scholarly journals Guiding functions of the C-terminal domain of topoisomerase IIα advance mitotic chromosome assembly

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Keishi Shintomi ◽  
Tatsuya Hirano
Keyword(s):  
Topoisomerase Ii ◽  
Mitotic Chromosome ◽  
Fine Tuning ◽  
Terminal Domain ◽  
Nucleosomal Dna ◽  
Egg Extracts ◽  
Guiding Functions ◽  
Topo Ii ◽  
Crowded Environments

AbstractTopoisomerase II (topo II) is one of the six proteins essential for mitotic chromatid reconstitution in vitro. It is not fully understood, however, mechanistically how this enzyme regulates this process. In an attempt to further refine the reconstitution assay, we have found that chromosomal binding of Xenopus laevis topo IIα is sensitive to buffer conditions and depends on its C-terminal domain (CTD). Enzymological assays using circular DNA substrates supports the idea that topo IIα first resolves inter-chromatid entanglements to drive individualization and then generates intra-chromatid entanglements to promote thickening. Importantly, only the latter process requires the CTD. By using frog egg extracts, we also show that the CTD contributes to proper formation of nucleosome-depleted chromatids by competing with a linker histone for non-nucleosomal DNA. Our results demonstrate that topo IIα utilizes its CTD to deliver the enzymatic core to crowded environments created during mitotic chromatid assembly, thereby fine-tuning this process.

scholarly journals Topoisomerase II does not play a scaffolding role in the organization of mitotic chromosomes assembled in Xenopus egg extracts.

1993 ◽  
Vol 120 (3) ◽  
pp. 601-612 ◽  
Author(s):  
T Hirano ◽  
T J Mitchison
Keyword(s):  
Topoisomerase Ii ◽  
Mitotic Chromosome ◽  
Chromosome Morphology ◽  
Sperm Chromatin ◽  
Mitotic Chromosomes ◽  
Egg Extracts ◽  
Xenopus Egg ◽  
Topo Ii ◽  
Xenopus Egg Extracts

We have investigated the role of topoisomerase II (topo II) in mitotic chromosome assembly and organization in vitro using Xenopus egg extracts. When sperm chromatin was incubated with mitotic extracts, the highly compact chromatin rapidly swelled and concomitantly underwent local condensation. Further incubation induced the formation of entangled thin chromatin fibers that eventually resolved into highly condensed individual chromosomes. This in vitro system made it possible to manipulate mitotic chromosomes in their assembly condition without any isolation or stabilization steps. Two complementary approaches, immunodepletion and antibody blocking, demonstrated that topo II activity is required for chromosome assembly and condensation. Once condensation was completed, however, blocking of topo II activity had little effect on the chromosome morphology. Immunofluorescent studies showed that topo II was uniformly distributed throughout the condensed chromosomes and was not restricted to the chromosomal axis. Surprisingly, all detectable topo II molecules were easily extracted from the chromosomes under mild conditions where the shape of chromosomes was well preserved. Our results show that topo II is essential for mitotic chromosome assembly, but does not play a scaffolding role in the structural maintenance of chromosomes assembled in vitro. We also present evidence that changes of DNA topology affect the distribution of topo II in mitotic chromosomes in our system.

scholarly journals Linker histone H1.8 inhibits chromatin-binding of condensins and DNA topoisomerase II to tune chromosome length and individualization

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Pavan Choppakatla ◽  
Bastiaan Dekker ◽  
Erin E Cutts ◽  
Alessandro Vannini ◽  
Job Dekker ◽  
...  
Keyword(s):  
Topoisomerase Ii ◽  
Mitotic Chromosome ◽  
Chromosome Length ◽  
Chromosome Morphology ◽  
Linker Histone ◽  
Dna Topoisomerase Ii ◽  
Dna Amount ◽  
Dna Topoisomerase ◽  
Topo Ii

