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Wang M, Luo N, Gao Y, Li G, An T. Pyrene and its derivatives increase lung adverse effects by activating aryl hydrocarbon receptor transcription. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 916:170030. [PMID: 38220008 DOI: 10.1016/j.scitotenv.2024.170030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 12/27/2023] [Accepted: 01/07/2024] [Indexed: 01/16/2024]
Abstract
Derivatives of polycyclic aromatic hydrocarbons (PAHs) pose significant threat to environment and human health due to their widespread and potential hazards. However, adverse effects and action mechanisms of PAH derivatives on human health have not been attempted yet. Herein, we chose pyrene and its derivatives (1-hydroxypyrene, 1-nitropyrene, and 1-methylpyrene) to investigate adverse effect mechanism to human lungs using in vitro and in vivo methods. Results showed that pyrene derivatives have higher lung health risks than original pyrene. They can activate AhR, subsequently affecting expression of downstream target genes CYP1A1 and CYP1B1. The binding energies of pyrene and its derivatives ranged from -16.07 to -27.25 kcal/mol by molecular dynamics simulations, implying that pyrene and its derivatives acted as agonists of AhR and increased adverse effects on lungs. Specifically, 1-nitropyrene exhibited stabler binding conformation and stronger AhR expression. In addition, sensitivity of pyrene and its derivatives to AhR activation was attributed to type and number of key amino acids in AhR, that is, pyrene (Leu293), 1-nitropyrene (Cys333, Met348, and Val381), 1-hydroxypyrene (Leu293 and Phe287), and 1-methylpyrene (Met348). In summary, we provide a universal approach for understanding action mechanisms of PAH derivatives on human health, and their adverse effects should be taken seriously.
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Affiliation(s)
- Mei Wang
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Na Luo
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Yanpeng Gao
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Guiying Li
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Taicheng An
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China.
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Johnson H, Dubiel J, Collins CH, Eriksson ANM, Lu Z, Doering JA, Wiseman S. Assessing the Toxicity of Benzotriazole Ultraviolet Stabilizers to Fishes: Insights into Aryl Hydrocarbon Receptor-Mediated Effects. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:110-120. [PMID: 38112502 PMCID: PMC10785820 DOI: 10.1021/acs.est.3c06117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 11/30/2023] [Accepted: 12/01/2023] [Indexed: 12/21/2023]
Abstract
Benzotriazole ultraviolet stabilizers (BUVSs) are chemicals used to mitigate UV-induced damage to manufactured goods. Their presence in aquatic environments and biota raises concerns, as certain BUVSs activate the aryl hydrocarbon receptor (AhR), which is linked to adverse effects in fish. However, potencies of BUVSs as AhR agonists and species sensitivities to AhR activation are poorly understood. This study evaluated the toxicity of three BUVSs using embryotoxicity assays. Zebrafish (Danio rerio) embryos exposed to BUVSs by microinjection suffered dose-dependent increases in mortality, with LD50 values of 4772, 11 608, and 56 292 ng/g-egg for UV-P, UV-9, and UV-090, respectively. The potencies and species sensitivities to AhR2 activation by BUVSs were assessed using a luciferase reporter gene assay with COS-7 cells transfected with the AhR2 of zebrafish and eight other fishes. The rank order of potency for activation of the AhR2 from all nine species was UV-P > UV-9 > UV-090. However, AhR2s among species differed in sensitivities to activation by up to 100-fold. An approximate reversed rank order of species sensitivity was observed compared to the rank order of sensitivity to 2,3,7,8-tetrachlorodibenzo[p]dioxin, the prototypical AhR agonist. Despite this, a pre-existing quantitative adverse outcome pathway linking AhR activation to embryo lethality could predict embryotoxicities of BUVSs in zebrafish.
