1
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Czaja AJ. Introducing Molecular Chaperones into the Causality and Prospective Management of Autoimmune Hepatitis. Dig Dis Sci 2023; 68:4098-4116. [PMID: 37755606 PMCID: PMC10570239 DOI: 10.1007/s10620-023-08118-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Accepted: 09/18/2023] [Indexed: 09/28/2023]
Abstract
Molecular chaperones influence the immunogenicity of peptides and the activation of effector T cells, and their pathogenic roles in autoimmune hepatitis are unclear. Heat shock proteins are pivotal in the processing and presentation of peptides that activate CD8+ T cells. They can also induce regulatory B and T cells and promote immune tolerance. Tapasin and the transporter associated with antigen processing-binding protein influence the editing and loading of high-affinity peptides for presentation by class I molecules of the major histocompatibility complex. Their over-expression could enhance the autoimmune response, and their deficiency could weaken it. The lysosome-associated membrane protein-2a isoform in conjunction with heat shock cognate 70 supports the importation of cytosolic proteins into lysosomes. Chaperone-mediated autophagy can then process the peptides for activation of CD4+ T cells. Over-expression of autophagy in T cells may also eliminate negative regulators of their activity. The human leukocyte antigen B-associated transcript three facilitates the expression of class II peptide receptors, inhibits T cell apoptosis, prevents T cell exhaustion, and sustains the immune response. Immunization with heat shock proteins has induced immune tolerance in experimental models and humans with autoimmune disease by inducing regulatory T cells. Therapeutic manipulation of other molecular chaperones may promote T cell exhaustion and induce tolerogenic dendritic cells. In conclusion, molecular chaperones constitute an under-evaluated family of ancillary proteins that could affect the occurrence, severity, and outcome of autoimmune hepatitis. Clarification of their contributions to the immune mechanisms and clinical activity of autoimmune hepatitis could have therapeutic implications.
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Affiliation(s)
- Albert J Czaja
- Mayo Clinic College of Medicine and Science, 200 First Street S.W., Rochester, MN, 55905, USA.
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2
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Lan BH, Becker M, Freund C. The mode of action of tapasin on major histocompatibility class I (MHC-I) molecules. J Biol Chem 2023; 299:102987. [PMID: 36758805 PMCID: PMC10040737 DOI: 10.1016/j.jbc.2023.102987] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 01/05/2023] [Accepted: 01/31/2023] [Indexed: 02/10/2023] Open
Abstract
Tapasin (Tsn) plays a critical role in antigen processing and presentation by major histocompatibility complex class I (MHC-I) molecules. The mechanism of Tsn-mediated peptide loading and exchange hinges on the conformational dynamics governing the interaction of Tsn and MHC-I with recent structural and functional studies pinpointing the critical sites of direct or allosteric regulation. In this review, we highlight these recent findings and relate them to the extensive molecular and cellular data that are available for these evolutionary interdependent proteins. Furthermore, allotypic differences of MHC-I with regard to the editing and chaperoning function of Tsn are reviewed and related to the mechanistic observations. Finally, evolutionary aspects of the mode of action of Tsn will be discussed, a short comparison with the Tsn-related molecule TAPBPR (Tsn-related protein) will be given, and the impact of Tsn on noncanonical MHC-I molecules will be described.
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Affiliation(s)
- By Huan Lan
- Institute of Chemistry & Biochemistry, Laboratory of Protein Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Moritz Becker
- Institute of Chemistry & Biochemistry, Laboratory of Protein Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Christian Freund
- Institute of Chemistry & Biochemistry, Laboratory of Protein Biochemistry, Freie Universität Berlin, Berlin, Germany.
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3
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Kwok D, Okada H. T-Cell based therapies for overcoming neuroanatomical and immunosuppressive challenges within the glioma microenvironment. J Neurooncol 2020; 147:281-295. [PMID: 32185647 PMCID: PMC7182069 DOI: 10.1007/s11060-020-03450-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 03/05/2020] [Indexed: 12/22/2022]
Abstract
Glioblastoma remains as the most common and aggressive primary adult brain tumor to date. Within the last decade, cancer immunotherapy surfaced as a broadly successful therapeutic approach for a variety of cancers. However, due to the neuroanatomical and immunosuppressive nature of malignant gliomas, conventional chemotherapy and radiotherapy treatments garner limited efficacy in patients with these tumors. The intricate structure of the blood brain barrier restricts immune accessibility into the tumor microenvironment, and malignant gliomas can activate various adaptive responses to subvert anticancer immune responses and reinstate an immunosuppressive milieu. Yet, evidence of lymphocyte infiltration within the brain and recent advancements made in cell engineering technologies implicate the vast potential in the future of neuro-oncological immunotherapy. Previous immunotherapy platforms have paved way to improved modalities, which includes but is not limited to personalized vaccines and chimeric antigen receptor T-cell therapy. This review will cover the various neuroanatomical and immunosuppressive features of central nervous system tumors and highlight the innovations made in T-cell based therapies to overcome the challenges presented by the glioblastoma microenvironment.
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Affiliation(s)
- Darwin Kwok
- Department of Neurological Surgery, University of California, San Francisco, Helen Diller Family Cancer Research Building HD 472 1450 3rd Street, San Francisco, CA, 94158-0520, USA
| | - Hideho Okada
- Department of Neurological Surgery, University of California, San Francisco, Helen Diller Family Cancer Research Building HD 472 1450 3rd Street, San Francisco, CA, 94158-0520, USA.
