scholarly journals Organ-specific effects on glycolysis by the dioxin-activated aryl hydrocarbon receptor

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243842
Author(s):  
Silvia Diani-Moore ◽  
Tiago Marques Pedro ◽  
Arleen B. Rifkind
Keyword(s):  
Chick Embryo ◽  
Aryl Hydrocarbon Receptor ◽  
Environmental Pollutants ◽  
Glucose Transporters ◽  
Metabolic Effects ◽  
Mrna Levels ◽  
Aryl Hydrocarbon ◽  
Phosphorylated Akt ◽  
Thymus Atrophy ◽  
Human Primary Hepatocytes

Activation of the aryl hydrocarbon receptor (AHR) by the environmental toxin dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD) causes diverse toxicities, including thymus atrophy and hepatosteatosis. The mechanisms by which AHR activation by TCDD leads to these toxicities are not fully understood. Here we studied the effects of TCDD on a major energy pathway, glycolysis, using the chick embryo close to hatching, a well-established model for studying dioxin toxicity. We showed that 24 hr of TCDD treatment causes changes in glycolysis in both thymus and liver. In thymus glands, TCDD decreased mRNAs for glycolytic genes and glucose transporters, glycolytic indices and levels of IL7 mRNA, phosphorylated AKT (pAKT) and HIF1A, stimulators of glycolysis and promoters of survival and proliferation of thymic lymphocytes. In contrast, in liver, TCDD increased mRNA levels for glycolytic genes and glucose transporters, glycolytic endpoints and pAKT levels. Similarly, increases by TCDD in mRNA levels for glycolytic genes and glucose transporters in human primary hepatocytes showed that effects in chick embryo liver pertain also to human cells. Treatment with the glycolytic inhibitor 2-deoxy-d-glucose exacerbated the effects on thymus atrophy by TCDD, supporting a role for decreased glycolysis in thymus atrophy by TCDD, but did not prevent hepatosteatosis. NAD+ precursors abolished TCDD effects on glycolytic endpoints in both thymus and liver. In summary, we report here that dioxin disrupts glycolysis mediated energy metabolism in both thymus and liver, and that it does so in opposite ways, decreasing it in the thymus and increasing it in the liver. Further, the findings support NAD+ boosting as a strategy against metabolic effects of environmental pollutants such as dioxins.

scholarly journals Expression, Localization, and Activity of the Aryl Hydrocarbon Receptor in the Human Placenta

2018 ◽  
Vol 19 (12) ◽  
pp. 3762 ◽  
Author(s):  
Anaïs Wakx ◽  
Margaux Nedder ◽  
Céline Tomkiewicz-Raulet ◽  
Jessica Dalmasso ◽  
Audrey Chissey ◽  
...  
Keyword(s):  
Aryl Hydrocarbon Receptor ◽  
Human Placenta ◽  
Target Genes ◽  
Environmental Pollutants ◽  
Cell Fractionation ◽  
Protein Levels ◽  
Aryl Hydrocarbon ◽  
Epithelial Barriers ◽  
Expression And Activity

The human placenta is an organ between the blood of the mother and the fetus, which is essential for fetal development. It also plays a role as a selective barrier against environmental pollutants that may bypass epithelial barriers and reach the placenta, with implications for the outcome of pregnancy. The aryl hydrocarbon receptor (AhR) is one of the most important environmental-sensor transcription factors and mediates the metabolism of a wide variety of xenobiotics. Nevertheless, the identification of dietary and endogenous ligands of AhR suggest that it may also fulfil physiological functions with which pollutants may interfere. Placental AhR expression and activity is largely unknown. We established the cartography of AhR expression at transcript and protein levels, its cellular distribution, and its transcriptional activity toward the expression of its main target genes. We studied the profile of AhR expression and activity during different pregnancy periods, during trophoblasts differentiation in vitro, and in a trophoblast cell line. Using diverse methods, such as cell fractionation and immunofluorescence microscopy, we found a constitutive nuclear localization of AhR in every placental model, in the absence of any voluntarily-added exogenous activator. Our data suggest an intrinsic activation of AhR due to the presence of endogenous placental ligands.

scholarly journals A Protective Role of Aryl Hydrocarbon Receptor Repressor in Inflammation and Tumor Growth

Cancers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 589 ◽  
Author(s):  
Christoph F. A. Vogel ◽  
Yasuhiro Ishihara ◽  
Claire E. Campbell ◽  
Sarah Y. Kado ◽  
Aimy Nguyen-Chi ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Aryl Hydrocarbon Receptor ◽  
Inflammatory Responses ◽  
Environmental Pollutants ◽  
Protective Role ◽  
Potential Therapeutic Target ◽  
Embryonic Fibroblasts ◽  
Aryl Hydrocarbon ◽  
Enhancer Binding Protein

The aryl hydrocarbon receptor (AhR) is known for mediating the toxicity of environmental pollutants such as dioxins and numerous dioxin-like compounds, and is associated with the promotion of various malignancies, including lymphoma. The aryl hydrocarbon receptor repressor (AhRR), a ligand-independent, transcriptionally inactive AhR-like protein is known to repress AhR signaling through its ability to compete with the AhR for dimerization with the AhR nuclear translocator (ARNT). While AhRR effectively blocks AhR signaling, several aspects of the mechanism of AhRR’s functions are poorly understood, including suppression of inflammatory responses and its putative role as a tumor suppressor. In a transgenic mouse that overexpresses AhRR (AhRR Tg) we discovered that these mice suppress 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)- and inflammation-induced tumor growth after subcutaneous challenge of EL4 lymphoma cells. Using mouse embryonic fibroblasts (MEF) we found that AhRR overexpression suppresses the AhR-mediated anti-apoptotic response. The AhRR-mediated inhibition of apoptotic resistance was associated with a suppressed expression of interleukin (IL)-1β and cyclooxygenase (COX)-2, which was dependent on activation of protein kinase A (PKA) and the CAAT-enhancer-binding protein beta (C/EBPβ). These results provide mechanistic insights into the role of the AhRR to suppress inflammation and highlight the AhRR as a potential therapeutic target to suppress tumor growth.

