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1.
Aquat Toxicol ; 233: 105794, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33662880

RESUMO

Polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are environmental contaminants known to impact cardiac development, a key step in the embryonic development of most animals. To date, little is understood of the molecular mechanism driving the observed cardiac defects in exposed fishes. The literature shows PCB & TCDD derived cardiac defects are concurrent with, but not caused by, expression of cyp1A, due to activation of the aryl hydrocarbon receptor (AhR) gene activation pathway. However, in this study, detailed visualization of fish hearts exposed to PCBs and TCDD show that, in addition to a failure of cardiac looping in early heart development, the inner endocardial lining of the heart fails to maintain proper cell adhesion and tissue integrity. The resulting gap between the endocardium and myocardium in both zebrafish and Atlantic sturgeon suggested functional faults in endothelial adherens junction formation. Thus, we explored the molecular mechanism triggering cardiac defects using immunohistochemistry to identify the location and phosphorylation state of key regulatory and adhesion molecules. We hypothesized that PCB and TCDD activates AhR, phosphorylating Src, which then phosphorylates the endothelial adherens junction protein, VEcadherin. When phosphorylated, VEcadherin dimers, found in the endocardium and vasculature, separate, reducing tissue integrity. In zebrafish, treatment with PCB and TCDD contaminants leads to higher phosphorylation of VEcadherin in cardiac tissue suggesting that these cells have reduced connectivity. Small molecule inhibition of Src phosphorylation prevents contaminant stimulated phosphorylation of VEcadherin and rescues both cardiac function and gross morphology. Atlantic sturgeon hearts show parallels to contaminant exposed zebrafish cardiac phenotype at the tissue level. These data suggest that the mechanism for PCB and TCDD action in the heart is, in part, distinct from the canonical mechanism described in the literature and that cardiac defects are impacted by this nongenomic mechanism.


Assuntos
Embrião não Mamífero/efeitos dos fármacos , Coração/efeitos dos fármacos , Bifenilos Policlorados/toxicidade , Dibenzodioxinas Policloradas/toxicidade , Receptores de Hidrocarboneto Arílico/metabolismo , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/metabolismo , Animais , Sinergismo Farmacológico , Embrião não Mamífero/anormalidades , Embrião não Mamífero/metabolismo , Desenvolvimento Embrionário/efeitos dos fármacos , Coração/embriologia , Miocárdio/metabolismo , Peixe-Zebra/crescimento & desenvolvimento
2.
Chem Biol Interact ; 338: 109428, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33647240

RESUMO

Camostat mesylate, a potent inhibitor of the human transmembrane protease, serine 2 (TMPRSS2), is currently under investigation for its effectiveness in COVID-19 patients. For its safe application, the risks of camostat mesylate to induce pharmacokinetic drug-drug interactions with co-administered drugs should be known. We therefore tested in vitro the potential inhibition of important efflux (P-glycoprotein (P-gp, ABCB1), breast cancer resistance protein (BCRP, ABCG2)), and uptake transporters (organic anion transporting polypeptides OATP1B1, OATP1B3, OATP2B1) by camostat mesylate and its active metabolite 4-(4-guanidinobenzoyloxy)phenylacetic acid (GBPA). Transporter inhibition was evaluated using fluorescent probe substrates in transporter over-expressing cell lines and compared to the respective parental cell lines. Moreover, possible mRNA induction of pharmacokinetically relevant genes regulated by the nuclear pregnane X receptor (PXR) and aryl hydrocarbon receptor (AhR) was analysed in LS180 cells by quantitative real-time PCR. The results of our study for the first time demonstrated that camostat mesylate and GBPA do not relevantly inhibit P-gp, BCRP, OATP1B1 or OATP1B3. Only OATP2B1 was profoundly inhibited by GBPA with an IC50 of 11 µM. Induction experiments in LS180 cells excluded induction of PXR-regulated genes such as cytochrome P450 3A4 (CYP3A4) and ABCB1 and AhR-regulated genes such as CYP1A1 and CYP1A2 by camostat mesylate and GBPA. Together with the summary of product characteristics of camostat mesylate indicating no inhibition of CYP1A2, 2C9, 2C19, 2D6, and 3A4 in vitro, our data suggest a low potential of camostat mesylate to act as a perpetrator in pharmacokinetic drug-drug interactions. Only inhibition of OATP2B1 by GBPA warrants further investigation.


