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Ngoi NYL, Gallo D, Torrado C, Nardo M, Durocher D, Yap TA. Synthetic lethal strategies for the development of cancer therapeutics. Nat Rev Clin Oncol 2025; 22:46-64. [PMID: 39627502 DOI: 10.1038/s41571-024-00966-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2024] [Indexed: 12/20/2024]
Abstract
Synthetic lethality is a genetic phenomenon whereby the simultaneous presence of two different genetic alterations impairs cellular viability. Importantly, targeting synthetic lethal interactions offers potential therapeutic strategies for cancers with alterations in pathways that might otherwise be considered undruggable. High-throughput screening methods based on modern CRISPR-Cas9 technologies have emerged and become crucial for identifying novel synthetic lethal interactions with the potential for translation into biologically rational cancer therapeutic strategies as well as associated predictive biomarkers of response capable of guiding patient selection. Spurred by the clinical success of PARP inhibitors in patients with BRCA-mutant cancers, novel agents targeting multiple synthetic lethal interactions within DNA damage response pathways are in clinical development, and rational strategies targeting synthetic lethal interactions spanning alterations in epigenetic, metabolic and proliferative pathways have also emerged and are in late preclinical and/or early clinical testing. In this Review, we provide a comprehensive overview of established and emerging technologies for synthetic lethal drug discovery and development and discuss promising therapeutic strategies targeting such interactions.
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Affiliation(s)
- Natalie Y L Ngoi
- Department of Investigational Cancer Therapeutics (Phase I Clinical Trials Program), Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Department of Haematology-Oncology, National University Cancer Institute, Singapore, Singapore
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - David Gallo
- Repare Therapeutics, Inc., Montreal, Quebec, Canada
| | - Carlos Torrado
- Department of Investigational Cancer Therapeutics (Phase I Clinical Trials Program), Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Mirella Nardo
- Department of Investigational Cancer Therapeutics (Phase I Clinical Trials Program), Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Daniel Durocher
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Timothy A Yap
- Department of Investigational Cancer Therapeutics (Phase I Clinical Trials Program), Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
- Therapeutics Discovery Division, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
- Khalifa Institute for Personalized Cancer Therapy, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
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Galli M, Frigerio C, Colombo CV, Casari E, Longhese MP, Clerici M. Exo1 cooperates with Tel1/ATM in promoting recombination events at DNA replication forks. iScience 2024; 27:110410. [PMID: 39081288 PMCID: PMC11284563 DOI: 10.1016/j.isci.2024.110410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 05/27/2024] [Accepted: 06/27/2024] [Indexed: 08/02/2024] Open
Abstract
Tel1/ataxia telangiectasia mutated (ATM) kinase plays multiple functions in response to DNA damage, promoting checkpoint-mediated cell-cycle arrest and repair of broken DNA. In addition, Saccharomyces cerevisiae Tel1 stabilizes replication forks that arrest upon the treatment with the topoisomerase poison camptothecin (CPT). We discover that inactivation of the Exo1 nuclease exacerbates the sensitivity of Tel1-deficient cells to CPT and other agents that hamper DNA replication. Furthermore, cells lacking both Exo1 and Tel1 activities exhibit sustained checkpoint activation in the presence of CPT, indicating that Tel1 and Exo1 limit the activation of a Mec1-dependent checkpoint. The absence of Tel1 or its kinase activity enhances recombination between inverted DNA repeats induced by replication fork blockage in an Exo1-dependent manner. Thus, we propose that Exo1 processes intermediates arising at stalled forks in tel1 mutants to promote DNA replication recovery and cell survival.
