Selenium supplementation of lung epithelial cells enhances nuclear factor E2-related factor 2 (Nrf2) activation following thioredoxin reductase inhibition

Redox Biol. 2018 Oct;19:331-338. doi: 10.1016/j.redox.2018.07.020. Epub 2018 Sep 5.

Abstract

The trace element selenium (Se) contributes to redox signaling, antioxidant defense, and immune responses in critically ill neonatal and adult patients. Se is required for the synthesis and function of selenoenzymes including thioredoxin (Trx) reductase-1 (TXNRD1) and glutathione peroxidases (GPx). We have previously identified TXNRD1, primarily expressed by airway epithelia, as a promising therapeutic target to prevent lung injury, likely via nuclear factor E2-related factor 2 (Nrf2)-dependent mechanisms. The present studies utilized the TXNRD1 inhibitor auranofin (AFN) to test the hypothesis that Se positively influences Nrf2 activation and selenoenzyme responses in lung epithelial cells. Murine transformed Club cells (mtCCs) were supplemented with 0, 10, 25, or 100 nM Na2SeO3 to create a range of Se conditions and were cultured in the presence or absence of 0.5 μM AFN. TXNRD1 and GPX2 protein expression and enzymatic activity were significantly greater upon Se supplementation (p < 0.05). AFN treatment (0.5 μM AFN for 1 h) significantly inhibited TXNRD1 but not GPx activity (p < 0.001). Recovery of TXNRD1 activity following AFN treatment was significantly enhanced by Se supplementation (p < 0.041). Finally, AFN-induced Nrf2 transcriptional activation was significantly greater in mtCCs supplemented in 25 or 100 nM Na2SeO3 when compared to non-supplemented controls (p < 0.05). Our novel studies indicate that Se levels positively influence Nrf2 activation and selenoenzyme responses following TXNRD1 inhibition. These data suggest that Se status significantly influences physiologic responses to TXNRD1 inhibitors. In conclusion, correction of clinical Se deficiency, if present, will be necessary for optimal therapeutic effectiveness of TXNRD1 inhibitors in the prevention of lung disease.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Line
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism
  • Glutathione Peroxidase / metabolism
  • Lung / cytology
  • Lung / drug effects*
  • Lung / metabolism
  • Mice
  • NF-E2-Related Factor 2 / metabolism*
  • Respiratory Mucosa / cytology
  • Respiratory Mucosa / drug effects*
  • Respiratory Mucosa / metabolism
  • Selenium / pharmacology*
  • Thioredoxin Reductase 1 / antagonists & inhibitors*
  • Thioredoxin Reductase 1 / metabolism

Substances

  • NF-E2-Related Factor 2
  • Nfe2l2 protein, mouse
  • Gpx2 protein, mouse
  • Glutathione Peroxidase
  • Thioredoxin Reductase 1
  • Txnrd1 protein, mouse
  • Selenium