Genome-wide analysis of canonical Wnt target gene regulation in Xenopus tropicalis challenges β-catenin paradigm.

Wnt/β-catenin signaling is an important cell-to-cell signaling mechanism that controls gene expression during embryonic development and is critically implicated in human diseases. Developmental, cellular, and transcriptional responses to Wnt signaling are remarkably context-specific in different biological processes. While nuclear localization of β-catenin is the key to activation of the Wnt/β-catenin pathway and target gene expression, the molecular mechanisms of how the same Wnt/β-catenin signaling pathway induces specific responses remain undetermined. Recent advances in high-throughput sequencing technologies and the availability of genome information for Xenopus tropicalis have enabled us to uncover a genome-wide view of Wnt/β-catenin signaling in early vertebrate embryos, which challenges previous concepts about molecular mechanisms of Wnt target gene regulation. In this review, we summarize our experimental approaches, introduce the technologies we employed and focus on recent findings about Wnt target gene regulation from Xenopus research. We will also discuss potential functions of widespread β-catenin binding in the genome that we discovered in this species.