期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2015
卷号：112
期号：15
页码：4779-4784
DOI：10.1073/pnas.1424597112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceCompared with vesicle exocytosis and endocytosis, relatively little is known about vesicle recycling. Here, we developed a novel methodological approach, potentially applicable to all axosomatic synapses, to quantify the kinetics of vesicle recycling with exquisite signal and temporal resolution. Using this approach combined with electron-microscopic observations, we estimated that [~]80% of synaptic vesicles participate in recycling and provided an explanation to reconcile the discrepancies in previous reports. We kinetically dissected vesicle recycling in the calyceal terminal, defined a new concept of the readily priming pool, and proposed a realistic kinetic model to quantify the basic properties of vesicle recycling. These findings contribute to filling the gap in understanding vesicle recycling, particularly postendocytotic vesicle trafficking. Vesicle recycling is pivotal for maintaining reliable synaptic signaling, but its basic properties remain poorly understood. Here, we developed an approach to quantitatively analyze the kinetics of vesicle recycling with exquisite signal and temporal resolution at the calyx of Held synapse. The combination of this electrophysiological approach with electron microscopy revealed that [~]80% of vesicles ([~]270,000 out of [~]330,000) in the nerve terminal are involved in recycling. Under sustained stimulation, recycled vesicles start to be reused in tens of seconds when [~]47% of the preserved vesicles in the recycling pool (RP) are depleted. The heterogeneity of vesicle recycling as well as two kinetic components of RP depletion revealed the existence of a replenishable pool of vesicles before the priming stage and led to a realistic kinetic model that assesses the size of the subpools of the RP. Thus, our study quantified the kinetics of vesicle recycling and kinetically dissected the whole vesicle pool in the calyceal terminal into the readily releasable pool ([~]0.6%), the readily priming pool ([~]46%), the premature pool ([~]33%), and the resting pool ([~]20%).
关键词：kinetics ; vesicle recycling ; vesicle pool ; calyx of Held ; short-term plasticity
