Roles of Wnt pathway genes wls, wnt9a, wnt5b, frzb and gpc4 in regulating convergent-extension during palate morphogenesis

Wnt signaling is a critical pathway for tissue morphogenesis participating in cellular behavior changes, notably during the convergent-extension process. Interactions between Wnt secreting and receiving cells during convergenceextension remain elusive. We investigated the role and genetic interactions of Wnt ligands and their trafficking factors, Wls, Gpc4 and Frzb in the context of palate morphogenesis. We described that the chaperon Wls and its ligands Wnt9a and Wnt5b are expressed in the ectoderm, whereas juxtaposed chondrocytes express Frzb and Gpc4. Using wls, gpc4, frzb, wnt9a and wnt5b mutants, we genetically dissected Wnt signal operating between secreting ectoderm and receiving chondrocytes. Our analysis delineates that noncanonical Wnt signaling is required for cell intercalation, and that wnt5b and wnt9a are required for palate extension, in the antero-posterior and transverse