1
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Bedir M, Outwin E, Colnaghi R, Bassett L, Abramowicz I, O'Driscoll M. A novel role for the peptidyl-prolyl cis-trans isomerase Cyclophilin A in DNA-repair following replication fork stalling via the MRE11-RAD50-NBS1 complex. EMBO Rep 2024:10.1038/s44319-024-00184-9. [PMID: 38943005 DOI: 10.1038/s44319-024-00184-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 05/28/2024] [Accepted: 06/05/2024] [Indexed: 06/30/2024] Open
Abstract
Cyclosporin A (CsA) induces DNA double-strand breaks in LIG4 syndrome fibroblasts, specifically upon transit through S-phase. The basis underlying this has not been described. CsA-induced genomic instability may reflect a direct role of Cyclophilin A (CYPA) in DNA repair. CYPA is a peptidyl-prolyl cis-trans isomerase (PPI). CsA inhibits the PPI activity of CYPA. Using an integrated approach involving CRISPR/Cas9-engineering, siRNA, BioID, co-immunoprecipitation, pathway-specific DNA repair investigations as well as protein expression interaction analysis, we describe novel impacts of CYPA loss and inhibition on DNA repair. We characterise a direct CYPA interaction with the NBS1 component of the MRE11-RAD50-NBS1 complex, providing evidence that CYPA influences DNA repair at the level of DNA end resection. We define a set of genetic vulnerabilities associated with CYPA loss and inhibition, identifying DNA replication fork protection as an important determinant of viability. We explore examples of how CYPA inhibition may be exploited to selectively kill cancers sharing characteristic genomic instability profiles, including MYCN-driven Neuroblastoma, Multiple Myeloma and Chronic Myelogenous Leukaemia. These findings propose a repurposing strategy for Cyclophilin inhibitors.
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Affiliation(s)
- Marisa Bedir
- Human DNA Damage Response Disorders Group, Genome Damage & Stability Centre, University of Sussex, Brighton, BN1 9RQ, UK
| | - Emily Outwin
- Human DNA Damage Response Disorders Group, Genome Damage & Stability Centre, University of Sussex, Brighton, BN1 9RQ, UK
| | - Rita Colnaghi
- Human DNA Damage Response Disorders Group, Genome Damage & Stability Centre, University of Sussex, Brighton, BN1 9RQ, UK
| | - Lydia Bassett
- Human DNA Damage Response Disorders Group, Genome Damage & Stability Centre, University of Sussex, Brighton, BN1 9RQ, UK
| | - Iga Abramowicz
- Human DNA Damage Response Disorders Group, Genome Damage & Stability Centre, University of Sussex, Brighton, BN1 9RQ, UK
| | - Mark O'Driscoll
- Human DNA Damage Response Disorders Group, Genome Damage & Stability Centre, University of Sussex, Brighton, BN1 9RQ, UK.
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2
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Lokanathan Balaji S, De Bragança S, Balaguer-Pérez F, Northall S, Wilkinson OJ, Aicart-Ramos C, Seetaloo N, Sobott F, Moreno-Herrero F, Dillingham MS. DNA binding and bridging by human CtIP in the healthy and diseased states. Nucleic Acids Res 2024:gkae538. [PMID: 38922686 DOI: 10.1093/nar/gkae538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 06/05/2024] [Accepted: 06/13/2024] [Indexed: 06/28/2024] Open
Abstract
The human DNA repair factor CtIP helps to initiate the resection of double-stranded DNA breaks for repair by homologous recombination, in part through its ability to bind and bridge DNA molecules. However, CtIP is a natively disordered protein that bears no apparent similarity to other DNA-binding proteins and so the structural basis for these activities remains unclear. In this work, we have used bulk DNA binding, single molecule tracking, and DNA bridging assays to study wild-type and variant CtIP proteins to better define the DNA binding domains and the effects of mutations associated with inherited human disease. Our work identifies a monomeric DNA-binding domain in the C-terminal region of CtIP. CtIP binds non-specifically to DNA and can diffuse over thousands of nucleotides. CtIP-mediated bridging of distant DNA segments is observed in single-molecule magnetic tweezers experiments. However, we show that binding alone is insufficient for DNA bridging, which also requires tetramerization via the N-terminal domain. Variant CtIP proteins associated with Seckel and Jawad syndromes display impaired DNA binding and bridging activities. The significance of these findings in the context of facilitating DNA break repair is discussed.
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Affiliation(s)
- Shreya Lokanathan Balaji
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Sara De Bragança
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049, Spain
| | - Francisco Balaguer-Pérez
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049, Spain
| | - Sarah Northall
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Oliver John Wilkinson
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Clara Aicart-Ramos
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049, Spain
| | - Neeleema Seetaloo
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Frank Sobott
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Fernando Moreno-Herrero
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049, Spain
| | - Mark Simon Dillingham
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
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3
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Khayat F, Alshmery M, Pal M, Oliver AW, Bianchi A. Binding of the TRF2 iDDR motif to RAD50 highlights a convergent evolutionary strategy to inactivate MRN at telomeres. Nucleic Acids Res 2024:gkae509. [PMID: 38884214 DOI: 10.1093/nar/gkae509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 05/07/2024] [Accepted: 06/07/2024] [Indexed: 06/18/2024] Open
Abstract
Telomeres protect chromosome ends from unscheduled DNA repair, including from the MRN (MRE11, RAD50, NBS1) complex, which processes double-stranded DNA breaks (DSBs) via activation of the ATM kinase, promotes DNA end-tethering aiding the non-homologous end-joining (NHEJ) pathway, and initiates DSB resection through the MRE11 nuclease. A protein motif (MIN, for MRN inhibitor) inhibits MRN at budding yeast telomeres by binding to RAD50 and evolved at least twice, in unrelated telomeric proteins Rif2 and Taz1. We identify the iDDR motif of human shelterin protein TRF2 as a third example of convergent evolution for this telomeric mechanism for binding MRN, despite the iDDR lacking sequence homology to the MIN motif. CtIP is required for activation of MRE11 nuclease action, and we provide evidence for binding of a short C-terminal region of CtIP to a RAD50 interface that partly overlaps with the iDDR binding site, indicating that the interaction is mutually exclusive. In addition, we show that the iDDR impairs the DNA binding activity of RAD50. These results highlight direct inhibition of MRN action as a crucial role of telomeric proteins across organisms and point to multiple mechanisms enforced by the iDDR to disable the many activities of the MRN complex.
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Affiliation(s)
- Freddy Khayat
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
| | - Majedh Alshmery
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
- Department of Life Sciences, Hafr Al Batin University, Saudi Arabia
| | - Mohinder Pal
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
- School of Biosciences, University of Kent, Canterbury, UK
| | - Antony W Oliver
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
| | - Alessandro Bianchi
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
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4
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Gao H, Xi Z, Dai J, Xue J, Guan X, Zhao L, Chen Z, Xing F. Drug resistance mechanisms and treatment strategies mediated by Ubiquitin-Specific Proteases (USPs) in cancers: new directions and therapeutic options. Mol Cancer 2024; 23:88. [PMID: 38702734 PMCID: PMC11067278 DOI: 10.1186/s12943-024-02005-y] [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: 02/03/2024] [Accepted: 04/16/2024] [Indexed: 05/06/2024] Open
Abstract
Drug resistance represents a significant obstacle in cancer treatment, underscoring the need for the discovery of novel therapeutic targets. Ubiquitin-specific proteases (USPs), a subclass of deubiquitinating enzymes, play a pivotal role in protein deubiquitination. As scientific research advances, USPs have been recognized as key regulators of drug resistance across a spectrum of treatment modalities, including chemotherapy, targeted therapy, immunotherapy, and radiotherapy. This comprehensive review examines the complex relationship between USPs and drug resistance mechanisms, focusing on specific treatment strategies and highlighting the influence of USPs on DNA damage repair, apoptosis, characteristics of cancer stem cells, immune evasion, and other crucial biological functions. Additionally, the review highlights the potential clinical significance of USP inhibitors as a means to counter drug resistance in cancer treatment. By inhibiting particular USP, cancer cells can become more susceptible to a variety of anti-cancer drugs. The integration of USP inhibitors with current anti-cancer therapies offers a promising strategy to circumvent drug resistance. Therefore, this review emphasizes the importance of USPs as viable therapeutic targets and offers insight into fruitful directions for future research and drug development. Targeting USPs presents an effective method to combat drug resistance across various cancer types, leading to enhanced treatment strategies and better patient outcomes.
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Affiliation(s)
- Hongli Gao
- Department of Oncology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Zhuo Xi
- Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Jingwei Dai
- Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Jinqi Xue
- Department of Oncology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Xin Guan
- Department of Gastroenterology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Liang Zhao
- Department of General Surgery, Shengjing Hospital of China Medical University, Shenyang, 110004, China.
| | - Zhiguang Chen
- Department of Emergency Medicine, Shengjing Hospital of China Medical University, Shenyang, 110004, China.
| | - Fei Xing
- Department of Oncology, Shengjing Hospital of China Medical University, Shenyang, 110004, China.
