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Liu K, Yuan X, Yang T, Deng D, Chen Y, Tang M, Zhang C, Zou Y, Zhang S, Li D, Shi M, Guo Y, Zhou Y, Zhao M, Yang Z, Chen L. Discovery, Optimization, and Evaluation of Potent and Selective DNA-PK Inhibitors in Combination with Chemotherapy or Radiotherapy for the Treatment of Malignancies. J Med Chem 2024; 67:245-271. [PMID: 38117951 DOI: 10.1021/acs.jmedchem.3c01338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
Given the multifaceted biological functions of DNA-PK encompassing DNA repair pathways and beyond, coupled with the susceptibility of DNA-PK-deficient cells to DNA-damaging agents, significant strides have been made in the pursuit of clinical potential for DNA-PK inhibitors as synergistic adjuncts to chemo- or radiotherapy. Nevertheless, although substantial progress has been made with the discovery of potent inhibitors of DNA-PK, the clinical trial landscape requires even more potent and selective molecules. This necessitates further endeavors to expand the repertoire of clinically accessible DNA-PK inhibitors for the ultimate benefit of patients. Described herein are the obstacles that were encountered and the solutions that were found, which eventually led to the identification of compound 31t. This compound exhibited a remarkable combination of robust potency and exceptional selectivity along with favorable in vivo profiles as substantiated by pharmacokinetic studies in rats and pharmacodynamic assessments in H460, BT474, and A549 xenograft models.
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Affiliation(s)
- Kongjun Liu
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Xue Yuan
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Tao Yang
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Dexin Deng
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Yong Chen
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Minghai Tang
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Chufeng Zhang
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Yurong Zou
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Shunjie Zhang
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Dan Li
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Mingsong Shi
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Yong Guo
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Yanting Zhou
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Min Zhao
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Zhuang Yang
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Lijuan Chen
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
- Chengdu Zenitar Biomedical Technology Co., Ltd., Chengdu 610041, China
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So A, Dardillac E, Muhammad A, Chailleux C, Sesma-Sanz L, Ragu S, Le Cam E, Canitrot Y, Masson J, Dupaigne P, Lopez BS, Guirouilh-Barbat J. OUP accepted manuscript. Nucleic Acids Res 2022; 50:2651-2666. [PMID: 35137208 PMCID: PMC8934640 DOI: 10.1093/nar/gkac073] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 01/18/2022] [Accepted: 01/25/2022] [Indexed: 11/23/2022] Open
Abstract
Selection of the appropriate DNA double-strand break (DSB) repair pathway is decisive for genetic stability. It is proposed to act according to two steps: 1-canonical nonhomologous end-joining (C-NHEJ) versus resection that generates single-stranded DNA (ssDNA) stretches; 2-on ssDNA, gene conversion (GC) versus nonconservative single-strand annealing (SSA) or alternative end-joining (A-EJ). Here, we addressed the mechanisms by which RAD51 regulates this second step, preventing nonconservative repair in human cells. Silencing RAD51 or BRCA2 stimulated both SSA and A-EJ, but not C-NHEJ, validating the two-step model. Three different RAD51 dominant-negative forms (DN-RAD51s) repressed GC and stimulated SSA/A-EJ. However, a fourth DN-RAD51 repressed SSA/A-EJ, although it efficiently represses GC. In living cells, the three DN-RAD51s that stimulate SSA/A-EJ failed to load efficiently onto damaged chromatin and inhibited the binding of endogenous RAD51, while the fourth DN-RAD51, which inhibits SSA/A-EJ, efficiently loads on damaged chromatin. Therefore, the binding of RAD51 to DNA, rather than its ability to promote GC, is required for SSA/A-EJ inhibition by RAD51. We showed that RAD51 did not limit resection of endonuclease-induced DSBs, but prevented spontaneous and RAD52-induced annealing of complementary ssDNA in vitro. Therefore, RAD51 controls the selection of the DSB repair pathway, protecting genome integrity from nonconservative DSB repair through ssDNA occupancy, independently of the promotion of CG.
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Affiliation(s)
- Ayeong So
- Université de Paris, INSERM U1016, UMR 8104 CNRS, Institut Cochin, Equipe Labellisée Ligue Contre le Cancer, France
- CNRS UMR 8200, Gustave-Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, 94805 Villejuif, France
| | - Elodie Dardillac
- Université de Paris, INSERM U1016, UMR 8104 CNRS, Institut Cochin, Equipe Labellisée Ligue Contre le Cancer, France
- CNRS UMR 8200, Gustave-Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, 94805 Villejuif, France
| | - Ali Muhammad
- Genome Maintenance and Molecular Microscopy UMR 9019 CNRS, Université Paris-Saclay, Gustave Roussy, F-94805, Villejuif Cedex, France
| | | | - Laura Sesma-Sanz
- Genome Stability Laboratory, CHU de Québec Research Center (Oncology Division), Quebec City, QC, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Quebec City, QC, Canada
| | - Sandrine Ragu
- Université de Paris, INSERM U1016, UMR 8104 CNRS, Institut Cochin, Equipe Labellisée Ligue Contre le Cancer, France
- CNRS UMR 8200, Gustave-Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, 94805 Villejuif, France
| | - Eric Le Cam
- Genome Maintenance and Molecular Microscopy UMR 9019 CNRS, Université Paris-Saclay, Gustave Roussy, F-94805, Villejuif Cedex, France
| | - Yvan Canitrot
- CBI, CNRS UMR5088, LBCMCP, Toulouse University, Toulouse, France
| | - Jean Yves Masson
- Genome Stability Laboratory, CHU de Québec Research Center (Oncology Division), Quebec City, QC, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Quebec City, QC, Canada
| | - Pauline Dupaigne
- Genome Maintenance and Molecular Microscopy UMR 9019 CNRS, Université Paris-Saclay, Gustave Roussy, F-94805, Villejuif Cedex, France
| | - Bernard S Lopez
- To whom correspondence should be addressed. Tel: +33 1 53 73 27 40;
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Mohiuddin IS, Kang MH. DNA-PK as an Emerging Therapeutic Target in Cancer. Front Oncol 2019; 9:635. [PMID: 31380275 PMCID: PMC6650781 DOI: 10.3389/fonc.2019.00635] [Citation(s) in RCA: 122] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 06/27/2019] [Indexed: 12/21/2022] Open
Abstract
The DNA-dependent protein kinase (DNA-PK) plays an instrumental role in the overall survival and proliferation of cells. As a member of the phosphatidylinositol 3-kinase-related kinase (PIKK) family, DNA-PK is best known as a mediator of the cellular response to DNA damage. In this context, DNA-PK has emerged as an intriguing therapeutic target in the treatment of a variety of cancers, especially when used in conjunction with genotoxic chemotherapy or ionizing radiation. Beyond the DNA damage response, DNA-PK activity is necessary for multiple cellular functions, including the regulation of transcription, progression of the cell cycle, and in the maintenance of telomeres. Here, we review what is currently known about DNA-PK regarding its structure and established roles in DNA repair. We also discuss its lesser-known functions, the pharmacotherapies inhibiting its function in DNA repair, and its potential as a therapeutic target in a broader context.
