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Comparative toxicoproteogenomics of mouse and rat liver identifies TCDD-resistance genes. Arch Toxicol 2019; 93:2961-2978. [DOI: 10.1007/s00204-019-02560-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 09/02/2019] [Indexed: 12/21/2022]
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Viluksela M, Pohjanvirta R. Multigenerational and Transgenerational Effects of Dioxins. Int J Mol Sci 2019; 20:E2947. [PMID: 31212893 PMCID: PMC6627869 DOI: 10.3390/ijms20122947] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 06/12/2019] [Accepted: 06/13/2019] [Indexed: 12/12/2022] Open
Abstract
Dioxins are ubiquitous and persistent environmental contaminants whose background levels are still reason for concern. There is mounting evidence from both epidemiological and experimental studies that paternal exposure to the most potent congener of dioxins, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), can lower the male/female ratio of offspring. Moreover, in laboratory rodents and zebrafish, TCDD exposure of parent animals has been reported to result in reduced reproductive performance along with other adverse effects in subsequent generations, foremost through the paternal but also via the maternal germline. These impacts have been accompanied by epigenetic alterations in placenta and/or sperm cells, including changes in methylation patterns of imprinted genes. Here, we review recent key studies in this field with an attempt to provide an up-to-date picture of the present state of knowledge to the reader. These studies provide biological plausibility for the potential of dioxin exposure at a critical time-window to induce epigenetic alterations across multiple generations and the significance of aryl hydrocarbon receptor (AHR) in mediating these effects. Currently available data do not allow to accurately estimate the human health implications of these findings, although epidemiological evidence on lowered male/female ratio suggests that this effect may take place at realistic human exposure levels.
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Affiliation(s)
- Matti Viluksela
- School of Pharmacy and Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland.
- Environmental Health Unit, National Institute for Health and Welfare, P.O. Box 95, FI-70701 Kuopio, Finland.
| | - Raimo Pohjanvirta
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, FI-00014 Helsinki, Finland.
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Tarnow P, Tralau T, Luch A. Chemical activation of estrogen and aryl hydrocarbon receptor signaling pathways and their interaction in toxicology and metabolism. Expert Opin Drug Metab Toxicol 2019; 15:219-229. [PMID: 30644759 DOI: 10.1080/17425255.2019.1569627] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Estrogen receptors (ERs) and the arylhydrocarbon receptor (AHR) are ligand-activated transcription factors that regulate the expression of genes involved in many physiological processes. With both receptors binding a broad range of natural and anthropogenic ligands, they are molecular targets for many substances, raising concerns for possible health effects. Areas covered: This review shall give a brief overview on the physiological functions of both receptors including their underlying molecular mechanisms. It summarizes the interaction of the respective signaling pathways including impacts on metabolism of endogenous estrogens, transcriptional interference, inhibitory crosstalk, and proteasomal degradation. Also addressed are the AHR dependent formation of estrogenic metabolites from polycyclic aromatic hydrocarbons and the possible impact of the ER/AHR crosstalk in the context of drug metabolism. Expert opinion: Despite decade-long research, the physiological role of the AHR and ER as well as the implications of their complex mutual crosstalk remain to be determined as do resulting potential impacts on human health. With more and more endogenous AHR ligands being discovered, future research should hence systematically address the potential impact of such substances on estrogen signaling. The intimate link between these two pathways and the genes regulated therein bears the potential for impacts on drug metabolism and human health.
