1
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Miron S, Legrand P, Dupaigne P, van Rossum-Fikkert SE, Ristic D, Majeed A, Kanaar R, Zinn-Justin S, Zelensky A. DMC1 and RAD51 bind FxxA and FxPP motifs of BRCA2 via two separate interfaces. Nucleic Acids Res 2024; 52:7337-7353. [PMID: 38828772 PMCID: PMC11229353 DOI: 10.1093/nar/gkae452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 04/29/2024] [Accepted: 05/29/2024] [Indexed: 06/05/2024] Open
Abstract
In vertebrates, the BRCA2 protein is essential for meiotic and somatic homologous recombination due to its interaction with the RAD51 and DMC1 recombinases through FxxA and FxPP motifs (here named A- and P-motifs, respectively). The A-motifs present in the eight BRC repeats of BRCA2 compete with the A-motif of RAD51, which is responsible for its self-oligomerization. BRCs thus disrupt RAD51 nucleoprotein filaments in vitro. The role of the P-motifs is less studied. We recently found that deletion of Brca2 exons 12-14 encoding one of them (the prototypical 'PhePP' motif), disrupts DMC1 but not RAD51 function in mouse meiosis. Here we provide a mechanistic explanation for this phenotype by solving the crystal structure of the complex between a BRCA2 fragment containing the PhePP motif and DMC1. Our structure reveals that, despite sharing a conserved phenylalanine, the A- and P-motifs bind to distinct sites on the ATPase domain of the recombinases. The P-motif interacts with a site that is accessible in DMC1 octamers and nucleoprotein filaments. Moreover, we show that this interaction also involves the adjacent protomer and thus increases the stability of the DMC1 nucleoprotein filaments. We extend our analysis to other P-motifs from RAD51AP1 and FIGNL1.
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Affiliation(s)
- Simona Miron
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | - Pierre Legrand
- Synchrotron SOLEIL, HelioBio group, L’Orme des Merisiers, Gif sur-Yvette, France
| | - Pauline Dupaigne
- Genome Maintenance and Molecular Microscopy UMR 9019 CNRS, Université Paris-Saclay, Gustave Roussy, Villejuif, France
| | - Sari E van Rossum-Fikkert
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3000CA, Rotterdam, The Netherlands
| | - Dejan Ristic
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3000CA, Rotterdam, The Netherlands
| | - Atifa Majeed
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | - Roland Kanaar
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3000CA, Rotterdam, The Netherlands
- Oncode Institute, Erasmus University Medical Center, 3000CA, Rotterdam, The Netherlands
| | - Sophie Zinn-Justin
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | - Alex N Zelensky
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3000CA, Rotterdam, The Netherlands
- Oncode Institute, Erasmus University Medical Center, 3000CA, Rotterdam, The Netherlands
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2
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Palihati M, Iwasaki H, Tsubouchi H. Analysis of the indispensable RAD51 cofactor BRCA2 in Naganishia liquefaciens, a Basidiomycota yeast. Life Sci Alliance 2024; 7:e202302342. [PMID: 38016757 PMCID: PMC10684384 DOI: 10.26508/lsa.202302342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 11/16/2023] [Accepted: 11/20/2023] [Indexed: 11/30/2023] Open
Abstract
The BRCA2 tumor suppressor plays a critical role in homologous recombination by regulating RAD51, the eukaryotic homologous recombinase. We identified the BRCA2 homolog in a Basidiomycota yeast, Naganishia liquefaciens BRCA2 homologs are found in many Basidiomycota species but not in Ascomycota species. Naganishia BRCA2 (Brh2, for BRCA2 homolog) is about one-third the size of human BRCA2. Brh2 carries three potential BRC repeats with two oligonucleotide/oligosaccharide-binding domains. The homolog of DSS1, a small acidic protein serving as an essential partner of BRCA2 was also identified. The yeast two-hybrid assay shows the interaction of Brh2 with both Rad51 and Dss1. Unlike human BRCA2, Brh2 is not required for normal cell growth, whereas loss of Dss1 results in slow growth. The loss of Brh2 caused pronounced sensitivity to UV and ionizing radiation, and their HR ability, as assayed by gene-targeting efficiency, is compromised. These phenotypes are indistinguishable from those of the rad51 mutant, and the rad51 brh2 double mutant. Naganishia Brh2 is likely the BRCA2 ortholog that functions as an indispensable auxiliary factor for Rad51.
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Affiliation(s)
- Maierdan Palihati
- https://ror.org/0112mx960 Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Hiroshi Iwasaki
- https://ror.org/0112mx960 Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Hideo Tsubouchi
- https://ror.org/0112mx960 Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
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3
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Appleby R, Joudeh L, Cobbett K, Pellegrini L. Structural basis for stabilisation of the RAD51 nucleoprotein filament by BRCA2. Nat Commun 2023; 14:7003. [PMID: 37919288 PMCID: PMC10622577 DOI: 10.1038/s41467-023-42830-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 10/23/2023] [Indexed: 11/04/2023] Open
Abstract
The BRCA2 tumour suppressor protein preserves genomic integrity via interactions with the DNA-strand exchange RAD51 protein in homology-directed repair. The RAD51-binding TR2 motif at the BRCA2 C-terminus is essential for protection and restart of stalled replication forks. Biochemical evidence shows that TR2 recognises filamentous RAD51, but existing models of TR2 binding to RAD51 lack a structural basis. Here we used cryo-electron microscopy and structure-guided mutagenesis to elucidate the mechanism of TR2 binding to nucleoprotein filaments of human RAD51. We find that TR2 binds across the protomer interface in the filament, acting as a brace for adjacent RAD51 molecules. TR2 targets an acidic-patch motif on human RAD51 that serves as a recruitment hub in fission yeast Rad51 for recombination mediators Rad52 and Rad55-Rad57. Our findings provide a structural rationale for RAD51 filament stabilisation by BRCA2 and reveal a common recruitment mechanism of recombination mediators to the RAD51 filament.
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Affiliation(s)
- Robert Appleby
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
| | - Luay Joudeh
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
| | - Katie Cobbett
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
| | - Luca Pellegrini
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK.
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4
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Sutherland JH, Holloman WK. Determinants governing BRC function evaluated by mutational analysis of Brh2 in Ustilago maydis. DNA Repair (Amst) 2023; 127:103511. [PMID: 37141696 DOI: 10.1016/j.dnarep.2023.103511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 03/31/2023] [Accepted: 04/24/2023] [Indexed: 05/06/2023]
Abstract
BRC is a short evolutionarily conserved sequence motif generally arranged in multiple tandem repeats that is present as a defining feature in members of the BRCA2 tumor suppressor protein family. From crystallographic studies of a co-complex, the human BRC4 was found to form a structural element that interacts with RAD51, a key component in the DNA repair machinery directed by homologous recombination. The BRC is distinguished by two tetrameric sequence modules with characteristic hydrophobic residues separated by an intervening spacer region marked by certain highly conserved residues forming a hydrophobic surface for interaction with RAD51. It is present as a single copy in Brh2 of Ustilago maydis, the only reported example of a fungal BRCA2 ortholog. By comparative sequence analysis, examples of BRCA2 orthologs were identified in other fungal phyla, some of which featured multiple tandem repeats like those found in mammals. An expeditious biological assay system was developed for evaluating the two-tetramer module model and assessing the importance of particular conserved amino acid residues of BRC contributing to Brh2 functionality in DNA repair. This work was aided by the finding that the human BRC4 repeat could substitute completely for the endogenous BRC element in Brh2, while the human BRC5 repeat could not. In a survey of point mutations of certain residues, certain BRC mutant variants termed antimorphs were identified that caused a DNA repair phenotype more severe than the null.
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Affiliation(s)
- Jeanette H Sutherland
- Department of Microbiology and Immunology, Cornell University Weill Medical College, New York, NY 10065, USA; Department of Biology, Farmingdale State College, Farmingdale, NY 11735, USA.
| | - William K Holloman
- Department of Microbiology and Immunology, Cornell University Weill Medical College, New York, NY 10065, USA
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5
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Bell JC, Dombrowski CC, Plank JL, Jensen RB, Kowalczykowski SC. BRCA2 chaperones RAD51 to single molecules of RPA-coated ssDNA. Proc Natl Acad Sci U S A 2023; 120:e2221971120. [PMID: 36976771 PMCID: PMC10083600 DOI: 10.1073/pnas.2221971120] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 02/24/2023] [Indexed: 03/29/2023] Open
Abstract
Mutations in the breast cancer susceptibility gene, BRCA2, greatly increase an individual's lifetime risk of developing breast and ovarian cancers. BRCA2 suppresses tumor formation by potentiating DNA repair via homologous recombination. Central to recombination is the assembly of a RAD51 nucleoprotein filament, which forms on single-stranded DNA (ssDNA) generated at or near the site of chromosomal damage. However, replication protein-A (RPA) rapidly binds to and continuously sequesters this ssDNA, imposing a kinetic barrier to RAD51 filament assembly that suppresses unregulated recombination. Recombination mediator proteins-of which BRCA2 is the defining member in humans-alleviate this kinetic barrier to catalyze RAD51 filament formation. We combined microfluidics, microscopy, and micromanipulation to directly measure both the binding of full-length BRCA2 to-and the assembly of RAD51 filaments on-a region of RPA-coated ssDNA within individual DNA molecules designed to mimic a resected DNA lesion common in replication-coupled recombinational repair. We demonstrate that a dimer of RAD51 is minimally required for spontaneous nucleation; however, growth self-terminates below the diffraction limit. BRCA2 accelerates nucleation of RAD51 to a rate that approaches the rapid association of RAD51 to naked ssDNA, thereby overcoming the kinetic block imposed by RPA. Furthermore, BRCA2 eliminates the need for the rate-limiting nucleation of RAD51 by chaperoning a short preassembled RAD51 filament onto the ssDNA complexed with RPA. Therefore, BRCA2 regulates recombination by initiating RAD51 filament formation.
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Affiliation(s)
- Jason C. Bell
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA95616
- Department of Molecular and Cellular Biology, University of California, Davis, CA95616
| | - Christopher C. Dombrowski
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA95616
- Department of Molecular and Cellular Biology, University of California, Davis, CA95616
| | - Jody L. Plank
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA95616
- Department of Molecular and Cellular Biology, University of California, Davis, CA95616
| | - Ryan B. Jensen
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA95616
- Department of Molecular and Cellular Biology, University of California, Davis, CA95616
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT06520
| | - Stephen C. Kowalczykowski
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA95616
- Department of Molecular and Cellular Biology, University of California, Davis, CA95616
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6
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Zhang X, Ma D, Xuan B, Shi D, He J, Yu M, Xiong H, Ma Y, Shen C, Guo F, Cao Y, Yan Y, Gao Z, Tong T, Zhu X, Fang JY, Chen H, Hong J. LncRNA CACClnc promotes chemoresistance of colorectal cancer by modulating alternative splicing of RAD51. Oncogene 2023; 42:1374-1391. [PMID: 36906654 DOI: 10.1038/s41388-023-02657-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 02/24/2023] [Accepted: 02/27/2023] [Indexed: 03/13/2023]
Abstract
Long non-coding RNAs (lncRNAs) play important roles in carcinogenesis. However, the effect of lncRNA on chemoresistance and RNA alternative splicing remains largely unknown. In this study, we identified a novel lncRNA, CACClnc, which was upregulated and associated with chemoresistance and poor prognosis in colorectal cancer (CRC). CACClnc promoted CRC resistance to chemotherapy via promoting DNA repair and enhancing homologous recombination in vitro and in vivo. Mechanistically, CACClnc specifically bound to Y-box binding protein 1 (YB1, a splicing factor) and U2AF65 (a subunit of U2AF splicing factor), promoting the interaction between YB1 and U2AF65, and then modulated alternative splicing (AS) of RAD51 mRNA, and consequently altered CRC cell biology. In addition, expression of exosomal CACClnc in peripheral plasma of CRC patients can effectively predict the chemotherapy effect of patients before treatment. Thus, measuring and targeting CACClnc and its associated pathway could yield valuable insight into clinical management and might ameliorate CRC patients' outcomes.
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Affiliation(s)
- Xinyu Zhang
- State Key Laboratory for Oncogenes and Related Genes, NHC Key Laboratory of Digestive Diseases, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Dan Ma
- State Key Laboratory for Oncogenes and Related Genes, NHC Key Laboratory of Digestive Diseases, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.,Department of Gastroenterology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Baoqin Xuan
- State Key Laboratory for Oncogenes and Related Genes, NHC Key Laboratory of Digestive Diseases, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Debing Shi
- Department of Colorectal Surgery, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jie He
- Guangzhou Key Laboratory of Digestive Disease, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital and The Second Affiliated Hospital, South China University of Technology School of Medicine, Guangzhou, China
| | - Minhao Yu
- Department of Gastrointestinal Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Hua Xiong
- State Key Laboratory for Oncogenes and Related Genes, NHC Key Laboratory of Digestive Diseases, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yanru Ma
- State Key Laboratory for Oncogenes and Related Genes, NHC Key Laboratory of Digestive Diseases, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Chaoqin Shen
- State Key Laboratory for Oncogenes and Related Genes, NHC Key Laboratory of Digestive Diseases, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Fangfang Guo
- State Key Laboratory for Oncogenes and Related Genes, NHC Key Laboratory of Digestive Diseases, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yingying Cao
- State Key Laboratory for Oncogenes and Related Genes, NHC Key Laboratory of Digestive Diseases, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yuqing Yan
- State Key Laboratory for Oncogenes and Related Genes, NHC Key Laboratory of Digestive Diseases, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Ziyun Gao
- State Key Laboratory for Oncogenes and Related Genes, NHC Key Laboratory of Digestive Diseases, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Tianying Tong
- State Key Laboratory for Oncogenes and Related Genes, NHC Key Laboratory of Digestive Diseases, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xiaoqiang Zhu
- State Key Laboratory for Oncogenes and Related Genes, NHC Key Laboratory of Digestive Diseases, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jing-Yuan Fang
- State Key Laboratory for Oncogenes and Related Genes, NHC Key Laboratory of Digestive Diseases, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Haoyan Chen
- State Key Laboratory for Oncogenes and Related Genes, NHC Key Laboratory of Digestive Diseases, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
| | - Jie Hong
- State Key Laboratory for Oncogenes and Related Genes, NHC Key Laboratory of Digestive Diseases, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
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7
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Zhu Z, Kitano T, Morimatsu M, Ochiai K, Ishiguro-Oonuma T, Oosumi K, Lin X, Orino K, Yoshikawa Y. A Highly Conserved Region in BRCA2 Suppresses the RAD51-Interaction Activity of BRC Repeats. Vet Sci 2023; 10:vetsci10020145. [PMID: 36851449 PMCID: PMC9959916 DOI: 10.3390/vetsci10020145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 01/30/2023] [Accepted: 02/07/2023] [Indexed: 02/15/2023] Open
Abstract
Mammary tumors are the most prevalent type of tumors in female dogs. Breast cancer 2, early onset (BRCA2) malignant mutations are associated with tumorigenesis in humans and dogs. BRCA2 plays a pivotal role in homologous recombination repair by recruiting RAD51 recombinase to DNA damage sites to maintain genome stability. To recruit RAD51, BRCA2 must interact with RAD51 via BRC repeats, but the regulation of this interaction has been unclear. In this study, we focused on a highly conserved region (HCR) near BRC repeats. Using co-immunoprecipitation and mammalian two-hybrid assay, we found that HCR suppressed the RAD51-interaction activity of BRC repeats and that substitutions of HCR phosphorylation sites affected it. In canine tumor samples, we found ten mutations, including a novel HCR mutation (I1110M) from canine tumor samples. The effect of four HCR mutations, including I1110M, on the RAD51-interaction activity of BRC repeats was tested. One of the HCR mutations found in canine mammary tumors increased the interaction, but the two mutations found in human breast cancers decreased it. This study suggested that the HCR regulated the RAD51-interacting activity of BRC repeats through HCR phosphorylation and that mutations in HCR may be related to tumorigenesis in both dogs and humans.
