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Šimečková P, Pěnčíková K, Kováč O, Slavík J, Pařenicová M, Vondráček J, Machala M. In vitro profiling of toxic effects of environmental polycyclic aromatic hydrocarbons on nuclear receptor signaling, disruption of endogenous metabolism and induction of cellular stress. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 815:151967. [PMID: 34843781 DOI: 10.1016/j.scitotenv.2021.151967] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 11/03/2021] [Accepted: 11/22/2021] [Indexed: 06/13/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) may interact with multiple intracellular receptors and related signaling pathways. We comprehensively evaluated the toxicity profiles of six environmentally relevant PAHs differing in structure, genotoxicity and their ability to activate the aryl hydrocarbon receptor (AhR). We focused particularly on their impact on intracellular hormone-, xenobiotic- and lipid-sensing receptors, as well as on cellular stress markers, combining a battery of human reporter gene assays and qRT-PCR evaluation of endogenous gene expression in human hepatocyte-like HepaRG cells, with LC/MS-MS analysis of cellular sphingolipids. The effects of PAHs included: activation of estrogen receptor α (in case of fluoranthene (Fla), pyrene (Pyr), benz[a]anthracene (BaA), benzo[a]pyrene (BaP)), suppression of androgen receptor activity (Fla, BaA, BaP and benzo[k]fluoranthene (BkF)), enhancement of dexamethasone-induced glucocorticoid receptor activity (chrysene (Chry), BaA, and BaP), and potentiation of triiodothyronine-induced thyroid receptor α activity (all tested PAHs). PAHs also induced transcription of endogenous gene targets of constitutive androstane receptor (Fla, Pyr), or repression of target genes of pregnane X receptor and peroxisome proliferator-activated receptor α (in case of the AhR-activating PAHs - Chry, BaA, BaP, and BkF) in HepaRG cells. In the same cell model, the AhR agonists reduced the expression of glucose metabolism genes (PCK1, G6PC and PDK4), and they up-regulated levels of glucosylceramides, together with a concomitant induction of expression of UGCG, glucosylceramide synthesis enzyme. Finally, both BaP and BkF were found to induce expression of early stress and genotoxicity markers: ATF3, EGR1, GDF15, CDKN1A/p21, and GADD45A mRNAs, while BaP alone increased levels of IL-6 mRNA. Overall, whereas low-molecular-weight PAHs exerted significant effects on nuclear receptors (with CYP2B6 induction observed already at nanomolar concentrations), the AhR activation by 4-ring and 5-ring PAHs appeared to be a key mechanism underlying their impact on nuclear receptor signaling, endogenous metabolism and induction of early stress and genotoxicity markers.
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Affiliation(s)
- Pavlína Šimečková
- Department of Pharmacology and Toxicology, Veterinary Research Institute, 62100 Brno, Czech Republic
| | - Kateřina Pěnčíková
- Department of Pharmacology and Toxicology, Veterinary Research Institute, 62100 Brno, Czech Republic
| | - Ondrej Kováč
- Department of Pharmacology and Toxicology, Veterinary Research Institute, 62100 Brno, Czech Republic
| | - Josef Slavík
- Department of Pharmacology and Toxicology, Veterinary Research Institute, 62100 Brno, Czech Republic
| | - Martina Pařenicová
- Department of Pharmacology and Toxicology, Veterinary Research Institute, 62100 Brno, Czech Republic
| | - Jan Vondráček
- Department of Cytokinetics, Institute of Biophysics of the Czech Academy of Sciences, 61265 Brno, Czech Republic
| | - Miroslav Machala
- Department of Pharmacology and Toxicology, Veterinary Research Institute, 62100 Brno, Czech Republic.
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Eti NA, Flor S, Iqbal K, Scott RL, Klenov VE, Gibson-Corley KN, Soares MJ, Ludewig G, Robertson LW. PCB126 induced toxic actions on liver energy metabolism is mediated by AhR in rats. Toxicology 2022; 466:153054. [PMID: 34848246 PMCID: PMC8748418 DOI: 10.1016/j.tox.2021.153054] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 11/18/2021] [Accepted: 11/25/2021] [Indexed: 02/01/2023]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor involved in the regulation of biological responses to more planar aromatic hydrocarbons, like TCDD. We previously described the sequence of events following exposure of male rats to a dioxin-like polychlorinated biphenyl (PCB) congener, 3,3',4,4',5-pentachlorobiphenyl (PCB126), that binds avidly to the AhR and causes various types of toxicity including metabolic syndrome, fatty liver, and disruption of energy homeostasis. The purpose of this study was, to investigate the role of AhR to mediate those toxic manifestations following sub-acute exposure to PCB126 and to examine possible sex differences in effects. For this goal, we created an AhR knockout (AhR-KO) model using CRISPR/Cas9. Comparison was made to the wild type (WT) male and female Holtzman Sprague Dawley rats. Rats were injected with a single IP dose of corn oil vehicle or 5 μmol/kg PCB126 in corn oil and necropsied after 28 days. PCB126 caused significant weight loss, reduced relative thymus weights, and increased relative liver weights in WT male and female rats, but not in AhR-KO rats. Similarly, significant pathologic changes were visible which included necrosis and regeneration in female rats, micro- and macro-vesicular hepatocellular vacuolation in males, and a paucity of glycogen in livers of both sexes in WT rats only. Hypoglycemia and lower IGF1, and reduced serum non-esterified fatty acids (NEFAs) were found in serum of both sexes of WT rats, low serum cholesterol levels only in the females, and no changes in AhR-KO rats. The expression of genes encoding enzymes related to xenobiotic metabolism (e.g. CYP1A1), gluconeogenesis, glycogenolysis, and fatty acid oxidation were unaffected in the AhR-KO rats following PCB126 exposure as opposed to WT rats where expression was significantly upregulated (PPARα, females only) or downregulated suggesting a disrupted energy homeostasis. Interestingly, Acox2, Hmgcs, G6Pase and Pc were affected in both sexes, the gluconeogenesis and glucose transporter genes Pck1, Glut2, Sds, and Crem only in male WT-PCB rats. These results show the essential role of the AhR in glycogenolysis, gluconeogenesis, and fatty acid oxidation, i.e. in the regulation of energy production and homeostasis, but also demonstrate a significant difference in the effects of PCB126 in males verses females, suggesting higher vulnerability of glucose homeostasis in males and more changes in fatty acid/lipid homeostasis in females. These differences in effects, which may apply to more/all AhR agonists, should be further analyzed to identify health risks to specific groups of highly exposed human populations.
