1
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Haidar R, Shabo R, Moeser M, Luch A, Kugler J. The nuclear entry of the aryl hydrocarbon receptor (AHR) relies on the first nuclear localization signal and can be negatively regulated through IMPα/β specific inhibitors. Sci Rep 2023; 13:19668. [PMID: 37951956 PMCID: PMC10640566 DOI: 10.1038/s41598-023-47066-z] [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: 05/23/2023] [Accepted: 11/08/2023] [Indexed: 11/14/2023] Open
Abstract
The human aryl hydrocarbon receptor (AHR) undergoes continuous shuttling between nucleus and cytoplasm. Binding to exogenous or endogenous ligands promotes its rapid nuclear import. The proposed mechanism for the ligand-dependent import is based on exposing the bipartite nuclear localisation signal (NLS) to members of the importin (IMP) superfamily. Among this, the molecular interactions involved in the basal import still need to be clarified. Utilizing fluorescently fused AHR variants, we recapitulated and characterized AHR localization and nucleo-cytoplasmic shuttling in living cells. Analysis of AHR variants carrying NLS point mutations demonstrated a mandatory role of first (13RKRRK17) and second (37KR-R40) NLS segments on the basal import of AHR. Further experiments indicated that ligand-induced import is mainly regulated through the first NLS, while the second NLS is supportive but not essential. Additionally, applying IMPα/β specific inhibitors, ivermectin (IVM) and importazole (IPZ), slowed down the ligand-induced import and, correspondingly, decreased the basal nuclear accumulation of the receptor. In conclusion, our data show that ligand-induced and basal nuclear entry of AHR rely on the same mechanism but are controlled uniquely by the two NLS components.
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Affiliation(s)
- Rashad Haidar
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany.
- Department of Biology, Chemistry and Pharmacy, Institute of Pharmacy, Freie Universität Berlin, Berlin, Germany.
| | - Reneh Shabo
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Marie Moeser
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Andreas Luch
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
- Department of Biology, Chemistry and Pharmacy, Institute of Pharmacy, Freie Universität Berlin, Berlin, Germany
| | - Josephine Kugler
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
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2
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Foxx CL, Nagy MR, King AE, Albin D, DeKrey GK. TCDD exposure alters fecal IgA concentrations in male and female mice. BMC Pharmacol Toxicol 2022; 23:25. [PMID: 35449084 PMCID: PMC9026712 DOI: 10.1186/s40360-022-00563-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 03/30/2022] [Indexed: 11/16/2022] Open
Abstract
Background Activation of the aryl hydrocarbon receptor (AhR) can alter diurnal rhythms including those for innate lymphoid cell numbers, cytokine and hormone levels, and feeding behaviors. Because immune responses and antibody levels are modulated by exposure to AhR agonists, we hypothesized that some of the variation previously reported for the effects of AhR activation on fecal secretory immunoglobulin A (sIgA) levels could be explained by dysregulation of the diurnal sIgA rhythm. Methods C57Bl/6 J mice were exposed to peanut oil or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 10 or 40 μg/Kg) and fecal sIgA levels were determined in samples collected every 4 h over 4 days. Results Fecal sIgA concentrations were not significantly different between light and dark phases of the photoperiod in either male or female mice, and there were no significant circadian rhythms observed, but TCDD exposure significantly altered both fecal mesor sIgA and serum IgA concentrations, in parallel, in male (increased) and female (biphasic) mice. Conclusions AhR activation can contribute to the regulation of steady state IgA/sIgA concentrations. Supplementary Information The online version contains supplementary material available at 10.1186/s40360-022-00563-9.
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Affiliation(s)
- Christine L Foxx
- School of Biological Sciences, College of Natural and Health Sciences, University of Northern Colorado, Greeley, CO, 80639, USA
| | - Madeline R Nagy
- School of Biological Sciences, College of Natural and Health Sciences, University of Northern Colorado, Greeley, CO, 80639, USA
| | - Aspen E King
- School of Biological Sciences, College of Natural and Health Sciences, University of Northern Colorado, Greeley, CO, 80639, USA
| | - Dreycey Albin
- Department of Computer Science, College of Engineering and Applied Science, University of Colorado, Boulder, 80309, CO, USA
| | - Gregory K DeKrey
- School of Biological Sciences, College of Natural and Health Sciences, University of Northern Colorado, Greeley, CO, 80639, USA.
