Figure 4. bZiP transcription factors regulate cat-1 gene transcription through the AARE.
(A) Constructs used in the present study. The PA1.4/UTR constructs contain 1.4 kb of cat-1 genomic DNA upstream of the transcription start site, the entire cat-1 mRNA leader and the LUC open reading frame. The transcription start site (arrow) and the open reading frame in the mRNA leader (upstream open reading frame) are shown. Point mutations are shown by shaded boxes. (B and C) C6 cells were transiently transfected with wild-type PA1.4/UTR (B) or the indicated PA1.4/UTR constructs (C) and plasmids encoding transcription factors. LUC activity was measured in extracts from fed cells. The graphs show the means±S.E.M. of LUC activity/μg protein from three independent samples normalized to the values in cells transfected with wild-type PA1.4/UTR without transcription factors. Significant differences from samples without transfected transcription factor are indicated: *P<0.01, **P<0.001.