Transcription profiling of human wild type and mutant hepatoma cells botg ligand-activated and -unactivated AHR
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ABSTRACT:
ORGANISM(S): Mus musculus
SUBMITTER: Maureen Sartor
PROVIDER: E-GEOD-11796 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:The human and mouse aryl hydrocarbon receptor (hAHR and mAHRb) share limited (58%) transactivation domain sequence identity. Compared to the mAHRb allele, the hAHR displays 10-fold lower relative affinity for prototypical ligands such as 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD). However, in previous studies we have demonstrated that the hAHR can display a higher relative ligand binding affinity than the mAHRb for specific AHR ligands such as indirubin. Each receptor has also been shown to differentially recruit LXXLL co-activator-motif proteins and to utilize different TAD subdomains in gene transactivation. Using hepatocytes isolated from C57BL6/J mice (Ahrb/b) and AHRTtr transgenic mice which express hAHR protein specifically in hepatocytes, we investigated whether the hAHR and mAHRb differentially regulate genes. Microarray and quantitative-PCR analysis of Ahrb/b and AHRTtr primary-mouse hepatocytes treated with 10 nM TCDD revealed that a number of established AHR target genes such as Cyp1a1 and Cyp1b1 are significantly induced by both receptors. Remarkably, of the 1752 genes induced by mAHRb and 1186 genes induced by hAHR, only 265 genes (<10%) were significantly activated by both receptors in response to TCDD. Conversely of the 1100 and 779 genes significantly repressed in mAHRb and hAHR hepatocytes respectively, only 462 (<25%) genes were significantly repressed by both receptors in response to TCDD treatment. Genes identified as differentially expressed are known to be involved in a number of biological pathways, including cell proliferation and inflammatory response which suggests that compared to the mAHRb, the hAHR may play contrasting roles in TCDD-induced toxicity and endogenous AHR-mediated gene regulation. Experiment Overall Design: Isolated mouse hepatocytes from wild type and treated with 10nM TCDD for 6h were analyzed. 1 array per mouse (3 mice per treatment group) was used.GeneChip® Operating Software (Affymetrix) was utilized to preprocess CAB/CEL files generated from the 12 scanned microarrays which represented hepatocytes isolated from one mouse each. Data quality was initially assessed by checking the array image, B2 oligo performance, average background to noise ratios, poly-A controls, hybridization controls and the 3' to 5' probe-set ratios for control genes (e.g. Ã-actin or GAPDH). Microarray data was normalized using Probe Logarithmic Intensity Error Approximation PLIER-MM algorithm (Affymetrix Expression Console⢠Software 1.1). Normalized microarray data outputs from TCDD and control treated Ahrb/band AHRTtr hepatocytes were compared for differential expression using Significance Analysis of Microarrays (SAM, version 2.23A (Pan 2002; Tusher et al. 2001)) with 100 permutations, KNN-10.
2009-09-13 | E-GEOD-17925 | biostudies-arrayexpress
Project description:The aryl hydrocarbon receptor (AHR) is a ligand activated transcription factor that mediates the toxic effects of the environmental contaminant, dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin; TCDD). Dioxin causes a diverse range of toxic responses, including hepatic damage and lethal wasting syndrome; however, the mechanisms of dioxin-induced toxicity are still unknown. Here we show that the loss of TCDD-inducible poly(ADP-ribose) polymerase (TIPARP; ARTD14), an ADP-ribosyltransferase and AHR repressor, increases sensitivity to dioxin-induced toxicity and lethality. Tiparp-/- mice treated with a single injection of 100 mg/kg dioxin display an accelerated lethal wasting syndrome with no Tiparp-/- mice surviving beyond day 5; all Tiparp+/+ mice survived up to 30 days post treatment. Tiparp-/- mice displayed dramatic increases in liver steatosis and hepatotoxicity. At the molecular level, TIPARP selectively ADP-ribosylates AHR, but not AHR nuclear translocator (ARNT) and the Tiparp-dependent repression of AHR is reversed by the ADP-ribosylase and macrodomain containing protein MacroD1, but not MacroD2. These results describe previously unidentified roles for Tiparp, MacroD1, and ADP-ribosylation in AHR signaling, dioxin toxicity and lethality. 12 samples were analyzed. There were 4 treatment groups and each treatment group was done in triplicate. Gene expression changes were determine in hepatic RNA isolated from (1) corn oil treated C57BL/6;129Sv mice; (2) 30 ug/kg/bw 2,3,7,8-Tetrachlorodibenzo-p-dioxin C57BL/6;129Sv mice; (3) corn oil treated C57BL/6;129Sv Tiparp-/- mice; and (4) 30 ug/kg/bw 2,3,7,8-Tetrachlorodibenzo-p-dioxin C57BL/6;129Sv Tiparp-/- mice
2015-05-14 | E-GEOD-61534 | biostudies-arrayexpress
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 ET cells were grown to 80-90% confluence and treated with 5nM TCDD or solvent control (1,4-Dioxane, 0,05%V). 2h,4h and 6h after treatment, RNA was isolated using TRIzol and gene expression measured. All experiments wer done in biological duplicates.