Assuntos
Interações Medicamentosas , Ésteres/metabolismo , Guanidinas/metabolismo , Inibidores de Serino Proteinase/metabolismo , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/antagonistas & inibidores , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Citocromo P-450 CYP1A1/genética , Citocromo P-450 CYP1A1/metabolismo , Citocromo P-450 CYP3A/genética , Citocromo P-450 CYP3A/metabolismo , Ésteres/química , Ésteres/farmacologia , Guanidinas/química , Guanidinas/farmacologia , Humanos , Transportadores de Ânions Orgânicos/antagonistas & inibidores , Transportadores de Ânions Orgânicos/metabolismo , Receptor de Pregnano X/genética , Receptor de Pregnano X/metabolismo , RNA Mensageiro/metabolismo , Receptores de Hidrocarboneto Arílico/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Serina Endopeptidases/química , Serina Endopeptidases/metabolismo , Inibidores de Serino Proteinase/química , Inibidores de Serino Proteinase/farmacologia
3.
Int J Mol Sci ; 22(4)2021 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-33562472

RESUMO

The metabolism of tryptophan is intimately associated with the differential regulation of diverse physiological processes, including in the regulation of responses to severe acute respiratory syndrome, coronavirus-2 (SARS-CoV-2) infection that underpins the COVID-19 pandemic. Two important products of tryptophan metabolism, viz kynurenine and interleukin (IL)4-inducible1 (IL41)-driven indole 3 pyruvate (I3P), activate the aryl hydrocarbon receptor (AhR), thereby altering the nature of immune responses to SARS-CoV-2 infection. AhR activation dysregulates the initial pro-inflammatory cytokines production driven by neutrophils, macrophages, and mast cells, whilst AhR activation suppresses the endogenous antiviral responses of natural killer cells and CD8+ T cells. Such immune responses become further dysregulated by the increased and prolonged pro-inflammatory cytokine suppression of pineal melatonin production coupled to increased gut dysbiosis and gut permeability. The suppression of pineal melatonin and gut microbiome-derived butyrate, coupled to an increase in circulating lipopolysaccharide (LPS) further dysregulates the immune response. The AhR mediates its effects via alterations in the regulation of mitochondrial function in immune cells. The increased risk of severe/fatal SARS-CoV-2 infection by high risk conditions, such as elderly age, obesity, and diabetes are mediated by these conditions having expression levels of melatonin, AhR, butyrate, and LPS that are closer to those driven by SARS-CoV-2 infection. This has a number of future research and treatment implications, including the utilization of melatonin and nutraceuticals that inhibit the AhR, including the polyphenols, epigallocatechin gallate (EGCG), and resveratrol.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Receptores de Hidrocarboneto Arílico/metabolismo , /fisiologia , Triptofano/metabolismo , Animais , /fisiopatologia , Humanos , Inflamação/complicações , Inflamação/metabolismo , Inflamação/fisiopatologia , /fisiopatologia
4.
Ecotoxicol Environ Saf ; 210: 111857, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33421718

RESUMO

OBJECTIVES: Benzo(a)pyrene (BaP) is a ubiquitous air pollutants, and BaP exposure leads to a risk of respiratory diseases. The oversecretion of airway mucus and high expression of mucin 5AC (MUC5AC) are associated with common respiratory disorders caused by air pollution. We aimed to investigate the effect of BaP on MUC5AC expression, especially the mechanisms by which BaP induces MUC5AC gene expression. METHODS: The human airway epithelial cell NCI-H292 was used to test the effects of BaP on the expression of MUC5AC in vitro. MUC5AC mRNA and protein expression were assessed with real-time quantitative PCR, immunochemistry, and western blotting. A luciferase assay was conducted to detect the activity of the promoter. The total cellular ROS and mitochondrial ROS were measured by corresponding probes. Small-interfering RNAs were used for gene silencing. AhR-overexpressing cell lines were constructed by transfection with AhR overexpression lentivirus. RESULTS: We found that BaP stimulation upregulated the MUC5AC mRNA and protein levels and activated the ERK pathway. Suppressing ERK with U0126 (an ERK inhibitor) or knocking down ERK with siRNA decreased BaP-induced MUC5AC expression. The luciferase activity transfected with the MUC5AC promoter and cAMP-response element (CRE) was increased after BaP treatment, whereas CREB siRNA suppressed the BaP-induced overexpression of MUC5AC. In addition, BaP increased mitochondrial ROS production, and Mito-TEMP, a mitochondrial ROS inhibitor, inhibited BaP-induced MUC5AC expression and ERK activation. BaP increased the mRNA levels of CYP1A1 and CYP1B1, while Alizarin, a CYP1s inhibitor, suppressed the effects of BaP, including the MUC5AC overexpression, ERK activation and mitochondrial ROS generation. BaP induced the translocation of aryl hydrocarbon receptor (AhR) from the cytoplasm to the nucleus. SiRNA-mediated knockdown or chemical inhibition of AhR decreased the BaP-induced expression of MUC5AC, while the overexpression of AhR significantly enhanced the BaP-induced expression of MUC5AC. ITE, an endogenous AhR ligand, also upregulated the mRNA and protein expression of MUC5AC. Furthermore, resveratrol treatment inhibited the BaP-induced MUC5AC overexpression, AhR translocation, mitochondrial ROS production and ERK pathway activation. CONCLUSION: Here, we highlighted the crucial role of AhR/mitochondrial ROS/ERK pathway activation in BaP-induced MUC5AC overexpression and identified resveratrol as a promising drug to reduce BaP-induced MUC5AC overexpression.


