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Mosa FES, Alqahtani MA, El-Ghiaty MA, Dyck JRB, Barakat K, El-Kadi AOS. Identification of aryl hydrocarbon receptor allosteric antagonists from clinically approved drugs. Drug Dev Res 2024; 85:e22232. [PMID: 38992915 DOI: 10.1002/ddr.22232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2024] [Revised: 06/14/2024] [Accepted: 06/30/2024] [Indexed: 07/13/2024]
Abstract
The human aryl hydrocarbon receptor (AhR), a ligand-dependent transcription factor, plays a pivotal role in a diverse array of pathways in biological and pathophysiological events. This position AhR as a promising target for both carcinogenesis and antitumor strategies. In this study we utilized computational modeling to screen and identify FDA-approved drugs binding to the allosteric site between α2 of bHLH and PAS-A domains of AhR, with the aim of inhibiting its canonical pathway activity. Our findings indicated that nilotinib effectively fits into the allosteric pocket and forms interactions with crucial residues F82, Y76, and Y137. Binding free energy value of nilotinib is the lowest among top hits and maintains stable within its pocket throughout entire (MD) simulations time. Nilotinib has also substantial interactions with F295 and Q383 when it binds to orthosteric site and activate AhR. Surprisingly, it does not influence AhR nuclear translocation in the presence of AhR agonists; instead, it hinders the formation of the functional AhR-ARNT-DNA heterodimer assembly, preventing the upregulation of regulated enzymes like CYP1A1. Importantly, nilotinib exhibits a dual impact on AhR, modulating AhR activity via the PAS-B domain and working as a noncompetitive allosteric antagonist capable of blocking the canonical AhR signaling pathway in the presence of potent AhR agonists. These findings open a new avenue for the repositioning of nilotinib beyond its current application in diverse diseases mediated via AhR.
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Affiliation(s)
- Farag E S Mosa
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Mohammed A Alqahtani
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Mahmoud A El-Ghiaty
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Jason R B Dyck
- Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Khaled Barakat
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Ayman O S El-Kadi
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
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2
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Bonati L, Motta S, Callea L. The AhR Signaling Mechanism: A Structural Point of View. J Mol Biol 2024; 436:168296. [PMID: 37797832 DOI: 10.1016/j.jmb.2023.168296] [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: 07/28/2023] [Revised: 09/23/2023] [Accepted: 09/28/2023] [Indexed: 10/07/2023]
Abstract
The Aryl hydrocarbon Receptor (AhR) is a well-known sensor of xenobiotics; moreover, it is considered a promising drug target as it is involved in the regulation of many patho-physiological processes. For these reasons the study of its ligand-activated transcription mechanism has stimulated several studies for over twenty years. In this review we highlight the key role of molecular structural information in understanding the different steps of the signaling mechanism. The architecture of the AhR cytosolic complex, encompassing the hsp90 chaperone protein and the XAP2 and p23 co-chaperones, has become available in the last year thanks to Cryo-EM experiments. The structure of the AhR ligand-binding (PAS-B) domain has remained elusive for a long time; it has been predicted by homology modelling, based on known PAS systems, and its ligand-bound forms were modelled through ligand molecular docking. Although very recently some structural information on this domain has become available, considerable efforts are still needed to determine the binding geometries of the AhR key ligands by experimental high-resolution studies. On the other hand, the dimeric structure of AhR with the ARNT protein, bound to the specific DNA responsive element, was partially determined by X-ray crystallography and it was completed by homology modelling. On the whole the current structural knowledge of the main protein complexes that form over the AhR mechanism opens the way to confirm and further investigate the main steps of the proposed ligand-activated transcription mechanism of the AhR.
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Affiliation(s)
- Laura Bonati
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza 1, 20126 Milan, Italy.
| | - Stefano Motta
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza 1, 20126 Milan, Italy.
| | - Lara Callea
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza 1, 20126 Milan, Italy.