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Affiliation(s)
- Ismail S Mohiuddin
- Cancer Center, Department of Pediatrics, Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Min H Kang
- Cancer Center, Department of Pediatrics, Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
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Frick A, Khare V, Paul G, Lang M, Ferk F, Knasmüller S, Beer A, Oberhuber G, Gasche C. Overt Increase of Oxidative Stress and DNA Damage in Murine and Human Colitis and Colitis-Associated Neoplasia. Mol Cancer Res 2018; 16:634-642. [PMID: 29378905 DOI: 10.1158/1541-7786.mcr-17-0451] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 11/17/2017] [Accepted: 01/02/2018] [Indexed: 11/16/2022]
Abstract
Patients with inflammatory bowel disease (IBD) have a higher risk of developing colitis-associated-cancer (CAC); however, the underlying processes of disease progression are not completely understood. Here, the molecular processes of inflammation-driven colon carcinogenesis were investigated using IL10-deficient mice (IL10 KO). IL10 KO mice were euthanized after development of colitis and dysplasia. IHC was performed for markers of colitis-induced DNA damage (CIDD): oxidative DNA lesions (8-oxoG), double-strand breaks (DSB; γH2AX). and DSB repair. MSI, LOH (Trp53, Apc), and global methylation (CIMP) were assessed on microdissected tissue. Comet assay for DNA damage, immunofluorescence, and immunoblotting were performed on intestinal organoids from wild-type (WT) and IL10 KO mice. Sequential biopsies and surgical specimens from IBD and CAC patients were used for IHC analysis. Severity of inflammation correlated with number of dysplasia. 8-oxoG and γH2AX-positive cells were significantly increased in inflamed and dysplastic areas along with activation of DSB repair. The amount of positively stained cells strongly correlated with degree of inflammation (8-oxoG: R = 0.923; γH2AX: R = 0.858). Neither CIMP, MSI nor LOH was observed. Enhanced DSBs in IL10 KO organoids were confirmed by comet assay and increased expression of γH2AX. Human clinical specimens exhibited significantly higher γH2AX and 8-oxoG in IBD, dysplasia, and CAC compared with normal mucosa. These data indicate that inflammation-driven colon carcinogenesis in IL10 KO mice and IBD patients is associated with oxidative DNA damage and overt presence of DSB. Mol Cancer Res; 16(4); 634-42. ©2018 AACR.
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Affiliation(s)
- Adrian Frick
- Department of Internal Medicine III, Division of Gastroenterology and Hepatology, Medical University of Vienna, Vienna, Austria
| | - Vineeta Khare
- Department of Internal Medicine III, Division of Gastroenterology and Hepatology, Medical University of Vienna, Vienna, Austria
| | - Gregor Paul
- Department of Internal Medicine III, Division of Gastroenterology and Hepatology, Medical University of Vienna, Vienna, Austria
| | - Michaela Lang
- Department of Internal Medicine III, Division of Gastroenterology and Hepatology, Medical University of Vienna, Vienna, Austria
| | - Franziska Ferk
- Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, Vienna, Austria
| | - Siegfried Knasmüller
- Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, Vienna, Austria
| | - Andrea Beer
- Clinical Institute of Pathology, Medical University of Vienna, Vienna Austria
| | - Georg Oberhuber
- Pathologie Soleiman, A.ö. Landeskrankenhaus-Universitäts-Kliniken Innsbruck, Innsbruck, Austria
| | - Christoph Gasche
- Department of Internal Medicine III, Division of Gastroenterology and Hepatology, Medical University of Vienna, Vienna, Austria.