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Affiliation(s)
- Patrick Tarnow
- a Department of Chemical & Product Safety , German Federal Institute for Risk Assessment (BfR) , Berlin , Germany
| | - Tewes Tralau
- a Department of Chemical & Product Safety , German Federal Institute for Risk Assessment (BfR) , Berlin , Germany
| | - Andreas Luch
- a Department of Chemical & Product Safety , German Federal Institute for Risk Assessment (BfR) , Berlin , Germany
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Knutsen HK, Alexander J, Barregård L, Bignami M, Brüschweiler B, Ceccatelli S, Cottrill B, Dinovi M, Edler L, Grasl-Kraupp B, Hogstrand C, Nebbia CS, Oswald IP, Petersen A, Rose M, Roudot AC, Schwerdtle T, Vleminckx C, Vollmer G, Wallace H, Fürst P, Håkansson H, Halldorsson T, Lundebye AK, Pohjanvirta R, Rylander L, Smith A, van Loveren H, Waalkens-Berendsen I, Zeilmaker M, Binaglia M, Gómez Ruiz JÁ, Horváth Z, Christoph E, Ciccolallo L, Ramos Bordajandi L, Steinkellner H, Hoogenboom LR. Risk for animal and human health related to the presence of dioxins and dioxin-like PCBs in feed and food. EFSA J 2018; 16:e05333. [PMID: 32625737 PMCID: PMC7009407 DOI: 10.2903/j.efsa.2018.5333] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The European Commission asked EFSA for a scientific opinion on the risks for animal and human health related to the presence of dioxins (PCDD/Fs) and DL-PCBs in feed and food. The data from experimental animal and epidemiological studies were reviewed and it was decided to base the human risk assessment on effects observed in humans and to use animal data as supportive evidence. The critical effect was on semen quality, following pre- and postnatal exposure. The critical study showed a NOAEL of 7.0 pg WHO2005-TEQ/g fat in blood sampled at age 9 years based on PCDD/F-TEQs. No association was observed when including DL-PCB-TEQs. Using toxicokinetic modelling and taking into account the exposure from breastfeeding and a twofold higher intake during childhood, it was estimated that daily exposure in adolescents and adults should be below 0.25 pg TEQ/kg bw/day. The CONTAM Panel established a TWI of 2 pg TEQ/kg bw/week. With occurrence and consumption data from European countries, the mean and P95 intake of total TEQ by Adolescents, Adults, Elderly and Very Elderly varied between, respectively, 2.1 to 10.5, and 5.3 to 30.4 pg TEQ/kg bw/week, implying a considerable exceedance of the TWI. Toddlers and Other Children showed a higher exposure than older age groups, but this was accounted for when deriving the TWI. Exposure to PCDD/F-TEQ only was on average 2.4- and 2.7-fold lower for mean and P95 exposure than for total TEQ. PCDD/Fs and DL-PCBs are transferred to milk and eggs, and accumulate in fatty tissues and liver. Transfer rates and bioconcentration factors were identified for various species. The CONTAM Panel was not able to identify reference values in most farm and companion animals with the exception of NOAELs for mink, chicken and some fish species. The estimated exposure from feed for these species does not imply a risk.
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Helle J, Keiler AM, Zierau O, Dörfelt P, Vollmer G, Lehmann L, Chittur SV, Tenniswood M, Welsh J, Kretzschmar G. Effects of the aryl hydrocarbon receptor agonist 3-methylcholanthrene on the 17β-estradiol regulated mRNA transcriptome of the rat uterus. J Steroid Biochem Mol Biol 2017; 171:133-143. [PMID: 28285017 DOI: 10.1016/j.jsbmb.2017.03.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 03/01/2017] [Accepted: 03/06/2017] [Indexed: 10/20/2022]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are products of incomplete combustion of organic compounds, abundant in exhaust fumes and cigarette smoke. They act by binding to the aryl hydrocarbon receptor (AHR) which induces expression of phase 1 and phase 2 enzymes in the liver. PAH induced AHR activation may also lead to adverse effects by modulating other pathways, for example estrogen receptor (ER) signaling in the female reproductive tract. We have investigated the effects of the PAH 3-methylcholanthrene (3-MC) on 17β-estradiol (E2) dependent signaling in the uterus of ovariectomized rats to characterize the cross talk between AHR and ER on an mRNA transcriptome wide scale. A standard three day uterotrophic assay was performed in young adult Lewis rats. Treatment induced effects were analyzed using histology, immunohistochemistry and gene expression analysis by microarray and qPCR. 3-MC shows broad E2 antagonistic effects on uterine mRNA transcription of the vast majority of E2 regulated genes, significantly altering prostaglandin biosynthesis, complement activation, coagulation pathways and other inflammatory response pathways. The regulation of ER expression in the uterus, but not the regulation of E2 metabolism in the liver, was identified as a potentially important factor in mediating this general antiestrogenic effect. The regulation of prostaglandin biosynthesis by E2 is important for inflammation-like events during pregnancy including the initiation of birth. Our results suggest that adverse effects of PAHs on prostaglandin related pathways are likely caused by the interference with E2 signaling, specifically by inhibiting the E2 mediated downregulation of PGF2α. Characterization of the generalized antagonistic effect of 3-MC on E2 dependent signaling in the rat uterus thus contributes to a better understanding of molecular mechanisms of the toxicity of PAHs in female reproductive organs.
