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Honda M, Razzaghi M, Gaur P, Malacaria E, Marozzi G, Biagi LD, Aiello FA, Paintsil EA, Stanfield AJ, Deppe BJ, Gakhar L, Schnicker NJ, Ashley Spies M, Pichierri P, Spies M. A double-ring of human RAD52 remodels replication forks restricting fork reversal. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.14.566657. [PMID: 38014173 PMCID: PMC10680749 DOI: 10.1101/2023.11.14.566657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Human RAD52 1,2 is a multifunctional DNA repair protein involved in several cellular events that support genome stability including protection of stalled DNA replication forks from excessive degradation 3-7 . In its gatekeeper role, RAD52 binds to and stabilizes stalled replication forks during replication stress protecting them from reversal by SMARCAL1 5 . The structural and molecular mechanism of the RAD52-mediated fork protection remains elusive. Here, using P1 nuclease sensitivity, biochemical and single-molecule analyses we show that RAD52 dynamically remodels replication forks through its strand exchange activity. The presence of the ssDNA binding protein RPA at the fork modulates the kinetics of the strand exchange without impeding the reaction outcome. Mass photometry and single-particle cryo-electron microscopy show that the replication fork promotes a unique nucleoprotein structure containing head-to-head arrangement of two undecameric RAD52 rings with an extended positively charged surface that accommodates all three arms of the replication fork. We propose that the formation and continuity of this surface is important for the strand exchange reaction and for competition with SMARCAL1. One Sentence Summary Using cryo-EM, biochemical and single-molecule approaches we show that the structure of stalled DNA replication fork promotes a unique two-ring organization of human RAD52 protein which remodels the fork via DNA strand exchange.
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2
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Struble LR, Lovelace JJ, Borgstahl GEO. A glimpse into the hidden world of the flexible C-terminal protein binding domains of human RAD52. J Struct Biol 2024; 216:108115. [PMID: 39117045 DOI: 10.1016/j.jsb.2024.108115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 07/25/2024] [Accepted: 08/04/2024] [Indexed: 08/10/2024]
Abstract
Human RAD52 protein binds DNA and is involved in genomic stability maintenance and several forms of DNA repair, including homologous recombination and single-strand annealing. Despite its importance, there are very few structural details about the variability of the RAD52 ring size and the RAD52 C-terminal protein-protein interaction domains. Even recent attempts to employ cryogenic electron microscopy (cryoEM) methods on full-length yeast and human RAD52 do not reveal interpretable structures for the C-terminal half that contains the replication protein A (RPA) and RAD51 binding domains. In this study, we employed the monodisperse purification of two RAD52 deletion constructs and small angle X-ray scattering (SAXS) to construct a structural model that includes RAD52's RPA binding domain. This model is of interest to DNA repair specialists as well as for drug development against HR-deficient cancers.
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Affiliation(s)
- Lucas R Struble
- The Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA
| | - Jeffrey J Lovelace
- The Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA
| | - Gloria E O Borgstahl
- The Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA.
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3
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Balboni B, Marotta R, Rinaldi F, Milordini G, Varignani G, Girotto S, Cavalli A. An integrative structural study of the human full-length RAD52 at 2.2 Å resolution. Commun Biol 2024; 7:956. [PMID: 39112549 PMCID: PMC11306251 DOI: 10.1038/s42003-024-06644-1] [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: 02/11/2024] [Accepted: 07/27/2024] [Indexed: 08/10/2024] Open
Abstract
Human RAD52 (RAD52) is a DNA-binding protein involved in many DNA repair mechanisms and genomic stability maintenance. In the last few years, this protein was discovered to be a promising novel pharmacological target for anticancer strategies. Although the interest in RAD52 has exponentially grown in the previous decade, most information about its structure and mechanism still needs to be elucidated. Here, we report the 2.2 Å resolution cryo-EM reconstruction of the full-length RAD52 (FL-RAD52) protein. This allows us to describe the hydration shell of the N-terminal region of FL-RAD52, which is structured in an undecamer ring. Water molecules coordinate with protein residues to promote stabilization inside and among the protomers and within the inner DNA binding cleft to drive protein-DNA recognition. Additionally, through a multidisciplinary approach involving SEC-SAXS and computational methods, we comprehensively describe the highly flexible and dynamic organization of the C-terminal portion of FL-RAD52. This work discloses unprecedented structural details on the FL-RAD52, which will be critical for characterizing its mechanism of action and inhibitor development, particularly in the context of novel approaches to synthetic lethality and anticancer drug discovery.
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Affiliation(s)
- Beatrice Balboni
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Genoa, Italy
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Roberto Marotta
- Electron Microscopy Facility (EMF), Istituto Italiano di Tecnologia, Genoa, Italy
| | - Francesco Rinaldi
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Genoa, Italy
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Giulia Milordini
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Giulia Varignani
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Genoa, Italy
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Stefania Girotto
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Genoa, Italy.
- Structural Biophysics Facility, Istituto Italiano di Tecnologia, Genoa, Italy.
| | - Andrea Cavalli
- Computational and Chemical Biology, Istituto Italiano di Tecnologia, Genoa, Italy.
- CECAM, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
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4
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Kumar M, Dubey R, Kumar Shukla P, Dayal D, Kumar Chaubey K, Tsai LW, Kumar S. Identification of small molecule inhibitors of RAD52 for breast cancer therapy: in silico approach. J Biomol Struct Dyn 2024; 42:4605-4618. [PMID: 37288783 DOI: 10.1080/07391102.2023.2220822] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 05/29/2023] [Indexed: 06/09/2023]
Abstract
The breast cancer susceptibility gene 1/2 (BRCA1/2) are the key regulators in maintaining the genomic integrity and mutations in these genes have been associated with development of breast and ovarian cancers. Also, synthetic lethality has been shown in BRCA1/2 deficient cancers, when the RAD52 gene is silenced by shRNA or small molecules aptamers, suggesting a role for RAD52 in the breast cancers pathogenesis. Thus, to find the potential inhibitors of RAD52, a collection of 21,000 compounds from the ChemBridge screening library was screened to conduct molecular docking and molecular dynamics simulation (MD) against RAD52. Further, the results were validated by a density functional theory (DFT) analysis and using post-dynamics free energy calculations. Out of all screened molecules, the docking study revealed five compounds were found to have promising activities against RAD52. Moreover, the catalytic amino acid residues of RAD52 developed stable contacts with compound 8758 and 10593, as anticipated by DFT calculation, MD simulation, and post dynamics MM-GBSA energy calculation. It appears that compound 8758 is the best inhibitor against RAD52 followed by 10593 compared to the other top hits, in terms of the HOMO orbital energy (-1.0966 eV and -1.2136 eV) from DFT and the post dynamics binding free energy calculation (-54.71 and -52.43 Kcal/mol). Furthermore, a drug-like properties of lead molecules (8758 and 10593) were also seen via ADMET analysis. Based on our computational analysis, we hypothesize that a small molecule 8758 and 10593 possess the therapeutic potential in the management for breast cancer patients with a BRCA mutation via targeting RAD52.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Mukesh Kumar
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Rajni Dubey
- Division of Cardiology, Department of Internal Medicine, Taipei Medical University Hospital, Taipei, Taiwan
| | - Prakash Kumar Shukla
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Deen Dayal
- Department of Biotechnology, GLA University, Mathura, Uttar Pradesh, India
| | - Kundan Kumar Chaubey
- Division of Research and Innovation, School of Applied and Life Sciences, Uttaranchal University, Dehradun, Uttarakhand, India
| | - Lung-Wen Tsai
- Department of Medicine Research, Taipei Medical University Hospital, Taipei, Taiwan
- Department of Information Technology Office, Taipei Medical University Hospital, Taipei, Taiwan
- Graduate Institute of Data Science, College of Management, Taipei Medical University, Taipei, Taiwan
| | - Sanjay Kumar
- Biological and Bio-computational Lab, Department of Life Sciences, Sharda School of Basic Science and Research, Sharda University, Greater Noida, Uttar Pradesh, India
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5
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Liang CC, Greenhough LA, Masino L, Maslen S, Bajrami I, Tuppi M, Skehel M, Taylor IA, West SC. Mechanism of single-stranded DNA annealing by RAD52-RPA complex. Nature 2024; 629:697-703. [PMID: 38658755 PMCID: PMC11096129 DOI: 10.1038/s41586-024-07347-7] [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: 06/06/2023] [Accepted: 03/22/2024] [Indexed: 04/26/2024]
Abstract
RAD52 is important for the repair of DNA double-stranded breaks1,2, mitotic DNA synthesis3-5 and alternative telomere length maintenance6,7. Central to these functions, RAD52 promotes the annealing of complementary single-stranded DNA (ssDNA)8,9 and provides an alternative to BRCA2/RAD51-dependent homologous recombination repair10. Inactivation of RAD52 in homologous-recombination-deficient BRCA1- or BRCA2-defective cells is synthetically lethal11,12, and aberrant expression of RAD52 is associated with poor cancer prognosis13,14. As a consequence, RAD52 is an attractive therapeutic target against homologous-recombination-deficient breast, ovarian and prostate cancers15-17. Here we describe the structure of RAD52 and define the mechanism of annealing. As reported previously18-20, RAD52 forms undecameric (11-subunit) ring structures, but these rings do not represent the active form of the enzyme. Instead, cryo-electron microscopy and biochemical analyses revealed that ssDNA annealing is driven by RAD52 open rings in association with replication protein-A (RPA). Atomic models of the RAD52-ssDNA complex show that ssDNA sits in a positively charged channel around the ring. Annealing is driven by the RAD52 N-terminal domains, whereas the C-terminal regions modulate the open-ring conformation and RPA interaction. RPA associates with RAD52 at the site of ring opening with critical interactions occurring between the RPA-interacting domain of RAD52 and the winged helix domain of RPA2. Our studies provide structural snapshots throughout the annealing process and define the molecular mechanism of ssDNA annealing by the RAD52-RPA complex.
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Affiliation(s)
| | | | | | | | | | - Marcel Tuppi
- The Francis Crick Institute, London, UK
- Abcam, Cambridge Biomedical Campus, Cambridge, UK
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6
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Lu M, Zhang X, Chu Q, Chen Y, Zhang P. Susceptibility Genes Associated with Multiple Primary Cancers. Cancers (Basel) 2023; 15:5788. [PMID: 38136334 PMCID: PMC10741435 DOI: 10.3390/cancers15245788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 11/29/2023] [Accepted: 12/05/2023] [Indexed: 12/24/2023] Open
Abstract
With advancements in treatment and screening techniques, we have been witnessing an era where more cancer survivors harbor multiple primary cancers (MPCs), affecting approximately one in six patients. Identifying MPCs is crucial for tumor staging and subsequent treatment choices. However, the current clinicopathological criteria for clinical application are limited and insufficient, making it challenging to differentiate them from recurrences or metastases. The emergence of next-generation sequencing (NGS) technology has provided a genetic perspective for defining multiple primary cancers. Researchers have found that, when considering multiple tumor pairs, it is crucial not only to examine well-known essential mutations like MLH1/MSH2, EGFR, PTEN, BRCA1/2, CHEK2, and TP53 mutations but also to explore certain pleiotropic loci. Moreover, specific deleterious mutations may serve as regulatory factors in second cancer development following treatment. This review aims to discuss these susceptibility genes and provide an explanation of their functions based on the signaling pathway background. Additionally, the association network between genetic signatures and different tumor pairs will be summarized.
