1
|
Saha LK, Sun Y, Saha S, Yang X, Pommier Y. PARP1-driven repair of topoisomerase IIIα DNA-protein crosslinks by FEN1. Cell Rep 2024; 43:114522. [PMID: 39028621 DOI: 10.1016/j.celrep.2024.114522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 04/28/2024] [Accepted: 07/03/2024] [Indexed: 07/21/2024] Open
Abstract
Persistent DNA-protein crosslinks formed by human topoisomerase IIIα (TOP3A-DPCs) interfere with DNA metabolism and lead to genome damage and cell death. Recently, we demonstrated that such abortive TOP3A-DPCs are ubiquitylated and proteolyzed by Spartan (SPRTN). Here, we identify transient poly(ADP-ribosylation) (PARylation) in addition to ubiquitylation as a signaling mechanism for TOP3A-DPC repair and provide evidence that poly(ADP-ribose) polymerase 1 (PARP1) drives the repair of TOP3A-DPCs by recruiting flap endonuclease 1 (FEN1) to the TOP3A-DPCs. We find that blocking PARylation attenuates the interaction of FEN1 and TOP3A and that TOP3A-DPCs accumulate in cells with compromised PARP1 activity and in FEN1-deficient cells. We also show that PARP1 suppresses TOP3A-DPC ubiquitylation and that inhibiting the ubiquitin-activating enzyme E1 (UBE1) increases TOP3A-DPCs, consistent with ubiquitylation serving as a signaling mechanism for TOP3A-DPC repair mediated by SPRTN and TDP2. We propose that two concerted pathways repair TOP3A-DPCs: PARylation-driven FEN1 excision and ubiquitylation-driven SPRTN-TDP2 excision.
Collapse
Affiliation(s)
- Liton Kumar Saha
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
| | - Yilun Sun
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Sourav Saha
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Xi Yang
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Yves Pommier
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
| |
Collapse
|
2
|
Vaitsiankova A, Burdova K, Sobol M, Gautam A, Benada O, Hanzlikova H, Caldecott KW. PARP inhibition impedes the maturation of nascent DNA strands during DNA replication. Nat Struct Mol Biol 2022; 29:329-338. [PMID: 35332322 PMCID: PMC9010290 DOI: 10.1038/s41594-022-00747-1] [Citation(s) in RCA: 70] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 02/14/2022] [Indexed: 12/15/2022]
Abstract
Poly(ADP-ribose) polymerase 1 (PARP1) is implicated in the detection and processing of unligated Okazaki fragments and other DNA replication intermediates, highlighting such structures as potential sources of genome breakage induced by PARP inhibition. Here, we show that PARP1 activity is greatly elevated in chicken and human S phase cells in which FEN1 nuclease is genetically deleted and is highest behind DNA replication forks. PARP inhibitor reduces the integrity of nascent DNA strands in both wild-type chicken and human cells during DNA replication, and does so in FEN1-/- cells to an even greater extent that can be detected as postreplicative single-strand nicks or gaps. Collectively, these data show that PARP inhibitors impede the maturation of nascent DNA strands during DNA replication, and implicate unligated Okazaki fragments and other nascent strand discontinuities in the cytotoxicity of these compounds.
Collapse
Affiliation(s)
- Alina Vaitsiankova
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
| | - Kamila Burdova
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
| | - Margarita Sobol
- Laboratory of Genome Dynamics, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague 4, Czech Republic
| | - Amit Gautam
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
| | - Oldrich Benada
- Laboratory of Molecular Structure Characterization, Institute of Microbiology of the Czech Academy of Sciences, Prague 4, Czech Republic
| | - Hana Hanzlikova
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK.
- Laboratory of Genome Dynamics, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague 4, Czech Republic.
| | - Keith W Caldecott
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK.
- Laboratory of Genome Dynamics, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague 4, Czech Republic.
| |
Collapse
|
3
|
Wilson DM, Deacon AM, Duncton MAJ, Pellicena P, Georgiadis MM, Yeh AP, Arvai AS, Moiani D, Tainer JA, Das D. Fragment- and structure-based drug discovery for developing therapeutic agents targeting the DNA Damage Response. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 163:130-142. [PMID: 33115610 PMCID: PMC8666131 DOI: 10.1016/j.pbiomolbio.2020.10.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 10/13/2020] [Accepted: 10/23/2020] [Indexed: 12/12/2022]
Abstract
Cancer will directly affect the lives of over one-third of the population. The DNA Damage Response (DDR) is an intricate system involving damage recognition, cell cycle regulation, DNA repair, and ultimately cell fate determination, playing a central role in cancer etiology and therapy. Two primary therapeutic approaches involving DDR targeting include: combinatorial treatments employing anticancer genotoxic agents; and synthetic lethality, exploiting a sporadic DDR defect as a mechanism for cancer-specific therapy. Whereas, many DDR proteins have proven "undruggable", Fragment- and Structure-Based Drug Discovery (FBDD, SBDD) have advanced therapeutic agent identification and development. FBDD has led to 4 (with ∼50 more drugs under preclinical and clinical development), while SBDD is estimated to have contributed to the development of >200, FDA-approved medicines. Protein X-ray crystallography-based fragment library screening, especially for elusive or "undruggable" targets, allows for simultaneous generation of hits plus details of protein-ligand interactions and binding sites (orthosteric or allosteric) that inform chemical tractability, downstream biology, and intellectual property. Using a novel high-throughput crystallography-based fragment library screening platform, we screened five diverse proteins, yielding hit rates of ∼2-8% and crystal structures from ∼1.8 to 3.2 Å. We consider current FBDD/SBDD methods and some exemplary results of efforts to design inhibitors against the DDR nucleases meiotic recombination 11 (MRE11, a.k.a., MRE11A), apurinic/apyrimidinic endonuclease 1 (APE1, a.k.a., APEX1), and flap endonuclease 1 (FEN1).
Collapse
Affiliation(s)
- David M Wilson
- Hasselt University, Biomedical Research Institute, Diepenbeek, Belgium; Boost Scientific, Heusden-Zolder, Belgium; XPose Therapeutics Inc., San Carlos, CA, USA
| | - Ashley M Deacon
- Accelero Biostructures Inc., San Francisco, CA, USA; XPose Therapeutics Inc., San Carlos, CA, USA
| | | | | | - Millie M Georgiadis
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA; XPose Therapeutics Inc., San Carlos, CA, USA
| | - Andrew P Yeh
- Accelero Biostructures Inc., San Francisco, CA, USA
| | - Andrew S Arvai
- Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - Davide Moiani
- Department of Cancer Biology, MD Anderson Cancer Center, Houston, TX, USA; Department of Molecular and Cellular Oncology, MD Anderson Cancer Center, Houston, TX, USA
| | - John A Tainer
- Department of Cancer Biology, MD Anderson Cancer Center, Houston, TX, USA; Department of Molecular and Cellular Oncology, MD Anderson Cancer Center, Houston, TX, USA
| | - Debanu Das
- Accelero Biostructures Inc., San Francisco, CA, USA; XPose Therapeutics Inc., San Carlos, CA, USA.
| |
Collapse
|
4
|
Ma Z, Wang W, Wang S, Zhao X, Ma Y, Wu C, Hu Z, He L, Pan F, Guo Z. Symmetrical dimethylation of H4R3: A bridge linking DNA damage and repair upon oxidative stress. Redox Biol 2020; 37:101653. [PMID: 32739156 PMCID: PMC7767741 DOI: 10.1016/j.redox.2020.101653] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 06/27/2020] [Accepted: 07/20/2020] [Indexed: 01/31/2023] Open
Abstract
The DNA lesions caused by oxidative damage are principally repaired by the base excision repair (BER) pathway. 8-oxoguanine DNA glycosylase 1 (OGG1) initiates BER through recognizing and cleaving the oxidatively damaged nucleobase 8-oxo-7,8-dihydroguanine (8-oxoG). How the BER machinery detects and accesses lesions within the context of chromatin is largely unknown. Here, we found that the symmetrical dimethylarginine of histone H4 (producing H4R3me2s) serves as a bridge between DNA damage and subsequent repair. Intracellular H4R3me2s was significantly increased after treatment with the DNA oxidant reagent H2O2, and this increase was regulated by OGG1, which could directly interact with the specific arginine methyltransferase, PRMT5. Arginine-methylated H4R3 could associate with flap endonuclease 1 (FEN1) and enhance its nuclease activity and BER efficiency. Furthermore, cells with a decreased level of H4R3me2s were more susceptible to DNA-damaging agents and accumulated more DNA damage lesions in their genome. Taken together, these results demonstrate that H4R3me2s can be recognized as a reader protein that senses DNA damage and a writer protein that promotes DNA repair.
Collapse
Affiliation(s)
- Zhuang Ma
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wen Yuan Road, Nanjing, 210023, China; Institute of DNA Repair Diseases, School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Wentao Wang
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wen Yuan Road, Nanjing, 210023, China; Department of Health Technology, Technical University of Denmark, Kongens Lyngby DK-2800, Denmark
| | - Shiwei Wang
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wen Yuan Road, Nanjing, 210023, China
| | - Xingqi Zhao
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wen Yuan Road, Nanjing, 210023, China
| | - Ying Ma
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wen Yuan Road, Nanjing, 210023, China
| | - Congye Wu
- Department of Oncology, Nanjing First Hospital, Nanjing Medical University, 68, Changle Road, Nanjing, 210006, China
| | - Zhigang Hu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wen Yuan Road, Nanjing, 210023, China
| | - Lingfeng He
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wen Yuan Road, Nanjing, 210023, China
| | - Feiyan Pan
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wen Yuan Road, Nanjing, 210023, China.
| | - Zhigang Guo
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wen Yuan Road, Nanjing, 210023, China.
| |
Collapse
|
5
|
Kim DV, Makarova AV, Miftakhova RR, Zharkov DO. Base Excision DNA Repair Deficient Cells: From Disease Models to Genotoxicity Sensors. Curr Pharm Des 2020; 25:298-312. [PMID: 31198112 DOI: 10.2174/1381612825666190319112930] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 03/13/2019] [Indexed: 12/29/2022]
Abstract
Base excision DNA repair (BER) is a vitally important pathway that protects the cell genome from many kinds of DNA damage, including oxidation, deamination, and hydrolysis. It involves several tightly coordinated steps, starting from damaged base excision and followed by nicking one DNA strand, incorporating an undamaged nucleotide, and DNA ligation. Deficiencies in BER are often embryonic lethal or cause morbid diseases such as cancer, neurodegeneration, or severe immune pathologies. Starting from the early 1980s, when the first mammalian cell lines lacking BER were produced by spontaneous mutagenesis, such lines have become a treasure trove of valuable information about the mechanisms of BER, often revealing unexpected connections with other cellular processes, such as antibody maturation or epigenetic demethylation. In addition, these cell lines have found an increasing use in genotoxicity testing, where they provide increased sensitivity and representativity to cell-based assay panels. In this review, we outline current knowledge about BER-deficient cell lines and their use.
