Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Transcription profiling of rat liver samples treated with clofibrate, valproic acid and diethylhexylphthalate

ABSTRACT: The project had 2 goals:; 1) To evaluate the transcriptional response of 3 prototypical toxicants (Clofibrate, VPA, and DEHP) on rat lever. 2) To evaluate the impact pooling samples has on data analysis. Experiment Overall Design: Male SD rats were given a single dose of one of 3 prototypical toxicants or dosed with vehicle. The toxicants used were: Experiment Overall Design: 1000mg/kg Clofibrate (in 0.9% saline) Experiment Overall Design: 2000mg/kg Sodium Valproate (in distilled water) Experiment Overall Design: 20g/kg DEHP (in distilled water) Experiment Overall Design: Animals were sacrificed at 4, 24, 48, or 168hrs post-dosing (only 48 and 168hrs for vehicle-treated animals) Experiment Overall Design: One of the goals of this study was to assess the impact pooling RNA samples has on the array data. For each treatment and vehicle group there are 3-5 individual samples, as well as 1 pooled sample. Experiment Overall Design: 10ug of total RNA were hybridized to Affymetrix RG_U34A arrays according to the manufacturer's protocol. Signal intensities were generated using MAS5, with global scaling set to 1500.

ORGANISM(S): Rattus norvegicus

SUBMITTER: Keith Goldstein

PROVIDER: E-GEOD-2303 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Pooling samples within microarray studies: a comparative analysis of rat liver transcription response to prototypical toxicants.

Jolly Robert A RA Goldstein Keith M KM Wei Tao T Gao Hong H Chen Peining P Huang Shuguang S Colet Jean-Marie JM Ryan Timothy P TP Thomas Craig E CE Estrem Shawn T ST

Physiological genomics 20050524 3

Combining or pooling individual samples when carrying out transcript profiling using microarrays is a fairly common means to reduce both the cost and complexity of data analysis. However, pooling does not allow for statistical comparison of changes between samples and can result in a loss of information. Because a rigorous comparison of the identified expression changes from the two approaches has not been reported, we compared the results for hepatic transcript profiles from pooled vs. individu ...[more]

PMID: 15914576

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Project description:Combining or pooling individual samples when carrying out transcript profiling using microarrays is a fairly common means to reduce both the cost and complexity of data analysis. However, pooling does not allow for statistical comparison of changes between samples and can result in a loss of information. Because a rigorous comparison of the identified expression changes from the two approaches has not been reported, we compared the results for hepatic transcript profiles from pooled vs. individual samples. Hepatic transcript profiles from a single-dose time-course rat study in response to the prototypical toxicants Clofibrate [CAS:637-07-0;CHEBI:3750], Diethylhexyl phthalate DEHP [CAS:117-81-7;CHEBI:17243], and valproic acid VPA [CAS:1069-66-5;CHEBI:9925],were evaluated. Approximately 50% more transcript expression changes were observed in the individual (statistical) analysis compared with the pooled analysis. While the majority of these changes were less than twofold in magnitude (~80%), a substantial number were greater than twofold (~20%). Transcript changes unique to the individual analysis were confirmed by quantitative RT-PCR, while all the changes unique to the pooled analysis did not confirm. The individual analysis identified more hits per biological pathway than the pooled approach. Many of the transcripts identified by the individual analysis were novel findings and may contribute to a better understanding of molecular mechanisms of these compounds. Furthermore, having individual animal data provided the opportunity to correlate changes in transcript expression to phenotypes (i.e., histology) observed in toxicology studies. The two approaches were similar when clustering methods were used despite the large difference in the absolute number of transcripts changed. In summary, pooling reduced resource requirements substantially, but the individual approach enabled statistical analysis that identified more gene expression changes to evaluate mechanisms of toxicity. An individual animal approach becomes more valuable when the overall expression response is subtle and/or when associating expression data to variable phenotypic responses.

Project description:The developing epigenome changes rapidly, potentially making it more sensitive to toxicant exposures. DNA modifications, including methylation and hydroxymethylation, are important parts of the epigenome that may be affected by environmental exposures. However, most studies do not differentiate between these two DNA modifications, possibly masking significant effects. To investigate the relationship between DNA hydroxymethylation and developmental exposure to common contaminants, a collaborative, NIEHS-sponsored consortium, TaRGET II, initiated longitudinal mouse studies of developmental exposure to human-relevant levels of the phthalate plasticizer di(2-ethylhexyl) phthalate (DEHP), and the metal lead (Pb). Exposures to 25 mg DEHP/kg of food (approximately 5 mg DEHP/kg body weight) or 32 ppm Pb-acetate in drinking water were administered to nulliparous adult female mice. Exposure began 2 weeks before breeding, and continued throughout pregnancy and lactation, until offspring were 21 days old. At 5 months, perinatally exposed offspring blood and cortex tissue were collected, for a total of 25 male mice and 17 female mice (n=5-7 per tissue and exposure). DNA was extracted and hydroxymethylation was measured using hydroxymethylated DNA immunoprecipitation sequencing (hMeDIP-seq). Differential peak and pathway analysis was conducted comparing across exposure groups, tissue types, and animal sex, using an FDR cutoff of 0.15. DEHP-exposed females had two genomic regions with lower hydroxymethylation in blood and no differences in cortex hydroxymethylation. For DEHP-exposed males, ten regions in blood (six higher and four lower) and 246 regions (242 higher and four lower) and four pathways in cortex were identified. Pb-exposed females had no statistically significant differences in blood or cortex hydroxymethylation compared to controls. Pb-exposed males, however, had 385 regions (all higher) and six pathways altered in cortex, but no differential hydroxymethylation was identified in blood. Overall, perinatal exposure to human-relevant levels of two common toxicants showed differences in DNA hydroxymethylation specific to sex, exposure type, and tissue, but male cortex was most susceptible to hydroxymethylation differences by exposure. Future assessments should focus on understanding if these findings indicate potential biomarkers of exposure or are related to functional long-term health effects.

