The Casein Kinase I Family: Roles in Morphogenesis

Abstract Wnt signals play important roles in development and oncogenesis and are transduced through at least two pathways: a canonical β-catenin-dependent and a β-catenin-independent cascade. Casein kinase I (CKI) is required in both invertebrates and vertebrates to transduce canonical Wnt signals. However, its role in the β-catenin-independent pathway was unknown. During vertebrate embryogenesis, the β-catenin-independent cascade is thought to control cell movements and has been postulated to be analogous to the Drosophila planar cell polarity pathway, which signals through the JNK cascade. Here, we report that blocking CKI function inhibits embryonic morphogenesis and activates JNK in cell lines. These studies suggest that CKI might also act in the β-catenin-independent pathway and indicate a role for CKI during convergence extension in early vertebrate development.