1
|
Chu CF, Feng HK, Sun KH, Hsu CL, Dzhagalov IL. Examination of Fas-Induced Apoptosis of Murine Thymocytes in Thymic Tissue Slices Reveals That Fas Is Dispensable for Negative Selection. Front Cell Dev Biol 2020; 8:586807. [PMID: 33195241 PMCID: PMC7609743 DOI: 10.3389/fcell.2020.586807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 09/30/2020] [Indexed: 11/13/2022] Open
Abstract
The death receptor Fas can induce cell death through the extrinsic pathway of apoptosis in a variety of cells, including developing thymocytes. Although Fas-induced cell death has been researched and modeled extensively, most of the studies have been done in vitro because of the lethality of Fas triggering in vivo. Thus, little is known about the time line of this type of cell death in vivo, specifically, how does the presence of macrophages and pro-survival cytokines affect apoptosis progression. In addition, although the sequence and timing of events during intrinsic pathway activation in thymocytes in situ have been described, no corresponding data for the extrinsic pathway are available. To address this gap in our knowledge, we established a novel system to study Fas-induced thymocyte cell death using tissue explants. We found that within 1 h of Fas ligation, caspase 3 was activated, within 2 h phosphatidylserine was externalized to serve as an "eat-me" signal, and at the same time, we observed signs of cell loss, likely due to efferocytosis. Both caspase 3 activation and phosphatidylserine exposure were critical for cell loss. Although Fas ligand (FasL) was delivered simultaneously to all cells, we observed significant variation in the entry into the cell death pathway. This model also allowed us to revisit the role of Fas in negative selection, and we ruled out an essential part for it in the deletion of autoreactive thymocytes. Our work provides a timeline for the apoptosis-associated events following Fas triggering in situ and confirms the lack of involvement of Fas in the negative selection of thymocytes.
Collapse
Affiliation(s)
- Chang-Feng Chu
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
| | - Hsing-Kai Feng
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
| | - Kuang-Hui Sun
- Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Chia-Lin Hsu
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
| | - Ivan L Dzhagalov
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
| |
Collapse
|
2
|
A rheostat tuning thymic selection. Nat Immunol 2017. [PMID: 28632719 DOI: 10.1038/ni.3778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
3
|
Tuzlak S, Kaufmann T, Villunger A. Interrogating the relevance of mitochondrial apoptosis for vertebrate development and postnatal tissue homeostasis. Genes Dev 2017; 30:2133-2151. [PMID: 27798841 DOI: 10.1101/gad.289298.116] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
"Programmed cell death or 'apoptosis' is critical for organogenesis during embryonic development and tissue homeostasis in the adult. Its deregulation can contribute to a broad range of human pathologies, including neurodegeneration, cancer, or autoimmunity…" These or similar phrases have become generic opening statements in many reviews and textbooks describing the physiological relevance of apoptotic cell death. However, while the role in disease has been documented beyond doubt, facilitating innovative drug discovery, we wonder whether the former is really true. What goes wrong in vertebrate development or in adult tissue when the main route to apoptotic cell death, controlled by the BCL2 family, is impaired? Such scenarios have been mimicked by deletion of one or more prodeath genes within the BCL2 family, and gene targeting studies in mice exploring the consequences have been manifold. Many of these studies were geared toward understanding the role of BCL2 family proteins and mitochondrial apoptosis in disease, whereas fewer focused in detail on their role during normal development or tissue homeostasis, perhaps also due to an irritating lack of phenotype. Looking at these studies, the relevance of classical programmed cell death by apoptosis for development appears rather limited. Together, these many studies suggest either highly selective and context-dependent contributions of mitochondrial apoptosis or significant redundancy with alternative cell death mechanisms, as summarized and discussed here.
Collapse
Affiliation(s)
- Selma Tuzlak
- Division of Developmental Immunology, Biocenter, Medical University Innsbruck, A6020 Innsbruck, Austria
| | - Thomas Kaufmann
- Institute of Pharmacology, University of Bern, Inselspital, CH3010 Bern, Switzerland
| | - Andreas Villunger
- Division of Developmental Immunology, Biocenter, Medical University Innsbruck, A6020 Innsbruck, Austria.,Tyrolean Cancer Research Institute, A6020 Innsbruck, Austria
| |
Collapse
|
4
|
Gounko NV, Martens E, Opdenakker G, Rybakin V. Thymocyte development in the absence of matrix metalloproteinase-9/gelatinase B. Sci Rep 2016; 6:29852. [PMID: 27432536 PMCID: PMC4949482 DOI: 10.1038/srep29852] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 06/24/2016] [Indexed: 12/13/2022] Open
Abstract
Matrix metalloproteinases (MMP) play critical roles in a variety of immune reactions by facilitating cell migration, and affect cell communication by processing both cytokines and cell surface receptors. Based on published data indicating that MMP-9 is upregulated upon T cell activation and also in the thymus upon the induction of negative selection, we investigated the contribution of MMP-9 into mouse T cell development and differentiation in the thymus. Our data suggest that MMP-9 deficiency does not result in major abnormalities in the development of any conventionally selected or agonist selected subsets and does not interfere with thymocyte apoptosis and clearance, and that MMP-9 expression is not induced in immature T cells at any stage of their thymic development.
Collapse
Affiliation(s)
- Natalia V Gounko
- Laboratory of Immunobiology, REGA Institute, Department of Microbiology and Immunology, KU Leuven, Minderbroedersstraat 10, Leuven 3000, Belgium.,Electron Microscopy Platform, Center for the Biology of Disease VIB and Center for Human Genetics KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Erik Martens
- Laboratory of Immunobiology, REGA Institute, Department of Microbiology and Immunology, KU Leuven, Minderbroedersstraat 10, Leuven 3000, Belgium
| | - Ghislain Opdenakker
- Laboratory of Immunobiology, REGA Institute, Department of Microbiology and Immunology, KU Leuven, Minderbroedersstraat 10, Leuven 3000, Belgium
| | - Vasily Rybakin
- Laboratory of Immunobiology, REGA Institute, Department of Microbiology and Immunology, KU Leuven, Minderbroedersstraat 10, Leuven 3000, Belgium
| |
Collapse
|
5
|
Late stages of T cell maturation in the thymus involve NF-κB and tonic type I interferon signaling. Nat Immunol 2016; 17:565-73. [PMID: 27043411 PMCID: PMC4837029 DOI: 10.1038/ni.3419] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 02/19/2016] [Indexed: 12/11/2022]
Abstract
Positive selection occurs in the thymic cortex, but critical maturation events occur later in the medulla. Here we defined the precise stage at which T cells acquired competence to proliferate and emigrate. Transcriptome analysis of late gene changes suggested roles for the transcription factor NF-κB and interferon signaling. Mice lacking the inhibitor of NF-κB (IκB) kinase (IKK) kinase TAK1 underwent normal positive selection but exhibited a specific block in functional maturation. NF-κB signaling provided protection from death mediated by the cytokine TNF and was required for proliferation and emigration. The interferon signature was independent of NF-κB; however, thymocytes deficient in the interferon-α (IFN-α) receptor IFN-αR showed reduced expression of the transcription factor STAT1 and phenotypic abnormality but were able to proliferate. Thus, both NF-κB and tonic interferon signals are involved in the final maturation of thymocytes into naive T cells.
Collapse
|
6
|
Gabriel SS, Bon N, Chen J, Wekerle T, Bushell A, Fehr T, Cippà PE. Distinctive Expression of Bcl-2 Factors in Regulatory T Cells Determines a Pharmacological Target to Induce Immunological Tolerance. Front Immunol 2016; 7:73. [PMID: 26973650 PMCID: PMC4771729 DOI: 10.3389/fimmu.2016.00073] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 02/15/2016] [Indexed: 12/02/2022] Open
Abstract
Distinctive molecular characteristics of functionally diverse lymphocyte populations may represent novel pharmacological targets for immunotherapy. The intrinsic apoptosis pathway is differently regulated among conventional and regulatory T cells (Tregs). Targeted pharmacological modulation of this pathway with a small molecule Bcl-2/Bcl-xL inhibitor (ABT-737) caused a selective depletion of effector T cells and a relative enrichment of Tregs in vivo. Treatment with ABT-737 resulted in a tolerogenic milieu, which was exploited to alleviate graft-versus-host disease, to prevent allograft rejection in a stringent fully MHC-mismatched skin transplantation model and to induce immunological tolerance in combination with bone marrow transplantation. This concept has the potential to find various applications for immunotherapy, since it allows pharmacologic exploitation of the immunomodulatory properties of Tregs without the need for cell manipulation ex vivo.
Collapse
Affiliation(s)
- Sarah Sharon Gabriel
- Nephrology, Institute of Physiology, University of Zürich, Zürich, Switzerland; Division of Nephrology, University Hospital Zürich, Zürich, Switzerland
| | - Nina Bon
- Nephrology, Institute of Physiology, University of Zürich, Zürich, Switzerland; Division of Nephrology, University Hospital Zürich, Zürich, Switzerland
| | - Jin Chen
- Nephrology, Institute of Physiology, University of Zürich, Zürich, Switzerland; Division of Nephrology, University Hospital Zürich, Zürich, Switzerland
| | - Thomas Wekerle
- Transplantation Immunology, Department of Surgery, Medical University of Vienna , Vienna , Austria
| | - Andrew Bushell
- Transplantation Research Immunology Group, Nuffield Department of Surgical Sciences, University of Oxford , Oxford , UK
| | - Thomas Fehr
- Nephrology, Institute of Physiology, University of Zürich, Zürich, Switzerland; Division of Nephrology, University Hospital Zürich, Zürich, Switzerland; Department of Internal Medicine, Cantonal Hospital Graubünden, Chur, Switzerland
| | | |
Collapse
|
7
|
Sionov RV, Vlahopoulos SA, Granot Z. Regulation of Bim in Health and Disease. Oncotarget 2015; 6:23058-134. [PMID: 26405162 PMCID: PMC4695108 DOI: 10.18632/oncotarget.5492] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 08/08/2015] [Indexed: 11/25/2022] Open
Abstract
The BH3-only Bim protein is a major determinant for initiating the intrinsic apoptotic pathway under both physiological and pathophysiological conditions. Tight regulation of its expression and activity at the transcriptional, translational and post-translational levels together with the induction of alternatively spliced isoforms with different pro-apoptotic potential, ensure timely activation of Bim. Under physiological conditions, Bim is essential for shaping immune responses where its absence promotes autoimmunity, while too early Bim induction eliminates cytotoxic T cells prematurely, resulting in chronic inflammation and tumor progression. Enhanced Bim induction in neurons causes neurodegenerative disorders including Alzheimer's, Parkinson's and Huntington's diseases. Moreover, type I diabetes is promoted by genetically predisposed elevation of Bim in β-cells. On the contrary, cancer cells have developed mechanisms that suppress Bim expression necessary for tumor progression and metastasis. This review focuses on the intricate network regulating Bim activity and its involvement in physiological and pathophysiological processes.
Collapse
Affiliation(s)
- Ronit Vogt Sionov
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel Canada, Hebrew University, Hadassah Medical School, Jerusalem, Israel
| | - Spiros A. Vlahopoulos
- First Department of Pediatrics, University of Athens, Horemeio Research Laboratory, Thivon and Levadias, Goudi, Athens, Greece
| | - Zvi Granot
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel Canada, Hebrew University, Hadassah Medical School, Jerusalem, Israel
| |
Collapse
|
8
|
CBAP promotes thymocyte negative selection by facilitating T-cell receptor proximal signaling. Cell Death Dis 2014; 5:e1518. [PMID: 25393474 PMCID: PMC4260732 DOI: 10.1038/cddis.2014.474] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 08/29/2014] [Accepted: 10/06/2014] [Indexed: 12/11/2022]
Abstract
T-cell receptor (TCR)-transduced signaling is critical to thymocyte development at the CD4/CD8 double-positive stage, but the molecules involved in this process are not yet fully characterized. We previously demonstrated that GM-CSF/IL-3/IL-5 receptor common β-chain-associated protein (CBAP) modulates ZAP70-mediated T-cell migration and adhesion. On the basis of the high expression of CBAP during thymocyte development, we investigated the function of CBAP in thymocyte development using a CBAP knockout mouse. CBAP-deficient mice showed normal early thymocyte development and positive selection. In contrast, several negative selection models (including TCR transgene, superantigen staphylococcal enterotoxin B, and anti-CD3 antibody treatment) revealed an attenuation of TCR-induced thymocyte deletion in CBAP knockout mice. This phenotype correlated with a reduced accumulation of BIM upon TCR crosslinking in CBAP-deficient thymocytes. Loss of CBAP led to reduced TCR-induced phosphorylation of proteins involved in both proximal and distal signaling events, including ZAP70, LAT, PLCγ1, and JNK1/2. Moreover, TCR-induced association of LAT signalosome components was reduced in CBAP-deficient thymocytes. Our data demonstrate that CBAP is a novel component in the TCR signaling pathway and modulates thymocyte apoptosis during negative selection.
Collapse
|
9
|
Rupp LJ, Brady BL, Carpenter AC, De Obaldia ME, Bhandoola A, Bosselut R, Muljo SA, Bassing CH. The microRNA biogenesis machinery modulates lineage commitment during αβ T cell development. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2014; 193:4032-42. [PMID: 25217159 PMCID: PMC4185242 DOI: 10.4049/jimmunol.1401359] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Differentiation of CD4(+) helper and CD8(+) cytotoxic αβ T cells from CD4(+)CD8(+) thymocytes involves upregulation of lineage-specifying transcription factors and transcriptional silencing of CD8 or CD4 coreceptors, respectively, in MHC class II or I (MHCII or I)-restricted thymocytes. In this study, we demonstrate that inactivation of the Dicer RNA endonuclease in murine thymocytes impairs initiation of Cd4 and Cd8 silencing, leading to development of positively selected MHCI- and MHCII-restricted mature CD4(+)CD8(+) thymocytes. Expression of the antiapoptotic BCL2 protein or inactivation of the p53 proapoptotic protein rescues these thymocytes from apoptosis, increasing their frequency and permitting accumulation of CD4(+)CD8(+) αβ T cells in the periphery. Dicer-deficient MHCI-restricted αβ T cells fail to normally silence Cd4 and display impaired induction of the CD8 lineage-specifying transcription factor Runx3, whereas Dicer-deficient MHCII-restricted αβ T cells show impaired Cd8 silencing and impaired induction of the CD4 lineage-specifying transcription factor Thpok. Finally, we show that the Drosha RNA endonuclease, which functions upstream of Dicer in microRNA biogenesis, also regulates Cd4 and Cd8 silencing. Our data demonstrate a previously dismissed function for the microRNA biogenesis machinery in regulating expression of lineage-specifying transcription factors and silencing of Cd4 and Cd8 during αβ T cell differentiation.
Collapse
Affiliation(s)
- Levi J Rupp
- Division of Cancer Pathobiology, Department of Pathology and Laboratory Medicine, Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, PA 19104; Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104; Cell and Molecular Biology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Brenna L Brady
- Division of Cancer Pathobiology, Department of Pathology and Laboratory Medicine, Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, PA 19104; Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104; Integrative Immunobiology Unit, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Andrea C Carpenter
- Laboratory of Immune Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892; and
| | - Maria Elena De Obaldia
- Immunology Graduate Group, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Avinash Bhandoola
- Immunology Graduate Group, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Remy Bosselut
- Laboratory of Immune Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892; and
| | - Stefan A Muljo
- Integrative Immunobiology Unit, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Craig H Bassing
- Division of Cancer Pathobiology, Department of Pathology and Laboratory Medicine, Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, PA 19104; Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104; Cell and Molecular Biology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104; Immunology Graduate Group, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| |
Collapse
|
10
|
N-glycosylation bidirectionally extends the boundaries of thymocyte positive selection by decoupling Lck from Ca²⁺ signaling. Nat Immunol 2014; 15:1038-45. [PMID: 25263124 DOI: 10.1038/ni.3007] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Accepted: 09/09/2014] [Indexed: 12/13/2022]
Abstract
Positive selection of diverse yet self-tolerant thymocytes is vital to immunity and requires a limited degree of T cell antigen receptor (TCR) signaling in response to self peptide-major histocompatibility complexes (self peptide-MHCs). Affinity of newly generated TCR for peptide-MHC primarily sets the boundaries for positive selection. We report that N-glycan branching of TCR and the CD4 and CD8 coreceptors separately altered the upper and lower affinity boundaries from which interactions between peptide-MHC and TCR positively select T cells. During thymocyte development, N-glycan branching varied approximately 15-fold. N-glycan branching was required for positive selection and decoupled Lck signaling from TCR-driven Ca(2+) flux to simultaneously promote low-affinity peptide-MHC responses while inhibiting high-affinity ones. Therefore, N-glycan branching imposes a sliding scale on interactions between peptide-MHC and TCR that bidirectionally expands the affinity range for positive selection.
Collapse
|
11
|
A regulatory role for TGF-β signaling in the establishment and function of the thymic medulla. Nat Immunol 2014; 15:554-61. [DOI: 10.1038/ni.2869] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 03/11/2014] [Indexed: 12/16/2022]
|
12
|
Targeting the mitochondrial apoptotic pathway: a preferred approach in hematologic malignancies? Cell Death Dis 2014; 5:e1098. [PMID: 24603326 PMCID: PMC3973243 DOI: 10.1038/cddis.2014.61] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 01/23/2014] [Accepted: 01/24/2014] [Indexed: 02/05/2023]
Abstract
Acquired resistance toward apoptosis represents one of the hallmarks of human cancer and a major cause of the inefficacy of most anticancer treatment regimens. Based on its ability to inhibit apoptosis, the B-cell lymphoma/leukemia 2 (Bcl-2) protein family has garnered the most attention as a promising therapeutic target in cancer. Accordingly, efforts have lately been focused on the development of drugs targeting Bcl-2 proteins with considerable therapeutic success, particularly in hematologic malignancies. Here, we review the previous studies and highlight the pivotal role of the Bcl-2 protein family in the homeostasis of hematologic tissue compartment. This knowledge provides more insight into why some cancers are more sensitive to Bcl-2 targeting than others and will foster the clinical evaluation of Bcl-2-targeting strategies in cancer by avoiding severe on-target side effects in the development of healthy tissues.
