Augmin accumulation on long-lived microtubules drives amplification and kinetochore-directed growth
Augmin accumulation on long-lived microtubules drives amplification and kinetochore-directed growth
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DOI：
10.1083/jcb.201805044
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发表时间：
2019-07-01
影响因子：
7.8
通讯作者：
Gerlich, Daniel W.
中科院分区：
文献类型：
--
作者：
David, Ana F.;Roudot, Philippe;Gerlich, Daniel W.
分裂细胞将它们的微管细胞骨架重组成两极纺锤形，将一组姐妹染色单体移动到每个新生的子细胞上。早期的纺锤体组装模型假设纺锤体极点衍生的微管搜索细胞质空间，直到它们随机遇到动粒形成稳定的连接。最近的工作发现了另外几条中心体独立的微管生成途径，但每条途径对纺锤体组装的作用尚不清楚。在这里，我们结合活显微镜和数学模型显示，在分裂人类细胞时，大多数微管在非中心体区成核。使用选择性标记老化微管晶格的活细胞探针，我们证明生长中的微管+末端的分布几乎可以完全由长寿命微管晶格的Augmin依赖的放大来解释。用超快3D晶格光片显微镜观察到，这一机制导致了微管生长对单个动点的强烈定向偏向。我们对纺锤体动力学的系统量化揭示了动粒纤维组装过程中微管的高度协调生长。
Dividing cells reorganize their microtubule cytoskeleton into a bipolar spindle, which moves one set of sister chromatids to each nascent daughter cell. Early spindle assembly models postulated that spindle pole-derived microtubules search the cytoplasmic space until they randomly encounter a kinetochore to form a stable attachment. More recent work uncovered several additional, centrosome-independent microtubule generation pathways, but the contributions of each pathway to spindle assembly have remained unclear. Here, we combined live microscopy and mathematical modeling to show that most microtubules nucleate at noncentrosomal regions in dividing human cells. Using a live-cell probe that selectively labels aged microtubule lattices, we demonstrate that the distribution of growing microtubule plus ends can be almost entirely explained by Augmin-dependent amplification of long-lived microtubule lattices. By ultrafast 3D lattice light-sheet microscopy, we observed that this mechanism results in a strong directional bias of microtubule growth toward individual kinetochores. Our systematic quantification of spindle dynamics reveals highly coordinated microtubule growth during kinetochore fiber assembly.