scholarly journals Urolithin A Is a Dietary Microbiota-Derived Human Aryl Hydrocarbon Receptor Antagonist

2018 ◽  
Author(s):  
Gulsum E. Muku ◽  
Iain A. Murray ◽  
Juan C. Espín ◽  
Gary H. Perdew
Keyword(s):  
Gut Microbiota ◽  
Ligand Binding ◽  
Aryl Hydrocarbon Receptor ◽  
Quantitative Polymerase Chain Reaction ◽  
Health Benefits ◽  
Mrna Levels ◽  
Binding Assays ◽  
Aryl Hydrocarbon ◽  
Cyp1a1 Mrna ◽  
Competitive Ligand

Urolithins (e.g., UroA and B) are gut microbiota-derived metabolites of the natural polyphenol ellagic acid. Urolithins are associated with various health benefits, including attenuation of inflammatory signaling, anti-cancer effects and repression of lipid accumulation. The molecular mechanisms underlying the beneficial effects of urolithins remain unclear. We hypothesize that some of the human health benefits of urolithins are mediated through the aryl hydrocarbon receptor (AHR). Utilizing a cell-based reporter system, we tested urolithins for the capacity to modulate AHR activity. Cytochrome P450 1A1 (CYP1A1) mRNA levels were assessed by real-time quantitative polymerase chain reaction. Competitive ligand binding assays were performed to determine whether UroA is a direct ligand for the AHR. Subcellular AHR protein levels were examined utilizing immunoblotting analysis. AHR expression was repressed in Caco-2 cells by siRNA transfection to investigate AHR-dependency. UroA and B were able to antagonize 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced AHR-mediated transcriptional activity. Furthermore, UroA and B attenuated TCCD-mediated stimulation of CYP1A1 mRNA levels. In addition, competitive ligand binding assays characterized UroA as a direct AHR ligand. Consistent with other AHR antagonists, UroA failed to induce AHR retention in the nucleus. AHR is necessary for UroA-mediated attenuation of cytokine-induced interleukin 6 (IL6) and prostaglandin-endoperoxide synthase 2 (PTGS2) expression in Caco-2 cells. Here we identified UroA as the first dietary-derived human selective AHR antagonist produced by the gut microbiota through multi-step metabolism. Furthermore, previously reported anti-inflammatory activity of UroA may at least in part be mediated through AHR.    

scholarly journals Urolithin A Is a Dietary Microbiota-Derived Human Aryl Hydrocarbon Receptor Antagonist

Metabolites ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 86 ◽  
Author(s):  
Gulsum Muku ◽  
Iain Murray ◽  
Juan Espín ◽  
Gary Perdew
Keyword(s):  
Gut Microbiota ◽  
Ligand Binding ◽  
Aryl Hydrocarbon Receptor ◽  
Quantitative Polymerase Chain Reaction ◽  
Health Benefits ◽  
Mrna Levels ◽  
Binding Assays ◽  
Aryl Hydrocarbon ◽  
Cyp1a1 Mrna ◽  
Competitive Ligand

Urolithins (e.g., UroA and B) are gut microbiota-derived metabolites of the natural polyphenol ellagic acid. Urolithins are associated with various health benefits, including attenuation of inflammatory signaling, anti-cancer effects and repression of lipid accumulation. The molecular mechanisms underlying the beneficial effects of urolithins remain unclear. We hypothesize that some of the human health benefits of urolithins are mediated through the aryl hydrocarbon receptor (AHR). Utilizing a cell-based reporter system, we tested urolithins for the capacity to modulate AHR activity. Cytochrome P450 1A1 (CYP1A1) mRNA levels were assessed by real-time quantitative polymerase chain reaction. Competitive ligand binding assays were performed to determine whether UroA is a direct ligand for the AHR. Subcellular AHR protein levels were examined utilizing immunoblotting analysis. AHR expression was repressed in Caco-2 cells by siRNA transfection to investigate AHR-dependency. UroA and B were able to antagonize 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced AHR-mediated transcriptional activity. Furthermore, UroA and B attenuated TCDD-mediated stimulation of CYP1A1 mRNA levels. In addition, competitive ligand binding assays characterized UroA as a direct AHR ligand. Consistent with other AHR antagonists, UroA failed to induce AHR retention in the nucleus. AHR is necessary for UroA-mediated attenuation of cytokine-induced interleukin 6 (IL6) and prostaglandin-endoperoxide synthase 2 (PTGS2) expression in Caco-2 cells. Here we identified UroA as the first dietary-derived human selective AHR antagonist produced by the gut microbiota through multi-step metabolism. Furthermore, previously reported anti-inflammatory activity of UroA may at least in part be mediated through AHR.

scholarly journals Aryl hydrocarbon receptor (AHR) in the cnidarian Nematostella vectensis: comparative expression, protein interactions, and ligand binding

