Exposure to perfluorooctane sulfonate or fenofibrate causes PPAR-α dependent transcriptional responses in chicken embryo hepatocytes

Abstract

Perfluorooctane sulfonate (PFOS) is a globally distributed environmental contaminant that is detected in the serum and liver of numerous mammalian and avian species. PFOS acts as a peroxisome proliferator in rodents, which occurs subsequent to activation of the nuclear receptor peroxisome proliferator activated receptor-alpha (PPAR-α). Activated PPAR-α up-regulates PPAR-α target genes, most of which are involved in lipid metabolism. Although several studies have investigated the effects of PFOS exposure on mammalian gene expression, there are few studies in avian species. To determine if PFOS is capable of activating avian PPAR-α, we exposed chicken embryo primary hepatocyte cultures ( N = 3 independent cell cultures) to PFOS or fenofibrate, a mammalian PPAR-α agonist, and examined the expression of PPAR-α and PPAR-α target genes using quantitative real-time PCR. The target genes examined were peroxisomal acyl-CoA oxidase (ACOX), liver fatty acid binding protein (L-FABP), enoyl-Coenzyme A, hydratase/3-hydroxyacyl Coenzyme A dehydrogenase bifunctional enzyme (BIEN), peroxisomal 3-ketoacyl thiolase (PKT), and malic enzyme (ME). All five target genes were induced in response to PFOS exposure and all of the target genes, except L-FABP, were induced in response to fenofibrate. PPAR-α mRNA expression was not altered by PFOS or fenofibrate. This study provides the first evidence that PFOS can induce PPAR-α-dependent transcriptional responses in an avian species and provides the first characterization of fenofibrate induced transcriptional responses in chicken embryo hepatocyte cultures.