow
- Transfusion Medicine Research, St Michael's Hospital, Toronto, ON, Canada
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89
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Abstract
Lupus is a chronic autoimmune inflammatory disease with complex clinical manifestations. In humans, lupus, also known as systemic lupus erythematosus (SLE), affects between 40 and 250 individuals, mostly females, in each 100 000 of the population. There are also a number of murine models of lupus widely used in studies of the genetics, immunopathology, and treatment of lupus. Human patients and murine models of lupus manifest a wide range of immunological abnormalities. The most pervasive of these are: (1) the ability to produce pathogenic autoantibodies; (2) lack of T- and B-lymphocyte regulation; and (3) defective clearance of autoantigens and immune complexes. This article briefly reviews immunological abnormalities and disease mechanisms characteristic of lupus autoimmunity and highlight recent studies on the use of gene therapy to target these abnormalities.
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Affiliation(s)
- R A Mageed
- Department of Immunology and Molecular Pathology, Royal Free and University College School of Medicine, London, UK
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90
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Agazie YM, Hayman MJ. Development of an efficient "substrate-trapping" mutant of Src homology phosphotyrosine phosphatase 2 and identification of the epidermal growth factor receptor, Gab1, and three other proteins as target substrates. J Biol Chem 2003; 278:13952-8. [PMID: 12582165 DOI: 10.1074/jbc.m210670200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Src homology containing phosphotyrosine phosphatase 2 (SHP2) is a positive effector of growth factor, cytokine, and integrin signaling. However, neither its physiological substrate nor its mechanism of action in tyrosine kinase signaling has been demonstrated. We reasoned that the identification of physiological substrates of SHP2 would be a stepping stone in elucidating its mechanism of action, and, thus, we constructed a potent trapping mutant of SHP2. Surprisingly, the frequently used Asp to Ala substitution did not give rise to a trapping mutant. However, we were able to develop an efficient trapping mutant of SHP2 by introducing Asp to Ala and Cys to Ser double mutations. The double mutant (DM) protein identified the epidermal growth factor receptor (EGFR), the Grb2 binder 1, and three other, as yet unidentified, phosphotyrosyl proteins as candidate physiological substrates. Given that substrate trapping occurred in intact cells and that the interaction was very specific, it is highly likely that EGFR and Gab1 represent physiological SHP2 substrates. Therefore, the DM protein would serve as an important tool in future SHP2 studies, including identification of p190, p150, and p90.
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Affiliation(s)
- Yehenew M Agazie
- Department of Molecular Genetics and Microbiology, State University of New York at Stony Brook, 11794-5222, USA
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91
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Hanson EM, Dickensheets H, Qu CK, Donnelly RP, Keegan AD. Regulation of the dephosphorylation of Stat6. Participation of Tyr-713 in the interleukin-4 receptor alpha, the tyrosine phosphatase SHP-1, and the proteasome. J Biol Chem 2003; 278:3903-11. [PMID: 12459556 DOI: 10.1074/jbc.m211747200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Signal transducer and activator of transcription 6 (Stat6) plays an important role in interleukin (IL)-4-induced responses. To analyze the regulation of Stat6 phosphorylation, cells were cultured in the continuous presence of IL-4 or after a pulse and washout. In the continual presence of IL-4, Stat6 remained phosphorylated for an extended period. After IL-4 removal and inhibition of the Janus family kinase, tyrosine-phosphorylated Stat6 decayed at a rate dependent upon the length of IL-4 stimulation. The decay of tyrosine-phosphorylated Stat6 was similar in the presence or absence of either cycloheximide or actinomycin D. In the absence of functional Src homology-containing phosphatase-1 (SHP-1), the early loss of tyrosine-phosphorylated Stat6 was substantially reduced. Furthermore, the rate of loss of tyrosine-phosphorylated Stat6 in cells expressing a mutation of the human IL-4 receptor alpha in the immunoreceptor tyrosine-based inhibitory motif sequence (Y5F) was dramatically decreased compared with wild-type cells. The early rate of decay was similar in the presence or absence of MG132, an inhibitor of the proteasome, but the later rate of decay was decreased 5-fold. These results suggest that the loss of tyrosine phosphorylation of Stat6 is regulated by the action of SHP-1 and the proteasome but is not dependent on new protein synthesis.
