1
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Vu DD, Bonucci A, Brenière M, Cisneros-Aguirre M, Pelupessy P, Wang Z, Carlier L, Bouvignies G, Cortes P, Aggarwal AK, Blackledge M, Gueroui Z, Belle V, Stark JM, Modesti M, Ferrage F. Multivalent interactions of the disordered regions of XLF and XRCC4 foster robust cellular NHEJ and drive the formation of ligation-boosting condensates in vitro. Nat Struct Mol Biol 2024:10.1038/s41594-024-01339-x. [PMID: 38898102 DOI: 10.1038/s41594-024-01339-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 05/28/2024] [Indexed: 06/21/2024]
Abstract
In mammalian cells, DNA double-strand breaks are predominantly repaired by non-homologous end joining (NHEJ). During repair, the Ku70-Ku80 heterodimer (Ku), X-ray repair cross complementing 4 (XRCC4) in complex with DNA ligase 4 (X4L4) and XRCC4-like factor (XLF) form a flexible scaffold that holds the broken DNA ends together. Insights into the architectural organization of the NHEJ scaffold and its regulation by the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) were recently obtained by single-particle cryo-electron microscopy analysis. However, several regions, especially the C-terminal regions (CTRs) of the XRCC4 and XLF scaffolding proteins, have largely remained unresolved in experimental structures, which hampers the understanding of their functions. Here we used magnetic resonance techniques and biochemical assays to comprehensively characterize the interactions and dynamics of the XRCC4 and XLF CTRs at residue resolution. We show that the CTRs of XRCC4 and XLF are intrinsically disordered and form a network of multivalent heterotypic and homotypic interactions that promotes robust cellular NHEJ activity. Importantly, we demonstrate that the multivalent interactions of these CTRs lead to the formation of XLF and X4L4 condensates in vitro, which can recruit relevant effectors and critically stimulate DNA end ligation. Our work highlights the role of disordered regions in the mechanism and dynamics of NHEJ and lays the groundwork for the investigation of NHEJ protein disorder and its associated condensates inside cells with implications in cancer biology, immunology and the development of genome-editing strategies.
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Affiliation(s)
- Duc-Duy Vu
- Département de Chimie, LBM, CNRS UMR 7203, École Normale Supérieure, PSL University, Sorbonne University, Paris, France
| | - Alessio Bonucci
- Aix Marseille Univ, CNRS UMR 7281, BIP Bioénergétique et Ingénierie des Protéines, IMM, Marseille, France
| | - Manon Brenière
- Cancer Research Center of Marseille, Department of Genome Integrity, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille University, Marseille, France
| | - Metztli Cisneros-Aguirre
- Department of Cancer Genetics and Epigenetics, Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, CA, USA
| | - Philippe Pelupessy
- Département de Chimie, LBM, CNRS UMR 7203, École Normale Supérieure, PSL University, Sorbonne University, Paris, France
| | - Ziqing Wang
- Département de Chimie, LBM, CNRS UMR 7203, École Normale Supérieure, PSL University, Sorbonne University, Paris, France
| | - Ludovic Carlier
- Département de Chimie, LBM, CNRS UMR 7203, École Normale Supérieure, PSL University, Sorbonne University, Paris, France
| | - Guillaume Bouvignies
- Département de Chimie, LBM, CNRS UMR 7203, École Normale Supérieure, PSL University, Sorbonne University, Paris, France
| | - Patricia Cortes
- Department of Molecular, Cellular and Biomedical Sciences, CUNY School of Medicine at City College of New York, New York, NY, USA
| | - Aneel K Aggarwal
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Martin Blackledge
- Institut de Biologie Structurale (IBS), Grenoble Alpes University, CNRS, CEA, Grenoble, France
| | - Zoher Gueroui
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne University, CNRS, Paris, France
| | - Valérie Belle
- Aix Marseille Univ, CNRS UMR 7281, BIP Bioénergétique et Ingénierie des Protéines, IMM, Marseille, France
| | - Jeremy M Stark
- Department of Cancer Genetics and Epigenetics, Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, CA, USA
| | - Mauro Modesti
- Cancer Research Center of Marseille, Department of Genome Integrity, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille University, Marseille, France.
| | - Fabien Ferrage
- Département de Chimie, LBM, CNRS UMR 7203, École Normale Supérieure, PSL University, Sorbonne University, Paris, France.
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2
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Marshall S, Navarro MV, Ascenҫão CF, Smolka MB. IN-DEPTH MAPPING OF DNA-PKcs SIGNALING UNCOVERS CONSERVED FEATURES OF ITS KINASE SPECIFICITY. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.17.576037. [PMID: 38293078 PMCID: PMC10827184 DOI: 10.1101/2024.01.17.576037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
DNA-PKcs is a DNA damage sensor kinase with established roles in DNA double-strand break repair via non-homologous end joining. Recent studies have revealed additional roles of DNA-PKcs in the regulation of transcription, translation and DNA replication. However, the substrates through which DNA-PKcs regulates these processes remain largely undefined. Here we utilized quantitative phosphoproteomics to generate a high coverage map of DNA-PKcs signaling in response to ionizing radiation and mapped its interplay with the ATM kinase. Beyond the detection of the canonical S/T-Q phosphorylation motif, we uncovered a non-canonical mode of DNA-PKcs signaling targeting S/T-ψ-D/E motifs. Cross-species analysis in mouse pre-B and human HCT116 cell lines revealed splicing factors and transcriptional regulators phosphorylated at this novel motif, several of which contain SAP domains. These findings expand the list of DNA-PKcs and ATM substrates and establish a novel preferential phosphorylation motif for DNA-PKcs that connects it to proteins involved in nucleotide processes and interactions.
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Affiliation(s)
- Shannon Marshall
- 1. Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Marcos V.A.S. Navarro
- 1. Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
- 2. IFSC Institute of Physics of São Carlos, University of São Paulo, São Carlos - SP, 13566-590, Brazil
| | - Carolline F.R. Ascenҫão
- 1. Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Marcus B. Smolka
- 1. Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
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3
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Xu J, Bradley N, He Y. Structure and function of the apical PIKKs in double-strand break repair. Curr Opin Struct Biol 2023; 82:102651. [PMID: 37437397 PMCID: PMC10530350 DOI: 10.1016/j.sbi.2023.102651] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 06/15/2023] [Accepted: 06/16/2023] [Indexed: 07/14/2023]
Abstract
Members of the phosphatidylinositol 3' kinase (PI3K)-related kinases (PIKKs) family, including DNA-dependent protein kinase catalytic subunit (DNA-PKcs), ataxia telangiectasia mutated (ATM), ataxia-telangiectasia mutated and Rad3-related (ATR), mammalian target of rapamycin (mTOR), suppressor with morphological effect on genitalia 1 (SMG1), and transformation/transcription domain-associated protein 1 (TRRAP/Tra1), participate in a variety of physiological processes, such as cell-cycle control, metabolism, transcription, replication, and the DNA damage response. In eukaryotic cells, DNA-PKcs, ATM, and ATR-ATRIP are the main sensors and regulators of DNA double-strand break repair. The purpose of this review is to describe recent structures of DNA-PKcs, ATM, and ATR, as well as their functions in activation and phosphorylation in different DNA repair pathways.
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Affiliation(s)
- Jingfei Xu
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Noah Bradley
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Yuan He
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA.
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4
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Chen S, Vogt A, Lee L, Naila T, McKeown R, Tomkinson AE, Lees-Miller SP, He Y. Cryo-EM visualization of DNA-PKcs structural intermediates in NHEJ. SCIENCE ADVANCES 2023; 9:eadg2838. [PMID: 37256947 PMCID: PMC10413680 DOI: 10.1126/sciadv.adg2838] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 04/28/2023] [Indexed: 06/02/2023]
Abstract
DNA double-strand breaks (DSBs), one of the most cytotoxic forms of DNA damage, can be repaired by the tightly regulated nonhomologous end joining (NHEJ) machinery (Stinson and Loparo and Zhao et al.). Core NHEJ factors form an initial long-range (LR) synaptic complex that transitions into a DNA-PKcs (DNA-dependent protein kinase, catalytic subunit)-free, short-range state to align the DSB ends (Chen et al.). Using single-particle cryo-electron microscopy, we have visualized three additional key NHEJ complexes representing different transition states, with DNA-PKcs adopting distinct dimeric conformations within each of them. Upon DNA-PKcs autophosphorylation, the LR complex undergoes a substantial conformational change, with both Ku and DNA-PKcs rotating outward to promote DNA break exposure and DNA-PKcs dissociation. We also captured a dimeric state of catalytically inactive DNA-PKcs, which resembles structures of other PIKK (Phosphatidylinositol 3-kinase-related kinase) family kinases, revealing a model of the full regulatory cycle of DNA-PKcs during NHEJ.
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Affiliation(s)
- Siyu Chen
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Interdisciplinary Biological Sciences Program, Northwestern University. Evanston, IL, USA
| | - Alex Vogt
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Interdisciplinary Biological Sciences Program, Northwestern University. Evanston, IL, USA
| | - Linda Lee
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre and Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Tasmin Naila
- Department of Internal Medicine and Molecular Genetics and Microbiology and the University of New Mexico Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM, USA
| | - Ryan McKeown
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Interdisciplinary Biological Sciences Program, Northwestern University. Evanston, IL, USA
| | - Alan E Tomkinson
- Department of Internal Medicine and Molecular Genetics and Microbiology and the University of New Mexico Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM, USA
| | - Susan P Lees-Miller
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre and Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Yuan He
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Interdisciplinary Biological Sciences Program, Northwestern University. Evanston, IL, USA
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, USA
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Northwestern University, Chicago, IL, USA
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5
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Nishikubo K, Hasegawa M, Izumi Y, Fujii K, Matsuo K, Matsumoto Y, Yokoya A. Structural study of wild-type and phospho-mimic XRCC4 dimer and multimer proteins using circular dichroism spectroscopy. Int J Radiat Biol 2023; 99:1684-1691. [PMID: 37171809 DOI: 10.1080/09553002.2023.2214210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 05/05/2023] [Indexed: 05/13/2023]
Abstract
PURPOSE To investigate the structural features of wild-type and phospho-mimicking mutated XRCC4 protein, a protein involved in DNA double-strand break repair. MATERIALS AND METHODS XRCC4 with a HisTag were expressed by E. coli harboring plasmid DNA and purified. Phospho-mimicking mutants in which one phosphorylation site was replaced with aspartic acid were also prepared in order to reproduce the negative charge resulting from phosphorylation. The proteins were separated into dimers and multimers by gel filtration chromatography. Circular dichroism (CD) spectroscopy was performed in the region from ultraviolet to vacuum-ultraviolet. The CD spectra were analyzed with two analysis programs to evaluate the secondary structures of the wild-type and phospho-mimicked dimers and multimers. RESULT AND DISCUSSION The proportion of β-strand in the wild-type dimers was very low, particularly in their C-terminal region, including the five phosphorylation sites. The secondary structure of the phospho-mimic hardly changed in the dimeric form. In contrast, the β-strand content increased and the α-helix content decreased upon multimerization of the wild-type protein. The structural change of multimers slightly depended on the phospho-mimic site. These results suggest that the β-strand structure stabilizes the multimerization of XRCC4 and it is regulated by phosphorylation at the C-terminal site in living cells. CONCLUSION An increase in the β-strand content in XRCC4 is essential for stabilization of the multimeric form through C-terminal phosphorylation, allowing the formation of the large double-strand break repair machinery.
