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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, DF
In 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 Science

Volume

125

Issue

6

Pagination

1591-1604

ISSN

0021-9533

Department/School

Menzies Institute for Medical Research

Publisher

Company Of Biologists Ltd

Place of publication

Bidder Building Cambridge Commercial Park Cowley Rd, Cambridge, England, Cambs, Cb4 4Dl

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the health sciences

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