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Shi B, Dong X, Ma Q, Sun S, Ma L, Yu J, Wang X, Pan J, He X, Su D, Yao X. The Usage of Human IGHJ Genes Follows a Particular Non-random Selection: The Recombination Signal Sequence May Affect the Usage of Human IGHJ Genes. Front Genet 2020; 11:524413. [PMID: 33363565 PMCID: PMC7753069 DOI: 10.3389/fgene.2020.524413] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 11/06/2020] [Indexed: 12/02/2022] Open
Abstract
The formation of the B cell receptor (BCR) heavy chain variable region is derived from the germline V(D)J gene rearrangement according to the “12/23” rule and the “beyond 12/23” rule. The usage frequency of each V(D)J gene in the peripheral BCR repertoires is related to the initial recombination, self-tolerance selection, and the clonal proliferative response. However, their specific differences and possible mechanisms are still unknown. We analyzed in-frame and out-of-frame BCR-H repertoires from human samples with normal physiological and various pathological conditions by high-throughput sequencing. Our results showed that IGHJ gene frequency follows a similar pattern which is previously known, where IGHJ4 is used at high frequency (>40%), IGHJ6/IGHJ3/IGHJ5 is used at medium frequencies (10∼20%), and IGH2/IGHJ1 is used at low frequency (<4%) under whether normal physiological or various pathological conditions. However, our analysis of the recombination signal sequences suggested that the conserved non-amer and heptamer and certain 23 bp spacer length may affect the initial IGHD-IGHJ recombination, which results in different frequencies of IGHJ genes among the initial BCR-H repertoire. Based on this “initial repertoire,” we recommend that re-evaluation and further investigation are needed when analyzing the significance and mechanism of IGHJ gene frequency in self-tolerance selection and the clonal proliferative response.
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Affiliation(s)
- Bin Shi
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, China.,School of Laboratory Medicine, Zunyi Medical University, Zunyi, China
| | - Xiaoheng Dong
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Qingqing Ma
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Suhong Sun
- Department of Breast Surgery, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Long Ma
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Jiang Yu
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Xiaomei Wang
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Juan Pan
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Xiaoyan He
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Danhua Su
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Xinsheng Yao
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
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2
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Li X, Gong L, Gu H. Regulation of immune system development and function by Cbl-mediated ubiquitination. Immunol Rev 2020; 291:123-133. [PMID: 31402498 DOI: 10.1111/imr.12789] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 05/30/2019] [Indexed: 12/24/2022]
Abstract
Ubiquitination is a form of posttranslational protein modification that affects the activity of target proteins by regulating their intracellular degradation, trafficking, localization, and association with other regulators. Recent studies have placed protein ubiquitination as an important regulatory mode to control immune system development, function, and pathogenesis. In this review, we will mainly update the research progress from our laboratory on the roles of the Cbl family of E3 ubiquitin ligases in the development and function of lymphocytes and non-lymphoid cells. In addition, we will highlight our current understanding of the mechanisms used by this family of proteins, especially Cbl and Cbl-b, to co-ordinately regulate the function of various receptors and transcription factors in the context of immune regulation and diseases.
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Affiliation(s)
- Xin Li
- Kisoji Biotechnologies, Laval, Quebec, Canada
| | - Liying Gong
- Institut de Recherches Cliniques de Montreàl, Montreal, Quebec, Canada.,Division of Experimental Medicine, McGill University, Montreal, Quebec, Canada
| | - Hua Gu
- Institut de Recherches Cliniques de Montreàl, Montreal, Quebec, Canada.,Division of Experimental Medicine, McGill University, Montreal, Quebec, Canada.,Department of Microbiology and Immunology, Department of Biochemistry and Molecular Medicine, University of Montreal, Montreal, Quebec, Canada
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3
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Lee SY, Stadanlick J, Kappes DJ, Wiest DL. Towards a molecular understanding of the differential signals regulating alphabeta/gammadelta T lineage choice. Semin Immunol 2010; 22:237-46. [PMID: 20471282 PMCID: PMC2906684 DOI: 10.1016/j.smim.2010.04.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Accepted: 04/14/2010] [Indexed: 10/19/2022]
Abstract
While insights into the molecular processes that specify adoption of the alphabeta and gammadelta fates are beginning to emerge, the basis for control of specification remains highly controversial. This review highlights the current models attempting to explain T lineage commitment. Recent observations support the hypothesis that the T cell receptor (TCR) provides instructive cues through differences in TCR signaling intensity and/or longevity. Accordingly, we review evidence addressing the importance of differences in signal strength/longevity, how signals differing in intensity/longevity may be generated, and finally how such signals modulate the activity of downstream effectors to promote the opposing developmental fates.
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MESH Headings
- Animals
- Cell Lineage
- Humans
- Models, Immunological
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Receptors, Antigen, T-Cell, gamma-delta/immunology
- Receptors, Antigen, T-Cell, gamma-delta/metabolism
- Signal Transduction
- T-Lymphocytes/cytology
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
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Affiliation(s)
- Sang-Yun Lee
- Immune Cell Development and Host Defense Program, Blood Cell Development and Cancer Keystone, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111
| | - Jason Stadanlick
- Immune Cell Development and Host Defense Program, Blood Cell Development and Cancer Keystone, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111
| | - Dietmar J. Kappes
- Immune Cell Development and Host Defense Program, Blood Cell Development and Cancer Keystone, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111
| | - David L. Wiest
- Immune Cell Development and Host Defense Program, Blood Cell Development and Cancer Keystone, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111
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4
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Nucleoprotein structure of the CD4 locus: implications for the mechanisms underlying CD4 regulation during T cell development. Proc Natl Acad Sci U S A 2008; 105:3873-8. [PMID: 18322012 DOI: 10.1073/pnas.0800810105] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The CD4 gene is regulated in a stage-specific manner during T cell development, being repressed in CD4(-)CD8(-) double-negative (DN) and CD8 cells, but expressed in CD4(+)CD8(+) double-positive (DP) and CD4 cells. Furthermore, the expression/repression pattern is reversible in developing (DN and DP) thymocytes, but irreversible in mature (CD4 and CD8) T cells. Here, we explored the molecular mechanisms underlying this complex mode of regulation by examining the nucleoprotein structure of the CD4 locus throughout T cell development and in DN cells lacking the CD4 silencer. In DN cells, the CD4 enhancer is preloaded with multiple transcription activators, but p300 recruitment is impaired by the silencer that is associated with the repressor Runx1. DP cells achieve high-level CD4 expression via a combination of CD4 derepression and true activation, but Runx1 remains bound to the silencer that retains an open chromatin configuration. In CD4 cells, Runx1 dissociates from the silencer that has become less accessible, and CD4 transcription appears to be achieved via a mechanism distinct from that operating in DP cells. In CD8 cells, the CD4 promoter becomes incorporated into heterochromatin-like structure. Our data shed light on the molecular basis of CD4 regulation and provide a conceptual framework for understanding how the same regulatory elements can mediate both reversible and irreversible CD4 regulation.
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5
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Abstract
Lateral compartmentalization of the plasma membrane into domains is a key feature of immune cell activation and subsequent immune effector functions. Here, we will review the high diversity of membrane domains, ranging from elementary lipid rafts, envisioned as dynamic and small domains (in the tens of nm), to relatively stable microm-scale membrane domains, which form the immunologic synapse of T lymphocytes. We will discuss the relationship between these different types of plasma membrane domains and how raft lipid- and protein-controlled interactions and cell biological processes cooperate to generate functional domains that mediate lymphocyte activity.
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Affiliation(s)
- Thomas Harder
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
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6
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Walsh CM, Luhrs KA, Arechiga AF. The "fuzzy logic" of the death-inducing signaling complex in lymphocytes. J Clin Immunol 2004; 23:333-53. [PMID: 14601642 DOI: 10.1023/a:1025313415487] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Receptors belonging to the tumor necrosis factor receptor family have long been thought to play an important role in the regulation of immunity. Although this family is composed of a large number of surface receptors that potentiate myriad functions in vivo, a subset is known to directly convey apoptotic signals. One such molecule belonging to this subset is CD95. Ligation of CD95 instigates the formation of a complex known as the "death-inducing signaling complex" or DISC, which is composed of molecules including FADD (Fas associated with death domain) and RIP (receptor-interacting kinase), as well as procaspases-8 and -10, and a caspase-8-like molecule that lacks proteolytic activity called c-FLIP. Although the DISC was initially thought to serve an exclusively proapoptotic role, humans and mice with defects in various components of this complex demonstrate a variety of developmental and hematopoietic defects that are not apparently due to aberrant apoptosis. These findings paint a far more complex picture of the numerous components of the DISC, and provide evidence that these complexes serve nonapoptotic functions. Herein, we summarize the experimental evidence challenging the notion that the DISC imparts an exclusively apoptotic function and provide hypotheses to account for these alternative roles. Rather than operating as a binary system, we propose that the DISCs formed around various DRs transduce signals leading to a variety of cellular fates.
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Affiliation(s)
- Craig M Walsh
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900, USA.
