Activation of sterol regulatory element-binding proteins in mice exposed to perfluorooctanoic acid for 28 days

摘要

Perfluoroalkyl acids are widely used in numerous industrial and commercial applications due to their unique physical and chemical characteristics. Although perfluorooctanoic acid (PFOA) is associated with hepatomegaly through peroxisome proliferator-activated receptor alpha (PPAR alpha) activation, liver fat accumulation and changes in gene expression related to fatty acid metabolism could still be found in PPAR alpha-null mice exposed to PFOA. To explore the potential effects of PFOA on sterol regulatory element-binding proteins (SREBPs) activity, male mice were dosed with either Milli-Q water or PFOA at doses of 0.08, 0.31, 1.25, 5, and 20 mg/kg/day by gavage for 28 days. Liver total cholesterol concentrations and PFOA contents showed a dose-dependent decrease and increase, respectively. Transcriptional activity of PPAR alpha and SREBPs was significantly enhanced in livers. Protein expression analyzed by Western blotting showed that PFOA exposure stimulated SREBP maturation. Furthermore, proteins blocked SREBP precursor transport, insulin-induced gene 1 (INSIG1) and INSIG2 proteins, as well as a protein-mediated nuclear SREBP proteolysis, F-box and WD-40 domain protein 7, decreased in mouse liver exposed to PFOA. The expression levels of the miR-183-96-182 cluster, which is possibly involved in a regulatory loop intermediated by SREBPs maturation, were also increased in the mouse liver after PFOA exposure. We also observed that PFOA induced lipid content and PPAR alpha in Hepa 1-6 cells after exposure to PFOA for 72 h but SREBPs were not activated in vitro. These results demonstrated that SREBPs were maturated by activating the miR-183-96-182 cluster-SREBP regulatory loop in PFOA-exposed mouse liver.