51
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Trampont P, Zhang L, Ravichandran KS. ShcA mediates the dominant pathway to extracellular signal-regulated kinase activation during early thymic development. Mol Cell Biol 2006; 26:9035-44. [PMID: 16982683 PMCID: PMC1636838 DOI: 10.1128/mcb.00988-06] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
During thymic development, the beta selection checkpoint is regulated by pre-T-cell receptor-initiated signals. Progression through this checkpoint is influenced by phosphorylation and activation of the serine/threonine kinases extracellular signal-regulated kinase 1 (ERK1) and ERK2, but the in vivo relevance of specific upstream players leading to ERK activation is not known. Here, using mice with a conditional loss of the shc1 gene or expressing mutants of ShcA, we demonstrate that the adapter protein ShcA is responsible for up to 70% of ERK activation in double-negative (DN) thymocytes in vivo and ex vivo. We also identify two specific tyrosines on ShcA that promote ERK phosphorylation in vivo, and mice expressing ShcA with mutations of these tyrosines show impaired DN thymocyte development. This work provides the first in vivo demonstration of the relative requirement of upstream adapters in controlling ERK activation during beta selection and suggests a dominant role for ShcA.
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Affiliation(s)
- Paul Trampont
- Carter Immunology Center, MR4-4072D, Box 801386, University of Virginia, Charlottesville, VA 22908, USA
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52
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Lauritsen JPH, Haks MC, Lefebvre JM, Kappes DJ, Wiest DL. Recent insights into the signals that control alphabeta/gammadelta-lineage fate. Immunol Rev 2006; 209:176-90. [PMID: 16448543 DOI: 10.1111/j.0105-2896.2006.00349.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
During thymopoiesis, two major types of mature T cells are generated that can be distinguished by the clonotypic subunits contained within their T-cell receptor (TCR) complexes: alphabeta T cells and gammadelta T cells. Although there is no consensus as to the exact developmental stage where alphabeta and gammadelta T-cell lineages diverge, gammadelta T cells and precursors to the alphabeta T-cell lineage (bearing the pre-TCR) are thought to be derived from a common CD4- CD8- double-negative precursor. The role of the TCR in alphabeta/gammadelta lineage commitment has been controversial, in particular whether different TCR isotypes intrinsically favor adoption of the corresponding lineage. Recent evidence supports a signal strength model of lineage commitment, whereby stronger signals promote gammadelta development and weaker signals promote adoption of the alphabeta fate, irrespective of the TCR isotype from which the signals originate. Moreover, differences in the amplitude of activation of the extracellular signal-regulated kinase- mitogen-activated protein kinase-early growth response pathway appear to play a critical role. These findings will be placed in context of previous analyses in an effort to more precisely define the signals that control T-lineage fate during thymocyte development.
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Affiliation(s)
- Jens Peter H Lauritsen
- Fox Chase Cancer Center, Division of Basic Sciences, Immunobiology Working Group, Philadelphia, PA 19111, USA
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53
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David-Fung ES, Yui MA, Morales M, Wang H, Taghon T, Diamond RA, Rothenberg EV. Progression of regulatory gene expression states in fetal and adult pro-T-cell development. Immunol Rev 2006; 209:212-36. [PMID: 16448545 PMCID: PMC4157939 DOI: 10.1111/j.0105-2896.2006.00355.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Precursors entering the T-cell developmental pathway traverse a progression of states characterized by distinctive patterns of gene expression. Of particular interest are regulatory genes, which ultimately control the dwell time of cells in each state and establish the mechanisms that propel them forward to subsequent states. Under particular genetic and developmental circumstances, the transitions between these states occur with different timing, and environmental feedbacks may shift the steady-state accumulations of cells in each state. The fetal transit through pro-T-cell stages is faster than in the adult and subject to somewhat different genetic requirements. To explore causes of such variation, this review presents previously unpublished data on differentiation gene activation in pro-T cells of pre-T-cell receptor-deficient mutant mice and a quantitative comparison of the profiles of transcription factor gene expression in pro-T-cell subsets of fetal and adult wildtype mice. Against a background of consistent gene expression, several regulatory genes show marked differences between fetal and adult expression profiles, including those encoding two basic helix-loop-helix antagonist Id factors, the Ets family factor SpiB and the Notch target gene Deltex1. The results also reveal global differences in regulatory alterations triggered by the first T-cell receptor-dependent selection events in fetal and adult thymopoiesis.
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54
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Abstract
Deltex1, Deltex2, and Deltex4 form a family of related proteins that are the mammalian homologues of Drosophila Deltex, a known regulator of Notch signals. Deltex1 is highly induced by Notch signaling in thymocytes, and overexpression of Deltex1 in T-cell progenitors can block Notch signals, suggesting that Deltex1 may play an important role in regulating Notch signals during T-cell development. A recent report found that T cells develop normally in mice carrying a targeted deletion in the Deltex1 gene (S. Storck, F. Delbos, N. Stadler, C. Thirion-Delalande, F. Bernex, C. Verthuy, P. Ferrier, J. C. Weill, and C. A. Reynaud, Mol. Cell. Biol. 25: 1437-1445, 2005), suggesting that other Deltex homologues may compensate in Deltex1-deficient T cells. We generated mice that lack expression of both Deltex1 and Deltex2 by gene targeting and further reduced expression of Deltex4 in Deltex1/Deltex2 double-deficient T-cell progenitors using RNA interference. Using a sensitive in vitro assay, we found that Notch signaling is more potent in cells expressing lower levels of Deltex proteins. Nevertheless, we were unable to detect any significant defects in thymocyte maturation in Deltex1/Deltex2 double-knockout mice. Together these data suggest that Deltex can act as a negative regulator of Notch signals in T cells but that endogenous levels of Deltex1 and Deltex2 are not important for regulating Notch signals during thymocyte development.
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Affiliation(s)
- Sophie M Lehar
- Department of Immunology and Howard Hughes Medical Institute, University of Washington, I-604D Health Science Center, 1959 NE Pacific Street, Seattle, WA 98195, USA
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55
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Fernández-Malavé E, Wang N, Pulgar M, Schamel WWA, Alarcón B, Terhorst C. Overlapping functions of human CD3delta and mouse CD3gamma in alphabeta T-cell development revealed in a humanized CD3gamma-mouse. Blood 2006; 108:3420-7. [PMID: 16888097 DOI: 10.1182/blood-2006-03-010850] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Humans lacking the CD3gamma subunit of the pre-TCR and TCR complexes exhibit a mild alphabeta T lymphopenia, but have normal T cells. By contrast, CD3gamma-deficient mice are almost devoid of mature alphabeta T cells due to an early block of intrathymic development at the CD4(-)CD8(-) double-negative (DN) stage. This suggests that in humans but not in mice, the highly related CD3delta chain replaces CD3gamma during alphabeta T-cell development. To determine whether human CD3delta (hCD3delta) functions in a similar manner in the mouse in the absence of CD3gamma, we introduced an hCD3delta transgene in mice that were deficient for both CD3delta and CD3gamma, in which thymocyte development is completely arrested at the DN stage. Expression of hCD3delta efficiently supported pre-TCR-mediated progression from the DN to the CD4(+)CD8(+) double-positive (DP) stage. However, alphabetaTCR-mediated positive and negative thymocyte selection was less efficient than in wild-type mice, which correlated with a marked attenuation of TCR-mediated signaling. Of note, murine CD3gamma-deficient TCR complexes that had incorporated hCD3delta displayed abnormalities in structural stability resembling those of T cells from CD3gamma-deficient humans. Taken together, these data demonstrate that CD3delta and CD3gamma play a different role in humans and mice in pre-TCR and TCR function during alphabeta T-cell development.
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Affiliation(s)
- Edgar Fernández-Malavé
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
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56
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Jackson AM, Krangel MS. A role for MAPK in feedback inhibition of Tcrb recombination. THE JOURNAL OF IMMUNOLOGY 2006; 176:6824-30. [PMID: 16709842 DOI: 10.4049/jimmunol.176.11.6824] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The Tcrb locus is subject to a host of regulatory mechanisms that impart a strict cell and developmental stage-specific order to variable (V), diversity (D), and joining (J) gene segment recombination. The Tcrb locus is also regulated by allelic exclusion mechanisms, which restrict functional rearrangements to a single allele. The production of a functional rearrangement in CD4-CD8- double-negative (DN) thymocytes leads to the assembly of a pre-TCR and initiates signaling cascades that allow for DN to CD4+CD8+ double-positive (DP) differentiation, proliferation, and feedback inhibition of further Vbeta to DJbeta rearrangement. Feedback inhibition is believed to be controlled, in part, by the loss of Vbeta gene segment accessibility during the DN to DP transition. However, the pre-TCR signaling pathways that lead to the inactivation of Vbeta chromatin have not been determined. Because activation of the MAPK pathway is documented to promote DP differentiation in the absence of allelic exclusion, we characterized the properties of Vbeta chromatin within DP thymocytes generated by a constitutively active Raf1 (Raf-CAAX) transgene. Consistent with previous reports, we show that the Raf-CAAX transgene does not inhibit Tcrb recombination in DN thymocytes. Nevertheless, DP thymocytes generated by Raf-CAAX signals display normal down-regulation of Vbeta segment accessibility and normal feedback inhibition of the Vbeta to DJbeta rearrangement. Therefore, our results emphasize the distinct requirements for feedback inhibition in the DN and DP compartments. Although MAPK activation cannot impose feedback in DN thymocytes, it contributes to feedback inhibition through developmental changes that are tightly linked to DN to DP differentiation.