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Affiliation(s)
- Kai Nishikubo
- Graduate School of Science and Engineering, Ibaraki University, Mito, Ibaraki, Japan
- Institute for Quantum Life Science, Quantum Life and Medical Science Directorate, National Institutes of Quantum Sciences and Technology (QST), Tokai, Ibaraki, Japan
| | - Maho Hasegawa
- Graduate School of Science and Engineering, Ibaraki University, Mito, Ibaraki, Japan
- Institute for Quantum Life Science, Quantum Life and Medical Science Directorate, National Institutes of Quantum Sciences and Technology (QST), Tokai, Ibaraki, Japan
| | - Yudai Izumi
- Institute for Quantum Life Science, Quantum Life and Medical Science Directorate, National Institutes of Quantum Sciences and Technology (QST), Tokai, Ibaraki, Japan
| | - Kentaro Fujii
- Institute for Quantum Life Science, Quantum Life and Medical Science Directorate, National Institutes of Quantum Sciences and Technology (QST), Tokai, Ibaraki, Japan
| | - Koichi Matsuo
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
| | - Yoshihisa Matsumoto
- Laboratory for Zero-Carbon Energy, Institute of Innovative Research, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan
| | - Akinari Yokoya
- Graduate School of Science and Engineering, Ibaraki University, Mito, Ibaraki, Japan
- Institute for Quantum Life Science, Quantum Life and Medical Science Directorate, National Institutes of Quantum Sciences and Technology (QST), Tokai, Ibaraki, Japan
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6
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Dylgjeri E, Knudsen KE. DNA-PKcs: A Targetable Protumorigenic Protein Kinase. Cancer Res 2022; 82:523-533. [PMID: 34893509 PMCID: PMC9306356 DOI: 10.1158/0008-5472.can-21-1756] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/17/2021] [Accepted: 11/10/2021] [Indexed: 01/07/2023]
Abstract
DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is a pleiotropic protein kinase that plays critical roles in cellular processes fundamental to cancer. DNA-PKcs expression and activity are frequently deregulated in multiple hematologic and solid tumors and have been tightly linked to poor outcome. Given the potentially influential role of DNA-PKcs in cancer development and progression, therapeutic targeting of this kinase is being tested in preclinical and clinical settings. This review summarizes the latest advances in the field, providing a comprehensive discussion of DNA-PKcs functions in cancer and an update on the clinical assessment of DNA-PK inhibitors in cancer therapy.
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Affiliation(s)
- Emanuela Dylgjeri
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania.,Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Karen E. Knudsen
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania.,Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania.,Department of Medical Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania.,Department of Urology, Thomas Jefferson University, Philadelphia, Pennsylvania.,Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania.,Corresponding Author: Karen E. Knudsen, Thomas Jefferson University, 233 South 10th Street, BLSB 1050, Philadelphia, PA 19107. Phone: 215-503-5692; E-mail:
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7
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WASH interacts with Ku to regulate DNA double-stranded break repair. iScience 2022; 25:103676. [PMID: 35036867 PMCID: PMC8749218 DOI: 10.1016/j.isci.2021.103676] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 06/12/2021] [Accepted: 12/20/2021] [Indexed: 12/28/2022] Open
Abstract
The Wiskott-Aldrich syndrome protein and SCAR homolog (WASH), an actin nucleation-promoting factor, is present in the nucleus where it regulates gene transcription and maintains nuclear organization. Here, we show that WASH interacts with core non-homologous end-joining (NHEJ) factors including Ku70/Ku80 and DNA-PKcs, and Ku70/Ku80 is involved in the recruitment of WASH to the sites of DNA double-stranded break (DSB). WASH depletion leads to increased cell sensitivity and impaired DNA repair capacity in response to etoposide-induced DSBs and reduces NHEJ efficiency. Mechanistically, we show that loss of WASH inhibits the phosphorylation of DNA-PKcs, H2AX, and KAP1 after DSB induction and reduces chromatin relaxation and the recruitment of several downstream NHEJ factors to DSBs. Moreover, WASH role in DSB repair depends on its conserved C-terminal VCA domain and Arp2/3 activation. Our findings reveal a function and mechanistic insight for WASH in DNA DSB repair by the NHEJ pathway.
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8
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Frock RL, Sadeghi C, Meng J, Wang JL. DNA End Joining: G0-ing to the Core. Biomolecules 2021; 11:biom11101487. [PMID: 34680120 PMCID: PMC8533500 DOI: 10.3390/biom11101487] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/05/2021] [Accepted: 10/06/2021] [Indexed: 12/28/2022] Open
Abstract
Humans have evolved a series of DNA double-strand break (DSB) repair pathways to efficiently and accurately rejoin nascently formed pairs of double-stranded DNA ends (DSEs). In G0/G1-phase cells, non-homologous end joining (NHEJ) and alternative end joining (A-EJ) operate to support covalent rejoining of DSEs. While NHEJ is predominantly utilized and collaborates extensively with the DNA damage response (DDR) to support pairing of DSEs, much less is known about A-EJ collaboration with DDR factors when NHEJ is absent. Non-cycling lymphocyte progenitor cells use NHEJ to complete V(D)J recombination of antigen receptor genes, initiated by the RAG1/2 endonuclease which holds its pair of targeted DSBs in a synapse until each specified pair of DSEs is handed off to the NHEJ DSB sensor complex, Ku. Similar to designer endonuclease DSBs, the absence of Ku allows for A-EJ to access RAG1/2 DSEs but with random pairing to complete their repair. Here, we describe recent insights into the major phases of DSB end joining, with an emphasis on synapsis and tethering mechanisms, and bring together new and old concepts of NHEJ vs. A-EJ and on RAG2-mediated repair pathway choice.
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9
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Matsumoto Y, Asa ADDC, Modak C, Shimada M. DNA-Dependent Protein Kinase Catalytic Subunit: The Sensor for DNA Double-Strand Breaks Structurally and Functionally Related to Ataxia Telangiectasia Mutated. Genes (Basel) 2021; 12:genes12081143. [PMID: 34440313 PMCID: PMC8394720 DOI: 10.3390/genes12081143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 07/19/2021] [Accepted: 07/22/2021] [Indexed: 11/16/2022] Open
Abstract
The DNA-dependent protein kinase (DNA-PK) is composed of a DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and Ku70/Ku80 heterodimer. DNA-PK is thought to act as the “sensor” for DNA double-stranded breaks (DSB), which are considered the most deleterious type of DNA damage. In particular, DNA-PKcs and Ku are shown to be essential for DSB repair through nonhomologous end joining (NHEJ). The phenotypes of animals and human individuals with defective DNA-PKcs or Ku functions indicate their essential roles in these developments, especially in neuronal and immune systems. DNA-PKcs are structurally related to Ataxia–telangiectasia mutated (ATM), which is also implicated in the cellular responses to DSBs. DNA-PKcs and ATM constitute the phosphatidylinositol 3-kinase-like kinases (PIKKs) family with several other molecules. Here, we review the accumulated knowledge on the functions of DNA-PKcs, mainly based on the phenotypes of DNA-PKcs-deficient cells in animals and human individuals, and also discuss its relationship with ATM in the maintenance of genomic stability.
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10
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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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11
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Asa ADDC, Wanotayan R, Sharma MK, Tsukada K, Shimada M, Matsumoto Y. Functional analysis of XRCC4 mutations in reported microcephaly and growth defect patients in terms of radiosensitivity. JOURNAL OF RADIATION RESEARCH 2021; 62:380-389. [PMID: 33842963 PMCID: PMC8127669 DOI: 10.1093/jrr/rrab016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 02/01/2021] [Indexed: 05/08/2023]
Abstract
Non-homologous end joining is one of the main pathways for DNA double-strand break (DSB) repair and is also implicated in V(D)J recombination in immune system. Therefore, mutations in non-homologous end-joining (NHEJ) proteins were found to be associated with immunodeficiency in human as well as in model animals. Several human patients with mutations in XRCC4 were reported to exhibit microcephaly and growth defects, but unexpectedly showed normal immune function. Here, to evaluate the functionality of these disease-associated mutations of XRCC4 in terms of radiosensitivity, we generated stable transfectants expressing these mutants in XRCC4-deficient murine M10 cells and measured their radiosensitivity by colony formation assay. V83_S105del, R225X and D254Mfs*68 were expressed at a similar level to wild-type XRCC4, while W43R, R161Q and R275X were expressed at even higher level than wild-type XRCC4. The expression levels of DNA ligase IV in the transfectants with these mutants were comparable to that in the wild-type XRCC4 transfectant. The V83S_S105del transfectant and, to a lesser extent, D254Mfs*68 transfectant, showed substantially increased radiosensitivity compared to the wild-type XRCC4 transfectant. The W43R, R161Q, R225X and R275X transfectants showed a slight but statistically significant increase in radiosensitivity compared to the wild-type XRCC4 transfectant. When expressed as fusion proteins with Green fluorescent protein (GFP), R225X, R275X and D254Mfs*68 localized to the cytoplasm, whereas other mutants localized to the nucleus. These results collectively indicated that the defects of XRCC4 in patients might be mainly due to insufficiency in protein quantity and impaired functionality, underscoring the importance of XRCC4's DSB repair function in normal development.
