Afadin regulates actomyosin organization through αE-catenin at adherens junctions

Actomyosin-undercoated adherens junctions are critical for epithelial cell integrity and remodeling. Actomyosin associates with adherens junctions through alphaE-catenin complexed with beta-catenin and E-cadherin in vivo; however, in vitro biochemical studies in solution showed that alphaE-catenin complexed with beta-catenin binds to F-actin less efficiently than alphaE-catenin that is not complexed with beta-catenin. Although a "catch-bond model" partly explains this inconsistency, the mechanism for this inconsistency between the in vivo and in vitro results remains elusive. We herein demonstrate that afadin binds to alphaE-catenin complexed with beta-catenin and enhances its F-actin-binding activity in a novel mechanism, eventually inducing the proper actomyosin organization through alphaE-catenin complexed with beta-catenin and E-cadherin at adherens junctions.