1
|
Carrothers S, Trevisan R, Jayasundara N, Pelletier N, Weeks E, Meyer JN, Di Giulio R, Weinhouse C. An epigenetic memory at the CYP1A gene in cancer-resistant, pollution-adapted killifish. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.14.607951. [PMID: 39185187 PMCID: PMC11343184 DOI: 10.1101/2024.08.14.607951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
Human exposure to polycyclic aromatic hydrocarbons (PAH) is a significant and growing public health problem. Frequent, high dose exposures are likely to increase due to a warming climate and increased frequency of large-scale wildfires. Here, we characterize an epigenetic memory at the cytochrome P450 1A ( CYP1A ) gene in a population of wild Fundulus heteroclitus that has adapted to chronic, extreme PAH pollution. In wild-type fish, CYP1A is highly induced by PAH. In PAH-tolerant fish, CYP1A induction is blunted. Since CYP1A metabolically activates PAH, this memory protects these fish from PAH-mediated cancer. However, PAH-tolerant fish reared in clean water recover CYP1A inducibility, indicating that blunted induction is a non-genetic memory of prior exposure. To explore this possibility, we bred depurated wild fish from PAH-sensitive and -tolerant populations, manually fertilized exposure-naïve embryos, and challenged them with PAH. We observed epigenetic control of the reversible memory of generational PAH stress in F 1 PAH-tolerant embryos. Specifically, we observed a bivalent domain in the CYP1A promoter enhancer comprising both activating and repressive histone post-translational modifications. Activating modifications, relative to repressive ones, showed greater increases in response to PAH in sensitive embryos, relative to tolerant, consistent with greater gene activation. Also, PAH-tolerant adult fish showed persistent induction of CYP1A long after exposure cessation, which is consistent with defective CYP1A shutoff and recovery to baseline. Since CYP1A expression is inversely correlated with cancer risk, these results indicate that PAH-tolerant fish have epigenetic protection against PAH-induced cancer in early life that degrades in response to continuous gene activation. Significance Epigenetic memory, or the inheritance across cell division within an organism or across generations, of environmental exposure response is a compelling phenomenon with limited understanding of mechanism. Here, we characterized an epigenetic memory at the CYP1A gene in pollution-adapted Fundulus heteroclitus . We found that the CYP1A promoter enhancer contains a bivalent domain, comprising both active and repressive histone modifications, that shows reduced function correlating with reduced gene induction by its pollutant activator. In early life, this memory protects fish against pollution-induced cancer. However, this reduced function carries a cost; adult fish show defective transcriptional recovery of CYP1A , which increases cancer risk later in life. These results provide an initial mechanism for a model epigenetic memory and highlight potential costs.
Collapse
|
2
|
Herholz M, Cepeda E, Baumann L, Kukat A, Hermeling J, Maciej S, Szczepanowska K, Pavlenko V, Frommolt P, Trifunovic A. KLF-1 orchestrates a xenobiotic detoxification program essential for longevity of mitochondrial mutants. Nat Commun 2019; 10:3323. [PMID: 31346165 PMCID: PMC6658563 DOI: 10.1038/s41467-019-11275-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 06/28/2019] [Indexed: 12/29/2022] Open
Abstract
Most manipulations that extend lifespan also increase resistance to various stress factors and environmental cues in a range of animals from yeast to mammals. However, the underlying molecular mechanisms regulating stress resistance during aging are still largely unknown. Here we identify Krüppel-like factor 1 (KLF-1) as a mediator of a cytoprotective response that dictates longevity induced by reduced mitochondrial function. A redox-regulated KLF-1 activation and transfer to the nucleus coincides with the peak of somatic mitochondrial biogenesis that occurs around a transition from larval stage L3 to D1. We further show that KLF-1 activates genes involved in the xenobiotic detoxification programme and identified cytochrome P450 oxidases, the KLF-1 main effectors, as longevity-assurance factors of mitochondrial mutants. Collectively, these findings underline the importance of the xenobiotic detoxification in the mitohormetic, longevity assurance pathway and identify KLF-1 as a central factor in orchestrating this response.
Collapse
Affiliation(s)
- Marija Herholz
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Estela Cepeda
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Linda Baumann
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Alexandra Kukat
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Johannes Hermeling
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Sarah Maciej
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Karolina Szczepanowska
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Victor Pavlenko
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Peter Frommolt
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Aleksandra Trifunovic
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany. .,Center for Molecular Medicine Cologne (CMMC), D-50931, Cologne, Germany.
| |
Collapse
|
3
|
Hoffmann M, Mager WH, Scholte BJ, Civil A, Planta RJ. Analysis of the promoter of the cytochrome P-450 2B2 gene in the rat. Gene Expr 2018; 2:353-63. [PMID: 1335316 PMCID: PMC6057372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
About 3 kb of the promoter region of the gene encoding cytochrome P-450 2B2 (CYP2B2) in the rat were sequenced and searched for potential cis-acting elements. Apart from putative binding sites for (liver-specific) protein factors, a region showing homology with the LINE 1 retrotransposon element was also found. Three proximal promoter fragments, encompassing nucleotides -579 to -372, -372 to -211, and -211 to +1, respectively, were shown to contain binding sites for multiple protein factors by bandshift analyses. The strongest protein-binding element, designated BRE (basic regulatory element), occurs between -103 to -66. Its structure is very similar to a negative control element in the murine cmyc promoter and displays a composite feature having a tandemly repeated sequence homology with the BTE (basic transcription element; Yanagida et al., 1990) separated by a CCAAA-box. The use of a deletion series of this template in in vitro transcription assays, provided evidence that the BRE serves as a major cis-acting element in the (regulated) transcription activation of the CYP2B2 gene.
Collapse
Affiliation(s)
- M Hoffmann
- Department of Biochemistry and Molecular Biology, Vrije Universiteit, Amsterdam, The Netherlands
| | | | | | | | | |
Collapse
|
4
|
Sławek S, Szmyt K, Fularz M, Dziudzia J, Boruczkowski M, Sikora J, Kaczmarek M. Pluripotency transcription factors in lung cancer-a review. Tumour Biol 2015; 37:4241-9. [PMID: 26581906 DOI: 10.1007/s13277-015-4407-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 11/09/2015] [Indexed: 12/28/2022] Open
Abstract
Lung cancer is the leading cause of cancer-related mortality worldwide. Diagnosis of lung cancer in an early stage is still a challenge due to the asymptomatic course of early stages of the disease and the lack of a standard screening program for the population. Nowadays, learning about the mechanisms that lead to cancerogenesis in the lung is crucial for the development of new diagnostic and therapeutic strategies. Recently, many studies have proved that cancer stem cells (CSCs) are responsible for the initiation, progression, metastasis, recurrence, and even resistance of chemo- and radiotherapeutic treatment in patients with lung cancer. The expression of pluripotency transcription factors is responsible for stemness properties. In this review, we summarize the current knowledge on the role of CSCs and pluripotency transcription factors in lung carcinogenesis.
Collapse
Affiliation(s)
- Sylwia Sławek
- Department of Immunology, Chair of Clinical Immunology, Poznan University of Medical Sciences, Poznan, Poland.
| | - Krzysztof Szmyt
- Department of Immunology, Chair of Clinical Immunology, Poznan University of Medical Sciences, Poznan, Poland
| | - Maciej Fularz
- Department of Immunology, Chair of Clinical Immunology, Poznan University of Medical Sciences, Poznan, Poland
| | - Joanna Dziudzia
- Department of Immunology, Chair of Clinical Immunology, Poznan University of Medical Sciences, Poznan, Poland
| | - Maciej Boruczkowski
- Department of Immunology, Chair of Clinical Immunology, Poznan University of Medical Sciences, Poznan, Poland
| | - Jan Sikora
- Department of Immunology, Chair of Clinical Immunology, Poznan University of Medical Sciences, Poznan, Poland
| | - Mariusz Kaczmarek
- Department of Immunology, Chair of Clinical Immunology, Poznan University of Medical Sciences, Poznan, Poland
| |
Collapse
|
5
|
Tekpli X, Zienolddiny S, Skaug V, Stangeland L, Haugen A, Mollerup S. DNA methylation of the CYP1A1 enhancer is associated with smoking-induced genetic alterations in human lung. Int J Cancer 2012; 131:1509-16. [PMID: 22213191 DOI: 10.1002/ijc.27421] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 12/15/2011] [Indexed: 11/08/2022]
Abstract
CYP1A1 (cytochrome P4501A1) catalyze the conversion of polycyclic aromatic hydrocarbons into reactive metabolites, which may induce DNA damage. We hypothesized that DNA methylation of the CYP1A1 enhancer could be involved in inter-individual differences in mRNA levels of CYP1A1 or affect the smoking-induced DNA damage in human lung. Using DNA bisulfite conversion and pyrosequencing, we show that DNA methylation of the CYP1A1 enhancer is affected by smoking. In adjacent histologically normal lung from lung cancer patients (n = 120), low levels of DNA methylation of the CYP1A1 enhancer were related to high levels of smoking-induced hydrophobic DNA adduct (p < 0.03), and to the presence of TP53 or K-ras mutations in the corresponding lung tumors (p < 0.03). We found an inverse correlation between DNA methylation of the CYP1A1 enhancer and mRNA levels in vivo (Spearman r = -0.54; p < 0.0001). Thus, in lung tumor tissues, the CYP1A1 enhancer hypermethylation was associated with lower mRNA levels compared to adjacent histologically normal tissue (p < 0.0001). In vitro, using a panel of cultured human lung cells, we found hypermethylation of the CYP1A1 enhancer in cancer cell lines and an inverse correlation between DNA methylation and mRNA levels (Spearman r = -0.53; p = 0.003). Altogether, our results indicated that low levels of DNA methylation of the CYP1A1 enhancer in histologically normal human lung were associated with high CYP1A1 mRNA levels and with smoking-induced genetic alterations; thus, it may play a role in the initiation of lung carcinogenesis.
