1
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Ben-Tov D, Mafessoni F, Cucuy A, Honig A, Melamed-Bessudo C, Levy AA. Uncovering the dynamics of precise repair at CRISPR/Cas9-induced double-strand breaks. Nat Commun 2024; 15:5096. [PMID: 38877047 PMCID: PMC11178868 DOI: 10.1038/s41467-024-49410-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 06/05/2024] [Indexed: 06/16/2024] Open
Abstract
CRISPR/Cas9 is widely used for precise mutagenesis through targeted DNA double-strand breaks (DSBs) induction followed by error-prone repair. A better understanding of this process requires measuring the rates of cutting, error-prone, and precise repair, which have remained elusive so far. Here, we present a molecular and computational toolkit for multiplexed quantification of DSB intermediates and repair products by single-molecule sequencing. Using this approach, we characterize the dynamics of DSB induction, processing and repair at endogenous loci along a 72 h time-course in tomato protoplasts. Combining this data with kinetic modeling reveals that indel accumulation is determined by the combined effect of the rates of DSB induction processing of broken ends, and precise versus error repair. In this study, 64-88% of the molecules were cleaved in the three targets analyzed, while indels ranged between 15-41%. Precise repair accounts for most of the gap between cleavage and error repair, representing up to 70% of all repair events. Altogether, this system exposes flux in the DSB repair process, decoupling induction and repair dynamics, and suggesting an essential role of high-fidelity repair in limiting the efficiency of CRISPR-mediated mutagenesis.
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Affiliation(s)
- Daniela Ben-Tov
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Fabrizio Mafessoni
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Amit Cucuy
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Arik Honig
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Cathy Melamed-Bessudo
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel.
| | - Avraham A Levy
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel.
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2
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Stinson BM, Carney SM, Walter JC, Loparo JJ. Structural role for DNA Ligase IV in promoting the fidelity of non-homologous end joining. Nat Commun 2024; 15:1250. [PMID: 38341432 PMCID: PMC10858965 DOI: 10.1038/s41467-024-45553-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 01/25/2024] [Indexed: 02/12/2024] Open
Abstract
Nonhomologous end joining (NHEJ), the primary pathway of vertebrate DNA double-strand-break (DSB) repair, directly re-ligates broken DNA ends. Damaged DSB ends that cannot be immediately re-ligated are modified by NHEJ processing enzymes, including error-prone polymerases and nucleases, to enable ligation. However, DSB ends that are initially compatible for re-ligation are typically joined without end processing. As both ligation and end processing occur in the short-range (SR) synaptic complex that closely aligns DNA ends, it remains unclear how ligation of compatible ends is prioritized over end processing. In this study, we identify structural interactions of the NHEJ-specific DNA Ligase IV (Lig4) within the SR complex that prioritize ligation and promote NHEJ fidelity. Mutational analysis demonstrates that Lig4 must bind DNA ends to form the SR complex. Furthermore, single-molecule experiments show that a single Lig4 binds both DNA ends at the instant of SR synapsis. Thus, Lig4 is poised to ligate compatible ends upon initial formation of the SR complex before error-prone processing. Our results provide a molecular basis for the fidelity of NHEJ.
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Affiliation(s)
- Benjamin M Stinson
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA
- Howard Hughes Medical Institute, Boston, MA, 02115, USA
| | - Sean M Carney
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA
| | - Johannes C Walter
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA.
- Howard Hughes Medical Institute, Boston, MA, 02115, USA.
| | - Joseph J Loparo
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA.
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3
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Loparo JJ. Holding it together: DNA end synapsis during non-homologous end joining. DNA Repair (Amst) 2023; 130:103553. [PMID: 37572577 PMCID: PMC10530278 DOI: 10.1016/j.dnarep.2023.103553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 08/04/2023] [Accepted: 08/06/2023] [Indexed: 08/14/2023]
Abstract
DNA double strand breaks (DSBs) are common lesions whose misrepair are drivers of oncogenic transformations. The non-homologous end joining (NHEJ) pathway repairs the majority of these breaks in vertebrates by directly ligating DNA ends back together. Upon formation of a DSB, a multiprotein complex is assembled on DNA ends which tethers them together within a synaptic complex. Synapsis is a critical step of the NHEJ pathway as loss of synapsis can result in mispairing of DNA ends and chromosome translocations. As DNA ends are commonly incompatible for ligation, the NHEJ machinery must also process ends to enable rejoining. This review describes how recent progress in single-molecule approaches and cryo-EM have advanced our molecular understanding of DNA end synapsis during NHEJ and how synapsis is coordinated with end processing to determine the fidelity of repair.
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Affiliation(s)
- Joseph J Loparo
- Dept. of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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4
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González-Arzola K, Díaz-Quintana A. Mitochondrial Factors in the Cell Nucleus. Int J Mol Sci 2023; 24:13656. [PMID: 37686461 PMCID: PMC10563088 DOI: 10.3390/ijms241713656] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 08/31/2023] [Accepted: 08/31/2023] [Indexed: 09/10/2023] Open
Abstract
The origin of eukaryotic organisms involved the integration of mitochondria into the ancestor cell, with a massive gene transfer from the original proteobacterium to the host nucleus. Thus, mitochondrial performance relies on a mosaic of nuclear gene products from a variety of genomes. The concerted regulation of their synthesis is necessary for metabolic housekeeping and stress response. This governance involves crosstalk between mitochondrial, cytoplasmic, and nuclear factors. While anterograde and retrograde regulation preserve mitochondrial homeostasis, the mitochondria can modulate a wide set of nuclear genes in response to an extensive variety of conditions, whose response mechanisms often merge. In this review, we summarise how mitochondrial metabolites and proteins-encoded either in the nucleus or in the organelle-target the cell nucleus and exert different actions modulating gene expression and the chromatin state, or even causing DNA fragmentation in response to common stress conditions, such as hypoxia, oxidative stress, unfolded protein stress, and DNA damage.
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Affiliation(s)
- Katiuska González-Arzola
- Centro Andaluz de Biología Molecular y Medicina Regenerativa—CABIMER, Consejo Superior de Investigaciones Científicas—Universidad de Sevilla—Universidad Pablo de Olavide, 41092 Seville, Spain
- Departamento de Bioquímica Vegetal y Biología Molecular, Universidad de Sevilla, 41012 Seville, Spain
| | - Antonio Díaz-Quintana
- Departamento de Bioquímica Vegetal y Biología Molecular, Universidad de Sevilla, 41012 Seville, Spain
- Instituto de Investigaciones Químicas—cicCartuja, Universidad de Sevilla—C.S.I.C, 41092 Seville, Spain
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5
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Li F, Mladenov E, Sun Y, Soni A, Stuschke M, Timmermann B, Iliakis G. Low CDK Activity and Enhanced Degradation by APC/C CDH1 Abolishes CtIP Activity and Alt-EJ in Quiescent Cells. Cells 2023; 12:1530. [PMID: 37296650 PMCID: PMC10252496 DOI: 10.3390/cells12111530] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 05/26/2023] [Accepted: 05/27/2023] [Indexed: 06/12/2023] Open
Abstract
Alt-EJ is an error-prone DNA double-strand break (DSBs) repair pathway coming to the fore when first-line repair pathways, c-NHEJ and HR, are defective or fail. It is thought to benefit from DNA end-resection-a process whereby 3' single-stranded DNA-tails are generated-initiated by the CtIP/MRE11-RAD50-NBS1 (MRN) complex and extended by EXO1 or the BLM/DNA2 complex. The connection between alt-EJ and resection remains incompletely characterized. Alt-EJ depends on the cell cycle phase, is at maximum in G2-phase, substantially reduced in G1-phase and almost undetectable in quiescent, G0-phase cells. The mechanism underpinning this regulation remains uncharacterized. Here, we compare alt-EJ in G1- and G0-phase cells exposed to ionizing radiation (IR) and identify CtIP-dependent resection as the key regulator. Low levels of CtIP in G1-phase cells allow modest resection and alt-EJ, as compared to G2-phase cells. Strikingly, CtIP is undetectable in G0-phase cells owing to APC/C-mediated degradation. The suppression of CtIP degradation with bortezomib or CDH1-depletion rescues CtIP and alt-EJ in G0-phase cells. CtIP activation in G0-phase cells also requires CDK-dependent phosphorylation by any available CDK but is restricted to CDK4/6 at the early stages of the normal cell cycle. We suggest that suppression of mutagenic alt-EJ in G0-phase is a mechanism by which cells of higher eukaryotes maintain genomic stability in a large fraction of non-cycling cells in their organisms.
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Affiliation(s)
- Fanghua Li
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (F.L.); (E.M.); (Y.S.); (A.S.)
- Department of Particle Therapy, University Hospital Essen, West German Proton Therapy Centre Essen (WPE), West German Cancer Center (WTZ), German Cancer Consortium (DKTK), 45147 Essen, Germany;
| | - Emil Mladenov
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (F.L.); (E.M.); (Y.S.); (A.S.)
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
| | - Yanjie Sun
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (F.L.); (E.M.); (Y.S.); (A.S.)
- Department of Particle Therapy, University Hospital Essen, West German Proton Therapy Centre Essen (WPE), West German Cancer Center (WTZ), German Cancer Consortium (DKTK), 45147 Essen, Germany;
| | - Aashish Soni
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (F.L.); (E.M.); (Y.S.); (A.S.)
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
| | - Martin Stuschke
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
- German Cancer Consortium (DKTK), Partner Site University Hospital Essen, German Cancer Research Center (DKFZ), 45147 Essen, Germany
| | - Beate Timmermann
- Department of Particle Therapy, University Hospital Essen, West German Proton Therapy Centre Essen (WPE), West German Cancer Center (WTZ), German Cancer Consortium (DKTK), 45147 Essen, Germany;
- German Cancer Consortium (DKTK), Partner Site University Hospital Essen, German Cancer Research Center (DKFZ), 45147 Essen, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (F.L.); (E.M.); (Y.S.); (A.S.)
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
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6
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Al-Zain AM, Symington LS. The dark side of homology-directed repair. DNA Repair (Amst) 2021; 106:103181. [PMID: 34311272 DOI: 10.1016/j.dnarep.2021.103181] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 07/16/2021] [Accepted: 07/16/2021] [Indexed: 10/20/2022]
Abstract
DNA double strand breaks (DSB) are cytotoxic lesions that can lead to genome rearrangements and genomic instability, which are hallmarks of cancer. The two main DSB repair pathways are non-homologous end joining and homologous recombination (HR). While HR is generally highly accurate, it has the potential for rearrangements that occur directly or through intermediates generated during the repair process. Whole genome sequencing of cancers has revealed numerous types of structural rearrangement signatures that are often indicative of repair mediated by sequence homology. However, it can be challenging to delineate repair mechanisms from sequence analysis of rearrangement end products from cancer genomes, or even model systems, because the same rearrangements can be generated by different pathways. Here, we review homology-directed repair pathways and their consequences. Exploring those pathways can lead to a greater understanding of rearrangements that occur in cancer cells.
