1
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Melia E, Parsons J. DNA damage and repair dependencies of ionising radiation modalities. Biosci Rep 2023; 43:BSR20222586. [PMID: 37695845 PMCID: PMC10548165 DOI: 10.1042/bsr20222586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 08/18/2023] [Accepted: 09/11/2023] [Indexed: 09/13/2023] Open
Abstract
Radiotherapy is utilised in the treatment of ∼50% of all human cancers, which predominantly employs photon radiation. However, particle radiotherapy elicits significant benefits over conventional photons due to more precise dose deposition and increased linear energy transfer (LET) that generates an enhanced therapeutic response. Specifically, proton beam therapy (PBT) and carbon ion radiotherapy (CIRT) are characterised by a Bragg peak, which generates a low entrance radiation dose, with the majority of the energy deposition being defined within a small region which can be specifically targeted to the tumour, followed by a low exit dose. PBT is deemed relatively low-LET whereas CIRT is more densely ionising and therefore high LET. Despite the radiotherapy type, tumour cell killing relies heavily on the introduction of DNA damage that overwhelms the repair capacity of the tumour cells. It is known that DNA damage complexity increases with LET that leads to enhanced biological effectiveness, although the specific DNA repair pathways that are activated following the different radiation sources is unclear. This knowledge is required to determine whether specific proteins and enzymes within these pathways can be targeted to further increase the efficacy of the radiation. In this review, we provide an overview of the different radiation modalities and the DNA repair pathways that are responsive to these. We also provide up-to-date knowledge of studies examining the impact of LET and DNA damage complexity on DNA repair pathway choice, followed by evidence on how enzymes within these pathways could potentially be therapeutically exploited to further increase tumour radiosensitivity, and therefore radiotherapy efficacy.
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Affiliation(s)
- Emma Melia
- Institute of Cancer and Genomic Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K
| | - Jason L. Parsons
- Institute of Cancer and Genomic Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K
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2
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Vogt A, He Y. Structure and mechanism in non-homologous end joining. DNA Repair (Amst) 2023; 130:103547. [PMID: 37556875 PMCID: PMC10528545 DOI: 10.1016/j.dnarep.2023.103547] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 08/11/2023]
Abstract
DNA double-stranded breaks (DSBs) are a particularly challenging form of DNA damage to repair because the damaged DNA must not only undergo the chemical reactions responsible for returning it to its original state, but, additionally, the two free ends can become physically separated in the nucleus and must be bridged prior to repair. In nonhomologous end joining (NHEJ), one of the major pathways of DSB repair, repair is carried out by a number of repair factors capable of binding to and directly joining DNA ends. It has been unclear how these processes are carried out at a molecular level, owing in part to the lack of structural evidence describing the coordination of the NHEJ factors with each other and a DNA substrate. Advances in cryo-Electron Microscopy (cryo-EM), allowing for the structural characterization of large protein complexes that would be intractable using other techniques, have led to the visualization several key steps of the NHEJ process, which support a model of sequential assembly of repair factors at the DSB, followed by end-bridging mediated by protein-protein complexes and transition to full synapsis. Here we examine the structural evidence for these models, devoting particular attention to recent work identifying a new NHEJ intermediate state and incorporating new NHEJ factors into the general mechanism. We also discuss the evolving understanding of end-bridging mechanisms in NHEJ and DNA-PKcs's role in mediating DSB repair.
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Affiliation(s)
- Alex Vogt
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA; Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, USA
| | - Yuan He
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA; Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, USA; Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, USA; Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Northwestern University, Chicago, USA.
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3
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Russell ML, Simon N, Bradley P, Matsen FA. Statistical inference reveals the role of length, GC content, and local sequence in V(D)J nucleotide trimming. eLife 2023; 12:e85145. [PMID: 37227256 PMCID: PMC10212571 DOI: 10.7554/elife.85145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 04/11/2023] [Indexed: 05/26/2023] Open
Abstract
To appropriately defend against a wide array of pathogens, humans somatically generate highly diverse repertoires of B cell and T cell receptors (BCRs and TCRs) through a random process called V(D)J recombination. Receptor diversity is achieved during this process through both the combinatorial assembly of V(D)J-genes and the junctional deletion and insertion of nucleotides. While the Artemis protein is often regarded as the main nuclease involved in V(D)J recombination, the exact mechanism of nucleotide trimming is not understood. Using a previously published TCRβ repertoire sequencing data set, we have designed a flexible probabilistic model of nucleotide trimming that allows us to explore various mechanistically interpretable sequence-level features. We show that local sequence context, length, and GC nucleotide content in both directions of the wider sequence, together, can most accurately predict the trimming probabilities of a given V-gene sequence. Because GC nucleotide content is predictive of sequence-breathing, this model provides quantitative statistical evidence regarding the extent to which double-stranded DNA may need to be able to breathe for trimming to occur. We also see evidence of a sequence motif that appears to get preferentially trimmed, independent of GC-content-related effects. Further, we find that the inferred coefficients from this model provide accurate prediction for V- and J-gene sequences from other adaptive immune receptor loci. These results refine our understanding of how the Artemis nuclease may function to trim nucleotides during V(D)J recombination and provide another step toward understanding how V(D)J recombination generates diverse receptors and supports a powerful, unique immune response in healthy humans.
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Affiliation(s)
- Magdalena L Russell
- Computational Biology Program, Fred Hutchinson Cancer CenterSeattleUnited States
- Molecular and Cellular Biology Program, University of WashingtonSeattleUnited States
| | - Noah Simon
- Department of Biostatistics, University of WashingtonSeattleUnited States
| | - Philip Bradley
- Computational Biology Program, Fred Hutchinson Cancer CenterSeattleUnited States
- Institute for Protein Design, Department of Biochemistry, University of WashingtonSeattleUnited States
| | - Frederick A Matsen
- Computational Biology Program, Fred Hutchinson Cancer CenterSeattleUnited States
- Department of Genome Sciences, University of WashingtonSeattleUnited States
- Department of Statistics, University of WashingtonSeattleUnited States
- Howard Hughes Medical InstituteSeattleUnited States
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4
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Watanabe G, Lieber MR. Dynamics of the Artemis and DNA-PKcs Complex in the Repair of Double-Strand Breaks. J Mol Biol 2022; 434:167858. [PMID: 36270581 PMCID: PMC9940633 DOI: 10.1016/j.jmb.2022.167858] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/11/2022] [Accepted: 10/11/2022] [Indexed: 11/05/2022]
Abstract
Pathologic chromosome breaks occur in human dividing cells ∼10 times per day, and physiologic breaks occur in each lymphoid cell many additional times per day. Nonhomologous DNA end joining (NHEJ) is the major pathway for the repair of all of these double-strand breaks (DSBs) during most of the cell cycle. Nearly all broken DNA ends require trimming before they can be suitable for joining by ligation. Artemis is the major nuclease for this purpose. Artemis is tightly regulated by one of the largest protein kinases, which tethers Artemis to its surface. This kinase is called DNA-dependent protein kinase catalytic subunit (or DNA-PKcs) because it is only active when it encounters a broken DNA end. With this activation, DNA-PKcs permits the Artemis catalytic domain to enter a large cavity in the center of DNA-PKcs. Given this remarkably tight supervision of Artemis by DNA-PKcs, it is an appropriate time to ask what we know about the Artemis:DNA-PKcs complex, as we integrate recent structural information with the biochemistry of the complex and how this relates to other NHEJ proteins and to V(D)J recombination in the immune system.
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Affiliation(s)
- Go Watanabe
- Department of Pathology, Department of Biochemistry & Molecular Biology, Department of Molecular Microbiology & Immunology, and Section of Molecular & Computational 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 Molecular & Computational 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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5
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El Nachef L, Berthel E, Ferlazzo ML, Le Reun E, Al-Choboq J, Restier-Verlet J, Granzotto A, Sonzogni L, Bourguignon M, Foray N. Cancer and Radiosensitivity Syndromes: Is Impaired Nuclear ATM Kinase Activity the Primum Movens? Cancers (Basel) 2022; 14:cancers14246141. [PMID: 36551628 PMCID: PMC9776478 DOI: 10.3390/cancers14246141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 12/01/2022] [Accepted: 12/09/2022] [Indexed: 12/15/2022] Open
Abstract
There are a number of genetic syndromes associated with both high cancer risk and clinical radiosensitivity. However, the link between these two notions remains unknown. Particularly, some cancer syndromes are caused by mutations in genes involved in DNA damage signaling and repair. How are the DNA sequence errors propagated and amplified to cause cell transformation? Conversely, some cancer syndromes are caused by mutations in genes involved in cell cycle checkpoint control. How is misrepaired DNA damage produced? Lastly, certain genes, considered as tumor suppressors, are not involved in DNA damage signaling and repair or in cell cycle checkpoint control. The mechanistic model based on radiation-induced nucleoshuttling of the ATM kinase (RIANS), a major actor of the response to ionizing radiation, may help in providing a unified explanation of the link between cancer proneness and radiosensitivity. In the frame of this model, a given protein may ensure its own specific function but may also play additional biological role(s) as an ATM phosphorylation substrate in cytoplasm. It appears that the mutated proteins that cause the major cancer and radiosensitivity syndromes are all ATM phosphorylation substrates, and they generally localize in the cytoplasm when mutated. The relevance of the RIANS model is discussed by considering different categories of the cancer syndromes.
