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Maier H, Ostraat R, Gao H, Fields S, Shinton SA, Medina KL, Ikawa T, Murre C, Singh H, Hardy RR, Hagman J. Early B cell factor cooperates with Runx1 and mediates epigenetic changes associated with mb-1 transcription. Nat Immunol 2004; 5:1069-77. [PMID: 15361869 DOI: 10.1038/ni1119] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2004] [Accepted: 08/23/2004] [Indexed: 11/08/2022]
Abstract
Cd79a (called mb-1 here) encodes the Ig-alpha signaling component of the B cell receptor. The early B cell-specific mb-1 promoter was hypermethylated at CpG dinucleotides in hematopoietic stem cells but became progressively unmethylated as B cell development proceeded. The transcription factor Pax5 activated endogenous mb-1 transcription in a plasmacytoma cell line, but could not when the promoter was methylated. In this context, early B cell factor (EBF), a transcription factor required for B lymphopoiesis, potentiated activation of mb-1 by Pax5. EBF and the basic helix-loop-helix transcription factor E47 each contributed to epigenetic modifications of the mb-1 promoter, including CpG demethylation and nucleosomal remodeling. EBF function was enhanced by interaction with the transcription factor Runx1. These data suggest a molecular basis for the hierarchical dependence of Pax5 function on EBF and E2A in B lymphocyte development.
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77
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Abstract
It is generally assumed that once a cell commits to a certain lineage it no longer can change its fate. A new study in this issue of Cell provides compelling evidence that committed mature B lineage cells can be reprogrammed to become macrophages.
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78
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O'Neil J, Shank J, Cusson N, Murre C, Kelliher M. TAL1/SCL induces leukemia by inhibiting the transcriptional activity of E47/HEB. Cancer Cell 2004; 5:587-96. [PMID: 15193261 DOI: 10.1016/j.ccr.2004.05.023] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2003] [Revised: 03/16/2004] [Accepted: 04/12/2004] [Indexed: 11/24/2022]
Abstract
Activation of the basic-helix-loop-helix (bHLH) gene TAL1 (or SCL) is a frequent gain-of-function mutation in T cell acute lymphoblastic leukemia (T-ALL). To provide genetic evidence that tal1/scl induces leukemia by interfering with E47 and HEB, we expressed tal1/scl in an E2A or HEB heterozygous background. These mice exhibit disease acceleration and perturbed thymocyte development due to repression of E47/HEB target genes. In tal1/scl thymocytes, we find the corepressor mSin3A bound to the CD4 enhancer, whereas an E47/HEB/p300 complex is detected in wild-type thymocytes. Furthermore, tal1/scl tumors are sensitive to pharmacologic inhibition of HDAC and undergo apoptosis. These data demonstrate that tal1/scl induces leukemia by repressing E47/HEB and suggest that HDAC inhibitors may prove efficacious in T-ALL patients who express TAL1/SCL.
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79
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Wright TJ, Ladher R, McWhirter J, Murre C, Schoenwolf GC, Mansour SL. Mouse FGF15 is the ortholog of human and chick FGF19, but is not uniquely required for otic induction. Dev Biol 2004; 269:264-75. [PMID: 15081372 DOI: 10.1016/j.ydbio.2004.02.003] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2003] [Revised: 01/29/2004] [Accepted: 02/02/2004] [Indexed: 10/26/2022]
Abstract
The inner ear develops from an ectodermal placode that is specified by inductive signals from the adjacent neurectoderm and underlying mesoderm. In chick, fibroblast growth factor (Fgf)-19 is expressed in mesoderm underlying the presumptive otic placode, and human FGF19 induces expression of otic markers in a tissue explant containing neural plate and surface ectoderm. We show here that mouse Fgf15 is the sequence homolog of chick and human Fgf19/FGF19. In addition, we show that FGF15, like FGF19, is sufficient to induce expression of otic markers in a chick explant assay, suggesting that these FGFs are orthologs. Mouse embryos lacking Fgf15, however, do not have otic abnormalities at E9.5-E10.5, suggesting that Fgf15 is not uniquely required for otic induction or early patterning of the otocyst. To compare FGF15 and FGF19 signaling components and assess where signals potentially redundant with FGF15 might function, we determined the expression patterns of Fgf15 and Fgf19. Unlike Fgf19, Fgf15 is not expressed in mesoderm underlying the presumptive otic placode, but is expressed in the adjacent neurectoderm. Fgfr4, which encodes the likely receptor for both FGF19 and FGF15, is expressed in the neurectoderm of both species, and is also expressed in the mesoderm only in chick. These results suggest the hypotheses that during otic induction, FGF19 signals in either an autocrine fashion to the mesoderm or a paracrine fashion to the neurectoderm, whereas FGF15 signals in an autocrine fashion to the neurectoderm. Thus, the FGFs that signal to the neurectoderm are the best potential candidates for redundancy with FGF15 during mouse otic development.
