1
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MacNabb BW, Kline J. MHC cross-dressing in antigen presentation. Adv Immunol 2023; 159:115-147. [PMID: 37996206 DOI: 10.1016/bs.ai.2023.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
Dendritic cells (DCs) orchestrate T cell responses by presenting antigenic peptides on major histocompatibility complex (MHC) and providing costimulation and other instructive signals. Professional antigen presenting cells (APCs), including DCs, are uniquely capable of generating and presenting peptide antigens derived from exogenous proteins. In addition to these canonical cross-presentation and MHC-II presentation pathways, APCs can also display exogenous peptide/MHC (p/MHC) acquired from neighboring cells and extracellular vesicles (EVs). This process, known as MHC cross-dressing, has been implicated in the regulation of T cell responses in a variety of in vivo contexts, including allogeneic solid organ transplantation, tumors, and viral infection. Although the occurrence of MHC cross-dressing has been clearly demonstrated, the importance of this antigen presentation mechanism continues to be elucidated. The contribution of MHC cross-dressing to overall antigen presentation has been obfuscated by the fact that DCs express the same MHC alleles as all other cells in the host, making it difficult to distinguish p/MHC generated within the DC from p/MHC acquired from another cell. As a result, much of what is known about MHC cross-dressing comes from studies using allogeneic organ transplantation and bone marrow chimeric mice, though recent development of mice bearing conditional knockout MHC and β2-microglobulin alleles should facilitate substantial progress in the coming years. In this review, we highlight recent advances in our understanding of MHC cross-dressing and its role in activating T cell responses in various contexts, as well as the experimental insights into the mechanism by which it occurs.
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Affiliation(s)
- Brendan W MacNabb
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States.
| | - Justin Kline
- Department of Medicine, Committee on Immunology, and Committee on Cancer Biology, University of Chicago, Chicago, IL, United States.
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2
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He W, Gea-Mallorquí E, Colin-York H, Fritzsche M, Gillespie GM, Brackenridge S, Borrow P, McMichael AJ. Intracellular trafficking of HLA-E and its regulation. J Exp Med 2023; 220:214089. [PMID: 37140910 PMCID: PMC10165540 DOI: 10.1084/jem.20221941] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 03/13/2023] [Accepted: 04/17/2023] [Indexed: 05/05/2023] Open
Abstract
Interest in MHC-E-restricted CD8+ T cell responses has been aroused by the discovery of their efficacy in controlling simian immunodeficiency virus (SIV) infection in a vaccine model. The development of vaccines and immunotherapies utilizing human MHC-E (HLA-E)-restricted CD8+ T cell response requires an understanding of the pathway(s) of HLA-E transport and antigen presentation, which have not been clearly defined previously. We show here that, unlike classical HLA class I, which rapidly exits the endoplasmic reticulum (ER) after synthesis, HLA-E is largely retained because of a limited supply of high-affinity peptides, with further fine-tuning by its cytoplasmic tail. Once at the cell surface, HLA-E is unstable and is rapidly internalized. The cytoplasmic tail plays a crucial role in facilitating HLA-E internalization, which results in its enrichment in late and recycling endosomes. Our data reveal distinctive transport patterns and delicate regulatory mechanisms of HLA-E, which help to explain its unusual immunological functions.
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Affiliation(s)
- Wanlin He
- Nuffield Department of Medicine, Center for Immuno-Oncology, University of Oxford, Oxford, UK
| | - Ester Gea-Mallorquí
- Nuffield Department of Medicine, Center for Immuno-Oncology, University of Oxford, Oxford, UK
| | - Huw Colin-York
- Kennedy Institute of Rheumatology, University of Oxford , Oxford, UK
| | - Marco Fritzsche
- Kennedy Institute of Rheumatology, University of Oxford , Oxford, UK
| | - Geraldine M Gillespie
- Nuffield Department of Medicine, Center for Immuno-Oncology, University of Oxford, Oxford, UK
| | - Simon Brackenridge
- Nuffield Department of Medicine, Center for Immuno-Oncology, University of Oxford, Oxford, UK
| | - Persephone Borrow
- Nuffield Department of Medicine, Center for Immuno-Oncology, University of Oxford, Oxford, UK
| | - Andrew J McMichael
- Nuffield Department of Medicine, Center for Immuno-Oncology, University of Oxford, Oxford, UK
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3
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Lazarczyk MJ, Eyford BA, Varghese M, Arora H, Munro L, Warda T, Pfeifer CG, Sowa A, Dickstein DR, Rumbell T, Jefferies WA, Dickstein DL. The intracellular domain of major histocompatibility class-I proteins is essential for maintaining excitatory spine density and synaptic ultrastructure in the brain. Sci Rep 2023; 13:6448. [PMID: 37081001 PMCID: PMC10119172 DOI: 10.1038/s41598-023-30054-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 02/15/2023] [Indexed: 04/22/2023] Open
Abstract
Major histocompatibility complex class I (MHC-I) proteins are expressed in neurons, where they regulate synaptic plasticity. However, the mechanisms by which MHC-I functions in the CNS remains unknown. Here we describe the first structural analysis of a MHC-I protein, to resolve underlying mechanisms that explains its function in the brain. We demonstrate that Y321F mutation of the conserved cytoplasmic tyrosine-based endocytosis motif YXXΦ in MHC-I affects spine density and synaptic structure without affecting neuronal complexity in the hippocampus, a region of the brain intimately involved in learning and memory. Furthermore, the impact of the Y321F substitution phenocopies MHC-I knock-out (null) animals, demonstrating that reverse, outside-in signalling events sensing the external environment is the major mechanism that conveys this information to the neuron and this has a previously undescribed yet essential role in the regulation of synaptic plasticity.
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Affiliation(s)
- Maciej J Lazarczyk
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Department of Medical Direction and Quality, Division of Institutional Measures, University Hospitals of Geneva, Geneva, Switzerland
| | - Brett A Eyford
- Michael Smith Laboratories, The University of British Columbia, 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada
- The Vancouver Prostate Centre, Robert H.N. Ho Research Centre, Vancouver General Hospital, 2660 Oak Street, Vancouver, BC, V6H 3Z6, Canada
- Centre for Blood Research, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC, Canada
| | - Merina Varghese
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Hitesh Arora
- Michael Smith Laboratories, The University of British Columbia, 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada
- The Vancouver Prostate Centre, Robert H.N. Ho Research Centre, Vancouver General Hospital, 2660 Oak Street, Vancouver, BC, V6H 3Z6, Canada
- Department of Microbiology and Immunology, University of British Columbia, 1365 - 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Lonna Munro
- Michael Smith Laboratories, The University of British Columbia, 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada
- The Vancouver Prostate Centre, Robert H.N. Ho Research Centre, Vancouver General Hospital, 2660 Oak Street, Vancouver, BC, V6H 3Z6, Canada
- Department of Microbiology and Immunology, University of British Columbia, 1365 - 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
- Centre for Blood Research, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
- Department of Zoology, University of British Columbia, 2370 - 6270 University Blvd., Vancouver, BC, V6T 1Z4, Canada
- Department of Medical Genetics, Life Sciences Institute, 1364 - 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC, Canada
| | - Tahia Warda
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Cheryl G Pfeifer
- Michael Smith Laboratories, The University of British Columbia, 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada
- The Vancouver Prostate Centre, Robert H.N. Ho Research Centre, Vancouver General Hospital, 2660 Oak Street, Vancouver, BC, V6H 3Z6, Canada
- Department of Microbiology and Immunology, University of British Columbia, 1365 - 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
- Centre for Blood Research, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
- Department of Zoology, University of British Columbia, 2370 - 6270 University Blvd., Vancouver, BC, V6T 1Z4, Canada
- Department of Medical Genetics, Life Sciences Institute, 1364 - 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC, Canada
| | - Allison Sowa
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Daniel R Dickstein
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Timothy Rumbell
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Wilfred A Jefferies
- Michael Smith Laboratories, The University of British Columbia, 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada.
- The Vancouver Prostate Centre, Robert H.N. Ho Research Centre, Vancouver General Hospital, 2660 Oak Street, Vancouver, BC, V6H 3Z6, Canada.
- Department of Microbiology and Immunology, University of British Columbia, 1365 - 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
- Centre for Blood Research, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
- Department of Zoology, University of British Columbia, 2370 - 6270 University Blvd., Vancouver, BC, V6T 1Z4, Canada.
- Department of Medical Genetics, Life Sciences Institute, 1364 - 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC, Canada.
| | - Dara L Dickstein
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
- Department of Pathology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd, Bethesda, MD, 20814, USA.
- The Henry M. Jackson Foundation for the Advancement of Military Medicine Inc., Bethesda, MD, 20817, USA.
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Merchant M, Mata CP, Liu Y, Zhai H, Protasio AV, Modis Y. A bioactive phlebovirus-like envelope protein in a hookworm endogenous virus. SCIENCE ADVANCES 2022; 8:eabj6894. [PMID: 35544562 PMCID: PMC9094657 DOI: 10.1126/sciadv.abj6894] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 03/25/2022] [Indexed: 05/02/2023]
Abstract
Endogenous viral elements (EVEs), accounting for 15% of our genome, serve as a genetic reservoir from which new genes can emerge. Nematode EVEs are particularly diverse and informative of virus evolution. We identify Atlas virus-an intact retrovirus-like EVE in the human hookworm Ancylostoma ceylanicum, with an envelope protein genetically related to GN-GC glycoproteins from the family Phenuiviridae. A cryo-EM structure of Atlas GC reveals a class II viral membrane fusion protein fold not previously seen in retroviruses. Atlas GC has the structural hallmarks of an active fusogen. Atlas GC trimers insert into membranes with endosomal lipid compositions and low pH. When expressed on the plasma membrane, Atlas GC has cell-cell fusion activity. With its preserved biological activities, Atlas GC has the potential to acquire a cellular function. Our work reveals structural plasticity in reverse-transcribing RNA viruses.
