351
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Hernandez-Hansen V, Mackay GA, Lowell CA, Wilson BS, Oliver JM. The Src kinase Lyn is a negative regulator of mast cell proliferation. J Leukoc Biol 2003; 75:143-51. [PMID: 14525964 DOI: 10.1189/jlb.0503224] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Previous investigators have reported that deletion of the protein tyrosine kinase Lyn alters mast cell (MC) signaling responses but does not affect or reduces the cytokine-mediated proliferation of mouse bone marrow-derived MC (BMMC) precursors and of mature MC. We observed that Lyn-deficient mice have more peritoneal MC than wild-type (WT) mice. Studies to explore this unexpected result showed that Lyn(-/-) BM cells expand faster than WT cells in response to interleukin (IL)-3 and stem-cell factor over the 4-5 weeks required to produce a >95% pure population of granular, receptor with high affinity for immunoglobulin E-positive BMMC. Furthermore, differentiated Lyn(-/-) BMMC continue to proliferate more rapidly than WT BMMC and undergo less apoptosis in response to cytokine withdrawal. Additionally, Lyn(-/-) BMMC support greater IL-3-mediated phosphorylation of the prosurvival kinase, Akt, and the proliferative kinase, extracellular-regulated kinase 1/2. These results identify Lyn as a negative regulator of murine MC survival and proliferation.
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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 Rm. 205, 2325 Camino De Salud NE, Albuquerque, NM 87131, USA.
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352
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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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353
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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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354
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Pombo I, Rivera J, Blank U. Munc18-2/syntaxin3 complexes are spatially separated from syntaxin3-containing SNARE complexes. FEBS Lett 2003; 550:144-8. [PMID: 12935901 DOI: 10.1016/s0014-5793(03)00864-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Exocytosis of mast cell granules requires a vesicular- and plasma membrane-associated fusion machinery. We examined the distribution of SNARE membrane fusion and Munc18 accessory proteins in lipid rafts of RBL mast cells. SNAREs were found either excluded (syntaxin2), equally distributed between raft and non-raft fractions (syntaxin4, VAMP-8, VAMP-2), or selectively enriched in rafts (syntaxin3, SNAP-23). Syntaxin4-binding Munc18-3 was absent, whereas small amounts of the syntaxin3-interacting partner Munc18-2 consistently distributed into rafts. Cognate SNARE complexes of syntaxin3 with SNAP-23 and VAMP-8 were enriched in rafts, whereas Munc18-2/syntaxin3 complexes were excluded. This demonstrates a spatial separation between these two types of complexes and suggests that Munc18-2 acts in a step different from SNARE complex formation and fusion.
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Affiliation(s)
- Isabel Pombo
- Unité d'Immuno-Allergie, Institut Pasteur, Paris, France
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355
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Lam V, Kalesnikoff J, Lee CWK, Hernandez-Hansen V, Wilson BS, Oliver JM, Krystal G. IgE alone stimulates mast cell adhesion to fibronectin via pathways similar to those used by IgE + antigen but distinct from those used by Steel factor. Blood 2003; 102:1405-13. [PMID: 12702510 DOI: 10.1182/blood-2002-10-3176] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We recently demonstrated that immunoglobulin E (IgE), in the absence of cross-linking agents, activates signaling pathways in healthy murine bone marrow-derived mast cells (BMMCs) and that this activation enhances BMMC survival, at least in part, via secretion of autocrine-acting cytokines. We report herein that IgE alone also triggers the adhesion of both BMMCs and connective tissue mast cells (CTMCs) to the connective tissue component, fibronectin (FN). This adhesion occurs to the same extent as that triggered by optimal levels of Steel factor (SF) or IgE + antigen (IgE + Ag) and is mediated by an increased avidity of the integrin very late antigen 5 (VLA-5). Moreover, this IgE-induced adhesion, which is prolonged compared with that elicited by SF or IgE + Ag, requires phosphatidylinositol 3-kinase (PI3K), phospholipase C gamma (PLCgamma), and extracellular calcium but not extracellular-regulated kinase (Erk) or p38. Interestingly, we found, using the calcium channel blocker, 2-APB (2-aminoethoxydiphenyl borate) and Lyn-/- BMMCs that both IgE- and IgE + Ag-induced adhesion to FN require extracellular calcium entry, whereas SF does not. Furthermore, our data suggest that FN acts synergistically with IgE to prolong intracellular phosphorylation events and to enhance IgE-induced inflammatory cytokine production and BMMC survival.