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Affiliation(s)
- Laura El Nachef
- Inserm, U1296 Unit, Radiation: Defense, Health and Environment, Centre Léon-Bérard, 69008 Lyon, France
| | - Elise Berthel
- Inserm, U1296 Unit, Radiation: Defense, Health and Environment, Centre Léon-Bérard, 69008 Lyon, France
| | - Mélanie L. Ferlazzo
- Inserm, U1296 Unit, Radiation: Defense, Health and Environment, Centre Léon-Bérard, 69008 Lyon, France
| | - Eymeric Le Reun
- Inserm, U1296 Unit, Radiation: Defense, Health and Environment, Centre Léon-Bérard, 69008 Lyon, France
| | - Joelle Al-Choboq
- Inserm, U1296 Unit, Radiation: Defense, Health and Environment, Centre Léon-Bérard, 69008 Lyon, France
| | - Juliette Restier-Verlet
- Inserm, U1296 Unit, Radiation: Defense, Health and Environment, Centre Léon-Bérard, 69008 Lyon, France
| | - Adeline Granzotto
- Inserm, U1296 Unit, Radiation: Defense, Health and Environment, Centre Léon-Bérard, 69008 Lyon, France
| | - Laurène Sonzogni
- Inserm, U1296 Unit, Radiation: Defense, Health and Environment, Centre Léon-Bérard, 69008 Lyon, France
| | - Michel Bourguignon
- Inserm, U1296 Unit, Radiation: Defense, Health and Environment, Centre Léon-Bérard, 69008 Lyon, France
- Department of Biophysics and Nuclear Medicine, Université Paris Saclay (UVSQ), 78035 Versailles, France
| | - Nicolas Foray
- Inserm, U1296 Unit, Radiation: Defense, Health and Environment, Centre Léon-Bérard, 69008 Lyon, France
- Correspondence: ; Tel.: +33-04-7878-2828
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6
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Talibova G, Bilmez Y, Ozturk S. DNA double-strand break repair in male germ cells during spermatogenesis and its association with male infertility development. DNA Repair (Amst) 2022; 118:103386. [DOI: 10.1016/j.dnarep.2022.103386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 08/01/2022] [Accepted: 08/03/2022] [Indexed: 11/16/2022]
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7
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Kelm JM, Samarbakhsh A, Pillai A, VanderVere-Carozza PS, Aruri H, Pandey DS, Pawelczak KS, Turchi JJ, Gavande NS. Recent Advances in the Development of Non-PIKKs Targeting Small Molecule Inhibitors of DNA Double-Strand Break Repair. Front Oncol 2022; 12:850883. [PMID: 35463312 PMCID: PMC9020266 DOI: 10.3389/fonc.2022.850883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Accepted: 02/22/2022] [Indexed: 01/09/2023] Open
Abstract
The vast majority of cancer patients receive DNA-damaging drugs or ionizing radiation (IR) during their course of treatment, yet the efficacy of these therapies is tempered by DNA repair and DNA damage response (DDR) pathways. Aberrations in DNA repair and the DDR are observed in many cancer subtypes and can promote de novo carcinogenesis, genomic instability, and ensuing resistance to current cancer therapy. Additionally, stalled or collapsed DNA replication forks present a unique challenge to the double-strand DNA break (DSB) repair system. Of the various inducible DNA lesions, DSBs are the most lethal and thus desirable in the setting of cancer treatment. In mammalian cells, DSBs are typically repaired by the error prone non-homologous end joining pathway (NHEJ) or the high-fidelity homology directed repair (HDR) pathway. Targeting DSB repair pathways using small molecular inhibitors offers a promising mechanism to synergize DNA-damaging drugs and IR while selective inhibition of the NHEJ pathway can induce synthetic lethality in HDR-deficient cancer subtypes. Selective inhibitors of the NHEJ pathway and alternative DSB-repair pathways may also see future use in precision genome editing to direct repair of resulting DSBs created by the HDR pathway. In this review, we highlight the recent advances in the development of inhibitors of the non-phosphatidylinositol 3-kinase-related kinases (non-PIKKs) members of the NHEJ, HDR and minor backup SSA and alt-NHEJ DSB-repair pathways. The inhibitors described within this review target the non-PIKKs mediators of DSB repair including Ku70/80, Artemis, DNA Ligase IV, XRCC4, MRN complex, RPA, RAD51, RAD52, ERCC1-XPF, helicases, and DNA polymerase θ. While the DDR PIKKs remain intensely pursued as therapeutic targets, small molecule inhibition of non-PIKKs represents an emerging opportunity in drug discovery that offers considerable potential to impact cancer treatment.
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Affiliation(s)
- Jeremy M. Kelm
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, United States
| | - Amirreza Samarbakhsh
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, United States
| | - Athira Pillai
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, United States
| | | | - Hariprasad Aruri
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, United States
| | - Deepti S. Pandey
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, United States
| | | | - John J. Turchi
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, United States,NERx Biosciences, Indianapolis, IN, United States,Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Navnath S. Gavande
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, United States,Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, United States,*Correspondence: Navnath S. Gavande, ; orcid.org/0000-0002-2413-0235
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8
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Russell ML, Souquette A, Levine DM, Schattgen SA, Allen EK, Kuan G, Simon N, Balmaseda A, Gordon A, Thomas PG, Matsen FA, Bradley P. Combining genotypes and T cell receptor distributions to infer genetic loci determining V(D)J recombination probabilities. eLife 2022; 11:73475. [PMID: 35315770 PMCID: PMC8940181 DOI: 10.7554/elife.73475] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 01/17/2022] [Indexed: 12/12/2022] Open
Abstract
Every T cell receptor (TCR) repertoire is shaped by a complex probabilistic tangle of genetically determined biases and immune exposures. T cells combine a random V(D)J recombination process with a selection process to generate highly diverse and functional TCRs. The extent to which an individual’s genetic background is associated with their resulting TCR repertoire diversity has yet to be fully explored. Using a previously published repertoire sequencing dataset paired with high-resolution genome-wide genotyping from a large human cohort, we infer specific genetic loci associated with V(D)J recombination probabilities using genome-wide association inference. We show that V(D)J gene usage profiles are associated with variation in the TCRB locus and, specifically for the functional TCR repertoire, variation in the major histocompatibility complex locus. Further, we identify specific variations in the genes encoding the Artemis protein and the TdT protein to be associated with biasing junctional nucleotide deletion and N-insertion, respectively. These results refine our understanding of genetically-determined TCR repertoire biases by confirming and extending previous studies on the genetic determinants of V(D)J gene usage and providing the first examples of trans genetic variants which are associated with modifying junctional diversity. Together, these insights lay the groundwork for further explorations into how immune responses vary between individuals.
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Affiliation(s)
- Magdalena L Russell
- Computational Biology Program, Fred Hutch Cancer Research Center
- Molecular and Cellular Biology Program, University of Washington
| | - Aisha Souquette
- Department of Immunology, St. Jude Children’s Research Hospital
- Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Science Center
| | | | | | | | - Guillermina Kuan
- Centro Nacional de Diagnóstico y Referencia, Ministry of Health
- Sustainable Sciences Institute
| | - Noah Simon
- Department of Biostatistics, University of Washington
| | - Angel Balmaseda
- Centro Nacional de Diagnóstico y Referencia, Ministry of Health
- Sustainable Sciences Institute
| | | | - Paul G Thomas
- Department of Immunology, St. Jude Children’s Research Hospital
| | - Frederick A Matsen
- Computational Biology Program, Fred Hutch Cancer Research Center
- Department of Genome Sciences, University of Washington
- Department of Statistics, University of Washington
- Howard Hughes Medical Institute
| | - Philip Bradley
- Computational Biology Program, Fred Hutch Cancer Research Center
- Institute for Protein Design, Department of Biochemistry, University of Washington
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9
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Mir SM, Aliarab A, Goodarzi G, Shirzad M, Jafari SM, Qujeq D, Samavarchi Tehrani S, Asadi J. Melatonin: A smart molecule in the DNA repair system. Cell Biochem Funct 2021; 40:4-16. [PMID: 34672014 DOI: 10.1002/cbf.3672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 09/03/2021] [Accepted: 10/02/2021] [Indexed: 12/14/2022]
Abstract
DNA repair is an important pathway for the protection of DNA molecules from destruction. DNA damage can be produced by oxidative reactive nitrogen or oxygen species, irritation, alkylating agents, depurination and depyrimidination; in this regard, DNA repair pathways can neutralize the negative effects of these factors. Melatonin is a hormone secreted from the pineal gland with an antioxidant effect by binding to oxidative factors. In addition, the effect of melatonin on DNA repair pathways has been proven by the literature. DNA repair is carried out by several mechanisms, of which homologous recombination repair (HRR) and non-homologous end-joining (NHEJ) are of great importance. Because of the importance of DNA repair in DNA integrity and the anticancer effect of this pathway, we presented the effect of melatonin on DNA repair factors regarding previous studies conducted in this area.
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Affiliation(s)
- Seyed Mostafa Mir
- Metabolic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran
| | - Azadeh Aliarab
- Department of Clinical Biochemistry, School of Medicine, Tarbiat Modares University, Tehran, Iran
| | - Golnaz Goodarzi
- Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.,Student Scientific Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Moein Shirzad
- Department of Clinical Biochemistry, Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran.,Cellular and Molecular Biology Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
| | - Seyyed Mehdi Jafari
- Metabolic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran
| | - Durdi Qujeq
- Department of Clinical Biochemistry, Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran.,Cellular and Molecular Biology Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
| | - Sadra Samavarchi Tehrani
- Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.,Student Scientific Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Jahanbakhsh Asadi
- Metabolic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran
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10
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Yosaatmadja Y, Baddock H, Newman J, Bielinski M, Gavard A, Mukhopadhyay SMM, Dannerfjord A, Schofield C, McHugh P, Gileadi O. Structural and mechanistic insights into the Artemis endonuclease and strategies for its inhibition. Nucleic Acids Res 2021; 49:9310-9326. [PMID: 34387696 PMCID: PMC8450076 DOI: 10.1093/nar/gkab693] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 07/20/2021] [Accepted: 08/11/2021] [Indexed: 12/23/2022] Open
Abstract
Artemis (SNM1C/DCLRE1C) is an endonuclease that plays a key role in development of B- and T-lymphocytes and in dsDNA break repair by non-homologous end-joining (NHEJ). Artemis is phosphorylated by DNA-PKcs and acts to open DNA hairpin intermediates generated during V(D)J and class-switch recombination. Artemis deficiency leads to congenital radiosensitive severe acquired immune deficiency (RS-SCID). Artemis belongs to a superfamily of nucleases containing metallo-β-lactamase (MBL) and β-CASP (CPSF-Artemis-SNM1-Pso2) domains. We present crystal structures of the catalytic domain of wildtype and variant forms of Artemis, including one causing RS-SCID Omenn syndrome. The catalytic domain of the Artemis has similar endonuclease activity to the phosphorylated full-length protein. Our structures help explain the predominantly endonucleolytic activity of Artemis, which contrasts with the predominantly exonuclease activity of the closely related SNM1A and SNM1B MBL fold nucleases. The structures reveal a second metal binding site in its β-CASP domain unique to Artemis, which is amenable to inhibition by compounds including ebselen. By combining our structural data with that from a recently reported Artemis structure, we were able model the interaction of Artemis with DNA substrates. The structures, including one of Artemis with the cephalosporin ceftriaxone, will help enable the rational development of selective SNM1 nuclease inhibitors.
