Project description:Toxicogenomic Dissection of the Perfluorooctanoic Acid (PFOA) Transcript Profile in Mouse Liver: Evidence for the Involvement of Nuclear Receptors PPARalpha and CAR We performed a toxicogenomics dissection of the transcript profiles in the mouse liver after exposure to PFOA. We uncovered classes of genes that were regulated independently of PPARalpha. Some of these genes, including those involved in lipid metabolism, may be regulated by PPARbeta/delta or PPARgamma, whereas others, such as those involved in xenobiotic metabolism are likely regulated through CAR. Keywords: toxicogenomic analysis
Project description:Phenobarbital is a well studied xenobiotic compound. In this study, we describe the genomic responses in fruit flies and examine whether animals mutant for DHR96, an ortholog of xenobiotic nuclear receptors PXR and CAR, plays a role in mediating xenobiotic responses in Drosophila. Keywords: dose response in mutant vs. wild type
Project description:β-catenin signaling can be both a physiological and an oncogenic pathway in the liver. It controls compartmentalized gene expression, allowing the liver to ensure its essential metabolic function. It is activated by mutations in 20 to 40% of hepatocellular carcinomas with specific metabolic features. We decipher the molecular determinants of β-catenin-dependent zonal transcription using mice with β-catenin-activated or -inactivated hepatocytes, characterizing in vivo their chromatin occupancy by Tcf4 and β-catenin, their transcriptome and their metabolome. We find that Tcf4 DNA-bindings depend on β-catenin. Tcf4/β-catenin binds Wnt-responsive elements preferentially around β-catenin-induced genes. In contrast, genes repressed by β-catenin bind Tcf4 on Hnf4-responsive elements. β-catenin, Tcf4 and Hnf4α interact, dictating β-catenin transcription which is antagonistic to that elicited by Hnf4α. Finally, we find the drug/bile metabolism pathway to be the one most heavily targeted by β-catenin, partly through xenobiotic nuclear receptors. We conclude that β-catenin patterns the zonal liver together with Tcf4, Hnf4α and xenobiotic nuclear receptors. This network represses lipid metabolism, and exacerbates glutamine, drug and bile metabolism, mirroring hepatocellular carcinomas with β-catenin mutational activation. In vivo liver samples in 4 conditions: Betacat activated (WCE, Tcf4 chipseq, Betacat chipseq, mRNAseq with 2 replicates), Betacat null (WCE, Tcf4 chipseq, mRNAseq with 2 replicates), Betacat control (mRNAseq with 2 replicates), Wild type (mRNAseq with 2 replicates)
Project description:β-catenin signaling can be both a physiological and an oncogenic pathway in the liver. It controls compartmentalized gene expression, allowing the liver to ensure its essential metabolic function. It is activated by mutations in 20 to 40% of hepatocellular carcinomas with specific metabolic features. We decipher the molecular determinants of β-catenin-dependent zonal transcription using mice with β-catenin-activated or -inactivated hepatocytes, characterizing in vivo their chromatin occupancy by Tcf4 and β-catenin, their transcriptome and their metabolome. We find that Tcf4 DNA-bindings depend on β-catenin. Tcf4/β-catenin binds Wnt-responsive elements preferentially around β-catenin-induced genes. In contrast, genes repressed by β-catenin bind Tcf4 on Hnf4-responsive elements. β-catenin, Tcf4 and Hnf4α interact, dictating β-catenin transcription which is antagonistic to that elicited by Hnf4α. Finally, we find the drug/bile metabolism pathway to be the one most heavily targeted by β-catenin, partly through xenobiotic nuclear receptors. We conclude that β-catenin patterns the zonal liver together with Tcf4, Hnf4α and xenobiotic nuclear receptors. This network represses lipid metabolism, and exacerbates glutamine, drug and bile metabolism, mirroring hepatocellular carcinomas with β-catenin mutational activation.
Project description:Toxicogenomic Dissection of the Perfluorooctanoic Acid (PFOA) Transcript Profile in Mouse Liver: Evidence for the Involvement of Nuclear Receptors PPARalpha and CAR; We performed a toxicogenomics dissection of the transcript profiles in the mouse liver after exposure to PFOA. We uncovered classes of genes that were regulated independently of PPARalpha. Some of these genes, including those involved in lipid metabolism, may be regulated by PPARbeta/delta or PPARgamma, whereas others, such as those involved in xenobiotic metabolism are likely regulated through CAR. Experiment Overall Design: 129S1/SvlmJ wild-type and PPARalpha-null mice were exposed to 3 mg/kg/day PFOA or water for 7 days. Total RNA was isolated from liver samples and gene expression analyzed using Affymetrix Mouse 430 2.0 GeneChips. Data from 16 samples, with four mice in each of the 4 treatment groups, were analyzed.
