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Philips EA, Liu J, Kvalvaag A, Mørch AM, Tocheva AS, Ng C, Liang H, Ahearn IM, Pan R, Luo CC, Leithner A, Qin Z, Zhou Y, Garcia-España A, Mor A, Littman DR, Dustin ML, Wang J, Kong XP. Transmembrane domain-driven PD-1 dimers mediate T cell inhibition. Sci Immunol 2024; 9:eade6256. [PMID: 38457513 PMCID: PMC11166110 DOI: 10.1126/sciimmunol.ade6256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 02/15/2024] [Indexed: 03/10/2024]
Abstract
Programmed cell death-1 (PD-1) is a potent immune checkpoint receptor on T lymphocytes. Upon engagement by its ligands, PD-L1 or PD-L2, PD-1 inhibits T cell activation and can promote immune tolerance. Antagonism of PD-1 signaling has proven effective in cancer immunotherapy, and conversely, agonists of the receptor may have a role in treating autoimmune disease. Some immune receptors function as dimers, but PD-1 has been considered monomeric. Here, we show that PD-1 and its ligands form dimers as a consequence of transmembrane domain interactions and that propensity for dimerization correlates with the ability of PD-1 to inhibit immune responses, antitumor immunity, cytotoxic T cell function, and autoimmune tissue destruction. These observations contribute to our understanding of the PD-1 axis and how it can potentially be manipulated for improved treatment of cancer and autoimmune diseases.
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Affiliation(s)
- Elliot A. Philips
- Departments of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Jia Liu
- Department of Pathology, New York University Grossman School of Medicine, New York, NY 10016, USA
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Health, New York, NY 10016, USA
| | - Audun Kvalvaag
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
- Institute for Cancer Research, Oslo University Hospital, Oslo, 0379, Norway
| | - Alexander M. Mørch
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
| | - Anna S. Tocheva
- Department of Genetics and Genomic Sciences, Icahn School of Medicine, New York, NY 10029, USA
| | - Charles Ng
- Department of Cell Biology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Hong Liang
- Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Ian M. Ahearn
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Health, New York, NY 10016, USA
| | - Ruimin Pan
- Departments of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Christina C. Luo
- Departments of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Alexander Leithner
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
| | - Zhihua Qin
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Health, New York, NY 10016, USA
| | - Yong Zhou
- Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Antonio Garcia-España
- Research Unit, Hospital Universitari de Tarragona Joan XXIII, Institut d’Investigació Sanitària Pere Virgili, Universitat Rovira i Virgili, Tarragona, Spain
| | - Adam Mor
- Columbia Center for Translational Immunology, Columbia University Medical Center, New York, NY 10032, USA
| | - Dan R. Littman
- Department of Cell Biology, New York University Grossman School of Medicine, New York, NY 10016, USA
- Howard Hughes Medical Institute, New York, NY 10016, USA
| | - Michael L. Dustin
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
| | - Jun Wang
- Department of Pathology, New York University Grossman School of Medicine, New York, NY 10016, USA
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Health, New York, NY 10016, USA
| | - Xiang-Peng Kong
- Departments of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
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2
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Rudd CE. How the Discovery of the CD4/CD8-p56 lck Complexes Changed Immunology and Immunotherapy. Front Cell Dev Biol 2021; 9:626095. [PMID: 33791292 PMCID: PMC8005572 DOI: 10.3389/fcell.2021.626095] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 01/11/2021] [Indexed: 12/22/2022] Open
Abstract
The past 25 years have seen enormous progress in uncovering the receptors and signaling mechanisms on T-cells that activate their various effecter functions. Until the late 1980s, most studies on T-cells had focused on the influx of calcium and the levels of cAMP/GMP in T-cells. My laboratory then uncovered the interaction of CD4 and CD8 co-receptors with the protein-tyrosine kinase p56lck which are now widely accepted as the initiators of the tyrosine phosphorylation cascade leading to T-cell activation. The finding explained how immune recognition receptors expressed by many immune cells, which lack intrinsic catalytic activity, can transduce activation signals via non-covalent association with non-receptor tyrosine kinases. The discovery also established the concept that a protein tyrosine phosphorylation cascade operated in T-cells. In this vein, we and others then showed that the CD4- and CD8-p56lck complexes phosphorylate the TCR complexes which led to the identification of other protein-tyrosine kinases such as ZAP-70 and an array of substrates that are now central to studies in T-cell immunity. Other receptors such as B-cell receptor, Fc receptors and others were also subsequently found to use src kinases to control cell growth. In T-cells, p56lck driven phosphorylation targets include co-receptors such as CD28 and CTLA-4 and immune cell-specific adaptor proteins such as LAT and SLP-76 which act to integrate signals proximal to surface receptors. CD4/CD8-p56lck regulated events in T-cells include intracellular calcium mobilization, integrin activation and the induction of transcription factors for gene expression. Lastly, the identification of the targets of p56lck in the TCR and CD28 provided the framework for the development of chimeric antigen receptor (CAR) therapy in the treatment of cancer. In this review, I outline a history of the development of events that led to the development of the "TCR signaling paradigm" and its implications to immunology and immunotherapy.
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Affiliation(s)
- Christopher E. Rudd
- Division of Immunology-Oncology, Centre de Recherche Hôpital Maisonneuve-Rosemont (CR-HMR), Montreal, QC, Canada
- Department of Microbiology, Infection and Immunology, Faculty of Medicine, Universite de Montreal, Montreal, QC, Canada
- Division of Experimental Medicine, Department of Medicine, McGill University Health Center, McGill University, Montreal, QC, Canada
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3
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Llorente García I, Marsh M. A biophysical perspective on receptor-mediated virus entry with a focus on HIV. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2020; 1862:183158. [PMID: 31863725 PMCID: PMC7156917 DOI: 10.1016/j.bbamem.2019.183158] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 12/12/2019] [Accepted: 12/13/2019] [Indexed: 12/14/2022]
Abstract
As part of their entry and infection strategy, viruses interact with specific receptor molecules expressed on the surface of target cells. The efficiency and kinetics of the virus-receptor interactions required for a virus to productively infect a cell is determined by the biophysical properties of the receptors, which are in turn influenced by the receptors' plasma membrane (PM) environments. Currently, little is known about the biophysical properties of these receptor molecules or their engagement during virus binding and entry. Here we review virus-receptor interactions focusing on the human immunodeficiency virus type 1 (HIV), the etiological agent of acquired immunodeficiency syndrome (AIDS), as a model system. HIV is one of the best characterised enveloped viruses, with the identity, roles and structure of the key molecules required for infection well established. We review current knowledge of receptor-mediated HIV entry, addressing the properties of the HIV cell-surface receptors, the techniques used to measure these properties, and the macromolecular interactions and events required for virus entry. We discuss some of the key biophysical principles underlying receptor-mediated virus entry and attempt to interpret the available data in the context of biophysical mechanisms. We also highlight crucial outstanding questions and consider how new tools might be applied to advance understanding of the biophysical properties of viral receptors and the dynamic events leading to virus entry.
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Affiliation(s)
| | - Mark Marsh
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
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4
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Glatzová D, Cebecauer M. Dual Role of CD4 in Peripheral T Lymphocytes. Front Immunol 2019; 10:618. [PMID: 31001252 PMCID: PMC6454155 DOI: 10.3389/fimmu.2019.00618] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/08/2019] [Indexed: 01/07/2023] Open
Abstract
The interaction of T-cell receptors (TCRs) with self- and non-self-peptides in the major histocompatibility complex (MHC) stimulates crucial signaling events, which in turn can activate T lymphocytes. A variety of accessory molecules further modulate T-cell signaling. Of these, the CD4 and CD8 coreceptors make the most critical contributions to T cell sensitivity in vivo. Whereas, CD4 function in T cell development is well-characterized, its role in peripheral T cells remains incompletely understood. It was originally suggested that CD4 stabilizes weak interactions between TCRs and peptides in the MHC and delivers Lck kinases to that complex. The results of numerous experiments support the latter role, indicating that the CD4-Lck complex accelerates TCR-triggered signaling and controls the availability of the kinase for TCR in the absence of the ligand. On the other hand, extremely low affinity of CD4 for MHC rules out its ability to stabilize the receptor-ligand complex. In this review, we summarize the current knowledge on CD4 in T cells, with a special emphasis on the spatio-temporal organization of early signaling events and the relevance for CD4 function. We further highlight the capacity of CD4 to interact with the MHC in the absence of TCR. It drives the adhesion of T cells to the cells that express the MHC. This process is facilitated by the CD4 accumulation in the tips of microvilli on the surface of unstimulated T cells. Based on these observations, we suggest an alternative model of CD4 role in T-cell activation.
