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Abundant expression of Dec1/stra13/sharp2 in colon carcinoma: its antagonizing role in serum deprivation-induced apoptosis and selective inhibition of procaspase activation

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BIOCHEMICAL JOURNAL 2002年第P2期367卷 413-422页

作者： Li, YX Zhang, H Xie, MX Hu, MW Ge, SJ Yang, DF Wan, YS Yan, BF Univ Rhode Isl Dept Biomed Sci Kingston RI 02881 USA Providence Coll Dept Biol Providence RI 02908 USA

The basic helix-loop-helix (bHLH) proteins are intimately associated with developmental events such as cell differentiation and lineage commitment. The HLH domain in the bHLH motif is responsible for dimerization, whereas the basic region mediates DNA binding. Based on sequence alignment and domain analysis, differentially expressed in chondrocytes/stimulated with retinoic acid/split and hairy-related proteins (DEC/STRA/SHARPs) represent a new class of bHLH proteins. The present study describes the functional characterization of DEC1. Subtractive experiments and blotting analyses demonstrated that DEC1 was highly expressed in colon carcinomas, but not in the adjacent normal tissues. Several cell cycle blockers markedly induced DEC1 expression. Stable transfectants with a tetracycline-inducible construct demonstrated that DEC1 caused proliferation inhibition, antagonized serum deprivation-induced apoptosis and selectively inhibited the activation of procaspases. These activities were highly correlated with the abundance of tetracycline-induced DEC1. Stable transfectants expressing a mutant DEC1 (lacking the DNA-binding domain) exhibited neither proliferation inhibition nor apoptotic antagonism, which suggests that DNA binding is required for these actions. Enzymic assays and immunoblotting analyses demonstrated that induction of DEC1 by tetracycline significantly decreased the activation of procaspases 3, 7 and 9 but not procaspase 8. The selective suppression on the activation of procaspases 3, 7 and 9 over procaspase 8 suggests that DEC1-mediated anti-apoptosis is achieved by blocking apoptotic pathways initiated via the mitochondria. The results functionally distinguish DEC1 from other bHLH proteins and directly link this factor to oncogenesis.

关键词： basic helix-loop-helix proliferation inhibition transcription factor

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A Twist in fate: evolutionary comparison of Twist structure and function

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GENE 2002年第1-2期287卷 11-22页

作者： Castanon, I Baylies, MK Mem Sloan Kettering Canc Ctr Sloan Kettering Inst Program Mol Biol New York NY 10021 USA

The general requirement to induce mesoderm and allocate cells into different mesodermal tissues such as body muscle or heart is common in many animal embryos. Since the discovery of the twist gene, there has been great progress toward unraveling the molecular mechanisms that control mesoderm specification and differentiation. Twist was first identified in Drosophila as a gene crucial for proper gastrulation and mesoderm formation. In the fly embryo, Twist continues to play additional roles, allocating mesodermal cells into the body wall muscle fate and patterning a subset of these muscles. Twist is also required for proper differentiation of the adult musculature. Twist homologues have been identified in a great variety of organisms, which span the phylogenetic tree. These organisms include other invertebrates such as jellyfish, nematode, leech and lancelet as well as vertebrates such as frog, chick, fish, mouse and human. The Twist family shares both homology in structure across the basic helix-loop-helix domain and in expression during mesoderm and muscle development in most species. Here we review the current state of knowledge of the Twist family and consider how Twist functions during development. Moreover, we highlight experimental evidence that shows common themes that Twist employs during specification and patterning of the mesoderm among evolutionarily distant organisms. Conserved principles and the molecular mechanisms underlying them are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： mesoderm muscle basic helix-loop-helix dimers

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NGF-dependent and tissue-specific transcription of vgf is regulated by a CREB-p300 and bHLH factor interaction

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FEBS LETTERS 2002年第1-2期510卷 50-56页

作者： Mandolesi, G Gargano, S Pennuto, M Illi, B Molfetta, R Soucek, L Mosca, L Levi, A Jucker, R Nasi, S Univ Roma La Sapienza CNR Ctr Acidi Nucl Dipartimento Genet & Biol Mol I-00185 Rome Italy CNR Ist Neurobiol I-00156 Rome Italy

