1
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Lorković ZJ, Klingenbrunner M, Cho CH, Berger F. Identification of plants' functional counterpart of the metazoan mediator of DNA Damage checkpoint 1. EMBO Rep 2024; 25:1936-1961. [PMID: 38438802 PMCID: PMC11014961 DOI: 10.1038/s44319-024-00107-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 02/13/2024] [Accepted: 02/19/2024] [Indexed: 03/06/2024] Open
Abstract
Induction of DNA damage triggers rapid phosphorylation of the histone H2A.X (γH2A.X). In animals, mediator of DNA damage checkpoint 1 (MDC1) binds γH2A.X through a tandem BRCA1 carboxyl-terminal (tBRCT) domain and mediates recruitment of downstream effectors of DNA damage response (DDR). However, readers of this modification in plants have remained elusive. We show that from the Arabidopsis BRCT domain proteome, BCP1-4 proteins with tBRCT domains are involved in DDR. Through its tBRCT domain BCP4 binds γH2A.X in vitro and localizes to DNA damage-induced foci in an H2A.X-dependent manner. BCP4 also contains a domain that interacts directly with NBS1 and thus acts as a functional counterpart of MDC1. We also show that BCP1, that contains two tBRCT domains, co-localizes with γH2A.X but it does not bind γH2A.X suggesting functional similarity with human PAXIP1. A phylogenetic analysis supports that PAXIP1 and MDC1 in metazoa and their plant counterparts evolved independently from common ancestors with tBRCT domains. Collectively, our study reveals missing components and provides mechanistic and evolutionary insights into plant DDR.
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Affiliation(s)
- Zdravko J Lorković
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Vienna, Austria.
| | - Michael Klingenbrunner
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Vienna, Austria
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Chung Hyun Cho
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Vienna, Austria
| | - Frédéric Berger
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Vienna, Austria.
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2
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Collin V, Biquand É, Tremblay V, Lavoie ÉG, Blondeau A, Gravel A, Galloy M, Lashgari A, Dessapt J, Côté J, Flamand L, Fradet-Turcotte A. The immediate-early protein 1 of human herpesvirus 6B interacts with NBS1 and inhibits ATM signaling. EMBO Rep 2024; 25:725-744. [PMID: 38177923 PMCID: PMC10897193 DOI: 10.1038/s44319-023-00035-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 12/03/2023] [Accepted: 12/06/2023] [Indexed: 01/06/2024] Open
Abstract
Viral infection often trigger an ATM serine/threonine kinase (ATM)-dependent DNA damage response in host cells that suppresses viral replication. Viruses evolved different strategies to counteract this antiviral surveillance system. Here, we report that human herpesvirus 6B (HHV-6B) infection causes genomic instability by suppressing ATM signaling in host cells. Expression of immediate-early protein 1 (IE1) phenocopies this phenotype and blocks homology-directed double-strand break repair. Mechanistically, IE1 interacts with NBS1, and inhibits ATM signaling through two distinct domains. HHV-6B seems to efficiently inhibit ATM signaling as further depletion of either NBS1 or ATM do not significantly boost viral replication in infected cells. Interestingly, viral integration of HHV-6B into the host's telomeres is not strictly dependent on NBS1, challenging current models where integration occurs through homology-directed repair. Given that spontaneous IE1 expression has been detected in cells of subjects with inherited chromosomally-integrated form of HHV-6B (iciHHV-6B), a condition associated with several health conditions, our results raise the possibility of a link between genomic instability and the development of iciHHV-6-associated diseases.
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Affiliation(s)
- Vanessa Collin
- Division of Infectious Disease and Immunity, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1V 4G2, Canada
- Department of Microbiology, Infectious Disease and Immunology, Faculty of Medicine, Université Laval, Quebec City, QC, G1V 0A6, Canada
| | - Élise Biquand
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Department of Molecular biology, Medical Biochemistry and Pathology, Faculty of Medicine, Université Laval, Québec City, QC, G1V 0A6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
- INSERM, Centre d'Étude des Pathologies Respiratoires (CEPR), UMR 1100, Université de Tours, Tours, France
| | - Vincent Tremblay
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Department of Molecular biology, Medical Biochemistry and Pathology, Faculty of Medicine, Université Laval, Québec City, QC, G1V 0A6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
| | - Élise G Lavoie
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
| | - Andréanne Blondeau
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
| | - Annie Gravel
- Division of Infectious Disease and Immunity, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1V 4G2, Canada
- Department of Microbiology, Infectious Disease and Immunology, Faculty of Medicine, Université Laval, Quebec City, QC, G1V 0A6, Canada
| | - Maxime Galloy
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Department of Molecular biology, Medical Biochemistry and Pathology, Faculty of Medicine, Université Laval, Québec City, QC, G1V 0A6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
| | - Anahita Lashgari
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Department of Molecular biology, Medical Biochemistry and Pathology, Faculty of Medicine, Université Laval, Québec City, QC, G1V 0A6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
| | - Julien Dessapt
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Department of Molecular biology, Medical Biochemistry and Pathology, Faculty of Medicine, Université Laval, Québec City, QC, G1V 0A6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
| | - Jacques Côté
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Department of Molecular biology, Medical Biochemistry and Pathology, Faculty of Medicine, Université Laval, Québec City, QC, G1V 0A6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
| | - Louis Flamand
- Division of Infectious Disease and Immunity, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1V 4G2, Canada.
- Department of Microbiology, Infectious Disease and Immunology, Faculty of Medicine, Université Laval, Quebec City, QC, G1V 0A6, Canada.
| | - Amélie Fradet-Turcotte
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada.
- Department of Molecular biology, Medical Biochemistry and Pathology, Faculty of Medicine, Université Laval, Québec City, QC, G1V 0A6, Canada.
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada.
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3
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El‐Kamand S, Adams MN, Matthews JM, Du Plessis M, Crossett B, Connolly A, Breen N, Dudley A, Richard DJ, Gamsjaeger R, Cubeddu L. The molecular details of a novel phosphorylation-dependent interaction between MRN and the SOSS complex. Protein Sci 2023; 32:e4782. [PMID: 37705456 PMCID: PMC10521234 DOI: 10.1002/pro.4782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 08/08/2023] [Accepted: 09/11/2023] [Indexed: 09/15/2023]
Abstract
The repair of double-strand DNA breaks (DSBs) by homologous recombination is crucial in the maintenance of genome integrity. While the key role of the Mre11-Rad50-Nbs1 (MRN) complex in repair is well known, hSSB1 (SOSSB and OBFC2B), one of the main components of the sensor of single-stranded DNA (SOSS) protein complex, has also been shown to rapidly localize to DSB breaks and promote repair. We have previously demonstrated that hSSB1 binds directly to Nbs1, a component of the MRN complex, in a DNA damage-independent manner. However, recruitment of the MRN complex has also been demonstrated by an interaction between Integrator Complex Subunit 3 (INTS3; also known as SOSSA), another member of the SOSS complex, and Nbs1. In this study, we utilize a combined approach of in silico, biochemical, and functional experiments to uncover the molecular details of INTS3 binding to Nbs1. We demonstrate that the forkhead-associated domain of Nbs1 interacts with INTS3 via phosphorylation-dependent binding to INTS3 at Threonine 592, with contributions from Serine 590. Based on these data, we propose a model of MRN recruitment to a DSB via INTS3.
