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Archives of Toxicology Apr 2017Type II DNA-topoisomerases (topo II) play a crucial role in the maintenance of DNA topology. Previously, fungi of the Alternaria genus were found to produce mycotoxins... (Comparative Study)
Comparative Study
Type II DNA-topoisomerases (topo II) play a crucial role in the maintenance of DNA topology. Previously, fungi of the Alternaria genus were found to produce mycotoxins that target human topo II. These results implied the question why a fungus should produce secondary metabolites that target a human enzyme. In the current work, the homology between human topo II and its bacterial equivalent, gyrase, served as basis to study a potential dual inhibition of both enzymes by mycotoxins. A total of 15 secondary metabolites produced by fungi of the genera Alternaria and Fusarium were assessed for their impact on topo II of human and bacterial origin in the decatenation and the supercoiling assay, respectively. In line with the theory of dual topo II inhibition, six of the tested Alternaria mycotoxins were active against both enzymes, the dibenzo-α-pyrones alternariol (AOH) and alternariol monomethyl ether (AME), as well as the perylene-quinones altertoxin I (ATX I) and II (ATX II), alterperylenol (ALP) and stemphyltoxin III (STTX III). The Alternaria metabolites altersetin (ALN), macrosporin (MAC), altenusine (ALS) and pyrenophorol (PYR) impaired the function of human topo II, but did not show any effect on gyrase. The potency to inhibit topo II activity declined in the row STTX III (initial inhibitory concentration 10 µM) > AOH (25 µM) = AME (25 µM) = ALS (25 µM) = ATX II (25 µM) > ALN (50 µM) = ATX I (50 µM) > ALP (75 µM) = PYR (75 µM) > MAC (150 µM). Inhibition of gyrase activity was most pronounced for AOH and AME (initial inhibitory concentration 10 µM) followed by ATX II (25 µM) > ATX I = ALP = STTX III (50 µM). In contrast, none of the investigated Fusarium mycotoxins deoxynivalenol (DON), fumonisin B1, fusarin C and moniliformin, as well as the Alternaria metabolite tentoxin, had any impact on the activity of neither human nor bacterial topo II.
Topics: Alternaria; DNA Gyrase; DNA Topoisomerases, Type II; Dose-Response Relationship, Drug; Fusarium; Humans; Mycotoxins; Secondary Metabolism; Topoisomerase II Inhibitors
PubMed: 27682608
DOI: 10.1007/s00204-016-1855-z -
Chemical Research in Toxicology Apr 20211,2-Naphthoquinone, a secondary metabolite of naphthalene, is an environmental pollutant found in diesel exhaust particles that displays cytotoxic and genotoxic...
1,2-Naphthoquinone, a secondary metabolite of naphthalene, is an environmental pollutant found in diesel exhaust particles that displays cytotoxic and genotoxic properties. Because many quinones have been shown to act as topoisomerase II poisons, the effects of this compound on DNA cleavage mediated by human topoisomerase IIα and IIβ were examined. The compound increased the levels of double-stranded DNA breaks generated by both enzyme isoforms and did so better than a series of naphthoquinone derivatives. Furthermore, 1,2-naphthoquinone was a more efficacious poison against topoisomerase IIα than IIβ. Topoisomerase II poisons can be classified as interfacial (which interact noncovalently at the enzyme-DNA interface and increase DNA cleavage by blocking ligation) or covalent (which adduct the protein and increase DNA cleavage by closing the N-terminal gate of the enzyme). Therefore, experiments were performed to determine the mechanistic basis for the actions of 1,2-naphthoquinone. In contrast to results with etoposide (an interfacial poison), the activity of 1,2-naphthoquinone against topoisomerase IIα was abrogated in the presence of sulfhydryl and reducing agents. Moreover, the compound inhibited cleavage activity when incubated with the enzyme prior to the addition of DNA and induced virtually no cleavage with the catalytic core of the enzyme. It also induced stable covalent topoisomerase IIα-DNA cleavage complexes and was a partial inhibitor of DNA ligation. Findings were also consistent with 1,2-naphthoquinone acting as a covalent poison of topoisomerase IIβ; however, mechanistic studies with this isoform were less conclusive. Whereas the activity of 1,2-naphthoquinone was blocked in the presence of a sulfhydryl reagent, it was much less sensitive to the presence of a reducing agent. Furthermore, the reduced form of 1,2-naphthoquinone, 1,2-dihydroxynaphthalene, displayed high activity against the β isoform. Taken together, results suggest that 1,2-naphthoquinone increases topoisomerase II-mediated double-stranded DNA scission (at least in part) by acting as a covalent poison of the human type II enzymes.