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Affiliation(s)
- Janina Helle
- Institute of Zoology, Molecular Cell Physiology and Endocrinology, Technische Universität Dresden, 01062, Dresden, Germany
| | - Annekathrin M Keiler
- Institute of Zoology, Molecular Cell Physiology and Endocrinology, Technische Universität Dresden, 01062, Dresden, Germany
| | - Oliver Zierau
- Institute of Zoology, Molecular Cell Physiology and Endocrinology, Technische Universität Dresden, 01062, Dresden, Germany
| | - Peggy Dörfelt
- Institute of Zoology, Molecular Cell Physiology and Endocrinology, Technische Universität Dresden, 01062, Dresden, Germany
| | - Günter Vollmer
- Institute of Zoology, Molecular Cell Physiology and Endocrinology, Technische Universität Dresden, 01062, Dresden, Germany
| | - Leane Lehmann
- Institute of Pharmacy and Food Chemistry, Universität Würzburg, 97070 Würzburg, Germany
| | - Sridar V Chittur
- Cancer Research Center and Department of Biomedical Sciences, University at Albany, NY 12144-2345, United States
| | - Martin Tenniswood
- Cancer Research Center and Department of Biomedical Sciences, University at Albany, NY 12144-2345, United States
| | - JoEllen Welsh
- Cancer Research Center and Department of Biomedical Sciences, University at Albany, NY 12144-2345, United States
| | - Georg Kretzschmar
- Institute of Zoology, Molecular Cell Physiology and Endocrinology, Technische Universität Dresden, 01062, Dresden, Germany.
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Helle J, Bader MI, Keiler AM, Zierau O, Vollmer G, Chittur SV, Tenniswood M, Kretzschmar G. Cross-Talk in the Female Rat Mammary Gland: Influence of Aryl Hydrocarbon Receptor on Estrogen Receptor Signaling. ENVIRONMENTAL HEALTH PERSPECTIVES 2016; 124:601-610. [PMID: 26372666 PMCID: PMC4858405 DOI: 10.1289/ehp.1509680] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 09/10/2015] [Indexed: 06/05/2023]
Abstract
BACKGROUND Cross-talk between the aryl hydrocarbon receptor (AHR) and the estrogen receptor (ER) plays a major role in signaling processes in female reproductive organs. OBJECTIVES We investigated the influence of the AHR ligand 3-methylcholanthrene (3-MC) on ER-mediated signaling in mammary gland tissue of ovariectomized (ovx) rats. METHODS After 14 days of hormonal decline, ovx rats were treated for 3 days with 4 μg/kg 17β-estradiol (E2), 15 mg/kg 8-prenylnaringenin (8-PN), 15 mg/kg 3-MC, or a combination of these compounds (E2 + 3-MC, 8-PN + 3-MC). Whole-mount preparations of the mammary gland were used to count terminal end buds (TEBs). Protein expression studies (immunohistochemistry, immunofluorescence), a cDNA microarray, pathway analyses, and quantitative real-time polymerase chain reaction (qPCR) were performed to evaluate the interaction between AHR- and ER-mediated signaling pathways. RESULTS E2 treatment increased the number of TEBs and the levels of Ki-67 protein and progesterone receptor (PR); this treatment also changed the expression of 325 genes by more than 1.5-fold. Although 3-MC treatment alone had marginal impact on gene or protein expression, when rats were co-treated with 3-MC and E2, 3-MC strongly inhibited E2-induced TEB development, protein synthesis, and the expression of nearly half of E2-induced genes. This inhibitory effect of 3-MC was partially mirrored when 8-PN was used as an ER ligand. The anti-estrogenicity of ligand-activated AHR was at least partly due to decreased protein levels of ERα in ductal epithelial cells. CONCLUSION Our data show transcriptome-wide anti-estrogenic properties of ligand-activated AHR on ER-mediated processes in the mammary gland, thereby contributing an explanation for the chemopreventive and endocrine-disrupting potential of AHR ligands. CITATION Helle J, Bader MI, Keiler AM, Zierau O, Vollmer G, Chittur SV, Tenniswood M, Kretzschmar G. 2016. Cross-talk in the female rat mammary gland: influence of aryl hydrocarbon receptor on estrogen receptor signaling. Environ Health Perspect 124:601-610; http://dx.doi.org/10.1289/ehp.1509680.
