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Solvay M, Holfelder P, Klaessens S, Pilotte L, Stroobant V, Lamy J, Naulaerts S, Spillier Q, Frédérick R, De Plaen E, Sers C, Opitz CA, Van den Eynde BJ, Zhu J. Tryptophan depletion sensitizes the AHR pathway by increasing AHR expression and GCN2/LAT1-mediated kynurenine uptake, and potentiates induction of regulatory T lymphocytes. J Immunother Cancer 2023; 11:e006728. [PMID: 37344101 DOI: 10.1136/jitc-2023-006728] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/12/2023] [Indexed: 06/23/2023] Open
Abstract
BACKGROUND Indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan-dioxygenase (TDO) are enzymes catabolizing the essential amino acid tryptophan into kynurenine. Expression of these enzymes is frequently observed in advanced-stage cancers and is associated with poor disease prognosis and immune suppression. Mechanistically, the respective roles of tryptophan shortage and kynurenine production in suppressing immunity remain unclear. Kynurenine was proposed as an endogenous ligand for the aryl hydrocarbon receptor (AHR), which can regulate inflammation and immunity. However, controversy remains regarding the role of AHR in IDO1/TDO-mediated immune suppression, as well as the involvement of kynurenine. In this study, we aimed to clarify the link between IDO1/TDO expression, AHR pathway activation and immune suppression. METHODS AHR expression and activation was analyzed by RT-qPCR and western blot analysis in cells engineered to express IDO1/TDO, or cultured in medium mimicking tryptophan catabolism by IDO1/TDO. In vitro differentiation of naïve CD4+ T cells into regulatory T cells (Tregs) was compared in T cells isolated from mice bearing different Ahr alleles or a knockout of Ahr, and cultured in medium with or without tryptophan and kynurenine. RESULTS We confirmed that IDO1/TDO expression activated AHR in HEK-293-E cells, as measured by the induction of AHR target genes. Unexpectedly, AHR was also overexpressed on IDO1/TDO expression. AHR overexpression did not depend on kynurenine but was triggered by tryptophan deprivation. Multiple human tumor cell lines overexpressed AHR on tryptophan deprivation. AHR overexpression was not dependent on general control non-derepressible 2 (GCN2), and strongly sensitized the AHR pathway. As a result, kynurenine and other tryptophan catabolites, which are weak AHR agonists in normal conditions, strongly induced AHR target genes in tryptophan-depleted conditions. Tryptophan depletion also increased kynurenine uptake by increasing SLC7A5 (LAT1) expression in a GCN2-dependent manner. Tryptophan deprivation potentiated Treg differentiation from naïve CD4+ T cells isolated from mice bearing an AHR allele of weak affinity similar to the human AHR. CONCLUSIONS Tryptophan deprivation sensitizes the AHR pathway by inducing AHR overexpression and increasing cellular kynurenine uptake. As a result, tryptophan catabolites such as kynurenine more potently activate AHR, and Treg differentiation is promoted. Our results propose a molecular explanation for the combined roles of tryptophan deprivation and kynurenine production in mediating IDO1/TDO-induced immune suppression.
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Affiliation(s)
- Marie Solvay
- de Duve Institute, UCLouvain, Brussels, Belgium
- Ludwig Institute for Cancer Research, de Duve Institute, Brussels, Belgium
| | - Pauline Holfelder
- Faculty of Bioscience, Heidelberg University, Heidelberg, Germany
- DKTK Division of Metabolic Crosstalk in Cancer, German Cancer Research Center, DKFZ, INF 280, 69120 Heidelberg, Germany
| | - Simon Klaessens
- de Duve Institute, UCLouvain, Brussels, Belgium
- Ludwig Institute for Cancer Research, de Duve Institute, Brussels, Belgium
| | - Luc Pilotte
- de Duve Institute, UCLouvain, Brussels, Belgium
- Ludwig Institute for Cancer Research, de Duve Institute, Brussels, Belgium
| | - Vincent Stroobant
- de Duve Institute, UCLouvain, Brussels, Belgium
- Ludwig Institute for Cancer Research, de Duve Institute, Brussels, Belgium
| | - Juliette Lamy
- de Duve Institute, UCLouvain, Brussels, Belgium
- Ludwig Institute for Cancer Research, de Duve Institute, Brussels, Belgium
| | - Stefan Naulaerts
- de Duve Institute, UCLouvain, Brussels, Belgium
- Ludwig Institute for Cancer Research, de Duve Institute, Brussels, Belgium
| | | | | | - Etienne De Plaen
- de Duve Institute, UCLouvain, Brussels, Belgium
- Ludwig Institute for Cancer Research, de Duve Institute, Brussels, Belgium
| | - Christine Sers
- Partner Site Berlin, German Cancer Consortium, Heidelberg, Germany
- German Cancer Consortium Partner Site Berlin, German Cancer Research Center, Heidelberg, Germany
| | - Christiane A Opitz
- DKTK Division of Metabolic Crosstalk in Cancer, German Cancer Research Center, DKFZ, INF 280, 69120 Heidelberg, Germany
- Neurology Clinic and National Center for Tumor Diseases, Heidelberg, Germany
| | - Benoit J Van den Eynde
- de Duve Institute, UCLouvain, Brussels, Belgium
- Ludwig Institute for Cancer Research, de Duve Institute, Brussels, Belgium
| | - Jingjing Zhu
- de Duve Institute, UCLouvain, Brussels, Belgium
- Ludwig Institute for Cancer Research, de Duve Institute, Brussels, Belgium
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Aryl Hydrocarbon Receptor Activation by Benzo[ a]pyrene Prevents Development of Septic Shock and Fatal Outcome in a Mouse Model of Systemic Salmonella enterica Infection. Cells 2022; 11:cells11040737. [PMID: 35203386 PMCID: PMC8870598 DOI: 10.3390/cells11040737] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 02/11/2022] [Accepted: 02/13/2022] [Indexed: 02/04/2023] Open
Abstract
This study focused on immunomodulatory effects of aryl hydrocarbon receptor (AhR) activation through benzo[a]pyrene (BaP) during systemic bacterial infection. Using a well-established mouse model of systemic Salmonella enterica (S.E.) infection, we studied the influence of BaP on the cellular and humoral immune response and the outcome of disease. BaP exposure significantly reduced mortality, which is mainly caused by septic shock. Surprisingly, the bacterial burden in BaP-exposed surviving mice was significantly higher compared to non-exposed mice. During the early phase of infection (days 1-3 post-infection (p.i.)), the transcription of proinflammatory factors (i.e., IL-12, IFN-γ, TNF-α, IL-1β, IL-6, IL-18) was induced faster under BaP exposure. Moreover, BaP supported the activity of antigen-presenting cells (i.e., CD64 (FcγRI), MHC II, NO radicals, phagocytosis) at the site of infection. However, early in infection, the anti-inflammatory cytokines IL-10 and IL-22 were also locally and systemically upregulated in BaP-exposed S.E.-infected mice. BaP-exposure resulted in long-term persistence of salmonellae up to day 90 p.i., which was accompanied by significantly elevated S.E.-specific antibody responses (i.e., IgG1, IgG2c). In summary, these data suggest that BaP-induced AhR activation is capable of preventing a fatal outcome of systemic S.E. infection, but may result in long-term bacterial persistence, which, in turn, may support the development of chronic inflammation.
