51
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Family-Specific Variants and the Limits of Human Genetics. Trends Mol Med 2016; 22:925-934. [PMID: 27742414 DOI: 10.1016/j.molmed.2016.09.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 09/10/2016] [Accepted: 09/13/2016] [Indexed: 01/28/2023]
Abstract
Every single-nucleotide change compatible with life is present in the human population today. Understanding these rare human variants defines an extraordinary challenge for genetics and medicine. The new clinical practice of sequencing many genes for hereditary cancer risk has illustrated the utility of clinical next-generation sequencing in adults, identifying more medically actionable variants than single-gene testing. However, it has also revealed a linear relationship between the length of DNA evaluated and the number of rare 'variants of uncertain significance' reported. We propose that careful approaches to phenotype-genotype inference, distinguishing between diagnostic and screening intent, in conjunction with expanded use of family-scale genetics studies as a source of information on family-specific variants, will reduce variants of uncertain significance reported to patients.
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52
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Fradet-Turcotte A, Sitz J, Grapton D, Orthwein A. BRCA2 functions: from DNA repair to replication fork stabilization. Endocr Relat Cancer 2016; 23:T1-T17. [PMID: 27530658 DOI: 10.1530/erc-16-0297] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 08/16/2016] [Indexed: 12/12/2022]
Abstract
Maintaining genomic integrity is essential to preserve normal cellular physiology and to prevent the emergence of several human pathologies including cancer. The breast cancer susceptibility gene 2 (BRCA2, also known as the Fanconi anemia (FA) complementation group D1 (FANCD1)) is a potent tumor suppressor that has been extensively studied in DNA double-stranded break (DSB) repair by homologous recombination (HR). However, BRCA2 participates in numerous other processes central to maintaining genome stability, including DNA replication, telomere homeostasis and cell cycle progression. Consequently, inherited mutations in BRCA2 are associated with an increased risk of breast, ovarian and pancreatic cancers. Furthermore, bi-allelic mutations in BRCA2 are linked to FA, a rare chromosome instability syndrome characterized by aplastic anemia in children as well as susceptibility to leukemia and cancer. Here, we discuss the recent developments underlying the functions of BRCA2 in the maintenance of genomic integrity. The current model places BRCA2 as a central regulator of genome stability by repairing DSBs and limiting replication stress. These findings have direct implications for the development of novel anticancer therapeutic approaches.
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Affiliation(s)
- Amélie Fradet-Turcotte
- Laval University Cancer Research CenterCHU de Québec Research Center - Université Laval, Hôtel-Dieu de Québec, Oncology Axis, Quebec City, Canada
| | - Justine Sitz
- Laval University Cancer Research CenterCHU de Québec Research Center - Université Laval, Hôtel-Dieu de Québec, Oncology Axis, Quebec City, Canada
| | - Damien Grapton
- Lady Davis Institute for Medical ResearchSegal Cancer Centre, Jewish General Hospital, Montreal, Canada
| | - Alexandre Orthwein
- Lady Davis Institute for Medical ResearchSegal Cancer Centre, Jewish General Hospital, Montreal, Canada Department of OncologyMcGill University, Montreal, Canada
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53
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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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54
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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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55
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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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56
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Browning CL, Qin Q, Kelly DF, Prakash R, Vanoli F, Jasin M, Wise JP. Prolonged Particulate Hexavalent Chromium Exposure Suppresses Homologous Recombination Repair in Human Lung Cells. Toxicol Sci 2016; 153:70-8. [PMID: 27449664 DOI: 10.1093/toxsci/kfw103] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Genomic instability is one of the primary models of carcinogenesis and a feature of almost all cancers. Homologous recombination (HR) repair protects against genomic instability by maintaining high genomic fidelity during the repair of DNA double strand breaks. The defining step of HR repair is the formation of the Rad51 nucleofilament, which facilitates the search for a homologous sequence and invasion of the template DNA strand. Particulate hexavalent chromium (Cr(VI)), a human lung carcinogen, induces DNA double strand breaks and chromosome instability. Since the loss of HR repair increases Cr(VI)-induced chromosome instability, we investigated the effect of extended Cr(VI) exposure on HR repair. We show acute (24 h) Cr(VI) exposure induces a normal HR repair response. In contrast, prolonged (120 h) exposure to particulate Cr(VI) inhibited HR repair and Rad51 nucleofilament formation. Prolonged Cr(VI) exposure had a profound effect on Rad51, evidenced by reduced protein levels and Rad51 mislocalization to the cytoplasm. The response of proteins involved in Rad51 nuclear import and nucleofilament formation displayed varying responses to prolonged Cr(VI) exposure. BRCA2 formed nuclear foci after prolonged Cr(VI) exposure, while Rad51C foci formation was suppressed. These results suggest that particulate Cr(VI), a major chemical carcinogen, inhibits HR repair by targeting Rad51, causing DNA double strand breaks to be repaired by a low fidelity, Rad51-independent repair pathway. These results further enhance our understanding of the underlying mechanism of Cr(VI)-induced chromosome instability and thus, carcinogenesis.
