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Veland N, Gleneadie HJ, Brown KE, Sardini A, Pombo J, Dimond A, Burns V, Sarkisyan K, Schiering C, Webster Z, Merkenschlager M, Fisher AG. Bioluminescence imaging of Cyp1a1-luciferase reporter mice demonstrates prolonged activation of the aryl hydrocarbon receptor in the lung. Commun Biol 2024; 7:442. [PMID: 38600349 PMCID: PMC11006662 DOI: 10.1038/s42003-024-06089-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 03/21/2024] [Indexed: 04/12/2024] Open
Abstract
Aryl hydrocarbon receptor (AHR) signalling integrates biological processes that sense and respond to environmental, dietary, and metabolic challenges to ensure tissue homeostasis. AHR is a transcription factor that is inactive in the cytosol but upon encounter with ligand translocates to the nucleus and drives the expression of AHR targets, including genes of the cytochrome P4501 family of enzymes such as Cyp1a1. To dynamically visualise AHR activity in vivo, we generated reporter mice in which firefly luciferase (Fluc) was non-disruptively targeted into the endogenous Cyp1a1 locus. Exposure of these animals to FICZ, 3-MC or to dietary I3C induced strong bioluminescence signal and Cyp1a1 expression in many organs including liver, lung and intestine. Longitudinal studies revealed that AHR activity was surprisingly long-lived in the lung, with sustained Cyp1a1 expression evident in discrete populations of cells including columnar epithelia around bronchioles. Our data link diet to lung physiology and also reveal the power of bespoke Cyp1a1-Fluc reporters to longitudinally monitor AHR activity in vivo.
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Affiliation(s)
- Nicolas Veland
- Epigenetic Memory Group, MRC Laboratory of Medical Sciences, Imperial College London Hammersmith Hospital Campus, Du Cane Road, London, W12 OHS, UK
| | - Hannah J Gleneadie
- Epigenetic Memory Group, MRC Laboratory of Medical Sciences, Imperial College London Hammersmith Hospital Campus, Du Cane Road, London, W12 OHS, UK
| | - Karen E Brown
- Epigenetic Memory Group, MRC Laboratory of Medical Sciences, Imperial College London Hammersmith Hospital Campus, Du Cane Road, London, W12 OHS, UK
| | - Alessandro Sardini
- Whole Animal Physiology and Imaging, MRC Laboratory of Medical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0HS, UK
| | - Joaquim Pombo
- Senescence Group, MRC Laboratory of Medical Sciences, Imperial College London Hammersmith Hospital Campus, Du Cane Road, London, W12 0HS, UK
| | - Andrew Dimond
- Epigenetic Memory Group, MRC Laboratory of Medical Sciences, Imperial College London Hammersmith Hospital Campus, Du Cane Road, London, W12 OHS, UK
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Vanessa Burns
- Epigenetic Memory Group, MRC Laboratory of Medical Sciences, Imperial College London Hammersmith Hospital Campus, Du Cane Road, London, W12 OHS, UK
| | - Karen Sarkisyan
- Synthetic Biology Group, MRC Laboratory of Medical Sciences, Imperial College London Hammersmith Hospital Campus, Du Cane Road, London, W12 0HS, UK
| | - Chris Schiering
- Inflammation and Obesity Group, MRC Laboratory of Medical Sciences, Imperial College London Hammersmith Hospital Campus, Du Cane Road, London, W12 0HS, UK
| | - Zoe Webster
- Transgenics & Embryonic Stem Cell Facility, MRC Laboratory of Medical Sciences, Imperial College London Hammersmith Hospital Campus, Du Cane Road, London, W12 0HS, UK
| | - Matthias Merkenschlager
- Lymphocyte Development Group, MRC Laboratory of Medical Sciences, Imperial College London Hammersmith Hospital Campus, Du Cane Road, London, W12 0HS, UK
| | - Amanda G Fisher
- Epigenetic Memory Group, MRC Laboratory of Medical Sciences, Imperial College London Hammersmith Hospital Campus, Du Cane Road, London, W12 OHS, UK.
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
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Fitriasari S, Trainor PA. Gene-environment interactions in the pathogenesis of common craniofacial anomalies. Curr Top Dev Biol 2022; 152:139-168. [PMID: 36707210 DOI: 10.1016/bs.ctdb.2022.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Craniofacial anomalies often exhibit phenotype variability and non-mendelian inheritance due to their multifactorial origin, involving both genetic and environmental factors. A combination of epidemiologic studies, genome-wide association, and analysis of animal models have provided insight into the effects of gene-environment interactions on craniofacial and brain development and the pathogenesis of congenital disorders. In this chapter, we briefly summarize the etiology and pathogenesis of common craniofacial anomalies, focusing on orofacial clefts, hemifacial microsomia, and microcephaly. We then discuss how environmental risk factors interact with genes to modulate the incidence and phenotype severity of craniofacial anomalies. Identifying environmental risk factors and dissecting their interaction with different genes and modifiers is central to improved strategies for preventing craniofacial anomalies.