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Affiliation(s)
- Anie Day D C Asa
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, Tokyo 152-8550, Japan
| | - Rujira Wanotayan
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, Tokyo 152-8550, Japan
- Department of Radiological Technology, Mahidol University, Nakhon Pathom 73170, Thailand
| | - Mukesh Kumar Sharma
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, Tokyo 152-8550, Japan
- Department of Zoology, SPC Government College, Ajmer-305001, Rajasthan, India
| | - Kaima Tsukada
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, Tokyo 152-8550, Japan
| | - Mikio Shimada
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, Tokyo 152-8550, Japan
| | - Yoshihisa Matsumoto
- Corresponding author. Yoshihisa Matsumoto, Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 Japan. E-mail: ; FAX: +81-3-5734-3703
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12
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Güllülü Ö, Hehlgans S, Mayer BE, Gößner I, Petraki C, Hoffmann M, Dombrowsky MJ, Kunzmann P, Hamacher K, Strebhardt K, Fokas E, Rödel C, Münch C, Rödel F. A Spatial and Functional Interaction of a Heterotetramer Survivin-DNA-PKcs Complex in DNA Damage Response. Cancer Res 2021; 81:2304-2317. [PMID: 33408118 DOI: 10.1158/0008-5472.can-20-2931] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 11/19/2020] [Accepted: 12/28/2020] [Indexed: 11/16/2022]
Abstract
Substantial evidence has shown that overexpression of the inhibitor of apoptosis protein (IAP) survivin in human tumors correlates significantly with treatment resistance and poor patient prognosis. Survivin serves as a radiation resistance factor that impacts the DNA damage response by interacting with DNA-dependent protein kinase (DNA-PKcs). However, the complexity, molecular determinants, and functional consequences of this interrelationship remain largely unknown. By applying coimmunoprecipitation and flow cytometry-based Förster resonance energy transfer assays, we demonstrated a direct involvement of the survivin baculovirus IAP repeat domain in the regulation of radiation survival and DNA repair. This survivin-mediated activity required an interaction of residues S20 and W67 with the phosphoinositide 3-kinase (PI3K) domain of DNA-PKcs. In silico molecular docking and dynamics simulation analyses, in vitro kinase assays, and large-scale mass spectrometry suggested a heterotetrameric survivin-DNA-PKcs complex that results in a conformational change within the DNA-PKcs PI3K domain. Overexpression of survivin resulted in enhanced PI3K enzymatic activity and detection of differentially abundant phosphopeptides and proteins implicated in the DNA damage response. The survivin-DNA-PKcs interaction altered the S/T-hydrophobic motif substrate specificity of DNA-PKcs with a predominant usage of S/T-P phosphorylation sites and an increase of DNA-PKcs substrates including Foxo3. These data demonstrate that survivin differentially regulates DNA-PKcs-dependent radiation survival and DNA double-strand break repair via formation of a survivin-DNA-PKcs heterotetrameric complex. SIGNIFICANCE: These findings provide insight into survivin-mediated regulation of DNA-PKcs kinase and broaden our knowledge of the impact of survivin in modulating the cellular radiation response.See related commentary by Iliakis, p. 2270 GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/9/2304/F1.large.jpg.
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Affiliation(s)
- Ömer Güllülü
- Department of Radiotherapy and Oncology, University Hospital, Goethe University Frankfurt, Germany
| | - Stephanie Hehlgans
- Department of Radiotherapy and Oncology, University Hospital, Goethe University Frankfurt, Germany
| | - Benjamin E Mayer
- Department of Computational Biology and Simulation, Technical University of Darmstadt, Germany
| | - Ines Gößner
- Institute of Biochemistry II, Faculty of Medicine, Goethe University Frankfurt, Germany
| | - Chrysi Petraki
- Department of Radiotherapy and Oncology, University Hospital, Goethe University Frankfurt, Germany
| | - Melanie Hoffmann
- Department of Radiotherapy and Oncology, University Hospital, Goethe University Frankfurt, Germany
| | - Maximilian J Dombrowsky
- Department of Computational Biology and Simulation, Technical University of Darmstadt, Germany
| | - Patrick Kunzmann
- Department of Computational Biology and Simulation, Technical University of Darmstadt, Germany
| | - Kay Hamacher
- Department of Computational Biology and Simulation, Technical University of Darmstadt, Germany
| | - Klaus Strebhardt
- Department of Obstetrics and Gynaecology, University Hospital, Goethe University Frankfurt, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany.,German Cancer Consortium (DKTK) partner site: Frankfurt, Frankfurt am Main, Germany
| | - Emmanouil Fokas
- Department of Radiotherapy and Oncology, University Hospital, Goethe University Frankfurt, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany.,German Cancer Consortium (DKTK) partner site: Frankfurt, Frankfurt am Main, Germany.,Frankfurt Cancer Institute (FCI), Theodor-Stern-Kai 7, Goethe University Frankfurt, Germany
| | - Claus Rödel
- Department of Radiotherapy and Oncology, University Hospital, Goethe University Frankfurt, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany.,German Cancer Consortium (DKTK) partner site: Frankfurt, Frankfurt am Main, Germany.,Frankfurt Cancer Institute (FCI), Theodor-Stern-Kai 7, Goethe University Frankfurt, Germany
| | - Christian Münch
- Institute of Biochemistry II, Faculty of Medicine, Goethe University Frankfurt, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany.,German Cancer Consortium (DKTK) partner site: Frankfurt, Frankfurt am Main, Germany.,Frankfurt Cancer Institute (FCI), Theodor-Stern-Kai 7, Goethe University Frankfurt, Germany
| | - Franz Rödel
- Department of Radiotherapy and Oncology, University Hospital, Goethe University Frankfurt, Germany. .,German Cancer Research Center (DKFZ), Heidelberg, Germany.,German Cancer Consortium (DKTK) partner site: Frankfurt, Frankfurt am Main, Germany.,Frankfurt Cancer Institute (FCI), Theodor-Stern-Kai 7, Goethe University Frankfurt, Germany
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13
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Structural insights into the role of DNA-PK as a master regulator in NHEJ. GENOME INSTABILITY & DISEASE 2021; 2:195-210. [PMID: 34723130 PMCID: PMC8549938 DOI: 10.1007/s42764-021-00047-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 07/06/2021] [Accepted: 07/12/2021] [Indexed: 12/26/2022]
Abstract
DNA-dependent protein kinase catalytic subunit DNA-PKcs/PRKDC is the largest serine/threonine protein kinase of the phosphatidyl inositol 3-kinase-like protein kinase (PIKK) family and is the most highly expressed PIKK in human cells. With its DNA-binding partner Ku70/80, DNA-PKcs is required for regulated and efficient repair of ionizing radiation-induced DNA double-strand breaks via the non-homologous end joining (NHEJ) pathway. Loss of DNA-PKcs or other NHEJ factors leads to radiation sensitivity and unrepaired DNA double-strand breaks (DSBs), as well as defects in V(D)J recombination and immune defects. In this review, we highlight the contributions of the late Dr. Carl W. Anderson to the discovery and early characterization of DNA-PK. We furthermore build upon his foundational work to provide recent insights into the structure of NHEJ synaptic complexes, an evolutionarily conserved and functionally important YRPD motif, and the role of DNA-PKcs and its phosphorylation in NHEJ. The combined results identify DNA-PKcs as a master regulator that is activated by its detection of two double-strand DNA ends for a cascade of phosphorylation events that provide specificity and efficiency in assembling the synaptic complex for NHEJ.
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14
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González-Prieto R, Eifler-Olivi K, Claessens LA, Willemstein E, Xiao Z, Talavera Ormeno CMP, Ovaa H, Ulrich HD, Vertegaal ACO. Global non-covalent SUMO interaction networks reveal SUMO-dependent stabilization of the non-homologous end joining complex. Cell Rep 2021; 34:108691. [PMID: 33503430 DOI: 10.1016/j.celrep.2021.108691] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 12/11/2020] [Accepted: 01/05/2021] [Indexed: 12/17/2022] Open
Abstract
In contrast to our extensive knowledge on covalent small ubiquitin-like modifier (SUMO) target proteins, we are limited in our understanding of non-covalent SUMO-binding proteins. We identify interactors of different SUMO isoforms-monomeric SUMO1, monomeric SUMO2, or linear trimeric SUMO2 chains-using a mass spectrometry-based proteomics approach. We identify 379 proteins that bind to different SUMO isoforms, mainly in a preferential manner. Interestingly, XRCC4 is the only DNA repair protein in our screen with a preference for SUMO2 trimers over mono-SUMO2, as well as the only protein in our screen that belongs to the non-homologous end joining (NHEJ) DNA double-strand break repair pathway. A SUMO interaction motif (SIM) in XRCC4 regulates its recruitment to sites of DNA damage and phosphorylation of S320 by DNA-PKcs. Our data highlight the importance of non-covalent and covalent sumoylation for DNA double-strand break repair via the NHEJ pathway and provide a resource of SUMO isoform interactors.
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Affiliation(s)
- Román González-Prieto
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, the Netherlands.
| | - Karolin Eifler-Olivi
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, the Netherlands; Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz, Germany
| | - Laura A Claessens
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, the Netherlands
| | - Edwin Willemstein
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, the Netherlands
| | - Zhenyu Xiao
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, the Netherlands
| | - Cami M P Talavera Ormeno
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, the Netherlands; Oncode Institute, Einthovenweg 20, 2333 ZC Leiden, the Netherlands
| | - Huib Ovaa
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, the Netherlands; Oncode Institute, Einthovenweg 20, 2333 ZC Leiden, the Netherlands
| | - Helle D Ulrich
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz, Germany
| | - Alfred C O Vertegaal
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, the Netherlands.
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15
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Anisenko A, Kan M, Shadrina O, Brattseva A, Gottikh M. Phosphorylation Targets of DNA-PK and Their Role in HIV-1 Replication. Cells 2020; 9:E1907. [PMID: 32824372 PMCID: PMC7464883 DOI: 10.3390/cells9081907] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 08/13/2020] [Accepted: 08/14/2020] [Indexed: 02/07/2023] Open
Abstract
The DNA dependent protein kinase (DNA-PK) is a trimeric nuclear complex consisting of a large protein kinase and the Ku heterodimer. The kinase activity of DNA-PK is required for efficient repair of DNA double-strand breaks (DSB) by non-homologous end joining (NHEJ). We also showed that the kinase activity of DNA-PK is essential for post-integrational DNA repair in the case of HIV-1 infection. Besides, DNA-PK is known to participate in such cellular processes as protection of mammalian telomeres, transcription, and some others where the need for its phosphorylating activity is not clearly elucidated. We carried out a systematic search and analysis of DNA-PK targets described in the literature and identified 67 unique DNA-PK targets phosphorylated in response to various in vitro and/or in vivo stimuli. A functional enrichment analysis of DNA-PK targets and determination of protein-protein associations among them were performed. For 27 proteins from these 67 DNA-PK targets, their participation in the HIV-1 life cycle was demonstrated. This information may be useful for studying the functioning of DNA-PK in various cellular processes, as well as in various stages of HIV-1 replication.
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Affiliation(s)
- Andrey Anisenko
- Chemistry Department and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia; (O.S.); (M.G.)
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia;; (M.K.); (A.B.)
| | - Marina Kan
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia;; (M.K.); (A.B.)
| | - Olga Shadrina
- Chemistry Department and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia; (O.S.); (M.G.)
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia;; (M.K.); (A.B.)
| | - Anna Brattseva
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia;; (M.K.); (A.B.)
| | - Marina Gottikh
- Chemistry Department and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia; (O.S.); (M.G.)
