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Oliveira ÉAD, Chauhan J, Silva JRD, Carvalho LADC, Dias D, Carvalho DGD, Watanabe LRM, Rebecca VW, Mills G, Lu Y, da Silva ASF, Consolaro MEL, Herlyn M, Possik PA, Goding CR, Maria-Engler SS. TOP1 modulation during melanoma progression and in adaptative resistance to BRAF and MEK inhibitors. Pharmacol Res 2021; 173:105911. [PMID: 34560251 DOI: 10.1016/j.phrs.2021.105911] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 09/03/2021] [Accepted: 09/19/2021] [Indexed: 12/26/2022]
Abstract
In melanomas, therapy resistance can arise due to a combination of genetic, epigenetic and phenotypic mechanisms. Due to its crucial role in DNA supercoil relaxation, TOP1 is often considered an essential chemotherapeutic target in cancer. However, how TOP1 expression and activity might differ in therapy sensitive versus resistant cell types is unknown. Here we show that TOP1 expression is increased in metastatic melanoma and correlates with an invasive gene expression signature. More specifically, TOP1 expression is highest in cells with the lowest expression of MITF, a key regulator of melanoma biology. Notably, TOP1 and DNA Single-Strand Break Repair genes are downregulated in BRAFi- and BRAFi/MEKi-resistant cells and TOP1 inhibition decreases invasion markers only in BRAFi/MEKi-resistant cells. Thus, we show three different phenotypes related to TOP1 levels: i) non-malignant cells with low TOP1 levels; ii) metastatic cells with high TOP1 levels and high invasiveness; and iii) BRAFi- and BRAFi/MEKi-resistant cells with low TOP1 levels and high invasiveness. Together, these results highlight the potential role of TOP1 in melanoma progression and resistance.
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Affiliation(s)
- Érica Aparecida de Oliveira
- Skin Biology Group, Clinical Chemistry and Toxicology Department, School of Pharmaceutical Sciences, University of Sao Paulo, FCF/USP, Brazil; Ludwig Institute for Cancer Research, Nuffield Department of Clinical Medicine, University of Oxford, Headington, Oxford, UK
| | - Jagat Chauhan
- Ludwig Institute for Cancer Research, Nuffield Department of Clinical Medicine, University of Oxford, Headington, Oxford, UK
| | - Julia Rezende da Silva
- Skin Biology Group, Clinical Chemistry and Toxicology Department, School of Pharmaceutical Sciences, University of Sao Paulo, FCF/USP, Brazil
| | - Larissa Anastacio da Costa Carvalho
- Skin Biology Group, Clinical Chemistry and Toxicology Department, School of Pharmaceutical Sciences, University of Sao Paulo, FCF/USP, Brazil
| | - Diogo Dias
- Ludwig Institute for Cancer Research, Nuffield Department of Clinical Medicine, University of Oxford, Headington, Oxford, UK
| | | | - Luis Roberto Masao Watanabe
- Skin Biology Group, Clinical Chemistry and Toxicology Department, School of Pharmaceutical Sciences, University of Sao Paulo, FCF/USP, Brazil
| | - Vito W Rebecca
- Molecular and Cellular Oncogenesis Program and Melanoma Research Center, Wistar Institute, Philadelphia, PA, USA; Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | | | - Yiling Lu
- The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Aloisio Souza Felipe da Silva
- Department of Pathology, Anatomic Pathology Service, University Hospital, University of São Paulo, São Paulo, Brazil
| | | | - Meenhard Herlyn
- Molecular and Cellular Oncogenesis Program and Melanoma Research Center, Wistar Institute, Philadelphia, PA, USA
| | - Patricia A Possik
- Division of Cellular Biology, Brazilian National Cancer Institute, Brazil
| | - Colin R Goding
- Ludwig Institute for Cancer Research, Nuffield Department of Clinical Medicine, University of Oxford, Headington, Oxford, UK
| | - Silvya Stuchi Maria-Engler
- Skin Biology Group, Clinical Chemistry and Toxicology Department, School of Pharmaceutical Sciences, University of Sao Paulo, FCF/USP, Brazil.
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2
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Trapped topoisomerase II initiates formation of de novo duplications via the nonhomologous end-joining pathway in yeast. Proc Natl Acad Sci U S A 2020; 117:26876-26884. [PMID: 33046655 DOI: 10.1073/pnas.2008721117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Topoisomerase II (Top2) is an essential enzyme that resolves catenanes between sister chromatids as well as supercoils associated with the over- or under-winding of duplex DNA. Top2 alters DNA topology by making a double-strand break (DSB) in DNA and passing an intact duplex through the break. Each component monomer of the Top2 homodimer nicks one of the DNA strands and forms a covalent phosphotyrosyl bond with the 5' end. Stabilization of this intermediate by chemotherapeutic drugs such as etoposide leads to persistent and potentially toxic DSBs. We describe the isolation of a yeast top2 mutant (top2-F1025Y,R1128G) the product of which generates a stabilized cleavage intermediate in vitro. In yeast cells, overexpression of the top2-F1025Y,R1128G allele is associated with a mutation signature that is characterized by de novo duplications of DNA sequence that depend on the nonhomologous end-joining pathway of DSB repair. Top2-associated duplications are promoted by the clean removal of the enzyme from DNA ends and are suppressed when the protein is removed as part of an oligonucleotide. TOP2 cells treated with etoposide exhibit the same mutation signature, as do cells that overexpress the wild-type protein. These results have implications for genome evolution and are relevant to the clinical use of chemotherapeutic drugs that target Top2.
