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Abstract
Triggering of cell-mediated immunity is largely dependent on the recognition of foreign or abnormal molecules by a myriad of cell surface-bound receptors. Many activating immune receptors do not possess any intrinsic signaling capacity but instead form noncovalent complexes with one or more dimeric signaling modules that communicate with a common set of kinases to initiate intracellular information-transfer pathways. This modular architecture, where the ligand binding and signaling functions are detached from one another, is a common theme that is widely employed throughout the innate and adaptive arms of immune systems. The evolutionary advantages of this highly adaptable platform for molecular recognition are visible in the variety of ligand-receptor interactions that can be linked to common signaling pathways, the diversification of receptor modules in response to pathogen challenges, and the amplification of cellular responses through incorporation of multiple signaling motifs. Here we provide an overview of the major classes of modular activating immune receptors and outline the current state of knowledge regarding how these receptors assemble, recognize their ligands, and ultimately trigger intracellular signal transduction pathways that activate immune cell effector functions.
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Affiliation(s)
- Richard Berry
- Infection and Immunity Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University , Clayton, Victoria 3800, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, Monash University , Clayton, Victoria 3800, Australia
| | - Matthew E Call
- Structural Biology Division, The Walter and Eliza Hall Institute of Medical Research , Parkville, Victoria 3052, Australia.,Department of Medical Biology, University of Melbourne , Parkville, Victoria 3052, Australia
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2
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A conserved αβ transmembrane interface forms the core of a compact T-cell receptor-CD3 structure within the membrane. Proc Natl Acad Sci U S A 2016; 113:E6649-E6658. [PMID: 27791034 DOI: 10.1073/pnas.1611445113] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The T-cell antigen receptor (TCR) is an assembly of eight type I single-pass membrane proteins that occupies a central position in adaptive immunity. Many TCR-triggering models invoke an alteration in receptor complex structure as the initiating event, but both the precise subunit organization and the pathway by which ligand-induced alterations are transferred to the cytoplasmic signaling domains are unknown. Here, we show that the receptor complex transmembrane (TM) domains form an intimately associated eight-helix bundle organized by a specific interhelical TCR TM interface. The salient features of this core structure are absolutely conserved between αβ and γδ TCR sequences and throughout vertebrate evolution, and mutations at key interface residues caused defects in the formation of stable TCRαβ:CD3δε:CD3γε:ζζ complexes. These findings demonstrate that the eight TCR-CD3 subunits form a compact and precisely organized structure within the membrane and provide a structural basis for further investigation of conformationally regulated models of transbilayer TCR signaling.
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Goplen NP, Saxena V, Knudson KM, Schrum AG, Gil D, Daniels MA, Zamoyska R, Teixeiro E. IL-12 Signals through the TCR To Support CD8 Innate Immune Responses. THE JOURNAL OF IMMUNOLOGY 2016; 197:2434-43. [PMID: 27521342 DOI: 10.4049/jimmunol.1600037] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 07/13/2016] [Indexed: 01/19/2023]
Abstract
CD8 T cells must integrate antigenic and inflammatory signals to differentiate into efficient effector and memory T cells able to protect us from infections. The mechanisms by which TCR signaling and proinflammatory cytokine receptor signaling cooperate in these processes are poorly defined. In this study, we show that IL-12 and other proinflammatory cytokines transduce signals through the TCR signalosome in a manner that requires Fyn activity and self-peptide-MHC (self-pMHC) interactions. This mechanism is crucial for CD8 innate T cell functions. Loss of Fyn activity or blockade of self-pMHC interactions severely impaired CD8 T cell IFN-γ and NKG2D expression, proliferation, and cytotoxicity upon cytokine-mediated bystander activation. Most importantly, in the absence of self-pMHC interactions, CD8 memory T cells fail to undergo bystander activation upon an unrelated infection. Thus, CD8 T cell bystander activation, although independent of cognate Ag, still requires self-pMHC and TCR signaling.