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Affiliation(s)
| | | | | | | | - Peng Zhang
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; (M.L.)
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7
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Watson AJ, Shaffer ML, Bouley RA, Petreaca RC. F-box DNA Helicase 1 (FBH1) Contributes to the Destabilization of DNA Damage Repair Machinery in Human Cancers. Cancers (Basel) 2023; 15:4439. [PMID: 37760409 PMCID: PMC10526855 DOI: 10.3390/cancers15184439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 09/01/2023] [Accepted: 09/03/2023] [Indexed: 09/29/2023] Open
Abstract
Homologous recombination (HR) is the major mechanism of rescue of stalled replication forks or repair of DNA double-strand breaks (DSBs) during S phase or mitosis. In human cells, HR is facilitated by the BRCA2-BRCA1-PALB2 module, which loads the RAD51 recombinase onto a resected single-stranded DNA end to initiate repair. Although the process is essential for error-free repair, unrestrained HR can cause chromosomal rearrangements and genome instability. F-box DNA Helicase 1 (FBH1) antagonizes the role of BRCA2-BRCA1-PALB2 to restrict hyper-recombination and prevent genome instability. Here, we analyzed reported FBH1 mutations in cancer cells using the Catalogue of Somatic Mutations in Cancers (COSMIC) to understand how they interact with the BRCA2-BRCA1-PALB2. Consistent with previous results from yeast, we find that FBH1 mutations co-occur with BRCA2 mutations and to some degree BRCA1 and PALB2. We also describe some co-occurring mutations with RAD52, the accessory RAD51 loader and facilitator of single-strand annealing, which is independent of RAD51. In silico modeling was used to investigate the role of key FBH1 mutations on protein function, and a Q650K mutation was found to destabilize the protein structure. Taken together, this work highlights how mutations in several DNA damage repair genes contribute to cellular transformation and immortalization.
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Affiliation(s)
- Alizhah J. Watson
- Biology Program, The Ohio State University, Marion, OH 433023, USA; (A.J.W.); (M.L.S.)
| | - Michaela L. Shaffer
- Biology Program, The Ohio State University, Marion, OH 433023, USA; (A.J.W.); (M.L.S.)
| | - Renee A. Bouley
- Department of Chemistry and Biochemistry, The Ohio State University, Marion, OH 43302, USA
| | - Ruben C. Petreaca
- Department of Molecular Genetics, The Ohio State University, Marion, OH 43302, USA
- Cancer Biology Program, James Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
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8
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Riesenberg S, Kanis P, Macak D, Wollny D, Düsterhöft D, Kowalewski J, Helmbrecht N, Maricic T, Pääbo S. Efficient high-precision homology-directed repair-dependent genome editing by HDRobust. Nat Methods 2023; 20:1388-1399. [PMID: 37474806 PMCID: PMC10482697 DOI: 10.1038/s41592-023-01949-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 06/12/2023] [Indexed: 07/22/2023]
Abstract
Homology-directed repair (HDR), a method for repair of DNA double-stranded breaks can be leveraged for the precise introduction of mutations supplied by synthetic DNA donors, but remains limited by low efficiency and off-target effects. In this study, we report HDRobust, a high-precision method that, via the combined transient inhibition of nonhomologous end joining and microhomology-mediated end joining, resulted in the induction of point mutations by HDR in up to 93% (median 60%, s.e.m. 3) of chromosomes in populations of cells. We found that, using this method, insertions, deletions and rearrangements at the target site, as well as unintended changes at other genomic sites, were largely abolished. We validated this approach for 58 different target sites and showed that it allows efficient correction of pathogenic mutations in cells derived from patients suffering from anemia, sickle cell disease and thrombophilia.
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Affiliation(s)
- Stephan Riesenberg
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
| | - Philipp Kanis
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Dominik Macak
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Damian Wollny
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Dorothee Düsterhöft
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Johannes Kowalewski
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Nelly Helmbrecht
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Tomislav Maricic
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Svante Pääbo
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Human Evolutionary Genomics Unit, Okinawa Institute of Science and Technology, Onna-son, Japan
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9
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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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10
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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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11
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Pan-cancer analysis of co-occurring mutations in RAD52 and the BRCA1-BRCA2-PALB2 axis in human cancers. PLoS One 2022; 17:e0273736. [PMID: 36107942 PMCID: PMC9477347 DOI: 10.1371/journal.pone.0273736] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 08/12/2022] [Indexed: 11/19/2022] Open
Abstract
In human cells homologous recombination (HR) is critical for repair of DNA double strand breaks (DSBs) and rescue of stalled or collapsed replication forks. HR is facilitated by RAD51 which is loaded onto DNA by either BRCA2-BRCA1-PALB2 or RAD52. In human culture cells, double-knockdowns of RAD52 and genes in the BRCA1-BRCA2-PALB2 axis are lethal. Mutations in BRCA2, BRCA1 or PALB2 significantly impairs error free HR as RAD51 loading relies on RAD52 which is not as proficient as BRCA2-BRCA1-PALB2. RAD52 also facilitates Single Strand Annealing (SSA) that produces intra-chromosomal deletions. Some RAD52 mutations that affect the SSA function or decrease RAD52 association with DNA can suppress certain BRCA2 associated phenotypes in breast cancers. In this report we did a pan-cancer analysis using data reported on the Catalogue of Somatic Mutations in Cancers (COSMIC) to identify double mutants between RAD52 and BRCA1, BRCA2 or PALB2 that occur in cancer cells. We find that co-occurring mutations are likely in certain cancer tissues but not others. However, all mutations occur in a heterozygous state. Further, using computational and machine learning tools we identified only a handful of pathogenic or driver mutations predicted to significantly affect the function of the proteins. This supports previous findings that co-inactivation of RAD52 with any members of the BRCA2-BRCA1-PALB2 axis is lethal. Molecular modeling also revealed that pathogenic RAD52 mutations co-occurring with mutations in BRCA2-BRCA1-PALB2 axis are either expected to attenuate its SSA function or its interaction with DNA. This study extends previous breast cancer findings to other cancer types and shows that co-occurring mutations likely destabilize HR by similar mechanisms as in breast cancers.
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12
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OUP accepted manuscript. FEMS Yeast Res 2022; 22:6574410. [DOI: 10.1093/femsyr/foac021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 03/15/2022] [Accepted: 04/11/2022] [Indexed: 11/14/2022] Open
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13
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RPA phosphorylation facilitates RAD52 dependent homologous recombination in BRCA-deficient cells. Mol Cell Biol 2021; 42:e0052421. [PMID: 34928169 DOI: 10.1128/mcb.00524-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Loss of RAD52 is synthetically lethal in BRCA-deficient cells, owing to its role in backup homologous recombination (HR) repair of DNA double-strand breaks (DSBs). In HR in mammalian cells, DSBs are processed to single-stranded DNA (ssDNA) overhangs, which are then bound by Replication Protein A(RPA). RPA is exchanged for RAD51 by mediator proteins: in mammals BRCA2 is the primary mediator, however, RAD52 provides an alternative mediator pathway in BRCA-deficient cells. RAD51 stimulates strand exchange between homologous DNA duplexes, a critical step in HR. RPA phosphorylation and de-phosphorylation are important for HR, but its effect on RAD52 mediator function is unknown. Here, we show that RPA phosphorylation is required for RAD52 to salvage HR in BRCA-deficient cells. Using BRCA2-depleted human cells, in which the only available mediator pathway is RAD52-dependent, the expression of phosphorylation-deficient RPA mutant reduced HR. Furthermore, RPA-phospho-mutant cells showed reduced association of RAD52 with RAD51. Interestingly, there was no effect of RPA phosphorylation on RAD52 recruitment to repair foci. Finally, we show that RPA phosphorylation does not affect RAD52-dependent ssDNA annealing. Thus, although RAD52 can be recruited independently of RPA's phosphorylation status, RPA phosphorylation is required for RAD52's association with RAD51, and its subsequent promotion of RAD52-mediated HR.
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14
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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] [Grants] [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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Affiliation(s)
- Matthew J. Rossi
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
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15
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Yoshida K, Fujita M. DNA damage responses that enhance resilience to replication stress. Cell Mol Life Sci 2021; 78:6763-6773. [PMID: 34463774 PMCID: PMC11072782 DOI: 10.1007/s00018-021-03926-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/16/2021] [Accepted: 08/24/2021] [Indexed: 12/12/2022]
Abstract
During duplication of the genome, eukaryotic cells may experience various exogenous and endogenous replication stresses that impede progression of DNA replication along chromosomes. Chemical alterations in template DNA, imbalances of deoxynucleotide pools, repetitive sequences, tight DNA-protein complexes, and conflict with transcription can negatively affect the replication machineries. If not properly resolved, stalled replication forks can cause chromosome breaks leading to genomic instability and tumor development. Replication stress is enhanced in cancer cells due, for example, to the loss of DNA repair genes or replication-transcription conflict caused by activation of oncogenic pathways. To prevent these serious consequences, cells are equipped with diverse mechanisms that enhance the resilience of replication machineries to replication stresses. This review describes DNA damage responses activated at stressed replication forks and summarizes current knowledge on the pathways that promote faithful chromosome replication and protect chromosome integrity, including ATR-dependent replication checkpoint signaling, DNA cross-link repair, and SLX4-mediated responses to tight DNA-protein complexes that act as barriers. This review also focuses on the relevance of replication stress responses to selective cancer chemotherapies.
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Affiliation(s)
- Kazumasa Yoshida
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
- Department of Cell Biology, Faculty of Medicine, Fukuoka University, Fukuoka, 814-0180, Japan
- Central Research Institute for Advanced Molecular Medicine, Fukuoka University, Fukuoka, 814-0180, Japan
| | - Masatoshi Fujita
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
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16
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Llorens-Agost M, Ensminger M, Le HP, Gawai A, Liu J, Cruz-García A, Bhetawal S, Wood RD, Heyer WD, Löbrich M. POLθ-mediated end joining is restricted by RAD52 and BRCA2 until the onset of mitosis. Nat Cell Biol 2021; 23:1095-1104. [PMID: 34616022 PMCID: PMC8675436 DOI: 10.1038/s41556-021-00764-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 08/30/2021] [Indexed: 01/25/2023]
Abstract
BRCA2-mutant cells are defective in homologous recombination, making them vulnerable to the inactivation of other pathways for the repair of DNA double-strand breaks (DSBs). This concept can be clinically exploited but is currently limited due to insufficient knowledge about how DSBs are repaired in the absence of BRCA2. We show that DNA polymerase θ (POLθ)-mediated end joining (TMEJ) repairs DSBs arising during the S phase in BRCA2-deficient cells only after the onset of the ensuing mitosis. This process is regulated by RAD52, whose loss causes the premature usage of TMEJ and the formation of chromosomal fusions. Purified RAD52 and BRCA2 proteins both block the DNA polymerase function of POLθ, suggesting a mechanism explaining their synthetic lethal relationships. We propose that the delay of TMEJ until mitosis ensures the conversion of originally one-ended DSBs into two-ended DSBs. Mitotic chromatin condensation might further serve to juxtapose correct break ends and limit chromosomal fusions.
