scholarly journals Induction of Early B Cell Factor (EBF) and Multiple B Lineage Genes by the Basic Helix-Loop-Helix Transcription Factor E12

1998 ◽  
Vol 188 (4) ◽  
pp. 699-713 ◽  
Author(s):  
Barbara L. Kee ◽  
Cornelis Murre
Keyword(s):  
Transcription Factors ◽  
B Cell ◽  
B Lymphocytes ◽  
Ectopic Expression ◽  
Helix Loop Helix ◽  
Rag 1 ◽  
B Lineage ◽  
Early B Cell Factor ◽  
Mitogen Activation

The transcription factors encoded by the E2A and early B cell factor (EBF) genes are required for the proper development of B lymphocytes. However, the absence of B lineage cells in E2A- and EBF-deficient mice has made it difficult to determine the function or relationship between these proteins. We report the identification of a novel model system in which the role of E2A and EBF in the regulation of multiple B lineage traits can be studied. We found that the conversion of 70Z/3 pre-B lymphocytes to cells with a macrophage-like phenotype is associated with the loss of E2A and EBF. Moreover, we show that ectopic expression of the E2A protein E12 in this macrophage line results in the induction of many B lineage genes, including EBF, IL7Rα, λ5, and Rag-1, and the ability to induce κ light chain in response to mitogen. Activation of EBF may be one of the critical functions of E12 in regulating the B lineage phenotype since expression of EBF alone leads to the activation of a subset of E12-inducible traits. Our data demonstrate that, in the context of this macrophage line, E12 induces expression of EBF and together these transcription factors coordinately regulate numerous B lineage–associated genes.

scholarly journals Early B Cell Factor Promotes B Lymphopoiesis with Reduced Interleukin 7 Responsiveness in the Absence of E2A

2004 ◽  
Vol 199 (12) ◽  
pp. 1689-1700 ◽  
Author(s):  
Christopher S. Seet ◽  
Rachel L. Brumbaugh ◽  
Barbara L. Kee
Keyword(s):  
Transcription Factors ◽  
B Cell ◽  
B Lymphopoiesis ◽  
Protein Activity ◽  
E Proteins ◽  
Helix Loop Helix ◽  
Interleukin 7 ◽  
E Protein ◽  
B Lineage ◽  
Early B Cell Factor

The basic helix-loop-helix transcription factors encoded by the E2A gene function at the apex of a transcriptional hierarchy involving E2A, early B cell factor (EBF), and Pax5, which is essential for B lymphopoiesis. In committed B lineage progenitors, E2A proteins have also been shown to regulate many lineage-associated genes. Herein, we demonstrate that the block in B lymphopoiesis imposed by the absence of E2A can be overcome by expression of EBF, but not Pax5, indicating that EBF is the essential target of E2A required for development of B lineage progenitors. Our data demonstrate that EBF, in synergy with low levels of alternative E2A-related proteins (E proteins), is sufficient to promote expression of most B lineage genes. Remarkably, however, we find that E2A proteins are required for interleukin 7–dependent proliferation due, in part, to a role for E2A in optimal expression of N-myc. Therefore, high levels of E protein activity are essential for the activation of EBF and N-myc, whereas lower levels of E protein activity, in synergy with other B lineage transcription factors, are sufficient for expression of most B lineage genes.

Regulation of Transcription Factors Foxp1, E2A and Egr-1 By microRNA-191 Constrains B Lymphocyte Development and Suppresses Development of Diffuse Large B Cell Lymphoma

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 287-287
Author(s):  
Marcin Lyszkiewicz ◽  
Jonas Blume ◽  
Natalia Zietara ◽  
Katrin Witzlau ◽  
Jacek Puchalka ◽  
...  
Keyword(s):  
Transcription Factors ◽  
B Cell ◽  
Cell Lymphoma ◽  
Ectopic Expression ◽  
B Cell Lymphoma ◽  
Cell Development ◽  
B Cell Development ◽  
Large B Cell Lymphoma ◽  
B Lineage ◽  
Large B Cell

