1
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Sevilla-Movilla S, Fuentes P, Rodríguez-García Y, Arellano-Sánchez N, Krenn PW, de Val SI, Montero-Herradón S, García-Ceca J, Burdiel-Herencia V, Gardeta SR, Aguilera-Montilla N, Barrio-Alonso C, Crainiciuc G, Bouvard D, García-Pardo A, Zapata AG, Hidalgo A, Fässler R, Carrasco YR, Toribio ML, Teixidó J. ICAP-1 loss impairs CD8 + thymocyte development and leads to reduced marginal zone B cells in mice. Eur J Immunol 2022; 52:1228-1242. [PMID: 35491946 PMCID: PMC9543158 DOI: 10.1002/eji.202149560] [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: 08/02/2021] [Revised: 03/15/2022] [Accepted: 04/29/2022] [Indexed: 11/12/2022]
Abstract
ICAP‐1 regulates β1‐integrin activation and cell adhesion. Here, we used ICAP‐1‐null mice to study ICAP‐1 potential involvement during immune cell development and function. Integrin α4β1‐dependent adhesion was comparable between ICAP‐1‐null and control thymocytes, but lack of ICAP‐1 caused a defective single‐positive (SP) CD8+ cell generation, thus, unveiling an ICAP‐1 involvement in SP thymocyte development. ICAP‐1 bears a nuclear localization signal and we found it displayed a strong nuclear distribution in thymocytes. Interestingly, there was a direct correlation between the lack of ICAP‐1 and reduced levels in SP CD8+ thymocytes of Runx3, a transcription factor required for CD8+ thymocyte generation. In the spleen, ICAP‐1 was found evenly distributed between cytoplasm and nuclear fractions, and ICAP‐1–/– spleen T and B cells displayed upregulation of α4β1‐mediated adhesion, indicating that ICAP‐1 negatively controls their attachment. Furthermore, CD3+‐ and CD19+‐selected spleen cells from ICAP‐1‐null mice showed reduced proliferation in response to T‐ and B‐cell stimuli, respectively. Finally, loss of ICAP‐1 caused a remarkable decrease in marginal zone B‐ cell frequencies and a moderate increase in follicular B cells. Together, these data unravel an ICAP‐1 involvement in the generation of SP CD8+ thymocytes and in the control of marginal zone B‐cell numbers.
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Affiliation(s)
- Silvia Sevilla-Movilla
- Department of Molecular Biomedicine, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Madrid, Spain
| | - Patricia Fuentes
- Development and Function of the Immune System Unit, Centro de Biología Molecular Severo Ochoa, CSIC, Universidad Autónoma de Madrid, Madrid, Spain
| | - Yaiza Rodríguez-García
- Department of Molecular Biomedicine, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Madrid, Spain
| | - Nohemi Arellano-Sánchez
- Department of Molecular Biomedicine, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Madrid, Spain
| | - Peter W Krenn
- Department of Molecular Medicine, Max Planck Institute of Biochemistry, Martinsried, Germany.,Present address: Paris-Lodron Universität Salzburg, Austria
| | - Soledad Isern de Val
- Department of Molecular Biomedicine, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Madrid, Spain
| | - Sara Montero-Herradón
- Department of Cell Biology; Faculty of Biology, Complutense University of Madrid, Madrid, 28040.,Spain and Health Research Institute, Hospital 12 de Octubre (imas12), Madrid, 28041, Spain
| | - Javier García-Ceca
- Department of Cell Biology; Faculty of Biology, Complutense University of Madrid, Madrid, 28040.,Spain and Health Research Institute, Hospital 12 de Octubre (imas12), Madrid, 28041, Spain
| | - Valeria Burdiel-Herencia
- Department of Molecular Biomedicine, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Madrid, Spain
| | - Sofía R Gardeta
- Department on Immunology and Oncology, Centro Nacional de Biotecnología (CNB)-CSIC, Madrid, 28049, Spain
| | - Noemí Aguilera-Montilla
- Department of Molecular Biomedicine, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Madrid, Spain
| | - Celia Barrio-Alonso
- Department of Molecular Biomedicine, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Madrid, Spain.,Present address: Hospital General Universitario Gregorio Marañón, Madrid, Spain
| | - Georgiana Crainiciuc
- Area of Developmental and Cell Biology, Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, 28029, Spain.,Institute for Cardiovascular Prevention, Ludwig-Maximilians University, Munich, 80336, Germany
| | - Daniel Bouvard
- Centre de Recherche en Biologie Cellulaire de Montpellier, Montpellier, France
| | - Angeles García-Pardo
- Department of Molecular Biomedicine, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Madrid, Spain
| | - Agustin G Zapata
- Department of Cell Biology; Faculty of Biology, Complutense University of Madrid, Madrid, 28040.,Spain and Health Research Institute, Hospital 12 de Octubre (imas12), Madrid, 28041, Spain
| | - Andrés Hidalgo
- Area of Developmental and Cell Biology, Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, 28029, Spain.,Institute for Cardiovascular Prevention, Ludwig-Maximilians University, Munich, 80336, Germany
| | - Reinhard Fässler
- Department of Molecular Medicine, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Yolanda R Carrasco
- Department on Immunology and Oncology, Centro Nacional de Biotecnología (CNB)-CSIC, Madrid, 28049, Spain
| | - Maria L Toribio