Assuntos
Poluentes Atmosféricos/toxicidade , Benzo(a)pireno/toxicidade , Células Epiteliais/efeitos dos fármacos , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Linhagem Celular , Células Epiteliais/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/genética , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Humanos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mucina-5AC/genética , Mucina-5AC/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Receptores de Hidrocarboneto Arílico/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Sistema Respiratório/citologia , Transdução de Sinais/efeitos dos fármacos
5.
Nat Commun ; 12(1): 213, 2021 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-33431899

RESUMO

High-fat diet (HFD) decreases insulin sensitivity. How high-fat diet causes insulin resistance is largely unknown. Here, we show that lean mice become insulin resistant after being administered exosomes isolated from the feces of obese mice fed a HFD or from patients with type II diabetes. HFD altered the lipid composition of exosomes from predominantly phosphatidylethanolamine (PE) in exosomes from lean animals (L-Exo) to phosphatidylcholine (PC) in exosomes from obese animals (H-Exo). Mechanistically, we show that intestinal H-Exo is taken up by macrophages and hepatocytes, leading to inhibition of the insulin signaling pathway. Moreover, exosome-derived PC binds to and activates AhR, leading to inhibition of the expression of genes essential for activation of the insulin signaling pathway, including IRS-2, and its downstream genes PI3K and Akt. Together, our results reveal HFD-induced exosomes as potential contributors to the development of insulin resistance. Intestinal exosomes thus have potential as broad therapeutic targets.


Assuntos
Dieta Hiperlipídica , Exossomos/metabolismo , Resistência à Insulina/genética , Fosfatidilcolinas/metabolismo , Regulação para Cima/genética , Tecido Adiposo/metabolismo , Animais , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Dislipidemias/complicações , Dislipidemias/genética , Dislipidemias/patologia , Células Epiteliais/metabolismo , Fígado Gorduroso/complicações , Fígado Gorduroso/genética , Fígado Gorduroso/patologia , Fezes , Regulação da Expressão Gênica , Intolerância à Glucose , Proteínas de Fluorescência Verde/metabolismo , Humanos , Insulina/metabolismo , Interleucina-6/sangue , Intestinos/citologia , Lipídeos/química , Fígado/metabolismo , Fígado/patologia , Ativação de Macrófagos , Camundongos Endogâmicos C57BL , Receptores de Hidrocarboneto Arílico/metabolismo , Transdução de Sinais , Tetraspanina 30/metabolismo , Fator de Necrose Tumoral alfa/sangue
6.
Nat Commun ; 12(1): 290, 2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33436590

RESUMO

The environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) causes hepatic toxicity associated with prominent lipid accumulation in humans. Here, the authors report that the lysosomal copper transporter SLC46A3 is induced by TCDD and underlies the hepatic lipid accumulation in mice, potentially via effects on mitochondrial function. SLC46A3 was localized to the lysosome where it modulated intracellular copper levels. Forced expression of hepatic SLC46A3 resulted in decreased mitochondrial membrane potential and abnormal mitochondria morphology consistent with lower copper levels. SLC46A3 expression increased hepatic lipid accumulation similar to the known effects of TCDD exposure in mice and humans. The TCDD-induced hepatic triglyceride accumulation was significantly decreased in Slc46a3-/- mice and was more pronounced when these mice were fed a high-fat diet, as compared to wild-type mice. These data are consistent with a model where lysosomal SLC46A3 induction by TCDD leads to cytosolic copper deficiency resulting in mitochondrial dysfunction leading to lower lipid catabolism, thus linking copper status to mitochondrial function, lipid metabolism and TCDD-induced liver toxicity.


Assuntos
Proteínas de Transporte de Cobre/metabolismo , Cobre/metabolismo , Citosol/metabolismo , Homeostase , Lisossomos/metabolismo , Transportador de Folato Acoplado a Próton/metabolismo , Animais , Proteínas de Transporte de Cobre/genética , Citosol/efeitos dos fármacos , Proteínas de Fluorescência Verde/metabolismo , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Hepatócitos/ultraestrutura , Homeostase/efeitos dos fármacos , Íons , Fígado/metabolismo , Lisossomos/efeitos dos fármacos , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Modelos Biológicos , Dibenzodioxinas Policloradas/toxicidade , Transportador de Folato Acoplado a Próton/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Especificidade por Substrato/efeitos dos fármacos , Superóxido Dismutase/metabolismo , Triglicerídeos/metabolismo
7.
Life Sci ; 268: 119015, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33412215

RESUMO

AIMS: Metformin improves vascular function in obese type 2 diabetic patients. 8-Oxoguanine glycosylase (OGG1) is a main DNA glycosylase that is involved in vascular complications in various diseases. However, whether metformin suppresses endothelial reactive species oxygen production via the OGG1 pathway is unclear. MAIN METHODS: Human umbilical vein endothelial cells (HUVECs) were exposed to HG (high glucose) with or without metformin. OGG1 and AMPKα levels were measured after metformin treatment, while HG-induced ROS were measured by a DHE probe. KEY FINDINGS: Metformin reduced HG-induced endothelial ROS by upregulating OGG1. Additionally, OGG1 protein expression was dependent on its mRNA stability, which was reversed by genetic inhibition of AMPKα and Lin-28. Furthermore, the effect of OGG1 on HG-induced ROS was partially dependent on the AHR/Nrf2 pathway in HUVECs. SIGNIFICANCE: These results suggested that metformin modulated HG-induced endothelial ROS via the AMPKα/Lin-28/OGG1 pathway.


