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Kocyła AM, Czogalla A, Wessels I, Rink L, Krężel A. A combined biochemical and cellular approach reveals Zn 2+-dependent hetero- and homodimeric CD4 and Lck assemblies in T cells. Structure 2024; 32:292-303.e7. [PMID: 38157858 DOI: 10.1016/j.str.2023.11.013] [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] [Received: 07/12/2023] [Revised: 10/25/2023] [Accepted: 11/30/2023] [Indexed: 01/03/2024]
Abstract
The CD4 or CD8 co-receptors' interaction with the protein-tyrosine kinase Lck initiates the tyrosine phosphorylation cascade leading to T cell activation. A critical question is: to what extent are co-receptors and Lck coupled? Our contribution concerns Zn2+, indispensable for CD4- and CD8-Lck formation. We combined biochemical and cellular approaches to show that dynamic fluctuations of free Zn2+ in physiological ranges influence Zn(CD4)2 and Zn(CD4)(Lck) species formation and their ratio, although the same Zn(Cys)2(Cys)2 cores. Moreover, we demonstrated that the affinity of Zn2+ to CD4 and CD4-Lck species differs significantly. Increased intracellular free Zn2+ concentration in T cells causes higher CD4 partitioning in the plasma membrane. We additionally found that CD4 palmitoylation decreases the specificity of CD4-Lck formation in the reconstituted membrane model. Our findings help elucidate co-receptor-Lck coupling stoichiometry and demonstrate that intracellular free Zn2+ has a major role in the interplay between CD4 dimers and CD4-Lck assembly.
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Affiliation(s)
- Anna M Kocyła
- Department of Chemical Biology, Faculty of Biotechnology, University of Wroclaw, 50-383 Wroclaw, Poland
| | - Aleksander Czogalla
- Department of Cytobiochemistry, Faculty of Biotechnology, University of Wroclaw, 50-383 Wroclaw, Poland
| | - Inga Wessels
- Institute of Immunology, Faculty of Medicine, RWTH Aachen University, 52074 Aachen, Germany
| | - Lothar Rink
- Institute of Immunology, Faculty of Medicine, RWTH Aachen University, 52074 Aachen, Germany
| | - Artur Krężel
- Department of Chemical Biology, Faculty of Biotechnology, University of Wroclaw, 50-383 Wroclaw, Poland.
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2
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Mørch AM, Bálint Š, Santos AM, Davis SJ, Dustin ML. Coreceptors and TCR Signaling - the Strong and the Weak of It. Front Cell Dev Biol 2020; 8:597627. [PMID: 33178706 PMCID: PMC7596257 DOI: 10.3389/fcell.2020.597627] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 09/28/2020] [Indexed: 12/02/2022] Open
Abstract
The T-cell coreceptors CD4 and CD8 have well-characterized and essential roles in thymic development, but how they contribute to immune responses in the periphery is unclear. Coreceptors strengthen T-cell responses by many orders of magnitude - beyond a million-fold according to some estimates - but the mechanisms underlying these effects are still debated. T-cell receptor (TCR) triggering is initiated by the binding of the TCR to peptide-loaded major histocompatibility complex (pMHC) molecules on the surfaces of other cells. CD4 and CD8 are the only T-cell proteins that bind to the same pMHC ligand as the TCR, and can directly associate with the TCR-phosphorylating kinase Lck. At least three mechanisms have been proposed to explain how coreceptors so profoundly amplify TCR signaling: (1) the Lck recruitment model and (2) the pseudodimer model, both invoked to explain receptor triggering per se, and (3) two-step coreceptor recruitment to partially triggered TCRs leading to signal amplification. More recently it has been suggested that, in addition to initiating or augmenting TCR signaling, coreceptors effect antigen discrimination. But how can any of this be reconciled with TCR signaling occurring in the absence of CD4 or CD8, and with their interactions with pMHC being among the weakest specific protein-protein interactions ever described? Here, we review each theory of coreceptor function in light of the latest structural, biochemical, and functional data. We conclude that the oldest ideas are probably still the best, i.e., that their weak binding to MHC proteins and efficient association with Lck allow coreceptors to amplify weak incipient triggering of the TCR, without comprising TCR specificity.