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The Aryl Hydrocarbon Receptor (AHR): A Novel Therapeutic Target for Pulmonary Diseases? Int J Mol Sci 2022; 23:ijms23031516. [PMID: 35163440 PMCID: PMC8836075 DOI: 10.3390/ijms23031516] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 12/30/2021] [Accepted: 01/13/2022] [Indexed: 01/08/2023] Open
Abstract
The aryl hydrocarbon receptor (AHR) is a cytoplasmic transcription factor that is well-known for regulating xenobiotic metabolism. Studies in knockout and transgenic mice indicate that the AHR plays a vital role in the development of liver and regulation of reproductive, cardiovascular, hematopoietic, and immune homeostasis. In this focused review on lung diseases associated with acute injury and alveolar development, we reviewed and summarized the current literature on the mechanistic role(s) and therapeutic potential of the AHR in acute lung injury, chronic obstructive pulmonary disease, and bronchopulmonary dysplasia (BPD). Pre-clinical studies indicate that endogenous AHR activation is necessary to protect neonatal and adult lungs against hyperoxia- and cigarette smoke-induced injury. Our goal is to provide insight into the high translational potential of the AHR in the meaningful management of infants and adults with these lung disorders that lack curative therapies.
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Barroso A, Mahler JV, Fonseca-Castro PH, Quintana FJ. The aryl hydrocarbon receptor and the gut-brain axis. Cell Mol Immunol 2021; 18:259-268. [PMID: 33408340 PMCID: PMC8027889 DOI: 10.1038/s41423-020-00585-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 10/29/2020] [Indexed: 12/11/2022] Open
Abstract
The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor initially identified as the receptor for dioxin. Almost half a century after its discovery, AHR is now recognized as a receptor for multiple physiological ligands, with important roles in health and disease. In this review, we discuss the role of AHR in the gut-brain axis and its potential value as a therapeutic target for immune-mediated diseases.
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Affiliation(s)
- Andreia Barroso
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - João Vitor Mahler
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
- Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Pedro Henrique Fonseca-Castro
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
- Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Francisco J Quintana
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
- Broad Institute of MIT and Harvard, Cambridge, MA, USA.
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5
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Matvere A, Teino I, Varik I, Kuuse S, Tiido T, Kristjuhan A, Maimets T. FSH/LH-Dependent Upregulation of Ahr in Murine Granulosa Cells Is Controlled by PKA Signaling and Involves Epigenetic Regulation. Int J Mol Sci 2019; 20:ijms20123068. [PMID: 31234584 PMCID: PMC6627912 DOI: 10.3390/ijms20123068] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 06/20/2019] [Accepted: 06/21/2019] [Indexed: 12/12/2022] Open
Abstract
The aryl hydrocarbon receptor (Ahr) is a ligand-activated transcription factor primarily known for its toxicological functions. Recent studies have established its importance in many physiological processes including female reproduction, although there is limited data about the precise mechanisms how Ahr itself is regulated during ovarian follicle maturation. This study describes the expression of Ahr in ovarian granulosa cells (GCs) of immature mice in a gonadotropin-dependent manner. We show that Ahr upregulation in vivo requires both follicle stimulating hormone (FSH) and luteinizing hormone (LH) activities. FSH alone increased Ahr mRNA, but had no effect on Ahr protein level, implicating a possible LH-dependent post-transcriptional regulation. Also, the increase in Ahr protein is specific to large antral follicles in induced follicle maturation. We show that Ahr expression in GCs of mid-phase follicular maturation is downregulated by protein kinase A (PKA) signaling and activation of Ahr promoter is regulated by chromatin remodeling.
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Affiliation(s)
- Antti Matvere
- Department of Cell Biology, Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia.
| | - Indrek Teino
- Department of Cell Biology, Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia.
| | - Inge Varik
- Department of Cell Biology, Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia.
| | - Sulev Kuuse
- Department of Cell Biology, Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia.
| | - Tarmo Tiido
- Clinical Research Centre, National Centre of Translational and Clinical Research, University of Tartu, Ravila 19, 50411 Tartu, Estonia.
| | - Arnold Kristjuhan
- Department of Cell Biology, Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia.
| | - Toivo Maimets
- Department of Cell Biology, Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia.
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Loss of NR2E3 represses AHR by LSD1 reprogramming, is associated with poor prognosis in liver cancer. Sci Rep 2017; 7:10662. [PMID: 28878246 PMCID: PMC5587550 DOI: 10.1038/s41598-017-11106-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 08/18/2017] [Indexed: 11/15/2022] Open
Abstract
The aryl hydrocarbon receptor (AHR) plays crucial roles in inflammation, metabolic disorder, and cancer. However, the molecular mechanisms regulating AHR expression remain unknown. Here, we found that an orphan nuclear NR2E3 maintains AHR expression, and forms an active transcriptional complex with transcription factor Sp1 and coactivator GRIP1 in MCF-7 human breast and HepG2 liver cancer cell lines. NR2E3 loss promotes the recruitment of LSD1, a histone demethylase of histone 3 lysine 4 di-methylation (H3K4me2), to the AHR gene promoter region, resulting in repression of AHR expression. AHR expression and responsiveness along with H3K4me2 were significantly reduced in the livers of Nr2e3rd7 (Rd7) mice that express low NR2E3 relative to the livers of wild-type mice. SP2509, an LSD1 inhibitor, fully restored AHR expression and H3K4me2 levels in Rd7 mice. Lastly, we demonstrated that both AHR and NR2E3 are significantly associated with good clinical outcomes in liver cancer. Together, our results reveal a novel link between NR2E3, AHR, and liver cancer via LSD1-mediated H3K4me2 histone modification in liver cancer development.
