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Dau PT, Ishibashi H, Tuyen LH, Sakai H, Hirano M, Kim EY, Iwata H. Assessment of binding potencies of polychlorinated biphenyls and polybrominated diphenyl ethers with Baikal seal and mouse constitutive androstane receptors: Comparisons across species and congeners. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:150631. [PMID: 34592282 DOI: 10.1016/j.scitotenv.2021.150631] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 09/23/2021] [Accepted: 09/23/2021] [Indexed: 06/13/2023]
Abstract
The present study evaluated the binding potencies (equilibrium dissociation constant: KD) of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) with the constitutive androstane receptor (CAR)_ligand binding domain (LBD) of the Baikal seal (bsCAR_LBD) and mouse (mCAR_LBD) using a surface plasmon resonance (SPR) biosensor. The binding affinities of individual congeners with mCAR_LBD tended to be higher than those with bsCAR_LBD but the differences were within the same order of magnitude. Notably, PBDE congeners showed higher binding affinities for both CAR_LBDs than PCB congeners. In silico docking simulations demonstrated that PBDEs had more non-covalent interactions with specific amino acid residues in both CAR_LBDs than PCBs, supporting the results of their binding affinities. Binding affinity comparisons among congeners revealed the structural requirements for higher binding; mono or di ortho-, tri meta-, and di para‑chlorine substitutions for PCBs, and di or tri ortho-, mono meta-, and di para‑bromine substitutions for PBDEs. The binding potencies of these congeners unlikely accounted for their previously reported CAR-mediated transactivation potencies, implying that their transactivation is regulated in a ligand-dependent, but a distinct manner from ligand binding. Risk assessment analysis showed that the KD values of individual PCB and PBDE congeners were 1-4 orders of magnitude higher than their respective hepatic concentrations in wild Baikal seal population.
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Affiliation(s)
- Pham Thi Dau
- Centre for Life Science Research, Faculty of Biology, VNU University of Science, 334 Nguyen Trai, Hanoi, Viet Nam.
| | - Hiroshi Ishibashi
- Graduate School of Agriculture, Ehime University, Matsuyama 790-8566, Japan
| | - Le Huu Tuyen
- Research Centre for Environmental Technology and Sustainable Development, VNU University of Science, 334 Nguyen Trai, Hanoi, Viet Nam
| | - Hiroki Sakai
- Division of Pharmacology, Yamaguchi University Graduate School of Medicine, Yamaguchi 755-8505, Japan
| | - Masashi Hirano
- Department of Bioscience, School of Agriculture, Tokai University, 9-1-1 Toroku, Higashi-ku, Kumamoto-shi, Kumamoto 862-8652, Japan
| | - Eun-Young Kim
- Department of Life and Nanopharmaceutical Science and Department of Biology, Kyung Hee University, Hoegi-Dong, Dongdaemun-Gu, Seoul 130-701, Republic of Korea
| | - Hisato Iwata
- Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama 790-8577, Japan.
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Travis SC, Pérez-Fuentetaja A, Aga DS. Evidence of continued exposure to legacy persistent organic pollutants in threatened migratory common terns nesting in the Great Lakes. ENVIRONMENT INTERNATIONAL 2020; 144:106065. [PMID: 32891920 DOI: 10.1016/j.envint.2020.106065] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 08/13/2020] [Accepted: 08/16/2020] [Indexed: 06/11/2023]
Abstract
Persistent organic pollutants (POPs) accumulate in the food web of the Great Lakes ecosystem, causing concern that these chemicals play a role in the decline of avian species such as colonial-nesting waterbirds. In this study, samples from four life stages of the common tern (Sterna hirundo), a threatened species in New York State, were collected post-mortem in the Buffalo-Niagara region (United States). Brains (n = 26) and livers (n =27) were analyzed for polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and the insecticide p,p'-dichlorodiphenyltrichloroethane (DDT) and its two metabolites p,p'-dichlorodiphenyldichloroethylene (DDE) and p,p'-dichlorodiphenyldichloroethane (DDD). Detectable concentrations of PCBs and PBDEs were observed in all samples; concentrations of total PCBs ranged from 5.59 to 2,490 ng/g wet weight (ww), total PBDEs ranged from 1.09 to 494 ng/g ww, and DDE metabolites ranged from 0.56 to 637 ng/g ww. Analysis of the primary food source for terns in the Buffalo-Niagara region, emerald shiners (Notropis atherinoides), revealed that all three classes of POPs had similar contaminant profiles in the fish to those in the brains and livers of tern samples. Overall, small chicks contained greater concentrations of pollutants than medium chicks and juveniles, likely from maternal loading to eggs. These results underline the persistence of these legacy contaminants in the Great Lakes, despite their banning, and their biomagnification in threatened species through food web interactions.