Collapse
Affiliation(s)
- Daria V Kim
- Novosibirsk State University, 2 Pirogova St., Novosibirsk 630090, Russian Federation
| | - Alena V Makarova
- RAS Institute of Molecular Genetics, 2 Kurchatova Sq., Moscow 123182, Russian Federation
| | - Regina R Miftakhova
- Kazan Federal University, 18 Kremlevsakaya St., Kazan 420008, Russian Federation
| | - Dmitry O Zharkov
- Novosibirsk State University, 2 Pirogova St., Novosibirsk 630090, Russian Federation.,SB RAS Institute of Chemical Biology and Fu ndamental Medicine, 8 Lavrentieva Ave., Novosibirsk 630090, Russian Federation
| |
Collapse
|
6
|
Zhang K, Keymeulen S, Nelson R, Tong TR, Yuan YC, Yun X, Liu Z, Lopez J, Raz DJ, Kim JY. Overexpression of Flap Endonuclease 1 Correlates with Enhanced Proliferation and Poor Prognosis of Non-Small-Cell Lung Cancer. THE AMERICAN JOURNAL OF PATHOLOGY 2017; 188:242-251. [PMID: 29037854 DOI: 10.1016/j.ajpath.2017.09.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 09/14/2017] [Accepted: 09/21/2017] [Indexed: 01/31/2023]
Abstract
Flap endonuclease 1 (FEN1) plays a crucial role in both DNA replication and damage repair. In this study, FEN1 expression and its clinical-pathologic significance in non-small-cell lung cancer (NSCLC) was investigated. Quantitative RT-PCR and immunohistochemistry analysis identified that both FEN1 mRNA and protein were highly overexpressed in about 36% of 136 cancer tissues compared to adjacent tissues, in which FEN1 was generally undetectable. Notably, patients with FEN1-overexpressed cancers were prone to have poor differentiation and poor prognosis. A strong positive correlation between the levels of FEN1 and Ki-67 staining was identified in these NSCLC tissues (r = 0.485), suggesting overexpressed FEN1 conferred a proliferative advantage to NSCLC. Furthermore, knockdown of FEN1 resulted in G1/S or G2/M phase cell cycle arrest and suppressed in vitro cellular proliferation in NSCLC cancer cells. Consistently, a selective FEN1 inhibitor was shown to effectively inhibit cellular proliferation of NSCLC cells in a dose-dependent manner. Additionally, knockdown of FEN1 significantly attenuated homologous DNA repair efficiency and enhanced cytotoxic effects of cisplatin in NSCLC cells. Taken together, these findings have indicated that overexpressed FEN1 represents a prognostic biomarker and potential therapeutic target for NSCLC treatment, which warrants further study.
Collapse
Affiliation(s)
- Keqiang Zhang
- Division of Thoracic Surgery, City of Hope National Medical Center, Duarte, California.
| | - Sawa Keymeulen
- Division of Thoracic Surgery, City of Hope National Medical Center, Duarte, California
| | - Rebecca Nelson
- Division of Biostatistics, City of Hope National Medical Center, Duarte, California
| | - Tommy R Tong
- Department of Pathology, City of Hope National Medical Center, Duarte, California
| | - Yate-Ching Yuan
- Bioinformatics Core Facility, Department of Molecular Medicine, City of Hope National Medical Center, Duarte, California
| | - Xinwei Yun
- Division of Thoracic Surgery, City of Hope National Medical Center, Duarte, California
| | - Zheng Liu
- Bioinformatics Core Facility, Department of Molecular Medicine, City of Hope National Medical Center, Duarte, California
| | - Joshua Lopez
- Division of Thoracic Surgery, City of Hope National Medical Center, Duarte, California
| | - Dan J Raz
- Division of Thoracic Surgery, City of Hope National Medical Center, Duarte, California
| | - Jae Y Kim
- Division of Thoracic Surgery, City of Hope National Medical Center, Duarte, California.
| |
Collapse
|
7
|
Ward TA, McHugh PJ, Durant ST. Small molecule inhibitors uncover synthetic genetic interactions of human flap endonuclease 1 (FEN1) with DNA damage response genes. PLoS One 2017. [PMID: 28628639 PMCID: PMC5476263 DOI: 10.1371/journal.pone.0179278] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Flap endonuclease 1 (FEN1) is a structure selective endonuclease required for proficient DNA replication and the repair of DNA damage. Cellularly active inhibitors of this enzyme have previously been shown to induce a DNA damage response and, ultimately, cell death. High-throughput screens of human cancer cell-lines identify colorectal and gastric cell-lines with microsatellite instability (MSI) as enriched for cellular sensitivity to N-hydroxyurea series inhibitors of FEN1, but not the PARP inhibitor olaparib or other inhibitors of the DNA damage response. This sensitivity is due to a synthetic lethal interaction between FEN1 and MRE11A, which is often mutated in MSI cancers through instabilities at a poly(T) microsatellite repeat. Disruption of ATM is similarly synthetic lethal with FEN1 inhibition, suggesting that disruption of FEN1 function leads to the accumulation of DNA double-strand breaks. These are likely a result of the accumulation of aberrant replication forks, that accumulate as a consequence of a failure in Okazaki fragment maturation, as inhibition of FEN1 is toxic in cells disrupted for the Fanconi anemia pathway and post-replication repair. Furthermore, RAD51 foci accumulate as a consequence of FEN1 inhibition and the toxicity of FEN1 inhibitors increases in cells disrupted for the homologous recombination pathway, suggesting a role for homologous recombination in the resolution of damage induced by FEN1 inhibition. Finally, FEN1 appears to be required for the repair of damage induced by olaparib and cisplatin within the Fanconi anemia pathway, and may play a role in the repair of damage associated with its own disruption.
Collapse
Affiliation(s)
- Thomas A. Ward
- AstraZeneca, Innovative Medicines and Early Development Biotech Unit, Oncology Bioscience, Alderley Park, Macclesfield, Cheshire, United Kingdom
- Department of Oncology, MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
- * E-mail: (TAW); (STD)
| | - Peter J. McHugh
- Department of Oncology, MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
| | - Stephen T. Durant
- AstraZeneca, Innovative Medicines and Early Development Biotech Unit, Oncology Bioscience, Alderley Park, Macclesfield, Cheshire, United Kingdom
- AstraZeneca, Innovative Medicines and Early Development Biotech Unit, Oncology Bioscience, Little Chesterford, Cambridge, United Kingdom
- * E-mail: (TAW); (STD)
| |
Collapse
|
8
|
Transcriptome analysis of a wild bird reveals physiological responses to the urban environment. Sci Rep 2017; 7:44180. [PMID: 28290496 PMCID: PMC5349542 DOI: 10.1038/srep44180] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 02/06/2017] [Indexed: 12/17/2022] Open
Abstract
Identifying the molecular basis of environmentally induced phenotypic variation presents exciting opportunities for furthering our understanding of how ecological processes and the environment can shape the phenotype. Urban and rural environments present free-living organisms with different challenges and opportunities, which have marked consequences for the phenotype, yet little is known about responses at the molecular level. We characterised transcriptomes from an urban and a rural population of great tits Parus major, demonstrating striking differences in gene expression profiles in both blood and liver tissues. Differentially expressed genes had functions related to immune and inflammatory responses, detoxification, protection against oxidative stress, lipid metabolism, and regulation of gene expression. Many genes linked to stress responses were expressed at higher levels in the urban birds, in accordance with our prediction that urban animals are exposed to greater environmental stress. This is one of the first studies to reveal transcriptional differences between urban- and rural-dwelling animals and suggests an important role for epigenetics in mediating environmentally induced physiological variation. The study provides valuable resources for developing further in-depth studies of the mechanisms driving phenotypic variation in the urban context at larger spatial and temporal scales.
Collapse
|
9
|
Zhang J, Xie S, Zhu JK, Gong Z. Requirement for flap endonuclease 1 (FEN1) to maintain genomic stability and transcriptional gene silencing in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 87:629-40. [PMID: 27231839 PMCID: PMC5508578 DOI: 10.1111/tpj.13224] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 05/17/2016] [Accepted: 05/25/2016] [Indexed: 05/02/2023]
Abstract
As a central component in the maturation of Okazaki fragments, flap endonuclease 1 (FEN1) removes the 5'-flap and maintains genomic stability. Here, FEN1 was cloned as a suppressor of transcriptional gene silencing (TGS) from a forward genetic screen. FEN1 is abundant in the root and shoot apical meristems and FEN1-GFP shows a nucleolus-localized signal in tobacco cells. The Arabidopsis fen1-1 mutant is hypersensitive to methyl methanesulfonate and shows reduced telomere length. Interestingly, genome-wide chromatin immunoprecipitation and RNA sequencing results demonstrate that FEN1 mutation leads to a decrease in the level of H3K27me3 and an increase in the expression of a subset of genes marked with H3K27me3. Overall, these results uncover a role for FEN1 in mediating TGS as well as maintaining genome stability in Arabidopsis.