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7
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Sato T, Ito R, Nunomura S, Ohno SI, Hayashi K, Satake M, Habu S. Requirement of transcription factor AML1 in proliferation of developing thymocytes. Immunol Lett 2003; 89:39-46. [PMID: 12946863 DOI: 10.1016/s0165-2478(03)00103-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Although the transcription factor AML1/Runx1 is known to be essential for definitive hematopoiesis, its role in T cell differentiation is not well understood. In this study, we investigated the functions of AML1 in the early stage of thymocyte differentiation. For this, we crossed AML1 dominant interfering form (Runt)-transgenic mice with TCR-transgenic mice, and demonstrated the decrease of CD4+8+ (DP) thymocyte cell number although their proportion was not reduced. Reaggregation culture system for thymocytes of (RuntxTCR) double transgenic mice, in which the rate of de novo transition from DN cells to the DP stage can be estimated, showed that the cell division during the DN-to-DP transition is impaired without significant cell death. These results indicate that AML1 is involved in thymocyte differentiation by controlling cell proliferation.
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Affiliation(s)
- Takehito Sato
- Department of Immunology, Tokai University School of Medicine, Boseidai, Isehara, Kanagawa 259-1193, Japan
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8
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Abstract
Apoptotic cell death plays a critical role in the development and functioning of the immune system. During differentiation, apoptosis weeds out lymphocytes lacking useful antigen receptors and those expressing dangerous ones. Lymphocyte death is also involved in limiting the magnitude and duration of immune responses to infection. In this review, we describe the role of the Bcl-2 protein family, and to a lesser extent that of death receptors (members of the tumor necrosis factor receptor family with a death domain), in the control of lymphoid and myeloid cell survival. We also consider the pathogenic consequences of failure of apoptosis in the immune system.
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Affiliation(s)
- Vanessa S Marsden
- Molecular Genetics of Cancer Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
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9
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Chi TH, Wan M, Lee PP, Akashi K, Metzger D, Chambon P, Wilson CB, Crabtree GR. Sequential roles of Brg, the ATPase subunit of BAF chromatin remodeling complexes, in thymocyte development. Immunity 2003; 19:169-82. [PMID: 12932351 DOI: 10.1016/s1074-7613(03)00199-7] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
T cells develop through distinct stages directed by a series of signals. We explored the roles of SWI/SNF-like BAF chromatin remodeling complexes in this process by progressive deletion of the ATPase subunit, Brg, through successive stages of early T cell development. Brg-deficient cells were blocked at each of the developmental transitions examined. Bcl-xL overexpression suppressed cell death without relieving the developmental blockades, leading to the accumulation of Brg-deleted cells that were unexpectedly cell cycle arrested. These defects resulted partly from the disruptions of pre-TCR and potentially Wnt signaling pathways controlling the expression of genes such as c-Kit and c-Myc critical for continued development. Our studies indicate that BAF complexes dynamically remodel chromatin to propel sequential developmental transitions in response to external signals.
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Affiliation(s)
- Tian H Chi
- Departments of Pathology and Developmental Biology, Howard Hughes Medical Institute, Stanford University Medical School, Palo Alto, California 94305, USA
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10
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Taniuchi I, Osato M, Egawa T, Sunshine MJ, Bae SC, Komori T, Ito Y, Littman DR. Differential requirements for Runx proteins in CD4 repression and epigenetic silencing during T lymphocyte development. Cell 2002; 111:621-33. [PMID: 12464175 DOI: 10.1016/s0092-8674(02)01111-x] [Citation(s) in RCA: 600] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
T lymphocytes differentiate in discrete stages within the thymus. Immature thymocytes lacking CD4 and CD8 coreceptors differentiate into double-positive cells (CD4(+)CD8(+)), which are selected to become either CD4(+)CD8(-)helper cells or CD4(-)CD8(+) cytotoxic cells. A stage-specific transcriptional silencer regulates expression of CD4 in both immature and CD4(-)CD8(+) thymocytes. We show here that binding sites for Runt domain transcription factors are essential for CD4 silencer function at both stages, and that different Runx family members are required to fulfill unique functions at each stage. Runx1 is required for active repression in CD4(-)CD8(-) thymocytes whereas Runx3 is required for establishing epigenetic silencing in cytotoxic lineage thymocytes. Runx3-deficient cytotoxic T cells, but not helper cells, have defective responses to antigen, suggesting that Runx proteins have critical functions in lineage specification and homeostasis of CD8-lineage T lymphocytes.
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Affiliation(s)
- Ichiro Taniuchi
- Howard Hughes Medical Institute, Molecular Pathogenesis Program, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA.
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11
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Szondy Z, Tóth R, Szegezdi E, Reichert U, Ancian P, Fésüs L. Cell death in HIV pathogenesis and its modulation by retinoids. Ann N Y Acad Sci 2001; 946:95-107. [PMID: 11762998 DOI: 10.1111/j.1749-6632.2001.tb03905.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Patients infected with the human immunodeficiency virus exhibit a progressive decline in the CD4 T-cell number, resulting in immunodeficiency and increased susceptibility to opportunistic infections and malignancies. Although CD4 T cell production is impaired in patients infected with HIV, there is now increasing evidence that the primary basis of T cell depletion is accelerated apoptosis of CD4 and CD8 T cells. The rate of lymphocyte apoptosis in HIV infection correlates inversely with the progression of the disease: it is low in long-term progressors and in patients undergoing highly active antiretroviral therapy. Interestingly, only a minor fraction of apoptotic lymphocytes are infected by HIV, indicating that the enhanced apoptosis does not necessarily always serve to remove the HIV+ cells and results from mechanisms other than direct infection. Thus, understanding and influencing the mechanisms of HIV-associated lymphocyte apoptosis may lead to new therapies for HIV disease. In this paper the potential effects of retinoids on CD4 T cell apoptosis is discussed.
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Affiliation(s)
- Z Szondy
- Department of Biochemistry and MolecularBiology, Medical and Health Science Center, University of Debrecen, Hungary
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12
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Su DM, Manley NR. Hoxa3 and pax1 transcription factors regulate the ability of fetal thymic epithelial cells to promote thymocyte development. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:5753-60. [PMID: 10820253 DOI: 10.4049/jimmunol.164.11.5753] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Thymocyte maturation into T cells depends on interactions between thymocytes and thymic epithelial cells. In this study, we show that mutations in two transcription factors, Hoxa3 and Pax1, act synergistically to cause defective thymic epithelial cell development, resulting in thymic ectopia and hypoplasia. Hoxa3+/-Pax1-/- compound mutant mice exhibited more severe thymus defects than Pax1-/- single mutants. Fetal liver adoptive transfer experiments revealed that the defect resided in radio-resistant stromal cells and not in hematopoietic cells. Compound mutants have fewer MHC class II+ epithelial cells, and the level of MHC expression detected was lower. Thymic epithelial cells in these mutants have reduced ability to promote thymocyte development, causing a specific block in thymocyte maturation at an early stage that resulted in a dramatic reduction in the number of CD4+8+ thymocytes. This phenotype was accompanied by increased apoptosis of CD4+8+ thymocytes and their immediate precursors, CD44-25-(CD3-4-8-) cells. Our results identify a transcriptional regulatory pathway required for thymic epithelial cell development and define multiple roles for epithelial cell regulation of thymocyte maturation at the CD4-8- to CD4+8+ transition.
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MESH Headings
- Adjuvants, Immunologic/genetics
- Adjuvants, Immunologic/physiology
- Animals
- Antigens, CD/biosynthesis
- Antigens, Differentiation, T-Lymphocyte/biosynthesis
- CD4-CD8 Ratio
- Cell Death/genetics
- Cell Death/immunology
- Cell Differentiation/genetics
- Cell Differentiation/immunology
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/physiology
- Embryonic and Fetal Development/genetics
- Embryonic and Fetal Development/immunology
- Epithelial Cells/immunology
- Epithelial Cells/metabolism
- Gene Deletion
- Histocompatibility Antigens Class II/biosynthesis
- Homeodomain Proteins/genetics
- Homeodomain Proteins/physiology
- Lectins, C-Type
- Lymphocyte Depletion
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Paired Box Transcription Factors
- Phenotype
- Receptors, Antigen, T-Cell/biosynthesis
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- Thymus Gland/cytology
- Thymus Gland/embryology
- Thymus Gland/immunology
- Thymus Gland/metabolism
- Transcription Factors/genetics
- Transcription Factors/physiology
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Affiliation(s)
- D M Su
- Institute of Molecular Medicine and Genetics and Department of Pediatrics, Medical College of Georgia, Augusta, GA 30912, USA.
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13
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Michie AM, Trop S, Wiest DL, Zúñiga-Pflücker JC. Extracellular signal-regulated kinase (ERK) activation by the pre-T cell receptor in developing thymocytes in vivo. J Exp Med 1999; 190:1647-56. [PMID: 10587355 PMCID: PMC2195734 DOI: 10.1084/jem.190.11.1647] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/1999] [Accepted: 09/29/1999] [Indexed: 12/17/2022] Open
Abstract
The first checkpoint in T cell development occurs between the CD4(-)CD8(-) and CD4(+)CD8(+) stages and is associated with formation of the pre-T cell receptor (TCR). The signaling mechanisms that drive this progression remain largely unknown. Here, we show that extracellular signal-regulated kinases (ERKs)-1/2 are activated upon engagement of the pre-TCR. Using a novel experimental system, we demonstrate that expression of the pre-TCR by developing thymocytes induces ERK-1/2 activation within the thymus. In addition, the activation of this pre-TCR signaling cascade is mediated through Lck. These findings directly link pre-TCR complex formation with specific downstream signaling components in vivo.
