51
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Goff NJ, Brenière M, Buehl CJ, de Melo AJ, Huskova H, Ochi T, Blundell TL, Mao W, Yu K, Modesti M, Meek K. Catalytically inactive DNA ligase IV promotes DNA repair in living cells. Nucleic Acids Res 2022; 50:11058-11071. [PMID: 36263813 PMCID: PMC9638927 DOI: 10.1093/nar/gkac913] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 10/18/2022] [Indexed: 11/17/2022] Open
Abstract
DNA double strand breaks (DSBs) are induced by external genotoxic agents (ionizing radiation or genotoxins) or by internal processes (recombination intermediates in lymphocytes or by replication errors). The DNA ends induced by these genotoxic processes are often not ligatable, requiring potentially mutagenic end-processing to render ends compatible for ligation by non-homologous end-joining (NHEJ). Using single molecule approaches, Loparo et al. propose that NHEJ fidelity can be maintained by restricting end-processing to a ligation competent short-range NHEJ complex that 'maximizes the fidelity of DNA repair'. These in vitro studies show that although this short-range NHEJ complex requires DNA ligase IV (Lig4), its catalytic activity is dispensable. Here using cellular models, we show that inactive Lig4 robustly promotes DNA repair in living cells. Compared to repair products from wild-type cells, those isolated from cells with inactive Lig4 show a somewhat increased fraction that utilize micro-homology (MH) at the joining site consistent with alternative end-joining (a-EJ). But unlike a-EJ in the absence of NHEJ, a large percentage of joints isolated from cells with inactive Lig4 occur with no MH - thus, clearly distinct from a-EJ. Finally, biochemical assays demonstrate that the inactive Lig4 complex promotes the activity of DNA ligase III (Lig3).
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Affiliation(s)
- Noah J Goff
- College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA,Department of Microbiology & Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA,Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Manon Brenière
- Centre de Recherche en Cancérologie de Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Universiteé, Marseille, France
| | - Christopher J Buehl
- College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA,Department of Microbiology & Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA,Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Abinadabe J de Melo
- Centre de Recherche en Cancérologie de Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Universiteé, Marseille, France
| | - Hana Huskova
- Centre de Recherche en Cancérologie de Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Universiteé, Marseille, France
| | - Takashi Ochi
- The Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9TJ, UK
| | - Tom L Blundell
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Weifeng Mao
- College of Human Medicine, Michigan State University, East Lansing, MI 48824, USA,Department of Microbiology & Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | - Kefei Yu
- College of Human Medicine, Michigan State University, East Lansing, MI 48824, USA,Department of Microbiology & Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | - Mauro Modesti
- Correspondence may also be addressed to Mauro Modesti.
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52
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Cisneros-Aguirre M, Ping X, Stark JM. To indel or not to indel: Factors influencing mutagenesis during chromosomal break end joining. DNA Repair (Amst) 2022; 118:103380. [PMID: 35926296 PMCID: PMC10105512 DOI: 10.1016/j.dnarep.2022.103380] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Revised: 07/22/2022] [Accepted: 07/24/2022] [Indexed: 12/16/2022]
Abstract
Chromosomal DNA double-strand breaks (DSBs) are the effective lesion of radiotherapy and other clastogenic cancer therapeutics, and are also the initiating event of many approaches to gene editing. Ligation of the DSBs by end joining (EJ) pathways can restore the broken chromosome, but the repair junctions can have insertion/deletion (indel) mutations. The indel patterns resulting from DSB EJ are likely defined by the initial structure of the DNA ends, how the ends are processed and synapsed prior to ligation, and the factors that mediate the ligation step. In this review, we describe key factors that influence these steps of DSB EJ in mammalian cells, which is significant both for understanding mutagenesis resulting from clastogenic cancer therapeutics, and for developing approaches to manipulating gene editing outcomes.
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Affiliation(s)
- Metztli Cisneros-Aguirre
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA; Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
| | - Xiaoli Ping
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
| | - Jeremy M Stark
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA; Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA.
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53
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A novel KU70-mutant human leukemic cell line generated using CRISPR-Cas9 shows increased sensitivity to DSB inducing agents and reduced NHEJ activity. Biochim Biophys Acta Gen Subj 2022; 1866:130246. [PMID: 36162731 DOI: 10.1016/j.bbagen.2022.130246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 09/10/2022] [Accepted: 09/19/2022] [Indexed: 11/21/2022]
Abstract
KU70 (XRCC6 gene in humans) is one of the proteins in the KU70-KU80 heterodimer which is the first component recruited to broken DNA ends during DNA double-strand break repair through nonhomologous end joining (NHEJ). Previous studies have shown that Ku70 deficient mouse cells are defective in NHEJ and V(D)J recombination. In contrast, heterozygous KU70 mutant human cell lines did not show any significant change in cell viability and sensitivity towards ionizing radiation. In this study, we used CRISPR-Cas9 technique to generate a KU70 mutant (heterozygous) human pre-B leukemic cell line (N6-KU70-2-DG). We observed that the N6-KU70-2-DG cells showed a prominent reduction in the expression of both KU70 mRNA and protein. The mutant cells showed reduced cell viability, increased sensitivity to DSB inducing agents such as ionizing radiation (IR) and etoposide, and increased number of unrepaired DSBs after exposure to IR. In addition, the mutant cells showed a reduction in the NHEJ activity and increased rate of microhomology mediated joining (MMEJ) activity. KU70 mutant cells also revealed enhanced level of senescence markers following irradiation. Thus, we report a novel KU70-mutant leukemic cell line (heterozygous) with reduced NHEJ, which is sensitive to DNA damaging agents, unlike the previously reported other KU heterozygous mutant cell lines.
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54
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Graham TGW, Ferrie JJ, Dailey GM, Tjian R, Darzacq X. Detecting molecular interactions in live-cell single-molecule imaging with proximity-assisted photoactivation (PAPA). eLife 2022; 11:e76870. [PMID: 35976226 PMCID: PMC9531946 DOI: 10.7554/elife.76870] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 08/16/2022] [Indexed: 11/13/2022] Open
Abstract
Single-molecule imaging provides a powerful way to study biochemical processes in live cells, yet it remains challenging to track single molecules while simultaneously detecting their interactions. Here, we describe a novel property of rhodamine dyes, proximity-assisted photoactivation (PAPA), in which one fluorophore (the 'sender') can reactivate a second fluorophore (the 'receiver') from a dark state. PAPA requires proximity between the two fluorophores, yet it operates at a longer average intermolecular distance than Förster resonance energy transfer (FRET). We show that PAPA can be used in live cells both to detect protein-protein interactions and to highlight a subpopulation of labeled protein complexes in which two different labels are in proximity. In proof-of-concept experiments, PAPA detected the expected correlation between androgen receptor self-association and chromatin binding at the single-cell level. These results establish a new way in which a photophysical property of fluorophores can be harnessed to study molecular interactions in single-molecule imaging of live cells.
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Affiliation(s)
- Thomas GW Graham
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - John Joseph Ferrie
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Gina M Dailey
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Robert Tjian
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
| | - Xavier Darzacq
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
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55
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Cisneros-Aguirre M, Lopezcolorado FW, Tsai LJ, Bhargava R, Stark JM. The importance of DNAPKcs for blunt DNA end joining is magnified when XLF is weakened. Nat Commun 2022; 13:3662. [PMID: 35760797 PMCID: PMC9237100 DOI: 10.1038/s41467-022-31365-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 06/10/2022] [Indexed: 12/13/2022] Open
Abstract
Canonical non-homologous end joining (C-NHEJ) factors can assemble into a long-range (LR) complex with DNA ends relatively far apart that contains DNAPKcs, XLF, XRCC4, LIG4, and the KU heterodimer and a short-range (SR) complex lacking DNAPKcs that has the ends positioned for ligation. Since the SR complex can form de novo, the role of the LR complex (i.e., DNAPKcs) for chromosomal EJ is unclear. We have examined EJ of chromosomal blunt DNA double-strand breaks (DSBs), and found that DNAPKcs is significantly less important than XLF for such EJ. However, weakening XLF via disrupting interaction interfaces causes a marked requirement for DNAPKcs, its kinase activity, and its ABCDE-cluster autophosphorylation sites for blunt DSB EJ. In contrast, other aspects of genome maintenance are sensitive to DNAPKcs kinase inhibition in a manner that is not further enhanced by XLF loss (i.e., suppression of homology-directed repair and structural variants, and IR-resistance). We suggest that DNAPKcs is required to position a weakened XLF in an LR complex that can transition into a functional SR complex for blunt DSB EJ, but also has distinct functions for other aspects of genome maintenance. DNAPKcs and its kinase activity are required for blunt DNA break end joining when the bridging factor XLF is weakened, but for homologous recombination and radiation resistance, the influence of DNAPKcs is not further enhanced with loss of XLF.
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Affiliation(s)
- Metztli Cisneros-Aguirre
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, 1500 E Duarte Rd, Duarte, CA 91010, USA.,Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, 1500 E Duarte Rd, Duarte, CA 91010, USA
| | - Felicia Wednesday Lopezcolorado
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, 1500 E Duarte Rd, Duarte, CA 91010, USA
| | - Linda Jillianne Tsai
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, 1500 E Duarte Rd, Duarte, CA 91010, USA.,Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, 1500 E Duarte Rd, Duarte, CA 91010, USA
| | - Ragini Bhargava
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, 1500 E Duarte Rd, Duarte, CA 91010, USA.,Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, 1500 E Duarte Rd, Duarte, CA 91010, USA.,Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jeremy M Stark
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, 1500 E Duarte Rd, Duarte, CA 91010, USA. .,Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, 1500 E Duarte Rd, Duarte, CA 91010, USA.
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56
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Lu H, Guan J, Wang SY, Li GM, Bohr VA, Davis AJ. DNA-PKcs-dependent phosphorylation of RECQL4 promotes NHEJ by stabilizing the NHEJ machinery at DNA double-strand breaks. Nucleic Acids Res 2022; 50:5635-5651. [PMID: 35580045 PMCID: PMC9178012 DOI: 10.1093/nar/gkac375] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 04/25/2022] [Accepted: 05/03/2022] [Indexed: 12/21/2022] Open
Abstract
Non-homologous end joining (NHEJ) is the major pathway that mediates the repair of DNA double-strand breaks (DSBs) generated by ionizing radiation (IR). Previously, the DNA helicase RECQL4 was implicated in promoting NHEJ, but its role in the pathway remains unresolved. In this study, we report that RECQL4 stabilizes the NHEJ machinery at DSBs to promote repair. Specifically, we find that RECQL4 interacts with the NHEJ core factor DNA-PKcs and the interaction is increased following IR. RECQL4 promotes DNA end bridging mediated by DNA-PKcs and Ku70/80 in vitro and the accumulation/retention of NHEJ factors at DSBs in vivo. Moreover, interaction between DNA-PKcs and the other core NHEJ proteins following IR treatment is attenuated in the absence of RECQL4. These data indicate that RECQL4 promotes the stabilization of the NHEJ factors at DSBs to support formation of the NHEJ long-range synaptic complex. In addition, we observed that the kinase activity of DNA-PKcs is required for accumulation of RECQL4 to DSBs and that DNA-PKcs phosphorylates RECQL4 at six serine/threonine residues. Blocking phosphorylation at these sites reduced the recruitment of RECQL4 to DSBs, attenuated the interaction between RECQL4 and NHEJ factors, destabilized interactions between the NHEJ machinery, and resulted in decreased NHEJ. Collectively, these data illustrate reciprocal regulation between RECQL4 and DNA-PKcs in NHEJ.
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Affiliation(s)
- Huiming Lu
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Junhong Guan
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Shih-Ya Wang
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Guo-Min Li
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Vilhelm A Bohr
- DNA Repair Section, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Anthony J Davis
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
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57
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Cabello-Lobato MJ, Jenner M, Cisneros-Aguirre M, Brüninghoff K, Sandy Z, da Costa I, Jowitt T, Loch C, Jackson S, Wu Q, Mootz H, Stark J, Cliff M, Schmidt C. Microarray screening reveals two non-conventional SUMO-binding modules linked to DNA repair by non-homologous end-joining. Nucleic Acids Res 2022; 50:4732-4754. [PMID: 35420136 PMCID: PMC9071424 DOI: 10.1093/nar/gkac237] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 03/03/2022] [Accepted: 03/25/2022] [Indexed: 11/25/2022] Open
Abstract
SUMOylation is critical for numerous cellular signalling pathways, including the maintenance of genome integrity via the repair of DNA double-strand breaks (DSBs). If misrepaired, DSBs can lead to cancer, neurodegeneration, immunodeficiency and premature ageing. Using systematic human proteome microarray screening combined with widely applicable carbene footprinting, genetic code expansion and high-resolution structural profiling, we define two non-conventional and topology-selective SUMO2-binding regions on XRCC4, a DNA repair protein important for DSB repair by non-homologous end-joining (NHEJ). Mechanistically, the interaction of SUMO2 and XRCC4 is incompatible with XRCC4 binding to three other proteins important for NHEJ-mediated DSB repair. These findings are consistent with SUMO2 forming a redundant NHEJ layer with the potential to regulate different NHEJ complexes at distinct levels including, but not limited to, XRCC4 interactions with XLF, LIG4 and IFFO1. Regulation of NHEJ is not only relevant for carcinogenesis, but also for the design of precision anti-cancer medicines and the optimisation of CRISPR/Cas9-based gene editing. In addition to providing molecular insights into NHEJ, this work uncovers a conserved SUMO-binding module and provides a rich resource on direct SUMO binders exploitable towards uncovering SUMOylation pathways in a wide array of cellular processes.
