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A Screen for Gene Paralogies Delineating Evolutionary Branching Order of Early Metazoa. G3-GENES GENOMES GENETICS 2020; 10:811-826. [PMID: 31879283 PMCID: PMC7003098 DOI: 10.1534/g3.119.400951] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The evolutionary diversification of animals is one of Earth’s greatest marvels, yet its earliest steps are shrouded in mystery. Animals, the monophyletic clade known as Metazoa, evolved wildly divergent multicellular life strategies featuring ciliated sensory epithelia. In many lineages epithelial sensoria became coupled to increasingly complex nervous systems. Currently, different phylogenetic analyses of single-copy genes support mutually-exclusive possibilities that either Porifera or Ctenophora is sister to all other animals. Resolving this dilemma would advance the ecological and evolutionary understanding of the first animals and the evolution of nervous systems. Here we describe a comparative phylogenetic approach based on gene duplications. We computationally identify and analyze gene families with early metazoan duplications using an approach that mitigates apparent gene loss resulting from the miscalling of paralogs. In the transmembrane channel-like (TMC) family of mechano-transducing channels, we find ancient duplications that define separate clades for Eumetazoa (Placozoa + Cnidaria + Bilateria) vs. Ctenophora, and one duplication that is shared only by Eumetazoa and Porifera. In the Max-like protein X (MLX and MLXIP) family of bHLH-ZIP regulators of metabolism, we find that all major lineages from Eumetazoa and Porifera (sponges) share a duplicated gene pair that is sister to the single-copy gene maintained in Ctenophora. These results suggest a new avenue for deducing deep phylogeny by choosing rather than avoiding ancient gene paralogies.
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2
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Jacqueroud L, Bouard C, Richard G, Payen L, Devouassoux-Shisheboran M, Spicer DB, Caramel J, Collin G, Puisieux A, Tissier A, Ansieau S. The Heterodimeric TWIST1-E12 Complex Drives the Oncogenic Potential of TWIST1 in Human Mammary Epithelial Cells. Neoplasia 2017; 18:317-327. [PMID: 27237323 PMCID: PMC4887617 DOI: 10.1016/j.neo.2016.03.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 03/18/2016] [Accepted: 03/28/2016] [Indexed: 11/26/2022] Open
Abstract
The TWIST1 embryonic transcription factor displays biphasic functions during the course of carcinogenesis. It facilitates the escape of cells from oncogene-induced fail-safe programs (senescence, apoptosis) and their consequent neoplastic transformation. Additionally, it promotes the epithelial-to-mesenchymal transition and the initiation of the metastatic spread of cancer cells. Interestingly, cancer cells recurrently remain dependent on TWIST1 for their survival and/or proliferation, making TWIST1 their Achilles’ heel. TWIST1 has been reported to form either homodimeric or heterodimeric complexes mainly in association with the E bHLH class I proteins. These complexes display distinct, sometimes even antagonistic, functions during development and unequal prometastatic functions in prostate cancer cells. Using a tethered dimer strategy, we successively assessed the ability of TWIST1 dimers to cooperate with an activated version of RAS in human mammary epithelial cell transformation, to provide mice with the ability to spontaneously develop breast tumors, and lastly to maintain a senescence program at a latent state in several breast cancer cell lines. We demonstrate that the TWIST1-E12 complex, unlike the homodimer, is an oncogenic form of TWIST1 in mammary epithelial cells and that efficient binding of both partners is a prerequisite for its activity. The detection of the heterodimer in human premalignant lesions by a proximity ligation assay, at a stage preceding the initiation of the metastatic cascade, is coherent with such an oncogenic function. TWIST1-E protein heterodimeric complexes may thus constitute the main active forms of TWIST1 with regard to senescence inhibition over the time course of breast tumorigenesis.
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Affiliation(s)
- Laurent Jacqueroud
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France
| | - Charlotte Bouard
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France
| | - Geoffrey Richard
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France
| | - Léa Payen
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France; Université de Lyon 1, ISPB, Lyon, France; Hospices Civils de Lyon, Lyon, France
| | - Mojgan Devouassoux-Shisheboran
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France; Université de Lyon 1, ISPB, Lyon, France; Hospices Civils de Lyon, Lyon, France; Hôpital de la Croix-Rousse, Lyon, France
| | - Douglas B Spicer
- Center for Molecular Medicine, Main Medical Center Research Institute, Scarborough, ME, USA
| | - Julie Caramel
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France; Université de Lyon 1, ISPB, Lyon, France
| | - Guillaume Collin
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France
| | - Alain Puisieux
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France; Université de Lyon 1, ISPB, Lyon, France; Institut Universitaire de France, Paris, France
| | - Agnès Tissier
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France
| | - Stéphane Ansieau
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France.
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Zwollo P. Dissecting teleost B cell differentiation using transcription factors. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2011; 35:898-905. [PMID: 21251922 PMCID: PMC3107362 DOI: 10.1016/j.dci.2011.01.009] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 01/08/2011] [Accepted: 01/11/2011] [Indexed: 05/07/2023]
Abstract
B cell developmental pathways in teleost fishes are poorly understood. In the absence of serological reagents, an alternative approach to dissecting teleost B cell development is to use transcription factors that are differentially expressed during B cell development. This review discusses the structure and function of six transcription factors that play essential roles during teleost B cell development: Ikaros, E2A, EBF, Pax5, Blimp1, and XbpI. Research on alternative splicing of both the Ikaros and Pax5 genes in rainbow trout is presented, including their functional significance. An application is discussed that should aid in elucidating teleost B cell development and activation, by using transcription factors as developmental markers in flow cytometric analysis. Possible future studies in teleost B cell development are suggested in the context of gene regulation. Lastly, broader impacts and practical applications are discussed.
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Affiliation(s)
- Patty Zwollo
- The College of William and Mary, Department of Biology, Williamsburg, VA 23187, USA.
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Bardin AJ, Perdigoto CN, Southall TD, Brand AH, Schweisguth F. Transcriptional control of stem cell maintenance in the Drosophila intestine. Development 2010; 137:705-14. [PMID: 20147375 DOI: 10.1242/dev.039404] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Adult stem cells maintain tissue homeostasis by controlling the proper balance of stem cell self-renewal and differentiation. The adult midgut of Drosophila contains multipotent intestinal stem cells (ISCs) that self-renew and produce differentiated progeny. Control of ISC identity and maintenance is poorly understood. Here we find that transcriptional repression of Notch target genes by a Hairless-Suppressor of Hairless complex is required for ISC maintenance, and identify genes of the Enhancer of split complex [E(spl)-C] as the major targets of this repression. In addition, we find that the bHLH transcription factor Daughterless is essential to maintain ISC identity and that bHLH binding sites promote ISC-specific enhancer activity. We propose that Daughterless-dependent bHLH activity is important for the ISC fate and that E(spl)-C factors inhibit this activity to promote differentiation.
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Das S, Nikolaidis N, Nei M. Genomic organization and evolution of immunoglobulin kappa gene enhancers and kappa deleting element in mammals. Mol Immunol 2009; 46:3171-7. [PMID: 19560204 PMCID: PMC2736800 DOI: 10.1016/j.molimm.2009.05.180] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Accepted: 05/30/2009] [Indexed: 11/20/2022]
Abstract
We have studied the genomic structure and evolutionary pattern of immunoglobulin kappa deleting element (KDE) and three kappa enhancers (KE5', KE3'P, and KE3'D) in eleven mammalian genomic sequences. Our results show that the relative positions and the genomic organization of the KDE and the kappa enhancers are conserved in all mammals studied and have not been affected by the local rearrangements in the immunoglobulin kappa (IGK) light chain locus over a long evolutionary time ( approximately 120 million years of mammalian evolution). Our observations suggest that the sequence motifs in these regulatory elements have been conserved by purifying selection to achieve proper regulation of the expression of the IGK light chain genes. The conservation of the three enhancers in all mammals indicates that these species may use similar mechanisms to regulate IGK gene expression. However, some activities of the IGK enhancers might have evolved in the eutherian lineage. The presence of the three IGK enhancers, KDE, and other recombining elements (REs) in all mammals (including platypus) suggest that these genomic elements were in place before the mammalian radiation.
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Affiliation(s)
- Sabyasachi Das
- Department of Pathology and Laboratory Medicine, Emory Vaccine Center, School of Medicine, Emory University, Atlanta, GA 30322, USA.
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Regulation of V(D)J recombination by E-protein transcription factors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 650:148-56. [PMID: 19731808 DOI: 10.1007/978-1-4419-0296-2_12] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Extensive study of the E-proteins E2A and HEB duringlymphocyte development has revealed various functions for these bHLH transcription factors in regulating V(D)J recombination in both B- and T-cells. The study of E-proteins in mammals began with the identification of E2A by its ability to bind immunoglobulin heavy and light chain enhancers. Subsequent analysis has identified numerous roles for E2A and HEB at the immunoglobulin and T-cell receptor loci. E-protein targets also include the rag genes and other factors critical for recombination and for regulation of the developmental windows when cells undergo recombination. E-proteins appear to be master regulators that coordinate antigen receptor gene rearrangement and expression. This chapter focuses on how E-proteins regulate V(D)J recombination by activating transcription, initiating rearrangement and driving differentiation during B- and T-cell development.