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Affiliation(s)
- Nazmin Akter Eti
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, IA, United States
| | - Susanne Flor
- Department of Radiation Oncology, University of Iowa, Iowa City, IA, United States
| | - Khursheed Iqbal
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS, United States
| | - Regan L Scott
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS, United States
| | - Violet E Klenov
- Department of Ob/Gyn, University of Iowa, Iowa City, IA, United States
| | - Katherine N Gibson-Corley
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, United States
| | - Michael J Soares
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS, United States
| | - Gabriele Ludewig
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, IA, United States
| | - Larry W Robertson
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, IA, United States.
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Bock KW. Aryl hydrocarbon receptor (AHR) functions in infectious and sterile inflammation and NAD +-dependent metabolic adaptation. Arch Toxicol 2021; 95:3449-3458. [PMID: 34559251 PMCID: PMC8461142 DOI: 10.1007/s00204-021-03134-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 08/11/2021] [Indexed: 01/13/2023]
Abstract
Aryl hydrocarbon receptor (AHR) research has shifted from exploring dioxin toxicity to elucidation of various physiologic AHR functions. Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is known to exert cellular stress-mediated sterile inflammatory responses in exposed human tissues but may be lethal in sensitive species. Inflammation can be thought of as the extreme end of a spectrum ranging from homeostasis to stress responses (sterile inflammation) and to defense against infection (infectious inflammation). Defense against bacterial infection by generation of reactive oxygen species has to be strictly controlled and may use up a considerable amount of energy. NAD+-mediated energy metabolism adapts to various inflammatory responses. As examples, the present commentary tries to integrate responses of AHR and NAD+-consuming enzymes (PARP7/TiPARP, CD38 and sirtuins) into infectious and stress-induced inflammatory responses, the latter exemplified by nonalcoholic fatty liver disease (NAFLD). TCDD toxicity models in sensitive species provide hints to molecular AHR targets of energy metabolism including gluconeogenesis and glycolysis. AHR research remains challenging and promising.
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Affiliation(s)
- Karl Walter Bock
- Institute of Experimental and Clinical Pharmacology and Toxicology, Wilhelmstrasse 56, 72074, Tübingen, Germany.
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PARPs in lipid metabolism and related diseases. Prog Lipid Res 2021; 84:101117. [PMID: 34450194 DOI: 10.1016/j.plipres.2021.101117] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 08/10/2021] [Accepted: 08/18/2021] [Indexed: 12/28/2022]
Abstract
PARPs and tankyrases (TNKS) represent a family of 17 proteins. PARPs and tankyrases were originally identified as DNA repair factors, nevertheless, recent advances have shed light on their role in lipid metabolism. To date, PARP1, PARP2, PARP3, tankyrases, PARP9, PARP10, PARP14 were reported to have multi-pronged connections to lipid metabolism. The activity of PARP enzymes is fine-tuned by a set of cholesterol-based compounds as oxidized cholesterol derivatives, steroid hormones or bile acids. In turn, PARPs modulate several key processes of lipid homeostasis (lipotoxicity, fatty acid and steroid biosynthesis, lipoprotein homeostasis, fatty acid oxidation, etc.). PARPs are also cofactors of lipid-responsive nuclear receptors and transcription factors through which PARPs regulate lipid metabolism and lipid homeostasis. PARP activation often represents a disruptive signal to (lipid) metabolism, and PARP-dependent changes to lipid metabolism have pathophysiological role in the development of hyperlipidemia, obesity, alcoholic and non-alcoholic fatty liver disease, type II diabetes and its complications, atherosclerosis, cardiovascular aging and skin pathologies, just to name a few. In this synopsis we will review the evidence supporting the beneficial effects of pharmacological PARP inhibitors in these diseases/pathologies and propose repurposing PARP inhibitors already available for the treatment of various malignancies.
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Roles of the ubiquitin ligase CUL4B and ADP-ribosyltransferase TiPARP in TCDD-induced nuclear export and proteasomal degradation of the transcription factor AHR. J Biol Chem 2021; 297:100886. [PMID: 34146543 PMCID: PMC8318916 DOI: 10.1016/j.jbc.2021.100886] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/08/2021] [Accepted: 06/15/2021] [Indexed: 12/14/2022] Open
Abstract
The aryl hydrocarbon receptor (AHR) is a transcription factor activated by exogenous halogenated polycyclic aromatic hydrocarbon compounds, including the environmental toxin TCDD, 2,3,7,8-tetrachlorodibenzo-p-dioxin, and naturally occurring dietary and endogenous compounds. The activated AHR enhances transcription of specific genes including phase I and phase II metabolism enzymes and other targets genes such as the TCDD-inducible poly(ADP-ribose) polymerase (TiPARP). The regulation of AHR activation is a dynamic process: immediately after transcriptional activation of the AHR by TCDD, the AHR is exported from the nucleus to the cytoplasm where it is subjected to proteasomal degradation. However, the mechanisms regulating AHR degradation are not well understood. Here, we studied the role of two enzymes reported to enhance AHR breakdown: the cullin 4B (CUL4B)AHR complex, an E3 ubiquitin ligase that targets the AHR and other proteins for ubiquitination, and TiPARP, which targets proteins for ADP-ribosylation, a posttranslational modification that can increase susceptibility to degradation. Using a WT mouse embryonic fibroblast (MEF) cell line and an MEF cell line in which CUL4B has been deleted (MEFCul4b-null), we discovered that loss of CUL4B partially prevented AHR degradation after TCDD exposure, while knocking down TiPARP in MEFCul4b-null cells completely abolished AHR degradation upon TCDD treatment. Increased TCDD-activated AHR protein levels in MEFCul4b-null and MEFCul4b-null cells in which TiPARP was knocked down led to enhanced AHR transcriptional activity, indicating that CUL4B and TiPARP restrain AHR action. This study reveals a novel function of TiPARP in controlling TCDD-activated AHR nuclear export and subsequent proteasomal degradation.
