1
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Bader AS, Bushell M. iMUT-seq: high-resolution DSB-induced mutation profiling reveals prevalent homologous-recombination dependent mutagenesis. Nat Commun 2023; 14:8419. [PMID: 38110444 PMCID: PMC10728174 DOI: 10.1038/s41467-023-44167-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 12/04/2023] [Indexed: 12/20/2023] Open
Abstract
DNA double-strand breaks (DSBs) are the most mutagenic form of DNA damage, and play a significant role in cancer biology, neurodegeneration and aging. However, studying DSB-induced mutagenesis is limited by our current approaches. Here, we describe iMUT-seq, a technique that profiles DSB-induced mutations at high-sensitivity and single-nucleotide resolution around endogenous DSBs. By depleting or inhibiting 20 DSB-repair factors we define their mutational signatures in detail, revealing insights into the mechanisms of DSB-induced mutagenesis. Notably, we find that homologous-recombination (HR) is more mutagenic than previously thought, inducing prevalent base substitutions and mononucleotide deletions at distance from the break due to DNA-polymerase errors. Simultaneously, HR reduces translocations, suggesting a primary role of HR is specifically the prevention of genomic rearrangements. The results presented here offer fundamental insights into DSB-induced mutagenesis and have significant implications for our understanding of cancer biology and the development of DDR-targeting chemotherapeutics.
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Affiliation(s)
- Aldo S Bader
- Cancer Research UK Beatson Institute, Glasgow, G61 1BD, UK.
- Cancer Research UK/CI, University of Cambridge, Li Ka Shing Centre, Cambridge, CB2 0RE, UK.
- The Gurdon Institute, University of Cambridge, Biochemistry, Cambridge, UK.
| | - Martin Bushell
- Cancer Research UK Beatson Institute, Glasgow, G61 1BD, UK.
- Institute of Cancer Sciences, University of Glasgow, Glasgow, G61 1QH, UK.
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2
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Traband EL, Hammerlund SR, Shameem M, Narayan A, Ramana S, Tella A, Sobeck A, Shima N. Mitotic DNA Synthesis in Untransformed Human Cells Preserves Common Fragile Site Stability via a FANCD2-Driven Mechanism That Requires HELQ. J Mol Biol 2023; 435:168294. [PMID: 37777152 PMCID: PMC10839910 DOI: 10.1016/j.jmb.2023.168294] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 09/14/2023] [Accepted: 09/25/2023] [Indexed: 10/02/2023]
Abstract
Faithful genome duplication is a challenging task for dividing mammalian cells, particularly under replication stress where timely resolution of late replication intermediates (LRIs) becomes crucial prior to cell division. In human cancer cells, mitotic DNA repair synthesis (MiDAS) is described as a final mechanism for the resolution of LRIs to avoid lethal chromosome mis-segregation. RAD52-driven MiDAS achieves this mission in part by generating gaps/breaks on metaphase chromosomes, which preferentially occur at common fragile sites (CFS). We previously demonstrated that a MiDAS mechanism also exists in untransformed and primary human cells, which is RAD52 independent but requires FANCD2. However, the properties of this form of MiDAS are not well understood. Here, we report that FANCD2-driven MiDAS in untransformed human cells: 1) requires a prerequisite step of FANCD2 mono-ubiquitination by a subset of Fanconi anemia (FA) proteins, 2) primarily acts to preserve CFS stability but not to prevent chromosome mis-segregation, and 3) depends on HELQ, which potentially functions at an early step. Hence, FANCD2-driven MiDAS in untransformed cells is built to protect CFS stability, whereas RAD52-driven MiDAS in cancer cells is likely adapted to prevent chromosome mis-segregation at the cost of CFS expression. Notably, we also identified a novel form of MiDAS, which surfaces to function when FANCD2 is absent in untransformed cells. Our findings substantiate the complex nature of MiDAS and a link between its deficiencies and the pathogenesis of FA, a human genetic disease.
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Affiliation(s)
- Emma L Traband
- Department of Genetics, Cell Biology and Development, Medical School, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA; Department of Biochemistry, Molecular Biology, and Biophysics, College of Biological Sciences, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA
| | - Sarah R Hammerlund
- Department of Genetics, Cell Biology and Development, Medical School, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA; Department of Biochemistry, Molecular Biology, and Biophysics, College of Biological Sciences, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA
| | - Mohammad Shameem
- Department of Biochemistry, Molecular Biology, and Biophysics, College of Biological Sciences, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA
| | - Ananya Narayan
- Department of Genetics, Cell Biology and Development, Medical School, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA
| | - Sanjiv Ramana
- Department of Genetics, Cell Biology and Development, Medical School, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA
| | - Anika Tella
- Department of Genetics, Cell Biology and Development, Medical School, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA
| | - Alexandra Sobeck
- Department of Biochemistry, Molecular Biology, and Biophysics, College of Biological Sciences, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, Minneapolis, MN 55455, USA
| | - Naoko Shima
- Department of Genetics, Cell Biology and Development, Medical School, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, Minneapolis, MN 55455, USA.
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3
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Bhat D, Malacaria E, Biagi L, Razzaghi M, Honda M, Hobbs K, Hengel S, Pichierri P, Spies M, Spies M. Therapeutic disruption of RAD52-ssDNA complexation via novel drug-like inhibitors. NAR Cancer 2023; 5:zcad018. [PMID: 37139244 PMCID: PMC10150327 DOI: 10.1093/narcan/zcad018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/09/2023] [Accepted: 04/14/2023] [Indexed: 05/05/2023] Open
Abstract
RAD52 protein is a coveted target for anticancer drug discovery. Similar to poly-ADP-ribose polymerase (PARP) inhibitors, pharmacological inhibition of RAD52 is synthetically lethal with defects in genome caretakers BRCA1 and BRCA2 (∼25% of breast and ovarian cancers). Emerging structure activity relationships for RAD52 are complex, making it challenging to transform previously identified disruptors of the RAD52-ssDNA interaction into drug-like leads using traditional medicinal chemistry approaches. Using pharmacophoric informatics on the RAD52 complexation by epigallocatechin (EGC), and the Enamine in silico REAL database, we identified six distinct chemical scaffolds that occupy the same physical space on RAD52 as EGC. All six were RAD52 inhibitors (IC50 ∼23-1200 μM) with two of the compounds (Z56 and Z99) selectively killing BRCA-mutant cells and inhibiting cellular activities of RAD52 at micromolar inhibitor concentrations. While Z56 had no effect on the ssDNA-binding protein RPA and was toxic to BRCA-mutant cells only, Z99 inhibited both proteins and displayed toxicity towards BRCA-complemented cells. Optimization of the Z99 scaffold resulted in a set of more powerful and selective inhibitors (IC50 ∼1.3-8 μM), which were only toxic to BRCA-mutant cells. RAD52 complexation by Z56, Z99 and its more specific derivatives provide a roadmap for next generation of cancer therapeutics.
