Please note that we have stopped the regular imports of Gene Expression Omnibus (GEO) data into ArrayExpress. This may not be the latest version of this experiment.
E-GEOD-69521 - Hepatic miRNA profiles and thyroid hormone homeostasis in rats exposed to dietary potassium perfluorooctanesulfonate (PFOS) [miRNA]
Released on 1 August 2015, last updated on 19 August 2015
Perfluorooctanesulfonate (PFOS) has been widely used in a variety of industrial and commercial applications as a surfactant and stain repellent. PFOS causes liver damage (including liver tumors) in experimental animals, primarily via interaction with PPARa and CAR/PXR. We investigated the involvement of microRNAs (miRNAs) in PFOS-induced hepatotoxicity, and mechanisms involved in abnormal TH homeostasis, in the livers of adult male rats exposed in feed to 50 mg PFOS/kg diet for 28 days. PFOS-treated rats exhibited expected histopathological and clinical chemistry changes. Global gene expression changes were consistent with the involvement of PPARα and CAR/PXR in PFOS-induced effects. Thirty-eight miRNAs were significantly altered. Three members of the miR-200 family were the most increased, while miR-122 and miR-21 were the most decreased, in PFOS-treated relative to control rats. Expression of the miR-23b/27b/24 cluster also decreased in PFOS-treated animals. Pathway analysis of miRNAs and associated gene expression changes demonstrated enrichment of transcripts involved in epithelial to mesenchymal transition (EMT), which is a primary process involved in tumor cell motility and cancer metastasis. Liver expression analysis revealed transcripts that may mediate PFOS effects on thyroid hormone (TH) homeostasis including: activation of the CAR/PXR pathway, phase II/III enzymes, and deiodinase. These changes are consistent with low serum TH due to enhanced metabolic clearance of TH. However, most TH hepatic target genes were not altered in a manner consistent with reduced TH signalling; suggesting that PFOS exposure did not induce functional hypothyroidism. Collectively, PFOS-induced miRNA perturbations were strongly associated with EMT suggesting an important role for miRNAs in PFOS-induced hepatotoxicity. The work also provides novel insights into the effects of PFOS on TH homeostasis. Total RNAs from liver samples (4 animals from each group) were labelled using the miRNA Complete Labelling and Hybridization kit (Agilent Technologies). Labelled RNA was hybridized on 8 X 15K Agilent rat miRNA microarray slides. Arrays were scanned using an Agilent G2505B scanner (5 μm resolution). Agilent Feature Extraction (version 10.7.3.1) was used to acquire the fluorescence intensity of each probe. The quality of the microarray data was evaluated using Agilent Feature Extraction quality control metrics. Data were normalized in R using cyclic-lowess (Bolstad et al., 2003). Ratio-intensity plots, boxplots and cluster analyses were used to identify potential outliers. One control sample failed the quality control tests and was eliminated for subsequent analyses. Statistically significantly altered miRNAs were identified using the methods described above for gene expression.
transcription profiling by array
hongyan dong <email@example.com>, Andrew Williams, Carole L Yauk, Genevieve Bondy, Hongyan Dong, Ivan H Curran, Michael G Wade