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Affiliation(s)
- Monique Merchant
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
- Cambridge Institute of Therapeutic Immunology and Infectious Disease (CITIID), University of Cambridge School of Clinical Medicine, Cambridge CB2 0AW, UK
| | - Carlos P. Mata
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
- Cambridge Institute of Therapeutic Immunology and Infectious Disease (CITIID), University of Cambridge School of Clinical Medicine, Cambridge CB2 0AW, UK
| | - Yangci Liu
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
- Cambridge Institute of Therapeutic Immunology and Infectious Disease (CITIID), University of Cambridge School of Clinical Medicine, Cambridge CB2 0AW, UK
| | - Haoming Zhai
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
- Cambridge Institute of Therapeutic Immunology and Infectious Disease (CITIID), University of Cambridge School of Clinical Medicine, Cambridge CB2 0AW, UK
| | - Anna V. Protasio
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
- Christ’s College, University of Cambridge, St Andrew’s Street, Cambridge, CB2 3BU, UK
| | - Yorgo Modis
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
- Cambridge Institute of Therapeutic Immunology and Infectious Disease (CITIID), University of Cambridge School of Clinical Medicine, Cambridge CB2 0AW, UK
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5
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Carey BS, Poulton KV, Poles A. Factors affecting HLA expression: A review. Int J Immunogenet 2019; 46:307-320. [PMID: 31183978 DOI: 10.1111/iji.12443] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 04/26/2019] [Accepted: 05/03/2019] [Indexed: 12/22/2022]
Abstract
The detection and semiquantitative measurement of circulating human leucocyte antigen (HLA)-specific antibodies is essential for the management of patients before and after transplantation. In addition, the pretransplant cross-match to assess the reactivity of recipient HLA antibody against donor lymphocytes has long been the gold standard to prevent hyperacute rejection. Whilst both of these tests assume that recipient HLA-specific antibody is the only variable in the assessment of transplant risk, this is not the case. Transplant immunologists recognize that some HLA antigens are expressed at levels a magnitude lower than others (e.g., HLA-C, HLA-DQ), but within loci, and between different cell types there are many factors that influence HLA expression in both resting and activated cells. HLA is not usually expressed without the specific promoter proteins NLRC5, for HLA class I, and CIITA, for class II. The quantity of HLA protein production is then affected by factors including promoter region polymorphisms, alternative exon splice sites, methylation and microRNA-directed degradation. Different loci are influenced by multiple combinations of these control mechanisms making prediction of HLA regulation difficult, but an ability to measure the cellular expression of each HLA antigen, in conjunction with knowledge of circulating HLA-specific antibody, would lead to a more informed algorithm to assess transplant risk.
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Affiliation(s)
- B Sean Carey
- Histocompatibility and Immunogenetics, Combined Laboratory, University Hospitals Plymouth, Plymouth, UK
| | | | - Anthony Poles
- Histocompatibility and Immunogenetics, Combined Laboratory, University Hospitals Plymouth, Plymouth, UK
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6
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Abstract
Cross-presentation of internalized antigens by dendritic cells requires efficient delivery of Major Histocompatibility Complex (MHC) class I molecules to peptide-loading compartments. Strong evidence suggests that such loading can occur outside of the endoplasmic reticulum; however, the trafficking pathways and sources of class I molecules involved are poorly understood. Examination of non-professional, non-phagocytic cells has revealed a clathrin-independent, Arf6-dependent recycling pathway likely traveled by internalized optimally loaded (closed) class I molecules. Some closed and all open MHC class I molecules travel to late endosomes to be degraded but might also partly be re-loaded with peptides and recycled. Studies of viral interference revealed pathways in which class I molecules are directed to degradation in lysosomes upon ubiquitination at the surface, or upon AP-1 and HIV-nef-dependent misrouting from the Golgi network to lysosomes. While many observations made in non-professional cells remain to be re-examined in dendritic cells, available evidence suggests that both recycling and neo-synthesized class I molecules can be loaded with cross-presented peptides. Recycling molecules can be recruited to phagosomes triggered by innate signals such as TLR4 ligands, and may therefore specialize in loading with phagocytosed antigens. In contrast, AP-1-dependent accumulation at, or trafficking through, a Golgi compartment of newly synthesized molecules appears to be important for cross-presentation of soluble proteins and possibly of long peptides that are processed in the so-called vacuolar pathway. However, significant cell biological work will be required to confirm this or any other model and to integrate knowledge on MHC class I biochemistry and trafficking in models of CD8(+) T-cell priming by dendritic cells.
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Affiliation(s)
- Peter van Endert
- Institut National de la Santé et de la Recherche Médicale, Unité 1151, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France.,Centre National de la Recherche Scientifique, Unité 8253, Paris, France
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7
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Frietze KK, Pappy AL, Melson JW, O'Driscoll EE, Tyler CM, Perlman DH, Boulanger LM. Cryptic protein-protein interaction motifs in the cytoplasmic domain of MHCI proteins. BMC Immunol 2016; 17:24. [PMID: 27435737 PMCID: PMC4950430 DOI: 10.1186/s12865-016-0154-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 05/27/2016] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Major histocompatibility complex class I (MHCI) proteins present antigenic peptides for immune surveillance and play critical roles in nervous system development and plasticity. Most MHCI are transmembrane proteins. The extracellular domain of MHCI interacts with immunoreceptors, peptides, and co-receptors to mediate immune signaling. While the cytoplasmic domain also plays important roles in endocytic trafficking, cross-presentation of extracellularly derived antigens, and CTL priming, the molecular mediators of cytoplasmic signaling by MHCI remain largely unknown. RESULTS Here we show that the cytoplasmic domain of MHCI contains putative protein-protein interaction domains known as PDZ (PSD95/disc large/zonula occludens-1) ligands. PDZ ligands are motifs that bind to PDZ domains to organize and mediate signaling at cell-cell contacts. PDZ ligands are short, degenerate motifs, and are therefore difficult to identify via sequence homology alone, but several lines of evidence suggest that putative PDZ ligand motifs in MHCI are under positive selective pressure. Putative PDZ ligands are found in all of the 99 MHCI proteins examined from diverse species, and are enriched in the cytoplasmic domain, where PDZ interactions occur. Both the position of the PDZ ligand and the class of ligand motif are conserved across species, as well as among genes within a species. Non-synonymous substitutions, when they occur, frequently preserve the motif. Of the many specific possible PDZ ligand motifs, a handful are strikingly and selectively overrepresented in MHCI's cytoplasmic domain, but not elsewhere in the same proteins. Putative PDZ ligands in MHCI encompass conserved serine and tyrosine residues that are targets of phosphorylation, a post-translational modification that can regulate PDZ interactions. Finally, proof-of-principle in vitro interaction assays demonstrate that the cytoplasmic domains of particular MHCI proteins can bind directly and specifically to PDZ1 and PDZ4&5 of MAGI-1, and identify a conserved PDZ ligand motif in the classical MHCI H2-K that is required for this interaction. CONCLUSIONS These results identify cryptic protein interaction motifs in the cytoplasmic domain of MHCI. In so doing, they suggest that the cytoplasmic domain of MHCI could participate in previously unsuspected PDZ mediated protein-protein interactions at neuronal as well as immunological synapses.
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Affiliation(s)
- Karla K Frietze
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08544, USA
| | - Adlai L Pappy
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08544, USA
| | - Jack W Melson
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08544, USA
| | - Emily E O'Driscoll
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08544, USA
| | - Carolyn M Tyler
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08544, USA.,Princeton Neuroscience Institute, Princeton University, Princeton, NJ, 08544, USA
| | - David H Perlman
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08544, USA
| | - Lisa M Boulanger
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08544, USA. .,Princeton Neuroscience Institute, Princeton University, Princeton, NJ, 08544, USA.
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Bradley SD, Chen Z, Melendez B, Talukder A, Khalili JS, Rodriguez-Cruz T, Liu S, Whittington M, Deng W, Li F, Bernatchez C, Radvanyi LG, Davies MA, Hwu P, Lizée G. BRAFV600E Co-opts a Conserved MHC Class I Internalization Pathway to Diminish Antigen Presentation and CD8+ T-cell Recognition of Melanoma. Cancer Immunol Res 2015; 3:602-9. [PMID: 25795007 DOI: 10.1158/2326-6066.cir-15-0030] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 03/09/2015] [Indexed: 12/29/2022]
Abstract
Oncogene activation in tumor cells induces broad and complex cellular changes that contribute significantly to disease initiation and progression. In melanoma, oncogenic BRAF(V600E) has been shown to drive the transcription of a specific gene signature that can promote multiple mechanisms of immune suppression within the tumor microenvironment. We show here that BRAF(V600E) also induces rapid internalization of MHC class I (MHC-I) from the melanoma cell surface and its intracellular sequestration within endolysosomal compartments. Importantly, MAPK inhibitor treatment quickly restored MHC-I surface expression in tumor cells, thereby enhancing melanoma antigen-specific T-cell recognition and effector function. MAPK pathway-driven relocalization of HLA-A*0201 required a highly conserved cytoplasmic serine phosphorylation site previously implicated in rapid MHC-I internalization and recycling by activated immune cells. Collectively, these data suggest that oncogenic activation of BRAF allows tumor cells to co-opt an evolutionarily conserved MHC-I trafficking pathway as a strategy to facilitate immune evasion. This link between MAPK pathway activation and the MHC-I cytoplasmic tail has direct implications for immunologic recognition of tumor cells and provides further evidence to support testing therapeutic strategies combining MAPK pathway inhibition with immunotherapies in the clinical setting.
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Affiliation(s)
- Sherille D Bradley
- Department of Melanoma Medical Oncology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Zeming Chen
- Department of Melanoma Medical Oncology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Brenda Melendez
- Department of Melanoma Medical Oncology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Amjad Talukder
- Department of Melanoma Medical Oncology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Jahan S Khalili
- Department of Melanoma Medical Oncology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Tania Rodriguez-Cruz
- Department of Melanoma Medical Oncology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Shujuan Liu
- Department of Melanoma Medical Oncology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Mayra Whittington
- Department of Melanoma Medical Oncology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Wanleng Deng
- Department of Melanoma Medical Oncology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Fenge Li
- Department of Melanoma Medical Oncology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Chantale Bernatchez
- Department of Melanoma Medical Oncology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Laszlo G Radvanyi
- Department of Melanoma Medical Oncology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Michael A Davies
- Department of Melanoma Medical Oncology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Patrick Hwu
- Department of Melanoma Medical Oncology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Gregory Lizée
- Department of Melanoma Medical Oncology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas. Department of Immunology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas.
