Relationship between signal transduction and PPAR alpha-regulated genes of lipid metabolism in rat hepatic-derived Fao cells.

The goal of this study was to characterize phosphorylated proteins and to evaluate the changes in their phosphorylation level under the influence of a peroxisome proliferator (PP) with hypolipidemic activity of the fibrate family. The incubation of rat hepatic derived Fao cells with ciprofibrate leads to an overphosphorylation of proteins, especially one of 85 kDa, indicating that kinase (or phosphatase) activities are modified. Moreover, immunoprecipitation of 32P-labeled cell lysates shows that the nuclear receptor, PP-activated receptor, alpha isoform, can exist in a phosphorylated form, and its phosphorylation is increased by ciprofibrate.

Ciprofibrate stimulates protein kinase C-dependent phosphorylation of an 85 kDa protein in rat Fao hepatic derived cells.

The effect of ciprofibrate on early events of signal transduction was previously studied in Fao cells. Protein kinase C (PKC) assays performed on permeabilized cells showed a more than two-fold increase in PKC activity in cells treated for 24 h with 500 microM ciprofibrate. To show the subsequent effect of this increase on protein phosphorylation, the in vitro phosphorylation on particulate fractions obtained from Fao cells was studied.

Vitamin E mediated response of smooth muscle cell to oxidant stress.

Oxidant stress is associated with diminution of antioxidant molecules, such as alpha-tocopherol. Alpha-tocopherol specifically decreases, in a concentration dependent way, the proliferation of vascular smooth muscle cells. At the same concentrations (10-50 microM) it induces inhibition of protein kinase C (PKC) activity.

Phosphorylation of peroxisome proliferator-activated receptor alpha in rat Fao cells and stimulation by ciprofibrate.

The basic mechanism(s) by which peroxisome proliferators activate peroxisome proliferator-activated receptors (PPARs) is (are) not yet fully understood. Given the diversity of peroxisome proliferators, several hypotheses of activation have been proposed. Among them is the notion that peroxisome proliferators could activate PPARs by changing their phosphorylation status.