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Affiliation(s)
- Steven C Travis
- Department of Chemistry, University at Buffalo, The State University of New York Buffalo, New York, United States
| | - Alicia Pérez-Fuentetaja
- Department of Biology and Great Lakes Center, Buffalo State, The State University of New York, Buffalo, NY, United States
| | - Diana S Aga
- Department of Chemistry, University at Buffalo, The State University of New York Buffalo, New York, United States.
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3
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Kim JB, Zhao Q, Nguyen T, Pjanic M, Cheng P, Wirka R, Travisano S, Nagao M, Kundu R, Quertermous T. Environment-Sensing Aryl Hydrocarbon Receptor Inhibits the Chondrogenic Fate of Modulated Smooth Muscle Cells in Atherosclerotic Lesions. Circulation 2020; 142:575-590. [PMID: 32441123 DOI: 10.1161/circulationaha.120.045981] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Smooth muscle cells (SMC) play a critical role in atherosclerosis. The Aryl hydrocarbon receptor (AHR) is an environment-sensing transcription factor that contributes to vascular development, and has been implicated in coronary artery disease risk. We hypothesized that AHR can affect atherosclerosis by regulating phenotypic modulation of SMC. METHODS We combined RNA-sequencing, chromatin immunoprecipitation followed by sequencing, assay for transposase-accessible chromatin using sequencing, and in vitro assays in human coronary artery SMCs, with single-cell RNA-sequencing, histology, and RNAscope in an SMC-specific lineage-tracing Ahr knockout mouse model of atherosclerosis to better understand the role of AHR in vascular disease. RESULTS Genomic studies coupled with functional assays in cultured human coronary artery SMCs revealed that AHR modulates the human coronary artery SMC phenotype and suppresses ossification in these cells. Lineage-tracing and activity-tracing studies in the mouse aortic sinus showed that the Ahr pathway is active in modulated SMCs in the atherosclerotic lesion cap. Furthermore, single-cell RNA-sequencing studies of the SMC-specific Ahr knockout mice showed a significant increase in the proportion of modulated SMCs expressing chondrocyte markers such as Col2a1 and Alpl, which localized to the lesion neointima. These cells, which we term "chondromyocytes," were also identified in the neointima of human coronary arteries. In histological analyses, these changes manifested as larger lesion size, increased lineage-traced SMC participation in the lesion, decreased lineage-traced SMCs in the lesion cap, and increased alkaline phosphatase activity in lesions in the Ahr knockout in comparison with wild-type mice. We propose that AHR is likely protective based on these data and inference from human genetic analyses. CONCLUSIONS Overall, we conclude that AHR promotes the maintenance of lesion cap integrity and diminishes the disease-related SMC-to-chondromyocyte transition in atherosclerotic tissues.
