51
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Subramanyam S, Spies M. RAD51 discrimination between single- and double-strand DNA: a matter of flexibility and enthalpy. EMBO J 2020; 39:e104547. [PMID: 32090346 PMCID: PMC7110141 DOI: 10.15252/embj.2020104547] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2024] Open
Abstract
In selecting ssDNA over dsDNA, the RAD51 DNA strand exchange protein has to overcome the entropy associated with straightening of single-strand DNA upon nucleoprotein filament formation. New work in The EMBO Journal (Paoletti et al, 2020), combined biophysical analysis of the RAD51-ssDNA interaction with mathematical modeling to show that the flexibility of DNA positively correlates with nucleation and extension of the RAD51 nucleoprotein filament and that the entropic penalty associated with restricting ssDNA flexibility is offset by a strong RAD51-RAD51 interaction within the nucleoprotein filament.
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Affiliation(s)
- Shyamal Subramanyam
- Department of Radiation OncologyMemorial Sloan Kettering Cancer CenterNew YorkNYUSA
| | - Maria Spies
- Department of BiochemistryCarver College of MedicineUniversity of IowaIowa CityIAUSA
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52
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Li Y, McGrail DJ, Latysheva N, Yi S, Babu MM, Sahni N. Pathway perturbations in signaling networks: Linking genotype to phenotype. Semin Cell Dev Biol 2020; 99:3-11. [PMID: 29738884 PMCID: PMC6230320 DOI: 10.1016/j.semcdb.2018.05.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 03/29/2018] [Accepted: 05/04/2018] [Indexed: 02/07/2023]
Abstract
Genes and gene products interact with each other to form signal transduction networks in the cell. The interactome networks are under intricate regulation in physiological conditions, but could go awry upon genome instability caused by genetic mutations. In the past decade with next-generation sequencing technologies, an increasing number of genomic mutations have been identified in a variety of disease patients and healthy individuals. As functional and systematic studies on these mutations leap forward, they begin to reveal insights into cellular homeostasis and disease mechanisms. In this review, we discuss recent advances in the field of network biology and signaling pathway perturbations upon genomic changes, and highlight the success of various omics datasets in unraveling genotype-to-phenotype relationships.
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Affiliation(s)
- Yongsheng Li
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Daniel J McGrail
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Natasha Latysheva
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Song Yi
- Department of Oncology, Dell Medical School, The University of Texas at Austin, Austin, TX, 78712, USA.
| | - M Madan Babu
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
| | - Nidhi Sahni
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA; Program in Quantitative and Computational Biosciences, Baylor College of Medicine, Houston, TX, 77030, USA; Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.
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53
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Yu J, Qin B, Lou Z. Ubiquitin and ubiquitin-like molecules in DNA double strand break repair. Cell Biosci 2020; 10:13. [PMID: 32071713 PMCID: PMC7014694 DOI: 10.1186/s13578-020-0380-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 01/30/2020] [Indexed: 12/23/2022] Open
Abstract
Both environmental and endogenous factors induce various forms of DNA damage. DNA double strand break (DSB) is the most deleterious DNA lesion. The swift initiation of a complexed network of interconnected pathways to repair the DNA lesion is essential for cell survival. In the past years, the roles of ubiquitin and ubiquitin-like proteins in DNA damage response and DNA repair has been explored. These findings help us better understand the complicated mechanism of DSB signaling pathways.
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Affiliation(s)
- Jia Yu
- 1Division of Clinical Pharmacology, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905 USA
| | - Bo Qin
- 1Division of Clinical Pharmacology, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905 USA.,2Department of Oncology, Mayo Clinic, Rochester, MN 55905 USA.,3Gastrointestinal Research Unit, Mayo Clinic, Rochester, MN 55905 USA
| | - Zhenkun Lou
- 2Department of Oncology, Mayo Clinic, Rochester, MN 55905 USA
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54
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Sun Y, McCorvie TJ, Yates LA, Zhang X. Structural basis of homologous recombination. Cell Mol Life Sci 2020; 77:3-18. [PMID: 31748913 PMCID: PMC6957567 DOI: 10.1007/s00018-019-03365-1] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 10/10/2019] [Accepted: 10/31/2019] [Indexed: 12/12/2022]
Abstract
Homologous recombination (HR) is a pathway to faithfully repair DNA double-strand breaks (DSBs). At the core of this pathway is a DNA recombinase, which, as a nucleoprotein filament on ssDNA, pairs with homologous DNA as a template to repair the damaged site. In eukaryotes Rad51 is the recombinase capable of carrying out essential steps including strand invasion, homology search on the sister chromatid and strand exchange. Importantly, a tightly regulated process involving many protein factors has evolved to ensure proper localisation of this DNA repair machinery and its correct timing within the cell cycle. Dysregulation of any of the proteins involved can result in unchecked DNA damage, leading to uncontrolled cell division and cancer. Indeed, many are tumour suppressors and are key targets in the development of new cancer therapies. Over the past 40 years, our structural and mechanistic understanding of homologous recombination has steadily increased with notable recent advancements due to the advances in single particle cryo electron microscopy. These have resulted in higher resolution structural models of the signalling proteins ATM (ataxia telangiectasia mutated), and ATR (ataxia telangiectasia and Rad3-related protein), along with various structures of Rad51. However, structural information of the other major players involved, such as BRCA1 (breast cancer type 1 susceptibility protein) and BRCA2 (breast cancer type 2 susceptibility protein), has been limited to crystal structures of isolated domains and low-resolution electron microscopy reconstructions of the full-length proteins. Here we summarise the current structural understanding of homologous recombination, focusing on key proteins in recruitment and signalling events as well as the mediators for the Rad51 recombinase.
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Affiliation(s)
- Yueru Sun
- Section of Structural Biology, Department of Infectious Diseases, Imperial College, London, SW7 2AZ, UK
| | - Thomas J McCorvie
- Section of Structural Biology, Department of Infectious Diseases, Imperial College, London, SW7 2AZ, UK
| | - Luke A Yates
- Section of Structural Biology, Department of Infectious Diseases, Imperial College, London, SW7 2AZ, UK
| | - Xiaodong Zhang
- Section of Structural Biology, Department of Infectious Diseases, Imperial College, London, SW7 2AZ, UK.
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55
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Design, synthesis and interaction of BRC4 analogous peptides with RAD51(241–260). Amino Acids 2019; 52:361-369. [DOI: 10.1007/s00726-019-02813-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 12/12/2019] [Indexed: 02/05/2023]
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56
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Špírek M, Mlcoušková J, Belán O, Gyimesi M, Harami GM, Molnár E, Novacek J, Kovács M, Krejci L. Human RAD51 rapidly forms intrinsically dynamic nucleoprotein filaments modulated by nucleotide binding state. Nucleic Acids Res 2019; 46:3967-3980. [PMID: 29481689 PMCID: PMC5934667 DOI: 10.1093/nar/gky111] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 02/08/2018] [Indexed: 12/31/2022] Open
Abstract
Formation of RAD51 filaments on single-stranded DNA is an essential event during homologous recombination, which is required for homology search, strand exchange and protection of replication forks. Formation of nucleoprotein filaments (NF) is required for development and genomic stability, and its failure is associated with developmental abnormalities and tumorigenesis. Here we describe the structure of the human RAD51 NFs and of its Walker box mutants using electron microscopy. Wild-type RAD51 filaments adopt an ‘open’ conformation when compared to a ‘closed’ structure formed by mutants, reflecting alterations in helical pitch. The kinetics of formation/disassembly of RAD51 filaments show rapid and high ssDNA coverage via low cooperativity binding of RAD51 units along the DNA. Subsequently, a series of isomerization or dissociation events mediated by nucleotide binding state creates intrinsically dynamic RAD51 NFs. Our findings highlight important a mechanistic divergence among recombinases from different organisms, in line with the diversity of biological mechanisms of HR initiation and quality control. These data reveal unexpected intrinsic dynamic properties of the RAD51 filament during assembly/disassembly, which may be important for the proper control of homologous recombination.
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Affiliation(s)
- Mário Špírek
- Department of Biology, Masaryk University, Brno 62500, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital Brno, Brno 65691, Czech Republic
| | - Jarmila Mlcoušková
- Department of Biology, Masaryk University, Brno 62500, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital Brno, Brno 65691, Czech Republic
| | - Ondrej Belán
- Department of Biology, Masaryk University, Brno 62500, Czech Republic
| | - Máté Gyimesi
- Department of Biochemistry, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Gábor M Harami
- Department of Biochemistry, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Eszter Molnár
- Department of Biochemistry, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Jiri Novacek
- CEITEC, Masaryk University, Brno, Czech Republic
| | - Mihály Kovács
- Department of Biochemistry, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Lumir Krejci
- Department of Biology, Masaryk University, Brno 62500, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital Brno, Brno 65691, Czech Republic.,National Centre for Biomolecular Research, Masaryk University, Brno 62500, Czech Republic
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57
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Haas KT, Lee M, Esposito A, Venkitaraman AR. Single-molecule localization microscopy reveals molecular transactions during RAD51 filament assembly at cellular DNA damage sites. Nucleic Acids Res 2019; 46:2398-2416. [PMID: 29309696 PMCID: PMC5861458 DOI: 10.1093/nar/gkx1303] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 12/19/2017] [Indexed: 11/14/2022] Open
Abstract
RAD51 recombinase assembles on single-stranded (ss)DNA substrates exposed by DNA end-resection to initiate homologous recombination (HR), a process fundamental to genome integrity. RAD51 assembly has been characterized using purified proteins, but its ultrastructural topography in the cell nucleus is unexplored. Here, we combine cell genetics with single-molecule localization microscopy and a palette of bespoke analytical tools, to visualize molecular transactions during RAD51 assembly in the cellular milieu at resolutions approaching 30-40 nm. In several human cell types, RAD51 focalizes in clusters that progressively extend into long filaments, which abut-but do not overlap-with globular bundles of replication protein A (RPA). Extended filaments alter topographically over time, suggestive of succeeding steps in HR. In cells depleted of the tumor suppressor protein BRCA2, or overexpressing its RAD51-binding BRC repeats, RAD51 fails to assemble at damage sites, although RPA accumulates unhindered. By contrast, in cells lacking a BRCA2 carboxyl (C)-terminal region targeted by cancer-causing mutations, damage-induced RAD51 assemblies initiate but do not extend into filaments. We suggest a model wherein RAD51 assembly proceeds concurrently with end-resection at adjacent sites, via an initiation step dependent on the BRC repeats, followed by filament extension through the C-terminal region of BRCA2.
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Affiliation(s)
- Kalina T Haas
- The Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - MiYoung Lee
- The Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Alessandro Esposito
- The Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Ashok R Venkitaraman
- The Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
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58
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Son MY, Hasty P. Homologous recombination defects and how they affect replication fork maintenance. AIMS GENETICS 2019; 5:192-211. [PMID: 31435521 PMCID: PMC6690234 DOI: 10.3934/genet.2018.4.192] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 03/18/2019] [Indexed: 01/07/2023]
Abstract
Homologous recombination (HR) repairs DNA double strand breaks (DSBs) and stabilizes replication forks (RFs). RAD51 is the recombinase for the HR pathway. To preserve genomic integrity, RAD51 forms a filament on the 3' end of a DSB and on a single-stranded DNA (ssDNA) gap. But unregulated HR results in undesirable chromosomal rearrangements. This review describes the multiple mechanisms that regulate HR with a focus on those mechanisms that promote and contain RAD51 filaments to limit chromosomal rearrangements. If any of these pathways break down and HR becomes unregulated then disease, primarily cancer, can result.