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Affiliation(s)
- Hunter
M. Johnson
- Department
of Biological Science, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada
| | - Justin Dubiel
- Department
of Biological Science, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada
| | - Cameron H. Collins
- Department
of Environmental Sciences, College of the Coast and Environmental, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Andreas N. M. Eriksson
- Department
of Biological Science, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada
| | - Zhe Lu
- Institut
des Sciences de la Mer de Rimouski, Université du Québec
à Rimouski, Rimouski, Québec G5L 3A1, Canada
| | - Jon A. Doering
- Department
of Biological Science, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada
- Department
of Environmental Sciences, College of the Coast and Environmental, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Steve Wiseman
- Department
of Biological Science, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada
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3
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Wang R, Zhang C, Li X, Sha W, Xue Z, Zhou Z, Ma Y, Zhu S, Guo Z, Zhao B, Zhang W. Toxicological evaluation of TBBPA by common carp (Cyprinus carpio) about the in vivo/vitro disturbance of the AHR pathway. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 904:166622. [PMID: 37647967 DOI: 10.1016/j.scitotenv.2023.166622] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Revised: 08/24/2023] [Accepted: 08/25/2023] [Indexed: 09/01/2023]
Abstract
Tetrabromobisphenol A (TBBPA) is a widely used plastic additive with high bioaccumulation potential and toxicity on both humans and wildlife. Currently, research on its ecotoxicity and the underlying mechanism is limited. Using common carp (Cyprinus carpio), we evaluated the toxicity of TBBPA, especially focusing on its alteration of a key metabolism-related pathway aryl hydrocarbon receptor (AHR), using in vivo/vitro assays and in silico simulation. The 96 h LC50 of TBBPA of common carp was 4.2 mg/L and belonged to the acute toxic level II. The bioaccumulation potential of TBBPA follows the role of liver > gill > brain and varies between 3- and 14-day exposure. On the AHR pathway respect, as expected, the metabolism-related cyp1a1 and cyp1b1 were upregulated in the liver and brain. Ahr2, the receptor, was also upregulated in the brain under TBBPA exposure. The alteration of gene expression was tissue-specific while the difference between 3- or 14-day exposure was minor. AHR inhibition assay indicated the 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD)-induced AHR transactivation can be inhibited by TBBPA suggesting it is not a potent agonist but a competitive antagonist. In silico analysis indicated TBBPA can be successfully docked into the binding cavity with similar poses but still have AHR-form-specific interactions. Molecular dynamics simulation proved TBBPA can be more flexible than the coplanar ligand TCDD, especially in ccaAHR1b with greater root-mean-square deviation (RMSD), of which TCDD-induced transactivation seemed not to be blocked by TBBPA. This research increased the understanding of TBBPA toxicity and alteration of the AHR pathway, and pointed out the need to perform additional toxicology evaluation of emerging contaminants, especially on non-model species.
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Affiliation(s)
- Renjun Wang
- College of Life Sciences, Qufu Normal University, Qufu, Shandong 273165, China
| | - Chen Zhang
- College of Life Sciences, Qufu Normal University, Qufu, Shandong 273165, China
| | - Xingyang Li
- College of Life Sciences, Qufu Normal University, Qufu, Shandong 273165, China
| | - Weilai Sha
- College of Life Sciences, Qufu Normal University, Qufu, Shandong 273165, China
| | - Zhenhong Xue
- College of Life Sciences, Qufu Normal University, Qufu, Shandong 273165, China
| | - Zhiguang Zhou
- State Environmental Protection Key Laboratory of Dioxin Pollution Control, National Research Center for Environmental Analysis and Measurement, Beijing 100029, China
| | - Yongchao Ma
- Department of Medicine, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Shuyun Zhu
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, Shandong 273165, China
| | - Zitong Guo
- College of Life Sciences, Qufu Normal University, Qufu, Shandong 273165, China
| | - Bin Zhao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Wanglong Zhang
- College of Life Sciences, Qufu Normal University, Qufu, Shandong 273165, China.
