201
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Li W, Ma Y, Zhao Y. Penta-coordinated phosphorus structure analysis on kinases. ACTA ACUST UNITED AC 2004. [DOI: 10.1007/bf02990903] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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202
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Affiliation(s)
- Ulrich Blank
- INSERM E 0225, Bichat Medical School, 16 rue Henri Huchard, BP 416, 75870 Cedex 18, France
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203
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Hernandez-Hansen V, Smith AJ, Surviladze Z, Chigaev A, Mazel T, Kalesnikoff J, Lowell CA, Krystal G, Sklar LA, Wilson BS, Oliver JM. Dysregulated FcepsilonRI signaling and altered Fyn and SHIP activities in Lyn-deficient mast cells. THE JOURNAL OF IMMUNOLOGY 2004; 173:100-12. [PMID: 15210764 DOI: 10.4049/jimmunol.173.1.100] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Studies in B cells from Lyn-deficient mice have identified Lyn as both a kinetic accelerator and negative regulator of signaling through the BCR. The signaling properties of bone marrow-derived mast cells from Lyn(-/-) mice (Lyn(-/-) BMMCs) have also been explored, but their signaling phenotype remains controversial. We confirm that Lyn(-/-) BMMCs release more beta-hexosaminidase than wild-type BMMCs following FcepsilonRI cross-linking and show that multiple mast cell responses to FcepsilonRI cross-linking (the phosphorylation of receptor subunits and other proteins, the activation of phospholipase Cgamma isoforms, the mobilization of Ca(2+), the synthesis of phosphatidylinositol 3,4,5-trisphosphate, the activation of the alpha(4)beta(1) integrin, VLA-4) are slow to initiate in Lyn(-/-) BMMCs, but persist far longer than in wild-type cells. Mechanistic studies revealed increased basal as well as stimulated phosphorylation of the Src kinase, Fyn, in Lyn(-/-) BMMCs. Conversely, there was very little basal or stimulated tyrosine phosphorylation or activity of the inositol phosphatase, SHIP, in Lyn(-/-) BMMCs. We speculate that Fyn may substitute (inefficiently) for Lyn in signal initiation in Lyn(-/-) BMMCs. The loss of SHIP phosphorylation and activity very likely contributes to the increased levels of phosphatidylinositol 3,4,5-trisphosphate and the excess FcepsilonRI signaling in Lyn(-/-) BMMCs. The unexpected absence of the transient receptor potential channel, Trpc4, from Lyn(-/-) BMMCs may additionally contribute to their altered signaling properties.
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Affiliation(s)
- Valerie Hernandez-Hansen
- Department of Pathology and Cancer Research and Treatment Center, University of New Mexico School of Medicine, CRF 205, 2325 Camino De Salud, Albuquerque, NM 87131, USA
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204
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Kraft S, Rana S, Jouvin MH, Kinet JP. The role of the FcepsilonRI beta-chain in allergic diseases. Int Arch Allergy Immunol 2004; 135:62-72. [PMID: 15316148 DOI: 10.1159/000080231] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The high affinity receptor for IgE, FcepsilonRI, is a multimeric surface receptor that is expressed exclusively as a tetramer on rodent cells, but exists as a tetramer or trimer on human cells. The tetrameric form is expressed on effector cells of allergic responses such as mast cells and basophils and is composed of an IgE-binding alpha-subunit, a beta-subunit and a gamma-subunit dimer. Complexes lacking the beta-subunit are found on human antigen-presenting cells. On mast cells and basophils, FcepsilonRI is essential for IgE-mediated acute allergic reactions. Crosslinking of FcepsilonRI by IgE and multivalent antigen induces a signaling cascade that culminates in the release of preformed mediators and the synthesis of lipid mediators and cytokines. The beta-subunit functions as an amplifier of FcepsilonRI expression and signaling. As a consequence, strongly enhanced mast cell effector functions and in vivo allergic reactions can be observed in the presence of FcepsilonRIbeta. In contrast, a truncated beta-isoform (betaT) that is produced by alternative splicing acts as an inhibitor of FcepsilonRI surface expression. Thus, by producing two proteins with antagonistic functions, the FcepsilonRIbeta gene could serve as a potent regulator of allergic responses. In addition, the genomic region encompassing the beta-chain has been linked to atopy and a number of polymorphisms within the FcepsilonRIbeta gene are associated with various atopic diseases. It remains to be elucidated how these polymorphisms might affect the allergic phenotype. These functions of the beta-chain together with the described genetic linkages to atopy make it a candidate for a role in the pathophysiology of allergic diseases.
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Affiliation(s)
- Stefan Kraft
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA
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205
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Abstract
Cells of the immune system carry out diverse functions that are controlled by surface receptors for antigen, costimulatory molecules, cytokines, chemokines, and other ligands. A shared feature of signal transduction downstream of most receptors on immune cells, as in nonhematopoietic cell types, is the activation of phosphoinositide 3-kinase (PI3K). The mechanism by which this common signaling event is elicited by distinct receptors and contributes to unique functional outcomes is an intriguing puzzle. Understanding how specificity is achieved in PI3K signaling is of particular significance because altered regulation of this pathway is observed in many disease states, including leukemia and lymphoma. Here we review recent advances in the understanding of PI3K signaling mechanisms in different immune cells and receptor systems. We emphasize the concept that PI3K and its products are components of complex networks of interacting proteins and second messengers, rather than simple links in linear signaling cascades.
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Affiliation(s)
- Jonathan A Deane
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 92697, USA.
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206
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Pandey V, Mihara S, Fensome-Green A, Bolsover S, Cockcroft S. Monomeric IgE stimulates NFAT translocation into the nucleus, a rise in cytosol Ca2+, degranulation, and membrane ruffling in the cultured rat basophilic leukemia-2H3 mast cell line. THE JOURNAL OF IMMUNOLOGY 2004; 172:4048-58. [PMID: 15034016 DOI: 10.4049/jimmunol.172.7.4048] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mast cells are key regulators in allergy and inflammation, and release histamine, cytokines, and other proinflammatory mediators. In the classical view, IgE acts merely to prime mast cells, attaching to FcepsilonRs but not evoking any cell signaling response until cross-linked by the presence of a multivalent allergen. However, several recent studies have reported that IgE alone can promote cell survival and cytokine production in the absence of cross-linking by allergen. In this study we demonstrate that acute addition of monomeric IgE elicits a wide spectrum of responses in the rat basophilic leukemia-2H3 mast cell line, including activation of phospholipases Cgamma and D, a rise in cytosol Ca(2+), NFAT translocation, degranulation, and membrane ruffling within minutes. Calcium transients persist for hours as long as IgE is present resulting in the maintained translocation of the transcription factor NFAT to the nucleus. Removal of IgE reverses the signaling processes. Our results indicate that, far from simply preparing the cells for a response to allergen, monomeric IgE can stimulate signaling pathways that lead to degranulation, membrane ruffling, and NFAT translocation. The mechanism of activation is likely to be via aggregation of the FcepsilonR1 because activation by IgE can be inhibited with monovalent hapten.
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Affiliation(s)
- Vinita Pandey
- Department of Physiology, University College London, London, United Kingdom
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207
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Zompi S, Gu H, Colucci F. The absence of Grb2-associated binder 2 (Gab2) does not disrupt NK cell development and functions. J Leukoc Biol 2004; 76:896-903. [PMID: 15240750 DOI: 10.1189/jlb.0304179] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Scaffolding molecules bind simultaneously and link together various components of signal-transduction pathways. Grb2-associated binder 2 (Gab2) is a scaffolding protein required for FcgammaR-initiated allergic responses in mast cells and FcgammaR-mediated phagocytosis in macrophages, where it links IgE and IgG receptors to the phosphatidylinositol-3 kinase (PI-3K) pathway. The FcgammaR expressed by natural killer (NK) cells triggers antibody-dependent cellular cytotoxicity (ADCC). We show here that mouse NK cells express Gab2 and that although PI-3K was required for ADCC, this FcgammaR-mediated function was normal in Gab2-/- NK cells. Moreover, NK cell development, spontaneous cytotoxicity, and responses to and production of cytokines were not perturbed in Gab2-/- mice. Considering the striking differences between the signaling requirements of FcgammaR in macrophages and NK cells, our findings suggest that the organization of signal transduction downstream of the same FcR can be cell type-specific. Conversely, Gab family members Gab1, Gab2, and Gab3 may play specific roles in different leukocytes. As pharmacological targeting of Gab2 in mast cells is a potential strategy to treat allergy, our results suggest prudence, as NK cells may participate in IgE-mediated anaphylaxis in a Gab2-independent manner.
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Affiliation(s)
- Simona Zompi
- Cytokines and Lymphoid Development Unit, Department of Immunology, The Pasteur Institute, Paris, France
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208
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Andrade MVM, Hiragun T, Beaven MA. Dexamethasone Suppresses Antigen-Induced Activation of Phosphatidylinositol 3-Kinase and Downstream Responses in Mast Cells. THE JOURNAL OF IMMUNOLOGY 2004; 172:7254-62. [PMID: 15187100 DOI: 10.4049/jimmunol.172.12.7254] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Dexamethasone and other glucocorticoids suppress FcepsilonRI-mediated release of inflammatory mediators from mast cells. Suppression of cytokine production is attributed to repression of cytokine gene transcription but no mechanism has been described for the suppression of degranulation. We show that therapeutic concentrations of dexamethasone inhibit intermediate signaling events, in particular the activation of phosphatidylinositol (PI)3-kinase and downstream signaling events that lead to degranulation in rat basophilic leukemia 2H3 cells. This inhibitory action is mediated via the glucocorticoid receptor and is not apparent when cells are stimulated via Kit in a mouse bone marrow-derived mast cell line. The primary perturbation appears to be the failure of the regulatory p85 subunit of PI3-kinase to engage with the adaptor protein Grb2-associated binder 2 leading to suppression of phosphorylation of phospholipase Cgamma2, the calcium signal, and degranulation. Suppression of PI3-kinase activation by dexamethasone may also contribute to reduced cytokine production because the PI3-kinase inhibitor LY294002, like dexamethasone, inhibits Ag-induced transcription of cytokine genes as well as degranulation.