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Affiliation(s)
- Mi Young Son
- Department of Molecular Medicine and Institute of Biotechnology, UT Health San Antonio, 15355 Lambda Drive, San Antonio, USA
| | - Paul Hasty
- Department of Molecular Medicine and Institute of Biotechnology, UT Health San Antonio, 15355 Lambda Drive, San Antonio, USA
- The Mays Cancer Center, USA
- Sam and Ann Barshop Institute for Longevity and Aging Studies, USA
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59
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Zhao W, Wiese C, Kwon Y, Hromas R, Sung P. The BRCA Tumor Suppressor Network in Chromosome Damage Repair by Homologous Recombination. Annu Rev Biochem 2019; 88:221-245. [PMID: 30917004 DOI: 10.1146/annurev-biochem-013118-111058] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mutations in the BRCA1 and BRCA2 genes predispose afflicted individuals to breast, ovarian, and other cancers. The BRCA-encoded products form complexes with other tumor suppressor proteins and with the recombinase enzyme RAD51 to mediate chromosome damage repair by homologous recombination and also to protect stressed DNA replication forks against spurious nucleolytic attrition. Understanding how the BRCA tumor suppressor network executes its biological functions would provide the foundation for developing targeted cancer therapeutics, but progress in this area has been greatly hampered by the challenge of obtaining purified BRCA complexes for mechanistic studies. In this article, we review how recent effort begins to overcome this technical challenge, leading to functional and structural insights into the biochemical attributes of these complexes and the multifaceted roles that they fulfill in genome maintenance. We also highlight the major mechanistic questions that remain.
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Affiliation(s)
- Weixing Zhao
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA.,Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229, USA; ,
| | - Claudia Wiese
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Youngho Kwon
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA.,Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229, USA; ,
| | - Robert Hromas
- Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas 78229, USA
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA.,Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229, USA; ,
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60
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Abstract
Homologous Recombination (HR) is a high-fidelity process with a range of biologic functions from generation of genetic diversity to repair of DNA double-strand breaks (DSBs). In mammalian cells, BRCA2 facilitates the polymerization of RAD51 onto ssDNA to form a presynaptic nucleoprotein filament. This filament can then strand invade a homologous dsDNA to form the displacement loop (D-loop) structure leading to the eventual DSB repair. Here, we have found that RAD51 in stoichiometric excess over ssDNA can cause D-loop disassembly in vitro; furthermore, we show that this RAD51 activity is countered by BRCA2. These results demonstrate that BRCA2 may have a previously unexpected activity: regulation of HR at a post-synaptic stage by modulating RAD51-mediated D-loop dissociation. Our in vitro results suggest a mechanistic underpinning of homeostasis between RAD51 and BRCA2, which is an important factor of HR in mammalian cells.
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61
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El-Khoury R, Hajj M, Khraibani J, Audi E, Monsef C, Farra C. Novel pleiotropic BRCA2 pathogenic variants in Lebanese families. Cancer Genet 2019; 231-232:32-35. [PMID: 30803554 DOI: 10.1016/j.cancergen.2018.12.005] [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: 04/20/2018] [Revised: 11/23/2018] [Accepted: 12/24/2018] [Indexed: 11/25/2022]
Abstract
BRCA1 and BRCA2 associated pathogenic variants are the major cause of familial cases of early onset breast and ovarian cancers. Here we report two novel heterozygous pathogenic variants in exons 18 and 11 of the BRCA2 gene in two Lebanese families. The double nucleotide insertion c.8052_8053dupAA was identified in a 38-year-old Lebanese woman diagnosed with a breast cancer. The patient had a family history of affected first degree relatives. The double nucleotide deletion c.4342_4343delAA was identified in a 67-year-old woman with ovarian cancer. The patient came from a family marked by the occurrence of variable cancers. Her two daughters were also found to carry the deleterious variant. Both genetic aberrations result in a framing error that leads to a premature stop codon giving rise to unstable or truncated proteins. We further discuss two non-mutually exclusive potential scenarios related to the resulting haploinsufficiency and variant-specific dominant negative phenotype that might explain, at least in part, the variable expressivity associated with BRCA2 pathogenic variants.
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Affiliation(s)
- Riyad El-Khoury
- Neuromuscular Diagnostic Laboratory, Department of Pathology & Laboratory Medicine, American University of Beirut Medical Center, Beirut, Lebanon
| | - Mirna Hajj
- Faculty of Medicine, St. George Health Complex, University of Balamand, Balamand Al Kurah, Lebanon
| | - Jinan Khraibani
- Medical Genetics Unit, Department of Pathology & Laboratory Medicine, American University of Beirut Medical Center, Beirut, Lebanon
| | - Emma Audi
- Medical Genetics Unit, Department of Pathology & Laboratory Medicine, American University of Beirut Medical Center, Beirut, Lebanon
| | - Carla Monsef
- Medical Genetics Unit, Department of Pathology & Laboratory Medicine, American University of Beirut Medical Center, Beirut, Lebanon
| | - Chantal Farra
- Medical Genetics Unit, Department of Pathology & Laboratory Medicine, American University of Beirut Medical Center, Beirut, Lebanon.
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62
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RAD-ical New Insights into RAD51 Regulation. Genes (Basel) 2018; 9:genes9120629. [PMID: 30551670 PMCID: PMC6316741 DOI: 10.3390/genes9120629] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 12/04/2018] [Accepted: 12/07/2018] [Indexed: 01/17/2023] Open
Abstract
The accurate repair of DNA is critical for genome stability and cancer prevention. DNA double-strand breaks are one of the most toxic lesions; however, they can be repaired using homologous recombination. Homologous recombination is a high-fidelity DNA repair pathway that uses a homologous template for repair. One central HR step is RAD51 nucleoprotein filament formation on the single-stranded DNA ends, which is a step required for the homology search and strand invasion steps of HR. RAD51 filament formation is tightly controlled by many positive and negative regulators, which are collectively termed the RAD51 mediators. The RAD51 mediators function to nucleate, elongate, stabilize, and disassemble RAD51 during repair. In model organisms, RAD51 paralogs are RAD51 mediator proteins that structurally resemble RAD51 and promote its HR activity. New functions for the RAD51 paralogs during replication and in RAD51 filament flexibility have recently been uncovered. Mutations in the human RAD51 paralogs (RAD51B, RAD51C, RAD51D, XRCC2, XRCC3, and SWSAP1) are found in a subset of breast and ovarian cancers. Despite their discovery three decades ago, few advances have been made in understanding the function of the human RAD51 paralogs. Here, we discuss the current perspective on the in vivo and in vitro function of the RAD51 paralogs, and their relationship with cancer in vertebrate models.
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63
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Cai M, Zhang H, Hou L, Gao W, Song Y, Cui X, Li C, Guan R, Ma J, Wang X, Han Y, Lv Y, Chen F, Wang P, Meng X, Fu S. Inhibiting homologous recombination decreases extrachromosomal amplification but has no effect on intrachromosomal amplification in methotrexate-resistant colon cancer cells. Int J Cancer 2018; 144:1037-1048. [PMID: 30070702 PMCID: PMC6586039 DOI: 10.1002/ijc.31781] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 02/23/2018] [Accepted: 07/24/2018] [Indexed: 01/08/2023]
Abstract
Gene amplification, which involves the two major topographical structures double minutes (DMs) and homegeneously stained region (HSR), is a common mechanism of treatment resistance in cancer and is initiated by DNA double‐strand breaks. NHEJ, one of DSB repair pathways, is involved in gene amplification as we demonstrated previously. However, the involvement of homologous recombination, another DSB repair pathway, in gene amplification remains to be explored. To better understand the association between HR and gene amplification, we detected HR activity in DM‐ and HSR‐containing MTX‐resistant HT‐29 colon cancer cells. In DM‐containing MTX‐resistant cells, we found increased homologous recombination activity compared with that in MTX‐sensitive cells. Therefore, we suppressed HR activity by silencing BRCA1, the key player in the HR pathway. The attenuation of HR activity decreased the numbers of DMs and DM‐form amplified gene copies and increased the exclusion of micronuclei and nuclear buds that contained DM‐form amplification; these changes were accompanied by cell cycle acceleration and increased MTX sensitivity. In contrast, BRCA1 silencing did not influence the number of amplified genes and MTX sensitivity in HSR‐containing MTX‐resistant cells. In conclusion, our results suggest that the HR pathway plays different roles in extrachromosomal and intrachromosomal gene amplification and may be a new target to improve chemotherapeutic outcome by decreasing extrachromosomal amplification in cancer. What's new? Double‐strand DNA breaks (DSBs) initiate gene amplification, a phenomenon associated with therapeutic resistance in cancer that involves two topographical structures, double minutes (DMs) and homogeneously staining regions (HSRs). Whether DSB repair pathways, particularly homologous recombination (HR), also influence gene amplification is unknown. Here, in methotrexate‐resistant colon cancer cells, HR inhibition effectively reduced gene amplification, specifically the DM‐form, by blocking DM formation and promoting DM exclusion via micronuclei. HR inhibition had no influence on the HSR‐form of gene amplification. Loss of gene amplification by HR inhibition, through partial reversal of methotrexate resistance, may contribute to improved chemotherapeutic outcome.
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Affiliation(s)
- Mengdi Cai
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Huishu Zhang
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Liqing Hou
- Department of Genetics, Inner Mongolia Maternal and Child Care Hospital, Hohhot, Inner Mongolia Autonomous Region, China
| | - Wei Gao
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Ying Song
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Xiaobo Cui
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Chunxiang Li
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Rongwei Guan
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Jinfa Ma
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Xu Wang
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Yue Han
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Yafan Lv
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Feng Chen
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Ping Wang
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Xiangning Meng
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Songbin Fu
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
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64
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Fanconi-Anemia-Associated Mutations Destabilize RAD51 Filaments and Impair Replication Fork Protection. Cell Rep 2018; 21:333-340. [PMID: 29020621 DOI: 10.1016/j.celrep.2017.09.062] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Revised: 08/25/2017] [Accepted: 09/18/2017] [Indexed: 12/13/2022] Open
Abstract
Fanconi anemia (FA) is a genetic disorder characterized by a defect in DNA interstrand crosslink (ICL) repair, chromosomal instability, and a predisposition to cancer. Recently, two RAD51 mutations were reported to cause an FA-like phenotype. Despite the tight association of FA/HR proteins with replication fork (RF) stabilization during normal replication, it remains unknown how FA-associated RAD51 mutations affect replication beyond ICL lesions. Here, we report that these mutations fail to protect nascent DNA from MRE11-mediated degradation during RF stalling in Xenopus laevis egg extracts. Reconstitution of DNA protection in vitro revealed that the defect arises directly due to altered RAD51 properties. Both mutations induce pronounced structural changes and RAD51 filament destabilization that is not rescued by prevention of ATP hydrolysis due to aberrant ATP binding. Our results further interconnect the FA pathway with DNA replication and provide mechanistic insight into the role of RAD51 in recombination-independent mechanisms of genome maintenance.
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65
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Bhat KP, Cortez D. RPA and RAD51: fork reversal, fork protection, and genome stability. Nat Struct Mol Biol 2018; 25:446-453. [PMID: 29807999 PMCID: PMC6006513 DOI: 10.1038/s41594-018-0075-z] [Citation(s) in RCA: 233] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 04/23/2018] [Accepted: 04/26/2018] [Indexed: 01/23/2023]
Abstract
Replication protein A (RPA) and RAD51 are DNA-binding proteins that help maintain genome stability during DNA replication. These proteins regulate nucleases, helicases, DNA translocases, and signaling proteins to control replication, repair, recombination, and the DNA damage response. Their different DNA-binding mechanisms, enzymatic activities, and binding partners provide unique functionalities that cooperate to ensure that the appropriate activities are deployed at the right time to overcome replication challenges. Here we review and discuss the latest discoveries of the mechanisms by which these proteins work to preserve genome stability, with a focus on their actions in fork reversal and fork protection.
