Suzuki, T., Takagi, Y., Osanai, H., Li, L., Takeuchi, M., Katoh, Y., Kobayashi, M., and Yamamoto, M. (2005) Pi class glutathione S-transferase genes are regulated by Nrf 2 through an evolutionarily conserved regulatory element in zebrafish. The Biochemical journal. 388(Pt 1):65-73.
Pi-class glutathione S-transferases (GST) is a member of the vertebrate GST family of proteins that catalyze the conjugation of reduced glutathione to electrophilic compounds. The expression of Pi-class GST genes can be induced by exposure to electrophiles. We demonstrated previously that the transcription factor Nrf2 mediates this induction, not only in mammals, but also in fish. In the present study, we have isolated the genomic region of zebrafish containing the genes gstp1 and gstp2. The regulatory regions of zebrafish gstp1 and gstp2 have been examined by GFP-reporter gene analyses using microinjection into zebrafish embryos. Deletion and point-mutation analyses of the gstp1 promoter showed that an antioxidant responsive element (ARE)-like sequence is located 50 bp upstream of the transcription initiation site which is essential for Nrf2 transactivation. Using electrophoretic mobility shift assay we showed that zebrafish Nrf2-MafK heterodimer specifically bound to this sequence. All the vertebrate Pi-class GST genes harbor a similar ARE-like sequence in their promoter regions. We propose that this sequence is a conserved target site for Nrf2 in the Pi-class GST genes.