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A role for E2-2 at the DN3 stage of early thymopoiesis. Mol Immunol 2008; 45:3302-11. [PMID: 18384878 DOI: 10.1016/j.molimm.2008.02.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Revised: 02/12/2008] [Accepted: 02/13/2008] [Indexed: 11/22/2022]
Abstract
Roles for the E-proteins E2A and HEB during T lymphocyte development have been well established. Based on our previous observations of counter selection against T cells lacking E2-2, it seemed reasonable to assume that there would be a function also for E2-2 in thymocyte development. Aiming at assigning such a role for E2-2, we analyzed the expression of E2-2, E2A, HEB as well as Id mRNA during T cell development. Interestingly, whereas all three E-proteins were expressed during early thymocyte development, significant expression beyond the DP stage was detected only for E2A. Among the Id proteins, Id2 displayed a prominent expression exclusively in DN1, whereas Id3 showed some expression in DN1, followed by a down regulation and then a prominent induction, peaking in the DP stage. E2-2 was expressed during the DN stages, as well as in the DP stage, suggesting that E2-2 operates in concert with the other E-proteins during early thymocyte development. We found that E2-2 null thymocytes displayed a partial block at the DN3 stage of development, as well as a reduced expression of pre-T alpha, known to be regulated also by E2A and HEB. The fact that E2-2 deficient thymocytes develop without gross abnormalities is likely to stem from redundancy due to the co-expression of E2A and HEB.
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Frasca D, Van der Put E, Landin AM, Gong D, Riley RL, Blomberg BB. RNA Stability of the E2A-Encoded Transcription Factor E47 Is Lower in Splenic Activated B Cells from Aged Mice. THE JOURNAL OF IMMUNOLOGY 2005; 175:6633-44. [PMID: 16272318 DOI: 10.4049/jimmunol.175.10.6633] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We have demonstrated previously that DNA binding and protein expression of the E2A-encoded transcription factor E47 are lower in nuclear extracts of activated splenic B cells from old mice. In the present study, we address how E47 protein expression is regulated in aging. Results herein show that E2A mRNA levels were decreased in stimulated splenic B cells from old as compared with young mice. RNA stability assays showed that the rate of E2A mRNA decay was accelerated in stimulated splenic B cells from old mice, but E47 protein degradation rates were comparable in young vs aged B cells, indicating that the regulation of E47 expression in activated splenic B cells occurs primarily by mRNA stability. The rates of decay of other mRNAs showed that the increased mRNA degradation in aged splenic activated B cells is not a general phenomenon but restricted to a subset of mRNAs. We next investigated the signal transduction pathways controlling E2A mRNA expression and stability and found that p38 MAPK regulates E2A mRNA expression through increased mRNA stability and is down-regulated in aged activated B cells. Results show that inhibition of p38 MAPK significantly reduces E2A mRNA stability in both young and old B cells, further stressing the role of p38 MAPK in E2A RNA stabilization. These studies demonstrate that the transcription factor E2A, critical for many aspects of B cell function, is regulated by a novel mechanism in aging.
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Affiliation(s)
- Daniela Frasca
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
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Abstract
B cell genesis declines with age, but at what stage and why remains unclear. Previous studies attribute the decline in B cell production in aged mice to both environmental and cell-intrinsic defects that impact mid-to-late stream B cell precursors. However, mounting evidence suggests that the aging process may also negatively affect the earliest phases of B cell development. We review past studies on the B cells and aging question, discuss recent data suggesting that age-associated defects in B cell development reflect deficiencies in hematopoietic stem cell-proximal progenitor pools, and provide an integrative model that will hopefully facilitate further studies into this complex problem.
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Affiliation(s)
- Juli P Miller
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, 269 John Morgan Building, 36th and Hamilton Walk, Philadelphia, PA 19104, USA
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10
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Van der Put E, Frasca D, King AM, Blomberg BB, Riley RL. Decreased E47 in senescent B cell precursors is stage specific and regulated posttranslationally by protein turnover. THE JOURNAL OF IMMUNOLOGY 2004; 173:818-27. [PMID: 15240668 DOI: 10.4049/jimmunol.173.2.818] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The E2A-encoded transcription factor E47 is crucial to B lymphopoiesis. Senescent BALB/c mice ( approximately 2 years old) had reduced pre-B cells ex vivo. Pro-B/early pre-B cells from these aged mice, both ex vivo and in vitro, were deficient in E47 protein. In vitro, IL-7 expanded pro-B/early pre-B cells from young BALB/c mice expressed E47 protein that was relatively stable over a 5-h period. Cultured senescent pro-B/early pre-B cells exhibited reduced E47 protein stability with approximately 50-90% loss of E47 over the same time period. Degradation of E47 was effectively blocked by the proteasome inhibitor lactacystin as well as calpain I and II inhibitors; E2A proteins were also shown to undergo ubiquitination. Although senescent B cell precursors expressed less E47 protein, E47 mRNA levels and turnover were normal. Therefore, E47 protein levels are reduced relatively early in B lineage differentiation in senescence and the decline in E47 protein occurs via increased protein degradation by proteasome and, possibly, calpain pathways. In contrast, normal E47 protein levels were observed within the highly reduced pre-B cell pool in aged mice. This suggests that pre-B cells in senescence undergo selection based on E47 expression. Increased degradation rates and lower steady-state levels were also observed for the transcription factors Pax-5/BSAP, Bob-1, and Ikaros, but this was not a general property of all proteins in aged B cell precursors. Therefore, altered turnover of multiple, select proteins crucial to B cell development may contribute to diminished B lymphopoiesis in old age.
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Affiliation(s)
- Elaine Van der Put
- Department of Microbiology and Immunology, University of Miami School of Medicine, Miami, FL 33101, USA
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11
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Lee LTO, Tan-Un KC, Pang RTK, Lam DTW, Chow BKC. Regulation of the Human Secretin Gene Is Controlled by the Combined Effects of CpG Methylation, Sp1/Sp3 Ratio, and the E-Box Element. Mol Endocrinol 2004; 18:1740-55. [PMID: 15118068 DOI: 10.1210/me.2003-0461] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
AbstractTo unravel the mechanisms that regulate the human secretin gene expression, in this study, we have used secretin-expressing (HuTu-80 cells, human duodenal adenocarcinoma) and non-secretin-expressing [PANC-1 (human pancreatic ductile carcinoma) and HepG2 (human hepatocellular carcinoma) cells] cell models for in vitro and in vivo analyses. By transient transfection assays, within the promoter region (−11 to −341 from ATG, relative to the ATG initiation codon), we have initially identified several functional motifs including an E-box and 2 GC-boxes. Results from gel mobility shift and chromatin immunoprecipitation assays confirmed further that NeuroD, E2A, Sp1, and Sp3 bind to these E- and GC-boxes in HuTu-80 cells in vitro and in vivo, whereas only high levels of Sp3 is observed to bind the promoter in HepG2 cells. In addition, overexpression of Sp3 resulted in a dose-dependent repression of the Sp1-mediated transactivation. Collectively, these data suggest that the Sp1/Sp3 ratio is instrumental to controlling secretin gene expression in secretin-producing and non-secretin-producing cells. The functions of GC-box and Sp proteins prompted us to investigate the possible involvement of DNA methylation in regulating this gene. Consistent with this idea, we found a putative CpG island (−336 to 262 from ATG) that overlaps with the human secretin gene promoter. By methylation-specific PCR, all the CpG dinucleo-tides (26 of them) within the CpG island in HuTu-80 cells are unmethylated, whereas all these sites are methylated in PANC-1 and HepG2 cells. The expressions of secretin in PANC-1 and HepG2 cells were subsequently found to be significantly activated by a demethylation agent, 5′-Aza-2′ deoxycytidine. Taken together, our data indicate that the human secretin gene is controlled by the in vivo Sp1/Sp3 ratio and the methylation status of the promoter.
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Affiliation(s)
- Leo Tsz-On Lee
- Department of Zoology, University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
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12
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Frasca D, Van Der Put E, Riley RL, Blomberg BB. Age-related differences in the E2A-encoded transcription factor E47 in bone marrow-derived B cell precursors and in splenic B cells. Exp Gerontol 2004; 39:481-9. [PMID: 15050281 DOI: 10.1016/j.exger.2003.09.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2003] [Revised: 09/26/2003] [Accepted: 09/30/2003] [Indexed: 10/26/2022]
Abstract
We have investigated the effects of aging on the E2A-encoded transcription factor E47, a key regulator of B cell functions, in B cell precursors and in splenic B cells. Here, we show that old mice can be classified as severely depleted, moderately depleted or not depleted mice, according to the percentage of pre-B cells in their bone marrow. IL-7-expanded populations of pro-B/early pre-B cells from bone marrow of both severely depleted and moderately depleted old mice exhibit a reduced E47 DNA-binding and expression compared to young mice, and this defect in severely depleted old mice is more dramatic than that in moderately depleted old mice. However, mRNA levels were comparable, suggesting that E47 in the bone marrow is not transcriptionally regulated. In the spleen, activated B cells from both severely depleted and moderately depleted old mice show a lower E47 DNA-binding and expression than young mice. However, in contrast to precursor B cells, E47 DNA-binding and expression are similarly and only moderately reduced in both severely depleted and in moderately depleted mice. The mRNA levels were found to be decreased in stimulated splenic B cells from old as compared to young mice, suggesting that E47 mRNA in the spleen may be both transcriptionally and/or post-transcriptionally regulated.
