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Genes Dev
2011 Jul 15;2514:1464-9. doi: 10.1101/gad.2060311.
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The relative ratio of condensin I to II determines chromosome shapes.
Shintomi K
,
Hirano T
.
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To understand how chromosome shapes are determined by actions of condensins and cohesin, we devised a series of protocols in which their levels are precisely changed in Xenopus egg extracts. When the relative ratio of condensin I to II is forced to be smaller, embryonic chromosomes become shorter and thicker, being reminiscent of somatic chromosomes. Further depletion of condensin II unveils its contribution to axial shortening of chromosomes. Cohesin helps juxtapose sister chromatid arms by collaborating with condensin I and counteracting condensin II. Thus, chromosome shaping is achieved by an exquisite balance among condensin I and II and cohesin.
Figure 2. The relative ratio of condensin I to II determines the shape of duplicated chromosomes in Xenopus egg extracts. (A) Duplicated chromosomes were assembled in a control extract (I:II = 5:1) or a reconstituted extract (I:II = 1:1) (for details, see Supplemental Fig. S2A,B), and processed for immunofluorescence. The third panels on each row are galleries of CAP-G-labeled images of individualized chromosomes. Magnified DAPI images of the selected regions of chromosomes (indicated by the broken boxes) are shown at the right. Bars, 5 μm. (B) The lengths of chromosomes assembled in A are shown in the box plot. The middle line of each box is the median. The top and bottom lines are the third and first quartiles, and the whiskers indicate the 90th and 10th percentiles. The numbers of chromosomes measured are shown in parentheses (P = 1.2 × 10−51, t-test). (C,D) The lengths of chromosomes assembled in different extracts are compared pairwise in the box plots. A statistically significant difference was seen only between the right pair (P = 0.22, left; P = 2.2 × 10−31, right). The distribution of chromosome lengths in each condition examined in B–D is also shown in histograms (Supplemental Fig. S6).
Figure 3. Cohesin collaborates with condensins to shape chromosomes. (A) Chromosomes were assembled in extracts containing various levels of cohesin and condensin I (for details, see Supplemental Fig. S4A), and subjected to immunofluorescence analysis with anti-topoisomerase II (topo II). Blowup images of selected regions (indicated by the rectangles) are shown in the bottom row. Bar, 5 μm. The average distance between sister chromatids, together with standard deviation, is provided below each image (n = 22, 28, 21, 20, from left to right). (B) Chromosomes were assembled in a control extract (δmock), an extract depleted of cohesin (δcohesin), or Wapl (δWapl). To visualize cohesin left on these chromosomes, immunofluorescence was performed with an antibody against its SA1 subunit. Bar, 5 μm. (C) Chromosomes were assembled as described in B, and labeled with anti-CAP-G and anti-CAP-H2 antibodies. Bar, 5 μm.
Figure 4. Balancing actions of two condensins are also important for single-chromatid assembly. (A) Single chromatids (yellow arrows) and duplicated chromosomes (blue arrowheads) were assembled separately, fixed on a single slide, and subjected to immunofluorescence. Bar, 5 μm. (B) Sperm chromatin was incubated with metaphase-arrested extracts containing condensin I and II at the indicated ratios. After an 80-min incubation, chromatids were analyzed by immunofluorescence. Bar, 5 μm. (C) A model of how balancing actions of condensins and cohesin determine the shape of chromosomes is depicted in the cartoon.
Almagro,
The mitotic chromosome is an assembly of rigid elastic axes organized by structural maintenance of chromosomes (SMC) proteins and surrounded by a soft chromatin envelope.
2004, Pubmed,
Xenbase
Almagro,
The mitotic chromosome is an assembly of rigid elastic axes organized by structural maintenance of chromosomes (SMC) proteins and surrounded by a soft chromatin envelope.
2004,
Pubmed
,
Xenbase
Belmont,
A three-dimensional approach to mitotic chromosome structure: evidence for a complex hierarchical organization.
1987,
Pubmed
Gerlich,
Condensin I stabilizes chromosomes mechanically through a dynamic interaction in live cells.
