PROJECT SUMMARY/ABSTRACT Most cells of the body experience physiological and environmental stresses during their normal daily functions that can lead to a ruptured cell cortex (plasma membrane and underlying cortical cytoskeleton). The capacity of cells to rapidly repair general daily injuries, as well as ones resulting from trauma, infection, or diseases/cancer, is essential for their survival. The general aim of this proposal is to delineate how cells deal with such cell cortex disruptions to efficiently and effectively repair the lesions. We have developed a robust inducible single cell repair model using the syncytial Drosophila embryo that has superb amenability for live imaging and genetic tractability that is unavailable in other cell wound repair models. Our repair model has allowed us to successfully employ global genetic approaches for the first time to delineate the outline of cellular events and to identify many required genes/gene families providing clear molecular entry points for investigating specific key steps in the repair process. Our long-term goal is to establish the molecular framework underpinning cell wound repair. The specific aims of this proposal are 1) to determine the means by which the membrane plug re-seals the torn plasma membrane then facilitates wound closure; 2) to determine how the actin ring is attached to the overlying plasma membrane to coordinate their actions as the wound is pulled closed; and 3) to elucidate the basis of cell cortex remodeling following wound closure. Our findings will impact our understanding of cell wound repair across phyla, complement work done in other cell repair models, provide new insights into key players/events needed for efficient repair, as well as how they work in concert to achieve successful wound closure, and contribute to our understanding of related fundamental cellular and developmental events. Our studies are also expected to be of significant medical relevance, as understanding the molecules, machineries, and pathways governing cell wound repair will be extremely valuable for developing new or enhancing existing strategies for treating cellular damage, and for disciplines such as regenerative medicine where cell based constructs are used to reconstruct tissues or clinical drug delivery systems where molecules cross cell membranes.