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5
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De Bragança S, Dillingham MS, Moreno-Herrero F. Recent insights into eukaryotic double-strand DNA break repair unveiled by single-molecule methods. Trends Genet 2023; 39:924-940. [PMID: 37806853 DOI: 10.1016/j.tig.2023.09.004] [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: 06/14/2023] [Revised: 09/04/2023] [Accepted: 09/07/2023] [Indexed: 10/10/2023]
Abstract
Genome integrity and maintenance are essential for the viability of all organisms. A wide variety of DNA damage types have been described, but double-strand breaks (DSBs) stand out as one of the most toxic DNA lesions. Two major pathways account for the repair of DSBs: homologous recombination (HR) and non-homologous end joining (NHEJ). Both pathways involve complex DNA transactions catalyzed by proteins that sequentially or cooperatively work to repair the damage. Single-molecule methods allow visualization of these complex transactions and characterization of the protein:DNA intermediates of DNA repair, ultimately allowing a comprehensive breakdown of the mechanisms underlying each pathway. We review current understanding of the HR and NHEJ responses to DSBs in eukaryotic cells, with a particular emphasis on recent advances through the use of single-molecule techniques.
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Affiliation(s)
- Sara De Bragança
- Department of Macromolecular Structures, Centro Nacional de Biotecnología (CNB), CSIC, Madrid, Spain
| | - Mark S Dillingham
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Fernando Moreno-Herrero
- Department of Macromolecular Structures, Centro Nacional de Biotecnología (CNB), CSIC, Madrid, Spain.
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6
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Batool T, Irshad S, Riaz M, Mahmood Baig S, Nuernberg P, Hussain MS. Recurrence mutation in RBBP8 gene causing non-syndromic autosomal recessive primary microcephaly; geometric simulation approach for insight into predicted computational models. J Hum Genet 2023; 68:469-475. [PMID: 36864288 DOI: 10.1038/s10038-023-01132-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 01/18/2023] [Accepted: 02/06/2023] [Indexed: 03/04/2023]
Abstract
Primary microcephaly is a rare, congenital, and genetically heterogeneous disorder in which occipitofrontal head circumference is reduced by a minimum of three standard deviations (SDs) from average because of the defect in fetal brain development. OBJECTIVE Mapping of RBBP8 gene mutation that produce autosomal recessive primary microcephaly. Insilco RBBP8 protein models prediction and analysis. METHODS Consanguineous Pakistani family affected with non-syndromic primary microcephaly was mapped a biallelic sequence variant (c.1807_1808delAT) in the RBBP8 gene via whole-exome sequencing. The deleted variant in the RBBP8 gene in affected siblings (V:4, V:6) of primary microcephaly was confirmed by sanger sequencing. RESULTS Identified variant c.1807_1808delAT that truncated the protein translation p. Ile603Lysfs*7 and impaired the functioning of RBBP8 protein. This sequence variant was only reported previously in Atypical Seckel syndrome and Jawad syndrome, while we mapped it in the non-syndromic primary microcephaly family. We predicted 3D protein models by using Insilco tools like I TASSER, Swiss model, and phyre2 of wild RBBP8 protein of 897 amino acids and 608 amino acids of the mutant protein. These models were validated through the online SAVES server and Ramachandran plot and refined by using the Galaxy WEB server. A predicted and refined wild protein 3D model was deposited with accession number PM0083523 in Protein Model Database. A normal mode-based geometric simulation approach was used through the NMSim program, to find out the structural diversity of wild and mutant proteins which were evaluated by RMSD and RMSF. Higher RMSD and RMSF in mutant protein reduced the stability of the protein. CONCLUSION The high possibility of this variant results in nonsense-mediated decay of mRNA, leading to the loss of protein functioning which causes primary microcephaly.
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Affiliation(s)
- Tahira Batool
- School of Biochemistry and Biotechnology (SBB), University of the Punjab, Lahore-54590, Pakistan
| | - Saba Irshad
- School of Biochemistry and Biotechnology (SBB), University of the Punjab, Lahore-54590, Pakistan.
| | - Muhammad Riaz
- Department of Allied Health Sciences, University of Sargodha, Sargodha, 40100, Pakistan
| | | | - Peter Nuernberg
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, 50931, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, 50931, Cologne, Germany
| | - Muhammad Sajid Hussain
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, 50931, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, 50931, Cologne, Germany
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7
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Wojtaszek JL, Williams RS. The ends in sight: Mre11-Rad50-Nbs1 complex structures come into focus. Mol Cell 2023; 83:160-162. [PMID: 36669476 DOI: 10.1016/j.molcel.2022.12.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 12/15/2022] [Accepted: 12/15/2022] [Indexed: 01/20/2023]
Abstract
In this issue of Molecular Cell, Rotheneder et al.1 elucidate the eukaroytic Mre11-Rad50-Nbs1 (MRN) complex quaternary architecture, which together with cryo-EM structures of bacterial Mre11-Rad50-DNA complexes,2 resolves the basis for MRN assembly and its broad nuclease specificity regulating DNA double-strand break repair.
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Affiliation(s)
- Jessica L Wojtaszek
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, Durham, Research Triangle Park, NC 27709, USA
| | - R Scott Williams
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, Durham, Research Triangle Park, NC 27709, USA.
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8
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Kim SH, Kim GH, Kemp MG, Choi JH. TREX1 degrades the 3' end of the small DNA oligonucleotide products of nucleotide excision repair in human cells. Nucleic Acids Res 2022; 50:3974-3984. [PMID: 35357486 PMCID: PMC9023299 DOI: 10.1093/nar/gkac214] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 03/02/2022] [Accepted: 03/18/2022] [Indexed: 01/01/2023] Open
Abstract
The nucleotide excision repair (NER) machinery removes UV photoproducts from DNA in the form of small, excised damage-containing DNA oligonucleotides (sedDNAs) ∼30 nt in length. How cells process and degrade these byproducts of DNA repair is not known. Using a small scale RNA interference screen in UV-irradiated human cells, we identified TREX1 as a major regulator of sedDNA abundance. Knockdown of TREX1 increased the level of sedDNAs containing the two major UV photoproducts and their association with the NER proteins TFIIH and RPA. Overexpression of wild-type but not nuclease-inactive TREX1 significantly diminished sedDNA levels, and studies with purified recombinant TREX1 showed that the enzyme efficiently degrades DNA located 3′ of the UV photoproduct in the sedDNA. Knockdown or overexpression of TREX1 did not impact the overall rate of UV photoproduct removal from genomic DNA or cell survival, which indicates that TREX1 function in sedDNA degradation does not impact NER efficiency. Taken together, these results indicate a previously unknown role for TREX1 in promoting the degradation of the sedDNA products of the repair reaction. Because TREX1 mutations and inefficient DNA degradation impact inflammatory and immune signaling pathways, the regulation of sedDNA degradation by TREX1 may contribute to photosensitive skin disorders.
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Affiliation(s)
- Seon Hee Kim
- Biometrology Group, Division of Chemical and Biological Metrology, Korea Research Institute of Standards and Science, Daejeon 305-340, Republic of Korea.,Department of Bio-Analytical Science, University of Science & Technology, Daejeon 305-340, Republic of Korea
| | - Geun Hoe Kim
- Biometrology Group, Division of Chemical and Biological Metrology, Korea Research Institute of Standards and Science, Daejeon 305-340, Republic of Korea.,Department of Bio-Analytical Science, University of Science & Technology, Daejeon 305-340, Republic of Korea
| | - Michael G Kemp
- Department of Pharmacology and Toxicology, Wright State University Boonshoft School of Medicine, Dayton, OH 45435, USA.,Dayton Veterans Administration Medical Center, Dayton, OH 45428, USA
| | - Jun-Hyuk Choi
- Biometrology Group, Division of Chemical and Biological Metrology, Korea Research Institute of Standards and Science, Daejeon 305-340, Republic of Korea.,Department of Bio-Analytical Science, University of Science & Technology, Daejeon 305-340, Republic of Korea
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9
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Sahay O, Barik GK, Sharma T, Pillai AD, Rapole S, Santra MK. Damsel in distress calling on her knights: Illuminating the pioneering role of E3 ubiquitin ligases in guarding the genome integrity. DNA Repair (Amst) 2021; 109:103261. [PMID: 34920250 DOI: 10.1016/j.dnarep.2021.103261] [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: 08/19/2021] [Revised: 11/30/2021] [Accepted: 12/07/2021] [Indexed: 11/03/2022]
Abstract
The maintenance of genomic integrity is of utmost importance for the organisms to survive and to accurately inherit traits to their progenies. Any kind of DNA damage either due to defect in DNA duplication and/ or uncontrolled cell division or intracellular insults or environment radiation can result in gene mutation, chromosomal aberration and ultimately genomic instability, which may cause several diseases including cancers. Therefore, cells have evolved machineries for the surveillance of genomic integrity. Enormous exciting studies in the past indicate that ubiquitination (a posttranslational modification of proteins) plays a crucial role in maintaining the genomic integrity by diverse ways. In fact, various E3 ubiquitin ligases catalyse ubiquitination of key proteins to control their central role during cell cycle, DNA damage response (DDR) and DNA repair. Some E3 ligases promote genomic instability while others prevent it, deregulation of both of which leads to several malignancies. In this review, we consolidate the recent findings wherein the role of ubiquitination in conferring genome integrity is highlighted. We also discuss the latest discoveries on the mechanisms utilized by various E3 ligases to preserve genomic stability, with a focus on their actions during cell cycle progression and different types of DNA damage response as well as repair pathways.
