The ligands/activators for peroxisome proliferator-activated receptor α (PPARα) and PPARγ increase Cu2+, Zn2+-superoxide dismutase and decrease p22phox message expressions in primary endothelial cells

Abstract

We examined the effects of a variety of ligands/activators of the peroxisome proliferator-activated receptor (PPAR) on the expression of the superoxide scavenger enzyme, Cu2+,Zn2+-superoxide dismutase (CuZn-SOD), and the superoxide generating enzyme nicotinamide adenine dinucleotide phosphate (reduced form) (NADPH) oxidase in primary cultures of human umbilical vein endothelial cells (HUVEC) and human aorta endothelial cells (HAEC). Our data show that 3 types of PPARs, PPARα, PPARβ/δ/Nuc1, and PPARγ are expressed in endothelial cells. Bezafibrate, which is a ligand/activator for PPARα, increased the CuZn-SOD gene expression and protein levels in endothelial cells. Troglitazone and pioglitazone, which are ligands/activators for PPARγ, also induced PPARα gene and protein expression and increased CuZn-SOD gene expression and protein levels in addition to increasing PPARγ gene and protein expression in endothelial cells. Moreover, with treatment of monounsaturated and polyunsaturated fatty acids (PUFA), the CuZn-SOD mRNA levels were positively correlated with PPARα mRNA levels (r = .872, P < .0001) in primary endothelial cells. In addition, the phorbol myristate acetate (PMA)-stimulated or PMA-nonstimulated 22-kd a-subunit (p22phox) mRNA levels and 47-kd a-subunit (p47phox) protein levels in NADPH oxidase were decreased by treatment with PPARα and PPARγ ligands/activators. These results suggest that PPARα and PPARγ gene and protein expression in endothelial cells may play a physiologic role as radical scavengers, although the details of these mechanisms remain to be established.