Assuntos
DNA Glicosilases/metabolismo , Metformina/farmacologia , Proteínas de Ligação a RNA/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Proteínas Quinases Ativadas por AMP/antagonistas & inibidores , Proteínas Quinases Ativadas por AMP/genética , Proteínas Quinases Ativadas por AMP/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , DNA Glicosilases/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Glucose/farmacologia , Células Endoteliais da Veia Umbilical Humana , Humanos , Fator 2 Relacionado a NF-E2/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Fosforilação , Estabilidade de RNA , Receptores de Hidrocarboneto Arílico/metabolismo
8.
Ecotoxicol Environ Saf ; 211: 111947, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33503546

RESUMO

The chicken (Gallus gallus), which has three aryl hydrocarbon receptor (AHR) isoforms (ckAHR1, ckAHR2, and ckAHR1ß) and two AHR nuclear translocator (ARNT) isoforms (ckARNT1 and ckARNT2), is highly sensitive to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and can serve as an avian model to gain an understanding of the mechanism underlying dioxin toxicity. To elucidate the mechanism of TCDD-induced immunotoxicity in avian species, we treated chicken embryos in ovo with graded concentrations of TCDD (1.5, 2.5, 3.0, 3.3, 3.5, and 4.0 µM). Initially, we measured mRNA expression levels of ckAHR and ckARNT isoforms and analyzed the T cell populations and transcriptome in the thymuses of TCDD-treated chicken embryos. Quantitative polymerase chain reaction analysis revealed that mRNA expressions of ckAHR1 and ckARNT2 were dominant in the thymus. Severe weight loss and thymus atrophy were observed in the TCDD-treated embryos. Immunophenotyping analyses demonstrated significant increases in CD4+CD8-CD25+ and CD4+CD8+CD25+ regulatory T cells (Tregs) populations following TCDD exposure, suggesting that TCDD suppresses T cell-mediated immune responses in chicken embryos. In addition, thymic transcriptome analyses intimated that alteration of the signaling pathways related to erb-b2 receptor tyrosine kinase 4 (ERBB4) and wnt family member 5A (WNT5A), and bone morphogenetic protein (BMP) may be associated with the TCDD-induced thymus atrophy. We also observed significantly altered expression levels of genes including interleukine 13 receptor subunit alpha 2 (IL13RA2), transforming growth factor beta 1 (TGFß1), collagen type III alpha 1 chain (COL3A1), and collagen type IX alpha 3 chain (COL9A3), implying immunosuppression, fibrosis development, and collagen deposition. Collectively, these findings suggest that TCDD exposure activates the ckAHR1-ckARNT2 signaling pathway and suppresses immune responses through the prompted differentiation to CD4+CD8-CD25+ and CD4+CD8+CD25+ Tregs and altered expressions of immune-related genes in the thymus of chicken embryos.


Assuntos
Poluentes Ambientais/toxicidade , Dibenzodioxinas Policloradas/toxicidade , Animais , Translocador Nuclear Receptor Aril Hidrocarboneto/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos , Linfócitos T CD8-Positivos/metabolismo , Diferenciação Celular , Embrião de Galinha , Galinhas/metabolismo , Sistema Imunitário/efeitos dos fármacos , Isoformas de Proteínas/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Transdução de Sinais , Linfócitos T , Transcriptoma
9.
Int J Mol Sci ; 22(2)2021 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-33445793

RESUMO

Poisoning by high concentrations of dioxin and its related compounds manifests variable toxic symptoms such as general malaise, chloracne, hyperpigmentation, sputum and cough, paresthesia or numbness of the extremities, hypertriglyceridemia, perinatal abnormalities, and elevated risks of cancer-related mortality. Such health hazards are observed in patients with Yusho (oil disease in Japanese) who had consumed rice bran oil highly contaminated with 2,3,4,7,8-pentachlorodibenzofuran, polychlorinated biphenyls, and polychlorinated quaterphenyls in 1968. The blood concentrations of these congeners in patients with Yusho remain extremely elevated 50 years after onset. Dioxins exert their toxicity via aryl hydrocarbon receptor (AHR) through the generation of reactive oxygen species (ROS). In this review article, we discuss the pathogenic implication of AHR in dioxin-induced health hazards. We also mention the potential therapeutic use of herbal drugs targeting AHR and ROS in patients with Yusho.


