Critical role of peroxiredoxin 6 in the repair of peroxidized cell membranes following oxidative stress

Phospholipids are a major structural component of all cell membranes; their peroxidation represents a severe threat to cellular integrity and their repair is important to prevent cell death. Peroxiredoxin 6 (Prdx6), a protein with both GSH peroxidase and phospholipase A(2) (PLA(2)) activity, plays a critical role in antioxidant defense of the lung and other organs. We investigated the role of Prdx6 in the repair of peroxidized cell membranes in pulmonary microvascular endothelial cells (PMVEC) and isolated mouse lungs treated with tert-butyl hydroperoxide and lungs from mice exposed to hyperoxia (100% O-2). Lipid peroxidalion was evaluated by measurement of Lhiobarbiluric acid reaclive substances, oxidation of dipheny1-1-pyrenylphosphine, or ferrous xylenol orange assay. The exposure dose was varied to give a similar degree of lipid peroxidalion at the end of exposure in the different models. Values for lipid peroxidalion returned to control levels within 2 h after oxidant removal in wild type PMVEC and per fused lungs but were unchanged in Pxclx6 null preparations. An intermediate degree of repair was observed with PMVEC and Icings that expressed only C47S or D140A mutant Prclx6; the former mutant does not have peroxidase activity, while the latter loses its PLA2 activity. Prclx6 null mice showed markedly delayed recovery born lipid peroxidation during 20 h observation following exposure to hyperoxia. Thus, Prdx6 plays a critical role in the repair of peroxidized phospholipids in cell membranes and the recovery of lung cells from peroxidative stress; the peroxidase and PLA2 activity each contribute to the recovery process. (C) 2015 Published by Elsevier Inc.