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Affiliation(s)
- Amr M Al-Zain
- Program in Biological Sciences, Columbia University, New York, NY, 10027, United States; Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, United States
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, United States; Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY, 10032, United States.
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7
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Stinson BM, Loparo JJ. Repair of DNA Double-Strand Breaks by the Nonhomologous End Joining Pathway. Annu Rev Biochem 2021; 90:137-164. [PMID: 33556282 DOI: 10.1146/annurev-biochem-080320-110356] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
DNA double-strand breaks pose a serious threat to genome stability. In vertebrates, these breaks are predominantly repaired by nonhomologous end joining (NHEJ), which pairs DNA ends in a multiprotein synaptic complex to promote their direct ligation. NHEJ is a highly versatile pathway that uses an array of processing enzymes to modify damaged DNA ends and enable their ligation. The mechanisms of end synapsis and end processing have important implications for genome stability. Rapid and stable synapsis is necessary to limit chromosome translocations that result from the mispairing of DNA ends. Furthermore, end processing must be tightly regulated to minimize mutations at the break site. Here, we review our current mechanistic understanding of vertebrate NHEJ, with a particular focus on end synapsis and processing.
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Affiliation(s)
- Benjamin M Stinson
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA; ,
| | - Joseph J Loparo
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA; ,
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8
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Panigrahi R, Glover JNM. Structural insights into DNA double-strand break signaling. Biochem J 2021; 478:135-156. [PMID: 33439989 DOI: 10.1042/bcj20200066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 12/10/2020] [Accepted: 12/15/2020] [Indexed: 12/14/2022]
Abstract
Genomic integrity is most threatened by double-strand breaks, which, if left unrepaired, lead to carcinogenesis or cell death. The cell generates a network of protein-protein signaling interactions that emanate from the DNA damage which are now recognized as a rich basis for anti-cancer therapy development. Deciphering the structures of signaling proteins has been an uphill task owing to their large size and complex domain organization. Recent advances in mammalian protein expression/purification and cryo-EM-based structure determination have led to significant progress in our understanding of these large multidomain proteins. This review is an overview of the structural principles that underlie some of the key signaling proteins that function at the double-strand break site. We also discuss some plausible ideas that could be considered for future structural approaches to visualize and build a more complete understanding of protein dynamics at the break site.
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Affiliation(s)
- Rashmi Panigrahi
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - J N Mark Glover
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
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9
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Carballar R, Martínez-Láinez JM, Samper B, Bru S, Bállega E, Mirallas O, Ricco N, Clotet J, Jiménez J. CDK-mediated Yku80 Phosphorylation Regulates the Balance Between Non-homologous End Joining (NHEJ) and Homologous Directed Recombination (HDR). J Mol Biol 2020; 432:166715. [PMID: 33217428 DOI: 10.1016/j.jmb.2020.11.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 11/04/2020] [Accepted: 11/11/2020] [Indexed: 11/28/2022]
Abstract
There are two major pathways for repairing DNA double-strand breaks (DSBs): homologous directed recombination (HDR) and non-homologous end-joining (NHEJ). While NHEJ functions throughout the cell cycle, HDR is only possible during S/G2 phases, suggesting that there are cell cycle-specific mechanisms regulating the balance between the two repair systems. The regulation exerted by CDKs on HDR has been extensively demonstrated, and here we present evidence that the CDK Pho85, in association with the G1 cyclin Pcl1, phosphorylates Yku80 on Ser 623 to regulate NHEJ activity. Cells bearing a non-phosphorylatable version of Yku80 show increased NHEJ and reduced HDR activity. Accordingly, yku80S623A cells present diminished viability upon treatment with the DSB-producer bleomycin, specifically in the G2 phase of the cell cycle. Interestingly, the mutation of the equivalent residue in human Ku80 increases sensitivity to bleomycin in several cancer cell lines, suggesting that this mechanism is conserved in humans. Altogether, our results reveal a new mechanism whereby G1-CDKs mediate the choice between HDR and NHEJ repair pathways, putting the error prone NHEJ on a leash and enabling error free HDR in G2 when homologous sequences are available.
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Affiliation(s)
- Reyes Carballar
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Joan M Martínez-Láinez
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Bàrbara Samper
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Samuel Bru
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Elisabet Bállega
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Oriol Mirallas
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Natalia Ricco
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Josep Clotet
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain.
| | - Javier Jiménez
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain.
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10
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Fang T, Zhang Y, Chang VY, Roos M, Termini CM, Signaevskaia L, Quarmyne M, Lin PK, Pang A, Kan J, Yan X, Javier A, Pohl K, Zhao L, Scott P, Himburg HA, Chute JP. Epidermal growth factor receptor-dependent DNA repair promotes murine and human hematopoietic regeneration. Blood 2020; 136:441-454. [PMID: 32369572 PMCID: PMC7378456 DOI: 10.1182/blood.2020005895] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 04/13/2020] [Indexed: 02/07/2023] Open
Abstract
Chemotherapy and irradiation cause DNA damage to hematopoietic stem cells (HSCs), leading to HSC depletion and dysfunction and the risk of malignant transformation over time. Extrinsic regulation of HSC DNA repair is not well understood, and therapies to augment HSC DNA repair following myelosuppression remain undeveloped. We report that epidermal growth factor receptor (EGFR) regulates DNA repair in HSCs following irradiation via activation of the DNA-dependent protein kinase-catalytic subunit (DNA-PKcs) and nonhomologous end joining (NHEJ). We show that hematopoietic regeneration in vivo following total body irradiation is dependent upon EGFR-mediated repair of DNA damage via activation of DNA-PKcs. Conditional deletion of EGFR in hematopoietic stem and progenitor cells (HSPCs) significantly decreased DNA-PKcs activity following irradiation, causing increased HSC DNA damage and depressed HSC recovery over time. Systemic administration of epidermal growth factor (EGF) promoted HSC DNA repair and rapid hematologic recovery in chemotherapy-treated mice and had no effect on acute myeloid leukemia growth in vivo. Further, EGF treatment drove the recovery of human HSCs capable of multilineage in vivo repopulation following radiation injury. Whole-genome sequencing analysis revealed no increase in coding region mutations in HSPCs from EGF-treated mice, but increased intergenic copy number variant mutations were detected. These studies demonstrate that EGF promotes HSC DNA repair and hematopoietic regeneration in vivo via augmentation of NHEJ. EGF has therapeutic potential to promote human hematopoietic regeneration, and further studies are warranted to assess long-term hematopoietic effects.
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Affiliation(s)
| | | | - Vivian Y Chang
- Pediatric Hematology/Oncology
- Jonsson Comprehensive Cancer Center
| | - Martina Roos
- Jonsson Comprehensive Cancer Center
- Division of Hematology/Oncology, Department of Medicine
- Broad Stem Cell Research Center, and
| | | | | | | | - Paulina K Lin
- Division of Hematology/Oncology, Department of Medicine
| | - Amara Pang
- Division of Hematology/Oncology, Department of Medicine
| | - Jenny Kan
- Division of Hematology/Oncology, Department of Medicine
| | - Xiao Yan
- Department of Molecular and Medical Pharmacology
| | - Anna Javier
- Division of Hematology/Oncology, Department of Medicine
| | | | - Liman Zhao
- Division of Hematology/Oncology, Department of Medicine
| | - Peter Scott
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA
| | | | - John P Chute
- Jonsson Comprehensive Cancer Center
- Division of Hematology/Oncology, Department of Medicine
- Broad Stem Cell Research Center, and
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11
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Xu Z, Zhang J, Cheng X, Tang Y, Gong Z, Gu M, Yu H. COM1, a factor of alternative non-homologous end joining, lagging behind the classic non-homologous end joining pathway in rice somatic cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:140-153. [PMID: 32022972 DOI: 10.1111/tpj.14715] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 01/15/2020] [Accepted: 01/29/2020] [Indexed: 06/10/2023]
Abstract
The role of rice (Oryza sativa) COM1 in meiotic homologous recombination (HR) is well understood, but its part in somatic double-stranded break (DSB) repair remains unclear. Here, we show that for rice plants COM1 conferred tolerance against DNA damage caused by the chemicals bleomycin and mitomycin C, while the COM1 mutation did not compromise HR efficiencies and HR factor (RAD51 and RAD51 paralogues) localization to irradiation-induced DSBs. Similar retarded growth at the post-germination stage was observed in the com1-2 mre11 double mutant and the mre11 single mutant, while combined mutations in COM1 with the HR pathway gene (RAD51C) or classic non-homologous end joining (NHEJ) pathway genes (KU70, KU80, and LIG4) caused more phenotypic defects. In response to γ-irradiation, COM1 was loaded normally onto DSBs in the ku70 mutant, but could not be properly loaded in the MRE11RNAi plant and in the wortmannin-treated wild-type plant. Under non-irradiated conditions, more DSB sites were occupied by factors (MRE11, COM1, and LIG4) than RAD51 paralogues (RAD51B, RAD51C, and XRCC3) in the nucleus of wild-type; protein loading of COM1 and XRCC3 was increased in the ku70 mutant. Therefore, quite differently to its role for HR in meiocytes, rice COM1 specifically acts in an alternative NHEJ pathway in somatic cells, based on the Mre11-Rad50-Nbs1 (MRN) complex and facilitated by PI3K-like kinases. NHEJ factors, not HR factors, preferentially load onto endogenous DSBs, with KU70 restricting DSB localization of COM1 and XRCC3 in plant somatic cells.
