Chromatin Immunoprecipitation Analysis of Aryl Hydrocarbon Receptor Binding in a Mouse B-cell Line (CH12.LX) Activated with Lipopolysaccharide and Treated with 2,3,7,8-Tetrachlorodibenzo-p-dioxin
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE23708 | GEO | 2010/09/01
SECONDARY ACCESSION(S): PRJNA130893
REPOSITORIES: GEO
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Project description:The objective of the study was to characterize gene expression cascade involved in the suppression of B-cell activation and differentiation by 2,3,7,8-tetrachlorodibenzo-p-dixoxin (TCDD). The underlying hypothesis was that multiple nodes in the B-cell differentiation network are directly or indirectly regulated by TCDD through its receptor, the AHR. The mouse B-cell line (CH12.LX) was plated at 1X10^5 cells/ml at time 0 and activated with lipopolysaccharide (LPS, Salmonella typhosa). The cells were then treated with either dimethyl sulfoxide (DMSO, 0.01%) or 10 nM 2,3,7,8-tetrachlorodibenzo-p-dixoxin (TCDD). The cells were harvested at 0, 8, 12, 24, 36, and 48 hrs post-treatment. At the 0 hr time point, cells were untreated. A total of 4 experimental replicates per time point per treatment group were included with the cells for each replicate treated and harvested on separate days. Single color Affymetrix Mouse 430 2.0 arrays were used.
2010-10-21 | E-GEOD-21272 | biostudies-arrayexpress
Project description:The aryl hydrocarbon receptor (AHR) agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) alters differentiation of B cells and suppresses antibody production. The objectives of this study was to use a combination of whole genome, microarray-based chromatin immunoprecipitation (ChIP-on-chip) and time course gene expression microarray analysis on the mouse B-cell line CH12.LX following exposure to lipopolysaccharide (LPS) or LPS and TCDD to identify the primary and downstream transcriptional elements of B-cell differentiation that are altered by the AHR. CH12.LX cells (1X10^5 cells/ml, 25ml in P150s) were treated with either 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)(10nM) or vehicle (0.01% DMSO) for 1 hr and cells were fixed with 1% formaldehyde for 15 min and quenched with 0.125 M glycine. Chromatin was isolated by adding lysis buffer followed by disruption with a Dounce homogenizer. Lysates were sonicated and the DNA sheared to an average length of 300-500 bp. Genomic DNA was prepared by treating aliquots of chromatin with RNase, proteinase K and heat for de-crosslinking, followed by ethanol precipitation. Pellets were resuspended and the resulting DNA was quantified on a Nanodrop ND-1000 spectrophotometer. Extrapolation to the original chromatin volume allowed quantitation of the total chromatin yield. An aliquot of chromatin (30 ug) was precleared with protein - agarose beads. Factor-bound DNA sequences were isolated using antibodies against AhR (Biomol, Plymouth Meeting, PA, Catalog #: SA210-0100). After incubation at 4°C overnight, protein-agarose beads were used to isolate the immune complexes. Complexes were washed, eluted from the beads with SDS buffer, and subjected to RNase and proteinase K treatment. Crosslinks were reversed by incubation overnight at 65°C, and ChIP DNA was purified by phenol-chloroform extraction and ethanol precipitation. Following purification ChIP DNA was labeled, fragmented and hybridized to Affymetrix GeneChip Mouse Tiling 2.0 Array Sets, hybridized arrays were then washed and scanned using a GeneChip Fluidics Station 450 and a GeneChip 3000 scanner. The ChIP studies were performed in triplicate (n = 3) with the cells for each replicate treated and harvested on separate days.
2010-08-31 | E-GEOD-23708 | biostudies-arrayexpress
Project description:The objective of the study was to characterize gene expression cascade involved in the suppression of B-cell activation and differentiation by 2,3,7,8-tetrachlorodibenzo-p-dixoxin (TCDD). The underlying hypothesis was that multiple nodes in the B-cell differentiation network are directly or indirectly regulated by TCDD through its receptor, the AHR.
2010-10-21 | GSE21272 | GEO
Project description:The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor in the PAS superfamily of environmental sensors that is linked to several metabolic diseases, including non-alcoholic fatty liver disease (NAFLD). Much remains unknown regarding the impact of genetic variation in AHR-driven disease, as past studies have focused on a small number of inbred strains. Recently, the presence of a wide-range of interindividual variability amongst humans was reported in response to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the prototypical ligand of the AHR. In this study, a panel of 14 diverse mouse strains were exposed to TCDD for 10 days to characterize the AHR-mediated response across genetic backgrounds. In this study, responses to TCDD are heavily-dependent on genetic background. While mice carry one of four Ahr alleles that impact the AHR-mediated responses, we observed significant intra-allelic variability suggesting the presence of novel genetic modifiers of AHR signaling. A regression-based approach was used to scan for genes regulated by the AHR and/or associated with TCDD-induced phenotypes. The approach identified seven genes, 2 of which are novel, that are likely regulated by the AHR based on association with hepatic TCDD burden (p≤0.05). Finally, we identified a gene, Dio1, which was associated with change in percent body fat across the diverse set of strains (p≤0.05). Overall, the results in this study exemplify the power of genetics-based approaches in identifying novel genes that are putatively regulated by the AHR.
