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In-depth analysis of the interactions of various aryl hydrocarbon receptor ligands from a computational perspective. J Mol Graph Model 2023; 118:108339. [PMID: 36183684 DOI: 10.1016/j.jmgm.2022.108339] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 09/01/2022] [Accepted: 09/17/2022] [Indexed: 11/21/2022]
Abstract
Aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that acts as a machinery that controls the expression of many genes, including cytochrome P450 CYP1A1, CYP1A2 and CYP1B1. It plays a principal role in numerous biological and toxicological functions, making it a promising target for developing therapeutic agents. Several novel small molecules targeting the AhR signaling pathway are currently under investigation as antitumor agents. Some have already advanced into clinical trials in patients with various tumors. Activation of AhR by diverse chemicals either endogenous or exogenous is initiated by the binding of these ligands to the PAS-B domain, which modulates AhR functions. There is, however, limited information about how various ligands interact with the PAS-B domain for activating or inhibiting the AhR. To better understand the mode of action of AhR agonists/antagonists. The current work proposes a combination of several computational tools to build dynamical models for the PAS-B domain bound to different ligands in mouse and human. Our findings reveal the essential roles of specific PAS-B residues (e.g., S365, V381& Q383), which mediate the AhR ligand-binding process. Our results also explain how these residues regulate the promiscuity of AhR in accommodating various chemicals in its binding PAS-B ligand-binding pocket.
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2
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An overview of aryl hydrocarbon receptor ligands in the Last two decades (2002–2022): A medicinal chemistry perspective. Eur J Med Chem 2022; 244:114845. [DOI: 10.1016/j.ejmech.2022.114845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 09/28/2022] [Accepted: 10/08/2022] [Indexed: 11/21/2022]
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3
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Molecular and structural basis of interactions of vitamin D3 hydroxyderivatives with aryl hydrocarbon receptor (AhR): An integrated experimental and computational study. Int J Biol Macromol 2022; 209:1111-1123. [PMID: 35421413 DOI: 10.1016/j.ijbiomac.2022.04.048] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 03/10/2022] [Accepted: 04/06/2022] [Indexed: 12/12/2022]
Abstract
To better understand the molecular and structural basis underlying the interaction of vitamin D3 hydroxyderivatives with AhR, molecular simulation was used to probe the binding of 1,20(OH)2D3, 1,25(OH)2D3, 20,23(OH)2D3 and 20(OH)D3 to AhR. qPCR showed that vitamin D3 derivatives stimulate expression of cyp1A1 and cyp1B1 genes that are downstream targets of AhR signaling. These secosteroids stimulated the translocation of the AhR to the nucleus, as measured by flow cytometry and western blotting. Molecular dynamics simulations were used to model the binding of vitamin D3 derivatives to AhR to examine their influence on the structure, conformation and dynamics of the AhR ligand binding domain (LBD). Binding thermodynamics, conformation, secondary structure, dynamical motion and electrostatic potential of AhR were analyzed. The molecular docking scores and binding free energy were all favorable for the binding of D3 derivatives to the AhR. These established ligands and the D3 derivatives are predicted to have different patterns of hydrogen bond formation with the AhR, and varied residue conformational fluctuations and dynamical motion for the LBD. These changes could alter the shape, size and electrostatic potential distribution of the ligand binding pocket, contributing to the different binding affinities of AhR for the natural ligands and D3 derivatives.
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Vazquez-Rivera E, Rojas B, Parrott JC, Shen AL, Xing Y, Carney PR, Bradfield CA. The aryl hydrocarbon receptor as a model PAS sensor. Toxicol Rep 2021; 9:1-11. [PMID: 34950569 PMCID: PMC8671103 DOI: 10.1016/j.toxrep.2021.11.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 11/19/2021] [Accepted: 11/24/2021] [Indexed: 01/02/2023] Open
Abstract
Proteins containing PER-ARNT-SIM (PAS) domains are commonly associated with environmental adaptation in a variety of organisms. The PAS domain is found in proteins throughout Archaea, Bacteria, and Eukarya and often binds small-molecules, supports protein-protein interactions, and transduces input signals to mediate an adaptive physiological response. Signaling events mediated by PAS sensors can occur through induced phosphorelays or genomic events that are often dependent upon PAS domain interactions. In this perspective, we briefly discuss the diversity of PAS domain containing proteins, with particular emphasis on the prototype member, the aryl hydrocarbon receptor (AHR). This ligand-activated transcription factor acts as a sensor of the chemical environment in humans and many chordates. We conclude with the idea that since mammalian PAS proteins often act through PAS-PAS dimers, undocumented interactions of this type may link biological processes that we currently think of as independent. To support this idea, we present a framework to guide future experiments aimed at fully elucidating the spectrum of PAS-PAS interactions with an eye towards understanding how they might influence environmental sensing in human and wildlife populations.
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Affiliation(s)
- Emmanuel Vazquez-Rivera
- Molecular and Environmental Toxicology Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
| | - Brenda Rojas
- Molecular and Environmental Toxicology Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
| | - Jessica C. Parrott
- Molecular and Environmental Toxicology Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
| | - Anna L. Shen
- Molecular and Environmental Toxicology Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
| | - Yongna Xing
- Molecular and Environmental Toxicology Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
| | - Patrick R. Carney
- Molecular and Environmental Toxicology Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
| | - Christopher A. Bradfield
- Molecular and Environmental Toxicology Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
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5
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Long P, Li Y, Wen Q, Huang M, Li S, Lin Y, Huang X, Chen M, Ouyang J, Ao Y, Qi Q, Zhang H, Ye W, Cheng G, Zhang X, Zhang D. 3'-Oxo-tabernaelegantine A (OTNA) selectively relaxes pulmonary arteries by inhibiting AhR. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2021; 92:153751. [PMID: 34563984 DOI: 10.1016/j.phymed.2021.153751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 09/04/2021] [Accepted: 09/12/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Pulmonary arterial hypertension (PAH), characterized by pulmonary artery constriction and vascular remodeling, has a high mortality rate. New drugs for the treatment of PAH urgently need to be developed. PURPOSE This study was designed to investigate the vasorelaxant activity of OTNA in isolated pulmonary arteries, and explore its molecular mechanism. METHODS Pulmonary arteries and thoracic aortas were isolated from mice, and vascular tone was tested with a Wire Myograph System. Nitric oxide levels were determined with DAF-FM DA and DAX-J2™ Red. Cellular thermal shift assays, microscale thermophoresis, and molecular docking were used to identify the interaction between OTNA and aryl hydrocarbon receptor (AhR). The levels of PI3K, p-PI3K, Akt, p-Akt, eNOS, p-eNOS, and AhR were analyzed by Western blotting. RESULTS OTNA selectively relaxed the isolated pulmonary artery rings in an endothelium-dependent manner. Mechanistic study showed that OTNA induced NO production through activation of the PI3K/Akt/eNOS pathway in endothelial cells. Furthermore, we also found that OTNA directly bound to AhR and activated the PI3K/Akt/eNOS pathway to dilate pulmonary arteries by inhibiting AhR. CONCLUSIONS OTNA relaxes pulmonary arteries by antagonizing AhR. This study provides a new natural antagonist of AhR as a promising lead compound for PAH treatment.
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Affiliation(s)
- Pei Long
- College of Pharmacy, Jinan University, Guangzhou 510632, China; Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, Jinan University, Guangzhou 510632, China
| | - Yong Li
- College of Pharmacy, Jinan University, Guangzhou 510632, China; Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, Jinan University, Guangzhou 510632, China; School of Pharmacy, North Sichuan Medical College, Nanchong 637100, China
| | - Qing Wen
- College of Pharmacy, Jinan University, Guangzhou 510632, China; Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, Jinan University, Guangzhou 510632, China
| | - Maohua Huang
- College of Pharmacy, Jinan University, Guangzhou 510632, China; Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, Jinan University, Guangzhou 510632, China
| | - Songtao Li
- College of Pharmacy, Jinan University, Guangzhou 510632, China; Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, Jinan University, Guangzhou 510632, China
| | - Yuning Lin
- College of Pharmacy, Jinan University, Guangzhou 510632, China; Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, Jinan University, Guangzhou 510632, China
| | - Xiaojun Huang
- College of Pharmacy, Jinan University, Guangzhou 510632, China; Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, Jinan University, Guangzhou 510632, China
| | - Minfeng Chen
- College of Pharmacy, Jinan University, Guangzhou 510632, China; Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, Jinan University, Guangzhou 510632, China
| | - Jie Ouyang
- College of Pharmacy, Jinan University, Guangzhou 510632, China; Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, Jinan University, Guangzhou 510632, China
| | - Yunlin Ao
- College of Pharmacy, Jinan University, Guangzhou 510632, China; Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, Jinan University, Guangzhou 510632, China
| | - Qi Qi
- Department of Pharmacology, School of Medicine, Jinan University, Guangzhou 510632, China
| | - Haipeng Zhang
- Department of Pharmacology, School of Medicine, Jinan University, Guangzhou 510632, China
| | - Wencai Ye
- College of Pharmacy, Jinan University, Guangzhou 510632, China; Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, Jinan University, Guangzhou 510632, China
| | - Guohua Cheng
- College of Pharmacy, Jinan University, Guangzhou 510632, China.
| | - Xiaoqi Zhang
- College of Pharmacy, Jinan University, Guangzhou 510632, China; Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, Jinan University, Guangzhou 510632, China.
| | - Dongmei Zhang
- College of Pharmacy, Jinan University, Guangzhou 510632, China; Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, Jinan University, Guangzhou 510632, China.
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6
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Casalegno M, Raos G, Sello G. Identification of viable TCDD access pathways to human AhR PAS-B ligand binding domain. J Mol Graph Model 2021; 105:107886. [PMID: 33706219 DOI: 10.1016/j.jmgm.2021.107886] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 02/06/2021] [Accepted: 02/22/2021] [Indexed: 12/02/2022]
Abstract
Unintentionally released in the environment as by-products of industrial activities, dioxins, exemplified by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), represent a primary concern for human health. Exposure to these chemicals is known to produce a broad spectrum of adverse effects, including cancer. The main mechanism of action of TCDD in humans involves binding to the Aryl hydrocarbon Receptor (AhR). Although qualitatively established, TCDD capture by the AhR remains poorly characterized at the molecular level. Starting from a recently developed structural model of the human AhR PAS-B domain, in this work we attempt the identification of viable TCDD access pathways to the human AhR ligand binding domain by means of molecular dynamics. Based on the result of metadynamics simulations, we identify two main regions that may potentially serve as access paths for TCDD. For each path, we characterize the residues closely interacting with TCDD, thereby suggesting a possible mechanism for TCDD capture. Our results are reviewed and discussed in the light of the available information about Human AhR structure and functions.
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Affiliation(s)
- Mosè Casalegno
- Dipartimento di Chimica, Materiali e Ingegneria Chimica "G. Natta", Politecnico di Milano, Via L. Mancinelli 7, 20131, Milano, Italy.
| | - Guido Raos
- Dipartimento di Chimica, Materiali e Ingegneria Chimica "G. Natta", Politecnico di Milano, Via L. Mancinelli 7, 20131, Milano, Italy.
| | - Guido Sello
- Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, I-20133, Milano, Italy.
