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Contrasting roles of condensin I and condensin II in mitotic chromosome formation
journal contribution
posted on 2023-05-18, 19:27 authored by Green, LC, Kalitsis, P, Chang, TM, Cipetic, M, Kim, H, Owen MarshallOwen Marshall, Turnbull, L, Whitchurch, CB, Vagnarelli, P, Samejima, K, Earnshaw, WC, Choo, KHA, Hudson, DFIn vertebrates, two condensin complexes exist, condensin I and condensin II, which have differing but unresolved roles in organizing mitotic chromosomes. To dissect accurately the role of each complex in mitosis, we have made and studied the first vertebrate conditional knockouts of the genes encoding condensin I subunit CAP-H and condensin II subunit CAP-D3 in chicken DT40 cells. Live-cell imaging reveals highly distinct segregation defects. CAP-D3 (condensin II) knockout results in masses of chromatin-containing anaphase bridges. CAP-H (condensin I)-knockout anaphases have a more subtle defect, with chromatids showing fine chromatin fibres that are associated with failure of cytokinesis and cell death. Super-resolution microscopy reveals that condensin-I-depleted mitotic chromosomes are wider and shorter, with a diffuse chromosome scaffold, whereas condensin-II-depleted chromosomes retain a more defined scaffold, with chromosomes more stretched and seemingly lacking in axial rigidity. We conclude that condensin II is required primarily to provide rigidity by establishing an initial chromosome axis around which condensin I can arrange loops of chromatin.
History
Publication title
Journal of Cell ScienceVolume
125Issue
6Pagination
1591-1604ISSN
0021-9533Department/School
Menzies Institute for Medical ResearchPublisher
Company Of Biologists LtdPlace of publication
Bidder Building Cambridge Commercial Park Cowley Rd, Cambridge, England, Cambs, Cb4 4DlRepository Status
- Restricted