Restricted growth of Schwann cells lacking Cajal bands slows conduction in myelinated nerves
Restricted growth of Schwann cells lacking Cajal bands slows conduction in myelinated nerves
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DOI：
10.1038/nature02841
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发表时间：
2004-09-09
期刊：
影响因子：
64.8
通讯作者：
Brophy, PJ
中科院分区：
文献类型：
--
作者：
Court, FA;Sherman, DL;Brophy, PJ
神经冲动在脊椎动物有髓神经的兰维尔结点传播。节间距离已被提出影响神经冲动传导的速度[1]；然而，缺乏直接证据，可能调节有髓节段长度的细胞机制尚不清楚。Ramon y Cajal描述了节间雪旺细胞中细胞质或小梁的纵带和横带，并暗示它们具有营养功能[2]。在这里，我们展示了野生型神经的节间生长与神经延伸精确匹配，但在Periaxin缺失的小鼠中，细胞质带的破坏损害了神经生长过程中雪旺细胞的延长。相比之下，髓鞘形成则正常进行。野生型和突变型雪旺细胞的伸长能力是细胞自主的，表明被动伸展可以解释肢体生长过程中节间的延长。正如理论预测的那样，结节间距离的减少会显著降低传导速度，从而影响运动功能。我们认为，Cajal纵带中基于微管的运输允许节点间雪旺细胞随着轴突的生长而延长，从而确保神经冲动的快速传递。
Nerve impulses are propagated at nodes of Ranvier in the myelinated nerves of vertebrates. Internodal distances have been proposed to affect the velocity of nerve impulse conduction(1); however, direct evidence is lacking, and the cellular mechanisms that might regulate the length of the myelinated segments are unknown. Ramon y Cajal described longitudinal and transverse bands of cytoplasm or trabeculae in internodal Schwann cells and suggested that they had a nutritive function(2). Here we show that internodal growth in wild-type nerves is precisely matched to nerve extension, but disruption of the cytoplasmic bands in Periaxin-null mice impairs Schwann cell elongation during nerve growth. By contrast, myelination proceeds normally. The capacity of wild-type and mutant Schwann cells to elongate is cell-autonomous, indicating that passive stretching can account for the lengthening of the internode during limb growth. As predicted on theoretical grounds, decreased internodal distances strikingly decrease conduction velocities and so affect motor function. We propose that microtubule-based transport in the longitudinal bands of Cajal permits internodal Schwann cells to lengthen in response to axonal growth, thus ensuring rapid nerve impulse transmission.