Collapse
|
13
|
Gray DHD, Kupresanin F, Berzins SP, Herold MJ, O'Reilly LA, Bouillet P, Strasser A. The BH3-only proteins Bim and Puma cooperate to impose deletional tolerance of organ-specific antigens. Immunity 2012; 37:451-62. [PMID: 22960223 DOI: 10.1016/j.immuni.2012.05.030] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 05/14/2012] [Accepted: 05/31/2012] [Indexed: 11/25/2022]
Abstract
Although the proapoptotic BH3-only protein, Bim, is required for deletion of autoreactive thymocytes, Bim-deficient mice do not succumb to extensive organ-specific autoimmune disease. To determine whether other BH3-only proteins safeguard tolerance in the absence of Bim, we screened mice lacking Bim as well as other BH3-only proteins. Most strains showed no additional defects; however, mice deficient for both Puma and Bim spontaneously developed autoimmunity in multiple organs, and their T cells could transfer organ-specific autoimmunity. Puma- and Bim-double-deficient mice had a striking accumulation of mature, single-positive thymocytes, suggesting an additional defect in thymic deletion was the basis for disease. Transgenic mouse models of thymocyte deletion by peripheral neoantigens confirmed that the loss of Bim and Puma allowed increased numbers of autoreactive thymocytes to escape deletion. Our data show that Puma cooperates with Bim to impose a thymic-deletion checkpoint to peripheral self-antigens and cement the notion that defects in apoptosis alone are sufficient to cause autoimmune disease.
Collapse
Affiliation(s)
- Daniel H D Gray
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia.
| | | | | | | | | | | | | |
Collapse
|
14
|
Elevated Mcl-1 inhibits thymocyte apoptosis and alters thymic selection. Cell Death Differ 2012; 19:1962-71. [PMID: 22743995 DOI: 10.1038/cdd.2012.84] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
T cells developing in the thymus undergo rigorous positive and negative selection to ensure that those exported to peripheral lymphoid organs bear T-cell receptors (TCRs) capable of reacting with foreign antigens but tolerant of self. At each checkpoint, whether a thymocyte survives or dies is determined by antiapoptotic and proapoptotic Bcl-2 family members. We used Mcl-1 transgenic (tg) mice to investigate the impact of elevated expression of antiapoptotic Mcl-1 on thymocyte apoptosis and selection, making a side-by-side comparison with thymocytes from BCL-2tg mice. Mcl-1 was as effective as Bcl-2 at protecting thymocytes against spontaneous cell death, diverse cytotoxic insults and TCR-CD3 stimulation-driven apoptosis. In three different TCR tg models, Mcl-1 markedly enhanced positive selection of thymocytes, as did Bcl-2. In H-Y TCR tg mice, elevated Mcl-1 and Bcl-2 were equally effective at inhibiting deletion of autoreactive thymocytes. However, in the OT-1tg model where deletion is mediated by a peripheral antigen whose expression is regulated by Aire, Mcl-1 was less effective than Bcl-2. Thus, the capacity of Mcl-1 overexpression to inhibit apoptosis triggered by TCR stimulation apparently depends on the thymocyte subset subject to deletion, presumably due to differences in the profiles of proapoptotic Bcl-2 family members mediating the deletion.
Collapse
|
15
|
Abstract
Somatic recombination of TCR genes in immature thymocytes results in some cells with useful TCR specificities, but also many with useless or potentially self-reactive specificities. Thus thymic selection mechanisms operate to shape the T-cell repertoire. Thymocytes that have a TCR with low affinity for self-peptide-MHC complexes are positively selected to further differentiate and function in adaptive immunity, whereas useless ones die by neglect. Clonal deletion and clonal diversion (Treg differentiation) are the major processes in the thymus that eliminate or control self-reactive T cells. Although these processes are thought to be efficient, they fail to control self-reactivity in all circumstances. Thus, peripheral tolerance processes exist wherein self-reactive T cells become functionally unresponsive (anergy) or are deleted after encountering self-antigens outside of the thymus. Recent advances in mechanistic studies of central and peripheral T-cell tolerance are promoting the development of therapeutic strategies to treat autoimmune disease and cancer and improve transplantation outcome.
Collapse
Affiliation(s)
- Yan Xing
- Center for Immunology, Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, 55455, USA
| | | |
Collapse
|
16
|
Abstract
During the development and normal function of T lymphocytes, the cells are subject to several checkpoints at which they must "decide" to live or die. At these critical times and during homeostasis, the molecules that regulate the classical apoptotic pathways and survival pathways such as autophagy have critical roles in controlling this decision. Our laboratory has focused on the roles of apoptotic and autophagic proteins in T lymphocyte development and function. Using genetic models in mice and in vitro analyses of T cell functions, we have outlined critical roles for the Bcl-2 family (regulators of the intrinsic pathway of apoptosis), c-FLIP (an anti-apoptotic protein in the extrinsic pathway of apoptosis), and autophagy in T lymphocytes.
Collapse
|
17
|
Morrot A, Terra-Granado E, Pérez AR, Silva-Barbosa SD, Milićević NM, Farias-de-Oliveira DA, Berbert LR, De Meis J, Takiya CM, Beloscar J, Wang X, Kont V, Peterson P, Bottasso O, Savino W. Chagasic thymic atrophy does not affect negative selection but results in the export of activated CD4+CD8+ T cells in severe forms of human disease. PLoS Negl Trop Dis 2011; 5:e1268. [PMID: 21858238 PMCID: PMC3156684 DOI: 10.1371/journal.pntd.0001268] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 06/21/2011] [Indexed: 11/19/2022] Open
Abstract
Extrathymic CD4+CD8+ double-positive (DP) T cells are increased in some pathophysiological conditions, including infectious diseases. In the murine model of Chagas disease, it has been shown that the protozoan parasite Trypanosoma cruzi is able to target the thymus and induce alterations of the thymic microenvironment and the lymphoid compartment. In the acute phase, this results in a severe atrophy of the organ and early release of DP cells into the periphery. To date, the effect of the changes promoted by the parasite infection on thymic central tolerance has remained elusive. Herein we show that the intrathymic key elements that are necessary to promote the negative selection of thymocytes undergoing maturation during the thymopoiesis remains functional during the acute chagasic thymic atrophy. Intrathymic expression of the autoimmune regulator factor (Aire) and tissue-restricted antigen (TRA) genes is normal. In addition, the expression of the proapoptotic Bim protein in thymocytes was not changed, revealing that the parasite infection-induced thymus atrophy has no effect on these marker genes necessary to promote clonal deletion of T cells. In a chicken egg ovalbumin (OVA)-specific T-cell receptor (TCR) transgenic system, the administration of OVA peptide into infected mice with thymic atrophy promoted OVA-specific thymocyte apoptosis, further indicating normal negative selection process during the infection. Yet, although the intrathymic checkpoints necessary for thymic negative selection are present in the acute phase of Chagas disease, we found that the DP cells released into the periphery acquire an activated phenotype similar to what is described for activated effector or memory single-positive T cells. Most interestingly, we also demonstrate that increased percentages of peripheral blood subset of DP cells exhibiting an activated HLA-DR+ phenotype are associated with severe cardiac forms of human chronic Chagas disease. These cells may contribute to the immunopathological events seen in the Chagas disease. The thymus is a primary lymphoid organ that plays an important role on the development of the immune system and maturation of the T cell repertoire. During the normal life span, this organ undergoes involution during the aging and also in the presence of a wide variety of infectious diseases. It has been shown that the protozoan parasite Trypanosoma cruzi is able to target the thymus and induce alterations of the thymic microenvironment. In the acute phase, this results in a severe atrophy of the organ and early release of immature double-positive (DP) T cells into the periphery. The effect of the changes promoted by the parasite infection on thymic central tolerance has remained not clear. The present study shows that the intrathymic key elements that promote the negative selection of thymocytes during the thymopoiesis remains functional in the acute chagasic thymic atrophy. However, we found that the DP cells released into the periphery acquire an activated phenotype and its high frequency in the peripheral blood are associated with severe cardiac forms of human chronic Chagas disease.
Collapse
Affiliation(s)
- Alexandre Morrot
- Department of Immunology, Microbiology Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Zhan Y, Zhang Y, Gray D, Carrington EM, Bouillet P, Ko HJ, O’Reilly L, Wicks IP, Strasser A, Lew AM. Defects in the Bcl-2-regulated apoptotic pathway lead to preferential increase of CD25 low Foxp3+ anergic CD4+ T cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2011; 187:1566-77. [PMID: 21742968 PMCID: PMC3150360 DOI: 10.4049/jimmunol.1100027] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Defects in the Bcl-2-regulated apoptotic pathway inhibit the deletion of self-reactive T cells. What is unresolved, however, is the nature and fate of such self-reactive T cells escaping deletion. In this study, we report that mice with such defects contained increased numbers of CD25(low)Foxp3(+) cells in the thymus and peripheral lymph tissues. The increased CD25(low)Foxp3(+) population contained a large fraction of cells bearing self-reactive TCRs, evident from a prominent increase in self-superantigen-specific Foxp3(+)Vβ5(+)CD4(+) T cells in BALB/c Bim(-/-) mice compared with control animals. The survival rate of the expanded CD25(low)Foxp3(+) cells was similar to that of CD25(high)Foxp3(+) CD4 T cells in vitro and in vivo. IL-2R stimulation, but not TCR ligation, upregulated CD25 on CD25(low)Foxp3(+)CD4(+) T cells in vitro and in vivo. The expanded CD25(low)Foxp3(+)CD4(+) T cells from Bim(-/-) mice were anergic but also had weaker regulatory function than CD25(high)Foxp3(+) CD4(+) T cells from the same mice. Analysis of Bim(-/-) mice that also lacked Fas showed that the peripheral homeostasis of this expanded population was in part regulated by this death receptor. In conclusion, these results show that self-reactive T cell escapes from thymic deletion in mice defective in the Bcl-2-regulated apoptotic pathway upregulate Foxp3 and become unresponsive upon encountering self-Ag without necessarily gaining potent regulatory function. This clonal functional diversion may help to curtail autoaggressiveness of escaped self-reactive CD4(+) T cells and thereby safeguard immunological tolerance.
