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Nucleic Acids Research Feb 2009The mechanism by which type-2A topoisomerases transport one DNA duplex through a transient double-strand break produced in another exhibits fascinating traits. One of... (Review)
Review
The mechanism by which type-2A topoisomerases transport one DNA duplex through a transient double-strand break produced in another exhibits fascinating traits. One of them is the fine coupling between inter-domainal movements and ATP usage; another is their preference to transport DNA in particular directions. These capabilities have been inferred from in vitro studies but we ignore their significance inside the cell, where DNA configurations markedly differ from those of DNA in free solution. The eukaryotic type-2A enzyme, topoisomerase II, is the second most abundant chromatin protein after histones and its biological roles include the decatenation of newly replicated DNA and the relaxation of polymerase-driven supercoils. Yet, topoisomerase II is also implicated in other cellular processes such as chromatin folding and gene expression, in which the topological transformations catalysed by the enzyme are uncertain. Here, some capabilities of topoisomerase II that might be relevant to infer the enzyme performance in the context of chromatin architecture are discussed. Some aspects addressed are the importance of the DNA rejoining step to ensure genome stability, the regulation of the enzyme activity and of its putative structural role, and the selectively of DNA transport in the chromatin milieu.
Topics: Animals; Chromatin; DNA; DNA Topoisomerases, Type II; Humans; Models, Molecular
PubMed: 19059997
DOI: 10.1093/nar/gkn994 -
Frontiers in Immunology 2022Topoisomerase 2β (TOP2B) introduces transient double strand breaks in the DNA helix to remove supercoiling structures and unwind entangled DNA strains. Advances in...
Topoisomerase 2β (TOP2B) introduces transient double strand breaks in the DNA helix to remove supercoiling structures and unwind entangled DNA strains. Advances in genomic technologies have enabled the discovery of novel functions for TOP2B in processes such as releasing of the paused RNA polymerase II and maintaining the genome organization through DNA loop domains. Thus, TOP2B can regulate transcription directly by acting on transcription elongation and indirectly by controlling interactions between enhancer and promoter regions through genome folding. The identification of TOP2B mutations in humans unexpectedly revealed a unique role of TOP2B in B-cell progenitors. Here we discuss the functions of TOP2B and the mechanisms leading to the B-cell development defect in patients with TOP2B deficiency.
Topics: DNA; DNA Topoisomerases, Type II; DNA-Binding Proteins; Humans; Poly-ADP-Ribose Binding Proteins
PubMed: 36045673
DOI: 10.3389/fimmu.2022.982870 -
The British Journal of Cancer.... Sep 1994The successful use of cytotoxic agents in the clinical management of LCH depends upon the selective targeting of cells participating in the disease process. The... (Review)
Review
The successful use of cytotoxic agents in the clinical management of LCH depends upon the selective targeting of cells participating in the disease process. The topoisomerase 'poisons', currently used extensively in the treatment of aggressive malignancies, represent an intriguing class of cytotoxic agents exerting their cytostatic and cytotoxic effects at multiple levels according to cell type. The non-DNA intercalating topoisomerase II poison, etoposide (VP-16), is the "drug of first choice" in the treatment of LCH by cytotoxic chemotherapy. This major anticancer agent traps the nuclear enzyme DNA topoisomerase II on DNA in a sequence-specific manner, the processing of trapped complexes giving rise to a plethora of cellular effects not least the potential activation of pathways leading to cell cycle arrest and apoptosis. This short review describes the principles of topoisomerase inhibition, the multiplicity of cellular effects and the concept of cellular targeting in LCH. The successful treatment of LCH by cytotoxic chemotherapy will depend on both the identity of the target tissues and a clear view of therapeutic intent, given the potential for induction of haematological neoplasia.