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Zhu K, Shen C, Tang C, Zhou Y, He C, Zuo Z. Improvement in the screening performance of potential aryl hydrocarbon receptor ligands by using supervised machine learning. CHEMOSPHERE 2021; 265:129099. [PMID: 33272675 DOI: 10.1016/j.chemosphere.2020.129099] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 11/17/2020] [Accepted: 11/22/2020] [Indexed: 06/12/2023]
Abstract
The aryl hydrocarbon receptor (AhR), which is a ligand-dependent transcription factor, plays a crucial role in the regulation of xenobiotic metabolism. There are a large number of artificial or natural molecules in the environment that can activate AhR. In this study, we developed a virtual screening procedure to identify potential ligands of AhR. One structure-based method and two ligand-based methods were used for the virtual screening procedure. The results showed that the precision rate (0.96) and recall rate (0.64) of our procedure were significantly higher than those of a procedure used in a previous study, which suggests that supervised machine learning techniques can greatly improve the performance of virtual screening. Moreover, a pesticide dataset including 777 frequently used pesticides was screened. Seventy-seven pesticides were identified as potential AhR ligands by all three screening methods, among which 12 have never been previously reported as AhR agonists. Two non-agonist AhR ligands and 14 of the 77 pesticides were randomly selected for testing by in vitro and in vivo assays. All 14 pesticides showed different degrees of AhR agonistic activity, and none of the two non-agonist AhR ligand pesticides showed AhR agonistic activity, which suggests that our procedure had good robustness. Four of the pesticides were reported as AhR agonists for the first time, suggesting that these pesticides may need further toxicity assessment. In general, our procedure is a rapid, powerful and computationally inexpensive tool for predicting chemicals with AhR agonistic activity, which could be useful for environmental risk prediction and management.
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Affiliation(s)
- Kongyang Zhu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - Chao Shen
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - Chen Tang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - Yixi Zhou
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - Chengyong He
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China.
| | - Zhenghong Zuo
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, 361005, China.
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8
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Gu C, Cai J, Fan X, Bian Y, Yang X, Xia Q, Sun C, Jiang X. Theoretical investigation of AhR binding property with relevant structural requirements for AhR-mediated toxicity of polybrominated diphenyl ethers. CHEMOSPHERE 2020; 249:126554. [PMID: 32213394 DOI: 10.1016/j.chemosphere.2020.126554] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 03/16/2020] [Accepted: 03/17/2020] [Indexed: 06/10/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs) are more frequently suspected with the induction of toxicity via signal transduction pathway of cytosolic aryl hydrocarbon receptor (AhR), the initial binding to which is assumed to be an essential prerequisite during the ligand-dependent activation. However, the AhR binding property and associated toxicity of PBDEs is yet to be clearly known for lacking insights into the structural requirements at molecular level. To understand the AhR binding property of PBDEs, the ligand binding domain (LBD) of AhR was simulatively developed on homologous protein after basic validation of geometrical rationality and the binding interaction profile was visually described using molecular docking approach. For AhR binding, the offset or edge-on π-π stackings with aromatic motifs including Phe289, Phe345 and His285 were shown to be structurally required whereas the electrostatic attraction validated for AhR binding to dioxins might be less effective for 2,2',3,4,4'-pentabromodiphenyl ether (BDE-85). Besides the demands of less steric hindrance from alanines and weak formulation of hydrogen bonds, the dispersion force through large contact and polarization of S-π electrons seemed to be impactful when BDE-85 were closer to Cys327, Met334 or Met342. With theoretical computation of AhR binding energies, the more significant correlativity with bioassays was derived especially for the lowly/moderately brominated congeners, and could be used to predict the AhR binding affinity on certain degree. The informative results would thus not only help well understand the molecular basis of AhR-mediated toxicity but give an approach for accelerative evaluation of AhR binding and toxicity of PBDEs.
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Affiliation(s)
- Chenggang Gu
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, PR China.
| | - Jun Cai
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, PR China; University of the Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Xiuli Fan
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, PR China; University of the Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Yongrong Bian
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, PR China
| | - Xinglun Yang
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, PR China
| | - Qiying Xia
- Shandong Province Key Laboratory of Soil Conservation and Environmental Protection, Linyi University, Linyi, 276005, PR China.
| | - Cheng Sun
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing, 210023, PR China
| | - Xin Jiang
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, PR China.
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9
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Artyukov AA, Zelepuga EA, Bogdanovich LN, Lupach NM, Novikov VL, Rutckova TA, Kozlovskaya EP. Marine Polyhydroxynaphthoquinone, Echinochrome A: Prevention of Atherosclerotic Inflammation and Probable Molecular Targets. J Clin Med 2020; 9:E1494. [PMID: 32429179 PMCID: PMC7291202 DOI: 10.3390/jcm9051494] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 05/06/2020] [Accepted: 05/13/2020] [Indexed: 12/16/2022] Open
Abstract
The effect of low doses of echinochrome A (EchA), a natural polyhydroxy-1,4-naphthoquinone pigment from the sea urchin Scaphechinus mirabilis, has been studied in clinical trials, when it was used as an active substance of the drug Histochrome® and biologically active supplement Thymarin. Several parameters of lipid metabolism, antioxidant status, and the state of the immune system were analyzed in patients with cardiovascular diseases (CVD), including contaminating atherosclerosis. It has been shown that EchA effectively normalizes lipid metabolism, recovers antioxidant status and reduces atherosclerotic inflammation, regardless of the method of these preparations' administrations. Treatment of EchA has led to the stabilization of patients, improved function of the intracellular matrix and decreased epithelial dysfunction. The increased expression of surface human leukocyte antigen DR isotype (HLA-DR) receptors reflects the intensification of intercellular cooperation of immune cells, as well as an increase in the efficiency of processing and presentation of antigens, while the regulation of CD95 + expression levels suggests the stimulation of cell renewal processes. The immune system goes to a different level of functioning. Computer simulations suggest that EchA, with its aromatic structure of the naphthoquinone nucleus, may be a suitable ligand of the cytosolic aryl cell receptor, which affects the response of the immune system and causes the rapid expression of detoxification enzymes such as CYP and DT diaphorase, which play a protective role with CVD. Therefore, EchA possesses not only an antiradical effect and antioxidant activity, but is also a SOD3 mimetic, producing hydrogen peroxide and controlling the expression of cell enzymes through hypoxia-inducible factors (HIF), peroxisome proliferator-activated receptors (PPARs) and aryl hydrocarbon receptor (AhR).
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Affiliation(s)
- Aleksandr A. Artyukov
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Science, 159 Prospect 100-letiya Vladivostoka, Vladivostok 690022, Russia; (A.A.A.); (E.A.Z.); (V.L.N.); (T.A.R.)
| | - Elena A. Zelepuga
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Science, 159 Prospect 100-letiya Vladivostoka, Vladivostok 690022, Russia; (A.A.A.); (E.A.Z.); (V.L.N.); (T.A.R.)
| | - Larisa N. Bogdanovich
- Medical Association of the Far Eastern Branch of the Russian Academy of Sciences (FEB RAS MO), Kirov Str., 95, Vladivostok 690022, Russia;
| | - Natalia M. Lupach
- Primorye Regional Clinical Hospital No. One (SHI), Aleutskaya Str., 57, Vladivostok, Primorsky Krai 690091, Russia;
| | - Vyacheslav L. Novikov
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Science, 159 Prospect 100-letiya Vladivostoka, Vladivostok 690022, Russia; (A.A.A.); (E.A.Z.); (V.L.N.); (T.A.R.)
| | - Tatyana A. Rutckova
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Science, 159 Prospect 100-letiya Vladivostoka, Vladivostok 690022, Russia; (A.A.A.); (E.A.Z.); (V.L.N.); (T.A.R.)
| | - Emma P. Kozlovskaya
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Science, 159 Prospect 100-letiya Vladivostoka, Vladivostok 690022, Russia; (A.A.A.); (E.A.Z.); (V.L.N.); (T.A.R.)
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10
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Avilla MN, Malecki KMC, Hahn ME, Wilson RH, Bradfield CA. The Ah Receptor: Adaptive Metabolism, Ligand Diversity, and the Xenokine Model. Chem Res Toxicol 2020; 33:860-879. [PMID: 32259433 PMCID: PMC7175458 DOI: 10.1021/acs.chemrestox.9b00476] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Indexed: 12/12/2022]
Abstract
The Ah receptor (AHR) has been studied for almost five decades. Yet, we still have many important questions about its role in normal physiology and development. Moreover, we still do not fully understand how this protein mediates the adverse effects of a variety of environmental pollutants, such as the polycyclic aromatic hydrocarbons (PAHs), the chlorinated dibenzo-p-dioxins ("dioxins"), and many polyhalogenated biphenyls. To provide a platform for future research, we provide the historical underpinnings of our current state of knowledge about AHR signal transduction, identify a few areas of needed research, and then develop concepts such as adaptive metabolism, ligand structural diversity, and the importance of proligands in receptor activation. We finish with a discussion of the cognate physiological role of the AHR, our perspective on why this receptor is so highly conserved, and how we might think about its cognate ligands in the future.
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Affiliation(s)
- Mele N. Avilla
- Molecular and Environmental Toxicology
Center, Department of Population Health
Sciences, University of Wisconsin School
of Medicine and Public Health, Madison, Wisconsin 53726-2379, United States
| | - Kristen M. C. Malecki
- Molecular and Environmental Toxicology
Center, Department of Population Health
Sciences, University of Wisconsin School
of Medicine and Public Health, Madison, Wisconsin 53726-2379, United States
| | - Mark E. Hahn
- Biology
Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543-1050, United States
| | - Rachel H. Wilson
- Molecular and Environmental Toxicology
Center, Department of Population Health
Sciences, University of Wisconsin School
of Medicine and Public Health, Madison, Wisconsin 53726-2379, United States
| | - Christopher A. Bradfield
- Molecular and Environmental Toxicology
Center, Department of Population Health
Sciences, University of Wisconsin School
of Medicine and Public Health, Madison, Wisconsin 53726-2379, United States
- McArdle
Laboratory for Cancer Research, University of Wisconsin School of Medicine
and Public Health, Madison, Wisconsin 53705-227, United States
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11
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Calahorra J, Martínez-Lara E, Granadino-Roldán JM, Martí JM, Cañuelo A, Blanco S, Oliver FJ, Siles E. Crosstalk between hydroxytyrosol, a major olive oil phenol, and HIF-1 in MCF-7 breast cancer cells. Sci Rep 2020; 10:6361. [PMID: 32286485 PMCID: PMC7156391 DOI: 10.1038/s41598-020-63417-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 03/30/2020] [Indexed: 12/14/2022] Open
Abstract
Olive oil intake has been linked with a lower incidence of breast cancer. Hypoxic microenvironment in solid tumors, such as breast cancer, is known to play a crucial role in cancer progression and in the failure of anticancer treatments. HIF-1 is the foremost effector in hypoxic response, and given that hydroxytyrosol (HT) is one of the main bioactive compounds in olive oil, in this study we deepen into its modulatory role on HIF-1. Our results in MCF-7 breast cancer cells demonstrate that HT decreases HIF-1α protein, probably by downregulating oxidative stress and by inhibiting the PI3K/Akt/mTOR pathway. Strikingly, the expression of HIF-1 target genes does not show a parallel decrease. Particularly, adrenomedullin and vascular endothelial growth factor are up-regulated by high concentrations of HT even in HIF-1α silenced cells, pointing to HIF-1-independent mechanisms of regulation. In fact, we show, by in silico modelling and transcriptional analysis, that high doses of HT may act as an agonist of the aryl hydrocarbon receptor favoring the induction of these angiogenic genes. In conclusion, we suggest that the effect of HT in a hypoxic environment is largely affected by its concentration and involves both HIF-1 dependent and independent mechanisms.
