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Imran SJ, Vagaska B, Kriska J, Anderova M, Bortolozzi M, Gerosa G, Ferretti P, Vrzal R. Aryl Hydrocarbon Receptor (AhR)-Mediated Signaling in iPSC-Derived Human Motor Neurons. Pharmaceuticals (Basel) 2022; 15:ph15070828. [PMID: 35890127 PMCID: PMC9321538 DOI: 10.3390/ph15070828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Revised: 06/26/2022] [Accepted: 07/01/2022] [Indexed: 12/04/2022] Open
Abstract
Exposure to environmental pollutants and endogenous metabolites that induce aryl hydrocarbon receptor (AhR) expression has been suggested to affect cognitive development and, particularly in boys, also motor function. As current knowledge is based on epidemiological and animal studies, in vitro models are needed to better understand the effects of these compounds in the human nervous system at the molecular level. Here, we investigated expression of AhR pathway components and how they are regulated by AhR ligands in human motor neurons. Motor neurons generated from human induced pluripotent stem cells (hiPSCs) were characterized at the molecular level and by electrophysiology. mRNA levels of AhR target genes, CYP1A1 and CYP1B1 (cytochromes P450 1A1/1B1), and AhR signaling components were monitored in hiPSCs and in differentiated neurons following treatment with AhR ligands, 2,3,7,8,-tetrachlodibenzo-p-dioxin (TCDD), L-kynurenine (L-Kyn), and kynurenic acid (KA), by RT-qPCR. Changes in AhR cellular localization and CYP1A1 activity in neurons treated with AhR ligands were also assessed. The neurons we generated express motor neuron-specific markers and are functional. Transcript levels of CYP1B1, AhR nuclear translocators (ARNT1 and ARNT2) and the AhR repressor (AhRR) change with neuronal differentiation, being significantly higher in neurons than hiPSCs. In contrast, CYP1A1 and AhR transcript levels are slightly lower in neurons than in hiPSCs. The response to TCDD treatment differs in hiPSCs and neurons, with only the latter showing significant CYP1A1 up-regulation. In contrast, TCDD slightly up-regulates CYP1B1 mRNA in hiPSCs, but downregulates it in neurons. Comparison of the effects of different AhR ligands on AhR and some of its target genes in neurons shows that L-Kyn and KA, but not TCDD, regulate AhR expression and differently affect CYP1A1 and CYP1B1 expression. Finally, although TCDD does not significantly affect AhR transcript levels, it induces AhR protein translocation to the nucleus and increases CYP1A1 activity. This is in contrast to L-Kyn and KA, which either do not affect or reduce, respectively, CYP1A1 activity. Expression of components of the AhR signaling pathway are regulated with neuronal differentiation and are differently affected by TCDD, suggesting that pluripotent stem cells might be less sensitive to this toxin than neurons. Crucially, AhR signaling is affected differently by TCDD and other AhR ligands in human motor neurons, suggesting that they can provide a valuable tool for assessing the impact of environmental pollutants.
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Affiliation(s)
- Saima Jalil Imran
- Department of Cell Biology and Genetics, Faculty of Science, 77147 Olomouc, Czech Republic
- Stem Cells and Regenerative Medicine Section, UCL Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK; (B.V.); (P.F.)
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padua, 35128 Padua, Italy;
- Correspondence: (S.J.I.); (R.V.); Tel.: +39-498212410 (S.J.I.); +420-58-5634904 (R.V.)
| | - Barbora Vagaska
- Stem Cells and Regenerative Medicine Section, UCL Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK; (B.V.); (P.F.)
| | - Jan Kriska
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Czech Academy of Sciences, 14220 Prague, Czech Republic; (J.K.); (M.A.)
| | - Miroslava Anderova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Czech Academy of Sciences, 14220 Prague, Czech Republic; (J.K.); (M.A.)
- Second Faculty of Medicine, Charles University, 15006 Prague, Czech Republic
| | - Mario Bortolozzi
- Department of Physics and Astronomy “G. Galilei”, University of Padua, 35131 Padua, Italy;
- Veneto Institute of Molecular Medicine (VIMM), 35129 Padua, Italy
| | - Gino Gerosa
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padua, 35128 Padua, Italy;
| | - Patrizia Ferretti
- Stem Cells and Regenerative Medicine Section, UCL Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK; (B.V.); (P.F.)
| | - Radim Vrzal
- Department of Cell Biology and Genetics, Faculty of Science, 77147 Olomouc, Czech Republic
- Correspondence: (S.J.I.); (R.V.); Tel.: +39-498212410 (S.J.I.); +420-58-5634904 (R.V.)
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The Role of AhR in the Hallmarks of Brain Aging: Friend and Foe. Cells 2021; 10:cells10102729. [PMID: 34685709 PMCID: PMC8534784 DOI: 10.3390/cells10102729] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/05/2021] [Accepted: 10/10/2021] [Indexed: 12/24/2022] Open
Abstract
In recent years, aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor, has been considered to be involved in aging phenotypes across several species. This receptor is a highly conserved biosensor that is activated by numerous exogenous and endogenous molecules, including microbiota metabolites, to mediate several physiological and toxicological functions. Brain aging hallmarks, which include glial cell activation and inflammation, increased oxidative stress, mitochondrial dysfunction, and cellular senescence, increase the vulnerability of humans to various neurodegenerative diseases. Interestingly, many studies have implicated AhR signaling pathways in the aging process and longevity across several species. This review provides an overview of the impact of AhR pathways on various aging hallmarks in the brain and the implications for AhR signaling as a mechanism in regulating aging-related diseases of the brain. We also explore how the nature of AhR ligands determines the outcomes of several signaling pathways in brain aging processes.
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Desaulniers D, Vasseur P, Jacobs A, Aguila MC, Ertych N, Jacobs MN. Integration of Epigenetic Mechanisms into Non-Genotoxic Carcinogenicity Hazard Assessment: Focus on DNA Methylation and Histone Modifications. Int J Mol Sci 2021; 22:10969. [PMID: 34681626 PMCID: PMC8535778 DOI: 10.3390/ijms222010969] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/30/2021] [Accepted: 10/04/2021] [Indexed: 12/15/2022] Open
Abstract
Epigenetics involves a series of mechanisms that entail histone and DNA covalent modifications and non-coding RNAs, and that collectively contribute to programing cell functions and differentiation. Epigenetic anomalies and DNA mutations are co-drivers of cellular dysfunctions, including carcinogenesis. Alterations of the epigenetic system occur in cancers whether the initial carcinogenic events are from genotoxic (GTxC) or non-genotoxic (NGTxC) carcinogens. NGTxC are not inherently DNA reactive, they do not have a unifying mode of action and as yet there are no regulatory test guidelines addressing mechanisms of NGTxC. To fil this gap, the Test Guideline Programme of the Organisation for Economic Cooperation and Development is developing a framework for an integrated approach for the testing and assessment (IATA) of NGTxC and is considering assays that address key events of cancer hallmarks. Here, with the intent of better understanding the applicability of epigenetic assays in chemical carcinogenicity assessment, we focus on DNA methylation and histone modifications and review: (1) epigenetic mechanisms contributing to carcinogenesis, (2) epigenetic mechanisms altered following exposure to arsenic, nickel, or phenobarbital in order to identify common carcinogen-specific mechanisms, (3) characteristics of a series of epigenetic assay types, and (4) epigenetic assay validation needs in the context of chemical hazard assessment. As a key component of numerous NGTxC mechanisms of action, epigenetic assays included in IATA assay combinations can contribute to improved chemical carcinogen identification for the better protection of public health.
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Affiliation(s)
- Daniel Desaulniers
- Environmental Health Sciences and Research Bureau, Hazard Identification Division, Health Canada, AL:2203B, Ottawa, ON K1A 0K9, Canada
| | - Paule Vasseur
- CNRS, LIEC, Université de Lorraine, 57070 Metz, France;
| | - Abigail Jacobs
- Independent at the Time of Publication, Previously US Food and Drug Administration, Rockville, MD 20852, USA;
| | - M. Cecilia Aguila
- Toxicology Team, Division of Human Food Safety, Center for Veterinary Medicine, US Food and Drug Administration, Department of Health and Human Services, Rockville, MD 20852, USA;
| | - Norman Ertych
- German Centre for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment, Diedersdorfer Weg 1, 12277 Berlin, Germany;
| | - Miriam N. Jacobs
- Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton OX11 0RQ, UK;
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Lopez-Rodriguez D, Franssen D, Heger S, Parent AS. Endocrine-disrupting chemicals and their effects on puberty. Best Pract Res Clin Endocrinol Metab 2021; 35:101579. [PMID: 34563408 DOI: 10.1016/j.beem.2021.101579] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Sexual maturation in humans is characterized by a unique individual variability. Pubertal onset is a highly heritable polygenic trait but it is also affected by environmental factors such as obesity or endocrine disrupting chemicals. The last 30 years have been marked by a constant secular trend toward earlier age at onset of puberty in girls and boys around the world. More recent data, although more disputed, suggest an increased incidence in idiopathic central precocious puberty. Such trends point to a role for environmental factors in pubertal changes. Animal data suggest that the GnRH-neuronal network is highly sensitive to endocrine disruption during development. This review focuses on the most recent data regarding secular trend in pubertal timing as well as potential new epigenetic mechanisms explaining the developmental and transgenerational effects of endocrine disrupting chemicals on pubertal timing.
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Affiliation(s)
| | - Delphine Franssen
- GIGA Neurosciences, Neuroendocrinology Unit, University of Liège, Belgium
| | - Sabine Heger
- Children's Hospital Bult, Janusz-Korczak-Allee 12, 30173, Hannover, Germany
| | - Anne-Simone Parent
- GIGA Neurosciences, Neuroendocrinology Unit, University of Liège, Belgium; Department of Pediatrics, University Hospital Liège, Belgium.
