Preterm infants and patients with
lung disease often have excess fluid in the lungs and are frequently treated with
oxygen, however long-term exposure to
hyperoxia results in irreversible
lung injury. Although the adverse effects of
hyperoxia are mediated by
reactive oxygen species, the full extent of the impact of
hyperoxia on redox-dependent regulation in the lung is unclear. In this study, neonatal mice overexpressing the beta-subunit of the
epithelial sodium channel (β-ENaC) encoded by Scnn1b and their wild type (WT; C57Bl6) littermates were utilized to study the pathogenesis of high fraction inspired
oxygen (FiO2)-induced
lung injury. Results showed that O2-induced
lung injury in transgenic Scnn1b mice is attenuated following chronic O2 exposure. To test the hypothesis that reversible
cysteine-redox-modifications of
proteins play an important role in O2-induced
lung injury, we performed
proteome-wide profiling of
protein S-glutathionylation (SSG) in both WT and Scnn1b overexpressing mice maintained at 21% O2 (normoxia) or FiO2 85% (
hyperoxia) from birth to 11-15 days postnatal. Over 7700 unique Cys sites with SSG modifications were identified and quantified, covering more than 3000
proteins in the lung. In both mouse models,
hyperoxia resulted in a significant alteration of the SSG levels of Cys sites belonging to a diverse range of
proteins. In addition, substantial SSG changes were observed in the Scnn1b overexpressing mice exposed to
hyperoxia, suggesting that ENaC plays a critically important role in cellular regulation.
Hyperoxia-induced SSG changes were further supported by the results observed for
thiol total oxidation, the overall level of reversible oxidation on
protein cysteine residues. Differential analyses reveal that Scnn1b overexpression may protect against
hyperoxia-induced
lung injury via modulation of specific processes such as cell adhesion, blood coagulation, and proteolysis. This study provides a landscape view of
protein oxidation in the lung and highlights the importance of redox regulation in O2-induced
lung injury.