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Widaad A, Zulkipli IN, Petalcorin MIR. Anthelmintic Effect of Leucaena leucocephala Extract and Its Active Compound, Mimosine, on Vital Behavioral Activities in Caenorhabditis elegans. Molecules 2022; 27:molecules27061875. [PMID: 35335240 PMCID: PMC8950933 DOI: 10.3390/molecules27061875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/22/2022] [Accepted: 03/07/2022] [Indexed: 12/03/2022]
Abstract
Helminth infections continue to be a neglected global threat in tropical regions, and there have been growing cases of anthelmintic resistance reported towards the existing anthelmintic drugs. Thus, the search for a novel anthelmintic agent has been increasing, especially those derived from plants. Leucaena leucocephala (LL) is a leguminous plant that is known to have several pharmacological activities, including anthelmintic activity. It is widely known to contain a toxic compound called mimosine, which we believed could be a potential lead candidate that could exert a potent anthelmintic effect. Hence, this study aimed to validate the presence of mimosine in LL extract and to investigate the anthelmintic effect of LL extract and mimosine on head thrashing, egg-laying, and pharyngeal pumping activities using the animal model Caenorhabditis elegans (C. elegans). Mimosine content in LL extract was confirmed through an HPLC analysis of spiking LL extract with different mimosine concentrations, whereby an increasing trend in peak heights was observed at a retention time of 0.9 min. LL extract and mimosine caused a significant dose-dependent increase in the percentage of worm mortality, which produced LC50s of 73 mg/mL and 6.39 mg/mL, respectively. Exposure of C. elegans to different concentrations of LL extract and mimosine significantly decreased the head thrashing, egg-laying, and mean pump amplitude of pharyngeal pumping activity. We speculated that these behavioral changes are due to the inhibitory effect of LL extract and mimosine on an L-type calcium channel called EGL-19. Our findings provide evidential support for the potential of LL extract and its active compound, mimosine, as novel anthelmintic candidates. However, the underlying mechanism of the anthelmintic action has yet to be elucidated.
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2
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Shahlehi S, Petalcorin MIR. Activation of cholinergic pathway induced vasodilation in rat aorta using aqueous and methanolic leaf extracts of Gynura procumbens. Biomed Pharmacother 2021; 143:112066. [PMID: 34560550 DOI: 10.1016/j.biopha.2021.112066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 08/03/2021] [Accepted: 08/17/2021] [Indexed: 11/28/2022] Open
Abstract
Gynura procumbens (GP) is a herbal medicinal plant of South-East Asian origin, popularly recognised as 'Sambung nyawa'. The plant has been used traditionally to treat various diseases including hypertension. The anti-hypertensive activity of this plant has also been scientifically proven both in vivo and in vitro yet the investigation on its mechanisms of actions remains limited. Our previous study has demonstrated the vasodilatory action of both aqueous and methanol GP extracts possibly via activation of the cholinergic pathway and that kaempferol 3-O-rutinoside is the active ingredient responsible in mediating this effect. Hence, in this study we further confirm the involvement of the cholinergic pathway by using several pharmacological interventions, focusing on the downstream mechanism of this pathway. Our results showed that in the presence of endothelium, GP extracts induced vasodilation via activation of the muscarinic M3 receptors. However, in the absence of endothelium, GP mediated vasodilation possibly via stimulation of other muscarinic receptors and/or involvement of nicotinic receptors, a speculation that needs further investigations. GP-induced relaxation was markedly inhibited by nitric oxide (NO) blocker, L-NAME, suggesting that GP elicited ACh endothelium-dependent relaxation by producing NO in rat aortic rings. In conclusion, these data demonstrate that the vasodilatory effect of GP extracts appears to be mediated via cholinergic pathway.
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MESH Headings
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/metabolism
- Asteraceae/chemistry
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Kaempferols/isolation & purification
- Kaempferols/pharmacology
- Male
- Methanol/chemistry
- Muscarinic Agonists/isolation & purification
- Muscarinic Agonists/pharmacology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Nitric Oxide/metabolism
- Plant Extracts/isolation & purification
- Plant Extracts/pharmacology
- Plant Leaves
- Rats, Sprague-Dawley
- Receptor, Muscarinic M3/agonists
- Receptor, Muscarinic M3/metabolism
- Signal Transduction
- Solvents/chemistry
- Vasodilation/drug effects
- Vasodilator Agents/isolation & purification
- Vasodilator Agents/pharmacology
- Water/chemistry
- Rats
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Affiliation(s)
- Syahirah Shahlehi
- PAPRSB Institute of Health Sciences, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Brunei Darussalam
| | - Mark I R Petalcorin
- PAPRSB Institute of Health Sciences, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Brunei Darussalam.
