1
|
Salz A, Gurniak C, Jönsson F, Witke W. Cofilin1-driven actin dynamics controls migration of thymocytes and is essential for positive selection in the thymus. J Cell Sci 2020; 133:jcs238048. [PMID: 31974112 DOI: 10.1242/jcs.238048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 01/14/2020] [Indexed: 11/20/2022] Open
Abstract
Actin dynamics is essential for T-cell development. We show here that cofilin1 is the key molecule for controlling actin filament turnover in this process. Mice with specific depletion of cofilin1 in thymocytes showed increased steady-state levels of actin filaments, and associated alterations in the pattern of thymocyte migration and adhesion. Our data suggest that cofilin1 is controlling oscillatory F-actin changes, a parameter that influences the migration pattern in a 3-D environment. In a collagen matrix, cofilin1 controls the speed and resting intervals of migrating thymocytes. Cofilin1 was not involved in thymocyte proliferation, cell survival, apoptosis or surface receptor trafficking. However, in cofilin1 mutant mice, impaired adhesion and migration resulted in a specific block of thymocyte differentiation from CD4/CD8 double-positive thymocytes towards CD4 and CD8 single-positive cells. Our data suggest that tuning of the dwelling time of thymocytes in the thymic niches is tightly controlled by cofilin1 and essential for positive selection during T-cell differentiation. We describe a novel role of cofilin1 in the physiological context of migration-dependent cell differentiation.
Collapse
Affiliation(s)
- Andree Salz
- Institute of Genetics, University of Bonn, Karlrobert-Kreiten Strasse 13, 53115 Bonn, Germany
| | - Christine Gurniak
- Institute of Genetics, University of Bonn, Karlrobert-Kreiten Strasse 13, 53115 Bonn, Germany
| | - Friederike Jönsson
- Unit of Antibodies in Therapy and Pathology, Institut Pasteur, UMR 1222 INSERM, 75015 Paris, France
| | - Walter Witke
- Institute of Genetics, University of Bonn, Karlrobert-Kreiten Strasse 13, 53115 Bonn, Germany
| |
Collapse
|
2
|
Yang JQ, Kalim KW, Li Y, Zheng Y, Guo F. Ablation of RhoA impairs Th17 cell differentiation and alleviates house dust mite-triggered allergic airway inflammation. J Leukoc Biol 2019; 106:1139-1151. [PMID: 31260596 DOI: 10.1002/jlb.3a0119-025rrr] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Revised: 06/17/2019] [Accepted: 06/18/2019] [Indexed: 01/10/2023] Open
Abstract
Asthma is a heterogeneous chronic airway inflammation in which Th2 and Th17 cells are key players in its pathogenesis. We have reported that RhoA of Rho GTPases orchestrated glycolysis for Th2 cell differentiation and allergic airway inflammation by the use of a conditional RhoA-deficient mouse line. However, the role of RhoA in Th17 cells remains to be elucidated. In this study, we investigated the effects of RhoA deficiency on Th17 cells in the context of ex vivo cell culture systems and an in vivo house dust mites (HDM)-induced allergic airway inflammation. We found that RhoA deficiency inhibited Th17 differentiation and effector cytokine secretion, which was associated with the downregulations of Stat3 and Rorγt, key Th17 transcription factors. Furthermore, loss of RhoA markedly suppressed Th17 and neutrophil-involved airway inflammation induced by HDM in mice. The infiltrating inflammatory cells in the lungs and bronchoalveolar lavage (BAL) fluids were dramatically reduced in conditional RhoA-deficient mice. Th17 as well as Th2 effector cytokines were suppressed in the airways at both protein and mRNA levels. Interestingly, Y16, a specific RhoA inhibitor, was able to recapitulate the most phenotypes of RhoA genetic deletion in Th17 differentiation and allergic airway inflammation. Our data demonstrate that RhoA is a key regulator of Th17 cell differentiation and function. RhoA might serve as a potential novel therapeutic target for asthma and other inflammatory disorders.
Collapse
Affiliation(s)
- Jun-Qi Yang
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.,Key Laboratory of National Health Commission on Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasitic and Vector Control, Jiangsu Institute of Parasitic Diseases and Public Health Research Center, Jiangnan University, Wuxi, Jiangsu, China
| | - Khalid W Kalim
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Yuan Li
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Yi Zheng
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Fukun Guo
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| |
Collapse
|
3
|
Abstract
PURPOSE OF REVIEW Once an obscure disease, recent studies have transformed our understanding of angioimmunoblastic T-cell lymphoma (AITL). In this review, we summarize new major advances in the genetics and biology of AITL. RECENT FINDINGS Genome wide sequencing studies have dissected the repertoire of the genetic alterations driving AITL uncovering a highly recurrent Gly17Val somatic mutation in the small GTPase RHOA and major role for mutations in epigenetic regulators, such as TET2, DNMT3A and IDH2, and signaling factors (e.g., FYN and CD28). These findings support a multistep model of follicular T helper cell transformation in AITL and pinpoint novel candidates for the development of targeted therapies in this disease. SUMMARY AITL originates from follicular T helper cells and is characterized by the presence of RHOA G17V mutation together with genetic alterations in TET2, DNMT3A, and IDH2. Research efforts now focus on the elucidation of the specific roles and interplay of these genetic alterations in the pathogenesis of AITL.
Collapse
|
4
|
Abstract
Effective immune responses require the precise regulation of dynamic interactions between hematopoietic and non-hematopoietic cells. The Rho subfamily of GTPases, which includes RhoA, is rapidly activated downstream of a diverse array of biochemical and biomechanical signals, and is emerging as an important mediator of this cross-talk. Key downstream effectors of RhoA are the Rho kinases, or ROCKs. The ROCKs are two serine-threonine kinases that can act as global coordinators of a tissue’s response to stress and injury because of their ability to regulate a wide range of biological processes. Although the RhoA-ROCK pathway has been extensively investigated in the non-hematopoietic compartment, its role in the immune system is just now becoming appreciated. In this commentary, we provide a brief overview of recent findings that highlight the contribution of this pathway to lymphocyte development and activation, and the impact that dysregulation in the activation of RhoA and/or the ROCKs may exert on a growing list of autoimmune and lymphoproliferative disorders.
