1
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Moroi AJ, Newman PJ. The LAT Rheostat as a Regulator of Megakaryocyte Activation. Thromb Haemost 2024. [PMID: 38788774 DOI: 10.1055/a-2332-6321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2024]
Abstract
BACKGROUND Specifically positioned negatively charged residues within the cytoplasmic domain of the adaptor protein, linker for the activation of T cells (LAT), have been shown to be important for efficient phosphorylation of tyrosine residues that function to recruit cytosolic proteins downstream of immunoreceptor tyrosine-based activation motif (ITAM) receptor signaling. LAT tyrosine 132-the binding site for PLC-γ2-is a notable exception, preceded instead by a glycine, making it a relatively poor substrate for phosphorylation. Mutating Gly131 to an acidic residue has been shown in T cells to enhance ITAM-linked receptor-mediated signaling. Whether this is generally true in other cell types is not known. METHODS To examine whether LAT Gly131 restricts ITAM signaling in cells of the megakaryocyte lineage, we introduced an aspartic acid at this position in human induced pluripotent stem cells (iPSCs), differentiated them into megakaryocytes, and examined its functional consequences. RESULTS iPSCs expressing G131D LAT differentiated and matured into megakaryocytes normally, but exhibited markedly enhanced reactivity to glycoprotein VI (GPVI)-agonist stimulation. The rate and extent of LAT Tyr132 and PLC-γ2 phosphorylation, and proplatelet formation on GPVI-reactive substrates, were also enhanced. CONCLUSION These data demonstrate that a glycine residue at the -1 position of LAT Tyr132 functions as a kinetic bottleneck to restrain Tyr132 phosphorylation and signaling downstream of ITAM receptor engagement in the megakaryocyte lineage. These findings may have translational applications in the burgeoning field of in vitro platelet bioengineering.
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Affiliation(s)
- Alyssa J Moroi
- Blood Research Institute, Versiti Blood Center of Wisconsin, Milwaukee, Wisconsin, United States
| | - Peter J Newman
- Blood Research Institute, Versiti Blood Center of Wisconsin, Milwaukee, Wisconsin, United States
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Department of Cell Biology, Neurobiology and, Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
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2
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Weiss A. Peeking Into the Black Box of T Cell Receptor Signaling. Annu Rev Immunol 2024; 42:1-20. [PMID: 37788477 DOI: 10.1146/annurev-immunol-090222-112028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
I have spent more than the last 40 years at the University of California, San Francisco (UCSF), studying T cell receptor (TCR) signaling. I was blessed with supportive mentors, an exceptionally talented group of trainees, and wonderful collaborators and colleagues during my journey who have enabled me to make significant contributions to our understanding of how the TCR initiates signaling. TCR signaling events contribute to T cell development as well as to mature T cell activation and differentiation.
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Affiliation(s)
- Arthur Weiss
- Division of Rheumatology, Department of Medicine, University of California, San Francisco, California, USA;
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3
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Fernández-Aguilar LM, Vico-Barranco I, Arbulo-Echevarria MM, Aguado E. A Story of Kinases and Adaptors: The Role of Lck, ZAP-70 and LAT in Switch Panel Governing T-Cell Development and Activation. BIOLOGY 2023; 12:1163. [PMID: 37759563 PMCID: PMC10525366 DOI: 10.3390/biology12091163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/18/2023] [Accepted: 08/20/2023] [Indexed: 09/29/2023]
Abstract
Specific antigen recognition is one of the immune system's features that allows it to mount intense yet controlled responses to an infinity of potential threats. T cells play a relevant role in the host defense and the clearance of pathogens by means of the specific recognition of peptide antigens presented by antigen-presenting cells (APCs), and, to do so, they are equipped with a clonally distributed antigen receptor called the T-cell receptor (TCR). Upon the specific engagement of the TCR, multiple intracellular signals are triggered, which lead to the activation, proliferation and differentiation of T lymphocytes into effector cells. In addition, this signaling cascade also operates during T-cell development, allowing for the generation of cells that can be helpful in the defense against threats, as well as preventing the generation of autoreactive cells. Early TCR signals include phosphorylation events in which the tyrosine kinases Lck and ZAP70 are involved. The sequential activation of these kinases leads to the phosphorylation of the transmembrane adaptor LAT, which constitutes a signaling hub for the generation of a signalosome, finally resulting in T-cell activation. These early signals play a relevant role in triggering the development, activation, proliferation and apoptosis of T cells, and the negative regulation of these signals is key to avoid aberrant processes that could generate inappropriate cellular responses and disease. In this review, we will examine and discuss the roles of the tyrosine kinases Lck and ZAP70 and the membrane adaptor LAT in these cellular processes.
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Grants
- PY20_01297 Consejería de Transformación Económica, Industria, Conocimiento y Universidades, Junta de Andalucía, Spain
- PID2020-113943RB-I00 Agencia Estatal de Investigación, Ministerio de Ciencia e Innovación, Spain
- PR2022-037 University of Cádiz
- PAIDI2020/DOC_01433 Consejería de Transformación Económica, Industria, Conocimiento y Universidades, Junta de Andalucía, Spain
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Affiliation(s)
- Luis M. Fernández-Aguilar
- Institute for Biomedical Research of Cadiz (INIBICA), 11009 Cadiz, Spain; (L.M.F.-A.); (I.V.-B.); (M.M.A.-E.)
- Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cadiz, 11002 Cadiz, Spain
| | - Inmaculada Vico-Barranco
- Institute for Biomedical Research of Cadiz (INIBICA), 11009 Cadiz, Spain; (L.M.F.-A.); (I.V.-B.); (M.M.A.-E.)
- Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cadiz, 11002 Cadiz, Spain
| | - Mikel M. Arbulo-Echevarria
- Institute for Biomedical Research of Cadiz (INIBICA), 11009 Cadiz, Spain; (L.M.F.-A.); (I.V.-B.); (M.M.A.-E.)
- Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cadiz, 11002 Cadiz, Spain
| | - Enrique Aguado
- Institute for Biomedical Research of Cadiz (INIBICA), 11009 Cadiz, Spain; (L.M.F.-A.); (I.V.-B.); (M.M.A.-E.)
- Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cadiz, 11002 Cadiz, Spain
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4
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Sandouk A, Xu Z, Baruah S, Tremblay M, Hopkins JB, Chakravarthy S, Gakhar L, Schnicker NJ, Houtman JCD. GRB2 dimerization mediated by SH2 domain-swapping is critical for T cell signaling and cytokine production. Sci Rep 2023; 13:3505. [PMID: 36864087 PMCID: PMC9981690 DOI: 10.1038/s41598-023-30562-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 02/25/2023] [Indexed: 03/04/2023] Open
Abstract
GRB2 is an adaptor protein required for facilitating cytoplasmic signaling complexes from a wide array of binding partners. GRB2 has been reported to exist in either a monomeric or dimeric state in crystal and solution. GRB2 dimers are formed by the exchange of protein segments between domains, otherwise known as "domain-swapping". Swapping has been described between SH2 and C-terminal SH3 domains in the full-length structure of GRB2 (SH2/C-SH3 domain-swapped dimer), as well as between α-helixes in isolated GRB2 SH2 domains (SH2/SH2 domain-swapped dimer). Interestingly, SH2/SH2 domain-swapping has not been observed within the full-length protein, nor have the functional influences of this novel oligomeric conformation been explored. We herein generated a model of full-length GRB2 dimer with an SH2/SH2 domain-swapped conformation supported by in-line SEC-MALS-SAXS analyses. This conformation is consistent with the previously reported truncated GRB2 SH2/SH2 domain-swapped dimer but different from the previously reported, full-length SH2/C-terminal SH3 (C-SH3) domain-swapped dimer. Our model is also validated by several novel full-length GRB2 mutants that favor either a monomeric or a dimeric state through mutations within the SH2 domain that abrogate or promote SH2/SH2 domain-swapping. GRB2 knockdown and re-expression of selected monomeric and dimeric mutants in a T cell lymphoma cell line led to notable defects in clustering of the adaptor protein LAT and IL-2 release in response to TCR stimulation. These results mirrored similarly-impaired IL-2 release in GRB2-deficient cells. These studies show that a novel dimeric GRB2 conformation with domain-swapping between SH2 domains and monomer/dimer transitions are critical for GRB2 to facilitate early signaling complexes in human T cells.
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Affiliation(s)
- Aline Sandouk
- Interdisciplinary Graduate Program in Immunology, University of Iowa, Iowa City, IA, 52242, USA
| | - Zhen Xu
- Protein and Crystallography Facility, University of Iowa, Iowa City, IA, 52242, USA
| | - Sankar Baruah
- Protein and Crystallography Facility, University of Iowa, Iowa City, IA, 52242, USA
| | - Mikaela Tremblay
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, 52242, USA
| | - Jesse B Hopkins
- Biophysics Collaborative Access Team, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Srinivas Chakravarthy
- Biophysics Collaborative Access Team, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Lokesh Gakhar
- Protein and Crystallography Facility, University of Iowa, Iowa City, IA, 52242, USA
- Department of Biochemistry and Molecular Biology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Nicholas J Schnicker
- Protein and Crystallography Facility, University of Iowa, Iowa City, IA, 52242, USA
| | - Jon C D Houtman
- Interdisciplinary Graduate Program in Immunology, University of Iowa, Iowa City, IA, 52242, USA.
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, 52242, USA.
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Arbulo-Echevarria MM, Vico-Barranco I, Zhang F, Fernandez-Aguilar LM, Chotomska M, Narbona-Sánchez I, Zhang L, Malissen B, Liang Y, Aguado E. Mutation of the glycine residue preceding the sixth tyrosine of the LAT adaptor severely alters T cell development and activation. Front Immunol 2022; 13:1054920. [PMID: 36569841 PMCID: PMC9768323 DOI: 10.3389/fimmu.2022.1054920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 11/21/2022] [Indexed: 12/12/2022] Open
Abstract
The LAT transmembrane adaptor is essential to transduce intracellular signals triggered by the TCR. Phosphorylation of its four C-terminal tyrosine residues (136, 175, 195, and 235 in mouse LAT) recruits several proteins resulting in the assembly of the LAT signalosome. Among those tyrosine residues, the one found at position 136 of mouse LAT plays a critical role for T cell development and activation. The kinetics of phosphorylation of this residue is delayed as compared to the three other C-terminal tyrosines due to a conserved glycine residue found at position 135. Mutation of this glycine into an aspartate residue (denoted LATG135D) increased TCR signaling and altered antigen recognition in human Jurkat T cells and ex vivo mouse T cells. Here, using a strain of LATG135D knockin mice, we showed that the LATG135D mutation modifies thymic development, causing an increase in the percentage of CD4+CD8+ double-positive cells, and a reduction in the percentage of CD4+ and CD8+ single-positive cells. Interestingly, the LATG135D mutation alters thymic development even in a heterozygous state. In the periphery, the LATG135D mutation reduces the percentage of CD8+ T cells and results in a small increment of γδ T cells. Remarkably, the LATG135D mutation dramatically increases the percentage of central memory CD8+ T cells. Finally, analysis of the proliferation and activation of T lymphocytes shows increased responses of T cells from mutant mice. Altogether, our results reinforce the view that the residue preceding Tyr136 of LAT constitutes a crucial checkpoint in T cell development and activation.