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Affiliation(s)
- Daniela Frasca
- Department of Microbiology and Immunology, RMSB #3146A, University of Miami School of Medicine, 1600 NW 10th Ave, Miami, FL 33136, USA.
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13
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Ishii H, Sen R, Pazin MJ. Combinatorial control of DNase I-hypersensitive site formation and erasure by immunoglobulin heavy chain enhancer-binding proteins. J Biol Chem 2003; 279:7331-8. [PMID: 14660676 DOI: 10.1074/jbc.m308973200] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNase I-hypersensitive sites in cellular chromatin are usually believed to be nucleosome-free regions generated by transcription factor binding. Using a cell-free system we show that hypersensitivity does not simply correlate with the number of DNA-bound proteins. Specifically, the leucine zipper containing basic helix-loop-helix protein TFE3 was sufficient to induce a DNase I-hypersensitive site at the immunoglobulin heavy chain micro enhancer in vitro. TFE3 enhanced binding of an ETS protein PU.1 to the enhancer. However, PU.1 binding erased the DNase I-hypersensitive site without abolishing TFE3 binding. Furthermore, TFE3 binding enhanced transcription in the presence and absence of a hypersensitive site, whereas endonuclease accessibility correlated strictly with DNase I hypersensitivity. We infer that chromatin constraints for transcription and nuclease sensitivity can differ.
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Affiliation(s)
- Haruhiko Ishii
- Graduate Program in Biophysics and Structural Biology, Brandeis University, Waltham, Massachusetts 02454, USA
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Frasca D, Nguyen D, Riley RL, Blomberg BB. Decreased E12 and/or E47 transcription factor activity in the bone marrow as well as in the spleen of aged mice. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:719-26. [PMID: 12517933 DOI: 10.4049/jimmunol.170.2.719] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The E2A-encoded transcription factors E12 and E47 are key regulators of B cell functions. They bind to the E-box site, found in regulatory regions of B cell-specific genes; promote cell survival of early pre-B cells; help to initiate Ig rearrangements; and are also involved in class switch in mature B cells in the periphery. We have investigated the expression and function of E47 and E12 in IL-7-expanded pro-B/pre-B cell precursors and in unstimulated or LPS-activated splenic B cells from young and old BALB/c mice. Results show that B cell precursors from the bone marrow of old mice exhibit a reduced expression of E2A proteins and a reduced ability to bind DNA, as compared with young mice. In the spleen, E2A protein expression and DNA binding are present in unstimulated B cells from young mice and, to a significantly lesser extent, from old mice. These are both strongly induced by activation in splenic B cells from young mice but only moderately induced in old mice, indicating that aging affects the expression and activity of E2A-encoded genes and also that DNA binding correlates with the amount of protein expression. The levels of E2A DNA binding in the spleen correlate with those in the bone marrow for individual mice. In splenic mature B cells, only E47/E47 complexes bind DNA; whereas in bone marrow B cell precursors, E47/E12 complexes participate in DNA binding. Only nuclear extracts of splenic mature B cells, but both nuclear and cytoplasmic extracts of bone marrow B cell precursors, exhibit DNA binding.
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Affiliation(s)
- Daniela Frasca
- Department of Microbiology and Immunology, University of Miami School of Medicine, FL 33136, USA
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15
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Rishi V, Vinson C. Dominant-Negative Mutants of Helix-Loop-Helix Proteins: Transcriptional Inhibition. Methods Enzymol 2003; 370:454-66. [PMID: 14712667 DOI: 10.1016/s0076-6879(03)70039-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Affiliation(s)
- Vikas Rishi
- Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bldg. 37, Rm. 2D24, Bethesda, Maryland 20892, USA
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Abstract
Lymphocytes develop from hematopoietic stem cells through a series of highly regulated differentiation events in the bone marrow and thymus. A number of transcription factors are known to collaborate in controlling the timing and specificity of gene expression required for these developmental processes to occur. The basic helix-loop-helix (bHLH) proteins encoded by the E2A gene have been shown to play particularly important roles in the initiation and progression of lymphocyte differentiation. Gene targeting experiments in mice have demonstrated a requirement for E2A proteins at the onset of B lymphocyte development. More recent studies have broadened our view on the function of E2A proteins at multiple stages of lymphopoiesis and in the regulation of lymphoid-specific gene expression. Here we review the mammalian E2A proteins and the accumulated evidence demonstrating central roles for E2A throughout early B and T lymphocyte development. We also speculate on the direction of future research on the mechanisms underlying the lineage and stage-specific functions of E2A in lymphopoiesis.
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Affiliation(s)
- Stephen Greenbaum
- Department of Immunology, Box 3010, Duke University Medical Center, 328 Jones Building, Research Drive, Durham, NC 27710, USA.
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Riley RL, Knowles J, King AM. Levels of E2A protein expression in B cell precursors are stage-dependent and inhibited by stem cell factor (c-kit ligand). Exp Hematol 2002; 30:1412-8. [PMID: 12482503 DOI: 10.1016/s0301-472x(02)00953-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The E2A-encoded proteins E47 and E12 are crucial to the development of pro-B and pre-B cells. The expression of E2A protein and mRNA during early B lymphopoiesis was determined and effects of stem cell factor (SCF; Steel factor; c-kit ligand) on E2A expression were evaluated. MATERIALS AND METHODS Ex vivo murine pro-B cells and pre-B cells were isolated and in vitro B cell precursors were derived after culture of bone marrow with rmIL-7. Levels of E2A proteins were determined by Western analysis and mRNA by RT-PCR. E2A expression in vitro was also assessed in cultures supplemented with IL-7 +/- recombinant murine SCF (rmSCF), insulin-like growth factor-1 (rhIGF-1), or Flt3-ligand (rhFlt3-L). Turnover of E2A proteins was assessed following cycloheximide treatment. RESULTS Ex vivo, pro-B cells had lower E47 protein levels than did pre-B cells but had comparable E2A mRNA levels. E2A protein, but not mRNA, levels were reduced in pro-B cells upon culture in vitro with IL-7 + rmSCF. This was associated with increased turnover of E2A proteins. In contrast, culture with IL-7 + IGF-1 or Flt3-L had minimal effects on E2A protein levels. CONCLUSION Pre-B cells expressed higher levels of E2A protein than did pro-B cells and this mainly resulted from posttranscriptional regulation. Exogenous SCF inhibited E2A protein, but not mRNA, expression in cultured B cell precursors, possibly by increasing E2A protein turnover. The capacity to respond to SCF may influence the levels of E2A during B-cell development.
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Affiliation(s)
- Richard L Riley
- Department of Microbiology and Immunology, University of Miami School of Medicine, PO Box 016960 (R138), Miami, FL 33101, USA.
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18
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Liu ZM, George-Raizen JB, Li S, Meyers KC, Chang MY, Garrard WT. Chromatin structural analyses of the mouse Igkappa gene locus reveal new hypersensitive sites specifying a transcriptional silencer and enhancer. J Biol Chem 2002; 277:32640-9. [PMID: 12080064 DOI: 10.1074/jbc.m204065200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To identify new regulatory elements within the mouse Igkappa locus, we have mapped DNase I hypersensitive sites (HSs) in the chromatin of B cell lines arrested at different stages of differentiation. We have focused on two regions encompassing 50 kilobases suspected to contain new regulatory elements based on our previous high level expression results with yeast artificial chromosome-based mouse Igkappa transgenes. This approach has revealed a cluster of HSs within the 18-kilobase intervening sequence, which we cloned and sequenced in its entirety, between the Vkappa gene closest to the Jkappa region. These HSs exhibit pro/pre-B cell-specific transcriptional silencing of a Vkappa gene promoter in transient transfection assays. We also identified a plasmacytoma cell-specific HS in the far downstream region of the locus, which in analogous transient transfection assays proved to be a powerful transcriptional enhancer. Deletional analyses reveal that for each element multiple DNA segments cooperate to achieve either silencing or enhancement. The enhancer sequence is conserved in the human Igkappa gene locus, including NF-kappaB and E-box sites that are important for the activity. In summary, our results pinpoint the locations of presumptive regulatory elements for future knockout studies to define their functional roles in the native locus.
