Direct cadherin-activated cell signaling: a view from the plasma membrane

Abstract

Classical cadherin adhesion molecules are key determinants of cell recognition and tissue morphogenesis, with diverse effects on cell behavior. Recent developments indicate that classical cadherins are adhesion-activated signaling receptors. In particular, early-immediate Rac signaling is emerging as a mechanism to coordinate cadherin-actin integration at the plasma membrane.

Figure 1.

A model for cadherin-activated Rac signaling participation in early cell–cell recognition. (A) Productive cadherin ligation in newly forming contacts (1) activates Rac signaling at the plasma membrane via a PI3 kinase–dependent intermediary step (2) and possibly also a pathway independent of PI3 kinase (3). One key consequence of Rac activation is the stimulation of cadherin-directed actin assembly by Arp2/3 (4), thereby leading to protrusion of the cell surface (5). (B) Cadherin-directed actin assembly, coordinated by Rac activation, is predicted to direct the surface-protrusive activity of the actin cytoskeleton toward such nascent contacts, to extend the regions of contact and ultimately stabilize cell–cell adhesion.