Assuntos
Dioxinas/envenenamento , Porfirias/induzido quimicamente , Porfirias/metabolismo , Receptores de Hidrocarboneto Arílico/metabolismo , Animais , Humanos , Espécies Reativas de Oxigênio/metabolismo , Óleo de Farelo de Arroz/efeitos adversos
10.
Am J Physiol Cell Physiol ; 320(2): C240-C249, 2021 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-33406025

RESUMO

Chronic kidney disease (CKD) is associated with a substantial increased risk of cardiovascular disease. There is growing evidence that uremic metabolites, which accumulate in the blood with CKD, have detrimental impacts on endothelial cell health and function. However, the molecular mechanisms by which uremic metabolites negatively impact endothelial cell biology are not fully understood. In this study, activation of the aryl hydrocarbon receptor (AHR) via indoxyl sulfate, a known uremic metabolite, was found to impair endothelial cell tube formation and proliferation but not migratory function. Moreover, aortic ring cultures treated with indoxyl sulfate also exhibited decreased sprouting and high AHR activation. Next, genetic knockdown of the AHR using shRNA was found to rescue endothelial cell tube formation, proliferation, and aortic ring sprouting. Similarly, pharmacological AHR antagonism using resveratrol and CH223191 were also found to rescue angiogenesis in cell and aortic ring cultures. Finally, a constitutively active AHR (CAAHR) vector was generated and used to confirm AHR-specific effects. Expression of the CAAHR recapitulated the impaired tube formation and proliferation in cultured endothelial cells and decreased sprouting in aortic ring cultures. Taken together, these data define the impact of AHR activation on angiogenesis and highlight the potential for therapeutic AHR antagonists, which may improve angiogenesis in the context of CKD and cardiovascular disease.


Assuntos
Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/metabolismo , Indicã/farmacologia , Neovascularização Fisiológica/efeitos dos fármacos , Neovascularização Fisiológica/fisiologia , Receptores de Hidrocarboneto Arílico/metabolismo , Animais , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Técnicas de Cultura de Órgãos
11.
Chemosphere ; 263: 128086, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33297084

RESUMO

Polychlorinated dioxins and dibenzofurans (PCDD/Fs) are highly toxic contaminants that are strictly regulated and monitored in the environment and food to reduce human exposure. Recently, the increasing occurrence of polybrominated dioxins and dibenzofurans (PBDD/Fs) in the environment is raising concerns about the impact on human health by the combined exposure to chlorinated and brominated analogues of dioxins. Toxicological properties of PBDD/Fs relative to PCDD/Fs have not been firmly established, and brominated dioxins are not included in routine monitoring programs. In this study, we set out to determine human-relevant congener-specific potency values for a range of brominated and chlorinated dioxin congeners, based on their aryl hydrocarbon receptor (AhR)-mediated mode of toxic action. Transactivation of the AhR was measured using dioxin-responsive (DR) CALUX reporter gene assays. Because of known species-differences in dioxin-mediated toxicity, we developed and used a HepG2 human liver cell-based DR human CALUX assay that is a variant of the rodent-based DR CALUX. The assay was found to be highly inducible and stable, with low variations between independent measurements. Using both DR CALUX assays in an automated high-throughput mode we found that overall PBDD/Fs were as potent as PCDD/Fs in inducing AhR transactivation, but congener-specific differences were observed. We also observed species-specific differences in sensitivity and potency when comparing DR human REP values to those obtained in the rat-based DR CALUX. Finally, we observed significant differences between WHO-TEF values and DR human REP values, suggesting that actual WHO-TEF values may underestimate the hazards associated with exposure of humans to dioxins.


Assuntos
Dioxinas , Dibenzodioxinas Policloradas , Animais , Dibenzofuranos , Dibenzofuranos Policlorados , Dioxinas/toxicidade , Genes Reporter , Humanos , Dibenzodioxinas Policloradas/toxicidade , Ratos , Receptores de Hidrocarboneto Arílico/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Ativação Transcricional
12.
Chemosphere ; 268: 129343, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33359989

RESUMO

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants associated with adverse human effects including cancer, and the aryl hydrocarbon receptor (AhR) is a key ligand-activated transcription factor mediating their toxicity. However, there is presently a lack of data on AhR potencies of PAHs. Simple, transparent, interpretable and predictive quantitative structure-activity relationship (QSAR) models are helpful, especially with the consideration of freely dissolved concentrations linked to bioavailability. Here, QSAR models on AhR-mediated luciferase activity of PAHs were developed with nominal median effect concentrations (EC50, nom) and freely dissolved concentration (EC50, free) as endpoints, and quantum chemical and Dragon descriptors as predictor variables. Results indicated that only the EC50, free model met the acceptable criteria of QSAR model (determination coefficient (R2) > 0.600, leave-one-out cross validation (QLOO2) > 0.500, and external validation coefficient (QEXT2) > 0.500), implying that it has good goodness-of-fit, robustness and external predictive power. Molecular polarizability and aromaticity index reflecting the partition behavior and intermolecular interactions can effectively predict AhR-mediated potencies of PAHs. The results highlight the necessity of adoption of the freely dissolved concentration in the QSAR modeling and more in silico models need to be further developed for different animal models (in vivo or in vitro).