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3
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Ondrová K, Zůvalová I, Vyhlídalová B, Krasulová K, Miková E, Vrzal R, Nádvorník P, Nepal B, Kortagere S, Kopečná M, Kopečný D, Šebela M, Rastinejad F, Pu H, Soural M, Rolfes KM, Haarmann-Stemmann T, Li H, Mani S, Dvořák Z. Monoterpenoid aryl hydrocarbon receptor allosteric antagonists protect against ultraviolet skin damage in female mice. Nat Commun 2023; 14:2728. [PMID: 37169746 PMCID: PMC10174618 DOI: 10.1038/s41467-023-38478-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 05/02/2023] [Indexed: 05/13/2023] Open
Abstract
The human aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that is a pivotal regulator of human physiology and pathophysiology. Allosteric inhibition of AhR was previously thought to be untenable. Here, we identify carvones as noncompetitive, insurmountable antagonists of AhR and characterize the structural and functional consequences of their binding. Carvones do not displace radiolabeled ligands from binding to AhR but instead bind allosterically within the bHLH/PAS-A region of AhR. Carvones do not influence the translocation of ligand-activated AhR into the nucleus but inhibit the heterodimerization of AhR with its canonical partner ARNT and subsequent binding of AhR to the promoter of CYP1A1. As a proof of concept, we demonstrate physiologically relevant Ahr-antagonism by carvones in vivo in female mice. These substances establish the molecular basis for selective targeting of AhR regardless of the type of ligand(s) present and provide opportunities for the treatment of disease processes modified by AhR.
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Affiliation(s)
- Karolína Ondrová
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Iveta Zůvalová
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Barbora Vyhlídalová
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Kristýna Krasulová
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Eva Miková
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Radim Vrzal
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Petr Nádvorník
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Binod Nepal
- Department of Microbiology & Immunology, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Sandhya Kortagere
- Department of Microbiology & Immunology, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Martina Kopečná
- Department of Experimental Biology, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - David Kopečný
- Department of Experimental Biology, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Marek Šebela
- Department of Biochemistry, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Fraydoon Rastinejad
- Target Discovery Institute Nuffield Department of Medicine Research Building Brasenose College University of Oxford, Oxford, UK
| | - Hua Pu
- Target Discovery Institute Nuffield Department of Medicine Research Building Brasenose College University of Oxford, Oxford, UK
| | - Miroslav Soural
- Department of Organic Chemistry, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | | | | | - Hao Li
- Department of Medicine, Oncology, Molecular Pharmacology, and Genetics, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Sridhar Mani
- Department of Medicine, Oncology, Molecular Pharmacology, and Genetics, Albert Einstein College of Medicine, Bronx, NY, USA.
| | - Zdeněk Dvořák
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University, Olomouc, Czech Republic.
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4
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Dai S, Qu L, Li J, Zhang Y, Jiang L, Wei H, Guo M, Chen X, Chen Y. Structural insight into the ligand binding mechanism of aryl hydrocarbon receptor. Nat Commun 2022; 13:6234. [PMID: 36266304 PMCID: PMC9585082 DOI: 10.1038/s41467-022-33858-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 10/04/2022] [Indexed: 12/25/2022] Open
Abstract
The aryl hydrocarbon receptor (AHR), a member of the basic helix-loop-helix (bHLH) Per-Arnt-Sim (PAS) family of transcription factors, plays important roles in regulating xenobiotic metabolism, cellular differentiation, stem cell maintenance, as well as immunity. More recently, AHR has gained significant interest as a drug target for the development of novel cancer immunotherapy drugs. Detailed understanding of AHR-ligand binding has been hampered for decades by the lack of a three-dimensional structure of the AHR PAS-B domain. Here, we present multiple crystal structures of the Drosophila AHR PAS-B domain, including its apo, ligand-bound, and AHR nuclear translocator (ARNT) PAS-B-bound forms. Together with biochemical and cellular assays, our data reveal structural features of the AHR PAS-B domain, provide insights into the mechanism of AHR ligand binding, and provide the structural basis for the future development of AHR-targeted therapeutics.