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Morafraile EC, Hänni C, Allen G, Zeisner T, Clarke C, Johnson MC, Santos MM, Carroll L, Minchell NE, Baxter J, Banks P, Lydall D, Zegerman P. Checkpoint inhibition of origin firing prevents DNA topological stress. Genes Dev 2019; 33:1539-1554. [PMID: 31624083 PMCID: PMC6824463 DOI: 10.1101/gad.328682.119] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Accepted: 09/13/2019] [Indexed: 12/22/2022]
Abstract
A universal feature of DNA damage and replication stress in eukaryotes is the activation of a checkpoint-kinase response. In S-phase, the checkpoint inhibits replication initiation, yet the function of this global block to origin firing remains unknown. To establish the physiological roles of this arm of the checkpoint, we analyzed separation of function mutants in the budding yeast Saccharomyces cerevisiae that allow global origin firing upon replication stress, despite an otherwise normal checkpoint response. Using genetic screens, we show that lack of the checkpoint-block to origin firing results in a dependence on pathways required for the resolution of topological problems. Failure to inhibit replication initiation indeed causes increased DNA catenation, resulting in DNA damage and chromosome loss. We further show that such topological stress is not only a consequence of a failed checkpoint response but also occurs in an unperturbed S-phase when too many origins fire simultaneously. Together we reveal that the role of limiting the number of replication initiation events is to prevent DNA topological problems, which may be relevant for the treatment of cancer with both topoisomerase and checkpoint inhibitors.
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Affiliation(s)
- Esther C Morafraile
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge CB2 1QN, United Kingdom
| | - Christine Hänni
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge CB2 1QN, United Kingdom
| | - George Allen
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge CB2 1QN, United Kingdom
| | - Theresa Zeisner
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge CB2 1QN, United Kingdom
| | - Caroline Clarke
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge CB2 1QN, United Kingdom
| | - Mark C Johnson
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge CB2 1QN, United Kingdom
| | - Miguel M Santos
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge CB2 1QN, United Kingdom
| | - Lauren Carroll
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge CB2 1QN, United Kingdom
| | - Nicola E Minchell
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton, East Sussex BN1 9RQ, United Kingdom
| | - Jonathan Baxter
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton, East Sussex BN1 9RQ, United Kingdom
| | - Peter Banks
- Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Dave Lydall
- Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Philip Zegerman
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge CB2 1QN, United Kingdom
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Pannunzio NR, Lieber MR. Constitutively active Artemis nuclease recognizes structures containing single-stranded DNA configurations. DNA Repair (Amst) 2019; 83:102676. [PMID: 31377101 DOI: 10.1016/j.dnarep.2019.102676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 07/24/2019] [Accepted: 07/25/2019] [Indexed: 01/03/2023]
Abstract
The Artemis nuclease recognizes and endonucleolytically cleaves at single-stranded to double-stranded DNA (ss/dsDNA) boundaries. It is also a key enzyme in the non-homologous end joining (NHEJ) DNA double-strand break repair pathway. Previously, a truncated form, Artemis-413, was developed that is constitutively active both in vitro and in vivo. Here, we use this constitutively active form of Artemis to detect DNA structures with ss/dsDNA boundaries that arise under topological stress. Topoisomerases prevent abnormal levels of torsional stress through modulation of positive and negative supercoiling. We show that overexpression of Artemis-413 in yeast cells carrying genetic mutations that ablate topoisomerase activity have an increased frequency of DNA double-strand breaks (DSBs). Based on the biochemical activity of Artemis, this suggests an increase in ss/dsDNA-containing structures upon increased torsional stress, with DSBs arising due to Artemis cutting at these ss/dsDNA structures. Camptothecin targets topoisomerase IB (Top1), and cells treated with camptothecin show increased DSBs. We find that expression of Artemis-413 in camptothecin-treated cells leads to a reduction in DSBs, the opposite of what we find with topoisomerase genetic mutations. This contrast between outcomes not only confirms that topoisomerase mutation and topoisomerase poisoning have distinct effects on cells, but also demonstrates the usefulness of Artemis-413 to study changes in DNA structure.
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Affiliation(s)
- Nicholas R Pannunzio
- Department of Pathology, Keck School of Medicine of University of Southern California, Los Angeles, CA, 90089, USA; Norris Comprehensive Cancer Center, Keck School of Medicine of University of Southern California, Los Angeles, CA, 90089, USA.
| | - Michael R Lieber
- Department of Pathology, Keck School of Medicine of University of Southern California, Los Angeles, CA, 90089, USA; Norris Comprehensive Cancer Center, Keck School of Medicine of University of Southern California, Los Angeles, CA, 90089, USA; Department of Biological Sciences, Molecular and Computational Biology Section, University of Southern California, Los Angeles, CA, 90089, USA.
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Nitiss KC, Nitiss JL, Hanakahi LA. DNA Damage by an essential enzyme: A delicate balance act on the tightrope. DNA Repair (Amst) 2019; 82:102639. [PMID: 31437813 DOI: 10.1016/j.dnarep.2019.102639] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 06/18/2019] [Accepted: 07/01/2019] [Indexed: 01/07/2023]
Abstract
DNA topoisomerases are essential for DNA metabolic processes such as replication and transcription. Since DNA is double stranded, the unwinding needed for these processes results in DNA supercoiling and catenation of replicated molecules. Changing the topology of DNA molecules to relieve supercoiling or resolve catenanes requires that DNA be transiently cut. While topoisomerases carry out these processes in ways that minimize the likelihood of genome instability, there are several ways that topoisomerases may fail. Topoisomerases can be induced to fail by therapeutic small molecules such as by fluoroquinolones that target bacterial topoisomerases, or a variety of anti-cancer agents that target the eukaryotic enzymes. Increasingly, there have been a large number of agents and processes, including natural products and their metabolites, DNA damage, and the intrinsic properties of the enzymes that can lead to long-lasting DNA breaks that subsequently lead to genome instability, cancer, and other diseases. Understanding the processes that can interfere with topoisomerases and how cells respond when topoisomerases fail will be important in minimizing the consequences when enzymes need to transiently interfere with DNA integrity.