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3
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Hirani N, Westenberg M, Seed PT, Petalcorin MIR, Dolphin CT. C. elegans flavin-containing monooxygenase-4 is essential for osmoregulation in hypotonic stress. Biol Open 2016; 5:668. [PMID: 27122632 PMCID: PMC4874361 DOI: 10.1242/bio.019166] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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4
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Hirani N, Westenberg M, Seed PT, Petalcorin MIR, Dolphin CT. C. elegans flavin-containing monooxygenase-4 is essential for osmoregulation in hypotonic stress. Biol Open 2016; 5:537-49. [PMID: 27010030 PMCID: PMC4874355 DOI: 10.1242/bio.017400] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Studies in Caenorhabditis elegans have revealed osmoregulatory systems engaged when worms experience hypertonic conditions, but less is known about measures employed when faced with hypotonic stress. Inactivation of fmo-4, which encodes flavin-containing monooxygenase-4, results in dramatic hypoosmotic hypersensitivity; worms are unable to prevent overwhelming water influx and swell rapidly, finally rupturing due to high internal hydrostatic pressure. fmo-4 is expressed prominently in hypodermis, duct and pore cells but is excluded from the excretory cell. Thus, FMO-4 plays a crucial osmoregulatory role by promoting clearance of excess water that enters during hypotonicity, perhaps by synthesizing an osmolyte that acts to establish an osmotic gradient from excretory cell to duct and pore cells. C. elegans FMO-4 contains a C-terminal extension conserved in all nematode FMO-4s. The coincidently numbered human FMO4 also contains an extended C-terminus with features similar to those of FMO-4. Although these shared sequence characteristics suggest potential orthology, human FMO4 was unable to rescue the fmo-4 osmoregulatory defect. Intriguingly, however, mammalian FMO4 is expressed predominantly in the kidney - an appropriate site if it too is, or once was, involved in osmoregulation.
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Affiliation(s)
- Nisha Hirani
- Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK
| | - Marcel Westenberg
- Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK
| | - Paul T Seed
- Division of Women's Health, King's College London, St Thomas' Hospital, London SE1 7EH, UK
| | - Mark I R Petalcorin
- Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK
| | - Colin T Dolphin
- Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK
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5
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Chung G, Rose AM, Petalcorin MIR, Martin JS, Kessler Z, Sanchez-Pulido L, Ponting CP, Yanowitz JL, Boulton SJ. REC-1 and HIM-5 distribute meiotic crossovers and function redundantly in meiotic double-strand break formation in Caenorhabditis elegans. Genes Dev 2015; 29:1969-79. [PMID: 26385965 PMCID: PMC4579353 DOI: 10.1101/gad.266056.115] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 08/26/2015] [Indexed: 01/07/2023]
Abstract
The Caenorhabditis elegans gene rec-1 was the first genetic locus identified in metazoa to affect the distribution of meiotic crossovers along the chromosome. We report that rec-1 encodes a distant paralog of HIM-5, which was discovered by whole-genome sequencing and confirmed by multiple genome-edited alleles. REC-1 is phosphorylated by cyclin-dependent kinase (CDK) in vitro, and mutation of the CDK consensus sites in REC-1 compromises meiotic crossover distribution in vivo. Unexpectedly, rec-1; him-5 double mutants are synthetic-lethal due to a defect in meiotic double-strand break formation. Thus, we uncovered an unexpected robustness to meiotic DSB formation and crossover positioning that is executed by HIM-5 and REC-1 and regulated by phosphorylation.