Abstract Development of B-cells in the bone marrow is a tightly controlled, multi-step process. Whereas its major transcriptional regulators are well characterized, less is known about its post-transcriptional regulation. It has been demonstrated that B cell development critically depends on microRNAs. Yet, the role of individual members still remains to be uncovered. Relatively subtle regulatory effects of miRNAs are well-visible in the pathways which require tight control. Disruption of such a pathway, where the protein function (i.e. transcription factor) highly depends on the gene dosage, is major cause of malignant transformation. We identified transcription factors Foxp1, E2A and Egr1 as direct targets of microRNA miR-191. Reduced expression of these transcription factors through ectopic expression of miR-191 in B-cell progenitors resulted in numerous secondary effects, such as downregulation of Rag1, Rag2, Dntt and Il7r alpha genes. In consequence, we observed impaired immunoglobulin heavy chain rearrangement and limited responsiveness to IL-7 of B cell progenitors resulting in partial developmental arrest and predisposition of immature B-cells to death during negative selection. Finally, we showed that co-overexpression of E2A or FoxP1 and miR-191 restored normal B cell development, supporting the hypothesis that both transcription factors are functionally relevant targets of miR-191. Having established a regulatory cascade comprising miR-191 at the top of hierarchy and the transcription factors Foxp1, E2A and Egr1 as its direct targets we sought to identify a pathophysiological scenario in which this cascade might be explored therapeutically. Given that the most aggressive forms of human diffuse large B cell lymphoma (DLBCL) are FOXP1 dependent, we assessed whether miR-191 was able to limit growth of DLBCL. Of note, in vivo ectopic expression of miR-191 prevented the growth of DLBCL. Consistent with murine data, expression of the three target genes FOXP1, EGR1 and TCF3 (encoding E2A) was decreased upon miR-191 overexpression. Interestingly, treatment with the histone deacetylase inhibitor vorinostat revealed decreased resistance to cell death of DLBCL lines overexpressing miR-191 in vitro. Thus, our data describe a new regulatory pathway, where miR-191 by fine-tuning key B-lineage transcription factors acts as modulator of B-cell development as well as tumor suppressor in B-lineage malignancy. Disclosures No relevant conflicts of interest to declare.

scholarly journals Overlapping Expression of Early B-Cell Factor and Basic Helix-Loop-Helix Proteins as a Mechanism To Dictate B-Lineage-Specific Activity of the λ5 Promoter

2000 ◽  
Vol 20 (10) ◽  
pp. 3640-3654 ◽  
Author(s):  
Mikael Sigvardsson
Keyword(s):  
B Cell ◽  
Specific Activity ◽  
Synergistic Activity ◽  
Mobility Shift ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Ability To Act ◽  
B Lineage ◽  
Bhlh Proteins ◽  
Early B Cell Factor

ABSTRACT The basic helix-loop-helix (bHLH) transcription factors are a large group of proteins suggested to control key events in the development of B lymphocytes as well as of other cellular lineages. To examine how bHLH proteins activate a B-lineage-specific promoter, I investigated the ability of E47, E12, Heb, E2-2, and MyoD to activate the λ5 surrogate light chain promoter. Comparison of the functional capacity of the E2A-encoded E47 and E12 proteins indicated that even though both were able to activate the λ5 promoter and act in synergy with early B-cell factor (EBF), E47 displayed a higher functional activity than E12. An ability to act in synergy with EBF was also observed for Heb, E2-2, and MyoD, suggesting that these factors were functionally redundant in this regard. Mapping of functional domains in EBF and E47 revealed that the dimerization and DNA binding domains mediated the synergistic activity. Electrophoretic mobility shift assay analysis using the 5′ part of the λ5 promoter revealed formation of template-dependent heteromeric complexes between EBF and E47, suggesting that the synergistic mechanism involves cooperative binding to DNA. These findings propose a unique molecular function for E47 and provide overlapping expression with EBF as a molecular mechanism to direct B-cell-specific target gene activation by bHLH proteins.