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16
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Improving Precise CRISPR Genome Editing by Small Molecules: Is there a Magic Potion? Cells 2020; 9:cells9051318. [PMID: 32466303 PMCID: PMC7291049 DOI: 10.3390/cells9051318] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 05/18/2020] [Accepted: 05/19/2020] [Indexed: 01/01/2023] Open
Abstract
Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) genome editing has become a standard method in molecular biology, for the establishment of genetically modified cellular and animal models, for the identification and validation of drug targets in animals, and is heavily tested for use in gene therapy of humans. While the efficiency of CRISPR mediated gene targeting is much higher than of classical targeted mutagenesis, the efficiency of CRISPR genome editing to introduce defined changes into the genome is still low. Overcoming this problem will have a great impact on the use of CRISPR genome editing in academic and industrial research and the clinic. This review will present efforts to achieve this goal by small molecules, which modify the DNA repair mechanisms to facilitate the precise alteration of the genome.
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17
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Amiri Moghani AR, Sharma MK, Matsumoto Y. In cellulo phosphorylation of DNA double-strand break repair protein XRCC4 on Ser260 by DNA-PK. JOURNAL OF RADIATION RESEARCH 2018; 59:700-708. [PMID: 30247612 PMCID: PMC6251426 DOI: 10.1093/jrr/rry072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Indexed: 05/16/2023]
Abstract
XRCC4 is one of the core factors for DNA double-strand break (DSB) repair through non-homologous end joining (NHEJ). XRCC4 is phosphorylated by DNA-dependent protein kinase (DNA-PK), with Ser260 and Ser320 (Ser318 in the alternatively spliced form) being the major phosphorylation sites in vitro. It was recently reported that Ser320 is phosphorylated by DNA-PK in response to DNA damage; however, it is currently unclear whether Ser260 is phosphorylated in cellulo in response to DNA damage. Herein, we generated an antibody against XRCC4 phosphorylated on Ser260 and examined its phosphorylation status via Western blotting. XRCC4 Ser260 phosphorylation increased after irradiation with 30-300 Gy of γ-rays and was suppressed by DNA-PK inhibitor but not by ATM inhibitor. Moreover, XRCC4 Ser260 phosphorylation decreased in DNA-PKcs-deficient cells. These observations indicate that XRCC4 Ser260 is phosphorylated by DNA-PK in cellulo. The XRCC4S260A mutant reversed the high radiosensitivity of XRCC4-deficient M10 cells to a similar level to that of wild-type XRCC4. However, the clonogenic survival of cells expressing the XRCC4S260A mutant was slightly but significantly lower than that of those expressing wild-type XRCC4. In addition, XRCC4S260A-expressing cells displayed a significantly greater number of γ-H2AX foci than XRCC4WT-expressing cells 4 h after 1 Gy irradiation and without irradiation. The present results suggest a potential role of XRCC4 Ser260 phosphorylation by DNA-PK in DSB repair.
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Affiliation(s)
- Ali Reza Amiri Moghani
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1-N1–30, Ookayama, Meguro-ku, Tokyo, Japan
| | - Mukesh Kumar Sharma
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1-N1–30, Ookayama, Meguro-ku, Tokyo, Japan
- Department of Zoology, SPC Government College, Ajmer, Rajasthan, India
| | - Yoshihisa Matsumoto
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1-N1–30, Ookayama, Meguro-ku, Tokyo, Japan
- Corresponding author. Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1-N1–30, Ookayama, Meguro-ku, Tokyo 152-8550, Japan. Tel/Fax: +81-0-3-5734-3703;
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18
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Normanno D, Négrel A, de Melo AJ, Betzi S, Meek K, Modesti M. Mutational phospho-mimicry reveals a regulatory role for the XRCC4 and XLF C-terminal tails in modulating DNA bridging during classical non-homologous end joining. eLife 2017; 6. [PMID: 28500754 PMCID: PMC5468090 DOI: 10.7554/elife.22900] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 05/12/2017] [Indexed: 12/23/2022] Open
Abstract
XRCC4 and DNA Ligase 4 (LIG4) form a tight complex that provides DNA ligase activity for classical non-homologous end joining (the predominant DNA double-strand break repair pathway in higher eukaryotes) and is stimulated by XLF. Independently of LIG4, XLF also associates with XRCC4 to form filaments that bridge DNA. These XRCC4/XLF complexes rapidly load and connect broken DNA, thereby stimulating intermolecular ligation. XRCC4 and XLF both include disordered C-terminal tails that are functionally dispensable in isolation but are phosphorylated in response to DNA damage by DNA-PK and/or ATM. Here we concomitantly modify the tails of XRCC4 and XLF by substituting fourteen previously identified phosphorylation sites with either alanine or aspartate residues. These phospho-blocking and -mimicking mutations impact both the stability and DNA bridging capacity of XRCC4/XLF complexes, but without affecting their ability to stimulate LIG4 activity. Implicit in this finding is that phosphorylation may regulate DNA bridging by XRCC4/XLF filaments.
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Affiliation(s)
- Davide Normanno
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université UM105, Marseille, France
| | - Aurélie Négrel
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université UM105, Marseille, France
| | - Abinadabe J de Melo
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université UM105, Marseille, France
| | - Stéphane Betzi
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université UM105, Marseille, France
| | - Katheryn Meek
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, United States.,Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, United States
| | - Mauro Modesti
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université UM105, Marseille, France
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19
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Sastre-Moreno G, Pryor JM, Moreno-Oñate M, Herrero-Ruiz AM, Cortés-Ledesma F, Blanco L, Ramsden DA, Ruiz JF. Regulation of human polλ by ATM-mediated phosphorylation during non-homologous end joining. DNA Repair (Amst) 2017; 51:31-45. [PMID: 28109743 DOI: 10.1016/j.dnarep.2017.01.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 01/05/2017] [Accepted: 01/09/2017] [Indexed: 11/26/2022]
Abstract
DNA double strand breaks (DSBs) trigger a variety of cellular signaling processes, collectively termed the DNA-damage response (DDR), that are primarily regulated by protein kinase ataxia-telangiectasia mutated (ATM). Among DDR activated processes, the repair of DSBs by non-homologous end joining (NHEJ) is essential. The proper coordination of NHEJ factors is mainly achieved through phosphorylation by an ATM-related kinase, the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), although the molecular basis for this regulation has yet to be fully elucidated. In this study we identify the major NHEJ DNA polymerase, DNA polymerase lambda (Polλ), as a target for both ATM and DNA-PKcs in human cells. We show that Polλ is efficiently phosphorylated by DNA-PKcs in vitro and predominantly by ATM after DSB induction with ionizing radiation (IR) in vivo. We identify threonine 204 (T204) as a main target for ATM/DNA-PKcs phosphorylation on human Polλ, and establish that its phosphorylation may facilitate the repair of a subset of IR-induced DSBs and the efficient Polλ-mediated gap-filling during NHEJ. Molecular evidence suggests that Polλ phosphorylation might favor Polλ interaction with the DNA-PK complex at DSBs. Altogether, our work provides the first demonstration of how Polλ is regulated by phosphorylation to connect with the NHEJ core machinery during DSB repair in human cells.
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Affiliation(s)
- Guillermo Sastre-Moreno
- Centro de Biología Molecular "Severo Ochoa", Universidad Autónoma de Madrid/CSIC, Madrid 28049, Spain
| | - John M Pryor
- Department of Biochemistry and Biophysics and Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Marta Moreno-Oñate
- Departamento Bioquímica Vegetal y Biología Molecular, Universidad de Sevilla, Sevilla 41092, Spain; Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla/CSIC, Sevilla 41092, Spain
| | - Andrés M Herrero-Ruiz
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla/CSIC, Sevilla 41092, Spain
| | - Felipe Cortés-Ledesma
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla/CSIC, Sevilla 41092, Spain
| | - Luis Blanco
- Centro de Biología Molecular "Severo Ochoa", Universidad Autónoma de Madrid/CSIC, Madrid 28049, Spain
| | - Dale A Ramsden
- Department of Biochemistry and Biophysics and Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jose F Ruiz
- Departamento Bioquímica Vegetal y Biología Molecular, Universidad de Sevilla, Sevilla 41092, Spain; Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla/CSIC, Sevilla 41092, Spain.
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20
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Regulation of non-homologous end joining via post-translational modifications of components of the ligation step. Curr Genet 2016; 63:591-605. [PMID: 27915381 DOI: 10.1007/s00294-016-0670-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 11/25/2016] [Accepted: 11/26/2016] [Indexed: 12/29/2022]
Abstract
DNA double-strand breaks are the most serious type of DNA damage and non-homologous end joining (NHEJ) is an important pathway for their repair. In Saccharomyces cerevisiae, three complexes mediate the canonical NHEJ pathway, Ku (Ku70/Ku80), MRX (Mre11/Rad50/Xrs2) and DNA ligase IV (Dnl4/Lif1). Mammalian NHEJ is more complex, primarily as a consequence of the fact that more factors are involved in the process, and also because higher chromatin organization and more complex regulatory networks exist in mammals. In addition, a stronger interconnection between the NHEJ and DNA damage response (DDR) pathways seems to occur in mammals compared to yeast. DDR employs multiple post-translational modifications (PTMs) of the target proteins and mutual crosstalk among them to ensure highly efficient down-stream effects. Checkpoint-mediated phosphorylation is the best understood PTM that regulates DDR, although recently SUMOylation has also been shown to be involved. Both phosphorylation and SUMOylation affect components of NHEJ. In this review, we discuss a role of these two PTMs in regulation of NHEJ via targeting the components of the ligation step.
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21
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Koike M, Yutoku Y, Koike A. Cloning, localization and focus formation at DNA damage sites of canine XRCC4. J Vet Med Sci 2016; 78:1865-1871. [PMID: 27644316 PMCID: PMC5240766 DOI: 10.1292/jvms.16-0381] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Various chemotherapies and radiation therapies are useful for killing cancer cells mainly by inducing DNA double-strand breaks (DSBs). Uncovering the molecular mechanisms of DSB repair processes is crucial for developing next-generation radiotherapies and chemotherapeutics for human and animal cancers. XRCC4 plays a critical role in Ku-dependent nonhomologous DNA-end joining (NHEJ) in human cells, and is one of the core NHEJ factors. The localization of core NHEJ factors, such as human Ku70 and Ku80, might play a crucial role in regulating NHEJ activity. Recently, companion animals, such as canines, have been proposed to be a good model in many aspects of cancer research. However, the localization and regulation mechanisms of core NHEJ factors in canine cells have not been elucidated. Here, we show that the expression and subcellular localization of canine XRCC4 changes dynamically during the cell cycle. Furthermore, EYFP-canine XRCC4 accumulates quickly at laser-microirradiated DSB sites. The structure of a putative human XRCC4 nuclear localization signal (NLS) is highly conserved in canine, chimpanzee and mouse XRCC4. However, the amino acid residue corresponding to the human XRCC4 K210, thought to be important for nuclear localization, is not conserved in canine XRCC4. Our findings might be useful for the study of the molecular mechanisms of Ku-dependent NHEJ in canine cells and the development of new radiosensitizers that target XRCC4.