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Affiliation(s)
- Jesús Calahorra
- Departamento de Biología Experimental, Universidad de Jaén, Campus Las Lagunillas s/n, Jaén, 23071, Spain
| | - Esther Martínez-Lara
- Departamento de Biología Experimental, Universidad de Jaén, Campus Las Lagunillas s/n, Jaén, 23071, Spain
| | - José M Granadino-Roldán
- Departamento de Química Física y Analítica, Universidad de Jaén, Campus Las Lagunillas s/n, Jaén, 23071, Spain
| | - Juan M Martí
- Instituto López Neyra de Parasitología y Biomedicina, IPBLN, CSIC PTS-Granada, Armilla, 18016, Spain
| | - Ana Cañuelo
- Departamento de Biología Experimental, Universidad de Jaén, Campus Las Lagunillas s/n, Jaén, 23071, Spain
| | - Santos Blanco
- Departamento de Biología Experimental, Universidad de Jaén, Campus Las Lagunillas s/n, Jaén, 23071, Spain
| | - F Javier Oliver
- Instituto López Neyra de Parasitología y Biomedicina, IPBLN, CSIC PTS-Granada, Armilla, 18016, Spain
| | - Eva Siles
- Departamento de Biología Experimental, Universidad de Jaén, Campus Las Lagunillas s/n, Jaén, 23071, Spain.
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12
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Dolciami D, Ballarotto M, Gargaro M, López-Cara LC, Fallarino F, Macchiarulo A. Targeting Aryl hydrocarbon receptor for next-generation immunotherapies: Selective modulators (SAhRMs) versus rapidly metabolized ligands (RMAhRLs). Eur J Med Chem 2019; 185:111842. [PMID: 31727470 DOI: 10.1016/j.ejmech.2019.111842] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 10/30/2019] [Accepted: 10/30/2019] [Indexed: 12/12/2022]
Abstract
Aryl Hydrocarbon Receptor (AhR) constitutes a major network hub of genomic and non-genomic signaling pathways, connecting host's immune cells to environmental factors. It shapes innate and adaptive immune processes to environmental stimuli with species-, cell- and tissue-type dependent specificity. Although an ever increasing number of studies has thrust AhR into the limelight as attractive target for the development of next-generation immunotherapies, concerns exist on potential safety issues associated with small molecule modulation of the receptor. Selective AhR modulators (SAhRMs) and rapidly metabolized AhR ligands (RMAhRLs) are two classes of receptor agonists that are emerging as interesting lead compounds to bypass AhR-related toxicity in favor of therapeutic effects. In this article, we discuss SAhRMs and RMAhRLs reported in literature, covering concepts underlying their definitions, specific binding modes, structure-activity relationships and AhR-mediated functions.
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Affiliation(s)
- Daniela Dolciami
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo, 1, 06123, Perugia, Italy
| | - Marco Ballarotto
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo, 1, 06123, Perugia, Italy
| | - Marco Gargaro
- Department of Experimental Medicine, University of Perugia, Piazz.le Gambuli, 1, 06132, Perugia, Italy
| | - Luisa Carlota López-Cara
- Department of Pharmaceutical & Organic Chemistry, Faculty of Pharmacy, University of Granada, 18010, Granada, Spain
| | - Francesca Fallarino
- Department of Experimental Medicine, University of Perugia, Piazz.le Gambuli, 1, 06132, Perugia, Italy
| | - Antonio Macchiarulo
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo, 1, 06123, Perugia, Italy.
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13
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Pan Y, Peng T, Xu P, Zeng X, Tian F, Song J, Shang Q. Transcription Factors AhR/ARNT Regulate the Expression of CYP6CY3 and CYP6CY4 Switch Conferring Nicotine Adaptation. Int J Mol Sci 2019; 20:E4521. [PMID: 31547315 PMCID: PMC6770377 DOI: 10.3390/ijms20184521] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 09/08/2019] [Accepted: 09/08/2019] [Indexed: 02/06/2023] Open
Abstract
Nicotine is one of the most toxic secondary plant metabolites in nature and it is highly toxic to herbivorous insects. The overexpression of CYP6CY3 and its homologous isozyme CYP6CY4 in Myzus persicae nicotianae is correlated with nicotine tolerance. The expanded (AC)n repeat in promoter is the cis element for CYP6CY3 transcription. These repeat sequences are conserved in the CYP6CY3 gene from Aphis gossypii and the homologous P450 genes in Acyrthosiphon pisum. The potential transcriptional factors that may regulate CYP6CY3 were isolated by DNA pulldown and sequenced in order to investigate the underlying transcriptional regulation mechanism of CYP6CY3. These identified transcriptional factors, AhR and ARNT, whose abundance was highly correlated with an abundance of the CYP6CY3 gene, were validated. RNAi and co-transfection results further confirm that AhR and ARNT play a major role in the transcriptional regulation of the CYP6CY3 gene. When the CYP6CY3 transcript is destabilized by AhR/ARNT RNAi, the transcription of the CYP6CY4 is dramatically up-regulated, indicating a compensatory mechanism between the CYP6CY3 and CYP6CY4 genes. Our present study sheds light on the CYP6CY3 and CYP6CY4 mediated nicotine adaption of M. persicae nicotianae to tobacco. The current studies shed light on the molecular mechanisms that underlie the genotypic and phenotypic changes that are involved in insect host shifts and we conclude that AhR/ARNT regulate the expression of CYP6CY3 and CYP6CY4 cooperatively, conferring the nicotine adaption of M. persicae nicotianae to tobacco.
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Affiliation(s)
- Yiou Pan
- School of Agricultural Science, Zhengzhou University, Zhengzhou 450001, China
- College of Plant Science, Jilin University, Changchun 130062, China
| | - Tianfei Peng
- College of Plant Science, Jilin University, Changchun 130062, China
| | - Pengjun Xu
- Institute of Tobacco Research, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
| | - Xiaochun Zeng
- College of Plant Science, Jilin University, Changchun 130062, China
| | - Fayi Tian
- College of Plant Science, Jilin University, Changchun 130062, China
| | - Jiabao Song
- College of Plant Science, Jilin University, Changchun 130062, China
| | - Qingli Shang
- School of Agricultural Science, Zhengzhou University, Zhengzhou 450001, China.
- College of Plant Science, Jilin University, Changchun 130062, China.
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14
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Zhou Y, Li S, Huang L, Yang Y, Zhang L, Yang M, Liu W, Ramasamy K, Jiang Z, Sundaresan P, Zhu X, Yang Z. A splicing mutation in aryl hydrocarbon receptor associated with retinitis pigmentosa. Hum Mol Genet 2019; 27:2563-2572. [PMID: 29726989 DOI: 10.1093/hmg/ddy165] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 04/30/2018] [Indexed: 12/14/2022] Open
Abstract
Retinitis pigmentosa (RP) refers to a group of retinal degenerative diseases, which often lead to vision loss. Although 70 genes have been identified in RP patients, the genetic cause of approximately 30% of RP cases remains unknown. We aimed to identify the cause of the disease in a cohort of RP families by whole exome sequencing. A rare homozygous splicing variant, c.1160 + 1G>A, which introduced skipping of exon 9 of the aryl hydrocarbon receptor (AHR), was identified in family RD-134. This variant is very rare in several exome databases and leads to skipping of exon 9 in the transcript. AHR is expressed in the human retina and is a ligand-activated transcription factor with multiple functions. Mutant AHR failed to promote 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD)-induced xenobiotic responsive element (XRE) luciferase activity. In parallel, mutation in AHR abolished activation of its downstream target gene, such as CYP1A1 and CYP1A2. To investigate the in vivo roles of Ahr in the retina, we generated a retina-specific conditional knockout mouse model of Ahr. Comparing with wild-type mouse, Ahr knockout mice exhibited reduced electroretinogram responses at 9 months of age. Retinal histology revealed retinal histology showed the degeneration of photoreceptors with a thinner outer nuclear layer. Thus, our data demonstrate that AHR is associated with RP.
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Affiliation(s)
- Yu Zhou
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
| | - Shujin Li
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,Chengdu Institute of Biology, Sichuan Translational Medicine Research Hospital, Chinese Academy of Sciences, Chengdu, Sichuan, China
| | - Lulin Huang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
| | - Yeming Yang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
| | - Lin Zhang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
| | - Mu Yang
- Chengdu Institute of Biology, Sichuan Translational Medicine Research Hospital, Chinese Academy of Sciences, Chengdu, Sichuan, China
| | - Wenjing Liu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Kim Ramasamy
- Retina-Vitreous Services, Aravind Eye Hospital, Madurai, Tamil Nadu, India
| | - Zhilin Jiang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
| | - Periasamy Sundaresan
- Department of Genetics, Aravind Medical Research Foundation, Aravind Eye Hospital, Madurai, Tamil Nadu, India
| | - Xianjun Zhu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,Chengdu Institute of Biology, Sichuan Translational Medicine Research Hospital, Chinese Academy of Sciences, Chengdu, Sichuan, China.,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China.,Institute of Laboratory Animal Sciences, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
| | - Zhenglin Yang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,Chengdu Institute of Biology, Sichuan Translational Medicine Research Hospital, Chinese Academy of Sciences, Chengdu, Sichuan, China.,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
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15
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Tkachenko A, Bermudez M, Irmer-Stooff S, Genkinger D, Henkler-Stephani F, Wolber G, Luch A. Nuclear transport of the human aryl hydrocarbon receptor and subsequent gene induction relies on its residue histidine 291. Arch Toxicol 2017; 92:1151-1160. [PMID: 29164305 DOI: 10.1007/s00204-017-2129-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 11/15/2017] [Indexed: 12/11/2022]
Abstract
The aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor involved in the metabolism of physiological substances and xenobiotics, representing an interesting target in both toxicology and pharmacology. In this study, we investigated the ligand-dependent conjunction of nuclear import of the human AHR in living cells and target gene induction. Our findings strengthen the theory that the AHR triggers a precisely defined and rapid reaction upon binding to endogenous ligands, while the xenobiotic β-naphthoflavone only induces rather unspecific and slow effects. To better illuminate the ligand-mediated responses of the human AHR, we applied site-directed mutagenesis and identified histidine 291 as key residue for AHR functionality, essential for both nuclear import and target gene induction. Contrary, replacing histidine at position 291 by alanine did not affect nucleo-cytoplasmic shuttling, showing that permanent endogenous import and ligand-induced import of the AHR into the nucleus are two independent and differently regulated processes. Combining these observations with our structural investigations using a homology model of the AHR-PAS B domain, we suggest a dual role of histidine 291: (1) a major role for shaping the ligand binding site including direct interactions with ligands and, (2) an essential role for the conformational dynamics of a PAS B loop, which most likely influences the association of the AHR with the AHR nuclear translocator through interference with their protein-protein interface.