Collapse
Affiliation(s)
- Jixiang Zhang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Shaojun Xie
- Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, 47906, USA
| | - Jian-Kang Zhu
- Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, 47906, USA
| | - Zhizhong Gong
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
| |
Collapse
|
10
|
Jiang L, Wu X, He F, Liu Y, Hu X, Takeda S, Qing Y. Genetic Evidence for Genotoxic Effect of Entecavir, an Anti-Hepatitis B Virus Nucleotide Analog. PLoS One 2016; 11:e0147440. [PMID: 26800464 PMCID: PMC4723259 DOI: 10.1371/journal.pone.0147440] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 01/04/2016] [Indexed: 02/05/2023] Open
Abstract
Nucleoside analogues (NAs) have been the most frequently used treatment option for chronic hepatitis B patients. However, they may have genotoxic potentials due to their interference with nucleic acid metabolism. Entecavir, a deoxyguanosine analog, is one of the most widely used oral antiviral NAs against hepatitis B virus. It has reported that entecavir gave positive responses in both genotoxicity and carcinogenicity assays. However the genotoxic mechanism of entecavir remains elusive. To evaluate the genotoxic mechanisms, we analyzed the effect of entecavir on a panel of chicken DT40 B-lymphocyte isogenic mutant cell line deficient in DNA repair and damage tolerance pathways. Our results showed that Parp1-/- mutant cells defective in single-strand break (SSB) repair were the most sensitive to entecavir. Brca1-/-, Ubc13-/- and translesion-DNA-synthesis deficient cells including Rad18-/- and Rev3-/- were hypersensitive to entecavir. XPA-/- mutant deficient in nucleotide excision repair was also slightly sensitive to entecavir. γ-H2AX foci forming assay confirmed the existence of DNA damage by entecavir in Parp1-/-, Rad18-/- and Brca1-/- mutants. Karyotype assay further showed entecavir-induced chromosomal aberrations, especially the chromosome gaps in Parp1-/-, Brca1-/-, Rad18-/- and Rev3-/- cells when compared with wild-type cells. These genetic comprehensive studies clearly identified the genotoxic potentials of entecavir and suggested that SSB and postreplication repair pathways may suppress entecavir-induced genotoxicity.
Collapse
Affiliation(s)
- Lei Jiang
- Department of Pharmacology, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Xiaohua Wu
- Regenerative Medicine Research Center, and State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Fang He
- Center of Infectious Diseases, Division of Molecular Biology of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Ying Liu
- Department of Pharmacology, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Xiaoqing Hu
- Department of Pharmacology, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Shunichi Takeda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, 606–8501, Japan
| | - Yong Qing
- Department of Pharmacology, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, 610041, China
| |
Collapse
|
11
|
Kametani Y, Takahata C, Narita T, Tanaka K, Iwai S, Kuraoka I. FEN1 participates in repair of the 5'-phosphotyrosyl terminus of DNA single-strand breaks. Carcinogenesis 2015; 37:56-62. [PMID: 26581212 DOI: 10.1093/carcin/bgv159] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 11/07/2015] [Indexed: 11/14/2022] Open
Abstract
Etoposide is a widely used anticancer drug and a DNA topoisomerase II (Top2) inhibitor. Etoposide produces Top2-attached single-strand breaks (Top2-SSB complex) and double-strand breaks (Top2-DSB complex) that are thought to induce cell death in tumor cells. The Top2-SSB complex is more abundant than the Top2-DSB complex. Human tyrosyl-DNA phosphodiesterase 2 (TDP2) is required for efficient repair of Top2-DSB complexes. However, the identities of the proteins involved in the repair of Top2-SSB complexes are unknown, although yeast genetic data indicate that 5' to 3' structure-specific DNA endonuclease activity is required for alternative repair of Top2 DNA damage. In this study, we purified a flap endonuclease 1 (FEN1) and xeroderma pigmentosum group G protein (XPG) in the 5' to 3' structure-specific DNA endonuclease family and synthesized single-strand break DNA substrates containing a 5'-phoshotyrosyl bond, mimicking the Top2-SSB complex. We found that FEN1 and XPG did not remove the 5'-phoshotyrosyl bond-containing DSB substrates but removed the 5'-phoshotyrosyl bond-containing SSB substrates. Under DNA repair conditions, FEN1 efficiently repaired the 5'-phoshotyrosyl bond-containing SSB substrates in the presence of DNA ligase and DNA polymerase. Therefore, FEN1 may play an important role in the repair of Top2-SSB complexes in etoposide-treated cells.
Collapse
Affiliation(s)
- Yukiko Kametani
- Graduate School of Engineering Science, Osaka University Graduate School of Engineering Science, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan and
| | - Chiaki Takahata
- Graduate School of Engineering Science, Osaka University Graduate School of Engineering Science, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan and
| | - Takashi Narita
- Laboratories for Organismal Biosystems, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Kiyoji Tanaka
- Laboratories for Organismal Biosystems, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Shigenori Iwai
- Graduate School of Engineering Science, Osaka University Graduate School of Engineering Science, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan and
| | - Isao Kuraoka
- Graduate School of Engineering Science, Osaka University Graduate School of Engineering Science, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan and
| |
Collapse
|
12
|
Tada K, Kobayashi M, Takiuchi Y, Iwai F, Sakamoto T, Nagata K, Shinohara M, Io K, Shirakawa K, Hishizawa M, Shindo K, Kadowaki N, Hirota K, Yamamoto J, Iwai S, Sasanuma H, Takeda S, Takaori-Kondo A. Abacavir, an anti-HIV-1 drug, targets TDP1-deficient adult T cell leukemia. SCIENCE ADVANCES 2015; 1:e1400203. [PMID: 26601161 PMCID: PMC4640626 DOI: 10.1126/sciadv.1400203] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 03/29/2015] [Indexed: 05/07/2023]
Abstract
Adult T cell leukemia (ATL) is an aggressive T cell malignancy caused by human T cell leukemia virus type 1 (HTLV-1) and has a poor prognosis. We analyzed the cytotoxic effects of various nucleoside analog reverse transcriptase inhibitors (NRTIs) for HIV-1 on ATL cells and found that abacavir potently and selectively kills ATL cells. Although NRTIs have minimal genotoxicities on host cells, the therapeutic concentration of abacavir induced numerous DNA double-strand breaks (DSBs) in the chromosomal DNA of ATL cells. DSBs persisted over time in ATL cells but not in other cell lines, suggesting impaired DNA repair. We found that the reduced expression of tyrosyl-DNA phosphodiesterase 1 (TDP1), a repair enzyme, is attributable to the cytotoxic effect of abacavir on ATL cells. We also showed that TDP1 removes abacavir from DNA ends in vitro. These results suggest a model in which ATL cells with reduced TDP1 expression are unable to excise abacavir incorporated into genomic DNA, leading to irreparable DSBs. On the basis of the above mechanism, we propose abacavir as a promising chemotherapeutic agent for ATL.
Collapse
Affiliation(s)
- Kohei Tada
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawaracho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Masayuki Kobayashi
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawaracho, Sakyo-ku, Kyoto 606-8507, Japan
- Corresponding author: E-mail: (M.K.); (A.T.-K.)
| | - Yoko Takiuchi
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawaracho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Fumie Iwai
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawaracho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Takashi Sakamoto
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawaracho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Kayoko Nagata
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawaracho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Masanobu Shinohara
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawaracho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Katsuhiro Io
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawaracho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Kotaro Shirakawa
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawaracho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Masakatsu Hishizawa
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawaracho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Keisuke Shindo
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawaracho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Norimitsu Kadowaki
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawaracho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Kouji Hirota
- Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo 192-0397, Japan
| | - Junpei Yamamoto
- Division of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Shigenori Iwai
- Division of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Hiroyuki Sasanuma
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | - Shunichi Takeda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | - Akifumi Takaori-Kondo
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawaracho, Sakyo-ku, Kyoto 606-8507, Japan
- Corresponding author: E-mail: (M.K.); (A.T.-K.)
| |
Collapse
|
13
|
Mohiuddin, Keka IS, Evans TJ, Hirota K, Shimizu H, Kono K, Takeda S, Hirano S. A novel genotoxicity assay of carbon nanotubes using functional macrophage receptor with collagenous structure (MARCO)-expressing chicken B lymphocytes. Arch Toxicol 2013; 88:145-60. [PMID: 23963510 DOI: 10.1007/s00204-013-1084-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 06/20/2013] [Indexed: 01/09/2023]
Abstract
Although carbon nanotubes (CNTs) are promising nanomaterials, their potential carcinogenicity is a major concern. We previously established a genetic method of analyzing genotoxicity of chemical compounds, where we evaluated their cytotoxic effect on the DT40 lymphoid cell line comparing DNA-repair-deficient isogenic clones with parental wild-type cells. However, application of our DT40 system for the cytotoxic and genotoxic evaluation of nanomaterials seemed to be difficult, because DT40 cells only poorly internalized nanoparticles. To solve this problem, we have constructed a chimeric gene encoding a trans-membrane receptor consisting of the 5' region of the transferrin receptor (TR) gene (to facilitate internalization of nanoparticles) and the 3' region of the macrophage receptor with collagenous structure (MARCO) gene (which is a receptor for environmental particles). We expressed the resulting MARCO-TR chimeric receptor on DNA-repair-proficient wild-type cells and mutants deficient in base excision repair (FEN1 (-/-)) and translesion DNA synthesis (REV3 (-/-)). We demonstrated that the chimera mediates uptake of particles such as fluorescence-tagged polystyrene particles and multi-walled carbon nanotubes (MWCNTs), with very poor uptake of those particles by DT40 cells not expressing the chimera. MWCNTs were cytotoxic and this effect was greater in FEN1 (-/-)and REV3 (-/-) cells than in wild-type cells. Furthermore, MWCNTs induced greater oxidative damage (measured as 8-OH-dG formation) and a larger number of mitotic chromosomal aberrations in repair-deficient cells compared to repair-proficient cells. Taken together, our novel assay system using the chimeric receptor-expressing DT40 cells provides a sensitive method to screen for genotoxicity of CNTs and possibly other nanomaterials.
Collapse
Affiliation(s)
- Mohiuddin
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Patel N, Atack JM, Finger LD, Exell JC, Thompson P, Tsutakawa S, Tainer JA, Williams DM, Grasby JA. Flap endonucleases pass 5'-flaps through a flexible arch using a disorder-thread-order mechanism to confer specificity for free 5'-ends. Nucleic Acids Res 2012; 40:4507-19. [PMID: 22319208 PMCID: PMC3378889 DOI: 10.1093/nar/gks051] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Revised: 01/09/2012] [Accepted: 01/13/2012] [Indexed: 11/13/2022] Open
Abstract
Flap endonucleases (FENs), essential for DNA replication and repair, recognize and remove RNA or DNA 5'-flaps. Related to FEN specificity for substrates with free 5'-ends, but controversial, is the role of the helical arch observed in varying conformations in substrate-free FEN structures. Conflicting models suggest either 5'-flaps thread through the arch, which when structured can only accommodate single-stranded (ss) DNA, or the arch acts as a clamp. Here we show that free 5'-termini are selected using a disorder-thread-order mechanism. Adding short duplexes to 5'-flaps or 3'-streptavidin does not markedly impair the FEN reaction. In contrast, reactions of 5'-streptavidin substrates are drastically slowed. However, when added to premixed FEN and 5'-biotinylated substrate, streptavidin is not inhibitory and complexes persist after challenge with unlabelled competitor substrate, regardless of flap length or the presence of a short duplex. Cross-linked flap duplexes that cannot thread through the structured arch react at modestly reduced rate, ruling out mechanisms involving resolution of secondary structure. Combined results explain how FEN avoids cutting template DNA between Okazaki fragments and link local FEN folding to catalysis and specificity: the arch is disordered when flaps are threaded to confer specificity for free 5'-ends, with subsequent ordering of the arch to catalyze hydrolysis.