Collapse
Affiliation(s)
- Xavier Tekpli
- Section for Toxicology, Department of Biological and Chemical Working Environment, National Institute of Occupational Health, Oslo, Norway
| | | | | | | | | | | |
Collapse
|
6
|
Ovesen JL, Schnekenburger M, Puga A. Aryl hydrocarbon receptor ligands of widely different toxic equivalency factors induce similar histone marks in target gene chromatin. Toxicol Sci 2011; 121:123-31. [PMID: 21292640 DOI: 10.1093/toxsci/kfr032] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Posttranslational histone modifications are a critical regulatory mechanism of gene transcription. Previous studies from our laboratory have shown that contingent on binding to its cognate promoter motifs in the Cyp1a1 gene, activation of the aryl hydrocarbon receptor (AHR) by benzo[a]pyrene (BaP) treatment induces histone modifications in the Cyp1a1 promoter that are required for activation of gene transcription. Here, we have studied different AHR ligands, including polychlorinated biphenyls (PCBs) of different toxic equivalency factors (TEF), to determine whether changes in histone modifications are linked to different levels of Cyp1a1 expression or dependent on AHR-ligand affinity. We find that all ligands lead to the same pattern of histone modifications in a relationship that parallels the strength of their AHR-ligand affinity. Thus, whereas PCB126 (TEF 0.1), 3-methylcholanthrene, β-naphthoflavone, and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) initiate a pattern of histone marks similar to those induced by BaP, PCB77 (TEF 0.0001) causes a lower level of change in the same marks and requires a longer activation time than PCB126, BaP, or TCDD. In contrast, the non-dioxin-like PCB153 recruits AHR to the Cyp1a1 enhancer causing a displacement of enhancer-associated histone H3 but does not cause the other observed histone mark changes nor does it induce transcription. These results indicate that AHR recruitment to the promoter is not sufficient to induce the histone modifications needed to activate gene expression and show that there is a good correlation between the regulatory chromatin changes associated with ligand-induced AHR target gene transcription and the resultant toxicity of the ligand.
Collapse
Affiliation(s)
- Jerald L Ovesen
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati Medical Center, Cincinnati, Ohio 45267-0056, USA
| | | | | |
Collapse
|
7
|
Fujii-Kuriyama Y, Kawajiri K. Molecular mechanisms of the physiological functions of the aryl hydrocarbon (dioxin) receptor, a multifunctional regulator that senses and responds to environmental stimuli. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2010; 86:40-53. [PMID: 20075607 PMCID: PMC3417568 DOI: 10.2183/pjab.86.40] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 11/09/2009] [Indexed: 05/28/2023]
Abstract
The aryl hydrocarbon receptor (AhR) was originally identified as a ligand-activated transcription factor that is involved in the induction of xenobiotic-metabolizing Cytochrome P4501A1 (CYP1A1). For several decades, AhR has been studied in relation to toxicology and pharmacology. With recent discoveries on novel AhR functions, AhR research has expanded into multiple aspects of physiology, such as reproduction, innate immunity and tumor suppression. In this review, we summarize and discuss recent progress in mechanistic and functional studies on AhR with particular emphasis on physiological processes.
Collapse
Affiliation(s)
- Yoshiaki Fujii-Kuriyama
- Institute of Molecular and Cellular Biosciences, University of Tokyo, 5-18-7 Honkomagame, Bunkyo-ku, Tokyo, Japan.
| | | |
Collapse
|
8
|
Monostory K, Pascussi JM, Kóbori L, Dvorak Z. Hormonal regulation of CYP1A expression. Drug Metab Rev 2009; 41:547-72. [DOI: 10.1080/03602530903112284] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
9
|
Involvement of CREM in CYP1A1 induction through ligand-independent activation pathway of aryl hydrocarbon receptor in HepG2 cells. Arch Biochem Biophys 2008; 478:26-35. [DOI: 10.1016/j.abb.2008.07.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 07/07/2008] [Accepted: 07/24/2008] [Indexed: 11/21/2022]
|
10
|
Schnekenburger M, Peng L, Puga A. HDAC1 bound to the Cyp1a1 promoter blocks histone acetylation associated with Ah receptor-mediated trans-activation. ACTA ACUST UNITED AC 2007; 1769:569-78. [PMID: 17707923 PMCID: PMC2083643 DOI: 10.1016/j.bbaexp.2007.07.002] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Revised: 07/12/2007] [Accepted: 07/12/2007] [Indexed: 11/24/2022]
Abstract
Metabolic bioactivation of polycyclic aromatic hydrocarbons, such as the environmental procarcinogen benzo[a]pyrene, is catalyzed by a cytochrome P450 monooxygenase encoded by the substrate-inducible Cyp1a1 gene. Cyp1a1 induction requires trans-activation by the heterodimeric transcriptional complex formed by the liganded Ah receptor (AHR) and its partner, ARNT. Previously, we showed that constitutively bound HDAC1 dissociates from Cyp1a1 promoter chromatin after ligand-mediated induction, concomitantly with the recruitment of AHR/ARNT complexes and p300. Here, we investigated the hypothesis that HDAC1 binding maintains the Cyp1a1 gene in a silenced state in uninduced cells. We find that Cyp1a1 induction by the AHR/ARNT is associated with modification of specific chromatin marks, including hyperacetylation of histone H3K14 and H4K16, trimethylation of histone H3K4, and phosphorylation of H3S10. HDAC1 and DNMT1 form complexes on the Cyp1a1 promoter of uninduced cells but HDAC1 inhibition alone is not sufficient to induce Cyp1a1 expression, although it allows for the hyperacetylation of H3K14 and H4K16 to levels similar to those found in B[a]P-induced cells. These results show that by blocking the modification of histone marks, HDAC1 plays a central role in Cyp1a1 expression and that its removal is a necessary but not sufficient condition for Cyp1a1 induction, underscoring the requirement for a concerted series of chromatin-remodeling events to complete the initial steps of gene trans-activation by the Ah receptor.
Collapse
Affiliation(s)
| | | | - Alvaro Puga
- Corresponding author: Alvaro Puga, Department of Environmental Health, University of Cincinnati Medical Center, P.O. Box 670056. Cincinnati, OH 45267-00567, (Messenger Mail, use: 123 E. Shields St. Cincinnati, OH 45220), Phone: (513) 558-0916; FAX: (513) 558-0925, E-mail:
| |
Collapse
|
11
|
Abstract
Recent analyses revealed that Krüppel-like factors (KLFs) play important roles in both normal development and carcinogenesis. Of the 16 known KLFs, KLF4 has been shown to be involved in the regulation of proliferation, differentiation and tumorigenesis of gastrointestinal tract epithelium. Clinical, experimental and mechanistic findings indicate that KLF4 is a bona fide tumor suppressor for both gastric and colorectal cancers. In this review, we summarize how this growing area of research has formed and the challenging new frontiers for better understanding of the oncogenic potential of the KLFs.
Collapse
Affiliation(s)
- Daoyan Wei
- Department of Gastrointestinal Medical Oncology, Department of Neurosurgery and Department of Cancer Biology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
| | | | | | | |
Collapse
|
12
|
Sogawa K, Numayama-Tsuruta K, Takahashi T, Matsushita N, Miura C, Nikawa JI, Gotoh O, Kikuchi Y, Fujii-Kuriyama Y. A novel induction mechanism of the rat CYP1A2 gene mediated by Ah receptor-Arnt heterodimer. Biochem Biophys Res Commun 2004; 318:746-55. [PMID: 15144902 DOI: 10.1016/j.bbrc.2004.04.090] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2004] [Indexed: 11/21/2022]
Abstract
We have identified an enhancer responsible for induction by 3-methylcholanthrene in the upstream region of the CYP1A2 gene. The enhancer does not contain the invariant core sequence of XREs that are binding sites for the Ah receptor (AhR) and Arnt heterodimer. The enhancer did not show any inducible expression in Hepa-1-derived cell lines, C4 and C12, deficient of Arnt and AhR, respectively. On the other hand, bacterially expressed AhR-Arnt heterodimer could not bind to the enhancer. Mutational analysis of the enhancer revealed that a repeated sequence separated by six nucleotides is important for expression. A factor binding specifically to the enhancer was found by using gel shift assays. Bacterially expressed AhR-Arnt heterodimer interacted with the factor. A dominant negative mutant of the AhR to XRE activated the enhancer. Collectively, these results demonstrate that a novel induction mechanism is present in which the AhR-Arnt heterodimer functions as a coactivator.