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Affiliation(s)
- A Tkachenko
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Strasse 8-10, 10589, Berlin, Germany.
| | - M Bermudez
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Straße 2 + 4, 14195, Berlin, Germany
| | - S Irmer-Stooff
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Strasse 8-10, 10589, Berlin, Germany
| | - D Genkinger
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Strasse 8-10, 10589, Berlin, Germany
| | - F Henkler-Stephani
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Strasse 8-10, 10589, Berlin, Germany
| | - G Wolber
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Straße 2 + 4, 14195, Berlin, Germany
| | - A Luch
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Strasse 8-10, 10589, Berlin, Germany
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16
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Peng T, Chen X, Pan Y, Zheng Z, Wei X, Xi J, Zhang J, Gao X, Shang Q. Transcription factor aryl hydrocarbon receptor/aryl hydrocarbon receptor nuclear translocator is involved in regulation of the xenobiotic tolerance-related cytochrome P450 CYP6DA2 in Aphis gossypii Glover. INSECT MOLECULAR BIOLOGY 2017; 26:485-495. [PMID: 28463435 DOI: 10.1111/imb.12311] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The cotton aphid, Aphis gossypii, is one of the most economically important agricultural pests worldwide as it is polyphagous and resistant to many classes of insecticides. Overexpression of the cytochrome P450 monooxygenase (P450) CYP6DA2 has previously been found to be associated with gossypol and spirotetramat tolerance in the cotton aphid. In the present study, the elements located in the promoter region (-357:-343; -250:-241; -113:-104) of CYP6DA2 were shown to control promoter activity, and gossypol induction was observed. We hypothesized that the expression of CYP6DA2 is subject to transcriptional regulation. To investigate the underlying mechanism, we assessed two transcription factors, aryl hydrocarbon receptor (AhR) and aryl hydrocarbon receptor nuclear translocator (ARNT), and found that the abundance of AhR was highly correlated with CYP6DA2 abundance. RNA interference of AhR or ARNT significantly decreased the levels of the target gene as well as those of its counterpart, and both dramatically repressed CYP6DA2 expression. Cotransfection of the ARNT, AhR, or AhR plus ARNT and CYP6DA2 promoter constructs elevated CYP6DA2 promoter activity, with the AhR plus ARNT cotransfection being the most effective. Thus, these elements located in the promoter were responsible for CYP6DA2 transcription, and CYP6DA2 expression was regulated by the transcription factors AhR and ARNT.
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Affiliation(s)
- T Peng
- College of Plant Science, Jilin University, Changchun, China
| | - X Chen
- Department of Entomology, China Agricultural University, Beijing, China
| | - Y Pan
- College of Plant Science, Jilin University, Changchun, China
| | - Z Zheng
- College of Plant Science, Jilin University, Changchun, China
| | - X Wei
- College of Plant Science, Jilin University, Changchun, China
| | - J Xi
- College of Plant Science, Jilin University, Changchun, China
| | - J Zhang
- College of Plant Science, Jilin University, Changchun, China
| | - X Gao
- Department of Entomology, China Agricultural University, Beijing, China
| | - Q Shang
- College of Plant Science, Jilin University, Changchun, China
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17
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Orlowska K, Molcan T, Swigonska S, Sadowska A, Jablonska M, Nynca A, Jastrzebski JP, Ciereszko RE. The tertiary structures of porcine AhR and ARNT proteins and molecular interactions within the TCDD/AhR/ARNT complex. J Mol Graph Model 2016; 67:119-26. [PMID: 27288759 DOI: 10.1016/j.jmgm.2016.05.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 05/24/2016] [Accepted: 05/25/2016] [Indexed: 01/05/2023]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that can be activated by structurally diverse synthetic and natural chemicals, including toxic environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In the present study, homology models of the porcine AhR-ligand binding domain (LBD) and the porcine aryl hydrocarbon receptor nuclear translocator-ligand binding domain (ARNT-LBD) were created on the basis of structures of closely related respective proteins i.e., human Hif-2α and ARNT. Molecular docking of TCDD to the porcine AhR-LBD model revealed high binding affinity (-8.8kcal/mol) between TCDD and the receptor. Moreover, formation of the TCDD/AhR-LBD complex was confirmed experimentally with the use of electrophoretic mobility shift assay (EMSA). It was found that TCDD (10nM, 2h of incubation) not only bound to the AhR in the porcine granulosa cells but also activated the receptor. The current study provides a framework for examining the key events involved in the ligand-dependent activation of the AhR.
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Affiliation(s)
- Karina Orlowska
- Department of Animal Physiology, University of Warmia and Mazury, Olsztyn, Poland
| | - Tomasz Molcan
- Department of Animal Physiology, University of Warmia and Mazury, Olsztyn, Poland
| | - Sylwia Swigonska
- Laboratory of Molecular Diagnostics, University of Warmia and Mazury, Olsztyn, Poland
| | - Agnieszka Sadowska
- Department of Animal Physiology, University of Warmia and Mazury, Olsztyn, Poland
| | - Monika Jablonska
- Department of Animal Physiology, University of Warmia and Mazury, Olsztyn, Poland
| | - Anna Nynca
- Laboratory of Molecular Diagnostics, University of Warmia and Mazury, Olsztyn, Poland
| | - Jan P Jastrzebski
- Department of Plant Physiology, Genetics and Biotechnology, University of Warmia and Mazury, Olsztyn, Poland
| | - Renata E Ciereszko
- Department of Animal Physiology, University of Warmia and Mazury, Olsztyn, Poland; Laboratory of Molecular Diagnostics, University of Warmia and Mazury, Olsztyn, Poland.
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18
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Jin HL, Jeong KW. Regulation of aryl hydrocarbon receptor-mediated transcription in human retinal pigmented epithelial cells. Biochem Biophys Res Commun 2016; 472:366-72. [PMID: 26966070 DOI: 10.1016/j.bbrc.2016.03.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 03/04/2016] [Indexed: 01/07/2023]
Abstract
The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor with pleiotropic effects in normal physiology or vascular development, xenobiotic metabolism, and cancer. A previous study has reported that BRG1, a component of the SWI/SNF complex, is a coactivator for AHR and is recruited to the promoter region of the CYP1A1 gene in mouse hepatocytes. Recent data suggest that AHR is also expressed in human retinal pigment epithelial cells (ARPE-19), which play a crucial role in retinal physiology and the visual cycle. Multiple studies have shown that the AHR plays an important role in the pathogenesis of retinal diseases including age-related macular degeneration. However, the mechanism of AHR transcriptional activation in retinal pigment cells has not been reported. Here, we demonstrate that the AHR signaling pathway is active in ARPE-19 cells, as in hepatocytes, but with different target gene specificity. We also found that chromatin remodeling by the BRG1-containing SWI/SNF complex is required for the AHR-mediated expression of target genes in ARPE-19 cells. We identified a novel enhancer region (-12 kb) of the CYP1A1 gene in ARPE-19 cells, to which both AHR and BRG1 are recruited in a ligand-dependent manner. BRG1 is associated with the AHR in ARPE-19 cells, and the C-terminal activation domain of the AHR directly interacts with BRG1. Furthermore, depletion of BRG1 caused a reduction in chromatin accessibility at the CYP1A1 enhancer. These results suggest that ARPE-19 cells possess an AHR-mediated transcription pathway with different target gene specificity, and that BRG1 is required for AHR-mediated transcription in ARPE-19 cells.
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Affiliation(s)
- Hong Lan Jin
- Gachon Institute of Pharmaceutical Sciences, College of Pharmacy, Gachon University, 191 Hambakmoero, Yeonsu-gu, Incheon 406-799, Republic of Korea
| | - Kwang Won Jeong
- Gachon Institute of Pharmaceutical Sciences, College of Pharmacy, Gachon University, 191 Hambakmoero, Yeonsu-gu, Incheon 406-799, Republic of Korea.
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19
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Mackowiak B, Wang H. Mechanisms of xenobiotic receptor activation: Direct vs. indirect. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:1130-1140. [PMID: 26877237 DOI: 10.1016/j.bbagrm.2016.02.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 02/05/2016] [Accepted: 02/06/2016] [Indexed: 12/31/2022]
Abstract
The so-called xenobiotic receptors (XRs) have functionally evolved into cellular sensors for both endogenous and exogenous stimuli by regulating the transcription of genes encoding drug-metabolizing enzymes and transporters, as well as those involving energy homeostasis, cell proliferation, and/or immune responses. Unlike prototypical steroid hormone receptors, XRs are activated through both direct ligand-binding and ligand-independent (indirect) mechanisms by a plethora of structurally unrelated chemicals. This review covers research literature that discusses direct vs. indirect activation of XRs. A particular focus is centered on the signaling control of the constitutive androstane receptor (CAR), the pregnane X receptor (PXR), and the aryl hydrocarbon receptor (AhR). We expect that this review will shed light on both the common and distinct mechanisms associated with activation of these three XRs. This article is part of a Special Issue entitled: Xenobiotic nuclear receptors: New Tricks for An Old Dog, edited by Dr. Wen Xie.
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Affiliation(s)
- Bryan Mackowiak
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, 20 Penn Street, Baltimore, MD 21201, United States
| | - Hongbing Wang
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, 20 Penn Street, Baltimore, MD 21201, United States.
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20
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Tian W, Pei X, Xie HQ, Xu SL, Tian J, Hu Q, Xu H, Chen Y, Fu H, Cao Z, Zhao B. Development and characterization of monoclonal antibodies against human aryl hydrocarbon receptor. J Environ Sci (China) 2016; 39:165-174. [PMID: 26899655 DOI: 10.1016/j.jes.2015.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 11/09/2015] [Accepted: 11/16/2015] [Indexed: 06/05/2023]
Abstract
Aryl hydrocarbon receptor (AhR), a ligand-dependent nuclear receptor, is involved in a diverse spectrum of biological and toxicological effects. Due to the lack of three dimensional (3D) crystal or nuclear magnetic resonance structure, the mechanisms of these complex effects of AhR remain to be unclear. Also, commercial monoclonal antibodies (mAbs) against human AhR protein (hAhR), as alternative immunological tools, are very limited. Thus, in order to provide more tools for further studies on hAhR, we prepared two mAbs (1D6 and 4A6) against hAhR. The two newly generated mAbs specifically bound to amino acids 484-508 (located in transcription activation domain) and amino acids 201-215 (located in Per-ARNT-Sim domain) of hAhR, respectively. These epitopes were new as compared with those of commercial mAbs. The mAbs were also characterized by enzyme-linked immunosorbent assay, western blot, immunoprecipitation and indirect immunofluorescence assay in different cell lines. The results showed that the two mAbs could recognize the linearized AhRs in six different human cell lines and a rat hepatoma cell line, as well as the hAhR with native conformations. We concluded that the newly generated mAbs could be employed in AhR-based bioassays for analysis of environmental contaminants, and held great potential for further revealing the spatial structure of AhR and its biological functions in future studies.