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9
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Montealegre S, Venugopalan V, Fritzsche S, Kulicke C, Hein Z, Springer S. Dissociation of β2-microglobulin determines the surface quality control of major histocompatibility complex class I molecules. FASEB J 2015; 29:2780-8. [PMID: 25782992 DOI: 10.1096/fj.14-268094] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 02/25/2015] [Indexed: 11/11/2022]
Abstract
Major histocompatibility complex class I proteins, which present antigenic peptides to cytotoxic T lymphocytes at the surface of all nucleated cells, are endocytosed and destroyed rapidly once their peptide ligand has dissociated. The molecular mechanism of this cellular quality control process, which prevents rebinding of exogenous peptides and thus erroneous immune responses, is unknown. To identify the nature of the decisive step in endocytic sorting of class I molecules and its location, we have followed the removal of optimally and suboptimally peptide-loaded murine H-2K(b) class I proteins from the cell surface. We find that the binding of their light chain, β2-microglobulin (β2m), protects them from endocytic destruction. Thus, the extended survival of suboptimally loaded K(b) molecules at 25°C is attributed to decreased dissociation of β2m. Because all forms of K(b) are constantly internalized but little β2m-receptive heavy chain is present at the cell surface, it is likely that β2m dissociation and recognition of the heavy chain for lysosomal degradation take place in an endocytic compartment.
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Affiliation(s)
- Sebastián Montealegre
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Vaishnavi Venugopalan
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Susanne Fritzsche
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Corinna Kulicke
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Zeynep Hein
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Sebastian Springer
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
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10
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Relationship between preparation of cells for therapy and cell quality using artificial neural network analysis. Artif Intell Med 2014; 62:119-27. [DOI: 10.1016/j.artmed.2014.07.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/29/2014] [Accepted: 07/12/2014] [Indexed: 11/23/2022]
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11
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Demachi-Okamura A, Torikai H, Akatsuka Y, Miyoshi H, Yoshimori T, Kuzushima K. Autophagy creates a CTL epitope that mimics tumor-associated antigens. PLoS One 2012; 7:e47126. [PMID: 23071732 PMCID: PMC3469533 DOI: 10.1371/journal.pone.0047126] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Accepted: 09/10/2012] [Indexed: 12/25/2022] Open
Abstract
The detailed mechanisms responsible for processing tumor-associated antigens and presenting them to CTLs remain to be fully elucidated. In this study, we demonstrate a unique CTL epitope generated from the ubiquitous protein puromycin-sensitive aminopeptidase, which is presented via HLA-A24 on leukemic and pancreatic cancer cells but not on normal fibroblasts or EBV-transformed B lymphoblastoid cells. The generation of this epitope requires proteasomal digestion and transportation from the endoplasmic reticulum to the Golgi apparatus and is sensitive to chloroquine-induced inhibition of acidification inside the endosome/lysosome. Epitope liberation depends on constitutively active autophagy, as confirmed with immunocytochemistry for the autophagosome marker LC3 as well as RNA interference targeting two different autophagy-related genes. Therefore, ubiquitously expressed proteins may be sources of specific tumor-associated antigens when processed through a unique mechanism involving autophagy.
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Affiliation(s)
- Ayako Demachi-Okamura
- Division of Immunology, Aichi Cancer Center Research Institute, Nagoya, Japan
- * E-mail: (ADO); (KK)
| | - Hiroki Torikai
- Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Yoshiki Akatsuka
- Division of Immunology, Aichi Cancer Center Research Institute, Nagoya, Japan
- Department of Hematology and Oncology, Fujita Health University, Toyoake, Japan
| | - Hiroyuki Miyoshi
- Subteam for Manipulation of Cell Fate, RIKEN BioResource Center, Tsukuba, Japan
| | - Tamotsu Yoshimori
- Department of Genetics, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Kiyotaka Kuzushima
- Division of Immunology, Aichi Cancer Center Research Institute, Nagoya, Japan
- Department of Cellular Oncology, Nagoya University Graduate School of Medicine, Nagoya, Japan
- * E-mail: (ADO); (KK)
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12
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Endogenous viral antigen processing generates peptide-specific MHC class I cell-surface clusters. Proc Natl Acad Sci U S A 2012; 109:15407-12. [PMID: 22949678 DOI: 10.1073/pnas.1208696109] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sensitivity is essential in CD8+ T-cell killing of virus-infected cells and tumor cells. Although the affinity of the T-cell receptor (TCR) for antigen is relatively low, the avidity of T cell-antigen-presenting cell interactions is greatly enhanced by increasing the valence of the interaction. It is known that TCRs cluster into protein islands after engaging their cognate antigen (peptides bound to MHC molecules). Here, we show that mouse K(b) class I molecules segregate into preformed, long-lasting (hours) clusters on the antigen-presenting cell surface based on their bound viral peptide. Peptide-specific K(b) clustering occurs when source antigens are expressed by vaccinia or vesicular stomatitis virus, either as proteasome-liberated precursors or free intracellular peptides. By contrast, K(b)-peptide complexes generated by incubating cells with synthetic peptides are extensively intermingled on the cell surface. Peptide-specific complex sorting is first detected in the Golgi complex, and compromised by removing the K(b) cytoplasmic tail. Peptide-specific clustering is associated with increased T-cell sensitivity: on a per-complex basis, endogenous SIINFEKL activates T cells more efficiently than synthetic SIINFEKL, and wild-type K(b) presents endogenous SIINFEKL more efficiently than tailless K(b). We propose that endogenous processing generates peptide-specific clusters of class I molecules to maximize the sensitivity and speed of T-cell immunosurveillance.
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13
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Compeer EB, Flinsenberg TWH, van der Grein SG, Boes M. Antigen processing and remodeling of the endosomal pathway: requirements for antigen cross-presentation. Front Immunol 2012; 3:37. [PMID: 22566920 PMCID: PMC3342355 DOI: 10.3389/fimmu.2012.00037] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Accepted: 02/16/2012] [Indexed: 12/29/2022] Open
Abstract
Cross-presentation of endocytosed antigen as peptide/class I major histocompatibility complex complexes plays a central role in the elicitation of CD8+ T cell clones that mediate anti-viral and anti-tumor immune responses. While it has been clear that there are specific subsets of professional antigen presenting cells capable of antigen cross-presentation, identification of mechanisms involved is still ongoing. Especially amongst dendritic cells (DC), there are specialized subsets that are highly proficient at antigen cross-presentation. We here present a focused survey on the cell biological processes in the endosomal pathway that support antigen cross-presentation. This review highlights DC-intrinsic mechanisms that facilitate the cross-presentation of endocytosed antigen, including receptor-mediated uptake, maturation-induced endosomal sorting of membrane proteins, dynamic remodeling of endosomal structures and cell surface-directed endosomal trafficking. We will conclude with the description of pathogen-induced deviation of endosomal processing, and discuss how immune evasion strategies pertaining endosomal trafficking may preclude antigen cross-presentation.
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Affiliation(s)
- Ewoud Bernardus Compeer
- Department of Pediatric Immunology, University Medical Center Utrecht/Wilhelmina Children's Hospital Utrecht, Netherlands
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14
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Peters HL, Tuli A, Sharma M, Naslavsky N, Caplan S, MacDonald RG, Solheim JC. Regulation of major histocompatibility complex class I molecule expression on cancer cells by amyloid precursor-like protein 2. Immunol Res 2012; 51:39-44. [PMID: 21826533 DOI: 10.1007/s12026-011-8238-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The three members of the amyloid precursor protein family in mammals [amyloid precursor protein, amyloid precursor-like protein 1, and amyloid precursor-like protein 2 (APLP2)] have been implicated in a large array of intracellular processes, which include development, transcription, apoptosis, metabolism, and the cell cycle. A series of studies by our laboratories has demonstrated that APLP2 is highly expressed by many cancer cell lines (with the highest expression in pancreatic cancer cell lines) and that it facilitates major histocompatibility complex (MHC) class I molecule endocytosis. This review focuses on this recently revealed function of APLP2 relevant to tumor immunology: that it acts as a novel regulator of MHC class I molecule surface expression.
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Affiliation(s)
- Haley L Peters
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA
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15
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STAGSTED JAN. Journey beyond immunology. Regulation of receptor internalization by major histocompatibility complex class I (MHC-I) and effect of peptides derived from MHC-I. APMIS 2011. [DOI: 10.1111/j.1600-0463.1998.tb05657.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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16
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Rodríguez-Cruz TG, Liu S, Khalili JS, Whittington M, Zhang M, Overwijk W, Lizée G. Natural splice variant of MHC class I cytoplasmic tail enhances dendritic cell-induced CD8+ T-cell responses and boosts anti-tumor immunity. PLoS One 2011; 6:e22939. [PMID: 21860662 PMCID: PMC3157908 DOI: 10.1371/journal.pone.0022939] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 07/01/2011] [Indexed: 11/22/2022] Open
Abstract
Dendritic cell (DC)-mediated presentation of MHC class I (MHC-I)/peptide complexes is a crucial first step in the priming of CTL responses, and the cytoplasmic tail of MHC-I plays an important role in modulating this process. Several species express a splice variant of the MHC-I tail that deletes exon 7-encoding amino acids (Δ7), including a conserved serine phosphorylation site. Previously, it has been shown that Δ7 MHC-I molecules demonstrate extended DC surface half-lives, and that mice expressing Δ7-Kb generate significantly augmented CTL responses to viral challenge. Herein, we show that Δ7-Db-expressing DCs stimulated significantly more proliferation and much higher cytokine secretion by melanoma antigen-specific (Pmel-1) T cells. Moreover, in combination with adoptive Pmel-1 T-cell transfer, Δ7-Db DCs were superior to WT-Db DCs at stimulating anti-tumor responses against established B16 melanoma tumors, significantly extending mouse survival. Human DCs engineered to express Δ7-HLA-A*0201 showed similarly enhanced CTL stimulatory capacity. Further studies demonstrated impaired lateral membrane movement and clustering of human Δ7-MHC-I/peptide complexes, resulting in significantly increased bioavailability of MHC-I/peptide complexes for specific CD8+ T cells. Collectively, these data suggest that targeting exon 7-encoded MHC-I cytoplasmic determinants in DC vaccines has the potential to increase CD8+ T-cell stimulatory capacity and substantially improve their clinical efficacy.
