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Gutierrez F, Murphy QM, Swartwout BK, Read KA, Edwards MR, Abdelhamid L, Cabana-Puig X, Testerman JC, Xu T, Lu R, Amin P, Cecere TE, Reilly CM, Oestreich KJ, Ciupe SM, Luo XM. TCDD and CH223191 Alter T Cell Balance but Fail to Induce Anti-Inflammatory Response in Adult Lupus Mice. Immunohorizons 2024; 8:172-181. [PMID: 38353996 PMCID: PMC10916358 DOI: 10.4049/immunohorizons.2300023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 01/16/2024] [Indexed: 02/16/2024] Open
Abstract
Aryl hydrocarbon receptor (AhR) responds to endogenous and exogenous ligands as a cytosolic receptor, transcription factor, and E3 ubiquitin ligase. Several studies support an anti-inflammatory effect of AhR activation. However, exposure to the AhR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during early stages of development results in an autoimmune phenotype and exacerbates lupus. The effects of TCDD on lupus in adults with pre-existing autoimmunity have not been described. We present novel evidence that AhR stimulation by TCDD alters T cell responses but fails to impact lupus-like disease using an adult mouse model. Interestingly, AhR antagonist CH223191 also changed T cell balance in our model. We next developed a conceptual framework for identifying cellular and molecular factors that contribute to physiological outcomes in lupus and created models that describe cytokine dynamics that were fed into a system of differential equations to predict the kinetics of T follicular helper (Tfh) and regulatory T (Treg) cell populations. The model predicted that Tfh cells expanded to larger values following TCDD exposure compared with vehicle and CH223191. Following the initial elevation, both Tfh and Treg cell populations continuously decayed over time. A function based on the ratio of predicted Treg/Tfh cells showed that Treg cells exceed Tfh cells in all groups, with TCDD and CH223191 showing lower Treg/Tfh cell ratios than the vehicle and that the ratio is relatively constant over time. We conclude that AhR ligands did not induce an anti-inflammatory response to attenuate autoimmunity in adult lupus mice. This study challenges the dogma that TCDD supports an immunosuppressive phenotype.
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Affiliation(s)
- Fernando Gutierrez
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - Quiyana M. Murphy
- Department of Mathematics, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - Brianna K. Swartwout
- Translational Biology Medicine and Health Graduate Program, Virginia Polytechnic Institute and State University, Roanoke, VA
| | - Kaitlin A. Read
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - Michael R. Edwards
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - Leila Abdelhamid
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - Xavier Cabana-Puig
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - James C. Testerman
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - Tian Xu
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - Ran Lu
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - Pavly Amin
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - Thomas E. Cecere
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - Christopher M. Reilly
- Department of Biomedical Sciences, Edward Via College of Osteopathic Medicine, Blacksburg, VA
| | - Kenneth J. Oestreich
- Department of Microbial Infection and Immunity, Ohio State University College of Medicine, Columbus, OH
| | - Stanca M. Ciupe
- Department of Mathematics, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - Xin M. Luo
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA
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Emerging roles of hnRNP A2B1 in cancer and inflammation. Int J Biol Macromol 2022; 221:1077-1092. [PMID: 36113587 DOI: 10.1016/j.ijbiomac.2022.09.104] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 08/27/2022] [Accepted: 09/11/2022] [Indexed: 11/05/2022]
Abstract
Heterogeneous nuclear ribonucleoproteins (hnRNPs) are a group of RNA-binding proteins with important roles in multiple aspects of nucleic acid metabolism, including the packaging of nascent transcripts, alternative splicing, transactivation of gene expression, and regulation of protein translation. As a core component of the hnRNP complex in mammalian cells, heterogeneous nuclear ribonucleoprotein A2B1 (hnRNP A2B1) participates in and coordinates various molecular events. Given its regulatory role in inflammation and cancer progression, hnRNP A2B1 has become a novel player in immune response, inflammation, and cancer development. Concomitant with these new roles, a surprising number of mechanisms deemed to regulate hnRNP A2B1 functions have been identified, including post-translational modifications, changes in subcellular localization, direct interactions with multiple DNAs, RNAs, and proteins or the formation of complexes with them, which have gradually made hnRNP A2B1 a molecular target for multiple drugs. In light of the rising interest in the intersection between cancer and inflammation, this review will focus on recent knowledge of the biological roles of hnRNP A2B1 in cancer, immune response, and inflammation.