Collapse
Affiliation(s)
- Edd Ricker
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, New York, 10021, USA; Graduate Program in Immunology and Microbial Pathogenesis, Weill Cornell Graduate School of Medical Sciences, New York, New York, 10065, USA
| | - Luvana Chowdhury
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, New York, 10021, USA
| | - Woelsung Yi
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, New York, 10021, USA; David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, New York, 10021, USA
| | - Alessandra B Pernis
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, New York, 10021, USA; Graduate Program in Immunology and Microbial Pathogenesis, Weill Cornell Graduate School of Medical Sciences, New York, New York, 10065, USA; David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, New York, 10021, USA; Department of Medicine, Weill Cornell Medical College, New York, New York, 10021, USA
| |
Collapse
|
5
|
Tamehiro N, Oda H, Shirai M, Suzuki H. Overexpression of RhoH Permits to Bypass the Pre-TCR Checkpoint. PLoS One 2015; 10:e0131047. [PMID: 26114424 PMCID: PMC4482576 DOI: 10.1371/journal.pone.0131047] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 05/28/2015] [Indexed: 11/19/2022] Open
Abstract
RhoH, an atypical small Rho-family GTPase, critically regulates thymocyte differentiation through the coordinated interaction with Lck and Zap70. Therefore, RhoH deficiency causes defective T cell development, leading to a paucity of mature T cells. Since there has been no gain-of-function study on RhoH before, we decided to take a transgenic approach to assess how the overexpression of RhoH affects the development of T cells. Although RhoH transgenic (RhoHtg) mice expressed three times more RhoH protein than wild-type mice, β-selection, positive, and negative selection in the thymus from RhoHtg mice were unaltered. However, transgenic introduction of RhoH into Rag2 deficient mice resulted in the generation of CD4+CD8+ (DP) thymocytes, indicating that overexpression of RhoH could bypass β-selection without TCRβ gene rearrangement. This was confirmed by the in vitro development of DP cells from Rag2-/-RhoHtg DN3 cells on TSt-4/Dll-1 stroma in an Lck dependent manner. Collectively, our results indicate that an excess amount of RhoH is able to initiate pre-TCR signaling in the absence of pre-TCR complexes.
Collapse
Affiliation(s)
- Norimasa Tamehiro
- Department of Immunology and Pathology, Research Institute, National Center for Global Health and Medicine, Chiba, Japan
| | - Hiroyo Oda
- Department of Immunology and Pathology, Research Institute, National Center for Global Health and Medicine, Chiba, Japan
| | - Mutsunori Shirai
- Department of Microbiology, Yamaguchi University School of Medicine, Ube, Japan
| | - Harumi Suzuki
- Department of Immunology and Pathology, Research Institute, National Center for Global Health and Medicine, Chiba, Japan
- * E-mail:
| |
Collapse
|
6
|
Ohsugi T. A transgenic mouse model of human T cell leukemia virus type 1-associated diseases. Front Microbiol 2013; 4:49. [PMID: 23483782 PMCID: PMC3592262 DOI: 10.3389/fmicb.2013.00049] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 02/21/2013] [Indexed: 01/10/2023] Open
Abstract
Human T cell leukemia virus type 1 (HTLV-1) is the etiological agent of adult T cell leukemia/lymphoma (ATLL) and several inflammatory diseases. Tax, the protein encoded by HTLV-1, may be responsible for the development of the diseases caused by this virus. To investigate the pathogenic role of Tax, several transgenic mouse strains expressing Tax have been developed in recent years. These mice develop various tumors including large granular lymphocytic leukemia, as well as inflammatory diseases such as arthritis. These results suggest that Tax expression alone is sufficient to cause both malignant neoplastic diseases and inflammatory diseases. However, until recently, there were no tax transgenic mice that develop T cell leukemia and lymphoma resembling ATLL. The first successful induction of leukemia in T cells was pre-T cell leukemia generated in transgenic mice in which a mouse lymphocyte-specific protein tyrosine kinase p56lck (lck)-proximal promoter was used to express the tax gene in immature T cells. Subsequently, transgenic mice were established in which the lck-distal promoter was used to express Tax in mature T cells; these mice developed mature T cell leukemia and lymphoma that more closely resembled ATLL than did earlier mouse models.
Collapse
Affiliation(s)
- Takeo Ohsugi
- Division of Microbiology and Genetics, Institute of Resource Development and Analysis, Kumamoto University Kumamoto, Japan
| |
Collapse
|
7
|
Banerjee H, Das A, Srivastava S, Mattoo HR, Thyagarajan K, Khalsa JK, Tanwar S, Das DS, Majumdar SS, George A, Bal V, Durdik JM, Rath S. A role for apoptosis-inducing factor in T cell development. J Exp Med 2012; 209:1641-53. [PMID: 22869892 PMCID: PMC3428951 DOI: 10.1084/jem.20110306] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 07/20/2012] [Indexed: 12/14/2022] Open
Abstract
Apoptosis-inducing factor (Aif) is a mitochondrial flavoprotein that regulates cell metabolism and survival in many tissues. We report that aif-hypomorphic harlequin (Hq) mice show thymic hypocellularity and a cell-autonomous thymocyte developmental block associated with apoptosis at the β-selection stage, independent of T cell receptor β recombination. No abnormalities are observed in the B cell lineage. Transgenes encoding wild-type or DNA-binding-deficient mutant Aif rectify the thymic defect, but a transgene encoding oxidoreductase activity-deficient mutant Aif does not. The Hq thymic block is reversed in vivo by antioxidant treatment, and Hq T but not B lineage cells show enhanced oxidative stress. Thus, Aif, a ubiquitous protein, serves a lineage-specific nonredundant antiapoptotic role in the T cell lineage by regulating reactive oxygen species during thymic β-selection.