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Affiliation(s)
- Daniela Glatzová
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
- Laboratory of Leukocyte Signaling, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Marek Cebecauer
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
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5
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Moolla N, Killick M, Papathanasopoulos M, Capovilla A. Thioredoxin (Trx1) regulates CD4 membrane domain localization and is required for efficient CD4-dependent HIV-1 entry. Biochim Biophys Acta Gen Subj 2016; 1860:1854-63. [PMID: 27233453 DOI: 10.1016/j.bbagen.2016.05.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 05/12/2016] [Accepted: 05/21/2016] [Indexed: 11/25/2022]
Abstract
BACKGROUND CD4 is a glycoprotein expressed on the surfaces of certain immune cells. On lymphocytes, an important function of CD4 is to co-engage Major Histocompatibility Complex (MHC) molecules with the T Cell Receptor (TCR), a process that is essential for antigen-specific activation of T cells. CD4 localizes dynamically into distinct membrane microdomains, an important feature of its immunoregulatory function that has also been shown to influence the efficiency of HIV replication. However, the mechanism by which CD4 localization is regulated and the biological significance of this is incompletely understood. METHODS In this study, we used confocal microscopy, density-gradient centrifugation and flow cytometry to analyze dynamic redox-dependent effects on CD4 membrane domain localization. RESULTS Blocking cell surface redox exchanges with both a membrane-impermeable sulfhydryl blocker (DTNB) and specific antibody inhibitors of Thioredoxin-1 (Trx1) induces translocation of CD4 into detergent-resistant membrane domains (DRM). In contrast, Trx1 inactivation does not change the localization of the chemokine receptor CCR5, suggesting that this effect is targeted. Moreover, DTNB treatment and Trx1 depletion coincide with strong inhibition of CD4-dependent HIV entry, but only moderate reductions in the infectivity of a CD4-independent HIV pseudovirion. CONCLUSIONS Changes in the extracellular redox environment, potentially mediated by allosteric consequences of functional disulfide bond oxidoreduction, may represent a signal for translocation of CD4 into DRM clusters, and this sequestration, another potential mechanism by which the anti-HIV effects of cell surface oxidoreductase inhibition are exerted. GENERAL SIGNIFICANCE Extracellular redox conditions may regulate CD4 function by potentiating changes in its membrane domain localization.
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Affiliation(s)
- Naazneen Moolla
- HIV Pathogenesis Research Unit, Department of Molecular Medicine and Haematology, University of the Witwatersrand, Faculty of Health Sciences, 7 York Road Parktown, 2193 Johannesburg, South Africa
| | - Mark Killick
- HIV Pathogenesis Research Unit, Department of Molecular Medicine and Haematology, University of the Witwatersrand, Faculty of Health Sciences, 7 York Road Parktown, 2193 Johannesburg, South Africa
| | - Maria Papathanasopoulos
- HIV Pathogenesis Research Unit, Department of Molecular Medicine and Haematology, University of the Witwatersrand, Faculty of Health Sciences, 7 York Road Parktown, 2193 Johannesburg, South Africa
| | - Alexio Capovilla
- HIV Pathogenesis Research Unit, Department of Molecular Medicine and Haematology, University of the Witwatersrand, Faculty of Health Sciences, 7 York Road Parktown, 2193 Johannesburg, South Africa.
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6
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Owen GR, Channell JA, Forsyth VT, Haertlein M, Mitchell EP, Capovilla A, Papathanasopoulos M, Cerutti NM. Human CD4 Metastability Is a Function of the Allosteric Disulfide Bond in Domain 2. Biochemistry 2016; 55:2227-37. [DOI: 10.1021/acs.biochem.6b00154] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gavin R. Owen
- HIV
Pathogenesis Research Unit, Department of Molecular Medicine and Haematology,
Faculty of Health Sciences, University of the Witwatersrand, 7
York Road, Parktown, 2193, Johannesburg, South Africa
| | - Jennifer A. Channell
- Faculty
of Natural Sciences, Keele University, Keele, Staffordshire ST5 5BG, United Kingdom
- Life
Sciences Group, Institut Laue-Langevin, 71 Avenue des Martyrs, 38042, Grenoble, France
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38042, Grenoble, France
| | - V. Trevor Forsyth
- Faculty
of Natural Sciences, Keele University, Keele, Staffordshire ST5 5BG, United Kingdom
- Life
Sciences Group, Institut Laue-Langevin, 71 Avenue des Martyrs, 38042, Grenoble, France
| | - Michael Haertlein
- Life
Sciences Group, Institut Laue-Langevin, 71 Avenue des Martyrs, 38042, Grenoble, France
| | - Edward P. Mitchell
- Faculty
of Natural Sciences, Keele University, Keele, Staffordshire ST5 5BG, United Kingdom
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38042, Grenoble, France
| | - Alexio Capovilla
- HIV
Pathogenesis Research Unit, Department of Molecular Medicine and Haematology,
Faculty of Health Sciences, University of the Witwatersrand, 7
York Road, Parktown, 2193, Johannesburg, South Africa
| | - Maria Papathanasopoulos
- HIV
Pathogenesis Research Unit, Department of Molecular Medicine and Haematology,
Faculty of Health Sciences, University of the Witwatersrand, 7
York Road, Parktown, 2193, Johannesburg, South Africa
| | - Nichole M. Cerutti
- HIV
Pathogenesis Research Unit, Department of Molecular Medicine and Haematology,
Faculty of Health Sciences, University of the Witwatersrand, 7
York Road, Parktown, 2193, Johannesburg, South Africa
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7
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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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8
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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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9
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Stegmann M, Metcalfe C, Barclay AN. Immunoregulation through membrane proteins modified by reducing conditions induced by immune reactions. Eur J Immunol 2013; 43:15-21. [PMID: 23233323 PMCID: PMC7163605 DOI: 10.1002/eji.201242849] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 10/22/2012] [Accepted: 12/05/2012] [Indexed: 01/19/2023]
Abstract
Selected disulfide bonds in membrane proteins are labile and are thus susceptible to changes in redox potential and/or the presence of thiol isomerase enzymes. Modification of these disulfide bonds can lead to conformational changes of the protein that in turn may alter protein activity and function. This occurs in the entry of several enveloped viruses into their host cells, e.g. HIV, hepatitis C virus and Newcastle disease virus. Labile disulfide bonds are also important in platelet activation, cytokine signalling and in a variety of diseases including cancer and arthritis. In this review we will concentrate on recent advances in understanding the conditions that lead to disulfide bond reduction in membrane proteins and their effects in regulating immune function.
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Affiliation(s)
- Monika Stegmann
- Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, United Kingdom
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10
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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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11
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Baker AM, Saulière A, Gaibelet G, Lagane B, Mazères S, Fourage M, Bachelerie F, Salomé L, Lopez A, Dumas F. CD4 interacts constitutively with multiple CCR5 at the plasma membrane of living cells. A fluorescence recovery after photobleaching at variable radii approach. J Biol Chem 2007; 282:35163-8. [PMID: 17855336 DOI: 10.1074/jbc.m705617200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The entry of human immunodeficiency virus into target cells requires successive interactions of the viral envelope glycoprotein gp120 with CD4 and the chemokine receptors CCR5 or CXCR4. We previously demonstrated, by Förster resonance energy transfer experiments, the constitutive association of CD4 and CCR5 at the surface of living cells. We therefore speculated that this interaction may correlate with compartmentalization of CD4 and CCR5 within the plasma membrane. Here, we characterize the lateral distribution, the dynamics, and the stoichiometry of these receptors in living cells stably expressing CD4 and/or CCR5 by means of fluorescence recovery after photobleaching at variable radii experiments. We found that (i) these receptors expressed alone are confined into 1-microm-sized domains, (ii) CD4-CCR5 associations occur outside and inside smaller domains, and (iii) these interactions involve multiple CCR5 molecules per CD4.