Neurotrophins support neuronal survival, development, and plasticity through processes requiring gene expression. We studied how vgf target gene transcription is mediated by a critical promoter region containing E-box, CCAAT and cAMP response element (CRE) sites. The p300 acetylase was present in two distinct protein complexes bound to this region. One complex, containing HEB (ubiquitous basic helix-loop-helix (bHLH)), bound the promoter in non-neuronal cells and was involved in repressing vgf expression. Neurotrophin-dependent transcription was mediated by the second complex, specific for neuronal cells, which included CRE binding protein and MASH1 (neuro-specific bHLH), bound the CCAAT motif, and was target of neurotrophin signalling. The interaction, mediated by p300, of different transcription factors may add specificity to the neurotrophin response. (C) 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.

关键词： neurotrophin Vgf transcription basic helix-loop-helix cAMP response element binding protein p300

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The proneural genes NEUROD1 and NEUROD2 are expressed during human trophoblast invasion

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MECHANISMS OF DEVELOPMENT 2002年第1期113卷 85-90页

作者： Westerman, BA Poutsma, A Maruyama, K Schrijnemakers, HFJ van Wijk, IJ Oudejans, CBM Free Univ Amsterdam Ctr Med Mol Biol Lab Dept Clin Chem NL-1081 HV Amsterdam Netherlands Saitama Med Sch Dept Pharmacol Moroyama Saitama 3500495 Japan Free Univ Amsterdam Ctr Med Dept Mol Pathol NL-1081 HV Amsterdam Netherlands

During early human pregnancy, extravillous trophoblast cells invade the maternal tissue of the uterus in a way similar to invasion by cancer cells. However, the process of trophoblast invasion is regulated in a time and place restricted way, in contrast to cancer invasion. We screened first trimester placental tissue enriched by extravillous invasive trophoblasts for the expression of proneural basic helix-loop-helix (bHLH) transcription factors, which are important controllers of cell fate. Surprisingly, the presence of NEUROD1. NEUROD2 and ATH2 transcripts was found by reverse transcriptase polymerase chain reaction (RT-PCR) analysis in first trimester placentabed. Of these genes, the proneural genes NEUROD1 and NEUROD2 are expressed in different subsets of invasive trophoblasts. NEUROD1 expression is found in interstitial and endovascular invasive cells, while NEUROD2 expression is observed mainly in endovascular invasive cells, respectively. These data suggest that in addition to the involvement of proneural genes in neuron, neurendocrine and pancreas differentiation, these genes are involved in trophoblast differentation during progression of invasion. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

关键词： extravillous trophoblast basic helix-loop-helix transcription factor endovascular invasion proneural NEUROD1 NEUROD2 ATH2 ASCL2

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Gradient of E2A activity in B-cell development

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MOLECULAR AND CELLULAR BIOLOGY 2002年第3期22卷 886-900页

作者： Herblot, S Aplan, PD Hoang, T Clin Res Inst Montreal Montreal PQ H2W 1R7 Canada Univ Montreal Dept Pharmacol Montreal PQ H3C 3J7 Canada Univ Montreal Dept Biochem Montreal PQ H3C 3J7 Canada Univ Montreal Program Mol Biol Montreal PQ H3C 3J7 Canada Natl Canc Inst Dept Genet Med Branch Div Clin Sci Gaithersburg MD 20877 USA

The E2A locus is a frequent target of chromosomal translocations in B-cell acute lymphoblastic leukemia (B-ALL). E2A encodes two products, E12 and E47, that are part of the basic helix-loop-helix (bHLH) family of transcription factors and are central in B lineage differentiation. E2A haplo-insufficiency hinders progression through three major checkpoints in B-cell development: commitment into the B lineage, at the pro-B to pre-B transition, and in the induction of immunoglobulin M (IgM) expression required for a functional BCR. These observations underscore the importance of E2A gene dosage in B-cell development. Here we show that a higher proportion of pro-B cells in E2A(+/-) mice is in the cell cycle compared to that in wild-type littermates. This increase correlates with lower P21(waf/cip1) levels, indicating that E2A has an antiproliferative function in B-cell progenitors. Ectopic expression in the B lineage of SCL/Tall, a tissue-specific bHLH factor that inhibits E2A function, blocks commitment into the B lineage without affecting progression through later stages of differentiation. Furthermore, ectopic SCL expression exacerbates E2A haplo-insufficiency in B-cell differentiation, indicating that SCL genetically interacts with E2A. Taken together, these observations provide evidence for a gradient of E2A activity that increases from the pre-pro-B to the pre-B stage and suggest a model in which low levels of E2A (as in pro-B cells) are sufficient to control cell growth, while high levels (in pre-B cells) are required for cell differentiation. The antiproliferative function of E2A further suggests that in B-ALL associated with t(1;19) and t(17;19), the disruption of one E2A allele contributes to leukemogenesis, in addition to other anomalies induced by E2A fusion proteins.