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Affiliation(s)
| | - Paul A Trainor
- Stowers Institute for Medical Research, Kansas City, MO, United States; Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS, United States.
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Structure-based virtual screening of CYP1A1 inhibitors: towards rapid tier-one assessment of potential developmental toxicants. Arch Toxicol 2021; 95:3031-3048. [PMID: 34181028 PMCID: PMC8380238 DOI: 10.1007/s00204-021-03111-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 06/17/2021] [Indexed: 10/26/2022]
Abstract
Cytochrome P450 1A1 (CYP1A1) metabolizes estrogens, melatonin, and other key endogenous signaling molecules critical for embryonic/fetal development. The enzyme has increasing expression during pregnancy, and its inhibition or knockout increases embryonic/fetal lethality and/or developmental problems. Here, we present a virtual screening model for CYP1A1 inhibitors based on the orthosteric and predicted allosteric sites of the enzyme. Using 1001 reference compounds with CYP1A1 activity data, we optimized the decision thresholds of our model and classified the training compounds with 68.3% balanced accuracy (91.0% sensitivity and 45.7% specificity). We applied our final model to 11 known CYP1A1 orthosteric binders and related compounds, and found that our ranking of the known orthosteric binders generally agrees with the relative activity of CYP1A1 in metabolizing these compounds. We also applied the model to 22 new test compounds with unknown/unclear CYP1A1 inhibitory activity, and predicted 16 of them are CYP1A1 inhibitors. The CYP1A1 potency and modes of inhibition of these 22 compounds were experimentally determined. We confirmed that most predicted inhibitors, including drugs contraindicated during pregnancy (amiodarone, bicalutamide, cyproterone acetate, ketoconazole, and tamoxifen) and environmental agents suspected to be endocrine disruptors (bisphenol A, diethyl and dibutyl phthalates, and zearalenone), are indeed potent inhibitors of CYP1A1. Our results suggest that virtual screening may be used as a rapid tier-one method to screen for potential CYP1A1 inhibitors, and flag them out for further experimental evaluations.
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Rannug A, Rannug U. The tryptophan derivative 6-formylindolo[3,2-b]carbazole, FICZ, a dynamic mediator of endogenous aryl hydrocarbon receptor signaling, balances cell growth and differentiation. Crit Rev Toxicol 2018; 48:555-574. [PMID: 30226107 DOI: 10.1080/10408444.2018.1493086] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The aryl hydrocarbon receptor (AHR) is not essential to survival, but does act as a key regulator of many normal physiological events. The role of this receptor in toxicological processes has been studied extensively, primarily employing the high-affinity ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). However, regulation of physiological responses by endogenous AHR ligands remains to be elucidated. Here, we review developments in this field, with a focus on 6-formylindolo[3,2-b]carbazole (FICZ), the endogenous ligand with the highest affinity to the receptor reported to date. The binding of FICZ to different isoforms of the AHR seems to be evolutionarily well conserved and there is a feedback loop that controls AHR activity through metabolic degradation of FICZ via the highly inducible cytochrome P450 1A1. Several investigations provide strong evidence that FICZ plays a critical role in normal physiological processes and can ameliorate immune diseases with remarkable efficiency. Low levels of FICZ are pro-inflammatory, providing resistance to pathogenic bacteria, stimulating the anti-tumor functions, and promoting the differentiation of cancer cells by repressing genes in cancer stem cells. In contrast, at high concentrations FICZ behaves in a manner similar to TCDD, exhibiting toxicity toward fish and bird embryos, immune suppression, and activation of cancer progression. The findings are indicative of a dual role for endogenously activated AHR in barrier tissues, aiding clearance of infections and suppressing immunity to terminate a vicious cycle that might otherwise lead to disease. There is not much support for the AHR ligand-specific immune responses proposed, the differences between FICZ and TCDD in this context appear to be explained by the rapid metabolism of FICZ.