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Affiliation(s)
- Cynthia L Browning
- *Wise Laboratory of Environmental and Genetic Toxicology, Portland, Maine 04104 Graduate School of Biomedical Science and Engineering, University of Maine, Orono, Maine 04469
| | - Qin Qin
- *Wise Laboratory of Environmental and Genetic Toxicology, Portland, Maine 04104 Virginia Tech Carilion Research Institute, Roanoke, Virginia 24016
| | - Deborah F Kelly
- Virginia Tech Carilion Research Institute, Roanoke, Virginia 24016
| | - Rohit Prakash
- Memorial Sloan Kettering Cancer Center, New York 10065, New York
| | - Fabio Vanoli
- Memorial Sloan Kettering Cancer Center, New York 10065, New York
| | - Maria Jasin
- Memorial Sloan Kettering Cancer Center, New York 10065, New York
| | - John Pierce Wise
- *Wise Laboratory of Environmental and Genetic Toxicology, Portland, Maine 04104 Graduate School of Biomedical Science and Engineering, University of Maine, Orono, Maine 04469
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57
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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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58
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Thorgeirsson T, Jordahl KM, Flavin R, Epstein MM, Fiorentino M, Andersson SO, Andren O, Rider JR, Mosquera JM, Ingoldsby H, Fall K, Tryggvadottir L, Mucci LA. Intracellular location of BRCA2 protein expression and prostate cancer progression in the Swedish Watchful Waiting Cohort. Carcinogenesis 2016; 37:262-8. [PMID: 26775038 DOI: 10.1093/carcin/bgw001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 01/02/2016] [Indexed: 01/07/2023] Open
Abstract
Prostate cancer patients with inherited BRCA2 mutations have a survival disadvantage. However, it is unknown whether progression is associated with BRCA2 protein expression in diagnostic prostate cancer tissue, among men without inherited mutations. We conducted a nested case-control study within the Swedish Watchful Waiting cohort. The case group included all 71 patients who died from prostate cancer within 5 years from diagnosis and controls were all patients (n = 165) who lived at least 7 years after diagnosis. Tissue microarrays were stained using antibodies for C- and N-terminal domains of the BRCA2 protein. Location (nuclear, cytoplasmic and membranous) and magnitude (intensity and percentage) of expression were assessed. Logistic regression models produced odds ratios (OR) and 95% confidence intervals (CI) adjusted for age, year of diagnosis and Gleason score. Positive BRCA2 staining at the cell membrane was associated with reduced risk of death within 5 years (N-terminal: OR = 0.47, 95% CI = 0.21-1.04, P = 0.06; C-terminal: OR = 0.41, 95% CI = 0.18-0.91, P = 0.03) and low Gleason scores (P = 0.006). Positive cytoplasmic C-terminal staining was associated with higher Gleason scores and increased lethality (OR = 3.61, 95% CI = 1.61-8.07, P = 0.002). BRCA2 protein expression at the cell membrane and lack of C-terminal expression in the cytoplasm were associated with a reduced risk of rapidly fatal prostate cancer. BRCA2 protein expression in prostate cancer tissue may have independent prognostic value. The potential biological significance of BRCA2 expression at the cell membrane warrants further investigation.
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Affiliation(s)
- Tryggvi Thorgeirsson
- Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA, Public Health Sciences, University of Iceland, 101 Reykjavik, Iceland
| | - Kristina M Jordahl
- Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA
| | - Richard Flavin
- Center for Molecular Oncologic Pathology, Dana Farber Cancer Institute, Boston, MA 02215, USA, Department of Histopathology, St. James's Hospital Dublin, Dublin 8, Ireland, Trinity College Dublin, Dublin, Ireland
| | - Mara Meyer Epstein
- Department of Medicine and the Meyers Primary Care Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Michelangelo Fiorentino
- Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA, "F. Addarii" Institute of Oncology and Transplantation Pathology, S.Orsola-Malpighi Hospital, Bologna University, 40126 Bologna, Italy
| | - Swen-Olof Andersson
- Department of Urology, Faculty of Medicine and Health, Örebro University, SE 701 82 Örebro, Sweden
| | - Ove Andren
- Department of Urology, Faculty of Medicine and Health, Örebro University, SE 701 82 Örebro, Sweden
| | - Jennifer R Rider
- Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA
| | - Juan Miguel Mosquera
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY 10065, USA, Institute for Precision Medicine of Weill Cornell Medical College and New York Presbyterian, New York, NY 10065, USA
| | - Helen Ingoldsby
- National University of Ireland, Shantalla Road, Galway, Ireland
| | - Katja Fall
- Clinical Epidemiology and Biostatistics, Faculty of Medicine and Health, Örebro University, SE 701 82 Örebro, Sweden
| | - Laufey Tryggvadottir
- Icelandic Cancer Registry, 105 Reykjavik, Iceland and Faculty of Medicine, University of Iceland, 101 Reykjavik, Iceland
| | - Lorelei A Mucci
- Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA, Public Health Sciences, University of Iceland, 101 Reykjavik, Iceland
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59
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A calreticulin-dependent nuclear export signal is involved in the regulation of liver receptor homologue-1 protein folding. Biochem J 2015; 471:199-209. [DOI: 10.1042/bj20150252] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 08/12/2015] [Indexed: 12/23/2022]
Abstract
LRH-1 (liver receptor homologue-1) contained a calreticulin-dependent NES (nuclear export signal) that regulate shutting, protein folding and transactivity.