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Affiliation(s)
- Serene El‐Kamand
- School of ScienceWestern Sydney UniversityPenrithNew South WalesAustralia
| | - Mark N. Adams
- Centre for Genomics and Personalised Health, School of Biomedical Sciences, Faculty of HealthTranslational Research Institute, Queensland University of TechnologyBrisbaneQueenslandAustralia
| | - Jacqueline M. Matthews
- School of Life and Environmental SciencesUniversity of SydneySydneyNew South WalesAustralia
| | | | - Ben Crossett
- Sydney Mass SpectrometryUniversity of SydneySydneyNew South WalesAustralia
| | - Angela Connolly
- Sydney Mass SpectrometryUniversity of SydneySydneyNew South WalesAustralia
| | - Natasha Breen
- School of ScienceWestern Sydney UniversityPenrithNew South WalesAustralia
| | - Alexander Dudley
- School of ScienceWestern Sydney UniversityPenrithNew South WalesAustralia
| | - Derek J. Richard
- Centre for Genomics and Personalised Health, School of Biomedical Sciences, Faculty of HealthTranslational Research Institute, Queensland University of TechnologyBrisbaneQueenslandAustralia
| | - Roland Gamsjaeger
- School of ScienceWestern Sydney UniversityPenrithNew South WalesAustralia
- School of Life and Environmental SciencesUniversity of SydneySydneyNew South WalesAustralia
| | - Liza Cubeddu
- School of ScienceWestern Sydney UniversityPenrithNew South WalesAustralia
- School of Life and Environmental SciencesUniversity of SydneySydneyNew South WalesAustralia
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4
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Species variations in XRCC1 recruitment strategies for FHA domain-containing proteins. DNA Repair (Amst) 2022; 110:103263. [PMID: 35026705 PMCID: PMC9282668 DOI: 10.1016/j.dnarep.2021.103263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 11/07/2021] [Accepted: 12/21/2021] [Indexed: 02/03/2023]
Abstract
DNA repair scaffolds XRCC1 and XRCC4 utilize a phosphopeptide FHA domain binding motif (FBM) of the form Y-x-x-pS-pT-D-E that supports recruitment of three identified FHA domain-containing DNA repair proteins: polynucleotide kinase/phosphatase (PNKP), aprataxin (APTX), and a third protein, APLF, that functions as a scaffold in support of non-homologous end joining (NHEJ). Mammalian dimeric XRCC4 is able to interact with two of these proteins at any given time, while monomeric XRCC1 binds only one. However, sequence analysis indicates that amphibian and teleost XRCC1 generally contain two FHA binding motifs. X1-FBM1, is similar to the single mammalian XRCC1 FBM and probably functions similarly. X1-FBM2, is more similar to mammalian XRCC4 FBM; it is located closer to the XRCC1 BRCT1 domain and probably is less discriminating among its three likely binding partners. Availability of an additional PNKP or APTX recruitment motif may alleviate the bottleneck that results from using a single FBM motif for recruitment of multiple repair factors. Alternatively, recruitment of APLF by X1-FBM2 may function to rescue a misdirected or unsuccessful SSB repair response by redirecting the damaged DNA to the NHEJ pathway, - a need that results from the ambiguity of the PARP1 signal regarding the nature of the damage. Evaluation of XRCC4 FBMs in acanthomorphs, which account for a majority of the reported teleost sequences, reveals the presence of an additional XRCC4-like paralog, distinct from other previously described members of the XRCC4 superfamily. The FBM is typically absent in acanthomorph XRCC4, but present in the XRCC4-like paralog. Modeling suggests that XRCC4 and its paralog may form homodimers or XRCC4-XRCC4-like heterodimers.
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5
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Kim K, Kirby TW, Perera L, London RE. Phosphopeptide interactions of the Nbs1 N-terminal FHA-BRCT1/2 domains. Sci Rep 2021; 11:9046. [PMID: 33907233 PMCID: PMC8079451 DOI: 10.1038/s41598-021-88400-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 04/05/2021] [Indexed: 11/21/2022] Open
Abstract
Human Nbs1, a component of the MRN complex involved in DNA double strand break repair, contains a concatenated N-terminal FHA-BRCT1/2 sequence that supports interaction with multiple phosphopeptide binding partners. MDC1 binding localizes Nbs1 to the damage site, while binding of CDK-phosphorylated CtIP activates additional ATM-dependent CtIP phosphorylation, modulating substrate-dependent resection. We have investigated the phosphopeptide binding characteristics of Nbs1 BRCT1/2 based on a molecular modeling approach that revealed structural homology with the tandem TopBP1 BRCT7/8 domains. Relevance of the model was substantiated by the ability of TopBP1-binding FANCJ phosphopeptide to interact with hsNbsBRCT1/2, albeit with lower affinity. The modeled BRCT1/2 is characterized by low pSer/pThr selectivity, preference for a cationic residue at the + 2 position, and an inter-domain binding cleft selective for hydrophobic residues at the + 3/ + 4 positions. These features provide insight into the basis for interaction of SDT motifs with the BRCT1/2 domains and allowed identification of CtIP pSer347- and pThr847-containing phosphopeptides as high and lower affinity ligands, respectively. Among other binding partners considered, rodent XRCC1 contains an SDT sequence in the second linker consistent with high-affinity Nbs1 binding, while human XRCC1 lacks this motif, but contains other phosphorylated sequences that exhibit low-affinity binding.
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Affiliation(s)
- Kyungmin Kim
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC, 27709, USA
| | - Thomas W Kirby
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC, 27709, USA
| | - Lalith Perera
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC, 27709, USA
| | - Robert E London
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC, 27709, USA.
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6
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Tumor Evolution and Therapeutic Choice Seen through a Prism of Circulating Tumor Cell Genomic Instability. Cells 2021; 10:cells10020337. [PMID: 33562741 PMCID: PMC7915006 DOI: 10.3390/cells10020337] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 01/29/2021] [Accepted: 02/02/2021] [Indexed: 12/13/2022] Open
Abstract
Circulating tumor cells (CTCs) provide an accessible tool for investigating tumor heterogeneity and cell populations with metastatic potential. Although an in-depth molecular investigation is limited by the extremely low CTC count in circulation, significant progress has been made recently in single-cell analytical processes. Indeed, CTC monitoring through molecular and functional characterization may provide an understanding of genomic instability (GI) molecular mechanisms, which contribute to tumor evolution and emergence of resistant clones. In this review, we discuss the sources and consequences of GI seen through single-cell analysis of CTCs in different types of tumors. We present a detailed overview of chromosomal instability (CIN) in CTCs assessed by fluorescence in situ hybridization (FISH), and we reveal utility of CTC single-cell sequencing in identifying copy number alterations (CNA) oncogenic drivers. We highlight the role of CIN in CTC-driven metastatic progression and acquired resistance, and we comment on the technical obstacles and challenges encountered during single CTC analysis. We focus on the DNA damage response and depict DNA-repair-related dynamic biomarkers reported to date in CTCs and their role in predicting response to genotoxic treatment. In summary, the suggested relationship between genomic aberrations in CTCs and prognosis strongly supports the potential utility of GI monitoring in CTCs in clinical risk assessment and therapeutic choice.
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7
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Zell J, Rota Sperti F, Britton S, Monchaud D. DNA folds threaten genetic stability and can be leveraged for chemotherapy. RSC Chem Biol 2021; 2:47-76. [PMID: 35340894 PMCID: PMC8885165 DOI: 10.1039/d0cb00151a] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 09/20/2020] [Indexed: 12/22/2022] Open
Abstract
Damaging DNA is a current and efficient strategy to fight against cancer cell proliferation. Numerous mechanisms exist to counteract DNA damage, collectively referred to as the DNA damage response (DDR) and which are commonly dysregulated in cancer cells. Precise knowledge of these mechanisms is necessary to optimise chemotherapeutic DNA targeting. New research on DDR has uncovered a series of promising therapeutic targets, proteins and nucleic acids, with application notably via an approach referred to as combination therapy or combinatorial synthetic lethality. In this review, we summarise the cornerstone discoveries which gave way to the DNA being considered as an anticancer target, and the manipulation of DDR pathways as a valuable anticancer strategy. We describe in detail the DDR signalling and repair pathways activated in response to DNA damage. We then summarise the current understanding of non-B DNA folds, such as G-quadruplexes and DNA junctions, when they are formed and why they can offer a more specific therapeutic target compared to that of canonical B-DNA. Finally, we merge these subjects to depict the new and highly promising chemotherapeutic strategy which combines enhanced-specificity DNA damaging and DDR targeting agents. This review thus highlights how chemical biology has given rise to significant scientific advances thanks to resolutely multidisciplinary research efforts combining molecular and cell biology, chemistry and biophysics. We aim to provide the non-specialist reader a gateway into this exciting field and the specialist reader with a new perspective on the latest results achieved and strategies devised.