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Affiliation(s)
- Kamakoti P Bhat
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - David Cortez
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
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66
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Trenner A, Godau J, Sartori AA. A Short BRCA2-Derived Cell-Penetrating Peptide Targets RAD51 Function and Confers Hypersensitivity toward PARP Inhibition. Mol Cancer Ther 2018; 17:1392-1404. [PMID: 29654063 DOI: 10.1158/1535-7163.mct-17-1156] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 03/01/2018] [Accepted: 04/04/2018] [Indexed: 11/16/2022]
Abstract
Under conditions of genotoxic stress, cancer cells strongly rely on efficient DNA repair to survive and proliferate. The human BRCA2 tumor suppressor protein is indispensable for the repair of DNA double-strand breaks by homologous recombination (HR) by virtue of its ability to promote RAD51 loading onto single-stranded DNA. Therefore, blocking the interaction between BRCA2 and RAD51 could significantly improve the efficacy of conventional anticancer therapies. However, targeting protein-protein interaction (PPI) interfaces has proven challenging because flat and large PPI surfaces generally do not support binding of small-molecule inhibitors. In contrast, peptides are more potent for targeting PPIs but are otherwise difficult to deliver into cells. Here, we report that a synthetic 16-mer peptide derived from the BRC4 repeat motif of BRCA2 is capable of blocking RAD51 binding to BRCA2. Efficient noncytotoxic cellular uptake of a nona-arginine (R9)-conjugated version of the BRC4 peptide interferes with DNA damage-induced RAD51 foci formation and HR. Moreover, transduction of the BRC4 peptide impairs replication fork-protective function of BRCA2 and triggers MRE11-dependent degradation of nascent DNA in response to DNA replication stress. Finally, the BRC4 cell-penetrating peptide (CPP) confers selective hypersensitivity to PARP inhibition in cancer cells but spares noncancerous cells. Taken together, our data highlight an innovative approach to develop novel peptide-based DNA repair inhibitors and establish BRCA2-derived CPPs as promising anticancer agents. Mol Cancer Ther; 17(7); 1392-404. ©2018 AACR.
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Affiliation(s)
- Anika Trenner
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Julia Godau
- 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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67
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Caputo SM, Léone M, Damiola F, Ehlen A, Carreira A, Gaidrat P, Martins A, Brandão RD, Peixoto A, Vega A, Houdayer C, Delnatte C, Bronner M, Muller D, Castera L, Guillaud-Bataille M, Søkilde I, Uhrhammer N, Demontety S, Tubeuf H, Castelain G, Jensen UB, Petitalot A, Krieger S, Lefol C, Moncoutier V, Boutry-Kryza N, Nielsen HR, Sinilnikova O, Stoppa-Lyonnet D, Spurdle AB, Teixeira MR, Coulet F, Thomassen M, Rouleau E. Full in-frame exon 3 skipping of BRCA2 confers high risk of breast and/or ovarian cancer. Oncotarget 2018; 9:17334-17348. [PMID: 29707112 PMCID: PMC5915120 DOI: 10.18632/oncotarget.24671] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 02/24/2018] [Indexed: 12/18/2022] Open
Abstract
Germline pathogenic variants in the BRCA2 gene are associated with a cumulative high risk of breast/ovarian cancer. Several BRCA2 variants result in complete loss of the exon-3 at the transcript level. The pathogenicity of these variants and the functional impact of loss of exon 3 have yet to be established. As a collaboration of the COVAR clinical trial group (France), and the ENIGMA consortium for investigating breast cancer gene variants, this study evaluated 8 BRCA2 variants resulting in complete deletion of exon 3. Clinical information for 39 families was gathered from Portugal, France, Denmark and Sweden. Multifactorial likelihood analyses were conducted using information from 293 patients, for 7 out of the 8 variants (including 6 intronic). For all variants combined the likelihood ratio in favor of causality was 4.39*1025. These results provide convincing evidence for the pathogenicity of all examined variants that lead to a total exon 3 skipping, and suggest that other variants that result in complete loss of exon 3 at the molecular level could be associated with a high risk of cancer comparable to that associated with classical pathogenic variants in BRCA1 or BRCA2 gene. In addition, our functional study shows, for the first time, that deletion of exon 3 impairs the ability of cells to survive upon Mitomycin-C treatment, supporting lack of function for the altered BRCA2 protein in these cells. Finally, this study demonstrates that any variant leading to expression of only BRCA2 delta-exon 3 will be associated with an increased risk of breast and ovarian cancer.
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Affiliation(s)
| | - Mélanie Léone
- Unité Mixte de Génétique Constitutionnelle des Cancers Fréquents, Hospices Civils de Lyon/Centre Léon Bérard, Lyon, France
| | | | - Asa Ehlen
- Institut Curie, PSL Research University, CNRS UMR3348, Orsay, France.,Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, Orsay, France
| | - Aura Carreira
- Institut Curie, PSL Research University, CNRS UMR3348, Orsay, France.,Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, Orsay, France
| | - Pascaline Gaidrat
- Inserm-U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Alexandra Martins
- Inserm-U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | | | - Ana Peixoto
- Department of Genetics, Portuguese Oncology Institute, Porto, Portugal
| | - Ana Vega
- Department of Genetics, Portuguese Oncology Institute, Porto, Portugal
| | - Claude Houdayer
- Institut Curie, Service de Génétique, Paris, France.,Université Paris Descartes, Paris, France
| | | | | | - Danièle Muller
- Laboratoire d'Oncogénétique, Centre Paul Strauss, Strasbourg, France
| | - Laurent Castera
- Laboratoire de biologie et de génétique du cancer, CLCC François Baclesse, INSERM 1079 Centre Normand de Génomique et de Médecine Personnalisée, Caen, France
| | | | - Inge Søkilde
- Section of Molecular Diagnostics, Department of Clinical Biochemistry, Aalborg University Hospital, Aalborg, Denmark
| | - Nancy Uhrhammer
- Laboratoire de Biologie Médicale, CLCC Jean Perrin, Clermont-Ferrand, France
| | | | - Hélène Tubeuf
- Inserm-U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France.,Interactive Biosoftware, Rouen, France
| | - Gaïa Castelain
- Inserm-U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | | | - Uffe Birk Jensen
- Department of Clinical Genetics, Aarhus University Hospital, Aarhus, Denmark
| | | | - Sophie Krieger
- Laboratoire de biologie et de génétique du cancer, CLCC François Baclesse, INSERM 1079 Centre Normand de Génomique et de Médecine Personnalisée, Caen, France
| | | | | | - Nadia Boutry-Kryza
- Unité Mixte de Génétique Constitutionnelle des Cancers Fréquents, Hospices Civils de Lyon/Centre Léon Bérard, Lyon, France
| | | | - Olga Sinilnikova
- Unité Mixte de Génétique Constitutionnelle des Cancers Fréquents, Hospices Civils de Lyon/Centre Léon Bérard, Lyon, France
| | | | - Amanda B Spurdle
- Genetics and Comp utational Biology Division, QIMR Berghofer Medical Research Institute, Herston, Brisbane, Australia
| | - Manuel R Teixeira
- Department of Genetics, Portuguese Oncology Institute, Porto, Portugal.,Institute of Biomedical Sciences, University of Porto, Porto, Portugal
| | - Florence Coulet
- Laboratoire d'Oncogénétique et d'Angiogénétique Moléculaire, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Mads Thomassen
- Department of Clinical Genetics, Odense University Hospital, Odense, Denmark
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68
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Andriuskevicius T, Kotenko O, Makovets S. Putting together and taking apart: assembly and disassembly of the Rad51 nucleoprotein filament in DNA repair and genome stability. Cell Stress 2018; 2:96-112. [PMID: 31225474 PMCID: PMC6551702 DOI: 10.15698/cst2018.05.134] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Homologous recombination is a key mechanism providing both genome stability and genetic diversity in all living organisms. Recombinases play a central role in this pathway: multiple protein subunits of Rad51 or its orthologues bind single-stranded DNA to form a nucleoprotein filament which is essential for initiating recombination events. Multiple factors are involved in the regulation of this step, both positively and negatively. In this review, we discuss Rad51 nucleoprotein assembly and disassembly, how it is regulated and what functional significance it has in genome maintenance.
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Affiliation(s)
| | - Oleksii Kotenko
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh
| | - Svetlana Makovets
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh
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69
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Brouwer I, Moschetti T, Candelli A, Garcin EB, Modesti M, Pellegrini L, Wuite GJ, Peterman EJ. Two distinct conformational states define the interaction of human RAD51-ATP with single-stranded DNA. EMBO J 2018; 37:embj.201798162. [PMID: 29507080 PMCID: PMC5881629 DOI: 10.15252/embj.201798162] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 02/07/2018] [Accepted: 02/08/2018] [Indexed: 12/14/2022] Open
Abstract
An essential mechanism for repairing DNA double‐strand breaks is homologous recombination (HR). One of its core catalysts is human RAD51 (hRAD51), which assembles as a helical nucleoprotein filament on single‐stranded DNA, promoting DNA‐strand exchange. Here, we study the interaction of hRAD51 with single‐stranded DNA using a single‐molecule approach. We show that ATP‐bound hRAD51 filaments can exist in two different states with different contour lengths and with a free‐energy difference of ~4 kBT per hRAD51 monomer. Upon ATP hydrolysis, the filaments convert into a disassembly‐competent ADP‐bound configuration. In agreement with the single‐molecule analysis, we demonstrate the presence of two distinct protomer interfaces in the crystal structure of a hRAD51‐ATP filament, providing a structural basis for the two conformational states of the filament. Together, our findings provide evidence that hRAD51‐ATP filaments can exist in two interconvertible conformational states, which might be functionally relevant for DNA homology recognition and strand exchange.
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Affiliation(s)
- Ineke Brouwer
- Department of Physics and Astronomy and LaserLaB, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | | | - Andrea Candelli
- Department of Physics and Astronomy and LaserLaB, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Edwige B Garcin
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université, Marseille, France
| | - Mauro Modesti
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université, Marseille, France
| | - Luca Pellegrini
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Gijs Jl Wuite
- Department of Physics and Astronomy and LaserLaB, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Erwin Jg Peterman
- Department of Physics and Astronomy and LaserLaB, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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70
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Difference in Risk of Breast and Ovarian Cancer According to Putative Functional Domain Regions in Korean BRCA1/2 Mutation Carriers. Clin Breast Cancer 2018; 18:362-373.e1. [PMID: 29673794 DOI: 10.1016/j.clbc.2018.02.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Accepted: 02/10/2018] [Indexed: 12/13/2022]
Abstract
INTRODUCTION We investigated the relative risk of breast and ovarian cancers related to the putative functional domain regions, obesity, and parity among Korean BRCA1/2 mutation carriers. PATIENTS AND METHODS We analyzed the clinical characteristics, cancer history, and mutations according to the putative functional domain of BRCA proteins among 229 women with BRCA1/2 mutations who were treated at Yonsei Cancer Center, Severance Hospital between January 2009 and March 2017. RESULTS Twenty-two carriers (18.8% of 117 BRCA1 mutation carriers) with mutations located in the BRCT domain region had a higher risk of breast cancers (hazard ratio [HR], 2.851; 95% confidence interval [CI], 1.614-5.039; P < .001) than those with mutations outside of the putative functional domains of BRCA1. The risk of ovarian cancer was increased in 13 (11.6%) of 112 BRCA2 mutation carriers, with mutations located on BRC repeat regions (HR, 3.129; 95% CI, 1.123-8.720; P = .029). The term-pregnancies number was a significant risk-reducing factor for breast cancers in BRCA1 mutation carriers (HR per pregnancy, 0.640; 95% CI, 0.508-0.806; P < .001), for breast cancers in BRCA2 mutation carriers (HR per pregnancy, 0.534; 95% CI, 0.419-0.681; P < .001), and for ovarian cancers for BRCA1 mutation carriers (HR per pregnancy, 0.625; 95% CI, 0.474-0.824; P = .001). CONCLUSION Among Korean women with the BRCA1/2 mutation, the location of the mutations may influence the risk of breast and ovarian cancers according to the putative functional domain regions. Further investigations are required for risk prediction and preventive strategies in the BRCA1/2 mutation carriers.
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71
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Ranjha L, Howard SM, Cejka P. Main steps in DNA double-strand break repair: an introduction to homologous recombination and related processes. Chromosoma 2018; 127:187-214. [PMID: 29327130 DOI: 10.1007/s00412-017-0658-1] [Citation(s) in RCA: 193] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 12/15/2017] [Accepted: 12/19/2017] [Indexed: 12/16/2022]
Abstract
DNA double-strand breaks arise accidentally upon exposure of DNA to radiation and chemicals or result from faulty DNA metabolic processes. DNA breaks can also be introduced in a programmed manner, such as during the maturation of the immune system, meiosis, or cancer chemo- or radiotherapy. Cells have developed a variety of repair pathways, which are fine-tuned to the specific needs of a cell. Accordingly, vegetative cells employ mechanisms that restore the integrity of broken DNA with the highest efficiency at the lowest cost of mutagenesis. In contrast, meiotic cells or developing lymphocytes exploit DNA breakage to generate diversity. Here, we review the main pathways of eukaryotic DNA double-strand break repair with the focus on homologous recombination and its various subpathways. We highlight the differences between homologous recombination and end-joining mechanisms including non-homologous end-joining and microhomology-mediated end-joining and offer insights into how these pathways are regulated. Finally, we introduce noncanonical functions of the recombination proteins, in particular during DNA replication stress.
