Humans and ecological species have been found to have detectable body burdens of a number of perfluorinated alkyl acids (PFAA) including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). In mouse and rat liver these compounds elicit transcriptional and phenotypic effects similar to peroxisome proliferator chemicals (PPC) that work through the nuclear receptor peroxisome proliferator activated receptor alpha (PPARalpha). Recent studies indicate that along with PPARalpha other nuclear receptors are required for transcriptional changes in the mouse liver after PFOA exposure including the constitutive activated receptor (CAR) and pregnane X receptor (PXR) that regulate xenobiotic metabolizing enzymes (XME). To determine the potential role of CAR/PXR in mediating effects of PFAAs in rat liver, we performed a meta-analysis of transcript profiles from published studies in which rats were exposed to PFOA or PFOS. We compared the profiles to those produced by exposure to prototypical activators of CAR (Phenobarbital (PB)), PXR (pregnenolone 16 alpha-carbonitrile (PCN)), or PPARalpha (WY-14,643 (WY)). As expected, PFOA and PFOS elicited transcript profile signatures that included many known PPARalpha target genes. Numerous XME genes were also altered by PFOA and PFOS but not WY. These genes exhibited expression changes shared with PB or PCN. Reexamination of the transcript profiles from the livers of chicken or fish exposed to PFAAs indicated that PPARalpha, CAR, and PXR orthologs were not activated. Our results indicate that PFAAs under these experimental conditions activate PPARalpha, CAR, and PXR in rats but not chicken and fish. Lastly, we discuss evidence that human populations with greater CAR expression have lower body burdens of PFAAs.
Keywords: gene expression/microarray
Overall design
We used published and unpublished microarray gene expression profiling data to perform a meta-analysis to reveal the activation of CAR and PXR regulated genes in rat liver exposed to PFAA. This file contains part of data being analyzed.
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