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Affiliation(s)
- Michela Galli
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano, Italy
| | - Chiara Frigerio
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano, Italy
| | - Chiara Vittoria Colombo
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano, Italy
| | - Erika Casari
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano, Italy
| | - Michela Clerici
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano, Italy
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Gnugnoli M, Rinaldi C, Casari E, Pizzul P, Bonetti D, Longhese MP. Proteasome-mediated degradation of long-range nucleases negatively regulates resection of DNA double-strand breaks. iScience 2024; 27:110373. [PMID: 39071887 PMCID: PMC11277358 DOI: 10.1016/j.isci.2024.110373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 04/30/2024] [Accepted: 06/21/2024] [Indexed: 07/30/2024] Open
Abstract
Homologous recombination is initiated by the nucleolytic degradation (resection) of DNA double-strand breaks (DSBs). DSB resection is a two-step process. In the short-range step, the MRX (Mre11-Rad50-Xrs2) complex, together with Sae2, incises the 5'-terminated strand at the DSB end and resects back toward the DNA end. Then, the long-range resection nucleases Exo1 and Dna2 further elongate the resected DNA tracts. We found that mutations lowering proteasome functionality bypass the need for Sae2 in DSB resection. In particular, the dysfunction of the proteasome subunit Rpn11 leads to hyper-resection and increases the levels of both Exo1 and Dna2 to such an extent that it allows the bypass of the requirement for either Exo1 or Dna2, but not for both. These observations, along with the finding that Exo1 and Dna2 are ubiquitylated, indicate a role of the proteasome in restraining DSB resection by negatively controlling the abundance of the long-range resection nucleases.
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Affiliation(s)
- Marco Gnugnoli
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Carlo Rinaldi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Erika Casari
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Paolo Pizzul
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Diego Bonetti
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
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4
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Leu YL, Cheng SF, Wang TH, Feng CH, Chen YJ, Hsieh YC, Lan YH, Chen CC. Increasing DNA damage sensitivity through corylin-mediated inhibition of homologous recombination. Biomed Pharmacother 2024; 176:116864. [PMID: 38865847 DOI: 10.1016/j.biopha.2024.116864] [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: 03/24/2024] [Revised: 05/23/2024] [Accepted: 06/03/2024] [Indexed: 06/14/2024] Open
Abstract
BACKGROUND DNA repair allows the survival of cancer cells. Therefore, the development of DNA repair inhibitors is a critical need for sensitizing cancers to chemoradiation. Sae2CtIP has specific functions in initiating DNA end resection, as well as coordinating cell cycle checkpoints, and it also greatly interacts with the DDR at different levels. RESULTS In this study, we demonstrated that corylin, a potential sensitizer, causes deficiencies in DNA repair and DNA damage checkpoints in yeast cells. More specifically, corylin increases DNA damage sensitivity through the Sae2-dependent pathway and impairs the activation of Mec1-Ddc2, Rad53-p and γ-H2A. In breast cancer cells, corylin increases apoptosis and reduces proliferation following Dox treatment by inhibiting CtIP. Xenograft assays showed that treatment with corylin combined with Dox significantly reduced tumor growth in vivo. CONCLUSIONS Our findings herein delineate the mechanisms of action of corylin in regulating DNA repair and indicate that corylin has potential long-term clinical utility as a DDR inhibitor.
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Affiliation(s)
- Yann-Lii Leu
- Graduate Institute of Natural products, College of Medicine, No.259, Wenhua 1st Rd., Guishan Dist., Taoyuan City 33302, Taiwan, ROC; Biobank, Chang Gung Memorial Hospital, No. 5, Fuxing St., Guishan Dist., Taoyuan City 33305, Taiwan, ROC
| | - Shu-Fang Cheng
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, No.259, Wenhua 1st Rd., Guishan Dist., Taoyuan City, Taiwan, ROC; Graduate Institute of Natural products, College of Medicine, No.259, Wenhua 1st Rd., Guishan Dist., Taoyuan City 33302, Taiwan, ROC
| | - Tong-Hong Wang
- Biobank, Chang Gung Memorial Hospital, No. 5, Fuxing St., Guishan Dist., Taoyuan City 33305, Taiwan, ROC
| | - Chun-Hao Feng
- Graduate Institute of Natural products, College of Medicine, No.259, Wenhua 1st Rd., Guishan Dist., Taoyuan City 33302, Taiwan, ROC
| | - Yu-Ju Chen
- Graduate Institute of Natural products, College of Medicine, No.259, Wenhua 1st Rd., Guishan Dist., Taoyuan City 33302, Taiwan, ROC
| | - Yi-Cheng Hsieh
- Office of the Texas State Chemist, Texas A&M AgriLife Research, Texas A&M University System, College Station, TX 77843, USA
| | - Yu-Hsuan Lan
- Department of Pharmacy, College of Pharmacy, China Medical University, No.100, Section 1, Jingmao Rd., Beitun Dist., Taichung City 406040, Taiwan, ROC.