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MESH Headings
- Adaptor Proteins, Signal Transducing/deficiency
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/physiology
- Alleles
- Animals
- Chromatin/chemistry
- Chromatin/genetics
- Down-Regulation/genetics
- Down-Regulation/immunology
- Feedback, Physiological/genetics
- Feedback, Physiological/immunology
- Gene Rearrangement, beta-Chain T-Cell Antigen Receptor
- Humans
- Membrane Proteins/deficiency
- Membrane Proteins/genetics
- Membrane Proteins/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Phosphoproteins/deficiency
- Phosphoproteins/genetics
- Phosphoproteins/physiology
- Protein Prenylation
- Proto-Oncogene Proteins c-raf/genetics
- Proto-Oncogene Proteins c-raf/physiology
- Receptors, Antigen, T-Cell, alpha-beta/antagonists & inhibitors
- Receptors, Antigen, T-Cell, alpha-beta/biosynthesis
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Signal Transduction/genetics
- Signal Transduction/immunology
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- Thymus Gland/cytology
- Thymus Gland/immunology
- Thymus Gland/metabolism
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Affiliation(s)
- Annette M Jackson
- Department of Immunology, Duke University Medical Center, Durham NC 27710, USA
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57
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Graux C, Cools J, Michaux L, Vandenberghe P, Hagemeijer A. Cytogenetics and molecular genetics of T-cell acute lymphoblastic leukemia: from thymocyte to lymphoblast. Leukemia 2006; 20:1496-510. [PMID: 16826225 DOI: 10.1038/sj.leu.2404302] [Citation(s) in RCA: 214] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
For long, T-cell acute lymphoblastic leukemia (T-ALL) remained in the shadow of precursor B-ALL because it was more seldom, and showed a normal karyotype in more than 50% of cases. The last decennia, intense research has been carried out on different fronts. On one side, development of normal thymocyte and its regulation mechanisms have been studied in multiple mouse models and subsequently validated. On the other side, molecular cytogenetics (fluorescence in situ hybridization) and mutation analysis revealed cytogenetically cryptic aberrations in almost all cases of T-ALL. Also, expression microarray analysis disclosed gene expression signatures that recapitulate specific stages of thymocyte development. Investigations are still very much actual, fed by the discovery of new genetic aberrations. In this review, we present a summary of the current cytogenetic changes associated with T-ALL. The genes deregulated by translocations or mutations appear to encode proteins that are also implicated in T-cell development, which prompted us to review the 'normal' and 'leukemogenic' functions of these transcription regulators. To conclude, we show that the paradigm of multistep leukemogenesis is very much applicable to T-ALL and that the different genetic insults collaborate to maintain self-renewal capacity, and induce proliferation and differentiation arrest of T-lymphoblasts. They also open perspectives for targeted therapies.
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Affiliation(s)
- C Graux
- Department of Hematology, Cliniques Universitaires St Luc, Catholic University of Louvain, Brussels, Belgium
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58
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Yamamoto R, Uenishi H, Yasue H, Takagaki Y, Sato E. The genomic structure and a novel alternatively spliced form of porcine pTalpha chain. Mol Immunol 2006; 44:591-7. [PMID: 16712934 DOI: 10.1016/j.molimm.2006.02.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Revised: 02/04/2006] [Accepted: 02/07/2006] [Indexed: 12/28/2022]
Abstract
A complete genomic nucleotide sequence for porcine pTalpha gene was obtained from a BAC clone, which revealed a novel exon 2 missing in human and murine counterparts. Cattle and dog genomic sequences showed the counterparts corresponding to porcine exon 2. Using thymocyte RNA and RT-PCR, three types of porcine pTalpha-chain cDNA sequences, pTalpha1, pTalpha2 and pTalpha3, were obtained. These three different cDNA sequences were alternatively spliced products with pTalpha1 consisting of exons 1, 2, 3, 4, and 5, pTalpha2 consisting of exons 1, 2, 4, and 5, and pTalpha3 consisting of exons 1, 2, 3 and the intron down stream of exon 3. pTalpha1 and pTalpha2 correspond to previously reported pTalphaa, and pTalphab, respectively, and pTalpha3 is reported for the first time. Using RT-PCR, pTalpha3 appeared expressed predominantly in the thymocyte RNA. The chromosome location of pTalpha was investigated using Radiation Hybrid Map and FISH, both of which revealed the location at SSC7q11-q12.
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Affiliation(s)
- Ryuji Yamamoto
- Genome Research Department, National Institute of Agrobiological Sciences, 2 Ikenodai, Tsukuba 305-8602, Japan
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59
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Taghon T, Yui MA, Pant R, Diamond RA, Rothenberg EV. Developmental and molecular characterization of emerging beta- and gammadelta-selected pre-T cells in the adult mouse thymus. Immunity 2006; 24:53-64. [PMID: 16413923 DOI: 10.1016/j.immuni.2005.11.012] [Citation(s) in RCA: 235] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Revised: 11/06/2005] [Accepted: 11/30/2005] [Indexed: 01/12/2023]
Abstract
The first checkpoint in T cell development, beta selection, has remained incompletely characterized for lack of specific surface markers. We show that CD27 is upregulated in DN3 thymocytes initiating beta selection, concomitant with intracellular TCR-beta expression. Clonal analysis determined that CD27high DN3 cells generate CD4+CD8+ progeny with more than 90% efficiency, faster and more efficiently than the CD27low majority. CD27 upregulation also occurs in gammadelta-selected DN3 thymocytes in TCR-beta-/- mice and in IL2-GFP transgenic reporter mice where GFP marks the earliest emerging TCR-gammadelta cells from DN3 thymocytes. With CD27 to distinguish pre- and postselection DN3 cells, a detailed gene expression analysis defined regulatory changes associated with checkpoint arrest, with beta selection, and with gammadelta selection. gammadelta selection induces higher CD5, Egr, and Runx3 expression as compared to beta selection, but it triggers less proliferation. Our results also reveal differences in Notch/Delta dependence at the earliest stages of divergence between developing alphabeta and gammadelta T-lineage cells.
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MESH Headings
- Animals
- CD4-Positive T-Lymphocytes/cytology
- CD4-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/cytology
- CD8-Positive T-Lymphocytes/immunology
- Cell Lineage/genetics
- Gene Expression Profiling
- Gene Expression Regulation, Developmental
- Interleukin-2/genetics
- Intracellular Signaling Peptides and Proteins
- Membrane Proteins/metabolism
- Mice
- Mice, Mutant Strains
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Receptors, Antigen, T-Cell, gamma-delta/genetics
- Receptors, Antigen, T-Cell, gamma-delta/metabolism
- Receptors, Notch/metabolism
- Stem Cells/cytology
- Stem Cells/immunology
- Thymus Gland/cytology
- Thymus Gland/growth & development
- Transgenes
- Tumor Necrosis Factor Receptor Superfamily, Member 7/analysis
- Tumor Necrosis Factor Receptor Superfamily, Member 7/metabolism
- Up-Regulation
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Affiliation(s)
- Tom Taghon
- Division of Biology, MC 156-29, California Institute of Technology, 1200 E California Boulevard, Pasadena, California 91125, USA
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60
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Penkov D, Di Rosa P, Fernandez Diaz L, Basso V, Ferretti E, Grassi F, Mondino A, Blasi F. Involvement of Prep1 in the alphabeta T-cell receptor T-lymphocytic potential of hematopoietic precursors. Mol Cell Biol 2006; 25:10768-81. [PMID: 16314502 PMCID: PMC1316969 DOI: 10.1128/mcb.25.24.10768-10781.2005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Prep1 is a homeodomain transcription factor that acts by dimerizing with Pbx. Since Prep1 null embryos die at gastrulation, we studied Prep1(i/i) hypomorphic mice to study the physiological role of Prep1. A low percentage of homozygous Prep1(i/i) mice survived at birth, and their postnatal functions could be investigated. Reduced Prep1 expression caused an abnormal thymic T-cell development: increased CD4(-) CD8(-) double-negative thymocytes, decrease in alphabetaTCR(high) cells (cells with high levels of the alphabetaTau-cell receptor [alphabetaTCR]) and CD4(+) and CD8(+) single-positive (SP) thymocytes, and increase in gammadeltaTCR cells. Peripheral lymphoid organs of Prep1(i/i) mice contained fewer alphabetaTCR mature T cells and more gammadeltaTCR T cells than wild-type littermates. Moreover, Prep1(i/i) CD4(+) CD8(+) double-positive thymocytes underwent more apoptosis, and SP thymocytes proliferated less than control littermates. Mice that were lethally irradiated and then had Prep1(i/i) fetal liver cells transplanted showed the same defects as the Prep1(i/i) mice did. Among PBC family members, Pbx2 and very low levels of Pbx3 were observed in the thymi of wild-type mice. In Prep1(i/i) mice, the level of Pbx2 protein was profoundly decreased, while for Pbx3 no definitive conclusion could be reached. Therefore, the deficient postnatal T-lymphocytic potential of the Prep1 hematopoietic progenitors depends on the combined, not compensated, absence of Prep1 and at least Pbx2.