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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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8
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Yamashita S, Baba K, Makio A, Kumazoe M, Huang Y, Lin IC, Bae J, Murata M, Yamada S, Tachibana H. γ-Tocotrienol upregulates aryl hydrocarbon receptor expression and enhances the anticancer effect of baicalein. Biochem Biophys Res Commun 2016; 473:801-807. [DOI: 10.1016/j.bbrc.2016.03.111] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 03/23/2016] [Indexed: 01/18/2023]
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9
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Tarnow P, Tralau T, Luch A. G protein-coupled receptor 30 ligand G-1 increases aryl hydrocarbon receptor signalling by inhibition of tubulin assembly and cell cycle arrest in human MCF-7 cells. Arch Toxicol 2015; 90:1939-48. [DOI: 10.1007/s00204-015-1615-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 10/01/2015] [Indexed: 11/30/2022]
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10
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Harkitis P, Daskalopoulos EP, Malliou F, Lang MA, Marselos M, Fotopoulos A, Albucharali G, Konstandi M. Dopamine D2-Receptor Antagonists Down-Regulate CYP1A1/2 and CYP1B1 in the Rat Liver. PLoS One 2015; 10:e0128708. [PMID: 26466350 PMCID: PMC4605514 DOI: 10.1371/journal.pone.0128708] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 04/29/2015] [Indexed: 12/26/2022] Open
Abstract
Dopaminergic systems regulate the release of several hormones including growth hormone (GH), thyroid hormones, insulin, glucocorticoids and prolactin (PRL) that play significant roles in the regulation of various Cytochrome P450 (CYP) enzymes. The present study investigated the role of dopamine D2-receptor-linked pathways in the regulation of CYP1A1, CYP1A2 and CYP1B1 that belong to a battery of genes controlled by the Aryl Hydrocarbon Receptor (AhR) and play a crucial role in the metabolism and toxicity of numerous environmental toxicants. Inhibition of dopamine D2-receptors with sulpiride (SULP) significantly repressed the constitutive and benzo[a]pyrene (B[a]P)-induced CYP1A1, CYP1A2 and CYP1B expression in the rat liver. The expression of AhR, heat shock protein 90 (HSP90) and AhR nuclear translocator (ARNT) was suppressed by SULP in B[a]P-treated livers, whereas the AhRR expression was increased by the drug suggesting that the SULP-mediated repression of the CYP1 inducibility is due to inactivation of the AhR regulatory system. At signal transduction level, the D2-mediated down-regulation of constitutive CYP1A1/2 and CYP1B1 expression appears to be mediated by activation of the insulin/PI3K/AKT pathway. PRL-linked pathways exerting a negative control on various CYPs, and inactivation of the glucocorticoid-linked pathways that positively control the AhR-regulated CYP1 genes, may also participate in the SULP-mediated repression of both, the constitutive and induced CYP1 expression. The present findings indicate that drugs acting as D2-dopamine receptor antagonists can modify several hormone systems that regulate the expression of CYP1A1, CYP1A2 and CYP1B1, and may affect the toxicity and carcinogenicity outcome of numerous toxicants and pre-carcinogenic substances. Therefore, these drugs could be considered as a part of the strategy to reduce the risk of exposure to environmental pollutants and pre-carcinogens.
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Affiliation(s)
- P. Harkitis
- Department of Pharmacology, Faculty of Medicine, University of Ioannina, Ioannina GR-451 10, Greece
| | - E. P. Daskalopoulos
- Department of Pharmacology, Faculty of Medicine, University of Ioannina, Ioannina GR-451 10, Greece
| | - F. Malliou
- Department of Pharmacology, Faculty of Medicine, University of Ioannina, Ioannina GR-451 10, Greece
| | - M. A. Lang
- University of Queensland, National Research Centre for Environmental Toxicology (Entox), 39 Kessels Road, Coopers Plains, QLD 4108, Australia
| | - M. Marselos
- Department of Pharmacology, Faculty of Medicine, University of Ioannina, Ioannina GR-451 10, Greece
| | - A. Fotopoulos
- Department of Nuclear Medicine, Faculty of Medicine, University of Ioannina, Ioannina GR-451 10, Greece
| | - G. Albucharali
- Department of Nuclear Medicine, Faculty of Medicine, University of Ioannina, Ioannina GR-451 10, Greece
| | - M. Konstandi
- Department of Pharmacology, Faculty of Medicine, University of Ioannina, Ioannina GR-451 10, Greece
- * E-mail:
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11
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Vogel CFA, Khan EM, Leung PSC, Gershwin ME, Chang WLW, Wu D, Haarmann-Stemmann T, Hoffmann A, Denison MS. Cross-talk between aryl hydrocarbon receptor and the inflammatory response: a role for nuclear factor-κB. J Biol Chem 2014; 289:1866-75. [PMID: 24302727 PMCID: PMC3894361 DOI: 10.1074/jbc.m113.505578] [Citation(s) in RCA: 196] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 11/26/2013] [Indexed: 01/13/2023] Open
Abstract
The aryl hydrocarbon receptor (AhR) is involved in the regulation of immune responses, T-cell differentiation, and immunity. Here, we show that inflammatory stimuli such as LPS induce the expression of AhR in human dendritic cells (DC) associated with an AhR-dependent increase of CYP1A1 (cytochrome P4501A1). In vivo data confirmed the elevated expression of AhR by LPS and the LPS-enhanced 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-mediated induction of CYP1A1 in thymus of B6 mice. Inhibition of nuclear factor-κB (NF-κB) repressed both normal and LPS-enhanced, TCDD-inducible, AhR-dependent gene expression and canonical pathway control of RelA-regulated AhR-responsive gene expression. LPS-mediated induction of AhR was NF-κB-dependent, as shown in mouse embryonic fibroblasts (MEFs) derived from Rel null mice. AhR expression and TCDD-mediated induction of CYP1A1 was significantly reduced in RelA-deficient MEF compared with wild type MEF cells and ectopic expression of RelA restored the expression of AhR and induction of CYP1A1 in MEF RelA null cells. Promoter analysis of the human AhR gene identified three putative NF-κB-binding elements upstream of the transcription start site. Mutation analysis of the AhR promoter identified one NF-κB site as responsible for mediating the induction of AhR expression by LPS and electrophoretic shift assays demonstrated that this NF-κB motif is recognized by the RelA/p50 heterodimer. Our results show for the first time that NF-κB RelA is a critical component regulating the expression of AhR and the induction of AhR-dependent gene expression in immune cells illustrating the interaction of AhR and NF-κB signaling.