- The Parker Institute for Cancer Immunotherapy, San Francisco, CA, USA.
- Cancer Immunotherapy Program, University of California, San Francisco, CA, USA.
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4
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Natarajan K, Jiang J, Margulies DH. Structural aspects of chaperone-mediated peptide loading in the MHC-I antigen presentation pathway. Crit Rev Biochem Mol Biol 2019; 54:164-173. [PMID: 31084439 DOI: 10.1080/10409238.2019.1610352] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Recognition of foreign and dysregulated antigens by the cellular innate and adaptive immune systems is in large part dependent on the cell surface display of peptide/MHC (pMHC) complexes. The formation of such complexes requires the generation of antigenic peptides, proper folding of MHC molecules, loading of peptides onto MHC molecules, glycosylation, and transport to the plasma membrane. This complex series of biosynthetic, biochemical, and cell biological reactions is known as "antigen processing and presentation". Here, we summarize recent work, focused on the structural and functional characterization of the key MHC-I-dedicated chaperones, tapasin, and TAPBPR. The mechanisms reflect the ability of conformationally flexible molecules to adapt to their ligands, and are comparable to similar processes that are exploited in peptide antigen loading in the MHC-II pathway.
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Affiliation(s)
- Kannan Natarajan
- a Molecular Biology Section, Laboratory of Immune System Biology , National Institute of Allergy and Infectious Diseases, National Institutes of Health , Bethesda , MD , USA
| | - Jiansheng Jiang
- a Molecular Biology Section, Laboratory of Immune System Biology , National Institute of Allergy and Infectious Diseases, National Institutes of Health , Bethesda , MD , USA
| | - David H Margulies
- a Molecular Biology Section, Laboratory of Immune System Biology , National Institute of Allergy and Infectious Diseases, National Institutes of Health , Bethesda , MD , USA
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5
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Chuntova P, Downey KM, Hegde B, Almeida ND, Okada H. Genetically Engineered T-Cells for Malignant Glioma: Overcoming the Barriers to Effective Immunotherapy. Front Immunol 2019; 9:3062. [PMID: 30740109 PMCID: PMC6357938 DOI: 10.3389/fimmu.2018.03062] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 12/11/2018] [Indexed: 12/12/2022] Open
Abstract
Malignant gliomas carry a dismal prognosis. Conventional treatment using chemo- and radiotherapy has limited efficacy with adverse events. Therapy with genetically engineered T-cells, such as chimeric antigen receptor (CAR) T-cells, may represent a promising approach to improve patient outcomes owing to their potential ability to attack highly infiltrative tumors in a tumor-specific manner and possible persistence of the adaptive immune response. However, the unique anatomical features of the brain and susceptibility of this organ to irreversible tissue damage have made immunotherapy especially challenging in the setting of glioma. With safety concerns in mind, multiple teams have initiated clinical trials using CAR T-cells in glioma patients. The valuable lessons learnt from those trials highlight critical areas for further improvement: tackling the issues of the antigen presentation and T-cell homing in the brain, immunosuppression in the glioma microenvironment, antigen heterogeneity and off-tumor toxicity, and the adaptation of existing clinical therapies to reflect the intricacies of immune response in the brain. This review summarizes the up-to-date clinical outcomes of CAR T-cell clinical trials in glioma patients and examines the most pressing hurdles limiting the efficacy of these therapies. Furthermore, this review uses these hurdles as a framework upon which to evaluate cutting-edge pre-clinical strategies aiming to overcome those barriers.
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Affiliation(s)
- Pavlina Chuntova
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Kira M Downey
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Bindu Hegde
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Neil D Almeida
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States.,George Washington University School of Medicine and Health Sciences, Washington, DC, United States
| | - Hideho Okada
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States.,The Parker Institute for Cancer Immunotherapy, University of California, San Francisco, San Francisco, CA, United States.,Cancer Immunotherapy Program, University of California, San Francisco, San Francisco, CA, United States
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6
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Shionoya Y, Kanaseki T, Miyamoto S, Tokita S, Hongo A, Kikuchi Y, Kochin V, Watanabe K, Horibe R, Saijo H, Tsukahara T, Hirohashi Y, Takahashi H, Sato N, Torigoe T. Loss of tapasin in human lung and colon cancer cells and escape from tumor-associated antigen-specific CTL recognition. Oncoimmunology 2017; 6:e1274476. [PMID: 28344889 DOI: 10.1080/2162402x.2016.1274476] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 11/30/2016] [Accepted: 12/15/2016] [Indexed: 01/05/2023] Open
Abstract
Cytotoxic T-lymphocytes (CTLs) lyse target cells after recognizing the complexes of peptides and MHC class I molecules (pMHC I) on cell surfaces. Tapasin is an essential component of the peptide-loading complex (PLC) and its absence influences the surface repertoire of MHC class I peptides. In the present study, we assessed tapasin expression in 85 primary tumor lesions of non-small cell lung cancer (NSCLC) patients, demonstrating that tapasin expression positively correlated with patient survival. CD8+ T-cell infiltration of tumor lesions was synergistically observed with tapasin expression and correlated positively with survival. To establish a direct link between loss of tapasin and CTL recognition in human cancer models, we targeted the tapasin gene by CRISPR/Cas9 system and generated tapasin-deficient variants of human lung as well as colon cancer cells. We induced the CTLs recognizing endogenous tumor-associated antigens (TAA), survivin or cep55, and they responded to each tapasin-proficient wild type. In contrast, both CTL lines ignored the tapasin-deficient variants despite their antigen expression. Moreover, the adoptive transfer of the cep55-specific CTL line failed to prevent tumor growth in mice bearing the tapasin-deficient variant. Loss of tapasin most likely limited antigen processing of TAAs and led to escape from TAA-specific CTL recognition. Tapasin expression is thus a key for CTL surveillance against human cancers.