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60
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Dickmanns A, Monecke T, Ficner R. Structural Basis of Targeting the Exportin CRM1 in Cancer. Cells 2015; 4:538-68. [PMID: 26402707 PMCID: PMC4588050 DOI: 10.3390/cells4030538] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 09/07/2015] [Accepted: 09/11/2015] [Indexed: 12/19/2022] Open
Abstract
Recent studies have demonstrated the interference of nucleocytoplasmic trafficking with the establishment and maintenance of various cancers. Nucleocytoplasmic transport is highly regulated and coordinated, involving different nuclear transport factors or receptors, importins and exportins, that mediate cargo transport from the cytoplasm into the nucleus or the other way round, respectively. The exportin CRM1 (Chromosome region maintenance 1) exports a plethora of different protein cargoes and ribonucleoprotein complexes. Structural and biochemical analyses have enabled the deduction of individual steps of the CRM1 transport cycle. In addition, CRM1 turned out to be a valid target for anticancer drugs as it exports numerous proto-oncoproteins and tumor suppressors. Clearly, detailed understanding of the flexibility, regulatory features and cooperative binding properties of CRM1 for Ran and cargo is a prerequisite for the design of highly effective drugs. The first compound found to inhibit CRM1-dependent nuclear export was the natural drug Leptomycin B (LMB), which blocks export by competitively interacting with a highly conserved cleft on CRM1 required for nuclear export signal recognition. Clinical studies revealed serious side effects of LMB, leading to a search for alternative natural and synthetic drugs and hence a multitude of novel therapeutics. The present review examines recent progress in understanding the binding mode of natural and synthetic compounds and their inhibitory effects.
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Affiliation(s)
- Achim Dickmanns
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, Göttingen 37077, Germany.
| | - Thomas Monecke
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, Göttingen 37077, Germany.
| | - Ralf Ficner
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, Göttingen 37077, Germany.
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61
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de Sena-Tomás C, Sutherland JH, Milisavljevic M, Nikolic DB, Pérez-Martín J, Kojic M, Holloman WK. LAMMER kinase contributes to genome stability in Ustilago maydis. DNA Repair (Amst) 2015; 33:70-7. [PMID: 26176563 PMCID: PMC4526389 DOI: 10.1016/j.dnarep.2015.05.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 05/20/2015] [Indexed: 11/25/2022]
Abstract
Here we report identification of the lkh1 gene encoding a LAMMER kinase homolog (Lkh1) from a screen for DNA repair-deficient mutants in Ustilago maydis. The mutant allele isolated results from a mutation at glutamine codon 488 to a stop codon that would be predicted to lead to truncation of the carboxy-terminal kinase domain of the protein. This mutant (lkh1(Q488*)) is highly sensitive to ultraviolet light, methyl methanesulfonate, and hydroxyurea. In contrast, a null mutant (lkh1Δ) deleted of the entire lkh1 gene has a less severe phenotype. No epistasis was observed when an lkh1(Q488*)rad51Δ double mutant was tested for genotoxin sensitivity. However, overexpressing the gene for Rad51, its regulator Brh2, or the Brh2 regulator Dss1 partially restored genotoxin resistance of the lkh1Δ and lkh1(Q488*) mutants. Deletion of lkh1 in a chk1Δ mutant enabled these double mutant cells to continue to cycle when challenged with hydroxyurea. lkh1Δ and lkh1(Q488*) mutants were able to complete the meiotic process but exhibited reduced heteroallelic recombination and aberrant chromosome segregation. The observations suggest that Lkh1 serves in some aspect of cell cycle regulation after DNA damage or replication stress and that it also contributes to proper chromosome segregation in meiosis.