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Affiliation(s)
- Zhi-Mei Liu
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA
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19
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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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Abstract
E2A-HLF, the chimeric fusion protein resulting from the leukemogenic translocation t(17;19), appears to employ evolutionarily conserved signaling cascades for its transforming and antiapoptotic functions. These arise from both impairment of normal E2A function and activation of a survival pathway triggered through the HLF bZip DNA binding and dimerization domain. Recent reports identify wild-type E2A as a tumor suppressor in T lymphocytes. Moreover, E2A-HLF has been shown to activate SLUG, a mammalian homologue of the cell death specification protein CES-1 in Caenorhabditis elegans, which appears to regulate an evolutionarily conserved cell survival program. Recently, several key mouse models have been generated, enabling further elucidation of these pathways on a molecular genetic level in vivo. In this review, we discuss the characteristics of both components of the fusion protein with regard to their contribution to the regulation of cell fate and the oncogenic potential of E2A-HLF.
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Affiliation(s)
- M G Seidel
- Pediatric Oncology Department, Dana-Farber Cancer Institute, 44 Binney Street, M-630, Boston, Massachusetts, MA 02115, USA
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21
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Dressel U, Bailey PJ, Wang SC, Downes M, Evans RM, Muscat GE. A dynamic role for HDAC7 in MEF2-mediated muscle differentiation. J Biol Chem 2001; 276:17007-13. [PMID: 11279209 DOI: 10.1074/jbc.m101508200] [Citation(s) in RCA: 162] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The overlapping expression profile of MEF2 and the class-II histone deacetylase, HDAC7, led us to investigate the functional interaction and relationship between these regulatory proteins. HDAC7 expression inhibits the activity of MEF2 (-A, -C, and -D), and in contrast MyoD and Myogenin activities are not affected. Glutathione S-transferase pulldown and immunoprecipitation demonstrate that the repression mechanism involves direct interactions between MEF2 proteins and HDAC7 and is associated with the ability of MEF2 to interact with the N-terminal 121 amino acids of HDAC7 that encode repression domain 1. The MADS domain of MEF2 mediates the direct interaction of MEF2 with HDAC7. MEF2 inhibition by HDAC7 is dependent on the N-terminal repression domain and surprisingly does not involve the C-terminal deacetylase domain. HDAC7 interacts with CtBP and other class-I and -II HDACs suggesting that silencing of MEF2 activity involves corepressor recruitment. Furthermore, we show that induction of muscle differentiation by serum withdrawal leads to the translocation of HDAC7 from the nucleus into the cytoplasm. This work demonstrates that HDAC7 regulates the function of MEF2 proteins and suggests that this class-II HDAC regulates this important transcriptional (and pathophysiological) target in heart and muscle tissue. The nucleocytoplasmic trafficking of HDAC7 and other class-II HDACs during myogenesis provides an ideal mechanism for the regulation of HDAC targets during mammalian development and differentiation.
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Affiliation(s)
- U Dressel
- University of Queensland, Institute for Molecular Bioscience, Centre for Molecular and Cellular Biology, Ritchie Research Laboratories, B402A, St. Lucia 4072, Queensland, Australia
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Chu C, Kohtz DS. Identification of the E2A gene products as regulatory targets of the G1 cyclin-dependent kinases. J Biol Chem 2001; 276:8524-34. [PMID: 11114297 DOI: 10.1074/jbc.m008371200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The E2A gene products, E12 and E47, are multifunctional transcription factors that as homodimers regulate B cell development, growth, and survival. In this report, the E2A gene products are shown to be targets for regulation by the G1 cyclin-dependent kinases. Two novel G1 cyclin-dependent kinase sites are identified on the N-terminal domain of E12/E47. One site displays homology to a preferential D-type cyclin-dependent kinase site (serine 780) on the retinoblastoma susceptibility gene product (pRB) and, consistent with this homology, is more efficiently phosphorylated by cyclin D1-CDK4 than by the other cyclin-dependent kinases (CDK) that were tested. The second kinase site is phosphorylated by both cyclin D1-CDK4 and cyclin A/E-CDK2 complexes. Mutation studies indicated that phosphorylation of the cyclin D1-CDK4 site, or more potently, of both the cyclin D1-CDK4 and cyclin A/E-CDK2 sites, negatively regulates the growth suppressor function associated with the N-terminal domain of E12/E47. Transient expression studies showed that ectopic expression of cyclin D1 or E negatively regulates sequence-specific activation of gene transcription by E12/E47. Analysis of site mutants, however, indicated that inhibition of E12/E47 transcriptional activity did not require the N-terminal G1 cyclin-dependent kinase sites. Together, the results suggest that the growth suppressor and transcriptional activator functions of E12/E47 are targets for regulation by G1 cyclin-dependent kinases but that the mechanisms of regulation for each function are distinct.
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Affiliation(s)
- C Chu
- Department of Pathology, Mount Sinai School of Medicine, New York, New York 10029, USA
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23
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Chen SL, Dowhan DH, Hosking BM, Muscat GE. The steroid receptor coactivator, GRIP-1, is necessary for MEF-2C-dependent gene expression and skeletal muscle differentiation. Genes Dev 2000; 14:1209-28. [PMID: 10817756 PMCID: PMC316616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2000] [Accepted: 03/24/2000] [Indexed: 02/16/2023]
Abstract
Nuclear receptor-mediated activation of transcription involves coactivation by cofactors collectively denoted the steroid receptor coactivators (SRCs). The process also involves the subsequent recruitment of p300/CBP and PCAF to a complex that synergistically regulates transcription and remodels the chromatin. PCAF and p300 have also been demonstrated to function as critical coactivators for the muscle-specific basic helix-loop-helix (bHLH) protein MyoD during myogenic commitment. Skeletal muscle differentiation and the activation of muscle-specific gene expression is dependent on the concerted action of another bHLH factor, myogenin, and the MADS protein, MEF-2, which function in a cooperative manner. We examined the functional role of one SRC, GRIP-1, in muscle differentiation, an ideal paradigm for the analysis of the determinative events that govern the cell's decision to divide or differentiate. We observed that the mRNA encoding GRIP-1 is expressed in proliferating myoblasts and post-mitotic differentiated myotubes, and that protein levels increase during differentiation. Exogenous/ectopic expression studies with GRIP-1 sense and antisense vectors in myogenic C2C12 cells demonstrated that this SRC is necessary for (1) induction/activation of myogenin, MEF-2, and the crucial cell cycle regulator, p21, and (2) contractile protein expression and myotube formation. Furthermore, we demonstrate that the SRC GRIP-1 coactivates MEF-2C-mediated transcription. GRIP-1 also coactivates the synergistic transactivation of E box-dependent transcription by myogenin and MEF-2C. GST-pulldowns, mammalian two-hybrid analysis, and immunoprecipitation demonstrate that the mechanism involves direct interactions between MEF-2C and GRIP-1 and is associated with the ability of the SRC to interact with the MADS domain of MEF-2C. The HLH region of myogenin mediates the direct interaction of myogenin and GRIP-1. Interestingly, interaction with myogenic factors is mediated by two regions of GRIP-1, an amino-terminal bHLH-PAS region and the carboxy-terminal region between amino acids 1158 and 1423 (which encodes an activation domain, has HAT activity, and interacts with the coactivator-associated arginine methyltransferase). This work demonstrates that GRIP-1 potentiates skeletal muscle differentiation by acting as a critical coactivator for MEF-2C-mediated transactivation and is the first study to ascribe a function to the amino-terminal bHLH-PAS region of SRCs.
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Affiliation(s)
- S L Chen
- University of Queensland, Institute for Molecular Biosciences, Centre for Molecular and Cellular Biology, Ritchie Research Laboratories, B402A, St. Lucia, 4072, Queensland, Australia
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24
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Verastegui C, Bertolotto C, Bille K, Abbe P, Ortonne JP, Ballotti R. TFE3, a transcription factor homologous to microphthalmia, is a potential transcriptional activator of tyrosinase and TyrpI genes. Mol Endocrinol 2000; 14:449-56. [PMID: 10707962 DOI: 10.1210/mend.14.3.0428] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Microphthalmia gene encodes a basic helix-loop-helix-leucine zipper (bHLH-Zip) transcription factor involved in the development of the melanocyte lineage and plays a key role in the transcriptional regulation of the melanogenic enzymes, tyrosinase and TyrpI. Recently, we have shown that Microphthalmia mediates the melanogenic effects elicited by alphaMSH that up-regulates the expression of tyrosinase through the activation of the cAMP pathway. Therefore, Microphthalmia appears as a principal gene in melanocyte development and functioning. Among the transcription factors of the bHLH-Zip family, TFE3 and TFEB show a remarkably elevated homology with Microphthalmia. These observations prompted us to investigate the role of TFE3 and TFEB in the regulation of tyrosinase and TyrpI gene transcription. We show in this report that overexpression of TFE3 stimulates the tyrosinase and TyrpI promoter activities, while TFEB acts only on the TyrpI promoter. TFE3 and TFEB elicit their effects mainly through the binding to Mbox (AGTCATGTGCT) and Ebox motifs (CATGTG) of tyrosinase and TyrpI promoters. In B16 melanoma cells, the high basal expression of TFE3 is down-regulated by forskolin and by alphaMSH. Interestingly, endogenous TFE3 cannot bind as homodimers to the Mbox, and we did not detect TFE3/Mi heterodimers. According to these data, TFE3 is clearly endowed with the capacity to regulate tyrosinase and TyrpI gene expression. However, TFE3 binding to the melanogenic gene promoters is hindered, thereby preventing its potential melanogenic action. In specific physiological or pathological conditions, the recovery of its binding function would make TFE3 an important element in melanogenesis regulation.