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Affiliation(s)
- Agneta Rannug
- a Karolinska Institutet, Institute of Environmental Medicine , Stockholm , Sweden
| | - Ulf Rannug
- b Department of Molecular Biosciences , The Wenner-Gren Institute, Stockholm University , Stockholm , Sweden
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Gutiérrez-Vázquez C, Quintana FJ. Regulation of the Immune Response by the Aryl Hydrocarbon Receptor. Immunity 2018; 48:19-33. [PMID: 29343438 DOI: 10.1016/j.immuni.2017.12.012] [Citation(s) in RCA: 568] [Impact Index Per Article: 94.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 10/04/2017] [Accepted: 12/21/2017] [Indexed: 12/14/2022]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that is activated by small molecules provided by the diet, microorganisms, metabolism, and pollutants. AhR is expressed by a number of immune cells, and thus AhR signaling provides a molecular pathway that integrates the effects of the environment and metabolism on the immune response. Studies have shown that AhR signaling plays important roles in the immune system in health and disease. As its activity is regulated by small molecules, AhR also constitutes a potential target for therapeutic immunomodulation. In this review we discuss the role of AhR in the regulation of the immune response in the context of autoimmunity, infection, and cancer, as well as the potential opportunities and challenges of developing AhR-targeted therapeutics.
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Affiliation(s)
- Cristina Gutiérrez-Vázquez
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Francisco J Quintana
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA; The Broad Institute of MIT and Harvard, Cambridge, MA, USA.
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Maturu P, Wei-Liang Y, Jiang W, Wang L, Lingappan K, Barrios R, Liang Y, Moorthy B, Couroucli XI. Newborn Mice Lacking the Gene for Cyp1a1 Are More Susceptible to Oxygen-Mediated Lung Injury, and Are Rescued by Postnatal β-Naphthoflavone Administration: Implications for Bronchopulmonary Dysplasia in Premature Infants. Toxicol Sci 2018; 157:260-271. [PMID: 28201809 DOI: 10.1093/toxsci/kfx036] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Prolonged hyperoxia contributes to bronchopulmonary dysplasia (BPD) in preterm infants. β-Naphthoflavone (BNF) is a potent inducer of cytochrome P450 (CYP)1A enzymes, which have been implicated in hyperoxic injuries in adult mice. In this investigation, we tested the hypothesis that newborn mice lacking the Cyp1a1 gene would be more susceptible to hyperoxic lung injury than wild-type (WT) mice and that postnatal BNF treatment would rescue this phenotype by mechanisms involving CYP1A and/or NAD(P)H quinone oxidoreductase (NQO1) enzymes. Newborn WT or Cyp1a1-null mice were treated with BNF (10 mg/kg) or the vehicle corn oil (CO) i.p., from postnatal day (PND) 2 to 14 once every other day, while being maintained in room air or hyperoxia (85% O2) for 14 days. Both genotypes showed lung injury, inflammation, and alveolar simplification in hyperoxia, with Cyp1a1-null mice displaying increased susceptibility compared to WT mice. BNF treatment resulted in significant attenuation of lung injury and inflammation, with improved alveolarization in both WT and Cyp1a1-null mice. BNF exposed normoxic or hyperoxic WT mice showed increased expression of hepatic CYP1A1/1A2, pulmonary CYP1A1, and NQO1 expression at both mRNA and protein levels, compared with vehicle controls. However, BNF caused greater induction of hepatic CYP1A2 and pulmonary NQO1 enzymes in the Cyp1a1-null mice, suggesting that BNF protects against hyperoxic lung injury in WT and Cyp1a1-null mice through the induction of CYP1A and NQO1 enzymes. Further studies on the protective role of flavonoids against hyperoxic lung injury in newborns could lead to novel strategies for the prevention and/or treatment of BPD.
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Affiliation(s)
- Paramahamsa Maturu
- Section of Neonatology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA
| | - Yanhong Wei-Liang
- Section of Neonatology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA
| | - Weiwu Jiang
- Section of Neonatology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA
| | - Lihua Wang
- Section of Neonatology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA
| | - Krithika Lingappan
- Section of Neonatology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA
| | - Roberto Barrios
- Department of Pathology and Genomic Medicine, The Methodist Hospital Physician Organization, Houston, Texas, USA
| | - Yao Liang
- Section of Neonatology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA
| | - Bhagavatula Moorthy
- Section of Neonatology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA
| | - Xanthi I Couroucli
- Section of Neonatology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA
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Regulation of Human Cytochrome P4501A1 (hCYP1A1): A Plausible Target for Chemoprevention? BIOMED RESEARCH INTERNATIONAL 2016; 2016:5341081. [PMID: 28105425 PMCID: PMC5220472 DOI: 10.1155/2016/5341081] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 11/09/2016] [Accepted: 11/13/2016] [Indexed: 12/13/2022]
Abstract
Human cytochrome P450 1A1 (hCYP1A1) has been an object of study due to its role in precarcinogen metabolism; for this reason it is relevant to know more in depth the mechanisms that rule out its expression and activity, which make this enzyme a target for the development of novel chemiopreventive agents. The aim of this work is to review the origin, regulation, and structural and functional characteristics of CYP1A1 letting us understand its role in the bioactivation of precarcinogen and the consequences of its modulation in other physiological processes, as well as guide us in the study of this important protein.