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Affiliation(s)
- Mikel M. Arbulo-Echevarria
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Universidad de Cádiz, Cádiz, Spain,Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain
| | - Inmaculada Vico-Barranco
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Universidad de Cádiz, Cádiz, Spain,Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain
| | - Fanghui Zhang
- Centre d’Immunologie de Marseille-Luminy (CIML), Aix Marseille Université, INSERM, CNRS, Marseille, France,Henan Key Laboratory for Immunology and Targeted Therapy, School of Laboratory Medicine, Xinxiang Medical University, Xinxiang, China
| | - Luis M. Fernandez-Aguilar
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Universidad de Cádiz, Cádiz, Spain,Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain
| | - Martyna Chotomska
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Universidad de Cádiz, Cádiz, Spain
| | - Isaac Narbona-Sánchez
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Universidad de Cádiz, Cádiz, Spain,Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain
| | - Lichen Zhang
- Henan Key Laboratory for Immunology and Targeted Therapy, School of Laboratory Medicine, Xinxiang Medical University, Xinxiang, China
| | - Bernard Malissen
- Centre d’Immunologie de Marseille-Luminy (CIML), Aix Marseille Université, INSERM, CNRS, Marseille, France,Laboratory of Immunophenomics, School of Laboratory Medicine, Xinxiang Medical University, Xinxiang, China
| | - Yinming Liang
- Henan Key Laboratory for Immunology and Targeted Therapy, School of Laboratory Medicine, Xinxiang Medical University, Xinxiang, China
| | - Enrique Aguado
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Universidad de Cádiz, Cádiz, Spain,Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain,*Correspondence: Enrique Aguado,
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6
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McAffee DB, O'Dair MK, Lin JJ, Low-Nam ST, Wilhelm KB, Kim S, Morita S, Groves JT. Discrete LAT condensates encode antigen information from single pMHC:TCR binding events. Nat Commun 2022; 13:7446. [PMID: 36460640 PMCID: PMC9718779 DOI: 10.1038/s41467-022-35093-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Accepted: 11/17/2022] [Indexed: 12/05/2022] Open
Abstract
LAT assembly into a two-dimensional protein condensate is a prominent feature of antigen discrimination by T cells. Here, we use single-molecule imaging techniques to resolve the spatial position and temporal duration of each pMHC:TCR molecular binding event while simultaneously monitoring LAT condensation at the membrane. An individual binding event is sufficient to trigger a LAT condensate, which is self-limiting, and neither its size nor lifetime is correlated with the duration of the originating pMHC:TCR binding event. Only the probability of the LAT condensate forming is related to the pMHC:TCR binding dwell time. LAT condenses abruptly, but after an extended delay from the originating binding event. A LAT mutation that facilitates phosphorylation at the PLC-γ1 recruitment site shortens the delay time to LAT condensation and alters T cell antigen specificity. These results identify a function for the LAT protein condensation phase transition in setting antigen discrimination thresholds in T cells.
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Affiliation(s)
- Darren B McAffee
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Mark K O'Dair
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Jenny J Lin
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Shalini T Low-Nam
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Kiera B Wilhelm
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Sungi Kim
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Shumpei Morita
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Jay T Groves
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA.
- Institute for Digital Molecular Analytics and Science, Nanyang Technological University, 59 Nanyang Drive, Singapore, 636921, Singapore.
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7
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T cell receptor (TCR) signaling in health and disease. Signal Transduct Target Ther 2021; 6:412. [PMID: 34897277 PMCID: PMC8666445 DOI: 10.1038/s41392-021-00823-w] [Citation(s) in RCA: 126] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 11/02/2021] [Accepted: 11/02/2021] [Indexed: 12/18/2022] Open
Abstract
Interaction of the T cell receptor (TCR) with an MHC-antigenic peptide complex results in changes at the molecular and cellular levels in T cells. The outside environmental cues are translated into various signal transduction pathways within the cell, which mediate the activation of various genes with the help of specific transcription factors. These signaling networks propagate with the help of various effector enzymes, such as kinases, phosphatases, and phospholipases. Integration of these disparate signal transduction pathways is done with the help of adaptor proteins that are non-enzymatic in function and that serve as a scaffold for various protein-protein interactions. This process aids in connecting the proximal to distal signaling pathways, thereby contributing to the full activation of T cells. This review provides a comprehensive snapshot of the various molecules involved in regulating T cell receptor signaling, covering both enzymes and adaptors, and will discuss their role in human disease.
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8
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Dinur-Schejter Y, Zaidman I, Mor-Shaked H, Stepensky P. The Clinical Aspect of Adaptor Molecules in T Cell Signaling: Lessons Learnt From Inborn Errors of Immunity. Front Immunol 2021; 12:701704. [PMID: 34456914 PMCID: PMC8397411 DOI: 10.3389/fimmu.2021.701704] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 07/26/2021] [Indexed: 12/22/2022] Open
Abstract
Adaptor molecules lack enzymatic and transcriptional activities. Instead, they exert their function by linking multiple proteins into intricate complexes, allowing for transmitting and fine-tuning of signals. Many adaptor molecules play a crucial role in T-cell signaling, following engagement of the T-cell receptor (TCR). In this review, we focus on Linker of Activation of T cells (LAT) and SH2 domain-containing leukocyte protein of 76 KDa (SLP-76). Monogenic defects in these adaptor proteins, with known roles in T-cell signaling, have been described as the cause of human inborn errors of immunity (IEI). We describe the current knowledge based on defects in cell lines, murine models and human patients. Germline mutations in Adhesion and degranulation adaptor protein (ADAP), have not resulted in a T-cell defect.
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Affiliation(s)
- Yael Dinur-Schejter
- Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel.,The Bone Marrow Transplantation and Cancer Immunotherapy Department, Hadassah Ein Kerem Medical Center, Jerusalem, Israel.,Allergy and Clinical Immunology Unit, Hadassah Ein-Kerem Medical Center, Jerusalem, Israel
| | - Irina Zaidman
- Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel.,The Bone Marrow Transplantation and Cancer Immunotherapy Department, Hadassah Ein Kerem Medical Center, Jerusalem, Israel
| | - Hagar Mor-Shaked
- Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel.,Monique and Jacques Roboh Department of Genetic Research, Hadassah Ein Kerem Medical Center, Jerusalem, Israel
| | - Polina Stepensky
- Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel.,The Bone Marrow Transplantation and Cancer Immunotherapy Department, Hadassah Ein Kerem Medical Center, Jerusalem, Israel
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9
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Kent A, Longino NV, Christians A, Davila E. Naturally Occurring Genetic Alterations in Proximal TCR Signaling and Implications for Cancer Immunotherapy. Front Immunol 2021; 12:658611. [PMID: 34012443 PMCID: PMC8126620 DOI: 10.3389/fimmu.2021.658611] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 04/06/2021] [Indexed: 11/13/2022] Open
Abstract
T cell-based immunotherapies including genetically engineered T cells, adoptive transfer of tumor-infiltrating lymphocytes, and immune checkpoint blockade highlight the impressive anti-tumor effects of T cells. These successes have provided new hope to many cancer patients with otherwise poor prognoses. However, only a fraction of patients demonstrates durable responses to these forms of therapies and many develop significant immune-mediated toxicity. These heterogeneous clinical responses suggest that underlying nuances in T cell genetics, phenotypes, and activation states likely modulate the therapeutic impact of these approaches. To better characterize known genetic variations that may impact T cell function, we 1) review the function of early T cell receptor-specific signaling mediators, 2) offer a synopsis of known mutations and genetic alterations within the associated molecules, 3) discuss the link between these mutations and human disease and 4) review therapeutic strategies under development or in clinical testing that target each of these molecules for enhancing anti-tumor T cell activity. Finally, we discuss novel engineering approaches that could be designed based on our understanding of the function of these molecules in health and disease.
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Affiliation(s)
- Andrew Kent
- Division of Medical Oncology, Department of Medicine, University of Colorado, Aurora, CO, United States
- Human Immunology and Immunotherapy Initiative, University of Colorado, Aurora, CO, United States
- University of Colorado Comprehensive Cancer Center, Aurora, CO, United States
| | - Natalie V. Longino
- Division of Medical Oncology, Department of Medicine, University of Colorado, Aurora, CO, United States
- Human Immunology and Immunotherapy Initiative, University of Colorado, Aurora, CO, United States
- University of Colorado Comprehensive Cancer Center, Aurora, CO, United States
- Department of Medicine, University of Colorado, Aurora, CO, United States
| | - Allison Christians
- Division of Medical Oncology, Department of Medicine, University of Colorado, Aurora, CO, United States
- Human Immunology and Immunotherapy Initiative, University of Colorado, Aurora, CO, United States
- University of Colorado Comprehensive Cancer Center, Aurora, CO, United States
| | - Eduardo Davila
- Division of Medical Oncology, Department of Medicine, University of Colorado, Aurora, CO, United States
- Human Immunology and Immunotherapy Initiative, University of Colorado, Aurora, CO, United States
- University of Colorado Comprehensive Cancer Center, Aurora, CO, United States
- Department of Medicine, University of Colorado, Aurora, CO, United States
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10
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Hallumi E, Shalah R, Lo WL, Corso J, Oz I, Beach D, Wittman S, Isenberg A, Sela M, Urlaub H, Weiss A, Yablonski D. Itk Promotes the Integration of TCR and CD28 Costimulation through Its Direct Substrates SLP-76 and Gads. THE JOURNAL OF IMMUNOLOGY 2021; 206:2322-2337. [PMID: 33931484 DOI: 10.4049/jimmunol.2001053] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 03/15/2021] [Indexed: 11/19/2022]
Abstract
The costimulatory receptor CD28 synergizes with the TCR to promote IL-2 production, cell survival, and proliferation; yet the obligatory interdependence of TCR and CD28 signaling is not well understood. Upon TCR stimulation, Gads, a Grb2-family adaptor, bridges the interaction of two additional adaptors, LAT and SLP-76, to form a TCR-induced effector signaling complex. SLP-76 binds the Tec-family tyrosine kinase, Itk, which phosphorylates SLP-76 Y173 and PLC-γ1 Y783. In this study, we identified TCR-inducible, Itk-mediated phosphorylation of Gads Y45 in a human T cell line and in mouse primary T cells. Y45 is found within the N-terminal SH3 domain of Gads, an evolutionarily conserved domain with no known signaling function. Gads Y45 phosphorylation depended on the interaction of Gads with SLP-76 and on the dimerization-dependent binding of Gads to phospho-LAT. We provide evidence that Itk acts through SLP-76 and Gads to promote the TCR/CD28-induced activation of the RE/AP transcriptional element from the IL-2 promoter. Two Itk-related features of SLP-76, Y173 and a proline-rich Itk SH3 binding motif on SLP-76, were dispensable for activation of NFAT but selectively required for the TCR/CD28-induced increase in cytoplasmic and nuclear c-Rel and consequent RE/AP activation. We provide evidence that unphosphorylated, monomeric Gads mediates an RE/AP-directed inhibitory activity that is mitigated upon Gads dimerization and Y45 phosphorylation. This study illuminates a new, to our knowledge, regulatory module, in which TCR-induced, Itk-mediated phosphorylation sites on SLP-76 and Gads control the transcriptional response to TCR/CD28 costimulation, thus enforcing the obligatory interdependence of the TCR and CD28 signaling pathways.
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Affiliation(s)
- Enas Hallumi
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Rose Shalah
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Wan-Lin Lo
- Rosalind Russell and Ephraim P. Engleman Arthritis Research Center, Division of Rheumatology, Department of Medicine, University of California, San Francisco, San Francisco, CA
| | - Jasmin Corso
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Ilana Oz
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Dvora Beach
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Samuel Wittman
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Amy Isenberg
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Meirav Sela
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.,Bioanalytics Research Group, Institute for Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Arthur Weiss
- Rosalind Russell and Ephraim P. Engleman Arthritis Research Center, Division of Rheumatology, Department of Medicine, University of California, San Francisco, San Francisco, CA.,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA
| | - Deborah Yablonski
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
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11
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Jaqaman K, Ditlev JA. Biomolecular condensates in membrane receptor signaling. Curr Opin Cell Biol 2021; 69:48-54. [PMID: 33461072 PMCID: PMC8058224 DOI: 10.1016/j.ceb.2020.12.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 12/09/2020] [Accepted: 12/10/2020] [Indexed: 12/17/2022]
Abstract
Clustering is a prominent feature of receptors at the plasma membrane (PM). It plays an important role in signaling. Liquid-liquid phase separation (LLPS) of proteins is emerging as a novel mechanism underlying the observed clustering. Receptors/transmembrane signaling proteins can be core components essential for LLPS (such as LAT or nephrin) or clients enriched at the phase-separated condensates (for example, at the postsynaptic density or at tight junctions). Condensate formation has been shown to regulate signaling in multiple ways, including by increasing protein binding avidity and by modulating the local biochemical environment. In moving forward, it is important to study protein LLPS at the PM of living cells, its interplay with other factors underlying receptor clustering, and its signaling and functional consequences.
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Affiliation(s)
- Khuloud Jaqaman
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Jonathon A Ditlev
- Program in Molecular Medicine, Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada.
