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Liu T, Xia S. The Proteostasis of Thymic Stromal Cells in Health and Diseases. Protein J 2024; 43:447-463. [PMID: 38622349 DOI: 10.1007/s10930-024-10197-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/05/2024] [Indexed: 04/17/2024]
Abstract
The thymus is the key immune organ for the development of T cells. Different populations of thymic stromal cells interact with T cells, thereby controlling the dynamic development of T cells through their differentiation and function. Proteostasis represents a balance between protein expression, folding, and modification and protein clearance, and its fluctuation usually depends at least partially on related protein regulatory systems for further survival and effects. However, in terms of the substantial requirement for self-antigens and their processing burden, increasing evidence highlights that protein regulation contributes to the physiological effects of thymic stromal cells. Impaired proteostasis may expedite the progression of thymic involution and dysfunction, accompanied by the development of autoimmune diseases or thymoma. Hence, in this review, we summarize the regulation of proteostasis within different types of thymic stromal cells under physiological and pathological conditions to identify potential targets for thymic regeneration and immunotherapy.
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Affiliation(s)
- Ting Liu
- Department of Immunology, School of Medicine, Jiangsu University, 301, Xuefu Road, Zhenjiang, Jiangsu, 212013, China
| | - Sheng Xia
- Department of Immunology, School of Medicine, Jiangsu University, 301, Xuefu Road, Zhenjiang, Jiangsu, 212013, China.
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2
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Tundo GR, Sbardella D, Oddone F, Kudriaeva AA, Lacal PM, Belogurov AA, Graziani G, Marini S. At the Cutting Edge against Cancer: A Perspective on Immunoproteasome and Immune Checkpoints Modulation as a Potential Therapeutic Intervention. Cancers (Basel) 2021; 13:4852. [PMID: 34638337 PMCID: PMC8507813 DOI: 10.3390/cancers13194852] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/20/2021] [Accepted: 09/21/2021] [Indexed: 01/22/2023] Open
Abstract
Immunoproteasome is a noncanonical form of proteasome with enzymological properties optimized for the generation of antigenic peptides presented in complex with class I MHC molecules. This enzymatic property makes the modulation of its activity a promising area of research. Nevertheless, immunotherapy has emerged as a front-line treatment of advanced/metastatic tumors providing outstanding improvement of life expectancy, even though not all patients achieve a long-lasting clinical benefit. To enhance the efficacy of the currently available immunotherapies and enable the development of new strategies, a broader knowledge of the dynamics of antigen repertoire processing by cancer cells is needed. Therefore, a better understanding of the role of immunoproteasome in antigen processing and of the therapeutic implication of its modulation is mandatory. Studies on the potential crosstalk between proteasome modulators and immune checkpoint inhibitors could provide novel perspectives and an unexplored treatment option for a variety of cancers.
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Affiliation(s)
| | | | | | - Anna A. Kudriaeva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (A.A.K.)
| | - Pedro M. Lacal
- Laboratory of Molecular Oncology, IDI-IRCCS, 00167 Rome, Italy;
| | - Alexey A. Belogurov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (A.A.K.)
- Lomonosov Moscow State University, Leninskie Gory, 119991 Moscow, Russia
| | - Grazia Graziani
- Laboratory of Molecular Oncology, IDI-IRCCS, 00167 Rome, Italy;
- Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Stefano Marini
- Department of Clinical Sciences and Translational Medicine, University of Rome Tor Vergata, 00133 Rome, Italy;
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Frantzeskakis M, Takahama Y, Ohigashi I. The Role of Proteasomes in the Thymus. Front Immunol 2021; 12:646209. [PMID: 33815406 PMCID: PMC8017227 DOI: 10.3389/fimmu.2021.646209] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Accepted: 03/05/2021] [Indexed: 12/26/2022] Open
Abstract
The thymus provides a microenvironment that supports the generation and selection of T cells. Cortical thymic epithelial cells (cTECs) and medullary thymic epithelial cells (mTECs) are essential components of the thymic microenvironment and present MHC-associated self-antigens to developing thymocytes for the generation of immunocompetent and self-tolerant T cells. Proteasomes are multicomponent protease complexes that degrade ubiquitinated proteins and produce peptides that are destined to be associated with MHC class I molecules. cTECs specifically express thymoproteasomes that are essential for optimal positive selection of CD8+ T cells, whereas mTECs, which contribute to the establishment of self-tolerance in T cells, express immunoproteasomes. Immunoproteasomes are also detectable in dendritic cells and developing thymocytes, additionally contributing to T cell development in the thymus. In this review, we summarize the functions of proteasomes expressed in the thymus, focusing on recent findings pertaining to the functions of the thymoproteasomes and the immunoproteasomes.