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Affiliation(s)
- Marta Llorens-Agost
- Radiation Biology and DNA Repair, Technical University of Darmstadt, Darmstadt, Germany
| | - Michael Ensminger
- Radiation Biology and DNA Repair, Technical University of Darmstadt, Darmstadt, Germany
| | - Hang Phuong Le
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA, USA
| | - Anugrah Gawai
- Radiation Biology and DNA Repair, Technical University of Darmstadt, Darmstadt, Germany
| | - Jie Liu
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA, USA
| | - Andrés Cruz-García
- Radiation Biology and DNA Repair, Technical University of Darmstadt, Darmstadt, Germany
| | - Sarita Bhetawal
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Smithville, TX, USA
| | - Richard D Wood
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Smithville, TX, USA
| | - Wolf-Dietrich Heyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA, USA
| | - Markus Löbrich
- Radiation Biology and DNA Repair, Technical University of Darmstadt, Darmstadt, Germany.
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17
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Su J, Xu R, Mongia P, Toyofuku N, Nakagawa T. Fission yeast Rad8/HLTF facilitates Rad52-dependent chromosomal rearrangements through PCNA lysine 107 ubiquitination. PLoS Genet 2021; 17:e1009671. [PMID: 34292936 PMCID: PMC8297803 DOI: 10.1371/journal.pgen.1009671] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 06/18/2021] [Indexed: 11/19/2022] Open
Abstract
Gross chromosomal rearrangements (GCRs), including translocation, deletion, and inversion, can cause cell death and genetic diseases such as cancer in multicellular organisms. Rad51, a DNA strand exchange protein, suppresses GCRs by repairing spontaneous DNA damage through a conservative way of homologous recombination, gene conversion. On the other hand, Rad52 that catalyzes single-strand annealing (SSA) causes GCRs using homologous sequences. However, the detailed mechanism of Rad52-dependent GCRs remains unclear. Here, we provide genetic evidence that fission yeast Rad8/HLTF facilitates Rad52-dependent GCRs through the ubiquitination of lysine 107 (K107) of PCNA, a DNA sliding clamp. In rad51Δ cells, loss of Rad8 eliminated 75% of the isochromosomes resulting from centromere inverted repeat recombination, showing that Rad8 is essential for the formation of the majority of isochromosomes in rad51Δ cells. Rad8 HIRAN and RING finger mutations reduced GCRs, suggesting that Rad8 facilitates GCRs through 3’ DNA-end binding and ubiquitin ligase activity. Mms2 and Ubc4 but not Ubc13 ubiquitin-conjugating enzymes were required for GCRs. Consistent with this, mutating PCNA K107 rather than the well-studied PCNA K164 reduced GCRs. Rad8-dependent PCNA K107 ubiquitination facilitates Rad52-dependent GCRs, as PCNA K107R, rad8, and rad52 mutations epistatically reduced GCRs. In contrast to GCRs, PCNA K107R did not significantly change gene conversion rates, suggesting a specific role of PCNA K107 ubiquitination in GCRs. PCNA K107R enhanced temperature-sensitive growth defects of DNA ligase I cdc17-K42 mutant, implying that PCNA K107 ubiquitination occurs when Okazaki fragment maturation fails. Remarkably, K107 is located at the interface between PCNA subunits, and an interface mutation D150E bypassed the requirement of PCNA K107 and Rad8 ubiquitin ligase for GCRs. These data suggest that Rad8-dependent PCNA K107 ubiquitination facilitates Rad52-dependent GCRs by changing the PCNA clamp structure. Gross chromosomal rearrangements (GCRs), including translocation, can alter gene dosage and activity, resulting in genetic diseases such as cancer. However, GCRs can occur by some enzymes, including Rad52 recombinase, and result in chromosomal evolution. Therefore, GCRs are not only pathological but also physiological phenomena from an evolutionary point of view. However, the detailed mechanism of GCRs remains unclear. Here, using fission yeast, we show that the homolog of human HLTF, Rad8 causes GCRs through noncanonical ubiquitination of proliferating cellular nuclear antigen (PCNA) at a lysine 107 (K107). Rad51, a DNA strand exchange protein, suppresses the formation of isochromosomes whose arms mirror each another and chromosomal truncation. We found that, like Rad52, Rad8 is required for isochromosome formation but not chromosomal truncation in rad51Δ cells, showing a specific role of Rad8 in homology-mediated GCRs. Mutations in Rad8 ubiquitin E3 ligase RING finger domain, Mms2-Ubc4 ubiquitin-conjugating enzymes, and PCNA K107 reduced GCRs in rad51Δ cells, suggesting that Rad8-Mms2-Ubc4-dependent PCNA K107 ubiquitination facilitates GCRs. PCNA trimers form a DNA sliding clamp. The K107 residue is located at the PCNA-PCNA interface, and an interface mutation D150E restored GCRs in PCNA K107R mutant cells. This study provides genetic evidence that Rad8-dependent PCNA K107 ubiquitination facilitates GCRs by changing the PCNA clamp structure.
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Affiliation(s)
- Jie Su
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Ran Xu
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Piyusha Mongia
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Naoko Toyofuku
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Takuro Nakagawa
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
- * E-mail:
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18
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Tatin X, Muggiolu G, Sauvaigo S, Breton J. Evaluation of DNA double-strand break repair capacity in human cells: Critical overview of current functional methods. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2021; 788:108388. [PMID: 34893153 DOI: 10.1016/j.mrrev.2021.108388] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 06/17/2021] [Accepted: 06/23/2021] [Indexed: 02/05/2023]
Abstract
DNA double-strand breaks (DSBs) are highly deleterious lesions, responsible for mutagenesis, chromosomal translocation or cell death. DSB repair (DSBR) is therefore a critical part of the DNA damage response (DDR) to restore molecular and genomic integrity. In humans, this process is achieved through different pathways with various outcomes. The balance between DSB repair activities varies depending on cell types, tissues or individuals. Over the years, several methods have been developed to study variations in DSBR capacity. Here, we mainly focus on functional techniques, which provide dynamic information regarding global DSB repair proficiency or the activity of specific pathways. These methods rely on two kinds of approaches. Indirect techniques, such as pulse field gel electrophoresis (PFGE), the comet assay and immunofluorescence (IF), measure DSB repair capacity by quantifying the time-dependent decrease in DSB levels after exposure to a DNA-damaging agent. On the other hand, cell-free assays and reporter-based methods directly track the repair of an artificial DNA substrate. Each approach has intrinsic advantages and limitations and despite considerable efforts, there is currently no ideal method to quantify DSBR capacity. All techniques provide different information and can be regarded as complementary, but some studies report conflicting results. Parameters such as the type of biological material, the required equipment or the cost of analysis may also limit available options. Improving currently available methods measuring DSBR capacity would be a major step forward and we present direct applications in mechanistic studies, drug development, human biomonitoring and personalized medicine, where DSBR analysis may improve the identification of patients eligible for chemo- and radiotherapy.
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Affiliation(s)
- Xavier Tatin
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 38000 Grenoble, France; LXRepair, 5 Avenue du Grand Sablon, 38700 La Tronche, France
| | | | - Sylvie Sauvaigo
- LXRepair, 5 Avenue du Grand Sablon, 38700 La Tronche, France
| | - Jean Breton
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 38000 Grenoble, France.
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19
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Tomasini PP, Guecheva TN, Leguisamo NM, Péricart S, Brunac AC, Hoffmann JS, Saffi J. Analyzing the Opportunities to Target DNA Double-Strand Breaks Repair and Replicative Stress Responses to Improve Therapeutic Index of Colorectal Cancer. Cancers (Basel) 2021; 13:3130. [PMID: 34201502 PMCID: PMC8268241 DOI: 10.3390/cancers13133130] [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: 05/06/2021] [Revised: 06/15/2021] [Accepted: 06/18/2021] [Indexed: 12/22/2022] Open
Abstract
Despite the ample improvements of CRC molecular landscape, the therapeutic options still rely on conventional chemotherapy-based regimens for early disease, and few targeted agents are recommended for clinical use in the metastatic setting. Moreover, the impact of cytotoxic, targeted agents, and immunotherapy combinations in the metastatic scenario is not fully satisfactory, especially the outcomes for patients who develop resistance to these treatments need to be improved. Here, we examine the opportunity to consider therapeutic agents targeting DNA repair and DNA replication stress response as strategies to exploit genetic or functional defects in the DNA damage response (DDR) pathways through synthetic lethal mechanisms, still not explored in CRC. These include the multiple actors involved in the repair of DNA double-strand breaks (DSBs) through homologous recombination (HR), classical non-homologous end joining (NHEJ), and microhomology-mediated end-joining (MMEJ), inhibitors of the base excision repair (BER) protein poly (ADP-ribose) polymerase (PARP), as well as inhibitors of the DNA damage kinases ataxia-telangiectasia and Rad3 related (ATR), CHK1, WEE1, and ataxia-telangiectasia mutated (ATM). We also review the biomarkers that guide the use of these agents, and current clinical trials with targeted DDR therapies.
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Affiliation(s)
- Paula Pellenz Tomasini
- Laboratory of Genetic Toxicology, Federal University of Health Sciences of Porto Alegre, Avenida Sarmento Leite, 245, Porto Alegre 90050-170, Brazil; (P.P.T.); (N.M.L.)
- Post-Graduation Program in Cell and Molecular Biology, Federal University of Rio Grande do Sul, Avenida Bento Gonçalves, 9500, Porto Alegre 91501-970, Brazil
| | - Temenouga Nikolova Guecheva
- Cardiology Institute of Rio Grande do Sul, University Foundation of Cardiology (IC-FUC), Porto Alegre 90620-000, Brazil;
| | - Natalia Motta Leguisamo
- Laboratory of Genetic Toxicology, Federal University of Health Sciences of Porto Alegre, Avenida Sarmento Leite, 245, Porto Alegre 90050-170, Brazil; (P.P.T.); (N.M.L.)
| | - Sarah Péricart
- Laboratoire D’Excellence Toulouse Cancer (TOUCAN), Laboratoire de Pathologie, Institut Universitaire du Cancer-Toulouse, Oncopole, 1 Avenue Irène-Joliot-Curie, 31059 Toulouse, France; (S.P.); (A.-C.B.); (J.S.H.)
| | - Anne-Cécile Brunac
- Laboratoire D’Excellence Toulouse Cancer (TOUCAN), Laboratoire de Pathologie, Institut Universitaire du Cancer-Toulouse, Oncopole, 1 Avenue Irène-Joliot-Curie, 31059 Toulouse, France; (S.P.); (A.-C.B.); (J.S.H.)
| | - Jean Sébastien Hoffmann
- Laboratoire D’Excellence Toulouse Cancer (TOUCAN), Laboratoire de Pathologie, Institut Universitaire du Cancer-Toulouse, Oncopole, 1 Avenue Irène-Joliot-Curie, 31059 Toulouse, France; (S.P.); (A.-C.B.); (J.S.H.)
| | - Jenifer Saffi
- Laboratory of Genetic Toxicology, Federal University of Health Sciences of Porto Alegre, Avenida Sarmento Leite, 245, Porto Alegre 90050-170, Brazil; (P.P.T.); (N.M.L.)