- Development and Function of the Immune System Unit, Centro de Biología Molecular Severo Ochoa, CSIC, Universidad Autónoma de Madrid, Madrid, Spain
| | - Joaquin Teixidó
- Department of Molecular Biomedicine, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Madrid, Spain
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2
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Balcells F, Martínez Monteros MJ, Gómez AL, Cazorla SI, Perdigón G, Maldonado-Galdeano C. Probiotic Consumption Boosts Thymus in Obesity and Senescence Mouse Models. Nutrients 2022; 14:nu14030616. [PMID: 35276973 PMCID: PMC8838891 DOI: 10.3390/nu14030616] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 01/21/2022] [Accepted: 01/23/2022] [Indexed: 02/01/2023] Open
Abstract
The ability of the immune system to respond to different pathogens throughout life requires the constant production and selection of T cells in the thymus. This immune organ is very sensitive to age, infectious processes and nutrition disorders (obesity and malnutrition). Several studies have shown that the incorporation of some probiotic bacteria or probiotic fermented milk in the diet has beneficial effects, not only at the intestinal level but also on distant mucosal tissues, improving the architecture of the thymus in a malnutrition model. The aim of the present study was to determine whether supplementation with the probiotic strain Lactobacillus casei CRL 431 and/or its cell wall could improve body weight, intestinal microbiota and thymus structure and function in both obese and aging mice. We evaluated probiotic administration to BALB/c mice in 2 experimental mouse models: obesity and senescence, including mice of different ages (21, 28, 45, 90 and 180 days). Changes in thymus size and histology were recorded. T-lymphocyte population and cytokine production were also determined. The consumption of probiotics improved the cortical/medullary ratio, the production and regulation of cytokines and the recovery of mature T-lymphocyte populations of the thymus in obese and old mice. Probiotic incorporation into the diet could not only modulate the immune system but also lead to thymus function recovery, thus improving quality of life.
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Affiliation(s)
- Florencia Balcells
- Laboratorio de Inmunología, Centro de Referencia para Lactobacilos (CERELA-CONICET), San Miguel de Tucumán 4000, Argentina; (F.B.); (M.J.M.M.); (S.I.C.); (G.P.)
| | - María José Martínez Monteros
- Laboratorio de Inmunología, Centro de Referencia para Lactobacilos (CERELA-CONICET), San Miguel de Tucumán 4000, Argentina; (F.B.); (M.J.M.M.); (S.I.C.); (G.P.)
| | - Alba Lorena Gómez
- PatLab Laboratorio de Anatomía Patológica Citopatología e Inmunohistoquímica, San Miguel de Tucumán 4000, Argentina;
| | - Silvia Inés Cazorla
- Laboratorio de Inmunología, Centro de Referencia para Lactobacilos (CERELA-CONICET), San Miguel de Tucumán 4000, Argentina; (F.B.); (M.J.M.M.); (S.I.C.); (G.P.)
- Cátedra de Inmunología, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Miguel de Tucumán 4000, Argentina
| | - Gabriela Perdigón
- Laboratorio de Inmunología, Centro de Referencia para Lactobacilos (CERELA-CONICET), San Miguel de Tucumán 4000, Argentina; (F.B.); (M.J.M.M.); (S.I.C.); (G.P.)
| | - Carolina Maldonado-Galdeano
- Laboratorio de Inmunología, Centro de Referencia para Lactobacilos (CERELA-CONICET), San Miguel de Tucumán 4000, Argentina; (F.B.); (M.J.M.M.); (S.I.C.); (G.P.)
- Cátedra de Inmunología, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Miguel de Tucumán 4000, Argentina
- Correspondence:
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3
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Chopp LB, Gopalan V, Ciucci T, Ruchinskas A, Rae Z, Lagarde M, Gao Y, Li C, Bosticardo M, Pala F, Livak F, Kelly MC, Hannenhalli S, Bosselut R. An Integrated Epigenomic and Transcriptomic Map of Mouse and Human αβ T Cell Development. Immunity 2020; 53:1182-1201.e8. [PMID: 33242395 PMCID: PMC8641659 DOI: 10.1016/j.immuni.2020.10.024] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 08/25/2020] [Accepted: 10/29/2020] [Indexed: 12/13/2022]
Abstract
αβ lineage T cells, most of which are CD4+ or CD8+ and recognize MHC I- or MHC II-presented antigens, are essential for immune responses and develop from CD4+CD8+ thymocytes. The absence of in vitro models and the heterogeneity of αβ thymocytes have hampered analyses of their intrathymic differentiation. Here, combining single-cell RNA and ATAC (chromatin accessibility) sequencing, we identified mouse and human αβ thymocyte developmental trajectories. We demonstrated asymmetric emergence of CD4+ and CD8+ lineages, matched differentiation programs of agonist-signaled cells to their MHC specificity, and identified correspondences between mouse and human transcriptomic and epigenomic patterns. Through computational analysis of single-cell data and binding sites for the CD4+-lineage transcription factor Thpok, we inferred transcriptional networks associated with CD4+- or CD8+-lineage differentiation, and with expression of Thpok or of the CD8+-lineage factor Runx3. Our findings provide insight into the mechanisms of CD4+ and CD8+ T cell differentiation and a foundation for mechanistic investigations of αβ T cell development.