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Henderson CJ, McLaughlin LA, Osuna-Cabello M, Taylor M, Gilbert I, McLaren AW, Wolf CR. Application of a novel regulatable Cre recombinase system to define the role of liver and gut metabolism in drug oral bioavailability. Biochem J 2015; 465:479-88. [PMID: 25377919 PMCID: PMC6949133 DOI: 10.1042/bj20140582] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The relative contribution of hepatic compared with intestinal oxidative metabolism is a crucial factor in drug oral bioavailability and therapeutic efficacy. Oxidative metabolism is mediated by the cytochrome P450 mono-oxygenase system to which cytochrome P450 reductase (POR) is the essential electron donor. In order to study the relative importance of these pathways in drug disposition, we have generated a novel mouse line where Cre recombinase is driven off the endogenous Cyp1a1 gene promoter; this line was then crossed on to a floxed POR mouse. A 40 mg/kg dose of the Cyp1a1 inducer 3-methylcholanthrene (3MC) eliminated POR expression in both liver and small intestine, whereas treatment at 4 mg/kg led to a more targeted deletion in the liver. Using this approach, we have studied the pharmacokinetics of three probe drugs--paroxetine, midazolam, nelfinavir--and show that intestinal metabolism is a determinant of oral bioavailability for the two latter compounds. The Endogenous Reductase Locus (ERL) mouse represents a significant advance on previous POR deletion models as it allows direct comparison of hepatic and intestinal effects on drug and xenobiotic clearance using lower doses of a single Cre inducing agent, and in addition minimizes any cytotoxic effects, which may compromise interpretation of the experimental data.
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Affiliation(s)
- Colin J. Henderson
- Division of Cancer Research, Level 9, Jacqui Wood Cancer Centre, University of Dundee, Ninewells Hospital & Medical School, Dundee DD1 9SY, U.K
| | - Lesley A. McLaughlin
- Division of Cancer Research, Level 9, Jacqui Wood Cancer Centre, University of Dundee, Ninewells Hospital & Medical School, Dundee DD1 9SY, U.K
| | - Maria Osuna-Cabello
- Drug Discovery Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Malcolm Taylor
- Drug Discovery Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Ian Gilbert
- Drug Discovery Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Aileen W. McLaren
- Division of Cancer Research, Level 9, Jacqui Wood Cancer Centre, University of Dundee, Ninewells Hospital & Medical School, Dundee DD1 9SY, U.K
| | - C. Roland Wolf
- Drug Discovery Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
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Arlt VM, Henderson CJ, Wolf CR, Stiborová M, Phillips DH. The Hepatic Reductase Null (HRN™) and Reductase Conditional Null (RCN) mouse models as suitable tools to study metabolism, toxicity and carcinogenicity of environmental pollutants. Toxicol Res (Camb) 2015. [DOI: 10.1039/c4tx00116h] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
This review describes the applicability of the Hepatic Reductase Null (HRN) and Reductase Conditional Null (RCN) mouse models to study carcinogen metabolism.