2021-05-01 | GSE167328 | GEO
Project description:Alternative splicing is a co-transcriptional mechanism by including or excluding exons in different combinations, thereby expanding the diversity of protein isoforms of a single gene. Abnormalities in this process can result in deleterious effects to human health, and several xenobiotics are known to interfere with splicing regulation through multiple mechanisms. These changes could lead to human diseases such as cancer, neurological disorders, autoimmune diseases, and developmental disorders. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is an environmental contaminant generated as a byproduct of various industrial activities. Exposure to this dioxin has been linked to a wide range of pathologies through the alteration of multiple cellular processes. However, the effects of TCDD exposure on alternative splicing have not yet been studied. Here, we investigate whether exposure to TCDD influenced hepatic alternative splicing in adult male C57BL/6J mice. We identified several genes whose alternative splicing of precursor messenger RNAs was modified following TCDD exposure. In particular, we demonstrated that alternative splicing of Cyp1a1, Ahrr, and Actn1 was significantly altered after TCDD treatment. These findings show that exposure to TCDD has an impact on alternative splicing, presumably through binding to the aryl hydrocarbon receptor, and suggest a new avenue for AhR-mediated pathogenesis.
2019-10-29 | GSE126328 | GEO
Project description:Treatment of mice with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been shown to disrupt many physiological processes including hepatic lipid metabolism, bile acid homeostasis, glucose metabolism, iron and heme homeostasis, and one-carbon metabolism. TCDD disrupts these metabolic pathways mediated by the aryl hydrocarbon receptor (AhR). We have previously shown that the AhR localizes to genomic regions possessing DNA motifs that also contain binding sites for other transcription factors, implicating potential co-operation between the AhR and these other transcription factors in the regulation of target genes. Two possible co-operating transcription factors include HNF4α and COUP-TFII. To investigate interactions between AhR, HNF4α and COUP-TFII hepatic ChIP-seq analysis was performed for HNF4α and COUP-TFII mice treated with TCDD for 2 hours, to supplement pre-existing AhR ChIP-seq data. ChIP-seq analysis revealed genome-wide changes in COUP-TFII and HNF4α binding following treatment with TCDD, with 11,688 and 9,547 genomic regions possessing differential enrichment, respectively. These differentially enriched regions for COUP-TFII and HNF4α fell within the intragenic region of 6,846 and 5,762 genes, respectively. When supplemented with pre-existing AhR ChIP-seq data, AhR, HNF4α and COUP-TFII were found to co-bind to the intragenic region of 6,376 genes.
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Project description:2,3,7,8-TCDD (TCDD) is a reproductive toxicant and endocrine disruptor in nearly all vertebrates, yet the mechanisms by which TCDD induces these reproductive alterations have not been fully characterized. Fish are among the most sensitive vertebrates to the toxic effects of TCDD, and even subtle physiologic changes induced by TCDD can impair reproduction. Previously, we have shown that chronic, sub-lethal exposure to TCDD decreased reproductive capacity, reduced serum estradiol and vitellogenin concentrations, and altered follicular development. Here we investigate the transcriptional changes in zebrafish ovary as they relate to observed attenuated estradiol concentrations and ovarian development. We used quantitative RT-PCR to assess TCDD’s effects on the expression of several candidate genes important in the regulation of follicular development and steroidogenesis. Additionally, global changes in gene expression in the ovary caused by TCDD exposure were identified using Affymetrix Gene Chip Analysis. Our data suggest that TCDD may inhibit follicle maturation via attenuated gonadotropin responsiveness and/or depressed estradiol biosynthesis. Additionally, genes involved in glucose and lipid metabolism, regulation of transcription, and immune function were dysregulated by at least 2-fold suggesting that TCDD alters various integrated networks of signaling pathways. Approximately 89% of dysregulated transcripts contain putative AHR response elements (AHRE) within 5kb upstream of the predicted transcriptional start site suggesting ovarian toxicity is AHRE driven. Furthermore, approximately 49% of dysregulated transcripts contain putative estrogen response elements (ERE) suggesting that dysregulation of estrogen-responsive genes may also contribute to TCDD-induced attenuated follicular development. Patterns in gene expression were correlated with putative EREs and AHREs, and suggest that impacts on the regulation of transcription may play a large role in TCDD’s ovarian toxicity. Taken together, these data illustrate the complexity of TCDD’s ovarian toxicity. Keywords: dose response
2007-09-01 | GSE4859 | GEO
Project description:2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a persistent environmental contaminant that disrupts normal hepatic function. This disruption leads to the development and progression of non-alcoholic fatty liver disease (NAFLD) pathologies, including steatosis, steatohepatitis, and fibrosis. TCDD exerts hepatotoxic effects through activation of the aryl hydrocarbon receptor (AHR) eliciting transcriptional changes. Although diverse liver cell types contribute to TCDD-induced hepatotoxicity, cell-specific transcriptional changes in response to acute TCDD exposure remain unclear. The objective of this project was to elucidate the cell-specific outcomes of AHR activation following acute TCDD exposure. We conducted liver single-nuclei RNA-sequencing from male C57BL/6 mice administered 30 μg/kg of TCDD or sesame oil and sacrificed at 2, 4, 8, 12, 18, 24, or 72 hours post-oral gavage. Leiden clustering and annotation identified 10 major liver cell types, and 2 macrophage and 8 endothelial cell (EC) subtypes. While most cell types maintained their relative abundance, neutrophils exhibited an increase at 72 hours in response to TCDD. Hepatocytes, ECs, and hepatic stellate cells (HSCs) were the only cell types with cell-specific gene expression changes with known AHR binding sites (1,550, 102, and 40, respectively). Functional enrichment analysis in response to TCDD revealed disruptions in the metabolism of steroids, primary bile acids, vitamins, retinols, and glutathione in addition to one-carbon metabolism. EC differential gene expression was associated with PI3-AKT signaling, as well as protein processing and transport pathways. HSCs were enriched in protein processing, ABC transporters, and the dysregulation of tryptophan and linoleic acid metabolism. Altogether, these results suggest that early responses to TCDD trigger cell-specific changes in gene expression in the liver, contributing to hepatotoxicity and the emergence of hepatic pathologies related to NAFLD.