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Affiliation(s)
- Karin C Nitiss
- University of Illinois College of Medicine, Department of Biomedical Sciences, Rockford, IL, 61107, United States; University of Illinois College of Pharmacy, Biopharmaceutical Sciences Department, Rockford IL, 61107, United States
| | - John L Nitiss
- University of Illinois College of Pharmacy, Biopharmaceutical Sciences Department, Rockford IL, 61107, United States.
| | - Leslyn A Hanakahi
- University of Illinois College of Pharmacy, Biopharmaceutical Sciences Department, Rockford IL, 61107, United States.
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6
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Synthesis, characterization, DNA binding, topoisomerase I inhibition and antiproliferation activities of three new functionalized terpyridine platinum(II) complexes. J Inorg Biochem 2018; 192:17-24. [PMID: 30554070 DOI: 10.1016/j.jinorgbio.2018.12.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 11/27/2018] [Accepted: 12/02/2018] [Indexed: 02/04/2023]
Abstract
Three new platinum(II) complexes with pendent morpholine were synthesized, namely complex 1 ([Pt(L)Cl]CF3SO3), complex 2 ([Pt(L)(NH3)](CF3SO3)2) and complex 3 ([Pt(L)(PPh3)](CF3SO3)2), where L = 4'-[4-(4-morpholinobutyloxy)phenyl]-2,2':6',2″-terpyridine and PPh3 = triphenylphosphine. The detailed molecular structures of complex 3, L and its precursor L' (1,4'-[4-(4-bromobutyloxy)phenyl]-2,2':6',2″-terpyridine) were determined by single crystal X-ray diffraction. An evaluation of in vitro cytotoxicity for both ligand and complexes was performed by methyl thiazolyl tetrazolium (MTT) assay in three cancer cell lines and normal cells as the control, respectively. IC50 values of complexes 1-3 were lower than those exhibited for the reference drug cisplatin, and selectivity of these complexes were greater than cisplatin. Among them, complex 3 with a leaving group PPh3 was found to be the most efficacious complex against certain cell lines, especially for cisplatin-resistant A549cisR cells. These complexes were found to bind DNA, induce efficient DNA unwinding. Meanwhile, topoisomerase (Topo) I inhibitory activities by three complexes were detected, and a minimum inhibitory concentration of 15 μM of complex 3 was found totally inhibit Topo I activity.
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Tombline G, Millen JI, Polevoda B, Rapaport M, Baxter B, Van Meter M, Gilbertson M, Madrey J, Piazza GA, Rasmussen L, Wennerberg K, White EL, Nitiss JL, Goldfarb DS. Effects of an unusual poison identify a lifespan role for Topoisomerase 2 in Saccharomyces cerevisiae. Aging (Albany NY) 2017; 9:68-97. [PMID: 28077781 PMCID: PMC5310657 DOI: 10.18632/aging.101114] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 10/29/2016] [Indexed: 12/17/2022]
Abstract
A progressive loss of genome maintenance has been implicated as both a cause and consequence of aging. Here we present evidence supporting the hypothesis that an age-associated decay in genome maintenance promotes aging in Saccharomyces cerevisiae (yeast) due to an inability to sense or repair DNA damage by topoisomerase 2 (yTop2). We describe the characterization of LS1, identified in a high throughput screen for small molecules that shorten the replicative lifespan of yeast. LS1 accelerates aging without affecting proliferative growth or viability. Genetic and biochemical criteria reveal LS1 to be a weak Top2 poison. Top2 poisons induce the accumulation of covalent Top2-linked DNA double strand breaks that, if left unrepaired, lead to genome instability and death. LS1 is toxic to cells deficient in homologous recombination, suggesting that the damage it induces is normally mitigated by genome maintenance systems. The essential roles of yTop2 in proliferating cells may come with a fitness trade-off in older cells that are less able to sense or repair yTop2-mediated DNA damage. Consistent with this idea, cells live longer when yTop2 expression levels are reduced. These results identify intrinsic yTop2-mediated DNA damage as a potentially manageable cause of aging.
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Affiliation(s)
- Gregory Tombline
- Biology Department, University of Rochester, Rochester, NY 14627, USA
| | - Jonathan I Millen
- Biology Department, University of Rochester, Rochester, NY 14627, USA
| | - Bogdan Polevoda
- Biology Department, University of Rochester, Rochester, NY 14627, USA
| | - Matan Rapaport
- Biology Department, University of Rochester, Rochester, NY 14627, USA
| | - Bonnie Baxter
- Biology Department, University of Rochester, Rochester, NY 14627, USA
| | - Michael Van Meter
- Biology Department, University of Rochester, Rochester, NY 14627, USA
| | - Matthew Gilbertson
- Department of Biopharmaceutical Sciences, UIC College of Pharmacy at Rockford, Rockford, IL 61107, USA
| | - Joe Madrey
- Drug Discovery Division, Southern Research Institute, Birmingham AL, 35205, USA
| | - Gary A Piazza
- Drug Discovery Division, Southern Research Institute, Birmingham AL, 35205, USA
| | - Lynn Rasmussen
- Drug Discovery Division, Southern Research Institute, Birmingham AL, 35205, USA
| | - Krister Wennerberg
- Drug Discovery Division, Southern Research Institute, Birmingham AL, 35205, USA
| | - E Lucile White
- Drug Discovery Division, Southern Research Institute, Birmingham AL, 35205, USA
| | - John L Nitiss
- Department of Biopharmaceutical Sciences, UIC College of Pharmacy at Rockford, Rockford, IL 61107, USA
| | - David S Goldfarb
- Biology Department, University of Rochester, Rochester, NY 14627, USA
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8
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Sloan R, Huang SYN, Pommier Y, Jinks-Robertson S. Effects of camptothecin or TOP1 overexpression on genetic stability in Saccharomyces cerevisiae. DNA Repair (Amst) 2017; 59:69-75. [PMID: 28961461 DOI: 10.1016/j.dnarep.2017.09.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 09/14/2017] [Accepted: 09/15/2017] [Indexed: 10/18/2022]
Abstract
Topoisomerase I (Top1) removes DNA torsional stress by nicking and resealing one strand of DNA, and is essential in higher eukaryotes. The enzyme is frequently overproduced in tumors and is the sole target of the chemotherapeutic drug camptothecin (CPT) and its clinical derivatives. CPT stabilizes the covalent Top1-DNA cleavage intermediate, which leads to toxic double-strand breaks (DSBs) when encountered by a replication fork. In the current study, we examined genetic instability associated with CPT treatment or with Top1 overexpression in the yeast Saccharomyces cerevisiae. Two types of instability were monitored: Top1-dependent deletions in haploid strains, which do not require processing into a DSB, and instability at the repetitive ribosomal DNA (rDNA) locus in diploid strains, which reflects DSB formation. Three 2-bp deletion hotspots were examined and mutations at each were elevated either when a wild-type strain was treated with CPT or when TOP1 was overexpressed, with the mutation frequency correlating with the level of TOP1 overexpression. Under both conditions, deletions at novel positions were enriched. rDNA stability was examined by measuring loss-of-heterozygosity and as was observed previously upon CPT treatment of a wild-type strain, Top1 overexpression destabilized rDNA. We conclude that too much, as well as too little of Top1 is detrimental to eukaryotic genomes, and that CPT has destabilizing effects that extend beyond those associated with DSB formation.