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Affiliation(s)
- Volker M. Arlt
- Analytical and Environmental Sciences Division
- MRC-PHE Centre for Environment and Health
- King's College London
- London SE1 9NH
- UK
| | - Colin J. Henderson
- Division of Cancer Research
- Medical Research Institute
- Jacqui Wood Cancer Centre
- University of Dundee
- Dundee DD1 9SY
| | - C. Roland Wolf
- Division of Cancer Research
- Medical Research Institute
- Jacqui Wood Cancer Centre
- University of Dundee
- Dundee DD1 9SY
| | - Marie Stiborová
- Department of Biochemistry
- Faculty of Science
- Charles University
- 128 40 Prague 2
- Czech Republic
| | - David H. Phillips
- Analytical and Environmental Sciences Division
- MRC-PHE Centre for Environment and Health
- King's College London
- London SE1 9NH
- UK
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Du XH, Zhou XL, Cao R, Xiao P, Teng Y, Ning CB, Liu HL. FSH-induced p38-MAPK-mediated dephosphorylation at serine 727 of the signal transducer and activator of transcription 1 decreases Cyp1b1 expression in mouse granulosa cells. Cell Signal 2014; 27:6-14. [PMID: 25315223 DOI: 10.1016/j.cellsig.2014.10.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 09/26/2014] [Accepted: 10/07/2014] [Indexed: 10/24/2022]
Abstract
Most mammalian follicles undergo atresia at various stages before ovulation, and granulosa cell apoptosis is a major cause of antral follicular atresia. Estradiol is an essential mitogen for granulosa cell proliferation in vivo and inhibition of apoptosis. The estradiol-producing capacity and metabolism levels are important for follicle health, and sufficient estradiol is necessary for follicle development and ovulation. Cyp1b1, a member of the cytochrome P450 1 subfamily, is responsible for the metabolism of a wide variety of halogenated and polycyclic aromatic hydrocarbons in diverse tissues. In mouse follicles, Cyp1b1 converts estradiol to 4-hydroxyestradiol. We investigated mouse granulosa cells (MGCs) in vivo and in vitro and found that Cyp1b1 played a crucial role in estradiol metabolism in dominant follicles. Follicle-stimulating hormone (FSH) decreased estrogen metabolism by reducing Cyp1b1 mRNA and protein levels in MGCs. Furthermore, FSH regulated signal transducer and activator of transcription 1 (STAT1), a significant transcription factor of Cyp1b1, by mediating the dephosphorylation of STAT1 on serine 727 (Ser(727)) in MGCs. p38 mitogen-activated protein kinase (MAPK) may be involved in the FSH-induced dephosphorylation of STAT1 on Ser(727) in MGCs. These results suggested that FSH functions via p38 MAPK-induced dephosphorylation at Ser(727) of STAT1 to downregulate Cyp1b1 expression and maintain the estradiol levels in mouse dominant follicles.
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Affiliation(s)
- Xue-Hai Du
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, People's Republic of China
| | - Xiao-Long Zhou
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, People's Republic of China
| | - Rui Cao
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, People's Republic of China
| | - Peng Xiao
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, People's Republic of China
| | - Yun Teng
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, People's Republic of China
| | - Cai-Bo Ning
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, People's Republic of China
| | - Hong-Lin Liu
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, People's Republic of China.
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Henderson CJ, Scheer N, Wolf CR. Advances in the generation of mouse models to elucidate the pathways of drug metabolism in rodents and man. Expert Rev Clin Pharmacol 2014; 2:105-9. [DOI: 10.1586/17512433.2.2.105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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12
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Wang Q, Chen J, Ko CI, Fan Y, Carreira V, Chen Y, Xia Y, Medvedovic M, Puga A. Disruption of aryl hydrocarbon receptor homeostatic levels during embryonic stem cell differentiation alters expression of homeobox transcription factors that control cardiomyogenesis. ENVIRONMENTAL HEALTH PERSPECTIVES 2013; 121:1334-43. [PMID: 24058054 PMCID: PMC3855521 DOI: 10.1289/ehp.1307297] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Accepted: 09/19/2013] [Indexed: 05/02/2023]
Abstract
BACKGROUND The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that regulates the expression of xenobiotic detoxification genes and is a critical mediator of gene-environment interactions. Many AHR target genes identified by genome-wide gene expression profiling have morphogenetic functions, suggesting that AHR may play a role in embryonic development. OBJECTIVES To characterize the developmental functions of the AHR, we studied the consequences of AHR activation by the agonist 2,3,7,8-tetrachlorodibenzo-p-doxin (TCDD), and the result of its repression by the antagonists 6,2,4-trimethoxyflavone and CH 223191 or by short-hairpin RNA (shRNA)-mediated Ahr knockdown during spontaneous differentiation of embryonic stem (ES) cells into cardiomyocytes. METHODS We generated an AHR-positive cardiomyocyte lineage differentiated from mouse ES cells that expresses puromycin resistance and enhanced green fluorescent protein (eGFP) under the control of the Cyp1a1 (cytochrome P450 1a1) promoter. We used RNA sequencing (RNA.Seq) to analyze temporal trajectories of TCDD-dependent global gene expression in these cells during differentiation. RESULTS Activation, inhibition, and knockdown of Ahr significantly inhibited the formation of contractile cardiomyocyte nodes. Global expression analysis of AHR-positive cells showed that activation of the AHR/TCDD axis disrupted the concerted expression of genes that regulate multiple signaling pathways involved in cardiac and neural morphogenesis and differentiation, including dozens of genes encoding homeobox transcription factors and Polycomb and trithorax group proteins. CONCLUSIONS Disruption of AHR expression levels resulted in gene expression changes that perturbed cardiomyocyte differentiation. The main function of the AHR during development appears to be the coordination of a complex regulatory network responsible for attainment and maintenance of cardiovascular homeostasis.
