title: Contrasting roles of condensin I and condensin II in mitotic chromosome formation.
abstract: 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.
authors.affiliation: Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria 3052,  Australia.
authors.forename: Lydia C
authors.initials: LC
authors.lastname: Green
authors.forename: Paul
authors.initials: P
authors.lastname: Kalitsis
authors.forename: Tsz M
authors.initials: TM
authors.lastname: Chang
authors.forename: Miri
authors.initials: M
authors.lastname: Cipetic
authors.forename: Ji Hun
authors.initials: JH
authors.lastname: Kim
authors.forename: Owen
authors.initials: O
authors.lastname: Marshall
authors.forename: Lynne
authors.initials: L
authors.lastname: Turnbull
authors.forename: Cynthia B
authors.initials: CB
authors.lastname: Whitchurch
authors.forename: Paola
authors.initials: P
authors.lastname: Vagnarelli
authors.forename: Kumiko
authors.initials: K
authors.lastname: Samejima
authors.forename: William C
authors.initials: WC
authors.lastname: Earnshaw
authors.forename: K H Andy
authors.initials: KH
authors.lastname: Choo
authors.forename: Damien F
authors.initials: DF
authors.lastname: Hudson
mesh_terms: D000251:Adenosine Triphosphatases / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D000818:Animals; D045744:Cell Line, Tumor; D002645:Chickens; D002875:Chromosomes / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D055786:Gene Knockout Techniques / Q000379:methods; D008938:Mitosis / Q000235:genetics*; D046912:Multiprotein Complexes / Q000172:deficiency / Q000235:genetics / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; C108312:condensin complexes; D000251:Adenosine Triphosphatases