αE-catenin regulates actin dynamics independently of cadherin-mediated cell–cell adhesion

alphaE-catenin binds the cell-cell adhesion complex of E-cadherin and beta-catenin (beta-cat) and regulates filamentous actin (F-actin) dynamics. In vitro, binding of alphaE-catenin to the E-cadherin-beta-cat complex lowers alphaE-catenin affinity for F-actin, and alphaE-catenin alone can bind F-actin and inhibit Arp2/3 complex-mediated actin polymerization. In cells, to test whether alphaE-catenin regulates actin dynamics independently of the cadherin complex, the cytosolic alphaE-catenin pool was sequestered to mitochondria without affecting overall levels of alphaE-catenin or the cadherin-catenin complex. Sequestering cytosolic alphaE-catenin to mitochondria alters lamellipodia architecture and increases membrane dynamics and cell migration without affecting cell-cell adhesion. In contrast, sequestration of cytosolic alphaE-catenin to the plasma membrane reduces membrane dynamics. These results demonstrate that the cytosolic pool of alphaE-catenin regulates actin dynamics independently of cell-cell adhesion.