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Bonney EA. A Framework for Understanding Maternal Immunity. Immunol Allergy Clin North Am 2023; 43:e1-e20. [PMID: 37179052 PMCID: PMC10484232 DOI: 10.1016/j.iac.2023.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
This is an alternative and controversial framing of the data relevant to maternal immunity. It argues for a departure from classical theory to view, interrogate and interpret existing data.
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Affiliation(s)
- Elizabeth A Bonney
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Vermont Robert Larner College of Medicine, Given Building, Room C246, 89 Beaumont Avenue, Burlington, VT 05405, USA.
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2
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Saidakova EV. Lymphopenia and Mechanisms of T-Cell Regeneration. CELL AND TISSUE BIOLOGY 2022; 16:302-311. [PMID: 35967247 PMCID: PMC9358362 DOI: 10.1134/s1990519x2204006x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/11/2022] [Accepted: 01/11/2022] [Indexed: 11/24/2022]
Abstract
Chronic lymphopenia, in particular, T-lymphocyte deficiency, increases the risk of death from cancer, cardiovascular and respiratory diseases and serves as a risk factor for a severe course and poor outcome of infectious diseases such as COVID-19. The regeneration of T-lymphocytes is a complex multilevel process, many questions of which still remain unanswered. The present review considers two main pathways of increasing the T-cell number in lymphopenia: production in the thymus and homeostatic proliferation in the periphery. Literature data on the signals that regulate each pathway are summarized. Their contribution to the quantitative and qualitative restoration of the immune cell pool is analyzed. The features of CD4+ and CD8+ T-lymphocytes’ regeneration are considered.
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Affiliation(s)
- E. V. Saidakova
- Institute of Ecology and Genetics of Microorganisms, Ural Branch, Russian Academy of Sciences—Branch of Perm Federal Research Center, Ural Branch, Russian Academy of Sciences, 614081 Perm, Russia
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3
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Zhou Y, Leng X, Mo C, Zou Q, Liu Y, Wang Y. The p53 effector Perp mediates the persistence of CD4 + effector memory T-cell undergoing lymphopenia-induced proliferation. Immunol Lett 2020; 224:14-20. [PMID: 32473185 DOI: 10.1016/j.imlet.2020.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 05/06/2020] [Accepted: 05/11/2020] [Indexed: 12/20/2022]
Abstract
Under lymphopenic conditions, the rapid spontaneous proliferation produces cells that robustly differentiate into effector memory T (TEM) cells, and the aberrant expansion is preferentially driven by self-antigens. The pool size of effector memory T-cell is governed by a complex homeostatic balance between proliferation and death. Perp is a critical effector involved in the p53-dependent apoptotic pathway and widely expressed in mammalian tissues. We have previously shown that Perp has a prominent role in activation-induced cell death of peripheral Th17 cells. Here, we show that Peripheral Perp-/-CD4+ TEM cells outcompete wild type TEM cells for access to splenic niches in vivo. The skewing of the Perp-/- TEM cells compartment was not the result of a difference in lymphopenia-induced proliferation, but the resistance to apoptosis, particularly after anti-Fas treatment. Data presented in this work indicate that Perp mediates the persistence of CD4+ TEM cells in irradiation-induced lymphopenic settings.
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Affiliation(s)
- Yan Zhou
- Department of Emergency, West China Second University Hospital and Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects, Ministry of Education, Sichuan University, Chengdu, China.
| | - Xiao Leng
- Department of Immunology, School of Basic Medical Sciences, Chengdu Medical College, Chengdu, China.
| | - Chunfen Mo
- Department of Immunology, School of Basic Medical Sciences, Chengdu Medical College, Chengdu, China.
| | - Qiang Zou
- Department of Immunology, School of Basic Medical Sciences, Chengdu Medical College, Chengdu, China.
| | - Yang Liu
- Department of Immunology, School of Basic Medical Sciences, Chengdu Medical College, Chengdu, China.
| | - Yantang Wang
- Department of Immunology, School of Basic Medical Sciences, Chengdu Medical College, Chengdu, China.
