Context-dependent regulation of the &bgr;-catenin transcriptional complex supports diverse functions of Wnt/&bgr;-catenin signaling

Wnt/&bgr;-catenin signaling is activated repeatedly during an animal’s lifespan, and it controls gene expression through its essential nuclear effector, &bgr;-catenin, to regulate embryogenesis, organogenesis, and adult homeostasis. Although the &bgr;-catenin transcriptional complex has the ability to induce the expression of many genes to exert its diverse roles, it chooses and transactivates a specific gene set from among its numerous target genes depending on the context. For example, the &bgr;-catenin transcriptional complex stimulates the expression of cell cycle-related genes and consequent cell proliferation in neural progenitor cells, while it promotes the expression of neural differentiation-related genes in differentiating neurons. Recent studies using animal and cell culture models have gradually improved our understanding of the molecular basis underlying such context-dependent actions of the &bgr;-catenin transcriptional complex. Here, we describe eight mechanisms that support &bgr;-catenin-mediated context-dependent gene regulation, and their spatio-temporal regulation during vertebrate development. In addition, we discuss their contribution to the diverse functions of Wnt/&bgr;-catenin signaling.