- Post-Graduation Program in Cell and Molecular Biology, Federal University of Rio Grande do Sul, Avenida Bento Gonçalves, 9500, Porto Alegre 91501-970, Brazil
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20
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Yang Q, Li Y, Sun R, Li J. Identification of a RAD52 Inhibitor Inducing Synthetic Lethality in BRCA2-Deficient Cancer Cells. Front Pharmacol 2021; 12:637825. [PMID: 33995041 PMCID: PMC8118686 DOI: 10.3389/fphar.2021.637825] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 04/12/2021] [Indexed: 11/16/2022] Open
Abstract
The breast cancer susceptibility gene 1/2 (BRCA1/2) is frequently mutated in many malignant tumors, such as breast cancer and ovarian cancer. Studies have demonstrated that inhibition of RAD52 gene function in BRCA2-deficient cancer causes synthetic lethality, suggesting a potential application of RAD52 in cancer-targeted therapy. In this study, we have performed a virtual screening by targeting the self-association domain (residues 85-159) of RAD52 with a library of 66,608 compounds and found one compound, C791-0064, that specifically inhibited the proliferation of BRCA2-deficient cancer cells. Our biochemical and cell-based experimental data suggested that C791-0064 specifically bound to RAD52 and disrupted the single-strand annealing activity of RAD52. Taken together, C791-0064 is a promising leading compound worthy of further exploitation in the context of BRCA-deficient targeted cancer therapy.
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Affiliation(s)
- Qianye Yang
- Institute of Cancer Biology and Drug Discovery, Chengdu University, Chengdu, China
- Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China
| | - Yu Li
- West China School of Pharmacy, Sichuan University, Chengdu, China
| | - Rong Sun
- Basic medical research center, School of medicine, Nantong University, Nantong, China
| | - Jian Li
- Institute of Cancer Biology and Drug Discovery, Chengdu University, Chengdu, China
- Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China
- School of Medicine, Chengdu University, Chengdu, China
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21
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Tseng WC, Chen CY, Chern CY, Wang CA, Lee WC, Chi YC, Cheng SF, Kuo YT, Chiu YC, Tseng ST, Lin PY, Liou SJ, Li YC, Chen CC. Targeting HR Repair as a Synthetic Lethal Approach to Increase DNA Damage Sensitivity by a RAD52 Inhibitor in BRCA2-Deficient Cancer Cells. Int J Mol Sci 2021; 22:4422. [PMID: 33922657 PMCID: PMC8122931 DOI: 10.3390/ijms22094422] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 04/21/2021] [Accepted: 04/22/2021] [Indexed: 02/01/2023] Open
Abstract
BRCA mutation, one of the most common types of mutations in breast and ovarian cancer, has been suggested to be synthetically lethal with depletion of RAD52. Pharmacologically inhibiting RAD52 specifically eradicates BRCA-deficient cancer cells. In this study, we demonstrated that curcumin, a plant polyphenol, sensitizes BRCA2-deficient cells to CPT-11 by impairing RAD52 recombinase in MCF7 cells. More specifically, in MCF7-siBRCA2 cells, curcumin reduced homologous recombination, resulting in tumor growth suppression. Furthermore, a BRCA2-deficient cell line, Capan1, became resistant to CPT-11 when BRCA2 was reintroduced. In vivo, xenograft model studies showed that curcumin combined with CPT-11 reduced the growth of BRCA2-knockout MCF7 tumors but not MCF7 tumors. In conclusion, our data indicate that curcumin, which has RAD52 inhibitor activity, is a promising candidate for sensitizing BRCA2-deficient cells to DNA damage-based cancer therapies.
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Affiliation(s)
- Wei-Che Tseng
- Graduate Institute of Natural Products, Chang Gung University, Taoyuan 333, Taiwan; (W.-C.T.); (S.-F.C.); (Y.-T.K.); (Y.-C.C.); (S.-T.T.); (P.-Y.L.); (S.-J.L.)
| | - Chi-Yuan Chen
- Tissue Bank, Chang Gung Memorial Hospital, Taoyuan 333, Taiwan;
- Graduate Institute of Health Industry Technology and Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan 333, Taiwan
| | - Ching-Yuh Chern
- Department of Applied Chemistry, National Chiayi University, Chiayi 600, Taiwan; (C.-Y.C.); (Y.-C.L.)
| | - Chu-An Wang
- Department of Physiology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan;
| | - Wen-Chih Lee
- Translational Research Program in Pediatric Orthopedics, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA;
| | - Ying-Chih Chi
- Cryo-EM Center, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY 10032, USA;
| | - Shu-Fang Cheng
- Graduate Institute of Natural Products, Chang Gung University, Taoyuan 333, Taiwan; (W.-C.T.); (S.-F.C.); (Y.-T.K.); (Y.-C.C.); (S.-T.T.); (P.-Y.L.); (S.-J.L.)
| | - Yi-Tsen Kuo
- Graduate Institute of Natural Products, Chang Gung University, Taoyuan 333, Taiwan; (W.-C.T.); (S.-F.C.); (Y.-T.K.); (Y.-C.C.); (S.-T.T.); (P.-Y.L.); (S.-J.L.)
| | - Ya-Chen Chiu
- Graduate Institute of Natural Products, Chang Gung University, Taoyuan 333, Taiwan; (W.-C.T.); (S.-F.C.); (Y.-T.K.); (Y.-C.C.); (S.-T.T.); (P.-Y.L.); (S.-J.L.)
| | - Shih-Ting Tseng
- Graduate Institute of Natural Products, Chang Gung University, Taoyuan 333, Taiwan; (W.-C.T.); (S.-F.C.); (Y.-T.K.); (Y.-C.C.); (S.-T.T.); (P.-Y.L.); (S.-J.L.)
| | - Pei-Ya Lin
- Graduate Institute of Natural Products, Chang Gung University, Taoyuan 333, Taiwan; (W.-C.T.); (S.-F.C.); (Y.-T.K.); (Y.-C.C.); (S.-T.T.); (P.-Y.L.); (S.-J.L.)
| | - Shou-Jhen Liou
- Graduate Institute of Natural Products, Chang Gung University, Taoyuan 333, Taiwan; (W.-C.T.); (S.-F.C.); (Y.-T.K.); (Y.-C.C.); (S.-T.T.); (P.-Y.L.); (S.-J.L.)
| | - Yi-Chen Li
- Department of Applied Chemistry, National Chiayi University, Chiayi 600, Taiwan; (C.-Y.C.); (Y.-C.L.)
| | - Chin-Chuan Chen
- Graduate Institute of Natural Products, Chang Gung University, Taoyuan 333, Taiwan; (W.-C.T.); (S.-F.C.); (Y.-T.K.); (Y.-C.C.); (S.-T.T.); (P.-Y.L.); (S.-J.L.)
- Tissue Bank, Chang Gung Memorial Hospital, Taoyuan 333, Taiwan;
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22
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Patel PS, Algouneh A, Hakem R. Exploiting synthetic lethality to target BRCA1/2-deficient tumors: where we stand. Oncogene 2021; 40:3001-3014. [PMID: 33716297 DOI: 10.1038/s41388-021-01744-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 02/21/2021] [Accepted: 02/26/2021] [Indexed: 12/11/2022]
Abstract
The principle of synthetic lethality, which refers to the loss of viability resulting from the disruption of two genes, which, individually, do not cause lethality, has become an attractive target approach due to the development and clinical success of Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi). In this review, we present the most recent findings on the use of PARPi in the clinic, which are currently approved for second-line therapy for advanced ovarian and breast cancer associated with mutations of BRCA1 or BRCA2 (BRCA1/2) genes. PARPi efficacy, however, appears to be limited by acquired and inherent resistance, highlighting the need for alternative and synergistic targets to eliminate these tumors. Here, we explore other identified synthetic lethal interactors of BRCA1/2, including DNA polymerase theta (POLQ), Fanconi anemia complementation group D2 (FANDC2), radiation sensitive 52 (RAD52), Flap structure-specific endonuclease 1 (FEN1), and apurinic/apyrimidinic endodeoxyribonuclease 2 (APE2), as well as other protein and nonprotein targets, for BRCA1/2-mutated cancers and their implications for future therapies. A wealth of information now exists for phenotypic and functional characterization of these novel synthetic lethal interactors of BRCA1/2, and leveraging these findings can pave the way for the development of new targeted therapies for patients suffering from these cancers.
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Affiliation(s)
- Parasvi S Patel
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Arash Algouneh
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Razq Hakem
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada.
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
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23
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Al-Mugotir M, Lovelace JJ, George J, Bessho M, Pal D, Struble L, Kolar C, Rana S, Natarajan A, Bessho T, Borgstahl GEO. Selective killing of homologous recombination-deficient cancer cell lines by inhibitors of the RPA:RAD52 protein-protein interaction. PLoS One 2021; 16:e0248941. [PMID: 33784323 DOI: 10.1371/journal.pone.0248941] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 03/09/2021] [Indexed: 12/29/2022] Open
Abstract
Synthetic lethality is a successful strategy employed to develop selective chemotherapeutics against cancer cells. Inactivation of RAD52 is synthetically lethal to homologous recombination (HR) deficient cancer cell lines. Replication protein A (RPA) recruits RAD52 to repair sites, and the formation of this protein-protein complex is critical for RAD52 activity. To discover small molecules that inhibit the RPA:RAD52 protein-protein interaction (PPI), we screened chemical libraries with our newly developed Fluorescence-based protein-protein Interaction Assay (FluorIA). Eleven compounds were identified, including FDA-approved drugs (quinacrine, mitoxantrone, and doxorubicin). The FluorIA was used to rank the compounds by their ability to inhibit the RPA:RAD52 PPI and showed mitoxantrone and doxorubicin to be the most effective. Initial studies using the three FDA-approved drugs showed selective killing of BRCA1-mutated breast cancer cells (HCC1937), BRCA2-mutated ovarian cancer cells (PE01), and BRCA1-mutated ovarian cancer cells (UWB1.289). It was noteworthy that selective killing was seen in cells known to be resistant to PARP inhibitors (HCC1937 and UWB1 SYr13). A cell-based double-strand break (DSB) repair assay indicated that mitoxantrone significantly suppressed RAD52-dependent single-strand annealing (SSA) and mitoxantrone treatment disrupted the RPA:RAD52 PPI in cells. Furthermore, mitoxantrone reduced radiation-induced foci-formation of RAD52 with no significant activity against RAD51 foci formation. The results indicate that the RPA:RAD52 PPI could be a therapeutic target for HR-deficient cancers. These data also suggest that RAD52 is one of the targets of mitoxantrone and related compounds.