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Furness SGB, Whelan F. The pleiotropy of dioxin toxicity--xenobiotic misappropriation of the aryl hydrocarbon receptor's alternative physiological roles. Pharmacol Ther 2009; 124:336-53. [PMID: 19781569 DOI: 10.1016/j.pharmthera.2009.09.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 09/01/2009] [Indexed: 10/20/2022]
Abstract
The aryl hydrocarbon receptor is a signal regulated transcription factor that has best been characterised as regulating the xenobiotic response to a variety of planar aromatic hydrocarbons. There is compelling evidence that it mediates most, if not all, of the toxic effects of dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin). Dioxin exposure results in a wide variety of toxic outcomes including severe wasting syndrome, chloracne, thymic involution, severe immune suppression, reduced fertility, hepatotoxicity, teratogenicity, tumour promotion and death. The pleiotropy of toxic outcomes implies the disruption of a wide range of normal physiological functions. The aryl hydrocarbon receptor has developmentally restricted expression as well as developmental defects in gene-targeted mice. It has a wide range of target genes that do not fit into the classical xenobiotic metabolising gene battery and has recently been shown to interact with NF-kappa B and the estrogen receptor. There is also evidence for its activation in the absence of exogenous ligand, all of which point to various roles outside xenobiotic metabolism. Ligands so far identified display differential activation potential with respect to receptor activity. This article addresses activities of the aryl hydrocarbon receptor that are outside the xenobiotic response. Known physiological roles are discussed as well as how their disruption contributes to the pleiotropic toxicity of TCDD.
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Affiliation(s)
- Sebastian G B Furness
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia.
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14
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Bradshaw TD, Bell DR. Relevance of the aryl hydrocarbon receptor (AhR) for clinical toxicology. Clin Toxicol (Phila) 2009; 47:632-42. [PMID: 19640236 DOI: 10.1080/15563650903140423] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
INTRODUCTION The aryl hydrocarbon receptor (AhR) is a cellular signaling molecule infamous for mediating the toxicity of dioxins and related compounds. AIM The aim of this review is to provide a background of AhR and to examine critically its role in chemical toxicity, in physiological systems, and its interaction with drugs and other compounds. TOXICITY The AhR is essential for the toxicity of dioxins and related chemicals. The AhR mediates the exquisite sensitivity of animals to dioxins, where as little as 2 ng/kg/day can yield striking adverse effects. PHYSIOLOGICAL ROLE OF AHR: The wide variety of adverse effects of dioxin argues for an important role of the AhR in a variety of physiological systems. Recent investigations have highlighted the role of AhR in the development of the brain and vasculature. DRUGS AND OTHER CHEMICAL ACTIVATORS OF AHR: The development of AhR agonists during drug development programs is sometimes inadvertent, but sometimes the target of development, and is yet further confirmation of the likely importance of AhR signaling in constitutive physiology. The presence of AhR agonists in the diet such as indolo-(3,2-b)-carbazole and 3,3'-diindolylmethane (metabolized from indole 3-carbinol), flavonoids, and sulforaphane and of endogenous activators of this signaling system such as eicosanoids, indirubin, bilirubin, cAMP, and tryptophan are suggestive that AhR activation is a normal physiological process and that it is the persistent and high-level stimulation of AhR by dioxins that is responsible for toxicity. CONCLUSIONS AhR-mediated toxicity and physiology are highly relevant to clinical toxicology and drug development.