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Affiliation(s)
- Osheen Sahay
- National Centre for Cell Science, Ganeshkhind Road, Pune, Maharashtra 411007, India; Department of Biotechnology, S.P. Pune University, Ganeshkhind Road, Pune, Maharashtra 411007, India
| | - Ganesh Kumar Barik
- National Centre for Cell Science, Ganeshkhind Road, Pune, Maharashtra 411007, India; Department of Biotechnology, S.P. Pune University, Ganeshkhind Road, Pune, Maharashtra 411007, India
| | - Tanisha Sharma
- National Centre for Cell Science, Ganeshkhind Road, Pune, Maharashtra 411007, India; Department of Biotechnology, S.P. Pune University, Ganeshkhind Road, Pune, Maharashtra 411007, India
| | - Ajay D Pillai
- National Centre for Cell Science, Ganeshkhind Road, Pune, Maharashtra 411007, India
| | - Srikanth Rapole
- National Centre for Cell Science, Ganeshkhind Road, Pune, Maharashtra 411007, India
| | - Manas Kumar Santra
- National Centre for Cell Science, Ganeshkhind Road, Pune, Maharashtra 411007, India.
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10
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Giaccherini C, Gaillard P. Control of structure-specific endonucleases during homologous recombination in eukaryotes. Curr Opin Genet Dev 2021; 71:195-205. [PMID: 34624742 DOI: 10.1016/j.gde.2021.09.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/10/2021] [Accepted: 09/13/2021] [Indexed: 01/14/2023]
Abstract
Structure-Specific Endonucleases (SSE) are specialized DNA endonucleases that recognize and process DNA secondary structures without any strict dependency on the nucleotide sequence context. This enables them to act virtually anywhere in the genome and to make key contributions to the maintenance of genome stability by removing DNA structures that may stall essential cellular processes such as DNA replication, transcription, repair and chromosome segregation. During repair of double strand breaks by homologous recombination mechanisms, DNA secondary structures are formed and processed in a timely manner. Their homeostasis relies on the combined action of helicases, SSE and topoisomerases. In this review, we focus on how SSE contribute to DNA end resection, single-strand annealing and double-strand break repair, with an emphasis on how their action is fine-tuned in those processes.
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Affiliation(s)
- C Giaccherini
- Centre de Recherche en Cancérologie de Marseille, CRCM, Inserm, CNRS, Aix-Marseille Université, Institut Paoli-Calmettes, Marseille, France
| | - Phl Gaillard
- Centre de Recherche en Cancérologie de Marseille, CRCM, Inserm, CNRS, Aix-Marseille Université, Institut Paoli-Calmettes, Marseille, France.
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11
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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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12
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Li F, Zhou C, Tu T, Liu Y, Lv X, Wang B, Song Z, Zhao Q, Liu C, Gu F, Zhao J. Rational Selection of CRISPR-Cas Triggering Homology-Directed Repair in Human Cells. Hum Gene Ther 2021; 32:302-309. [PMID: 33323021 DOI: 10.1089/hum.2020.247] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The CRISPR (clustered regularly interspaced short palindromic repeat)-Cas (CRISPR-associated) nucleases have been widely applied for genome engineering. Cas9 (Streptococcus pyogenes Cas9 [SpCas9] and Staphylococcus aureus Cas9 [SaCas9]) and Cpf1 (i.e., Francisella novicida U112 Cpf1 [FnCpf1], also named FnCas12a) were harnessed to perform gene editing in human cells. Precise genetic modification by homology-directed repair (HDR) is an attractive approach for in situ gene correction. However, so far, the comparative efficiencies of HDR mediated by different CRISPR orthologs remain unknown. To address this question, in this study, we developed a reporter system to investigate HDR efficiencies triggered by various CRISPR orthologs. We found that SpCas9 and SaCas9, the two most commonly used Cas9 enzymes, possessed a similar ability to induce HDR. Interestingly, with the increasing amount of coding plasmids or additional nuclear localization sequences, FnCpf1 could improve the HDR efficacy. Collectively, our study provides insights for the rational selection of appropriate tools for human genome manipulation.
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Affiliation(s)
- Fanfan Li
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, State Key Laboratory and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, China.,The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Chenchen Zhou
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, State Key Laboratory and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, China
| | - Tianxiang Tu
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, State Key Laboratory and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, China
| | - Yuanyuan Liu
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, State Key Laboratory and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, China
| | - Xiujuan Lv
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, State Key Laboratory and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, China
| | - Bang Wang
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, State Key Laboratory and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, China
| | - Zongming Song
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, State Key Laboratory and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, China.,Henan Eye Hospital, Henan Provincial People's Hospital and People's Hospital of Zhengzhou University, Zhengzhou, China
| | - Qifeng Zhao
- The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Changbao Liu
- The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Feng Gu
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, State Key Laboratory and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, China
| | - Junzhao Zhao
- The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
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13
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Shen W, Ma Y, Qi H, Wang W, He J, Xiao F, Zhu H, He S. Kinetics model of DNA double-strand break repair in eukaryotes. DNA Repair (Amst) 2021; 100:103035. [PMID: 33618125 DOI: 10.1016/j.dnarep.2020.103035] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 12/11/2020] [Indexed: 11/26/2022]
Abstract
This manuscript outlines the kinetics of two main repair pathways of DNA double-strand break (DSB) in eukaryotes: non-homologous end joining (NHEJ) and homologous recombination repair (HRR). In this review, we discuss the precise study of recruitment kinetics of repair proteins based on the latest technologies in the past two decades. Then we simulate the theoretical description of the DNA repair process by mathematical models. In our study, the consecutive reactions chain (CRC) model and continuous-time random walk (CTRW) model have been unified by us, so that we can obtain the function of the number of intermediates with time in the same framework of equations, overcome the incompatibility between the two models. On this basis, we propose a data fitting workflow using these both models. Finally, we give an overview of different real-time quantitative methods and the new mechanism complexity that can be found from the corresponding dynamic models.
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Affiliation(s)
- Wangtao Shen
- Institute of Biochemistry and Molecular Biology, Hengyang Medical College, University of South China, Hengyang, 421001, China
| | - Yun Ma
- Institute of Biochemistry and Molecular Biology, Hengyang Medical College, University of South China, Hengyang, 421001, China.
| | - Huizhou Qi
- Institute of Biochemistry and Molecular Biology, Hengyang Medical College, University of South China, Hengyang, 421001, China; Function Laboratory Center, Hengyang Medical College, University of South China, Hengyang, 421001, China; Hengyang Key Laboratory for Biological Effects of Nuclear Radiation, University of South China, Hengyang, 421001, China
| | - Wuzhou Wang
- Institute of Biochemistry and Molecular Biology, Hengyang Medical College, University of South China, Hengyang, 421001, China; Hengyang Key Laboratory for Biological Effects of Nuclear Radiation, University of South China, Hengyang, 421001, China
| | - Junyan He
- Department of Radiation Oncology, The First Affiliated Hospital of University of South China, Hengyang, 421001, China
| | - Fangzhu Xiao
- Hengyang Key Laboratory for Biological Effects of Nuclear Radiation, University of South China, Hengyang, 421001, China
| | - Hui Zhu
- Institute of Engineering Mathematics, Mathematics and Physics College, University of South China, Hengyang, 421001, China
| | - Shuya He
- Institute of Biochemistry and Molecular Biology, Hengyang Medical College, University of South China, Hengyang, 421001, China; Hengyang Key Laboratory for Biological Effects of Nuclear Radiation, University of South China, Hengyang, 421001, China.
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14
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Zabolotnaya E, Mela I, Henderson RM, Robinson NP. Turning the Mre11/Rad50 DNA repair complex on its head: lessons from SMC protein hinges, dynamic coiled-coil movements and DNA loop-extrusion? Biochem Soc Trans 2020; 48:2359-2376. [PMID: 33300987 PMCID: PMC7752040 DOI: 10.1042/bst20170168] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 10/19/2020] [Accepted: 10/22/2020] [Indexed: 12/12/2022]
Abstract
The bacterial SbcC/SbcD DNA repair proteins were identified over a quarter of a century ago. Following the subsequent identification of the homologous Mre11/Rad50 complex in the eukaryotes and archaea, it has become clear that this conserved chromosomal processing machinery is central to DNA repair pathways and the maintenance of genomic stability in all forms of life. A number of experimental studies have explored this intriguing genome surveillance machinery, yielding significant insights and providing conceptual advances towards our understanding of how this complex operates to mediate DNA repair. However, the inherent complexity and dynamic nature of this chromosome-manipulating machinery continue to obfuscate experimental interrogations, and details regarding the precise mechanisms that underpin the critical repair events remain unanswered. This review will summarize our current understanding of the dramatic structural changes that occur in Mre11/Rad50 complex to mediate chromosomal tethering and accomplish the associated DNA processing events. In addition, undetermined mechanistic aspects of the DNA enzymatic pathways driven by this vital yet enigmatic chromosomal surveillance and repair apparatus will be discussed. In particular, novel and putative models of DNA damage recognition will be considered and comparisons will be made between the modes of action of the Rad50 protein and other related ATPases of the overarching SMC superfamily.