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3
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Guarnieri T. Hypothesis: Emerging Roles for Aryl Hydrocarbon Receptor in Orchestrating CoV-2-Related Inflammation. Cells 2022; 11:cells11040648. [PMID: 35203299 PMCID: PMC8869960 DOI: 10.3390/cells11040648] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 02/09/2022] [Accepted: 02/10/2022] [Indexed: 02/05/2023] Open
Abstract
Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is the pathogenic agent of Coronavirus-Induced Disease-2019 (COVID-19), a multi-organ syndrome which primarily targets the respiratory system. In this review, considering the large amount of data pointing out the role of the Aryl hydrocarbon Receptor (AhR) in the inflammatory response and in the modulation of innate and adaptive immunity, we describe some mechanisms that strongly suggest its involvement in the management of COVID-19′s inflammatory framework. It regulates both the expression of Angiotensin Converting Enzyme-2 (ACE-2) and its stabilizing partner, the Broad neutral Amino acid Transporter 1 (B0AT1). It induces Indolamine 2,3 dioxygenase (IDO-1), the enzyme which, starting from Tryptophan (Trp), produces Kynurenine (Kyn, Beta-Anthraniloyl-L-Alanine). The accumulation of Kyn and the depletion of Trp arrest T cell growth and induce apoptosis, setting up an immune-tolerant condition, whereas AhR and interferon type I (IFN-I) build a mutual inhibitory loop that also involves NF-kB and limits the innate response. AhR/Kyn binding boosts the production of Interleukin-6 (IL-6), thus reinforcing the inflammatory state and counteracting the IDO-dependent immune tolerance in the later stage of COVID-19. Taken together, these data depict a framework where sufficient clues suggest the possible participation of AhR in the management of COVID-19 inflammation, thus indicating an additional therapeutic target for this disease.
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Affiliation(s)
- Tiziana Guarnieri
- Cell Physiology Laboratory, Department of Biological, Geological and Environmental Sciences (BiGeA), Alma Mater Studiorum Università di Bologna, 40126 Bologna, Italy;
- Interuniversity Consortium “Istituto Nazionale Biostrutture e Biosistemi” (INBB–Biostructures and Biosystems National Institute), 00136 Rome, Italy
- Interdepartmental Center for Industrial Research in Life Sciences and Technologies, University of Bologna, 40126 Bologna, Italy
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4
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Woo SJ. Molecular characterization of the aryl hydrocarbon receptor 2 gene in black rockfish, Sebastes schlegelii, and its expression patterns upon exposure to benzo[a]pyrene, 2,3,7,8-tetrachlorodibenzo-p-dioxin, and β-naphthoflavone. J Appl Toxicol 2021; 42:638-650. [PMID: 34651326 DOI: 10.1002/jat.4245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 09/05/2021] [Accepted: 09/13/2021] [Indexed: 11/09/2022]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates the toxicity of halogenated and polycyclic aromatic hydrocarbons in vertebrates. Thus, increased knowledge of AhR-mediated responses to xenobiotics is imperative. Sebastes schlegelii is increasingly being used as a model for studying environmental toxicology; hence, in this study, the presence of AhR2 was evaluated in S. schlegelii. The results showed that the predicted AhR2 amino acid sequence contained regions characteristic of other vertebrate AhRs, including the basic helix-loop-helix and PER-ARNT-SIM domains in the N-terminal half, but it had minor similarity with other vertebrate AhRs across the C-terminal half; it did not contain the distinct glutamine-rich domains found in mammalian AhR2. Phylogenetic analysis demonstrated that S. schlegelii AhR2 was clustered within the teleost AhR2 branch. Additionally, AhR2 mRNA was detectable in all 11 tissues tested, with the highest mRNA levels in the heart, pyloric ceca, and liver. Furthermore, exposure to the AhR agonists showed that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 1 μg/g body weight) induced a significantly higher increases in AhR2 expression in the gills, liver, kidneys, and spleen in 48 h than benzo[a]pyrene (2 μg/g body weight), and β-naphthoflavone (50-μg/g body weight); AhR2 mRNA levels upon TCDD exposure were up-regulated by 16- and 10-fold in the gills and liver, respectively. These findings indicated that AhR was a highly sensitive receptor against TCDD. Thus, investigating AhR2 expression in the presence of other xenobiotics might offer further information for the elucidation of its crucial role in mediating toxicant metabolism in S. schlegelii.
