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Abstract
T cell activation is initiated by the recognition of specific antigenic peptides and subsequently accomplished by complex signaling cascades. These aspects have been extensively studied for decades as pivotal factors in the establishment of adaptive immunity. However, how receptors or signaling molecules are organized in the resting state prior to encountering antigens has received less attention. Recent advancements in super-resolution microscopy techniques have revealed topographically controlled pre-formed organization of key molecules involved in antigen recognition and signal transduction on microvillar projections of T cells before activation and substantial effort has been dedicated to characterizing the topological structure of resting T cells over the past decade. This review will summarize our current understanding of how key surface receptors are pre-organized on the T-cell plasma membrane and discuss the potential role of these receptors, which are preassembled prior to ligand binding in the early activation events of T cells.
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Affiliation(s)
- Yunmin Jung
- Department of Nano-Biomedical Engineering, Advanced Science Institute, Yonsei University, Seoul, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science, Seoul, Republic of Korea
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2
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Isser A, Livingston NK, Schneck JP. Biomaterials to enhance antigen-specific T cell expansion for cancer immunotherapy. Biomaterials 2021; 268:120584. [PMID: 33338931 PMCID: PMC7856270 DOI: 10.1016/j.biomaterials.2020.120584] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 11/22/2020] [Accepted: 11/26/2020] [Indexed: 02/07/2023]
Abstract
T cells are often referred to as the 'guided missiles' of our immune system because of their capacity to traffic to and accumulate at sites of infection or disease, destroy infected or mutated cells with high specificity and sensitivity, initiate systemic immune responses, sterilize infections, and produce long-lasting memory. As a result, they are a common target for a range of cancer immunotherapies. However, the myriad of challenges of expanding large numbers of T cells specific to each patient's unique tumor antigens has led researchers to develop alternative, more scalable approaches. Biomaterial platforms for expansion of antigen-specific T cells offer a path forward towards broadscale translation of personalized immunotherapies by providing "off-the-shelf", yet modular approaches to customize the phenotype, function, and specificity of T cell responses. In this review, we discuss design considerations and progress made in the development of ex vivo and in vivo technologies for activating antigen-specific T cells, including artificial antigen presenting cells, T cell stimulating scaffolds, biomaterials-based vaccines, and artificial lymphoid organs. Ultimate translation of these platforms as a part of cancer immunotherapy regimens hinges on an in-depth understanding of T cell biology and cell-material interactions.
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Affiliation(s)
- Ariel Isser
- Department of Biomedical Engineering, School of Medicine, USA; Institute for Cell Engineering, School of Medicine, USA
| | - Natalie K Livingston
- Department of Biomedical Engineering, School of Medicine, USA; Institute for Cell Engineering, School of Medicine, USA; Translational Tissue Engineering Center, USA; Institute for Nanobiotechnology, USA
| | - Jonathan P Schneck
- Institute for Cell Engineering, School of Medicine, USA; Department of Pathology, School of Medicine, USA; Institute for Nanobiotechnology, USA; Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
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3
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Schamel WW, Alarcon B, Minguet S. The TCR is an allosterically regulated macromolecular machinery changing its conformation while working. Immunol Rev 2020; 291:8-25. [PMID: 31402501 DOI: 10.1111/imr.12788] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 05/30/2019] [Indexed: 12/13/2022]
Abstract
The αβ T-cell receptor (TCR) is a multiprotein complex controlling the activation of T cells. Although the structure of the complete TCR is not known, cumulative evidence supports that the TCR cycles between different conformational states that are promoted either by thermal motion or by force. These structural transitions determine whether the TCR engages intracellular effectors or not, regulating TCR phosphorylation and signaling. As for other membrane receptors, ligand binding selects and stabilizes the TCR in active conformations, and/or switches the TCR to activating states that were not visited before ligand engagement. Here we review the main models of TCR allostery, that is, ligand binding at TCRαβ changes the structure at CD3 and ζ. (a) The ITAM and proline-rich sequence exposure model, in which the TCR's cytoplasmic tails shield each other and ligand binding exposes them for phosphorylation. (b) The membrane-ITAM model, in which the CD3ε and ζ tails are sequestered inside the membrane and again ligand binding exposes them. (c) The mechanosensor model in which ligand binding exerts force on the TCR, inducing structural changes that allow signaling. Since these models are complementary rather than competing, we propose a unified model that aims to incorporate all existing data.