Assuntos
Poluentes Ambientais , Hidrocarbonetos Policíclicos Aromáticos , Animais , Humanos , Luciferases , Hidrocarbonetos Policíclicos Aromáticos/análise , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Relação Quantitativa Estrutura-Atividade , Receptores de Hidrocarboneto Arílico/metabolismo
13.
Chemosphere ; 262: 128356, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182092

RESUMO

Polybrominated diphenyl ethers (PBDEs) are often suspected to activate the signal transduction pathway of aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor, for the induction of toxicity. Hence, the binding property of PBDEs with AhR is assumed to be associated with the ligand-dependent activation of AhR that may introduce many drug-metabolizing enzymes of genes encoding. However, the binding mechanism and the structural effect of PBDEs on their binding properties of AhR still need to be unraveled for toxicology research. A comprehensive study of the PBDEs-AhR binding mechanism was investigated using an integrated molecular modeling approach with two-dimensional quantitative structure-activity relationships (2D-QSAR), three-dimensional QSAR (3D-QSAR), and molecular docking simulation. Molecular docking revealed the differences in binding domains among 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-AhR complex and two PBDE-AhR complexes. A 2D-QSAR model was developed to analyze the overall structural effects of PBDEs on the binding affinity of AhR. It provided an insight into major physico-chemical properties by multiple linear regression based on genetic algorithm with reasonable results. The 3D-QSAR modeling discovered the detailed interaction features of binding sites, configurations and interaction fields of AhR with different PBDE ligands. This study demonstrated that the descriptors of Smin69 and MoRSEC15 were related to electronic properties and had a great effect on the relative binding affinities. The position of Br substitutions exhibited a significant influence on the interactions between AhR and PBDEs, including halogen interaction, π-S interaction, π-π stacking interaction, and hydrophobic effect. This integrated molecular modeling approach provided a comprehensive analysis of the structural effects of PBDEs on their binding properties with AhR at molecular level.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/química , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Éteres Difenil Halogenados/química , Éteres Difenil Halogenados/metabolismo , Dibenzodioxinas Policloradas , Relação Quantitativa Estrutura-Atividade , Receptores de Hidrocarboneto Arílico/química , Receptores de Hidrocarboneto Arílico/metabolismo , Sítios de Ligação , Interações Hidrofóbicas e Hidrofílicas , Ligantes , Modelos Moleculares , Simulação de Acoplamento Molecular , Dibenzodioxinas Policloradas/química , Dibenzodioxinas Policloradas/metabolismo , Transdução de Sinais
14.
Int J Mol Sci ; 21(24)2020 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-33348596

RESUMO

Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a potent ligand for AhR and a known carcinogen. While AhR activation by TCDD leads to significant immunosuppression, how this translates into carcinogenic signal is unclear. Recently, we demonstrated that activation of AhR by TCDD in naïve C57BL6 mice leads to massive induction of myeloid derived-suppressor cells (MDSCs). In the current study, we investigated the role of the gut microbiota in TCDD-mediated MDSC induction. TCDD caused significant alterations in the gut microbiome, such as increases in Prevotella and Lactobacillus, while decreasing Sutterella and Bacteroides. Fecal transplants from TCDD-treated donor mice into antibiotic-treated mice induced MDSCs and increased regulatory T-cells (Tregs). Injecting TCDD directly into antibiotic-treated mice also induced MDSCs, although to a lesser extent. These data suggested that TCDD-induced dysbiosis plays a critical role in MDSC induction. Interestingly, treatment with TCDD led to induction of MDSCs in the colon and undetectable levels of cysteine. MDSCs suppressed T cell proliferation while reconstitution with cysteine restored this response. Lastly, blocking CXC chemokine receptor 2 (CXCR2) impeded TCDD-mediated MDSC induction. Our data demonstrate that AhR activation by TCDD triggers dysbiosis which, in turn, regulates, at least in part, induction of MDSCs.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Disbiose/induzido quimicamente , Microbioma Gastrointestinal/efeitos dos fármacos , Células Supressoras Mieloides/metabolismo , Dibenzodioxinas Policloradas/efeitos adversos , Receptores de Hidrocarboneto Arílico/metabolismo , Receptores de Interleucina-8B/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Antibacterianos/farmacologia , Células Cultivadas , DNA Bacteriano/genética , Transplante de Microbiota Fecal/métodos , Fezes/microbiologia , Feminino , Microbioma Gastrointestinal/genética , Camundongos , Camundongos Endogâmicos C57BL , Filogenia , Linfócitos T Reguladores/imunologia
15.
Int J Mol Sci ; 21(24)2020 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-33348604