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Affiliation(s)
- Zhan Xu
- Key Laboratory of Plant Functional Genomics of Ministry of Education/Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou, 225009, China
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China
| | - Jianxiang Zhang
- Key Laboratory of Plant Functional Genomics of Ministry of Education/Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou, 225009, China
| | - Xinjie Cheng
- Key Laboratory of Plant Functional Genomics of Ministry of Education/Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou, 225009, China
| | - Yujie Tang
- Key Laboratory of Plant Functional Genomics of Ministry of Education/Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou, 225009, China
| | - Zhiyun Gong
- Key Laboratory of Plant Functional Genomics of Ministry of Education/Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou, 225009, China
| | - Minghong Gu
- Key Laboratory of Plant Functional Genomics of Ministry of Education/Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou, 225009, China
| | - Hengxiu Yu
- Key Laboratory of Plant Functional Genomics of Ministry of Education/Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou, 225009, China
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12
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Liu X, Jiang Y, Nowak B, Ichikawa S, Ohtawa M, Matsuda A, Plunkett W. Repair of DNA damage induced by the novel nucleoside analogue CNDAG through homologous recombination. Cancer Chemother Pharmacol 2020; 85:661-672. [PMID: 32072218 DOI: 10.1007/s00280-020-04035-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 01/21/2020] [Indexed: 02/03/2023]
Abstract
PURPOSE We postulate that the deoxyguanosine analogue CNDAG [9-(2-C-cyano-2-deoxy-1-β-D-arabino-pentofuranosyl)guanine] likely causes a single-strand break after incorporation into DNA, similar to the action of its cytosine congener CNDAC, and that subsequent DNA replication across the unrepaired nick would generate a double-strand break. This study aimed at identifying cellular responses and repair mechanisms for CNDAG prodrugs, 2-amino-9-(2-C-cyano-2-deoxy-1-β-D-arabino-pentofuranosyl)-6-methoxy purine (6-OMe) and 9-(2-C-cyano-2-deoxy-1-β-D-arabino-pentofuranosyl)-2,6-diaminopurine (6-NH2). Each compound is a substrate for adenosine deaminase, the action of which generates CNDAG. METHODS Growth inhibition assay, clonogenic survival assay, immunoblotting, and cytogenetic analyses (chromosomal aberrations and sister chromatid exchanges) were used to investigate the impact of CNDAG on cell lines. RESULTS The 6-NH2 derivative was selectively potent in T cell malignant cell lines. Both prodrugs caused increased phosphorylation of ATM and its downstream substrates Chk1, Chk2, SMC1, NBS1, and H2AX, indicating activation of ATM-dependent DNA damage response pathways. In contrast, there was no increase in phosphorylation of DNA-PKcs, which participates in repair of double-strand breaks by non-homologous end-joining. Deficiency in ATM, RAD51D, XRCC3, BRCA2, and XPF, but not DNA-PK or p53, conferred significant clonogenic sensitivity to CNDAG or the prodrugs. Moreover, hamster cells lacking XPF acquired remarkably more chromosomal aberrations after incubation for two cell cycle times with CNDAG 6-NH2, compared to the wild type. Furthermore, CNDAG 6-NH2 induced greater levels of sister chromatid exchanges in wild-type cells exposed for two cycles than those for one cycle, consistent with increased double-strand breaks after a second S phase. CONCLUSION CNDAG-induced double-strand breaks are repaired mainly through homologous recombination.
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Affiliation(s)
- Xiaojun Liu
- Department of Experimental Therapeutics, The University of Texas M. D. Anderson Cancer Center, Houston, TX, 77054, USA
- School of Health Professions, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Yingjun Jiang
- Department of Experimental Therapeutics, The University of Texas M. D. Anderson Cancer Center, Houston, TX, 77054, USA
| | - Billie Nowak
- Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Satoshi Ichikawa
- Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Masaki Ohtawa
- Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Akira Matsuda
- Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - William Plunkett
- Department of Experimental Therapeutics, The University of Texas M. D. Anderson Cancer Center, Houston, TX, 77054, USA.
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Miller DE. Synaptonemal Complex-Deficient Drosophila melanogaster Females Exhibit Rare DSB Repair Events, Recurrent Copy-Number Variation, and an Increased Rate of de Novo Transposable Element Movement. G3 (BETHESDA, MD.) 2020; 10:525-537. [PMID: 31882405 PMCID: PMC7003089 DOI: 10.1534/g3.119.400853] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Accepted: 12/23/2019] [Indexed: 01/11/2023]
Abstract
Genetic stability depends on the maintenance of a variety of chromosome structures and the precise repair of DNA breaks. During meiosis, programmed double-strand breaks (DSBs) made in prophase I are normally repaired as gene conversions or crossovers. DSBs can also be made by other mechanisms, such as the movement of transposable elements (TEs), which must also be resolved. Incorrect repair of these DNA lesions can lead to mutations, copy-number changes, translocations, and/or aneuploid gametes. In Drosophila melanogaster, as in most organisms, meiotic DSB repair occurs in the presence of a rapidly evolving multiprotein structure called the synaptonemal complex (SC). Here, whole-genome sequencing is used to investigate the fate of meiotic DSBs in D. melanogaster mutant females lacking functional SC, to assay for de novo CNV formation, and to examine the role of the SC in transposable element movement in flies. The data indicate that, in the absence of SC, copy-number variation still occurs and meiotic DSB repair by gene conversion occurs infrequently. Remarkably, an 856-kilobase de novo CNV was observed in two unrelated individuals of different genetic backgrounds and was identical to a CNV recovered in a previous wild-type study, suggesting that recurrent formation of large CNVs occurs in Drosophila. In addition, the rate of novel TE insertion was markedly higher than wild type in one of two SC mutants tested, suggesting that SC proteins may contribute to the regulation of TE movement and insertion in the genome. Overall, this study provides novel insight into the role that the SC plays in genome stability and provides clues as to why the sequence, but not structure, of SC proteins is rapidly evolving.
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Affiliation(s)
- Danny E Miller
- Division of Medical Genetics, Department of Medicine, and
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington 98105, and
- Seattle Children's Hospital, Seattle, Washington 98105
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14
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Chauhan V, Sherman S, Said Z, Yauk CL, Stainforth R. A case example of a radiation-relevant adverse outcome pathway to lung cancer. Int J Radiat Biol 2020; 97:68-84. [PMID: 31846388 DOI: 10.1080/09553002.2019.1704913] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Adverse outcome pathways (AOPs) describe how a measurable sequence of key events, beginning from a molecular initiator, can lead to an adverse outcome of relevance to risk assessment. An AOP is modular by design, comprised of four main components: (1) a Molecular Initiating Event (MIE), (2) Key Events (KEs), (3) Key Event Relationships (KERs) and (4) an Adverse Outcome (AO). PURPOSE Here, we illustrate the utility of the AOP concept through a case example in the field of ionizing radiation, using the Organisation for Economic Cooperation and Development (OECD) Users' Handbook. This AOP defines a classic targeted response to a radiation insult with an AO of lung cancer that is relevant to radon gas exposure. MATERIALS AND METHODS To build this AOP, over 500 papers were reviewed and categorized based on the modified Bradford-Hill Criteria. Data-rich key events from the MIE, to several measurable KEs and KERs related to DNA damage response/repair were identified. RESULTS The components for this AOP begin with direct deposition of energy as the MIE. Energy deposited into a cell can lead to multiple ionization events to targets such as DNA. This energy can damage DNA leading to double-strand breaks (DSBs) (KE1), this will initiate repair activation (KE2) in higher eukaryotes through mechanisms that are quick and efficient, but error-prone. If DSBs occur in regions of the DNA transcribing critical genes, then mutations (KE3) generated through faulty repair may alter the function of these genes or may cause chromosomal aberrations (KE4). This can impact cellular pathways such as cell growth, cell cycling and then cellular proliferation (KE5). This will form hyperplasia in lung cells, leading eventually to lung cancer (AO) induction and metastasis. The weight of evidence for the KERs was built using biological plausibility, incidence concordance, dose-response, time-response and essentiality studies. The uncertainties and inconsistencies surrounding this AOP are centered on dose-response relationships associated with dose, dose-rates and radiation quality. CONCLUSION Overall, the AOP framework provided an effective means to organize the scientific knowledge surrounding the KERs and identify those with strong dose-response relationships and those with inconsistencies. This case study is an example of how the AOP methodology can be applied to sources of radiation to help support areas of risk assessment.
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Affiliation(s)
- Vinita Chauhan
- Consumer and Clinical Radiation Protection Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Canada
| | - Samantha Sherman
- Consumer and Clinical Radiation Protection Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Canada
| | - Zakaria Said
- Consumer and Clinical Radiation Protection Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Canada
| | - Carole L Yauk
- Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Canada
| | - Robert Stainforth
- Consumer and Clinical Radiation Protection Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Canada
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15
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PerezGrovas-Saltijeral A, Ochoa-Morales A, Miranda-Duarte A, Martínez-Ruano L, Jara-Prado A, Camacho-Molina A, Hidalgo-Bravo A. Telomere length analysis on leukocytes derived from patients with Huntington Disease. Mech Ageing Dev 2020; 185:111189. [DOI: 10.1016/j.mad.2019.111189] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 10/30/2019] [Accepted: 11/19/2019] [Indexed: 02/03/2023]
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16
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Stinson BM, Moreno AT, Walter JC, Loparo JJ. A Mechanism to Minimize Errors during Non-homologous End Joining. Mol Cell 2019; 77:1080-1091.e8. [PMID: 31862156 DOI: 10.1016/j.molcel.2019.11.018] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 10/09/2019] [Accepted: 11/22/2019] [Indexed: 01/15/2023]
Abstract
Enzymatic processing of DNA underlies all DNA repair, yet inappropriate DNA processing must be avoided. In vertebrates, double-strand breaks are repaired predominantly by non-homologous end joining (NHEJ), which directly ligates DNA ends. NHEJ has the potential to be highly mutagenic because it uses DNA polymerases, nucleases, and other enzymes that modify incompatible DNA ends to allow their ligation. Using frog egg extracts that recapitulate NHEJ, we show that end processing requires the formation of a "short-range synaptic complex" in which DNA ends are closely aligned in a ligation-competent state. Furthermore, single-molecule imaging directly demonstrates that processing occurs within the short-range complex. This confinement of end processing to a ligation-competent complex ensures that DNA ends undergo ligation as soon as they become compatible, thereby minimizing mutagenesis. Our results illustrate how the coordination of enzymatic catalysis with higher-order structural organization of substrate maximizes the fidelity of DNA repair.
