The Functional Antagonism between Eg5 and Dynein in Spindle Bipolarization Is Not Compatible with a Simple Push-Pull Model
The Functional Antagonism between Eg5 and Dynein in Spindle Bipolarization Is Not Compatible with a Simple Push-Pull Model
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DOI：
10.1016/j.celrep.2012.03.006
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发表时间：
2012-05-01
期刊：
影响因子：
8.8
通讯作者：
Mayer, Thomas U.
中科院分区：
文献类型：
--
作者：
Florian, Stefan;Mayer, Thomas U.
在细胞分裂过程中，分子马达 Eg5 交联重叠的反平行微管，并将它们推开以分离有丝分裂纺锤体极。动力蛋白被认为是纺锤体赤道处 Eg5 的直接拮抗剂，拉动反平行微管并有利于纺锤体塌陷。支持这一假设的一些实验依赖于纺锤体表型的终点定量，而不是随着时间的推移跟踪单个细胞的命运。在这里，我们提出了一个数学模型和原理验证实验，以证明终点量化可能从根本上误导，因为它们高估了有缺陷的表型。事实上，活细胞成像表明，虽然动力蛋白或动力蛋白结合蛋白 Lis1 的消耗能够在 Eg5 抑制剂存在的情况下形成纺锤体，但动力蛋白和 Eg5 的活性不能相互滴定。因此，动力蛋白很可能通过在不同纺锤体位置施加力来间接拮抗Eg5，而不是通过纺锤体赤道处的简单推拉机制。
During cell division, the molecular motor Eg5 crosslinks overlapping antiparallel microtubules and pushes them apart to separate mitotic spindle poles. Dynein has been proposed as a direct antagonist of Eg5 at the spindle equator, pulling on antiparallel microtubules and favoring spindle collapse. Some of the experiments supporting this hypothesis relied on endpoint quantifications of spindle phenotypes rather than following individual cell fates over time. Here, we present a mathematical model and proof-of-principle experiments to demonstrate that endpoint quantifications can be fundamentally misleading because they overestimate defective phenotypes. Indeed, live-cell imaging reveals that, while depletion of dynein or the dynein binding protein Lis1 enables spindle formation in presence of an Eg5 inhibitor, the activities of dynein and Eg5 cannot be titrated against each other. Thus, dynein most likely antagonizes Eg5 indirectly by exerting force at different spindle locations rather than through a simple push-pull mechanism at the spindle equator.