Fig. 1.

Proposed model for action of Wnt signaling on GLP-1 or GIP production. Wnt ligands bind to Frizzled (Fz) receptors and low-density lipoprotein receptor-related protein (LRP) 5/6 coreceptors, whereby dishevelled (Dsh) is recruited to the membrane and GSK3β is inhibited by the activation of Dsh by Fz. This leads to the translocation of β-catenin into the nucleus, where it binds with TCF to activate specific target genes such as GLP-1 and GIP in intestinal L-cells or K-cells. GLP-1, glucagon-like peptide-1; GIP, glucose-dependent insulinotropic polypeptide.