Glutathione peroxidase 2, the major cigarette smoke-inducible isoform of GPX in lungs, is regulated by Nrf2

Anju Singh, Tirumalai Rangasamy, Rajesh K. Thimmulappa, Hannah Lee, William O. Osburn, Regina Brigelius-Flohé, Thomas W. Kensler, Masayuki Yamamoto, Shyam Biswal

Research output: Contribution to journalArticlepeer-review

162 Citations (Scopus)

Abstract

Disruption of NF-E2-related factor (Nrf2), a redox-sensitive basic leucine zipper transcription factor, causes early-onset and more severe emphysema due to chronic cigarette smoke. Nrf2 determines the susceptibility of lungs to cigarette smoke-induced emphysema in mice through the transcriptional induction of numerous anti-oxidant genes. The lungs of Nrf2-/- mice have higher oxidative stress as evident from the increased levels of lipid peroxidation (4-hydroxy-2-nonenal) and oxidative DNA damage (7,8-dihydro-8-Oxo- 2′deoxyguanosine) in response to cigarette smoke. Glutathione peroxidases (GPX) are the primary antioxidant enzymes that scavenge hydrogen peroxide and organic hydroperoxides. Among the five GPX isoforms, expression of GPX2 was significantly induced at both mRNA and protein levels in the lungs of Nrf2+/+ mice, in response to cigarette smoke. Activation of Nrf2 by specific knock down of the cytosolic inhibitor of Nrf2, Keap1, by small inhibitory RNA (siRNA) upregulated the expression of GPx2, whereas Nrf2 siRNA down-regulated the expression of GPX2 in lung epithelial cells. An ARE sequence located in the 5′ promoter-flanking region of exon 1 that is highly conserved between mouse, rat, and human was identified. Mutation of this ARE core sequence completely abolished the activity of promoter-reporter gene construct. The binding of Nrf2 to the GPX2 antioxidant response element was confirmed by chromatin immunoprecipation, electrophoretic mobility shift assays, and site-directed mutagenesis. This study shows that GPX2 is the major oxidative stress-inducible cellular GPX isoform in the lungs, and that its basal as well as inducible expression is dependent on Nrf2.

Original languageEnglish
Pages (from-to)639-650
Number of pages12
JournalAmerican journal of respiratory cell and molecular biology
Volume35
Issue number6
DOIs
Publication statusPublished - 2006 Dec

Keywords

  • Antioxidant response element
  • Cigarette smoke
  • Emphysema
  • GPX2
  • Nrf2

ASJC Scopus subject areas

  • Molecular Biology
  • Pulmonary and Respiratory Medicine
  • Clinical Biochemistry
  • Cell Biology

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