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Affiliation(s)
- Wolfgang W Schamel
- Department of Immunology, Faculty of Biology, Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Center of Chronic Immunodeficiency CCI, University Clinics and Medical Faculty, Freiburg, Germany
| | - Balbino Alarcon
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | - Susana Minguet
- Department of Immunology, Faculty of Biology, Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Center of Chronic Immunodeficiency CCI, University Clinics and Medical Faculty, Freiburg, Germany
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4
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Abstract
T cell receptors (TCRs) are protein complexes formed by six different polypeptides. In most T cells, TCRs are composed of αβ subunits displaying immunoglobulin-like variable domains that recognize peptide antigens associated with major histocompatibility complex molecules expressed on the surface of antigen-presenting cells. TCRαβ subunits are associated with the CD3 complex formed by the γ, δ, ε, and ζ subunits, which are invariable and ensure signal transduction. Here, we review how the expression and function of TCR complexes are orchestrated by several fine-tuned cellular processes that encompass (a) synthesis of the subunits and their correct assembly and expression at the plasma membrane as a single functional complex, (b) TCR membrane localization and dynamics at the plasma membrane and in endosomal compartments, (c) TCR signal transduction leading to T cell activation, and (d) TCR degradation. These processes balance each other to ensure efficient T cell responses to a variety of antigenic stimuli while preventing autoimmunity.
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Affiliation(s)
- Andrés Alcover
- Lymphocyte Cell Biology Unit, INSERM U1221, Department of Immunology, Institut Pasteur, Paris 75015, France; ,
| | - Balbino Alarcón
- Severo Ochoa Center for Molecular Biology, CSIC-UAM, Madrid 28049, Spain;
| | - Vincenzo Di Bartolo
- Lymphocyte Cell Biology Unit, INSERM U1221, Department of Immunology, Institut Pasteur, Paris 75015, France; ,
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5
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Schamel WWA, Alarcon B, Höfer T, Minguet S. The Allostery Model of TCR Regulation. THE JOURNAL OF IMMUNOLOGY 2017; 198:47-52. [PMID: 27994168 DOI: 10.4049/jimmunol.1601661] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 11/01/2016] [Indexed: 12/20/2022]
Abstract
The activity of the αβ TCR is controlled by conformational switches. In the resting conformation, the TCR is not phosphorylated and is inactive. Binding of multivalent peptide-MHC to the TCR stabilizes the active conformation, leading to TCR signaling. These two conformations allow the TCRs to be allosterically regulated. We review recent data on heterotropic allostery where peptide-MHC and membrane cholesterol serve opposing functions as positive and negative allosteric regulators, respectively. In resting T cells cholesterol keeps TCRs in the resting conformation that otherwise would become spontaneously active. This regulation is well described by the classical Monod-Wyman-Changeux model of allostery. Moreover, the observation that TCRs assemble into nanoclusters might allow for homotropic allostery, in which individual TCRs could positively cooperate and thus enhance the sensitivity of T cell activation. This new view of TCR regulation will contribute to a better understanding of TCR functioning.