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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]
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Cholesterol metabolism: the main pathway acting downstream of cytochrome P450 oxidoreductase in skeletal development of the limb. Mol Cell Biol 2009; 29:2716-29. [PMID: 19273610 DOI: 10.1128/mcb.01638-08] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Cytochrome P450 oxidoreductase (POR) is the obligate electron donor for all microsomal cytochrome P450 enzymes, which catalyze the metabolism of a wide spectrum of xenobiotic and endobiotic compounds. Point mutations in POR have been found recently in patients with Antley-Bixler-like syndrome, which includes limb skeletal defects. In order to study P450 function during limb and skeletal development, we deleted POR specifically in mouse limb bud mesenchyme. Forelimbs and hind limbs in conditional knockout (CKO) mice were short with thin skeletal elements and fused joints. POR deletion occurred earlier in forelimbs than in hind limbs, leading additionally to soft tissue syndactyly and loss of wrist elements and phalanges due to changes in growth, cell death, and skeletal segmentation. Transcriptional analysis of E12.5 mouse forelimb buds demonstrated the expression of P450s involved in retinoic acid, cholesterol, and arachidonic acid metabolism. Biochemical analysis of CKO limbs confirmed retinoic acid excess. In CKO limbs, expression of genes throughout the whole cholesterol biosynthetic pathway was upregulated, and cholesterol deficiency can explain most aspects of the phenotype. Thus, cellular POR-dependent cholesterol synthesis is essential during limb and skeletal development. Modulation of P450 activity could contribute to susceptibility of the embryo and developing organs to teratogenesis.
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Oesch-Bartlomowicz B, Oesch F. Role of cAMP in mediating AHR signaling. Biochem Pharmacol 2008; 77:627-41. [PMID: 19013136 DOI: 10.1016/j.bcp.2008.10.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Revised: 10/11/2008] [Accepted: 10/13/2008] [Indexed: 01/30/2023]
Abstract
Regulation of the nuclear import of many transcription factors represents a step in gene regulation which is crucial for a number of cellular processes. The aryl hydrocarbon receptor (AHR), a basic helix-loop-helix protein of the PAS (PER-ARNT-SIM) family of transcriptional regulators is a cytosol-associated and ligand-activated receptor. The environmental toxin dioxin binds with high affinity to AHR rendering it nuclear and leading to the activation of AHR sensitive genes. However, the fact, that the AHR mediates a large variety of physiological events without the involvement of any known exogenous ligand, including liver and vascular system development, maturation of the immune system, regulation of genes involved in cellular growth, cell differentiation and circadian rhythm, speaks for an important role of AHR in cell biology independent of the presence of an exogenous ligand. Different approaches were applied to study mechanism(s) which render AHR nuclear and design its function in absence of exogenous ligands. We found that AHR is sensitive to cAMP signaling mediated by cAMP-dependent protein kinase (PKA) which fundamentally differs from AHR signaling mediated by the exogenous ligand dioxin. It has been shown that PKA mediated signaling can be confined by compartmentalization of signaling components in microdomains conferring specificity to signaling by the ubiquitous second messenger cAMP. Moreover, A-kinase-anchoring proteins (AKAPs) and newly discovered cAMP receptors, Epac (exchange protein directly activated by cAMP), may give us a further chance to enter into new dimensions of cAMP signal transmissions that potentially may bring us closer to AHR physiology.
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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]
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Nguyen LP, Bradfield CA. The search for endogenous activators of the aryl hydrocarbon receptor. Chem Res Toxicol 2007; 21:102-16. [PMID: 18076143 DOI: 10.1021/tx7001965] [Citation(s) in RCA: 547] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The primary design of this perspective is to describe the major ligand classes of the aryl hydrocarbon receptor (AHR). A grander objective is to provide models that may help define the physiological activator or "endogenous ligand" of the AHR. We present evidence supporting a developmental role for the AHR and propose mechanisms by which an endogenous ligand and consequent AHR activation might be important during normal physiology and development. From this vista, we survey the known xenobiotic, endogenous, dietary, and "unconventional" activators of the AHR, including, when possible, information about their induction potency, receptor binding affinity, and potential for exposure. In light of the essential function of the AHR in embryonic development, we discuss the candidacy of each of these compounds as physiologically important activators.
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Affiliation(s)
- Linh P Nguyen
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706, USA
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Olsvik PA, Lie KK, Sæle Ø, Sanden M. Spatial transcription of CYP1A in fish liver. BMC PHYSIOLOGY 2007; 7:12. [PMID: 18053248 PMCID: PMC2238752 DOI: 10.1186/1472-6793-7-12] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Accepted: 12/05/2007] [Indexed: 11/10/2022]
Abstract
BACKGROUND The aim of this work was to study how evenly detoxifying genes are transcribed spatially in liver tissue of fish. Ten Atlantic salmon Salmo salar were intraperitoneally injected with 50 mg/kg of the strong CYP1A inducer beta-naphthoflavone and liver tissue harvested seven days later. The liver from 10 control and 10 exposed fish were split into eight sections, RNA extracted and three reference (beta-actin, elongation factor 1AB (EF1AB)) and two detoxifying genes (CYP1A and GST) quantified with real-time RT-PCR. The cellular localization of the EF1AB and CYP1A mRNA in the liver of control and beta-naphthoflavone treated fish was then determined by in situ hybridization (ISH) using EF1AB and CYP1A biotinylated oligonucleotide probes. RESULTS The study shows that genes encoding phase I and phase II conjugating enzymes are unevenly transcribed in different parts of the liver of Atlantic salmon seven days after a single-dose of beta-naphthoflavone exposure. Transcription of CYP1A and GST was higher in the middle section of the liver compared to the distal and proximal parts of the organ. The ISH data suggest that CYP1A transcription happens mainly in hepatocyte cells in the liver, and that hepatocytes in the vicinity of blood vessels respond stronger to beta-naphthoflavone than cells further away from the blood supply. CONCLUSION Overall, the qRT-PCR and ISH results reported here suggest that gene expression analysis should be performed on as pure cell populations as possible. If bulk tissue samples are to be used, one should always check how evenly the target genes are expressed in tissue sections and organs in every study.