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First evidence of aryl hydrocarbon receptor as a druggable target in hypertension induced by chronic intermittent hypoxia. Pharmacol Res 2020; 159:104869. [DOI: 10.1016/j.phrs.2020.104869] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/15/2020] [Accepted: 04/24/2020] [Indexed: 02/08/2023]
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Liu X, Wang X, Liu J, Wang X, Bao H. Identifying Candidate Genes for Hypoxia Adaptation of Tibet Chicken Embryos by Selection Signature Analyses and RNA Sequencing. Genes (Basel) 2020; 11:E823. [PMID: 32698384 PMCID: PMC7397227 DOI: 10.3390/genes11070823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/15/2020] [Accepted: 07/17/2020] [Indexed: 11/16/2022] Open
Abstract
The Tibet chicken (Gallus gallus) lives on the Qinghai-Tibet Plateau and adapts to the hypoxic environment very well. The objectives of this study was to obtain candidate genes associated with hypoxia adaptation in the Tibet chicken embryos. In the present study, we used the fixation index (Fst) and cross population extended haplotype homozygosity (XPEHH) statistical methods to detect signatures of positive selection of the Tibet chicken, and analyzed the RNA sequencing data from the embryonic liver and heart with HISAT, StringTie and Ballgown for differentially expressed genes between the Tibet chicken and White leghorn (Gallus gallus, a kind of lowland chicken) embryos hatched under hypoxia condition. Genes which were screened out by both selection signature analysis and RNA sequencing analysis could be regarded as candidate genes for hypoxia adaptation of chicken embryos. We screened out 1772 genes by XPEHH and 601 genes by Fst, and obtained 384 and 353 differentially expressed genes in embryonic liver and heart, respectively. Among these genes, 89 genes were considered as candidate genes for hypoxia adaptation in chicken embryos. ARNT, AHR, GSTK1 and FGFR1 could be considered the most important candidate genes. Our findings provide references to elucidate the molecular mechanism of hypoxia adaptation in Tibet chicken embryos.
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Affiliation(s)
- Xiayi Liu
- National Engineering Laboratory for Animal Breeding, Beijing Key Laboratory of Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; (X.L.); (J.L.)
| | - Xiaochen Wang
- Chinese Academy of Sciences Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Beijing 100101, China;
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jing Liu
- National Engineering Laboratory for Animal Breeding, Beijing Key Laboratory of Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; (X.L.); (J.L.)
| | - Xiangyu Wang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Haigang Bao
- National Engineering Laboratory for Animal Breeding, Beijing Key Laboratory of Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; (X.L.); (J.L.)
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Does NLRP3 Inflammasome and Aryl Hydrocarbon Receptor Play an Interlinked Role in Bowel Inflammation and Colitis-Associated Colorectal Cancer? Molecules 2020; 25:molecules25102427. [PMID: 32456012 PMCID: PMC7287590 DOI: 10.3390/molecules25102427] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/17/2020] [Accepted: 05/21/2020] [Indexed: 12/22/2022] Open
Abstract
Inflammation is a hallmark in many forms of cancer; with colitis-associated colorectal cancer (CAC) being a progressive intestinal inflammation due to inflammatory bowel disease (IBD). While this is an exemplification of the negatives of inflammation, it is just as crucial to have some degree of the inflammatory process to maintain a healthy immune system. A pivotal component in the maintenance of such intestinal homeostasis is the innate immunity component, inflammasomes. Inflammasomes are large, cytosolic protein complexes formed following stimulation of microbial and stress signals that lead to the expression of pro-inflammatory cytokines. The NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome has been extensively studied in part due to its strong association with colitis and CAC. The aryl hydrocarbon receptor (AhR) has recently been acknowledged for its connection to the immune system aside from its role as an environmental sensor. AhR has been described to play a role in the inhibition of the NLRP3 inflammasome activation pathway. This review will summarise the signalling pathways of both the NLRP3 inflammasome and AhR; as well as new-found links between these two signalling pathways in intestinal immunity and some potential therapeutic agents that have been found to take advantage of this link in the treatment of colitis and CAC.
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Wigle TJ, Church WD, Majer CR, Swinger KK, Aybar D, Schenkel LB, Vasbinder MM, Brendes A, Beck C, Prahm M, Wegener D, Chang P, Kuntz KW. Forced Self-Modification Assays as a Strategy to Screen MonoPARP Enzymes. SLAS DISCOVERY 2019; 25:241-252. [PMID: 31855104 PMCID: PMC7036481 DOI: 10.1177/2472555219883623] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Mono(ADP-ribosylation) (MARylation) and poly(ADP-ribosylation) (PARylation) are
posttranslational modifications found on multiple amino acids. There are 12
enzymatically active mono(ADP-ribose) polymerase (monoPARP) enzymes and 4
enzymatically active poly(ADP-ribose) polymerase (polyPARP) enzymes that use
nicotinamide adenine dinucleotide (NAD+) as the ADP-ribose donating
substrate to generate these modifications. While there are approved drugs and
clinical trials ongoing for the enzymes that perform PARylation, MARylation is
gaining recognition for its role in immune function, inflammation, and cancer.
