1. Genome folding principles uncovered in condensin-depleted mitotic chromosomes.
- Author
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Zhao H, Lin Y, Lin E, Liu F, Shu L, Jing D, Wang B, Wang M, Shan F, Zhang L, Lam JC, Midla SC, Giardine BM, Keller CA, Hardison RC, Blobel GA, and Zhang H
- Subjects
- Humans, Interphase genetics, Chromosomes genetics, Chromobox Protein Homolog 5, Chromatin metabolism, Chromatin genetics, Adenosine Triphosphatases genetics, Adenosine Triphosphatases metabolism, Multiprotein Complexes genetics, Multiprotein Complexes metabolism, DNA-Binding Proteins metabolism, DNA-Binding Proteins genetics, Mitosis genetics, Chromosomal Proteins, Non-Histone metabolism, Chromosomal Proteins, Non-Histone genetics, Heterochromatin metabolism, Heterochromatin genetics
- Abstract
During mitosis, condensin activity is thought to interfere with interphase chromatin structures. To investigate genome folding principles in the absence of chromatin loop extrusion, we codepleted condensin I and condensin II, which triggered mitotic chromosome compartmentalization in ways similar to that in interphase. However, two distinct euchromatic compartments, indistinguishable in interphase, emerged upon condensin loss with different interaction preferences and dependencies on H3K27ac. Constitutive heterochromatin gradually self-aggregated and cocompartmentalized with facultative heterochromatin, contrasting with their separation during interphase. Notably, some cis-regulatory element contacts became apparent even in the absence of CTCF/cohesin-mediated structures. Heterochromatin protein 1 (HP1) proteins, which are thought to partition constitutive heterochromatin, were absent from mitotic chromosomes, suggesting, surprisingly, that constitutive heterochromatin can self-aggregate without HP1. Indeed, in cells traversing from M to G1 phase in the combined absence of HP1α, HP1β and HP1γ, constitutive heterochromatin compartments are normally re-established. In sum, condensin-deficient mitotic chromosomes illuminate forces of genome compartmentalization not identified in interphase cells., (© 2024. The Author(s), under exclusive licence to Springer Nature America, Inc.)
- Published
- 2024
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