Both Peroxidase and Phospholipase A2 Activities of peroxiredoxin 6 Protect Against Oxidative Stress by Reduction of Peroxidized Cell Membranes

Abstract

Peroxiredoxin 6 (Prdx6), a protein with both peroxidase and PLA2 activities, plays a critical role in antioxidant defense of lung and other organs. We investigated the relative importance of these 2 activities of Prdx6 in the “repair” of peroxidized cell membranes in pulmonary microvascular endothelial cells (PMVECs) and isolated mouse lungs. Lipid peroxidation was evaluated by measurement of thiobarbituric acid reactive substances (TBARS) or oxidation of diphenyl‐1‐pyrenylphosphine (DPPP). PMVECs were treated with tert‐butyl hydroperoxide (tBOOH, 0.2 mM) or Cu2+ /ascorbate for 4 h and then evaluated at 0,2,4 and 6 h after removal of the oxidant. Values for lipid peroxidation returned to control levels in 2 h with wild type (WT) PMVECs but were unchanged at 6 h after oxidant removal in Pxdx6 null PMVECs. An intermediate degree of repair was observed with lentivirus transfected C47S or D140A mutant Prdx6 PMVECs; the former express only PLA2 activity and the latter only peroxidase activity. Similar results were obtained with the isolated mouse lungs from WT, Prdx6 null and Prdx6‐C47S or ‐D140A “knock‐in” mice that were observed for 3 h following 60 min of perfusion with 15 mM tBOOH. These results indicate that the peroxidase and phospholipase A2 activities of Prdx6 both play a critical role in the repair of peroxidized phospholipids in cell membranes and the recovery of lung cells from peroxidative stress.