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Affiliation(s)
- Maria Jose Cabello-Lobato
- Manchester Cancer Research Centre (MCRC), Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, 555 Wilmslow Road, Manchester M20 4GJ, UK
| | - Matthew Jenner
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
- Warwick Integrative Synthetic Biology (WISB) Centre, University of Warwick, Coventry CV4 7AL, UK
| | - Metztli Cisneros-Aguirre
- Department of Cancer Genetics and Epigenetics, Irell and Manella Graduate School of Biological Sciences Beckman Research Institute of the City of Hope, 1500 E Duarte Rd, Duarte, CA 91010, USA
| | - Kira Brüninghoff
- Institute of Biochemistry, University of Muenster, Corrensstraße 36, 48149 Muenster, Germany
| | - Zac Sandy
- Manchester Cancer Research Centre (MCRC), Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, 555 Wilmslow Road, Manchester M20 4GJ, UK
| | - Isabelle C da Costa
- Manchester Cancer Research Centre (MCRC), Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, 555 Wilmslow Road, Manchester M20 4GJ, UK
| | - Thomas A Jowitt
- Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | | | - Stephen P Jackson
- Wellcome/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge, Cambridge CB2 1QN, UK
| | - Qian Wu
- Astbury Centre for Structural Molecular Biology, School of Molecular & Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Henning D Mootz
- Institute of Biochemistry, University of Muenster, Corrensstraße 36, 48149 Muenster, Germany
| | - Jeremy M Stark
- Department of Cancer Genetics and Epigenetics, Irell and Manella Graduate School of Biological Sciences Beckman Research Institute of the City of Hope, 1500 E Duarte Rd, Duarte, CA 91010, USA
| | - Matthew J Cliff
- Manchester Institute of Biotechnology (MIB) and School of Chemistry, University of Manchester, Manchester M1 7DN, UK
| | - Christine K Schmidt
- Manchester Cancer Research Centre (MCRC), Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, 555 Wilmslow Road, Manchester M20 4GJ, UK
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58
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Schaub JM, Soniat MM, Finkelstein IJ. Polymerase theta-helicase promotes end joining by stripping single-stranded DNA-binding proteins and bridging DNA ends. Nucleic Acids Res 2022; 50:3911-3921. [PMID: 35357490 PMCID: PMC9023281 DOI: 10.1093/nar/gkac119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 01/20/2022] [Accepted: 03/29/2022] [Indexed: 01/20/2023] Open
Abstract
Homologous recombination-deficient cancers rely on DNA polymerase Theta (Polθ)-Mediated End Joining (TMEJ), an alternative double-strand break repair pathway. Polθ is the only vertebrate polymerase that encodes an N-terminal superfamily 2 (SF2) helicase domain, but the role of this helicase domain in TMEJ remains unclear. Using single-molecule imaging, we demonstrate that Polθ-helicase (Polθ-h) is a highly processive single-stranded DNA (ssDNA) motor protein that can efficiently strip Replication Protein A (RPA) from ssDNA. Polθ-h also has a limited capacity for disassembling RAD51 filaments but is not processive on double-stranded DNA. Polθ-h can bridge two non-complementary DNA strands in trans. PARylation of Polθ-h by PARP-1 resolves these DNA bridges. We conclude that Polθ-h removes RPA and RAD51 filaments and mediates bridging of DNA overhangs to aid in polymerization by the Polθ polymerase domain.
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Affiliation(s)
- Jeffrey M Schaub
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Michael M Soniat
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Ilya J Finkelstein
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA.,Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX 78712, USA
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59
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Niewolik D, Schwarz K. Physical ARTEMIS:DNA-PKcs interaction is necessary for V(D)J recombination. Nucleic Acids Res 2022; 50:2096-2110. [PMID: 35150269 PMCID: PMC8887466 DOI: 10.1093/nar/gkac071] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 01/12/2022] [Accepted: 01/25/2022] [Indexed: 02/06/2023] Open
Abstract
The nuclease ARTEMIS and the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) are involved in the repair of physiological and pathogenic DNA double strand breaks. Both proteins are indispensable for the hairpin-opening activity in V(D)J recombination and therefore essential for the adaptive immune response. ARTEMIS and DNA-PKcs interact, however experimental evidence for in vivo significance is missing. We demonstrate that mutations abolishing this protein-protein interaction affect nuclease function. In DNA-PKcs, mutation L3062R impairs the physical interaction with ARTEMIS and was previously identified as pathogenic variant, resulting in radiosensitive severe combined immunodeficiency. In ARTEMIS, specific mutations in two conserved regions affect interaction with DNA-PKcs. In combination they impair V(D)J recombination activity, independent of ARTEMIS autoinhibitory self-interaction between the ARTEMIS C-terminus and the N-terminal nuclease domain. We describe small fragments from both proteins, capable of interaction with the corresponding full-length partner proteins: In DNA-PKcs 42 amino acids out of FAT region 2 (PKcs3041-3082) can mediate interaction with ARTEMIS. In the nuclease we have defined 26 amino acids (ARM378-403) as minimal DNA-PKcs interacting fragment. The exact mapping of the ARTEMIS:DNA-PKcs interaction may pave the way for the design of specific inhibitors targeting the repair of DNA double strand breaks.
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Affiliation(s)
- Doris Niewolik
- Institute for Transfusion Medicine, University of Ulm, Ulm 89081, Germany
| | - Klaus Schwarz
- Institute for Transfusion Medicine, University of Ulm, Ulm 89081, Germany.,Institute for Clinical Transfusion Medicine and Immunogenetics Ulm, German Red Cross Blood Service Baden-Wuerttemberg-Hessen, Ulm 89081, Germany
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60
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Nambiar TS, Baudrier L, Billon P, Ciccia A. CRISPR-based genome editing through the lens of DNA repair. Mol Cell 2022; 82:348-388. [PMID: 35063100 PMCID: PMC8887926 DOI: 10.1016/j.molcel.2021.12.026] [Citation(s) in RCA: 76] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 12/18/2021] [Accepted: 12/20/2021] [Indexed: 01/22/2023]
Abstract
Genome editing technologies operate by inducing site-specific DNA perturbations that are resolved by cellular DNA repair pathways. Products of genome editors include DNA breaks generated by CRISPR-associated nucleases, base modifications induced by base editors, DNA flaps created by prime editors, and integration intermediates formed by site-specific recombinases and transposases associated with CRISPR systems. Here, we discuss the cellular processes that repair CRISPR-generated DNA lesions and describe strategies to obtain desirable genomic changes through modulation of DNA repair pathways. Advances in our understanding of the DNA repair circuitry, in conjunction with the rapid development of innovative genome editing technologies, promise to greatly enhance our ability to improve food production, combat environmental pollution, develop cell-based therapies, and cure genetic and infectious diseases.
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Affiliation(s)
- Tarun S. Nambiar
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032
| | - Lou Baudrier
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive N. W., Calgary, Alberta T2N 4N1, Canada
| | - Pierre Billon
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive N. W., Calgary, Alberta T2N 4N1, Canada,Corresponding authors: ,
| | - Alberto Ciccia
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032,Lead Contact,Corresponding authors: ,
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61
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Structural insights into inhibitor regulation of the DNA repair protein DNA-PKcs. Nature 2022; 601:643-648. [PMID: 34987222 PMCID: PMC8791830 DOI: 10.1038/s41586-021-04274-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 11/19/2021] [Indexed: 01/29/2023]
Abstract
The DNA-dependent protein kinase catalytic subunit (DNA-PKcs) has a central role in non-homologous end joining, one of the two main pathways that detect and repair DNA double-strand breaks (DSBs) in humans1,2. DNA-PKcs is of great importance in repairing pathological DSBs, making DNA-PKcs inhibitors attractive therapeutic agents for cancer in combination with DSB-inducing radiotherapy and chemotherapy3. Many of the selective inhibitors of DNA-PKcs that have been developed exhibit potential as treatment for various cancers4. Here we report cryo-electron microscopy (cryo-EM) structures of human DNA-PKcs natively purified from HeLa cell nuclear extracts, in complex with adenosine-5′-(γ-thio)-triphosphate (ATPγS) and four inhibitors (wortmannin, NU7441, AZD7648 and M3814), including drug candidates undergoing clinical trials. The structures reveal molecular details of ATP binding at the active site before catalysis and provide insights into the modes of action and specificities of the competitive inhibitors. Of note, binding of the ligands causes movement of the PIKK regulatory domain (PRD), revealing a connection between the p-loop and PRD conformations. Electrophoretic mobility shift assay and cryo-EM studies on the DNA-dependent protein kinase holoenzyme further show that ligand binding does not have a negative allosteric or inhibitory effect on assembly of the holoenzyme complex and that inhibitors function through direct competition with ATP. Overall, the structures described in this study should greatly assist future efforts in rational drug design targeting DNA-PKcs, demonstrating the potential of cryo-EM in structure-guided drug development for large and challenging targets. Cryo-electron microscopy structures of DNA-dependent protein kinase catalytic subunit bound to ATPγS and four inhibitors (wortmannin, NU7441, AZD7648 and M3814) provide molecular details and insights useful for drug design.
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62
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Rempfer C, Wiedemann G, Schween G, Kerres KL, Lucht JM, Horres R, Decker EL, Reski R. Autopolyploidization affects transcript patterns and gene targeting frequencies in Physcomitrella. PLANT CELL REPORTS 2022; 41:153-173. [PMID: 34636965 PMCID: PMC8803787 DOI: 10.1007/s00299-021-02794-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 09/23/2021] [Indexed: 06/13/2023]
Abstract
In Physcomitrella, whole-genome duplications affected the expression of about 3.7% of the protein-encoding genes, some of them relevant for DNA repair, resulting in a massively reduced gene-targeting frequency. Qualitative changes in gene expression after an autopolyploidization event, a pure duplication of the whole genome (WGD), might be relevant for a different regulation of molecular mechanisms between angiosperms growing in a life cycle with a dominant diploid sporophytic stage and the haploid-dominant mosses. Whereas angiosperms repair DNA double-strand breaks (DSB) preferentially via non-homologous end joining (NHEJ), in the moss Physcomitrella homologous recombination (HR) is the main DNA-DSB repair pathway. HR facilitates the precise integration of foreign DNA into the genome via gene targeting (GT). Here, we studied the influence of ploidy on gene expression patterns and GT efficiency in Physcomitrella using haploid plants and autodiploid plants, generated via an artificial WGD. Single cells (protoplasts) were transfected with a GT construct and material from different time-points after transfection was analysed by microarrays and SuperSAGE sequencing. In the SuperSAGE data, we detected 3.7% of the Physcomitrella genes as differentially expressed in response to the WGD event. Among the differentially expressed genes involved in DNA-DSB repair was an upregulated gene encoding the X-ray repair cross-complementing protein 4 (XRCC4), a key player in NHEJ. Analysing the GT efficiency, we observed that autodiploid plants were significantly GT suppressed (p < 0.001) attaining only one third of the expected GT rates. Hence, an alteration of global transcript patterns, including genes related to DNA repair, in autodiploid Physcomitrella plants correlated with a drastic suppression of HR.
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Affiliation(s)
- Christine Rempfer
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, 79104, Freiburg, Germany
| | - Gertrud Wiedemann
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
- Department of Hematology and Central Hematology Laboratory, Inselspital, Bern University Hospital, University of Bern, 3010, Bern, Switzerland
| | - Gabriele Schween
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
- Corteva Agriscience, Pioneer Hi-Bred Northern Europe, Münstertäler Strasse 26, 79427, Eschbach, Germany
| | - Klaus L Kerres
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
| | - Jan M Lucht
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
- Scienceindustries, Nordstrasse 15, 8006, Zurich, Switzerland
| | - Ralf Horres
- GenXPro GmbH, Altenhöferallee 3, 60438, Frankfurt am Main, Germany
| | - Eva L Decker
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
| | - Ralf Reski
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany.
- Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, 79104, Freiburg, Germany.
- Signalling Research Centres BIOSS and CIBSS, Schaenzlestr. 18, 79104, Freiburg, Germany.