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Affiliation(s)
- Soo Ji Woo
- Department of Aquatic Life Medicine, Pukyong National University, Busan, South Korea.,Pathology Research Division, National Institute of Fisheries Science, Busan, South Korea
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5
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The role of DNA-binding and ARNT dimerization on the nucleo-cytoplasmic translocation of the aryl hydrocarbon receptor. Sci Rep 2021; 11:18194. [PMID: 34521881 PMCID: PMC8440571 DOI: 10.1038/s41598-021-97507-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 08/24/2021] [Indexed: 01/19/2023] Open
Abstract
The human aryl hydrocarbon receptor (AHR) is predominantly located in the cytoplasm, while activation depends on its nuclear translocation. Binding to endogenous or xenobiotic ligands terminates the basal nucleo-cytoplasmic shuttling and stabilizes an exclusive nuclear population. The precise mechanisms that facilitate such stable nuclear accumulation remain to be clarified as essential step in the activation cascade. In this study, we have tested whether the sustained nuclear compartmentalization of ligand-bound or basal AHR might further require heterodimerization with the AHR-nuclear translocator (ARNT) and binding to the cognate XRE-motif. Mutagenesis of the DNA-binding motif or of selected individual residues in the ARNT-binding motif did not lead to any variation in AHR’s nucleo-cytoplasmic distribution. In response to ligands, all mutants were retained in the nucleus demonstrating that the stable compartmentalization of activated AHR in the nucleus is neither dependent on interactions with DNA, nor ARNT. Knocking down the ARNT gene using small interfering RNA confirmed that ARNT does not play any role in the intracellular trafficking of AHR.
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6
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Roles of the ubiquitin ligase CUL4B and ADP-ribosyltransferase TiPARP in TCDD-induced nuclear export and proteasomal degradation of the transcription factor AHR. J Biol Chem 2021; 297:100886. [PMID: 34146543 PMCID: PMC8318916 DOI: 10.1016/j.jbc.2021.100886] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/08/2021] [Accepted: 06/15/2021] [Indexed: 12/14/2022] Open
Abstract
The aryl hydrocarbon receptor (AHR) is a transcription factor activated by exogenous halogenated polycyclic aromatic hydrocarbon compounds, including the environmental toxin TCDD, 2,3,7,8-tetrachlorodibenzo-p-dioxin, and naturally occurring dietary and endogenous compounds. The activated AHR enhances transcription of specific genes including phase I and phase II metabolism enzymes and other targets genes such as the TCDD-inducible poly(ADP-ribose) polymerase (TiPARP). The regulation of AHR activation is a dynamic process: immediately after transcriptional activation of the AHR by TCDD, the AHR is exported from the nucleus to the cytoplasm where it is subjected to proteasomal degradation. However, the mechanisms regulating AHR degradation are not well understood. Here, we studied the role of two enzymes reported to enhance AHR breakdown: the cullin 4B (CUL4B)AHR complex, an E3 ubiquitin ligase that targets the AHR and other proteins for ubiquitination, and TiPARP, which targets proteins for ADP-ribosylation, a posttranslational modification that can increase susceptibility to degradation. Using a WT mouse embryonic fibroblast (MEF) cell line and an MEF cell line in which CUL4B has been deleted (MEFCul4b-null), we discovered that loss of CUL4B partially prevented AHR degradation after TCDD exposure, while knocking down TiPARP in MEFCul4b-null cells completely abolished AHR degradation upon TCDD treatment. Increased TCDD-activated AHR protein levels in MEFCul4b-null and MEFCul4b-null cells in which TiPARP was knocked down led to enhanced AHR transcriptional activity, indicating that CUL4B and TiPARP restrain AHR action. This study reveals a novel function of TiPARP in controlling TCDD-activated AHR nuclear export and subsequent proteasomal degradation.