Topics: Antineoplastic Agents; Cell Cycle; DNA Damage; DNA Topoisomerases, Type I; DNA Topoisomerases, Type II; Etoposide; Histiocytosis, Langerhans-Cell; Humans; Topoisomerase I Inhibitors; Topoisomerase II Inhibitors
PubMed: 8075006
DOI: No ID Found -
Journal of Enzyme Inhibition and... Dec 2023New thiazolopyrimidine derivatives and were synthesised. All prepared compounds were evaluated by MTT cytotoxicity assay against three human tumour cell lines....
New thiazolopyrimidine derivatives and were synthesised. All prepared compounds were evaluated by MTT cytotoxicity assay against three human tumour cell lines. Compounds and exhibited potent to strong anticancer activity that was nearly comparable or superior to Doxorubicin. Compounds exhibiting significant cytotoxicity were further selected to study their inhibitory activity on the Topo II enzyme. Compound was the most potent Topo II inhibitor with an IC value of 0.23 ± 0.01 µM, which was 1.4-fold and 3.6-fold higher than the IC values of Etoposide and Doxorubicin. Furthermore, compound showed significant cell cycle disruption and apoptosis on A549 cells compared to control cells. Molecular docking of the most active compounds illustrated proper fitting to the Topo II active site, suggesting that our designed compounds are promising candidates for the development of effective anticancer agents acting through Topo II inhibition.
Topics: Humans; Topoisomerase II Inhibitors; Molecular Structure; Structure-Activity Relationship; Molecular Docking Simulation; Pyrimidines; Antineoplastic Agents; DNA Topoisomerases, Type II; Doxorubicin; Cell Proliferation; Drug Screening Assays, Antitumor
PubMed: 36776024
DOI: 10.1080/14756366.2023.2175209 -
Oncotarget Aug 2015Although the new generation of androgen receptor (AR) antagonists like enzalutamide (ENZ) prolong survival of metastatic castration-resistant prostate cancer (CRPC),...
Although the new generation of androgen receptor (AR) antagonists like enzalutamide (ENZ) prolong survival of metastatic castration-resistant prostate cancer (CRPC), AR-driven tumors eventually recur indicating that additional therapies are required to fully block AR function. Since DNA topoisomerase II (Topo II) was demonstrated to be essential for AR to initiate gene transcription, this study tested whether catalytic inhibitors of Topo II can block AR signaling and suppress ENZ-resistant CRPC growth. Using multiple prostate cancer cell lines, we showed that catalytic Topo II inhibitors, ICRF187 and ICRF193 inhibited transcription activities of the wild-type AR, mutant ARs (F876L and W741C) and the AR-V7 splice variant. ICRF187 and ICRF193 decreased AR recruitment to target promoters and reduced AR nuclear localization. Both ICRF187 and ICRF193 also inhibited cell proliferation and delayed cell cycling at the G2/M phase. ICRF187 inhibited tumor growth of castration-resistant LNCaP and 22RV1 xenografts as well as ENZ-resistant MR49F xenografts. We conclude that catalytic Topo II inhibitors can block AR signaling and inhibit tumor growth of CRPC xenografts, identifying a potential co-targeting approach using these inhibitors in combination with AR pathway inhibitors in CRPC.
Topics: Androgen Receptor Antagonists; Animals; Cell Proliferation; DNA Topoisomerases, Type II; Disease Progression; Humans; Male; Mice; Prostatic Neoplasms, Castration-Resistant; Receptors, Androgen; Signal Transduction
PubMed: 26009876
DOI: 10.18632/oncotarget.4105 -
PLoS Neglected Tropical Diseases 2013The protozoan Giardia lamblia differentiates into infectious cysts within the human intestinal tract for disease transmission. Expression of the cyst wall protein (cwp)...