| | - Chin-Chuan Chen
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, No.259, Wenhua 1st Rd., Guishan Dist., Taoyuan City, Taiwan, ROC; Graduate Institute of Natural products, College of Medicine, No.259, Wenhua 1st Rd., Guishan Dist., Taoyuan City 33302, Taiwan, ROC; Healthy Aging Research Center, Chang Gung University, No.259, Wenhua 1st Rd., Guishan Dist., Taoyuan City 33302, Taiwan, ROC; Molecular Medicine Research Center, Chang Gung University, No.259, Wenhua 1st Rd., Guishan Dist., Taoyuan City 33302, Taiwan, ROC; Biobank, Chang Gung Memorial Hospital, No. 5, Fuxing St., Guishan Dist., Taoyuan City 33305, Taiwan, ROC.
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5
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Rinaldi C, Pizzul P, Casari E, Mangiagalli M, Tisi R, Longhese MP. The Ku complex promotes DNA end-bridging and this function is antagonized by Tel1/ATM kinase. Nucleic Acids Res 2023; 51:1783-1802. [PMID: 36762474 PMCID: PMC9976877 DOI: 10.1093/nar/gkad062] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 01/18/2023] [Accepted: 01/20/2023] [Indexed: 02/11/2023] Open
Abstract
DNA double-strand breaks (DSBs) can be repaired by either homologous recombination (HR) or non-homologous end-joining (NHEJ). NHEJ is induced by the binding to DSBs of the Ku70-Ku80 heterodimer, which acts as a hub for the recruitment of downstream NHEJ components. An important issue in DSB repair is the maintenance of the DSB ends in close proximity, a function that in yeast involves the MRX complex and Sae2. Here, we provide evidence that Ku contributes to keep the DNA ends tethered to each other. The ku70-C85Y mutation, which increases Ku affinity for DNA and its persistence very close to the DSB ends, enhances DSB end-tethering and suppresses the end-tethering defect of sae2Δ cells. Impairing histone removal around DSBs either by eliminating Tel1 kinase activity or nucleosome remodelers enhances Ku persistence at DSBs and DSB bridging, suggesting that Tel1 antagonizes the Ku function in supporting end-tethering by promoting nucleosome removal and possibly Ku sliding inwards. As Ku provides a block to DSB resection, this Tel1 function can be important to regulate the mode by which DSBs are repaired.
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Affiliation(s)
- Carlo Rinaldi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Paolo Pizzul
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Erika Casari
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Marco Mangiagalli
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Renata Tisi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
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Interplay between Sae2 and Rif2 in the regulation of Mre11-Rad50 activities at DNA ends. Curr Opin Genet Dev 2021; 71:72-77. [PMID: 34311383 DOI: 10.1016/j.gde.2021.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/01/2021] [Indexed: 02/06/2023]
Abstract
DNA double-strand breaks (DSBs) can be repaired by non-homologous end-joining (NHEJ) or homologous recombination (HR). HR is initiated by nucleolytic degradation of the DSB ends in a process termed resection. The Mre11-Rad50-Xrs2/NBS1 (MRX/N) complex is a multifunctional enzyme that, aided by the Sae2/CtIP protein, promotes DSB resection and maintains the DSB ends tethered to each other to facilitate their re-ligation. Furthermore, it activates the protein kinase Tel1/ATM, which initiates DSB signaling. In Saccharomyces cerevisiae, these MRX functions are inhibited by the Rif2 protein, which is enriched at telomeres and protects telomeric DNA from being sensed and processed as a DSB. The present review focuses on recent data showing that Sae2 and Rif2 regulate MRX functions in opposite manners by interacting with Rad50 and influencing ATP-dependent Mre11-Rad50 conformational changes. As Sae2 is enriched at DSBs whereas Rif2 is predominantly present at telomeres, the relative abundance of these two MRX regulators can provide an effective mechanism to activate or inactivate MRX depending on the nature of chromosome ends.