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Influence of the Aryl Hydrocarbon Receptor Activating Environmental Pollutants on Autism Spectrum Disorder. Int J Mol Sci 2021; 22:ijms22179258. [PMID: 34502168 PMCID: PMC8431328 DOI: 10.3390/ijms22179258] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/22/2021] [Accepted: 06/28/2021] [Indexed: 02/07/2023] Open
Abstract
Autism spectrum disorder (ASD) is an umbrella term that includes many different disorders that affect the development, communication, and behavior of an individual. Prevalence of ASD has risen exponentially in the past couple of decades. ASD has a complex etiology and traditionally recognized risk factors only account for a small percentage of incidence of the disorder. Recent studies have examined factors beyond the conventional risk factors (e.g., environmental pollution). There has been an increase in air pollution since the beginning of industrialization. Most environmental pollutants cause toxicities through activation of several cellular receptors, such as the aryl hydrocarbon receptor (AhR)/cytochrome P450 (CYPs) pathway. There is little research on the involvement of AhR in contributing to ASD. Although a few reviews have discussed and addressed the link between increased prevalence of ASD and exposure to environmental pollutants, the mechanism governing this effect, specifically the role of AhR in ASD development and the molecular mechanisms involved, have not been discussed or reviewed before. This article reviews the state of knowledge regarding the impact of the AhR/CYP pathway modulation upon exposure to environmental pollutants on ASD risk, incidence, and development. It also explores the molecular mechanisms involved, such as epigenesis and polymorphism. In addition, the review explores possible new AhR-mediated mechanisms of several drugs used for treatment of ASD, such as sulforaphane, resveratrol, haloperidol, and metformin.
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Wang Y, Hu C, Fang T, Jin Y, Wu R. Perspective on prenatal polychlorinated biphenyl exposure and the development of the progeny nervous system (Review). Int J Mol Med 2021; 48:150. [PMID: 34132363 PMCID: PMC8219518 DOI: 10.3892/ijmm.2021.4983] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 05/26/2021] [Indexed: 02/05/2023] Open
Abstract
The developmental origins of health and disease concept illustrates that exposure in early life to various factors may affect the offspring's long-term susceptibility to disease. During development, the nervous system is sensitive and vulnerable to the environmental insults. Polychlorinated biphenyls (PCBs), which are divided into dioxin-like (DL-PCBs) and non-dioxin-like PCBs (NDL-PCBs), are synthetic persistent environmental endocrine-disrupting chemicals. The toxicological mechanisms of DL-PCBs have been associated with the activation of the aryl hydrocarbon receptor and NDL-PCBs have been associated with ryanodine receptor-mediated calcium ion channels, which affect neuronal migration, promote dendritic growth and alter neuronal connectivity. In addition, PCB accumulation in the placenta destroys the fetal placental unit and affects endocrine function, particularly thyroid hormones and the dopaminergic system, leading to neuroendocrine disorders. However, epidemiological investigations have not achieved a consistent result in different study cohorts. The present review summarizes the epidemiological differences and possible mechanisms of the effects of intrauterine PCB exposure on neurological development.
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Affiliation(s)
- Yinfeng Wang
- Department of Gynecology and Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310006, P.R. China
| | - Changchang Hu
- Department of Gynecology and Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310006, P.R. China
| | - Tao Fang
- Department of Gynecology and Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310006, P.R. China
| | - Yang Jin
- Department of Gynecology and Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310006, P.R. China
| | - Ruijin Wu
- Department of Gynecology and Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310006, P.R. China
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Lopez-Rodriguez D, Franssen D, Bakker J, Lomniczi A, Parent AS. Cellular and molecular features of EDC exposure: consequences for the GnRH network. Nat Rev Endocrinol 2021; 17:83-96. [PMID: 33288917 DOI: 10.1038/s41574-020-00436-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/16/2020] [Indexed: 12/12/2022]
Abstract
The onset of puberty and the female ovulatory cycle are important developmental milestones of the reproductive system. These processes are controlled by a tightly organized network of neurotransmitters and neuropeptides, as well as genetic, epigenetic and hormonal factors, which ultimately drive the pulsatile secretion of gonadotropin-releasing hormone. They also strongly depend on organizational processes that take place during fetal and early postnatal life. Therefore, exposure to environmental pollutants such as endocrine-disrupting chemicals (EDCs) during critical periods of development can result in altered brain development, delayed or advanced puberty and long-term reproductive consequences, such as impaired fertility. The gonads and peripheral organs are targets of EDCs, and research from the past few years suggests that the organization of the neuroendocrine control of reproduction is also sensitive to environmental cues and disruption. Among other mechanisms, EDCs interfere with the action of steroidal and non-steroidal receptors, and alter enzymatic, metabolic and epigenetic pathways during development. In this Review, we discuss the cellular and molecular consequences of perinatal exposure (mostly in rodents) to representative EDCs with a focus on the neuroendocrine control of reproduction, pubertal timing and the female ovulatory cycle.
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Affiliation(s)
| | - Delphine Franssen
- Neuroendocrinology Unit, GIGA Neurosciences, University of Liège, Liège, Belgium
| | - Julie Bakker
- Neuroendocrinology Unit, GIGA Neurosciences, University of Liège, Liège, Belgium
| | - Alejandro Lomniczi
- Division of Neuroscience, Oregon National Primate Research Center (ONPRC), OHSU, OR, USA
| | - Anne-Simone Parent
- Neuroendocrinology Unit, GIGA Neurosciences, University of Liège, Liège, Belgium.
- Department of Pediatrics, University Hospital Liège, Liège, Belgium.
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Desai M, Han G, Li T, Ross MG. Programmed Epigenetic DNA Methylation-Mediated Reduced Neuroprogenitor Cell Proliferation and Differentiation in Small-for-Gestational-Age Offspring. Neuroscience 2019; 412:60-71. [PMID: 31153962 DOI: 10.1016/j.neuroscience.2019.05.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 05/01/2019] [Accepted: 05/22/2019] [Indexed: 12/28/2022]
Abstract
Small-for-gestational age (SGA) human newborns have an increased risk of hyperphagia and obesity, as well as a spectrum of neurologic and neurobehavioral abnormalities. We have shown that the SGA hypothalamic (appetite regulatory site) neuroprogenitor cells (NPCs) exhibit reduced proliferation and neuronal differentiation. DNA methylation (DNA methyltransferase; DNMT1) regulates neurogenesis by maintaining NPC proliferation and suppressing premature differentiation. Once differentiation ensues, DNMT1 preferentially promotes neuronal and inhibits astroglial fate. We hypothesized that the programmed dysfunction of NPC proliferation and differentiation in SGA offspring is epigenetically mediated via DNMT1. Pregnant rats received either ad libitum food (Control) or were 50% food-restricted to create SGA offspring. Primary hypothalamic NPCs from 1 day old SGA and Controls newborns were cultured and transfected with nonspecific or DNMT1-specific siRNA. NPC proliferation and protein expression of specific markers of NPC (nestin), neuroproliferative transcription factor (Hes1), neurons (Tuj1) and astrocytes (GFAP) were determined. Under basal conditions, SGA NPCs exhibited decreased DNMT1 and reduced proliferation and differentiation, as compared to Controls. In both SGA and Controls, DNMT1 siRNA in complete media inhibited NPC proliferation, consistent with reduced expression of nestin and Hes1. In differentiation media, DNMT1 siRNA decreased expression of Tuj1 but increased GFAP. In vivo data replicated these findings. In SGA offspring, impaired neurogenesis is epigenetically mediated, in part, via reduction in DNMT1 expression and suppression of Hes1 resulting in NPC differentiation. It is likely that the maturation of regions beyond the hypothalamus (e.g., cerebral cortex, hippocampus) may be impacted, contributing to poor cognitive and neurobehavioral competency in SGA offspring.
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Affiliation(s)
- Mina Desai
- Perinatal Research Laboratory, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Department of Obstetrics and Gynecology, Torrance, CA, USA; Department of Obstetrics and Gynecology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
| | - Guang Han
- Perinatal Research Laboratory, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Department of Obstetrics and Gynecology, Torrance, CA, USA
| | - Tie Li
- Perinatal Research Laboratory, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Department of Obstetrics and Gynecology, Torrance, CA, USA
| | - Michael G Ross
- Perinatal Research Laboratory, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Department of Obstetrics and Gynecology, Torrance, CA, USA; Department of Obstetrics and Gynecology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA; Department of Obstetrics and Gynecology, Charles R. Drew University, Los Angeles, CA, USA
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Guo Z, Xie HQ, Zhang P, Luo Y, Xu T, Liu Y, Fu H, Xu L, Valsami-Jones E, Boksa P, Zhao B. Dioxins as potential risk factors for autism spectrum disorder. ENVIRONMENT INTERNATIONAL 2018; 121:906-915. [PMID: 30347373 DOI: 10.1016/j.envint.2018.10.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 10/14/2018] [Accepted: 10/14/2018] [Indexed: 06/08/2023]
Abstract
Autism spectrum disorder (ASD) has emerged as a major public health concern due to its fast-growing prevalence in recent decades. Environmental factors are thought to contribute substantially to the variance in ASD. Interest in environmental toxins as causes of ASD has arisen due to the high sensitivity of the developing human brain to toxic chemicals, particularly to dioxin and certain dioxin-like compounds (dioxins). As a group of typical persistent organic pollutants, dioxins have been found to exert adverse effects on human brain development. In this paper, we review the evidence for association of exposure to dioxins with neurodevelopmental abnormalities related to ASD based on both human epidemiological and animal studies. It has been documented that exposure to dioxins during critical developmental periods increased risk for ASD. This notion has been demonstrated in different populations exposed to high or background level of dioxins. Furthermore, the effects and mechanisms of action of dioxins relevant to the pathophysiology and pathogenesis of ASD are summarized, describing potential underlying mechanisms linking dioxin exposure with ASD onset. Further studies focusing on effects of prenatal/perinatal exposure to individual dioxin congeners or to mixtures of dioxins on ASD-associated behavioral and neurobiological consequences in animal models, and on the mechanisms of actions of dioxins, are needed in order to better understand how dioxin exposure might contribute to increased risk for ASD.