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Affiliation(s)
- Carmen de Sena-Tomás
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Jeanette H Sutherland
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Mira Milisavljevic
- Laboratory for Plant Molecular Biology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Serbia
| | - Dragana B Nikolic
- Laboratory for Plant Molecular Biology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Serbia
| | - José Pérez-Martín
- Institute of Functional Biology and Genomics, Consejo Superior de Investigaciones Científicas CSIC, Salamanca, Spain
| | - Milorad Kojic
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA; Laboratory for Plant Molecular Biology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Serbia
| | - William K Holloman
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA.
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62
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Taylor MRG, Špírek M, Chaurasiya KR, Ward JD, Carzaniga R, Yu X, Egelman EH, Collinson LM, Rueda D, Krejci L, Boulton SJ. Rad51 Paralogs Remodel Pre-synaptic Rad51 Filaments to Stimulate Homologous Recombination. Cell 2015; 162:271-286. [PMID: 26186187 PMCID: PMC4518479 DOI: 10.1016/j.cell.2015.06.015] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 03/27/2015] [Accepted: 06/01/2015] [Indexed: 10/31/2022]
Abstract
Repair of DNA double strand breaks by homologous recombination (HR) is initiated by Rad51 filament nucleation on single-stranded DNA (ssDNA), which catalyzes strand exchange with homologous duplex DNA. BRCA2 and the Rad51 paralogs are tumor suppressors and critical mediators of Rad51. To gain insight into Rad51 paralog function, we investigated a heterodimeric Rad51 paralog complex, RFS-1/RIP-1, and uncovered the molecular basis by which Rad51 paralogs promote HR. Unlike BRCA2, which nucleates RAD-51-ssDNA filaments, RFS-1/RIP-1 binds and remodels pre-synaptic filaments to a stabilized, "open," and flexible conformation, in which the ssDNA is more accessible to nuclease digestion and RAD-51 dissociation rate is reduced. Walker box mutations in RFS-1, which abolish filament remodeling, fail to stimulate RAD-51 strand exchange activity, demonstrating that remodeling is essential for RFS-1/RIP-1 function. We propose that Rad51 paralogs stimulate HR by remodeling the Rad51 filament, priming it for strand exchange with the template duplex.
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Affiliation(s)
- Martin R G Taylor
- DNA Damage Response Laboratory, Clare Hall Laboratory, The Francis Crick Institute, South Mimms EN6 3LD, UK
| | - Mário Špírek
- Department of Biology, Masaryk University, 62500 Brno, Czech Republic; International Clinical Research Center, St. Anne's University Hospital in Brno, 62500 Brno, Czech Republic
| | - Kathy R Chaurasiya
- Section of Virology, Single Molecule Imaging Group and MRC Clinical Sciences Centre, Department of Medicine, Imperial College London, London W12 0NN, UK
| | - Jordan D Ward
- DNA Damage Response Laboratory, Clare Hall Laboratory, The Francis Crick Institute, South Mimms EN6 3LD, UK; UCSF-Mission Bay, Genentech Hall S574, San Francisco, CA 94158, USA
| | - Raffaella Carzaniga
- Electron Microscopy Science Technology Platform, Lincoln's Inn Fields Laboratory, The Francis Crick Institute, London WC2A 3LY, UK
| | - Xiong Yu
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Lucy M Collinson
- Electron Microscopy Science Technology Platform, Lincoln's Inn Fields Laboratory, The Francis Crick Institute, London WC2A 3LY, UK
| | - David Rueda
- Section of Virology, Single Molecule Imaging Group and MRC Clinical Sciences Centre, Department of Medicine, Imperial College London, London W12 0NN, UK
| | - Lumir Krejci
- Department of Biology, Masaryk University, 62500 Brno, Czech Republic; International Clinical Research Center, St. Anne's University Hospital in Brno, 62500 Brno, Czech Republic; National Centre for Biomolecular Research, Masaryk University, 62500 Brno, Czech Republic.
| | - Simon J Boulton
- DNA Damage Response Laboratory, Clare Hall Laboratory, The Francis Crick Institute, South Mimms EN6 3LD, UK.