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Affiliation(s)
- Aurélie-Marie Baker
- Institut de Pharmacologie et Biologie Structurale, UMR CNRS-Université Paul Sabatier 5089, 205 Route de Narbonne, 31062 Toulouse cedex, France
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12
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Filatov AV, Krotov GI, Zgoda VG, Volkov Y. Fluorescent immunoprecipitation analysis of cell surface proteins: A methodology compatible with mass-spectrometry. J Immunol Methods 2007; 319:21-33. [PMID: 17098248 DOI: 10.1016/j.jim.2006.09.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2006] [Revised: 05/22/2006] [Accepted: 09/20/2006] [Indexed: 11/30/2022]
Abstract
Radiolabelling and biotinylation of cell proteins followed by immunoprecipitation is a common procedure for biochemical characterization of cell-surface antigens recognized by monoclonal antibodies. Here we present a new method of cell labelling with fluorescent dyes followed by immunoprecipitation and SDS-PAGE with subsequent detection of specific bands by fluorescence imaging devices. Fluorescent immunoprecipitation analysis (FIPA) of cell surface proteins is a fast and sensitive alternative to conventional immunoprecipitation methods, eliminating the need to employ radioactive or biotin labels. The proposed method is compatible with mass spectrometry analysis and permits the identification of immunoprecipitated proteins.
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13
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Lynch GW, Turville S, Carter B, Sloane AJ, Chan A, Muljadi N, Li S, Low L, Armati P, Raison R, Zoellner H, Williamson P, Cunningham A, Church WB. Marked differences in the structures and protein associations of lymphocyte and monocyte CD4: resolution of a novel CD4 isoform. Immunol Cell Biol 2006; 84:154-65. [PMID: 16519733 DOI: 10.1111/j.1440-1711.2005.01403.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The structures, molecular interactions and functions of CD4 in a subset of T lymphocytes have been well characterized. The CD4 receptors of other cell types have, however, been poorly documented. We have previously shown that lymphocytes and monocytes/macrophages differ in their expression of CD4 monomers and dimers. In the present study, we have shown further significant differences. Variability in the blocking of CD4 mAb binding by sulfated polyanions indicated differences in exofacial CD4 structures. In contrast to the well-documented 55 kDa monomers in lymphocytic cells, monocytic cells were found to coexpress two monomer isoforms: the 55 kDa form and a novel 59 kDa species. Experimental uncoupling of CD4 disulfides indicated that the oxidized 55 kDa monomer could be converted to the 59 kDa form. This was achieved by chemical reduction of purified native or recombinant CD4, or in cell transfection experiments by mutation of cysteine to alanine in domain 1 (D1) (Cys16 or Cys84) and in domain 4 (D4) (Cys303 or Cys345). All of these modifications promote CD4 distension on SDS-PAGE analysis and indicate that, when CD4 inter-beta-sheet disulfides in the D1 and D4 Ig folds are disrupted, there is an unravelling of the oxidized form to an extended 59 kDa unfolded state. We hypothesize that this may be a transition-state, structural-intermediate in the formation of disulfide-linked homodimers. Also identified were CD4-tyrosine kinase dissimilarities in which lymphocyte CD4 associated with Lck, but monocyte CD4 associated with HcK. These findings show that there is complex heterogeneity in structures and interactions in the CD4 of T lymphocytes and monocytes.
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Affiliation(s)
- Garry W Lynch
- HIV-Protein Interactions Laboratory, Westmead Millennium Institute, Westmead, Australia.
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14
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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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15
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Moldovan MC, Sabbagh L, Breton G, Sékaly RP, Krummel MF. Triggering of T cell activation via CD4 dimers. THE JOURNAL OF IMMUNOLOGY 2006; 176:5438-45. [PMID: 16622011 DOI: 10.4049/jimmunol.176.9.5438] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The onset of activation in Th cells is triggered by localized co-engagement of TCRs and the coreceptor CD4. A CD4 crystal suggested that CD4 may form dimers in some circumstances. In this study, we use live-cell fluorescence resonance energy transfer imaging to demonstrate that CD4 dimers are present at a basal level on the cell surface and accumulate at the synapse. Mechanistically, we reveal two conditions under which dimers are highly relevant. First, CD4 dimers are more proficient in mediating prolonged cell contacts with APCs in the presence or absence of Ag. This is consistent with a model whereby the dimer functions to increase T-APC avidity. Second, we show that dimer mutations result in an increased level of an inactive lckTyr(505) bound to the CD4 molecule relative to dimer-competent CD4. We also find a consistent defect in signaling onset in these cells. This supports a role for CD4 dimerization in maintaining active signaling machinery. We suggest that modulation of the dimer/monomer ratio may permit tuning of activation thresholds during initial engagement.
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16
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Maekawa A, Schmidt B, Fazekas de St Groth B, Sanejouand YH, Hogg PJ. Evidence for a Domain-Swapped CD4 Dimer as the Coreceptor for Binding to Class II MHC. THE JOURNAL OF IMMUNOLOGY 2006; 176:6873-8. [PMID: 16709847 DOI: 10.4049/jimmunol.176.11.6873] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
CD4 is a coreceptor for binding of T cells to APC and the primary receptor for HIV. The disulfide bond in the second extracellular domain (D2) of CD4 is reduced on the cell surface, which leads to formation of disulfide-linked homodimers. A large conformational change must take place in D2 to allow for formation of the disulfide-linked dimer. Domain swapping of D2 is the most likely candidate for the conformational change leading to formation of two disulfide-bonds between Cys130 in one monomer and Cys159 in the other one. Mild reduction of the extracellular part of CD4 resulted in formation of disulfide-linked dimers, which supports the domain-swapped model. The functional significance of dimer formation for coreceptor function was tested using cells expressing wild-type or disulfide-bond mutant CD4. Eliminating the D2 disulfide bond markedly impaired CD4's coreceptor function. Modeling of the complex of the TCR and domain-swapped CD4 dimer bound to class II MHC and Ag supports the domain-swapped dimer as the immune coreceptor. The known involvement of D4 residues Lys318 and Gln344 in dimer formation is also accommodated by this model. These findings imply that disulfide-linked dimeric CD4 is the preferred coreceptor for binding to APC.
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Affiliation(s)
- Akiko Maekawa
- Centre for Vascular Research, University of New South Wales, Sydney, Australia
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17
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Furuta RA, Nishikawa M, Fujisawa JI. Real-time analysis of human immunodeficiency virus type 1 Env-mediated membrane fusion by fluorescence resonance energy transfer. Microbes Infect 2006; 8:520-32. [PMID: 16300985 DOI: 10.1016/j.micinf.2005.08.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2005] [Revised: 08/12/2005] [Accepted: 08/16/2005] [Indexed: 10/25/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env)-mediated membrane fusion occurs as a sequence of events that is triggered by CD4 binding to the Env gp120 subunit. In this study, we analyzed the dynamics of Env-mediated membrane fusion at the single-cell level using fluorescent fusion proteins and confocal laser fluorescent microscopy. Either enhanced cyan or yellow fluorescent protein (CFP and YFP, respectively) was fused to the end of the cytoplasmic regions of the HIV-1 receptors (CD4 and CCR5) and Env proteins. Real-time imaging of membrane fusion mediated by these recombinant proteins revealed that the kinetics of fusion in our system was faster than that previously reported. Analysis of the receptor interaction by fluorescence resonance energy transfer (FRET) at the single-cell level demonstrated a tendency for oligomerization of CD4-CD4, but not of CD4-CCR5, in the absence of Env-expressing cells. However, when Env-expressing cells attached to the receptor cells, FRET produced by CD4-CCR5 interaction was increased; the FRET intensity began to decline before the formation of the fusion pore. These changes in FRET may represent the temporal association of these receptors, triggered by gp120 binding, and their dissociation during the formation of the fusion pore. In addition, the FRET analysis of receptor interactions in the presence of fusion inhibitors showed that not only inhibitors acting on CCR5 but also the gp41-derived peptide T-20 interfered with CD4-CCR5 interaction during fusion. These data suggest that T-20 could affect the formation of Env-receptors complexes during the membrane fusion.