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Affiliation(s)
- C Verastegui
- Institut National de la Santé et de la Recherche Médicale U385, Faculté de Médecine, Nice, France
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25
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26
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Murray D, Precht P, Balakir R, Horton WE. The transcription factor deltaEF1 is inversely expressed with type II collagen mRNA and can repress Col2a1 promoter activity in transfected chondrocytes. J Biol Chem 2000; 275:3610-8. [PMID: 10652357 DOI: 10.1074/jbc.275.5.3610] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The regulation of Col2a1, which encodes type II collagen, likely results from a balance of both positive and negative proteins. Here we present evidence that the transcription factor deltaEF1 participates in the negative regulation of Col2a1 transcription. A deletion analysis suggested that a region between -100 and -307 of the rat Col2a1 gene was required for activity in differentiating chick limb bud mesenchymal cells; however, mutation of a conserved E2 box site in this region actually increased promoter activity. Supershift analysis demonstrated that deltaEF1, a known transcriptional repressor, bound to the E2 box in a sequence-dependent manner. Chick limb bud mesenchymal cells, which do not express type II collagen, expressed abundant deltaEF1 mRNA, but, following differentiation in micromass culture, deltaEF1 mRNA expression was lost. Primary embryonic chick sternal chondrocytes, which express abundant type II collagen, displayed minimal levels of deltaEF1 mRNA. The inhibition of Col2a1 transcription following treatment of chick sternal chondrocytes with growth factors was accompanied by increased deltaEF1 expression. Overexpression of deltaEF1 in differentiated chondrocytes resulted in decreased expression of a reporter construct containing a collagen II promoter/enhancer insert; however, this negative regulation was not dependent on the proximal E2 box. This is the first report of a specific transcription factor involved in the negative regulation of Col2a1.
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Affiliation(s)
- D Murray
- Laboratory of Biological Chemistry, Gerontology Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224, USA
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27
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Abstract
AbstractProper regulation of the human CD34 gene requires a combinatorial action of multiple proximal and long-range, ciselements. This report shows that, like the murine CD34 5′ untranslated region (UTR), the corresponding region of the human CD34 gene is necessary for optimal promoter activity. We localized the most critical element of this region to base pairs +48/+75. Through oligonucleotide competition and antibody supershift experiments in electrophoretic mobility shift assays, we found that this sequence contains a binding site (CCAAT box) for the transcription factor NFY (nuclear factor Y), a factor mediating cell type-specific and cell-cycle regulated expression of genes. Mutating this site led to a 5-fold decrease in CD34 promoter activity in transient transfection experiments. Interestingly, NFY binds adjacently to the earlier identified c-myb binding site. Here we show that both binding sites are important for CD34 promoter function: mutating either site alone decreased CD34 promoter-driven reporter gene activity 4-fold. We also show that the integrity of the c-myb binding site is necessary for stabilization of NFY binding to its site. Such cooperation between c-myb, which is expressed in early hematopoietic cells, and NFY, which is expressed in many cell types, might contribute to specific activation of CD34 in stem cells. The CCAAT box motif was also noted in the 5′ UTR of the murine CD34 gene, however, NFY did not bind to this region. Thus, our results indicate that the functional similarities between the human and murine CD34 5′ UTRs are achieved through different molecular mechanism(s).
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28
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Abstract
Proper regulation of the human CD34 gene requires a combinatorial action of multiple proximal and long-range, ciselements. This report shows that, like the murine CD34 5′ untranslated region (UTR), the corresponding region of the human CD34 gene is necessary for optimal promoter activity. We localized the most critical element of this region to base pairs +48/+75. Through oligonucleotide competition and antibody supershift experiments in electrophoretic mobility shift assays, we found that this sequence contains a binding site (CCAAT box) for the transcription factor NFY (nuclear factor Y), a factor mediating cell type-specific and cell-cycle regulated expression of genes. Mutating this site led to a 5-fold decrease in CD34 promoter activity in transient transfection experiments. Interestingly, NFY binds adjacently to the earlier identified c-myb binding site. Here we show that both binding sites are important for CD34 promoter function: mutating either site alone decreased CD34 promoter-driven reporter gene activity 4-fold. We also show that the integrity of the c-myb binding site is necessary for stabilization of NFY binding to its site. Such cooperation between c-myb, which is expressed in early hematopoietic cells, and NFY, which is expressed in many cell types, might contribute to specific activation of CD34 in stem cells. The CCAAT box motif was also noted in the 5′ UTR of the murine CD34 gene, however, NFY did not bind to this region. Thus, our results indicate that the functional similarities between the human and murine CD34 5′ UTRs are achieved through different molecular mechanism(s).
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29
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Crissey MA, Leu JI, DeAngelis RA, Greenbaum LE, Scearce LM, Kovalovich K, Taub R. Liver-specific and proliferation-induced deoxyribonuclease I hypersensitive sites in the mouse insulin-like growth factor binding protein-1 gene. Hepatology 1999; 30:1187-97. [PMID: 10534340 DOI: 10.1002/hep.510300520] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
The insulin-like growth factor binding protein-1 (IGFBP-1) gene is highly expressed in fetal, perinatal, and regenerating liver. Up-regulation is transcriptionally mediated in regenerating liver and occurs in the first few minutes to hours after partial hepatectomy. In transgenic mice a 970-bp region from -776 to +151 of the IGFBP-1 promoter was sufficient for tissue-specific and induced expression of the gene in fetal and hepatectomized livers. However weak and/or poorly regulated expression in some transgenic lines suggested the existence of other regulatory regions. Here, genomic clones containing large regions 5' of the mouse IGFBP-1 gene sequence were isolated, subcloned, and sequenced. Deoxyribonuclease I (DNaseI) hypersensitivity analyses identified clusters of tissue-specific nuclease-sensitive sites in the promoter region, -100 to -300, -2,300, -3,100, and -5,000 along with other weak sites. After partial hepatectomy, enhanced sensitivity and/or novel sites were detected in the -100/-300, -5,000, and -3,100 regions, the promoter region remaining the most hypersensitive. A subset of these sites was present in fetal and perinatal livers. Novel tissue-specific sites that interacted with C/EBP and hepatic nuclear factor 3 (HNF3) transcription factors were identified in the -3,100 region. A hepatectomy-induced DNA binding complex containing the transcription factor USF1 was identified within the -100 to -300 region of the promoter. These results suggested that a complex array of tissue-specific and hepatic proliferation-induced transcription factors combine to regulate both the proximal promoter and more distal regulatory elements of the IGFBP-1 gene.
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Affiliation(s)
- M A Crissey
- Department of Genetics, Division of Gastroenterology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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Khodadoust MM, Khan KD, Bothwell ALM. Complex Regulation of Ly-6E Gene Transcription in T Cells by IFNs. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.2.811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The complexity of IFN-mediated regulation of the murine Ly-6E gene in T cell lines is highlighted by the following observations: 1) multiple regulatory regions are present within different parts of the Ly-6E promoter and are necessary for IFN inducibility of the Ly-6E gene, 2) multiple transcription factors including Oct-1 and Oct-2 and the high mobility group (HMG) protein HMGI(Y) bind to regulatory elements present within the G region required for both IFN-αβ and IFN-γ responses, 3) mutational analysis of the G region reveals that a complex interaction exists between the factors binding to this region as shown by their mutual interdependence for detection in DMSA, and 4) inhibition of expression of HMG proteins by antisense HMGI-C RNA in EL4 cells causes the loss of IFN-αβ and IFN-γ inducibility of the endogenous Ly-6 gene. These findings taken together suggest that, in response to IFN treatment, an HMG protein-dependent complex involving multiple regulatory factors is assembled and is required for IFN inducibility of the Ly-6E gene.