RESUMO

Increasingly, the aryl hydrocarbon receptor (AHR) is being recognized as a sensor for endogenous and pseudo-endogenous metabolites, and in particular microbiota and host generated tryptophan metabolites. One proposed explanation for this is the role of the AHR in innate immune signaling within barrier tissues in response to the presence of microorganisms. A number of cytokine/chemokine genes exhibit a combinatorial increase in transcription upon toll-like receptors and AHR activation, supporting this concept. The AHR also plays a role in the enhanced differentiation of intestinal and dermal epithelium leading to improved barrier function. Importantly, from an evolutionary perspective many of these tryptophan metabolites exhibit greater activation potential for the human AHR when compared to the rodent AHR. These observations underscore the importance of the AHR in barrier tissues and may lead to pharmacologic therapeutic intervention.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Microbioma Gastrointestinal/fisiologia , Receptores de Hidrocarboneto Arílico/metabolismo , Transdução de Sinais/fisiologia , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/agonistas , Fatores de Transcrição Hélice-Alça-Hélice Básicos/antagonistas & inibidores , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Citocromo P-450 CYP1A1/metabolismo , Citocinas/metabolismo , Humanos , Ligantes , Camundongos , Camundongos Knockout , Receptores de Hidrocarboneto Arílico/agonistas , Receptores de Hidrocarboneto Arílico/antagonistas & inibidores , Receptores de Hidrocarboneto Arílico/genética , Triptofano/metabolismo
16.
Int J Mol Sci ; 21(24)2020 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-33321923

RESUMO

Skin barrier dysfunction, including reduced filaggrin (FLG) and loricrin (LOR) expression, plays a critical role in atopic dermatitis (AD) development. Since aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor, mediates keratinocyte differentiation, it is a potential target for AD treatment. Recently, clinical studies have shown that tapinarof, an AHR modulator, attenuated the development of AD. To examine the molecular mechanism involved in this, we analyzed tapinarof-treated normal human epidermal keratinocytes (NHEKs). Tapinarof upregulated FLG and LOR mRNA and protein expression in an AHR-dependent manner. Tapinarof also induced the secretion of IL-24, a cytokine that activates Janus kinase (JAK)-signal transducer and activator of transcription (STAT), leading to the downregulation of FLG and LOR expression. Knockdown of either IL-24 or STAT3 expression by small interfering RNA (siRNA) transfection augmented the upregulation of FLG and LOR expression induced by tapinarof, suggesting that inhibition of the IL-24/STAT3 axis during AHR activation supports the improvement of skin barrier dysfunction. Furthermore, tapinarof alone could restore the downregulation of FLG and LOR expression induced by IL-4, a key cytokine of AD, and its combination with JAK inhibitors enhanced this effect. These findings provide a new strategy for treating AD using AHR modulators and JAK inhibitors.


Assuntos
Diferenciação Celular , Dermatite Atópica/metabolismo , Interleucinas/metabolismo , Queratinócitos/metabolismo , Receptores de Hidrocarboneto Arílico/metabolismo , Resorcinóis/farmacologia , Estilbenos/farmacologia , Células Cultivadas , Humanos , Interleucinas/genética , Proteínas de Filamentos Intermediários/genética , Proteínas de Filamentos Intermediários/metabolismo , Janus Quinases/metabolismo , Queratinócitos/citologia , Queratinócitos/efeitos dos fármacos , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Fator de Transcrição STAT3/genética , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais
17.
Int J Mol Sci ; 22(1)2020 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-33374508

RESUMO

The aryl hydrocarbon receptor (AHR) has been studied for over 40 years, yet our understanding of this ligand-activated transcription factor remains incomplete. Each year, novel findings continually force us to rethink the role of the AHR in mammalian biology. The AHR has historically been studied within the context of potent activation via AHR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), with a focus on how the AHR mediates TCDD toxicity. Research has subsequently revealed that the AHR is actively involved in distinct physiological processes ranging from the development of the liver and reproductive organs, to immune system function and wound healing. More recently, the AHR was implicated in the regulation of energy metabolism and is currently being investigated as a potential therapeutic target for obesity. In this review, we re-trace the steps through which the early toxicological studies of TCDD led to the conceptual framework for the AHR as a potential therapeutic target in metabolic disease. We additionally discuss the key discoveries that have been made concerning the role of the AHR in energy metabolism, as well as the current and future directions of the field.


Assuntos
Metabolismo Energético , Receptores de Hidrocarboneto Arílico/metabolismo , Animais , Dioxinas/efeitos adversos , Modelos Animais de Doenças , Suscetibilidade a Doenças , Desenvolvimento de Medicamentos , Metabolismo Energético/genética , Regulação da Expressão Gênica , Humanos , Ligantes , Camundongos Transgênicos , Terapia de Alvo Molecular , Obesidade/tratamento farmacológico , Obesidade/etiologia , Obesidade/metabolismo , Dibenzodioxinas Policloradas/efeitos adversos , Receptores de Hidrocarboneto Arílico/antagonistas & inibidores , Receptores de Hidrocarboneto Arílico/genética , Síndrome de Emaciação/etiologia , Síndrome de Emaciação/metabolismo
18.
Int J Mol Sci ; 22(1)2020 Dec 25.
Artigo em Inglês | MEDLINE | ID: mdl-33375613