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Affiliation(s)
- Alexander M. Mørch
- The Kennedy Institute of Rheumatology, University of Oxford, Oxford, United Kingdom
- Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Štefan Bálint
- The Kennedy Institute of Rheumatology, University of Oxford, Oxford, United Kingdom
| | - Ana Mafalda Santos
- Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Simon J. Davis
- Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Michael L. Dustin
- The Kennedy Institute of Rheumatology, University of Oxford, Oxford, United Kingdom
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3
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Padjasek M, Kocyła A, Kluska K, Kerber O, Tran JB, Krężel A. Structural zinc binding sites shaped for greater works: Structure-function relations in classical zinc finger, hook and clasp domains. J Inorg Biochem 2020; 204:110955. [DOI: 10.1016/j.jinorgbio.2019.110955] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 11/08/2019] [Accepted: 12/01/2019] [Indexed: 12/12/2022]
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Junghans V, Hladilkova J, Santos AM, Lund M, Davis SJ, Jönsson P. Hydrodynamic trapping measures the interaction between membrane-associated molecules. Sci Rep 2018; 8:12479. [PMID: 30127338 PMCID: PMC6102267 DOI: 10.1038/s41598-018-30285-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 07/27/2018] [Indexed: 11/27/2022] Open
Abstract
How membrane proteins distribute and behave on the surface of cells depends on the molecules' chemical potential. However, measuring this potential, and how it varies with protein-to-protein distance, has been challenging. Here, we present a method we call hydrodynamic trapping that can achieve this. Our method uses the focused liquid flow from a micropipette to locally accumulate molecules protruding above a lipid membrane. The chemical potential, as well as information about the dimensions of the studied molecule, are obtained by relating the degree of accumulation to the strength of the trap. We have used this method to study four representative proteins, with different height-to-width ratios and molecular properties; from globular streptavidin, to the rod-like immune cell proteins CD2, CD4 and CD45. The data we obtain illustrates how protein shape, glycosylation and flexibility influence the behaviour of membrane proteins, as well as underlining the general applicability of the method.
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Affiliation(s)
| | - Jana Hladilkova
- Department of Chemistry, Lund University, SE-22100, Lund, Sweden
| | - Ana Mafalda Santos
- Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Mikael Lund
- Department of Chemistry, Lund University, SE-22100, Lund, Sweden
| | - Simon J Davis
- Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Peter Jönsson
- Department of Chemistry, Lund University, SE-22100, Lund, Sweden.
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5
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High thioredoxin-1 levels in rheumatoid arthritis patients diminish binding and signalling of the monoclonal antibody Tregalizumab. Clin Transl Immunology 2016; 5:e121. [PMID: 28090323 PMCID: PMC5192061 DOI: 10.1038/cti.2016.69] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 09/21/2016] [Accepted: 10/13/2016] [Indexed: 12/13/2022] Open
Abstract
The humanized non-depleting anti-CD4 monoclonal antibody Tregalizumab (BT-061) is able to selectively activate the suppressive function of regulatory T cells and has been investigated up to phase IIb in clinical trials in patients suffering from rheumatoid arthritis (RA). A pharmacokinetic–pharmacodynamic model based on clinical data from RA and healthy volunteers, which used the cell surface CD4 downmodulation as marker of activity, confirmed a stronger effect in healthy volunteers compared with RA patients. We tried to understand this phenomenon and evaluated the influence of the small oxidoreductase thioredoxin-1 (Trx1). To counteract oxidative stress that is strongly associated with RA pathophysiology, the organism employs Trx1. Therefore, increased expression and secretion of Trx1 is found in the synovial fluid and plasma of RA patients. Moreover, the binding site of Tregalizumab is in close proximity to a disulphide bond in domain 2 (D2) of CD4, which is a known target for a reduction by oxidoreductase Trx1. With the experiments reported herein, we demonstrated that specific reduction of the D2 disulphide bond by Trx1 led to diminished binding of Tregalizumab to recombinant human soluble CD4 and membrane-bound CD4 on T cells. Moreover, we showed that this caused changes in the Tregalizumab-induced CD4 signalling pathway via the lymphocyte-specific protein tyrosine kinase p56Lck and CD4 downmodulation. In summary, we provide evidence that high Trx1 levels in RA patients compared with healthy subjects are a potential reason for diminished binding of Tregalizumab to CD4-positive T cells and offer an explanation for the observed decreased CD4 downmodulation in RA patients in comparison to healthy subjects.