2006,
Pubmed
Gerlich,
Live-cell imaging reveals a stable cohesin-chromatin interaction after but not before DNA replication.
2006,
Pubmed
Giménez-Abián,
Regulation of sister chromatid cohesion between chromosome arms.
2004,
Pubmed
Guacci,
A direct link between sister chromatid cohesion and chromosome condensation revealed through the analysis of MCD1 in S. cerevisiae.
1997,
Pubmed
Hirano,
Condensins, chromosome condensation protein complexes containing XCAP-C, XCAP-E and a Xenopus homolog of the Drosophila Barren protein.
1997,
Pubmed
,
Xenbase
Hirano,
A heterodimeric coiled-coil protein required for mitotic chromosome condensation in vitro.
1994,
Pubmed
,
Xenbase
Hirano,
Condensins: organizing and segregating the genome.
2005,
Pubmed
Hirota,
Distinct functions of condensin I and II in mitotic chromosome assembly.
2004,
Pubmed
Hudson,
Condensin: Architect of mitotic chromosomes.
2009,
Pubmed
,
Xenbase
Kireeva,
Visualization of early chromosome condensation: a hierarchical folding, axial glue model of chromosome structure.
2004,
Pubmed
Lai,
Caspase-3-mediated degradation of condensin Cap-H regulates mitotic cell death.
2011,
Pubmed
Lam,
Condensin is required for chromosome arm cohesion during mitosis.
2006,
Pubmed
Lavoie,
In vivo dissection of the chromosome condensation machinery: reversibility of condensation distinguishes contributions of condensin and cohesin.
2002,
Pubmed
Lohka,
Formation in vitro of sperm pronuclei and mitotic chromosomes induced by amphibian ooplasmic components.
1983,
Pubmed
,
Xenbase
Losada,
Identification of Xenopus SMC protein complexes required for sister chromatid cohesion.
1998,
Pubmed
,
Xenbase
Losada,
Cohesin release is required for sister chromatid resolution, but not for condensin-mediated compaction, at the onset of mitosis.
2002,
Pubmed
,
Xenbase
Losada,
Shaping the metaphase chromosome: coordination of cohesion and condensation.
2001,
Pubmed
Maeshima,
A two-step scaffolding model for mitotic chromosome assembly.
2003,
Pubmed
Marko,
Micromechanical studies of mitotic chromosomes.
2008,
Pubmed
Michaelis,
Cohesins: chromosomal proteins that prevent premature separation of sister chromatids.
1997,
Pubmed
Micheli,
Chromosome length and DNA loop size during early embryonic development of Xenopus laevis.
1993,
Pubmed
,
Xenbase
Mora-Bermúdez,
Maximal chromosome compaction occurs by axial shortening in anaphase and depends on Aurora kinase.
2007,
Pubmed
Murray,
Cell cycle extracts.
1991,
Pubmed
Nakajima,
The complete removal of cohesin from chromosome arms depends on separase.
2007,
Pubmed
Nasmyth,
Cohesin: its roles and mechanisms.
2009,
Pubmed
Onn,
Sister chromatid cohesion: a simple concept with a complex reality.
2008,
Pubmed
Ono,
Differential contributions of condensin I and condensin II to mitotic chromosome architecture in vertebrate cells.
2003,
Pubmed
,
Xenbase
Ono,
Spatial and temporal regulation of Condensins I and II in mitotic chromosome assembly in human cells.
2004,
Pubmed
Peters,
The cohesin complex and its roles in chromosome biology.
2008,
Pubmed
Shintomi,
Releasing cohesin from chromosome arms in early mitosis: opposing actions of Wapl-Pds5 and Sgo1.
2009,
Pubmed
,
Xenbase
Swedlow,
The making of the mitotic chromosome: modern insights into classical questions.
2003,
Pubmed
Waizenegger,
Two distinct pathways remove mammalian cohesin from chromosome arms in prophase and from centromeres in anaphase.
2000,
Pubmed
,
Xenbase