However, there is a lack of chemical probes to study the function of monoPARPs
in cells and in vivo. An important first step to generating chemical probes for
monoPARPs is to develop biochemical assays to enable hit finding, and
determination of the potency and selectivity of inhibitors. Complicating the
development of enzymatic assays is that it is poorly understood how monoPARPs
engage their substrates. To overcome this, we have developed a family-wide
approach to developing robust high-throughput monoPARP assays where the enzymes
are immobilized and forced to self-modify using biotinylated-NAD+,
which is detected using a dissociation-enhanced lanthanide fluorescence
immunoassay (DELFIA) readout. Herein we describe the development of assays for
12 monoPARPs and 3 polyPARPs and apply them to understand the potency and
selectivity of a focused library of inhibitors across this family.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Paul Chang
- Ribon Therapeutics Inc., Cambridge, MA, USA
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Leblanc AF, Attignon EA, Distel E, Karakitsios SP, Sarigiannis DA, Bortoli S, Barouki R, Coumoul X, Aggerbeck M, Blanc EB. A dual mixture of persistent organic pollutants modifies carbohydrate metabolism in the human hepatic cell line HepaRG. ENVIRONMENTAL RESEARCH 2019; 178:108628. [PMID: 31520823 DOI: 10.1016/j.envres.2019.108628] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 07/12/2019] [Accepted: 08/04/2019] [Indexed: 06/10/2023]
Abstract
Individuals as well as entire ecosystems are exposed to mixtures of Persistent Organic Pollutants (POPs). Previously, we showed, by a non-targeted approach, that the expression of several genes involved in carbohydrate metabolism was almost completely inhibited in the human hepatic cell line HepaRG following exposure to a mixture of the organochlorine insecticide alpha-endosulfan and 2,3,7,8 tetrachlorodibenzo-p-dioxin. In this European HEALS project, which studies the effects of the exposome on human health, we used a Physiologically Based BioKinetic model to compare the concentrations previously used in vitro with in vivo exposures for humans. We investigated the effects of these POPs on the levels of proteins, on glycogen content, glucose production and the oxidation of glucose into CO2 and correlated them to the expression of genes involved in carbohydrate metabolism as measured by RT-qPCR. Exposure to individual POPs and the mixture decreased the expression of the proteins investigated as well as glucose output (up to 82%), glucose oxidation (up to 29%) and glycogen content (up to 48%). siRNAs that specifically inhibit the expression of several xenobiotic receptors were used to assess receptor involvement in the effects of the POPs. In the HepaRG model, we demonstrate that the effects are mediated by the aryl hydrocarbon receptor and the estrogen receptor alpha, but not the pregnane X receptor or the constitutive androstane receptor. These results provide evidence that exposure to combinations of POPs, acting through different signaling pathways, may affect, more profoundly than single pollutants alone, metabolic pathways such as carbohydrate/energy metabolism and play a potential role in pollutant associated metabolic disorders.
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Affiliation(s)
- Alix F Leblanc
- INSERM UMR-S 1124, Toxicité Environnementale, Cibles Thérapeutiques, Signalisation Cellulaire et Biomarqueurs, 45 rue des Saints Pères, 75006, Paris, France; Université de Paris, Université Paris Descartes, 45 rue des Saints Pères, 75006, Paris, France.
| | - Eléonore A Attignon
- INSERM UMR-S 1124, Toxicité Environnementale, Cibles Thérapeutiques, Signalisation Cellulaire et Biomarqueurs, 45 rue des Saints Pères, 75006, Paris, France; Université de Paris, Université Paris Descartes, 45 rue des Saints Pères, 75006, Paris, France.
| | - Emilie Distel
- INSERM UMR-S 1124, Toxicité Environnementale, Cibles Thérapeutiques, Signalisation Cellulaire et Biomarqueurs, 45 rue des Saints Pères, 75006, Paris, France; Université de Paris, Université Paris Descartes, 45 rue des Saints Pères, 75006, Paris, France.
| | - Spyros P Karakitsios
- Aristotle University of Thessaloniki, Department of Chemical Engineering, 54 124, Thessaloniki, Greece.
| | - Dimosthenis A Sarigiannis
- Aristotle University of Thessaloniki, Department of Chemical Engineering, 54 124, Thessaloniki, Greece; Environmental Health Engineering, Institute for Advanced Study, Pavia, Italy.
| | - Sylvie Bortoli
- INSERM UMR-S 1124, Toxicité Environnementale, Cibles Thérapeutiques, Signalisation Cellulaire et Biomarqueurs, 45 rue des Saints Pères, 75006, Paris, France; Université de Paris, Université Paris Descartes, 45 rue des Saints Pères, 75006, Paris, France.
| | - Robert Barouki
- INSERM UMR-S 1124, Toxicité Environnementale, Cibles Thérapeutiques, Signalisation Cellulaire et Biomarqueurs, 45 rue des Saints Pères, 75006, Paris, France; Université de Paris, Université Paris Descartes, 45 rue des Saints Pères, 75006, Paris, France; AP-HP, Hôpital Necker-Enfants Malades, Service de Biochimie Métabolique, 149, rue de Sèvres, 75743, Paris, France.
| | - Xavier Coumoul
- INSERM UMR-S 1124, Toxicité Environnementale, Cibles Thérapeutiques, Signalisation Cellulaire et Biomarqueurs, 45 rue des Saints Pères, 75006, Paris, France; Université de Paris, Université Paris Descartes, 45 rue des Saints Pères, 75006, Paris, France.
| | - Martine Aggerbeck
- INSERM UMR-S 1124, Toxicité Environnementale, Cibles Thérapeutiques, Signalisation Cellulaire et Biomarqueurs, 45 rue des Saints Pères, 75006, Paris, France; Université de Paris, Université Paris Descartes, 45 rue des Saints Pères, 75006, Paris, France.
| | - Etienne B Blanc
- INSERM UMR-S 1124, Toxicité Environnementale, Cibles Thérapeutiques, Signalisation Cellulaire et Biomarqueurs, 45 rue des Saints Pères, 75006, Paris, France; Université de Paris, Université Paris Descartes, 45 rue des Saints Pères, 75006, Paris, France.
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Functions of aryl hydrocarbon receptor (AHR) and CD38 in NAD metabolism and nonalcoholic steatohepatitis (NASH). Biochem Pharmacol 2019; 169:113620. [PMID: 31465774 DOI: 10.1016/j.bcp.2019.08.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 08/22/2019] [Indexed: 12/20/2022]
Abstract
Aryl hydrocarbon receptor (AHR), identified in studies of dioxin toxicity, has been characterized as ligand-activated transcription factor involved in diverse functions including microbial defense, cell proliferation, immunity and NAD metabolism. AHR targets of the latter function are PARPs/ARTs and CD38 that are regulating glucose and lipid metabolism via NAD-dependent sirtuins. Deregulation of these pathways may facilitate obesity and age-dependent pathologies. The present commentary is focused on AHR and CD38 signaling in liver. CD38 is functioning as ectoNADase and Ca2+ mobilizing enzyme in endoplasmic reticulum and endolysosomal membranes. Deregulation of TCDD-activated AHR and CD38 may facilitate hepatic steatosis and inflammation. However, these proteins are also involved in protection against inflammation and CD38-mediated age-related decreased NAD levels that may be responsible for neurodegeneration. Further knowledge about the complexity of these pathways is needed to avoid pathologies. Therapeutic modulation of AHR and CD38 remains a challenging task.