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Affiliation(s)
- Christoph F. A. Vogel
- From the Department of Environmental Toxicology
- Center for Health and the Environment
| | | | | | | | - W. L. William Chang
- Center for Comparative Medicine, University of California, Davis, California 95616
| | - Dalei Wu
- the Sanford-Burnham Medical Research Institute, Orlando, Florida 32827
| | | | - Alexander Hoffmann
- the Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, California 90025
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Ko CI, Wang Q, Fan Y, Xia Y, Puga A. Pluripotency factors and Polycomb Group proteins repress aryl hydrocarbon receptor expression in murine embryonic stem cells. Stem Cell Res 2013; 12:296-308. [PMID: 24316986 DOI: 10.1016/j.scr.2013.11.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 11/07/2013] [Accepted: 11/08/2013] [Indexed: 11/18/2022] Open
Abstract
The aryl hydrocarbon receptor (AHR) is a transcription factor and environmental sensor that regulates expression of genes involved in drug-metabolism and cell cycle regulation. Chromatin immunoprecipitation analyses, Ahr ablation in mice and studies with orthologous genes in invertebrates suggest that AHR may also play a significant role in embryonic development. To address this hypothesis, we studied the regulation of Ahr expression in mouse embryonic stem cells and their differentiated progeny. In ES cells, interactions between OCT3/4, NANOG, SOX2 and Polycomb Group proteins at the Ahr promoter repress AHR expression, which can also be repressed by ectopic expression of reprogramming factors in hepatoma cells. In ES cells, unproductive RNA polymerase II binds at the Ahr transcription start site and drives the synthesis of short abortive transcripts. Activation of Ahr expression during differentiation follows from reversal of repressive marks in Ahr promoter chromatin, release of pluripotency factors and PcG proteins, binding of Sp factors, establishment of histone marks of open chromatin, and engagement of active RNAPII to drive full-length RNA transcript elongation. Our results suggest that reversible Ahr repression in ES cells holds the gene poised for expression and allows for a quick switch to activation during embryonic development.
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Affiliation(s)
- Chia-I Ko
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, 3223 Eden Avenue, Cincinnati, OH 45267, USA
| | - Qin Wang
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, 3223 Eden Avenue, Cincinnati, OH 45267, USA
| | - Yunxia Fan
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, 3223 Eden Avenue, Cincinnati, OH 45267, USA
| | - Ying Xia
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, 3223 Eden Avenue, Cincinnati, OH 45267, USA
| | - Alvaro Puga
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, 3223 Eden Avenue, Cincinnati, OH 45267, USA.
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Stobbe-Maicherski N, Wolff S, Wolff C, Abel J, Sydlik U, Frauenstein K, Haarmann-Stemmann T. The interleukin-6-type cytokine oncostatin M induces aryl hydrocarbon receptor expression in a STAT3-dependent manner in human HepG2 hepatoma cells. FEBS J 2013; 280:6681-90. [DOI: 10.1111/febs.12571] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 09/19/2013] [Accepted: 10/10/2013] [Indexed: 12/28/2022]
Affiliation(s)
| | - Sandra Wolff
- IUF - Leibniz Research Institute for Environmental Medicine; Duesseldorf Germany
| | - Christian Wolff
- IUF - Leibniz Research Institute for Environmental Medicine; Duesseldorf Germany
| | - Josef Abel
- IUF - Leibniz Research Institute for Environmental Medicine; Duesseldorf Germany
| | - Ulrich Sydlik
- IUF - Leibniz Research Institute for Environmental Medicine; Duesseldorf Germany
| | - Katrin Frauenstein
- IUF - Leibniz Research Institute for Environmental Medicine; Duesseldorf Germany
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14
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Chan JKW, Vogel CF, Baek J, Kodani SD, Uppal RS, Bein KJ, Anderson DS, Van Winkle LS. Combustion derived ultrafine particles induce cytochrome P-450 expression in specific lung compartments in the developing neonatal and adult rat. Am J Physiol Lung Cell Mol Physiol 2013; 304:L665-77. [PMID: 23502512 DOI: 10.1152/ajplung.00370.2012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Vehicle exhaust is rich in polycyclic aromatic hydrocarbons (PAH) and can be a dominant contributor to ultrafine urban particulate matter (PM). Exposure to ultrafine PM is correlated with respiratory infections and asthmatic symptoms in young children. The lung undergoes substantial growth, alveolarization, and cellular maturation within the first years of life, which may be impacted by environmental pollutants such as PM. PAHs in PM can serve as ligands for the aryl hydrocarbon receptor (AhR) that induces expression of certain isozymes in the cytochrome P-450 superfamily, such as CYP1A1 and CYP1B1, localized in specific lung cell types. Although AhR activation and induction has been widely studied, its context within PM exposure and impact on the developing lung is poorly understood. In response, we have developed a replicable ultrafine premixed flame particle (PFP) generating system and used in vitro and in vivo models to define PM effects on AhR activation in the developing lung. We exposed 7-day neonatal and adult rats to a single 6-h PFP exposure and determined that PFPs cause significant parenchymal toxicity in neonates. PFPs contain weak AhR agonists that upregulate AhR-xenobiotic response element activity and expression and are capable inducers of CYP1A1 and CYP1B1 expression in both ages with different spatial and temporal patterns. Neonatal CYP1A1 expression was muted and delayed compared with adults, possibly because of differences in the enzyme maturation. We conclude that the inability of neonates to sufficiently adapt in response to PFP exposure may, in part, explain their susceptibility to PFP and urban ultrafine PM.
