We have found that epithelial cells engage in a process of cadherin- mediated intercellular adhesion that utilizes calcium and actin polymerization in unexpected ways. Calcium stimulates filopodia, which penetrate and embed into neighboring cells. E-cadherin complexes cluster at filopodia tips, generating a two-rowed zipper of embedded puncta. Opposing cell surfaces are clamped by desmosomes, while vinculin, zyxin, VASP, and Mena are recruited to adhesion zippers by a mechanism that requires α- catenin. Actin reorganizes and polymerizes to merge puncta into a single row and seal cell borders. In keratinocytes either null for α-catenin or blocked in VASP/Mena function, filopodia embed, but actin reorganization/polymerization is prevented, and membranes cannot seal. Taken together, a dynamic mechanism for intercellular adhesion is unveiled involving calcium-activated filopodia penetration and VASP/Mena-dependent actin reorganization/polymerization.
Vasioukhin, V., Bauer, C., Yin, M., & Fuchs, E. (2000). Directed actin polymerization is the driving force for epithelial cell- cell adhesion. Cell, 100(2), 209–219. https://doi.org/10.1016/S0092-8674(00)81559-7