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Affiliation(s)
- Zhiling Guo
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Heidi Qunhui Xie
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peng Zhang
- University of Birmingham, School of Geography, Earth and Environmental Sciences, Birmingham B15 2TT, UK
| | - Yali Luo
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tuan Xu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yiyun Liu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hualing Fu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Li Xu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Eugenia Valsami-Jones
- University of Birmingham, School of Geography, Earth and Environmental Sciences, Birmingham B15 2TT, UK
| | - Patricia Boksa
- Department of Psychiatry, McGill University, 6875 LaSalle Boulevard, Montreal, QC, Canada; Neuroscience Division, Douglas Mental Health University Institute, Montreal, QC, Canada.
| | - Bin Zhao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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The Aryl Hydrocarbon Receptor and the Nervous System. Int J Mol Sci 2018; 19:ijms19092504. [PMID: 30149528 PMCID: PMC6163841 DOI: 10.3390/ijms19092504] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 08/17/2018] [Accepted: 08/21/2018] [Indexed: 12/12/2022] Open
Abstract
The aryl hydrocarbon receptor (or AhR) is a cytoplasmic receptor of pollutants. It translocates into the nucleus upon binding to its ligands, and forms a heterodimer with ARNT (AhR nuclear translocator). The heterodimer is a transcription factor, which regulates the transcription of xenobiotic metabolizing enzymes. Expressed in many cells in vertebrates, it is mostly present in neuronal cell types in invertebrates, where it regulates dendritic morphology or feeding behavior. Surprisingly, few investigations have been conducted to unravel the function of the AhR in the central or peripheral nervous systems of vertebrates. In this review, we will present how the AhR regulates neural functions in both invertebrates and vertebrates as deduced mainly from the effects of xenobiotics. We will introduce some of the molecular mechanisms triggered by the well-known AhR ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), which impact on neuronal proliferation, differentiation, and survival. Finally, we will point out the common features found in mice that are exposed to pollutants, and in AhR knockout mice.
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11
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Aluru N, Karchner SI, Krick KS, Zhu W, Liu J. Role of DNA methylation in altered gene expression patterns in adult zebrafish ( Danio rerio) exposed to 3, 3', 4, 4', 5-pentachlorobiphenyl (PCB 126). ENVIRONMENTAL EPIGENETICS 2018; 4:dvy005. [PMID: 29686887 PMCID: PMC5905506 DOI: 10.1093/eep/dvy005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 02/09/2018] [Accepted: 03/08/2018] [Indexed: 05/08/2023]
Abstract
There is growing evidence that environmental toxicants can affect various physiological processes by altering DNA methylation patterns. However, very little is known about the impact of toxicant-induced DNA methylation changes on gene expression patterns. The objective of this study was to determine the genome-wide changes in DNA methylation concomitant with altered gene expression patterns in response to 3, 3', 4, 4', 5-pentachlorobiphenyl (PCB126) exposure. We used PCB126 as a model environmental chemical because the mechanism of action is well-characterized, involving activation of aryl hydrocarbon receptor, a ligand-activated transcription factor. Adult zebrafish were exposed to 10 nM PCB126 for 24 h (water-borne exposure) and brain and liver tissues were sampled at 7 days post-exposure in order to capture both primary and secondary changes in DNA methylation and gene expression. We used enhanced Reduced Representation Bisulfite Sequencing and RNAseq to quantify DNA methylation and gene expression, respectively. Enhanced reduced representation bisulfite sequencing analysis revealed 573 and 481 differentially methylated regions in the liver and brain, respectively. Most of the differentially methylated regions are located more than 10 kilobases upstream of transcriptional start sites of the nearest neighboring genes. Gene Ontology analysis of these genes showed that they belong to diverse physiological pathways including development, metabolic processes and regeneration. RNAseq results revealed differential expression of genes related to xenobiotic metabolism, oxidative stress and energy metabolism in response to polychlorinated biphenyl exposure. There was very little correlation between differentially methylated regions and differentially expressed genes suggesting that the relationship between methylation and gene expression is dynamic and complex, involving multiple layers of regulation.
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Affiliation(s)
- Neelakanteswar Aluru
- Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
- Correspondence address. Department of Biology, Woods Hole Oceanographic Institution, 45 Water Street, Woods Hole, MA 02543, USA. Tel: 508-289-3607; Fax: 508-457-2134; E-mail:
| | - Sibel I Karchner
- Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Keegan S Krick
- Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Wei Zhu
- CAS Key Laboratory of Genomic Sciences and Information, Collaborative Innovation Center of Genetics and Development, Beijing Institute of Genomics, CAS, Beijing 100101, China
| | - Jiang Liu
- CAS Key Laboratory of Genomic Sciences and Information, Collaborative Innovation Center of Genetics and Development, Beijing Institute of Genomics, CAS, Beijing 100101, China
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12
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Walker DM, Gore AC. Epigenetic impacts of endocrine disruptors in the brain. Front Neuroendocrinol 2017; 44:1-26. [PMID: 27663243 PMCID: PMC5429819 DOI: 10.1016/j.yfrne.2016.09.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/05/2016] [Accepted: 09/14/2016] [Indexed: 12/12/2022]
Abstract
The acquisition of reproductive competence is organized and activated by steroid hormones acting upon the hypothalamus during critical windows of development. This review describes the potential role of epigenetic processes, particularly DNA methylation, in the regulation of sexual differentiation of the hypothalamus by hormones. We examine disruption of these processes by endocrine-disrupting chemicals (EDCs) in an age-, sex-, and region-specific manner, focusing on how perinatal EDCs act through epigenetic mechanisms to reprogram DNA methylation and sex steroid hormone receptor expression throughout life. These receptors are necessary for brain sexual differentiation and their altered expression may underlie disrupted reproductive physiology and behavior. Finally, we review the literature on histone modifications and non-coding RNA involvement in brain sexual differentiation and their perturbation by EDCs. By putting these data into a sex and developmental context we conclude that perinatal EDC exposure alters the developmental trajectory of reproductive neuroendocrine systems in a sex-specific manner.
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Affiliation(s)
- Deena M Walker
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1065, New York, NY 10029, USA.
| | - Andrea C Gore
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, and The University of Texas at Austin, Austin, TX 78712, USA; Institute for Neuroscience, The University of Texas at Austin, Austin, TX 78712, USA
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13
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Desaulniers D, Cooke GM, Leingartner K, Soumano K, Cole J, Yang J, Wade M, Yagminas A. Effects of Postnatal Exposure to a Mixture of Polychlorinated Biphenyls, p,p′-dichlorodiphenyltrichloroethane, and p-p′-dichlorodiphenyldichloroethene in Prepubertal and Adult Female Sprague-Dawley Rats. Int J Toxicol 2016; 24:111-27. [PMID: 16036770 DOI: 10.1080/10915810590936382] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The postnatal period is a critical phase of development and a time during which humans are exposed to higher levels of persistent organic pollutants (POPs), than during subsequent periods of life. There is a paucity of information describing effects of postnatal exposure to environmentally relevant mixtures of POPs, such as polychlorinated biphenyls (PCBs), p,p′-dichlorodiphenyltrichloroethane (DDT), and p,p′-dichlorodiphenyldichloroethene (DDE). To provide data useful for the risk assessment of postnatal exposure to POPs, mixtures containing 19 PCBs, DDT, and DDE were prepared according to their concentrations previously measured in the milk of Canadian women, and dose-response effects were tested on the proliferation of MCF7-E3 cells in vitro, and in vivo experiments. Female neonates were exposed by gavage at postnatal days (PNDs) 1, 5, 10, 15, and 20 with dosages equivalent to 10, 100, and 1000 times the estimated human exposure level over the first 24 days of life. The MCF7-E3 cells showed a 227% increase in the AlamarBlue proliferation index, suggesting estrogen-like properties of the mixture, but this was not confirmed in vivo, given the absence of uterotrophic effects at PND21. An increase (511%) in hepatic ethoxyresorufin- o-deethylase activity at the dose 100 × was the most sensitive endpoint among those measured at PND21 (organ weight, mammary gland and ovarian morphometry, hepatic enzyme inductions, serum thyroxine and pituitary hormones). In liver samples from older female rats (previously involved in a mammary tumor study [Desaulniers et al., Toxicol. Sci. 75:468–480, 2001]), hepatic metabolism of 14C-estradiol-17 β (E2) at PND55 to PND62 was significantly higher in the 1000 × compared to the control group, but hepatic detoxification enzyme activities had already returned to control values. The production of hepatic 2-hydroxy-E2 decreased, whereas that of estrone increased with age. In conclusion, the smallest dose of the mixture to induce significant effects was 100×, and mixture-induced changes in the hepatic metabolism of estrogens might be a sensitive indicator of persistent effects.
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Affiliation(s)
- Daniel Desaulniers
- Environmental Health Sciences Bureau, Healthy Environment and Consumer Safety Branch, Health Canada, Ottawa, Ontario, Canada.