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Affiliation(s)
- Lepakshi Ranjha
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | - Sean M Howard
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland. .,Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland.
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72
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Horiuchi Y, Lin J, Shinojima Y, Fujiwara K, Moriyama M, Nagase H. Characterizing key nucleotide polymorphisms of hepatitis C virus-disease associations via mass-spectrometric genotyping. Int J Oncol 2017; 52:441-452. [PMID: 29207078 DOI: 10.3892/ijo.2017.4209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 10/16/2017] [Indexed: 11/06/2022] Open
Abstract
As more than 80% of hepatocellular carcinoma patients in Japan also suffer from hepatitis C virus infections some time in their medical history, identifying genetic aberrations associated to hepatitis C virulence in these individuals remains a high priority in the diagnosis and treatment of hepatocellular carcinoma. From the BioBank Japan Project, we acquired 480 subjects of hepatocellular carcinoma, chronic hepatitis and liver cirrhosis, and genotyped 131 clinically relevant host single nucleotide polymorphisms to survey the potential association between certain risk alleles and genes to a patient's predisposition to hepatitis C and liver cancer. Among those polymorphisms, we found 12 candidates with statistical significance to support association with hepatitis C virus susceptibility and genetic predisposition to hepatocellular carcinoma. SNPs in genes such as XPC, FANCA, KDR and BRCA2 also suggested likely connections between hepatitis C virus susceptibility and the contraction of liver diseases. Single nucleotide polymorphisms reported here provided suggestions for genes as biomarkers and elucidated insights briefing the linkage of hepatitis C virulence to the alteration of healthy liver genomic landscape as well as liver disease progression.
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Affiliation(s)
- Yuta Horiuchi
- Institute of Gastroenterology, Nihon University School of Medicine, Itabashi-ku, Tokyo 173-8610, Japan
| | - Jason Lin
- Laboratory of Cancer Genetics, Chiba Cancer Center Research Institute, Chuo-ku, Chiba 260-8717, Japan
| | - Yui Shinojima
- Department of Cancer Genetics, Nihon University School of Medicine, Itabashi-ku, Tokyo 173-8610, Japan
| | - Kyoko Fujiwara
- Department of Cancer Genetics, Nihon University School of Medicine, Itabashi-ku, Tokyo 173-8610, Japan
| | - Mitsuhiko Moriyama
- Institute of Gastroenterology, Nihon University School of Medicine, Itabashi-ku, Tokyo 173-8610, Japan
| | - Hiroki Nagase
- Laboratory of Cancer Genetics, Chiba Cancer Center Research Institute, Chuo-ku, Chiba 260-8717, Japan
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73
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Falchi F, Giacomini E, Masini T, Boutard N, Di Ianni L, Manerba M, Farabegoli F, Rossini L, Robertson J, Minucci S, Pallavicini I, Di Stefano G, Roberti M, Pellicciari R, Cavalli A. Synthetic Lethality Triggered by Combining Olaparib with BRCA2-Rad51 Disruptors. ACS Chem Biol 2017; 12:2491-2497. [PMID: 28841282 DOI: 10.1021/acschembio.7b00707] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In BRCA2-defective cells, poly(adenosine diphosphate [ADP]-ribose) polymerase inhibitors can trigger synthetic lethality, as two independent DNA-repairing mechanisms are simultaneously impaired. Here, we have pharmacologically induced synthetic lethality, which was triggered by combining two different small organic molecules. When administered with a BRCA2-Rad51 disruptor in nonmutant cells, Olaparib showed anticancer activity comparable to that shown when administered alone in BRCA2-defective cells. This strategy could represent an innovative approach to anticancer drug discovery and could be extended to other synthetic lethality pathways.
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Affiliation(s)
- Federico Falchi
- CompuNet, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova, Italy
| | - Elisa Giacomini
- CompuNet, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova, Italy
| | - Tiziana Masini
- CompuNet, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova, Italy
| | - Nicolas Boutard
- CompuNet, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova, Italy
| | - Lorenza Di Ianni
- Department
of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Via S. Giacomo 14, I-40126 Bologna, Italy
| | - Marcella Manerba
- Department
of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Via S. Giacomo 14, I-40126 Bologna, Italy
| | - Fulvia Farabegoli
- Department
of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro
6, I-40126 Bologna, Italy
| | - Lara Rossini
- TES Pharma S.r.l., Via Palmiro Togliatti 22bis, I-06073 Loc. Terrioli, Corciano, Perugia, Italy
| | - Janet Robertson
- TES Pharma S.r.l., Via Palmiro Togliatti 22bis, I-06073 Loc. Terrioli, Corciano, Perugia, Italy
| | - Saverio Minucci
- Department
of Experimental Oncology at the European Institute of Oncology, IFOM-IEO Campus, Via Adamello 16, I-20100 Milan, Italy
- Department
of Biosciences, University of Milan, Via Celoria 26, I-20100 Milan, Italy
| | - Isabella Pallavicini
- Department
of Experimental Oncology at the European Institute of Oncology, IFOM-IEO Campus, Via Adamello 16, I-20100 Milan, Italy
| | - Giuseppina Di Stefano
- Department
of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Via S. Giacomo 14, I-40126 Bologna, Italy
| | - Marinella Roberti
- Department
of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro
6, I-40126 Bologna, Italy
| | - Roberto Pellicciari
- TES Pharma S.r.l., Via Palmiro Togliatti 22bis, I-06073 Loc. Terrioli, Corciano, Perugia, Italy
| | - Andrea Cavalli
- CompuNet, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova, Italy
- Department
of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro
6, I-40126 Bologna, Italy
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74
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Zhao L, So CWE. PARPi potentiates with current conventional therapy in MLL leukemia. Cell Cycle 2017; 16:1861-1869. [PMID: 28886273 PMCID: PMC5638355 DOI: 10.1080/15384101.2017.1288325] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 01/25/2017] [Indexed: 12/11/2022] Open
Abstract
Acute myeloid leukemias driven by MLL fusion proteins are commonly associated with poor prognosis and refractory treatment. Here, we provide evidence that olaparib can potentiate sensitivity of MLL leukemia cells to conventional chemotherapy and DNMT inhibitors offering new potential therapeutic strategies for MLL rearranged leukemias Using the primary mouse leukemia cells and human MLL-AF9 leukemic cell line, we demonstrate that treatment of MLL-AF9 leukemic cells with DNMT inhibitors or chemotherapies in combination with olaparib results in significant reduction in colony formation or cell growth while the single agent treatments had little impacts. Combining olaparib with DNMT inhibitor induce cell cycle block and apoptosis. Furthermore, we observe a significant increase in proportion of cells with >10 γH2AX DNA damage foci and double stranded breaks when treated with DNMT inhibitors or chemotherapy agents in combination with olaparib, thus providing possible mechanistic insights for the synergism.
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Affiliation(s)
- Lu Zhao
- Leukemia and Stem Cell Biology Group, Department of Haematological Medicine, King's College London, Denmark Hill campus, London UK
| | - Chi Wai Eric So
- Leukemia and Stem Cell Biology Group, Department of Haematological Medicine, King's College London, Denmark Hill campus, London UK
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75
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Elimam AA, Aabdein MEMM, Eldeen MEFM, Altayb HN, Taha MA, Nimir MN, Dafaalla MD, Alfaki MM, Abdelrahim MA, Abdalla AA, Mohammed MI, Ellaithi M, Hamid MMA, Hassan MAS. Monoallelic characteristic-bearing heterozygous L1053X in BRCA2 gene among Sudanese women with breast cancer. BMC MEDICAL GENETICS 2017; 18:85. [PMID: 28814288 PMCID: PMC5559773 DOI: 10.1186/s12881-017-0448-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 07/31/2017] [Indexed: 12/17/2022]
Abstract
Background Breast cancer (BC) is the most common type of cancer in women. Among many risk factors of BC, mutations in BRCA2 gene were found to be the primary cause in 5–10% of cases. The majority of deleterious mutations are frameshift or nonsense mutations. Most of the reported BRCA2 mutations are protein truncating mutations. Methods The study aimed to describe the pattern of mutations including single nucleotide polymorphisms (SNPs) and variants of the BRCA2 (exon11) gene among Sudanese women patients diagnosed with BC. In this study a specific region of BRCA2 exon 11 was targeted using PCR and DNA sequencing. Results Early onset cases 25/45 (55.6%) were premenopausal women with a mean age of 36.6 years. Multiparity was more frequent within the study amounting to 30 cases (66.6%), with a mean parity of 4.1. Ductal type tumor was the predominant type detected in 22 cases (48.8%) among the reported histotypes. A heterozygous monoallelic nonsense mutation at nucleotide 3385 was found in four patients out of 9, where TTA codon was converted into the stop codon TGA. Conclusion This study detected a monoallelic nonsense mutation in four Sudanese female patients diagnosed with early onset BC from different families. Further work is needed to demonstrate its usefulness in screening of BC.
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Affiliation(s)
- Alsmawal A Elimam
- Post-graduate College, Al-Neelain University, Khartoum, Sudan. .,Daoud Research Group, Khartoum, Sudan.
| | | | - Mohamed El-Fatih Moly Eldeen
- Department of Histopathology and Cytology, Faculty of Medical Laboratory Sciences, Alneelain University, Khartoum, Sudan
| | - Hisham N Altayb
- Faculty of medical laboratory, Sudan University of science and technology, Khartoum, Sudan.,Department of Bioinformatics, Africa City of Technology, Sudan University of Medical Science and Technology, Khartoum, Sudan
| | | | - Mohammed N Nimir
- Daoud Research Group, Khartoum, Sudan.,Institute of Endemic Diseases, University of Khartoum, Khartoum, Sudan
| | | | | | | | - Abdelmohaymin A Abdalla
- Daoud Research Group, Khartoum, Sudan.,Department of Internal Medicine, Faculty of Medicine, University of Khartoum, Khartoum, Sudan
| | | | | | | | - Mohamed Ahmed Salih Hassan
- Department of Bioinformatics, Africa City of Technology, Sudan University of Medical Science and Technology, Khartoum, Sudan
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76
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Zhao X, Wei C, Li J, Xing P, Li J, Zheng S, Chen X. Cell cycle-dependent control of homologous recombination. Acta Biochim Biophys Sin (Shanghai) 2017; 49:655-668. [PMID: 28541389 DOI: 10.1093/abbs/gmx055] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Indexed: 01/29/2023] Open
Abstract
DNA double-strand breaks (DSBs) are among the most deleterious type of DNA lesions threatening genome integrity. Homologous recombination (HR) and non-homologous end joining (NHEJ) are two major pathways to repair DSBs. HR requires a homologous template to direct DNA repair, and is generally recognized as a high-fidelity pathway. In contrast, NHEJ directly seals broken ends, but the repair product is often accompanied by sequence alterations. The choice of repair pathways is strictly controlled by the cell cycle. The occurrence of HR is restricted to late S to G2 phases while NHEJ operates predominantly in G1 phase, although it can act throughout most of the cell cycle. Deregulation of repair pathway choice can result in genotoxic consequences associated with cancers. How the cell cycle regulates the choice of HR and NHEJ has been extensively studied in the past decade. In this review, we will focus on the current progresses on how HR is controlled by the cell cycle in both Saccharomyces cerevisiae and mammals. Particular attention will be given to how cyclin-dependent kinases modulate DSB end resection, DNA damage checkpoint signaling, repair and processing of recombination intermediates. In addition, we will discuss recent findings on how HR is repressed in G1 and M phases by the cell cycle.
