Serine 32 targeted mutation abolishes Prdx6 trafficking to lamellar bodies in vivo

Abstract

Peroxiredoxin 6 (Prdx6), a protein with both GSH peroxidase and phospholipase A2 (aiPLA2) activities, participates in lung surfactant phospholipid (PL) turnover and protects lung epithelium from oxidative stress. Prdx6 null mice accumulate PL in lung tissue, compatible with the role of PLA2 activity in lung phospholipid turnover. Prdx6 has been localized to cytosolic and acidic compartments (lamellar bodies (LB) and lysosomes) in lung epithelium. Our previous studies indicated that serine at position 32 (S32) is necessary for proper Prdx6 targeting to LB. We have generated a mouse model with an S32T mutation in the Prdx6 LB targeting sequence. Homozygous mice carrying the S32T mutation exhibited phospholipid (PL) accumulation in LB (PL/protein ratio 14.36) vs. WT (PL/protein ratio 9.51). Western blot analysis demonstrated absence of Prdx6 in LBs isolated from S32T mice despite equal amounts of Prdx6 in lung homogenates. Immunofluorescence analysis of mouse lung tissue sections showed co‐localization of Prdx6 with LAMP1, a marker of lysosome‐related organelles, in wild type but not in S32T mouse alveolar type II cells. These findings indicate that S32 is required for Prdx6 targeting to LB in mouse lung epithelium. [HL102016 and HL19737]