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7
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Marsella A, Gobbini E, Cassani C, Tisi R, Cannavo E, Reginato G, Cejka P, Longhese MP. Sae2 and Rif2 regulate MRX endonuclease activity at DNA double-strand breaks in opposite manners. Cell Rep 2021; 34:108906. [PMID: 33789097 PMCID: PMC8028314 DOI: 10.1016/j.celrep.2021.108906] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/29/2021] [Accepted: 03/04/2021] [Indexed: 11/17/2022] Open
Abstract
The Mre11-Rad50-Xrs2 (MRX) complex detects and processes DNA double-strand breaks (DSBs). Its DNA binding and processing activities are regulated by transitions between an ATP-bound state and a post-hydrolysis cutting state that is nucleolytically active. Mre11 endonuclease activity is stimulated by Sae2, whose lack increases MRX persistence at DSBs and checkpoint activation. Here we show that the Rif2 protein inhibits Mre11 endonuclease activity and is responsible for the increased MRX retention at DSBs in sae2Δ cells. We identify a Rad50 residue that is important for Rad50-Rif2 interaction and Rif2 inhibition of Mre11 nuclease. This residue is located near a Rad50 surface that binds Sae2 and is important in stabilizing the Mre11-Rad50 (MR) interaction in the cutting state. We propose that Sae2 stimulates Mre11 endonuclease activity by stabilizing a post-hydrolysis MR conformation that is competent for DNA cleavage, whereas Rif2 antagonizes this Sae2 function and stabilizes an endonuclease inactive MR conformation. Sae2 stimulates Mre11 endonuclease activity by stabilizing the MRX cutting state Rif2 inhibits Sae2-mediated stimulation of Mre11 endonuclease activity The rad50-N18S mutation escapes Rif2-mediated inhibition of Mre11 nuclease Rif2 stabilizes an endonuclease inactive MR conformation that persistently binds DSBs
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Affiliation(s)
- Antonio Marsella
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano 20126, Italy
| | - Elisa Gobbini
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano 20126, Italy
| | - Corinne Cassani
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano 20126, Italy
| | - Renata Tisi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano 20126, Italy
| | - Elda Cannavo
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona, Switzerland
| | - Giordano Reginato
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Petr Cejka
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano 20126, Italy.
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Reginato G, Cejka P. The MRE11 complex: A versatile toolkit for the repair of broken DNA. DNA Repair (Amst) 2020; 91-92:102869. [PMID: 32480356 DOI: 10.1016/j.dnarep.2020.102869] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/30/2020] [Accepted: 05/04/2020] [Indexed: 12/13/2022]
Abstract
When DNA breaks, the ends need to be stabilized and processed to facilitate subsequent repair, which can occur by either direct but error-prone end-joining with another broken DNA molecule or a more accurate homology-directed repair by the recombination machinery. At the same time, the presence of broken DNA triggers a signaling cascade that regulates the repair events and cellular progression through the cell cycle. The MRE11 nuclease, together with RAD50 and NBS1 forms a complex termed MRN that participates in all these processes. Although MRE11 was first identified more than 20 years ago, deep insights into its mechanism of action and regulation are much more recent. Here we review how MRE11 functions within MRN, and how the complex is further regulated by CtIP and its phosphorylation in a cell cycle dependent manner. We describe how RAD50, NBS1 and CtIP convert MRE11, exhibiting per se a 3'→5' exonuclease activity, into an ensemble that instead degrades primarily the 5'-terminated strand by endonucleolytic cleavage at DNA break sites to generate 3' overhangs, as required for the initiation of homologous recombination. The unique mechanism of DNA end resection by MRN-CtIP makes it a very flexible toolkit to process DNA breaks with a variety of secondary structures and protein blocks. Such a block can also be the Ku heterodimer, and emerging evidence suggests that MRN-CtIP may often need to remove Ku from DNA ends before initiating homologous recombination. Misregulation of DNA break repair results in mutations and chromosome rearrangements that can drive cancer development. Therefore, a detailed understanding of the underlying processes is highly relevant for human health.