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Bock KW. Aryl hydrocarbon receptor (AHR) functions in NAD + metabolism, myelopoiesis and obesity. Biochem Pharmacol 2019; 163:128-132. [PMID: 30779909 DOI: 10.1016/j.bcp.2019.02.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 02/15/2019] [Indexed: 12/27/2022]
Abstract
Diverse physiologic functions of AHR, a transcription factor discovered in studies of dioxin toxicity, are currently elucidated in many laboratories including chemical and microbial defense, immunity and myelopoiesis. Accumulating evidence suggests that AHR may also be involved in obesity and TCDD-mediated lethality in sensitive species. Underlying mechanisms include NAD+- and sirtuin-mediated deregulation of lipid, glucose and NAD+ homeostasis. Progress in NAD metabolome research suggests large consumption of NAD+ by NAD glycohydrolases (NADases) and NAD-dependent sirtuins. In focus are two NADases: (i) TiPARP (TCDD-induced poly(ADP-ribose) polymerase), one of several nuclear NADases, and (ii) plasma membrane-bound ectoNADase/CD38, a multifunctional enzyme and receptor. CD38 is involved in extra- and intracellular NAD degradation but acts also as differentiation marker. Both CD38 and AHR are components of a complex signalsome that enhances retinoic acid-induced differentiation of myeloid progenitor cells to granulocytes. Further advances of NAD metabolome research may lead to therapeutic options in the control of obesity and to improved risk assessment of TCDD toxicity.
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Affiliation(s)
- Karl Walter Bock
- Department of Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Wilhelmstrasse 56, D-72074 Tübingen, Germany.
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Corre S, Tardif N, Mouchet N, Leclair HM, Boussemart L, Gautron A, Bachelot L, Perrot A, Soshilov A, Rogiers A, Rambow F, Dumontet E, Tarte K, Bessede A, Guillemin GJ, Marine JC, Denison MS, Gilot D, Galibert MD. Sustained activation of the Aryl hydrocarbon Receptor transcription factor promotes resistance to BRAF-inhibitors in melanoma. Nat Commun 2018; 9:4775. [PMID: 30429474 PMCID: PMC6235830 DOI: 10.1038/s41467-018-06951-2] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 09/12/2018] [Indexed: 12/20/2022] Open
Abstract
BRAF inhibitors target the BRAF-V600E/K mutated kinase, the driver mutation found in 50% of cutaneous melanoma. They give unprecedented anti-tumor responses but acquisition of resistance ultimately limits their clinical benefit. The master regulators driving the expression of resistance-genes remain poorly understood. Here, we demonstrate that the Aryl hydrocarbon Receptor (AhR) transcription factor is constitutively activated in a subset of melanoma cells, promoting the dedifferentiation of melanoma cells and the expression of BRAFi-resistance genes. Typically, under BRAFi pressure, death of BRAFi-sensitive cells leads to an enrichment of a small subpopulation of AhR-activated and BRAFi-persister cells, responsible for relapse. Also, differentiated and BRAFi-sensitive cells can be redirected towards an AhR-dependent resistant program using AhR agonists. We thus identify Resveratrol, a clinically compatible AhR-antagonist that abrogates deleterious AhR sustained-activation. Combined with BRAFi, Resveratrol reduces the number of BRAFi-resistant cells and delays tumor growth. We thus propose AhR-impairment as a strategy to overcome melanoma resistance.
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Affiliation(s)
- Sébastien Corre
- IGDR (Institut de Génétique et Développement de Rennes)-UMR6290, CNRS, Univ Rennes, F-35000, Rennes, France.
| | - Nina Tardif
- IGDR (Institut de Génétique et Développement de Rennes)-UMR6290, CNRS, Univ Rennes, F-35000, Rennes, France
| | - Nicolas Mouchet
- IGDR (Institut de Génétique et Développement de Rennes)-UMR6290, CNRS, Univ Rennes, F-35000, Rennes, France
| | - Héloïse M Leclair
- IGDR (Institut de Génétique et Développement de Rennes)-UMR6290, CNRS, Univ Rennes, F-35000, Rennes, France
| | - Lise Boussemart
- IGDR (Institut de Génétique et Développement de Rennes)-UMR6290, CNRS, Univ Rennes, F-35000, Rennes, France.,Department of Dermatology, Hospital University of Rennes (CHU Rennes), F-35000, Rennes, France
| | - Arthur Gautron
- IGDR (Institut de Génétique et Développement de Rennes)-UMR6290, CNRS, Univ Rennes, F-35000, Rennes, France
| | - Laura Bachelot
- IGDR (Institut de Génétique et Développement de Rennes)-UMR6290, CNRS, Univ Rennes, F-35000, Rennes, France
| | - Anthony Perrot
- IGDR (Institut de Génétique et Développement de Rennes)-UMR6290, CNRS, Univ Rennes, F-35000, Rennes, France
| | - Anatoly Soshilov
- Department of Environmental Toxicology, University of California, Meyer Hall, Davis, CA, 95616, USA
| | - Aljosja Rogiers
- Laboratory for Molecular Cancer Biology, VIB Center for Cancer Biology, VIB, Leuven, 3000, Belgium.,Laboratory for Molecular Cancer Biology, Department of Oncology, KU Leuven, Leuven, 3000, Belgium
| | - Florian Rambow
- Laboratory for Molecular Cancer Biology, VIB Center for Cancer Biology, VIB, Leuven, 3000, Belgium.,Laboratory for Molecular Cancer Biology, Department of Oncology, KU Leuven, Leuven, 3000, Belgium
| | - Erwan Dumontet
- MICMAC (MIcroenvironment, Cell differentiation, iMmunology And Cancer)-UMR_S 1236, Inserm, Univ Rennes, F-35000, Rennes, France
| | - Karin Tarte
- MICMAC (MIcroenvironment, Cell differentiation, iMmunology And Cancer)-UMR_S 1236, Inserm, Univ Rennes, F-35000, Rennes, France
| | | | - Gilles J Guillemin
- Neuroinflammation Group, MND and Neurodegenerative Diseases Research Center, Macquarie University, Sydney, NSW, 2109, Australia
| | - Jean-Christophe Marine
- Laboratory for Molecular Cancer Biology, VIB Center for Cancer Biology, VIB, Leuven, 3000, Belgium.,Laboratory for Molecular Cancer Biology, Department of Oncology, KU Leuven, Leuven, 3000, Belgium
| | - Michael S Denison
- Department of Environmental Toxicology, University of California, Meyer Hall, Davis, CA, 95616, USA
| | - David Gilot
- IGDR (Institut de Génétique et Développement de Rennes)-UMR6290, CNRS, Univ Rennes, F-35000, Rennes, France.
