TGF-β signaling regulates DACT1 expression in intestinal epithelial cells.

DACT1, was first identified as a Dishevelled-associated antagonist of Wnt signaling pathway. It has been reported that DACT1 functions in embryonic development and tumorigenesis. However, the regulation of DACT1 still remains unclear. We found Wnt signaling has no effect on DACT1, but TGF-beta increases expression of DACT1 in intestinal epithelial cells. In addition, the minimal promoter is located in the region of -500 bp to +1 bp and the region between -3000 bp to +1 bp enhanced promoter activity. Site-directed mutation analysis was performed and indicated that potential regulatory elements was near -335 bp. Our study provided the basic information for the exploration of DACT1 regulation and expression. Moreover, TGF-beta inhibits Wnt signaling to enhance the function of DACT1 inhibiting Wnt signaling.