New collaborations of formins in actin assembly and organization

Cellsrapidly remodel their actin cytoskeletons in order to performa variety of essential functionsincluding directed cell migration, cell morphogenesis, cytokinesis, phagocytosis, neuronal path finding, and synapse formation. Precise regulation of actin filament assembly dynamics during these processes is critical,and defects in the machinery performing these functionslead todiseases, including birth defects, mental retardation,heart disease, and invasive cancers. An emerging view is that multiple actin assembly-promoting factors work in concert to control actin filament dynamics in cells, but the underlying mechanisms of such collaborative actin assemblyhave remained a mystery until now. In my talk, I will present new mechanistic findings that describe two key collaborations involving formins (a family of conserved actin assembly-promotingfactors) and their in vivo binding partners. This will include novel insights gained by multi-color TIRF imaging at the single molecule level and reconstitution of actin filament assembly/bundlingin vitro.These observationsreveal that certain formins, apart fromtheir more established roles in actin nucleation and elongation,promote filament bundling in vivo, and are critical for the formation offilopodialprotrusions in multiple cell types.My talk will conclude with a discussion ofwhere my research is heading in the coming 5-10 years and how I will apply a multi-disciplinary approach toaddress several fundamental yet unanswered questions in the field.