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Affiliation(s)
- Alison M. Michie
- Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Sébastien Trop
- Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
- Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada
| | - David L. Wiest
- Division of Basic Sciences, Immunobiology Working Group, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111
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14
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Affiliation(s)
- S Desiderio
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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15
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Cleverley S, Henning S, Cantrell D. Inhibition of Rho at different stages of thymocyte development gives different perspectives on Rho function. Curr Biol 1999; 9:657-60. [PMID: 10375531 DOI: 10.1016/s0960-9822(99)80289-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Development of thymocytes can be staged according to the levels of expression of the cell-surface markers CD4, CD8, CD44, CD25 and CD2. Thymocyte development is regulated by a complex signalling network [1], one component of which is the GTPase Rho. The bacterial enzyme C3 transferase from Clostridium botulinum selectively ADP-ribosylates Rho in its effector-binding domain and thereby abolishes its biological function [2,3]. To explore the function of Rho in thymocyte development, we previously used the proximal promoter of the gene encoding the Src-family kinase p56lck to make transgenic mice that selectively express C3 transferase in the thymus [4,6]. In these mice, which lack Rho function from the earliest thymocyte stages, thymocyte numbers are reduced by approximately 50- to 100-fold. Here, we describe transgenic mice that express C3 transferase under the control of the locus control region (LCR) of the CD2 gene; this regulatory element drives expression at a later stage of thymocyte development than the lck proximal promoter [7]. In these mice, thymocyte numbers were also reduced by 50- to 100-fold, but unlike the lck-C3 mice, in which the reduction predominantly results from defects in cell survival of CD25(+) thymocyte progenitors, the CD2-C3 transgenic mice had a pre-T-cell differentiation block at the CD25(+) stage after rearrangement of the T-cell receptor (TCR) beta chains. Analysis of CD2-C3 mice demonstrated that Rho acts as an intracellular switch for TCR beta selection, the critical thymic-differentiation checkpoint. These results show that Rho-mediated survival signals for CD25(+) pre-T cells are generated by the extracellular signals that act on earlier thymocyte precursors and also that temporal cell-type-specific elimination of Rho can reveal different functions of this GTPase in vivo.
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Affiliation(s)
- S Cleverley
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, 44 Lincoln's Inn Fields, London, WC2A 3PX, UK.
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16
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Grassi F, Barbier E, Porcellini S, von Boehmer H, Cazenave PA. Surface Expression and Functional Competence of CD3-Independent TCR ζ-Chains in Immature Thymocytes. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.5.2589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
In recombinase-deficient (RAG-2−/−) mice, double-negative thymocytes can be stimulated to proliferate and differentiate by anti-CD3 Abs. CD3 molecules are expressed on the surface of these cells in association with calnexin. In this study, we show that ζ-chains can be recovered as phosphorylated proteins in association with phosphorylated ZAP-70 from anti-CD3-stimulated RAG-2−/− thymocytes, even though they are not demonstrably associated with the CD3/calnexin complex. The lack of a physical association of ζ dimers with the CD3 complex in RAG-2−/− thymocytes and also in a pre-TCR-expressing cell line, as well as the efficient association of ζ dimers with ZAP-70 in the RAG-2−/− thymocytes, suggest that these ζ-chain dimers could contribute to pre-TCR signaling. This idea is supported by the finding that in RAG-2−/− ζ-deficient thymocytes, ZAP-70 and p120cbl were only weakly phosphorylated.
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Affiliation(s)
- Fabio Grassi
- *Dipartimento di Biologia e Genetica per le Scienze Mediche, Università di Milano at Department of Biological and Technological Research, San Raffaele Scientific Institute (HSR), Milan, Italy
- †Unité d’Immunochimie Analytique, Département d’Immunologie, Institut Pasteur, Unité de Recherche Associée, Centre National de la Recherche Scientifique D1961, and Université Pierre et Marie Curie, Paris, France; and
| | - Eliane Barbier
- †Unité d’Immunochimie Analytique, Département d’Immunologie, Institut Pasteur, Unité de Recherche Associée, Centre National de la Recherche Scientifique D1961, and Université Pierre et Marie Curie, Paris, France; and
| | - Simona Porcellini
- *Dipartimento di Biologia e Genetica per le Scienze Mediche, Università di Milano at Department of Biological and Technological Research, San Raffaele Scientific Institute (HSR), Milan, Italy
| | - Harald von Boehmer
- ‡Institut Necker, Institut National de la Santé et Recherche Medicale, U373, Paris, France
| | - Pierre-André Cazenave
- †Unité d’Immunochimie Analytique, Département d’Immunologie, Institut Pasteur, Unité de Recherche Associée, Centre National de la Recherche Scientifique D1961, and Université Pierre et Marie Curie, Paris, France; and
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17
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Sato T, Kishihara K, Mak TW, Habu S. Beta-selection of immature thymocytes is less dependent on CD45 tyrosinephosphatase. Immunol Lett 1998; 64:133-8. [PMID: 9870664 DOI: 10.1016/s0165-2478(98)00094-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Tyrosine kinase p56lck plays a pivotal role in beta-selection from CD4-8- (DN) to CD4+8+ (DP) developing pathway, but it is unclear how CD45 transmembrane tyrosinephosphatase is involved in this process although CD45 activates p56lck by dephosphorylating its tyrosine-505. To analyze this issue, we produced double mutant mice of T-cell receptor transgenic mice (TCR-Tg) or RAG-2 knock out mice backcrossed with either p56lck or CD45 knock out mice. In TCR-Tg, CD25+DN thymocytes almost disappeared and CD25-44-DN cells of further developing stage increased, implying that all DN thymocytes can undergo beta-selection due to the expression of functionally rearranged TCR-beta on CD25+ DN thymocytes. However, CD25+ thymocytes increased in DN stage when TCR-Tg were backcrossed with p56lck deficient mice but not with CD45 deficient mice. Similarly, DP thymocyte induction with CD25+ cell reduction in RAG-2 knock out mice by injection of anti-CD3 mAb was inhibited in p56lck deficient but not in CD45 deficient mice. This suggests that CD45 is dispensable for beta-selection though p56lck is required.
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Affiliation(s)
- T Sato
- Department of Immunology, Tokai University School of Medicine, Isehara, Kanagawa, Japan
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18
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Saint-Ruf C, Lechner O, Feinberg J, von Boehmer H. Genomic structure of the human pre-T cell receptor alpha chain and expression of two mRNA isoforms. Eur J Immunol 1998; 28:3824-31. [PMID: 9842925 DOI: 10.1002/(sici)1521-4141(199811)28:11<3824::aid-immu3824>3.0.co;2-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The pre-TCR, which is minimally composed of the TCRbeta chain, the pre-Talpha chain, and the CD3 complex, regulates early T cell development. The pre-Talpha chain is a 33-kDa type I transmembrane glycoprotein with an extracellular part similar to the constant domain of the immunoglobulin supergene family. We have sequenced (11 kb) the human pTalpha gene, which like the murine pTalpha gene consists of four exons: exon 1 encodes the 5' untranslated region, the leader peptide and the first three amino acids of the mature protein, exon 2 the extracellular immunoglobulin (Ig)-like domain, exon 3 a 15-amino acid peptide including a cysteine required for heterodimerization with TCRbeta, exon 4 the transmembrane region, the cytoplasmic tail and the 3' untranslated sequence. The human pTalpha gene is located on chromosome 6p21.3, close to the HLA-A locus. Reverse transcription-PCR studies with human thymus and leukemic cells showed that alternative splicing produces a shorter pTalpha isoform, which lacks the Ig-like domain but contains the transmembrane elements and the extracytoplasmic cystein and which could thus permit pairing with TCRbeta chain and association with CD3 molecules. The conserved splice sites suggest a yet ill-defined biological function of the short pTalpha protein.
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MESH Headings
- Humans
- Precipitin Tests
- Protein Precursors/genetics
- RNA Splicing
- RNA, Messenger/analysis
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Tumor Cells, Cultured
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Affiliation(s)
- C Saint-Ruf
- Institut Necker, INSERM Unité 373, Paris, France.
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19
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Carlyle JR, Zúñiga-Pflücker JC. Lineage commitment and differentiation of T and natural killer lymphocytes in the fetal mouse. Immunol Rev 1998; 165:63-74. [PMID: 9850852 DOI: 10.1111/j.1600-065x.1998.tb01230.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
T cells and natural killer (NK) cells are presumed to share a common intrathymic precursor. The development of conventional alpha beta T lymphocytes begins within the early fetal thymus, after the colonization of multipotent CD117+ precursors. Irrevocable commitment to the T lineage is marked by thymus-induced expression of CD25. However, the contribution of the fetal thymus to NK lineage commitment and differentiation remains largely unappreciated. Recently, we demonstrated that the development of functional mouse NK cells occurs first in the fetal thymus. Moreover, the appearance of mature fetal thymic NK cells (NK1.1+/CD117-) is preceded by a thymus-induced developmental stage (NK1.1+/CD117+) that marks lineage commitment of multipotent hematopoietic precursors to the T and NK-cell fates. Commitment to the T/NK bipotent stage is induced by fetal thymic stroma, but is not thymus dependent. Recent data indicate that CD90+/CD117lo fetal blood prothymocytes exhibit NK lineage potential and are phenotypically and functionally identical to fetal thymic NK1.1+/CD117+ progenitors. This finding also indicates that full commitment of circulating precursors to the T-cell lineage occurs after thymus colonization. In this review, we discuss recent insights into the cellular and molecular events involved in fetal mouse T and NK lineage commitment and differentiation to unipotent progenitors.
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Affiliation(s)
- J R Carlyle
- Department of Immunology, University of Toronto, Ontario, Canada.