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Affiliation(s)
- Rika A Furuta
- Department of Microbiology, Kansai Medical University, 15-10 Fumizono-cho, Moriguchi, Osaka 570-8506, Japan
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18
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Chang MI, Panorchan P, Dobrowsky TM, Tseng Y, Wirtz D. Single-molecule analysis of human immunodeficiency virus type 1 gp120-receptor interactions in living cells. J Virol 2006; 79:14748-55. [PMID: 16282475 PMCID: PMC1287567 DOI: 10.1128/jvi.79.23.14748-14755.2005] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A quantitative description of the binding interactions between human immunodeficiency virus (HIV) type 1 envelope glycoproteins and their host cell surface receptors remains incomplete. Here, we introduce a single-molecule analysis that directly probes the binding interactions between an individual viral subunit gp120 and a single receptor CD4 and/or chemokine coreceptor CCR5 in living cells. This analysis differentiates single-molecule binding from multimolecule avidity and shows that, while the presence of CD4 is required for gp120 binding to CCR5, the force required to rupture a single gp120-coreceptor bond is significantly higher and its lifetime is much longer than those of a single gp120-receptor bond. The lifetimes of these bonds are themselves shorter than those of the P-selectin/PSGL-1 bond involved in leukocyte attachment to the endothelium bonds during an inflammation response. These results suggest an amended model of HIV entry in which, immediately after the association of gp120 to its receptor, gp120 seeks its coreceptor to rapidly form a new bond. This "bond transfer" occurs only if CCR5 is in close proximity to CD4 and CD4 is still attached to gp120. The analysis presented here may serve as a general framework to study mechanisms of receptor-mediated interactions between viral envelope proteins and host cell receptors at the single-molecule level in living cells.
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Affiliation(s)
- Melissa I Chang
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
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19
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Sloane AJ, Raso V, Dimitrov DS, Xiao X, Deo S, Muljadi N, Restuccia D, Turville S, Kearney C, Broder CC, Zoellner H, Cunningham AL, Bendall L, Lynch GW. Marked structural and functional heterogeneity in CXCR4: separation of HIV-1 and SDF-1alpha responses. Immunol Cell Biol 2005; 83:129-43. [PMID: 15748209 DOI: 10.1111/j.1440-1711.2004.01304.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
CXCR4, the chemotactic cell receptor for SDF-1alpha, is essential for immune trafficking and HIV infection. CXCR4 is remarkably heterogeneous and the purpose of this study was to better identify the isoforms expressed by cells and compare their structure and function. We found that cells express either a predominant isoform or multiple isoforms. These were best resolved on SDS-PAGE using sucrose-gradient-fractionated, triton-insoluble, membrane extracts. We hypothesized that glycosyl modification may underpin some of this heterogeneity and that cell isoform(s) differences may underscore CXCR4's multiple cell functions. A comparison of wild-type (WT) and dual N-linked glycosylation site, N11A/N176A, mutant CXCR4 expressed in 3T3 and HEK-293 cells served to implicate variabilities in glycosylation and oligomerization in almost half of the isoforms. Immunoprecipitation of CXCR4 revealed monomer and dimer non-glycosylated forms of 34 kDa and 68 kDa from the N11A/N176A mutant, compared with glycosylated 40 kDa and 47 kDa and 73 kDa and 80 kDa forms from WT. The functional specificity of isoform action was also implicated because, despite CEMT4 cells expressing high levels of CXCR4 and 11 different isoforms, a single 83 kDa form was found to bind gp120 for HIV-1 IIIB infection. Furthermore, comparative studies found that in contrast to SDF-1alpha-responsive Nalm-6 cells that expressed similar levels of a single isoform, CEMT4 cells did not show a Ca(++) flux or a chemotactic response to SDF-1alpha. Thus, CXCR4 can differ both structurally and functionally between cells, with HIV-1 infection and chemotaxis apparently mediated by different isoforms. This separation of structure and function has implications for understanding HIV-1 entry and SDF-1alpha responses and may indicate therapeutic possibilities.
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Affiliation(s)
- Andrew J Sloane
- HIV-Protein Interactions Laboratory, Centre for Virus Research, Westmead, NSW, Australia
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20
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Wilson MC, Meredith D, Fox JEM, Manoharan C, Davies AJ, Halestrap AP. Basigin (CD147) is the target for organomercurial inhibition of monocarboxylate transporter isoforms 1 and 4: the ancillary protein for the insensitive MCT2 is EMBIGIN (gp70). J Biol Chem 2005; 280:27213-21. [PMID: 15917240 DOI: 10.1074/jbc.m411950200] [Citation(s) in RCA: 218] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Translocation of monocarboxylate transporters MCT1 and MCT4 to the plasma membrane requires CD147 (basigin) with which they remain tightly associated. However, the importance of CD147 for MCT activity is unclear. MCT1 and MCT4 are both inhibited by the cell-impermeant organomercurial reagent p-chloromercuribenzene sulfonate (pCMBS). Here we demonstrate by site-directed mutagenesis that removal of all accessible cysteine residues on MCT4 does not prevent this inhibition. pCMBS treatment of cells abolished co-immunoprecipitation of MCT1 and MCT4 with CD147 and enhanced labeling of CD147 with a biotinylated-thiol reagent. This suggested that CD147 might be the target of pCMBS, and further evidence for this was obtained by treatment of cells with the bifunctional organomercurial reagent fluorescein dimercury acetate that caused oligomerization of CD147. Site-directed mutagenesis of CD147 implicated the disulfide bridge in the Ig-like C2 domain of CD147 as the target of pCMBS attack. MCT2, which is pCMBS-insensitive, was found to co-immunoprecipitate with gp70 rather than CD147. The interaction between gp70 and MCT2 was confirmed using fluorescence resonance energy transfer between the cyan fluorescent protein- and yellow fluorescent protein-tagged MCT2 and gp70. pCMBS strongly inhibited lactate transport into rabbit erythrocytes, where MCT1 interacts with CD147, but not into rat erythrocytes where it interacts with gp70. These data imply that inhibition of MCT1 and MCT4 activity by pCMBS is mediated through its binding to CD147, whereas MCT2, which associates with gp70, is insensitive to pCMBS. We conclude that ancillary proteins are required to maintain the catalytic activity of MCTs as well as for their translocation to the plasma membrane.
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Affiliation(s)
- Marieangela C Wilson
- Department of Biochemistry, University of Bristol, School of Medical Sciences, University Walk, Bristol BS8 1TD, United Kingdom
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21
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Abstract
It has recently been shown that disulfide bond Cys130-Cys159 in domain 2 of monomeric CD4 is involved in the formation of CD4 disulfide-bonded dimers on cell surfaces and that it can influence the permissiveness of cells to HIV infection. Because this disulfide bond is buried in the monomer, a large conformational change must take place in order to allow for such disulfide exchange. Using standard optimization techniques, whose efficiency was first checked in the well-documented CD2 case, we have shown that 3D domain swapping is a likely candidate for the conformational change, the hinge loop, or linker, being loop E-F. Indeed, as a consequence of domain swapping, because Cys130 and Cys159 belong to beta-strands C and F, respectively, two disulfide bonds become established between Cys130 in one monomer and Cys159 in the other one. Such a disulfide exchange has already been observed when the nuclear magnetic resonance (NMR) structure of the prion protein was compared to the crystallographic, dimeric one. In both cases, domain swapping implies disulfide exchange because the linker is located in the sequence between two disulfide-bonded cysteines. As in the CD2 case, the proposed configuration of the CD4 dimer is found as a pair of neighboring monomers in the crystallographic unit cell. Moreover, because in this configuration the epitope of monoclonal antibody MT151, which does not compete with Gp120 for CD4 binding, is in the cleft between the pair of CD4 monomers, it is suggested that MT151 achieves its HIV-blocking activity by interfering with the formation of CD4 domain-swapped dimers on cell surface.
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Affiliation(s)
- Yves-Henri Sanejouand
- Laboratoire de Physique, Ecole Normale Supérieure, 46 allées d'Italie, 69364 Lyon Cédex 07, France.
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22
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Li QJ, Dinner AR, Qi S, Irvine DJ, Huppa JB, Davis MM, Chakraborty AK. CD4 enhances T cell sensitivity to antigen by coordinating Lck accumulation at the immunological synapse. Nat Immunol 2004; 5:791-9. [PMID: 15247914 DOI: 10.1038/ni1095] [Citation(s) in RCA: 181] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2004] [Accepted: 06/18/2004] [Indexed: 11/09/2022]
Abstract
How T cells respond with extraordinary sensitivity to minute amounts of agonist peptide and major histocompatibility complex (pMHC) molecules on the surface of antigen-presenting cells bearing large numbers of endogenous pMHC molecules is not understood. Here we present evidence that CD4 affects the responsiveness of T helper cells by controlling spatial localization of the tyrosine kinase Lck in the synapse. This finding, as well as further in silico and in vitro experiments, led us to develop a molecular model in which endogenous and agonist pMHC molecules act cooperatively to amplify T cell receptor signaling. At the same time, activation due to endogenous pMHC molecules alone is inhibited. A key feature is that the binding of agonist pMHC molecules to the T cell receptor results in CD4-mediated spatial localization of Lck, which in turn enables endogenous pMHC molecules to trigger many T cell receptors. We also discuss broader implications for T cell biology, including thymic selection, diversity of the repertoire of self pMHC molecules and serial triggering.
