Condensin and Repo-Man–PP1 co-operate in the regulation of chromosome architecture during mitosis

Vagnarelli, Paola; Hudson, Damien F.; Ribeiro, Sylvie; Trinkle-Mulcahy, Laura; Spence, Jennifer M.; Lai, Fang; Farr, Carol L.; Lamond, Angus I.; Earnshaw, William C.

doi:10.1038/ncb1475

Cited by 205 publications

(268 citation statements)

References 31 publications

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“…The SMC2 conditional knockout cell line and SMC2:CENP-H:GFP_H2B: mRFP were cultured as previously described (Hudson et al, 2003;Vagnarelli et al, 2006). The SMC2 conditional knockout cell line containing a human X-derived minichromosome was described previously (Vagnarelli et al, 2006).…”

Section: Cell Culture Transfections and Drug Treatmentsmentioning

confidence: 99%

“…The SMC2 conditional knockout cell line containing a human X-derived minichromosome was described previously (Vagnarelli et al, 2006).…”

Section: Cell Culture Transfections and Drug Treatmentsmentioning

confidence: 99%

“…In controls, a LacO array integrated on the arm of a macro-chromosome (Figure 4a, ARM) maintained a constant relative distance between sister chromatids during metaphase in cells lacking condensin (Figure 4c; Supplementary Figure 3 , b and d, and Supplementary Movies 11 and 12). This distance was larger than that in cells expressing SMC2 because, unlike inner centromeric chromatin, arm chromatin is 40% less compact in SMC2 OFF cells (Hudson et al, 2003;Vagnarelli et al, 2006).To begin to address the underlying mechanism by which condensin regulates centromere stiffness, we asked whether SMC2 ATPase activity is required for normal behavior of kinetochores under tension at metaphase. One strength of the DT40 cell conditional knockout system is that it is possible to perform complementation studies under conditions where the wild-type protein is essentially undetectable.…”

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confidence: 99%

“…Cytochalasin D (Sigma) at 6 g/ml was added 5 h before fixation in order to maintain the products of each segregation event within a common cytoplasm. Fixed cells were subjected to FISH with an X-specific ␣-satellite probe as previously described (Vagnarelli et al, 2006). …”

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confidence: 99%

“…Fixed cells were subjected to FISH with an X-specific ␣-satellite probe as previously described (Vagnarelli et al, 2006).…”

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confidence: 99%

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Condensin Regulates the Stiffness of Vertebrate Centromeres

Ribeiro

Gatlin

Yang

et al. 2009

MBoC

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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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Section: Cell Culture Transfections and Drug Treatmentsmentioning

confidence: 99%

“…The SMC2 conditional knockout cell line containing a human X-derived minichromosome was described previously (Vagnarelli et al, 2006).…”

Section: Cell Culture Transfections and Drug Treatmentsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…Fixed cells were subjected to FISH with an X-specific ␣-satellite probe as previously described (Vagnarelli et al, 2006).…”

mentioning

confidence: 99%

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Condensin Regulates the Stiffness of Vertebrate Centromeres

Ribeiro

Gatlin

Yang

et al. 2009

MBoC

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137

147

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Getting out of mitosis: spatial and temporal control of mitotic exit and cytokinesis by PP1 and PP2A

2019

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Here, we will review the evidence showing that mitotic exit is initiated by regulated proteolysis and then driven by the PPP family of phosphoserine/threonine phosphatases. Rapid APC/CCDC20 and ubiquitin‐dependent proteolysis of cyclin B and securin initiates sister chromatid separation, the first step of mitotic exit. Because proteolysis of Aurora and Polo family kinases dependent on APC/CCDH1 is relatively slow, this creates a new regulatory state, anaphase, different to G2 and M‐phase. We will discuss how the CDK1‐counteracting phosphatases PP1 and PP2A‐B55, together with Aurora and Polo kinases, contribute to the temporal regulation and order of events in the different stages of mitotic exit from anaphase to cytokinesis. For PP2A‐B55, these timing properties are created by the ENSA‐dependent inhibitory pathway and differential recognition of phosphoserine and phosphothreonine. Finally, we will discuss how Aurora B and PP2A‐B56 are needed for the spatial regulation of anaphase spindle formation and how APC/C‐dependent destruction of PLK1 acts as a timer for abscission, the final event of cytokinesis.

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Chromosomes and Chromatin

Paulson

Vagnarelli

2011

Encyclopedia of Life Sciences

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Chromosomes are structures within the nuclei of eukaryotic cells that contain deoxyribonucleic acid (DNA) combined with proteins. Chromatin refers to the material of the chromosomes – DNA plus proteins. Before DNA replication, each chromosome contains a single, very long DNA molecule that basically runs from one end of the chromosome to the other. Core histone proteins package segments of this DNA molecule into nucleosomes, and linker histones further compact the resulting ‘string of beads’ into a 30‐nm chromatin fibre. In mitotic chromosomes, scaffold proteins fold the chromatin fibre into loops along its length. Chromosomes are very dynamic structures and take several forms, but the basic organisation is always related to the structure of mitotic chromosomes. The location of chromosomes in the nucleus, the nature of the loops and modifications to the chromatin fibre are thought to be important in determining which DNA sequences are made available for transcription and other processes. Key Concepts: In eukaryotic cells, genes are located in chromosomes in the cell nucleus. Before the DNA has been replicated, a chromosome consists of a single very long DNA double helix that is highly coiled and folded by proteins. Five major types of histone proteins, all of them highly basic, neutralise much of the DNA's negative charge and package the DNA into nucleosomes and 30‐nm fibres. The N ‐terminal tails of core histones are intrinsically disordered, allowing them to interact with many other proteins and undergo various posttranslational modifications. Transcriptional activation of genes, or readiness for transcriptional activation, is associated with histone acetylation, and inactivation is generally associated with histone methylation. In mitotic chromosomes, the chromatin fibre is folded into loops by attachment to a scaffold of nonhistone proteins. Mitotic chromosome condensation appears to involve two components: compaction of the chromatin at the onset of mitosis, which involves phosphorylation of chromosomal proteins, and establishment of a robust architecture that can withstand spindle forces, which involves condensin. The various chromosome forms that are seen throughout the cell cycle or the life cycle of the organism have closely related structures. A chromosome during interphase retains some aspects of the structure it had during mitosis and is confined to a distinct ‘territory’ within the interphase nucleus. Chromosome banding and chromosome painting are medically important for detecting chromosome abnormalities such as breaks, fusions, translocations and aneuploidy and can be used to track chromosomal rearrangements that have occurred during evolution.

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Condensin and Repo-Man–PP1 co-operate in the regulation of chromosome architecture during mitosis

Cited by 205 publications

References 31 publications

Condensin Regulates the Stiffness of Vertebrate Centromeres

Condensin Regulates the Stiffness of Vertebrate Centromeres

Getting out of mitosis: spatial and temporal control of mitotic exit and cytokinesis by PP1 and PP2A

Chromosomes and Chromatin

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