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Rannug A. 6-Formylindolo[3,2-b]carbazole, a Potent Ligand for the Aryl Hydrocarbon Receptor Produced Both Endogenously and by Microorganisms, can Either Promote or Restrain Inflammatory Responses. FRONTIERS IN TOXICOLOGY 2022; 4:775010. [PMID: 35295226 PMCID: PMC8915874 DOI: 10.3389/ftox.2022.775010] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 01/11/2022] [Indexed: 12/13/2022] Open
Abstract
The aryl hydrocarbon receptor (AHR) binds major physiological modifiers of the immune system. The endogenous 6-formylindolo[3,2-b]carbazole (FICZ), which binds with higher affinity than any other compound yet tested, including TCDD, plays a well-documented role in maintaining the homeostasis of the intestines and skin. The effects of transient activation of AHR by FICZ differ from those associated with continuous stimulation and, depending on the dose, include either differentiation into T helper 17 cells that express proinflammatory cytokines or into regulatory T cells or macrophages with anti-inflammatory properties. Moreover, in experimental models of human diseases high doses stimulate the production of immunosuppressive cytokines and suppress pathogenic autoimmunity. In our earlier studies we characterized the formation of FICZ from tryptophan via the precursor molecules indole-3-pyruvate and indole-3-acetaldehyde. In the gut formation of these precursor molecules is catalyzed by microbial aromatic-amino-acid transaminase ArAT. Interestingly, tryptophan can also be converted into indole-3-pyruvate by the amino-acid catabolizing enzyme interleukin-4 induced gene 1 (IL4I1), which is secreted by host immune cells. By thus generating derivatives of tryptophan that activate AHR, IL4I1 may have a role to play in anti-inflammatory responses, as well as in a tumor escape mechanism that reduces survival in cancer patients. The realization that FICZ can be produced from tryptophan by sunlight, by enzymes expressed in our cells (IL4I1), and by microorganisms as well makes it highly likely that this compound is ubiquitous in humans. A diurnal oscillation in the level of FICZ that depends on the production by the fluctuating number of microbes might influence not only intestinal and dermal immunity locally, but also systemic immunity.
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Hwang JH, Kannan K, Evans TJ, Iwata H, Kim EY. Assessment of Risks of Dioxins for Aryl Hydrocarbon Receptor-Mediated Effects in Polar Bear ( Ursus maritimus) by in Vitro and in Silico Approaches. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:1770-1781. [PMID: 31841312 DOI: 10.1021/acs.est.9b05941] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Polar bear (Ursus maritimus) populations accumulate dioxins and related compounds (DRCs) at levels that are of health concern. The toxicities of DRCs are primarily mediated via aryl hydrocarbon receptor (AHR) signaling pathway. To evaluate the sensitivity and responses to DRCs in polar bears, we assessed the activation potencies of polar bear-specific AHR (pbAHR) by DRCs through in vitro and in silico approaches. In vitro assays showed that the pbAHR was as sensitive to DRCs as C3H/lpr mouse AHR, which is well-known to be highly sensitive to DRCs. Comparison of pbAHR transactivation potencies indicated that TCDF, 2,3,4,7,8-PeCDF, and BaP exhibited high induction equivalency factors (IEFs). Considering the accumulation levels of DRCs in polar bears, PCB126 was found to be the most active inducer of pbAHR. The in vitro transactivation potencies of ligands of pbAHR showed a significant relationship with in silico ligand docking energies in a pbAHR homology model. The protein ligand interaction fingerprint (PLIF) analysis showed different interaction patterns depending on the ligands. Several amino acids which are highly conserved among mammals may be involved in species-specific responses via backbone interactions with neighboring amino acid residues which are specific to pbAHR. We document high susceptibility of polar bears to DRCs, through a mechanistic approach, for the first time.