Collapse
Affiliation(s)
- Kazuhiro Sogawa
- Department of Biomolecular Science, Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan.
| | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Chrisman HR, Tindall DJ. Identification and characterization of a consensus DNA binding element for the zinc finger transcription factor TIEG/EGRalpha. DNA Cell Biol 2003; 22:187-99. [PMID: 12804117 DOI: 10.1089/104454903321655819] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
TGFbeta-Inducible Early Gene (TIEG) and the alternatively-transcribed Early Growth Response Gene alpha (EGRalpha) share a Cys(2)His(2) three-zinc finger region with high homology to Sp1 within its zinc finger region. Three-zinc finger transcription factors bind to GC-rich sequences, with small variations in consensus sequence between subfamilies. In this work, a consensus sequence was identified for TIEG/EGRalpha by expressing and purifying the zinc finger region of the protein, and using this to select a binding site from a random oligonucleotide library by iterative cycles of nitrocellulose filter binding and PCR. A fusion of the TIEG/EGRalpha with the VP16 activation domain supported transcription from this site when cloned in front of a heterologous promoter. Mutational analysis of the binding site identified a GT-rich core (5'-GGTGTG-3') that was necessary for binding, with mutations outside of this region causing only a small to moderate decrease in binding.
Collapse
Affiliation(s)
- Holly R Chrisman
- Department of Urology Research, Mayo Clinic/Foundation, Rochester, Minnesota 55905, USA
| | | |
Collapse
|
14
|
Hoopfer ED, Huang L, Denver RJ. Basic transcription element binding protein is a thyroid hormone-regulated transcription factor expressed during metamorphosis in Xenopus laevis. Dev Growth Differ 2002; 44:365-81. [PMID: 12392570 DOI: 10.1046/j.1440-169x.2002.00650.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Basic transcription element binding protein (BTEB) is a member of the Krüppel family of zinc finger transcription factors. It has been shown that BTEB plays a role in promoting neuronal process formation during postembryonic development. In the present study, the biochemical properties, transactivation function, and the developmental and hormone-regulated expression of BTEB in Xenopus laevis (xBTEB) are described. xBTEB binds the GC-rich basic transcription element (BTE) with high affinity and functions as a transcriptional activator on promoters containing multiple or single GC boxes. xBTEB mRNA levels increase in the tadpole brain, intestine and tail during metamorphosis, and are correlated with tissue-specific morphological and biochemical transformations. xBTEB mRNA expression can be induced precociously in premetamorphic tadpole tissues by treatment with thyroid hormone. In situ hybridization histochemistry showed that thyroid hormone upregulates xBTEB mRNA throughout the brain of premetamorphic tadpoles, with the highest expression found in the subventricular zones of the telencephalon, diencephalon, optic tectum, cerebellum and spinal cord. xBTEB protein parallels changes in its mRNA, and it was found that xBTEB is not expressed in mitotic cells in the developing brain, but is expressed just distal to the proliferative zone, supporting the hypothesis that this protein plays a role in neural cell differentiation.
Collapse
Affiliation(s)
- Eric D Hoopfer
- 3065C Natural Science Building, Department of Molecular, Cellular and Developmental Biology, The University of Michigan, Ann Arbor, MI 48109-1048, USA
| | | | | |
Collapse
|
15
|
Saito T, Takahashi Y, Hashimoto H, Kamataki T. Novel transcriptional regulation of the human CYP3A7 gene by Sp1 and Sp3 through nuclear factor kappa B-like element. J Biol Chem 2001; 276:38010-22. [PMID: 11495920 DOI: 10.1074/jbc.m106130200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human CYP3A7 and CYP3A4 are expressed in fetal and adult livers, respectively, although the 5'-flanking regions of the two genes show 90% homology. The purpose of this study was to clarify the mechanism(s) responsible for the transcriptional regulation of the CYP3A7 gene in human hepatoma HepG2 cells that showed fetal phenotypes. Transfection studies using a series of the CYP3A7 or CYP3A4 promoter-luciferase chimeric genes identified a nuclear factor kappaB (NF-kappaB)-like element between nucleotides -2326 and -2297 that conferred the transcriptional activation of the CYP3A7 gene. A 1-base pair mismatch within the corresponding region of the CYP3A4 gene was sufficient for a differential enhancer activity. A gel shift assay using nuclear extracts from HepG2 cells showed that Sp1 and Sp3 bound to the NF-kappaB-like element of the CYP3A7 but not CYP3A4 gene. Specific activation of the CYP3A7 promoter by Sp1 and Sp3 was confirmed by a co-transfection of the p3A7NF-kappaB or p3A4NF-kappaB reporter gene with Sp1 or Sp3 expression plasmid into Drosophila cells, which lacked endogenous Sp family. Additionally, introduction of mutations into binding sites for hepatocyte nuclear factor 3beta, upstream stimulatory factor 1, and a basic transcription element in the proximal promoter attenuated luciferase activity to 20% of the level seen with the intact CYP3A7 promoter. Thus, we conclude that the expression of the CYP3A7 gene in HepG2 cells is cooperatively regulated by Sp1, Sp3, hepatocyte nuclear factor 3beta, and upstream stimulatory factor 1.
Collapse
Affiliation(s)
- T Saito
- Laboratory of Drug Metabolism, Graduate School of Pharmaceutical Sciences, Hokkaido University, N12W6, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
| | | | | | | |
Collapse
|
16
|
Kaczynski J, Zhang JS, Ellenrieder V, Conley A, Duenes T, Kester H, van Der Burg B, Urrutia R. The Sp1-like protein BTEB3 inhibits transcription via the basic transcription element box by interacting with mSin3A and HDAC-1 co-repressors and competing with Sp1. J Biol Chem 2001; 276:36749-56. [PMID: 11477107 DOI: 10.1074/jbc.m105831200] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sp1-like proteins are characterized by three conserved C-terminal zinc finger motifs that bind GC-rich sequences found in promoters of numerous genes essential for mammalian cell homeostasis. These proteins behave as transcriptional activators or repressors. Although significant information has been reported on the molecular mechanisms by which Sp1-like activators function, relatively little is known about mechanisms for repressor proteins. Here we report the functional characterization of BTEB3, a ubiquitously expressed Sp1-like transcriptional repressor. GAL4 assays show that the N terminus of BTEB3 contains regions that can act as direct repressor domains. Immunoprecipitation assays reveal that BTEB3 interacts with the co-repressor mSin3A and the histone deacetylase protein HDAC-1. Gel shift assays demonstrate that BTEB3 specifically binds the BTE site, a well characterized GC-rich DNA element, with an affinity similar to that of Sp1. Reporter and gel shift assays in Chinese hamster ovary cells show that BTEB3 can also mediate repression by competing with Sp1 for BTE binding. Thus, the characterization of this protein expands the repertoire of BTEB-like members of the Sp1 family involved in transcriptional repression. Furthermore, our results suggest a mechanism of repression for BTEB3 involving direct repression by the N terminus via interaction with mSin3A and HDAC-1 and competition with Sp1 via the DNA-binding domain.
Collapse
Affiliation(s)
- J Kaczynski
- Gastroenterology Research Unit, Mayo Clinic, Rochester, Minnesota 55901, USA
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Abstract
Cytochrome P4501A1 is a substrate-inducible microsomal enzyme that oxygenates polycyclic aromatic hydrocarbons, such as the carcinogen benzo(a)pyrene, as the initial step in their metabolic processing to water-soluble derivatives. Enzyme induction reflects increased transcription of the cognate CYP1A1 gene. The environmental toxicant 2,3,7,8-tetrachlorodibenzo-p-dioxin is the most potent known cytochrome P4501A1 inducer. Two regulatory proteins, the aromatic (aryl) hydrocarbon receptor (AhR) and the AhR nuclear translocator (Arnt), mediate induction. AhR and Arnt are prototypical members of the basic helix-loop-helix/Per-Arnt-Sim class of transcription factors. Mechanistic analyses of cytochrome P4501A1 induction provide insights into ligand-dependent mammalian gene expression, basic helix-loop-helix/Per-Arnt-Sim protein function, and dioxin action; such studies also impact public health issues concerned with molecular epidemiology, carcinogenesis, and risk assessment.
Collapse
Affiliation(s)
- J P Whitlock
- Department of Molecular Pharmacology, Stanford University School of Medicine, California 94305-5332, USA.
| |
Collapse
|
18
|
Peng HM, Coon MJ. Promoter function and the role of cytokines in the transcriptional regulation of rabbit CYP2E1 and CYP2E2. Arch Biochem Biophys 2000; 382:129-37. [PMID: 11051106 DOI: 10.1006/abbi.2000.2001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rabbit CYP2E1 and CYP2E2 show considerable similarity in the 5' flanking region, but a 32-base-pair element (32-BPE) that is repeated in 2E1 is present only as a single inexact copy in 2E2. In the present investigation, footprinting disclosed two specific binding sites for liver nuclear proteins, and the DNase I sensitivity profiles of the two genes were found to be different. Several positive and negative regulatory elements were identified by transfection with a series of constructs of upstream CYP2E sequences fused to the luciferase gene. Both genes have an HNF-1 consensus motif with one nucleotide mismatch, which affects binding affinity and promoter activity. Investigation of DNA-protein interactions revealed that Sp1 and NFkappaB bind exclusively to the 32-BPE of 2E1 and 2E2, respectively, suggesting a possible regulatory role for the 32-BPE. Interleukin-1alpha (IL-1alpha) gave rise to a 2.5-fold increase in the promoter activity of 2E1 in HepG2 cells, and the IL-1alpha-mediated induction of reporter gene expression was almost completely prevented when the 32-BPE was deleted. Increased DNA binding and Sp1 protein content as a result of IL-1alpha treatment, as well as cotransfection experiments with pPacSp1, suggest that Sp1 is a transcription activator for the induction of 2E1 by IL-1alpha in HepG2 cells.
