The regulation of junctional actin dynamics by cell adhesion receptors

The formation of cell-cell junctions and the development of stable cell-cell adhesion require the association of actin filaments with the sites of cell-cell adhesion. From the initial formation of cell-cell junctions, which appear as punctate, spot-like junctions, to the formation of a stable actin belt that runs adjacent to cell-cell junctions, the actin cytoskeleton is closely associated with the adhesion apparatus. Importantly, the junctional actin is highly dynamic, even after the maturation of intercellular junctions and the development of apico-basal polarity. Regulators of both branched actin networks and of linear actin cables have been identified at cell-cell junctions, in particular at adherens junctions but also at tight junctions. These regulators of actin dynamics are often directly or indirectly associated with cell adhesion receptors, suggesting a critical role for cell adhesion molecules for the recruitment of regulators of actin dynamics to cell-cell junctions. Here, we review the recent developments on the role of cell adhesion molecules at epithelial and endothelial cell-cell junctions in the regulation of junctional actin dynamics.