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Affiliation(s)
- Manabu Koike
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
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22
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Meek K, Xu Y, Bailie C, Yu K, Neal JA. The ATM Kinase Restrains Joining of Both VDJ Signal and Coding Ends. THE JOURNAL OF IMMUNOLOGY 2016; 197:3165-3174. [PMID: 27574300 DOI: 10.4049/jimmunol.1600597] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 08/06/2016] [Indexed: 11/19/2022]
Abstract
The evidence that ATM affects resolution of RAG-induced DNA double-strand breaks is profuse and unequivocal; moreover, it is clear that the RAG complex itself cooperates (in an undetermined way) with ATM to facilitate repair of these double-strand breaks by the classical nonhomologous end-joining pathway. The mechanistic basis for the cooperation between ATM and the RAG complex has not been defined, although proposed models invoke ATM and RAG2's C terminus in maintaining the RAG postcleavage complex. In this study, we show that ATM reduces the rate of both coding and signal joining in a robust episomal assay; we suggest that this is the result of increased stability of the postcleavage complex. ATM's ability to inhibit VDJ joining requires its enzymatic activity. The noncore C termini of both RAG1 and RAG2 are also required for ATM's capacity to limit signal (but not coding) joining. Moreover, potential phosphorylation targets within the C terminus of RAG2 are also required for ATM's capacity to limit signal joining. These data suggest a model whereby the RAG signal end complex is stabilized by phosphorylation of RAG2 by ATM.
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Affiliation(s)
- Katheryn Meek
- Department of Microbiology and Molecular Genetics, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824; .,Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824; and
| | - Yao Xu
- Department of Microbiology and Molecular Genetics, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824.,Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824; and
| | - Caleb Bailie
- Department of Microbiology and Molecular Genetics, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824.,Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824; and
| | - Kefei Yu
- Department of Microbiology and Molecular Genetics, College of Human Medicine, Michigan State University, East Lansing, MI 48824
| | - Jessica A Neal
- Department of Microbiology and Molecular Genetics, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824.,Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824; and
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Sharma MK, Imamichi S, Fukuchi M, Samarth RM, Tomita M, Matsumoto Y. In cellulo phosphorylation of XRCC4 Ser320 by DNA-PK induced by DNA damage. JOURNAL OF RADIATION RESEARCH 2016; 57:115-20. [PMID: 26666690 PMCID: PMC4795952 DOI: 10.1093/jrr/rrv086] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 10/14/2015] [Accepted: 10/25/2015] [Indexed: 05/24/2023]
Abstract
XRCC4 is a protein associated with DNA Ligase IV, which is thought to join two DNA ends at the final step of DNA double-strand break repair through non-homologous end joining. In response to treatment with ionizing radiation or DNA damaging agents, XRCC4 undergoes DNA-PK-dependent phosphorylation. Furthermore, Ser260 and Ser320 (or Ser318 in alternatively spliced form) of XRCC4 were identified as the major phosphorylation sites by purified DNA-PK in vitro through mass spectrometry. However, it has not been clear whether these sites are phosphorylated in vivo in response to DNA damage. In the present study, we generated an antibody that reacts with XRCC4 phosphorylated at Ser320 and examined in cellulo phosphorylation status of XRCC4 Ser320. The phosphorylation of XRCC4 Ser320 was induced by γ-ray irradiation and treatment with Zeocin. The phosphorylation of XRCC4 Ser320 was detected even after 1 Gy irradiation and increased in a manner dependent on radiation dose. The phosphorylation was observed immediately after irradiation and remained mostly unchanged for up to 4 h. The phosphorylation was inhibited by DNA-PK inhibitor NU7441 and was undetectable in DNA-PKcs-deficient cells, indicating that the phosphorylation was mainly mediated by DNA-PK. These results suggested potential usefulness of the phosphorylation status of XRCC4 Ser320 as an indicator of DNA-PK functionality in living cells.
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Affiliation(s)
- Mukesh Kumar Sharma
- Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, N1-30 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550, Japan Department of Zoology, R.R. Government College, Alwar 301001, India
| | - Shoji Imamichi
- Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, N1-30 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550, Japan Division of Chemotherapy and Clinical Research, National Cancer Center Research Institute, Tokyo 104-0045, Japan
| | - Mikoto Fukuchi
- Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, N1-30 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Ravindra Mahadeo Samarth
- Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, N1-30 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550, Japan Department of Research, Bhopal Memorial Hospital & Research Centre, Department of Health Research, Raisen Bypass Road, Bhopal 462038, India National Institute for Research in Environmental Health, Indian Council of Medical Research, Kamla Nehru Hospital Building, Gandhi Medical College Campus, Bhopal 462001, India
| | - Masanori Tomita
- Radiation Safety Research Center, Central Research Institute of Electric Power Industry, Tokyo 201-8511, Japan
| | - Yoshihisa Matsumoto
- Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, N1-30 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550, Japan
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FBXW7 Facilitates Nonhomologous End-Joining via K63-Linked Polyubiquitylation of XRCC4. Mol Cell 2016; 61:419-433. [PMID: 26774286 DOI: 10.1016/j.molcel.2015.12.010] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 10/05/2015] [Accepted: 12/02/2015] [Indexed: 11/22/2022]
Abstract
FBXW7 is a haploinsufficient tumor suppressor with loss-of-function mutations occurring in human cancers. FBXW7 inactivation causes genomic instability, but the mechanism remains elusive. Here we show that FBXW7 facilitates nonhomologous end-joining (NHEJ) repair and that FBXW7 depletion causes radiosensitization. In response to ionizing radiation, ATM phosphorylates FBXW7 at serine 26 to recruit it to DNA double-strand break (DSB) sites, whereas activated DNA-PKcs phosphorylates XRCC4 at serines 325/326, which promotes binding of XRCC4 to FBXW7. SCF(FBXW7) E3 ligase then promotes polyubiquitylation of XRCC4 at lysine 296 via lysine 63 linkage for enhanced association with the Ku70/80 complex to facilitate NHEJ repair. Consistent with these findings, a small-molecule inhibitor that abrogates XRCC4 polyubiquitylation reduces NHEJ repair. Our study demonstrates one mechanism by which FBXW7 contributes to genome integrity and implies that inactivated FBXW7 in human cancers could be a strategy for increasing the efficacy of radiotherapy.
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Quantification of XRCC and DNA-PK proteins in cancer cell lines and human tumors by LC-MS/MS. Bioanalysis 2015; 6:2969-83. [PMID: 24785829 DOI: 10.4155/bio.14.121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND The x-ray repair cross-complementing (XRCC) proteins and a catalytic subunit of nuclear DNA-dependent serine/threonine protein kinase (DNA-PK) play important roles in cancer biology. Understanding the protein expression levels allows us to reconstruct in vivo functionality and to qualify protein biomarkers. METHODS & RESULTS XRCC and DNA-PK proteins in human cancer cells and tumor tissues have been identified and quantified by selected peptides using NanoLC and high-resolution mass spectrometry. The stable isotope-labeled full-length protein XRCC4 ([(13)C6, (15)N4]-arginine and [(13)C6, (15)N2]-lysine) uses as the internal standard. CONCLUSION The assay range is 0.140-450 fmol (coefficient of variation: 25%) for XRCC4 in bovine serum albumen. The quantitative protein expression levels for XRCC and DNA-PK in HeLa, Ramos and HEK-293 cells and tumor tissues (lung and lymphoma) are reported.
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Wanotayan R, Fukuchi M, Imamichi S, Sharma MK, Matsumoto Y. Asparagine 326 in the extremely C-terminal region of XRCC4 is essential for the cell survival after irradiation. Biochem Biophys Res Commun 2015; 457:526-31. [PMID: 25597996 DOI: 10.1016/j.bbrc.2015.01.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 01/07/2015] [Indexed: 12/25/2022]
Abstract
XRCC4 is one of the crucial proteins in the repair of DNA double-strand break (DSB) through non-homologous end-joining (NHEJ). As XRCC4 consists of 336 amino acids, N-terminal 200 amino acids include domains for dimerization and for association with DNA ligase IV and XLF and shown to be essential for XRCC4 function in DSB repair and V(D)J recombination. On the other hand, the role of the remaining C-terminal region of XRCC4 is not well understood. In the present study, we noticed that a stretch of ∼20 amino acids located at the extreme C-terminus of XRCC4 is highly conserved among vertebrate species. To explore its possible importance, series of mutants in this region were constructed and assessed for the functionality in terms of ability to rescue radiosensitivity of M10 cells lacking XRCC4. Among 13 mutants, M10 transfectant with N326L mutant (M10-XRCC4(N326L)) showed elevated radiosensitivity. N326L protein showed defective nuclear localization. N326L sequence matched the consensus sequence of nuclear export signal. Leptomycin B treatment accumulated XRCC4(N326L) in the nucleus but only partially rescued radiosensitivity of M10-XRCC4(N326L). These results collectively indicated that the functional defects of XRCC4(N326L) might be partially, but not solely, due to its exclusion from nucleus by synthetic nuclear export signal. Further mutation of XRCC4 Asn326 to other amino acids, i.e., alanine, aspartic acid or glutamine did not affect the nuclear localization but still exhibited radiosensitivity. The present results indicated the importance of the extremely C-terminal region of XRCC4 and, especially, Asn326 therein.
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Affiliation(s)
- Rujira Wanotayan
- Research Laboratory for Nuclear Reactors and Department of Nuclear Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8550, Japan
| | - Mikoto Fukuchi
- Research Laboratory for Nuclear Reactors and Department of Nuclear Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8550, Japan
| | - Shoji Imamichi
- Research Laboratory for Nuclear Reactors and Department of Nuclear Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8550, Japan
| | - Mukesh Kumar Sharma
- Research Laboratory for Nuclear Reactors and Department of Nuclear Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8550, Japan
| | - Yoshihisa Matsumoto
- Research Laboratory for Nuclear Reactors and Department of Nuclear Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8550, Japan.
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The DNA-dependent protein kinase: A multifunctional protein kinase with roles in DNA double strand break repair and mitosis. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 117:194-205. [PMID: 25550082 DOI: 10.1016/j.pbiomolbio.2014.12.003] [Citation(s) in RCA: 194] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 12/16/2014] [Accepted: 12/19/2014] [Indexed: 11/21/2022]
Abstract
The DNA-dependent protein kinase (DNA-PK) is a serine/threonine protein kinase composed of a large catalytic subunit (DNA-PKcs) and the Ku70/80 heterodimer. Over the past two decades, significant progress has been made in elucidating the role of DNA-PK in non-homologous end joining (NHEJ), the major pathway for repair of ionizing radiation-induced DNA double strand breaks in human cells and recently, additional roles for DNA-PK have been reported. In this review, we will describe the biochemistry, structure and function of DNA-PK, its roles in DNA double strand break repair and its newly described roles in mitosis and other cellular processes.