Topics: DNA Cleavage; DNA Topoisomerases, Type II; Humans; Molecular Structure; Naphthoquinones; Recombinant Proteins; Topoisomerase II Inhibitors
PubMed: 33760604
DOI: 10.1021/acs.chemrestox.0c00492 -
Drug Discoveries & Therapeutics Oct 2012DNA topoisomerase II (TOP2) is a well-known anticancer target. Its inhibitors are among the most effective anticancer drugs currently in clinical use. TOP2-targeting... (Review)
Review
DNA topoisomerase II (TOP2) is a well-known anticancer target. Its inhibitors are among the most effective anticancer drugs currently in clinical use. TOP2-targeting agents fall into two major classes of "Topo poisons" and "Topo inhibitors" based on their mechanisms of action. Mammalian cells possess two genetically distinct TOP2 isoforms, TOP2α and TOP2β, that are differentially regulated and play different roles in living cells. Compared to TOP2β, TOP2α may be an efficacious and safe chemotherapeutic target for cancer treatment. This review discusses the advantage of targeting TOP2α over TOP2β and action of various agents on TOP2α.
Topics: Animals; Antigens, Neoplasm; DNA Topoisomerases, Type II; DNA-Binding Proteins; Drug Design; Humans; Isoenzymes; Molecular Structure; Molecular Targeted Therapy; Neoplasms; Poly-ADP-Ribose Binding Proteins; Structure-Activity Relationship; Topoisomerase II Inhibitors
PubMed: 23229142
DOI: No ID Found -
Genes Oct 2019DNA topoisomerase II (TOP2) plays a critical role in many processes such as replication and transcription, where it resolves DNA structures and relieves torsional... (Review)
Review
DNA topoisomerase II (TOP2) plays a critical role in many processes such as replication and transcription, where it resolves DNA structures and relieves torsional stress. Recent evidence demonstrated the association of TOP2 with topologically associated domains (TAD) boundaries and CCCTC-binding factor (CTCF) binding sites. At these sites, TOP2 promotes interactions between enhancers and gene promoters, and relieves torsional stress that accumulates at these physical barriers. Interestingly, in executing its enzymatic function, TOP2 contributes to DNA fragility through re-ligation failure, which results in persistent DNA breaks when unrepaired or illegitimately repaired. Here, we discuss the biological processes for which TOP2 is required and the steps at which it can introduce DNA breaks. We describe the repair processes that follow removal of TOP2 adducts and the resultant broken DNA ends, and present how these processes can contribute to disease-associated mutations. Furthermore, we examine the involvement of TOP2-induced breaks in the formation of oncogenic translocations of leukemia and papillary thyroid cancer, as well as the role of TOP2 and proteins which repair TOP2 adducts in other diseases. The participation of TOP2 in generating persistent DNA breaks and leading to diseases such as cancer, could have an impact on disease treatment and prevention.
Topics: CCCTC-Binding Factor; Chromatin; DNA; DNA Breaks, Double-Stranded; DNA Repair; DNA Topoisomerases, Type II; Humans; Leukemia, Myeloid, Acute; Thyroid Cancer, Papillary; Topoisomerase II Inhibitors; Torsion, Mechanical
PubMed: 31614754
DOI: 10.3390/genes10100791 -
Molecular Microbiology Nov 2006DNA topoisomerases are the key enzymes involved in carrying out high precision DNA transactions inside the cells. However, they are detrimental to the cell when a wide... (Review)
Review
DNA topoisomerases are the key enzymes involved in carrying out high precision DNA transactions inside the cells. However, they are detrimental to the cell when a wide variety of topoisomerase-targeted drugs generate cytotoxic lesions by trapping the enzymes in covalent complexes on the DNA. The discovery of unusual heterodimeric topoisomerase I in kinetoplastid family added a new twist in topoisomerase research related to evolution, functional conservation and their preferential sensitivity to Camptothecin. On the other hand, structural and mechanistic studies on kinetoplastid topoisomerase II delineate some distinguishing features that differentiate the parasitic enzyme from its prokaryotic and eukaryotic counterparts. This review summarizes the recent advances in research in kinetoplastid topoisomerases, their evolutionary significance and the death of the unicellular parasite Leishmania donovani induced by topoisomerase I inhibitor camptothecin.