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Affiliation(s)
- Jackie K W Chan
- Center for Health and the Environment, University of California, Davis, Davis, CA 95616, USA
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15
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Englert NA, Turesky RJ, Han W, Bessette EE, Spivack SD, Caggana M, Spink DC, Spink BC. Genetic and epigenetic regulation of AHR gene expression in MCF-7 breast cancer cells: role of the proximal promoter GC-rich region. Biochem Pharmacol 2012; 84:722-35. [PMID: 22728919 DOI: 10.1016/j.bcp.2012.06.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 06/14/2012] [Accepted: 06/14/2012] [Indexed: 10/28/2022]
Abstract
The aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor, contributes to carcinogenesis through its role in the regulation of cytochrome P450 1 (CYP1)-catalyzed metabolism of carcinogens. Here, we investigated genetic and epigenetic mechanisms that affect AhR expression. Analyses of the human AHR proximal promoter in MCF-7 human breast cancer cells using luciferase assays and electrophoretic mobility shift assays revealed multiple specificity protein (Sp) 1 binding sequences that are transcriptional activators in vitro. The regulation of AhR expression was evaluated in long-term estrogen exposed (LTEE) MCF-7 cells, which showed increased AhR expression, enhanced CYP1 inducibility, and increased capacity to form DNA adducts when exposed to the dietary carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine. The increased AhR expression in LTEE cells was found not to result from increased mRNA stability, differential RNA processing, or decreased DNA methylation. Analysis of the AHR proximal promoter region using chromatin immunoprecipitation confirmed that enhanced expression of AhR in LTEE cells involves changes in histone modifications, notably decreased trimethylation of histone 3, lysine 27. Upon further examination of the GC-rich Sp1-binding region, we confirmed that it contains a polymorphic (GGGGC)(n) repeat. In a population of newborns from New York State, the allele frequency of (GGGGC)(n) was n = 4 > 5 ≫ 6, 2. Circular dichroism spectroscopy revealed the ability of sequences of this GC-rich region to form guanine-quadruplex structures in vitro. These studies revealed multiple levels at which AhR expression may be controlled, and offer additional insights into mechanisms regulating AhR expression that can ultimately impact carcinogenesis.
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Affiliation(s)
- Neal A Englert
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
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16
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Lin X, Yang H, Zhou L, Guo Z. Nrf2-dependent induction of NQO1 in mouse aortic endothelial cells overexpressing catalase. Free Radic Biol Med 2011; 51:97-106. [PMID: 21569840 PMCID: PMC3109219 DOI: 10.1016/j.freeradbiomed.2011.04.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 03/28/2011] [Accepted: 04/11/2011] [Indexed: 11/17/2022]
Abstract
Overexpression of catalase has been shown to accelerate benzo(a)pyrene (BaP) detoxification in mouse aortic endothelial cells (MAECs). NAD(P)H:quinone oxidoreductase-1 (NQO1) is an enzyme that catalyzes BaP-quinone detoxification. Aryl hydrocarbon receptor (AhR) and nuclear factor erythroid 2-related factor-2 (Nrf2) are transcription factors that control NQO1 expression. Here, we investigated the effects of catalase overexpression on NQO1, Nrf2, and AhR expression. The levels of NQO1 mRNA and protein were comparable in MAECs isolated from wild-type and transgenic mice that overexpress human catalase (hCatTg). BaP treatment increased NQO1 mRNA and protein levels in both groups, with a significantly greater induction in hCatTg MAECs than in wild-type cells. BaP-induced NQO1 promoter activity was dramatically higher in hCatTg MAECs than in wild-type cells. Our data also showed that the basal level of AhR and the BaP-induced level of Nrf2 were significantly higher in hCatTg MAECs than in wild-type cells. Inhibition of specificity protein-1 (Sp1) binding to the AhR promoter region by mithramycin A reversed the enhancing effect of catalase overexpression on AhR expression. Knockdown of AhR by RNA interference diminished BaP-induced expression of Nrf2 and NQO1. Knockdown of Nrf2 significantly decreased NQO1 mRNA and protein levels in cells with or without BaP treatment. NQO1 promoter activity was abrogated by mutation of the Nrf2-binding site in this promoter. In contrast, mutation of the AhR-binding site in the NQO1 promoter did not affect the promoter activity. These results suggest that catalase overexpression upregulates BaP-induced NQO1 expression by enhancing the Sp1-AhR-Nrf2 signaling cascade.
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Affiliation(s)
| | | | | | - ZhongMao Guo
- Correspondence author: Department of Physiology Meharry Medical College Nashville, TN 37208 Phone: (615) 327-6804 Fax: (615) 321-2949
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17
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Abel J, Haarmann-Stemmann T. An introduction to the molecular basics of aryl hydrocarbon receptor biology. Biol Chem 2011; 391:1235-48. [PMID: 20868221 DOI: 10.1515/bc.2010.128] [Citation(s) in RCA: 208] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Depending on their chemical structure and properties, environmental chemicals and other xenobiotics that enter the cell can affect cellular function by either nonselective binding to cellular macromolecules or by interference with cellular receptors, which would initiate a more defined cell biological response. One of these intracellular chemosensor molecules is the aryl hydrocarbon receptor (AhR), a transcription factor of the bHLH/PAS family that is known to mediate the biochemical and toxic effects of dioxins, polyaromatic hydrocarbons and related compounds. Numerous investigations have revealed that the AhR is not only a master regulator of drug metabolism activated by anthropogenic chemicals, but is also triggered by natural and endogenous ligands and can influence cell biological endpoints such as growth and differentiation. Cutting-edge research has identified new intriguing functions of the AhR, such as during proteasomal degradation of steroid hormone receptors, the cellular UVB stress response and the differentiation of certain T-cell subsets. In this review we provide both a survey of the fundamental basics of AhR biology and an insight into new functional aspects of AhR signaling to further stimulate research on this intriguing transcription factor at the interface between toxicology, cell biology and immunology.
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Affiliation(s)
- Josef Abel
- Institut für Umweltmedizinische Forschung (IUF) an der Heinrich-Heine-Universität Düsseldorf gGmbH, Auf'm Hennekamp 50, Düsseldorf, Germany
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18
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Tang T, Lin X, Yang H, Zhou L, Wang Z, Shan G, Guo Z. Overexpression of antioxidant enzymes upregulates aryl hydrocarbon receptor expression via increased Sp1 DNA-binding activity. Free Radic Biol Med 2010; 49:487-92. [PMID: 20478378 PMCID: PMC2913407 DOI: 10.1016/j.freeradbiomed.2010.05.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 03/25/2010] [Accepted: 05/08/2010] [Indexed: 11/30/2022]
Abstract
We previously reported upregulation of aryl hydrocarbon receptor (AhR) expression as a mechanism by which overexpression of Cu/Zn-superoxide dismutase (SOD) and/or catalase accelerates benzo(a)pyrene (BaP) detoxification in mouse aorta endothelial cells (MAECs). The objective of this study was to investigate the regulatory role of specificity protein-1 (Sp1) in AhR expression in MAECs that overexpress Cu/Zn-SOD and/or catalase. Our data demonstrated comparable levels of nuclear Sp1 protein in the transgenic and wild-type MAECs; however, binding of Sp1 protein to the AhR promoter region was more than 2-fold higher in MAECs overexpressing Cu/Zn-SOD and/or catalase than in wild-type cells. Inhibition of Sp1 binding to the AhR promoter by mithramycin A reduced AhR expression and eliminated the differences between wild-type MAECs and three lines of transgenic cells. Functional promoter analysis indicated that AhR promoter activity was significantly higher in MAECs overexpressing catalase than in wild-type cells. Mutation of an AhR promoter Sp1-binding site or addition of hydrogen peroxide to the culture medium reduced AhR promoter activity, and decreased the differences between wild-type MAECs and transgenic cells overexpressing catalase. These results suggest that increased Sp1 binding to the AhR promoter region is an underlying mechanism for upregulation of AhR expression in MAECs that overexpress Cu/Zn-SOD and/or catalase.
