Kaiso is a bimodal modulator for Wnt/beta-catenin signaling.

The Wnt family of secreted ligands plays critical roles during embryonic development and tumorigenesis. Here we show that Kaiso, a dual specific DNA-binding protein, functions as a bimodal regulator of canonical Wnt signaling. Loss-of-function analysis of Kaiso abrogated Wnt-mediated reporter activity and axis duplication, whereas gain-of-function analysis of Kaiso dose-dependently resulted in synergistic and suppressive effects. Our analyses further suggest Kaiso can regulate TCF/LEF1-activity for these effects via modulating HDAC1 and beta-catenin-complex formation. Our studies together provide insights into why Kaiso null mice display resistance to intestinal tumors when crossed onto an Apc(Min/+) background.