Intestinal Development: The Many Faces of Wnt Signaling

The canonical Wnt pathway and signaling through β-catenin. In the absence of Wnt ligand, β-catenin is phosphorylated by glycogen synthase kinase-3 (GSK3) and targeted for degradation through destruction complexes containing APC, Axin, and other proteins (left). As a result, Wnt target genes remain repressed. During active signaling, Wnt proteins bind to their receptors and inhibit phosphorylation of β-catenin by GSK3, thus preventing its degradation in APC complexes (right). As a result, stabilized β-catenin is redistributed from the cell membrane to the nucleus, where it interacts with TCF family transcription factors as a co-activator to activate target gene transcription. β-cat, β-catenin; APC, adenomatous polyposis coli; DVL, disheveled.