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 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.

The effect of benzo[α]pyrene on expression and signaling cross talk of aryl hydrocarbon receptor and NFATc1 in mouse lung tissue

2014 ◽  
Vol 32 (7) ◽  
pp. 1246-1253 ◽  
Author(s):  
Maliheh Parsa ◽  
Seyed Nasser Ostad ◽  
Seyed Mohammad Hossein Noori Moogahi ◽  
Mohammad Bayat ◽  
Mohammad Hossein Ghahremani
Keyword(s):  
Aryl Hydrocarbon Receptor ◽  
Lung Tissue ◽  
Cross Talk ◽  
Environmental Pollutants ◽  
Lung Damage ◽  
Mouse Lung ◽  
Aryl Hydrocarbon ◽  
Embedded Blocks ◽  
Mouse Lung Tissue ◽  
Imagej Software

Objective: Polycyclic aromatic hydrocarbons (PAHs) are potent environmental pollutants. Benzo[α]pyrene (B[α]P) is the major compound of PAHs that acts by activating aryl hydrocarbon receptor (AhR) in cells. B[α]P is a known carcinogen and an immunotoxicant; however, its role with regard to nuclear factor of activated T cell (NFAT) pathway is unclear. AhR and NFAT signaling pathways have common roles in pathological functions in immunotoxicity and lung cancer. In this study, the effect of AhR activation on expression and signaling cross talk of AhR and NFATc1 pathways in mouse lung tissue has been investigated. Methods: Swiss albino mice were randomly allocated to five groups and administered with cyclosporin A (CsA) and B[α]P for seven constitutive days. Animals were then killed, and lung tissues were obtained after washing the whole blood. Paraffin-embedded blocks were prepared, and 5 µm sections were cut for histopathological and immunohistochemical assessments. The results were scored by observer and digitally analyzed using ImageJ software. Results: Our data showed that CsA administration resulted in a significant reduction of AhR expression. This effect was partly blocked in mice coadministrated with B[α]P and CsA. NFATc1 expression was also reduced in CsA-treated animals. Furthermore, CsA inhibited the pathological effects of B[α]P in mouse lung tissue. Conclusion: AhR expression is dependent on NFATc1 activation, and NFATc1 inhibition remarkably decreases AhR expression. However, it seems that total expression of NFATc1 is not dependent on AhR expression or activation. Moreover, CsA can prevent B[α]P-induced lung tissue damage, and it remarkably decreases NFATc1 expression. The results from this study point toward the molecular interactions of AhR and NFATc1 activation in lung tissue and the benefit of CsA treatment in B[α]P-induced lung damage.

scholarly journals Divergent Transcriptomic Responses to Aryl Hydrocarbon Receptor Agonists between Rat and Human Primary Hepatocytes

2009 ◽  
Vol 112 (1) ◽  
pp. 257-272 ◽  
Author(s):  
Erik A. Carlson ◽  
Colin McCulloch ◽  
Aruna Koganti ◽  
Shirlean B. Goodwin ◽  
Thomas R. Sutter ◽  
...  
Keyword(s):  
Aryl Hydrocarbon Receptor ◽  
Primary Hepatocytes ◽  
Receptor Agonists ◽  
Aryl Hydrocarbon ◽  
Transcriptomic Responses ◽  
Human Primary Hepatocytes

scholarly journals Suppression of the IgM Response by Aryl Hydrocarbon Receptor Activation in Human Primary B Cells Involves Impairment of Immunoglobulin Secretory Processes

2018 ◽  
Vol 163 (1) ◽  
pp. 319-329 ◽  
Author(s):  
Jiajun Zhou ◽  
Joseph Henriquez ◽  
Robert Crawford ◽  
Norbert Kaminski
Keyword(s):  
B Cells ◽  
Aryl Hydrocarbon Receptor ◽  
Receptor Activation ◽  
Immunoglobulin M ◽  
Mrna Levels ◽  
Significant Suppression ◽  
Regulatory Pathways ◽  
Aryl Hydrocarbon ◽  
Human B Cells ◽  
Subsequent Decrease

AbstractAryl hydrocarbon receptor (AHR) activation by 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) is well established at suppressing humoral immunity. Previous studies in mouse B cells revealed that decreased IgM production was due to a significant suppression in the mRNA levels of the immunoglobulin M components (IgH, IgJ, and Igκ chains) and subsequent decrease in IgM synthesis. In contrast, the current study shows that activation of AHR in human B cells also results in a significant suppression of the number of IgM-secreting cells, but this is not due to a decrease in the transcription or translation of IgH, IgJ, and Igκ chains. Instead, the reduced humoral response is due to the impairment of IgM secretion. This is further evidenced by an accumulation of intracellular IgM in human B cells, which indicates that activation of AHR alters distinct regulatory pathways in human and mouse B cells leading to the suppressed primary IgM response. Collectively, these results demonstrate that although AHR activation mediates suppression of humoral immune responses across many different animal species, the mechanism of action is not necessarily conserved across species.

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.    

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