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Affiliation(s)
- Wolfgang W A Schamel
- Department of Immunology, Institute for Biology III, Faculty of Biology, University of Freiburg, 79108 Freiburg, Germany; .,BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany.,Center for Chronic Immunodeficiency, Medical Center, University of Freiburg, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
| | - Balbino Alarcon
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Thomas Höfer
- Division of Theoretical Systems Biology, German Cancer Research Center, 69120 Heidelberg, Germany; and.,BioQuant Center, University of Heidelberg, 69120 Heidelberg, Germany
| | - Susana Minguet
- Department of Immunology, Institute for Biology III, Faculty of Biology, University of Freiburg, 79108 Freiburg, Germany.,BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany
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6
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Singha S, Shao K, Yang Y, Clemente-Casares X, Solé P, Clemente A, Blanco J, Dai Q, Song F, Liu SW, Yamanouchi J, Umeshappa CS, Nanjundappa RH, Detampel P, Amrein M, Fandos C, Tanguay R, Newbigging S, Serra P, Khadra A, Chan WCW, Santamaria P. Peptide-MHC-based nanomedicines for autoimmunity function as T-cell receptor microclustering devices. NATURE NANOTECHNOLOGY 2017; 12:701-710. [PMID: 28436959 DOI: 10.1038/nnano.2017.56] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 03/06/2017] [Indexed: 05/23/2023]
Abstract
We have shown that nanoparticles (NPs) can be used as ligand-multimerization platforms to activate specific cellular receptors in vivo. Nanoparticles coated with autoimmune disease-relevant peptide-major histocompatibility complexes (pMHC) blunted autoimmune responses by triggering the differentiation and expansion of antigen-specific regulatory T cells in vivo. Here, we define the engineering principles impacting biological activity, detail a synthesis process yielding safe and stable compounds, and visualize how these nanomedicines interact with cognate T cells. We find that the triggering properties of pMHC-NPs are a function of pMHC intermolecular distance and involve the sustained assembly of large antigen receptor microclusters on murine and human cognate T cells. These compounds show no off-target toxicity in zebrafish embryos, do not cause haematological, biochemical or histological abnormalities, and are rapidly captured by phagocytes or processed by the hepatobiliary system. This work lays the groundwork for the design of ligand-based NP formulations to re-program in vivo cellular responses using nanotechnology.
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Affiliation(s)
- Santiswarup Singha
- Julia McFarlane Diabetes Research Centre (JMDRC) and Department of Microbiology, Immunology and Infectious Diseases, Snyder Institute for Chronic Diseases and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Kun Shao
- Julia McFarlane Diabetes Research Centre (JMDRC) and Department of Microbiology, Immunology and Infectious Diseases, Snyder Institute for Chronic Diseases and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Yang Yang
- Julia McFarlane Diabetes Research Centre (JMDRC) and Department of Microbiology, Immunology and Infectious Diseases, Snyder Institute for Chronic Diseases and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Xavier Clemente-Casares
- Julia McFarlane Diabetes Research Centre (JMDRC) and Department of Microbiology, Immunology and Infectious Diseases, Snyder Institute for Chronic Diseases and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Patricia Solé
- Institut D'Investigacions Biomèdiques August Pi i Sunyer, Barcelona 08036, Spain
| | - Antonio Clemente
- Institut D'Investigacions Biomèdiques August Pi i Sunyer, Barcelona 08036, Spain
| | - Jesús Blanco
- Institut D'Investigacions Biomèdiques August Pi i Sunyer, Barcelona 08036, Spain
| | - Qin Dai
- Institute of Biomaterials and Biomedical Engineering, Departments of Chemistry, Chemical Engineering, and Materials Sciences and Engineering, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada
| | - Fayi Song