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Affiliation(s)
- Divya S Bhat
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
| | - Eva Malacaria
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Ludovica Di Biagi
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Mortezaali Razzaghi
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
| | - Masayoshi Honda
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
| | - Kathryn F Hobbs
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
- Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, The University of Iowa, Iowa City, IA 52242, USA
| | - Sarah R Hengel
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
| | - Pietro Pichierri
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - M Ashley Spies
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
- Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, The University of Iowa, Iowa City, IA 52242, USA
- Naturis Informatika LLC, 401 Mullin Ave., Iowa City, IA 52246, USA
| | - Maria Spies
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
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4
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Sachsenweger J, Jansche R, Merk T, Heitmeir B, Deniz M, Faust U, Roggia C, Tzschach A, Schroeder C, Riess A, Pospiech H, Peltoketo H, Pylkäs K, Winqvist R, Wiesmüller L. ABRAXAS1 orchestrates BRCA1 activities to counter genome destabilizing repair pathways-lessons from breast cancer patients. Cell Death Dis 2023; 14:328. [PMID: 37198153 DOI: 10.1038/s41419-023-05845-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 04/27/2023] [Accepted: 05/02/2023] [Indexed: 05/19/2023]
Abstract
It has been well-established that mutations in BRCA1 and BRCA2, compromising functions in DNA double-strand break repair (DSBR), confer hereditary breast and ovarian cancer risk. Importantly, mutations in these genes explain only a minor fraction of the hereditary risk and of the subset of DSBR deficient tumors. Our screening efforts identified two truncating germline mutations in the gene encoding the BRCA1 complex partner ABRAXAS1 in German early-onset breast cancer patients. To unravel the molecular mechanisms triggering carcinogenesis in these carriers of heterozygous mutations, we examined DSBR functions in patient-derived lymphoblastoid cells (LCLs) and in genetically manipulated mammary epithelial cells. By use of these strategies we were able to demonstrate that these truncating ABRAXAS1 mutations exerted dominant effects on BRCA1 functions. Interestingly, we did not observe haploinsufficiency regarding homologous recombination (HR) proficiency (reporter assay, RAD51-foci, PARP-inhibitor sensitivity) in mutation carriers. However, the balance was shifted to use of mutagenic DSBR-pathways. The dominant effect of truncated ABRAXAS1 devoid of the C-terminal BRCA1 binding site can be explained by retention of the N-terminal interaction sites for other BRCA1-A complex partners like RAP80. In this case BRCA1 was channeled from the BRCA1-A to the BRCA1-C complex, which induced single-strand annealing (SSA). Further truncation, additionally deleting the coiled-coil region of ABRAXAS1, unleashed excessive DNA damage responses (DDRs) de-repressing multiple DSBR-pathways including SSA and non-homologous end-joining (NHEJ). Our data reveal de-repression of low-fidelity repair activities as a common feature of cells from patients with heterozygous mutations in genes encoding BRCA1 and its complex partners.
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Affiliation(s)
- Juliane Sachsenweger
- Department of Obstetrics and Gynecology, Ulm University, Ulm, Germany
- Laboratory of Cancer Genetics and Tumor Biology, Translational Medicine Research Unit, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Rebecca Jansche
- Department of Obstetrics and Gynecology, Ulm University, Ulm, Germany
| | - Tatjana Merk
- Department of Obstetrics and Gynecology, Ulm University, Ulm, Germany
| | - Benedikt Heitmeir
- Department of Obstetrics and Gynecology, Ulm University, Ulm, Germany
| | - Miriam Deniz
- Department of Obstetrics and Gynecology, Ulm University, Ulm, Germany
| | - Ulrike Faust
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Cristiana Roggia
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Andreas Tzschach
- Institute of Human Genetics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Christopher Schroeder
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Angelika Riess
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Helmut Pospiech
- Leibniz Institute on Aging - Fritz Lipmann Institute, Jena, Germany
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Hellevi Peltoketo
- Laboratory of Cancer Genetics and Tumor Biology, Translational Medicine Research Unit, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Katri Pylkäs
- Laboratory of Cancer Genetics and Tumor Biology, Translational Medicine Research Unit, Biocenter Oulu, University of Oulu, Oulu, Finland
- Laboratory of Cancer Genetics and Tumor Biology, Northern Finland Laboratory Centre, Oulu, Finland
| | - Robert Winqvist
- Laboratory of Cancer Genetics and Tumor Biology, Translational Medicine Research Unit, Biocenter Oulu, University of Oulu, Oulu, Finland
- Laboratory of Cancer Genetics and Tumor Biology, Northern Finland Laboratory Centre, Oulu, Finland
| | - Lisa Wiesmüller
- Department of Obstetrics and Gynecology, Ulm University, Ulm, Germany.
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5
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Balboni B, Rinaldi F, Previtali V, Ciamarone A, Girotto S, Cavalli A. Novel Insights into RAD52’s Structure, Function, and Druggability for Synthetic Lethality and Innovative Anticancer Therapies. Cancers (Basel) 2023; 15:cancers15061817. [PMID: 36980703 PMCID: PMC10046612 DOI: 10.3390/cancers15061817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/08/2023] [Accepted: 03/14/2023] [Indexed: 03/19/2023] Open
Abstract
In recent years, the RAD52 protein has been highlighted as a mediator of many DNA repair mechanisms. While RAD52 was initially considered to be a non-essential auxiliary factor, its inhibition has more recently been demonstrated to be synthetically lethal in cancer cells bearing mutations and inactivation of specific intracellular pathways, such as homologous recombination. RAD52 is now recognized as a novel and critical pharmacological target. In this review, we comprehensively describe the available structural and functional information on RAD52. The review highlights the pathways in which RAD52 is involved and the approaches to RAD52 inhibition. We discuss the multifaceted role of this protein, which has a complex, dynamic, and functional 3D superstructural arrangement. This complexity reinforces the need to further investigate and characterize RAD52 to solve a challenging mechanistic puzzle and pave the way for a robust drug discovery campaign.