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Affiliation(s)
- Ji-Hee Hwang
- Department of Life and Nanopharmaceutical Science and Department of Biology , Kyung Hee University , Seoul 130-701 , Korea
| | - Kurunthachalam Kannan
- Wadsworth Center , New York State Department of Health, Empire State Plaza , P.O. Box 509, Albany , New York 12201-0509 , United States
| | - Thomas J Evans
- United States Fish and Wildlife Service , Office of Subsistence Management , Anchorage , Alaska 99503 , United States
| | - 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 , Seoul 130-701 , Korea
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Bak SM, Nakata H, Koh DH, Yoo J, Iwata H, Kim EY. In vitro and in silico AHR assays for assessing the risk of heavy oil-derived polycyclic aromatic hydrocarbons in fish. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 181:214-223. [PMID: 31195230 DOI: 10.1016/j.ecoenv.2019.06.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 05/31/2019] [Accepted: 06/02/2019] [Indexed: 06/09/2023]
Abstract
In the aftermath of the Great East Japan Earthquake of March 11, 2011, marine fish in Kesennuma Bay, Japan, have been contaminated with heavy oil containing polycyclic aromatic hydrocarbons (PAHs). To estimate the risk of six PAHs (benzo[α]pyrene, dibenzothiophene, phenanthrene, 2,3,5-trimethylnaphthalene, acenaphthene, and 1-methylphenanthrene), which have been detected at high levels in the tissues of fish from Kesennuma Bay, we attempted to evaluate the effects of these PAHs on the fish aryl hydrocarbon receptor (AHR) signaling pathway. We initially measured PAH concentrations and cytochrome P4501A catalytic activities (EROD: ethoxyresorufin-O-deethylase and MROD: methoxyresorufin-O-demethylase) as markers of AHR activation in greenlings (Hexagrammos otakii) collected from Kesennuma Bay in 2014. The results showed that alkylated PAH concentrations and EROD/MROD activities were higher in sites close to the oil-spilled sites than in the control site, suggesting AHR activation by spilled alkylated PAHs. We then investigated AHR-mediated responses to these PAHs in the in vitro reporter gene assay system where red seabream (Pagrus major) AHR1 (rsAHR1) or rsAHR2 expression plasmids were transiently transfected into COS-7 cells. The in vitro assay showed rsAHR isoform-, PAH-, and dose-dependent transactivation potencies. The relative effective concentrations of benzo[α]pyrene, dibenzothiophene, phenanthrene, 2,3,5-trimethylnaphthalene, acenaphthene, and 1-methylphenanthrene that induce 20% of the maximum benzo[α]pyrene response (REC20-BaP) for rsAHR1 activation were 0.052, 38, 79, 88, 270 nM, and no response, respectively, and those for rsAHR2 activation were 0.0049, 32, 53, 88, 60 nM, and no response, respectively. The results showed that the REC20-BaP values of benzo[α]pyrene for both the rsAHR1 and rsAHR2 isoforms were lower than the concentrations (0.041-0.20 nM) detected in the muscle tissue of fish from Kesennuma Bay, while the REC20-BaP values of other PAHs were higher than their tissue concentrations. In silico rsAHR homology modeling and subsequent ligand docking simulation analyses indicated that the rsAHR activation potencies of PAHs could be predicted from a rsAHR2 model. This study shows that in vitro and in silico rsAHR analyses may be a useful tool for assessing the risks to fish contaminated with PAHs.
