Live imaging of marked chromosome regions reveals their dynamic resolution and compaction in mitosis

John Eykelenboom, Marek Gierlinski, Zuojun Yue, Nadia Hegarat, Hilary Pollard, Tatsuo Fukagawa, Helfrid Hochegger, Tomoyuki Tanaka (Lead / Corresponding author)

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Abstract

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.

Original languageEnglish
Pages (from-to)1531-1552
Number of pages22
JournalJournal of Cell Biology
Volume218
Issue number5
Early online date11 Mar 2019
DOIs
Publication statusPublished - 6 May 2019

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