Myosin VI and vinculin cooperate during the morphogenesis of cadherin cell–cell contacts in mammalian epithelial cells

Abstract

Cooperation between cadherins and the actin cytoskeleton controls many aspects of epithelial biogenesis. We report here that myosin VI critically regulates the morphogenesis of epithelial cell–cell contacts. As epithelial monolayers mature in culture, discontinuous cell–cell contacts are initially replaced by continuous (cohesive) contacts. Myosin VI is recruited to cell contacts as they become linear and cohesive, where it forms a biochemical complex with epithelial cadherin (E-cadherin). Myosin VI is necessary for strong cadherin adhesion, for cells to form cohesive linear contacts, and for the integrity of the apical junctional complex. We find that vinculin mediates this effect of myosin VI. Myosin VI is necessary for vinculin and E-cadherin to interact. A combination of gain and loss of function approaches identifies vinculin as a downstream effector of myosin VI that is necessary for the integrity of intercellular contacts. We propose that myosin VI and vinculin form a molecular apparatus that generates cohesive cell–cell contacts in cultured mammalian epithelia.

Cell adhesion receptors in mechanotransduction

“…Myosin VI has also been implicated in the late stage of junction maturation [29]*. This myosin is a minus end directed motor previous implicated in vesicular transport.…”

Spatial integration of E-cadherin adhesion, signalling and the epithelial cytoskeleton

“…In different epithelia, inhibition of ROCK [13,15,78] or depletion of myosin VI [42] or tropomyosin5 [79] (a filament side-binding protein) results in the appearance of curved, rather than linear junctions. Without tropomyosin5, junctions are floppier, with reduced recoil upon laser ablation, suggesting that stable thin bundles are required to generate taught, straight junctions [79].…”

“…At junctions, filaminA and filaminB are known to fine tune activation of RhoA and Rac1 via binding to the GEF Trio or the GAP FilGAP, respectively [38,41]. Furthermore, F-actin bundles may be stabilised by a number of different myosins that co-localise with cadherins and are functionally important for junction maintenance [15,42,43]. Yet, in some epithelia, contractile markers such as phosphorylated Myosin Light Chain (pMLC) are not highly enriched at junctional actin, particularly when peripheral thin bundles are clearly separable (Fig.1d).…”

Bacillus cereus Certhrax ADP-ribosylates Vinculin to Disrupt Focal Adhesion Complexes and Cell Adhesion

“…These phenotypes can be linked to the prominent role vinculin plays in organizing focal adhesion complexes, linking the ECM to the actin cytoskeleton. This connection allows non-motile epithelial cells to remain adherent to the ECM and form a coherent physical barrier (32)(33)(34) and also allows motile cells, like macrophages, to form protrusions allowing for directed movement (35)(36)(37). Vinculin signals through direct interactions with the actin cytoskeleton and focal adhesion proteins like talin, as well as through recruitment of other proteins responsible for maintaining cytoskeletal cohesion.…”