DNA loop extrusion by condensins and decatenation by DNA topoisomerase II (topo II) are thought to drive mitotic chromosome compaction and individualization. Here, we reveal that the linker histone H1.8 antagonizes condensins and topo II to shape mitotic chromosome organization. In vitro chromatin reconstitution experiments demonstrate that H1.8 inhibits binding of condensins and topo II to nucleosome arrays. Accordingly, H1.8 depletion in Xenopus egg extracts increased condensins and topo II levels on mitotic chromatin. Chromosome morphology and Hi-C analyses suggest that H1.8 depletion makes chromosomes thinner and longer through shortening the average loop size and reducing the DNA amount in each layer of mitotic loops. Furthermore, excess loading of condensins and topo II to chromosomes by H1.8 depletion causes hyper-chromosome individualization and dispersion. We propose that condensins and topo II are essential for chromosome individualization, but their functions are tuned by the linker histone to keep chromosomes together until anaphase.

scholarly journals Linker histone H1.8 inhibits chromatin-binding of condensins and DNA topoisomerase II to tune chromosome compaction and individualization

2020 ◽  
Author(s):  
Pavan Choppakatla ◽  
Bastiaan Dekker ◽  
Erin E. Cutts ◽  
Alessandro Vannini ◽  
Job Dekker ◽  
...  
Keyword(s):  
Topoisomerase Ii ◽  
Chromosome Morphology ◽  
Linker Histone ◽  
Dna Topoisomerase Ii ◽  
Dna Amount ◽  
Dna Topoisomerase ◽  
Dna Loop ◽  
Egg Extracts ◽  
Topo Ii

SummaryDNA loop extrusion by condensins and decatenation by DNA topoisomerase II (topo II) drive mitotic chromosome compaction and individualization. Here, we reveal that the linker histone H1.8 regulates chromatin levels of condensins and topo II. In vitro chromatin reconstitution experiments demonstrate that H1.8 inhibits binding of condensins and topo II to nucleosome arrays. Accordingly, H1.8 depletion in Xenopus egg extracts increased condensins and topo II levels on mitotic chromatin. Chromosome morphology and Hi-C analyses suggest that H1.8 depletion makes chromosomes thinner and longer likely through shortening the average loop size and reducing DNA amount in each layer of mitotic loops. Furthermore, H1.8-mediated suppression of condensins and topo II binding to chromatin limits chromosome individualization by preventing resolution of interchromosomal linkages. While linker histones locally compact DNA by clustering nucleosomes, we propose that H1.8 controls chromosome morphology and topological organization through restricting the loading of condensins and topo II on chromatin.

The C-terminal domain of Saccharomyces cerevisiae DNA topoisomerase II

1994 ◽  
Vol 14 (5) ◽  
pp. 3197-3207
Author(s):  
P R Caron ◽  
P Watt ◽  
J C Wang
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nuclear Localization ◽  
Topoisomerase Ii ◽  
Dna Topoisomerase Ii ◽  
Dna Topoisomerase ◽  
Mutant Proteins ◽  
Terminal Domain ◽  
Catalytically Active

A set of carboxy-terminal deletion mutants of Saccharomyces cerevisiae DNA topoisomerase II were constructed for studying the functions of the carboxyl domain in vitro and in vivo. The wild-type yeast enzyme is a homodimer with 1,429 amino acid residues in each of the two polypeptides; truncation of the C terminus to Ile-1220 has little effect on the function of the enzyme in vitro or in vivo, whereas truncations extending beyond Gln-1138 yield completely inactive proteins. Several mutant enzymes with C termini in between these two residues were found to be catalytically active but unable to complement a top2-4 temperature-sensitive mutation. Immunomicroscopy results suggest that the removal of a nuclear localization signal in the C-terminal domain is likely to contribute to the physiological dysfunction of these proteins; the ability of these mutant proteins to relax supercoiled DNA in vivo shows, however, that at least some of the mutant proteins are present in the nuclei in a catalytically active form. In contrast to the ability of the catalytically active mutant proteins to relax supercoiled intracellular DNA, all mutants that do not complement the temperature-dependent lethality and high frequency of chromosomal nondisjunction of top2-4 were found to lack decatenation activity in vivo. The plausible roles of the DNA topoisomerase II C-terminal domain, in addition to providing a signal for nuclear localization, are discussed in the light of these results.

scholarly journals Mitotic chromatin condensation in vitro using somatic cell extracts and nuclei with variable levels of endogenous topoisomerase II.