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Affiliation(s)
- Zida Zhu
- Laboratory of Veterinary Biochemistry, School of Veterinary Medicine, Kitasato University, Towada 034-8628, Japan
| | - Taisuke Kitano
- Laboratory of Veterinary Biochemistry, School of Veterinary Medicine, Kitasato University, Towada 034-8628, Japan
| | - Masami Morimatsu
- Laboratory of Laboratory Animal Science and Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan
| | - Kazuhiko Ochiai
- Laboratory of Veterinary Hygiene, School of Veterinary Medicine, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
| | - Toshina Ishiguro-Oonuma
- Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka 020-8550, Japan
| | - Kosuke Oosumi
- Laboratory of Veterinary Biochemistry, School of Veterinary Medicine, Kitasato University, Towada 034-8628, Japan
| | - Xianghui Lin
- Laboratory of Veterinary Biochemistry, School of Veterinary Medicine, Kitasato University, Towada 034-8628, Japan
| | - Koichi Orino
- Laboratory of Veterinary Biochemistry, School of Veterinary Medicine, Kitasato University, Towada 034-8628, Japan
| | - Yasunaga Yoshikawa
- Laboratory of Veterinary Biochemistry, School of Veterinary Medicine, Kitasato University, Towada 034-8628, Japan
- Correspondence:
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8
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Jimenez-Sainz J, Mathew J, Moore G, Lahiri S, Garbarino J, Eder JP, Rothenberg E, Jensen RB. BRCA2 BRC missense variants disrupt RAD51-dependent DNA repair. eLife 2022; 11:e79183. [PMID: 36098506 PMCID: PMC9545528 DOI: 10.7554/elife.79183] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 09/12/2022] [Indexed: 11/24/2022] Open
Abstract
Pathogenic mutations in the BRCA2 tumor suppressor gene predispose to breast, ovarian, pancreatic, prostate, and other cancers. BRCA2 maintains genome stability through homology-directed repair (HDR) of DNA double-strand breaks (DSBs) and replication fork protection. Nonsense or frameshift mutations leading to truncation of the BRCA2 protein are typically considered pathogenic; however, missense mutations resulting in single amino acid substitutions can be challenging to functionally interpret. The majority of missense mutations in BRCA2 have been classified as Variants of Uncertain Significance (VUS) with unknown functional consequences. In this study, we identified three BRCA2 VUS located within the BRC repeat region to determine their impact on canonical HDR and fork protection functions. We provide evidence that S1221P and T1980I, which map to conserved residues in the BRC2 and BRC7 repeats, compromise the cellular response to chemotherapeutics and ionizing radiation, and display deficits in fork protection. We further demonstrate biochemically that S1221P and T1980I disrupt RAD51 binding and diminish the ability of BRCA2 to stabilize RAD51-ssDNA complexes. The third variant, T1346I, located within the spacer region between BRC2 and BRC3 repeats, is fully functional. We conclude that T1346I is a benign allele, whereas S1221P and T1980I are hypomorphic disrupting the ability of BRCA2 to fully engage and stabilize RAD51 nucleoprotein filaments. Our results underscore the importance of correctly classifying BRCA2 VUS as pathogenic variants can impact both future cancer risk and guide therapy selection during cancer treatment.
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Affiliation(s)
| | - Joshua Mathew
- Department of Therapeutic Radiology, Yale UniversityNew HavenUnited States
| | - Gemma Moore
- Department of Therapeutic Radiology, Yale UniversityNew HavenUnited States
| | - Sudipta Lahiri
- Department of Therapeutic Radiology, Yale UniversityNew HavenUnited States
| | - Jennifer Garbarino
- Department of Therapeutic Radiology, Yale UniversityNew HavenUnited States
| | - Joseph P Eder
- Department of Medical Oncology, Yale University School of Medicine, Yale Cancer CenterNew HavenUnited States
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, New York UniversityNew YorkUnited States
| | - Ryan B Jensen
- Department of Therapeutic Radiology, Yale UniversityNew HavenUnited States
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9
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Di Giacomo D, Di Domenico M, Defourny SVP, Malatesta D, Di Teodoro G, Martino M, Viola A, D’Alterio N, Cammà C, Modesto P, Petrini A. Validation of AmpliSeq NGS Panel for BRCA1 and BRCA2 Variant Detection in Canine Formalin-Fixed Paraffin-Embedded Mammary Tumors. Life (Basel) 2022; 12:life12060851. [PMID: 35743882 PMCID: PMC9225004 DOI: 10.3390/life12060851] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 05/25/2022] [Accepted: 05/30/2022] [Indexed: 12/01/2022] Open
Abstract
Mammary carcinomas are the most common neoplasms observed in women and in female dogs. Canine mammary tumors show epidemiological, clinical, genetic, and prognostic characteristics comparable to human breast cancers. The recent introduction of next generation sequencing (NGS) technologies has greatly improved research and diagnostics for humans, while these new tools still need to be implemented in animal models. In this study we developed and validated an AmpliSeq Panel assay for the identification of BRCA variants in twenty-two different dogs. The amplicon mean coverage was 5499× and uniformity was higher than 98% in all samples. The results of germline single nucleotide variants (SNVs) and insertions/deletions (INDELs) were fully concordant regardless of the types of samples considered (blood, fresh and FFPE tissues). Moreover, despite the high DNA degradation observed in older FFPE blocks (>5 years), the assay allowed full coverage of all amplicons for downstream analyses. We consider the NGS panel developed in this study as a useful tool for expanding information on BRCA genes in the veterinary field and for human health from a comparative oncology perspective.
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Affiliation(s)
- Daniela Di Giacomo
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Campo Boario, 64100 Teramo, Italy; (M.D.D.); (S.V.P.D.); (D.M.); (G.D.T.); (M.M.); (N.D.); (C.C.); (A.P.)
- National Reference Center for Whole Genome Sequencing of Microbial Pathogens: Database and Bioinformatic Analysis, Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, Campo Boario, 64100 Teramo, Italy
- Correspondence:
| | - Marco Di Domenico
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Campo Boario, 64100 Teramo, Italy; (M.D.D.); (S.V.P.D.); (D.M.); (G.D.T.); (M.M.); (N.D.); (C.C.); (A.P.)
- National Reference Center for Whole Genome Sequencing of Microbial Pathogens: Database and Bioinformatic Analysis, Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, Campo Boario, 64100 Teramo, Italy
| | - Sabrina Vanessa Patrizia Defourny
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Campo Boario, 64100 Teramo, Italy; (M.D.D.); (S.V.P.D.); (D.M.); (G.D.T.); (M.M.); (N.D.); (C.C.); (A.P.)
| | - Daniela Malatesta
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Campo Boario, 64100 Teramo, Italy; (M.D.D.); (S.V.P.D.); (D.M.); (G.D.T.); (M.M.); (N.D.); (C.C.); (A.P.)
| | - Giovanni Di Teodoro
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Campo Boario, 64100 Teramo, Italy; (M.D.D.); (S.V.P.D.); (D.M.); (G.D.T.); (M.M.); (N.D.); (C.C.); (A.P.)
| | - Michele Martino
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Campo Boario, 64100 Teramo, Italy; (M.D.D.); (S.V.P.D.); (D.M.); (G.D.T.); (M.M.); (N.D.); (C.C.); (A.P.)
| | - Antonello Viola
- Veterinary Practitioner, Centro Veterinario Nova Julia, Via Galileo Galilei 177, 64021 Giulianova, Italy;
| | - Nicola D’Alterio
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Campo Boario, 64100 Teramo, Italy; (M.D.D.); (S.V.P.D.); (D.M.); (G.D.T.); (M.M.); (N.D.); (C.C.); (A.P.)
| | - Cesare Cammà
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Campo Boario, 64100 Teramo, Italy; (M.D.D.); (S.V.P.D.); (D.M.); (G.D.T.); (M.M.); (N.D.); (C.C.); (A.P.)
- National Reference Center for Whole Genome Sequencing of Microbial Pathogens: Database and Bioinformatic Analysis, Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, Campo Boario, 64100 Teramo, Italy
| | - Paola Modesto
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d’Aosta, Via Bologna 148, 10154 Torino, Italy;
| | - Antonio Petrini
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Campo Boario, 64100 Teramo, Italy; (M.D.D.); (S.V.P.D.); (D.M.); (G.D.T.); (M.M.); (N.D.); (C.C.); (A.P.)
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10
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Milsted C, Dai B, Garcia N, Yin L, He Y, Kianian S, Pawlowski W, Chen C. Genome-wide investigation of maize RAD51 binding affinity through phage display. BMC Genomics 2022; 23:199. [PMID: 35279087 PMCID: PMC8917730 DOI: 10.1186/s12864-022-08419-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Accepted: 02/18/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
RAD51 proteins, which are conserved in all eukaryotes, repair DNA double-strand breaks. This is critical to homologous chromosome pairing and recombination enabling successful reproduction. Work in Arabidopsis suggests that RAD51 also plays a role in plant defense; the Arabidopsis rad51 mutant is more susceptible to Pseudomonas syringae. However, the defense functions of RAD51 and the proteins interacting with RAD51 have not been thoroughly investigated in maize. Uncovering ligands of RAD51 would help to understand meiotic recombination and possibly the role of RAD51 in defense. This study used phage display, a tool for discovery of protein-protein interactions, to search for proteins interacting with maize RAD51A1.
Results
Maize RAD51A1 was screened against a random phage library. Eleven short peptide sequences were recovered from 15 phages which bound ZmRAD51A1 in vitro; three sequences were found in multiple successfully binding phages. Nine of these phage interactions were verified in vitro through ELISA and/or dot blotting.
BLAST searches did not reveal any maize proteins which contained the exact sequence of any of the selected phage peptides, although one of the selected phages had a strong alignment (E-value = 0.079) to a binding domain of maize BRCA2. Therefore, we designed 32 additional short peptides using amino acid sequences found in the predicted maize proteome. These peptides were not contained within phages. Of these synthesized peptides, 14 bound to ZmRAD51A1 in a dot blot experiment. These 14 sequences are found in known maize proteins including transcription factors putatively involved in defense.
Conclusions
These results reveal several peptides which bind ZmRAD51A1 and support a potential role for ZmRAD51A1 in transcriptional regulation and plant defense. This study also demonstrates the applicability of phage display to basic science questions, such as the search for binding partners of a known protein, and raises the possibility of an iterated approach to test peptide sequences that closely but imperfectly align with the selected phages.
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11
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Luo Y, Wu H, Huang Q, Rao H, Yu Z, Zhong Z. The Features of BRCA1 and BRCA2 Germline Mutations in Hakka Ovarian Cancer Patients: BRCA1 C.536 A>T Maybe a Founder Mutation in This Population. Int J Gen Med 2022; 15:2773-2786. [PMID: 35300142 PMCID: PMC8922037 DOI: 10.2147/ijgm.s355755] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 03/01/2022] [Indexed: 12/24/2022] Open
Abstract
Objective To investigate the frequencies of BRCA1 and BRCA2 mutations in Chinese Hakka patients with ovarian cancer. Methods The protein coding regions and exon intron boundary regions of the BRCA gene were sequenced using genomic DNA isolated from the lymphocytes of patients with next-generation sequencing. The patients’ family history and clinical records were collected. Results A total of 195 patients with ovarian cancer were included in the study, and 52 distinct variants of the BRCA gene were identified. It was found that 64 patients (64/195, 32.8%) had BRCA gene mutations, including 32 patients (50.0%) with BRCA1 mutation, 27 patients (42.2%) with BRCA2 mutation, and 5 patients (7.8%) with both mutations. Furthermore, 22 pathogenic mutations were detected in 26 patients, 2 likely pathogenic variants in 2 patients, 12 variants of uncertain significance in 20 patients, and 16 likely benign variants in 24 patients. The mutations were mainly found to occur in exons 8, 14, and 17 of BRCA1 and exons 10, 11, 14, and 15 of BRCA2. The results showed that the BRCA genes possess different mutation hotspots in different ethnic groups. In addition, recurrent mutations were noted in many patients. BRCA1 c.536 A>T, considered a founder mutation, was identified in 10 patients (15.63%, 10/64), followed by BRCA1 c.2635 G>T (6.25%, 4/64) and BRCA2 c.2566 T>C (6.25%, 4/64). Conclusion The BRCA1 c.536 A>T could be considered to be a founder mutation in this ovarian cancer population. This recurrent BRCA1 mutation has rarely been observed in other ethnic groups. Our findings are expected to provide valuable data for clinical consultation and for designing individualized treatment for ovarian cancer.