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Affiliation(s)
- Dmitri Penkov
- Molecular Genetics Unit, Università Vita Salute San Raffaele, Milan, Italy
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61
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Lefebvre JM, Haks MC, Carleton MO, Rhodes M, Sinnathamby G, Simon MC, Eisenlohr LC, Garrett-Sinha LA, Wiest DL. Enforced Expression of Spi-B Reverses T Lineage Commitment and Blocks β-Selection. THE JOURNAL OF IMMUNOLOGY 2005; 174:6184-94. [PMID: 15879115 DOI: 10.4049/jimmunol.174.10.6184] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The molecular changes that restrict multipotent murine thymocytes to the T cell lineage and render them responsive to Ag receptor signals remain poorly understood. In this study, we report our analysis of the role of the Ets transcription factor, Spi-B, in this process. Spi-B expression is acutely induced coincident with T cell lineage commitment at the CD4(-)CD8(-)CD44(-)CD25(+) (DN3) stage of thymocyte development and is then down-regulated as thymocytes respond to pre-TCR signals and develop beyond the beta-selection checkpoint to the CD4(-)CD8(-)CD44(-)CD25(-) (DN4) stage. We found that dysregulation of Spi-B expression in DN3 thymocytes resulted in a dose-dependent perturbation of thymocyte development. Indeed, DN3 thymocytes expressing approximately five times the endogenous level of Spi-B were arrested at the beta-selection checkpoint, due to impaired induction of Egr proteins, which are important molecular effectors of the beta-selection checkpoint. T lineage-committed DN3 thymocytes expressing even higher levels of Spi-B were diverted to the dendritic cell lineage. Thus, we demonstrate that the prescribed modulation of Spi-B expression is important for T lineage commitment and differentiation beyond the beta-selection checkpoint; and we provide insight into the mechanism underlying perturbation of development when that expression pattern is disrupted.
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Affiliation(s)
- Juliette M Lefebvre
- Immunobiology Working Group, Division of Basic Sciences, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
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62
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Palacios EH, Weiss A. Function of the Src-family kinases, Lck and Fyn, in T-cell development and activation. Oncogene 2004; 23:7990-8000. [PMID: 15489916 DOI: 10.1038/sj.onc.1208074] [Citation(s) in RCA: 505] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The function of the Src-family kinases (SFKs) Lck and Fyn in T cells has been intensively studied over the past 15 years. Animal models and cell line studies both indicate a critical role for Lck and Fyn in proximal T-cell antigen receptor (TCR) signal transduction. Recruited SFKs phosphorylate TCR ITAMs (immunoreceptor tyrosine-based activation motifs) in the CD3 and zeta chains, which then serve as docking sites for Syk-family kinases. SFKs then phosphorylate and activate the recruited Syk-family kinase. Lck and Fyn are spatially segregated in cell membranes due to differential lipid raft localization, and may undergo sequential activation. In addition to the CD4 and CD8 coreceptors, a recently described adaptor, Unc119, may link SFKs to the TCR. CD45 and Csk provide positive and negative regulatory control of SFK functions, respectively, and Csk is constitutively bound to the transmembrane adapter protein, PAG/Cbp. TCR-based signaling is required at several stages of T-cell development, including at least pre-TCR signaling, positive selection, peripheral maintenance of naive T cells, and lymphopenia-induced proliferation. SFKs are required for each of these TCR-based signals, and Lck seems to be the major contributor.
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Affiliation(s)
- Emil H Palacios
- Rosalind Russell Medical Research Center for Arthritis, Department of Medicine and The Howard Hughes Medical Institute, University of California, San Francisco 94143-0795, USA
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63
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Klinger MB, Guilbault B, Goulding RE, Kay RJ. Deregulated expression of RasGRP1 initiates thymic lymphomagenesis independently of T-cell receptors. Oncogene 2004; 24:2695-704. [PMID: 15829980 DOI: 10.1038/sj.onc.1208334] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
RasGRP1 is a Ras-specific exchange factor, which is activated by T-cell receptor (TCR) and promotes TCR-dependent positive selection of thymocytes. RasGRP1 is highly expressed on most T lymphocytic leukemias and is a common site of proviral insertion in retrovirus-induced murine T-cell lymphomas. We used RasGRP1 transgenic mice to determine if deregulated expression of RasGRP1 has a causative role in the development of T-cell malignancies. Thymic lymphomas occurred in three different RasGRP1 transgenic mouse lines. Thymocyte transformation correlated with high transgene expression in early stage lymphomas, indicating that deregulated RasGRP1 expression contributed to the initiation of lymphomagenesis. Expression of the positively selectable H-Y TCR accelerated lymphomagenesis in RasGRP1 transgenic mice. However, the transformed thymocytes lacked markers of positive selection and lymphomas occurred when positive selection was precluded by negative selection of the H-Y TCR. Therefore, initiation of lymphomagenesis via RasGRP1 was not associated with TCR-dependent positive selection of thymocytes. Thymic lymphomas occurred in RasGRP1 transgenic/Rag2-/- mice, demonstrating that neither TCR nor pre-TCR were required for RasGRP1-driven lymphomagenesis. The RasGRP1 transgene conferred pre-TCR-independent survival and proliferation of immature thymocytes, suggesting that deregulated expression of RasGRP1 promotes lymphomagenesis by expanding the pool of thymocytes which are susceptible to transformation.
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Affiliation(s)
- Mark B Klinger
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
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64
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Yui MA, Rothenberg EV. Deranged Early T Cell Development in Immunodeficient Strains of Nonobese Diabetic Mice. THE JOURNAL OF IMMUNOLOGY 2004; 173:5381-91. [PMID: 15494484 DOI: 10.4049/jimmunol.173.9.5381] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
NOD mice exhibit defects in T cell functions that have been postulated to contribute to diabetes susceptibility in this strain. However, early T cell development in NOD mice has been largely unexplored. NOD mice with the scid mutation and Rag1 deficiency were analyzed for pre-T cell development in the NOD genetic background. These strains reveal an age-dependent, programmed breakdown in beta selection checkpoint enforcement. At 5-8 wk of age, even in the absence of TCRbeta expression, CD4+ and CD4+CD8+ blasts appear spontaneously. However, these breakthrough cells fail to restore normal thymic cellularity. The breakthrough phenotype is recessive in hybrid (NODxB6)F1-scid and -Rag1null mice. The breakthrough cells show a mosaic phenotype with respect to components of the beta selection program. They mimic normal beta selection by up-regulating germline TCR-Calpha transcripts, CD2, and Bcl-xL and down-regulating Bcl-2. However, they fail to down-regulate transcription factors HEB-alt and Hes1 and initially express aberrantly high levels of Spi-B, c-kit (CD117), and IL-7Ralpha. Other genes examined distinguish this form of breakthrough from previously reported models. Some of the abnormalities appear first in a cohort of postnatal thymocytes as early as the double-negative 2/double-negative 3 transitional stage. Thus, our results reveal an NOD genetic defect in T cell developmental programming and checkpoint control that permits a subset of the normal outcomes of pre-TCR signaling to proceed even in the absence of TCRbeta rearrangement. Furthermore, this breakthrough may initiate thymic lymphomagenesis that occurs with high frequency in both NOD-scid and -Rag1null mice.