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12
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A Novel, LAT/Lck Double Deficient T Cell Subline J.CaM1.7 for Combined Analysis of Early TCR Signaling. Cells 2021; 10:cells10020343. [PMID: 33562083 PMCID: PMC7915312 DOI: 10.3390/cells10020343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 11/21/2022] Open
Abstract
Intracellular signaling through the T cell receptor (TCR) is essential for T cell development and function. Proper TCR signaling requires the sequential activities of Lck and ZAP-70 kinases, which result in the phosphorylation of tyrosine residues located in the CD3 ITAMs and the LAT adaptor, respectively. LAT, linker for the activation of T cells, is a transmembrane adaptor protein that acts as a scaffold coupling the early signals coming from the TCR with downstream signaling pathways leading to cellular responses. The leukemic T cell line Jurkat and its derivative mutants J.CaM1.6 (Lck deficient) and J.CaM2 (LAT deficient) have been widely used to study the first signaling events upon TCR triggering. In this work, we describe the loss of LAT adaptor expression found in a subline of J.CaM1.6 cells and analyze cis-elements responsible for the LAT expression defect. This new cell subline, which we have called J.CaM1.7, can re-express LAT adaptor after Protein Kinase C (PKC) activation, which suggests that activation-induced LAT expression is not affected in this new cell subline. Contrary to J.CaM1.6 cells, re-expression of Lck in J.CaM1.7 cells was not sufficient to recover TCR-associated signals, and both LAT and Lck had to be introduced to recover activatory intracellular signals triggered after CD3 crosslinking. Overall, our work shows that the new LAT negative J.CaM1.7 cell subline could represent a new model to study the functions of the tyrosine kinase Lck and the LAT adaptor in TCR signaling, and their mutual interaction, which seems to constitute an essential early signaling event associated with the TCR/CD3 complex.
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13
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Glatzová D, Mavila H, Saija MC, Chum T, Cwiklik L, Brdička T, Cebecauer M. The role of prolines and glycine in the transmembrane domain of LAT. FEBS J 2021; 288:4039-4052. [PMID: 33458942 DOI: 10.1111/febs.15713] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 12/15/2020] [Accepted: 01/13/2021] [Indexed: 12/30/2022]
Abstract
Linker for activation in T cells (LAT) is a critical regulator of T-cell development and function. It organises signalling events at the plasma membrane. However, the mechanism, which controls LAT localisation at the plasma membrane, is not fully understood. Here, we studied the impact of helix-breaking amino acids, two prolines and one glycine, in the transmembrane segment on localisation and function of LAT. Using in silico analysis, confocal and super-resolution imaging and flow cytometry, we demonstrate that central proline residue destabilises transmembrane helix by inducing a kink. The helical structure and dynamics are further regulated by glycine and another proline residue in the luminal part of LAT transmembrane domain. Replacement of these residues with aliphatic amino acids reduces LAT dependence on palmitoylation for sorting to the plasma membrane. However, surface expression of these mutants is not sufficient to recover function of nonpalmitoylated LAT in stimulated T cells. These data indicate that geometry and dynamics of LAT transmembrane segment regulate its localisation and function in immune cells.
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Affiliation(s)
- Daniela Glatzová
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czech Republic.,Laboratory of Leukocyte Signaling, Institute of Molecule Genetics, Czech Academy of Sciences, Prague, Czech Republic.,Faculty of Science, Charles University, Prague, Czech Republic
| | - Harsha Mavila
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Maria Chiara Saija
- Department of Computational Chemistry, J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Tomáš Chum
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Lukasz Cwiklik
- Department of Computational Chemistry, J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Tomáš Brdička
- Laboratory of Leukocyte Signaling, Institute of Molecule Genetics, Czech Academy of Sciences, Prague, Czech Republic
| | - Marek Cebecauer
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czech Republic
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14
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How the T cell signaling network processes information to discriminate between self and agonist ligands. Proc Natl Acad Sci U S A 2020; 117:26020-26030. [PMID: 33020303 DOI: 10.1073/pnas.2008303117] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
T cells exhibit remarkable sensitivity and selectivity in detecting and responding to agonist peptides (p) bound to MHC molecules in a sea of self pMHC molecules. Despite much work, understanding of the underlying mechanisms of distinguishing such ligands remains incomplete. Here, we quantify T cell discriminatory capacity using channel capacity, a direct measure of the signaling network's ability to discriminate between antigen-presenting cells (APCs) displaying either self ligands or a mixture of self and agonist ligands. This metric shows how differences in information content between these two types of peptidomes are decoded by the topology and rates of kinetic proofreading signaling steps inside T cells. Using channel capacity, we constructed numerically substantiated hypotheses to explain the discriminatory role of a recently identified slow LAT Y132 phosphorylation step. Our results revealed that in addition to the number and kinetics of sequential signaling steps, a key determinant of discriminatory capability is spatial localization of a minimum number of these steps to the engaged TCR. Biochemical and imaging experiments support these findings. Our results also reveal the discriminatory role of early negative feedback and necessary amplification conferred by late positive feedback.
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15
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Chung JK, Huang WYC, Carbone CB, Nocka LM, Parikh AN, Vale RD, Groves JT. Coupled membrane lipid miscibility and phosphotyrosine-driven protein condensation phase transitions. Biophys J 2020; 120:1257-1265. [PMID: 33080222 DOI: 10.1016/j.bpj.2020.09.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/15/2020] [Accepted: 09/17/2020] [Indexed: 12/18/2022] Open
Abstract
Lipid miscibility phase separation has long been considered to be a central element of cell membrane organization. More recently, protein condensation phase transitions, into three-dimensional droplets or in two-dimensional lattices on membrane surfaces, have emerged as another important organizational principle within cells. Here, we reconstitute the linker for activation of T cells (LAT):growth-factor-receptor-bound protein 2 (Grb2):son of sevenless (SOS) protein condensation on the surface of giant unilamellar vesicles capable of undergoing lipid phase separations. Our results indicate that the assembly of the protein condensate on the membrane surface can drive lipid phase separation. This phase transition occurs isothermally and is governed by tyrosine phosphorylation on LAT. Furthermore, we observe that the induced lipid phase separation drives localization of the SOS substrate, K-Ras, into the LAT:Grb2:SOS protein condensate.
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Affiliation(s)
- Jean K Chung
- Department of Chemistry, University of California, Berkeley, Berkeley, California; The Howard Hughes Medical Institute Summer Institute, Marine Biological Laboratory, Woods Hole, Massachusetts
| | - William Y C Huang
- Department of Chemistry, University of California, Berkeley, Berkeley, California; The Howard Hughes Medical Institute Summer Institute, Marine Biological Laboratory, Woods Hole, Massachusetts
| | - Catherine B Carbone
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, California; The Howard Hughes Medical Institute Summer Institute, Marine Biological Laboratory, Woods Hole, Massachusetts
| | - Laura M Nocka
- Department of Chemistry, University of California, Berkeley, Berkeley, California
| | - Atul N Parikh
- Department of Biomedical Engineering, University of California, Davis, Davis, California
| | - Ronald D Vale
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, California; The Howard Hughes Medical Institute Summer Institute, Marine Biological Laboratory, Woods Hole, Massachusetts
| | - Jay T Groves
- Department of Chemistry, University of California, Berkeley, Berkeley, California; The Howard Hughes Medical Institute Summer Institute, Marine Biological Laboratory, Woods Hole, Massachusetts.
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16
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Tremblay MM, Ollinger T, Houtman JCD. The membrane proximal proline-rich region and correct order of C-terminal tyrosines on the adaptor protein LAT are required for TCR-mediated signaling and downstream functions. Cell Signal 2020; 76:109790. [PMID: 32979494 DOI: 10.1016/j.cellsig.2020.109790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 09/21/2020] [Accepted: 09/22/2020] [Indexed: 12/11/2022]
Abstract
The primary activating receptor for T cells is the T cell receptor (TCR), which is stimulated upon binding to an antigen/MHC complex. TCR activation results in the induction of regulated signaling pathways vital for T cell differentiation, cellular adhesion and cytokine release. A critical TCR-induced signaling protein is the adaptor protein LAT. Upon TCR stimulation, LAT is phosphorylated on conserved tyrosines, which facilitates the formation of multiprotein complexes needed for propagation of signaling pathways. Although the role of the conserved tyrosines in LAT-mediated signaling has been investigated, few studies have examined the role of larger regions of LAT in TCR-induced pathways. In this study, a sequence alignment of 97 mammalian LAT proteins was used to identify several "functional" domains on LAT. Using LAT mutants expressed in Jurkat E6.1 cells, we observed that the membrane proximal, proline-rich region of LAT and the correct order of domains containing conserved tyrosines are necessary for optimal TCR-mediated early signaling, cytokine production, and cellular adhesion. Together, these data show that LAT contains distinct regions whose presence and correct order are required for the propagation of TCR-mediated signaling pathways.
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Affiliation(s)
- Mikaela M Tremblay
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, USA
| | - Tomye Ollinger
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, USA
| | - Jon C D Houtman
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, USA.
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17
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Arbulo-Echevarria MM, Vico-Barranco I, Narbona-Sánchez I, García-Cózar F, Miazek A, Aguado E. Increased Protein Stability and Interleukin-2 Production of a LAT G131D Variant With Possible Implications for T Cell Anergy. Front Cell Dev Biol 2020; 8:561503. [PMID: 33042995 PMCID: PMC7517355 DOI: 10.3389/fcell.2020.561503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 08/13/2020] [Indexed: 11/13/2022] Open
Abstract
The adaptor LAT plays a crucial role in the transduction of signals coming from the TCR/CD3 complex. Phosphorylation of some of its tyrosines generates recruitment sites for other cytosolic signaling molecules. Tyrosine 132 in human LAT is essential for PLC-γ activation and calcium influx generation. It has been recently reported that a conserved glycine residue preceding tyrosine 132 decreases its phosphorylation kinetics, which constitutes a mechanism for ligand discrimination. Here we confirm that a LAT mutant in which glycine 131 has been substituted by an aspartate (LATG131D) increases phosphorylation of Tyr132, PLC-γ activation and calcium influx generation. Interestingly, the LATG131D mutant has a slower protein turnover while being equally sensitive to Fas-mediated protein cleavage by caspases. Moreover, J.CaM2 cells expressing LATG131D secrete greater amounts of interleukin-2 (IL-2) in response to CD3/CD28 engagement. However, despite this increased IL-2 secretion, J.CaM2 cells expressing the LATG131D mutant are more sensitive to inhibition of IL-2 production by pre-treatment with anti-CD3, which points to a possible role of this residue in the generation of anergy. Our results suggest that the increased kinetics of LAT Tyr132 phosphorylation could contribute to the establishment of T cell anergy, and thus constitutes an earliest known intracellular event responsible for the induction of peripheral tolerance.
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Affiliation(s)
| | | | | | - Francisco García-Cózar
- Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain.,Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
| | - Arkadiusz Miazek
- Department of Biochemistry and Molecular Biology, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
| | - Enrique Aguado
- Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain.,Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
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18
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Panova V, Attig J, Young GR, Stoye JP, Kassiotis G. Antibody-induced internalisation of retroviral envelope glycoproteins is a signal initiation event. PLoS Pathog 2020; 16:e1008605. [PMID: 32453763 PMCID: PMC7274472 DOI: 10.1371/journal.ppat.1008605] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 06/05/2020] [Accepted: 05/05/2020] [Indexed: 12/31/2022] Open
Abstract
As obligate parasites, viruses highjack, modify and repurpose the cellular machinery for their own replication. Viral proteins have, therefore, evolved biological functions, such as signalling potential, that alter host cell physiology in ways that are still incompletely understood. Retroviral envelope glycoproteins interact with several host proteins, extracellularly with their cellular receptor and anti-envelope antibodies, and intracellularly with proteins of the cytoskeleton or sorting, endocytosis and recirculation pathways. Here, we examined the impact of endogenous retroviral envelope glycoprotein expression and interaction with host proteins, particularly antibodies, on the cell, independently of retroviral infection. We found that in the commonly used C57BL/6 substrains of mice, where murine leukaemia virus (MLV) envelope glycoproteins are expressed by several endogenous MLV proviruses, the highest expressed MLV envelope glycoprotein is under the control of an immune-responsive cellular promoter, thus linking MLV envelope glycoprotein expression with immune activation. We further showed that antibody ligation induces extensive internalisation from the plasma membrane into endocytic compartments of MLV envelope glycoproteins, which are not normally subject to constitutive endocytosis. Importantly, antibody binding and internalisation of MLV envelope glycoproteins initiates signalling cascades in envelope-expressing murine lymphocytic cell lines, leading to cellular activation. Similar effects were observed by MLV envelope glycoprotein ligation by its cellular receptor mCAT-1, and by overexpression in human lymphocytic cells, where it required an intact tyrosine-based YXXΦ motif in the envelope glycoprotein cytoplasmic tail. Together, these results suggest that signalling potential is a general property of retroviral envelope glycoproteins and, therefore, a target for intervention. The outcome of viral infection depends on the balance between host immunity and the ability of the virus to avoid, evade or subvert it. The envelope glycoproteins of diverse viruses, including retroviruses, are displayed on the surface of virions and of infected cells and thus constitute the major target of the host antibody response. Antibody responses are elicited not only against infectious viruses we acquire during our life-history, but also against the numerous retroviral envelopes encoded by our genome and acquired during our species’ life-history. In turn, viruses have evolved ways to reduce exposure of their envelope glycoproteins to the host immune system, including constitutive endocytosis or antibody-induced internalisation. Using murine leukaemia viruses as models of infectious and endogenous retroviruses, we show that antibody binding to retroviral envelopes induces extensive internalisation of the envelope-antibody complex and initiates signalling cascades, ultimately leading to transcriptional activation of envelope glycoprotein-expressing lymphocytes. We further show that expression of endogenous retroviral envelopes is coupled to physiological lymphocyte activation, integrating them with the immune response. These findings reveal an unexpected layer of interaction between the host antibody response and retroviral envelope glycoproteins, which could be considered immune receptors.