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Affiliation(s)
- Laura B Chopp
- Laboratory of Immune Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA; Immunology Graduate Group, University of Pennsylvania Medical School, Philadelphia, PA, USA
| | - Vishaka Gopalan
- Cancer Data Science Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Thomas Ciucci
- Laboratory of Immune Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Allison Ruchinskas
- Cancer Research Technology Program, Single Cell Analysis Facility, Frederick National Laboratory for Cancer Research, Bethesda, MD, USA
| | - Zachary Rae
- Cancer Research Technology Program, Single Cell Analysis Facility, Frederick National Laboratory for Cancer Research, Bethesda, MD, USA
| | - Manon Lagarde
- Laboratory of Immune Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Yayi Gao
- Laboratory of Immune Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Caiyi Li
- Laboratory of Genomic Integrity, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Marita Bosticardo
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Francesca Pala
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Ferenc Livak
- Laboratory of Genomic Integrity, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Michael C Kelly
- Cancer Research Technology Program, Single Cell Analysis Facility, Frederick National Laboratory for Cancer Research, Bethesda, MD, USA
| | - Sridhar Hannenhalli
- Cancer Data Science Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Rémy Bosselut
- Laboratory of Immune Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
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4
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Rushdi M, Li K, Yuan Z, Travaglino S, Grakoui A, Zhu C. Mechanotransduction in T Cell Development, Differentiation and Function. Cells 2020; 9:E364. [PMID: 32033255 PMCID: PMC7072571 DOI: 10.3390/cells9020364] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 01/16/2020] [Accepted: 01/17/2020] [Indexed: 02/07/2023] Open
Abstract
Cells in the body are actively engaging with their environments that include both biochemical and biophysical aspects. The process by which cells convert mechanical stimuli from their environment to intracellular biochemical signals is known as mechanotransduction. Exemplifying the reliance on mechanotransduction for their development, differentiation and function are T cells, which are central to adaptive immune responses. T cell mechanoimmunology is an emerging field that studies how T cells sense, respond and adapt to the mechanical cues that they encounter throughout their life cycle. Here we review different stages of the T cell's life cycle where existing studies have shown important effects of mechanical force or matrix stiffness on a T cell as sensed through its surface molecules, including modulating receptor-ligand interactions, inducing protein conformational changes, triggering signal transduction, amplifying antigen discrimination and ensuring directed targeted cell killing. We suggest that including mechanical considerations in the immunological studies of T cells would inform a more holistic understanding of their development, differentiation and function.
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Affiliation(s)
- Muaz Rushdi
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; (M.R.); (K.L.); (S.T.)
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA;
| | - Kaitao Li
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; (M.R.); (K.L.); (S.T.)
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA;
| | - Zhou Yuan
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA;
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30313, USA
| | - Stefano Travaglino
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; (M.R.); (K.L.); (S.T.)
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA;
| | - Arash Grakoui
- Emory Vaccine Center, Division of Microbiology and Immunology, Yerkes Research Primate Center, Emory University School of Medicine, Atlanta, GA 30329, USA;
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Cheng Zhu
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; (M.R.); (K.L.); (S.T.)
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA;
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30313, USA
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5
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Kurd NS, Lutes LK, Yoon J, Chan SW, Dzhagalov IL, Hoover AR, Robey EA. A role for phagocytosis in inducing cell death during thymocyte negative selection. eLife 2019; 8:48097. [PMID: 31868579 PMCID: PMC6957271 DOI: 10.7554/elife.48097] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 12/21/2019] [Indexed: 12/11/2022] Open
Abstract
Autoreactive thymocytes are eliminated during negative selection in the thymus, a process important for establishing self-tolerance. Thymic phagocytes serve to remove dead thymocytes, but whether they play additional roles during negative selection remains unclear. Here, using a murine thymic slice model in which thymocytes undergo negative selection in situ, we demonstrate that phagocytosis promotes negative selection, and provide evidence for the escape of autoreactive CD8 T cells to the periphery when phagocytosis in the thymus is impaired. We also show that negative selection is more efficient when the phagocyte also presents the negative selecting peptide. Our findings support a model for negative selection in which the death process initiated following strong TCR signaling is facilitated by phagocytosis. Thus, the phagocytic capability of cells that present self-peptides is a key determinant of thymocyte fate.