Collapse
Affiliation(s)
- H M Peng
- Department of Biological Chemistry, Medical School, The University of Michigan, Ann Arbor 48109, USA.
| | | |
Collapse
|
19
|
Kanamura S, Watanabe J. Cell biology of cytochrome P-450 in the liver. INTERNATIONAL REVIEW OF CYTOLOGY 2000; 198:109-52. [PMID: 10804462 DOI: 10.1016/s0074-7696(00)98004-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cytochromes P-450 (P-450) are members of a multigene superfamily of hemoproteins consisting the microsomal monooxygenase system with NADPH P-450 reductase (reductase) and/or reducing equivalents. Expression of many P-450 isoforms in hepatocytes is shown to be regulated at the level of transcription through interaction between cis-acting elements in the genes and DNA-binding (transacting) factors. Some isoforms of the CYP1A, 2B, 2E, and 3A subfamilies are regulated at the posttranscriptional level. For the topology of P-450 and reductase molecules in ER membrane of hepatocytes, models from stopped flow analysis and electron spin resonance are proposed. The densities of total P-450 and reductase molecules are revealed to be high enough to support the cluster model, suggesting that about ten P-450 molecules form an aggregate and surround one reductase molecule, and therefore the two enzymes form large micelles. ER proliferation after PB administration, which had been correlated with increase in P-450 level, is shown to be probably independent of the increase in P-450 level. There are considerable discrepancies among results reported on sublobular expression of various P-450 isoforms. Causes of the discrepancies are likely to be differences in experimental conditions of histochemical detection carried out and/or in species, strain, and/or sex.
Collapse
Affiliation(s)
- S Kanamura
- Department of Anatomy, Kansai Medical University, Osaka, Japan
| | | |
Collapse
|
20
|
Okino ST, Whitlock JP. The aromatic hydrocarbon receptor, transcription, and endocrine aspects of dioxin action. VITAMINS AND HORMONES 2000; 59:241-64. [PMID: 10714242 DOI: 10.1016/s0083-6729(00)59009-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The widespread and persistent environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin elicits adaptive and adverse biological responses by inducing changes in gene transcription. Some of dioxin's effects reflect disruption of endocrine homeostasis. The aromatic hydrocarbon receptor protein, together with its heterodimerization partner, the aromatic hydrocarbon receptor nuclear translocator protein, mediates dioxin action. There are notable similarities between the mechanism of dioxin action and the mechanisms of steroid/retinoid/thyroid hormone action. Studies of dioxin action may provide insights into the regulation of hormone-responsive genes and endocrine physiology.
Collapse
Affiliation(s)
- S T Okino
- Department of Molecular Pharmacology, Stanford University School of Medicine, California 94305, USA
| | | |
Collapse
|
21
|
Affiliation(s)
- R Kato
- Department of Pharmacology, School of Medicine, Keio University, Tokyo, Japan
| | | |
Collapse
|
22
|
Dang DT, Pevsner J, Yang VW. The biology of the mammalian Krüppel-like family of transcription factors. Int J Biochem Cell Biol 2000; 32:1103-21. [PMID: 11137451 PMCID: PMC2754176 DOI: 10.1016/s1357-2725(00)00059-5] [Citation(s) in RCA: 358] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Recent advances in molecular cloning have led to the identification of a large number of mammalian zinc finger-containing transcription factors that exhibit homology to the Drosophila melanogaster protein, Krüppel. Although the amino acid sequences in the zinc finger domains of these Krüppel-like factors (KLFs) are closely related to one another, the regions outside the zinc fingers of the proteins are usually unique. KLFs display seemingly different and broad biological properties with each functioning as an activator of transcription, a repressor or both. This review article provides a current phylogenetic classification of the identified KLFs to date. More importantly, the currently known biological activities of the KLFs in regulating transcription, cell proliferation, differentiation and development are summarized and compared. Further characterization of this interesting protein family should provide additional insights into the their respective regulatory role in various important biological processes.
Collapse
Affiliation(s)
- Duyen T. Dang
- Department of Medicine, The Johns Hopkins University School of Medicine, 918 Ross Research Building, 720 Rutland Avenue, Baltimore, MD 21205, USA
| | - Jonathan Pevsner
- Department of Neurology, Kennedy Krieger Research Institute, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Vincent W. Yang
- Department of Medicine, The Johns Hopkins University School of Medicine, 918 Ross Research Building, 720 Rutland Avenue, Baltimore, MD 21205, USA
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Corresponding author. Tel.: +1-410-955-9691; fax: +1-410-955-9677. E-mail address: (V.W. Yang)
| |
Collapse
|
23
|
Wilson CL, Safe S. Mechanisms of ligand-induced aryl hydrocarbon receptor-mediated biochemical and toxic responses. Toxicol Pathol 1998; 26:657-71. [PMID: 9789953 DOI: 10.1177/019262339802600510] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The ubiquitous environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) is a member of a broad group of halogenated aromatic hydrocarbons (HAHs) that is known to induce a wide range of toxic and biochemical responses in laboratory animals and humans. The effects of HAH exposure are mediated by binding to the cytosolic aryl hydrocarbon receptor (AhR), which is expressed in a tissue- and cell type-specific manner. The AhR is a ligand-activated transcription factor belonging to the basic helix-loop-helix/Per-AhR-Arnt-Sim (bHLH/PAS) superfamily of proteins. The mechanism of induction of gene transcription by TCDD involves ligand recognition and binding by the AhR, nuclear translocation, and dimerization with the AhR cofactor, AhR nuclear translocator (Arnt). The nuclear heterodimer interacts with cognate xenobiotic responsive elements (XREs) in promoter/enhancer regions of multiple Ah-responsive genes. Subsequent changes in chromatin structure and/or interaction of the AhR complex with the basal transcriptional machinery play a significant role in AhR-mediated gene expression. Although Arnt is a necessary component of a functional nuclear AhR complex, this protein also forms transcriptionally active heterodimers with other bHLH/PAS factors, including those involved in the transcriptional response to hypoxia. Arnt is ubiquitously expressed in mammalian systems, and results from transgenic mouse studies suggest that this protein plays a vital role in early mammalian embryonic development. Similar experiments suggest that the AhR may be involved in development of various organ systems. Thus, molecular mechanistic studies of TCDD action have contributed significantly to an improved understanding of the role of at least 2 bHLH/PAS proteins, as well as organ- and tissue-specific biochemical and toxic responses to this class of environmental toxins.
Collapse
Affiliation(s)
- C L Wilson
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station 77843-4466, USA
| | | |
Collapse
|
24
|
Xu C, Pasco DS. Suppression of CYP1A1 transcription by H2O2 is mediated by xenobiotic-response element. Arch Biochem Biophys 1998; 356:142-50. [PMID: 9705204 DOI: 10.1006/abbi.1998.0770] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have previously demonstrated that H2O2 downregulates CYP1A1 and CYP1A2 transcription in isolated rat hepatocytes (C. W. Barker, et al., 1994, J. Biol. Chem. 269, 3985-3990). In the present study, induction of chloramphenicol acetyltransferase (CAT) expression driven by 3.1 kb of rat CYP1A1 upstream regulatory sequences was suppressed by 56% in Hepa-1 cells treated with H2O2. Similarly, H2O2 inhibited CAT expression from vectors containing two copies of either xenobiotic-response element (XRE) 1 or XRE2. H2O2 did not inhibit basal CAT expression in cells that were not treated with the inducer beta-napthoflavone. Electrophoretic mobility shift assays demonstrated that the suppression of XRE-dependent transcription by H2O2 was not due to changes in nuclear aryl hydrocarbon (Ah) receptor DNA binding activity. Several types of experiments indicated that modulation of XRE enhancer strength by various means could modify H2O2-dependent suppression of CAT expression. Conditions that increased the transactivation potential of the Ah receptor (increase in XRE copy number or shortening of the distance between XREs and the minimal CYP1A1 promoter) attenuated the action of H2O2, while conditions that reduced XRE-mediated transactivation potential (decrease in XRE copy number, increase of the distance between the XRE and the promoter, or reduction of the number of bound Ah receptors by lowering the concentration of inducer) potentiated the inhibitory action of H2O2.