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Parrish HL, Glassman CR, Keenen MM, Deshpande NR, Bronnimann MP, Kuhns MS. A Transmembrane Domain GGxxG Motif in CD4 Contributes to Its Lck-Independent Function but Does Not Mediate CD4 Dimerization. PLoS One 2015; 10:e0132333. [PMID: 26147390 PMCID: PMC4493003 DOI: 10.1371/journal.pone.0132333] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 06/14/2015] [Indexed: 12/24/2022] Open
Abstract
CD4 interactions with class II major histocompatibility complex (MHC) molecules are essential for CD4+ T cell development, activation, and effector functions. While its association with p56lck (Lck), a Src kinase, is important for these functions CD4 also has an Lck-independent role in TCR signaling that is incompletely understood. Here, we identify a conserved GGxxG motif in the CD4 transmembrane domain that is related to the previously described GxxxG motifs of other proteins and predicted to form a flat glycine patch in a transmembrane helix. In other proteins, these patches have been reported to mediate dimerization of transmembrane domains. Here we show that introducing bulky side-chains into this patch (GGxxG to GVxxL) impairs the Lck-independent role of CD4 in T cell activation upon TCR engagement of agonist and weak agonist stimulation. However, using Forster’s Resonance Energy Transfer (FRET), we saw no evidence that these mutations decreased CD4 dimerization either in the unliganded state or upon engagement of pMHC concomitantly with the TCR. This suggests that the CD4 transmembrane domain is either mediating interactions with an unidentified partner, or mediating some other function such as membrane domain localization that is important for its role in T cell activation.
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Affiliation(s)
- Heather L. Parrish
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
| | - Caleb R. Glassman
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
| | - Madeline M. Keenen
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
| | - Neha R. Deshpande
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
- The Arizona Center on Aging, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
| | - Matthew P. Bronnimann
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
| | - Michael S. Kuhns
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
- The Arizona Center on Aging, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
- The BIO-5 Institute, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
- * E-mail:
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Klotzsch E, Stiegler J, Ben-Ishay E, Gaus K. Do mechanical forces contribute to nanoscale membrane organisation in T cells? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:822-9. [PMID: 25447546 DOI: 10.1016/j.bbamcr.2014.10.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 09/26/2014] [Accepted: 10/25/2014] [Indexed: 12/23/2022]
Abstract
Mechanotransduction describes how a cell senses and interacts with its environment. The concept originated in adhesion biology where adhesion receptors, integrins, facilitate force transmission between the extracellular matrix and the intracellular actin cytoskeleton. Indeed, during any adhesive contacts, cells do exert mechanical force. Hence, the probing of the local environment by cells results in mechanical cues that contribute to cellular functions and cell fate decisions such as migration, proliferation, differentiation and apoptosis. On the molecular level, mechanical forces can rearrange proteins laterally within the membrane, regulate their activity by inducing conformational changes and probe the mechanical properties and bond strength of receptor-ligands. From this point of view, it appears surprising that molecular forces have been largely overlooked in membrane organisation and ligand discrimination processes in lymphocytes. During T cell activation, the T cell receptor recognises and distinguishes antigenic from benign endogenous peptides to initiate the reorganisation of membrane proteins into signalling clusters within the immunological synapse. In this review, we asked whether characteristics of fibroblast force sensing could be applied to immune cell antigen recognition and signalling, and outline state-of-the-art experimental strategies for studying forces in the context of membrane organisation. This article is part of a Special Issue entitled: Nanoscale membrane orgainisation and signalling.
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Affiliation(s)
- Enrico Klotzsch
- Centre for Vascular Research, ARC Centre of Excellence in Advanced Molecular Imaging and Australian Centre for Nanomedicine, University of New South Wales, Sydney, Australia.
| | - Johannes Stiegler
- Centre for Vascular Research, ARC Centre of Excellence in Advanced Molecular Imaging and Australian Centre for Nanomedicine, University of New South Wales, Sydney, Australia
| | - Eldad Ben-Ishay
- Centre for Vascular Research, ARC Centre of Excellence in Advanced Molecular Imaging and Australian Centre for Nanomedicine, University of New South Wales, Sydney, Australia
| | - Katharina Gaus
- Centre for Vascular Research, ARC Centre of Excellence in Advanced Molecular Imaging and Australian Centre for Nanomedicine, University of New South Wales, Sydney, Australia.
