Axonal transport of mitochondria along microtubules and F-actin in living vertebrate neurons.
Axonal transport of mitochondria along microtubules and F-actin in living vertebrate neurons.
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DOI：
10.1083/jcb.131.5.1315
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发表时间：
1995-12
期刊：
影响因子：
--
通讯作者：
Hollenbeck PJ
中科院分区：
文献类型：
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作者：
Morris RL;Hollenbeck PJ
大量证据表明微管（MTs）在轴突中进行细胞器运输，但最近对挤出的鱿鱼轴质的研究表明，肌动蛋白微丝（MFs）可能也在这一过程中起作用。为了研究每类细胞骨架成分在完整脊椎动物轴突运输中的单独作用，我们监测了经过实验处理以去除微管、微丝或两者的鸡交感神经元中的线粒体运动。首先，我们在以下持续存在的条件下培养神经元：（a）细胞松弛素E，以产生从未含有微丝的神经突；或（b）诺考达唑或长春碱，以产生从未含有微管的神经突。线粒体在含有微管且缺乏微丝的神经突长度方向上以正常速度双向移动，但甚至不会进入没有微管但含有微丝的神经突。在第二种方法中，我们用细胞骨架药物处理已建立的神经元培养物，以破坏已经含有线粒体的轴突中的微管或微丝。在保留微管但缺乏微丝的细胞松弛素处理的细胞中，线粒体双向的平均速度增加，但净方向运输减少。在缺乏微管但基本保留正常水平微丝的长春碱处理的细胞中，线粒体继续双向移动，但双向移动的线粒体平均速度和移动距离都减少，并且线粒体逆行移动的时间是顺行移动时间的三倍，导致净逆行运输。用两种药物处理已建立的培养物产生了缺乏微管和微丝但仍然富含神经丝的神经突；这些神经突显示出明显缺乏任何线粒体运动性。这些数据表明，轴突细胞器运输在体内可以沿着微管和微丝进行，但具有不同的速度和净运输特性。
A large body of evidence indicates that microtubules (MTs) conduct organelle transport in axons, but recent studies on extruded squid axoplasm have suggested that actin microfilaments (MFs) may also play a role in this process. To investigate the separate contributions to transport of each class of cytoskeletal element in intact vertebrate axons, we have monitored mitochondrial movements in chick sympathetic neurons experimentally manipulated to eliminate MTs, MFs, or both. First, we grew neurons in the continuous presence of: (a) cytochalasin E to create neurites which had never contained MFs; or (b) nocodazole or vinblastine to produce neurites which had never contained MTs. Mitochondria moved bidirectionally at normal velocities along the length of neurites which contained MTs and lacked MFs, but did not even enter neurites grown without MTs but containing MFs. In a second approach, we treated established neuronal cultures with cytoskeletal drugs to disrupt either MTs or MFs in axons already containing mitochondria. In cytochalasin-treated cells, which retained MTs but lacked MFs, average mitochondrial velocity increased in both directions, but net directional transport decreased. In vinblastine- treated cells, which lacked MTs but retained essentially normal levels of MFs, mitochondria continued to move bidirectionally but the average mitochondrial velocity and excursion length were reduced for both directions of movement, and the mitochondria spent threefold as much time moving in the retrograde as in the anterograde direction, resulting in net retrograde transport. Treatment of established cultures with both drugs produced neurites lacking MTs and MFs but still rich in neurofilaments; these showed a striking absence of any mitochondrial motility. These data indicate that axonal organelle transport can occur along both MTs and MFs in vivo, but with different velocities and net transport properties.