Machinery of vesicle recycling functions beyond a vesicle supplier
報告人簡介
孫堅原，中國科學院深圳先進技術研究院腦所研究員，中國科學院大學崗位教授，國際雜志《synapse》和《Membrane Traffic》編委。從事突觸傳遞和神經信息處理的研究，聚焦神經遞質量子化釋放的機制和短時程突觸可塑性。
內容簡介
The recycling vesicle pool, with proper kinetics, ensures sustained synaptic transmission. However, the kinetic structure of recycling vesicle pool has never been quantitatively analyzed before, and most studies were performed at room temperature and under resting conditions. With the combination of presynaptic capacitance measurement and postsynaptic EPSC recording on calyx of Held synapses at physiological temperature, we studied vesicle recycling under sustained presynaptic stimulation. The kinetics of vesicle reuse was revealed by impeding transmitter refilling with folimycin. We found that more than 90% of vesicles in nerve terminals are involved in recycling but they were not homogeneously competent for immediate reuse. A significant surface pool of vesicles, assayed as an increased capacitance, was detected with different levels corresponding to different stimulation intensities. We kinetically dissected the recycling vesicle pool as sequentially connected sub-pools (readily priming pool, readily releasable pool, surface pool and post-endocytic pool) and depicted the complete kinetic structure. The sizes and transition rates among these sub-pools were dynamically regulated by neuronal activity, in order to ensure efficient synaptic transmission. Furthermore, the dissected kinetic structure of recycling vesicle pools was found to function as a low pass filter to “forget” the short history of synaptic activity and thus reduce the impact of previous synaptic activity on the ongoing synaptic transmission. Our work provided a new insight into the function of vesicle recycling that the machinery of vesicle recycling functions not only a vesicle provider but also a stabilizer of synaptic transmission to ensure short term plasticity based neuronal signaling.