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Affiliation(s)
- Marcus V M Andrade
- Laboratory of Molecular Immunology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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209
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Podar K, Mostoslavsky G, Sattler M, Tai YT, Hayashi T, Catley LP, Hideshima T, Mulligan RC, Chauhan D, Anderson KC. Critical Role for Hematopoietic Cell Kinase (Hck)-mediated Phosphorylation of Gab1 and Gab2 Docking Proteins in Interleukin 6-induced Proliferation and Survival of Multiple Myeloma Cells. J Biol Chem 2004; 279:21658-65. [PMID: 15010462 DOI: 10.1074/jbc.m305783200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Interleukin-6 (LI-6) is a known growth and survival factor in multiple myeloma via activation of extracellular signal-regulated kinase and phosphatidylinositol 3-kinase signaling cascade. In this report we show that Grb2-associated binder (Gab) family adapter proteins Gab1 and Gab2 are expressed by multiple myeloma cells; and that interleukin-6 induces their tyrosine phosphorylation and association with downstream signaling molecules. We further demonstrate that these events are Src family tyrosine kinase-dependent and specifically identify the role of hematopoietic cell kinase (Hck) as a new Gab family adapter protein kinase. Conversely, inhibition of Src family tyrosine kinases by the pyrazolopyrimidine PP2, as in kinase-inactive Hck mutants, significantly reduces IL-6-triggered activation of extracellular signal-regulated kinase and AKT-1, leading to significant reduction of multiple myeloma cell proliferation and survival. Taken together, these results delineate a key role for Hck-mediated phosphorylation of Gab1 and Gab2 docking proteins in IL-6-induced proliferation and survival of multiple myeloma cells and identify tyrosine kinases and downstream adapter proteins as potential new therapeutic targets in multiple myeloma.
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Affiliation(s)
- Klaus Podar
- Department of Medical Oncology, Jerome Lipper Multiple Myeloma Center, Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA
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210
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Van Etten RA. Mechanisms of transformation by the BCR-ABL oncogene: new perspectives in the post-imatinib era. Leuk Res 2004; 28 Suppl 1:S21-8. [PMID: 15036938 DOI: 10.1016/j.leukres.2003.10.005] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Since its introduction less than 3 years ago, imatinib mesylate (STI571) has altered the entire approach to the therapy of patients with chronic myeloid leukemia (CML). In addition to its impact on clinical practice, imatinib has also increased the focus of basic and translational CML research on enhancing the cellular effects of imatinib and preventing and overcoming resistance to the drug. Here, I summarize some recent advances in our understanding of the regulatory and signaling mechanisms of Bcr-Abl, with an emphasis on therapeutic implications.
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MESH Headings
- Benzamides
- Cell Transformation, Neoplastic/genetics
- Fusion Proteins, bcr-abl/genetics
- Fusion Proteins, bcr-abl/metabolism
- Genes, abl/physiology
- Humans
- Imatinib Mesylate
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/etiology
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Piperazines/therapeutic use
- Pyrimidines/therapeutic use
- Signal Transduction
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Affiliation(s)
- Richard A Van Etten
- Molecular Oncology Research Institute, Tufts-New England Medical Center, 750 Washington Street, Boston, MA 02111, USA.
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211
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Roumiantsev S, Krause DS, Neumann CA, Dimitri CA, Asiedu F, Cross NCP, Van Etten RA. Distinct stem cell myeloproliferative/T lymphoma syndromes induced by ZNF198-FGFR1 and BCR-FGFR1 fusion genes from 8p11 translocations. Cancer Cell 2004; 5:287-98. [PMID: 15050920 DOI: 10.1016/s1535-6108(04)00053-4] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2003] [Revised: 01/20/2004] [Accepted: 02/03/2004] [Indexed: 10/26/2022]
Abstract
8p11 myeloproliferative syndrome (EMS) is a hematopoietic stem cell disorder characterized by myeloid hyperplasia and non-Hodgkin's lymphoma with chromosomal translocations fusing several genes, most commonly ZNF198, to fibroblast growth factor receptor-1 (FGFR1). However, patients with BCR-FGFR1 fusion present with typical chronic myeloid leukemia (CML). We demonstrate that ZNF198-FGFR1 induces EMS-like disease in mice, with myeloproliferation and T lymphoma arising from common multipotential progenitors. Mutation of FGFR1 Tyr766 attenuates both myeloid and lymphoid diseases, identifying phospholipase C-gamma1 as a downstream effector. Bcr-FGFR1 binds Grb2 via Bcr Tyr177 and induces CML-like leukemia in mice, whereas Bcr-FGFR1/Y177F lacks Grb2 binding and causes EMS-like disease. These results implicate different signaling pathways originating from both kinase and fusion partner in the pathogenesis of CML and EMS.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Bone Marrow/metabolism
- Carrier Proteins/metabolism
- Chromosome Breakage/genetics
- Chromosomes, Human, Pair 8/genetics
- DNA-Binding Proteins/metabolism
- GRB2 Adaptor Protein
- Humans
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism
- Lymphoma, T-Cell/metabolism
- Mice
- Myeloproliferative Disorders/metabolism
- Oncogene Proteins/metabolism
- Phospholipase C gamma
- Protein-Tyrosine Kinases
- Proteins/metabolism
- Proto-Oncogene Proteins
- Proto-Oncogene Proteins c-bcr
- Receptor Protein-Tyrosine Kinases/metabolism
- Receptor, Fibroblast Growth Factor, Type 1
- Receptors, Fibroblast Growth Factor/metabolism
- Signal Transduction
- Transcription Factors
- Translocation, Genetic/genetics
- Type C Phospholipases/metabolism
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212
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Qu X, Sada K, Kyo S, Maeno K, Miah SMS, Yamamura H. Negative regulation of FcϵRI-mediated mast cell activation by a ubiquitin-protein ligase Cbl-b. Blood 2004; 103:1779-86. [PMID: 14604964 DOI: 10.1182/blood-2003-07-2260] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
AbstractAggregation of the high-affinity immunoglobulin E (IgE) receptor (FcϵRI) on mast cells induces a number of biochemical events, including protein-tyrosine phosphorylation leading to degranulation and multiple cytokine gene transcription. Here, we have demonstrated that a second member of the Cbl family of ubiquitin-protein ligase Cbl-b translocates into the lipid raft after FcϵRI engagement. Overexpression of Cbl-b in the lipid raft inhibits FcϵRI-mediated degranulation and cytokine gene transcription through the distinct mechanism. A point mutation of Cys373 in the RING finger domain of Cbl-b abrogates the suppression of FcϵRI-mediated degranulation but not cytokine gene transcription. The antigen-induced tyrosine phosphorylation of FcϵRI, Syk, phospholipase C-γ (PLC-γ), activation of c-Jun N-terminal kinase (JNK), extracellular signal regulated kinase (ERK), inhibitor of nuclear factor κB kinase (IKK), and Ca++ influx were all suppressed in the cells overexpressing Cbl-b in the lipid raft. In particular, the expression amount of Gab2 protein and thereby its FcϵRI-mediated tyrosine phosphorylation were dramatically down-regulated by ubiquitin-protein ligase activity of Cbl-b. These results suggest that Cbl-b is a negative regulator of both Lyn-Syk-LAT and Gab2mediated complementary signaling pathways in FcϵRI-mediated mast cell activation.
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Affiliation(s)
- Xiujuan Qu
- Division of Proteomics, Department of Genome Sciences, Kobe University Graduate School of Medicine, Kobe, Japan
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213
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Tanaka A, Matsuda H. IgE crosslinkage of Fcε receptor I induces both production and activation of matrix metalloproteinase-9 in mast cells. Cell Immunol 2004; 228:66-75. [PMID: 15203321 DOI: 10.1016/j.cellimm.2004.03.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2004] [Accepted: 03/28/2004] [Indexed: 11/16/2022]
Abstract
Since mast cells play pivotal roles in allergic inflammations, we investigated how IgE-mediated stimulation modulated mast cell matrix metalloproteinase (MMP)-9 production, and its enzymatic activation. In this study, we clearly demonstrated that proMMP-9 released from murine bone marrow-derived cultured mast cells (BMCMC) was activated to its valid form after crosslinking of surface immunoglobulin (Ig)E. Serine protease inhibitors sensitive to chymases inhibited the phenomenon, indicating that certain chymases may be responsible for activation of proMMP-9. Although binding of IgE to its specific receptors did not alter MMP-9 production, the IgE crosslinkage increased both expression of mRNA, and production of MMP-9 in mast cells. Glucocorticoid declined extra cellular processing of proMMP-9 without affecting mRNA expression. These findings give rise to the possibility that production and activation of mast cell MMP-9 may be increased in the affected sites, thereby resulting in an exacerbation of tissue degradation in inflammatory conditions.