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Affiliation(s)
- Yuliana Yosaatmadja
- Centre for Medicines Discovery, University of Oxford, ORCRB, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Hannah T Baddock
- Department of Oncology, MRC-Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Joseph A Newman
- Centre for Medicines Discovery, University of Oxford, ORCRB, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Marcin Bielinski
- The Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK
| | - Angeline E Gavard
- Centre for Medicines Discovery, University of Oxford, ORCRB, Roosevelt Drive, Oxford OX3 7DQ, UK
| | | | - Adam A Dannerfjord
- Centre for Medicines Discovery, University of Oxford, ORCRB, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Christopher J Schofield
- The Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK
| | - Peter J McHugh
- Department of Oncology, MRC-Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Opher Gileadi
- Centre for Medicines Discovery, University of Oxford, ORCRB, Roosevelt Drive, Oxford OX3 7DQ, UK
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11
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Hawkins CJ, Miles MA. Mutagenic Consequences of Sublethal Cell Death Signaling. Int J Mol Sci 2021; 22:ijms22116144. [PMID: 34200309 PMCID: PMC8201051 DOI: 10.3390/ijms22116144] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/03/2021] [Accepted: 06/05/2021] [Indexed: 02/06/2023] Open
Abstract
Many human cancers exhibit defects in key DNA damage response elements that can render tumors insensitive to the cell death-promoting properties of DNA-damaging therapies. Using agents that directly induce apoptosis by targeting apoptotic components, rather than relying on DNA damage to indirectly stimulate apoptosis of cancer cells, may overcome classical blocks exploited by cancer cells to evade apoptotic cell death. However, there is increasing evidence that cells surviving sublethal exposure to classical apoptotic signaling may recover with newly acquired genomic changes which may have oncogenic potential, and so could theoretically spur the development of subsequent cancers in cured patients. Encouragingly, cells surviving sublethal necroptotic signaling did not acquire mutations, suggesting that necroptosis-inducing anti-cancer drugs may be less likely to trigger therapy-related cancers. We are yet to develop effective direct inducers of other cell death pathways, and as such, data regarding the consequences of cells surviving sublethal stimulation of those pathways are still emerging. This review details the currently known mutagenic consequences of cells surviving different cell death signaling pathways, with implications for potential oncogenic transformation. Understanding the mechanisms of mutagenesis associated (or not) with various cell death pathways will guide us in the development of future therapeutics to minimize therapy-related side effects associated with DNA damage.
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Affiliation(s)
- Christine J. Hawkins
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC 3086, Australia;
| | - Mark A. Miles
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC 3086, Australia;
- School of Health and Biomedical Sciences, RMIT University, Bundoora, VIC 3083, Australia
- Correspondence:
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12
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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: 17] [Impact Index Per Article: 5.7] [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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13
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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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14
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Mastio J, Saeed MB, Wurzer H, Krecke M, Westerberg LS, Thomas C. Higher Incidence of B Cell Malignancies in Primary Immunodeficiencies: A Combination of Intrinsic Genomic Instability and Exocytosis Defects at the Immunological Synapse. Front Immunol 2020; 11:581119. [PMID: 33240268 PMCID: PMC7680899 DOI: 10.3389/fimmu.2020.581119] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/09/2020] [Indexed: 12/11/2022] Open
Abstract
Congenital defects of the immune system called primary immunodeficiency disorders (PID) describe a group of diseases characterized by a decrease, an absence, or a malfunction of at least one part of the immune system. As a result, PID patients are more prone to develop life-threatening complications, including cancer. PID currently include over 400 different disorders, however, the variety of PID-related cancers is narrow. We discuss here reasons for this clinical phenotype. Namely, PID can lead to cell intrinsic failure to control cell transformation, failure to activate tumor surveillance by cytotoxic cells or both. As the most frequent tumors seen among PID patients stem from faulty lymphocyte development leading to leukemia and lymphoma, we focus on the extensive genomic alterations needed to create the vast diversity of B and T lymphocytes with potential to recognize any pathogen and why defects in these processes lead to malignancies in the immunodeficient environment of PID patients. In the second part of the review, we discuss PID affecting tumor surveillance and especially membrane trafficking defects caused by altered exocytosis and regulation of the actin cytoskeleton. As an impairment of these membrane trafficking pathways often results in dysfunctional effector immune cells, tumor cell immune evasion is elevated in PID. By considering new anti-cancer treatment concepts, such as transfer of genetically engineered immune cells, restoration of anti-tumor immunity in PID patients could be an approach to complement standard therapies.
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Affiliation(s)
- Jérôme Mastio
- Department of Oncology, Cytoskeleton and Cancer Progression, Luxembourg Institute of Health, Luxembourg City, Luxembourg
| | - Mezida B Saeed
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Hannah Wurzer
- Department of Oncology, Cytoskeleton and Cancer Progression, Luxembourg Institute of Health, Luxembourg City, Luxembourg
| | - Max Krecke
- Department of Oncology, Cytoskeleton and Cancer Progression, Luxembourg Institute of Health, Luxembourg City, Luxembourg
| | - Lisa S Westerberg
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Clément Thomas
- Department of Oncology, Cytoskeleton and Cancer Progression, Luxembourg Institute of Health, Luxembourg City, Luxembourg
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15
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Meek K. Activation of DNA-PK by hairpinned DNA ends reveals a stepwise mechanism of kinase activation. Nucleic Acids Res 2020; 48:9098-9108. [PMID: 32716029 PMCID: PMC7498359 DOI: 10.1093/nar/gkaa614] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 07/08/2020] [Accepted: 07/14/2020] [Indexed: 12/12/2022] Open
Abstract
As its name implies, the DNA dependent protein kinase (DNA-PK) requires DNA double-stranded ends for enzymatic activation. Here, I demonstrate that hairpinned DNA ends are ineffective for activating the kinase toward many of its well-studied substrates (p53, XRCC4, XLF, HSP90). However, hairpinned DNA ends robustly stimulate certain DNA-PK autophosphorylations. Specifically, autophosphorylation sites within the ABCDE cluster are robustly phosphorylated when DNA-PK is activated by hairpinned DNA ends. Of note, phosphorylation of the ABCDE sites is requisite for activation of the Artemis nuclease that associates with DNA-PK to mediate hairpin opening. This finding suggests a multi-step mechanism of kinase activation. Finally, I find that all non-homologous end joining (NHEJ) defective cells (whether deficient in components of the DNA-PK complex or components of the ligase complex) are similarly deficient in joining DNA double-stranded breaks (DSBs) with hairpinned termini.
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Affiliation(s)
- Katheryn Meek
- Department of Microbiology & Molecular Genetics, and Department of Pathobiology & Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
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16
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Neal JA, Dunger K, Geith K, Meek K. Deciphering the role of distinct DNA-PK phosphorylations at collapsed replication forks. DNA Repair (Amst) 2020; 94:102925. [PMID: 32674014 PMCID: PMC7494621 DOI: 10.1016/j.dnarep.2020.102925] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 06/29/2020] [Accepted: 07/06/2020] [Indexed: 11/29/2022]
Abstract
It has recently been established that the marked sensitivity of ATM deficient cells to topoisomerase poisons like camptothecin (Cpt) results from unrestrained end-joining of DNA ends at collapsed replication forks that is mediated by the non-homologous end joining [NHEJ] pathway and results in the induction of copious numbers of genomic alterations, termed "toxic NHEJ". Ablation of core components of the NHEJ pathway reverses the Cpt sensitivity of ATM deficient cells, but inhibition of DNA-PKcs does not. Here, we show that complete ablation of DNA-PKcs partially reverses the Cpt sensitivity of ATM deficient cells; thus, ATM deficient cells lacking DNA-PKcs are more resistant to Cpt than cells expressing DNA-PKcs. However, the relative sensitivity of DNA-PKcs proficient ATM deficient cells is inversely proportional to DNA-PKcs expression levels. These data suggest that DNA-PK may phosphorylate an ATM target (that contributes to Cpt resistance), explaining partial rescue of Cpt sensitivity in cells expressing high levels of DNA-PKcs. Although crippling NHEJ function by mutagenic blockade of the critical ABCDE autophosphorylation sites in DNA-PKcs also sensitizes cells to Cpt, this sensitization apparently occurs by a distinct mechanism from ATM ablation because blockade of these sites actually rescues ATM deficient cells from toxic NHEJ. These data are consistent with autophosphorylation of the ABCDE sites (and not ATM mediated phosphorylation) in response to Cpt-induced damage. In contrast, blockade of S3205 (an ATM dependent phosphorylation site in DNA-PKcs) that minimally impacts NHEJ, increases Cpt sensitivity. In sum, these data suggest that ATM and DNA-PK cooperate to facilitate Cpt-induced DNA damage, and that ATM phosphorylation of S3205 facilitates appropriate repair at collapsed replication forks.
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Affiliation(s)
- Jessica A Neal
- College of Veterinary Medicine, Department of Microbiology & Molecular Genetics, Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Krista Dunger
- College of Veterinary Medicine, Department of Microbiology & Molecular Genetics, Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Kelly Geith
- College of Veterinary Medicine, Department of Microbiology & Molecular Genetics, Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Katheryn Meek
- College of Veterinary Medicine, Department of Microbiology & Molecular Genetics, Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA.
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17
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Ubiquitylation-Mediated Fine-Tuning of DNA Double-Strand Break Repair. Cancers (Basel) 2020; 12:cancers12061617. [PMID: 32570875 PMCID: PMC7352447 DOI: 10.3390/cancers12061617] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 06/15/2020] [Accepted: 06/17/2020] [Indexed: 01/04/2023] Open
Abstract
The proper function of DNA repair is indispensable for eukaryotic cells since accumulation of DNA damages leads to genome instability and is a major cause of oncogenesis. Ubiquitylation and deubiquitylation play a pivotal role in the precise regulation of DNA repair pathways by coordinating the recruitment and removal of repair proteins at the damaged site. Here, we summarize the most important post-translational modifications (PTMs) involved in DNA double-strand break repair. Although we highlight the most relevant PTMs, we focus principally on ubiquitylation-related processes since these are the most robust regulatory pathways among those of DNA repair.