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Affiliation(s)
- Joanna Zell
- Institut de Chimie Moléculaire de l'Université de Bourgogne, ICMUB CNRS UMR 6302, UBFC Dijon France
| | - Francesco Rota Sperti
- Institut de Chimie Moléculaire de l'Université de Bourgogne, ICMUB CNRS UMR 6302, UBFC Dijon France
| | - Sébastien Britton
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS Toulouse France
- Équipe Labellisée la Ligue Contre le Cancer 2018 Toulouse France
| | - David Monchaud
- Institut de Chimie Moléculaire de l'Université de Bourgogne, ICMUB CNRS UMR 6302, UBFC Dijon France
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8
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Mutation of Conserved Mre11 Residues Alter Protein Dynamics to Separate Nuclease Functions. J Mol Biol 2020; 432:3289-3308. [PMID: 32246962 DOI: 10.1016/j.jmb.2020.03.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 03/25/2020] [Accepted: 03/26/2020] [Indexed: 02/08/2023]
Abstract
Naked and protein-blocked DNA ends occur naturally during immune cell development, meiosis, and at telomeres as well as from aborted topoisomerase reactions, collapsed replication forks, and other stressors. Damaged DNA ends are dangerous in cells and if left unrepaired can lead to genomic rearrangement, loss of genetic information, and eventually cancer. Mre11 is part of the Mre11-Rad50-Nbs1 complex that recognizes DNA double-strand breaks and has exonuclease and endonuclease activities that help to initiate the repair processes to resolve these broken DNA ends. In fact, these activities are crucial for proper DNA damage repair pathway choice. Here, using Pyrococcus furiosus Mre11, we question how two Mre11 separation-of-function mutants, one previously described but the second first described here, maintain endonuclease activity in the absence of exonuclease activity. To start, we performed solution-state NMR experiments to assign the side-chain methyl groups of the 64-kDa Mre11 nuclease and capping domains, which allowed us to describe the structural differences between Mre11 bound to exo- and endonuclease substrates. Then, through biochemical and biophysical characterization, including NMR structural and dynamics studies, we compared the two mutants and determined that both affect the dynamic features and double-stranded DNA binding properties of Mre11, but in different ways. In total, our results illuminate the structural and dynamic landscape of Mre11 nuclease function.
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9
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Mooser C, Symeonidou IE, Leimbacher PA, Ribeiro A, Shorrocks AMK, Jungmichel S, Larsen SC, Knechtle K, Jasrotia A, Zurbriggen D, Jeanrenaud A, Leikauf C, Fink D, Nielsen ML, Blackford AN, Stucki M. Treacle controls the nucleolar response to rDNA breaks via TOPBP1 recruitment and ATR activation. Nat Commun 2020; 11:123. [PMID: 31913317 PMCID: PMC6949271 DOI: 10.1038/s41467-019-13981-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 12/10/2019] [Indexed: 01/10/2023] Open
Abstract
Induction of DNA double-strand breaks (DSBs) in ribosomal DNA (rDNA) repeats is associated with ATM-dependent repression of ribosomal RNA synthesis and large-scale reorganization of nucleolar architecture, but the signaling events that regulate these responses are largely elusive. Here we show that the nucleolar response to rDNA breaks is dependent on both ATM and ATR activity. We further demonstrate that ATM- and NBS1-dependent recruitment of TOPBP1 in the nucleoli is required for inhibition of ribosomal RNA synthesis and nucleolar segregation in response to rDNA breaks. Mechanistically, TOPBP1 recruitment is mediated by phosphorylation-dependent interactions between three of its BRCT domains and conserved phosphorylated Ser/Thr residues at the C-terminus of the nucleolar phosphoprotein Treacle. Our data thus reveal an important cooperation between TOPBP1 and Treacle in the signaling cascade that triggers transcriptional inhibition and nucleolar segregation in response to rDNA breaks.
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Affiliation(s)
- Clémence Mooser
- Department of Gynecology, University of Zurich, Wagistrasse 14, CH-8952, Schlieren, Switzerland
| | - Ioanna-Eleni Symeonidou
- Department of Gynecology, University of Zurich, Wagistrasse 14, CH-8952, Schlieren, Switzerland
| | - Pia-Amata Leimbacher
- Department of Gynecology, University of Zurich, Wagistrasse 14, CH-8952, Schlieren, Switzerland
| | - Alison Ribeiro
- Department of Gynecology, University of Zurich, Wagistrasse 14, CH-8952, Schlieren, Switzerland
| | - Ann-Marie K Shorrocks
- Department of Oncology, Medical Research Council Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS, UK
- Cancer Research UK/Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, Oxford, OX3 7DQ, UK
| | - Stephanie Jungmichel
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Faculty of Health and Medical Sciences, Bledgamsvej 3B DK-2200, Copenhagen, Denmark
| | - Sara C Larsen
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Faculty of Health and Medical Sciences, Bledgamsvej 3B DK-2200, Copenhagen, Denmark
| | - Katja Knechtle
- Department of Gynecology, University of Zurich, Wagistrasse 14, CH-8952, Schlieren, Switzerland
| | - Arti Jasrotia
- Department of Gynecology, University of Zurich, Wagistrasse 14, CH-8952, Schlieren, Switzerland
| | - Diana Zurbriggen
- Department of Gynecology, University of Zurich, Wagistrasse 14, CH-8952, Schlieren, Switzerland
| | - Alain Jeanrenaud
- Department of Gynecology, University of Zurich, Wagistrasse 14, CH-8952, Schlieren, Switzerland
| | - Colin Leikauf
- Department of Gynecology, University of Zurich, Wagistrasse 14, CH-8952, Schlieren, Switzerland
| | - Daniel Fink
- Department of Gynecology, University of Zurich, Wagistrasse 14, CH-8952, Schlieren, Switzerland
| | - Michael L Nielsen
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Faculty of Health and Medical Sciences, Bledgamsvej 3B DK-2200, Copenhagen, Denmark
| | - Andrew N Blackford
- Department of Oncology, Medical Research Council Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS, UK
- Cancer Research UK/Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, Oxford, OX3 7DQ, UK
| | - Manuel Stucki
- Department of Gynecology, University of Zurich, Wagistrasse 14, CH-8952, Schlieren, Switzerland.
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10
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Leimbacher PA, Jones SE, Shorrocks AMK, de Marco Zompit M, Day M, Blaauwendraad J, Bundschuh D, Bonham S, Fischer R, Fink D, Kessler BM, Oliver AW, Pearl LH, Blackford AN, Stucki M. MDC1 Interacts with TOPBP1 to Maintain Chromosomal Stability during Mitosis. Mol Cell 2019; 74:571-583.e8. [PMID: 30898438 PMCID: PMC6509287 DOI: 10.1016/j.molcel.2019.02.014] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 12/30/2018] [Accepted: 02/11/2019] [Indexed: 12/29/2022]
Abstract
In mitosis, cells inactivate DNA double-strand break (DSB) repair pathways to preserve genome stability. However, some early signaling events still occur, such as recruitment of the scaffold protein MDC1 to phosphorylated histone H2AX at DSBs. Yet, it remains unclear whether these events are important for maintaining genome stability during mitosis. Here, we identify a highly conserved protein-interaction surface in MDC1 that is phosphorylated by CK2 and recognized by the DNA-damage response mediator protein TOPBP1. Disruption of MDC1-TOPBP1 binding causes a specific loss of TOPBP1 recruitment to DSBs in mitotic but not interphase cells, accompanied by mitotic radiosensitivity, increased micronuclei, and chromosomal instability. Mechanistically, we find that TOPBP1 forms filamentous structures capable of bridging MDC1 foci in mitosis, indicating that MDC1-TOPBP1 complexes tether DSBs until repair is reactivated in the following G1 phase. Thus, we reveal an important, hitherto-unnoticed cooperation between MDC1 and TOPBP1 in maintaining genome stability during cell division.