Project description:Phenobarbital is a well studied xenobiotic compound. In this study, we describe the genomic responses in fruit flies and examine whether animals mutant for DHR96, an ortholog of xenobiotic nuclear receptors PXR and CAR, plays a role in mediating xenobiotic responses in Drosophila. Experiment Overall Design: Canton S is a commonly used wild type control strain for xenobiotic studies. Wild type or DHR96 mutant flies were starved overnight and then exposed to either sucrose alone or sucrose supplemented with 0.3% Phenobarbital.
Project description:The v-erbA oncogene belongs to a superfamily of transcription factors called nuclear receptors, which includes the retinoic acid receptors (RARs) responsible for mediating the effects of retinoic acid (RA). Nuclear receptors bind to specific DNA sequences in the promoter region of target genes and v-erbA is known to exert a dominant negative effect on the activity of the RARs. The repressor activity of v-erbA has been linked to the development of hepatocellular carcinoma (HCC) in a mouse model. We have used microarray analysis to identify genes differentially expressed in hepatocytes in culture (AML12 cells) stably transfected with v-erbA and exposed to RA. We have found that v-erbA can affect expression of RA-responsive genes. We have also identified a number of v-erbA-responsive genes that are known to be involved in carcinogenesis and which may play a role in the development of HCC. Experiment Overall Design: AML12 control cells and v-erbA-transfected AML12 cells were exposed to 1 µM RA for 3h or 24h. Using microarray analysis, we compared gene expression in the presence and absence of v-erbA and identified RA-regulated genes differentially expressed in the presence of v-erbA.
Project description:The v-erbA oncogene belongs to a superfamily of transcription factors called nuclear receptors, which includes the retinoic acid receptors (RARs) responsible for mediating the effects of retinoic acid (RA). Nuclear receptors bind to specific DNA sequences in the promoter region of target genes and v-erbA is known to exert a dominant negative effect on the activity of the RARs. The repressor activity of v-erbA has been linked to the development of hepatocellular carcinoma (HCC) in a mouse model. We have used microarray analysis to identify genes differentially expressed in hepatocytes in culture (AML12 cells) stably transfected with v-erbA and exposed to RA. We have found that v-erbA can affect expression of RA-responsive genes. We have also identified a number of v-erbA-responsive genes that are known to be involved in carcinogenesis and which may play a role in the development of HCC.
Project description:Unlike the PPARalpha agonist W14,643, PFOA is capable of inducing effects independently of PPARa. Genes altered in the PPARalpha-null mouse following exposure to PFOA included those associated with fatty acid metabolism, inflammation, xenobiotic metabolism, and cell cycle progression. The specific signaling pathway(s) responsible for these effects is not readily apparent but it is conceivable that other members of the nuclear receptor superfamily such as PPARbeta/delta and CAR may be involved. Keywords: dose response
Project description:Fine particulate matter (PM2.5) pollution remains a major threat to public health. As the physical barrier against inhaled air pollutants, airway epithelium is a primary target for PM2.5 and influenza viruses, two major environmental insults. Recent studies have shown that PM2.5 and influenza viruses may interact to aggravate airway inflammation, an essential event in the pathogenesis of diverse pulmonary diseases. Airway epithelium plays a critical role in lung health and disorders. Thus far, the mechanisms for the interactive effect of PM2.5 and the influenza virus on gene transcription of airway epithelial cells have not been fully uncovered. In this present pilot study, the transcriptome sequencing approach was introduced to identify responsive genes following individual and co-exposure to PM2.5 and influenza A (H3N2) viruses in a human bronchial epithelial cell line (BEAS-2B). Enrichment analysis revealed the function of differentially expressed genes (DEGs). Specifically, the DEGs enriched in the xenobiotic metabolism by the cytochrome P450 pathway were linked to PM2.5 exposure. In contrast, the DEGs enriched in environmental information processing and human diseases, such as viral protein interaction with cytokines and cytokine receptors and epithelial cell signaling in bacterial infection, were significantly related to H3N2 exposure. Meanwhile, this study found that co-exposure to PM2.5 and H3N2 may affect G protein-coupled receptors on the cell surface by modulating Ca2+. Thus, the results from this study provides insights into PM2.5- and influenza virus-induced airway inflammation and potential mechanisms