2013 ◽  
Vol 224 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Adam M. Reitzel ◽  
Yale J. Passamaneck ◽  
Sibel I. Karchner ◽  
Diana G. Franks ◽  
Mark Q. Martindale ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Aryl Hydrocarbon Receptor ◽  
Protein Interactions ◽  
Nematostella Vectensis ◽  
Aryl Hydrocarbon ◽  
Cnidarian Nematostella Vectensis

Activation of aryl hydrocarbon receptor by dioxin directly shifts gut microbiota in zebrafish

2019 ◽  
Vol 255 ◽  
pp. 113357 ◽  
Author(s):  
Yumiao Sun ◽  
Lizhu Tang ◽  
Yang Liu ◽  
Chenyan Hu ◽  
Bingsheng Zhou ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Aryl Hydrocarbon Receptor ◽  
Aryl Hydrocarbon

scholarly journals The UVR Filter Octinoxate Modulates Aryl Hydrocarbon Receptor Signaling in Keratinocytes via Inhibition of CYP1A1 and CYP1B1

2020 ◽  
Vol 177 (1) ◽  
pp. 188-201
Author(s):  
Sarah J Phelan-Dickinson ◽  
Brian C Palmer ◽  
Yue Chen ◽  
Lisa A DeLouise
Keyword(s):  
Aryl Hydrocarbon Receptor ◽  
Biological Effects ◽  
Mouse Skin ◽  
Daily Basis ◽  
Luciferase Reporter ◽  
Mrna Levels ◽  
Aryl Hydrocarbon ◽  
Ic50 Values ◽  
Cyp1b1 Mrna

Abstract Ultraviolet radiation (UVR) is a consistent part of the environment that has both beneficial and harmful effects on human health. UVR filters in the form of commercial sunscreens have been widely used to reduce the negative health effects of UVR exposure. Despite their benefit, literature suggests that some filters can penetrate skin and have off-target biological effects. We noted that many organic filters are hydrophobic and contain aromatic rings, making them potential modulators of Aryl hydrocarbon Receptor (AhR) signaling. We hypothesized that some filters may be able to act as agonists or antagonists on the AhR. Using a luciferase reporter cell line, we observed that the UVR filter octinoxate potentiated the ability of the known AhR ligand, 6-formylindolo[3,2-b]carbazole (FICZ), to activate the AhR. Cotreatments of keratinocytes with octinoxate and FICZ lead to increased levels of cytochrome P4501A1 (CYP1A1) and P4501B1 (CYP1B1) mRNA transcripts, in an AhR-dependent fashion. Mechanistic studies revealed that octinoxate is an inhibitor of CYP1A1 and CYP1B1, with IC50 values at approximately 1 µM and 586 nM, respectively. In vivo topical application of octinoxate and FICZ also elevated CYP1A1 and CYP1B1 mRNA levels in mouse skin. Our results show that octinoxate is able to indirectly modulate AhR signaling by inhibiting CYP1A1 and CYP1B1 enzyme function, which may have important downstream consequences for the metabolism of various compounds and skin integrity. It is important to continue studying the off-target effects of octinoxate and other UVR filters, because they are used on skin on a daily basis world-wide.

scholarly journals Recombinant expression of aryl hydrocarbon receptor for quantitative ligand-binding analysis

2009 ◽  
Vol 384 (2) ◽  
pp. 279-287 ◽  
Author(s):  
Ming Qi Fan ◽  
Alex R. Bell ◽  
David R. Bell ◽  
Sally Clode ◽  
Alwyn Fernandes ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Aryl Hydrocarbon Receptor ◽  
Recombinant Expression ◽  
Aryl Hydrocarbon ◽  
Binding Analysis

scholarly journals Aryl Hydrocarbon Receptor Activation by TCDD Modulates Expression of Extracellular Matrix Remodeling Genes during Experimental Liver Fibrosis

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Cheri L. Lamb ◽  
Giovan N. Cholico ◽  
Daniel E. Perkins ◽  
Michael T. Fewkes ◽  
Julia Thom Oxford ◽  
...  
Keyword(s):  
Gene Expression ◽  
Extracellular Matrix ◽  
Liver Injury ◽  
Aryl Hydrocarbon Receptor ◽  
Receptor Activation ◽  
Matrix Remodeling ◽  
Mrna Levels ◽  
Gelatinase Activity ◽  
Ecm Remodeling ◽  
Aryl Hydrocarbon