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Affiliation(s)
- Yu Luo
- Department of Gynaecology, Meizhou People’s Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou, People’s Republic of China
- Guangdong Provincial Key Laboratory of Precision Medicine and Clinical Translational Research of Hakka Population, Meizhou People’s Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou, People’s Republic of China
| | - Heming Wu
- Guangdong Provincial Key Laboratory of Precision Medicine and Clinical Translational Research of Hakka Population, Meizhou People’s Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou, People’s Republic of China
- Center for Precision Medicine, Meizhou People’s Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou, People’s Republic of China
| | - Qingyan Huang
- Guangdong Provincial Key Laboratory of Precision Medicine and Clinical Translational Research of Hakka Population, Meizhou People’s Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou, People’s Republic of China
- Center for Precision Medicine, Meizhou People’s Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou, People’s Republic of China
| | - Hui Rao
- Guangdong Provincial Key Laboratory of Precision Medicine and Clinical Translational Research of Hakka Population, Meizhou People’s Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou, People’s Republic of China
- Center for Precision Medicine, Meizhou People’s Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou, People’s Republic of China
| | - Zhikang Yu
- Guangdong Provincial Key Laboratory of Precision Medicine and Clinical Translational Research of Hakka Population, Meizhou People’s Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou, People’s Republic of China
- Center for Precision Medicine, Meizhou People’s Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou, People’s Republic of China
- Correspondence: Zhikang Yu; Zhixiong Zhong, Center for Precision Medicine, Guangdong Provincial Key Laboratory of Precision Medicine and Clinical Translational Research of Hakka Population, Meizhou People’s Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, No. 63 Huangtang Road, Meijiang District, Meizhou, 514031, People’s Republic of China, Tel +753-2131-591, Email ;
| | - Zhixiong Zhong
- Guangdong Provincial Key Laboratory of Precision Medicine and Clinical Translational Research of Hakka Population, Meizhou People’s Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou, People’s Republic of China
- Center for Precision Medicine, Meizhou People’s Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou, People’s Republic of China
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12
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Lindenburg LH, Pantelejevs T, Gielen F, Zuazua-Villar P, Butz M, Rees E, Kaminski CF, Downs JA, Hyvönen M, Hollfelder F. Improved RAD51 binders through motif shuffling based on the modularity of BRC repeats. Proc Natl Acad Sci U S A 2021; 118:e2017708118. [PMID: 34772801 PMCID: PMC8727024 DOI: 10.1073/pnas.2017708118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2021] [Indexed: 01/20/2023] Open
Abstract
Exchanges of protein sequence modules support leaps in function unavailable through point mutations during evolution. Here we study the role of the two RAD51-interacting modules within the eight binding BRC repeats of BRCA2. We created 64 chimeric repeats by shuffling these modules and measured their binding to RAD51. We found that certain shuffled module combinations were stronger binders than any of the module combinations in the natural repeats. Surprisingly, the contribution from the two modules was poorly correlated with affinities of natural repeats, with a weak BRC8 repeat containing the most effective N-terminal module. The binding of the strongest chimera, BRC8-2, to RAD51 was improved by -2.4 kCal/mol compared to the strongest natural repeat, BRC4. A crystal structure of RAD51:BRC8-2 complex shows an improved interface fit and an extended β-hairpin in this repeat. BRC8-2 was shown to function in human cells, preventing the formation of nuclear RAD51 foci after ionizing radiation.
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Affiliation(s)
- Laurens H Lindenburg
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
| | - Teodors Pantelejevs
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
| | - Fabrice Gielen
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
- Living Systems Institute, University of Exeter, Exeter EX4 4QD, United Kingdom
| | - Pedro Zuazua-Villar
- Division of Cancer Biology, The Institute of Cancer Research, London SW3 6JB, United Kingdom
| | - Maren Butz
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
| | - Eric Rees
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, United Kingdom
| | - Clemens F Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, United Kingdom
| | - Jessica A Downs
- Division of Cancer Biology, The Institute of Cancer Research, London SW3 6JB, United Kingdom
| | - Marko Hyvönen
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom;
| | - Florian Hollfelder
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom;
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13
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A complex of BRCA2 and PP2A-B56 is required for DNA repair by homologous recombination. Nat Commun 2021; 12:5748. [PMID: 34593815 PMCID: PMC8484605 DOI: 10.1038/s41467-021-26079-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 09/13/2021] [Indexed: 12/12/2022] Open
Abstract
Mutations in the tumour suppressor gene BRCA2 are associated with predisposition to breast and ovarian cancers. BRCA2 has a central role in maintaining genome integrity by facilitating the repair of toxic DNA double-strand breaks (DSBs) by homologous recombination (HR). BRCA2 acts by controlling RAD51 nucleoprotein filament formation on resected single-stranded DNA, but how BRCA2 activity is regulated during HR is not fully understood. Here, we delineate a pathway where ATM and ATR kinases phosphorylate a highly conserved region in BRCA2 in response to DSBs. These phosphorylations stimulate the binding of the protein phosphatase PP2A-B56 to BRCA2 through a conserved binding motif. We show that the phosphorylation-dependent formation of the BRCA2-PP2A-B56 complex is required for efficient RAD51 filament formation at sites of DNA damage and HR-mediated DNA repair. Moreover, we find that several cancer-associated mutations in BRCA2 deregulate the BRCA2-PP2A-B56 interaction and sensitize cells to PARP inhibition. Collectively, our work uncovers PP2A-B56 as a positive regulator of BRCA2 function in HR with clinical implications for BRCA2 and PP2A-B56 mutated cancers.
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14
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Le HP, Heyer WD, Liu J. Guardians of the Genome: BRCA2 and Its Partners. Genes (Basel) 2021; 12:genes12081229. [PMID: 34440403 PMCID: PMC8394001 DOI: 10.3390/genes12081229] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 08/04/2021] [Accepted: 08/06/2021] [Indexed: 12/28/2022] Open
Abstract
The tumor suppressor BRCA2 functions as a central caretaker of genome stability, and individuals who carry BRCA2 mutations are predisposed to breast, ovarian, and other cancers. Recent research advanced our mechanistic understanding of BRCA2 and its various interaction partners in DNA repair, DNA replication support, and DNA double-strand break repair pathway choice. In this review, we discuss the biochemical and structural properties of BRCA2 and examine how these fundamental properties contribute to DNA repair and replication fork stabilization in living cells. We highlight selected BRCA2 binding partners and discuss their role in BRCA2-mediated homologous recombination and fork protection. Improved mechanistic understanding of how BRCA2 functions in genome stability maintenance can enable experimental evidence-based evaluation of pathogenic BRCA2 mutations and BRCA2 pseudo-revertants to support targeted therapy.
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Affiliation(s)
- Hang Phuong Le
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA; (H.P.L.); (W.-D.H.)
| | - Wolf-Dietrich Heyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA; (H.P.L.); (W.-D.H.)
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
| | - Jie Liu
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA; (H.P.L.); (W.-D.H.)
- Correspondence: ; Tel.: +1-530-752-3016
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15
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Zhang G, Zhang J, Zhu Y, Liu H, Shi Y, Mi K, Li M, Zhao Q, Huang Z, Huang J. Association of somatic mutations in BRCA2 BRC domain with chemotherapy sensitivity and survival in high grade serous ovarian cancer. Exp Cell Res 2021; 406:112742. [PMID: 34302857 DOI: 10.1016/j.yexcr.2021.112742] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 06/29/2021] [Accepted: 07/19/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND Mutations at sites crucial for the interaction between RAD51 and BRC domains impair the ability of BRCA2 homologous recombination. We aimed to clarify whether BRCA2 BRC domain-associated mutation correlates with sensibility of platinum-based chemotherapy and survival in high-grade serous ovarian cancer (HGSOC). METHODS We identified BRCA2 BRC domain mutations by sequencing PCR-amplified amplicons of genomic DNA isolated from tumor tissues and peripheral blood leukocytes (PBL)in 113 patients with advanced EOC, and assessed platinum-free interval (PFI), progression-free survival (PFS) and overall survival (OS). RESULTS 21.23% (24 of 113) cases with somatic missense mutation but not germline mutation were identified. Among 24 cases with mutation, 33.3% (8 of 24) cases with nonsense mutation (C-terminal truncation) significantly prolonged median PFI (37 vs 8 months,P = 0.000), PFS (43 vs 14 months, p = 0.000) and OS (56 vs 31 months, P = 0.002); 66.7% (16 of 24) cases with missense mutation also prolonged median PFI (15 vs 8 months, P = 0.044), PFS (21 vs 14 months, P = 0.049) and OS (38 vs 31 months, P = 0.037), compared to those without any mutation. CONCLUSIONS Somatic mutations in BRCA2 BRC domain confer a higher sensitivity to platinum-based therapy and are associated with a favourable survival in HGSOC.
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Affiliation(s)
- Guonan Zhang
- Department of Gynecologic Oncology, Sichuan Cancer Hospital, Chengdu, 610041, PR China
| | - Jie Zhang
- Department of Gynecologic Oncology, Sichuan Cancer Hospital, Chengdu, 610041, PR China
| | - Yi Zhu
- Department of Gynecologic Oncology, Sichuan Cancer Hospital, Chengdu, 610041, PR China; Department of Ultrasound, Sichuan Cancer Hospital, Chengdu, 610041, PR China
| | - Hong Liu
- Department of Gynecologic Oncology, Sichuan Cancer Hospital, Chengdu, 610041, PR China
| | - Yu Shi
- Department of Gynecologic Oncology, Sichuan Cancer Hospital, Chengdu, 610041, PR China
| | - Kun Mi
- Department of Biochemistry & Molecular Biology, Sichuan Cancer Institute, Chengdu, 610041, PR China
| | - Meiying Li
- Department of Biochemistry & Molecular Biology, Sichuan Cancer Institute, Chengdu, 610041, PR China
| | - Qi Zhao
- Department of Biochemistry & Molecular Biology, Sichuan Cancer Institute, Chengdu, 610041, PR China
| | - Ziyi Huang
- Department of Bioinformatics, Basic Medical College of Chongqing Medical University, Chongqing, PR China
| | - Jianming Huang
- Department of Biochemistry & Molecular Biology, Sichuan Cancer Institute, Chengdu, 610041, PR China.
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16
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BRCA2 Promotes Spontaneous Homologous Recombination In Vivo. Cancers (Basel) 2021; 13:cancers13153663. [PMID: 34359565 PMCID: PMC8345144 DOI: 10.3390/cancers13153663] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/12/2021] [Accepted: 07/15/2021] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND BRCA2 is known to be a tumor suppressor involved in homologous recombination repair and presumed to prevent genome instability in normal tissues prior to the development of tumors. Typical assessment of BRCA2 deficiency on the genome involves cell-based models using cancer cells with mixed genetic contexts, but the role in normal tissue in vivo has not been clearly demonstrated. METHODS Using conditional deletion of Brca2 exon 11, the region containing all eight BRC repeats, in the retinal pigment epithelium and the pink-eyed unstable mouse model, we evaluate the frequency of DNA deletion events. RESULTS In the current study, we show that conditional loss of Brca2 exon 11 results in a decreased frequency of spontaneous homologous recombination compared to wild-type mice. Of note, we observe no apparent concomitant increase in events that indicate single-strand annealing by the pink-eyed unstable mouse model. CONCLUSIONS Therefore, our results demonstrate that BRCA2, as expected, is required for high-fidelity homologous recombination DNA repair in normal tissues, here in a tissue undergoing normal proliferation through normal development.
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17
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Julien M, Ghouil R, Petitalot A, Caputo SM, Carreira A, Zinn-Justin S. Intrinsic Disorder and Phosphorylation in BRCA2 Facilitate Tight Regulation of Multiple Conserved Binding Events. Biomolecules 2021; 11:1060. [PMID: 34356684 PMCID: PMC8301801 DOI: 10.3390/biom11071060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 07/09/2021] [Accepted: 07/13/2021] [Indexed: 12/26/2022] Open
Abstract
The maintenance of genome integrity in the cell is an essential process for the accurate transmission of the genetic material. BRCA2 participates in this process at several levels, including DNA repair by homologous recombination, protection of stalled replication forks, and cell division. These activities are regulated and coordinated via cell-cycle dependent modifications. Pathogenic variants in BRCA2 cause genome instability and are associated with breast and/or ovarian cancers. BRCA2 is a very large protein of 3418 amino acids. Most well-characterized variants causing a strong predisposition to cancer are mutated in the C-terminal 700 residues DNA binding domain of BRCA2. The rest of the BRCA2 protein is predicted to be disordered. Interactions involving intrinsically disordered regions (IDRs) remain difficult to identify both using bioinformatics tools and performing experimental assays. However, the lack of well-structured binding sites provides unique functional opportunities for BRCA2 to bind to a large set of partners in a tightly regulated manner. We here summarize the predictive and experimental arguments that support the presence of disorder in BRCA2. We describe how BRCA2 IDRs mediate self-assembly and binding to partners during DNA double-strand break repair, mitosis, and meiosis. We highlight how phosphorylation by DNA repair and cell-cycle kinases regulate these interactions. We finally discuss the impact of cancer-associated variants on the function of BRCA2 IDRs and more generally on genome stability and cancer risk.
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Affiliation(s)
- Manon Julien
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, 91190 Gif-sur-Yvette, France; (M.J.); (R.G.)
- L’Institut de Biologie Intégrative de la Cellule (I2BC), UMR 9198, Paris-Saclay University, 91190 Gif-sur-Yvette, France;
| | - Rania Ghouil
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, 91190 Gif-sur-Yvette, France; (M.J.); (R.G.)
- L’Institut de Biologie Intégrative de la Cellule (I2BC), UMR 9198, Paris-Saclay University, 91190 Gif-sur-Yvette, France;
| | - Ambre Petitalot
- Service de Génétique, Unité de Génétique Constitutionnelle, Institut Curie, 75005 Paris, France; (A.P.); (S.M.C.)
- Institut Curie, Paris Sciences Lettres Research University, 75005 Paris, France
| | - Sandrine M. Caputo
- Service de Génétique, Unité de Génétique Constitutionnelle, Institut Curie, 75005 Paris, France; (A.P.); (S.M.C.)
- Institut Curie, Paris Sciences Lettres Research University, 75005 Paris, France
| | - Aura Carreira
- L’Institut de Biologie Intégrative de la Cellule (I2BC), UMR 9198, Paris-Saclay University, 91190 Gif-sur-Yvette, France;
- Institut Curie, Paris Sciences Lettres Research University, 75005 Paris, France
- Unité Intégrité du Génome, ARN et Cancer, Institut Curie, CNRS UMR3348, 91405 Orsay, France
| | - Sophie Zinn-Justin
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, 91190 Gif-sur-Yvette, France; (M.J.); (R.G.)