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Affiliation(s)
- Vivian Lam
- Terry Fox Laboratory, BC Cancer Agency, Vancouver, BC, Canada
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356
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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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357
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Young RM, Holowka D, Baird B. A lipid raft environment enhances Lyn kinase activity by protecting the active site tyrosine from dephosphorylation. J Biol Chem 2003; 278:20746-52. [PMID: 12670955 DOI: 10.1074/jbc.m211402200] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The plasma membrane contains ordered lipid domains, commonly called lipid rafts, enriched in cholesterol, sphingolipids, and certain signaling proteins. Lipid rafts play a structural role in signal initiation by the high affinity receptor for IgE. Cross-linking of IgE-receptor complexes by antigen causes their coalescence with lipid rafts, where they are phosphorylated by the Src family tyrosine kinase, Lyn. To understand how lipid rafts participate in functional coupling between Lyn and FcepsilonRI, we investigated whether the lipid raft environment influences the specific activity of Lyn. We used differential detergent solubility and sucrose gradient fractionation to isolate Lyn from raft and nonraft regions of the plasma membrane in the presence or absence of tyrosine phosphatase inhibitors. We show that Lyn recovered from lipid rafts has a substantially higher specific activity than Lyn from nonraft environments. Furthermore, this higher specific activity correlates with increased tyrosine phosphorylation at the active site loop of the kinase domain. Based on these results, we propose that lipid rafts exclude a phosphatase that negatively regulates Lyn kinase activity by constitutive dephosphorylation of the kinase domain tyrosine residue of Lyn. In this model, cross-linking of FcepsilonRI promotes its proximity to active Lyn in a lipid raft environment.
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Affiliation(s)
- Ryan M Young
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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358
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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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359
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Fujii Y, Wakahara S, Nakao T, Hara T, Ohtake H, Komurasaki T, Kitamura K, Tatsuno A, Fujiwara N, Hozumi N, Ra C, Kitamura D, Goitsuka R. Targeting of MIST to Src-family kinases via SKAP55-SLAP-130 adaptor complex in mast cells. FEBS Lett 2003; 540:111-6. [PMID: 12681493 DOI: 10.1016/s0014-5793(03)00234-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
MIST (mast cell immunoreceptor signal transducer; also termed Clnk) is an adaptor protein structurally related to SLP-76-family hematopoietic cell-specific adaptor proteins. We demonstrate here that two major MIST-associated phosphoproteins expressed in mast cell lines are SLAP-130 and SKAP55, adaptors known to interact with the Src-homology (SH) 2 domain of Src-family protein tyrosine kinases (PTKs). MIST directly associated with SLAP-130 via its SH2 domain, and collaboration of SLAP-130 with SKAP55 was required for the recruitment of MIST to Lyn. Furthermore, MIST was preferentially recruited to Fyn rather than Lyn, which is regulated by higher affinity binding of SLAP-130 and SKAP55 with the Fyn-SH2 domain than the Lyn-SH2 domain. Our results suggest that the MIST-SLAP-130-SKAP55 adaptor complex functions downstream of high-affinity IgE receptor-associated Src-PTKs in mast cells.