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Affiliation(s)
- Pia-Amata Leimbacher
- Department of Gynecology, University Hospital and University of Zurich, Wagistrasse 14, 8952 Schlieren, Switzerland
| | - Samuel E Jones
- Department of Oncology, Medical Research Council Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK; Cancer Research UK/Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, Oxford OX3 7DQ, UK
| | - Ann-Marie K Shorrocks
- Department of Oncology, Medical Research Council Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK; Cancer Research UK/Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, Oxford OX3 7DQ, UK
| | - Mara de Marco Zompit
- Department of Gynecology, University Hospital and University of Zurich, Wagistrasse 14, 8952 Schlieren, Switzerland
| | - Matthew Day
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, UK
| | - Jordy Blaauwendraad
- Department of Gynecology, University Hospital and University of Zurich, Wagistrasse 14, 8952 Schlieren, Switzerland
| | - Diana Bundschuh
- Department of Gynecology, University Hospital and University of Zurich, Wagistrasse 14, 8952 Schlieren, Switzerland
| | - Sarah Bonham
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7FZ, UK
| | - Roman Fischer
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7FZ, UK
| | - Daniel Fink
- Department of Gynecology, University Hospital and University of Zurich, Wagistrasse 14, 8952 Schlieren, Switzerland
| | - Benedikt M Kessler
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7FZ, UK
| | - Antony W Oliver
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, UK
| | - Laurence H Pearl
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, UK
| | - Andrew N Blackford
- Department of Oncology, Medical Research Council Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK; Cancer Research UK/Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, Oxford OX3 7DQ, UK.
| | - Manuel Stucki
- Department of Gynecology, University Hospital and University of Zurich, Wagistrasse 14, 8952 Schlieren, Switzerland.
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11
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Anand R, Jasrotia A, Bundschuh D, Howard SM, Ranjha L, Stucki M, Cejka P. NBS1 promotes the endonuclease activity of the MRE11-RAD50 complex by sensing CtIP phosphorylation. EMBO J 2019; 38:e101005. [PMID: 30787182 PMCID: PMC6443204 DOI: 10.15252/embj.2018101005] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 01/08/2019] [Accepted: 02/01/2019] [Indexed: 11/09/2022] Open
Abstract
DNA end resection initiates DNA double-strand break repair by homologous recombination. MRE11-RAD50-NBS1 and phosphorylated CtIP perform the first resection step via MRE11-catalyzed endonucleolytic DNA cleavage. Human NBS1, more than its homologue Xrs2 in Saccharomyces cerevisiae, is crucial for this process, highlighting complex mechanisms that regulate the MRE11 nuclease in higher eukaryotes. Using a reconstituted system, we show here that NBS1, through its FHA and BRCT domains, functions as a sensor of CtIP phosphorylation. NBS1 then activates the MRE11-RAD50 nuclease through direct physical interactions with MRE11. In the absence of NBS1, MRE11-RAD50 exhibits a weaker nuclease activity, which requires CtIP but not strictly its phosphorylation. This identifies at least two mechanisms by which CtIP augments MRE11: a phosphorylation-dependent mode through NBS1 and a phosphorylation-independent mode without NBS1. In support, we show that limited DNA end resection occurs in vivo in the absence of the FHA and BRCT domains of NBS1. Collectively, our data suggest that NBS1 restricts the MRE11-RAD50 nuclease to S-G2 phase when CtIP is extensively phosphorylated. This defines mechanisms that regulate the MRE11 nuclease in DNA metabolism.
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Affiliation(s)
- Roopesh Anand
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona, Switzerland
| | - Arti Jasrotia
- Department of Gynecology, University of Zurich, Schlieren, Switzerland
| | - Diana Bundschuh
- Department of Gynecology, University of Zurich, Schlieren, Switzerland
| | - Sean Michael Howard
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona, Switzerland
| | - Lepakshi Ranjha
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona, Switzerland
| | - Manuel Stucki
- Department of Gynecology, University of Zurich, Schlieren, Switzerland
| | - Petr Cejka
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona, Switzerland
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
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12
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A Novel Aspect of Tumorigenesis-BMI1 Functions in Regulating DNA Damage Response. Biomolecules 2015; 5:3396-415. [PMID: 26633535 PMCID: PMC4693283 DOI: 10.3390/biom5043396] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 10/23/2015] [Accepted: 11/26/2015] [Indexed: 12/27/2022] Open
Abstract
BMI1 plays critical roles in maintaining the self-renewal of hematopoietic, neural, intestinal stem cells, and cancer stem cells (CSCs) for a variety of cancer types. BMI1 promotes cell proliferative life span and epithelial to mesenchymal transition (EMT). Upregulation of BMI1 occurs in multiple cancer types and is associated with poor prognosis. Mechanistically, BMI1 is a subunit of the Polycomb repressive complex 1 (PRC1), and binds the catalytic RING2/RING1b subunit to form a functional E3 ubiquitin ligase. Through mono-ubiquitination of histone H2A at lysine 119 (H2A-K119Ub), BMI1 represses multiple gene loci; among these, the INK4A/ARF locus has been most thoroughly investigated. The locus encodes the p16INK4A and p14/p19ARF tumor suppressors that function in the pRb and p53 pathways, respectively. Its repression contributes to BMI1-derived tumorigenesis. BMI1 also possesses other oncogenic functions, specifically its regulative role in DNA damage response (DDR). In this process, BMI1 ubiquitinates histone H2A and γH2AX, thereby facilitating the repair of double-stranded DNA breaks (DSBs) through stimulating homologous recombination and non-homologous end joining. Additionally, BMI1 compromises DSB-induced checkpoint activation independent of its-associated E3 ubiquitin ligase activity. We review the emerging role of BMI1 in DDR regulation and discuss its impact on BMI1-derived tumorigenesis.
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13
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Cao LL, Wei F, Du Y, Song B, Wang D, Shen C, Lu X, Cao Z, Yang Q, Gao Y, Wang L, Zhao Y, Wang H, Yang Y, Zhu WG. ATM-mediated KDM2A phosphorylation is required for the DNA damage repair. Oncogene 2015; 35:301-13. [DOI: 10.1038/onc.2015.81] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 01/21/2015] [Accepted: 02/22/2015] [Indexed: 12/25/2022]
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14
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Lafrance-Vanasse J, Williams GJ, Tainer JA. Envisioning the dynamics and flexibility of Mre11-Rad50-Nbs1 complex to decipher its roles in DNA replication and repair. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 117:182-193. [PMID: 25576492 PMCID: PMC4417436 DOI: 10.1016/j.pbiomolbio.2014.12.004] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 12/20/2014] [Accepted: 12/28/2014] [Indexed: 12/23/2022]
Abstract
The Mre11-Rad50-Nbs1 (MRN) complex is a dynamic macromolecular machine that acts in the first steps of DNA double strand break repair, and each of its components has intrinsic dynamics and flexibility properties that are directly linked with their functions. As a result, deciphering the functional structural biology of the MRN complex is driving novel and integrated technologies to define the dynamic structural biology of protein machinery interacting with DNA. Rad50 promotes dramatic long-range allostery through its coiled-coil and zinc-hook domains. Its ATPase activity drives dynamic transitions between monomeric and dimeric forms that can be modulated with mutants modifying the ATPase rate to control end joining versus resection activities. The biological functions of Mre11's dual endo- and exonuclease activities in repair pathway choice were enigmatic until recently, when they were unveiled by the development of specific nuclease inhibitors. Mre11 dimer flexibility, which may be regulated in cells to control MRN function, suggests new inhibitor design strategies for cancer intervention. Nbs1 has FHA and BRCT domains to bind multiple interaction partners that further regulate MRN. One of them, CtIP, modulates the Mre11 excision activity for homologous recombination repair. Overall, these combined properties suggest novel therapeutic strategies. Furthermore, they collectively help to explain how MRN regulates DNA repair pathway choice with implications for improving the design and analysis of cancer clinical trials that employ DNA damaging agents or target the DNA damage response.
