Compartmentation of Nrf-2 redox control: regulation of cytoplasmic activation by glutathione and DNA binding by thioredoxin-1.
Nrf-2 is a redox-sensitive transcription factor that is activated by an oxidative signal in the cytoplasm but has a critical cysteine that must be reduced to bind to DNA in the nucleus. The glutathione (GSH) and thioredoxin (TRX) systems have overlapping functions in thiol/disulfide redox control in both the cytoplasm and the nucleus, and it is unclear whether these are redundant or have unique functions in control of Nrf-2-dependent signaling. To test whether GSH and Trx-1 have distinct functions in Nrf-2 signaling, we selectively modified GSH by metabolic manipulation and selectively modified Trx-1 expression by transient transfection. Cytoplasmic activation of Nrf-2 was measured by its nuclear translocation and nuclear activity of Nrf-2 was measured by expression of a luciferase reporter construct containing an ARE4 from glutamate cysteine ligase. Results showed that tert-butylhydroquinone (TBHQ), a transcriptional activator that functions through Nrf-2/ARE, promoted Nrf-2 nuclear translocation by a type I (thiylation) redox switch which was regulated by GSH not by Trx-1. In contrast, the ARE reporter was principally controlled by nuclear-targeted Trx-1 and not by GSH. The data show that the GSH and TRX systems have unique, compartmented functions in the control of transcriptional regulation by Nrf-2/ARE.
Department of Medicine and Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.
Jason M
JM
Hansen
Walter H
WH
Watson
Dean P
DP
Jones
D000111:Acetylcysteine / Q000494:pharmacology; D001665:Binding Sites; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D005978:Glutathione / Q000378:metabolism*; D006367:HeLa Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology; D051267:NF-E2-Related Factor 2; D010084:Oxidation-Reduction; D015398:Signal Transduction; D013879:Thioredoxins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015534:Trans-Activators / Q000096:biosynthesis*; D014162:Transfection
D004268:DNA-Binding Proteins; D006873:Hydroquinones; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; C491203:TXN protein, human; D015534:Trans-Activators; D019328:Buthionine Sulfoximine; D013879:Thioredoxins; D004247:DNA; C018855:2-tert-butylhydroquinone; D005978:Glutathione; D000111:Acetylcysteine