Project description:BACKGROUND: Phthalates are manmade industrial additives used mostly as plasticizers. In addition to their deleterious effects on male genital development, population studies have recently documented correlations between phthalates exposure and subtle impacts on reproductive tract development and on the metabolic syndrome in male adults. In mature rodents liver di-(2-ethylhexyl)-phthalate (DEHP) activates the peroxisome proliferators-activated receptor (PPARalpha), a member of the nuclear receptor (NR) superfamily. OBJECTIVES: Using a systems biology approach, we aimed at defining potential mechanisms underlying the impacts of DEHP on adult mouse liver and testis. METHODS: Thus, we performed a parallel analysis of transcript and metabolic profiles in the liver from adult mice exposed to varying DEHP doses. Moreover, we obtained pangenomic mRNA profiles of laser-captured Leydig and Sertoli cells from mature animals exposed to DEHP. RESULTS: Hepatic genes modulated by DEHP are predominantly PPARalpha targets. However, the induction of some prototypic cytochrome P450 genes strongly supports the activation of additional NR pathways. Integration of hepatic transcriptomic and metabonomic profiles further revealed a correlation between the impacts of DEHP on a cluster of genes and metabolites linked to heme synthesis and on a cluster of Rev-erbalpha target genes related to metabolic and circadian clock pathways. Cell-specific effects of DEHP were investigated in the adult testis and a noticeable impact of DEHP was observed on Leydig cells transcriptome. CONCLUSIONS: We report a detailed analysis of DEHP interference with hepatic Constitutive Androstane Receptor (CAR) and Rev-erbalpha pathways and a novel transcriptional impact of DEHP on adult endocrine cells of the testis. Experiment Overall Design: two condition experiment, Sertoli cells-rich areas from DEHP-treated mice vs. Sertoli cells-rich areas from vehicle-treated mice. Biological replicates: 4 DEHP-treated samples and 4 vehicle-treated samples. Dye-swap design. N=4 DEHP-treated vs vehicle-treated x 2 microarrays (dye-swap)=8 microarrays

Project description:BACKGROUND: Phthalates are manmade industrial additives used mostly as plasticizers. In addition to their deleterious effects on male genital development, population studies have recently documented correlations between phthalates exposure and subtle impacts on reproductive tract development and on the metabolic syndrome in male adults. In mature rodents liver di-(2-ethylhexyl)-phthalate (DEHP) activates the peroxisome proliferators-activated receptor (PPARalpha), a member of the nuclear receptor (NR) superfamily. OBJECTIVES: Using a systems biology approach, we aimed at defining potential mechanisms underlying the impacts of DEHP on adult mouse liver and testis. METHODS: Thus, we performed a parallel analysis of transcript and metabolic profiles in the liver from adult mice exposed to varying DEHP doses. Moreover, we obtained pangenomic mRNA profiles of laser-captured Leydig and Sertoli cells from mature animals exposed to DEHP. RESULTS: Hepatic genes modulated by DEHP are predominantly PPARalpha targets. However, the induction of some prototypic cytochrome P450 genes strongly supports the activation of additional NR pathways. Integration of hepatic transcriptomic and metabonomic profiles further revealed a correlation between the impacts of DEHP on a cluster of genes and metabolites linked to heme synthesis and on a cluster of Rev-erbalpha target genes related to metabolic and circadian clock pathways. Cell-specific effects of DEHP were investigated in the adult testis and a noticeable impact of DEHP was observed on Leydig cells transcriptome. CONCLUSIONS: We report a detailed analysis of DEHP interference with hepatic Constitutive Androstane Receptor (CAR) and Rev-erbalpha pathways and a novel transcriptional impact of DEHP on adult endocrine cells of the testis. Experiment Overall Design: two condition experiment, Leydig cells from DEHP-treated mice vs. Leydig cells from vehicle-treated mice. Biological replicates: 2 DEHP-treated samples and 3 vehicle-treated samples. Each treated sample has been hybridized against each vehicle-treated sample in a dye-swap design. N=2 DEHP-treated x 3 vehicle-treated x 2 microarrays=12 microarrays

Dataset Information

Transcription profiling of rat liver samples treated with clofibrate, valproic acid and diethylhexylphthalate

Publications

Pooling samples within microarray studies: a comparative analysis of rat liver transcription response to prototypical toxicants.

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