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Affiliation(s)
- Roketa Sloan
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, United States
| | - Shar-Yin Naomi Huang
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, United States
| | - Yves Pommier
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, United States
| | - Sue Jinks-Robertson
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, United States.
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Abstract
Topoisomerases manage the torsional stress associated with the separation of DNA strands during transcription and DNA replication. Eukaryotic Topoisomerase I (Top1) is a Type IB enzyme that nicks and rejoins only one strand of duplex DNA, and it is especially important during transcription. By resolving transcription-associated torsional stress, Top1 reduces the accumulation of genome-destabilizing R-loops and non-B DNA structures. The DNA nicking activity of Top1, however, can also initiate genome instability in the form of illegitimate recombination, homologous recombination and mutagenesis. In this review, we focus on the diverse, and often opposing, roles of Top1 in regulating eukaryotic genome stability.
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10
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Ravishankar S, Ambady A, Awasthy D, Mudugal NV, Menasinakai S, Jatheendranath S, Guptha S, Sharma S, Balakrishnan G, Nandishaiah R, Ramachandran V, Eyermann CJ, Reck F, Rudrapatna S, Sambandamurthy VK, Sharma UK. Genetic and chemical validation identifies Mycobacterium tuberculosis topoisomerase I as an attractive anti-tubercular target. Tuberculosis (Edinb) 2015; 95:589-98. [PMID: 26073894 DOI: 10.1016/j.tube.2015.05.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 04/30/2015] [Accepted: 05/13/2015] [Indexed: 12/21/2022]
Abstract
DNA topoisomerases perform the essential function of maintaining DNA topology in prokaryotes. DNA gyrase, an essential enzyme that introduces negative supercoils, is a clinically validated target. However, topoisomerase I (Topo I), an enzyme responsible for DNA relaxation has received less attention as an antibacterial target, probably due to the ambiguity over its essentiality in many organisms. The Mycobacterium tuberculosis genome harbors a single topA gene with no obvious redundancy in its function suggesting an essential role. The topA gene could be inactivated only in the presence of a complementing copy of the gene in M. tuberculosis. Furthermore, down-regulation of topA in a genetically engineered strain of M. tuberculosis resulted in loss of bacterial viability which correlated with a concomitant depletion of intracellular Topo I levels. The topA knockdown strain of M. tuberculosis failed to establish infection in a murine model of TB and was cleared from lungs in two months post infection. Phenotypic screening of a Topo I overexpression strain led to the identification of an inhibitor, thereby providing chemical validation of this target. Thus, our work confirms the attractiveness of Topo I as an anti-mycobacterial target.
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Affiliation(s)
- Sudha Ravishankar
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
| | - Anisha Ambady
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| | - Disha Awasthy
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| | | | | | | | - Supreeth Guptha
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| | - Sreevalli Sharma
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| | | | - Radha Nandishaiah
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| | | | - Charles J Eyermann
- AstraZeneca Infection, Innovative Medicines, 35 Gatehouse Drive, Waltham, MA 02451, United States
| | - Folkert Reck
- AstraZeneca Infection, Innovative Medicines, 35 Gatehouse Drive, Waltham, MA 02451, United States
| | - Suresh Rudrapatna
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| | | | - Umender K Sharma
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India
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Xu Y, Zhou B, Wu D, Yin Z, Luo D. Baicalin modulates microRNA expression in UVB irradiated mouse skin. J Biomed Res 2013; 26:125-34. [PMID: 23554741 PMCID: PMC3597329 DOI: 10.1016/s1674-8301(12)60022-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 10/25/2011] [Accepted: 11/23/2011] [Indexed: 12/31/2022] Open
Abstract
This study aimed to evaluate the effects of baicalin on ultraviolet radiation B (UVB)-mediated microRNA (miRNA) expression in mouse skin. We determined miRNA expression profiles in UVB irradiated mice, baicalin treated irradiated mice, and untreated mice, and conducted TargetScan and Gene Ontology analyses to predict miRNA targets. Three miRNAs (mmu-miR-125a-5p, mmu-miR-146a, and mmu-miR-141) were downregulated and another three (mmu-miR-188-5p, mmu-miR-223 and mmu-miR-22) were upregulated in UVB irradiated mice compared with untreated mice. Additionally, these miRNAs were predicted to be related to photocarcinogenesis, hypomethylation and apoptosis. Three miRNAs (mmu-miR-378, mmu-miR-199a-3p and mmu-miR-181b) were downregulated and one (mmu-miR-23a) was upregulated in baicalin treated mice compared with UVB irradiated mice, and they were predicted to be related to DNA repair signaling pathway. These deregulated miRNAs are potentially involved in the pathogenesis of photodamage, and may aid treatment and prevention of UVB-induced dermatoses.