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Affiliation(s)
- Veera Panova
- Retroviral Immunology, The Francis Crick Institute, United Kingdom
| | - Jan Attig
- Retroviral Immunology, The Francis Crick Institute, United Kingdom
| | - George R. Young
- Retrovirus-Host Interactions, The Francis Crick Institute, London, United Kingdom
| | - Jonathan P. Stoye
- Retrovirus-Host Interactions, The Francis Crick Institute, London, United Kingdom
- Department of Medicine, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - George Kassiotis
- Retroviral Immunology, The Francis Crick Institute, United Kingdom
- Department of Medicine, Faculty of Medicine, Imperial College London, London, United Kingdom
- * E-mail:
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19
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Lo WL, Shah NH, Rubin SA, Zhang W, Horkova V, Fallahee IR, Stepanek O, Zon LI, Kuriyan J, Weiss A. Slow phosphorylation of a tyrosine residue in LAT optimizes T cell ligand discrimination. Nat Immunol 2019; 20:1481-1493. [PMID: 31611699 PMCID: PMC6858552 DOI: 10.1038/s41590-019-0502-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 08/20/2019] [Indexed: 02/07/2023]
Abstract
Self-non-self discrimination is central to T cell-mediated immunity. The kinetic proofreading model can explain T cell antigen receptor (TCR) ligand discrimination; however, the rate-limiting steps have not been identified. Here, we show that tyrosine phosphorylation of the T cell adapter protein LAT at position Y132 is a critical kinetic bottleneck for ligand discrimination. LAT phosphorylation at Y132, mediated by the kinase ZAP-70, leads to the recruitment and activation of phospholipase C-γ1 (PLC-γ1), an important effector molecule for T cell activation. The slow phosphorylation of Y132, relative to other phosphosites on LAT, is governed by a preceding glycine residue (G131) but can be accelerated by substituting this glycine with aspartate or glutamate. Acceleration of Y132 phosphorylation increases the speed and magnitude of PLC-γ1 activation and enhances T cell sensitivity to weaker stimuli, including weak agonists and self-peptides. These observations suggest that the slow phosphorylation of Y132 acts as a proofreading step to facilitate T cell ligand discrimination.
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Affiliation(s)
- Wan-Lin Lo
- Division of Rheumatology, Rosalind Russell and Ephraim P. Engleman Arthritis Research Center, Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Neel H Shah
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.,Department of Chemistry, Columbia University, New York, NY, USA
| | - Sara A Rubin
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA.,Stem Cell Program and Division of Hematology/Oncology, Boston Children's Hospital and Dana-Farber Cancer Institute; Program in Immunology, Harvard Medical School, Boston, MA, USA
| | - Weiguo Zhang
- Department of Immunology, Duke University Medical Center, Durham, NC, USA
| | - Veronika Horkova
- Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Ian R Fallahee
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Ondrej Stepanek
- Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Leonard I Zon
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA.,Stem Cell Program and Division of Hematology/Oncology, Boston Children's Hospital and Dana-Farber Cancer Institute; Program in Immunology, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston Children's Hospital and Harvard University, Boston, MA, USA
| | - John Kuriyan
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.,Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Arthur Weiss
- Division of Rheumatology, Rosalind Russell and Ephraim P. Engleman Arthritis Research Center, Department of Medicine, University of California, San Francisco, San Francisco, CA, USA. .,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA, USA.
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20
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Yablonski D. Bridging the Gap: Modulatory Roles of the Grb2-Family Adaptor, Gads, in Cellular and Allergic Immune Responses. Front Immunol 2019; 10:1704. [PMID: 31402911 PMCID: PMC6669380 DOI: 10.3389/fimmu.2019.01704] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 07/08/2019] [Indexed: 01/07/2023] Open
Abstract
Antigen receptor signaling pathways are organized by adaptor proteins. Three adaptors, LAT, Gads, and SLP-76, form a heterotrimeric complex that mediates signaling by the T cell antigen receptor (TCR) and by the mast cell high affinity receptor for IgE (FcεRI). In both pathways, antigen recognition triggers tyrosine phosphorylation of LAT and SLP-76. The recruitment of SLP-76 to phospho-LAT is bridged by Gads, a Grb2 family adaptor composed of two SH3 domains flanking a central SH2 domain and an unstructured linker region. The LAT-Gads-SLP-76 complex is further incorporated into larger microclusters that mediate antigen receptor signaling. Gads is positively regulated by dimerization, which promotes its cooperative binding to LAT. Negative regulation occurs via phosphorylation or caspase-mediated cleavage of the linker region of Gads. FcεRI-mediated mast cell activation is profoundly impaired in LAT- Gads- or SLP-76-deficient mice. Unexpectedly, the thymic developmental phenotype of Gads-deficient mice is much milder than the phenotype of LAT- or SLP-76-deficient mice. This distinction suggests that Gads is not absolutely required for TCR signaling, but may modulate its sensitivity, or regulate a particular branch of the TCR signaling pathway; indeed, the phenotypic similarity of Gads- and Itk-deficient mice suggests a functional connection between Gads and Itk. Additional Gads binding partners include costimulatory proteins such as CD28 and CD6, adaptors such as Shc, ubiquitin regulatory proteins such as USP8 and AMSH, and kinases such as HPK1 and BCR-ABL, but the functional implications of these interactions are not yet fully understood. No interacting proteins or function have been ascribed to the evolutionarily conserved N-terminal SH3 of Gads. Here we explore the biochemical and functional properties of Gads, and its role in regulating allergy, T cell development and T-cell mediated immunity.
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Affiliation(s)
- Deborah Yablonski
- The Immune Cell Signaling Lab, Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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21
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Ben Khalaf N, Al-Mashoor W, Saeed A, Al-Mehatab D, Taha S, Bakhiet M, Fathallah MD. The mouse intron-nested gene, Israa, is expressed in the lymphoid organs and involved in T-cell activation and signaling. Mol Immunol 2019; 111:209-219. [PMID: 31096062 DOI: 10.1016/j.molimm.2019.04.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 03/25/2019] [Accepted: 04/13/2019] [Indexed: 10/26/2022]
Abstract
We have previously reported Israa, immune-system-released activating agent, as a novel gene nested in intron 8 of the mouse Zmiz1 gene. We have also shown that Israa encodes for a novel FYN-binding protein and might be involved in the regulation of T-cell activation. In this report, we demonstrate that Israa gene product regulates the expression of a pool of genes involved in T-cell activation and signaling. Real time PCR and GFP knock-in expression analysis showed that Israa is transcribed and expressed in the spleen mainly by CD3+CD8+ cells as well as in the thymus by CD3+ (DP and DN), CD4+SP and CD8+SP cells at different developmental stages. We also showed that Israa is downregulated in T-cells following activation of T-cell receptor. Using yeast two-hybrid analysis, we identified ELF1, a transcription factor involved in T-cell regulation, as an ISRAA-binding partner. Transcriptomic analysis of an EL4 cell line overexpressing ISRAA revealed differential expression of several genes involved in T-cell signaling, activation and development. Among these genes, Prkcb, Mib2, Fos, Ndfip2, Cxxc5, B2m, Gata3 and Cd247 were upregulated whereas Itk, Socs3, Tigit, Ifng, Il2ra and FoxJ1 were downregulated. Our findings support the existence in mouse of a novel FYN-related T-cell regulation pathway involving the product of an intron-nested gene.
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Affiliation(s)
- Noureddine Ben Khalaf
- Department of Life Sciences, Health Biotechnology Program, College of Graduates Studies, Arabian Gulf University, Manama, Bahrain
| | - Wedad Al-Mashoor
- Department of Life Sciences, Health Biotechnology Program, College of Graduates Studies, Arabian Gulf University, Manama, Bahrain
| | - Azhar Saeed
- University of Michigan Medical School, MI, USA
| | - Dalal Al-Mehatab
- Department of Life Sciences, Health Biotechnology Program, College of Graduates Studies, Arabian Gulf University, Manama, Bahrain
| | - Safa Taha
- Department of Molecular Medicine, Princess Al-Jawhara Center for Genetics and Inherited Diseases, College of Medicine and Medical Sciences, Arabian Gulf University, Bahrain
| | - Moiz Bakhiet
- Department of Molecular Medicine, Princess Al-Jawhara Center for Genetics and Inherited Diseases, College of Medicine and Medical Sciences, Arabian Gulf University, Bahrain
| | - M Dahmani Fathallah
- Department of Life Sciences, Health Biotechnology Program, College of Graduates Studies, Arabian Gulf University, Manama, Bahrain.
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22
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Tischer DK, Weiner OD. Light-based tuning of ligand half-life supports kinetic proofreading model of T cell signaling. eLife 2019; 8:42498. [PMID: 30947808 PMCID: PMC6488292 DOI: 10.7554/elife.42498] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 04/03/2019] [Indexed: 11/30/2022] Open
Abstract
T cells are thought to discriminate self from foreign peptides by converting small differences in ligand binding half-life into large changes in cell signaling. Such a kinetic proofreading model has been difficult to test directly, as existing methods of altering ligand binding half-life also change other potentially important biophysical parameters, most notably the mechanical stability of the receptor-ligand interaction. Here we develop an optogenetic approach to specifically tune the binding half-life of a chimeric antigen receptor without changing other binding parameters and provide direct evidence of kinetic proofreading in T cell signaling. This half-life discrimination is executed in the proximal signaling pathway, downstream of ZAP70 recruitment and upstream of diacylglycerol accumulation. Our methods represent a general tool for temporal and spatial control of T cell signaling and extend the reach of optogenetics to probe pathways where the individual molecular kinetics, rather than the ensemble average, gates downstream signaling.
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Affiliation(s)
- Doug K Tischer
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Orion David Weiner
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
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23
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Huang WYC, Alvarez S, Kondo Y, Lee YK, Chung JK, Lam HYM, Biswas KH, Kuriyan J, Groves JT. A molecular assembly phase transition and kinetic proofreading modulate Ras activation by SOS. Science 2019; 363:1098-1103. [PMID: 30846600 PMCID: PMC6563836 DOI: 10.1126/science.aau5721] [Citation(s) in RCA: 208] [Impact Index Per Article: 41.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 01/10/2019] [Indexed: 12/15/2022]
Abstract
The guanine nucleotide exchange factor (GEF) Son of Sevenless (SOS) is a key Ras activator that is autoinhibited in the cytosol and activates upon membrane recruitment. Autoinhibition release involves structural rearrangements of the protein at the membrane and thus introduces a delay between initial recruitment and activation. In this study, we designed a single-molecule assay to resolve the time between initial receptor-mediated membrane recruitment and the initiation of GEF activity of individual SOS molecules on microarrays of Ras-functionalized supported membranes. The rise-and-fall shape of the measured SOS activation time distribution and the long mean time scale to activation (~50 seconds) establish a basis for kinetic proofreading in the receptor-mediated activation of Ras. We further demonstrate that this kinetic proofreading is modulated by the LAT (linker for activation of T cells)-Grb2-SOS phosphotyrosine-driven phase transition at the membrane.
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Affiliation(s)
- William Y C Huang
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
| | - Steven Alvarez
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
| | - Yasushi Kondo
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
| | - Young Kwang Lee
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
| | - Jean K Chung
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
| | | | - Kabir H Biswas
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - John Kuriyan
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
- Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA
- Divisions of Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Jay T Groves
- Department of Chemistry, University of California, Berkeley, CA 94720, USA.