Collapse
Affiliation(s)
- Yifan Zhan
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Yuxia Zhang
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Daniel Gray
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Emma M Carrington
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Philippe Bouillet
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Hyun-Ja Ko
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Lorraine O’Reilly
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Ian P Wicks
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Andreas Strasser
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Andrew M Lew
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| |
Collapse
|
19
|
Takada K, Wang X, Hart GT, Odumade OA, Weinreich MA, Hogquist KA, Jameson SC. Kruppel-like factor 2 is required for trafficking but not quiescence in postactivated T cells. THE JOURNAL OF IMMUNOLOGY 2010; 186:775-83. [PMID: 21160050 DOI: 10.4049/jimmunol.1000094] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The transcription factor Kruppel-like factor 2 (KLF2) was proposed to regulate genes involved in cell cycle entry and T cell trafficking; however, the physiological role of its expression in postactivated T cells is not well defined. Previous studies suggested that the cytokines IL-2 and IL-15 differentially regulate KLF2 re-expression in postactivation T cells and that these cytokines also influence effector versus memory T cell differentiation. Using conditional and inducible KLF2-knockout model systems, we tested the specific role of KLF2 expression in activated CD8(+) T cells cultured with these cytokines. KLF2 was required for effective transcription of sphingosine-1-phosphate receptor-1 (S1P(1)) and CD62L in postactivation T cells. However, although different cytokines dramatically altered the expression of cell-cycle-related genes, endogenous KLF2 had a minimal impact. Correspondingly, KLF2-deficient T cells showed dysregulated trafficking but not altered proliferative characteristics following in vivo responses to Ag. Thus, our data help to define KLF2-dependent and -independent aspects of activated CD8(+) T cell differentiation and argue against a physiological role in cell cycle regulation.
Collapse
Affiliation(s)
- Kensuke Takada
- Department of Laboratory Medicine and Pathology, Center for Immunology, University of Minnesota, Minneapolis, MN 55414, USA.
| | | | | | | | | | | | | |
Collapse
|
20
|
Wiegers GJ, Kaufmann M, Tischner D, Villunger A. Shaping the T‐cell repertoire: a matter of life and death. Immunol Cell Biol 2010; 89:33-9. [DOI: 10.1038/icb.2010.127] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- G Jan Wiegers
- Division of Developmental Immunology, Biocenter, Medical University Innsbruck Innsbruck Austria
| | - Manuel Kaufmann
- Division of Developmental Immunology, Biocenter, Medical University Innsbruck Innsbruck Austria
| | - Denise Tischner
- Division of Developmental Immunology, Biocenter, Medical University Innsbruck Innsbruck Austria
| | - Andreas Villunger
- Division of Developmental Immunology, Biocenter, Medical University Innsbruck Innsbruck Austria
| |
Collapse
|
21
|
Abstract
Cell death mediated through the intrinsic, Bcl-2-regulated mitochondrial apoptosis signalling pathway is critical for lymphocyte development and the establishment of central and maintenance of peripheral tolerance. Defects in Bcl-2-regulated cell death signalling have been reported to cause or correlate with autoimmunity in mice and men. This review focuses on the role of Bcl-2 family proteins implicated in the development of autoimmune disorders and their potential as targets for therapeutic intervention.
Collapse
|
22
|
Hu Q, Sader A, Parkman JC, Baldwin TA. Bim-mediated apoptosis is not necessary for thymic negative selection to ubiquitous self-antigens. THE JOURNAL OF IMMUNOLOGY 2010; 183:7761-7. [PMID: 19933852 DOI: 10.4049/jimmunol.0902181] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
T cell education in the thymus is critical for establishing a functional, yet self-tolerant, T cell repertoire. Negative selection is a key process in enforcing self-tolerance. There are many questions that surround the mechanism of negative selection, but it is currently held that apoptosis initiated by Bim and/or Nur77 is critical for negative selection. Recent studies, however, have questioned the necessity of Bim in maintaining both central and peripheral T cell tolerance. To reconcile these apparently contradictory findings, we examined the role of Bim in negative selection in the well-characterized, physiological HY(cd4) mouse model. We found that while Bim expression was required for CD4(+)CD8(+) double-positive thymocyte apoptosis, it was not required for negative selection. Furthermore, Bim deficiency did not alter the frequency or affinity of male reactive cells that escape negative selection in an oligoclonal repertoire. Collectively, these studies indicate that negative selection occurs efficiently in the absence of apoptosis and suggest that the current paradigm of negative selection requiring apoptosis be revisited.
Collapse
Affiliation(s)
- Qian Hu
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | | | | | | |
Collapse
|
23
|
Hutcheson J, Perlman H. BH3-only proteins in rheumatoid arthritis: potential targets for therapeutic intervention. Oncogene 2009; 27 Suppl 1:S168-75. [PMID: 19641502 DOI: 10.1038/onc.2009.54] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Rheumatoid arthritis (RA) is a debilitating disease, resulting in the destruction of bone and cartilage, and in the permanent disfigurement of joints. Although the precise cause of RA is currently unresolved, it has become clear that the damaging effects are a result of the toxic milieu caused by an influx of inflammatory cells and the resulting heightened proinflammatory state within the joint. As the amount of literature suggesting that this preponderance of cells is a result of decreased local apoptosis in the joint continues to increase, in this review, we describe how Bcl-2 family pro-apoptotic BH3-only proteins, particularly Bim and Bid, could act to protect against the development of the disease. We also suggest a role for BH3-mimetic drugs as potential therapeutics in the treatment of RA.
Collapse
Affiliation(s)
- J Hutcheson
- Rheumatic Diseases Division, Department of Internal Medicine, University of Texas - Southwestern Medical Center, Simmons Arthritis Research Center, Dallas, TX, USA
| | | |
Collapse
|
24
|
Kovalovsky D, Yu Y, Dose M, Emmanouilidou A, Konstantinou T, Germar K, Aghajani K, Guo Z, Mandal M, Gounari F. Beta-catenin/Tcf determines the outcome of thymic selection in response to alphabetaTCR signaling. THE JOURNAL OF IMMUNOLOGY 2009; 183:3873-84. [PMID: 19717519 DOI: 10.4049/jimmunol.0901369] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Thymic maturation of T cells depends on the intracellular interpretation of alphabetaTCR signals by processes that are poorly understood. In this study, we report that beta-catenin/Tcf signaling was activated in double-positive thymocytes in response to alphabetaTCR engagement and impacted thymocyte selection. TCR engagement combined with activation of beta-catenin signaled thymocyte deletion, whereas Tcf-1 deficiency rescued from negative selection. Survival/apoptotis mediators including Bim, Bcl-2, and Bcl-x(L) were alternatively influenced by stabilization of beta-catenin or ablation of Tcf-1, and Bim-mediated beta-catenin induced thymocyte deletion. TCR activation in double-positive cells with stabilized beta-catenin triggered signaling associated with negative selection, including sustained overactivation of Lat and Jnk and a transient activation of Erk. These observations are consistent with beta-catenin/Tcf signaling acting as a switch that determines the outcome of thymic selection downstream the alphabetaTCR cascade.
Collapse
Affiliation(s)
- Damian Kovalovsky
- Molecular Oncology Research Institute, Tufts New England Medical Center, Boston, MA 02111, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Yang CY, Lin NH, Lee JM, Huang CY, Min HJ, Yen JJY, Liao NS, Yang-Yen HF. Promoter knock-in mutations reveal a role of Mcl-1 in thymocyte-positive selection and tissue or cell lineage-specific regulation of Mcl-1 expression. THE JOURNAL OF IMMUNOLOGY 2009; 182:2959-68. [PMID: 19234191 DOI: 10.4049/jimmunol.0803550] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We previously demonstrated that IL-3 stimulates transcription of the antiapoptotic gene mcl-1 via two promoter elements designated as the SIE and CRE-2 sites. To further study the functional role of these two DNA elements, mutant mice with targeted mutations of both SIE and CRE-2 sites (SC mutants) were generated. Homozygous SC mutants manifested a markedly reduced level of Mcl-1 in thymus but not in other major organs such as spleen, liver, lung, or heart. Reduced expression of Mcl-1 in SC mutant thymus resulted in attenuated positive selection of double-positive thymocytes into both CD4 and CD8 lineages, a result likely due to reduced survival of SC mutant double-positive thymocytes that were supposed to be positively selected. In contrast, in the peripheral lymphoid organs, only CD8(+) but not CD4(+) T cells were significantly reduced in homozygous SC mutant mice, a result consistent with a more dramatic decrease both of Mcl-1 expression and cell viability in mutant CD8(+) compared with mutant CD4(+) T cells. Impaired T cell development and peripheral CD8(+) lymphopenia in homozygous SC mutant mice were both cell autonomous and could be rescued by enforced expression of human Mcl-1. Together, the promoter-knock-in mouse model generated in this study not only revealed a role of Mcl-1 in thymocyte-positive selection, but also uncovered that Mcl-1 expression is regulated in a tissue or cell lineage-specific manner.