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Affiliation(s)
- Tania G. Rodríguez-Cruz
- Departments of Melanoma Medical Oncology and Immunology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Shujuan Liu
- Departments of Melanoma Medical Oncology and Immunology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Jahan S. Khalili
- Departments of Melanoma Medical Oncology and Immunology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Mayra Whittington
- Departments of Melanoma Medical Oncology and Immunology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Minying Zhang
- Departments of Melanoma Medical Oncology and Immunology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Willem Overwijk
- Departments of Melanoma Medical Oncology and Immunology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Gregory Lizée
- Departments of Melanoma Medical Oncology and Immunology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
- * E-mail:
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17
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Cho S, Ryoo J, Jun Y, Ahn K. Receptor-Mediated ER Export of Human MHC Class I Molecules Is Regulated by the C-Terminal Single Amino Acid. Traffic 2010; 12:42-55. [DOI: 10.1111/j.1600-0854.2010.01132.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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18
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Jin YC, Wei P, Wei XX, Zhao ZY, Li Y. Rapid detection of BF haplotypes by a semi-nested polymerase chain reaction, which causes resistance/susceptibility to Marek's disease in chicken. Scand J Immunol 2010; 72:94-7. [PMID: 20618767 DOI: 10.1111/j.1365-3083.2010.02415.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A semi-nested polymerase chain reaction (snPCR) assay was developed for the rapid detection of resistant/susceptible BF haplotypes to Marek's disease (MD) using the cDNA samples from peripheral blood leucocytes, liver, spleen and heart from Xiayan homozygous chickens: A(11), C(23), D(8) and D(12) (resistant to MD), A(5) and B(21) (susceptible to MD). The snPCR was utilized to span alternative splicing-out of the sequence encoding the second segment of the cytoplasmic part of the mature BF molecules (exon 7). This alternative exon 7 splice variant was detected in BF*A(5) and BF*B(21) (susceptible to MD), but not in the MD-resistant BF*A(11), BF*C(23), BF*D(8) and BF*D(12) haplotypes, suggesting a potential role of exon 7 for the detection of resistant/susceptible BF haplotypes to MD.
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Affiliation(s)
- Y-C Jin
- Poultry Science and Health, Guangxi University, Nanning, China
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19
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Tuli A, Sharma M, Capek HL, Naslavsky N, Caplan S, Solheim JC. Mechanism for amyloid precursor-like protein 2 enhancement of major histocompatibility complex class I molecule degradation. J Biol Chem 2009; 284:34296-307. [PMID: 19808674 DOI: 10.1074/jbc.m109.039727] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Earlier studies have demonstrated interaction of the murine major histocompatibility complex (MHC) class I molecule K(d) with amyloid precursor-like protein 2 (APLP2), a ubiquitously expressed member of the amyloid precursor protein family. Our current findings indicate that APLP2 is internalized in a clathrin-dependent manner, as shown by utilization of inhibitors of the clathrin pathway. Furthermore, we demonstrated that APLP2 and K(d) bind at the cell surface and are internalized together. The APLP2 cytoplasmic tail contains two overlapping consensus motifs for binding to the adaptor protein-2 complex, and mutation of a tyrosine shared by both motifs severely impaired APLP2 internalization and ability to promote K(d) endocytosis. Upon increased expression of wild type APLP2, K(d) molecules were predominantly directed to the lysosomes rather than recycled to the plasma membrane. These findings suggest a model in which APLP2 binds K(d) at the plasma membrane, facilitates uptake of K(d) in a clathrin-dependent manner, and routes the endocytosed K(d) to the lysosomal degradation pathway. Thus, APLP2 has a multistep trafficking function that influences the expression of major histocompatibility complex class I molecules at the plasma membrane.
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Affiliation(s)
- Amit Tuli
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6805, USA
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20
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Boes M, Stoppelenburg AJ, Sillé FCM. Endosomal processing for antigen presentation mediated by CD1 and Class I major histocompatibility complex: roads to display or destruction. Immunology 2009; 127:163-70. [PMID: 19476512 DOI: 10.1111/j.1365-2567.2009.03078.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The presentation of antigen in a form that can be recognized by T lymphocytes of the immune system requires antigen processing and association of antigen-derived fragments with molecules encoded by the major histocompatibility complex (MHC) locus or by the CD1 locus. Much emphasis on antigen processing and presentation in the last decades has focused on what we consider 'conventional routes' of antigen processing and presentation, whereby extracellular antigens are processed for presentation via Class II MHC complexes and cytosolic antigens are presented as peptide-Class I MHC complexes. We here highlight two other pathways in myeloid dendritic cells, those of lipid antigen presentation in association with CD1 and of peptide cross-presentation via Class I MHC complexes. Some pathogens evade immune recognition through inhibition of antigen presentation of phagosomal origin. Deviations in endosomal antigen processing and presentation are also seen in individuals suffering from glycosphingolipid lysosomal lipid storage diseases. We summarize recent developments in the endosomal antigen processing and presentation pathway, for display as lipid-CD1 complexes to natural killer T cells and as peptide-Class I MHC complexes to CD8 T cells.
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Affiliation(s)
- Marianne Boes
- Department of Pediatric Immunology, University Medical Center Utrecht, Wilhelmina Children's Hospital, the Netherlands.
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21
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Knorr R, Karacsonyi C, Lindner R. Endocytosis of MHC molecules by distinct membrane rafts. J Cell Sci 2009; 122:1584-94. [PMID: 19383725 DOI: 10.1242/jcs.039727] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
In B-lymphocytes, endocytosis of MHC I and MHC II molecules is important for the cross-priming and presentation of labile antigens, respectively. Here, we report that MHC I and MHC II were internalized by separate endocytic carriers that lacked transferrin receptor. Cholera toxin B was co-internalized with MHC II, but not with MHC I, suggesting that the CLIC/GEEC pathway is involved in the uptake of MHC II. Endocytosis of MHC I and MHC II was inhibited by filipin, but only MHC II showed a strong preference for a membrane raft environment in a co-clustering analysis with G(M)1. By using a novel method for the extraction of detergent-resistant membranes (DRMs), we observed that MHC I and MHC II associate with two distinct types of DRMs. These differ in density, protein content, lipid composition, and ultrastructure. The results of cell surface biotinylation and subsequent DRM isolation show that precursors for both DRMs coexist in the plasma membrane. Moreover, clustering of MHC proteins at the cell surface resulted in shifts of the respective DRMs, revealing proximity-induced changes in the membrane environment. Our results suggest that the preference of MHC I and MHC II for distinct membrane rafts directs them to different cellular entry points.
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Affiliation(s)
- Ruth Knorr
- Department of Cell Biology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
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22
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Basha G, Lizée G, Reinicke AT, Seipp RP, Omilusik KD, Jefferies WA. MHC class I endosomal and lysosomal trafficking coincides with exogenous antigen loading in dendritic cells. PLoS One 2008; 3:e3247. [PMID: 18802471 PMCID: PMC2532750 DOI: 10.1371/journal.pone.0003247] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Accepted: 08/29/2008] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Cross-presentation by dendritic cells (DCs) is a crucial prerequisite for effective priming of cytotoxic T-cell responses against bacterial, viral and tumor antigens; however, this antigen presentation pathway remains poorly defined. METHODOLOGY/PRINCIPAL FINDINGS In order to develop a comprehensive understanding of this process, we tested the hypothesis that the internalization of MHC class I molecules (MHC-I) from the cell surface is directly involved in cross-presentation pathway and the loading of antigenic peptides. Here we provide the first examination of the internalization of MHC-I in DCs and we demonstrate that the cytoplasmic domain of MHC-I appears to act as an addressin domain to route MHC-I to both endosomal and lysosomal compartments of DCs, where it is demonstrated that loading of peptides derived from exogenously-derived proteins occurs. Furthermore, by chasing MHC-I from the cell surface of normal and transgenic DCs expressing mutant forms of MHC-I, we observe that a tyrosine-based endocytic trafficking motif is required for the constitutive internalization of MHC-I molecules from the cell surface into early endosomes and subsequently deep into lysosomal peptide-loading compartments. Finally, our data support the concept that multiple pathways of peptide loading of cross-presented antigens may exist depending on the chemical nature and size of the antigen requiring processing. CONCLUSIONS/SIGNIFICANCE We conclude that DCs have 'hijacked' and adapted a common vacuolar/endocytic intracellular trafficking pathway to facilitate MHC I access to the endosomal and lysosomal compartments where antigen processing and loading and antigen cross-presentation takes place.
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Affiliation(s)
- Genc Basha
- Biomedical Research Centre, Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
- Biomedical Research Centre, Michael Smith Laboratories, Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
- Biomedical Research Centre, Michael Smith Laboratories, Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Gregory Lizée
- Biomedical Research Centre, Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
- Biomedical Research Centre, Michael Smith Laboratories, Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
- Biomedical Research Centre, Michael Smith Laboratories, Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Anna T. Reinicke
- Biomedical Research Centre, Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
- Biomedical Research Centre, Michael Smith Laboratories, Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
- Biomedical Research Centre, Michael Smith Laboratories, Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Robyn P. Seipp
- Biomedical Research Centre, Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
- Biomedical Research Centre, Michael Smith Laboratories, Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
- Biomedical Research Centre, Michael Smith Laboratories, Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Kyla D. Omilusik
- Biomedical Research Centre, Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
- Biomedical Research Centre, Michael Smith Laboratories, Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
- Biomedical Research Centre, Michael Smith Laboratories, Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Wilfred A. Jefferies
- Biomedical Research Centre, Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
- Biomedical Research Centre, Michael Smith Laboratories, Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
- Biomedical Research Centre, Michael Smith Laboratories, Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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23
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Tuli A, Sharma M, McIlhaney MM, Talmadge JE, Naslavsky N, Caplan S, Solheim JC. Amyloid precursor-like protein 2 increases the endocytosis, instability, and turnover of the H2-K(d) MHC class I molecule. THE JOURNAL OF IMMUNOLOGY 2008; 181:1978-87. [PMID: 18641335 DOI: 10.4049/jimmunol.181.3.1978] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The defense against the invasion of viruses and tumors relies on the presentation of viral and tumor-derived peptides to CTL by cell surface MHC class I molecules. Previously, we showed that the ubiquitously expressed protein amyloid precursor-like protein 2 (APLP2) associates with the folded form of the MHC class I molecule K(d). In the current study, APLP2 was found to associate with folded K(d) molecules following their endocytosis and to increase the amount of endocytosed K(d). In addition, increased expression of APLP2 was shown to decrease K(d) surface expression and thermostability. Correspondingly, K(d) thermostability and surface expression were increased by down-regulation of APLP2 expression. Overall, these data suggest that APLP2 modulates the stability and endocytosis of K(d) molecules.
