TOMOGRAPHY OF ENDOCYTIC INTERMEDIATES IN NERVE TERMINALS

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 Dynamin 1是一种神经元特异性的鸟苷三磷酸酶，被认为是突触囊泡内吞的裂变反应所必需的。出乎意料的是，缺乏Dynamin 1的小鼠能够形成功能性突触，尽管它们出生后的生存能力有限。然而，在自发的网络活动中，在Dynamin 1基因敲除小鼠的突触中观察到复杂的管状囊泡内陷。用连续电子断层扫描进行的三维分析进一步显示，在这些突触中积累了分支的管状质膜内陷，这些突触被笼罩着网状蛋白的凹陷所覆盖。突触囊泡内吞作用在强外源性刺激时受到严重损害，但在刺激终止后有效地恢复。因此，Dynamin 1不依赖的机制可以支持有限的突触小泡内吞作用，但Dynamin 1在高水平的神经元活动中是必需的。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Dynamin 1 is a neuron-specific guanosine triphosphatase thought to be critically required for the fission reaction of synaptic vesicle endocytosis. Unexpectedly, mice lacking dynamin 1 were able to form functional synapses, even though their postnatal viability was limited. However, during spontaneous network activity, complex tubular vesicular invaginations were observed in synapses of dynamin 1knockout mice. A 3-D analysis using serial, electron tomography further revealed that branched, tubular plasma membrane invaginations accumulated in these mutant synapses, and these were capped by clathrin-coated pits. Synaptic vesicle endocytosis was severely impaired during strong exogenous stimulation but resumed efficiently when the stimulus was terminated. Thus, dynamin 1independent mechanisms can support limited synaptic vesicle endocytosis, but dynamin 1 is needed during high levels of neuronal activity.