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Cary TL, Karasov WH. Larval Exposure to Polychlorinated Biphenyl-126 Led to a Long-Lasting Decrease in Immune Function in Postmetamorphic Juvenile Northern Leopard Frogs, Lithobates pipiens. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2022; 41:81-94. [PMID: 34807990 DOI: 10.1002/etc.5233] [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: 02/02/2021] [Revised: 10/01/2021] [Accepted: 10/17/2021] [Indexed: 06/13/2023]
Abstract
Amphibian populations are decreasing worldwide, and pollution is a contributing factor. Polychlorinated biphenyls (PCBs) are a class of persistent organic pollutants known to exert immunotoxicity. To assess impacts of PCBs on frogs, we exposed Lithobates pipiens tadpoles to a diet of PCB-126 (0-5 ng PCB-126/g wet food) through metamorphic climax. Postmetamorphic frogs were immunized with keyhole limpet hemocyanin (KLH); then production of KLH-specific IgY, as well as total IgY and IgM, was measured (Trial I). A second larval study (0 and 7.3 ng PCB-126/g wet food) was performed to investigate whether PCB altered antigenic responses in prometamorphic tadpoles (Gosner Stage 36-39), and to measure the innate immune response of postmetamorphic frogs (Trial II). After larval PCB-126 exposure, both KLH-specific IgY levels and complement activity were reduced. Because postmetamorphic frogs carried a body burden of PCB-126 (2.4 ng/g or less), we wanted to determine whether the effect on immune response was due to larval exposure or to the resulting body burden as frogs. To test this, we reared tadpoles under control conditions (no PCB), and limited PCB exposure to postmetamorphosis only by injecting 2-week-old frogs with 10 ng PCB-126/g (Trial III). The resulting body burden (3.4 ng/g) was similar to that of frogs in Trial I, but we no longer detected suppression of KLH-specific IgY or hemolytic activity. These results suggest life-stage-specific immune responses; however, because we administered PCB-126 differently between trials, it is premature to conclude that these differences are intrinsically life stage dependent, and further study is warranted. Regardless, our study demonstrated a long-lasting effect of larval PCB-126 exposure that persisted through metamorphosis and suppressed frog immunity. Environ Toxicol Chem 2022;41:81-94. © 2021 SETAC.
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Affiliation(s)
- Tawnya L Cary
- Department of Zoology, University of Wisconsin, Madison, Wisconsin, USA
- Department of Biology, Beloit College, Beloit, Wisconsin, USA
| | - William H Karasov
- Department of Zoology, University of Wisconsin, Madison, Wisconsin, USA
- Department of Forest & Wildlife Ecology, University of Wisconsin, Madison, Wisconsin, USA
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Kazzaz SA, Giani Tagliabue S, Franks DG, Denison MS, Hahn ME, Bonati L, Powell WH. An aryl hydrocarbon receptor from the caecilian Gymnopis multiplicata suggests low dioxin affinity in the ancestor of all three amphibian orders. Gen Comp Endocrinol 2020; 299:113592. [PMID: 32858041 PMCID: PMC7771225 DOI: 10.1016/j.ygcen.2020.113592] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 07/31/2020] [Accepted: 08/18/2020] [Indexed: 11/18/2022]
Abstract
The aryl hydrocarbon receptor (AHR) plays pleiotropic roles in the development and physiology of vertebrates in conjunction with xenobiotic and endogenous ligands. It is best known for mediating the toxic effects of dioxin-like pollutants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). While most vertebrates possess at least one AHR that binds TCDD tightly, amphibian AHRs bind TCDD with very low affinity. Previous analyses of AHRs from Xenopus laevis (a frog; order Anura) and Ambystoma mexicanum (a salamander; order Caudata) identified three amino acid residues in the ligand-binding domain (LBD) that underlie low-affinity binding. In X. laevis AHR1β, these are A354, A370, and N325. Here we extend the analysis of amphibian AHRs to the caecilian Gymnopis multiplicata, representing the remaining extant amphibian order, Gymnophiona. G. multiplicata AHR groups with the monophyletic vertebrate AHR/AHR1 clade. The LBD includes all three signature residues of low TCDD affinity, and a structural homology model suggests that its architecture closely resembles those of other amphibians. In transactivation assays, the EC50 for reporter gene induction by TCDD was 17.17 nM, comparable to X. laevis AhR1β (26.23 nM) and Ambystoma AHR (34.09 nM) and dramatically higher than mouse AhR (0.13 nM), a trend generally reflected in direct measures of TCDD binding. These shared properties distinguish amphibian AHRs from the high-affinity proteins typical of both vertebrate groups that diverged earlier (teleost fish) and those that appeared more recently (other tetrapods). These findings suggest the hypothesis that AHRs with low TCDD affinity represent a characteristic that evolved in a common ancestor of all three extant amphibian groups.