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Affiliation(s)
- Wenjing Tian
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Xinhui Pei
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Heidi Qunhui Xie
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
| | - Sherry Li Xu
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Jijing Tian
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Qin Hu
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Haiming Xu
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yangsheng Chen
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Hualing Fu
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Zhengyu Cao
- China Pharmaceutical University, Nanjing 211198, China.
| | - Bin Zhao
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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21
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Lee S, Shin WH, Hong S, Kang H, Jung D, Yim UH, Shim WJ, Khim JS, Seok C, Giesy JP, Choi K. Measured and predicted affinities of binding and relative potencies to activate the AhR of PAHs and their alkylated analogues. CHEMOSPHERE 2015; 139:23-29. [PMID: 26037956 DOI: 10.1016/j.chemosphere.2015.05.033] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 04/16/2015] [Accepted: 05/11/2015] [Indexed: 06/04/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) and their alkylated forms are important components of crude oil. Both groups of PAHs have been reported to cause dioxin-like responses, mediated by aryl hydrocarbon receptor (AhR). Thus, characterization of binding affinity to the AhR of unsubstituted or alkylated PAHs is important to understand the toxicological consequences of oil contamination on ecosystems. We investigated the potencies of major PAHs of crude oil, e.g., chrysene, phenanthrene and dibenzothiophene, and their alkylated forms (n=17) to upregulate expression of AhR-mediated processes by use of the H4IIE-luc transactivation bioassay. In addition, molecular descriptors of different AhR activation potencies among PAHs were investigated by use of computational molecular docking models. Based on responses of the H4IIE-luc in vitro assay, it was shown that potencies of PAHs were determined by alkylation in addition to the number and conformation of rings. Potencies of AhR-mediated processes were generally greater when a chrysene group was substituted, especially in 1-methyl-chrysene. Significant negative correlations were observed between the in vitro dioxin-like potency measured in H4IIE-luc cells and the binding distance estimated from the in silico modeling. The difference in relative potency for AhR activation observed among PAHs and their alkylated forms could be explained by differences among binding distances in the ligand binding domain of the AhR caused by alkylation. The docking model developed in the present study may have utility in predicting risks of environmental contaminants of which toxicities are mediated by AhR binding.
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Affiliation(s)
- Sangwoo Lee
- School of Public Health, Seoul National University, Seoul, South Korea
| | - Woong-Hee Shin
- Department of Chemistry, Seoul National University, Seoul, South Korea
| | - Seongjin Hong
- School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul, South Korea
| | - Habyeong Kang
- School of Public Health, Seoul National University, Seoul, South Korea
| | - Dawoon Jung
- School of Public Health, Seoul National University, Seoul, South Korea
| | - Un Hyuk Yim
- Oil and POPs Research Group, Korea Institute of Ocean Science and Technology (KIOST), Geoje, South Korea
| | - Won Joon Shim
- Oil and POPs Research Group, Korea Institute of Ocean Science and Technology (KIOST), Geoje, South Korea
| | - Jong Seong Khim
- School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul, South Korea
| | - Chaok Seok
- Department of Chemistry, Seoul National University, Seoul, South Korea
| | - John P Giesy
- Department of Veterinary Biomedical Sciences and Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada; Department of Zoology, and Center for Integrative Toxicology, Michigan State University, East Lansing, MI, USA; Department of Biology & Chemistry and State Key Laboratory in Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region
| | - Kyungho Choi
- School of Public Health, Seoul National University, Seoul, South Korea.
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22
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Esser C, Rannug A. The aryl hydrocarbon receptor in barrier organ physiology, immunology, and toxicology. Pharmacol Rev 2015; 67:259-79. [PMID: 25657351 DOI: 10.1124/pr.114.009001] [Citation(s) in RCA: 351] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The aryl hydrocarbon receptor (AhR) is an evolutionarily old transcription factor belonging to the Per-ARNT-Sim-basic helix-loop-helix protein family. AhR translocates into the nucleus upon binding of various small molecules into the pocket of its single-ligand binding domain. AhR binding to both xenobiotic and endogenous ligands results in highly cell-specific transcriptome changes and in changes in cellular functions. We discuss here the role of AhR for immune cells of the barrier organs: skin, gut, and lung. Both adaptive and innate immune cells require AhR signaling at critical checkpoints. We also discuss the current two prevailing views-namely, 1) AhR as a promiscuous sensor for small chemicals and 2) a role for AhR as a balancing factor for cell differentiation and function, which is controlled by levels of endogenous high-affinity ligands. AhR signaling is considered a promising drug and preventive target, particularly for cancer, inflammatory, and autoimmune diseases. Therefore, understanding its biology is of great importance.
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Affiliation(s)
- Charlotte Esser
- Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany (C.E.); and Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden (A.R.)
| | - Agneta Rannug
- Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany (C.E.); and Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden (A.R.)
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23
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Hirano M, Hwang JH, Park HJ, Bak SM, Iwata H, Kim EY. In silico analysis of the interaction of avian aryl hydrocarbon receptors and dioxins to decipher isoform-, ligand-, and species-specific activations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:3795-804. [PMID: 25692546 DOI: 10.1021/es505733f] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The aryl hydrocarbon receptor (AHR) mediates toxic responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and other dioxin-like compounds (DLCs). Avian species possess multiple AHR isoforms (AHR1, AHR1β, and AHR2) that exhibit species- and isoform-specific responses to ligands. To account for the ligand preference in terms of the structural features of avian AHRs, we generated in silico homology models of the ligand-binding domain of avian AHRs based on holo human HIF-2α (PDB entry 3H7W ). Molecular docking simulations of TCDD and other DLCs with avian AHR1s and AHR2s using ASEDock indicated that the interaction energy increased with the number of substituted chlorine atoms in congeners, supporting AHR transactivation potencies and World Health Organization TCDD toxic equivalency factors of congeners. The potential interaction energies of an endogenous AHR ligand, 6-formylindolo [3,2-b] carbazole (FICZ) to avian AHRs were lower than those of TCDD, which was supported by a greater potency of FICZ for in vitro AHR-mediated transactivation than TCDD. The molecular dynamics simulation revealed that mean square displacements in Ile324 and Ser380 of TCDD-bound AHR1 of the chicken, the most sensitive species to TCDD, were smaller than those in other avian AHR1s, suggesting that the dynamic stability of these amino acid residues contribute to TCDD preference. For avian AHR2, the corresponding residues (Val/Ser or Val/Ala type) were not responsible for differential TCDD sensitivity. Application of the three-dimensional reference interaction site model showed that the stabilization of TCDD binding to avian AHRs may be due to the solvation effect depending on the characteristics of two amino acids corresponding to Ile324 and Ser380 in chicken AHR1. This study demonstrates that in silico simulations of AHRs and ligands could be used to predict isoform-, ligand-, and species-specific interactions.
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Affiliation(s)
- Masashi Hirano
- †Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama 790-8577, Japan
| | - Ji-Hee Hwang
- ‡Department of Life and Nanopharmaceutical Science and Department of Biology, Kyung Hee University, Hoegi-Dong, Dongdaemun-Gu, Seoul 130-701, Korea
| | - Hae-Jeong Park
- ‡Department of Life and Nanopharmaceutical Science and Department of Biology, Kyung Hee University, Hoegi-Dong, Dongdaemun-Gu, Seoul 130-701, Korea
| | - Su-Min Bak
- ‡Department of Life and Nanopharmaceutical Science and Department of Biology, Kyung Hee University, Hoegi-Dong, Dongdaemun-Gu, Seoul 130-701, Korea
| | - Hisato Iwata
- †Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama 790-8577, Japan
| | - Eun-Young Kim
- ‡Department of Life and Nanopharmaceutical Science and Department of Biology, Kyung Hee University, Hoegi-Dong, Dongdaemun-Gu, Seoul 130-701, Korea
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24
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Hiura Y, Satsu H, Hamada M, Shimizu M. Analysis of flavonoids regulating the expression of UGT1A1 via xenobiotic receptors in intestinal epithelial cells. Biofactors 2014; 40:336-45. [PMID: 24375494 DOI: 10.1002/biof.1153] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 11/11/2013] [Indexed: 12/23/2022]
Abstract
UDP-glucuronosyltransferase (UGT) 1A1 is one of the major metabolic enzymes for the detoxification of harmful xenobiotics in intestines, and its expression is regulated by transcription factors like the aryl hydrocarbon receptor (AhR) and the pregnane X receptor (PXR). A screening assay using real-time PCR showed that baicalein and 3-hydroxyflavone induced human UGT1A1 mRNA expression in LS180 cells. Experimental results confirmed that these flavonoids increased UGT1A protein expression as well as its enzymatic activity. The results indicated that baicalein and 3-hydroxyflavone increased the transcriptional activity of UGT1A1 via AhR and PXR, respectively. Observation via immunofluorescence microscopy suggested that baicalein and 3-hydroxyflavone further induced nuclear translocation of AhR and PXR, respectively. In addition, direct interaction between baicalein and AhR or 3-hydroxyflavone and PXR were observed using the quartz crystal microbalance method. These results elucidate the molecular mechanism of flavonoid-induced UGT1A1 gene expression via xenobiotic receptors in the intestines.
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Affiliation(s)
- Yuto Hiura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
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25
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Ligand promiscuity of aryl hydrocarbon receptor agonists and antagonists revealed by site-directed mutagenesis. Mol Cell Biol 2014; 34:1707-19. [PMID: 24591650 DOI: 10.1128/mcb.01183-13] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that can be activated by structurally diverse chemicals. To examine the mechanisms responsible for the promiscuity in AhR ligand binding, we determined the effects of mutations within the AhR ligand-binding domain (LBD) on the activity of diverse AhR ligands. Site-directed mutagenesis identified Ile319 of the mouse AhR and, to a lesser extent, Phe318 as residues involved in ligand-selective modulation of AhR transformation using a panel of 12 AhR ligands. These ligands could be categorized into four distinct structurally related groups based on their ability to activate AhR mutants at position 319 in vitro. The mutation I319K was selectively activated by FICZ and not by other examined ligands in vitro and in cell culture. F318L and F318A mutations resulted in the conversion of AhR agonists β-naphthoflavone and 3-methylcholanthrene, respectively, into partial agonists/antagonists. Hsp90 binding to the AhR was decreased with several mutations and was inversely correlated with AhR ligand-binding promiscuity. Together, these data define overlapping amino acid residues within the AhR LBD involved in the selectivity of ligand binding, the agonist or antagonist mode of ligand binding, and hsp90 binding and provide insights into the ligand diversity of AhR activators.