- L’Institut de Biologie Intégrative de la Cellule (I2BC), UMR 9198, Paris-Saclay University, 91190 Gif-sur-Yvette, France;
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18
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Ackerson SM, Romney C, Schuck PL, Stewart JA. To Join or Not to Join: Decision Points Along the Pathway to Double-Strand Break Repair vs. Chromosome End Protection. Front Cell Dev Biol 2021; 9:708763. [PMID: 34322492 PMCID: PMC8311741 DOI: 10.3389/fcell.2021.708763] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 06/17/2021] [Indexed: 01/01/2023] Open
Abstract
The regulation of DNA double-strand breaks (DSBs) and telomeres are diametrically opposed in the cell. DSBs are considered one of the most deleterious forms of DNA damage and must be quickly recognized and repaired. Telomeres, on the other hand, are specialized, stable DNA ends that must be protected from recognition as DSBs to inhibit unwanted chromosome fusions. Decisions to join DNA ends, or not, are therefore critical to genome stability. Yet, the processing of telomeres and DSBs share many commonalities. Accordingly, key decision points are used to shift DNA ends toward DSB repair vs. end protection. Additionally, DSBs can be repaired by two major pathways, namely homologous recombination (HR) and non-homologous end joining (NHEJ). The choice of which repair pathway is employed is also dictated by a series of decision points that shift the break toward HR or NHEJ. In this review, we will focus on these decision points and the mechanisms that dictate end protection vs. DSB repair and DSB repair choice.
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Affiliation(s)
- Stephanie M Ackerson
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - Carlan Romney
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - P Logan Schuck
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - Jason A Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
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19
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Lee M, Shorthouse D, Mahen R, Hall BA, Venkitaraman AR. Cancer-causing BRCA2 missense mutations disrupt an intracellular protein assembly mechanism to disable genome maintenance. Nucleic Acids Res 2021; 49:5588-5604. [PMID: 33978741 PMCID: PMC8191791 DOI: 10.1093/nar/gkab308] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 04/11/2021] [Accepted: 04/28/2021] [Indexed: 12/13/2022] Open
Abstract
Cancer-causing missense mutations in the 3418 amino acid BRCA2 breast and ovarian cancer suppressor protein frequently affect a short (∼340 residue) segment in its carboxyl-terminal domain (DBD). Here, we identify a shared molecular mechanism underlying their pathogenicity. Pathogenic BRCA2 missense mutations cluster in the DBD’s helical domain (HD) and OB1-fold motifs, which engage the partner protein DSS1. Pathogenic - but not benign – DBD mutations weaken or abolish DSS1-BRCA2 assembly, provoking mutant BRCA2 oligomers that are excluded from the cell nucleus, and disable DNA repair by homologous DNA recombination (HDR). DSS1 inhibits the intracellular oligomerization of wildtype, but not mutant, forms of BRCA2. Remarkably, DSS1 expression corrects defective HDR in cells bearing pathogenic BRCA2 missense mutants with weakened, but not absent, DSS1 binding. Our findings identify a DSS1-mediated intracellular protein assembly mechanism that is disrupted by cancer-causing BRCA2 missense mutations, and suggest an approach for its therapeutic correction.
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Affiliation(s)
- Miyoung Lee
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - David Shorthouse
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Robert Mahen
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Benjamin A Hall
- 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.,The Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599 & Agency for Science, Technology and Research (A*STAR), 8A Biomedical Grove 138648, Singapore
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20
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Andreassen PR, Seo J, Wiek C, Hanenberg H. Understanding BRCA2 Function as a Tumor Suppressor Based on Domain-Specific Activities in DNA Damage Responses. Genes (Basel) 2021; 12:genes12071034. [PMID: 34356050 PMCID: PMC8307705 DOI: 10.3390/genes12071034] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/23/2021] [Accepted: 06/29/2021] [Indexed: 01/14/2023] Open
Abstract
BRCA2 is an essential genome stability gene that has various functions in cells, including roles in homologous recombination, G2 checkpoint control, protection of stalled replication forks, and promotion of cellular resistance to numerous types of DNA damage. Heterozygous mutation of BRCA2 is associated with an increased risk of developing cancers of the breast, ovaries, pancreas, and other sites, thus BRCA2 acts as a classic tumor suppressor gene. However, understanding BRCA2 function as a tumor suppressor is severely limited by the fact that ~70% of the encoded protein has not been tested or assigned a function in the cellular DNA damage response. Remarkably, even the specific role(s) of many known domains in BRCA2 are not well characterized, predominantly because stable expression of the very large BRCA2 protein in cells, for experimental purposes, is challenging. Here, we review what is known about these domains and the assay systems that are available to study the cellular roles of BRCA2 domains in DNA damage responses. We also list criteria for better testing systems because, ultimately, functional assays for assessing the impact of germline and acquired mutations identified in genetic screens are important for guiding cancer prevention measures and for tailored cancer treatments.
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Affiliation(s)
- Paul R. Andreassen
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA;
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
- Correspondence: ; Tel.: +1-(513)-636-0499
| | - Joonbae Seo
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA;
| | - Constanze Wiek
- Department of Otorhinolaryngology and Head/Neck Surgery, Heinrich Heine University, 40225 Düsseldorf, Germany; (C.W.); (H.H.)
| | - Helmut Hanenberg
- Department of Otorhinolaryngology and Head/Neck Surgery, Heinrich Heine University, 40225 Düsseldorf, Germany; (C.W.); (H.H.)
- Department of Pediatrics III, Children’s Hospital, University of Duisburg-Essen, 45122 Essen, Germany
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21
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Fanale D, Fiorino A, Incorvaia L, Dimino A, Filorizzo C, Bono M, Cancelliere D, Calò V, Brando C, Corsini LR, Sciacchitano R, Magrin L, Pivetti A, Pedone E, Madonia G, Cucinella A, Badalamenti G, Russo A, Bazan V. Prevalence and Spectrum of Germline BRCA1 and BRCA2 Variants of Uncertain Significance in Breast/Ovarian Cancer: Mysterious Signals From the Genome. Front Oncol 2021; 11:682445. [PMID: 34178674 PMCID: PMC8226162 DOI: 10.3389/fonc.2021.682445] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 05/25/2021] [Indexed: 12/26/2022] Open
Abstract
About 10–20% of breast/ovarian (BC/OC) cancer patients undergoing germline BRCA1/2 genetic testing have been shown to harbor Variants of Uncertain Significance (VUSs). Since little is known about the prevalence of germline BRCA1/2 VUS in Southern Italy, our study aimed at describing the spectrum of these variants detected in BC/OC patients in order to improve the identification of potentially high-risk BRCA variants helpful in patient clinical management. Eight hundred and seventy-four BC or OC patients, enrolled from October 2016 to December 2020 at the “Sicilian Regional Center for the Prevention, Diagnosis and Treatment of Rare and Heredo-Familial Tumors” of University Hospital Policlinico “P. Giaccone” of Palermo, were genetically tested for germline BRCA1/2 variants through Next-Generation Sequencing analysis. The mutational screening showed that 639 (73.1%) out of 874 patients were BRCA-w.t., whereas 67 (7.7%) were carriers of germline BRCA1/2 VUSs, and 168 (19.2%) harbored germline BRCA1/2 pathogenic/likely pathogenic variants. Our analysis revealed the presence of 59 different VUSs detected in 67 patients, 46 of which were affected by BC and 21 by OC. Twenty-one (35.6%) out of 59 variants were located on BRCA1 gene, whereas 38 (64.4%) on BRCA2. We detected six alterations in BRCA1 and two in BRCA2 with unclear interpretation of clinical significance. Familial anamnesis of a patient harboring the BRCA1-c.3367G>T suggests for this variant a potential of pathogenicity, therefore it should be carefully investigated. Understanding clinical significance of germline BRCA1/2 VUS could improve, in future, the identification of potentially high-risk variants useful for clinical management of BC or OC patients and family members.
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Affiliation(s)
- Daniele Fanale
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Alessia Fiorino
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Lorena Incorvaia
- Department of Biomedicine, Neuroscience and Advanced Diagnostics (Bi.N.D.), Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Alessandra Dimino
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Clarissa Filorizzo
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Marco Bono
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Daniela Cancelliere
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Valentina Calò
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Chiara Brando
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Lidia Rita Corsini
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Roberta Sciacchitano
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Luigi Magrin
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Alessia Pivetti
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Erika Pedone
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Giorgio Madonia
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Alessandra Cucinella
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Giuseppe Badalamenti
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Antonio Russo
- Department of Surgical, Oncological and Oral Sciences, Section of Medical Oncology, University of Palermo, Palermo, Italy
| | - Viviana Bazan
- Department of Biomedicine, Neuroscience and Advanced Diagnostics (Bi.N.D.), Section of Medical Oncology, University of Palermo, Palermo, Italy
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22
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Argunhan B, Iwasaki H, Tsubouchi H. Post-translational modification of factors involved in homologous recombination. DNA Repair (Amst) 2021; 104:103114. [PMID: 34111757 DOI: 10.1016/j.dnarep.2021.103114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 03/29/2021] [Accepted: 03/31/2021] [Indexed: 02/04/2023]
Abstract
DNA is the molecule that stores the chemical instructions necessary for life and its stability is therefore of the utmost importance. Despite this, DNA is damaged by both exogenous and endogenous factors at an alarming frequency. The most severe type of DNA damage is a double-strand break (DSB), in which a scission occurs in both strands of the double helix, effectively dividing a single normal chromosome into two pathological chromosomes. Homologous recombination (HR) is a universal DSB repair mechanism that solves this problem by identifying another region of the genome that shares high sequence similarity with the DSB site and using it as a template for repair. Rad51 possess the enzymatic activity that is essential for this repair but several auxiliary factors are required for Rad51 to fulfil its function. It is becoming increasingly clear that many HR factors are subjected to post-translational modification. Here, we review what is known about how these modifications affect HR. We first focus on cases where there is experimental evidence to support a function for the modification, then discuss speculative cases where a function can be inferred. Finally, we contemplate why such modifications might be necessary.
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Affiliation(s)
- Bilge Argunhan
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan.
| | - Hiroshi Iwasaki
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan; School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Hideo Tsubouchi
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan; School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan
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23
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Jensen RB, Rothenberg E. Preserving genome integrity in human cells via DNA double-strand break repair. Mol Biol Cell 2021; 31:859-865. [PMID: 32286930 PMCID: PMC7185975 DOI: 10.1091/mbc.e18-10-0668] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The efficient maintenance of genome integrity in the face of cellular stress is vital to protect against human diseases such as cancer. DNA replication, chromatin dynamics, cellular signaling, nuclear architecture, cell cycle checkpoints, and other cellular activities contribute to the delicate spatiotemporal control that cells utilize to regulate and maintain genome stability. This perspective will highlight DNA double-strand break (DSB) repair pathways in human cells, how DNA repair failures can lead to human disease, and how PARP inhibitors have emerged as a novel clinical therapy to treat homologous recombination-deficient tumors. We briefly discuss how failures in DNA repair produce a permissive genetic environment in which preneoplastic cells evolve to reach their full tumorigenic potential. Finally, we conclude that an in-depth understanding of DNA DSB repair pathways in human cells will lead to novel therapeutic strategies to treat cancer and potentially other human diseases.
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Affiliation(s)
- Ryan B Jensen
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520-8040
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016
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24
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Jimenez-Sainz J, Jensen RB. Imprecise Medicine: BRCA2 Variants of Uncertain Significance (VUS), the Challenges and Benefits to Integrate a Functional Assay Workflow with Clinical Decision Rules. Genes (Basel) 2021; 12:genes12050780. [PMID: 34065235 PMCID: PMC8161351 DOI: 10.3390/genes12050780] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/14/2021] [Accepted: 05/18/2021] [Indexed: 12/20/2022] Open
Abstract
Pathological mutations in homology-directed repair (HDR) genes impact both future cancer risk and therapeutic options for patients. HDR is a high-fidelity DNA repair pathway for resolving DNA double-strand breaks throughout the genome. BRCA2 is an essential protein that mediates the loading of RAD51 onto resected DNA breaks, a key step in HDR. Germline mutations in BRCA2 are associated with an increased risk for breast, ovarian, prostate, and pancreatic cancer. Clinical findings of germline or somatic BRCA2 mutations in tumors suggest treatment with platinum agents or PARP inhibitors. However, when genetic analysis reveals a variant of uncertain significance (VUS) in the BRCA2 gene, precision medicine-based decisions become complex. VUS are genetic changes with unknown pathological impact. Current statistics indicate that between 10–20% of BRCA sequencing results are VUS, and of these, more than 50% are missense mutations. Functional assays to determine the pathological outcome of VUS are urgently needed to provide clinical guidance regarding cancer risk and treatment options. In this review, we provide a brief overview of BRCA2 functions in HDR, describe how BRCA2 VUS are currently assessed in the clinic, and how genetic and biochemical functional assays could be integrated into the clinical decision process. We suggest a multi-step workflow composed of robust and accurate functional assays to correctly evaluate the potential pathogenic or benign nature of BRCA2 VUS. Success in this precision medicine endeavor will offer actionable information to patients and their physicians.
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Affiliation(s)
- Judit Jimenez-Sainz
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
- Correspondence: (J.J.-S.); (R.B.J.); Tel.:+1-203-737-6456 (R.B.J.)
| | - Ryan B. Jensen
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Pathology, Yale University School of Medicine, New Haven, CT 06520, USA
- Correspondence: (J.J.-S.); (R.B.J.); Tel.:+1-203-737-6456 (R.B.J.)
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25
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Carver A, Zhang X. Rad51 filament dynamics and its antagonistic modulators. Semin Cell Dev Biol 2021; 113:3-13. [PMID: 32631783 DOI: 10.1016/j.semcdb.2020.06.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 06/10/2020] [Accepted: 06/20/2020] [Indexed: 02/07/2023]
Abstract
Rad51 recombinase is the central player in homologous recombination, the faithful repair pathway for double-strand breaks and key event during meiosis. Rad51 forms nucleoprotein filaments on single-stranded DNA, exposed by a double-strand break. These filaments are responsible for homology search and strand invasion, which lead to homology-directed repair. Due to its central roles in DNA repair and genome stability, Rad51 is modulated by multiple factors and post-translational modifications. In this review, we summarize our current understanding of the dynamics of Rad51 filaments, the roles of other factors and their modes of action in modulating key stages of Rad51 filaments: formation, stability and disassembly.