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Affiliation(s)
- Shuyan Dai
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
| | - Lingzhi Qu
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
| | - Jun Li
- grid.461579.8Institute of Clinical Medicine, The First Affiliated Hospital of University of South China, Hengyang, Hunan 421001 China
| | - Ye Zhang
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
| | - Longying Jiang
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
| | - Hudie Wei
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
| | - Ming Guo
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
| | - Xiaojuan Chen
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
| | - Yongheng Chen
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
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5
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Current Therapeutic Landscape and Safety Roadmap for Targeting the Aryl Hydrocarbon Receptor in Inflammatory Gastrointestinal Indications. Cells 2022; 11:cells11101708. [PMID: 35626744 PMCID: PMC9139855 DOI: 10.3390/cells11101708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/30/2022] [Accepted: 05/16/2022] [Indexed: 02/07/2023] Open
Abstract
Target modulation of the AhR for inflammatory gastrointestinal (GI) conditions holds great promise but also the potential for safety liabilities both within and beyond the GI tract. The ubiquitous expression of the AhR across mammalian tissues coupled with its role in diverse signaling pathways makes development of a “clean” AhR therapeutically challenging. Ligand promiscuity and diversity in context-specific AhR activation further complicates targeting the AhR for drug development due to limitations surrounding clinical translatability. Despite these concerns, several approaches to target the AhR have been explored such as small molecules, microbials, PROTACs, and oligonucleotide-based approaches. These various chemical modalities are not without safety liabilities and require unique de-risking strategies to parse out toxicities. Collectively, these programs can benefit from in silico and in vitro methodologies that investigate specific AhR pathway activation and have the potential to implement thresholding parameters to categorize AhR ligands as “high” or “low” risk for sustained AhR activation. Exploration into transcriptomic signatures for AhR safety assessment, incorporation of physiologically-relevant in vitro model systems, and investigation into chronic activation of the AhR by structurally diverse ligands will help address gaps in our understanding regarding AhR-dependent toxicities. Here, we review the role of the AhR within the GI tract, novel therapeutic modality approaches to target the AhR, key AhR-dependent safety liabilities, and relevant strategies that can be implemented to address drug safety concerns. Together, this review discusses the emerging therapeutic landscape of modalities targeting the AhR for inflammatory GI indications and offers a safety roadmap for AhR drug development.
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6
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Kou Z, Dai W. Aryl hydrocarbon receptor: Its roles in physiology. Biochem Pharmacol 2021; 185:114428. [PMID: 33515530 DOI: 10.1016/j.bcp.2021.114428] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 01/15/2021] [Accepted: 01/19/2021] [Indexed: 12/27/2022]
Abstract
Aryl hydrocarbon receptor (AHR) was initially discovered as a cellular protein involved in mediating the detoxification of xenobiotic compounds. Extensive research in the past two decades has identified several families of physiological ligands and uncovered important functions of AHR in normal development and homeostasis. Deficiency in AHR expression disrupts major signaling systems and transcriptional programs, which appear to be responsible for the development of numerous developmental abnormalities including cardiac hypertrophy and epidermal hyperplasia. This mini review primarily summarizes recent advances in our understanding of AHR functions in normal physiology with an emphasis on the cardiovascular, gastrointestinal, integumentary, nervous, and immunomodulatory systems.
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Affiliation(s)
- Ziyue Kou
- Department of Environmental Medicine, New York University Langone Medical Center, NY 10010, United States
| | - Wei Dai
- Department of Environmental Medicine, New York University Langone Medical Center, NY 10010, United States.