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Affiliation(s)
| | - Ioanna Mela
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, U.K
| | | | - Nicholas P. Robinson
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster LA1 4YG, U.K
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15
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McPherson MT, Holub AS, Husbands AY, Petreaca RC. Mutation Spectra of the MRN (MRE11, RAD50, NBS1/NBN) Break Sensor in Cancer Cells. Cancers (Basel) 2020; 12:cancers12123794. [PMID: 33339169 PMCID: PMC7765586 DOI: 10.3390/cancers12123794] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/04/2020] [Accepted: 12/14/2020] [Indexed: 12/12/2022] Open
Abstract
Simple Summary A DNA double strand break cuts a chromosome in two and is one of the most dangerous forms of DNA damage. Improper repair can lead to various chromosomal re-arrangements that have been detected in almost all cancer cells. A complex of three proteins (MRE11, RAD50, NBS1 or NBN) detects chromosome breaks and orchestrates repair processes. Mutations in these “break sensor” genes have been described in a multitude of cancers. Here, we provide a comprehensive analysis of reported mutations from data deposited on the Catalogue of Somatic Mutations in Cancer (COSMIC) archive. We also undertake an evolutionary analysis of these genes with the aim to understand whether these mutations preferentially accumulate in conserved residues. Interestingly, we find that mutations are overrepresented in evolutionarily conserved residues of RAD50 and NBS1/NBN but not MRE11. Abstract The MRN complex (MRE11, RAD50, NBS1/NBN) is a DNA double strand break sensor in eukaryotes. The complex directly participates in, or coordinates, several activities at the break such as DNA resection, activation of the DNA damage checkpoint, chromatin remodeling and recruitment of the repair machinery. Mutations in components of the MRN complex have been described in cancer cells for several decades. Using the Catalogue of Somatic Mutations in Cancer (COSMIC) database, we characterized all the reported MRN mutations. This analysis revealed several hotspot frameshift mutations in all three genes that introduce premature stop codons and truncate large regions of the C-termini. We also found through evolutionary analyses that COSMIC mutations are enriched in conserved residues of NBS1/NBN and RAD50 but not in MRE11. Given that all three genes are important to carcinogenesis, we propose these differential enrichment patterns may reflect a more severe pleiotropic role for MRE11.
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16
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Pasadi S, Muniyappa K. Evidence for functional and regulatory cross-talk between Wnt/β-catenin signalling and Mre11-Rad50-Nbs1 complex in the repair of cisplatin-induced DNA cross-links. Oncotarget 2020; 11:4028-4044. [PMID: 33216839 PMCID: PMC7646826 DOI: 10.18632/oncotarget.27777] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 09/10/2020] [Indexed: 12/12/2022] Open
Abstract
The canonical Wnt/β-catenin signalling pathway plays a crucial role in a variety of functions including cell proliferation and differentiation, tumorigenic processes and radioresistance in cancer cells. The Mre11–Rad50–Nbs1 (MRN) complex has a pivotal role in sensing and repairing DNA damage. However, it remains unclear whether a connection exists between Wnt/β-catenin signalling and the MRN complex in the repair of cisplatin-induced DNA interstrand cross-links (ICLs). Here, we report that (1) cisplatin exposure results in a significant increase in the levels of MRN complex subunits in human tumour cells; (2) cisplatin treatment stimulates Wnt/β-catenin signalling through increased β-catenin expression; (3) the functional perturbation of Wnt/β-catenin signalling results in aberrant cell cycle dynamics and the activation of DNA damage response and apoptosis; (4) a treatment with CHIR99021, a potent and selective GSK3β inhibitor, augments cisplatin-induced cell death in cancer cells. On the other hand, inactivation of the Wnt/β-catenin signalling with FH535 promotes cell survival. Consistently, the staining pattern of γH2AX-foci is significantly reduced in the cells exposed simultaneously to cisplatin and FH535; and (5) inhibition of Wnt/β-catenin signalling impedes cisplatin-induced phosphorylation of Chk1, abrogates the G2/M phase arrest and impairs recombination-based DNA repair. Our data further show that Wnt signalling positively regulates the expression of β-catenin, Mre11 and FANCD2 at early time points, but declining thereafter due to negative feedback regulation. These results support a model wherein Wnt/β-catenin signalling and MRN complex crosstalk during DNA ICL repair, thereby playing an important role in the maintenance of genome stability.
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Affiliation(s)
- Sanjeev Pasadi
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Kalappa Muniyappa
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
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17
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USP52 regulates DNA end resection and chemosensitivity through removing inhibitory ubiquitination from CtIP. Nat Commun 2020; 11:5362. [PMID: 33097710 PMCID: PMC7584643 DOI: 10.1038/s41467-020-19202-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 09/28/2020] [Indexed: 02/07/2023] Open
Abstract
Human C-terminal binding protein (CtBP)–interacting protein (CtIP) is a central regulator to initiate DNA end resection and homologous recombination (HR). Several studies have shown that post-translational modifications control the activity or expression of CtIP. However, it remains unclear whether and how cells restrain CtIP activity in unstressed cells and activate CtIP when needed. Here, we identify that USP52 directly interacts with and deubiquitinates CtIP, thereby promoting DNA end resection and HR. Mechanistically, USP52 removes the ubiquitination of CtIP to facilitate the phosphorylation and activation of CtIP at Thr-847. In addition, USP52 is phosphorylated by ATM at Ser-1003 after DNA damage, which enhances the catalytic activity of USP52. Furthermore, depletion of USP52 sensitizes cells to PARP inhibition in a CtIP-dependent manner in vitro and in vivo. Collectively, our findings reveal the key role of USP52 and the regulatory complexity of CtIP deubiquitination in DNA repair. C-terminal binding protein (CtBP) interacting protein (CtIP) is a fundamental factor for the initiation of DNA end resection to initiate DNA repair. Here the authors reveal mechanistic insights into the regulation of CtIP via the deubiquitinase USP52.
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18
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Rahimian E, Amini A, Alikarami F, Pezeshki SMS, Saki N, Safa M. DNA repair pathways as guardians of the genome: Therapeutic potential and possible prognostic role in hematologic neoplasms. DNA Repair (Amst) 2020; 96:102951. [PMID: 32971475 DOI: 10.1016/j.dnarep.2020.102951] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 07/30/2020] [Accepted: 08/10/2020] [Indexed: 11/30/2022]
Abstract
DNA repair pathways, which are also identified as guardians of the genome, protect cells from frequent damage that can lead to DNA breaks. The most deleterious types of damage are double-strand breaks (DSBs), which are repaired by homologous recombination (HR) and non-homologous end joining (NHEJ). Single strand breaks (SSBs) can be corrected through base excision repair (BER), nucleotide excision repair (NER), and mismatch repair (MMR). Failure to restore DNA lesions or inappropriately repaired DNA damage culminates in genomic instability and changes in the regulation of cellular functions. Intriguingly, particular mutations and translocations are accompanied by special types of leukemia. Besides, expression patterns of certain repair genes are altered in different hematologic malignancies. Moreover, analysis of mutations in key mediators of DNA damage repair (DDR) pathways, as well as investigation of their expression and function, may provide us with emerging biomarkers of response/resistance to treatment. Therefore, defective DDR pathways can offer a rational starting point for developing DNA repair-targeted drugs. In this review, we address genetic alterations and gene/protein expression changes, as well as provide an overview of DNA repair pathways.
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Affiliation(s)
- Elahe Rahimian
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Ali Amini
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Fatemeh Alikarami
- Center for Childhood Cancer Research, Children's Hospital of Philadelphia (CHOP), Philadelphia, PA 19104, USA
| | - Seyed Mohammad Sadegh Pezeshki
- Thalassemia & Hemoglobinopathy Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Najmaldin Saki
- Thalassemia & Hemoglobinopathy Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Majid Safa
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran; Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran.
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19
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Mozaffari NL, Pagliarulo F, Sartori AA. Human CtIP: A 'double agent' in DNA repair and tumorigenesis. Semin Cell Dev Biol 2020; 113:47-56. [PMID: 32950401 DOI: 10.1016/j.semcdb.2020.09.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 07/20/2020] [Accepted: 09/02/2020] [Indexed: 12/14/2022]
Abstract
Human CtIP was originally identified as an interactor of the retinoblastoma protein and BRCA1, two bona fide tumour suppressors frequently mutated in cancer. CtIP is renowned for its role in the resection of DNA double-strand breaks (DSBs) during homologous recombination, a largely error-free DNA repair pathway crucial in maintaining genome integrity. However, CtIP-dependent DNA end resection is equally accountable for alternative end-joining, a mutagenic DSB repair mechanism implicated in oncogenic chromosomal translocations. In addition, CtIP contributes to transcriptional regulation of G1/S transition, DNA damage checkpoint signalling, and replication fork protection pathways. In this review, we present a perspective on the current state of knowledge regarding the tumour-suppressive and oncogenic properties of CtIP and provide an overview of their relevance for cancer development, progression, and therapy.
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Affiliation(s)
- Nour L Mozaffari
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Fabio Pagliarulo
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Alessandro A Sartori
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland.
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20
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Abstract
Cells confront DNA damage in every cell cycle. Among the most deleterious types of DNA damage are DNA double-strand breaks (DSBs), which can cause cell lethality if unrepaired or cancers if improperly repaired. In response to DNA DSBs, cells activate a complex DNA damage checkpoint (DDC) response that arrests the cell cycle, reprograms gene expression, and mobilizes DNA repair factors to prevent the inheritance of unrepaired and broken chromosomes. Here we examine the DDC, induced by DNA DSBs, in the budding yeast model system and in mammals.
