Requirement for Pak3 in Rac1-induced organization of actin and myosin during Drosophila larval wound healing.

Rho-family small GTPases regulate epithelial cell sheet migration by organizing actin and myosin during wound healing. Here, we report that Pak3, but not Pak1, is a downstream target protein for Rac1 in wound closure of the Drosophila larval epidermis. Pak3-deficient larvae failed to close a wound hole and this defect was not rescued by Pak1 expression, indicating differential functions of the two proteins. Pak3 localized to the wound margin, which selectively required Rac1. Pak3-deficient larvae showed severe defects in actin-myosin organization at the wound margin and in submarginal cells, which was reminiscent of the phenotypes of Rac1-deficient larvae. These results suggest that Pak3 specifically mediates Rac1 signaling in organizing actin and myosin during Drosophila epidermal wound healing. Copyright Â