Wnt3a-regulated TCF4/β-catenin complex directly activates the key Hedgehog signalling genes and .

The Wnt and Hedgehog signalling pathways serve key roles in diverse developmental processes. However, the molecular associations between these two signalling pathways remains unclear. Previous transcriptome studies on human foreskin fibroblasts have indicated that Wnt signalling activation induces the expression of key Hedgehog signalling genes, including smoothened, frizzled class receptor () and GLI family zinc finger 1 (). Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) results revealed that Wnt3a treatment induced the expression of the key Hedgehog signalling genes, including , patched (), and . In addition, western blot analyses demonstrated that Wnt3a treatment resulted in the accumulation of cellular Smo and Gli proteins. Furthermore, promoter sequence analysis revealed that the putative β-catenin/T-cell factor (TCF)-4 complex binding motifs (//AAAG) were located within 1.5 kb of the and promoters. Results of the chromatin immunoprecipitation experiments and yeast-one hybrid assays revealed that TCF4 directly binds to the and promoters, with two binding sites for and a single binding site for . Further analysis showed that the β-catenin/TCF4 complex binds to the and promoters. To investigate the functions of TCF4 and β-catenin in transcriptional regulation of and and β- were transiently expressed in fibroblast cells. RT-qPCR results demonstrated that overexpression of and β- induced the expression of and . In addition, small interfering RNA-mediated suppression of β- resulted in the downregulation of and expression levels, even under Wnt3a treatment. Suppression of β- and expression inhibited cell proliferation. Taken together, the results of the present study suggested that the β-catenin/TCF4 complex directly activates and by binding to their promoters, which in turn controls cell proliferation in human fibroblasts.