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Affiliation(s)
- Beatrice 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
| | - Francesco Rinaldi
- 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
| | - Viola Previtali
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genoa, Italy
| | - Andrea Ciamarone
- 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
| | - Stefania Girotto
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genoa, Italy
- Structural Biophysics and Translational Pharmacology Facility, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genoa, Italy
- Correspondence: (S.G.); (A.C.); Tel.: +39-010-2896-983 (S.G.); +39-010-2897-403 (A.C.)
| | - 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
- Correspondence: (S.G.); (A.C.); Tel.: +39-010-2896-983 (S.G.); +39-010-2897-403 (A.C.)
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6
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Wang C, Chan DW, Hendrickson EA. Kinome-wide screening uncovers a role for Bromodomain Protein 3 in DNA double-stranded break repair. DNA Repair (Amst) 2023; 122:103445. [PMID: 36608404 PMCID: PMC10353298 DOI: 10.1016/j.dnarep.2022.103445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 12/17/2022] [Accepted: 12/22/2022] [Indexed: 12/25/2022]
Abstract
Double-stranded breaks (DSBs) are toxic DNA damage and a serious threat to genomic integrity. Thus, all living organisms have evolved multiple mechanisms of DNA DSB repair, the two principal ones being classical-non homologous end joining (C-NHEJ), and homology dependent recombination (HDR). In mammals, C-NHEJ is the predominate DSB repair pathway, but how a cell chooses to repair a particular DSB by a certain pathway is still not mechanistically clear. To uncover novel regulators of DSB repair pathway choice, we performed a kinome-wide screen in a human cell line engineered to express a dominant-negative C-NHEJ factor. The intellectual basis for such a screen was our hypothesis that a C-NHEJ-crippled cell line might need to upregulate other DSB repair pathways, including HDR, in order to survive. This screen identified Bromodomain-containing Protein 3 (BRD3) as a protein whose expression was almost completely ablated specifically in a C-NHEJ-defective cell line. Subsequent experimentation demonstrated that BRD3 is a negative regulator of HDR as BRD3-null cell lines proved to be hyper-recombinogenic for gene conversion, sister chromatid exchanges and gene targeting. Mechanistically, BRD3 appears to be working at the level of Radiation Sensitive 51 (RAD51) recruitment. Overall, our results demonstrate that BRD3 is a novel regulator of human DSB repair pathway choice.
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Affiliation(s)
- Chen Wang
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Medical School, Minneapolis, MN, 55455, USA
| | - Doug W Chan
- Department of Systems Biology, University of Texas, MD Anderson Cancer Center, Houston, TX, 77030
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Medical School, Minneapolis, MN, 55455, USA.
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7
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Bhat DS, Spies MA, Spies M. A moving target for drug discovery: Structure activity relationship and many genome (de)stabilizing functions of the RAD52 protein. DNA Repair (Amst) 2022; 120:103421. [PMID: 36327799 PMCID: PMC9888176 DOI: 10.1016/j.dnarep.2022.103421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 10/18/2022] [Accepted: 10/24/2022] [Indexed: 02/02/2023]
Abstract
BRCA-ness phenotype, a signature of many breast and ovarian cancers, manifests as deficiency in homologous recombination, and as defects in protection and repair of damaged DNA replication forks. A dependence of such cancers on DNA repair factors less important for survival of BRCA-proficient cells, offers opportunities for development of novel chemotherapeutic interventions. The first drugs targeting BRCA-deficient cancers, poly-ADP-ribose polymerase (PARP) inhibitors have been approved for the treatment of advanced, chemotherapy resistant cancers in patients with BRCA1/2 germline mutations. Nine additional proteins that can be targeted to selectively kill BRCA-deficient cancer cells have been identified. Among them, a DNA repair protein RAD52 is an especially attractive target due to general tolerance of the RAD52 loss of function, and protective role of an inactivating mutation. Yet, the effective pharmacological inhibitors of RAD52 have not been forthcoming. In this review, we discuss advances in the state of our knowledge of the RAD52 structure, activities and cellular functions, with a specific focus on the features that make RAD52 an attractive, but difficult drug target.
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Affiliation(s)
- Divya S Bhat
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
| | - M Ashley Spies
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA; Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Maria Spies
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA.
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8
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Rossi MJ, DiDomenico SF, Patel M, Mazin AV. RAD52: Paradigm of Synthetic Lethality and New Developments. Front Genet 2021; 12:780293. [PMID: 34887904 PMCID: PMC8650160 DOI: 10.3389/fgene.2021.780293] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 11/05/2021] [Indexed: 12/31/2022] Open
Abstract
DNA double-strand breaks and inter-strand cross-links are the most harmful types of DNA damage that cause genomic instability that lead to cancer development. The highest fidelity pathway for repairing damaged double-stranded DNA is termed Homologous recombination (HR). Rad52 is one of the key HR proteins in eukaryotes. Although it is critical for most DNA repair and recombination events in yeast, knockouts of mammalian RAD52 lack any discernable phenotypes. As a consequence, mammalian RAD52 has been long overlooked. That is changing now, as recent work has shown RAD52 to be critical for backup DNA repair pathways in HR-deficient cancer cells. Novel findings have shed light on RAD52's biochemical activities. RAD52 promotes DNA pairing (D-loop formation), single-strand DNA and DNA:RNA annealing, and inverse strand exchange. These activities contribute to its multiple roles in DNA damage repair including HR, single-strand annealing, break-induced replication, and RNA-mediated repair of DNA. The contributions of RAD52 that are essential to the viability of HR-deficient cancer cells are currently under investigation. These new findings make RAD52 an attractive target for the development of anti-cancer therapies against BRCA-deficient cancers.