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14
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Desaulniers D, Cummings-Lorbetskie C, Li N, Xiao GH, Marro L, Khan N, Leingartner K. Sodium bisulfite pyrosequencing revealed that developmental exposure to environmental contaminant mixtures does not affect DNA methylation of DNA repeats in Sprague-Dawley rats. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2016; 80:32-52. [PMID: 27905861 DOI: 10.1080/15287394.2016.1231644] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 08/29/2016] [Indexed: 06/06/2023]
Abstract
Hypomethylation of DNA repeats has been linked to diseases and cancer predisposition. Human studies suggest that higher blood concentrations of environmental contaminants (EC) correlate with levels of hypomethylation of DNA repeats in blood. The objective of this study was to examine the effect of in utero and/or lactational exposure to EC on the methylation of DNA repeats (LINE-1 and identifier element) in Sprague-Dawley rat pups at birth, at postnatal day (PND) 21, and in adulthood (PND78-86). From gestation day 0 to PND20, dams were exposed to a mixture "M" of polychlorinated biphenyls (PCB), pesticides, and methylmercury (MeHg), at 0.5 or 1 mg/kg/d (0.5M and M). At birth, some control (C) and M litters were cross-fostered to create the following in utero/postnatal exposure groups: C/C, M/C, C/M, M/M. Additional dams received 1.8 ng/kg/d of a mixture of aryl-hydrocarbon receptor (AhR) agonists (non-ortho-PCB, PC-dibenzodioxins, and PC-dibenzofurans) without or with 0.5M (0.5MAhR). Measurements of EC residue levels confirmed differences in their accumulation across treatments, age, and tissues. Although induction of hepatic detoxification enzyme activities (cytochrome P-450) demonstrated biological effects of treatments, the assessment of methylation in DNA repeats by sodium bisulfite pyrosequencing of liver, spleen, and thymus samples revealed no marked treatment-related effects but significant tissue- and age-related methylation differences. Further studies are required to determine whether absence of significant observable treatment effects on methylation of DNA repeats in the rat relate to tissue, strain, or species differences.
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Affiliation(s)
- Daniel Desaulniers
- a Health Canada, Healthy Environments and Consumer Safety Branch, Environmental Health Sciences and Research Bureau , Ottawa , Ontario , Canada
| | - Cathy Cummings-Lorbetskie
- a Health Canada, Healthy Environments and Consumer Safety Branch, Environmental Health Sciences and Research Bureau , Ottawa , Ontario , Canada
| | - Nanqin Li
- a Health Canada, Healthy Environments and Consumer Safety Branch, Environmental Health Sciences and Research Bureau , Ottawa , Ontario , Canada
| | - Gong-Hua Xiao
- a Health Canada, Healthy Environments and Consumer Safety Branch, Environmental Health Sciences and Research Bureau , Ottawa , Ontario , Canada
| | - Leonora Marro
- a Health Canada, Healthy Environments and Consumer Safety Branch, Environmental Health Sciences and Research Bureau , Ottawa , Ontario , Canada
| | - Nasrin Khan
- a Health Canada, Healthy Environments and Consumer Safety Branch, Environmental Health Sciences and Research Bureau , Ottawa , Ontario , Canada
| | - Karen Leingartner
- a Health Canada, Healthy Environments and Consumer Safety Branch, Environmental Health Sciences and Research Bureau , Ottawa , Ontario , Canada
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15
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Amenya HZ, Tohyama C, Ohsako S. Dioxin induces Ahr-dependent robust DNA demethylation of the Cyp1a1 promoter via Tdg in the mouse liver. Sci Rep 2016; 6:34989. [PMID: 27713569 PMCID: PMC5054525 DOI: 10.1038/srep34989] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 09/22/2016] [Indexed: 12/24/2022] Open
Abstract
The aryl hydrocarbon receptor (Ahr) is a highly conserved nuclear receptor that plays an important role in the manifestation of toxicity induced by polycyclic aromatic hydrocarbons. As a xenobiotic sensor, Ahr is involved in chemical biotransformation through activation of drug metabolizing enzymes. The activated Ahr cooperates with coactivator complexes to induce epigenetic modifications at target genes. Thus, it is conceivable that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a potent Ahr ligand, may elicit robust epigenetic changes in vivo at the Ahr target gene cytochrome P450 1a1 (Cyp1a1). A single dose of TCDD administered to adult mice induced Ahr-dependent CpG hypomethylation, changes in histone modifications, and thymine DNA glycosylase (Tdg) recruitment at the Cyp1a1 promoter in the liver within 24 hrs. These epigenetic changes persisted until 40 days post-TCDD treatment and there was Cyp1a1 mRNA hyperinduction upon repeat administration of TCDD at this time-point. Our demethylation assay using siRNA knockdown and an in vitro methylated plasmid showed that Ahr, Tdg, and the ten-eleven translocation methyldioxygenases Tet2 and Tet3 are required for the TCDD-induced DNA demethylation. These results provide novel evidence of Ahr-driven active DNA demethylation and epigenetic memory. The epigenetic alterations influence response to subsequent chemical exposure and imply an adaptive mechanism to xenobiotic stress.
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Affiliation(s)
- Hesbon Z Amenya
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Chiharu Tohyama
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School and Faculty of Medicine, The University of Tokyo, Tokyo, Japan.,Experimental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan
| | - Seiichiroh Ohsako
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
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Cariaga-Martinez A, Saiz-Ruiz J, Alelú-Paz R. From Linkage Studies to Epigenetics: What We Know and What We Need to Know in the Neurobiology of Schizophrenia. Front Neurosci 2016; 10:202. [PMID: 27242407 PMCID: PMC4862989 DOI: 10.3389/fnins.2016.00202] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 04/25/2016] [Indexed: 01/15/2023] Open
Abstract
Schizophrenia is a complex psychiatric disorder characterized by the presence of positive, negative, and cognitive symptoms that lacks a unifying neuropathology. In the present paper, we will review the current understanding of molecular dysregulation in schizophrenia, including genetic and epigenetic studies. In relation to the latter, basic research suggests that normal cognition is regulated by epigenetic mechanisms and its dysfunction occurs upon epigenetic misregulation, providing new insights into missing heritability of complex psychiatric diseases, referring to the discrepancy between epidemiological heritability and the proportion of phenotypic variation explained by DNA sequence difference. In schizophrenia the absence of consistently replicated genetic effects together with evidence for lasting changes in gene expression after environmental exposures suggest a role of epigenetic mechanisms. In this review we will focus on epigenetic modifications as a key mechanism through which environmental factors interact with individual's genetic constitution to affect risk of psychotic conditions throughout life.
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Affiliation(s)
- Ariel Cariaga-Martinez
- Laboratory for Neuroscience of Mental Disorders Elena Pessino, Department of Medicine and Medical Specialties, School of Medicine, Alcalá University Madrid, Spain
| | - Jerónimo Saiz-Ruiz
- Department of Psychiatry, Ramón y Cajal Hospital, IRYCISMadrid, Spain; Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM)Madrid, Spain
| | - Raúl Alelú-Paz
- Laboratory for Neuroscience of Mental Disorders Elena Pessino, Department of Medicine and Medical Specialties, School of Medicine, Alcalá UniversityMadrid, Spain; Department of Psychiatry, Ramón y Cajal Hospital, IRYCISMadrid, Spain
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17
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Keil KP, Lein PJ. DNA methylation: a mechanism linking environmental chemical exposures to risk of autism spectrum disorders? ENVIRONMENTAL EPIGENETICS 2016; 2:dvv012. [PMID: 27158529 PMCID: PMC4856164 DOI: 10.1093/eep/dvv012] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
There is now compelling evidence that gene by environment interactions are important in the etiology of autism spectrum disorders (ASDs). However, the mechanisms by which environmental factors interact with genetic susceptibilities to confer individual risk for ASD remain a significant knowledge gap in the field. The epigenome, and in particular DNA methylation, is a critical gene expression regulatory mechanism in normal and pathogenic brain development. DNA methylation can be influenced by environmental factors such as diet, hormones, stress, drugs, or exposure to environmental chemicals, suggesting that environmental factors may contribute to adverse neurodevelopmental outcomes of relevance to ASD via effects on DNA methylation in the developing brain. In this review, we describe epidemiological and experimental evidence implicating altered DNA methylation as a potential mechanism by which environmental chemicals confer risk for ASD, using polychlorinated biphenyls (PCBs), lead, and bisphenol A (BPA) as examples. Understanding how environmental chemical exposures influence DNA methylation and how these epigenetic changes modulate the risk and/or severity of ASD will not only provide mechanistic insight regarding gene-environment interactions of relevance to ASD but may also suggest potential intervention strategies for these and potentially other neurodevelopmental disorders.
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Affiliation(s)
- Kimberly P. Keil
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Pamela J. Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA
- *Correspondence address. Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA. Tel:
(530) 752-1970
; Fax:
(530) 752-7690
; E-mail:
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18
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Ma J, Chen X, Liu Y, Xie Q, Sun Y, Chen J, Leng L, Yan H, Zhao B, Tang N. Ancestral TCDD exposure promotes epigenetic transgenerational inheritance of imprinted gene Igf2: Methylation status and DNMTs. Toxicol Appl Pharmacol 2015; 289:193-202. [PMID: 26455773 DOI: 10.1016/j.taap.2015.09.024] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 09/25/2015] [Accepted: 09/28/2015] [Indexed: 11/22/2022]
Abstract
Ancestral TCDD exposure could induce epigenetic transgenerational phenotypes, which may be mediated in part by imprinted gene inheritance. The aim of our study was to evaluate the transgenerational effects of ancestral TCDD exposure on the imprinted gene insulin-like growth factor-2 (Igf2) in rat somatic tissue. TCDD was administered daily by oral gavage to groups of F0 pregnant SD rats at dose levels of 0 (control), 200 or 800 ng/kg bw during gestation day 8-14. Animal transgenerational model of ancestral exposure to TCDD was carefully built, avoiding sibling inbreeding. Hepatic Igf2 expression of the TCDD male progeny was decreased concomitantly with hepatic damage and increased activities of serum hepatic enzymes both in the F1 and F3 generation. Imprinted Control Region (ICR) of Igf2 manifested a hypermethylated pattern, whereas methylation status in the Differentially Methylated Region 2 (DMR2) showed a hypomethylated manner in the F1 generation. These epigenetic alterations in these two regions maintained similar trends in the F3 generation. Meanwhile, the expressions of DNA methyltransferases (DNMT1, DNMT3A and DNMT3B) changed in a non-monotonic manner both in the F1 and F3 generation. This study provides evidence that ancestral TCDD exposure may promote epigenetic transgenerational alterations of imprinted gene Igf2 in adult somatic tissue.