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20
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Schmidt T, Karsunky H, Rödel B, Zevnik B, Elsässer HP, Möröy T. Evidence implicating Gfi-1 and Pim-1 in pre-T-cell differentiation steps associated with beta-selection. EMBO J 1998; 17:5349-59. [PMID: 9736613 PMCID: PMC1170861 DOI: 10.1093/emboj/17.18.5349] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
After rearrangement of the T-cell receptor (TCR) beta-locus, early CD4(-)/CD8(-) double negative (DN) thymic T-cells undergo a process termed 'beta-selection' that allows the preferential expansion of cells with a functional TCR beta-chain. This process leads to the formation of a rapidly cycling subset of DN cells that subsequently develop into CD4(+)/CD8(+) double positive (DP) cells. Using transgenic mice that constitutively express the zinc finger protein Gfi-1 and the serine/threonine kinase Pim-1, we found that the levels of both proteins are important for the correct development of DP cells from DN precursors at the stage where 'beta-selection' occurs. Analysis of the CD25(+)/CD44(-,lo) DN subpopulation from these animals revealed that Gfi-1 inhibits and Pim-1 promotes the development of larger beta-selected cycling cells ('L subset') from smaller resting cells ('E subset') within this subpopulation. We conclude from our data that both proteins, Pim-1 and Gfi-1, participate in the regulation of beta-selection-associated pre-T-cell differentiation in opposite directions and that the ratio of both proteins is important for pre-T-cells to pass the 'E' to 'L' transition correctly during beta-selection.
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Affiliation(s)
- T Schmidt
- Institut für Zellbiologie (Tumorforschung), IFZ, Universitätsklinikum Essen, Virchowstrasse 173, D-45122 Essen, Germany
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21
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22
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Malek SN, Dordai DI, Reim J, Dintzis H, Desiderio S. Malignant transformation of early lymphoid progenitors in mice expressing an activated Blk tyrosine kinase. Proc Natl Acad Sci U S A 1998; 95:7351-6. [PMID: 9636152 PMCID: PMC22613 DOI: 10.1073/pnas.95.13.7351] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The intracellular signals governing cellular proliferation and developmental progression during lymphocyte development are incompletely understood. The tyrosine kinase Blk is expressed preferentially in the B lineage, but its function in B cell development has been largely unexplored. We have generated transgenic mice expressing constitutively active Blk [Blk(Y495F)] in the B and T lymphoid compartments. Expression of Blk(Y495F) in the B lineage at levels similar to that of endogenous Blk induced B lymphoid tumors of limited clonality, whose phenotypes are characteristic of B cell progenitors at the proB/preB-I to preB-II transition. Expression of constitutively active Blk in the T lineage resulted in the appearance of clonal, thymic lymphomas composed of intermediate single positive cells. Taken together, these results indicate that specific B and T cell progenitor subsets are preferentially susceptible to transformation by Blk(Y495F) and suggest a role for Blk in the control of proliferation during B cell development.
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Affiliation(s)
- S N Malek
- Department of Molecular Biology and Genetics and Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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23
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Wang H, Diamond RA, Rothenberg EV. Cross-lineage expression of Ig-beta (B29) in thymocytes: positive and negative gene regulation to establish T cell identity. Proc Natl Acad Sci U S A 1998; 95:6831-6. [PMID: 9618498 PMCID: PMC22652 DOI: 10.1073/pnas.95.12.6831] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Developmental commitment involves activation of lineage-specific genes, stabilization of a lineage-specific gene expression program, and permanent inhibition of inappropriate characteristics. To determine how these processes are coordinated in early T cell development, the expression of T and B lineage-specific genes was assessed in staged subsets of immature thymocytes. T lineage characteristics are acquired sequentially, with germ-line T cell antigen receptor-beta transcripts detected very early, followed by CD3epsilon and terminal deoxynucleotidyl transferase, then pTalpha, and finally RAG1. Only RAG1 expression coincides with commitment. Thus, much T lineage gene expression precedes commitment and does not depend on it. Early in the course of commitment to the T lineage, thymocytes lose the ability to develop into B cells. To understand how this occurs, we also examined expression of well defined B lineage-specific genes. Although lambda5 and Ig-alpha are not expressed, the mu 0 and I mu transcripts from the unrearranged IgH locus are expressed early, in distinct patterns, then repressed just before RAG1 expression. By contrast, RNA encoding the B cell receptor component Ig-beta was found to be transcribed in all immature thymocyte subpopulations and throughout most thymocyte differentiation. Ig-beta expression is down-regulated only during positive selection of CD4(+)CD8(-) cells. Thus several key participants in the B cell developmental program are expressed in non-B lineage-committed cells, and one is maintained even through commitment to an alternative lineage, and repressed only after extensive T lineage differentiation. The results show that transcriptional activation of "lymphocyte-specific" genes can occur in uncommitted precursors, and that T lineage commitment is a composite of distinct positive and negative regulatory events.
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Affiliation(s)
- H Wang
- Stowers Institute for Medical Research, California Institute of Technology, Pasadena, CA 91125, USA
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24
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Nadel B, Tang A, Escuro G, Lugo G, Feeney AJ. Sequence of the spacer in the recombination signal sequence affects V(D)J rearrangement frequency and correlates with nonrandom Vkappa usage in vivo. J Exp Med 1998; 187:1495-503. [PMID: 9565641 PMCID: PMC2212273 DOI: 10.1084/jem.187.9.1495] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/1998] [Revised: 02/27/1998] [Indexed: 11/04/2022] Open
Abstract
Functional variable (V), diversity (D), and joining (J) gene segments contribute unequally to the primary repertoire. One factor contributing to this nonrandom usage is the relative frequency with which the different gene segments rearrange. Variation from the consensus sequence in the heptamer and nonamer of the recombination signal sequence (RSS) is therefore considered a major factor affecting the relative representation of gene segments in the primary repertoire. In this study, we show that the sequence of the spacer is also a determinant factor contributing to the frequency of rearrangement. Moreover, the effect of the spacer on recombination rates of various human Vkappa gene segments in vitro correlates with their frequency of rearrangement in vivo in pre-B cells and with their representation in the peripheral repertoire.
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Affiliation(s)
- B Nadel
- The Scripps Research Institute, Department of Immunology, La Jolla, California 92037, USA
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25
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Fleck M, Zhou T, Tatsuta T, Yang P, Wang Z, Mountz JD. Fas/Fas Ligand Signaling During Gestational T Cell Development. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.160.8.3766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Most thymocytes express high levels of Fas Ag (Apo-1/CD95); however, the role of Fas/Fas ligand-mediated apoptosis in thymocyte development remains unclear. During gestational development of thymocytes in C57BL/6(B6) +/+ mice, the highest levels of Fas ligand mRNA and Fas ligand protein expression were detected at gestational day (GD) 15, and there was a ninefold decrease in Fas ligand mRNA expression between GD 15 and 17 accompanied by a sixfold increase in Fas mRNA. Apoptotic thymocytes were first detected in the medulla at GD 15, and increasing numbers of cortical clusters and scattered, single apoptotic cells were present on GD 16 and 17. Thus, early apoptosis correlated with high expression of Fas ligand. High levels of Fas ligand mRNA were maintained throughout gestational development in thymocytes of Fas-deficient B6-lpr/lpr mice, but cortical clusters and scattered apoptotic cells were decreased relative to B6 +/+ mice before GD 17. Kinetic analysis of fetal thymic organ cultures treated with anti-Fas Ab demonstrated that thymocytes become sensitive to Fas-mediated apoptosis during the transition from the CD4−CD8− to the CD4+CD8+ phenotype. More mature CD4+CD8+ thymocytes and CD4+ and CD8+ thymocytes became resistant to Fas-mediated apoptosis after GD 17, despite high expression of Fas. However, low avidity engagement of the TCR on Fas-sensitive CD4+CD8+ thymocytes before GD 17 induced resistance to Fas-mediated apoptosis. The present results indicate that Fas plays a critical role in mediating apoptosis during early gestational thymocyte development and that thymocytes that receive a survival signal through TCR/CD3 become resistant to Fas-mediated apoptosis.
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Affiliation(s)
- Martin Fleck
- *The University of Regensburg, Department of Medicine I, Regensburg, Germany
- †The University of Alabama at Birmingham, Department of Medicine, Division of Clinical Immunology and Rheumatology, and the Veterans Administration Medical Center, Birmingham, AL 35294; and
| | - Tong Zhou
- †The University of Alabama at Birmingham, Department of Medicine, Division of Clinical Immunology and Rheumatology, and the Veterans Administration Medical Center, Birmingham, AL 35294; and
| | - Toru Tatsuta
- †The University of Alabama at Birmingham, Department of Medicine, Division of Clinical Immunology and Rheumatology, and the Veterans Administration Medical Center, Birmingham, AL 35294; and
- ‡Sankyo Co. Ltd., Tokyo, Japan
| | - Pingar Yang
- †The University of Alabama at Birmingham, Department of Medicine, Division of Clinical Immunology and Rheumatology, and the Veterans Administration Medical Center, Birmingham, AL 35294; and
| | - Zheng Wang
- †The University of Alabama at Birmingham, Department of Medicine, Division of Clinical Immunology and Rheumatology, and the Veterans Administration Medical Center, Birmingham, AL 35294; and
| | - John D. Mountz
- †The University of Alabama at Birmingham, Department of Medicine, Division of Clinical Immunology and Rheumatology, and the Veterans Administration Medical Center, Birmingham, AL 35294; and
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26
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Walsh CM, Wen BG, Chinnaiyan AM, O'Rourke K, Dixit VM, Hedrick SM. A role for FADD in T cell activation and development. Immunity 1998; 8:439-49. [PMID: 9586634 DOI: 10.1016/s1074-7613(00)80549-x] [Citation(s) in RCA: 204] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
FADD is a cytoplasmic adapter molecule that links the family of death receptors to the activation of caspases during apoptosis. We have produced transgenic mice expressing a dominantly interfering mutant of FADD, lacking the caspase-dimerizing death effector domain, as well as mice overexpressing the poxvirus serpin, CrmA, an inhibitor of caspases downstream of FADD. While thymocytes from either line of mice were completely protected from CD95-dependent cytotoxicity, neither transgene afforded protection from apoptosis induced during thymocyte selection and neither led to the lymphoproliferative disorders associated with deficiencies in CD95. However, in FADD dominant negative (FADDdd) mice, early thymocyte development was retarded and peripheral lymphocyte pools were devoid of normal populations of T cells. We show that thymocytes and peripheral T cells from FADDdd display signaling anomalies, implying that FADD plays a previously uncharacterized role in T cell development and activation.
