The GI-GPx gene is a target for Nrf2.
The gastrointestinal glutathione peroxidase (GI-GPx, GPx2) is a selenoprotein that was suggested to act as barrier against hydroperoxide absorption but has also been implicated in the control of inflammation and malignant growth. In CaCo-2 cells, GI-GPx was induced by t-butyl hydroquinone (tBHQ) and sulforaphane (SFN), i.e., "antioxidants" known to activate the "antioxidant response element" (ARE) via electrophilic thiol modification of Keap1 in the Nrf2/Keap1 system. The functional significance of a putative ARE in the GI-GPx promoter was validated by transcriptional activation of reporter gene constructs upon exposure to electrophiles (tBHQ, SFN, and curcumin) or overexpression of Nrf2 and by reversal of these effects by mutation of the ARE in the promoter and by overexpressed Keap1. Binding of Nrf2 to the ARE sequence in authentic gpx2 was corroborated by chromatin immunoprecipitation. Thus, the presumed natural antioxidants sulforaphane and curcumin may exert their anti-inflammatory and anticarcinogenic effects not only by induction of phase 2 enzymes but also by the up-regulation of the selenoprotein GI-GPx.
Banning
Antje
A
German Institute of Human Nutrition, Potsdam-Rehbruecke, Dept. of Biochemistry and Micronutrients, Arthur-Scheunert-Allee 114-116, D-14558 Nuthetal, Germany.
Deubel
Stefanie
S
Kluth
Dirk
D
Zhou
Zewen
Z
Brigelius-Flohé
Regina
R
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism; D016588:Anticarcinogenic Agents / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism; D045744:Cell Line, Tumor; D003474:Curcumin / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D005979:Glutathione Peroxidase / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D006873:Hydroquinones / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D017879:Isothiocyanates; D000072019:Kelch-Like ECH-Associated Protein 1; D051267:NF-E2-Related Factor 2; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D020218:Response Elements; D013454:Sulfoxides; D013861:Thiocyanates / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D016588:Anticarcinogenic Agents; D000975:Antioxidants; D004268:DNA-Binding Proteins; D006873:Hydroquinones; D047908:Intracellular Signaling Peptides and Proteins; D017879:Isothiocyanates; C431364:KEAP1 protein, human; D000072019:Kelch-Like ECH-Associated Protein 1; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D011506:Proteins; D013454:Sulfoxides; D013861:Thiocyanates; D015534:Trans-Activators; C018855:2-tert-butylhydroquinone; C117436:GPX2 protein, human; D005979:Glutathione Peroxidase; C016766:sulforaphane; D003474:Curcumin