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Affiliation(s)
- Yosuke Shionoya
- Department of Pathology, Sapporo Medical University, Sapporo, Japan; Department of Respiratory Medicine and Allergology, Sapporo Medical University, Sapporo, Japan
| | - Takayuki Kanaseki
- Department of Pathology, Sapporo Medical University , Sapporo, Japan
| | - Sho Miyamoto
- Department of Pathology, Sapporo Medical University , Sapporo, Japan
| | - Serina Tokita
- Department of Pathology, Sapporo Medical University , Sapporo, Japan
| | - Ayumi Hongo
- Department of Pathology, Sapporo Medical University , Sapporo, Japan
| | - Yasuhiro Kikuchi
- Department of Pathology, Sapporo Medical University , Sapporo, Japan
| | - Vitaly Kochin
- Department of Pathology, Sapporo Medical University , Sapporo, Japan
| | - Kazue Watanabe
- Department of Pathology, Sapporo Medical University, Sapporo, Japan; Research and Development Division, Medical and Biological Laboratories Company, Limited, Ina, Japan
| | - Ryota Horibe
- Department of Pathology, Sapporo Medical University, Sapporo, Japan; Department of Respiratory Medicine and Allergology, Sapporo Medical University, Sapporo, Japan
| | - Hiroshi Saijo
- Department of Pathology, Sapporo Medical University, Sapporo, Japan; Department of Respiratory Medicine and Allergology, Sapporo Medical University, Sapporo, Japan
| | | | | | - Hiroki Takahashi
- Department of Respiratory Medicine and Allergology, Sapporo Medical University , Sapporo, Japan
| | - Noriyuki Sato
- Department of Pathology, Sapporo Medical University , Sapporo, Japan
| | - Toshihiko Torigoe
- Department of Pathology, Sapporo Medical University , Sapporo, Japan
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7
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Hermann C, van Hateren A, Trautwein N, Neerincx A, Duriez PJ, Stevanović S, Trowsdale J, Deane JE, Elliott T, Boyle LH. TAPBPR alters MHC class I peptide presentation by functioning as a peptide exchange catalyst. eLife 2015; 4:e09617. [PMID: 26439010 PMCID: PMC4718805 DOI: 10.7554/elife.09617] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 10/05/2015] [Indexed: 12/29/2022] Open
Abstract
Our understanding of the antigen presentation pathway has recently been enhanced with the identification that the tapasin-related protein TAPBPR is a second major histocompatibility complex (MHC) class I-specific chaperone. We sought to determine whether, like tapasin, TAPBPR can also influence MHC class I peptide selection by functioning as a peptide exchange catalyst. We show that TAPBPR can catalyse the dissociation of peptides from peptide-MHC I complexes, enhance the loading of peptide-receptive MHC I molecules, and discriminate between peptides based on affinity in vitro. In cells, the depletion of TAPBPR increased the diversity of peptides presented on MHC I molecules, suggesting that TAPBPR is involved in restricting peptide presentation. Our results suggest TAPBPR binds to MHC I in a peptide-receptive state and, like tapasin, works to enhance peptide optimisation. It is now clear there are two MHC class I specific peptide editors, tapasin and TAPBPR, intimately involved in controlling peptide presentation to the immune system.
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Affiliation(s)
- Clemens Hermann
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Andy van Hateren
- Faculty of Medicine and Institute for Life Science, University of Southampton, Southampton, United Kingdom
| | - Nico Trautwein
- Department of Immunology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Andreas Neerincx
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Patrick J Duriez
- Cancer Research UK Protein Core Facility, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Stefan Stevanović
- Department of Immunology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - John Trowsdale
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Janet E Deane
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Tim Elliott
- Faculty of Medicine and Institute for Life Science, University of Southampton, Southampton, United Kingdom
| | - Louise H Boyle
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
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8
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Thuring C, Follin E, Geironson L, Freyhult E, Junghans V, Harndahl M, Buus S, Paulsson KM. HLA class I is most tightly linked to levels of tapasin compared with other antigen-processing proteins in glioblastoma. Br J Cancer 2015; 113:952-62. [PMID: 26313662 PMCID: PMC4578088 DOI: 10.1038/bjc.2015.297] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 07/15/2014] [Accepted: 07/25/2015] [Indexed: 12/24/2022] Open
Abstract
Background: Tumour cells can evade the immune system by dysregulation of human leukocyte antigens (HLA-I). Low quantity and/or altered quality of HLA-I cell surface expression is the result of either HLA-I alterations or dysregulations of proteins of the antigen-processing machinery (APM). Tapasin is an APM protein dedicated to the maturation of HLA-I and dysregulation of tapasin has been linked to higher malignancy in several different tumours. Methods: We studied the expression of APM components and HLA-I, as well as HLA-I tapasin-dependency profiles in glioblastoma tissues and corresponding cell lines. Results: Tapasin displayed the strongest correlation to HLA-I heavy chain but also clustered with β2-microglobulin, transporter associated with antigen processing (TAP) and LMP. Moreover, tapasin also correlated to survival of glioblastoma patients. Some APM components, for example, TAP1/TAP2 and LMP2/LMP7, showed variable but coordinated expression, whereas ERAP1/ERAP2 displayed an imbalanced expression pattern. Furthermore, analysis of HLA-I profiles revealed variable tapasin dependence of HLA-I allomorphs in glioblastoma patients. Conclusions: Expression of APM proteins is highly variable between glioblastomas. Tapasin stands out as the APM component strongest correlated to HLA-I expression and we proved that HLA-I profiles in glioblastoma patients include tapasin-dependent allomorphs. The level of tapasin was also correlated with patient survival time. Our results support the need for individualisation of immunotherapy protocols.