Collapse
Affiliation(s)
| | - Abhishek Das
- National Institute of Immunology, New Delhi 110067, India
| | | | | | | | | | - Shalini Tanwar
- National Institute of Immunology, New Delhi 110067, India
| | | | | | - Anna George
- National Institute of Immunology, New Delhi 110067, India
| | - Vineeta Bal
- National Institute of Immunology, New Delhi 110067, India
| | - Jeannine M. Durdik
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701
| | - Satyajit Rath
- National Institute of Immunology, New Delhi 110067, India
| |
Collapse
|
8
|
Kumar A, Kremer KN, Dominguez D, Tadi M, Hedin KE. Gα13 and Rho mediate endosomal trafficking of CXCR4 into Rab11+ vesicles upon stromal cell-derived factor-1 stimulation. THE JOURNAL OF IMMUNOLOGY 2010; 186:951-8. [PMID: 21148034 DOI: 10.4049/jimmunol.1002019] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CXCR4, like other G protein-coupled receptors, signals via heterotrimeric guanine nucleotide-binding proteins (G proteins) to regulate gene transcription, migration, development, growth, and transformation. We describe a formerly uncharacterized function of a G protein: a role in receptor trafficking. We previously showed that CXCR4 and the TCR physically associate and form a heterodimer upon stromal cell-derived factor-1 or CXCL12 (SDF-1) stimulation in human T cells to prolong ERK activation and, thereby, lead to gene upregulation and cytokine secretion. The CXCR4-TCR heterodimers occur on the cell surface and in an intracellular compartment in response to SDF-1. Neither the intracellular compartment to which the CXCR4-TCR heterodimers localize nor the mechanism for localization has been elucidated. In this article, we characterize molecular mechanisms required for postendocytic trafficking of CXCR4. Upon SDF-1 stimulation, CXCR4 localizes to Rab11(+) vesicles, a recycling compartment near the microtubule organizing center and Golgi apparatus. This trafficking requires the CXCR4 C-terminal tail domain but not the CXCR4 ubiquitination sites. The TCR also constitutively localizes to this Rab11(+) compartment. Trafficking of CXCR4 into the Rab11(+), TCR-containing endosomes requires actin polymerization. Furthermore, inhibiting Rho activation or depleting Gα13 prevented trafficking of CXCR4 into the Rab11(+) endosomes without hindering the ability of CXCR4 to endocytose. These results indicated that, upon SDF-1 treatment, Gα13 and Rho mediate the actin polymerization necessary for trafficking CXCR4 into the Rab11(+), recycling endosomal compartment, which also contains constitutively recycling TCR and, thus, CXCR4-TCR heterodimers. To our knowledge, this is the first report of Gα13 as a mediator of receptor trafficking.
Collapse
Affiliation(s)
- Ashok Kumar
- Department of Immunology, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | | | | | | | | |
Collapse
|
9
|
Finlay DK, Sinclair LV, Feijoo C, Waugh CM, Hagenbeek TJ, Spits H, Cantrell DA. Phosphoinositide-dependent kinase 1 controls migration and malignant transformation but not cell growth and proliferation in PTEN-null lymphocytes. ACTA ACUST UNITED AC 2009; 206:2441-54. [PMID: 19808258 PMCID: PMC2768858 DOI: 10.1084/jem.20090219] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In normal T cell progenitors, phosphoinositide-dependent kinase l (PDK1)–mediated phosphorylation and activation of protein kinase B (PKB) is essential for the phosphorylation and inactivation of Foxo family transcription factors, and also controls T cell growth and proliferation. The current study has characterized the role of PDK1 in the pathology caused by deletion of the tumor suppressor phosphatase and tensin homologue deleted on chromosome 10 (PTEN). PDK1 is shown to be essential for lymphomagenesis caused by deletion of PTEN in T cell progenitors. However, PTEN deletion bypasses the normal PDK1-controlled signaling pathways that determine thymocyte growth and proliferation. PDK1 does have important functions in PTEN-null thymocytes, notably to control the PKB–Foxo signaling axis and to direct the repertoire of adhesion and chemokine receptors expressed by PTEN-null T cells. The results thus provide two novel insights concerning pathological signaling caused by PTEN loss in lymphocytes. First, PTEN deletion bypasses the normal PDK1-controlled metabolic checkpoints that determine cell growth and proliferation. Second, PDK1 determines the cohort of chemokine and adhesion receptors expressed by PTEN-null cells, thereby controlling their migratory capacity.
Collapse
Affiliation(s)
- David K Finlay
- Division of Immunology and Cell Biology, University of Dundee, Dundee DD15EH, Scotland, UK
| | | | | | | | | | | | | |
Collapse
|
10
|
Xu M, Sharma A, Hossain MZ, Wiest DL, Sen JM. Sustained expression of pre-TCR induced beta-catenin in post-beta-selection thymocytes blocks T cell development. THE JOURNAL OF IMMUNOLOGY 2009; 182:759-65. [PMID: 19124718 DOI: 10.4049/jimmunol.182.2.759] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pre-TCR and IL-7R signals regulate beta-selection of thymocytes and then must be down-regulated for further development. However, the molecular events that control down-regulation remain unknown. We and others have previously shown that beta-catenin in cooperation with TCF regulates beta-selection. In this paper, we demonstrate that beta-catenin expression is stringently regulated by intrathymic signals, it is expressed at the highest levels in the pre-TCR signaled thymocytes, and is down-regulated in post-beta-selection thymocytes. Pre-TCR-induced beta-catenin regulates initial stages of pre-TCR signaling including expression of early growth response (Egr) genes but must be down-regulated to express RORgammat, which is essential for maturation to the CD4+CD8+ double positive (DP) stage. Sustained expression of beta-catenin results in the generation of IL-7R-, Egr-, and TGFbeta-expressing pre-DP thymocytes that are blocked in development. These data are consistent with a model in which post-beta-selection, pre-TCR-induced beta-catenin expression must return to background levels for efficient transition to the DP stage.
Collapse
Affiliation(s)
- Mai Xu
- Lymphocyte Development Unit, Laboratory of Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | | | | | | | | |
Collapse
|
11
|
Xu M, Sharma A, Wiest DL, Sen JM. Pre-TCR-induced beta-catenin facilitates traversal through beta-selection. THE JOURNAL OF IMMUNOLOGY 2009; 182:751-8. [PMID: 19124717 DOI: 10.4049/jimmunol.182.2.751] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pre-TCR induced signals regulate development of the alphabeta TCR lineage cells at the beta-selection checkpoint. We have previously shown that conditional deletion of beta-catenin, a central mediator of Wnt-beta-catenin-T cell factor signaling pathway, impairs traversal through the beta-selection checkpoint. We now provide a molecular basis for the impairment. We demonstrate that pre-TCR signals specifically stabilize beta-catenin in CD4-CD8- double negative thymocytes during beta-selection. Pre-TCR induced Erk activity was required to stabilize beta-catenin. Enforced expression of stabilized beta-catenin was sufficient to mediate aspects of beta-selection including sustained expression of early growth response (Egr) genes. Consistently, deletion of beta-catenin reduced induction of Egr gene expression by the pre-TCR signal and blocked efficient beta-selection. Thus, we demonstrate that pre-TCR induced beta-catenin sustains expression of Egr genes that facilitate traversal through the beta-selection checkpoint.