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18
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Anne Esguerra Z, Watanabe G, Okitsu CY, Hsieh CL, Lieber MR. DNA-PKcs chemical inhibition versus genetic mutation: Impact on the junctional repair steps of V(D)J recombination. Mol Immunol 2020; 120:93-100. [PMID: 32113132 DOI: 10.1016/j.molimm.2020.01.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 01/14/2020] [Accepted: 01/24/2020] [Indexed: 12/20/2022]
Abstract
Spontaneous DNA-PKcs deficiencies in animals result in a severe combined immunodeficiency (SCID) phenotype because DNA-PKcs is required to activate Artemis for V(D)J recombination coding end hairpin opening. The impact on signal joint formation in these spontaneous mutant mammals is variable. Genetically engineered DNA-PKcs null mice and cells from them show a >1,000-fold reduction in coding joint formation and minimal reduction in signal joint formation during V(D)J recombination. Does chemical inhibition of DNA-PKcs mimic this phenotype? M3814 (also known as Nedisertib) is a potent DNA-PKcs inhibitor. We find here that M3814 causes a quantitative reduction in coding joint formation relative to signal joint formation. The sequences of signal and coding junctions were within normal limits, though rare coding joints showed novel features. The signal junctions generally did not show evidence of resection into the signal ends that is often seen in cells that have genetic defects in DNA-PKcs. Comparison of the chemical inhibition findings here with the known results for spontaneous and engineered DNA-PKcs mutant mammals is informative for considering pharmacologic small molecule inhibition of DNA-PKcs in various types of neoplasia.
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Affiliation(s)
- Z Anne Esguerra
- USC Norris Comprehensive Cancer Ctr, Departments of Pathology, of Biochemistry & Molecular Biology, of Molecular Microbiology & Immunology, University of Southern California Keck School of Medicine, and the Molecular and Computational Biology Section of the Department of Biological Sciences, 1441 Eastlake Ave., Rm. 5428, Los Angeles, CA, 90089-9176, United States
| | - Go Watanabe
- USC Norris Comprehensive Cancer Ctr, Departments of Pathology, of Biochemistry & Molecular Biology, of Molecular Microbiology & Immunology, University of Southern California Keck School of Medicine, and the Molecular and Computational Biology Section of the Department of Biological Sciences, 1441 Eastlake Ave., Rm. 5428, Los Angeles, CA, 90089-9176, United States
| | - Cindy Y Okitsu
- Department of Urology, USC Norris Comprehensive Cancer Ctr, Los Angeles, CA, 90089 United States
| | - Chih-Lin Hsieh
- Department of Urology, USC Norris Comprehensive Cancer Ctr, Los Angeles, CA, 90089 United States
| | - Michael R Lieber
- USC Norris Comprehensive Cancer Ctr, Departments of Pathology, of Biochemistry & Molecular Biology, of Molecular Microbiology & Immunology, University of Southern California Keck School of Medicine, and the Molecular and Computational Biology Section of the Department of Biological Sciences, 1441 Eastlake Ave., Rm. 5428, Los Angeles, CA, 90089-9176, United States.
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19
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Serrano-Benítez A, Cortés-Ledesma F, Ruiz JF. "An End to a Means": How DNA-End Structure Shapes the Double-Strand Break Repair Process. Front Mol Biosci 2020; 6:153. [PMID: 31998749 PMCID: PMC6965357 DOI: 10.3389/fmolb.2019.00153] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 12/11/2019] [Indexed: 12/12/2022] Open
Abstract
Endogenously-arising DNA double-strand breaks (DSBs) rarely harbor canonical 5′-phosphate, 3′-hydroxyl moieties at the ends, which are, regardless of the pathway used, ultimately required for their repair. Cells are therefore endowed with a wide variety of enzymes that can deal with these chemical and structural variations and guarantee the formation of ligatable termini. An important distinction is whether the ends are directly “unblocked” by specific enzymatic activities without affecting the integrity of the DNA molecule and its sequence, or whether they are “processed” by unspecific nucleases that remove nucleotides from the termini. DNA end structure and configuration, therefore, shape the repair process, its requirements, and, importantly, its final outcome. Thus, the molecular mechanisms that coordinate and integrate the cellular response to blocked DSBs, although still largely unexplored, can be particularly relevant for maintaining genome integrity and avoiding malignant transformation and cancer.
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Affiliation(s)
- Almudena Serrano-Benítez
- Andalusian Center of Molecular Biology and Regenerative Medicine (CABIMER-CSIC-University of Seville-Pablo de Olavide University), Seville, Spain
| | - Felipe Cortés-Ledesma
- Andalusian Center of Molecular Biology and Regenerative Medicine (CABIMER-CSIC-University of Seville-Pablo de Olavide University), Seville, Spain.,Topology and DNA breaks Group, Spanish National Cancer Research Center, Madrid, Spain
| | - Jose F Ruiz
- Andalusian Center of Molecular Biology and Regenerative Medicine (CABIMER-CSIC-University of Seville-Pablo de Olavide University), Seville, Spain.,Department of Plant Biochemistry and Molecular Biology, University of Seville, Seville, Spain
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20
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Buzon B, Grainger R, Huang S, Rzadki C, Junop MS. Structure-specific endonuclease activity of SNM1A enables processing of a DNA interstrand crosslink. Nucleic Acids Res 2019; 46:9057-9066. [PMID: 30165656 PMCID: PMC6158701 DOI: 10.1093/nar/gky759] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 08/20/2018] [Indexed: 01/09/2023] Open
Abstract
DNA interstrand crosslinks (ICLs) covalently join opposing strands, blocking both replication and transcription, therefore making ICL-inducing compounds highly toxic and ideal anti-cancer agents. While incisions surrounding the ICL are required to remove damaged DNA, it is currently unclear which endonucleases are needed for this key event. SNM1A has been shown to play an important function in human ICL repair, however its suggested role has been limited to exonuclease activity and not strand incision. Here we show that SNM1A has endonuclease activity, having the ability to cleave DNA structures that arise during the initiation of ICL repair. In particular, this endonuclease activity cleaves single-stranded DNA. Given that unpaired DNA regions occur 5′ to an ICL, these findings suggest SNM1A may act as either an endonuclease and/or exonuclease during ICL repair. This finding is significant as it expands the potential role of SNM1A in ICL repair.
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Affiliation(s)
- Beverlee Buzon
- Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster, University, Hamilton, Ontario L8N 3Z5, Canada.,Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, Ontario N6A 5C1, Canada
| | - Ryan Grainger
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, Ontario N6A 5C1, Canada
| | - Simon Huang
- Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster, University, Hamilton, Ontario L8N 3Z5, Canada
| | - Cameron Rzadki
- Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster, University, Hamilton, Ontario L8N 3Z5, Canada
| | - Murray S Junop
- Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster, University, Hamilton, Ontario L8N 3Z5, Canada.,Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, Ontario N6A 5C1, Canada
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21
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Pannunzio NR, Watanabe G, Lieber MR. Nonhomologous DNA end-joining for repair of DNA double-strand breaks. J Biol Chem 2017; 293:10512-10523. [PMID: 29247009 DOI: 10.1074/jbc.tm117.000374] [Citation(s) in RCA: 314] [Impact Index Per Article: 44.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Nonhomologous DNA end-joining (NHEJ) is the predominant double-strand break (DSB) repair pathway throughout the cell cycle and accounts for nearly all DSB repair outside of the S and G2 phases. NHEJ relies on Ku to thread onto DNA termini and thereby improve the affinity of the NHEJ enzymatic components consisting of polymerases (Pol μ and Pol λ), a nuclease (the Artemis·DNA-PKcs complex), and a ligase (XLF·XRCC4·Lig4 complex). Each of the enzymatic components is distinctive for its versatility in acting on diverse incompatible DNA end configurations coupled with a flexibility in loading order, resulting in many possible junctional outcomes from one DSB. DNA ends can either be directly ligated or, if the ends are incompatible, processed until a ligatable configuration is achieved that is often stabilized by up to 4 bp of terminal microhomology. Processing of DNA ends results in nucleotide loss or addition, explaining why DSBs repaired by NHEJ are rarely restored to their original DNA sequence. Thus, NHEJ is a single pathway with multiple enzymes at its disposal to repair DSBs, resulting in a diversity of repair outcomes.
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Affiliation(s)
- Nicholas R Pannunzio
- From the Departments of Pathology, Biochemistry and Molecular Biology, and Molecular Microbiology and Immunology, Section of Molecular and Computational Biology, Department of Biological Sciences, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California 90033
| | - Go Watanabe
- From the Departments of Pathology, Biochemistry and Molecular Biology, and Molecular Microbiology and Immunology, Section of Molecular and Computational Biology, Department of Biological Sciences, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California 90033
| | - Michael R Lieber
- From the Departments of Pathology, Biochemistry and Molecular Biology, and Molecular Microbiology and Immunology, Section of Molecular and Computational Biology, Department of Biological Sciences, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California 90033
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22
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Sidorova J. A game of substrates: replication fork remodeling and its roles in genome stability and chemo-resistance. Cell Stress 2017; 1:115-133. [PMID: 29355244 PMCID: PMC5771654 DOI: 10.15698/cst2017.12.114] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
During the hours that human cells spend in the DNA synthesis (S) phase of the cell cycle, they may encounter adversities such as DNA damage or shortage of nucleotides. Under these stresses, replication forks in DNA may experience slowing, stalling, and breakage. Fork remodeling mechanisms, which stabilize slow or stalled replication forks and ensure their ability to continue or resume replication, protect cells from genomic instability and carcinogenesis. Fork remodeling includes DNA strand exchanges that result in annealing of newly synthesized strands (fork reversal), controlled DNA resection, and cleavage of DNA strands. Defects in major tumor suppressor genes BRCA1 and BRCA2, and a subset of the Fanconi Anemia genes have been shown to result in deregulation in fork remodeling, and most prominently, loss of kilobases of nascent DNA from stalled replication forks. This phenomenon has recently gained spotlight as a potential marker and mediator of chemo-sensitivity in cancer cells and, conversely, its suppression - as a hallmark of acquired chemo-resistance. Moreover, nascent strand degradation at forks is now known to also trigger innate immune response to self-DNA. An increasingly sophisticated molecular description of these events now points at a combination of unbalanced fork reversal and end-resection as a root cause, yet also reveals the multi-layered complexity and heterogeneity of the underlying processes in normal and cancer cells.