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Affiliation(s)
- Alexander Carver
- Section of Structural Biology, Department of Infectious Diseases, Sir Alexander Fleming Building, Imperial College London, SW7 2AZ, UK
| | - Xiaodong Zhang
- Section of Structural Biology, Department of Infectious Diseases, Sir Alexander Fleming Building, Imperial College London, SW7 2AZ, UK.
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26
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Tye S, Ronson GE, Morris JR. A fork in the road: Where homologous recombination and stalled replication fork protection part ways. Semin Cell Dev Biol 2021; 113:14-26. [PMID: 32653304 PMCID: PMC8082280 DOI: 10.1016/j.semcdb.2020.07.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/06/2020] [Accepted: 07/06/2020] [Indexed: 12/14/2022]
Abstract
In response to replication hindrances, DNA replication forks frequently stall and are remodelled into a four-way junction. In such a structure the annealed nascent strand is thought to resemble a DNA double-strand break and remodelled forks are vulnerable to nuclease attack by MRE11 and DNA2. Proteins that promote the recruitment, loading and stabilisation of RAD51 onto single-stranded DNA for homology search and strand exchange in homologous recombination (HR) repair and inter-strand cross-link repair also act to set up RAD51-mediated protection of nascent DNA at stalled replication forks. However, despite the similarities of these pathways, several lines of evidence indicate that fork protection is not simply analogous to the RAD51 loading step of HR. Protection of stalled forks not only requires separate functions of a number of recombination proteins, but also utilises nucleases important for the resection steps of HR in alternative ways. Here we discuss how fork protection arises and how its differences with HR give insights into the differing contexts of these two pathways.
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Affiliation(s)
- Stephanie Tye
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, SW7 2AZ, UK
| | - George E Ronson
- University of Birmingham, College of Medical Dental Schools, Institute of Cancer and Genomics Sciences, Birmingham Centre for Genome Biology, Vincent Drive, Edgbaston, Birmingham, B15 2TT, UK
| | - Joanna R Morris
- University of Birmingham, College of Medical Dental Schools, Institute of Cancer and Genomics Sciences, Birmingham Centre for Genome Biology, Vincent Drive, Edgbaston, Birmingham, B15 2TT, UK.
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27
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Mouse Models for Deciphering the Impact of Homologous Recombination on Tumorigenesis. Cancers (Basel) 2021; 13:cancers13092083. [PMID: 33923105 PMCID: PMC8123484 DOI: 10.3390/cancers13092083] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 12/15/2022] Open
Abstract
Homologous recombination (HR) is a fundamental evolutionarily conserved process that plays prime role(s) in genome stability maintenance through DNA repair and through the protection and resumption of arrested replication forks. Many HR genes are deregulated in cancer cells. Notably, the breast cancer genes BRCA1 and BRCA2, two important HR players, are the most frequently mutated genes in familial breast and ovarian cancer. Transgenic mice constitute powerful tools to unravel the intricate mechanisms controlling tumorigenesis in vivo. However, the genes central to HR are essential in mammals, and their knockout leads to early embryonic lethality in mice. Elaborated strategies have been developed to overcome this difficulty, enabling one to analyze the consequences of HR disruption in vivo. In this review, we first briefly present the molecular mechanisms of HR in mammalian cells to introduce each factor in the HR process. Then, we present the different mouse models of HR invalidation and the consequences of HR inactivation on tumorigenesis. Finally, we discuss the use of mouse models for the development of targeted cancer therapies as well as perspectives on the future potential for understanding the mechanisms of HR inactivation-driven tumorigenesis in vivo.
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28
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Li Q, Engebrecht J. BRCA1 and BRCA2 Tumor Suppressor Function in Meiosis. Front Cell Dev Biol 2021; 9:668309. [PMID: 33996823 PMCID: PMC8121103 DOI: 10.3389/fcell.2021.668309] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 03/19/2021] [Indexed: 12/12/2022] Open
Abstract
Meiosis is a specialized cell cycle that results in the production of haploid gametes for sexual reproduction. During meiosis, homologous chromosomes are connected by chiasmata, the physical manifestation of crossovers. Crossovers are formed by the repair of intentionally induced double strand breaks by homologous recombination and facilitate chromosome alignment on the meiotic spindle and proper chromosome segregation. While it is well established that the tumor suppressors BRCA1 and BRCA2 function in DNA repair and homologous recombination in somatic cells, the functions of BRCA1 and BRCA2 in meiosis have received less attention. Recent studies in both mice and the nematode Caenorhabditis elegans have provided insight into the roles of these tumor suppressors in a number of meiotic processes, revealing both conserved and organism-specific functions. BRCA1 forms an E3 ubiquitin ligase as a heterodimer with BARD1 and appears to have regulatory roles in a number of key meiotic processes. BRCA2 is a very large protein that plays an intimate role in homologous recombination. As women with no indication of cancer but carrying BRCA mutations show decreased ovarian reserve and accumulated oocyte DNA damage, studies in these systems may provide insight into why BRCA mutations impact reproductive success in addition to their established roles in cancer.
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Affiliation(s)
- Qianyan Li
- Department of Molecular and Cellular Biology, and Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California, Davis, Davis, CA, United States
| | - JoAnne Engebrecht
- Department of Molecular and Cellular Biology, and Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California, Davis, Davis, CA, United States
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29
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Ghatnatti V, Vastrad B, Patil S, Vastrad C, Kotturshetti I. Identification of potential and novel target genes in pituitary prolactinoma by bioinformatics analysis. AIMS Neurosci 2021; 8:254-283. [PMID: 33709028 PMCID: PMC7940115 DOI: 10.3934/neuroscience.2021014] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 01/29/2021] [Indexed: 02/05/2023] Open
Abstract
Pituitary prolactinoma is one of the most complicated and fatally pathogenic pituitary adenomas. Therefore, there is an urgent need to improve our understanding of the underlying molecular mechanism that drives the initiation, progression, and metastasis of pituitary prolactinoma. The aim of the present study was to identify the key genes and signaling pathways associated with pituitary prolactinoma using bioinformatics analysis. Transcriptome microarray dataset GSE119063 was downloaded from Gene Expression Omnibus (GEO) database. Limma package in R software was used to screen DEGs. Pathway and Gene ontology (GO) enrichment analysis were conducted to identify the biological role of DEGs. A protein-protein interaction (PPI) network was constructed and analyzed by using HIPPIE database and Cytoscape software. Module analyses was performed. In addition, a target gene-miRNA regulatory network and target gene-TF regulatory network were constructed by using NetworkAnalyst and Cytoscape software. Finally, validation of hub genes by receiver operating characteristic (ROC) curve analysis. A total of 989 DEGs were identified, including 461 up regulated genes and 528 down regulated genes. Pathway enrichment analysis showed that the DEGs were significantly enriched in the retinoate biosynthesis II, signaling pathways regulating pluripotency of stem cells, ALK2 signaling events, vitamin D3 biosynthesis, cell cycle and aurora B signaling. Gene Ontology (GO) enrichment analysis showed that the DEGs were significantly enriched in the sensory organ morphogenesis, extracellular matrix, hormone activity, nuclear division, condensed chromosome and microtubule binding. In the PPI network and modules, SOX2, PRSS45, CLTC, PLK1, B4GALT6, RUNX1 and GTSE1 were considered as hub genes. In the target gene-miRNA regulatory network and target gene-TF regulatory network, LINC00598, SOX4, IRX1 and UNC13A were considered as hub genes. Using integrated bioinformatics analysis, we identified candidate genes in pituitary prolactinoma, which might improve our understanding of the molecular mechanisms of pituitary prolactinoma.
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Affiliation(s)
- Vikrant Ghatnatti
- Department of Endocrinology, J N Medical College, Belagavi and KLE Academy of Higher Education & Research 590010, Karnataka, India
| | - Basavaraj Vastrad
- Department of Biochemistry, Basaveshwar College of Pharmacy, Gadag, Karnataka 582103, India
| | - Swetha Patil
- Department of Obstetrics and Gynaecology, J N Medical College, Belagavi and KLE Academy of Higher Education & Research 590010, Karnataka, India
| | - Chanabasayya Vastrad
- Biostatistics and Bioinformatics, Chanabasava Nilaya, Bharthinagar, Dharwad 580001, Karanataka, India
| | - Iranna Kotturshetti
- Department of Ayurveda, Rajiv Gandhi Education Society's Ayurvedic Medical College, Ron 562209, Karanataka, India
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30
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Scott DE, Francis-Newton NJ, Marsh ME, Coyne AG, Fischer G, Moschetti T, Bayly AR, Sharpe TD, Haas KT, Barber L, Valenzano CR, Srinivasan R, Huggins DJ, Lee M, Emery A, Hardwick B, Ehebauer M, Dagostin C, Esposito A, Pellegrini L, Perrior T, McKenzie G, Blundell TL, Hyvönen M, Skidmore J, Venkitaraman AR, Abell C. A small-molecule inhibitor of the BRCA2-RAD51 interaction modulates RAD51 assembly and potentiates DNA damage-induced cell death. Cell Chem Biol 2021; 28:835-847.e5. [PMID: 33662256 PMCID: PMC8219027 DOI: 10.1016/j.chembiol.2021.02.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 12/18/2020] [Accepted: 02/03/2021] [Indexed: 12/11/2022]
Abstract
BRCA2 controls RAD51 recombinase during homologous DNA recombination (HDR) through eight evolutionarily conserved BRC repeats, which individually engage RAD51 via the motif Phe-x-x-Ala. Using structure-guided molecular design, templated on a monomeric thermostable chimera between human RAD51 and archaeal RadA, we identify CAM833, a 529 Da orthosteric inhibitor of RAD51:BRC with a Kd of 366 nM. The quinoline of CAM833 occupies a hotspot, the Phe-binding pocket on RAD51 and the methyl of the substituted α-methylbenzyl group occupies the Ala-binding pocket. In cells, CAM833 diminishes formation of damage-induced RAD51 nuclear foci; inhibits RAD51 molecular clustering, suppressing extended RAD51 filament assembly; potentiates cytotoxicity by ionizing radiation, augmenting 4N cell-cycle arrest and apoptotic cell death and works with poly-ADP ribose polymerase (PARP)1 inhibitors to suppress growth in BRCA2-wildtype cells. Thus, chemical inhibition of the protein-protein interaction between BRCA2 and RAD51 disrupts HDR and potentiates DNA damage-induced cell death, with implications for cancer therapy.
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Affiliation(s)
- Duncan E Scott
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Nicola J Francis-Newton
- Medical Research Council Cancer Unit, University of Cambridge, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 0XZ, UK
| | - May E Marsh
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Anthony G Coyne
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Gerhard Fischer
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Tommaso Moschetti
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Andrew R Bayly
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Timothy D Sharpe
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Kalina T Haas
- Medical Research Council Cancer Unit, University of Cambridge, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 0XZ, UK
| | - Lorraine Barber
- Medical Research Council Cancer Unit, University of Cambridge, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 0XZ, UK
| | - Chiara R Valenzano
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Rajavel Srinivasan
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - David J Huggins
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK; Medical Research Council Cancer Unit, University of Cambridge, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 0XZ, UK
| | - Miyoung Lee
- Medical Research Council Cancer Unit, University of Cambridge, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 0XZ, UK
| | - Amy Emery
- Medical Research Council Cancer Unit, University of Cambridge, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 0XZ, UK
| | - Bryn Hardwick
- Medical Research Council Cancer Unit, University of Cambridge, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 0XZ, UK
| | - Matthias Ehebauer
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Claudio Dagostin
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Alessandro Esposito
- Medical Research Council Cancer Unit, University of Cambridge, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 0XZ, UK
| | - Luca Pellegrini
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Trevor Perrior
- Excellium Consulting, Brook Farm Barn, Lackford, Bury St Edmunds IP28 6HL, UK
| | - Grahame McKenzie
- Medical Research Council Cancer Unit, University of Cambridge, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 0XZ, UK
| | - Tom L Blundell
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Marko Hyvönen
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK.
| | - John Skidmore
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Ashok R Venkitaraman
- Medical Research Council Cancer Unit, University of Cambridge, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 0XZ, UK.
| | - Chris Abell
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
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Fu R, Wang C, Shen H, Zhang J, Higgins JD, Liang W. Rice OsBRCA2 Is Required for DNA Double-Strand Break Repair in Meiotic Cells. FRONTIERS IN PLANT SCIENCE 2020; 11:600820. [PMID: 33304374 PMCID: PMC7701097 DOI: 10.3389/fpls.2020.600820] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 10/27/2020] [Indexed: 06/06/2023]
Abstract
The mammalian BREAST CANCER 2 (BRCA2) gene is a tumor suppressor that plays a crucial role in DNA repair and homologous recombination (HR). Here, we report the identification and characterization of OsBRCA2, the rice orthologue of human BRCA2. Osbrca2 mutant plants exhibit normal vegetative growth but experience complete male and female sterility as a consequence of severe meiotic defects. Pairing, synapsis and recombination are impaired in osbrca2 male meiocytes, leading to chromosome entanglements and fragmentation. In the absence of OsBRCA2, localization to the meiotic chromosome axes of the strand-invasion proteins OsRAD51 and OsDMC1 is severely reduced and in vitro OsBRCA2 directly interacts with OsRAD51 and OsDMC1. These results indicate that OsBRCA2 is essential for facilitating the loading of OsRAD51 and OsDMC1 onto resected ends of programmed double-strand breaks (DSB) during meiosis to promote single-end invasions of homologous chromosomes and accurate recombination. In addition, treatment of osbrca2-1 seedlings with mitomycin C (MMC) led to hypersensitivity. As MMC is a genotoxic agent that creates DNA lesions in the somatic cells that can only be repaired by HR, these results suggest that OsBRCA2 has a conserved role in DSB repair and HR in rice.