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Affiliation(s)
- Sarah A Kazzaz
- Biology Department, Kenyon College, Gambier, OH 43022, USA
| | - Sara Giani Tagliabue
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milan 20126, Italy
| | - Diana G Franks
- Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Michael S Denison
- Department of Environmental Toxicology, University of California-Davis, Davis, CA 95616, USA
| | - Mark E Hahn
- Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Laura Bonati
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milan 20126, Italy
| | - Wade H Powell
- Biology Department, Kenyon College, Gambier, OH 43022, USA.
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Zhang W, Xie HQ, Li Y, Zou X, Xu L, Ma D, Li J, Ma Y, Jin T, Hahn ME, Zhao B. Characterization of the Aryl Hydrocarbon Receptor (AhR) Pathway in Anabas testudineus and Mechanistic Exploration of the Reduced Sensitivity of AhR2a. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:12803-12811. [PMID: 31566365 PMCID: PMC6832778 DOI: 10.1021/acs.est.9b04181] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Field investigations have revealed the ability of the climbing perch Anabas testudineus to survive in highly contaminated water bodies. The aryl hydrocarbon receptor (AhR) pathway is vital in mediating the toxicity of aromatic hydrocarbon contaminants, and genotypic variation in the AhR can confer resistance to these contaminants. Thus, we characterized the AhR pathway in A. testudineus in order to understand the mechanism(s) underlying the resistance of this species to contaminants and to broaden current knowledge on teleost AhR. In A. testudineus, four AhRs, two AhR nuclear translocators (ARNTs), and one AhR repressor (AhRR) were found. Transient transfection assays revealed that AhR1a, AhR1b, and AhR2b were functional, whereas AhR2a was poorly activated by the potent agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Two ARNTs (partner of AhR) and one AhRR (repressor of AhR) all were functional with each of the active AhR. As a major form, the insensitivity of AhR2a might serve as a potential mechanism for A. testudineus' reduced sensitivity to severe contamination. We explored the key residues that may account for AhR2a's insensitivity in silico and then functionally validated them in vitro. Two sites (VCS322-324, M370) in its ligand-binding domain (LBD) were proved critical for its sensitivity to TCDD. This systematic exploration of the AhR pathway showed that most members have maintained their traditional functions as expected, whereas a nonfunctionalization event has occurred for AhR2a.
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Affiliation(s)
- Wanglong Zhang
- 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
| | - Yunping Li
- 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
| | - Xianghui Zou
- School of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou 521041, 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
| | - Dan Ma
- 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
| | - Jiao Li
- 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
| | - Yongchao Ma
- 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
| | - Tao Jin
- China National Genebank-Shenzhen, BGI-Shenzhen, Shenzhen 518083, China
- BGI-Qingdao, Qingdao 266510, China
| | - Mark E. Hahn
- Biology Department, Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA 02543, USA
- Boston University Superfund Research Program, Boston University, Boston, MA 02118, USA
| | - 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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Bak SM, Nakata H, Koh DH, Yoo J, Iwata H, Kim EY. In vitro and in silico AHR assays for assessing the risk of heavy oil-derived polycyclic aromatic hydrocarbons in fish. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 181:214-223. [PMID: 31195230 DOI: 10.1016/j.ecoenv.2019.06.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 05/31/2019] [Accepted: 06/02/2019] [Indexed: 06/09/2023]
Abstract
In the aftermath of the Great East Japan Earthquake of March 11, 2011, marine fish in Kesennuma Bay, Japan, have been contaminated with heavy oil containing polycyclic aromatic hydrocarbons (PAHs). To estimate the risk of six PAHs (benzo[α]pyrene, dibenzothiophene, phenanthrene, 2,3,5-trimethylnaphthalene, acenaphthene, and 1-methylphenanthrene), which have been detected at high levels in the tissues of fish from Kesennuma Bay, we attempted to evaluate the effects of these PAHs on the fish aryl hydrocarbon receptor (AHR) signaling pathway. We initially measured PAH concentrations and cytochrome P4501A catalytic activities (EROD: ethoxyresorufin-O-deethylase and MROD: methoxyresorufin-O-demethylase) as markers of AHR activation in greenlings (Hexagrammos otakii) collected from Kesennuma Bay in 2014. The results showed that alkylated PAH concentrations and EROD/MROD activities were higher in sites close to the oil-spilled sites than in the control site, suggesting AHR activation by spilled alkylated PAHs. We then investigated AHR-mediated responses to these PAHs in the in vitro reporter gene assay system where red seabream (Pagrus major) AHR1 (rsAHR1) or rsAHR2 expression plasmids were transiently transfected into COS-7 cells. The in vitro assay showed rsAHR isoform-, PAH-, and dose-dependent transactivation potencies. The relative effective concentrations of benzo[α]pyrene, dibenzothiophene, phenanthrene, 2,3,5-trimethylnaphthalene, acenaphthene, and 1-methylphenanthrene that induce 20% of the maximum benzo[α]pyrene response (REC20-BaP) for rsAHR1 activation were 0.052, 38, 79, 88, 270 nM, and no response, respectively, and those for rsAHR2 activation were 0.0049, 32, 53, 88, 60 nM, and no response, respectively. The results showed that the REC20-BaP values of benzo[α]pyrene for both the rsAHR1 and rsAHR2 isoforms were lower than the concentrations (0.041-0.20 nM) detected in the muscle tissue of fish from Kesennuma Bay, while the REC20-BaP values of other PAHs were higher than their tissue concentrations. In silico rsAHR homology modeling and subsequent ligand docking simulation analyses indicated that the rsAHR activation potencies of PAHs could be predicted from a rsAHR2 model. This study shows that in vitro and in silico rsAHR analyses may be a useful tool for assessing the risks to fish contaminated with PAHs.
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Affiliation(s)
- Su-Min Bak
- Laboratory of Environmental Toxicology, Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matsuyama, 790-8577, Japan.
| | - Haruhiko Nakata
- Faculty of the Advanced Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto, 860-8555, Japan.
| | - Dong-Hee Koh
- Department of Life and Nanopharmaceutical Science, Kyung Hee University,26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea.
| | - Jean Yoo
- Laboratory of Environmental Toxicology, Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matsuyama, 790-8577, Japan.
| | - Hisato Iwata
- Laboratory of Environmental Toxicology, Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matsuyama, 790-8577, Japan.
| | - Eun-Young Kim
- Department of Life and Nanopharmaceutical Science, Kyung Hee University,26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea; Department of Biology, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea.
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8
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Doering JA, Wiseman S, Giesy JP, Hecker M. A Cross-species Quantitative Adverse Outcome Pathway for Activation of the Aryl Hydrocarbon Receptor Leading to Early Life Stage Mortality in Birds and Fishes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:7524-7533. [PMID: 29863850 DOI: 10.1021/acs.est.8b01438] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Dioxin-like compounds (DLCs) elicit adverse effects through activation of the aryl hydrocarbon receptor (AHR). Prior investigations demonstrated that sensitivity to activation of AHR1 in an in vitro AHR transactivation assay is predictive of early life stage mortality among birds. The present study investigated the link between sensitivity to activation of AHR1s and AHR2s and early life stage mortality among fishes. A significant, linear relationship was demonstrated between sensitivity to activation of AHR2 and early life stage mortality among nine fishes, while no relationship was found for AHR1. The slope and y-intercept for the linear relationship between sensitivity to activation of AHR1 and early life stage mortality in birds was not statistically different from the same relationship for AHR2 in fishes. Data for fishes and birds across DLCs were expanded into four significant, linear regression models describing the relationship between sensitivity to activation of AHR and the dose to cause early life stage mortality of 0%, 10%, 50%, or 100%. These four relationships were combined to form a quantitative adverse outcome pathway which can predict dose-response curves of early life stage mortality for DLCs to any bird or fish from species- and chemical-specific responses in an in vitro AHR transactivation assay.