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Affiliation(s)
- Janina Helle
- Institute of Zoology, Molecular Cell Physiology and Endocrinology, Technische Universität Dresden, Dresden, Germany
| | - Manuela I. Bader
- Institute of Zoology, Molecular Cell Physiology and Endocrinology, Technische Universität Dresden, Dresden, Germany
| | - Annekathrin M. Keiler
- Institute of Zoology, Molecular Cell Physiology and Endocrinology, Technische Universität Dresden, Dresden, Germany
| | - Oliver Zierau
- Institute of Zoology, Molecular Cell Physiology and Endocrinology, Technische Universität Dresden, Dresden, Germany
| | - Günter Vollmer
- Institute of Zoology, Molecular Cell Physiology and Endocrinology, Technische Universität Dresden, Dresden, Germany
| | - Sridar V. Chittur
- Department of Biomedical Sciences, University at Albany, State University of New York, Albany, New York, USA
| | - Martin Tenniswood
- Department of Biomedical Sciences, University at Albany, State University of New York, Albany, New York, USA
| | - Georg Kretzschmar
- Institute of Zoology, Molecular Cell Physiology and Endocrinology, Technische Universität Dresden, Dresden, Germany
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Prokopec SD, Watson JD, Lee J, Pohjanvirta R, Boutros PC. Sex-related differences in murine hepatic transcriptional and proteomic responses to TCDD. Toxicol Appl Pharmacol 2015; 284:188-96. [PMID: 25703434 DOI: 10.1016/j.taap.2015.02.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 02/06/2015] [Accepted: 02/10/2015] [Indexed: 12/14/2022]
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is an environmental contaminant that produces myriad toxicities in most mammals. In rodents alone, there is a huge divergence in the toxicological response across species, as well as among different strains within a species. But there are also significant differences between males and females animals of a single strain. These differences are inconsistent across model systems: the severity of toxicity is greater in female rats than males, while male mice and guinea pigs are more sensitive than females. Because the specific events that underlie this difference remain unclear, we characterized the hepatic transcriptional response of adult male and female C57BL/6 mice to 500μg/kg TCDD at multiple time-points. The transcriptional profile diverged significantly between the sexes. Female mice demonstrated a large number of altered transcripts as early as 6h following treatment, suggesting a large primary response. Conversely, male animals showed the greatest TCDD-mediated response 144h following exposure, potentially implicating significant secondary responses. Nr1i3 was statistically significantly induced at all time-points in the sensitive male animals. This mRNA encodes the constitutive androstane receptor (CAR), a transcription factor involved in the regulation of xenobiotic metabolism, lipid metabolism, cell cycle and apoptosis. Surprisingly though, changes at the protein level (aside from the positive control, CYP1A1) were modest, with only FMO3 showing clear induction, and no genes with sex-differences. Thus, while male and female mice show transcriptional differences in their response to TCDD, their association with TCDD-induced toxicities remains unclear.