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Affiliation(s)
- Camilla Thuring
- Immunology Section, Department of Experimental Medical Science, Lund University, SE-221 84 Lund, Sweden
| | - Elna Follin
- Immunology Section, Department of Experimental Medical Science, Lund University, SE-221 84 Lund, Sweden
| | - Linda Geironson
- Immunology Section, Department of Experimental Medical Science, Lund University, SE-221 84 Lund, Sweden
| | - Eva Freyhult
- Science for Life Laboratory, Bioinformatics Infrastructure for Life Sciences, Department of Medical Sciences, Cancer Pharmacology and Computational Medicine, Uppsala University, SE-751 05 Uppsala, Sweden
| | - Victoria Junghans
- Immunology Section, Department of Experimental Medical Science, Lund University, SE-221 84 Lund, Sweden
| | - Mikkel Harndahl
- Department of Experimental Immunology, Institute of International Health, Immunology and Microbiology, DK-2200 Copenhagen, Denmark
| | - Søren Buus
- Department of Experimental Immunology, Institute of International Health, Immunology and Microbiology, DK-2200 Copenhagen, Denmark
| | - Kajsa M Paulsson
- Immunology Section, Department of Experimental Medical Science, Lund University, SE-221 84 Lund, Sweden
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9
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Porter KM, Hermann C, Traherne JA, Boyle LH. TAPBPR isoforms exhibit altered association with MHC class I. Immunology 2014; 142:289-99. [PMID: 24444341 PMCID: PMC4008236 DOI: 10.1111/imm.12253] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 01/14/2014] [Accepted: 01/14/2014] [Indexed: 01/14/2023] Open
Abstract
The tapasin-related protein TAPBPR is a novel component of the antigen processing and presentation pathway, which binds to MHC class I coupled with β2-microglobulin. We describe six alternatively spliced TAPBPR transcripts from the TAPBPL gene and investigate three of these at a protein level. TAPBPR transcripts lacking exon 5 result in loss of the membrane proximal IgC domain and loss of ability to bind to MHC class I. Alternative acceptor and donor splice sites in exon 4 of TAPBPR altered the reading frame in the IgV domain and produced a truncated TAPBPR product. An additional exon in the TAPBPL gene was identified that encodes extra residues in the cytoplasmic tail of TAPBPR. This longer TAPBPR protein interacted with MHC class I but was attenuated in its ability to down-regulate surface expression of MHC class I. The abundance of these alternative transcripts in peripheral blood mononuclear cells and dendritic cells suggests an important role of TAPBPR isoforms in vivo.
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Affiliation(s)
- Keith M Porter
- Department of Pathology, Cambridge Institute of Medical Research, University of Cambridge, Wellcome TrustCambridge, UK
| | - Clemens Hermann
- Department of Pathology, Cambridge Institute of Medical Research, University of Cambridge, Wellcome TrustCambridge, UK
| | - James A Traherne
- Department of Pathology, Cambridge Institute of Medical Research, University of Cambridge, Wellcome TrustCambridge, UK
| | - Louise H Boyle
- Department of Pathology, Cambridge Institute of Medical Research, University of Cambridge, Wellcome TrustCambridge, UK
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10
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Hermann C, Strittmatter LM, Deane JE, Boyle LH. The binding of TAPBPR and Tapasin to MHC class I is mutually exclusive. THE JOURNAL OF IMMUNOLOGY 2013; 191:5743-50. [PMID: 24163410 DOI: 10.4049/jimmunol.1300929] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The loading of peptide Ags onto MHC class I molecules is a highly controlled process in which the MHC class I-dedicated chaperone tapasin is a key player. We recently identified a tapasin-related molecule, TAPBPR, as an additional component in the MHC class I Ag-presentation pathway. In this study, we show that the amino acid residues important for tapasin to interact with MHC class I are highly conserved on TAPBPR. We identify specific residues in the N-terminal and C-terminal domains of TAPBPR involved in associating with MHC class I. Furthermore, we demonstrate that residues on MHC class I crucial for its association with tapasin, such as T134, are also essential for its interaction with TAPBPR. Taken together, the data indicate that TAPBPR and tapasin bind in a similar orientation to the same face of MHC class I. In the absence of tapasin, the association of MHC class I with TAPBPR is increased. However, in the absence of TAPBPR, the interaction between MHC class I and tapasin does not increase. In light of our findings, previous data determining the function of tapasin in the MHC class I Ag-processing and presentation pathway must be re-evaluated.