2008-12-30 | E-GEOD-10168 | biostudies-arrayexpress
Project description:Oxidative stress is an important mechanism of chemical toxicity, contributing to teratogenesis as well as to cardiovascular and neurodegenerative diseases. Developing animals may be especially sensitive to chemicals causing oxidative stress. To assess the response to chemicals at different stages of development, zebrafish (Danio rerio) embryos at 1, 2, 3, 4, 5, and 6 days post-fertilization (dpf) were exposed to 0.1% dimethyl sulfoxide (DMSO), 2 nM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), or 10 uM tert-butylhydroquinone (tBHQ) for 6 hr. Transcript abundance was assessed by real-time qRT-PCR and microarray (Agilent 22k). By microarray, 1477 probes were significantly different among the DMSO-, tBHQ-, and TCDD-treated embryos at 4 dpf. Of these, 220 were 2-fold or greater up-regulated and 108 were 2-fold or greater down-regulated by tBHQ. For TCDD, 17 probes were 2-fold or greater up-regulated and 6 were 2-fold or greater down-regulated. Genes induced by tBHQ, included genes involved in glutathione synthesis and utilization, signal transduction, and DNA damage / stress response. Keywords: Danio rerio, TCDD, tBHQ, oxidative stress, gene expression Separate groups of 30 embryos generated from TL adults were placed in 15 ml egg water in a 10-cm glass petri and at 1, 2, 3, 4, 5, and 6-dpf were exposed for 6 hr to 0.1% dimethyl sulfoxide (DMSO), 2 nM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), or 10 uM tert-butylhydroquinone (tBHQ) (4 replicates per compound per time point). Embyros were frozen immediately after the 6 hr exposure and RNA isolated for microarray analysis. A Universal RNA Reference Sample was created by mixing equal amounts of total RNA from 2 replicates each from all toxicants (TCDD, tBHQ, DMSO) and timepoints (1, 2, 3, 4, 5, 6-dpf). Based on qRT-PCR results, the 4 dpf timepoint was selected for microarray analysis, in which the RNA samples (4 replicates per compound) were Cy3 labeled and co-hybridized with Cy5 labeled Universal RNA Reference Sample to generate data for analysis of variance.
2010-04-03 | E-GEOD-10157 | biostudies-arrayexpress
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
Project description:Five genome-wide microarrays were used to indentify gene expression in exposure to Tributyltin, Dichlorodiphenyltrichloroethane and 2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin. The three environmental chemicals are persistent in environment and cause continuous toxical effects on human and aquatic life. Tetrahymena thermophila has the potential as a toxical model. The genome-wide microarray in Tetrahymena thermophila exposed to these toxicants was analyzed. First, genes differentially expressed under the treatment of each toxicant were identified and then their functions were categorized using GO enrichment analysis. The results may suggest that Tetrahymena thermophila is able to reflect different mechanism of different toxic-type toxicants which are similar to those in multicellular organisms. Regarding the complexity of TCDD effects, context likelihood of relatedness method (CLR) was applied to construct a TCDD-relevant network. General functions of the network are related to the epigenetic mechanism of TCDD. Based on the network analysis, a model of TCDD effect on T. thermophila was infered. Thus, Tetrahymena has the potential to be a good unicellular eukaryotic model for toxic mechanism research at genome level. Tetrahymena thermophila CU428 cells were cultured using 1XSPP, 30 degree, 100 rpm shaking, until 300,000 cells/ml. Cells at 300,000 cells/ml was incubated in SPP medium were treated. Two microarrays were used 4.02μl DMSO per ml SPP as the solvent and control; One microarray for 5 ppb TBT treatment 24 hours; One microarray for 1 ppb TCDD treatment 24 hours; One microarray for 4ppm DDT treatment for 24 hours.
2011-06-30 | E-GEOD-26515 | biostudies-arrayexpress
Project description:To simplify chemical risk assessment, the adverse outcome pathway (AOP) method has arisen as a framework to predict the impact of chemical exposure on human and environmental health. The development of this predictive tool requires knowledge of the molecular interaction between chemicals and protein targets. Here, we demonstrate that the identification and selection of a target candidate to develop adverse outcome pathways can be obtained by applying high-throughput identification of chemical targets by proteome integral solubility alteration (PISA) assay, followed by selecting the priority target candidate by an analytical hierarchy process. From 8 identified protein targets for TCDD from a soluble proteome extracted from hepatocytes, we selected the priority target for developing AOPs. Our combined methodologies provide identification of a molecular initiating event, essential knowledge to link molecular interaction to impact on health. The identification of chemical targets following a systematic analysis of chemical protein interaction by proteomics increases the high-throughput and reduces the traditional bias. The target selection eliminates conflicting criteria by applying a multiple-criteria decision-making analysis.
