201
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Eisenbraun MD, Tamir A, Miller RA. Altered composition of the immunological synapse in an anergic, age-dependent memory T cell subset. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:6105-12. [PMID: 10843659 DOI: 10.4049/jimmunol.164.12.6105] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In young mice, memory CD4 T lymphocytes with high P-glycoprotein activity (P-gp(high)) are unresponsive to TCR stimulation in vitro but can be activated by PMA plus ionomycin. The proportion of these hyporesponsive cells increases considerably with age. The earliest events in T cell activation were studied in P-gp(high) and P-gp(low) CD4 memory cells at the single-cell level using confocal immunofluorescence methods. Recruitment of both linker for activation of T cells (LAT) and protein kinase C-theta to the immunological synapse, i.e., the site of T cell interaction with stimulator cells, was greatly impaired in P-gp(high) cells from both young and old mice. Translocation of NF-AT to the nucleus, CD69 expression, and proliferative capacity were also diminished to a similar extent in P-gp(high) cells under the same activation conditions. In contrast, movement of c-Cbl to the synapse region occurred in a high proportion of CD4 memory T cells regardless of P-gp subset or age. Moreover, although P-gp(low) cells frequently recruited both c-Cbl and LAT to the APC synapse, cells in the less responsive P-gp(high) subset frequently relocated c-Cbl, but not LAT, to the interface region. In some systems, c-Cbl can act as a negative regulator of receptor-dependent tyrosine kinases, and alterations of c-Cbl to LAT ratios in the P-gp(high) subset may thus contribute to the hyporesponsiveness of this age-dependent, anergic memory cell population.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/biosynthesis
- Adaptor Proteins, Signal Transducing
- Aging/immunology
- Animals
- Antigens, CD/biosynthesis
- Antigens, Differentiation, T-Lymphocyte/biosynthesis
- Biological Transport/immunology
- CD4-Positive T-Lymphocytes/enzymology
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- Carrier Proteins/metabolism
- Cell Line
- Cell Nucleus/metabolism
- Clonal Anergy
- DNA-Binding Proteins/metabolism
- Immunologic Memory
- Isoenzymes/metabolism
- Lectins, C-Type
- Male
- Membrane Proteins
- Mice
- Mice, Inbred C57BL
- Mice, Inbred CBA
- Models, Immunological
- NFATC Transcription Factors
- Nuclear Proteins
- Phosphoproteins/metabolism
- Protein Kinase C/metabolism
- Protein Kinase C-theta
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-cbl
- T-Lymphocyte Subsets/enzymology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- Transcription Factors/metabolism
- Ubiquitin-Protein Ligases
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Affiliation(s)
- M D Eisenbraun
- Department of Pathology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
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202
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Abstract
Adapter molecules contain discrete modular domains that direct specific intermolecular interactions to orchestrate assembly of signaling complexes. A number of adapter proteins play critical roles in both positive and negative regulation of antigen-receptor signaling, influencing lymphocyte development and function.
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Affiliation(s)
- P S Myung
- Graduate Program of Immunology, University of Pennsylvania, The Leonard and Madlyn Abramson Family Cancer Research Institute, Philadelphia, PA 19104-6160, USA
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203
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Abstract
The past several years have seen the beginning of a shift in the way that TCR signal transduction is studied. Although many investigators continue to identify new molecules, particularly adaptor proteins, others have attempted to look at signaling events in a larger cellular context. Thus the identification of distinct formations of signaling molecules at junctions between T cells and antigen-presenting cells, the role of the cytoskeleton and the partitioning of molecules into specialized lipid subdomains have been the subjects of many publications. Such concepts are helping to assemble a blueprint of how the myriad adaptors and kinases fit together to effect T cell activation.
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Affiliation(s)
- L P Kane
- Department of Medicine, The Howard Hughes Medical Institute, University of California (San Francisco), San Francisco, CA 94143-0795, USA
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204
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Langlet C, Bernard AM, Drevot P, He HT. Membrane rafts and signaling by the multichain immune recognition receptors. Curr Opin Immunol 2000; 12:250-5. [PMID: 10781401 DOI: 10.1016/s0952-7915(00)00084-4] [Citation(s) in RCA: 189] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The recent recognition of the presence of rafts in the plasma membrane and of their involvement in cell signaling has strongly stimulated the search for their function in receptor-mediated signal transduction in lymphocytes. Recent progress suggests that a general feature of membrane rafts is to serve as platforms wherein the signaling cascades triggered through different multichain immune recognition receptors (e.g. the TCR, BCR and FcepsilonRI) are initiated and organized.