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Affiliation(s)
- Nadia S Kurd
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Lydia K Lutes
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Jaewon Yoon
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Shiao Wei Chan
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Ivan L Dzhagalov
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Ashley R Hoover
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Ellen A Robey
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
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6
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Abstract
The ability of T cells to respond to a wide array of foreign antigens while avoiding reactivity to self is largely determined by cellular selection of developing T cells in the thymus. While a great deal is known about the cell types and molecules involved in T-cell selection in the thymus, our understanding of the spatial and temporal aspects of this process remain relatively poorly understood. Thymocytes are highly motile within the thymus and travel between specialized microenvironments at different phases of their development while interacting with distinct sets of self-peptides and peptide presenting cells. A knowledge of when, where, and how thymocytes encounter self-peptide MHC ligands at different stages of thymic development is key to understanding T-cell selection. In the past several years, our laboratory has investigated this topic using two-photon time-lapse microscopy to directly visualize thymocyte migration and signaling events, together with a living thymic slice preparation to provide a synchronized experimental model of T-cell selection in situ. Here, we discuss recent advances in our understanding of the temporal and spatial aspects of T-cell selection, highlighting our own work, and placing them in the context of work from other groups.
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Affiliation(s)
- Nadia Kurd
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Ellen A Robey
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, 94720, USA
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7
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Kimura MY, Thomas J, Tai X, Guinter TI, Shinzawa M, Etzensperger R, Li Z, Love P, Nakayama T, Singer A. Timing and duration of MHC I positive selection signals are adjusted in the thymus to prevent lineage errors. Nat Immunol 2016; 17:1415-1423. [PMID: 27668801 DOI: 10.1038/ni.3560] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Accepted: 08/17/2016] [Indexed: 12/12/2022]
Abstract
Major histocompatibility complex class I (MHC I) positive selection of CD8+ T cells in the thymus requires that T cell antigen receptor (TCR) signaling end in time for cytokines to induce Runx3d, the CD8-lineage transcription factor. We examined the time required for these events and found that the overall duration of positive selection was similar for all CD8+ thymocytes in mice, despite markedly different TCR signaling times. Notably, prolonged TCR signaling times were counter-balanced by accelerated Runx3d induction by cytokines and accelerated differentiation into CD8+ T cells. Consequently, lineage errors did not occur except when MHC I-TCR signaling was so prolonged that the CD4-lineage-specifying transcription factor ThPOK was expressed, preventing Runx3d induction. Thus, our results identify a compensatory signaling mechanism that prevents lineage-fate errors by dynamically modulating Runx3d induction rates during MHC I positive selection.
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Affiliation(s)
- Motoko Y Kimura
- Experimental Immunology Branch, National Cancer Institute, US National Institutes of Health, Bethesda, Maryland, USA
| | - Julien Thomas
- Experimental Immunology Branch, National Cancer Institute, US National Institutes of Health, Bethesda, Maryland, USA
| | - Xuguang Tai
- Experimental Immunology Branch, National Cancer Institute, US National Institutes of Health, Bethesda, Maryland, USA
| | - Terry I Guinter
- Experimental Immunology Branch, National Cancer Institute, US National Institutes of Health, Bethesda, Maryland, USA
| | - Miho Shinzawa
- Experimental Immunology Branch, National Cancer Institute, US National Institutes of Health, Bethesda, Maryland, USA
| | - Ruth Etzensperger
- Experimental Immunology Branch, National Cancer Institute, US National Institutes of Health, Bethesda, Maryland, USA
| | - Zhenhu Li
- Laboratory of Mammalian Genes and Development, Eunice Kennedy Schriver National Institute of Child Health and Human Development, US National Institutes of Health, Bethesda, Maryland, USA
| | - Paul Love
- Laboratory of Mammalian Genes and Development, Eunice Kennedy Schriver National Institute of Child Health and Human Development, US National Institutes of Health, Bethesda, Maryland, USA
| | | | - Alfred Singer
- Experimental Immunology Branch, National Cancer Institute, US National Institutes of Health, Bethesda, Maryland, USA
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8
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Wagner DH. Of the multiple mechanisms leading to type 1 diabetes, T cell receptor revision may play a prominent role (is type 1 diabetes more than a single disease?). Clin Exp Immunol 2016; 185:271-80. [PMID: 27271348 DOI: 10.1111/cei.12819] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 05/20/2016] [Accepted: 05/31/2016] [Indexed: 12/30/2022] Open
Abstract
A single determinant factor for autoimmunity does not exist; disease development probably involves contributions from genetics, the environment and immune dysfunction. Type 1 diabetes is no exception. Genomewide-associated studies (GWAS) analysis in T1D has proved disappointing in revealing contributors to disease prediction; the only reliable marker has been human leucocyte antigen (HLA). Specific HLAs include DR3/DR4/DQ2/DQ8, for example. Because HLA molecules present antigen to T cells, it is reasonable that certain HLA molecules have a higher affinity to present self-antigen. Recent studies have shown that additional polymorphisms in HLA that are restricted to autoimmune conditions are further contributory. A caveat is that not all individuals with the appropriate 'pro-autoimmune' HLA develop an autoimmune disease. Another crucial component is autoaggressive T cells. Finding a biomarker to discriminate autoaggressive T cells has been elusive. However, a subset of CD4 helper cells that express the CD40 receptor have been described as becoming pathogenic. An interesting function of CD40 on T cells is to induce the recombination-activating gene (RAG)1/RAG2 T cell receptor recombination machinery. This observation is contrary to immunology paradigms that changes in TCR molecules cannot take place outside the thymic microenvironment. Alteration in TCR, called TCR revision, not only occurs, but may help to account for the development of autoaggressive T cells. Another interesting facet is that type 1 diabetes (T1D) may be more than a single disease; that is, multiple cellular components contribute uniquely, but result ultimately in the same clinical outcome, T1D. This review considers the process of T cell maturation and how that could favor auto-aggressive T cell development in T1D. The potential contribution of TCR revision to autoimmunity is also considered.