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Affiliation(s)
| | | | - John A Tainer
- Life Science Division, 1 Cyclotron Road, Berkeley, CA 94720, USA; The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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15
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Gray K, Kumar S, Figg N, Harrison J, Baker L, Mercer J, Littlewood T, Bennett M. Effects of DNA damage in smooth muscle cells in atherosclerosis. Circ Res 2014; 116:816-26. [PMID: 25524056 DOI: 10.1161/circresaha.116.304921] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
RATIONALE DNA damage and the DNA damage response have been identified in human atherosclerosis, including in vascular smooth muscle cells (VSMCs). However, although double-stranded breaks (DSBs) are hypothesized to promote plaque progression and instability, in part, by promoting cell senescence, apoptosis, and inflammation, the direct effects of DSBs in VSMCs seen in atherogenesis are unknown. OBJECTIVE To determine the presence and effect of endogenous levels of DSBs in VSMCs on atherosclerosis. METHODS AND RESULTS Human atherosclerotic plaque VSMCs showed increased expression of multiple DNA damage response proteins in vitro and in vivo, particularly the MRE11/RAD50/NBS1 complex that senses DSB repair. Oxidative stress-induced DSBs were increased in plaque VSMCs, but DSB repair was maintained. To determine the effect of DSBs on atherosclerosis, we generated 2 novel transgenic mice lines expressing NBS1 or C-terminal deleted NBS1 only in VSMCs, and crossed them with apolipoprotein E(-/-) mice. SM22α-NBS1/apolipoprotein E(-/-) VSMCs showed enhanced DSB repair and decreased growth arrest and apoptosis, whereas SM22α-(ΔC)NBS1/apolipoprotein E(-/-) VSMCs showed reduced DSB repair and increased growth arrest and apoptosis. Accelerating or retarding DSB repair did not affect atherosclerosis extent or composition. However, VSMC DNA damage reduced relative fibrous cap areas, whereas accelerating DSB repair increased cap area and VSMC content. CONCLUSIONS Human atherosclerotic plaque VSMCs show increased DNA damage, including DSBs and DNA damage response activation. VSMC DNA damage has minimal effects on atherogenesis, but alters plaque phenotype inhibiting fibrous cap areas in advanced lesions. Inhibiting DNA damage in atherosclerosis may be a novel target to promote plaque stability.
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MESH Headings
- Animals
- Aorta/cytology
- Aorta/pathology
- Aortic Diseases/genetics
- Aortic Diseases/metabolism
- Aortic Diseases/pathology
- Apolipoproteins E/deficiency
- Brachiocephalic Trunk/pathology
- Carotid Arteries/cytology
- Cell Cycle Proteins/biosynthesis
- Cell Cycle Proteins/genetics
- Cells, Cultured
- Comet Assay
- DNA Breaks, Double-Stranded
- DNA Damage
- DNA Repair Enzymes/biosynthesis
- DNA Repair Enzymes/genetics
- DNA-Binding Proteins
- Female
- Gene Expression Profiling
- Humans
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Microfilament Proteins/biosynthesis
- Microfilament Proteins/genetics
- Muscle Proteins/biosynthesis
- Muscle Proteins/genetics
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/metabolism
- Nuclear Proteins/biosynthesis
- Nuclear Proteins/genetics
- Oligonucleotide Array Sequence Analysis
- Plaque, Atherosclerotic/genetics
- Plaque, Atherosclerotic/metabolism
- Plaque, Atherosclerotic/pathology
- Up-Regulation
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Affiliation(s)
- Kelly Gray
- From the Division of Cardiovascular Medicine (K.G., S.K., N.F., J.H., L.B., J.M., M.B.) and Department of Biochemistry (T.L.), Addenbrooke's Centre for Clinical Investigation, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Sheetal Kumar
- From the Division of Cardiovascular Medicine (K.G., S.K., N.F., J.H., L.B., J.M., M.B.) and Department of Biochemistry (T.L.), Addenbrooke's Centre for Clinical Investigation, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Nichola Figg
- From the Division of Cardiovascular Medicine (K.G., S.K., N.F., J.H., L.B., J.M., M.B.) and Department of Biochemistry (T.L.), Addenbrooke's Centre for Clinical Investigation, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - James Harrison
- From the Division of Cardiovascular Medicine (K.G., S.K., N.F., J.H., L.B., J.M., M.B.) and Department of Biochemistry (T.L.), Addenbrooke's Centre for Clinical Investigation, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Lauren Baker
- From the Division of Cardiovascular Medicine (K.G., S.K., N.F., J.H., L.B., J.M., M.B.) and Department of Biochemistry (T.L.), Addenbrooke's Centre for Clinical Investigation, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - John Mercer
- From the Division of Cardiovascular Medicine (K.G., S.K., N.F., J.H., L.B., J.M., M.B.) and Department of Biochemistry (T.L.), Addenbrooke's Centre for Clinical Investigation, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Trevor Littlewood
- From the Division of Cardiovascular Medicine (K.G., S.K., N.F., J.H., L.B., J.M., M.B.) and Department of Biochemistry (T.L.), Addenbrooke's Centre for Clinical Investigation, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Martin Bennett
- From the Division of Cardiovascular Medicine (K.G., S.K., N.F., J.H., L.B., J.M., M.B.) and Department of Biochemistry (T.L.), Addenbrooke's Centre for Clinical Investigation, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom.
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16
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Cilli D, Mirasole C, Pennisi R, Pallotta V, D'Alessandro A, Antoccia A, Zolla L, Ascenzi P, di Masi A. Identification of the interactors of human nibrin (NBN) and of its 26 kDa and 70 kDa fragments arising from the NBN 657del5 founder mutation. PLoS One 2014; 9:e114651. [PMID: 25485873 PMCID: PMC4259352 DOI: 10.1371/journal.pone.0114651] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 11/12/2014] [Indexed: 01/17/2023] Open
Abstract
Nibrin (also named NBN or NBS1) is a component of the MRE11/RAD50/NBN complex, which is involved in early steps of DNA double strand breaks sensing and repair. Mutations within the NBN gene are responsible for the Nijmegen breakage syndrome (NBS). The 90% of NBS patients are homozygous for the 657del5 mutation, which determines the synthesis of two truncated proteins of 26 kDa (p26) and 70 kDa (p70). Here, HEK293 cells have been exploited to transiently express either the full-length NBN protein or the p26 or p70 fragments, followed by affinity chromatography enrichment of the eluates. The application of an unsupervised proteomics approach, based upon SDS-PAGE separation and shotgun digestion of protein bands followed by MS/MS protein identification, indicates the occurrence of previously unreported protein interacting partners of the full-length NBN protein and the p26 fragment containing the FHA/BRCT1 domains, especially after cell irradiation. In particular, results obtained shed light on new possible roles of NBN and of the p26 fragment in ROS scavenging, in the DNA damage response, and in protein folding and degradation. In particular, here we show that p26 interacts with PARP1 after irradiation, and this interaction exerts an inhibitory effect on PARP1 activity as measured by NAD+ levels. Furthermore, the p26-PARP1 interaction seems to be responsible for the persistence of ROS, and in turn of DSBs, at 24 h from IR. Since some of the newly identified interactors of the p26 and p70 fragments have not been found to interact with the full-length NBN, these interactions may somehow contribute to the key biological phenomena underpinning NBS.
