The function of the nervous system relies on synaptic transmission. Synaptic transmission is mediated by calcium-triggered vesicle fusion, followed by vesicle endocytosis that recycles vesicles. Although significant progress has been made in understanding these processes, much remains unknown. My goal is to advance our understanding of these synaptic signaling processes. The progress of the last year is described below. Studies over the last decade using FM dyes to label vesicles at many terminals, including the calyx-type nerve terminal, led to a well-accepted principle that only a small fraction of vesicles (5-20%) participate in recycling under physiological conditions. This principle imposes a large challenge in maintaining synaptic transmission during repetitive firing, because the small recycling pool may limit the number of available vesicles for release and nerve terminals would have to distinguish the recycling pool from the reserve pool and keep reserve pool vesicles from being used. By recording the presynaptic capacitance changes and the postsynaptic EPSC at rat calyx of Held synapses in the absence or presence of transmitter glutamate in nerve terminals, we developed a new method to count functional recycling vesicles. We found that essentially all vesicles in calyces participated in recycling, challenging the small-recycling-pool principle established by FM dye labeling. Nerve terminals may utilize all available vesicles to maximize their ability in maintaining synaptic transmission during repetitive firing.

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Wen, Peter J; Grenklo, Staffan; Arpino, Gianvito et al. (2016) Actin dynamics provides membrane tension to merge fusing vesicles into the plasma membrane. Nat Commun 7:12604
Baydyuk, Maryna; Xu, Jianhua; Wu, Ling-Gang (2016) The calyx of Held in the auditory system: Structure, function, and development. Hear Res 338:22-31
Zhao, Wei-Dong; Hamid, Edaeni; Shin, Wonchul et al. (2016) Hemi-fused structure mediates and controls fusion and fission in live cells. Nature 534:548-52
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Baydyuk, Maryna; Wu, Xin-Sheng; He, Liming et al. (2015) Brain-derived neurotrophic factor inhibits calcium channel activation, exocytosis, and endocytosis at a central nerve terminal. J Neurosci 35:4676-82
Wu, Ling-Gang; Hamid, Edaeni; Shin, Wonchul et al. (2014) Exocytosis and endocytosis: modes, functions, and coupling mechanisms. Annu Rev Physiol 76:301-31
Xiong, Wei; Chen, Shao-Rui; He, Liming et al. (2014) Presynaptic glycine receptors as a potential therapeutic target for hyperekplexia disease. Nat Neurosci 17:232-9
Cai, Zhenyu; Jitkaew, Siriporn; Zhao, Jie et al. (2014) Plasma membrane translocation of trimerized MLKL protein is required for TNF-induced necroptosis. Nat Cell Biol 16:55-65
Zhou, Di; Zhang, Zhen; He, Li-Ming et al. (2014) Conversion of fibroblasts to neural cells by p53 depletion. Cell Rep 9:2034-42
Sun, Chong-Kui; Zhou, Di; Zhang, Zhen et al. (2014) Senescence impairs direct conversion of human somatic cells to neurons. Nat Commun 5:4112

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