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Affiliation(s)
- Benjamin M Stinson
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Andrew T Moreno
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Johannes C Walter
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA.
| | - Joseph J Loparo
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
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17
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Köcher S, Beyer B, Lange T, Nordquist L, Volquardsen J, Burdak‐Rothkamm S, Schlomm T, Petersen C, Rothkamm K, Mansour WY. A functional
ex vivo
assay to detect PARP1‐EJ repair and radiosensitization by PARP‐inhibitor in prostate cancer. Int J Cancer 2019; 144:1685-1696. [DOI: 10.1002/ijc.32018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 11/13/2018] [Indexed: 12/14/2022]
Affiliation(s)
- Sabrina Köcher
- Laboratory of Radiobiology and Experimental RadiooncologyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Burkhard Beyer
- Martini‐Klinik, Prostate Cancer CenterUniversity Medical Hamburg Eppendorf Hamburg Germany
| | - Tobias Lange
- Institute of AnatomyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Lena Nordquist
- Laboratory of Radiobiology and Experimental RadiooncologyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Jennifer Volquardsen
- Laboratory of Radiobiology and Experimental RadiooncologyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Susanne Burdak‐Rothkamm
- Department of Radiotherapy and RadiooncologyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Thorsten Schlomm
- Martini‐Klinik, Prostate Cancer CenterUniversity Medical Hamburg Eppendorf Hamburg Germany
| | - Cordula Petersen
- Department of Radiotherapy and RadiooncologyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Kai Rothkamm
- Laboratory of Radiobiology and Experimental RadiooncologyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Wael Yassin Mansour
- Laboratory of Radiobiology and Experimental RadiooncologyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
- Department of Tumor BiologyNational Cancer Institute, Cairo University Cairo Egypt
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18
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Sulkowski PL, Scanlon SE, Oeck S, Glazer PM. PTEN Regulates Nonhomologous End Joining By Epigenetic Induction of NHEJ1/XLF. Mol Cancer Res 2018; 16:1241-1254. [PMID: 29739874 DOI: 10.1158/1541-7786.mcr-17-0581] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 03/23/2018] [Accepted: 04/23/2018] [Indexed: 11/16/2022]
Abstract
DNA double-strand breaks (DSB) are the most cytotoxic DNA lesions, and up to 90% of DSBs require repair by nonhomologous end joining (NHEJ). Functional and genomic analyses of patient-derived melanomas revealed that PTEN loss is associated with NHEJ deficiency. In PTEN-null melanomas, PTEN complementation rescued the NHEJ defect; conversely, suppression of PTEN compromised NHEJ. Mechanistic studies revealed that PTEN promotes NHEJ through direct induction of expression of XRCC4-like factor (NHEJ1/XLF), which functions in DNA end bridging and ligation. PTEN was found to occupy the NHEJ1 gene promoter and to recruit the histone acetyltransferases, PCAF and CBP, inducing XLF expression. This recruitment activity was found to be independent of its phosphatase activity, but dependent on K128, a site of regulatory acetylation on PTEN. These findings define a novel function for PTEN in regulating NHEJ DSB repair, and therefore may assist in the design of individualized strategies for cancer therapy.Implications: PTEN is the second most frequently lost tumor suppressor gene. Here it is demonstrated that PTEN has a direct and novel regulatory role in NHEJ, a key DNA repair pathway in response to radiation and chemotherapy. Mol Cancer Res; 16(8); 1241-54. ©2018 AACR.
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Affiliation(s)
| | - Susan E Scanlon
- Department of Experimental Pathology, Yale University, New Haven, Connecticut
| | - Sebastian Oeck
- Department of Therapeutic Radiology, Yale University, New Haven, Connecticut.,Institute of Cell Biology (Cancer Research), University of Duisburg-Essen, Essen, Germany
| | - Peter M Glazer
- Department of Genetics, Yale University, New Haven, Connecticut. .,Department of Therapeutic Radiology, Yale University, New Haven, Connecticut
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19
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Oing C, Tennstedt P, Simon R, Volquardsen J, Borgmann K, Bokemeyer C, Petersen C, Dikomey E, Rothkamm K, Mansour WY. BCL2-overexpressing prostate cancer cells rely on PARP1-dependent end-joining and are sensitive to combined PARP inhibitor and radiation therapy. Cancer Lett 2018. [PMID: 29526801 DOI: 10.1016/j.canlet.2018.03.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Here we report that BCL2 blocks DNA double strand break (DSB) repair via nonhomologous end-joining (NHEJ), through sequestration of KU80 protein outside the nucleus. We find that this effect is associated with a repair switch to the error-prone PARP1-dependent end-joining (PARP1-EJ). We present in-vitro proof-of-concept for therapeutic targeting of this switch using PARP inhibitor to specifically enhance the radiosensitivity of BCL2-overexpressing cells. Given its erroneous behavior, PARP1-EJ might allow for the accumulation of genetic alterations and tumor progression. Consistently, we report an inverse correlation between BCL2 expression and biochemical recurrence-free survival of 10.259 prostate cancer (PCa) patients who underwent primary radical-prostatectomy for localized disease. Further, we evaluated retrospectively the impact of BCL2 expression on clinical outcome of 1.426 PCa patients, who had been given salvage radiotherapy at relapse after radical prostatectomy. In line with its role in blocking NHEJ, BCL2 over-expressers showed significantly better response to salvage radiotherapy compared to low-expressers. Collectively, our findings identify BCL2 status in PCa as a putative predictor of (i) radiotherapy response and (ii) response to treatment with PARP inhibitor olaparib as a radiosensitizing agent.
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Affiliation(s)
- Christoph Oing
- Laboratory of Radiobiology and Experimental Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Department of Oncology, Hematology and Bone Marrow Transplantation with Section of Pneumology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Pierre Tennstedt
- Martini-Clinic, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Ronald Simon
- Department of Pathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jennifer Volquardsen
- Laboratory of Radiobiology and Experimental Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kerstin Borgmann
- Laboratory of Radiobiology and Experimental Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Carsten Bokemeyer
- Department of Oncology, Hematology and Bone Marrow Transplantation with Section of Pneumology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Cordula Petersen
- Department of Radiotherapy and Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Ekkehard Dikomey
- Laboratory of Radiobiology and Experimental Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kai Rothkamm
- Laboratory of Radiobiology and Experimental Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Wael Y Mansour
- Laboratory of Radiobiology and Experimental Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Department of Tumor Biology, National Cancer Center, Cairo University, Cairo, Egypt.
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20
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Ku DNA End-Binding Activity Promotes Repair Fidelity and Influences End-Processing During Nonhomologous End-Joining in Saccharomyces cerevisiae. Genetics 2018; 209:115-128. [PMID: 29500182 DOI: 10.1534/genetics.117.300672] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 02/25/2018] [Indexed: 12/21/2022] Open
Abstract
The Ku heterodimer acts centrally in nonhomologous end-joining (NHEJ) of DNA double-strand breaks (DSB). Saccharomyces cerevisiae Ku, like mammalian Ku, binds and recruits NHEJ factors to DSB ends. Consequently, NHEJ is virtually absent in yeast Ku null (yku70∆ or yku80∆) strains. Previously, we unexpectedly observed imprecise NHEJ proficiency in a yeast Ku mutant with impaired DNA end-binding (DEB). However, how DEB impairment supported imprecise NHEJ was unknown. Here, we found imprecise NHEJ proficiency to be a feature of a panel of DEB-impaired Ku mutants and that DEB impairment resulted in a deficiency in precise NHEJ. These results suggest that DEB-impaired Ku specifically promotes error-prone NHEJ. Epistasis analysis showed that classical NHEJ factors, as well as novel and previously characterized NHEJ-specific residues of Ku, are required for the distinct error-prone repair in a Ku DEB mutant. However, sequencing of repair junctions revealed that imprecise repair in Ku DEB mutants was almost exclusively characterized by small deletions, in contrast to the majority of insertions that define imprecise repair in wild-type strains. Notably, while sequencing indicated a lack of Pol4-dependent insertions at the site of repair, Pol2 exonuclease activity, which mediates small deletions in NHEJ, contributed to imprecise NHEJ in a Ku DEB mutant. The deletions were smaller than in Ku-independent microhomology-mediated end-joining (MMEJ) and were neither promoted by Mre11 nuclease activity nor Sae2 Thus, the quality of Ku's engagement at the DNA end influences end-processing during NHEJ and DEB impairment unmasks a Ku-dependent error-prone pathway of end-joining distinct from MMEJ.
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21
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Calcium influx-mediated translocation of m-calpain induces Ku80 cleavage and enhances the Ku80-related DNA repair pathway. Oncotarget 2017; 7:30831-44. [PMID: 27121057 PMCID: PMC5058721 DOI: 10.18632/oncotarget.8791] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 04/01/2016] [Indexed: 01/14/2023] Open
Abstract
Proteomic analysis of ionomycin-treated and untreated mammary epithelial MCF10A cells elucidated differences in Ku80 cleavage. Ku80, a subunit of the Ku protein complex, is an initiator of the non-homologous, end-joining (NHEJ), double-strand breaks (DSBs) repair pathway. The nuclear Ku80 was cleaved in a calcium concentration-dependent manner by m-calpain but not by m-calpain. The cleavage of nuclear Ku80 at its α/β domain was validated by Western blotting analysis using flag-tagged expression vectors of truncated versions of Ku80 and a flag antibody and was confirmed in m-calpain knock-down cells and in vitro cell-free evaluation with recombinant proteins of calpains, Ku70, and Ku80. In addition, the cleaved Ku80 still formed a Ku heterodimer and promoted DNA DSB repair activity. Taken together, these findings indicate that translocated m-calpain enhances the NHEJ pathway through the cleavage of Ku80. Based on the present study, m-calpain in DNA repair pathways might be a novel anticancer drug target, or its mechanism might be a possible route for resistance acquisition of DNA damage-inducing chemotherapeutics.
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22
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Graham TGW, Walter JC, Loparo JJ. Ensemble and Single-Molecule Analysis of Non-Homologous End Joining in Frog Egg Extracts. Methods Enzymol 2017. [PMID: 28645371 DOI: 10.1016/bs.mie.2017.03.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Non-homologous end joining (NHEJ) repairs the majority of DNA double-strand breaks in human cells, yet the detailed order of events in this process has remained obscure. Here, we describe how to employ Xenopus laevis egg extract for the study of NHEJ. The egg extract is easy to prepare in large quantities, and it performs efficient end joining that requires the core end joining proteins Ku, DNA-PKcs, XLF, XRCC4, and DNA ligase IV. These factors, along with the rest of the soluble proteome, are present at endogenous concentrations, allowing mechanistic analysis in a system that begins to approximate the complexity of cellular end joining. We describe an ensemble assay that monitors covalent joining of DNA ends and fluorescence assays that detect joining of single pairs of DNA ends. The latter assay discerns at least two discrete intermediates in the bridging of DNA ends.
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Affiliation(s)
| | - Johannes C Walter
- Harvard Medical School, Boston, MA, United States; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, United States.
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23
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Oguro Y, Yamazaki H, Ara S, Shida Y, Ogasawara W, Takagi M, Takaku H. Efficient gene targeting in non-homologous end-joining-deficient Lipomyces starkeyi strains. Curr Genet 2017; 63:751-763. [DOI: 10.1007/s00294-017-0679-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 01/21/2017] [Accepted: 01/24/2017] [Indexed: 10/20/2022]
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24
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Regulation of non-homologous end joining via post-translational modifications of components of the ligation step. Curr Genet 2016; 63:591-605. [PMID: 27915381 DOI: 10.1007/s00294-016-0670-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 11/25/2016] [Accepted: 11/26/2016] [Indexed: 12/29/2022]
Abstract
DNA double-strand breaks are the most serious type of DNA damage and non-homologous end joining (NHEJ) is an important pathway for their repair. In Saccharomyces cerevisiae, three complexes mediate the canonical NHEJ pathway, Ku (Ku70/Ku80), MRX (Mre11/Rad50/Xrs2) and DNA ligase IV (Dnl4/Lif1). Mammalian NHEJ is more complex, primarily as a consequence of the fact that more factors are involved in the process, and also because higher chromatin organization and more complex regulatory networks exist in mammals. In addition, a stronger interconnection between the NHEJ and DNA damage response (DDR) pathways seems to occur in mammals compared to yeast. DDR employs multiple post-translational modifications (PTMs) of the target proteins and mutual crosstalk among them to ensure highly efficient down-stream effects. Checkpoint-mediated phosphorylation is the best understood PTM that regulates DDR, although recently SUMOylation has also been shown to be involved. Both phosphorylation and SUMOylation affect components of NHEJ. In this review, we discuss a role of these two PTMs in regulation of NHEJ via targeting the components of the ligation step.