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Affiliation(s)
- Xin Zhao
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Chengwen Wei
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Jingjing Li
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Poyuan Xing
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Jingyao Li
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Sihao Zheng
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Xuefeng Chen
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
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Abstract
Brh2, the BRCA2 ortholog in the fungus Ustilago maydis, mediates delivery of Rad51 to DNA during the course of homology-directed DNA repair. Rad51 interacts with Brh2 through the highly conserved BRC element and through a second region termed CRE located at the extreme carboxy terminus. Dss1, a small intrinsically unstructured protein that interacts with Brh2, is crucial for its activity in DNA repair, but the mechanism of this regulation is uncertain. In previous studies, we found that interaction of Brh2 with DNA was strongly modulated by association with Dss1. Here we report that CRE influences interaction of Dss1 with Brh2 and that Dss1 status markedly alters interaction of Brh2 with Rad51. While it appears that a single Rad51 protomer associates with Brh2 in complex with Dss1, loss of Dss1 is accompanied by a large increase in the number of Rad51 protomers that can associate with Brh2. Concomitant with this buildup of Rad51, Brh2 loses its ability to bind DNA. These observations suggest a feedback circuit in which release of Dss1 from Brh2 as it binds DNA triggers nucleation of a short Rad51 oligomer on Brh2, which in turn promotes dissociation of Brh2 from the DNA.
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Affiliation(s)
- Qingwen Zhou
- Department of Microbiology and Immunology, Weill Cornell Medical College , New York, New York 10065, United States
| | - William K Holloman
- Department of Microbiology and Immunology, Weill Cornell Medical College , New York, New York 10065, United States
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78
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Gachechiladze M, Škarda J, Soltermann A, Joerger M. RAD51 as a potential surrogate marker for DNA repair capacity in solid malignancies. Int J Cancer 2017; 141:1286-1294. [PMID: 28477336 DOI: 10.1002/ijc.30764] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 04/19/2017] [Accepted: 04/25/2017] [Indexed: 12/29/2022]
Abstract
Targeting deficient mechanisms of cellular DNA repair still represents the basis for the treatment of the majority of solid tumors, and increased DNA repair capacity is a hallmark mechanism of resistance not only to DNA-damaging treatments such as cytotoxic drugs and radiotherapy, but also to small molecule targeted drugs such as inhibitors of poly-ADP ribose polymerase (PARP). Hence, there is substantial medical need for potent and convenient biomarkers of individual response to DNA-targeted treatment in personalized cancer care. RAD51 is a highly conserved protein that catalyzes DNA repair via homologous recombination, a major DNA repair pathway which directly modulates cellular sensitivity to DNA-damaging treatments. The clinical and biological significance of RAD51 protein expression is still under investigation. Pre-clinical studies consistently show the important role of nuclear RAD51 immunoreactivity in chemo- and radioresistance. Validating data from clinical trials however is limited at present, and some clinical studies show controversial results. This review gives a comprehensive overview on the current knowledge about the prognostic and predictive value of RAD51 protein expression and genetic variability in patients with solid malignancies.
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Affiliation(s)
- Mariam Gachechiladze
- Department of Clinical and Molecular Pathology, Institute of Translational and Molecular Medicine, Faculty of Medicine and Dentistry, Palacký University, Olomouc, Czech Republic
| | - Josef Škarda
- Department of Clinical and Molecular Pathology, Institute of Translational and Molecular Medicine, Faculty of Medicine and Dentistry, Palacký University, Olomouc, Czech Republic
| | - Alex Soltermann
- Department of Pathology and Molecular Pathology, University Hospital, Zurich, Switzerland
| | - Markus Joerger
- Department of Medical Oncology and Hematology, Cantonal Hospital, St.Gallen, Switzerland
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79
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Luo K, Li L, Li Y, Wu C, Yin Y, Chen Y, Deng M, Nowsheen S, Yuan J, Lou Z. A phosphorylation-deubiquitination cascade regulates the BRCA2-RAD51 axis in homologous recombination. Genes Dev 2016; 30:2581-2595. [PMID: 27941124 PMCID: PMC5204351 DOI: 10.1101/gad.289439.116] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 11/30/2016] [Indexed: 11/24/2022]
Abstract
Homologous recombination (HR) is one of the major DNA double-strand break (DSB) repair pathways in mammalian cells. Defects in HR trigger genomic instability and result in cancer predisposition. The defining step of HR is homologous strand exchange directed by the protein RAD51, which is recruited to DSBs by BRCA2. However, the regulation of the BRCA2-RAD51 axis remains unclear. Here we report that ubiquitination of RAD51 hinders RAD51-BRCA2 interaction, while deubiquitination of RAD51 facilitates RAD51-BRCA2 binding and RAD51 recruitment and thus is critical for proper HR. Mechanistically, in response to DNA damage, the deubiquitinase UCHL3 is phosphorylated and activated by ATM. UCHL3, in turn, deubiquitinates RAD51 and promotes the binding between RAD51 and BRCA2. Overexpression of UCHL3 renders breast cancer cells resistant to radiation and chemotherapy, while depletion of UCHL3 sensitizes cells to these treatments, suggesting a determinant role of UCHL3 in cancer therapy. Overall, we identify UCHL3 as a novel regulator of DNA repair and reveal a model in which a phosphorylation-deubiquitination cascade dynamically regulates the BRCA2-RAD51 pathway.
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Affiliation(s)
- Kuntian Luo
- Research Center for Translational Medicine, East Hospital, Tongji University School of Medicine, Shanghai 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai 200120, China.,Department of Oncology, Mayo Clinic, Rochester, Minnesota 55905, USA
| | - Lei Li
- Research Center for Translational Medicine, East Hospital, Tongji University School of Medicine, Shanghai 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Yunhui Li
- Research Center for Translational Medicine, East Hospital, Tongji University School of Medicine, Shanghai 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Chenming Wu
- Research Center for Translational Medicine, East Hospital, Tongji University School of Medicine, Shanghai 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Yujiao Yin
- Research Center for Translational Medicine, East Hospital, Tongji University School of Medicine, Shanghai 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Yuping Chen
- Research Center for Translational Medicine, East Hospital, Tongji University School of Medicine, Shanghai 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Min Deng
- Department of Oncology, Mayo Clinic, Rochester, Minnesota 55905, USA
| | - Somaira Nowsheen
- Medical Scientist Training Program, Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic School of Medicine, Rochester, Minnesota 55905, USA
| | - Jian Yuan
- Research Center for Translational Medicine, East Hospital, Tongji University School of Medicine, Shanghai 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai 200120, China.,Department of Oncology, Mayo Clinic, Rochester, Minnesota 55905, USA
| | - Zhenkun Lou
- Department of Oncology, Mayo Clinic, Rochester, Minnesota 55905, USA.,Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China
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80
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Korolev S. Advances in structural studies of recombination mediator proteins. Biophys Chem 2016; 225:27-37. [PMID: 27974172 DOI: 10.1016/j.bpc.2016.12.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/01/2016] [Accepted: 12/01/2016] [Indexed: 12/25/2022]
Abstract
Recombination mediator proteins (RMPs) are critical for genome integrity in all organisms. They include phage UvsY, prokaryotic RecF, -O, -R (RecFOR) and eukaryotic Rad52, Breast Cancer susceptibility 2 (BRCA2) and Partner and localizer of BRCA2 (PALB2) proteins. BRCA2 and PALB2 are tumor suppressors implicated in cancer. RMPs regulate binding of RecA-like recombinases to sites of DNA damage to initiate the most efficient non-mutagenic repair of broken chromosome and other deleterious DNA lesions. Mechanistically, RMPs stimulate a single-stranded DNA (ssDNA) hand-off from ssDNA binding proteins (ssbs) such as gp32, SSB and RPA, to recombinases, activating DNA repair only at the time and site of the damage event. This review summarizes structural studies of RMPs and their implications for understanding mechanism and function. Comparative analysis of RMPs is complicated due to their convergent evolution. In contrast to the evolutionary conserved ssbs and recombinases, RMPs are extremely diverse in sequence and structure. Structural studies are particularly important in such cases to reveal common features of the entire family and specific features of regulatory mechanisms for each member. All RMPs are characterized by specific DNA-binding domains and include variable protein interaction motifs. The complexity of such RMPs corresponds to the ever-growing number of DNA metabolism events they participate in under normal and pathological conditions and requires additional comprehensive structure-functional studies.
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Affiliation(s)
- S Korolev
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, 1100 S Grand Blvd., St. Louis, MO 63104, USA.
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81
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Moschetti T, Sharpe T, Fischer G, Marsh ME, Ng HK, Morgan M, Scott DE, Blundell TL, R. Venkitaraman A, Skidmore J, Abell C, Hyvönen M. Engineering Archeal Surrogate Systems for the Development of Protein-Protein Interaction Inhibitors against Human RAD51. J Mol Biol 2016; 428:4589-4607. [PMID: 27725183 PMCID: PMC5117717 DOI: 10.1016/j.jmb.2016.10.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 10/02/2016] [Accepted: 10/04/2016] [Indexed: 02/02/2023]
Abstract
Protein-protein interactions (PPIs) are increasingly important targets for drug discovery. Efficient fragment-based drug discovery approaches to tackle PPIs are often stymied by difficulties in the production of stable, unliganded target proteins. Here, we report an approach that exploits protein engineering to "humanise" thermophilic archeal surrogate proteins as targets for small-molecule inhibitor discovery and to exemplify this approach in the development of inhibitors against the PPI between the recombinase RAD51 and tumour suppressor BRCA2. As human RAD51 has proved impossible to produce in a form that is compatible with the requirements of fragment-based drug discovery, we have developed a surrogate protein system using RadA from Pyrococcus furiosus. Using a monomerised RadA as our starting point, we have adopted two parallel and mutually instructive approaches to mimic the human enzyme: firstly by mutating RadA to increase sequence identity with RAD51 in the BRC repeat binding sites, and secondly by generating a chimeric archaeal human protein. Both approaches generate proteins that interact with a fourth BRC repeat with affinity and stoichiometry comparable to human RAD51. Stepwise humanisation has also allowed us to elucidate the determinants of RAD51 binding to BRC repeats and the contributions of key interacting residues to this interaction. These surrogate proteins have enabled the development of biochemical and biophysical assays in our ongoing fragment-based small-molecule inhibitor programme and they have allowed us to determine hundreds of liganded structures in support of our structure-guided design process, demonstrating the feasibility and advantages of using archeal surrogates to overcome difficulties in handling human proteins.
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Affiliation(s)
- Tommaso Moschetti
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Timothy Sharpe
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Gerhard Fischer
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - May E. Marsh
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Hong Kin Ng
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Matthew Morgan
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Duncan E. Scott
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Tom L. Blundell
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Ashok R. Venkitaraman
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - John Skidmore
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Chris Abell
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Marko Hyvönen
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK,Corresponding author.
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82
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Piwko W, Mlejnkova LJ, Mutreja K, Ranjha L, Stafa D, Smirnov A, Brodersen MM, Zellweger R, Sturzenegger A, Janscak P, Lopes M, Peter M, Cejka P. The MMS22L-TONSL heterodimer directly promotes RAD51-dependent recombination upon replication stress. EMBO J 2016; 35:2584-2601. [PMID: 27797818 DOI: 10.15252/embj.201593132] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 10/02/2016] [Accepted: 10/06/2016] [Indexed: 11/09/2022] Open
Abstract
Homologous recombination (HR) is a key pathway that repairs DNA double-strand breaks (DSBs) and helps to restart stalled or collapsed replication forks. How HR supports replication upon genotoxic stress is not understood. Using in vivo and in vitro approaches, we show that the MMS22L-TONSL heterodimer localizes to replication forks under unperturbed conditions and its recruitment is increased during replication stress in human cells. MMS22L-TONSL associates with replication protein A (RPA)-coated ssDNA, and the MMS22L subunit directly interacts with the strand exchange protein RAD51. MMS22L is required for proper RAD51 assembly at DNA damage sites in vivo, and HR-mediated repair of stalled forks is abrogated in cells expressing a MMS22L mutant deficient in RAD51 interaction. Similar to the recombination mediator BRCA2, recombinant MMS22L-TONSL limits the assembly of RAD51 on dsDNA, which stimulates RAD51-ssDNA nucleoprotein filament formation and RAD51-dependent strand exchange activity in vitro Thus, by specifically regulating RAD51 activity at uncoupled replication forks, MMS22L-TONSL stabilizes perturbed replication forks by promoting replication fork reversal and stimulating their HR-mediated restart in vivo.