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63
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Liu D, Lieber MR. The mechanisms of human lymphoid chromosomal translocations and their medical relevance. Crit Rev Biochem Mol Biol 2021; 57:227-243. [PMID: 34875186 DOI: 10.1080/10409238.2021.2004576] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The most common human lymphoid chromosomal translocations involve concurrent failures of the recombination activating gene (RAG) complex and Activation-Induced Deaminase (AID). These are two enzymes that are normally expressed for purposes of the two site-specific DNA recombination processes: V(D)J recombination and class switch recombination (CSR). First, though it is rare, a low level of expression of AID can introduce long-lived T:G mismatch lesions at 20-600 bp fragile zones. Second, the V(D)J recombination process can occasionally fail to rejoin coding ends, and this failure may permit an opportunity for Artemis:DNA-dependent kinase catalytic subunit (DNA-PKcs) to convert the T:G mismatch sites at the fragile zones into double-strand breaks. The 20-600 bp fragile zones must be, at least transiently, in a single-stranded DNA (ssDNA) state for the first step to occur, because AID only acts on ssDNA. Here we discuss the key DNA sequence features that lead to AID action at a fragile zone, which are (a) the proximity and density of strings of cytosine nucleotides (C-strings) that cause a B/A-intermediate DNA conformation; (b) overlapping AID hotspots that contain a methyl CpG (WRCG), which AID converts to a long-lived T:G mismatch; and (c) transcription, which, though not essential, favors increased ssDNA in the fragile zone. We also summarize chromosomal features of the focal fragile zones in lymphoid malignancies and discuss the clinical relevance of understanding the translocation mechanisms. Many of the key principles covered here are also relevant to chromosomal translocations in non-lymphoid somatic cells as well.
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Affiliation(s)
- Di Liu
- Department of Pathology & Laboratory Medicine, Department of Biochemistry & Molecular Biology, Department of Molecular Microbiology and Immunology, and Section of Computational Biology in the Department of Biological Sciences, USC Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Michael R Lieber
- Department of Pathology & Laboratory Medicine, Department of Biochemistry & Molecular Biology, Department of Molecular Microbiology and Immunology, and Section of Computational Biology in the Department of Biological Sciences, USC Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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64
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Kong M, Greene EC. Mechanistic Insights From Single-Molecule Studies of Repair of Double Strand Breaks. Front Cell Dev Biol 2021; 9:745311. [PMID: 34869333 PMCID: PMC8636147 DOI: 10.3389/fcell.2021.745311] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/28/2021] [Indexed: 01/01/2023] Open
Abstract
DNA double strand breaks (DSBs) are among some of the most deleterious forms of DNA damage. Left unrepaired, they are detrimental to genome stability, leading to high risk of cancer. Two major mechanisms are responsible for the repair of DSBs, homologous recombination (HR) and nonhomologous end joining (NHEJ). The complex nature of both pathways, involving a myriad of protein factors functioning in a highly coordinated manner at distinct stages of repair, lend themselves to detailed mechanistic studies using the latest single-molecule techniques. In avoiding ensemble averaging effects inherent to traditional biochemical or genetic methods, single-molecule studies have painted an increasingly detailed picture for every step of the DSB repair processes.
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Affiliation(s)
| | - Eric C. Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, United States
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65
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Chen Y, Li Y, Xiong J, Lan B, Wang X, Liu J, Lin J, Fei Z, Zheng X, Chen C. Role of PRKDC in cancer initiation, progression, and treatment. Cancer Cell Int 2021; 21:563. [PMID: 34702253 PMCID: PMC8547028 DOI: 10.1186/s12935-021-02229-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 09/24/2021] [Indexed: 01/29/2023] Open
Abstract
The PRKDC gene encodes the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) protein. DNA-PKcs plays an important role in nonhomologous end joining (NHEJ) of DNA double-strand breaks (DSBs) and is also closely related to the establishment of central immune tolerance and the maintenance of chromosome stability. The occurrence and development of different types of tumors and the results of their treatment are also influenced by DNA-PKcs, and it may also predict the results of radiotherapy, chemotherapy, and therapy with immune checkpoint inhibitors (ICIs). Here, we discuss and review the structure and mechanism of action of PRKDC and DNA-PKcs and their relationship with cancer.
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Affiliation(s)
- Yu Chen
- Department of Medical Oncology, Fujian Medical University Cancer Hospital & Fujian Cancer Hospital, Fuzhou, Fujian Province, China.,Cancer Bio-Immunotherapy Center, Fujian Medical University Cancer Hospital & Fujian Cancer Hospital, Fuzhou, Fujian Province, China.,Fujian Provincial Key Laboratory of Translational Cancer Medicine, Fuzhou, Fujian Province, China
| | - Yi Li
- Department of Radiation Oncology, Fujian Medical University Cancer Hospital & Fujian Cancer Hospital, Fuzhou, Fujian Province, China
| | - Jiani Xiong
- Department of Medical Oncology, Fujian Medical University Cancer Hospital & Fujian Cancer Hospital, Fuzhou, Fujian Province, China.,Cancer Bio-Immunotherapy Center, Fujian Medical University Cancer Hospital & Fujian Cancer Hospital, Fuzhou, Fujian Province, China
| | - Bin Lan
- Department of Medical Oncology, Fujian Medical University Cancer Hospital & Fujian Cancer Hospital, Fuzhou, Fujian Province, China.,Shanghai Center for Systems Biomedicine Research, Shanghai Jiao Tong University, Shanghai, China
| | - Xuefeng Wang
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China.,The First Affiliated Hospital of Soochow University and State Key Laboratory of Radiation Medicine and Protection, Institutes for Translational Medicine, Soochow University, Suzhou, Jiangsu, China
| | - Jun Liu
- Department of Medical Oncology, Fujian Medical University Cancer Hospital & Fujian Cancer Hospital, Fuzhou, Fujian Province, China.,Cancer Bio-Immunotherapy Center, Fujian Medical University Cancer Hospital & Fujian Cancer Hospital, Fuzhou, Fujian Province, China
| | - Jing Lin
- Department of Medical Oncology, Fujian Medical University Cancer Hospital & Fujian Cancer Hospital, Fuzhou, Fujian Province, China.,Cancer Bio-Immunotherapy Center, Fujian Medical University Cancer Hospital & Fujian Cancer Hospital, Fuzhou, Fujian Province, China.,Fujian Provincial Key Laboratory of Translational Cancer Medicine, Fuzhou, Fujian Province, China
| | - Zhaodong Fei
- Department of Radiation Oncology, Fujian Medical University Cancer Hospital & Fujian Cancer Hospital, Fuzhou, Fujian Province, China
| | - Xiaobin Zheng
- Cancer Bio-Immunotherapy Center, Fujian Medical University Cancer Hospital & Fujian Cancer Hospital, Fuzhou, Fujian Province, China.,Department of Radiation Oncology, Fujian Medical University Cancer Hospital & Fujian Cancer Hospital, Fuzhou, Fujian Province, China
| | - Chuanben Chen
- Cancer Bio-Immunotherapy Center, Fujian Medical University Cancer Hospital & Fujian Cancer Hospital, Fuzhou, Fujian Province, China. .,Fujian Provincial Key Laboratory of Translational Cancer Medicine, Fuzhou, Fujian Province, China. .,Department of Radiation Oncology, Fujian Medical University Cancer Hospital & Fujian Cancer Hospital, Fuzhou, Fujian Province, China.
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66
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Frock RL, Sadeghi C, Meng J, Wang JL. DNA End Joining: G0-ing to the Core. Biomolecules 2021; 11:biom11101487. [PMID: 34680120 PMCID: PMC8533500 DOI: 10.3390/biom11101487] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/05/2021] [Accepted: 10/06/2021] [Indexed: 12/28/2022] Open
Abstract
Humans have evolved a series of DNA double-strand break (DSB) repair pathways to efficiently and accurately rejoin nascently formed pairs of double-stranded DNA ends (DSEs). In G0/G1-phase cells, non-homologous end joining (NHEJ) and alternative end joining (A-EJ) operate to support covalent rejoining of DSEs. While NHEJ is predominantly utilized and collaborates extensively with the DNA damage response (DDR) to support pairing of DSEs, much less is known about A-EJ collaboration with DDR factors when NHEJ is absent. Non-cycling lymphocyte progenitor cells use NHEJ to complete V(D)J recombination of antigen receptor genes, initiated by the RAG1/2 endonuclease which holds its pair of targeted DSBs in a synapse until each specified pair of DSEs is handed off to the NHEJ DSB sensor complex, Ku. Similar to designer endonuclease DSBs, the absence of Ku allows for A-EJ to access RAG1/2 DSEs but with random pairing to complete their repair. Here, we describe recent insights into the major phases of DSB end joining, with an emphasis on synapsis and tethering mechanisms, and bring together new and old concepts of NHEJ vs. A-EJ and on RAG2-mediated repair pathway choice.
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67
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Chaplin AK, Hardwick SW, Stavridi AK, Buehl CJ, Goff NJ, Ropars V, Liang S, De Oliveira TM, Chirgadze DY, Meek K, Charbonnier JB, Blundell TL. Cryo-EM of NHEJ supercomplexes provides insights into DNA repair. Mol Cell 2021; 81:3400-3409.e3. [PMID: 34352203 PMCID: PMC9006396 DOI: 10.1016/j.molcel.2021.07.005] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/16/2021] [Accepted: 07/06/2021] [Indexed: 01/12/2023]
Abstract
Non-homologous end joining (NHEJ) is one of two critical mechanisms utilized in humans to repair DNA double-strand breaks (DSBs). Unrepaired or incorrect repair of DSBs can lead to apoptosis or cancer. NHEJ involves several proteins, including the Ku70/80 heterodimer, DNA-dependent protein kinase catalytic subunit (DNA-PKcs), X-ray cross-complementing protein 4 (XRCC4), XRCC4-like factor (XLF), and ligase IV. These core proteins bind DSBs and ligate the damaged DNA ends. However, details of the structural assembly of these proteins remain unclear. Here, we present cryo-EM structures of NHEJ supercomplexes that are composed of these core proteins and DNA, revealing the detailed structural architecture of this assembly. We describe monomeric and dimeric forms of this supercomplex and also propose the existence of alternate dimeric forms of long-range synaptic complexes. Finally, we show that mutational disruption of several structural features within these NHEJ complexes negatively affects DNA repair.
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Affiliation(s)
- Amanda K Chaplin
- Department of Biochemistry, University of Cambridge, Sanger Building, Tennis Court Road, Cambridge CB2 1GA, UK.
| | - Steven W Hardwick
- CryoEM Facility, Department of Biochemistry, University of Cambridge, Sanger Building, Tennis Court Road, Cambridge CB2 1GA, UK
| | - Antonia Kefala Stavridi
- Department of Biochemistry, University of Cambridge, Sanger Building, Tennis Court Road, Cambridge CB2 1GA, UK
| | - Christopher J Buehl
- College of Veterinary Medicine, Department of Microbiology & Molecular Genetics, Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Noah J Goff
- College of Veterinary Medicine, Department of Microbiology & Molecular Genetics, Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Virginie Ropars
- Institute for Integrative Biology of the Cell (I2BC), Institute Joliot, CEA, CNRS, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France
| | - Shikang Liang
- Department of Biochemistry, University of Cambridge, Sanger Building, Tennis Court Road, Cambridge CB2 1GA, UK
| | | | - Dimitri Y Chirgadze
- CryoEM Facility, Department of Biochemistry, University of Cambridge, Sanger Building, Tennis Court Road, Cambridge CB2 1GA, UK
| | - Katheryn Meek
- College of Veterinary Medicine, Department of Microbiology & Molecular Genetics, Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Jean-Baptiste Charbonnier
- Institute for Integrative Biology of the Cell (I2BC), Institute Joliot, CEA, CNRS, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France
| | - Tom L Blundell
- Department of Biochemistry, University of Cambridge, Sanger Building, Tennis Court Road, Cambridge CB2 1GA, UK.
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68
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Liang S, Chaplin AK, Stavridi AK, Appleby R, Hnizda A, Blundell TL. Stages, scaffolds and strings in the spatial organisation of non-homologous end joining: Insights from X-ray diffraction and Cryo-EM. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 163:60-73. [PMID: 33285184 PMCID: PMC8224183 DOI: 10.1016/j.pbiomolbio.2020.11.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 11/26/2020] [Indexed: 01/10/2023]
Abstract
Non-homologous end joining (NHEJ) is the preferred pathway for the repair of DNA double-strand breaks in humans. Here we describe three structural aspects of the repair pathway: stages, scaffolds and strings. We discuss the orchestration of DNA repair to guarantee robust and efficient NHEJ. We focus on structural studies over the past two decades, not only using X-ray diffraction, but also increasingly exploiting cryo-EM to investigate the macromolecular assemblies.
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Affiliation(s)
- Shikang Liang
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, Cambridgeshire, UK
| | - Amanda K Chaplin
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, Cambridgeshire, UK
| | - Antonia Kefala Stavridi
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, Cambridgeshire, UK
| | - Robert Appleby
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, Cambridgeshire, UK
| | - Ales Hnizda
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, Cambridgeshire, UK
| | - Tom L Blundell
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, Cambridgeshire, UK.