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9
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Al-Zain AM, Symington LS. The dark side of homology-directed repair. DNA Repair (Amst) 2021; 106:103181. [PMID: 34311272 DOI: 10.1016/j.dnarep.2021.103181] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 07/16/2021] [Accepted: 07/16/2021] [Indexed: 10/20/2022]
Abstract
DNA double strand breaks (DSB) are cytotoxic lesions that can lead to genome rearrangements and genomic instability, which are hallmarks of cancer. The two main DSB repair pathways are non-homologous end joining and homologous recombination (HR). While HR is generally highly accurate, it has the potential for rearrangements that occur directly or through intermediates generated during the repair process. Whole genome sequencing of cancers has revealed numerous types of structural rearrangement signatures that are often indicative of repair mediated by sequence homology. However, it can be challenging to delineate repair mechanisms from sequence analysis of rearrangement end products from cancer genomes, or even model systems, because the same rearrangements can be generated by different pathways. Here, we review homology-directed repair pathways and their consequences. Exploring those pathways can lead to a greater understanding of rearrangements that occur in cancer cells.
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Affiliation(s)
- Amr M Al-Zain
- Program in Biological Sciences, Columbia University, New York, NY, 10027, United States; Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, United States
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, United States; Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY, 10032, United States.
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10
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Kavli B, Iveland TS, Buchinger E, Hagen L, Liabakk NB, Aas PA, Obermann TS, Aachmann FL, Slupphaug G. RPA2 winged-helix domain facilitates UNG-mediated removal of uracil from ssDNA; implications for repair of mutagenic uracil at the replication fork. Nucleic Acids Res 2021; 49:3948-3966. [PMID: 33784377 PMCID: PMC8053108 DOI: 10.1093/nar/gkab195] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 03/04/2021] [Accepted: 03/10/2021] [Indexed: 01/14/2023] Open
Abstract
Uracil occurs at replication forks via misincorporation of deoxyuridine monophosphate (dUMP) or via deamination of existing cytosines, which occurs 2-3 orders of magnitude faster in ssDNA than in dsDNA and is 100% miscoding. Tethering of UNG2 to proliferating cell nuclear antigen (PCNA) allows rapid post-replicative removal of misincorporated uracil, but potential 'pre-replicative' removal of deaminated cytosines in ssDNA has been questioned since this could mediate mutagenic translesion synthesis and induction of double-strand breaks. Here, we demonstrate that uracil-DNA glycosylase (UNG), but not SMUG1 efficiently excises uracil from replication protein A (RPA)-coated ssDNA and that this depends on functional interaction between the flexible winged-helix (WH) domain of RPA2 and the N-terminal RPA-binding helix in UNG. This functional interaction is promoted by mono-ubiquitination and diminished by cell-cycle regulated phosphorylations on UNG. Six other human proteins bind the RPA2-WH domain, all of which are involved in DNA repair and replication fork remodelling. Based on this and the recent discovery of the AP site crosslinking protein HMCES, we propose an integrated model in which templated repair of uracil and potentially other mutagenic base lesions in ssDNA at the replication fork, is orchestrated by RPA. The UNG:RPA2-WH interaction may also play a role in adaptive immunity by promoting efficient excision of AID-induced uracils in transcribed immunoglobulin loci.
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Affiliation(s)
- Bodil Kavli
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.,Clinic of Laboratory Medicine, St. Olavs Hospital, Trondheim University Hospital, NO-7006 Trondheim, Norway
| | - Tobias S Iveland
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.,Cancer Clinic, St. Olavs Hospital, Trondheim University Hospital, NO-7006 Trondheim, Norway
| | - Edith Buchinger
- NOBIPOL, Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, N-7034 Trondheim, Norway
| | - Lars Hagen
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.,Clinic of Laboratory Medicine, St. Olavs Hospital, Trondheim University Hospital, NO-7006 Trondheim, Norway.,PROMEC Proteomics and Modomics Experimental Core at NTNU and the Central Norway Regional Health Authority, NO-7491 Trondheim, Norway
| | - Nina B Liabakk
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.,Clinic of Laboratory Medicine, St. Olavs Hospital, Trondheim University Hospital, NO-7006 Trondheim, Norway
| | - Per A Aas
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.,Clinic of Laboratory Medicine, St. Olavs Hospital, Trondheim University Hospital, NO-7006 Trondheim, Norway
| | - Tobias S Obermann
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.,Clinic of Laboratory Medicine, St. Olavs Hospital, Trondheim University Hospital, NO-7006 Trondheim, Norway
| | - Finn L Aachmann
- NOBIPOL, Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, N-7034 Trondheim, Norway
| | - Geir Slupphaug
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.,Clinic of Laboratory Medicine, St. Olavs Hospital, Trondheim University Hospital, NO-7006 Trondheim, Norway.,PROMEC Proteomics and Modomics Experimental Core at NTNU and the Central Norway Regional Health Authority, NO-7491 Trondheim, Norway
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11
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Nelson CB, Alturki TM, Luxton JJ, Taylor LE, Maranon DG, Muraki K, Murnane JP, Bailey SM. Telomeric Double Strand Breaks in G1 Human Cells Facilitate Formation of 5' C-Rich Overhangs and Recruitment of TERRA. Front Genet 2021; 12:644803. [PMID: 33841503 PMCID: PMC8027502 DOI: 10.3389/fgene.2021.644803] [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: 12/21/2020] [Accepted: 02/08/2021] [Indexed: 12/12/2022] Open
Abstract
Telomeres, repetitive nucleoprotein complexes that protect chromosomal termini and prevent them from activating inappropriate DNA damage responses (DDRs), shorten with cell division and thus with aging. Here, we characterized the human cellular response to targeted telomeric double-strand breaks (DSBs) in telomerase-positive and telomerase-independent alternative lengthening of telomere (ALT) cells, specifically in G1 phase. Telomeric DSBs in human G1 cells elicited early signatures of a DDR; however, localization of 53BP1, an important regulator of resection at broken ends, was not observed at telomeric break sites. Consistent with this finding and previously reported repression of classical non-homologous end-joining (c-NHEJ) at telomeres, evidence for c-NHEJ was also lacking. Likewise, no evidence of homologous recombination (HR)-dependent repair of telomeric DSBs in G1 was observed. Rather, and supportive of rapid truncation events, telomeric DSBs in G1 human cells facilitated formation of extensive tracks of resected 5′ C-rich telomeric single-stranded (ss)DNA, a previously proposed marker of the recombination-dependent ALT pathway. Indeed, induction of telomeric DSBs in human ALT cells resulted in significant increases in 5′ C-rich (ss)telomeric DNA in G1, which rather than RPA, was bound by the complementary telomeric RNA, TERRA, presumably to protect these exposed ends so that they persist into S/G2 for telomerase-mediated or HR-dependent elongation, while also circumventing conventional repair pathways. Results demonstrate the remarkable adaptability of telomeres, and thus they have important implications for persistent telomeric DNA damage in normal human G1/G0 cells (e.g., lymphocytes), as well as for therapeutically relevant targets to improve treatment of ALT-positive tumors.
