A postprophase topoisomerase II-dependent chromatid core separation step in the formation of metaphase chromosomes.

Giménez-Abián, Juan F.; Clarke, Duncan J.; Mullinger, Ann M.; Downes, C. Stephen; Johnson, Robert T.

doi:10.1083/jcb.131.1.7

Cited by 102 publications

(99 citation statements)

References 52 publications

(69 reference statements)

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“…Indeed, in higher eukaryotes, Topoisomerase II is an essential component of the mitotic scaffold and is clearly required for linear chromosome compaction. However, in the absence of Topo II activity, nucleoli are able to reorganize into discrete nucleolar organizer regions that are not different in appearance from those in properly condensed chromosomes (Gimenez-Abian et al, 1995). Thus we propose that Topo II is required for linear chromosome compaction in budding yeast as it is in other eukaryotes.…”

Section: Discussionmentioning

confidence: 79%

“…In higher eukaryotes, the process of condensing chromosomes before anaphase requires a protein scaffold comprised of at least condensin and topoisomerase II (Earnshaw et al, 1985;Gasser et al, 1986;Adachi et al, 1991;Saitoh et al, 1994;Gimenez-Abian et al, 1995;Hirano et al, 1997;Maeshima and Laemmli, 2003). Condensin is a five-subunit complex that was first identified in Xenopus egg extracts (Hirano, 2005).…”

Section: Introductionmentioning

confidence: 99%

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In Vivo Analysis of Chromosome Condensation inSaccharomyces cerevisiae

Vas

Andrews

Matesky

et al. 2007

MBoC

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Although chromosome condensation in the yeast Saccharomyces cerevisiae has been widely studied, visualization of this process in vivo has not been achieved. Using Lac operator sequences integrated at two loci on the right arm of chromosome IV and a Lac repressor-GFP fusion protein, we were able to visualize linear condensation of this chromosome arm during G2/M phase. As previously determined in fixed cells, condensation in yeast required the condensin complex. Not seen after fixation of cells, we found that topoisomerase II is required for linear condensation. Further analysis of perturbed mitoses unexpectedly revealed that condensation is a transient state that occurs before anaphase in budding yeast. Blocking anaphase progression by activation of the spindle assembly checkpoint caused a loss of condensation that was dependent on Mad2, followed by a delayed loss of cohesion between sister chromatids. Release of cells from spindle checkpoint arrest resulted in recondensation before anaphase onset. The loss of condensation in preanaphase-arrested cells was abrogated by overproduction of the aurora B kinase, Ipl1, whereas in ipl1-321 mutant cells condensation was prematurely lost in anaphase/telophase. In vivo analysis of chromosome condensation has therefore revealed unsuspected relationships between higher order chromatin structure and cell cycle control. INTRODUCTIONAccurate chromosome segregation during mitosis is facilitated by the resolution of chromosomes into compact structures. From the level of the nucleosome, chromatin undergoes several changes in organization (Earnshaw, 1988;Filipski et al., 1990). A scaffold of proteins form an axis along which solenoidal chromatin loops are folded into rosettes, which then coalesce to form a sausage-shaped chromonema Marsden and Laemmli, 1979; Johnson, 1979, 1980;Earnshaw and Laemmli, 1983;Earnshaw, 1988). The metaphase chromosome consists of a folded or coiled chromonema (Manton, 1950). In a more recent model of chromosome organization, chromatin is folded into fibers around the central axis, which acts as a "glue" (Kireeva et al., 2004). In both of these models, the protein scaffold is proposed to condense linearly during mitosis.The mitotic scaffold was first observed in histone-depleted mammalian chromosomes and components of this protein scaffold have been of considerable interest (Adolphs et al., 1977;Paulson and Laemmli, 1977). In higher eukaryotes, the process of condensing chromosomes before anaphase requires a protein scaffold comprised of at least condensin and topoisomerase II (Earnshaw et al., 1985;Gasser et al., 1986;Adachi et al., 1991;Saitoh et al., 1994;Gimenez-Abian et al., 1995;Hirano et al., 1997;Maeshima and Laemmli, 2003). Condensin is a five-subunit complex that was first identified in Xenopus egg extracts (Hirano, 2005). Homologues of mitotic scaffold proteins are present in all eukaryotes (reviewed in Hirano, 2005). In the budding yeast Saccharomyces cerevisiae, homologues of the condensin complex, encoded by SMC2, SMC4, YCG1, YCS4, and BRN...

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Section: Discussionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

In Vivo Analysis of Chromosome Condensation inSaccharomyces cerevisiae

Vas

Andrews

Matesky

et al. 2007

MBoC

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“…In vitro studies of chromosome condensation in mitotic extracts (Newport and Spann, 1987;Adachi et al, 1991;Hirano and Mitchison, 1991, 1993), in which topoII is immunodepleted or inactivated by inhibitors, showed varying requirements for topoII. In the absence of suitable topoII mutants, in vivo studies in higher eukaryotes have made use of topoII inhibitors (Andoh et al, 1993;Downes et al, 1994;Gorbsky, 1994;Ishida et al, 1994;Gimenez-Abian et al, 1995;Andreassen et al, 1997;Gimenez-Abian et al, 2000) or RNA interference (Chang et al, 2003;Sakaguchi and Kikuchi, 2004). Such studies mostly support a role for topoII in chromosome condensation, but again, condensation was impaired to varying degrees, and in some cases (Andreassen et al, 1997;Chang et al, 2003;Sakaguchi and Kikuchi, 2004) impairment was surprisingly mild or absent.…”

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confidence: 99%

Construction, Characterization, and Complementation of a Conditional-Lethal DNA Topoisomerase IIα Mutant Human Cell Line

