The Aryl Hydrocarbon Receptor Regulates Tissue-Specific Dioxin-Dependent and Dioxin-Independent Gene Batteries
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE15859 | GEO | 2009/09/18
SECONDARY ACCESSION(S): PRJNA116959
REPOSITORIES: GEO
Similar Datasets
Project description:This SuperSeries is composed of the following subset Series: GSE15857: The Aryl Hydrocarbon Receptor Regulates Tissue-Specific Dioxin-Dependent and Dioxin-Independent Gene Batteries: Kidney GSE15858: The Aryl Hydrocarbon Receptor Regulates Tissue-Specific Dioxin-Dependent and Dioxin-Independent Gene Batteries: Liver Refer to individual Series
2010-05-05 | E-GEOD-15859 | biostudies-arrayexpress
Project description:The aryl hydrocarbon receptor (AHR) is a widely-expressed ligand-dependent transcription-factor that mediates cellular responses to dioxins and other planar aromatic hydrocarbons. Indeed, AHR-null mice are refractory to the physiological effects of dioxin-exposure. Although some mechanistic aspects of AHR activity are well understood, the tissue-specificity of AHR effects remains unclear, both during development and following administration of exogenous ligands. Previously we employed studied the transcriptional responses of wild-type and AHR-null C57BL/6J mice to dioxin-exposure. We found that essentially all hepatic effects of dioxin were mediated by the AHR, and that large numbers of genes were affected by dioxin exposure. Surprisingly, we also identified a large effect of AHR genotype, even in the absence of dioxin-exposure. To help assess the tissue-specificity of AHR activity we replicated that prior study in the kidney from the same animals previously studied, and extensively compared the hepatic and renal transcriptional profiles. We find that dioxin-exposure causes essentially no transcriptional effects in the absence of a functional AHR in either liver or kidney. Surprisingly, aside from a number of well-established AHR target genes, dioxin-exposure has few effects in animals harbouring a wild-type AHR. By contrast, AHR genotype profoundly remodels the renal transcriptome, and is associated with perturbation of specific functional pathways and with specific DNA motifs. Our results demonstrate the importance of inter-tissue comparisons and highlight the basal role of AHR activity in renal and hepatic development or normal physiology. Two-Factor, Two-Level. AHRnull and wildtype mice were treated with dioxin (TCDD) or corn oil vehicle. 3 replicates per treatment for AHRnull mice, 6 replicates of dioxin treatment for wildtype mice, and 5 replicates of corn oil treatment for wildtype mice.
2009-09-21 | E-GEOD-15858 | biostudies-arrayexpress
Project description:The aryl hydrocarbon receptor (AHR) is a widely-expressed ligand-dependent transcription-factor that mediates cellular responses to dioxins and other planar aromatic hydrocarbons. Indeed, AHR-null mice are refractory to the physiological effects of dioxin-exposure. Although some mechanistic aspects of AHR activity are well understood, the tissue-specificity of AHR effects remains unclear, both during development and following administration of exogenous ligands. Previously we employed studied the transcriptional responses of wild-type and AHR-null C57BL/6J mice to dioxin-exposure. We found that essentially all hepatic effects of dioxin were mediated by the AHR, and that large numbers of genes were affected by dioxin exposure. Surprisingly, we also identified a large effect of AHR genotype, even in the absence of dioxin-exposure. To help assess the tissue-specificity of AHR activity we replicated that prior study in the kidney from the same animals previously studied, and extensively compared the hepatic and renal transcriptional profiles. We find that dioxin-exposure causes essentially no transcriptional effects in the absence of a functional AHR in either liver or kidney. Surprisingly, aside from a number of well-established AHR target genes, dioxin-exposure has few effects in animals harbouring a wild-type AHR. By contrast, AHR genotype profoundly remodels the renal transcriptome, and is associated with perturbation of specific functional pathways and with specific DNA motifs. Our results demonstrate the importance of inter-tissue comparisons and highlight the basal role of AHR activity in renal and hepatic development or normal physiology. Two-Factor, Two-Level. AHRnull and wildtype mice were treated with dioxin (TCDD) or corn oil vehicle. 3 replicates per treatment for AHRnull mice, and 6 replicates per treatment for wildtype mice.