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Yang K, Guo R, Xu D. Non-homologous end joining: advances and frontiers. Acta Biochim Biophys Sin (Shanghai) 2016; 48:632-40. [PMID: 27217473 DOI: 10.1093/abbs/gmw046] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Accepted: 04/18/2016] [Indexed: 12/21/2022] Open
Abstract
DNA double-strand breaks (DSBs) are the most serious form of DNA damage. In human cells, non-homologous end joining (NHEJ) is the major pathway for the repair of DSBs. Different types of DSBs result in different subsets of NHEJ repair strategies. These variations in NHEJ repair strategies depend on numerous elements, such as the flexible recruitment of NHEJ-related proteins, the complexity of the DSB ends, and the spatial- and temporal-ordered formation of the multi-protein complex. On the one hand, current studies of DNA DSBs repair focus on the repair pathway choices between homologous recombination and classic or alternative NHEJ. On the other hand, increasing researches have also deepened the significance and dug into the cross-links between the NHEJ pathway and the area of genome organization and aging. Although remarkable progress has been made in elucidating the underlying principles during the past decades, the detailed mechanism of action in response to different types of DSBs remains largely unknown and needs further evaluation in the future study.
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Affiliation(s)
- Kai Yang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Rong Guo
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Dongyi Xu
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
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Cytotoxicity and Genotoxicity Assessment of Sandalwood Essential Oil in Human Breast Cell Lines MCF-7 and MCF-10A. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2016; 2016:3696232. [PMID: 27293457 PMCID: PMC4879231 DOI: 10.1155/2016/3696232] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 04/10/2016] [Accepted: 04/19/2016] [Indexed: 11/17/2022]
Abstract
Sandalwood essential oil (SEO) is extracted from Santalum trees. Although α-santalol, a main constituent of SEO, has been studied as a chemopreventive agent, the genotoxic activity of the whole oil in human breast cell lines is still unknown. The main objective of this study was to assess the cytotoxic and genotoxic effects of SEO in breast adenocarcinoma (MCF-7) and nontumorigenic breast epithelial (MCF-10A) cells. Proteins associated with SEO genotoxicity were identified using a proteomics approach. Commercially available, high-purity, GC/MS characterized SEO was used to perform the experiments. The main constituents reported in the oil were (Z)-α-santalol (25.34%), (Z)-nuciferol (18.34%), (E)-β-santalol (10.97%), and (E)-nuciferol (10.46%). Upon exposure to SEO (2-8 μg/mL) for 24 hours, cell proliferation was determined by the MTT assay. Alkaline and neutral comet assays were used to assess genotoxicity. SEO exposure induced single- and double-strand breaks selectively in the DNA of MCF-7 cells. Quantitative LC/MS-based proteomics allowed identification of candidate proteins involved in this response: Ku70 (p = 1.37E - 2), Ku80 (p = 5.8E - 3), EPHX1 (p = 3.3E - 3), and 14-3-3ζ (p = 4.0E - 4). These results provide the first evidence that SEO is genotoxic and capable of inducing DNA single- and double-strand breaks in MCF-7 cells.
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Iuchi K, Yagura T. DNA binding activity of Ku during chemotherapeutic agent-induced early apoptosis. Exp Cell Res 2016; 342:135-44. [PMID: 26976509 DOI: 10.1016/j.yexcr.2016.03.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 03/08/2016] [Accepted: 03/09/2016] [Indexed: 01/09/2023]
Abstract
Ku protein is a heterodimer composed of two subunits, and is capable of both sequence-independent and sequence-specific DNA binding. The former mode of DNA binding plays a crucial role in DNA repair. The biological role of Ku protein during apoptosis remains unclear. Here, we show characterization of Ku protein during apoptosis. In order to study the DNA binding properties of Ku, we used two methods for the electrophoresis mobility shift assay (EMSA). One method, RI-EMSA, which is commonly used, employed radiolabeled DNA probes. The other method, WB-EMSA, employed unlabeled DNA followed by western blot and detection with anti-Ku antiserum. In this study, Ku-DNA probe binding activity was found to dramatically decrease upon etoposide treatment, when examined by the RI-EMSA method. In addition, pre-treatment with apoptotic cell extracts inhibited Ku-DNA probe binding activity in the non-treated cell extract. The inhibitory effect of the apoptotic cell extract was reduced by DNase I treatment. WB-EMSA showed that the Ku in the apoptotic cell extract bound to fragmented endogenous DNA. Interestingly, Ku in the apoptotic cell extract purified by the Resource Q column bound 15-bp DNA in both RI-EMSA and WB-EMSA, whereas Ku in unpurified apoptotic cell extracts did not bind additional DNA. These results suggest that Ku binds cleaved chromosomal DNA and/or nucleosomes in apoptotic cells. In conclusion, Ku is intact and retains DNA binding activity in early apoptotic cells.
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Affiliation(s)
- Katsuya Iuchi
- Department of Bioscience, Faculty of Science and Technology, Kwansei Gakuin University, 2-1 Gakuin, Sanda-shi, Hyogo-ken 669-1337, Japan.
| | - Tatsuo Yagura
- Department of Bioscience, Faculty of Science and Technology, Kwansei Gakuin University, 2-1 Gakuin, Sanda-shi, Hyogo-ken 669-1337, Japan
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Kleinboelting N, Huep G, Appelhagen I, Viehoever P, Li Y, Weisshaar B. The Structural Features of Thousands of T-DNA Insertion Sites Are Consistent with a Double-Strand Break Repair-Based Insertion Mechanism. MOLECULAR PLANT 2015; 8:1651-64. [PMID: 26343971 DOI: 10.1016/j.molp.2015.08.011] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 07/28/2015] [Accepted: 08/13/2015] [Indexed: 05/06/2023]
Abstract
Transformation by Agrobacterium tumefaciens, an important tool in modern plant research, involves the integration of T-DNA initially present on a plasmid in agrobacteria into the genome of plant cells. The process of attachment of the agrobacteria to plant cells and the transport of T-DNA into the cell and further to the nucleus has been well described. However, the exact mechanism of integration into the host's DNA is still unclear, although several models have been proposed. During confirmation of T-DNA insertion alleles from the GABI-Kat collection of Arabidopsis thaliana mutants, we have generated about 34,000 sequences from the junctions between inserted T-DNA and adjacent genome regions. Here, we describe the evaluation of this dataset with regard to existing models for T-DNA integration. The results suggest that integration into the plant genome is mainly mediated by the endogenous plant DNA repair machinery. The observed integration events showed characteristics highly similar to those of repair sites of double-strand breaks with respect to microhomology and deletion sizes. In addition, we describe unexpected integration events, such as large deletions and inversions at the integration site that are relevant for correct interpretation of results from T-DNA insertion mutants in reverse genetics experiments.
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Affiliation(s)
- Nils Kleinboelting
- Center for Biotechnology & Department of Biology, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany
| | - Gunnar Huep
- Center for Biotechnology & Department of Biology, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany
| | - Ingo Appelhagen
- Center for Biotechnology & Department of Biology, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany
| | - Prisca Viehoever
- Center for Biotechnology & Department of Biology, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany
| | - Yong Li
- Department of Medicine IV, University Hospital Freiburg, Berliner Allee 29, 79110 Freiburg, Germany
| | - Bernd Weisshaar
- Center for Biotechnology & Department of Biology, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany.
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Dhivya S, Premkumar K. Nomadic genetic elements contribute to oncogenic translocations: Implications in carcinogenesis. Crit Rev Oncol Hematol 2015; 98:81-93. [PMID: 26548742 DOI: 10.1016/j.critrevonc.2015.10.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 10/05/2015] [Accepted: 10/27/2015] [Indexed: 12/22/2022] Open
Abstract
Chromosomal translocations as molecular signatures have been reported in various malignancies but, the mechanism behind which is largely unknown. Swapping of chromosomal fragments occurs by induction of double strand breaks (DSBs), most of which were initially assumed de novo. However, decoding of human genome proved that transposable elements (TE) might have profound influence on genome integrity. TEs are highly conserved mobile genetic elements that generate DSBs, subsequently resulting in large chromosomal rearrangements. Previously TE insertions were thought to be harmless, but recently gains attention due to the origin of spectrum of post-insertional genomic alterations and subsequent transcriptional alterations leading to development of deleterious effects mainly carcinogenesis. Though the existing knowledge on the cancer-associated TE dynamics is very primitive, exploration of underlying mechanism promises better therapeutic strategies for cancer. Thus, this review focuses on the prevalence of TE in the genome, associated genomic instability upon transposition activation and impact on tumorigenesis.
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Affiliation(s)
- Sridaran Dhivya
- Cancer Genetics and Nanomedicine Laboratory, Department of Biomedical Science, School of Basic Medical Sciences, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India
| | - Kumpati Premkumar
- Cancer Genetics and Nanomedicine Laboratory, Department of Biomedical Science, School of Basic Medical Sciences, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India.
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He MD, Zhang FH, Wang HL, Wang HP, Zhu ZY, Sun YH. Efficient ligase 3-dependent microhomology-mediated end joining repair of DNA double-strand breaks in zebrafish embryos. Mutat Res 2015; 780:86-96. [PMID: 26318124 DOI: 10.1016/j.mrfmmm.2015.08.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 07/21/2015] [Accepted: 08/14/2015] [Indexed: 02/07/2023]
Abstract
DNA double-strand break (DSB) repair is of considerable importance for genomic integrity. Homologous recombination (HR) and non-homologous end joining (NHEJ) are considered as two major mechanistically distinct pathways involved in repairing DSBs. In recent years, another DSB repair pathway, namely, microhomology-mediated end joining (MMEJ), has received increasing attention. MMEJ is generally believed to utilize an alternative mechanism to repair DSBs when NHEJ and other mechanisms fail. In this study, we utilized zebrafish as an in vivo model to study DSB repair and demonstrated that efficient MMEJ repair occurred in the zebrafish genome when DSBs were induced using TALEN (transcription activator-like effector nuclease) or CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 technologies. The wide existence of MMEJ repair events in zebrafish embryos was further demonstrated via the injection of several in vitro-designed exogenous MMEJ reporters. Interestingly, the inhibition of endogenous ligase 4 activity significantly increased MMEJ frequency, and the inhibition of ligase 3 activity severely decreased MMEJ activity. These results suggest that MMEJ in zebrafish is dependent on ligase 3 but independent of ligase 4. This study will enhance our understanding of the mechanisms of MMEJ in vivo and facilitate inducing desirable mutations via DSB-induced repair.