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Affiliation(s)
- Erica M Hanson
- Department of Immunology, Holland Laboratory, American Red Cross, Rockville, Maryland 20855, USA
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92
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Ma XZ, Jin T, Sakac D, Fahim S, Zhang X, Katsman Y, Bali M, Branch DR. Abnormal splicing of SHP-1 protein tyrosine phosphatase in human T cells. Implications for lymphomagenesis. Exp Hematol 2003; 31:131-42. [PMID: 12591278 DOI: 10.1016/s0301-472x(02)01025-1] [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
OBJECTIVE SHP-1 protein tyrosine phosphatase has been implicated in suppressing B-lymphocyte and myeloid cell malignancies; however, there are little data on this role of SHP-1 in T-lymphocyte malignancies. We examined malignant human T cells to identify any abnormalities of SHP-1 that would support a role for this molecule in suppressing T lymphomagenesis. MATERIALS AND METHODS Human T-lymphocyte cell lines and primary blood cells were used to examine the expression of SHP-1 mRNA and protein. Reverse transcriptase polymerase chain reaction was used to amplify particular portions of the SHP-1 mRNA for cloning and sequencing. Gene transfer was used to examine the effects of SHP-1 on cell growth and morphology. Glutathione S-transferase (GST) fusion proteins were generated and used to determine SHP-1-associated proteins. RESULTS Leukemia- and lymphoma-derived cell lines were identified that did not express SHP-1 protein. Examination of the mRNA from these and other T-cell lines, and from normal peripheral blood mononuclear cells (PBMCs), revealed three distinct transcripts by restriction enzymes, reverse transcriptase polymerase chain reaction, and Southern blot analysis. In addition to the expected wild-type transcript, two novel transcripts were identified. One was a deletion transcript found only in Jurkat leukemia-derived cells, predicted to encode for a 7-kDa protein containing most of the amino-terminal SH2 domain. The second contained an 88-nucleotide insert that is the unspliced second intron resulting in a frame shift and the formation of a noncoding transcript. This mRNA was found in all cells examined but was the only transcript detected in the cell lines lacking SHP-1 protein. Expressing wild-type SHP-1 in these cell lines resulted in a change in the morphology of the cells with a concomitant decrease in their growth. GST fusion constructs showed the 7-kDa variant able to associate with an identical array of proteins as wild-type SHP-1, suggesting that it could compete with the wild-type SHP-1 for substrates. This protein was detectable in the cell line expressing its corresponding mRNA and was able to induce significant changes in cell morphology when transfected into a cell line expressing wild-type SHP-1; however, it did not induce any changes in cell growth. CONCLUSIONS These data are the first to show the existence of multiple transcripts of SHP-1 in human transformed T lymphocytes and normal PBMCs and supports previous work showing that alternate forms of SHP-1 mRNA are a common finding in other cells. We also show the lack of splicing out of an intron as a novel mechanism of regulation of SHP-1 protein expression in both normal and transformed T cells. Moreover, we provide the first evidence showing a protein product detectable in cells that is translated from an alternatively spliced form of SHP-1 mRNA, a variant truncated SHP-1 protein having potential biologic relevance. This report provides evidence supporting the concept that SHP-1 can negatively regulate growth of malignant human T cells and that lack of SHP-1 protein or function may be associated with lymphomagenesis.
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Affiliation(s)
- Xue-Zhong Ma
- Department of Medicine and Institute of Medical Science, University of Toronto, 67 College Street, Toronto M5G 2M1, Ontario, Canada
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93
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Abstract
We present a hypothesis regarding the mode of induction of the inhibitory phosphatases SHP-1 and SHIP in hematopoietic cells. One mode is a general one in which the phosphatase regulates but does not abort signal transduction and biology. Regulator phosphatases are induced by directly or indirectly engaging the amino acid motifs present in the activating receptor, and act to control the biochemical and biological output. The other mode of induction is a specific one, which critically involves paired co-clustering of activating and inhibitory receptors. Phosphatases working in this way act only under conditions of paired co-clustering of activating and inhibitory receptors, and directly bind amino acid motifs present in the inhibitory receptor. However, this mode of induction is apparently more efficient, as cellular activation is completely aborted. This review presents several examples of each mode of inhibition and speculates on their mechanisms.
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Affiliation(s)
- K M Coggeshall
- The Oklahoma Medical Research Foundation, Program in Immunobiology, 825 N.E. 13th St., Oklahoma City, OK 73104, USA.