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Affiliation(s)
- Julia Sidorova
- Department of Pathology, University of Washington, Seattle, Washington, USA
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23
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Gerodimos CA, Chang HHY, Watanabe G, Lieber MR. Effects of DNA end configuration on XRCC4-DNA ligase IV and its stimulation of Artemis activity. J Biol Chem 2017; 292:13914-13924. [PMID: 28696258 DOI: 10.1074/jbc.m117.798850] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 07/05/2017] [Indexed: 11/06/2022] Open
Abstract
In humans, nonhomologous DNA end-joining (NHEJ) is the major pathway by which DNA double-strand breaks are repaired. Recognition of each broken DNA end by the DNA repair protein Ku is the first step in NHEJ, followed by the iterative binding of nucleases, DNA polymerases, and the XRCC4-DNA ligase IV (X4-LIV) complex in an order influenced by the configuration of the two DNA ends at the break site. The endonuclease Artemis improves joining efficiency by functioning in a complex with DNA-dependent protein kinase, catalytic subunit (DNA-PKcs) that carries out endonucleolytic cleavage of 5' and 3' overhangs. Previously, we observed that X4-LIV alone can stimulate Artemis activity on 3' overhangs, but this DNA-PKcs-independent endonuclease activity of Artemis awaited confirmation. Here, using in vitro nuclease and ligation assays, we find that stimulation of Artemis nuclease activity by X4-LIV and the efficiency of blunt-end ligation are determined by structural configurations at the DNA end. Specifically, X4-LIV stimulated Artemis to cut near the end of 3' overhangs without the involvement of other NHEJ proteins. Of note, this ligase complex is not able to stimulate Artemis activity at hairpins or at 5' overhangs. We also found that X4-LIV and DNA-PKcs interfere with one another with respect to stimulating Artemis activity at 3' overhangs, favoring the view that these NHEJ proteins are sequentially rather than concurrently recruited to DNA ends. These data suggest specific functional and positional relationships among these components that explain genetic and molecular features of NHEJ and V(D)J recombination within cells.
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Affiliation(s)
- Christina A Gerodimos
- From the Departments of Pathology, Biochemistry & Molecular Biology, and Molecular Microbiology & Immunology and the Department of Biological Sciences, Section of Molecular & Computational Biology, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California 90033
| | - Howard H Y Chang
- From the Departments of Pathology, Biochemistry & Molecular Biology, and Molecular Microbiology & Immunology and the Department of Biological Sciences, Section of Molecular & Computational Biology, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California 90033
| | - Go Watanabe
- From the Departments of Pathology, Biochemistry & Molecular Biology, and Molecular Microbiology & Immunology and the Department of Biological Sciences, Section of Molecular & Computational Biology, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California 90033
| | - Michael R Lieber
- From the Departments of Pathology, Biochemistry & Molecular Biology, and Molecular Microbiology & Immunology and the Department of Biological Sciences, Section of Molecular & Computational Biology, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California 90033.
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Non-homologous DNA end joining and alternative pathways to double-strand break repair. Nat Rev Mol Cell Biol 2017; 18:495-506. [PMID: 28512351 DOI: 10.1038/nrm.2017.48] [Citation(s) in RCA: 975] [Impact Index Per Article: 139.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
DNA double-strand breaks (DSBs) are the most dangerous type of DNA damage because they can result in the loss of large chromosomal regions. In all mammalian cells, DSBs that occur throughout the cell cycle are repaired predominantly by the non-homologous DNA end joining (NHEJ) pathway. Defects in NHEJ result in sensitivity to ionizing radiation and the ablation of lymphocytes. The NHEJ pathway utilizes proteins that recognize, resect, polymerize and ligate the DNA ends in a flexible manner. This flexibility permits NHEJ to function on a wide range of DNA-end configurations, with the resulting repaired DNA junctions often containing mutations. In this Review, we discuss the most recent findings regarding the relative involvement of the different NHEJ proteins in the repair of various DNA-end configurations. We also discuss the shunting of DNA-end repair to the auxiliary pathways of alternative end joining (a-EJ) or single-strand annealing (SSA) and the relevance of these different pathways to human disease.
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25
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Nikjoo H, Taleei R, Liamsuwan T, Liljequist D, Emfietzoglou D. Perspectives in radiation biophysics: From radiation track structure simulation to mechanistic models of DNA damage and repair. Radiat Phys Chem Oxf Engl 1993 2016. [DOI: 10.1016/j.radphyschem.2016.05.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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26
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Liang S, Esswein SR, Ochi T, Wu Q, Ascher DB, Chirgadze D, Sibanda BL, Blundell TL. Achieving selectivity in space and time with DNA double-strand-break response and repair: molecular stages and scaffolds come with strings attached. Struct Chem 2016. [DOI: 10.1007/s11224-016-0841-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Chang HHY, Lieber MR. Structure-Specific nuclease activities of Artemis and the Artemis: DNA-PKcs complex. Nucleic Acids Res 2016; 44:4991-7. [PMID: 27198222 PMCID: PMC4914130 DOI: 10.1093/nar/gkw456] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 05/06/2016] [Indexed: 12/23/2022] Open
Abstract
Artemis is a vertebrate nuclease with both endo- and exonuclease activities that acts on a wide range of nucleic acid substrates. It is the main nuclease in the non-homologous DNA end-joining pathway (NHEJ). Not only is Artemis important for the repair of DNA double-strand breaks (DSBs) in NHEJ, it is essential in opening the DNA hairpin intermediates that are formed during V(D)J recombination. Thus, humans with Artemis deficiencies do not have T- or B-lymphocytes and are diagnosed with severe combined immunodeficiency (SCID). While Artemis is the only vertebrate nuclease capable of opening DNA hairpins, it has also been found to act on other DNA substrates that share common structural features. Here, we discuss the key structural features that all Artemis DNA substrates have in common, thus providing a basis for understanding how this structure-specific nuclease recognizes its DNA targets.
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Affiliation(s)
- Howard H Y Chang
- University of Southern California Keck School of Medicine, Norris Comprehensive Cancer Center, Los Angeles, CA 90089, USA
| | - Michael R Lieber
- University of Southern California Keck School of Medicine, Norris Comprehensive Cancer Center, Los Angeles, CA 90089, USA
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Averbeck NB, Topsch J, Scholz M, Kraft-Weyrather W, Durante M, Taucher-Scholz G. Efficient Rejoining of DNA Double-Strand Breaks despite Increased Cell-Killing Effectiveness following Spread-Out Bragg Peak Carbon-Ion Irradiation. Front Oncol 2016; 6:28. [PMID: 26904506 PMCID: PMC4751252 DOI: 10.3389/fonc.2016.00028] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 01/25/2016] [Indexed: 12/12/2022] Open
Abstract
Radiotherapy of solid tumors with charged particles holds several advantages in comparison to photon therapy; among them conformal dose distribution in the tumor, improved sparing of tumor-surrounding healthy tissue, and an increased relative biological effectiveness (RBE) in the tumor target volume in the case of ions heavier than protons. A crucial factor of the biological effects is DNA damage, of which DNA double-strand breaks (DSBs) are the most deleterious. The reparability of these lesions determines the cell survival after irradiation and thus the RBE. Interestingly, using phosphorylated H2AX as a DSB marker, our data in human fibroblasts revealed that after therapy-relevant spread-out Bragg peak irradiation with carbon ions DSBs are very efficiently rejoined, despite an increased RBE for cell survival. This suggests that misrepair plays an important role in the increased RBE of heavy-ion radiation. Possible sources of erroneous repair will be discussed.
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Affiliation(s)
- Nicole B Averbeck
- Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH , Darmstadt , Germany
| | - Jana Topsch
- Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH , Darmstadt , Germany
| | - Michael Scholz
- Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH , Darmstadt , Germany
| | - Wilma Kraft-Weyrather
- Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH , Darmstadt , Germany
| | - Marco Durante
- Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany; Technische Universität Darmstadt, Darmstadt, Germany
| | - Gisela Taucher-Scholz
- Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany; Technische Universität Darmstadt, Darmstadt, Germany
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29
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Borrego-Soto G, Ortiz-López R, Rojas-Martínez A. Ionizing radiation-induced DNA injury and damage detection in patients with breast cancer. Genet Mol Biol 2015; 38:420-32. [PMID: 26692152 PMCID: PMC4763322 DOI: 10.1590/s1415-475738420150019] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 07/15/2015] [Indexed: 12/26/2022] Open
Abstract
Breast cancer is the most common malignancy in women. Radiotherapy is frequently used in patients with breast cancer, but some patients may be more susceptible to ionizing radiation, and increased exposure to radiation sources may be associated to radiation adverse events. This susceptibility may be related to deficiencies in DNA repair mechanisms that are activated after cell-radiation, which causes DNA damage, particularly DNA double strand breaks. Some of these genetic susceptibilities in DNA-repair mechanisms are implicated in the etiology of hereditary breast/ovarian cancer (pathologic mutations in the BRCA 1 and 2 genes), but other less penetrant variants in genes involved in sporadic breast cancer have been described. These same genetic susceptibilities may be involved in negative radiotherapeutic outcomes. For these reasons, it is necessary to implement methods for detecting patients who are susceptible to radiotherapy-related adverse events. This review discusses mechanisms of DNA damage and repair, genes related to these functions, and the diagnosis methods designed and under research for detection of breast cancer patients with increased radiosensitivity.