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MESH Headings
- Aging/genetics
- Aging/immunology
- Animals
- CD2 Antigens/biosynthesis
- CD2 Antigens/genetics
- CD4 Antigens/biosynthesis
- Cell Cycle/genetics
- Cell Cycle/immunology
- Cell Differentiation/genetics
- Cell Differentiation/immunology
- Cell Division/genetics
- Cell Division/immunology
- Gene Expression Regulation/immunology
- Genes, RAG-1
- Genes, Recessive
- Genes, T-Cell Receptor alpha
- Lymphopenia/genetics
- Lymphopenia/immunology
- Lymphopenia/pathology
- Mice
- Mice, Inbred C57BL
- Mice, Inbred NOD
- Mice, Knockout
- Mice, SCID
- Mice, Transgenic
- Proto-Oncogene Proteins c-bcl-2/antagonists & inhibitors
- Proto-Oncogene Proteins c-bcl-2/biosynthesis
- Proto-Oncogene Proteins c-kit/biosynthesis
- Receptors, Interleukin-7/biosynthesis
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- T-Lymphocyte Subsets/pathology
- Thymus Gland/immunology
- Thymus Gland/metabolism
- Thymus Gland/pathology
- Transcription, Genetic
- Up-Regulation/immunology
- bcl-X Protein
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Affiliation(s)
- Mary A Yui
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA
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65
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Lehar SM, Dooley J, Farr AG, Bevan MJ. Notch ligands Delta 1 and Jagged1 transmit distinct signals to T-cell precursors. Blood 2004; 105:1440-7. [PMID: 15486060 PMCID: PMC2776671 DOI: 10.1182/blood-2004-08-3257] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Signaling through the Notch pathway plays an essential role in inducing T-lineage commitment and promoting the maturation of immature thymocytes. Using an in vitro culture system, we show that 2 different classes of Notch ligands, Jagged1 or Delta1, transmit distinct signals to T-cell progenitors. OP9 stromal cells expressing either Jagged1 or Delta1 inhibit the differentiation of DN1 thymocytes into the B-cell lineage, but only the Delta1-expressing stromal cells promote the proliferation and maturation of T-cell progenitors through the early double-negative (DN) stages of thymocyte development. Whereas the majority of bone marrow-derived stem cells do not respond to Jagged1 signals, T-cell progenitors respond to Jagged1 signals during a brief window of their development between the DN1 and DN3 stages of thymic development. During these stages, Jagged1 signals can influence the differentiation of immature thymocytes along the natural killer (NK) and gamma delta T-cell lineages.
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Affiliation(s)
- Sophie M Lehar
- Department of Immunology, University of Washington, Seattle, WA 98195, USA
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66
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Abstract
The basic helix-loop-helix transcription factors, E2A and HEB, play important roles in T-cell development at multiple checkpoints. Expression of their inhibitor, Id1, abolishes the function of both transcription factors in a dose-dependent manner. The Id1 transgenic thymus is characterized by an accumulation of CD4- CD8- CD44+ CD25- thymocytes, a dramatic reduction of CD4+ CD8+ thymocytes, and an abundance of apoptotic cells. Here we show that these apoptotic cells carry functional T-cell receptors (TCRs), suggesting that apoptosis occurs during T-cell maturation. In contrast, viable Id1 transgenic CD4 single positive T cells exhibit costimulation-independent proliferation upon treatment with anti-CD3 antibody, probably due to a hyperresponse to TCR signaling. Furthermore, Id1 expression causes apoptosis of CD4 and CD8 double- or single-positive thymocytes in HY- or AND-TCR transgenic mice under conditions that normally support positive selection. Collectively, these results suggest that E2A and HEB proteins are crucial for controlling the threshold for TCR signaling, and Id1 expression lowers the threshold, resulting in apoptosis of developing thymocytes.
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Affiliation(s)
- Zengbiao Qi
- Immunobiology and Cancer Program, Oklahoma Medical Research Foundation, University of Oklahoma Health Sciences Center, Oklahoma City 73104, USA
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67
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Abstract
Autoreactive antibodies are etiologic agents in a number of autoimmune diseases. Like all other antibodies these antibodies are produced in developing B cells by V(D)J recombination in the bone marrow. Three mechanisms regulate autoreactive B cells: deletion, receptor editing, and anergy. Here we review the prevalence of autoantibodies in the initial antibody repertoire, their regulation by receptor editing, and the role of the recombinase proteins (RAG1 and RAG2) in this process.
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Affiliation(s)
- Mila Jankovic
- Laboratory of Molecular Immunology, The Rockefeller University, New York, New York 10021, USA.
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68
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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.
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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
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69
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Engel I, Murre C. E2A proteins enforce a proliferation checkpoint in developing thymocytes. EMBO J 2003; 23:202-11. [PMID: 14685278 PMCID: PMC1271657 DOI: 10.1038/sj.emboj.7600017] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2003] [Accepted: 10/22/2003] [Indexed: 11/08/2022] Open
Abstract
E2A proteins regulate multiple stages of thymocyte development and suppress T-cell lymphoma. The activity of E2A proteins throughout thymocyte development is modulated by signals emanating from the pre-TCR and TCR. Here we demonstrate that E2A is required for the complete arrest in both differentiation and proliferation observed in thymocytes with defects in proteins that mediate pre-TCR signaling, including LAT, Lck and Fyn. We show that E2A proteins are required to prevent the accumulation of TCRbeta negative cells beyond the pre-TCR checkpoint. E2A-deficient thymocytes also exhibit abnormal cell-cycle progression prior to pre-TCR expression. Furthermore, we demonstrate that E47 can act in concert with Bcl-2 to induce cell-cycle arrest in vitro. These observations indicate that E2A proteins function during early thymocyte development to block cell-cycle progression prior to the expression of TCRbeta. In addition, these data provide further insight into how deficiencies in E2A lead to T lymphoma.
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Affiliation(s)
- Isaac Engel
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Cornelis Murre
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
- Department of Biology, 0366, University of California, San Diego Cancer Center, 9500 Gilman Drive, La Jolla, CA 92093-0366, USA. Tel.: +1 858 534 8796; Fax: +1 858 534 7550; E-mail:
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70
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Marklund U, Lightfoot K, Cantrell D. Intracellular Location and Cell Context-Dependent Function of Protein Kinase D. Immunity 2003; 19:491-501. [PMID: 14563314 DOI: 10.1016/s1074-7613(03)00260-7] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Protein kinase D (PKD) is an antigen receptor-activated serine kinase localized at either the plasma membrane or the cytosol of lymphocytes. To probe PKD function at these different locations, transgenesis was used to target active PKD either to the membrane or cytosol of pre-T cells. In recombinase gene null pre-T cells, membrane and cytosolic active PKD both induced differentiation reminiscent of beta selection: downregulation of CD25 and upregulation of CD2 and CD5. Active PKDs also induced pre-T cell proliferation, although this response was not universal to all thymocyte subsets. There were two striking differences between the actions of the differentially localized PKDs. Membrane but not cytosolic PKD could induce expression of CD8 and CD4 in recombinase null mice; cytosolic but not membrane PKD suppressed Vbeta to DJbeta rearrangements of the TCRbeta chain locus in wild-type T cells. PKD function is thus determined by its intracellular location and cell context.
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Affiliation(s)
- Ulrica Marklund
- Lymphocyte Activation Laboratory, Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, United Kingdom
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71
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Huang EY, Gallegos AM, Richards SM, Lehar SM, Bevan MJ. Surface expression of Notch1 on thymocytes: correlation with the double-negative to double-positive transition. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 171:2296-304. [PMID: 12928374 DOI: 10.4049/jimmunol.171.5.2296] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Notch1 plays a critical role in regulating T lineage commitment during the differentiation of lymphoid precursors. The physiological relevance of Notch1 signaling during subsequent stages of T cell differentiation has been more controversial. This is due in part to conflicting data from studies examining the overexpression or targeted deletion of Notch1 and to difficulties in distinguishing between the activities of multiple Notch family members and their ligands, which are expressed in the thymus. We employed a polyclonal antiserum against the extracellular domain of Notch1 to study surface expression during thymopoiesis. We found high levels of Notch1 on the cell surface only on double negative (DN) stage 2 through the immature single-positive stage of thymocyte development, before the double-positive (DP) stage. The Notch signaling pathway, as read out by Deltex1 expression levels, is highly active in DN thymocytes. When an active Notch1 transgene, Notch1IC, is exogenously introduced into thymocytes of recombinase-activating gene 2-deficient mice, it promotes proliferation and development to the DP stage following anti-CD3 treatment without apparently affecting the intensity of pre-TCR signaling. In addition, a stromal cell line expressing the Notch ligand, Delta-like-1, promotes the in vitro expansion of wild-type DN3 thymocytes in vitro. Consistent with other recent reports, these data suggest a role for Notch1 during the DN to DP stage of thymocyte maturation and suggest a cellular mechanism by which Notch1IC oncogenes could contribute to thymoma development and maintenance.
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Affiliation(s)
- Eugene Y Huang
- Department of Immunology, Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
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72
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Woods CC, Banks KE, Gruener R, DeLuca D. Loss of T cell precursors after spaceflight and exposure to vector-averaged gravity. FASEB J 2003; 17:1526-8. [PMID: 12824295 DOI: 10.1096/fj.02-0749fje] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Using fetal thymus organ culture (FTOC), we examined the effects of spaceflight and vector-averaged gravity on T cell development. Under both conditions, the development of T cells was significantly attenuated. Exposure to spaceflight for 16 days resulted in a loss of precursors for CD4+, CD8+, and CD4+CD8+ T cells in a rat/mouse xenogeneic co-culture. A significant decrease in the same precursor cells, as well as a decrease in CD4-CD8- T cell precursors, was also observed in a murine C57BL/6 FTOC after rotation in a clinostat to produce a vector-averaged microgravity-like environment. The block in T cell development appeared to occur between the pre-T cell and CD4+CD8+ T cell stage. These data indicate that gravity plays a decisive role in the development of T cells.