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Affiliation(s)
- Qi-Jing Li
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California 94305, USA
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23
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El Fakhry Y, Bouillon M, Léveillé C, Brunet A, Khalil H, Thibodeau J, Mourad W. Delineation of the HLA-DR Region and the Residues Involved in the Association with the Cytoskeleton. J Biol Chem 2004; 279:18472-80. [PMID: 14976194 DOI: 10.1074/jbc.m401159200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Whereas the association of major histocompatibility complex (MHC) class II molecules with the cytoskeleton and their recruitment into lipid rafts play a critical role during cognate T/antigen-presenting cell interactions, MHC class II-induced signals, regions, and residues involved in their association and recruitment have not yet been fully deciphered. In this study, we show that oligomerization of HLA-DR molecules induces their association with the cytoskeleton and their recruitment into lipid rafts. The association of oligomerized HLA-DR molecules with the cytoskeleton and their recruitment into lipid rafts occur independently. Furthermore, the association with the cytoskeleton is HLA-DR-specific, since oligomerization of HLA-DP triggers its recruitment only into lipid rafts. HLA-DR molecules devoid of both alpha and beta cytoplasmic tails did not associate with the cytoskeleton, but their recruitment into lipid rafts was unimpeded. Deletion of either the alpha or beta cytoplasmic tail did not affect the association of HLA-DR with the cytoskeleton and/or recruitment into lipid rafts. HLA-DR molecules that were devoid of the alpha cytoplasmic chain and that had their beta cytoplasmic chain replaced with the HLA-DP beta chain or with a beta chain in which the residues at positions Gly(226)-His(227)-Ser(228) were substituted by alanine no longer associated with the cytoskeleton. They were, however, still recruited into lipid rafts. Together, these results support the involvement of different regions of the cytoplasmic tails in the association and the recruitment of HLA-DR into different compartments. The differential behavior of HLA-DP and -DR with respect to their association with the cytoskeleton may explain the previously described difference in their transduced signals.
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Affiliation(s)
- Youssef El Fakhry
- Centre de Recherche en Rhumatologie et Immunologie, Centre Hospitalier de l'Université Laval (CHUL), Département de médecine, Université Laval, Quebec City, Quebec, G1V 4G2 Canada
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24
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Bernhard OK, Cunningham AL, Sheil MM. Analysis of proteins copurifying with the CD4/lck complex using one-dimensional polyacrylamide gel electrophoresis and mass spectrometry: comparison with affinity-tag based protein detection and evaluation of different solubilization methods. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2004; 15:558-567. [PMID: 15047060 DOI: 10.1016/j.jasms.2003.12.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2003] [Revised: 12/15/2003] [Accepted: 12/16/2003] [Indexed: 05/24/2023]
Abstract
Mass spectrometry-based identification of the components of affinity purified protein complexes after polyacrylamide gel electrophoresis (PAGE) and in-gel digest has become very popular for the detection of novel protein interactions. As an alternative, the entire protein complex can be subjected to proteolytic cleavage followed by chromatographic separation of the peptides. Based on our earlier report of a method using affinity tag-mediated purification of cysteine-containing peptides to analyse proteins present in an affinity purification of the CD4/lck receptor complex, we here evaluated the use of one-dimensional polyacrylamide gel electrophoresis for analysis of the same receptor complex purification. Using electrospray and tandem mass spectrometry analyses of tryptic peptides from in-gel digested proteins we identified the components of the CD4 receptor complex along with 23 other proteins that were all likely to be non-specifically binding proteins and mainly different from the proteins detected in our previous study. We compare the alternative strategy with the affinity tag-based method that we described earlier and show that the PAGE-based method enables more proteins to be identified. We also evaluated the use of a more stringent lysis buffer for the CD4 purification to minimise non-specific binding and identified 52 proteins along with CD4 in three independent experiments suggesting that the choice of lysis buffer had no significant effect on the extent of non-specific binding. Non-specific binding was inconsistent and involved various types of proteins underlining the importance of reproducibility and control experiments in proteomic studies.
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Affiliation(s)
- Oliver K Bernhard
- Center for Virus Research, Westmead Millennium Institute, National Center for HIV Virology Research, Westmead Hospital and the University of Sydney, Westmead, New South Wales, Australia
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25
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Bernhard OK, Sheil MM, Cunningham AL. Lateral Membrane Protein Associations of CD4 in Lymphoid Cells Detected by Cross-Linking and Mass Spectrometry. Biochemistry 2003; 43:256-64. [PMID: 14705953 DOI: 10.1021/bi034847u] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Interactions of membrane proteins are important in various aspects of cell function. However, weak membrane protein-protein interactions are difficult to study using techniques such as co-immunoprecipitations. CD4 is a cell surface protein involved in T cell activation and the binding of the human immunodeficiency virus to HIV target cells. Here we report the use of cross-linking followed by affinity purification of CD4 in combination with mass spectrometry for identification of proteins that are in the proximity of CD4. Besides the components of the CD4 receptor complex, CD4 and lck, we have identified by tandem mass spectrometry 17 tryptic peptides from transferrin receptor CD71, three peptides from protein phosphatase CD45, and one peptide from 4F2 lymphocyte activation antigen CD98. The efficiency of the cross-linking did not correlate with the level of cell surface expression of the detected molecules, excluding a possible bias of the cross-linking toward the most abundant cell surface molecules. Whereas the association of CD4 with CD45 has been reported, the associations with CD71 and CD98 have not been previously described. We used small-scale immunoprecipitation after cross-linking in combination with fluorescence resonance energy transfer (FRET) measurements to investigate the association between CD4 and CD71. Our data show that CD71 self-associates on the cell surface, that a small fraction of CD4 can be detected by copurifying it with CD71 after cross-linking, and that the level of association between CD4 and CD71 significantly increases after phorbol 12-myristate 13-acetate-induced endocytosis of CD4. This suggests that a small fraction of CD4 associates with clusters of CD71. As both molecules undergo endocytic recycling, the association and cross-linking result from their clustering in the same pit and/or vesicle. The CD4-CD98 association probably results from nonspecific cross-linking.
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MESH Headings
- Antigens, CD/biosynthesis
- Antigens, CD/isolation & purification
- Antigens, CD/metabolism
- Antigens, Differentiation, B-Lymphocyte/biosynthesis
- Antigens, Differentiation, B-Lymphocyte/isolation & purification
- Antigens, Differentiation, B-Lymphocyte/metabolism
- Blotting, Western
- CD4 Antigens/biosynthesis
- CD4 Antigens/chemistry
- CD4 Antigens/isolation & purification
- CD4 Antigens/metabolism
- Cell Line, Transformed
- Cell Membrane/chemistry
- Cell Membrane/metabolism
- Chromatography, Affinity
- Cross-Linking Reagents/chemistry
- Endocytosis/drug effects
- Fluorescence Resonance Energy Transfer
- Fusion Regulatory Protein-1/biosynthesis
- Humans
- Leukocyte Common Antigens/biosynthesis
- Lymphocytes/chemistry
- Lymphocytes/drug effects
- Lymphocytes/metabolism
- Membrane Proteins/biosynthesis
- Membrane Proteins/chemistry
- Membrane Proteins/isolation & purification
- Membrane Proteins/metabolism
- Precipitin Tests
- Receptors, Transferrin
- Spectrometry, Mass, Electrospray Ionization/methods
- Succinimides/chemistry
- Tetradecanoylphorbol Acetate/pharmacology
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Affiliation(s)
- Oliver K Bernhard
- Centre for Virus Research, Westmead Millennium Institute, National Centre for HIV Virology Research, Westmead Hospital and The University of Sydney, Darcy Road, Westmead, NSW 2145, Australia
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26
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Lynch GW, Slaytor EK, Elliott FD, Saurajen A, Turville SG, Sloane AJ, Cameron PU, Cunningham AL, Halliday GM. CD4 is expressed by epidermal Langerhans' cells predominantly as covalent dimers. Exp Dermatol 2003; 12:700-11. [PMID: 14705812 DOI: 10.1034/j.1600-0625.2003.00078.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Langerhans' cells (LC) of skin are CD4 expressing, dendritic, antigen-presenting cells, that are essential for activation of primary immune responses and are productively infected by HIV. We have shown previously that lymphocytes and monocytes express CD4 both as monomers and covalently linked homodimers. In those cells the 55-kDa monomer structure predominates. LC in un-fractionated human epidermal cell (EC) suspension also expresses both forms of CD4, but in EC the dimer form is predominant. Because isolation of LC into single cell suspension by trypsin, as is routinely used for LC isolation, degrades CD4, a systematic study for an alternate procedure for LC isolation was performed. Thus it was found that collagenase blend F treatment can efficiently release LC into suspension, under conditions of only minimal degradation of control soluble recombinant CD4 or CEM-T4 or THP-1 cell CD4, or importantly of LC surface CD4. SDS-PAGE immunoblotting of purified LC extracted from EC by collagenase confirmed CD4 structure as predominantly 110-kDa dimers, with only minimal 55-kDa monomers. The suitability of LC prepared thus for functional studies was demonstrated with binding of functional ligand HIV gp120. It remains to be determined, however, why tissue embedded LC express mainly CD4 dimers, but single-celled blood lymphocytes and monocytes mainly monomers.