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Affiliation(s)
- Jing Ma
- Department of Occupational and Environmental Health, School of Public Health, Tianjin Medical University, Tianjin 300070, China
| | - Xi Chen
- Department of Occupational and Environmental Health, School of Public Health, Tianjin Medical University, Tianjin 300070, China
| | - Yanan Liu
- Department of Occupational and Environmental Health, School of Public Health, Tianjin Medical University, Tianjin 300070, China
| | - Qunhui Xie
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yawen Sun
- Department of Occupational and Environmental Health, School of Public Health, Tianjin Medical University, Tianjin 300070, China
| | - Jingshan Chen
- Department of Occupational and Environmental Health, School of Public Health, Tianjin Medical University, Tianjin 300070, China
| | - Ling Leng
- Department of Occupational and Environmental Health, School of Public Health, Tianjin Medical University, Tianjin 300070, China
| | - Huan Yan
- Department of Occupational and Environmental Health, School of Public Health, Tianjin Medical University, Tianjin 300070, China
| | - Bin Zhao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
| | - Naijun Tang
- Department of Occupational and Environmental Health, School of Public Health, Tianjin Medical University, Tianjin 300070, China.
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19
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Gore AC, Chappell VA, Fenton SE, Flaws JA, Nadal A, Prins GS, Toppari J, Zoeller RT. EDC-2: The Endocrine Society's Second Scientific Statement on Endocrine-Disrupting Chemicals. Endocr Rev 2015; 36:E1-E150. [PMID: 26544531 PMCID: PMC4702494 DOI: 10.1210/er.2015-1010] [Citation(s) in RCA: 1257] [Impact Index Per Article: 139.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 09/01/2015] [Indexed: 02/06/2023]
Abstract
The Endocrine Society's first Scientific Statement in 2009 provided a wake-up call to the scientific community about how environmental endocrine-disrupting chemicals (EDCs) affect health and disease. Five years later, a substantially larger body of literature has solidified our understanding of plausible mechanisms underlying EDC actions and how exposures in animals and humans-especially during development-may lay the foundations for disease later in life. At this point in history, we have much stronger knowledge about how EDCs alter gene-environment interactions via physiological, cellular, molecular, and epigenetic changes, thereby producing effects in exposed individuals as well as their descendants. Causal links between exposure and manifestation of disease are substantiated by experimental animal models and are consistent with correlative epidemiological data in humans. There are several caveats because differences in how experimental animal work is conducted can lead to difficulties in drawing broad conclusions, and we must continue to be cautious about inferring causality in humans. In this second Scientific Statement, we reviewed the literature on a subset of topics for which the translational evidence is strongest: 1) obesity and diabetes; 2) female reproduction; 3) male reproduction; 4) hormone-sensitive cancers in females; 5) prostate; 6) thyroid; and 7) neurodevelopment and neuroendocrine systems. Our inclusion criteria for studies were those conducted predominantly in the past 5 years deemed to be of high quality based on appropriate negative and positive control groups or populations, adequate sample size and experimental design, and mammalian animal studies with exposure levels in a range that was relevant to humans. We also focused on studies using the developmental origins of health and disease model. No report was excluded based on a positive or negative effect of the EDC exposure. The bulk of the results across the board strengthen the evidence for endocrine health-related actions of EDCs. Based on this much more complete understanding of the endocrine principles by which EDCs act, including nonmonotonic dose-responses, low-dose effects, and developmental vulnerability, these findings can be much better translated to human health. Armed with this information, researchers, physicians, and other healthcare providers can guide regulators and policymakers as they make responsible decisions.
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Affiliation(s)
- A C Gore
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - V A Chappell
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - S E Fenton
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - J A Flaws
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - A Nadal
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - G S Prins
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - J Toppari
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - R T Zoeller
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
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Imran S, Ferretti P, Vrzal R. Different regulation of aryl hydrocarbon receptor-regulated genes in response to dioxin in undifferentiated and neuronally differentiated human neuroblastoma SH-SY5Y cells. Toxicol Mech Methods 2015; 25:689-97. [DOI: 10.3109/15376516.2015.1070227] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Saima Imran
- Department of Cell Biology and Genetics, Faculty of Science, Palacky University, Olomouc, Czech Republic and
| | - Patrizia Ferretti
- Stem Cells and Regenerative Medicine Section, UCL Institute of Child Health, London, UK
| | - Radim Vrzal
- Department of Cell Biology and Genetics, Faculty of Science, Palacky University, Olomouc, Czech Republic and
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21
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Larsen MC, Bushkofsky JR, Gorman T, Adhami V, Mukhtar H, Wang S, Reeder SB, Sheibani N, Jefcoate CR. Cytochrome P450 1B1: An unexpected modulator of liver fatty acid homeostasis. Arch Biochem Biophys 2015; 571:21-39. [PMID: 25703193 DOI: 10.1016/j.abb.2015.02.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 01/23/2015] [Accepted: 02/10/2015] [Indexed: 12/12/2022]
Abstract
Cytochrome P450 1b1 (Cyp1b1) expression is absent in mouse hepatocytes, but present in liver endothelia and activated stellate cells. Increased expression during adipogenesis suggests a role of Cyp1b1 metabolism in fatty acid homeostasis. Wild-type C57BL/6j (WT) and Cyp1b1-null (Cyp1b1-ko) mice were provided low or high fat diets (LFD and HFD, respectively). Cyp1b1-deletion suppressed HFD-induced obesity, improved glucose tolerance and prevented liver steatosis. Suppression of lipid droplets in sinusoidal hepatocytes, concomitant with enhanced glycogen granules, was a consistent feature of Cyp1b1-ko mice. Cyp1b1 deletion altered the in vivo expression of 560 liver genes, including suppression of PPARγ, stearoyl CoA desaturase 1 (Scd1) and many genes stimulated by PPARα, each consistent with this switch in energy storage mechanism. Ligand activation of PPARα in Cyp1b1-ko mice by WY-14643 was, nevertheless, effective. Seventeen gene changes in Cyp1b1-ko mice correspond to mouse transgenic expression that attenuated diet-induced diabetes. The absence of Cyp1b1 in mouse hepatocytes indicates participation in energy homeostasis through extra-hepatocyte signaling. Extensive sexual dimorphism in hepatic gene expression suggests a developmental impact of estrogen metabolism by Cyp1b1. Suppression of Scd1 and increased leptin turnover support enhanced leptin participation from the hypothalamus. Cyp1b1-mediated effects on vascular cells may underlie these changes.
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Affiliation(s)
- Michele Campaigne Larsen
- Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53706, United States
| | - Justin R Bushkofsky
- Molecular and Environmental Toxicology Center, University of Wisconsin, Madison, WI 53706, United States; Endocrinology and Reproductive Physiology Program, University of Wisconsin, Madison, WI 53706, United States
| | - Tyler Gorman
- Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53706, United States
| | - Vaqar Adhami
- Department of Dermatology, University of Wisconsin, Madison, WI 53706, United States
| | - Hasan Mukhtar
- Department of Dermatology, University of Wisconsin, Madison, WI 53706, United States
| | - Suqing Wang
- Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53706, United States
| | - Scott B Reeder
- Department of Radiology, University of Wisconsin, Madison, WI 53706, United States; Department of Medical Physics, University of Wisconsin, Madison, WI 53706, United States; Department of Biomedical Engineering, University of Wisconsin, Madison, WI 53706, United States; Department of Medicine, University of Wisconsin, Madison, WI 53706, United States; Department of Emergency Medicine, University of Wisconsin, Madison, WI 53706, United States
| | - Nader Sheibani
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, WI 53706, United States
| | - Colin R Jefcoate
- Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53706, United States; Molecular and Environmental Toxicology Center, University of Wisconsin, Madison, WI 53706, United States; Endocrinology and Reproductive Physiology Program, University of Wisconsin, Madison, WI 53706, United States.
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Gavin DP, Floreani C. Epigenetics of schizophrenia: an open and shut case. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 115:155-201. [PMID: 25131545 DOI: 10.1016/b978-0-12-801311-3.00005-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
During the last decade and a half, there has been an explosion of data regarding epigenetic changes in schizophrenia. Most initial studies have suggested that schizophrenia is characterized by an overly restrictive chromatin state based on increases in transcription silencing histone modifications and DNA methylation at schizophrenia candidate gene promoters and increases in the expression of enzymes that catalyze their formation. However, recent studies indicate that the pathology is more complex. This complexity may greatly impact pharmacological approaches directed at targeting epigenetic abnormalities in schizophrenia. The current review explores epigenetic studies of schizophrenia and what this can tell us about the underlying pathophysiology. We hypothesize based on recent studies that it is also plausible that drugs that further restrict chromatin may be efficacious.