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Affiliation(s)
- Chris C Woods
- Department of Microbiology and Immunology, University of Arizona, Tucson, Arizona 85724, USA
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73
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Kaymaz FF, Dağdeviren A, Aşan E. Antigenic profile of human thymus in concurrence with "Clusters of Thymic Epithelial Staining" classification. Ann Anat 2003; 185:163-71. [PMID: 12725440 DOI: 10.1016/s0940-9602(03)80081-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined the expression of various CD coded or not yet defined antigens in human thymus samples using indirect immunoperoxidase and immunoflourescent techniques. Data obtained are presented in concurrence with Clusters of Thymic Epithelial Staining (CTES) classification for various monoclonal antibodies recognizing CD antigens (CD1, CD1a, CD6, CD9, CD14, CD16, CD29, CD30, CD32, CD44, CD45RB, CD47, CD48, CD49a, CD49b, CD49c, CD49d, CD49e, CD49f, CD51, CD53, CD54, CD56, CD57, CD63, CD85, CD95, CD98, CD102, CD103, CD106, CD109, CD146, CD147, CD148, CD151, CD152, CD158a, CD158b, CD164, CD165, CD166) and for monoclonal antibodies 1B10, 5G7, A4, BD46, BLTZ, HP1C5, IND.64, M72, WU947 whose specifities are not yet defined. Some of the mAbs such as CD49f, IND.64 and BD46 are detected as good markers for specific cell types or compartments. Significance of the presence of these antigens on thymic epithelial cells at certain locations is briefly discussed.
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Affiliation(s)
- F Figen Kaymaz
- Department of Histology and Embryology, Faculty of Medicine, Hacettepe University, 06100 Ankara, Turkey.
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74
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Asnafi V, Beldjord K, Boulanger E, Comba B, Le Tutour P, Estienne MH, Davi F, Landman-Parker J, Quartier P, Buzyn A, Delabesse E, Valensi F, Macintyre E. Analysis of TCR, pT alpha, and RAG-1 in T-acute lymphoblastic leukemias improves understanding of early human T-lymphoid lineage commitment. Blood 2003; 101:2693-703. [PMID: 12446444 DOI: 10.1182/blood-2002-08-2438] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
T-acute lymphoblastic leukemias (T-ALLs) derive from human T-lymphoid precursors arrested at various early stages of development. Correlation of phenotype and T-cell receptor (TCR) status with RAG-1 and pT alpha transcription in 114 T-ALLs demonstrated that they largely reflect physiologic T-lymphoid development. Half the TCR alpha beta lineage T-ALLs expressed a pre-TCR, as evidenced by RAG-1, pT alpha, and cTCR beta expression, absence of TCR delta deletion, and a sCD3(-), CD1a(+), CD4/8 double-positive (DP) phenotype, in keeping with a population undergoing beta selection. Most TCR gamma delta T-ALLs were pT alpha, terminal deoxynucleotidyl transferase (TdT), and RAG-1(lo/neg), double-negative/single-positive (DN/SP), and demonstrated only TCR beta DJ rearrangement, whereas 40% were pT alpha, TdT, and RAG-1 positive, DP, and demonstrated TCR beta V(D)J rearrangement, with cTCR beta expression in proportion. As such they may correspond to TCR alpha beta lineage precursors selected by TCR gamma delta expression, to early gamma delta cells recently derived from a pT alpha(+) common alpha beta/gamma delta precursor, or to a lineage-deregulated alpha beta/gamma delta intermediate. Approximately 30% of T-ALLs were sCD3/cTCR beta(-) and corresponded to nonrestricted thymic precursors because they expressed non-T-restricted markers such as CD34, CD13, CD33, and CD56 and were predominantly DN, CD1a, pT alpha, and RAG-1 low/negative, despite immature TCR delta and TCR gamma rearrangements. TCR gene configuration identified progressive T-lymphoid restriction. T-ALLs, therefore, provide homogeneous expansions of minor human lymphoid precursor populations that can aid in the understanding of healthy human T-cell development.
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MESH Headings
- Adolescent
- Adult
- Aged
- Antigens, CD/analysis
- Cell Lineage
- Child
- Genotype
- Homeodomain Proteins/genetics
- Humans
- Immunophenotyping
- Leukemia-Lymphoma, Adult T-Cell/classification
- Leukemia-Lymphoma, Adult T-Cell/immunology
- Leukemia-Lymphoma, Adult T-Cell/pathology
- Male
- Membrane Glycoproteins/genetics
- Middle Aged
- RNA, Messenger/analysis
- Receptors, Antigen, T-Cell/classification
- Receptors, Antigen, T-Cell, alpha-beta
- Receptors, Antigen, T-Cell, gamma-delta
- T-Lymphocytes/cytology
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Affiliation(s)
- Vahid Asnafi
- Department of Biological and Clinical Hematology, Centre Hospitalier-Universitaire/Assistance Publique-Hopitaux de Paris (CHU/AP-HP) Necker-Enfants Malades and Université Paris V, France
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75
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Abstract
Shc is a prototype adapter protein that is expressed from the earliest stages of T-cell development. Shc becomes rapidly tyrosine phosphorylated after T-cell receptor (TCR) engagement. Expression of dominant negative forms of Shc in T-cell lines had also suggested a role for this adapter downstream of the TCR. However, until recently, the relative significance of Shc compared to several other adapters in T cells was unclear. Mice lacking Shc expression specifically in the T-cell lineage together with inducible expression of dominant negative Shc in transgenic mice have revealed an essential and nonredundant role for Shc in thymic T-cell development. Functional defects in a Jurkat T-cell line lacking Shc expression also suggest a role for Shc in mature T-cell functions. While the requirement of Shc in T-cell signaling is now established, precisely what signaling pathways downstream of Shc make this adapter unique are less clear. Although the Shc-mediated activation of the extracellular signal regulated kinase (Erk)/mitogen-activated protein kinase (MAPK) pathway could be one component, Shc likely signals to other pathways in T cells that are not yet discovered. A better molecular understanding of Shc function in the future could provide insights into how multiple adapters coordinate the various outcomes downstream of the TCR.
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Affiliation(s)
- Li Zhang
- Department of Microbiology and the Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, VA 22908, USA
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76
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Norment AM, Bogatzki LY, Klinger M, Ojala EW, Bevan MJ, Kay RJ. Transgenic expression of RasGRP1 induces the maturation of double-negative thymocytes and enhances the production of CD8 single-positive thymocytes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:1141-9. [PMID: 12538669 DOI: 10.4049/jimmunol.170.3.1141] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
RasGRP1 is a guanine nucleotide exchange factor for Ras that is required for the efficient production of both CD4 and CD8 single-positive thymocytes. We found that RasGRP1 expression is rapidly up-regulated in double-negative thymocytes following pre-TCR ligation. Transgenic overexpression of RasGRP1 compensated for deficient pre-TCR signaling in vivo, enabling recombinase-activating gene 2(-/-) double-negative thymocytes to mature to the double-positive stage. RasGRP1 transgenic mice had a 4-fold increase in CD8 single-positive thymocytes, most of which had atypically low levels of CD3. The RasGRP1 transgene lowered the threshold of TCR signaling needed to initiate proliferation of single-positive thymocytes, with this effect being particularly evident among CD8 single-positive cells. In 3-day cultures, TCR stimulation via anti-CD3 caused a 10-fold increase in the ratio of CD8 to CD4 thymocytes among RasGRP1 transgenic vs nontransgenic thymocytes. These results demonstrate that in addition to driving the double-negative to double-positive transition, increased expression of RasGRP1 selectively increases CD8 single-positive thymocyte numbers and enhances their responsiveness to TCR signaling.
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MESH Headings
- Adjuvants, Immunologic/biosynthesis
- Adjuvants, Immunologic/genetics
- Adjuvants, Immunologic/physiology
- Amino Acid Sequence
- Animals
- CD8 Antigens/biosynthesis
- CD8 Antigens/genetics
- CD8-Positive T-Lymphocytes/cytology
- CD8-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/metabolism
- Cell Differentiation/genetics
- Cell Differentiation/immunology
- Cell Division/genetics
- Cell Division/immunology
- Crosses, Genetic
- DNA-Binding Proteins/biosynthesis
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/physiology
- Guanine Nucleotide Exchange Factors
- Humans
- Lymphocyte Count
- Mice
- Mice, Inbred C57BL
- Mice, Inbred DBA
- Mice, Knockout
- Mice, Transgenic
- Molecular Sequence Data
- Nuclear Proteins
- Receptors, Antigen, T-Cell/immunology
- Receptors, Antigen, T-Cell/metabolism
- Receptors, Antigen, T-Cell/physiology
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- T-Lymphocytes/cytology
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- Thymus Gland/cytology
- Thymus Gland/immunology
- Thymus Gland/metabolism
- Transgenes/immunology
- Up-Regulation/genetics
- Up-Regulation/immunology
- ras Proteins/physiology
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Affiliation(s)
- Anne M Norment
- Department of Immunology, University of Washington, Seattle, WA 98195, USA
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77
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Sommers CL, Samelson LE, Love PE. LAT: a T lymphocyte adapter protein that couples the antigen receptor to downstream signaling pathways. Bioessays 2003; 26:61-7. [PMID: 14696041 DOI: 10.1002/bies.10384] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Adapter molecules in a variety of signal transduction systems link receptors to a limited number of commonly used downstream signaling pathways. During T-cell development and mature T-cell effector function, a multichain receptor (the pre-T-cell antigen receptor or the T-cell antigen receptor) activates several protein tyrosine kinases. Receptor and kinase activation is linked to distal signaling pathways (PLC-gamma1 activation, Ca2+ influx, PKC activation and Ras/Erk activation) via the adapter protein LAT (Linker for Activation of T cells). Structure/function studies of LAT including expression of selected LAT point mutations in vivo reveals that these multiple pathways are integrated at the level of the LAT adapter. These studies suggest that similar levels of control may be found in other systems where adapter molecules are known to have important functions.