Collapse
Affiliation(s)
- Nikesh Patel
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute, University of Sheffield, Sheffield S3 7HF, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Yamamoto KN, Hirota K, Kono K, Takeda S, Sakamuru S, Xia M, Huang R, Austin CP, Witt KL, Tice RR. Characterization of environmental chemicals with potential for DNA damage using isogenic DNA repair-deficient chicken DT40 cell lines. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2011; 52:547-61. [PMID: 21538559 PMCID: PMC3278799 DOI: 10.1002/em.20656] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 03/02/2011] [Indexed: 05/23/2023]
Abstract
Included among the quantitative high throughput screens (qHTS) conducted in support of the US Tox21 program are those being evaluated for the detection of genotoxic compounds. One such screen is based on the induction of increased cytotoxicity in seven isogenic chicken DT40 cell lines deficient in DNA repair pathways compared to the parental DNA repair-proficient cell line. To characterize the utility of this approach for detecting genotoxic compounds and identifying the type(s) of DNA damage induced, we evaluated nine of 42 compounds identified as positive for differential cytotoxicity in qHTS (actinomycin D, adriamycin, alachlor, benzotrichloride, diglycidyl resorcinol ether, lovastatin, melphalan, trans-1,4-dichloro-2-butene, tris(2,3-epoxypropyl)isocyanurate) and one non-cytotoxic genotoxic compound (2-aminothiamine) for (1) clastogenicity in mutant and wild-type cells; (2) the comparative induction of γH2AX positive foci by melphalan; (3) the extent to which a 72-hr exposure duration increased assay sensitivity or specificity; (4) the use of 10 additional DT40 DNA repair-deficient cell lines to better analyze the type(s) of DNA damage induced; and (5) the involvement of reactive oxygen species in the induction of DNA damage. All compounds but lovastatin and 2-aminothiamine were more clastogenic in at least one DNA repair-deficient cell line than the wild-type cells. The differential responses across the various DNA repair-deficient cell lines provided information on the type(s) of DNA damage induced. The results demonstrate the utility of this DT40 screen for detecting genotoxic compounds, for characterizing the nature of the DNA damage, and potentially for analyzing mechanisms of mutagenesis.
Collapse
Affiliation(s)
- Kimiyo N Yamamoto
- Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo, Japan.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Tsutakawa SE, Classen S, Chapados BR, Arvai AS, Finger LD, Guenther G, Tomlinson CG, Thompson P, Sarker AH, Shen B, Cooper PK, Grasby JA, Tainer JA. Human flap endonuclease structures, DNA double-base flipping, and a unified understanding of the FEN1 superfamily. Cell 2011; 145:198-211. [PMID: 21496641 DOI: 10.1016/j.cell.2011.03.004] [Citation(s) in RCA: 210] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 01/11/2011] [Accepted: 03/01/2011] [Indexed: 11/17/2022]
Abstract
Flap endonuclease (FEN1), essential for DNA replication and repair, removes RNA and DNA 5' flaps. FEN1 5' nuclease superfamily members acting in nucleotide excision repair (XPG), mismatch repair (EXO1), and homologous recombination (GEN1) paradoxically incise structurally distinct bubbles, ends, or Holliday junctions, respectively. Here, structural and functional analyses of human FEN1:DNA complexes show structure-specific, sequence-independent recognition for nicked dsDNA bent 100° with unpaired 3' and 5' flaps. Above the active site, a helical cap over a gateway formed by two helices enforces ssDNA threading and specificity for free 5' ends. Crystallographic analyses of product and substrate complexes reveal that dsDNA binding and bending, the ssDNA gateway, and double-base unpairing flanking the scissile phosphate control precise flap incision by the two-metal-ion active site. Superfamily conserved motifs bind and open dsDNA; direct the target region into the helical gateway, permitting only nonbase-paired oligonucleotides active site access; and support a unified understanding of superfamily substrate specificity.
Collapse
Affiliation(s)
- Susan E Tsutakawa
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Jagannathan I, Pepenella S, Hayes JJ. Activity of FEN1 endonuclease on nucleosome substrates is dependent upon DNA sequence but not flap orientation. J Biol Chem 2011; 286:17521-9. [PMID: 21454907 DOI: 10.1074/jbc.m111.229658] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We demonstrated previously that human FEN1 endonuclease, an enzyme involved in excising single-stranded DNA flaps that arise during Okazaki fragment processing and base excision repair, cleaves model flap substrates assembled into nucleosomes. Here we explore the effect of flap orientation with respect to the surface of the histone octamer on nucleosome structure and FEN1 activity in vitro. We find that orienting the flap substrate toward the histone octamer does not significantly alter the rotational orientation of two different nucleosome positioning sequences on the surface of the histone octamer but does cause minor perturbation of nucleosome structure. Surprisingly, flaps oriented toward the nucleosome surface are accessible to FEN1 cleavage in nucleosomes containing the Xenopus 5S positioning sequence. In contrast, neither flaps oriented toward nor away from the nucleosome surface are cleaved by the enzyme in nucleosomes containing the high-affinity 601 nucleosome positioning sequence. The data are consistent with a model in which sequence-dependent motility of DNA on the nucleosome is a major determinant of FEN1 activity. The implications of these findings for the activity of FEN1 in vivo are discussed.
Collapse
Affiliation(s)
- Indu Jagannathan
- Department of Biochemistry and Biophysics, University of Rochester, Rochester, New York 14642, USA
| | | | | |
Collapse
|
18
|
Dorjsuren D, Kim D, Maloney DJ, Wilson DM, Simeonov A. Complementary non-radioactive assays for investigation of human flap endonuclease 1 activity. Nucleic Acids Res 2010; 39:e11. [PMID: 21062821 PMCID: PMC3025571 DOI: 10.1093/nar/gkq1082] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
FEN1, a key participant in DNA replication and repair, is the major human flap endonuclease that recognizes and cleaves flap DNA structures. Deficiencies in FEN1 function or deletion of the fen1 gene have profound biological effects, including the suppression of repair of DNA damage incurred from the action of various genotoxic agents. Given the importance of FEN1 in resolving abnormal DNA structures, inhibitors of the enzyme carry a potential as enhancers of DNA-interactive anticancer drugs. To facilitate the studies of FEN1 activity and the search for novel inhibitors, we developed a pair of complementary-readout homogeneous assays utilizing fluorogenic donor/quencher and AlphaScreen chemiluminescence strategies. A previously reported FEN1 inhibitor 3-hydroxy-5-methyl-1-phenylthieno[2,3-d]pyrimidine-2,4(1H,3H)-dione displayed equal potency in the new assays, in agreement with its published IC50. The assays were optimized to a low 4 µl volume and used to investigate a set of small molecules, leading to the identification of previously-unreported FEN1 inhibitors, among which aurintricarboxylic acid and NSC-13755 (an arylstibonic derivative) displayed submicromolar potency (average IC50 of 0.59 and 0.93 µM, respectively). The availability of these simple complementary assays obviates the need for undesirable radiotracer-based assays and should facilitate efforts to develop novel inhibitors for this key biological target.
Collapse
Affiliation(s)
- Dorjbal Dorjsuren
- NIH Chemical Genomics Center, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-3370, USA
| | | | | | | | | |
Collapse
|
19
|
Chastain PD, Nakamura J, Rao S, Chu H, Ibrahim JG, Swenberg JA, Kaufman DG. Abasic sites preferentially form at regions undergoing DNA replication. FASEB J 2010; 24:3674-80. [PMID: 20511393 DOI: 10.1096/fj.09-145276] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We investigated whether apurinic/apyrimidinic (AP/abasic) sites were more frequent in regions of DNA replication in cells and whether their number increased during oxidative stress. DNA fiber spreading and fluorescent immunostaining were used to detect areas of DNA replication and sites of AP lesions in extended DNA fibers. The distribution of AP sites was determined in DNA fibers from vertebrate cells maintained under normal culture conditions or stressed with exogenous H(2)O(2). AP lesions per unit length were enumerated in bulk DNA or at replication sites. The background density of AP sites in DNA fibers was 5.4 AP sites/10(6) nt, while newly replicated DNA contained 12.9 AP sites/10(6) nt. In cells exposed to 20 μM H(2)O(2), AP sites in newly replicated DNA increased to 20.8/10(6) nt. Determinations of AP site density in bulk DNA by fiber analysis or standard slot blot assays agreed to within 10%. Our findings show that the fiber assay not only accurately determines the frequency of AP sites but also shows their distribution. They also reveal that there is increased susceptibility to oxidative damage in DNA regions undergoing replication, which may explain the previously observed clustering of AP sites.
Collapse
Affiliation(s)
- Paul D Chastain
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7525, USA.
| | | | | | | | | | | | | |
Collapse
|
20
|
Asagoshi K, Tano K, Chastain PD, Adachi N, Sonoda E, Kikuchi K, Koyama H, Nagata K, Kaufman DG, Takeda S, Wilson SH, Watanabe M, Swenberg JA, Nakamura J. FEN1 functions in long patch base excision repair under conditions of oxidative stress in vertebrate cells. Mol Cancer Res 2010; 8:204-15. [PMID: 20145043 DOI: 10.1158/1541-7786.mcr-09-0253] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
From in vitro studies, flap endonuclease 1 (FEN1) has been proposed to play a role in the long patch (LP) base excision repair (BER) subpathway. Yet the role of FEN1 in BER in the context of the living vertebrate cell has not been thoroughly explored. In the present study, we cloned a DT40 chicken cell line with a deletion in the FEN1 gene and found that these FEN1-deficient cells exhibited hypersensitivity to H(2)O(2). This oxidant produces genotoxic lesions that are repaired by BER, suggesting that the cells have a deficiency in BER affecting survival. In experiments with extracts from the isogenic FEN1 null and wild-type cell lines, the LP-BER activity of FEN1 null cells was deficient, whereas repair by the single-nucleotide BER subpathway was normal. Other consequences of the FEN1 deficiency were also evaluated. These results illustrate that FEN1 plays a role in LP-BER in higher eukaryotes, presumably by processing the flap-containing intermediates of BER.