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Affiliation(s)
- Mu-Dan He
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Feng-Hua Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Hua-Lin Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Hou-Peng Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Zuo-Yan Zhu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Yong-Hua Sun
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
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Galli A, Chan CY, Parfenova L, Cervelli T, Schiestl RH. Requirement of POL3 and POL4 on non-homologous and microhomology-mediated end joining in rad50/xrs2 mutants of Saccharomyces cerevisiae. Mutagenesis 2015; 30:841-9. [PMID: 26122113 DOI: 10.1093/mutage/gev046] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Non-homologous end joining (NHEJ) directly joins two broken DNA ends without sequence homology. A distinct pathway called microhomology-mediated end joining (MMEJ) relies on a few base pairs of homology between the recombined DNA. The majority of DNA double-strand breaks caused by endogenous oxygen species or ionizing radiation contain damaged bases that hinder direct religation. End processing is required to remove mismatched nucleotides and fill in gaps during end joining of incompatible ends. POL3 in Saccharomyces cerevisiae encodes polymerase δ that is required for DNA replication and other DNA repair processes. Our previous results have shown that POL3 is involved in gap filling at 3' overhangs in POL4-independent NHEJ. Here, we studied the epistatic interaction between POL3, RAD50, XRS2 and POL4 in NHEJ using a plasmid-based endjoining assay in yeast. We demonstrated that either rad50 or xrs2 mutation is epistatic for end joining of compatible ends in the rad50 pol3-t or xrs2 pol3-t double mutants. However, the pol3-t and rad50 or pol3-t and xrs2 mutants caused an additive decrease in the end-joining efficiency of incompatible ends, suggesting that POL3 and RAD50 or POL3 and XRS2 exhibit independent functions in NHEJ. In the rad50 pol4 mutant, end joining of incompatible ends was not detected. In the rad50 or xrs2 mutants, NHEJ events did not contain any microhomology at the rejoined junctions. The pol3-t mutation restored MMEJ in the rad50 or xrs2 mutant backgrounds. Moreover, we demonstrated that NHEJ of incompatible ends required RAD50 and POL4 more than POL3. In conclusion, POL3 and POL4 have differential functions in NHEJ, independent of the RAD50-mediated repair pathway.
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Affiliation(s)
| | - Cecilia Y Chan
- Departments of Pathology, Environmental Health, and Radiation Oncology, David Geffen School of Medicine at UCLA and UCLA School of Public Health, 71-295 CHS, 650 Charles E. Young Drive South, Los Angeles, CA, USA
| | - Liubov Parfenova
- Departments of Pathology, Environmental Health, and Radiation Oncology, David Geffen School of Medicine at UCLA and UCLA School of Public Health, 71-295 CHS, 650 Charles E. Young Drive South, Los Angeles, CA, USA
| | | | - Robert H Schiestl
- Departments of Pathology, Environmental Health, and Radiation Oncology, David Geffen School of Medicine at UCLA and UCLA School of Public Health, 71-295 CHS, 650 Charles E. Young Drive South, Los Angeles, CA, USA
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Park SY, Vaghchhipawala Z, Vasudevan B, Lee LY, Shen Y, Singer K, Waterworth WM, Zhang ZJ, West CE, Mysore KS, Gelvin SB. Agrobacterium T-DNA integration into the plant genome can occur without the activity of key non-homologous end-joining proteins. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 81:934-46. [PMID: 25641249 DOI: 10.1111/tpj.12779] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 01/19/2015] [Accepted: 01/20/2015] [Indexed: 05/29/2023]
Abstract
Non-homologous end joining (NHEJ) is the major model proposed for Agrobacterium T-DNA integration into the plant genome. In animal cells, several proteins, including KU70, KU80, ARTEMIS, DNA-PKcs, DNA ligase IV (LIG4), Ataxia telangiectasia mutated (ATM), and ATM- and Rad3-related (ATR), play an important role in 'classical' (c)NHEJ. Other proteins, including histone H1 (HON1), XRCC1, and PARP1, participate in a 'backup' (b)NHEJ process. We examined transient and stable transformation frequencies of Arabidopsis thaliana roots mutant for numerous NHEJ and other related genes. Mutants of KU70, KU80, and the plant-specific DNA Ligase VI (LIG6) showed increased stable transformation susceptibility. However, these mutants showed transient transformation susceptibility similar to that of wild-type plants, suggesting enhanced T-DNA integration in these mutants. These results were confirmed using a promoter-trap transformation vector that requires T-DNA integration into the plant genome to activate a promoterless gusA (uidA) gene, by virus-induced gene silencing (VIGS) of Nicotiana benthamiana NHEJ genes, and by biochemical assays for T-DNA integration. No alteration in transient or stable transformation frequencies was detected with atm, atr, lig4, xrcc1, or parp1 mutants. However, mutation of parp1 caused high levels of T-DNA integration and transgene methylation. A double mutant (ku80/parp1), knocking out components of both NHEJ pathways, did not show any decrease in stable transformation or T-DNA integration. Thus, T-DNA integration does not require known NHEJ proteins, suggesting an alternative route for integration.
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Affiliation(s)
- So-Yon Park
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA; Plant Transformation Core Facility, University of Missouri, Columbia, MO, 65211, USA; Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA, 24061, USA
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Badie S, Carlos AR, Folio C, Okamoto K, Bouwman P, Jonkers J, Tarsounas M. BRCA1 and CtIP promote alternative non-homologous end-joining at uncapped telomeres. EMBO J 2015; 34:410-24. [PMID: 25582120 PMCID: PMC4339125 DOI: 10.15252/embj.201488947] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 10/29/2014] [Accepted: 11/25/2014] [Indexed: 12/15/2022] Open
Abstract
Loss of telomere protection occurs during physiological cell senescence and ageing, due to attrition of telomeric repeats and insufficient retention of the telomere-binding factor TRF2. Subsequently formed telomere fusions trigger rampant genomic instability leading to cell death or tumorigenesis. Mechanistically, telomere fusions require either the classical non-homologous end-joining (C-NHEJ) pathway dependent on Ku70/80 and LIG4, or the alternative non-homologous end-joining (A-NHEJ), which relies on PARP1 and LIG3. Here, we show that the tumour suppressor BRCA1, together with its interacting partner CtIP, both acting in end resection, also promotes end-joining of uncapped telomeres. BRCA1 and CtIP do not function in the ATM-dependent telomere damage signalling, nor in telomere overhang removal, which are critical for telomere fusions by C-NHEJ. Instead, BRCA1 and CtIP act in the same pathway as LIG3 to promote joining of de-protected telomeres by A-NHEJ. Our work therefore ascribes novel roles for BRCA1 and CtIP in end-processing and fusion reactions at uncapped telomeres, underlining the complexity of DNA repair pathways that act at chromosome ends lacking protective structures. Moreover, A-NHEJ provides a mechanism of previously unanticipated significance in telomere dysfunction-induced genome instability.
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Affiliation(s)
- Sophie Badie
- Telomere and Genome Stability Group, The CR-UK/MRC Gray Institute for Radiation Oncology and Biology, Oxford, UK
| | - Ana Rita Carlos
- Telomere and Genome Stability Group, The CR-UK/MRC Gray Institute for Radiation Oncology and Biology, Oxford, UK
| | - Cecilia Folio
- Telomere and Genome Stability Group, The CR-UK/MRC Gray Institute for Radiation Oncology and Biology, Oxford, UK
| | - Keiji Okamoto
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Peter Bouwman
- Division of Molecular Pathology and Cancer Systems Biology Centre, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Jos Jonkers
- Division of Molecular Pathology and Cancer Systems Biology Centre, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Madalena Tarsounas
- Telomere and Genome Stability Group, The CR-UK/MRC Gray Institute for Radiation Oncology and Biology, Oxford, UK
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Joshi N, Grant SG. Pulsed-field gel electrophoresis analysis of multicellular DNA double-strand break damage and repair. Methods Mol Biol 2014; 1105:193-202. [PMID: 24623230 DOI: 10.1007/978-1-62703-739-6_16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
This assay quantifies the extent of double-strand break (DSB) DNA damage in cell populations embedded in agarose and analyzed for migratory DNA using pulsed-field gel electrophoresis with ethidium bromide staining. The assay can measure preexisting damage as well as induction of DSB by chemical (e.g., bleomycin), physical (e.g., X-irradiation), or biological (e.g., restriction enzymes) agents. By incubating the cells under physiological conditions prior to processing, the cells can be allowed to repair DSB, primarily via the process of nonhomologous end joining. The amount of repair, corresponding to the repair capacity of the treated cells, is then quantified by determining the ratio of the fractions of activity released in the lanes in comparison to the total amount of DNA fragmentation following determination of an optimal exposure for maximum initial fragmentation. Repair kinetics can also be analyzed through a time-course regimen.
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Affiliation(s)
- Nina Joshi
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
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Abstract
Double-strand breaks (DSB) in genomic DNA are induced by ionizing radiation or radiomimetic drugs but also occur spontaneously during the cell cycle at quite significant frequencies. In vertebrate cells, nonhomologous DNA end joining (NHEJ) is considered the major pathway of DSB repair which is able to rejoin two broken DNA termini directly end-to-end irrespective of sequence and structure. Genetic studies in various radiosensitive and DSB repair-deficient cell lines yielded insight into the factors involved in NHEJ. Studies in cell-free systems derived from Xenopus eggs and mammalian cells allowed the dissection of the underlying mechanisms. In the present chapter, we describe a protocol for the preparation of whole cell extracts from mammalian cells and a plasmid-based in vitro assay which permits the easy analysis of the efficiency and fidelity of DSB repair via NHEJ in different cell types.
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Jones RE, Oh S, Grimstead JW, Zimbric J, Roger L, Heppel NH, Ashelford KE, Liddiard K, Hendrickson EA, Baird DM. Escape from telomere-driven crisis is DNA ligase III dependent. Cell Rep 2014; 8:1063-76. [PMID: 25127141 DOI: 10.1016/j.celrep.2014.07.007] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/28/2014] [Accepted: 07/10/2014] [Indexed: 12/27/2022] Open
Abstract
Short dysfunctional telomeres are capable of fusion, generating dicentric chromosomes and initiating breakage-fusion-bridge cycles. Cells that escape the ensuing cellular crisis exhibit large-scale genomic rearrangements that drive clonal evolution and malignant progression. We demonstrate that there is an absolute requirement for fully functional DNA ligase III (LIG3), but not ligase IV (LIG4), to facilitate the escape from a telomere-driven crisis. LIG3- and LIG4-dependent alternative (A) and classical (C) nonhomologous end-joining (NHEJ) pathways were capable of mediating the fusion of short dysfunctional telomeres, both displaying characteristic patterns of microhomology and deletion. Cells that failed to escape crisis exhibited increased proportions of C-NHEJ-mediated interchromosomal fusions, whereas those that escaped displayed increased proportions of intrachromosomal fusions. We propose that the balance between inter- and intrachromosomal telomere fusions dictates the ability of human cells to escape crisis and is influenced by the relative activities of A- and C-NHEJ at short dysfunctional telomeres.
