Large domains of heterochromatin direct the formation of short mitotic chromosome loops
- University of Edinburgh, United Kingdom
- Wellcome Trust Centre for Cell Biology, United Kingdom
- University of Massachusetts Medical School, United States
Abstract
During mitosis chromosomes reorganise into highly compact, rod-shaped forms, thought to consist of consecutive chromatin loops around a central protein scaffold. Condensin complexes are involved in chromatin compaction, but the contribution of other chromatin proteins, DNA sequence and histone modifications is less understood. A large region of fission yeast DNA inserted into a mouse chromosome was previously observed to adopt a mitotic organisation distinct from that of surrounding mouse DNA. Here we show that a similar distinct structure is common to a large subset of insertion events in both mouse and human cells and is coincident with the presence of high levels of heterochromatic H3 lysine 9 trimethylation (H3K9me3). Hi-C and microscopy indicate that the heterochromatinised fission yeast DNA is organised into smaller chromatin loops than flanking euchromatic mouse chromatin. We conclude that heterochromatin alters chromatin loop size, thus contributing to the distinct appearance of heterochromatin on mitotic chromosomes.
Data availability
DNA sequencing and nanopore data were uploaded to the Sequence Read Archive with project ID PRJNA629899. Hi-C data was uploaded to GEO with accession ID GSE149677.
Article and author information
Author details
Maximilian H. Fitz-James
Funding
Wellcome Trust (Wellcome 4 year PhD studentship,102336/Z/13/Z)
- Maximilian H. Fitz-James
Wellcome Trust (Principal Research Fellowship,095021)
- Robin Allshire
Wellcome Trust (Principal Research Fellowship,200885)
- Robin Allshire
Wellcome Trust (Wellcome Centre for Cell Biology Core grant,203149)
- Maximilian H. Fitz-James
- Pin Tong
- Alison L Pidoux
- Sharon A. White
- Robin Allshire
National Human Genome Research Institute (HG003143)
- Hakan Ozadam
- Liyan Yang
- Job Dekker
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2020, Fitz-James 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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