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Affiliation(s)
- George Chung
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Ann M Rose
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Mark I R Petalcorin
- DNA Damage Response Laboratory, The Francis Crick Institute, South Mimms EN3 3LD, United Kingdom; Clare Hall Laboratories, The Francis Crick Institute, South Mimms EN3 3LD, United Kingdom
| | - Julie S Martin
- DNA Damage Response Laboratory, The Francis Crick Institute, South Mimms EN3 3LD, United Kingdom; Clare Hall Laboratories, The Francis Crick Institute, South Mimms EN3 3LD, United Kingdom
| | - Zebulin Kessler
- Magee-Womens Research Institute, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA
| | - Luis Sanchez-Pulido
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Chris P Ponting
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Judith L Yanowitz
- Magee-Womens Research Institute, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA
| | - Simon J Boulton
- DNA Damage Response Laboratory, The Francis Crick Institute, South Mimms EN3 3LD, United Kingdom; Clare Hall Laboratories, The Francis Crick Institute, South Mimms EN3 3LD, United Kingdom
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6
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Ceccaldi R, Liu JC, Amunugama R, Hajdu I, Primack B, Petalcorin MIR, O'Connor KW, Konstantinopoulos PA, Elledge SJ, Boulton SJ, Yusufzai T, D'Andrea AD. Homologous-recombination-deficient tumours are dependent on Polθ-mediated repair. Nature 2015; 518:258-62. [PMID: 25642963 PMCID: PMC4415602 DOI: 10.1038/nature14184] [Citation(s) in RCA: 584] [Impact Index Per Article: 64.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 12/24/2014] [Indexed: 12/15/2022]
Abstract
Large-scale genomic studies have shown that half of epithelial ovarian cancers (EOCs) have alterations in genes regulating homologous recombination (HR) repair. Loss of HR accounts for the genomic instability of EOCs and for their cellular hyper-dependence on alternative poly-ADP ribose polymerase (PARP)-mediated DNA repair mechanisms. Previous studies have implicated the DNA polymerase θ (Polθ also known as POLQ, encoded by POLQ) in a pathway required for the repair of DNA double-strand breaks, referred to as the error-prone microhomology-mediated end-joining (MMEJ) pathway. Whether Polθ interacts with canonical DNA repair pathways to prevent genomic instability remains unknown. Here we report an inverse correlation between HR activity and Polθ expression in EOCs. Knockdown of Polθ in HR-proficient cells upregulates HR activity and RAD51 nucleofilament assembly, while knockdown of Polθ in HR-deficient EOCs enhances cell death. Consistent with these results, genetic inactivation of an HR gene (Fancd2) and Polq in mice results in embryonic lethality. Moreover, Polθ contains RAD51 binding motifs and it blocks RAD51-mediated recombination. Our results reveal a synthetic lethal relationship between the HR pathway and Polθ-mediated repair in EOCs, and identify Polθ as a novel druggable target for cancer therapy.
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Affiliation(s)
- Raphael Ceccaldi
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Jessica C Liu
- 1] Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02215, USA [2] Department of Biological Chemistry &Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02215, USA [3] Department of Molecular &Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Ravindra Amunugama
- Howard Hughes Medical Institute, Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Ildiko Hajdu
- Howard Hughes Medical Institute, Division of Genetics, Brigham and Women's Hospital, Boston, Massachusetts 02215, USA
| | - Benjamin Primack
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Mark I R Petalcorin
- DNA Damage Response Laboratory, Cancer Research UK, London Research Institute, Clare Hall, South Mimms EN6 3LD, UK
| | - Kevin W O'Connor
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Panagiotis A Konstantinopoulos
- Department of Medical Oncology, Medical Gynecologic Oncology Program, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Stephen J Elledge
- Howard Hughes Medical Institute, Division of Genetics, Brigham and Women's Hospital, Boston, Massachusetts 02215, USA
| | - Simon J Boulton
- DNA Damage Response Laboratory, Cancer Research UK, London Research Institute, Clare Hall, South Mimms EN6 3LD, UK
| | - Timur Yusufzai
- 1] Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02215, USA [2] Department of Biological Chemistry &Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Alan D D'Andrea
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02215, USA
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7
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Frizzell A, Nguyen JHG, Petalcorin MIR, Turner KD, Boulton SJ, Freudenreich CH, Lahue RS. RTEL1 inhibits trinucleotide repeat expansions and fragility. Cell Rep 2014; 6:827-35. [PMID: 24561255 PMCID: PMC5783307 DOI: 10.1016/j.celrep.2014.01.034] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 12/20/2013] [Accepted: 01/24/2014] [Indexed: 02/06/2023] Open
Abstract
Human RTEL1 is an essential, multifunctional helicase that maintains telomeres, regulates homologous recombination, and helps prevent bone marrow failure. Here, we show that RTEL1 also blocks trinucleotide repeat expansions, the causal mutation for 17 neurological diseases. Increased expansion frequencies of (CTG⋅CAG) repeats occurred in human cells following knockdown of RTEL1, but not the alternative helicase Fbh1, and purified RTEL1 efficiently unwound triplet repeat hairpins in vitro. The expansion-blocking activity of RTEL1 also required Rad18 and HLTF, homologs of yeast Rad18 and Rad5. These findings are reminiscent of budding yeast Srs2, which inhibits expansions, unwinds hairpins, and prevents triplet-repeat-induced chromosome fragility. Accordingly, we found expansions and fragility were suppressed in yeast srs2 mutants expressing RTEL1, but not Fbh1. We propose that RTEL1 serves as a human analog of Srs2 to inhibit (CTG⋅CAG) repeat expansions and fragility, likely by unwinding problematic hairpins.
