Ferritin gene transcription is regulated by heme as is ferritin mRNA 
translation, which is mediated by the well studied mRNA.IRE/IRP protein complex. 
The heme-sensitive DNA sequence in ferritin genes is the maf 
recognition/antioxidant response element present in several other genes that are 
induced by heme and repressed by Bach1. We now report that chromatin 
immunoprecipitated with Bach1 antiserum contains ferritin DNA sequences. In 
addition, overexpression of Bach1 protein in the transfected cells decreased 
ferritin expression, indicating insufficient endogenous Bach1 for full 
repression; decreasing Bach1 with antisense RNA increased ferritin expression. 
Thioredoxin reductase1, a gene that also contains a maf recognition/antioxidant 
response element but is less studied, responded similarly to ferritin, as did 
the positive controls heme oxygenase1 and NADP(H) quinone (oxido) reductase1. 
Bach1-DNA promoter interactions in cells were confirmed in vitro with soluble, 
recombinant Bach1 protein and revealed a quantitative range of Bach1/DNA 
stabilities: ferritin L approximately ferritin H approximately beta-globin, 
beta-globin approximately 2-fold >heme oxygenase1 = quinone reductase 
beta-globin approximately 4-fold >thioredoxin reductase1. Such results indicate 
the possibility that modulation of cellular Bach1 concentrations will have 
variable effects among the genes coordinately regulated by maf 
recognition/antioxidant response elements in iron/oxygen/antioxidant metabolism.