Ligand-activated and -unactivated AHR in wiltype and mutant hepatoma cells
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE11796 | GEO | 2009/04/17
SECONDARY ACCESSION(S): PRJNA106001
REPOSITORIES: GEO
Similar Datasets
Project description:Starting with our early global expression analyses of TCDD-treated human hepatoma cells {Puga, 2000 4679 /id}, the AHR transcriptional induction profile has been extensively studied, whether activated by TCDD, B[a]P or in the absence of exogenous ligands (reviewed in {Frericks, 2007 5618 /id}). In addition to using prior knowledge to integrate expression profiles into the AHR gene target network, we performed a new set of expression profile analyses of wild type Hepa-1c1c7 and c35 cell lines and compared the responses in naïve cells with responses in TCDD or B[a]P exposed cells for 8 hours. Results of our expression array studies are in close agreement with current knowledge. Experiment Overall Design: Three biological replicates were each performed for wildype naïve cells (DMSO), TCDD activated cells, and B[a]P activated cells, and for c35 (AHR mutant) naïve cells (DMSO), TCDD activated cells, and B[a]P activated cells.
2009-04-25 | E-GEOD-11796 | biostudies-arrayexpress
Project description:Dioxin-like chemicals are well-known for their ability to upregulate expression of numerous genes via the AH receptor (AHR). However, recent transcriptomic analyses in several laboratories indicate that dioxin-like chemicals or AHR genotype itself also can downregulate levels of mRNAs encoded by numerous genes. The mechanism responsible for such downregulation is unknown. We hypothesized that microRNAs (miRNAs), which have emerged as powerful negative regulators of mRNA levels in several systems, might be responsible for mRNA downregulation in dioxin/AHR pathways. We conducted a thorough investigation to address the following questions: (1) does AHR genotype itself affect constitutive expression of microRNAs? (2) does TCDD affect microRNA levels and, if so, is this response dependent on the AHR? (3) does TCDD affect microRNA levels differently in animals that are sensitive to dioxin toxicity versus those that are dioxin-resistant? We used the Exiqon miRNA array platform as well as quantitative RT-PCR to measure miRNA levels in wildtype vs. Ahr-null mice. Treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in vivo caused few changes in miRNA levels in mouse livers and those changes that were statistically significant were of modest magnitude. AHR genotype had little effect on hepatic miRNA levels, either in constitutive expression or in response to TCDD M-bM-^@M-^S only a few miRNAs differed in expression between Ahr-null mice compared to mice with wildtype AHR. It is unlikely that mRNA downregulation by dioxins is mediated by miRNAs, nor are miRNAs likely to play a significant role in dioxin toxicity in adult mouse liver. Manuscript Submitted: Moffat ID, Boutros PC, Celius T, Pohjanvirta R & Okey AB. Micro-RNAs in rodent liver are refractory to dioxin treatment. Toxicological Sciences May, 2007. Keywords: miRNA expression, gene knockout, response to xenobiotics, genetic modification This was a two-factor, two-level design, the factors being genotype Ahr+/+ (WT) or Ahr-/- (KO) and treatment TCDD-treated (T) or vehicle control (C). Each total-RNA sample was separately labeled either with a Hy3- or a Hy5-fluorophore (Exiqon). Hy3- and Hy5-labeled samples were co-hybridized to an array. Dye-reversal was performed to eliminate dye bias. We tested 3 TCDD-treated and 3 control mice in the Ahr-/- groups and 4 TCDD-treated and 4 control mice in the Ahr+/+ groups. Technical replication of 1 TCDD-treated and 1 control mice in the Ahr-/- groups was performed. A loop design was used.