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94
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Duchene J, Schanstra JP, Pecher C, Pizard A, Susini C, Esteve JP, Bascands JL, Girolami JP. A novel protein-protein interaction between a G protein-coupled receptor and the phosphatase SHP-2 is involved in bradykinin-induced inhibition of cell proliferation. J Biol Chem 2002; 277:40375-83. [PMID: 12177051 DOI: 10.1074/jbc.m202744200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mitogenic G protein-coupled receptor (GPCR) signaling has been extensively studied. In contrast, little is known about anti-mitogenic GPCR signaling. We show here that anti-mitogenic signaling of a GPCR, the bradykinin B2 receptor, involves a novel direct protein-protein interaction. The antiproliferative effect of bradykinin was accompanied by a transient increase in protein-tyrosine phosphatase activity. Using surface plasmon resonance analysis, we observed that an immunoreceptor tyrosine-based inhibitory motif (ITIM) located in the C-terminal part of the B2 receptor interacted specifically with the protein-tyrosine phosphatase SHP-2. The interaction was confirmed in primary culture renal mesangial cells by co-immunoprecipitation of a B2 receptor.SHP-2 complex. The extent of the interaction was transiently increased by stimulation with bradykinin, which was accompanied by an increase in specific SHP-2 phosphatase activity. Mutational analysis of the key ITIM residue confirmed that the B2 receptor ITIM sequence is required for interaction with SHP-2, SHP-2 activation, and the anti-mitogenic effect of bradykinin. Finally, in mesangial cells transfected with a dominant-negative form of SHP-2, bradykinin lost the ability to inhibit cell proliferation. These observations demonstrate that bradykinin inhibits cell proliferation by a novel mechanism involving a direct protein-protein interaction between a GPCR (the B2 receptor) and SHP-2.
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Affiliation(s)
- Johan Duchene
- INSERM U388, Institut Louis Bugnard, Institute Fédératif de Recherche 31, Centre Hospitalier Universitaire Rangueil, 1 Avenue J. Poulhes, 31403 Toulouse Cedex, France
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95
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Zhuang Q, Bisotto S, Fixman ED, Mazer B. Suppression of IL-4- and CD40-induced B-lymphocyte activation by intravenous immunoglobulin is not mediated through the inhibitory IgG receptor FcgammaRIIb. J Allergy Clin Immunol 2002; 110:480-3. [PMID: 12209098 DOI: 10.1067/mai.2002.127284] [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: 11/22/2022]
Abstract
BACKGROUND Intravenous immunoglobulin (IVIG) has been used extensively in the treatment of autoimmune and allergic diseases, but the precise mechanism behind its efficacy remains unclear. Ligation of the low-affinity IgG Fc receptor FcgammaRIIb can inhibit B-lymphocyte activation. Our laboratory has shown that IVIG suppresses proliferation and IgE production by human B cells stimulated with IL-4 and anti-CD40 antibodies. OBJECTIVE We sought to determine whether the regulatory action of IVIG is mediated through binding FcgammaRIIb, phosphorylation of the receptor, and induction of phosphatases, including SH2-containing inositol-5'-phosphatase. METHODS All experiments were performed on human tonsillar B cells. Phenotyping was performed by means of flow cytometry. Cells were cultured with IL-4 and anti-CD40 antibodies with or without IVIG (10 mg/mL), and FCgammaRIIb receptor activation and phosphorylation were measured by means of Western blot analysis. RESULTS FcgammaRIIb was the predominant isoform of Fcgamma receptor expressed on tonsillar B cells, and preincubation with IVIG failed to block binding of FcgammaRIIb antibody. Anti-FcgammaRIIb antibodies did not reverse inhibition of B-cell proliferation or IgE production by IVIG. Treatment of stimulated B lymphocytes with IVIG for 1 to 60 minutes did not change the global protein tyrosine phosphorylation pattern, except for tyrosine phosphorylation of an unidentified 30-kd protein. We directly examined tyrosine phosphorylation of FcgammaRIIb and its downstream-associated phosphatase, SH2-containing inositol-5'-phosphatase. Both remained unchanged after IVIG treatment, as did other related phosphatases. CONCLUSION These data argue against the involvement of FcgammaRIIb in the inhibition of CD40/IL-4-induced B-cell activation by IVIG.
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Affiliation(s)
- Qianli Zhuang
- Division of Allergy and Immunology, Montreal Children's Hospital, McGill University, Canada
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96
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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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97
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Affiliation(s)
- Toshiyuki Takai
- Department of Experimental Immunology, Japan Science and Technology Corporation, Institute of Development, Ageing and Cancer, Tohoku University, Seiryo, Sendai, Japan.