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63
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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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Okimoto S, Sun J, Fukuto A, Horikoshi Y, Matsuda S, Matsuda T, Ikura M, Ikura T, Machida S, Kurumizaka H, Miyamoto Y, Oka M, Yoneda Y, Kiuchi Y, Tashiro S. hCAS/CSE1L regulates RAD51 distribution and focus formation for homologous recombinational repair. Genes Cells 2015; 20:681-94. [PMID: 26123175 DOI: 10.1111/gtc.12262] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 05/14/2015] [Indexed: 01/05/2023]
Abstract
Homologous recombinational repair (HR) is one of the major repair systems for DNA double-strand breaks. RAD51 is a key molecule in HR, and the RAD51 concentration in the cell nucleus increases after DNA damage induction. However, the mechanism that regulates the intracellular distribution of RAD51 is still unclear. Here, we show that hCAS/CSE1L associates with RAD51 in human cells. We found that hCAS/CSE1L negatively regulates the nuclear protein level of RAD51 under normal conditions. hCAS/CSE1L is also required to repress the DNA damage-induced focus formation of RAD51. Moreover, we show that hCAS/CSE1L plays roles in the regulation of the HR activity and in chromosome stability. These findings suggest that hCAS/CSE1L is responsible for controlling the HR activity by directly interacting with RAD51.
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Affiliation(s)
- Satoshi Okimoto
- Department of Cellular Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, 734-8551, Japan.,Department of Ophthalmology and Visual Science, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, 734-8551, Japan
| | - Jiying Sun
- Department of Cellular Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, 734-8551, Japan
| | - Atsuhiko Fukuto
- Department of Cellular Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, 734-8551, Japan.,Department of Ophthalmology and Visual Science, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, 734-8551, Japan
| | - Yasunori Horikoshi
- Department of Cellular Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, 734-8551, Japan.,Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Hiroshima, 734-8551, Japan
| | - Shun Matsuda
- Research Center for Environmental Quality Management, Kyoto University, Otsu, Shiga, 520-0811, Japan
| | - Tomonari Matsuda
- Research Center for Environmental Quality Management, Kyoto University, Otsu, Shiga, 520-0811, Japan
| | - Masae Ikura
- Laboratory of Chromatin Regulatory Network, Department of Mutagenesis, Radiation Biology Center, Kyoto University, Yoshida Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Tsuyoshi Ikura
- Laboratory of Chromatin Regulatory Network, Department of Mutagenesis, Radiation Biology Center, Kyoto University, Yoshida Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Shinichi Machida
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan
| | - Hitoshi Kurumizaka
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan
| | - Yoichi Miyamoto
- National Institute of Biomedical Innovation, 7-6-8 Saito-Asagi, Ibaraki, Osaka, 567-0085, Japan
| | - Masahiro Oka
- National Institute of Biomedical Innovation, 7-6-8 Saito-Asagi, Ibaraki, Osaka, 567-0085, Japan
| | - Yoshihiro Yoneda
- National Institute of Biomedical Innovation, 7-6-8 Saito-Asagi, Ibaraki, Osaka, 567-0085, Japan
| | - Yoshiaki Kiuchi
- Department of Ophthalmology and Visual Science, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, 734-8551, Japan
| | - Satoshi Tashiro
- Department of Cellular Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, 734-8551, Japan.,Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Hiroshima, 734-8551, Japan
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65
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Abstract
The 2014 joint meeting of the International Society for Cellular Oncology (ISCO) and the European Workshop on Cytogenetics and Molecular Genetics of Solid Tumors (EWCMST), organized by Nick Gilbert, Juan Cigudosa and Bauke Ylstra, was held from 11 to 14 May in Malaga, Spain. Since the previous meeting in 2012, the ever increasing availability of new sequencing technologies has enabled the analysis of cancer genomes at an increasingly greater detail. In addition to structural changes in the genome (i.e., translocations, deletions, amplifications), frequent mutations in important regulatory genes have been found to occur, as also frequent alterations in a large number of epigenetic factors. The challenge now is to relate structural changes in cancer genomes to the underlying disease mechanisms and to reveal opportunities for the design of novel (targeted) therapies. During the meeting, various topics related to these challenges and opportunities were addressed, including those dealing with functional genomics, genome instability, biomarkers and diagnostics, cancer genetics and epigenomics. Special attention was paid to therapy-driven cancer evolution (keynote lecture) and relationships between DNA repair, cancer and ageing (Prof. Ploem lecture). Based on the information presented at the meeting, several aspects of the cancer genome and its functional implications are provided in this report.