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Affiliation(s)
- Amit Tuli
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
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24
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Gruda R, Achdout H, Stern-Ginossar N, Gazit R, Betser-Cohen G, Manaster I, Katz G, Gonen-Gross T, Tirosh B, Mandelboim O. Intracellular cysteine residues in the tail of MHC class I proteins are crucial for extracellular recognition by leukocyte Ig-like receptor 1. THE JOURNAL OF IMMUNOLOGY 2007; 179:3655-61. [PMID: 17785801 DOI: 10.4049/jimmunol.179.6.3655] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The activity of NK cells is regulated by activating receptors that recognize mainly stress-induced ligands and by inhibitory receptors that recognize mostly MHC class I proteins on target cells. Comparing the cytoplasmic tail sequences of various MHC class I proteins revealed the presence of unique cysteine residues in some of the MHC class I molecules which are absent in others. To study the role of these unique cysteines, we performed site specific mutagenesis, generating MHC class I molecules lacking these cysteines, and demonstrated that their expression on the cell surface was impaired. Surprisingly, we demonstrated that these cysteines are crucial for the surface binding of the leukocyte Ig-like receptor 1 inhibitory receptor to the MHC class I proteins, but not for the binding of the KIR2DL1 inhibitory receptor. In addition, we demonstrated that the cysteine residues in the cytoplasmic tail of MHC class I proteins are crucial for their egress from the endoplasmic reticulum and for their palmitoylation, thus probably affecting their expression on the cell surface. Finally, we show that the cysteine residues are important for proper extracellular conformation. Thus, although the interaction between leukocyte Ig-like receptor 1 and MHC class I proteins is formed between two extracellular surfaces, the intracellular components of MHC class I proteins play a crucial role in this recognition.
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Affiliation(s)
- Raizy Gruda
- Lautenberg Center for General and Tumor Immunology, Hebrew University, Hadassah Medical School, Jerusalem, Israel
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25
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Tiwari N, Garbi N, Reinheckel T, Moldenhauer G, Hämmerling GJ, Momburg F. A transporter associated with antigen-processing independent vacuolar pathway for the MHC class I-mediated presentation of endogenous transmembrane proteins. THE JOURNAL OF IMMUNOLOGY 2007; 178:7932-42. [PMID: 17548631 DOI: 10.4049/jimmunol.178.12.7932] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
MHC class I molecules present peptides derived from the ectodomains of endogenous transmembrane proteins; however, the processing of these Ags is incompletely understood. As model transmembrane Ags we investigated the processing of MHC-I-derived fusion proteins containing the N-terminally extended K(b)-restricted OVA epitope SIINFEKL in the extracytoplasmic domain. In TAP-deficient, nonprofessional APCs, the epitope was cleaved out of various sequence contexts and presented to T cells. Ag presentation was inhibited by acidophilic amines and inhibitors of the vacuolar proton pump, indicating processing in endosomes. Endosomal aspartic-type cathepsins, and to some extent also the trans-Golgi network protease furin, were involved in processing. Clathrin-dependent and independent internalization from the cell surface targeted MHC-I fusion proteins to early and late endosomes, where SIINFEKL/K(b) complexes were detected by immunofluorescence microscopy. Targeting of MHC-I fusion proteins to processing compartments was independent of sequence motifs in the cytoplasmic tail. Not only TAP-deficient cells, but also TAP-competent APCs used the vacuolar pathway for processing of MHC-I fusion proteins. Thus, endosomal processing of internalized endogenous transmembrane proteins represents a novel alternate pathway for the generation of MHC-I-binding peptides.
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Affiliation(s)
- Neeraj Tiwari
- Department of Molecular Immunology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
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26
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Uhles S, Moede T, Leibiger B, Berggren PO, Leibiger IB. Selective gene activation by spatial segregation of insulin receptor B signaling. FASEB J 2007; 21:1609-21. [PMID: 17264162 DOI: 10.1096/fj.06-7589com] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Insulin exerts pleiotropic effects at the cellular level. Signaling via the two isoforms of the insulin receptor (IR) may explain the activation of different signaling cascades, while it remains to be explored how selectivity is achieved when utilizing the same IR isoform. We now demonstrate that insulin-stimulated transcription of c-fos and glucokinase genes is activated simultaneously in the insulin-producing beta-cell via IR-B localized in different cellular compartments. Insulin activates the glucokinase gene from plasma membrane-standing IR-B, while c-fos gene activation is dependent on clathrin-mediated IR-B-endocytosis and signaling from early endosomes. Moreover, glucokinase gene up-regulation requires the integrity of the juxtamembrane IR-B NPEY-motif and signaling via PI3K-C2alpha-like/PDK1/PKB, while c-fos gene activation requires the intact C-terminal YTHM-motif and signaling via PI3K Ia/Shc/MEK1/ERK. By using IR-B as an example it is thus possible to demonstrate how spatial segregation allows simultaneous and selective signaling via the same receptor isoform in the same cell.
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Affiliation(s)
- Sabine Uhles
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, S-171 76 Stockholm, Sweden
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27
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Arosa FA, Santos SG, Powis SJ. Open conformers: the hidden face of MHC-I molecules. Trends Immunol 2007; 28:115-23. [PMID: 17261379 DOI: 10.1016/j.it.2007.01.002] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Revised: 12/13/2006] [Accepted: 01/17/2007] [Indexed: 10/23/2022]
Abstract
A pool of MHC-I molecules present at the plasma membrane can dissociate from the peptide and/or the light chain, becoming open MHC-I conformers. Whereas peptide-bound MHC-I molecules have an important role in regulating adaptive and innate immune responses, through trans-interactions with T cell and NK cell receptors, the function of the open MHC-I conformers is less clear but seems to be related to their inherent ability to cis-associate, both with themselves and with other receptors. Here, we review data indicating the open MHC-I conformers as regulators of ligand-receptor interactions and discuss the biological implications for immune and non-immune cells. The likelihood that the MHC-I heavy chains have hidden functions that are determined by the amino acid sequence of the alpha1 and alpha2 domains are discussed.
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Affiliation(s)
- Fernando A Arosa
- Lymphocyte Biology Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, 4150-180 Porto, Portugal.
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28
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Abstract
Classical major histocompatibility complex (MHC) class I antigens are trimeric molecules found on the surface of nucleated cells in all jawed vertebrates. MHC I are recognised by two families of receptors: clonotypic T cell receptors expressed on the surface of CD8+ cytotoxic T lymphocytes (CTLs), and monomorphic receptors expressed by both natural killer cells and CTLs. The production of MHC I molecules within the cells is a sequential process performed with the help of interacting proteins: proteases, chaperones, transporters and so on. Although largely homologous in their structure, organisation and function, the human and mouse MHC I antigen processing and presentation machineries show fine differences. Transgenesis and 'knockout' or 'knock-in' technologies permit the addition of relevant human genes or the replacement of mouse genes by their human orthologues in order to produce immunologically humanised mice. Such experimental animals are especially relevant for the comparative evaluation of immunotherapies and for the characterisation of MHC I peptide epitopes. This review presents the similarities and differences between mouse and human MHC I antigen processing machinery, and describes the development and utilisation of improving mouse models of human cytotoxic T cell immunity.
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Affiliation(s)
- Steve Pascolo
- Department of Immunology, University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany.
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Dalgaard TS, Vitved L, Skjødt K, Thomsen B, Labouriau R, Jensen KH, Juul-Madsen HR. Molecular Characterization of Major Histocompatibility Complex Class I (B-F) mRNA Variants from Chickens Differing in Resistance to Marek's Disease. Scand J Immunol 2005; 62:259-70. [PMID: 16179013 DOI: 10.1111/j.1365-3083.2005.01652.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this study, the relative distributions of two alternatively polyadenylated chicken major histocompatibility complex (MHC) mRNA isoforms of approximately 1.5 and 1.9 kb were analysed in spleen cells from chickens homozygous for the MHC haplotypes B21 and B19v1 as well as in heterozygous B19v1/B21 birds. Both isoforms are likely to encode classical MHC class I (B-F) alpha chains. The B19v1 and B21 MHC haplotypes confer different levels of protection against Marek's disease (MD), which is caused by infection with MD virus (MDV). In spleen cells, MD-resistant B21 birds were shown to have the highest percentage of the 1.5 kb variant relative to the total MHC class I expression, MD-susceptible B19v1 birds the lowest and B19v1/B21 birds an intermediate percentage. Infection of 4-week-old chickens with the GA strain of MDV was shown to cause a significant increase in the relative amount of 1.5 kb transcripts in B21 birds 32 days postinfection (dpi). Alternatively polyadenylated mRNA isoforms may encode identical proteins, but differences in the 3' untranslated region (UTR) can influence polyadenylation, mRNA stability, intracellular localization and translation efficiency. It was shown that the increased 1.5 kb percentage in B21 birds 32 days postinfection may be a result of a change in the choice of poly(A) site rather than a locus-specific upregulated transcription of the BF1 gene that preferentially expresses the 1.5 kb variant. Furthermore, the 3' end of the 1.5 kb mRNA variants deriving from B19v1 and B21 chickens was characterized by Rapid Amplification of cDNA Ends (RACE) and sequencing. No potentially functional elements were identified in the 3' UTR of the RACE products corresponding to this short isoform. However, variation in polyadenylation site was observed between the BF1 and BF2 mRNA transcripts and alternative splicing-out of the sequence (exon 7) encoding the second segment of the cytoplasmic part of the mature BF2*19 molecules. This alternative exon 7 splice variant was also detected in other MD-susceptible haplotypes, but not in the MD-resistant B21 and B21-like haplotypes, suggesting a potential role of exon 7 in MHC-related MD resistance.
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Affiliation(s)
- T S Dalgaard
- Department of Animal Health, Welfare and Nutrition, Danish Institute of Agricultural Sciences, Research Centre Foulum, Tjele, Denmark.