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Affiliation(s)
- Yang Xu
- Department of Dermatology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, China
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12
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Affiliation(s)
- John L Nitiss
- University of Illinois College of Pharmacy, Rockford, Illinois, United States of America.
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13
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Mécanismes moléculaires et déterminants de la réponse aux inhibiteurs de topo-isomérases I. Bull Cancer 2011; 98:1287-98. [DOI: 10.1684/bdc.2011.1474] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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14
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Niu DK, Yang YF. Why eukaryotic cells use introns to enhance gene expression: splicing reduces transcription-associated mutagenesis by inhibiting topoisomerase I cutting activity. Biol Direct 2011; 6:24. [PMID: 21592350 PMCID: PMC3118952 DOI: 10.1186/1745-6150-6-24] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Accepted: 05/18/2011] [Indexed: 11/10/2022] Open
Abstract
Background The costs and benefits of spliceosomal introns in eukaryotes have not been established. One recognized effect of intron splicing is its known enhancement of gene expression. However, the mechanism regulating such splicing-mediated expression enhancement has not been defined. Previous studies have shown that intron splicing is a time-consuming process, indicating that splicing may not reduce the time required for transcription and processing of spliced pre-mRNA molecules; rather, it might facilitate the later rounds of transcription. Because the densities of active RNA polymerase II on most genes are less than one molecule per gene, direct interactions between the splicing apparatus and transcriptional complexes (from the later rounds of transcription) are infrequent, and thus unlikely to account for splicing-mediated gene expression enhancement. Presentation of the hypothesis The serine/arginine-rich protein SF2/ASF can inhibit the DNA topoisomerase I activity that removes negative supercoiling of DNA generated by transcription. Consequently, splicing could make genes more receptive to RNA polymerase II during the later rounds of transcription, and thus affect the frequency of gene transcription. Compared with the transcriptional enhancement mediated by strong promoters, intron-containing genes experience a lower frequency of cut-and-paste processes. The cleavage and religation activity of DNA strands by DNA topoisomerase I was recently shown to account for transcription-associated mutagenesis. Therefore, intron-mediated enhancement of gene expression could reduce transcription-associated genome instability. Testing the hypothesis Experimentally test whether transcription-associated mutagenesis is lower in intron-containing genes than in intronless genes. Use bioinformatic analysis to check whether exons flanking lost introns have higher frequencies of short deletions. Implications of the hypothesis The mechanism of intron-mediated enhancement proposed here may also explain the positive correlation observed between intron size and gene expression levels in unicellular organisms, and the greater number of intron containing genes in higher organisms. Reviewers This article was reviewed by Dr Arcady Mushegian, Dr Igor B Rogozin (nominated by Dr I King Jordan) and Dr Alexey S Kondrashov. For the full reviews, please go to the Reviewer's Reports section.
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Affiliation(s)
- Deng-Ke Niu
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing 100875, China.
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15
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Role for topoisomerase 1 in transcription-associated mutagenesis in yeast. Proc Natl Acad Sci U S A 2010; 108:698-703. [PMID: 21177427 DOI: 10.1073/pnas.1012363108] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
High levels of transcription in Saccharomyces cerevisiae are associated with increased genetic instability, which has been linked to DNA damage. Here, we describe a pGAL-CAN1 forward mutation assay for studying transcription-associated mutagenesis (TAM) in yeast. In a wild-type background with no alterations in DNA repair capacity, ≈50% of forward mutations that arise in the CAN1 gene under high-transcription conditions are deletions of 2-5 bp. Furthermore, the deletions characteristic of TAM localize to discrete hotspots that coincide with 2-4 copies of a tandem repeat. Although the signature deletions of TAM are not affected by the loss of error-free or error-prone lesion bypass pathways, they are completely eliminated by deletion of the TOP1 gene, which encodes the yeast type IB topoisomerase. Hotspots can be transposed into the context of a frameshift reversion assay, which is sensitive enough to detect Top1-dependent deletions even in the absence of high transcription. We suggest that the accumulation of Top1 cleavage complexes is related to the level of transcription and that their removal leads to the signature deletions. Given the high degree of conservation between DNA metabolic processes, the links established here among transcription, Top1, and mutagenesis are likely to extend beyond the yeast system.
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16
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How DNA lesions are turned into powerful killing structures: insights from UV-induced apoptosis. Mutat Res 2008; 681:197-208. [PMID: 18845270 DOI: 10.1016/j.mrrev.2008.09.001] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Revised: 09/08/2008] [Accepted: 09/09/2008] [Indexed: 11/22/2022]
Abstract
Mammalian cells treated with ultraviolet (UV) light provide one of the best-known experimental systems for depicting the biological consequences of DNA damage. UV irradiation induces the formation of DNA photoproducts, mainly cyclobutane pyrimidine dimers (CPDs) and (6-4) pyrimidine-pyrimidone photoproducts [(6-4)PPs], that drastically impairs DNA metabolism, culminating in the induction of cell death by apoptosis. While CPDs are the most important apoptosis-inducing lesions in DNA repair proficient cells, recent data indicates that (6-4)PPs also signals for apoptosis in DNA repair deficient cells. The toxic effects of these unrepaired DNA lesions are commonly associated with transcription blockage, but there is increasing evidence supporting a role for replication blockage as an apoptosis-inducing signal. This is supported by the observations that DNA double-strand breaks (DSBs) arise at the sites of stalled replication forks, that these DSBs are potent inducers of apoptosis and that inhibition of S phase progression diminishes the apoptotic response. Reactive oxygen species, generated after exposure of mammalian cells to longer UV wavelengths, may also induce apoptotic responses. In this regard, emphasis is given to the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-OxoG), but indirect induced lesions such as lipoperoxide DNA adducts also deserve attention. ATR is the main established sensor molecule for UV-induced DNA damage. However, there is evidence that ATM as well as the MAPK pathway also play a role in the UV response by activating either the death receptor or the mitochondrial damage pathway. Adding more complexity to the subject, cells under stress suffer other types of processes that may result in cell death. Autophagy is one of these processes, with extensive cross-talks with apoptosis. No matter the mechanisms, cell death avoids cells to perpetuate mutations induced by genotoxic lesions. The understanding of such death responses may provide the means for the development of strategies for the prevention and treatment of cancer.