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Affiliation(s)
- Christopher B Nelson
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States.,Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO, United States
| | - Taghreed M Alturki
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States.,Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO, United States
| | - Jared J Luxton
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States.,Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO, United States
| | - Lynn E Taylor
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States
| | - David G Maranon
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States
| | - Keiko Muraki
- Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA, United States
| | - John P Murnane
- Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA, United States
| | - Susan M Bailey
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States.,Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO, United States
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12
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Wang J, Oh YT, Li Z, Dou J, Tang S, Wang X, Wang H, Takeda S, Wang Y. RAD52 Adjusts Repair of Single-Strand Breaks via Reducing DNA-Damage-Promoted XRCC1/LIG3α Co-localization. Cell Rep 2021; 34:108625. [PMID: 33440161 PMCID: PMC7872142 DOI: 10.1016/j.celrep.2020.108625] [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: 07/06/2020] [Revised: 10/20/2020] [Accepted: 12/17/2020] [Indexed: 11/07/2022] Open
Abstract
Radiation sensitive 52 (RAD52) is an important factor for double-strand break repair (DSBR). However, deficiency in vertebrate/mammalian Rad52 has no apparent phenotype. The underlying mechanism remains elusive. Here, we report that RAD52 deficiency increased cell survival after camptothecin (CPT) treatment. CPT generates single-strand breaks (SSBs) that further convert to double-strand breaks (DSBs) if they are not repaired. RAD52 inhibits SSB repair (SSBR) through strong single-strand DNA (ssDNA) and/or poly(ADP-ribose) (PAR) binding affinity to reduce DNA-damage-promoted X-Ray Repair Cross Complementing 1 (XRCC1)/ligase IIIα (LIG3α) co-localization. The inhibitory effects of RAD52 on SSBR neutralize the role of RAD52 in DSBR, suggesting that RAD52 may maintain a balance between cell survival and genomic integrity. Furthermore, we demonstrate that blocking RAD52 oligomerization that disrupts RAD52’s DSBR, while retaining its ssDNA binding capacity that is required for RAD52’s inhibitory effects on SSBR, sensitizes cells to different DNA-damaging agents. This discovery provides guidance for developing efficient RAD52 inhibitors in cancer therapy. Wang et al. show that vertebrate/mammalian RAD52 promotes CPT-induced cell death via inhibition of PARP-mediated SSBR, which involves RAD52’s strong ssDNA/PAR binding affinity that reduces DNA-damage-promoted XRCC1-LIG3a interaction. Blocking of RAD52 oligomerization, while retaining the ssDNA binding capacity of RAD52, efficiently sensitizes cells to different DNA-damaging agents.
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Affiliation(s)
- Jian Wang
- Department of Radiation Oncology, Emory University School of Medicine and the Winship Cancer Institute of Emory University, Atlanta, GA 30322, USA
| | - You-Take Oh
- Department of Radiation Oncology, Emory University School of Medicine and the Winship Cancer Institute of Emory University, Atlanta, GA 30322, USA
| | - Zhentian Li
- Department of Radiation Oncology, Emory University School of Medicine and the Winship Cancer Institute of Emory University, Atlanta, GA 30322, USA
| | - Juan Dou
- Department of Radiation Oncology, Emory University School of Medicine and the Winship Cancer Institute of Emory University, Atlanta, GA 30322, USA
| | - Siyuan Tang
- Department of Radiation Oncology, Emory University School of Medicine and the Winship Cancer Institute of Emory University, Atlanta, GA 30322, USA
| | - Xiang Wang
- Department of Radiation Oncology, Emory University School of Medicine and the Winship Cancer Institute of Emory University, Atlanta, GA 30322, USA
| | - Hongyan Wang
- Department of Radiation Oncology, Emory University School of Medicine and the Winship Cancer Institute of Emory University, Atlanta, GA 30322, USA
| | - Shunichi Takeda
- CREST Research Project, Radiation Genetics, Faculty of Medicine, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan.
| | - Ya Wang
- Department of Radiation Oncology, Emory University School of Medicine and the Winship Cancer Institute of Emory University, Atlanta, GA 30322, USA.
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13
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Vpu modulates DNA repair to suppress innate sensing and hyper-integration of HIV-1. Nat Microbiol 2020; 5:1247-1261. [PMID: 32690953 DOI: 10.1038/s41564-020-0753-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 06/11/2020] [Indexed: 12/19/2022]
Abstract
To avoid innate sensing and immune control, human immunodeficiency virus type 1 (HIV-1) has to prevent the accumulation of viral complementary DNA species. Here, we show that the late HIV-1 accessory protein Vpu hijacks DNA repair mechanisms to promote degradation of nuclear viral cDNA in cells that are already productively infected. Vpu achieves this by interacting with RanBP2-RanGAP1*SUMO1-Ubc9 SUMO E3-ligase complexes at the nuclear pore to reprogramme promyelocytic leukaemia protein nuclear bodies and reduce SUMOylation of Bloom syndrome protein, unleashing end degradation of viral cDNA. Concomitantly, Vpu inhibits RAD52-mediated homologous repair of viral cDNA, preventing the generation of dead-end circular forms of single copies of the long terminal repeat and permitting sustained nucleolytic attack. Our results identify Vpu as a key modulator of the DNA repair machinery. We show that Bloom syndrome protein eliminates nuclear HIV-1 cDNA and thereby suppresses immune sensing and proviral hyper-integration. Therapeutic targeting of DNA repair may facilitate the induction of antiviral immunity and suppress proviral integration replenishing latent HIV reservoirs.
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14
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Current Understanding of RAD52 Functions: Fundamental and Therapeutic Insights. Cancers (Basel) 2020; 12:cancers12030705. [PMID: 32192055 PMCID: PMC7140074 DOI: 10.3390/cancers12030705] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 03/13/2020] [Indexed: 02/07/2023] Open
Abstract
In this Special Issue, we would like to focus on the various functions of the RAD52 helicase-like protein and the current implications of such findings for cancer treatment. Over the last few years, various laboratories have discovered particular activities of mammalian RAD52—both in S and M phase—that are distinct from the auxiliary role of yeast RAD52 in homologous recombination. At DNA double-strand breaks, RAD52 was demonstrated to spur alternative pathways to compensate for the loss of homologous recombination functions. At collapsed replication forks, RAD52 activates break-induced replication. In the M phase, RAD52 promotes the finalization of DNA replication. Its compensatory role in the resolution of DNA double-strand breaks has put RAD52 in the focus of synthetic lethal strategies, which is particularly relevant for cancer treatment.