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80
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Quong MW, Martensson A, Langerak AW, Rivera RR, Nemazee D, Murre C. Receptor editing and marginal zone B cell development are regulated by the helix-loop-helix protein, E2A. ACTA ACUST UNITED AC 2004; 199:1101-12. [PMID: 15078898 PMCID: PMC2211894 DOI: 10.1084/jem.20031180] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Previous studies have indicated that the E2A gene products are required to initiate B lineage development. Here, we demonstrate that E2A+/− B cells that express an autoreactive B cell receptor fail to mature due in part to an inability to activate secondary immunoglobulin (Ig) light chain gene rearrangement. Both RAG1/2 gene expression and RS deletion are severely defective in E2A+/− mice. Additionally, we demonstrate that E2A+/− mice show an increase in the proportion of marginal zone B cells with a concomitant decrease in the proportion of follicular B cells. In contrast, Id3-deficient splenocytes show a decline in the proportion of marginal zone B cells. Based on these observations, we propose that E-protein activity regulates secondary Ig gene rearrangement at the immature B cell stage and contributes to cell fate determination of marginal zone B cells. Additionally, we propose a model in which E-proteins enforce the developmental checkpoint at the immature B cell stage.
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81
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Ikawa T, Kawamoto H, Wright LYT, Murre C. Long-Term Cultured E2A-Deficient Hematopoietic Progenitor Cells Are Pluripotent. Immunity 2004; 20:349-60. [PMID: 15030778 DOI: 10.1016/s1074-7613(04)00049-4] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2003] [Revised: 01/19/2004] [Accepted: 02/11/2004] [Indexed: 11/23/2022]
Abstract
E2A proteins are essential for the development of B cells beyond the progenitor cell stage. Here we have isolated E2A-deficient bone marrow-derived cells that have the ability to grow long-term in vitro and coexpress, at low levels, regulators of different hematopoietic cell lineages. When transferred into lethally irradiated hosts, E2A-deficient hematopoietic progenitor cells reconstitute the T, NK, myeloid, dendritic, and erythroid lineages but fail to develop into mature B lineage cells. Enforced expression of E47 in E2A-deficient hematopoietic progenitor cells directly activates the transcription of a subset of B lineage-specific genes, including lambda5, mb-1, and Pax5. In contrast, E47 inhibits the expression of regulators of other hematopoietic lineages, including TCF-1 and GATA-1. These observations indicate that E2A-deficient hematopoietic progenitor cells remain pluripotent after long-term culture in vitro and that E2A proteins play a critical role in B cell commitment.
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82
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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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83
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Murre C. Regulating intertwining proteins. Mol Cell 2003; 12:1061-2. [PMID: 14636564 DOI: 10.1016/s1097-2765(03)00449-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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84
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Abstract
Basic helix-loop-helix (bHLH) transcription factors are important regulators of lineage determination during embryogenesis. Initial experiments in Drosophila showed that early neural selection and specification are dependent on atonal (ato) and members of the achaete-scute complex (as-c). In mammals, transcription factors homologous to as-c and ato are causally involved during development of organs throughout the body. Development of subsets of lineages in intestine, stomach, pancreas, lung, thyroid and placenta have been shown to be regulated by members of the as-c and ato families. These functional studies show that an individual bHLH transcription factor can regulate multiple developmental processes throughout the mammalian body, which implicates that extant as-c and ato transcription factors play a distinct function dependent on their cellular context. Based on the synergistic activation of the insulin, POMC and Pax4 promotors by bHLH and homeobox (Hox) protein complexes, we hypothesize that the underlying cellular function-modulating factors include members of the Hox and paired box (Pax) multigene families. These examples indicate that unique combinations of bHLH and Hox proteins, mediated by protein-protein interactions, might be responsible for activating cell-specific sets of target genes.