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4
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Hojo MA, Masuda K, Hojo H, Nagahata Y, Yasuda K, Ohara D, Takeuchi Y, Hirota K, Suzuki Y, Kawamoto H, Kawaoka S. Identification of a genomic enhancer that enforces proper apoptosis induction in thymic negative selection. Nat Commun 2019; 10:2603. [PMID: 31197149 PMCID: PMC6565714 DOI: 10.1038/s41467-019-10525-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 05/19/2019] [Indexed: 12/23/2022] Open
Abstract
During thymic negative selection, autoreactive thymocytes carrying T cell receptor (TCR) with overtly strong affinity to self-MHC/self-peptide are removed by Bim-dependent apoptosis, but how Bim is specifically regulated to link TCR activation and apoptosis induction is unclear. Here we identify a murine T cell-specific genomic enhancer EBAB (Bub1-Acoxl-Bim), whose deletion leads to accumulation of thymocytes expressing high affinity TCRs. Consistently, EBAB knockout mice have defective negative selection and fail to delete autoreactive thymocytes in various settings, with this defect accompanied by reduced Bim expression and apoptosis induction. By contrast, EBAB is dispensable for maintaining peripheral T cell homeostasis via Bim-dependent pathways. Our data thus implicate EBAB as an important, developmental stage-specific regulator of Bim expression and apoptosis induction to enforce thymic negative selection and suppress autoimmunity. Our study unravels a part of genomic enhancer codes that underlie complex and context-dependent gene regulation in TCR signaling.
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Affiliation(s)
- Miki Arai Hojo
- Graduate School of Frontier Science, The University of Tokyo, Kashiwa-shi, Chiba, 277-8562, Japan
- The Thomas N. Sato BioMEC-X Laboratories, Advanced Telecommunications Research Institute International (ATR), Soraku-gun, Kyoto, 619-0237, Japan
| | - Kyoko Masuda
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto-shi, Kyoto, 606-8507, Japan
| | - Hiroaki Hojo
- The Thomas N. Sato BioMEC-X Laboratories, Advanced Telecommunications Research Institute International (ATR), Soraku-gun, Kyoto, 619-0237, Japan
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto-shi, Kyoto, 606-8507, Japan
- ERATO Sato Live Bio-forecasting Project, Japan Science and Technology Agency (JST), Soraku-gun, Kyoto, 619-0237, Japan
| | - Yosuke Nagahata
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto-shi, Kyoto, 606-8507, Japan
| | - Keiko Yasuda
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto-shi, Kyoto, 606-8507, Japan
| | - Daiya Ohara
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto-shi, Kyoto, 606-8507, Japan
| | - Yusuke Takeuchi
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto-shi, Kyoto, 606-8507, Japan
| | - Keiji Hirota
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto-shi, Kyoto, 606-8507, Japan
| | - Yutaka Suzuki
- Graduate School of Frontier Science, The University of Tokyo, Kashiwa-shi, Chiba, 277-8562, Japan
| | - Hiroshi Kawamoto
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto-shi, Kyoto, 606-8507, Japan
| | - Shinpei Kawaoka
- The Thomas N. Sato BioMEC-X Laboratories, Advanced Telecommunications Research Institute International (ATR), Soraku-gun, Kyoto, 619-0237, Japan.
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto-shi, Kyoto, 606-8507, Japan.
- ERATO Sato Live Bio-forecasting Project, Japan Science and Technology Agency (JST), Soraku-gun, Kyoto, 619-0237, Japan.
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5
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Fortner KA, Bond JP, Austin JW, Boss JM, Budd RC. The molecular signature of murine T cell homeostatic proliferation reveals both inflammatory and immune inhibition patterns. J Autoimmun 2017; 82:47-61. [PMID: 28551033 PMCID: PMC5902411 DOI: 10.1016/j.jaut.2017.05.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 05/04/2017] [Accepted: 05/09/2017] [Indexed: 01/21/2023]
Abstract
T lymphocyte homeostatic proliferation, driven by the engagement of T cell antigen receptor with self-peptide/major histocompatibility complexes, and signaling through the common γ-chain-containing cytokine receptors, is critical for the maintenance of the T cell compartment and is regulated by the Fas death receptor (Fas, CD95). In the absence of Fas, Fas-deficient lymphoproliferation spontaneous mutation (lpr) mice accumulate homeostatically expanded T cells. The functional consequences of sequential rounds of homeostatic expansion are not well defined. We thus examined the gene expression profiles of murine wild-type and Fas-deficient lpr CD8+ T cell subsets that have undergone different amounts of homeostatic proliferation as defined by their level of CD44 expression, and the CD4-CD8-TCRαβ+ T cell subset that results from extensive homeostatic expansion of CD8+ T cells. Our studies show that recurrent T cell homeostatic proliferation results in global gene expression changes, including the progressive upregulation of both cytolytic proteins such as Fas-Ligand and granzyme B as well as inhibitory proteins such as programmed cell death protein 1 (PD-1) and lymphocyte activating 3 (Lag3). These findings provide an explanation for how augmented T cell homeostatic expansion could lead to the frequently observed clinical paradox of simultaneous autoinflammatory and immunodeficiency syndromes and provide further insight into the regulatory programs that control chronically stimulated T cells.
