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. 2006 Aug 21;26(21):7942–7952. doi: 10.1128/MCB.00700-06

FIG. 7.

FIG. 7.

TG repeats can be replaced with an alternative Z-DNA-forming sequence to sustain induction of the hHO-1 gene. (A) The sequence of the human HO-1 promoter with TG repeats. The numbers above and below the sequence are relative positions from the transcription start site (+1). (B) Schematic representation of the mutant reporter construct. Thirty TG repeats are replaced with 18 GC repeats or the NQO1 fifth exon (random). (C) Activities of the pCEP4 hHO-1 luc (WT), 18GC, and random constructs. The pCEP4 hHO-1 luc, 18GC, and random constructs were cotransfected with the Nrf2 expression plasmid into SW480 cells. The means of three independent experiments each carried out in duplicate are shown, and error bars represent SE. Luciferase activity in the WT HO-1 promoter reporter plasmid alone was set at 1. *, significantly different from the activity of the WT construct in the presence of the same amount of Nrf2 expression plasmid (P < 0.05). (D) Activities of the pCEP4 hHO-1 luc (WT), 18GC, and random constructs in response to DEM. The pCEP4 hHO-1 luc, 18GC, and random constructs were transfected into SW480 cells. After transfection, cells were treated with 100 μM DEM for 24 h. Luciferase activity in the WT HO-1 promoter-reporter plasmid in the absence of DEM was set at 1. The results are presented as described for panel C. *, significantly different from the activity of the WT construct in the presence of DEM (P < 0.05). (E) TG repeats can be replaced by GC repeats for activation of the HO-1 gene by BRG1. The 30 TG repeats in the HO-1 promoter in pCEP4 hHO-1 luc (WT) were replaced by 18 GC repeats (18GC) or sequence from the NQO1 fifth exon (random). SW13 cells were transfected with 20 ng of each reporter construct along with 100 ng of Nrf2 expression plasmid (white bars) or both with Nrf2 and 800 ng of BRG1 expression plasmids (black bars). Luc activity of each reporter construct cotransfected with Nrf2 expression plasmid alone was arbitrarily set at 1. *, significantly different from the activity of the WT construct in the presence of BRG1 (P < 0.05).