The concerted actions of Tip1/CLIP-170, Klp5/Kinesin-8, and Alp14/XMAP215 regulate microtubule catastrophe at the cell end.
The concerted actions of Tip1/CLIP-170, Klp5/Kinesin-8, and Alp14/XMAP215 regulate microtubule catastrophe at the cell end.
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Tip1/CLIP-170、Klp5/Kinesin-8 和 Alp14/XMAP215 的协同作用调节细胞末端的微管灾难
DOI：
10.1093/jmcb/mjz039
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发表时间：
2019
影响因子：
5.5
通讯作者：
Fu Chuanhai
中科院分区：
文献类型：
--
作者：
Niu Xiaojia;Zheng Fan;Fu Chuanhai
摘要微管突变的空间调控对于控制微管长度，从而有助于细胞极性的正确建立和细胞生长具有重要意义。包括Tip 1/CLIP-170、Klp 5/Kinesin-8和Alp 14/XMAP 215的+TIP蛋白位于微管正末端以调节微管动力学。在裂殖酵母裂殖酵母中，Tip 1和Alp 14作为微管稳定因子，而Klp 5作为灾难促进因子起相反的作用。尽管Tip 1已被证明在限制微管灾难到细胞末端方面发挥关键作用，但Tip 1如何发挥作用仍有待确定。采用活细胞显微镜，我们发现，Tip 1的情况下，损害本地化的Klp 5和Alp 14在微管加结束，但Klp 5的情况下，Tip 1的停留时间在微管加结束。我们进一步揭示了Klp 5以Tip 1依赖性方式在微管正末端的Tip 1后面积累。此外，人工将Klp 5拴系到微管正末端促进了微管的过早突变，而将Alp 14拴系到缺乏Tip 1的细胞中的微管正末端则挽救了短微管的表型。这些发现证实Tip 1可能通过在空间上限制Klp 5的微管突变活性并稳定微管正末端的Alp 14来将微管突变限制在细胞末端。因此，这项工作证明了Tip 1，Alp 14和Klp 5在确保细胞末端微管灾难中的协调作用。
Abstract Spatial regulation of microtubule catastrophe is important for controlling microtubule length and consequently contributes to the proper establishment of cell polarity and cell growth. The +TIP proteins including Tip1/CLIP-170, Klp5/Kinesin-8, and Alp14/XMAP215 reside at microtubule plus ends to regulate microtubule dynamics. In the fission yeast Schizosaccharomyces pombe, Tip1 and Alp14 serve as microtubule-stabilizing factors, while Klp5 functions oppositely as a catastrophe-promoting factor. Despite that Tip1 has been shown to play a key role in restricting microtubule catastrophe to the cell end, how Tip1 fulfills the role remains to be determined. Employing live-cell microscopy, we showed that the absence of Tip1 impairs the localization of both Klp5 and Alp14 at microtubule plus ends, but the absence of Klp5 prolongs the residence time of Tip1 at microtubule plus ends. We further revealed that Klp5 accumulates behind Tip1 at microtubule plus ends in a Tip1-dependent manner. In addition, artificially tethering Klp5 to microtubule plus ends promotes premature microtubule catastrophe, while tethering Alp14 to microtubule plus ends in the cells lacking Tip1 rescues the phenotype of short microtubules. These findings establish that Tip1 restricts microtubule catastrophe to the cell end likely by spatially restricting the microtubule catastrophe activity of Klp5 and stabilizing Alp14 at microtubule plus ends. Thus, the work demonstrates the orchestration of Tip1, Alp14, and Klp5 in ensuring microtubule catastrophe at the cell end.