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30
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Guermonprez P, Amigorena S. Pathways for antigen cross presentation. ACTA ACUST UNITED AC 2004; 26:257-71. [PMID: 15592842 DOI: 10.1007/s00281-004-0176-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2004] [Accepted: 08/15/2004] [Indexed: 10/26/2022]
Abstract
Dendritic cells (DCs) have the unique ability to capture cellular tissue antigens, and to present them on MHC class I molecules to antigen-specific CD8(+) T lymphocytes after migration to the draining lymph nodes. This process, called "cross presentation" can lead either to the tolerization or activation of antigen-specific CD8(+) T cells. Antigen capture is believed to occur by phagocytosis of antigen-bearing dead cells. Recent studies suggest that the antigen transferred from the phagocytosed cell to the DC during cross presentation is a proteasome substrate, rather than a proteasomal degradation product. In most cases, the formation of the peptide-MHC class I complexes in DCs requires the export of protein antigens from phagosomes to the cytosol, where they undergo proteasomal degradation. The resulting peptides are then translocated by TAP to the lumen of a cross presentation-loading compartment, for association to MHC class I under the control of chaperones and oxido-reductases. This loading compartment may be either the endoplasmic reticulum (ER) or a mix phagosome-ER compartment. MHC class I egress from the loading compartment to cell surface remains to be analyzed.
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31
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Mesa CM, Thulien KJ, Moon DA, Veniamin SM, Magor KE. The dominant MHC class I gene is adjacent to the polymorphic TAP2 gene in the duck, Anas platyrhynchos. Immunogenetics 2004; 56:192-203. [PMID: 15205935 DOI: 10.1007/s00251-004-0672-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2003] [Revised: 03/16/2004] [Indexed: 01/03/2023]
Abstract
We are investigating the expression and linkage of major histocompatibility complex (MHC) class I genes in the duck ( Anas platyrhynchos) with a view toward understanding the susceptibility of ducks to two medically important viruses: influenza A and hepatitis B. In mammals, there are multiple MHC class I loci, and alleles at a locus are polymorphic and co-dominantly expressed. In contrast, in lower vertebrates the expression of one locus predominates. Southern-blot analysis and amplification of genomic sequences suggested that ducks have at least four loci encoding MHC class I. To identify expressed MHC genes, we constructed an unamplified cDNA library from the spleen of a single duck and screened for MHC class I. We sequenced 44 positive clones and identified four MHC class I sequences, each sharing approximately 85% nucleotide identity. Allele-specific oligonucleotide hybridization to a Northern blot indicated that only two of these sequences were abundantly expressed. In chickens, the dominantly expressed MHC class I gene lies adjacent to the transporter of antigen processing ( TAP2) gene. To investigate whether this organization is also found in ducks, we cloned the gene encoding TAP2 from the cDNA library. PCR amplification from genomic DNA allowed us to determine that the dominantly expressed MHC class I gene was adjacent to TAP2. Furthermore, we amplified two alleles of the TAP2 gene from this duck that have significant and clustered amino acid differences that may influence the peptides transported. This organization has implications for the ability of ducks to eliminate viral pathogens.
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Affiliation(s)
- Christine M Mesa
- Department of Biological Sciences, University of Alberta, CW405 Biological Sciences Building, AB T6G 2E9, Edmonton, Canada
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32
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Araki M, Wharton RP, Tang Z, Yu H, Asano M. Degradation of origin recognition complex large subunit by the anaphase-promoting complex in Drosophila. EMBO J 2004; 22:6115-26. [PMID: 14609957 PMCID: PMC275432 DOI: 10.1093/emboj/cdg573] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The initiation of DNA synthesis is thought to occur at sites bound by a heteromeric origin recognition complex (ORC). Previously, we have shown that in Drosophila, the level of the large subunit, ORC1, is modulated during cell cycle progression and that changes in ORC1 concentration alter origin utilization during development. Here, we investigate the mechanisms underlying cell cycle-dependent degradation of ORC1. We show that signals in the non-conserved N-terminal domain of ORC1 mediate its degradation upon exit from mitosis and in G1 phase by the anaphase-promoting complex (APC) in vivo. Degradation appears to be the result of direct action of the APC, as the N-terminal domain is ubiquitylated by purified APC in vitro. This regulated proteolysis is potent, sufficient to generate a normal temporal distribution of protein even when transcription of ORC1 is driven by strong constitutive promoters. These observations suggest that in Drosophila, ORC1 regulates origin utilization much as does Cdc6 in budding yeast.
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Affiliation(s)
- Marito Araki
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
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33
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Lizée G, Basha G, Tiong J, Julien JP, Tian M, Biron KE, Jefferies WA. Control of dendritic cell cross-presentation by the major histocompatibility complex class I cytoplasmic domain. Nat Immunol 2003; 4:1065-73. [PMID: 14566337 DOI: 10.1038/ni989] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2003] [Accepted: 09/29/2003] [Indexed: 11/09/2022]
Abstract
Dendritic cells (DCs) can present extracellularly derived antigens in the context of major histocompatibility complex (MHC) class I molecules, a process called cross-presentation. Although recognized to be important for priming of T cell responses to many viral, bacterial and tumor antigens, the mechanistic details of this alternative antigen-presentation pathway are poorly understood. We demonstrate here the existence of an endolysosomal compartment in DCs where exogenously derived peptides can be acquired for presentation to T cells, and show that the MHC class I cytoplasmic domain contains a tyrosine-based targeting signal required for routing MHC class I molecules through these compartments. We also report that transgenic mice expressing H-2K(b) with a tyrosine mutation mount inferior H-2K(b)-restricted cytotoxic T lymphocyte responses against two immunodominant viral epitopes, providing evidence of a crucial function for cross-priming in antiviral immunity.
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Affiliation(s)
- Gregory Lizée
- Biotechnology Laboratory, Biomedical Research Centre, and the Department of Medical Genetics, University of British Columbia, Vancouver, Canada V6T 1Z3
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34
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Abstract
Heterotetrameric adaptor-protein complexes AP-1A and AP-3A mediate protein sorting in post-Golgi vesicular transport. AP-1A and AP-3A have been localized to the trans-Golgi network, indicating a function in protein sorting at this compartment. AP-3A appears to mediate trans-Golgi network-to-lysosome and also endosome-to-lysosome protein sorting. AP-1A is thought to be required for both trans-Golgi network-to-endosome transport and endosome-to-trans-Golgi network transport. However, the recent discovery of a role for monomeric GGA (Golgi localized gamma-ear containing, ARF binding protein) adaptor proteins in trans-Golgi network to endosome protein transport has brought into question the long-discussed trans-Golgi network-to-endosome sorting function of AP-1A. Murine cytomegalovirus gp48 contains an unusual di-leucine-based lysosome sorting signal motif and mediates lysosomal sorting of gp48/major histocompatibility complex class I receptor complexes, preventing exposure of major histocompatibility complex class I at the plasma membrane. We analyzed lysosomal sorting of gp48/major histocompatibility complex class I receptor complexes in cell lines deficient for AP-1A, AP-3A and both, to determine their sorting functions. We find that AP1-A and AP3-A mediate distinct and sequential steps in the lysosomal sorting. Both sorting functions are required to prevent MHC class I exposure at the plasma membrane at steady-state.
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Affiliation(s)
- Uwe Reusch
- Zentrum für Biochemie and Molekulare Zellbiologie, Department of Biochemie II, Universität Göttingen, Heinrich-Düker-Weg 12, D-37073 Göttingen, Germany
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35
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Grommé M, Neefjes J. Antigen degradation or presentation by MHC class I molecules via classical and non-classical pathways. Mol Immunol 2002; 39:181-202. [PMID: 12200050 DOI: 10.1016/s0161-5890(02)00101-3] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Major histocompatibility complex (MHC) class I molecules usually present endogenous peptides at the cell surface. This is the result of a cascade of events involving various dedicated proteins like the peptide transporter associated with antigen processing (TAP) and the ER chaperone tapasin. However, alternative ways for class I peptide loading exist which may be highly relevant in a process called cross-priming. Both pathways are described here in detail. One major difference between these pathways is that the proteases involved in the generation of peptides are different. How proteases and peptidases influence peptide generation and degradation will be discussed. These processes determine the amount of peptides available for TAP translocation and class I binding and ultimately the immune response.
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Affiliation(s)
- Monique Grommé
- Division of Tumor Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
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36
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Mahmutefendić H, Kucić N, Lucin P. Distinct pathways for constitutive endocytosis of fully conformed and non-conformed L(d) molecules. Am J Reprod Immunol 2002; 48:87-95. [PMID: 12389597 DOI: 10.1034/j.1600-0897.2002.01134.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
PROBLEM To characterize the constitutive internalization of major histocompatibility complex (MHC) class I molecules, we have studied the expression of completely conformed (full) and unconformed (empty) L(d) molecules on non-polarized murine P815 cells. METHODS OF STUDY Spontaneous endocytosis of L(d) molecules was induced by cycloheximide, an inhibitor of protein synthesis, and their disappearance from the cell surface was determined by flow cytometry. In order to investigate the mechanism of internalization, a palette of inhibitors of endocytosis and vesicular transport was used. RESULTS Inhibitors of clathrine endocytosis did not influence the internalization of L(d) molecules. Inhibitors of caveolar endocytosis and inhibitors of endolysosomal degradation prevented down-regulation of empty, but not of full L(d) molecules. CONCLUSIONS Empty L(d) molecules are internalized mostly by caveolar endocytosis and full L(d) molecules use a different pathway, neither clathrine-mediated nor caveolar. After internalization, full L(d) molecules are probably degraded and empty L(d) molecules recycle between endosomal compartment and the cell surface before they enter into the degradation compartment.
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Affiliation(s)
- Hana Mahmutefendić
- Department of Physiology and Immunology, Medical Faculty, University of Rijeka, Croatia
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37
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Su RC, Miller RG. Stability of surface H-2K(b), H-2D(b), and peptide-receptive H-2K(b) on splenocytes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:4869-77. [PMID: 11673491 DOI: 10.4049/jimmunol.167.9.4869] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have used flow cytometry to study the stability and peptide-binding capability of MHC class I (MHC-I) on the surface of normal C57BL/6 mouse T lymphoblasts. The MHC-I molecules on each cell are nearly evenly divided into two populations with mean half-life values of approximately 1 and 20 h. Our observations suggest that members of the later contain peptide bound with medium to high affinity. Cell surface MHC-I molecules capable of binding exogenous peptide (thus, "peptide-receptive") belong almost entirely to the less stable population. Before exogenous peptide can bind, MHC-I must undergo a change, probably loss of a very low affinity peptide. For MHC-I-K(b), we found that the maximum rate for binding of exogenous peptide corresponds to a t(1/2) value of 12 min. To maintain the 50:50 steady-state distribution of long- vs short-lived MHC-I molecules on the cell surface, approximately 20 short-lived molecules must be exported to the cell surface for each long-lived molecule.