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Affiliation(s)
- Rhiannon E Jones
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Sehyun Oh
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Julia W Grimstead
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Jacob Zimbric
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Laureline Roger
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Nicole H Heppel
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Kevin E Ashelford
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Kate Liddiard
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Duncan M Baird
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.
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The fidelity of the ligation step determines how ends are resolved during nonhomologous end joining. Nat Commun 2014; 5:4286. [PMID: 24989324 PMCID: PMC4107315 DOI: 10.1038/ncomms5286] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 06/03/2014] [Indexed: 12/21/2022] Open
Abstract
Nonhomologous end joining (NHEJ) can effectively resolve chromosome breaks despite diverse end structures, but it is unclear how the steps employed for resolution are determined. We sought to address this question by analyzing cellular NHEJ of ends with systematically mispaired and damaged termini. We show NHEJ is uniquely proficient at bypassing subtle terminal mispairs and radiomimetic damage by direct ligation. Nevertheless, bypass ability varies widely, with increases in mispair severity gradually reducing bypass products from 85% to 6%. End-processing by nucleases and polymerases is increased to compensate, though paths with the fewest number of steps to generate a substrate suitable for ligation are favored. Thus, both the frequency and nature of end processing are tailored to meet the needs of the ligation step. We propose a model where the ligase organizes all steps during NHEJ within the stable paired-end complex to limit end processing and associated errors.
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Frit P, Barboule N, Yuan Y, Gomez D, Calsou P. Alternative end-joining pathway(s): bricolage at DNA breaks. DNA Repair (Amst) 2014; 17:81-97. [PMID: 24613763 DOI: 10.1016/j.dnarep.2014.02.007] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 02/01/2014] [Accepted: 02/10/2014] [Indexed: 10/25/2022]
Abstract
To cope with DNA double strand break (DSB) genotoxicity, cells have evolved two main repair pathways: homologous recombination which uses homologous DNA sequences as repair templates, and non-homologous Ku-dependent end-joining involving direct sealing of DSB ends by DNA ligase IV (Lig4). During the last two decades a third player most commonly named alternative end-joining (A-EJ) has emerged, which is defined as any Ku- or Lig4-independent end-joining process. A-EJ increasingly appears as a highly error-prone bricolage on DSBs and despite expanding exploration, it still escapes full characterization. In the present review, we discuss the mechanism and regulation of A-EJ as well as its biological relevance under physiological and pathological situations, with a particular emphasis on chromosomal instability and cancer. Whether or not it is a genuine DSB repair pathway, A-EJ is emerging as an important cellular process and understanding A-EJ will certainly be a major challenge for the coming years.
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Affiliation(s)
- Philippe Frit
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, 31077 Toulouse, Cedex4, France; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France; Equipe labellisée Ligue Nationale Contre le Cancer, France
| | - Nadia Barboule
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, 31077 Toulouse, Cedex4, France; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France; Equipe labellisée Ligue Nationale Contre le Cancer, France
| | - Ying Yuan
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, 31077 Toulouse, Cedex4, France; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France; Equipe labellisée Ligue Nationale Contre le Cancer, France
| | - Dennis Gomez
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, 31077 Toulouse, Cedex4, France; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France; Equipe labellisée Ligue Nationale Contre le Cancer, France
| | - Patrick Calsou
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, 31077 Toulouse, Cedex4, France; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France; Equipe labellisée Ligue Nationale Contre le Cancer, France.
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Targeting components of the alternative NHEJ pathway sensitizes KRAS mutant leukemic cells to chemotherapy. Blood 2014; 123:2355-66. [PMID: 24505083 DOI: 10.1182/blood-2013-01-477620] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Activating KRAS mutations are detected in a substantial number of hematologic malignancies. In a murine T-cell acute lymphoblastic leukemia (T-ALL) model, we previously showed that expression of oncogenic Kras induced a premalignant state accompanied with an arrest in T-cell differentiation and acquisition of somatic Notch1 mutations. These findings prompted us to investigate whether the expression of oncogenic KRAS directly affects DNA damage repair. Applying divergent, but complementary, genetic approaches, we demonstrate that the expression of KRAS mutants is associated with increased expression of DNA ligase 3α, poly(ADP-ribose) polymerase 1 (PARP1), and X-ray repair cross-complementing protein 1 (XRCC1), all essential components of the error-prone, alternative nonhomologous end-joining (alt-NHEJ) pathway. Functional studies revealed delayed repair kinetics, increased misrepair of DNA double-strand breaks, and the preferential use of microhomologous DNA sequences for end joining. Similar effects were observed in primary murine T-ALL blasts. We further show that KRAS-mutated cells, but not KRAS wild-type cells, rely on the alt-NHEJ repair pathway on genotoxic stress. RNA interference-mediated knockdown of DNA ligase 3α abolished resistance to apoptotic cell death in KRAS-mutated cells. Our data indicate that targeting components of the alt-NHEJ pathway sensitizes KRAS-mutated leukemic cells to standard chemotherapeutics and represents a promising approach for inducing synthetic lethal vulnerability in cells harboring otherwise nondruggable KRAS mutations.
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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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Poschmann G, Lendzian A, Uszkoreit J, Eisenacher M, Borght AV, Ramaekers FC, Meyer HE, Stühler K. A combination of two electrophoretical approaches for detailed proteome-based characterization of SCLC subtypes. Arch Physiol Biochem 2013; 119:114-25. [PMID: 23651173 DOI: 10.3109/13813455.2013.789529] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONTEXT Small cell lung cancers (SCLC) are heterogeneous and tumours differ in growth characteristics and treatment resistance. OBJECTIVE To get insight into the underlying protein profiles responsible for this heterogeneity, two subtypes of SCLC cells mutually differing in chemo resistance properties and growth characteristics are analysed. MATERIALS AND METHODS Two different electrophoresis approaches in combination with mass spectrometry were used to detect differences between the SCLC cell lines GLC1 and GLC1M13: IEF/SDS-PAGE as well as cetyltrimethylammonium bromide (CTAB)-SDS-PAGE. RESULTS Altogether 60 non redundant differentially expressed proteins were found of which 5 were verified by Western Blot analysis. DISCUSSION Most of these proteins identified are involved in processes of tumour progression. Therefore, these proteins are interesting candidates for further functional analysis. CONCLUSION Additional CTAB-SDS page is a complementary method to IEF-SDS page revealing a complete new subset of proteins differentially expressed between GLC1 and GLC1 M13 cells SCLC subtypes.
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MESH Headings
- Blotting, Western
- Cell Line, Tumor
- Cetrimonium
- Cetrimonium Compounds/chemistry
- Drug Resistance, Neoplasm
- Electrophoresis, Gel, Two-Dimensional/methods
- Electrophoresis, Polyacrylamide Gel/methods
- Gene Expression Profiling
- Gene Expression Regulation, Neoplastic
- Humans
- Image Processing, Computer-Assisted
- Isoelectric Focusing
- Lung Neoplasms/chemistry
- Lung Neoplasms/diagnosis
- Lung Neoplasms/genetics
- Lung Neoplasms/pathology
- Molecular Sequence Annotation
- Neoplasm Proteins/analysis
- Neoplasm Proteins/genetics
- Proteomics
- Small Cell Lung Carcinoma/chemistry
- Small Cell Lung Carcinoma/diagnosis
- Small Cell Lung Carcinoma/genetics
- Small Cell Lung Carcinoma/pathology
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
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Affiliation(s)
- Gereon Poschmann
- Molecular Proteomics Laboratory, BMFZ, Universität Düsseldorf, Germany.
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42
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Jia Q, den Dulk-Ras A, Shen H, Hooykaas PJJ, de Pater S. Poly(ADP-ribose)polymerases are involved in microhomology mediated back-up non-homologous end joining in Arabidopsis thaliana. PLANT MOLECULAR BIOLOGY 2013; 82:339-51. [PMID: 23625359 DOI: 10.1007/s11103-013-0065-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 04/20/2013] [Indexed: 05/25/2023]
Abstract
Besides the KU-dependent classical non-homologous end-joining (C-NHEJ) pathway, an alternative NHEJ pathway first identified in mammalian systems, which is often called the back-up NHEJ (B-NHEJ) pathway, was also found in plants. In mammalian systems PARP was found to be one of the essential components in B-NHEJ. Here we investigated whether PARP1 and PARP2 were also involved in B-NHEJ in Arabidopsis. To this end Arabidopsis parp1, parp2 and parp1parp2 (p1p2) mutants were isolated and functionally characterized. The p1p2 double mutant was crossed with the C-NHEJ ku80 mutant resulting in the parp1parp2ku80 (p1p2k80) triple mutant. As expected, because of their role in single strand break repair (SSBR) and base excision repair (BER), the p1p2 and p1p2k80 mutants were shown to be sensitive to treatment with the DNA damaging agent MMS. End-joining assays in cell-free leaf protein extracts of the different mutants using linear DNA substrates with different ends reflecting a variety of double strand breaks were performed. The results showed that compatible 5'-overhangs were accurately joined in all mutants, that KU80 protected the ends preventing the formation of large deletions and that PARP proteins were involved in microhomology mediated end joining (MMEJ), one of the characteristics of B-NHEJ.
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Affiliation(s)
- Qi Jia
- Department of Molecular and Developmental Genetics, Institute of Biology, Leiden University, Leiden, The Netherlands
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43
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Abdelbaqi K, Di Paola D, Rampakakis E, Zannis-Hadjopoulos M. Ku protein levels, localization and association to replication origins in different stages of breast tumor progression. J Cancer 2013; 4:358-70. [PMID: 23781282 PMCID: PMC3677623 DOI: 10.7150/jca.6289] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 05/23/2013] [Indexed: 11/05/2022] Open
Abstract
Human origins of DNA replication are specific sequences within the genome whereby DNA replication is initiated. A select group of proteins, known as the pre-replication (pre-RC) complex, in whose formation the Ku protein (Ku70/Ku86) was shown to play a role, bind to replication origins to initiate DNA replication. In this study, we have examined the involvement of Ku in breast tumorigenesis and tumor progression and found that the Ku protein expression levels in human breast metastatic (MCF10AC1a) cells were higher in the chromatin fraction compared to hyperplastic (MCF10AT) and normal (MCF10A) human breast cells, but remained constant in both the nuclear and cytoplasmic fractions. In contrast, in human intestinal cells, the Ku expression level was relatively constant for all cell fractions. Nascent DNA abundance and chromatin association of Ku70/86 revealed that the c-myc origin activity in MCF10AC1a is 2.5 to 5-fold higher than in MCF10AT and MCF10A, respectively, and Ku was bound to the c-myc origin more abundantly in MCF10AC1a, by approximately 1.5 to 4.2-fold higher than in MCF10AT and MCF10A, respectively. In contrast, similar nascent DNA abundance and chromatin association was found for all cell lines for the lamin B2 origin, associated with the constitutively active housekeeping lamin B2 gene. Electrophoretic mobility shift assays (EMSAs) performed on the nuclear extracts (NEs) of the three cell types revealed the presence of protein-DNA replication complexes on both the c-myc and lamin B2 origins, but an increase in binding activity was observed from normal, to transformed, to cancer cells for the c-myc origin, whereas no such difference was seen for the lamin B2 origin. Overall, the results suggest that increased Ku chromatin association, beyond wild type levels, alters cellular processes, which have been implicated in tumorigenesis.