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Affiliation(s)
- Akane Tanaka
- Department of Veterinary Medicine, Laboratory of Clinical Immunology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-ch, Fuchu, Tokyo 183-8509, Japan
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214
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van den Akker E, van Dijk T, Parren-van Amelsvoort M, Grossmann KS, Schaeper U, Toney-Earley K, Waltz SE, Löwenberg B, von Lindern M. Tyrosine kinase receptor RON functions downstream of the erythropoietin receptor to induce expansion of erythroid progenitors. Blood 2004; 103:4457-65. [PMID: 14982882 DOI: 10.1182/blood-2003-08-2713] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Erythropoietin (EPO) is required for cell survival during differentiation and for progenitor expansion during stress erythropoiesis. Although signaling pathways may couple directly to docking sites on the EPO receptor (EpoR), additional docking molecules expand the signaling platform of the receptor. We studied the roles of the docking molecules Grb2-associated binder-1 (Gab1) and Gab2 in EPO-induced signal transduction and erythropoiesis. Inhibitors of phosphatidylinositide 3-kinase and Src kinases suppressed EPO-dependent phosphorylation of Gab2. In contrast, Gab1 activation depends on recruitment and phosphorylation by the tyrosine kinase receptor RON, with which it is constitutively associated. RON activation induces the phosphorylation of Gab1, mitogen-activated protein kinase (MAPK), and protein kinase B (PKB) but not of signal transducer and activator of transcription 5 (Stat5). RON activation was sufficient to replace EPO in progenitor expansion but not in differentiation. In conclusion, we elucidated a novel mechanism specifically involved in the expansion of erythroblasts involving RON as a downstream target of the EpoR.
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Affiliation(s)
- Emile van den Akker
- Department of Hematology, Erasmus MC, PO Box 1738, 3000 DR Rotterdam, the Netherlands
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215
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Stetson DB, Voehringer D, Grogan JL, Xu M, Reinhardt RL, Scheu S, Kelly BL, Locksley RM. Th2 Cells: Orchestrating Barrier Immunity. Adv Immunol 2004; 83:163-89. [PMID: 15135631 DOI: 10.1016/s0065-2776(04)83005-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Daniel B Stetson
- Howard Hughes Medical Institute, University of California San Francisco, 94143, USA
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216
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Zhu QS, Robinson LJ, Roginskaya V, Corey SJ. G-CSF-induced tyrosine phosphorylation of Gab2 is Lyn kinase dependent and associated with enhanced Akt and differentiative, not proliferative, responses. Blood 2003; 103:3305-12. [PMID: 14656892 DOI: 10.1182/blood-2003-06-1861] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The granulocyte colony-stimulating factor receptor (G-CSFR) transduces intracellular signals for myeloid cell proliferation, survival, and differentiation through the recruitment of nonreceptor protein tyrosine kinases Lyn and janus kinase 2 (Jak2). This results in the tyrosine phosphorylation of a small set of positive and negative adapters and effectors. Grb2-associated binder-2 (Gab2) is a newly described adapter molecule, preferentially expressed in hematopoietic cells and associated with phosphatidylinositol 3 (PI3) kinase. Studies suggest that Gab2 plays both positive and negative roles in cytokine receptor signaling. To investigate the role Gab2 plays in G-CSF receptor-mediated signaling, we have analyzed its activation state and correlated that with wild-type and mutant G-CSF receptors stably expressed in the murine factor-dependent Ba/F3 cell lines. G-CSF-induced tyrosine phosphorylation of Gab2 occurred in the wild-type and single Y-to-F mutants (Y704F, Y729F, and Y744F), but not in the ADA and W650R loss-of-function mutants. Cells expressing truncated proximal G-CSFR, the tyrosine-null (Y4F) G-CSFR, or Y764F mutant receptors had decreased phosphorylation of Gab2. Specific inhibitors of Src kinase (PD173 and PP1) but not Jak2 kinase (AG490) blocked Gab2 phosphorylation. Phosphorylation of Gab2 occurred in wild-type, but not Lyn-deficient, G-CSFR-transfected DT40 B cells. These data propose that Lyn, not Jak2, phosphorylates Gab2 and that maximal phosphorylation of Gab2 requires Y764, a Grb2-binding site. Serine phosphorylation of Akt, a marker of PI3-kinase activity, was detected in both wild-type and truncated proximal domain receptors, but not in the ADA and W650R mutants. Levels of phospho-Akt and phospho-extracellular signal-regulated kinase (phospho-ERK) were greater in proximal truncated than in wild-type G-CSFR cells, suggesting that Gab2 is dissociated from PI3 kinase or ERK activities. Overexpression of Gab2 enhanced the phosphorylation state of Akt, but not of ERK. This inhibited the proliferation of wild-type and truncated G-CSFR-transfected Ba/F3 cells and enhanced their myeloid differentiation. All together, these data indicate that G-CSF treatment leads to Lyn-mediated tyrosine phosphorylation of Gab2, which may serve as an important intermediate of enhanced Akt activity and myeloid differentiation, not growth/survival response.
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Affiliation(s)
- Quan-Sheng Zhu
- Division of Pediatrics, University of Texas M.D. Anderson Cancer, Houston, TX 77030, USA
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217
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Nishida K, Hirano T. The role of Gab family scaffolding adapter proteins in the signal transduction of cytokine and growth factor receptors. Cancer Sci 2003; 94:1029-33. [PMID: 14662016 PMCID: PMC11160109 DOI: 10.1111/j.1349-7006.2003.tb01396.x] [Citation(s) in RCA: 152] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2003] [Accepted: 10/20/2003] [Indexed: 11/30/2022] Open
Abstract
The Grb2-associated binder (Gab) family adapter proteins are scaffolding adapter molecules that display sequence similarity with Drosophila DOS (daughter of sevenless), which is a substrate for the protein tyrosine phosphatase Corkscrew. Gab proteins contain a pleckstrin homology (PH) domain and binding sites for SH2 and SH3 domains. A number of studies in multiple systems have implicated Gab in signaling via many different types of receptors, such as growth factor, cytokine, and antigen receptors, and via oncoproteins. Recent studies of Gab1 and Gab2 knockout mice have clearly indicated an important role for Gabs in vivo. Gab1-deficient mice die as embryos with multiple defects in placental, heart, skin, and muscle development. Gab2-deficient mice are viable, but have a defect in the mast cell lineages and in allergic reactions. Given the apparently central role played by Gab signaling via many receptors, delineating the precise mechanism(s) of Gab-mediated signaling is critical to understanding how cytokines, growth factors, and oncoproteins mediate a variety of biological activities: cell growth, differentiation, survival and malignant transformation.
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Affiliation(s)
- Keigo Nishida
- Department of Molecular Oncology (C7), Graduate School of Frontier Biosciences, Osaka University, 2-2 Yamada-oka, Suita, Osaka 565-0871
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218
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Ischenko I, Petrenko O, Gu H, Hayman MJ. Scaffolding protein Gab2 mediates fibroblast transformation by the SEA tyrosine kinase. Oncogene 2003; 22:6311-8. [PMID: 14508511 DOI: 10.1038/sj.onc.1206742] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Transformation of fibroblasts by V-SEA involves activation of the ERK and phosphatidylinositol 3-kinase (PI3K) pathways. Effector proteins that are key mediators of the ERK and PI3K pathways, namely Grb2, the tyrosine phosphatase, SHP2 and PI3K, interact with the two phosphotyrosines found in the bidentate motif in the carboxy-terminal region of V-SEA. Genetic analysis demonstrated that while Y557 was a primary binding site and thus activator of the PI3K-Akt pathway, Y564 also contributed to the activation of this pathway. Y564 was located within a Grb2-binding motif, this raised the possibility that a protein that associated with Grb2 might be important for this PI3K activation. The scaffolding proteins Gab1 and/or Gab2 were candidates for this role. In this report, we demonstrate that V-SEA preferentially interacts with Gab2. Furthermore by using Gab2 null fibroblasts, we demonstrate that Gab2 is essential for fibroblast transformation by V-SEA. Using mutant forms of Gab2, we show that activation of the PI3K-Akt pathway via Gab2 is required for V-SEA-induced transformation. However, efficient fibroblast transformation also requires the SHP2 interaction site on Gab2.
