Regulation of Canonical Wnt Signaling During Development and Diseases

Since the discovery of first Wnt gene (Wnt-1) in 1982, numerous investigations have focused on the roles of different Wnt proteins in regulation of cellular proliferation, differentiation and apoptosis in a cell-specific and contextual manner (Rao & Kuhl, 2011). Wnts mainly activate intracellular biological processes through one canonical pathway and two wellcharacterized non-canonical pathways including Wnt/PCP (planar cell polarity) and Wnt/Ca2+. The canonical pathway is also known as Wnt/┚-catenin pathway due to the key roles of ┚-catenin in transcriptional regulation of downstream genes. These pathways play distinct roles in embryonic development, cell fate determination, cell polarity generation and cell movements, cross-talks always occur through a variety of intracellular signal molecules. In this chapter, we mainly focus on the up-to-date understanding of canonical Wnt signaling, including its functions and regulatory mechanisms both in animal development and human diseases.