Dynein Antagonizes Eg5 by Crosslinking and Sliding Antiparallel Microtubules
Dynein Antagonizes Eg5 by Crosslinking and Sliding Antiparallel Microtubules
复制标题
DOI：
10.1016/j.cub.2009.09.025
复制
发表时间：
2009-11-17
期刊：
影响因子：
9.2
通讯作者：
Wadsworth, Patricia
中科院分区：
文献类型：
--
作者：
Ferenz, Nick P.;Paul, Raja;Wadsworth, Patricia
有丝分裂纺锤体组装需要各种分子运动蛋白的联合活性，包括 Eg5 [1] 和动力蛋白 [2]。这些电机在哺乳动物双极纺锤体组装过程中共同产生对抗力 [3]；然而，仍然未知的是这些马达如何在功能上协调，从而使对抗成为可能。鉴于 Eg5 通过交联和滑动反平行微管 (MT) 产生向外的力 [4-6]，我们探索了动力蛋白通过同样滑动反平行微管 (MT) 产生向内力的可能性。我们推断，反平行重叠，以及因此动力蛋白介导的力的大小，将与中心体之间的初始距离成反比。为了利用这种关系，我们利用诺考达唑冲洗测定来模拟纺锤体组装。我们发现Eg5抑制导致单极或双极纺锤体形成，具体取决于中心体最初分开的距离是否分别小于或大于5.5μm。数学模型预测在缺乏功能性 Eg5 的情况下也会出现相同的纺锤体双稳态，并且需要动力蛋白作用于反平行 MT 才能实现这一点。我们的结果表明，动力蛋白通过交联和滑动反平行 MT 与 Eg5 进行功能协调，这是动力蛋白在纺锤体组装框架内的一个新作用。
Mitotic spindle assembly requires the combined activity of various molecular motor proteins, including Eg5 [1] and dynein [2]. Together, these motors generate antagonistic forces during mammalian bipolar spindle assembly [3]; what remains unknown, however, is how these motors are functionally coordinated such that antagonism is possible. Given that Eg5 generates an outward force by crosslinking and sliding apart antiparallel microtubules (MTs) [4-6], we explored the possibility that dynein generates an inward force by likewise sliding antiparallel MTs. We reasoned that antiparallel overlap, and therefore the magnitude of a dynein-mediated force, would be inversely proportional to the initial distance between centrosomes. To capitalize on this relationship, we utilized a nocodazole washout assay to mimic spindle assembly. We found that Eg5 inhibition led to either monopolar or bipolar spindle formation, depending on whether centrosomes were initially separated by less than or greater than 5.5 mu m, respectively. Mathematical modeling predicted this same spindle bistability in the absence of functional Eg5 and required dynein acting on antiparallel MTs to do so. Our results suggest that dynein functionally coordinates with Eg5 by crosslinking and sliding antiparallel MTs, a novel role for dynein within the framework of spindle assembly.