Actin/Myosin-V- and Activity-Dependent Inter-synaptic Vesicle Exchange in Central Neurons

Abstract

Summary: Vesicle sharing between synaptic boutons is an important component of the recycling process that synapses employ to maintain vesicle pools. However, the mechanisms supporting and regulating vesicle transport during the inter-synaptic exchange remain poorly understood. Using nanometer-resolution tracking of individual synaptic vesicles and advanced computational algorithms, we find that long-distance axonal transport of synaptic vesicles between hippocampal boutons is partially mediated by the actin network, with myosin V as the primary actin-dependent motor that drives this vesicle transport. Furthermore, we find that vesicle exit from the synapse to the axon and long-distance vesicle transport are both rapidly and dynamically regulated by activity. We corroborated these findings with two complementary modeling approaches of vesicle exit, which closely reproduced experimental observations. These findings uncover the roles of actin and myosin V in supporting the inter-synaptic vesicle exchange and reveal that this process is dynamically modulated in an activity-dependent manner. : Gramlich and Klyachko uncover the roles of actin and myosin V in supporting vesicle transport during inter-synaptic exchange (ISVE). They also reveal that this process is rapidly and dynamically modulated in an activity-dependent manner. Keywords: inter-synaptic vesicle exchange, synaptic vesicle, vesicle recycling, axonal transport, myosin V, actin cytoskeleton, single-particle tracking