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Affiliation(s)
- Juyong Brian Kim
- Division of Cardiovascular Medicine (J.B.K., Q.Z., T.N., M.P., P.C., R.W., S.T., M.N., R.K., T.Q.), Stanford University School of Medicine, CA.,Cardiovascular Institute (J.B.K., P.C., R.W., T.Q.), Stanford University School of Medicine, CA
| | - Quanyi Zhao
- Division of Cardiovascular Medicine (J.B.K., Q.Z., T.N., M.P., P.C., R.W., S.T., M.N., R.K., T.Q.), Stanford University School of Medicine, CA
| | - Trieu Nguyen
- Division of Cardiovascular Medicine (J.B.K., Q.Z., T.N., M.P., P.C., R.W., S.T., M.N., R.K., T.Q.), Stanford University School of Medicine, CA
| | - Milos Pjanic
- Division of Cardiovascular Medicine (J.B.K., Q.Z., T.N., M.P., P.C., R.W., S.T., M.N., R.K., T.Q.), Stanford University School of Medicine, CA
| | - Paul Cheng
- Division of Cardiovascular Medicine (J.B.K., Q.Z., T.N., M.P., P.C., R.W., S.T., M.N., R.K., T.Q.), Stanford University School of Medicine, CA.,Cardiovascular Institute (J.B.K., P.C., R.W., T.Q.), Stanford University School of Medicine, CA
| | - Robert Wirka
- Division of Cardiovascular Medicine (J.B.K., Q.Z., T.N., M.P., P.C., R.W., S.T., M.N., R.K., T.Q.), Stanford University School of Medicine, CA.,Cardiovascular Institute (J.B.K., P.C., R.W., T.Q.), Stanford University School of Medicine, CA
| | - Stanislao Travisano
- Division of Cardiovascular Medicine (J.B.K., Q.Z., T.N., M.P., P.C., R.W., S.T., M.N., R.K., T.Q.), Stanford University School of Medicine, CA
| | - Manabu Nagao
- Division of Cardiovascular Medicine (J.B.K., Q.Z., T.N., M.P., P.C., R.W., S.T., M.N., R.K., T.Q.), Stanford University School of Medicine, CA
| | - Ramendra Kundu
- Division of Cardiovascular Medicine (J.B.K., Q.Z., T.N., M.P., P.C., R.W., S.T., M.N., R.K., T.Q.), Stanford University School of Medicine, CA
| | - Thomas Quertermous
- Division of Cardiovascular Medicine (J.B.K., Q.Z., T.N., M.P., P.C., R.W., S.T., M.N., R.K., T.Q.), Stanford University School of Medicine, CA.,Cardiovascular Institute (J.B.K., P.C., R.W., T.Q.), Stanford University School of Medicine, CA
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Ronis MJ, Watt J, Pulliam CF, Williams AE, Alund AW, Haque E, Gadupudi GS, Robertson LW. Skeletal toxicity resulting from exposure of growing male rats to coplanar PCB 126 is associated with disruption of calcium homeostasis and the GH-IGF-1 axis and direct effects on bone formation. Arch Toxicol 2019; 94:389-399. [PMID: 31820026 DOI: 10.1007/s00204-019-02645-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 12/04/2019] [Indexed: 12/13/2022]
Abstract
Skeletal toxicity has been reported following exposure to polychlorinated biphenyl (PCB) mixtures. However, molecular mechanisms remain poorly understood. We exposed groups of male 4-5-week-old Sprague-Dawley rats to 3,3', 4, 4', 5-pentachlorobiphenyl (PCB 126), a dioxin-like coplanar PCB congener by a single i.p. injection of 5 µmol/kg in soy oil vehicle or vehicle alone. After 4 weeks, rats were euthanized. PCB exposure resulted in hypocalcemia (P < 0.05) and significant increases in serum PTH without changes in serum phosphorous. Hyperparathyroidism was accompanied by increased expression of mRNAs of vitamin D3 metabolizing cytochrome P450 enzymes CYP27B1 and CYP24 in the kidney (P < 0.05). PCB exposure also reduced body weight, serum IGF-1, and hepatic expression of mRNAs encoding the male-specific GH-pattern-regulated CYP2C11 and CYP3A2 relative to controls (P < 0.05). PCB exposure reduced long bone length, diameter, and surface area, but increased trabecular thickness and volume (P < 0.05). Serum osteocalcin (P < 0.05), a marker and a regulator of bone formation, was reduced, but PCB exposure had no effect on the bone resorption marker RatLaps. Exposure of human intestinal Caco-2 cells to 10-100 nM PCB 126 in the presence of vitamin D3 resulted in inhibition of mRNAs for the calcium transporters TRPV6 and PMCA1b (P < 0.05). In addition, PCB 126 suppressed osteoblastogenesis in primary bone marrow mesenchymal stem cell cultures which was blunted by the AhR antagonist CH-223191. These data provide novel evidence that skeletal toxicity after exposure to PCB 126 is a result of disruption of calcium homeostasis and the GH-IGF-1 axis, and involves direct AhR-mediated effects on bone formation.