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Affiliation(s)
- Aisling Frizzell
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Newcastle Road, Galway, Ireland
| | | | - Mark I R Petalcorin
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, Clare Hall, South Mimms EN6 3LD, UK
| | - Katherine D Turner
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Newcastle Road, Galway, Ireland; NCBES Galway Neuroscience Centre, National University of Ireland Galway, Newcastle Road, Galway, Ireland
| | - Simon J Boulton
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, Clare Hall, South Mimms EN6 3LD, UK
| | | | - Robert S Lahue
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Newcastle Road, Galway, Ireland; NCBES Galway Neuroscience Centre, National University of Ireland Galway, Newcastle Road, Galway, Ireland.
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8
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Vannier JB, Sandhu S, Petalcorin MIR, Wu X, Nabi Z, Ding H, Boulton SJ. RTEL1 is a replisome-associated helicase that promotes telomere and genome-wide replication. Science 2013; 342:239-42. [PMID: 24115439 DOI: 10.1126/science.1241779] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Regulator of telomere length 1 (RTEL1) is an essential DNA helicase that disassembles telomere loops (T loops) and suppresses telomere fragility to maintain the integrity of chromosome ends. We established that RTEL1 also associates with the replisome through binding to proliferating cell nuclear antigen (PCNA). Mouse cells disrupted for the RTEL1-PCNA interaction (PIP mutant) exhibited accelerated senescence, replication fork instability, reduced replication fork extension rates, and increased origin usage. Although T-loop disassembly at telomeres was unaffected in the mutant cells, telomere replication was compromised, leading to fragile sites at telomeres. RTEL1-PIP mutant mice were viable, but loss of the RTEL1-PCNA interaction accelerated the onset of tumorigenesis in p53-deficient mice. We propose that RTEL1 plays a critical role in both telomere and genome-wide replication, which is crucial for genetic stability and tumor avoidance.
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Affiliation(s)
- Jean-Baptiste Vannier
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, Clare Hall, South Mimms, UK
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9
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O'Neil NJ, Martin JS, Youds JL, Ward JD, Petalcorin MIR, Rose AM, Boulton SJ. Joint molecule resolution requires the redundant activities of MUS-81 and XPF-1 during Caenorhabditis elegans meiosis. PLoS Genet 2013; 9:e1003582. [PMID: 23874209 PMCID: PMC3715453 DOI: 10.1371/journal.pgen.1003582] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Accepted: 05/07/2013] [Indexed: 11/29/2022] Open
Abstract
The generation and resolution of joint molecule recombination intermediates is required to ensure bipolar chromosome segregation during meiosis. During wild type meiosis in Caenorhabditis elegans, SPO-11-generated double stranded breaks are resolved to generate a single crossover per bivalent and the remaining recombination intermediates are resolved as noncrossovers. We discovered that early recombination intermediates are limited by the C. elegans BLM ortholog, HIM-6, and in the absence of HIM-6 by the structure specific endonuclease MUS-81. In the absence of both MUS-81 and HIM-6, recombination intermediates persist, leading to chromosome breakage at diakinesis and inviable embryos. MUS-81 has an additional role in resolving late recombination intermediates in C. elegans. mus-81 mutants exhibited reduced crossover recombination frequencies suggesting that MUS-81 is required to generate a subset of meiotic crossovers. Similarly, the Mus81-related endonuclease XPF-1 is also required for a subset of meiotic crossovers. Although C. elegans gen-1 mutants have no detectable meiotic defect either alone or in combination with him-6, mus-81 or xpf-1 mutations, mus-81;xpf-1 double mutants are synthetic lethal. While mus-81;xpf-1 double mutants are proficient for the processing of early recombination intermediates, they exhibit defects in the post-pachytene chromosome reorganization and the asymmetric disassembly of the synaptonemal complex, presumably triggered by crossovers or crossover precursors. Consistent with a defect in resolving late recombination intermediates, mus-81; xpf-1 diakinetic bivalents are aberrant with fine DNA bridges visible between two distinct DAPI staining bodies. We were able to suppress the aberrant bivalent phenotype by microinjection of activated human GEN1 protein, which can cleave Holliday junctions, suggesting that the DNA bridges in mus-81; xpf-1 diakinetic oocytes are unresolved Holliday junctions. We propose that the MUS-81 and XPF-1 endonucleases act redundantly to process late recombination intermediates to form crossovers during C. elegans meiosis.