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26
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DeGroot DE, Denison MS. Nucleotide specificity of DNA binding of the aryl hydrocarbon receptor:ARNT complex is unaffected by ligand structure. Toxicol Sci 2014; 137:102-13. [PMID: 24136190 PMCID: PMC3924043 DOI: 10.1093/toxsci/kft234] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 10/07/2013] [Indexed: 11/14/2022] Open
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates the toxic and biological effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) and a wide variety of structurally diverse ligands through its ability to translocate into the nucleus and bind to a specific DNA recognition site (the dioxin-responsive element [DRE]) adjacent to responsive genes. Although the sequence of the DRE is well defined, several reports suggested that the nucleotide specificity of AhR DNA binding may vary depending on the structure of its bound ligand. Given the potential toxicological significance of this hypothesis, an unbiased DNA-selection-and-PCR-amplification approach was utilized to directly determine whether binding and activation of the AhR by structurally diverse agonists alter its nucleotide specificity of DNA binding. Guinea pig hepatic cytosolic AhR activated in vitro by equipotent concentrations of TCDD, 3-methylcholanthrene, β-naphthoflavone, indirubin, L-kynurenine, or YH439 was incubated with a pool of DNA oligonucleotides containing a 15-base pair variable region consisting of all possible nucleotides. The AhR-bound oligonucleotides isolated by immunoprecipitation were PCR amplified and used in subsequent rounds of selection. Sequence analysis of a total of 196 isolated oligonucleotides revealed that each ligand-activated AhR:ARNT complex only bound to DRE-containing DNA oligonucleotides; no non-DRE-containing DNA oligonucleotides were identified. These results demonstrate that the binding and activation of the AhR by structurally diverse agonists do not appear to alter its nucleotide specificity of DNA binding and suggest that stimulation of gene expression mediated by direct DNA binding of ligand-activated AhR:ARNT complexes is DRE dependent.
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Affiliation(s)
- Danica E. DeGroot
- Department of Environmental Toxicology, University of California, Davis, California 95616
| | - Michael S. Denison
- Department of Environmental Toxicology, University of California, Davis, California 95616
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Shiizaki K, Ohsako S, Kawanishi M, Yagi T. Identification of amino acid residues in the ligand-binding domain of the aryl hydrocarbon receptor causing the species-specific response to omeprazole: possible determinants for binding putative endogenous ligands. Mol Pharmacol 2013; 85:279-89. [PMID: 24265133 DOI: 10.1124/mol.113.088856] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Omeprazole (OME) induces the expression of genes encoding drug-metabolizing enzymes, such as CYP1A1, via activation of the aryl hydrocarbon receptor (AhR) both in vivo and in vitro. However, the precise mechanism of OME-mediated AhR activation is still under investigation. While elucidating species-specific susceptibility to dioxin, we found that OME-mediated AhR activation was mammalian species specific. Moreover, we previously reported that OME has inhibitory activity toward CYP1A1 enzymes. From these observations, we speculated that OME-mediated AhR target gene transcription is due to AhR activation by increasing amounts of putative AhR ligands in serum by inhibition of CYP1A1 activity. We compared the amino acid sequences of OME-sensitive rabbit AhR and nonsensitive mouse AhR to identify the residues responsible for the species-specific response. Chimeric AhRs were constructed by exchanging domains between mouse and rabbit AhRs to define the region required for the response to OME. OME-mediated transactivation was observed only with the chimeric AhR that included the ligand-binding domain (LBD) of the rabbit AhR. Site-directed mutagenesis revealed three amino acids (M328, T353, and F367) in the rabbit AhR that were responsible for OME-mediated transactivation. Replacing these residues with those of the mouse AhR abolished the response of the rabbit AhR. In contrast, substitutions of these amino acids with those of the rabbit AhR altered nonsensitive mouse AhR to become sensitive to OME. These results suggest that OME-mediated AhR activation requires a specific structure within LBD that is probably essential for binding with enigmatic endogenous ligands.
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Affiliation(s)
- Kazuhiro Shiizaki
- Division of Cancer Development System, National Cancer Center Research Institute, Tokyo, Japan (K.S.); Division of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan (S.O.); Department of Life Science, Dongguk University, Seoul, Korea (T.Y.); and Department of Biology, Graduate School of Science, Osaka Prefecture University, Osaka, Japan (M.K., T.Y.)
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28
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Quintana FJ, Sherr DH. Aryl hydrocarbon receptor control of adaptive immunity. Pharmacol Rev 2013; 65:1148-61. [PMID: 23908379 DOI: 10.1124/pr.113.007823] [Citation(s) in RCA: 244] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that belongs to the family of basic helix-loop-helix transcription factors. Although the AhR was initially recognized as the receptor mediating the pathologic effects of dioxins and other pollutants, the activation of AhR by endogenous and environmental factors has important physiologic effects, including the regulation of the immune response. Thus, the AhR provides a molecular pathway through which environmental factors modulate the immune response in health and disease. In this review, we discuss the role of AhR in the regulation of the immune response, the source and chemical nature of AhR ligands, factors controlling production and degradation of AhR ligands, and the potential to target the AhR for therapeutic immunomodulation.
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Affiliation(s)
- Francisco J Quintana
- Center for Neurologic Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
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29
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Farmahin R, Manning GE, Crump D, Wu D, Mundy LJ, Jones SP, Hahn ME, Karchner SI, Giesy JP, Bursian SJ, Zwiernik MJ, Fredricks TB, Kennedy SW. Amino acid sequence of the ligand-binding domain of the aryl hydrocarbon receptor 1 predicts sensitivity of wild birds to effects of dioxin-like compounds. Toxicol Sci 2012; 131:139-52. [PMID: 22923492 DOI: 10.1093/toxsci/kfs259] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The sensitivity of avian species to the toxic effects of dioxin-like compounds (DLCs) varies up to 1000-fold among species, and this variability has been associated with interspecies differences in aryl hydrocarbon receptor 1 ligand-binding domain (AHR1 LBD) sequence. We previously showed that LD(50) values, based on in ovo exposures to DLCs, were significantly correlated with in vitro EC(50) values obtained with a luciferase reporter gene (LRG) assay that measures AHR1-mediated induction of cytochrome P4501A in COS-7 cells transfected with avian AHR1 constructs. Those findings suggest that the AHR1 LBD sequence and the LRG assay can be used to predict avian species sensitivity to DLCs. In the present study, the AHR1 LBD sequences of 86 avian species were studied, and differences at amino acid sites 256, 257, 297, 324, 337, and 380 were identified. Site-directed mutagenesis, the LRG assay, and homology modeling highlighted the importance of each amino acid site in AHR1 sensitivity to 2,3,7,8-tetrachlorodibenzo-p-dioxin and other DLCs. The results of the study revealed that (1) only amino acids at sites 324 and 380 affect the sensitivity of AHR1 expression constructs of the 86 avian species to DLCs and (2) in vitro luciferase activity of AHR1 constructs containing only the LBD of the species of interest is significantly correlated (r (2) = 0.93, p < 0.0001) with in ovo toxicity data for those species. These results indicate promise for the use of AHR1 LBD amino acid sequences independently, or combined with the LRG assay, to predict avian species sensitivity to DLCs.
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Affiliation(s)
- Reza Farmahin
- Centre for Advanced Research in Environmental Genomics, Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
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30
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Farmahin R, Wu D, Crump D, Hervé JC, Jones SP, Hahn ME, Karchner SI, Giesy JP, Bursian SJ, Zwiernik MJ, Kennedy SW. Sequence and in vitro function of chicken, ring-necked pheasant, and Japanese quail AHR1 predict in vivo sensitivity to dioxins. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:2967-2975. [PMID: 22296185 DOI: 10.1021/es2043992] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
There are large differences in sensitivity to the toxic and biochemical effects of dioxins and dioxin-like compounds (DLCs) among vertebrates. Previously, we demonstrated that the difference in sensitivity between domestic chicken (Gallus gallus domesticus) and common tern (Sterna hirundo) to aryl hydrocarbon receptor 1 (AHR1)-dependent changes in gene expression following exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is based upon the identities of the amino acids at two sites within the ligand binding domain of AHR1 (chicken--highly sensitive; Ile324_Ser380 vs common tern--250-fold less sensitive than chicken; Val325_Ala381). Here, we tested the hypotheses that (i) the sensitivity of other avian species to TCDD, 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), and 2,3,7,8-tetrachlorodibenzofuran (TCDF) is also determined by the amino acids at sites that are equivalent to sites 324 and 380 in chicken, and (ii) Ile324_Ala380 and Val324_Ser380 genotypes confer intermediate sensitivity to DLCs in birds. We compared ligand-induced transactivation function of full-length AHR1s from chicken, common tern, ring-necked pheasant (Phasianus colchicus; Ile324_Ala380) and Japanese quail (Coturnix japonica; Val324_Ala380), and three Japanese quail AHR1 mutants. The results support our hypothesis that avian species can be grouped into three general classes of sensitivity to DLCs. Both AHR1 genotype and in vitro transactivation assays predict in vivo sensitivity. Contrary to the assumption that TCDD is the most potent DLC, PeCDF was more potent than TCDD at activating Japanese quail (13- to 26-fold) and common tern (23- to 30-fold) AHR1. Our results support and expand previous in vitro and in vivo work that demonstrated ligand-dependent species differences in AHR1 affinity. The findings and methods will be of use for DLC risk assessments.
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Affiliation(s)
- Reza Farmahin
- Centre for Advanced Research in Environmental Genomics, Department of Biology, University of Ottawa , Ottawa, Ontario K1N 6N5, Canada
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Motto I, Bordogna A, Soshilov AA, Denison MS, Bonati L. New aryl hydrocarbon receptor homology model targeted to improve docking reliability. J Chem Inf Model 2011; 51:2868-81. [PMID: 21981577 PMCID: PMC3263330 DOI: 10.1021/ci2001617] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-dependent, basic helix-loop-helix Per-ARNT-Sim (PAS) containing transcription factor that can bind and be activated by structurally diverse chemicals, including the toxic environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). As no experimentally determined structures of the AhR ligand binding domain (LBD) are available and previous homology models were only derived from apo template structures, we developed a new model based on holo X-ray structures of the hypoxia-inducible factor 2α (HIF-2α) PAS B domain, targeted to improve the accuracy of the binding site for molecular docking applications. We experimentally confirmed the ability of two HIF-2α crystallographic ligands to bind to the mAhR with relatively high affinity and demonstrated that they are AhR agonists, thus justifying the use of the holo HIF-2α structures as templates. A specific modeling/docking approach was proposed to predict the binding modes of AhR ligands in the modeled LBD. It was validated by comparison of the calculated and the experimental binding affinities of active THS ligands and TCDD for the mAhR and by functional activity analysis using several mAhR mutants generated on the basis of the modeling results. Finally the ability of the proposed approach to reproduce the different affinities of TCDD for AhRs of different species was confirmed, and a first test of its reliability in virtual screening is carried out by analyzing the correlation between the calculated and experimental binding affinities of a set of 14 PCDDs.