Collapse
Affiliation(s)
- Chia-Yu Yang
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
| | | | | | | | | | | | | | | |
Collapse
|
26
|
Clybouw C, Hadji A, ElMchichi B, Auffredou MT, Leca G, Vazquez A. BimL upregulation induced by BCR cross-linking in BL41 Burkitt's lymphoma results from a splicing mechanism of the BimEL mRNA. Biochem Biophys Res Commun 2009; 383:32-6. [PMID: 19332026 DOI: 10.1016/j.bbrc.2009.03.123] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Accepted: 03/20/2009] [Indexed: 11/25/2022]
Abstract
B lymphocyte receptor-mediated apoptosis is associated with increased expression of the BimL isoform of Bim. The mechanisms involved in the regulation of BimL protein expression are still unknown. We report that BimL expression following BCR activation is not associated with a specific increase of BimL mRNA but rather to the intron retention structure of the BimEL mRNA. Indeed, expression of a BimEL cDNA leads in Hela cells leads to the production of both BimEL and BimL proteins. Mutation of the intron-splicing GT sequence present in the exon 3 results in the production of only BimEL protein. Ectopic expression of BimEL cDNA resulted in a large increase of BimL expression upon BCR-stimulation, whereas cells transfected with the GT/AA mutated form of BimEL only produced BimEL proteins upon BCR-activation. These data showed that BimL expression induced by BCR activation may result from the splicing of BimEL mRNA independently of Bim promoter regulation.
Collapse
Affiliation(s)
- Cyril Clybouw
- INSERM U., Université Paris-Sud, Hôpital Paul Brousse, Villejuif, France
| | | | | | | | | | | |
Collapse
|
27
|
Abstract
FAS belongs to the subgroup of the tumor necrosis factor receptor (TNF-R) family that contains an intracellular "death domain" and triggers apoptosis. Its physiological ligand FASL is a member of the TNF cytokine family. Studies with mutant mice and cells from human patients have shown that FAS plays critical roles in the immune system, including the killing of pathogen-infected cells and the death of obsolete and potentially dangerous lymphocytes. Fas thereby functions as a guardian against autoimmunity and tumor development. FAS triggers apoptosis through FADD-mediated recruitment and activation of caspase-8. In certain cells such as hepatocytes, albeit not lymphocytes, FAS-induced apoptosis requires amplification through proteolytic activation of the proapoptotic BCL-2 family member BID. Curiously, several components of the FAS signaling machinery have been implicated in nonapoptotic processes, including cellular activation, differentiation, and proliferation. This review describes current understanding of Fas-induced apoptosis signaling and proposes experimental strategies for future advances.
Collapse
Affiliation(s)
- Andreas Strasser
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.
| | | | | |
Collapse
|
28
|
Abstract
The elimination of unwanted cells by programmed cell death is a common feature of animal development. Genetic studies in the nematode Caenorhabditis elegans, the fruit fly Drosophila melanogaster, and the mouse have not only revealed the molecular machineries that cause the programmed demise of specific cells, but have also allowed us to get a glimpse of the types of pathways that regulate these machineries during development. Rather than serving as a broad overview of programmed cell death during development, this review focuses on recent advances in our understanding of the regulation of specific programmed cell death events during nematode, fly, and mouse development. Recent studies have revealed that many of the regulatory pathways involved play additional important roles in development, which confirms that the programmed cell death fate is an integral aspect of animal development.
Collapse
Affiliation(s)
- Barbara Conradt
- Department of Genetics, Norris Cotton Cancer Center, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
| |
Collapse
|
29
|
Abstract
Lymphocyte homeostasis is tightly regulated in vivo by various factors including cytokines, antigens, and costimulatory signals. Central to this regulation is the intricate balance between survival and apoptosis determined by pro- and antiapoptotic factors, including Bcl-2/Bcl-xL of the Bcl-2 family in the intrinsic death pathway and Fas/FADD of the TNF death receptor superfamily in the extrinsic death pathway. Recent studies have identified a critical role for autophagy, a well-conserved catabolic process in eukaryotic cells, in T and B lymphocyte homeostasis. Autophagy is essential for mature T lymphocyte survival and proliferation. In addition, autophagy can promote T cell death in defined physiologic or pathologic conditions. Autophagy also contributes to the survival of subsets of B lymphocytes, including developing pre-B cells as well as B1 B cells in vivo. Thus, autophagy represents a novel pathway regulating both developing and mature lymphocytes. Future studies are required to investigate the role of autophagy in regulating T and B cell homeostasis during immune responses to pathogens, as well as to define the mechanisms by which autophagy regulates lymphocyte death and survival.
Collapse
|
30
|
Barron L, Knoechel B, Lohr J, Abbas AK. Cutting edge: contributions of apoptosis and anergy to systemic T cell tolerance. THE JOURNAL OF IMMUNOLOGY 2008; 180:2762-6. [PMID: 18292495 DOI: 10.4049/jimmunol.180.5.2762] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Multiple pathways can induce and maintain peripheral T cell tolerance. The goal of this study was to define the contributions of apoptosis and anergy to the maintenance of self-tolerance to a systemic Ag. Upon transfer into mice expressing OVA systemically, OVA-specific DO11 CD4+ T cells are activated transiently, cease responding, and die. Bim is the essential apoptosis-inducing trigger and apoptosis proceeds despite increased expression of Bcl-2 and Bcl-x. However, preventing apoptosis by eliminating Bim does not restore proliferation or cytokine production by DO11 cells. While Foxp3 is transiently induced, anergy is not associated with the stable development of regulatory T cells. Thus, apoptosis is dispensable for tolerance to a systemic self-Ag and cell-intrinsic anergy is sufficient to tolerize T cells.
Collapse
Affiliation(s)
- Luke Barron
- Department of Pathology, University of California, San Francisco, CA 94143, USA
| | | | | | | |
Collapse
|
31
|
Abstract
It has been almost three decades since the term "apoptosis" was first coined to describe a unique form of cell death that involves orderly, gene-dependent cell disintegration. It is now well accepted that apoptosis is an essential life process for metazoan animals and is critical for the formation and function of tissues and organs. In the adult mammalian body, apoptosis is especially important for proper functioning of the immune system. In recent years, along with the rapid advancement of molecular and cellular biology, great progress has been made in understanding the mechanisms leading to apoptosis. It is generally accepted that there are two major pathways of apoptotic cell death induction: extrinsic signaling through death receptors that leads to the formation of the death-inducing signaling complex (DISC), and intrinsic signaling mainly through mitochondria which leads to the formation of the apoptosome. Formation of the DISC or apoptosome, respectively, activates initiator and common effector caspases that execute the apoptosis process. In the immune system, both pathways operate; however, it is not known whether they are sufficient to maintain lymphocyte homeostasis. Recently, new apoptotic mechanisms including caspase-independent pathways and granzyme-initiated pathways have been shown to exist in lymphocytes. This review will summarize our understanding of the mechanisms that control the homeostasis of various lymphocyte populations.
Collapse
Affiliation(s)
- Guangwu Xu
- Department of Molecular Genetics, Microbiology and Immunology, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, NJ 08854, USA
| | | |
Collapse
|
32
|
Labi V, Erlacher M, Kiessling S, Manzl C, Frenzel A, O'Reilly L, Strasser A, Villunger A. Loss of the BH3-only protein Bmf impairs B cell homeostasis and accelerates gamma irradiation-induced thymic lymphoma development. ACTA ACUST UNITED AC 2008; 205:641-55. [PMID: 18299399 PMCID: PMC2275386 DOI: 10.1084/jem.20071658] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Members of the Bcl-2 protein family play crucial roles in the maintenance of tissue homeostasis by regulating apoptosis in response to developmental cues or exogenous stress. Proapoptotic BH3-only members of the Bcl-2 family are essential for initiation of cell death, and they function by activating the proapoptotic Bcl-2 family members Bax and/or Bak, either directly or indirectly through binding to prosurvival Bcl-2 family members. Bax and Bak then elicit the downstream events in apoptosis signaling. Mammals have at least eight BH3-only proteins and they are activated in a stimulus-specific, as well as a cell type–specific, manner. We have generated mice lacking the BH3-only protein Bcl-2–modifying factor (Bmf) to investigate its role in cell death signaling. Our studies reveal that Bmf is dispensable for embryonic development and certain forms of stress-induced apoptosis, including loss of cell attachment (anoikis) or UV irradiation. Remarkably, loss of Bmf protected lymphocytes against apoptosis induced by glucocorticoids or histone deacetylase inhibition. Moreover, bmf−/− mice develop a B cell–restricted lymphadenopathy caused by the abnormal resistance of these cells to a range of apoptotic stimuli. Finally, Bmf-deficiency accelerated the development of γ irradiation–induced thymic lymphomas. Our results demonstrate that Bmf plays a critical role in apoptosis signaling and can function as a tumor suppressor.
Collapse
Affiliation(s)
- Verena Labi
- Division of Developmental Immunology, Biocenter, Innsbruck Medical University, 6020 Innsbruck, Austria
| | | | | | | | | | | | | | | |
Collapse
|
33
|
Hutcheson J, Scatizzi JC, Siddiqui AM, Haines GK, Wu T, Li QZ, Davis LS, Mohan C, Perlman H. Combined Deficiency of Proapoptotic Regulators Bim and Fas Results in the Early Onset of Systemic Autoimmunity. Immunity 2008; 28:206-17. [DOI: 10.1016/j.immuni.2007.12.015] [Citation(s) in RCA: 169] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2007] [Revised: 12/11/2007] [Accepted: 12/14/2007] [Indexed: 01/02/2023]
|
34
|
Cretney E, Uldrich AP, McNab FW, Godfrey DI, Smyth MJ. No requirement for TRAIL in intrathymic negative selection. Int Immunol 2008; 20:267-76. [PMID: 18192669 DOI: 10.1093/intimm/dxm144] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The contribution of the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) pathway to intrathymic negative selection is a controversial subject with two studies suggesting a key role for TRAIL, while others demonstrated normal negative selection, in TRAIL- and TRAIL receptor-deficient mice. The basis of these discrepancies is unclear and may in part reflect differences in the negative selection models under investigation. Considering the importance of the negative selection process in the establishment of a competent immune system, it is essential that these discrepancies be fully resolved. In this study, we failed to identify a role for TRAIL in an acute model of peptide antigen-specific negative selection using a TCR transgenic system as well as antibody-mediated TCR/CD3 ligation in vitro and in vivo. Moreover, thymic dendritic cells, the main cellular mediators of negative selection in the thymus, did not constitutively express TRAIL, and TRAIL receptor (DR5) expression was negative or extremely low on thymocytes. Furthermore, in vitro thymocyte deletion was normal in C57BL/6 TRAIL(-/-) gld mice, suggesting that TRAIL and FasL do not function cooperatively to induce negative selection. These results, combined with the fact that aged C57BL/6 TRAIL(-/-) mice showed no signs of spontaneous autoimmunity, strongly indicate that intrathymic negative selection occurs normally in the absence of TRAIL signaling.