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Affiliation(s)
- Mehran M. Khodadoust
- *Section of Immunobiology, Yale University School of Medicine, New Haven, CT 06520; and
| | - Khuda Dad Khan
- †Department of Medicine, Divisions of Hematology and Oncology, Duke University Medical Center, Durham, NC 27710
| | - Alfred L. M. Bothwell
- *Section of Immunobiology, Yale University School of Medicine, New Haven, CT 06520; and
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O'Riordan M, Grosschedl R. Coordinate regulation of B cell differentiation by the transcription factors EBF and E2A. Immunity 1999; 11:21-31. [PMID: 10435576 DOI: 10.1016/s1074-7613(00)80078-3] [Citation(s) in RCA: 240] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The transcription factors EBF and E2A are required at a similar step in early B cell differentiation. EBF and E2A synergistically upregulate transcription of endogenous B cell-specific genes in a non-B cell line. Here, we examine a genetic collaboration between these factors in regulating B lymphopoiesis. We find that Ebf+/- E2a+/- mice display a marked defect in pro-B cell differentiation at a stage later than observed in the single homozygous mutant mice. Pro-B cells from Ebf+/- E2a+/- mice show reduced expression of lymphoid-specific transcripts, including Pax5, Rag1, Rag2, and mb-1. We also show that EBF directly binds and activates the Pax5 promoter. Together, these data show collaboration between EBF and E2A and provide insight into the hierarchy of transcription factors that regulate B lymphocyte differentiation.
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Affiliation(s)
- M O'Riordan
- Howard Hughes Medical Institute, Department of Microbiology and Immunology, University of California, San Francisco 94143, USA
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Kiso S, Kawata S, Tamura S, Umeki S, Ito N, Tsushima H, Yamada A, Miyagawa J, Higashiyama S, Taniguchi N, Matsuzawa Y. Effects of exogenous human heparin-binding epidermal growth factor-like growth factor on DNA synthesis of hepatocytes in normal mouse liver. Biochem Biophys Res Commun 1999; 259:683-7. [PMID: 10364479 DOI: 10.1006/bbrc.1999.0845] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Heparin-binding epidermal growth factor-like growth factor (HB-EGF) has been reported to stimulate DNA synthesis of the hepatocytes in culture and highly express in regenerating rat liver after partial hepatectomy. We examined mitogenic effects and activation of transcription factors caused by exogenous human HB-EGF (hHB-EGF) in mouse liver. The mean labeling index in hepatocytes of hHB-EGF-injected mice was 2.6%, a significant increase over that in saline-injected controls (under 0.01%). By exogenous hHB-EGF injection, activation of transcription factors such as nuclear factor (NF)-kappaB and activator factor (AP)-1 was observed in the liver. By Northern blot analysis, hepatocyte growth factor (HGF) gene expression in the liver was found to be induced in the hHB-EGF-injected mice. In conclusion, intravenously injected hHB-EGF showed a limited but definite effect on the DNA synthesis of hepatocytes in the mice liver. HB-EGF may serve as a hepatotrophic factor in vivo.
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Affiliation(s)
- S Kiso
- Second Department of Internal Medicine, Department of Biochemistry, Osaka University Medical School, 2-2 Yamadaoka, Osaka, Suita, 565-0871, Japan.
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Gemel J, Jacobsen C, MacArthur CA. Fibroblast growth factor-8 expression is regulated by intronic engrailed and Pbx1-binding sites. J Biol Chem 1999; 274:6020-6. [PMID: 10026229 DOI: 10.1074/jbc.274.9.6020] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fibroblast growth factor-8 (FGF8) plays a critical role in vertebrate development and is expressed normally in temporally and spatially restricted regions of the vertebrate embryo. We now report on the identification of regions of Fgf8 important for its transcriptional regulation in murine ES cell-derived embryoid bodies. Stable transfection of ES cells, using a human growth hormone reporter gene, was employed to identify regions of the Fgf8 gene with promoter/enhancer activity. A 2-kilobase 5' region of Fgf8 was shown to contain promoter activity. A 0.8-kilobase fragment derived from the large intron of Fgf8 was found to enhance human growth hormone expressed from the Fgf8 promoter 3-4-fold in an orientation dependent manner. The intronic fragment contains DNA-binding sites for the AP2, Pbx1, and Engrailed transcription factors. Gel shift and Western blot experiments documented the presence of these transcription factors in nuclear extracts from ES cell embryoid bodies. In vitro mutagenesis of the Engrailed or Pbx1 site demonstrated that these sites modulate the activity of the intronic fragment. In addition, in vitro mutagenesis of both Engrailed and Pbx1 sites indicated that other unidentified sites are responsible for the transcriptional enhancement observed with the intronic fragment.
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Affiliation(s)
- J Gemel
- Department of Pediatrics and Pathology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Park ST, Sun XH. The Tal1 oncoprotein inhibits E47-mediated transcription. Mechanism of inhibition. J Biol Chem 1998; 273:7030-7. [PMID: 9507011 DOI: 10.1074/jbc.273.12.7030] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Tal1 oncogene is a class II basic helix-loop-helix (bHLH) transcription factor, overexpressed in as much as 60% of T cell acute lymphoblastic leukemia cases. Like other class II bHLH proteins, Tal1 can heterodimerize with the class I bHLH proteins, such as E47, and bind to a DNA recognition sequence termed E box. Therefore, it is believed that the oncogenic capacity of Tal1 lies in its ability, as a heterodimer with E47, to activate aberrantly a set of "leukemogenic" genes in T cells. However, compared with E47 homodimers, Tal1/E47 heterodimers are very poor transactivators. Thus the effect of Tal1 is actually to inhibit E47 homodimer activity. Here we propose that the transforming properties of Tal1 are the result of its ability to inhibit E47 activity. We address the mechanism of Tal1 inhibition and demonstrate that Tal1/E47 heterodimers cannot activate transcription because their respective activation domains are incompatible. Furthermore, we present data showing that Tal1 can inhibit E47-mediated activation of the CIP1 gene. Finally, we demonstrate that Tal1 inhibits E47 activity in leukemic T cells.
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Affiliation(s)
- S T Park
- Department of Cell Biology, New York University Medical Center, New York, New York 10016, USA
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35
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Abstract
CDC37 and the chaperone protein, Hsp90, form a complex that binds to several kinases, resulting in stabilization and promotion of their activity. CDC37 also binds DNA and glycosaminoglycans in a sequence-specific manner. In this study, we further characterize chick CDC37 and examine the organization of the CDC37 gene. Chick CDC37 is a approximately 50-kDa protein encoded by an mRNA of approximately 1.7 kilobases. The CDC37 gene is approximately 8.5 kilobases and contains 8 exons and 7 introns of various sizes. The presumptive promoter and 5'-flanking regions contain an E2 box and consensus binding sites for SP1, for the S8 homeodomain protein, and for two zinc finger clusters within the myeloid progenitor transcription factor, MZF1. Particularly striking is a approximately 470-base pair region composed of a highly repetitive 10-11-base pair sequence, (T/C)gCTAT(A/G)GGG(A/T) (where g represents the additional G present in the 11-base pair sequence). This region includes 15 copies of the sequence, TATGGGGA, which conforms to the DNA consensus sequence recognized by one of the zinc finger clusters in MZF1. These findings emphasize the potential importance of CDC37 in regulation of cellular behavior during tissue development and reorganization.
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Affiliation(s)
- L Huang
- Department of Anatomy and Cellular Biology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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36
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Chavali GB, Nagpal S, Majumdar SS, Singh O, Salunke DM. Helix-loop-helix motif in GnRH associated peptide is critical for negative regulation of prolactin secretion. J Mol Biol 1997; 272:731-40. [PMID: 9368654 DOI: 10.1006/jmbi.1997.1274] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The GnRH associated prolactin inhibiting factor (GAP) reveals the signature sequence associated with the helix-loop-helix structural motif. A number of different peptide fragments of GAP were designed, synthesized and analysed by circular dichroism and by an in vivo assay for prolactin secretion inhibiting activity. Peptides corresponding to the two individual alpha-helices and a 44-residue peptide comprising the entire helix-loop-helix motif show significant helical propensity in circular dichroism spectra. However, a peptide corresponding to the loop sequence shows no helical propensity. Albeit, the peptide corresponding to helix-loop-helix motif was found to inhibit prolactin secretion and augment circulating levels of gonadotropins in the in vivo assay; other shorter peptides did not show such activity. The activity profile of the 44-residue peptide was biphasic and very similar to that of the recombinant GAP. Thus, the prolactin inhibiting activity of this factor is defined by its helix-loop-helix motif as in the case of the transcription factors of developmental genes. The structural features of a homology-based model of GAP in complex with E47, a ubiquitous HLH-type developmental gene regulator, are consistent with the structural requirements of the negative regulation of transcription by helix-loop-helix proteins.
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Affiliation(s)
- G B Chavali
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
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37
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Moran D, Galperin E, Horowitz M. Identification of factors regulating the expression of the human glucocerebrosidase gene. Gene 1997; 194:201-13. [PMID: 9272862 DOI: 10.1016/s0378-1119(97)00148-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Gaucher disease, the most prevalent sphingolipid disorder, is characterized by an accumulation of sphingolipids mainly in cells of the reticuloendothelial cells, and is due to decreased activity of the lysosomal enzyme glucocerebrosidase (GCase). The corresponding gene is expressed differentially, namely in different cell types there are different GCase steady-state mRNA levels. Electrophoretic mobility shift assays, DNase footprinting and chloramphenicol acetyl transferase assays were employed in order to unravel some of the transcription factors responsible for the differential expression of the glucocerebrosidase (gcs) gene. The results indicate that OCTA binding protein, AP-1, PEA3 and a CAAT binding protein participate in regulating the expression of the gcs gene. The availability of the transcription factors seems to control the level of transcription of the gcs gene.