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Affiliation(s)
- Connie L Sommers
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4255, USA.
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78
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Schmitt TM, Zúñiga-Pflücker JC. Induction of T cell development from hematopoietic progenitor cells by delta-like-1 in vitro. Immunity 2002; 17:749-56. [PMID: 12479821 DOI: 10.1016/s1074-7613(02)00474-0] [Citation(s) in RCA: 864] [Impact Index Per Article: 39.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The molecular interactions provided by the thymic microenvironment that predicate T cell development remain obscure. Here, we show that a bone marrow stromal cell line ectopically expressing the Notch ligand Delta-like-1 loses its ability to support B cell lymphopoiesis, but acquires the capacity to induce the differentiation of hematopoietic progenitors into CD4 CD8 double- and single-positive T cells. Both gammadelta-TCR(+) and alphabeta-TCR(+) T cells are generated, and CD8(+) TCR(hi) cells produce gamma-interferon following CD3/TCR stimulation. These results establish that expression of Delta-like-1 on stromal cells provides key signals for the induction of T cell lineage commitment, stage-specific progenitor expansion, TCR gene rearrangement, and T cell differentiation in the absence of a thymus. Thus, it is likely that Delta-like-1/Notch interactions by the thymus underpin its unique ability to promote lineage commitment and differentiation of T cells.
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Affiliation(s)
- Thomas M Schmitt
- Department of Immunology, University of Toronto, Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario, Canada
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79
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Abstract
T lymphocytes originate from pluripotent precursors and undergo lasting commitment to the T cell developmental fate during their processing in the thymus. Commitment includes both the acquisition of essential T cell characteristics and the foreclosing of other developmental options. Gain of T cell characteristics is probably mediated by separate mechanisms, at least in detail, from loss of alternative developmental potentials. Programmed shifts in survival requirements make changes irreversible. Here we review the current evidence identifying the regulatory components of this commitment pathway, and the first hints of how they work together. Roles for PU.1, GATA-3, and their target genes are highlighted.
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Affiliation(s)
- Ellen V Rothenberg
- Division of Biology 156-29, California Institute of Technology, Pasadena, CA 91125, USA.
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80
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Priatel JJ, Teh SJ, Dower NA, Stone JC, Teh HS. RasGRP1 transduces low-grade TCR signals which are critical for T cell development, homeostasis, and differentiation. Immunity 2002; 17:617-27. [PMID: 12433368 DOI: 10.1016/s1074-7613(02)00451-x] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Two important Ras-guanyl nucleotide exchange factors, Sos and RasGRP1, control Ras activation in thymocytes. However, the relative contribution of these two exchange factors to Ras/ERK activation and their resulting impact on positive and negative selection is unclear. We have produced two lines of RasGRP1(-/-) TCR transgenic mice to determine the effect of RasGRP1 in T cell development under conditions of defined TCR signaling. Our results demonstrate that RasGRP1 is crucial for thymocytes expressing weakly selecting TCRs whereas those that express stronger selecting TCRs are more effective at utilizing RasGRP1-independent mechanisms for ERK activation and positive selection. Analysis of RasGRP1(-/-) peripheral T cells also revealed hitherto unidentified functions of RasGRP1 in regulating T cell homeostasis and sustaining antigen-induced developmental programming.
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Affiliation(s)
- John J Priatel
- Department of Microbiology and Immunology, University of British Columbia, Vancouver V6T 1Z3, Canada
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81
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Lin WY, Roberts MR. Developmental dissociation of T cells from B, NK, and myeloid cells revealed by MHC class II-specific chimeric immune receptors bearing TCR-zeta or FcR-gamma chain signaling domains. Blood 2002; 100:3045-8. [PMID: 12351421 DOI: 10.1182/blood-2002-02-0428] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The T-cell receptor zeta (TCR-zeta) and FcR-gamma chains play a critical role in mediating signal transduction. We have previously described HIV glycoprotein 120 (gp120)-specific chimeric immune receptors (CIRs) in which the extracellular domain of CD4 is linked to the signaling domain of zeta (CD4zeta) or gamma (CD4gamma). Such CIRs are efficiently expressed following retroviral transduction of mature T cells and specifically redirect effector functions toward HIV-infected targets. In this report, we examine development of CD4zeta- or CD4gamma-expressing T cells from retrovirally transduced hematopoietic stem cells following bone marrow transplantation. Although CD4zeta/gamma-expressing myeloid, NK, and B cells were efficiently reconstituted, parallel development of CD4zeta/gamma-expressing T cells was blocked prior to the CD25(+)CD44(+) prothymocyte stage. In contrast, T cells expressing a signaling-defective CIR were efficiently generated. When major histocompatibility complex (MHC) class II-deficient mice were used as transplant recipients, development of CD4zeta/gamma-expressing T cells was restored. We conclude that CD4zeta/gamma signaling generated following engagement of MHC class II selectively arrests T-lineage development.
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Affiliation(s)
- Wei Yu Lin
- University of Virginia, Charlottesville, VA 22908, USA
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82
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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.
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Affiliation(s)
- Alison M Michie
- Department of Immunology and Bacteriology, Western Infirmary, University of Glasgow, Glasgow, Scotland, G11 6NT, UK
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83
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Vaillant F, Blyth K, Andrew L, Neil JC, Cameron ER. Enforced expression of Runx2 perturbs T cell development at a stage coincident with beta-selection. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:2866-74. [PMID: 12218099 DOI: 10.4049/jimmunol.169.6.2866] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The development of T cells in the thymus is regulated by a series of stage-specific transcription factors. Deregulated expression of these factors can lead to alterations in thymocyte development with the production of aberrant cell subsets and predispose to tumor formation. The three genes of the Runx family are multilineage regulators of differentiation that have been reported to be expressed in the T cell lineage. However, their roles in thymocyte development and T cell function are largely unknown. While the Runx2/Cbfa1/AML3/Pebp2alphaa gene plays a primary role in osteogenesis and regulates a number of key bone regulatory genes, we show here that Runx2 is also expressed during the earliest phase of thymic development, in the double-negative subset. Furthermore, enforced expression of Runx2 in transgenic mice under the CD2 promoter was found to affect T cell development at a stage coincident with beta-selection, resulting in an expansion of double-negative CD4 and CD8 immature single-positive cells. Unlike wild-type controls this preselection population (CD4-CD8+heat-stable Ag+TCR-) is in a nonproliferative state, but appears to be primed for further transformation events. Overall the data suggest that Runx2 accelerates development to the CD8 immature single-positive stage, but retards subsequent differentiation to the double-positive stage. Thus, Runx2 joins a small group of transcription factors that can interfere with early T cell development, cause an expansion of a specific subset, and predispose to lymphoma.
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Affiliation(s)
- François Vaillant
- Molecular Oncology Laboratory, Institute of Comparative Medicine, University of Glasgow Veterinary School, Glasgow, United Kingdom.
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84
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Zhang L, Camerini V, Bender TP, Ravichandran KS. A nonredundant role for the adapter protein Shc in thymic T cell development. Nat Immunol 2002; 3:749-55. [PMID: 12101399 DOI: 10.1038/ni820] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Signaling via the pre-T cell receptor (pre-TCR) regulates survival, proliferation, allelic exclusion and differentiation of thymocytes. The role played by the adapter protein Shc in T cells has remained controversial, and its role in pre-TCR signaling has not been addressed. We examined Shc function in thymic T cell development using two genetic approaches. Cre-loxP-mediated inducible expression in transgenic mice of a phosphorylation-defective mutant of Shc impaired signaling through the pre-TCR as well as subsequent proliferation and differentiation. Conditional deletion of the Shc locus in thymocytes also affected thymic maturation at the same pre-TCR developmental stage. Thus, both Shc expression and its tyrosine phosphorylation play an essential and nonredundant role in thymic T cell development.