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Affiliation(s)
- Gissela Borrego-Soto
- Departamento de Bioquímica y Medicina Molecular, Facultad de
Medicina, Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, Mexico
- Centro de Investigación y Desarrollo en Ciencias de la Salud,
Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, Mexico
| | - Rocío Ortiz-López
- Departamento de Bioquímica y Medicina Molecular, Facultad de
Medicina, Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, Mexico
- Centro de Investigación y Desarrollo en Ciencias de la Salud,
Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, Mexico
| | - Augusto Rojas-Martínez
- Departamento de Bioquímica y Medicina Molecular, Facultad de
Medicina, Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, Mexico
- Centro de Investigación y Desarrollo en Ciencias de la Salud,
Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, Mexico
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30
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Chang HHY, Watanabe G, Lieber MR. Unifying the DNA end-processing roles of the artemis nuclease: Ku-dependent artemis resection at blunt DNA ends. J Biol Chem 2015; 290:24036-50. [PMID: 26276388 DOI: 10.1074/jbc.m115.680900] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Indexed: 11/06/2022] Open
Abstract
Artemis is a member of the metallo-β-lactamase protein family of nucleases. It is essential in vertebrates because, during V(D)J recombination, the RAG complex generates hairpins when it creates the double strand breaks at V, D, and J segments, and Artemis is required to open the hairpins so that they can be joined. Artemis is a diverse endo- and exonuclease, and creating a unified model for its wide range of nuclease properties has been challenging. Here we show that Artemis resects iteratively into blunt DNA ends with an efficiency that reflects the AT-richness of the DNA end. GC-rich ends are not cut by Artemis alone because of a requirement for DNA end breathing (and confirmed using fixed pseudo-Y structures). All DNA ends are cut when both the DNA-dependent protein kinase catalytic subunit and Ku accompany Artemis but not when Ku is omitted. These are the first biochemical data demonstrating a Ku dependence of Artemis action on DNA ends of any configuration. The action of Artemis at blunt DNA ends is slower than at overhangs, consistent with a requirement for a slow DNA end breathing step preceding the cut. The AT sequence dependence, the order of strand cutting, the length of the cuts, and the Ku-dependence of Artemis action at blunt ends can be reconciled with the other nucleolytic properties of both Artemis and Artemis·DNA-PKcs in a model incorporating DNA end breathing of blunt ends to form transient single to double strand boundaries that have structural similarities to hairpins and fixed 5' and 3' overhangs.
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Affiliation(s)
- Howard H Y Chang
- From the Departments of Pathology, Biochemistry and Molecular Biology, Biological Sciences, and Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Norris Comprehensive Cancer Center, Los Angeles, California
| | - Go Watanabe
- From the Departments of Pathology, Biochemistry and Molecular Biology, Biological Sciences, and Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Norris Comprehensive Cancer Center, Los Angeles, California
| | - Michael R Lieber
- From the Departments of Pathology, Biochemistry and Molecular Biology, Biological Sciences, and Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Norris Comprehensive Cancer Center, Los Angeles, California
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31
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Pei XY, Bralley P, Jones GH, Luisi BF. Linkage of catalysis and 5' end recognition in ribonuclease RNase J. Nucleic Acids Res 2015; 43:8066-76. [PMID: 26253740 PMCID: PMC4652760 DOI: 10.1093/nar/gkv732] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 07/07/2015] [Indexed: 11/25/2022] Open
Abstract
In diverse bacterial species, the turnover and processing of many RNAs is mediated by the ribonuclease RNase J, a member of the widely occurring metallo-β-lactamase enzyme family. We present crystal structures of Streptomyces coelicolor RNase J with bound RNA in pre- and post-cleavage states, at 2.27 Å and 2.80 Å resolution, respectively. These structures reveal snapshots of the enzyme cleaving substrate directionally and sequentially from the 5′ terminus. In the pre-cleavage state, a water molecule is coordinated to a zinc ion pair in the active site but is imperfectly oriented to launch a nucleophilic attack on the phosphate backbone. A conformational switch is envisaged that enables the in-line positioning of the attacking water and may be facilitated by magnesium ions. Adjacent to the scissile bond, four bases are stacked in a tightly sandwiching pocket, and mutagenesis results indicate that this organization helps to drive processive exo-ribonucleolytic cleavage. Like its numerous homologues, S. coelicolor RNase J can also cleave some RNA internally, and the structural data suggest how the preference for exo- versus endo-cleavage mode is linked with recognition of the chemical status of the substrate's 5′ end.
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Affiliation(s)
- Xue-Yuan Pei
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
| | | | - George H Jones
- Department of Biology, Emory University, Atlanta Georgia, USA
| | - Ben F Luisi
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
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32
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Role for Artemis nuclease in the repair of radiation-induced DNA double strand breaks by alternative end joining. DNA Repair (Amst) 2015; 31:29-40. [DOI: 10.1016/j.dnarep.2015.04.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 04/14/2015] [Accepted: 04/15/2015] [Indexed: 11/24/2022]
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The fidelity of the ligation step determines how ends are resolved during nonhomologous end joining. Nat Commun 2014; 5:4286. [PMID: 24989324 PMCID: PMC4107315 DOI: 10.1038/ncomms5286] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 06/03/2014] [Indexed: 12/21/2022] Open
Abstract
Nonhomologous end joining (NHEJ) can effectively resolve chromosome breaks despite diverse end structures, but it is unclear how the steps employed for resolution are determined. We sought to address this question by analyzing cellular NHEJ of ends with systematically mispaired and damaged termini. We show NHEJ is uniquely proficient at bypassing subtle terminal mispairs and radiomimetic damage by direct ligation. Nevertheless, bypass ability varies widely, with increases in mispair severity gradually reducing bypass products from 85% to 6%. End-processing by nucleases and polymerases is increased to compensate, though paths with the fewest number of steps to generate a substrate suitable for ligation are favored. Thus, both the frequency and nature of end processing are tailored to meet the needs of the ligation step. We propose a model where the ligase organizes all steps during NHEJ within the stable paired-end complex to limit end processing and associated errors.
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34
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Ochi T, Wu Q, Blundell TL. The spatial organization of non-homologous end joining: from bridging to end joining. DNA Repair (Amst) 2014; 17:98-109. [PMID: 24636752 PMCID: PMC4037875 DOI: 10.1016/j.dnarep.2014.02.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 01/27/2014] [Accepted: 02/10/2014] [Indexed: 01/24/2023]
Abstract
Non-homologous end joining (NHEJ) repairs DNA double-strand breaks generated by DNA damage and also those occurring in V(D)J recombination in immunoglobulin and T cell receptor production in the immune system. In NHEJ DNA-PKcs assembles with Ku heterodimer on the DNA ends at double-strand breaks, in order to bring the broken ends together and to assemble other proteins, including DNA ligase IV (LigIV), required for DNA repair. Here we focus on structural aspects of the interactions of LigIV with XRCC4, XLF, Artemis and DNA involved in the bridging and end-joining steps of NHEJ. We begin with a discussion of the role of XLF, which interacts with Ku and forms a hetero-filament with XRCC4; this likely forms a scaffold bridging the DNA ends. We then review the well-defined interaction of XRCC4 with LigIV, and discuss the possibility of this complex interrupting the filament formation, so positioning the ligase at the correct positions close to the broken ends. We also describe the interactions of LigIV with Artemis, the nuclease that prepares the ends for ligation and also interacts with DNA-PK. Lastly we review the likely affects of Mendelian mutations on these multiprotein assemblies and their impacts on the form of inherited disease.
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Affiliation(s)
- Takashi Ochi
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK.
| | - Qian Wu
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Tom L Blundell
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
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35
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Li S, Chang HH, Niewolik D, Hedrick MP, Pinkerton AB, Hassig CA, Schwarz K, Lieber MR. Evidence that the DNA endonuclease ARTEMIS also has intrinsic 5'-exonuclease activity. J Biol Chem 2014; 289:7825-34. [PMID: 24500713 DOI: 10.1074/jbc.m113.544874] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
ARTEMIS is a member of the metallo-β-lactamase protein family. ARTEMIS has endonuclease activity at DNA hairpins and at 5'- and 3'-DNA overhangs of duplex DNA, and this endonucleolytic activity is dependent upon DNA-PKcs. There has been uncertainty about whether ARTEMIS also has 5'-exonuclease activity on single-stranded DNA and 5'-overhangs, because this 5'-exonuclease is not dependent upon DNA-PKcs. Here, we show that the 5'-exonuclease and the endonuclease activities co-purify. Second, we show that a point mutant of ARTEMIS at a putative active site residue (H115A) markedly reduces both the endonuclease activity and the 5'-exonuclease activity. Third, divalent cation effects on the 5'-exonuclease and the endonuclease parallel one another. Fourth, both the endonuclease activity and 5'-exonuclease activity of ARTEMIS can be blocked in parallel by small molecule inhibitors, which do not block unrelated nucleases. We conclude that the 5'-exonuclease is intrinsic to ARTEMIS, making it relevant to the role of ARTEMIS in nonhomologous DNA end joining.
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Affiliation(s)
- Sicong Li
- From the Departments of Pathology, Biochemistry and Molecular Biology, Biological Sciences, and Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Norris Comprehensive Cancer Center, Los Angeles, California 90089-9176
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36
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Ribonucleolytic resection is required for repair of strand displaced nonhomologous end-joining intermediates. Proc Natl Acad Sci U S A 2013; 110:E1984-91. [PMID: 23671117 DOI: 10.1073/pnas.1302616110] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Nonhomologous end-joining (NHEJ) pathways repair DNA double-strand breaks (DSBs) in eukaryotes and many prokaryotes, although it is not reported to operate in the third domain of life, archaea. Here, we describe a complete NHEJ complex, consisting of DNA ligase (Lig), polymerase (Pol), phosphoesterase (PE), and Ku from a mesophillic archaeon, Methanocella paludicola (Mpa). Mpa Lig has limited DNA nick-sealing activity but is efficient in ligating nicks containing a 3' ribonucleotide. Mpa Pol preferentially incorporates nucleoside triphosphates onto a DNA primer strand, filling DNA gaps in annealed breaks. Mpa PE sequentially removes 3' phosphates and ribonucleotides from primer strands, leaving a ligatable terminal 3' monoribonucleotide. These proteins, together with the DNA end-binding protein Ku, form a functional NHEJ break-repair apparatus that is highly homologous to the bacterial complex. Although the major roles of Pol and Lig in break repair have been reported, PE's function in NHEJ has remained obscure. We establish that PE is required for ribonucleolytic resection of RNA intermediates at annealed DSBs. Polymerase-catalyzed strand-displacement synthesis on DNA gaps can result in the formation of nonligatable NHEJ intermediates. The function of PE in NHEJ repair is to detect and remove inappropriately incorporated ribonucleotides or phosphates from 3' ends of annealed DSBs to configure the termini for ligation. Thus, PE prevents the accumulation of abortive genotoxic DNA intermediates arising from strand displacement synthesis that otherwise would be refractory to repair.