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85
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Sayegh CE, Quong MW, Agata Y, Murre C. E-proteins directly regulate expression of activation-induced deaminase in mature B cells. Nat Immunol 2003; 4:586-93. [PMID: 12717431 DOI: 10.1038/ni923] [Citation(s) in RCA: 195] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2003] [Accepted: 03/11/2003] [Indexed: 11/09/2022]
Abstract
Activated mature B cells in which the DNA-binding activity of E-proteins has been disrupted fail to undergo class switch recombination. Here we show that activated B cells overexpressing the antagonist helix-loop-helix protein Id3 do not induce expression of the murine Aicda gene encoding activation-induced deaminase (AID). A highly conserved intronic regulatory element in Aicda binds E-proteins both in vitro and in vivo. The transcriptional activity of this element is regulated by E-proteins. We show that the enforced expression of AID in cells overexpressing Id3 partially restores class switch recombination. Taken together, our observations link helix-loop-helix activity and Aicda gene expression in a common pathway, in which E-protein activity is required for the efficient induction of Aicda transcription.
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86
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Engel I, Murre C. Disruption of pre-TCR expression accelerates lymphomagenesis in E2A-deficient mice. Proc Natl Acad Sci U S A 2002; 99:11322-7. [PMID: 12172006 PMCID: PMC123255 DOI: 10.1073/pnas.162373999] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The helix-loop-helix proteins E47 and E12, which are encoded by the E2A gene, regulate several stages of T cell development. In addition, mice deficient for E2A are highly susceptible to thymic lymphoma. Here we report that the development of lymphoma in E2A-deficient mice did not require pre- and recombinase-activating gene expression. Rather, we found that, whereas illegitimate DNA rearrangement did not play a major role in the development of these lymphomas, defects that prevented pre-T cell antigen receptor expression tended to accelerate lymphomagenesis in E2A-deficient mice. These data and previous observations also provide insight into the role of Notch in lymphoma development. Specifically, we propose that Notch activation indirectly modulates E2A activity through induction of pre-Talpha expression, ultimately leading to the development of lymphoma.
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MESH Headings
- Animals
- Basic Helix-Loop-Helix Transcription Factors
- DNA-Binding Proteins/deficiency
- DNA-Binding Proteins/genetics
- Genes, T-Cell Receptor beta
- Genotype
- Homeodomain Proteins/genetics
- Homozygote
- Lymphatic Metastasis/immunology
- Lymphoma/genetics
- Lymphoma/immunology
- Mice
- Mice, Knockout
- Receptors, Antigen, T-Cell, alpha-beta/deficiency
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Thymus Neoplasms/genetics
- Thymus Neoplasms/immunology
- Transcription Factors/deficiency
- Transcription Factors/genetics
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87
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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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88
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Kee BL, Bain G, Murre C. IL-7Ralpha and E47: independent pathways required for development of multipotent lymphoid progenitors. EMBO J 2002; 21:103-13. [PMID: 11782430 PMCID: PMC125811 DOI: 10.1093/emboj/21.1.103] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Mice that lack the transcription factors encoded by the E2A gene or the receptor for interleukin 7 (IL-7R) have severe overlapping defects in lymphocyte development. Here, we show that E2A proteins are required for the survival of early T-lineage cells; however, they function through a pathway that is distinct from the survival pathway initiated by IL-7R signaling. While E2A proteins are required to suppress caspase 3 activation, ectopic expression of the anti-apoptotic protein Bcl-2 is not sufficient to overcome the lymphopoietic defects observed in the absence of E2A. Remarkably, mice that lack both IL-7Ralpha and E47 display a synergistic decrease in the number of T-cell, NK-cell and multipotent progenitors in the thymus, indicating that these distinct survival pathways converge to promote the development of multipotent lymphoid progenitors.
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MESH Headings
- Animals
- Apoptosis
- B-Lymphocytes/cytology
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- DNA-Binding Proteins/deficiency
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Genes, bcl-2
- Hematopoiesis
- Hematopoietic Stem Cells/cytology
- Hematopoietic Stem Cells/immunology
- Hematopoietic Stem Cells/metabolism
- Killer Cells, Natural/cytology
- Killer Cells, Natural/immunology
- Killer Cells, Natural/metabolism
- Lymphocyte Count
- Lymphocytes/cytology
- Lymphocytes/immunology
- Lymphocytes/metabolism
- Mice
- Mice, Knockout
- Mice, Transgenic
- Models, Biological
- Receptors, Interleukin-7/deficiency
- Receptors, Interleukin-7/genetics
- Receptors, Interleukin-7/metabolism
- Signal Transduction
- T-Lymphocytes/cytology
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- TCF Transcription Factors
- Transcription Factor 7-Like 1 Protein
- Transcription Factors
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89
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Abstract
Helix-loop-helix (HLH) proteins are essential factors for lymphocyte development and function. One class of HLH proteins, the E-proteins, regulate many aspects of lymphocyte maturation, survival, proliferation, and differentiation. E-proteins are negatively regulated by another class of HLH proteins known as the Id proteins. The Id proteins function as dominant negative inhibitors of E-proteins by inhibiting their ability to bind DNA. Here we discuss the function and regulation of the Id proteins in lymphocyte development.