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7
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Borovok N, Weiss C, Sharkia R, Reichenstein M, Wissinger B, Azem A, Mahajnah M. Gene and Protein Expression in Subjects With a Nystagmus-Associated AHR Mutation. Front Genet 2020; 11:582796. [PMID: 33193710 PMCID: PMC7542227 DOI: 10.3389/fgene.2020.582796] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 09/02/2020] [Indexed: 11/24/2022] Open
Abstract
Recently, a consanguineous family was identified in Israel with three children affected by Infantile Nystagmus and Foveal Hypoplasia, following an autosomal recessive mode of inheritance. A homozygous stop mutation c.1861C > T; p.Q621∗ in the aryl hydrocarbon receptor (AHR) gene (AHR; MIM 600253) was identified that co-segregated with the disease in the larger family. AHR is the first gene to be identified causing an autosomal recessive Infantile Nystagmus-related disease in humans. The goal of this study is to delineate the molecular basis of this newly discovered human genetic disorder associated with a rare AHR gene mutation. The gene and protein expression levels of AHR and selected AHR targets from leukocyte cultures of healthy subjects and the patients were analyzed. We observed significant variation between mRNA and protein expression of CYP1A1, CYP1B1, and TiPARP under rest and AHR-induced conditions. The CYP1A1 enzymatic activity in induced leukocytes also differs significantly between the patients and healthy volunteers. Intriguingly, the heterozygous subjects demonstrate CYP1A1 and TiPARP gene and protein expression similar to homozygous patients. In contrast, CYP1B1 inducibility and expression vary between hetero- and homozygous subjects. Similarity and differences in gene and protein expression between heterozygotes and homozygous patients can give us a hint as to which metabolic pathway/s might be involved in the Nystagmus etiology. Thus, we have a unique human model for AHR deficiency that will allow us the opportunity to study the biochemical basis of this rare human mutation, as well as the involvement of AHR in other physiological processes.
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Affiliation(s)
- Natalia Borovok
- Faculty of Life Sciences, School of Neurobiology, Biochemistry and Biophysics, Tel Aviv University, Tel Aviv, Israel
| | - Celeste Weiss
- Faculty of Life Sciences, School of Neurobiology, Biochemistry and Biophysics, Tel Aviv University, Tel Aviv, Israel
| | - Rajech Sharkia
- Triangle Research and Development Center, Kafr Qara, Israel.,Beit Berl College, Beit Berl, Israel
| | - Michal Reichenstein
- Faculty of Life Sciences, School of Neurobiology, Biochemistry and Biophysics, Tel Aviv University, Tel Aviv, Israel
| | - Bernd Wissinger
- Institute for Ophthalmic Research Centre for Ophthalmology, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Abdussalam Azem
- Faculty of Life Sciences, School of Neurobiology, Biochemistry and Biophysics, Tel Aviv University, Tel Aviv, Israel
| | - Muhammad Mahajnah
- Hillel Yaffe Medical Center, Hadera, Israel.,The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
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8
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Hayashi A, Denison MS. Development of a novel recombinant cell line for detection and characterization of Ah receptor nuclear translocation in intact cells. Toxicol In Vitro 2020; 66:104873. [PMID: 32333947 DOI: 10.1016/j.tiv.2020.104873] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 04/04/2020] [Accepted: 04/22/2020] [Indexed: 02/04/2023]
Abstract
The Ah receptor (AhR) is a ligand-dependent transcriptional factor that mediates the effects of structurally diverse chemicals. Ligand binding stimulates nuclear translocation of the AhR and leads to AhR DNA binding and increased gene expression. Studies of the molecular mechanisms by which ligands bind to and activate the AhR and AhR-dependent signal transduction require methods to easily examine each step of the AhR signaling pathway. While current assays can measure ligand and DNA binding in vitro and gene expression in cells, there is no simple method to monitor AhR nuclear translocation. We developed a stably transfected mouse hepatoma cell line (yAHAYc6) that expresses yellow fluorescent protein-tagged AhR (yAhR) for use in qualitative or semiquantitative assessment of nuclear/cytoplasmic distribution of yAhR in living cells by fluorescent microscopy. yAhR nuclear translocation was stimulated in a concentration- and time-dependent manner by AhR agonists and inhibited by antagonists. Inhibition of nuclear export channels by leptomycin B, resulted in increased nuclear accumulation of yAhR in the absence of added ligand, indicating endogenous nucleocytoplasmic shuttling of unliganded AhR and demonstrating the utility of these cells. This novel cell line can be used to detect and characterize AhR ligands and will facilitate mechanistic studies of AhR signaling.
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Affiliation(s)
- Ai Hayashi
- Department of Environmental Toxicology, University of California, Davis, CA 95616, USA
| | - Michael S Denison
- Department of Environmental Toxicology, University of California, Davis, CA 95616, USA.