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Affiliation(s)
- Khalil Abdelbaqi
- 1. Goodman Cancer Research Center, McGill University, Montreal, Quebec, Canada H3G 1Y6; ; 2. Department of Biochemistry, McGill University, Montreal, Quebec, Canada H3G 1Y6
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Arslan Z, Wurm R, Brener O, Ellinger P, Nagel-Steger L, Oesterhelt F, Schmitt L, Willbold D, Wagner R, Gohlke H, Smits SHJ, Pul U. Double-strand DNA end-binding and sliding of the toroidal CRISPR-associated protein Csn2. Nucleic Acids Res 2013; 41:6347-59. [PMID: 23625968 PMCID: PMC3695520 DOI: 10.1093/nar/gkt315] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The adaptive immunity of bacteria against foreign nucleic acids, mediated by CRISPR (clustered regularly interspaced short palindromic repeats), relies on the specific incorporation of short pieces of the invading foreign DNA into a special genomic locus, termed CRISPR array. The stored sequences (spacers) are subsequently used in the form of small RNAs (crRNAs) to interfere with the target nucleic acid. We explored the DNA-binding mechanism of the immunization protein Csn2 from the human pathogen Streptococcus agalactiae using different biochemical techniques, atomic force microscopic imaging and molecular dynamics simulations. The results demonstrate that the ring-shaped Csn2 tetramer binds DNA ends through its central hole and slides inward, likely by a screw motion along the helical path of the enclosed DNA. The presented data indicate an accessory function of Csn2 during integration of exogenous DNA by end-joining.
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Affiliation(s)
- Zihni Arslan
- Institut für Physikalische Biologie, Heinrich-Heine-Universität, Universitätsstr. 1, 40225 Düsseldorf, Germany
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Decottignies A. Alternative end-joining mechanisms: a historical perspective. Front Genet 2013; 4:48. [PMID: 23565119 PMCID: PMC3613618 DOI: 10.3389/fgene.2013.00048] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 03/15/2013] [Indexed: 12/29/2022] Open
Abstract
In the presence of functional DNA repair pathways, DNA double-strand breaks (DSBs) are mainly repaired by non-homologous end-joining (NHEJ) or homologous recombination (HR), two conserved pathways that protect cells from aberrant chromosomal rearrangements. During the past two decades however, unusual and presumably distinct DNA end-joining repair activities have been unraveled in NHEJ-deficient cells and these are likely to operate in various chromosomal contexts and species. Most alternative DNA end-joining events reported so far appear to involve microhomologous sequences and are likely to rely on a subset of HR enzymes, namely those responsible for the single-strand annealing mechanism of HR, and on DNA Ligase III. Usually, microhomologies are not initially present at DSB ends and thus need to be unmasked through DNA end resection, a process that can lead to extensive nucleotide loss and is therefore highly mutagenic. In addition to microhomology-mediated end-joining events, recent studies in mammalian cells point toward the existence of a distinct and still ill defined alternative end-joining pathway that does not appear to rely on pre-existing microhomologies and may possibly involve DNA Ligase I. Whether dependent on microhomologies or not, alternative DNA end-joining mechanisms are likely to be highly mutagenic in vivo, being able to drive telomere fusion events and cancer-associated chromosomal translocations in mouse models. In the future, it will be important to better characterize the genetic requirements of these mutagenic alternative mechanisms of DNA end-joining.
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Affiliation(s)
- Anabelle Decottignies
- Genetic and Epigenetic Alterations of Genomes, de Duve Institute, Faculty of Pharmacy and Biomedical Sciences, Catholic University of Louvain Brussels, Belgium
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Weingeist DM, Ge J, Wood DK, Mutamba JT, Huang Q, Rowland EA, Yaffe MB, Floyd S, Engelward BP. Single-cell microarray enables high-throughput evaluation of DNA double-strand breaks and DNA repair inhibitors. Cell Cycle 2013; 12:907-15. [PMID: 23422001 DOI: 10.4161/cc.23880] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
A key modality of non-surgical cancer management is DNA damaging therapy that causes DNA double-strand breaks that are preferentially toxic to rapidly dividing cancer cells. Double-strand break repair capacity is recognized as an important mechanism in drug resistance and is therefore a potential target for adjuvant chemotherapy. Additionally, spontaneous and environmentally induced DSBs are known to promote cancer, making DSB evaluation important as a tool in epidemiology, clinical evaluation and in the development of novel pharmaceuticals. Currently available assays to detect double-strand breaks are limited in throughput and specificity and offer minimal information concerning the kinetics of repair. Here, we present the CometChip, a 96-well platform that enables assessment of double-strand break levels and repair capacity of multiple cell types and conditions in parallel and integrates with standard high-throughput screening and analysis technologies. We demonstrate the ability to detect multiple genetic deficiencies in double-strand break repair and evaluate a set of clinically relevant chemical inhibitors of one of the major double-strand break repair pathways, non-homologous end-joining. While other high-throughput repair assays measure residual damage or indirect markers of damage, the CometChip detects physical double-strand breaks, providing direct measurement of damage induction and repair capacity, which may be useful in developing and implementing treatment strategies with reduced side effects.
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Affiliation(s)
- David M Weingeist
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
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47
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The role of insulin-like growth factor binding protein-3 in the breast cancer cell response to DNA-damaging agents. Oncogene 2012. [DOI: 10.1038/onc.2012.538] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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48
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Deletion of the Pichia pastoris KU70 homologue facilitates platform strain generation for gene expression and synthetic biology. PLoS One 2012; 7:e39720. [PMID: 22768112 PMCID: PMC3387205 DOI: 10.1371/journal.pone.0039720] [Citation(s) in RCA: 183] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 05/25/2012] [Indexed: 12/16/2022] Open
Abstract
Targeted gene replacement to generate knock-outs and knock-ins is a commonly used method to study the function of unknown genes. In the methylotrophic yeast Pichia pastoris, the importance of specific gene targeting has increased since the genome sequencing projects of the most commonly used strains have been accomplished, but rapid progress in the field has been impeded by inefficient mechanisms for accurate integration. To improve gene targeting efficiency in P. pastoris, we identified and deleted the P. pastoris KU70 homologue. We observed a substantial increase in the targeting efficiency using the two commonly known and used integration loci HIS4 and ADE1, reaching over 90% targeting efficiencies with only 250-bp flanking homologous DNA. Although the ku70 deletion strain was noted to be more sensitive to UV rays than the corresponding wild-type strain, no lethality, severe growth retardation or loss of gene copy numbers could be detected during repetitive rounds of cultivation and induction of heterologous protein production. Furthermore, we demonstrated the use of the ku70 deletion strain for fast and simple screening of genes in the search of new auxotrophic markers by targeting dihydroxyacetone synthase and glycerol kinase genes. Precise knock-out strains for the well-known P. pastoris AOX1, ARG4 and HIS4 genes and a whole series of expression vectors were generated based on the wild-type platform strain, providing a broad spectrum of precise tools for both intracellular and secreted production of heterologous proteins utilizing various selection markers and integration strategies for targeted or random integration of single and multiple genes. The simplicity of targeted integration in the ku70 deletion strain will further support protein production strain generation and synthetic biology using P. pastoris strains as platform hosts.
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Bolanos-Garcia VM, Wu Q, Ochi T, Chirgadze DY, Sibanda BL, Blundell TL. Spatial and temporal organization of multi-protein assemblies: achieving sensitive control in information-rich cell-regulatory systems. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2012; 370:3023-3039. [PMID: 22615474 DOI: 10.1098/rsta.2011.0268] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The regulation of cellular processes in living organisms requires signalling systems that have a high signal-to-noise ratio. This is usually achieved by transient, multi-protein complexes that assemble cooperatively. Even in the crowded environment of the cell, such assemblies are unlikely to form by chance, thereby providing a sensitive regulation of cellular processes. Furthermore, selectivity and sensitivity may be achieved by the requirement for concerted folding and binding of previously unfolded components. We illustrate these features by focusing on two essential signalling pathways of eukaryotic cells: first, the monitoring and repair of DNA damage by non-homologous end joining, and second, the mitotic spindle assembly checkpoint, which detects and corrects defective attachments of chromosomes to the kinetochore. We show that multi-protein assemblies moderate the full range of functional complexity and diversity in the two signalling systems. Deciphering the nature of the interactions is central to understanding the mechanisms that control the flow of information in cell signalling and regulation.
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Affiliation(s)
- Victor M Bolanos-Garcia
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK.
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50
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Andrin C, McDonald D, Attwood KM, Rodrigue A, Ghosh S, Mirzayans R, Masson JY, Dellaire G, Hendzel MJ. A requirement for polymerized actin in DNA double-strand break repair. Nucleus 2012; 3:384-95. [PMID: 22688650 DOI: 10.4161/nucl.21055] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Nuclear actin is involved in several nuclear processes from chromatin remodeling to transcription. Here we examined the requirement for actin polymerization in DNA double-strand break repair. Double-strand breaks are considered the most dangerous type of DNA lesion. Double-strand break repair consists of a complex set of events that are tightly regulated. Failure at any step can have catastrophic consequences such as genomic instability, oncogenesis or cell death. Many proteins involved in this repair process have been identified and their roles characterized. We discovered that some DNA double-strand break repair factors are capable of associating with polymeric actin in vitro and specifically, that purified Ku70/80 interacts with polymerized actin under these conditions. We find that the disruption of polymeric actin inhibits DNA double strand break repair both in vitro and in vivo. Introduction of nuclear targeted mutant actin that cannot polymerize, or the depolymerization of endogenous actin filaments by the addition of cytochalasin D, alters the retention of Ku80 at sites of DNA damage in live cells. Our results suggest that polymeric actin is required for proper DNA double-strand break repair and may function through the stabilization of the Ku heterodimer at the DNA damage site.
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Affiliation(s)
- Christi Andrin
- Department of Oncology, University of Alberta, Edmonton, AB Canada
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