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98
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Nielsen CH, Leslie RGQ. Complement’s participation in acquired immunity. J Leukoc Biol 2002. [DOI: 10.1189/jlb.72.2.249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Claus Henrik Nielsen
- Institute for Inflammation Research, Rigshospitalet, University Hospital Copenhagen; and
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99
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Davis RS, Dennis G, Kubagawa H, Cooper MD. Fc receptor homologs (FcRH1-5) extend the Fc receptor family. Curr Top Microbiol Immunol 2002; 266:85-112. [PMID: 12014205 DOI: 10.1007/978-3-662-04700-2_7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- R S Davis
- Division of Hematology/Oncology, Department of Medicine, University of Alabama at Birmingham, AL 35294-3300, USA
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100
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Yusa SI, Catina TL, Campbell KS. SHP-1- and phosphotyrosine-independent inhibitory signaling by a killer cell Ig-like receptor cytoplasmic domain in human NK cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:5047-57. [PMID: 11994457 DOI: 10.4049/jimmunol.168.10.5047] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Killer cell Ig-like receptors (KIR) are MHC class I-binding immunoreceptors that can suppress activation of human NK cells through recruitment of the Src homology 2-containing protein tyrosine phosphatase-1 (SHP-1) to two immunoreceptor tyrosine-based inhibitory motifs (ITIMs) in their cytoplasmic domains. KIR2DL4 (2DL4; CD158d) is a structurally distinct member of the KIR family, which is expressed on most, if not all, human NK cells. 2DL4 contains only one ITIM in its cytoplasmic domain and an arginine in its transmembrane region, suggesting both inhibitory and activating functions. While 2DL4 can activate IFN-gamma production, dependent upon the transmembrane arginine, the function of the single ITIM of 2DL4 remains unknown. In this study, tandem ITIMs of KIR3DL1 (3DL1) and the single ITIM of 2DL4 were directly compared in functional and biochemical assays. Using a retroviral transduction method, we show in human NK cell lines that 1) the single ITIM of 2DL4 efficiently inhibits natural cytotoxicity responses; 2) the phosphorylated single ITIM recruits SHP-2 protein tyrosine phosphatase, but not SHP-1 in NK cells; 3) expression of dominant-negative SHP-1 does not block the ability of 2DL4 to inhibit natural cytotoxicity; 4) surprisingly, mutation of the tyrosine within the single ITIM does not completely abolish inhibitory function; and 5) this correlates with weak SHP-2 binding to the mutant ITIM of 2DL4 in NK cells and a corresponding nonphosphorylated ITIM peptide in vitro. These results reveal new aspects of the KIR-inhibitory pathway in human NK cells, which are SHP-1 and phosphotyrosine independent.
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MESH Headings
- Amino Acid Motifs/genetics
- Amino Acid Motifs/immunology
- Amino Acid Sequence
- Cell Culture Techniques/methods
- Cell Line
- Cytoplasm/enzymology
- Cytoplasm/immunology
- Cytoplasm/metabolism
- Cytotoxicity Tests, Immunologic
- Cytotoxicity, Immunologic/genetics
- Humans
- Intracellular Signaling Peptides and Proteins
- Killer Cells, Natural/enzymology
- Killer Cells, Natural/immunology
- Killer Cells, Natural/metabolism
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Peptide Fragments/genetics
- Peptide Fragments/immunology
- Peptide Fragments/metabolism
- Phosphorylation
- Phosphotyrosine/physiology
- Protein Binding/genetics
- Protein Binding/immunology
- Protein Phosphatase 1
- Protein Structure, Tertiary/physiology
- Protein Tyrosine Phosphatase, Non-Receptor Type 11
- Protein Tyrosine Phosphatase, Non-Receptor Type 6
- Protein Tyrosine Phosphatases/biosynthesis
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases/metabolism
- Protein Tyrosine Phosphatases/physiology
- Receptors, Immunologic/biosynthesis
- Receptors, Immunologic/genetics
- Receptors, Immunologic/metabolism
- Receptors, Immunologic/physiology
- Receptors, KIR
- Receptors, KIR2DL4
- Receptors, KIR3DL1
- SH2 Domain-Containing Protein Tyrosine Phosphatases
- Signal Transduction/immunology
- Tumor Cells, Cultured
- Vaccinia virus/enzymology
- Vaccinia virus/genetics
- src Homology Domains/immunology
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Affiliation(s)
- Sei-ichi Yusa
- Division of Basic Science, Institute for Cancer Research, Fox Chase Cancer Center, 7701 Burholme Avenue, Philadelphia, PA 19111, USA
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