Localized Mechanical Stress Promotes Microtubule Rescue
Localized Mechanical Stress Promotes Microtubule Rescue
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DOI：
10.1016/j.cub.2016.10.048
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发表时间：
2016-12-19
期刊：
影响因子：
9.2
通讯作者：
Pous, Christian
中科院分区：
文献类型：
--
作者：
de Forges, Helene;Pilon, Antoine;Pous, Christian
微管的动力学依赖于微管蛋白的性质，并受微管相关蛋白的调节。GTP-微管蛋白可以组装成中空聚合物，在GTP水解后可以解聚。解聚微管可能会停止收缩并恢复生长。这样的救援是由微管相关蛋白调节的，如CLIP-170和CLASPS[1，2]。易于挽救的微管结构域包含在微管主体中保持GTP-微管蛋白样构象的离散区域(以前称为“GTP岛”)[3]。然而，这些结构域的确切性质以及控制其发生和分布的机制在很大程度上尚不清楚。在这里，我们表明，在体外生长的微管与机械障碍(包括其他微管)之间的碰撞导致了应力微管区域中更高的GTP样岛的丰度。此外，这些岛被发现是由施加在微管主体上的横向接触和机械约束有效地产生的。当微管晶格中的原丝数量发生变化时，它们也特别突出。GTP样岛和救援经常出现在体外的微管交叉处和活细胞中，无论是交叉微管还是交叉微管。我们还观察到，CLIP-170在体内识别GTP样岛并保留在微管交叉处。因此，我们认为救援通过两个阶段的机制发生：(1)晶格缺陷决定微管结构中潜在的促进救援的岛，(2)CLIP-170检测这些岛以刺激微管救援。我们的结果揭示了救援促进因子与微管结构和组织之间的相互作用，以控制微管动力学。
Microtubule dynamics rely on the properties of tubulin and are regulated by microtubule-associated proteins. GTP-tubulin assembles into hollow polymers, which can depolymerize upon GTP hydrolysis. Depolymerizing microtubules may stop shrinking and resume growth. Such rescues are regulated by microtubule-associated proteins like CLIP-170 and the CLASPs [1, 2]. Microtubule domains prone to rescues contain discrete regions (previously termed "GTP islands'') that retain a GTP-tubulin-like conformation in the main body of the microtubule [3]. However, the exact nature of these domains and the mechanisms controlling their occurrence and distribution are largely unknown. Here we show that collisions between growing microtubules and mechanical obstacles (including other microtubules) in vitro result in the higher abundance of GTP-like islands in stressed microtubule regions. Furthermore, these islands were found to be efficiently generated by both lateral contacts and mechanical constraints applied to the main body of the microtubules. They were also particularly prominent where shifts in the number of protofilaments occur in the microtubule lattice. GTP-like islands and rescues frequently co-occurred at microtubule intersections in vitro and in living cells, both in crossing and in crossed microtubules. We also observed that CLIP-170 recognizes GTP-like islands in vivo and is retained at microtubule crossings. Therefore, we propose that rescues occur via a two-stage mechanism: (1) lattice defects determine potential rescue-promoting islands in the microtubule structure, and (2) CLIP-170 detects these islands to stimulate microtubule rescue. Our results reveal the interplay between rescue-promoting factors and microtubule architecture and organization to control microtubule dynamics.