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Affiliation(s)
- Ruifeng Fu
- Joint International Research Laboratory of Metabolic & Developmental Sciences, Shanghai Jiao Tong University–University of Adelaide Joint Centre for Agriculture and Health, State Key Laboratory of Hybrid Rice, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Chong Wang
- Joint International Research Laboratory of Metabolic & Developmental Sciences, Shanghai Jiao Tong University–University of Adelaide Joint Centre for Agriculture and Health, State Key Laboratory of Hybrid Rice, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Hongyu Shen
- Joint International Research Laboratory of Metabolic & Developmental Sciences, Shanghai Jiao Tong University–University of Adelaide Joint Centre for Agriculture and Health, State Key Laboratory of Hybrid Rice, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Jie Zhang
- Joint International Research Laboratory of Metabolic & Developmental Sciences, Shanghai Jiao Tong University–University of Adelaide Joint Centre for Agriculture and Health, State Key Laboratory of Hybrid Rice, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - James D. Higgins
- Department of Genetics and Genome Biology, University of Leicester,Leicester, United Kingdom
| | - Wanqi Liang
- Joint International Research Laboratory of Metabolic & Developmental Sciences, Shanghai Jiao Tong University–University of Adelaide Joint Centre for Agriculture and Health, State Key Laboratory of Hybrid Rice, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
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32
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Sidhu A, Grosbart M, Sánchez H, Verhagen B, van der Zon NLL, Ristić D, van Rossum-Fikkert SE, Wyman C. Conformational flexibility and oligomerization of BRCA2 regions induced by RAD51 interaction. Nucleic Acids Res 2020; 48:9649-9659. [PMID: 32785644 PMCID: PMC7515699 DOI: 10.1093/nar/gkaa648] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 07/15/2020] [Accepted: 08/07/2020] [Indexed: 12/01/2022] Open
Abstract
BRCA2 is a key breast cancer associated protein that is predicted to have interspersed regions of intrinsic disorder. Intrinsic disorder coupled with large size likely allows BRCA2 to sample a broad range of conformational space. We expect that the resulting dynamic arrangements of BRCA2 domains are a functionally important aspect of its role in homologous recombination DNA repair. To determine the architectural organization and the associated conformational landscape of BRCA2, we used scanning force microscopy based single molecule analyses to map the flexible regions of the protein and characterize which regions influence oligomerization. We show that the N- and the C-terminal regions are the main flexible regions. Both of these regions also influence BRCA2 oligomerization and interaction with RAD51. In the central Brc repeat region, Brc 1–4 and Brc 5–8 contribute synergistically to BRCA2 interaction with RAD51. We also analysed several single amino acid changes that are potentially clinically relevant and found one, the variant of F1524V, which disrupts key interactions and alters the conformational landscape of the protein. We describe the overall conformation spectrum of BRCA2, which suggests that dynamic structural transitions are key features of its biological function, maintaining genomic stability.
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Affiliation(s)
- Arshdeep Sidhu
- Department of Molecular Genetics, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.,Department of Radiation Oncology and Cancer Genomics Center, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Małgorzata Grosbart
- Department of Molecular Genetics, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Humberto Sánchez
- Department of Bionanoscience, Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, 2628 CJ Delft, The Netherlands
| | - Bram Verhagen
- Department of Molecular Genetics, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Nick L L van der Zon
- Department of Molecular Genetics, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Dejan Ristić
- Department of Molecular Genetics, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | | | - Claire Wyman
- Department of Molecular Genetics, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.,Department of Radiation Oncology and Cancer Genomics Center, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
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33
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Sadeghi F, Asgari M, Matloubi M, Ranjbar M, Karkhaneh Yousefi N, Azari T, Zaki-Dizaji M. Molecular contribution of BRCA1 and BRCA2 to genome instability in breast cancer patients: review of radiosensitivity assays. Biol Proced Online 2020; 22:23. [PMID: 33013205 PMCID: PMC7528506 DOI: 10.1186/s12575-020-00133-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 08/04/2020] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND DNA repair pathways, cell cycle arrest checkpoints, and cell death induction are present in cells to process DNA damage and prevent genomic instability caused by various extrinsic and intrinsic ionizing factors. Mutations in the genes involved in these pathways enhances the ionizing radiation sensitivity, reduces the individual's capacity to repair DNA damages, and subsequently increases susceptibility to tumorigenesis. BODY BRCA1 and BRCA2 are two highly penetrant genes involved in the inherited breast cancer and contribute to different DNA damage pathways and cell cycle and apoptosis cascades. Mutations in these genes have been associated with hypersensitivity and genetic instability as well as manifesting severe radiotherapy complications in breast cancer patients. The genomic instability and DNA repair capacity of breast cancer patients with BRCA1/2 mutations have been analyzed in different studies using a variety of assays, including micronucleus assay, comet assay, chromosomal assay, colony-forming assay, γ -H2AX and 53BP1 biomarkers, and fluorescence in situ hybridization. The majority of studies confirmed the enhanced spontaneous & radiation-induced radiosensitivity of breast cancer patients compared to healthy controls. Using G2 micronucleus assay and G2 chromosomal assay, most studies have reported the lymphocyte of healthy carriers with BRCA1 mutation are hypersensitive to invitro ionizing radiation compared to non-carriers without a history of breast cancer. However, it seems this approach is not likely to be useful to distinguish the BRCA carriers from non-carrier with familial history of breast cancer. CONCLUSION In overall, breast cancer patients are more radiosensitive compared to healthy control; however, inconsistent results exist about the ability of current radiosensitive techniques in screening BRCA1/2 carriers or those susceptible to radiotherapy complications. Therefore, developing further radiosensitivity assay is still warranted to evaluate the DNA repair capacity of individuals with BRCA1/2 mutations and serve as a predictive factor for increased risk of cancer mainly in the relatives of breast cancer patients. Moreover, it can provide more evidence about who is susceptible to manifest severe complication after radiotherapy.
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Affiliation(s)
- Fatemeh Sadeghi
- Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
- Digestive Diseases Research Institute, Digestive Oncology Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Marzieh Asgari
- Rheumatology Research Center, Tehran University of Medical Sciences, Shariati Hospital, Kargar Ave, Tehran, Iran
| | - Mojdeh Matloubi
- Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Maral Ranjbar
- Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Nahid Karkhaneh Yousefi
- Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran
| | - Tahereh Azari
- Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Majid Zaki-Dizaji
- Legal Medicine Research Center, Legal Medicine Organization, Tehran, Iran
- Research Center for Immunodeficiencies, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran
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34
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Chen X, Peng F, Ji Y, Xiang H, Wang X, Liu T, Wang H, Han Y, Wang C, Zhang Y, Kong X, Lang JY. Brca2 deficiency drives gastrointestinal tumor formation and is selectively inhibited by mitomycin C. Cell Death Dis 2020; 11:812. [PMID: 32980867 PMCID: PMC7519908 DOI: 10.1038/s41419-020-03013-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 09/13/2020] [Accepted: 09/15/2020] [Indexed: 12/24/2022]
Abstract
BRCA2 is crucial for repairing DNA double-strand breaks with high fidelity, and loss of BRCA2 increases the risks of developing breast and ovarian cancers. Herein, we show that BRCA2 is inactively mutated in 10% of gastric and 7% of colorectal adenocarcinomas, and that this inactivation is significantly correlated with microsatellite instability. Villin-driven Brca2 depletion promotes mouse gastrointestinal tumor formation when genome instability is increased. Whole-genome screening data showed that these BRCA2 monoallelic and biallelic mutant tumors were selectively inhibited by mitomycin C. Mechanistically, mitomycin C provoked double-strand breaks in cancer cells that often recruit wild-type BRCA2 for repair; the failure to repair double-strand breaks caused cell-cycle arrest at the S phase and p53-mediated cell apoptosis of BRCA2 monoallelic and biallelic mutant tumor cells. Our study unveils the role of BRCA2 loss in the development of gastrointestinal tumors and provides a potential therapeutic strategy to eliminate BRCA2 monoallelic and biallelic mutant tumors through mitomycin C.
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Affiliation(s)
- Xiaomin Chen
- CAS_Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 200031, Shanghai, China
| | - Fangfei Peng
- CAS_Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 200031, Shanghai, China
| | - Yan Ji
- Bioinformatics Core, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200031, Shanghai, China
| | - Honggang Xiang
- Department of General Surgery, Pudong New Area People's Hospital affiliated to Shanghai University of Medicine & Health Science, 201299, Shanghai, China
| | - Xiang Wang
- CAS_Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 200031, Shanghai, China
| | - Tingting Liu
- CAS_Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 200031, Shanghai, China
| | - Heng Wang
- CAS_Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 200031, Shanghai, China
| | - Yumin Han
- CAS_Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 200031, Shanghai, China
| | - Changxu Wang
- CAS_Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 200031, Shanghai, China
| | - Yongfeng Zhang
- CAS_Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 200031, Shanghai, China
| | - Xiangyin Kong
- CAS_Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 200031, Shanghai, China
| | - Jing-Yu Lang
- CAS_Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 200031, Shanghai, China.
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35
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Le HP, Ma X, Vaquero J, Brinkmeyer M, Guo F, Heyer WD, Liu J. DSS1 and ssDNA regulate oligomerization of BRCA2. Nucleic Acids Res 2020; 48:7818-7833. [PMID: 32609828 PMCID: PMC7641332 DOI: 10.1093/nar/gkaa555] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 06/16/2020] [Accepted: 06/19/2020] [Indexed: 01/27/2023] Open
Abstract
The tumor suppressor BRCA2 plays a key role in initiating homologous recombination by facilitating RAD51 filament formation on single-stranded DNA. The small acidic protein DSS1 is a crucial partner to BRCA2 in this process. In vitro and in cells (1,2), BRCA2 associates into oligomeric complexes besides also existing as monomers. A dimeric structure was further characterized by electron microscopic analysis (3), but the functional significance of the different BRCA2 assemblies remains to be determined. Here, we used biochemistry and electron microscopic imaging to demonstrate that the multimerization of BRCA2 is counteracted by DSS1 and ssDNA. When validating the findings, we identified three self-interacting regions and two types of self-association, the N-to-C terminal and the N-to-N terminal interactions. The N-to-C terminal self-interaction of BRCA2 is sensitive to DSS1 and ssDNA. The N-to-N terminal self-interaction is modulated by ssDNA. Our results define a novel role of DSS1 to regulate BRCA2 in an RPA-independent fashion. Since DSS1 is required for BRCA2 function in recombination, we speculate that the monomeric and oligomeric forms of BRCA2 might be active for different cellular events in recombinational DNA repair and replication fork stabilization.
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Affiliation(s)
- Hang Phuong Le
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA 95616-8665, USA
| | - Xiaoyan Ma
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA 95616-8665, USA
| | - Jorge Vaquero
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA 95616-8665, USA
| | - Megan Brinkmeyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA 95616-8665, USA
| | - Fei Guo
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616-8665, USA
| | - Wolf-Dietrich Heyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA 95616-8665, USA.,Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616-8665, USA
| | - Jie Liu
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA 95616-8665, USA
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36
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Boonen RACM, Vreeswijk MPG, van Attikum H. Functional Characterization of PALB2 Variants of Uncertain Significance: Toward Cancer Risk and Therapy Response Prediction. Front Mol Biosci 2020; 7:169. [PMID: 33195396 PMCID: PMC7525363 DOI: 10.3389/fmolb.2020.00169] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 07/02/2020] [Indexed: 12/12/2022] Open
Abstract
In recent years it has become clear that pathogenic variants in PALB2 are associated with a high risk for breast, ovarian and pancreatic cancer. However, the clinical relevance of variants of uncertain significance (VUS) in PALB2, which are increasingly identified through clinical genetic testing, is unclear. Here we review recent advances in the functional characterization of VUS in PALB2. A combination of assays has been used to assess the impact of PALB2 VUS on its function in DNA repair by homologous recombination, cell cycle regulation and the control of cellular levels of reactive oxygen species (ROS). We discuss the outcome of this comprehensive analysis of PALB2 VUS, which showed that VUS in PALB2’s Coiled-Coil (CC) domain can impair the interaction with BRCA1, whereas VUS in its WD40 domain affect PALB2 protein stability. Accordingly, the CC and WD40 domains of PALB2 represent hotspots for variants that impair PALB2 protein function. We also provide a future perspective on the high-throughput analysis of VUS in PALB2, as well as the functional characterization of variants that affect PALB2 RNA splicing. Finally, we discuss how results from these functional assays can be valuable for predicting cancer risk and responsiveness to cancer therapy, such as treatment with PARP inhibitor- or platinum-based chemotherapy.
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Affiliation(s)
- Rick A C M Boonen
- Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
| | - Maaike P G Vreeswijk
- Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
| | - Haico van Attikum
- Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
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37
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Nguyen DD, Kim EY, Sang PB, Chai W. Roles of OB-Fold Proteins in Replication Stress. Front Cell Dev Biol 2020; 8:574466. [PMID: 33043007 PMCID: PMC7517361 DOI: 10.3389/fcell.2020.574466] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 08/25/2020] [Indexed: 12/20/2022] Open
Abstract
Accurate DNA replication is essential for maintaining genome stability. However, this stability becomes vulnerable when replication fork progression is stalled or slowed - a condition known as replication stress. Prolonged fork stalling can cause DNA damage, leading to genome instabilities. Thus, cells have developed several pathways and a complex set of proteins to overcome the challenge at stalled replication forks. Oligonucleotide/oligosaccharide binding (OB)-fold containing proteins are a group of proteins that play a crucial role in fork protection and fork restart. These proteins bind to single-stranded DNA with high affinity and prevent premature annealing and unwanted nuclease digestion. Among these OB-fold containing proteins, the best studied in eukaryotic cells are replication protein A (RPA) and breast cancer susceptibility protein 2 (BRCA2). Recently, another RPA-like protein complex CTC1-STN1-TEN1 (CST) complex has been found to counter replication perturbation. In this review, we discuss the latest findings on how these OB-fold containing proteins (RPA, BRCA2, CST) cooperate to safeguard DNA replication and maintain genome stability.