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7
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Aftabi Y, Rafei S, Zarredar H, Amiri-Sadeghan A, Akbari-Shahpar M, Khoshkam Z, Seyedrezazadeh E, Khalili M, Mehrnejad F, Fereidouni S, Lawrence BP. Refinement of coding SNPs in the human aryl hydrocarbon receptor gene using ISNPranker: An integrative-SNP ranking web-tool. Comput Biol Chem 2020; 90:107416. [PMID: 33264727 DOI: 10.1016/j.compbiolchem.2020.107416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 11/06/2020] [Accepted: 11/10/2020] [Indexed: 12/14/2022]
Abstract
Different bioinformatic methods apply various approaches to predict how much the effect of a SNP could be deleterious and therefore their results may differ significantly. However, variation studies often need to consider an integrated prediction result to analyze the effect of SNPs. To address this problem, we used an algorithm to map ordinal predictions to a numeral space and averaging them, and based on it we developed the ISNPranker web-tool (http://isnpranker.semilab.ir/). It takes heterogonous outputs of different predictors and generates integrated numerical predictions and ranks SNPs based on them. Afterward, we used ISNPranker to identify the most deleterious coding SNPs (cSNPs) of the human aryl hydrocarbon receptor (AHR) gene. AHR is a ligand-activated transcription factor that governs many molecular and cellular mechanisms and cSNPs may affect its structure, interactions, and function. Forty validated cSNPs of AHR were initially analyzed using 16 publicly available SNP analyzers and the results were introduced to the ISNPranker and integrated predictions were obtained. The cSNPs were ranked in 34 levels of danger and rs200257782 in the ARNT dimerization domain (ADD121-289) of AHR was identified as the most deleterious cSNP. The rs148360742, which affect ADD40-79 and Hsp90 binding domain (HBD27-79) was in the second rank and the third and fourth ranks were occupied by ADD121-289-located variations rs571123681 and rs141667112 respectively. In conclusion, we introduced ISNPranker, which is a web-tool for integrative ranking of SNPs, and we showed that AHR structure and function may be highly sensitive to the cSNPs in the ARNT dimerization domain.
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Affiliation(s)
- Younes Aftabi
- Tuberculosis and Lung Diseases Research Center, Tabriz University of Medical Sciences, P.O. Box: 53714161, Tabriz, Iran.
| | - Saleh Rafei
- Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization, Karaj, Iran
| | - Habib Zarredar
- Tuberculosis and Lung Diseases Research Center, Tabriz University of Medical Sciences, P.O. Box: 53714161, Tabriz, Iran
| | - Amir Amiri-Sadeghan
- Tuberculosis and Lung Diseases Research Center, Tabriz University of Medical Sciences, P.O. Box: 53714161, Tabriz, Iran
| | - Mohsen Akbari-Shahpar
- Department of Computer Engineering, Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz, Iran
| | - Zahra Khoshkam
- Tuberculosis and Lung Diseases Research Center, Tabriz University of Medical Sciences, P.O. Box: 53714161, Tabriz, Iran; Department of Molecular and Cell Biology, Faculty of Basic Sciences, University of Tehran, Tehran, Iran
| | - Ensiyeh Seyedrezazadeh
- Tuberculosis and Lung Diseases Research Center, Tabriz University of Medical Sciences, P.O. Box: 53714161, Tabriz, Iran
| | - Majid Khalili
- Tuberculosis and Lung Diseases Research Center, Tabriz University of Medical Sciences, P.O. Box: 53714161, Tabriz, Iran
| | - Faramarz Mehrnejad
- Department of Life Science Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran
| | - Sasan Fereidouni
- Department of Interdisciplinary Life Sciences, University of Veterinary Medicine Vienna, Vienna, Austria
| | - B Paige Lawrence
- Departments of Environmental Medicine and Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, USA
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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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Transitional States in Ligand-Dependent Transformation of the Aryl Hydrocarbon Receptor into Its DNA-Binding Form. Int J Mol Sci 2020; 21:ijms21072474. [PMID: 32252465 PMCID: PMC7177239 DOI: 10.3390/ijms21072474] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 03/20/2020] [Accepted: 03/30/2020] [Indexed: 01/03/2023] Open
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates the biological and toxicological effects of an AhR lacking the entire PASB structurally diverse chemicals, including halogenated aromatic hydrocarbons. Ligand-dependent transformation of the AhR into its DNA binding form involves a ligand-dependent conformational change, heat shock protein 90 (hsp90), dissociation from the AhR complex and AhR dimerization with the AhR nuclear translocator (ARNT) protein. The mechanism of AhR transformation was examined using mutational approaches and stabilization of the AhR:hsp90 complex with sodium molybdate. Insertion of a single mutation (F281A) in the hsp90-binding region of the AhR resulted in its constitutive (ligand-independent) transformation/DNA binding in vitro. Mutations of AhR residues within the Arg-Cys-rich region (R212A, R217A, R219A) and Asp371 (D371A) impaired AhR transformation without a significant effect on ligand binding. Stabilization of AhR:hsp90 binding with sodium molybdate decreased transformation/DNA binding of the wild type AhR but had no effect on constitutively active AhR mutants. Interestingly, transformation of the AhR in the presence of molybdate allowed detection of an intermediate transformation ternary complex containing hsp90, AhR, and ARNT. These results are consistent with a stepwise transformation mechanism in which binding of ARNT to the liganded AhR:hsp90 complex results in a progressive displacement of hsp90 and conversion of the AhR into its high affinity DNA binding form. The available molecular insights into the signaling mechanism of other Per-ARNT-Sim (PAS) domains and structural information on hsp90 association with other client proteins are consistent with the proposed transformation mechanism of the AhR.