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5
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So A, Le Guen T, Lopez BS, Guirouilh-Barbat J. Genomic rearrangements induced by unscheduled DNA double strand breaks in somatic mammalian cells. FEBS J 2017; 284:2324-2344. [PMID: 28244221 DOI: 10.1111/febs.14053] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 02/02/2017] [Accepted: 02/24/2017] [Indexed: 12/13/2022]
Abstract
DNA double-strand breaks (DSBs) are highly toxic lesions that can lead to profound genome rearrangements and/or cell death. They routinely occur in genomes due to endogenous or exogenous stresses. Efficient repair systems, canonical non-homologous end-joining and homologous recombination exist in the cell and not only ensure the maintenance of genome integrity but also, via specific programmed DNA double-strand breaks, permit its diversity and plasticity. However, these repair systems need to be tightly controlled because they can also generate genomic rearrangements. Thus, when DSB repair is not properly regulated, genome integrity is no longer guaranteed. In this review, we will focus on non-programmed genome rearrangements generated by DSB repair, in somatic cells. We first discuss genome rearrangements induced by homologous recombination and end-joining. We then discuss recently described rearrangement mechanisms, driven by microhomologies, that do not involve the joining of DNA ends but rather initiate DNA synthesis (microhomology-mediated break-induced replication, fork stalling and template switching and microhomology-mediated template switching). Finally, we discuss chromothripsis, which is the shattering of a localized region of the genome followed by erratic rejoining.
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Affiliation(s)
- Ayeong So
- CNRS UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer, Villejuif, France
| | - Tangui Le Guen
- CNRS UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer, Villejuif, France
| | - Bernard S Lopez
- CNRS UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer, Villejuif, France
| | - Josée Guirouilh-Barbat
- CNRS UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer, Villejuif, France
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Gelot C, Guirouilh-Barbat J, Lopez BS. The cohesin complex prevents the end-joining of distant DNA double-strand ends in S phase: Consequences on genome stability maintenance. Nucleus 2016; 7:339-45. [PMID: 27326661 DOI: 10.1080/19491034.2016.1194159] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
DNA double-strand break (DSB) repair is essential for genome stability maintenance, but the joining of distant DNA double strand ends (DSEs) inevitably leads to genome rearrangements. Therefore, DSB repair should be tightly controlled to secure genome stability while allowing genetic variability. Tethering of the proximal ends of a 2-ended DSB limits their mobility, protecting thus against their joining with a distant DSE. However, replication stress generates DSBs with only one DSE, on which tethering is impossible. Consistently, we demonstrated that the joining of 2 DSBs only 3.2 kb apart is repressed in the S, but not the G1, phase, revealing an additional mechanism limiting DNA ends mobility in S phase. The cohesin complex, by maintaining the 2 sister chromatids linked, limits DSEs mobility and thus represses the joining of distant DSEs, while allowing that of adjacent DSEs. At the genome scale, the cohesin complex protects against deletions, inversions, translocations and chromosome fusion.
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Affiliation(s)
- Camille Gelot
- a CNRS UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer , Villejuif , France
| | - Josée Guirouilh-Barbat
- a CNRS UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer , Villejuif , France
| | - Bernard S Lopez
- a CNRS UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer , Villejuif , France
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Gelot C, Guirouilh-Barbat J, Le Guen T, Dardillac E, Chailleux C, Canitrot Y, Lopez BS. The Cohesin Complex Prevents the End Joining of Distant DNA Double-Strand Ends. Mol Cell 2016; 61:15-26. [PMID: 26687679 DOI: 10.1016/j.molcel.2015.11.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 09/25/2015] [Accepted: 11/02/2015] [Indexed: 02/07/2023]
Abstract
The end joining of distant DNA double-strand ends (DSEs) can produce potentially deleterious rearrangements. We show that depletion of cohesion complex proteins specifically stimulates the end joining (both C-NHEJ and A-EJ) of distant, but not close, I-SceI-induced DSEs in S/G2 phases. At the genome level, whole-exome sequencing showed that ablation of RAD21 or Sororin produces large chromosomal rearrangements (translocation, duplication, deletion). Moreover, cytogenetic analysis showed that RAD21 silencing leads to the formation of chromosome fusions synergistically with replication stress, which generates distant single-ended DSEs. These data reveal a role for the cohesin complex in protecting against genome rearrangements arising from the ligation of distant DSEs in S/G2 phases (both long-range DSEs and those that are only a few kilobases apart), while keeping end joining fully active for close DSEs. Therefore, this role likely involves limitation of DSE motility specifically in S phase, rather than inhibition of the end-joining machinery itself.
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Affiliation(s)
- Camille Gelot
- Centre National de la Recherche Scientifique (CNRS) UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer, 114 Rue Edouard Vaillant, 94805 Villejuif, France
| | - Josée Guirouilh-Barbat
- Centre National de la Recherche Scientifique (CNRS) UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer, 114 Rue Edouard Vaillant, 94805 Villejuif, France
| | - Tangui Le Guen
- Centre National de la Recherche Scientifique (CNRS) UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer, 114 Rue Edouard Vaillant, 94805 Villejuif, France
| | - Elodie Dardillac
- Centre National de la Recherche Scientifique (CNRS) UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer, 114 Rue Edouard Vaillant, 94805 Villejuif, France
| | - Catherine Chailleux
- Université de Toulouse UPS, CNRS UMR 5088, Laboratoire de Biologie Cellulaire et Moléculaire du Contrôle de la Prolifération (LBCMCP), 31062 Toulouse, France
| | - Yvan Canitrot
- Université de Toulouse UPS, CNRS UMR 5088, Laboratoire de Biologie Cellulaire et Moléculaire du Contrôle de la Prolifération (LBCMCP), 31062 Toulouse, France
| | - Bernard S Lopez
- Centre National de la Recherche Scientifique (CNRS) UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer, 114 Rue Edouard Vaillant, 94805 Villejuif, France.