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Affiliation(s)
- Mona Al-Mugotir
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Jeffrey J Lovelace
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Joseph George
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Mika Bessho
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Dhananjaya Pal
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Lucas Struble
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Carol Kolar
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Sandeep Rana
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Amarnath Natarajan
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Tadayoshi Bessho
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Gloria E O Borgstahl
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
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Hanamshet K, Mazin AV. The function of RAD52 N-terminal domain is essential for viability of BRCA-deficient cells. Nucleic Acids Res 2021; 48:12778-12791. [PMID: 33275133 PMCID: PMC7736796 DOI: 10.1093/nar/gkaa1145] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 11/03/2020] [Accepted: 11/09/2020] [Indexed: 02/06/2023] Open
Abstract
RAD52 is a member of the homologous recombination pathway that is important for survival of BRCA-deficient cells. Inhibition of RAD52 leads to lethality in BRCA-deficient cells. However, the exact mechanism of how RAD52 contributes to viability of BRCA-deficient cells remains unknown. Two major activities of RAD52 were previously identified: DNA or RNA pairing, which includes DNA/RNA annealing and strand exchange, and mediator, which is to assist RAD51 loading on RPA-covered ssDNA. Here, we report that the N-terminal domain (NTD) of RAD52 devoid of the potential mediator function is essential for maintaining viability of BRCA-deficient cells owing to its ability to promote DNA/RNA pairing. We show that RAD52 NTD forms nuclear foci upon DNA damage in BRCA-deficient human cells and promotes DNA double-strand break repair through two pathways: homology-directed repair (HDR) and single-strand annealing (SSA). Furthermore, we show that mutations in the RAD52 NTD that disrupt these activities fail to maintain viability of BRCA-deficient cells.
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Affiliation(s)
- Kritika Hanamshet
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
| | - Alexander V Mazin
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
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25
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Whelan DR, Lee WTC, Marks F, Kong YT, Yin Y, Rothenberg E. Super-resolution visualization of distinct stalled and broken replication fork structures. PLoS Genet 2020; 16:e1009256. [PMID: 33370257 PMCID: PMC7793303 DOI: 10.1371/journal.pgen.1009256] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 01/08/2021] [Accepted: 11/03/2020] [Indexed: 12/25/2022] Open
Abstract
Endogenous genotoxic stress occurs in healthy cells due to competition between DNA replication machinery, and transcription and topographic relaxation processes. This causes replication fork stalling and regression, which can further collapse to form single-ended double strand breaks (seDSBs). Super-resolution microscopy has made it possible to directly observe replication stress and DNA damage inside cells, however new approaches to sample preparation and analysis are required. Here we develop and apply multicolor single molecule microscopy to visualize individual replication forks under mild stress from the trapping of Topoisomerase I cleavage complexes, a damage induction which closely mimics endogenous replicative stress. We observe RAD51 and RAD52, alongside RECQ1, as the first responder proteins to stalled but unbroken forks, whereas Ku and MRE11 are initially recruited to seDSBs. By implementing novel super-resolution imaging assays, we are thus able to discern closely related replication fork stress motifs and their repair pathways.
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Affiliation(s)
- Donna R. Whelan
- Department of Pharmacy and Biomedical Sciences, La Trobe Institute for Molecular Science, La Trobe University, Bendigo, Victoria, Australia
- * E-mail: (DRW); (ER)
| | - Wei Ting C. Lee
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, New York, United States of America
| | - Frances Marks
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, New York, United States of America
| | - Yu Tina Kong
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, New York, United States of America
| | - Yandong Yin
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, New York, United States of America
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, New York, United States of America
- * E-mail: (DRW); (ER)
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26
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27
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Onaka AT, Su J, Katahira Y, Tang C, Zafar F, Aoki K, Kagawa W, Niki H, Iwasaki H, Nakagawa T. DNA replication machinery prevents Rad52-dependent single-strand annealing that leads to gross chromosomal rearrangements at centromeres. Commun Biol 2020; 3:202. [PMID: 32355220 PMCID: PMC7193609 DOI: 10.1038/s42003-020-0934-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 04/09/2020] [Indexed: 12/27/2022] Open
Abstract
Homologous recombination between repetitive sequences can lead to gross chromosomal rearrangements (GCRs). At fission yeast centromeres, Rad51-dependent conservative recombination predominantly occurs between inverted repeats, thereby suppressing formation of isochromosomes whose arms are mirror images. However, it is unclear how GCRs occur in the absence of Rad51 and how GCRs are prevented at centromeres. Here, we show that homology-mediated GCRs occur through Rad52-dependent single-strand annealing (SSA). The rad52-R45K mutation, which impairs SSA activity of Rad52 protein, dramatically reduces isochromosome formation in rad51 deletion cells. A ring-like complex Msh2-Msh3 and a structure-specific endonuclease Mus81 function in the Rad52-dependent GCR pathway. Remarkably, mutations in replication fork components, including DNA polymerase α and Swi1/Tof1/Timeless, change the balance between Rad51-dependent recombination and Rad52-dependent SSA at centromeres, increasing Rad52-dependent SSA that forms isochromosomes. Our results uncover a role of DNA replication machinery in the recombination pathway choice that prevents Rad52-dependent GCRs at centromeres.
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Affiliation(s)
- Atsushi T Onaka
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan.,Chitose Laboratory Corporation, 2-13-3 Nogawa-honcho, Miyamae-ku, Kawasaki, Kanagawa, 216-0041, Japan
| | - Jie Su
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Yasuhiro Katahira
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan.,Department of Immunoregulation, Institute of Medical Science, Tokyo Medical University, 6-1-1 Shinjuku-ku, Tokyo, 160-8402, Japan
| | - Crystal Tang
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Faria Zafar
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Keita Aoki
- Microbial Physiology Laboratory, Department of Gene Function and Phenomics, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka, 411-8540, Japan
| | - Wataru Kagawa
- Department of Chemistry, Graduate School of Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo, 191-8506, Japan
| | - Hironori Niki
- Microbial Physiology Laboratory, Department of Gene Function and Phenomics, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka, 411-8540, Japan
| | - Hiroshi Iwasaki
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan
| | - Takuro Nakagawa
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan.
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28
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Physiological and Pathological Roles of RAD52 at DNA Replication Forks. Cancers (Basel) 2020; 12:cancers12020402. [PMID: 32050645 PMCID: PMC7072239 DOI: 10.3390/cancers12020402] [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: 01/08/2020] [Revised: 02/06/2020] [Accepted: 02/07/2020] [Indexed: 02/07/2023] Open
Abstract
Understanding basic molecular mechanisms underlying the biology of cancer cells is of outmost importance for identification of novel therapeutic targets and biomarkers for patient stratification and better therapy selection. One of these mechanisms, the response to replication stress, fuels cancer genomic instability. It is also an Achille’s heel of cancer. Thus, identification of pathways used by the cancer cells to respond to replication-stress may assist in the identification of new biomarkers and discovery of new therapeutic targets. Alternative mechanisms that act at perturbed DNA replication forks and involve fork degradation by nucleases emerged as crucial for sensitivity of cancer cells to chemotherapeutics agents inducing replication stress. Despite its important role in homologous recombination and recombinational repair of DNA double strand breaks in lower eukaryotes, RAD52 protein has been considered dispensable in human cells and the full range of its cellular functions remained unclear. Very recently, however, human RAD52 emerged as an important player in multiple aspects of replication fork metabolism under physiological and pathological conditions. In this review, we describe recent advances on RAD52’s key functions at stalled or collapsed DNA replication forks, in particular, the unexpected role of RAD52 as a gatekeeper, which prevents unscheduled processing of DNA. Last, we will discuss how these functions can be exploited using specific inhibitors in targeted therapy or for an informed therapy selection.
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29
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Lim G, Chang Y, Huh WK. Phosphoregulation of Rad51/Rad52 by CDK1 functions as a molecular switch for cell cycle-specific activation of homologous recombination. SCIENCE ADVANCES 2020; 6:eaay2669. [PMID: 32083180 PMCID: PMC7007264 DOI: 10.1126/sciadv.aay2669] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 11/25/2019] [Indexed: 06/10/2023]
Abstract
Homologous recombination is exquisitely activated only during specific cell phases. In the G1 phase, homologous recombination activity is completely suppressed. According to previous reports, the activation of homologous recombination during specific cell phases depends on the kinase activity of cyclin-dependent kinase 1 (CDK1). However, the precise regulatory mechanism and target substrates of CDK1 for this regulation have not been completely determined. Here, we report that the budding yeast CDK1, Cdc28, phosphorylates the major homologous recombination regulators Rad51 and Rad52. This phosphorylation occurs in the G2/M phase by Cdc28 in combination with G2/M phase cyclins. Nonphosphorylatable mutations in Rad51 and Rad52 impair the DNA binding affinity of Rad51 and the affinity between Rad52 rings that leads to their interaction. Collectively, our data provide detailed insights into the regulatory mechanism of cell cycle-dependent homologous recombination activation in eukaryotic cells.
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Affiliation(s)
- Gyubum Lim
- School of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Yeonji Chang
- Institute of Microbiology, Seoul National University, Seoul 08826, Republic of Korea
| | - Won-Ki Huh
- School of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
- Institute of Microbiology, Seoul National University, Seoul 08826, Republic of Korea
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30
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Role of Rad51 and DNA repair in cancer: A molecular perspective. Pharmacol Ther 2020; 208:107492. [PMID: 32001312 DOI: 10.1016/j.pharmthera.2020.107492] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 01/13/2020] [Accepted: 01/22/2020] [Indexed: 12/24/2022]
Abstract
The maintenance of genome integrity is essential for any organism survival and for the inheritance of traits to offspring. To the purpose, cells have developed a complex DNA repair system to defend the genetic information against both endogenous and exogenous sources of damage. Accordingly, multiple repair pathways can be aroused from the diverse forms of DNA lesions, which can be effective per se or via crosstalk with others to complete the whole DNA repair process. Deficiencies in DNA healing resulting in faulty repair and/or prolonged DNA damage can lead to genes mutations, chromosome rearrangements, genomic instability, and finally carcinogenesis and/or cancer progression. Although it might seem paradoxical, at the same time such defects in DNA repair pathways may have therapeutic implications for potential clinical practice. Here we provide an overview of the main DNA repair pathways, with special focus on the role played by homologous repair and the RAD51 recombinase protein in the cellular DNA damage response. We next discuss the recombinase structure and function per se and in combination with all its principal mediators and regulators. Finally, we conclude with an analysis of the manifold roles that RAD51 plays in carcinogenesis, cancer progression and anticancer drug resistance, and conclude this work with a survey of the most promising therapeutic strategies aimed at targeting RAD51 in experimental oncology.