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Affiliation(s)
- Clemens Hermann
- Department of Pathology, Cambridge Institute of Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
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11
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Geironson L, Thuring C, Harndahl M, Rasmussen M, Buus S, Røder G, Paulsson KM. Tapasin facilitation of natural HLA-A and -B allomorphs is strongly influenced by peptide length, depends on stability, and separates closely related allomorphs. THE JOURNAL OF IMMUNOLOGY 2013; 191:3939-47. [PMID: 23980206 DOI: 10.4049/jimmunol.1201741] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Despite an abundance of peptides inside a cell, only a small fraction is ultimately presented by HLA-I on the cell surface. The presented peptides have HLA-I allomorph-specific motifs and are restricted in length. So far, detailed length studies have been limited to few allomorphs. Peptide-HLA-I (pHLA-I) complexes of different allomorphs are qualitatively and quantitatively influenced by tapasin to different degrees, but again, its effect has only been investigated for a small number of HLA-I allomorphs. Although both peptide length and tapasin dependence are known to be important for HLA-I peptide presentation, the relationship between them has never been studied. In this study, we used random peptide libraries from 7- to 13-mers and studied binding in the presence and absence of a recombinant truncated form of tapasin. The data show that HLA-I allomorphs are differentially affected by tapasin, different lengths of peptides generated different amounts of pHLA-I complexes, and HLA-A allomorphs are generally less restricted than HLA-B allomorphs to peptides of the classical length of 8-10 aa. We also demonstrate that tapasin facilitation varies for different peptide lengths, and that the correlation between high degree of tapasin facilitation and low stability is valid for different random peptide mixes of specific lengths. In conclusion, these data show that tapasin has specificity for the combination of peptide length and HLA-I allomorph, and suggest that tapasin promotes formation of pHLA-I complexes with high on and off rates, an important intermediary step in the HLA-I maturation process.
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Affiliation(s)
- Linda Geironson
- Department of Experimental Medical Science, Immunology Section, Lund University, 221 84 Lund, Sweden
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12
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Simone LC, Tuli A, Simone PD, Wang X, Solheim JC. Analysis of major histocompatibility complex class I folding: novel insights into intermediate forms. ACTA ACUST UNITED AC 2012; 79:249-62. [PMID: 22329842 DOI: 10.1111/j.1399-0039.2012.01849.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Folding around a peptide ligand is integral to the antigen presentation function of major histocompatibility complex (MHC) class I molecules. Several lines of evidence indicate that the broadly cross-reactive 34-1-2 antibody is sensitive to folding of the MHC class I peptide-binding groove. Here, we show that peptide-loading complex proteins associated with the murine MHC class I molecule K(d) are found primarily in association with the 34-1-2(+) form. This led us to hypothesize that the 34-1-2 antibody may recognize intermediately, as well as fully, folded MHC class I molecules. To further characterize the form(s) of MHC class I molecules recognized by 34-1-2, we took advantage of its cross-reactivity with L(d) . Recognition of the open and folded forms of L(d) by the 64-3-7 and 30-5-7 antibodies, respectively, has been extensively characterized, providing us with parameters against which to compare 34-1-2 reactivity. We found that the 34-1-2(+) L(d) molecules displayed characteristics indicative of incomplete folding, including increased tapasin association, endoplasmic reticulum retention, and instability at the cell surface. Moreover, we show that an L(d) -specific peptide induced folding of the 34-1-2(+) L(d) intermediate. Altogether, these results yield novel insights into the nature of MHC class I molecules recognized by the 34-1-2 antibody.
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Affiliation(s)
- L C Simone
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198-6805, USA
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13
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Abstract
Peptide binding to MHC class I molecules is a component of a folding and assembly process that occurs in the endoplasmic reticulum (ER) and uses both cellular chaperones and dedicated factors. The involvement of glycoprotein quality-control chaperones and cellular oxidoreductases in peptide binding has led to models that are gradually being refined. Some aspects of the peptide loading process (e.g., the biosynthesis and degradation of MHC class I complexes) conform to models of glycoprotein quality control, but other aspects (e.g., the formation of a stable disulfide-linked dimer between tapasin and ERp57) deviate from models of chaperone and oxidoreductase function. Here we review what is known about the intersection of glycoprotein folding, oxidative reactions, and MHC class I peptide loading, emphasizing events that occur in the ER and within the MHC class I peptide loading complex.