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Affiliation(s)
- C M Walsh
- Department of Biology and the Cancer Center, The University of California, San Diego, La Jolla 92093-0687, USA
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27
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Chattopadhyay S, Whitehurst CE, Schwenk F, Chen J. Biochemical and Functional Analyses of Chromatin Changes at the TCR-β Gene Locus During CD4−CD8− to CD4+CD8+ Thymocyte Differentiation. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.160.3.1256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Allelic exclusion is the process wherein lymphocytes express Ag receptors from only one of two possible alleles, and is effected through a feedback inhibition of further rearrangement of the second allele. The feedback signal is thought to cause chromatin changes that block accessibility of the second allele to the recombinase. To identify the putative chromatin changes associated with allelic exclusion, we assayed for DNase I hypersensitivity, DNA methylation, and transcription in 100 kb of the TCR-β locus. Contrary to current models, we identified chromatin changes indicative of an active and accessible locus associated with the occurrence of allelic exclusion. Of 11 DNase I hypersensitive sites identified, 3 were induced during CD4−CD8− to CD4+CD8+ thymocyte differentiation, and demethylation and increased germline transcription of the locus were evident. We further examined the role of the most prominently induced site near the TCR-β enhancer (Eβ) in allelic exclusion by targeted mutagenesis. Two other sites were also examined in New Zealand White (NZW) mice that have a natural deletion in the TCR-β locus. TCR-β gene recombination and allelic exclusion were normal in both mutant mice, negating dominant roles for the three hypersensitive sites in the control of allelic exclusion. The data suggest that alternative cis-regulatory elements, perhaps contained in the Eβ enhancer and/or in the upstream Vβ region, are involved in the control of TCR-β allelic exclusion.
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Affiliation(s)
- Samit Chattopadhyay
- *Center for Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139; and
| | - Charles E. Whitehurst
- *Center for Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139; and
| | - Frieder Schwenk
- †Institute for Genetics, University of Cologne, Cologne, Germany
| | - Jianzhu Chen
- *Center for Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139; and
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28
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Sharp LL, Schwarz DA, Bott CM, Marshall CJ, Hedrick SM. The influence of the MAPK pathway on T cell lineage commitment. Immunity 1997; 7:609-18. [PMID: 9390685 DOI: 10.1016/s1074-7613(00)80382-9] [Citation(s) in RCA: 192] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
During development, progenitor thymocytes differentiate into either CD4 or CD8 T cells, and this fate decision depends on the specificity of the T cell antigen receptor (TCR) for MHC class II or class I molecules. Based on the mechanisms of fate specification known for simple metazoan organisms, we sought to determine whether the extracellular signal-related kinases (ERKs) play a role in T cell differentiation and lineage commitment. Using a dominant gain-of-function mutant of the erk2 gene, we show that differentiation into the CD4 lineage is favored. We also show that, conversely, the addition of a pharmacological inhibitor of the ERK pathway favors differentiation into the CD8 lineage. We present a quantitative selection model that incorporates these results as well as those of recent reports on the role of Notch in T cell lineage specification.
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Affiliation(s)
- L L Sharp
- The Department of Biology and the Cancer Center, University of California, San Diego, La Jolla 92093-0687, USA
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29
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Shibata S, Asano T, Noguchi A, Kimura H, Hashimoto N, Hayakawa J, Ogura A, Doi K. Characterization of CD4+CD8+ thymocytes observed in SCID-bg mice. Immunol Cell Biol 1997; 75:472-7. [PMID: 9429895 DOI: 10.1038/icb.1997.73] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Previously, we reported that a strain of severe combined immunodeficient (SCID) mice, namely SCID-bg, spontaneously develop CD4+CD8+ double positive (DP) thymocytes despite their scid mutation. In the present study, we intend to further characterize the DP thymocyte population in SCID-bg mice with Southern hybridization and flow cytometry. Southern hybridization analyses of sorted DP thymocytes in SCID-bg mice showed rearrangement of T cell receptor (TCR) beta and TCR gamma gene segments, although the expression of TCR beta and gamma delta TCR molecules was absent. The phenotype of the DP thymocytes in SCID-bg mice was CD44- heat-stable antigen (HSA)+CD25-, and they did not express CD69. Interestingly, the expression of thymus leukaemia (TL) antigen was observed in the DP thymocytes of SCID-bg mice but not in their CD4-CD8- double negative (DN) fraction. Fas expression was higher and bcl-2 expression was down-regulated in the DP thymocytes as compared to the DN thymocytes in SCID-bg mice, suggesting that they are not immortalized cells having escaped from apoptosis. Taken together, these results show that the phenotype of the DP thymocytes in SCID-bg mice is similar to that of the earliest phase of the DP thymocytes in normal mice, although the expression of the molecules in the pre-TCR complex is absent.
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Affiliation(s)
- S Shibata
- Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan.
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30
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Kosugi A, Noda S, Saitoh S, Narumiya S, Ogata M, Hashimoto Y, Takase K, Saito T, Hamaoka T. Subunit composition of the pre-T-cell receptor complex analysed by monoclonal antibody against the pre-T-cell receptor alpha chain. Immunology 1997; 91:618-22. [PMID: 9378503 PMCID: PMC1363884 DOI: 10.1046/j.1365-2567.1997.00294.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The pre-T-cell receptor (TCR) complex, which consists of a heterodimer of the TCR beta-chain and the pre-TCR alpha-chain, is known to regulate early thymocyte development. The pre-TCR complex contains CD3 subunits as a signal-transducing molecule, but the exact subunit composition of the fully assembled pre-TCR complex remains to be elucidated. In particular, the association of the CD3 zeta-chain with the pre-TCR is controversial. In the present study, we have generated a monoclonal antibody against the cytoplasmic portion of the pre-TCR alpha-chain, and analysed a subunit composition of the pre-TCR complex. We demonstrated that the CD3 zeta-chain is physically associated with the pre-TCR in immature T cells. Thus, the result strongly supports the previous findings that CD3 zeta contributes to signalling mediated through the pre-TCR complex.
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MESH Headings
- Animals
- Antibodies, Monoclonal/biosynthesis
- Antibodies, Monoclonal/immunology
- Electrophoresis, Polyacrylamide Gel
- Immunoblotting
- Mice
- Precipitin Tests
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Signal Transduction/immunology
- T-Lymphocyte Subsets/immunology
- Tumor Cells, Cultured
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Affiliation(s)
- A Kosugi
- School of Allied Health Sciences, Osaka University Medical School, Faculty of Medicine Osaka University, Japan
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31
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Abstract
To reach the cell surface, the T cell receptor for antigen (TCR)-CD3 complex must assemble in the endoplasmic reticulum (ER), where single subunits are retained and degraded. However, the exact location of breakdown and the mechanism and proteases involved in destruction of free subunits have remained elusive. We show that degradation of the TCR alpha chain is impaired in the presence of lactacystin and carboxybenzyl-leucyl-leucyl-leucinal, two inhibitors for proteasomal proteolysis. We identified breakdown intermediates that were either soluble, cytosolic, and devoid of N-linked glycans, or membrane-associated and partially deglycosylated by cytosolic N-glycanase. Protease protection experiments showed a cytosolic disposition of these membrane-associated intermediates. Combined, these results argue for a cytosolic degradation route of the TCR alpha chain involving dislocation from the ER, followed by cytosolic deglycosylation and proteolysis by the proteasome.
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Affiliation(s)
- J B Huppa
- Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139, USA
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32
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Abstract
Involution of the thymus accompanies aging, a process in which the organ diminishes in size and cellularity and becomes disorganized. The rate of T cell emigration from the thymus is markedly reduced with age, and phenotypic analyses have identified alterations in the relative proportions of the major thymocyte subpopulations. The present studies made use of the capacity of the thymus to regenerate following irradiation from an intrathymic radio-resistant precursor population. By analysis of the differentiation of this "wave" of thymocytes, it was determined that aging most severely affects the earliest developmental transitions. While the overall rate of differentiation does not appear to be affected in older mice, fewer thymic progenitors initiate differentiation. The reduced expansion of late pre-T cells in the middle-aged is due to the smaller pool size of these cells.
