Kaiso/p120-catenin and TCF/β-catenin complexes coordinately regulate canonical Wnt gene targets

beta-catenin-dependent or canonical Writ signals are fundamental in animal development and tumor progression. Using Xenopus laevis, we report that the BTB/POZ zinc finger family member Kalso directly represses canonical Writ gene targets (Siamois, c-Fos, Cyclin-D1, and c-Myc) in conjunction with TCF/LEF (TCF). Analogous to P-catenin relief of TCF repressive activity, we show that p120-catenin relieves Kaiso-mediated repression of Siamois. Furthermore, Kalso and TCF coassociate, and combined Kaiso and TCF derepression results in pronounced Siamois expression and increased beta-catenin coprecipitation with the Siamois promoter. The functional interdependency is underlined by Kalso suppression of P-catenin-induced axis duplication and by TCF-3 rescue of Kalso depletion phenotypes. These studies point to convergence of parallel p120-catenin/Kaiso and beta-catenin/TCF signaling pathways to regulate gene expression in vertebrate development and possibly carcinogenesis.