Collapse
Affiliation(s)
- Mai Xu
- Lymphocyte Development Unit, Laboratory of Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | | | | | | |
Collapse
|
12
|
Mullin M, Lightfoot K, Clarke R, Miller M, Lahesmaa R, Cantrell D. The RhoA transcriptional program in pre-T cells. FEBS Lett 2007; 581:4309-17. [PMID: 17716670 PMCID: PMC1964784 DOI: 10.1016/j.febslet.2007.07.077] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Revised: 07/27/2007] [Accepted: 07/30/2007] [Indexed: 02/07/2023]
Abstract
The GTPase RhoA is essential for the development of pre-T cells in the thymus. To investigate the mechanisms used by RhoA to control thymocyte development we have used Affymetrix gene profiling to identify RhoA regulated genes in T cell progenitors. The data show that RhoA plays a specific and essential role in pre-T cells because it is required for the expression of transcription factors of the Egr-1 and AP-1 families that have critical functions in thymocyte development. Loss of RhoA function in T cell progenitors causes a developmental block that pheno-copies the consequence of losing pre-TCR expression in Recombinase gene 2 (Rag2) null mice. Transcriptional profiling reveals both common and unique gene targets for RhoA and the pre-TCR indicating that RhoA participates in the pre-TCR induced transcriptional program but also mediates pre-TCR independent gene transcription.
Collapse
Affiliation(s)
- M. Mullin
- Samuel Lunenfeld Research Institute, 600 University Avenue, Toronto, Ont., Canada M5G 1X5
| | - K. Lightfoot
- University of Dundee/WTB, Division of Cell Biology and Immunology, Dow Street, Dundee DD15EH, United Kingdom
| | - R. Clarke
- University of Dundee/WTB, Division of Cell Biology and Immunology, Dow Street, Dundee DD15EH, United Kingdom
| | - M. Miller
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, P.O. Box 123, FIN-20521 Turku, Finland
| | - R. Lahesmaa
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, P.O. Box 123, FIN-20521 Turku, Finland
| | - D. Cantrell
- University of Dundee/WTB, Division of Cell Biology and Immunology, Dow Street, Dundee DD15EH, United Kingdom
- Corresponding author. Fax: +44 1382 345783.
| |
Collapse
|
13
|
Petrie HT, Zúñiga-Pflücker JC. Zoned out: functional mapping of stromal signaling microenvironments in the thymus. Annu Rev Immunol 2007; 25:649-79. [PMID: 17291187 DOI: 10.1146/annurev.immunol.23.021704.115715] [Citation(s) in RCA: 339] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
All hematopoietic cells, including T lymphocytes, originate from stem cells that reside in the bone marrow. Most hematopoietic lineages also mature in the bone marrow, but in this respect, T lymphocytes differ. Under normal circumstances, most T lymphocytes are produced in the thymus from marrow-derived progenitors that circulate in the blood. Cells that home to the thymus from the marrow possess the potential to generate multiple T and non-T lineages. However, there is little evidence to suggest that, once inside the thymus, they give rise to anything other than T cells. Thus, signals unique to the thymic microenvironment compel multipotent progenitors to commit to the T lineage, at the expense of other potential lineages. Summarizing what is known about the signals the thymus delivers to uncommitted progenitors, or to immature T-committed progenitors, to produce functional T cells is the focus of this review.
Collapse
Affiliation(s)
- Howard T Petrie
- Scripps Florida Research Institute, Jupiter, Florida 33458, USA.
| | | |
Collapse
|
14
|
Mullin MJ, Lightfoot K, Marklund U, Cantrell DA. Differential requirement for RhoA GTPase depending on the cellular localization of protein kinase D. J Biol Chem 2006; 281:25089-96. [PMID: 16772297 DOI: 10.1074/jbc.m603591200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
This study explores the links between the GTPase RhoA and the serine kinase protein kinase D (PKD) during thymocyte development. The rationale is that RhoA and PKD regulate common biological responses during T cell development, but there is nothing known about their interdependence. In fibroblasts, Rho function is required for activation of PKD catalytic activity. However, the data show that activation of Rho is neither sufficient nor essential for PKD activation in T cells. One alternative explanation for the apparent convergence of PKD and Rho signaling in T cells is that PKD responses might be Rho-dependent. To address this latter possibility, we probed the Rho requirements for the actions of constitutively active PKD mutants in pre-T cells of transgenic mice. Active PKD can localize to either the plasma membrane or the cytosol, and we therefore compared the Rho requirements for the actions of membrane- or cytosol-localized PKD. Here we show that membrane-localized PKD regulation of pre-T cell differentiation is Rho-dependent, but the actions of cytosol-localized PKD are not. These studies demonstrate that a Rho requirement for PKD activation is not ubiquitous. Moreover, links between PKD and Rho are determined by the cellular location of PKD.
Collapse
Affiliation(s)
- Michael J Mullin
- Division of Cell Biology and Immunology, Wellcome Trust Biocentre, University of Dundee, Dundee UK DD1 5EH, Scotland, United Kingdom
| | | | | | | |
Collapse
|
15
|
Chaigne-Delalande B, Deuve L, Reuzeau E, Basoni C, Lafarge D, Varon C, Tatin F, Anies G, Garand R, Kramer I, Génot E. RhoGTPases and p53 are involved in the morphological appearance and interferon-alpha response of hairy cells. THE AMERICAN JOURNAL OF PATHOLOGY 2006; 168:562-73. [PMID: 16436670 PMCID: PMC1606488 DOI: 10.2353/ajpath.2006.050345] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hairy cell leukemia is an uncommon B-cell lymphoproliferative disease of unknown etiology in which tumor cells display characteristic microfilamentous membrane projections. Another striking feature of the disease is its exquisite sensitivity to interferon (IFN)-alpha. So far, none of the known IFN-alpha regulatory properties have explained IFN-alpha responsiveness nor have they taken into account the morphological characteristics of hairy cells. IFN-alpha profoundly alters cytoskeletal organization of hairy cells and causes reversion of the hairy appearance into a rounded morphology. Because cytoskeletal rearrangements are controlled by the Rho family of GTPases, we investigated the GTPase activation status in hairy cells and their regulation by IFN-alpha. Using immunolocalization techniques and biochemical assays, we demonstrate that hairy cells display high levels of active Cdc42 and Rac1 and that IFN-alpha down-regulates these activities. In sharp contrast, RhoA activity was low in hairy cells but was increased by IFN-alpha treatment. Finally, IFN-alpha-mediated morphological changes also implicated a p53-induced response. These observations shed light on the mechanism of action of IFN-alpha in hairy cell leukemia and are of potential relevance for the therapeutical applications of this cytokine.