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Affiliation(s)
- M L Thoman
- Department of Immunology, Scripps Research Institute, La Jolla, California 92037, USA
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33
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Szondy Z. Methylprednisolone and 2-chloroadenosine induce DNA fragmentation at different stages of human T-lymphocyte development. Immunol Lett 1997; 58:59-65. [PMID: 9436471 DOI: 10.1016/s0165-2478(97)02713-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Both methylprednisolone (MPS) and 2-chloroadenosine (2-CA) were shown previously to induce DNA fragmentation and cell death in human thymocytes at an optimum concentration of 1 and 40 microM, respectively. Though both compounds affected the CD4+CD8+ population, 2-CA depleted primarily thymocytes expressing medium or high levels of CD3-T-cell receptor molecule, while the glucocorticoid treatment affected cells expressing a lower level of CD3-T-cell receptor. Their effect on thymocyte viability and DNA fragmentation was observed already at day 1 of culture and involved the bcl-2 negative thymocytes. Incubation of peripheral T-lymphocytes (which express bcl-2) with the same concentration of MPS did not affect the viability for up to 5 days, while 2-CA induced 100% cell death and DNA fragmentation by day 5. If T-cells were stimulated with concanavalin A in the presence of MPS or 2-CA the cell proliferation was inhibited and a decrease in cell viability with a concomittant increase in DNA fragmentation was observed. If MPS was added at 24 h or later after mitogenic stimulation, it was not able to induce apoptosis and the inhibition of proliferation was less pronounced. 2-CA, on the other hand, inhibited proliferation and induced cell death whenever it was added to the culture. The decreased sensitivity towards the apoptosis induction effects of glucocorticoids at later phases of mitogenic stimulation can not be explained by an increased bcl-2 expression, since its expression level remained constant up to 48 h after mitogenic stimulation. Our data presented in this paper suggest: (1) that T-cells may show different sensitivity towards the same apoptosis inducer signals at different stages of the T-cell development; (2) the apoptotic sensitivity towards various signals may be different at the same stage of T-cell differentiation; and (3) their apoptotic sensitivity does not always correlate with the bcl-2 expression alone.
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Affiliation(s)
- Z Szondy
- Department of Biochemistry, University Medical School of Debrecen, Hungary.
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34
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Szondy Z, Reichert U, Bernardon JM, Michel S, Tóth R, Ancian P, Ajzner E, Fesus L. Induction of apoptosis by retinoids and retinoic acid receptor gamma-selective compounds in mouse thymocytes through a novel apoptosis pathway. Mol Pharmacol 1997; 51:972-82. [PMID: 9187263 DOI: 10.1124/mol.51.6.972] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Retinoic acids are morphogenic signaling molecules that are derived from vitamin A and involved in a variety of tissue functions. Two groups of their nuclear receptors have been identified: retinoic acid receptors (RARs) and retinoic acid X receptors (RXRs). All-trans retinoic acid is the high affinity ligand for RARs, and 9-cis retinoic acid also binds to RXRs with high affinity. In cells at high concentrations, all-trans retinoic acid can be converted to 9-cis retinoic acid via unknown mechanisms. It was previously shown that retinoic acids prevents activation-induced death of thymocytes. Here, we report that both all-trans and 9-cis retinoic acid induce apoptosis of mouse thymocytes and purified CD4+CD8+ cells in ex vivo cultures, with 9-cis retinoic acid being 50 times more effective. The induction of apoptosis by retinoic acids is mediated by RARgamma because (a) the phenomenon can be reproduced only by RARgamma-selective retinoic acid analogs, (b) the cell death induced by either retinoic acids or RARgamma analogs can be inhibited by RARgamma-specific antagonists, and (c) CD4+CD8+ thymocytes express RARgamma. In vivo administration of an RARgamma analog resulted in thymus involution with the concomitant activation of the apoptosis-related endonuclease and induction of tissue transglutaminase. The RARgamma pathway of apoptosis is RNA and protein synthesis dependent, affects the CD4+CD8+ double positive thymocytes, and can be inhibited by the addition of either Ca2+ chelators or protease inhibitors. Using various RAR- and RXR-specific analogs and antagonists, it was demonstrated that stimulation of RAR alpha inhibits the RARgamma-specific death pathway (which explains the lack of apoptosis stimulatory effects of all-trans retinoic acid at physiological concentrations) and that costimulation of the RXR receptors (in the case of 9-cis retinoic acid) can neutralize this inhibitory effect. It is suggested that formation of 9-cis retinoic acid may be a critical element in regulating both the positive selection and the "default cell death pathway" of thymocytes.
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Affiliation(s)
- Z Szondy
- Department of Biochemistry, University Medical School of Debrecen, Hungary
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35
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Henning SW, Galandrini R, Hall A, Cantrell DA. The GTPase Rho has a critical regulatory role in thymus development. EMBO J 1997; 16:2397-407. [PMID: 9171353 PMCID: PMC1169840 DOI: 10.1093/emboj/16.9.2397] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The present study employs a genetic approach to explore the role of Rho GTPases in murine thymic development. Inactivation of Rho function in the thymus was achieved by thymic targeting of a transgene encoding C3 transferase from Clostridium botulinum which selectively ADP-ribosylates Rho within its effector domain and thereby abolishes its biological function. Thymi lacking functional Rho isolated from C3 transgenic mice were strikingly smaller and showed a marked (90%) decrease in cellularity compared with their normal litter mates. We also observed a similar decrease in levels of peripheral T cells in C3 transgenic mice. Analysis of the maturation status of thymocytes indicated that differentiation of progenitor cells to mature T cells can occur in the absence of Rho function, and both positive and negative selection of T cells appear to be intact. However, transgenic mice that lack Rho function in the thymus show maturational, proliferative and cell survival defects during T-cell development that severely impair the generation of normal numbers of thymocytes and mature peripheral T cells. The present study thus identifies a role for Rho-dependent signalling pathways in thymocyte development. The data show that the function of Rho GTPases is critical for the proliferative expansion of thymocytes. This defines a selective role for the GTPase Rho in early thymic development as a critical integrator of proliferation and cell survival signals.
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Affiliation(s)
- S W Henning
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, London, UK.
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36
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Anderson G, Anderson KL, Tchilian EZ, Owen JJ, Jenkinson EJ. Fibroblast dependency during early thymocyte development maps to the CD25+ CD44+ stage and involves interactions with fibroblast matrix molecules. Eur J Immunol 1997; 27:1200-6. [PMID: 9174611 DOI: 10.1002/eji.1830270522] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have investigated the role of specific components of the thymic stroma during development of CD4-8-T cell precursors by separating and reaggregating precursor subsets with individual or combinations of stromal cells. We show that while the development of CD25+ 44+ precursors is dependent upon a combination of major histocompatibility complex (MHC) class II+ thymic epithelial cells and fibroblasts, their direct descendants, CD25+ 44- precursors, develop to the CD4+ 8+ stage in the presence of MHC class II+ thymic epithelial cells alone. Thus, CD25+ 44+ precursors are the last developmental stage to be dependent upon fibroblast support. In addition, while metabolically inactive, 1-ethyl-3-(3'-dimethylaminopropyl) carbodiimide (ECDI)-treated fibroblasts retain the ability to promote T cell development, prior treatment with hyaluronidase abrogates this effect, suggesting that fibroblast-associated extracellular matrix components are the key elements involved. In support of this, we show that fibroblasts are located in cortical regions of the thymus where T cell precursors are known to reside, and that these fibroblasts are associated with an extensive extracellular matrix not found on thymic epithelial cells. Finally, antibodies to alpha 4 integrin and CD44 interfere with the efficiency with which CD4+ 8+ cells are generated from CD25+ 44+ precursors in reaggregate cultures and also reduce the binding of the latter to 3T3 fibroblasts, suggesting these molecules play a role in bringing T cell precursors into contact with fibroblast-associated extracellular matrix.
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Affiliation(s)
- G Anderson
- Department of Anatomy/Centre for Clinical Research in Immunology and Signalling, Medical School, University of Birmingham, GB.
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37
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Su DM, Wang J, Lin Q, Cooper MD, Watanabe T. Interferons alpha/beta inhibit IL-7-induced proliferation of CD4- CD8- CD3- CD44+ CD25+ thymocytes, but do not inhibit that of CD4- CD8- CD3- CD44- CD25- thymocytes. Immunology 1997; 90:543-9. [PMID: 9176107 PMCID: PMC1456697 DOI: 10.1046/j.1365-2567.1997.00205.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Type 1 interferons (IFN-alpha/beta) have recently been shown to inhibit interleukin-7 (IL-7)-induced growth and survival of early B-lineage cells. The CD3- CD4- CD8- (triple negative; TN) thymocytes from normal mice strongly proliferated upon stimulation with IL-7 in suspension, culture. Such an IL-7-induced proliferation was suppressed by the addition of IFN-alpha/beta, but a fraction of the TN thymocytes still showed proliferation. The IL-7-induced growth of TN thymocytes from acid mice, which lack the CD44- CD25- subpopulation, was completely inhibited by the addition of IFN-alpha/beta. The IL-7 induced proliferation of CD4- CD8- thymocytes from T-cell receptor (TCR) transgenic mice, the majority of which are CD3+ CD44- CD25-, was resistant to IFN-alpha/beta-mediated suppression. In fetal thymus organ cultures (FTOC), the addition of IL-7 greatly increased the population of CD4- CD8- CD44+ CD25+ thymocytes and IFN-alpha/beta inhibited this IL-7-driven expansion. In contrast, the addition of IL-7 markedly decreased the percentages of CD4- CD8- CD3- CD44- CD25- cells, and IFN-alpha/beta reversed the effect and increased the subpopulations of CD44- CD25+ and CD44- CD25-. Finally, IFN-beta mRNA was found to be expressed in the thymus. The data suggest that type I interferons inhibit IL-7-driven proliferation of TN thymocytes, but do not block the normal differentiation process.