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10
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Puyskens A, Stinn A, van der Vaart M, Kreuchwig A, Protze J, Pei G, Klemm M, Guhlich-Bornhof U, Hurwitz R, Krishnamoorthy G, Schaaf M, Krause G, Meijer AH, Kaufmann SHE, Moura-Alves P. Aryl Hydrocarbon Receptor Modulation by Tuberculosis Drugs Impairs Host Defense and Treatment Outcomes. Cell Host Microbe 2019; 27:238-248.e7. [PMID: 31901518 DOI: 10.1016/j.chom.2019.12.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 10/30/2019] [Accepted: 12/06/2019] [Indexed: 12/20/2022]
Abstract
Antimicrobial resistance in tuberculosis (TB) is a public health threat of global dimension, worsened by increasing drug resistance. Host-directed therapy (HDT) is an emerging concept currently explored as an adjunct therapeutic strategy for TB. One potential host target is the ligand-activated transcription factor aryl hydrocarbon receptor (AhR), which binds TB virulence factors and controls antibacterial responses. Here, we demonstrate that in the context of therapy, the AhR binds several TB drugs, including front line drugs rifampicin (RIF) and rifabutin (RFB), resulting in altered host defense and drug metabolism. AhR sensing of TB drugs modulates host defense mechanisms, notably impairs phagocytosis, and increases TB drug metabolism. Targeting AhR in vivo with a small-molecule inhibitor increases RFB-treatment efficacy. Thus, the AhR markedly impacts TB outcome by affecting both host defense and drug metabolism. As a corollary, we propose the AhR as a potential target for HDT in TB in adjunct to canonical chemotherapy.
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Affiliation(s)
- Andreas Puyskens
- Department of Immunology, Max Planck Institute for Infection Biology, Charitéplatz 1, Berlin 10117, Germany
| | - Anne Stinn
- Department of Immunology, Max Planck Institute for Infection Biology, Charitéplatz 1, Berlin 10117, Germany; Department for Structural Infection Biology, Center for Structural Systems Biology, Notkestraße 85, Hamburg 22607, Germany
| | - Michiel van der Vaart
- Institute of Biology, Leiden University, Sylviusweg 72, Leiden 2333, the Netherlands
| | - Annika Kreuchwig
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, Berlin 13125, Germany
| | - Jonas Protze
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, Berlin 13125, Germany
| | - Gang Pei
- Institute of Immunology, Friedrich Loeffler Institute, Südufer 10, Greifswald-Insel Riems 17493, Germany
| | - Marion Klemm
- Department of Immunology, Max Planck Institute for Infection Biology, Charitéplatz 1, Berlin 10117, Germany
| | - Ute Guhlich-Bornhof
- Department of Immunology, Max Planck Institute for Infection Biology, Charitéplatz 1, Berlin 10117, Germany
| | - Robert Hurwitz
- Protein Purification Core Facility, Max Planck Institute for Infection Biology, Charitéplatz 1, Berlin 10117, Germany
| | - Gopinath Krishnamoorthy
- Department of Immunology, Max Planck Institute for Infection Biology, Charitéplatz 1, Berlin 10117, Germany
| | - Marcel Schaaf
- Institute of Biology, Leiden University, Sylviusweg 72, Leiden 2333, the Netherlands
| | - Gerd Krause
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, Berlin 13125, Germany
| | - Annemarie H Meijer
- Institute of Biology, Leiden University, Sylviusweg 72, Leiden 2333, the Netherlands
| | - Stefan H E Kaufmann
- Department of Immunology, Max Planck Institute for Infection Biology, Charitéplatz 1, Berlin 10117, Germany; Hagler Institute for Advanced Study at Texas A&M University, College Station, TX 77843, USA.