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Affiliation(s)
- Pål A Olsvik
- National Institute of Nutrition and Seafood Research, N-5817 Bergen, Norway
| | - Kai K Lie
- National Institute of Nutrition and Seafood Research, N-5817 Bergen, Norway
| | - Øystein Sæle
- Department of Biology, University of Bergen, N-5020 Bergen, Norway
| | - Monica Sanden
- National Institute of Nutrition and Seafood Research, N-5817 Bergen, Norway
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Krzyzanowski PM, Andrade-Navarro MA. Identification of novel stem cell markers using gap analysis of gene expression data. Genome Biol 2007; 8:R193. [PMID: 17875203 PMCID: PMC2375031 DOI: 10.1186/gb-2007-8-9-r193] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Accepted: 09/17/2007] [Indexed: 01/22/2023] Open
Abstract
We describe a method for detecting marker genes in large heterogeneous collections of gene expression data. Markers are identified and characterized by the existence of demarcations in their expression values across the whole dataset, which suggest the presence of groupings of samples. We apply this method to DNA microarray data generated from 83 mouse stem cell related samples and describe 426 selected markers associated with differentiation to establish principles of stem cell evolution.
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Affiliation(s)
- Paul M Krzyzanowski
- Molecular Medicine, Ottawa Health Research Institute, 501 Smyth Road, Ottawa, Ontario, K1H 8L6, Canada
- Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada
| | - Miguel A Andrade-Navarro
- Molecular Medicine, Ottawa Health Research Institute, 501 Smyth Road, Ottawa, Ontario, K1H 8L6, Canada
- Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada
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Oesch-Bartlomowicz B, Huelster A, Wiss O, Antoniou-Lipfert P, Dietrich C, Arand M, Weiss C, Bockamp E, Oesch F. Aryl hydrocarbon receptor activation by cAMP vs. dioxin: divergent signaling pathways. Proc Natl Acad Sci U S A 2005; 102:9218-23. [PMID: 15972329 PMCID: PMC1154791 DOI: 10.1073/pnas.0503488102] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Even before the first vertebrates appeared on our planet, the aryl hydrocarbon receptor (AHR) gene was present to carry out one or more critical life functions. The vertebrate AHR then evolved to take on functions of detecting and responding to certain classes of environmental toxicants. These environmental pollutants include polycyclic aromatic hydrocarbons (e.g., benzo[a]pyrene), polyhalogenated hydrocarbons, dibenzofurans, and the most potent small-molecular-weight toxicant known, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD or dioxin). After binding of these ligands, the activated AHR translocates rapidly from the cytosol to the nucleus, where it forms a heterodimer with aryl hydrocarbon nuclear translocator, causing cellular responses that lead to toxicity, carcinogenesis, and teratogenesis. The nuclear form of the activated AHR/aryl hydrocarbon nuclear translocator complex is responsible for alterations in immune, endocrine, reproductive, developmental, cardiovascular, and central nervous system functions whose mechanisms remain poorly understood. Here, we show that the second messenger, cAMP (an endogenous mediator of hormones, neurotransmitters, and prostaglandins), activates the AHR, moving the receptor to the nucleus in some ways that are similar to and in other ways fundamentally different from AHR activation by dioxin. We suggest that this cAMP-mediated activation may reflect the true endogenous function of AHR; disruption of the cAMP-mediated activation by dioxin, binding chronically to the AHR for days, weeks, or months, might be pivotal in the mechanism of dioxin toxicity. Understanding this endogenous activation of the AHR by cAMP may help in developing methods to counteract the toxicity caused by numerous environmental and food-borne toxic chemicals that act via the AHR.
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