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15
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Ho V, Chung L, Singh A, Lea V, Abubakar A, Lim SH, Chua W, Ng W, Lee M, Roberts TL, de Souza P, Lee CS. Aberrant Expression of RAD52, Its Prognostic Impact in Rectal Cancer and Association with Poor Survival of Patients. Int J Mol Sci 2020; 21:ijms21051768. [PMID: 32143539 PMCID: PMC7084626 DOI: 10.3390/ijms21051768] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 02/29/2020] [Accepted: 03/01/2020] [Indexed: 12/18/2022] Open
Abstract
The DNA damage response enables cells to survive and maintain genome integrity. RAD52 is a DNA-binding protein involved in the homologous recombination in DNA repair, and is important for the maintenance of tumour genome integrity. We investigated possible correlations between RAD52 expression and cancer survival and response to preoperative radiotherapy. RAD52 expression was examined in tumour samples from 179 patients who underwent surgery for rectal cancer, including a sub-cohort of 40 patients who were treated with neoadjuvant therapy. A high score for RAD52 expression in the tumour centre was significantly associated with worse disease-free survival (DFS; p = 0.045). In contrast, reduced RAD52 expression in tumour centre samples from patients treated with neoadjuvant therapy (n = 40) significantly correlated with poor DFS (p = 0.025) and overall survival (OS; p = 0.048). Our results suggested that RAD52 may have clinical value as a prognostic marker of tumour response to neoadjuvant radiation and both disease-free status and overall survival in patients with rectal cancer.
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Affiliation(s)
- Vincent Ho
- School of Medicine, Western Sydney University, Campbelltown, NSW 2560, Australia; (L.C.); (A.A.); (T.L.R.); (P.d.S.); (C.S.L.)
- Correspondence: ; Tel.: +61-2-4620-3845; Fax: +61-2-4520-3116
| | - Liping Chung
- School of Medicine, Western Sydney University, Campbelltown, NSW 2560, Australia; (L.C.); (A.A.); (T.L.R.); (P.d.S.); (C.S.L.)
- Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia; (S.H.L.); (W.C.)
| | - Amandeep Singh
- Department of Anatomical Pathology, Liverpool Hospital, Liverpool, NSW 2170, Australia; (A.S.); (V.L.)
| | - Vivienne Lea
- Department of Anatomical Pathology, Liverpool Hospital, Liverpool, NSW 2170, Australia; (A.S.); (V.L.)
| | - Askar Abubakar
- School of Medicine, Western Sydney University, Campbelltown, NSW 2560, Australia; (L.C.); (A.A.); (T.L.R.); (P.d.S.); (C.S.L.)
- Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia; (S.H.L.); (W.C.)
| | - Stephanie H. Lim
- Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia; (S.H.L.); (W.C.)
- Macarthur Cancer Therapy Centre, Campbelltown Hospital, NSW 2560, Australia
- Discipline of Medical Oncology, School of Medicine, Western Sydney University, Liverpool, NSW 2170, Australia
| | - Wei Chua
- Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia; (S.H.L.); (W.C.)
- Department of Medical Oncology, Liverpool Hospital, Liverpool, NSW 2170, Australia;
- South Western Sydney Clinical School, University of New South Wales, Liverpool Hospital, Liverpool, NSW 2170, Australia
| | - Weng Ng
- Department of Medical Oncology, Liverpool Hospital, Liverpool, NSW 2170, Australia;
| | - Mark Lee
- Department of Radiation Oncology, Liverpool Hospital, Liverpool, NSW 2170, Australia;
| | - Tara L. Roberts
- School of Medicine, Western Sydney University, Campbelltown, NSW 2560, Australia; (L.C.); (A.A.); (T.L.R.); (P.d.S.); (C.S.L.)
- Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia; (S.H.L.); (W.C.)
- South Western Sydney Clinical School, University of New South Wales, Liverpool Hospital, Liverpool, NSW 2170, Australia
| | - Paul de Souza
- School of Medicine, Western Sydney University, Campbelltown, NSW 2560, Australia; (L.C.); (A.A.); (T.L.R.); (P.d.S.); (C.S.L.)
- Discipline of Medical Oncology, School of Medicine, Western Sydney University, Liverpool, NSW 2170, Australia
- Department of Medical Oncology, Liverpool Hospital, Liverpool, NSW 2170, Australia;
| | - Cheok Soon Lee
- School of Medicine, Western Sydney University, Campbelltown, NSW 2560, Australia; (L.C.); (A.A.); (T.L.R.); (P.d.S.); (C.S.L.)
- Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia; (S.H.L.); (W.C.)
- Department of Anatomical Pathology, Liverpool Hospital, Liverpool, NSW 2170, Australia; (A.S.); (V.L.)
- Department of Radiation Oncology, Liverpool Hospital, Liverpool, NSW 2170, Australia;
- Discipline of Pathology, School of Medicine, Western Sydney University, Campbelltown, NSW 2560, Australia
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16
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RAD52: Viral Friend or Foe? Cancers (Basel) 2020; 12:cancers12020399. [PMID: 32046320 PMCID: PMC7072633 DOI: 10.3390/cancers12020399] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 02/06/2020] [Accepted: 02/06/2020] [Indexed: 02/06/2023] Open
Abstract
Mammalian Radiation Sensitive 52 (RAD52) is a gene whose scientific reputation has recently seen a strong resurgence. In the past decade, RAD52, which was thought to be dispensable for most DNA repair and recombination reactions in mammals, has been shown to be important for a bevy of DNA metabolic pathways. One of these processes is termed break-induced replication (BIR), a mechanism that can be used to re-start broken replication forks and to elongate the ends of chromosomes in telomerase-negative cells. Viruses have historically evolved a myriad of mechanisms in which they either conscript cellular factors or, more frequently, inactivate them as a means to enable their own replication and survival. Recent data suggests that Adeno-Associated Virus (AAV) may replicate its DNA in a BIR-like fashion and/or utilize RAD52 to facilitate viral transduction and, as such, likely conscripts/requires the host RAD52 protein to promote its perpetuation.