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Affiliation(s)
- D H Wagner
- Department of Medicine, Department of Neurology, Webb-Waring Center, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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9
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Abstract
A critical function of the thymus is to help enforce tolerance to self. The importance of central tolerance in preventing autoimmunity has been enlightened by a deeper understanding of the interactions of developing T cells with a diverse population of thymic antigen presenting cell populations. Furthermore, there has been rapid progress in our understanding of how autoreactive T cell specificities are diverted into the T regulatory lineage. Here we review and highlight the recent progress in how tolerance is imposed on the developing thymocyte repertoire.
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Affiliation(s)
- Maria L Mouchess
- Diabetes Center, University of California-San Francisco, Box 0540, San Francisco, CA, 94143, USA
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10
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Distinct phases in the positive selection of CD8+ T cells distinguished by intrathymic migration and T-cell receptor signaling patterns. Proc Natl Acad Sci U S A 2014; 111:E2550-8. [PMID: 24927565 DOI: 10.1073/pnas.1408482111] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Positive selection of CD8 T cells in the thymus is thought to be a multistep process lasting 3-4 d; however, the discrete steps involved are poorly understood. Here, we examine phenotypic changes, calcium signaling, and intrathymic migration in a synchronized cohort of MHC class I-specific thymocytes undergoing positive selection in situ. Transient elevations in intracellular calcium concentration ([Ca(2+)]i) and migratory pauses occurred throughout the first 24 h of positive selection, becoming progressively briefer and accompanied by a gradual shift in basal [Ca(2+)]i over time. Changes in chemokine-receptor expression and relocalization from the cortex to medulla occurred between 12 and 24 h after the initial encounter with positive-selecting ligands, a time frame at which the majority of thymocytes retain CD4 and CD8 expression and still require T-cell receptor (TCR) signaling to efficiently complete positive selection. Our results identify distinct phases in the positive selection of MHC class I-specific thymocytes that are distinguished by their TCR-signaling pattern and intrathymic location and provide a framework for understanding the multistep process of positive selection in the thymus.
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11
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Dynamic control of β1 integrin adhesion by the plexinD1-sema3E axis. Proc Natl Acad Sci U S A 2013; 111:379-84. [PMID: 24344262 DOI: 10.1073/pnas.1314209111] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Plexins and semaphorins comprise a large family of receptor-ligand pairs controlling cell guidance in nervous, immune, and vascular systems. How plexin regulation of neurite outgrowth, lymphoid trafficking, and vascular endothelial cell branching is linked to integrin function, central to most directed movement, remains unclear. Here we show that on developing thymocytes, plexinD1 controls surface topology of nanometer-scaled β1 integrin adhesion domains in cis, whereas its ligation by sema3E in trans regulates individual β1 integrin catch bonds. Loss of plexinD1 expression reduces β1 integrin clustering, thereby diminishing avidity, whereas sema3E ligation shortens individual integrin bond lifetimes under force to reduce stability. Consequently, both decreased expression of plexinD1 during developmental progression and a thymic medulla-emanating sema3E gradient enhance thymocyte movement toward the medulla, thus enforcing the orchestrated lymphoid trafficking required for effective immune repertoire selection. Our results demonstrate plexin-tunable molecular features of integrin adhesion with broad implications for many cellular processes.
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12
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Dzhagalov IL, Chen KG, Herzmark P, Robey EA. Elimination of self-reactive T cells in the thymus: a timeline for negative selection. PLoS Biol 2013; 11:e1001566. [PMID: 23700386 PMCID: PMC3660248 DOI: 10.1371/journal.pbio.1001566] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 04/11/2013] [Indexed: 01/22/2023] Open
Abstract
Two-photon microscopy and flow cytometry reveal the timing of thymocyte death and the surprisingly close coupling between cell death and phagocytosis during negative selection in thymic slices. The elimination of autoreactive T cells occurs via thymocyte apoptosis and removal by thymic phagocytes, but the sequence of events in vivo, and the relationship between thymocyte death and phagocytic clearance, are unknown. Here we address these questions by following a synchronized cohort of thymocytes undergoing negative selection within a three-dimensional thymic tissue environment, from the initial encounter with a negative selecting ligand to thymocyte death and clearance. Encounter with cognate peptide–MHC complexes results in rapid calcium flux and migratory arrest in auto-reactive thymocytes over a broad range of peptide concentrations, followed by a lag period in which gene expression changes occurred, but there was little sign of thymocyte death. Caspase 3 activation and thymocyte loss were first detectable at 2 and 3 hours, respectively, and entry of individual thymocytes into the death program occurred asynchronously over the next 10 hours. Two-photon time-lapse imaging revealed that thymocyte death and phagocytosis occurred simultaneously, often with thymocytes engulfed prior to changes in chromatin and membrane permeability. Our data provide a timeline for negative selection and reveal close coupling between cell death and clearance in the thymus. As an important safeguard against autoimmunity, T cells bearing autoreactive T cell antigen receptors are eliminated during their development in the thymus, a process known as negative selection. Although much is known about the molecular events involved in negative selection, surprisingly little is known about the dynamic aspects of the process. Here we examine a synchronized population of developing T cells (thymocytes) undergoing negative selection within three-dimensional living thymic tissue. We show that the initial encounter with negative selecting ligands results in migratory arrest, but in spite of this synchronous early response, individual thymocytes then undergo delayed and asynchronous entry into the death program between 2 and 12 hours thereafter. Using time-lapse two-photon imaging, we reveal that thymocyte death and the clearance of the dead cells invariably occur together, with many thymocytes already engulfed by a macrophage before the cell death-related changes in chromatin and membrane permeability are evident. These data provide a timeline of the major events during negative selection, and suggest close coupling between thymocyte death and clearance by macrophages.
