Hyperoxia stimulates an Nrf2-ARE transcriptional response via ROS-EGFR-PI3K-Akt/ERK MAP kinase signaling in pulmonary epithelial cells

Antioxid Redox Signal. Jan-Feb 2006;8(1-2):43-52. doi: 10.1089/ars.2006.8.43.

Abstract

Nuclear factor erythroid 2-related factor (Nrf2) confers protection against cell death induced by hyperoxia and other proapoptotic stimuli. Because phosphoinositide-3-kinase (PI3K)/Akt signaling promotes cell survival, the significance of this pathway in mediating reactive oxygen species (ROS)-dependent hyperoxia-induced Nrf2 activation was investigated in the murine pulmonary epithelial cell line, C10. Inhibition of the PI3K pathway markedly attenuated hyperoxia-induced Nrf2 translocation and ARE (antioxidant response element)-mediated transcription. Consistent with this, hyperoxia markedly stimulated the activation of PI3K pathway, while an NADPH oxidase inhibitor and an antioxidant prevented such activation. The inhibition of Akt activity using a pharmacological inhibitor markedly attenuated Nrf2 translocation and ARE-driven expression. Moreover, overexpression of a dominant-negative Akt mutant attenuated the transcription, whereas a constitutively active mutant stimulated it. These results suggest that PI3K/Akt signaling regulates Nrf2 activation by hyperoxia. Inhibition of the PI3K pathway prevented hyperoxia-stimulated Akt and ERK1/2 kinase activation, which is critical for Nrf2-mediated transcription. Likewise, the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, AG1478, blocked hyperoxia-stimulated Akt and ERK1/2 phosphorylation, Nrf2 nuclear accumulation, and ARE-driven transcription. Consistent with this result, an NADPH oxidase inhibitor blocked hyperoxia- stimulated EGFR phosphorylation, which was correlated with the attenuation of Akt and ERK activation. Collectively, our data suggest that EGFR-PI3K signaling through Akt and ERK kinases regulates ROS-dependent, hyperoxia-induced Nrf2 activation in pulmonary epithelial cells.

Publication types

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

MeSH terms

  • Animals
  • Cell Line
  • ErbB Receptors / physiology*
  • Hyperoxia / physiopathology*
  • Hyperoxia / prevention & control
  • Immunohistochemistry
  • MAP Kinase Signaling System / physiology*
  • Mice
  • Models, Biological
  • NF-E2-Related Factor 2 / metabolism*
  • Oxidative Stress / physiology*
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Pulmonary Alveoli / physiology*
  • Respiratory Mucosa / physiology*
  • Transcription, Genetic*

Substances

  • NF-E2-Related Factor 2
  • Phosphatidylinositol 3-Kinases
  • ErbB Receptors
  • Proto-Oncogene Proteins c-akt