Collapse
Affiliation(s)
- Erika Cretney
- Cancer Immunology Program, Trescowthick Research Laboratories, Peter MacCallum Cancer Centre, East Melbourne, Victoria 3002, Australia
| | | | | | | | | |
Collapse
|
35
|
Davalos-Misslitz ACM, Worbs T, Willenzon S, Bernhardt G, Förster R. Impaired responsiveness to T-cell receptor stimulation and defective negative selection of thymocytes in CCR7-deficient mice. Blood 2007; 110:4351-9. [PMID: 17785582 DOI: 10.1182/blood-2007-01-070284] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The chemokine receptor CCR7 has been implicated in maintenance of thymus morphology and establishment of tolerance to self-antigens. In this study, we provide direct evidence that negative selection of maturing thymocytes is defective in CCR7-deficent mice. Impaired negative selection was observed after TCR/CD3 complex stimulation in vivo as well as in vitro and was prominent in both double-positive and semimature single positive cells (CD4+CD8−CD24high). It is noteworthy that thymocytes of CCR7−/− mice display defective negative selection in response to endogenous superantigens, demonstrating that the defect also occurs under physiological conditions. Disturbed negative selection was correlated with delayed activation kinetics and decreased calcium flux response of CCR7−/− thymocytes after in vitro TCR/CD3 stimulation, suggesting that an impaired response of CCR7−/− thymocytes via TCR-mediated signaling is responsible for defective negative selection in these mice.
Collapse
|
36
|
What do we know about the mechanisms of elimination of autoreactive T and B cells and what challenges remain. Immunol Cell Biol 2007; 86:57-66. [PMID: 18026176 DOI: 10.1038/sj.icb.7100141] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Tolerance to self-antigens within the adaptive immune system is safeguarded, at least in part, through deletion of autoreactive T and B lymphocytes. This deletion can occur during the development of these cells in primary lymphoid organs, the thymus or bone marrow, respectively, or at the mature stage in peripheral lymphoid tissues. Deletion of autoreactive lymphocytes is achieved to a large extent through apoptotic cell death. This review describes current understanding of the mechanisms that mediate apoptosis of autoreactive lymphocytes during their development in primary lymphoid organs and during their activation in the periphery. In particular, we discuss the roles of the proapoptotic Bcl-2 family member Bim and the small family of Nur77-related transcriptional regulators in lymphocyte negative selection. Finally, we speculate on the processes that may lead to the activation of Bim when antigen receptors are activated on autoreactive T or B cells.
Collapse
|
37
|
Jorgensen TN, McKee A, Wang M, Kushnir E, White J, Refaeli Y, Kappler JW, Marrack P. Bim and Bcl-2 mutually affect the expression of the other in T cells. THE JOURNAL OF IMMUNOLOGY 2007; 179:3417-24. [PMID: 17785775 DOI: 10.4049/jimmunol.179.6.3417] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The life and death of T cells is controlled to a large extent by the relative amounts of Bcl-2-related proteins they contain. The antiapoptotic protein Bcl-2 and the proapoptotic protein Bim are particularly important in this process with the amount of Bcl-2 per cell dropping by about one-half when T cells prepare to die. In this study we show that Bcl-2 and Bim each control the expression of the other. Absence of Bim leads to a drop in the amount of intracellular Bcl-2 protein, while having no effect on the amounts of mRNA for Bcl-2. Conversely, high amounts of Bcl-2 per cell allow high amounts of Bim, although in this case the effect involves increases in Bim mRNA. These mutual effects occur even if Bcl-2 is induced acutely. Thus these two proteins control the expression of the other, at either the protein or mRNA level.
Collapse
Affiliation(s)
- Trine N Jorgensen
- Integrated Department of Immunology, University of Colorado Health Sciences Center, Denver, CO 80262, USA
| | | | | | | | | | | | | | | |
Collapse
|
38
|
Abstract
Apoptosis is a conserved genetic program critical for the development and homeostasis of the immune system. During the early stages of lymphopoiesis, growth factor signaling is an essential regulator of homeostasis by regulating the survival of lymphocyte progenitors. During differentiation, apoptosis ensures that lymphocytes express functional antigen receptors and is essential for eliminating lymphocytes with dangerous self-reactive specificities. Many of these critical cell death checkpoints during immune development are regulated by the BCL-2 family of proteins, which is comprised of both pro- and antiapoptotic members, and members of the tumor necrosis factor death receptor family. Aberrations in the expression or function of these cell death modulators can result in pathological conditions including immune deficiency, autoimmunity, and cancer. This review will describe how apoptosis regulates these critical control points during immune development.
Collapse
Affiliation(s)
- J T Opferman
- Department of Biochemistry, St. Jude Children's Research Hospital, 332 N Lauderdale Street D-4063C, Memphis, TN 38105, USA.
| |
Collapse
|
39
|
Hamrouni A, Olsson A, Wiegers GJ, Villunger A. Impact of cellular lifespan on the T cell receptor repertoire. Eur J Immunol 2007; 37:1978-85. [PMID: 17559169 DOI: 10.1002/eji.200636632] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Pro-survival members of the Bcl-2 family are potent inhibitors of cell death and determine the lifespan of immature thymocytes by counteracting the intrinsically active apoptotic program in these cells. BH3-only proteins are potent antagonists of Bcl-2-like molecules and regulate death and survival of lymphocytes during their development and homeostasis. The intrinsic lifespan of CD4(+)8(+) double-positive thymocytes was reported to actively shape the diversity of the immune repertoire, since mice overexpressing Bcl-x(L) were reported to show a bias towards the usage of distal 3' Jalpha elements 1. To gain support for this concept, we analyzed TCRalpha rearrangements in T lymphocytes that show an extended lifespan due to either loss of the BH3-only protein Bim or overexpression of Bcl-2. A minor but reproducible skewing towards the usage of the more distal 3' Jalpha elements was observed in developing thymocytes and mature T cells from bim(-/-) and vav-bcl-2 transgenic mice, indicating that prolonged survival of double-positive thymocytes does have a significant impact on the selected TCRalpha repertoire. However, the changes that we observed were less pronounced than those found in lck-bcl-x(L) transgenic mice, pointing towards qualitative differences between Bcl-2- and Bcl-x(L)-mediated cell death inhibition during T cell development.
Collapse
MESH Headings
- Animals
- Apoptosis Regulatory Proteins/biosynthesis
- Bcl-2-Like Protein 11
- Blotting, Southern
- Cell Differentiation/immunology
- Cell Survival/immunology
- Flow Cytometry
- Gene Expression Regulation/immunology
- Gene Rearrangement, alpha-Chain T-Cell Antigen Receptor/genetics
- Gene Rearrangement, alpha-Chain T-Cell Antigen Receptor/immunology
- Membrane Proteins/biosynthesis
- Mice
- Mice, Transgenic
- Proto-Oncogene Proteins/biosynthesis
- Proto-Oncogene Proteins c-bcl-2/biosynthesis
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Reverse Transcriptase Polymerase Chain Reaction
- T-Lymphocytes/cytology
Collapse
Affiliation(s)
- Abdelbasset Hamrouni
- Division of Developmental Immunology, Biocenter, Innsbruck Medical University, Innsbruck, Austria
| | | | | | | |
Collapse
|
40
|
Erlacher M, Labi V, Manzl C, Böck G, Tzankov A, Häcker G, Michalak E, Strasser A, Villunger A. Puma cooperates with Bim, the rate-limiting BH3-only protein in cell death during lymphocyte development, in apoptosis induction. J Exp Med 2006; 203:2939-51. [PMID: 17178918 PMCID: PMC2118188 DOI: 10.1084/jem.20061552] [Citation(s) in RCA: 183] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The physiological role of B cell lymphoma 2 (Bcl-2) homology 3-only proteins has been investigated in mice lacking the individual genes identifying rate-limiting roles for Bim (Bcl-2-interacting mediator of cell death) and Puma (p53-up-regulated modulator of apoptosis) in apoptosis induction. The loss of Bim protects lymphocytes from apoptosis induced by cytokine deprivation and deregulated Ca++ flux and interferes with the deletion of autoreactive lymphocytes and the shutdown of immune responses. In contrast, Puma is considered the key mediator of p53-induced apoptosis. To investigate the hypothesis that Bim and Puma have overlapping functions, we generated mice lacking both genes and found that bim-/-/puma-/- animals develop multiple postnatal defects that are not observed in the single knockout mice. Most strikingly, hyperplasia of lymphatic organs is comparable with that observed in mice overexpressing Bcl-2 in all hemopoietic cells exceeding the hyperplasia observed in bim-/- mice. Bim and Puma also have clearly overlapping functions in p53-dependent and -independent apoptosis. Their combined loss promotes spontaneous tumorigenesis, causing the malignancies observed in Bcl-2 transgenic mice, but does not exacerbate the autoimmunity observed in the absence of Bim.