Carpenter

Porter

2004

MBoC

133

175

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DNA Topoisomerase II␣ (topoII␣) is a DNA decatenating enzyme, abundant constituent of mammalian mitotic chromosomes, and target of numerous antitumor drugs, but its exact role in chromosome structure and dynamics is unclear. In a powerful new approach to this important problem, with significant advantages over the use of topoII inhibitors or RNA interference, we have generated and characterized a human cell line (HTETOP) in which >99.5% topoII␣ expression can be silenced in all cells by the addition of tetracycline. TopoII␣-depleted HTETOP cells enter mitosis and undergo chromosome condensation, albeit with delayed kinetics, but normal anaphases and cytokineses are completely prevented, and all cells die, some becoming polyploid in the process. Cells can be rescued by expression of topoII␣ fused to green fluorescent protein (GFP), even when certain phosphorylation sites have been mutated, but not when the catalytic residue Y805 is mutated. Thus, in addition to validating GFP-tagged topoII␣ as an indicator for endogenous topoII␣ dynamics, our analyses provide new evidence that topoII␣ plays a largely redundant role in chromosome condensation, but an essential catalytic role in chromosome segregation that cannot be complemented by topoII␤ and does not require phosphorylation at serine residues 1106, 1247, 1354, or 1393. INTRODUCTIONType II topoisomerases are ubiquitous, highly conserved proteins that catalyze the passage of one DNA duplex through another, creating a transient double-strand break (DSB) in the latter (Watt and Hickson, 1994;Wang, 2002). Studies in a variety of systems indicate that topoII is essential for cellular viability and that it plays a key role in chromosome segregation. Thus, the abnormal cell divisions seen in yeast top2 mutants (Holm et al., 1985;Uemura and Yanagida, 1986), and in vertebrate cells treated with topoII inhibitors (Downes et al., 1991;Ishida et al., 1991Ishida et al., , 1994Haraguchi et al., 2000) are consistent with the unique ability of topoII to resolve the sister chromatids catenations generated when DNA replication forks meet (Wang, 2002). TopoII has been implicated in mammalian centromere function (Floridia et al., 2000;Spence et al., 2002), and it has been suggested that topoII in yeast may play a role in centromeric chromatin structure (Bachant et al., 2002). Further work is required to understand the relationship between any such structural role, topoII-mediated chromatid decatenation, and the role of the cohesin complex (Nasmyth, 2002) in maintaining sister chromatid cohesion until anaphase (Bernard and Allshire, 2002).TopoII also has been implicated in DNA recombination, replication, transcription, and chromosome condensation (Watt and Hickson, 1994;Wang, 2002). Of these, chromosome condensation is the only process in which topoII is widely reported to play an essential role (Koshland and Strunnikov, 1996;Losada and Hirano, 2001;Swedlow and Hirano, 2003), but the data are equivocal. Genetic analyses suggest that topoII is required for chromosome condensation in Sc...

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“…63,64,68,69 Incubation of mammalian cells with ICRF-193 was shown to induce cohesive chromatids in prophase, intertwined daughter chromatids in metaphase and chromosome bridges in anaphase. [70][71][72] Once cells have entered mitosis, topoisomerase II catalytic activity is required to segregate sister chromatids at the metaphase/anaphase transition. Topoisomerase II is also required at this step in yeast.…”

Section: Introductionmentioning

confidence: 99%

Degradation of ATM-Independent Decatenation Checkpoint Function in Human Cells is Secondary to Inactivation of p53 and Correlated with Chromosomal Destabilization

Campbell¹,

Simpson²,

Deming³

et al. 2002

Cell Cycle

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DNA topoisomerase II is required in the cell cycle to decatenate intertwined daughter chromatids prior to mitosis. To study the mechanisms that cells use to accomplish timely chromatid decatenation, the activity of a catenation-responsive checkpoint was monitored in human skin fibroblasts with inherited or acquired defects in the DNA damage G2 checkpoint. G2 delay was quantified shortly after a brief incubation with ICRF-193, which blocks the ability of topoisomerase II to decatenate chromatids, or treatment with ionizing radiation (IR), which damages DNA. Both treatments induced G2 delay in normal human fibroblasts. Ataxia telangiectasia fibroblasts with defective G2 checkpoint response to IR displayed normal G2 delay after treatment with ICRF-193, demonstrating that ATM kinase was not required for signaling when chromatid decatenation was blocked. The G2 delay induced by ICRF-193 was reversed by caffeine, indicating that active checkpoint signaling was involved. ICRF-193-induced G2 delay also was independent of p53 function, being evident in cells expressing HPV16E6 to inactivate p53. However, as fibroblasts expressing HPV16E6 aged in culture, they lost the ability to delay entry to mitosis, both after DNA damage and when decatenation was blocked. This age-related loss of G2 delay in response to ICRF-193 and IR in E6-expressing cells was blocked by induction of telomerase. Expression of telomerase also prevented chromosomal destabilization in aging E6-expressing cells. These observations lead to a new model of genetic instability, in which attenuation of G2 decatenatory checkpoint function permits cells to enter mitosis with insufficiently decatenated chromatids, leading to aneuploidy and polyploidy.

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A postprophase topoisomerase II-dependent chromatid core separation step in the formation of metaphase chromosomes.

Cited by 102 publications

References 52 publications

In Vivo Analysis of Chromosome Condensation inSaccharomyces cerevisiae

In Vivo Analysis of Chromosome Condensation inSaccharomyces cerevisiae

Construction, Characterization, and Complementation of a Conditional-Lethal DNA Topoisomerase IIα Mutant Human Cell Line

Degradation of ATM-Independent Decatenation Checkpoint Function in Human Cells is Secondary to Inactivation of p53 and Correlated with Chromosomal Destabilization

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