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Affiliation(s)
| | - Cristiana Mirasole
- Department of Ecological and Biological Sciences, University of Tuscia, Viterbo, Italy
| | - Rosa Pennisi
- Department of Science, Roma Tre University, Rome, Italy
| | - Valeria Pallotta
- Department of Ecological and Biological Sciences, University of Tuscia, Viterbo, Italy
| | - Angelo D'Alessandro
- Department of Ecological and Biological Sciences, University of Tuscia, Viterbo, Italy
| | - Antonio Antoccia
- Department of Science, Roma Tre University, Rome, Italy
- Istituto Nazionale Biostrutture e Biosistemi – Consorzio Interuniversitario, Rome, Italy
| | - Lello Zolla
- Department of Ecological and Biological Sciences, University of Tuscia, Viterbo, Italy
| | - Paolo Ascenzi
- Istituto Nazionale Biostrutture e Biosistemi – Consorzio Interuniversitario, Rome, Italy
- Interdepartmental Laboratory for Electron Microscopy, Roma Tre University, Rome, Italy
| | - Alessandra di Masi
- Department of Science, Roma Tre University, Rome, Italy
- Istituto Nazionale Biostrutture e Biosistemi – Consorzio Interuniversitario, Rome, Italy
- * E-mail:
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17
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The MRE11 complex: An important source of stress relief. Exp Cell Res 2014; 329:162-9. [DOI: 10.1016/j.yexcr.2014.10.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 10/01/2014] [Accepted: 10/06/2014] [Indexed: 12/11/2022]
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18
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Structural studies of DNA end detection and resection in homologous recombination. Cold Spring Harb Perspect Biol 2014; 6:a017962. [PMID: 25081516 DOI: 10.1101/cshperspect.a017962] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
DNA double-strand breaks are repaired by two major pathways, homologous recombination or nonhomologous end joining. The commitment to one or the other pathway proceeds via different steps of resection of the DNA ends, which is controlled and executed by a set of DNA double-strand break sensors, endo- and exonucleases, helicases, and DNA damage response factors. The molecular choreography of the underlying protein machinery is beginning to emerge. In this review, we discuss the early steps of genetic recombination and double-strand break sensing with an emphasis on structural and molecular studies.
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19
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Schröder-Heurich B, Bogdanova N, Wieland B, Xie X, Noskowicz M, Park-Simon TW, Hillemanns P, Christiansen H, Dörk T. Functional deficiency of NBN, the Nijmegen breakage syndrome protein, in a p.R215W mutant breast cancer cell line. BMC Cancer 2014; 14:434. [PMID: 24928521 PMCID: PMC4085727 DOI: 10.1186/1471-2407-14-434] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 05/26/2014] [Indexed: 12/17/2022] Open
Abstract
Background Mutations in NBN, the gene for Nijmegen Breakage Syndrome (NBS), are thought to predispose women to developing breast cancer, but a breast cancer cell line containing mutations in NBN has not yet been described. The p.R215W missense mutation occurs at sub-polymorphic frequencies in several populations. We aimed to investigate its functional impact in breast cancer cells from a carrier of this NBN mutation. Methods Breast cancer cell lines were screened by immunoblotting for NBN protein levels, and the NBN coding region was sequenced for mutation analysis. Radiosensitivity assays and functional studies were performed through immunocytochemistry and immunoblotting, and flow cytometry was employed to assess cell cycle progression. Impedance measurements were used to study the consequences of PARP1 inhibition. Statistical comparisons between cell lines were performed using t-tests. Results HCC1395 breast cancer cells exhibited reduced NBN protein levels. Direct sequencing identified the NBN p.R215W mutation in the hemizygous state, in addition to a truncation in BRCA1. Mutations in both genes were already present in the heterozygous state in the patient’s germline. HCC1395 cells were highly radiosensitive, susceptible to apoptosis and were deficient in the formation of NBN foci. There was also evidence for some impairment in the formation of γH2AX, MDC1, and 53BP1 foci after irradiation; these foci appeared smaller and irregular compared with repair foci in wild-type cells, although ATM signalling was largely unaffected. In line with their deficiency in NBN and BRCA1, HCC1395 cells were particularly sensitive to PARP1 inhibition. Conclusion Our results indicate that the p.R215W mutation in the HCC1395 breast cancer cell line impairs NBN function, making this cell line a potentially useful cellular model for studying defective NBN protein within a mutant BRCA1 background.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Thilo Dörk
- Clinics of Obstetrics and Gynaecology, Hannover Medical School, Carl-Neuberg Straße 1, D-30625 Hannover, Germany.
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20
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Schröder-Heurich B, Wieland B, Lavin MF, Schindler D, Dörk T. Protective role of RAD50 on chromatin bridges during abnormal cytokinesis. FASEB J 2013; 28:1331-41. [PMID: 24344331 DOI: 10.1096/fj.13-236984] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Faithful chromosome segregation is required for preserving genomic integrity. Failure of this process may entail chromatin bridges preventing normal cytokinesis. To test whether RAD50, a protein normally involved in DNA double-strand break repair, is involved in abnormal cytokinesis and formation of chromatin bridges, we used immunocytochemical and protein interaction assays. RAD50 localizes to chromatin bridges during aberrant cytokinesis and subsequent stages of the cell cycle, either decorating the entire bridge or focally accumulating at the midbody zone. Ionizing radiation led to an ∼4-fold increase in the rate of chromatin bridges in an ataxia telangiectatica mutated (ATM)-dependent manner in human RAD50-proficient fibroblasts but not in RAD50-deficient cells. Cells with a RAD50-positive chromatin bridge were able to continue cell cycling and to progress through S phase (44%), whereas RAD50 knockdown caused a deficiency in chromatin bridges as well as an ∼4-fold prolonged duration of mitosis. RAD50 colocalized and directly interacted with Aurora B kinase and phospho-histone H3, and Aurora B kinase inhibition led to a deficiency in RAD50-positive bridges. Based on these observations, we propose that RAD50 is a crucial factor for the stabilization and shielding of chromatin bridges. Our study provides evidence for a hitherto unknown role of RAD50 in abnormal cytokinesis.
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Affiliation(s)
- Bianca Schröder-Heurich
- 1Hannover Medical School, Gynaecology Research Unit (OE 6411), Carl-Neuberg-Str. 1, D-30625 Hannover, Germany.
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21
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Mermershtain I, Glover JNM. Structural mechanisms underlying signaling in the cellular response to DNA double strand breaks. Mutat Res 2013; 750:15-22. [PMID: 23896398 DOI: 10.1016/j.mrfmmm.2013.07.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 07/12/2013] [Accepted: 07/16/2013] [Indexed: 01/04/2023]
Abstract
DNA double strand breaks (DSBs) constitute one of the most dangerous forms of DNA damage. In actively replicating cells, these breaks are first recognized by specialized proteins that initiate a signal transduction cascade that modulates the cell cycle and results in the repair of the breaks by homologous recombination (HR). Protein signaling in response to double strand breaks involves phosphorylation and ubiquitination of chromatin and a variety of associated proteins. Here we review the emerging structural principles that underlie how post-translational protein modifications control protein signaling that emanates from these DNA lesions.