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69
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Ackerson SM, Romney C, Schuck PL, Stewart JA. To Join or Not to Join: Decision Points Along the Pathway to Double-Strand Break Repair vs. Chromosome End Protection. Front Cell Dev Biol 2021; 9:708763. [PMID: 34322492 PMCID: PMC8311741 DOI: 10.3389/fcell.2021.708763] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 06/17/2021] [Indexed: 01/01/2023] Open
Abstract
The regulation of DNA double-strand breaks (DSBs) and telomeres are diametrically opposed in the cell. DSBs are considered one of the most deleterious forms of DNA damage and must be quickly recognized and repaired. Telomeres, on the other hand, are specialized, stable DNA ends that must be protected from recognition as DSBs to inhibit unwanted chromosome fusions. Decisions to join DNA ends, or not, are therefore critical to genome stability. Yet, the processing of telomeres and DSBs share many commonalities. Accordingly, key decision points are used to shift DNA ends toward DSB repair vs. end protection. Additionally, DSBs can be repaired by two major pathways, namely homologous recombination (HR) and non-homologous end joining (NHEJ). The choice of which repair pathway is employed is also dictated by a series of decision points that shift the break toward HR or NHEJ. In this review, we will focus on these decision points and the mechanisms that dictate end protection vs. DSB repair and DSB repair choice.
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Affiliation(s)
- Stephanie M Ackerson
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - Carlan Romney
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - P Logan Schuck
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - Jason A Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
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70
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Fuchs RP, Isogawa A, Paulo JA, Onizuka K, Takahashi T, Amunugama R, Duxin JP, Fujii S. Crosstalk between repair pathways elicits double-strand breaks in alkylated DNA and implications for the action of temozolomide. eLife 2021; 10:e69544. [PMID: 34236314 PMCID: PMC8289412 DOI: 10.7554/elife.69544] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 07/07/2021] [Indexed: 12/12/2022] Open
Abstract
Temozolomide (TMZ), a DNA methylating agent, is the primary chemotherapeutic drug used in glioblastoma treatment. TMZ induces mostly N-alkylation adducts (N7-methylguanine and N3-methyladenine) and some O6-methylguanine (O6mG) adducts. Current models propose that during DNA replication, thymine is incorporated across from O6mG, promoting a futile cycle of mismatch repair (MMR) that leads to DNA double-strand breaks (DSBs). To revisit the mechanism of O6mG processing, we reacted plasmid DNA with N-methyl-N-nitrosourea (MNU), a temozolomide mimic, and incubated it in Xenopus egg-derived extracts. We have shown that in this system, MMR proteins are enriched on MNU-treated DNA and we observed robust, MMR-dependent, repair synthesis. Our evidence also suggests that MMR, initiated at O6mG:C sites, is strongly stimulated in cis by repair processing of other lesions, such as N-alkylation adducts. Importantly, MNU-treated plasmids display DSBs in extracts, the frequency of which increases linearly with the square of alkylation dose. We suggest that DSBs result from two independent repair processes, one involving MMR at O6mG:C sites and the other involving base excision repair acting at a nearby N-alkylation adduct. We propose a new, replication-independent mechanism of action of TMZ, which operates in addition to the well-studied cell cycle-dependent mode of action.
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Affiliation(s)
- Robert P Fuchs
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical SchoolBostonUnited States
| | - Asako Isogawa
- Cancer Research Center of Marseille, UMR7258, CNRSMarseilleFrance
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical SchoolBostonUnited States
| | - Kazumitsu Onizuka
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku UniversitySendaiJapan
| | | | - Ravindra Amunugama
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical SchoolBostonUnited States
| | - Julien P Duxin
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical SchoolBostonUnited States
| | - Shingo Fujii
- Cancer Research Center of Marseille, UMR7258, CNRSMarseilleFrance
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71
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Fijen C, Rothenberg E. The evolving complexity of DNA damage foci: RNA, condensates and chromatin in DNA double-strand break repair. DNA Repair (Amst) 2021; 105:103170. [PMID: 34256335 DOI: 10.1016/j.dnarep.2021.103170] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 06/08/2021] [Accepted: 06/28/2021] [Indexed: 02/06/2023]
Abstract
Formation of biomolecular condensates is increasingly recognized as a mechanism employed by cells to deal with stress and to optimize enzymatic reactions. Recent studies have characterized several DNA repair foci as phase-separated condensates, behaving like liquid droplets. Concomitantly, the apparent importance of long non-coding RNAs and RNA-binding proteins for the repair of double-strand breaks has raised many questions about their exact contribution to the repair process. Here we discuss how RNA molecules can participate in condensate formation and how RNA-binding proteins can act as molecular scaffolds. We furthermore summarize our current knowledge about how properties of condensates can influence the choice of repair pathway (homologous recombination or non-homologous end joining) and identify the open questions in this field of emerging importance.
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Affiliation(s)
- Carel Fijen
- Department of Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, USA.
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, USA.
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72
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Hammel M, Tainer JA. X-ray scattering reveals disordered linkers and dynamic interfaces in complexes and mechanisms for DNA double-strand break repair impacting cell and cancer biology. Protein Sci 2021; 30:1735-1756. [PMID: 34056803 PMCID: PMC8376411 DOI: 10.1002/pro.4133] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 05/23/2021] [Accepted: 05/25/2021] [Indexed: 12/17/2022]
Abstract
Evolutionary selection ensures specificity and efficiency in dynamic metastable macromolecular machines that repair DNA damage without releasing toxic and mutagenic intermediates. Here we examine non‐homologous end joining (NHEJ) as the primary conserved DNA double‐strand break (DSB) repair process in human cells. NHEJ has exemplary key roles in networks determining the development, outcome of cancer treatments by DSB‐inducing agents, generation of antibody and T‐cell receptor diversity, and innate immune response for RNA viruses. We determine mechanistic insights into NHEJ structural biochemistry focusing upon advanced small angle X‐ray scattering (SAXS) results combined with X‐ray crystallography (MX) and cryo‐electron microscopy (cryo‐EM). SAXS coupled to atomic structures enables integrated structural biology for objective quantitative assessment of conformational ensembles and assemblies in solution, intra‐molecular distances, structural similarity, functional disorder, conformational switching, and flexibility. Importantly, NHEJ complexes in solution undergo larger allosteric transitions than seen in their cryo‐EM or MX structures. In the long‐range synaptic complex, X‐ray repair cross‐complementing 4 (XRCC4) plus XRCC4‐like‐factor (XLF) form a flexible bridge and linchpin for DNA ends bound to KU heterodimer (Ku70/80) and DNA‐PKcs (DNA‐dependent protein kinase catalytic subunit). Upon binding two DNA ends, auto‐phosphorylation opens DNA‐PKcs dimer licensing NHEJ via concerted conformational transformations of XLF‐XRCC4, XLF–Ku80, and LigIVBRCT–Ku70 interfaces. Integrated structures reveal multifunctional roles for disordered linkers and modular dynamic interfaces promoting DSB end processing and alignment into the short‐range complex for ligation by LigIV. Integrated findings define dynamic assemblies fundamental to designing separation‐of‐function mutants and allosteric inhibitors targeting conformational transitions in multifunctional complexes.
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Affiliation(s)
- Michal Hammel
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - John A Tainer
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California, USA.,Department of Cancer Biology, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.,Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
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73
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Cell Cycle Checkpoints Cooperate to Suppress DNA- and RNA-Associated Molecular Pattern Recognition and Anti-Tumor Immune Responses. Cell Rep 2021; 32:108080. [PMID: 32877684 PMCID: PMC7530826 DOI: 10.1016/j.celrep.2020.108080] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 06/22/2020] [Accepted: 08/05/2020] [Indexed: 12/19/2022] Open
Abstract
The DNA-dependent pattern recognition receptor, cGAS (cyclic GMP-AMP synthase), mediates communication between the DNA damage and the immune responses. Mitotic chromosome missegregation stimulates cGAS activity; however, it is unclear whether progression through mitosis is required for cancercell-intrinsic activation of anti-tumor immune responses. Moreover, it is unknown whether cell cycle checkpoint disruption can restore responses in cancer cells that are recalcitrant to DNAdamage-induced inflammation. Here, we demonstrate that prolonged cell cycle arrest at the G2-mitosis boundary from either excessive DNA damage or CDK1 inhibition prevents inflammatory-stimulated gene expression and immune-mediated destruction of distal tumors. Remarkably, DNAdamage-induced inflammatory signaling is restored in a RIG-I-dependent manner upon concomitant disruption of p53 and the G2 checkpoint. These findings link aberrant cell progression and p53 loss to an expanded spectrum of damage-associated molecular pattern recognition and have implications for the design of rational approaches to augment anti-tumor immune responses. Chen et al. show that prolonged cell cycle arrest before mitosis prevents inflammatory signaling and anti-tumor immunity. Concomitant disruption of p53 and the G2 checkpoint restores DNAdamage-induced inflammatory signaling in a cGAS- and RIG-I-dependent manner.
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Qi Y, Warmenhoven JW, Henthorn NT, Ingram SP, Xu XG, Kirkby KJ, Merchant MJ. Mechanistic Modelling of Slow and Fast NHEJ DNA Repair Pathways Following Radiation for G0/G1 Normal Tissue Cells. Cancers (Basel) 2021; 13:2202. [PMID: 34063683 PMCID: PMC8124137 DOI: 10.3390/cancers13092202] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/23/2021] [Accepted: 04/29/2021] [Indexed: 01/12/2023] Open
Abstract
Mechanistic in silico models can provide insight into biological mechanisms and highlight uncertainties for experimental investigation. Radiation-induced double-strand breaks (DSBs) are known to be toxic lesions if not repaired correctly. Non-homologous end joining (NHEJ) is the major DSB-repair pathway available throughout the cell cycle and, recently, has been hypothesised to consist of a fast and slow component in G0/G1. The slow component has been shown to be resection-dependent, requiring the nuclease Artemis to function. However, the pathway is not yet fully understood. This study compares two hypothesised models, simulating the action of individual repair proteins on DSB ends in a step-by-step manner, enabling the modelling of both wild-type and protein-deficient cell systems. Performance is benchmarked against experimental data from 21 cell lines and 18 radiation qualities. A model where resection-dependent and independent pathways are entirely separated can only reproduce experimental repair kinetics with additional restraints on end motion and protein recruitment. However, a model where the pathways are entwined was found to effectively fit without needing additional mechanisms. It has been shown that DaMaRiS is a useful tool when analysing the connections between resection-dependent and independent NHEJ repair pathways and robustly matches with experimental results from several sources.
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Affiliation(s)
- Yaping Qi
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China;
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (J.W.W.); (N.T.H.); (S.P.I.); (K.J.K.); (M.J.M.)
| | - John William Warmenhoven
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (J.W.W.); (N.T.H.); (S.P.I.); (K.J.K.); (M.J.M.)
- The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9PL, UK
| | - Nicholas Thomas Henthorn
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (J.W.W.); (N.T.H.); (S.P.I.); (K.J.K.); (M.J.M.)
- The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9PL, UK
| | - Samuel Peter Ingram
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (J.W.W.); (N.T.H.); (S.P.I.); (K.J.K.); (M.J.M.)
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester M13 9PL, UK
| | - Xie George Xu
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China;
| | - Karen Joy Kirkby
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (J.W.W.); (N.T.H.); (S.P.I.); (K.J.K.); (M.J.M.)
- The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9PL, UK
| | - Michael John Merchant
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (J.W.W.); (N.T.H.); (S.P.I.); (K.J.K.); (M.J.M.)
- The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9PL, UK
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75
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Chen S, Lee L, Naila T, Fishbain S, Wang A, Tomkinson AE, Lees-Miller SP, He Y. Structural basis of long-range to short-range synaptic transition in NHEJ. Nature 2021; 593:294-298. [PMID: 33854234 PMCID: PMC8122075 DOI: 10.1038/s41586-021-03458-7] [Citation(s) in RCA: 88] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/15/2021] [Indexed: 02/07/2023]
Abstract
DNA double-strand breaks (DSBs) are a highly cytotoxic form of DNA damage and the incorrect repair of DSBs is linked to carcinogenesis1,2. The conserved error-prone non-homologous end joining (NHEJ) pathway has a key role in determining the effects of DSB-inducing agents that are used to treat cancer as well as the generation of the diversity in antibodies and T cell receptors2,3. Here we applied single-particle cryo-electron microscopy to visualize two key DNA-protein complexes that are formed by human NHEJ factors. The Ku70/80 heterodimer (Ku), the catalytic subunit of the DNA-dependent protein kinase (DNA-PKcs), DNA ligase IV (LigIV), XRCC4 and XLF form a long-range synaptic complex, in which the DNA ends are held approximately 115 Å apart. Two DNA end-bound subcomplexes comprising Ku and DNA-PKcs are linked by interactions between the DNA-PKcs subunits and a scaffold comprising LigIV, XRCC4, XLF, XRCC4 and LigIV. The relative orientation of the DNA-PKcs molecules suggests a mechanism for autophosphorylation in trans, which leads to the dissociation of DNA-PKcs and the transition into the short-range synaptic complex. Within this complex, the Ku-bound DNA ends are aligned for processing and ligation by the XLF-anchored scaffold, and a single catalytic domain of LigIV is stably associated with a nick between the two Ku molecules, which suggests that the joining of both strands of a DSB involves both LigIV molecules.