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Affiliation(s)
- Tian Tang
- Department of Physiology, Meharry Medical College, Nashville, TN 37208
- Remin Hospital of Wuhan University, Wuhan 430060, PR China
| | - Xinghua Lin
- Department of Physiology, Meharry Medical College, Nashville, TN 37208
| | - Hong Yang
- Department of Physiology, Meharry Medical College, Nashville, TN 37208
| | - LiChun Zhou
- Department of Physiology, Meharry Medical College, Nashville, TN 37208
| | - Zefen Wang
- Department of Physiology, Meharry Medical College, Nashville, TN 37208
| | - Guang Shan
- Department of Physiology, Meharry Medical College, Nashville, TN 37208
- Remin Hospital of Wuhan University, Wuhan 430060, PR China
| | - ZhongMao Guo
- Department of Physiology, Meharry Medical College, Nashville, TN 37208
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19
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Wang Z, Yang H, Ramesh A, Roberts LJ, Zhou L, Lin X, Zhao Y, Guo Z. Overexpression of Cu/Zn-superoxide dismutase and/or catalase accelerates benzo(a)pyrene detoxification by upregulation of the aryl hydrocarbon receptor in mouse endothelial cells. Free Radic Biol Med 2009; 47:1221-9. [PMID: 19666105 PMCID: PMC2846758 DOI: 10.1016/j.freeradbiomed.2009.08.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2009] [Accepted: 08/01/2009] [Indexed: 01/27/2023]
Abstract
A reduction in endogenously generated reactive oxygen species in vivo delays benzo(a)pyrene (BaP)-accelerated atherosclerosis, as revealed in hypercholesterolemic mice overexpressing Cu/Zn-superoxide dismutase (SOD) and/or catalase. To understand the molecular events involved in this protective action, we studied the effects of Cu/Zn-SOD and/or catalase overexpression on BaP detoxification and on aryl hydrocarbon receptor (AhR) expression and its target gene expression in mouse aortic endothelial cells (MAECs). Our data demonstrate that overexpression of Cu/Zn-SOD and/or catalase leads to an 18- to 20-fold increase in the expression of AhR protein in MAECs. After BaP exposure, the amount of AhR binding to the cytochrome P450 (CYP) 1A1 promoter was significantly greater, and the concentrations of BaP reactive intermediates were significantly less in MAECs overexpressing Cu/Zn-SOD and/or catalase than in wild-type cells. In addition, the BaP-induced CYP1A1 and 1B1 protein levels and BaP-elevated glutathione S-transferase (GST) activity were significantly higher in these transgenic cells, in parallel with elevated GSTp1, CYP1A1, and CYP1B1 mRNA levels, compared to wild-type MAECs. Moreover, knockdown of AhR with RNA interference diminished the Cu/Zn-SOD and catalase enhancement of CYP1A1 expression, GST activity, and BaP detoxification. These data demonstrate that overexpression of Cu/Zn-SOD and/or catalase is associated with upregulation of AhR and its target genes, such as xenobiotic-metabolizing enzymes.
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MESH Headings
- Animals
- Aorta/cytology
- Aorta/metabolism
- Aryl Hydrocarbon Hydroxylases/genetics
- Aryl Hydrocarbon Hydroxylases/metabolism
- Benzo(a)pyrene/pharmacokinetics
- Blotting, Western
- Catalase/metabolism
- Cells, Cultured
- Cytochrome P-450 CYP1A1/genetics
- Cytochrome P-450 CYP1A1/metabolism
- Cytochrome P-450 CYP1B1
- Endothelium, Vascular/cytology
- Endothelium, Vascular/metabolism
- F2-Isoprostanes/metabolism
- Furans/metabolism
- Glutathione Transferase/genetics
- Glutathione Transferase/metabolism
- Inactivation, Metabolic
- Mice
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Small Interfering/pharmacology
- Receptors, Aryl Hydrocarbon/antagonists & inhibitors
- Receptors, Aryl Hydrocarbon/genetics
- Receptors, Aryl Hydrocarbon/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Superoxide Dismutase/metabolism
- Up-Regulation
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Affiliation(s)
- Zefen Wang
- Department of Cardiovascular Biology, Meharry Medical College, Nashville, TN 37208, USA
| | - Hong Yang
- Department of Cardiovascular Biology, Meharry Medical College, Nashville, TN 37208, USA
- Corresponding author. Fax: +1 615 321 2949. (H. Yang), (Z. Guo)
| | - Aramandla Ramesh
- Department of Cancer Biology, Meharry Medical College, Nashville, TN 37208, USA
| | - L. Jackson Roberts
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - LiChun Zhou
- Department of Cardiovascular Biology, Meharry Medical College, Nashville, TN 37208, USA
| | - Xinhua Lin
- Department of Cardiovascular Biology, Meharry Medical College, Nashville, TN 37208, USA
| | - Yanfeng Zhao
- Department of Cardiovascular Biology, Meharry Medical College, Nashville, TN 37208, USA
| | - ZhongMao Guo
- Department of Cardiovascular Biology, Meharry Medical College, Nashville, TN 37208, USA
- Corresponding author. Fax: +1 615 321 2949. (H. Yang), (Z. Guo)
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20
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Frericks M, Meissner M, Esser C. Microarray analysis of the AHR system: Tissue-specific flexibility in signal and target genes. Toxicol Appl Pharmacol 2007; 220:320-32. [PMID: 17350064 DOI: 10.1016/j.taap.2007.01.014] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2006] [Revised: 01/19/2007] [Accepted: 01/19/2007] [Indexed: 01/31/2023]
Abstract
Data mining published microarray experiments require that expression profiles are directly comparable. We performed linear global normalization on the data of 1967 Affymetrix U74av2 microarrays, i.e. the transcriptomes of >100 murine tissues or cell types. The mathematical transformation effectively nullifies inter-experimental or inter-laboratory differences between microarrays. The correctness of expression values was validated by quantitative RT-PCR. Using the database we analyze components of the aryl hydrocarbon receptor (AHR) signaling pathway in various tissues. We identified lineage and differentiation specific variant expression of AHR, ARNT, and HIF1alpha in the T-cell lineage and high expression of CYP1A1 in immature B cells and dendritic cells. Performing co-expression analysis we found unorthodox expression of the AHR in the absence of ARNT, particularly in stem cell populations, and can reject the hypothesis that ARNT2 takes over and is highly expressed when ARNT expression is low or absent. Furthermore the AHR shows no co-expression with any other transcript present on the chip. Analysis of differential gene expression under 308 conditions revealed 53 conditions under which the AHR is regulated, numerous conditions under which an intrinsic AHR action is modified as well as conditions activating the AHR even in the absence of known AHR ligands. Thus meta-analysis of published expression profiles is a powerful tool to gain novel insights into known and unknown systems.