Collapse
Affiliation(s)
- Miriam Erlacher
- Division of Developmental Immunology, Biocenter, Innsbruck Medical University, A-6020 Innsbruck, Austria
| | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Iglesias-Serret D, de Frias M, Santidrián AF, Coll-Mulet L, Cosialls AM, Barragán M, Domingo A, Gil J, Pons G. Regulation of the proapoptotic BH3-only protein BIM by glucocorticoids, survival signals and proteasome in chronic lymphocytic leukemia cells. Leukemia 2006; 21:281-7. [PMID: 17151701 DOI: 10.1038/sj.leu.2404483] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Glucocorticoids induce apoptosis in chronic lymphocytic leukemia (CLL) cells through a caspase-dependent mechanism. However, their mechanism of action remains unknown. We have studied the regulation of the proapoptotic BH3-only Bcl-2 interacting mediator of cell death (BIM) in CLL cells. We demonstrate that glucocorticoids upregulate BIM at protein and mRNA levels. We have investigated the ability of different survival signals, such as 12-O-tetradecanoylphorbol 13-acetate (TPA), stromal cell-derived factor-1alpha (SDF-1alpha), interleukin 4 (IL-4) and B-cell receptor (BCR) activation, to influence the levels of BIM and its induction by glucocorticoids. TPA downregulates BIM(EL) by extracellular signal-regulated kinase (ERK)-mediated BIM phosphorylation and further proteasome-mediated degradation. However, SDF-1alpha and BCR activation induce transient BIM phosphorylation, without protein degradation. Proteasome inhibitors do not modify the levels of BIM with respect to untreated cells. However, they induce apoptosis and inhibit TPA-induced BIM(EL) degradation, leading to its accumulation. In conclusion, the results implicate BIM in glucocorticoid-induced apoptosis in CLL cells. BIM(EL) phosphorylation through the ERK pathway targets the protein for proteasomal degradation.
Collapse
Affiliation(s)
- D Iglesias-Serret
- Departament de Ciències Fisiològiques II, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain
| | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Adams JM, Huang DCS, Strasser A, Willis S, Chen L, Wei A, van Delft M, Fletcher JI, Puthalakath H, Kuroda J, Michalak EM, Kelly PN, Bouillet P, Villunger A, O'Reilly L, Bath ML, Smith DP, Egle A, Harris AW, Hinds M, Colman P, Cory S. Subversion of the Bcl-2 life/death switch in cancer development and therapy. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2006; 70:469-77. [PMID: 16869785 DOI: 10.1101/sqb.2005.70.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The Bcl-2 protein family, which largely determines commitment to apoptosis, has central roles in tumorigenesis and chemoresistance. Its three factions of interacting proteins include the BH3-only proteins (e.g., Bim, Puma, Bad, Noxa), which transduce diverse cytotoxic signals to the mammalian pro-survival proteins (Bcl-2, Bcl-x(L), Bcl-w, Mcl-1, A-1), whereas Bax and Bak, when freed from pro-survival constraint, provoke the mitochondrial permeabilization that triggers apoptosis. We have discovered unexpected specificity in their interactions. Only Bim and Puma, which mediate multiple cytotoxic signals, engage all the pro-survival proteins. Noxa and Bad instead bind subsets and cooperate in killing, indicating that apoptosis requires neutralization of different pro-survival subsets. Furthermore, Mcl-1 and Bcl-x(L), but not Bcl-2, directly sequester Bak in healthy cells, and Bak is freed only when BH3-only proteins neutralize both its guards. BH3-only proteins such as Bim are tumor suppressors and mediate many of the cytotoxic signals from anticancer agents. Hence, compounds mimicking them may prove valuable for therapy. Indeed, the recently described ABT-737 is a promising "BH3 mimetic" of Bad. We find that, like Bad, ABT-737 kills cells efficiently only if Mcl-1 is absent or down-regulated. Thus, manipulation of apoptosis by targeting the Bcl-2 family has exciting potential for cancer treatment.
Collapse
Affiliation(s)
- J M Adams
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Kiss I, Oskolás H, Tóth R, Bouillet P, Tóth K, Fülöp A, Scholtz B, Ledent C, Fésüs L, Szondy Z. Adenosine A2A receptor-mediated cell death of mouse thymocytes involves adenylate cyclase and Bim and is negatively regulated by Nur77. Eur J Immunol 2006; 36:1559-71. [PMID: 16673448 DOI: 10.1002/eji.200535334] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Adenosine is generated in the microenvironment of emerging thymocytes through normal mechanisms of lymphocyte selection. In a normal thymus, most of the adenosine is catabolized by adenosine deaminase; however, in an environment where up to 95% of the cells undergo programmed cell death, a sufficient amount of adenosine is accumulated to trigger cell surface adenosine receptors. Here we show that accumulated adenosine can induce apoptosis in immature mouse thymocytes, mostly via adenosine A(2A) receptors. The signaling pathway is coupled to adenylate cyclase activation, induction of the Nur77 transcription factor, Nur77-dependent genes, such as Fas ligand and TRAIL, and the pro-apoptotic BH3-only protein Bim. We analyzed several knockout and transgenic mouse lines and found that adenosine-induced killing of mouse thymocytes requires Bim, occurs independently of "death receptor" signaling and is inhibited by Bcl-2 and Nur77. Collectively our data demonstrate that adenosine-induced cell death involves signaling pathways originally found in negative selection of thymocytes and suggest a determining role of Bim and a regulatory role for Nur77.
Collapse
MESH Headings
- Adenosine/immunology
- Adenylyl Cyclases/immunology
- Animals
- Apoptosis/drug effects
- Apoptosis/immunology
- BH3 Interacting Domain Death Agonist Protein/genetics
- BH3 Interacting Domain Death Agonist Protein/immunology
- Blotting, Western
- Cyclic AMP/immunology
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/immunology
- Fas Ligand Protein
- Male
- Membrane Glycoproteins/immunology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Nuclear Receptor Subfamily 4, Group A, Member 1
- Proto-Oncogene Proteins c-bcl-2/immunology
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- Receptor, Adenosine A2A/immunology
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/immunology
- Receptors, Steroid/genetics
- Receptors, Steroid/immunology
- Reverse Transcriptase Polymerase Chain Reaction
- T-Lymphocytes/cytology
- T-Lymphocytes/enzymology
- T-Lymphocytes/immunology
- Transcription Factors/genetics
- Transcription Factors/immunology
- Tumor Necrosis Factors/immunology
Collapse
Affiliation(s)
- Ildikó Kiss
- Department of Biochemistry and Molecular Biology, Signaling and Apoptosis Research Group, Hungarian Academy of Sciences, Research Center of Molecular Medicine, University of Debrecen
| | | | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Alves NL, Derks IAM, Berk E, Spijker R, van Lier RAW, Eldering E. The Noxa/Mcl-1 Axis Regulates Susceptibility to Apoptosis under Glucose Limitation in Dividing T Cells. Immunity 2006; 24:703-716. [PMID: 16782027 DOI: 10.1016/j.immuni.2006.03.018] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Revised: 02/22/2006] [Accepted: 03/14/2006] [Indexed: 01/13/2023]
Abstract
Throughout lymphocyte development, cellular persistence and expansion are tightly regulated by survival and apoptosis. Within the Bcl-2 family, distinct apoptogenic BH3-only members like Bid, Bim, and Puma appear to function in specific cell death pathways. We found that naive human T cells after mitogenic activation, apart from expected protective Bcl-2 members, also rapidly upregulate the BH3-only protein Noxa in a p53-independent fashion. The specific role of Noxa became apparent during glucose limitation and involves interaction with the labile Bcl-2 homolog Mcl-1. Knockdown of Noxa or Mcl-1 results in protection or susceptibility, respectively, to apoptosis induced by glucose deprivation. Declining Mcl-1 levels and apoptosis induction are inversely correlated to Noxa levels and prevented by readdition of glucose. We propose that the Noxa/Mcl-1 axis is an apoptosis rheostat in dividing cells, in a selective pathway that functions to restrain lymphocyte expansion and can be triggered by glucose deprivation.
Collapse
Affiliation(s)
- Nuno L Alves
- Department of Experimental Immunology, Academic Medical Center, 1005 AZ Amsterdam, The Netherlands
| | - Ingrid A M Derks
- Department of Experimental Immunology, Academic Medical Center, 1005 AZ Amsterdam, The Netherlands
| | - Erik Berk
- Department of Experimental Immunology, Academic Medical Center, 1005 AZ Amsterdam, The Netherlands
| | - René Spijker
- Department of Experimental Immunology, Academic Medical Center, 1005 AZ Amsterdam, The Netherlands; Department of Hematology, Academic Medical Center, 1005 AZ Amsterdam, The Netherlands
| | - René A W van Lier
- Department of Experimental Immunology, Academic Medical Center, 1005 AZ Amsterdam, The Netherlands
| | - Eric Eldering
- Department of Experimental Immunology, Academic Medical Center, 1005 AZ Amsterdam, The Netherlands.
| |
Collapse
|
45
|
Abstract
Caspases are responsible for crucial aspects of inflammation and immune-cell death that are disrupted in a number of genetic autoimmune and autoinflammatory diseases. The caspase family of proteases can be divided into pro-apoptotic and pro-inflammatory members based on their substrate specificity and participation in separate signalling cascades. However, as discussed here, evidence has emerged over the past few years that a number of the caspases thought to be involved solely in apoptosis also contribute to specific aspects of immune-cell development, activation and differentiation, and can even protect cells from some forms of cell death.