1990 ◽  
Vol 111 (6) ◽  
pp. 2839-2850 ◽  
Author(s):  
E R Wood ◽  
W C Earnshaw
Keyword(s):  
Topoisomerase Ii ◽  
Condensation Reaction ◽  
Chromatin Condensation ◽  
Condensation Process ◽  
Interphase Nuclei ◽  
Culture Cells ◽  
Cell Extracts ◽  
Topo Ii ◽  
Species Specific

We report the development of a new method for producing mitotic extracts from tissue culture cells. These extracts reproducibly promote the condensation of chromatin in vitro when incubated with purified interphase nuclei. This condensation reaction is not species specific, since nuclei from chicken, human, and hamster cell lines all undergo chromatin condensation upon incubation with the extract. We have used this extract to investigate the role of DNA topoisomerase II (topo II) in the chromosome condensation process. Chromatin condensation does not require the presence of soluble topo II in the mitotic extract. However, the extent of formation of discrete chromosome-like structures correlates with the level of endogenous topo II present in the interphase nuclei. Our results further suggest that chromatin condensation in this extract may involve two processes: chromatin compaction and resolution into discrete chromosomes.

Monascin and monascinol, azaphilonoid pigments from Mortierella polycephala AM1: in silico and in vitro targeting of the angiogenic VEGFR2 kinase

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mohamed Shaaban ◽  
Mohammad Magdy El-Metwally ◽  
Amal A. I. Mekawey ◽  
Ahmed B. Abdelwahab ◽  
Maha M. Soltan
Keyword(s):  
In Silico ◽  
Topoisomerase Ii ◽  
Potent Inhibitor ◽  
Bioactive Metabolites ◽  
Cytotoxic Activities ◽  
Feather Waste ◽  
Biological Target ◽  
Topo Ii ◽  
Poultry Feather

Abstract The fungus, Mortierella polycephala is one of the most productive sources of anticancer bioactive compounds namely those of pigment nature. During our investigation of the produced bioactive metabolites by the terrestrial M. polycephala AM1 isolated from Egyptian poultry feather waste, two main azaphilonoid pigments, monascin (1) and monascinol (2) were obtained as major products; their structures were identified by 1D (1H&13C) and 2D (1H–1H COSY, HMBC) NMR and HRESI-MS spectroscopic data. Biologically, cytotoxic activities of these compounds were broadly studied compared with the fungal extract. To predict the biological target for the presumed antitumor activity, an in silico study was run toward three proteins, topoisomerase IIα, topoisomerase IIβ, and VEGFR2 kinase. Monascinol (2) was expected to be moderately active against VEGFR2 kinase without any anticipated inhibition toward topo II isoforms. The in vitro study confirmed the docked investigation consistently and introduced monascinol (2) rather than its counterpart (1) as a potent inhibitor to the tested VEGFR2 kinase. Taxonomically, the fungus was identified using morphological and genetic assessments.

scholarly journals Topoisomerase II levels and drug sensitivity in adult acute myelogenous leukemia

Blood ◽  
1994 ◽  
Vol 83 (2) ◽  
pp. 517-530 ◽  
Author(s):  
SH Kaufmann ◽  
JE Karp ◽  
RJ Jones ◽  
CB Miller ◽  
E Schneider ◽  
...  
Keyword(s):  
Acute Myelogenous Leukemia ◽  
Topoisomerase Ii ◽  
Drug Sensitivity ◽  
Myelogenous Leukemia ◽  
Clinical Samples ◽  
Immunoperoxidase Staining ◽  
Acute Myelogenous ◽  
Topo Ii