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Affiliation(s)
- D M Su
- Department of Molecular Immunology, Kyushu University, Fukuoka, Japan
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38
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Shibata S, Asano T, Ogura A, Hashimoto N, Hayakawa J, Naiki M, Doi K. TCR beta-independent development of CD4+ CD8+ thymocytes observed in a strain of scid mice. Immunol Cell Biol 1997; 75:154-60. [PMID: 9107568 DOI: 10.1038/icb.1997.21] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Mice homozygous for severe combined immunodeficiency (scid) mutation usually halt their thymocyte development at the CD4-CD8- double negative (DN) stage due to their inability of TCR gene rearrangement. In this study, we report that SCID-bg mice, which were originally generated by mating CB-17-scid mice with KSN-bg mice, spontaneously develop dominant CD4+ CD8+ double positive (DP) thymocytes. Their thymi were mainly composed of DN, CD4-CD8+ and DP cells, and the majority of them did not present CD3. Similarly, they lacked TCR beta expression both on cell surface and in cytoplasm, which suggests that the thymocyte development to the DP stage observed in SCID-bg mice, was independent of CD3 and TCR beta expression. In spite of significant DP thymocytes in SCID-bg mice, the histology of their thymi was not so different from those of CB-17-scid mice. Analysis of bone marrow cells in SCID-bg mice showed that the development of B lineage cells was not altered when compared with CB-17-scid mice. These findings point out the fact that thymocytes in SCID-bg mice have a peculiar characteristic compared to CB-17-scid mice, and provide evidence of TCR beta-independent development of thymocytes to the DP stage.
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Affiliation(s)
- S Shibata
- Department of Veterinary Science, National Institute of Health, Tokyo, Japan
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39
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Jolly CJ, O'Neill HC. Specific transcription of the unrearranged TCR V beta 8.2 gene in lymphoid tissues occurs independently of V(D)J rearrangement. Immunol Cell Biol 1997; 75:13-20. [PMID: 9046429 DOI: 10.1038/icb.1997.3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A truncated T cell receptor (TCR) V beta 8.2 polypeptide expressed on the surface of a precursor lymphoid cell line and on a subset of mesenteric lymph node cells has previously been shown to be encoded by transcripts from unrearranged V beta 8 genes. Germline V beta 8 transcription has now been demonstrated in multiple lymphoid and non-lymphoid tissues in mice of varying ages and in cultured cell lines by reverse transcription-polymerase chain reaction (RT-PCR). Significant levels of V beta 8 germline transcription were found in thymus, spleen, liver and bone marrow and in all lymphoid cell lines studied. Germline V beta 8 transcription in the liver dropped as mice aged, and increased in the bone marrow. Germline V beta 8 transcription was also detectable in thymus, spleen, liver and bone marrow of RAG-1-/- mice. This indicated that it is not dependent upon the presence of mature lymphoid cells, nor necessarily related to V(D)J rearrangement events. Semi-quantitative polymerase chain reaction (PCR) and hybridization with oligonucleotides specific for V beta 8.1, 8.2 and 8.3 showed that the V beta 8.2 gene produced at least 90% of all the germline V beta 8 transcripts in all of the tissues examined. The significance of these results in lymphoid cell development and for models of the regulation of V(D)J rearrangement are discussed.
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MESH Headings
- Alternative Splicing/genetics
- Alternative Splicing/physiology
- Animals
- Antibody Diversity/genetics
- Antibody Diversity/physiology
- Cell Line
- Cloning, Molecular
- Exons/genetics
- Gene Expression
- Gene Rearrangement, beta-Chain T-Cell Antigen Receptor/genetics
- Genes, Immunoglobulin/genetics
- Genes, Immunoglobulin/physiology
- Germ Cells/physiology
- Hematopoietic Stem Cells/metabolism
- Humans
- In Vitro Techniques
- Lymphoid Tissue/cytology
- Lymphoid Tissue/metabolism
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Inbred DBA
- Polymerase Chain Reaction
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Transcription, Genetic
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Affiliation(s)
- C J Jolly
- Division of Biochemistry and Molecular Biology, School of Life Sciences, Australian National University, Canberra, Australia
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40
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Melchers F. Control of the sizes and contents of precursor B cell repertoires in bone marrow. CIBA FOUNDATION SYMPOSIUM 1997; 204:172-82; discussion 182-6. [PMID: 9107420 DOI: 10.1002/9780470515280.ch12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Ordered rearrangements of immunoglobulin (Ig) gene loci, first as DH to JH, then as VH to DHJH, and finally as VL to JL segment-specific recombinations occur 'in-frame' and 'out-of-frame'. 'In-frame' rearrangements lead to the expression of truncated DHJH-microC proteins and to microH chains. These H chain proteins have two major effects on precursor B cells. They suppress (as DJC mu proteins) or enhance (as full microH chain) the proliferation of precursor cells at the point where these precursors express these proteins. At the same time, they signal allelic exclusion of the microH chain alleles, so that VH to DHJH rearrangement at the second allele is suppressed. Regulation of precursor B cell proliferation and H chain allelic exclusion is mediated by a pre-B cell receptor that is composed of the microH chains and a surrogate L chain. This surrogate L chain is made up of two proteins encoded by the Vpre-B and lambda 5 genes that are expressed only at the early precursor cell stages just before and when H chain genes are first expressed. They are not found in later B cell development, when L chains are expressed, nor in any other cell of the body tested so far. The physiological roles of surrogate L chain and of the pre-B receptor have been clarified by generating mutant mice in which the lambda 5 gene has been inactivated by targeted disruption. Molecular mechanisms and cellular developments, by which the pre-B receptor controls proliferation and allelic exclusion, are discussed.
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Affiliation(s)
- F Melchers
- Basel Institute for Immunology, Switzerland
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41
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Falk I, Biro J, Kohler H, Eichmann K. Proliferation kinetics associated with T cell receptor-beta chain selection of fetal murine thymocytes. J Exp Med 1996; 184:2327-39. [PMID: 8976187 PMCID: PMC2196377 DOI: 10.1084/jem.184.6.2327] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
After productive rearrangement of a TCR beta chain gene, CD4-8- double negative (DN) thymocytes express TCR beta polypeptide chains on the cell surface together with pre-T alpha and the CD3 complex forming the pre-TCR. Signals transmitted through the pre-TCR select TCR beta + DN thymocytes for further maturation to the CD4+8+ double positive stage, whereas DN cells that fail to generate a productive TCR beta gene rearrangement do not continue in development. This process is termed TCR beta chain selection. Although it is likely that differences between proliferation dynamics of TCR beta + and TCR beta-cells may play a role, the exact mechanisms of TCR beta chain selection have not been elucidated. We therefore studied the proliferation dynamics of TCR beta + and TCR beta-thymocytes during fetal development, i.e., when TCR beta chain selection takes place for the first time. We analyzed in situ accumulation of TCR beta + thymocytes by confocal microscopy, and determined cell cycle and division parameters of TCR beta + and TCR beta-populations by flow cytometry. About 600 TCR beta + cells/thymic lobe are generated by independent induction events between days of gestation (dg) 13.5, and 15.5. As of dg 14.5, most TCR beta + cells have entered S/G2 phase of cell cycle, followed by seven to eight rapid cell divisions in fetal thymic organ culture, suggesting a corresponding burst of nine cell divisions within 4 d in vivo. By dg 18.5, the division rate of TCR beta + cells has slowed down to less than 1/d. About three quarters of TCR beta-cells divide at a slow rate of 1/d on dg 14.5, the proportion of nondividing cells increasing to 50% within the following four d. From dg 16.5 onwards, TCR beta-cells, but not TCR beta + cells, contain a significant proportion of apoptotic cells. The results suggest that failure to become selected results in shutdown of proliferation and eventual programmed cell death of fetal TCR beta-cells. Positive selection of fetal TCR beta + cells is achieved by an increased rate of cell divisions lasting for approximately 4 d.
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Affiliation(s)
- I Falk
- Max-Planck-Institut für Immunbiologie, Freiburg, Germany
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42
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Swat W, Shinkai Y, Cheng HL, Davidson L, Alt FW. Activated Ras signals differentiation and expansion of CD4+8+ thymocytes. Proc Natl Acad Sci U S A 1996; 93:4683-7. [PMID: 8643464 PMCID: PMC39339 DOI: 10.1073/pnas.93.10.4683] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We describe a novel approach to assay the ability of particular gene products to signal transitions in lymphocyte differentiation in vivo. The method involves transfection of test expression constructs into RAG-1-deficient embryonic stem cells, which are subsequently assayed by the RAG-2-deficient blastocyst complementation approach. We have used this method to demonstrate that expression of activated Ras in CD4-8- (double negative, DN) prothymocytes in vivo induces their differentiation into small CD4+8+ (double positive, DP) cortical thymocytes with accompanying expansion to normal thymocyte numbers. However, activated Ras expression in DP cells does not cause proliferation or maturation to CD4+8- or CD4-8+ (single positive) thymocytes. Therefore, signaling through Ras is sufficient for promoting differentiation of DN to DP cells, but further differentiation requires the activity of additional signaling pathways.
