Chromosome segregation is mediated by spindle microtubules that attach to the kinetochore via dynamic protein complexes, such as Ndc80, Ska, Cdt1 and ch‐TOG during mitotic metaphase. While experimental studies have previously shown that these proteins and protein complexes are all essential for maintaining a stable kinetochore‐microtubule (kMT) interface, their exact roles in the mitotic metaphase remains elusive. In this study, we employed experimental and computational methods in order to characterize how these proteins can strengthen kMT attachments in both nonload‐bearing and load‐bearing conditions, typical of prometaphase and metaphase, respectively. Immunofluorescence staining of HeLa cells showed that the levels of Ska and Cdt1 significantly increased from prometaphase to metaphase, while levels of the Ndc80 complex remained unchanged. Our new computational model showed that by incorporating binding and unbinding of each protein complex coupled with a biased diffusion mechanism, the displacement of a possible complex formed by Ndc80‐Ska‐Cdt1 is significantly higher than that of Ndc80 alone or Ndc80‐Ska. In addition, when we incorporate Ndc80/ch‐TOG in the model, rupture force and time of attachment of the kMT interface increases. These results support the hypothesis that Ndc80‐associated proteins strengthen kMT attachments, and that the interplay between kMT protein complexes in metaphase ensures stable attachments.

中文翻译：

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计算模型表明，Ndc80相关蛋白在中期增强了动粒体-微管的附着。

染色体分离是通过纺锤体微管介导的，该纺锤体微管在有丝分裂中期通过动态蛋白复合物（例如Ndc80，Ska，Cdt1和ch-TOG）附着在动粒上。尽管以前的实验研究表明，这些蛋白质和蛋白质复合物对于维持稳定的动粒微管（kMT）接口都是必不可少的，但它们在有丝分裂中期的确切作用仍然难以捉摸。在这项研究中，我们采用实验和计算方法来表征这些蛋白如何分别在前阶段和中期的非负荷和负荷条件下增强kMT附着。HeLa细胞的免疫荧光染色显示，从前中期到中期，Ska和Cdt1的水平显着增加，而Ndc80复合物的水平保持不变。我们的新计算模型表明，通过结合每种蛋白质复合物的结合和解结合以及偏向扩散机制，由Ndc80-Ska-Cdt1形成的可能复合物的位移明显高于单独的Ndc80或Ndc80-Ska。此外，当我们在模型中加入Ndc80 / ch-TOG时，kMT接口的断裂力和连接时间会增加。这些结果支持以下假设：与Ndc80相关的蛋白质增强了kMT的附着，并且中期的kMT蛋白质复合物之间的相互作用确保了稳定的附着。此外，在模型中加入Ndc80 / ch-TOG时，kMT接口的断裂力和连接时间会增加。这些结果支持以下假设：与Ndc80相关的蛋白质增强了kMT的附着，并且中期的kMT蛋白质复合物之间的相互作用确保了稳定的附着。此外，当我们在模型中加入Ndc80 / ch-TOG时，kMT接口的断裂力和连接时间会增加。这些结果支持以下假设：与Ndc80相关的蛋白质增强了kMT的附着，并且中期的kMT蛋白质复合物之间的相互作用确保了稳定的附着。