Overexpression of Phospholipid Hydroperoxide Glutathione Peroxidase Suppressed Cell Death Due to Oxidative Damage in Rat Basophile Leukemia Cells (RBL-2H3)

Abstract

The role of phospholipid hydroperoxide glutathione peroxidase (PHGPx) in the cellular defense against oxidative stress was investigated in a novel cell model. We isolated stable transfectants of RBL-2H3 cells that overexpressed PHGPx. The activity of PHGPx in RBL2H3 cells that had been transfected with the 761bp cDNA for rat PHGPx (RPHGPx2) that we had cloned previously was 3.8 times higher than that in parent cells and in cells that had been mock-transfected with the vector without a cDNA insert. Cells that overexpressed PHGPx were three times more resistant than parent cells and mock-transfected cells to the cytotoxic effects of an radical initiator (AAPH) that induced the oxidative stress. This resistance to damage by AAPH of cells that overexpressed PHGPx was not observed after pretreatment with buthionine sulfoximine (BSO), an inhibitor of the synthesis of glutathione. Overexpression of PHGPx could suppress the peroxidation of membrane lipids and, in particular, the production of phosphatidylcholine hydroperoxide by AAPH in RBL2H3 cells. PHGPx was also able to prevent cell death in response to extracellular attack by a lipid peroxide. This is the first report to indicate directly that PHGPx can scavenge phosphatidylcholine hydroperoxide, which induces oxidative damage at the cellular level.