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Affiliation(s)
- Irene Ischenko
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794-5222, USA
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219
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Zhao C, Ma H, Bossy-Wetzel E, Lipton SA, Zhang Z, Feng GS. GC-GAP, a Rho family GTPase-activating protein that interacts with signaling adapters Gab1 and Gab2. J Biol Chem 2003; 278:34641-53. [PMID: 12819203 DOI: 10.1074/jbc.m304594200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Gab1 and Gab2 are scaffolding proteins acting downstream of cell surface receptors and interact with a variety of cytoplasmic signaling proteins such as Grb2, Shp-2, phosphatidylinositol 3-kinase, Shc, and Crk. To identify new binding partners for GAB proteins and better understand their functions, we performed a yeast two-hybrid screening with hGab2-(120-587) as bait. This work led to identification of a novel GTPase-activating protein (GAP) for Rho family GTPases. The GAP domain shows high similarity to the recently cloned CdGAP and displays activity toward RhoA, Rac1, and Cdc42 in vitro. The protein was named GC-GAP for its ability to interact with GAB proteins and its activity toward Rac and Cdc42. GC-GAP is predominantly expressed in the brain with low levels detected in other tissues. Antibodies directed against GC-GAP recognized a protein of approximately 200 kDa. Expression of GC-GAP in 293T cells led to a reduction in active Rac1 and Cdc42 levels but not RhoA. Suppression of GC-GAP expression by siRNA inhibited proliferation of C6 astroglioma cells. In addition, GC-GAP contains several classic proline-rich motifs, and it interacts with the first SH3 domain of Crk and full-length Nck in vitro. We propose that Gab1 and Gab2 in cooperation with other adapter molecules might regulate the cellular localization of GC-GAP under specific stimuli, acting to regulate precisely Rac and Cdc42 activities. Given that GC-GAP is specifically expressed in the nervous system and that it is localized to the dendritic processes of cultured neurons, GC-GAP may play a role in dendritic morphogenesis and also possibly in neural/glial cell proliferation.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Amino Acid Motifs
- Amino Acid Sequence
- Animals
- Blotting, Northern
- Blotting, Western
- Brain/metabolism
- Cell Differentiation
- Cell Division
- Cell Line
- DNA/metabolism
- DNA, Complementary/metabolism
- Dendrites/metabolism
- GTPase-Activating Proteins/chemistry
- GTPase-Activating Proteins/metabolism
- GTPase-Activating Proteins/physiology
- HeLa Cells
- Humans
- In Situ Hybridization
- Microscopy, Fluorescence
- Models, Genetic
- Molecular Sequence Data
- Phosphoproteins/metabolism
- Precipitin Tests
- Proline/chemistry
- Protein Binding
- Protein Structure, Tertiary
- RNA, Small Interfering/metabolism
- Sequence Homology, Amino Acid
- Signal Transduction
- Transfection
- Tumor Cells, Cultured
- Two-Hybrid System Techniques
- rac1 GTP-Binding Protein/metabolism
- rhoA GTP-Binding Protein/metabolism
- src Homology Domains
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Affiliation(s)
- Chunmei Zhao
- Burnham Institute, La Jolla, California 92037, USA
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220
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Saitoh SI, Odom S, Gomez G, Sommers CL, Young HA, Rivera J, Samelson LE. The four distal tyrosines are required for LAT-dependent signaling in FcepsilonRI-mediated mast cell activation. J Exp Med 2003; 198:831-43. [PMID: 12953098 PMCID: PMC2194190 DOI: 10.1084/jem.20030574] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2003] [Revised: 07/14/2003] [Accepted: 07/25/2003] [Indexed: 11/11/2022] Open
Abstract
The linker for activation of T cells (LAT) is an adaptor protein critical for Fc epsilon RI-mediated mast cell activation. LAT is a substrate of the tyrosine kinases activated after TCR and Fc epsilon RI engagement. After phosphorylation of the cytosolic domain of LAT, multiple signaling molecules such as phospholipase C-gamma1, Grb2, and Gads associate with phosphorylated LAT via their SH2 domains. The essential role of the four distal tyrosines in TCR-mediated signaling and T cell development has been demonstrated by experiments using LAT-deficient cell lines and genetically modified mice. To investigate the role of these four tyrosines of LAT in Fc epsilon RI-mediated mast cell activation, bone marrow-derived mast cells from LAT-deficient mice were infected with retroviral vectors designed to express wild-type or mutant LAT. Examination of bone marrow-derived mast cells expressing various tyrosine to phenylalanine mutants in LAT demonstrates a differential requirement for these different binding sites. In these studies, assays of biochemical pathways, degranulation, and cytokine and chemokine release were performed. Finally, the role of these tyrosines was also evaluated in vivo using genetically modified animals. Deletion of all four distal tyrosines, and in particular, loss of the primary phospholipase C-gamma-binding tyrosine had a significant effect on antigen-induced histamine release.
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Affiliation(s)
- Shin-ichiroh Saitoh
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
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221
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Fukao T, Terauchi Y, Kadowaki T, Koyasu S. Role of phosphoinositide 3-kinase signaling in mast cells: new insights from knockout mouse studies. J Mol Med (Berl) 2003; 81:524-35. [PMID: 12928787 DOI: 10.1007/s00109-003-0475-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2002] [Accepted: 07/10/2003] [Indexed: 01/21/2023]
Abstract
Phosphoinositide 3-kinases (PI3Ks) are a family of lipid kinases essential for diverse physiological reactions. In recent years a series of gene-targeted mice lacking different types of PI3Ks and related molecules have been generated which enable us to understand the role of PI3K pathways, particularly class I members, in vivo. Analyses of such gene-targeted mice have led to major discoveries in the physiological roles of PI3K signaling in mast cell biology. In particular the role of PI3Ks has been extensively studied in signaling through the high-affinity IgE receptor (FcepsilonRI), since mast cells are the main effector cells in type I allergic reaction associated with IgE-dependent mechanisms. Furthermore, the knockout mice have provided significant information concerning the role of PI3K signals in mast cell differentiation. This review presents several new insights into mast cell biology, which have been elucidated by the analyses of these knockout mice.
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Affiliation(s)
- Taro Fukao
- Department of Microbiology and Immunology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, 160-8582, Tokyo, Japan
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222
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Gorska MM, Alam R. Signaling molecules as therapeutic targets in allergic diseases. J Allergy Clin Immunol 2003; 112:241-50; quiz 251. [PMID: 12897726 DOI: 10.1067/mai.2003.1667] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A molecular understanding of physiologic and pathologic processes requires complete knowledge about the signal transduction mechanism of involved cells. Signal transduction research is a rapidly growing field in basic science. Unlike intercellular inflammatory mediators, signaling molecules show less functional redundancy. This allows inhibition of multiple cytokines/mediators by blocking one common signaling molecule. Interference with signaling pathways has shown significant potential for inhibition of fundamental processes as well as clinical phenotype of allergic diseases. The purpose of this review was to provide a theoretical classification of signaling molecules based on their function and to analyze various strategies for developing effective signaling inhibitors for allergic diseases.
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Affiliation(s)
- Magdalena M Gorska
- Division of Allergy and Immunology, National Jewish Medical and Research Center and University of Colorado Health Sciences Center, Denver, CO, USA
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223
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Yamamoto T, Yumioka T, Sekine Y, Sato N, Minoguchi M, Yoshimura A, Matsuda T. Regulation of FcepsilonRI-mediated signaling by an adaptor protein STAP-2/BSK in rat basophilic leukemia RBL-2H3 cells. Biochem Biophys Res Commun 2003; 306:767-73. [PMID: 12810085 DOI: 10.1016/s0006-291x(03)01042-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Crosslinking of multivalent antigen bound IgE transduces FcepsilonRI mediated signaling cascades, which activate nonreceptor-type protein-tyrosine kinases and subsequent tyrosine phosphorylation of cellular proteins, and these are critical elements for degranulation in mast cells. We cloned a novel adaptor molecule, signal transducing adaptor protein (STAP)-2 containing PH and SH2-like domains as a c-fms interacting protein. STAP-2 was identical to a recently cloned adaptor molecule, BKS, a substrate of BRK (breast tumor kinase) tyrosine kinase, although its function is still unknown. To examine a novel function of STAP-2/BSK, we expressed STAP-2/BSK or its mutants in rat basophilic leukemia RBL-2H3 cells. Overexpression of STAP-2/BSK resulted in a suppression of FcepsilonRI-mediated calcium mobilization and degranulation. FcepsilonRI-induced tyrosine phosphorylation of phospholipase C-gamma (PLC-gamma) but not Syk was significantly suppressed in these cells. Furthermore, STAP-2/BSK associated with PLC-gamma in vivo. These data indicate that STAP-2/BSK negatively controls the FcepsilonRI-mediated calcium mobilization and degranulation by direct modulation of tyrosine phosphorylation of PLC-gamma.
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Affiliation(s)
- Tetsuya Yamamoto
- Department of Immunology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-Ku Kita 12 Nishi 6, 060-0812, Sapporo, Japan
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224
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Wymann MP, Zvelebil M, Laffargue M. Phosphoinositide 3-kinase signalling--which way to target? Trends Pharmacol Sci 2003; 24:366-76. [PMID: 12871670 DOI: 10.1016/s0165-6147(03)00163-9] [Citation(s) in RCA: 304] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Matthias P Wymann
- Department of Medicine, Division of Biochemistry, University of Fribourg, Rue du Musée 5, CH-1700 Fribourg, Switzerland.
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225
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Gu H, Botelho RJ, Yu M, Grinstein S, Neel BG. Critical role for scaffolding adapter Gab2 in Fc gamma R-mediated phagocytosis. J Cell Biol 2003; 161:1151-61. [PMID: 12821647 PMCID: PMC2172986 DOI: 10.1083/jcb.200212158] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Grb2-associated binder 2 (Gab2), a member of the Dos/Gab subfamily scaffolding molecules, plays important roles in regulating the growth, differentiation, and function of many hematopoietic cell types. In this paper, we reveal a novel function of Gab2 in Fcgamma receptor (FcgammaR)-initiated phagocytosis in macrophages. Upon FcgammaR activation, Gab2 becomes tyrosyl phosphorylated and associated with p85, the regulatory subunit of phosphoinositide 3-kinase (PI3K), and the protein-tyrosine phosphatidylinositol Shp-2. FcgammaR-mediated phagocytosis is severely impaired in bone marrow-derived macrophages from Gab2-/- mice. The defect in phagocytosis correlates with decreased FcgammaR-evoked activation of Akt, a downstream target of PI3K. Using confocal fluorescence microscopy, we find that Gab2 is recruited to the nascent phagosome, where de novo PI3K lipid production occurs. Gab2 recruitment requires the pleckstrin homology domain of Gab2 and is sensitive to treatment with the PI3K inhibitor wortmannin. The Grb2 binding site on Gab2 also plays an auxiliary role in recruitment to the phagosome. Because PI3K activity is required for FcgammaR-mediated phagocytosis, our results indicate that Gab2 acts as a key component of FcgammaR-mediated phagocytosis, most likely by amplifying PI3K signaling in the nascent phagosome.
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Affiliation(s)
- Haihua Gu
- Harvard Institutes of Medicine, 77 Ave. Louis Pasteur, HIM 1047 Boston, MA 02115, USA.
