Functional analysis of phospholipid hydroperoxide glutathione peroxidase by targeting its expression

Phospholipid hydroperoxide glutathione peroxidase (also known as PHGPX or GPx4) is an essential mammalian protein that functions as both an oxidoreductase enzyme and a structural protein. It acts on a range of substrates from hydrogen peroxide to lipid hydroperoxides and has increased affinity for phospholipid hydroperoxides. To better elucidate the function of GPx4, we used RNAi technology to knockdown its expression in NIH3T3 cells. GPx4 knockdown cells grew more than 70% slower than control cells, developed a dendrite‐like structure and died abruptly after several passages providing evidence that GPx4 is essential for cell survival. The dendrite‐like phenotype suggests that the knockdown cells underwent significant changes in their plasma membrane structure. Since lipid hydroperoxides are known to be potent cytotoxins, we examined the cytoprotective mechanism of GPx4 against these compounds by investigating membrane lipid composition of GPx4 knockdown and control cells. The data provide important insights into GPx4 function beyond its role as a detoxification enzyme.