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Affiliation(s)
- R C Su
- Ontario Cancer Institute, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
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38
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Paulson E, Tran C, Collins K, Früh K. KSHV-K5 inhibits phosphorylation of the major histocompatibility complex class I cytoplasmic tail. Virology 2001; 288:369-78. [PMID: 11601908 DOI: 10.1006/viro.2001.1086] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The carboxy-terminal region of major histocompatibility complex class I (MHC I) molecules is required for the rapid internalization mediated by Kaposi's sarcoma-associated herpesvirus (KSHV) proteins K3 and K5. The cytoplasmic tail of MHC I contains highly conserved serine phosphorylation sites that have been implicated in intracellular trafficking. Indeed, in vivo labeling experiments reveal a lack of MHC I phosphorylation in K5-transfected HeLa cells. Phosphorylation of the MHC I tail was restored upon mutation of the PHD/LAP domain of K5. However, deletion and mutation studies of the MHC I tail show that both K3 and K5 are able to downregulate MHC I lacking the conserved phosphorylation site. This result suggests that inhibition of phosphorylation reflects, but does not cause, MHC I internalization. Interestingly, K3 and K5 differ from each other, as well as from human immunodeficiency virus nef, with respect to the minimal MHC I tail sequences required for MHC downregulation. These data support the notion that K3 and K5 downregulate MHC I molecules by a distinct molecular mechanism that is different from other viral immune evasion molecules.
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Affiliation(s)
- E Paulson
- The R. W. Johnson Pharmaceutical Research Institute, 3210 Merryfield Row, San Diego, California 92121, USA
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39
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Park B, Lee S, Kim E, Chang S, Jin M, Ahn K. The truncated cytoplasmic tail of HLA-G serves a quality-control function in post-ER compartments. Immunity 2001; 15:213-24. [PMID: 11520457 DOI: 10.1016/s1074-7613(01)00179-0] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In contrast to the current model of MHC class I trafficking, which predicts that once a MHC class I molecule leaves the ER, it moves to the cell surface by bulk flow, we show that HLA-G that is loaded with suboptimal peptides is retrieved from post-ER compartments to the ER. Loading of HLA-G with high-affinity peptides abrogates this retrieval due to the lack of binding affinity to coatomer. Moreover, the loss of the endocytosis motif in the truncated cytoplasmic tail results in the prolonged half-life of HLA-G on the cell surface. Our findings reveal that surface expression of HLA-G can be further regulated in post-ER compartments and that the truncated cytoplasmic tail plays a critical role in such quality-control mechanisms.
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Affiliation(s)
- B Park
- Graduate School of Biotechnology, Korea University, Seoul 136-701, South Korea
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40
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Kleijmeer MJ, Escola JM, UytdeHaag FG, Jakobson E, Griffith JM, Osterhaus AD, Stoorvogel W, Melief CJ, Rabouille C, Geuze HJ. Antigen loading of MHC class I molecules in the endocytic tract. Traffic 2001; 2:124-37. [PMID: 11247303 DOI: 10.1034/j.1600-0854.2001.020207.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Major histocompatibility complex (MHC) class I molecules bind antigenic peptides that are translocated from the cytosol into the endoplasmic reticulum by the transporter associated with antigen processing. MHC class I loading independent of this transporter also exists and involves peptides derived from exogenously acquired antigens. Thus far, a detailed characterization of the intracellular compartments involved in this pathway is lacking. In the present study, we have used the model system in which peptides derived from measles virus protein F are presented to cytotoxic T cells by B-lymphoblastoid cells that lack the peptide transporter. Inhibition of T cell activation by the lysosomotropic drug ammoniumchloride indicated that endocytic compartments were involved in the class I presentation of this antigen. Using immunoelectron microscopy, we demonstrate that class I molecules and virus protein F co-localized in multivesicular endosomes and lysosomes. Surprisingly, these compartments expressed high levels of class II molecules, and further characterization identified them as MHC class II compartments. In addition, we show that class I molecules co-localized with class II molecules on purified exosomes, the internal vesicles of multivesicular endosomes that are secreted upon fusion of these endosomes with the plasma membrane. Finally, dendritic cells, crucial for the induction of primary immune responses, also displayed class I in endosomes and on exosomes.
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Affiliation(s)
- M J Kleijmeer
- Department of Cell Biology, Institute of Biomembranes, UMC, Utrecht, The Netherlands.
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41
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Abstract
CD1 is an Ag-presenting molecule that can present lipids and glycolipids to T cells. The CD1 genes were first identified in the human, and since then, homologs have been identified in every mammalian species examined to date. Over a decade ago, CD1B and CD1D homologs were identified in the rabbit. We have extended this earlier study by identifying additional CD1 genes with the goal of developing the rabbit as an animal model to study the function of CD1 proteins. We constructed a thymocyte cDNA library and screened the library with CD1-specific probes. Based on nucleotide sequence analyses of the CD1(+) cDNA clones obtained from the library, we have identified two CD1A genes and one CD1E gene as well as determined the complete sequence of the previously identified CD1B gene. The CD1E(+) cDNA clones lacked the transmembrane and cytoplasmic domains and, if translated, would encode for a soluble or secreted CD1E protein. In addition, expression studies demonstrated that the CD1 genes were expressed in peripheral lymphoid tissues as well as in skin, gut, and lung. Of interest is the finding that CD1A2, CD1B, and CD1E genes were found to be expressed by rabbit B cell populations. The rabbit, with a complex CD1 locus composed of at least two CD1A genes, one CD1B gene, one CD1D gene, and one CD1E gene, is an excellent candidate as an animal model to study CD1 proteins.
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Affiliation(s)
- S M Hayes
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL 60153, USA
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42
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Le Gall S, Buseyne F, Trocha A, Walker BD, Heard JM, Schwartz O. Distinct trafficking pathways mediate Nef-induced and clathrin-dependent major histocompatibility complex class I down-regulation. J Virol 2000; 74:9256-66. [PMID: 10982373 PMCID: PMC102125 DOI: 10.1128/jvi.74.19.9256-9266.2000] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human immunodeficiency virus type 1 Nef protein alters the post-Golgi stages of major histocompatibility complex class I (MHC-I) biogenesis. Presumed mechanisms involve the disclosure of a cryptic tyrosine-based sorting signal (YSQA) located in the cytoplasmic tail of HLA-A and -B heavy chains. We changed this signal for a prototypic sorting motif (YSQI or YSQL). Modified HLA-A2 molecules, termed A2-endo, displayed constitutively low surface levels and accumulated in a region close to or within the Golgi apparatus, a behavior reminiscent of wild-type HLA-A2 in Nef-expressing cells. However, several lines of evidence indicate that the action of prototypic signals on MHC-I trafficking differs from that of Nef. Internalization of surface A2-endo was more rapid and was associated with efficient recycling to the surface. A transdominant-negative mutant of dynamin-1 inhibited A2-endo constitutive internalization and Nef-induced CD4 down-regulation, whereas it did not affect the activity of Nef on MHC-I. Moreover, trafficking of A2-endo was still affected by the viral protein, indicating additive effects of prototypic signals and Nef. Therefore, distinct trafficking pathways regulate clathrin-dependent and Nef-induced MHC-I modulation.
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Affiliation(s)
- S Le Gall
- Unité Rétrovirus et Transfert Génétique, URA CNRS 1930, France
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43
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Reimann J, Schirmbeck R. Alternative pathways for processing exogenous and endogenous antigens that can generate peptides for MHC class I-restricted presentation. Immunol Rev 1999; 172:131-52. [PMID: 10631943 DOI: 10.1111/j.1600-065x.1999.tb01362.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The concept of distinct endogenous and exogenous pathways for generating peptides for MHC-I and MHC-II-restricted presentation to CD4+ or CD8+ T cells fits well with the bulk of experimental data. Nevertheless, evidence is emerging for alternative processing pathways that generate peptides for MHC-I-restricted presentation. Using a well characterized, particulate viral antigen of prominent medical importance (the hepatitis B surface antigen), we summarize our evidence that the efficient, endolysosomal processing of exogenous antigens can lead to peptide-loaded MHC-I molecules. In addition, we describe evidence for endolysosomal processing of mutant, stress protein-bound, endogenous antigens that liberate peptides binding to (and presented by) MHC-I molecules. The putative biological role of alternative processing of antigens generating cytotoxic T-lymphocyte-stimulating epitopes is discussed.
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Affiliation(s)
- J Reimann
- Department of Medical Microbiology and Immunology, University of Ulm, Germany.
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44
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Chiu I, Davis DM, Strominger JL. Trafficking of spontaneously endocytosed MHC proteins. Proc Natl Acad Sci U S A 1999; 96:13944-9. [PMID: 10570178 PMCID: PMC24170 DOI: 10.1073/pnas.96.24.13944] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Class I MHC protein primarily presents endogenous antigen but also may present exogenous antigen. Here, we investigated the intracellular pathway of spontaneously internalized class I MHC protein by confocal microscopy. beta(2)-microglobulin (beta(2)m), labeled with a single fluorophore, was exchanged at the surface of B cell transfectants to specifically mark cell surface and endocytosed class I MHC protein. Intracellular beta(2)m colocalized with fluorophore-conjugated transferrin, implying that class I MHC protein endocytosed into early endosomes. These endosomes containing fluorescent beta(2)m were found close to or within the Golgi apparatus, marked by fluorescent ceramide. Even after 24 hr of incubation, very little fluorescent beta(2)m was found in intracellular organelles stained by DiOC(6), marking the endoplasmic reticulum, or fluorophore-conjugated low density lipoprotein, marking late endosomes and lysosomes. Fluorophore-conjugated superantigens (staphylococcal enterotoxin A and B), presumed to enter cells bound to class II MHC protein, also were found to endocytose into beta(2)m-containing early endosomes. Staining with mAb and use of transfectants expressing MHC protein attached to green fluorescent protein confirmed the presence of intracellular compartments rich in both class I and II MHC protein and demonstrated that class I and II MHC protein also colocalize in discrete microdomains at the cell surface. These cell surface microdomains also contained transferrin receptor and often were juxtaposed to cholesterol-rich lipid rafts. Thus, class I and II MHC protein meet in microdomains of the plasma membrane and endocytose into early endosomes, where both may acquire and present exogenous antigen.
