FIG. 4.

Identification of a Wnt/Wg response element in the Xenopus fibronectin promoter. (A) Luciferase reporter gene constructs used in this study. Putative LEF-TCF binding sites are indicated as filled boxes. The asterisk marks a mutated LEF-TCF site (for sequence comparison, see Fig. 5A). (B) Promoter activities of different constructs in parental fibroblasts (open bars) and cadherin-transfected fibroblasts (filled bars). Promoter activities were normalized to account for differences in transfection efficiency. The activities of the different constructs are shown as percentages relative to that of the CMV promoter. n, number of independent transfections; asterisks, significant differences by the Student t test (P < 0.005). (C) Influence of β-catenin (β-cat), Xwnt-8, and Xwnt-5A on fibronectin promoter activity in cadherin-transfected fibroblasts. n, number of experiments; asterisks, significant differences by the Student t test (P < 0.005). The activity of the corresponding reporter gene construct was set to 100%. (D) Influence of LEF-1 and LEF-1 deletion mutants, lacking either the β-catenin binding site (LEF-1 ΔβBD) or the DNA binding site (LEF-1 ΔHMG), on the fibronectin promoter in parental fibroblasts. The activity of the reporter was set as 100%. The number of experiments is shown below each bar.