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17
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Abstract
Hereditary defects in the repair of DNA damage are implicated in a variety of diseases, many of which are typified by neurological dysfunction and/or increased genetic instability and cancer. Of the different types of DNA damage that arise in cells, single-strand breaks (SSBs) are the most common, arising at a frequency of tens of thousands per cell per day from direct attack by intracellular metabolites and from spontaneous DNA decay. Here, the molecular mechanisms and organization of the DNA-repair pathways that remove SSBs are reviewed and the connection between defects in these pathways and hereditary neurodegenerative disease are discussed.
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Affiliation(s)
- Keith W Caldecott
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UK.
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18
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Studies on cytotoxic, hydroxyl radical scavenging and topoisomerase inhibitory activities of extracts of Tabernaemontana divaricata (L.) R.Br. ex Roem. and Schult. Food Chem Toxicol 2008; 46:2922-7. [PMID: 18577413 DOI: 10.1016/j.fct.2008.05.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Revised: 04/07/2008] [Accepted: 05/29/2008] [Indexed: 11/22/2022]
Abstract
In the present investigation, the cytotoxic, hydroxyl radical scavenging and topoisomerase inhibition activities of Tabernaemontana divaricata (Apocynaceae) were evaluated. The extracts from leaves of the plant were prepared with different solvents viz. chloroform, methanol, ethyl acetate and hexane. In, in vitro cytotoxicity assay, with cell lines viz HCT-15 (Colon), HT-29 (Colon), 502713 (Colon), MCF-7 (Breast), PC- 3 (Prostrate), it was observed that the ethyl acetate extract was effective against only one colon cell line (502713) at the lowest dose i.e. 10 micro g/ml, whereas the chloroform extract was effective against all the three colon cancer cell lines, at 30 microg/ ml. In order to evaluate the mechanism of cytotoxicity of these extracts, they were assessed for their ability to scavenge hydroxyl radicals in plasmid nicking assay with pBR322. It was observed that all the extracts effectively inhibited the unwinding of supercoiled DNA except hexane extract, which showed the least effect. Since the expression of topo enzymes is linked with cell proliferation so the extracts were also checked for topo I and topo II inhibitory activities. It was noticed that ethyl acetate extract selectively showed inhibition of topo II in topoisomerase II relaxation assay.
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19
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Lebedeva N, Rechkunova N, Boiteux S, Lavrik O. Trapping of human DNA topoisomerase I by DNA structures mimicking intermediates of DNA repair. IUBMB Life 2008; 60:130-4. [DOI: 10.1002/iub.5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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20
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Lebedeva N, Auffret Vander Kemp P, Bjornsti MA, Lavrik O, Boiteux S. Trapping of DNA topoisomerase I on nick-containing DNA in cell free extracts of Saccharomyces cerevisiae. DNA Repair (Amst) 2006; 5:799-809. [PMID: 16713756 DOI: 10.1016/j.dnarep.2006.03.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Revised: 03/27/2006] [Accepted: 03/31/2006] [Indexed: 11/25/2022]
Abstract
The aim of the present study was to identify proteins that bind nicked DNA intermediates formed in the course of base excision repair (BER) in cell free extracts of Saccharomyces cerevisiae. In mammalian cells, nicks in DNA are targets of proteins such as PARP-1 or XRCC1 that have no homologues in yeast. One of the most promising methodologies to trap proteins that interact with damaged DNA lies in using a photocrosslinking technique with photoactivable dNTP analogues such as exo-N-{2-[N-(4-azido-2,5-difluoro-3-chloropyridine-6-yl)-3-aminopropionyl]-aminoethyl}-2'-deoxycytidine-5'-triphosphate (FAP-dCTP) for enzymatic synthesis of DNA probes with a photoreactive dNMP residue at the 3'-margin of a nick. Using this approach, we identified a major covalent DNA-protein adduct between a nick-containing 34-mer DNA duplex and a protein of a molecular mass of around 100-kDa. Unexpectedly, the formation of the 100-kDa adduct did not require the incorporation of the photoreactive dNMP residue at the 3'-margin of the nick nor exposure to near UV-light. However, the formation of the 100-kDa adduct strictly required a nick or a short gap in the DNA probe. Furthermore, the 100-kDa adduct was not detected in yeast extracts lacking DNA topoisomerase I (Top1). To further establish the nature of crosslinked protein, yeast Top1 was tagged with a Myc-epitope. In this case, the mobility of the Top1-DNA adduct increased by 7- kDa. Therefore, our data speak in favor of Top1 trapping by nicked DNA. In support of this hypothesis, purified yeast Top1 was also crosslinked to nicked DNA structures. Undamaged, uracil- and abasic (AP) site-containing DNAs were unable to trap Top1 under the same assay conditions. Since nicked DNA structures are frequently formed in the course of BER, their covalent linkage to Top1 has the potential to interfere with BER in vivo.