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Affiliation(s)
- C Langlet
- Centre d'Immunologie, Institut National de la Santé et de la Recherche Médicale/Centre National de la Recherche Scientifique (INSERM-CNRS) de Marseille-Luminy, Marseille, 13288, France
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205
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Prieschl EE, Csonga R, Novotny V, Kikuchi GE, Baumruker T. Glycosphingolipid-induced relocation of Lyn and Syk into detergent-resistant membranes results in mast cell activation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:5389-97. [PMID: 10799903 DOI: 10.4049/jimmunol.164.10.5389] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Sphingosine, sphingosine-1-phosphate, and the more complex sphingolipid ceramide exert strong immunomodulatory effects on a variety of leukocytes. However, little is known regarding such a potential of glycosphingolipids, a class of sugar derivatives of sphingosine. Here we demonstrate that galactosylsphingosine, one of the smallest representatives of this group, accumulates in the detergent-resistant membranes resulting in the relocation of the tyrosine kinases Lyn and Syk into this compartment. The result of this is an enhanced tyrosine phosphorylation and kinase activity leading to priming and activation of mast cells by conveying a weak yet significant activation of the mitogen-activated protein kinase pathway(s). In comparison to IgE/Ag triggering, galactosylsphingosine stimulates the mitogen-activated protein kinase pathway more rapidly and favors c-Jun NH2-terminal kinase 1 activation over extracellular signal-regulatory kinase 1 and 2. At the transcription factor level, this "ultratransient signaling event" results in an activation of JunD as the predominant AP-1 component. In this respect, the effects of galactosylsphingosine are clearly distinct from the signaling elicited by other sphingolipids without the sugar moiety, such as sphingosine-1-phosphate.
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Affiliation(s)
- E E Prieschl
- Department of Immunology, Novartis Research Institute, Vienna, Austria.
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206
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Hühn J, Ehrlich S, Fleischer B, von Bonin A. Molecular analysis of CD26-mediated signal transduction in T cells. Immunol Lett 2000; 72:127-32. [PMID: 10841948 DOI: 10.1016/s0165-2478(00)00170-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
CD26 or dipeptidylpeptidase IV (DPP IV) is a cell surface protease involved in T cell activation. It is a type II transmembrane glycoprotein consisting of a large extracellular part, a single transmembrane region and a short cytoplasmic tail without any common signalling motifs. To eluciate the mechanisms involved in CD26-mediated signalling we have constructed C-terminal deletion mutants of the human CD26 molecule and transfected them into murine T cell hybridomas. Stimulation experiments show that most of the extracellular part of CD26 can be deleted without affecting its costimulatory activity. The membrane proximal glycosylation rich region of CD26 is sufficient to transduce costimulatory signals. Activation of T cells via CD26, however, is not mediated by the important T cell receptor associated adaptor proteins LAT and TRIM as shown in colocalization assays.
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MESH Headings
- Animals
- Antigens, CD/biosynthesis
- Antigens, Differentiation, T-Lymphocyte/biosynthesis
- Biomarkers/analysis
- Dipeptidyl Peptidase 4/immunology
- Dipeptidyl Peptidase 4/metabolism
- Dipeptidyl Peptidase 4/physiology
- Glycosylation
- Humans
- Lectins, C-Type
- Lymphocyte Activation
- Membrane Proteins/biosynthesis
- Mice
- Mice, Inbred AKR
- Mutagenesis, Site-Directed
- Receptors, Antigen, T-Cell/biosynthesis
- Receptors, Antigen, T-Cell, gamma-delta/biosynthesis
- Signal Transduction/immunology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- Tumor Cells, Cultured
- Up-Regulation/immunology
- ras Proteins/physiology
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Affiliation(s)
- J Hühn
- Nocht-Institute for Tropical Medicine, Bernhard-Nochtstr. 74, D-20359, Hamburg, Germany
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207
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Saitoh S, Arudchandran R, Manetz TS, Zhang W, Sommers CL, Love PE, Rivera J, Samelson LE. LAT is essential for Fc(epsilon)RI-mediated mast cell activation. Immunity 2000; 12:525-35. [PMID: 10843385 DOI: 10.1016/s1074-7613(00)80204-6] [Citation(s) in RCA: 290] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The linker molecule LAT is a substrate of the tyrosine kinases activated following TCR engagement of T cells. LAT is also expressed in platelets, NK, and mast cells. Although LAT-deficient mice contain normal numbers of mast cells, we found that LAT-deficient mice were resistant to IgE-mediated passive systemic anaphylaxis. LAT-deficient bone marrow-derived mast cells (BMMC) showed normal growth and development. Whereas tyrosine phosphorylation of Fc(epsilon)RI, Syk, and Vav was intact in LAT-deficient BMMCs following Fc(epsilon)RI engagement, tyrosine phosphorylation of SLP-76, PLC-gamma1, and PLC-gamma2 and calcium mobilization were dramatically reduced. LAT-deficient BMMCs also exhibited profound defects in activation of MAPK, degranulation, and cytokine production after Fc(epsilon)RI cross-linking. These results show that LAT plays a critical role in Fc(epsilon)RI-mediated signaling in mast cells.