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9
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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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10
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Mayer AK, Mahajnah M, Thomas MG, Cohen Y, Habib A, Schulze M, Maconachie GDE, AlMoallem B, De Baere E, Lorenz B, Traboulsi EI, Kohl S, Azem A, Bauer P, Gottlob I, Sharkia R, Wissinger B. Homozygous stop mutation in AHR causes autosomal recessive foveal hypoplasia and infantile nystagmus. Brain 2020; 142:1528-1534. [PMID: 31009037 DOI: 10.1093/brain/awz098] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 02/04/2019] [Accepted: 02/16/2019] [Indexed: 01/27/2023] Open
Abstract
Herein we present a consanguineous family with three children affected by foveal hypoplasia with infantile nystagmus, following an autosomal recessive mode of inheritance. The patients showed normal electroretinography responses, no signs of albinism, and no anterior segment or brain abnormalities. Upon whole exome sequencing, we identified a homozygous mutation (c.1861C>T;p.Q621*) in the aryl hydrocarbon receptor (AHR) gene that perfectly co-segregated with the disease in the larger family. AHR is a ligand-activated transcription factor that has been intensively studied in xenobiotic-induced toxicity. Further, it has been shown to play a physiological role under normal cellular conditions, such as in immunity, inflammatory response and neurogenesis. Notably, knockout of the Ahr gene in mouse impairs optic nerve myelin sheath formation and results in oculomotor deficits sharing many features with our patients: the eye movement disorder in Ahr-/- mice appears early in development and presents as conjugate horizontal pendular nystagmus. We therefore propose AHR to be a novel disease gene for a new, recessively inherited disorder in humans, characterized by infantile nystagmus and foveal hypoplasia.
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Affiliation(s)
- Anja K Mayer
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Muhammad Mahajnah
- Child Neurology and Development Center, Hillel-Yaffe Medical Center, Hadera, Israel.,The Ruth and Bruce Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Mervyn G Thomas
- Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, UK
| | - Yuval Cohen
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion, Haifa, Israel.,Ophthalmology Department, Hillel Yaffe Medical Center, Hadera, Israel
| | - Adib Habib
- Pediatric Department, St. Vincent French Hospital, Nazareth, Israel
| | - Martin Schulze
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
| | - Gail D E Maconachie
- Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, UK
| | - Basamat AlMoallem
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium.,Department of Ophthalmology, King Abdul-Aziz University Hospital, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Elfride De Baere
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Birgit Lorenz
- Department of Ophthalmology, Justus Liebig University Giessen, Giessen, Germany
| | | | - Susanne Kohl
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Abdussalam Azem
- Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel Aviv, Israel
| | - Peter Bauer
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
| | - Irene Gottlob
- Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, UK
| | - Rajech Sharkia
- The Triangle Regional Research and Development Center, Kfar Qari', Israel.,Beit-Berl Academic College, Beit-Berl, Israel
| | - Bernd Wissinger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
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11
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Subcellular Localization Signals of bHLH-PAS Proteins: Their Significance, Current State of Knowledge and Future Perspectives. Int J Mol Sci 2019; 20:ijms20194746. [PMID: 31554340 PMCID: PMC6801399 DOI: 10.3390/ijms20194746] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 09/22/2019] [Accepted: 09/23/2019] [Indexed: 12/14/2022] Open
Abstract
The bHLH-PAS (basic helix-loop-helix/ Period-ARNT-Single minded) proteins are a family of transcriptional regulators commonly occurring in living organisms. bHLH-PAS members act as intracellular and extracellular "signals" sensors, initiating response to endo- and exogenous signals, including toxins, redox potential, and light. The activity of these proteins as transcription factors depends on nucleocytoplasmic shuttling: the signal received in the cytoplasm has to be transduced, via translocation, to the nucleus. It leads to the activation of transcription of particular genes and determines the cell response to different stimuli. In this review, we aim to present the current state of knowledge concerning signals that affect shuttling of bHLH-PAS transcription factors. We summarize experimentally verified and published nuclear localization signals/nuclear export signals (NLSs/NESs) in the context of performed in silico predictions. We have used most of the available NLS/NES predictors. Importantly, all our results confirm the existence of a complex system responsible for protein localization regulation that involves many localization signals, which activity has to be precisely controlled. We conclude that the current stage of knowledge in this area is still not complete and for most of bHLH-PAS proteins an experimental verification of the activity of further NLS/NES is needed.
