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Andersen, Claus Lindbjerg; Wandall, Annelise; Kjeldsen, Eigil; Mielke, Christian; Koch, Jørn

doi:10.1023/a:1016571825025

Cited by 31 publications

(27 citation statements)

References 27 publications

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“…What is the nature of such catenations and why do they seem to affect only a subset of chromosomes? Given the persistent association of sister centromeres after chromatid arms have separated (Losada and Hirano, 2001;Bernard and Allshire, 2002), and the known accumulation of topoII␣ protein (Rattner et al, 1996;Sumner, 1996) and topoII activity (Floridia et al, 2000;Andersen et al, 2002;Spence et al, 2002;Agostinho et al, 2004) at centromeres, one may reasonably speculate that centromeric catenations are uniquely resolved by topoII␣ and persist after anaphase onset in topoII␣-depleted cells. In the absence of cohesin-dependent centromeric cohesion, poleward forces might then be sufficient to allow near normal separation of sister kinetochores, at the expense of severe chromosomal distortions and DNA damage, resulting in the dissociation of many, but not all, sister chromosomes.…”

Section: Essential Role For Topoii␣ Activity In Chromosome Segregationmentioning

confidence: 99%

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

Carpenter

Porter

2004

MBoC

136

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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Section: Essential Role For Topoii␣ Activity In Chromosome Segregationmentioning

confidence: 99%

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

Carpenter

Porter

2004

MBoC

136

175

View full text Add to dashboard Cite

show abstract

“…During metaphase, topoisomerase-II accumulates specifically at active centromeres, where it is required for proper kinetochore͞centromere structure and to decatenate sister chromatids before segregation (19)(20)(21)(22)(23). Decatenation is a three-step process that involves double-stranded DNA cleavage, passage of one strand of the duplex through the break, and religation to repair the lesion.…”

mentioning

confidence: 99%

Evidence on the chromosomal location of centromeric DNA in Plasmodium falciparum from etoposide-mediated topoisomerase-II cleavage

Kelly

McRobert

Baker

2006

Proc. Natl. Acad. Sci. U.S.A.

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Centromeres are the chromosomal loci that facilitate segregation, and, in most eukaryotes, they encompass extensive regions of genomic DNA. Topoisomerase-II has been identified as a crucial regulator of segregation in a wide range of organisms and exhibits premitotic accumulation at centromeres. Consistent with this property, treatment of cells with the topoisomerase-II inhibitor etoposide promotes chromosomal cleavage at sites within centromeric DNA. In the case of the human malaria parasite Plasmodium falciparum, despite a completed genome sequence, there are no experimental data on the nature of centromeres. To address this issue, we have used etoposide-mediated topoisomerase-II cleavage as a biochemical marker to map centromeric DNA on all 14 parasite chromosomes. We find that topoisomerase-II activity is concentrated at single chromosomal loci and that cleavage sites extend over Ϸ10 kb. A shared feature of these topoisomerase-II cleavage sites is the presence of an extremely AT-rich (Ϸ97%) domain with a strictly defined size limit of 2.3-2.5 kb. Repetitive arrays identified within the domains do not display interchromosomal conservation in terms of length, copy number, or sequence. These unusual properties suggest that P. falciparum chromosomes contain a class of ''regional'' centromere distinct from those described in other eukaryotes, including the human host.chromosome ͉ malaria ͉ segregation

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“…Mapping of deletion chromosomes has delimited the functional centromere region of the human X chromosome to the higher-order alpha-satellite array, DXZ1 (26). Topoisomerase II cleavage activity is found at the active centromere but not the inactive centromere of dicentric chromosomes (28) and has been localized within higher-order arrays of the X (29) and Y (30) chromosome. Chromatin immunoprecipitation (31) and fiber-FISH (32) studies have found higher-order alpha-satellite sequences associated with essential kinetochore proteins.…”

mentioning

confidence: 99%

Progressive proximal expansion of the primate X chromosome centromere

Schueler

Dunn²,

Bird³

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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Previous studies of the pericentromeric region of the human X chromosome short arm (Xp) revealed an age gradient from ancient DNA that contains expressed genes to recent human-specific DNA at the functional centromere. We analyzed the finished sequence of this human genomic region to investigate its evolutionary history. Phylogenetic analysis of >1,500 alpha-satellite monomers from the region revealed the presence of five physical domains, each containing monomers from a distinct phylogenetic clade. The most distal domain contains long interspersed nucleotide element repeats that were active >35 million years ago, whereas the four proximal domains contain more recently active long interspersed nucleotide element repeats. An out-of-register, unequal recombination (i.e., crossover) detected at the edge of the X chromosomespecific alpha-satellite array (DXZ1) may reflect the most recent of a series of punctuating events during evolution that resulted in a proximal physical expansion of the X centromere. The first 18 kb of this array has 97-99% pairwise identity among all 2-kb repeat units. To perform more detailed evolutionary comparisons, we sequenced the junction between the ancient DNA of Xp and the primate-specific alpha satellite in chimpanzee, gorilla, orangutan, vervet, macaque, and baboon. The striking conservation found in all cases supports the ancestral nature of the alpha satellite at this location. These studies demonstrate that the primate X centromere appears to have evolved through repeated expansion events occurring within the central, active region of centromeric DNA, with the newly added sequences then conferring centromere function.evolution ͉ alpha satellite ͉ comparative genomics ͉ genome sequencing

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Cited by 31 publications

References 27 publications

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

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

Evidence on the chromosomal location of centromeric DNA in Plasmodium falciparum from etoposide-mediated topoisomerase-II cleavage

Progressive proximal expansion of the primate X chromosome centromere

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