Nck at the centre of endothelial cell migration

Reorganisation of the cytoskeletal architecture underlies the morphological and functional changes that are involved in directional cell migration. Extracellular signals that alter tyrosine phosphorylation, e.g. the activation of receptor tyrosine kinases (RTKs), are recognised by proteins that contain a Src homology (SH) 2 domain, such as the Nck family of adaptors, which then promote remodelling of the actin cytoskeleton. Although it is well established that Nck is involved in cell motility and adhesion, its exact roles during directional cell migration and the underlying mechanisms are unresolved. Here, Gonzalo Rivera and co-workers (p. 1637) use a combination of genetics and quantitative live-cell imaging to elucidate the role of Nck in endothelial cell migration. Upon functional abrogation of Nck they observe that cell migration is deficient and its directionality is impaired, mainly owing to the loss of front-to-rear polarity. Furthermore, they find that, when compared with wild-type cells, loss of Nck results in a reduced force from fibronectin-mediated cell–matrix adhesions, as well as reduced levels of myosin phosphorylation and Rho activity, but increased activities of Rac1 and Cdc42. On the basis of these data, the authors conclude that Nck promotes the directional migration of endothelial cells by coordinating the stimulation of protrusions at the cell front, as well as by stabilising the cell front through promoting the maturation of cell–matrix adhesions.