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The Ku heterodimer: function in DNA repair and beyond. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2014; 763:15-29. [PMID: 25795113 DOI: 10.1016/j.mrrev.2014.06.002] [Citation(s) in RCA: 185] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 06/07/2014] [Accepted: 06/25/2014] [Indexed: 01/11/2023]
Abstract
Ku is an abundant, highly conserved DNA binding protein found in both prokaryotes and eukaryotes that plays essential roles in the maintenance of genome integrity. In eukaryotes, Ku is a heterodimer comprised of two subunits, Ku70 and Ku80, that is best characterized for its central role as the initial DNA end binding factor in the "classical" non-homologous end joining (C-NHEJ) pathway, the main DNA double-strand break (DSB) repair pathway in mammals. Ku binds double-stranded DNA ends with high affinity in a sequence-independent manner through a central ring formed by the intertwined strands of the Ku70 and Ku80 subunits. At the break, Ku directly and indirectly interacts with several C-NHEJ factors and processing enzymes, serving as the scaffold for the entire DNA repair complex. There is also evidence that Ku is involved in signaling to the DNA damage response (DDR) machinery to modulate the activation of cell cycle checkpoints and the activation of apoptosis. Interestingly, Ku is also associated with telomeres, where, paradoxically to its DNA end-joining functions, it protects the telomere ends from being recognized as DSBs, thereby preventing their recombination and degradation. Ku, together with the silent information regulator (Sir) complex is also required for transcriptional silencing through telomere position effect (TPE). How Ku associates with telomeres, whether it is through direct DNA binding, or through protein-protein interactions with other telomere bound factors remains to be determined. Ku is central to the protection of organisms through its participation in C-NHEJ to repair DSBs generated during V(D)J recombination, a process that is indispensable for the establishment of the immune response. Ku also functions to prevent tumorigenesis and senescence since Ku-deficient mice show increased cancer incidence and early onset of aging. Overall, Ku function is critical to the maintenance of genomic integrity and to proper cellular and organismal development.
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Francis DB, Kozlov M, Chavez J, Chu J, Malu S, Hanna M, Cortes P. DNA Ligase IV regulates XRCC4 nuclear localization. DNA Repair (Amst) 2014; 21:36-42. [PMID: 24984242 DOI: 10.1016/j.dnarep.2014.05.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 05/22/2014] [Accepted: 05/29/2014] [Indexed: 11/17/2022]
Abstract
DNA Ligase IV, along with its interacting partner XRCC4, are essential for repairing DNA double strand breaks by non-homologous end joining (NHEJ). Together, they complete the final ligation step resolving the DNA break. Ligase IV is regulated by XRCC4 and XLF. However, the mechanism(s) by which Ligase IV control the NHEJ reaction and other NHEJ factor(s) remains poorly characterized. Here, we show that a C-terminal region of Ligase IV (aa 620-800), which encompasses a NLS, the BRCT I, and the XRCC4 interacting region (XIR), is essential for nuclear localization of its co-factor XRCC4. In Ligase IV deficient cells, XRCC4 showed deregulated localization remaining in the cytosol even after induction of DNA double strand breaks. DNA Ligase IV was also required for efficient localization of XLF into the nucleus. Additionally, human fibroblasts that harbor hypomorphic mutations within the Ligase IV gene displayed decreased levels of XRCC4 protein, implicating that DNA Ligase IV is also regulating XRCC4 stability. Our results provide evidence for a role of DNA Ligase IV in controlling the cellular localization and protein levels of XRCC4.
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Affiliation(s)
- Dailia B Francis
- Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Graduate School of Biological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Mikhail Kozlov
- Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Jose Chavez
- Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Jennifer Chu
- Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Shruti Malu
- Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Mary Hanna
- Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Patricia Cortes
- Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Graduate School of Biological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States.
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30
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Cytotoxic autophagy in cancer therapy. Int J Mol Sci 2014; 15:10034-51. [PMID: 24905404 PMCID: PMC4100138 DOI: 10.3390/ijms150610034] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 04/17/2014] [Accepted: 05/19/2014] [Indexed: 01/01/2023] Open
Abstract
Autophagy is a process of cellular self-digestion, whereby the cell degrades subcellular materials in order to generate energy and metabolic precursors in order to prolong survival, classically under conditions of nutrient deprivation. Autophagy can also involve the degradation of damaged or aged organelles, and misfolded or damaged proteins to eliminate these components that might otherwise be deleterious to cellular survival. Consequently, autophagy has generally been considered a prosurvival response. Many, if not most chemotherapeutic drugs and radiation also promote autophagy, which is generally considered a cytoprotective response, in that its inhibition frequently promotes apoptotic cells death. Furthermore, it has been shown that conventional chemotherapeutic drugs and radiation alone rarely induce a form of autophagy that leads to cell death. However, there are multiple examples in the literature where newer chemotherapeutic agents, drug combinations or drugs in combination with radiation promote autophagic cell death. This review will describe autophagic cell death induced in breast tumor cells, lung cancer cells as well as glioblastoma, demonstrating that it cannot be concluded that stress induced autophagy is, of necessity, cytoprotective in function.
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Genome-wide screens for sensitivity to ionizing radiation identify the fission yeast nonhomologous end joining factor Xrc4. G3-GENES GENOMES GENETICS 2014; 4:1297-306. [PMID: 24847916 PMCID: PMC4455778 DOI: 10.1534/g3.114.011841] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Nonhomologous end joining (NHEJ) is the main means for repairing DNA double-strand breaks (DSBs) in human cells. Molecular understanding of NHEJ has benefited from analyses in the budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe. In human cells, the DNA ligation reaction of the classical NHEJ pathway is carried out by a protein complex composed of DNA ligase IV (LigIV) and XRCC4. In S. cerevisiae, this reaction is catalyzed by a homologous complex composed of Dnl4 and Lif1. Intriguingly, no homolog of XRCC4 has been found in S. pombe, raising the possibility that such a factor may not always be required for classical NHEJ. Here, through screening the ionizing radiation (IR) sensitivity phenotype of a genome-wide fission yeast deletion collection in both the vegetative growth state and the spore state, we identify Xrc4, a highly divergent homolog of human XRCC4. Like other fission yeast NHEJ factors, Xrc4 is critically important for IR resistance of spores, in which no homologous recombination templates are available. Using both extrachromosomal and chromosomal DSB repair assays, we show that Xrc4 is essential for classical NHEJ. Exogenously expressed Xrc4 colocalizes with the LigIV homolog Lig4 at the chromatin region of the nucleus in a mutually dependent manner. Furthermore, like their human counterparts, Xrc4 and Lig4 interact with each other and this interaction requires the inter-BRCT linker and the second BRCT domain of Lig4. Our discovery of Xrc4 suggests that an XRCC4 family protein is universally required for classical NHEJ in eukaryotes.
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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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DNA-PK: a dynamic enzyme in a versatile DSB repair pathway. DNA Repair (Amst) 2014; 17:21-9. [PMID: 24680878 DOI: 10.1016/j.dnarep.2014.02.020] [Citation(s) in RCA: 260] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 02/17/2014] [Accepted: 02/24/2014] [Indexed: 11/23/2022]
Abstract
DNA double stranded breaks (DSBs) are the most cytoxic DNA lesion as the inability to properly repair them can lead to genomic instability and tumorigenesis. The prominent DSB repair pathway in humans is non-homologous end-joining (NHEJ). In the simplest sense, NHEJ mediates the direct re-ligation of the broken DNA molecule. However, NHEJ is a complex and versatile process that can repair DSBs with a variety of damages and ends via the utilization of a significant number of proteins. In this review we will describe the important factors and mechanisms modulating NHEJ with emphasis given to the versatility of this repair process and the DNA-PK complex.
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Smith S, Fox J, Mejia M, Ruangpradit W, Saberi A, Kim S, Choi Y, Oh S, Wang Y, Choi K, Li L, Hendrickson EA, Takeda S, Muller M, Myung K. Histone deacetylase inhibitors selectively target homology dependent DNA repair defective cells and elevate non-homologous endjoining activity. PLoS One 2014; 9:e87203. [PMID: 24466340 PMCID: PMC3900704 DOI: 10.1371/journal.pone.0087203] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 12/27/2013] [Indexed: 01/08/2023] Open
Abstract
Background We have previously used the ATAD5-luciferase high-throughput screening assay to identify genotoxic compounds with potential chemotherapeutic capabilities. The successful identification of known genotoxic agents, including the histone deacetylase inhibitor (HDACi) trichostatin A (TSA), confirmed the specificity of the screen since TSA has been widely studied for its ability to cause apoptosis in cancer cells. Because many cancers have acquired mutations in DNA damage checkpoints or repair pathways, we hypothesized that these cancers may be susceptible to treatments that target compensatory pathways. Here, we used a panel of isogenic chicken DT40 B lymphocyte mutant and human cell lines to investigate the ability of TSA to define selective pathways that promote HDACi toxicity. Results HDACi induced a DNA damage response and reduced viability in all repair deficient DT40 mutants although ATM-nulls were least affected. The most dramatic sensitivity was observed in mutants lacking the homology dependent repair (HDR) factor BLM or the non-homologous end-joining (NHEJ) and HDR factors, KU/RAD54, suggesting an involvement of either HDR or NHEJ in HDACi-induced cell death. To extend these findings, we measured the frequencies of HDR and NHEJ after HDACi treatment and monitored viability in human cell lines comparably deficient in HDR or NHEJ. Although no difference in HDR frequency was observed between HDACi treated and untreated cells, HDR-defective human cell lines were clearly more sensitive than wild type. Unexpectedly, cells treated with HDACis showed a significantly elevated NHEJ frequency. Conclusions HDACi targeting drugs induced significant increases in NHEJ activity in human cell lines but did not alter HDR frequency. Moreover, HDR is required for cellular resistance to HDACi therapy; therefore, NHEJ does not appear to be a critical axis for HDACi resistance. Rather, HDACi compounds induced DNA damage, most likely double strand breaks (DSBs), and HDR proficiency is correlated with cell survival.