Collapse
|
16
|
Kelly AP, Hinton HJ, Clarke RG, Cantrell DA. Phosphoinositide-dependent kinase l (PDK1) haplo-insufficiency inhibits production of alpha/beta (α/β) but not gamma delta (γ/δ) T lymphocytes. FEBS Lett 2006; 580:2135-40. [PMID: 16563390 DOI: 10.1016/j.febslet.2006.03.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2006] [Revised: 02/20/2006] [Accepted: 03/07/2006] [Indexed: 12/27/2022]
Abstract
In the present study, we have explored the impact of deleting a single allele of PDK1 in T cell progenitors on alpha/beta and gamma/delta T cell development. The data show that deleting a single allele of PDK1 allows differentiation of alpha/beta T cells but prevents their proliferative expansion in the thymus. Accordingly, mice with T cells that are haplo-insufficient for PDK1 have reduced numbers of thymocytes and alpha/beta peripheral T cells. T cell progenitors also give rise to gamma/delta T cells but in contrast to the loss of alpha/beta T cells in T-PDK1 null and haplo-insufficient mice, there were increased numbers of gamma/delta T cells. The production of alpha/beta T cells is dependent on the proliferative expansion of thymocytes and is determined by a balance between the frequency with which cells enter the proliferative phase of the cell cycle and rates of cell death. Herein, we show that PDK1 haplo-insufficient thymocytes have no defects in their ability to enter the cell cycle but show increased apoptosis. PDK1 thus plays a determining role in the development of alpha/beta T lymphocytes but does not limit gamma/delta T cell development.
Collapse
Affiliation(s)
- April P Kelly
- Division of Cell Biology and Immunology, School of Life Sciences, WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | | | | | | |
Collapse
|
17
|
Vielkind S, Gallagher-Gambarelli M, Gomez M, Hinton HJ, Cantrell DA. Integrin regulation by RhoA in thymocytes. THE JOURNAL OF IMMUNOLOGY 2005; 175:350-7. [PMID: 15972668 DOI: 10.4049/jimmunol.175.1.350] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The guanine nucleotide-binding protein Rho has essential functions in T cell development and is important for the survival and proliferation of T cell progenitors in the thymus. To explore the mechanisms used by RhoA to control thymocyte biology, the role of this GTPase in the regulation of integrin-mediated cell adhesion was examined. The data show that RhoA activation is sufficient to stimulate beta(1) and beta(2) integrin-mediated adhesion in murine thymocytes. RhoA is also needed for integrin activation in vivo as loss of Rho function impaired the ability of thymocytes to adhere to the extracellular matrix protein VCAM-1 and prevented integrin activation induced by the GTPases Rac-1 and Rap1A in vivo. The regulated activity of integrins is needed for cell motility and in the present study it was seen that RhoA activity is critical for integrin-mediated thymocyte migration to chemokines in vitro. Thus, RhoA has a critical role in regulating cell adhesion and migration during T cell development.
Collapse
Affiliation(s)
- Susina Vielkind
- Lymphocyte Activation Laboratory, Cancer Research U.K. London Research Institute, Lincoln's Inn Fields Laboratories, London, United Kingdom
| | | | | | | | | |
Collapse
|
18
|
Harenberg A, Girkontaite I, Giehl K, Fischer KD. The Lsc RhoGEF mediates signaling from thromboxane A2 to actin polymerization and apoptosis in thymocytes. Eur J Immunol 2005; 35:1977-86. [PMID: 15884057 DOI: 10.1002/eji.200425769] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Lsc RhoGEF (also known as p115-RhoGEF) is a GTP exchange factor (GEF), an activator of GTPases of the Rho family. Lsc has a RhoGEF domain specific for Rho GTPase and a regulator of G protein signaling (RGS) domain specific for Galpha(12/13) subunits. One G protein receptor that can couple to Galpha(12/13) subunits is the receptor for thromboxane A(2 )(TXA(2)), thromboxane-prostanoid (called TP), which is highly expressed in immature thymocytes. TXA(2) has been implicated in thymocyte apoptosis. We found that Lsc(-/-) mice on a BALB/c background show thymic hyperplasia due to increased numbers of thymocytes and that these numbers further increase with the age of the mice. To investigate a role for Lsc in TXA(2) signaling, we analyzed activation of primary thymocytes by TXA(2) in vitro. TXA(2)-induced apoptosis of double-positive thymocytes and Rho activation required Lsc, and TXA(2) stimulation of actin polymerization and cofilin phosphorylation required both Lsc and Rho kinase (ROCK). Additionally, in the absence of Lsc, phosphorylation of the survival kinase Akt in response to TXA(2) was greatly enhanced. Together, these data demonstrate that Lsc is essential for mediating TXA(2 )signaling involved in apoptosis and actin organization and suggest that TXA(2) regulates thymic cellularity via Lsc.
Collapse
Affiliation(s)
- Anke Harenberg
- Department of Physiological Chemistry, University of Ulm, Ulm, Germany
| | | | | | | |
Collapse
|
19
|
Collier FM, Gregorio-King CC, Gough TJ, Talbot CD, Walder K, Kirkland MA. Identification and characterization of a lymphocytic Rho-GTPase effector: rhotekin-2. Biochem Biophys Res Commun 2005; 324:1360-9. [PMID: 15504364 DOI: 10.1016/j.bbrc.2004.09.205] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2004] [Indexed: 01/19/2023]
Abstract
Rhotekin belongs to the group of proteins containing a Rho-binding domain that are target peptides (effectors) for the Rho-GTPases. We previously identified a novel cDNA with homology to human rhotekin and in this study we cloned and characterized the coding region of this novel 12-exon gene. The ORF encodes a 609 amino-acid protein comprising a Class I Rho-binding domain and pleckstrin homology (PH) domain. Cellular cDNA expression of this new protein, designated Rhotekin-2 (RTKN2), was shown in the cytosol and nucleus of CHO cells. Using bioinformatics and RTPCR we identified three major splice variants, which vary in both the Rho-binding and PH domains. Real-time PCR studies showed exclusive RTKN2 expression in pooled lymphocytes and further purification indicated sole expression in CD4(pos) T-cells and bone marrow-derived B-cells. Gene expression was increased in quiescent T-cells but negligible in activated proliferating cells. In malignant samples expression was absent in myeloid leukaemias, low in most B-cell malignancies and CD8(pos) T-cell malignancies, but very high in CD4(pos)/CD8(pos) T-lymphoblastic lymphoma. As the Rho family is critical in lymphocyte development and function, RTKN2 may play an important role in lymphopoiesis.