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Affiliation(s)
- Inbal Mermershtain
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
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22
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Abstract
Ataxia-telangiectasia (A-T) has for a long time stood apart from most other human neurodegenerative syndromes by the characteristic failure of cells derived from these patients to properly repair DNA damage-induced by ionizing radiation. The discovery of mutations in the ATM gene as being the underlying cause for A-T and the demonstration that the ATM protein functions as a DNA damage-responsive kinase has defined current research focusing on decoding how the cell responds to genotoxic stress. Yet, despite significant advances in delineating the cellular DNA damage response pathways coordinated by ATM, very little headway has been made toward understanding how loss of ATM leads to progressive cerebellar ataxia and whether this can be attributed to an underlying defect in DNA double strand break repair (DSBR). Since its identification, A-T has been used as the archetypal model for how a deficiency in DNA repair affects both the development and maintenance of the nervous and immune systems in humans as well as contributing to the process of tumourigenesis. However, following the growing availability and cost effectiveness of next generation sequencing technologies, the increasing recognition of novel human disorders associated with abnormal DNA repair has demonstrated that the neuropathology typified by A-T is an 'exception' rather than the 'rule'. As a consequence, this throws into doubt the longstanding hypothesis that the neurodegeneration seen in A-T is due to the progressive loss of damaged neurons that have acquired toxic levels of unrepaired DNA lesions over time. Therefore, this review aims to address the question: Is defective DNA double strand break repair an underlying cause of neurodegeneration?
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23
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Wang H, Shi LZ, Wong CCL, Han X, Hwang PYH, Truong LN, Zhu Q, Shao Z, Chen DJ, Berns MW, Yates JR, Chen L, Wu X. The interaction of CtIP and Nbs1 connects CDK and ATM to regulate HR-mediated double-strand break repair. PLoS Genet 2013; 9:e1003277. [PMID: 23468639 PMCID: PMC3585124 DOI: 10.1371/journal.pgen.1003277] [Citation(s) in RCA: 190] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 12/12/2012] [Indexed: 11/19/2022] Open
Abstract
CtIP plays an important role in homologous recombination (HR)-mediated DNA double-stranded break (DSB) repair and interacts with Nbs1 and BRCA1, which are linked to Nijmegen breakage syndrome (NBS) and familial breast cancer, respectively. We identified new CDK phosphorylation sites on CtIP and found that phosphorylation of these newly identified CDK sites induces association of CtIP with the N-terminus FHA and BRCT domains of Nbs1. We further showed that these CDK-dependent phosphorylation events are a prerequisite for ATM to phosphorylate CtIP upon DNA damage, which is important for end resection to activate HR by promoting recruitment of BLM and Exo1 to DSBs. Most notably, this CDK-dependent CtIP and Nbs1 interaction facilitates ATM to phosphorylate CtIP in a substrate-specific manner. These studies reveal one important mechanism to regulate cell-cycle-dependent activation of HR upon DNA damage by coupling CDK- and ATM-mediated phosphorylation of CtIP through modulating the interaction of CtIP with Nbs1, which significantly helps to understand how DSB repair is regulated in mammalian cells to maintain genome stability.
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Affiliation(s)
- Hailong Wang
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, United States of America
| | - Linda Z. Shi
- The Institute of Engineering in Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Catherine C. L. Wong
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Xuemei Han
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Patty Yi-Hwa Hwang
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, United States of America
| | - Lan N. Truong
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, United States of America
| | - Qingyuan Zhu
- The Institute of Engineering in Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Zhengping Shao
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - David J. Chen
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Michael W. Berns
- The Institute of Engineering in Medicine, University of California San Diego, La Jolla, California, United States of America
| | - John R. Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Longchuan Chen
- Department of Pathology, Veterans Affairs Medical Center, Long Beach, California, United States of America
| | - Xiaohua Wu
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, United States of America
- * E-mail:
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24
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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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25
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Silva J, Teixeira AL, Lobo F, Maurício J, Medeiros R. DNA repair system and prostate cancer progression: the role of NBS1 polymorphism (rs1805794). DNA Cell Biol 2012; 31:1182-6. [PMID: 22413803 DOI: 10.1089/dna.2011.1562] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
NBS1 plays an important role in the maintenance of genomic integrity, by being involved in cellular response to DNA damage. The NBS1 rs1805794 G>C polymorphism has been investigated in several studies, but its function still remains unclear due to some controversial results. The present work aimed to evaluate the role of this polymorphism in prostate cancer progression, by performing a case-control study comparing 239 patients who were diagnosed with early disease to 186 who presented advanced disease. We also assessed NBS1 mRNA expression among the different groups by quantitative real time (qRT)-polymerase chain reaction. We found that the GG carriers presented an almost two fold increased risk for advanced prostate disease (odds ratio [OR] = 1.87; confidence interval [CI] = 1.26-2.79; p = 0.002). Further, high tumor grade (OR = 3.02; CI = 2.32-3.92; p<0.001) and high serum prostate specific antigen (PSA) (OR = 6.48; CI = 4.48-9.38; p<0.001) were consistently associated to advanced disease. Regarding NBS1 mRNA expression, we did not find any association with the different outcomes nor genotypes (p = 0.926; p = 0.894, respectively). Our results suggest for the first time that rs1805794 GG genotype appears to be associated with a higher risk for advanced prostate cancer, thus, suggesting a possible new role for NBS1 in prostate cancer progression.
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Affiliation(s)
- Joana Silva
- Molecular Oncology GRP & Virology, Portuguese Institute of Oncology, Porto, Portugal
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26
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Polo SE, Blackford AN, Chapman JR, Baskcomb L, Gravel S, Rusch A, Thomas A, Blundred R, Smith P, Kzhyshkowska J, Dobner T, Taylor AMR, Turnell AS, Stewart GS, Grand RJ, Jackson SP. Regulation of DNA-end resection by hnRNPU-like proteins promotes DNA double-strand break signaling and repair. Mol Cell 2012; 45:505-16. [PMID: 22365830 PMCID: PMC3550743 DOI: 10.1016/j.molcel.2011.12.035] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 08/26/2011] [Accepted: 12/13/2011] [Indexed: 01/19/2023]
Abstract
DNA double-strand break (DSB) signaling and repair are critical for cell viability, and rely on highly coordinated pathways whose molecular organization is still incompletely understood. Here, we show that heterogeneous nuclear ribonucleoprotein U-like (hnRNPUL) proteins 1 and 2 play key roles in cellular responses to DSBs. We identify human hnRNPUL1 and -2 as binding partners for the DSB sensor complex MRE11-RAD50-NBS1 (MRN) and demonstrate that hnRNPUL1 and -2 are recruited to DNA damage in an interdependent manner that requires MRN. Moreover, we show that hnRNPUL1 and -2 stimulate DNA-end resection and promote ATR-dependent signaling and DSB repair by homologous recombination, thereby contributing to cell survival upon exposure to DSB-inducing agents. Finally, we establish that hnRNPUL1 and -2 function downstream of MRN and CtBP-interacting protein (CtIP) to promote recruitment of the BLM helicase to DNA breaks. Collectively, these results provide insights into how mammalian cells respond to DSBs.