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Affiliation(s)
- Siyu Chen
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, USA
| | - Linda Lee
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada
- Robson DNA Science Centre, Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta, Canada
| | - Tasmin Naila
- Department of Internal Medicine, University of New Mexico, Albuquerque, NM, USA
- Department of Molecular Genetics & Microbiology, University of New Mexico, Albuquerque, NM, USA
- University of New Mexico Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM, USA
| | - Susan Fishbain
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Annie Wang
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Alan E Tomkinson
- Department of Internal Medicine, University of New Mexico, Albuquerque, NM, USA
- Department of Molecular Genetics & Microbiology, University of New Mexico, Albuquerque, NM, USA
- University of New Mexico Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM, USA
| | - Susan P Lees-Miller
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada
- Robson DNA Science Centre, Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta, Canada
| | - Yuan He
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA.
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, USA.
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, USA.
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Northwestern University, Chicago, IL, USA.
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76
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Ghosh D, Raghavan SC. 20 years of DNA Polymerase μ, the polymerase that still surprises. FEBS J 2021; 288:7230-7242. [DOI: 10.1111/febs.15852] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 03/02/2021] [Accepted: 03/01/2021] [Indexed: 12/22/2022]
Affiliation(s)
- Dipayan Ghosh
- Department of Biochemistry Indian Institute of Science Bangalore India
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77
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Feng XA, Poyton MF, Ha T. Multicolor single-molecule FRET for DNA and RNA processes. Curr Opin Struct Biol 2021; 70:26-33. [PMID: 33894656 DOI: 10.1016/j.sbi.2021.03.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 03/10/2021] [Indexed: 12/31/2022]
Abstract
Single-molecule fluorescence resonance energy transfer (smFRET) is a useful tool for observing the dynamics of protein-nucleic acid interactions. Although most smFRET measurements have used two fluorophores, multicolor smFRET measurements using more than two fluorophores offer more information about how protein-nucleic acid complexes dynamically move, assemble, and disassemble. Multicolor smFRET experiments include three or more fluorophores and at least one donor-acceptor pair. This review highlights how multicolor smFRET is being used to probe the dynamics of three different classes of biochemical processes-protein-DNA interactions, chromatin remodeling, and protein translation.
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Affiliation(s)
- Xinyu A Feng
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA; Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Matthew F Poyton
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Taekjip Ha
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA; Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA; Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD, USA; Howard Hughes Medical Institute, Baltimore, MD, USA.
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78
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Studying chromosome biology with single-molecule resolution in Xenopus laevis egg extracts. Essays Biochem 2021; 65:17-26. [PMID: 33438722 PMCID: PMC8056035 DOI: 10.1042/ebc20200026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 11/16/2020] [Accepted: 11/25/2020] [Indexed: 01/11/2023]
Abstract
Cell-free extracts from Xenopus laevis eggs are a model system for studying chromosome biology. Xenopus egg extracts can be synchronised in different cell cycle stages, making them useful for studying DNA replication, DNA repair and chromosome organisation. Combining single-molecule approaches with egg extracts is an exciting development being used to reveal molecular mechanisms that are difficult to study using conventional approaches. Fluorescence-based single-molecule imaging of surface-tethered DNAs has been used to visualise labelled protein movements on stretched DNA, the dynamics of DNA–protein complexes and extract-dependent structural rearrangement of stained DNA. Force-based single-molecule techniques are an alternative approach to measure mechanics of DNA and proteins. In this essay, the details of these single-molecule techniques, and the insights into chromosome biology they provide, will be discussed.
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79
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Willaume S, Rass E, Fontanilla-Ramirez P, Moussa A, Wanschoor P, Bertrand P. A Link between Replicative Stress, Lamin Proteins, and Inflammation. Genes (Basel) 2021; 12:genes12040552. [PMID: 33918867 PMCID: PMC8070205 DOI: 10.3390/genes12040552] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/23/2021] [Accepted: 04/08/2021] [Indexed: 12/12/2022] Open
Abstract
Double-stranded breaks (DSB), the most toxic DNA lesions, are either a consequence of cellular metabolism, programmed as in during V(D)J recombination, or induced by anti-tumoral therapies or accidental genotoxic exposure. One origin of DSB sources is replicative stress, a major source of genome instability, especially when the integrity of the replication forks is not properly guaranteed. To complete stalled replication, restarting the fork requires complex molecular mechanisms, such as protection, remodeling, and processing. Recently, a link has been made between DNA damage accumulation and inflammation. Indeed, defects in DNA repair or in replication can lead to the release of DNA fragments in the cytosol. The recognition of this self-DNA by DNA sensors leads to the production of inflammatory factors. This beneficial response activating an innate immune response and destruction of cells bearing DNA damage may be considered as a novel part of DNA damage response. However, upon accumulation of DNA damage, a chronic inflammatory cellular microenvironment may lead to inflammatory pathologies, aging, and progression of tumor cells. Progress in understanding the molecular mechanisms of DNA damage repair, replication stress, and cytosolic DNA production would allow to propose new therapeutical strategies against cancer or inflammatory diseases associated with aging. In this review, we describe the mechanisms involved in DSB repair, the replicative stress management, and its consequences. We also focus on new emerging links between key components of the nuclear envelope, the lamins, and DNA repair, management of replicative stress, and inflammation.
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80
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Zou RS, Liu Y, Wu B, Ha T. Cas9 deactivation with photocleavable guide RNAs. Mol Cell 2021; 81:1553-1565.e8. [PMID: 33662274 PMCID: PMC8026597 DOI: 10.1016/j.molcel.2021.02.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 12/23/2020] [Accepted: 02/02/2021] [Indexed: 12/11/2022]
Abstract
Precise control of CRISPR-Cas9 would improve its safety and applicability. Controlled CRISPR inhibition is a promising approach but is complicated by separate inhibitor delivery, incomplete deactivation, and slow kinetics. To overcome these obstacles, we engineered photocleavable guide RNAs (pcRNAs) that endow Cas9 nucleases and base editors with a built-in mechanism for light-based deactivation. pcRNA enabled the fastest (<1 min) and most complete (<1% residual indels) approach for Cas9 deactivation. It also exhibited significantly enhanced specificity with wild-type Cas9. Time-resolved deactivation revealed that 12-36 h of Cas9 activity or 2-4 h of base editor activity was sufficient to achieve high editing efficiency. pcRNA is useful for studies of the cellular response to DNA damage by abolishing sustained cycles of damage and repair that would otherwise desynchronize response trajectories. Together, pcRNA expands the CRISPR toolbox for precision genome editing and studies of DNA damage and repair.
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Affiliation(s)
- Roger S Zou
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Yang Liu
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Bin Wu
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Taekjip Ha
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Biophysics, Johns Hopkins University, Baltimore, MD 21205, USA; Howard Hughes Medical Institute, Baltimore, MD 21205, USA.
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81
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Öz R, Wang JL, Guerois R, Goyal G, KK S, Ropars V, Sharma R, Koca F, Charbonnier JB, Modesti M, Strick TR, Westerlund F. Dynamics of Ku and bacterial non-homologous end-joining characterized using single DNA molecule analysis. Nucleic Acids Res 2021; 49:2629-2641. [PMID: 33590005 PMCID: PMC7969030 DOI: 10.1093/nar/gkab083] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 01/20/2021] [Accepted: 01/29/2021] [Indexed: 01/29/2023] Open
Abstract
We use single-molecule techniques to characterize the dynamics of prokaryotic DNA repair by non-homologous end-joining (NHEJ), a system comprised only of the dimeric Ku and Ligase D (LigD). The Ku homodimer alone forms a ∼2 s synapsis between blunt DNA ends that is increased to ∼18 s upon addition of LigD, in a manner dependent on the C-terminal arms of Ku. The synapsis lifetime increases drastically for 4 nt complementary DNA overhangs, independently of the C-terminal arms of Ku. These observations are in contrast to human Ku, which is unable to bridge either of the two DNA substrates. We also demonstrate that bacterial Ku binds the DNA ends in a cooperative manner for synapsis initiation and remains stably bound at DNA junctions for several hours after ligation is completed, indicating that a system for removal of the proteins is active in vivo. Together these experiments shed light on the dynamics of bacterial NHEJ in DNA end recognition and processing. We speculate on the evolutionary similarities between bacterial and eukaryotic NHEJ and discuss how an increased understanding of bacterial NHEJ can open the door for future antibiotic therapies targeting this mechanism.
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Affiliation(s)
- Robin Öz
- Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg SE 41296, Sweden
| | - Jing L Wang
- Institut Jacques Monod, Université de Paris, CNRS, UMR7592, Paris, France
- Ecole Normale Supérieure, IBENS, CNRS, INSERM, PSL Research University, Paris 75005 France
| | - Raphael Guerois
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette 91198, France
| | - Gaurav Goyal
- Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg SE 41296, Sweden
| | - Sriram KK
- Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg SE 41296, Sweden
| | - Virginie Ropars
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette 91198, France
| | - Rajhans Sharma
- Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg SE 41296, Sweden
| | - Firat Koca
- Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg SE 41296, Sweden
| | - Jean-Baptiste Charbonnier
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette 91198, France
| | - Mauro Modesti
- Cancer Research Center of Marseille, CNRS, Inserm, Institut Paoli-Calmettes, Aix-Marseille Université, Marseille 13009, France
- Equipe Labélisée, Ligue Nationale Contre le Cancer, Paris 75013, France
| | - Terence R Strick
- Institut Jacques Monod, Université de Paris, CNRS, UMR7592, Paris, France
- Ecole Normale Supérieure, IBENS, CNRS, INSERM, PSL Research University, Paris 75005 France
- Equipe Labélisée, Ligue Nationale Contre le Cancer, Paris 75013, France
| | - Fredrik Westerlund
- Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg SE 41296, Sweden
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82
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Abstract
Cells activate their DNA damage response (DDR) in response to DNA virus infection, including adenoviruses, papillomaviruses, polyomaviruses, and herpesviruses. In this study, we found that the DDR kinase pathways activated in normal human fibroblasts by herpes simplex virus 1 (HSV-1) input genomic DNA, HSV-1 replicating DNA, and progeny DNA and in uninfected cells treated with etoposide are different. We also found using clustered regularly interspaced palindromic repeat (CRISPR)-Cas9 technology that different host gene products are required for the DDR in uninfected versus infected cells. Individual DDR components can be proviral or antiviral in that ataxia-telangiectasia mutated (ATM) and p53 promote and Mre11 restricts replication of ICP0-null HSV-1, but ICP0 expression eliminates these DDR effects. Thus, in total, these results argue that HSV-1 manipulates the host cell DDR to utilize specific components for its optimal replication while inactivating the antiviral aspects of the DDR.IMPORTANCE We investigated the relationship between the DNA damage response, a collection of vital cellular pathways that repair potentially lethal damage to the genome, and the DNA virus herpes simplex virus 1. We found that infection by the virus triggers the DNA damage response, and key proteins that mediate this response have opposing effects on the replication and production of progeny viruses. Our work provides novel insights into the relationship between DNA virus infection and the cellular response to the viral genome. We speculate that viral gene products modulate this response, providing potentially novel targets for therapeutic intervention against the virus.
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83
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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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84
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Shen W, Ma Y, Qi H, Wang W, He J, Xiao F, Zhu H, He S. Kinetics model of DNA double-strand break repair in eukaryotes. DNA Repair (Amst) 2021; 100:103035. [PMID: 33618125 DOI: 10.1016/j.dnarep.2020.103035] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 12/11/2020] [Indexed: 11/26/2022]
Abstract
This manuscript outlines the kinetics of two main repair pathways of DNA double-strand break (DSB) in eukaryotes: non-homologous end joining (NHEJ) and homologous recombination repair (HRR). In this review, we discuss the precise study of recruitment kinetics of repair proteins based on the latest technologies in the past two decades. Then we simulate the theoretical description of the DNA repair process by mathematical models. In our study, the consecutive reactions chain (CRC) model and continuous-time random walk (CTRW) model have been unified by us, so that we can obtain the function of the number of intermediates with time in the same framework of equations, overcome the incompatibility between the two models. On this basis, we propose a data fitting workflow using these both models. Finally, we give an overview of different real-time quantitative methods and the new mechanism complexity that can be found from the corresponding dynamic models.