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Taty-Taty GC, Chailleux C, Quaranta M, So A, Guirouilh-Barbat J, Lopez BS, Bertrand P, Trouche D, Canitrot Y. Control of alternative end joining by the chromatin remodeler p400 ATPase. Nucleic Acids Res 2015; 44:1657-68. [PMID: 26578561 PMCID: PMC4770216 DOI: 10.1093/nar/gkv1202] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 10/26/2015] [Indexed: 12/11/2022] Open
Abstract
Repair of DNA double-strand breaks occurs in a chromatin context that needs to be modified and remodeled to allow suitable access to the different DNA repair machineries. Of particular importance for the maintenance of genetic stability is the tight control of error-prone pathways, such as the alternative End Joining pathway. Here, we show that the chromatin remodeler p400 ATPase is a brake to the use of alternative End Joining. Using specific intracellular reporter susbstrates we observed that p400 depletion increases the frequency of alternative End Joining events, and generates large deletions following repair of double-strand breaks. This increase of alternative End Joining events is largely dependent on CtIP-mediated resection, indicating that it is probably related to the role of p400 in late steps of homologous recombination. Moreover, p400 depletion leads to the recruitment of poly(ADP) ribose polymerase (PARP) and DNA ligase 3 at DNA double-strand breaks, driving to selective killing by PARP inhibitors. All together these results show that p400 acts as a brake to prevent alternative End Joining-dependent genetic instability and underline its potential value as a clinical marker.
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Affiliation(s)
- Gemael-Cedrick Taty-Taty
- Université de Toulouse, UPS, LBCMCP, F-31062 Toulouse, France CNRS UMR5088, LBCMCP, F-31062 Toulouse, France
| | - Catherine Chailleux
- Université de Toulouse, UPS, LBCMCP, F-31062 Toulouse, France CNRS UMR5088, LBCMCP, F-31062 Toulouse, France
| | - Muriel Quaranta
- Université de Toulouse, UPS, LBCMCP, F-31062 Toulouse, France CNRS UMR5088, LBCMCP, F-31062 Toulouse, France
| | - Ayeong So
- Université Paris Sud, CNRS UMR8200, IGR, Villejuif, France
| | | | | | - Pascale Bertrand
- CEA DSV, UMR 967 CEA-INSERM-Université Paris Diderot-Université Paris Sud, Fontenay aux roses, France
| | - Didier Trouche
- Université de Toulouse, UPS, LBCMCP, F-31062 Toulouse, France CNRS UMR5088, LBCMCP, F-31062 Toulouse, France
| | - Yvan Canitrot
- Université de Toulouse, UPS, LBCMCP, F-31062 Toulouse, France CNRS UMR5088, LBCMCP, F-31062 Toulouse, France
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The Ku heterodimer: function in DNA repair and beyond. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2014; 763:15-29. [PMID: 25795113 DOI: 10.1016/j.mrrev.2014.06.002] [Citation(s) in RCA: 185] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 06/07/2014] [Accepted: 06/25/2014] [Indexed: 01/11/2023]
Abstract
Ku is an abundant, highly conserved DNA binding protein found in both prokaryotes and eukaryotes that plays essential roles in the maintenance of genome integrity. In eukaryotes, Ku is a heterodimer comprised of two subunits, Ku70 and Ku80, that is best characterized for its central role as the initial DNA end binding factor in the "classical" non-homologous end joining (C-NHEJ) pathway, the main DNA double-strand break (DSB) repair pathway in mammals. Ku binds double-stranded DNA ends with high affinity in a sequence-independent manner through a central ring formed by the intertwined strands of the Ku70 and Ku80 subunits. At the break, Ku directly and indirectly interacts with several C-NHEJ factors and processing enzymes, serving as the scaffold for the entire DNA repair complex. There is also evidence that Ku is involved in signaling to the DNA damage response (DDR) machinery to modulate the activation of cell cycle checkpoints and the activation of apoptosis. Interestingly, Ku is also associated with telomeres, where, paradoxically to its DNA end-joining functions, it protects the telomere ends from being recognized as DSBs, thereby preventing their recombination and degradation. Ku, together with the silent information regulator (Sir) complex is also required for transcriptional silencing through telomere position effect (TPE). How Ku associates with telomeres, whether it is through direct DNA binding, or through protein-protein interactions with other telomere bound factors remains to be determined. Ku is central to the protection of organisms through its participation in C-NHEJ to repair DSBs generated during V(D)J recombination, a process that is indispensable for the establishment of the immune response. Ku also functions to prevent tumorigenesis and senescence since Ku-deficient mice show increased cancer incidence and early onset of aging. Overall, Ku function is critical to the maintenance of genomic integrity and to proper cellular and organismal development.
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Beck C, Boehler C, Guirouilh Barbat J, Bonnet ME, Illuzzi G, Ronde P, Gauthier LR, Magroun N, Rajendran A, Lopez BS, Scully R, Boussin FD, Schreiber V, Dantzer F. PARP3 affects the relative contribution of homologous recombination and nonhomologous end-joining pathways. Nucleic Acids Res 2014; 42:5616-32. [PMID: 24598253 PMCID: PMC4027158 DOI: 10.1093/nar/gku174] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The repair of toxic double-strand breaks (DSB) is critical for the maintenance of genome integrity. The major mechanisms that cope with DSB are: homologous recombination (HR) and classical or alternative nonhomologous end joining (C-NHEJ versus A-EJ). Because these pathways compete for the repair of DSB, the choice of the appropriate repair pathway is pivotal. Among the mechanisms that influence this choice, deoxyribonucleic acid (DNA) end resection plays a critical role by driving cells to HR, while accurate C-NHEJ is suppressed. Furthermore, end resection promotes error-prone A-EJ. Increasing evidence define Poly(ADP-ribose) polymerase 3 (PARP3, also known as ARTD3) as an important player in cellular response to DSB. In this work, we reveal a specific feature of PARP3 that together with Ku80 limits DNA end resection and thereby helps in making the choice between HR and NHEJ pathways. PARP3 interacts with and PARylates Ku70/Ku80. The depletion of PARP3 impairs the recruitment of YFP-Ku80 to laser-induced DNA damage sites and induces an imbalance between BRCA1 and 53BP1. Both events result in compromised accurate C-NHEJ and a concomitant increase in DNA end resection. Nevertheless, HR is significantly reduced upon PARP3 silencing while the enhanced end resection causes mutagenic deletions during A-EJ. As a result, the absence of PARP3 confers hypersensitivity to anti-tumoral drugs generating DSB.