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Affiliation(s)
- Natalia Lebedeva
- CEA, UMR217 CNRS Radiobiologie Moléculaire et Cellulaire, route du Panorama, BP6, 92265-Fontenay aux Roses, France
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21
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Cline SD, Hanawalt PC. Topoisomerase deficiencies subtly enhance global genomic repair of ultraviolet-induced DNA damage in Saccharomyces cerevisiae. DNA Repair (Amst) 2006; 5:611-7. [PMID: 16516562 DOI: 10.1016/j.dnarep.2006.01.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Accepted: 01/23/2006] [Indexed: 11/25/2022]
Abstract
Genetic integrity depends upon the precision of all pathways that manipulate DNA. DNA repair mechanisms prevent mutations and aberrant recombination events by removing DNA damage. DNA topoisomerases maintain favorable nucleic acid topology for replication, transcription, and chromosome segregation. However, topoisomerases can also become trapped on DNA at sites of damage, and thereby, might alter the efficiency of DNA repair. The activities of the three nuclear DNA topoisomerases (Top1, Top2, and Top3) in the yeast Saccharomyces cerevisiae were examined for their influence upon the nucleotide excision repair (NER) of DNA damage induced by ultraviolet (UV) irradiation. A 10-20% increase in the global genomic repair (GGR) of cyclobutane pyrimidine dimers (CPDs) was observed with impaired Top1 or Top2 function. The GGR of 6-4 photoproducts (6-4PPs) and the strand-specific removal of CPDs from the yeast RPB2 gene were unaffected by the loss of topoisomerase activity. Even though the deletion of TOP3 conferred UV sensitivity, neither the GGR nor the strand-specific repair of UV-induced DNA damage was compromised in top3Delta yeast. Top1 and Top2 in DNA complexes near CPDs may inhibit GGR recognition of these lesions and produce protein-linked DNA breaks, resulting in CPD repair by an alternate pathway. While the physiological role of topoisomerase association with DNA damage has yet to be determined, these enzymes do not play a direct role in the NER pathways for removing UV-induced lesions in yeast.
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Affiliation(s)
- Susan D Cline
- Department of Biological Sciences, Stanford University, Stanford, CA 94305-5020, USA.
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22
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Pommier Y, Barcelo J, Rao VA, Sordet O, Jobson AG, Thibaut L, Miao Z, Seiler J, Zhang H, Marchand C, Agama K, Redon C. Repair of topoisomerase I-mediated DNA damage. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2006; 81:179-229. [PMID: 16891172 PMCID: PMC2576451 DOI: 10.1016/s0079-6603(06)81005-6] [Citation(s) in RCA: 225] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Topoisomerase I (Top1) is an abundant and essential enzyme. Top1 is the selective target of camptothecins, which are effective anticancer agents. Top1-DNA cleavage complexes can also be trapped by various endogenous and exogenous DNA lesions including mismatches, abasic sites and carcinogenic adducts. Tyrosyl-DNA phosphodiesterase (Tdp1) is one of the repair enzymes for Top1-DNA covalent complexes. Tdp1 forms a multiprotein complex that includes poly(ADP) ribose polymerase (PARP). PARP-deficient cells are hypersensitive to camptothecins and functionally deficient for Tdp1. We will review recent developments in several pathways involved in the repair of Top1 cleavage complexes and the role of Chk1 and Chk2 checkpoint kinases in the cellular responses to Top1 inhibitors. The genes conferring camptothecin hypersensitivity are compiled for humans, budding yeast and fission yeast.
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Affiliation(s)
- Yves Pommier
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, DHHS
| | - Juana Barcelo
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, DHHS
| | - V. Ashutosh Rao
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, DHHS
| | - Olivier Sordet
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, DHHS
| | - Andrew G. Jobson
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, DHHS
| | - Laurent Thibaut
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, DHHS
| | - Zheyong Miao
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, DHHS
| | - Jennifer Seiler
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, DHHS
| | - Hongliang Zhang
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, DHHS
| | - Christophe Marchand
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, DHHS
| | - Keli Agama
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, DHHS
| | - Christophe Redon
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, DHHS
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23
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Malik M, Nitiss JL. DNA repair functions that control sensitivity to topoisomerase-targeting drugs. EUKARYOTIC CELL 2004; 3:82-90. [PMID: 14871939 PMCID: PMC329506 DOI: 10.1128/ec.3.1.82-90.2004] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
DNA topoisomerases play critical roles in a wide range of cellular processes by altering DNA topology to facilitate replication, transcription, and chromosome segregation. Topoisomerases alter DNA topology by introducing transient DNA strand breaks that involve a covalent protein DNA intermediate. Many agents have been found to prevent the religation of DNA strand breaks induced by the enzymes, thereby converting the enzymes into DNA-damaging agents. Repair of the DNA damage induced by topoisomerases is significant in understanding drug resistance arising following treatment with topoisomerase-targeting drugs. We have used the fission yeast Schizosaccharomyces pombe to identify DNA repair pathways that are important for cell survival following drug treatment. S. pombe strains carrying mutations in genes required for homologous recombination such as rad22A or rad32 (homologues of RAD52 and MRE11) are hypersensitive to drugs targeting either topoisomerase I or topoisomerase II. In contrast to results observed with Saccharomyces cerevisiae, S. pombe strains defective in nucleotide excision repair are also hypersensitive to topoisomerase-targeting agents. The loss of DNA replication or DNA damage checkpoints also sensitizes cells to both topoisomerase I and topoisomerase II inhibitors. Finally, repair genes (such as the S. pombe rad8+ gene) with no obvious homologs in other systems also play important roles in causing sensitivity to topoisomerase drugs. Since the pattern of sensitivity is distinct from that seen with other systems (such as the S. cerevisiae system), our results highlight the usefulness of S. pombe in understanding how cells deal with the unique DNA damage induced by topoisomerases.