The protozoan Giardia lamblia differentiates into infectious cysts within the human intestinal tract for disease transmission. Expression of the cyst wall protein (cwp) genes increases with similar kinetics during encystation. However, little is known how their gene regulation shares common mechanisms. DNA topoisomerases maintain normal topology of genomic DNA. They are necessary for cell proliferation and tissue development as they are involved in transcription, DNA replication, and chromosome condensation. A putative topoisomerase II (topo II) gene has been identified in the G. lamblia genome. We asked whether Topo II could regulate Giardia encystation. We found that Topo II was present in cell nuclei and its gene was up-regulated during encystation. Topo II has typical ATPase and DNA cleavage activity of type II topoisomerases. Mutation analysis revealed that the catalytic important Tyr residue and cleavage domain are important for Topo II function. We used etoposide-mediated topoisomerase immunoprecipitation assays to confirm the binding of Topo II to the cwp promoters in vivo. Interestingly, Topo II overexpression increased the levels of cwp gene expression and cyst formation. Microarray analysis identified up-regulation of cwp and specific vsp genes by Topo II. We also found that the type II topoisomerase inhibitor etoposide has growth inhibition effect on Giardia. Addition of etoposide significantly decreased the levels of cwp gene expression and cyst formation. Our results suggest that Topo II has been functionally conserved during evolution and that Topo II plays important roles in induction of the cwp genes, which is key to Giardia differentiation into cysts.
Topics: Chromatin Immunoprecipitation; DNA Mutational Analysis; DNA Topoisomerases, Type II; Gene Expression Profiling; Gene Expression Regulation; Giardia lamblia; Humans; Microarray Analysis; Oocysts; Promoter Regions, Genetic; Protein Binding; Protozoan Proteins
PubMed: 23696909
DOI: 10.1371/journal.pntd.0002218 -
Nucleic Acids Research Feb 2009The catalytic steps through which DNA topoisomerases produce their biological effects and the interference of drug molecules with the enzyme-DNA cleavage complex have... (Review)
Review
The catalytic steps through which DNA topoisomerases produce their biological effects and the interference of drug molecules with the enzyme-DNA cleavage complex have been thoroughly investigated both from the biophysical and the biochemical point of view. This provides the basic structural insight on how this family of essential enzymes works in living systems and how their functions can be impaired by natural and synthetic compounds. Besides other factors, the physiological environment is known to affect substantially the biological properties of topoisomerases, a key role being played by metal ion cofactors, especially divalent ions (Mg(2+)), that are crucial to bestow and modulate catalytic activity by exploiting distinctive chemical features such as ionic size, hardness and characteristics of the coordination sphere including coordination number and geometry. Indeed, metal ions mediate fundamental aspects of the topoisomerase-driven transphosphorylation process by affecting the kinetics of the forward and the reverse steps and by modifying the enzyme conformation and flexibility. Of particular interest in type IA and type II enzymes are ionic interactions involving the Toprim fold, a protein domain conserved through evolution that contains a number of acidic residues essential for catalysis. A general two-metal ion mechanism is widely accepted to account for the biophysical and biochemical data thus far available.
Topics: Cations, Divalent; DNA; DNA Topoisomerases, Type I; DNA Topoisomerases, Type II; Magnesium; Protein Structure, Tertiary
PubMed: 19188255
DOI: 10.1093/nar/gkp024 -
The EMBO Journal Jun 2022Topoisomerase II (TOP2) unlinks chromosomes during vertebrate DNA replication. TOP2 "poisons" are widely used chemotherapeutics that stabilize TOP2 complexes on DNA,...
Topoisomerase II (TOP2) unlinks chromosomes during vertebrate DNA replication. TOP2 "poisons" are widely used chemotherapeutics that stabilize TOP2 complexes on DNA, leading to cytotoxic DNA breaks. However, it is unclear how these drugs affect DNA replication, which is a major target of TOP2 poisons. Using Xenopus egg extracts, we show that the TOP2 poisons etoposide and doxorubicin both inhibit DNA replication through different mechanisms. Etoposide induces TOP2-dependent DNA breaks and TOP2-dependent fork stalling by trapping TOP2 behind replication forks. In contrast, doxorubicin does not lead to appreciable break formation and instead intercalates into parental DNA to stall replication forks independently of TOP2. In human cells, etoposide stalls forks in a TOP2-dependent manner, while doxorubicin stalls forks independently of TOP2. However, both drugs exhibit TOP2-dependent cytotoxicity. Thus, etoposide and doxorubicin inhibit DNA replication through distinct mechanisms despite shared genetic requirements for cytotoxicity.
