Three-dimensional architecture of presynaptic terminal cytomatrix
Three-dimensional architecture of presynaptic terminal cytomatrix
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DOI：
10.1523/jneurosci.1773-07.2007
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发表时间：
2007-06-27
影响因子：
5.3
通讯作者：
Marty, Serge
中科院分区：
文献类型：
--
作者：
Siksou, Lea;Rostaing, Philippe;Marty, Serge
突触前终末是介导钙离子内流后突触囊泡（SV）快速融合的特化细胞。受管制的SV贩运可能是高度组织化的细胞基质的结果。如何这个cytomatrix链接SV，保持他们附近的活动区（AZ）的释放，并组织停靠在释放sites的SV是不完全understood.To分析的三维（3D）结构的突触前cytomatrix，电子断层扫描突触前末梢接触棘在放射层的大鼠海马CA1区。为了保存细胞基质，使用高压冷冻固定海马切片，然后进行冷冻置换和包埋。SV被密集的细丝网络包围。一个给定的囊泡与1.5个相邻的囊泡相连。在这个网络的外围的SV也通过较长的细丝连接到质膜。在AZ处发现更多的这些细丝。在AZ，停靠的SV围绕突触前密度分组。具有相邻SV的细丝从这些密度中出现。免疫金定位显示，突触蛋白位于突触前的终扣，而巴松管和CAST（ERC2）是在AZ旁边的焦点。在synapsin triple knockout小鼠中，SV的数量减少了63%，但终扣的大小仅减少了18%，SV到AZ的平均距离不变。SV在轴突终扣中紧密互连，并且该网络优先连接到AZ。
Presynaptic terminals are specialized for mediating rapid fusion of synaptic vesicles (SVs) after calcium influx. The regulated trafficking of SVs likely results from a highly organized cytomatrix. How this cytomatrix links SVs, maintains them near the active zones (AZs) of release, and organizes docked SVs at the release sites is not fully understood.To analyze the three-dimensional (3D) architecture of the presynaptic cytomatrix, electron tomography of presynaptic terminals contacting spines was performed in the stratum radiatum of the rat hippocampal CA1 area. To preserve the cytomatrix, hippocampal slices were immobilized using high-pressure freezing, followed by cryosubstitution and embedding. SVs are surrounded by a dense network of filaments. A given vesicle is connected to similar to 1.5 neighboring ones. SVs at the periphery of this network are also linked to the plasma membrane, by longer filaments. More of these filaments are found at the AZ. At the AZ, docked SVs are grouped around presynaptic densities. Filaments with adjacent SVs emerge from these densities. Immunogold localizations revealed that synapsin is located in the presynaptic bouton, whereas Bassoon and CAST( ERC2) are at focal points next to the AZ. In synapsin triple knock-out mice, the number of SVs is reduced by 63%, but the size of the boutons is reduced by only 18%, and the mean distance of SVs to the AZ is unchanged.This 3D analysis reveals the morphological constraints exerted by the presynaptic molecular scaffold. SVs are tightly interconnected in the axonal bouton, and this network is preferentially connected to the AZ.