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Affiliation(s)
- Karen A Fortner
- Department of Medicine, The University of Vermont College of Medicine, Burlington, VT 05405-0068, USA.
| | - Jeffrey P Bond
- Department of Microbiology and Molecular Genetics, The University of Vermont College of Medicine, Burlington, VT 05405-0068, USA
| | - James W Austin
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Jeremy M Boss
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Ralph C Budd
- Department of Medicine, The University of Vermont College of Medicine, Burlington, VT 05405-0068, USA
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Anstee NS, Vandenberg CJ, Campbell KJ, Hughes PD, O'Reilly LA, Cory S. Overexpression of Mcl-1 exacerbates lymphocyte accumulation and autoimmune kidney disease in lpr mice. Cell Death Differ 2016; 24:397-408. [PMID: 27813531 PMCID: PMC5344201 DOI: 10.1038/cdd.2016.125] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 09/12/2016] [Accepted: 09/30/2016] [Indexed: 12/23/2022] Open
Abstract
Cell death by apoptosis has a critical role during embryonic development and in maintaining tissue homeostasis. In mammals, there are two converging apoptosis pathways: the 'extrinsic' pathway, which is triggered by engagement of cell surface 'death receptors' such as Fas/APO-1; and the 'intrinsic' pathway, which is triggered by diverse cellular stresses, and is regulated by pro-survival and pro-apoptotic members of the Bcl-2 family of proteins. Pro-survival Mcl-1, which can block activation of the pro-apoptotic proteins, Bax and Bak, appears critical for the survival and maintenance of multiple haemopoietic cell types. To investigate the impact on haemopoiesis of simultaneously inhibiting both apoptosis pathways, we introduced the vavP-Mcl-1 transgene, which causes overexpression of Mcl-1 protein in all haemopoietic lineages, into Faslpr/lpr mice, which lack functional Fas and are prone to autoimmunity. The combined mutations had a modest impact on myelopoiesis, primarily an increase in the macrophage/monocyte population in Mcl-1tg/lpr mice compared with lpr or Mcl-1tg mice. The impact on lymphopoiesis was striking, with a marked elevation in all major lymphoid subsets, including the non-conventional double-negative (DN) T cells (TCRβ+CD4-CD8-B220+) characteristic of Faslpr/lpr mice. Of note, the onset of autoimmunity was markedly accelerated in Mcl-1tg/lpr mice compared with lpr mice, and this was preceded by an increase in immunoglobulin (Ig)-producing cells and circulating autoantibodies. This degree of impact was surprising, given the relatively mild phenotype conferred by the vavP-Mcl-1 transgene by itself: a two- to threefold elevation of peripheral B and T cells, no significant increase in the non-conventional DN T-cell population and no autoimmune disease. Comparison of the phenotype with that of other susceptible mice suggests that the development of autoimmune disease in Mcl-1tg/lpr mice may be influenced not only by Ig-producing cells but also other haemopoietic cell types.