Topics: Animals; Antiprotozoal Agents; Apoptosis; Camptothecin; DNA Topoisomerases, Type I; DNA Topoisomerases, Type II; Enzyme Inhibitors; Evolution, Molecular; Humans; Kinetoplastida; Topoisomerase I Inhibitors; Topoisomerase II Inhibitors
PubMed: 17042788
DOI: 10.1111/j.1365-2958.2006.05428.x -
Sheng Li Xue Bao : [Acta Physiologica... Feb 2016Topoisomerases are nuclear enzymes that regulate the overwinding or underwinding of DNA helix during replication, transcription, recombination, repair, and chromatin...
Topoisomerases are nuclear enzymes that regulate the overwinding or underwinding of DNA helix during replication, transcription, recombination, repair, and chromatin remodeling. These enzymes perform topological transformations by providing a transient DNA break, through which the unique problems of DNA entanglement that occur owing to unwinding and rewinding of the DNA helix can be resolved. In mammals, topoisomerases are classified into two types, type I topoisomerase (Top1) and type II topoisomerase (Top2), depending on the number of strands cut in one round of action. Top1 induces single-strand breaks in DNA, and Top2 induces double-strand breaks. In cells from vertebrate species, there are two forms of Top2, designated alpha and beta. Top2α is involved in the cellular proliferation and pluripotency, while Top2β plays key roles in neurodevelopment. In this review, we cover recent advances in structural, mechanistic and functional insights into Top2.
Topics: Animals; Cell Proliferation; DNA Replication; DNA Topoisomerases, Type II
PubMed: 26915327
DOI: No ID Found -
Proceedings of the National Academy of... Jan 2022Topoisomerases nick and reseal DNA to relieve torsional stress associated with transcription and replication and to resolve structures such as knots and catenanes....
Topoisomerases nick and reseal DNA to relieve torsional stress associated with transcription and replication and to resolve structures such as knots and catenanes. Stabilization of the yeast Top2 cleavage intermediates is mutagenic in yeast, but whether this extends to higher eukaryotes is less clear. Chemotherapeutic topoisomerase poisons also elevate cleavage, resulting in mutagenesis. Here, we describe p.K743N mutations in human topoisomerase hTOP2α and link them to a previously undescribed mutator phenotype in cancer. Overexpression of the orthologous mutant protein in yeast generated a characteristic pattern of 2- to 4-base pair (bp) duplications resembling those in tumors with p.K743N. Using mutant strains and biochemical analysis, we determined the genetic requirements of this mutagenic process and showed that it results from trapping of the mutant yeast yTop2 cleavage complex. In addition to 2- to 4-bp duplications, hTOP2α p.K743N is also associated with deletions that are absent in yeast. We call the combined pattern of duplications and deletions ID_TOP2α. All seven tumors carrying the hTOP2α p.K743N mutation showed ID_TOP2α, while it was absent from all other tumors examined ( = 12,269). Each tumor with the ID_TOP2α signature had indels in several known cancer genes, which included frameshift mutations in tumor suppressors PTEN and TP53 and an activating insertion in BRAF. Sequence motifs found at ID_TOP2α mutations were present at 80% of indels in cancer-driver genes, suggesting that ID_TOP2α mutagenesis may contribute to tumorigenesis. The results reported here shed further light on the role of topoisomerase II in genome instability.
Topics: Alleles; Amino Acid Substitution; Base Sequence; Cell Survival; DNA Damage; DNA Mutational Analysis; DNA Topoisomerases, Type II; Gene Duplication; Gene Rearrangement; Genetic Predisposition to Disease; Genotype; Humans; INDEL Mutation; Mutagenesis; Mutation; Neoplasms; Oncogenes; Phenotype; Poly-ADP-Ribose Binding Proteins; Sequence Deletion
PubMed: 35058360
DOI: 10.1073/pnas.2114024119 -
The Journal of Biological Chemistry Jul 1998The interaction of topoisomerase II with its DNA cleavage site is critical to the physiological functions of the enzyme. Despite this importance, the specific enzyme-DNA...