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Affiliation(s)
- Wojciech Piwko
- Department of Biology, Institute of Biochemistry ETH Zurich, Zurich, Switzerland
| | - Lucie J Mlejnkova
- Institute of Molecular Cancer Research University of Zurich, Zurich, Switzerland
| | - Karun Mutreja
- Institute of Molecular Cancer Research University of Zurich, Zurich, Switzerland
| | - Lepakshi Ranjha
- Institute of Molecular Cancer Research University of Zurich, Zurich, Switzerland
| | - Diana Stafa
- Department of Biology, Institute of Biochemistry ETH Zurich, Zurich, Switzerland
| | - Alexander Smirnov
- Institute of Molecular Cancer Research University of Zurich, Zurich, Switzerland
| | - Mia Ml Brodersen
- Department of Biology, Institute of Biochemistry ETH Zurich, Zurich, Switzerland
| | - Ralph Zellweger
- Institute of Molecular Cancer Research University of Zurich, Zurich, Switzerland
| | - Andreas Sturzenegger
- Institute of Molecular Cancer Research University of Zurich, Zurich, Switzerland
| | - Pavel Janscak
- Institute of Molecular Cancer Research University of Zurich, Zurich, Switzerland
| | - Massimo Lopes
- Institute of Molecular Cancer Research University of Zurich, Zurich, Switzerland
| | - Matthias Peter
- Department of Biology, Institute of Biochemistry ETH Zurich, Zurich, Switzerland
| | - Petr Cejka
- Institute of Molecular Cancer Research University of Zurich, Zurich, Switzerland
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83
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Katsuki Y, Takata M. Defects in homologous recombination repair behind the human diseases: FA and HBOC. Endocr Relat Cancer 2016; 23:T19-37. [PMID: 27550963 DOI: 10.1530/erc-16-0221] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 08/22/2016] [Indexed: 12/25/2022]
Abstract
Hereditary breast and ovarian cancer (HBOC) syndrome and a rare childhood disorder Fanconi anemia (FA) are caused by homologous recombination (HR) defects, and some of the causative genes overlap. Recent studies in this field have led to the exciting development of PARP inhibitors as novel cancer therapeutics and have clarified important mechanisms underlying genome instability and tumor suppression in HR-defective disorders. In this review, we provide an overview of the basic molecular mechanisms governing HR and DNA crosslink repair, highlighting BRCA2, and the intriguing relationship between HBOC and FA.
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Affiliation(s)
- Yoko Katsuki
- Laboratory of DNA Damage SignalingDepartment of Late Effects Studies, Radiation Biology Center, Kyoto University, Yoshidakonoecho, Sakyo-ku, Kyoto, Japan
| | - Minoru Takata
- Laboratory of DNA Damage SignalingDepartment of Late Effects Studies, Radiation Biology Center, Kyoto University, Yoshidakonoecho, Sakyo-ku, Kyoto, Japan
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84
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Tyrosine phosphorylation stimulates activity of human RAD51 recombinase through altered nucleoprotein filament dynamics. Proc Natl Acad Sci U S A 2016; 113:E6045-E6054. [PMID: 27671650 DOI: 10.1073/pnas.1604807113] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The DNA strand exchange protein RAD51 facilitates the central step in homologous recombination, a process fundamentally important for accurate repair of damaged chromosomes, restart of collapsed replication forks, and telomere maintenance. The active form of RAD51 is a nucleoprotein filament that assembles on single-stranded DNA (ssDNA) at the sites of DNA damage. The c-Abl tyrosine kinase and its oncogenic counterpart BCR-ABL fusion kinase phosphorylate human RAD51 on tyrosine residues 54 and 315. We combined biochemical reconstitutions of the DNA strand exchange reactions with total internal reflection fluorescence microscopy to determine how the two phosphorylation events affect the biochemical activities of human RAD51 and properties of the RAD51 nucleoprotein filament. By mimicking RAD51 tyrosine phosphorylation with a nonnatural amino acid, p-carboxymethyl-l-phenylalanine (pCMF), we demonstrated that Y54 phosphorylation enhances the RAD51 recombinase activity by at least two different mechanisms, modifies the RAD51 nucleoprotein filament formation, and allows RAD51 to compete efficiently with ssDNA binding protein RPA. In contrast, Y315 phosphorylation has little effect on the RAD51 activities. Based on our work and previous cellular studies, we propose a mechanism underlying RAD51 activation by c-Abl/BCR-ABL kinases.
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85
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von Nicolai C, Ehlén Å, Martin C, Zhang X, Carreira A. A second DNA binding site in human BRCA2 promotes homologous recombination. Nat Commun 2016; 7:12813. [PMID: 27628236 PMCID: PMC5027613 DOI: 10.1038/ncomms12813] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 08/03/2016] [Indexed: 12/19/2022] Open
Abstract
BRCA2 tumour-suppressor protein is well known for its role in DNA repair by homologous recombination (HR); assisting the loading of RAD51 recombinase at DNA double-strand breaks. This function is executed by the C-terminal DNA binding domain (CTD) which binds single-stranded (ss)DNA, and the BRC repeats, which bind RAD51 and modulate its assembly onto ssDNA. Paradoxically, analysis of cells resistant to DNA damaging agents missing the CTD restore HR proficiency, suggesting another domain may take over its function. Here, we identify a region in the N terminus of BRCA2 that exhibits DNA binding activity (NTD) and provide evidence for NTD promoting RAD51-mediated HR. A missense variant detected in breast cancer patients located in the NTD impairs HR stimulation on dsDNA/ssDNA junction containing substrates. These findings shed light on the function of the N terminus of BRCA2 and have implications for the evaluation of breast cancer variants. BRCA2 is a well-characterized central player in homologous recombination in which it functions as the RAD51 loader. Here the authors identify an N-terminal region of BRCA2 that binds DNA and promotes efficient DNA repair.
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Affiliation(s)
- Catharina von Nicolai
- Institut Curie, PSL Research University, UMR 3348, Genotoxic Stress and Cancer Unit, Research Center, Paris Sud University, Paris Saclay University, Centre Universitaire d'Orsay, Bâtiment 110, 91405 Orsay, France
| | - Åsa Ehlén
- Institut Curie, PSL Research University, UMR 3348, Genotoxic Stress and Cancer Unit, Research Center, Paris Sud University, Paris Saclay University, Centre Universitaire d'Orsay, Bâtiment 110, 91405 Orsay, France
| | - Charlotte Martin
- Institut Curie, PSL Research University, UMR 3348, Genotoxic Stress and Cancer Unit, Research Center, Paris Sud University, Paris Saclay University, Centre Universitaire d'Orsay, Bâtiment 110, 91405 Orsay, France
| | - Xiaodong Zhang
- Department of Medicine, Imperial College London, SAF Building, London SW7 2AZ, UK
| | - Aura Carreira
- Institut Curie, PSL Research University, UMR 3348, Genotoxic Stress and Cancer Unit, Research Center, Paris Sud University, Paris Saclay University, Centre Universitaire d'Orsay, Bâtiment 110, 91405 Orsay, France
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86
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Short JM, Liu Y, Chen S, Soni N, Madhusudhan MS, Shivji MKK, Venkitaraman AR. High-resolution structure of the presynaptic RAD51 filament on single-stranded DNA by electron cryo-microscopy. Nucleic Acids Res 2016; 44:9017-9030. [PMID: 27596592 PMCID: PMC5100573 DOI: 10.1093/nar/gkw783] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 08/24/2016] [Indexed: 12/21/2022] Open
Abstract
Homologous DNA recombination (HR) by the RAD51 recombinase enables error-free DNA break repair. To execute HR, RAD51 first forms a presynaptic filament on single-stranded (ss) DNA, which catalyses pairing with homologous double-stranded (ds) DNA. Here, we report a structure for the presynaptic human RAD51 filament at 3.5–5.0Å resolution using electron cryo-microscopy. RAD51 encases ssDNA in a helical filament of 103Å pitch, comprising 6.4 protomers per turn, with a rise of 16.1Å and a twist of 56.2°. Inter-protomer distance correlates with rotation of an α-helical region in the core catalytic domain that is juxtaposed to ssDNA, suggesting how the RAD51–DNA interaction modulates protomer spacing and filament pitch. We map Fanconi anaemia-like disease-associated RAD51 mutations, clarifying potential phenotypes. We predict binding sites on the presynaptic filament for two modules present in each BRC repeat of the BRCA2 tumour suppressor, a critical HR mediator. Structural modelling suggests that changes in filament pitch mask or expose one binding site with filament-inhibitory potential, rationalizing the paradoxical ability of the BRC repeats to either stabilize or inhibit filament formation at different steps during HR. Collectively, our findings provide fresh insight into the structural mechanism of HR and its dysregulation in human disease.
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Affiliation(s)
- Judith M Short
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Yang Liu
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Shaoxia Chen
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Neelesh Soni
- Indian Institute of Science, Education & Research, Dr Homi Babha Road, Pune 411 008, India
| | - Mallur S Madhusudhan
- Indian Institute of Science, Education & Research, Dr Homi Babha Road, Pune 411 008, India.,Bioinformatics Institute, A*STAR, 30 Biopolis Drive, 138671 Singapore
| | - Mahmud K K Shivji
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Ashok R Venkitaraman
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
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87
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Martinez JS, Baldeyron C, Carreira A. Molding BRCA2 function through its interacting partners. Cell Cycle 2016; 14:3389-95. [PMID: 26566862 DOI: 10.1080/15384101.2015.1093702] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The role of the tumor suppressor BRCA2 has been shaped over 2 decades thanks to the discovery of its protein and nucleic acid partners, biochemical and structural studies of the protein, and the functional evaluation of germline variants identified in breast cancer patients. Yet, the pathogenic and functional effect of many germline mutations in BRCA2 remains undetermined, and the heterogeneity of BRCA2-associated tumors challenges the identification of causative variants that drive tumorigenesis. In this review, we propose an overview of the established and emerging interacting partners and functional pathways attributed to BRCA2, and we speculate on how variants altering these functions may contribute to cancer susceptibility.
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Affiliation(s)
- Juan S Martinez
- a Institut Curie; Centre de Recherche ; Orsay , France.,b CNRS UMR3348; Genotoxic Stress and Cancer; Centre Universitaire ; Orsay , France
| | - Céline Baldeyron
- a Institut Curie; Centre de Recherche ; Orsay , France.,b CNRS UMR3348; Genotoxic Stress and Cancer; Centre Universitaire ; Orsay , France
| | - Aura Carreira
- a Institut Curie; Centre de Recherche ; Orsay , France.,b CNRS UMR3348; Genotoxic Stress and Cancer; Centre Universitaire ; Orsay , France
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88
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Polymorphisms in Cancer Susceptibility Genes XRCC1, RAD51 and TP53 and the Risk of Breast Cancer in Serbian Women. Int J Biol Markers 2016; 31:e258-63. [DOI: 10.5301/jbm.5000201] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/24/2016] [Indexed: 01/11/2023]
Abstract
Background Thanks to immense improvements in technology over the past few decades, we have witnessed a major shift towards the idea that breast cancer results from a combined effect of multiple common alleles conferring low risk. This study investigates the role of 3 nonsynonymous SNPs in the DNA repair genes XRCC1 (R399Q), RAD51 (G135C) and TP53 (Arg72Pro) in breast cancer in Serbian women. Patients and Methods Cases of BRCA1/2-negative hereditary breast cancer (n = 52), sporadic breast cancer (n = 106) and age-matched cancer-free female controls (n = 104) were obtained from the Institute for Oncology and Radiology of Serbia's blood bank. Restriction fragment length polymorphism analysis was used for genotyping. Descriptive analyses included genotype and allelic frequencies; the odds ratio and 95% confidence interval were calculated as an estimate of the relative risk. Results A significant difference in QQ+RQ versus RR genotype distribution of XRCC1 was observed between hereditary breast cancer patients and cancer-free controls. The association was confirmed among young breast cancer patients from these high-risk families. The existence of 3 recessive alleles in the RAD51 and XRCC1 genotype combination showed an association with hereditary breast cancer. Odds ratio analysis indicated a strong protective role of the RAD51 GG + TP53 ArgArg + XRCC1 RR combined genotype against hereditary breast cancer negative for BRCA1/2 mutations. Conclusions The XRCC1 R399Q polymorphism showed an association with increased breast cancer risk in Serbia, especially in the hereditary form of the disease and in young breast cancer patients. Dominant alleles of RAD51, TP53 and XRCC1 combined genotypes indicated a strong protective role against hereditary breast cancer.
