Large domains of heterochromatin direct the formation of short mitotic chromosome loops

Max Fitz-james, Pin Tong, Alison Pidoux, Hakan Ozadam, Liyan Yang, Sharon White, Job Dekker, Robin C. Allshire

Research output: Contribution to journalArticlepeer-review

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.
Original languageEnglish
Article numbere57212
Number of pages28
JournaleLIFE
Volume9
DOIs
Publication statusPublished - 11 Sept 2020

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