RESUMO

This article reviews the dynamic interactions of the tumour microenvironment, highlighting the roles of acetyl-CoA and melatonergic pathway regulation in determining the interactions between oxidative phosphorylation (OXPHOS) and glycolysis across the array of cells forming the tumour microenvironment. Many of the factors associated with tumour progression and immune resistance, such as yin yang (YY)1 and glycogen synthase kinase (GSK)3ß, regulate acetyl-CoA and the melatonergic pathway, thereby having significant impacts on the dynamic interactions of the different types of cells present in the tumour microenvironment. The association of the aryl hydrocarbon receptor (AhR) with immune suppression in the tumour microenvironment may be mediated by the AhR-induced cytochrome P450 (CYP)1b1-driven 'backward' conversion of melatonin to its immediate precursor N-acetylserotonin (NAS). NAS within tumours and released from tumour microenvironment cells activates the brain-derived neurotrophic factor (BDNF) receptor, TrkB, thereby increasing the survival and proliferation of cancer stem-like cells. Acetyl-CoA is a crucial co-substrate for initiation of the melatonergic pathway, as well as co-ordinating the interactions of OXPHOS and glycolysis in all cells of the tumour microenvironment. This provides a model of the tumour microenvironment that emphasises the roles of acetyl-CoA and the melatonergic pathway in shaping the dynamic intercellular metabolic interactions of the various cells within the tumour microenvironment. The potentiation of YY1 and GSK3ß by O-GlcNAcylation will drive changes in metabolism in tumours and tumour microenvironment cells in association with their regulation of the melatonergic pathway. The emphasis on metabolic interactions across cell types in the tumour microenvironment provides novel future research and treatment directions.


Assuntos
Neoplasias/patologia , Microambiente Tumoral , Acetilcoenzima A/metabolismo , Fatores Etários , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Biologia Computacional , Humanos , Imunomodulação , Melatonina/metabolismo , Redes e Vias Metabólicas , Mitocôndrias/metabolismo , Modelos Biológicos , Neoplasias/etiologia , Neoplasias/metabolismo , Especificidade de Órgãos/genética , Especificidade de Órgãos/imunologia , Receptores de Hidrocarboneto Arílico/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Sirtuínas/metabolismo , Microambiente Tumoral/genética , Microambiente Tumoral/imunologia
19.
PLoS One ; 15(12): e0243842, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33320884

RESUMO

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.


Assuntos
Dioxinas/toxicidade , Glicólise/efeitos dos fármacos , Especificidade de Órgãos/efeitos dos fármacos , Receptores de Hidrocarboneto Arílico/metabolismo , Adulto , Animais , Células Cultivadas , Embrião de Galinha , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Glucose/metabolismo , Glicólise/genética , Humanos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Niacinamida/análogos & derivados , Niacinamida/metabolismo , Dibenzodioxinas Policloradas/toxicidade , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Timo/efeitos dos fármacos , Timo/embriologia , Timo/metabolismo
20.
Chem Biol Interact ; 331: 109284, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-33035518

RESUMO

Glutathione S-transferases (GSTs) are a key enzyme superfamily involved in the detoxification and cytoprotection of a wide variety of xenobiotics, such as carcinogens, anticancer drugs, environmental toxicants, and endogenously produced free radicals. In the liver, the hGSTA1 isoenzyme is the most abundant and catalyzes the glutathione conjugation of a wide range of electrophiles and has been the principal GST responsible for xenobiotic detoxification. Given the critical role of this enzyme in several cellular processes, particularly cell detoxification, understanding the molecular mechanisms underlying the regulation of hGSTA1 expression is critical. Therefore, the aim of the present study was to investigate whether AHR is involved in the modulation of hGSTA1 gene expression and to characterize the molecular mechanism through which AHR exerts this regulation. Two xenobiotic response elements (XREs) were located at -602 bp and -1030 bp from the transcription start site at the hGSTA1 gene promoter. After treatment of HepG2 cells with beta-naphthoflavone (ß-NF), an AHR agonist, induction of hGSTA1 mRNA was observed. This effect was mediated by the recruitment of AHR to the hGSTA1 gene promoter and its transactivation, as indicated by the ChIP, EMSA and luciferase activity assays. The increase in hGSTA1 transcription regulated by AHR also resulted in enhanced levels of hGSTA1 protein and activity. Taken together, our data suggest that AHR ligands have the potential to modify xenobiotic and endobiotic metabolism mediated by hGSTA1, thereby altering the detoxification of xenobiotics, steroidogenesis and the efficacy of chemotherapeutic agents.


Assuntos
Glutationa Transferase/metabolismo , Receptores de Hidrocarboneto Arílico/metabolismo , Sequência de Bases , Ensaio de Desvio de Mobilidade Eletroforética , Inibidores Enzimáticos/farmacologia , Glutationa Transferase/genética , Células Hep G2 , Humanos , Regiões Promotoras Genéticas , Receptores de Hidrocarboneto Arílico/agonistas , Sítio de Iniciação de Transcrição , Ativação Transcricional/efeitos dos fármacos , beta-Naftoflavona/farmacologia
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