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Affiliation(s)
- Su-Min Bak
- Laboratory of Environmental Toxicology, Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matsuyama, 790-8577, Japan.
| | - Haruhiko Nakata
- Faculty of the Advanced Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto, 860-8555, Japan.
| | - Dong-Hee Koh
- Department of Life and Nanopharmaceutical Science, Kyung Hee University,26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea.
| | - Jean Yoo
- Laboratory of Environmental Toxicology, Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matsuyama, 790-8577, Japan.
| | - Hisato Iwata
- Laboratory of Environmental Toxicology, Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matsuyama, 790-8577, Japan.
| | - Eun-Young Kim
- Department of Life and Nanopharmaceutical Science, Kyung Hee University,26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea; Department of Biology, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea.
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Rannug A, Rannug U. The tryptophan derivative 6-formylindolo[3,2-b]carbazole, FICZ, a dynamic mediator of endogenous aryl hydrocarbon receptor signaling, balances cell growth and differentiation. Crit Rev Toxicol 2018; 48:555-574. [PMID: 30226107 DOI: 10.1080/10408444.2018.1493086] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The aryl hydrocarbon receptor (AHR) is not essential to survival, but does act as a key regulator of many normal physiological events. The role of this receptor in toxicological processes has been studied extensively, primarily employing the high-affinity ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). However, regulation of physiological responses by endogenous AHR ligands remains to be elucidated. Here, we review developments in this field, with a focus on 6-formylindolo[3,2-b]carbazole (FICZ), the endogenous ligand with the highest affinity to the receptor reported to date. The binding of FICZ to different isoforms of the AHR seems to be evolutionarily well conserved and there is a feedback loop that controls AHR activity through metabolic degradation of FICZ via the highly inducible cytochrome P450 1A1. Several investigations provide strong evidence that FICZ plays a critical role in normal physiological processes and can ameliorate immune diseases with remarkable efficiency. Low levels of FICZ are pro-inflammatory, providing resistance to pathogenic bacteria, stimulating the anti-tumor functions, and promoting the differentiation of cancer cells by repressing genes in cancer stem cells. In contrast, at high concentrations FICZ behaves in a manner similar to TCDD, exhibiting toxicity toward fish and bird embryos, immune suppression, and activation of cancer progression. The findings are indicative of a dual role for endogenously activated AHR in barrier tissues, aiding clearance of infections and suppressing immunity to terminate a vicious cycle that might otherwise lead to disease. There is not much support for the AHR ligand-specific immune responses proposed, the differences between FICZ and TCDD in this context appear to be explained by the rapid metabolism of FICZ.
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Affiliation(s)
- Agneta Rannug
- a Karolinska Institutet, Institute of Environmental Medicine , Stockholm , Sweden
| | - Ulf Rannug
- b Department of Molecular Biosciences , The Wenner-Gren Institute, Stockholm University , Stockholm , Sweden
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Yuan X, Dou Y, Wu X, Wei Z, Dai Y. Tetrandrine, an agonist of aryl hydrocarbon receptor, reciprocally modulates the activities of STAT3 and STAT5 to suppress Th17 cell differentiation. J Cell Mol Med 2017; 21:2172-2183. [PMID: 28332288 PMCID: PMC5571555 DOI: 10.1111/jcmm.13141] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 12/25/2016] [Indexed: 01/05/2023] Open
Abstract
Tetrandrine, a bisbenzylisoquinoline alkaloid constituent of the root of Stephania tetrandra S. Moore, was previously shown to suppress the differentiation of T helper 17 (Th17) cells and consequently ameliorate the collagen‐induced arthritis (CIA) in mice by activating the aryl hydrocarbon receptor (AhR), but its underlying mechanism is incompletely understood. Here, we investigated how tetrandrine suppressed Th17 cell differentiation through the AhR pathway. The naïve CD4+ T cells were stimulated with anti‐CD3/CD28 for 72 hrs in the presence or absence of tetrandrine under the Th17‐polarizing condition. Tetrandrine inhibited the phosphorylation of signal transducer and activator of transcription‐3 (STAT3) and boosted the phosphorylation of STAT5, while it did not alter the expression levels of phospho‐Janus kinase‐1 (p‐JAK1), p‐JAK2, p‐JAK3, and suppressor of cytokine signalling‐3 (SOCS3). The tetrandrine‐mediated inhibition of the Th17 cell differentiation could be diminished by the activator of STAT3 and the inhibitor of STAT5. Meanwhile, the effect of tetrandrine on the either STAT3 or STAT5 phosphorylation was almost completely reversed by the AhR antagonist CH223191 and the AhR knockdown. In CIA mice, tetrandrine decreased p‐STAT3 levels and increased p‐STAT5 levels, which could also be reversed by the AhR antagonist resveratrol administration. Furthermore, tetrandrine promoted the AhR binding to the STAT5, but not to the STAT3. The tetrandrine‐induced inhibition of the STAT3 phosphorylation was diminished by the inhibitor of STAT5. Taken together, tetrandrine suppressed Th17 cell differentiation by reciprocally modulating the activities of STAT3 and STAT5 in an AhR‐dependent manner.