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Affiliation(s)
- Carole Beck
- Poly(ADP-ribosyl)ation and Genome Integrity, Laboratoire d'Excellence Medalis, Equipe labellisée Ligue Nationale Contre Le Cancer, UMR7242, Centre Nationale de la Recherche Scientifique/Université de Strasbourg, Institut de Recherche de l'Ecole de Biotechnologie de Strasbourg, 300 bld. S. Brant, BP10413, 67412 Illkirch, France
| | - Christian Boehler
- Poly(ADP-ribosyl)ation and Genome Integrity, Laboratoire d'Excellence Medalis, Equipe labellisée Ligue Nationale Contre Le Cancer, UMR7242, Centre Nationale de la Recherche Scientifique/Université de Strasbourg, Institut de Recherche de l'Ecole de Biotechnologie de Strasbourg, 300 bld. S. Brant, BP10413, 67412 Illkirch, France
| | - Josée Guirouilh Barbat
- Université Paris Sud, CNRS UMR8200, Institut de Cancérologie Gustave-Roussy, 114 rue Edouard Vaillant, 94805 Villejuif, France
| | - Marie-Elise Bonnet
- Poly(ADP-ribosyl)ation and Genome Integrity, Laboratoire d'Excellence Medalis, Equipe labellisée Ligue Nationale Contre Le Cancer, UMR7242, Centre Nationale de la Recherche Scientifique/Université de Strasbourg, Institut de Recherche de l'Ecole de Biotechnologie de Strasbourg, 300 bld. S. Brant, BP10413, 67412 Illkirch, France
| | - Giuditta Illuzzi
- Poly(ADP-ribosyl)ation and Genome Integrity, Laboratoire d'Excellence Medalis, Equipe labellisée Ligue Nationale Contre Le Cancer, UMR7242, Centre Nationale de la Recherche Scientifique/Université de Strasbourg, Institut de Recherche de l'Ecole de Biotechnologie de Strasbourg, 300 bld. S. Brant, BP10413, 67412 Illkirch, France
| | - Philippe Ronde
- Laboratoire de biophotonique et pharmacologie, UMR 7213, Centre Nationale de la Recherche Scientifique/Université de Strasbourg, Faculté de pharmacie, 74 route du Rhin, 67401 Illkirch, France
| | - Laurent R Gauthier
- CEA DSV iRCM SCSR, Laboratoire de radiopathologie, INSERM, U967, 92265 Fontenay-aux-Roses, France
| | - Najat Magroun
- Poly(ADP-ribosyl)ation and Genome Integrity, Laboratoire d'Excellence Medalis, Equipe labellisée Ligue Nationale Contre Le Cancer, UMR7242, Centre Nationale de la Recherche Scientifique/Université de Strasbourg, Institut de Recherche de l'Ecole de Biotechnologie de Strasbourg, 300 bld. S. Brant, BP10413, 67412 Illkirch, France
| | - Anbazhagan Rajendran
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA
| | - Bernard S Lopez
- Université Paris Sud, CNRS UMR8200, Institut de Cancérologie Gustave-Roussy, 114 rue Edouard Vaillant, 94805 Villejuif, France
| | - Ralph Scully
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA
| | - François D Boussin
- CEA DSV iRCM SCSR, Laboratoire de radiopathologie, INSERM, U967, 92265 Fontenay-aux-Roses, France
| | - Valérie Schreiber
- Poly(ADP-ribosyl)ation and Genome Integrity, Laboratoire d'Excellence Medalis, Equipe labellisée Ligue Nationale Contre Le Cancer, UMR7242, Centre Nationale de la Recherche Scientifique/Université de Strasbourg, Institut de Recherche de l'Ecole de Biotechnologie de Strasbourg, 300 bld. S. Brant, BP10413, 67412 Illkirch, France
| | - Françoise Dantzer
- Poly(ADP-ribosyl)ation and Genome Integrity, Laboratoire d'Excellence Medalis, Equipe labellisée Ligue Nationale Contre Le Cancer, UMR7242, Centre Nationale de la Recherche Scientifique/Université de Strasbourg, Institut de Recherche de l'Ecole de Biotechnologie de Strasbourg, 300 bld. S. Brant, BP10413, 67412 Illkirch, France
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11
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Byrne M, Wray J, Reinert B, Wu Y, Nickoloff J, Lee SH, Hromas R, Williamson E. Mechanisms of oncogenic chromosomal translocations. Ann N Y Acad Sci 2014; 1310:89-97. [PMID: 24528169 DOI: 10.1111/nyas.12370] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Chromosome translocations are caused by inappropriate religation of two DNA double-strand breaks (DSBs) in heterologous chromosomes. These DSBs can be generated by endogenous or exogenous sources. Endogenous sources of DSBs leading to translocations include inappropriate recombination activating gene (RAG) or activation-induced deaminase (AID) activity during immune receptor maturation. Endogenous DSBs can also occur at noncanonical DNA structures or at collapsed replication forks. Exogenous sources of DSBs leading to translocations include ionizing radiation (IR) and cancer chemotherapy. Spatial proximity of the heterologous chromosomes is also important for translocations. While three distinct pathways for DNA DSB repair exist, mounting evidence supports alternative nonhomologous end joining (aNHEJ) as the predominant pathway through which the majority of translocations occur. Initiated by poly (ADP-ribose) polymerase 1 (PARP1), aNHEJ is utilized less frequently in DNA DSB repair than other forms of DSB repair. We recently found that PARP1 is essential for chromosomal translocations to occur and that small molecule PARP1 inhibitors, already in clinical use, can inhibit translocations generated by IR or topoisomerase II inhibition. These data confirm the central role of PARP1 in aNHEJ-mediated chromosomal translocations and raise the possibility of using clinically available PARP1 inhibitors in patients who are at high risk for secondary oncogenic chromosomal translocations.