Collapse
Affiliation(s)
- Kenjiro Asagoshi
- Laboratory of Structural Biology, NIEHS, NIH, Research Triangle Park, North Carolina, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Speina E, Dawut L, Hedayati M, Wang Z, May A, Schwendener S, Janscak P, Croteau DL, Bohr VA. Human RECQL5beta stimulates flap endonuclease 1. Nucleic Acids Res 2010; 38:2904-16. [PMID: 20081208 PMCID: PMC2875029 DOI: 10.1093/nar/gkp1217] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Human RECQL5 is a member of the RecQ helicase family which is implicated in genome maintenance. Five human members of the family have been identified; three of them, BLM, WRN and RECQL4 are associated with elevated cancer risk. RECQL1 and RECQL5 have not been linked to any human disorder yet; cells devoid of RECQL1 and RECQL5 display increased chromosomal instability. Here, we report the physical and functional interaction of the large isomer of RECQL5, RECQL5β, with the human flap endonuclease 1, FEN1, which plays a critical role in DNA replication, recombination and repair. RECQL5β dramatically stimulates the rate of FEN1 cleavage of flap DNA substrates. Moreover, we show that RECQL5β and FEN1 interact physically and co-localize in the nucleus in response to DNA damage. Our findings, together with the previous literature on WRN, BLM and RECQL4’s stimulation of FEN1, suggests that the ability of RecQ helicases to stimulate FEN1 may be a general feature of this class of enzymes. This could indicate a common role for the RecQ helicases in the processing of oxidative DNA damage.
Collapse
Affiliation(s)
- Elzbieta Speina
- National Institute on Aging, National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Iiizumi S, Kurosawa A, So S, Ishii Y, Chikaraishi Y, Ishii A, Koyama H, Adachi N. Impact of non-homologous end-joining deficiency on random and targeted DNA integration: implications for gene targeting. Nucleic Acids Res 2008; 36:6333-42. [PMID: 18835848 PMCID: PMC2577324 DOI: 10.1093/nar/gkn649] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In higher animal cells, the principal limitation of gene-targeting technology is the extremely low efficiency of targeted integration, which occurs three to four orders of magnitude less frequently than random integration. Assuming that random integration mechanistically involves non-homologous end-joining (NHEJ), inactivation of this pathway should reduce random integration and may enhance gene targeting. To test this possibility, we examined the frequencies of random and targeted integration in NHEJ-deficient chicken DT40 and human Nalm-6 cell lines. As expected, loss of NHEJ resulted in drastically reduced random integration in DT40 cells. Unexpectedly, however, this was not the case for Nalm-6 cells, indicating that NHEJ is not the sole mechanism of random integration. Nevertheless, we present evidence that NHEJ inactivation can lead to enhanced gene targeting through a reduction of random integration and/or an increase in targeted integration by homologous recombination. Most intriguingly, our results show that, in the absence of functional NHEJ, random integration of targeting vectors occurs more frequently than non-targeting vectors (harboring no or little homology to the host genome), implying that suppression of NHEJ-independent random integration events is needed to greatly enhance gene targeting in animal cells.
Collapse
Affiliation(s)
- Susumu Iiizumi
- International Graduate School of Arts and Sciences and Kihara Institute for Biological Research, Yokohama City University, Yokohama, Japan
| | | | | | | | | | | | | | | |
Collapse
|
23
|
Moe SE, Sorbo JG, Holen T. Huntingtin triplet-repeat locus is stable under long-term Fen1 knockdown in human cells. J Neurosci Methods 2008; 171:233-8. [DOI: 10.1016/j.jneumeth.2008.03.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Revised: 03/16/2008] [Accepted: 03/20/2008] [Indexed: 11/29/2022]
|
24
|
Ruymgaart AP, Heater SJ, Oehlers LP, Rains JD, Walter RB. Characterization and purification of flap endonuclease-1 (xiFEN-1) from Xiphophorus maculatus. Zebrafish 2008; 1:273-85. [PMID: 18248237 DOI: 10.1089/zeb.2004.1.273] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The cloning, gene structure, and expression of flap endonuclease-1 (xiFEN1) from Xiphophorus maculates are presented. The xiFEN1 gene structure was found to include 8 exons and 7 introns. The Xiphophorus FEN1 cDNA sequence contained an open reading frame that encoded a 380 amino acid protein with a predicted mass of 43 kDa. The intact FEN1 cDNA was subcloned into a bacterial expression vector (pET101-xiFEN1ct) and recombinant xiFEN1 enzyme purified from E. colicell extracts. The pET101-xiFEN1ct translation product was a 3' fusion protein with a ~3 kDa vector-encoded carboxy terminal extension designed to facilitate protein recognition and purification. The xiFEN1 fusion protein was purified and its amino acid sequence verified by Western blot analysis and tryptic peptide mass fingerprinting. The purified recombinant protein was assessed for enzyme specificity using several different oligonucleotide substrates having select flap overhangs. Also reported are Michaelis steady state kinetic values of enzymatic activity for the xiFEN1 directly compared with human FEN1 activity. xiFEN1 displayed a five-fold greater Km and six-fold lower catalytic efficiency (kcat/Km) than observed for the hFEN1.
Collapse
Affiliation(s)
- Arnold P Ruymgaart
- Molecular Biosciences Research Group, Department of Chemistry and Biochemistry, Texas State University, San Marcos, Texas 78666, USA
| | | | | | | | | |
Collapse
|
25
|
Sidorova JM, Li N, Folch A, Monnat RJ. The RecQ helicase WRN is required for normal replication fork progression after DNA damage or replication fork arrest. Cell Cycle 2008; 7:796-807. [PMID: 18250621 DOI: 10.4161/cc.7.6.5566] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Werner syndrome is an autosomal recessive genetic instability and cancer predisposition syndrome with features of premature aging. Several lines of evidence have suggested that the Werner syndrome protein WRN plays a role in DNA replication and S-phase progression. In order to define the exact role of WRN in genomic replication we examined cell cycle kinetics during normal cell division and after methyl-methane-sulfonate (MMS) DNA damage or hydroxyurea (HU)-mediated replication arrest following acute depletion of WRN from human fibroblasts. Loss of WRN markedly extended the time cells needed to complete the cell cycle after either of these genotoxic treatments. Moreover, replication track analysis of individual, stretched DNA fibers showed that WRN depletion significantly reduced the speed at which replication forks elongated in vivo after MMS or HU treatment. These results establish the importance of WRN during genomic replication and indicate that WRN acts to facilitate fork progression after DNA damage or replication arrest. The data provide a mechanistic basis for a better understanding of WRN-mediated maintenance of genomic stability and for predicting the outcomes of DNA-targeting chemotherapy in several adult cancers that silence WRN expression.
Collapse
Affiliation(s)
- Julia M Sidorova
- Department of Pathology, University of Washington, Seattle, Washington 98195-7705, USA.
| | | | | | | |
Collapse
|
26
|
Casta LJ, Buguliskis JS, Matsumoto Y, Taraschi TF. Expression and biochemical characterization of the Plasmodium falciparum DNA repair enzyme, flap endonuclease-1 (PfFEN-1). Mol Biochem Parasitol 2007; 157:1-12. [PMID: 17928073 DOI: 10.1016/j.molbiopara.2007.08.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 08/24/2007] [Accepted: 08/27/2007] [Indexed: 11/29/2022]
Abstract
Flap endonuclease-1 (FEN-1) is a structure-specific endonuclease that is critical for the resolution of single-stranded DNA flap intermediates that form during long patch DNA base excision repair (BER). This investigation reports that Plasmodium species encode FEN-1 homologs. Protein sequence analysis revealed the N and I domains of Plasmodium falciparum (PfFEN-1) and Plasmodium yoelii (PyFEN-1) to be homologous to FEN-1 from other species. However, each possessed an extended C domain which had limited homology to apicomplexan FEN-1s and no homology to eukaryotic FEN-1s. A conserved proliferating cell nuclear antigen (PCNA)-binding site was identified at an internal location rather than the extreme C-terminal location typically seen in FEN-1 from other organisms. The endonuclease and exonuclease activities of PfFEN-1 and PyFEN-1 were investigated using recombinant protein produced in Escherichia coli. Pf and PyFEN-1 possessed DNA structure-specific flap endonuclease and 5'-->3' exonuclease activities, similar to FEN-1s from other species. Endonuclease activity was stimulated by Mg(2+) or Mn(2+) and inhibited by monovalent ions (>20.0 mM). A PfFEN-1 C-terminal truncation mutant lacking the terminal 250 amino acids (PfFEN-1DeltaC) had endonuclease activity that was approximately 130-fold greater (k(cat)=1.2x10(-1)) than full-length PfFEN-1 (k(cat)=9.1x10(-4)) or approximately 240-fold greater than PyFEN-1 (k(cat)=4.9x10(-4)) in vitro. PfFEN-1 generated a nicked DNA substrate that was ligated by recombinant Pf DNA Ligase I (PfLigI) using an in vitro DNA repair assay. Plasmodium FEN-1s have enzymatic activities similar to other species but contain extended C-termini and a more internally located PCNA-binding site.