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Affiliation(s)
- G W Lynch
- Centre for Virus Research, Westmead Millennium Institute, University of Sydney, Westmead Hospital, Sydney, Australia.
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27
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Abstract
The chemokine receptor CCR5 is constitutively associated with the T cell co-receptor CD4 in plasma cell membranes. The CD4-CCR5 complex exhibits distinct binding properties for macrophage inflammatory protein 1beta (MIP-1beta) and enhanced G-protein signaling as compared with those of CCR5 alone. Here we report that recombinant soluble CD4, when refolded into its dimeric form, allosterically modulates CCR5 and decreases the affinity for its natural ligand MIP-1beta. Monomeric soluble CD4 had little inhibitory effect on CCR5. In contrast, the two-domain amino-terminal fragment of soluble CD4 was able to completely inhibit the interaction of CCR5 with MIP-1beta. Thus, we suggest that various conformational states of CD4 exist, which differ markedly with regard to inhibiting the interaction of CCR5 with its ligand MIP-1beta. R5-tropic HIV-1 glycoprotein 120, but not interleukin-16, the natural agonist, or X4-tropic glycoprotein 120, inhibited MIP-1beta binding to CCR5 in the presence of monomeric and dimeric soluble CD4.
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Affiliation(s)
- Xiaohong Wang
- Veterans Affairs New York Harbor Healthcare System, New York Campus, New York, USA
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28
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Zhou W, König R. T cell receptor-independent CD4 signalling: CD4-MHC class II interactions regulate intracellular calcium and cyclic AMP. Cell Signal 2003; 15:751-62. [PMID: 12781868 DOI: 10.1016/s0898-6568(03)00037-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
CD4 is a coreceptor on T helper (Th) cells that interacts with MHC class II molecules (MHCII). The mechanisms mediating the effects of CD4 on responses by T helper cells to stimulation of the antigen-specific T cell receptor (TCR) are still poorly understood. Here, we demonstrate T cell costimulation via CD4 signalling independent of T cell receptor-mediated signals. Incubation of T helper cells with peptide mimetics of the CD4-binding region on the MHC class II beta2 domain caused intracellular calcium mobilization in the absence of antigen or other T cell receptor stimuli. Engagement of CD4 by peptide mimetics or wild-type MHC class II, but not by mutant MHC class II molecules incapable of engaging CD4, inhibited the T cell receptor-mediated increase in cyclic AMP (cAMP) concentrations in T helper cells. CD4-mediated signals activated cyclic AMP phosphodiesterases (PDEs) and inhibited adenylyl cyclase. Full activation and clonal expansion of antigen-stimulated T helper cells required the CD4-mediated regulation of cyclic AMP. Our results suggest a costimulatory mechanism of CD4 function that acts on the second messengers, calcium and cyclic AMP.
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Affiliation(s)
- Wenhong Zhou
- Department of Microbiology and Immunology, The University of Texas Medical Branch, Galveston, TX 77555-1070, USA
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29
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Abstract
Recent genomic analysis has shown that proteins with immunoglobulin superfamily (IgSF) domains are extremely abundant and their number has increased markedly in evolution correlating with the development of the adaptive immune system. The IgSF domain is particularly good at being recognised and is involved in many different kinds of interactions. Thus, analysis of the properties of these domains can act as a paradigm for thinking about the roles of newly identified gene products. This review summarises the identification, function and properties of IgSF domains including, their size, variety of interactions, their strength of binding, role of glycosylation and organisation with other proteins.
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Affiliation(s)
- A Neil Barclay
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
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Nakamura K, Yube K, Miyatake A, Cambier JC, Hirashima M. Involvement of CD4 D3-D4 membrane proximal extracellular domain for the inhibitory effect of oxidative stress on activation-induced CD4 down-regulation and its possible role for T cell activation. Mol Immunol 2003; 39:909-21. [PMID: 12695117 DOI: 10.1016/s0161-5890(03)00030-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
During antigen presentation, CD4 functions to stabilize T cell receptor (TCR)-class II MHC interactions and coordinate Ag-induced T cell activation signals. These activation signals cause CD4 down-regulation, presumably acting to optimize T cell activation. We previously reported that oxidative stress interferes with activation-induced CD4 down-regulation in T cells. In this study, we have further investigated inhibition of CD4 down-regulation by oxidative stress and its role for T cell activation. A construct comprised of the mouse FcgammaRIIB extracellular domain and the transmembrane/cytoplasmic domains of human CD4 (FcgammaR/CD4) was expressed in a human T cell line. Oxidant actually potentiated down-regulation of the FcgammaR/CD4 chimera and induced Lck dissociation from both CD4 and FcgammaR/CD4, which is a crucial intracellular process for activation-induced CD4 down-regulation, suggesting a critical role of CD4 ectodomain in the inhibition of CD4 down-regulation by oxidative stress. Furthermore, insertion of CD4 D3-D4 membrane proximal extracellular region between FcgammaR extracellular domain and CD4 transmembrane/cytoplasmic domains in FcgammaR/CD4 chimera made this molecule behave like native CD4 molecule under oxidative stress condition. These data imply that the inhibitory effect of oxidative stress on CD4 down-regulation is executed via D3-D4 domain of CD4 ectodomain. As to its role for T cell activation, CD4 coaggregation with CD3 under the oxidative conditions enhanced activation signal induced by CD3 aggregation. Our results demonstrate that Ag-induced T cell activation which is normally concomitant with CD4 down-regulation may be disturbed through the aberrant regulation of CD4 expression by oxidative stress.
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Affiliation(s)
- K Nakamura
- Department of Immunology and Immunopathology, Kagawa Medical University, 1750-1 Ikenobe, Miki, Kita-gun, 761-0793, Kagawa, Japan.
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31
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Ellmark P, Furebring C, Borrebaeck CAK. Pre-assembly of the extracellular domains of CD40 is not necessary for rescue of mouse B cells from anti-immunoglobulin M-induced apoptosis. Immunology 2003; 108:452-7. [PMID: 12667206 PMCID: PMC1782917 DOI: 10.1046/j.1365-2567.2003.01622.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
CD40 is a tumour necrosis factor receptor (TNFR) family member of central importance for the adaptive immune system. To elucidate the functional role of the different extracellular domains of CD40, we have created a set of truncated CD40 molecules where domains, or parts of domains, have been removed. These CD40 proteins, which contain a peptide tag in the N-terminal end, have been expressed in a murine B-cell line, WEHI 231. It was found that ligation of these engineered CD40 proteins via the peptide tag, was sufficient to rescue as well as to promote proliferation of apoptotic WEHI 231 cells, even when all the extracellular domains of CD40 were absent. Our results suggest that pre association of CD40 in the cell membrane plays no critical role for the CD40 signalling pathway. Furthermore, our data imply that conformational changes initiated in the extracellular domains of CD40 are not essential for signal transduction.