Collapse
Affiliation(s)
- C Xu
- Molecular Biology Laboratory, Maharishi University of Management, Fairfield, Iowa, 52557, USA
| | | |
Collapse
|
25
|
Regulation of Cytochrome P450 Gene Transcription by Phenobarbital. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1998. [DOI: 10.1016/s0079-6603(08)60824-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
26
|
Geng J, Strobel HW. Expression and induction of cytochrome P-450 1A1 and P-450 2D subfamily in the rat glioma C6 cell line. Brain Res 1997; 774:11-9. [PMID: 9452186 DOI: 10.1016/s0006-8993(97)81681-2] [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: 02/06/2023]
Abstract
The cytochrome P-450 (P-450) monooxygenase system can catalyze the oxidation of a wide variety of endogenous and exogenous compounds, including steroid hormones, fatty acids, drugs and pollutants. The functions of this system are as diverse as the substrates. Though this enzyme system has the highest level of activity in the liver, it is present in other tissues, including brain. In this study, we have established the rat glioma C6 cell line as an in vitro model system to examine the expression and induction of P-450 1A1 and the P-450 2D subfamily. Rat glioma C6 cells were treated with P-450 inducers phenobarbital (PB) or benzo[a]anthracene (BA). The presence of P-450 1A1 and 2D1-5 was detected by reverse transcription followed by polymerase chain reaction (RT-PCR) and confirmed by restriction enzyme digestion. The induction of P-450 1A1 and 2D1-5 was quantified using competitive PCR. Although P-450 2D1-5 do not seem to be affected by PB or BA treatment, tenfold induction of P-450 1A1 mRNA after BA treatment was detected. Western blot analysis of microsomal preparations of glioma C6 cells demonstrated the presence of P-450 1A1 at the protein level. ELISAs showed that BA induces P-450 1A1 proteins 7.3-fold. These experiments provide further evidence that the rat glioma C6 cell line contains an active cytochrome P-450 monooxygenase system which can be induced by P-450 inducers. In summary, we believe the presence of the cytochrome P-450 monooxygenase system in glial cells of the brain may be important in chemotherapy and carcinogenesis of brain tumors.
Collapse
Affiliation(s)
- J Geng
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School, Houston 77225, USA
| | | |
Collapse
|
27
|
Wo YY, Stewart J, Greenlee WF. Functional analysis of the promoter for the human CYP1B1 gene. J Biol Chem 1997; 272:26702-7. [PMID: 9334254 DOI: 10.1074/jbc.272.42.26702] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Our laboratory has cloned the cDNA (Sutter, T. R., Tang, Y. M., Hayes, C. L., Wo, Y.-Y. P., Jabs, E. W., Li, X., Yin, H., Cody, C. W. , and Greenlee, W. F. (1994) J. Biol. Chem. 269, 13092-13099) and gene (Tang, Y. M., Wo, Y.-Y. P., Jabs, E. W., Stewart, J. C., Sutter, T. R., and Greenlee, W. F. (1996) J. Biol. Chem. 271, 28324-28330) for human CYP1B1, a new member of the cytochrome P450 superfamily. Here, we report on the mapping and function of the CYP1B1 promoter. The CYP1B1 promoter is fully functional, when it is uncoupled from upstream enhancer elements. Deletion analysis and site-directed mutagenesis identified four regulatory elements required for maximum promoter activity: two antisense Sp1 sites (-84 to -89 and -68 to -73), a TATA-like box (-34 to -29), and an initiator motif (-5 to +3). The initiator and the TATA-like elements are both required for basal promoter activity, with enhanced activity mediated by the two antisense Sp1 elements. The CYP1B1 initiator was demonstrated by in vitro transcription analysis to be a positioning element that maintained fidelity of transcription from a single site. Specific binding to a CYP1B1 initiator probe by human nuclear extract proteins was competed either by the highly homologous murine terminal deoxynucleotidyl transferase initiator or, to a lesser extent, by the adenovirus major late initiator. Taken together, these results indicate that the structure and function of the CYP1B1 promoter confers constitutive expression of the gene and assures fidelity of transcription initiation from a single site. The CYP1B1 promoter is distinct from the promoters of the closely related cytochrome P450s CYP1A1 and CYP1A2 and is structurally and functionally similar to the promoters of constitutively expressed genes and at least two viruses.
Collapse
Affiliation(s)
- Y Y Wo
- Department of Molecular Pharmacology and Medicinal Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
| | | | | |
Collapse
|
28
|
Itoh S, Abe Y, Kubo A, Okuda M, Shimoji M, Nakayama K, Kamataki T. Isolation of a promoter region in mouse cytochrome P450 3A (Cyp3A16) gene and its transcriptional control. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1350:155-8. [PMID: 9048885 DOI: 10.1016/s0167-4781(96)00215-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
An 11.5 kb fragment of the mouse Cyp3a16 gene containing the 5' flanking region was isolated from the lambda DASHII mouse genomic library. A part of the 5' flanking region and the first exon of Cyp3a16 gene were sequenced. S1 mapping analysis showed the presence of two transcriptional initiation sites. The first exon was completely identical to Cyp3a16 cDNA. The identity of 5' flanking sequences between Cyp3a16 and Cyp3a11 genes was about 69%. A typical TATA box and a basic transcription element (BTE) were found as seen with other CYP3A genes from various animal species Moreover, some putative transcriptional regulatory elements were also found in addition to the sequence motif seen for the formation of Z-type DNA. To examine the transcriptional activity of Cyp3a11 gene, DNA fragments in the 5'-flanking region of the gene were inserted front of the luciferase structural gene, and the constructs were transfected in primary hepatocytes. The analysis of the luciferase activity indicated that the region between -146 and -56 was necessary for the transcription of CYP3a16 gene.
Collapse
Affiliation(s)
- S Itoh
- Division of Drug Metabolism, Faculty of Pharmaceutical Sciences, Hokkaido University, Japan
| | | | | | | | | | | | | |
Collapse
|
29
|
Baudler M, Duschl J, Winkler C, Schartl M, Altschmied J. Activation of transcription of the melanoma inducing Xmrk oncogene by a GC box element. J Biol Chem 1997; 272:131-7. [PMID: 8995238 DOI: 10.1074/jbc.272.1.131] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Melanoma formation in Xiphophorus is caused by overexpression of the Xmrk gene. The promoter region of the Xmrk oncogene differs strikingly from the corresponding proto-oncogenic sequences and was acquired in the course of a nonhomologous recombination with another gene locus, D. In order to identify regulatory elements leading to the strong transcriptional activation of Xmrk in melanoma tissue and to contribute to an understanding of the role the regulatory locus R might play in suppressing the tumor phenotype in wild-type Xiphophorus, we performed functional analysis of the Xmrk oncogene promoter. Transient transfections in melanoma and nonmelanoma cells revealed the existence of a potent positive regulatory element positioned close to the transcriptional start site. Contained within this promoter segment is a GC-rich sequence identical to the binding site described for human Sp1. In vitro binding studies and biochemical characterizations demonstrated the existence of GC-binding proteins in fish that share immunological properties with members of the human Sp family of transcription factors and appear to be involved in the high transcriptional activation of the Xmrk oncogene. Since the identified cis element is functional in both melanoma and nonmelanoma cells, additional silencer elements suppressing Xmrk expression in nonpigment cells must exist, thereby suggesting a negative regulatory function for the genetically defined R locus.
Collapse
Affiliation(s)
- M Baudler
- Physiological Chemistry I, Theodor Boveri Institute for Biosciences (Biocenter), University of Würzburg, Federal Republic of Germany
| | | | | | | | | |
Collapse
|
30
|
Park Y, Kemper B. The CYP2B1 proximal promoter contains a functional C/EBP regulatory element. DNA Cell Biol 1996; 15:693-701. [PMID: 8769571 DOI: 10.1089/dna.1996.15.693] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Cytochromes P450 2B1 and 2B2 (CYP2B1 and CYP2B2) are well-known phenobarbital-inducible genes in rat liver. Potential transcriptional regulatory elements in the proximal promoter regions of rat CYP2B genes were analyzed by transfection in HepG2 hepatoma cells and by binding of nuclear proteins. Deletion of sequences from -1,400 to -110 had modest effects on promoter activity, but further deletion to -57 decreased the transcriptional activity by more than 90%, suggesting the presence of strong cis-acting elements in this region. Sequences similar to a basal transcription element (BTE) in CYP1A1 and a proposed phenobarbital responsive element (Barbie box) are present from -89 to -67. However, no protection was detected in these regions by DNase I footprinting assay. Instead, a region (FP1) from -64 to -45 was protected by liver nuclear extracts. Mutation of either the BTE or FP1 sequences of CYP2B1, or both, reduced transcriptional activity by 70-80% in HepG2 cells. FP1 was identified as a functional C/EBP site by co-transfection of C/EBP expression vectors and supershift assays with C/EBP antisera. Binding of liver nuclear proteins to sequences within the -110 to +1 region was not detectably altered by pretreatment of rats with phenobarbital.
Collapse
Affiliation(s)
- Y Park
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, 61801, USA
| | | |
Collapse
|
31
|
Kobayashi A, Sogawa K, Fujii-Kuriyama Y. Cooperative interaction between AhR.Arnt and Sp1 for the drug-inducible expression of CYP1A1 gene. J Biol Chem 1996; 271:12310-6. [PMID: 8647831 DOI: 10.1074/jbc.271.21.12310] [Citation(s) in RCA: 123] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Expression of CYP1A1 gene is regulated in a substrate-inducible manner through at least two kinds of regulatory DNA elements in addition to the TATA sequence, XRE (xenobiotic responsive element), and BTE (basic transcription element), a GC box sequence. The trans-acting factor on the XRE is a heterodimer consisting of arylhydrocarbon receptor (AhR) and AhR nuclear translocator (Arnt), while Sp1 acts as a regulatory factor on the BTE. We have investigated how these factors interact with one another to induce expression of the CYP1A1 gene. Both in vivo transfection assays using Drosophila Schneider line 2 (SL2) cells, which is devoid of endogenous Sp1, AhR, and Arnt, and in vitro transcription assays using baculovirus-expressed AhR, Arnt, and Sp1 proteins revealed that these factors enhanced synergistically expression of the reporter genes driven by a model CYP1A1 promoter, consisting of four repeated XRE sequences and a BTE sequence, in agreement with previous observation (Yanagida, A., Sogawa, K., Yasumoto, K., and Fujii-Kuriyama, Y. (1990) Mol. Cell. Biol. 10, 1470-1475). We have proved by coimmunoprecipitation assays and DNase I footprinting that both AhR and Arnt interact with the zinc finger domain of Sp1 via their basic HLH/PAS domains. When either the AhR.Arnt heterodimer of Sp1 was bound to its cognate DNA element, DNA binding of the second factor was facilitated. Survey of DNA sequences in the promoter region shows that the XRE and GC box elements are commonly found in the genes whose expressions are induced by polycyclic aromatic hydrocarbons, suggesting that the two regulatory DNA elements and their cognate trans-acting factors constitute a common mechanism for induction of a group of drug-metabolizing enzymes.