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Affiliation(s)
- Stephenie D Prokopec
- Informatics and Bio-computing Program, Ontario Institute for Cancer Research, Toronto, Canada
| | - John D Watson
- Informatics and Bio-computing Program, Ontario Institute for Cancer Research, Toronto, Canada
| | - Jamie Lee
- Informatics and Bio-computing Program, Ontario Institute for Cancer Research, Toronto, Canada; Department of Pharmacology & Toxicology, University of Toronto, Toronto, Canada
| | - Raimo Pohjanvirta
- Laboratory of Toxicology, National Institute for Health and Welfare, Kuopio Finland; Department of Food Hygiene and Environmental Health, University of Helsinki, Helsinki, Finland
| | - Paul C Boutros
- Informatics and Bio-computing Program, Ontario Institute for Cancer Research, Toronto, Canada; Department of Pharmacology & Toxicology, University of Toronto, Toronto, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Canada.
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Watson JD, Prokopec SD, Smith AB, Okey AB, Pohjanvirta R, Boutros PC. TCDD dysregulation of 13 AHR-target genes in rat liver. Toxicol Appl Pharmacol 2014; 274:445-54. [DOI: 10.1016/j.taap.2013.12.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 12/02/2013] [Accepted: 12/05/2013] [Indexed: 12/20/2022]
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Prokopec SD, Watson JD, Waggott DM, Smith AB, Wu AH, Okey AB, Pohjanvirta R, Boutros PC. Systematic evaluation of medium-throughput mRNA abundance platforms. RNA (NEW YORK, N.Y.) 2013; 19:51-62. [PMID: 23169800 PMCID: PMC3527726 DOI: 10.1261/rna.034710.112] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Accepted: 10/10/2012] [Indexed: 05/22/2023]
Abstract
Profiling of mRNA abundances with high-throughput platforms such as microarrays and RNA-seq has become an important tool in both basic and biomedical research. However, these platforms remain prone to systematic errors and have challenges in clinical and industrial applications. As a result, it is standard practice to validate a subset of key results using alternate technologies. Similarly, clinical and industrial applications typically involve transitions from a high-throughput discovery platform to medium-throughput validation ones. These medium-throughput validation platforms have high technical reproducibility and reduced sample input needs, and low sensitivity to sample quality (e.g., for processing FFPE specimens). Unfortunately, while medium-throughput platforms have proliferated, there are no comprehensive comparisons of them. Here we fill that gap by comparing two key medium-throughput platforms--NanoString's nCounter Analysis System and ABI's OpenArray System--to gold-standard quantitative real-time RT-PCR. We quantified 38 genes and positive and negative controls in 165 samples. Signal:noise ratios, correlations, dynamic range, and detection accuracy were compared across platforms. All three measurement technologies showed good concordance, but with divergent price/time/sensitivity trade-offs. This study provides the first detailed comparison of medium-throughput RNA quantification platforms and provides a template and a standard data set for the evaluation of additional technologies.
