Endosomal compartments serve multiple hippocampal dendritic spines from a widespread rather than a local store of recycling membrane
Endosomal compartments serve multiple hippocampal dendritic spines from a widespread rather than a local store of recycling membrane
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DOI：
10.1523/jneurosci.22-06-02215.2002
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发表时间：
2002-03-15
影响因子：
5.3
通讯作者：
Fiala, JC
中科院分区：
文献类型：
--
作者：
Cooney, JR;Hurlburt, JL;Fiala, JC
内体在分选膜蛋白以进行降解或再循环方面对树突和突触功能至关重要，但人们对其在突触附近的位置知之甚少。在此，利用连续电子显微镜来确定幼年和成年大鼠海马CA1锥体神经元远端树突中所有膜性细胞内区室的形态和分布。首先，在整个树突节段及其棘突中追踪平滑内质网（SER）的连续网络。SER占据树突干的皮质并延伸到14%的棘突中。然后鉴定出几种非SER区室类型，包括网格蛋白包被的囊泡和凹陷、大型无包被囊泡、管状区室、多泡体（MVBs）以及MVB - 小管复合物。细胞外金颗粒的摄取表明这些区室起源于内体。还鉴定出不含金的小而圆的囊泡和凹陷。管状区室显示出网格蛋白包被的末端，这与这些可能是外泌体的小囊泡的产生一致。大约70%的非SER区室位于树突棘内部或基部。总体而言，只有29%的树突棘具有内体区室，而20%含有小囊泡。小囊泡在棘突中不与内体或SER共定位。三维重建显示，多达20个棘突共享一个质膜蛋白再循环池，而不是在每个棘突维持独立的储存。
Endosomes are essential to dendritic and synaptic function in sorting membrane proteins for degradation or recycling, yet little is known about their locations near synapses. Here, serial electron microscopy was used to ascertain the morphology and distribution of all membranous intracellular compartments in distal dendrites of hippocampal CA1 pyramidal neurons in juvenile and adult rats. First, the continuous network of smooth endoplasmic reticulum (SER) was traced throughout dendritic segments and their spines. SER occupied the cortex of the dendritic shaft and extended into 14% of spines. Several types of non-SER compartments were then identified, including clathrin-coated vesicles and pits, large uncoated vesicles, tubular compartments, multivesicular bodies (MVBs), and MVB-tubule complexes. The uptake of extracellular gold particles indicated that these compartments were endosomal in origin. Small, round vesicles and pits that did not contain gold were also identified. The tubular compartments exhibited clathrin-coated tips consistent with the genesis of these small, presumably exosomal vesicles. Approximately 70% of the non-SER compartments were located within or at the base of dendritic spines. Overall, only 29% of dendritic spines had endosomal compartments, whereas 20% contained small vesicles. Small vesicles did not colocalize in spines with endosomes or SER. Three-dimensional reconstructions revealed that up to 20 spines shared a recycling pool of plasmalemmal proteins rather than maintaining independent stores at each spine.