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
- Divisions of Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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24
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Yablonski D. Bridging the Gap: Modulatory Roles of the Grb2-Family Adaptor, Gads, in Cellular and Allergic Immune Responses. Front Immunol 2019; 10:1704. [PMID: 31402911 DOI: 10.3389/fimmu.2019.01704/full] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 07/08/2019] [Indexed: 05/22/2023] Open
Abstract
Antigen receptor signaling pathways are organized by adaptor proteins. Three adaptors, LAT, Gads, and SLP-76, form a heterotrimeric complex that mediates signaling by the T cell antigen receptor (TCR) and by the mast cell high affinity receptor for IgE (FcεRI). In both pathways, antigen recognition triggers tyrosine phosphorylation of LAT and SLP-76. The recruitment of SLP-76 to phospho-LAT is bridged by Gads, a Grb2 family adaptor composed of two SH3 domains flanking a central SH2 domain and an unstructured linker region. The LAT-Gads-SLP-76 complex is further incorporated into larger microclusters that mediate antigen receptor signaling. Gads is positively regulated by dimerization, which promotes its cooperative binding to LAT. Negative regulation occurs via phosphorylation or caspase-mediated cleavage of the linker region of Gads. FcεRI-mediated mast cell activation is profoundly impaired in LAT- Gads- or SLP-76-deficient mice. Unexpectedly, the thymic developmental phenotype of Gads-deficient mice is much milder than the phenotype of LAT- or SLP-76-deficient mice. This distinction suggests that Gads is not absolutely required for TCR signaling, but may modulate its sensitivity, or regulate a particular branch of the TCR signaling pathway; indeed, the phenotypic similarity of Gads- and Itk-deficient mice suggests a functional connection between Gads and Itk. Additional Gads binding partners include costimulatory proteins such as CD28 and CD6, adaptors such as Shc, ubiquitin regulatory proteins such as USP8 and AMSH, and kinases such as HPK1 and BCR-ABL, but the functional implications of these interactions are not yet fully understood. No interacting proteins or function have been ascribed to the evolutionarily conserved N-terminal SH3 of Gads. Here we explore the biochemical and functional properties of Gads, and its role in regulating allergy, T cell development and T-cell mediated immunity.
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Affiliation(s)
- Deborah Yablonski
- The Immune Cell Signaling Lab, Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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25
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Martín-Cófreces NB, Vicente-Manzanares M, Sánchez-Madrid F. Adhesive Interactions Delineate the Topography of the Immune Synapse. Front Cell Dev Biol 2018; 6:149. [PMID: 30425987 PMCID: PMC6218456 DOI: 10.3389/fcell.2018.00149] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 10/11/2018] [Indexed: 01/04/2023] Open
Abstract
T cells form adhesive contacts with antigen-presenting cells (APCs) as part of the normal surveillance process that occurs in lymph nodes and other tissues. Most of these adhesive interactions are formed by integrins that interact with ligands expressed on the surface of the APC. The interactive strength of integrins depends on their degree of membrane proximity as well as intracellular signals that dictate the conformation of the integrin. Integrins appear in different conformations that endow them with different affinities for their ligand(s). Integrin conformation and thus adhesive strength between the T cell and the APC is tuned by intracellular signals that are turned on by ligation of the T cell receptor (TCR) and chemokine receptors. During the different stages of the process, integrins, the TCR and chemokine receptors may be interconnected by the actin cytoskeleton underneath the plasma membrane, forming a chemical and physical network that facilitates the spatiotemporal dynamics, positioning, and function of these receptors and supports cell-cell adhesion during T cell activation, allowing it to perform its effector function.
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Affiliation(s)
- Noa Beatriz Martín-Cófreces
- Servicio de Inmunología, Instituto de Investigación Sanitaria Princesa (IP), Hospital Universitario de la Princesa, Universidad Autónoma de Madrid, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - Miguel Vicente-Manzanares
- Centro de Investigación del Cáncer-Instituto de Biología Molecular y Celular del Cáncer, CIC-IBMCC (CSIC-Universidad de Salamanca), Salamanca, Spain
| | - Francisco Sánchez-Madrid
- Servicio de Inmunología, Instituto de Investigación Sanitaria Princesa (IP), Hospital Universitario de la Princesa, Universidad Autónoma de Madrid, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
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26
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Arbulo-Echevarria MM, Narbona-Sánchez I, Fernandez-Ponce CM, Vico-Barranco I, Rueda-Ygueravide MD, Dustin ML, Miazek A, Duran-Ruiz MC, García-Cózar F, Aguado E. A Stretch of Negatively Charged Amino Acids of Linker for Activation of T-Cell Adaptor Has a Dual Role in T-Cell Antigen Receptor Intracellular Signaling. Front Immunol 2018; 9:115. [PMID: 29456532 PMCID: PMC5801411 DOI: 10.3389/fimmu.2018.00115] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 01/15/2018] [Indexed: 11/13/2022] Open
Abstract
The adaptor protein linker for activation of T cells (LAT) has an essential role transducing activatory intracellular signals coming from the TCR/CD3 complex. Previous reports have shown that upon T-cell activation, LAT interacts with the tyrosine kinase Lck, leading to the inhibition of its kinase activity. LAT-Lck interaction seemed to depend on a stretch of negatively charged amino acids in LAT. Here, we have substituted this segment of LAT between amino acids 113 and 126 with a non-charged segment and expressed the mutant LAT (LAT-NIL) in J.CaM2 cells in order to analyze TCR signaling. Substitution of this segment in LAT prevented the activation-induced interaction with Lck. Moreover, cells expressing this mutant form of LAT showed a statistically significant increase of proximal intracellular signals such as phosphorylation of LAT in tyrosine residues 171 and 191, and also enhanced ZAP70 phosphorylation approaching borderline statistical significance (p = 0.051). Nevertheless, downstream signals such as Ca2+ influx or MAPK pathways were partially inhibited. Overall, our data reveal that LAT-Lck interaction constitutes a key element regulating proximal intracellular signals coming from the TCR/CD3 complex.
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Affiliation(s)
- Mikel M Arbulo-Echevarria
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
| | - Isaac Narbona-Sánchez
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
| | - Cecilia M Fernandez-Ponce
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
| | - Inmaculada Vico-Barranco
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
| | | | - Michael L Dustin
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, The Kennedy Institute of Rheumatology, The University of Oxford, Headington, United Kingdom
| | - Arkadiusz Miazek
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland
| | - Mª Carmen Duran-Ruiz
- Department of Biomedicine, Biotechnology and Public Health (Biochemistry), University of Cádiz, Cádiz, Spain.,Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain
| | - Francisco García-Cózar
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain.,Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain
| | - Enrique Aguado
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain.,Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain
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27
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Structure function relations in PDZ-domain-containing proteins: Implications for protein networks in cellular signalling. J Biosci 2017. [DOI: 10.1007/s12038-017-9727-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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28
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Sukenik S, Frushicheva MP, Waknin-Lellouche C, Hallumi E, Ifrach T, Shalah R, Beach D, Avidan R, Oz I, Libman E, Aronheim A, Lewinson O, Yablonski D. Dimerization of the adaptor Gads facilitates antigen receptor signaling by promoting the cooperative binding of Gads to the adaptor LAT. Sci Signal 2017; 10:10/498/eaal1482. [PMID: 28951535 DOI: 10.1126/scisignal.aal1482] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The accurate assembly of signalosomes centered on the adaptor protein LAT (linker of activated T cells) is required for antigen receptor signaling in T cells and mast cells. During signalosome assembly, members of the growth factor receptor-bound protein 2 (Grb2) family of cytosolic adaptor proteins bind cooperatively to LAT through interactions with its phosphorylated tyrosine (pTyr) residues. We demonstrated the Src homology 2 (SH2) domain-mediated dimerization of the Grb2 family member, Grb2-related adaptor downstream of Shc (Gads). Gads dimerization was mediated by an SH2 domain interface, which is distinct from the pTyr binding pocket and which promoted cooperative, preferential binding of paired Gads to LAT. This SH2 domain-intrinsic mechanism of cooperativity, which we quantified by mathematical modeling, enabled Gads to discriminate between dually and singly phosphorylated LAT molecules. Mutational inactivation of the dimerization interface reduced cooperativity and abrogated Gads signaling in T cells and mast cells. The dimerization-dependent, cooperative binding of Gads to LAT may increase antigen receptor sensitivity by reducing signalosome formation at incompletely phosphorylated LAT molecules, thereby prioritizing the formation of complete signalosomes.
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Affiliation(s)
- Sigalit Sukenik
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 3525433, Israel
| | - Maria P Frushicheva
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Cecilia Waknin-Lellouche
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 3525433, Israel
| | - Enas Hallumi
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 3525433, Israel
| | - Talia Ifrach
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 3525433, Israel
| | - Rose Shalah
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 3525433, Israel
| | - Dvora Beach
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 3525433, Israel
| | - Reuven Avidan
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 3525433, Israel
| | - Ilana Oz
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 3525433, Israel
| | - Evgeny Libman
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 3525433, Israel
| | - Ami Aronheim
- Department of Cell Biology and Cancer Science, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 3525433, Israel
| | - Oded Lewinson
- Department of Biochemistry, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 3525433, Israel
| | - Deborah Yablonski
- Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 3525433, Israel.
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LFA-1 activates focal adhesion kinases FAK1/PYK2 to generate LAT-GRB2-SKAP1 complexes that terminate T-cell conjugate formation. Nat Commun 2017; 8:16001. [PMID: 28699640 PMCID: PMC5510181 DOI: 10.1038/ncomms16001] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 05/23/2017] [Indexed: 01/27/2023] Open
Abstract
Lymphocyte function-associated antigen 1 (LFA-1) affinity and avidity changes have been assumed to mediate adhesion to intercellular adhesion molecule-1 for T-cell conjugation to dendritic cells (DC). Although the T-cell receptor (TCR) and LFA-1 can generate intracellular signals, the immune cell adaptor protein linker for the activation of T cells (LAT) couples the TCR to downstream events. Here, we show that LFA-1 can mediate both adhesion and de-adhesion, dependent on receptor clustering. Although increased affinity mediates adhesion, LFA-1 cross-linking induced the association and activation of the protein-tyrosine kinases FAK1/PYK1 that phosphorylated LAT selectively on a single Y-171 site for the binding to adaptor complex GRB-2-SKAP1. LAT-GRB2-SKAP1 complexes were distinct from canonical LAT-GADs-SLP-76 complexes. LFA-1 cross-linking increased the presence of LAT-GRB2-SKAP1 complexes relative to LAT-GADs-SLP-76 complexes. LFA-1-FAK1 decreased T-cell-dendritic cell (DC) dwell times dependent on LAT-Y171, leading to reduced DO11.10 T cell binding to DCs and proliferation to OVA peptide. Overall, our findings outline a new model for LFA-1 in which the integrin can mediate both adhesion and de-adhesion events dependent on receptor cross-linking. The T-cell integrin LFA-1 binds ICAM-1 on antigen presenting cells to affect TCR-MHC interactions. Here the authors show detailed mechanics of how LFA-1 ligation affects T-cell conjugation to dendritic cells to regulate adhesion and de-adhesion of these cells in the context of antigen presentation.
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Abstract
Biochemical reconstitution has served as an important tool for understanding the mechanisms of many cellular processes including DNA replication, transcription, translation, vesicle trafficking, and ubiquitin-mediated proteolysis. Here, we demonstrate that biochemical reconstitution can be applied to studying a complex signaling pathway involving as many as 12 proteins or protein complexes acting at the surface of model membranes. We show that a temporal sequence of events in activated T cells beginning with phosphorylation of the T cell receptor and culminating in the activation of actin polymerization can be replicated in vitro. Our reconstitution demonstrates the sufficiency of these proteins in producing many of the complex behaviors observed during T cell activation. The ability to manipulate all of the components, measure reaction rates, and observe molecular behaviors, including at single molecule resolution, has enabled us to gain insight into some of the important biochemical features of this signaling pathway such as microcluster formation. The same system could be adapted to study other membrane-proximal signaling pathways, including growth factor receptors, death receptors, and Eph receptors.
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Affiliation(s)
- Xiaolei Su
- Marine Biological Laboratory, The HHMI Summer Institute, Woods Hole, MA, 02543, USA
- Department of Cellular and Molecular Pharmacology and Howard Hughes Medical Institute, University of California, San Francisco, CA, 94158, USA
| | - Jonathon A Ditlev
- Marine Biological Laboratory, The HHMI Summer Institute, Woods Hole, MA, 02543, USA
- Department of Biophysics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Michael K Rosen
- Marine Biological Laboratory, The HHMI Summer Institute, Woods Hole, MA, 02543, USA
- Department of Biophysics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Ronald D Vale
- Marine Biological Laboratory, The HHMI Summer Institute, Woods Hole, MA, 02543, USA.
- Department of Cellular and Molecular Pharmacology and Howard Hughes Medical Institute, University of California, San Francisco, CA, 94158, USA.