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Affiliation(s)
- Mobeen Malik
- Department of Molecular Pharmacology, St Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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24
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Tian L, Sayer JM, Jerina DM, Shuman S. Individual nucleotide bases, not base pairs, are critical for triggering site-specific DNA cleavage by vaccinia topoisomerase. J Biol Chem 2004; 279:39718-26. [PMID: 15252055 DOI: 10.1074/jbc.m407376200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vaccinia DNA topoisomerase forms a covalent DNA-(3'-phosphotyrosyl)-enzyme intermediate at a specific target site 5'-C(+5)C(+4)C(+3)T(+2)T(+1)p downward arrow N(-1) in duplex DNA. Here we study the effects of abasic lesions at individual positions of the scissile and nonscissile strands on the rate of single-turnover DNA transesterification and the cleavage-religation equilibrium. The rate of DNA incision was reduced by factors of 350, 250, 60, and 10 when abasic sites replaced the -1N, +1T, +2T, and +4C bases of the scissile strand, but abasic lesions at +5C and +3C had little or no effect. Abasic lesions in the nonscissile strand in lieu of +4G, +3G, +2A, and +1A reduced the rate of cleavage by factors of 130, 150, 10, and 5, whereas abasic lesions at +5G and -1N had no effect. The striking positional asymmetry of abasic interference on the scissile and nonscissile strands highlights the importance of individual bases, not base pairs, in promoting DNA cleavage. The rate of single-turnover DNA religation by the covalent topoisomerase-DNA complex was insensitive to abasic sites within the CCCTT sequence of the scissile strand, but an abasic lesion at the 5'-OH nucleoside (-1N) of the attacking DNA strand slowed the rate of religation by a factor of 600. Nonscissile strand abasic lesions at +1A and -1N slowed the rate of religation by factors of approximately 140 and 20, respectively, and strongly skewed the cleavage-religation equilibrium toward the covalent complex. Thus, abasic lesions immediately flanking the cleavage site act as topoisomerase poisons.
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Affiliation(s)
- Ligeng Tian
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10021, USA
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25
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Daroui P, Desai SD, Li TK, Liu AA, Liu LF. Hydrogen Peroxide Induces Topoisomerase I-mediated DNA Damage and Cell Death. J Biol Chem 2004; 279:14587-94. [PMID: 14688260 DOI: 10.1074/jbc.m311370200] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Reactive oxygen species modify DNA, generating various DNA lesions including modified bases such as 8-oxoguanine (8-oxoG). These base-modified DNA lesions have been shown to trap DNA topoisomerase I (TOP1) into covalent cleavage complexes. In this study, we have investigated the role of TOP1 in hydrogen peroxide toxicity. We showed that ectopic expression of TOP1 in Saccharomyces cerevisiae conferred sensitivity to hydrogen peroxide, and this sensitivity was dependent on RAD9 checkpoint function. Moreover, in the mammalian cell culture system, hydrogen peroxide-induced growth inhibition and apoptosis were shown to be partly TOP1-dependent as evidenced by a specific increase in resistance to hydrogen peroxide in TOP1-deficient P388/CPT45 murine leukemia cells as compared with their TOP1-proficient parental cell line P388. In addition, hydrogen peroxide was shown to induce TOP1-DNA cross-links. These results support a model in which hydrogen peroxide promotes the trapping of TOP1 on oxidative DNA lesions to form TOP1-DNA cleavage complexes that contribute to hydrogen peroxide toxicity.
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Affiliation(s)
- Parima Daroui
- Department of Pharmacology, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
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26
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Fagundes MRZK, Fernandes L, Savoldi M, Harris SD, Goldman MHS, Goldman GH. Identification of a topoisomerase I mutant, scsA1, as an extragenic suppressor of a mutation in scaA(NBS1), the apparent homolog of human nibrin in Aspergillus nidulans. Genetics 2003; 164:935-45. [PMID: 12871905 PMCID: PMC1462625 DOI: 10.1093/genetics/164.3.935] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Mre11-Rad50-Nbs1 protein complex has emerged as a central player in the human cellular DNA damage response, and recent observations suggest that these proteins are at least partially responsible for the linking of DNA damage detection to DNA repair and cell cycle checkpoint functions. Mutations in scaA(NBS1), which encodes the apparent homolog of human nibrin in Aspergillus nidulans, inhibit growth in the presence of the antitopoisomerase I drug camptothecin. This article describes the selection and characterization of extragenic suppressors of the scaA1 mutation, with the aim of identifying other proteins that interfere with the pathway or complex in which the ScaA would normally be involved. Fifteen extragenic suppressors of the scaA1 mutation were isolated. The topoisomerase I gene can complement one of these suppressors. Synergistic interaction between the scaA(NBS1) and scsA(TOP1) genes in the presence of DNA-damaging agents was observed. Overexpression of topoisomerase I in the scaA1 mutant causes increased sensitivity to DNA-damaging agents. The scsA(TOP1) and the scaA(NBS1) gene products could functionally interact in pathways that either monitor or repair DNA double-strand breaks.
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Affiliation(s)
- Marcia R Z Kress Fagundes
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, CEP 14040-903 São Paulo, Brazil
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Abstract
Cellular DNA-repair pathways involve proteins that have roles in other DNA-metabolic processes, as well as those that are dedicated to damage removal. Several proteins, which have diverse functions and are not known to have roles in DNA repair, also associate with damaged DNA. These newly discovered interactions could either facilitate or hinder the recognition of DNA damage, and so they could have important effects on DNA repair and genetic integrity. The outcome for the cell, and ultimately for the organism, might depend on which proteins arrive first at sites of DNA damage.
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Affiliation(s)
- Susan D Cline
- Department of Biological Sciences, Stanford University, 371 Serra Mall, Stanford, California 94305-5020, USA
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Current awareness on yeast. Yeast 2001. [PMID: 11746606 DOI: 10.1002/yea.691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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