| | - Marie-Dominique Galibert
- IGDR (Institut de Génétique et Développement de Rennes)-UMR6290, CNRS, Univ Rennes, F-35000, Rennes, France. .,Department of Molecular Genetics and Genomics, Hospital University of Rennes (CHU Rennes), F-35000, Rennes, France.
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Abstract
Poly(ADP-ribose) polymerase (PARP)10 is a PARP family member that performs mono-ADP-ribosylation of target proteins. Recent studies have linked PARP10 to metabolic processes and metabolic regulators that prompted us to assess whether PARP10 influences mitochondrial oxidative metabolism. The depletion of PARP10 by specific shRNAs increased mitochondrial oxidative capacity in cellular models of breast, cervical, colorectal and exocrine pancreas cancer. Upon silencing of PARP10, mitochondrial superoxide production decreased in line with increased expression of antioxidant genes pointing out lower oxidative stress upon PARP10 silencing. Improved mitochondrial oxidative capacity coincided with increased AMPK activation. The silencing of PARP10 in MCF7 and CaCo2 cells decreased the proliferation rate that correlated with increased expression of anti-Warburg enzymes (Foxo1, PGC-1α, IDH2 and fumarase). By analyzing an online database we showed that lower PARP10 expression increases survival in gastric cancer. Furthermore, PARP10 expression decreased upon fasting, a condition that is characterized by increases in mitochondrial biogenesis. Finally, lower PARP10 expression is associated with increased fatty acid oxidation.
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Lai KP, Wan HT, Ng AHM, Li JW, Chan TF, Wong CKC. Transcriptomic and Functional Analyses on the Effects of Dioxin on Insulin Secretion of Pancreatic Islets and β-Cells. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:11390-11400. [PMID: 28880546 DOI: 10.1021/acs.est.7b02830] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this study, transcriptomic and Ingenuity Pathway Analysis (IPA) underlined that an ex-vivo TCDD treatment (0.1 nM) stimulated insulin-release in mouse pancreatic islets via the effect on the Akt-mTOR-p70S6K, AMPK and ERK1/2 pathways. Functional studies using both ex-vivo islets and the mouse β-cell-line (Min-6) validated the stimulatory effects of TCDD (0.1 and 1 nM) on basal-insulin secretion. At 0.1 nM TCDD treatment on Min-6, Western blot analysis showed activation of ERK1/2 and decreased expression of pyruvate dehydrogenase kinase (PDK). A reduction of PDK expression is associated with an increase of pyruvate dehydrogenase flux. This observation was supported by the detection of significantly higher cellular ATP levels, an increase of glucose-stimulated-insulin-secretion (GSIS), and an inhibition of the AMPK pathway. At 1 nM TCDD treatment on Min-6, significant inhibitions of the Akt-mTOR pathway, cellular ATP production, and GSIS were evident. The experimental studies in Min-6 supported the IPA of transcriptomic data in pancreatic islets. Collectively, TCDD treatment caused an elevated basal-insulin release in both islets and β-cell cultures. Moreover, our data revealed that the modulation of the Akt-mTOR-p70S6K, AMPK and ERK1/2 pathways might be an important component of the mechanism for the TCDD-perturbing effects on ATP production in β-cells in affecting insulin secretion.
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Affiliation(s)
- Keng Po Lai
- Department of Chemistry, City University of Hong Kong , Hong Kong SAR, China
| | - Hin Ting Wan
- Croucher Institute for Environmental Sciences, Partner State Key Laboratory of Environmental and Biological Analysis, Department of Biology, Hong Kong Baptist University , Hong Kong SAR, China
| | - Alice Hoi-Man Ng
- Croucher Institute for Environmental Sciences, Partner State Key Laboratory of Environmental and Biological Analysis, Department of Biology, Hong Kong Baptist University , Hong Kong SAR, China
| | - Jing Woei Li
- Department of Chemistry, City University of Hong Kong , Hong Kong SAR, China
- School of Life Sciences, Hong Kong Bioinformatics Centre, The Chinese University of Hong Kong , Hong Kong SAR, China
| | - Ting Fung Chan
- School of Life Sciences, Hong Kong Bioinformatics Centre, The Chinese University of Hong Kong , Hong Kong SAR, China
| | - Chris Kong-Chu Wong
- Croucher Institute for Environmental Sciences, Partner State Key Laboratory of Environmental and Biological Analysis, Department of Biology, Hong Kong Baptist University , Hong Kong SAR, China
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17
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Kubešová K, Trávníček Z, Dvořák Z. Pleiotropic effects of gold(I) mixed-ligand complexes of 9-deazahypoxanthine on transcriptional activity of receptors for steroid hormones, nuclear receptors and xenoreceptors in human hepatocytes and cell lines. Eur J Med Chem 2016; 121:530-540. [DOI: 10.1016/j.ejmech.2016.05.064] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 05/29/2016] [Accepted: 05/30/2016] [Indexed: 11/25/2022]
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18
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Kakizuka S, Takeda T, Komiya Y, Koba A, Uchi H, Yamamoto M, Furue M, Ishii Y, Yamada H. Dioxin-Produced Alteration in the Profiles of Fecal and Urinary Metabolomes: A Change in Bile Acids and Its Relevance to Toxicity. Biol Pharm Bull 2016; 38:1484-95. [PMID: 26424014 DOI: 10.1248/bpb.b15-00235] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study investigated dioxin-induced changes in metabolomes in pubertal rat excrement. The administration of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or restricting dietary intake (pair-fed group) markedly altered the metabolomic profile including lipids, hormones, and vitamins in the urine and feces. TCDD caused an increase in the fecal chenodeoxycholic acid and taurocholic acid content and in urinary adrenaline and 17β-estradiol, while the urinary melatonin level was reduced by TCDD. These changes were not observed in the pair-fed group. In accordance with the elevated level of fecal bile acids, TCDD reduced the intestinal expression of the apical sodium-dependent bile salt transporter, which plays a role in resorbing bile acids from the bile duct. In addition, CYP7A1, a rate-limiting enzyme for bile acid biosynthesis, was attenuated by TCDD treatment, although TCDD induced hepatic CYP8B1, an enzyme essential for cholic acid synthesis. Supplying cholic acid or chenodeoxycholic acid to TCDD-exposed rats tended to restore the TCDD-produced reduction in serum triglycerides, whereas no similar trend was observed in wasting syndrome and lipid accumulation in the liver. These results suggest that: 1) TCDD alters the circulating levels of bile acids and hormones via a mechanism distinct from an attenuation in dietary intake, although the majority of TCDD-induced changes in nutrient contents in the excrement is due to a reduction in food intake; and 2) TCDD facilitates the excretion of bile acids and disrupts their biosynthesis, resulting in the disturbance of lipid homeostasis.