Collapse
Affiliation(s)
- F M Collier
- Douglas Hocking Research Institute, Barwon Health, The Geelong Hospital, Geelong, Victoria 3220, Australia.
| | | | | | | | | | | |
Collapse
|
20
|
Coffield VM, Helms WS, Jiang Q, Su L. Galpha13 mediates a signal that is essential for proliferation and survival of thymocyte progenitors. ACTA ACUST UNITED AC 2004; 200:1315-24. [PMID: 15534370 PMCID: PMC2211919 DOI: 10.1084/jem.20040944] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
G protein signaling via the Galpha12 family (Galpha12 and Galpha13) has not been well studied in T cells. To investigate whether Galpha12 and Galpha13 are involved in thymopoiesis, we expressed the regulator of G protein signaling domain of p115RhoGEF to inhibit Galpha12 and Galpha13 during thymopoiesis. Fetal thymus organ cultures seeded with p115DeltaDH-expressing progenitor cells showed impaired thymopoiesis with a block at the CD4-CD8-CD44-CD25+ (DN3) stage. Using Galpha13 or Galpha12 minigenes, we demonstrated that Galpha13, but not Galpha12, is required for thymopoiesis. T progenitor cells expressing p115DeltaDH showed reduced proliferation and increased cell death. T cell receptor stimulation of the fetal thymus organ cultures did not rescue the block. Overexpression of the antiapoptotic gene Bcl2 rescued the defect in DN3 cells and partially rescued T cell development. Therefore, Galpha13-mediated signaling is necessary in early thymocyte proliferation and survival.
Collapse
Affiliation(s)
- V McNeil Coffield
- Lineberger Comprehensive Cancer Center, Dept. of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7295, USA
| | | | | | | |
Collapse
|
21
|
Grady GC, Mason SM, Stephen J, Zúñiga-Pflücker JC, Michie AM. Cyclic adenosine 5'-monophosphate response element binding protein plays a central role in mediating proliferation and differentiation downstream of the pre-TCR complex in developing thymocytes. THE JOURNAL OF IMMUNOLOGY 2004; 173:1802-10. [PMID: 15265911 DOI: 10.4049/jimmunol.173.3.1802] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The roles played by specific transcription factors during the regulation of early T cell development remain largely undefined. Several key genes induced during the primary checkpoint of T cell development, beta-selection, contain cAMP response element sites within their enhancer-promoter region that are regulated by CREB activation. In this study, we show that CREB is constitutively phosphorylated in the thymus, but not the spleen. We also show that CREB is activated downstream of the pre-TCR complex, and that the induction of CREB activity is regulated by protein kinase C alpha- and ERK-MAPK-mediated signals. We addressed the importance of this activation by expressing a naturally occurring inhibitor of CREB, inducible cAMP early repressor in wild-type fetal liver-derived lymphoid progenitor cells, and assessed their developmental potential. Fetal thymic organ cultures reconstituted with cells constitutively expressing inducible cAMP early repressor displayed a delay in generating CD4(+)CD8(+) thymocytes and a decrease in cellularity compared with control fetal thymic organ cultures. Taken together, our studies establish that CREB plays a central role in relaying proliferation and differentiation signals from the pre-TCR complex into the nucleus in developing thymocytes.
Collapse
Affiliation(s)
- Gillian C Grady
- Division of Immunology, Infection, and Inflammation, University of Glasgow, Glasgow, Scotland, United Kingdom
| | | | | | | | | |
Collapse
|
22
|
Klinger MB, Guilbault B, Kay RJ. The RhoA- and CDC42-specific exchange factor Dbs promotes expansion of immature thymocytes and deletion of double-positive and single-positive thymocytes. Eur J Immunol 2004; 34:806-816. [PMID: 14991610 DOI: 10.1002/eji.200324400] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Specific members of the Rho family of GTPases exert unique influences on thymocyte proliferation, differentiation and deletion. Dbs is a guanine nucleotide exchange factor which is expressed throughout thymocyte development and is able to activate the Rho family GTPases CDC42, RhoA and RhoG. Transgenic mice expressing an activated form of Dbs had increased numbers of double-negative thymocytes. The Dbs transgene promoted expansion of double-negative thymocytes in the absence of pre-TCR, but had no effect on pre-TCR-dependent differentiation of double-negative thymocytes into double-positive thymocytes. Transgenic double-positive thymocytes were proliferative in vivo, but were also susceptible to apoptosis in vivo and in vitro. The transgenic single-positive thymocytes had attenuated proliferative responses following TCR ligation, and were depleted rather than expanded during culture in the presence of anti-CD3. When expressing a positively selectable TCR, transgenic double-positive thymocytes were increased in number and activated, but the output of single-positive thymocytes was reduced. Transgenic double-positive thymocytes were acutely sensitive to deletion by TCR ligation in vivo. These results indicate that activation of Dbs has the potential to promote proliferation throughout thymocyte development, but also sensitizes double-positive and single-positive thymocytes to deletion.
Collapse
Affiliation(s)
- Mark B Klinger
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
- present address: Department of Microbiology and Immunology, University of California San Francisco, 513 Parnassus Avenue, San Francisco, CA 94122, USA
| | - Benoit Guilbault
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Robert J Kay
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| |
Collapse
|
23
|
Wang G, Woods A, Sabari S, Pagnotta L, Stanton LA, Beier F. RhoA/ROCK Signaling Suppresses Hypertrophic Chondrocyte Differentiation. J Biol Chem 2004; 279:13205-14. [PMID: 14726536 DOI: 10.1074/jbc.m311427200] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Coordinated proliferation and differentiation of growth plate chondrocytes is required for normal growth and development of the endochondral skeleton, but little is known about the intracellular signal transduction pathways regulating these processes. We have investigated the roles of the GTPase RhoA and its effector kinases ROCK1/2 in hypertrophic chondrocyte differentiation. RhoA, ROCK1, and ROCK2 are expressed throughout chondrogenic differentiation. RhoA overexpression in chondrogenic ATDC5 cells results in increased proliferation and a marked delay of hypertrophic differentiation, as shown by decreased induction of alkaline phosphatase activity, mineralization, and expression of the hypertrophic markers collagen X, bone sialoprotein, and matrix metalloproteinase 13. These effects are accompanied by activation of cyclin D1 transcription and repression of the collagen X promoter by RhoA. In contrast, inhibition of Rho/ROCK signaling by the pharmacological inhibitor Y27632 inhibits chondrocyte proliferation and accelerates hypertrophic differentiation. Dominant-negative RhoA also inhibits induction of the cyclin D1 promoter by parathyroid hormone-related peptide. Finally, Y27632 treatment partially rescues the effects of RhoA overexpression. In summary, we identify the RhoA/ROCK signaling pathway as a novel and important regulator of chondrocyte proliferation and differentiation.