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Affiliation(s)
- Nigel J. O'Neil
- Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Julie S. Martin
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, South Mimms, United Kingdom
| | - Jillian L. Youds
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, South Mimms, United Kingdom
| | - Jordan D. Ward
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, South Mimms, United Kingdom
| | - Mark I. R. Petalcorin
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, South Mimms, United Kingdom
| | - Anne M. Rose
- Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Simon J. Boulton
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, South Mimms, United Kingdom
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10
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Vannier JB, Pavicic-Kaltenbrunner V, Petalcorin MIR, Ding H, Boulton SJ. RTEL1 dismantles T loops and counteracts telomeric G4-DNA to maintain telomere integrity. Cell 2012; 149:795-806. [PMID: 22579284 DOI: 10.1016/j.cell.2012.03.030] [Citation(s) in RCA: 343] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 01/11/2012] [Accepted: 03/02/2012] [Indexed: 11/19/2022]
Abstract
T loops and telomeric G-quadruplex (G4) DNA structures pose a potential threat to genome stability and must be dismantled to permit efficient telomere replication. Here we implicate the helicase RTEL1 in the removal of telomeric DNA secondary structures, which is essential for preventing telomere fragility and loss. In the absence of RTEL1, T loops are inappropriately resolved by the SLX4 nuclease complex, resulting in loss of the telomere as a circle. Depleting SLX4 or blocking DNA replication abolished telomere circles (TCs) and rescued telomere loss in RTEL1(-/-) cells but failed to suppress telomere fragility. Conversely, stabilization of telomeric G4-DNA or loss of BLM dramatically enhanced telomere fragility in RTEL1-deficient cells but had no impact on TC formation or telomere loss. We propose that RTEL1 performs two distinct functions at telomeres: it disassembles T loops and also counteracts telomeric G4-DNA structures, which together ensure the dynamics and stability of the telomere.
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Affiliation(s)
- Jean-Baptiste Vannier
- DNA Damage Response laboratory, London Research Institute, Cancer Research UK, Clare Hall, South Mimms, UK
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11
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Moldovan GL, Dejsuphong D, Petalcorin MIR, Hofmann K, Takeda S, Boulton SJ, D’Andrea AD. Inhibition of homologous recombination by the PCNA-interacting protein PARI. Mol Cell 2012; 45:75-86. [PMID: 22153967 PMCID: PMC3267324 DOI: 10.1016/j.molcel.2011.11.010] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 08/12/2011] [Accepted: 11/04/2011] [Indexed: 12/23/2022]
Abstract
Inappropriate homologous recombination (HR) causes genomic instability and cancer. In yeast, the UvrD family helicase Srs2 is recruited to sites of DNA replication by SUMO-modified PCNA, where it acts to restrict HR by disassembling toxic RAD51 nucleofilaments. How human cells control recombination at replication forks is unknown. Here, we report that the protein PARI, containing a UvrD-like helicase domain, is a PCNA-interacting partner required for preservation of genome stability in human and DT40 chicken cells. Using cell-based and biochemical assays, we show that PARI restricts unscheduled recombination by interfering with the formation of RAD51-DNA HR structures. Finally, we show that PARI knockdown suppresses the genomic instability of Fanconi Anemia/BRCA pathway-deficient cells. Thus, we propose that PARI is a long sought-after factor that suppresses inappropriate recombination events at mammalian replication forks.
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Affiliation(s)
- George-Lucian Moldovan
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street, Boston MA 02215, USA
| | - Donniphat Dejsuphong
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street, Boston MA 02215, USA
| | - Mark I. R. Petalcorin
- DNA Damage Response Laboratory, Cancer Research UK, London Research Institute, Clare Hall, Blanche Lane, South Mimms EN6 3LD, UK
| | - Kay Hofmann
- Bioinformatics Group, Miltenyi Biotec GmbH, Friedrich-Ebert-Strasse 68, 51429 Bergisch-Gladbach, Germany
| | - Shunichi Takeda
- Department of Radiation Genetics, Kyoto University Graduate School of Medicine, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Simon J. Boulton
- DNA Damage Response Laboratory, Cancer Research UK, London Research Institute, Clare Hall, Blanche Lane, South Mimms EN6 3LD, UK
| | - Alan D. D’Andrea
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street, Boston MA 02215, USA
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12
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Ward JD, Muzzini DM, Petalcorin MIR, Martinez-Perez E, Martin JS, Plevani P, Cassata G, Marini F, Boulton SJ. Overlapping mechanisms promote postsynaptic RAD-51 filament disassembly during meiotic double-strand break repair. Mol Cell 2010; 37:259-72. [PMID: 20122407 DOI: 10.1016/j.molcel.2009.12.026] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 09/28/2009] [Accepted: 10/30/2009] [Indexed: 12/17/2022]
Abstract
Homologous recombination (HR) is essential for repair of meiotic DNA double-strand breaks (DSBs). Although the mechanisms of RAD-51-DNA filament assembly and strand exchange are well characterized, the subsequent steps of HR are less well defined. Here, we describe a synthetic lethal interaction between the C. elegans helicase helq-1 and RAD-51 paralog rfs-1, which results in a block to meiotic DSB repair after strand invasion. Whereas RAD-51-ssDNA filaments assemble at meiotic DSBs with normal kinetics in helq-1, rfs-1 double mutants, persistence of RAD-51 foci and genetic interactions with rtel-1 suggest a failure to disassemble RAD-51 from strand invasion intermediates. Indeed, purified HELQ-1 and RFS-1 independently bind to and promote the disassembly of RAD-51 from double-stranded, but not single-stranded, DNA filaments via distinct mechanisms in vitro. These results indicate that two compensating activities are required to promote postsynaptic RAD-51 filament disassembly, which are collectively essential for completion of meiotic DSB repair.