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Affiliation(s)
- David P Waterman
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454, USA;
| | - James E Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454, USA;
| | - Marcus B Smolka
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853, USA;
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21
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Tisi R, Vertemara J, Zampella G, Longhese MP. Functional and structural insights into the MRX/MRN complex, a key player in recognition and repair of DNA double-strand breaks. Comput Struct Biotechnol J 2020; 18:1137-1152. [PMID: 32489527 PMCID: PMC7260605 DOI: 10.1016/j.csbj.2020.05.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 05/07/2020] [Accepted: 05/09/2020] [Indexed: 01/20/2023] Open
Abstract
Chromosomal DNA double-strand breaks (DSBs) are potentially lethal DNA lesions that pose a significant threat to genome stability and therefore need to be repaired to preserve genome integrity. Eukaryotic cells possess two main mechanisms for repairing DSBs: non-homologous end-joining (NHEJ) and homologous recombination (HR). HR requires that the 5' terminated strands at both DNA ends are nucleolytically degraded by a concerted action of nucleases in a process termed DNA-end resection. This degradation leads to the formation of 3'-ended single-stranded DNA (ssDNA) ends that are essential to use homologous DNA sequences for repair. The evolutionarily conserved Mre11-Rad50-Xrs2/NBS1 complex (MRX/MRN) has enzymatic and structural activities to initiate DSB resection and to maintain the DSB ends tethered to each other for their repair. Furthermore, it is required to recruit and activate the protein kinase Tel1/ATM, which plays a key role in DSB signaling. All these functions depend on ATP-regulated DNA binding and nucleolytic activities of the complex. Several structures have been obtained in recent years for Mre11 and Rad50 subunits from archaea, and a few from the bacterial and eukaryotic orthologs. Nevertheless, the mechanism of activation of this protein complex is yet to be fully elucidated. In this review, we focused on recent biophysical and structural insights on the MRX complex and their interplay.
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Affiliation(s)
- Renata Tisi
- Dipartimento di Biotecnologie and Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
| | - Jacopo Vertemara
- Dipartimento di Biotecnologie and Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
| | - Giuseppe Zampella
- Dipartimento di Biotecnologie and Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie and Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
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22
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Ceppi I, Howard SM, Kasaciunaite K, Pinto C, Anand R, Seidel R, Cejka P. CtIP promotes the motor activity of DNA2 to accelerate long-range DNA end resection. Proc Natl Acad Sci U S A 2020; 117:8859-8869. [PMID: 32241893 PMCID: PMC7183222 DOI: 10.1073/pnas.2001165117] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
To repair a DNA double-strand break by homologous recombination, 5'-terminated DNA strands must first be resected to reveal 3'-overhangs. This process is initiated by a short-range resection catalyzed by MRE11-RAD50-NBS1 (MRN) stimulated by CtIP, which is followed by a long-range step involving EXO1 or DNA2 nuclease. DNA2 is a bifunctional enzyme that contains both single-stranded DNA (ssDNA)-specific nuclease and motor activities. Upon DNA unwinding by Bloom (BLM) or Werner (WRN) helicase, RPA directs the DNA2 nuclease to degrade the 5'-strand. RPA bound to ssDNA also represents a barrier, explaining the need for the motor activity of DNA2 to displace RPA prior to resection. Using ensemble and single-molecule biochemistry, we show that CtIP also dramatically stimulates the adenosine 5'-triphosphate (ATP) hydrolysis-driven motor activity of DNA2 involved in the long-range resection step. This activation in turn strongly promotes the degradation of RPA-coated ssDNA by DNA2. Accordingly, the stimulatory effect of CtIP is only observed with wild-type DNA2, but not the helicase-deficient variant. Similarly to the function of CtIP to promote MRN, also the DNA2 stimulatory effect is facilitated by CtIP phosphorylation. The domain of CtIP required to promote DNA2 is located in the central region lacking in lower eukaryotes and is fully separable from domains involved in the stimulation of MRN. These results establish how CtIP couples both MRE11-dependent short-range and DNA2-dependent long-range resection and define the involvement of the motor activity of DNA2 in this process. Our data might help explain the less severe resection defects of MRE11 nuclease-deficient cells compared to those lacking CtIP.
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Affiliation(s)
- Ilaria Ceppi
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera Italiana, Bellinzona, 6500, Switzerland
- Institute of Biochemistry, Department of Biology, ETH, Zürich, 8093, Switzerland
| | - Sean M Howard
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera Italiana, Bellinzona, 6500, Switzerland
| | - Kristina Kasaciunaite
- Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig, 04103, Germany
| | - Cosimo Pinto
- Institute of Molecular Cancer Research, University of Zürich, Zürich, 8057, Switzerland
| | - Roopesh Anand
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera Italiana, Bellinzona, 6500, Switzerland
| | - Ralf Seidel
- Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig, 04103, Germany
| | - Petr Cejka
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera Italiana, Bellinzona, 6500, Switzerland;
- Institute of Biochemistry, Department of Biology, ETH, Zürich, 8093, Switzerland
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23
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Nath S, Nagaraju G. FANCJ helicase promotes DNA end resection by facilitating CtIP recruitment to DNA double-strand breaks. PLoS Genet 2020; 16:e1008701. [PMID: 32251466 PMCID: PMC7162537 DOI: 10.1371/journal.pgen.1008701] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 04/16/2020] [Accepted: 02/28/2020] [Indexed: 12/13/2022] Open
Abstract
FANCJ helicase mutations are known to cause hereditary breast and ovarian cancers as well as bone marrow failure syndrome Fanconi anemia. FANCJ plays an important role in the repair of DNA inter-strand crosslinks and DNA double-strand breaks (DSBs) by homologous recombination (HR). Nonetheless, the molecular mechanism by which FANCJ controls HR mediated DSB repair is obscure. Here, we show that FANCJ promotes DNA end resection by recruiting CtIP to the sites of DSBs. This recruitment of CtIP is dependent on FANCJ K1249 acetylation. Notably, FANCJ acetylation is dependent on FANCJ S990 phosphorylation by CDK. The CDK mediated phosphorylation of FANCJ independently facilitates its interaction with BRCA1 at damaged DNA sites and promotes DNA end resection by CtIP recruitment. Strikingly, mutational studies reveal that ATP binding competent but hydrolysis deficient FANCJ partially supports end resection, indicating that in addition to the scaffolding role of FANCJ in CtIP recruitment, its helicase activity is important for promoting end resection. Together, these data unravel a novel function of FANCJ helicase in DNA end resection and provide mechanistic insights into its role in repairing DSBs by HR and in genome maintenance. Homologous recombination has been considered as an error-free pathway in repairing DSBs and maintaining genome stability. Cyclin-dependent kinases (CDKs) and various factors including MRE11, CtIP, EXO1, and BLM helicase participate in DNA end resection to promote HR mediated DSB repair. Despite the identification of FANCJ helicase role in HR and tumor suppression, the molecular mechanism by which FANCJ helicase participates in HR is obscure. Here, we show that FANCJ helicase controls DNA end resection by recruiting CtIP to the sites of DSBs. The loading of CtIP is dependent on FANCJ acetylation which is mediated by CDK dependent phosphorylation of FANCJ. Moreover, in addition to FANCJ mediated CtIP recruitment, its helicase activity is also essential for DNA end resection. Our data identify FANCJ as a novel player in the DNA end resection and provide insights into its role in HR mediated DSB repair.
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Affiliation(s)
- Sarmi Nath
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Ganesh Nagaraju
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
- * E-mail:
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24
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Stroik S, Kurtz K, Hendrickson EA. CtIP is essential for telomere replication. Nucleic Acids Res 2019; 47:8927-8940. [PMID: 31378812 PMCID: PMC6755089 DOI: 10.1093/nar/gkz652] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 07/08/2019] [Accepted: 07/16/2019] [Indexed: 01/10/2023] Open
Abstract
The maintenance of telomere length is critical to longevity and survival. Specifically, the failure to properly replicate, resect, and/or form appropriate telomeric structures drives telomere shortening and, in turn, genomic instability. The endonuclease CtIP is a DNA repair protein that is well-known to promote genome stability through the resection of endogenous DNA double-stranded breaks. Here, we describe a novel role for CtIP. We show that in the absence of CtIP, human telomeres shorten rapidly to non-viable lengths. This telomere dysfunction results in an accumulation of fusions, breaks, and frank telomere loss. Additionally, CtIP suppresses the generation of circular, extrachromosomal telomeric DNA. These latter structures appear to arise from arrested DNA replication forks that accumulate in the absence of CtIP. Hence, CtIP is required for faithful replication through telomeres via its roles at stalled replication tracts. Our findings demonstrate a new role for CtIP as a protector of human telomere integrity.
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Affiliation(s)
- Susanna Stroik
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Kevin Kurtz
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
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25
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Trenner A, Sartori AA. Harnessing DNA Double-Strand Break Repair for Cancer Treatment. Front Oncol 2019; 9:1388. [PMID: 31921645 PMCID: PMC6921965 DOI: 10.3389/fonc.2019.01388] [Citation(s) in RCA: 129] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 11/25/2019] [Indexed: 12/20/2022] Open
Abstract
DNA double-strand breaks (DSBs) are highly deleterious, with a single unrepaired DSB being sufficient to trigger cell death. Compared to healthy cells, cancer cells have a higher DSB burden due to oncogene-induced replication stress and acquired defects in DNA damage response (DDR) mechanisms. Consequently, hyperproliferating cancer cells rely on efficient DSB repair for their survival. Moreover, augmented DSB repair capacity is a major cause of radio- and chemoresistance and, ultimately, cancer recurrence. Although inherited DDR defects can predispose individuals to develop certain cancers, the very same vulnerability may be therapeutically exploited to preferentially kill tumor cells. A paradigm for DNA repair targeted therapy has emerged in cancers that exhibit mutations in BRCA1 or BRCA2 tumor suppressor genes, conferring a strong defect in homologous recombination, a major and error-free DSB repair pathway. Clinical validation of such approaches, commonly described as synthetic lethality (SL), has been provided by the regulatory approval of poly(ADP-ribose) polymerase 1 inhibitors (PARPi) as monotherapy for BRCA1/2-mutated breast and ovarian tumors. In this review, we will describe the different DSB repair mechanisms and discuss how their specific features could be exploited for cancer therapy. A major emphasis is put on advances in combinatorial treatment modalities and SL approaches arising from DSB repair pathway interdependencies.