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8
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Baumgart F, Schütz GJ. Detecting protein association at the T cell plasma membrane. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:791-801. [PMID: 25300585 DOI: 10.1016/j.bbamcr.2014.09.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 09/18/2014] [Accepted: 09/29/2014] [Indexed: 10/24/2022]
Abstract
At the moment, many models on T cell signaling rely on results obtained via rather indirect methodologies, which makes direct comparison and conclusions to the in vivo situation difficult. Recently, a variety of new imaging methods were developed, which have the potential to directly shed light onto the mysteries of protein association at the T cell membrane. While the new modalities are extremely promising, for a broad readership it may be difficult to judge the results, since technological shortcomings are not always obvious. In this review article, we put key questions on the mechanism of protein interactions in the T cell plasma membrane into relation with techniques that allow to address such questions. We discuss applicability of the techniques, their strengths and weaknesses. This article is part of a Special Issue entitled: Nanoscale membrane organisation and signalling.
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Affiliation(s)
- Florian Baumgart
- Vienna University of Technology, Institute for Applied Physics, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria
| | - Gerhard J Schütz
- Vienna University of Technology, Institute for Applied Physics, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria.
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9
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Girard T, Gaucher D, El-Far M, Breton G, Sékaly RP. CD80 and CD86 IgC domains are important for quaternary structure, receptor binding and co-signaling function. Immunol Lett 2014; 161:65-75. [DOI: 10.1016/j.imlet.2014.05.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 05/09/2014] [Indexed: 11/16/2022]
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10
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Cerutti N, Killick M, Jugnarain V, Papathanasopoulos M, Capovilla A. Disulfide reduction in CD4 domain 1 or 2 is essential for interaction with HIV glycoprotein 120 (gp120), which impairs thioredoxin-driven CD4 dimerization. J Biol Chem 2014; 289:10455-10465. [PMID: 24550395 PMCID: PMC4036167 DOI: 10.1074/jbc.m113.539353] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 02/12/2014] [Indexed: 11/06/2022] Open
Abstract
Human CD4 is a membrane-bound glycoprotein expressed on the surface of certain leukocytes, where it plays a key role in the activation of immunostimulatory T cells and acts as the primary receptor for human immunodeficiency virus (HIV) glycoprotein (gp120). Although growing evidence suggests that redox exchange reactions involving CD4 disulfides, potentially catalyzed by cell surface-secreted oxidoreductases such as thioredoxin (Trx) and protein disulfide isomerase, play an essential role in regulating the activity of CD4, their mechanism(s) and biological utility remain incompletely understood. To gain more insights in this regard, we generated a panel of recombinant 2-domain CD4 proteins (2dCD4), including wild-type and Cys/Ala variants, and used these to show that while protein disulfide isomerase has little capacity for 2dCD4 reduction, Trx reduces 2dCD4 highly efficiently, catalyzing the formation of conformationally distinct monomeric 2dCD4 isomers, and a stable, disulfide-linked 2dCD4 dimer. Moreover, we show that HIV gp120 is incapable of binding a fully oxidized, monomeric 2dCD4 in which both domain 1 and 2 disulfides are intact, but binds robustly to reduced counterparts that are the ostensible products of Trx-mediated isomerization. Finally, we demonstrate that Trx-driven dimerization of CD4, a process believed to be critical for the establishment of functional MHCII-TCR-CD4 antigen presentation complexes, is impaired when CD4 is bound to gp120. These observations reinforce the importance of cell surface redox activity for HIV entry and posit the intriguing possibility that one of the many pathogenic effects of HIV may be related to gp120-mediated inhibition of oxidoreductive CD4 isomerization.