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Affiliation(s)
- S Saitoh
- Laboratory of Cellular and Molecular Biology, Division of Basic Science, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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208
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Potentiation of CD3-induced expression of the linker for activation of T cells (LAT) by the calcineurin inhibitors cyclosporin A and FK506. Blood 2000. [DOI: 10.1182/blood.v95.9.2733.009k06_2733_2741] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The activation of blood cells, including T cells, triggers intracellular signals that control the expression of critical molecules, including cytokines and cytokine receptors. We show that T-cell receptor (TCR) ligation increases the cellular level of the protein linker for activation of T cells (LAT), a molecule critical for T-cell development and function. T-cell activation increased LAT messenger RNA, as determined by reverse transcription–polymerase chain reaction and by Northern blotting. The TCR-induced increase in LAT expression involved the activation of the serine/threonine kinases PKC and MEK, because inhibitors of these kinases blocked the increase in LAT. Accordingly, the PKC activator phorbol myristate acetate up-regulated LAT expression. Strikingly, the calcineurin inhibitors cyclosporin A (CsA) and FK506 strongly potentiated TCR-induced LAT expression, suggesting that the activation of calcineurin following TCR ligation negatively regulates LAT expression. Accordingly, Ca++ ionophores, which can activate calcineurin by increasing intracellular Ca++, blocked the TCR-induced increase in cellular LAT. CsA and FK506 blocked the Ca++ionophores' inhibitory effect on LAT expression. Notably, CsA and FK506 preferentially up-regulated TCR-induced LAT expression; under the same conditions, these compounds did not increase the expression of 14 other molecules that previously had been implicated in T-cell activation. These data show that TCR-induced LAT expression involves the activation of the PKC-Erk pathway and is negatively regulated by the activation of calcineurin. Furthermore, the potentiation of TCR-induced LAT expression by CsA and FK506 suggests that the action of these agents involves up-regulating the cellular level of critical signaling molecules. These findings may have important therapeutic implications.
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209
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Goitsuka R, Kanazashi H, Sasanuma H, Fujimura Y, Hidaka Y, Tatsuno A, Ra C, Hayashi K, Kitamura D. A BASH/SLP-76-related adaptor protein MIST/Clnk involved in IgE receptor-mediated mast cell degranulation. Int Immunol 2000; 12:573-80. [PMID: 10744659 DOI: 10.1093/intimm/12.4.573] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cross-linking of the high-affinity IgE receptor (FcepsilonRI) on mast cells by IgE-antigen complex triggers signal transduction cascades leading to the release of inflammatory mediators and production of cytokines, which are critical for the development of allergic reactions. We have identified a novel member of the BASH/SLP-76 immunoreceptor-coupled adaptor family expressed in mast cells, termed MIST (for mast cell immunoreceptor signal transducer), which has later been found to be identical to a recently reported cytokine-dependent hemopoietic cell linker, Clnk. Upon FcepsilonRI cross-linking, MIST/Clnk is tyrosine phosphorylated and associates with signaling proteins, phospholipase Cgamma, Vav, Grb2 and linker for activation of T cells (LAT). Overexpression of a mutant form of MIST/Clnk inhibited FcepsilonRI-mediated degranulation, increase in intracellular Ca(2+), NF-AT activation and phosphorylation of LAT. As a crucial signaling component for FcepsilonRI-induced mast cell degranulation, MIST/Clnk might serve as a target for anti-allergic therapy.