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31
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Owens JL, Beketova E, Liu S, Tinsley SL, Asberry AM, Deng X, Huang J, Li C, Wan J, Hu CD. PRMT5 Cooperates with pICln to Function as a Master Epigenetic Activator of DNA Double-Strand Break Repair Genes. iScience 2019; 23:100750. [PMID: 31884170 PMCID: PMC6941881 DOI: 10.1016/j.isci.2019.100750] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 11/06/2019] [Accepted: 11/22/2019] [Indexed: 01/21/2023] Open
Abstract
DNA double-strand break (DSB) repair is critical for cell survival and genome integrity. Upon recognition of DSBs, repair proteins are transiently upregulated to facilitate repair through homologous recombination (HR) or non-homologous end joining (NHEJ). We present evidence that PRMT5 cooperates with pICln to function as a master epigenetic activator of DNA damage response (DDR) genes involved in HR, NHEJ, and G2 arrest (including RAD51, BRCA1, and BRCA2) to upregulate gene expression upon DNA damage. Contrary to the predominant role of PRMT5 as an epigenetic repressor, our results demonstrate that PRMT5 and pICln can activate gene expression, potentially independent of PRMT5's obligate cofactor MEP50. Targeting PRMT5 or pICln hinders repair of DSBs in multiple cancer cell lines, and both PRMT5 and pICln expression positively correlates with DDR genes across 32 clinical cancer datasets. Thus, targeting PRMT5 or pICln may be explored in combination with radiation or chemotherapy for cancer treatment. PRMT5 activates transcription of DSB repair genes upon DNA damage pICln cooperates with PRMT5 to activate transcription of DSB repair genes Targeting PRMT5 is effective to sensitize multiple cancer types to radiation PRMT5 expression positively correlates with DSB repair genes in cancer tissues
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Affiliation(s)
- Jake L Owens
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
| | - Elena Beketova
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA; Purdue University Interdisciplinary Life Sciences Graduate Program, Purdue University, West Lafayette, IN 47907, USA
| | - Sheng Liu
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA; The Indiana University Melvin and Bren Simon Cancer Center, Indiana University, Indianapolis, IN 46202, USA
| | - Samantha L Tinsley
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA; Purdue University Interdisciplinary Life Sciences Graduate Program, Purdue University, West Lafayette, IN 47907, USA
| | - Andrew M Asberry
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA; Purdue University Interdisciplinary Life Sciences Graduate Program, Purdue University, West Lafayette, IN 47907, USA
| | - Xuehong Deng
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
| | - Jiaoti Huang
- Department of Pathology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Chenglong Li
- Department of Medicinal Chemistry, University of Florida College of Pharmacy, Gainesville, FL 32610, USA
| | - Jun Wan
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA; The Indiana University Melvin and Bren Simon Cancer Center, Indiana University, Indianapolis, IN 46202, USA; The Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, IN 46202, USA; Department of BioHealth Informatics, Indiana University School of Informatics and Computing, Indiana University - Purdue University Indianapolis, Indianapolis, IN 46202, USA.
| | - Chang-Deng Hu
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA; Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
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32
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Brieba LG. Structure-Function Analysis Reveals the Singularity of Plant Mitochondrial DNA Replication Components: A Mosaic and Redundant System. PLANTS 2019; 8:plants8120533. [PMID: 31766564 PMCID: PMC6963530 DOI: 10.3390/plants8120533] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 02/06/2023]
Abstract
Plants are sessile organisms, and their DNA is particularly exposed to damaging agents. The integrity of plant mitochondrial and plastid genomes is necessary for cell survival. During evolution, plants have evolved mechanisms to replicate their mitochondrial genomes while minimizing the effects of DNA damaging agents. The recombinogenic character of plant mitochondrial DNA, absence of defined origins of replication, and its linear structure suggest that mitochondrial DNA replication is achieved by a recombination-dependent replication mechanism. Here, I review the mitochondrial proteins possibly involved in mitochondrial DNA replication from a structural point of view. A revision of these proteins supports the idea that mitochondrial DNA replication could be replicated by several processes. The analysis indicates that DNA replication in plant mitochondria could be achieved by a recombination-dependent replication mechanism, but also by a replisome in which primers are synthesized by three different enzymes: Mitochondrial RNA polymerase, Primase-Helicase, and Primase-Polymerase. The recombination-dependent replication model and primers synthesized by the Primase-Polymerase may be responsible for the presence of genomic rearrangements in plant mitochondria.
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Affiliation(s)
- Luis Gabriel Brieba
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato, Guanajuato C.P. 36821, Mexico
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33
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Nogueira A, Fernandes M, Catarino R, Medeiros R. RAD52 Functions in Homologous Recombination and Its Importance on Genomic Integrity Maintenance and Cancer Therapy. Cancers (Basel) 2019; 11:E1622. [PMID: 31652722 PMCID: PMC6893724 DOI: 10.3390/cancers11111622] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 10/18/2019] [Accepted: 10/21/2019] [Indexed: 01/27/2023] Open
Abstract
Genomes are continually subjected to DNA damage whether they are induced from intrinsic physiological processes or extrinsic agents. Double-stranded breaks (DSBs) are the most injurious type of DNA damage, being induced by ionizing radiation (IR) and cytotoxic agents used in cancer treatment. The failure to repair DSBs can result in aberrant chromosomal abnormalities which lead to cancer development. An intricate network of DNA damage signaling pathways is usually activated to eliminate these damages and to restore genomic stability. These signaling pathways include the activation of cell cycle checkpoints, DNA repair mechanisms, and apoptosis induction, also known as DNA damage response (DDR)-mechanisms. Remarkably, the homologous recombination (HR) is the major DSBs repairing pathway, in which RAD52 gene has a crucial repairing role by promoting the annealing of complementary single-stranded DNA and by stimulating RAD51 recombinase activity. Evidence suggests that variations in RAD52 expression can influence HR activity and, subsequently, influence the predisposition and treatment efficacy of cancer. In this review, we present several reports in which the down or upregulation of RAD52 seems to be associated with different carcinogenic processes. In addition, we discuss RAD52 inhibition in DDR-defective cancers as a possible target to improve cancer therapy efficacy.
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Affiliation(s)
- Augusto Nogueira
- Molecular Oncology and Viral Pathology Group, IPO-Porto Research Center (CI-IPOP), Portuguese Institute of Oncology of Porto, 4200-072 Porto, Portugal.
- Faculty of Medicine of University of Porto (FMUP), 4200-319 Porto, Portugal.
| | - Mara Fernandes
- Molecular Oncology and Viral Pathology Group, IPO-Porto Research Center (CI-IPOP), Portuguese Institute of Oncology of Porto, 4200-072 Porto, Portugal.
- Faculty of Medicine of University of Porto (FMUP), 4200-319 Porto, Portugal.
| | - Raquel Catarino
- Molecular Oncology and Viral Pathology Group, IPO-Porto Research Center (CI-IPOP), Portuguese Institute of Oncology of Porto, 4200-072 Porto, Portugal.
| | - Rui Medeiros
- Molecular Oncology and Viral Pathology Group, IPO-Porto Research Center (CI-IPOP), Portuguese Institute of Oncology of Porto, 4200-072 Porto, Portugal.
- Faculty of Medicine of University of Porto (FMUP), 4200-319 Porto, Portugal.
- Biomedical Research Center (CEBIMED), Faculty of Health Sciences of Fernando Pessoa University, 4249-004 Porto, Portugal.
- Research Department, Portuguese League against Cancer (NRNorte), 4200-172 Porto, Portugal.
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34
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Toma M, Sullivan-Reed K, Śliwiński T, Skorski T. RAD52 as a Potential Target for Synthetic Lethality-Based Anticancer Therapies. Cancers (Basel) 2019; 11:E1561. [PMID: 31615159 PMCID: PMC6827130 DOI: 10.3390/cancers11101561] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 10/11/2019] [Accepted: 10/11/2019] [Indexed: 12/15/2022] Open
Abstract
Alterations in DNA repair systems play a key role in the induction and progression of cancer. Tumor-specific defects in DNA repair mechanisms and activation of alternative repair routes create the opportunity to employ a phenomenon called "synthetic lethality" to eliminate cancer cells. Targeting the backup pathways may amplify endogenous and drug-induced DNA damage and lead to specific eradication of cancer cells. So far, the synthetic lethal interaction between BRCA1/2 and PARP1 has been successfully applied as an anticancer treatment. Although PARP1 constitutes a promising target in the treatment of tumors harboring deficiencies in BRCA1/2-mediated homologous recombination (HR), some tumor cells survive, resulting in disease relapse. It has been suggested that alternative RAD52-mediated HR can protect BRCA1/2-deficient cells from the accumulation of DNA damage and the synthetic lethal effect of PARPi. Thus, simultaneous inhibition of RAD52 and PARP1 might result in a robust dual synthetic lethality, effectively eradicating BRCA1/2-deficient tumor cells. In this review, we will discuss the role of RAD52 and its potential application in synthetic lethality-based anticancer therapies.
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Affiliation(s)
- Monika Toma
- Sol Sherry Thrombosis Research Center and Fels Institute for Cancer Research and Molecular Biology Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA.
- Laboratory of Medical Genetics Faculty of Biology and Environmental Protection, University of Lodz, 90-236 Lodz, Poland.
| | - Katherine Sullivan-Reed
- Sol Sherry Thrombosis Research Center and Fels Institute for Cancer Research and Molecular Biology Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA.
| | - Tomasz Śliwiński
- Laboratory of Medical Genetics Faculty of Biology and Environmental Protection, University of Lodz, 90-236 Lodz, Poland.
| | - Tomasz Skorski
- Sol Sherry Thrombosis Research Center and Fels Institute for Cancer Research and Molecular Biology Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA.
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35
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Affiliation(s)
- Sanum Bashir
- The Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
| | - Ralf Kühn
- The Max-Delbrück-Center for Molecular Medicine, Berlin, Germany.
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36
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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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37
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Min J, Wright WE, Shay JW. Clustered telomeres in phase-separated nuclear condensates engage mitotic DNA synthesis through BLM and RAD52. Genes Dev 2019; 33:814-827. [PMID: 31171703 PMCID: PMC6601508 DOI: 10.1101/gad.324905.119] [Citation(s) in RCA: 119] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 04/24/2019] [Indexed: 11/25/2022]
Abstract
Alternative lengthening of telomeres (ALT) is a telomerase-independent telomere maintenance mechanism that occurs in a subset of cancers. One of the hallmarks of ALT cancer is the excessively clustered telomeres in promyelocytic leukemia (PML) bodies, represented as large bright telomere foci. Here, we present a model system that generates telomere clustering in nuclear polySUMO (small ubiquitin-like modification)/polySIM (SUMO-interacting motif) condensates, analogous to PML bodies, and thus artificially engineered ALT-associated PML body (APB)-like condensates in vivo. We observed that the ALT-like phenotypes (i.e., a small fraction of heterogeneous telomere lengths and formation of C circles) are rapidly induced by introducing the APB-like condensates together with BLM through its helicase domain, accompanied by ssDNA generation and RPA accumulation at telomeres. Moreover, these events lead to mitotic DNA synthesis (MiDAS) at telomeres mediated by RAD52 through its highly conserved N-terminal domain. We propose that the clustering of large amounts of telomeres in human cancers promotes ALT that is mediated by MiDAS, analogous to Saccharomyces cerevisiae type II ALT survivors.
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Affiliation(s)
- Jaewon Min
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - Woodring E Wright
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - Jerry W Shay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
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38
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Rad52 prevents excessive replication fork reversal and protects from nascent strand degradation. Nat Commun 2019; 10:1412. [PMID: 30926821 PMCID: PMC6441034 DOI: 10.1038/s41467-019-09196-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Accepted: 02/26/2019] [Indexed: 01/02/2023] Open
Abstract
Stabilisation of stalled replication forks prevents excessive fork reversal and their pathological degradation, which can undermine genome integrity. Here we investigate a physiological role of RAD52 at stalled replication forks by using human cell models depleted of RAD52, a specific small-molecule inhibitor of the RAD52-ssDNA interaction, in vitro and single-molecule analyses. We demonstrate that RAD52 prevents excessive degradation of reversed replication forks by MRE11. Mechanistically, RAD52 binds to the stalled replication fork, promotes its occlusion and counteracts loading of SMARCAL1 in vitro and in vivo. Loss of the RAD52 function results in a slightly-defective replication restart, persistence of under-replicated regions and chromosome instability. Moreover, the RAD52-inhibited cells rely on RAD51 for completion of replication and viability upon replication arrest. Collectively, our data suggest an unexpected gatekeeper mechanism by which RAD52 limits excessive remodelling of stalled replication forks, thus indirectly assisting RAD51 and BRCA2 in protecting forks from unscheduled degradation and preventing genome instability. Stabilisation of stalled replication forks prevents excessive fork reversal and genome instability. Here authors reveal a RAD52-dependent replication fork protection mechanism.