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Affiliation(s)
- Li Zhang
- Beirne B. Carter Center for Immunology Research and Department of Microbiology University of Virginia, Charlottesville, VA 22908, USA
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85
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Wabakken T, Hauge H, Finne EF, Wiedlocha A, Aasheim H. Expression of human protein tyrosine phosphatase epsilon in leucocytes: a potential ERK pathway-regulating phosphatase. Scand J Immunol 2002; 56:195-203. [PMID: 12121439 DOI: 10.1046/j.1365-3083.2002.01126.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The expression of protein tyrosine phosphatase epsilon (PTPepsilon) was studied in human tissues and blood cells. High mRNA expression was observed in peripheral blood leucocytes, particularly in monocytes and granulocytes which revealed at least four distinct transcripts. In lymphocytes, PTPepsilon expression was induced after 12-O-tetradecanoylphorbol-13-acetate (TPA) or antigen-receptor stimulation, indicating that PTPepsilon plays a role in the events taking place after antigen engagement. Previously, PTPepsilon has been shown to be involved in regulating voltage-gated potassium channel activity, insulin-receptor signalling and Janus kinase-signal transducers and activators of transcription (STAT) signalling. Transfection of cells with different PTPepsilon constructs and activator protein-1 reporter gene indicates that the catalytic activity of PTPepsilon is involved in the regulation of the mitogen-activated protein kinase cascade. In particular, the extracellular signal-regulated kinases (ERK1/2) were shown to be inhibited in both phosphorylation status and enzymatic activity after overexpression of PTPepsilon. Thus, PTPepsilon emerges as a phosphatase with a potential to regulate the ERK1/2 pathway either directly or indirectly through its catalytic activity.
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Affiliation(s)
- T Wabakken
- Department of Immunology, The Norwegian Radium Hospital, Oslo, Norway
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86
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Abstract
Lymphocytes arise from hematopoietic stem cells through the coordinated action of transcription factors. The E proteins (E12, E47, HEB and E2-2) have emerged as key regulators of both B and T lymphocyte differentiation. This review summarizes the current data and examines the various functions of E proteins and their antagonists, Id2 and Id3, throughout lymphoid maturation. Beyond an established role in B and T lineage commitment, E proteins continue to be essential at subsequent stages of development. E protein activity regulates the expression of surrogate and antigen receptor genes, promotes Ig and TCR rearrangements, and coordinates cell survival and proliferation with developmental progression in response to TCR signaling. Finally, this review also discusses the role of E47 as a tumor suppressor.
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Affiliation(s)
- Melanie W Quong
- Division of Biology, University of California, San Diego, 9500 Gilman Drive, MC 0366, La Jolla, California 92093-0366, USA.
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87
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Anderson MK, Hernandez-Hoyos G, Dionne CJ, Arias AM, Chen D, Rothenberg EV. Definition of regulatory network elements for T cell development by perturbation analysis with PU.1 and GATA-3. Dev Biol 2002; 246:103-21. [PMID: 12027437 DOI: 10.1006/dbio.2002.0674] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
PU.1 and GATA-3 are transcription factors that are required for development of T cell progenitors from the earliest stages. Neither one is a simple positive regulator for T lineage specification, however. When expressed at elevated levels at early stages of T cell development, each of these transcription factors blocks T cell development within a different, characteristic time window, with GATA-3 overexpression initially inhibiting at an earlier stage than PU.1. These perturbations are each associated with a distinct spectrum of changes in the regulation of genes needed for T cell development. Both transcription factors can interfere with expression of the Rag-1 and Rag-2 recombinases, while GATA-3 notably blocks PU.1 and IL-7Ralpha expression, and PU.1 reduces expression of HES-1 and c-Myb. A first-draft assembly of the regulatory targets of these two factors is presented as a provisional gene network. The target genes identified here provide insight into the basis of the effects of GATA-3 or PU.1 overexpression and into the regulatory changes that distinguish the developmental time windows for these effects.
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Affiliation(s)
- Michele K Anderson
- Division of Biology, California Institute of Technology, Pasadena 91125, USA
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88
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Rothenberg EV, Anderson MK. Elements of transcription factor network design for T-lineage specification. Dev Biol 2002; 246:29-44. [PMID: 12027432 DOI: 10.1006/dbio.2002.0667] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The complex spectrum of cell types produced in mammalian hematopoiesis can be understood as the output of highly combinatorial transcription factor action. The generation of multiple diverse combinations of transcription factors from the common starting state of the hematopoietic stem cell must be explained through the cross-regulatory interactions of these transcription factors at several levels. Here, the operation of such a network is addressed through a focus on murine T cell development, where we have recently established regulatory linkages between GATA-3 and PU.1 and multiple other factors essential to this differentiation pathway. The action of both essential/rate-limiting factors and factors with effects that shift qualitatively with dose and time of action can be traced through the regulatory interaction network. Hypothetical models are proposed to indicate the network nodes that are differentially activated in normal T cell lineage progression and in cells diverted to other potential fates.
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Affiliation(s)
- Ellen V Rothenberg
- Division of Biology 156-29, California Institute of Technology, Pasadena 91125, USA.
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89
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90
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Yeh JH, Spicuglia S, Kumar S, Sanchez-Sevilla A, Ferrier P, Imbert J. Control of IL-2Ralpha gene expression: structural changes within the proximal enhancer/core promoter during T-cell development. Nucleic Acids Res 2002; 30:1944-51. [PMID: 11972331 PMCID: PMC113837 DOI: 10.1093/nar/30.9.1944] [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: 01/11/2023] Open
Abstract
During T-cell development in thymus, CD25, the IL-2 receptor alpha chain (IL-2Ralpha) is already expressed in early double-negative (DN) thymocytes where commitment to T-cell lineage has been established, but subsequently IL-2Ralpha is dramatically down-regulated for the remainder of T-cell development. The loss of IL-2Ralpha expression after expression of the pre-TCR alpha:beta complex on the cell surface is essential for the later specific responses of mature T cells. Using appropriate mouse models and DMS genomic footprinting, we showed that the TATA box in the core promoter region of the murine IL-2Ralpha locus was occupied only in DN CD25+ T cells. Further, by chromatin immunoprecipitation assays, we evidenced that down-regulation of IL-2Ralpha transcription correlated with (i) loss of the basal transcriptional machinery; (ii) dissociation of histone acetylase p300 and BRG1, a member of the ATP-dependent chromatin remodeling complex SWI/SNF; and (iii) histone N-termini dephosphorylation plus deacetylation. In contrast, occupancy of the proximal enhancer region (positive regulatory region I) was not detected by in vivo genomic footprinting though constitutive accessibility of the promoter region for DNase I digestion both in the DN and double-positive stages correlated with the constitutive association of CBP and PCAF to the IL-2Ralpha core promoter. These results exemplify one mechanism by which a promoter enables transcription to switch on and off during T-cell differentiation.
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Affiliation(s)
- Jung-Hua Yeh
- INSERM U119-IFR57, 27 boulevard Lei Roure, 13009 Marseille, France
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91
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Carleton M, Haks MC, Smeele SAA, Jones A, Belkowski SM, Berger MA, Linsley P, Kruisbeek AM, Wiest DL. Early growth response transcription factors are required for development of CD4(-)CD8(-) thymocytes to the CD4(+)CD8(+) stage. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:1649-58. [PMID: 11823493 DOI: 10.4049/jimmunol.168.4.1649] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Progression of immature CD4(-)CD8(-) thymocytes beyond the beta-selection checkpoint to the CD4(+)CD8(+) stage requires activation of the pre-TCR complex; however, few of the DNA-binding proteins that serve as molecular effectors of those pre-TCR signals have been identified. We demonstrate in this study that members of the early growth response (Egr) family of transcription factors are critical effectors of the signals that promote this developmental transition. Specifically, the induction of three Egr family members (Egr1, 2, and 3) correlates with pre-TCR activation and development of CD4(-)CD8(-) thymocytes beyond the beta-selection checkpoint. Enforced expression of each of these Egr factors is able to bypass the block in thymocyte development associated with defective pre-TCR function. However, Egr family members may play somewhat distinct roles in promoting thymocyte development, because there are differences in the genes modulated by enforced expression of particular Egr factors. Finally, interfering with Egr function using dominant-negative proteins disrupts thymocyte development from the CD4(-)CD8(-) to the CD4(+)CD8(+) stage. Taken together, these data demonstrate that the Egr proteins play an essential role in executing the differentiation program initiated by pre-TCR signaling.
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Affiliation(s)
- Michael Carleton
- Immunobiology Working Group, Division of Basic Sciences, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
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92
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Spain LM, Liu P. TCRbeta transmembrane tyrosines are required for pre-TCR function. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:127-33. [PMID: 11751955 DOI: 10.4049/jimmunol.168.1.127] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The pre-TCR promotes thymocyte development in the alphabeta lineage. Productive rearrangement of the TCRbeta locus triggers the assembly of the pre-TCR, which includes the pTalpha chain and CD3 epsilongammadeltazeta subunits. This complex receptor signals the up-regulation of CD4 and CD8 expression, thymocyte proliferation/survival, and the cessation of TCRbeta rearrangements (allelic exclusion). In this study, we investigate the function of two conserved tyrosine residues located in the TCRbeta chain transmembrane region of the pre-TCR. We show that replacement of both tyrosines with alanine and expression of the mutant receptor in RAG-1(null) thymocytes prevents surface expression and abolishes pre-TCR function relative to wild-type receptor. Replacement of both tyrosines with phenylalanines (YF double mutant) generates a complex phenotype in which thymocyte survival and proliferation are severely disrupted, differentiation is moderately disrupted, and allelic exclusion is unaffected. We further show that the YF double mutant receptor is expressed on the cell surface and associates with pTalpha and CD3epsilon at the same level as does wild-type TCRbeta, while association of the YF double mutant with CD3zeta is slightly reduced relative to wild type. These data demonstrate that pre-TCR signaling pathways leading to proliferation and survival, differentiation, and allelic exclusion are differently sensitive to subtle mutation-induced alterations in pre-TCR structure.
