p53 binding in mouse embryonic stem cells untreated or treated with adriamycin

Both p53 and the Wnt signaling pathways play important roles in tumorigenesis and development. However, few studies, particularly on a genome-wide scale, have linked these two pathways. Here we show that p53 directly regulates the Wnt signaling pathway in murine embryonic stem cells (mESCs) using an integrated genome-wide approach. A chromatin-immunoprecipitation-based microarray assay (ChIP-chip) reveals that the Wnt signaling pathway is significantly over-represented in p53 bound genes. Using gene expression microarray and real-time PCR, we demonstrate that the expressions of many Wnts are robustly induced by various stresses, including DNA damage and hypoxia that activate p53. Importantly, the activation of p53 is a prerequisite for the induction of Wnts. Moreover, conditional medium (CM) collected from ultraviolet (UV)-treated mESCs contains an anti-differentiation activity, which can be lowered by either the addition of Wnt signaling inhibitors into the CM or the reduction of p53 levels in UV-treated mESCs. These results suggest that stressed mESCs utilize the p53-Wnt signaling axis to signal neighboring mESCs to delay the differentiation. Together, our results uncover a novel connection between p53 and the Wnt signaling pathways in mediating cell-to-cell communication in mESCs, and provide insights into the functions of these two pathways in tumorigenesis and development ChIP-chip assay was done per Agilent’s ChIP-chip protocol (Version 10.0). The goal of this experiment is to identify the p53 binding sites in cells untreated or treated with adriamycin (DNA damage).