Increased expression of uncoupling protein 2 in HepG2 cells attenuates oxidative damage and apoptosis

Abstract

Oxidative damage plays a major part in the pathogenesis of liver disease. Uncoupling proteins (UCPs) may be able to limit the generation of reactive oxygen species (ROS) and be cytoprotective. We investigated the effect of up-regulation of UCP2 in a hepatoblastoma cell line exposed to menadione or hypoxia/re-oxygenation. Lipid and protein oxidation was increased in HepG2 cells exposed to ROS but this increase was significantly lower in cells over-expressing UCP2 under identical conditions. LDH release increased 2.5-fold in response to hypoxia/re-oxygenation in control HepG2 cells with no significant increase in UCP2 transfected cells. Hypoxia/re-oxygenation resulted in a reduction in liver-specific protein secretion that was attenuated in transfected cells and UCP2 over-expression also resulted in a 66% reduction in apoptosis compared with non-transfected controls. These data suggest that UCP2 can limit oxidative damage in HepG2 cells in response to oxidative stress resulting in improved cell function and resistance to apoptosis.