Collapse
Affiliation(s)
- A Kobayashi
- Department of Chemistry, Faculty of Science, Tohoku University, Sendai, Japan
| | | | | |
Collapse
|
32
|
Emi Y, Ikushiro S, Iyanagi T. Xenobiotic responsive element-mediated transcriptional activation in the UDP-glucuronosyltransferase family 1 gene complex. J Biol Chem 1996; 271:3952-8. [PMID: 8632018 DOI: 10.1074/jbc.271.7.3952] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We have isolated genomic DNA clones containing rat UDP-glucuronosyltransferase family 1 (UGT1) sequences and have shown drug-responsive and tissue-specific alternative expression of multiple first exons (Emi, Y., Ikushiro, S., and Iyanagi, T. (1995) J. Biochem. (Tokyo) 117, 392-399). The UGT1 locus encodes at least nine UGT1 isoforms. UGT1A1 is a major 3-methylcholanthrene (MC)-inducible form in rat liver. In this report, we have identified a cis-acting element necessary for transcriptional activation of UGT1A1 in hepatocytes. A promoter region was fused to a chloramphenicol acetyltransferase gene, and the resultant construct was transiently transfected into hepatocytes. A DNA fragment carrying 1,100 nucleotides derived from the 5'-flanking region of the UGT1A1 gene was enough for MC induction. Unidirectional deletion of this region revealed that there existed one xenobiotic responsive element (XRE), TGCGTG, between -134 and -129. When a single base substitution was introduced into the XRE, MC-induced expression of the UGT1A1 gene was completely abolished. In addition, an XRE-deleted construct failed to respond to MC. Gel mobility shift assays showed MC-inducible binding of the nuclear aromatic hydrocarbon receptor-ligand complex to this motif. Gel shift-coupled DNase I protection analyses revealed that the GCGTG-core sequence was a target site of the liganded aromatic hydrocarbon receptor. These results suggest that the XRE participates in induction of the rat UGT1A1 gene by MC.
Collapse
Affiliation(s)
- Y Emi
- Department of Life Science, Faculty of Science, Himeji Institute of Technology, Harima Science Park City, Hyogo 678-12, Japan
| | | | | |
Collapse
|
33
|
Comparative properties of the nuclear aryl hydrocarbon (Ah) receptor complex from several human cell lines. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/0926-6917(95)00017-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
34
|
Jørgensen EC, Autrup H. Effect of a negative regulatory element (NRE) on the human CYP1A1 gene expression in breast carcinoma MCF-7 and hepatoma HepG2 cells. FEBS Lett 1995; 365:101-7. [PMID: 7781760 DOI: 10.1016/0014-5793(95)00456-j] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The expression of the cytochrome P4501A1 gene, CYP1A1, is induced by e.g. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) mainly by transcriptional mechanisms. The inducers mediate their effect upon binding and activation of the aryl hydrocarbon receptor (AHR) transcription-factor complex. Utilizing chimeric CYP1A1/CAT constructs transient gene expression experiments indicate that the putative negative regulatory element (NRE) of CYP1A1 influence the relative TCDD induced CAT activity in HepG2 cells, whereas this effect was not observed in MCF-7 cells. Differences in the formation of cell-specific protein-DNA complexes were demonstrated by gel retardation assays suggesting a functional difference of NRE in these two cell lines.
Collapse
Affiliation(s)
- E C Jørgensen
- Department of Environmental and Occupational Medicine, University of Aarhus, Denmark
| | | |
Collapse
|
35
|
Gao B, Spector MS, Kunos G. The rat alpha 1B adrenergic receptor gene middle promoter contains multiple binding sites for sequence-specific proteins including a novel ubiquitous transcription factor. J Biol Chem 1995; 270:5614-9. [PMID: 7890681 DOI: 10.1074/jbc.270.10.5614] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Transcription of the rat alpha 1B adrenergic receptor (alpha 1BAR) gene in the liver is controlled by three promoters that generate three mRNAs. The middle promoter (P2), located between -432 and -813 base pairs upstream from the translation start codon and lacking a TATA box, is responsible for generating the major, 2.7-kilobase mRNA-species expressed in many tissues (Gao, B., and Kunos, G. (1994) J. Biol. Chem. 269, 15762-15767). DNase I footprinting using rat liver nuclear extracts identified three protected regions in P2: footprint I (-432 to -452), footprint II (-490 to -540), and footprint III (-609 to -690). Putative response elements in footprints I and III were not analyzed except the AP2 binding site in footprint III, which could be protected by purified AP2 protein. Footprint II contains four sites corresponding to half of the NF-I consensus sequence, but DNA mobility shift assays indicate that this footprint binds two proteins distinct from NF-I: a ubiquitous CP1-related factor and another novel factor, termed alpha-Adrenergic Receptor Transcription Factor (alpha ARTF), which binds to two separate sites in this region. The alpha ARTF is widely distributed, with the highest amounts found in brain, followed by liver, kidney, lung, and spleen, but no detectable activity in heart. Deletions of alpha ARTF binding sites nearly abolished P2 promoter activity, which suggests that the alpha ARTF is essential for the transcription of the alpha 1BAR gene in most tissues.
Collapse
Affiliation(s)
- B Gao
- Department of Pharmacology, Virginia Commonwealth University School of Medicine, Richmond 23298
| | | | | |
Collapse
|
36
|
Safe SH. Modulation of gene expression and endocrine response pathways by 2,3,7,8-tetrachlorodibenzo-p-dioxin and related compounds. Pharmacol Ther 1995; 67:247-81. [PMID: 7494865 DOI: 10.1016/0163-7258(95)00017-b] [Citation(s) in RCA: 221] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The aryl hydrocarbon (Ah) receptor binds several different structural classes of chemicals, including halogenated aromatics, typified by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), polynuclear aromatic and heteropolynuclear aromatic hydrocarbons. TCDD induces expression of several genes including CYP1A1, and molecular biology studies show that the Ah receptor acts as a nuclear ligand-induced transcription factor that interacts with xenobiotic or dioxin responsive elements located in 5'-flanking regions of responsive genes. TCDD also elicits diverse toxic effects, modulates endocrine pathways and inhibits a broad spectrum of estrogen (17 beta-estradiol)-induced responses in rodents and human breast cancer cell lines. Molecular biology studies show that TCDD inhibited 17 beta-estradiol-induced cathepsin D gene expression by targeted interaction of the nuclear Ah receptor with imperfect dioxin responsive elements strategically located within the estrogen receptor-Sp1 enhancer sequence of this gene.
Collapse
Affiliation(s)
- S H Safe
- Texas A&M University, College Station 77843-4466, USA
| |
Collapse
|
37
|
Miyata A, Yokoyama C, Ihara H, Bandoh S, Takeda O, Takahashi E, Tanabe T. Characterization of the human gene (TBXAS1) encoding thromboxane synthase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 224:273-9. [PMID: 7925341 DOI: 10.1111/j.1432-1033.1994.00273.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The gene encoding human thromboxane synthase (TBXAS1) was isolated from a human EMBL3 genomic library using human platelet thromboxane synthase cDNA as a probe. Nucleotide sequencing revealed that the human thromboxane synthase gene spans more than 75 kb and consists of 13 exons and 12 introns, of which the splice donor and acceptor sites conform to the GT/AG rule. The exon-intron boundaries of the thromboxane synthase gene were similar to those of the human cytochrome P450 nifedipine oxidase gene (CYP3A4) except for introns 9 and 10, although the primary sequences of these enzymes exhibited 35.8% identity each other. The 1.2-kb of the 5'-flanking region sequence contained potential binding sites for several transcription factors (AP-1, AP-2, GATA-1, CCAAT box, xenobiotic-response element, PEA-3, LF-A1, myb, basic transcription element and cAMP-response element). Primer-extension analysis indicated the multiple transcription-start sites, and the major start site was identified as an adenine residue located 142 bases upstream of the translation-initiation site. However, neither a typical TATA box nor a typical CAAT box is found within the 100-b upstream of the translation-initiation site. Southern-blot analysis revealed the presence of one copy of the thromboxane synthase gene per haploid genome. Furthermore, a fluorescence in situ hybridization study revealed that the human gene for thromboxane synthase is localized to band q33-q34 of the long arm of chromosome 7. A tissue-distribution study demonstrated that thromboxane synthase mRNA is widely expressed in human tissues and is particularly abundant in peripheral blood leukocyte, spleen, lung and liver. The low but significant levels of mRNA were observed in kidney, placenta and thymus.