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Affiliation(s)
- Stephanie Smith
- Genome Instability Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Jennifer Fox
- Genome Instability Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Marco Mejia
- Department of Molecular Biology and Microbiology, College of Medicine, University of Central Florida, Orlando, Florida, United States of America
| | - Wanvipa Ruangpradit
- Department of Molecular Biology and Microbiology, College of Medicine, University of Central Florida, Orlando, Florida, United States of America
| | - Alihossein Saberi
- Department of Radiation Genetics Kyoto University, Medical School, Kyoto, 606-8501 Japan
| | - Sunmi Kim
- Genome Instability Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- Department of Radiation Genetics Kyoto University, Medical School, Kyoto, 606-8501 Japan
- Department of Environmental Health School of Public Hearth, Seoul National University, Seoul, Korea
| | - Yongjun Choi
- Genome Instability Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Sehyun Oh
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
| | - Yucai Wang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston Texas, United States of America
| | - Kyungho Choi
- Department of Environmental Health School of Public Hearth, Seoul National University, Seoul, Korea
| | - Lei Li
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
- Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Eric A. Hendrickson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
| | - Shunichi Takeda
- Department of Radiation Genetics Kyoto University, Medical School, Kyoto, 606-8501 Japan
| | - Mark Muller
- Department of Molecular Biology and Microbiology, College of Medicine, University of Central Florida, Orlando, Florida, United States of America
| | - Kyungjae Myung
- Genome Instability Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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IMAMICHI S, SHARMA MK, KAMDAR RP, FUKUCHI M, MATSUMOTO Y. Ionizing radiation-induced XRCC4 phosphorylation is mediated through ATM in addition to DNA-PK. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2014; 90:365-72. [PMID: 25391321 PMCID: PMC4324928 DOI: 10.2183/pjab.90.365] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 10/07/2014] [Indexed: 05/28/2023]
Abstract
XRCC4 (X-ray cross-complementation group 4) is a protein associated with DNA ligase IV, which is thought to join two DNA ends at the final step of DNA double-strand break repair through non-homologous end-joining. It has been shown that, in response to irradiation or treatment with DNA damaging agents, XRCC4 undergoes phosphorylation, requiring DNA-PK. Here we explored possible role of ATM, which is structurally related to DNA-PK, in the regulation of XRCC4. The radiosensitizing effects of DNA-PK inhibitor and/or ATM inhibitor were dependent on XRCC4. DNA-PK inhibitor and ATM inhibitor did not affect the ionizing radiation-induced chromatin recruitment of XRCC4. Ionizing radiation-induced phosphorylation of XRCC4 in the chromatin-bound fraction was largely inhibited by DNA-PK inhibitor but further diminished by the combination with ATM inhibitor. The present results indicated that XRCC4 phosphorylation is mediated through ATM as well as DNA-PK, although DNA-PK plays the major role. We would propose a possible model that DNA-PK and ATM acts in parallel upstream of XRCC4, regulating through phosphorylation.
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Affiliation(s)
- Shoji IMAMICHI
- Research Laboratory for Nuclear Reactors and Department of Nuclear Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo, Japan
- Division of Chemotherapy and Clinical Research, National Cancer Center Research Institute, Tokyo, Japan
| | - Mukesh Kumar SHARMA
- Research Laboratory for Nuclear Reactors and Department of Nuclear Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo, Japan
- Department of Zoology, R.L.S. Govt. (P.G.) College, Kaladera (Jaipur), India
| | - Radhika Pankaj KAMDAR
- Research Laboratory for Nuclear Reactors and Department of Nuclear Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo, Japan
- Division of Clinical Immunology, Department of Laboratory Medicine, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Mikoto FUKUCHI
- Research Laboratory for Nuclear Reactors and Department of Nuclear Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo, Japan
| | - Yoshihisa MATSUMOTO
- Research Laboratory for Nuclear Reactors and Department of Nuclear Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo, Japan
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Chatterjee P, Plesca D, Mazumder S, Boutros J, Yannone SM, Almasan A. Defective chromatin recruitment and retention of NHEJ core components in human tumor cells expressing a Cyclin E fragment. Nucleic Acids Res 2013; 41:10157-69. [PMID: 24021630 PMCID: PMC3905870 DOI: 10.1093/nar/gkt812] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Exposure to genotoxic agents, such as ionizing radiation (IR), produces double-strand breaks, repaired predominantly in mammalian cells by non-homologous end-joining (NHEJ). Ku70 was identified as an interacting partner of a proteolytic Cyclin E (CycE) fragment, p18CycE. p18CycE endogenous generation during IR-induced apoptosis in leukemic cells and its stable expression in epithelial tumor cells sensitized to IR. γH2AX IR-induced foci (IRIFs) and comet assays indicated ineffective NHEJ DNA repair in p18CycE-expressing cells. DNA pull-down and chromatin recruitment assays revealed that retention of NHEJ factors to double-strand breaks, but not recruitment, was diminished. Similarly, IRIFs of phosphorylated T2609 and S2056-DNA-PKcs and its target S1778-53BP1 were greatly decreased in p18CycE-expressing cells. As a result, DNA-PKcs chromatin association was also increased. 53BP1 IRIFs were suppressed when p18CycE was generated in leukemic cells and in epithelial cells stably expressing p18CycE. Ataxia telangiectasia mutated was activated but not its 53BP1 and MDC1 targets. These data indicate a profound influence of p18CycE on NHEJ through its interference with DNA-PKcs conformation and/or dimerization, which is required for effective DNA repair, making the p18CycE-expressing cells more IR sensitive. These studies provide unique mechanistic insights into NHEJ misregulation in human tumor cells, in which defects in NHEJ core components are rare.
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Affiliation(s)
- Payel Chatterjee
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA, School of Biomedical Sciences, Kent State University, Kent, OH 44234, USA, Department of Chemistry, Cleveland State University, Cleveland, OH 44115, USA, Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA and Department of Radiation Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH 44195, USA
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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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Detection and repair of ionizing radiation-induced DNA double strand breaks: new developments in nonhomologous end joining. Int J Radiat Oncol Biol Phys 2013; 86:440-9. [PMID: 23433795 DOI: 10.1016/j.ijrobp.2013.01.011] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 01/07/2013] [Indexed: 01/13/2023]
Abstract
DNA damage can occur as a result of endogenous metabolic reactions and replication stress or from exogenous sources such as radiation therapy and chemotherapy. DNA double strand breaks are the most cytotoxic form of DNA damage, and defects in their repair can result in genome instability, a hallmark of cancer. The major pathway for the repair of ionizing radiation-induced DSBs in human cells is nonhomologous end joining. Here we review recent advances on the mechanism of nonhomologous end joining, as well as new findings on its component proteins and regulation.
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Mahaney BL, Hammel M, Meek K, Tainer JA, Lees-Miller SP. XRCC4 and XLF form long helical protein filaments suitable for DNA end protection and alignment to facilitate DNA double strand break repair. Biochem Cell Biol 2013; 91:31-41. [PMID: 23442139 DOI: 10.1139/bcb-2012-0058] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
DNA double strand breaks (DSBs), induced by ionizing radiation (IR) and endogenous stress including replication failure, are the most cytotoxic form of DNA damage. In human cells, most IR-induced DSBs are repaired by the nonhomologous end joining (NHEJ) pathway. One of the most critical steps in NHEJ is ligation of DNA ends by DNA ligase IV (LIG4), which interacts with, and is stabilized by, the scaffolding protein X-ray cross-complementing gene 4 (XRCC4). XRCC4 also interacts with XRCC4-like factor (XLF, also called Cernunnos); yet, XLF has been one of the least mechanistically understood proteins and precisely how XLF functions in NHEJ has been enigmatic. Here, we examine current combined structural and mutational findings that uncover integrated functions of XRCC4 and XLF and reveal their interactions to form long, helical protein filaments suitable to protect and align DSB ends. XLF-XRCC4 provides a global structural scaffold for ligating DSBs without requiring long DNA ends, thus ensuring accurate and efficient ligation and repair. The assembly of these XRCC4-XLF filaments, providing both DNA end protection and alignment, may commit cells to NHEJ with general biological implications for NHEJ and DSB repair processes and their links to cancer predispositions and interventions.
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Affiliation(s)
- Brandi L Mahaney
- Department of Biochemistry, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
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40
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Pathways for genome integrity in G2 phase of the cell cycle. Biomolecules 2012; 2:579-607. [PMID: 24970150 PMCID: PMC4030857 DOI: 10.3390/biom2040579] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 11/17/2012] [Accepted: 11/23/2012] [Indexed: 12/31/2022] Open
Abstract
The maintenance of genome integrity is important for normal cellular functions, organism development and the prevention of diseases, such as cancer. Cellular pathways respond immediately to DNA breaks leading to the initiation of a multi-facetted DNA damage response, which leads to DNA repair and cell cycle arrest. Cell cycle checkpoints provide the cell time to complete replication and repair the DNA damage before it can continue to the next cell cycle phase. The G2/M checkpoint plays an especially important role in ensuring the propagation of error-free copies of the genome to each daughter cell. Here, we review recent progress in our understanding of DNA repair and checkpoint pathways in late S and G2 phases. This review will first describe the current understanding of normal cell cycle progression through G2 phase to mitosis. It will also discuss the DNA damage response including cell cycle checkpoint control and DNA double-strand break repair. Finally, we discuss the emerging concept that DNA repair pathways play a major role in the G2/M checkpoint pathway thereby blocking cell division as long as DNA lesions are present.
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41
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Liu S, Opiyo SO, Manthey K, Glanzer JG, Ashley AK, Amerin C, Troksa K, Shrivastav M, Nickoloff JA, Oakley GG. Distinct roles for DNA-PK, ATM and ATR in RPA phosphorylation and checkpoint activation in response to replication stress. Nucleic Acids Res 2012; 40:10780-94. [PMID: 22977173 PMCID: PMC3510507 DOI: 10.1093/nar/gks849] [Citation(s) in RCA: 188] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
DNA damage encountered by DNA replication forks poses risks of genome destabilization, a
precursor to carcinogenesis. Damage checkpoint systems cause cell cycle arrest, promote
repair and induce programed cell death when damage is severe. Checkpoints are critical
parts of the DNA damage response network that act to suppress cancer. DNA damage and
perturbation of replication machinery causes replication stress, characterized by
accumulation of single-stranded DNA bound by replication protein A (RPA), which triggers
activation of ataxia telangiectasia and Rad3 related (ATR) and phosphorylation of the
RPA32, subunit of RPA, leading to Chk1 activation and arrest. DNA-dependent protein kinase
catalytic subunit (DNA-PKcs) [a kinase related to ataxia telangiectasia mutated (ATM) and
ATR] has well characterized roles in DNA double-strand break repair, but poorly understood
roles in replication stress-induced RPA phosphorylation. We show that DNA-PKcs mutant
cells fail to arrest replication following stress, and mutations in RPA32 phosphorylation
sites targeted by DNA-PKcs increase the proportion of cells in mitosis, impair ATR
signaling to Chk1 and confer a G2/M arrest defect. Inhibition of ATR and DNA-PK (but not
ATM), mimic the defects observed in cells expressing mutant RPA32. Cells expressing mutant
RPA32 or DNA-PKcs show sustained H2AX phosphorylation in response to replication stress
that persists in cells entering mitosis, indicating inappropriate mitotic entry with
unrepaired damage.