Differential regulation of granulopoiesis by the basic helix-loop-helix transcriptional inhibitors Id1 and Id2

Blood ◽  
2005 ◽  
Vol 105 (11) ◽  
pp. 4272-4281 ◽  
Author(s):  
Miranda Buitenhuis ◽  
Hanneke W. M. van Deutekom ◽  
Liesbeth P. Verhagen ◽  
Anders Castor ◽  
Sten Eirik W. Jacobsen ◽  
...  
Keyword(s):  
Critical Role ◽  
Ectopic Expression ◽  
Constitutive Expression ◽  
Retroviral Transduction ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Cd34 Cells ◽  
Final Maturation ◽  
Inhibitor Of Dna Binding

Abstract Inhibitor of DNA binding (Id) proteins function as inhibitors of members of the basic helix-loop-helix family of transcription factors and have been demonstrated to play an important role in regulating lymphopoiesis. However, the role of these proteins in regulation of myelopoiesis is currently unclear. In this study, we have investigated the role of Id1 and Id2 in the regulation of granulopoiesis. Id1 expression was initially up-regulated during early granulopoiesis, which was then followed by a decrease in expression during final maturation. In contrast, Id2 expression was up-regulated in terminally differentiated granulocytes. In order to determine whether Id expression plays a critical role in regulating granulopoiesis, Id1 and Id2 were ectopically expressed in CD34+ cells by retroviral transduction. Our experiments demonstrate that constitutive expression of Id1 inhibits eosinophil development, whereas in contrast neutrophil differentiation was modestly enhanced. Constitutive Id2 expression accelerates final maturation of both eosinophils and neutrophils, whereas inhibition of Id2 expression blocks differentiation of both lineages. Transplantation of β2-microglobulin-/- nonobese diabetic severe combined immunodeficient (NOD/SCID) mice with CD34+ cells ectopically expressing Id1 resulted in enhanced neutrophil development, whereas ectopic expression of Id2 induced both eosinophil and neutrophil development. These data demonstrate that both Id1 and Id2 play a critical, although differential role in granulopoiesis.

scholarly journals Early B cell factor: Regulator of B lineage specification and commitment

2008 ◽  
Vol 20 (4) ◽  
pp. 221-227 ◽  
Author(s):  
Kara Lukin ◽  
Scott Fields ◽  
Jacqueline Hartley ◽  
James Hagman
Keyword(s):  
B Cell ◽  
Lineage Specification ◽  
B Lineage ◽  
Early B Cell Factor

Fetal liver pro-B and pre-B lymphocyte clones: expression of lymphoid-specific genes, surface markers, growth requirements, colonization of the bone marrow, and generation of B lymphocytes in vivo and in vitro

1992 ◽  
Vol 12 (2) ◽  
pp. 518-530
Author(s):  
R Palacios ◽  
J Samaridis
Keyword(s):  
B Cell ◽  
B Lymphocytes ◽  
Stromal Cells ◽  
B Lymphocyte ◽  
Germ Line ◽  
Fetal Liver ◽  
Rag 1 ◽  
B Cell Precursors

We describe here the development and characterization of the FLS4.1 stromal line derived from 15-day fetal liver of BALB/c embryos and defined culture conditions that efficiently support the cloning and long-term growth of nontransformed B-220+ 14-day fetal liver cells at two stages of B-cell development, namely, pro-B lymphocytes (immunoglobulin [Ig] genes in germ line configuration) and pre-B cells (JH-rearranged genes with both light-chain Ig genes in the germ line state). All B-cell precursor clones require recombinant interleukin-7 (rIL-7) and FLS4.1 stromal cells for continuous growth in culture, but pro-B lymphocyte clones can also proliferate in rIL-3. None proliferate in rIL-1, rIL-2, rIL-4, rIL-5, rIL-6, or leukemia inhibitory factor. FLS4.1 stromal cells synthesize mRNA for Steel factor but not for IL-1 to IL-7; all pro-B and pre-B clones express c-Kit, the receptor for Steel factor, and a c-Kit-specific antibody inhibits the enhanced proliferative response of fetal liver B-220+ B-cell precursors supported by FLS4.1 stromal cells and exogenous rIL-7 but does not affect that promoted by rIL-7 alone. Northern (RNA) blot analysis of the expression of the MB-1, lambda 5, Vpre-B, c mu, RAG-1, and RAG-2 genes in pro-B and pre-B clones show that transcription of the MB-1 gene precedes IgH gene rearrangement and RNA synthesis from c mu, RAG-1, RAG-2, lambda 5, and Vpre-B genes. All clones at the pre-B-cell stage synthesize mRNA for c mu, RAG-1, and RAG-2 genes; transcription of the lambda 5 and Vpre-B genes seems to start after D-to-JH rearrangement in B-cell precursors, indicating that the proteins encoded by either gene are not required for B-cell progenitors to undergo D-to-JH gene rearrangement. These findings mark transcription of the MB-1 gene as one of the earliest molecular events in commitment to develop along the B-lymphocyte pathway. Indeed, both pro-B and pre-B clones can generate in vitro and in vivo B lymphocytes but not T lymphocytes; moreover, these clones do not express the CD3-gamma T-cell-specific gene, nor do they have rearranged gamma, delta, or beta T-cell antigen receptor genes.

scholarly journals Interleukin-13 in Combination With CD40 Ligand Potently Inhibits Apoptosis in Human B Lymphocytes: Upregulation of Bcl-xL and Mcl-1

Blood ◽  
1997 ◽  
Vol 89 (12) ◽  
pp. 4415-4424 ◽  
Author(s):  
Jon Lømo ◽  
Heidi Kiil Blomhoff ◽  
Sten Eirik Jacobsen ◽  
Stanislaw Krajewski ◽  
John C. Reed ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
B Lymphocytes ◽  
Peripheral Blood ◽  
Cell Apoptosis ◽  
Cell Types ◽  
Cd40 Ligand ◽  
Interleukin 13

Abstract Interleukin-13 (IL-13) is a novel T-cell–derived cytokine with IL-4–like effects on many cell types. In human B lymphocytes, IL-13 induces activation, stimulates proliferation in combination with anti-IgM or anti-CD40 antibodies, and directs Ig isotype switching towards IgE and IgG4 isotypes. We show here that IL-13 also regulates human B-cell apoptosis. IL-13 reduced spontaneous apoptosis of peripheral blood B cells in vitro, as shown by measurement of DNA fragmentation using the TUNEL and Nicoletti assays. The inhibition of cell death by IL-13 alone was significant but modest, but was potently enhanced in combination with CD40 ligand (CD40L), a survival stimulus for B cells by itself. Interestingly, IL-13 increased the expression of CD40 on peripheral blood B cells, providing a possible mechanism for the observed synergy. IL-13 alone was a less potent inhibitor of apoptosis than IL-4. Moreover, there was no additive effect of combining IL-4 and IL-13 at supraoptimal concentrations, which is consistent with the notion that the IL-4 and IL-13 binding sites share a common signaling subunit. The combination of IL-13 with CD40L augmented the expression of the Bcl-2 homologues Bcl-xL and Mcl-1, suggesting this as a possible intracellular mechanism of induced survival. By contrast, levels of Bcl-2, and two other Bcl-2 family members, Bax and Bak, remained unaltered. Given the importance of the CD40-CD40L interaction in B-cell responses, these results suggest a significant role of IL-13 in the regulation of B-cell apoptosis.

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