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Affiliation(s)
- Anika Trenner
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Alessandro A Sartori
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
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26
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Hamilton NA, Wendel BM, Weber EA, Courcelle CT, Courcelle J. RecBCD, SbcCD and ExoI process a substrate created by convergent replisomes to complete DNA replication. Mol Microbiol 2019; 111:1638-1651. [PMID: 30883946 DOI: 10.1111/mmi.14242] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/12/2019] [Indexed: 12/11/2022]
Abstract
The accurate completion of DNA replication on the chromosome requires RecBCD and structure specific SbcCD and ExoI nucleases. However, the substrates and mechanism by which this reaction occurs remains unknown. Here we show that these completion enzymes operate on plasmid substrates containing two replisomes, but are not required for plasmids containing one replisome. Completion on the two-replisome plasmids requires RecBCD, but does not require RecA and no broken intermediates accumulate in its absence, indicating that the completion reaction occurs normally in the absence of any double-strand breaks. Further, similar to the chromosome, we show that when the normal completion reaction is prevented, an aberrant RecA-mediated recombination process leads to amplifications that drive most of the instabilities associated with the two-replisome substrates. The observations imply that the substrate SbcCD, ExoI and RecBCD act upon in vivo is created specifically by two convergent replisomes, and demonstrate that the function of RecBCD in completing replication is independent of double-strand break repair, and likely promotes joining of the strands of the convergent replication forks.
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Affiliation(s)
- Nicklas A Hamilton
- Department of Biology, Portland State University, Portland, OR, 97201, USA
| | - Brian M Wendel
- Department of Biology, Portland State University, Portland, OR, 97201, USA
| | - Emma A Weber
- Department of Biology, Portland State University, Portland, OR, 97201, USA
| | | | - Justin Courcelle
- Department of Biology, Portland State University, Portland, OR, 97201, USA
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27
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Godau J, Ferretti LP, Trenner A, Dubois E, von Aesch C, Marmignon A, Simon L, Kapusta A, Guérois R, Bétermier M, Sartori AA. Identification of a miniature Sae2/Ctp1/CtIP ortholog from Paramecium tetraurelia required for sexual reproduction and DNA double-strand break repair. DNA Repair (Amst) 2019; 77:96-108. [DOI: 10.1016/j.dnarep.2019.03.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 01/28/2019] [Accepted: 03/21/2019] [Indexed: 12/24/2022]
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Murai J, Pommier Y. PARP Trapping Beyond Homologous Recombination and Platinum Sensitivity in Cancers. ANNUAL REVIEW OF CANCER BIOLOGY-SERIES 2019. [DOI: 10.1146/annurev-cancerbio-030518-055914] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Poly(ADP-ribose) polymerase inhibitors (PARPis) have recently been approved for the treatment of ovarian and breast cancers with BRCA mutations, as well as for maintenance therapies regardless of BRCA mutation for ovarian and primary peritoneal cancers that previously responded to platinum-based chemotherapy. The rationale of these indications is derived from the facts that cancer cells with BRCA mutations are defective in homologous recombination (HR), which confers synthetic lethality with PARPis, and that some of the sensitivity-determining factors for PARPis are shared with platinums. Although BRCA1 and BRCA2 are central for HR, more players within and beyond HR are emerging as response determinants to PARPis. Furthermore, there are similarities as well as differences in the DNA lesions and repair pathways induced by PARPis, platinums, and camptothecin topoisomerase 1 (TOP1) inhibitors. Here we review the sensitivity-determining factors for PARPis and the rationale for using PARPis as single agents and in combination therapy for cancers.
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Affiliation(s)
- Junko Murai
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA;,
| | - Yves Pommier
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA;,
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29
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Kim Y, Furman CM, Manhart CM, Alani E, Finkelstein I. Intrinsically disordered regions regulate both catalytic and non-catalytic activities of the MutLα mismatch repair complex. Nucleic Acids Res 2019; 47:1823-1835. [PMID: 30541127 PMCID: PMC6393296 DOI: 10.1093/nar/gky1244] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 11/27/2018] [Accepted: 12/05/2018] [Indexed: 12/12/2022] Open
Abstract
Intrinsically disordered regions (IDRs) are present in at least 30% of the eukaryotic proteome and are enriched in chromatin-associated proteins. Using a combination of genetics, biochemistry and single-molecule biophysics, we characterize how IDRs regulate the functions of the yeast MutLα (Mlh1-Pms1) mismatch repair (MMR) complex. Shortening or scrambling the IDRs in both subunits ablates MMR in vivo. Mlh1-Pms1 complexes with shorter IDRs that disrupt MMR retain wild-type DNA binding affinity but are impaired for diffusion on both naked and nucleosome-coated DNA. Moreover, the IDRs also regulate the adenosine triphosphate hydrolysis and nuclease activities that are encoded in the structured N- and C-terminal domains of the complex. This combination of phenotypes underlies the catastrophic MMR defect seen with the mutant MutLα in vivo. More broadly, this work highlights an unanticipated multi-functional role for IDRs in regulating both facilitated diffusion on chromatin and nucleolytic processing of a DNA substrate.
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Affiliation(s)
- Yoori Kim
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Christopher M Furman
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Carol M Manhart
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Eric Alani
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Ilya J Finkelstein
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA
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Bordelet H, Dubrana K. Keep moving and stay in a good shape to find your homologous recombination partner. Curr Genet 2019; 65:29-39. [PMID: 30097675 PMCID: PMC6342867 DOI: 10.1007/s00294-018-0873-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Revised: 07/31/2018] [Accepted: 08/02/2018] [Indexed: 01/02/2023]
Abstract
Genomic DNA is constantly exposed to damage. Among the lesion in DNA, double-strand breaks (DSB), because they disrupt the two strands of the DNA double helix, are the more dangerous. DSB are repaired through two evolutionary conserved mechanisms: Non-Homologous End Joining (NHEJ) and Homologous Recombination (HR). Whereas NHEJ simply reseals the double helix with no or minimal processing, HR necessitates the formation of a 3'ssDNA through the processing of DSB ends by the resection machinery and relies on the recognition and pairing of this 3'ssDNA tails with an intact homologous sequence. Despite years of active research on HR, the manner by which the two homologous sequences find each other in the crowded nucleus, and how this modulates HR efficiency, only recently emerges. Here, we review recent advances in our understanding of the factors limiting the search of a homologous sequence during HR.
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Affiliation(s)
- Hélène Bordelet
- Laboratoire Instabilité et Organisation Nucléaire, iRCM, IBFJ, DRF, CEA. 2 INSERM, U967. 3 Université Paris Diderot et Paris Saclay, UMR967, Fontenay-aux-roses, 92265, France
| | - Karine Dubrana
- Laboratoire Instabilité et Organisation Nucléaire, iRCM, IBFJ, DRF, CEA. 2 INSERM, U967. 3 Université Paris Diderot et Paris Saclay, UMR967, Fontenay-aux-roses, 92265, France.
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31
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Andres SN, Li ZM, Erie DA, Williams RS. Ctp1 protein-DNA filaments promote DNA bridging and DNA double-strand break repair. J Biol Chem 2019; 294:3312-3320. [PMID: 30626735 DOI: 10.1074/jbc.ra118.006759] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 12/26/2018] [Indexed: 12/13/2022] Open
Abstract
The Ctp1 protein in Schizosaccharomyces pombe is essential for DNA double-strand break (DSB) repair by homologous recombination. Fission yeast Ctp1 and its budding yeast (Sae2) and human (CtIP) homologs control Mre11-Rad50-Nbs1 nuclease complex activity and harbor DNA-binding and -bridging activities. However, the molecular basis for Ctp1-DNA transactions remains undefined. Here, we report atomic force microscopy (AFM) imaging of S. pombe Ctp1-DNA complexes revealing that Ctp1 polymerizes on dsDNA molecules and forms synaptic filaments that bridge two dsDNA strands. We observed that Ctp1 DNA filaments are typified by an average filament length of ∼180 bp of dsDNA and a Ctp1 tetramer footprint of ∼15 bp. Biochemical results characterizing Ctp1 variants with impaired DNA-binding or -bridging properties were consistent with Ctp1-mediated DNA bridging requiring the intact and correctly folded Ctp1 tetramer. Furthermore, mutations altering Ctp1 oligomerization and DNA bridging in vitro conferred cell sensitivity to DSB-producing agents. Together, these results support an important role for Ctp1-regulated DNA strand coordination required for DNA DSB repair in S. pombe.
