Roles and interactions of Enabled, Diaphanous and Capping Protein in regulation of actin structures in Drosophila development

Proper regulation of the actin cytoskeleton is integral for development. As a dynamic polymer, actin is highly regulated by a host of binding proteins, which alter the geometry of the polymer network. Specific actin geometries are associated with migration, protrusive behavior, and cell shape changes. Individual cell shape changes are coupled via cell - cell adhesion to affect both wound healing and morphogenesis -- the dynamic tissue rearrangements associated with development. Improper actin regulation is associated with cancer and disease. Here we use Drosophila oogenesis and embryonic morphogenesis as models for in vivo actin regulation to explore: (1) How the balance between filament elongation and filament capping affects development, finding that the antagonistic relationship between the filament elongator, Enabled, and the filament capper, Capping Protein, is integral for proper oogenesis. (2) How filament elongation factors interact and modulate actin dynamics biochemically, in cell culture and in vivo. Here we found Enabled and another elongation factor, Diaphanous, directly interact, resulting in negative regulation of Diaphanous' effect on actin polymerization. (3) Finally I expand on how the relationship between elongation factors works in vivo, finding that each elongation factor plays a dominant role in separate tissues in filopodium formation during a dynamic morphogenetic event.Doctor of Philosoph