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90
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Abstract
Helix-loop-helix proteins are essential factors for lymphocyte development and function. In particular, E-proteins are crucial for commitment of lymphoid progenitors to the B- and T-cell lineages. E-proteins are negatively regulated by the Id class of helix-loop-helix proteins. The Id proteins function as dominant-negative inhibitors of E-proteins by inhibiting their ability to bind DNA. Here, we review the role of E-proteins and their Id protein antagonists in lymphocyte proliferation and developmental progression. In addition, we discuss how E-protein activity and Id gene expression are regulated by T-cell receptor (TCR) and pre-TCR-mediated signalling.
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91
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Engel I, Johns C, Bain G, Rivera RR, Murre C. Early thymocyte development is regulated by modulation of E2A protein activity. J Exp Med 2001; 194:733-45. [PMID: 11560990 PMCID: PMC2195962 DOI: 10.1084/jem.194.6.733] [Citation(s) in RCA: 154] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The E2A gene encodes the E47 and E12 basic helix-loop-helix (bHLH) transcription factors. T cell development in E2A-deficient mice is partially arrested before lineage commitment. Here we demonstrate that E47 expression becomes uniformly high at the point at which thymocytes begin to commit towards the T cell lineage. E47 protein levels remain high until the double positive developmental stage, at which point they drop to relatively moderate levels, and are further downregulated upon transition to the single positive stage. However, stimuli that mimic pre-T cell receptor (TCR) signaling in committed T cell precursors inhibit E47 DNA-binding activity and induce the bHLH inhibitor Id3 through a mitogen-activated protein kinase kinase-dependent pathway. Consistent with these observations, a deficiency in E2A proteins completely abrogates the developmental block observed in mice with defects in TCR rearrangement. Thus E2A proteins are necessary for both initiating T cell differentiation and inhibiting development in the absence of pre-TCR expression. Mechanistically, these data link pre-TCR mediated signaling and E2A downstream target genes into a common pathway.
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92
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93
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Goebel P, Janney N, Valenzuela JR, Romanow WJ, Murre C, Feeney AJ. Localized gene-specific induction of accessibility to V(D)J recombination induced by E2A and early B cell factor in nonlymphoid cells. J Exp Med 2001; 194:645-56. [PMID: 11535632 PMCID: PMC2195934 DOI: 10.1084/jem.194.5.645] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Accessibility of immunoglobulin (Ig) gene segments to V(D)J recombination is highly regulated and is normally only achieved in B cell precursors. We previously showed that ectopic expression of E2A or early B cell factor (EBF) with recombination activating gene (RAG) induces rearrangement of IgH and IgL genes in nonlymphoid cells. VkappaI genes throughout the locus were induced to rearrange after transfection with E2A, suggesting that the entire Vkappa locus was accessible. However, here we show that Ig loci are not opened globally but that recombination is localized. Gene families are interspersed in the D(H), Vkappa, and Vlambda loci, and we show that certain families and individual genes undergo high levels of recombination after ectopic expression of E2A or EBF, while other families within the same locus are not induced to rearrange. Furthermore, in some families, induction of germline transcription correlates with the level of induced recombination, while in others there is no correlation, suggesting that recombination is not simply initiated by induction of germline transcription. The induced repertoire seen at 24 hours does not change significantly over time indicating the absence of many secondary rearrangements and also suggesting a direct targeting mechanism. We propose that accessibility occurs in a local manner, and that binding sites for factors facilitating accessibility are therefore likely to be associated with individual gene segments.
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94
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Murre C. Role of helix-loop-helix proteins in lymphocyte development. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2001; 64:39-44. [PMID: 11232313 DOI: 10.1101/sqb.1999.64.39] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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95
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Abstract
The past year has provided insight into the mechanisms by which multipotent progenitors commit to differentiation through the B lymphocyte lineage. Mice lacking the Pax5 gene develop pro-B lymphocytes but these cells are not uniquely committed to the B lineage as they can give rise to all hematopoietic cell types if cultured under appropriate conditions. Regulators of lymphocyte proliferation and survival have also been identified that may allow lymphocytes to respond to information provided by the external environment.