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Affiliation(s)
- Stephenie D. Prokopec
- Informatics and Biocomputing Platform, Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3, Canada
| | - John D. Watson
- Informatics and Biocomputing Platform, Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3, Canada
| | - Daryl M. Waggott
- Informatics and Biocomputing Platform, Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3, Canada
| | - Ashley B. Smith
- Informatics and Biocomputing Platform, Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3, Canada
| | - Alexander H. Wu
- Informatics and Biocomputing Platform, Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3, Canada
| | - Allan B. Okey
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Raimo Pohjanvirta
- Laboratory of Toxicology, Department of Environmental Health, National Public Health Institute, FIN-70701 Kuopio, Finland
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, FI-00014 Helsinki, Finland
| | - Paul C. Boutros
- Informatics and Biocomputing Platform, Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9, Canada
- Corresponding authorE-mail
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Bebenek IG, Solaimani P, Bui P, Hankinson O. CYP2S1 is negatively regulated by corticosteroids in human cell lines. Toxicol Lett 2011; 209:30-4. [PMID: 22155357 DOI: 10.1016/j.toxlet.2011.11.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 11/21/2011] [Accepted: 11/22/2011] [Indexed: 01/04/2023]
Abstract
Cytochrome P450s are monooxygenase proteins involved in the metabolism of both exogenous and endogenous compounds. CYP2S1 can metabolize eicosanoids in the absence of both NADPH and NADPH cytochrome P450 reductase, and can also activate the anticancer agent 1 AQ4N [1,4-bis{[2-(dimethylamino-N-oxide)ethyl]amino}-5,8-dihydroxy anthracene-9,10-dione]. CYP2S1 is mainly expressed in extrahepatic tissues such as the trachea, lung, stomach, small intestine, spleen, skin, breast, kidney and placenta. Furthermore, increased expression of CYP2S1 occurs in several tumors of epithelial origin, making the characterization of CYP2S1 regulation relevant to the treatment of disease. We report that the synthetic glucocorticoid receptor ligand dexamethasone (DEX) represses CYP2S1 expression. The ED(50) is between 1 nM and 3 nM and maximal repression is reached by 48 h. Other corticosteroids are also effective at repressing CYP2S1. We show that repression by DEX is mediated by the glucocorticoid receptor and requires histone deacetylase activity.
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Affiliation(s)
- Ilona G Bebenek
- Molecular Toxicology Interdepartmental Program, Department of Pathology and Laboratory Medicine, and the Jonsson Comprehensive Cancer Center, University of California, Los Angeles, CA 90095, USA
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Wang B, Robertson LW, Wang K, Ludewig G. Species difference in the regulation of cytochrome P450 2S1: lack of induction in rats by the aryl hydrocarbon receptor agonist PCB126. Xenobiotica 2011; 41:1031-43. [PMID: 21970748 DOI: 10.3109/00498254.2011.603763] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CYP2S1 is an evolutionarily conserved, mainly extra-hepatic member of the CYP2 family and proposed to be regulated by the aryl hydrocarbon receptor (AhR). The present study explores AhR's regulation of CYP2S1 in male Sprague Dawley rats using PCB126 (3,3',4,4',5-pentachlorobiphenyl), the most potent AhR agonist among the PCBs. Additionally, CYP2S1 expression was examined after treatments with the classic CYP-inducers β-naphthoflavone (β-NF, AhR activator), phenobarbital (PB, CAR activator) and dexamethasone (Dex, PXR activator). CYP2S1 and CYP1A1/2, CYP1B1, CYP2B and CYP3A mRNAs were measured in liver, lung, spleen, stomach, kidney, and thymus at different time points. Constitutive CYP2S1 was expressed at comparable levels to other CYPs with the highest expression levels in stomach, kidney and lung. CYP2S1 mRNA was only non-significantly elevated by β-NF in liver tissues. PCB126 did not increase CYP2S1 mRNA in any organ and at any time point examined despite a significant induction of CYP1 genes. PCB126 reduced CYP2S1 mRNA by 40% (not significant) from the 7th post-exposure day in thymus. PB and Dex had no effect on CYP2S1 mRNA levels. These observations show that in this model CYP2S1 is not, or only weakly, regulated by AhR and not induced by CAR or PXR activators.