Collapse
Affiliation(s)
- Guoyan Wang
- Department of Physiology and Pharmacology, Canadian Institutes of Health Research Group in Skeletal Development and Remodeling, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | | | | | | | | | | |
Collapse
|
24
|
Rodríguez-Borlado L, Barber DF, Hernández C, Rodríguez-Marcos MA, Sánchez A, Hirsch E, Wymann M, Martínez-A C, Carrera AC. Phosphatidylinositol 3-kinase regulates the CD4/CD8 T cell differentiation ratio. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:4475-82. [PMID: 12707323 DOI: 10.4049/jimmunol.170.9.4475] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The signaling pathways that control T cell differentiation have only begun to be elucidated. Using T cell lines, it has been shown that class IA phosphatidylinositol 3-kinase (PI3K), a heterodimer composed of a p85 regulatory and a p110 catalytic subunit, is activated after TCR stimulation. Nonetheless, the contribution of p85/p110 PI3K isoforms in T cell development has not been described. Mice deficient in the other family of class I PI3K, p110gamma, which is regulated by G protein-coupled receptors, exhibit reduced thymus size. Here we examine T cell development in p110gamma-deficient mice and in mice expressing an activating mutation of the p85 regulatory subunit, p65(PI3K), in T cells. We show that p110gamma-deficient mice have a partial defect in pre-TCR-dependent differentiation, which is restored after expression of the p65(PI3K) activating mutation. Genetic alteration of both PI3K isoforms also affects positive selection; p110gamma deletion decreased and p65(PI3K) expression augmented the CD4(+)/CD8(+) differentiation ratio. Finally, data are presented showing that both PI3K isoforms influenced mature thymocyte migration to the periphery. These observations underscore the contribution of PI3K in T cell development, as well as its implication in determining the CD4(+)/CD8(+) T cell differentiation ratio in vivo.
Collapse
Affiliation(s)
- Luis Rodríguez-Borlado
- Department of Immunology and Oncology, Centro Nacional de Biotecnología, Universidad Autónoma, Cantoblanco, Madrid, Spain
| | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Abstract
Guanine nucleotide binding proteins rapidly cycle between a guanosine diphosphate (GDP)-bound and guanosine triphosphate (GTP)-bound state, and they operate as binary switches that control cell activation in response to environmental cues. GTPases adopt different conformations when binding GTP vs. GDP. The GTP-bound state is generally considered to be the active conformation that allows GTPases to interact with downstream effectors and thereby initiate downstream signaling pathways, which regulate many important biological processes. Many members of the Ras family of GTPases, notably Ras and Rap1A, and the Rho family GTPases, Cdc42Hs, Rac1, Rac2 and RhoA, are important components of signal transduction pathways used by antigen receptors, costimulatory, cytokine and chemokine receptors to regulate the immune response. This review discusses current knowledge and ideas about the regulation and function of these GTPases in lymphocytes.
Collapse
Affiliation(s)
- Doreen Ann Cantrell
- Division of Cell Biology and Immunology, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee, UK.
| |
Collapse
|
26
|
Abstract
The specificity of the adaptive immune response is, in part, dependent on the clonal expression of the mature T cell receptor (TCR) on T lymphocytes. One mechanism regulating the clonality of the TCR occurs at the level of TCR-beta gene rearrangements during lymphocyte development. Expression of a nascent TCR-beta chain together with pre-Talpha (pTalpha) and CD3 molecules to form the pre-TCR complex, represents a critical checkpoint in T cell differentiation known as beta-selection. Indeed, failure to generate a functionally rearranged TCR-beta chain at this stage of development results in apoptosis. Signals derived from the pre-TCR complex trigger a maturation program within developing thymocytes that includes: rescue from apoptosis; inhibition of further DNA recombination at the TCR-beta gene locus (allowing for the clonality of antigen receptor expression; allelic exclusion); and induction of proliferation and differentiation. The signaling mechanisms that control this developmental program remain largely undefined. Here, we discuss recent evidence investigating the molecular mechanisms that regulate thymocyte differentiation downstream of pre-TCR formation.
Collapse
Affiliation(s)
- Alison M Michie
- Department of Immunology and Bacteriology, Western Infirmary, University of Glasgow, Glasgow, Scotland, G11 6NT, UK
| | | |
Collapse
|
27
|
Abstract
This review examines the value of transgenic studies in mice for the genetic dissection of signal-transduction pathways relevant to thymus development. T-cell development in the thymus is controlled by an ordered sequence of differentiation and proliferation checkpoints that culminate in the production of correctly selected, non-autoreactive, peripheral T lymphocytes. Work in transgenic mice has been fundamental for the preparation of genetic maps of signal-transduction pathways that control T-cell development. This review discusses how tyrosine kinases, guanine-nucleotide-binding proteins and transcription factors converge to control T-cell differentiation and proliferation in the immune system.
Collapse
Affiliation(s)
- Doreen A Cantrell
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, Lincoln's Inn Fields, London, UK.
| |
Collapse
|
28
|
Morgan MM, Labno CM, Van Seventer GA, Denny MF, Straus DB, Burkhardt JK. Superantigen-induced T cell:B cell conjugation is mediated by LFA-1 and requires signaling through Lck, but not ZAP-70. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:5708-18. [PMID: 11698443 DOI: 10.4049/jimmunol.167.10.5708] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The formation of a conjugate between a T cell and an APC requires the activation of integrins on the T cell surface and remodeling of cytoskeletal elements at the cell-cell contact site via inside-out signaling. The early events in this signaling pathway are not well understood, and may differ from the events involved in adhesion to immobilized ligands. We find that conjugate formation between Jurkat T cells and EBV-B cells presenting superantigen is mediated by LFA-1 and absolutely requires Lck. Mutations in the Lck kinase, Src homology 2 or 3 domains, or the myristoylation site all inhibit conjugation to background levels, and adhesion cannot be restored by the expression of Fyn. However, ZAP-70-deficient cells conjugate normally, indicating that Lck is required for LFA-1-dependent adhesion via other downstream pathways. Several drugs that inhibit T cell adhesion to ICAM-1 immobilized on plastic, including inhibitors of mitogen-activated protein/extracellular signal-related kinase kinase, phosphatidylinositol-3 kinase, and calpain, do not inhibit conjugation. Inhibitors of phospholipase C and protein kinase C block conjugation of both wild-type and ZAP-70-deficient cells, suggesting that a phospholipase C that does not depend on ZAP-70 for its activation is involved. These results are not restricted to Jurkat T cells; Ag-specific primary T cell blasts behave similarly. Although the way in which Lck signals to enhance LFA-1-dependent adhesion is not clear, we find that cells lacking functional Lck fail to recruit F-actin and LFA-1 to the T cell:APC contact site, whereas ZAP-70-deficient cells show a milder phenotype characterized by disorganized actin and LFA-1 at the contact site.