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Affiliation(s)
- Saki Kakizuka
- Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University
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19
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Kubešová K, Dořičáková A, Trávníček Z, Dvořák Z. Mixed-ligand copper(II) complexes activate aryl hydrocarbon receptor AhR and induce CYP1A genes expression in human hepatocytes and human cell lines. Toxicol Lett 2016; 255:24-35. [PMID: 27180721 DOI: 10.1016/j.toxlet.2016.05.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 05/10/2016] [Accepted: 05/11/2016] [Indexed: 10/21/2022]
Abstract
The effects of four copper(II) mixed-ligand complexes [Cu(qui1)(L)]NO3·H2O (1-3) and [Cu(qui2)(phen)]NO3 (4), where qui1=2-phenyl-3-hydroxy-4(1H)-quinolinone, Hqui2=2-(4-amino-3,5-dichlorophenyl)-N-propyl-3-hydroxy-4(1H)-quinolinone-7-carboxamide, L=1,10-phenanthroline (phen) (1), 5-methyl-1,10-phenanthroline (mphen) (2), bathophenanthroline (bphen) (3), on transcriptional activities of steroid receptors, nuclear receptors and xenoreceptors have been studied. The complexes (1-4) did not influence basal or ligand-inducible activities of glucocorticoid receptor, androgen receptor, thyroid receptor, pregnane X receptor and vitamin D receptor, as revealed by gene reporter assays. The complexes 1 and 2 dose-dependently induced luciferase activity in stable gene reporter AZ-AhR cell line, and this induction was reverted by resveratrol, indicating involvement of aryl hydrocarbon receptor (AhR) in the process. The complexes 1, 2 and 3 induced CYP1A1 mRNA in LS180 cells and CYP1A1/CYP1A2 in human hepatocytes through AhR. Electrophoretic mobility shift assay EMSA showed that the complexes 1 and 2 transformed AhR in its DNA-binding form. Collectively, we demonstrate that the complexes 1 and 2 activate AhR and induce AhR-dependent genes in human hepatocytes and cancer cell lines. In conclusion, the data presented here might be of toxicological importance, regarding the multiple roles of AhR in human physiology and pathophysiology.
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Affiliation(s)
- Kateřina Kubešová
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University Olomouc, Šlechtitelů 27(,) CZ-783 71 Olomouc, Czech Republic
| | - Aneta Dořičáková
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University Olomouc, Šlechtitelů 27(,) CZ-783 71 Olomouc, Czech Republic
| | - Zdeněk Trávníček
- Department of Inorganic Chemistry, Faculty of Science, Palacký University, 17.listopadu 12, CZ-771 46 Olomouc, Czech Republic
| | - Zdeněk Dvořák
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University Olomouc, Šlechtitelů 27(,) CZ-783 71 Olomouc, Czech Republic.
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20
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Hwang HJ, Dornbos P, Steidemann M, Dunivin TK, Rizzo M, LaPres JJ. Mitochondrial-targeted aryl hydrocarbon receptor and the impact of 2,3,7,8-tetrachlorodibenzo-p-dioxin on cellular respiration and the mitochondrial proteome. Toxicol Appl Pharmacol 2016; 304:121-32. [PMID: 27105554 DOI: 10.1016/j.taap.2016.04.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 04/02/2016] [Accepted: 04/08/2016] [Indexed: 11/18/2022]
Abstract
The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor within the Per-Arnt-Sim (PAS) domain superfamily. Exposure to the most potent AHR ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), is associated with various pathological effects including metabolic syndrome. While research over the last several years has demonstrated a role for oxidative stress and metabolic dysfunction in AHR-dependent TCDD-induced toxicity, the role of the mitochondria in this process has not been fully explored. Our previous research suggested that a portion of the cellular pool of AHR could be found in the mitochondria (mitoAHR). Using a protease protection assay with digitonin extraction, we have now shown that this mitoAHR is localized to the inter-membrane space (IMS) of the organelle. TCDD exposure induced a degradation of mitoAHR similar to that of cytosolic AHR. Furthermore, siRNA-mediated knockdown revealed that translocase of outer-mitochondrial membrane 20 (TOMM20) was involved in the import of AHR into the mitochondria. In addition, TCDD altered cellular respiration in an AHR-dependent manner to maintain respiratory efficiency as measured by oxygen consumption rate (OCR). Stable isotope labeling by amino acids in cell culture (SILAC) identified a battery of proteins within the mitochondrial proteome influenced by TCDD in an AHR-dependent manner. Among these, 17 proteins with fold changes≥2 are associated with various metabolic pathways, suggesting a role of mitochondrial retrograde signaling in TCDD-mediated pathologies. Collectively, these studies suggest that mitoAHR is localized to the IMS and AHR-dependent TCDD-induced toxicity, including metabolic dysfunction, wasting syndrome, and hepatic steatosis, involves mitochondrial dysfunction.