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Affiliation(s)
- Ivan Lilyanov Dzhagalov
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Katherine Grace Chen
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Paul Herzmark
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Ellen A. Robey
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
- * E-mail:
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Halkias J, Melichar HJ, Taylor KT, Ross JO, Yen B, Cooper SB, Winoto A, Robey EA. Opposing chemokine gradients control human thymocyte migration in situ. J Clin Invest 2013; 123:2131-42. [PMID: 23585474 DOI: 10.1172/jci67175] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 02/15/2013] [Indexed: 12/23/2022] Open
Abstract
The ordered migration of thymocytes from the cortex to the medulla is critical for the appropriate selection of the mature T cell repertoire. Most studies of thymocyte migration rely on mouse models, but we know relatively little about how human thymocytes find their appropriate anatomical niches within the thymus. Moreover, the signals that retain CD4+CD8+ double-positive (DP) thymocytes in the cortex and prevent them from entering the medulla prior to positive selection have not been identified in mice or humans. Here, we examined the intrathymic migration of human thymocytes in both mouse and human thymic stroma and found that human thymocyte subsets localized appropriately to the cortex on mouse thymic stroma and that MHC-dependent interactions between human thymocytes and mouse stroma could maintain the activation and motility of DP cells. We also showed that CXCR4 was required to retain human DP thymocytes in the cortex, whereas CCR7 promoted migration of mature human thymocytes to the medulla. Thus, 2 opposing chemokine gradients control the migration of thymocytes from the cortex to the medulla. These findings point to significant interspecies conservation in thymocyte-stroma interactions and provide the first evidence that chemokines not only attract mature thymocytes to the medulla, but also play an active role in retaining DP thymocytes in the cortex prior to positive selection.
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Affiliation(s)
- Joanna Halkias
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, UC Berkeley, Berkeley, California 94720-3200, USA
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Dzhagalov I, Phee H. How to find your way through the thymus: a practical guide for aspiring T cells. Cell Mol Life Sci 2011; 69:663-82. [PMID: 21842411 DOI: 10.1007/s00018-011-0791-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 07/25/2011] [Accepted: 07/25/2011] [Indexed: 01/16/2023]
Abstract
Thymocytes must complete an elaborate developmental program in the thymus to ultimately generate T cells that express functional but neither harmful nor useless TCRs. Each developmental step coincides with dynamic relocation of the thymocytes between anatomically discrete thymic microenvironments, suggesting that thymocytes' migration is tightly regulated by their developmental status. Chemokines produced by thymic stromal cells and chemokine receptors on the thymocytes play an indispensable role in guiding developing thymocytes into the different microenvironments. In addition to long-range migration, chemokines increase the thymocytes' motility, enhancing their interaction with stromal cells. During the past several years, much progress has been made to determine the various signals that guide thymocytes on their journey within the thymus. In this review, we summarize the progress in identifying chemokines and other chemoattractant signals that direct intrathymic migration. Furthermore, we discuss the recent advances of two-photon microscopy in determining dynamic motility and interaction behavior of thymocytes within distinct compartments to provide a better understanding of the relationship between thymocyte motility and development.
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Affiliation(s)
- Ivan Dzhagalov
- LSA, Room 479, Department of Molecular and Cell Biology, Division of Immunology and Pathogenesis, University of California Berkeley, Berkeley, CA 94720-3200, USA.
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15
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Love PE, Bhandoola A. Signal integration and crosstalk during thymocyte migration and emigration. Nat Rev Immunol 2011; 11:469-77. [PMID: 21701522 PMCID: PMC3710714 DOI: 10.1038/nri2989] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The thymus produces self-tolerant functionally competent T cells. This process involves the import of multipotent haematopoietic progenitors that are then signalled to adopt the T cell fate. Expression of T cell-specific genes, including those encoding the T cell receptor (TCR), is followed by positive and negative selection and the eventual export of mature T cells. Significant progress has been made in elucidating the signals that direct progenitor cell trafficking to, within and out of the thymus. These advances are the subject of this Review, with a particular focus on the role of reciprocal cooperative and regulatory interactions between TCR- and chemokine receptor-mediated signalling.
