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Structure and regulation of the human NeuroD (BETA2/BHF1) gene

MOLECULAR BRAIN RESEARCH 1999年第2期69卷 223-231页

作者： Miyachi, T Maruyama, H Kitamura, T Nakamura, S Kawakami, H Hiroshima Univ Sch Med Dept Internal Med 3 Minami Ku Hiroshima 7348551 Japan

In this study, we isolated and characterized the human NeuroD (BETA2/BHF1) gene. This gene was found to consist of two exons and one intron. The promoter regions were well-conserved compared with the mouse NeuroD gene. Two transcription start points (TSPs) were determined by the oligo-capping method. One TATA box was located at -31 bp from the lower TSP. The results of a transient transfection assay using the human neuroblastoma cell line IMR-32 and hamster insulin tumor cell line HIT-T15 suggested that there are at least three positive regulatory regions in the promoter. In these regions, four E boxes (CANNTG), named the E1 to E4 boxes, and two GC boxes were present. Cotransfection of the NeuroD expression vector into IMR-32 cells enhanced the NeuroD promoter activity by about 4-fold. A deletion and mutation analysis revealed that the E1 and E4 boxes, especially the E1 box, are associated with autoactivation and that E2 and E3 boxes are not associated with autoactivation. As mutation analysis of E3 box showed a decrease in the enhancer activity to the basal level, it showed that the E3 box is important to activate the NeuroD transcription. These results raised the possibility that the NeuroD gene expression is positively regulated through the E box sequence, not only by NeuroD itself but also by another E box binding protein. (C) 1999 Elsevier Science B.V. All rights reserved.

关键词： NeuroD (BETA2/BHF1) neuronal development promoter autoactivation basic helix-loop-helix

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Alternative splicing and embryonic expression of the Xenopus mad4 bHLH gene

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DEVELOPMENTAL DYNAMICS 1999年第2期215卷 170-178页

作者： Newman, CS Krieg, PA Univ Texas Dept Zool Austin TX 78712 USA Univ Texas Inst Cellular & Mol Biol Austin TX 78712 USA

The cell proliferative activity of the Myc family of basic helix-loop-helix/leucine zipper (bHLHZip) transcription factors is dependent upon binding to the ubiquitous Max protein. In the absence of heterodimerization with Max, Myc protein is unable to efficiently bind to DNA and activate transcription. Members of the Mad family of transcription factors are thought to modulate the cell proliferative effects of the c-myc proto-oncogene by binding to Max, directly competing with the Myc protein for both heterodimerization and DNA binding. Consistent with a role in down-regulating cell division, the murine mad genes are expressed in embryonic tissues undergoing differentiation, often during or shortly after the down-regulation of myc gene expression. Here, we report the isolation and characterization of the first Xenopus mad family member, Xmad4. Maternal Xmad4 transcripts are present at high levels in the oocyte and in the cleavage stage embryo, but almost disappear by the neurula stage. Zygotic expression of the Xmad4 gene is initiated in the epidermis of the late neurula stage, and shortly thereafter, Xmad4 is transiently detectable in the cement and hatching glands. At later stages, expression is also observed in the developing pronephros and liver. Unlike the murine mad4 gene, we find that multiple Xmad4 splice variants exist in Xenopus and that these variants are differentially expressed in both the embryo and the adult. Despite the demonstrated antagonistic role of Mad proteins in the regulation of Myc activity, we show that the over-expression of Xmad4 in the cleavage-stage embryo has no detectable phenotypic effect, suggesting that Myc function is dispensable during early embryonic development. Dev Dyn 1999;215:170-178. (C) 1999 Wiley-Liss, Inc.

关键词： Xenopus mad max myc basic helix-loop-helix

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The WRPW motif of the hairy-related basic helix-loop-helix repressor proteins acts as a 4-amino-acid transcription repression and protein-protein interaction domain

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MOLECULAR AND CELLULAR BIOLOGY 1996年第6期16卷 2670-2677页

作者： Fisher, AL Ohsako, S Caudy, M CORNELL UNIV COLL MED DEPT ANAT & CELL BIOL NEW YORK NY 10021 USA TOKYO METROPOLITAN INST NEUROSCI DEPT CELL BIOL TOKYO 183 JAPAN

Hairy-related proteins include the Drosophila Hairy and Enhancer of Split proteins and mammalian Hes proteins. These proteins are basic helix-loop-helix (bHLH) transcriptional repressors that control cell fate decisions such as neurogenesis or myogenesis in both Drosophila melanogaster and mammals. Hairy-related proteins are site-specific DNA-binding proteins defined by the presence of both a repressor specific bHLH DNA binding domain and a carboxyl-terminal WRPW (Trp-Arg-Pro-Trp) motif. These proteins act as repressors by binding to DNA sites in target gene promoters and ndt by interfering with activator proteins, indicating that these proteins are active repressors which should therefore have specific repression domains. Here we show the WRPW motif to be a functional transcriptional repression domain sufficient to confer active repression to Hairy-related proteins or a heterologous DNA-binding protein, Ga14. This motif was previously shown to be necessary for interactions with Groucho, a genetically defined corepressor for Drosophila Hairy-related proteins. Here we show that the WRPW motif is sufficient to recruit Groucho or the TLE mammalian homologs to target gene promoters. We also show that Groucho and TLE proteins actively repress transcription when directly hound to a target gene promoter and identify a novel, highly conserved transcriptional repression domain in these proteins. These results directly demonstrate that Groucho family proteins are active transcriptional corepressors for Hairy-related proteins and are recruited by the 4-amino acid protein-protein interaction domain, WRPW.