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226
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Gonzalez-Espinosa C, Odom S, Olivera A, Hobson JP, Martinez MEC, Oliveira-Dos-Santos A, Barra L, Spiegel S, Penninger JM, Rivera J. Preferential signaling and induction of allergy-promoting lymphokines upon weak stimulation of the high affinity IgE receptor on mast cells. J Exp Med 2003; 197:1453-65. [PMID: 12782712 PMCID: PMC2193904 DOI: 10.1084/jem.20021806] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2002] [Revised: 03/23/2003] [Accepted: 03/23/2003] [Indexed: 11/04/2022] Open
Abstract
Mast cell degranulation and de novo cytokine production is a consequence of antigen-aggregation of the immunoglobulin E (IgE)-occupied high affinity receptor for IgE (Fc epsilon RI). Herein, we report that lymphokines that promote allergic inflammation, like MCP-1, were potently induced at low antigen (Ag) concentrations or at low receptor occupancy with IgE whereas some that down-regulate this response, like interleukin (IL)-10, required high receptor occupancy. Weak stimulation of mast cells caused minimal degranulation whereas a half-maximal secretory response was observed for chemokines and, with the exception of TNF-alpha, a weaker cytokine secretory response was observed. The medium from weakly stimulated mast cells elicited a monocyte/macrophage chemotactic response similar to that observed at high receptor occupancy. Weak stimulation also favored the phosphorylation of Gab2 and p38MAPK, while LAT and ERK2 phosphorylation was induced by a stronger stimulus. Gab2-deficient mast cells were severely impaired in chemokine mRNA induction whereas LAT-deficient mast cells showed a more pronounced defect in cytokines. These findings demonstrate that perturbation of small numbers of IgE receptors on mast cells favors certain signals that contribute to a lymphokine response that can mediate allergic inflammation.
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Affiliation(s)
- Claudia Gonzalez-Espinosa
- Molecular Inflammation Section, Molecular Immunology and Inflammation Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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227
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Seiffert M, Custodio JM, Wolf I, Harkey M, Liu Y, Blattman JN, Greenberg PD, Rohrschneider LR. Gab3-deficient mice exhibit normal development and hematopoiesis and are immunocompetent. Mol Cell Biol 2003; 23:2415-24. [PMID: 12640125 PMCID: PMC150735 DOI: 10.1128/mcb.23.7.2415-2424.2003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gab proteins are intracellular scaffolding and docking molecules involved in signaling pathways mediated by various growth factor, cytokine, or antigen receptors. Gab3 has been shown to act downstream of the macrophage colony-stimulating factor receptor, c-Fms, and to be important for macrophage differentiation. To analyze the physiological role of Gab3, we used homologous recombination to generate mice deficient in Gab3. Gab3(-/-) mice develop normally, are visually indistinguishable from their wild-type littermates, and are healthy and fertile. To obtain a detailed expression pattern of Gab3, we generated Gab3-specific monoclonal antibodies. Immunoblotting revealed a predominant expression of Gab3 in lymphocytes and bone marrow-derived macrophages. However, detailed analysis demonstrated that hematopoiesis in mice lacking Gab3 is not impaired and that macrophages develop in normal numbers and exhibit normal function. The lack of Gab3 expression during macrophage differentiation is not compensated for by increased levels of Gab1 or Gab2 mRNA. Furthermore, Gab3-deficient mice have no major immune deficiency in T- and B-lymphocyte responses to protein antigens or during viral infection. In addition, allergic responses in Gab3-deficient mice appeared to be normal. Together, these data demonstrate that loss of Gab3 does not result in detectable defects in normal mouse development, hematopoiesis, or immune system function.
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Affiliation(s)
- Martina Seiffert
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109-1024, USA
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228
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Abstract
Members of the phosphoinositide-3 kinase (PI3K) family control several cellular responses including cell growth, survival, cytoskeletal remodeling and the trafficking of intracellular organelles in many different types of cell. In particular PI3K has important functions in the immune system. It has been difficult to evaluate the roles of distinct PI3Ks in cellular immune responses because no PI3K inhibitors are specific for individual family members and because most stimuli activate several PI3K enzymes. The development of gene-targeted mice now enables us to examine the physiological functions of individual PI3K enzymes in the immune system in vivo.
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Affiliation(s)
- Shigeo Koyasu
- Department of Microbiology and Immunology, Keio University School of Medicine, Tokyo 160-8582, Japan.
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229
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Yamasaki S, Nishida K, Sakuma M, Berry D, McGlade CJ, Hirano T, Saito T. Gads/Grb2-mediated association with LAT is critical for the inhibitory function of Gab2 in T cells. Mol Cell Biol 2003; 23:2515-29. [PMID: 12640133 PMCID: PMC150736 DOI: 10.1128/mcb.23.7.2515-2529.2003] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A docking protein, Gab2, is recruited to the vicinity of the TCR complex and inhibits downstream signaling by interaction with negative regulators. However, the molecular mechanisms of this recruitment remain unclear. We have found that Gab2 associates with LAT upon TCR stimulation and that LAT is essential for Gab2 phosphorylation. By analysis of several Gab2 mutants, the c-Met binding domain (MBD) of Gab2 was found to be both necessary and sufficient for stimulation-induced LAT binding. Within the MBD domain, a novel Grb2 SH3 binding motif, PXXXR, is critical for constitutive association with Gads/Grb2. Through this association, Gab2 is recruited to the lipid raft after TCR ligation and exerts inhibitory function. The in vivo significance of this association is illustrated by the fact that T-cell responses are impaired in transgenic mice expressing wild-type Gab2 but not in mice expressing mutant Gab2 lacking the motif. Furthermore, T cells from Gab2-deficient mice showed enhanced proliferative responses upon TCR stimulation. These results indicate that Gads/Grb2-mediated LAT association is critical for the inhibitory function of Gab2, implying that Gab2 induced in stimulated T cells may exert an efficient negative feedback loop by recruiting inhibitory molecules to the lipid raft and competing with SLP-76 through Gads binding.
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Affiliation(s)
- Sho Yamasaki
- Department of Molecular Genetics, Graduate School of Medicine, Chiba University, Chuo-ku, Chiba 260-8670, Japan
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230
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Kane LP, Weiss A. The PI-3 kinase/Akt pathway and T cell activation: pleiotropic pathways downstream of PIP3. Immunol Rev 2003; 192:7-20. [PMID: 12670391 DOI: 10.1034/j.1600-065x.2003.00008.x] [Citation(s) in RCA: 210] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Ligation of the T cell receptor for antigen (TCR) and/or costimulatory receptor CD28 results in rapid activation of phosphoinositide-3 kinase (PI-3 kinase). It remains unclear, however, precisely how this activation occurs and also how the newly generated phospholipid products trigger the various events associated with T cell activation. Here we discuss the current understanding of how PI-3 kinase is activated by the TCR and CD28 and what roles its products play in T cell activation. We also review recent advances in understanding the function of Akt in particular, especially its role in CD28 costimulation. Several functional targets of Akt are discussed in this regard: inducible transcription, cell survival, glucose metabolism, and the cellular translational machinery. These pathways have been associated with TCR/CD28 costimulation, and they have also been implicated as targets of Akt.
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Affiliation(s)
- Lawrence P Kane
- Department of Medicine, The Howard Hughes Medical Institute, University of California, San Francisco, CA 94143, USA
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231
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Abstract
Tyrosine phosphorylation plays an important role in controlling cellular growth, differentiation and function. Abnormal regulation of tyrosine phosphorylation can result in human diseases such as cancer. A major challenge of signal transduction research is to determine how the initial activation of protein-tyrosine kinases (PTKs) by extracellular stimuli triggers multiple downstream signaling cascades, which ultimately elicit diverse cellular responses. Recent studies reveal that members of the Gab/Dos subfamily of scaffolding adaptor proteins (hereafter, "Gab proteins") play a crucial role in transmitting key signals that control cell growth, differentiation and function from multiple receptors. Here, we review the structure, mechanism of action and function of these interesting molecules in normal biology and disease.
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Affiliation(s)
- Haihua Gu
- Cancer Biology Program, Division of Hematology-Oncology, Dept of Medicine, Beth Israel-Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215, USA.
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232
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Lock LS, Maroun CR, Naujokas MA, Park M. Distinct recruitment and function of Gab1 and Gab2 in Met receptor-mediated epithelial morphogenesis. Mol Biol Cell 2002. [PMID: 12058075 DOI: 10.1091/mbc.02-02-0031.] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The Gab family of docking proteins (Gab1 and Gab2) are phosphorylated in response to various cytokines and growth factors. Gab1 acts to diversify the signal downstream from the Met receptor tyrosine kinase through the recruitment of multiple signaling proteins, and is essential for epithelial morphogenesis. To determine whether Gab1 and Gab2 are functionally redundant, we have examined the role of Gab2 in epithelial cells. Both Gab1 and Gab2 are expressed in epithelial cells and localize to cell-cell junctions. However, whereas overexpression of Gab1 promotes a morphogenic response, the overexpression of Gab2 fails to induce this response. We show that Gab2 recruitment to the Met receptor is dependent on the Grb2 adapter protein. In contrast, Gab1 recruitment to Met is both Grb2 dependent and Grb2 independent. The latter requires a novel amino acid sequence present in the Met-binding domain of Gab1 but not Gab2. Mutation of these residues in Gab1 impairs both association with the Met receptor and the ability of Gab1 to promote a morphogenic response, whereas their insertion into Gab2 increases Gab2 association with Met, but does not confer on Gab2 the ability to promote epithelial morphogenesis. We propose that the Grb2-independent recruitment of Gab proteins to Met is necessary but not sufficient to promote epithelial morphogenesis.