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Affiliation(s)
- Nichole Cerutti
- HIV Pathogenesis Research Laboratory, Department of Molecular Medicine and Haematology, University of Witwatersrand Medical School, 7 York Road Parktown, 2193 Johannesburg, South Africa
| | - Mark Killick
- HIV Pathogenesis Research Laboratory, Department of Molecular Medicine and Haematology, University of Witwatersrand Medical School, 7 York Road Parktown, 2193 Johannesburg, South Africa
| | - Vinesh Jugnarain
- HIV Pathogenesis Research Laboratory, Department of Molecular Medicine and Haematology, University of Witwatersrand Medical School, 7 York Road Parktown, 2193 Johannesburg, South Africa
| | - Maria Papathanasopoulos
- HIV Pathogenesis Research Laboratory, Department of Molecular Medicine and Haematology, University of Witwatersrand Medical School, 7 York Road Parktown, 2193 Johannesburg, South Africa
| | - Alexio Capovilla
- HIV Pathogenesis Research Laboratory, Department of Molecular Medicine and Haematology, University of Witwatersrand Medical School, 7 York Road Parktown, 2193 Johannesburg, South Africa.
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Interaction with cellular CD4 exposes HIV-1 envelope epitopes targeted by antibody-dependent cell-mediated cytotoxicity. J Virol 2013; 88:2633-44. [PMID: 24352444 DOI: 10.1128/jvi.03230-13] [Citation(s) in RCA: 217] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Anti-HIV-1 envelope glycoprotein (Env) antibodies without broadly neutralizing activity correlated with protection in the RV144 clinical trial, stimulating interest in other protective mechanisms involving antibodies, such as antibody-dependent cell-mediated cytotoxicity (ADCC). Env epitopes targeted by many antibodies effective at mediating ADCC are poorly exposed on the unliganded Env trimer. Here we investigated the mechanism of exposure of ADCC epitopes on Env and showed that binding of Env and CD4 within the same HIV-1-infected cell effectively exposes these epitopes. Env capacity to transit to the CD4-bound conformation is required for ADCC epitope exposure. Importantly, cell surface CD4 downregulation by Nef and Vpu accessory proteins and Vpu-mediated BST-2 antagonism modulate exposure of ADCC-mediating epitopes and reduce the susceptibility of infected cells to this effector function in vitro. Significantly, Env conformational changes induced by cell surface CD4 are conserved among Env from HIV-1 and HIV-2/SIVmac lineages. Altogether, our observations describe a highly conserved mechanism required to expose ADCC epitopes that might help explain the evolutionary advantage of downregulation of cell surface CD4 by the HIV-1 Vpu and Nef proteins. IMPORTANCE HIV-1 envelope epitopes targeted by many antibodies effective at mediating antibody-dependent cell-mediated cytotoxicity (ADCC) are poorly exposed on the unliganded envelope trimer. Here we investigated the mechanism of exposure of these epitopes and found that envelope interaction with the HIV-1 CD4 receptor is required to expose some of these epitopes. Moreover, our results suggest that HIV-1 CD4 downregulation might help avoid the killing of HIV-1-infected cells by this immune mechanism.
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Li Y, Yin Y, Mariuzza RA. Structural and biophysical insights into the role of CD4 and CD8 in T cell activation. Front Immunol 2013; 4:206. [PMID: 23885256 PMCID: PMC3717711 DOI: 10.3389/fimmu.2013.00206] [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: 05/07/2013] [Accepted: 07/08/2013] [Indexed: 11/19/2022] Open
Abstract
T cell receptors (TCRs) recognize peptides presented by MHC molecules (pMHC) on an antigen-presenting cell (APC) to discriminate foreign from self-antigens and initiate adaptive immune responses. In addition, T cell activation generally requires binding of this same pMHC to a CD4 or CD8 co-receptor, resulting in assembly of a TCR–pMHC–CD4 or TCR–pMHC–CD8 complex and recruitment of Lck via its association with the co-receptor. Here we review structural and biophysical studies of CD4 and CD8 interactions with MHC molecules and TCR–pMHC complexes. Crystal structures have been determined of CD8αα and CD8αβ in complex with MHC class I, of CD4 bound to MHC class II, and of a complete TCR–pMHC–CD4 ternary complex. Additionally, the binding of these co-receptors to pMHC and TCR–pMHC ligands has been investigated both in solution and in situ at the T cell–APC interface. Together, these studies have provided key insights into the role of CD4 and CD8 in T cell activation, and into how these co-receptors focus TCR on MHC to guide TCR docking on pMHC during thymic T cell selection.