2007-08-14 | E-GEOD-8468 | biostudies-arrayexpress
Project description:The aryl hydrocarbon receptor (AHR) mediates most of the toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). However, TCDD toxicity phenotypes vary widely between species, strains and even between sexes within a strain. While the exact reasons for this variation remain unclear, it is thought to be related to differences in the structure of the AHR. Previous studies comparing the downstream effects of TCDD exposure between animals with different AHR isoforms have been confounded by the genetic differences between these model systems. To address this issue conclusively, we evaluated three transgenic mouse lines, each of which express a different rat AHR isoform (rWT, DEL, and INS) from two strains of rat with highly divergent TCDD-susceptibilities, within identical genetic backgrounds. Here we profile hepatic transcriptomic responses following exposure to TCDD, and use these to identify transcripts associated with toxicity. We have confirmed that the variation in toxicity is inherent to the AHR isoform. Additionally, we note the enhanced activity of the modified transactivation domain of the DEL isoform, relative to the INS isoform, and provide further evidence that the INS isoform is responsible for the high resistance to TCDD observed in H/W rats. We also uncover several candidate genes that were consistently differentially expressed in TCDD-sensitive mice and rats. Adult male transgenic mice were treated by gavage with 0, 125, 250, 500, or 1000 µg/kg TCDD dissolved in corn oil vehicle. Mice were euthanized 4 days following treatment and liver tissue was harvested for analysis. RNA was isolated and the transcriptome for each animal assayed on separate microarrays.
2016-07-03 | E-GEOD-72270 | biostudies-arrayexpress
Project description:2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a persistent environmental contaminant. Previous reports revealed TCDD activating aryl hydrocarbon receptor (AhR) pathway and causing cardiac damage. However, the mechanism of AhR-induced cardiac defect in response to TCDD exposure remains unclear. In this study, we characterized the impacts of TCDD exposure on heart morphology and cardiac function in zebrafish. To investigate the differentially expressed genes under TCDD exposure, we collected the zebrafish larave heart from the control and TCDD treatment groups. We then performed gene expression profiling analysis using data obtained from RNA-seq. Transcriptomic profiling showed that, along with an upregulation of the AhR signaling pathway by TCDD, the expression of pro-ferroptosis genes was upregulated, while genes implicated in glutathione metabolism were downregulated. Consistently, lipid peroxidation, as indicated by malonaldehyde (MDA) production, increased in TCDD-exposed cardiac tissue. Accordingly, inhibiting lipid peroxidation with Liproxstatin-1 reversed the adverse cardiac effects under TCDD treatment. Together, our findings demonstrate that AhR-mediated lipid peroxidation contributes to the cardiac developmental defects of TCDD during zebrafish early development.
2022-10-30 | GSE206948 | GEO
Project description:CD4+ T cells from 8-12 week female mice were isolated from wt and AhR-/- mice 24h after injection of 10µg/kg TCDD or solvent control. Keywords: TCDD, AHR, immunosuppression Each experiment was performed in biological duplicates from 4 pooled animals. Since TCDD treatment showed only marginal impact on the gene expression (~10 transcripts effected in wt mice) wt - ko comparisons were performed on pooled profiles from TCDD and solvent mice.
2008-11-25 | E-GEOD-10084 | biostudies-arrayexpress
Project description:Dioxin-like chemicals are well-known for their ability to upregulate expression of numerous genes via the AH receptor (AHR). However, recent transcriptomic analyses in several laboratories indicate that dioxin-like chemicals or AHR genotype itself also can downregulate levels of mRNAs encoded by numerous genes. The mechanism responsible for such downregulation is unknown. We hypothesized that microRNAs (miRNAs), which have emerged as powerful negative regulators of mRNA levels in several systems, might be responsible for mRNA downregulation in dioxin/AHR pathways. We conducted a thorough investigation to address the following questions: (1) does AHR genotype itself affect constitutive expression of microRNAs? (2) does TCDD affect microRNA levels and, if so, is this response dependent on the AHR? (3) does TCDD affect microRNA levels differently in animals that are sensitive to dioxin toxicity versus those that are dioxin-resistant? We used the Exiqon miRNA array platform as well as quantitative RT-PCR to measure miRNA levels in wildtype vs. Ahr-null