Sustained ?-catenin Activation at E-cadherin Junctions in the Absence of Mechanical Force.

ABSTRACT: Mechanotransduction at E-cadherin junctions has been postulated to be mediated in part by a force-dependent conformational activation of ?-catenin. Activation of ?-catenin allows it to interact with vinculin in addition to F-actin, resulting in a strengthening of junctions. Here, using E-cadherin adhesions reconstituted on synthetic, nanopatterned membranes, we show that activation of ?-catenin is dependent on E-cadherin clustering, and is sustained in the absence of mechanical force or association with F-actin or vinculin. Adhesions were formed by filopodia-mediated nucleation and micron-scale assembly of E-cadherin clusters, which could be distinguished as either peripheral or central assemblies depending on their relative location at the cell-bilayer adhesion. Whereas F-actin, vinculin, and phosphorylated myosin light chain associated only with the peripheral assemblies, activated ?-catenin was present in both peripheral and central assemblies, and persisted in the central assemblies in the absence of actomyosin tension. Impeding filopodia-mediated nucleation and micron-scale assembly of E-cadherin adhesion complexes by confining the movement of bilayer-bound E-cadherin on nanopatterned substrates reduced the levels of activated ?-catenin. Taken together, these results indicate that although the initial activation of ?-catenin requires micron-scale clustering that may allow the development of mechanical forces, sustained force is not required for maintaining ?-catenin in the active state.

SUBMITTER: Biswas KH 

PROVIDER: S-EPMC5018127 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature