Lardong K, Maas C, Kneussel M
Zentrum für Molekulare Neurobiologie Hamburg, ZMNH, Universität Hamburg, Falkenried 94, D-20251 Hamburg, Germany.
Neuroscience. 2009 Apr 21;160(1):1-5. doi: 10.1016/j.neuroscience.2009.02.034. Epub 2009 Feb 27.
Active neuronal transport along microtubules participates in the targeting of mRNAs, proteins and organelles to their sites of action. Cytoplasmic dynein represents a minus-end-directed microtubule-dependent motor protein. Due to the polarity of microtubules in axonal and distal dendritic compartments, with microtubule minus-ends pointing toward the inside of the cell, dyneins mainly mediate retrograde transport pathways in neurons. Since dyneins transport synaptic proteins, we asked whether changes in neuronal activity would in general influence dynein transport. KCl-induced depolarization, a condition that mimics the effects of neuronal activity, or pharmacological blockade of neuronal action potentials, respectively, was combined with neuronal live cell imaging, using an autofluorescent dynein intermediate chain fusion (monomeric red fluorescent protein [mRFP]-dynein intermediate chain [DIC]) as a model protein. Notably, we found that induced activity significantly reduced dynein particle mobility, as well as both the total distance and velocity of movements in mouse cultured hippocampal neurons. In contrast, blockade of neuronal action potentials through TTX did not alter any of the parameters analyzed. Neuronal depolarization processes therefore represent candidate mechanisms to regulate intracellular transport of neuronal cargoes.
沿着微管的活跃神经元运输参与了信使核糖核酸、蛋白质和细胞器向其作用位点的靶向运输。胞质动力蛋白是一种依赖微管的向负端运动的马达蛋白。由于轴突和远端树突区室中微管的极性，微管负端指向细胞内部，动力蛋白主要介导神经元中的逆行运输途径。鉴于动力蛋白运输突触蛋白，我们探究神经元活动的变化是否通常会影响动力蛋白运输。分别将氯化钾诱导的去极化（一种模拟神经元活动效应的状态）或神经元动作电位的药理学阻断与神经元活细胞成像相结合，使用一种自发荧光的动力蛋白中间链融合体（单体红色荧光蛋白[mRFP] - 动力蛋白中间链[DIC]）作为模型蛋白。值得注意的是，我们发现诱导的活动显著降低了动力蛋白颗粒的移动性，以及小鼠培养海马神经元中运动的总距离和速度。相比之下，通过河豚毒素阻断神经元动作电位并未改变所分析的任何参数。因此，神经元去极化过程代表了调节神经元货物细胞内运输的候选机制。