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Affiliation(s)
- R Goitsuka
- Division of Molecular Biology, Research Institute for Biological Sciences, Science University of Tokyo, 2669 Yamazaki, Noda, Chiba 278, Japan
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210
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Abstract
SLP-76 and LAT are two recently identified adapter proteins that are involved in the signal transduction cascade initiated by engagement of the TCR. The role of these two molecules in thymocyte development has become clearer following studies of gene targeted mice. The data indicate that SLP-76 and LAT are each critical for the expansion and differentiation of double-negative thymocytes and that SLP-76 is essential for allelic exclusion at the TCRbeta locus.
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Affiliation(s)
- V I Pivniouk
- Division of Immunology, Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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211
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Lemay S, Davidson D, Latour S, Veillette A. Dok-3, a novel adapter molecule involved in the negative regulation of immunoreceptor signaling. Mol Cell Biol 2000; 20:2743-54. [PMID: 10733577 PMCID: PMC85490 DOI: 10.1128/mcb.20.8.2743-2754.2000] [Citation(s) in RCA: 159] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Adapters are typically viewed as molecules coordinating the recruitment of positive effectors of cell signaling. Herein, we report the identification of Dok-3, a novel adapter molecule belonging to the Dok family. Our studies show that Dok-3 is highly expressed in several hemopoietic cell types, including B cells and macrophages. It undergoes rapid tyrosine phosphorylation in response to immunoreceptor-mediated cellular activation, seemingly as a result of the action of Src family kinases. This phosphorylation induces the binding of Dok-3 to at least two inhibitory molecules, the 5' inositol phosphatase SHIP and the protein tyrosine kinase Csk. We also demonstrate that augmented expression of wild-type Dok-3 in a B-cell line results in an inhibition of immunoreceptor-mediated nuclear factor of activated T-cells (NFAT) activation and cytokine release, while introduction of a Dok-3 mutant with impaired ability to associate with SHIP and Csk enhances B-cell responsiveness. Taken together, these results indicate that Dok-3 is an adapter involved in the recruitment of inhibitory molecules and that it may play a significant role in the negative regulation of immunoreceptor signaling in hemopoietic cells such as B cells and macrophages.
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Affiliation(s)
- S Lemay
- McGill Cancer Centre, McGill University, Montréal, Québec, Canada H3G 1Y6
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212
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Affiliation(s)
- X R Bustelo
- Department of Pathology, State University of New York at Stony Brook, Stony Brook, New York 11794, USA.
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213
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Salojin KV, Zhang J, Meagher C, Delovitch TL. ZAP-70 is essential for the T cell antigen receptor-induced plasma membrane targeting of SOS and Vav in T cells. J Biol Chem 2000; 275:5966-75. [PMID: 10681590 DOI: 10.1074/jbc.275.8.5966] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Translocation of the SOS and Vav GDP/GTP exchange factors proximal to Ras and Rac GTPases localized in the plasma membrane glycolipid-enriched microdomains is a pivotal step required for T cell antigen receptor-induced T cell activation. Here we demonstrate that the T cell antigen receptor zeta-chain-associated ZAP-70 kinase and T cell antigen receptor zeta-chain immunoreceptor tyrosine-based activation motifs are essential for the membrane recruitment of SOS and Vav. Plasma membrane targeting of SOS or Vav begins with the assembly of ZAP-70 with Grb-2 and SOS. The subsequent tyrosine phosphorylation of LAT (linker for activation of T cell) by ZAP-70 leads to a shift in equilibrium from the ZAP-70.Grb-2.SOS(Vav) complex to the (Vav)SOS.Grb-2.LAT complex. This shift results in the targeting of SOS and Vav into glycolipid-enriched microdomains and initiation of the Ras and Rac signaling cascades involved in T cell activation, proliferation, and cytokine production.