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Affiliation(s)
- I Chiu
- Department of Molecular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138, USA
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Story CM, Furman MH, Ploegh HL. The cytosolic tail of class I MHC heavy chain is required for its dislocation by the human cytomegalovirus US2 and US11 gene products. Proc Natl Acad Sci U S A 1999; 96:8516-21. [PMID: 10411907 PMCID: PMC17548 DOI: 10.1073/pnas.96.15.8516] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The US2 and US11 glycoproteins of human cytomegalovirus facilitate destruction of MHC class I heavy chains by proteasomal proteolysis through acceleration of endoplasmic reticulum-to-cytosol dislocation. Modification of the class I heavy chain was used to probe the structural requirements for this sequence of reactions. The cytosolic domain of the class I heavy chain is required for dislocation to the cytosol and for its subsequent destruction. However, interactions between US2 or US11 and the heavy chain are maintained in the absence of the class I cytosolic domain, as shown by chemical crosslinking in vivo and coprecipitation when translated in vitro. Thus, substrate recognition and accelerated destruction of the heavy chain, as facilitated by US2 or US11, are separable events.
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Affiliation(s)
- C M Story
- Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
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Wang Z, Marincola FM, Rivoltini L, Parmiani G, Ferrone S. Selective histocompatibility leukocyte antigen (HLA)-A2 loss caused by aberrant pre-mRNA splicing in 624MEL28 melanoma cells. J Exp Med 1999; 190:205-15. [PMID: 10432284 PMCID: PMC2195569 DOI: 10.1084/jem.190.2.205] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/1999] [Accepted: 05/17/1999] [Indexed: 11/12/2022] Open
Abstract
Histocompatibility leukocyte antigen (HLA)-A2 is used as a restricting element to present several melanoma-associated antigen (MAA)-derived peptides to cytotoxic T lymphocytes (CTLs). HLA-A2 antigen is selectively lost in primary melanoma lesions and more frequently in metastases. Only scanty information is available about the molecular mechanisms underlying this abnormality, in spite of its potentially negative impact on the clinical course of the disease and on the outcome of T cell-based immunotherapy. Therefore, in this study we have shown that the selective HLA-A2 antigen loss in melanoma cells 624MEL28 is caused by a splicing defect of HLA-A2 pre-mRNA because of a base substitution at the 5' splice donor site of intron 2 of the HLA-A2 gene. As a result, HLA-A2 transcripts are spliced to two aberrant forms, one with exon 2 skipping and the other with intron 2 retention. The latter is not translated because of an early premature stop codon in the retained intron. In contrast, the transcript with exon 2 skipping is translated to a truncated HLA-A2 heavy chain without the alpha(1) domain. Such a polypeptide is synthesized in vitro but is not detectable in cells, probably because of the low steady state level of the corresponding mRNA and the low translation efficiency. These results indicate that a single mutational event in an HLA class I gene is sufficient for loss of the corresponding allele. This may account, at least in part, for the high frequency of selective HLA class I allele loss in melanoma cells. Our conclusion emphasizes the need to implement active specific immunotherapy with a combination of peptides presented by various HLA class I alleles. This strategy may counteract the ability of melanoma cells with selective HLA class I allele loss to escape from immune recognition.
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Affiliation(s)
- Zhigang Wang
- From the Department of Immunology, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - Francesco M. Marincola
- Surgery Branch, Division of Clinical Sciences, National Cancer Institute, and the HLA Laboratory, Department of Transfusion Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland 20892
| | - Licia Rivoltini
- Division of Experimental Oncology D, Istituto Nazionale dei Tumori, 20133 Milan, Italy
| | - Giorgio Parmiani
- Division of Experimental Oncology D, Istituto Nazionale dei Tumori, 20133 Milan, Italy
| | - Soldano Ferrone
- From the Department of Immunology, Roswell Park Cancer Institute, Buffalo, New York 14263
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Chun T, Wang K, Zuckermann FA, Gaskins HR. Molecular Cloning and Characterization of a Novel CD1 Gene from the Pig. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.11.6562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Much effort is underway to define the immunological functions of the CD1 multigene family, which encodes a separate lineage of Ag presentation molecules capable of presenting lipid and glycolipid Ags. To identify porcine CD1 homologues, a cosmid library was constructed and screened with a degenerate CD1 α3 domain probe. One porcine CD1 gene (pCD1.1) was isolated and fully characterized. The pCD1.1 gene is organized similarly to MHC class I and other CD1 genes and contains an open reading frame of 1020 bp encoding 339 amino acids. Expression of pCD1.1 mRNA was observed in CD3− thymocytes, B lymphocytes, and tissue macrophages and dendritic cells. The pCD1.1 cDNA was transfected into Chinese hamster ovary cells, and subsequent FACS analysis demonstrated that mAb 76-7-4, previously suggested to be a pig CD1 mAb, recognizes cell surface pCD1.1. Structurally, the pCD1.1 α1 and α2 domains are relatively dissimilar to those of other CD1 molecules, whereas the α3 domain is conserved. Overall, pCD1.1 bears the highest similarity with human CD1a, and the ectodomain sequences characteristically encode a hydrophobic Ag-binding pocket. Distinct from other CD1 molecules, pCD1.1 contains a putative serine phosphorylation motif similar to that found in human, pig, and mouse MHC class Ia molecules and to that found in rodent, but not human, MHC class-I related (MR1) cytoplasmic tail sequences. Thus, pCD1.1 encodes a molecule with a conventional CD1 ectodomain and an MHC class I-like cytoplasmic tail. The unique features of pCD1.1 provoke intriguing questions about the immunologic functions of CD1 and the evolution of Ag presentation gene families.
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Affiliation(s)
| | - Kai Wang
- ‡Department of Molecular Biotechnology, University of Washington, Seattle, WA 98195
| | - Federico A. Zuckermann
- †Veterinary Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801; and
| | - H. Rex Gaskins
- *Animal Sciences and
- †Veterinary Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801; and
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48
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Piguet V, Schwartz O, Le Gall S, Trono D. The downregulation of CD4 and MHC-I by primate lentiviruses: a paradigm for the modulation of cell surface receptors. Immunol Rev 1999; 168:51-63. [PMID: 10399064 DOI: 10.1111/j.1600-065x.1999.tb01282.x] [Citation(s) in RCA: 157] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The human and simian immunodeficiency viruses (HIV and SIV) downregulate the cell surface expression of CD4, their primary receptor, and of class I histocompatibility complex (MHC-I), a critical mediator of immune recognition. While the first of these effects seems important to preserve viral infectivity, the second likely promotes immune evasion. Three HIV-1 proteins, Nef, Env and Vpu, contribute to downregulate CD4, Env forms a complex with CD4 in the endoplasmic reticulum, thereby retaining the receptor in this compartment. Nef and Vpu, on the other hand, act as connectors between CD4 and specific intracellular trafficking pathways, targeting the receptor for degradation in the lysosome and the proteasome, respectively. Some of the downstream partners of the viral proteins in these events have been identified, and include the adaptor complex of clathrin-coated pits, the beta subunit of COP-I coatomer, and the ubiquitin pathway-related h-beta TrCP protein. HIV-induced MHC-I downregulation, mostly the effect of Nef, also reflects a redistribution of this receptor, with its accumulation in the Golgi. The modalities of this process, however, are as yet imperfectly understood. New evidence indicates that the mechanisms employed by primate lentiviruses to downmodulate CD4 and MHC-I are also exploited by a number of cellular regulatory processes.
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Affiliation(s)
- V Piguet
- Department of Genetics and Microbiology, University of Geneva, Switzerland
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Reusch U, Muranyi W, Lucin P, Burgert HG, Hengel H, Koszinowski UH. A cytomegalovirus glycoprotein re-routes MHC class I complexes to lysosomes for degradation. EMBO J 1999; 18:1081-91. [PMID: 10022849 PMCID: PMC1171199 DOI: 10.1093/emboj/18.4.1081] [Citation(s) in RCA: 196] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mouse cytomegalovirus (MCMV) early gene expression interferes with the major histocompatibility complex class I (MHC class I) pathway of antigen presentation. Here we identify a 48 kDa type I transmembrane glycoprotein encoded by the MCMV early gene m06, which tightly binds to properly folded beta2-microglobulin (beta2m)-associated MHC class I molecules in the endoplasmic reticulum (ER). This association is mediated by the lumenal/transmembrane part of the protein. gp48-MHC class I complexes are transported out of the ER, pass the Golgi, but instead of being expressed on the cell surface, they are redirected to the endocytic route and rapidly degraded in a Lamp-1(+) compartment. As a result, m06-expressing cells are impaired in presenting antigenic peptides to CD8(+) T cells. The cytoplasmic tail of gp48 contains two di-leucine motifs. Mutation of the membrane-proximal di-leucine motif of gp48 restored surface expression of MHC class I, while mutation of the distal one had no effect. The results establish a novel viral mechanism for downregulation of MHC class I molecules by directly binding surface-destined MHC complexes and exploiting the cellular di-leucine sorting machinery for lysosomal degradation.
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Affiliation(s)
- U Reusch
- Max von Pettenkofer-Institut and Genzentrum, Ludwig-Maximilians-Universität München, 81377 München
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Abstract
In view of the recently published data, the HLA-G class Ib gene appears to be a functional locus. This is based on the following observations: 1) HLA-G is capable of presenting nonamer peptides and of exerting antigen-presenting functions; 2) HLA-G is a ligand for at least three natural killer (NK) and other cell inhibitory receptors of the immunoglobulin superfamily, namely leukocyte immunoglobulin-like receptor-1/immunoglobulin-like transcript (ILT)-2, ILT-4 and p49; 3) in addition to the extravillous cytotrophoblast cells, HLA-G proteins have been detected in endothelial cells of placental chorionic villi, as well as in amniotic fluid and in some medullary thymic epithelial cells; 4) major histocompatibility complex (MHC) class Ib genes that share the unique characteristics of HLA-G, including a high expression in placenta, have been reported in other mammalian species. In addition to the classical MHC class I roles (antigen presentation and ligation to NK receptors inducing inhibitory and/or activatory signals), HLA-G is likely to exert other, novel functions: first, HLA-G was shown to be involved in the control of HLA-E expression by furnishing the appropriate class I leader sequence nonamer peptide; second, we hypothesize that HLA-G could be a regulator of placental angiogenesis; third, soluble HLA-G isoforms may act as specific immunosuppressors during pregnancy. Such functional properties, although incompletely understood, are likely to be important in the outcome of human pregnancies but also in normal adult life.
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