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Sherill-Rofe D, Rahat D, Findlay S, Mellul A, Guberman I, Braun M, Bloch I, Lalezari A, Samiei A, Sadreyev R, Goldberg M, Orthwein A, Zick A, Tabach Y. Mapping global and local coevolution across 600 species to identify novel homologous recombination repair genes. Genome Res 2019; 29:439-448. [PMID: 30718334 PMCID: PMC6396423 DOI: 10.1101/gr.241414.118] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 01/22/2019] [Indexed: 12/02/2022]
Abstract
The homologous recombination repair (HRR) pathway repairs DNA double-strand breaks in an error-free manner. Mutations in HRR genes can result in increased mutation rate and genomic rearrangements, and are associated with numerous genetic disorders and cancer. Despite intensive research, the HRR pathway is not yet fully mapped. Phylogenetic profiling analysis, which detects functional linkage between genes using coevolution, is a powerful approach to identify factors in many pathways. Nevertheless, phylogenetic profiling has limited predictive power when analyzing pathways with complex evolutionary dynamics such as the HRR. To map novel HRR genes systematically, we developed clade phylogenetic profiling (CladePP). CladePP detects local coevolution across hundreds of genomes and points to the evolutionary scale (e.g., mammals, vertebrates, animals, plants) at which coevolution occurred. We found that multiscale coevolution analysis is significantly more biologically relevant and sensitive to detect gene function. By using CladePP, we identified dozens of unrecognized genes that coevolved with the HRR pathway, either globally across all eukaryotes or locally in different clades. We validated eight genes in functional biological assays to have a role in DNA repair at both the cellular and organismal levels. These genes are expected to play a role in the HRR pathway and might lead to a better understanding of missing heredity in HRR-associated cancers (e.g., heredity breast and ovarian cancer). Our platform presents an innovative approach to predict gene function, identify novel factors related to different diseases and pathways, and characterize gene evolution.
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Affiliation(s)
- Dana Sherill-Rofe
- Department of Developmental Biology and Cancer Research, Institute for Medical Research-Israel-Canada, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Dolev Rahat
- Department of Developmental Biology and Cancer Research, Institute for Medical Research-Israel-Canada, Hebrew University of Jerusalem, Jerusalem 91120, Israel.,Sharett Institute of Oncology, Hadassah Medical Center, Ein-Kerem, Jerusalem 91120, Israel
| | - Steven Findlay
- Lady Davis Institute for Medical Research, Segal Cancer Centre, Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada.,Division of Experimental Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada
| | - Anna Mellul
- Department of Developmental Biology and Cancer Research, Institute for Medical Research-Israel-Canada, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Irene Guberman
- Department of Developmental Biology and Cancer Research, Institute for Medical Research-Israel-Canada, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Maya Braun
- Department of Developmental Biology and Cancer Research, Institute for Medical Research-Israel-Canada, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Idit Bloch
- Department of Developmental Biology and Cancer Research, Institute for Medical Research-Israel-Canada, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Alon Lalezari
- Department of Developmental Biology and Cancer Research, Institute for Medical Research-Israel-Canada, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Arash Samiei
- Lady Davis Institute for Medical Research, Segal Cancer Centre, Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada.,Division of Experimental Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada
| | - Ruslan Sadreyev
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.,Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA
| | - Michal Goldberg
- Department of Genetics, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Alexandre Orthwein
- Lady Davis Institute for Medical Research, Segal Cancer Centre, Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada.,Division of Experimental Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada.,Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada.,Gerald Bronfman Department of Oncology, McGill University, Montreal, Quebec H4A 3T2, Canada
| | - Aviad Zick
- Sharett Institute of Oncology, Hadassah Medical Center, Ein-Kerem, Jerusalem 91120, Israel
| | - Yuval Tabach
- Department of Developmental Biology and Cancer Research, Institute for Medical Research-Israel-Canada, Hebrew University of Jerusalem, Jerusalem 91120, Israel
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Verma P, Dilley RL, Zhang T, Gyparaki MT, Li Y, Greenberg RA. RAD52 and SLX4 act nonepistatically to ensure telomere stability during alternative telomere lengthening. Genes Dev 2019; 33:221-235. [PMID: 30692206 PMCID: PMC6362809 DOI: 10.1101/gad.319723.118] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 12/05/2018] [Indexed: 11/25/2022]
Abstract
Approximately 15% of cancers use homologous recombination for alternative lengthening of telomeres (ALT). How the initiating genomic lesions invoke homology-directed telomere synthesis remains enigmatic. Here, we show that distinct dependencies exist for telomere synthesis in response to replication stress or DNA double-strand breaks (DSBs). RAD52 deficiency reduced spontaneous telomeric DNA synthesis and replication stress-associated recombination in G2, concomitant with telomere shortening and damage. However, viability and proliferation remained unaffected, suggesting that alternative telomere recombination mechanisms compensate in the absence of RAD52. In agreement, RAD52 was dispensable for DSB-induced telomere synthesis. Moreover, a targeted CRISPR screen revealed that loss of the structure-specific endonuclease scaffold SLX4 reduced the proliferation of RAD52-null ALT cells. While SLX4 was dispensable for RAD52-mediated ALT telomere synthesis in G2, combined SLX4 and RAD52 loss resulted in elevated telomere loss, unresolved telomere recombination intermediates, and mitotic infidelity. These findings establish that RAD52 and SLX4 mediate distinct postreplicative DNA repair processes that maintain ALT telomere stability and cancer cell viability.
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Affiliation(s)
- Priyanka Verma
- Department of Cancer Biology, Basser Center for BRCA, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Robert L Dilley
- Department of Cancer Biology, Basser Center for BRCA, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Tianpeng Zhang
- Department of Cancer Biology, Basser Center for BRCA, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Melina T Gyparaki
- Department of Cancer Biology, Basser Center for BRCA, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Yiwen Li
- Department of Cancer Biology, Basser Center for BRCA, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Roger A Greenberg
- Department of Cancer Biology, Basser Center for BRCA, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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41
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A simple fluorescent assay for the discovery of protein-protein interaction inhibitors. Anal Biochem 2019; 569:46-52. [PMID: 30707898 DOI: 10.1016/j.ab.2019.01.010] [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: 11/16/2018] [Revised: 01/25/2019] [Accepted: 01/28/2019] [Indexed: 12/14/2022]
Abstract
Due to the therapeutic potential of targeting protein-protein interactions (PPIs) there is a need for easily executed assays to perform high throughput screening (HTS) of inhibitors. We have developed and optimized an innovative and robust fluorescence-based assay for detecting PPI inhibitors, called FluorIA (Fluorescence-based protein-protein Interaction Assay). Targeting the PPI of RAD52 with replication protein A (RPA) was used as an example, and the FluorIA protocol design, optimization and successful application to HTS of large chemical libraries are described. Here enhanced green fluorescent protein (EGFP)-tagged RAD52 detected the PPI using full-length RPA heterotrimer coated, black microtiter plates and loss in fluorescence intensity identified small molecule inhibitors (SMIs) that displaced the EGFP-tagged RAD52. The FluorIA design and protocol can be adapted and applied to detect PPIs for other protein systems. This should push forward efforts to develop targeted therapeutics against protein complexes in pathological processes.
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42
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Mahajan S, Raina K, Verma S, Rao BJ. Human RAD52 protein regulates homologous recombination and checkpoint function in BRCA2 deficient cells. Int J Biochem Cell Biol 2018; 107:128-139. [PMID: 30590106 DOI: 10.1016/j.biocel.2018.12.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 12/14/2018] [Accepted: 12/22/2018] [Indexed: 12/16/2022]
Abstract
Cancer cells exhibit HR defects, increased proliferation and checkpoint aberrations. Tumour suppressor proteins, BRCA2 and p53 counteract such aberrant proliferation by checkpoint regulation. Intriguingly, chemo-resistant cancer cells, exhibiting mutated BRCA2 and p53 protein survive even with increased DNA damage accumulation. Such cancer cells show upregulation of RAD52 tumour suppressor protein implying that RAD52 might be providing survival advantage to cancer cells. To understand this paradoxical condition of a tumour suppressor protein facilitating cancer cell survival, in the current study, we investigate the role of RAD52 overexpression in BRCA2 deficient cells. We provide evidence that RAD52 protein alleviates HR inhibition imposed by p53 in BRCA2 deficient cells. In addition, we study the role of RAD52 protein during short replication stress in BRCA2 deficient cells. BRCA2 deficient cells exhibit excessive origin firing and checkpoint evasion in the presence of prevailing DNA damage. Interestingly, overexpression of RAD52 rescues the excessive origin firing and checkpoint defects observed in BRCA2 deficient cells, indicating RAD52 protein compensates for the loss of BRCA2 function. We show that RAD52 protein, just as BRCA2, interacts with pCHK1 checkpoint protein and helps maintain the checkpoint control in BRCA2 deficient cells during DNA damage response.
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Affiliation(s)
- Sukrit Mahajan
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Komal Raina
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Shalini Verma
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - B J Rao
- Indian Institute of Science Education and Research, Tirupati, India.
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43
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Genome Instability Is Promoted by the Chromatin-Binding Protein Spn1 in Saccharomyces cerevisiae. Genetics 2018; 210:1227-1237. [PMID: 30301740 DOI: 10.1534/genetics.118.301600] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 10/02/2018] [Indexed: 02/06/2023] Open
Abstract
Cells expend a large amount of energy to maintain their DNA sequence. DNA repair pathways, cell cycle checkpoint activation, proofreading polymerases, and chromatin structure are ways in which the cell minimizes changes to the genome. During replication, the DNA-damage tolerance pathway allows the replication forks to bypass damage on the template strand. This avoids prolonged replication fork stalling, which can contribute to genome instability. The DNA-damage tolerance pathway includes two subpathways: translesion synthesis and template switch. Post-translational modification of PCNA and the histone tails, cell cycle phase, and local DNA structure have all been shown to influence subpathway choice. Chromatin architecture contributes to maintaining genome stability by providing physical protection of the DNA and by regulating DNA-processing pathways. As such, chromatin-binding factors have been implicated in maintaining genome stability. Using Saccharomyces cerevisiae, we examined the role of Spn1 (Suppresses postrecruitment gene number 1), a chromatin-binding and transcription elongation factor, in DNA-damage tolerance. Expression of a mutant allele of SPN1 results in increased resistance to the DNA-damaging agent methyl methanesulfonate, lower spontaneous and damage-induced mutation rates, along with increased chronological life span. We attribute these effects to an increased usage of the template switch branch of the DNA-damage tolerance pathway in the spn1 strain. This provides evidence for a role of wild-type Spn1 in promoting genome instability, as well as having ties to overcoming replication stress and contributing to chronological aging.