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Affiliation(s)
- Sara N Andres
- From the Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina 27709
| | - Zimeng M Li
- the Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27695, and
| | - Dorothy A Erie
- the Department of Chemistry, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599
| | - R Scott Williams
- From the Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina 27709,
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32
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Klein HL, Bačinskaja G, Che J, Cheblal A, Elango R, Epshtein A, Fitzgerald DM, Gómez-González B, Khan SR, Kumar S, Leland BA, Marie L, Mei Q, Miné-Hattab J, Piotrowska A, Polleys EJ, Putnam CD, Radchenko EA, Saada AA, Sakofsky CJ, Shim EY, Stracy M, Xia J, Yan Z, Yin Y, Aguilera A, Argueso JL, Freudenreich CH, Gasser SM, Gordenin DA, Haber JE, Ira G, Jinks-Robertson S, King MC, Kolodner RD, Kuzminov A, Lambert SAE, Lee SE, Miller KM, Mirkin SM, Petes TD, Rosenberg SM, Rothstein R, Symington LS, Zawadzki P, Kim N, Lisby M, Malkova A. Guidelines for DNA recombination and repair studies: Cellular assays of DNA repair pathways. MICROBIAL CELL (GRAZ, AUSTRIA) 2019; 6:1-64. [PMID: 30652105 PMCID: PMC6334234 DOI: 10.15698/mic2019.01.664] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Revised: 08/29/2018] [Accepted: 09/14/2018] [Indexed: 12/29/2022]
Abstract
Understanding the plasticity of genomes has been greatly aided by assays for recombination, repair and mutagenesis. These assays have been developed in microbial systems that provide the advantages of genetic and molecular reporters that can readily be manipulated. Cellular assays comprise genetic, molecular, and cytological reporters. The assays are powerful tools but each comes with its particular advantages and limitations. Here the most commonly used assays are reviewed, discussed, and presented as the guidelines for future studies.
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Affiliation(s)
- Hannah L. Klein
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Giedrė Bačinskaja
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Jun Che
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, USA
| | - Anais Cheblal
- Friedrich Miescher Institute for Biomedical Research (FMI), 4058 Basel, Switzerland
| | - Rajula Elango
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | - Anastasiya Epshtein
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Devon M. Fitzgerald
- Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Belén Gómez-González
- Centro Andaluz de BIología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla, Seville, Spain
| | - Sharik R. Khan
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Sandeep Kumar
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | | | - Léa Marie
- Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY, USA
| | - Qian Mei
- Systems, Synthetic and Physical Biology Graduate Program, Rice University, Houston, TX, USA
| | - Judith Miné-Hattab
- Institut Curie, PSL Research University, CNRS, UMR3664, F-75005 Paris, France
- Sorbonne Université, Institut Curie, CNRS, UMR3664, F-75005 Paris, France
| | - Alicja Piotrowska
- NanoBioMedical Centre, Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan, Poland
| | | | - Christopher D. Putnam
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, CA, USA
- Department of Medicine, University of California School of Medicine, San Diego, La Jolla, CA, USA
| | | | - Anissia Ait Saada
- Institut Curie, PSL Research University, CNRS, UMR3348 F-91405, Orsay, France
- University Paris Sud, Paris-Saclay University, CNRS, UMR3348, F-91405, Orsay, France
| | - Cynthia J. Sakofsky
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, Durham, NC, USA
| | - Eun Yong Shim
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, USA
| | - Mathew Stracy
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Jun Xia
- Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Zhenxin Yan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Yi Yin
- Department of Molecular Genetics and Microbiology and University Program in Genetics and Genomics, Duke University Medical Center, Durham, NC USA
| | - Andrés Aguilera
- Centro Andaluz de BIología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla, Seville, Spain
| | - Juan Lucas Argueso
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
| | - Catherine H. Freudenreich
- Department of Biology, Tufts University, Medford, MA USA
- Program in Genetics, Tufts University, Boston, MA, USA
| | - Susan M. Gasser
- Friedrich Miescher Institute for Biomedical Research (FMI), 4058 Basel, Switzerland
| | - Dmitry A. Gordenin
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, Durham, NC, USA
| | - James E. Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center Brandeis University, Waltham, MA, USA
| | - Grzegorz Ira
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Sue Jinks-Robertson
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC USA
| | | | - Richard D. Kolodner
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, CA, USA
- Department of Cellular and Molecular Medicine, University of California School of Medicine, San Diego, La Jolla, CA, USA
- Moores-UCSD Cancer Center, University of California School of Medicine, San Diego, La Jolla, CA, USA
- Institute of Genomic Medicine, University of California School of Medicine, San Diego, La Jolla, CA, USA
| | - Andrei Kuzminov
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Sarah AE Lambert
- Institut Curie, PSL Research University, CNRS, UMR3348 F-91405, Orsay, France
- University Paris Sud, Paris-Saclay University, CNRS, UMR3348, F-91405, Orsay, France
| | - Sang Eun Lee
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, USA
| | - Kyle M. Miller
- Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | | | - Thomas D. Petes
- Department of Molecular Genetics and Microbiology and University Program in Genetics and Genomics, Duke University Medical Center, Durham, NC USA
| | - Susan M. Rosenberg
- Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
- Systems, Synthetic and Physical Biology Graduate Program, Rice University, Houston, TX, USA
| | - Rodney Rothstein
- Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY, USA
| | - Lorraine S. Symington
- Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY, USA
| | - Pawel Zawadzki
- NanoBioMedical Centre, Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan, Poland
| | - Nayun Kim
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Michael Lisby
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Anna Malkova
- Department of Biology, University of Iowa, Iowa City, IA, USA
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Wilkinson OJ, Martín-González A, Kang H, Northall SJ, Wigley DB, Moreno-Herrero F, Dillingham MS. CtIP forms a tetrameric dumbbell-shaped particle which bridges complex DNA end structures for double-strand break repair. eLife 2019; 8:42129. [PMID: 30601117 PMCID: PMC6344080 DOI: 10.7554/elife.42129] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 01/01/2019] [Indexed: 12/16/2022] Open
Abstract
CtIP is involved in the resection of broken DNA during the S and G2 phases of the cell cycle for repair by recombination. Acting with the MRN complex, it plays a particularly important role in handling complex DNA end structures by localised nucleolytic processing of DNA termini in preparation for longer range resection. Here we show that human CtIP is a tetrameric protein adopting a dumbbell architecture in which DNA binding domains are connected by long coiled-coils. The protein complex binds two short DNA duplexes with high affinity and bridges DNA molecules in trans. DNA binding is potentiated by dephosphorylation and is not specific for DNA end structures per se. However, the affinity for linear DNA molecules is increased if the DNA terminates with complex structures including forked ssDNA overhangs and nucleoprotein conjugates. This work provides a biochemical and structural basis for the function of CtIP at complex DNA breaks.
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Affiliation(s)
| | - Alejandro Martín-González
- Department of Macromolecular Structures, Centro Nacional de Biotecnologia, Consejo Superior de Investigaciones Cientificas, Madrid, Spain
| | - Haejoo Kang
- Department of Medicine, Imperial College London, London, United Kingdom
| | - Sarah J Northall
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Dale B Wigley
- Department of Medicine, Imperial College London, London, United Kingdom
| | - Fernando Moreno-Herrero
- Department of Macromolecular Structures, Centro Nacional de Biotecnologia, Consejo Superior de Investigaciones Cientificas, Madrid, Spain
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Oh J, Symington LS. Role of the Mre11 Complex in Preserving Genome Integrity. Genes (Basel) 2018; 9:E589. [PMID: 30501098 PMCID: PMC6315862 DOI: 10.3390/genes9120589] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 11/26/2018] [Accepted: 11/27/2018] [Indexed: 12/12/2022] Open
Abstract
DNA double-strand breaks (DSBs) are hazardous lesions that threaten genome integrity and cell survival. The DNA damage response (DDR) safeguards the genome by sensing DSBs, halting cell cycle progression and promoting repair through either non-homologous end joining (NHEJ) or homologous recombination (HR). The Mre11-Rad50-Xrs2/Nbs1 (MRX/N) complex is central to the DDR through its structural, enzymatic, and signaling roles. The complex tethers DNA ends, activates the Tel1/ATM kinase, resolves protein-bound or hairpin-capped DNA ends, and maintains telomere homeostasis. In addition to its role at DSBs, MRX/N associates with unperturbed replication forks, as well as stalled replication forks, to ensure complete DNA synthesis and to prevent chromosome rearrangements. Here, we summarize the significant progress made in characterizing the MRX/N complex and its various activities in chromosome metabolism.
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Affiliation(s)
- Julyun Oh
- Biological Sciences Program, Columbia University, New York, NY 10027, USA.
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.
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35
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CtIP-Mediated Fork Protection Synergizes with BRCA1 to Suppress Genomic Instability upon DNA Replication Stress. Mol Cell 2018; 72:568-582.e6. [DOI: 10.1016/j.molcel.2018.09.014] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 06/08/2018] [Accepted: 09/12/2018] [Indexed: 12/30/2022]
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36
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Shou J, Li J, Liu Y, Wu Q. Precise and Predictable CRISPR Chromosomal Rearrangements Reveal Principles of Cas9-Mediated Nucleotide Insertion. Mol Cell 2018; 71:498-509.e4. [PMID: 30033371 DOI: 10.1016/j.molcel.2018.06.021] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 04/22/2018] [Accepted: 06/13/2018] [Indexed: 01/21/2023]
Abstract
Chromosomal rearrangements including large DNA-fragment inversions, deletions, and duplications by Cas9 with paired sgRNAs are important to investigate genome structural variations and developmental gene regulation, but little is known about the underlying mechanisms. Here, we report that disrupting CtIP or FANCD2, which have roles in alternative non-homologous end joining, enhances precise DNA-fragment deletion. By analyzing the inserted nucleotides at the junctions of DNA-fragment editing of deletions, inversions, and duplications and characterizing the cleaved products, we find that Cas9 endonucleolytically cleaves the noncomplementary strand with a flexible scissile profile upstream of the -3 position of the PAM site in vivo and in vitro, generating double-strand break ends with 5' overhangs of 1-3 nucleotides. Moreover, we find that engineered Cas9 nucleases have distinct cleavage profiles. Finally, Cas9-mediated nucleotide insertions are nonrandom and are equal to the combined sequences upstream of both PAM sites with predicted frequencies. Thus, precise and predictable DNA-fragment editing could be achieved by perturbing DNA repair genes and using appropriate PAM configurations.
