Protrusion growth driven by myosin-generated force

Abstract

Actin-based protrusions are found on the surface of all eukaryotic cells, where they support diverse biological activities essential for life. Models of protrusion growth hypothesize that actin filament assembly provides the mechanical force for bending the plasma membrane outward. However, membrane-associated myosin motors are also abundant in protrusions, though their potential for contributing growth-promoting force remains unexplored. Using a novel inducible system that docks myosin motor domains to membrane binding modules with temporal control, we found that the application of myosin-generated force to the plasma membrane is sufficient for driving robust elongation of protrusions. Protrusion growth scaled with motor accumulation, required active, barbed end-directed force, and was independent of cargo delivery or the recruitment of canonical barbed end elongation factors. Application of growth-promoting force was also supported by structurally distinct myosin motor domains and membrane binding modules. We conclude that myosin-generated force can drive protrusion growth and this mechanism is likely active in diverse biological contexts.