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Affiliation(s)
- Martin J Ronis
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center-New Orleans, 1901 Perdido Str., New Orleans, LA, 70112, USA.
| | - James Watt
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center-New Orleans, 1901 Perdido Str., New Orleans, LA, 70112, USA
| | - Casey F Pulliam
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center-New Orleans, 1901 Perdido Str., New Orleans, LA, 70112, USA
| | - Ashlee E Williams
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center-New Orleans, 1901 Perdido Str., New Orleans, LA, 70112, USA
| | - Alexander W Alund
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Ezazul Haque
- IDGP in Human Toxicology and Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA, USA
| | - Gopi S Gadupudi
- IDGP in Human Toxicology and Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA, USA
| | - Larry W Robertson
- IDGP in Human Toxicology and Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA, USA
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5
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Morais CM, Shore RF, Pereira MG, Martin FL. Assessing Binary Mixture Effects from Genotoxic and Endocrine Disrupting Environmental Contaminants Using Infrared Spectroscopy. ACS OMEGA 2018; 3:13399-13412. [PMID: 30411037 PMCID: PMC6217637 DOI: 10.1021/acsomega.8b01916] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 10/04/2018] [Indexed: 05/15/2023]
Abstract
Benzo[a]pyrene (B[a]P), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) are persistent contaminants and concern has arisen over co-exposure of organisms when the chemicals exist in mixtures. Herein, attenuated total reflection Fourier transform infrared spectroscopy was used to identify biochemical alterations induced in cells by single and binary mixtures of these environmental chemicals. It was also investigated as a method to identify if interactions are occurring in mixtures and as a possible tool to predict mixture effects. Mallard fibroblasts were treated with single and binary mixtures of B[a]P, PCB126, PCB153, BDE47, and BDE209. Comparison of observed spectra from cells treated with binary mixtures with expected additive spectra, which were created from individual exposure spectra, indicated that in many areas of the spectrum, less-than-additive binary mixture effects may occur. However, possible greater-than-additive alterations were identified in the 1650-1750 cm-1 lipid region and may demonstrate a common mechanism of B[a]P and PCBs or PBDEs, which can enhance toxicity in mixtures.
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Affiliation(s)
- Camilo
L. M. Morais
- School
of Pharmacy and Biomedical Sciences, University
of Central Lancashire (UCLan), Preston PR1 2HE, U.K.
| | - Richard F. Shore
- Centre
of Ecology & Hydrology, Lancaster Environment
Centre, Lancaster LA1 4AP, U.K.
| | - M. Glória Pereira
- Centre
of Ecology & Hydrology, Lancaster Environment
Centre, Lancaster LA1 4AP, U.K.
| | - Francis L. Martin
- School
of Pharmacy and Biomedical Sciences, University
of Central Lancashire (UCLan), Preston PR1 2HE, U.K.
- E-mail:
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6
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Prenatal low dosage dioxin (TCDD) exposure impairs cochlear function resulting in auditory neuropathy. Hear Res 2015; 331:7-12. [PMID: 26464051 DOI: 10.1016/j.heares.2015.09.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 09/02/2015] [Accepted: 09/28/2015] [Indexed: 11/20/2022]
Abstract
2,3,7,8-tetrachorodibenzo-p-dioxin (TCDD), a ubiquitous and persistent environmental contaminant, is a potent teratogen. Whereas developmental TCDD toxicity is mediated by the aryl hydrocarbon receptor (AhR), the normal function of the AhR is poorly understood. We tested whether dioxin exposure during a critical period of hair cell development disrupts cochlear function in three mouse strains, (C57BL6, BalbC, and CBA) that contain high affinity AhR-b alleles. C57BL/6, BalbC, and CBA dams were exposed to 500 ng/kg TCDD or olive oil (vehicle) on embryonic day 12 by gavage. Cochlear function was analyzed at 1.5 months of age by measuring 1) auditory brainstem response (ABRs) to tone pips from 5.6 to 30 kHz, and 2) distortion-product otoacoustic emissions (DPOAEs) evoked by primaries with f2 at the same frequency values. Cochlear threshold sensitivity following TCDD exposure was significantly elevated in both female and male mice in the C57BL/6 strain, carrying the Ahb-1 allele, but not significantly elevated in the BalbC or CBA strains, carrying the Ahb-2 allele. These ABR threshold deficits in mice carrying the Ahb-1 allele parallels the cleft palate incidence to higher TCDD exposures, suggesting that ABR testing could serve as a sensitive indicator of TCDD toxicity in at-risk children. Moreover, DPOAEs were not affected following TCDD exposure in any of the mouse strains, suggesting that following TCDD exposure mice with the Ahb-1 allele exhibit a mild auditory neuropathy. The causes of many auditory neuropathies are unknown, yet a developmental exposure to dioxin may be a risk factor for this condition.