Collapse
Affiliation(s)
- Louis J Casta
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107-6731, USA
| | | | | | | |
Collapse
|
27
|
Kaina B, Christmann M, Naumann S, Roos WP. MGMT: key node in the battle against genotoxicity, carcinogenicity and apoptosis induced by alkylating agents. DNA Repair (Amst) 2007; 6:1079-99. [PMID: 17485253 DOI: 10.1016/j.dnarep.2007.03.008] [Citation(s) in RCA: 444] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
O(6)-methylguanine-DNA methyltransferase (MGMT) plays a crucial role in the defense against alkylating agents that generate, among other lesions, O(6)-alkylguanine in DNA (collectively termed O(6)-alkylating agents [O(6)AA]). The defense is highly important, since O(6)AA are common environmental carcinogens, are formed endogenously during normal cellular metabolism and possibly inflammation, and are being used in cancer therapy. O(6)AA induced DNA damage is subject to repair, which is executed by MGMT, AlkB homologous proteins (ABH) and base excision repair (BER). Although this review focuses on MGMT, the mechanism of repair by ABH and BER will also be discussed. Experimental systems, in which MGMT has been modulated, revealed that O(6)-methylguanine (O(6)MeG) and O(6)-chloroethylguanine are major mutagenic, carcinogenic, recombinogenic, clastogenic and killing lesions. O(6)MeG-induced clastogenicity and cell death require MutS alpha-dependent mismatch repair (MMR), whereas O(6)-chloroethylguanine-induced killing occurs independently of MMR. Extensive DNA replication is required for O(6)MeG to provoke cytotoxicity. In MGMT depleted cells, O(6)MeG induces apoptosis almost exclusively, barely any necrosis, which is presumably due to the remarkable ability of secondarily formed DNA double-strand breaks (DSBs) to trigger apoptosis via ATM/ATR, Chk1, Chk2, p53 and p73. Depending on the cellular background, O(6)MeG activates both the death receptor and the mitochondrial apoptotic pathway. The inter-individual expression of MGMT in human lymphocytes is highly variable. Given the key role of MGMT in cellular defense, determination of MGMT activity could be useful for assessing a patient's drug sensitivity. MGMT is expressed at highly variable amounts in human tumors. In gliomas, a correlation was found between MGMT activity, MGMT promoter methylation and response to O(6)AA. Although the human MGMT gene is inducible by glucocorticoids and genotoxins such as radiation and alkylating agents, the role of this induction in the protection against carcinogens and the development of chemotherapeutic alkylating drug resistance are still unclear. Modulation of MGMT expression in tumors and normal tissue is currently being investigated as a possible strategy for improving cancer therapy.
Collapse
Affiliation(s)
- Bernd Kaina
- Department of Toxicology, University of Mainz, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany.
| | | | | | | |
Collapse
|
28
|
Wyatt MD, Pittman DL. Methylating agents and DNA repair responses: Methylated bases and sources of strand breaks. Chem Res Toxicol 2007; 19:1580-94. [PMID: 17173371 PMCID: PMC2542901 DOI: 10.1021/tx060164e] [Citation(s) in RCA: 314] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The chemical methylating agents methylmethane sulfonate (MMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) have been used for decades as classical DNA damaging agents. These agents have been utilized to uncover and explore pathways of DNA repair, DNA damage response, and mutagenesis. MMS and MNNG modify DNA by adding methyl groups to a number of nucleophilic sites on the DNA bases, although MNNG produces a greater percentage of O-methyl adducts. There has been substantial progress elucidating direct reversal proteins that remove methyl groups and base excision repair (BER), which removes and replaces methylated bases. Direct reversal proteins and BER, thus, counteract the toxic, mutagenic, and clastogenic effects of methylating agents. Despite recent progress, the complexity of DNA damage responses to methylating agents is still being discovered. In particular, there is growing understanding of pathways such as homologous recombination, lesion bypass, and mismatch repair that react when the response of direct reversal proteins and BER is insufficient. Furthermore, the importance of proper balance within the steps in BER has been uncovered with the knowledge that DNA structural intermediates during BER are deleterious. A number of issues complicate the elucidation of the downstream responses when direct reversal is insufficient or BER is imbalanced. These include inter-species differences, cell-type-specific differences within mammals and between cancer cell lines, and the type of methyl damage or BER intermediate encountered. MMS also carries a misleading reputation of being a radiomimetic, that is, capable of directly producing strand breaks. This review focuses on the DNA methyl damage caused by MMS and MNNG for each site of potential methylation to summarize what is known about the repair of such damage and the downstream responses and consequences if the damage is not repaired.
Collapse
Affiliation(s)
- Michael D Wyatt
- Department of Basic Pharmaceutical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina 29208, USA.
| | | |
Collapse
|
29
|
van den Broek WJAA, Nelen MR, van der Heijden GW, Wansink DG, Wieringa B. Fen1does not control somatic hypermutability of the (CTG)n· (CAG)nrepeat in a knock-in mouse model for DM1. FEBS Lett 2006; 580:5208-14. [PMID: 16978612 DOI: 10.1016/j.febslet.2006.08.059] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Revised: 08/15/2006] [Accepted: 08/20/2006] [Indexed: 11/16/2022]
Abstract
The mechanism of trinucleotide repeat expansion, an important cause of neuromuscular and neurodegenerative diseases, is poorly understood. We report here on the study of the role of flap endonuclease 1 (Fen1), a structure-specific nuclease with both 5' flap endonuclease and 5'-3' exonuclease activity, in the somatic hypermutability of the (CTG)(n)*(CAG)(n) repeat of the DMPK gene in a mouse model for myotonic dystrophy type 1 (DM1). By intercrossing mice with Fen1 deficiency with transgenics with a DM1 (CTG)(n)*(CAG)(n) repeat (where 104n110), we demonstrate that Fen1 is not essential for faithful maintenance of this repeat in early embryonic cleavage divisions until the blastocyst stage. Additionally, we found that the frequency of somatic DM1 (CTG)(n)*(CAG)(n) repeat instability was essentially unaltered in mice with Fen1 haploinsufficiency up to 1.5 years of age. Based on these findings, we propose that Fen1, despite its role in DNA repair and replication, is not primarily involved in maintaining stability at the DM1 locus.
Collapse
Affiliation(s)
- Walther J A A van den Broek
- Department of Cell Biology, Radboud University Nijmegen Medical Centre, Nijmegen Centre for Molecular Life Sciences, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | | | | | | | | |
Collapse
|
30
|
Rossi ML, Purohit V, Brandt PD, Bambara RA. Lagging strand replication proteins in genome stability and DNA repair. Chem Rev 2006; 106:453-73. [PMID: 16464014 DOI: 10.1021/cr040497l] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Marie L Rossi
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, New York 14642, USA
| | | | | | | |
Collapse
|
31
|
Nojima K, Hochegger H, Saberi A, Fukushima T, Kikuchi K, Yoshimura M, Orelli BJ, Bishop DK, Hirano S, Ohzeki M, Ishiai M, Yamamoto K, Takata M, Arakawa H, Buerstedde JM, Yamazoe M, Kawamoto T, Araki K, Takahashi JA, Hashimoto N, Takeda S, Sonoda E. Multiple repair pathways mediate tolerance to chemotherapeutic cross-linking agents in vertebrate cells. Cancer Res 2006; 65:11704-11. [PMID: 16357182 DOI: 10.1158/0008-5472.can-05-1214] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Cross-linking agents that induce DNA interstrand cross-links (ICL) are widely used in anticancer chemotherapy. Yeast genetic studies show that nucleotide excision repair (NER), Rad6/Rad18-dependent postreplication repair, homologous recombination, and cell cycle checkpoint pathway are involved in ICL repair. To study the contribution of DNA damage response pathways in tolerance to cross-linking agents in vertebrates, we made a panel of gene-disrupted clones from chicken DT40 cells, each defective in a particular DNA repair or checkpoint pathway, and measured the sensitivities to cross-linking agents, including cis-diamminedichloroplatinum (II) (cisplatin), mitomycin C, and melphalan. We found that cells harboring defects in translesion DNA synthesis (TLS), Fanconi anemia complementation groups (FANC), or homologous recombination displayed marked hypersensitivity to all the cross-linking agents, whereas NER seemed to play only a minor role. This effect of replication-dependent repair pathways is distinctively different from the situation in yeast, where NER seems to play a major role in dealing with ICL. Cells deficient in Rev3, the catalytic subunit of TLS polymerase Polzeta, showed the highest sensitivity to cisplatin followed by fanc-c. Furthermore, epistasis analysis revealed that these two mutants work in the same pathway. Our genetic comprehensive study reveals a critical role for DNA repair pathways that release DNA replication block at ICLs in cellular tolerance to cross-linking agents and could be directly exploited in designing an effective chemotherapy.
Collapse
|
32
|
Wu X, Takenaka K, Sonoda E, Hochegger H, Kawanishi S, Kawamoto T, Takeda S, Yamazoe M. Critical roles for polymerase zeta in cellular tolerance to nitric oxide-induced DNA damage. Cancer Res 2006; 66:748-54. [PMID: 16424005 DOI: 10.1158/0008-5472.can-05-2884] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Nitric oxide (NO), a signal transmitter involved in inflammation and regulation of smooth muscle and neurons, seems to cause mutagenesis, but its mechanisms have remained elusive. To gain an insight into NO-induced genotoxicity, we analyzed the effect of NO on a panel of chicken DT40 clones deficient in DNA repair pathways, including base and nucleotide excision repair, double-strand break repair, and translesion DNA synthesis (TLS). Our results show that cells deficient in Rev1 and Rev3, a subunit essential for DNA polymerase zeta (Polzeta), are hypersensitive to killing by two chemical NO donors, spermine NONOate and S-nitroso-N-acetyl-penicillamine. Mitotic chromosomal analysis indicates that the hypersensitivity is caused by a significant increase in the level of induced chromosomal breaks. The data reveal the critical role of TLS polymerases in cellular tolerance to NO-induced DNA damage and suggest the contribution of these error-prone polymerases to accumulation of single base substitutions.
Collapse
Affiliation(s)
- Xiaohua Wu
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | | | | | | | | | | | | | | |
Collapse
|
33
|
Kikuchi K, Taniguchi Y, Hatanaka A, Sonoda E, Hochegger H, Adachi N, Matsuzaki Y, Koyama H, van Gent DC, Jasin M, Takeda S. Fen-1 facilitates homologous recombination by removing divergent sequences at DNA break ends. Mol Cell Biol 2005; 25:6948-55. [PMID: 16055708 PMCID: PMC1190240 DOI: 10.1128/mcb.25.16.6948-6955.2005] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Homologous recombination (HR) requires nuclease activities at multiple steps, but the contribution of individual nucleases to the processing of double-strand DNA ends at different stages of HR has not been clearly defined. We used chicken DT40 cells to investigate the role of flap endonuclease 1 (Fen-1) in HR. FEN-1-deficient cells exhibited a significant decrease in the efficiency of immunoglobulin gene conversion while being proficient in recombination between sister chromatids, suggesting that Fen-1 may play a role in HR between sequences of considerable divergence. To clarify whether sequence divergence at DNA ends is truly the reason for the observed HR defect in FEN-1(-/-) cells we inserted a unique I-SceI restriction site in the genome and tested various donor and recipient HR substrates. We found that the efficiency of HR-mediated DNA repair was indeed greatly diminished when divergent sequences were present at the DNA break site. We conclude that Fen-1 eliminates heterologous sequences at DNA damage site and facilitates DNA repair by HR.