mice. Treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in vivo caused few changes in miRNA levels in mouse livers and those changes that were statistically significant were of modest magnitude. AHR genotype had little effect on hepatic miRNA levels, either in constitutive expression or in response to TCDD – only a few miRNAs differed in expression between Ahr-null mice compared to mice with wildtype AHR. It is unlikely that mRNA downregulation by dioxins is mediated by miRNAs, nor are miRNAs likely to play a significant role in dioxin toxicity in adult mouse liver. Manuscript Submitted: Moffat ID, Boutros PC, Celius T, Pohjanvirta R & Okey AB. Micro-RNAs in rodent liver are refractory to dioxin treatment. Toxicological Sciences May, 2007. Keywords: miRNA expression, gene knockout, response to xenobiotics, genetic modification
2007-08-15 | GSE8468 | GEO
Project description:CD4+ T cells from 8-12 week female mice were isolated from wt and AhR-/- mice 24h after injection of 10µg/kg TCDD or solvent control. Keywords: TCDD, AHR, immunosuppression
2008-11-25 | GSE10084 | GEO
Project description:The aryl hydrocarbon receptor (AHR) mediates most of the toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). However, TCDD toxicity phenotypes vary widely between species, strains and even between sexes within a strain. While the exact reasons for this variation remain unclear, it is thought to be related to differences in the structure of the AHR. Previous studies comparing the downstream effects of TCDD exposure between animals with different AHR isoforms have been confounded by the genetic differences between these model systems. To address this issue conclusively, we evaluated three transgenic mouse lines, each of which express a different rat AHR isoform (rWT, DEL, and INS) from two strains of rat with highly divergent TCDD-susceptibilities, within identical genetic backgrounds. Here we profile hepatic transcriptomic responses following exposure to TCDD, and use these to identify transcripts associated with toxicity. We have confirmed that the variation in toxicity is inherent to the AHR isoform. Additionally, we note the enhanced activity of the modified transactivation domain of the DEL isoform, relative to the INS isoform, and provide further evidence that the INS isoform is responsible for the high resistance to TCDD observed in H/W rats. We also uncover several candidate genes that were consistently differentially expressed in TCDD-sensitive mice and rats.
2016-01-01 | GSE72270 | GEO
Project description:Over activation of the aryl hydrocarbon receptor (AhR) by TCDD results ampng other phenotypes in severe thymic atrophy accompanied by immunosuppression. The link between thymic atrophy, skewed thymocyte differntiation and immunosuppression is still not fully resolved. This study investigates the TCDD elicted exprssion changes in the ET, cortical thymus epithelial cell line. Keywords: TCDD, AhR, thymic epithelial cells, thymic involution, thymus atrophy
2008-12-31 | GSE10168 | GEO
Project description:The aryl hydrocarbon receptor (AHR) and AHR nuclear translocator (ARNT) activated complex regulates genes in response to the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). AHR has also emerged as a potential therapeutic target for the treatment of human diseases and different cancers, including breast cancer. To better understand AHR and ARNT signaling in breast cancer cells, we used chromatin immunoprecipitation linked to high throughput sequencing to identify AHR- and ARNT-binding sites across the genome in TCDD treated MCF-7 cells. We identified 2,594 AHR-bound, 1,352 ARNT-bound and 882 high confidence AHR/ARNT co-bound regions. No significant differences in the genomic distribution of AHR and ARNT were observed. Approximately 60% of the co-bound regions contained at least one core AHRE, 5'-GCGTG-3'. AHR/ARNT peak density was the highest within 1 kb of transcription start sites (TSS); however, a number of AHR/ARNT co-bound regions were located as far as 100 kb from TSS. De novo motif discovery identified a symmetrical variation of the AHRE (5'-GTGCGTG-3'), as well as FOXA1 and SP1 binding motifs. Microarray analysis identified 104 TCDD responsive genes where 98 genes were up-regulated by TCDD. Of the 104 regulated genes, 69 (66.3%) were associated with an AHR- or ARNT-bound region within 100 kb of their TSS. Overall our study identified AHR/ARNT co-bound regions across the genome, revealed the importance but not absolute requirement for an AHRE in AHR/ARNT interactions with DNA, and identified a modified AHRE motif, thereby increasing our understanding of AHR/ARNT signaling pathway. Examination of genome-wide AHR and ARNT binding pattern in MCF-7
2012-10-24 | E-GEOD-41820 | biostudies-arrayexpress