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Affiliation(s)
- Michael Byrne
- Department of Medicine, University of Florida College of Medicine, Gainesville, Florida
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Bétermier M, Bertrand P, Lopez BS. Is non-homologous end-joining really an inherently error-prone process? PLoS Genet 2014; 10:e1004086. [PMID: 24453986 PMCID: PMC3894167 DOI: 10.1371/journal.pgen.1004086] [Citation(s) in RCA: 280] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
DNA double-strand breaks (DSBs) are harmful lesions leading to genomic instability or diversity. Non-homologous end-joining (NHEJ) is a prominent DSB repair pathway, which has long been considered to be error-prone. However, recent data have pointed to the intrinsic precision of NHEJ. Three reasons can account for the apparent fallibility of NHEJ: 1) the existence of a highly error-prone alternative end-joining process; 2) the adaptability of canonical C-NHEJ (Ku- and Xrcc4/ligase IV-dependent) to imperfect complementary ends; and 3) the requirement to first process chemically incompatible DNA ends that cannot be ligated directly. Thus, C-NHEJ is conservative but adaptable, and the accuracy of the repair is dictated by the structure of the DNA ends rather than by the C-NHEJ machinery. We present data from different organisms that describe the conservative/versatile properties of C-NHEJ. The advantages of the adaptability/versatility of C-NHEJ are discussed for the development of the immune repertoire and the resistance to ionizing radiation, especially at low doses, and for targeted genome manipulation.
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Affiliation(s)
- Mireille Bétermier
- CNRS, Centre de Génétique Moléculaire, UPR3404, Gif-sur-Yvette, France
- CNRS, Centre de Recherches de Gif-sur-Yvette, FRC3115, Gif-sur-Yvette, France
- Université Paris-Sud, Département de Biologie, Orsay, France
| | - Pascale Bertrand
- CEA, DSV, Institut de Radiobiologie Moléculaire et Cellulaire, Laboratoire Réparation et Vieillissement, Fontenay-aux-Roses, France
- UMR 8200 CNRS, Villejuif, France
| | - Bernard S. Lopez
- Université Paris-Sud, Département de Biologie, Orsay, France
- UMR 8200 CNRS, Villejuif, France
- Institut de Cancérologie, Gustave Roussy, Villejuif, France
- * E-mail:
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The secret life of Bcl-2: Apoptosis-independent inhibition of DNA repair by Bcl-2 family members. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2012; 751:247-257. [DOI: 10.1016/j.mrrev.2012.05.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 05/25/2012] [Accepted: 05/26/2012] [Indexed: 11/22/2022]
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Shao Z, Davis AJ, Fattah KR, So S, Sun J, Lee KJ, Harrison L, Yang J, Chen DJ. Persistently bound Ku at DNA ends attenuates DNA end resection and homologous recombination. DNA Repair (Amst) 2012; 11:310-6. [PMID: 22265216 DOI: 10.1016/j.dnarep.2011.12.007] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Revised: 12/19/2011] [Accepted: 12/21/2011] [Indexed: 10/24/2022]
Abstract
DNA double strand breaks (DSBs) are repaired by non-homologous end joining (NHEJ) or homologous recombination (HR). The DNA cell cycle stage and resection of the DSB ends are two key mechanisms which are believed to push DSB repair to the HR pathway. Here, we show that the NHEJ factor Ku80 associates with DSBs in S phase, when HR is thought to be the preferred repair pathway, and its dynamics/kinetics at DSBs is similar to those observed for Ku80 in non-S phase in mammalian cells. A Ku homolog from Mycobacterium tuberculosis binds to and is retained at DSBs in S phase and was used as a tool to determine if blocking DNA ends affects end resection and HR in mammalian cells. A decrease in DNA end resection, as marked by IR-induced RPA, BrdU, and Rad51 focus formation, and HR are observed when Ku deficient rodent cells are complemented with Mt-Ku. Together, this data suggests that Ku70/80 binds to DSBs in all cell cycle stages and is likely actively displaced from DSB ends to free the DNA ends for DNA end resection and thus HR to occur.
