Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, UK.
Data Analysis Group, School of Life Sciences, University of Dundee, Dundee, UK.
J Cell Biol. 2019 May 6;218(5):1531-1552. doi: 10.1083/jcb.201807125. Epub 2019 Mar 11.
When human cells enter mitosis, chromosomes undergo substantial changes in their organization to resolve sister chromatids and compact chromosomes. To comprehend the timing and coordination of these events, we need to evaluate the progression of both sister chromatid resolution and chromosome compaction in one assay. Here we achieved this by analyzing changes in configuration of marked chromosome regions over time, with high spatial and temporal resolution. This assay showed that sister chromatids cycle between nonresolved and partially resolved states with an interval of a few minutes during G2 phase before completing full resolution in prophase. Cohesins and WAPL antagonistically regulate sister chromatid resolution in late G2 and prophase while local enrichment of cohesin on chromosomes prevents precocious sister chromatid resolution. Moreover, our assay allowed quantitative evaluation of condensin II and I activities, which differentially promote sister chromatid resolution and chromosome compaction, respectively. Our assay reveals novel aspects of dynamics in mitotic chromosome resolution and compaction that were previously obscure in global chromosome assays.
当人类细胞进入有丝分裂时，染色体的组织会发生显著变化，以解决姐妹染色单体和压缩染色体的问题。为了理解这些事件的时间和协调，我们需要在一个实验中评估姐妹染色单体分离和染色体压缩的进展情况。在这里，我们通过分析标记染色体区域随时间的构型变化，以高空间和时间分辨率来实现这一目标。该实验表明，姐妹染色单体在 G2 期非分离和部分分离状态之间循环，间隔几分钟，然后在前期完全分离。黏合蛋白和 WAPL 在后期 G2 和前期拮抗调节姐妹染色单体的分离，而染色体上黏合蛋白的局部富集防止姐妹染色单体过早分离。此外，我们的实验还允许对 condensin II 和 I 的活性进行定量评估，它们分别促进姐妹染色单体的分离和染色体的压缩。我们的实验揭示了有丝分裂染色体分离和压缩动力学的新方面，这些方面在以前的整体染色体实验中是不清楚的。