Abstract The topoisomerase (topo) II-directed agents etoposide, daunorubicin (DNR), and amsacrine (m-AMSA) are widely used in the treatment of acute myelogenous leukemia (AML). In the present study, multiple aspects of topo II-mediated drug action were examined in marrows from adult AML patients. Colony-forming assays revealed that the dose of etoposide, DNR, or m-AMSA required to diminish leukemic colony formation by 90% (LD90) varied over a greater than 20-fold range between different pretreatment marrows. Measurement of nuclear DNR accumulation in the absence and presence of quinidine revealed evidence of P-glycoprotein (Pgp) function in 8 of 82 samples at diagnosis and 5 of 36 samples at first relapse, but the largest quinidine-induced increment in DNR accumulation (< 2-fold) was too small to explain the variations in drug sensitivity. Restriction enzyme-based assays and sequencing of partial topo II alpha and topo II beta cDNAs from the most highly resistant specimens failed to demonstrate topo II gene mutations that could account for resistance. Western blotting of marrow samples containing greater than 80% blasts revealed that the content of the two topo II isoenzymes varied over a greater than 20-fold range, but did not correlate with drug sensitivity in vitro or in vivo. In addition, levels of topo II alpha and topo II beta in 46 of 47 clinical samples were lower than in human AML cell lines. Immunoperoxidase staining showed that these low topo II levels were accompanied by marked cell-to- cell heterogeneity, with topo II alpha being abundant in some blasts and diminished or absent from others. There was a trend toward increasing percentages of topo II alpha-positive cells in pretreatment marrows that contained more S-phase cells. Consistent with this observation, treatment of patients with granulocyte-macrophage colony- stimulating factor for 3 days before chemotherapy resulted in increases in topo II alpha-positive cells concomitant with increases in the number of cells traversing the cell cycle. These observations have implications for the regulation of topo II in AML, for the use of topo II-directed chemotherapy, and for future attempts to relate drug sensitivity to topo II levels in clinical material.

Topoisomerase II forms multimers in vitro: effects of metals, beta-glycerophosphate, and phosphorylation of its C-terminal domain

1994 ◽  
Vol 14 (10) ◽  
pp. 6962-6974
Author(s):  
Y S Vassetzky ◽  
Q Dang ◽  
P Benedetti ◽  
S M Gasser
Keyword(s):  
Chromosome Segregation ◽  
Protein Interactions ◽  
Topoisomerase Ii ◽  
Dna Topoisomerase Ii ◽  
Protein Protein Interactions ◽  
Dna Topoisomerase ◽  
Terminal Domain ◽  
Terminal Amino ◽  
In Vitro Effects

We present a novel assay for the study of protein-protein interactions involving DNA topoisomerase II. Under various conditions of incubation we observe that topoisomerase II forms complexes at least tetrameric in size, which can be sedimented by centrifugation through glycerol. The multimers are enzymatically active and can be visualized by electron microscopy. Dephosphorylation of topoisomerase II inhibits its multimerization, which can be restored at least partially by rephosphorylation of multiple sites within its 200 C-terminal amino acids by casein kinase II. Truncation of topoisomerase II just upstream of the major phosphoacceptor sites reduces its aggregation, rendering the truncated enzyme insensitive to either kinase treatments or phosphatase treatments. This is consistent with a model in which interactions involving the phosphorylated C-terminal domain of topoisomerase II aid either in chromosome segregation or in chromosome condensation.

scholarly journals Distribution of 11q23 breakpoints within the MLL breakpoint cluster region in de novo acute leukemia and in treatment-related acute myeloid leukemia: correlation with scaffold attachment regions and topoisomerase II consensus binding sites