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66
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Reuter M, Zelensky A, Smal I, Meijering E, van Cappellen WA, de Gruiter HM, van Belle GJ, van Royen ME, Houtsmuller AB, Essers J, Kanaar R, Wyman C. BRCA2 diffuses as oligomeric clusters with RAD51 and changes mobility after DNA damage in live cells. ACTA ACUST UNITED AC 2015; 207:599-613. [PMID: 25488918 PMCID: PMC4259808 DOI: 10.1083/jcb.201405014] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Nuclear BRCA2 is oligomeric and associated with RAD51, possibly sequestering it until it is delivered to DNA damage sites. Genome maintenance by homologous recombination depends on coordinating many proteins in time and space to assemble at DNA break sites. To understand this process, we followed the mobility of BRCA2, a critical recombination mediator, in live cells at the single-molecule level using both single-particle tracking and fluorescence correlation spectroscopy. BRCA2-GFP and -YFP were compared to distinguish diffusion from fluorophore behavior. Diffusive behavior of fluorescent RAD51 and RAD54 was determined for comparison. All fluorescent proteins were expressed from endogenous loci. We found that nuclear BRCA2 existed in oligomeric clusters, and exhibited heterogeneous mobility. DNA damage increased BRCA2 transient binding, presumably including binding to damaged sites. Despite its very different size, RAD51 displayed mobility similar to BRCA2, which indicates physical interaction between these proteins both before and after induction of DNA damage. We propose that BRCA2-mediated sequestration of nuclear RAD51 serves to prevent inappropriate DNA interactions and that all RAD51 is delivered to DNA damage sites in association with BRCA2.
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Affiliation(s)
- Marcel Reuter
- Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands
| | - Alex Zelensky
- Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands
| | - Ihor Smal
- Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands
| | - Erik Meijering
- Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands
| | - Wiggert A van Cappellen
- Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands
| | - H Martijn de Gruiter
- Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands
| | - Gijsbert J van Belle
- Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands
| | - Martin E van Royen
- Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands
| | - Adriaan B Houtsmuller
- Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands
| | - Jeroen Essers
- Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands
| | - Roland Kanaar
- Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands
| | - Claire Wyman
- Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands Department of Genetics, Cancer Genomics Centre Netherlands, Department of Medical Informatics, Department of Radiology, Erasmus Optical Imaging Centre, Department of Pathology, Department of Vascular Surgery, and Department of Radiation Oncology, Erasmus University Medical Centre, 3000 CA Rotterdam, Netherlands
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67
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Coppa A, Buffone A, Capalbo C, Nicolussi A, D'Inzeo S, Belardinilli F, Colicchia V, Petroni M, Granato T, Midulla C, Zani M, Ferraro S, Screpanti I, Gulino A, Giannini G. Novel and recurrent BRCA2 mutations in Italian breast/ovarian cancer families widen the ovarian cancer cluster region boundaries to exons 13 and 14. Breast Cancer Res Treat 2014; 148:629-35. [PMID: 25395318 DOI: 10.1007/s10549-014-3196-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 11/03/2014] [Indexed: 12/20/2022]
Abstract
Hereditary breast and ovarian cancer are mainly linked to mutations in BRCA1 and BRCA2 genes which confer a similar cumulative risk of developing breast cancer. Importantly, while BRCA2 mutation carriers generally have a lower cumulative risk for ovarian cancer, mutations clustered in the central portion of BRCA2 are associated with a higher proportion of ovarian compared with breast cancer cases. The boundaries of this ovarian cancer cluster region (OCCR) have been tentatively defined within a 3.3 kb region of BRCA2 exon 11, and herein, we reassessed these boundaries using our series of Italian breast/ovarian cancer families. We used direct sequencing to investigate BRCA mutations in 367 breast/ovarian cancer families. We also studied the association between the location of the mutations and the ovarian cancer phenotype in our cohort of BRCA2-mutated families. We observed the novel c.7309_7309delA frameshift mutation and the c.7007G>A deleterious mutation in BRCA2 exons 14 and 13, respectively, in five independent Italian families characterized by a high proportion of ovarian cancer cases. Of note, a significantly higher proportion of ovarian versus breast cancer cases was associated not only with mutations in the previously defined OCCR (OR = 5.91; p = 0.004), but also with the exon 13-14 region (OR = 7.37; p = 0.001) in our BRCA2-mutated families. Our data provide initial evidence for a novel putative OCCR in BRCA2 exons 13-14.
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Affiliation(s)
- Anna Coppa
- Department of Experimental Medicine, University La Sapienza, v. le R. Elena 324, 00161, Rome, Italy
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68
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Qin Q, Xie H, Wise SS, Browning CL, Thompson KN, Holmes AL, Wise JP. Homologous recombination repair signaling in chemical carcinogenesis: prolonged particulate hexavalent chromium exposure suppresses the Rad51 response in human lung cells. Toxicol Sci 2014; 142:117-25. [PMID: 25173789 DOI: 10.1093/toxsci/kfu175] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The aim of this study was to focus on hexavalent chromium, [Cr(VI)], a chemical carcinogen and major public health concern, and consider its ability to impact DNA double strand break repair. We further focused on particulate Cr(VI), because it is the more potent carcinogenic form of Cr(VI). DNA double strand break repair serves to protect cells against the detrimental effects of DNA double strand breaks. For particulate Cr(VI), data show DNA double strand break repair must be overcome for neoplastic transformation to occur. Acute Cr(VI) exposures reveal a robust DNA double strand break repair response, however, longer exposures have not been considered. Using the comet assay, we found longer exposures to particulate zinc chromate induced concentration-dependent increases in DNA double strand breaks indicating breaks were occurring throughout the exposure time. Acute (24 h) exposure induced DNA double strand break repair signaling by inducing Mre11 foci formation, ATM phosphorylation and phosphorylated ATM foci formation, Rad51 protein levels and Rad51 foci formation. However, longer exposures reduced the Rad51 response. These data indicate a major chemical carcinogen can simultaneously induce DNA double strand breaks and alter their repair and describe a new and important aspect of the carcinogenic mechanism for Cr(VI).