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Affiliation(s)
- David R Peaper
- Howard Hughes Medical Institute, Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
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14
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Everett MW, Edidin M. Tapasin Increases Efficiency of MHC I Assembly in the Endoplasmic Reticulum but Does Not Affect MHC I Stability at the Cell Surface. THE JOURNAL OF IMMUNOLOGY 2007; 179:7646-52. [DOI: 10.4049/jimmunol.179.11.7646] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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15
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Aladin F, Lautscham G, Humphries E, Coulson J, Blake N. Targeting tumour cells with defects in the MHC Class I antigen processing pathway with CD8+ T cells specific for hydrophobic TAP- and Tapasin-independent peptides: the requirement for directed access into the ER. Cancer Immunol Immunother 2007; 56:1143-52. [PMID: 17143611 PMCID: PMC11031051 DOI: 10.1007/s00262-006-0263-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Accepted: 11/16/2006] [Indexed: 10/23/2022]
Abstract
It is becoming increasingly apparent that the majority of tumours display defects in the MHC class I antigen processing pathway, particularly low levels of the transporters-associated with antigen processing (TAP) and tapasin. Thus, immunotherapy approaches targeting such tumours with CD8+ cytotoxic T lymphocytes (CTL) requires strategies to overcome these defects. Previously we had identified an antigen processing pathway by which cytosolically derived hydrophobic peptides could be presented in the absence of TAP. Here we show in the tapasin-negative cell line 721.220 that a number of these hydrophobic TAP-independent peptides can also be presented in a tapasin-independent manner. Yet when these experiments were extended to tumour cell lines derived from small cell lung cancer (SCLC), which we show to be tapasin deficient in addition to TAP-negative, the TAP-, tapasin-independent peptides were not presented. This lack of presentation could be rectified by pre-treatment of SCLC cells with IFNgamma. Alternatively, by directing the TAP-, tapasin-independent peptides into the endoplasmic reticulum (ER) via an ER signal sequence, these peptides were presented efficiently by SCLC cells. We infer from this data that the TAP-independent pathway for presentation of hydrophobic peptides generates a low concentration of peptide in the ER and, for tumour cells which also lack tapasin, this concentration of antigenic peptide is insufficient to load onto MHC class I molecules. Thus, for immunotherapeutic approaches to target SCLC and other tumours with defects in the MHC class I antigen processing pathway it will be important to consider strategies that address tapasin-defects.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 2
- ATP Binding Cassette Transporter, Subfamily B, Member 3
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/physiology
- Antigen Presentation
- Antigens, Viral/immunology
- Antigens, Viral/metabolism
- CD8-Positive T-Lymphocytes/immunology
- Carcinoma, Small Cell/pathology
- Cell Line, Transformed
- Cell Line, Tumor
- Cytosol/metabolism
- Endoplasmic Reticulum/metabolism
- HLA-A Antigens/immunology
- HLA-A2 Antigen/immunology
- HLA-A24 Antigen
- Herpesvirus 4, Human/immunology
- Histocompatibility Antigens Class I/immunology
- Humans
- Hydrophobic and Hydrophilic Interactions
- Immediate-Early Proteins/immunology
- Immediate-Early Proteins/metabolism
- Intracellular Membranes/metabolism
- Lung Neoplasms/pathology
- Membrane Transport Proteins/deficiency
- Membrane Transport Proteins/physiology
- Peptide Fragments/chemistry
- Peptide Fragments/immunology
- Peptide Fragments/metabolism
- Phosphoproteins/immunology
- Phosphoproteins/metabolism
- Protein Sorting Signals/physiology
- Protein Transport
- T-Cell Antigen Receptor Specificity
- Trans-Activators/immunology
- Trans-Activators/metabolism
- Transfection
- Viral Matrix Proteins/immunology
- Viral Matrix Proteins/metabolism
- Viral Proteins/immunology
- Viral Proteins/metabolism
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Affiliation(s)
- Farah Aladin
- Division of Medical Microbiology, University of Liverpool, 8th Floor Duncan Building, Daulby Street, L69 3GA Liverpool, UK
- School of Biomedical Sciences, University of Liverpool, Liverpool, UK
| | - Georg Lautscham
- CRUK Institute for Cancer Studies, University of Birmingham, Birmingham, UK
| | - Elizabeth Humphries
- Division of Medical Microbiology, University of Liverpool, 8th Floor Duncan Building, Daulby Street, L69 3GA Liverpool, UK
| | - Judy Coulson
- School of Biomedical Sciences, University of Liverpool, Liverpool, UK
| | - Neil Blake
- Division of Medical Microbiology, University of Liverpool, 8th Floor Duncan Building, Daulby Street, L69 3GA Liverpool, UK
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16
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Chen M, Bouvier M. Analysis of interactions in a tapasin/class I complex provides a mechanism for peptide selection. EMBO J 2007; 26:1681-90. [PMID: 17332746 PMCID: PMC1829385 DOI: 10.1038/sj.emboj.7601624] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2006] [Accepted: 01/30/2007] [Indexed: 11/08/2022] Open
Abstract
We examined interactions in a soluble tapasin (TPN)/HLA-B*0801 complex to gain mechanistic insights into the functions of TPN. Results show that TPN acts as a chaperone by increasing the ratio of active-to-inactive peptide-deficient HLA-B*0801 molecules in solution. TPN causes peptides to associate and dissociate faster owing to its effect on widening the binding groove of HLA-B*0801 molecules. Our data indicate that a TPN-assisted mechanism of peptide selection relies on disruption of conserved hydrogen bonds at the C-terminal end of the groove. Peptide sequence-dependent interactions along the entire length of the groove also play a role in this mechanism. We suggest that TPN influences presentation of antigenic peptides according to a mechanistically complicated process in which bound candidate peptides that are unable to conformationally disengage TPN from class I molecules are excluded from the repertoire. Overall, these studies unify our understanding of the functions of TPN.
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Affiliation(s)
- Mingnan Chen
- School of Pharmacy, University of Connecticut, Storrs, CT, USA
| | - Marlene Bouvier
- School of Pharmacy, University of Connecticut, Storrs, CT, USA
- School of Pharmacy, University of Connecticut, 69 N Eagleville Road, U-3092, Storrs, CT 06269, USA. Tel.: +1 860 486 4355; Fax: +1 860 486 4998; E-mail:
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17
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Jørgensen SM, Grimholt U, Gjøen T. Cloning and expression analysis of an Atlantic salmon (Salmo salar L.) tapasin gene. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2007; 31:708-19. [PMID: 17157378 DOI: 10.1016/j.dci.2006.10.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Revised: 10/16/2006] [Accepted: 10/16/2006] [Indexed: 05/12/2023]
Abstract
Loading of the major histocompatibility complex (MHC) class I molecule with peptide is mediated by the multimeric peptide-loading complex in the ER where the glycoprotein tapasin (TAPBP) is required for stabilization of the complex and for control of peptide loading onto MHC class I. To expand our knowledge on antigen presentation genes in Atlantic salmon, we isolated a full-length salmon tapasin cDNA sequence (Sasa-TAPBP). It encoded a 443 bp amino acid sequence with two N-glycosylation sites, two conserved mammalian tapasin signature motifs, two Ig superfamily (IgSf) domains, a transmembrane (TM) domain and an ER-retention KK motif at the C-terminal end, indicative of a similar function as mammalian tapasins. We analysed the regulation of Sasa-TAPBP under immunostimulatory conditions and found an mRNA-upregulation during early infectious salmon anemia virus (ISAV) infection and poly I:C stimulation in vivo and in vitro, in line with our previous findings for other MHC class I pathway genes.