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Affiliation(s)
- Natasha S Anstee
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Cassandra J Vandenberg
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Kirsteen J Campbell
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Peter D Hughes
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Lorraine A O'Reilly
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Suzanne Cory
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
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7
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Niss O, Sholl A, Bleesing JJ, Hildeman DA. IL-10/Janus kinase/signal transducer and activator of transcription 3 signaling dysregulates Bim expression in autoimmune lymphoproliferative syndrome. J Allergy Clin Immunol 2014; 135:762-70. [PMID: 25174872 DOI: 10.1016/j.jaci.2014.07.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 05/26/2014] [Accepted: 07/02/2014] [Indexed: 12/13/2022]
Abstract
BACKGROUND Autoimmune lymphoproliferative syndrome (ALPS) is a human disorder of T cell homeostasis caused by mutations that impair FAS-mediated apoptosis. A defining characteristic of ALPS is the expansion of double negative T cells (DNTC). Relatively little is known about how defective FAS-driven cell death and the Bcl-2 apoptotic pathway intersect in ALPS patients. OBJECTIVE We studied changes in Bcl-2 family member expression in ALPS to determine whether the Bcl-2 pathway might provide a therapeutic target. METHODS We used flow cytometry to analyze the expression of pro- and anti-apoptotic Bcl-2 family members in T cells from 12 ALPS patients and determined the in vitro sensitivity of ALPS DNTC to the pro-apoptotic BH3 mimetic, ABT-737. RESULTS The pro-apoptotic molecule, Bim, was significantly elevated in DNTC. Although no general pattern of individual anti-apoptotic Bcl-2 family members emerged, increased expression of Bim was always accompanied by increased expression of at least 1 anti-apoptotic Bcl-2 family member. Strikingly, Bim levels in DNTC correlated significantly with serum IL-10 in ALPS patients, and IL-10 was sufficient to mildly induce Bim in normal and ALPS T cells via a Janus kinase/signal transducer and activator of transcription 3-dependent mechanism. Finally, ABT-737 preferentially killed ALPS DNTC in vitro. CONCLUSION Combined, these data show that an IL-10/Janus kinase/signal transducer and activator of transcription 3 pathway drives Bim expression in ALPS DNTC, which renders them sensitive to BH3 mimetics, uncovering a potentially novel therapeutic approach to ALPS.
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Affiliation(s)
- Omar Niss
- Cancer and Blood Disease Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Allyson Sholl
- Division of Cellular and Molecular Immunology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio
| | - Jack J Bleesing
- Cancer and Blood Disease Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - David A Hildeman
- Division of Cellular and Molecular Immunology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio.
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8
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Weil R. Does antigen masking by ubiquitin chains protect from the development of autoimmune diseases? Front Immunol 2014; 5:262. [PMID: 24917867 PMCID: PMC4042494 DOI: 10.3389/fimmu.2014.00262] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 05/19/2014] [Indexed: 11/20/2022] Open
Abstract
Autoimmune diseases are characterized by the production of antibodies against self-antigens and generally arise from a failure of central or peripheral tolerance. However, these diseases may develop when newly appearing antigens are not recognized as self by the immune system. The mechanism by which some antigens are “invisible” to the immune system is not completely understood. Apoptotic and complement system defects or autophagy imbalance can generate this antigenic autoreactivity. Under particular circumstances, cellular debris containing autoreactive antigens can be recognized by innate immune receptors or other sensors and can eventually lead to autoimmunity. Ubiquitination may be one of the mechanisms protecting autoreactive antigens from the immune system that, if disrupted, can lead to autoimmunity. Ubiquitination is an essential post-translational modification used by cells to target proteins for degradation or to regulate other intracellular processes. The level of ubiquitination is regulated during T cell tolerance and apoptosis and E3 ligases have emerged as a crucial signaling pathway for the regulation of T cell tolerance toward self-antigens. I propose here that an unrecognized role of ubiquitin and ubiquitin-like proteins could be to render intracellular or foreign antigens (present in cellular debris resulting from apoptosis, complement system, or autophagy defects) invisible to the immune system in order to prevent the development of autoimmunity.