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31
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Phosphotyrosine-mediated LAT assembly on membranes drives kinetic bifurcation in recruitment dynamics of the Ras activator SOS. Proc Natl Acad Sci U S A 2016; 113:8218-23. [PMID: 27370798 DOI: 10.1073/pnas.1602602113] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The assembly of cell surface receptors with downstream signaling molecules is a commonly occurring theme in multiple signaling systems. However, little is known about how these assemblies modulate reaction kinetics and the ultimate propagation of signals. Here, we reconstitute phosphotyrosine-mediated assembly of extended linker for the activation of T cells (LAT):growth factor receptor-bound protein 2 (Grb2):Son of Sevenless (SOS) networks, derived from the T-cell receptor signaling system, on supported membranes. Single-molecule dwell time distributions reveal two, well-differentiated kinetic species for both Grb2 and SOS on the LAT assemblies. The majority fraction of membrane-recruited Grb2 and SOS both exhibit fast kinetics and single exponential dwell time distributions, with average dwell times of hundreds of milliseconds. The minor fraction exhibits much slower kinetics, extending the dwell times to tens of seconds. Considering this result in the context of the multistep process by which the Ras GEF (guanine nucleotide exchange factor) activity of SOS is activated indicates that kinetic stabilization from the LAT assembly may be important. This kinetic proofreading effect would additionally serve as a stochastic noise filter by reducing the relative probability of spontaneous SOS activation in the absence of receptor triggering. The generality of receptor-mediated assembly suggests that such effects may play a role in multiple receptor proximal signaling processes.
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32
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Keller B, Zaidman I, Yousefi OS, Hershkovitz D, Stein J, Unger S, Schachtrup K, Sigvardsson M, Kuperman AA, Shaag A, Schamel WW, Elpeleg O, Warnatz K, Stepensky P. Early onset combined immunodeficiency and autoimmunity in patients with loss-of-function mutation in LAT. J Exp Med 2016; 213:1185-99. [PMID: 27242165 PMCID: PMC4925012 DOI: 10.1084/jem.20151110] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 05/04/2016] [Indexed: 12/13/2022] Open
Abstract
Keller et al. describe for the first time human LAT deficiency, which causes severe immune dysregulation with autoimmunity, lymphoproliferation, and progressive immunodeficiency. The adapter protein linker for activation of T cells (LAT) is a critical signaling hub connecting T cell antigen receptor triggering to downstream T cell responses. In this study, we describe the first kindred with defective LAT signaling caused by a homozygous mutation in exon 5, leading to a premature stop codon deleting most of the cytoplasmic tail of LAT, including the critical tyrosine residues for signal propagation. The three patients presented from early childhood with combined immunodeficiency and severe autoimmune disease. Unlike in the mouse counterpart, reduced numbers of T cells were present in the patients. Despite the reported nonredundant role of LAT in Ca2+ mobilization, residual T cells were able to induce Ca2+ influx and nuclear factor (NF) κB signaling, whereas extracellular signal-regulated kinase (ERK) signaling was completely abolished. This is the first report of a LAT-related disease in humans, manifesting by a progressive combined immune deficiency with severe autoimmune disease.
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Affiliation(s)
- Baerbel Keller
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany
| | - Irina Zaidman
- Department of Pediatric Hematology Oncology, Ruth Rappaport Children's Hospital, Rambam Health Care Campus, Haifa 3109601, Israel
| | - O Sascha Yousefi
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany Department of Molecular Immunology, Faculty of Biology, BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany Spemann Graduate School of Biology and Medicine (SGBM), Albert Ludwigs University Freiburg, 79104 Freiburg, Germany
| | - Dov Hershkovitz
- Department of Pathology, Rambam Health Care Campus, Haifa 3109601, Israel
| | - Jerry Stein
- Department of Pediatric Hematology Oncology and Bone Marrow Transplantation Unit, Schneider Children's Medical Center of Israel, Petah-Tikva 49202, Israel
| | - Susanne Unger
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany
| | - Kristina Schachtrup
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany
| | - Mikael Sigvardsson
- Department of Clinical and Experimental Medicine, Experimental Hematopoiesis Unit, Faculty of Health Sciences, Linköping University, 581 85 Linköping, Sweden
| | - Amir A Kuperman
- Blood Coagulation Service and Pediatric Hematology Clinic, Galilee Medical Center, Nahariya 22100, Israel Faculty of Medicine in the Galilee, Bar-Ilan University, Safed 5290002, Israel
| | - Avraham Shaag
- Monique and Jacques Roboh Department of Genetic Research, Hadassah Medical Center, Hebrew University, Jerusalem 91120, Israel
| | - Wolfgang W Schamel
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany Department of Molecular Immunology, Faculty of Biology, BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Orly Elpeleg
- Monique and Jacques Roboh Department of Genetic Research, Hadassah Medical Center, Hebrew University, Jerusalem 91120, Israel
| | - Klaus Warnatz
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany
| | - Polina Stepensky
- Monique and Jacques Roboh Department of Genetic Research, Hadassah Medical Center, Hebrew University, Jerusalem 91120, Israel Department of Pediatric Hematology-Oncology and Bone Marrow Transplantation, Hadassah Medical Center, Hebrew University, Jerusalem 91120, Israel
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Arbulo-Echevarria MM, Muñoz-Miranda JP, Caballero-García A, Poveda-Díaz JL, Fernández-Ponce C, Durán-Ruiz MC, Miazek A, García-Cózar F, Aguado E. Non-T cell activation linker (NTAL) proteolytic cleavage as a terminator of activatory intracellular signals. J Leukoc Biol 2016; 100:351-60. [PMID: 26830332 DOI: 10.1189/jlb.2a0715-318r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 01/21/2016] [Indexed: 12/13/2022] Open
Abstract
Non-T cell activation linker is an adaptor protein that is tyrosine phosphorylated upon cross-linking of immune receptors expressed on B lymphocytes, NK cells, macrophages, basophils, or mast cells, allowing the recruitment of cytosolic mediators for downstream signaling pathways. Fas receptor acts mainly as a death receptor, and when cross-linked with Fas ligand, many proteins are proteolytically cleaved, including several signaling molecules in T and B cells. Fas receptor triggering also interferes with TCR intracellular signals, probably by means of proteolytic cleavage of several adaptor proteins. We have previously found that the adaptor linker for activation of T cells, evolutionarily related to non-T cell activation linker, is cleaved upon proapoptotic stimuli in T lymphocytes and thymocytes, in a tyrosine phosphorylation-dependent fashion. Here, we describe non-T cell activation linker proteolytic cleavage triggered in human B cells and monocytes by Fas cross-linking and staurosporine treatment. Non-T cell activation linker is cleaved, producing an N-terminal fragment of ∼22 kDa, and such cleavage is abrogated in the presence of caspase 8/granzyme B and caspase 3 inhibitors. Moreover, we have identified an aspartic acid residue at which non-T cell activation linker is cleaved, which similar to linker for activation of T cells, this aspartic acid residue is located close to tyrosine and serine residues, suggesting an interdependence of phosphorylation and proteolytic cleavage. Consistently, induction of non-T cell activation linker phosphorylation by pervanadate inhibits its cleavage. Interestingly, the truncated isoform of non-T cell activation linker, generated after cleavage, has a decreased signaling ability when compared with the full-length molecule. Altogether, our results suggest that cleavage of transmembrane adaptors constitutes a general mechanism for signal termination of immune receptors.
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Affiliation(s)
- Mikel M Arbulo-Echevarria
- Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cádiz, Spain
| | - Juan Pedro Muñoz-Miranda
- Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cádiz, Spain
| | - Andrés Caballero-García
- Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cádiz, Spain
| | - José L Poveda-Díaz
- Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cádiz, Spain
| | - Cecilia Fernández-Ponce
- Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cádiz, Spain
| | - M Carmen Durán-Ruiz
- Department of Biomedicine, Biotechnology and Public Health (Biochemistry), University of Cádiz, Cádiz, Spain
| | - Arkadiusz Miazek
- Department of Biochemistry, Pharmacology and Toxicology, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
| | - Francisco García-Cózar
- Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cádiz, Spain
| | - Enrique Aguado
- Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cádiz, Spain,
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Martin-Blanco N, Jiménez Teja D, Bretones G, Borroto A, Caraballo M, Screpanti I, León J, Alarcón B, Canelles M. CD3ε recruits Numb to promote TCR degradation. Int Immunol 2015; 28:127-37. [PMID: 26507128 DOI: 10.1093/intimm/dxv060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 10/15/2015] [Indexed: 01/05/2023] Open
Abstract
Modulation of TCR signaling upon ligand binding is achieved by changes in the equilibrium between TCR degradation, recycling and synthesis; surprisingly, the molecular mechanism of such an important process is not fully understood. Here, we describe the role of a new player in the mediation of TCR degradation: the endocytic adaptor Numb. Our data show that Numb inhibition leads to abnormal intracellular distribution and defective TCR degradation in mature T lymphocytes. In addition, we find that Numb simultaneously binds to both Cbl and a site within CD3ε that overlaps with the Nck binding site. As a result, Cbl couples specifically to the CD3ε chain to mediate TCR degradation. The present study unveils a novel role of Numb that lies at the heart of TCR signaling initiation and termination.
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Affiliation(s)
- Nadia Martin-Blanco
- Instituto de Parasitología y Biomedicina, CSIC, P. T. Ciencias de la Salud, 18100 Granada, Spain Centro de Biología Molecular Severo Ochoa, CSIC, Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Daniel Jiménez Teja
- Instituto de Parasitología y Biomedicina, CSIC, P. T. Ciencias de la Salud, 18100 Granada, Spain
| | - Gabriel Bretones
- Departamento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria-CSIC-SODERCAN, Santander, Spain
| | - Aldo Borroto
- Centro de Biología Molecular Severo Ochoa, CSIC, Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Michael Caraballo
- Instituto de Parasitología y Biomedicina, CSIC, P. T. Ciencias de la Salud, 18100 Granada, Spain
| | - Isabella Screpanti
- Laboratory of Molecular Pathology, Department of Experimental Medicine, Sapienza University of Rome, Viale Regina Elena, 324, 00161 Rome, Italy
| | - Javier León
- Departamento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria-CSIC-SODERCAN, Santander, Spain
| | - Balbino Alarcón
- Centro de Biología Molecular Severo Ochoa, CSIC, Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Matilde Canelles
- Instituto de Parasitología y Biomedicina, CSIC, P. T. Ciencias de la Salud, 18100 Granada, Spain
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Balagopalan L, Kortum RL, Coussens NP, Barr VA, Samelson LE. The linker for activation of T cells (LAT) signaling hub: from signaling complexes to microclusters. J Biol Chem 2015; 290:26422-9. [PMID: 26354432 DOI: 10.1074/jbc.r115.665869] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Since the cloning of the critical adapter, LAT (linker for activation of T cells), more than 15 years ago, a combination of multiple scientific approaches and techniques continues to provide valuable insights into the formation, composition, regulation, dynamics, and function of LAT-based signaling complexes. In this review, we will summarize current views on the assembly of signaling complexes nucleated by LAT. LAT forms numerous interactions with other signaling molecules, leading to cooperativity in the system. Furthermore, oligomerization of LAT by adapter complexes enhances intracellular signaling and is physiologically relevant. These results will be related to data from super-resolution microscopy studies that have revealed the smallest LAT-based signaling units and nanostructure.
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Affiliation(s)
- Lakshmi Balagopalan
- From the Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892-4256
| | - Robert L Kortum
- the Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, and
| | - Nathan P Coussens
- the Division of Pre-Clinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20850
| | - Valarie A Barr
- From the Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892-4256
| | - Lawrence E Samelson
- From the Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892-4256,
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Spleen-specific isoforms of Pax5 and Ataxin-7 as potential proteomic markers of lymphoma-affected spleen. Mol Cell Biochem 2015; 402:181-91. [PMID: 25573326 DOI: 10.1007/s11010-014-2325-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 12/23/2014] [Indexed: 02/06/2023]
Abstract
The splenomegaly, enlargement of spleen, has been observed in several diseases. It has been intended to evaluate histochemical alterations, spleen-specific enzymatic and proteomic markers during splenomegaly, and lympho-proliferative disorders from spleen of mice bearing Dalton's lymphoma. The higher expression of c-fos, c-jun, and MAPK testifies proliferation of lymphocytes. The lower expression of Pax5, higher expression of CD3, and the presence of additional form of Zap-70 suggest hypertrophy of follicles and splenomegaly influenced by weak B-cell receptor-mediated signaling, but activated T-cell receptor-mediated signaling. Simultaneously, lower levels of SOD, NDR2, and MIB2 and higher expression levels of Ataxin-7 and LDH also suggest impact of stress either as a cause or effect of cell proliferation. Spleen-specific isoform of Pax5, NDR2, MIB2, and Ataxin-7 can be considered as spleen-specific unique molecular markers for the evaluation of splenomegaly and lympho-proliferative disorders.