The aryl hydrocarbon receptor (AhR) is a soluble, ligand-activated transcription factor that mediates the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Increasing evidence implicates the AhR in regulating extracellular matrix (ECM) homeostasis. We recently reported that TCDD increased necroinflammation and myofibroblast activation during liver injury elicited by carbon tetrachloride (CCl4). However, TCDD did not increase collagen deposition or exacerbate fibrosis in CCl4-treated mice, which raises the possibility that TCDD may enhance ECM turnover. The goal of this study was to determine how TCDD impacts ECM remodeling gene expression in the liver. Male C57BL/6 mice were treated for 8 weeks with 0.5 mL/kg CCl4, and TCDD (20 μg/kg) was administered during the last two weeks. Results indicate that TCDD increased mRNA levels of procollagen types I, III, IV, and VI and the collagen processing molecules HSP47 and lysyl oxidase. TCDD also increased gelatinase activity and mRNA levels of matrix metalloproteinase- (MMP-) 3, MMP-8, MMP-9, and MMP-13. Furthermore, TCDD modulated expression of genes in the plasminogen activator/plasmin system, which regulates MMP activation, and it also increased TIMP1 gene expression. These findings support the notion that AhR activation by TCDD dysregulates ECM remodeling gene expression and may facilitate ECM metabolism despite increased liver injury.

scholarly journals Disruption of endogenous regulator homeostasis underlies the mechanism of rat CYP1A1 mRNA induction by metyrapone

1998 ◽  
Vol 331 (1) ◽  
pp. 273-281 ◽  
Author(s):  
Joanna L. HARVEY ◽  
Alan J. PAINE ◽  
Matthew C. WRIGHT
Keyword(s):  
Gene Expression ◽  
Glucocorticoid Receptor ◽  
Aryl Hydrocarbon Receptor ◽  
Culture Medium ◽  
Male Rats ◽  
Aryl Hydrocarbon ◽  
Mrna Induction ◽  
Cyp1a1 Gene ◽  
Cyp1a1 Mrna

The transcriptional induction of the cytochrome P-450 1A1 (CYP1A1) gene by xenobiotics such as polyaromatic hydrocarbons is dependent on their interaction with the aryl hydrocarbon receptor. Administration of the structurally unrelated compounds metyrapone (a cytochrome P-450 inhibitor) or dexamethasone (a glucocorticoid) to male rats does not induce hepatic CYP1A1 mRNA. However, administration of both metyrapone and dexamethasone to male rats results in the induction of hepatic CYP1A1 mRNA expression. The induction response is mimicked in vitro in cultured rat hepatocytes by the addition of metyrapone and dexamethasone to a serum-free culture medium, suggesting that these compounds act directly on the liver in vivo to effect hepatic CYP1A1 mRNA induction. An examination of the characteristics of CYP1A1 induction by metyrapone and dexamethasone in combination in vitro indicate that at least 6 h of treatment is required for detectable levels of CYP1A1 mRNA to accumulate in hepatocytes. In contrast, β-naphthoflavone, which is known to bind to the aryl hydrocarbon receptor to effect CYP1A1 gene expression, induces detectable levels of CYP1A1 mRNA within 2 h of treatment. CYP1A1 mRNA is also induced when hepatocytes are treated with metyrapone in combination with the protein synthesis inhibitor cycloheximide but not with dexamethasone in combination with cycloheximide, indicating that CYP1A1 mRNA induction is strictly dependent on the presence of metyrapone and suggesting that the metyrapone-associated induction of CYP1A1 mRNA is dependent on a loss of a constitutively expressed protein that functions to suppress CYP1A1 gene expression. The role of dexamethasone in metyrapone-associated induction of CYP1A1 is probably mediated through the glucocorticoid receptor since the glucocorticoid receptor antagonist RU486 reduces the levels of CYP1A1 mRNA induced by metyrapone and dexamethasone in combination. Increasing the levels of the photosensitizer riboflavin present in the culture medium 10-fold and exposure to light increases the levels of CYP1A1 mRNA induced by metyrapone and dexamethasone in combination in vitro, suggesting that photoactivation of inducing medium constituent(s) might be required for induction. Failure to induce CYP1A1 mRNA by co-administration of metyrapone and dexamethasone in hepatocytes cultured in a balanced salt solution with or without photoactivation indicates that induction is dependent on a photoactivated component of the culture medium and not on metyrapone or dexamethasone alone. The addition of tryptophan in the presence of riboflavin to the balanced salt solution restores CYP1A1 mRNA induction by metyrapone alone and induction is increased when medium is exposed to light, indicating that induction is dependent on tryptophan photoactivation in vitro. Metyrapone failed to compete with 2,3,7,8-tetrachlorodibenzo-p-dioxin for specific binding to the aryl hydrocarbon receptor in rat liver cytosolic fractions. These results suggest that CYP1A1 might be induced in rats by metyrapone through an indirect mechanism associated with an elevation in the level of an endogenously generated inducer such as photoactivated product(s) of tryptophan and not because of metyrapone's interacting with the aryl hydrocarbon receptor. The dependence of CYP1A1 induction on dexamethasone or cycloheximide suggests that derepression by a glucocorticoid receptor-modulated negative-acting factor of CYP1A1 gene expression might be critical to induction by metyrapone.

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