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Affiliation(s)
- Ilaria Motto
- Dipartimento di Scienze dell’Ambiente e del Territorio, Università degli Studi di Milano-Bicocca, Piazza della Scienza 1, 20126 Milano, Italy
| | - Annalisa Bordogna
- Dipartimento di Scienze dell’Ambiente e del Territorio, Università degli Studi di Milano-Bicocca, Piazza della Scienza 1, 20126 Milano, Italy
| | - Anatoly A. Soshilov
- Department of Environmental Toxicology, Meyer Hall, University of California, Davis, California 95616
| | - Michael S. Denison
- Department of Environmental Toxicology, Meyer Hall, University of California, Davis, California 95616
| | - Laura Bonati
- Dipartimento di Scienze dell’Ambiente e del Territorio, Università degli Studi di Milano-Bicocca, Piazza della Scienza 1, 20126 Milano, Italy
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Denison MS, Soshilov AA, He G, DeGroot DE, Zhao B. Exactly the same but different: promiscuity and diversity in the molecular mechanisms of action of the aryl hydrocarbon (dioxin) receptor. Toxicol Sci 2011; 124:1-22. [PMID: 21908767 DOI: 10.1093/toxsci/kfr218] [Citation(s) in RCA: 563] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The Ah receptor (AhR) is a ligand-dependent transcription factor that mediates a wide range of biological and toxicological effects that result from exposure to a structurally diverse variety of synthetic and naturally occurring chemicals. Although the overall mechanism of action of the AhR has been extensively studied and involves a classical nuclear receptor mechanism of action (i.e., ligand-dependent nuclear localization, protein heterodimerization, binding of liganded receptor as a protein complex to its specific DNA recognition sequence and activation of gene expression), details of the exact molecular events that result in most AhR-dependent biochemical, physiological, and toxicological effects are generally lacking. Ongoing research efforts continue to describe an ever-expanding list of ligand-, species-, and tissue-specific spectrum of AhR-dependent biological and toxicological effects that seemingly add even more complexity to the mechanism. However, at the same time, these studies are also identifying and characterizing new pathways and molecular mechanisms by which the AhR exerts its actions and plays key modulatory roles in both endogenous developmental and physiological pathways and response to exogenous chemicals. Here we provide an overview of the classical and nonclassical mechanisms that can contribute to the differential sensitivity and diversity in responses observed in humans and other species following ligand-dependent activation of the AhR signal transduction pathway.
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Affiliation(s)
- Michael S Denison
- Department of Environmental Toxicology, University of California, Davis, California 95616, USA.
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33
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Human aryl-hydrocarbon receptor and its interaction with dioxin and physiological ligands investigated by molecular modelling and docking simulations. Biochem Biophys Res Commun 2011; 413:176-81. [DOI: 10.1016/j.bbrc.2011.08.039] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 08/10/2011] [Indexed: 01/07/2023]
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34
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Correlation of dysfunction of nonmuscle myosin IIA with increased induction of Cyp1a1 in Hepa-1 cells. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1809:176-83. [PMID: 21216307 DOI: 10.1016/j.bbagrm.2011.01.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2010] [Revised: 12/20/2010] [Accepted: 01/03/2011] [Indexed: 11/20/2022]
Abstract
The aryl hydrocarbon receptor (AhR) is one of the best known ligand-activated transcription factors and it induces Cyp1a1 transcription by binding with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Recent focus has been on the relationship of AhR with signaling pathways that modulate cell shape and migration. In nonmuscle cells, nonmuscle myosin II is one of the key determinants of cell morphology, but it has not been investigated whether its function is related to Cyp1a1 induction. In this study, we observed that (-)-blebbistatin, which is a specific inhibitor of nonmuscle myosin II, increased the level of CYP1A1-mRNA in Hepa-1 cells. Comparison of (-)-blebbistatin with (+)-blebbistatin, which is an inactive enantiomer, indicated that the increase of CYP1A1-mRNA was due to nonmuscle myosin II inhibition. Subsequent knockdown experiments observed that reduction of nonmuscle myosin IIA, which is only an isoform of nonmuscle myosin II expressed in Hepa-1 cells, was related to the enhancement of TCDD-dependent Cyp1a1 induction. Moreover, chromatin immunoprecipitation assay indicated that the increase of Cyp1a1 induction was the result of transcriptional activation due to increased binding of AhR and RNA polymerase II to the enhancer and proximal promoter regions of Cyp1a1, respectively. These findings provide a new insight into the correlation between the function of nonmuscle myosin II and gene induction.
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Jogalekar AS, Reiling S, Vaz RJ. Identification of optimum computational protocols for modeling the aryl hydrocarbon receptor (AHR) and its interaction with ligands. Bioorg Med Chem Lett 2010; 20:6616-9. [DOI: 10.1016/j.bmcl.2010.09.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 09/02/2010] [Accepted: 09/07/2010] [Indexed: 10/19/2022]
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36
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Zhao B, DeGroot DE, Hayashi A, He G, Denison MS. CH223191 is a ligand-selective antagonist of the Ah (Dioxin) receptor. Toxicol Sci 2010; 117:393-403. [PMID: 20634293 PMCID: PMC2940411 DOI: 10.1093/toxsci/kfq217] [Citation(s) in RCA: 200] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 07/08/2010] [Indexed: 01/17/2023] Open
Abstract
The aryl hydrocarbon (dioxin) receptor (AhR) is a ligand-dependent transcription factor that produces a wide range of biological and toxic effects in many species and tissues. Whereas the best-characterized high-affinity ligands include structurally related halogenated aromatic hydrocarbons (HAHs) and polycyclic aromatic hydrocarbons (PAHs), the AhR is promiscuous and can also be activated by structurally diverse exogenous and endogenous chemicals. However, little is known about how these diverse ligands actually bind to and activate the AhR. Utilizing AhR ligand binding, DNA binding, and reporter gene expression assays, we have identified a novel ligand-selective antagonist (CH223191) that preferentially inhibits the ability of some classes of AhR agonists (2,3,7,8-tetrachlorodibenzo-p-dioxin and related HAHs), but not others (PAHs, flavonoids, or indirubin), to bind to and/or activate the AhR and AhR signal transduction. HAH-specific antagonism of AhR-dependent reporter gene expression by CH223191 was observed with mouse, rat, human, and guinea pig cell lines. Ligand- and species-selective antagonism was also observed with the AhR antagonists 3'-methoxy-4'-nitroflavone and 6,2',4',-trimethoxyflavone. Our results suggest that the differences in the binding by various ligands to the AhR contribute to the observed structural diversity of AhR ligands and could contribute in ligand-specific variation in AhR functionality and the toxic and biological effects of various classes of AhR agonists.
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Affiliation(s)
- Bin Zhao
- Department of Environmental Toxicology, University of California, Davis, California 95616
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Danica E. DeGroot
- Department of Environmental Toxicology, University of California, Davis, California 95616
| | - Ai Hayashi
- Department of Environmental Toxicology, University of California, Davis, California 95616
| | - Guochun He
- Department of Environmental Toxicology, University of California, Davis, California 95616
| | - Michael S. Denison
- Department of Environmental Toxicology, University of California, Davis, California 95616
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Yoshikawa E, Miyagi S, Dedachi K, Ishihara-Sugano M, Itoh S, Kurita N. Specific interactions between aryl hydrocarbon receptor and dioxin congeners: Ab initio fragment molecular orbital calculations. J Mol Graph Model 2010; 29:197-205. [DOI: 10.1016/j.jmgm.2010.06.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Revised: 06/16/2010] [Accepted: 06/17/2010] [Indexed: 11/30/2022]
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Whelan F, Hao N, Furness SGB, Whitelaw ML, Chapman-Smith A. Amino acid substitutions in the aryl hydrocarbon receptor ligand binding domain reveal YH439 as an atypical AhR activator. Mol Pharmacol 2010; 77:1037-46. [PMID: 20231332 DOI: 10.1124/mol.109.062927] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The aryl hydrocarbon receptor (AhR) is traditionally defined as a transcription factor activated by exogenous polyaromatic and halogenated aromatic hydrocarbon (PAH/HAH) ligands. Active AhR induces genes involved in xenobiotic metabolism, including cytochrome P4501A1, which function to metabolize activating ligands. However, recent studies implicate AhR in biological events that are apparently unrelated to the xenobiotic response, implying that endogenous activation mechanisms exist. Three AhR genes in zebrafish (Danio rerio) encode proteins that demonstrate differential activation in response to PAH/HAHs, with the nonresponsive drAhR1a having some sequence divergence from the PAH/HAH-responsive AhRs in the ligand binding domain (LBD). We used these differences to guide the mutagenesis of mouse AhR (mAhR), aiming to generate variants that functionally discriminate between activation mechanisms. We found substitution of histidine 285 in the LBD with tyrosine gave a receptor that could be activated by isopropyl-2-(1,3-dithietane-2-ylidene)-2-[N-(4-methylthiazol-2-yl)carbamoyl]acetate (YH439), a potential AhR ligand chemically distinct from classic PAH/HAH-type ligands, but prevented activation by both exogenous PAH/HAH ligands and the endogenous activation mimics of suspension culture and application of shear-stressed serum. The differential response of H285Y mAhR to YH439 suggests that this activator has a novel mode of interaction that tolerates tyrosine at position 285 in the LBD and is distinct from the binding mode of the well characterized PAH/HAH ligands. In support of this, the PAH-type antagonist 3',4'-dimethoxyflavone blocked mAhR activation by 2,3,7,8-tetrachlorodibenzo-p-dioxin but not YH439. Furthermore, the strict correlation between response to exogenous PAH/HAH ligands and mimics of endogenous activation suggests that a PAH-type ligand may underpin endogenous mechanisms of activation.
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Affiliation(s)
- Fiona Whelan
- Department of Biochemistry, School of Molecular and Biomedical Science, University of Adelaide, North Tce, Adelaide, SA 5005, Australia
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Marshall NB, Kerkvliet NI. Dioxin and immune regulation: emerging role of aryl hydrocarbon receptor in the generation of regulatory T cells. Ann N Y Acad Sci 2010; 1183:25-37. [PMID: 20146706 DOI: 10.1111/j.1749-6632.2009.05125.x] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The immune toxicity of the ubiquitous environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), commonly referred to as dioxin, has been studied for over 35 years but only recently has the profound immune suppression induced by TCDD exposure been linked to induction of regulatory T cells (Tregs). The effects of TCDD are mediated through its binding to the aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor. The subsequent AHR-dependent effects on immune responses are determined by the cell types involved, their activation status, and the type of antigenic stimulus. Collectively, studies indicate that TCDD inhibits CD4+ T cell differentiation into T helper (Th)1, Th2, and Th17 effector cells, while inducing Foxp3-negative and/or preserving Foxp3+ Tregs. Although it is not yet clear how activation of AHR by TCDD induces Tregs, there is a potential therapeutic role for alternative AHR ligands in the treatment of immune-mediated disorders.