关键词： .gradient lineage observations bHLH cell development commitment basic helix-loop-helix Montr Herblot

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Retrovirus-mediated gene transfer to retinal explants

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METHODS 2002年第4期28卷 387-395页

作者： Hatakeyama, J Kageyama, R Kyoto Univ Inst Virus Res Kyoto 6068507 Japan

Neural retina can be isolated from mouse embryos and maintained in culture for 2-3 weeks. In such retinal explant cultures, precursor cells differentiate into neurons and glial cells and form three cellular layers, mimicking well the normal development. This explant culture system is suitable for genetic manipulation, such as retrovirus-mediated gene transfer. Retroviral vectors can efficiently transfer genes into retinal precursors, and the copy of the viral genome is precisely transmitted to the progeny of infected cells. Thus, this is an excellent method to change stably the phenotypes of dividing cells. It has been shown that retroviruses carrying transcription factor genes efficiently change the fates of infected cells. Bicistronic expression by retroviral vectors is useful to test the effects of various combinations of many transcription factors. With this method, the transcriptional codes for retinal cell type specification are now being elucidated. Thus, retrovirus-mediated gene transfer to the retinal explant culture system offers a powerful and unique tool to analyze the molecular mechanism of neural development. (C) 2002 Elsevier Science (USA). All rights reserved.

关键词： basic helix-loop-helix bicistronic expression green fluorescent protein homeodomain retinal explant retrovirus transcriptional code

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Characterization of interactions between transcription factors and a regulatory region spanning nt-320 to-281 of the HIV-1 LTR in T-lymphoid and non-T-lymphoid cells

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JOURNAL OF BIOMEDICAL SCIENCE 2002年第1期9卷 68-81页

作者： Pereira, LA Churchill, MJ Elefanty, AG Gouskos, T Lambert, PF Ramsay, RG Deacon, NJ Macfarlane Burnet Ctr Med Res AIDS Mol Biol Unit Natl Ctr HIV Virol Res Fairfield Vic 3078 Australia Univ Med Ctr Physiol Chem Lab Utrecht Netherlands Univ Med Ctr Ctr Biomed Genet Utrecht Netherlands Royal Melbourne Hosp Walter & Eliza Hall Inst Med Res Div Canc & Haematol Parkville Vic 3050 Australia Flinders Univ S Australia Sch Med Bedford Pk SA 5042 Australia Peter MacCallum Canc Inst Melbourne Vic Australia

HIV-1 gene expression is regulated by the interplay of transcription factors with multiple binding motifs present within the U3, R and U5 regions of the long terminal repeat (LTR). Here we report novel DNA binding complexes (termed 9a, 9b and 9c) between nuclear proteins from T-lymphoid and non-T-lymphoid cells and a region of the U3 LTR between nucleotides (nts) -320 to -281 in the HIV strain HXB2. Complex 9b bound a motif predicted to bind E-box or c-Myb proteins and a partially overlapping dyad symmetrical motif, and included basic helix-loop-helix proteins (E12, E47 or ITF-1) but surprisingly not c-Myb. Complex 9c, which bound to a pair of GATA sites, included GATA-3 and GATA-4 in Jurkat and MT-2 cells, respectively. We also demonstrate that the c-Myb/E-box and GATA sites form a bipartite motif required for the formation of complex 9a. Transient transfection experiments with T cells revealed that in the context of a minichromosome assembled full-length LTR, mutation of region -320 to -281 increased basal and PMA-stimulated LTR activity. These findings suggest that this region is an important component of the HIV-1 LTR required for response to different cellular transcription factors. Copyright (C) 2002 National Science Council, ROC and S. Karger AG, Basel.