- Institute of Biomaterials and Biomedical Engineering, Departments of Chemistry, Chemical Engineering, and Materials Sciences and Engineering, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada
| | - Shang Wan Liu
- Department of Physiology, McGill University, McIntyre Medical Building, Montreal, Quebec H3G 1Y6, Canada
| | - Jun Yamanouchi
- Julia McFarlane Diabetes Research Centre (JMDRC) and Department of Microbiology, Immunology and Infectious Diseases, Snyder Institute for Chronic Diseases and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Channakeshava Sokke Umeshappa
- Julia McFarlane Diabetes Research Centre (JMDRC) and Department of Microbiology, Immunology and Infectious Diseases, Snyder Institute for Chronic Diseases and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Roopa Hebbandi Nanjundappa
- Julia McFarlane Diabetes Research Centre (JMDRC) and Department of Microbiology, Immunology and Infectious Diseases, Snyder Institute for Chronic Diseases and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Pascal Detampel
- Departments of Cell Biology and Anatomy, and Pathology &Laboratory Medicine, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Matthias Amrein
- Departments of Cell Biology and Anatomy, and Pathology &Laboratory Medicine, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - César Fandos
- Institut D'Investigacions Biomèdiques August Pi i Sunyer, Barcelona 08036, Spain
| | - Robert Tanguay
- Environmental &Molecular Toxicology Sinnhuber Aquatic Research Laboratory, Oregon State University, Corvalis, Oregon 97333, USA
| | - Susan Newbigging
- Center for Modeling Human Disease, Toronto Centre for Phenogenomics, Lunenfeld Research Institute, 25 Orde Street, Toronto, Ontario M5T 3H7, Canada
| | - Pau Serra
- Institut D'Investigacions Biomèdiques August Pi i Sunyer, Barcelona 08036, Spain
| | - Anmar Khadra
- Department of Physiology, McGill University, McIntyre Medical Building, Montreal, Quebec H3G 1Y6, Canada
| | - Warren C W Chan
- Institute of Biomaterials and Biomedical Engineering, Departments of Chemistry, Chemical Engineering, and Materials Sciences and Engineering, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada
| | - Pere Santamaria
- Julia McFarlane Diabetes Research Centre (JMDRC) and Department of Microbiology, Immunology and Infectious Diseases, Snyder Institute for Chronic Diseases and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Institut D'Investigacions Biomèdiques August Pi i Sunyer, Barcelona 08036, Spain
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7
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Jung Y, Riven I, Feigelson SW, Kartvelishvily E, Tohya K, Miyasaka M, Alon R, Haran G. Three-dimensional localization of T-cell receptors in relation to microvilli using a combination of superresolution microscopies. Proc Natl Acad Sci U S A 2016; 113:E5916-E5924. [PMID: 27647916 PMCID: PMC5056101 DOI: 10.1073/pnas.1605399113] [Citation(s) in RCA: 126] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Leukocyte microvilli are flexible projections enriched with adhesion molecules. The role of these cellular projections in the ability of T cells to probe antigen-presenting cells has been elusive. In this study, we probe the spatial relation of microvilli and T-cell receptors (TCRs), the major molecules responsible for antigen recognition on the T-cell membrane. To this end, an effective and robust methodology for mapping membrane protein distribution in relation to the 3D surface structure of cells is introduced, based on two complementary superresolution microscopies. Strikingly, TCRs are found to be highly localized on microvilli, in both peripheral blood human T cells and differentiated effector T cells, and are barely found on the cell body. This is a decisive demonstration that different types of T cells universally localize their TCRs to microvilli, immediately pointing to these surface projections as effective sensors for antigenic moieties. This finding also suggests how previously reported membrane clusters might form, with microvilli serving as anchors for specific T-cell surface molecules.
