发育过程中突触前钙通道的纳米级分布及其对囊泡释放的影响。
Nanoscale distribution of presynaptic Ca(2+) channels and its impact on vesicular release during development.
作者信息
Nakamura Yukihiro, Harada Harumi, Kamasawa Naomi, Matsui Ko, Rothman Jason S, Shigemoto Ryuichi, Silver R Angus, DiGregorio David A, Takahashi Tomoyuki
机构信息
Laboratory of Molecular Synaptic Function, Graduate School of Brain Science, Doshisha University, Kyoto 610-0394, Japan; Cellular & Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology (OIST) Graduate University, Okinawa 904-0495, Japan; Laboratory of Dynamic Neuronal Imaging, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris Cedex 15, France; CNRS UMR 3571, 25 rue du Dr Roux, 75724 Paris Cedex 15, France.
Division of Cerebral Structure, Department of Cerebral Research, National Institute for Physiological Sciences, Myodaiji, Okazaki 444-8787, Japan; Institute of Science and Technology Austria, A-3400 Klosterneuburg, Austria.
出版信息
Neuron. 2015 Jan 7;85(1):145-158. doi: 10.1016/j.neuron.2014.11.019. Epub 2014 Dec 18.
Synaptic efficacy and precision are influenced by the coupling of voltage-gated Ca(2+) channels (VGCCs) to vesicles. But because the topography of VGCCs and their proximity to vesicles is unknown, a quantitative understanding of the determinants of vesicular release at nanometer scale is lacking. To investigate this, we combined freeze-fracture replica immunogold labeling of Cav2.1 channels, local [Ca(2+)] imaging, and patch pipette perfusion of EGTA at the calyx of Held. Between postnatal day 7 and 21, VGCCs formed variable sized clusters and vesicular release became less sensitive to EGTA, whereas fixed Ca(2+) buffer properties remained constant. Experimentally constrained reaction-diffusion simulations suggest that Ca(2+) sensors for vesicular release are located at the perimeter of VGCC clusters (<30 nm) and predict that VGCC number per cluster determines vesicular release probability without altering release time course. This "perimeter release model" provides a unifying framework accounting for developmental changes in both synaptic efficacy and time course.
突触效能和精确性受电压门控钙通道（VGCCs）与囊泡的偶联影响。但由于VGCCs的拓扑结构及其与囊泡的接近程度未知，因此缺乏对纳米尺度下囊泡释放决定因素的定量认识。为了研究这一点，我们在Held壶腹处结合了Cav2.1通道的冷冻断裂复制品免疫金标记、局部[Ca(2+)]成像以及EGTA的膜片吸管灌注。在出生后第7天至21天之间，VGCCs形成了大小可变的簇，并且囊泡释放对EGTA的敏感性降低，而固定的Ca(2+)缓冲特性保持不变。实验约束的反应扩散模拟表明，用于囊泡释放的Ca(2+)传感器位于VGCC簇的周边（<30 nm），并预测每个簇的VGCC数量决定囊泡释放概率，而不会改变释放时间进程。这种“周边释放模型”提供了一个统一的框架，解释了突触效能和时间进程的发育变化。
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