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Affiliation(s)
- Hye Jin Hwang
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, United States; Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI 48824, United States
| | - Peter Dornbos
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, United States; Institute for Integrative Toxicology, Michigan State University, East Lansing, MI 48824-1319, United States
| | - Michelle Steidemann
- Institute for Integrative Toxicology, Michigan State University, East Lansing, MI 48824-1319, United States; Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, United States
| | - Taylor K Dunivin
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, United States
| | - Mike Rizzo
- Institute for Integrative Toxicology, Michigan State University, East Lansing, MI 48824-1319, United States; Cell and Molecular Biology Graduate Program, Michigan State University, East Lansing, MI 48824, United States
| | - John J LaPres
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, United States; Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI 48824, United States.
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22
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Cowens KR, Simpson S, Thomas WK, Carey GB. Polybrominated Diphenyl Ether (PBDE)-Induced Suppression of Phosphoenolpyruvate Carboxykinase (PEPCK) Decreases Hepatic Glyceroneogenesis and Disrupts Hepatic Lipid Homeostasis. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2015; 78:1437-49. [PMID: 26692069 DOI: 10.1080/15287394.2015.1098580] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Polybrominated diphenyl ethers (PBDE) are a class of flame-retardant chemicals that leach into the environment and enter the human body. PBDE have been shown to suppress activity of phosphoenolpyruvate carboxykinase (PEPCK), a key enzyme in fatty acid esterification via hepatic glyceroneogenesis. The objective of this investigation was to assess hepatic glyceroneogenesis and lipid metabolism in PBDE-treated rats. Male, weanling Wistar rats were gavaged daily for 28 d with 14 mg/kg body weight of either DE-71, a commercial PBDE mixture (treated), or corn oil (control). After a 48-h fast, rats were euthanized, blood was obtained, and livers were excised. Suppression of hepatic PEPCK activity by 40% was noted. Serum ketone bodies were elevated by 27% in treated rats compared to controls, while hepatic glyceroneogenesis as measured by (14)C-pyruvate incorporation into triglycerides was 41% lower in explants from treated rats compared to controls. Liver lipid content was 29% lower in treated animals compared to controls. Taken together, these findings suggest that DE-71-induced inhibition of hepatic PEPCK activity alters lipid metabolism by redirecting fatty acids away from esterification and storage toward ketone synthesis.
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Affiliation(s)
- Kylie R Cowens
- a Department of Molecular, Cellular, and Biomedical Sciences , University of New Hampshire , Durham , New Hampshire , USA
| | - Stephen Simpson
- a Department of Molecular, Cellular, and Biomedical Sciences , University of New Hampshire , Durham , New Hampshire , USA
| | - W Kelley Thomas
- a Department of Molecular, Cellular, and Biomedical Sciences , University of New Hampshire , Durham , New Hampshire , USA
| | - Gale B Carey
- a Department of Molecular, Cellular, and Biomedical Sciences , University of New Hampshire , Durham , New Hampshire , USA
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MacPherson L, Ahmed S, Tamblyn L, Krutmann J, Förster I, Weighardt H, Matthews J. Aryl hydrocarbon receptor repressor and TiPARP (ARTD14) use similar, but also distinct mechanisms to repress aryl hydrocarbon receptor signaling. Int J Mol Sci 2014; 15:7939-57. [PMID: 24806346 PMCID: PMC4057711 DOI: 10.3390/ijms15057939] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 04/23/2014] [Indexed: 12/16/2022] Open
Abstract
The aryl hydrocarbon receptor (AHR) regulates the toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The AHR repressor (AHRR) is an AHR target gene and functions as a ligand-induced repressor of AHR; however, its mechanism of inhibition is controversial. Recently, we reported that TCDD-inducible poly (ADP-ribose) polymerase (TiPARP; ARTD14) also acts as a repressor of AHR, representing a new player in the mechanism of AHR action. Here we compared the ability of AHRR- and TiPARP-mediated inhibition of AHR activity. TCDD increased AHRR mRNA levels and recruitment of AHRR to cytochrome P450 1A1 (CYP1A1) in MCF7 cells. Knockdown of TiPARP, but not AHRR, increased TCDD-induced CYP1A1 mRNA and AHR protein levels. Similarly, immortalized TiPARP−/− mouse embryonic fibroblasts (MEFs) and AHRR−/− MEFs exhibited enhanced AHR transactivation. However, unlike TiPARP−/− MEFs, AHRR−/− MEFs did not exhibit increased AHR protein levels. Overexpression of TiPARP in AHRR−/− MEFs or AHRRΔ8, the active isoform of AHRR, in TiPARP−/− MEFs reduced TCDD-induced CYP1A1 mRNA levels, suggesting that they independently repress AHR. GFP-AHRRΔ8 and GFP-TiPARP expressed as small diffuse nuclear foci in MCF7 and HuH7 cells. GFP-AHRRΔ8_Δ1-49, which lacks its putative nuclear localization signal, localized to both the nucleus and the cytoplasm, while the GFP-AHRRΔ8_Δ1-100 mutant localized predominantly in large cytoplasmic foci. Neither GFP-AHRRΔ8_Δ1-49 nor GFP-AHRRΔ8_Δ1-100 repressed AHR. Taken together, AHRR and TiPARP repress AHR transactivation by similar, but also different mechanisms.
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Affiliation(s)
- Laura MacPherson
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Shaimaa Ahmed
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Laura Tamblyn
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Jean Krutmann
- IUF-Leibniz Research Institute for Environmental Medicine gGmbH, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany.
| | - Irmgard Förster
- Immunology and Environment, Life and Medical Sciences (LIMES) Institute, University of Bonn, Carl-Troll-Straβe 31, 53115 Bonn, Germany.
| | - Heike Weighardt
- IUF-Leibniz Research Institute for Environmental Medicine gGmbH, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany.
| | - Jason Matthews
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON M5S 1A8, Canada.
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