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Furness SGB, Whelan F. The pleiotropy of dioxin toxicity--xenobiotic misappropriation of the aryl hydrocarbon receptor's alternative physiological roles. Pharmacol Ther 2009; 124:336-53. [PMID: 19781569 DOI: 10.1016/j.pharmthera.2009.09.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 09/01/2009] [Indexed: 10/20/2022]
Abstract
The aryl hydrocarbon receptor is a signal regulated transcription factor that has best been characterised as regulating the xenobiotic response to a variety of planar aromatic hydrocarbons. There is compelling evidence that it mediates most, if not all, of the toxic effects of dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin). Dioxin exposure results in a wide variety of toxic outcomes including severe wasting syndrome, chloracne, thymic involution, severe immune suppression, reduced fertility, hepatotoxicity, teratogenicity, tumour promotion and death. The pleiotropy of toxic outcomes implies the disruption of a wide range of normal physiological functions. The aryl hydrocarbon receptor has developmentally restricted expression as well as developmental defects in gene-targeted mice. It has a wide range of target genes that do not fit into the classical xenobiotic metabolising gene battery and has recently been shown to interact with NF-kappa B and the estrogen receptor. There is also evidence for its activation in the absence of exogenous ligand, all of which point to various roles outside xenobiotic metabolism. Ligands so far identified display differential activation potential with respect to receptor activity. This article addresses activities of the aryl hydrocarbon receptor that are outside the xenobiotic response. Known physiological roles are discussed as well as how their disruption contributes to the pleiotropic toxicity of TCDD.
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Affiliation(s)
- Sebastian G B Furness
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia.
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8
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Bemis JC, Alejandro NF, Nazarenko DA, Brooks AI, Baggs RB, Gasiewicz TA. TCDD-induced alterations in gene expression profiles of the developing mouse paw do not influence morphological differentiation of this potential target tissue. Toxicol Sci 2006; 95:240-8. [PMID: 17035482 DOI: 10.1093/toxsci/kfl132] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The aryl-hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that mediates the toxicity of certain halogenated aromatic hydrocarbons including 2,3,7,8-tetra-chlorodibenzo-p-dioxin (TCDD). These compounds are potent developmental toxicants that can alter gene expression and disrupt processes of proliferation and differentiation. It has not yet been determined which tissues during development are most sensitive to these compounds, nor which genes are directly associated with the toxicities. We developed a transgenic (TG) mouse model to delineate the temporal and spatial context of transcriptionally active AhR by utilizing a dioxin responsive element-linked LacZ reporter system. The present study focuses on the pattern of TCDD-induced transgene expression localized to the footpad and digits of the paws between gestational days (GD) 13 and 18. Paw morphology was evaluated at several developmental stages following TCDD exposure. Gene expression profiles acquired by microarray technology were evaluated in the paws of fetuses exposed at GD 14.5. The results showed that TCDD exposure in utero induced LacZ expression in the developing paws. This expression appeared to be localized to the mesenchymal cell layer. Gross morphological changes were not observed in the paws prior to or after birth following TCDD exposure in utero. However, significant alterations in gene expression profiles in the developing paws were observed at 24 h following TCDD exposure in utero. These results indicate that the developing paw is a target tissue of TCDD in terms of altered gene expression, further validating the use of this AhR responsive reporter gene TG mouse model in studying AhR ligand-mediated responsiveness. However, the linkage of these changes to detectable biological outcomes in the paw remains unclear.
