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A6352 - Nuclear Thioredoxin-1 Potentiates Inflammatory Signaling and Cell Death During Hyperoxic Injury
Author Block: P. Vitiello1, B. Forred1, M. Floen1, M. Booze1, J. Cain2, A. Fairchild1, S. Baack1, A. Ashbacher1, E. Fale1, J. Weimer2, Y. Go3; 1Environmental Influences on Health and Disease Group, Sanford Research, Sioux Falls, SD, United States, 2Pediatrics and Rare Diseases Group, Sanford Research, Sioux Falls, SD, United States, 3Pulmonary, Allergy and Critical Care Medicine, Emory University, Atlanta, GA, United States.
Increased atmospheric oxygen tension, hyperoxia, contributes to the pathogenesis of bronchopulmonary dysplasia (BPD). Although oxygen-dependent signaling pathways regulating pulmonary epithelial responses during oxidative injury are well described, there is limited knowledge on the regulation of redox-sensitive modifications and signaling. Reversible non-radical cysteine modifications serve as a redox-dependent interface to sense and initiate signaling pathways in response to oxidative perturbations. Thioredoxin-1 (Trx1) is a major thiol oxidoreductase that catalyzes reduction of oxidized cysteine thiols of redox-dedicated enzymes as well as non-redox substrates. Although Trx1 is cytoprotective against hyperoxic injury and predominantly resides in the cytosol, nuclear Trx1 accumulation has been reported to occur during oxidative stress. The objective of this study was to investigate molecular and physiological functions of nuclear Trx1 during hyperoxic injury. We found that nuclear Trx1 increased in human adenocarcinoma H1299 and A549 cells cultured under hyperoxic conditions (95% O2 and 5% CO2) by performing subcellular fractionation and immunocytochemistry. Similarly, nuclear Trx1 was significantly increased in hyperoxic mouse lungs. Therefore, we manipulated subcellular expression of Trx1 to understand how nuclear Trx1 influences oxygen-dependent injury pathways. Expression of a nuclear-targeted Trx1 transgene exacerbated hyperoxic death of H1299 cells. This was effect was lost when the redox-active site of Trx1 was mutated or Trx1 localization was restricted to the cytosol. Adult mice with ubiquitous expression of a nuclear-targeted Trx1 had increased proteinaceous edema and pulmonary expression of TNF-α, IL-2, IL-4 and IL-10 after hyperoxic treatment. To elucidate potential Trx1-dependent signaling pathways, we used a substrate-trap for proteomic identification of Trx1 protein interactions in the nuclear compartment during hyperoxic treatment of H1299 cells. This approach identified 15 oxygen-sensitive protein candidates regulated by Trx1 that function in gene regulatory or stress signaling pathways. Taken together, these data support that nuclear Trx1 can modulate lung epithelial physiologies in response to increased atmospheric oxygen tension (cell death and inflammatory signaling) and warrants further investigation of nuclear Trx1 as an enzymatic regulator of redox-dependent signaling pathways influencing BPD pathogenesis.