Figure 5. TGF-β activates canonical Wnt signalling by decreasing Dkk-1.

(a) TGF-β induces nuclear accumulation of β-catenin in cultured human fibroblasts as shown by Western blot from cytoplasmic and nuclear extracts (n=4). (b) TGF-β stimulates the activity of a TCF/Lef reporter construct (n=8). (c) Adenoviral overexpression of TBRI^act in the skin of mice (Ad-TBRI) induced nuclear accumulation of β-catenin in fibroblasts as compared with control mice infected with adenovirus encoding for LacZ (Ad-LacZ) (n ≥ 6). (d) Ad-TBRI uprgeulated the mRNA levels of the Wnt target gene axin-2 (n ≥ 6). (e) Incubation with TGF-β reduced the mRNA levels of Dkk-1 in cultured fibroblasts (n=7). (f) TGF-β decreased the protein levels of Dkk-1 in cultured fibroblasts (n=5). (g) Decreased levels of Dkk-1 were also observed in the skin of Ad-TBRI mice by western blot (n=4). Representative bands and the mean results of the densiometric quantification are shown in a, f and g. * Indicates P-values of less than 0.05 as compared with unstimulated cells (a, b, e and f, as analysed with the Wilcoxon signed-rank test) and with Ad-LacZ mice (c, d and g, as analysed using the Mann–Whitney U-test). All data are expressed as mean ± s.e.m.