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Affiliation(s)
- Jeffrey C Bemis
- Department of Environmental Medicine, Rochester, New York 14642, USA
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Noguerol TN, Boronat S, Casado M, Raldúa D, Barceló D, Piña B. Evaluating the interactions of vertebrate receptors with persistent pollutants and antifouling pesticides using recombinant yeast assays. Anal Bioanal Chem 2006; 385:1012-9. [PMID: 16705413 DOI: 10.1007/s00216-006-0476-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 03/31/2006] [Accepted: 04/06/2006] [Indexed: 10/24/2022]
Abstract
The development of in vitro methods for screening potentially harmful biological activities of new compounds is an extremely important way to increase not only their intrinsic environmental safety, but also the public perception of the safety standards associated with them. In this work we use two yeast systems to test the ability of different chemicals to bind and activate two vertebrate receptors which are intimately related to adverse biological effects of pollution in exposed fauna: the estrogen receptor (ER) and the aryl hydrocarbon receptor (AhR). The panel of compounds analysed here includes well-known pollutants, like PCBs, pp'-DDT and hexachlorobenzene, together with the less-known, emerging putative pollutants, such as Sea-Nine, Irgarol and diuron. Results show the ability of some of these compounds to interact with one or both receptors, provide hints about the relationship between structure and activity, and suggest mechanistic explanations for the biological activities already described in whole-animal experiments. In addition, we show that AhR may have an intrinsic ligand promiscuity comparable to that of ER, a feature not fully appreciated in the past due to the technical difficulties involved with testing highly lipophilic substances in yeast-based assays.
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Affiliation(s)
- Tania-Noelia Noguerol
- Department of Molecular Biology, Institut de Biologia Molecular de Barcelona, CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain
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10
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Henry EC, Bemis JC, Henry O, Kende AS, Gasiewicz TA. A potential endogenous ligand for the aryl hydrocarbon receptor has potent agonist activity in vitro and in vivo. Arch Biochem Biophys 2006; 450:67-77. [PMID: 16545771 DOI: 10.1016/j.abb.2006.02.008] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2006] [Revised: 02/07/2006] [Accepted: 02/12/2006] [Indexed: 10/24/2022]
Abstract
The aryl hydrocarbon receptor (AhR) is best known as a mediator of toxicity of a diverse family of xenobiotic chemicals such as dioxins and PCBs. However, many naturally occurring compounds also activate AhR. One such compound, 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE), was isolated from tissue and found to be potent in preliminary tests [J. Song, M. Clagett-Dame, R.E. Peterson, M.E. Hahn, W.M. Westler, R.R. Sicinski, H.F. DeLuca, Proc. Natl. Acad. Sci. USA 99 (2002) 14694-14699]. We have synthesized ITE and [(3)H]ITE and further evaluated its AhR activity in several in vitro and in vivo assays in comparison with the toxic ligand, TCDD. AhR in Hepa1c1c7 cell cytosol bound [(3)H]ITE with high affinity and the AhR.ITE complex formed in vitro bound dioxin response element (DRE) oligonucleotide as potently as TCDD.AhR. In cells treated with ITE, nuclear translocation of AhR, and induction of CYP1A1 protein and of a DRE-dependent luciferase reporter gene were observed. ITE administered to pregnant DRE-LacZ transgenic mice activated fetal AhR, observed as X-gal staining in the same sites as in TCDD-treated mice. However, unlike TCDD, ITE did not induce cleft palate or hydronephrosis. TCDD but not ITE induced thymic atrophy in young adult mice, but both ITE and TCDD caused similar loss of cells and alterations of cell profiles in cultured fetal thymi. These data demonstrate that ITE is a potent AhR agonist in cell extracts, cultured cells, and intact animals, but does not cause the toxicity associated with the more stable xenobiotic ligand, TCDD.
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Affiliation(s)
- E C Henry
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, NY 14642, USA.
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