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Modulation of TCR responsiveness by the Grb2-family adaptor, Gads. Cell Signal 2014; 27:125-34. [PMID: 25452106 DOI: 10.1016/j.cellsig.2014.10.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 10/16/2014] [Indexed: 12/11/2022]
Abstract
T cell antigen receptor (TCR) signaling depends on three interacting adaptor proteins: SLP-76, Gads, and LAT. Their mechanisms of signaling have been extensively explored, with the aid of fortuitously isolated LAT- and SLP-76-deficient T cell lines, but no such tools were available for Gads, a Grb2-family adaptor that bridges the TCR-inducible interaction between SLP-76 and LAT. TALEN-directed genome editing was applied to disrupt the first coding exon of human Gads in the Jurkat T cell line. Gads was dispensable for TCR-induced phosphorylation of SLP-76, but was a dose-dependent amplifier of TCR-induced CD69 expression. Gads conferred responsiveness to weak TCR stimuli, leading to PLC-γ1 phosphorylation and calcium flux. TALEN-derived, Gads-deficient T cell lines provide a uniquely tractable genetic platform for exploring its regulatory features, such as Gads phosphorylation at T262, which we observed by mass spectrometry. Upon mutation of this site, TCR responsiveness and sensitivity to weak TCR stimuli were increased. This study demonstrates the feasibility of TALEN-based reverse genetics in Jurkat T cells, while enriching our understanding of Gads as a regulated modulator of TCR sensitivity.
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38
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Sheng W, Liu C, Fu R, Wang H, Qu W, Ruan E, Wang G, Liu H, Wu Y, Song J, Xing L, Guan J, Li L, Liu H, Shao Z. Abnormalities of quantities and functions of linker for activations of T cells in severe aplastic anemia. Eur J Haematol 2014; 93:214-23. [PMID: 24673455 DOI: 10.1111/ejh.12327] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/17/2014] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Severe aplastic anemia (SAA) is a rare immune-regulated disease characterized by severe pancytopenia and bone marrow failure, caused by destruction of hematopoietic cells by the activated T lymphocytes. Linker for activation of T cells (LAT), a transmembrane adaptor protein, plays a key role in T-cell and mast cell functions. However, it remains unclear how LAT may change in patients with SAA. This study aims at understanding the role of lymphocyte LAT in SAA. METHODS The expression of LAT, related signaling molecules, and T-cell effector molecules was determined by flow cytometry. LAT mRNA was evaluated by quantitative real-time PCR. Cytokine production by cultured T cells was determined by ELISA. RESULTS Patients with SAA had an increased levels of LAT and both total phosphorylated LAT and of the related molecule (ZAP-70) in circulating T cells compared with normal controls. In patients with SAA, the expression of LAT was positively associated with the expression of perforin and granzyme B in CD8(+) T cells. Inhibition of LAT expression in T cells from patients with SAA decreased the activation of the CD4(+) and CD8(+) T-cell subsets. Overexpression of LAT in T cells from normal controls increased the activation of CD4(+) and CD8(+) T-cell subsets with increased apoptosis of K562 cells in coculture. CONCLUSIONS Our findings demonstrate that dysregulation of LAT expression and activation may contribute to over-function of T cells, imbalance of Th1/Th2 subsets and thus lead to hematopoiesis failure in SAA. Immunosuppressive therapy dramatically reduced the expression of LAT making it an attractive therapeutic target in SAA.
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Affiliation(s)
- Weiwei Sheng
- The Department of Hematology, The General Hospital of Tianjin Medical University, Tianjin, China
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Cruz-Orcutt N, Vacaflores A, Connolly SF, Bunnell SC, Houtman JCD. Activated PLC-γ1 is catalytically induced at LAT but activated PLC-γ1 is localized at both LAT- and TCR-containing complexes. Cell Signal 2014; 26:797-805. [PMID: 24412752 DOI: 10.1016/j.cellsig.2013.12.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 12/31/2013] [Indexed: 12/27/2022]
Abstract
Phospholipase C-γ1 (PLC-γ1) is a key regulator of T cell receptor (TCR)-induced signaling. Activation of the TCR enhances PLC-γ1 enzymatic function, resulting in calcium influx and the activation of PKC family members and RasGRP. The current model is that phosphorylation of LAT tyrosine 132 facilitates the recruitment of PLC-γ1, leading to its activation and function at the LAT complex. In this study, we examined the phosphorylation kinetics of LAT and PLC-γ1 and the cellular localization of activated PLC-γ1. We observed that commencement of the phosphorylation of LAT tyrosine 132 and PLC-γ1 tyrosine 783 occurred simultaneously, supporting the current model. However, once begun, PLC-γ1 activation occurred more rapidly than LAT tyrosine 132. The association of LAT and PLC-γ1 was more transient than the interaction of LAT and Grb2 and a pool of activated PLC-γ1 translocated away from LAT to cellular structures containing the TCR. These studies demonstrate that LAT and PLC-γ1 form transient interactions that catalyze the activation of PLC-γ1, but that activated PLC-γ1 resides in both LAT and TCR clusters. Together, this work highlights that our current model is incomplete and the activation and function of PLC-γ1 in T cells is highly complex.
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Affiliation(s)
- Noemi Cruz-Orcutt
- Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States
| | - Aldo Vacaflores
- Interdisciplinary Graduate Program in Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States
| | - Sean F Connolly
- Interdisciplinary Graduate Program in Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States
| | - Stephen C Bunnell
- Program in Immunology, Sackler School of Graduate Biomedical Sciences, Boston, MA 02111, United States; Department of Pathology, Tufts University School of Medicine, Boston, MA 02111, United States
| | - Jon C D Houtman
- Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States; Interdisciplinary Graduate Program in Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States.
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Mukherjee S, Rigaud S, Seok SC, Fu G, Prochenka A, Dworkin M, Gascoigne NRJ, Vieland VJ, Sauer K, Das J. In silico modeling of Itk activation kinetics in thymocytes suggests competing positive and negative IP4 mediated feedbacks increase robustness. PLoS One 2013; 8:e73937. [PMID: 24066087 PMCID: PMC3774804 DOI: 10.1371/journal.pone.0073937] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 07/25/2013] [Indexed: 12/29/2022] Open
Abstract
The inositol-phosphate messenger inositol(1,3,4,5)tetrakisphosphate (IP4) is essential for thymocyte positive selection by regulating plasma-membrane association of the protein tyrosine kinase Itk downstream of the T cell receptor (TCR). IP4 can act as a soluble analog of the phosphoinositide 3-kinase (PI3K) membrane lipid product phosphatidylinositol(3,4,5)trisphosphate (PIP3). PIP3 recruits signaling proteins such as Itk to cellular membranes by binding to PH and other domains. In thymocytes, low-dose IP4 binding to the Itk PH domain surprisingly promoted and high-dose IP4 inhibited PIP3 binding of Itk PH domains. However, the mechanisms that underlie the regulation of membrane recruitment of Itk by IP4 and PIP3 remain unclear. The distinct Itk PH domain ability to oligomerize is consistent with a cooperative-allosteric mode of IP4 action. However, other possibilities cannot be ruled out due to difficulties in quantitatively measuring the interactions between Itk, IP4 and PIP3, and in generating non-oligomerizing Itk PH domain mutants. This has hindered a full mechanistic understanding of how IP4 controls Itk function. By combining experimentally measured kinetics of PLCγ1 phosphorylation by Itk with in silico modeling of multiple Itk signaling circuits and a maximum entropy (MaxEnt) based computational approach, we show that those in silico models which are most robust against variations of protein and lipid expression levels and kinetic rates at the single cell level share a cooperative-allosteric mode of Itk regulation by IP4 involving oligomeric Itk PH domains at the plasma membrane. This identifies MaxEnt as an excellent tool for quantifying robustness for complex TCR signaling circuits and provides testable predictions to further elucidate a controversial mechanism of PIP3 signaling.
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Affiliation(s)
- Sayak Mukherjee
- Battelle Center for Mathematical Medicine, The Research Institute at the Nationwide Children’s Hospital, Columbus, Ohio, United States of America
| | - Stephanie Rigaud
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California, United States of America
| | - Sang-Cheol Seok
- Battelle Center for Mathematical Medicine, The Research Institute at the Nationwide Children’s Hospital, Columbus, Ohio, United States of America
| | - Guo Fu
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California, United States of America
| | - Agnieszka Prochenka
- Battelle Center for Mathematical Medicine, The Research Institute at the Nationwide Children’s Hospital, Columbus, Ohio, United States of America
- Institute of Computer Science, Polish Academy of Sciences, Warsaw, Poland
| | - Michael Dworkin
- Battelle Center for Mathematical Medicine, The Research Institute at the Nationwide Children’s Hospital, Columbus, Ohio, United States of America
- Department of Mathematics, The Ohio State University, Columbus, Ohio, United States of America
| | - Nicholas R. J. Gascoigne
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California, United States of America
| | - Veronica J. Vieland
- Battelle Center for Mathematical Medicine, The Research Institute at the Nationwide Children’s Hospital, Columbus, Ohio, United States of America
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
- Department of Statistics, The Ohio State University, Columbus, Ohio, United States of America
| | - Karsten Sauer
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California, United States of America
- * E-mail: (KS); (JD)
| | - Jayajit Das
- Battelle Center for Mathematical Medicine, The Research Institute at the Nationwide Children’s Hospital, Columbus, Ohio, United States of America
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
- Department of Physics, The Ohio State University, Columbus, Ohio, United States of America
- Biophysics Graduate Program, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail: (KS); (JD)
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41
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Jun JE, Rubio I, Roose JP. Regulation of ras exchange factors and cellular localization of ras activation by lipid messengers in T cells. Front Immunol 2013; 4:239. [PMID: 24027568 PMCID: PMC3762125 DOI: 10.3389/fimmu.2013.00239] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Accepted: 08/02/2013] [Indexed: 11/17/2022] Open
Abstract
The Ras-MAPK signaling pathway is highly conserved throughout evolution and is activated downstream of a wide range of receptor stimuli. Ras guanine nucleotide exchange factors (RasGEFs) catalyze GTP loading of Ras and play a pivotal role in regulating receptor-ligand induced Ras activity. In T cells, three families of functionally important RasGEFs are expressed: RasGRF, RasGRP, and Son of Sevenless (SOS)-family GEFs. Early on it was recognized that Ras activation is critical for T cell development and that the RasGEFs play an important role herein. More recent work has revealed that nuances in Ras activation appear to significantly impact T cell development and selection. These nuances include distinct biochemical patterns of analog versus digital Ras activation, differences in cellular localization of Ras activation, and intricate interplays between the RasGEFs during distinct T cell developmental stages as revealed by various new mouse models. In many instances, the exact nature of these nuances in Ras activation or how these may result from fine-tuning of the RasGEFs is not understood. One large group of biomolecules critically involved in the control of RasGEFs functions are lipid second messengers. Multiple, yet distinct lipid products are generated following T cell receptor (TCR) stimulation and bind to different domains in the RasGRP and SOS RasGEFs to facilitate the activation of the membrane-anchored Ras GTPases. In this review we highlight how different lipid-based elements are generated by various enzymes downstream of the TCR and other receptors and how these dynamic and interrelated lipid products may fine-tune Ras activation by RasGEFs in developing T cells.
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Affiliation(s)
- Jesse E Jun
- Department of Anatomy, University of California San Francisco , San Francisco, CA , USA
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42
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Philipsen L, Engels T, Schilling K, Gurbiel S, Fischer KD, Tedford K, Schraven B, Gunzer M, Reichardt P. Multimolecular analysis of stable immunological synapses reveals sustained recruitment and sequential assembly of signaling clusters. Mol Cell Proteomics 2013; 12:2551-67. [PMID: 23754785 DOI: 10.1074/mcp.m112.025205] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The formation of the immunological synapse between T cells and antigen-presenting cells (APC) begins within minutes of contact and can take hours for full T-cell activation. Although early phases of the synapse have been extensively studied for a select number of proteins, later phases have not yet been examined in detail. We studied the signaling network in stable synapses by measuring the simultaneous localization of 25 signaling and structural molecules over 2 h at the level of individual synapses using multi-epitope ligand cartography (MELC). Signaling proteins including phospho(p)ZAP70, pSLP76, pCD3ζ, and pLAT, along with proteins that influence synapse structure such as F-actin, tubulin, CD45, and ICAM-1, were localized in images of synapses and revealed the multidimensional construction of a mature synapse. The construction of the stable synapse included intense early TCR signaling, a phase of recruitment of structural proteins, and a sustained increase in signaling molecules and colocalization of TCR and pLAT signaling clusters in the center of the synapse. Consolidation of TCR and associated proteins resulted in formation of a small number of discrete synaptic microclusters. Development of synapses and cSMAC composition was greatly affected by the absence of Vav1, with an associated loss in PLCγ1 recruitment, pSLP76, and increased CXCR4. Together, these data demonstrate the use of multi-epitope ligand cartography to quantitatively analyze synapse formation and reveal successive recruitment of structural and signaling proteins and sustained phosphorylation at the mature synapse.