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Affiliation(s)
- Paul E Love
- Eunice Kennedy Schriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA.
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Nitta T, Ohigashi I, Nakagawa Y, Takahama Y. Cytokine crosstalk for thymic medulla formation. Curr Opin Immunol 2010; 23:190-7. [PMID: 21194915 DOI: 10.1016/j.coi.2010.12.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 11/24/2010] [Accepted: 12/03/2010] [Indexed: 01/12/2023]
Abstract
The medullary microenvironment of the thymus plays a crucial role in the establishment of self-tolerance through the deletion of self-reactive thymocytes and the generation of regulatory T cells. Crosstalk or bidirectional signal exchanges between developing thymocytes and medullary thymic epithelial cells (mTECs) contribute to the formation of the thymic medulla. Recent studies have identified the molecules that mediate thymic crosstalk. Tumor necrosis factor superfamily cytokines, including RANKL, CD40L, and lymphotoxin, produced by positively selected thymocytes and lymphoid tissue inducer cells promote the proliferation and differentiation of mTECs. In return, CCR7 ligand chemokines produced by mTECs facilitate the migration of positively selected thymocytes to the medulla. The cytokine crosstalk between developing thymocytes and mTECs nurtures the formation of the thymic medulla and thereby regulates the establishment of self-tolerance.
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Affiliation(s)
- Takeshi Nitta
- Division of Experimental Immunology, Institute for Genome Research, University of Tokushima, Tokushima 770-8503, Japan
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Bunting MD, Comerford I, McColl SR. Finding their niche: chemokines directing cell migration in the thymus. Immunol Cell Biol 2010; 89:185-96. [PMID: 21135866 DOI: 10.1038/icb.2010.142] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
T lymphocytes are generated throughout life, arising from bone marrow-derived progenitors that complete an essential developmental process in the thymus. Thymic T cell education leads to the generation of a self-restricted and largely self-tolerant peripheral T-cell pool and is facilitated by interactions with thymic stromal cells residing in distinct supportive niches. The signals governing thymocyte precursor migration into the thymus, directing thymocyte navigation through thymic microenvironments and mature T-cell egress into circulation were, until recently, largely unknown, but presumed to be mediated to a large extent by chemokine signalling. Recent studies have now uncovered various specific functions for members of the chemokine superfamily in the thymus. These studies have not only revealed distinct but also in some cases overlapping roles for several chemokine family members in various thymocyte migration events and have also shown that homing and positioning of other cells in the thymus, such as dendritic cells and natural killer T cells is also chemokine-dependent. Here, we discuss current understanding of the role of chemokines in the thymus and highlight key future avenues for investigation in this field.
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Affiliation(s)
- Mark D Bunting
- Chemokine Biology Laboratory, Discipline of Microbiology and Immunology, The School of Molecular and Biomedical Science, The University of Adelaide, South Australia, Australia
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Morley SC, Wang C, Lo WL, Lio CWJ, Zinselmeyer BH, Miller MJ, Brown EJ, Allen PM. The actin-bundling protein L-plastin dissociates CCR7 proximal signaling from CCR7-induced motility. THE JOURNAL OF IMMUNOLOGY 2010; 184:3628-38. [PMID: 20194718 DOI: 10.4049/jimmunol.0903851] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Chemokines promote lymphocyte motility by triggering F-actin rearrangements and inducing cellular polarization. Chemokines can also enhance cell-cell adhesion and costimulate T cells. In this study, we establish a requirement for the actin-bundling protein L-plastin (LPL) in CCR7- and sphingosine-1-phosphate-mediated T cell chemotaxis using LPL(-/-) mice. Disrupted motility of mature LPL(-/-) thymocytes manifested in vivo as diminished thymic egress. Two-photon microscopy of LPL(-/-) lymphocytes revealed reduced velocity and motility in lymph nodes. Defective migration resulted from defective cellular polarization following CCR7 ligation, as CCR7 did not polarize to the leading edge in chemokine-stimulated LPL(-/-) T cells. However, CCR7 signaling to F-actin polymerization and CCR7-mediated costimulation was intact in LPL(-/-) lymphocytes. The differential requirement for LPL in CCR7-induced cellular adhesion and CCR7-induced motility allowed assessment of the contribution of CCR7-mediated motility to positive selection of thymocytes and lineage commitment. Results suggest that normal motility is not required for CCR7 to function in positive selection and lineage commitment. We thus identify LPL as a molecule critical for CCR7-mediated motility but dispensable for early CCR7 signaling. The requirement for actin bundling by LPL for polarization reveals a novel mechanism of regulating actin dynamics during T cell motility.
