Reorganization and movement of microtubules in axonal growth cones and developing interstitial branches
Reorganization and movement of microtubules in axonal growth cones and developing interstitial branches
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DOI：
10.1523/jneurosci.19-20-08894.1999
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发表时间：
1999-10-15
影响因子：
5.3
通讯作者：
Kalil, K
中科院分区：
文献类型：
--
作者：
Dent, EW;Callaway, JL;Kalil, K
轴突的适当生长和导航需要微管组织和分布的局部变化；然而，人们对微管（MT）在定向轴突生长过程中如何重组知之甚少。我们使用微注射荧光标记微管蛋白的发育中皮层神经元的延时数字成像来跟踪轴突两个发生定向生长的区域中单个 MT 的运动：末端生长锥和发育中的间质分支。在这两个区域，从静止状态到生长状态的转变都伴随着微管从环状或成束阵列到分散阵列的重组以及长微管分裂成短微管。我们还发现，MT 的长期重新分布伴随着一些轴突突起的撤回和其他轴突突起的生长和稳定。各个 MT 独立地沿顺行和逆行方向移动，探索发育过程。它们的速度与其长度成反比。我们的结果直接证明 MT 在轴突生长锥内移动并发育间质分支。我们的研究结果还提供了第一个直接证据，表明单个 MT 的类似重组和运动发生在轴突的两个发生定向生长的区域。这些结果表明，短的探索性 MT 可以将轴突生长锥和间质分支引导至适当的位置。
Local changes in microtubule organization and distribution are required for the axon to grow and navigate appropriately; however, little is known about how microtubules (MTs) reorganize during directed axon outgrowth. We have used time-lapse digital imaging of developing cortical neurons microinjected with fluorescently labeled tubulin to follow the movements of individual MTs in two regions of the axon where directed growth occurs: the terminal growth cone and the developing interstitial branch. In both regions, transitions from quiescent to growth states were accompanied by reorganization of MTs from looped or bundled arrays to dispersed arrays and fragmentation of long MTs into short MTs. We also found that long-term redistribution of MTs accompanied the withdrawal of some axonal processes and the growth and stabilization of others. Individual MTs moved independently in both anterograde and retrograde directions to explore developing processes. Their velocities were inversely proportional to their lengths. Our results demonstrate directly that MTs move within axonal growth cones and developing interstitial branches. Our findings also provide the first direct evidence that similar reorganization and movement of individual MTs occur in the two regions of the axon where directed outgrowth occurs. These results suggest a model whereby short exploratory MTs could direct axonal growth cones and interstitial branches toward appropriate locations.