关键词： .transcriptional repression repressors activator motif bHLH protein-protein HES acts Enhancer Groucho WRPW basic helix-loop-helix interaction domain Transcription Repression Hairy-related proteins

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Transient expression of the basic helix-loop-helix protein NSCL-2 in the mouse cerebellum during postnatal development

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MOLECULAR BRAIN RESEARCH 1996年第1期36卷 174-178页

作者： Haire, MF Chiaramello, A COLORADO STATE UNIV DEPT BIOCHEM & MOLEC BIOL FT COLLINS CO 80523 USA COLORADO STATE UNIV PROGRAM NEURONAL GROWTH & DEV FT COLLINS CO 80523 USA

The spatio-temporal expression of the basic helix-loop-helix transcription factor NSCL-2 was analyzed in the postnatal development of the murine brain by in situ hybridization. We found that NSCL-2 is transiently expressed in the cerebellum. NSCL-2 was found exclusively in the premigratory zone of the external granule layer where postmitotic neurons undergo initial stages of neuronal differentiation. NSCL-2 expression was not detected in mature neurons. This pattern of expression suggests that NSCL-2 is critical for the onset of neuronal differentiation, but not for the maintenance of the differentiated state.

关键词： basic helix-loop-helix transcription factor neuronal differentiation in situ hybridization gene expression cerebellum

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Expression of basic helix-loop-helix transcription factors in explant hematopoietic progenitors

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JOURNAL OF CELLULAR BIOCHEMISTRY 1996年第3期61卷 478-488页

作者： Quesenberry, PJ Iscove, NN Cooper, C Brady, G Newburger, PE Stein, GS Stein, JS Reddy, GPV PearsonWhite, S UNIV MASSACHUSETTS MED CTRDEPT MED PEDIAT & CELL BIOLWORCESTERMA 01605 UNIV VIRGINIA HLTH SCI CTRDEPT MEDCHARLOTTESVILLEVA 22908 UNIV VIRGINIA HLTH SCI CTRDEPT PEDIATCHARLOTTESVILLEVA 22908 UNIV VIRGINIA HLTH SCI CTRDEPT MICROBIOLCHARLOTTESVILLEVA 22908 ONTARIO CANC INST TORONTOON M4X 1K9CANADA

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 Id-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. (C) 199

关键词： basic helix-loop-helix interleukin-1 interleukin-3 granulocyte-macrophage colony-stimulating factor progenitor transcription factor c-kit ligand

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Role of the PAS domain in regulation of dimerization and DNA binding specificity of the dioxin receptor

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MOLECULAR AND CELLULAR BIOLOGY 1998年第7期18卷 4079-4088页

作者： Pongratz, I Antonsson, C Whitelaw, ML Poellinger, L Karolinska Inst Dept Cell & Mol Biol S-17177 Stockholm Sweden

The dioxin receptor is a ligand-regulated transcription factor that mediates signal transduction by dioxin and related environmental pollutants. The receptor belongs to the basic helix-loop-helix (bHLH)-Per-Arnt-Sim (PAS) family of factors, which, in addition to the bHLH motif, contain a PAS region of homology. Upon activation, the dioxin receptor dimerizes with the bHLH-PAS factor Arnt, enabling the receptor to recognize xenobiotic response elements in the vicinity of target genes. We have studied the role of the PAS domain in dimerization and DNA binding specificity of the dioxin receptor and Arnt by monitoring the abilities of the individual bHLH domains and different bHLH-PAS fragments to dimerize and bind DNA in vitro and recognize target genes in vivo. The minimal bHLH domain of the dioxin receptor formed homodimeric complexes, heterodimerized with full-length Amt, and together with Arnt was sufficient for recognition of target DNA in vitro and in vivo. In a similar fashion, only the bHLH domain of Amt was necessary for DNA binding specificity in the presence of the dioxin receptor bHLH domain. Moreover, the bHLH domain of the dioxin receptor displayed a broad dimerization potential, as manifested by complex formation with, e.g., the unrelated bHLH-Zip transcription factor USP. In contrast, a construct spanning the dioxin receptor bHLH domain and an N-terminal portion of the PAS domain failed to form homodimers and was capable of dimerizing only with Amt. Thus, the PAS domain is essential to confer dimerization specificity of the dioxin receptor.