Collapse
Affiliation(s)
- M M Morgan
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
| | | | | | | | | | | |
Collapse
|
29
|
Gomez M, Kioussis D, Cantrell DA. The GTPase Rac-1 controls cell fate in the thymus by diverting thymocytes from positive to negative selection. Immunity 2001; 15:703-13. [PMID: 11728333 DOI: 10.1016/s1074-7613(01)00235-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The positive selection of CD4 or CD8 single-positive mature peripheral T lymphocytes and the deletion of self-reactive cells are crucial for central tolerance in the peripheral immune system. Previously, the guanine nucleotide binding protein Rac-1 has been shown to control pre-T cell development. The present report now describes the actions of Rac-1 in thymocyte selection. The study reveals that this molecule has the striking and unique ability to efficiently divert cells from positive selection into a pathway of negative selection and deletion. The ability of Rac-1 to switch thymocytes from a destiny of positive to negative selection identifies this molecule as a critical regulator of the developmental processes in T cells that are essential for immune homeostasis.
Collapse
Affiliation(s)
- M Gomez
- Imperial Cancer Research Fund, Lymphocyte Activation Laboratory, 44 Lincoln's Inn Fields, London, WC2A 3PX, United Kingdom
| | | | | |
Collapse
|
30
|
Corre I, Gomez M, Vielkind S, Cantrell DA. Analysis of thymocyte development reveals that the GTPase RhoA is a positive regulator of T cell receptor responses in vivo. J Exp Med 2001; 194:903-14. [PMID: 11581313 PMCID: PMC2193481 DOI: 10.1084/jem.194.7.903] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Loss of function of the guanine nucleotide binding protein RhoA blocks pre-T cell differentiation and survival indicating that this GTPase is a critical signaling molecule during early thymocyte development. Previous work has shown that the Rho family GTPase Rac-1 can initiate changes in actin dynamics necessary and sufficient for pre-T cell development. The present data now show that Rac-1 actions in pre-T cells require Rho function but that RhoA cannot substitute for Rac-1 and induce the actin cytoskeletal changes necessary for pre-T cell development. Activation of Rho is thus not sufficient to induce pre-T cell differentiation or survival in the absence of the pre-T cell receptor (TCR). The failure of RhoA activation to impact on pre-TCR-mediated signaling was in marked contrast to its actions on T cell responses mediated by the mature TCR alpha/beta complex. Cells expressing active RhoA were thus hyperresponsive in the context of TCR-induced proliferation in vitro and in vivo showed augmented positive selection of thymocytes expressing defined TCR complexes. This reveals that RhoA function is not only important for pre-T cells but also plays a role in determining the fate of mature T cells.
Collapse
Affiliation(s)
- Isabelle Corre
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, London, WC2A 3PX, UK
| | - Manuel Gomez
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, London, WC2A 3PX, UK
| | - Susina Vielkind
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, London, WC2A 3PX, UK
| | - Doreen A. Cantrell
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, London, WC2A 3PX, UK
| |
Collapse
|
31
|
Jacobs H. TCR-independent T cell development mediated by gain-of-oncogene function or loss-of-tumor-suppressor gene function. Semin Immunol 2000; 12:487-502. [PMID: 11085181 DOI: 10.1006/smim.2000.0262] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mechanisms that govern differentiation of T cell precursors during intrathymic development bridge an interdisciplinary research field of immunology, oncology and developmental biology. Critical checkpoints controlling early thymic T cell development and homeostasis are set by the proper signaling function of the IL-7 receptor, c-Kit receptor, and the pre-T cell antigen receptor (pre-TCR). Given the intimate link between cell cycle control and differentiation in T cell development, proto-oncogenes and tumor suppressors participate as physiological effectors downstream of these receptors not only to influence the cell cycle but also to determine differentiation and survival. Gain- or loss-of-function mutations of these downstream effectors uncouples partially or completely T cell precursors from these checkpoints, providing a selective advantage and enabling aberrant development. These effectors can be identified by provirus tagging in normal mice and more readily by complementation tagging in mice with a predefined block in T cell differentiation.
Collapse
Affiliation(s)
- H Jacobs
- Basel Institute for Immunology, Switzerland
| |
Collapse
|
32
|
Costello PS, Cleverley SC, Galandrini R, Henning SW, Cantrell DA. The GTPase rho controls a p53-dependent survival checkpoint during thymopoiesis. J Exp Med 2000; 192:77-85. [PMID: 10880528 PMCID: PMC1887705 DOI: 10.1084/jem.192.1.77] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
During the early stages of thymopoiesis, cell survival is controlled by cytokines that regulate the expression of antiapoptotic proteins such as Bcl-2. At the pre-T cell stage, a critical checkpoint for beta chain selection is monitored by the tumor suppressor p53: pre-T cells can survive and differentiate when p53 is removed genetically or when its proapoptotic function is inactivated physiologically as a consequence of signaling through the pre-T cell receptor complex. Previous work has shown that the guanine nucleotide binding protein Rho controls cell survival in T cell progenitors. Here we define the survival pathways controlled by Rho in pre-T cells and show that this GTPase is a pivotal regulator of the p53-mediated checkpoint operating at the time of beta selection: loss of Rho function results in apoptosis in pre-T cells, but this cell death is prevented by loss of p53. The prevention of cell death by loss of p53 restored numbers of early T cell progenitors but did not fully restore thymic cellularity. Further analysis revealed that loss of Rho function caused survival defects in CD4/8 double-positive thymocytes that is independent of p53 but can be prevented by ectopic expression of Bcl-2. These studies highlight that the GTPase Rho is a crucial component of survival signaling pathways in at least two different thymocyte subpopulations: Rho controls the p53 survival checkpoint in pre-T cells and is also crucial for a p53 independent survival signaling pathway in CD4/8 double positives.
Collapse
Affiliation(s)
- Patrick S. Costello
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, London WC2A 3PX, United Kingdom
| | - Steve C. Cleverley
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, London WC2A 3PX, United Kingdom
| | - Ricciarda Galandrini
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, London WC2A 3PX, United Kingdom
| | - Stefan W. Henning
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, London WC2A 3PX, United Kingdom
| | - Doreen A. Cantrell
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, London WC2A 3PX, United Kingdom
| |
Collapse
|
33
|
Abstract
Recent studies have begun to unravel some of the molecular pathways that appear to control the processes of T cell determination in the earliest thymocyte precursors. In addition, the analyses of mouse mutants with an entirely alymphoid thymus have shed light on the developmental relationship of pro-T cells and thymic dendritic cells, revealing that development of thymocytes and thymic dendritic cells can be dissociated.
Collapse
Affiliation(s)
- J P Di Santo
- Unité des Cytokines et Développement Lymphoïde, Institut Pasteur, Paris, F-75724, France.
| | | | | |
Collapse
|