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Affiliation(s)
- Xusheng Yuan
- Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, China
| | - Yannong Dou
- Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, China
| | - Xin Wu
- Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, China
| | - Zhifeng Wei
- Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, China
| | - Yue Dai
- Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, China
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Nguyen HT, Tsuchiya MCL, Yoo J, Iida M, Agusa T, Hirano M, Kim EY, Miyazaki T, Nose M, Iwata H. Strain differences in the proteome of dioxin-sensitive and dioxin-resistant mice treated with 2,3,7,8-tetrabromodibenzo-p-dioxin. Arch Toxicol 2016; 91:1763-1782. [PMID: 27604104 DOI: 10.1007/s00204-016-1834-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 08/24/2016] [Indexed: 11/28/2022]
Abstract
Dioxins cause various toxic effects through the aryl hydrocarbon receptor (AHR) in vertebrates, with dramatic species and strain differences in susceptibility. Although inbred mouse strains C3H/HeJ-lpr/lpr (C3H/lpr) and MRL/MpJ-lpr/lpr (MRL/lpr) are known as dioxin-sensitive and dioxin-resistant mice, respectively, the molecular mechanism underlying this difference remains unclear. The difference in the hepatic proteome of the two mouse strains treated with vehicle or 2,3,7,8-tetrabromodibenzo-p-dioxin (TBDD) was investigated by a proteomic approach of two-dimensional electrophoresis (2-DE) coupled with matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectrometry (MALDI-TOF/TOF). To confirm the strain-difference in response to TBDD treatment, cytochrome P450 (CYP) 1A1 and 1A2 protein levels were measured in both strains. A dose of 10 µg/kg body weight of TBDD induced hepatic CYP1A1 and CYP1A2 expression in both strains, but the expression levels of both CYP1A proteins were higher in C3H/lpr mice than in MRL/lpr mice, supporting that C3H/lpr mice are more sensitive to dioxins than MRL/lpr mice. Proteins that were more induced or suppressed by TBDD treatment in C3H/lpr mice were successfully identified by 2-DE and MALDI-TOF/TOF, including proteins responsible for AHR activation through production of endogenous ligands such as aspartate aminotransferase, indolethylamine N-methyltransferase, and aldehyde dehydrogenases, as well as proteins reducing oxidative stress, such as superoxide dismutase and peroxiredoxins. Taken together, our results provide insights into the molecular mechanism underlying the high dioxin susceptibility of the C3H/lpr strain, in which AHR activation by TBDD is more prompted by the production of endogenous ligands, but the adaptation to oxidative stress is also acquired.
