Contrasting roles of condensin I and condensin II in mitotic chromosome formation

L.C. Green, P. Kalitsis, T.M. Chang, M. Cipetic, J.H. Kim, O. Marshall, K.H.A. Choo, D.F. Hudson, L. Turnbull, C.B. Whitchurch, P. Vagnarelli, K. Samejima, W.C. Earnshaw

Research output: Contribution to journalArticlepeer-review


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 chromatincontaining 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-Idepleted 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.
Original languageEnglish
Pages (from-to)1591-1604
Number of pages14
JournalJournal of Cell Science
Issue number6
Publication statusPublished - 15 Mar 2012


  • Condensin
  • Chromosome structure


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