Blood ◽  
1996 ◽  
Vol 87 (5) ◽  
pp. 1912-1922 ◽  
Author(s):  
PL Broeker ◽  
HG Super ◽  
MJ Thirman ◽  
H Pomykala ◽  
Y Yonebayashi ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Topoisomerase Ii ◽  
De Novo ◽  
Lymphoblastic Leukemia ◽  
Breakpoint Cluster Region ◽  
Cluster Region ◽  
Topo Ii ◽  
Acute Myeloid

Abstract A major unresolved question for 11q23 translocations involving MLL is the chromosomal mechanism(s) leading to these translocations. We have mapped breakpoints within the 8.3-kb BamHI breakpoint cluster region in 31 patients with acute lymphoblastic leukemia and acute myeloid leukemia (AML) de novo and in 8 t-AML patients. In 23 of 31 leukemia de novo patients, MLL breakpoints mapped to the centromeric half (4.57 kb) of the breakpoint cluster region, whereas those in eight de novo patients mapped to the telomeric half (3.87 kb). In contrast, only two t-AML breakpoints mapped in the centromeric half, whereas six mapped in the telomeric half. The difference in distribution of the leukemia de novo breakpoints is statistically significant (P = .02). A similar difference in distribution of breakpoints between de novo patients and t-AML patients has been reported by others. We identified a low- or weak-affinity scaffold attachment region (SAR) mapping just centromeric to the breakpoint cluster region, and a high-affinity SAR mapping within the telomeric half of the breakpoint cluster region. Using high stringency criteria to define in vitro vertebrate topoisomerase II (topo II) consensus sites, one topo II site mapped adjacent to the telomeric SAR, whereas six mapped within the SAR. Therefore, 74% of leukemia de novo and 25% of t-AML breakpoints map to the centromeric half of the breakpoint cluster region map between the two SARs; in contrast, 26% of the leukemia de novo and 75% of the t-AML patient breakpoints map to the telomeric half of the breakpoint cluster region that contains both the telomeric SAR and the topo II sites. Thus, the chromatin structure of the MLL breakpoint cluster region may be important in determining the distribution of the breakpoints. The data suggest that the mechanism(s) leading to translocations may differ in leukemia de novo and in t-AML.

scholarly journals Dynamics of human DNA topoisomerases IIα and IIβ in living cells

2002 ◽  
Vol 157 (1) ◽  
pp. 31-44 ◽  
Author(s):  
Morten O. Christensen ◽  
Morten K. Larsen ◽  
Hans Ullrich Barthelmes ◽  
Robert Hock ◽  
Claus L. Andersen ◽  
...  
Keyword(s):  
Structural Component ◽  
Mitotic Chromosome ◽  
Proliferating Cells ◽  
Dna Topoisomerase ◽  
Genomic Changes ◽  
Human Dna ◽  
Catalytic Dna ◽  
Topo Ii ◽  
Chromosome Scaffold

DNA topoisomerase (topo) II catalyses topological genomic changes essential for many DNA metabolic processes. It is also regarded as a structural component of the nuclear matrix in interphase and the mitotic chromosome scaffold. Mammals have two isoforms (α and β) with similar properties in vitro. Here, we investigated their properties in living and proliferating cells, stably expressing biofluorescent chimera of the human isozymes. Topo IIα and IIβ behaved similarly in interphase but differently in mitosis, where only topo IIα was chromosome associated to a major part. During interphase, both isozymes joined in nucleolar reassembly and accumulated in nucleoli, which seemed not to involve catalytic DNA turnover because treatment with teniposide (stabilizing covalent catalytic DNA intermediates of topo II) relocated the bulk of the enzymes from the nucleoli to nucleoplasmic granules. Photobleaching revealed that the entire complement of both isozymes was completely mobile and free to exchange between nuclear subcompartments in interphase. In chromosomes, topo IIα was also completely mobile and had a uniform distribution. However, hypotonic cell lysis triggered an axial pattern. These observations suggest that topo II is not an immobile, structural component of the chromosomal scaffold or the interphase karyoskeleton, but rather a dynamic interaction partner of such structures.

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