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Affiliation(s)
- Sophie E. Polo
- The Gurdon Institute, Department of Biochemistry, University of Cambridge, Cambridge CB2 1QN, UK
| | - Andrew N. Blackford
- Cancer Research UK School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - J. Ross Chapman
- The Gurdon Institute, Department of Biochemistry, University of Cambridge, Cambridge CB2 1QN, UK
| | - Linda Baskcomb
- The Gurdon Institute, Department of Biochemistry, University of Cambridge, Cambridge CB2 1QN, UK
| | - Serge Gravel
- The Gurdon Institute, Department of Biochemistry, University of Cambridge, Cambridge CB2 1QN, UK
| | - Andre Rusch
- Heinrich Pette Institute for Experimental Virology and Immunology, 20251 Hamburg, Germany
| | - Anoushka Thomas
- Cancer Research UK School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Rachel Blundred
- Cancer Research UK School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Philippa Smith
- The Gurdon Institute, Department of Biochemistry, University of Cambridge, Cambridge CB2 1QN, UK
| | - Julia Kzhyshkowska
- Medical Faculty Mannheim, Ruprecht-Karls University of Heidelberg, 68167 Mannheim, Germany, and Institute of General Pathology and Pathophysiology, Russian Academy of Medical Sciences, 125 315 Moscow, Russia
| | - Thomas Dobner
- Heinrich Pette Institute for Experimental Virology and Immunology, 20251 Hamburg, Germany
| | - A. Malcolm R. Taylor
- Cancer Research UK School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Andrew S. Turnell
- Cancer Research UK School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Grant S. Stewart
- Cancer Research UK School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Roger J. Grand
- Cancer Research UK School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Stephen P. Jackson
- The Gurdon Institute, Department of Biochemistry, University of Cambridge, Cambridge CB2 1QN, UK
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27
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Dzikiewicz-Krawczyk A, Mosor M, Januszkiewicz D, Nowak J. Impact of heterozygous c.657-661del, p.I171V and p.R215W mutations in NBN on nibrin functions. Mutagenesis 2011; 27:337-43. [PMID: 22131123 DOI: 10.1093/mutage/ger084] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Nibrin, product of the NBN gene, together with MRE11 and RAD50 is involved in DNA double-strand breaks (DSBs) sensing and repair, induction of apoptosis and cell cycle control. Biallelic NBN mutations cause the Nijmegen breakage syndrome, a chromosomal instability disorder characterised by, among other things, radiosensitivity, immunodeficiency and an increased cancer risk. Several studies have shown an association of heterozygous c.657-661del, p.I171V and p.R215W mutations in the NBN gene with a variety of malignancies but the data are controversial. Little is known, however, whether and to what extent do these mutations in heterozygous state affect nibrin functions. We examined frequency of chromatid breaks, DSB repair, defects in S-phase checkpoint and radiosensitivity in X-ray-irradiated cells from control individuals, NBS patients and heterozygous carriers of the c.657-661del, p.I171V and p.R215W mutations. While cells homozygous for c.657-661del displayed a significantly increased number of chromatid breaks and residual γ-H2AX foci, as well as abrogation of the intra-S-phase checkpoint following irradiation, which resulted in increased radiosensitivity, cells with heterozygous c.657-661del, p.I171V and p.R215W mutations behaved similarly to control cells. Significant differences in the frequency of spontaneous and ionising radiation-induced chromatid breaks and the level of persistent γ-H2AX foci were observed when comparing control and mutant cells heterozygous for c.657-661del. However, it is still possible that heterozygous NBN mutations may contribute to cancer development.
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28
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Abstract
BRCA1 C-terminal (BRCT) domains are integral signaling modules in the DNA damage response (DDR). Aside from their established roles as phospho-peptide binding modules, BRCT domains have been implicated in phosphorylation-independent protein interactions, DNA binding and poly(ADP-ribose) (PAR) binding. These numerous functions can be attributed to the diversity in BRCT domain structure and architecture, where domains can exist as isolated single domains or assemble into higher order homo- or hetero- domain complexes. In this review, we incorporate recent structural and biochemical studies to demonstrate how structural features allow single and tandem BRCT domains to attain a high degree of functional diversity.
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29
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Polo SE, Jackson SP. Dynamics of DNA damage response proteins at DNA breaks: a focus on protein modifications. Genes Dev 2011; 25:409-33. [PMID: 21363960 DOI: 10.1101/gad.2021311] [Citation(s) in RCA: 837] [Impact Index Per Article: 64.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Genome integrity is constantly monitored by sophisticated cellular networks, collectively termed the DNA damage response (DDR). A common feature of DDR proteins is their mobilization in response to genotoxic stress. Here, we outline how the development of various complementary methodologies has provided valuable insights into the spatiotemporal dynamics of DDR protein assembly/disassembly at sites of DNA strand breaks in eukaryotic cells. Considerable advances have also been made in understanding the underlying molecular mechanisms for these events, with post-translational modifications of DDR factors being shown to play prominent roles in controlling the formation of foci in response to DNA-damaging agents. We review these regulatory mechanisms and discuss their biological significance to the DDR.
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Affiliation(s)
- Sophie E Polo
- The Gurdon Institute, Department of Biochemistry, University of Cambridge, Cambridge CB21QN, United Kingdom
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30
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Williams GJ, Lees-Miller SP, Tainer JA. Mre11-Rad50-Nbs1 conformations and the control of sensing, signaling, and effector responses at DNA double-strand breaks. DNA Repair (Amst) 2010; 9:1299-306. [PMID: 21035407 PMCID: PMC3008338 DOI: 10.1016/j.dnarep.2010.10.001] [Citation(s) in RCA: 158] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/30/2010] [Indexed: 10/18/2022]
Abstract
Repair and integrity of DNA ends at breaks, replication forks and telomeres are essential for life; yet, paradoxically, these responses are, in many cases, controlled by a single protein complex, Mre11-Rad50-Nbs1 (MRN). The MRN complex consists of dimers of each subunit and this heterohexamer controls key sensing, signaling, regulation, and effector responses to DNA double-strand breaks including ATM activation, homologous recombinational repair, microhomology-mediated end joining and, in some organisms, non-homologous end joining. We propose that this is possible because each MRN subunit can exist in three or more distinct states; thus, the trimer of MRN dimers can exist in a stunning 6(3) or 216 states, a number that can be expanded further when post-translational modifications are taken into account. MRN can therefore be considered as a molecular computer that effectively assesses optimal responses and pathway choice based upon its states as set by cell status and the nature of the DNA damage. This extreme multi-state concept demands a paradigm shift from striving to understand DNA damage responses in separate terms of signaling, checkpoint, and effector proteins: we must now endeavor to characterize conformational and assembly states of MRN and other DNA repair machines that couple, coordinate, and control biological outcomes. Addressing the emerging challenge of gaining a detailed molecular understanding of MRN and other multi-state dynamic DNA repair machines promises to provide opportunities to develop master keys for controlling cell biology with probable impacts on therapeutic interventions.
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Affiliation(s)
- Gareth J. Williams
- Life Sciences Division, Department of Molecular Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Susan P. Lees-Miller
- Department of Biochemistry and Molecular Biology and the Southern Alberta Cancer Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - John A. Tainer
- Life Sciences Division, Department of Molecular Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Molecular Biology, Skaggs Institute of Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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31
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Bekker-Jensen S, Mailand N. Assembly and function of DNA double-strand break repair foci in mammalian cells. DNA Repair (Amst) 2010; 9:1219-28. [PMID: 21035408 DOI: 10.1016/j.dnarep.2010.09.010] [Citation(s) in RCA: 267] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/16/2010] [Indexed: 12/16/2022]
Abstract
DNA double-strand breaks (DSBs) are among the most cytotoxic types of DNA damage, which if left unrepaired can lead to mutations or gross chromosomal aberrations, and promote the onset of diseases associated with genomic instability such as cancer. One of the most discernible hallmarks of the cellular response to DSBs is the accumulation and local concentration of a plethora of DNA damage signaling and repair proteins in the vicinity of the lesion, initiated by ATM-mediated phosphorylation of H2AX (γ-H2AX) and culminating in the generation of distinct nuclear compartments, so-called Ionizing Radiation-Induced Foci (IRIF). The assembly of proteins at the DSB-flanking chromatin occurs in a highly ordered and strictly hierarchical fashion. To a large extent, this is achieved by regulation of protein-protein interactions triggered by a variety of post-translational modifications including phosphorylation, ubiquitylation, SUMOylation, and acetylation. Over the last decade, insight into the identity of proteins residing in IRIF and the molecular underpinnings of their retention at these structures has been vastly expanded. Despite such advances, however, our understanding of the biological relevance of such DNA repair foci still remains limited. In this review, we focus on recent discoveries on the mechanisms that govern the formation of IRIF, and discuss the implications of such findings in light of our understanding of the physiological importance of these structures.
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Affiliation(s)
- Simon Bekker-Jensen
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
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