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Affiliation(s)
- Jordan D Ward
- DNA Damage Response Laboratory, Cancer Research UK, Clare Hall Laboratories, South Mimms EN6 3LD, UK
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Petalcorin MIR, Galkin VE, Yu X, Egelman EH, Boulton SJ. Stabilization of RAD-51-DNA filaments via an interaction domain in Caenorhabditis elegans BRCA2. Proc Natl Acad Sci U S A 2007; 104:8299-304. [PMID: 17483448 PMCID: PMC1895944 DOI: 10.1073/pnas.0702805104] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mutations in BRCA2 predispose individuals to breast cancer, a consequence of the role of BRCA2 in DNA repair. Human BRCA2 interacts with the recombinase RAD51 via eight BRC repeats. Controversy has existed, however, about whether the BRC interactions are primarily with RAD51 monomers or with the RAD51-DNA helical polymer, and whether there is a single interaction or multiple ones. We show here that the single BRC motif in the Caenorhabditis elegans BRCA2 homolog, CeBRC-2, contains two different RAD-51-binding regions. One of these regions binds only weakly to RAD-51-DNA filaments but strongly to RAD-51 alone and corresponds to the part of human BRC4 crystallized with RAD51. Injection of a peptide corresponding to this region into worms inhibits the normal formation of RAD-51 foci in response to ionizing radiation (IR). Conversely, peptides corresponding to the second region bind strongly to RAD-51-DNA filaments but do not bind to RAD-51 alone. Three-dimensional reconstructions from electron micrographs show that this peptide binds to the RAD-51 N-terminal domain, which has been shown to have a regulatory function. Injection of this peptide into worms before IR leads to a dramatic increase and persistence of IR-induced RAD-51 foci. This peptide also inhibits the RAD-51 ATPase activity, required for filament depolymerization. These results support a model where an interaction with RAD-51 alone is likely involved in filament nucleation, whereas a second independent interaction is involved in stabilization of RAD-51 filaments by BRCA2. The multiple interactions between BRCA2-like molecules and RAD51 provide insights into why mutations in BRCA2 lead to cancer.