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Affiliation(s)
- Jon A Doering
- Toxicology Centre , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5B3 , Canada
| | - Steve Wiseman
- Toxicology Centre , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5B3 , Canada
- Department of Biological Sciences , University of Lethbridge , Lethbridge , Alberta T1K 3M4 , Canada
| | - John P Giesy
- Toxicology Centre , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5B3 , Canada
- Department of Veterinary Biomedical Sciences , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5B4 , Canada
| | - Markus Hecker
- Toxicology Centre , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5B3 , Canada
- School of Environment and Sustainability , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5C8 , Canada
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9
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Molecular modeling of the AhR structure and interactions can shed light on ligand-dependent activation and transformation mechanisms. CURRENT OPINION IN TOXICOLOGY 2017; 2:42-49. [PMID: 28497129 DOI: 10.1016/j.cotox.2017.01.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Molecular modeling has given important contributions to elucidation of the main stages in the AhR signal transduction pathway. Despite the lack of experimentally determined structures of the AhR functional domains, information derived from homologous systems has been exploited for modeling their structure and interactions. Homology models of the AhR PASB domain have provided information on the binding cavity and contributed to elucidate species-specific differences in ligand binding. Molecular Docking simulations of the ligand binding process have given insights into differences in binding of diverse agonists, antagonists, and selective AhR modulators, and their application to virtual screening of large databases of compounds have allowed identification of novel AhR ligands. Recently available structural information on protein-protein and protein-DNA complexes of other bHLH-PAS systems has opened the way for modeling the AhR:ARNT dimer structure and investigating the mechanisms of AhR transformation and DNA binding. Future research directions should include simulation of the protein dynamics to obtain a more reliable description of intermolecular interactions involved in signal transmission.
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Freeburg SH, Engelbrecht E, Powell WH. Subfunctionalization of Paralogous Aryl Hydrocarbon Receptors from the Frog Xenopus Laevis: Distinct Target Genes and Differential Responses to Specific Agonists in a Single Cell Type. Toxicol Sci 2016; 155:337-347. [PMID: 27994169 DOI: 10.1093/toxsci/kfw212] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Gene duplication confers genetic redundancy that can facilitate subfunctionalization, the partitioning of ancestral functions between paralogs. We capitalize on a recent genome duplication in Xenopus laevis (African clawed frog) to interrogate possible functional differentiation between alloalleles of the aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor that mediates toxicity of dioxin-like compounds and plays a role in the physiology and development of the cardiovascular, hepatic, and immune systems in vertebrates. X. laevis has 2 AHR genes, AHR1α and AHR1β To test the hypothesis that the encoded proteins exhibit different molecular functions, we used TALENs in XLK-WG cells, generating mutant lines lacking functional versions of each AHR and measuring the transcriptional responsiveness of several target genes to the toxic xenobiotic 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and the candidate endogenous ligand 6-formylindolo[3,2-b]carbazole (FICZ). Mutation of either AHR1α or AHR1β reduced TCDD induction of the canonical AHR target, Cytochrome P4501A6, by 75%, despite the much lower abundance of AHR1β in wild-type cells. More modestly induced target genes, encoding aryl hydrocarbon receptor repressor (AHRR), spectrin repeat-containing nuclear envelope protein 1 (SYNE-1), and gap junction protein gamma 1 (GJC1), were regulated solely by AHR1α. AHR1β was responsible for CYP1A6 induction by FICZ, while AHR1α mediated FICZ induction of AHRR We conclude that AHR1α and AHR1β have distinct transcriptional functions in response to specific agonists, even within a single cell type. Functional analysis of frog AHR paralogs advances the understanding of AHR evolution and as well as the use of frog models of developmental toxicology such as FETAX.
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Affiliation(s)
| | | | - Wade H Powell
- Biology Department, Kenyon College, Gambier, Ohio 43022
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