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Affiliation(s)
- Robert Weil
- Unité de Signalisation Moléculaire et Activation Cellulaire, CNRS URA 2582, Institut Pasteur , Paris , France
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9
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Luo XP. Phospholipase Cε-1 inhibits p53 expression in lung cancer. Cell Biochem Funct 2013; 32:294-8. [PMID: 24357048 DOI: 10.1002/cbf.3015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 10/14/2013] [Accepted: 10/21/2013] [Indexed: 01/03/2023]
Affiliation(s)
- Xue-ping Luo
- Department of Cardiothoracic Surgery; Nanhai People's Hospital, the Nanfang Medical University Affiliated Nanhai Hospital; Foshan China
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10
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Bim mediates the elimination of functionally unfit Th1 responders from the memory pool. PLoS One 2013; 8:e67363. [PMID: 23840678 PMCID: PMC3696111 DOI: 10.1371/journal.pone.0067363] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 05/17/2013] [Indexed: 12/20/2022] Open
Abstract
Selective clonal deletion in the CD4+ T cell compartment during the transition from effector to memory is accompanied by enhanced expression of the pro-apoptotic Bcl-2 family member Bim. Here, we show that Bim deficiency enables the survival of poorly functional Th1 responders that are normally eliminated during contraction. However, rescued bim−/− CD4+ “memory” T cells continued to demonstrate deficient effector functions, poor sensitivity to antigen and an inability to respond to secondary challenge. Our results demonstrate that Bim activity plays a key role in shaping the CD4+ memory T cell repertoire, ensuring the emergence of highly functional CD4+ memory T cells and the elimination of Th1 effector cells with sub-optimal function. We propose that Bim is a key mediator of T cell death in the absence of appropriate TCR-driven activation and differentiation.
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Shepard MT, Bonney EA. PD-1 regulates T cell proliferation in a tissue and subset-specific manner during normal mouse pregnancy. Immunol Invest 2013; 42:385-408. [PMID: 23782245 DOI: 10.3109/08820139.2013.782317] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The regulation of T cell homeostasis during pregnancy has important implications for maternal tolerance and immunity. Evidence suggests that Programmed Death-1 (PD-1) participates in regulation of T cell homeostasis and peripheral tolerance. To examine the contribution of PD-1 signaling on T cell homeostasis during normal mouse pregnancy, we examined T cell number or proportion, PD-1 expression, proliferation, and apoptosis by flow cytometry, BrdU incorporation, and TUNEL assay in pregnant mice given anti-PD-1 blocking antibody or control on days 10, 12, and 14 of gestation. We observed tissue, treatment, and T cell-specific differences in PD-1 expression. Both pregnancy and PD-1 blockade increased T cell proliferation in the spleen, yet this effect was limited to CD4 T cells in the uterine- draining nodes. In the uterus, PD-1 blockade markedly altered the composition of the T cell pool. These studies support the idea that pregnancy is a state of dynamic T cell homeostasis and suggest that this state is partially supported by PD-1 signaling.
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Affiliation(s)
- Michelle T Shepard
- University of Vermont College of Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, Burlington, VT 05405, USA
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12
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Juvet SC, Thomson CW, Kim EY, Joe B, Adeyi O, Zhang L. FcRγ promotes T cell apoptosis in Fas-deficient mice. J Autoimmun 2013; 42:80-93. [DOI: 10.1016/j.jaut.2012.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 12/07/2012] [Accepted: 12/10/2012] [Indexed: 10/27/2022]
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Molecular basis for the interplay of apoptosis and proliferation mediated by Bcl-xL:Bim interactions in pancreatic cancer cells. Biochem Biophys Res Commun 2012; 422:596-601. [PMID: 22609401 DOI: 10.1016/j.bbrc.2012.05.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 05/09/2012] [Indexed: 11/24/2022]
Abstract
A major mechanism through which cancer cells avoid apoptosis is by promoting the association of anti-apoptotic members of the pro-survival Bcl-2 protein family (like Bcl-2 and Bcl-xL) with BH(3) domain-only proteins (like Bim and Bid). Apoptosis and cell proliferation have been shown to be linked for many cancers but the molecular basis for this link is far from understood. We have identified the Bcl-xL:Bim protein-protein interface as a direct regulator of proliferation and apoptosis in pancreatic cancer cells. We were able to predict and subsequently verify experimentally the effect of various Bcl-xL single-point mutants (at the position A142) on binding to Bim by structural analysis and computational modeling of the inter-residue interactions at the Bcl-xL:Bim protein-protein interface. The mutants A142N, A142Q, and A142Y decreased binding of Bim to Bcl-xL and A142S increased this binding. The Bcl-xL mutants, with decreased affinity for Bim, caused an increase in apoptosis and a corresponding decrease in cell proliferation. However, we could prevent these effects by introducing a small interfering RNA (siRNA) targeted at Bim. These results show a novel role played by the Bcl-xL:Bim interaction in regulating proliferation of pancreatic cancer cells at the expense of apoptosis. This study presents a physiologically relevant model of the Bcl-xL:Bim interface that can be used for rational therapeutic design for the inhibition of proliferation and cancer cell resistance to apoptosis.