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Affiliation(s)
- Wangtao Shen
- Institute of Biochemistry and Molecular Biology, Hengyang Medical College, University of South China, Hengyang, 421001, China
| | - Yun Ma
- Institute of Biochemistry and Molecular Biology, Hengyang Medical College, University of South China, Hengyang, 421001, China.
| | - Huizhou Qi
- Institute of Biochemistry and Molecular Biology, Hengyang Medical College, University of South China, Hengyang, 421001, China; Function Laboratory Center, Hengyang Medical College, University of South China, Hengyang, 421001, China; Hengyang Key Laboratory for Biological Effects of Nuclear Radiation, University of South China, Hengyang, 421001, China
| | - Wuzhou Wang
- Institute of Biochemistry and Molecular Biology, Hengyang Medical College, University of South China, Hengyang, 421001, China; Hengyang Key Laboratory for Biological Effects of Nuclear Radiation, University of South China, Hengyang, 421001, China
| | - Junyan He
- Department of Radiation Oncology, The First Affiliated Hospital of University of South China, Hengyang, 421001, China
| | - Fangzhu Xiao
- Hengyang Key Laboratory for Biological Effects of Nuclear Radiation, University of South China, Hengyang, 421001, China
| | - Hui Zhu
- Institute of Engineering Mathematics, Mathematics and Physics College, University of South China, Hengyang, 421001, China
| | - Shuya He
- Institute of Biochemistry and Molecular Biology, Hengyang Medical College, University of South China, Hengyang, 421001, China; Hengyang Key Laboratory for Biological Effects of Nuclear Radiation, University of South China, Hengyang, 421001, China.
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85
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Güllülü Ö, Hehlgans S, Mayer BE, Gößner I, Petraki C, Hoffmann M, Dombrowsky MJ, Kunzmann P, Hamacher K, Strebhardt K, Fokas E, Rödel C, Münch C, Rödel F. A Spatial and Functional Interaction of a Heterotetramer Survivin-DNA-PKcs Complex in DNA Damage Response. Cancer Res 2021; 81:2304-2317. [PMID: 33408118 DOI: 10.1158/0008-5472.can-20-2931] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 11/19/2020] [Accepted: 12/28/2020] [Indexed: 11/16/2022]
Abstract
Substantial evidence has shown that overexpression of the inhibitor of apoptosis protein (IAP) survivin in human tumors correlates significantly with treatment resistance and poor patient prognosis. Survivin serves as a radiation resistance factor that impacts the DNA damage response by interacting with DNA-dependent protein kinase (DNA-PKcs). However, the complexity, molecular determinants, and functional consequences of this interrelationship remain largely unknown. By applying coimmunoprecipitation and flow cytometry-based Förster resonance energy transfer assays, we demonstrated a direct involvement of the survivin baculovirus IAP repeat domain in the regulation of radiation survival and DNA repair. This survivin-mediated activity required an interaction of residues S20 and W67 with the phosphoinositide 3-kinase (PI3K) domain of DNA-PKcs. In silico molecular docking and dynamics simulation analyses, in vitro kinase assays, and large-scale mass spectrometry suggested a heterotetrameric survivin-DNA-PKcs complex that results in a conformational change within the DNA-PKcs PI3K domain. Overexpression of survivin resulted in enhanced PI3K enzymatic activity and detection of differentially abundant phosphopeptides and proteins implicated in the DNA damage response. The survivin-DNA-PKcs interaction altered the S/T-hydrophobic motif substrate specificity of DNA-PKcs with a predominant usage of S/T-P phosphorylation sites and an increase of DNA-PKcs substrates including Foxo3. These data demonstrate that survivin differentially regulates DNA-PKcs-dependent radiation survival and DNA double-strand break repair via formation of a survivin-DNA-PKcs heterotetrameric complex. SIGNIFICANCE: These findings provide insight into survivin-mediated regulation of DNA-PKcs kinase and broaden our knowledge of the impact of survivin in modulating the cellular radiation response.See related commentary by Iliakis, p. 2270 GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/9/2304/F1.large.jpg.
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Affiliation(s)
- Ömer Güllülü
- Department of Radiotherapy and Oncology, University Hospital, Goethe University Frankfurt, Germany
| | - Stephanie Hehlgans
- Department of Radiotherapy and Oncology, University Hospital, Goethe University Frankfurt, Germany
| | - Benjamin E Mayer
- Department of Computational Biology and Simulation, Technical University of Darmstadt, Germany
| | - Ines Gößner
- Institute of Biochemistry II, Faculty of Medicine, Goethe University Frankfurt, Germany
| | - Chrysi Petraki
- Department of Radiotherapy and Oncology, University Hospital, Goethe University Frankfurt, Germany
| | - Melanie Hoffmann
- Department of Radiotherapy and Oncology, University Hospital, Goethe University Frankfurt, Germany
| | - Maximilian J Dombrowsky
- Department of Computational Biology and Simulation, Technical University of Darmstadt, Germany
| | - Patrick Kunzmann
- Department of Computational Biology and Simulation, Technical University of Darmstadt, Germany
| | - Kay Hamacher
- Department of Computational Biology and Simulation, Technical University of Darmstadt, Germany
| | - Klaus Strebhardt
- Department of Obstetrics and Gynaecology, University Hospital, Goethe University Frankfurt, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany.,German Cancer Consortium (DKTK) partner site: Frankfurt, Frankfurt am Main, Germany
| | - Emmanouil Fokas
- Department of Radiotherapy and Oncology, University Hospital, Goethe University Frankfurt, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany.,German Cancer Consortium (DKTK) partner site: Frankfurt, Frankfurt am Main, Germany.,Frankfurt Cancer Institute (FCI), Theodor-Stern-Kai 7, Goethe University Frankfurt, Germany
| | - Claus Rödel
- Department of Radiotherapy and Oncology, University Hospital, Goethe University Frankfurt, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany.,German Cancer Consortium (DKTK) partner site: Frankfurt, Frankfurt am Main, Germany.,Frankfurt Cancer Institute (FCI), Theodor-Stern-Kai 7, Goethe University Frankfurt, Germany
| | - Christian Münch
- Institute of Biochemistry II, Faculty of Medicine, Goethe University Frankfurt, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany.,German Cancer Consortium (DKTK) partner site: Frankfurt, Frankfurt am Main, Germany.,Frankfurt Cancer Institute (FCI), Theodor-Stern-Kai 7, Goethe University Frankfurt, Germany
| | - Franz Rödel
- Department of Radiotherapy and Oncology, University Hospital, Goethe University Frankfurt, Germany. .,German Cancer Research Center (DKFZ), Heidelberg, Germany.,German Cancer Consortium (DKTK) partner site: Frankfurt, Frankfurt am Main, Germany.,Frankfurt Cancer Institute (FCI), Theodor-Stern-Kai 7, Goethe University Frankfurt, Germany
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86
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Hepburn M, Saltzberg DJ, Lee L, Fang S, Atkinson C, Strynadka NCJ, Sali A, Lees-Miller SP, Schriemer DC. The active DNA-PK holoenzyme occupies a tensed state in a staggered synaptic complex. Structure 2021; 29:467-478.e6. [PMID: 33412091 DOI: 10.1016/j.str.2020.12.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 11/14/2020] [Accepted: 12/09/2020] [Indexed: 01/06/2023]
Abstract
In the non-homologous end-joining (NHEJ) of a DNA double-strand break, DNA ends are bound and protected by DNA-PK, which synapses across the break to tether the broken ends and initiate repair. There is little clarity surrounding the nature of the synaptic complex and the mechanism governing the transition to repair. We report an integrative structure of the synaptic complex at a precision of 13.5 Å, revealing a symmetric head-to-head arrangement with a large offset in the DNA ends and an extensive end-protection mechanism involving a previously uncharacterized plug domain. Hydrogen/deuterium exchange mass spectrometry identifies an allosteric pathway connecting DNA end-binding with the kinase domain that places DNA-PK under tension in the kinase-active state. We present a model for the transition from end-protection to repair, where the synaptic complex supports hierarchical processing of the ends and scaffold assembly, requiring displacement of the catalytic subunit and tension release through kinase activity.
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Affiliation(s)
- Morgan Hepburn
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada
| | - Daniel J Saltzberg
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Sciences, and California Institute for Quantitative Biomedical Sciences, University of California, San Francisco, CA 94158, USA
| | - Linda Lee
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada
| | - Shujuan Fang
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada
| | - Claire Atkinson
- Department of Biochemistry and Molecular Biology and High-Resolution Macromolecular Electron Microscopy Facility, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Natalie C J Strynadka
- Department of Biochemistry and Molecular Biology and High-Resolution Macromolecular Electron Microscopy Facility, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Sciences, and California Institute for Quantitative Biomedical Sciences, University of California, San Francisco, CA 94158, USA
| | - Susan P Lees-Miller
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada; Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, AB, Canada
| | - David C Schriemer
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada; Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, AB, Canada; Department of Chemistry, University of Calgary, Calgary, AB, Canada.
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87
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Structural insights into the role of DNA-PK as a master regulator in NHEJ. GENOME INSTABILITY & DISEASE 2021; 2:195-210. [PMID: 34723130 PMCID: PMC8549938 DOI: 10.1007/s42764-021-00047-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 07/06/2021] [Accepted: 07/12/2021] [Indexed: 12/26/2022]
Abstract
DNA-dependent protein kinase catalytic subunit DNA-PKcs/PRKDC is the largest serine/threonine protein kinase of the phosphatidyl inositol 3-kinase-like protein kinase (PIKK) family and is the most highly expressed PIKK in human cells. With its DNA-binding partner Ku70/80, DNA-PKcs is required for regulated and efficient repair of ionizing radiation-induced DNA double-strand breaks via the non-homologous end joining (NHEJ) pathway. Loss of DNA-PKcs or other NHEJ factors leads to radiation sensitivity and unrepaired DNA double-strand breaks (DSBs), as well as defects in V(D)J recombination and immune defects. In this review, we highlight the contributions of the late Dr. Carl W. Anderson to the discovery and early characterization of DNA-PK. We furthermore build upon his foundational work to provide recent insights into the structure of NHEJ synaptic complexes, an evolutionarily conserved and functionally important YRPD motif, and the role of DNA-PKcs and its phosphorylation in NHEJ. The combined results identify DNA-PKcs as a master regulator that is activated by its detection of two double-strand DNA ends for a cascade of phosphorylation events that provide specificity and efficiency in assembling the synaptic complex for NHEJ.
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88
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Chen X, Xu X, Chen Y, Cheung JC, Wang H, Jiang J, de Val N, Fox T, Gellert M, Yang W. Structure of an activated DNA-PK and its implications for NHEJ. Mol Cell 2020; 81:801-810.e3. [PMID: 33385326 DOI: 10.1016/j.molcel.2020.12.015] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/17/2020] [Accepted: 12/07/2020] [Indexed: 02/06/2023]
Abstract
DNA-dependent protein kinase (DNA-PK), like all phosphatidylinositol 3-kinase-related kinases (PIKKs), is composed of conserved FAT and kinase domains (FATKINs) along with solenoid structures made of HEAT repeats. These kinases are activated in response to cellular stress signals, but the mechanisms governing activation and regulation remain unresolved. For DNA-PK, all existing structures represent inactive states with resolution limited to 4.3 Å at best. Here, we report the cryoelectron microscopy (cryo-EM) structures of DNA-PKcs (DNA-PK catalytic subunit) bound to a DNA end or complexed with Ku70/80 and DNA in both inactive and activated forms at resolutions of 3.7 Å overall and 3.2 Å for FATKINs. These structures reveal the sequential transition of DNA-PK from inactive to activated forms. Most notably, activation of the kinase involves previously unknown stretching and twisting within individual solenoid segments and loosens DNA-end binding. This unprecedented structural plasticity of helical repeats may be a general regulatory mechanism of HEAT-repeat proteins.
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Affiliation(s)
- Xuemin Chen
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xiang Xu
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yun Chen
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Joyce C Cheung
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Huaibin Wang
- Laboratory of Cell and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jiansen Jiang
- Laboratory of Membrane Proteins and Structural Biology, NHLBI, National Institutes of Health, Bethesda, MD 20892, USA
| | - Natalia de Val
- Cancer Research Technology Program Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, MD 21701, USA
| | - Tara Fox
- Cancer Research Technology Program Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, MD 21701, USA
| | - Martin Gellert
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Wei Yang
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA.