| | - Pedro Moura-Alves
- Department of Immunology, Max Planck Institute for Infection Biology, Charitéplatz 1, Berlin 10117, Germany; Ludwig Institute for Cancer Research, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7DQ, UK.
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11
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Conformational ensemble of an intrinsically flexible loop in mitochondrial import protein Tim21 studied by modeling and molecular dynamics simulations. Biochim Biophys Acta Gen Subj 2019; 1864:129417. [PMID: 31445064 DOI: 10.1016/j.bbagen.2019.129417] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 08/12/2019] [Accepted: 08/17/2019] [Indexed: 11/20/2022]
Abstract
BACKGROUND Tim21, a subunit of a highly dynamic translocase of the inner mitochondrial membrane (TIM23) complex, translocates proteins by interacting with subunits in the translocase of the outer membrane (TOM) complex and Tim23 channel in the TIM23 complex. A loop segment in Tim21, which is in close proximity of the binding site of Tim23, has different conformations in X-ray, NMR and new crystal contact-free space (CCFS) structures. MD simulations can provide information on the structure and dynamics of the loop in solution. METHODS The conformational ensemble of the loop was characterized using loop modeling and molecular dynamics (MD) simulations. RESULTS MD simulations confirmed mobility of the loop. Multidimensional scaling and clustering were used to characterize the dynamic conformational ensemble of the loop. Free energy landscape showed that the CCFS crystal structure occupied a low energy region as compared to the conventional X-ray crystal structure. Analysis of crystal packing indicates that the CCFS provides larger conformational space for the motions of the loop. CONCLUSIONS Our work reported the conformational ensemble of the loop in solution, which is in agreement with the structure obtained from CCFS approach. The combination of the experimental techniques and computational methods is beneficial for studying highly flexible regions of proteins. GENERAL SIGNIFICANCE Computational methods, such as loop modeling and MD simulations, have proved to be useful for studying conformational flexibility of proteins. These methods in integration with experimental techniques such as CCFS has the potential to transform the studies on flexible regions of proteins.
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Giani Tagliabue S, Faber SC, Motta S, Denison MS, Bonati L. Modeling the binding of diverse ligands within the Ah receptor ligand binding domain. Sci Rep 2019; 9:10693. [PMID: 31337850 PMCID: PMC6650409 DOI: 10.1038/s41598-019-47138-z] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 07/02/2019] [Indexed: 01/08/2023] Open
Abstract
The Ah receptor (AhR) is a ligand-dependent transcription factor belonging to the basic helix-loop-helix Per-Arnt-Sim (bHLH-PAS) superfamily. Binding to and activation of the AhR by a variety of chemicals results in the induction of expression of diverse genes and production of a broad spectrum of biological and toxic effects. The AhR also plays important roles in several physiological responses, which has led it to become a novel target for the development of therapeutic drugs. Differences in the interactions of various ligands within the AhR ligand binding domain (LBD) may contribute to differential modulation of AhR functionality. We combined computational and experimental analyses to investigate the binding modes of a group of chemicals representative of major classes of AhR ligands. On the basis of a novel computational approach for molecular docking to the homology model of the AhR LBD that includes the receptor flexibility, we predicted specific residues within the AhR binding cavity that play a critical role in binding of three distinct groups of chemicals. The prediction was validated by site-directed mutagenesis and evaluation of the relative ligand binding affinities for the mutant AhRs. These results provide an avenue for understanding ligand modulation of the AhR functionality and for rational drug design.
