School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK.
Neuron. 2012 Nov 8;76(3):579-89. doi: 10.1016/j.neuron.2012.08.042.
At small central synapses, efficient turnover of vesicles is crucial for stimulus-driven transmission, but how the structure of this recycling pool relates to its functional role remains unclear. Here we characterize the organizational principles of functional vesicles at native hippocampal synapses with nanoscale resolution using fluorescent dye labeling and electron microscopy. We show that the recycling pool broadly scales with the magnitude of the total vesicle pool, but its average size is small (∼45 vesicles), highly variable, and regulated by CDK5/calcineurin activity. Spatial analysis demonstrates that recycling vesicles are preferentially arranged near the active zone and this segregation is abolished by actin stabilization, slowing the rate of activity-driven exocytosis. Our approach reveals a similarly biased recycling pool distribution at synapses in visual cortex activated by sensory stimulation in vivo. We suggest that in small native central synapses, efficient release of a limited pool of vesicles relies on their favored spatial positioning within the terminal.
在小的中枢突触中，囊泡的有效周转对于刺激驱动的传递至关重要，但这个回收池的结构与其功能角色如何相关仍不清楚。在这里，我们使用荧光染料标记和电子显微镜以纳米级分辨率来描述原生海马突触中功能性囊泡的组织原则。我们表明，回收池与总囊泡池的大小大致成比例，但平均大小较小（~45 个囊泡）、高度可变，并且受 CDK5/钙调神经磷酸酶活性的调节。空间分析表明，回收囊泡优先排列在活性区附近，而这种隔离在肌动蛋白稳定时被破坏，从而减缓了活性驱动的胞吐作用的速率。我们的方法揭示了在体内通过感觉刺激激活的视觉皮层中的突触中也存在类似的偏向性回收池分布。我们认为，在小的原生中枢突触中，有限数量的囊泡的有效释放依赖于它们在末梢内的优先空间定位。