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Affiliation(s)
| | | | | | - Weihang Chai
- Department of Cancer Biology, Cardinal Bernardin Cancer Center, Loyola University Chicago Stritch School of Medicine, Maywood, IL, United States
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38
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Symmetric neural progenitor divisions require chromatin-mediated homologous recombination DNA repair by Ino80. Nat Commun 2020; 11:3839. [PMID: 32737294 PMCID: PMC7395731 DOI: 10.1038/s41467-020-17551-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 07/02/2020] [Indexed: 12/12/2022] Open
Abstract
Chromatin regulates spatiotemporal gene expression during neurodevelopment, but it also mediates DNA damage repair essential to proliferating neural progenitor cells (NPCs). Here, we uncover molecularly dissociable roles for nucleosome remodeler Ino80 in chromatin-mediated transcriptional regulation and genome maintenance in corticogenesis. We find that conditional Ino80 deletion from cortical NPCs impairs DNA double-strand break (DSB) repair, triggering p53-dependent apoptosis and microcephaly. Using an in vivo DSB repair pathway assay, we find that Ino80 is selectively required for homologous recombination (HR) DNA repair, which is mechanistically distinct from Ino80 function in YY1-associated transcription. Unexpectedly, sensitivity to loss of Ino80-mediated HR is dependent on NPC division mode: Ino80 deletion leads to unrepaired DNA breaks and apoptosis in symmetric NPC-NPC divisions, but not in asymmetric neurogenic divisions. This division mode dependence is phenocopied following conditional deletion of HR gene Brca2. Thus, distinct modes of NPC division have divergent requirements for Ino80-dependent HR DNA repair.
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39
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Brandsma I, Sato K, van Rossum-Fikkert SE, van Vliet N, Sleddens E, Reuter M, Odijk H, van den Tempel N, Dekkers DHW, Bezstarosti K, Demmers JAA, Maas A, Lebbink J, Wyman C, Essers J, van Gent DC, Baarends WM, Knipscheer P, Kanaar R, Zelensky AN. HSF2BP Interacts with a Conserved Domain of BRCA2 and Is Required for Mouse Spermatogenesis. Cell Rep 2020; 27:3790-3798.e7. [PMID: 31242413 DOI: 10.1016/j.celrep.2019.05.096] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 05/01/2019] [Accepted: 05/23/2019] [Indexed: 12/19/2022] Open
Abstract
The tumor suppressor BRCA2 is essential for homologous recombination (HR), replication fork stability, and DNA interstrand crosslink repair in vertebrates. We identify HSF2BP, a protein previously described as testis specific and not characterized functionally, as an interactor of BRCA2 in mouse embryonic stem cells, where the 2 proteins form a constitutive complex. HSF2BP is transcribed in all cultured human cancer cell lines tested and elevated in some tumor samples. Inactivation of the mouse Hsf2bp gene results in male infertility due to a severe HR defect during spermatogenesis. The BRCA2-HSF2BP interaction is highly evolutionarily conserved and maps to armadillo repeats in HSF2BP and a 68-amino acid region between the BRC repeats and the DNA binding domain of human BRCA2 (Gly2270-Thr2337) encoded by exons 12 and 13. This region of BRCA2 does not harbor known cancer-associated missense mutations and may be involved in the reproductive rather than the tumor-suppressing function of BRCA2.
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Affiliation(s)
- Inger Brandsma
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Koichi Sato
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, 3584 CT Utrecht, the Netherlands
| | - Sari E van Rossum-Fikkert
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands; Department of Radiation Oncology, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Nicole van Vliet
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Esther Sleddens
- Department of Developmental Biology, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Marcel Reuter
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Hanny Odijk
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Nathalie van den Tempel
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Dick H W Dekkers
- Proteomics Center, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Karel Bezstarosti
- Proteomics Center, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Jeroen A A Demmers
- Proteomics Center, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Alex Maas
- Department of Cell Biology, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Joyce Lebbink
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands; Department of Radiation Oncology, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Claire Wyman
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands; Department of Radiation Oncology, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Jeroen Essers
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands; Department of Radiation Oncology, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands; Department of Vascular Surgery, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Dik C van Gent
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Willy M Baarends
- Department of Developmental Biology, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Puck Knipscheer
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, 3584 CT Utrecht, the Netherlands.
| | - Roland Kanaar
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands.
| | - Alex N Zelensky
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands.
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40
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Abstract
Accurate DNA repair and replication are critical for genomic stability and cancer prevention. RAD51 and its gene family are key regulators of DNA fidelity through diverse roles in double-strand break repair, replication stress, and meiosis. RAD51 is an ATPase that forms a nucleoprotein filament on single-stranded DNA. RAD51 has the function of finding and invading homologous DNA sequences to enable accurate and timely DNA repair. Its paralogs, which arose from ancient gene duplications of RAD51, have evolved to regulate and promote RAD51 function. Underscoring its importance, misregulation of RAD51, and its paralogs, is associated with diseases such as cancer and Fanconi anemia. In this review, we focus on the mammalian RAD51 structure and function and highlight the use of model systems to enable mechanistic understanding of RAD51 cellular roles. We also discuss how misregulation of the RAD51 gene family members contributes to disease and consider new approaches to pharmacologically inhibit RAD51.
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Affiliation(s)
- Braulio Bonilla
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA;
| | - Sarah R Hengel
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA;
| | - McKenzie K Grundy
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA;
| | - Kara A Bernstein
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA;
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41
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Liang Z, Hu W, Li S, Wei Z, Zhu Z. Germline BRCA2 Truncating Mutation in Familial Esophageal Squamous Cell Carcinoma: A Case Controlled Study in China. Med Sci Monit 2020; 26:e923926. [PMID: 32579544 PMCID: PMC7331485 DOI: 10.12659/msm.923926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Background Germline mutations of BRCA2 have been reported in various malignancies. We investigated BRCA2 germline mutations in familial clusters with esophageal squamous cell carcinoma (ESCC). Material/Methods We screened the DNA of familial ESCC patients for BRCA2 germline mutations with whole gene sequencing. Multiple BRCA2 mutations including one novel splice variant, c.426-2A>G were identified. Other family members, sporadic ESCC patients, and controls were also assessed for the novel mutation. Results The mutation c.426-2A>G was found in 2 affected ESCC sisters and 7 other family members. The splice variant mutation results in exon 5 skipping with a frame shift leading to a premature stop codon in exon 6 and truncation. Novel mutation tracking ruled out single nucleotide polymorphism (SNP) in 100 chromosomes of healthy individuals. Conclusions BRCA2 germline mutation in ESCC patients may play a role in genetic susceptibility to familial ESCC. Genetic analysis of BRCA2 in patients with familial ESCC could provide opportunities for targeted therapies.
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Affiliation(s)
- Zhong Liang
- Department of Thoracic Surgery, Gansu Provincial Hospital, Lanzhou, Gansu, China (mainland)
| | - Weidong Hu
- Department of Respiration, Gansu Provincial Hospital, Lanzhou, Gansu, China (mainland)
| | - Shuping Li
- Department of Radiotherapy, Gansu Provincial Hospital, Lanzhou, Gansu, China (mainland)
| | - Zhenhong Wei
- Department of Clinical Laboratory, Gansu Provincial Hospital, Lanzhou, Gansu, China (mainland)
| | - Zijiang Zhu
- Department of Thoracic Surgery, Gansu Provincial Hospital, Lanzhou, Gansu, China (mainland)
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42
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Singh AK, Yu X. Tissue-Specific Carcinogens as Soil to Seed BRCA1/2-Mutant Hereditary Cancers. Trends Cancer 2020; 6:559-568. [PMID: 32336659 DOI: 10.1016/j.trecan.2020.03.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 03/05/2020] [Accepted: 03/10/2020] [Indexed: 02/06/2023]
Abstract
Despite their ubiquitous expression, the inheritance of monoallelic germline mutations in breast cancer susceptibility gene type 1 or 2 (BRCA1/2) poses tissue-specific variations in cancer risks and primarily associate with familial breast and ovarian cancers. The molecular basis of this tissue-specific tumor incidence remains unknown and intriguing to cancer researchers. A plethora of recent reports support the idea that several nongenetic factors present in the tissue microenvironment could induce tumors in the mutant BRCA1/2 background. This Opinion article summarizes the recent advances on tissue-specific carcinogens and their complex crosstalk with the compromised DNA repair machinery of BRCA1/2-mutant cells. Finally, we present our perspective on the therapeutic and chemopreventive interpretations of these developments.
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Affiliation(s)
- Anup Kumar Singh
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA
| | - Xiaochun Yu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA.
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43
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Lee A, Moon BI, Kim TH. BRCA1/ BRCA2 Pathogenic Variant Breast Cancer: Treatment and Prevention Strategies. Ann Lab Med 2020; 40:114-121. [PMID: 31650727 PMCID: PMC6822003 DOI: 10.3343/alm.2020.40.2.114] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 08/21/2019] [Accepted: 10/10/2019] [Indexed: 12/24/2022] Open
Abstract
Hereditary breast cancer is known for its strong tendency of inheritance. Most hereditary breast cancers are related to BRCA1/BRCA2 pathogenic variants. The lifelong risk of breast cancer in pathogenic BRCA1 and BRCA2 variant carriers is approximately 65% and 45%, respectively, whereas that of ovarian cancer is estimated to be 39% and 11%, respectively. Therefore, understanding these variants and clinical knowledge on their occurrence in breast cancers and carriers are important. BRCA1 pathogenic variant breast cancer shows more aggressive clinicopathological features than the BRCA2 pathogenic variant breast cancer. Compared with sporadic breast cancer, their prognosis is still debated. Treatments of BRCA1/BRCA2 pathogenic variant breast cancer are similar to those for BRCA-negative breast cancer, mainly including surgery, radiotherapy, and chemotherapy. Recently, various clinical trials have investigated poly (adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitor treatment for advanced-stage BRCA1/BRCA2 pathogenic variant breast cancer. Among the various PARP inhibitors, olaparib and talazoparib, which reached phase III clinical trials, showed improvement of median progression-free survival around three months. Preventive and surveillance strategies for BRCA pathogenic variant breast cancer to reduce cancer recurrence and improve treatment outcomes have recently received increasing attention. In this review, we provide an information on the clinical features of BRCA1/BRCA2 pathogenic variant breast cancer and clinical recommendations for BRCA pathogenic variant carriers, with a focus on treatment and prevention strategies. With this knowledge, clinicians could manage the BRCA1/BRCA2 pathogenic variant breast cancer patients more effectively.
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Affiliation(s)
- Anbok Lee
- Department of Surgery, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
| | - Byung In Moon
- Department of Surgery, Mokdong Hospital, Ewha Womans University College of Medicine, Seoul, Korea
| | - Tae Hyun Kim
- Department of Surgery, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea
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44
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Wu H, Wang Q, Guo X, Liu Q, Zhang Q, Huang Q, Yu Z. Frequency of BRCA1 and BRCA2 Mutations in Individuals with Breast and Ovarian Cancer in a Chinese Hakka Population Using Next-Generation Sequencing. Hum Hered 2020; 84:160-169. [PMID: 32101877 DOI: 10.1159/000505268] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 12/04/2019] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND It is necessary to investigate the frequency of BRCA1 and BRCA2 mutations in Hakka populations due to the variations in breast cancer epidemiology and genetics. METHODS 359 breast cancer patients and 66 ovarian cancer patients were included in this retrospective clinical study. Mutations of BRCA1 and BRCA2 were detected in blood samples by semiconductor sequencing. RESULTS The sensitivity of tumor markers including CEA, CA15-3, CA12-5, and CA199 for screening breast cancer was 16.44, 15.11, 8.44, and 7.56%, the combination of these 4 tumor markers reached the highest sensitivity index (31.11%). For ovarian cancer, the tumor markers were CA12-5 (54.05%), HE-4 (54.05%), CA72-4 (51.35%), and CEA (2.70%) in order of decreasing sensitivity. Moreover, the combination of these 4 tumor markers has the best sensitivity (75.68%) for screening ovarian cancer. In breast cancer patients, we found 5 (1.39%) patients with mutations in BRCA1, 13 (3.62%) mutations in BRCA2, and the total carrier rate is 5.01% (18/359). For ovarian cancer patients, the corresponding results were 3 (4.54%) mutations, 2 (3.03%) mutations, and 7.58% (5/66), respectively. The proportion of BRCA mutations was 5.41% (23/425) in breast and ovarian cancer patients of a Hakka population. The pathogenic, likely pathogenic, and benign mutations, and mutations of uncertain significance in this study mainly occurred in exon 14 of the BRCA1 gene, and exon 10 and exon 11 of the BRCA2 gene. CONCLUSIONS Understanding the spectrum and frequency of BRCA1 and BRCA2 mutations in a Hakka population will assist in the prevention and control of hereditary breast and ovarian cancers in this population.
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Affiliation(s)
- Heming Wu
- Center for Precision Medicine, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China, .,Guangdong Provincial Key Laboratory of Precision Medicine and Clinical Translational Research of Hakka Population, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China, .,Guangdong Provincial Engineering and Technology Research Center for Clinical Molecular Diagnostics and Antibody Therapeutics, Meizhou, China, .,Meizhou Municipal Engineering and Technology Research Center for Molecular Diagnostics of Major Genetic Disorders, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China,
| | - Qiuming Wang
- Guangdong Provincial Key Laboratory of Precision Medicine and Clinical Translational Research of Hakka Population, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China.,Center for Cancer Prevention and Treatment, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China
| | - Xuemin Guo
- Center for Precision Medicine, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China.,Guangdong Provincial Key Laboratory of Precision Medicine and Clinical Translational Research of Hakka Population, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China.,Guangdong Provincial Engineering and Technology Research Center for Clinical Molecular Diagnostics and Antibody Therapeutics, Meizhou, China.,Meizhou Municipal Engineering and Technology Research Center for Molecular Diagnostics of Major Genetic Disorders, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China
| | - Qinghua Liu
- Guangdong Provincial Key Laboratory of Precision Medicine and Clinical Translational Research of Hakka Population, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China.,Center for Pathological Diagnostics, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China
| | - Qunji Zhang
- Center for Precision Medicine, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China.,Guangdong Provincial Key Laboratory of Precision Medicine and Clinical Translational Research of Hakka Population, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China.,Guangdong Provincial Engineering and Technology Research Center for Clinical Molecular Diagnostics and Antibody Therapeutics, Meizhou, China.,Meizhou Municipal Engineering and Technology Research Center for Molecular Diagnostics of Major Genetic Disorders, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China
| | - Qingyan Huang
- Center for Precision Medicine, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China.,Guangdong Provincial Key Laboratory of Precision Medicine and Clinical Translational Research of Hakka Population, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China.,Guangdong Provincial Engineering and Technology Research Center for Clinical Molecular Diagnostics and Antibody Therapeutics, Meizhou, China.,Meizhou Municipal Engineering and Technology Research Center for Molecular Diagnostics of Major Genetic Disorders, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China
| | - Zhikang Yu
- Center for Precision Medicine, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China.,Guangdong Provincial Key Laboratory of Precision Medicine and Clinical Translational Research of Hakka Population, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China.,Guangdong Provincial Engineering and Technology Research Center for Clinical Molecular Diagnostics and Antibody Therapeutics, Meizhou, China.,Meizhou Municipal Engineering and Technology Research Center for Molecular Diagnostics of Major Genetic Disorders, Meizhou People's Hospital (Huangtang Hospital), Meizhou Academy of Medical Sciences, Meizhou Hospital Affiliated to Sun Yat-sen University, Meizhou, China
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Bagnolini G, Milano D, Manerba M, Schipani F, Ortega JA, Gioia D, Falchi F, Balboni A, Farabegoli F, De Franco F, Robertson J, Pellicciari R, Pallavicini I, Peri S, Minucci S, Girotto S, Di Stefano G, Roberti M, Cavalli A. Synthetic Lethality in Pancreatic Cancer: Discovery of a New RAD51-BRCA2 Small Molecule Disruptor That Inhibits Homologous Recombination and Synergizes with Olaparib. J Med Chem 2020; 63:2588-2619. [PMID: 32037829 PMCID: PMC7997579 DOI: 10.1021/acs.jmedchem.9b01526] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
![]()
Synthetic lethality
is an innovative framework for discovering
novel anticancer drug candidates. One example is the use of PARP inhibitors
(PARPi) in oncology patients with BRCA mutations.