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12
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Fujisawa N, Yoshioka W, Yanagisawa H, Tohyama C. Significance of AHR nuclear translocation sequence in 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced cPLA 2α activation and hydronephrosis. Arch Toxicol 2019; 93:1255-1264. [PMID: 30790002 DOI: 10.1007/s00204-019-02414-9] [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: 09/13/2018] [Accepted: 02/14/2019] [Indexed: 12/13/2022]
Abstract
The aryl hydrocarbon receptor (AHR) plays a major role in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced toxicity phenotypes. TCDD bound to AHR elicits both genomic action in which target genes are transcriptionally upregulated and nongenomic action in which cytosolic phospholipase A2α (cPLA2α) is rapidly activated. However, how either of these actions, separately or in combination, induces toxicity phenotypes is largely unknown. In this study, we used AHRnls/nls mice as a model in which AHR was mutated to lack nuclear translocation sequence (NLS), and AHRd/- mice as the corresponding control. Using this model, we studied TCDD-induced alterations in cPLA2α activation and related factors because of the pivotal roles of cPLA2α both in AHR's nongenomic action and in regulation of causative genes of TCDD-induced hydronephrosis. Dams were orally administered TCDD at a dose of 300 µg/kg body weight on postnatal day 1, and pups subsequently exposed to TCDD via milk were examined for gene expression on PND 7 and for histological changes on PND 14. The activation of the AHR genomic action and hydronephrosis onset were observed in the control group but not in the AHRnls/nls group. An ex vivo experiment using peritoneal macrophages exposed to 100 nM TCDD resulted in rapid activation of cPLA2α, an indicator of the nongenomic action, only in the control group but not in the AHRnls/nls group. These results indicated that an NLS is required for the AHR's genomic and nongenomic actions.
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Affiliation(s)
- Nozomi Fujisawa
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Wataru Yoshioka
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan. .,Department of Public Health and Environmental Medicine, The Jikei University School of Medicine, Tokyo, 105-8461, Japan.
| | - Hiroyuki Yanagisawa
- Department of Public Health and Environmental Medicine, The Jikei University School of Medicine, Tokyo, 105-8461, Japan
| | - Chiharu Tohyama
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan. .,Faculty of Medicine, University of Tsukuba, Tsukuba, 305-8575, Japan.
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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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Lewis HC, Chinnadurai R, Bosinger SE, Galipeau J. The IDO inhibitor 1-methyl tryptophan activates the aryl hydrocarbon receptor response in mesenchymal stromal cells. Oncotarget 2017; 8:91914-91927. [PMID: 29190885 PMCID: PMC5696151 DOI: 10.18632/oncotarget.20166] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 07/02/2017] [Indexed: 01/15/2023] Open
Abstract
The catabolism of tryptophan (Trp) by indoleamine 2,3-dioxygenase (IDO) is a key step in tolerance effected by a variety of cell types, including mesenchymal stromal cells (MSCs). Trp catabolism generates molecules known as kynurenines, whose tolerance mechanisms involve activation of the Aryl Hydrocarbon Receptor (AHR). A synthetic analog of Trp, 1-methyl tryptophan (1MT), is a selective inhibitor of IDO enzymatic activity being utilized in cancer immunotherapy trials. We hypothesized 1MT might activate AHR independently of its effects on IDO. We demonstrate MSCs express AHR protein, and that in vitro treatment with 1MT causes AHR nucleotranslocation. Upon analyzing mRNA, we observed transcriptional upregulation of cytochrome p450 1a1 and 1b1 by 1MT racemic mixture (R-MT), consistent with AHR-activation. RNA-sequencing identified Nrf2, MAPK12 and IL-1a as downstream targets of 1MT. We demonstrate 1a1 and 1b1 activation by 1MT in IDO+ MSC following interferon-γ (IFN-γ) activation, suggesting AHR signaling is uncoupled from IDO catalytic function. Such a mechanism of action for 1MT may extend its usage to a wider range of patients, irrespective of tumor IDO expression. These observations support a novel paradigm by which AHR-activating compounds like 1MT can be used in cancer immunotherapy to stimulate a pro-inflammatory response.
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Affiliation(s)
- Holly C. Lewis
- Departments of Pediatrics and Hematology & Medical Oncology, Emory University School of Medicine, Atlanta, GA, USA
| | - Raghavan Chinnadurai
- Department of Medicine and University of Wisconsin Carbone Cancer Center, University of Wisconsin in Madison, Madison, WI, USA
| | - Steven E. Bosinger
- Department of Pathology & Laboratory Medicine, Emory University, Atlanta, GA, USA
- Yerkes NHP Genomics Core Laboratory, Div. Microbiology & Immunology, Yerkes National Primate Research Center, Atlanta, GA, USA
| | - Jacques Galipeau
- Department of Medicine and University of Wisconsin Carbone Cancer Center, University of Wisconsin in Madison, Madison, WI, USA
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