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Affiliation(s)
- K V Salojin
- Autoimmunity/Diabetes Group, The John P. Robarts Research Institute, Department of Microbiology, University of Western Ontario, London, Ontario N6G 2V4, Canada
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214
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Abstract
Engagement of the T cell receptor leads to activation of several tyrosine kinases and phosphorylation of many intracellular proteins. This is followed by Ca2+ mobilization and activation of multiple biochemical pathways, including the Ras/MAPK cascade, and several downstream serine/threonine kinases. Membrane-associated adaptor proteins play an important role in T cell activation by coupling TCR ligation at the membrane to distal signalling cascades. Several new membrane associated adaptors have been identified in recent years. LAT (linker for activation of T cells) is an adaptor molecule, which following its phosphorylation associates with Grb2, Gads, PLC-gamma 1, and other signalling molecules. The functional importance of this molecule has been demonstrated by the study of LAT-deficient cell lines and LAT-deficient mice. Two other recently identified adaptor proteins, TRIM (T cell receptor interacting molecule) and SIT (SHP2-interacting transmembrane adaptor protein), which constitutively associate with several surface molecules, bind to PI3K and SHP2, respectively, after T cell activation and might also function in the TCR signalling pathway.
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Affiliation(s)
- W Zhang
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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215
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Bunnell SC, Diehn M, Yaffe MB, Findell PR, Cantley LC, Berg LJ. Biochemical interactions integrating Itk with the T cell receptor-initiated signaling cascade. J Biol Chem 2000; 275:2219-30. [PMID: 10636929 DOI: 10.1074/jbc.275.3.2219] [Citation(s) in RCA: 216] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Itk, a Tec family tyrosine kinase, acts downstream of Lck and phosphatidylinositol 3'-kinase to facilitate T cell receptor (TCR)-dependent calcium influxes and increases in extracellular-regulated kinase activity. Here we demonstrate interactions between Itk and crucial components of TCR-dependent signaling pathways. First, the inositide-binding pocket of the Itk pleckstrin homology domain directs the constitutive association of Itk with buoyant membranes that are the primary site of TCR activation and are enriched in both Lck and LAT. This association is required for the transphosphorylation of Itk. Second, the Itk proline-rich region binds to Grb2 and LAT. Third, the Itk Src homology (SH3) 3 and SH2 domains interact cooperatively with Syk-phosphorylated SLP-76. Notably, SLP-76 contains a predicted binding motif for the Itk SH2 domain and binds to full-length Itk in vitro. Finally, we show that kinase-inactive Itk can antagonize the SLP-76-dependent activation of NF-AT. The inhibition of NF-AT activation depends on the Itk pleckstrin homology domain, proline-rich region, and SH2 domain. Together, these observations suggest that multivalent interactions recruit Itk to LAT-nucleated signaling complexes and facilitate the activation of LAT-associated phospholipase Cgamma1 by Itk.
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Affiliation(s)
- S C Bunnell
- Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
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216
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Abstract
A ubiquitous signaling event in hormonal responses is the phospholipase C (PLC)-catalyzed hydrolysis of phosphatidylinositol 4, 5-bisphosphate to produce the metabolite second messenger molecules inositol 1,4,5-trisphosphate and diacylglycerol. The former provokes a transient increase in intracellular free Ca(2+), while the latter serves as a direct activator of protein kinase C. In tyrosine kinase-dependent signaling pathways this reaction is mediated by the PLC-gamma isozymes. These are direct substrates of many tyrosine kinases in a wide variety of cell types. The mechanism of PLC-gamma activation involves its association with and phosphorylation by receptor and non-receptor tyrosine kinases, as well as interaction with specialized adaptor molecules and, perhaps, other second messenger molecules. However, the biochemistry of PLC-gamma is at a more advanced state than a clear understanding of exactly how this signaling element functions in the generation of a mitogenic response.
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Affiliation(s)
- G Carpenter
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, 37232-0146, USA.
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217
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Abstract
Of the past several years progress in understanding TCR signal transduction has led to the discovery of new kinases, adapter molecules and multiple signaling pathways. The study of molecules such as LAT, SLP-76, FYB, SKAP-55 and VAV have revealed multiple mechanisms with which to control the activation of downstream signaling pathways through RAS, PLC gamma-1 and ERK/MAPK. Signaling through SLP-76 can play a role in TCR-induced cytoskeleton changes through activation of effector molecules in the RAC/RHO-family of GTPases. In addition, SLP-76 through its association with FYB/FYN-T appears to play a role in IL-2 gene transcription following TCR activation. Finally, these newly identified adaptor molecules, such as LAT, may be crucial in T-cell activation by enhancing the recruitment of critical kinases to glycolipid-enriched microdomains of the activated T-cell receptor complex.
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Affiliation(s)
- J S Kennedy
- Department of Cancer Immunology and AIDS, Harvard Medical School, Boston, USA
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