Abstract
Mitotic chromosome assembly remains a big mystery in biology. Condensin complexes are pivotal for chromosome architecture yet how they shape mitotic chromatin remains unknown. Using acute inactivation approaches and live-cell imaging in Drosophila embryos, we dissect the role of condensin I in the maintenance of mitotic chromosome structure with unprecedented temporal resolution. Removal of condensin I from pre-established chromosomes results in rapid disassembly of centromeric regions while most chromatin mass undergoes hyper-compaction. This is accompanied by drastic changes in the degree of sister chromatid intertwines. While wild-type metaphase chromosomes display residual levels of catenations, upon timely removal of condensin I, chromosomes present high levels of de novo Topoisomerase II (TopoII)-dependent re-entanglements, and complete failure in chromosome segregation. TopoII is thus capable of re-intertwining previously separated DNA molecules and condensin I continuously required to counteract this erroneous activity. We propose that maintenance of chromosome resolution is a highly dynamic bidirectional process.
Article and author information
Author details
Funding
Fundação para a Ciência e a Tecnologia (SRFH/BD/52172/2013)
- Ewa Piskadlo
European Commission (MCCIG321883/CCC)
- Raquel A Oliveira
European Molecular Biology Organization (IG2778)
- Raquel A Oliveira
Fundação para a Ciência e a Tecnologia (IF/00851/2012/CP0185/CT0004 WP1)
- Raquel A Oliveira
European Commission (ERC-2014-STG-638917-ChromoCellDev)
- Raquel A Oliveira
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- David Sherratt, University of Oxford, United Kingdom
Publication history
- Received: February 18, 2017
- Accepted: May 5, 2017
- Accepted Manuscript published: May 6, 2017 (version 1)
- Version of Record published: May 31, 2017 (version 2)
Copyright
© 2017, Piskadlo et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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