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Affiliation(s)
- David P Gavin
- Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, USA; Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, USA.
| | - Christina Floreani
- Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, USA; Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, USA
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Mitchell A, Roussos P, Peter C, Tsankova N, Akbarian S. The future of neuroepigenetics in the human brain. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 128:199-228. [PMID: 25410546 DOI: 10.1016/b978-0-12-800977-2.00008-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Complex mechanisms shape the genome of brain cells into transcriptional units, clusters of condensed chromatin, and many other features that distinguish between various cell types and developmental stages sharing the same genetic material. Only a few years ago, the field's focus was almost entirely on a single mark, CpG methylation; the emerging complexity of neuronal and glial epigenomes now includes multiple types of DNA cytosine methylation, more than 100 residue-specific posttranslational histone modifications and histone variants, all of which superimposed by a dynamic and highly regulated three-dimensional organization of the chromosomal material inside the cell nucleus. Here, we provide an update on the most innovative approaches in neuroepigenetics and their potential contributions to approach cognitive functions and disorders unique to human. We propose that comprehensive, cell type-specific mappings of DNA and histone modifications, chromatin-associated RNAs, and chromosomal "loopings" and other determinants of three-dimensional genome organization will critically advance insight into the pathophysiology of the disease. For example, superimposing the epigenetic landscapes of neuronal and glial genomes onto genetic maps for complex disorders, ranging from Alzheimer's disease to schizophrenia, could provide important clues about neurological function for some of the risk-associated noncoding sequences in the human genome.
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Affiliation(s)
- Amanda Mitchell
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, USA; Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Panos Roussos
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, USA; Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, USA; Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Cyril Peter
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, USA; Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Nadejda Tsankova
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, USA; Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Schahram Akbarian
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, USA; Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, USA
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Abstract
Many cellular constituents in the human brain permanently exit from the cell cycle during pre- or early postnatal development, but little is known about epigenetic regulation of neuronal and glial epigenomes during maturation and aging, including changes in mood and psychosis spectrum disorders and other cognitive or emotional disease. Here, we summarize the current knowledge base as it pertains to genome organization in the human brain, including the regulation of DNA cytosine methylation and hydroxymethylation, and a subset of (altogether >100) residue-specific histone modifications associated with gene expression, and silencing and various other functional chromatin states. We propose that high-resolution mapping of epigenetic markings in postmortem brain tissue or neural cultures derived from induced pluripotent cells (iPS), in conjunction with transcriptome profiling and whole-genome sequencing, will increasingly be used to define the molecular pathology of specific cases diagnosed with depression, schizophrenia, autism, or other major psychiatric disease. We predict that these highly integrative explorations of genome organization and function will provide an important alternative to conventional approaches in human brain studies, which mainly are aimed at uncovering group effects by diagnosis but generally face limitations because of cohort size.
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25
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Niu Q, Liu H, Guan Z, Zeng Q, Guo S, He P, Guo L, Gao P, Xu B, Xu Z, Xia T, Wang A. The effect of c-Fos demethylation on sodium fluoride-induced apoptosis in L-02 cells. Biol Trace Elem Res 2012; 149:102-9. [PMID: 22528769 DOI: 10.1007/s12011-012-9392-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 03/09/2012] [Indexed: 10/28/2022]
Abstract
To investigate the effects of sodium fluoride (NaF) on apoptosis, c-Fos mRNA and protein expression levels, and methylation status as well as Dnmt1, Dnmt3a, and Dnmt3b mRNA expression levels in human embryo hepatocyte (L-02) which were exposed to different concentrations of NaF (0, 20, 40, and 80 mg/l) for 24 h in vitro. Results showed that the percentage of apoptosis and c-Fos mRNA and protein expression levels in 40 and 80 mg/l NaF-treated groups were higher than those in the control group (P<0.05). Further, Dnmt1 mRNA expression level was significantly decreased in the 80 mg/l NaF-treated groups compared to the control group (P<0.05); Dnmt3a and Dnmt3b mRNA expression levels were significantly decreased in 40 and 80 mg/l NaF-treated groups compared to the control group (P<0.05). c-Fos methylation levels, according to the bisulfite sequencing results, were decreased in 20, 40, and 80 mg/l NaF-treated groups against the control group. These results suggest that NaF could induce apoptosis and upregulate mRNA and protein expression level of c-Fos as well as decrease mRNA expression levels of Dnmt1, Dnmt3a, and Dnmt3b in L-02 cells. The decrease in c-Fos methylation levels might be involved in the early phase of apoptosis induced by NaF in L-02 cells.
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Affiliation(s)
- Qiang Niu
- Department of Environmental Health and MOE key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan 430030, Hubei, People's Republic of China
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26
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Singh NP, Singh UP, Singh B, Price RL, Nagarkatti M, Nagarkatti PS. Activation of aryl hydrocarbon receptor (AhR) leads to reciprocal epigenetic regulation of FoxP3 and IL-17 expression and amelioration of experimental colitis. PLoS One 2011; 6:e23522. [PMID: 21858153 PMCID: PMC3156147 DOI: 10.1371/journal.pone.0023522] [Citation(s) in RCA: 218] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 07/19/2011] [Indexed: 12/20/2022] Open
Abstract
Background Aryl hydrocarbon receptor (AhR), a transcription factor of the bHLH/PAS family, is well characterized to regulate the biochemical and toxic effects of environmental chemicals. More recently, AhR activation has been shown to regulate the differentiation of Foxp3+ Tregs as well as Th17 cells. However, the precise mechanisms are unclear. In the current study, we investigated the effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a potent AhR ligand, on epigenetic regulation leading to altered Treg/Th17 differentiation, and consequent suppression of colitis. Methodology/Principal Findings Dextran sodium sulphate (DSS) administration induced acute colitis in C57BL/6 mice, as shown by significant weight loss, shortening of colon, mucosal ulceration, and increased presence of CXCR3+ T cells as well as inflammatory cytokines. Interestingly, a single dose of TCDD (25 µg/kg body weight) was able to attenuate all of the clinical and inflammatory markers of colitis. Analysis of T cells in the lamina propria (LP) and mesenteric lymph nodes (MLN), during colitis, revealed decreased presence of Tregs and increased induction of Th17 cells, which was reversed following TCDD treatment. Activation of T cells from AhR+/+ but not AhR -/- mice, in the presence of TCDD, promoted increased differentiation of Tregs while inhibiting Th17 cells. Analysis of MLN or LP cells during colitis revealed increased methylation of CpG islands of Foxp3 and demethylation of IL-17 promoters, which was reversed following TCDD treatment. Conclusions/Significance These studies demonstrate for the first time that AhR activation promotes epigenetic regulation thereby influencing reciprocal differentiation of Tregs and Th17 cells, and amelioration of inflammation.
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MESH Headings
- Animals
- CD4-Positive T-Lymphocytes/drug effects
- CD4-Positive T-Lymphocytes/metabolism
- Cell Differentiation/drug effects
- Cells, Cultured
- Colitis/chemically induced
- Colitis/metabolism
- Colitis/prevention & control
- Colon/drug effects
- Colon/metabolism
- Colon/pathology
- CpG Islands/genetics
- Cytokines/metabolism
- DNA Methylation/drug effects
- Dextran Sulfate
- Epigenesis, Genetic
- Female
- Flow Cytometry
- Forkhead Transcription Factors/genetics
- Gene Expression Regulation
- Interleukin-17/genetics
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Polychlorinated Dibenzodioxins/pharmacology
- Receptors, Aryl Hydrocarbon/agonists
- Receptors, Aryl Hydrocarbon/genetics
- Receptors, Aryl Hydrocarbon/metabolism
- Receptors, CXCR3/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- T-Lymphocytes, Regulatory/drug effects
- T-Lymphocytes, Regulatory/metabolism
- Th17 Cells/drug effects
- Th17 Cells/metabolism
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Affiliation(s)
- Narendra P. Singh
- Department of Pathology, Microbiology and Immunology, University of South Carolina School of Medicine, Columbia, South Carolina, United States of America
| | - Udai P. Singh
- Department of Pathology, Microbiology and Immunology, University of South Carolina School of Medicine, Columbia, South Carolina, United States of America
| | - Balwan Singh
- Primate Research Center, Emory University, Atlanta, Georgia, United States of America
| | - Robert L. Price
- Department of Pathology, Microbiology and Immunology, University of South Carolina School of Medicine, Columbia, South Carolina, United States of America
| | - Mitzi Nagarkatti
- Department of Pathology, Microbiology and Immunology, University of South Carolina School of Medicine, Columbia, South Carolina, United States of America
| | - Prakash S. Nagarkatti
- Department of Pathology, Microbiology and Immunology, University of South Carolina School of Medicine, Columbia, South Carolina, United States of America
- * E-mail:
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27
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Stress-related methylation of the catechol-O-methyltransferase Val 158 allele predicts human prefrontal cognition and activity. J Neurosci 2011; 31:6692-8. [PMID: 21543598 DOI: 10.1523/jneurosci.6631-10.2011] [Citation(s) in RCA: 162] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
DNA methylation at CpG dinucleotides is associated with gene silencing, stress, and memory. The catechol-O-methyltransferase (COMT) Val(158) allele in rs4680 is associated with differential enzyme activity, stress responsivity, and prefrontal activity during working memory (WM), and it creates a CpG dinucleotide. We report that methylation of the Val(158) allele measured from peripheral blood mononuclear cells (PBMCs) of Val/Val humans is associated negatively with lifetime stress and positively with WM performance; it interacts with stress to modulate prefrontal activity during WM, such that greater stress and lower methylation are related to reduced cortical efficiency; and it is inversely related to mRNA expression and protein levels, potentially explaining the in vivo effects. Finally, methylation of COMT in prefrontal cortex and that in PBMCs of rats are correlated. The relationship of methylation of the COMT Val(158) allele with stress, gene expression, WM performance, and related brain activity suggests that stress-related methylation is associated with silencing of the gene, which partially compensates the physiological role of the high-activity Val allele in prefrontal cognition and activity. Moreover, these results demonstrate how stress-related DNA methylation of specific functional alleles impacts directly on human brain physiology beyond sequence variation.