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MESH Headings
- Amino Acid Sequence
- Animals
- Cell Differentiation
- Cell Survival
- Flow Cytometry
- Genes, RAG-1
- Genes, T-Cell Receptor beta
- Humans
- Lymphocyte Activation
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, SCID
- Molecular Sequence Data
- Mutation
- Protein Structure, Tertiary
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/physiology
- Sequence Homology, Amino Acid
- T-Lymphocytes/immunology
- Thymus Gland/immunology
- Tyrosine/physiology
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Affiliation(s)
- Lisa M Spain
- Jerome H. Holland Laboratory for Biomedical Research, American Red Cross, 15601 Crabbs Branch Way, Rockville, MD 20855, USA.
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93
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Kim D, Xu M, Nie L, Peng XC, Jimi E, Voll RE, Nguyen T, Ghosh S, Sun XH. Helix-loop-helix proteins regulate pre-TCR and TCR signaling through modulation of Rel/NF-kappaB activities. Immunity 2002; 16:9-21. [PMID: 11825562 DOI: 10.1016/s1074-7613(02)00264-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
E2A and HEB are basic helix-loop-helix transcription factors essential for T cell development. Complete inhibition of their activities through transgenic overexpression of their inhibitors Id1 and Tal1 leads to a dramatic loss of thymocytes. Here, we suggest that bHLH proteins play important roles in establishing thresholds for pre-TCR and TCR signaling. Inhibition of their function allows double-negative cells to differentiate without a functional pre-TCR, while anti-CD3 stimulation downregulates bHLH activities. We also find that the transcription factor NF-kappaB becomes activated in transgenic thymocytes. Further activation of NF-kappaB exacerbates the loss of thymocytes, whereas inhibition of NF-kappaB leads to the rescue of double-positive thymocytes. Therefore, we propose that E2A and HEB negatively regulate pre-TCR and TCR signaling and their removal causes hyperactivation and apoptosis of thymocytes.
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Affiliation(s)
- Dongsoo Kim
- Immunobiology and Cancer Program, Oklahoma Medical Research Foundation, 825 NE 13th Street, Oklahoma City, OK 73104, USA
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94
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Ramiro AR, Navarro MN, Carreira A, Carrasco YR, de Yébenes VG, Carrillo G, San Millán JL, Rubin B, Toribio ML. Differential developmental regulation and functional effects on pre-TCR surface expression of human pTalpha(a) and pTalpha(b) spliced isoforms. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:5106-14. [PMID: 11673521 DOI: 10.4049/jimmunol.167.9.5106] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Functional rearrangement at the TCRbeta locus leads to surface expression on developing pre-T cells of a pre-TCR complex composed of the TCRbeta-chain paired with the invariant pre-TCRalpha (pTalpha) chain and associated with CD3 components. Pre-TCR signaling triggers the expansion and further differentiation of pre-T cells into TCRalphabeta mature T cells, a process known as beta selection. Besides the conventional pTalpha transcript (termed pTalpha(a)), a second, alternative spliced, isoform of the pTalpha gene (pTalpha(b)) has been described, whose developmental relevance remains unknown. In this study, phenotypic, biochemical, and functional evidence is provided that only pTalpha(a) is capable of inducing surface expression of a CD3-associated pre-TCR complex, which seems spontaneously recruited into lipid rafts, while pTalpha(b) pairs with and retains TCRbeta intracellularly. In addition, by using real-time quantitative RT-PCR approaches, we show that expression of pTalpha(a) and pTalpha(b) mRNA spliced products is differentially regulated along human intrathymic development, so that pTalpha(b) transcriptional onset is developmentally delayed, but beta selection results in simultaneous shutdown of both isoforms, with a relative increase of pTalpha(b) transcripts in beta-selected vs nonselected pre-T cells in vivo. Relative increase of pTalpha(b) is also shown to occur upon pre-T cell activation in vitro. Taken together, our data illustrate that transcriptional regulation of pTalpha limits developmental expression of human pre-TCR to intrathymic stages surrounding beta selection, and are compatible with a role for pTalpha(b) in forming an intracellular TCRbeta-pTalpha(b) complex that may be responsible for limiting surface expression of a pTalpha(a)-containing pre-TCR and/or may be competent to signal from a subcellular compartment.
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MESH Headings
- Antigens, CD/biosynthesis
- Antigens, Differentiation, T-Lymphocyte/biosynthesis
- CD3 Complex/biosynthesis
- Cell Line
- Gene Expression Regulation, Developmental
- Genes, T-Cell Receptor alpha
- Genes, T-Cell Receptor beta
- Humans
- Lectins, C-Type
- Protein Isoforms
- Protein Precursors/biosynthesis
- RNA Splicing
- Receptors, Antigen, T-Cell, alpha-beta/biosynthesis
- Thymus Gland/metabolism
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Affiliation(s)
- A R Ramiro
- Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain
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95
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Koretzky GA, Myung PS. Positive and negative regulation of T-cell activation by adaptor proteins. Nat Rev Immunol 2001; 1:95-107. [PMID: 11905825 DOI: 10.1038/35100523] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Adaptor proteins, molecules that mediate intermolecular interactions, are now known to be as crucial for lymphocyte activation as are receptors and effectors. Extensive work from numerous laboratories has identified and characterized many of these adaptors, demonstrating their roles as both positive and negative regulators. Studies into the molecular basis for the actions of these molecules shows that they function in various ways, including: recruitment of positive or negative regulators into signalling networks, modulation of effector function by allosteric regulation of enzymatic activity, and by targeting other proteins for degradation. This review will focus on a number of adaptors that are important for lymphocyte function and emphasize the various ways in which these proteins carry out their essential roles.
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Affiliation(s)
- G A Koretzky
- Abramson Family Cancer Research Institute and Department of Pathology, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
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96
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Abstract
Reciprocal interactions between bone marrow derived precursor cells and the thymic environment lead to the generation of the complete repertoire of diverse and functional T cells. We have previously shown that p38 MAP kinase is activated in response to intrathymic signals in thymocytes. In this report we provide evidence that p38 MAP kinase activity is essential for pre-TCR-mediated transition of thymocytes from the CD4- CD8- to the CD4+ CD8+ stage of development. In the absence of p38 MAP kinase activity differentiation of alpha beta T cells, but not gamma delta T cells, was blocked.
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Affiliation(s)
- T Mulroy
- Department of Pediatric Oncology, Dana Farber Cancer Institute, Boston, MA 02115, USA
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97
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Yannoutsos N, Wilson P, Yu W, Chen HT, Nussenzweig A, Petrie H, Nussenzweig MC. The role of recombination activating gene (RAG) reinduction in thymocyte development in vivo. J Exp Med 2001; 194:471-80. [PMID: 11514603 PMCID: PMC2193494 DOI: 10.1084/jem.194.4.471] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Assembly of T cell receptor (TCR)alpha/beta genes by variable/diversity/joining (V[D]J) rearrangement is an ordered process beginning with recombination activating gene (RAG) expression and TCRbeta recombination in CD4(-)CD8(-)CD25(+) thymocytes. In these cells, TCRbeta expression leads to clonal expansion, RAG downregulation, and TCRbeta allelic exclusion. At the subsequent CD4(+)CD8(+) stage, RAG expression is reinduced and V(D)J recombination is initiated at the TCRalpha locus. This second wave of RAG expression is terminated upon expression of a positively selected alpha/beta TCR. To examine the physiologic role of the second wave of RAG expression, we analyzed mice that cannot reinduce RAG expression in CD4(+)CD8(+) T cells because the transgenic locus that directs RAG1 and RAG2 expression in these mice is missing a distal regulatory element essential for reinduction. In the absence of RAG reinduction we find normal numbers of CD4(+)CD8(+) cells but a 50-70% reduction in the number of mature CD4(+)CD8(-) and CD4(-)CD8(+) thymocytes. TCRalpha rearrangement is restricted to the 5' end of the Jalpha cluster and there is little apparent secondary TCRalpha recombination. Comparison of the TCRalpha genes expressed in wild-type or mutant mice shows that 65% of all alpha/beta T cells carry receptors that are normally assembled by secondary TCRalpha rearrangement. We conclude that RAG reinduction in CD4(+)CD8(+) thymocytes is not required for initial TCRalpha recombination but is essential for secondary TCRalpha recombination and that the majority of TCRalpha chains expressed in mature T cells are products of secondary recombination.
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Affiliation(s)
- N Yannoutsos
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10021, USA.
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