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89
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Hengel SR, Malacaria E, Folly da Silva Constantino L, Bain FE, Diaz A, Koch BG, Yu L, Wu M, Pichierri P, Spies MA, Spies M. Small-molecule inhibitors identify the RAD52-ssDNA interaction as critical for recovery from replication stress and for survival of BRCA2 deficient cells. eLife 2016; 5. [PMID: 27434671 PMCID: PMC4982760 DOI: 10.7554/elife.14740] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 07/18/2016] [Indexed: 12/20/2022] Open
Abstract
The DNA repair protein RAD52 is an emerging therapeutic target of high importance for BRCA-deficient tumors. Depletion of RAD52 is synthetically lethal with defects in tumor suppressors BRCA1, BRCA2 and PALB2. RAD52 also participates in the recovery of the stalled replication forks. Anticipating that ssDNA binding activity underlies the RAD52 cellular functions, we carried out a high throughput screening campaign to identify compounds that disrupt the RAD52-ssDNA interaction. Lead compounds were confirmed as RAD52 inhibitors in biochemical assays. Computational analysis predicted that these inhibitors bind within the ssDNA-binding groove of the RAD52 oligomeric ring. The nature of the inhibitor-RAD52 complex was validated through an in silico screening campaign, culminating in the discovery of an additional RAD52 inhibitor. Cellular studies with our inhibitors showed that the RAD52-ssDNA interaction enables its function at stalled replication forks, and that the inhibition of RAD52-ssDNA binding acts additively with BRCA2 or MUS81 depletion in cell killing. DOI:http://dx.doi.org/10.7554/eLife.14740.001 Cells are constantly in danger of losing or scrambling critical genetic information because of DNA damage. To cope with this stress, cells have numerous DNA repair systems. One of these systems – homology-directed DNA repair – involves the proteins BRCA1 and BRCA2, which are often missing or defective in breast and ovarian cancers. The BRCA-deficient cancer cells can still survive, but become “addicted” to other DNA repair proteins – among them a protein called RAD52. It might be possible to kill these cancer cells using drugs that stop RAD52 from working. Such treatments would have the benefit of not harming normal healthy cells, as these cells contain working BRCA proteins and can survive without RAD52. It is not currently known exactly how RAD52 allows the BRCA-deficient cells to survive, but this probably depends on RAD52’s ability to bind to single strands of DNA. Small molecules that block the interaction between the RAD52 protein and DNA might therefore help to kill cancer cells. Hengel et al. developed a high throughput biophysical method to search through a large collection of small molecules to find those that prevent RAD52 from binding to DNA. The best potential drug leads were then tested in laboratory-grown human cells and using biophysical and biochemical techniques. Computational approaches were also used to model how these molecules block the interaction between RAD52 and DNA at the atomistic level. Hengel et al. then used the information about how the small molecules bind to RAD52 to perform further computational screening. This identified a natural compound that competes with single-stranded DNA to bind to RAD52. The activity of this molecule was then validated using biophysical methods. The methods used by Hengel et al. provide the foundation for further searches for new anticancer drugs. Future studies that employ the small molecule drugs identified so far will also help to determine exactly how RAD52 works in human cells and how it helps cancer cells to survive. DOI:http://dx.doi.org/10.7554/eLife.14740.002
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Affiliation(s)
- Sarah R Hengel
- Department of Biochemistry, University of Iowa, Iowa City, United States
| | - Eva Malacaria
- Department of Environment and Health, Section of Experimental and Computational Carcinogenesis, Istituto Superiore di Sanita, Rome, Italy
| | - Laura Folly da Silva Constantino
- Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa, Iowa City, United States
| | - Fletcher E Bain
- Department of Biochemistry, University of Iowa, Iowa City, United States
| | - Andrea Diaz
- Department of Biochemistry, University of Iowa, Iowa City, United States
| | - Brandon G Koch
- Department of Biochemistry, University of Iowa, Iowa City, United States
| | - Liping Yu
- Department of Biochemistry, University of Iowa, Iowa City, United States.,NMR Core Facility, Carver College of Medicine, University of Iowa, Iowa City, United States
| | - Meng Wu
- Department of Biochemistry, University of Iowa, Iowa City, United States.,Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa, Iowa City, United States.,High Throughput Screening Facility, University of Iowa, Iowa City, United States
| | - Pietro Pichierri
- Department of Environment and Health, Section of Experimental and Computational Carcinogenesis, Istituto Superiore di Sanita, Rome, Italy
| | - M Ashley Spies
- Department of Biochemistry, University of Iowa, Iowa City, United States.,Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa, Iowa City, United States
| | - Maria Spies
- Department of Biochemistry, University of Iowa, Iowa City, United States
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90
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DNA damage tolerance pathway involving DNA polymerase ι and the tumor suppressor p53 regulates DNA replication fork progression. Proc Natl Acad Sci U S A 2016; 113:E4311-9. [PMID: 27407148 DOI: 10.1073/pnas.1605828113] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
DNA damage tolerance facilitates the progression of replication forks that have encountered obstacles on the template strands. It involves either translesion DNA synthesis initiated by proliferating cell nuclear antigen monoubiquitination or less well-characterized fork reversal and template switch mechanisms. Herein, we characterize a novel tolerance pathway requiring the tumor suppressor p53, the translesion polymerase ι (POLι), the ubiquitin ligase Rad5-related helicase-like transcription factor (HLTF), and the SWI/SNF catalytic subunit (SNF2) translocase zinc finger ran-binding domain containing 3 (ZRANB3). This novel p53 activity is lost in the exonuclease-deficient but transcriptionally active p53(H115N) mutant. Wild-type p53, but not p53(H115N), associates with POLι in vivo. Strikingly, the concerted action of p53 and POLι decelerates nascent DNA elongation and promotes HLTF/ZRANB3-dependent recombination during unperturbed DNA replication. Particularly after cross-linker-induced replication stress, p53 and POLι also act together to promote meiotic recombination enzyme 11 (MRE11)-dependent accumulation of (phospho-)replication protein A (RPA)-coated ssDNA. These results implicate a direct role of p53 in the processing of replication forks encountering obstacles on the template strand. Our findings define an unprecedented function of p53 and POLι in the DNA damage response to endogenous or exogenous replication stress.
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91
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Abstract
The repair of DNA by homologous recombination is an essential, efficient, and high-fidelity process that mends DNA lesions formed during cellular metabolism; these lesions include double-stranded DNA breaks, daughter-strand gaps, and DNA cross-links. Genetic defects in the homologous recombination pathway undermine genomic integrity and cause the accumulation of gross chromosomal abnormalities-including rearrangements, deletions, and aneuploidy-that contribute to cancer formation. Recombination proceeds through the formation of joint DNA molecules-homologously paired but metastable DNA intermediates that are processed by several alternative subpathways-making recombination a versatile and robust mechanism to repair damaged chromosomes. Modern biophysical methods make it possible to visualize, probe, and manipulate the individual molecules participating in the intermediate steps of recombination, revealing new details about the mechanics of genetic recombination. We review and discuss the individual stages of homologous recombination, focusing on common pathways in bacteria, yeast, and humans, and place particular emphasis on the molecular mechanisms illuminated by single-molecule methods.
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Affiliation(s)
- Jason C Bell
- Department of Microbiology and Molecular Genetics, and Department of Molecular and Cellular Biology, University of California, Davis, California 95616;
| | - Stephen C Kowalczykowski
- Department of Microbiology and Molecular Genetics, and Department of Molecular and Cellular Biology, University of California, Davis, California 95616;
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92
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Chatterjee G, Jimenez-Sainz J, Presti T, Nguyen T, Jensen RB. Distinct binding of BRCA2 BRC repeats to RAD51 generates differential DNA damage sensitivity. Nucleic Acids Res 2016; 44:5256-70. [PMID: 27084934 PMCID: PMC4914107 DOI: 10.1093/nar/gkw242] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 03/29/2016] [Indexed: 01/01/2023] Open
Abstract
BRCA2 is a multi-faceted protein critical for the proper regulation of homology-directed repair of DNA double-strand breaks. Elucidating the mechanistic features of BRCA2 is crucial for understanding homologous recombination and how patient-derived mutations impact future cancer risk. Eight centrally located BRC repeats in BRCA2 mediate binding and regulation of RAD51 on resected DNA substrates. Herein, we dissect the biochemical and cellular features of the BRC repeats tethered to the DNA binding domain of BRCA2. To understand how the BRC repeats and isolated domains of BRCA2 contribute to RAD51 binding, we analyzed both the biochemical and cellular properties of these proteins. In contrast to the individual BRC repeat units, we find that the BRC5-8 region potentiates RAD51-mediated DNA strand pairing and provides complementation functions exceeding those of BRC repeats 1-4. Furthermore, BRC5-8 can efficiently repair nuclease-induced DNA double-strand breaks and accelerate the assembly of RAD51 repair complexes upon DNA damage. These findings highlight the importance of the BRC5-8 domain in stabilizing the RAD51 filament and promoting homology-directed repair under conditions of cellular DNA damage.
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Affiliation(s)
- Gouri Chatterjee
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Judit Jimenez-Sainz
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Thomas Presti
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Tiffany Nguyen
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Ryan B Jensen
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
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93
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Godin SK, Sullivan MR, Bernstein KA. Novel insights into RAD51 activity and regulation during homologous recombination and DNA replication. Biochem Cell Biol 2016; 94:407-418. [PMID: 27224545 DOI: 10.1139/bcb-2016-0012] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In this review we focus on new insights that challenge our understanding of homologous recombination (HR) and Rad51 regulation. Recent advances using high-resolution microscopy and single molecule techniques have broadened our knowledge of Rad51 filament formation and strand invasion at double-strand break (DSB) sites and at replication forks, which are one of most physiologically relevant forms of HR from yeast to humans. Rad51 filament formation and strand invasion is regulated by many mediator proteins such as the Rad51 paralogues and the Shu complex, consisting of a Shu2/SWS1 family member and additional Rad51 paralogues. Importantly, a novel RAD51 paralogue was discovered in Caenorhabditis elegans, and its in vitro characterization has demonstrated a new function for the worm RAD51 paralogues during HR. Conservation of the human RAD51 paralogues function during HR and repair of replicative damage demonstrate how the RAD51 mediators play a critical role in human health and genomic integrity. Together, these new findings provide a framework for understanding RAD51 and its mediators in DNA repair during multiple cellular contexts.
