Actin 'purse string' filaments are anchored by E-cadherin-mediated adherens junctions at the leading edge of the epithelial wound, providing coordinated cell movement

At the leading edge of healing embryonic epithelium, cables of actin filame nts appear to extend from cell to cell, forming a ring around the wound cir cumference. It has been hypothesized that this actin filament cable functio ns as a contractile 'purse string' to facilitate wound closure. We have obs erved this cable in large, circular healing epithelial wounds in corneas of adult mice. To elucidate the role of the actin filament cable, we characte rized the molecular components associated with the cell-cell junction where the actin filament cable inserts and with the actin filament cable itself, and we studied the effect of disruption of the cable using an E-cadherin f unction-blocking antibody, ECCD-1. Localization of E-cadherin and the direc t association of catenins with actin filament cable at the cell-cell interf ace of the actin cable confirmed that the cell-cell junction associated wit h the actin filament cable is an adherens junction. The E-cadherin function -blocking antibody caused disruption of the actin filament cable and induct ion of prominent lamellipodial extensions on cells at the leading edge, lea ding to a ragged uneven epithelial wound margin. These data demonstrate tha t cell-to-cell associated E-cadherin molecules link the actin filament cabl e, forming a functional adherens junction, and that the actin filament cabl e plays a role in coordinating cell movement.