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Affiliation(s)
- D Moran
- Department of Cell Research and Immunology, Tel-Aviv University, Ramat-Aviv, Israel
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38
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Sigvardsson M, O'Riordan M, Grosschedl R. EBF and E47 collaborate to induce expression of the endogenous immunoglobulin surrogate light chain genes. Immunity 1997; 7:25-36. [PMID: 9252117 DOI: 10.1016/s1074-7613(00)80507-5] [Citation(s) in RCA: 205] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Early B cell factor (EBF) and E47 participate in the transcriptional control of early B lymphocyte differentiation. With the aim of identifying genetic targets for these transcription factors, we stably transfected cDNAs encoding EBF or a covalent homodimer of E47, individually or together, into immature hematopoietic Ba/F3 cells, which lack both factors. In combination, EBF and E47 induce efficient expression of the endogenous immunoglobulin surrogate light chain genes, lambda5 and VpreB, whereas other pre-B cell-specific genes remain silent. Multiple functionally important EBF and E47 binding sites were identified in the lambda5 promoter/enhancer region, indicating that lambda5 is a direct genetic target for these transcription factors. Taken together, these data suggest that EBF and E47 synergize to activate expression of a subset of genes that define an early stage of the B cell lineage.
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Affiliation(s)
- M Sigvardsson
- Howard Hughes Medical Institute, Department of Microbiology, University of California, San Francisco 94143-0414, USA
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39
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Chu C, Cogswell J, Kohtz DS. MyoD functions as a transcriptional repressor in proliferating myoblasts. J Biol Chem 1997; 272:3145-8. [PMID: 9013546 DOI: 10.1074/jbc.272.6.3145] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The myogenic basic helix-loop-helix (myo-bHLH) proteins are a family of transcriptional regulators expressed in myoblasts and differentiated skeletal muscle. Ectopic expression of myo-bHLH regulators transdetermines some fibroblast cell lines into myoblasts, which exit the cell cycle and differentiate into skeletal muscle when cultured in low mitogen medium. While members of the myo-bHLH family have been shown to function as transcriptional activators in differentiating muscle, the molecular basis of their function in proliferating myoblasts has not been elucidated. In this report, we present evidence that MyoD functions as a transcriptional repressor in myoblasts. We show that transcription from a cyclin B1 promoter construct is repressed in proliferating myoblasts and that repression is mediated by a pair of MyoD binding sites. We also show that transcription from the cyclin B1 promoter is repressed in proliferating C3H10T1/2 cells by ectopic expression of MyoD. These results demonstrate that MyoD can repress transcription of specific genes in proliferating cells, a novel function that may be important to maintenance of the myogenic phenotype and to cell cycle regulation in myoblasts.
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Affiliation(s)
- C Chu
- Department of Pathology, Mount Sinai School of Medicine, New York, New York 10029, USA
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40
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Kho CJ, Huggins GS, Endege WO, Hsieh CM, Lee ME, Haber E. Degradation of E2A proteins through a ubiquitin-conjugating enzyme, UbcE2A. J Biol Chem 1997; 272:3845-51. [PMID: 9013644 DOI: 10.1074/jbc.272.6.3845] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The helix-loop-helix E2A proteins (E12 and E47) govern cellular growth and differentiation. To identify binding partners that regulate the function of these ubiquitous transcription factors, we screened for proteins that interacted with the C terminus of E12 by the yeast interaction trap. UbcE2A, a rat enzyme that is highly homologous to and functionally complements the yeast ubiquitin-conjugating enzyme UBC9, was identified and cloned. UbcE2A appears to be an E2A-selective ubiquitin-conjugating enzyme because it interacts specifically with a 54-amino acid region in E47-(477-530) distinct from the helix-loop-helix domain. In contrast, most of the UbcE2A protein is required for interaction with an E2A protein. The E2A proteins appear to be degraded by the ubiquitin-proteasome pathway because the E12 half-life of 60 min is extended by the proteasome inhibitor MG132, and E12 is multi-ubiquitinated in vivo. Finally, antisense UbcE2A reduces E12 degradation. By participating in the degradation of the E2A proteins, UbcE2A may regulate cell growth and differentiation.
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Affiliation(s)
- C J Kho
- Cardiovascular Biology Laboratory, Harvard School of Public Health, Boston, Massachusetts 02115, USA
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41
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Bain G, Robanus Maandag EC, te Riele HP, Feeney AJ, Sheehy A, Schlissel M, Shinton SA, Hardy RR, Murre C. Both E12 and E47 allow commitment to the B cell lineage. Immunity 1997; 6:145-54. [PMID: 9047236 DOI: 10.1016/s1074-7613(00)80421-5] [Citation(s) in RCA: 153] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The E2A gene products, E12 and E47, are required for proper B cell development. Mice lacking the E2A gene products generate only a very small number of B220+ cells, which lack immunoglobulin DJ(H) rearrangements. We have now generated mice expressing either E12 or E47. B cell development in mice expressing E12 but lacking E47 is perturbed at the pro-B cell stage, and these mice lack IgM+B220+ B cells in both bone marrow and spleen. IgM+B220+ B cells can be detected, albeit at significantly reduced levels, in the bone marrow and spleen of mice lacking E12. Ectopic expression of both E12 and E47 in a null mutant background shows that E12 and E47 act in concert to promote B lineage development. Taken together, the data indicate that both E12 and E47 allow commitment to the B cell lineage and act synergistically to promote B lymphocyte maturation.
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Affiliation(s)
- G Bain
- Department of Biology, University of California, San Diego, La Jolla 92093, USA
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42
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Moss JB, Olson EN, Schwartz RJ. The myogenic regulatory factor MRF4 represses the cardiac alpha-actin promoter through a negative-acting N-terminal protein domain. J Biol Chem 1996; 271:31688-94. [PMID: 8940190 DOI: 10.1074/jbc.271.49.31688] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Cardiac alpha-actin is activated early during the development of embryonic skeletal muscle and cardiac myocytes. The gene product remains highly expressed in adult striated cardiac muscle yet is dramatically reduced in skeletal muscle. Activation and repression of cardiac alpha-actin gene activity in developing skeletal muscle correlates with changes in the relative content of the four myogenic regulatory factors. Cardiac alpha-actin promoter activity, assessed in primary chick myogenic cultures, was activated by endogenous myogenic regulatory factors but was inhibited in the presence of co-expressed MRF4. By exchanging N- and C-terminal domains of MRF4 and MyoD, the N terminus of MRF4 was identified as the mediator of repressive activity, revealing a novel negative regulatory role for MRF4. The relative ratios of myogenic regulatory factors may have fundamental roles in selecting specific muscle genes for activation and/or repression.
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Affiliation(s)
- J B Moss
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
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43
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Lenka N, Basu A, Mullick J, Avadhani NG. The role of an E box binding basic helix loop helix protein in the cardiac muscle-specific expression of the rat cytochrome oxidase subunit VIII gene. J Biol Chem 1996; 271:30281-9. [PMID: 8939982 DOI: 10.1074/jbc.271.47.30281] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We have characterized the rat gene for muscle-specific cytochrome oxidase VIII (COX VIII(H)) and mapped the distal promoter region responsible for transcription activation in C2C12 skeletal myocytes and H9C2 cardiomyocytes. In both cell types, the promoter elements responding to the induced differentiation of myocytes map to two E boxes, designated as E1 and E2 boxes with a core sequence of CAGCTG. Gel mobility shift analysis showed that both E1 and E2 box motifs form complexes with nuclear extracts from H9C2 cardiomyocytes that were supershifted with monoclonal antibody to E2A but not with antibody to myo-D. Extracts from induced and uninduced H9C2 cardiomyocytes yielded different gel mobility patterns and also different E2A antibody supershifts suggesting a difference in the DNA-bound protein complexes cross-reacting with the E2A antibody. Transcriptional activity of the promoter construct containing intact E boxes was inhibited by coexpression with Id in differentiated H9C2 cardiomyocytes. Our results show the involvement of an E box binding basic helix loop helix protein in the cardiac muscle-specific regulation of the COX VIII(H) promoter.
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Affiliation(s)
- N Lenka
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6047, USA.