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Affiliation(s)
- Qin Qin
- The Wise Laboratory of Environmental and Genetic Toxicology, Maine Center for Toxicology and Environmental Health, Department of Applied Medical Sciences, University of Southern Maine, 96 Falmouth Street, Portland, Maine 04104-9300
| | - Hong Xie
- The Wise Laboratory of Environmental and Genetic Toxicology, Maine Center for Toxicology and Environmental Health, Department of Applied Medical Sciences, University of Southern Maine, 96 Falmouth Street, Portland, Maine 04104-9300
| | - Sandra S Wise
- The Wise Laboratory of Environmental and Genetic Toxicology, Maine Center for Toxicology and Environmental Health, Department of Applied Medical Sciences, University of Southern Maine, 96 Falmouth Street, Portland, Maine 04104-9300
| | - Cynthia L Browning
- The Wise Laboratory of Environmental and Genetic Toxicology, Maine Center for Toxicology and Environmental Health, Department of Applied Medical Sciences, University of Southern Maine, 96 Falmouth Street, Portland, Maine 04104-9300
| | - Kelsey N Thompson
- The Wise Laboratory of Environmental and Genetic Toxicology, Maine Center for Toxicology and Environmental Health, Department of Applied Medical Sciences, University of Southern Maine, 96 Falmouth Street, Portland, Maine 04104-9300
| | - Amie L Holmes
- The Wise Laboratory of Environmental and Genetic Toxicology, Maine Center for Toxicology and Environmental Health, Department of Applied Medical Sciences, University of Southern Maine, 96 Falmouth Street, Portland, Maine 04104-9300
| | - John Pierce Wise
- The Wise Laboratory of Environmental and Genetic Toxicology, Maine Center for Toxicology and Environmental Health, Department of Applied Medical Sciences, University of Southern Maine, 96 Falmouth Street, Portland, Maine 04104-9300
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69
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Upadhyay RK. Drug delivery systems, CNS protection, and the blood brain barrier. BIOMED RESEARCH INTERNATIONAL 2014; 2014:869269. [PMID: 25136634 PMCID: PMC4127280 DOI: 10.1155/2014/869269] [Citation(s) in RCA: 211] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 05/31/2014] [Accepted: 06/05/2014] [Indexed: 12/12/2022]
Abstract
Present review highlights various drug delivery systems used for delivery of pharmaceutical agents mainly antibiotics, antineoplastic agents, neuropeptides, and other therapeutic substances through the endothelial capillaries (BBB) for CNS therapeutics. In addition, the use of ultrasound in delivery of therapeutic agents/biomolecules such as proline rich peptides, prodrugs, radiopharmaceuticals, proteins, immunoglobulins, and chimeric peptides to the target sites in deep tissue locations inside tumor sites of brain has been explained. In addition, therapeutic applications of various types of nanoparticles such as chitosan based nanomers, dendrimers, carbon nanotubes, niosomes, beta cyclodextrin carriers, cholesterol mediated cationic solid lipid nanoparticles, colloidal drug carriers, liposomes, and micelles have been discussed with their recent advancements. Emphasis has been given on the need of physiological and therapeutic optimization of existing drug delivery methods and their carriers to deliver therapeutic amount of drug into the brain for treatment of various neurological diseases and disorders. Further, strong recommendations are being made to develop nanosized drug carriers/vehicles and noninvasive therapeutic alternatives of conventional methods for better therapeutics of CNS related diseases. Hence, there is an urgent need to design nontoxic biocompatible drugs and develop noninvasive delivery methods to check posttreatment clinical fatalities in neuropatients which occur due to existing highly toxic invasive drugs and treatment methods.