Collapse
Affiliation(s)
- Richard M Siegel
- Immunoregulation Unit, Autoimmunity Branch, NIAMS, National Institutes of Health, Building 10 Room 9N238, Bethesda, Maryland 20892, USA.
| |
Collapse
|
46
|
Uldrich AP, Berzins SP, Malin MA, Bouillet P, Strasser A, Smyth MJ, Boyd RL, Godfrey DI. Antigen challenge inhibits thymic emigration. THE JOURNAL OF IMMUNOLOGY 2006; 176:4553-61. [PMID: 16585545 DOI: 10.4049/jimmunol.176.8.4553] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
T cell development in the thymus involves a series of TCR-mediated control points including TCR-beta selection and positive and negative selection. Approximately half of the thymic sojourn is spent in the medulla, where thymocytes undergo final maturation before emigrating to the periphery. Although it is acknowledged that thymic emigration is an active process, relatively little is known about how this is regulated, why it takes so long, and whether TCR-mediated signaling can influence this step. Using wild-type and TCR transgenic mice, we found that Ag injected i.v. or intrathymically led to a striking reduction in the number of recent thymic emigrants (RTE) in the periphery. This was caused by inhibition of T cell export rather than peripheral deletion, because a cohort of RTE that was already released before in vivo Ag challenge was not depleted, and similar results were observed in Bim-deficient mice, which have impaired T cell deletion. Within the thymus, the loss of RTE was associated with retention of medullary thymocytes rather than increased negative selection. In addition to Ag-specific inhibition of export, some TCR-independent suppression of emigration was also observed that appeared to be partly the result of the inflammatory cytokine TNF. Thus, in addition to its accepted role in intrathymic selection events, TCR signaling can also play an important role in the regulation of thymic emigration.
Collapse
MESH Headings
- Animals
- Antigens/administration & dosage
- Cell Movement/immunology
- Enterotoxins/administration & dosage
- Enterotoxins/immunology
- Injections, Intralymphatic
- Injections, Intravenous
- Mice
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/metabolism
- Signal Transduction
- Superantigens/administration & dosage
- T-Lymphocytes/cytology
- T-Lymphocytes/immunology
- T-Lymphocytes/physiology
- Thymus Gland/cytology
- Thymus Gland/immunology
Collapse
Affiliation(s)
- Adam P Uldrich
- Department of Microbiology and Immunology, University of Melbourne, Parkville, Victoria, Australia.
| | | | | | | | | | | | | | | |
Collapse
|
47
|
El Chami N, Ikhlef F, Kaszas K, Yakoub S, Tabone E, Siddeek B, Cunha S, Beaudoin C, Morel L, Benahmed M, Régnier DC. Androgen-dependent apoptosis in male germ cells is regulated through the proto-oncoprotein Cbl. ACTA ACUST UNITED AC 2006; 171:651-61. [PMID: 16301331 PMCID: PMC2171555 DOI: 10.1083/jcb.200507076] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The proto-oncoprotein Cbl is known to control several signaling processes. It is highly expressed in the testis, and because spermatogenesis is androgen dependent, we investigated the androgen dependency expression of Cbl through its testicular sublocalization and its expression levels in rats that were exposed to the antiandrogen flutamide or were hypophysectomized. We report the androgen dependency of Cbl as it localizes in pachytene spermatocytes during androgen-dependent stages, is down-regulated upon flutamide exposure, and is up-regulated with testosterone in hypophysectomized rats. Coculture experiments showed the key control exerted by the Sertoli cell on Cbl activity. As flutamide induces germ cell apoptosis, we investigate members of the Bcl-2 family upon flutamide exposure. We show that the proapoptotic Bcl-2 family member Bim mirrored Cbl expression through a posttranscriptional process. We also show that in Cbl knockout mouse testes, the imbalance between the high expression of Bim and Smac/Diablo and antiapoptotic factors such as cellular inhibitor of apoptosis 2 favors a survival process, which makes these mice unresponsive to androgen withdrawal and could explain their hypofertility.
Collapse
Affiliation(s)
- Nisrine El Chami
- Faculté de Médecine Lyon-Sud, Institut National de la Santé et la Recherche Médicale, F-69921 Oullins Cedex, France
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Fischer AM, Katayama CD, Pagès G, Pouysségur J, Hedrick SM. The role of erk1 and erk2 in multiple stages of T cell development. Immunity 2005; 23:431-43. [PMID: 16226508 DOI: 10.1016/j.immuni.2005.08.013] [Citation(s) in RCA: 266] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2005] [Revised: 08/04/2005] [Accepted: 08/31/2005] [Indexed: 11/20/2022]
Abstract
Activation of extracellular-signal-regulated protein kinase (Erk) is central to growth-factor-receptor-mediated signaling including that originating from the T cell antigen receptor. It integrates cytoplasmic signals to effect changes in transcription associated with differentiation, proliferation, and survival. In this report, we present an analysis of mice with targeted deletions in Erk1 and Erk2 to assess the relationship between Erk activity and cell-cycle progression, thymocyte development, and lineage commitment. These studies show that Erk is selectively retained during beta selection-driven proliferation, and yet Erk1/2 are not required to complete differentiation to CD4+CD8+ preselection stage of development. Erk activity is essential for the process of positive selection, and it differentially affects CD4 and CD8 T cell maturation; yet, diminished expression itself is not sufficient to alter lineage commitment.
Collapse
Affiliation(s)
- April M Fischer
- Division of Biological Sciences, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093-0377, USA
| | | | | | | | | |
Collapse
|
49
|
Bunin A, Khwaja FW, Kersh GJ. Regulation of Bim by TCR signals in CD4/CD8 double-positive thymocytes. THE JOURNAL OF IMMUNOLOGY 2005; 175:1532-9. [PMID: 16034091 DOI: 10.4049/jimmunol.175.3.1532] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Bim, a BH3-only Bcl-2 family member, is required for apoptosis of thymocytes in response to negative selection signals. Regulation of the apoptotic activity of Bim during negative selection is not understood. In this study we demonstrate that in murine thymocytes undergoing apoptosis in response to anti-CD3epsilon injection, levels of Bim protein expression do not change. In immature thymocytes, Bim is associated with mitochondria before stimulation and is not regulated by a change in subcellular localization during apoptosis. We also show that Bim(EL) is rapidly phosphorylated in thymocytes in response to CD3epsilon cross-linking both in vivo and in vitro, and that phosphorylation is sustained for at least 24 h. Analysis of MHC-deficient mice shows that phosphorylation of Bim occurs in CD4/CD8 double-positive thymocytes and does not depend on activation of mature T cells. We also find that TCR cross-linking on thymocytes induces an increase in the proportion of Bcl-x(L) bound to Bim at late time points. Our results favor a model in which strong TCR signals regulate the apoptotic activity of Bim by phosphorylation and subsequent changes in binding to Bcl-x(L) in immature thymocytes.
Collapse
MESH Headings
- Animals
- Antibodies, Monoclonal/administration & dosage
- Apoptosis/immunology
- Apoptosis Regulatory Proteins
- Bcl-2-Like Protein 11
- CD3 Complex/immunology
- CD4 Antigens/biosynthesis
- CD8 Antigens/biosynthesis
- Carrier Proteins/biosynthesis
- Carrier Proteins/metabolism
- Cross-Linking Reagents/metabolism
- Dexamethasone/administration & dosage
- Dose-Response Relationship, Immunologic
- Injections, Intravenous
- Membrane Proteins/biosynthesis
- Membrane Proteins/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microtubules/metabolism
- Models, Immunological
- Phosphorylation
- Protein Binding/drug effects
- Protein Binding/immunology
- Proto-Oncogene Proteins/biosynthesis
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-bcl-2/metabolism
- Receptors, Antigen, T-Cell/immunology
- Receptors, Antigen, T-Cell/metabolism
- Receptors, Antigen, T-Cell/physiology
- Signal Transduction/immunology
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- Thymus Gland/cytology
- Thymus Gland/immunology
- Thymus Gland/metabolism
- bcl-X Protein
Collapse
Affiliation(s)
- Anna Bunin
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | | | | |
Collapse
|
50
|
Webb LMC, Vigorito E, Wymann MP, Hirsch E, Turner M. Cutting edge: T cell development requires the combined activities of the p110gamma and p110delta catalytic isoforms of phosphatidylinositol 3-kinase. THE JOURNAL OF IMMUNOLOGY 2005; 175:2783-7. [PMID: 16116162 DOI: 10.4049/jimmunol.175.5.2783] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The role of PI3K activity in T lymphocyte development is obscure because mice deficient in single PI3K catalytic subunits either die before birth (p110alpha-/- and p110beta-/-) or lack a significant T cell developmental phenotype (p110gamma-/- and p110delta-/-). We have generated mice deficient in both p110gamma and p110delta and show that p110gamma/delta-/- mice have a profound block in T cell development that occurs at the beta-selection checkpoint. We show that pre-TCR-induced signaling is significantly reduced in p110gamma/delta-/- thymocytes and that this results in a concomitant lack of proliferative expansion and increased apoptosis. The survival defect in p110gamma/delta-/- thymocytes is associated with increased levels of the pro-apoptotic molecule Bcl2 interacting mediator of cell death. This work demonstrates that PI3K activity is critical for T cell development and depends on the combined function of p110gamma and p110delta.
Collapse
Affiliation(s)
- Louise M C Webb
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Babraham, Cambridge, United Kingdom.
| | | | | | | | | |
Collapse
|