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Affiliation(s)
- Sven Martin Jørgensen
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, 0316 Oslo, Norway
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18
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Montserrat V, Galocha B, Marcilla M, Vázquez M, López de Castro JA. HLA-B*2704, an Allotype Associated with Ankylosing Spondylitis, Is Critically Dependent on Transporter Associated with Antigen Processing and Relatively Independent of Tapasin and Immunoproteasome for Maturation, Surface Expression, and T Cell Recognition: Relationship to B*2705 and B*2706. THE JOURNAL OF IMMUNOLOGY 2006; 177:7015-23. [PMID: 17082617 DOI: 10.4049/jimmunol.177.10.7015] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
B*2704 is strongly associated to ankylosing spondylitis in Asian populations. It differs from the main HLA-B27 allotype, B*2705, in three amino acid changes. We analyzed the influence of tapasin, TAP, and immunoproteasome induction on maturation, surface expression, and T cell allorecognition of B*2704 and compared some of these features with B*2705 and B*2706, allotypes not associated to disease. In the tapasin-deficient .220 cell line, this chaperone significantly influenced the extent of folding of B*2704 and B*2705, but not their egress from the endoplasmic reticulum. In contrast, B*2706 showed faster folding and no accumulation in the endoplasmic reticulum in the absence of tapasin. Surface expression of B*2704 was more tapasin dependent than B*2705. However, expression of free H chain decreased in the presence of this chaperone for B*2705 but not B*2704, suggesting that more suboptimal ligands were loaded on B*2705 in the absence of tapasin. Despite its influence on surface expression, tapasin had little effect on allorecognition of B*2704. Both surface expression and T cell recognition of B*2704 were critically dependent on TAP, as established with TAP-deficient and TAP-proficient T2 cells. Both immunoproteasome and surface levels of B*2704 were induced by IFN-gamma, but this had little effect on allorecognition. Thus, except for the differential effects of tapasin on surface expression, the tapasin, TAP, and immunoproteasome dependency of B*2704 for maturation, surface expression, and T cell recognition are similar to B*2705, indicating that basic immunological features are shared by the two major HLA-B27 allotypes associated to ankylosing spondylitis in human populations.
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Affiliation(s)
- Verónica Montserrat
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid), Facultad de Ciencias, Universidad Autónoma, Madrid, Spain
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19
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Elliott T, Williams A. The optimization of peptide cargo bound to MHC class I molecules by the peptide-loading complex. Immunol Rev 2005; 207:89-99. [PMID: 16181329 DOI: 10.1111/j.0105-2896.2005.00311.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Major histocompatibility complex (MHC) class I complexes present peptides from both self and foreign intracellular proteins on the surface of most nucleated cells. The assembled heterotrimeric complexes consist of a polymorphic glycosylated heavy chain, non-polymorphic beta(2) microglobulin, and a peptide of typically nine amino acids in length. Assembly of the class I complexes occurs in the endoplasmic reticulum and is assisted by a number of chaperone molecules. A multimolecular unit termed the peptide-loading complex (PLC) is integral to this process. The PLC contains a peptide transporter (transporter associated with antigen processing), a thiooxido-reductase (ERp57), a glycoprotein chaperone (calreticulin), and tapasin, a class I-specific chaperone. We suggest that class I assembly involves a process of optimization where the peptide cargo of the complex is edited by the PLC. Furthermore, this selective peptide loading is biased toward peptides that have a longer off-rate from the assembled complex. We suggest that tapasin is the key chaperone that directs this action of the PLC with secondary contributions from calreticulin and possibly ERp57. We provide a framework model for how this may operate at the molecular level and draw parallels with the proposed mechanism of action of human leukocyte antigen-DM for MHC class II complex optimization.
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Affiliation(s)
- Tim Elliott
- Cancer Sciences Division, University of Southampton School of Medicine, Southampton General Hospital, Southampton, UK.