2009-09-21 | E-GEOD-15857 | biostudies-arrayexpress
Project description:The aryl hydrocarbon receptor (AHR) is a widely-expressed ligand-dependent transcription-factor that mediates cellular responses to dioxins and other planar aromatic hydrocarbons. Indeed, AHR-null mice are refractory to the physiological effects of dioxin-exposure. Although some mechanistic aspects of AHR activity are well understood, the tissue-specificity of AHR effects remains unclear, both during development and following administration of exogenous ligands. Previously we employed studied the transcriptional responses of wild-type and AHR-null C57BL/6J mice to dioxin-exposure. We found that essentially all hepatic effects of dioxin were mediated by the AHR, and that large numbers of genes were affected by dioxin exposure. Surprisingly, we also identified a large effect of AHR genotype, even in the absence of dioxin-exposure. To help assess the tissue-specificity of AHR activity we replicated that prior study in the kidney from the same animals previously studied, and extensively compared the hepatic and renal transcriptional profiles. We find that dioxin-exposure causes essentially no transcriptional effects in the absence of a functional AHR in either liver or kidney. Surprisingly, aside from a number of well-established AHR target genes, dioxin-exposure has few effects in animals harbouring a wild-type AHR. By contrast, AHR genotype profoundly remodels the renal transcriptome, and is associated with perturbation of specific functional pathways and with specific DNA motifs. Our results demonstrate the importance of inter-tissue comparisons and highlight the basal role of AHR activity in renal and hepatic development or normal physiology.
2009-09-21 | GSE15858 | GEO
Project description:The aryl hydrocarbon receptor (AHR) is a widely-expressed ligand-dependent transcription-factor that mediates cellular responses to dioxins and other planar aromatic hydrocarbons. Indeed, AHR-null mice are refractory to the physiological effects of dioxin-exposure. Although some mechanistic aspects of AHR activity are well understood, the tissue-specificity of AHR effects remains unclear, both during development and following administration of exogenous ligands. Previously we employed studied the transcriptional responses of wild-type and AHR-null C57BL/6J mice to dioxin-exposure. We found that essentially all hepatic effects of dioxin were mediated by the AHR, and that large numbers of genes were affected by dioxin exposure. Surprisingly, we also identified a large effect of AHR genotype, even in the absence of dioxin-exposure. To help assess the tissue-specificity of AHR activity we replicated that prior study in the kidney from the same animals previously studied, and extensively compared the hepatic and renal transcriptional profiles. We find that dioxin-exposure causes essentially no transcriptional effects in the absence of a functional AHR in either liver or kidney. Surprisingly, aside from a number of well-established AHR target genes, dioxin-exposure has few effects in animals harbouring a wild-type AHR. By contrast, AHR genotype profoundly remodels the renal transcriptome, and is associated with perturbation of specific functional pathways and with specific DNA motifs. Our results demonstrate the importance of inter-tissue comparisons and highlight the basal role of AHR activity in renal and hepatic development or normal physiology.
2009-09-21 | GSE15857 | GEO
Project description:Conventional biochemical and molecular techniques identified previously several genes whose expression is regulated by the aryl hydrocarbon receptor (AHR). We sought to map the complete spectrum of AHR-dependent genes in male adult liver using expression arrays to contrast mRNA profiles in Ahr-null mice (Ahr–/–) with those in mice with wild-type AHR (Ahr+/+). Transcript profiles were determined both in untreated mice and in mice treated 19 h earlier with 1000 µg/kg 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Expression of 456 ProbeSets was significantly altered by TCDD in an AHR-dependent manner, including members of the classic AHRE-I gene battery, such as Cyp1a1, Cyp1a2, Cyp1b1, and Nqo1. In the absence of exogenous ligand, AHR status alone affected expression of 392 ProbeSets, suggesting that the AHR has multiple functions in normal physiology. In Ahr–/– mice, only 32 ProbeSets exhibited responses to TCDD, indicating that the AHR is required for virtually all transcriptional responses to dioxin exposure in liver. The flavin-containing monooxygenases, Fmo2 and Fmo3, considered previously to be uninducible, were highly induced by TCDD in an AHR-dependent manner. The estrogen receptor alpha as well as two estrogen-receptor-related genes (alpha and gamma) exhibit AHR-dependent expression, thereby extending cross-talk opportunities between the intensively studied AHR and estrogen receptor pathways. p53 binding sites are over-represented in genes down-regulated by TCDD, suggesting that TCDD inhibits p53 transcriptional activity. Overall, our study identifies a wide range of genes that depend on the AHR, either for constitutive expression or for response to TCDD. Keywords: treatment-control and mutant-wildtype