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Affiliation(s)
- Nicholas P Goplen
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65212
| | - Vikas Saxena
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65212
| | - Karin M Knudson
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65212
| | - Adam G Schrum
- Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN 55905; and
| | - Diana Gil
- Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN 55905; and
| | - Mark A Daniels
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65212
| | - Rose Zamoyska
- Institute of Immunology and Infection Research, Centre for Immunity, Infection and Evolution, Ashworth Laboratories, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
| | - Emma Teixeiro
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65212;
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Cunningham CA, Knudson KM, Peng BJ, Teixeiro E, Daniels MA. The POSH/JIP-1 scaffold network regulates TCR-mediated JNK1 signals and effector function in CD8+T cells. Eur J Immunol 2013; 43:3361-71. [DOI: 10.1002/eji.201343635] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 07/15/2013] [Accepted: 08/16/2013] [Indexed: 12/21/2022]
Affiliation(s)
- Cody A. Cunningham
- Department of Molecular Microbiology and Immunology & Department of Surgery; Center for Cellular and Molecular Immunology, School of Medicine, University of Missouri; Columbia MO USA
| | - Karin M. Knudson
- Department of Molecular Microbiology and Immunology & Department of Surgery; Center for Cellular and Molecular Immunology, School of Medicine, University of Missouri; Columbia MO USA
| | - Binghao J. Peng
- Department of Molecular Microbiology and Immunology & Department of Surgery; Center for Cellular and Molecular Immunology, School of Medicine, University of Missouri; Columbia MO USA
| | - Emma Teixeiro
- Department of Molecular Microbiology and Immunology & Department of Surgery; Center for Cellular and Molecular Immunology, School of Medicine, University of Missouri; Columbia MO USA
| | - Mark A. Daniels
- Department of Molecular Microbiology and Immunology & Department of Surgery; Center for Cellular and Molecular Immunology, School of Medicine, University of Missouri; Columbia MO USA
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Marcu-Malina V, van Dorp S, Kuball J. Re-targeting T-cells against cancer by gene-transfer of tumor-reactive receptors. Expert Opin Biol Ther 2010; 9:579-91. [PMID: 19368527 DOI: 10.1517/14712590902887018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Adoptive transfer of T-lymphocytes is a promising treatment for a variety of malignancies, but is often not feasible due to difficulties in generating T-cells reactive with the targeted antigen from patients. To facilitate rapid generation of cells for therapy, T-cells can be programmed with genes encoding for an antigen-specific T-cell receptor (TCR) or chimeric receptors. OBJECTIVE To discuss the molecular design and selected pitfalls of TCR gene modified T-cells and T-cells expressing chimeric receptors, so called T-bodies. METHODS A selected review of the recent literature. CONCLUSION Clinical trials report so far only limited efficacy of adoptively transferred genetically modified T-cells. However, the recent progress in engineering tumor-reactive T cells is providing a promising basis to further explore this treatment modality.
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Affiliation(s)
- Victoria Marcu-Malina
- Department of Hematology and VanCreveld Clinic, University Medical Center Utrecht, Utrecht, The Netherlands
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Roth L, Nasarre C, Dirrig-Grosch S, Aunis D, Crémel G, Hubert P, Bagnard D. Transmembrane domain interactions control biological functions of neuropilin-1. Mol Biol Cell 2007; 19:646-54. [PMID: 18045991 DOI: 10.1091/mbc.e07-06-0625] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Neuropilin-1 (NRP1) is a transmembrane receptor playing a pivotal role in the control of semaphorins and VEGF signaling pathways. The exact mechanism controlling semaphorin receptor complex formation is unknown. A structural analysis and modeling of NRP1 revealed a putative dimerization GxxxG motif potentially important for NRP1 dimerization and oligomerization. Our data show that this motif mediates the dimerization of the transmembrane domain of NRP1 as demonstrated by a dimerization assay (ToxLuc assay) performed in natural membrane and FRET analysis. A synthetic peptide derived from the transmembrane segment of NRP1 abolished the inhibitory effect of Sema3A. This effect depends on the capacity of the peptide to interfere with NRP1 dimerization and the formation of oligomeric complexes. Mutation of the GxxxG dimerization motif in the transmembrane domain of NRP1 confirmed its biological importance for Sema3A signaling. Overall, our results shed light on an essential step required for semaphorin signaling and provide novel evidence for the crucial role of transmembrane domain of bitopic protein containing GxxxG motif in the formation of receptor complexes that are a prerequisite for cell signaling.
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Affiliation(s)
- Lise Roth
- INSERM U575 Physiopathologie du Système Nerveux, Université Louis Pasteur, 67084 Strasbourg, France
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Daniels MA, Teixeiro E, Gill J, Hausmann B, Roubaty D, Holmberg K, Werlen G, Holländer GA, Gascoigne NRJ, Palmer E. Thymic selection threshold defined by compartmentalization of Ras/MAPK signalling. Nature 2006; 444:724-9. [PMID: 17086201 DOI: 10.1038/nature05269] [Citation(s) in RCA: 468] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Accepted: 09/18/2006] [Indexed: 01/02/2023]
Abstract
A healthy individual can mount an immune response to exogenous pathogens while avoiding an autoimmune attack on normal tissues. The ability to distinguish between self and non-self is called 'immunological tolerance' and, for T lymphocytes, involves the generation of a diverse pool of functional T cells through positive selection and the removal of overtly self-reactive thymocytes by negative selection during T-cell ontogeny. To elucidate how thymocytes arrive at these cell fate decisions, here we have identified ligands that define an extremely narrow gap spanning the threshold that distinguishes positive from negative selection. We show that, at the selection threshold, a small increase in ligand affinity for the T-cell antigen receptor leads to a marked change in the activation and subcellular localization of Ras and mitogen-activated protein kinase (MAPK) signalling intermediates and the induction of negative selection. The ability to compartmentalize signalling molecules differentially in the cell endows the thymocyte with the ability to convert a small change in analogue input (affinity) into a digital output (positive versus negative selection) and provides the basis for establishing central tolerance.
