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Role of Nrf2 in the regulation of the Mrp2 (ABCC2) gene.
- Source :
-
The Biochemical journal [Biochem J] 2006 May 01; Vol. 395 (3), pp. 599-609. - Publication Year :
- 2006
-
Abstract
- The Nrf2 (nuclear factor-erythroid 2 p45-related factor 2) transcription factor regulates gene expression of the GCLC (glutamate-cysteine ligase catalytic subunit), which is a key enzyme in glutathione synthesis, and GSTs (glutathione S-transferases) via the ARE (antioxidant-response element). The Mrp2 (multidrug-resistance protein 2) pump mediates the excretion of GSH and GSSG excretion as well as endo- and xeno-biotics that are conjugated with GSH, glucuronate or sulphate. Considering that Mrp2 acts synergistically with these enzymes, we hypothesized that the regulation of Mrp2 gene expression is also dependent on Nrf2. Using BHA (butylated hydroxyanisole), which is a classical activator of the ARE-Nrf2 pathway, we observed an increase in the transcriptional activity of Mrp2, GCLC and Gsta1/Gsta2 genes in the mouse liver. A similar pattern of co-induction of Mrp2 and GCLC genes was also observed in mouse (Hepa 1-6) and human (HepG2) hepatoma cells treated with BHA, beta-NF (beta-naphthoflavone), 2,4,5-T (trichlorophenoxyacetic acid) or 2AAF (2-acetylaminofluorene), suggesting that these genes share common mechanism(s) of transcriptional activation in response to exposure to xenobiotics. To define the mechanism of Mrp2 gene induction, the 5'-flanking region of the mouse Mrp2 gene (2.0 kb) was isolated, and two ARE-like sequences were found: ARE-2 (-1391 to -1381) and ARE-1 (-95 to -85). Deletion analyses demonstrated that the proximal region (-185 to +99) contains the elements for the basal expression and xenobiotic-mediated induction of the Mrp2 gene. Gel-shift and supershift assays indicated that Nrf2-protein complexes bind ARE sequences of the Mrp2 promoter, preferentially to the ARE-1 sequence. Overexpression of Nrf2 increased ARE-1-mediated CAT (chloramphenicol acetyltransferase) gene activity, while overexpression of mutant Nrf2 protein repressed the activity. Thus Nrf2 appears to regulate Mrp2 gene expression via an ARE element located at the proximal region of its promoter in response to exposure to xenobiotics.
- Subjects :
- 5' Flanking Region genetics
Animals
Antioxidants metabolism
Base Sequence
Bile drug effects
Bile metabolism
Butylated Hydroxyanisole pharmacology
Catalytic Domain
Cell Line, Tumor
Conserved Sequence
Female
Gene Deletion
Gene Expression Regulation drug effects
Genes, Reporter genetics
Glutamate-Cysteine Ligase genetics
Glutamate-Cysteine Ligase metabolism
Glutathione Transferase genetics
Glutathione Transferase metabolism
Humans
Isoenzymes genetics
Isoenzymes metabolism
Liver drug effects
Liver metabolism
Mice
Mitochondrial Proteins metabolism
Molecular Sequence Data
Multidrug Resistance-Associated Protein 2
NF-E2-Related Factor 2 genetics
Protein Binding
Response Elements genetics
Ribosomal Proteins metabolism
Saccharomyces cerevisiae Proteins metabolism
Sequence Alignment
Transcriptional Activation
beta-Naphthoflavone pharmacology
Gene Expression Regulation genetics
Mitochondrial Proteins genetics
NF-E2-Related Factor 2 metabolism
Ribosomal Proteins genetics
Saccharomyces cerevisiae Proteins genetics
Subjects
Details
- Language :
- English
- ISSN :
- 1470-8728
- Volume :
- 395
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- The Biochemical journal
- Publication Type :
- Academic Journal
- Accession number :
- 16426233
- Full Text :
- https://doi.org/10.1042/BJ20051518