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96
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Ghosh JK, Romanow WJ, Murre C. Induction of a diverse T cell receptor gamma/delta repertoire by the helix-loop-helix proteins E2A and HEB in nonlymphoid cells. J Exp Med 2001; 193:769-76. [PMID: 11257142 PMCID: PMC2193417 DOI: 10.1084/jem.193.6.769] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
During specific stages of thymocyte development, the T cell receptor (TCR) locus is assembled from variable (V), diversity (D), and joining (J) gene segments. Proper TCR gamma and delta V(D)J rearrangement during thymocyte development requires the presence of the E2A proteins. Here we show that E2A and a closely related protein, HEB, in the presence of recombination activating gene (RAG)1 and RAG2, each have the ability to activate TCR gamma and delta rearrangement in human kidney cells. The coding joints are diverse, contain nucleotide deletions, and occasionally show the presence of P nucleotides. Interestingly, only a subset of V, D, and J segments are targeted by the E2A and HEB proteins. Thus, E2A and HEB permit localized accessibility of the TCR gamma and delta loci to the recombination machinery. These data indicate that a distinct but diverse TCR repertoire can be induced in nonlymphoid cells by the mere presence of the V(D)J recombinase and the transcriptional regulators, E2A and HEB.
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97
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Kee BL, Rivera RR, Murre C. Id3 inhibits B lymphocyte progenitor growth and survival in response to TGF-beta. Nat Immunol 2001; 2:242-7. [PMID: 11224524 DOI: 10.1038/85303] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
E proteins function in many developmental processes and are essential for the formation of lymphocyte progenitors. However, it is not known whether E proteins regulate lymphocyte survival, proliferation or differentiation or how their activity is regulated during lymphocyte development. We show here a role for Id3, an inhibitor of E protein activity, in the induction of apoptosis and growth arrest. Id3 is induced in response to transforming growth factor beta (TGF-beta), a pleiotropic cytokine that inhibits the growth and survival of normal and transformed lymphocyte progenitors. In the absence of Id3, the response of lymphocyte progenitors to TGF-beta is perturbed, which indicates that Id3 is a mediator of this response. Our data show a key role for E proteins in lymphocyte survival and link the activity of E proteins, and their antagonists, to members of the TGF-beta family of cytokines.
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98
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Bain G, Cravatt CB, Loomans C, Alberola-Ila J, Hedrick SM, Murre C. Regulation of the helix-loop-helix proteins, E2A and Id3, by the Ras-ERK MAPK cascade. Nat Immunol 2001; 2:165-71. [PMID: 11175815 DOI: 10.1038/84273] [Citation(s) in RCA: 225] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Activation of mitogen-activated protein kinase (MAPK) pathways leads to cellular differentiation and/or proliferation in a wide variety of cell types, including developing thymocytes. The basic helix-loop-helix (bHLH) proteins E12 and E47 and an inhibitor HLH protein, Id3, play key roles in thymocyte differentiation. We show here that E2A DNA binding is lowered in primary immature thymocytes consequent to T cell receptor (TCR)-mediated ligation. Whereas expression of E2A mRNA and protein are unaltered, Id3 transcripts are rapidly induced upon signaling from the TCR. Activation of Id3 transcription is regulated in a dose-dependent manner by the extracellular signal-regulated kinase (ERK) MAPK module. These observations directly connect the ERK MAPK cascade and HLH proteins in a linear pathway.
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99
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100
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Planells-Cases R, Caprini M, Zhang J, Rockenstein EM, Rivera RR, Murre C, Masliah E, Montal M. Neuronal death and perinatal lethality in voltage-gated sodium channel alpha(II)-deficient mice. Biophys J 2000; 78:2878-91. [PMID: 10827969 PMCID: PMC1300874 DOI: 10.1016/s0006-3495(00)76829-9] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Neural activity is crucial for cell survival and fine patterning of neuronal connectivity during neurodevelopment. To investigate the role in vivo of sodium channels (NaCh) in these processes, we generated knockout mice deficient in brain NaChalpha(II). NaChalpha(II)(-/-) mice were morphologically and organogenically indistinguishable from their NaChalpha(+/-) littermates. Notwithstanding, NaChalpha(II)(-/-) mice died perinatally with severe hypoxia and massive neuronal apoptosis, notably in the brainstem. Sodium channel currents recorded from cultured neurons of NaChalpha(II)(-/-) mice were sharply attenuated. Death appears to arise from severe hypoxia consequent to the brainstem deficiency of NaChalpha(II). NaChalpha(II) expression is, therefore, redundant for embryonic development but essential for postnatal survival.
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