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Affiliation(s)
- Markus Frericks
- Institut für Umweltmedizinische Forschung (IUF) at the Heinrich Heine-University of Düsseldorf, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
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21
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Wang W, Jaiswal AK. Sp3 repression of polymorphic human NRH:quinone oxidoreductase 2 gene promoter. Free Radic Biol Med 2004; 37:1231-43. [PMID: 15451063 DOI: 10.1016/j.freeradbiomed.2004.06.042] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2003] [Revised: 04/20/2004] [Accepted: 06/24/2004] [Indexed: 11/21/2022]
Abstract
Human NRH:quinone oxidoreductase 2 (NQO2) gene-containing 29-bp deletion/insertion polymorphic promoters were found to be associated with susceptibility to Parkinson's disease. Here, we demonstrate that the NQO2 gene is differentially expressed by the polymorphic promoters in human fibroblasts and Hep-G2 cells transfected with NQO2 gene reporter constructs. Promoter containing the 29-bp insertion polymorphism demonstrated significantly lower NQO2 gene expression. Deletion mutagenesis and DNase I footprinting analysis of the promoter without the 29-bp insertion identified three protected regions (region A, B, and C). Band- and supershift and transfection assays showed binding of transcription factor Sp1 to regions A and B, which regulated expression of the NQO2 gene. Similar studies of the NQO2 gene promoter with the 29-bp insertion polymorphism showed that regions A and C were identical and contributed similarly as in the promoter without the 29-bp insertion to NQO2 gene expression. However, region B was found to be inserted with 29-bp DNA element and bound to both Sp1 and Sp3. Binding of Sp3 led to repression of NQO2 gene transcription by the promoter containing the 29-bp insertion polymorphism. These studies also suggest that alterations in NQO2 activity might be an important factor in susceptibility to Parkinson's disease.
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Affiliation(s)
- Wei Wang
- Department of Pharmacology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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22
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Racky J, Schmitz HJ, Kauffmann HM, Schrenk D. Single nucleotide polymorphism analysis and functional characterization of the human Ah receptor (AhR) gene promoter. Arch Biochem Biophys 2004; 421:91-8. [PMID: 14678789 DOI: 10.1016/j.abb.2003.10.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The aryl hydrocarbon receptor (AhR) mediates biological and toxicological actions of e.g., halogenated aromatic hydrocarbons such as 2,3,7,8-tetrachlorodibenzo-p-dioxin. Although much is known about the biochemical and molecular mechanisms of AhR action, little is known about the control of the expression of the AhR gene itself. Therefore, we aimed at the identification and characterization of regions important for constitutive AhR gene expression. First, we screened 2.6 kb of the 5(')-flanking region of the AhR gene in 91 healthy Caucasian volunteers for naturally occurring genetic variants. Seven variants were detected. However, they do not seem to influence AhR gene expression in lymphocytes. Using a 2.7 kb AhR promoter luciferase reporter gene construct and various deletion constructs, a putative regulatory region was identified and characterized further by electrophoretic mobility shift assays and site-directed mutagenesis. These investigations were confirmed by cotransfection experiments in Drosophila SL2 cells. The obtained results prove an involvement of Sp1 in AhR gene regulation.
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MESH Headings
- 5' Flanking Region/genetics
- Animals
- Cell Line
- Cell Line, Tumor
- Cohort Studies
- Cyclic AMP Response Element-Binding Protein/genetics
- Cyclic AMP Response Element-Binding Protein/metabolism
- Drosophila melanogaster
- Female
- Gene Deletion
- Gene Expression
- Genes, Reporter/genetics
- Genotype
- Humans
- Luciferases/metabolism
- Male
- Mutagenesis, Site-Directed
- Polymorphism, Single Nucleotide
- Promoter Regions, Genetic/genetics
- Promoter Regions, Genetic/physiology
- RNA, Messenger/biosynthesis
- Receptors, Aryl Hydrocarbon/genetics
- Receptors, Aryl Hydrocarbon/metabolism
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Transcription, Genetic/genetics
- Transfection
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Affiliation(s)
- Judith Racky
- Food Chemistry and Environmental Toxicology, Technical University of Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern, Germany
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23
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Baba T, Mimura J, Gradin K, Kuroiwa A, Watanabe T, Matsuda Y, Inazawa J, Sogawa K, Fujii-Kuriyama Y. Structure and expression of the Ah receptor repressor gene. J Biol Chem 2001; 276:33101-10. [PMID: 11423533 DOI: 10.1074/jbc.m011497200] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The aryl hydrocarbon receptor (AhR) repressor (AhRR) gene has been isolated and characterized from a mouse genomic library. The gene is distributed as 11 exons in a total length of about 60 kilobase pairs. Fluorescence in situ hybridization analysis has shown that the AhRR gene is located at mouse chromosome 13C2, at rat chromosome 1p11.2, and at human chromosome 5p15.3. The AhRR gene has a TATA-less promoter and several transcription start sites. In addition, putative regulatory DNA sequences such as xenobiotic responsive element (XRE), GC box, and NF-kappaB-binding sites have been identified in the 5'-upstream region of the AhRR gene. Transient transfection analyses of HeLa cells with reporter genes that contain deletions and point mutations in the AhRR promoter revealed that all three XREs mediated the inducible expression of the AhRR gene by 3-methylcholanthrene treatment, and furthermore, GC box sequences were indispensable for a high level of inducible expression and for constitutive expression. Moreover, by using gel mobility shift assays we were able to show that the AhR/Arnt heterodimer binds to the XREs with very low affinity, which is due to three varied nucleotides outside the XRE core sequence. We have also shown that Sp1 and Sp3 can bind to the GC boxes. Finally, both transient transfection analysis and gel mobility shift assay revealed that the AhRR gene is up-regulated by a p65/p50 heterodimer that binds to the NF-kappaB site when the cells has been exposed to 12-O-tetradecanoylphorbol-13-acetate, and this inducible expression was further enhanced by cotreatment of 12-O-tetradecanoylphorbol-13-acetate and 3-methylcholanthrene.
