"Force Generation and Actomyosin Dynamics during Embryonic Wound Repair"

Epithelial tissues are protective barriers that display a remarkable ability to repair wounds. Wound repair is often associated with an accumulation of actin and non-muscle myosin II around the wound, forming a purse string. However, the role of actomyosin networks in generating mechanical force during wound repair is not well understood. We are investigating the mechanisms of force generation during wound repair in the epidermis of early and late Drosophila embryos. We find that wound closure is faster in early embryos where actomyosin networks at the medial cortex of the wounded cells also contribute to rapid wound repair. Laser ablation demonstrates that both medial and purse string actomyosin networks generate contractile force. Quantitative analysis of protein localization dynamics during wound closure indicates that the rapid contraction of medial actomyosin structures during wound repair in early embryos involves the disassembly of the actomyosin network. By contrast, actomyosin purse strings in late embryos contract more slowly in a mechanism that involves network condensation. We propose that the combined action of two force-generating structures, a medial actomyosin network and an actomyosin purse string, contributes to the increased efficiency of wound repair in the early embryo.