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17
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Kohzaki M, Ootsuyama A, Sun L, Moritake T, Okazaki R. Human RECQL4 represses the RAD52-mediated single-strand annealing pathway after ionizing radiation or cisplatin treatment. Int J Cancer 2019; 146:3098-3113. [PMID: 31495919 DOI: 10.1002/ijc.32670] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 08/06/2019] [Accepted: 09/04/2019] [Indexed: 11/12/2022]
Abstract
Ionizing radiation (IR) and cisplatin are frequently used cancer treatments, although the mechanisms of error-prone DNA repair-mediated genomic instability after anticancer treatment are not fully clarified yet. RECQL4 mutations mainly in the C-terminal region of the RECQL4 gene lead to the cancer-predisposing Rothmund-Thomson syndrome, but the function of RECQL4ΔC (C-terminus deleted) in error-prone DNA repair remains unclear. We established several RECQL4ΔC cell lines and found that RECQL4ΔC cancer cells, but not RECQL4ΔC nontumorigenic cells, exhibited IR/cisplatin hypersensitivity. Notably, RECQL4ΔC cancer cells presented increased RPA2/RAD52 foci after cancer treatments. RECQL4ΔC HCT116 cells exhibited increased error-prone single-strand annealing (SSA) activity and decreased alternative end-joining activities, suggesting that RECQL4 regulates the DNA repair pathway choice at double-strand breaks. RAD52 depletion by siRNA or RAD52 inhibitors (5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside [AICAR], (-)-epigallocatechin [EGC]) or a RAD52-phenylalanine 79 aptamer significantly restrained the growth of RAD52-upregulated RECQL4ΔC HCT116 cells in vitro and in mouse xenografts. Remarkably, compared to single-agent cisplatin or EGC treatment, cisplatin followed by low-concentration EGC had a significant suppressive effect on RECQL4ΔC HCT116 cell growth in vivo. Together, the regimens targeting the RAD52-mediated SSA pathway after anticancer treatment may be applicable for cancer patients with RECQL4 gene mutations.
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Affiliation(s)
- Masaoki Kohzaki
- Department of Radiological Health Science, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Japan, Kitakyushu, Japan
| | - Akira Ootsuyama
- Department of Radiation Biology and Health, School of Medicine, University of Occupational and Environmental Health, Japan, Kitakyushu, Japan
| | - Lue Sun
- Department of Radiological Health Science, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Japan, Kitakyushu, Japan.,Health Research Institute, Department of Life Science and Biotechnology, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan
| | - Takashi Moritake
- Department of Radiological Health Science, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Japan, Kitakyushu, Japan
| | - Ryuji Okazaki
- Department of Radiological Health Science, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Japan, Kitakyushu, Japan
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18
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Kelso AA, Lopezcolorado FW, Bhargava R, Stark JM. Distinct roles of RAD52 and POLQ in chromosomal break repair and replication stress response. PLoS Genet 2019; 15:e1008319. [PMID: 31381562 PMCID: PMC6695211 DOI: 10.1371/journal.pgen.1008319] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 08/15/2019] [Accepted: 07/18/2019] [Indexed: 12/18/2022] Open
Abstract
Disrupting either the DNA annealing factor RAD52 or the A-family DNA polymerase POLQ can cause synthetic lethality with defects in BRCA1 and BRCA2, which are tumor suppressors important for homology-directed repair of DNA double-strand breaks (DSBs), and protection of stalled replication forks. A likely mechanism of this synthetic lethality is that RAD52 and/or POLQ are important for backup pathways for DSB repair and/or replication stress responses. The features of DSB repair events that require RAD52 vs. POLQ, and whether combined disruption of these factors causes distinct effects on genome maintenance, have been unclear. Using human U2OS cells, we generated a cell line with POLQ mutations upstream of the polymerase domain, a RAD52 knockout cell line, and a line with combined disruption of both genes. We also examined RAD52 and POLQ using RNA-interference. We find that combined disruption of RAD52 and POLQ causes at least additive hypersensitivity to cisplatin, and a synthetic reduction in replication fork restart velocity. We also examined the influence of RAD52 and POLQ on several DSB repair events. We find that RAD52 is particularly important for repair using ≥ 50 nt repeat sequences that flank the DSB, and that also involve removal of non-homologous sequences flanking the repeats. In contrast, POLQ is important for repair events using 6 nt (but not ≥ 18 nt) of flanking repeats that are at the edge of the break, as well as oligonucleotide microhomology-templated (i.e., 12-20 nt) repair events requiring nascent DNA synthesis. Finally, these factors show key distinctions with BRCA2, regarding effects on DSB repair events and response to stalled replication forks. These findings indicate that RAD52 and POLQ have distinct roles in genome maintenance, including for specific features of DSB repair events, such that combined disruption of these factors may be effective for genotoxin sensitization and/or synthetic lethal strategies.
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Affiliation(s)
- Andrew A. Kelso
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, California, United States of America
| | - Felicia Wednesday Lopezcolorado
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, California, United States of America
| | - Ragini Bhargava
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, California, United States of America
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, California, United States of America
| | - Jeremy M. Stark
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, California, United States of America
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, California, United States of America
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19
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Jalan M, Olsen KS, Powell SN. Emerging Roles of RAD52 in Genome Maintenance. Cancers (Basel) 2019; 11:E1038. [PMID: 31340507 PMCID: PMC6679097 DOI: 10.3390/cancers11071038] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 07/17/2019] [Accepted: 07/18/2019] [Indexed: 12/22/2022] Open
Abstract
The maintenance of genome integrity is critical for cell survival. Homologous recombination (HR) is considered the major error-free repair pathway in combatting endogenously generated double-stranded lesions in DNA. Nevertheless, a number of alternative repair pathways have been described as protectors of genome stability, especially in HR-deficient cells. One of the factors that appears to have a role in many of these pathways is human RAD52, a DNA repair protein that was previously considered to be dispensable due to a lack of an observable phenotype in knock-out mice. In later studies, RAD52 deficiency has been shown to be synthetically lethal with defects in BRCA genes, making RAD52 an attractive therapeutic target, particularly in the context of BRCA-deficient tumors.