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Affiliation(s)
- Yunmin Jung
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Inbal Riven
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sara W Feigelson
- Department of Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
| | | | - Kazuo Tohya
- Department of Anatomy, Kansai University of Health Sciences, Kumatori, Osaka 590-0482, Japan
| | - Masayuki Miyasaka
- Institute for Academic Initiatives, Osaka University, Suita, Osaka 565-0871, Japan; MediCity Research Laboratory, University of Turku, FI-20521, Turku, Finland
| | - Ronen Alon
- Department of Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Gilad Haran
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel;
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8
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Beck-García K, Beck-García E, Bohler S, Zorzin C, Sezgin E, Levental I, Alarcón B, Schamel WW. Nanoclusters of the resting T cell antigen receptor (TCR) localize to non-raft domains. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:802-9. [DOI: 10.1016/j.bbamcr.2014.12.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 12/04/2014] [Accepted: 12/15/2014] [Indexed: 10/24/2022]
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9
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Abstract
αβ T-cell receptor (TCR) activation plays a crucial role for T-cell function. However, the TCR itself does not possess signaling domains. Instead, the TCR is noncovalently coupled to a conserved multisubunit signaling apparatus, the CD3 complex, that comprises the CD3εγ, CD3εδ, and CD3ζζ dimers. How antigen ligation by the TCR triggers CD3 activation and what structural role the CD3 extracellular domains (ECDs) play in the assembled TCR-CD3 complex remain unclear. Here, we use two complementary structural approaches to gain insight into the overall organization of the TCR-CD3 complex. Small-angle X-ray scattering of the soluble TCR-CD3εδ complex reveals the CD3εδ ECDs to sit underneath the TCR α-chain. The observed arrangement is consistent with EM images of the entire TCR-CD3 integral membrane complex, in which the CD3εδ and CD3εγ subunits were situated underneath the TCR α-chain and TCR β-chain, respectively. Interestingly, the TCR-CD3 transmembrane complex bound to peptide-MHC is a dimer in which two TCRs project outward from a central core composed of the CD3 ECDs and the TCR and CD3 transmembrane domains. This arrangement suggests a potential ligand-dependent dimerization mechanism for TCR signaling. Collectively, our data advance our understanding of the molecular organization of the TCR-CD3 complex, and provides a conceptual framework for the TCR activation mechanism.
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10
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Sulfamethoxazole induces a switch mechanism in T cell receptors containing TCRVβ20-1, altering pHLA recognition. PLoS One 2013; 8:e76211. [PMID: 24116097 PMCID: PMC3792127 DOI: 10.1371/journal.pone.0076211] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 08/21/2013] [Indexed: 11/19/2022] Open
Abstract
T cell receptors (TCR) containing Vβ20-1 have been implicated in a wide range of T cell mediated disease and allergic reactions, making it a target for understanding these. Mechanics of T cell receptors are largely unexplained by static structures available from x-ray crystallographic studies. A small number of molecular dynamic simulations have been conducted on TCR, however are currently lacking either portions of the receptor or explanations for differences between binding and non-binding TCR recognition of respective peptide-HLA. We performed molecular dynamic simulations of a TCR containing variable domain Vβ20-1, sequenced from drug responsive T cells. These were initially from a patient showing maculopapular eruptions in response to the sulfanilamide-antibiotic sulfamethoxazole (SMX). The CDR2β domain of this TCR was found to dock SMX with high affinity. Using this compound as a perturbation, overall mechanisms involved in responses mediated by this receptor were explored, showing a chemical action on the TCR free from HLA or peptide interaction. Our simulations show two completely separate modes of binding cognate peptide-HLA complexes, with an increased affinity induced by SMX bound to the Vβ20-1. Overall binding of the TCR is mediated through a primary recognition by either the variable β or α domain, and a switch in recognition within these across TCR loops contacting the peptide and HLA occurs when SMX is present in the CDR2β loop. Large binding affinity differences are induced by summed small amino acid changes primarily by SMX modifying only three critical CDR2β loop amino acid positions. These residues, TYRβ57, ASPβ64, and LYSβ65 initially hold hydrogen bonds from the CDR2β to adjacent CDR loops. Effects from SMX binding are amplified and traverse longer distances through internal TCR hydrogen bonding networks, controlling the overall TCR conformation. Thus, the CDR2β of Vβ20-1 acts as a ligand controlled switch affecting overall TCR binding affinity.
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11
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Abstract
Nanotechnology uses the unique properties of objects that function as a unit within the overall size range of 1-1,000 nanometres. The engineering of nanostructure materials, including nanoparticles, nanoemulsions or nanotubules, holds great promise for the development of new immunomodulatory agents, as such nanostructures can be used to more effectively manipulate or deliver immunologically active components to target sites. Successful applications of nanotechnology in the field of immunology will enable new generations of vaccines, adjuvants and immunomodulatory drugs that aim to improve clinical outcomes in response to a range of infectious and non-infectious diseases.