Here, we exploit a new paradigm based on the possibility of triggering
synthetic lethality using only small organic molecules (dubbed “fully
small-molecule-induced synthetic lethality”). We exploited
this paradigm to target pancreatic cancer, one of the major unmet
needs in oncology. We discovered a dihydroquinolone pyrazoline-based
molecule (35d) that disrupts the RAD51-BRCA2 protein–protein
interaction, thus mimicking the effect of BRCA2 mutation. 35d inhibits the homologous recombination in a human pancreatic
adenocarcinoma cell line. In addition, it synergizes with olaparib
(a PARPi) to trigger synthetic lethality. This strategy aims to widen
the use of PARPi in BRCA-competent and olaparib-resistant
cancers, making fully small-molecule-induced synthetic lethality an
innovative approach toward unmet oncological needs.
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Affiliation(s)
- Greta Bagnolini
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy.,Department of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro 6, 40126 Bologna, Italy
| | - Domenico Milano
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy
| | - Marcella Manerba
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy
| | - Fabrizio Schipani
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy
| | - Jose Antonio Ortega
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy
| | - Dario Gioia
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy
| | - Federico Falchi
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy
| | - Andrea Balboni
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy.,Department of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro 6, 40126 Bologna, Italy
| | - Fulvia Farabegoli
- Department of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro 6, 40126 Bologna, Italy
| | - Francesca De Franco
- TES Pharma S.r.l., Via Palmiro Togliatti 22bis, I-06073 Corciano, Perugia, Italy
| | - Janet Robertson
- TES Pharma S.r.l., Via Palmiro Togliatti 22bis, I-06073 Corciano, Perugia, Italy
| | - Roberto Pellicciari
- TES Pharma S.r.l., Via Palmiro Togliatti 22bis, I-06073 Corciano, Perugia, Italy
| | - Isabella Pallavicini
- Department of Experimental Oncology at the IEO, European Institute of Oncology IRCCS, IFOM-IEO Campus, Via Adamello 16, 20100 Milan, Italy
| | - Sebastiano Peri
- Department of Experimental Oncology at the IEO, European Institute of Oncology IRCCS, IFOM-IEO Campus, Via Adamello 16, 20100 Milan, Italy
| | - Saverio Minucci
- Department of Biosciences, University of Milan, Via Celoria 26, 20100 Milan, Italy.,Department of Experimental Oncology at the IEO, European Institute of Oncology IRCCS, IFOM-IEO Campus, Via Adamello 16, 20100 Milan, Italy
| | - Stefania Girotto
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy
| | - Giuseppina Di Stefano
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Via S. Giacomo 14, 40126 Bologna, Italy
| | - Marinella Roberti
- Department of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro 6, 40126 Bologna, Italy
| | - Andrea Cavalli
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy.,Department of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro 6, 40126 Bologna, Italy
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46
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Sun Y, McCorvie TJ, Yates LA, Zhang X. Structural basis of homologous recombination. Cell Mol Life Sci 2020; 77:3-18. [PMID: 31748913 PMCID: PMC6957567 DOI: 10.1007/s00018-019-03365-1] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 10/10/2019] [Accepted: 10/31/2019] [Indexed: 12/12/2022]
Abstract
Homologous recombination (HR) is a pathway to faithfully repair DNA double-strand breaks (DSBs). At the core of this pathway is a DNA recombinase, which, as a nucleoprotein filament on ssDNA, pairs with homologous DNA as a template to repair the damaged site. In eukaryotes Rad51 is the recombinase capable of carrying out essential steps including strand invasion, homology search on the sister chromatid and strand exchange. Importantly, a tightly regulated process involving many protein factors has evolved to ensure proper localisation of this DNA repair machinery and its correct timing within the cell cycle. Dysregulation of any of the proteins involved can result in unchecked DNA damage, leading to uncontrolled cell division and cancer. Indeed, many are tumour suppressors and are key targets in the development of new cancer therapies. Over the past 40 years, our structural and mechanistic understanding of homologous recombination has steadily increased with notable recent advancements due to the advances in single particle cryo electron microscopy. These have resulted in higher resolution structural models of the signalling proteins ATM (ataxia telangiectasia mutated), and ATR (ataxia telangiectasia and Rad3-related protein), along with various structures of Rad51. However, structural information of the other major players involved, such as BRCA1 (breast cancer type 1 susceptibility protein) and BRCA2 (breast cancer type 2 susceptibility protein), has been limited to crystal structures of isolated domains and low-resolution electron microscopy reconstructions of the full-length proteins. Here we summarise the current structural understanding of homologous recombination, focusing on key proteins in recruitment and signalling events as well as the mediators for the Rad51 recombinase.
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Affiliation(s)
- Yueru Sun
- Section of Structural Biology, Department of Infectious Diseases, Imperial College, London, SW7 2AZ, UK
| | - Thomas J McCorvie
- Section of Structural Biology, Department of Infectious Diseases, Imperial College, London, SW7 2AZ, UK
| | - Luke A Yates
- Section of Structural Biology, Department of Infectious Diseases, Imperial College, London, SW7 2AZ, UK
| | - Xiaodong Zhang
- Section of Structural Biology, Department of Infectious Diseases, Imperial College, London, SW7 2AZ, UK.
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47
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Design, synthesis and interaction of BRC4 analogous peptides with RAD51(241–260). Amino Acids 2019; 52:361-369. [DOI: 10.1007/s00726-019-02813-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 12/12/2019] [Indexed: 02/05/2023]
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48
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Sima N, McLaughlin EJ, Hutchinson S, Glover L. Escaping the immune system by DNA repair and recombination in African trypanosomes. Open Biol 2019; 9:190182. [PMID: 31718509 PMCID: PMC6893398 DOI: 10.1098/rsob.190182] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
African trypanosomes escape the mammalian immune response by antigenic variation-the periodic exchange of one surface coat protein, in Trypanosoma brucei the variant surface glycoprotein (VSG), for an immunologically distinct one. VSG transcription is monoallelic, with only one VSG being expressed at a time from a specialized locus, known as an expression site. VSG switching is a predominantly recombination-driven process that allows VSG sequences to be recombined into the active expression site either replacing the currently active VSG or generating a 'new' VSG by segmental gene conversion. In this review, we describe what is known about the factors that influence this process, focusing specifically on DNA repair and recombination.
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Affiliation(s)
- Núria Sima
- Trypanosome Molecular Biology, Department of Parasites and Insect Vectors, Institut Pasteur, 25-28 Rue du Docteur Roux, 75015 Paris, France
| | - Emilia Jane McLaughlin
- Trypanosome Molecular Biology, Department of Parasites and Insect Vectors, Institut Pasteur, 25-28 Rue du Docteur Roux, 75015 Paris, France
| | - Sebastian Hutchinson
- Trypanosome Cell Biology and INSERM U1201, Department of Parasites and Insect Vectors, Institut Pasteur, 25-28 Rue du Docteur Roux, 75015 Paris, France
| | - Lucy Glover
- Trypanosome Molecular Biology, Department of Parasites and Insect Vectors, Institut Pasteur, 25-28 Rue du Docteur Roux, 75015 Paris, France
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49
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Park PH, Yamamoto TM, Li H, Alcivar AL, Xia B, Wang Y, Bernhardy AJ, Turner KM, Kossenkov AV, Watson ZL, Behbakht K, Casadei S, Swisher EM, Mischel PS, Johnson N, Bitler BG. Amplification of the Mutation-Carrying BRCA2 Allele Promotes RAD51 Loading and PARP Inhibitor Resistance in the Absence of Reversion Mutations. Mol Cancer Ther 2019; 19:602-613. [PMID: 31575654 DOI: 10.1158/1535-7163.mct-17-0256] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 08/04/2019] [Accepted: 09/26/2019] [Indexed: 12/27/2022]
Abstract
Patients harboring germline breast cancer susceptibility genes 1 and 2 (BRCA1/2) mutations are predisposed to developing breast, pancreatic, and ovarian cancers. BRCA2 plays a critical role in homologous recombination (HR) DNA repair and deleterious mutations in BRCA2 confer sensitivity to PARP inhibition. Recently, the PARP inhibitors olaparib and rucaparib were FDA approved for the treatment of metastatic breast cancer and patients with recurrent ovarian cancer with mutations in BRCA1/2. Despite their initial antitumor activity, the development of resistance limits the clinical utility of PARP inhibitor therapy. Multiple resistance mechanisms have been described, including reversion mutations that restore the reading frame of the BRCA2 gene. In this study, we generated olaparib- and rucaparib-resistant BRCA2-mutant Capan1 cell lines. We did not detect secondary reversion mutations in the olaparib- or rucaparib-resistant clones. Several of the resistant clones had gene duplication and amplification of the mutant BRCA2 allele, with a corresponding increase in expression of a truncated BRCA2 protein. In addition, HR-mediated DNA repair was rescued, as evidenced by the restoration of RAD51 foci formation. Using mass spectrometry, we identified Disruptor Of Telomeric silencing 1-Like (DOT1L), as an interacting partner of truncated BRCA2. RNAi-mediated knockdown of BRCA2 or DOT1L was sufficient to resensitize cells to olaparib. The results demonstrate that independent of a BRCA2 reversion, mutation amplification of a mutant-carrying BRCA2 contributes to PARP inhibitor resistance.
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Affiliation(s)
- Pyoung Hwa Park
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania
| | - Tomomi M Yamamoto
- Division of Reproductive Sciences, The University of Colorado, Aurora, Colorado
| | - Hua Li
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania
| | - Allen L Alcivar
- Department of Radiation Oncology, The Cancer Institute of New Jersey, Rutgers University, New Brunswick, New Jersey
| | - Bing Xia
- Department of Radiation Oncology, The Cancer Institute of New Jersey, Rutgers University, New Brunswick, New Jersey
| | - Yifan Wang
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Andrea J Bernhardy
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Kristen M Turner
- Moores Cancer Center, University of California at San Diego, La Jolla, California
| | - Andrew V Kossenkov
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania
| | - Zachary L Watson
- Division of Reproductive Sciences, The University of Colorado, Aurora, Colorado
| | - Kian Behbakht
- Division of Gynecologic Oncology, The University of Colorado, Aurora, Colorado
| | - Silvia Casadei
- Department of Ob/Gyn, University of Washington, Seattle, Washington
| | | | - Paul S Mischel
- Moores Cancer Center, University of California at San Diego, La Jolla, California
| | - Neil Johnson
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Benjamin G Bitler
- Division of Reproductive Sciences, The University of Colorado, Aurora, Colorado.
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50
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López-Camarillo C, Rincón DG, Ruiz-García E, Astudillo-de la Vega H, Marchat LA. DNA Repair Proteins as Therapeutic Targets in Ovarian Cancer. Curr Protein Pept Sci 2019; 20:316-323. [PMID: 30215333 DOI: 10.2174/1389203719666180914091537] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 08/15/2018] [Accepted: 09/12/2018] [Indexed: 12/27/2022]
Abstract
Epithelial ovarian cancer is a serious public health problem worldwide with the highest mortality rate of all gynecologic cancers. The current standard-of-care for the treatment of ovarian cancer is based on chemotherapy based on adjuvant cisplatin/carboplatin and taxane regimens that represent the first-line agents for patients with advanced disease. The DNA repair activity of cancer cells determines the efficacy of anticancer drugs. These features make DNA repair mechanisms a promising target for novel cancer treatments. In this context a better understanding of the DNA damage response caused by antitumor agents has provided the basis for the use of DNA repair inhibitors to improve the therapeutic use of DNA-damaging drugs. In this review, we will discuss the functions of DNA repair proteins and the advances in targeting DNA repair pathways with special emphasis in the inhibition of HRR and BER in ovarian cancer. We focused in the actual efforts in the development and clinical use of poly (ADPribose) polymerase (PARP) inhibitors for the intervention of BRCA1/BRCA2-deficient ovarian tumors. The clinical development of PARP inhibitors in ovarian cancer patients with germline BRCA1/2 mutations and sporadic high-grade serous ovarian cancer is ongoing. Some phase II and phase III trials have been completed with promising results for ovarian cancer patients.
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Affiliation(s)
- César López-Camarillo
- Posgrado en Ciencias Genomicas, Universidad Autonoma de la Ciudad de Mexico, México City, Mexico
| | - Dolores G Rincón
- Laboratorio de Medicina Translacional. Instituto Nacional de Cancerologia, Ciudad de Mexico, Mexico
| | - Erika Ruiz-García
- Laboratorio de Medicina Translacional. Instituto Nacional de Cancerologia, Ciudad de Mexico, Mexico
| | - Horacio Astudillo-de la Vega
- Laboratorio de Investigacion Translacional en Cancer y Terapia Celular, Hospital de Oncologia Centro Medico Nacional Siglo XXI, Mexico
| | - Laurence A Marchat
- Programa en Biomedicina Molecular y Red de Biotecnologia. Instituto Politecnico Nacional. Ciudad de Mexico, Mexico
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