2008-11-01 | GSE10082 | GEO
Project description:The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor. Activation of AhR mediates the expression of target genes (e.g., CYP1A1) by binding to dioxin response element (DRE) sequences in their promoter region. To understand the multiple mechanisms of AhR-mediated gene regulation, a microarray analysis on liver isolated from ligand-treated transgenic mice expressing a wild-type (WT) Ahr or a DRE-binding mutant Ahr (A78D) on an ahr-null background was performed. Results revealed that AhR DRE binding is not required for the suppression of genes involved in cholesterol synthesis. Quantitative reverse-transcription polymerase chain reaction performed on both mouse liver and primary human hepatocyte RNA demonstrated a coordinated repression of genes involved in cholesterol biosynthesis, namely, HMGCR, FDFT1, SQLE, and LSS after receptor activation. An additional transgenic mouse line was established expressing a liver-specific Ahr-A78D on a Cre(Alb)/Ahr(flox/flox) background. These mice displayed a similar repression of cholesterol biosynthetic genes, compared to Ahr(flox/flox) mice, further indicating that the observed modulation is AhR specific and occurs in a DRE-independent manner. Elevated hepatic transcriptional levels of the genes of interest were noted in congenic C57BL/6J-Ah(d) allele mice, when compared to the WT C57BL/6J mice, which carry the Ah(b) allele. Down-regulation of AhR nuclear translocator levels using short interfering RNA in a human cell line revealed no effect on the expression of cholesterol biosynthetic genes. Finally, cholesterol secretion was shown to be significantly decreased in human cells after AhR activation.These data firmly establish an endogenous role for AhR as a regulator of the cholesterol biosynthesis pathway independent of its DRE-binding ability, and suggest that AhR may be a previously unrecognized therapeutic target.
| S-EPMC3340481 | biostudies-literature
Project description: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.
| S-EPMC7737989 | biostudies-literature
Project description:The Aryl hydrocarbon receptor (Ahr) is the nuclear receptor mediating the toxicity of dioxins--widespread and persistent pollutants whose toxic effects include tumor promotion, teratogenesis, wasting syndrome and chloracne. Elimination of Ahr in mice eliminates dioxin toxicity but also produces adverse effects, some seemingly unrelated to dioxin. Thus the relationship between the toxic and dioxin-independent functions of Ahr is not clear, which hampers understanding and treatment of dioxin toxicity. Here we develop a Drosophila model to show that dioxin actually increases the in vivo dioxin-independent activity of Ahr. This hyperactivation resembles the effects caused by an increase in the amount of its dimerisation partner Ahr nuclear translocator (Arnt) and entails an increased transcriptional potency of Ahr, in addition to the previously described effect on nuclear translocation. Thus the two apparently different functions of Ahr, dioxin-mediated and dioxin-independent, are in fact two different levels (hyperactivated and basal, respectively) of a single function.
| S-EPMC2975661 | biostudies-literature
Project description:Cytochrome P4502E1 (CYP2E1) is involved in the biotransformation of several low molecular weight chemicals and plays an important role in the metabolic activation of carcinogens and hepatotoxins such as CCl(4). Induction of CYP2E1 is exerted mainly at posttranscriptional levels through mRNA and protein stabilization, and there is little evidence of xenobiotic induction at the transcriptional level. Previously, we reported microarray analysis data suggesting a decrease in Cyp2e1 gene expression on Ahr-null livers when compared to wild-type mouse livers. The goal of the present study was to determine whether 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) increased mouse CYP2E1 levels in an AhR-dependent manner and the impact on CCl(4)-induced hepatotoxicity. TCDD treatment induced CYP2E1 mRNA and protein levels in mouse liver, and this effect was aryl hydrocarbon receptor (AhR)-dependent. Moreover, TCDD pre-treatment increased the CCl(4)-induced alanine aminotransferase (ALT) activity, the extent of CCl(4)-induced necrosis, and the number of sinusoidal cells in wild-type animals, while this potentiating effect was not observed in Ahr-null mice. In conclusion, this study revealed that TCDD, probably in an AhR-dependent manner, exacerbated CCl(4)-induced hepatotoxicity through induction of CYP2E1.
| S-EPMC6319626 | biostudies-literature