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Affiliation(s)
- Peter Ellmark
- Department of Immunotechnology, Lund University Lund, Sweden
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32
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Kalus I, Schnegelsberg B, Seidah NG, Kleene R, Schachner M. The proprotein convertase PC5A and a metalloprotease are involved in the proteolytic processing of the neural adhesion molecule L1. J Biol Chem 2003; 278:10381-8. [PMID: 12529374 DOI: 10.1074/jbc.m208351200] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The transmembrane and multidomain neural adhesion molecule L1 plays important functional roles in the developing and adult nervous system. L1 is proteolytically processed at two distinct sites within the extracellular domain, leading to the generation of different fragments. In this report, we present evidence that the proprotein convertase PC5A is the protease that cleaves L1 in the third fibronectin type III domain, whereas the proprotein convertases furin, PC1, PC2, PACE4, and PC7 are not effective in cleaving L1. Analysis of mutations revealed Arg(845) to be the site of cleavage generating the N-terminal 140-kDa fragment. This fragment was present in the hippocampus, which expresses PC5A, but was not detectable in the cerebellum, which does not express PC5A. The 140-kDa L1 fragment was found to be tightly associated with the full-length 200-kDa L1 molecule. The complex dissociated from the membrane upon cleavage by a protease acting at a more membrane-proximal site of full-length L1. This proteolytic cleavage was inhibited by the metalloprotease inhibitor GM 6001 and enhanced by a calmodulin inhibitor. L1-dependent neurite outgrowth of cerebellar neurons was inhibited by GM 6001, suggesting that proteolytic processing of L1 by a metalloprotease is involved in neurite outgrowth.
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Affiliation(s)
- Ina Kalus
- Zentrum für Molekulare Neurobiologie, University of Hamburg, Martinistrasse 52, Germany
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33
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Abstract
Proteins that work outside cells nearly always contain disulfide bonds. The prevailing view is that these bonds have been added during evolution to enhance protein stability. Recent evidence suggests that disulfide bonds can also control protein function. Certain secreted proteins contain one or more disulfide bonds that can control function by breaking and reforming in a controlled way. This review focuses on disulfide exchange events on the cell surface, with a particular reference to two proteins involved in HIV-1 infection. The primary HIV-1 receptor on immune cells, CD4, and the viral envelope glycoprotein, gp120, play a central role in HIV-1 entry. Redox change in a disulfide bond or bonds in one or both of these proteins appears to be important for HIV-1 entry.
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Affiliation(s)
- Lisa J Matthias
- Centre for Vascular Research, University of New South Wales, Sydney, NSW 2052, Australia
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34
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Affiliation(s)
- Lisa J Matthias
- Centre for Thrombosis and Vascular Research, School of Medical Sciences, University of New South Wales, Australia
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35
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Moldovan MC, Yachou A, Lévesque K, Wu H, Hendrickson WA, Cohen EA, Sékaly RP. CD4 dimers constitute the functional component required for T cell activation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:6261-8. [PMID: 12444132 DOI: 10.4049/jimmunol.169.11.6261] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The CD4 molecule plays a key role in the development and activation of helper T cells. Dimerization and oligomerization is often a necessary step in the function of several cell surface receptors. Herein, we provide direct biochemical evidence confirming the presence of CD4 as dimers in transfected cells from hemopoetic and fibroblastic origin as well as in primary T cells. Such dimers are also observed with murine CD4 confirming selective pressure during evolution to maintain such a structure. Using a series of point mutations, we have precisely mapped the dimerization site at residues K318 and Q344 within the fourth extracellular domain of CD4. These residues are highly conserved and their mutation results in interference with dimer formation. More importantly, we demonstrate that dimer formation is essential for the coligand and coreceptor functions of CD4 in T cell activation. These data strongly suggest that CD4 dimerization is necessary for helper T cell function.
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36
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Matthias LJ, Yam PTW, Jiang XM, Vandegraaff N, Li P, Poumbourios P, Donoghue N, Hogg PJ. Disulfide exchange in domain 2 of CD4 is required for entry of HIV-1. Nat Immunol 2002; 3:727-32. [PMID: 12089508 DOI: 10.1038/ni815] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
CD4, a member of the immunoglobulin superfamily of receptors that mediates cell-cell interactions in the immune system, is the primary receptor for HIV-1. The extracellular portion of CD4 is a concatenation of four immunoglobulin-like domains, D1 to D4. The D1, D2 and D4 domains each contain a disulfide bond. We show here that the D2 disulfide bond is redox-active. The redox state of the thiols (disulfide versus dithiol) appeared to be regulated by thioredoxin, which is secreted by CD4(+) T cells. Locking the CD4 and the thioredoxin active-site dithiols in the reduced state with a hydrophilic trivalent arsenical blocked entry of HIV-1 into susceptible cells. These findings indicate that redox changes in CD4 D2 are important for HIV-1 entry and represent a new target for HIV-1 entry inhibitors.
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Affiliation(s)
- Lisa J Matthias
- Centre for Thrombosis and Vascular Research, School of Medical Sciences, University of New South Wales and Department of Haematology, Prince of Wales Hospital, Sydney, NSW 2052, Australia
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37
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Shigehara T, Mitsuhashi H, Ota F, Kuroiwa T, Kaneko Y, Ueki K, Tsukada Y, Maezawa A, Nojima Y. Sulfite induces adherence of polymorphonuclear neutrophils to immobilized fibrinogen through activation of Mac-1 beta2-integrin (CD11b/CD18). Life Sci 2002; 70:2225-32. [PMID: 12005182 DOI: 10.1016/s0024-3205(01)01530-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Sulfite is a major air pollutant which can cause respiratory tract inflammation characterized by an influx of polymorphonuclear neutrophils (PMN). We have previously shown that human PMN can produce sulfite either spontaneously or in response to stimulation with lipopolysaccharide. We now demonstrate that sulfite activates PMN to adhere to immobilized fibrinogen via the beta2-integrin Mac-1 (CD11b/CD18). Mac-1 expression is not altered by treatment with this agent. Although unaffected by pertussis toxin, sulfite-triggered PMN adhesion was abrogated by pretreating cells with the membrane-impermeant sulfhydryl reagent 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), a modifier of thiol groups on the cell surface. These results suggest that sulfite-induced PMN adhesion is dependent on a modification of thiols at the cell surface. Given its potent antioxidant and antimicrobial activities, sulfite may act as an endogenous mediator in host defense and/or inflammation.
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Affiliation(s)
- Tetsuya Shigehara
- Third Department of Internal Medicine, Gunma University School of Medicine, Maebashi, Japan
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38
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Abstract
Genetic experiments indicate similarity between binding sites on MHC class I (MHCI) for CD8 and on MHCII for CD4, but the crystal structures of CD8/MHCI and CD4/MHCII complexes suggest critical differences between the interfaces in the two complexes. Biophysical analyses using ectodomains of co-receptors and MHC molecules demonstrate extremely fast kinetics and low-affinity interactions. Experiments with soluble multimeric MHC ligands suggest that CD4 and CD8 may differ in the mechanisms by which they promote the formation of ternary TCR/MHC/co-receptor complexes. Co-receptor-influenced duration of TCR signaling controls thymocyte selection. In naïve T cells, CD4/MHCII interactions may promote T-cell survival. Temporal and spatial analysis of TCR and CD4 co-clustering in the immunological synapse suggests that CD4 recruitment is regulated by the half-life of the initial TCR/MHCII complex. Diverse experimental systems have yielded conflicting data that have helped to formulate revised mechanistic models of co-receptor function.
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Affiliation(s)
- Rolf König
- Department of Microbiology and Immunology and the Sealy Center for Molecular Science, The University of Texas Medical Branch, Galveston, TX 77555-1070, USA
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39
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Fishman-Lobell J, Tsui P, Reddy M, DiPrinzio R, Eichman C, Sweet RW, Truneh A. CD4 mAb induced apoptosis of peripheral T cells: multiparameter subpopulation analysis by flow cytometry using Attractors. J Immunol Methods 2001; 257:71-82. [PMID: 11687240 DOI: 10.1016/s0022-1759(01)00447-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Studies describing the induction of apoptosis for CD4 mAbs do not delineate between epitope-dependent and Fc-driven epitope cross-linking induced cell death. Keliximab and clenoliximab are two CD4 mAbs that differ only in their heavy chain isotypes, being an IgG1 and a modified IgG4, respectively. These antibodies suppress CD4 T cell responses in vitro and in vivo and have been in human clinical trials for the treatment of RA and asthma. Here we compared the apoptotic activity of these mAbs to differentiate between the contributions of epitope-dependent vs. Fc-driven epitope cross-linking induced cell death in vitro as a link to differential CD4 cell depletion in vivo. We developed a simple flow cytometry procedure that measures apoptosis within intact and compromised subpopulations of PBMCs within a few hours of culture. Attractors software was used to quantitate the percentage of apoptotic CD4 T cells, which generate reactive oxygen species (ROS), express external phosphatidyl serine (PS) and cleaved fluorescein diacetate (FDA), within the intact and compromised lymphocyte populations. Treatment of freshly isolated PBMCs with keliximab resulted in the appearance of characteristic apoptotic condensed CD4 T cells that contained reactive oxygen species, were annexin V positive and had intact esterase activity. Apoptosis was evident within 3 h and continued throughout the 72-h culture period. In contrast, clenoliximab alone did not induce apoptosis. The use of multiparameter flow cytometry and Attractors to analyze subpopulations based on scatter properties and biochemical processes during apoptosis provides a sensitive assay in which to quantitate and characterize the induction of cell death. Depletion of CD4 T cells in vivo by keliximab may reflect, in part, antibody-mediated apoptosis of these cells that is dependent on Fcgamma receptors.