Collapse
Affiliation(s)
- Koji Kikuchi
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo-ku, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Shen B, Singh P, Liu R, Qiu J, Zheng L, Finger LD, Alas S. Multiple but dissectible functions of FEN-1 nucleases in nucleic acid processing, genome stability and diseases. Bioessays 2005; 27:717-29. [PMID: 15954100 DOI: 10.1002/bies.20255] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Flap EndoNuclease-1 (FEN-1) is a multifunctional and structure-specific nuclease involved in nucleic acid processing pathways. It plays a critical role in maintaining human genome stability through RNA primer removal, long-patch base excision repair and resolution of dinucleotide and trinucleotide repeat secondary structures. In addition to its flap endonuclease (FEN) and nick exonuclease (EXO) activities, a new gap endonuclease (GEN) activity has been characterized. This activity may be important in apoptotic DNA fragmentation and in resolving stalled DNA replication forks. The multiple functions of FEN-1 are regulated via several means, including formation of complexes with different protein partners, nuclear localization in response to cell cycle or DNA damage and post-translational modifications. Its functional deficiency is predicted to cause genetic diseases, including Huntington's disease, myotonic dystrophy and cancers. This review summarizes the knowledge gained through efforts in the past decade to define its structural elements for specific activities and possible pathological consequences of altered functions of this multirole player.
Collapse
Affiliation(s)
- Binghui Shen
- Department of Radiation Biology, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA 91010, USA.
| | | | | | | | | | | | | |
Collapse
|
35
|
Shi BS, Cai ZN, Yang J, Yu YN. N-methyl-N'-nitro-N-nitrosoguanidine sensitivity, mutator phenotype and sequence specificity of spontaneous mutagenesis in FEN-1-deficient cells. Mutat Res 2005; 556:1-9. [PMID: 15491627 DOI: 10.1016/j.mrfmmm.2004.05.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2003] [Revised: 05/18/2004] [Accepted: 05/28/2004] [Indexed: 11/26/2022]
Abstract
Intact pZ189 DNA was allowed to replicate in FL-FEN-1(-) cell line that was established in this laboratory in which the expression of FEN-1 gene was blocked by dexamethasone-inducible expression of antisense RNA to FEN-1. E. coli MBM7070 was transfected with the replicated plasmid, and those with mutations in the supF gene were identified. The frequency of mutants that did not contain recognizable changes in the electrophoretic mobility of the plasmid DNA was scored. The frequency of such mutants was 19.1 x 10(-4) (34/17781), significantly higher than those of 2.9 x 10(-4) (4/13668) and 3.0 x 10(-4) (3/9857) in the corresponding controls, respectively. Sequence analysis of the supF genes of these mutants showed that all (37/37) the base substitutions occurred at C:G base pairs; 68% (23/37) of the base substitutions were base transversions, while 32% (12/37) were transitions. Approximately 76% (23/37) of these base substitutions occurred frequently at nine positions; two of these sites contain triple pyrimidine (T or C) repeat upstream to the mutated base; four of these sites consist of 5'-TTN1N2 and mutations occurred at N1 site sequence; another two sites have the characteristics of triple A flanked at both 5' and 3' side by TCT, with the base substitution occurring at C in the context sequence. These data suggested that these sites are the hot spot of mutagenesis in plasmid replicated in FEN-1-deficient cells. Besides the mutator phenotype of the FEN-1-deficient cell, it was also demonstrated that FEN-1-deficient cell exhibited an increased N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) sensitive phenotype.
Collapse
Affiliation(s)
- Bin-Shan Shi
- Department of Pathophysiology, Center of Environmental Genomics, Zhejiang University School of Medicine, 353 Yan'an Road, Hangzhou 310031, China
| | | | | | | |
Collapse
|
36
|
Wang W, Bambara RA. Human Bloom protein stimulates flap endonuclease 1 activity by resolving DNA secondary structure. J Biol Chem 2004; 280:5391-9. [PMID: 15579905 DOI: 10.1074/jbc.m412359200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Flap endonuclease 1 (FEN1) participates in removal of RNA primers of Okazaki fragments, several DNA repair pathways, and genome stability maintenance. Defects in yeast FEN1 produce chromosomal instability, hyper-recombination, and sequence duplication. These occur because flaps produced during replication are not promptly removed. Long-lived flaps sustain breaks and form misaligned bubble structures that produce duplications. Flaps that can form secondary structure inhibit even wild-type FEN1 and are more likely to form bubbles. Although proliferating cell nuclear antigen stimulates FEN1, it cannot resolve secondary structures. Bloom protein (BLM) is a 3'-5' helicase, mutated in Bloom syndrome. BLM has been reported to interact with and stimulate FEN1 independent of helicase function. We found activation of the helicase by ATP did not alter BLM stimulation of cleavage of unstructured flaps. However, BLM stimulation of FEN1 cleavage of foldback flaps, bubbles, or triplet repeats was increased by an additional increment when ATP was added. Helicase-dependent stimulation of FEN1 cleavage was robust over a range of sizes of the single-stranded part of bubbles. However, increasing the length of the 5' annealed region of the bubble ultimately counteracted the stimulatory capacity of the BLM helicase. Moderate helicase-dependent stimulation was observed with both fixed and equilibrating CTG flaps. Our results suggest that BLM suppresses genome instability by aiding FEN1 cleavage of structure-containing flaps.
Collapse
Affiliation(s)
- Wensheng Wang
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave., Rochester, NY 14642, USA
| | | |
Collapse
|
37
|
Abstract
One strand of cellular DNA is generated as RNA-initiated discontinuous segments called Okazaki fragments that later are joined. The RNA terminated region is displaced into a 5' single-stranded flap, which is removed by the structure-specific flap endonuclease 1 (FEN1), leaving a nick for ligation. Similarly, in long-patch base excision repair, a damaged nucleotide is displaced into a flap and removed by FEN1. FEN1 is a genome stabilization factor that prevents flaps from equilibrating into structures that lead to duplications and deletions. As an endonuclease, FEN1 enters the flap from the 5' end and then tracks to cleave the flap base. Cleavage is oriented by the formation of a double flap. Analyses of FEN1 crystal structures suggest mechanisms for tracking and cleavage. Some flaps can form self-annealed and template bubble structures that interfere with FEN1. FEN1 interacts with other nucleases and helicases that allow it to act efficiently on structured flaps. Genetic and biochemical analyses continue to reveal many roles of FEN1.
Collapse
Affiliation(s)
- Yuan Liu
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
| | | | | |
Collapse
|
38
|
Yamazoe M, Sonoda E, Hochegger H, Takeda S. Reverse genetic studies of the DNA damage response in the chicken B lymphocyte line DT40. DNA Repair (Amst) 2004; 3:1175-85. [PMID: 15279806 DOI: 10.1016/j.dnarep.2004.03.039] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In the 'post-genome' era, reverse genetics is one of the most informative and powerful means to investigate protein function. The chicken B lymphocyte line DT40 is widely used for reverse genetics because the cells have a number of advantages, including efficient gene targeting as well as a remarkably stable phenotype. Furthermore, the absence of functional p53 in DT40 cells enables identification of DNA damage using chromosome analysis by suppressing damage-induced apoptosis during interphase. This review summarizes the contribution of DT40 cells to reverse genetic studies of DNA damage response pathways in higher eukaryotic cells.
Collapse
Affiliation(s)
- Mitsuyoshi Yamazoe
- CRESTO, The Japan Science and Technology Corporation, Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | | | | | | |
Collapse
|
39
|
Yamaguchi T, Namekawa SH, Hamada FN, Kasai N, Nara T, Watanabe K, Iwabata K, Ishizaki T, Ishii S, Koshiyama A, Inagaki S, Kimura S, Sakaguchi K. Expression of flap endonuclease-1 during meiosis in a basidiomycete, Coprinus cinereus. Fungal Genet Biol 2004; 41:493-500. [PMID: 15050538 DOI: 10.1016/j.fgb.2004.01.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2003] [Accepted: 01/16/2004] [Indexed: 11/25/2022]
Abstract
In the basidiomycete Coprinus cinereus (C. cinereus), which shows a highly synchronous meiotic cell cycle, the meiotic prophase I cells demonstrate flap endonuclease-1 activity. To investigate its role during meiosis, we isolated a C. cinereus cDNA homolog of flap endonuclease-1 (CcFEN-1), 1377bp in length with the open reading frame (ORF) encoding a predicted molecular mass of 51 kDa. At amino-acid residues Glu276-Pro345, a specific inserted sequence composed of 70 amino acids rich in polar forms was found to exist, without sequence identity to other eukaryotic FEN-1 or the polar amino acid rich sequences found in C. cinereus PCNA and C. cinereus DNA ligase IV, although the lengths and percentages of polar amino acids were similar. Northern hybridization analysis indicated CcFEN-1 to be expressed not only in the pre-meiotic S phase but also in meiotic prophase I. The roles of CcFEN-1 during meiosis are discussed.
Collapse
MESH Headings
- Amino Acid Sequence
- Amino Acids/chemistry
- Amino Acids/genetics
- Coprinus/enzymology
- Coprinus/genetics
- DNA Ligase ATP
- DNA Ligases/genetics
- DNA, Complementary/chemistry
- DNA, Complementary/isolation & purification
- DNA, Fungal/chemistry
- DNA, Fungal/isolation & purification
- Flap Endonucleases/genetics
- Flap Endonucleases/metabolism
- Gene Expression Regulation, Fungal
- Meiosis/physiology
- Models, Molecular
- Molecular Sequence Data
- Molecular Weight
- Open Reading Frames
- Phylogeny
- Proliferating Cell Nuclear Antigen/genetics
- Prophase/genetics
- Prophase/physiology
- RNA, Fungal/analysis
- RNA, Messenger/analysis
- S Phase/genetics
- S Phase/physiology
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
Collapse
Affiliation(s)
- Taiki Yamaguchi
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba-ken 278-8510, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Islaih M, Li B, Kadura IA, Reid-Hubbard JL, Deahl JT, Altizer JL, Watson DE, Newton RK. Comparison of gene expression changes induced in mouse and human cells treated with direct-acting mutagens. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2004; 44:401-419. [PMID: 15515172 DOI: 10.1002/em.20065] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Exposure to DNA-damaging agents can elicit a variety of stress-related responses that may alter the gene expression of numerous biological pathways. We used Affymetrix microarrays to detect gene expression changes in mouse lymphoma (L5178Y) and human lymphoblastoid (TK6) cells in response to methyl methanesulfonate (MMS; a prototypical alkylating agent) and bleomycin (a prototypical oxidative mutagen). Cells were treated for 4 hr, and RNA was isolated either at the end of the treatment or after a 20-hr recovery period. Two concentrations of each agent were used based on cytotoxicity levels and Tk mutant frequencies. Our microarray data analysis indicated that MMS and bleomycin gene expression responses were considerably different in mouse cells versus human cells. The results also suggested that more comprehensive cellular responses to MMS and bleomycin occurred in TK6 cells than in L5178Y cells. In contrast to L5178Y cells, the response of TK6 cells to MMS and bleomycin was characterized by the induction of p53-dependent genes that are involved in DNA repair, cell cycle regulation, and apoptosis. It appears that the induction of DNA damage by MMS in human TK6 cells mediated cytotoxicity and led to decreased cell survival. This may explain the greater sensitivity of TK6 cells to cytotoxic effects of MMS compared to L5178Y cells. Bleomycin exerted comparable cytotoxic effects in the two cell lines. Overall, these studies were unable to identify distinctive gene expression changes that differentiated bleomycin from MMS in either TK6 cells or mouse lymphoma cells.