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Affiliation(s)
- Stephen K Godin
- University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, and the Department of Microbiology and Molecular Genetics.,University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, and the Department of Microbiology and Molecular Genetics
| | - Meghan R Sullivan
- University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, and the Department of Microbiology and Molecular Genetics.,University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, and the Department of Microbiology and Molecular Genetics
| | - Kara A Bernstein
- University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, and the Department of Microbiology and Molecular Genetics
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94
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BRCA2 regulates DMC1-mediated recombination through the BRC repeats. Proc Natl Acad Sci U S A 2016; 113:3515-20. [PMID: 26976601 DOI: 10.1073/pnas.1601691113] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
In somatic cells, BRCA2 is needed for RAD51-mediated homologous recombination. The meiosis-specific DNA strand exchange protein, DMC1, promotes the formation of DNA strand invasion products (joint molecules) between homologous molecules in a fashion similar to RAD51. BRCA2 interacts directly with both human RAD51 and DMC1; in the case of RAD51, this interaction results in stimulation of RAD51-promoted DNA strand exchange. However, for DMC1, little is known regarding the basis and functional consequences of its interaction with BRCA2. Here we report that human DMC1 interacts directly with each of the BRC repeats of BRCA2, albeit most tightly with repeats 1-3 and 6-8. However, BRC1-3 bind with higher affinity to RAD51 than to DMC1, whereas BRC6-8 bind with higher affinity to DMC1, providing potential spatial organization to nascent filament formation. With the exception of BRC4, each BRC repeat stimulates joint molecule formation by DMC1. The basis for this stimulation is an enhancement of DMC1-ssDNA complex formation by the stimulatory BRC repeats. Lastly, we demonstrate that full-length BRCA2 protein stimulates DMC1-mediated DNA strand exchange between RPA-ssDNA complexes and duplex DNA, thus identifying BRCA2 as a mediator of DMC1 recombination function. Collectively, our results suggest unique and specialized functions for the BRC motifs of BRCA2 in promoting homologous recombination in meiotic and mitotic cells.
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95
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Ochiai K, Ishiguro-Oonuma T, Yoshikawa Y, Udagawa C, Kato Y, Watanabe M, Bonkobara M, Morimatsu M, Omi T. Polymorphisms of canine BRCA2 BRC repeats affecting interaction with RAD51. Biomed Res 2016; 36:155-8. [PMID: 25876666 DOI: 10.2220/biomedres.36.155] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Mutations in the breast cancer susceptibility gene BRCA2 leading to the failure of interactions with the recombinase RAD51 are associated with an increased risk of cancer in humans. This interaction depends on the eight BRC repeat (BRC1-8) sequences in BRCA2. We previously reported that canine BRC3 has two polymorphisms (T1425P and K1435R) influencing the interaction with RAD51, and 1435R was identified in mammary tumor dog samples. In this study, we investigated the sequence variations of BRC3 and 4 in 236 dogs of five breeds. Allele frequencies of 1425P and 1435R were 0.063 and 0.314, respectively, and there was no other polymorphism in the sequenced region. A mammalian two-hybrid assay using BRC3-4 sequences demonstrated that 1425P allele reduced the binding strength with RAD51 but 1435R had no effect. These results may provide an insight into the functions of not only individual but also multiple BRC repeats of BRCA2 in dogs.
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Affiliation(s)
- Kazuhiko Ochiai
- Department of Veterinary Nursing and Technology, School of Veterinary Science, Nippon Veterinary and Life Science University
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96
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Esposito MT, Zhao L, Fung TK, Rane JK, Wilson A, Martin N, Gil J, Leung AY, Ashworth A, So CWE. Synthetic lethal targeting of oncogenic transcription factors in acute leukemia by PARP inhibitors. Nat Med 2015; 21:1481-90. [PMID: 26594843 DOI: 10.1038/nm.3993] [Citation(s) in RCA: 124] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 10/14/2015] [Indexed: 12/13/2022]
Abstract
Acute myeloid leukemia (AML) is mostly driven by oncogenic transcription factors, which have been classically viewed as intractable targets using small-molecule inhibitor approaches. Here we demonstrate that AML driven by repressive transcription factors, including AML1-ETO (encoded by the fusion oncogene RUNX1-RUNX1T1) and PML-RARα fusion oncoproteins (encoded by PML-RARA) are extremely sensitive to poly (ADP-ribose) polymerase (PARP) inhibition, in part owing to their suppressed expression of key homologous recombination (HR)-associated genes and their compromised DNA-damage response (DDR). In contrast, leukemia driven by mixed-lineage leukemia (MLL, encoded by KMT2A) fusions with dominant transactivation ability is proficient in DDR and insensitive to PARP inhibition. Intriguingly, genetic or pharmacological inhibition of an MLL downstream target, HOXA9, which activates expression of various HR-associated genes, impairs DDR and sensitizes MLL leukemia to PARP inhibitors (PARPis). Conversely, HOXA9 overexpression confers PARPi resistance to AML1-ETO and PML-RARα transformed cells. Together, these studies describe a potential utility of PARPi-induced synthetic lethality for leukemia treatment and reveal a novel molecular mechanism governing PARPi sensitivity in AML.
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MESH Headings
- Animals
- Apoptosis/drug effects
- Cell Differentiation/drug effects
- Cell Line, Transformed
- Cell Line, Tumor
- Cell Survival/drug effects
- Cellular Senescence/drug effects
- Core Binding Factor Alpha 2 Subunit/metabolism
- DNA Damage
- DNA Repair/drug effects
- Fluorescent Antibody Technique
- Gene Expression Regulation, Leukemic
- Homeodomain Proteins/metabolism
- Humans
- Leukemia, Myeloid, Acute/drug therapy
- Leukemia, Myeloid, Acute/metabolism
- Leukemia, Myeloid, Acute/pathology
- Mice
- Oncogene Proteins, Fusion/metabolism
- Oncogenes
- Phthalazines/pharmacology
- Phthalazines/therapeutic use
- Piperazines/pharmacology
- Piperazines/therapeutic use
- Poly(ADP-ribose) Polymerase Inhibitors/pharmacology
- Poly(ADP-ribose) Polymerase Inhibitors/therapeutic use
- Poly(ADP-ribose) Polymerases/metabolism
- Protein Kinase Inhibitors/pharmacology
- RUNX1 Translocation Partner 1 Protein
- Transcription Factors/metabolism
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Affiliation(s)
- Maria Teresa Esposito
- Leukemia and Stem Cell Biology Group, Department of Haematological Medicine, Division of Cancer Studies, King's College London, London, UK
| | - Lu Zhao
- Leukemia and Stem Cell Biology Group, Department of Haematological Medicine, Division of Cancer Studies, King's College London, London, UK
| | - Tsz Kan Fung
- Leukemia and Stem Cell Biology Group, Department of Haematological Medicine, Division of Cancer Studies, King's College London, London, UK
| | - Jayant K Rane
- Leukemia and Stem Cell Biology Group, Department of Haematological Medicine, Division of Cancer Studies, King's College London, London, UK
| | - Amanda Wilson
- Leukemia and Stem Cell Biology Group, Department of Haematological Medicine, Division of Cancer Studies, King's College London, London, UK
| | - Nadine Martin
- Cell Proliferation Group, Medical Research Council Clinical Sciences Centre, Imperial College London, London, UK
| | - Jesus Gil
- Cell Proliferation Group, Medical Research Council Clinical Sciences Centre, Imperial College London, London, UK
| | - Anskar Y Leung
- Department of Medicine, The University of Hong Kong, Hong Kong, China
| | - Alan Ashworth
- University of California, San Francisco (UCSF) Helen Diller Family Comprehensive Cancer Center, San Francisco, California, USA
| | - Chi Wai Eric So
- Leukemia and Stem Cell Biology Group, Department of Haematological Medicine, Division of Cancer Studies, King's College London, London, UK
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97
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Design, synthesis, and characterization of BRC4 mutants based on the crystal structure of BRC4-RAD51(191–220). J Mol Model 2015; 21:299. [DOI: 10.1007/s00894-015-2831-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 10/05/2015] [Indexed: 01/26/2023]
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98
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Kowalczykowski SC. An Overview of the Molecular Mechanisms of Recombinational DNA Repair. Cold Spring Harb Perspect Biol 2015; 7:a016410. [PMID: 26525148 PMCID: PMC4632670 DOI: 10.1101/cshperspect.a016410] [Citation(s) in RCA: 313] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Recombinational DNA repair is a universal aspect of DNA metabolism and is essential for genomic integrity. It is a template-directed process that uses a second chromosomal copy (sister, daughter, or homolog) to ensure proper repair of broken chromosomes. The key steps of recombination are conserved from phage through human, and an overview of those steps is provided in this review. The first step is resection by helicases and nucleases to produce single-stranded DNA (ssDNA) that defines the homologous locus. The ssDNA is a scaffold for assembly of the RecA/RAD51 filament, which promotes the homology search. On finding homology, the nucleoprotein filament catalyzes exchange of DNA strands to form a joint molecule. Recombination is controlled by regulating the fate of both RecA/RAD51 filaments and DNA pairing intermediates. Finally, intermediates that mature into Holliday structures are disjoined by either nucleolytic resolution or topological dissolution.
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Affiliation(s)
- Stephen C Kowalczykowski
- Department of Microbiology & Molecular Genetics and Department of Molecular and Cellular Biology, University of California, Davis, Davis, California 95616
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99
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Zhang F, Shi J, Bian C, Yu X. Poly(ADP-Ribose) Mediates the BRCA2-Dependent Early DNA Damage Response. Cell Rep 2015; 13:678-689. [PMID: 26489468 DOI: 10.1016/j.celrep.2015.09.040] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 07/26/2015] [Accepted: 09/14/2015] [Indexed: 01/01/2023] Open
Abstract
Breast cancer susceptibility gene 2 (BRCA2) plays a key role in DNA damage repair for maintaining genomic stability. Previous studies have shown that BRCA2 contains three tandem oligonucleotide/oligosaccharide binding folds (OB-folds) that are involved in DNA binding during DNA double-strand break repair. However, the molecular mechanism of BRCA2 in DNA damage repair remains elusive. Unexpectedly, we found that the OB-folds of BRCA2 recognize poly(ADP-ribose) (PAR) and mediate the fast recruitment of BRCA2 to DNA lesions, which is suppressed by PARP inhibitor treatment. Cancer-associated mutations in the OB-folds of BRCA2 disrupt the interaction with PAR and abolish the fast relocation of BRCA2 to DNA lesions. The quickly recruited BRCA2 is important for the early recruitment of exonuclease 1(EXO1) and is involved in DNA end resection, the first step of homologous recombination (HR). Thus, these findings uncover a molecular mechanism by which BRCA2 participates in DNA damage repair.
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Affiliation(s)
- Feng Zhang
- College of Life and Environment Sciences, Shanghai Normal University, Guilin Road 100, Shanghai 200234, China; Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA
| | - Jiazhong Shi
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA; Department of Cell Biology, the Third Military Medical University, Chongqing 400038, China
| | - Chunjing Bian
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA; Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91773, USA
| | - Xiaochun Yu
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA; Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91773, USA.
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100
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Zhao W, Vaithiyalingam S, San Filippo J, Maranon DG, Jimenez-Sainz J, Fontenay GV, Kwon Y, Leung SG, Lu L, Jensen RB, Chazin WJ, Wiese C, Sung P. Promotion of BRCA2-Dependent Homologous Recombination by DSS1 via RPA Targeting and DNA Mimicry. Mol Cell 2015; 59:176-87. [PMID: 26145171 PMCID: PMC4506714 DOI: 10.1016/j.molcel.2015.05.032] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 04/21/2015] [Accepted: 05/22/2015] [Indexed: 10/23/2022]
Abstract
The tumor suppressor BRCA2 is thought to facilitate the handoff of ssDNA from replication protein A (RPA) to the RAD51 recombinase during DNA break and replication fork repair by homologous recombination. However, we find that RPA-RAD51 exchange requires the BRCA2 partner DSS1. Biochemical, structural, and in vivo analyses reveal that DSS1 allows the BRCA2-DSS1 complex to physically and functionally interact with RPA. Mechanistically, DSS1 acts as a DNA mimic to attenuate the affinity of RPA for ssDNA. A mutation in the solvent-exposed acidic domain of DSS1 compromises the efficacy of RPA-RAD51 exchange. Thus, by targeting RPA and mimicking DNA, DSS1 functions with BRCA2 in a two-component homologous recombination mediator complex in genome maintenance and tumor suppression. Our findings may provide a paradigm for understanding the roles of DSS1 in other biological processes.
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Affiliation(s)
- Weixing Zhao
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Sivaraja Vaithiyalingam
- Departments of Biochemistry and Chemistry, and Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Joseph San Filippo
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - David G Maranon
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Judit Jimenez-Sainz
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Gerald V Fontenay
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Youngho Kwon
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Stanley G Leung
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Lucy Lu
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Ryan B Jensen
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Walter J Chazin
- Departments of Biochemistry and Chemistry, and Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA.
| | - Claudia Wiese
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA; Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA.
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