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89
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Gago-Fuentes R, Oksenych V. Non-Homologous End Joining Factors XLF, PAXX and DNA-PKcs Maintain the Neural Stem and Progenitor Cell Population. Biomolecules 2020; 11:biom11010020. [PMID: 33379193 PMCID: PMC7823790 DOI: 10.3390/biom11010020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 12/19/2020] [Accepted: 12/23/2020] [Indexed: 12/26/2022] Open
Abstract
Non-homologous end-joining (NHEJ) is a major DNA repair pathway in mammalian cells that recognizes, processes and fixes DNA damage throughout the cell cycle and is specifically important for homeostasis of post-mitotic neurons and developing lymphocytes. Neuronal apoptosis increases in the mice lacking NHEJ factors Ku70 and Ku80. Inactivation of other NHEJ genes, either Xrcc4 or Lig4, leads to massive neuronal apoptosis in the central nervous system (CNS) that correlates with embryonic lethality in mice. Inactivation of either Paxx, Mri or Dna-pkcs NHEJ gene results in normal CNS development due to compensatory effects of Xlf. Combined inactivation of Xlf/Paxx, Xlf/Mri and Xlf/Dna-pkcs, however, results in late embryonic lethality and high levels of apoptosis in CNS. To determine the impact of NHEJ factors on the early stages of neurodevelopment, we isolated neural stem and progenitor cells from mouse embryos and investigated proliferation, self-renewal and differentiation capacity of these cells lacking either Xlf, Paxx, Dna-pkcs, Xlf/Paxx or Xlf/Dna-pkcs. We found that XRCC4-like factor (XLF), DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and paralogue of XRCC4 and XLF (PAXX) maintain the neural stem and progenitor cell populations and neurodevelopment in mammals, which is particularly evident in the double knockout models.
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Affiliation(s)
- Raquel Gago-Fuentes
- Department for Cancer Research and Molecular Medicine (IKOM), Norwegian University of Science and Technology, 7491 Trondheim, Norway;
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Valentyn Oksenych
- Department for Cancer Research and Molecular Medicine (IKOM), Norwegian University of Science and Technology, 7491 Trondheim, Norway;
- KG Jebsen Centre for B Cell Malignancies, Institute of Clinical Medicine, University of Oslo, 0316 Oslo, Norway
- Institute of Clinical Medicine, University of Oslo, 0318 Oslo, Norway
- Correspondence:
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90
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Eki R, She J, Parlak M, Benamar M, Du KP, Kumar P, Abbas T. A robust CRISPR-Cas9-based fluorescent reporter assay for the detection and quantification of DNA double-strand break repair. Nucleic Acids Res 2020; 48:e126. [PMID: 33068408 PMCID: PMC7708081 DOI: 10.1093/nar/gkaa897] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 09/25/2020] [Accepted: 09/30/2020] [Indexed: 12/30/2022] Open
Abstract
DNA double-strand breaks (DSBs) are highly cytotoxic lesions that can lead to chromosome rearrangements, genomic instability and cell death. Consequently, cells have evolved multiple mechanisms to efficiently repair DSBs to preserve genomic integrity. We have developed a DSB repair assay system, designated CDDR (CRISPR-Cas9-based Dual-fluorescent DSB Repair), that enables the detection and quantification of DSB repair outcomes in mammalian cells with high precision. CDDR is based on the introduction and subsequent resolution of one or two DSB(s) in an intrachromosomal fluorescent reporter following the expression of Cas9 and sgRNAs targeting the reporter. CDDR can discriminate between high-fidelity (HF) and error-prone non-homologous end-joining (NHEJ), as well as between proximal and distal NHEJ repair. Furthermore, CDDR can detect homology-directed repair (HDR) with high sensitivity. Using CDDR, we found HF-NHEJ to be strictly dependent on DNA Ligase IV, XRCC4 and XLF, members of the canonical branch of NHEJ pathway (c-NHEJ). Loss of these genes also stimulated HDR, and promoted error-prone distal end-joining. Deletion of the DNA repair kinase ATM, on the other hand, stimulated HF-NHEJ and suppressed HDR. These findings demonstrate the utility of CDDR in characterizing the effect of repair factors and in elucidating the balance between competing DSB repair pathways.
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Affiliation(s)
- Rebeka Eki
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA 22908, USA.,Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA.,Center for Cell Signaling, University of Virginia, Charlottesville, VA 22908, USA
| | - Jane She
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA 22908, USA
| | - Mahmut Parlak
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA 22908, USA
| | - Mouadh Benamar
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA 22908, USA.,Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA.,Center for Cell Signaling, University of Virginia, Charlottesville, VA 22908, USA
| | - Kang-Ping Du
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA 22908, USA
| | - Pankaj Kumar
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA
| | - Tarek Abbas
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA 22908, USA.,Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA.,Center for Cell Signaling, University of Virginia, Charlottesville, VA 22908, USA.,Cancer Center, University of Virginia, Charlottesville, VA 22908, USA
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91
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Du Y, Sun H, Lux F, Xie Y, Du L, Xu C, Zhang H, He N, Wang J, Liu Y, Leduc G, Doussineau T, Ji K, Wang Q, Lin Z, Wang Y, Liu Q, Tillement O. Radiosensitization Effect of AGuIX, a Gadolinium-Based Nanoparticle, in Nonsmall Cell Lung Cancer. ACS APPLIED MATERIALS & INTERFACES 2020; 12:56874-56885. [PMID: 33326207 DOI: 10.1021/acsami.0c16548] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Radiotherapy is the main treatment for cancer patients. A major concern in radiotherapy is the radiation resistance of some tumors, such as human nonsmall cell lung cancer. However, the radiation dose delivered to the tumors is often limited by the possibility of collateral damage to surrounding healthy tissues. A new and efficient gadolinium-based nanoparticle, AGuIX, has recently been developed for magnetic resonance imaging-guided radiotherapy and has been proven to act as an efficient radiosensitizer. The amplified radiation effects of AGuIX nanoparticles appear to be due to the emission of low-energy photoelectrons and Auger electron interactions. We demonstrated that AGuIX nanoparticles exacerbated radiation-induced DNA double-strand break damage and reduced DNA repair in the H1299 nonsmall cell lung cancer cell line. Furthermore, we observed a significant improvement in tumor cell damage and growth suppression, under radiation therapy, with the AGuIX nanoparticles in a H1299 mouse xenograft model. This study paves the way for research into the radiosensitization mechanism of AGuIX nanoparticles and provides a scientific basis for the use of AGuIX nanoparticles as radiosensitizing drugs.
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Affiliation(s)
- Yanan Du
- Institute of Radiation Medicine& Peking Union Medical College, Chinese Academy of Medical Sciences, 300192 Tianjin, China
- Tianjin Center for Disease Control and Prevention, 300011 Tianjin, China
| | - Hao Sun
- Institute of Radiation Medicine& Peking Union Medical College, Chinese Academy of Medical Sciences, 300192 Tianjin, China
| | - François Lux
- Institute Light and Mater, UMR5306, Lyon1 University-CNRS, Lyon University, 69100 Villeurbanne, France
- NH TherAguix, NH TherAguix SAS, 69100 Villeurbanne, France
| | - Yi Xie
- Institute of Modern Physics, Chinese Academy of Sciences, 730000 Lanzhou, China
| | - Liqing Du
- Institute of Radiation Medicine& Peking Union Medical College, Chinese Academy of Medical Sciences, 300192 Tianjin, China
| | - Chang Xu
- Institute of Radiation Medicine& Peking Union Medical College, Chinese Academy of Medical Sciences, 300192 Tianjin, China
| | - Hong Zhang
- Institute of Modern Physics, Chinese Academy of Sciences, 730000 Lanzhou, China
| | - Ningning He
- Institute of Radiation Medicine& Peking Union Medical College, Chinese Academy of Medical Sciences, 300192 Tianjin, China
| | - Jinhan Wang
- Institute of Radiation Medicine& Peking Union Medical College, Chinese Academy of Medical Sciences, 300192 Tianjin, China
| | - Yang Liu
- Institute of Radiation Medicine& Peking Union Medical College, Chinese Academy of Medical Sciences, 300192 Tianjin, China
| | | | | | - Kaihua Ji
- Institute of Radiation Medicine& Peking Union Medical College, Chinese Academy of Medical Sciences, 300192 Tianjin, China
| | - Qin Wang
- Institute of Radiation Medicine& Peking Union Medical College, Chinese Academy of Medical Sciences, 300192 Tianjin, China
| | - Zhenhua Lin
- NH TherAguix, NH TherAguix SAS, 69100 Villeurbanne, France
| | - Yan Wang
- Institute of Radiation Medicine& Peking Union Medical College, Chinese Academy of Medical Sciences, 300192 Tianjin, China
| | - Qiang Liu
- Institute of Radiation Medicine& Peking Union Medical College, Chinese Academy of Medical Sciences, 300192 Tianjin, China
| | - Olivier Tillement
- Institute Light and Mater, UMR5306, Lyon1 University-CNRS, Lyon University, 69100 Villeurbanne, France
- NH TherAguix, NH TherAguix SAS, 69100 Villeurbanne, France
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92
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Carney SM, Moreno AT, Piatt SC, Cisneros-Aguirre M, Lopezcolorado FW, Stark JM, Loparo JJ. XLF acts as a flexible connector during non-homologous end joining. eLife 2020; 9:e61920. [PMID: 33289484 PMCID: PMC7744095 DOI: 10.7554/elife.61920] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 12/07/2020] [Indexed: 01/01/2023] Open
Abstract
Non-homologous end joining (NHEJ) is the predominant pathway that repairs DNA double-strand breaks in vertebrates. During NHEJ DNA ends are held together by a multi-protein synaptic complex until they are ligated. Here, we use Xenopus laevis egg extract to investigate the role of the intrinsically disordered C-terminal tail of the XRCC4-like factor (XLF), a critical factor in end synapsis. We demonstrate that the XLF tail along with the Ku-binding motif (KBM) at the extreme C-terminus are required for end joining. Although the underlying sequence of the tail can be varied, a minimal tail length is required for NHEJ. Single-molecule FRET experiments that observe end synapsis in real-time show that this defect is due to a failure to closely align DNA ends. Our data supports a model in which a single C-terminal tail tethers XLF to Ku, while allowing XLF to form interactions with XRCC4 that enable synaptic complex formation.
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Affiliation(s)
- Sean M Carney
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical SchoolBostonUnited States
| | - Andrew T Moreno
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical SchoolBostonUnited States
| | - Sadie C Piatt
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical SchoolBostonUnited States
- Harvard Graduate Program in Biophysics, Harvard Medical SchoolBostonUnited States
| | - Metztli Cisneros-Aguirre
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of HopeDuarteUnited States
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of HopeDuarteUnited States
| | | | - Jeremy M Stark
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of HopeDuarteUnited States
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of HopeDuarteUnited States
| | - Joseph J Loparo
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical SchoolBostonUnited States
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93
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The molecular basis and disease relevance of non-homologous DNA end joining. Nat Rev Mol Cell Biol 2020; 21:765-781. [PMID: 33077885 DOI: 10.1038/s41580-020-00297-8] [Citation(s) in RCA: 201] [Impact Index Per Article: 50.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/08/2020] [Indexed: 12/26/2022]
Abstract
Non-homologous DNA end joining (NHEJ) is the predominant repair mechanism of any type of DNA double-strand break (DSB) during most of the cell cycle and is essential for the development of antigen receptors. Defects in NHEJ result in sensitivity to ionizing radiation and loss of lymphocytes. The most critical step of NHEJ is synapsis, or the juxtaposition of the two DNA ends of a DSB, because all subsequent steps rely on it. Recent findings show that, like the end processing step, synapsis can be achieved through several mechanisms. In this Review, we first discuss repair pathway choice between NHEJ and other DSB repair pathways. We then integrate recent insights into the mechanisms of NHEJ synapsis with updates on other steps of NHEJ, such as DNA end processing and ligation. Finally, we discuss NHEJ-related human diseases, including inherited disorders and neoplasia, which arise from rare failures at different NHEJ steps.
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94
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Castañeda-Zegarra S, Fernandez-Berrocal M, Tkachov M, Yao R, Upfold NLE, Oksenych V. Genetic interaction between the non-homologous end-joining factors during B and T lymphocyte development: In vivo mouse models. Scand J Immunol 2020; 92:e12936. [PMID: 32654175 DOI: 10.1111/sji.12936] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 06/07/2020] [Accepted: 07/06/2020] [Indexed: 12/16/2022]
Abstract
Non-homologous end joining (NHEJ) is the main DNA repair mechanism for the repair of double-strand breaks (DSBs) throughout the course of the cell cycle. DSBs are generated in developing B and T lymphocytes during V(D)J recombination to increase the repertoire of B and T cell receptors. DSBs are also generated during the class switch recombination (CSR) process in mature B lymphocytes, providing distinct effector functions of antibody heavy chain constant regions. Thus, NHEJ is important for both V(D)J recombination and CSR. NHEJ comprises core Ku70 and Ku80 subunits that form the Ku heterodimer, which binds DSBs and promotes the recruitment of accessory factors (e.g., DNA-PKcs, Artemis, PAXX, MRI) and downstream core factors (XLF, Lig4 and XRCC4). In recent decades, new NHEJ proteins have been reported, increasing complexity of this molecular pathway. Numerous in vivo mouse models have been generated and characterized to identify the interplay of NHEJ factors and their role in development of adaptive immune system. This review summarizes the currently available mouse models lacking one or several NHEJ factors, with a particular focus on early B cell development. We also underline genetic interactions and redundancy in the NHEJ pathway in mice.