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14
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Choi O, Heathcote DA, Ho KK, Müller PJ, Ghani H, Lam EWF, Ashton-Rickardt PG, Rutschmann S. A deficiency in nucleoside salvage impairs murine lymphocyte development, homeostasis, and survival. THE JOURNAL OF IMMUNOLOGY 2012; 188:3920-7. [PMID: 22407915 DOI: 10.4049/jimmunol.1102587] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The homeostasis of the immune system is tightly controlled by both cell-extrinsic and -intrinsic mechanisms. These regulators, not all known to date, drive cells in and out of quiescence when and where required to allow the immune system to function. In this article, we describe a deficiency in deoxycytidine kinase (DCK), one of the major enzymes of the nucleoside salvage pathway, which affects peripheral T cell homeostatic proliferation and survival. As a result of an N-ethyl-N-nitrosourea-induced mutation in the last α helix of DCK, a functionally null protein has been generated in the mouse and affects the composition of the hematopoietic system. Both B and T lymphocyte development is impaired, leading to a state of chronic lymphopenia and to a significant increase in the number of myeloid cells and erythrocytes. In the periphery, we found that mutant lymphocytes adopt a CD44(high)CD62L(low) memory phenotype, with high levels of proliferation and apoptosis. These phenotypes are notably the result of a cell-extrinsic-driven lymphopenia-induced proliferation as wild-type cells transferred into DCK-deficient recipients adopt the same profile. In addition, DCK also regulates lymphocyte quiescence in a cell-intrinsic manner. These data establish dCK as a new regulator of hematopoietic integrity and lymphocyte quiescence and survival.
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Affiliation(s)
- Onjee Choi
- Section of Immunobiology, Faculty of Medicine, Imperial College London, London W12 0NN, UK
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15
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Fortner KA, Lees RK, MacDonald HR, Budd RC. Fas (CD95/APO-1) limits the expansion of T lymphocytes in an environment of limited T-cell antigen receptor/MHC contacts. Int Immunol 2011; 23:75-88. [PMID: 21266499 DOI: 10.1093/intimm/dxq466] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Fas-deficient mice (Fas(lpr/lpr)) and humans have profoundly dysregulated T lymphocyte homeostasis, which manifests as an accumulation of CD4(+) and CD8(+) T cells as well as an unusual population of CD4(-)CD8(-)TCRαβ(+) T cells. To date, no unifying model has explained both the increased T-cell numbers and the origin of the CD4(-)CD8(-)TCRαβ(+) T cells. As Fas(lpr/lpr) mice raised in a germ-free environment still manifest lymphadenopathy, we considered that this process is primarily driven by recurrent low-avidity TCR signaling in response to self-peptide/MHC as occurs during homeostatic proliferation. In these studies, we developed two independent systems to decrease the number of self-peptide/MHC contacts. First, expression of MHC class I was reduced in OT-I TCR transgenic mice. Although OT-I Fas(lpr/lpr) mice did not develop lymphadenopathy characteristic of Fas(lpr/lpr) mice, in the absence of MHC class I, OT-I Fas(lpr/lpr) T cells accumulated as both CD8(+) and CD4(-)CD8(-) T cells. In the second system, re-expression of β(2)m limited to thymic cortical epithelial cells of Fas(lpr/lpr) β(2)m-deficient mice yielded a model in which polyclonal CD8(+) thymocytes entered a peripheral environment devoid of MHC class I. These mice accumulated significantly greater numbers of CD4(-)CD8(-)TCRαβ(+) T cells than conventional Fas(lpr/lpr) mice. Thus, Fas shapes the peripheral T-cell repertoire by regulating the survival of a subset of T cells proliferating in response to limited self-peptide/MHC contacts.
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Affiliation(s)
- Karen A Fortner
- Immunobiology Program, Department of Medicine, The University of Vermont College of Medicine, Burlington, VT 05405-0068, USA.
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