Myosin V in the brain: Mutations lead to neurological defects

Ataxia may have multiple causes but one established molecular basis of this disease is a mutation in myosin V. Recent studies reviewed here have demonstrated that this protein is primarily found in neurons and functions as an organelle motor. Two of the organelles identified as cargo for this motor are ER vesicles and synaptic vesicles. Mutant rats and mice have been used to show that ER is missing from the dendritic spines when myosin V is defective. Collectively, these recent studies strongly argue for myosin V's role as an important organelle motor in neurons. Although there may be other functions of this motor such as RNA transport, organelle transport appears to be a major function. It will be important to look for modulations in myosin V's function during the recalibration of the central nervous system in microgravity. Changes in the activity of this motor could account for some of the locomotor disturbance and ataxia that are observed in astronauts following space flight.