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Project description:2,3,7,8-TCDD (TCDD) is a reproductive toxicant and endocrine disruptor in nearly all vertebrates, yet the mechanisms by which TCDD induces these reproductive alterations have not been fully characterized. Fish are among the most sensitive vertebrates to the toxic effects of TCDD, and even subtle physiologic changes induced by TCDD can impair reproduction. Previously, we have shown that chronic, sub-lethal exposure to TCDD decreased reproductive capacity, reduced serum estradiol and vitellogenin concentrations, and altered follicular development. Here we investigate the transcriptional changes in zebrafish ovary as they relate to observed attenuated estradiol concentrations and ovarian development. We used quantitative RT-PCR to assess TCDDâs effects on the expression of several candidate genes important in the regulation of follicular development and steroidogenesis. Additionally, global changes in gene expression in the ovary caused by TCDD exposure were identified using Affymetrix Gene Chip Analysis. Our data suggest that TCDD may inhibit follicle maturation via attenuated gonadotropin responsiveness and/or depressed estradiol biosynthesis. Additionally, genes involved in glucose and lipid metabolism, regulation of transcription, and immune function were dysregulated by at least 2-fold suggesting that TCDD alters various integrated networks of signaling pathways. Approximately 89% of dysregulated transcripts contain putative AHR response elements (AHRE) within 5kb upstream of the predicted transcriptional start site suggesting ovarian toxicity is AHRE driven. Furthermore, approximately 49% of dysregulated transcripts contain putative estrogen response elements (ERE) suggesting that dysregulation of estrogen-responsive genes may also contribute to TCDD-induced attenuated follicular development. Patterns in gene expression were correlated with putative EREs and AHREs, and suggest that impacts on the regulation of transcription may play a large role in TCDDâs ovarian toxicity. Taken together, these data illustrate the complexity of TCDDâs ovarian toxicity. Experiment Overall Design: A total of eight samples were analyzed including three TCDD doses (10, 40, 100 ppb, dietary exposure) and vehicle control samples. cRNA targets were synthesized from pooled total RNA isolated from five ovaries from different individuals in each treatment group. Each individual contributed equally to a given pool. Two technical replicates were run for each treatment group. Several genes of interest arising from this microarray study were validated by Quantitative RT-PCR with individual ovary samples to assess biological variability.
2009-04-30 | E-GEOD-4859 | biostudies-arrayexpress
Project description:Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces hepatic oxidative stress following activation of the aryl hydrocarbon receptor (AhR). Our recent studies revealed induction of pyruvate kinase muscle isoform 2 (Pkm2) as a novel antioxidant response in normal differentiated hepatocytes. To investigate cooperative regulation between nuclear factor, erythroid derived 2, like 2 (Nrf2) and the AhR, hepatic ChIP-seq analyses were integrated with RNA-seq time course data from mice treated with TCDD for 2 - 168h. ChIP-seq analysis 2h following TCDD treatment revealed genome-wide changes in NRF2 binding. 842 NRF2 enriched regions were in the regulatory region of differentially expressed genes (DEGs) while 579 DEGs showed both NRF2 and AhR enrichment. Sequence analysis showed over-representation of AhR and NRF2 binding motifs in these regions, though presence of motifs were largely independent. NRF2 was negligibly enriched within the Pkm gene loci in a closed chromatin region despite its role in antioxidant defenses. Furthermore, TCDD induced Pkm2 in primary hepatocytes from wild-type and Nrf2 null mice, indicating NRF2 is not required. Although NRF2 and AhR cooperate in the regulation of gene expression associated with antioxidant responses, the induction of Pkm2 by TCDD is not dependent on ROS-mediated activation of NRF2.
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