gamma-Glutamyl transpeptidase is induced by 4-hydroxynonenal via EpRE/Nrf2 signaling in rat epithelial type II cells

Free Radic Biol Med. 2006 Apr 15;40(8):1281-92. doi: 10.1016/j.freeradbiomed.2005.11.005. Epub 2005 Dec 1.

Abstract

gamma-Glutamyl transpeptidase (GGT) plays key roles in glutathione homeostasis and metabolism of glutathione S-conjugates. Rat GGT is transcribed via five tandemly arranged promoters into seven transcripts. The transcription of mRNA V is controlled by promoter 5. Previously we found that GGT mRNA V-2 was responsible for the induction of GGT in rat alveolar epithelial cells by 4-hydroxynonenal (HNE). In the current study, the underlying mechanism was investigated. Reporter deletion and mutation analysis demonstrated that an electrophile-response element (EpRE) in the proximal region of GGT promoter 5 (GP5) was responsible for the basal- and HNE-induced promoter activity. Gel-shift assays showed an increased binding activity of GP5 EpRE after HNE exposure. The nuclear content of NF-E2-related factor 2 (Nrf2) was significantly increased by HNE. The recruitment of Nrf2 to GP5 EpRE after HNE treatment was demonstrated by supershift and chromatin immunoprecipitation assays. The tissue expression pattern of GGT mRNA V was previously unknown. Using polymerase chain reaction, we found that GGT mRNA V-2 was expressed in many tissues in rat. Taken together, GGT mRNA V-2 is widely expressed in rat tissues and its basal and HNE-induced expression is mediated through EpRE/Nrf2 signaling.

MeSH terms

  • Active Transport, Cell Nucleus
  • Aldehydes / pharmacology*
  • Animals
  • Base Sequence
  • Cell Line
  • Epithelial Cells / drug effects*
  • Epithelial Cells / metabolism*
  • Gene Expression
  • Molecular Sequence Data
  • Mutation / genetics
  • NF-E2-Related Factor 2 / metabolism*
  • Promoter Regions, Genetic / genetics
  • RNA, Messenger / genetics
  • Rats
  • Response Elements
  • Signal Transduction / drug effects*
  • gamma-Glutamyltransferase / genetics
  • gamma-Glutamyltransferase / metabolism*

Substances

  • Aldehydes
  • NF-E2-Related Factor 2
  • Nfe2l2 protein, rat
  • RNA, Messenger
  • gamma-Glutamyltransferase
  • 4-hydroxy-2-nonenal