Topics: Animals; DNA; DNA Replication; DNA Topoisomerases, Type II; Doxorubicin; Etoposide; Humans; Poisons; Vertebrates
PubMed: 35578785
DOI: 10.15252/embj.2022110632 -
International Journal of Molecular... Nov 2017DNA Topoisomerase IIα (Topo IIα) is a ubiquitous enzyme in eukaryotes that performs the strand passage reaction where a double helix of DNA is passed through a second... (Review)
Review
DNA Topoisomerase IIα (Topo IIα) is a ubiquitous enzyme in eukaryotes that performs the strand passage reaction where a double helix of DNA is passed through a second double helix. This unique reaction is critical for numerous cellular processes. However, the enzyme also possesses a C-terminal domain (CTD) that is largely dispensable for the strand passage reaction but is nevertheless important for the fidelity of cell division. Recent studies have expanded our understanding of the roles of the Topo IIα CTD, in particular in mitotic mechanisms where the CTD is modified by Small Ubiquitin-like Modifier (SUMO), which in turn provides binding sites for key regulators of mitosis.
Topics: Adaptor Proteins, Signal Transducing; Aurora Kinase B; Catalytic Domain; Centromere; Chromatin; Cysteine Endopeptidases; DNA Topoisomerases, Type II; DNA-Binding Proteins; Humans; Intracellular Signaling Peptides and Proteins; Mitosis; Protein Serine-Threonine Kinases; Saccharomyces cerevisiae
PubMed: 29149026
DOI: 10.3390/ijms18112438 -
Microbiology and Molecular Biology... Sep 1997For many years, DNA gyrase was thought to be responsible both for unlinking replicated daughter chromosomes and for controlling negative superhelical tension in... (Review)
Review
For many years, DNA gyrase was thought to be responsible both for unlinking replicated daughter chromosomes and for controlling negative superhelical tension in bacterial DNA. However, in 1990 a homolog of gyrase, topoisomerase IV, that had a potent decatenating activity was discovered. It is now clear that topoisomerase IV, rather than gyrase, is responsible for decatenation of interlinked chromosomes. Moreover, topoisomerase IV is a target of the 4-quinolones, antibacterial agents that had previously been thought to target only gyrase. The key event in quinolone action is reversible trapping of gyrase-DNA and topoisomerase IV-DNA complexes. Complex formation with gyrase is followed by a rapid, reversible inhibition of DNA synthesis, cessation of growth, and induction of the SOS response. At higher drug concentrations, cell death occurs as double-strand DNA breaks are released from trapped gyrase and/or topoisomerase IV complexes. Repair of quinolone-induced DNA damage occurs largely via recombination pathways. In many gram-negative bacteria, resistance to moderate levels of quinolone arises from mutation of the gyrase A protein and resistance to high levels of quinolone arises from mutation of a second gyrase and/or topoisomerase IV site. For some gram-positive bacteria, the situation is reversed: primary resistance occurs through changes in topoisomerase IV while gyrase changes give additional resistance. Gyrase is also trapped on DNA by lethal gene products of certain large, low-copy-number plasmids. Thus, quinolone-topoisomerase biology is providing a model for understanding aspects of host-parasite interactions and providing ways to investigate manipulation of the bacterial chromosome by topoisomerases.
Topics: Bacteria; DNA Damage; DNA Topoisomerases, Type I; DNA Topoisomerases, Type II; DNA, Bacterial; Drug Resistance, Microbial; Genes, Bacterial; Neoplasms; Quinolones
PubMed: 9293187
DOI: 10.1128/mmbr.61.3.377-392.1997