One at a time, live tracking of NGF axonal transport using quantum dots
One at a time, live tracking of NGF axonal transport using quantum dots
复制标题
DOI：
10.1073/pnas.0706192104
复制
发表时间：
2007-08-21
影响因子：
11.1
通讯作者：
Chu, Steven
中科院分区：
文献类型：
--
作者：
Cui, Bianxiao;Wu, Chengbiao;Chu, Steven
神经生长因子（NGF）信号的轴突逆行转运对于外周交感神经元和感觉神经元以及基底前脑胆碱能神经元的存活、分化和维持至关重要。然而，神经生长因子信号从轴突末梢传播到细胞体的机制尚未完全阐明。为了深入了解其作用机制，我们采用量子点标记的神经生长因子（QD-NGF）对大鼠背根神经节（DRG）神经元进行了真实的实时追踪。我们的研究表明，主动运输的神经生长因子轴突的特点是快速，单向运动中断频繁的停顿。几乎所有的运动都是逆行的，但偶尔观察到短距离的顺行运动。令人惊讶的是，在单分子水平的定量分析表明，大多数含有NGF的内体只含有一个单一的NGF二聚体。电子显微镜分析轴突囊泡携带QD-NGF证实了这一发现。发现大多数QD-NGF定位于直径为50-150 nm的囊泡中，具有单腔并且没有可见的腔内膜组分。我们的研究结果指出，一个单一的神经生长因子二聚体的可能性是足以维持信号在逆行轴突运输到细胞体。
Retrograde axonal transport of nerve growth factor (NGF) signals is critical for the survival, differentiation, and maintenance of peripheral sympathetic and sensory neurons and basal forebrain cholinergic neurons. However, the mechanisms by which the NGF signal is propagated from the axon terminal to the cell body are yet to be fully elucidated. To gain insight into the mechanisms, we used quantum dot-labeled NGF (QD-NGF) to track the movement of NGF in real time in compartmentalized culture of rat dorsal root ganglion (DRG) neurons. Our studies showed that active transport of NGF within the axons was characterized by rapid, unidirectional movements interrupted by frequent pauses. Almost all movements were retrograde, but short-distance anterograde movements were occasionally observed. Surprisingly, quantitative analysis at the single molecule level demonstrated that the majority of NGF-containing endosomes contained only a single NGF dimer. Electron microscopic analysis of axonal vesicles carrying QD-NGF confirmed this finding. The majority of QD-NGF was found to localize in vesicles 50-150 nm in diameter with a single lumen and no visible intralumenal membranous components. Our findings point to the possibility that a single NGF dimer is sufficient to sustain signaling during retrograde axonal transport to the cell body.