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Affiliation(s)
- Sharon Celeste Morley
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO 63110, USA
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CCR7-mediated migration of developing thymocytes to the medulla is essential for negative selection to tissue-restricted antigens. Proc Natl Acad Sci U S A 2009; 106:17129-33. [PMID: 19805112 DOI: 10.1073/pnas.0906956106] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Immature double-positive thymocytes are generated in the thymic cortex, and on positive selection, are induced to differentiate into mature single-positive thymocytes and relocate to the medulla. CCR7 is pivotal for cortex-to-medulla migration of positively selected thymocytes, and CCR7-mediated migration to the medulla is essential for establishing central tolerance, thereby, preventing tissue-specific autoimmunity. However, it was unclear how CCR7-mediated migration to the medulla affects the establishment of self-tolerance. Here, we show that the deletion of thymocytes specific for insulin-promoter-driven tissue-restricted antigens (TRAs) is significantly impaired in CCR7- or CCR7-ligand-deficient mice. These results indicate that CCR7-mediated migration to the medulla contributes to the negative selection of TRA-reactive thymocytes.
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Hawkins ED, Russell SM. Upsides and downsides to polarity and asymmetric cell division in leukemia. Oncogene 2009; 27:7003-17. [PMID: 19029941 DOI: 10.1038/onc.2008.350] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The notion that polarity regulators can act as tumor suppressors in epithelial cells is now well accepted. The function of these proteins in lymphocytes is less well explored, and their possible function as suppressors of leukemia has had little attention so far. We review the literature on lymphocyte polarity and the growing recognition that polarity proteins have an important function in lymphocyte function. We then describe molecular relationships between the polarity network and signaling pathways that have been implicated in leukemogenesis, which suggest mechanisms by which the polarity network might impact on leukemogenesis. We particularly focus on the possibility that disruption of polarity might alter asymmetric cell division (ACD), and that this might be a leukemia-initiating event. We also explore the converse possibility that leukemic stem cells might be produced or maintained by ACD, and therefore that Dlg, Scribble and Lgl might be important regulators of this process.
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Affiliation(s)
- E D Hawkins
- Immune Signalling Laboratory, Cancer Immunology, Research Division, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
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Ladi E, Schwickert TA, Chtanova T, Chen Y, Herzmark P, Yin X, Aaron H, Chan SW, Lipp M, Roysam B, Robey EA. Thymocyte-dendritic cell interactions near sources of CCR7 ligands in the thymic cortex. THE JOURNAL OF IMMUNOLOGY 2008; 181:7014-23. [PMID: 18981121 DOI: 10.4049/jimmunol.181.10.7014] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Little is known about the dynamics of the interactions between thymocytes and other cell types, as well as the spatiotemporal distribution of thymocytes during positive selection in the microenvironment of the cortex. We used two-photon laser scanning microscopy of the mouse thymus to visualize thymocytes and dendritic cells (DCs) and to characterize their interactions in the cortex. We show that thymocytes make frequent contacts with DCs in the thymic cortex and that these associations increase when thymocytes express T cell receptors that mediate positive selection. We also show that cortical DCs and the chemokine CCL21 expression are closely associated with capillaries throughout the cortex. The overexpression of the chemokine receptor CCR7 in thymocytes results in an increase in DC-thymocyte interactions, while the loss of CCR7 in the background of a positive-selecting TCR reduces the extent of DC-thymocyte interactions. These observations identify a vasculature-associated microenvironment within the thymic cortex that promotes interactions between DCs and thymocytes that are receiving positive selection signals.
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Affiliation(s)
- Ena Ladi
- Division of Immunology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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Nitta T, Murata S, Ueno T, Tanaka K, Takahama Y. Thymic microenvironments for T-cell repertoire formation. Adv Immunol 2008; 99:59-94. [PMID: 19117532 DOI: 10.1016/s0065-2776(08)00603-2] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Functionally competent immune system includes a functionally competent T-cell repertoire that is reactive to foreign antigens but is tolerant to self-antigens. The repertoire of T cells is primarily formed in the thymus through positive and negative selection of developing thymocytes. Immature thymocytes that undergo V(D)J recombination of T-cell antigen receptor (TCR) genes and that express the virgin repertoire of TCRs are generated in thymic cortex. The recent discovery of thymoproteasomes, a molecular complex specifically expressed in cortical thymic epithelial cells (cTEC), has revealed a unique role of cTEC in cuing the further development of immature thymocytes in thymic cortex, possibly by displaying unique self-peptides that induce positive selection. Cortical thymocytes that receive TCR-mediated positive selection signals are destined to survive for further differentiation and are induced to express CCR7, a chemokine receptor. Being attracted to CCR7 ligands expressed by medullary thymic epithelial cells (mTEC), CCR7-expressing positively selected thymocytes relocate to thymic medulla. The medullary microenvironment displays another set of unique self-peptides for trimming positively selected T-cell repertoire to establish self-tolerance, via promiscuous expression of tissue-specific antigens by mTEC and efficient antigen presentation by dendritic cells. Recent results demonstrate that tumor necrosis factor (TNF) superfamily ligands, including receptor activating NF-kappaB ligand (RANKL), CD40L, and lymphotoxin, are produced by positively selected thymocytes and pivotally regulate mTEC development and thymic medulla formation.
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Affiliation(s)
- Takeshi Nitta
- Division of Experimental Immunology, Institute for Genome Research, University of Tokushima, Tokushima 770-8503, Japan
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