Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455, USA.
Department of Molecular Cell Systems Biology, University of California, Riverside, Riverside, CA 92521, USA.
J Cell Sci. 2023 Aug 15;136(16). doi: 10.1242/jcs.261416. Epub 2023 Aug 17.
Accurate genome segregation in mitosis requires that all chromosomes are bioriented on the spindle. Cells monitor biorientation by sensing tension across sister centromeres. Chromosomes that are not bioriented have low centromere tension, which allows Aurora B (yeast Ipl1) to perform error correction that locally loosens kinetochore-microtubule attachments to allow detachment of microtubules and fresh attempts at achieving biorientation. However, it is not known whether low tension recruits Aurora B to centromeres or, alternatively, whether low tension directly activates Aurora B already localized at centromeres. In this work, we experimentally induced low tension in metaphase Saccharomyces cerevisiae yeast cells, then monitored Ipl1 localization. We find low tension recruits Ipl1 to centromeres. Furthermore, low tension-induced Ipl1 recruitment depended on Bub1, which is known to provide a binding site for Ipl1. In contrast, Top2, which can also recruit Ipl1 to centromeres, was not required. Our results demonstrate cells are sensitive to low tension at centromeres and respond by actively recruiting Ip1l for error correction.
在有丝分裂中，准确的基因组分离要求所有染色体都在纺锤体上双定向。细胞通过感知姐妹着丝粒之间的张力来监测双定向。未双定向的染色体着丝粒张力较低，这允许 Aurora B（酵母 Ipl1）进行错误校正，局部松开动粒微管附着，从而允许微管脱离，并重新尝试实现双定向。然而，目前尚不清楚低张力是招募 Aurora B 到着丝粒，还是直接激活已经定位在着丝粒上的 Aurora B。在这项工作中，我们在有丝分裂中期酿酒酵母细胞中实验性地诱导低张力，然后监测 Ipl1 的定位。我们发现低张力将 Ipl1 招募到着丝粒。此外，低张力诱导的 Ipl1 招募依赖于 Bub1，Bub1 已知是 Ipl1 的结合位点。相比之下，Top2 也可以将 Ipl1 招募到着丝粒，但不需要。我们的结果表明，细胞对着丝粒处的低张力敏感，并通过主动招募 Ip1l 进行错误校正来做出反应。