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Affiliation(s)
- Sara Giani Tagliabue
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milan, Italy
| | - Samantha C Faber
- Curriculum in Toxicology and Environmental Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Stefano Motta
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milan, Italy
| | - Michael S Denison
- Department of Environmental Toxicology, University of California, Davis, CA, USA
| | - Laura Bonati
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milan, Italy.
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13
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Faber SC, Soshilov AA, Giani Tagliabue S, Bonati L, Denison MS. Comparative In Vitro and In Silico Analysis of the Selectivity of Indirubin as a Human Ah Receptor Agonist. Int J Mol Sci 2018; 19:E2692. [PMID: 30201897 PMCID: PMC6165432 DOI: 10.3390/ijms19092692] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 09/06/2018] [Accepted: 09/06/2018] [Indexed: 12/11/2022] Open
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that modulates gene expression following its binding and activation by structurally diverse chemicals. Species differences in AhR functionality have been observed, with the mouse AhR (mAhR) and human AhR (hAhR) exhibiting significant differences in ligand binding, coactivator recruitment, gene expression and response. While the AhR agonist indirubin (IR) is a more potent activator of hAhR-dependent gene expression than the prototypical ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), it is a significantly less potent activator of the mAhR. DNA binding analysis confirmed the greater potency/efficacy of IR in stimulating transformation/DNA binding of the hAhR in vitro and domain-swapping experiments demonstrated that the enhanced response to IR was primarily due to the hAhR ligand binding domain (LBD). Site-directed mutagenesis and functional analysis studies revealed that mutation of H326 and A349 in the mAhR LBD to the corresponding residues in the hAhR LBD significantly increased the potency of IR. Since these mutations had no significant effect on ligand binding, these residues likely contribute to an enhanced efficiency of transformation/DNA binding by IR-bound hAhR. Molecular docking to mAhR LBD homology models further elucidated the different roles of the A375V mutation in TCDD and IR binding, as revealed by [³H]TCDD competitive binding results. These results demonstrate the differential binding of structurally diverse ligands within the LBD of a given AhR and confirm that amino acid differences within the LBD of AhRs contribute to significant species differences in ligand response.
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Affiliation(s)
- Samantha C Faber
- Department of Environmental Toxicology, University of California, Davis, CA 95616, USA.
| | - Anatoly A Soshilov
- Department of Environmental Toxicology, University of California, Davis, CA 95616, USA.
| | - Sara Giani Tagliabue
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milan 20126, Italy.
| | - Laura Bonati
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milan 20126, Italy.
| | - Michael S Denison
- Department of Environmental Toxicology, University of California, Davis, CA 95616, USA.
