Nrf2 mediates the induction of ferritin H in response to xenobiotics and cancer chemopreventive dithiolethiones.
Ferritin is a ubiquitous intracellular iron storage protein that consists of 24 subunits of the H and L type. The ability to sequester iron from participation in oxygen free radical formation is consistent with a cytoprotective role for ferritin. Here we demonstrate that ferritins H and L are induced in cells treated with beta-napthoflavone (beta-NF) and chemopreventive dithiolethiones. Induction of ferritin H by beta-NF and the dithiolethiones oltipraz and 1,2-dithiole-3-thione (D3T) occurs via a transcriptional mechanism that is mediated by the ferritin H electrophile/antioxidant-responsive element (EpRE/ARE). The murine ferritin H gene contains five potential xenobiotic-responsive element (XRE) sequences in its 5'-promoter region. However, deletion analysis demonstrates that these XRE sequences are not functional in inducing ferritin H in response to beta-NF. Electrophoretic mobility shift assays demonstrate that the ferritin H EpRE/ARE binds Nrf2. Transfection of chimeric ferritin H reporter genes with Nrf2 expression vectors and Nrf2 dominant-negative mutants indicate that Nrf2 functions at the EpRE/ARE to mediate transcriptional activation of ferritin H. Induction of ferritin H and L was not seen in Nrf2 knockout cells, demonstrating that this transcription factor is required for the induction of ferritin in response to polycyclic aromatic xenobiotics and chemopreventive agents. Nrf2 may also play a role in basal transcription of both ferritin H and L. These results provide a mechanistic link between regulation of the iron storage protein ferritin and the cancer chemopreventive response.
Pietsch
E Christine
EC
Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
Chan
Jefferson Y
JY
Torti
Frank M
FM
Torti
Suzy V
SV
D016475:3T3 Cells; D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology; D001483:Base Sequence; D015152:Blotting, Northern; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005293:Ferritins / Q000737:chemistry* / Q000378:metabolism*; D017353:Gene Deletion; D017930:Genes, Reporter; D006801:Humans; D007501:Iron / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D008957:Models, Genetic; D008969:Molecular Sequence Data; D051267:NF-E2-Related Factor 2; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011719:Pyrazines / Q000494:pharmacology; D020218:Response Elements; D013871:Thiones / Q000494:pharmacology; D013876:Thiophenes / Q000494:pharmacology; D013997:Time Factors; D015534:Trans-Activators / Q000502:physiology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured; D015262:Xenobiotics / Q000494:pharmacology; D019324:beta-Naphthoflavone / Q000494:pharmacology
D016588:Anticarcinogenic Agents; D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; C495636:Nfe2l2 protein, mouse; D011719:Pyrazines; D013871:Thiones; D013876:Thiophenes; D015534:Trans-Activators; D015262:Xenobiotics; D019324:beta-Naphthoflavone; C026209:oltipraz; D005293:Ferritins; D007501:Iron; C049325:1,2-dithiol-3-thione