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44
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Quesenberry PJ, Iscove NN, Cooper C, Brady G, Newburger PE, Stein GS, Stein JS, Reddy GPV, Pearson-White S. Expression of basic helix-loop-helix transcription factors in explant hematopoietic progenitors. J Cell Biochem 1996. [DOI: 10.1002/(sici)1097-4644(19960601)61:3<478::aid-jcb15>3.0.co;2-f] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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45
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Quesenberry PJ, Iscove NN, Cooper C, Brady G, Newburger PE, Stein GS, Stein JS, Reddy GP, Pearson-White S. Expression of basic helix-loop-helix transcription factors in explant hematopoietic progenitors. J Cell Biochem 1996; 61:478-88. [PMID: 8761952 DOI: 10.1002/(sici)1097-4644(19960601)61:3%3c478::aid-jcb15%3e3.0.co;2-f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The basic helix-loop-helix (bHLH) transcription factors form heterodimers and control steps in cellular differentiation. We have studied four bHLH transcription factors, SCL, lyl-1, E12/E47, and ld-1, in individual lineage-defined progenitors and hematopoietic growth factor-dependent cell lines, evaluating mRNA expression and the effects of growth factors and cell cycle phase on this expression. Single lineage-defined progenitors selected from early murine colony starts and grown under permissive conditions were analyzed by RT-PCR. SCL and E12/E47 were expressed in the vast majority of tri-, bi-, and unilineage progenitors of erythroid, macrophage, megakaryocyte, and neutrophil lineages. Expression for E12/E47 was not seen in unilineage megakaryocyte and erythroid or bilineage neutrophil/mast cell progenitors. Lyl-1 showed a more restricted pattern of expression, although expression was seen in some bi- and unilineage progenitors. No expression was detected in erythroid, erythroid-megakaryocyte-macrophage, macrophage-neutrophil, macrophage, or megakaryocytic progenitors. Id-1, an inhibitory bHLH transcription factor, was also widely expressed in all bi- and unilineage progenitors; only the trilineage erythroid-megakaryocyte-macrophage progenitors failed to show expression. Expression of these factors within a progenitor class was generally heterogeneous, with some progenitors showing expression and some not. This was seen even when two sister cells from the same colony start were analyzed. Id-1, but not E12/E47, mRNA was increased in FDC-P1 and MO7E hematopoietic cell lines after exposure to IL-3 or GM-CSF. Id-1, E12, and lyl-1 showed marked variation at different points in cell cycle in isoleucine-synchronized FDC-P1 cells. These results suggest that SCL, lyl-1, E12/E47, and Id-1 are important in hematopoietic progenitor cell regulation, and that their expression in hematopoietic cells varies in response to cytokines and/or during transit through cell cycle.
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Affiliation(s)
- P J Quesenberry
- Cancer Center, University of Massachusetts Medical Center, Worcester 01605, USA
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46
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Fitzsimmons D, Hagman J. Regulation of gene expression at early stages of B-cell and T-cell differentiation. Curr Opin Immunol 1996; 8:166-74. [PMID: 8725939 DOI: 10.1016/s0952-7915(96)80054-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The expression of distinct sets of genes at different stages of B-lymphocyte and T-lymphocyte differentiation is controlled at the level of transcription. A number of recent studies have described interactions between transcription factors in lymphocytes that provide new insights into mechanisms regulating gene expression. These mechanisms include the assembly of higher order nucleoprotein complexes and other protein-protein interactions that enhance the functional specificity of transcriptional regulators in lymphocytes.
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Affiliation(s)
- D Fitzsimmons
- National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado 80206, USA
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47
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Glozak MA, Blomberg BB. The human lambda immunoglobulin enhancer is controlled by both positive elements and developmentally regulated negative elements. Mol Immunol 1996; 33:427-38. [PMID: 8676894 DOI: 10.1016/0161-5890(95)00146-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We have recently reported the localization of the first transcriptional enhancer in the human lambda (lambda) immunoglobulin light chain locus. Enhancer activity was contained on a 1.2 kb SstI fragment, with partial activity retained on a core 111 bp PstI-SstI fragment. This enhancer is located 11.7 kb downstream of C lambda 7, the most 3' lambda constant region gene. Using a chloramphenicol acetyl transferase (CAT) assay system, we have now determined the boundaries of the complete enhancer and find it is two- to four-fold as active as the core fragment in both pre-B and B cell lines. Interestingly, a larger fragment, containing the complete enhancer as well as 5' and 3' flanking sequences has four- to eight-fold reduced activity when tested in pre-B cell lines, but full activity in B cell lines. This suggests the presence of developmentally regulated negative elements flanking the human lambda enhancer which prevent or reduce its activity at a developmentally incorrect time. By using in vivo footprinting we have begun to examine the protein interactions within this enhancer in a more physiologically relevant manner and have identified motifs which are shared with the murine lambda enhancers, as well as motifs unique to the human lambda enhancer.
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Affiliation(s)
- M A Glozak
- Department of Microbiology and Immunology, University of Miami School of Medicine, FL 33101, USA
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48
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Marlow SA, Kay PH, Papadimitriou JM. Polymorphism of the mouse E2A gene due to an intronic deletion of 536 bp. Gene 1996; 168:143-9. [PMID: 8654934 DOI: 10.1016/0378-1119(95)00752-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Examination of genetic polymorphism of the transcription factor-encoding gene E2A in laboratory and wild mice by Southern blotting has revealed the presence of two alleles. The most frequent allele is found in Mus musculus (Mm) musculus, as well as Mm domesticus. The less common allele is restricted to the Mm domesticus subspecies. Characterisation of these alleles has shown that the less common allele contains a deletion of approx. 500 bp located within a 1.8-kb intron immediately upstream from the E12 basic helix-loop-helix exon. DNA sequencing determined the deletion to span 536 bp including nucleotides 1045-1580 of the intron within the common allele. The deleted region includes several sequences with similarity to gene regulatory motifs; however, expression of E12 and intron splicing appeat unaltered. The occurrence of an identical deletion in mice from different geographical regions suggests that the uncommon allele may have a long evolutionary history.
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Affiliation(s)
- S A Marlow
- Department of Pathology, University of Western Australia, Nedlands
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49
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Lopez-Bayghen E, Vega A, Cadena A, Granados SE, Jave LF, Gariglio P, Alvarez-Salas LM. Transcriptional analysis of the 5'-noncoding region of the human involucrin gene. J Biol Chem 1996; 271:512-20. [PMID: 8550612 DOI: 10.1074/jbc.271.1.512] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Human involucrin whose gene transcription is directed by a 2456-nucleotide (nt) 5'-noncoding region is a structural component of the epithelial cornified layer. Transient transfection assays demonstrated that this region is transcriptionally active in multiplying keratinocytes and is enhanced by 2 mM CaCl2 treatment. Calcium-independent transcriptional activity and the interaction with the AP-1 transcriptional factor was located on the proximal part (nt -159 to -1) of the 5'-noncoding region. However, CaCl2 responsiveness was mapped to a distal 1185-nt fragment (nt -2456 to -1272). Moreover, this fragment potentiated the Herpes simplex thymidine kinase promoter in normal keratinocytes and is responsive to calcium treatment in a cell type-specific manner. Interestingly, the absence of a 491-nt fragment located between the two enhancer domains (nt -651 to -160) resulted in transcriptional activation in multiplying keratinocytes. This fragment interacts with AP-1 and the YY1 transcriptional silencer. It is concluded that human involucrin 5'-noncoding region contains at least three regulatory domains, a distal CaCl2-responsive enhancer, a putative transcriptional silencer (that interacts with AP-1 and YY1), and a proximal enhancer/promoter (that interacts with AP-1). Thus, this study demonstrates the presence of particular transcriptional factors can potentially regulate the human involucrin expression.
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Affiliation(s)
- E Lopez-Bayghen
- Departamento de Genetica y Biologia Molecular, Centro de Investigacion y Estudios Avanzados del Instituto Politecnico Nacional, Mexico, Distrito Federal, Mexico
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50
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Engeland K, Andrews NC, Mathey-Prevot B. Multiple proteins interact with the nuclear inhibitory protein repressor element in the human interleukin-3 promoter. J Biol Chem 1995; 270:24572-9. [PMID: 7592676 DOI: 10.1074/jbc.270.41.24572] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
T cell expression of interleukin 3 (IL-3) is directed by positive and negative cis-acting DNA elements clustered within 300 base pairs of the transcriptional start site. A strong repressor element, termed nuclear inhibitory protein (NIP), was previously mapped to a segment of the IL-3 promoter between nucleotides -271 and -250. Functional characterization of this element demonstrates that it can mediate repression when linked in cis to a heterologous promoter. DNA binding experiments were carried out to characterize the repressor activity. Using varying conditions, three distinct complexes were shown to interact specifically with the NIP region, although only one correlates with repressor activity. Complex 1 results from binding of a ubiquitous polypeptide that recognizes the 3' portion of this sequence and is not required for repression. Complex 2 corresponds to binding of transcription factor (upstream stimulatory factor) to an E-box motif in the 5' portion of the NIP region. DNA binding specificity of complex 3 overlaps with that of upstream stimulatory factor but is clearly distinct. To determine which of the latter two complexes represents NIP activity, we incorporated small alterations into the NIP site of an IL-3 promoter-linked reporter construct and examined their effects on NIP-mediated repression. Functional specificity for repression matches the DNA binding specificity of complex 3; both repressor activity and complex 3 binding require the consensus sequence CTCACNTNC.
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Affiliation(s)
- K Engeland
- Department of Pediatric Oncology, Harvard Medical School, Boston, Massachusetts 02115, USA
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