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37
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Malu S, Malshetty V, Francis D, Cortes P. Role of non-homologous end joining in V(D)J recombination. Immunol Res 2013; 54:233-46. [PMID: 22569912 DOI: 10.1007/s12026-012-8329-z] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The pathway of V(D)J recombination was discovered almost three decades ago. Yet it continues to baffle scientists because of its inherent complexity and the multiple layers of regulation that are required to efficiently generate a diverse repertoire of T and B cells. The non-homologous end-joining (NHEJ) DNA repair pathway is an integral part of the V(D)J reaction, and its numerous players perform critical functions in generating this vast diversity, while ensuring genomic stability. In this review, we summarize the efforts of a number of laboratories including ours in providing the mechanisms of V(D)J regulation with a focus on the NHEJ pathway. This involves discovering new players, unraveling unknown roles for known components, and understanding how deregulation of these pathways contributes to generation of primary immunodeficiencies. A long-standing interest of our laboratory has been to elucidate various mechanisms that control RAG activity. Our recent work has focused on understanding the multiple protein-protein interactions and protein-DNA interactions during V(D)J recombination, which allow efficient and regulated generation of the antigen receptors. Exploring how deregulation of this process contributes to immunodeficiencies also continues to be an important area of research for our group.
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Affiliation(s)
- Shruti Malu
- Department of Medicine, Immunology Institute, Mount Sinai School of Medicine, 1425 Madison Avenue, New York, NY 10029, USA
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38
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Li S, Kanno SI, Watanabe R, Ogiwara H, Kohno T, Watanabe G, Yasui A, Lieber MR. Polynucleotide kinase and aprataxin-like forkhead-associated protein (PALF) acts as both a single-stranded DNA endonuclease and a single-stranded DNA 3' exonuclease and can participate in DNA end joining in a biochemical system. J Biol Chem 2011; 286:36368-77. [PMID: 21885877 DOI: 10.1074/jbc.m111.287797] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Polynucleotide kinase and aprataxin-like forkhead-associated protein (PALF, also called aprataxin- and PNK-like factor (APLF)) has been shown to have nuclease activity and to use its forkhead-associated domain to bind to x-ray repair complementing defective repair in Chinese hamster cells 4 (XRCC4). Because XRCC4 is a key component of the ligase IV complex that is central to the nonhomologous DNA end joining (NHEJ) pathway, this raises the possibility that PALF might play a role in NHEJ. For this reason, we further studied the nucleolytic properties of PALF, and we searched for any modulation of PALF by NHEJ components. We verified that PALF has 3' exonuclease activity. However, PALF also possesses single-stranded DNA endonuclease activity. This single-stranded DNA endonuclease activity can act at all single-stranded sites except those within four nucleotides 3' of a double-stranded DNA junction, suggesting that PALF minimally requires approximately four nucleotides of single-strandedness. Ku, DNA-dependent protein kinase catalytic subunit, and XRCC4-DNA ligase IV do not modulate PALF nuclease activity on single-stranded DNA or overhangs of duplex substrates. PALF does not open DNA hairpins. However, in a reconstituted end joining assay that includes Ku, XRCC4-DNA ligase IV, and PALF, PALF is able to resect 3' overhanging nucleotides and permit XRCC4-DNA ligase IV to complete the joining process in a manner that is as efficient as Artemis. Reduction of PALF in vivo reduces the joining of incompatible DNA ends. Hence, PALF can function in concert with other NHEJ proteins.
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Affiliation(s)
- Sicong Li
- Department of Pathology, Norris Comprehensive Cancer Center, Los Angeles, California 90089-9176, USA
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39
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Wang AT, Sengerová B, Cattell E, Inagawa T, Hartley JM, Kiakos K, Burgess-Brown NA, Swift LP, Enzlin JH, Schofield CJ, Gileadi O, Hartley JA, McHugh PJ. Human SNM1A and XPF-ERCC1 collaborate to initiate DNA interstrand cross-link repair. Genes Dev 2011; 25:1859-70. [PMID: 21896658 PMCID: PMC3175721 DOI: 10.1101/gad.15699211] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 07/20/2011] [Indexed: 12/24/2022]
Abstract
One of the major DNA interstrand cross-link (ICL) repair pathways in mammalian cells is coupled to replication, but the mechanistic roles of the critical factors involved remain largely elusive. Here, we show that purified human SNM1A (hSNM1A), which exhibits a 5'-3' exonuclease activity, can load from a single DNA nick and digest past an ICL on its substrate strand. hSNM1A-depleted cells are ICL-sensitive and accumulate replication-associated DNA double-strand breaks (DSBs), akin to ERCC1-depleted cells. These DSBs are Mus81-induced, indicating that replication fork cleavage by Mus81 results from the failure of the hSNM1A- and XPF-ERCC1-dependent ICL repair pathway. Our results reveal how collaboration between hSNM1A and XPF-ERCC1 is necessary to initiate ICL repair in replicating human cells.
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Affiliation(s)
- Anderson T. Wang
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
| | - Blanka Sengerová
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
| | - Emma Cattell
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
| | - Takabumi Inagawa
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
| | - Janet M. Hartley
- Cancer Research UK Drug–DNA Interactions Research Group, UCL Cancer Institute, University College London, London WC1E 6BT, United Kingdom
| | - Konstantinos Kiakos
- Cancer Research UK Drug–DNA Interactions Research Group, UCL Cancer Institute, University College London, London WC1E 6BT, United Kingdom
| | | | - Lonnie P. Swift
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
| | - Jacqueline H. Enzlin
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
| | | | - Opher Gileadi
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom
| | - John A. Hartley
- Cancer Research UK Drug–DNA Interactions Research Group, UCL Cancer Institute, University College London, London WC1E 6BT, United Kingdom
| | - Peter J. McHugh
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
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40
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Allen C, Ashley AK, Hromas R, Nickoloff JA. More forks on the road to replication stress recovery. J Mol Cell Biol 2011; 3:4-12. [PMID: 21278446 DOI: 10.1093/jmcb/mjq049] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
High-fidelity replication of DNA, and its accurate segregation to daughter cells, is critical for maintaining genome stability and suppressing cancer. DNA replication forks are stalled by many DNA lesions, activating checkpoint proteins that stabilize stalled forks. Stalled forks may eventually collapse, producing a broken DNA end. Fork restart is typically mediated by proteins initially identified by their roles in homologous recombination repair of DNA double-strand breaks (DSBs). In recent years, several proteins involved in DSB repair by non-homologous end joining (NHEJ) have been implicated in the replication stress response, including DNA-PKcs, Ku, DNA Ligase IV-XRCC4, Artemis, XLF and Metnase. It is currently unclear whether NHEJ proteins are involved in the replication stress response through indirect (signaling) roles, and/or direct roles involving DNA end joining. Additional complexity in the replication stress response centers around RPA, which undergoes significant post-translational modification after stress, and RAD52, a conserved HR protein whose role in DSB repair may have shifted to another protein in higher eukaryotes, such as BRCA2, but retained its role in fork restart. Most cancer therapeutic strategies create DNA replication stress. Thus, it is imperative to gain a better understanding of replication stress response proteins and pathways to improve cancer therapy.
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Affiliation(s)
- Chris Allen
- Department of Environmental and Radiological Health Sciences, Colorado State University, Ft Collins, CO 80523, USA
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Pawelczak KS, Bennett SM, Turchi JJ. Coordination of DNA-PK activation and nuclease processing of DNA termini in NHEJ. Antioxid Redox Signal 2011; 14:2531-43. [PMID: 20698792 PMCID: PMC3096510 DOI: 10.1089/ars.2010.3368] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
DNA double-strand breaks (DSB), particularly those induced by ionizing radiation (IR), are complex lesions that can be cytotoxic if not properly repaired. IR-induced DSB often have DNA termini modifications, including thymine glycols, ring fragmentation, 3'-phosphoglycolates, 5'-hydroxyl groups, and abasic sites. Nonhomologous end joining (NHEJ) is a major pathway responsible for the repair of these complex breaks. Proteins involved in NHEJ include the Ku 70/80 heterodimer, DNA-PKcs, processing proteins including Artemis and DNA polymerases μ and λ, XRCC4, DNA ligase IV, and XLF. We will discuss the role of the physical and functional interactions of DNA-PK as a result of activation, with an emphasis on DNA structure, chemistry, and sequence. With the diversity of IR induced DSB, it is becoming increasingly clear that multiple DNA processing enzymes are likely necessary for effective repair of a break. We will explore the roles of several important processing enzymes, with a focus on the nuclease Artemis and its role in processing diverse DSB. The effect of DNA termini on both DNA-PK and Artemis activity will be analyzed from a structural and biochemical view.
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Affiliation(s)
- Katherine S Pawelczak
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 980 W. Walnut St., Indianapolis, IN 46202, USA
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Mohapatra S, Kawahara M, Khan IS, Yannone SM, Povirk LF. Restoration of G1 chemo/radioresistance and double-strand-break repair proficiency by wild-type but not endonuclease-deficient Artemis. Nucleic Acids Res 2011; 39:6500-10. [PMID: 21531702 PMCID: PMC3159448 DOI: 10.1093/nar/gkr257] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Deficiency in Artemis is associated with lack of V(D)J recombination, sensitivity to radiation and radiomimetic drugs, and failure to repair a subset of DNA double-strand breaks (DSBs). Artemis harbors an endonuclease activity that trims both 5′- and 3′-ends of DSBs. To examine whether endonucleolytic trimming of terminally blocked DSBs by Artemis is a biologically relevant function, Artemis-deficient fibroblasts were stably complemented with either wild-type Artemis or an endonuclease-deficient D165N mutant. Wild-type Artemis completely restored resistance to γ-rays, bleomycin and neocarzinostatin, and also restored DSB-repair proficiency in G0/G1 phase as measured by pulsed-field gel electrophoresis and repair focus resolution. In contrast, cells expressing the D165N mutant, even at very high levels, remained as chemo/radiosensitive and repair deficient as the parental cells, as evidenced by persistent γ-H2AX, 53BP1 and Mre11 foci that slowly increased in size and ultimately became juxtaposed with promyelocytic leukemia protein nuclear bodies. In normal fibroblasts, overexpression of wild-type Artemis increased radioresistance, while D165N overexpression conferred partial repair deficiency following high-dose radiation. Restoration of chemo/radioresistance by wild-type, but not D165N Artemis suggests that the lack of endonucleolytic trimming of DNA ends is the principal cause of sensitivity to double-strand cleaving agents in Artemis-deficient cells.