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Affiliation(s)
- Shengqin Liu
- Department of Oral Biology, University of Nebraska Medical Center, Omaha, NE 68583, USA
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Martín M, Terradas M, Tusell L, Genescà A. ATM and DNA-PKcs make a complementary couple in DNA double strand break repair. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2012; 751:29-35. [DOI: 10.1016/j.mrrev.2011.12.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 12/21/2011] [Accepted: 12/22/2011] [Indexed: 01/21/2023]
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Thompson LH. Recognition, signaling, and repair of DNA double-strand breaks produced by ionizing radiation in mammalian cells: the molecular choreography. Mutat Res 2012; 751:158-246. [PMID: 22743550 DOI: 10.1016/j.mrrev.2012.06.002] [Citation(s) in RCA: 261] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 06/09/2012] [Accepted: 06/16/2012] [Indexed: 12/15/2022]
Abstract
The faithful maintenance of chromosome continuity in human cells during DNA replication and repair is critical for preventing the conversion of normal diploid cells to an oncogenic state. The evolution of higher eukaryotic cells endowed them with a large genetic investment in the molecular machinery that ensures chromosome stability. In mammalian and other vertebrate cells, the elimination of double-strand breaks with minimal nucleotide sequence change involves the spatiotemporal orchestration of a seemingly endless number of proteins ranging in their action from the nucleotide level to nucleosome organization and chromosome architecture. DNA DSBs trigger a myriad of post-translational modifications that alter catalytic activities and the specificity of protein interactions: phosphorylation, acetylation, methylation, ubiquitylation, and SUMOylation, followed by the reversal of these changes as repair is completed. "Superfluous" protein recruitment to damage sites, functional redundancy, and alternative pathways ensure that DSB repair is extremely efficient, both quantitatively and qualitatively. This review strives to integrate the information about the molecular mechanisms of DSB repair that has emerged over the last two decades with a focus on DSBs produced by the prototype agent ionizing radiation (IR). The exponential growth of molecular studies, heavily driven by RNA knockdown technology, now reveals an outline of how many key protein players in genome stability and cancer biology perform their interwoven tasks, e.g. ATM, ATR, DNA-PK, Chk1, Chk2, PARP1/2/3, 53BP1, BRCA1, BRCA2, BLM, RAD51, and the MRE11-RAD50-NBS1 complex. Thus, the nature of the intricate coordination of repair processes with cell cycle progression is becoming apparent. This review also links molecular abnormalities to cellular pathology as much a possible and provides a framework of temporal relationships.
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Affiliation(s)
- Larry H Thompson
- Biology & Biotechnology Division, L452, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551-0808, United States.
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Jensik PJ, Huggenvik JI, Collard MW. Deformed epidermal autoregulatory factor-1 (DEAF1) interacts with the Ku70 subunit of the DNA-dependent protein kinase complex. PLoS One 2012; 7:e33404. [PMID: 22442688 PMCID: PMC3307728 DOI: 10.1371/journal.pone.0033404] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 02/14/2012] [Indexed: 11/19/2022] Open
Abstract
Deformed Epidermal Autoregulatory Factor 1 (DEAF1) is a transcription factor linked to suicide, cancer, autoimmune disorders and neural tube defects. To better understand the role of DEAF1 in protein interaction networks, a GST-DEAF1 fusion protein was used to isolate interacting proteins in mammalian cell lysates, and the XRCC6 (Ku70) and the XRCC5 (Ku80) subunits of DNA dependent protein kinase (DNA-PK) complex were identified by mass spectrometry, and the DNA-PK catalytic subunit was identified by immunoblotting. Interaction of DEAF1 with Ku70 and Ku80 was confirmed to occur within cells by co-immunoprecipitation of epitope-tagged proteins, and was mediated through interaction with the Ku70 subunit. Using in vitro GST-pulldowns, interaction between DEAF1 and the Ku70 subunit was mapped to the DEAF1 DNA binding domain and the C-terminal Bax-binding region of Ku70. In transfected cells, DEAF1 and Ku70 colocalized to the nucleus, but Ku70 could not relocalize a mutant cytoplasmic form of DEAF1 to the nucleus. Using an in vitro kinase assay, DEAF1 was phosphorylated by DNA-PK in a DNA-independent manner. Electrophoretic mobility shift assays showed that DEAF1 or Ku70/Ku80 did not interfere with the DNA binding of each other, but DNA containing DEAF1 binding sites inhibited the DEAF1-Ku70 interaction. The data demonstrates that DEAF1 can interact with the DNA-PK complex through interactions of its DNA binding domain with the carboxy-terminal region of Ku70 that contains the Bax binding domain, and that DEAF1 is a potential substrate for DNA-PK.
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Affiliation(s)
| | | | - Michael W. Collard
- Department of Physiology, Southern Illinois University School of Medicine, Carbondale, Illinois, United States of America
- * E-mail:
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Non-homologous end-joining partners in a helical dance: structural studies of XLF-XRCC4 interactions. Biochem Soc Trans 2012; 39:1387-92, suppl 2 p following 1392. [PMID: 21936820 DOI: 10.1042/bst0391387] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
XRCC4 (X-ray cross-complementation group 4) and XLF (XRCC4-like factor) are two essential interacting proteins in the human NHEJ (non-homologous end-joining) pathway that repairs DNA DSBs (double-strand breaks). The individual crystal structures show that the dimeric proteins are homologues with protomers containing head domains and helical coiled-coil tails related by approximate two-fold symmetry. Biochemical, mutagenesis, biophysical and structural studies have identified the regions of interaction between the two proteins and suggested models for the XLF-XRCC4 complex. An 8.5 Å (1 Å = 0.1 nm) resolution crystal structure of XLF-XRCC4 solved by molecular replacement, together with gel filtration and nano-ESI (nano-electrospray ionization)-MS results, demonstrates that XLF and XRCC4 dimers interact through their head domains and form an alternating left-handed helical structure with polypeptide coiled coils and pseudo-dyads of individual XLF and XRCC4 dimers at right angles to the helical axis.
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46
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Roy S, Andres SN, Vergnes A, Neal JA, Xu Y, Yu Y, Lees-Miller SP, Junop M, Modesti M, Meek K. XRCC4's interaction with XLF is required for coding (but not signal) end joining. Nucleic Acids Res 2012; 40:1684-94. [PMID: 22228831 PMCID: PMC3287172 DOI: 10.1093/nar/gkr1315] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
XRCC4 and XLF are structurally related proteins important for DNA Ligase IV function. XRCC4 forms a tight complex with DNA Ligase IV while XLF interacts directly with XRCC4. Both XRCC4 and XLF form homodimers that can polymerize as heterotypic filaments independently of DNA Ligase IV. Emerging structural and in vitro biochemical data suggest that XRCC4 and XLF together generate a filamentous structure that promotes bridging between DNA molecules. Here, we show that ablating XRCC4's affinity for XLF results in DNA repair deficits including a surprising deficit in VDJ coding, but not signal end joining. These data are consistent with a model whereby XRCC4/XLF complexes hold DNA ends together—stringently required for coding end joining, but dispensable for signal end joining. Finally, DNA-PK phosphorylation of XRCC4/XLF complexes disrupt DNA bridging in vitro, suggesting a regulatory role for DNA-PK's phosphorylation of XRCC4/XLF complexes.
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Affiliation(s)
- Sunetra Roy
- College of Veterinary Medicine and Departments of Microbiology & Molecular Genetics, Michigan State University, East Lansing, Michigan 48824, USA
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Meek K, Lees-Miller SP, Modesti M. N-terminal constraint activates the catalytic subunit of the DNA-dependent protein kinase in the absence of DNA or Ku. Nucleic Acids Res 2011; 40:2964-73. [PMID: 22167471 PMCID: PMC3326324 DOI: 10.1093/nar/gkr1211] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The DNA-dependent protein kinase (DNA-PK) was identified as an activity and as its three component polypeptides 25 and 15 years ago, respectively. It has been exhaustively characterized as being absolutely dependent on free double stranded DNA ends (to which it is directed by its regulatory subunit, Ku) for its activation as a robust nuclear serine/threonine protein kinase. Here, we report the unexpected finding of robust DNA-PKcs activation by N-terminal constraint, independent of either DNA or its regulatory subunit Ku. These data suggest that an N-terminal conformational change (likely induced by DNA binding) induces enzymatic activation.
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Affiliation(s)
- Katheryn Meek
- Department of Microbiology and Molecular Genetics, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA.
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48
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Hanakahi L. Effect of the Inositol Polyphosphate InsP6 on DNA-PK–Dependent Phosphorylation. Mol Cancer Res 2011; 9:1366-76. [DOI: 10.1158/1541-7786.mcr-11-0230] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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49
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Gapud EJ, Lee BS, Mahowald GK, Bassing CH, Sleckman BP. Repair of chromosomal RAG-mediated DNA breaks by mutant RAG proteins lacking phosphatidylinositol 3-like kinase consensus phosphorylation sites. THE JOURNAL OF IMMUNOLOGY 2011; 187:1826-34. [PMID: 21742970 DOI: 10.4049/jimmunol.1101388] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Ataxia telangiectasia mutated (ATM) and DNA-dependent protein kinase catalytic subunits (DNA-PKcs) are members of the phosphatidylinositol 3-like family of serine/threonine kinases that phosphorylate serines or threonines when positioned adjacent to a glutamine residue (SQ/TQ). Both kinases are activated rapidly by DNA double-strand breaks (DSBs) and regulate the function of proteins involved in DNA damage responses. In developing lymphocytes, DSBs are generated during V(D)J recombination, which is required to assemble the second exon of all Ag receptor genes. This reaction is initiated through a DNA cleavage step by the RAG1 and RAG2 proteins, which together comprise an endonuclease that generates DSBs at the border of two recombining gene segments and their flanking recombination signals. This DNA cleavage step is followed by a joining step, during which pairs of DNA coding and signal ends are ligated to form a coding joint and a signal joint, respectively. ATM and DNA-PKcs are integrally involved in the repair of both signal and coding ends, but the targets of these kinases involved in the repair process have not been fully elucidated. In this regard, the RAG1 and RAG2 proteins, which each have several SQ/TQ motifs, have been implicated in the repair of RAG-mediated DSBs. In this study, we use a previously developed approach for studying chromosomal V(D)J recombination that has been modified to allow for the analysis of RAG1 and RAG2 function. We show that phosphorylation of RAG1 or RAG2 by ATM or DNA-PKcs at SQ/TQ consensus sites is dispensable for the joining step of V(D)J recombination.
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Affiliation(s)
- Eric J Gapud
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
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50
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Gapud EJ, Sleckman BP. Unique and redundant functions of ATM and DNA-PKcs during V(D)J recombination. Cell Cycle 2011; 10:1928-35. [PMID: 21673501 DOI: 10.4161/cc.10.12.16011] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Lymphocyte antigen receptor genes are assembled through the process of V(D)J recombination, during which pairwise DNA cleavage of gene segments results in the formation of four DNA ends that are resolved into a coding joint and a signal joint. The joining of these DNA ends occurs in G1-phase lymphocytes and is mediated by the non-homologous end-joining (NHEJ) pathway of DNA double-strand break (DSB) repair. The ataxia telangiectasia mutated (ATM) and the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), two related kinases, both function in the repair of DNA breaks generated during antigen receptor gene assembly. Although these proteins have unique functions during coding joint formation, their activities in signal joint formation, if any, have been less clear. However, two recent studies demonstrated that ATM and DNA-PKcs have overlapping activities important for signal joint formation. Here, we discuss the unique and shared activities of the ATM and DNA-PKcs kinases during V(D)J recombination, a process that is essential for lymphocyte development and the diversification of antigen receptors.
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Affiliation(s)
- Eric J Gapud
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA
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