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Affiliation(s)
- Yili Li
- W. M. Keck Laboratory for Structural Biology, Institute for Bioscience and Biotechnology Research, University of Maryland , Rockville, MD , USA ; Department of Cell Biology and Molecular Genetics, University of Maryland , College Park, MD , USA
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13
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Kuhns MS, Davis MM. TCR Signaling Emerges from the Sum of Many Parts. Front Immunol 2012; 3:159. [PMID: 22737151 PMCID: PMC3381686 DOI: 10.3389/fimmu.2012.00159] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Accepted: 05/27/2012] [Indexed: 11/30/2022] Open
Abstract
“How does T cell receptor signaling begin?” Answering this question requires an understanding of how the parts of the molecular machinery that mediates this process fit and work together. Ultimately this molecular architecture must (i) trigger the relay of information from the TCR-pMHC interface to the signaling substrates of the CD3 molecules and (ii) bring the kinases that modify these substrates in close proximity to interact, initiate, and sustain signaling. In this contribution we will discuss advances of the last decade that have increased our understanding of the complex machinery and interactions that underlie this type of signaling.
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Affiliation(s)
- Michael S Kuhns
- Department of Immunobiology, The University of Arizona College of Medicine Tucson, AZ, USA
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Jaron-Mendelson M, Yossef R, Appel MY, Zilka A, Hadad U, Afergan F, Rosental B, Engel S, Nedvetzki S, Braiman A, Porgador A. Dimerization of NKp46 Receptor Is Essential for NKp46-Mediated Lysis: Characterization of the Dimerization Site by Epitope Mapping. THE JOURNAL OF IMMUNOLOGY 2012; 188:6165-74. [DOI: 10.4049/jimmunol.1102496] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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15
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Fournier M, Peyrou M, Bourgoin L, Maeder C, Tchou I, Foti M. CD4 dimerization requires two cysteines in the cytoplasmic domain of the molecule and occurs in microdomains distinct from lipid rafts. Mol Immunol 2010; 47:2594-603. [DOI: 10.1016/j.molimm.2010.06.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 05/06/2010] [Accepted: 06/21/2010] [Indexed: 01/27/2023]
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16
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Abstract
BACKGROUND It is hypothesized that psoriasis is an autoimmune disease. The most recent therapeutic approach that proved to be more effective than earlier methods of treatment is the use of mAb/fusion proteins. Efforts nowadays are focused on investigating the antipsoriatic affect of small molecules that can be administered orally, some of which are capable of entering cells, and being selective in targeting intracellular pathways. OBJECTIVE Preclinical patented small molecules that are recommended for the treatment of psoriasis are reviewed. Emphasis is placed on their mechanism of action. METHODS http://ep.espacenet.com/ , Pubmed, Scopus and Google websites were the main sources used for the patented small molecule search. A number of patents were poorly described and difficulties were faced in trying to figure out the patentee(s) explanation. Moreover, most patents were recommended for the treatment of a number of autoimmune diseases and cancer, and not only for psoriasis. RESULTS/CONCLUSIONS Small molecules that inhibit the activation of T lymphocytes, leukocyte trafficking, leukotriene activity/production and angiogenesis, and promote apoptosis have been patented. Small molecules that have been patented for the treatment of other autoimmune diseases and could be used for treating psoriasis are described. Moreover, other possible mechanistic approaches using small molecules are discussed.
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Affiliation(s)
- Alexander M Abdelnoor
- American University of Beirut, Department of Microbiology & Immunology, Riad el-Solh, Beirut 1107 2020, Lebanon.
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17
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Detection of Homo- or Hetero-Association of Doks by Fluorescence Resonance Energy Transfer in Living Cells. Mol Imaging Biol 2008; 11:188-94. [DOI: 10.1007/s11307-008-0189-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2008] [Revised: 06/24/2008] [Accepted: 07/24/2008] [Indexed: 10/21/2022]
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18
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Mantei A, Rutz S, Janke M, Kirchhoff D, Jung U, Patzel V, Vogel U, Rudel T, Andreou I, Weber M, Scheffold A. siRNA stabilization prolongs gene knockdown in primary T lymphocytes. Eur J Immunol 2008; 38:2616-25. [DOI: 10.1002/eji.200738075] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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19
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DeMond AL, Groves JT. Interrogating the T cell synapse with patterned surfaces and photoactivated proteins. Curr Opin Immunol 2007; 19:722-7. [PMID: 17703931 DOI: 10.1016/j.coi.2007.07.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Revised: 06/06/2007] [Accepted: 07/04/2007] [Indexed: 10/22/2022]
Abstract
The immunological synapse is a site rich in spatially modulated signaling cascades. The importance of spatial organization in intercellular signal transduction has prompted much recent interest in techniques to control the localization of cell-surface signaling molecules to investigate synaptic signaling. Photoactivation, patterning, and mechanical constraint of surface-associated molecules are three prominent examples of such techniques. Recent results have demonstrated the effectiveness of these techniques as tools to investigate the mechanisms of immune synapse assembly and synaptic signaling.