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Affiliation(s)
- Sergio Castañeda-Zegarra
- Department of Clinical and Molecular Medicine (IKOM), Norwegian University of Science and Technology, Trondheim, Norway.,St. Olavs Hospital, Clinic of Medicine, Trondheim University Hospital, Trondheim, Norway
| | - Marion Fernandez-Berrocal
- Department of Clinical and Molecular Medicine (IKOM), Norwegian University of Science and Technology, Trondheim, Norway.,St. Olavs Hospital, Clinic of Medicine, Trondheim University Hospital, Trondheim, Norway.,Behavioural Neurobiology MS Program, Theodor-Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Germany
| | - Max Tkachov
- Department of Clinical and Molecular Medicine (IKOM), Norwegian University of Science and Technology, Trondheim, Norway.,St. Olavs Hospital, Clinic of Medicine, Trondheim University Hospital, Trondheim, Norway
| | - Rouan Yao
- Department of Clinical and Molecular Medicine (IKOM), Norwegian University of Science and Technology, Trondheim, Norway.,St. Olavs Hospital, Clinic of Medicine, Trondheim University Hospital, Trondheim, Norway
| | - Nikki Lyn Esnardo Upfold
- Department of Clinical and Molecular Medicine (IKOM), Norwegian University of Science and Technology, Trondheim, Norway.,St. Olavs Hospital, Clinic of Medicine, Trondheim University Hospital, Trondheim, Norway
| | - Valentyn Oksenych
- Department of Clinical and Molecular Medicine (IKOM), Norwegian University of Science and Technology, Trondheim, Norway.,St. Olavs Hospital, Clinic of Medicine, Trondheim University Hospital, Trondheim, Norway.,Department of Biosciences and Nutrition (BioNut), Karolinska Institutet, Huddinge, Sweden.,Department of Clinical Medicine, Faculty of Health Sciences, UiT-The Arctic University of Norway, Tromsø, Norway
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95
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Britton S, Chanut P, Delteil C, Barboule N, Frit P, Calsou P. ATM antagonizes NHEJ proteins assembly and DNA-ends synapsis at single-ended DNA double strand breaks. Nucleic Acids Res 2020; 48:9710-9723. [PMID: 32890395 PMCID: PMC7515714 DOI: 10.1093/nar/gkaa723] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 07/29/2020] [Accepted: 08/21/2020] [Indexed: 12/15/2022] Open
Abstract
Two DNA repair pathways operate at DNA double strand breaks (DSBs): non-homologous end-joining (NHEJ), that requires two adjacent DNA ends for ligation, and homologous recombination (HR), that resects one DNA strand for invasion of a homologous duplex. Faithful repair of replicative single-ended DSBs (seDSBs) is mediated by HR, due to the lack of a second DNA end for end-joining. ATM stimulates resection at such breaks through multiple mechanisms including CtIP phosphorylation, which also promotes removal of the DNA-ends sensor and NHEJ protein Ku. Here, using a new method for imaging the recruitment of the Ku partner DNA-PKcs at DSBs, we uncover an unanticipated role of ATM in removing DNA-PKcs from seDSBs in human cells. Phosphorylation of DNA-PKcs on the ABCDE cluster is necessary not only for DNA-PKcs clearance but also for the subsequent MRE11/CtIP-dependent release of Ku from these breaks. We propose that at seDSBs, ATM activity is necessary for the release of both Ku and DNA-PKcs components of the NHEJ apparatus, and thereby prevents subsequent aberrant interactions between seDSBs accompanied by DNA-PKcs autophosphorylation and detrimental commitment to Lig4-dependent end-joining.
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Affiliation(s)
- Sébastien Britton
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
| | - Pauline Chanut
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
| | - Christine Delteil
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
| | - Nadia Barboule
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
| | - Philippe Frit
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
| | - Patrick Calsou
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
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96
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Nej1 Interacts with Mre11 to Regulate Tethering and Dna2 Binding at DNA Double-Strand Breaks. Cell Rep 2020; 28:1564-1573.e3. [PMID: 31390569 PMCID: PMC6746346 DOI: 10.1016/j.celrep.2019.07.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 05/19/2019] [Accepted: 07/08/2019] [Indexed: 01/09/2023] Open
Abstract
Non-homologous end joining (NHEJ) and homologous recombination (HR) are the two major pathways of DNA double-strand break (DSB) repair and both are highly conserved from yeast to mammals. Nej1 has a role in DNA end-tethering at a DSB, and the Mre11/Rad50/Xrs2 (MRX) complex is important for its recruitment to the break. Nej1 and Dna2-Sgs1 interact with the C-terminal end of Mre11, which also includes the region where Rad50 binds. By characterizing the functionality of Nej1 in two rad50 mutants, which alter the structural features of MRX, we demonstrate that Nej1 inhibits the binding of Dna2 to Mre11 and Sgs1. Nej1 interactions with Mre11 promote tethering and inhibit hyper-resection, and when these events are compromised, large deletions develop at a DSB. The work indicates that Nej1 provides a layer of regulation to repair pathway choice and is consistent with its role in NHEJ. Mojumdar et al. characterize the role of Nej1 during double-strand break repair. They show Nej1 promotes non-homologous end joining (NHEJ) by tethering the broken DNA ends and by inhibiting hyper-resection mediated by Dna2-Sgs1.
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97
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The Determinant of DNA Repair Pathway Choices in Ionising Radiation-Induced DNA Double-Strand Breaks. BIOMED RESEARCH INTERNATIONAL 2020; 2020:4834965. [PMID: 32908893 PMCID: PMC7468606 DOI: 10.1155/2020/4834965] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 07/13/2020] [Accepted: 07/30/2020] [Indexed: 02/07/2023]
Abstract
Ionising radiation- (IR-) induced DNA double-strand breaks (DSBs) are considered to be the deleterious DNA lesions that pose a serious threat to genomic stability. The major DNA repair pathways, including classical nonhomologous end joining, homologous recombination, single-strand annealing, and alternative end joining, play critical roles in countering and eliciting IR-induced DSBs to ensure genome integrity. If the IR-induced DNA DSBs are not repaired correctly, the residual or incorrectly repaired DSBs can result in genomic instability that is associated with certain human diseases. Although many efforts have been made in investigating the major mechanisms of IR-induced DNA DSB repair, it is still unclear what determines the choices of IR-induced DNA DSB repair pathways. In this review, we discuss how the mechanisms of IR-induced DSB repair pathway choices can operate in irradiated cells. We first briefly describe the main mechanisms of the major DNA DSB repair pathways and the related key repair proteins. Based on our understanding of the characteristics of IR-induced DNA DSBs and the regulatory mechanisms of DSB repair pathways in irradiated cells and recent advances in this field, We then highlight the main factors and associated challenges to determine the IR-induced DSB repair pathway choices. We conclude that the type and distribution of IR-induced DSBs, chromatin state, DNA-end structure, and DNA-end resection are the main determinants of the choice of the IR-induced DNA DSB repair pathway.
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98
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Zhao L, Bao C, Shang Y, He X, Ma C, Lei X, Mi D, Sun Y. The Determinant of DNA Repair Pathway Choices in Ionising Radiation-Induced DNA Double-Strand Breaks. BIOMED RESEARCH INTERNATIONAL 2020. [DOI: doi.org/10.1155/2020/4834965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Ionising radiation- (IR-) induced DNA double-strand breaks (DSBs) are considered to be the deleterious DNA lesions that pose a serious threat to genomic stability. The major DNA repair pathways, including classical nonhomologous end joining, homologous recombination, single-strand annealing, and alternative end joining, play critical roles in countering and eliciting IR-induced DSBs to ensure genome integrity. If the IR-induced DNA DSBs are not repaired correctly, the residual or incorrectly repaired DSBs can result in genomic instability that is associated with certain human diseases. Although many efforts have been made in investigating the major mechanisms of IR-induced DNA DSB repair, it is still unclear what determines the choices of IR-induced DNA DSB repair pathways. In this review, we discuss how the mechanisms of IR-induced DSB repair pathway choices can operate in irradiated cells. We first briefly describe the main mechanisms of the major DNA DSB repair pathways and the related key repair proteins. Based on our understanding of the characteristics of IR-induced DNA DSBs and the regulatory mechanisms of DSB repair pathways in irradiated cells and recent advances in this field, We then highlight the main factors and associated challenges to determine the IR-induced DSB repair pathway choices. We conclude that the type and distribution of IR-induced DSBs, chromatin state, DNA-end structure, and DNA-end resection are the main determinants of the choice of the IR-induced DNA DSB repair pathway.
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Affiliation(s)
- Lei Zhao
- Institute of Environmental Systems Biology, College of Environmental Science and Engineering, Dalian Maritime University, Dalian, 116026 Liaoning, China
| | - Chengyu Bao
- Institute of Environmental Systems Biology, College of Environmental Science and Engineering, Dalian Maritime University, Dalian, 116026 Liaoning, China
| | - Yuxuan Shang
- Institute of Environmental Systems Biology, College of Environmental Science and Engineering, Dalian Maritime University, Dalian, 116026 Liaoning, China
| | - Xinye He
- Institute of Environmental Systems Biology, College of Environmental Science and Engineering, Dalian Maritime University, Dalian, 116026 Liaoning, China
| | - Chiyuan Ma
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Xiaohua Lei
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Dong Mi
- College of Science, Dalian Maritime University, Dalian, Liaoning, China
| | - Yeqing Sun
- Institute of Environmental Systems Biology, College of Environmental Science and Engineering, Dalian Maritime University, Dalian, 116026 Liaoning, China
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99
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Zhao B, Watanabe G, Lieber MR. Polymerase μ in non-homologous DNA end joining: importance of the order of arrival at a double-strand break in a purified system. Nucleic Acids Res 2020; 48:3605-3618. [PMID: 32052035 PMCID: PMC7144918 DOI: 10.1093/nar/gkaa094] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/14/2020] [Accepted: 02/04/2020] [Indexed: 01/07/2023] Open
Abstract
During non-homologous DNA end joining (NHEJ), bringing two broken dsDNA ends into proximity is an essential prerequisite for ligation by XRCC4:Ligase IV (X4L4). This physical juxtaposition of DNA ends is called NHEJ synapsis. In addition to the key NHEJ synapsis proteins, Ku, X4L4, and XLF, it has been suggested that DNA polymerase mu (pol μ) may also align two dsDNA ends into close proximity for synthesis. Here, we directly observe the NHEJ synapsis by pol μ using a single molecule FRET (smFRET) assay where we can measure the duration of the synapsis. The results show that pol μ alone can mediate efficient NHEJ synapsis of 3′ overhangs that have at least 1 nt microhomology. The abundant Ku protein in cells limits the accessibility of pol μ to DNA ends with overhangs. But X4L4 can largely reverse the Ku inhibition, perhaps by pushing the Ku inward to expose the overhang for NHEJ synapsis. Based on these studies, the mechanistic flexibility known to exist at other steps of NHEJ is now also apparent for the NHEJ synapsis step.
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Affiliation(s)
- Bailin Zhao
- Department of Pathology, Department of Biochemistry & Molecular Biology, Department of Molecular Microbiology & Immunology, and Section of Computational & Molecular Biology, USC Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, 1441 Eastlake Ave, Rm. 5428, Los Angeles, CA 90089, USA
| | - Go Watanabe
- Department of Pathology, Department of Biochemistry & Molecular Biology, Department of Molecular Microbiology & Immunology, and Section of Computational & Molecular Biology, USC Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, 1441 Eastlake Ave, Rm. 5428, Los Angeles, CA 90089, USA
| | - Michael R Lieber
- Department of Pathology, Department of Biochemistry & Molecular Biology, Department of Molecular Microbiology & Immunology, and Section of Computational & Molecular Biology, USC Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, 1441 Eastlake Ave, Rm. 5428, Los Angeles, CA 90089, USA
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100
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Structural mechanism of DNA-end synapsis in the non-homologous end joining pathway for repairing double-strand breaks: bridge over troubled ends. Biochem Soc Trans 2020; 47:1609-1619. [PMID: 31829407 DOI: 10.1042/bst20180518] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 11/25/2019] [Accepted: 11/27/2019] [Indexed: 12/18/2022]
Abstract
Non-homologous end joining (NHEJ) is a major repair pathway for DNA double-strand breaks (DSBs), which is the most toxic DNA damage in cells. Unrepaired DSBs can cause genome instability, tumorigenesis or cell death. DNA end synapsis is the first and probably the most important step of the NHEJ pathway, aiming to bring two broken DNA ends close together and provide structural stability for end processing and ligation. This process is mediated through a group of NHEJ proteins forming higher-order complexes, to recognise and bridge two DNA ends. Spatial and temporal understanding of the structural mechanism of DNA-end synapsis has been largely advanced through recent structural and single-molecule studies of NHEJ proteins. This review focuses on core NHEJ proteins that mediate DNA end synapsis through their unique structures and interaction properties, as well as how they play roles as anchor and linker proteins during the process of 'bridge over troubled ends'.
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