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Affiliation(s)
- Nikki B Marshall
- Department of Microbiology, Environmental Health Sciences Center, Oregon State University, Corvallis, OR 97331, USA
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Zhou H, Qu Y, Wu H, Liao C, Zheng J, Diao X, Xue Q. Molecular phylogenies and evolutionary behavior of AhR (aryl hydrocarbon receptor) pathway genes in aquatic animals: implications for the toxicology mechanism of some persistent organic pollutants (POPs). CHEMOSPHERE 2010; 78:193-205. [PMID: 19853884 DOI: 10.1016/j.chemosphere.2009.09.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2009] [Revised: 07/15/2009] [Accepted: 09/03/2009] [Indexed: 05/28/2023]
Abstract
Phylogenetic analysis of AhR pathway genes and their evolutionary rate variations were studied on aquatic animals. The gene sequences for the proteins involved in this pathway were obtained from four major phylogenetic groups, including bivalvia, amphibian, teleostei and mammalia. These genes were distributed under four major steps of toxicology regulation: formation of cytosolic complex, translocation of AhR, heterodimerization of AhR and induction of CYP1A. The NJ, MP, and ML algorithm were used on protein coding DNA sequences to deduce the evolutionary relationship for the respective AhR pathway gene among different aquatic animals. The rate of non-synonymous nucleotide substitutions per non-synonymous site (d(N)) and synonymous nucleotide substitutions per synonymous site (d(S)) were calculated for different clade of the respective phylogenetic tree for each AhR pathway gene. The phylogenetic analysis suggests that evolutionary pattern of AhR pathway genes in aquatic animals is characterized mainly through gene duplication events or alterative splicing. The d(N) values indicate that all AhR pathway genes are well conserved in aquatic animals, except for CYP1A gene. Furthermore, compare with other aquatic animals, the d(N) value indicates that AhR pathway genes of fish are less conserved, and these genes likely go through an adaptive evolution within aquatic animals.
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Affiliation(s)
- Hailong Zhou
- Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
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41
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Bisson WH, Koch DC, O'Donnell EF, Khalil SM, Kerkvliet NI, Tanguay RL, Abagyan R, Kolluri SK. Modeling of the aryl hydrocarbon receptor (AhR) ligand binding domain and its utility in virtual ligand screening to predict new AhR ligands. J Med Chem 2009; 52:5635-41. [PMID: 19719119 DOI: 10.1021/jm900199u] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor; the AhR Per-AhR/Arnt-Sim (PAS) domain binds ligands. We developed homology models of the AhR PAS domain to characterize previously observed intra- and interspecies differences in ligand binding using molecular docking. In silico structure-based virtual ligand screening using our model resulted in the identification of pinocembrin and 5-hydroxy-7-methoxyflavone, which promoted nuclear translocation and transcriptional activation of AhR and AhR-dependent induction of endogenous target genes.
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Affiliation(s)
- William H Bisson
- Cancer Biology Laboratory, Environmental Health Sciences Center, Oregon State University, Corvallis, Oregon 97331, USA
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42
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Krämer S, Testa B. The Biochemistry of Drug Metabolism - An Introduction. Chem Biodivers 2009; 6:1477-660, table of contents. [DOI: 10.1002/cbdv.200900233] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Pandini A, Soshilov AA, Song Y, Zhao J, Bonati L, Denison MS. Detection of the TCDD binding-fingerprint within the Ah receptor ligand binding domain by structurally driven mutagenesis and functional analysis. Biochemistry 2009; 48:5972-83. [PMID: 19456125 PMCID: PMC2859071 DOI: 10.1021/bi900259z] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-dependent, basic helix-loop-helix Per-Arnt-Sim (PAS)-containing transcription factor that can bind and be activated by structurally diverse chemicals, including the toxic environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Our previous three-dimensional homology model of the mouse AhR (mAhR) PAS B ligand binding domain allowed identification of the binding site and its experimental validation. We have extended this analysis by conducting comparative structural modeling studies of the ligand binding domains of six additional high-affinity mammalian AhRs. These results, coupled with site-directed mutagenesis and AhR functional analysis, have allowed detection of the "TCDD binding-fingerprint" of conserved residues within the ligand binding cavity necessary for high-affinity TCDD binding and TCDD-dependent AhR transformation DNA binding. The essential role of selected residues was further evaluated using molecular docking simulations of TCDD with both wild-type and mutant mAhRs. Taken together, our results dramatically improve our understanding of the molecular determinants of TCDD binding and provide a basis for future studies directed toward rationalizing the observed species differences in AhR sensitivity to TCDD and understanding the mechanistic basis for the dramatic diversity in AhR ligand structure.
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Affiliation(s)
- Alessandro Pandini
- Division of Mathematical Biology, National Institute for Medical Research, The Ridgeway, London NW7 1AA, U.K
| | - Anatoly A. Soshilov
- Department of Environmental Toxicology, Meyer Hall, University of California, Davis, California 95616
| | - Yujuan Song
- Department of Environmental Toxicology, Meyer Hall, University of California, Davis, California 95616
| | - Jing Zhao
- Department of Environmental Toxicology, Meyer Hall, University of California, Davis, California 95616
| | - Laura Bonati
- Dipartimento di Scienze dell’Ambiente e del Territorio, Università degli Studi di Milano-Bicocca, Piazza della Scienza, 1, 20126 Milano, Italy
| | - Michael S. Denison
- Department of Environmental Toxicology, Meyer Hall, University of California, Davis, California 95616
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Characterization of the region of the aryl hydrocarbon receptor required for ligand dependency of transactivation using chimeric receptor between Drosophila and Mus musculus. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2009; 1789:477-86. [PMID: 19560568 DOI: 10.1016/j.bbagrm.2009.06.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 06/17/2009] [Accepted: 06/17/2009] [Indexed: 02/08/2023]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcriptional factor. Although 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is high affinity and toxic to many vertebrate animals, invertebrate AhRs including Drosophila melanogaster AhR (spineless) have no ability to bind exogenous chemicals as ligands. To analyze the ligand-binding domain (LBD) of AhR, we used chimeras between mouse and Drosophila AhR. The chimeric AhR revealed that the LBD determines constitutive transactivation in Drosophila AhR or ligand-dependent activation in mouse AhR. The LBD was further divided into three blocks that corresponded to amino acids 230-300, 301-361, and 361-420 of the mouse sequence. Six chimeric proteins clarified that amino acids 291-350 of the Drosophila LBD, i.e. the middle region, were required to keep the protein in the active form in the absence of ligand binding, whereas in the mouse AhR, this region was required to maintain the protein in the inactive form in the absence of ligand. Furthermore, Arg346 in the middle region of the mouse LBD, was identified as amino acids that were critical for AhR activation by site-directed mutagenesis.
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Amakura Y, Tsutsumi T, Sasaki K, Nakamura M, Yoshida T, Maitani T. Influence of food polyphenols on aryl hydrocarbon receptor-signaling pathway estimated by in vitro bioassay. PHYTOCHEMISTRY 2008; 69:3117-30. [PMID: 17869316 DOI: 10.1016/j.phytochem.2007.07.022] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 06/08/2007] [Accepted: 07/17/2007] [Indexed: 05/17/2023]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates the toxic and biological actions of many aromatic environmental pollutants such as dioxins. We investigated AhR activation by some vegetable constituents, including flavonoids, tannins, and related polyphenols, using an AhR-based in vitro bioassay for dioxins. Among the compounds tested, marked AhR activation was exhibited by isoflavones such as daidzein, resveratrol (a stilbene) structure, some flavanones such as naringenin, and flavones such as baicalein. On the other hand, some flavones such as apigenin, flavonols such as quercetin, and anthraquinones such as emodin, showed notable inhibitory effects on the in vitro activation of AhR induced by the dioxin [2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)]. In addition, AhR-mediated interactions between AhR and some plant extracts, including those from vegetables, fruits, herbs, and teas, were tested by using the AhR-based bioassay. Of the samples tested, some leafy green vegetables, citrus fruits, and herbs that contain food polyphenolics showed AhR-based interactions at high concentrations. On the basis of these finding, we discuss the implications of polyphenols on the AhR-signaling pathway.
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Affiliation(s)
- Yoshiaki Amakura
- College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama, Ehime 790-8578, Japan.
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46
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Head JA, Hahn ME, Kennedy SW. Key amino acids in the aryl hydrocarbon receptor predict dioxin sensitivity in avian species. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:7535-7541. [PMID: 18939598 DOI: 10.1021/es801082a] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Dioxin-like compounds are toxic to most vertebrates, but significant differences in sensitivity exist among species. A recent study suggests that the amino acid residues corresponding to Ile324 and Ser380 in the chicken aryl hydrocarbon receptor 1 (AHR1) are important determinants of differential biochemical responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in chickens and common terns. Here, we investigate whether the identity of these amino acid residues can predict embryonic sensitivity to dioxin-like compounds in a wide range of birds. AHR1 sequences were determined in species for which sensitivity data were available. Of all the species surveyed, chickens were unique in having the Ile/Ser genotype and were also the most sensitive to dioxin-like compounds. Turkeys, ring-necked pheasants, and Eastern bluebirds (intermediate Ile/Ala genotype) were less sensitive than chickens but more sensitive than American kestrels, common terns, double-crested cormorants, Japanese quail, herring gulls, or ducks (Val/ Ala genotype). Our work suggests that key amino acids in the AHR1 ligand binding domain are predictive of broad categories of dioxin sensitivity in avian species. Given the large degree of variation in species sensitivity and the paucity of species-specific toxicity data, a genetic screen based on these findings could substantially improve risk assessment for dioxin-like compounds in wild birds.
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Affiliation(s)
- Jessica A Head
- Department of Biology, Centre for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa, Ontario, Canada
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Henry EC, Gasiewicz TA. Molecular determinants of species-specific agonist and antagonist activity of a substituted flavone towards the aryl hydrocarbon receptor. Arch Biochem Biophys 2008; 472:77-88. [PMID: 18294953 DOI: 10.1016/j.abb.2008.02.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Revised: 02/05/2008] [Accepted: 02/06/2008] [Indexed: 11/30/2022]
Abstract
The aryl hydrocarbon receptor (AhR) mediates the toxicity of dioxins and related xenobiotics. Other chemicals also bind the AhR to elicit either agonist or antagonist responses. Here we used site-directed mutagenesis within the ligand binding domain of murine AhR to probe for specific residues that might interact differentially with the antagonist 3'-methoxy-4'-nitroflavone (MNF) compared with the prototypical agonist TCDD. Reduced (3)H-TCDD binding, dioxin-response element (DRE) binding, and transcriptional activity were observed for several point mutants. One mutation, R355I, changed the response to MNF from antagonist to agonist. Notably, Ile is the residue found in the guinea pig AhR, towards which MNF has partial agonist activity in contrast to its strong antagonist activity in mouse. A similar reversal of response to MNF was observed in chimeric AhRs in which the C-terminal region of mAhR was replaced with the guinea pig C-terminal region. These data demonstrate that different amino acids can be important in binding of different AhR ligands and can mediate distinct responses. The ultimate response of the AhR also depends on how other portions of the receptor protein are functionally coupled to the initial ligand binding event.
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Affiliation(s)
- E C Henry
- Department of Environmental Medicine, University of Rochester Medical Center, 575 Elmwood Ave, Box EHSC, Rochester, NY 14642, USA.
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