关键词： .DNA binding recognize dimerization basic helix-loop-helix dioxin bHLH domain Poellinger PAS Domain Dimerize bHLH motif factor Arnt bHLH-PAS fragments

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The aryl hydrocarbon receptor: A comparative perspective

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COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY C-TOXICOLOGY & PHARMACOLOGY 1998年第1-3期121卷 23-53页

作者： Hahn, ME Woods Hole Oceanog Inst Dept Biol Woods Hole MA 02543 USA

The aryl hydrocarbon receptor (Ah receptor or AHR) is a ligand-activated transcription factor involved in the regulation of several genes, including those for xenobiotic-metabolizing enzymes such as cytochrome P450 1A and 1B forms. Ligands for the AHR include a variety of aromatic hydrocarbons, including the chlorinated dioxins and related halogenated aromatic hydrocarbons whose toxicity occurs through activation of the AHR. The AHR and its dimerization partner ARNT are members of the emerging bHLH-PAS family of transcriptional regulatory proteins. In this review, our current understanding of the AHR signal transduction pathway in non-mammalian and other non-traditional species is summarized, with an emphasis on similarities and differences in comparison to the AHR pathway in rodents and humans. Evidence and prospects for the presence of a functional AHR in early vertebrates and invertebrates are also examined. An overview of the bHLH-PAS family is presented in relation to the diversity of bHLH-PAS proteins and the functional and evolutionary relationships of the AHR and ARNT to the other members of this family. Finally, some of the most promising directions for future research on the comparative biochemistry and molecular biology of the AHR and ARNT are discussed. (C) 1998 Elsevier Science Inc. All rights reserved.

关键词： dioxin aryl hydrocarbon receptor Ah receptor cytochrome P450 1A1 evolution ARNT basic helix-loop-helix PAS domain

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Restricted expression of E2A protein in primary human tissues correlates with proliferation and differentiation

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AMERICAN JOURNAL OF PATHOLOGY 1998年第1期153卷 165-173页

作者： Rutherford, MN LeBrun, DP Queens Univ Dept Pathol Richardson Lab Kingston ON K7L 3N6 Canada

E2A is a basic helix-loop-helix (bHLH) transcription factor required for B cell lymphopoiesis and implicated in myogenesis and the regulation of insulin expression. As E2A is expressed widely in tissues, tissue-specific downstream effects are thought to result primarily from dimerization with other bHLH proteins. To investigate the degree to which regulation of E2A protein abundance may serve to regulate E2A function, expression of E2A was evaluated using immunohistochemistry on histological sections of primary human tissues. Somewhat surprisingly, nuclear staining for E2A was restricted in all tissues examined, often to a small subpopulation of cells. In some tissues, such as adult liver, expression was absent or Limited to rare infiltrating lymphocytes. E2A-expressing cells were most abundant in lymphoid tissues. In tonsil, lymph node, and spleen, expression appeared most abundant and prevalent among rapidly proliferating centroblasts of the germinal center dark zone. Scattered E2A-expressing thymocytes were more numerous in the thymic cortex than medulla. In developing skeletal muscle, E2A was detectable in striated myotubes but not in more primitive mononucleated progenitors or mature muscle. Differential E2A expression was also noted in proliferating periventricular neuroepithelial cells in the developing brain. These results suggest that regulation of EA abundance complements protein-protein interactions in modulating E2A function.

关键词： .staining primary human restricted basic helix-loop-helix proliferation and differentiation bHLH proteins

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Animal models for dysmorphology

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CURRENT OPINION IN GENETICS & DEVELOPMENT 1998年第3期8卷 293-297页

作者： Winter, RM Inst Child Hlth Dept Clin Genet London WC1N 1EH England

Areas where studies of animal models have been vital to the understanding of human malformation syndromes include the dissection of complex genetic mechanisms such as imprinting, the creation of animal models of known... 详细信息

关键词： bHLH basic helix-loop-helix Igf2 insulin-like growth factor-2 iv inversus viscerum lrd left/right dynein UPD uniparental disomy

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Molecular cloning of the human HAND2 gene

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BIOCHIMICA ET BIOPHYSICA ACTA-GENE STRUCTURE AND EXPRESSION 1998年第3期1443卷 393-399页

作者： Russell, MW Kemp, P Wang, LH Brody, LC Izumo, S Univ Michigan Dept Pediat & Commun Dis Ann Arbor MI 48109 USA Univ Cambridge Dept Biochem Cambridge CB2 1QW England NIH Natl Human Genome Res Inst Bethesda MD 20892 USA Beth Israel Deaconess Med Ctr Div Cardiovasc Boston MA 02215 USA Harvard Univ Sch Med Dept Med Boston MA 02215 USA

We have cloned and characterized the coding sequence of the human HAND2 basic helix-loop-helix transcription factor. The amino acid sequence includes an amino-terminal polyalanine repeat which is precisely conserved in the rat HAND2 gene. Northern analysis indicates that the HAND2 transcript is 2.3 kb in length and strongly expressed in the human heart. (C) 1998 Elsevier Science B.V. All rights reserved.

关键词： HAND2 cDNA sequence cardiac myocyte basic helix-loop-helix transcription factor chromosomal localization

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