Collapse
Affiliation(s)
- A Miyata
- Department of Pharmacology, National Cardiovascular Center Research Institute, Osaka, Japan
| | | | | | | | | | | | | |
Collapse
|
38
|
Jean A, Reiss A, Desrochers M, Dubois S, Trottier E, Trottier Y, Wirtanen L, Adesnik M, Waxman DJ, Anderson A. Rat liver cytochrome P450 2B3: structure of the CYP2B3 gene and immunological identification of a constitutive P450 2B3-like protein in rat liver. DNA Cell Biol 1994; 13:781-92. [PMID: 8068203 DOI: 10.1089/dna.1994.13.781] [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: 01/28/2023] Open
Abstract
The cytochrome P450 2B subfamily in the rat contains an estimated eight to eleven members at the genomic level. Synthesis in the liver of the prototypic forms P450 2B1 and P450 2B2 is dramatically induced by phenobarbital. The 1.9-kb mRNA for P450 2B3, a third member of the P450 2B subfamily, is constitutively present in rat liver but is not inducible by phenobarbital. We have now cloned and sequenced exonic sequences corresponding to the entire 2B3 mRNA and determined their exon-intron structure, which is identical to that of CYP2B1/CYP2B2 and other CYP2B genes. A putative CYP2B3 transcription start site was identified and CYP2B3 5'- and 3'-flanking sequences were compared to those of CYP2B1 and CYP2B2. CYP2B3, like CYP2B1 and CYP2B2, has a modified TATA box preceding the transcription start site and lacks the canonical polyadenylation signal preceding the poly(A) site. A 2B3 expression vector, pMT2-2B3, directed the synthesis in COS-1 cells of an approximately 50-kD protein detectable on Western blots with a polyclonal antibody and with one of four monoclonal antibodies raised against 2B1 but not with a polyclonal antibody raised against P450 PB6. The 2B3 protein migrated with a slightly higher electrophoretic mobility than 2B1 and comigrated with a protein detected by anti-2B1 antibodies in liver microsomes from untreated rats. The results indicate that a 2B3-like protein is present in rat liver and that it is distinct from P450 PB6 and other known constitutive rat hepatic P450s.
Collapse
Affiliation(s)
- A Jean
- Centre de recherche en cancérologie de l'Université Laval, L'Hôtel-Dieu de Québec, Canada
| | | | | | | | | | | | | | | | | | | |
Collapse
|
39
|
Shephard EA, Forrest LA, Shervington A, Fernandez LM, Ciaramella G, Phillips IR. Interaction of proteins with a cytochrome P450 2B2 gene promoter: identification of two DNA sequences that bind proteins that are enriched or activated in response to phenobarbital. DNA Cell Biol 1994; 13:793-804. [PMID: 8068204 DOI: 10.1089/dna.1994.13.793] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Cytochromes P450 (CYPs) are of central importance in the metabolism of foreign hydrophobic compounds. Members of the CYP2B subfamily are inducible at the transcriptional level by the barbiturate, phenobarbital. Owing to the lack of a suitable phenobarbital-responsive cell line, very little is known regarding the mechanisms by which phenobarbital induces the expression of these genes. We report the use of gel retardation and DNase I footprinting to investigate the presence of regulatory protein binding sites within a CYP2B2 gene promoter. Two DNA sequences, located between -183 to -199 and -31 to -72, have been identified that bind rat liver nuclear proteins that are enriched or activated in vivo by phenobarbital. Gel retardation competition experiments demonstrated that the two sequences bound different proteins. In vitro transcription competition experiments demonstrated that the sequences and the proteins with which they interact are involved in regulating CYP2B2 gene transcription. These two DNA sequences and their cognate binding proteins may play a role in the induction of CYP2B2 gene expression in response to phenobarbital.
Collapse
Affiliation(s)
- E A Shephard
- Department of Biochemistry and Molecular Biology, University College London, UK
| | | | | | | | | | | |
Collapse
|
40
|
Yoshida Y, Aoyama Y. The P450 superfamily: A group of versatile hemoproteins contributing to the oxidation of various small molecules. Stem Cells 1994. [DOI: 10.1002/stem.5530120710] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
41
|
Nakayama K, Suwa Y, Mizukami Y, Sogawa K, Fujii-Kuriyama Y. Cloning and sequencing of a novel rat cytochrome P450 2B-encoding gene. Gene X 1993; 136:333-6. [PMID: 8294026 DOI: 10.1016/0378-1119(93)90490-t] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
A novel rat P450 2B gene encoding cytochrome P450 2B15 was cloned and sequenced. The gene is separated into nine exons by eight introns. This gene structure is very similar to those of P450 2B1 and 2B2, except that the coding sequences of the gene are longer in the first and ninth exons than those of the P450 2B1 and 2B2 genes.
Collapse
Affiliation(s)
- K Nakayama
- Department of Chemistry, Faculty of Science, Tohoku University, Sendai, Japan
| | | | | | | | | |
Collapse
|
42
|
Hashimoto H, Toide K, Kitamura R, Fujita M, Tagawa S, Itoh S, Kamataki T. Gene structure of CYP3A4, an adult-specific form of cytochrome P450 in human livers, and its transcriptional control. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 218:585-95. [PMID: 8269949 DOI: 10.1111/j.1432-1033.1993.tb18412.x] [Citation(s) in RCA: 146] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
CYP3 A4 is the adult-specific form of cytochrome P450 in human livers [Komori, M., Nishio, K., Kitada, M., Shiramatsu, K., Muroya, K., Soma, M., Nagashima, K. & Kamataki, T. (1990) Biochemistry 29, 4430-4433]. The sequences of three genomic clones for CYP3A4 were analyzed for all exons, exon-intron junctions and the 5'-flanking region from the major transcription site to nucleotide position -1105, and compared with those of the CYP3A7 gene, a fetal-specific form of cytochrome P450 in humans. The results showed that the identity of 5'-flanking sequences between CYP3A4 and CYP3A7 genes was 91%, and that each 5'-flanking region had characteristic sequences termed as NFSE (P450NF-specific element) and HFLaSE (P450HFLa specific element), respectively. A basic transcription element (BTE) also lay in the 5'-flanking region of the CYP3A4 gene as seen in many CYP genes [Yanagida, A., Sogawa, K., Yasumoto, K. & Fujii-Kuriyama, Y. (1990) Mol. Cell. Biol. 10, 1470-1475]. The BTE binding factor (BTEB) was present in both adult and fetal human livers. To examine the transcriptional activity of the CYP3A4 gene, DNA fragments in the 5'-flanking region of the gene were inserted in front of the simian virus 40 promoter and the chloramphenicol acetyltransferase structural gene, and the constructs were transfected in HepG2 cells. The analysis of the chloramphenicol acetyltransferase activity indicated that (a) specific element(s) which could bind with a factor(s) in livers was present in the 5'-flanking region of the CYP3A4 gene to show the transcriptional activity.
Collapse
Affiliation(s)
- H Hashimoto
- Division of Drug Metabolism, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | | | | | | | | | | | | |
Collapse
|
43
|
Imataka H, Mizuno A, Fujii-Kuriyama Y, Hayami M. Activation of the human immunodeficiency virus type 1 long terminal repeat by BTEB, a GC box-binding transcription factor. AIDS Res Hum Retroviruses 1993; 9:825-31. [PMID: 8257632 DOI: 10.1089/aid.1993.9.825] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
BTEB, a GC box-binding transcription factor, was tested for its ability to activate the human immunodeficiency virus type 1 long terminal repeat (HIV-1 LTR). An electrophoretic mobility shift assay demonstrated specific binding of BTEB to GC boxes of the HIV-1 LTR. When a BTEB expression vector was cotransfected into A3.01 cells with a fusion gene of HIV-1 LTR and chloramphenicol acetyltransferase (CAT) structural gene, the CAT activity was increased. This increase was accompanied by an increase in the content of CAT mRNA. Transcriptional activity of the HIV-1 LTR, stimulated by Tat, was further enhanced by the expression of BTEB. BTEB also activated the LTR activity in cooperation with phorbol 12-myristate 13-acetate. Northern blot analysis showed that various T cell and macrophage/monocyte cell lines expressed the BTEB mRNA to a level comparable with that of Sp1, another GC box-binding transcription factor. These results suggest that BTEB, like Sp1, is involved in transcriptional activation of the HIV-1 LTR.
Collapse
Affiliation(s)
- H Imataka
- Institute for Virus Research, Kyoto University, Japan
| | | | | | | |
Collapse
|
44
|
Hoekman MF, Rientjes JM, Twisk J, Planta RJ, Princen HM, Mager WH. Transcriptional regulation of the gene encoding cholesterol 7 alpha-hydroxylase in the rat. Gene 1993; 130:217-23. [PMID: 8359688 DOI: 10.1016/0378-1119(93)90422-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The cytochrome P450 enzyme, cholesterol 7 alpha-hydroxylase (CYP7A), catalyses the first and rate-limiting step in the conversion of cholesterol to bile acids. Expression of the CYP7A gene is under complex physiological control, encompassing amongst others a feedback down-regulation by bile acids. Using the CYP7A cDNA of the rat as a probe, we isolated a rat genomic clone containing the 5' part of the gene, including approximately 3.6 kb of upstream sequences. Sequence analysis revealed the presence of several putative regulatory elements. Transient expression analyses of transfected primary hepatocytes demonstrated that the major transcription-activating region is located in the proximal 145 nucleotide (nt). Upon addition of taurocholate to the culture, a significant reduction of the transcriptional activity was observed, suggesting the presence of a bile acid-responsive element in the proximal region of the CYP7A promoter. In addition, evidence was obtained for the presence of a thyroxine-responsive site further upstream. After addition of taurocholate, steady-state CYP7A mRNA levels, as judged by Northern analysis of hepatocyte RNA, are eightfold reduced. On the other hand, the transcriptional activity of CYP7A, as shown both in CAT assays and run-on experiments, revealed only a threefold decrease. These experiments suggest that both transcriptional control and regulation of CYP7A mRNA stability play an important part in the feedback regulation of CYP7A activity in the rat.