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12
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Abstract
Despite the low affinity of the T-cell antigen receptor (TCR) for its peptide/major histocompatibility complex (pMHC) ligand, T cells are very sensitive to their antigens. This paradox can be resolved if we consider that the TCR may be organized into pre-existing oligomers or nanoclusters. Such structures could improve antigen recognition by increasing the functional affinity (avidity) of the TCR-pMHC interaction and by allowing cooperativity between individual TCRs. Up to approximately 20 TCRs become tightly apposed in these nanoclusters, often in a linear manner, and such structures could reflect a relatively generalized phenomenon: the non-random concentration of membrane receptors in specific areas of the plasma membrane known as protein islands. The association of TCRs into nanoclusters can explain the enhanced kinetics of the pMHC-TCR interaction in two dimensional versus three dimensional systems, but also their existence calls for a revision of the TCR triggering models based on pMHC-induced TCR clustering. Interestingly, the B-cell receptor and the FcεRI have also been shown to form nanoclusters, suggesting that the formation of pre-existing receptor oligomers could be widely used in the immune system.
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Affiliation(s)
- Wolfgang W A Schamel
- Department of Molecular Immunology, Institute of Biology III, Faculty of Biology, BIOSS Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany
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13
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Abstract
Activation and expansion of drug reactive T cells are key features in drug hypersensitivity reactions. Drugs may interact directly with immune receptors such as the human leukocyte antigens (HLA) or the T-cell receptors (TCR) itself, the pharmacological interaction [p-i] concept. To analyze whether the drug sulfamethoxazole (SMX) interacts directly with the TCR and thereby contributing to signaling and T cell activation, we analyze two SMX specific T cell clones (TCC “1.3” and “H13”). Proliferation to SMX and 11 related sulfanilamides, Ca++ influx in drug stimulated T-cells and the inhibitory effect of non-reactive sulfanilamides on SMX stimulation were analyzed. In silico docking of SMX and related sulfanilamide to the TCR were used to identify possible drug binding sites, and correlated to in vitro data to find the correct docking. In Ca++ influx assays, reactions occurred as early as 14 sec after adding SMX to TCC and APC. The broadly reactive clone (“H13”) was stimulated by 5 additional sulfanilamide, while one TCC (“1.3”) was reactive exclusively with SMX but not other sulfanilamides. Competition experiments with sulfanilamide inhibited SMX induced Ca++ influx and proliferation of the TCC 1.3 in a dose dependent way. Docking experiments with SMX and related sulfanilamides confirmed and explained the in vitro data as docking localized binding sites for SMX and the 5 stimulating sulfanilamides on the CDR2ß domain of the clone H13, while the 6 non-stimulatory SA failed to bind. In TCC 1.3, SMX could be docked on the CDR3α of the TCR. The other, non-stimulatory but inhibitory SA could also be docked to the same site. The combined analysis of in vitro and in silico data show that sulfanilamide can bind directly to TCRs. It shows that TCR, like other receptors, appear to be reamenable to manipulations by small molecules.
