FIGURE 7:
The TCF7L2/β-catenin transcriptional activity is up-regulated by PrPc and down-regulated by γ-catenin. (A) COS7 cells were transfected with luciferase reporter plasmids containing TCF-binding sites (TOP) or mutated TCF-binding sites as negative control (FOP) and a LacZ expression plasmid as internal control. Expression vectors for constitutively active S33Y mutant of β-catenin (β-cat*), PrPc, or γ-catenin were cotransfected as indicated. Values represent mean ± SEM of luciferase activity normalized to corresponding β-Gal activity. **p < 0.01; ***p < 0.001 vs. β-cat* alone. (B) SW480 cells were transfected with the TOP/FOP reporters and LacZ plasmid and cotransfected with empty vector (control) or PrPc or γ-catenin expression plasmids as indicated. **p < 0.01, ***p < 0.001 vs. control. (C) SW480 cells were transfected with the TOP/FOP reporters and LacZ plasmid, together with a control siRNA (siCtl), PrPc siRNAs (siPrP), or PrPc siRNAs combined with a mouse PrPc expression vector (siPrP+PrPc). **p < 0.01, ***p < 0.001 vs. siCtl; $$$p < 0.001 vs. siPrP. Experiments were all performed in triplicate, and the graphs present one experiment representative of two or three independent experiments for each condition.