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Affiliation(s)
- Jia Shou
- Key Lab of Systems Biomedicine (Ministry of Education), Center for Comparative Biomedicine, Institute of Systems Biomedicine, SCSB, Shanghai Jiao Tong University (SJTU), Shanghai 200240, China; State Key Lab of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, SJTU Medical School, Shanghai 200240, China; Shanghai Key Lab of Biliary Tract Research, Xinhua Hospital, SJTU Medical School, Shanghai 200240, China
| | - Jinhuan Li
- Key Lab of Systems Biomedicine (Ministry of Education), Center for Comparative Biomedicine, Institute of Systems Biomedicine, SCSB, Shanghai Jiao Tong University (SJTU), Shanghai 200240, China; State Key Lab of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, SJTU Medical School, Shanghai 200240, China; Shanghai Key Lab of Biliary Tract Research, Xinhua Hospital, SJTU Medical School, Shanghai 200240, China
| | - Yingbin Liu
- Shanghai Key Lab of Biliary Tract Research, Xinhua Hospital, SJTU Medical School, Shanghai 200240, China
| | - Qiang Wu
- Key Lab of Systems Biomedicine (Ministry of Education), Center for Comparative Biomedicine, Institute of Systems Biomedicine, SCSB, Shanghai Jiao Tong University (SJTU), Shanghai 200240, China; State Key Lab of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, SJTU Medical School, Shanghai 200240, China; Shanghai Key Lab of Biliary Tract Research, Xinhua Hospital, SJTU Medical School, Shanghai 200240, China.
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Mre11 complex links sister chromatids to promote repair of a collapsed replication fork. Proc Natl Acad Sci U S A 2018; 115:8793-8798. [PMID: 30104346 DOI: 10.1073/pnas.1808189115] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Collapsed replication forks, which are a major source of DNA double-strand breaks (DSBs), are repaired by sister chromatid recombination (SCR). The Mre11-Rad50-Nbs1 (MRN) protein complex, assisted by CtIP/Sae2/Ctp1, initiates SCR by nucleolytically resecting the single-ended DSB (seDSB) at the collapsed fork. The molecular architecture of the MRN intercomplex, in which zinc hooks at the apices of long Rad50 coiled-coils connect two Mre112-Rad502 complexes, suggests that MRN also structurally assists SCR. Here, Rad50 ChIP assays in Schizosaccharomyces pombe show that MRN sequentially localizes with the seDSB and sister chromatid at a collapsed replication fork. Ctp1, which has multivalent DNA-binding and DNA-bridging activities, has the same DNA interaction pattern. Provision of an intrachromosomal repair template alleviates the nonnucleolytic requirement for MRN to repair the broken fork. Mutations of zinc-coordinating cysteines in the Rad50 hook severely impair SCR. These data suggest that the MRN complex facilitates SCR by linking the seDSB and sister chromatid.
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Khan RI, Nirzhor SSR, Akter R. A Review of the Recent Advances Made with SIRT6 and its Implications on Aging Related Processes, Major Human Diseases, and Possible Therapeutic Targets. Biomolecules 2018; 8:biom8030044. [PMID: 29966233 PMCID: PMC6164879 DOI: 10.3390/biom8030044] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 06/24/2018] [Accepted: 06/26/2018] [Indexed: 12/20/2022] Open
Abstract
Sirtuin 6 (SIRT6) is a nicotinamide adenine dinucleotide+ (NAD+) dependent enzyme and stress response protein that has sparked the curiosity of many researchers in different branches of the biomedical sciences. A unique member of the known Sirtuin family, SIRT6 has several different functions in multiple different molecular pathways related to DNA repair, glycolysis, gluconeogenesis, tumorigenesis, neurodegeneration, cardiac hypertrophic responses, and more. Only in recent times, however, did the potential usefulness of SIRT6 come to light as we learned more about its biochemical activity, regulation, biological roles, and structure Frye (2000). Even until very recently, SIRT6 was known more for chromatin signaling but, being a nascent topic of study, more information has been ascertained and its potential involvement in major human diseases including diabetes, cancer, neurodegenerative diseases, and heart disease. It is pivotal to explore the mechanistic workings of SIRT6 since future research may hold the key to engendering strategies involving SIRT6 that may have significant implications for human health and expand upon possible treatment options. In this review, we are primarily concerned with exploring the latest advances in understanding SIRT6 and how it can alter the course of several life-threatening diseases such as processes related to aging, cancer, neurodegenerative diseases, heart disease, and diabetes (SIRT6 has also shown to be involved in liver disease, inflammation, and bone-related issues) and any recent promising pharmacological investigations or potential therapeutics that are of interest.
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Affiliation(s)
| | | | - Raushanara Akter
- Department of Pharmacy, BRAC University, 1212 Dhaka, Bangladesh.
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Syed A, Tainer JA. The MRE11-RAD50-NBS1 Complex Conducts the Orchestration of Damage Signaling and Outcomes to Stress in DNA Replication and Repair. Annu Rev Biochem 2018; 87:263-294. [PMID: 29709199 PMCID: PMC6076887 DOI: 10.1146/annurev-biochem-062917-012415] [Citation(s) in RCA: 255] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Genomic instability in disease and its fidelity in health depend on the DNA damage response (DDR), regulated in part from the complex of meiotic recombination 11 homolog 1 (MRE11), ATP-binding cassette-ATPase (RAD50), and phosphopeptide-binding Nijmegen breakage syndrome protein 1 (NBS1). The MRE11-RAD50-NBS1 (MRN) complex forms a multifunctional DDR machine. Within its network assemblies, MRN is the core conductor for the initial and sustained responses to DNA double-strand breaks, stalled replication forks, dysfunctional telomeres, and viral DNA infection. MRN can interfere with cancer therapy and is an attractive target for precision medicine. Its conformations change the paradigm whereby kinases initiate damage sensing. Delineated results reveal kinase activation, posttranslational targeting, functional scaffolding, conformations storing binding energy and enabling access, interactions with hub proteins such as replication protein A (RPA), and distinct networks at DNA breaks and forks. MRN biochemistry provides prototypic insights into how it initiates, implements, and regulates multifunctional responses to genomic stress.
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Affiliation(s)
- Aleem Syed
- Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA; ,
| | - John A Tainer
- Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA; ,
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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Wang Y, Jiang L, Zhang T, Jing J, He Y. ZmCom1 Is Required for Both Mitotic and Meiotic Recombination in Maize. FRONTIERS IN PLANT SCIENCE 2018; 9:1005. [PMID: 30061907 PMCID: PMC6055016 DOI: 10.3389/fpls.2018.01005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 06/20/2018] [Indexed: 05/02/2023]
Abstract
CtIP/Ctp1/Sae2/Com1, a highly conserved protein from yeast to higher eukaryotes, is required for DNA double-strand break repair through homologous recombination (HR). In this study, we identified and characterized the COM1 homolog in maize. The ZmCom1 gene is abundantly expressed in reproductive tissues at meiosis stages. In ZmCom1-deficient plants, meiotic chromosomes are constantly entangled as a formation of multivalents and accompanied with chromosome fragmentation at anaphase I. In addition, the formation of telomere bouquet, homologous pairing and synapsis were disturbed. The immunostaining assay showed that the localization of ASY1 and DSY2 was normal, while ZYP1 signals were severely disrupted in Zmcom1 meiocytes, indicating that ZmCom1 is critically required for the proper SC assembly. Moreover, RAD51 signals were almost completely absent in Zmcom1 meiocytes, implying that COM1 is required for RAD51 loading. Surprisingly, in contrast to the Atcom1 and Oscom1 mutants, Zmcom1 mutant plants exhibited a number of vegetative phenotypes under normal growth condition, which may be partly attributed to mitotic aberrations including chromosomal fragmentation and anaphase bridges. Taken together, our results suggest that although the roles of COM1 in HR process seem to be primarily conserved, the COM1 dysfunction can result in the marked dissimilarity in mitotic and meiotic outcomes in maize compared to Arabidopsis and rice. We suggest that this character may be related to the discrete genome context.
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SAMHD1 Sheds Moonlight on DNA Double-Strand Break Repair. Trends Genet 2017; 33:895-897. [PMID: 28969870 DOI: 10.1016/j.tig.2017.09.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 09/19/2017] [Indexed: 12/31/2022]
Abstract
SAMHD1 (sterile α motif and histidine (H) aspartate (D) domain-containing protein 1) is known for its antiviral activity of hydrolysing deoxynucleotides required for virus replication. Daddacha et al. identify a hydrolase-independent, moonlighting function of SAMHD1 that facilitates homologous recombination of DNA double-strand breaks (DSBs) by promoting recruitment of C-terminal binding protein interacting protein (CTIP), a DNA-end resection factor, to damaged DNA. These findings could benefit anticancer treatment.
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