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Affiliation(s)
- Stephan Watkins
- Department of Rheumatology, Clinical Immunology and Allergology, Inselspital/University Hospital of Bern, Bern, Switzerland
- Department of Graduate Cell Biology and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Werner J. Pichler
- Department of Rheumatology, Clinical Immunology and Allergology, Inselspital/University Hospital of Bern, Bern, Switzerland
- Corresponding Author:
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14
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Fiala GJ, Rejas MT, Schamel WW, van Santen HM. Visualization of TCR Nanoclusters via Immunogold Labeling, Freeze-Etching, and Surface Replication. Methods Cell Biol 2013; 117:391-410. [DOI: 10.1016/b978-0-12-408143-7.00021-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
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15
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Blanco R, Alarcón B. TCR Nanoclusters as the Framework for Transmission of Conformational Changes and Cooperativity. Front Immunol 2012; 3:115. [PMID: 22582078 PMCID: PMC3348506 DOI: 10.3389/fimmu.2012.00115] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 04/22/2012] [Indexed: 12/30/2022] Open
Abstract
Increasing evidence favors the notion that, before triggering, the T cell antigen receptor (TCR) forms nanometer-scale oligomers that are called nanoclusters. The organization of the TCR in pre-existing oligomers cannot be ignored when analyzing the properties of ligand (pMHC) recognition and signal transduction. As with other membrane receptors, the existence of TCR oligomers points out to cooperativity phenomena. We review the data in support of conformational changes in the TCR as the basic principle to transduce the activation signal to the cytoplasm and the incipient data suggesting cooperativity within nanoclusters.
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Affiliation(s)
- Raquel Blanco
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid Madrid, Spain
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16
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Louis-Dit-Sully C, Kubatzky KF, Lindquist JA, Blattner C, Janssen O, Schamel WWA. Meeting report: Signal transduction meets systems biology. Cell Commun Signal 2012; 10:11. [PMID: 22546078 PMCID: PMC3499392 DOI: 10.1186/1478-811x-10-11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 04/07/2012] [Indexed: 11/18/2022] Open
Abstract
In the 21st century, systems-wide analyses of biological processes are getting more and more realistic. Especially for the in depth analysis of signal transduction pathways and networks, various approaches of systems biology are now successfully used. The EU FP7 large integrated project SYBILLA (Systems Biology of T-cell Activation in Health and Disease) coordinates such an endeavor. By using a combination of experimental data sets and computational modelling, the consortium strives for gaining a detailed and mechanistic understanding of signal transduction processes that govern T-cell activation. In order to foster the interaction between systems biologists and experimentally working groups, SYBILLA co-organized the 15th meeting “Signal Transduction: Receptors, Mediators and Genes” together with the Signal Transduction Society (STS). Thus, the annual STS conference, held from November 7 to 9, 2011 in Weimar, Germany, provided an interdisciplinary forum for research on signal transduction with a major focus on systems biology addressing signalling events in T-cells. Here we report on a selection of ongoing projects of SYBILLA and how they were discussed at this interdisciplinary conference.
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Affiliation(s)
- Christine Louis-Dit-Sully
- Max Planck Institute of Immunobiology and Epigenetics and Biology III, Faculty of Biology, University of Freiburg, 79108, Freiburg, Germany.
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Kumar R, Ferez M, Swamy M, Arechaga I, Rejas MT, Valpuesta JM, Schamel WWA, Alarcon B, van Santen HM. Increased sensitivity of antigen-experienced T cells through the enrichment of oligomeric T cell receptor complexes. Immunity 2011; 35:375-87. [PMID: 21903423 DOI: 10.1016/j.immuni.2011.08.010] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 05/11/2011] [Accepted: 08/23/2011] [Indexed: 12/25/2022]
Abstract
Although memory T cells respond more vigorously to stimulation and they are more sensitive to low doses of antigen than naive T cells, the molecular basis of this increased sensitivity remains unclear. We have previously shown that the T cell receptor (TCR) exists as different-sized oligomers on the surface of resting T cells and that large oligomers are preferentially activated in response to low antigen doses. Through biochemistry and electron microscopy, we now showed that previously stimulated and memory T cells have more and larger TCR oligomers at the cell surface than their naive counterparts. Reconstitution of cells and mice with a point mutant of the CD3ζ subunit, which impairs TCR oligomer formation, demonstrated that the increased size of TCR oligomers was directly responsible for the increased sensitivity of antigen-experienced T cells. Thus, we propose that an "avidity maturation" mechanism underlies T cell antigenic memory.
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Affiliation(s)
- Rashmi Kumar
- Departamento de Biología Celular e Inmunología, Centro Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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