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Affiliation(s)
- Ravi Kant Upadhyay
- Department of Zoology, DDU Gorakhpur University, Gorakhpur 273009, India
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70
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Abstract
Germline mutations in BRCA1 and BRCA2 predispose to common human malignancies, most notably tumors of the breast and ovaries. The proteins encoded by these genes have been implicated in a plethora of biochemical interactions and biological functions, confounding attempts to coherently explain how their inactivation promotes carcinogenesis. Here, I argue that tumor suppression by BRCA1 and BRCA2 originates from their fundamental role in controlling the assembly and activity of macromolecular complexes that monitor chromosome duplication, maintenance, and segregation across the cell cycle. A tumor-suppressive role for the BRCA proteins as "chromosome custodians" helps to explain the clinical features of cancer susceptibility after their inactivation, provides foundations for the rational therapy of BRCA-deficient cancers, and offers general insights into the mechanisms opposing early steps in human carcinogenesis.
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Affiliation(s)
- Ashok R Venkitaraman
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
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71
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Nuclear trafficking in health and disease. Curr Opin Cell Biol 2014; 28:28-35. [PMID: 24530809 DOI: 10.1016/j.ceb.2014.01.007] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 01/12/2014] [Accepted: 01/19/2014] [Indexed: 01/07/2023]
Abstract
In eukaryotic cells, the cytoplasm and the nucleus are separated by a double-membraned nuclear envelope (NE). Thus, transport of molecules between the nucleus and the cytoplasm occurs via gateways termed the nuclear pore complexes (NPCs), which are the largest intracellular channels in nature. While small molecules can passively translocate through the NPC, large molecules are actively imported into the nucleus by interacting with receptors that bind nuclear pore complex proteins (Nups). Regulatory factors then function in assembly and disassembly of transport complexes. Signaling pathways, cell cycle, pathogens, and other physiopathological conditions regulate various constituents of the nuclear transport machinery. Here, we will discuss several findings related to modulation of nuclear transport during physiological and pathological conditions, including tumorigenesis, viral infection, and congenital syndrome. We will also explore chemical biological approaches that are being used as probes to reveal new mechanisms that regulate nucleocytoplasmic trafficking and that are serving as starting points for drug development.
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72
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Venkitaraman AR. Tumour suppressor mechanisms in the control of chromosome stability: insights from BRCA2. Mol Cells 2014; 37:95-9. [PMID: 24598993 PMCID: PMC3935635 DOI: 10.14348/molcells.2014.2346] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 11/23/2013] [Indexed: 12/13/2022] Open
Abstract
Cancer is unique amongst human diseases in that its cellular manifestations arise and evolve through the acquisition of somatic alterations in the genome. In particular, instability in the number and structure of chromosomes is a near-universal feature of the genomic alterations associated with epithelial cancers, and is triggered by the inactivation of tumour suppressor mechanisms that preserve chromosome integrity in normal cells. The nature of these mechanisms, and how their inactivation promotes carcinogenesis, remains enigmatic. I will review recent work from our laboratory on the tumour suppressor BRCA2 that addresses these issues, focusing on new insights into cancer pathogenesis and therapy that are emerging from improved understanding of the molecular basis of chromosomal instability in BRCA2-deficient cancer cells.
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Affiliation(s)
- Ashok R. Venkitaraman
- University of Cambridge, Medical Research Council Cancer Unit, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 0XZ,
United Kingdom
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73
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Guidugli L, Carreira A, Caputo SM, Ehlen A, Galli A, Monteiro ANA, Neuhausen SL, Hansen TVO, Couch FJ, Vreeswijk MPG. Functional assays for analysis of variants of uncertain significance in BRCA2. Hum Mutat 2013; 35:151-64. [PMID: 24323938 DOI: 10.1002/humu.22478] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 10/28/2013] [Indexed: 01/11/2023]
Abstract
Missense variants in the BRCA2 gene are routinely detected during clinical screening for pathogenic mutations in patients with a family history of breast and ovarian cancer. These subtle changes frequently remain of unknown clinical significance because of the lack of genetic information that may help establish a direct correlation with cancer predisposition. Therefore, alternative ways of predicting the pathogenicity of these variants are urgently needed. Since BRCA2 is a protein involved in important cellular mechanisms such as DNA repair, replication, and cell cycle control, functional assays have been developed that exploit these cellular activities to explore the impact of the variants on protein function. In this review, we summarize assays developed and currently utilized for studying missense variants in BRCA2. We specifically depict details of each assay, including variants of uncertain significance analyzed, and describe a validation set of (genetically) proven pathogenic and neutral missense variants to serve as a golden standard for the validation of each assay. Guidelines are proposed to enable implementation of laboratory-based methods to assess the impact of the variant on cancer risk.
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Affiliation(s)
- Lucia Guidugli
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
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74
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Compensatory Functions and Interdependency of the DNA-Binding Domain of BRCA2 with the BRCA1–PALB2–BRCA2 Complex. Cancer Res 2013; 74:797-807. [DOI: 10.1158/0008-5472.can-13-1443] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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