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Affiliation(s)
- Zhengping Shao
- Division of Molecular Radiation Biology, Department of Radiation Oncology, The University of Texas Southwestern Medical Center, 2201 Inwood Rd, Dallas, TX 75390, USA
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15
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[Double strand break repair, one mechanism can hide another: alternative non-homologous end joining]. Cancer Radiother 2011; 16:1-10. [PMID: 21737335 DOI: 10.1016/j.canrad.2011.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 05/23/2011] [Accepted: 05/25/2011] [Indexed: 11/20/2022]
Abstract
DNA double strand breaks are major cytotoxic lesions encountered by the cells. They can be induced by ionizing radiation or endogenous stress and can lead to genetic instability. Two mechanisms compete for the repair of DNA double strand breaks: homologous recombination and non-homologous end joining (NHEJ). Homologous recombination requires DNA sequences homology and is initiated by single strand resection. Recently, advances have been made concerning the major steps and proteins involved in resection. NHEJ, in contrast, does not require sequence homology. The existence of a DNA double strand break repair mechanism, independent of KU and ligase IV, the key proteins of the canonical non homologous end joining pathway, has been revealed lately and named alternative non homologous end joining. The hallmarks of this highly mutagenic pathway are deletions at repair junctions and frequent use of distal microhomologies. This mechanism is also initiated by a single strand resection of the break. The aim of this review is firstly to present recent data on single strand resection, and secondly the alternative NHEJ pathway, including a discussion on the fidelity of NHEJ. Based on current knowledge, canonical NHEJ does not appear as an intrinsically mutagenic mechanism, but in contrast, as a conservative one. The structure of broken DNA ends actually dictates the quality repair of the alternative NHEJ and seems the actual responsible for the mutagenesis attributed beforehand to the canonical NHEJ. The existence of this novel DNA double strand breaks repair mechanism needs to be taken into account in the development of radiosensitizing strategies in order to optimise the efficiency of radiotherapy.
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16
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Kinetic analysis of DNA double-strand break repair pathways in Arabidopsis. DNA Repair (Amst) 2011; 10:611-9. [PMID: 21530420 DOI: 10.1016/j.dnarep.2011.04.002] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 03/30/2011] [Accepted: 04/01/2011] [Indexed: 01/19/2023]
Abstract
Double-strand breaks in genomic DNA (DSB) are potentially lethal lesions which separate parts of chromosome arms from their centromeres. Repair of DSB by recombination can generate mutations and further chromosomal rearrangements, making the regulation of recombination and the choice of recombination pathways of the highest importance. Although knowledge of recombination mechanisms has considerably advanced, the complex interrelationships and regulation of pathways are far from being fully understood. We analyse the different pathways of DSB repair acting in G2/M phase nuclei of irradiated plants, through quantitation of the kinetics of appearance and loss of γ-H2AX foci in Arabidopsis mutants. These analyses show the roles for the four major recombination pathways in post-S-phase DSB repair and that non-homologous recombination pathways constitute the major response. The data suggest a hierarchical organisation of DSB repair in these cells: C-NHEJ acts prior to B-NHEJ which can also inhibit MMEJ. Surprisingly the quadruple ku80 xrcc1 xrcc2 xpf mutant can repair DSB, although with severely altered kinetics. This repair leads to massive genetic instability with more than 50% of mitoses showing anaphase bridges following irradiation. This study thus clarifies the relationships between the different pathways of DSB repair in the living plant and points to the existence of novel DSB repair processes.
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Olsen PA, Gelazauskaite M, Randøl M, Krauss S. Analysis of illegitimate genomic integration mediated by zinc-finger nucleases: implications for specificity of targeted gene correction. BMC Mol Biol 2010; 11:35. [PMID: 20459736 PMCID: PMC2875229 DOI: 10.1186/1471-2199-11-35] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Accepted: 05/10/2010] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Formation of site specific genomic double strand breaks (DSBs), induced by the expression of a pair of engineered zinc-finger nucleases (ZFNs), dramatically increases the rates of homologous recombination (HR) between a specific genomic target and a donor plasmid. However, for the safe use of ZFN induced HR in practical applications, possible adverse effects of the technology such as cytotoxicity and genotoxicity need to be well understood. In this work, off-target activity of a pair of ZFNs has been examined by measuring the ratio between HR and illegitimate genomic integration in cells that are growing exponentially, and in cells that have been arrested in the G2/M phase. RESULTS A reporter cell line that contained consensus ZFN binding sites in an enhanced green fluorescent protein (EGFP) reporter gene was used to measure ratios between HR and non-homologous integration of a plasmid template. Both in human cells (HEK 293) containing the consensus ZFN binding sites and in cells lacking the ZFN binding sites, a 3.5 fold increase in the level of illegitimate integration was observed upon ZFN expression. Since the reporter gene containing the consensus ZFN target sites was found to be intact in cells where illegitimate integration had occurred, increased rates of illegitimate integration most likely resulted from the formation of off-target genomic DSBs. Additionally, in a fraction of the ZFN treated cells the co-occurrence of both specific HR and illegitimate integration was observed. As a mean to minimize unspecific effects, cell cycle manipulation of the target cells by induction of a transient G2/M cell cycle arrest was shown to stimulate the activity of HR while having little effect on the levels of illegitimate integration, thus resulting in a nearly eight fold increase in the ratio between the two processes. CONCLUSIONS The demonstration that ZFN expression, in addition to stimulating specific gene targeting by HR, leads to increased rates of illegitimate integration emphasizes the importance of careful characterization of ZFN treated cells. In order to reduce off-target events, reversible cell cycle arrest of the target cells in the G2/M phase is an efficient way for increasing the ratio between specific HR and illegitimate integration.