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Affiliation(s)
- W Swat
- Howard Hughes Medical Institute, The Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
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43
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Tokoro Y, Tsuda S, Tanaka S, Nakauchi H, Takahama Y. CD3-induced apoptosis of CD4+CD8+ thymocytes in the absence of clonotypic T cell antigen receptor. Eur J Immunol 1996; 26:1012-7. [PMID: 8647161 DOI: 10.1002/eji.1830260509] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Clonal selection of T cells mediated through the T cell antigen receptor (TCR) mostly occurs at the CD4+CD8+ double positive thymocyte stage. Immature CD4+CD8+ thymocytes expressing self-reactive TCR are induced to die upon clonotypic engagement of TCR by self antigens. CD3 engagement by antibody of the surface TCR-CD3 complex is known to induce apoptosis of CD4+CD8+ thymocytes, a process that is generally thought to represent antigen-induced negative selection in the thymus. The present study shows that the CD3-induced apoptosis of CD4+CD8+ thymocytes can occur even in TCR alpha- mutant mice which do not express the TCR alpha beta/CD3 antigen receptor. Anti-CD3 antibody induces death of CD4+CD8+ thymocytes in TCR alpha- mice either in cell cultures or upon administration in vivo. Interestingly, most surface CD3 chains expressed on CD4+CD8+ thymocytes from TCR alpha- mice are not associated with clonotypic TCR chains, including TCR beta. Thus, apoptosis of CD4+CD8+ thymocytes appear to be induced through the CD3 complex even in the absence of clonotypic antigen receptor chains. These results shed light on previously unknown functions of the clonotype-independent CD3 complex expressed on CD4+CD8+ thymocytes, and suggest its function as an apoptotic receptor inducing elimination of developing thymocytes.
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Affiliation(s)
- Y Tokoro
- Department of Immunology, University of Tsukuba, Japan
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44
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Abstract
Interactions between stromal cells and thymocytes play a crucial role in T cell development. The thymic stroma is complex and consists of epithelial cells derived from the pharyngeal region during development, together with macrophages and dendritic cells of bone marrow origin. In addition, fibroblasts and matrix molecules permeate the whole framework. It is now apparent that these individual stromal components play specialized roles at different stages of T cell differentiation. Thus, at the early CD4-8- stage of development, T cell precursors require fibroblast as well as epithelial cell interactions. Later, at the CD4+8+ stage, as well as providing low avidity TCR/MHC-peptide interactions, thymic epithelial cells have been shown to possess unique properties essential for positive selection. Dendritic cells, on the other hand, are probably efficient mediators of negative selection, but they may not be solely responsible for this activity. Alongside the functional roles of stromal cells, considerable progress is being made in unraveling the nature of the signaling pathways involved in T cell development. Identification of the pre-T cell receptor (pre-TCR) and associated signaling molecules marks an important advance in understanding the mechanisms that control gene rearrangement and allelic exclusion. In addition, a better understanding of the signaling pathways that lead to positive selection on the one hand and negative selection on the other is beginning to emerge. Many issues remain unresolved, and some are discussed in this review. What, for example, is the nature of the chemotactic factor(s) that attract stem cells to the thymus? What is the molecular basis of the essential interactions between early thymocytes and fibroblasts, and early thymocytes and epithelial cells? What is special about cortical epithelial cells in supporting positive selection? These and other issues are ripe for analysis and can now be approached using a combination of modern molecular and cellular techniques.
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Affiliation(s)
- G Anderson
- Department of Anatomy, Medical School, University of Birmingham, United Kingdom
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45
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Abstract
T lymphocytes differentiate from hematopoietic stem cells that settle in the microenvironment of the thymus. The earliest stages of mouse alpha/beta T-cell differentiation occurring before surface expression of the TCR include three important events: proliferation, commitment to the T lineage, and rearrangement and expression of the TCR loci. Recent evidence suggests that the survival as well as differentiation of early thymocytes depends critically on molecular signals such as those generated by the recently described pre-TCR complex.
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46
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Bogue MA, Zhu C, Aguilar-Cordova E, Donehower LA, Roth DB. p53 is required for both radiation-induced differentiation and rescue of V(D)J rearrangement in scid mouse thymocytes. Genes Dev 1996; 10:553-65. [PMID: 8598286 DOI: 10.1101/gad.10.5.553] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The murine scid mutation affects both V(D)J recombination and DNA repair. This mutation has been mapped to the gene encoding the catalytic subunit of the DNA-dependent protein kinase (DNA-PK), which is activated by DNA damage in normal cells. In scid mice, antigen receptor gene rearrangements are initiated normally, but impaired joining of coding ends prevents assembly of functional receptor genes, resulting in arrest of B- and T-cell development. Others have shown that exposure of scid mice to genotoxic agents such as gamma-irradiation rescues rearrangement at the T-cell receptor (TCR) beta locus and promotes thymocyte development. Here we demonstrate that irradiation rescues rearrangements at multiple TCR loci, suggesting a general effect on the recombination mechanism. Furthermore, our data show that p53 is required for irradiation-mediated rescue of both thymocyte development and V(D)J recombination. We also find that thymocyte proliferation and differentiation in the absence of DNA damage do not require p53 and are not sufficient to rescue V(D)J recombination. These results suggest that exposure to ionizing radiation facilitates a partial bypass of the scid defect, perhaps by inducing p53-dependent DNA damage response pathways.
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Affiliation(s)
- M A Bogue
- Department of Microbiology and Immunology, Baylor College of Medicine, Houston, Texas 77030, USA
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47
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Rincon M, Flavell RA. Regulation of AP-1 and NFAT transcription factors during thymic selection of T cells. Mol Cell Biol 1996; 16:1074-84. [PMID: 8622652 PMCID: PMC231090 DOI: 10.1128/mcb.16.3.1074] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The ability of thymocytes to express cytokine genes changes during the different stages of thymic development. Although CD4- CD8- thymocytes are able to produce a wide spectrum of cytokines in response to a T-cell receptor (TcR)-independent stimulus, as they approach the double-positive (DP) CD4+ CD8+ stage, they lose the ability to produce cytokine. After the DP stage, thymocytes become single-positive CD4+ or CD8+ thymocytes which reacquire the ability to secrete cytokines. In an attempt to understand the molecular basis of this specific regulatin, we use AP-1-luciferase and newly generated NFAT-luciferase transgenic mice to analyze the transcriptional and DNA-binding activities of these two transcription factors that are involved in the regulation of cytokine gene expression. Here, we show that both AP-1 and NFAT transcriptional activities are not inducible in the majority of DP cells but that during the differentiation of DP cells to the mature single-positive stage, thymocytes regain this inducibility. Subpopulation analysis demonstrates that this inducibility is reacquired at the DP stage before the down-modulation of one of the coreceptors. Indeed AP-1 inducibility, just like the ability to express the interleukin-2 gene, is reacquired during the differentiation of DP TcRlow CD69low heat-stable antigen (HSA)high thymocytes to DP TcRhigh CD69high HSAhigh cells, which is considered to be the consequence of the first signal that initiates positive selection. We therefore propose that the inability of DP thymocytes to induce AP-1 and NFAT activities is one of the causes for the lack of cytokine gene expression at this stage and that this inducibility is reacquired at the latest stage of DP differentiation as a consequence of positive selection. This could be a mechanism to prevent the activation of DP thymocytes before selection has taken place.
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Affiliation(s)
- M Rincon
- Section of Immunobiology, Yale University, School of Medicine, New Haven, Connecticut 06510, USA
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48
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van Oers NS, Killeen N, Weiss A. Lck regulates the tyrosine phosphorylation of the T cell receptor subunits and ZAP-70 in murine thymocytes. J Exp Med 1996; 183:1053-62. [PMID: 8642247 PMCID: PMC2192313 DOI: 10.1084/jem.183.3.1053] [Citation(s) in RCA: 261] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The Src-family and Syk/ZAP-70 family of protein tyrosine kinases (PTK) are required for T cell receptor (TCR) functions. We provide evidence that the Src-family PTK Lck is responsible for regulating the constitutive tyrosine phosphorylation of the TCR zeta subunit in murine thymocytes. Moreover, ligation of the TCR expressed on thymocytes from Lck-deficient mice largely failed to induce the phosphorylation of TCR-zeta, CD3 epsilon, or ZAP-70. In contrast, we find that the TCR-zeta subunit is weakly constitutively tyrosine phosphorylated in peripheral T cells isolated from Lck-null mice. These data suggest that Lck has a functional role in regulation of TCR signal transduction in thymocytes. In peripheral T cells, other Src-family PTKs such as Fyn may partially compensate for the absence of Lck.
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MESH Headings
- Animals
- Cells, Cultured
- Flow Cytometry
- Immunoblotting
- Lymphocyte Specific Protein Tyrosine Kinase p56(lck)
- Membrane Proteins/isolation & purification
- Membrane Proteins/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Phosphorylation
- Phosphotyrosine/analysis
- Phosphotyrosine/metabolism
- Receptor-CD3 Complex, Antigen, T-Cell/immunology
- Receptor-CD3 Complex, Antigen, T-Cell/metabolism
- Receptors, Antigen, T-Cell/isolation & purification
- Receptors, Antigen, T-Cell/metabolism
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- Thymus Gland/immunology
- Tyrosine/metabolism
- src-Family Kinases/deficiency
- src-Family Kinases/genetics
- src-Family Kinases/metabolism
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Affiliation(s)
- N S van Oers
- Department of Medicine, University of California, San Francisco, 94143,USA
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49
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Affiliation(s)
- S Desiderio
- Department of Molecular Biology and Genetics, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21210, USA
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50
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Affiliation(s)
- J Chen
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA
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