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Affiliation(s)
- Lisa S Lock
- Department of Biochemistry, Molecular Oncology Group, McGill University Health Centre, Montreal, Quebec, Canada H3A 1A1
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233
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Abstract
IgE-dependent activation of mast cells is central to the allergic response. The engagement of IgE-occupied receptors initiates a series of molecular events that cause the release of preformed, and de novo synthesis of, allergic mediators. Recent investigations demonstrate a critical role for non-enzymatic proteins that facilitate the activation and coordination of biochemical signals required for mast cell activation. Among these LAT, SLP-76 and Gab2 are critically important as adapters that facilitate events initiated by IgE receptor-dependent activation of Src family protein tyrosine kinases, Lyn and Fyn. An evaluation of the role of these adapters points to complementary but independent steps in early signaling and the possibility that preference for one or another adaptor complex may result in selective mast cell responses.
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Affiliation(s)
- Juan Rivera
- Molecular Inflammation Section, Molecular Immunology and Inflammation Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20892-1820, USA.
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234
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Maulik G, Madhiwala P, Brooks S, Ma PC, Kijima T, Tibaldi EV, Schaefer E, Parmar K, Salgia R. Activated c-Met signals through PI3K with dramatic effects on cytoskeletal functions in small cell lung cancer. J Cell Mol Med 2002; 6:539-53. [PMID: 12611639 PMCID: PMC6741298 DOI: 10.1111/j.1582-4934.2002.tb00453.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Small cell lung cancer (SCLC) is an aggressive illness with early metastases. There are several receptor tyrosine kinases (RTKs) overexpressed in SCLC, including c-Met. c-Met contains an external semaphorin-like domain, a cytoplasmic juxtamembrane domain, tyrosine kinase domain and multiple tyrosines that bind to adapter molecules. We have previously reported that c-Met is abundantly expressed in the NCI-H69 SCLC cell line and now have determined the downstream effects of stimulating c-Met via its ligand hepatocyte growth factor (HGF). Utilizing unique phospho-specific antibodies generated against various tyrosines of c-Met, we show that Y1003 (binding site for c-Cbl and a negative regulatory site), Y1313 (binding site for PI3K), Y1230/Y1234/Y1235 (autophosphorylation site), Y1349 (binding site for Grb2), Y1365 (important in cell morphogenesis) are phosphorylated in response to HGF (40 ng/ml, 7.5 min) in H69 cells. Since multiple biological and biochemical effects are transduced through the PI3K pathway, we determine the role of PI3K in the c-Met/HGF stimulation pathway. We initially determined that by inhibiting PI3K with LY294002 (50 microM over 72 hours), there was at least a 55% decrease in viability of H69 cells. Since H69 SCLC cells form clusters in cell culture, we determined the effects of HGF and LY294002 on cell motility of the clusters by time-lapse video microscopy. In response to HGF, SCLC moved much faster and formed more clusters, and this was inhibited by LY294002. Finally, we determined the downstream signal transduction of HGF stimulation of c-Met with and without inhibition of c-Met (with geldanamycin, an anisamycin antibiotic that inhibits c-Met in SCLC) or PI3K (with LY294002). We show that association of c-Met with PI3K and GAB2 is diminished by inhibiting c-Met. In summary, activation of the c-Met pathway targets the PI3K pathway in SCLC and this may be an important therapeutic target.
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Affiliation(s)
- G Maulik
- Department of Adult Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
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235
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Tavernier J, Eyckerman S, Lemmens I, Van der Heyden J, Vandekerckhove J, Van Ostade X. MAPPIT: a cytokine receptor-based two-hybrid method in mammalian cells. Clin Exp Allergy 2002; 32:1397-404. [PMID: 12372116 DOI: 10.1046/j.1365-2745.2002.01520.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Identifying novel targets for therapy in allergic disease: protein interactions inside the cell Therapy of allergic disease currently relies on pharmacological manipulation of mediators or immunotherapy. Drugs have been developed to target specific mediators and their receptors: for example antihistamines blocking the H1 receptor have been refined to maximize antagonism and reduce central side-effects or adverse effects of activity on other receptors such as muscarinic cholinergic receptors. Traditional pharmacological approaches identify new surface receptors against which chemists will then design or screen compounds for activity: examples are H3 or H4 histamine receptors. With the advent of the sequenced human genome we are faced with a vast array of genes and proteins that interact to define normal physiology or indeed pathology. A major challenge to biotechnology is to evolve novel techniques to understand the function and interaction of these myriad proteins. One particular area of current interest is the signalling cascades downstream of surface receptors. For many years pathways have appeared overlapping and to offer little chance of specific intervention. However, greater understanding of the complexity and integration of signalling, together with the possibility of directing drugs to specific cells has aroused considerable interest in this area for novel therapeutics. Indeed, targeting events within the cell has been done for many years with steroids. Here, Jan Tavernier and colleagues describe some signalling pathways relevant to allergic disease and potential methods for understanding protein interactions that allow mapping of the cascades. In particular they describe an elegant new system of analysis of protein-protein interactions in a mammalian system, which they have developed, termed MAPPIT. The basis of the system is an engineered receptor with JAK kinase but which lacks STAT activation sites. To the cytoplasmic end of the receptor is added a bait protein of interest, and the cell line can then be transduced with plasmid containing 'prey' cDNA from a library of interest linked to an active STAT binding site. If this cDNA encodes a protein which, upon expression, is activated and recruited to the membrane complex, it will bind to the receptor via the bait, then STAT activation will occur and activate a reporter gene system such as luciferase or puromycin resistance. This novel system allows study of known protein-protein interactions by targeted mutagenesis, or screening for novel interactions. It has the advantage over existing systems such as yeast 2 hybrid that it uses mammalian cells and thus can reproduce the physiological conditions for protein processing or activation. As new genes and proteins are linked to the atopic phenotypes, systems such as this hold promise of rapidly defining their function and interacting proteins and may be important in linking genomics and proteomics with function and pharmacology in the future.
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Affiliation(s)
- J Tavernier
- VIB09 Department of Medical Protein Research, Faculty of Medicine and Health Sciences, Department of Biochemistry, Ghent University, Ghent Belgium.
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236
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Kawakami T, Galli SJ. Regulation of mast-cell and basophil function and survival by IgE. Nat Rev Immunol 2002; 2:773-86. [PMID: 12360215 DOI: 10.1038/nri914] [Citation(s) in RCA: 434] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mast cells and basophils are important effector cells in T helper 2 (T(H)2)-cell-dependent, immunoglobulin-E-associated allergic disorders and immune responses to parasites. The crosslinking of IgE that is bound to the high-affinity receptor Fc epsilon RI with multivalent antigen results in the aggregation of Fc epsilon RI and the secretion of products that can have effector, immunoregulatory or autocrine effects. This response can be enhanced markedly in cells that have been exposed to high levels of IgE, which results in the increased surface expression of Fc epsilon RI. Moreover, recent work indicates that monomeric IgE (in the absence of crosslinking) can render mast cells resistant to apoptosis induced by growth-factor deprivation in vitro and, under certain circumstances, can induce the release of cytokines. So, the binding of IgE to Fc epsilon RI might influence mast-cell and basophil survival directly or indirectly, and can also regulate cellular function.
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Affiliation(s)
- Toshiaki Kawakami
- Division of Allergy, La Jolla Institute for Allergy and Immunology, 10355 Science Center Drive, San Diego, California 92121, USA
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237
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Sada K, Miah SMS, Maeno K, Kyo S, Qu X, Yamamura H. Regulation of FcepsilonRI-mediated degranulation by an adaptor protein 3BP2 in rat basophilic leukemia RBL-2H3 cells. Blood 2002; 100:2138-44. [PMID: 12200378 DOI: 10.1182/blood-2001-12-0340] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aggregation of high-affinity IgE receptor FcepsilonRI induces sequential activation of nonreceptor-type protein-tyrosine kinases and subsequent tyrosine phosphorylation of cellular proteins, leading to degranulation in mast cells. A hematopoietic cell-specific adaptor protein, 3BP2, that was originally identified as an Abl SH3-binding protein was rapidly tyrosine phosphorylated by the aggregation of FcepsilonRI on rat basophilic leukemia RBL-2H3 cells. Tyrosine phosphorylation of 3BP2 did not depend on calcium influx from external sources. To examine the role of 3BP2 in mast cells, we overexpressed the SH2 domain of 3BP2 in the RBL-2H3 cells. Overexpression of 3BP2-SH2 domain resulted in a suppression of antigen-induced degranulation as assessed by beta-hexosaminidase release. Even though overall tyrosine phosphorylation of cellular protein was not altered, antigen-mediated tyrosine phosphorylation of phospholipase C-gamma (PLC-gamma) and calcium mobilization were significantly suppressed in the cells overexpressing the 3BP2-SH2 domain. Furthermore, antigen stimulation induced the association of 3BP2-SH2 domain with LAT and other signaling molecule complexes in the RBL-2H3 cells. FcepsilonRI-mediated phosphorylation of JNK and ERK was not affected by the overexpression of 3BP2-SH2 domain. These data indicate that 3BP2 functions to positively regulate the FcepsilonRI-mediated tyrosine phosphorylation of PLC-gamma and thereby the signals leading to degranulation.
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Affiliation(s)
- Kiyonao Sada
- Division of Proteomics, Department of Genome Sciences, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
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238
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Suzuki-Nishimura T, Uchida MK. Prostaglandin D2 generation by rat peritoneal mast cells stimulated with Datura stramonium agglutinin and its inhibition by haptenic sugar and wheat germ agglutinin. JAPANESE JOURNAL OF PHARMACOLOGY 2002; 90:77-80. [PMID: 12396030 DOI: 10.1254/jjp.90.77] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The production of prostaglandin D2 (PGD2) by rat peritoneal mast cells incubated with N-acetyl glucosamine (GlcNAc) oligomer-specific Datura stramonium agglutinin (DSA) for 10 min in the presence of 0.3 mM Ca2+ was examined. Previously, our group reported that the incubation of rat mast cells with DSA (5 - 100 microg/ml) under similar conditions resulted in a calcium influx and histamine release via a pertussis toxin-sensitive G-protein pathway of the mast cells, and the histamine release was inhibited by haptenic sugar chitooligosaccharides or GlcNAc-specific lectin wheat germ agglutinin (WGA) (K. Matsuda et al., Jpn J Pharmacol 66, 195 - 204 (1994)). DSA (5 - 100 microg/ml) dose-dependently stimulated the mast cells to generate PGD2. Chitooligosaccharides (1% w/v) and WGA (100 microg/ml) inhibited the production of PGD2 induced by 100 microg/ml of DSA, suggesting that the effect of DSA is sugar-specific. A prostaglandin G/H synthase inhibitor NS-398 (N-[cyclohexyloxy-4-nitrophenyl] methanesulfonamide) (10 microM) inhibited the formation of PGD2 induced by DSA (20 microg/ml). These results suggest that the binding of DSA to the corresponding sugar residues on the mast cell surface mediates the signaling of the prostaglandin G/H synthase pathway.
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239
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Rivera J, Cordero JR, Furumoto Y, Luciano-Montalvo C, Gonzalez-Espinosa C, Kovarova M, Odom S, Parravicini V. Macromolecular protein signaling complexes and mast cell responses: a view of the organization of IgE-dependent mast cell signaling. Mol Immunol 2002; 38:1253-8. [PMID: 12217392 DOI: 10.1016/s0161-5890(02)00072-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The generation of signals following engagement of cell surface receptors is an ordered process that requires tight regulation as spurious signals could result in unwanted, and possibly deleterious, cellular responses. Like other cell surface receptors, stimulation of a mast cell via the high affinity IgE receptor (FcepsilonRI) causes multiple biochemical events that ultimately result in cell activation and effector responses. Recently, our knowledge of how these events are ordered has increased. We now have identified some of the molecules involved, how they are organized into macromolecular complexes by FcepsilonRI stimulation, and the role of some of the constituents of these macromolecular signaling complexes in mast cell effector responses. In brief, we review the knowledge on macromolecular signaling complexes used by FcepsilonRI in mast cell activation and provide our view on the regulation of signal generation and its effect on mast cell activation.
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Affiliation(s)
- Juan Rivera
- Molecular Inflammation Section, Molecular Immunology and Inflammation Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institute of Health (NIH), Bethesda, MD 20892-1820, USA.
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240
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Daly RJ, Gu H, Parmar J, Malaney S, Lyons RJ, Kairouz R, Head DR, Henshall SM, Neel BG, Sutherland RL. The docking protein Gab2 is overexpressed and estrogen regulated in human breast cancer. Oncogene 2002; 21:5175-81. [PMID: 12140767 DOI: 10.1038/sj.onc.1205522] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2002] [Revised: 03/18/2002] [Accepted: 03/26/2002] [Indexed: 11/09/2022]
Abstract
Grb2-associated binder 2 (Gab2) is a recently identified member of the Gab/Daughter of sevenless family of docking proteins, which localize, amplify and integrate signaling pathways activated by various receptors including receptor tyrosine kinases (RTKs). To date, Gab2 signaling has been primarily investigated in hematopoietic cells. Here we report marked overexpression of Gab2 in a subset of breast cancer cell lines relative to normal breast epithelial strains and a trend for increased Gab2 expression in estrogen receptor (ER)-positive lines. Overexpression relative to normal ductal epithelium was also observed in some primary breast cancers. In MCF-7 breast cancer cells Gab2 was markedly tyrosine phosphorylated in response to heregulin and also following EGF, insulin or bFGF administration, indicating that a variety of RTKs implicated in breast cancer development or progression couple to this docking protein. In hormone-responsive breast cancer cells, GAB2 mRNA and protein expression were induced by estradiol in a manner sensitive to the pure anti-estrogen ICI 182780, indicating that this regulation is mediated via the ER. Gab2 therefore represents a novel link between steroid and growth factor signaling in breast cancer, and when overexpressed, may modulate the sensitivity of breast cancer cells to these important growth regulators.
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Affiliation(s)
- Roger J Daly
- Cancer Research Program, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, NSW 2010, Australia.
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241
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Parravicini V, Gadina M, Kovarova M, Odom S, Gonzalez-Espinosa C, Furumoto Y, Saitoh S, Samelson LE, O'Shea JJ, Rivera J. Fyn kinase initiates complementary signals required for IgE-dependent mast cell degranulation. Nat Immunol 2002; 3:741-8. [PMID: 12089510 DOI: 10.1038/ni817] [Citation(s) in RCA: 362] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Fc epsilon RI activation of mast cells is thought to involve Lyn and Syk kinases proximal to the receptor and the signaling complex organized by the linker for activation of T cells (LAT). We report here that Fc epsilon RI also uses a Fyn kinase-dependent pathway that does not require Lyn kinase or the adapter LAT for its initiation, but is necessary for mast cell degranulation. Lyn-deficiency enhanced Fyn-dependent signals and degranulation, but inhibited the calcium response. Fyn-deficiency impaired degranulation, whereas Lyn-mediated signaling and calcium was normal. Thus, Fc epsilon RI-dependent mast cell degranulation involves cross-talk between Fyn and Lyn kinases.
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Affiliation(s)
- Valentino Parravicini
- Molecular Inflammation Section, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892-1820, USA
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242
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Heneberg P, Dráber P. Nonreceptor protein tyrosine and lipid phosphatases in type I fc(epsilon) receptor-mediated activation of mast cells and basophils. Int Arch Allergy Immunol 2002; 128:253-63. [PMID: 12218363 DOI: 10.1159/000063864] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Protein tyrosine and lipid phosphorylations are early and critical events in type 1 Fc(epsilon) receptor (Fc(epsilon)RI)-mediated activation of mast cells and basophils. Tyrosine phosphorylation of Fc(epsilon)RI subunits as well as other signal transduction molecules reflects the balance between the action of protein tyrosine kinases and phosphatases. Similarly, the phosphate content of inositol phospholipids, involved in the recruitment of signalling molecules to the plasma membrane and the generation of secondary messengers, is the net result of the opposing effects of phosphoinositide kinases and lipid phosphatases. This review summarizes the current understanding of the structural and functional aspects of nonreceptor protein tyrosine phosphatases (SHP-1, SHP-2, HePTP, PTP20, PRL1, PRL2, PTP-MEG1 and PTP-MEG2) and lipid phosphatases (SHIP and SHIP2) in the activation of mast cells and basophils after Fc(epsilon)RI aggregation. New approaches towards a deeper understanding of the role of phosphatases in mast cell physiology are also discussed.
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Affiliation(s)
- Petr Heneberg
- Institute of Molecular Genetics, Academy of Science of the Czech Republic, Prague, Czech Republic
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244
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Wong MX, Roberts D, Bartley PA, Jackson DE. Absence of platelet endothelial cell adhesion molecule-1 (CD31) leads to increased severity of local and systemic IgE-mediated anaphylaxis and modulation of mast cell activation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:6455-62. [PMID: 12055265 DOI: 10.4049/jimmunol.168.12.6455] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Platelet endothelial cell adhesion molecule-1 (PECAM-1) is a newly assigned member of the Ig-immunoreceptor tyrosine-based inhibitory motif superfamily, and its functional role is suggested to be an inhibitory receptor that modulates immunoreceptor tyrosine-based activation motif-dependent signaling cascades. In this study, we hypothesized that PECAM-1 plays an essential in vivo role as a counterregulator of immediate hypersensitivity reactions. We found that PECAM-1 was highly expressed on the surface of immature bone marrow mast cells and at a lower density on mature peritoneal mast cells. Examination of skin biopsies from PECAM-1(+/+) and PECAM-1(-/-) mice revealed that absence of PECAM-1 did not affect mast cell development or the capacity of mast cells to populate tissues. To examine whether the absence of PECAM-1 would influence immediate hypersensitivity reactions, PECAM-1(+/+) and PECAM-1(-/-) mice were presensitized with anti-DNP mouse IgE and then challenged 20 h later with DNP-BSA or PBS. PECAM-1(-/-) mice exhibited elevated serum histamine concentrations after Ag stimulation compared with PECAM-1(+/+) mice, indicating an increased severity of systemic IgE-mediated anaphylaxis. PECAM-1(-/-) mice have increased sensitivity to local cutaneous IgE-dependent anaphylaxis compared with PECAM-1(+/+) mice, as assessed by greater tissue swelling of their ears and mast cell degranulation in situ. PECAM-1(-/-) bone marrow mast cells showed enhanced dense granule serotonin release after Fc epsilon RI cross-linking in vitro. These results suggest that PECAM-1 acts as a counterregulator in allergic disease susceptibility and severity and negatively modulates mast cell activation.