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Affiliation(s)
- Lars Philipsen
- Otto von Guericke University, Institute of Molecular and Clinical Immunology, Leipziger Str. 44, 39120 Magdeburg, Germany
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43
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The membrane adaptor LAT is proteolytically cleaved following Fas engagement in a tyrosine phosphorylation-dependent fashion. Biochem J 2013; 450:511-21. [PMID: 23240581 DOI: 10.1042/bj20121135] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Engagement of the TCR (T-cell receptor) induces tyrosine phosphorylation of the LAT (linker for the activation of T-cells) adaptor, and thereby it recruits several cytosolic mediators for downstream signalling pathways. The Fas protein is essential for T-lymphocyte apoptosis, and following Fas engagement, many proteins are proteolytically cleaved, including several molecules that are important for the transduction of TCR intracellular signals. In the present study, we demonstrate that the adaptor LAT is also subject to a proteolytic cleavage in mature T-lymphocytes and thymocytes in response to Fas engagement, and also on TCR stimulation, and we identify three aspartic acid residues at which LAT is cleaved. Interestingly, these aspartic acid residues are located in proximity to several functionally important tyrosine residues of LAT, raising the possibility that their phosphorylation could modulate LAT cleavage. Consistent with that hypothesis, we show that induction of phosphorylation by pervanadate or H2O2 in Jurkat cells and thymocytes inhibits Fas-mediated cleavage of LAT. Moreover, we show that LAT proteolysis is also enhanced during anergy induction of primary human T-cells, suggesting that LAT cleavage may act as a regulator of TCR-mediated activation of T-cells and not only as a transducer of cell death promoting stimuli.
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44
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Xie JJ, Liang JQ, Diao LH, Altman A, Li Y. TNFR-associated factor 6 regulates TCR signaling via interaction with and modification of LAT adapter. THE JOURNAL OF IMMUNOLOGY 2013; 190:4027-36. [PMID: 23514740 DOI: 10.4049/jimmunol.1202742] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
TNFR-associated factor (TRAF)6 is an essential ubiquitin E3 ligase in immune responses, but its function in adaptive immunity is not well understood. In this study, we show that TRAF6 is recruited to the peripheral ring of the T cell immunological synapse in Jurkat T cells or human primary CD4(+) T cells conjugated with staphylococcal enterotoxin E-pulsed B cells. This recruitment depends on TRAF6 interacting with linker for activation of T cells (LAT) via its TRAF domain. Although LAT was indispensable for TCR/CD28-induced TRAF6 ubiquitination and its ligase activity, RNA interference-induced TRAF6 knockdown in T cells decreased TCR/CD28-induced LAT ubiquitination, tyrosine phosphorylation, and association with tyrosine kinase ZAP70. Overexpression of TRAF6 or its catalytically inactive form C70A promoted and decreased, respectively, LAT tyrosine phosphorylation upon stimulation. Moreover, LAT was ubiquitinated at Lys(88) by TRAF6 via K63-linked chain. In addition, TRAF6 was required for and synergized with LAT to promote the TCR/CD28-induced activation of NFAT. These results reveal a novel function and mechanism of TRAF6 action in the TCR-LAT signaling pathway distinct from its role in TCR-induced NF-κB activation, indicating that LAT also plays an adapter role in TCR/CD28-induced activation of TRAF6.
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Affiliation(s)
- Ji-Ji Xie
- State Key Laboratory of Biocontrol, Key Laboratory of Gene Engineering of Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
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45
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Bartelt RR, Houtman JCD. The adaptor protein LAT serves as an integration node for signaling pathways that drive T cell activation. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2012; 5:101-10. [PMID: 23150273 DOI: 10.1002/wsbm.1194] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
T cells are essential for the adaptive immune response to pathogens. However, dysfunctional T cell activity has been implicated in numerous diseases, including the failure of organ transplants, allergic reactions, asthma, autoimmune disorders, and coronary artery disease. T cell responses to pathogens require the induction of the primary activating receptor, the T cell receptor (TCR), along with other costimulatory and adhesion receptors. Signal transduction pathways activated downstream of these receptors drive T cell responses required for the immune response and disease progression. A key question in our understanding of the mechanism of T cell activation is how signaling pathways emanating from multiple receptors integrate together to alter T cell effector functions. One integration node for intracellular signaling is the membrane-associated adaptor protein linker for the activation of T cells or LAT. Upon stimulation of the TCR and other receptors, LAT is phosphorylated at several tyrosines residues on its cytoplasmic tail. This leads to the binding of SH2 domain-containing proteins and their associated molecules and the formation of large multiprotein complexes. These dynamic and highly regulated signaling complexes facilitate the production of second messengers, activate downstream pathways, induce actin cytoskeleton polymerization, and stimulate the activity of multiple transcription factors. Thus, signaling pathways from several receptors feed into LAT, which then integrates this information and selectively induces pathways critical for T cell activation and the adaptive immune response.
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46
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Fuller DM, Zhu M, Ou-Yang CW, Sullivan SA, Zhang W. A tale of two TRAPs: LAT and LAB in the regulation of lymphocyte development, activation, and autoimmunity. Immunol Res 2011; 49:97-108. [PMID: 21136199 DOI: 10.1007/s12026-010-8197-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Transmembrane adaptor proteins (TRAPs) link antigen receptor engagement to downstream cellular processes. Although these proteins typically lack intrinsic enzymatic activity, they are phosphorylated on multiple tyrosine residues following lymphocyte activation, allowing them to function as scaffolds for the assembly of multi-molecular signaling complexes. Among the many TRAPs that have been discovered in recent years, the LAT (linker for activation of T cells) family of adaptor proteins plays an important role in the positive and negative regulation of lymphocyte maturation, activation, and differentiation. Of the two members in this family, LAT is an indispensable component controlling T cell and mast cell activation and function; LAB (linker for activation of B cells), also called NTAL, is necessary to fine-tune lymphocyte activation and may be a key regulator of innate immune responses. Here, we review recent advances on the function of LAT and LAB in the regulation of development and activation of immune cells.
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Affiliation(s)
- Deirdre M Fuller
- Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
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47
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Kremer KN, Clift IC, Miamen AG, Bamidele AO, Qian NX, Humphreys TD, Hedin KE. Stromal cell-derived factor-1 signaling via the CXCR4-TCR heterodimer requires phospholipase C-β3 and phospholipase C-γ1 for distinct cellular responses. THE JOURNAL OF IMMUNOLOGY 2011; 187:1440-7. [PMID: 21705626 DOI: 10.4049/jimmunol.1100820] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The CXCR4 chemokine receptor is a G protein-coupled receptor that signals in T lymphocytes by forming a heterodimer with the TCR. CXCR4 and TCR functions are consequently highly cross regulated, affecting T cell immune activation, cytokine secretion, and T cell migration. The CXCR4-TCR heterodimer stimulates T cell migration and activation of the ERK MAPK and downstream AP-1-dependent cytokine transcription in response to stromal cell-derived factor-1 (SDF-1), the sole chemokine ligand of CXCR4. These responses require Gi-type G proteins as well as TCR ITAM domains and the ZAP70 tyrosine kinase, thus indicating that the CXCR4-TCR heterodimer signals to integrate G protein-coupled receptor-associated and TCR-associated signaling molecules in response to SDF-1. Yet, the phospholipase C (PLC) isozymes responsible for coupling the CXCR4-TCR heterodimer to distinct downstream cellular responses are incompletely characterized. In this study, we demonstrate that PLC activity is required for SDF-1 to induce ERK activation, migration, and CXCR4 endocytosis in human T cells. SDF-1 signaling via the CXCR4-TCR heterodimer uses PLC-β3 to activate the Ras-ERK pathway and increase intracellular calcium ion concentrations, whereas PLC-γ1 is dispensable for these outcomes. In contrast, PLC-γ1, but not PLC-β3, is required for SDF-1-mediated migration via a mechanism independent of LAT. These results increase understanding of the signaling mechanisms employed by the CXCR4-TCR heterodimer, characterize new roles for PLC-β3 and PLC-γ1 in T cells, and suggest that multiple PLCs may also be activated downstream of other chemokine receptors to distinctly regulate migration versus other signaling functions.
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Affiliation(s)
- Kimberly N Kremer
- Department of Immunology, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN 55905, USA
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48
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Abstract
The spatial and temporal organization of molecules within a cell is critical for coordinating the many distinct activities carried out by the cell. In an increasing number of biological signaling processes, scaffold proteins have been found to play a central role in physically assembling the relevant molecular components. Although most scaffolds use a simple tethering mechanism to increase the efficiency of interaction between individual partner molecules, these proteins can also exert complex allosteric control over their partners and are themselves the target of regulation. Scaffold proteins offer a simple, flexible strategy for regulating selectivity in pathways, shaping output behaviors, and achieving new responses from preexisting signaling components. As a result, scaffold proteins have been exploited by evolution, pathogens, and cellular engineers to reshape cellular behavior.
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Affiliation(s)
- Matthew C Good
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA
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49
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Itk: the rheostat of the T cell response. JOURNAL OF SIGNAL TRANSDUCTION 2011; 2011:297868. [PMID: 21747996 PMCID: PMC3116522 DOI: 10.1155/2011/297868] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 01/19/2011] [Indexed: 12/28/2022]
Abstract
The nonreceptor tyrosine kinase Itk plays a key role in TCR-initiated signaling that directly and significantly affects the regulation of PLCγ1 and the consequent mobilization of Ca2+. Itk also participates in the regulation of cytoskeletal reorganization as well as cellular adhesion, which is necessary for a productive T cell response. The functional cellular outcome of these molecular regulations by Itk renders it an important mediator of T cell development and differentiation. This paper encompasses the structure of Itk, the signaling parameters leading to Itk activation, and Itk effects on molecular pathways resulting in functional cellular outcomes. The incorporation of these factors persuades one to believe that Itk serves as a modulator, or rheostat, critically fine-tuning the T cell response.
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50
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Sylvain NR, Nguyen K, Bunnell SC. Vav1-mediated scaffolding interactions stabilize SLP-76 microclusters and contribute to antigen-dependent T cell responses. Sci Signal 2011; 4:ra14. [PMID: 21386095 DOI: 10.1126/scisignal.2001178] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The guanine nucleotide exchange factor (GEF) Vav1 synergizes with the adaptor protein SLP-76 (Src homology 2 domain--containing leukocyte phosphoprotein of 76 kD) to support T cell development and activation. In response to ligation of the T cell receptor (TCR), SLP-76 is assembled into microclusters that provide an essential platform for the signaling events that drive T cell activation. We found that Vav1 selectively entered SLP-76 microclusters, rather than TCR microclusters, influencing their stability and function. The carboxyl terminus of Vav1, which consists of Src homology domains, was both necessary and sufficient for the entry of Vav1 into SLP-76 microclusters; however, this fragment of Vav1 was insufficient to stabilize the microclusters, and it potently suppressed T cell activation. This indicated that the amino terminus of Vav1, which has the GEF domain, also contributed to the integrity of SLP-76 microclusters and thereby to T cell activation. These microcluster-stabilizing functions were independent of the GEF activity in the amino terminus of Vav1 and were unaffected if the GEF function of Vav1 was either inactivated or constitutively activated by mutation. In contrast, Vav1 deletion mutants lacking either the calponin homology domain or the catalytic core of the GEF exhibited mild scaffolding defects, but they differentially affected TCR-dependent calcium ion (Ca²+) responses. We conclude that multiple GEF-independent scaffolding functions distributed throughout the amino terminus of Vav1 contribute to the activation of T cells by acting synergistically to increase the stability and function of SLP-76 microclusters.
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Affiliation(s)
- Nicholas R Sylvain
- Program in Immunology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111, USA
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