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Affiliation(s)
- Petter A Olsen
- Section for Cellular and Genetic Therapy, Institute of Microbiology, Oslo University Hospital, Rikshospitalet, Gausdadalleen 21, 0349 Oslo, Norway
- University of Oslo, 0027 Oslo, Norway
| | - Monika Gelazauskaite
- Section for Cellular and Genetic Therapy, Institute of Microbiology, Oslo University Hospital, Rikshospitalet, Gausdadalleen 21, 0349 Oslo, Norway
- University of Oslo, 0027 Oslo, Norway
| | - Markus Randøl
- Section for Cellular and Genetic Therapy, Institute of Microbiology, Oslo University Hospital, Rikshospitalet, Gausdadalleen 21, 0349 Oslo, Norway
- University of Oslo, 0027 Oslo, Norway
| | - Stefan Krauss
- Section for Cellular and Genetic Therapy, Institute of Microbiology, Oslo University Hospital, Rikshospitalet, Gausdadalleen 21, 0349 Oslo, Norway
- University of Oslo, 0027 Oslo, Norway
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Rass E, Grabarz A, Plo I, Gautier J, Bertrand P, Lopez BS. Role of Mre11 in chromosomal nonhomologous end joining in mammalian cells. Nat Struct Mol Biol 2009; 16:819-24. [PMID: 19633668 DOI: 10.1038/nsmb.1641] [Citation(s) in RCA: 248] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2009] [Accepted: 06/18/2009] [Indexed: 12/18/2022]
Abstract
Here we have used an intrachromosomal substrate to monitor the end joining of distant ends, which leads to DNA rearrangements in mammalian cells. We show that silencing Mre11 reduces the efficiency of nonhomologous end joining (NHEJ), affecting both the canonical and alternative pathways, partly in a manner that is independent of the ataxia-telangiectasia mutated kinase (ATM). Silencing of Rad50 or CtIP decreases end-joining efficiency in the same pathway as Mre11. In cells defective for Xrcc4, the MRE11-RAD50-NBS1 (MRN) complex inhibitor MIRIN decreases end-joining frequencies, demonstrating a role for MRN in alternative NHEJ. Consistently, MIRIN sensitizes both complemented and NHEJ-defective cells to ionizing radiation. Conversely, overexpression of Mre11 stimulates the resection of single-stranded DNA and increases alternative end joining, through a mechanism that requires Mre11's nuclease activity, but in an ATM-independent manner. These data demonstrate that, in addition to its role in ATM activation, Mre11 can favor alternative NHEJ through its nuclease activity.
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Affiliation(s)
- Emilie Rass
- Unité mixte de recherche 217, Centre National de la Recherche Scientifique-Commissariat à l'Energie Atomique, Equipe labellisée LA LIGUE 2008, Institut de Radiobiologie Cellulaire et Moléculaire, Fontenay-aux-Roses, France
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Hsiao SJ, Smith S. Sister telomeres rendered dysfunctional by persistent cohesion are fused by NHEJ. ACTA ACUST UNITED AC 2009; 184:515-26. [PMID: 19221198 PMCID: PMC2654126 DOI: 10.1083/jcb.200810132] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Telomeres protect chromosome ends from being viewed as double-strand breaks and from eliciting a DNA damage response. Deprotection of chromosome ends occurs when telomeres become critically short because of replicative attrition or inhibition of TRF2. In this study, we report a novel form of deprotection that occurs exclusively after DNA replication in S/G2 phase of the cell cycle. In cells deficient in the telomeric poly(adenosine diphosphate ribose) polymerase tankyrase 1, sister telomere resolution is blocked. Unexpectedly, cohered sister telomeres become deprotected and are inappropriately fused. In contrast to telomeres rendered dysfunctional by TRF2, which engage in chromatid fusions predominantly between chromatids from different chromosomes (Bailey, S.M., M.N. Cornforth, A. Kurimasa, D.J. Chen, and E.H. Goodwin. 2001. Science. 293:2462–2465; Smogorzewska, A., J. Karlseder, H. Holtgreve-Grez, A. Jauch, and T. de Lange. 2002. Curr. Biol. 12:1635–1644), telomeres rendered dysfunctional by tankyrase 1 engage in chromatid fusions almost exclusively between sister chromatids. We show that cohered sister telomeres are fused by DNA ligase IV–mediated nonhomologous end joining. These results demonstrate that the timely removal of sister telomere cohesion is essential for the formation of a protective structure at chromosome ends after DNA replication in S/G2 phase of the cell cycle.
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Affiliation(s)
- Susan J Hsiao
- Molecular Pathogenesis Program, The Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
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Konishi A, de Lange T. Cell cycle control of telomere protection and NHEJ revealed by a ts mutation in the DNA-binding domain of TRF2. Genes Dev 2008; 22:1221-30. [PMID: 18451109 DOI: 10.1101/gad.1634008] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
TRF2 is a component of shelterin, the telomere-specific protein complex that prevents DNA damage signaling and inappropriate repair at the natural ends of mammalian chromosomes. We describe a temperature-sensitive (ts) mutation in the Myb/SANT DNA-binding domain of TRF2 that allows controlled and reversible telomere deprotection. At 32 degrees C, TRF2ts was functional and rescued the lethality of TRF2 deletion from conditional TRF2(F/-) mouse embryonic fibroblasts (MEFs). When shifted to the nonpermissive temperature (37 degrees C), TRF2ts cells showed extensive telomere damage resulting in activation of the ATM kinase and nonhomologous end-joining (NHEJ) of chromosome ends. The inactivation of TRF2ts at 37 degrees C was rapid and reversible, permitting induction of short periods (3-6 h) of telomere dysfunction in the G0, G1, and S/G2 phases of the cell cycle. The results indicate that both the induction of telomere dysfunction and the re-establishment of the protected state can take place throughout interphase. In contrast, the processing of dysfunctional telomeres by NHEJ occurred primarily in G1, being repressed in S/G2 in a cyclin-dependent kinase (CDK)-dependent manner.
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Affiliation(s)
- Akimitsu Konishi
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York 10065, USA
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