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Affiliation(s)
- J Fishman-Lobell
- Department of Oncology Research, SmithKline Beecham Pharmaceuticals, UW2101, 709 Swedeland Road, King of Prussia, PA 19406 USA.
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40
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Wang Q, Malherbe L, Zhang D, Zingler K, Glaichenhaus N, Killeen N. CD4 promotes breadth in the TCR repertoire. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:4311-20. [PMID: 11591754 DOI: 10.4049/jimmunol.167.8.4311] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A diverse population of MHC class II-restricted CD4 lineage T cells develops in mice that lack expression of the CD4 molecule. In this study, we show that the TCR repertoire selected in the absence of CD4 is distinct, but still overlapping in its properties with that selected in the presence of CD4. Immunization of mice lacking CD4 caused the clonal expansion of T cells that showed less breadth in the range of Ag-binding properties exhibited by their TCRs. Specifically, the CD4-deficient Ag-specific TCR repertoire was depleted of TCRs that demonstrated low-affinity binding to their ligands. The data thus suggest a key role for CD4 in broadening the TCR repertoire by potentiating productive TCR signaling and clonal expansion in response to the engagement of low-affinity antigenic ligands.
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Affiliation(s)
- Q Wang
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94143, USA
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41
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Van Broekhoven CL, Altin JG. A novel system for convenient detection of low-affinity receptor-ligand interactions: chelator-lipid liposomes engrafted with recombinant CD4 bind to cells expressing MHC class II. Immunol Cell Biol 2001; 79:274-84. [PMID: 11380681 DOI: 10.1046/j.1440-1711.2001.01010.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The interactions of cell surface receptors with their ligands, crucial for initiating many immunological responses, are often stabilized by receptor dimerization/oligomerization, and by multimeric interactions between receptors on one cell with their ligands or cognate receptors on the apposing cell. Current techniques for studying receptor-ligand interactions, however, do not always allow receptors to move laterally to enable dimerization/ oligomerization, or to interact multimerically with ligands on cell surfaces. For these reasons detection of low- affinity receptor-ligand interactions has been difficult. Utilizing a novel chelator-lipid, nitrilotriacetic acid di-tetradecylamine (NTA-DTDA), we have developed a convenient liposome system for directly detecting low-affinity receptor-ligand interactions. Our studies using recombinant soluble forms of murine CD40 and B7.1, and murine and human CD4, each possessing a hexhistidine tag, showed that these proteins can be anchored or 'engrafted' directly onto fluorescently labelled liposomes via a metal-chelating linkage with NTA-DTDA, permitting them to undergo dimerization/oligomerization and multimeric binding with ligands on cells. Fluorescence- activated cell sorter (FACS) analyses demonstrated that while there is little if any binding of soluble forms of murine CD40 and B7.1, and murine and human CD4 to cells, engrafted liposomes bind specifically to cells expressing the appropriate cognate receptor, often giving a fluorescence 4-6-fold above control cells. Such liposomes could detect directly the low-affinity interaction of murine CD40 and B7.1 with CD154- and CD28-expressing cells, respectively, and the interaction of CD4 with MHC Class II, which has hitherto defied direct detection except through mutational analysis and mAb blocking studies.
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Affiliation(s)
- C L Van Broekhoven
- School of Biochemistry and Molecular Biology, Faculty of Science, Australian National University, Canberra, Australian Capital Territory, Australia
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42
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Donoghue N, Yam PT, Jiang XM, Hogg PJ. Presence of closely spaced protein thiols on the surface of mammalian cells. Protein Sci 2000; 9:2436-45. [PMID: 11206065 PMCID: PMC2144521 DOI: 10.1110/ps.9.12.2436] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
It has been proposed that certain cell-surface proteins undergo redox reactions, that is, transfer of hydrogens and electrons between closely spaced cysteine thiols that can lead to reduction, formation, or interchange of disulfide bonds. This concept was tested using a membrane-impermeable trivalent arsenical to identify closely spaced thiols in cell-surface proteins. We attached the trivalent arsenical, phenylarsenoxide, to the thiol of reduced glutathione to produce 4-(N-(S-glutathionylacetyl)amino)phenylarsenoxide (GSAO). GSAO bound tightly to synthetic, peptide, and protein dithiols like thioredoxin, but not to monothiols. To identify cell-surface proteins that contain closely spaced thiols, we attached a biotin moiety through a spacer arm to the primary amino group of the gamma-glutamyl residue of GSAO (GSAO-B). Incorporation of GSAO-B into proteins was assessed by measuring the biotin using streptavidin-peroxidase. Up to 12 distinct proteins were labeled with GSAO-B on the surface of endothelial and fibrosarcoma cells. The pattern of labeled proteins differed between the different cell types. Protein disulfide isomerase was one of the proteins on the endothelial and fibrosarcoma cell surface that incorporated GSAO-B. These findings demonstrate that the cell-surface environment can support the existence of closely spaced protein thiols and suggest that at least some of these thiols are redox active.
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Affiliation(s)
- N Donoghue
- Centre for Thrombosis and Vascular Research, School of Pathology, University of New South Wales, Sydney, Australia
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43
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Cunningham AL, Li S, Juarez J, Lynch G, Alali M, Naif H. The level of HIV infection of macrophages is determined by interaction of viral and host cell genotypes. J Leukoc Biol 2000. [DOI: 10.1189/jlb.68.3.311] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- A. L. Cunningham
- Centre for Virus Research, The Westmead Millennium Institute, University of Sydney, and The Australian National Centre for HIV Research, Sydney, Australia
| | - S Li
- Centre for Virus Research, The Westmead Millennium Institute, University of Sydney, and The Australian National Centre for HIV Research, Sydney, Australia
| | - J Juarez
- Centre for Virus Research, The Westmead Millennium Institute, University of Sydney, and The Australian National Centre for HIV Research, Sydney, Australia
| | - G Lynch
- Centre for Virus Research, The Westmead Millennium Institute, University of Sydney, and The Australian National Centre for HIV Research, Sydney, Australia
| | - M. Alali
- Centre for Virus Research, The Westmead Millennium Institute, University of Sydney, and The Australian National Centre for HIV Research, Sydney, Australia
| | - H. Naif
- Centre for Virus Research, The Westmead Millennium Institute, University of Sydney, and The Australian National Centre for HIV Research, Sydney, Australia
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44
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Mathy NL, Bannert N, Norley SG, Kurth R. Cutting edge: CD4 is not required for the functional activity of IL-16. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:4429-32. [PMID: 10779741 DOI: 10.4049/jimmunol.164.9.4429] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
IL-16 functions as a chemoattractant factor, inhibitor of HIV replication, and inducer of proinflammatory cytokine production. Previous studies have suggested that CD4 is the receptor for IL-16, because only CD4+ cells respond to IL-16 and both the anti-CD4 Ab OKT4 and soluble CD4 can block IL-16 function. However, these are only indirect evidence of a requirement for CD4, and to date a direct interaction between IL-16 and CD4 has not been shown. In this paper, we report that cells from CD4 knockout mice are as responsive to IL-16 as their CD4 wild-type equivalents in both assays testing for IL-16 function (chemotaxis and production of proinflammatory cytokines). In addition, the inhibitory effect of soluble CD4 on IL-16 function observed using CD4 wild type murine cells was not observed using CD4 knockout cells. These data demonstrate that CD4 is not required for IL-16 function and suggest that another molecule acts as the major receptor.
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Affiliation(s)
- N L Mathy
- Paul-Ehrlich Institute, Langen, Germany.
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