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Affiliation(s)
- Mark A Daniels
- Laboratory of Transplantation Immunology and Nephrology, Department of Research, University Hospital-Basel, Hebelstrasse 20, 4031 Basel, Switzerland
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Chen Q, Coffey A, Bourgoin SG, Gadina M. Cytohesin binder and regulator augments T cell receptor-induced nuclear factor of activated T Cells.AP-1 activation through regulation of the JNK pathway. J Biol Chem 2006; 281:19985-94. [PMID: 16702224 DOI: 10.1074/jbc.m601629200] [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: 12/31/2022] Open
Abstract
Cytohesin binder and regulator (Cybr; also known as CYTIP, CASP, and PSCDBP) is a cytokine-induced gene preferentially expressed in hematopoietic tissues and in T helper 1 cells. Cybr protein associates with members of the cytohesin family, which are known ADP-ribosylation factors-GDP/GTP exchange factors, and its functions appear to regulate lymphocyte adhesion and cell-cell contact. Here we show that Cybr mRNA and protein levels are increased upon T cell receptor engagement. Cybr expression then influences T cell receptor-dependent signaling events, such as nuclear factor of activated T cells and AP-1 transcriptional activity. In addition, expression of Cybr results in increased T cell receptor-mediated activation of the Rho/Rac exchange factor Vav and of the JNK-p38 MAPK signaling pathway. The effects of Cybr on nuclear factor of activated T cells and AP-1 are dependent on MAPK activation, and enhanced activation of this cascade results in cooperation between the two transcription factors in the regulation of gene expression. These findings provide the first evidence that the adaptor protein Cybr not only regulates lymphocyte adhesion and cell-cell interaction but also contributes to the regulation of the signaling cascade and of the genetic program downstream of the T cell receptor.
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Affiliation(s)
- Qian Chen
- Division of Infection and Immunity, Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast BT9 7BL, UK
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Alonso R, Rodríguez MC, Pindado J, Merino E, Mérida I, Izquierdo M. Diacylglycerol kinase alpha regulates the secretion of lethal exosomes bearing Fas ligand during activation-induced cell death of T lymphocytes. J Biol Chem 2005; 280:28439-50. [PMID: 15870081 DOI: 10.1074/jbc.m501112200] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Fas ligand (FasL) mediates both apoptotic and inflammatory responses in the immune system. FasL function critically depends on the different forms of FasL; soluble Fas ligand lacking the transmembrane and cytoplasmic domains is a poor mediator of apoptosis, whereas full-length, membrane-associated FasL (mFasL) is pro-apoptotic. mFasL can be released from T lymphocytes, via the secretion of mFasL-bearing exosomes. mFasL in exosomes retains its activity in triggering Fas-dependent apoptosis, providing an alternative mechanism of cell death that does not necessarily imply cell-to-cell contact. Diacylglycerol kinase alpha (DGKalpha), a diacylglycerol (DAG)-consuming enzyme, is involved in the attenuation of DAG-derived responses initiated at the plasma membrane that lead to T lymphocyte activation. Here we studied the role of DGKalpha on activation-induced cell death on a T cell line and primary T lymphoblasts. The inhibition of DGKalpha increases the secretion of lethal exosomes bearing mFas ligand and subsequent apoptosis. On the contrary, the overactivation of the DGKalpha pathway inhibits exosome secretion and subsequent apoptosis. DGKalpha was found associated with the trans-Golgi network and late endosomal compartments. Our results support the hypothesis that the DGKalpha effect on apoptosis occurs via the regulation of the release of lethal exosomes by the exocytic pathway, and point out that the spatial orchestration of the different pools of DAG (plasma membrane and Golgi membranes) by DGKalpha is crucial for the control of cell activation and also for the regulation of the secretion of lethal exosomes, which in turn controls cell death.
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Affiliation(s)
- Roberto Alonso
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas-Universidad de Valladolid, Facultad de Medicina, Ramón y Cajal, 7, 47005 Valladolid, Spain
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