Collapse
Affiliation(s)
- M F Hoekman
- Department of Biochemistry and Molecular Biology, Vrije Universiteit, Amsterdam, Netherlands
| | | | | | | | | | | |
Collapse
|
45
|
Watanabe N, Kitazume M, Fujisawa J, Yoshida M, Fujii-Kuriyama Y. A novel cAMP-dependent regulatory region including a sequence like the cAMP-responsive element, far upstream of the human CYP21A2 gene. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 214:521-31. [PMID: 8390355 DOI: 10.1111/j.1432-1033.1993.tb17950.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Deletion mutants in the 5' upstream sequence of the human CYP21A2 gene demonstrated a novel regulatory DNA element responsible for cAMP-dependent expression of the gene in the transient expression system using Y-1 cells (mouse adrenocortical tumor cell line). This regulatory element (-2574 to -2489 bp) was also found to exhibit a strong enhancer activity through heterologous promoters in response to cAMP and to contain a sequence like the cAMP-responsive element (CRE) and a CAAT-like sequence. The CRE-like sequence has a five-base motif (5'-TGACG-3') of the palindromic CRE consensus (TGACGTCA). Competitive gel mobility shift assays using nuclear extracts of bovine adrenal cortex with sequences typical of the binding sites for the binding proteins of CRE and the CAAT-like sequence revealed that these binding proteins, or related factors, bound to their cognate DNA binding sites in the upstream enhancer region of the CYP21A2 gene. These two enhancer elements and their cognate binding factors cooperate with previously identified tissue-specific enhancers (adrenal-specific protein factor and Ad4-like sequences) and their binding factors to express a high level of cAMP-responsive expression of the CYP21A2 gene.
Collapse
Affiliation(s)
- N Watanabe
- Department of Chemistry, Faculty of Science, Tohoku University, Sendai, Japan
| | | | | | | | | |
Collapse
|
46
|
Kawajiri K, Nakachi K, Imai K, Watanabe J, Hayashi S. The CYP1A1 gene and cancer susceptibility. Crit Rev Oncol Hematol 1993; 14:77-87. [PMID: 8103989 DOI: 10.1016/1040-8428(93)90007-q] [Citation(s) in RCA: 138] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
A close correlation between cigarette smoking associated lung cancer incidence and an Msp I restriction fragment length polymorphism (RFLP) of the human P-450 1A1 (CYP1A1) gene was found in a Japanese population in terms of genotype frequency and cigarette dose. A Val/Ile codon difference in the primary structure of the CYP1A1 protein (Val-, Ile-type) was in linkage disequilibrium with the Msp I RFLP. A synergistic increase in susceptibility to lung cancer was found when combining genotyping of CYP1A1 and the Mu-class of glutathione S-transferase (GST1). Interindividual variability in the genetic make-up of carcinogen metabolizing enzymes may thus be a key host factor to explain the differences in susceptibility to chemical carcinogenesis among individuals.
Collapse
Affiliation(s)
- K Kawajiri
- Department of Biochemistry, Saitama Cancer Center Research Institute, Japan
| | | | | | | | | |
Collapse
|
47
|
Nonresponsiveness of normal human fibroblasts to dioxin correlates with the presence of a constitutive xenobiotic response element-binding factor. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53580-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
|
48
|
Telhada MB, Pereira TM, Lechner MC. Effect of dexamethasone and phenobarbital on run-on transcription rate and CYP3A mRNA concentration in rat liver: changes during development. Arch Biochem Biophys 1992; 298:715-25. [PMID: 1417000 DOI: 10.1016/0003-9861(92)90471-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Modulation of CYP3A1 and CYP3A2 mRNA expression by dexamethasone and by phenobarbital has been studied in immature (21-day-old) and adult (90-day-old) rat liver. Positive modulation of these forms by both agents markedly declines with the age of the animals. However, CYP3A2 mRNA, although physiologically extinguished in the adult females, still responds to dexamethasone stimulation. The regulatory mechanisms underlying the differential behavior of CYP3A1 in the immature and adult animals have been further investigated by analyzing the early changes in the run-on transcription rates and the subsequent mRNA accumulation in the liver in response to the inducer agents. CYP3A genomic clones were constructed and characterized for this purpose. The use of a unique cosCYP/3A1 intronic sequence, identified in this work, made possible the selective determination of the transcription rate of this gene by run-on assay, as a function of ontological development and inducer treatment. Parallel determination of the mRNA concentration in the liver by dot blot analysis demonstrated that dexamethasone induces CYP3A1 essentially through transcription regulation in immature animals, while in adults it is suggested to act mainly at a post-transcriptional level.
Collapse
Affiliation(s)
- M B Telhada
- Laboratory of Biochemistry, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | | | | |
Collapse
|
49
|
Takimoto K, Lindahl R, Pitot HC. Regulation of 2,3,7,8-tetrachlorodibenzo-p-dioxin-inducible expression of aldehyde dehydrogenase in hepatoma cells. Arch Biochem Biophys 1992; 298:493-7. [PMID: 1416978 DOI: 10.1016/0003-9861(92)90440-8] [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: 12/26/2022]
Abstract
The environmental contaminant, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces the expression of a number of genes. The biochemical process of the induction of aldehyde dehydrogenase (ALDH-3) was investigated in rat H4IIE hepatoma cells in culture. The kinetics of ALDH-3-induction exhibited parallel increases in the rate of transcription, mRNA, protein, and enzyme activity, all reaching a plateau at 36-48 h after addition of TCDD. Half maximal and maximal inductions occurred at 0.1 and 1 nM of TCDD, respectively. No significant changes in the half-life of ALDH-3 mRNA (14 h) were observed in the cells exposed to three different concentrations of TCDD. Other inducers of xenobiotic metabolism, such as 3-methylcholanthrene and beta-naphthoflavone, also induced ALDH-3 mRNA to a similar level as TCDD, whereas antioxidants or electrophiles, such as tert-butylhydroquinone and dimethyl fumarate, did not show any induction of ALDH-3 mRNA. To examine the involvement of the aryl hydrocarbon receptor (Ah receptor) in the induction of ALDH-3, mouse variant cell lines defective in cytochrome P450IA1-induction and a parental wild type cell line (Hepa1c1c7) were studied. ALDH-3 mRNA and the transcription of its gene were detected in TCDD-treated wild type cells, but not in the treated and untreated variant cells. These results demonstrate that TCDD induces transcription of the ALDH-3 gene via its binding to the Ah receptor.
Collapse
MESH Headings
- Aldehyde Dehydrogenase/biosynthesis
- Aldehyde Dehydrogenase/genetics
- Animals
- Blotting, Western
- Enzyme Induction
- Kinetics
- Liver Neoplasms, Experimental/enzymology
- Polychlorinated Dibenzodioxins/pharmacology
- RNA, Messenger/genetics
- RNA, Messenger/isolation & purification
- RNA, Messenger/metabolism
- RNA, Neoplasm/genetics
- RNA, Neoplasm/isolation & purification
- RNA, Neoplasm/metabolism
- Rats
- Transcription, Genetic/drug effects
- Tumor Cells, Cultured
Collapse
Affiliation(s)
- K Takimoto
- McArdle Laboratory for Cancer Research, Department of Oncology, Medical School, University of Wisconsin, Madison 53706
| | | | | |
Collapse
|
50
|
Xanthopoulos KG, Cannon PD, Robinson GS, Mirkovitch J, Darnell JE. Transiently and stably introduced CCAAT/enhancer-binding-protein genes are constitutively expressed in cultured cells. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 208:501-9. [PMID: 1325913 DOI: 10.1111/j.1432-1033.1992.tb17214.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
CCAAT/enhancer-binding protein (C/EBP) is expressed in certain cell types including hepatocytes and adipocytes. In order to understand the mechanisms that control the expression of the mouse C/EBP gene in the liver as well as in adipocytes, we have studied both the endogenous gene and transfected C/EBP gene constructs. The initiation site of transcription was identified and a strong liver-specific DNase-I hypersensitive site located at -3 kb, which does not appear to contribute functionally to the regulation of the gene in a variety of either transiently or stably transfected cells with constructs which include sequences up to 6-kb upstream of the transcription start. C/EBP gene expression during the transition from preadipocytes to adipocytes was shown to be controlled at the level of transcription. However, adipocytes stably transfected with constructs that include -3.3 kb upstream of the C/EBP gene do not express the reporter genes in a differentiation-specific manner. We detected several DNA-binding proteins that interact with the upstream sites of the C/EBP gene. Those include two labile and two heat-stable site-specific DNA-binding proteins that are present in nuclear extracts from several tissues and cultured cell lines.
Collapse
|