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Affiliation(s)
- Bingxuan Wang
- Human Toxicology, University of Iowa, Iowa City, USA
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Jacob A, Hartz AM, Potin S, Coumoul X, Yousif S, Scherrmann JM, Bauer B, Declèves X. Aryl hydrocarbon receptor-dependent upregulation of Cyp1b1 by TCDD and diesel exhaust particles in rat brain microvessels. Fluids Barriers CNS 2011; 8:23. [PMID: 21867498 PMCID: PMC3180256 DOI: 10.1186/2045-8118-8-23] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Accepted: 08/25/2011] [Indexed: 12/14/2022] Open
Abstract
Background AhR activates the transcription of several target genes including CYP1B1. Recently, we showed CYP1B1 as the major cytochrome P450 (CYP) enzyme expressed in human brain microvessels. Here, we studied the effect of AhR activation by environmental pollutants on the expression of Cyp1b1 in rat brain microvessels. Methods Expression of AhR and Cyp1b1 was detected in isolated rat brain microvessels. AhR was immunovisualised in brain microvessel endothelial cells. The effect of AhR ligands on Cyp1b1 expression was studied using isolated brain microvessels after ex vivo and/or in vivo exposure to TCDD, heavy hydrocarbons containing diesel exhaust particles (DEP) or Δ9-tetrahydrocannabinol (Δ9-THC). Results After ex vivo exposure to TCDD (a highly potent AhR ligand) for 3 h, Cyp1b1 expression was significantly increased by 2.3-fold in brain microvessels. A single i.p. dose of TCDD also increased Cyp1b1 transcripts (22-fold) and Cyp1b1 protein (2-fold) in rat brain microvessels at 72 h after TCDD. Likewise, DEP treatment (in vivo and ex vivo) strongly induced Cyp1b1 protein in brain microvessels. DEP-mediated Cyp1b1 induction was inhibited by actinomycin D, cycloheximide, or by an AhR antagonist. In contrast, a sub-chronic in vivo treatment with Δ9-THC once daily for 7 seven days had no effect on Cyp1b1 expression Conclusions Our results show that TCDD and DEP strongly induced Cyp1b1 in rat brain microvessels, likely through AhR activation.
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Affiliation(s)
- Aude Jacob
- Neuropsychopharmacologie des addictions (CNRS UMR 8206), Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France.
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Celius T, Pansoy A, Matthews J, Okey AB, Henderson MC, Krueger SK, Williams DE. Flavin-containing monooxygenase-3: induction by 3-methylcholanthrene and complex regulation by xenobiotic chemicals in hepatoma cells and mouse liver. Toxicol Appl Pharmacol 2010; 247:60-9. [PMID: 20570689 DOI: 10.1016/j.taap.2010.05.018] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Revised: 04/28/2010] [Accepted: 05/25/2010] [Indexed: 12/15/2022]
Abstract
Flavin-containing monooxygenases often are thought not to be inducible but we recently demonstrated aryl hydrocarbon receptor (AHR)-dependent induction of FMO mRNAs in mouse liver by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (Celius et al., Drug Metab Dispos 36:2499, 2008). We now evaluated FMO induction by other AHR ligands and xenobiotic chemicals in vivo and in mouse Hepa1c1c7 hepatoma cells (Hepa-1). In mouse liver, 3-methylcholanthrene (3MC) induced FMO3 mRNA 8-fold. In Hepa-1 cells, 3MC and benzo[a]pyrene (BaP) induced FMO3 mRNA >30-fold. Induction by 3MC and BaP was AHR dependent but, surprisingly, the potent AHR agonist, TCDD, did not induce FMO3 mRNA in Hepa-1 cells nor did chromatin immunoprecipitation assays detect recruitment of AHR or ARNT to Fmo3 regulatory elements after exposure to 3MC in liver or in Hepa-1 cells. However, in Hepa-1, 3MC and BaP (but not TCDD) caused recruitment of p53 protein to a p53 response element in the 5'-flanking region of the Fmo3 gene. We tested the possibility that FMO3 induction in Hepa-1 cells might be mediated by Nrf2/anti-oxidant response pathways, but agents known to activate Nrf2 or to induce oxidative stress did not affect FMO3 mRNA levels. The protein synthesis inhibitor, cycloheximide (which causes "superinduction" of CYP1A1 mRNA in TCDD-treated cells), by itself caused dramatic upregulation (>300-fold) of FMO3 mRNA in Hepa-1 suggesting that cycloheximide prevents synthesis of a labile protein that suppresses FMO3 expression. Although FMO3 mRNA is highly induced by 3MC or TCDD in mouse liver and in Hepa-1 cells, FMO protein levels and FMO catalytic function showed only modest elevation.
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Affiliation(s)
- Trine Celius
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada.
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