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Affiliation(s)
- T Baba
- Department of Biomolecular Science, Graduate School of Life Science, Tohoku University, Sendai 980-8578, Japan
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24
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Wolff S, Harper PA, Wong JM, Mostert V, Wang Y, Abel J. Cell-specific regulation of human aryl hydrocarbon receptor expression by transforming growth factor-beta(1). Mol Pharmacol 2001; 59:716-24. [PMID: 11259615 DOI: 10.1124/mol.59.4.716] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Previous studies showed that TGF-beta down-regulates aryl hydrocarbon (AhR) expression in human lung carcinoma cells A549. Here we analyzed the molecular mechanisms by which TGF-beta modulates AhR expression. A 5799-nucleotide 5'-flanking region of human AhR gene was isolated. Transient transfection studies of full-length (hAhRP) and deletion promoter constructs indicate the requirement of a cis-regulatory element encompassing -1980 to -1892 for full constitutive activity. Basal hAhRP activity occurs in a cell-specific manner; human hepatoma HepG2 cells possess a 10-fold higher activity compared with A549 cells. TGF-beta exerts cell-specific effects on hAhRP activity. Treatment of cells with 100 pM TGF-beta leads to a 50% inhibition in A549 and a 3-fold induction in HepG2 cells. Deletion mutagenesis identified a TGF-beta-responsive sequence containing a functional conserved Smad-binding element. Transient overexpression of Smad 2, 3, and 4 indicates that these signal transducers modulate hAhRP activity. The down-regulation of AhR by TGF-beta is modulated by 5'-TG-3'-interacting factor (TGIF). Transient overexpression of TGIF in MDA-MB231 and HepG2 cells led to inhibition of hAhRP activity and a similar decrease of AhR mRNA expression. Our findings indicate that Smad proteins are involved in the cell-specific regulation of AhR expression by TGF-beta.
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MESH Headings
- 5' Untranslated Regions/genetics
- Activin Receptors, Type I
- Binding Sites/genetics
- Carcinoma/genetics
- Carcinoma/metabolism
- DNA-Binding Proteins/metabolism
- Dose-Response Relationship, Drug
- Down-Regulation/drug effects
- Homeodomain Proteins/metabolism
- Humans
- Liver Neoplasms/genetics
- Liver Neoplasms/metabolism
- Lung Neoplasms/genetics
- Lung Neoplasms/metabolism
- Mutagenesis, Site-Directed
- Protein Serine-Threonine Kinases/metabolism
- RNA, Messenger/metabolism
- Receptor, Transforming Growth Factor-beta Type I
- Receptors, Aryl Hydrocarbon/genetics
- Receptors, Aryl Hydrocarbon/metabolism
- Receptors, Transforming Growth Factor beta/metabolism
- Regulatory Sequences, Nucleic Acid/genetics
- Repressor Proteins
- Smad2 Protein
- Smad3 Protein
- Smad4 Protein
- Trans-Activators/metabolism
- Transfection
- Transforming Growth Factor beta/pharmacology
- Tumor Cells, Cultured
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Affiliation(s)
- S Wolff
- Department of Experimental Toxicology, Medical Institute of Environmental Hygiene at the Heinrich-Heine-University, Düsseldorf, Germany
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25
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Abstract
The Ah receptor (AhR) is a ligand-dependent transcription factor that mediates biological and toxicological actions of halogenated aromatic hydrocarbons such as 2,3,7,8-tetrachlorodibenzo-p-dioxin. Although much is known about the biochemical and molecular mechanisms of AhR action, little is known about the factors and events that control expression of the AhR gene itself. The 5'-flanking region of the murine AhR gene was characterized and deletion analysis demonstrated that regulatory elements necessary for full constitutive promoter activity are contained within a fragment encompassing -184 to +380 of the AhR gene. The murine AhR gene promoter is a GC-rich, TATA-less promoter that which contains at least five putative Spl-like binding sites. Transient transfection experiments not only identified a region between -1431 and -721 that represses constitutive promoter activity by 2- to 3-fold, but also demonstrate that basal AhR promoter activity occurs in a cell- and species-specific manner. n-Butyrate, a nonspecific histone deacetylase inhibitor, increased AhR promoter activity 8-fold, suggesting a role for histone acetylation in AhR gene promoter activity. Overall, this study defines upstream regulatory regions important for constitutive AhR gene expression and identifies a novel activator of AhR gene expression.
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Affiliation(s)
- P M Garrison
- Department of Environmental Toxicology, University of California, Davis 95616, USA
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Garrison PM, Rogers JM, Brackney WR, Denison MS. Effects of histone deacetylase inhibitors on the Ah receptor gene promoter. Arch Biochem Biophys 2000; 374:161-71. [PMID: 10666294 DOI: 10.1006/abbi.1999.1620] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aromatic hydrocarbon receptor (AhR) is a ligand-dependent basic helix-loop-helix-PAS-containing transcription factor which is activated by chemicals such as 2,3,7,8-tetrachlorodibenzo-p-dioxin. Constitutive expression of the AhR gene occurs in a tissue- and developmentally specific manner and appears to be altered by chemicals which affect histone deacetylase (HDAC) activity in cells in culture. Here we have directly characterized the effects of two HDAC inhibitors, n-butyrate and trichostatin A, on the promoter activity of the murine AhR gene. HDAC inhibitors increased the constitutive activity of the AhR gene promoter in a luciferase reporter construct by five- to sevenfold in a dose- and time-dependent manner in several cell lines and was correlated with an increase in endogenous AhR activity in an AhR-deficient cell line. Deletion analysis of the upstream region of the AhR gene localized the HDAC inhibitor effect to a 167-bp region encompassing -77 to +90 of the AhR gene promoter. Cotransfection of an AhR promoter-luciferase reporter plasmid with a vector expressing the E1A(12s) oncoprotein, a negative regulator of p300, a protein with histone acetylase activity, decreased AhR promoter activity fivefold. Overall, our results support a role for histone acetylation in the transcriptional activity of the AhR gene promoter.
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Affiliation(s)
- P M Garrison
- Department of Environmental Toxicology, Meyer Hall, One Shields Avenue, Davis, California 95616, USA
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