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Affiliation(s)
- Susovan Mohapatra
- Department of Pharmacology and Toxicology, Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
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Dobbs TA, Tainer JA, Lees-Miller SP. A structural model for regulation of NHEJ by DNA-PKcs autophosphorylation. DNA Repair (Amst) 2010; 9:1307-14. [PMID: 21030321 PMCID: PMC3045832 DOI: 10.1016/j.dnarep.2010.09.019] [Citation(s) in RCA: 162] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/30/2010] [Indexed: 11/22/2022]
Abstract
The DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and Ku heterodimer together form the biologically critical DNA-PK complex that plays key roles in the repair of ionizing radiation-induced DNA double-strand breaks through the non-homologous end-joining (NHEJ) pathway. Despite elegant and informative electron microscopy studies, the mechanism by which DNA-PK co-ordinates the initiation of NHEJ has been enigmatic due to limited structural information. Here, we discuss how the recently described small angle X-ray scattering structures of full-length Ku heterodimer and DNA-PKcs in solution, combined with a breakthrough DNA-PKcs crystal structure, provide significant insights into the early stages of NHEJ. Dynamic structural changes associated with a functionally important cluster of autophosphorylation sites play a significant role in regulating the dissociation of DNA-PKcs from Ku and DNA. These new structural insights have implications for understanding the formation and control of the DNA-PK synaptic complex, DNA-PKcs activation and initiation of NHEJ. More generally, they provide prototypic information for the phosphatidylinositol-3 kinase-like (PIKK) family of serine/threonine protein kinases that includes Ataxia Telangiectasia-Mutated (ATM) and ATM-, Rad3-related (ATR) as well as DNA-PKcs.
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Affiliation(s)
- Tracey A. Dobbs
- Departments of Biochemistry & Molecular Biology and Oncology, Southern Alberta Cancer Research Institute, University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta, Canada, T2N 4Z6
| | - John A. Tainer
- Department of Molecular Biology, Skaggs Institute of Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA and Life Sciences Division, Department of Molecular Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Susan P. Lees-Miller
- Departments of Biochemistry & Molecular Biology and Oncology, Southern Alberta Cancer Research Institute, University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta, Canada, T2N 4Z6
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Jacobs C, Huang Y, Masud T, Lu W, Westfield G, Giblin W, Sekiguchi JM. A hypomorphic Artemis human disease allele causes aberrant chromosomal rearrangements and tumorigenesis. Hum Mol Genet 2010; 20:806-19. [PMID: 21147755 DOI: 10.1093/hmg/ddq524] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The Artemis gene encodes a DNA nuclease that plays important roles in non-homologous end-joining (NHEJ), a major double-strand break (DSB) repair pathway in mammalian cells. NHEJ factors repair general DSBs as well as programmed breaks generated during the lymphoid-specific DNA rearrangement, V(D)J recombination, which is required for lymphocyte development. Mutations that inactivate Artemis cause a human severe combined immunodeficiency syndrome associated with cellular radiosensitivity. In contrast, hypomorphic Artemis mutations result in combined immunodeficiency syndromes of varying severity, but, in addition, are hypothesized to predispose to lymphoid malignancy. To elucidate the distinct molecular defects caused by hypomorphic compared with inactivating Artemis mutations, we examined tumor predisposition in a mouse model harboring a targeted partial loss-of-function disease allele. We find that, in contrast to Artemis nullizygosity, the hypomorphic mutation leads to increased aberrant intra- and interchromosomal V(D)J joining events. We also observe that dysfunctional Artemis activity combined with p53 inactivation predominantly predisposes to thymic lymphomas harboring clonal translocations distinct from those observed in Artemis nullizygosity. Thus, the Artemis hypomorphic allele results in unique molecular defects, tumor spectrum and oncogenic chromosomal rearrangements. Our findings have significant implications for disease outcomes and treatment of patients with different Artemis mutations.
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Affiliation(s)
- Cheryl Jacobs
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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Asaithamby A, Chen DJ. Mechanism of cluster DNA damage repair in response to high-atomic number and energy particles radiation. Mutat Res 2010; 711:87-99. [PMID: 21126526 DOI: 10.1016/j.mrfmmm.2010.11.002] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 10/29/2010] [Accepted: 11/23/2010] [Indexed: 02/07/2023]
Abstract
Low-linear energy transfer (LET) radiation (i.e., γ- and X-rays) induces DNA double-strand breaks (DSBs) that are rapidly repaired (rejoined). In contrast, DNA damage induced by the dense ionizing track of high-atomic number and energy (HZE) particles is slowly repaired or is irreparable. These unrepaired and/or misrepaired DNA lesions may contribute to the observed higher relative biological effectiveness for cell killing, chromosomal aberrations, mutagenesis, and carcinogenesis in HZE particle irradiated cells compared to those treated with low-LET radiation. The types of DNA lesions induced by HZE particles have been characterized in vitro and usually consist of two or more closely spaced strand breaks, abasic sites, or oxidized bases on opposing strands. It is unclear why these lesions are difficult to repair. In this review, we highlight the potential of a new technology allowing direct visualization of different types of DNA lesions in human cells and document the emerging significance of live-cell imaging for elucidation of the spatio-temporal characterization of complex DNA damage. We focus on the recent insights into the molecular pathways that participate in the repair of HZE particle-induced DSBs. We also discuss recent advances in our understanding of how different end-processing nucleases aid in repair of DSBs with complicated ends generated by HZE particles. Understanding the mechanism underlying the repair of DNA damage induced by HZE particles will have important implications for estimating the risks to human health associated with HZE particle exposure.
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Affiliation(s)
- Aroumougame Asaithamby
- Division of Molecular Radiation Biology, Department of Radiation Oncology, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, United States.
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Yan Y, Akhter S, Zhang X, Legerski R. The multifunctional SNM1 gene family: not just nucleases. Future Oncol 2010; 6:1015-29. [PMID: 20528238 DOI: 10.2217/fon.10.47] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The archetypical member of the SNM1 gene family was discovered 30 years ago in the budding yeast Saccharomyces cerevisiae. This small but ubiquitous gene family is characterized by metallo-beta-lactamase and beta-CASP domains, which together have been demonstrated to comprise a nuclease activity. Three mammalian members of this family, SNM1A, SNM1B/Apollo and Artemis, have been demonstrated to play surprisingly divergent roles in cellular metabolism. These pathways include variable (diversity) joining recombination, nonhomologous end-joining of double-strand breaks, DNA damage and mitotic cell cycle checkpoints, telomere maintenance and protein ubiquitination. Not all of these functions are consistent with a model in which these proteins act only as nucleases, and indicate that the SNM1 gene family encodes multifunctional products that can act in diverse biochemical pathways. In this article we discuss the various functions of SNM1A, SNM1B/Apollo and Artemis.
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Affiliation(s)
- Yiyi Yan
- Department of Genetics, University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
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Lamarche BJ, Orazio NI, Weitzman MD. The MRN complex in double-strand break repair and telomere maintenance. FEBS Lett 2010; 584:3682-95. [PMID: 20655309 DOI: 10.1016/j.febslet.2010.07.029] [Citation(s) in RCA: 301] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 07/16/2010] [Accepted: 07/19/2010] [Indexed: 10/25/2022]
Abstract
Genomes are subject to constant threat by damaging agents that generate DNA double-strand breaks (DSBs). The ends of linear chromosomes need to be protected from DNA damage recognition and end-joining, and this is achieved through protein-DNA complexes known as telomeres. The Mre11-Rad50-Nbs1 (MRN) complex plays important roles in detection and signaling of DSBs, as well as the repair pathways of homologous recombination (HR) and non-homologous end-joining (NHEJ). In addition, MRN associates with telomeres and contributes to their maintenance. Here, we provide an overview of MRN functions at DSBs, and examine its roles in telomere maintenance and dysfunction.
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Affiliation(s)
- Brandon J Lamarche
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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Pawelczak KS, Turchi JJ. Purification and characterization of exonuclease-free Artemis: Implications for DNA-PK-dependent processing of DNA termini in NHEJ-catalyzed DSB repair. DNA Repair (Amst) 2010; 9:670-7. [PMID: 20347402 DOI: 10.1016/j.dnarep.2010.03.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 02/12/2010] [Accepted: 03/01/2010] [Indexed: 11/24/2022]
Abstract
Artemis is a member of the beta-CASP family of nucleases in the metallo-beta-lactamase superfamily of hydrolases. Artemis has been demonstrated to be involved in V(D)J-recombination and in the NHEJ-catalyzed repair of DNA DSBs. In vitro, both DNA-PK independent 5'-3' exonuclease activities and DNA-PK dependent endonuclease activity have been attributed to Artemis, though mutational analysis of the Artemis active site only disrupts endonuclease activity. This suggests that either the enzyme contains two different active sites, or the exonuclease activity is not intrinsic to the Artemis polypeptide. To distinguish between these possibilities, we sought to determine if it was possible to biochemically separate Artemis endonuclease activity from exonuclease activity. Recombinant [His](6)-Artemis was expressed in a Baculovirus insect-cell expression system and isolated using a three-column purification methodology. Exonuclease and endonuclease activities, the ability to be phosphorylated by DNA-PK, and Artemis antibody reactivity was monitored throughout the purification and to characterize final pools of protein preparation. Results demonstrated the co-elution of exonuclease and endonuclease activities on a Ni-agarose affinity column but separation of the two enzymatic activities upon fractionation on a hydroxyapatite column. An exonuclease-free fraction of Artemis was obtained that retained DNA-PK dependent endonuclease activity, was phosphorylated by DNA-PK and reacted with an Artemis specific antibody. These data demonstrate that the exonuclease activity thought to be intrinsic to Artemis can be biochemically separated from the Artemis endonuclease.
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Affiliation(s)
- Katherine S Pawelczak
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46220, USA
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