2023-03-11 | PXD033056 | Pride
Project description:Major toxicities of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) result from dysregulation of gene expression mediated by the aryl hydrocarbon receptor (AHR). Dioxin-like chemicals alter expression of numerous genes in liver but the specific genes whose dysregulation leads to toxicities such as wasting, hepatotoxicity and lethality have not been identified. We searched for genes that are most likely to be key to dioxin toxicity by using gene expression arrays to contrast hepatic gene expression after TCDD treatment in dioxin-sensitive rats (that carry wildtype AHR) with gene expression in H/W(Kuopio) rats which are highly resistant to dioxin toxicity due to a major deletion in the AHR's transactivation domain (TAD). The total number of TCDD-responsive genes was smaller in rats with the AHRH/W genotype than in rats with wildtype AHR. However, genes in the classic AH gene battery such as CYP1A1, CYP1A2 and CYP1B1 remained fully responsive to TCDD in AHRH/W rats; thus the TAD deletion selectively interferes with expression of a subset of hepatic genes rather than abolishing global AHR-mediated responses. Genes in the following functional categories differ in response to TCDD between dioxin-sensitive rats and dioxin-resistant rats: fatty acid oxidation, metabolism (xenobiotic, alcohol, amino acid, and fatty acid), phosphate transport, regulation of steroid biosynthesis, nitrogen compound catabolism, and generation of precursor metabolites and energy. Many of these differentially-responsive genes are integral parts of pathways such as: protein degradation and synthesis, fatty acid metabolism and synthesis, cytokinesis, cell growth, and apoptosis which may be part of mechanisms which lead to TCDD-induced wasting, hepatotoxicity, tumors, and death. These differentially-responsive genes are worthy candidates for further mechanistic studies to test their role in mediating or protecting from major dioxin toxicities. Experiment Overall Design: Four strains of rats were either treated with 100 ug/kg TCDD or cornoil vehicle and profiled at 19 hours, each with four replicates. Two strains were also analyzed at 3 hours, each with four replicates.
2009-12-02 | E-GEOD-10083 | 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 well-defined battery of in vitro systems applied within chemical cancer risk assessment is often characterised by a high false-positive rate, thus repeatedly failing to correctly predict the in vivo genotoxic and carcinogenic properties of test compounds. Toxicogenomics, i.e. mRNA-profiling, has been proven successful in improving the prediction of genotoxicity in vivo and the understanding of underlying mechanisms. Recently, microRNAs have been discovered as post-transcriptional regulators of mRNAs. It is thus hypothesised that using microRNA response-patterns may further improve current prediction methods. This study aimed at predicting genotoxicity and non-genotoxic carcinogenicity in vivo, by comparing microRNA- and mRNA-based profiles, using a frequently applied in vitro liver model and exposing this to a range of well-chosen prototypical carcinogens. Primary mouse hepatocytes (PMH) were treated for 24 and 48h with 21 chemical compounds [genotoxins (GTX) vs. non-genotoxins (NGTX) and non-genotoxic carcinogens (NGTX-C) versus non-carcinogens (NC)]. MicroRNA and mRNA expression changes were analysed by means of Exiqon and Affymetrix microarray-platforms, respectively. Classification was performed by using Prediction Analysis for Microarrays (PAM). Compounds were randomly assigned to training and validation sets (repeated 10 times). Before prediction analysis, pre-selection of microRNAs and mRNAs was performed by using a leave-one-out t-test. No microRNAs could be identified that accurately predicted genotoxicity or non-genotoxic carcinogenicity in vivo. However, mRNAs could be detected which appeared reliable in predicting genotoxicity in vivo after 24h (7 genes) and 48h (2 genes) of exposure (accuracy: 90% and 93%, sensitivity: 65% and 75%, specificity: 100% and 100%). Tributylinoxide and para-Cresidine were misclassified. Also, mRNAs were identified capable of classifying NGTX-C after 24h (5 genes) as well as after 48h (3 genes) of treatment (accuracy: 78% and 88%, sensitivity: 83% and 83%, specificity: 75% and 93%). Wy-14,643, phenobarbital and ampicillin trihydrate were misclassified. We conclude that genotoxicity and non-genotoxic carcinogenicity probably cannot be accurately predicted based on microRNA profiles. Overall, transcript-based prediction analyses appeared to clearly outperform microRNA-based analyses. The study investigated differential gene expression in primary mouse hepatocyte mRNA following 24 and 48 hours of exposure to di(2-ethylhexyl)phthalate(DEHP), 4-Acetylaminofluorene(4AAF), Curcumin(Cur), Phenobarbital(PhB), Reserpine(Res), 7,12-Dimethylbenzanthracene (DMBA), Resorcinol(Resorcinol), Para-cresidine(pCres), Phenacetin(Phen), Diclofenac(diclo), Wy 14643(Wy), Tributyltinoxide(TBTO), Benzo[a]pyrene(BaP), 8-Hydroxyquinoline [AKA 8-quinolinol](8HQ), 17-b-estradiol(E2), ampicillin(AmpC), cisplatin(CisPl), Aflatoxin B1(AFB1), Cyclosporin A(CsA), 2,3,7,8-Tetrachlorodibenzo-p-dioxin(TCDD), Quercetin(Que) or their responsive solvent (dimethylsulfoxide(DMSO), Ethanol(ETOH), phosphate buffered saline(PBS)). Three biological replicates per compound/solvent. In total 184 arrays.
2016-06-28 | E-GEOD-72081 | biostudies-arrayexpress