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Affiliation(s)
- Mark I. R. Petalcorin
- *Clare Hall Laboratories, London Research Institute, Cancer Research UK, South Mimms, Hertfordshire EN6 3LD, United Kingdom; and
| | - Vitold E. Galkin
- Department of Biochemistry and Molecular Genetics, Box 800733, University of Virginia, Charlottesville, VA 22908
| | - Xiong Yu
- Department of Biochemistry and Molecular Genetics, Box 800733, University of Virginia, Charlottesville, VA 22908
| | - Edward H. Egelman
- Department of Biochemistry and Molecular Genetics, Box 800733, University of Virginia, Charlottesville, VA 22908
- To whom correspondence should be addressed. E-mail:
| | - Simon J. Boulton
- *Clare Hall Laboratories, London Research Institute, Cancer Research UK, South Mimms, Hertfordshire EN6 3LD, United Kingdom; and
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Petalcorin MIR, Martin JS, Boulton SJ. Genome-wide RNAi to identify genes that confer synthetic lethality with BRCA1. Breast Cancer Res 2006. [PMCID: PMC3300245 DOI: 10.1186/bcr1553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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15
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Petalcorin MIR, Sandall J, Wigley DB, Boulton SJ. CeBRC-2 stimulates D-loop formation by RAD-51 and promotes DNA single-strand annealing. J Mol Biol 2006; 361:231-42. [PMID: 16843491 DOI: 10.1016/j.jmb.2006.06.020] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Revised: 06/09/2006] [Accepted: 06/12/2006] [Indexed: 01/09/2023]
Abstract
The BRCA2 tumour suppressor regulates the RAD-51 recombinase during double-strand break (DSB) repair by homologous recombination (HR) but how BRCA2 executes its functions is not well understood. We previously described a functional homologue of BRCA2 in Caenorhabditis elegans (CeBRC-2) that binds preferentially to single-stranded DNA via an OB-fold domain and associates directly with RAD-51 via a single BRC domain. Consistent with a direct role in HR, Cebrc-2 mutants are defective for repair of meiotic and radiation-induced DSBs due to an inability to regulate RAD-51. Here, we explore the function of CeBRC-2 in HR processes using purified proteins. We show that CeBRC-2 stimulates RAD-51-mediated D-loop formation and reduces the rate of ATP hydrolysis catalysed by RAD-51. These functions of CeBRC-2 are dependent upon direct association with RAD-51 via its BRC motif and on its DNA-binding activity, as point mutations in the BRC domain that abolish RAD-51 binding or the BRC domain of CeBRC-2 alone, lacking the DNA-binding domain, fail to stimulate RAD-51-mediated D-loop formation and do not reduce the rate of ATP hydrolysis by RAD-51. Phenotypic comparison of Cebrc-2 and rad-51 mutants also revealed a role for CeBRC-2 in an error-prone DSB repair pathway independent of rad-51 and non-homologous end joining, raising the possibility that CeBRC-2 may have replaced the role of vertebrate Rad52 in DNA single-strand annealing (SSA), which is missing from C. elegans. Indeed, we show here that CeBRC-2 mediates SSA of RPA-oligonucleotide complexes similar to Rad52. These results reveal RAD-51-dependent and -independent functions of CeBRC-2 that provide an explanation for the difference in DNA repair defects observed in Cebrc-2 and rad-51 mutants, and define mechanistic roles for CeBRC-2 in HR and in the SSA pathway for DSB repair.
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Affiliation(s)
- Mark I R Petalcorin
- Molecular Enzymology Laboratory, Cancer Research UK, The London Research Institute, Clare Hall Laboratories, South Mimms, EN6 3LD, UK
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16
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Polanowska J, Martin JS, Garcia-Muse T, Petalcorin MIR, Boulton SJ. A conserved pathway to activate BRCA1-dependent ubiquitylation at DNA damage sites. EMBO J 2006; 25:2178-88. [PMID: 16628214 PMCID: PMC1462971 DOI: 10.1038/sj.emboj.7601102] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2005] [Accepted: 03/28/2006] [Indexed: 11/09/2022] Open
Abstract
The BRCA1 tumour suppressor and its heterodimeric partner BARD1 constitute an E3-ubiquitin (Ub) ligase and function in DNA repair by unknown mechanisms. We show here that the Caenorhabditis elegans BRCA1/BARD1 (CeBCD) complex possesses an E3-Ub ligase responsible for ubiquitylation at DNA damage sites following ionizing radiation (IR). The DNA damage checkpoint promotes the association of the CeBCD complex with E2-Ub conjugating enzyme, Ubc5(LET-70), leading to the formation of an active E3-Ub ligase on chromatin following IR. Correspondingly, defects in Ubc5(let-70) or the DNA damage checkpoint genes atl-1 or mre-11 abolish CeBCD-dependent ubiquitylation in vivo. Extending these findings to human cells reveals a requirement for UbcH5c, the MRN complex, gamma-H2AX and a co-dependence for ATM and ATR kinases for BRCA1-dependent ubiquitylation at DNA damage sites. Furthermore, we demonstrate that the DNA damage checkpoint promotes the association between BRCA1 and UbcH5c to form an active E3-Ub ligase on chromatin after IR. These data reveal that BRCA1-dependent ubiquitylation is activated at sites of DNA repair by the checkpoint as part of a conserved DNA damage response.
