Abstract
Adherens junctions (AJs) fundamentally mediate cell-cell adhesion, yet the mechanisms that determine where or when AJs assemble are not understood. Here we reveal a mechanosensitive clutch that initiates AJ assembly. Before cell-cell contact, α-catenin couples surface E-cadherin complexes to retrograde flow of the actin cortex. Cortical flows with opposed orientations persist after contact, applying tension to α-catenin within trans-ligated cadherin complexes. Tension unfolds the α-catenin actin-binding domain (ABD), which is expected to mediate a catch bond with F-actin. However, catch bond behaviour is not sufficient for AJ assembly in a molecular clutch model. Instead, it is also necessary for the activated ABD to promote cis-clustering of E-cadherin molecules by bundling F-actin. Thus, this α-catenin clutch transduces the mechanical signal of cortical flow to assemble AJs.
Competing Interest Statement
The authors have declared no competing interest.