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Affiliation(s)
- Yasuyuki Fujii
- Department of Molecular Biology Laboratory, Medicinal Research Laboratories, Taisho Pharmaceutical Co Ltd, 1-403 Yoshino-cho, Saitama-shi, Saitama 330-8530, Japan
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360
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Faeder JR, Hlavacek WS, Reischl I, Blinov ML, Metzger H, Redondo A, Wofsy C, Goldstein B. Investigation of early events in Fc epsilon RI-mediated signaling using a detailed mathematical model. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:3769-81. [PMID: 12646643 DOI: 10.4049/jimmunol.170.7.3769] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Aggregation of Fc epsilon RI on mast cells and basophils leads to autophosphorylation and increased activity of the cytosolic protein tyrosine kinase Syk. We investigated the roles of the Src kinase Lyn, the immunoreceptor tyrosine-based activation motifs (ITAMs) on the beta and gamma subunits of Fc epsilon RI, and Syk itself in the activation of Syk. Our approach was to build a detailed mathematical model of reactions involving Fc epsilon RI, Lyn, Syk, and a bivalent ligand that aggregates Fc(epsilon)RI. We applied the model to experiments in which covalently cross-linked IgE dimers stimulate rat basophilic leukemia cells. The model makes it possible to test the consistency of mechanistic assumptions with data that alone provide limited mechanistic insight. For example, the model helps sort out mechanisms that jointly control dephosphorylation of receptor subunits. In addition, interpreted in the context of the model, experimentally observed differences between the beta- and gamma-chains with respect to levels of phosphorylation and rates of dephosphorylation indicate that most cellular Syk, but only a small fraction of Lyn, is available to interact with receptors. We also show that although the beta ITAM acts to amplify signaling in experimental systems where its role has been investigated, there are conditions under which the beta ITAM will act as an inhibitor.
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Affiliation(s)
- James R Faeder
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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361
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Abstract
X-linked lymphoproliferative (XLP) disease is a human immune dysfunction characterized primarily by an inappropriate response to Epstein-Barr virus infection. In 1998, it was discovered that XLP is caused by inactivating mutations in the SAP/SH2D1A/DSHP gene. This gene codes for an immune cell-specific polypeptide termed SAP (SLAM-associated protein) that is composed almost exclusively of an Src homology 2 (SH2) domain. By way of its SH2 domain, SAP interacts with tyrosine-based motifs located in the cytoplasmic region of members of the SLAM (signaling lymphocyte activation molecule) family of receptors. Recent findings indicate that SAP is required for the function of SLAM-related receptors, as a consequence of its capacity to promote the recruitment and activation of the Src-related protein tyrosine kinase FynT, thereby allowing SLAM receptor-mediated protein tyrosine phosphorylation signals in immune cells. Functional and genetic analyses suggest that the phenotype associated with XLP is caused in large part by defects in the functions of SLAM-related receptors due to SAP deficiency.
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Affiliation(s)
- Sylvain Latour
- Unité INSERM U429, Hôpital Necker Enfants-Malades, Paris, France.
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362
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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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363
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Zamoyska R, Basson A, Filby A, Legname G, Lovatt M, Seddon B. The influence of the src-family kinases, Lck and Fyn, on T cell differentiation, survival and activation. Immunol Rev 2003; 191:107-18. [PMID: 12614355 DOI: 10.1034/j.1600-065x.2003.00015.x] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The src-family kinases p56lck (Lck) and p59fyn (Fyn) are expressed in T cells and are among the first signaling molecules to be activated downstream of the T cell receptor (TCR). Evidence is emerging that although closely related, these signaling molecules have discrete functions during development, maintenance and activation of peripheral T cells. For example, during thymopoiesis Lck is uniquely able to provide all the signals required for pre-TCRbeta selection, although Fyn can substitute for a subset of these. Positive selection of CD4 single-positive (SP) cells is also critically dependent on the expression of Lck but not Fyn, while differentiation of CD8 SP cells proceeds relatively efficiently in the absence of Lck. In naïve peripheral T cells either Lck or Fyn can transmit TCR-mediated survival signals, and yet only Lck is able to trigger TCR-mediated expansion signals under conditions of lymphopenia. Stimulation of naïve T cells by antigenic stimuli is also severely compromised in the absence of Lck, but more subtly impaired by the absence of Fyn. We discuss recent experiments addressing how these two src-kinase family members interface with downstream signaling pathways to regulate these diverse aspects of T cell behavior.
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Affiliation(s)
- Rose Zamoyska
- Division of Molecular Immunology, National Institute for Medical Research, London, UK.
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364
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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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365
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