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44
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Human Rad52 Promotes XPG-Mediated R-loop Processing to Initiate Transcription-Associated Homologous Recombination Repair. Cell 2018; 175:558-570.e11. [DOI: 10.1016/j.cell.2018.08.056] [Citation(s) in RCA: 182] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 05/02/2018] [Accepted: 08/22/2018] [Indexed: 12/22/2022]
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45
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Whelan DR, Lee WTC, Yin Y, Ofri DM, Bermudez-Hernandez K, Keegan S, Fenyo D, Rothenberg E. Spatiotemporal dynamics of homologous recombination repair at single collapsed replication forks. Nat Commun 2018; 9:3882. [PMID: 30250272 PMCID: PMC6155164 DOI: 10.1038/s41467-018-06435-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 09/06/2018] [Indexed: 01/07/2023] Open
Abstract
Homologous recombination (HR) is a crucial pathway for the repair of DNA double-strand breaks. BRCA1/2 breast cancer proteins are key players in HR via their mediation of RAD51 nucleofilament formation and function; however, their individual roles and crosstalk in vivo are unknown. Here we use super-resolution (SR) imaging to map the spatiotemporal kinetics of HR proteins, revealing the interdependent relationships that govern the dynamic interplay and progression of repair events. We show that initial single-stranded DNA/RAD51 nucleofilament formation is mediated by RAD52 or, in the absence of RAD52, by BRCA2. In contrast, only BRCA2 can orchestrate later RAD51 recombinase activity during homology search and resolution. Furthermore, we establish that upstream BRCA1 activity is critical for BRCA2 function. Our analyses reveal the underlying epistatic landscape of RAD51 functional dependence on RAD52, BRCA1, and BRCA2 during HR and explain the phenotypic similarity of diseases associated with mutations in these proteins.
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Affiliation(s)
- Donna R Whelan
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA.,Department of Pharmacy and Applied Science, La Trobe Institute for Molecular Science, La Trobe University, Bendigo, VIC, Australia
| | - Wei Ting C Lee
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA
| | - Yandong Yin
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA
| | - Dylan M Ofri
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA
| | - Keria Bermudez-Hernandez
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA
| | - Sarah Keegan
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA
| | - David Fenyo
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA.
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46
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Selinexor reduces the expression of DNA damage repair proteins and sensitizes cancer cells to DNA damaging agents. Oncotarget 2018; 9:30773-30786. [PMID: 30112106 PMCID: PMC6089403 DOI: 10.18632/oncotarget.25637] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 06/01/2018] [Indexed: 12/21/2022] Open
Abstract
Introduction The goal of this study was to examine the effects of selinexor, an inhibitor of exportin-1 mediated nuclear export, on DNA damage repair and to evaluate the cytotoxic effects of selinexor in combination with DNA damaging agents (DDAs) in cancer cells. Results Selinexor reduced the expression of DNA damage repair (DDR) proteins. This did not induce significant DNA damage in tested cell lines. Inhibition of DDR protein expression resulted in enhanced cancer cell death when cells were pretreated with DDAs. In contrast, enhanced cell death was not detected in cells that were pretreated with selinexor then with DDAs. In vivo, single-agent selinexor, docetaxel, or cisplatin treatment resulted in 66.7%, 51.5%, and 26.6% tumor growth inhibition (TGI), respectively, in an MDA-MB-231 xenograft model. Consequently, combination treatment with docetaxel or cisplatin followed by selinexor in vivo resulted in 93.9% and 103.4% TGI, respectively. Immunohistochemical staining and immunoblot analysis of tumor sections confirmed reduced expression of DDR proteins. Conclusion Selinexor treatment inhibited DDR mechanisms in cancer cell lines and therefore potentiated DNA damage-based therapy. The sequential combination of DDAs followed by selinexor increased cancer cell death. This combination is superior to each individual therapy and has a mechanistic rationale as a novel anticancer strategy. Methods Cancer cells treated with selinexor ± DDAs were analyzed using reverse phase protein arrays, immunoblots, quantitative PCR and immunofluorescence. Mice bearing MDA-MB-231 tumors were treated with subtherapeutic doses of selinexor, cisplatin, docetaxel and selinexor in combination with either cisplatin or docetaxel. Tumor growth was evaluated for 25 days.
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Samach A, Gurevich V, Avivi-Ragolsky N, Levy AA. The effects of AtRad52 over-expression on homologous recombination in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 95:30-40. [PMID: 29667244 DOI: 10.1111/tpj.13927] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Revised: 03/20/2018] [Accepted: 03/22/2018] [Indexed: 06/08/2023]
Abstract
AtRad52 homologs are involved in DNA recombination and repair, but their precise functions in different homologous recombination (HR) pathways or in gene-targeting have not been analyzed. In order to facilitate our analyses, we generated an AtRad52-1A variant that had a stronger nuclear localization than the native gene thanks to the removal of the transit peptide for mitochondrial localization and to the addition of a nuclear localization signal. Over-expression of this variant increased HR in the nucleus, compared with the native AtRad52-1A: it increased intra-chromosomal recombination and synthesis-dependent strand-annealing HR repair rates; but conversely, it repressed the single-strand annealing pathway. The effect of AtRad52-1A over-expression on gene-targeting was tested with and without the expression of small RNAs generated from an RNAi construct containing homology to the target and donor sequences. True gene-targeting events at the Arabidopsis Cruciferin locus were obtained only when combining AtRad52-1A over-expression and target/donor-specific RNAi. This suggests that sequence-specific small RNAs might be involved in AtRad52-1A-mediated HR.
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Affiliation(s)
- Aviva Samach
- Department of Plant and Environmental Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Vyacheslav Gurevich
- Department of Plant and Environmental Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Naomi Avivi-Ragolsky
- Department of Plant and Environmental Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Avraham A Levy
- Department of Plant and Environmental Sciences, The Weizmann Institute of Science, Rehovot, Israel
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48
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Structural Basis of Homology-Directed DNA Repair Mediated by RAD52. iScience 2018; 3:50-62. [PMID: 30428330 PMCID: PMC6137706 DOI: 10.1016/j.isci.2018.04.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 03/07/2018] [Accepted: 03/20/2018] [Indexed: 11/21/2022] Open
Abstract
RAD52 mediates homologous recombination by annealing cDNA strands. However, the detailed mechanism of DNA annealing promoted by RAD52 has remained elusive. Here we report two crystal structures of human RAD52 single-stranded DNA (ssDNA) complexes that probably represent key reaction intermediates of RAD52-mediated DNA annealing. The first structure revealed a "wrapped" conformation of ssDNA around the homo-oligomeric RAD52 ring, in which the edges of the bases involved in base pairing are exposed to the solvent. The ssDNA conformation is close to B-form and appears capable of engaging in Watson-Crick base pairing with the cDNA strand. The second structure revealed a "trapped" conformation of ssDNA between two RAD52 rings. This conformation is stabilized by a different RAD52 DNA binding site, which promotes the accumulation of multiple RAD52 rings on ssDNA and the aggregation of ssDNA. These structures provide a structural framework for understanding the mechanism of RAD52-mediated DNA annealing.
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49
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Mendez-Dorantes C, Bhargava R, Stark JM. Repeat-mediated deletions can be induced by a chromosomal break far from a repeat, but multiple pathways suppress such rearrangements. Genes Dev 2018; 32:524-536. [PMID: 29636371 PMCID: PMC5959236 DOI: 10.1101/gad.311084.117] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 03/20/2018] [Indexed: 12/20/2022]
Abstract
Here, Mendez-Dorantes et al. investigated how far a chromosomal double-strand break (DSB) can be positioned from a repeat sequence to induce repeat-mediated rearrangements in mammalian cells. Using a novel reporter assay in mouse embryonic stem cells, they found that a DSB separated from the 3′ repeat by 28.4 kb can still substantially induce RMDs, indicating that a DSB is sufficient to induce RMDs at a relatively far distance. Chromosomal deletion rearrangements mediated by repetitive elements often involve repeats separated by several kilobases and sequences that are divergent. While such rearrangements are likely induced by DNA double-strand breaks (DSBs), it has been unclear how the proximity of DSBs relative to repeat sequences affects the frequency of such events. We generated a reporter assay in mouse cells for a deletion rearrangement involving repeats separated by 0.4 Mb. We induced this repeat-mediated deletion (RMD) rearrangement with two DSBs: the 5′ DSB that is just downstream from the first repeat and the 3′ DSB that is varying distances upstream of the second repeat. Strikingly, we found that increasing the 3′ DSB/repeat distance from 3.3 kb to 28.4 kb causes only a modest decrease in rearrangement frequency. We also found that RMDs are suppressed by KU70 and RAD51 and promoted by RAD52, CtIP, and BRCA1. In addition, we found that 1%–3% sequence divergence substantially suppresses these rearrangements in a manner dependent on the mismatch repair factor MSH2, which is dominant over the suppressive role of KU70. We suggest that a DSB far from a repeat can stimulate repeat-mediated rearrangements, but multiple pathways suppress these events.
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Affiliation(s)
- Carlos Mendez-Dorantes
- Department of Cancer Genetics and Epigenetics, City of Hope, Duarte, California 91010, USA.,Irell and Manella Graduate School of Biological Sciences, City of Hope, Duarte, California 91010, USA
| | - Ragini Bhargava
- Department of Cancer Genetics and Epigenetics, City of Hope, Duarte, California 91010, USA.,Irell and Manella Graduate School of Biological Sciences, City of Hope, Duarte, California 91010, USA
| | - Jeremy M Stark
- Department of Cancer Genetics and Epigenetics, City of Hope, Duarte, California 91010, USA.,Irell and Manella Graduate School of Biological Sciences, City of Hope, Duarte, California 91010, USA
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50
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Sidorova J. A game of substrates: replication fork remodeling and its roles in genome stability and chemo-resistance. Cell Stress 2017; 1:115-133. [PMID: 29355244 PMCID: PMC5771654 DOI: 10.15698/cst2017.12.114] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 11/27/2017] [Accepted: 11/29/2017] [Indexed: 01/06/2023] Open
Abstract
During the hours that human cells spend in the DNA synthesis (S) phase of the cell cycle, they may encounter adversities such as DNA damage or shortage of nucleotides. Under these stresses, replication forks in DNA may experience slowing, stalling, and breakage. Fork remodeling mechanisms, which stabilize slow or stalled replication forks and ensure their ability to continue or resume replication, protect cells from genomic instability and carcinogenesis. Fork remodeling includes DNA strand exchanges that result in annealing of newly synthesized strands (fork reversal), controlled DNA resection, and cleavage of DNA strands. Defects in major tumor suppressor genes BRCA1 and BRCA2, and a subset of the Fanconi Anemia genes have been shown to result in deregulation in fork remodeling, and most prominently, loss of kilobases of nascent DNA from stalled replication forks. This phenomenon has recently gained spotlight as a potential marker and mediator of chemo-sensitivity in cancer cells and, conversely, its suppression - as a hallmark of acquired chemo-resistance. Moreover, nascent strand degradation at forks is now known to also trigger innate immune response to self-DNA. An increasingly sophisticated molecular description of these events now points at a combination of unbalanced fork reversal and end-resection as a root cause, yet also reveals the multi-layered complexity and heterogeneity of the underlying processes in normal and cancer cells.
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Affiliation(s)
- Julia Sidorova
- Department of Pathology, University of Washington, Seattle, Washington, USA
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