Nrf2 possesses a redox-sensitive nuclear exporting signal in the Neh5 transactivation domain

NF-E2-related factor 2 (Nrf2) is the key transcription factor regulating the antioxidant response. Previous studies identified a nuclear localization signal (NLS) in the basic region and a nuclear exporting signal (NES) in the leucine zipper domain of Nrf2. In this study, we characterize a new functional NES (¹⁷⁵LLSIPELQCLNI¹⁸⁶) in the transactivation (TA) domain of Nrf2. A green fluorescence protein (GFP)-tagged Nrf2 segment (amino acids162-295) called GFP-NES_TA exhibited a cytosolic distribution that could be disrupted by L184A mutation or leptomycin B treatment. Chimeric expression of this NES_TA with a nuclear protein GAL4DBD could expel GAL4DBD into the cytoplasm. A variety of oxidants, including sulforaphane, tert-butylhydroquinone, and H₂O₂, could effectively induce nuclear translocation of GFP-NES_TA. Mutational studies showed that cysteine 183 may mediate the redox response of NES_TA. The discovery of multiple NLS/NES motifs in Nrf2 and the redox sensitivity of NES_TA imply Nrf2 may be self-sufficient to sense and transduce oxidative signals into the nucleus, consequently initiating antioxidant gene transcription.