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28
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Pozharny Y, Lambertini L, Clunie G, Ferrara L, Lee MJ. Epigenetics in women's health care. ACTA ACUST UNITED AC 2011; 77:225-35. [PMID: 20309920 DOI: 10.1002/msj.20176] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Epigenetics refers to structural modifications to genes that do not change the nucleotide sequence itself but instead control and regulate gene expression. DNA methylation, histone modification, and RNA regulation are some of the mechanisms involved in epigenetic modification. Epigenetic changes are believed to be a result of changes in an organism's environment that result in fixed and permanent changes in most differentiated cells. Some environmental changes that have been linked to epigenetic changes include starvation, folic acid, and various chemical exposures. There are periods in an organism's life cycle in which the organism is particularly susceptible to epigenetic influences; these include fertilization, gametogenesis, and early embryo development. These are also windows of opportunity for interventions during the reproductive life cycle of women to improve maternal-child health. New data suggest that epigenetic influences might be involved in the regulation of fetal development and the pathophysiology of adult diseases such as cancer, diabetes, obesity, and neurodevelopmental disorders. Various epigenetic mechanisms may also be involved in the pathogenesis of preeclampsia and intrauterine growth restriction. Additionally, environmental exposures are being held responsible for causing epigenetic changes that lead to a disease process. Exposure to heavy metals, bioflavonoids, and endocrine disruptors, such as bisphenol A and phthalates, has been shown to affect the epigenetic memory of an organism. Their long-term effects are unclear at this point, but many ongoing studies are attempting to elucidate the pathophysiological effects of such gene-environment interactions.
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29
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30
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La Merrill M, Harper R, Birnbaum LS, Cardiff RD, Threadgill DW. Maternal dioxin exposure combined with a diet high in fat increases mammary cancer incidence in mice. ENVIRONMENTAL HEALTH PERSPECTIVES 2010; 118:596-601. [PMID: 20435547 PMCID: PMC2866672 DOI: 10.1289/ehp.0901047] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Accepted: 12/09/2009] [Indexed: 05/24/2023]
Abstract
BACKGROUND RESULTS from previous studies have suggested that breast cancer risk correlates with total lifetime exposure to estrogens and that early-life 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure or diets high in fat can also increase cancer risk. OBJECTIVES Because both TCDD and diet affect the estrogen pathway, we examined how TCDD and a high-fat diet (HFD) interact to alter breast cancer susceptibility. METHODS We exposed pregnant female FVB/NJ mice (12.5 days postcoitus) to 1 microg/kg TCDD or vehicle; at parturition, the dams were randomly assigned to a low-fat diet (LFD) or a high-fat diet (HFD). Female offspring were maintained on the same diets after weaning and were exposed to 7,12-dimethylbenz[a]anthracene on postnatal days (PNDs) 35, 49, and 63 to initiate mammary tumors. A second cohort of females was treated identically until PND35 or PND49, when mammary gland morphology was examined, or PND50, when mammary gland mRNA was analyzed. RESULTS We found that maternal TCDD exposure doubled mammary tumor incidence only in mice fed the HFD. Among HFD-fed mice, maternal TCDD exposure caused rapid mammary development with increased Cyp1b1 (cytochrome P450 1B1) expression and decreased Comt (catechol-O-methyltransferase) expression in mammary tissue. Maternal TCDD exposure also increased mammary tumor Cyp1b1 expression. CONCLUSIONS Our data suggest that the HFD increases sensitivity to maternal TCDD exposure, resulting in increased breast cancer incidence, by changing metabolism capability. These results provide a mechanism to explain epidemiological data linking early-life TCDD exposure and diets high in fat to increased risk for breast cancer in humans.
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Affiliation(s)
- Michele La Merrill
- Curriculum in Toxicology, Department of Genetics, Center for Environmental and Health Susceptibility, Lineberger Cancer Center, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
| | - Rachel Harper
- Curriculum in Toxicology, Department of Genetics, Center for Environmental and Health Susceptibility, Lineberger Cancer Center, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
| | - Linda S. Birnbaum
- Experimental Toxicology Division, U.S. Environmental Protection Agency, Office of Research and Development/National Health and Environmental Effects Research Laboratory, Research Triangle Park, North Carolina, USA
- National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA
| | - Robert D. Cardiff
- Center for Comparative Medicine, Department of Pathology and Laboratory Medicine, University of California–Davis, Davis, California, USA
| | - David W. Threadgill
- Curriculum in Toxicology, Department of Genetics, Center for Environmental and Health Susceptibility, Lineberger Cancer Center, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Genetics, North Carolina State University, Raleigh, North Carolina, USA
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Fan H, Wang L, Guo F, Wei S, Zhao R. Neonatal intramuscular injection of plasmid encoding glucagon-like peptide-1 affects anxiety behaviour and expression of the hippocampal glucocorticoid receptor in adolescent rats. J Biosci 2010; 35:63-71. [DOI: 10.1007/s12038-010-0008-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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32
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Desaulniers D, Xiao GH, Lian H, Feng YL, Zhu J, Nakai J, Bowers WJ. Effects of mixtures of polychlorinated biphenyls, methylmercury, and organochlorine pesticides on hepatic DNA methylation in prepubertal female Sprague-Dawley rats. Int J Toxicol 2010; 28:294-307. [PMID: 19636072 DOI: 10.1177/1091581809337918] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
DNA methylation is one of the epigenetic mechanisms that regulates gene expression, chromosome structure, and stability. Our objective was to determine whether the DNA methylation system could be a target following in utero and postnatal exposure to human blood contaminants. Pregnant rats were dosed daily from gestation day 1 until postnatal day 21 with 2 dose levels of either organochlorine pesticides (OCP; 0.019 or 1.9 mg/kg/day), methylmercury chloride (MeHg; 0.02 or 2 mg/kg/day), polychlorinated biphenyls (PCBs; 0.011 or 1.1 mg/kg/day), or a mixture (Mix; 0.05, or 5 mg/kg/day) including all 3 groups of chemicals. Livers from 1 female offspring per litter were collected at postnatal day 29. Hepatic analysis revealed that the mRNA abundance for DNA methyltransferase (DNMT)-1, -3a, and -3b were significantly reduced by the high dose of PCB, that the high dose of MeHg also reduced mRNA levels for DNMT-1, and -3b, but that OCP had no significant effects compared with control. The high dose of PCB and Mix reduced the abundance of the universal methyl donor S-adenosylmethionine, and Mix also reduced global genome DNA methylation (5-methyl-deoxycytidine/5-methyl-deoxycytidine + deoxycytidine). The latter is consistent with pyrosequencing methylation analysis, revealing that the high-dose groups (except OCP) generally decreased the methylation of CpG sites (position -63 to -29) in the promoter of the tumor suppressor gene p16(INK4a). Overall, these hepatic results suggest that the DNA methylation system can be affected by exposure to high doses of blood contaminants, and that OCP is the least potent chemical group from the investigated mixtures.
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Affiliation(s)
- Daniel Desaulniers
- Health Canada, Healthy Environments and Consumer Safety Branch, Environmental Health Science and Research Bureau, Hazard Identification Division, Ottawa, Ontario, Canada.
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33
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Abstract
Epigenetic regulators of gene expression including DNA cytosine methylation and posttranslational histone modifications could play a role for some of the molecular alterations associated with schizophrenia. For example, in prefrontal cortex of subjects with schizophrenia, abnormal DNA or histone methylation at sites of specific genes and promoters is associated with changes in RNA expression. These findings are of interest from a neurodevelopmental perspective because there is increasing evidence that epigenetic markings for a substantial portion of genes and loci are highly regulated during the first years of life. Furthermore, there is circumstantial evidence that a subset of antipsychotic drugs, including the atypical, Clozapine, interfere with chromatin remodeling mechanisms. Challenges for the field include (1) no clear consensus yet regarding disease-associated changes, (2) the lack of cell-specific chromatin assays which makes it difficult to ascribe epigenetic alterations to specific cell populations, and (3) lack of knowledge about the stability or turnover of epigenetic markings at specific loci in (brain) chromatin. Despite these shortcomings, the study of DNA and histone modifications in chromatin extracted from diseased and control brain tissue is likely to provide valuable insight into the genomic risk architecture of schizophrenia, particularly in the large majority of cases for which a straightforward genetic cause still remains elusive,
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Affiliation(s)
- Schahram Akbarian
- Department of Psychiatry, Brudnick Neuropsychiatric Research Institute, University of Massachusetts Medical School, Worcester, MA 01604, USA.
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Akbarian S. The molecular pathology of schizophrenia--focus on histone and DNA modifications. Brain Res Bull 2009; 83:103-7. [PMID: 19729053 DOI: 10.1016/j.brainresbull.2009.08.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Revised: 06/15/2009] [Accepted: 08/24/2009] [Indexed: 10/20/2022]
Abstract
Dysfunction of cerebral cortex and other brain regions in schizophrenia is often accompanied by dysregulated expression of numerous genes. However, the underlying genetic risk architecture remains unclear for a large majority of cases. Therefore, the study of epigenetic regulators of gene expression, including covalent modifications of DNA and nucleosome core histones, offers an attractive alternative to further explore the molecular pathology of schizophrenia beyond the level of RNA quantification. Several studies reported alterations in DNA cytosine methylation and histone methylation at specific genes and promoters in postmortem brain of subjects with schizophrenia, often in conjunction with changes in levels of the corresponding RNAs. While evidence for such "epigenetic dysregulation" is increasing, many of the reported alterations await independent replication. Interestingly, studies across the lifespan indicate that DNA and histone methylation markings are developmentally regulated in human cerebral cortex, suggesting that at least some of the epigenetic changes in the brain of adult subjects with schizophrenia reflect disordered neurodevelopment.