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Affiliation(s)
- Mae-Xhum Wong
- Division of Hematology, Hanson Institute, Institute of Medical and Veterinary Science, Adelaide, South Australia, Australia
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245
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Lock LS, Maroun CR, Naujokas MA, Park M. Distinct recruitment and function of Gab1 and Gab2 in Met receptor-mediated epithelial morphogenesis. Mol Biol Cell 2002; 13:2132-46. [PMID: 12058075 PMCID: PMC117630 DOI: 10.1091/mbc.02-02-0031] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The Gab family of docking proteins (Gab1 and Gab2) are phosphorylated in response to various cytokines and growth factors. Gab1 acts to diversify the signal downstream from the Met receptor tyrosine kinase through the recruitment of multiple signaling proteins, and is essential for epithelial morphogenesis. To determine whether Gab1 and Gab2 are functionally redundant, we have examined the role of Gab2 in epithelial cells. Both Gab1 and Gab2 are expressed in epithelial cells and localize to cell-cell junctions. However, whereas overexpression of Gab1 promotes a morphogenic response, the overexpression of Gab2 fails to induce this response. We show that Gab2 recruitment to the Met receptor is dependent on the Grb2 adapter protein. In contrast, Gab1 recruitment to Met is both Grb2 dependent and Grb2 independent. The latter requires a novel amino acid sequence present in the Met-binding domain of Gab1 but not Gab2. Mutation of these residues in Gab1 impairs both association with the Met receptor and the ability of Gab1 to promote a morphogenic response, whereas their insertion into Gab2 increases Gab2 association with Met, but does not confer on Gab2 the ability to promote epithelial morphogenesis. We propose that the Grb2-independent recruitment of Gab proteins to Met is necessary but not sufficient to promote epithelial morphogenesis.
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Affiliation(s)
- Lisa S Lock
- Department of Biochemistry, Molecular Oncology Group, McGill University Health Centre, Montreal, Quebec, Canada H3A 1A1
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246
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Plas DR, Rathmell JC, Thompson CB. Homeostatic control of lymphocyte survival: potential origins and implications. Nat Immunol 2002; 3:515-21. [PMID: 12032565 DOI: 10.1038/ni0602-515] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Lymphocytes depend on extracellular ligands to maintain their viability. Structurally diverse lymphocyte receptors transmit survival signals through separate signal transduction cascades, which all share the ability to sustain viability by maintaining the sequestration of apoptogenic factors within mitochondria. Receptors can induce cellular survival either by promoting the expression and/or function of anti-apoptotic Bcl-2 family proteins or by activating the phosphatidylinositol-3 kinase Akt pathway. Either of these events represses the function of the pro-apoptotic proteins Bax and Bak, which are required for mitochondrial release of cytochrome c. As we discuss here, the apparently redundant functions of Bax and Bak may have evolved to prevent lymphocyte mitochondria from adapting to loss of receptor mediated signal transduction and thus keep lymphocytes from accumulating in a cell-autonomous manner.
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Affiliation(s)
- David R Plas
- Abramson Family Cancer Research Institute and Department of Cancer Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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247
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Leitges M, Gimborn K, Elis W, Kalesnikoff J, Hughes MR, Krystal G, Huber M. Protein kinase C-delta is a negative regulator of antigen-induced mast cell degranulation. Mol Cell Biol 2002; 22:3970-80. [PMID: 12024011 PMCID: PMC133855 DOI: 10.1128/mcb.22.12.3970-3980.2002] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Regulation of mast cell degranulation is dependent on the subtle interplay of cellular signaling proteins. The Src homology 2 (SH2) domain-containing inositol-5'-phosphatase (SHIP), which acts as the gatekeeper of degranulation, binds via both its SH2 domain and its phosphorylated NPXY motifs to the adapter protein Shc via the latter's phosphorylated tyrosines and phosphotyrosine-binding domain, respectively. This theoretically leaves Shc's SH2 domain available to bind proteins, which might be part of the SHIP/Shc complex. In a search for such proteins, protein kinase C-delta (PKC-delta) was found to coprecipitate in mast cells with Shc and to interact with Shc's SH2 domain following antigen or pervanadate stimulation. Phosphorylation of PKC-delta's Y(332), most likely by Lyn, was found to be responsible for PKC-delta's binding to Shc's SH2 domain. Using PKC-delta(-/-) bone marrow-derived mast cells (BMMCs), we found that the antigen-induced tyrosine phosphorylation of Shc was similar to that in wild-type (WT) BMMCs while that of SHIP was significantly increased. Moreover, increased translocation of PKC-delta to the membrane, as well as phosphorylation at T505, was observed in SHIP(-/-) BMMCs, demonstrating that while PKC-delta regulates SHIP phosphorylation, SHIP regulates PKC-delta localization and activation. Interestingly, stimulation of PKC-delta(-/-) BMMCs with suboptimal doses of antigen yielded a more sustained calcium mobilization and a significantly higher level of degranulation than that of WT cells. Altogether, our data suggest that PKC-delta is a negative regulator of antigen-induced mast cell degranulation.
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Affiliation(s)
- Michael Leitges
- Max Planck Institute for Experimental Endocrinology, 30625 Hannover, Germany
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248
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Abstract
Recent results obtained in mice harboring cytoplasmic mutations of Igalpha and/or Igbeta have reinforced the concept that the strength of BCR signaling is important for ensuring appropriate developmental outcomes as well as antigen-specific responses. To establish the optimal signaling intensity and duration, the BCR utilizes positive and negative regulatory molecules. Studies are beginning to reveal how these molecules maintain immunological homeostasis and tolerance.
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Affiliation(s)
- Tomohiro Kurosaki
- Department of Molecular Genetics, Institute for Liver Research, Kansai Medical University, and Laboratory for Lymphocyte Differentiation, RIKEN Research Center for Allergy and Immunology, 570-8506, Moriguchi, Japan.
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Sattler M, Mohi MG, Pride YB, Quinnan LR, Malouf NA, Podar K, Gesbert F, Iwasaki H, Li S, Van Etten RA, Gu H, Griffin JD, Neel BG. Critical role for Gab2 in transformation by BCR/ABL. Cancer Cell 2002; 1:479-92. [PMID: 12124177 DOI: 10.1016/s1535-6108(02)00074-0] [Citation(s) in RCA: 293] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The BCR/ABL oncogene causes chronic myelogenous leukemia (CML) in humans and a CML-like disease, as well as lymphoid leukemia, in mice. p210 BCR/ABL is an activated tyrosine kinase that phosphorylates itself and several cellular signaling proteins. The autophosphorylation site tyrosine 177 binds the adaptor Grb2 and helps determine the lineage and severity of BCR/ABL disease: Tyr177 mutation (BCR/ABL-Y177F) dramatically impairs myeloid leukemogenesis, while diminishing lymphoid leukemogenesis. The critical signal(s) from Tyr177 has remained unclear. We report that Tyr177 recruits the scaffolding adaptor Gab2 via a Grb2/Gab2 complex. Compared to BCR/ABL-expressing Ba/F3 cells, BCR/ABL-Y177F cells exhibit markedly reduced Gab2 tyrosine phosphorylation and association of phosphatidylinositol-3 kinase (PI3K) and Shp2 with Gab2 and BCR/ABL, and decreased PI3K/Akt and Ras/Erk activation, cell proliferation, and spontaneous migration. Remarkably, bone marrow myeloid progenitors from Gab2 (-/-) mice are resistant to transformation by BCR/ABL, whereas lymphoid transformation is diminished as a consequence of markedly increased apoptosis. BCR/ABL-evoked PI3K/Akt and Ras/Erk activation also are impaired in Gab2 (-/-) primary myeloid and lymphoid cells. Our results identify Gab2 and its associated proteins as key determinants of the lineage and severity of BCR/ABL transformation.
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Affiliation(s)
- Martin Sattler
- Dana-Farber Cancer Institute, Department of Adult Oncology, Harvard Medical School, 44 Binney Street, Boston, Massachusetts 02115, USA
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Xie ZH, Ambudkar I, Siraganian RP. The adapter molecule Gab2 regulates Fc epsilon RI-mediated signal transduction in mast cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:4682-91. [PMID: 11971018 DOI: 10.4049/jimmunol.168.9.4682] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The recently cloned scaffolding molecule Gab2 can assemble multiple molecules involved in signaling pathways. Bone marrow-derived mast cells isolated from Gab2(-/-) mice have defective signaling probably due to the lack of the activation of phosphatidylinositol-3 kinase (PI3-kinase). In this study, we investigated the role of Gab2 using the rat basophilic leukemia 2H3 cell line mast cells. Fc epsilon RI aggregation induced the tyrosine phosphorylation of Gab2 and translocation of a significant fraction of it from the cytosol to the plasma membrane. As in other cells, Gab2 was found to associate with several signaling molecules including Src homology 2-containing protein tyrosine phosphatase 2, Grb2, Lyn, and phospholipase C gamma (PLC gamma). The association of Gab2 with Lyn and PLC gamma were enhanced after receptor aggregation. Overexpression of Gab2 in rat basophilic leukemia 2H3 cell line cells inhibited the Fc epsilon RI-induced tyrosine phosphorylation of the subunits of the receptor, and the phosphorylation and/or activation of Syk and mitogen-activated protein kinase. Downstream events such as calcium mobilization, degranulation, and induction of TNF-alpha and IL-6 gene transcripts were decreased in Gab2 overexpressing cells, although Akt phosphorylation as a measure of PI3-kinase activation was unaffected. These results suggest that in addition to the positive effects mediated by PI3-kinase that are apparent in Gab2(-/-) mast cells, Gab2 by interacting with Lyn and PLC gamma may have negative regulatory effects on Fc epsilon RI-induced mast cell signaling and functions.
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Affiliation(s)
- Zhi-Hui Xie
- Receptors and Signal Transduction Section, Oral Infection and Immunity Branch, Department of Health and Human Services, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
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