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Affiliation(s)
- Jolanta Polanowska
- DNA Damage Response Laboratory, Cancer Research UK, London Research Institute, Clare Hall Laboratories, South Mimms, UK
| | - Julie S Martin
- DNA Damage Response Laboratory, Cancer Research UK, London Research Institute, Clare Hall Laboratories, South Mimms, UK
| | - Tatiana Garcia-Muse
- DNA Damage Response Laboratory, Cancer Research UK, London Research Institute, Clare Hall Laboratories, South Mimms, UK
| | - Mark I R Petalcorin
- DNA Damage Response Laboratory, Cancer Research UK, London Research Institute, Clare Hall Laboratories, South Mimms, UK
| | - Simon J Boulton
- DNA Damage Response Laboratory, Cancer Research UK, London Research Institute, Clare Hall Laboratories, South Mimms, UK
- DNA Damage Response Laboratory, Cancer Research UK, London Research Institute, Clare Hall Laboratories, Blanche Lane, UK-South Mimms, Herts EN6 3LD, UK. Tel.: +44 1707 625774; Fax:+44 2072 693801; E-mail:
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Martin JS, Winkelmann N, Petalcorin MIR, McIlwraith MJ, Boulton SJ. RAD-51-dependent and -independent roles of a Caenorhabditis elegans BRCA2-related protein during DNA double-strand break repair. Mol Cell Biol 2005; 25:3127-39. [PMID: 15798199 PMCID: PMC1069622 DOI: 10.1128/mcb.25.8.3127-3139.2005] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The BRCA2 tumor suppressor is implicated in DNA double-strand break (DSB) repair by homologous recombination (HR), where it regulates the RAD51 recombinase. We describe a BRCA2-related protein of Caenorhabditis elegans (CeBRC-2) that interacts directly with RAD-51 via a single BRC motif and that binds preferentially to single-stranded DNA through an oligonucleotide-oligosaccharide binding fold. Cebrc-2 mutants fail to repair meiotic or radiation-induced DSBs by HR due to inefficient RAD-51 nuclear localization and a failure to target RAD-51 to sites of DSBs. Genetic and cytological comparisons of Cebrc-2 and rad-51 mutants revealed fundamental phenotypic differences that suggest a role for Cebrc-2 in promoting the use of an alternative repair pathway in the absence of rad-51 and independent of nonhomologous end joining (NHEJ). Unlike rad-51 mutants, Cebrc-2 mutants also accumulate RPA-1 at DSBs, and abnormal chromosome aggregates that arise during the meiotic prophase can be rescued by blocking the NHEJ pathway. CeBRC-2 also forms foci in response to DNA damage and can do so independently of rad-51. Thus, CeBRC-2 not only regulates RAD-51 during HR but can also function independently of rad-51 in DSB repair processes.
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Affiliation(s)
- Julie S Martin
- Clare Hall Laboratories, London Research Institute, Cancer Research UK, Blanche Ln., South Mimms, Hertfordshire EN6 3LD, United Kingdom
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Petalcorin MIR, Joshua GW, Agapow PM, Dolphin CT. The fmo genes of Caenorhabditis elegans and C. briggsae: characterisation, gene expression and comparative genomic analysis. Gene 2004; 346:83-96. [PMID: 15716098 DOI: 10.1016/j.gene.2004.09.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2004] [Revised: 08/18/2004] [Accepted: 09/28/2004] [Indexed: 10/26/2022]
Abstract
The flavin-containing monooxygenase (FMO) gene family is conserved and ancient with representatives present in almost all phyla so far examined. The genes encode FAD-, NADP- and O(2)-dependent enzymes that catalyse oxygenation of soft-nucleophilic heteroatom centres in a range of substrates. Although usually classified as xenobiotic-metabolising enzymes, examples of FMOs exist that have evolved to metabolise specific endogenous substrates as part of a discrete physiological process. The genome of Caenorhabditis elegans contains five predicted genes encoding putative homologs of mammalian FMOs, K08C7.2, K08C7.5, Y39A1A.19, F53F4.5 and H24K24.5, which we have named fmo and numbered fmo-1 to fmo-5, respectively. As a first step towards determining their functional role(s), we have experimentally characterised these C. elegans fmo genes including analysing reporter gene expression patterns and RNAi phenotypes. Two major gene expression patterns were observed, either intestinal or hypodermal, but no gross RNAi phenotypes were found possibly due to functional redundancy. The internal structures of fmo-2, fmo-3 and fmo-4 have been compared with orthologs identified in the related nematode C. briggsae. For each orthologous pair, a global comparison of the paired upstream intergenic regions was performed and a number of conserved noncoding sequences, which may represent potential cis-regulatory elements, identified. Phylogenetic analysis reveals that several of the fmo homologs are the result of gene duplication along the lineage leading to the nematodes.
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Affiliation(s)
- Mark I R Petalcorin
- Section of Molecular Genetics, Pharmaceutical Science Research Division, Franklin-Wilkins Building, 150 Stamford Street, King's College London, London SE1 9NN, UK
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