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Treanor B, Batista FD. Mechanistic insight into lymphocyte activation through quantitative imaging and theoretical modelling. Curr Opin Immunol 2007; 19:476-83. [PMID: 17659866 DOI: 10.1016/j.coi.2007.05.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Accepted: 05/16/2007] [Indexed: 11/18/2022]
Abstract
Increasingly, it is apparent that in order to understand the complexity of immunosurveillance at the cell-cell junction, quantitative analysis at the single cell level is necessary. The visualisation of the large-scale rearrangement of proteins characterising what is known as the immunological synapse (IS) was an important discovery shaping our understanding of the events occurring during immune recognition. The use of supported planar bilayers and geometrically designed substrates combined with advanced imaging techniques such as total internal reflection fluorescence (TIRF) and Förster resonance energy transfer (FRET) has provided insight into the spatio-temporal dynamics of receptor signalling and the role of receptor trafficking in regulating cell signalling. Theoretical modelling will play a key role in the integration of such quantitative data providing mechanistic insight into lymphocyte activation.
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Affiliation(s)
- Bebhinn Treanor
- Lymphocyte Interaction Laboratory, London Research Institute, Cancer Research UK, 44 Lincoln's Inn Fields, London WC2A 3PX, UK.
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Bourgeois R, Mercier J, Paquette-Brooks I, Cohen ÉA. Association between disruption of CD4 receptor dimerization and increased human immunodeficiency virus type 1 entry. Retrovirology 2006; 3:31. [PMID: 16762062 PMCID: PMC1524797 DOI: 10.1186/1742-4690-3-31] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Accepted: 06/08/2006] [Indexed: 11/12/2022] Open
Abstract
Background Human immunodeficiency virus (HIV) enters target cells by a membrane fusion process that involves a series of sequential interactions between its envelope glycoproteins, the CD4 receptor and CXCR4/CCR5 coreceptors. CD4 molecules are expressed at the cell surface of lymphocytes and monocytes mainly as monomers, but basal levels of CD4 dimers are also present at the cell surface of these cells. Previous evidence indicates that the membrane distal and proximal extracellular domains of CD4, respectively D1 and D4, are involved in receptor dimerization. Results Here, we have used A201 cell lines expressing two CD4 mutants, CD4-E91K, E92K (D1 mutant) and CD4-Q344E (D4 mutant), harboring dimerization defects to analyze the role of CD4 dimerization in HIV-1 entry. Using entry assays based on β-lactamase-Vpr or luciferase reporter activities, as well as virus encoding envelope glycoproteins derived from primary or laboratory-adapted strains, we obtained evidence suggesting an association between disruption of CD4 dimerization and increased viral entry efficiency. Conclusion Taken together, our results suggest that monomeric forms of CD4 are preferentially used by HIV-1 to gain entry into target cells, thus implying that the dimer/monomer ratio at the cell surface of HIV-1 target cells may modulate the efficiency of HIV-1 entry.
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Affiliation(s)
- Rachel Bourgeois
- Department of Microbiology and Immunology, Université de Montréal, Montreal, Quebec, Canada
| | - Johanne Mercier
- Laboratory of Human Retrovirology, Institut de Recherches Cliniques de Montréal, Montreal, Quebec, Canada
| | - Isabelle Paquette-Brooks
- Laboratory of Human Retrovirology, Institut de Recherches Cliniques de Montréal, Montreal, Quebec, Canada
| | - Éric A Cohen
- Department of Microbiology and Immunology, Université de Montréal, Montreal, Quebec, Canada
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