W hen it comes to cadherin regulation, it is not all about α- and β-catenins. Drosophila epithelial cadherin requires a novel regulatory region for cell migration in developing ovaries, according to Pacquelet and Rørth (page 803).

Cadherins are used in cell–cell adhesion and migration in a variety of tissues. The cytoplasmic tail of cadherin contacts the actin cytoskeleton through α- and β-catenin. Studies in tissue culture cells suggested that modulating the interaction between cadherin and the catenins would alter the adhesion strength of cadherin and facilitate migration.

To test whether such mechanisms work in vivo, the authors fused the full-length cadherin or just its transmembrane domain to α- or β-catenin. The full-length cadherin–α-catenin fusion rescued cell–cell interactions and migration in tissues lacking wild-type DE-cadherin or β-catenin. Thus no modulation is required between DE-cadherin and α-catenin for normal migration. If the link between DE-cadherin and the actin cytoskeleton needs to be tempered in vivo, the tempering must happen downstream of α-catenin.

Removing the cytoplasmic tail of cadherin in the α-catenin fusion protein blocked migration in the ovary, though adhesion was normal. Although the specific mechanisms are not yet known, the authors think that this cadherin cytoplasmic domain is required to maximize adhesion force during migration.