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Affiliation(s)
- Manisha Jalan
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Kyrie S Olsen
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Simon N Powell
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
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20
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Graber-Feesl CL, Pederson KD, Aney KJ, Shima N. Mitotic DNA Synthesis Is Differentially Regulated between Cancer and Noncancerous Cells. Mol Cancer Res 2019; 17:1687-1698. [PMID: 31113828 DOI: 10.1158/1541-7786.mcr-19-0057] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 04/12/2019] [Accepted: 05/16/2019] [Indexed: 11/16/2022]
Abstract
Mitotic DNA synthesis is a recently discovered mechanism that resolves late replication intermediates, thereby supporting cell proliferation under replication stress. This unusual form of DNA synthesis occurs in the absence of RAD51 or BRCA2, which led to the identification of RAD52 as a key player in this process. Notably, mitotic DNA synthesis is predominantly observed at chromosome loci that colocalize with FANCD2 foci. However, the role of this protein in mitotic DNA synthesis remains largely unknown. In this study, we investigated the role of FANCD2 and its interplay with RAD52 in mitotic DNA synthesis using aphidicolin as a universal inducer of this process. After examining eight human cell lines, we provide evidence for FANCD2 rather than RAD52 as a fundamental supporter of mitotic DNA synthesis. In cancer cell lines, FANCD2 exerts this role independently of RAD52. Surprisingly, RAD52 is dispensable for mitotic DNA synthesis in noncancerous cell lines, but these cells strongly depend on FANCD2 for this process. Therefore, RAD52 functions selectively in cancer cells as a secondary regulator in addition to FANCD2 to facilitate mitotic DNA synthesis. As an alternative to aphidicolin, we found partial inhibition of origin licensing as an effective way to induce mitotic DNA synthesis preferentially in cancer cells. Importantly, cancer cells still perform mitotic DNA synthesis by dual regulation of FANCD2 and RAD52 under such conditions. IMPLICATIONS: These key differences in mitotic DNA synthesis between cancer and noncancerous cells advance our understanding of this mechanism and can be exploited for cancer therapies.
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Affiliation(s)
- Cari L Graber-Feesl
- Department of Genetics, Cell Biology and Development, University of Minnesota, at Twin Cities, Masonic Cancer Center, Minneapolis, Minnesota
| | - Kayla D Pederson
- Department of Genetics, Cell Biology and Development, University of Minnesota, at Twin Cities, Masonic Cancer Center, Minneapolis, Minnesota
| | - Katherine J Aney
- Department of Genetics, Cell Biology and Development, University of Minnesota, at Twin Cities, Masonic Cancer Center, Minneapolis, Minnesota
| | - Naoko Shima
- Department of Genetics, Cell Biology and Development, University of Minnesota, at Twin Cities, Masonic Cancer Center, Minneapolis, Minnesota.
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21
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Gu P, Jia S, Takasugi T, Smith E, Nandakumar J, Hendrickson E, Chang S. CTC1-STN1 coordinates G- and C-strand synthesis to regulate telomere length. Aging Cell 2018; 17:e12783. [PMID: 29774655 PMCID: PMC6052479 DOI: 10.1111/acel.12783] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2018] [Indexed: 02/01/2023] Open
Abstract
Coats plus (CP) is a rare autosomal recessive disorder caused by mutations in CTC1, a component of the CST (CTC1, STN1, and TEN1) complex important for telomere length maintenance. The molecular basis of how CP mutations impact upon telomere length remains unclear. The CP CTC1L1142H mutation has been previously shown to disrupt telomere maintenance. In this study, we used CRISPR/Cas9 to engineer this mutation into both alleles of HCT116 and RPE cells to demonstrate that CTC1:STN1 interaction is required to repress telomerase activity. CTC1L1142H interacts poorly with STN1, leading to telomerase‐mediated telomere elongation. Impaired interaction between CTC1L1142H:STN1 and DNA Pol‐α results in increased telomerase recruitment to telomeres and further telomere elongation, revealing that C:S binding to DNA Pol‐α is required to fully repress telomerase activity. CP CTC1 mutants that fail to interact with DNA Pol‐α resulted in loss of C‐strand maintenance and catastrophic telomere shortening. Our findings place the CST complex as an important regulator of both G‐strand extensions by telomerase and C‐strand synthesis by DNA Pol‐α.
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Affiliation(s)
- Peili Gu
- Department of Laboratory Medicine; Yale University School of Medicine; New Haven Connecticut
| | - Shuting Jia
- Lab of Molecular Genetics of Aging and Tumor; Faculty of Medicine; Kunming University of Science and Technology; Kunming Yunnan Province China
| | - Taylor Takasugi
- Department of Laboratory Medicine; Yale University School of Medicine; New Haven Connecticut
- Department of Biochemistry, Molecular Biology and Biophysics; University of Minnesota Medical School; Minneapolis Minnesota
| | - Eric Smith
- Department of Molecular, Cellular, and Developmental Biology; University of Michigan; Ann Arbor Michigan
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular, and Developmental Biology; University of Michigan; Ann Arbor Michigan
- Program in Chemical Biology; University of Michigan; Ann Arbor Michigan
| | - Eric Hendrickson
- Department of Biochemistry, Molecular Biology and Biophysics; University of Minnesota Medical School; Minneapolis Minnesota
| | - Sandy Chang
- Department of Laboratory Medicine; Yale University School of Medicine; New Haven Connecticut
- Department of Pathology; Yale University School of Medicine; New Haven Connecticut
- Molecular Biophysics and Biochemistry; Yale University School of Medicine; New Haven Connecticut
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22
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Andriuskevicius T, Kotenko O, Makovets S. Putting together and taking apart: assembly and disassembly of the Rad51 nucleoprotein filament in DNA repair and genome stability. Cell Stress 2018; 2:96-112. [PMID: 31225474 PMCID: PMC6551702 DOI: 10.15698/cst2018.05.134] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Homologous recombination is a key mechanism providing both genome stability and genetic diversity in all living organisms. Recombinases play a central role in this pathway: multiple protein subunits of Rad51 or its orthologues bind single-stranded DNA to form a nucleoprotein filament which is essential for initiating recombination events. Multiple factors are involved in the regulation of this step, both positively and negatively. In this review, we discuss Rad51 nucleoprotein assembly and disassembly, how it is regulated and what functional significance it has in genome maintenance.
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Affiliation(s)
| | - Oleksii Kotenko
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh
| | - Svetlana Makovets
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh
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