Deciphering Neurofilament Motility in live cells

Neurofilaments are the most abundant cytoskeletal elements of mature neuronal axons. They are assembled in the axon and responsible for regulating the axon's diameter. These filaments are transported in a characteristic stop-and-go fashion along microtubule tracks toward the nerve terminal driven by the motor proteins, kinesin and dynein.~ To explore the mechanisms underlying the observed stop-and-go transport, we devise a computational model~in which kinesin and dynein---coupled by respective force generation (tug-of-war)--- are attached to the neurofilament cargo.~ The resulting movement and kinetic characteristics are compared with highly time-resolved kymograph recordings.~ This comparison determines whether the observed kinetics are consistent with a tug-of-war model, and also renders an estimate of how many motors are attached to the cargo during transport.