The condensin complex is required for proper spindle assembly and chromosome segregation in <i>Xenopus</i> egg extracts

Wignall, Sarah M.; Deehan, Renée; Maresca, Thomas J.; Heald, Rebecca

doi:10.1083/jcb.200303185

Cited by 54 publications

(61 citation statements)

References 48 publications

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“…4 Similar results were obtained under a more physiological condition where chromosomes with sister chromatids were assembled after a single round of DNA replication. 13,14 These results show that condensin is required for both the individualization and shaping steps. Addition of the same antibody to the extract after the assembly reaction was completed led to progressive disruption of the rod-shaped chromosomes and converted them into randomly coiled, chromatin balls.…”

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confidence: 80%

Chromosome Shaping by Two Condensins

Hirano¹

2004

Cell Cycle

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It remains a big challenge in modern cell biology to determine the mechanism by which a discrete set of rod-shaped chromosomes is assembled from an amorphous mass of interphase chromatin. Recent studies start to shed new lights on how this process is actively supported by a class of multiprotein complexes called condensins. In vertebrate cells, two different condensin complexes make distinct mechanistic contributions to determining the shape and integrity of mitotic chromosomes.

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confidence: 80%

Chromosome Shaping by Two Condensins

Hirano¹

2004

Cell Cycle

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“…In human cells, RNAi for condensin caused aberrations in CENP-E and CREST signal geometry in one study (Ono et al, 2004) but no evident distortion of CENP-A signals in another (Gerlich et al, 2006). In Xenopus egg extracts, immunodepletion of condensin caused abnormal CENP-E localization (Wignall et al, 2003), and in Drosophila condensin RNAi, CID (the CENP-A homologue) was found to be distorted in metaphase (Jäger et al, 2005). Distortion of the kinetochore was also observed in the holocentric chromosomes of Caenorhabditis elegans after condensin RNAi (Hagstrom et al, 2002).…”

Section: Kinetochores Appear Structurally and Functionally Normal In mentioning

confidence: 99%

Condensin Regulates the Stiffness of Vertebrate Centromeres

Ribeiro

Gatlin

Yang

et al. 2009

MBoC

134

147

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When chromosomes are aligned and bioriented at metaphase, the elastic stretch of centromeric chromatin opposes pulling forces exerted on sister kinetochores by the mitotic spindle. Here we show that condensin ATPase activity is an important regulator of centromere stiffness and function. Condensin depletion decreases the stiffness of centromeric chromatin by 50% when pulling forces are applied to kinetochores. However, condensin is dispensable for the normal level of compaction (rest length) of centromeres, which probably depends on other factors that control higher-order chromatin folding. Kinetochores also do not require condensin for their structure or motility. Loss of stiffness caused by condensindepletion produces abnormal uncoordinated sister kinetochore movements, leads to an increase in Mad2(؉) kinetochores near the metaphase plate and delays anaphase onset. INTRODUCTIONCentromeric chromatin is a special region of chromosomes that has important mechanical and signaling functions in mitosis (Pidoux and Allshire, 2005;Ekwall, 2007;Cheeseman and Desai, 2008;Vagnarelli et al., 2008). In metaphase, pulling forces generated by interactions between spindle microtubules (MTs) and kinetochores are opposed by tension produced by centromeric chromatin stretch. Centromere and kinetochore tension and stretch are important for maintaining chromosome alignment (McIntosh et al., 2002), stabilizing kinetochore microtubule (kMT) attachments (Nicklas and Koch, 1969), spindle checkpoint signaling (Musacchio and Salmon, 2007;McEwen and Dong, 2009), and also for the back-to-back orientation of sister kinetochores (Loncarek et al., 2007). At least three independent factors have roles in the establishment of centromeric tension in metaphase: sister chromatid cohesion (Yeh et al., 2008), the elastic properties of chromatin (Houchmandzadeh et al., 1997;Almagro et al., 2004;Marko, 2008), and the higher order structure of the centromeric chromatin.Condensin is important for the architecture of mitotic chromosome arms (Coelho et al., 2003;Hudson et al., 2003;Hirota et al., 2004;Hirano, 2006), but it also localizes to centromeres (Saitoh et al., 1994;Gerlich et al., 2006), where condensin I, but not condensin II was reported to have a role in stabilizing the structure (Gerlich et al., 2006). It has recently been suggested that condensin could have a role in regulating the elastic behavior of centromeric chromatin. One study found that condensin I-depleted Drosophila chromosomes were unable to align at a metaphase plate, had distorted kinetochore structures, and lost elasticity of their centromeric chromatin (Oliveira et al., 2005). However a similar study in human cells reported that although loss of condensin I caused kinetochores to undergo abnormal movements, these movements were bidirectional (e.g., reversible; Gerlich et al., 2006).Even after the publication of those results, the regulation and functional significance of centromere stretch remained unknown. An elegant study in budding yeast went on to find that chromatin struct...

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“…A study to examine the role of condensin after metaphase was performed by adding antibodies against condensin to Xenopus in vitro extracts immediately after the addition of Ca 2+ , for the release from metaphase, and a chromosome non-disjunction phenotype was observed (Wignall et al, 2003). Similarly, antibody blocking of condensin was performed in frog egg extracts after condensation, and a resulting deformation of mitotic chromosomes found (Hirano and Mitchison, 1994).…”

Section: Introductionmentioning

confidence: 99%

Condensin phosphorylated by the Aurora-B-like kinase Ark1 is continuously required until telophase in a mode distinct from Top2

Nakazawa

Mehrotra

Ebe

et al. 2011

Journal of Cell Science

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SummaryCondensin is a conserved protein complex that functions in chromosome condensation and segregation. It has not been previously unequivocally determined whether condensin is required throughout mitosis. Here, we examined whether Schizosaccharomyces pombe condensin continuously acts on chromosomes during mitosis and compared its role with that of DNA topoisomerase II (Top2). Using double mutants containing a temperature-sensitive allele of the condensin SMC2 subunit cut14 (cut14-208) or of top2, together with the cold-sensitive nda3-KM311 mutation (in -tubulin), temperature-shift experiments were performed. These experiments allowed inactivation of condensin or Top2 at various stages throughout mitosis, even after late anaphase. The results established that mitotic chromosomes require condensin and Top2 throughout mitosis, even in telophase. We then showed that the Cnd2 subunit of condensin (also known as Barren) is the target subunit of Aurora-B-like kinase Ark1 and that Ark1-mediated phosphorylation of Cnd2 occurred throughout mitosis. The phosphorylation sites in Cnd2 were determined by mass spectrometry, and alanine and glutamate residue replacement mutant constructs for these sites were constructed. Alanine substitution mutants of Cnd2, which mimic the unphosphorylated protein, exhibited broad mitotic defects, including at telophase, and overexpression of these constructs caused a severe dominantnegative effect. By contrast, glutamate substitution mutants, which mimic the phosphorylated protein, alleviated the segregation defect in Ark1-inhibited cells. In telophase, the condensin subunits in cut14-208 mutant accumulated in lumps that contained telomeric DNA and proteins that failed to segregate. Condensin might thus serve to keep the segregated chromosomes apart during telophase.

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The condensin complex is required for proper spindle assembly and chromosome segregation in Xenopus egg extracts

Cited by 54 publications

References 48 publications

Chromosome Shaping by Two Condensins

Chromosome Shaping by Two Condensins

Condensin Regulates the Stiffness of Vertebrate Centromeres

Condensin phosphorylated by the Aurora-B-like kinase Ark1 is continuously required until telophase in a mode distinct from Top2

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