alpha-Catenin phosphorylation promotes intercellular adhesion through a dual-kinase mechanism

摘要

The cadherin-catenin adhesion complex is a key contributor to epithelial tissue stability and dynamic cell movements during development and tissue renewal. How this complex is regulated to accomplish these functions is not fully understood. We identified several phosphorylation sites in mammalian alpha E-catenin (also known as catenin alpha-1) and Drosophila alpha-Catenin within a flexible linker located between the middle (M)-region and the carboxy-terminal actin-binding domain. We show that this phospho-linker (P-linker) is the main phosphorylated region of alpha-catenin in cells and is sequentially modified at casein kinase 2 and 1 consensus sites. In Drosophila, the P-linker is required for normal alpha-catenin function during development and collective cell migration, although no obvious defects were found in cadherin-catenin complex assembly or adherens junction formation. In mammalian cells, non-phosphorylatable forms of alpha-catenin showed defects in intercellular adhesion using a mechanical dispersion assay. Epithelial sheets expressing phosphomimetic forms of alpha-catenin showed faster and more coordinated migrations after scratch wounding. These findings suggest that phosphorylation and dephosphorylation of the alpha-catenin P-linker are required for normal cadherin-catenin complex function in Drosophila and mammalian cells.