Collapse
Affiliation(s)
- Mohammed Islaih
- Eli Lilly and Company, Lilly Research Laboratories, Greenfield, Indiana 46140, USA.
| | | | | | | | | | | | | | | |
Collapse
|
41
|
Kimura S, Furukawa T, Kasai N, Mori Y, Kitamoto HK, Sugawara F, Hashimoto J, Sakaguchi K. Functional characterization of two flap endonuclease-1 homologues in rice. Gene 2003; 314:63-71. [PMID: 14527718 DOI: 10.1016/s0378-1119(03)00694-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Flap endonuclease-1 (FEN-1) is an important enzyme involved in DNA replication and repair. Previously, we isolated and characterized a complementary DNA (cDNA) from rice (Oryza sativa) encoding a protein which shows homology with the eukaryotic flap endonuclease-1 (FEN-1). In this report, we found that rice (O. sativa L. cv. Nipponbare) possessed two FEN-1 homologues designated as OsFEN-1a and OsFEN-1b. The OsFEN-1a and OsFEN-1b genes were mapped to chromosome 5 and 3, respectively. Both genes contained 17 exons and 16 introns. Alignment of OsFEN-1a protein with OsFEN-1b protein showed a high degree of sequence similarity, particularly around the N and I domains. Northern hybridization and in situ hybridization analysis demonstrated preferential expression of OsFEN-1a and OsFEN-1b in proliferating tissues such as the shoot apical meristem or young leaves. The levels of OsFEN-1a and OsFEN-1b expression were significantly reduced when cell proliferation was temporarily halted by the removal of sucrose from the growth medium. When the growth-halted cells began to regrow following the addition of sucrose to the medium, both OsFEN-1a and OsFEN-1b were again expressed at high level. These results suggested that OsFEN-1a and OsFEN-1b are required for cell proliferation. Functional complementation assay suggested that OsFEN-1a cDNA had the ability to complement Saccharomyces cerevisiae rad27 null mutant. On the other hand, OsFEN-1b cDNA could not complement the rad27 mutant. The roles of OsFEN-1a and OsFEN-1b in plant DNA replication and repair are discussed.
Collapse
Affiliation(s)
- Seisuke Kimura
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Chiba, 278-8510, Noda, Japan
| | | | | | | | | | | | | | | |
Collapse
|
42
|
Adachi N, Suzuki H, Iiizumi S, Koyama H. Hypersensitivity of nonhomologous DNA end-joining mutants to VP-16 and ICRF-193: implications for the repair of topoisomerase II-mediated DNA damage. J Biol Chem 2003; 278:35897-902. [PMID: 12842886 DOI: 10.1074/jbc.m306500200] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A number of clinically useful anticancer drugs, including etoposide (VP-16), target DNA topoisomerase (topo) II. These drugs, referred to as topo II poisons, stabilize cleavable complexes, thereby generating DNA double-strand breaks. Bis-2,6-dioxopiperazines such as ICRF-193 also inhibit topo II by inducing a distinct type of DNA damage, termed topo II clamps, which has been believed to be devoid of double-strand breaks. Despite the biological and clinical importance, the molecular mechanisms for the repair of topo II-mediated DNA damage remain largely unknown. Here, we perform genetic analyses using the chicken DT40 cell line to investigate how DNA lesions caused by topo II inhibitors are repaired. Notably, we show that LIG4-/- and KU70-/- cells, which are defective in nonhomologous DNA end-joining (NHEJ), are extremely sensitive to both VP-16 and ICRF-193. In contrast, RAD54-/- cells (defective in homologous recombination) are much less hypersensitive to VP-16 than the NHEJ mutants and, more importantly, are not hypersensitive to ICRF-193. Our results provide the first evidence that NHEJ is the predominant pathway for the repair of topo II-mediated DNA damage; that is, cleavable complexes and topo II clamps. The outstandingly increased cytotoxicity of topo II inhibitors in the absence of NHEJ suggests that simultaneous inhibition of topo II and NHEJ would provide a powerful protocol in cancer chemotherapy involving topo II inhibitors.
Collapse
Affiliation(s)
- Noritaka Adachi
- Kihara Institute for Biological Research, Graduate School of Integrated Science, Yokohama City University, Totsuka-ku, Yokohama 244-0813, Japan.
| | | | | | | |
Collapse
|
43
|
Larsen E, Gran C, Saether BE, Seeberg E, Klungland A. Proliferation failure and gamma radiation sensitivity of Fen1 null mutant mice at the blastocyst stage. Mol Cell Biol 2003; 23:5346-53. [PMID: 12861020 PMCID: PMC165721 DOI: 10.1128/mcb.23.15.5346-5353.2003] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Flap endonuclease 1 (FEN1) has been shown to remove 5' overhanging flap intermediates during base excision repair and to process the 5' ends of Okazaki fragments during lagging-strand DNA replication in vitro. To assess the in vivo role of the mammalian enzyme in repair and replication, we used a gene-targeting approach to generate mice lacking a functional Fen1 gene. Heterozygote animals appear normal, whereas complete depletion of FEN1 causes early embryonic lethality. Fen1(-/-) blastocysts fail to form inner cell mass during cellular outgrowth, and a complete inactivation of DNA synthesis in giant cells of blastocyst outgrowth was observed. Exposure of Fen1(-/-) blastocysts to gamma radiation caused extensive apoptosis, implying an essential role for FEN1 in the repair of radiation-induced DNA damage in vivo. Our data thus provide in vivo evidence for an essential function of FEN1 in DNA repair, as well as in DNA replication.
Collapse
Affiliation(s)
- Elisabeth Larsen
- Centre for Molecular Biology and Neuroscience, Institute of Medical Microbiology, The National Hospital, University of Oslo, 0027 Oslo, Norway
| | | | | | | | | |
Collapse
|
44
|
Henneke G, Koundrioukoff S, Hübscher U. Phosphorylation of human Fen1 by cyclin-dependent kinase modulates its role in replication fork regulation. Oncogene 2003; 22:4301-13. [PMID: 12853968 DOI: 10.1038/sj.onc.1206606] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cyclin-dependent kinase (Cdk) Cdk1-Cyclin A can phosphorylate Flap endonuclease 1 (Fen1), a key-enzyme of the DNA replication machinery, in late S phase. Cdk1-cyclin A forms a complex in vitro and in vivo with Fen1. Furthermore, Fen1 phosphorylation is detected in vivo and depends upon Cdks activity. As a functional consequence of phosphorylation by Cdk1-Cyclin A in vitro, endo- and exonuclease activities of Fen1 are reduced whereas its DNA binding is not affected. Moreover, phosphorylation of Fen1 by Cdk1-Cyclin A abrogates its proliferating cell nuclear antigen (PCNA) binding thus preventing stimulation of Fen1 by PCNA. Concomitantly, human cells expressing the S187A mutant defective for Cdk1-Cyclin A phosphorylation accumulate in S phase consistent with a failure in cell cycle regulation through DNA replication. Our results suggest a novel regulatory role of Cdks onto the end of S phase by targeting directly a key enzyme involved in DNA replication.
Collapse
Affiliation(s)
- Ghislaine Henneke
- Institute of Veterinary Biochemistry and Molecular Biology, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | | | | |
Collapse
|
45
|
Henneke G, Friedrich-Heineken E, Hübscher U. Flap endonuclease 1: a novel tumour suppresser protein. Trends Biochem Sci 2003; 28:384-90. [PMID: 12878006 DOI: 10.1016/s0968-0004(03)00138-5] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Ghislaine Henneke
- Institute of Veterinary Biochemistry and Molecular Biology, University of Zürich-Irchel, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | | | | |
Collapse
|
46
|
Friedrich-Heineken E, Henneke G, Ferrari E, Hübscher U. The acetylatable lysines of human Fen1 are important for endo- and exonuclease activities. J Mol Biol 2003; 328:73-84. [PMID: 12683998 DOI: 10.1016/s0022-2836(03)00270-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Human Fen1 can be acetylated in vivo and in vitro resulting in reduced endonuclease and exonuclease activities in vitro. Acetylation occurs at four lysines located at the C terminus of Fen1, which is important for DNA binding. In this paper we show that Fen1 mutant proteins lacking the lysines at the C terminus have both reduced PCNA independent exonucleolytic and endonucleolytic activities. However, lysines at the C terminus are not required for PCNA stimulation of human Fen1. A double flap substrate was optimal for human Fen1 endonuclease and did not require the C-terminal lysines. Similarly, a one nucleotide 3'-overhang nick substrate was optimal for human Fen1 exonuclease and also did not require the C-terminal lysines. Finally, we found by an electromobility shift assay that human Fen1 had a different mode of binding with a double flap substrate containing a one nucleotide 3'-tail when compared to various other flap substrates. Taken together, our results confirm the double flap substrate as the likely in vivo intermediate for human Fen1 and that the C-terminal lysines are important for the endonuclease and exonuclease activities likely through DNA binding.
Collapse
Affiliation(s)
- Erica Friedrich-Heineken
- Institute of Veterinary Biochemistry and Molecular Biology, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | | | | | | |
Collapse
|
47
|
Brown WRA, Hubbard SJ, Tickle C, Wilson SA. The chicken as a model for large-scale analysis of vertebrate gene function. Nat Rev Genet 2003; 4:87-98. [PMID: 12560806 DOI: 10.1038/nrg998] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- William R A Brown
- Institute of Genetics, Nottingham University, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | | | | | | |
Collapse
|