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Affiliation(s)
- Melina Frantzeskakis
- Thymus Biology Section, Experimental Immunology Branch, National Cancer Institute, Bethesda, MD, United States
| | - Yousuke Takahama
- Thymus Biology Section, Experimental Immunology Branch, National Cancer Institute, Bethesda, MD, United States
| | - Izumi Ohigashi
- Division of Experimental Immunology, Institute of Advanced Medical Sciences, University of Tokushima, Tokushima, Japan
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Kasahara M. Role of immunoproteasomes and thymoproteasomes in health and disease. Pathol Int 2021; 71:371-382. [PMID: 33657242 DOI: 10.1111/pin.13088] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/11/2021] [Indexed: 12/14/2022]
Abstract
The proteasome is a multisubunit protease that degrades intracellular proteins into small peptides. Besides playing a pivotal role in many cellular processes indispensable for survival, it is involved in the production of peptides presented by major histocompatibility complex class I molecules. In addition to the standard proteasome shared in all eukaryotes, jawed vertebrates have two specialized forms of proteasome known as immunoproteasomes and thymoproteasomes. The immunoproteasome, which contains cytokine-inducible catalytic subunits with distinct cleavage specificities, produces peptides presented by class I molecules more efficiently than the standard proteasome. The thymoproteasome, which contains a unique catalytic subunit β5t, is a tissue-specific proteasome expressed exclusively in cortical thymic epithelial cells. It plays a critical role in CD8+ cytotoxic T cell development via positive selection. This review provides a brief overview on the structure and function of these specialized forms of proteasome and their involvement in human disease.
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Affiliation(s)
- Masanori Kasahara
- Department of Pathology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Hokkaido, Japan
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Alawam AS, Anderson G, Lucas B. Generation and Regeneration of Thymic Epithelial Cells. Front Immunol 2020; 11:858. [PMID: 32457758 PMCID: PMC7221188 DOI: 10.3389/fimmu.2020.00858] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 04/15/2020] [Indexed: 01/04/2023] Open
Abstract
The thymus is unique in its ability to support the maturation of phenotypically and functionally distinct T cell sub-lineages. Through its combined production of MHC-restricted conventional CD4+ and CD8+, and Foxp3+ regulatory T cells, as well as non-conventional CD1d-restricted iNKT cells and invariant γδT cells, the thymus represents an important orchestrator of immune system development and control. It is now clear that thymus function is largely determined by the availability of stromal microenvironments. These specialized areas emerge during thymus organogenesis and are maintained throughout life. They are formed from both epithelial and mesenchymal components, and collectively they support a stepwise program of thymocyte development. Of these stromal cells, cortical, and medullary thymic epithelial cells represent functional components of thymic microenvironments in both the cortex and medulla. Importantly, a key feature of thymus function is that levels of T cell production are not constant throughout life. Here, multiple physiological factors including aging, stress and pregnancy can have either short- or long-term detrimental impact on rates of thymus function. Here, we summarize our current understanding of the development and function of thymic epithelial cells, and relate this to strategies to protect and/or restore thymic epithelial cell function for therapeutic benefit.
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Affiliation(s)
- Abdullah S Alawam
- Institute for Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Graham Anderson
- Institute for Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Beth Lucas
- Institute for Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
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Kondo K, Ohigashi I, Takahama Y. Thymus machinery for T-cell selection. Int Immunol 2020; 31:119-125. [PMID: 30476234 DOI: 10.1093/intimm/dxy081] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 11/20/2018] [Indexed: 01/01/2023] Open
Abstract
An immunocompetent and self-tolerant pool of naive T cells is formed in the thymus through the process of repertoire selection. T cells that are potentially capable of responding to foreign antigens are positively selected in the thymic cortex and are further selected in the thymic medulla to help prevent self-reactivity. The affinity between T-cell antigen receptors expressed by newly generated T cells and self-peptide-major histocompatibility complexes displayed in the thymic microenvironments plays a key role in determining the fate of developing T cells during thymic selection. Recent advances in our knowledge of the biology of thymic epithelial cells have revealed unique machinery that contributes to positive and negative selection in the thymus. In this article, we summarize recent findings on thymic T-cell selection, focusing on the machinery unique to thymic epithelial cells.
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Affiliation(s)
- Kenta Kondo
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.,Division of Experimental Immunology, Institute of Advanced Medical Sciences, University of Tokushima, Kuramoto, Tokushima, Japan
| | - Izumi Ohigashi
- Division of Experimental Immunology, Institute of Advanced Medical Sciences, University of Tokushima, Kuramoto, Tokushima, Japan
| | - Yousuke Takahama
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.,Division of Experimental Immunology, Institute of Advanced Medical Sciences, University of Tokushima, Kuramoto, Tokushima, Japan
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The immunoproteasome and thymoproteasome: functions, evolution and human disease. Nat Immunol 2018; 19:923-931. [PMID: 30104634 DOI: 10.1038/s41590-018-0186-z] [Citation(s) in RCA: 195] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 07/12/2018] [Accepted: 07/19/2018] [Indexed: 01/12/2023]
Abstract
The basic principle of adaptive immunity is to strictly discriminate between self and non-self, and a central challenge to overcome is the enormous variety of pathogens that might be encountered. In cell-mediated immunity, immunological discernment takes place at a molecular or cellular level. Central to both mechanisms of discernment is the generation of antigenic peptides associated with MHC class I molecules, which is achieved by a proteolytic complex called the proteasome. To adequately accomplish the discrimination between self and non-self that is essential for adaptive immunity and self-tolerance, two proteasome subtypes have evolved via gene duplication: the immunoproteasome and the thymoproteasome. In this Review, we describe various aspects of these immunity-dedicated proteasomes, from their discovery to recent findings.
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