Figure 3. p53 transcriptional regulation of TDG. (A) TE-13 cells were co-transfected with TDG-luciferase reporters and either increasing amounts of the expression vector for p53 (p53wt-pcDNA3) or with 2 μg of the control (empty) vector pcDNA3 (Ø). (B) TE-1 cells cultured at either 32°C or 37°C were treated with 0.25, 0.5 or 1.0 mM of methyl methanesulfonate (MMS) for 3 h and transfected with TDG-luciferase reporters and the luciferase assays were performed. Basic, promoterless luciferase reporter (pGL3 basic); p53RE1, luciferase reporter under the control of the 838 bp segment of TDG promoter containing the first p53RE; p53RE2/3, luciferase reporter under the control of the 1.5 kb segment of TDG promoter containing the second and the third p53REs. (C) The TDG-luciferase construct containing p53RE2/p53RE3 had either p53RE2, p53RE3 or both deleted by site-directed mutagenesis (as schematically shown in right panel) and mutated plasmids were co-transfected with 2 μg of expression vector for p53 (p53wt-pcDNA3) in TE-13 cells and the luciferase assays performed. Del p53RE2, plasmids harboring the deletion of p53RE2; Del p53RE3, plasmids harboring the deletion of p53RE3; Del p53RE2/3, plasmids harboring the deletion of p53RE2 and 3. Stars indicate statistical significance: *p < 0.05 (Student’s t-test was performed with software GraphPad Prism 4, GraphPad Software Inc.).