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14
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Motta S, Minici C, Corrada D, Bonati L, Pandini A. Ligand-induced perturbation of the HIF-2α:ARNT dimer dynamics. PLoS Comput Biol 2018; 14:e1006021. [PMID: 29489822 PMCID: PMC5847239 DOI: 10.1371/journal.pcbi.1006021] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 03/12/2018] [Accepted: 02/01/2018] [Indexed: 11/18/2022] Open
Abstract
Hypoxia inducible factors (HIFs) are transcription factors belonging to the basic helix−loop−helix PER-ARNT-SIM (bHLH-PAS) protein family with a role in sensing oxygen levels in the cell. Under hypoxia, the HIF-α degradation pathway is blocked and dimerization with the aryl hydrocarbon receptor nuclear translocator (ARNT) makes HIF-α transcriptionally active. Due to the common hypoxic environment of tumors, inhibition of this mechanism by destabilization of HIF-α:ARNT dimerization has been proposed as a promising therapeutic strategy. Following the discovery of a druggable cavity within the PAS-B domain of HIF-2α, research efforts have been directed to identify artificial ligands that can impair heterodimerization. Although the crystallographic structures of the HIF-2α:ARNT complex have elucidated the dimer architecture and the 0X3-inhibitor placement within the HIF-2α PAS-B, unveiling the inhibition mechanism requires investigation of how ligand-induced perturbations could dynamically propagate through the structure and affect dimerization. To this end, we compared evolutionary features, intrinsic dynamics and energetic properties of the dimerization interfaces of HIF-2α:ARNT in both the apo and holo forms. Residue conservation analysis highlighted inter-domain connecting elements that have a role in dimerization. Analysis of domain contributions to the dimerization energy demonstrated the importance of bHLH and PAS-A of both partners and of HIF-2α PAS-B domain in dimer stabilization. Among quaternary structure oscillations revealed by Molecular Dynamics simulations, the hinge-bending motion of the ARNT PAS-B domain around the flexible PAS-A/PAS-B linker supports a general model for ARNT dimerization in different heterodimers. Comparison of the HIF-2α:ARNT dynamics in the apo and 0X3-bound forms indicated a model of inhibition where the HIF-2α-PAS-B interfaces are destabilised as a result of water-bridged ligand-protein interactions and these local effects allosterically propagate to perturb the correlated motions of the domains and inter-domain communication. These findings will guide the design of improved inhibitors to contrast cell survival in tumor masses. A low oxygen condition, called hypoxia, often occurs in tumor masses and generally correlates with worse prognosis. Cells in a tumor react to low oxygen levels with a metabolism modification induced by the activation of hypoxia inducible factors (HIFs) through dimerization with a partner protein and binding to a DNA target. Disrupting this protein-protein interaction could be a potential therapeutic strategy, but directly interfering with dimer formation can be troublesome because of the difficulty to design drugs that bind to protein interfaces. However, ligands that bind internal protein cavities can indirectly perturb the interfaces reducing dimers stability. Albeit protein crystallography had offered a detailed static picture of a HIF dimer bound to candidate inhibitors, it is not able to describe either the perturbation caused by binding or the molecular mechanism of dimer destabilization. Here we exploit molecular dynamics to identify the crucial interfaces in the HIF dimer stabilization and, by comparing the results obtained in the bound and unbound forms, we reveal the mechanism of ligand inhibition at atomic detail. All these findings will guide toward the design of improved dimerization inhibitors, to contrast cell survival in tumor masses.
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Affiliation(s)
- Stefano Motta
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milan, Italy
| | - Claudia Minici
- Department of Immunology, Transplantation, and Infectious Diseases, DIBIT Fondazione San Raffaele, Milan, Italy
| | - Dario Corrada
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milan, Italy
| | - Laura Bonati
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milan, Italy
- * E-mail: (AP); (LB)
| | - Alessandro Pandini
- Department of Computer Science–Synthetic Biology Theme, Brunel University London, Uxbridge, United Kingdom
- The Thomas Young Centre for Theory and Simulation of Materials, London, United Kingdom
- * E-mail: (AP); (LB)
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Molecular modeling of the AhR structure and interactions can shed light on ligand-dependent activation and transformation mechanisms. CURRENT OPINION IN TOXICOLOGY 2017; 2:42-49. [PMID: 28497129 DOI: 10.1016/j.cotox.2017.01.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Molecular modeling has given important contributions to elucidation of the main stages in the AhR signal transduction pathway. Despite the lack of experimentally determined structures of the AhR functional domains, information derived from homologous systems has been exploited for modeling their structure and interactions. Homology models of the AhR PASB domain have provided information on the binding cavity and contributed to elucidate species-specific differences in ligand binding. Molecular Docking simulations of the ligand binding process have given insights into differences in binding of diverse agonists, antagonists, and selective AhR modulators, and their application to virtual screening of large databases of compounds have allowed identification of novel AhR ligands. Recently available structural information on protein-protein and protein-DNA complexes of other bHLH-PAS systems has opened the way for modeling the AhR:ARNT dimer structure and investigating the mechanisms of AhR transformation and DNA binding. Future research directions should include simulation of the protein dynamics to obtain a more reliable description of intermolecular interactions involved in signal transmission.
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