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20
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Sesma L, Galocha B, Vázquez M, Purcell AW, Marcilla M, McCluskey J, López de Castro JA. Qualitative and Quantitative Differences in Peptides Bound to HLA-B27 in the Presence of Mouse versus Human Tapasin Define a Role for Tapasin as a Size-Dependent Peptide Editor. THE JOURNAL OF IMMUNOLOGY 2005; 174:7833-44. [PMID: 15944288 DOI: 10.4049/jimmunol.174.12.7833] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Tapasin (Tpn) is a chaperone of the endoplasmic reticulum involved in peptide loading to MHC class I proteins. The influence of mouse Tpn (mTpn) on the HLA-B*2705-bound peptide repertoire was analyzed to characterize the species specificity of this chaperone. B*2705 was expressed on Tpn-deficient human 721.220 cells cotransfected with human (hTpn) or mTpn. The heterodimer to beta(2)-microglobulin-free H chain ratio on the cell surface was reduced with mTpn, suggesting lower B*2705 stability. The B*2705-bound peptide repertoires loaded with hTpn or mTpn shared 94-97% identity, although significant differences in peptide amount were observed in 16-17% of the shared ligands. About 3-6% of peptides were bound only with either hTpn or mTpn. Nonamers differentially bound with mTpn had less suitable anchor residues and bound B*2705 less efficiently in vitro than those loaded only with hTpn or shared nonamers. Decamers showed a different pattern: those found only with mTpn had similarly suitable residues as shared decamers and bound B*2705 with high efficiency. Peptides differentially presented by B*2705 on human or mouse cells showed an analogous pattern of residue suitability, suggesting that the effect of mTpn on B*2705 loading is comparable in both cell types. Thus, mTpn has quantitative and qualitative effects on the B*2705-bound peptide repertoire, impairing presentation of some suitable ligands and allowing others with suboptimal anchor residues and lower affinity to be presented. Our results favor a size-dependent peptide editing role of Tpn for HLA-B*2705 that is species-dependent and suboptimally performed, at least for nonamers, by mTpn.
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Affiliation(s)
- Laura Sesma
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid), Facultad de Ciencias, Universidad Autónoma, Madrid, Spain
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21
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Howarth M, Williams A, Tolstrup AB, Elliott T. Tapasin enhances MHC class I peptide presentation according to peptide half-life. Proc Natl Acad Sci U S A 2004; 101:11737-42. [PMID: 15286279 PMCID: PMC511045 DOI: 10.1073/pnas.0306294101] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Understanding how peptides are selected for presentation by MHC class I is crucial to vaccination strategies based on cytotoxic T lymphocyte priming. We have studied this selection of the MHC class I peptide repertoire in terms of the presentation of a series of individual peptides with a wide range of binding to MHC class I. This series was expressed as minigenes, and the presentation of each peptide variant was determined with the same MHC class I peptide-specific antibody. In wild-type cells, the hierarchy of presentation followed peptide half-life. This hierarchy broke down in cells lacking tapasin but not in cells lacking calreticulin or in cells lacking transporter associated with antigen processing-associated ERp57. We demonstrate a key role for tapasin in shaping the MHC class I peptide repertoire, as enhancement of presentation in the presence of tapasin correlated with peptide half-life.
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Affiliation(s)
- Mark Howarth
- Medical Research Council Human Immunology Unit, Oxford University, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
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22
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Zarling AL, Luckey CJ, Marto JA, White FM, Brame CJ, Evans AM, Lehner PJ, Cresswell P, Shabanowitz J, Hunt DF, Engelhard VH. Tapasin Is a Facilitator, Not an Editor, of Class I MHC Peptide Binding. THE JOURNAL OF IMMUNOLOGY 2003; 171:5287-95. [PMID: 14607930 DOI: 10.4049/jimmunol.171.10.5287] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Tapasin has been proposed to function as a peptide editor to displace lower affinity peptides and/or to favor the binding of high affinity peptides. Consistent with this, cell surface HLA-B8 molecules in tapasin-deficient cells were less stable and the peptide repertoire was substantially altered. However, the binding affinities of peptides expressed in the absence of tapasin were unexpectedly higher, not lower. The peptide repertoire from cells expressing soluble tapasin was similar in both appearance and affinity to that presented in the presence of full-length tapasin, but the HLA-B8 molecules showed altered cell surface stability characteristics. Similarly, the binding affinities of HLA-A*0201-associated peptides from tapasin(+) and tapasin(-) cells were equivalent, although steady state HLA-A*0201 cell surface expression was decreased and the molecules demonstrated reduced cell surface stability on tapasin(-) cells. These data are inconsistent with a role for tapasin as a peptide editor. Instead, we propose that tapasin acts as a peptide facilitator. In this role, it stabilizes the peptide-free conformation of class I MHC molecules in the endoplasmic reticulum and thus increases the number and variety of peptides bound to class I MHC. Full-length tapasin then confers additional stability on class I MHC molecules that are already associated with peptides.
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Affiliation(s)
- Angela L Zarling
- Carter Immunology Center and Department of Microbiology, University of Virginia, Charlottesville, VA 22908, USA
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23
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Momburg F, Tan P. Tapasin-the keystone of the loading complex optimizing peptide binding by MHC class I molecules in the endoplasmic reticulum. Mol Immunol 2002; 39:217-33. [PMID: 12200052 DOI: 10.1016/s0161-5890(02)00103-7] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
MHC class I molecules are loaded with peptides that mostly originate from the degradation of cytosolic protein antigens and that are translocated across the endoplasmic reticulum (ER) membrane by the transporter associated with antigen processing (TAP). The ER-resident molecule tapasin (Tpn) is uniquely dedicated to tether class I molecules jointly with the chaperone calreticulin (Crt) and the oxidoreductase ERp57 to TAP. As learned from the study of a Tpn-deficient cell line and from mice harboring a disrupted Tpn gene, the transient association of class I molecules with Tpn and TAP is critically important for the stabilization of class I molecules and the optimization of the peptide cargo presented to cytotoxic T cells. The different functions of molecular domains of Tpn and the highly coordinated formation of the TAP-associated peptide loading complex will also be discussed in this review.
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Affiliation(s)
- F Momburg
- Department of Molecular Immunology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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