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Affiliation(s)
- Hoa Thanh Nguyen
- Laboratory of Environmental Toxicology, Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama, 790-8577, Japan
| | - Maria Claret Lauan Tsuchiya
- Laboratory of Environmental Toxicology, Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama, 790-8577, Japan.,Institute of Biological Sciences, University of the Philippines Los Baños, Laguna, Philippines
| | - Jean Yoo
- Laboratory of Environmental Toxicology, Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama, 790-8577, Japan
| | - Midori Iida
- Graduate School of Computer Science and System Engineering, Kyushu Institute of Technology, Iizuka, 820-0067, Japan
| | - Tetsuro Agusa
- Laboratory of Environmental Toxicology, Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama, 790-8577, Japan.,Graduate School of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto, 862-8502, Japan
| | - Masashi Hirano
- Laboratory of Environmental Toxicology, 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, Seoul, 130-701, Korea
| | | | - Masato Nose
- Institute for Promotion of Advanced Science and Technology, Ehime University, Matsuyama, 790-8577, Japan
| | - Hisato Iwata
- Laboratory of Environmental Toxicology, Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama, 790-8577, Japan.
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Bak SM, Iida M, Soshilov AA, Denison MS, Iwata H, Kim EY. Auto-induction mechanism of aryl hydrocarbon receptor 2 (AHR2) gene by TCDD-activated AHR1 and AHR2 in the red seabream (Pagrus major). Arch Toxicol 2016; 91:301-312. [PMID: 27188387 DOI: 10.1007/s00204-016-1732-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 04/27/2016] [Indexed: 11/26/2022]
Abstract
The toxic effects of dioxins and related compounds (DRCs) are mediated by the aryl hydrocarbon receptor (AHR). Our previous study identified AHR1 and AHR2 genes from the red seabream (Pagrus major). Moreover, we found that AHR2 mRNA levels were notably elevated by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure in the early life stage of red seabream embryos, while AHR1 mRNA level was not altered. In this study, to investigate the regulatory mechanism of these AHR transcripts, we cloned and characterized 5'-flanking regions of AHR1 and AHR2 genes. Both of the 5'-flanking regions in these AHR genes contained three potential xenobiotic-responsive elements (XREs). To assess whether the 5'-flanking region is transactivated by rsAHR1 and rsAHR2 proteins, we measured the transactivation potency of the luciferase reporter plasmids containing the 5'-flanking regions by AHR1 and AHR2 proteins that were transiently co-expressed in COS-7. Only reporter plasmid (pGL4-rsAHR2-3XREs) that contained three putative XRE sites in the 5'-flanking region of AHR2 gene showed a clear TCDD dose-dependent transactivation by AHR1 and AHR2 proteins. TCDD-EC50 values for the rsAHR2-derived XRE transactivation were 1.3 and 1.4 nM for AHR1 and AHR2, respectively. These results suggest that the putative XREs of AHR2 gene have a function for AHR1- and AHR2-mediated transactivation, supporting our in ovo observation of an induction of AHR2 mRNA levels by TCDD exposure. Mutations in XREs of AHR2 gene led to a decrease in luciferase induction. Electrophoretic mobility shift assay showed that XRE1, the closest XRE from the start codon in AHR2 gene, is mainly responsible for the binding with TCDD-activated AHR. This suggests that TCDD-activated AHR1 and AHR2 up-regulate the AHR2 mRNA levels and this auto-induced AHR2 may amplify the signal transduction of its downstream targets including CYP1A in the red seabream.
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Affiliation(s)
- Su-Min Bak
- Department of Life and Nanopharmaceutical Science, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 130-701, Korea
- Department of Biology, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 130-701, Korea
| | - Midori Iida
- Laboratory of Environmental Toxicology, Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matsuyama, 790-8577, Japan
| | - Anatoly A Soshilov
- 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
| | - Hisato Iwata
- Laboratory of Environmental Toxicology, Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matsuyama, 790-8577, Japan
| | - Eun-Young Kim
- Department of Life and Nanopharmaceutical Science, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 130-701, Korea.
- Department of Biology, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 130-701, Korea.
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