关键词： HIV-1 LTR promoter c-Myb basic helix-loop-helix GATA factor

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The functional specificity of NeuroD is defined by a single amino acid residue (N11) in the basic domain

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FEBS LETTERS 2002年第1-3期520卷 139-144页

作者： Wang, XK Korzh, V Gong, ZY Natl Univ Singapore Dept Biol Sci Singapore 117543 Singapore Natl Univ Singapore Inst Mol Agrobiol Singapore 117543 Singapore

In zebrafish, the basic helix-loop-helix (bHLH) gene neuroD specifies distinct neurons in the spinal cord. A preliminary experiment indicated that a related bHLH gene, ndr1a, normally expressed only in the olfactory organ in late embryos, also functions as neuroD to induce ectopic formation of spinal cord neurons in early embryos after introduction of its mRNA into early embryos. To define the functional specificity of these bHLH proteins, several mutant forms with selected point mutations in the basic domain were constructed and tested for inducing sensory neurons in the spinal cord. Our data indicate that the functional specificity of NeuroD to define sensory neurons is mainly due to a single residue (asparagine 11) in its basic domain. (C) 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.

关键词： zebrafish basic helix-loop-helix basic domain neurogenesis neuron isl-1

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Non-overlapping expression of Olig3 and Olig2 in the embryonic neural tube

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MECHANISMS OF DEVELOPMENT 2002年第2期113卷 169-174页

作者： Takebayashi, H Ohtsuki, T Uchida, T Kawamoto, S Okubo, K Ikenaka, K Takeichi, M Chisaka, O Nabeshima, Y Kyoto Univ Grad Sch Med Dept Pathol & Tumor Biol Sakyo Ku Kyoto 6068501 Japan Kyoto Univ Fac Sci Sakyo Ku Kyoto 6068502 Japan Kyoto Univ Grad Sch Biostudies Sakyo Ku Kyoto 6068502 Japan Osaka Univ Inst Mol & Cellular Biol Suita Osaka 5650871 Japan Natl Inst Physiol Sci Lab Neural Informat Okazaki Aichi 4448585 Japan

Olig family is a novel sub-family of basic helix-loop-helix transcription factors recently identified. Olig 1 and Olig2 were first reported to promote oligodendrocyte differentiation. and later Olig2 was reported to be involved in motorneuron specification as well. Olig3 was isolated as a third member of Olig family. but its precise expression pattern is poorly understood. Here, we describe detailed Olig3 expression analyses in the neural tube of embryonic mice. Olig3 was first detected in the dorsal neural tube from the hindbrain/hindbrain boundary to the spinal cord. In E11.5 spinal cord. Olig3 was transiently expressed in the lateral margin of the subventricular zone as three ventral clusters at the level of the p3, p2 and p0 domains, as well as in the dolorsal neural tube. Olig3 was co-expresed with Nkx2.2 in the lateral margin of the p3 domain. In forebrain Olig3 was expressed in the dorsal thalamus while Olig2 was complementarily expressed in the ventral thalamus with an adjacent boundary at E12.5. Olig3 is specifically and transiently expressed in different types of progenitors of embryonic central nervous system and then disappears in the course of development. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

关键词： basic helix-loop-helix transcription factor Olig3 Olig2 thalamus rhombic lip cerebellar neuroepithelium D1 interneuron nkx2.2 pax6 pax7 jagged1 math1 mash1 MBH1 barhl1 neurogenin2 mouse zebrafish medaka

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The EBF/Olf/Collier family of transcription factors:: Regulators of differentiation in cells originating from all three embryonal germ layers

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MOLECULAR AND CELLULAR BIOLOGY 2002年第24期22卷 8389-8397页

作者： Liberg, D Sigvardsson, M Åkerblad, P Lund Univ Dept Stem Cell Biol SE-22184 Lund Sweden AstraZeneca R&D Molndal Dept Mol Biol SE-43183 Molndal Sweden

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关键词： .controlling melanogaster interact dimerization bHLH basic helix-loop-helix evolutionarily

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