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Affiliation(s)
- Schahram Akbarian
- Brudnick Neuropsychiatric Research Institute, Department of Psychiatry, University of Massachusetts Medical School, 303 Belmonst Street, Worcester, MA 01604, United States.
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35
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Zanette J, Jenny MJ, Goldstone JV, Woodin BR, Watka LA, Bainy ACD, Stegeman JJ. New cytochrome P450 1B1, 1C2 and 1D1 genes in the killifish Fundulus heteroclitus: Basal expression and response of five killifish CYP1s to the AHR agonist PCB126. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2009; 93:234-43. [PMID: 19515436 PMCID: PMC2761021 DOI: 10.1016/j.aquatox.2009.05.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Revised: 04/30/2009] [Accepted: 05/10/2009] [Indexed: 05/10/2023]
Abstract
Knowledge of the complement of cytochrome P450 (CYP) genes is essential to understanding detoxification and bioactivation mechanisms for organic contaminants. We cloned three new CYP1 genes, CYP1B1, CYP1C2 and CYP1D1, from the killifish Fundulus heteroclitus, an important model in environmental toxicology. Expression of the new CYP1s along with previously known CYP1A and CYP1C1 was measured by qPCR in eight different organs. Organ distribution was similar for the two CYP1Cs, but otherwise patterns and extent of expression differed among the genes. The AHR agonist 3,3',4,4',5-pentachlorobiphenyl (PCB126) (31 pmol/g fish) induced expression of CYP1A and CYP1B1 in all organs examined, while CYP1C1 was induced in all organs except testis. The largest changes in response to PCB126 were induction of CYP1A in testis (approximately 700-fold) and induction of CYP1C1 in liver (approximately 500-fold). CYP1B1 in liver and gut, CYP1A in brain and CYP1C1 in gill also were induced strongly by PCB126 (> 100-fold). CYP1C1 expression levels were higher than CYP1C2 in almost all tissues and CYP1C2 was much less responsive to PCB126. In contrast to the other genes, CYP1D1 was not induced by PCB126 in any of the organs. The organ-specific response of CYP1s to PCB126 implies differential involvement in effects of halogenated aromatic hydrocarbons in different organs. The suite of inducible CYP1s could enhance the use of F. heteroclitus in assessing aquatic contamination by AHR agonists. Determining basal and induced levels of protein and the substrate specificity for all five CYP1s will be necessary to better understand their roles in chemical effects and physiology.
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Affiliation(s)
- Juliano Zanette
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA
- Biochemistry Department, Universidade Federal de Santa Catarina, SC, Brazil
| | - Matthew J. Jenny
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA
| | - Jared V. Goldstone
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA
| | - Bruce R. Woodin
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA
| | - Lauren A. Watka
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA
- Biology Department, University of Massachusetts, Dartmouth MA
| | - Afonso C. D. Bainy
- Biochemistry Department, Universidade Federal de Santa Catarina, SC, Brazil
| | - John J. Stegeman
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA
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36
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Germann PG, Doelemeyer A, Kohler M, Mecklenburg L, Noguchi C, Nolte T, Persohn E, Seeliger F, Wendt M, Wöhrmann T. Current Status of Automation in the Process of Visualisation and Analysis: What is important for Toxicologic Pathology? J Toxicol Pathol 2008. [DOI: 10.1293/tox.21.207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
| | | | | | | | - Chihiro Noguchi
- Drug Safety and Pharmacokinetics Laboratories, Taisho Pharmaceutical Company Ltd
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Abstract
The traditional view that gene and environment interactions control disease susceptibility can now be expanded to include epigenetic reprogramming as a key determinant of origins of human disease. Currently, epigenetics is defined as heritable changes in gene expression that do not alter DNA sequence but are mitotically and transgenerationally inheritable. Epigenetic reprogramming is the process by which an organism's genotype interacts with the environment to produce its phenotype and provides a framework for explaining individual variations and the uniqueness of cells, tissues, or organs despite identical genetic information. The main epigenetic mediators are histone modification, DNA methylation, and non-coding RNAs. They regulate crucial cellular functions such as genome stability, X-chromosome inactivation, gene imprinting, and reprogramming of non-imprinting genes, and work on developmental plasticity such that exposures to endogenous or exogenous factors during critical periods permanently alter the structure or function of specific organ systems. Developmental epigenetics is believed to establish "adaptive" phenotypes to meet the demands of the later-life environment. Resulting phenotypes that match predicted later-life demands will promote health, while a high degree of mismatch will impede adaptability to later-life challenges and elevate disease risk. The rapid introduction of synthetic chemicals, medical interventions, environmental pollutants, and lifestyle choices, may result in conflict with the programmed adaptive changes made during early development, and explain the alarming increases in some diseases. The recent identification of a significant number of epigenetically regulated genes in various model systems has prepared the field to take on the challenge of characterizing distinct epigenomes related to various diseases. Improvements in human health could then be redirected from curative care to personalized, preventive medicine based, in part, on epigenetic markings etched in the "margins" of one's genetic make-up.
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Affiliation(s)
- Wan-yee Tang
- Department of Environmental Health, College of Medicine, University of Cincinnati, Cincinnati, OH, USA
| | - Shuk-mei Ho
- Department of Environmental Health and Cancer Center, College of Medicine, University of Cincinnati, Cincinnati, OH, USA
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38
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Haining RL, Nichols-Haining M. Cytochrome P450-catalyzed pathways in human brain: Metabolism meets pharmacology or old drugs with new mechanism of action? Pharmacol Ther 2007; 113:537-45. [PMID: 17270273 DOI: 10.1016/j.pharmthera.2006.11.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Accepted: 11/21/2006] [Indexed: 02/02/2023]
Abstract
The true importance of cytochrome P450 enzymes, not just in drug metabolism but also in pharmacology, is only beginning to be appreciated. Though originally discovered through their role in the biotransformation of xenobiotics, the P450 enzyme super family is ubiquitous in nature and necessarily evolved around endogenous pathways. The extent of tissue- and cell-specific expression of individual P450 isoforms has led many investigators to hypothesize localized roles in endogenous biochemical pathways for isoforms traditionally thought of as drug-metabolizing. In some cases, direct evidence from humanized transgenic animal models can confirm the degree to which such enzymes modulate endogenous pathways. However, overlapping P450 substrate specificities may mask genetic or biochemical deficiencies, such that many of these reactions appear nonessential. Nonetheless, the drug-induced alteration of local biochemical concentrations in extrahepatic tissues due to metabolism by and inhibition of P450 isoforms has tremendous potential for introducing unexpected pharmacological effects. Nowhere is this truer than in the CNS. On the other hand, if we can harness the power of in silico modeling to create highly specific inhibitors of identified brain isoforms, a novel avenue for drug design using P450 as drug targets may be at hand. This article highlights some notable examples in which the catalytic state of specific P450 isoforms involved in endogenous biochemical reaction pathways are influenced by pharmacological agents. The implications of inhibition of P450-catalzyed oxidation steps that are known or speculated to influence arachadonic acid, cholesterol, and catecholamine neurotransmitters pathways in human brain will be considered.
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Affiliation(s)
- Robert L Haining
- West Virginia University, Department of Basic Pharmaceutical Sciences, Morgantown, WV 26505, United States.
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39
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Eichenlaub-Ritter U, Winterscheidt U, Vogt E, Shen Y, Tinneberg HR, Sorensen R. 2-methoxyestradiol induces spindle aberrations, chromosome congression failure, and nondisjunction in mouse oocytes. Biol Reprod 2007; 76:784-93. [PMID: 17229934 DOI: 10.1095/biolreprod.106.055111] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
2-Methoxyestradiol (2-ME) is a metabolite of 17beta-estradiol and a natural component of follicular fluid. Local concentrations of 2-ME may be increased by exposure to environmental pollutants that activate the expression of enzymes in the metabolic pathway from 17beta-estradiol to 2-ME. It has been suspected that this may have adverse effects on spindle formation in maturing oocytes, which would affect embryo quality. To study the dose-response patterns, we exposed denuded mouse oocytes to 2-ME during in vitro maturation. Meiotic progression, spindle morphology, centrosome integrity, and chromosome congression were examined by immunofluorescence and noninvasive polarizing microscopy (PolScope). Chromosomal constituents were assessed after spreading and C-banding. 2-ME sustained MAD2L1 expression at the centromeres and increased the number of meiosis I-blocked oocytes in a dose-dependent manner. 2-ME also caused dramatic dose-dependent increases in the hyperploidy of metaphase II oocytes. Some of these meiosis II oocytes contained anaphase I-like chromosomes, which suggests that high concentrations of the catecholestradiol interfere with the physical separation of chromosomes. Noninvasive PolScope analysis and tubulin immunofluorescence revealed that perturbations in spindle organization, which resulted in severe disturbances of the chromosome alignment at the spindle equator (congression failure), were caused by 2-ME at meiosis I and II. Pericentrin-positive centrosomes failed to align at the spindle poles, and multipolar spindles and prominent arrays of cytoplasmic microtubule asters were induced in 2-ME-exposed metaphase II oocytes. In conclusion, a micromolar level of 2-ME is aneugenic for mammalian oocytes. Therefore, exposure to 2-ME and conditions that increase the intrinsic local concentration of 2-ME in the ovary may affect fertility and increase risks for chromosomal aberrations in the oocyte and embryo.
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Affiliation(s)
- Ursula Eichenlaub-Ritter
- University of Bielefeld, Faculty of Biology, Institute of Gene Technology/Microbiology, D-33501 Bielefeld, Germany.
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