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Effects of malleable kinetochore morphology on measurements of intrakinetochore tension.
Open Biology ( IF 5.8 ) Pub Date : 2020-07-08 , DOI: 10.1098/rsob.200101
Fioranna Renda 1 , Valentin Magidson 1 , Irina Tikhonenko 1 , Rebecca Fisher 1 , Christopher Miles 2 , Alex Mogilner 2 , Alexey Khodjakov 1, 3
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The distance between fluorescent spots formed by various kinetochore proteins (delta) is commonly interpreted as a manifestation of intrakinetochore tension (IKT) caused by microtubule-mediated forces. However, large-scale changes of the kinetochore architecture (such as its shape or dimensions) may also contribute to the value of delta. To assess contributions of these non-elastic changes, we compare behaviour of delta values in human kinetochores with small yet mechanically malleable kinetochores against compound kinetochores in Indian muntjac (IM) cells whose architecture remains constant. Due to the micrometre-scale length of kinetochore plates in IM, their shape and orientation are discernible in conventional light microscopy, which enables precise measurements of IKT independent of contributions from changes in overall architecture of the organelle. We find that delta in IM kinetochores remains relatively constant when microtubule-mediated forces are suppressed by Taxol, but it prominently decreases upon detachment of microtubules. By contrast, large decreases of delta observed in Taxol-treated human cells coincide with prominent changes in length and curvature of the kinetochore plate. These observations, supported by computational modelling, suggest that at least 50% of the decrease in delta in human cells reflects malleable reorganization of kinetochore architecture rather than elastic recoil due to IKT.



中文翻译:

可塑性动粒形态对动粒内张力测量的影响。

由各种动粒蛋白 (delta) 形成的荧光点之间的距离通常被解释为由微管介导的力引起的动粒内张力 (IKT) 的表现。然而,动粒架构的大规模变化(例如其形状或尺寸)也可能对 delta 值有影响。为了评估这些非弹性变化的贡献,我们比较了具有小但机械可塑性的动粒的人类动粒的 delta 值与结构保持不变的印度麂 (IM) 细胞中的复合动粒的行为。由于 IM 中动粒板的微米级长度,它们的形状和方向在传统的光学显微镜中是可辨别的,这可以精确测量 IKT,而不受细胞器整体结构变化的影响。我们发现当微管介导的力被紫杉醇抑制时,IM 动粒中的 delta 保持相对恒定,但它在微管脱离时显着降低。相比之下,在紫杉醇处理的人类细胞中观察到的 delta 大幅下降与动粒板长度和曲率的显着变化相吻合。这些观察得到计算模型的支持,表明人类细胞中至少 50% 的 delta 减少反映了动粒结构的可塑性重组,而不是由于 IKT 引起的弹性反冲。但它在微管脱离后显着降低。相比之下,在紫杉醇处理的人类细胞中观察到的 delta 大幅下降与动粒板长度和曲率的显着变化相吻合。这些观察得到计算模型的支持,表明人类细胞中至少 50% 的 delta 减少反映了动粒结构的可塑性重组,而不是由于 IKT 引起的弹性反冲。但它在微管脱离后显着降低。相比之下,在紫杉醇处理的人类细胞中观察到的 delta 大幅下降与动粒板长度和曲率的显着变化相吻合。这些观察得到计算模型的支持,表明人类细胞中至少 50% 的 delta 减少反映了动粒结构的可塑性重组,而不是由于 IKT 引起的弹性反冲。

更新日期:2020-07-20
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