The interaction of topoisomerase II with its DNA cleavage site is critical to the physiological functions of the enzyme. Despite this importance, the specific enzyme-DNA interactions that drive topoisomerase II-mediated DNA cleavage and religation are poorly understood. Therefore, to dissect interactions between the enzyme and its cleavage site, abasic DNA lesions were incorporated into a bilaterally symmetrical and identical cleavage site. Results indicate that topoisomerase II has unique interactions with each position of the 4-base overhang generated by enzyme-mediated DNA cleavage. Lesions located 2 bases 3' to the point of scission stimulated cleavage the most, whereas those 3 bases from the point of scission stimulated cleavage the least. Moreover, an additive and in some cases synergistic cleavage enhancement was observed in oligonucleotides that contained multiple DNA lesions, with levels reaching >60-fold higher than the wild-type substrate. Finally, topoisomerase II efficiently cleaved and religated a DNA substrate in which apyrimidinic sites were simultaneously incorporated at every position on one strand of the 4-base overhang. Therefore, unlike classical DNA ligases in which base pairing is the driving force behind closure of the DNA break, it appears that for topoisomerase II, the enzyme is responsible for the spatial orientation of the DNA termini for ligation.
Topics: Base Composition; DNA; DNA Topoisomerases, Type II; Oligonucleotides; Structure-Activity Relationship
PubMed: 9660751
DOI: 10.1074/jbc.273.29.17999 -
Scientific Reports Nov 2021DNA topoisomerase II (TOP2) is a nuclear protein that resolves DNA topological problems and plays critical roles in multiple nuclear processes. Human cells have two TOP2...
DNA topoisomerase II (TOP2) is a nuclear protein that resolves DNA topological problems and plays critical roles in multiple nuclear processes. Human cells have two TOP2 proteins, TOP2A and TOP2B, that are localized in both the nucleoplasm and nucleolus. Previously, ATP depletion was shown to augment the nucleolar localization of TOP2B, but the molecular details of subnuclear distributions, particularly of TOP2A, remained to be fully elucidated in relation to the status of cellular ATP. Here, we analyzed the nuclear dynamics of human TOP2A and TOP2B in ATP-depleted cells. Both proteins rapidly translocated from the nucleoplasm to the nucleolus in response to ATP depletion. FRAP analysis demonstrated that they were highly mobile in the nucleoplasm and nucleolus. The nucleolar retention of both proteins was sensitive to the RNA polymerase I inhibitor BMH-21, and the TOP2 proteins in the nucleolus were immediately dispersed into the nucleoplasm by BMH-21. Under ATP-depleted conditions, the TOP2 poison etoposide was less effective, indicating the therapeutic relevance of TOP2 subnuclear distributions. These results give novel insights into the subnuclear dynamics of TOP2 in relation to cellular ATP levels and also provide discussions about its possible mechanisms and biological significance.
Topics: Adenosine Triphosphate; Cell Nucleolus; DNA Topoisomerases, Type II; Enzyme Inhibitors; Etoposide; HeLa Cells; Heterocyclic Compounds, 4 or More Rings; Humans; Poly-ADP-Ribose Binding Proteins; RNA Polymerase I; Topoisomerase II Inhibitors; Translocation, Genetic
PubMed: 34728715
DOI: 10.1038/s41598-021-00958-4 -
Molecules (Basel, Switzerland) Jan 2021Pyrimido-pyrimidine derivatives have been developed as rigid merbarone analogues. In a previous study, these compounds showed potent antiproliferative activity and...
Pyrimido-pyrimidine derivatives have been developed as rigid merbarone analogues. In a previous study, these compounds showed potent antiproliferative activity and efficiently inhibited topoisomerase IIα. To further extend the structure-activity relationships on pyrimido-pyrimidines, a novel series of analogues was synthesized by a two-step procedure. Analogues - bear small alky groups at positions 1 and 3 of the pyrimido-pyrimidine scaffold whereas at position 6a (4-chloro)phenyl substituent was inserted. The basic side chains introduced at position 7 were selected on the basis of the previously developed structure-activity relationships. The antiproliferative activity of the novel compounds proved to be affected by both the nature of the basic side chain and the substituents on the pyrimido-pyrimidine moiety. Derivatives and were identified as the most promising molecules still showing reduced antiproliferative activity in comparison with the previously prepared pyrimido-pyrimidine analogues. In topoisomerase IIα- docking complex, the ligand would poorly interact with the enzyme and assume a different orientation in comparison with bioactive conformation.
Topics: Antineoplastic Agents; Cell Proliferation; DNA Topoisomerases, Type II; Female; Humans; MCF-7 Cells; Molecular Docking Simulation; Neoplasm Proteins; Neoplasms; Poly-ADP-Ribose Binding Proteins; Thiobarbiturates; Topoisomerase II Inhibitors
PubMed: 33494519
DOI: 10.3390/molecules26030557