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Affiliation(s)
- Giordano Reginato
- Institute for Research in Biomedicine, Università della Svizzera Italiana (USI), Faculty of Biomedical Sciences, Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera Italiana (USI), Faculty of Biomedical Sciences, Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland.
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9
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Cassani C, Gobbini E, Vertemara J, Wang W, Marsella A, Sung P, Tisi R, Zampella G, Longhese MP. Structurally distinct Mre11 domains mediate MRX functions in resection, end-tethering and DNA damage resistance. Nucleic Acids Res 2019; 46:2990-3008. [PMID: 29420790 PMCID: PMC5888019 DOI: 10.1093/nar/gky086] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 01/31/2018] [Indexed: 11/27/2022] Open
Abstract
Sae2 cooperates with the Mre11–Rad50-Xrs2 (MRX) complex to initiate resection of DNA double-strand breaks (DSBs) and to maintain the DSB ends in close proximity to allow their repair. How these diverse MRX-Sae2 functions contribute to DNA damage resistance is not known. Here, we describe mre11 alleles that suppress the hypersensitivity of sae2Δ cells to genotoxic agents. By assessing the impact of these mutations at the cellular and structural levels, we found that all the mre11 alleles that restore sae2Δ resistance to both camptothecin and phleomycin affect the Mre11 N-terminus and suppress the resection defect of sae2Δ cells by lowering MRX and Tel1 association to DSBs. As a consequence, the diminished Tel1 persistence potentiates Sgs1-Dna2 resection activity by decreasing Rad9 association to DSBs. By contrast, the mre11 mutations restoring sae2Δ resistance only to phleomycin are located in Mre11 C-terminus and bypass Sae2 function in end-tethering but not in DSB resection, possibly by destabilizing the Mre11–Rad50 open conformation. These findings unmask the existence of structurally distinct Mre11 domains that support resistance to genotoxic agents by mediating different processes.
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Affiliation(s)
- Corinne Cassani
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Elisa Gobbini
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Jacopo Vertemara
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Weibin Wang
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Antonio Marsella
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Renata Tisi
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Giuseppe Zampella
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
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10
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Saatchi F, Kirchmaier AL. Tolerance of DNA Replication Stress Is Promoted by Fumarate Through Modulation of Histone Demethylation and Enhancement of Replicative Intermediate Processing in Saccharomyces cerevisiae. Genetics 2019; 212:631-654. [PMID: 31123043 PMCID: PMC6614904 DOI: 10.1534/genetics.119.302238] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 05/07/2019] [Indexed: 12/28/2022] Open
Abstract
Fumarase is a well-characterized TCA cycle enzyme that catalyzes the reversible conversion of fumarate to malate. In mammals, fumarase acts as a tumor suppressor, and loss-of-function mutations in the FH gene in hereditary leiomyomatosis and renal cell cancer result in the accumulation of intracellular fumarate-an inhibitor of α-ketoglutarate-dependent dioxygenases. Fumarase promotes DNA repair by nonhomologous end joining in mammalian cells through interaction with the histone variant H2A.Z, and inhibition of KDM2B, a H3 K36-specific histone demethylase. Here, we report that Saccharomyces cerevisiae fumarase, Fum1p, acts as a response factor during DNA replication stress, and fumarate enhances survival of yeast lacking Htz1p (H2A.Z in mammals). We observed that exposure to DNA replication stress led to upregulation as well as nuclear enrichment of Fum1p, and raising levels of fumarate in cells via deletion of FUM1 or addition of exogenous fumarate suppressed the sensitivity to DNA replication stress of htz1Δ mutants. This suppression was independent of modulating nucleotide pool levels. Rather, our results are consistent with fumarate conferring resistance to DNA replication stress in htz1Δ mutants by inhibiting the H3 K4-specific histone demethylase Jhd2p, and increasing H3 K4 methylation. Although the timing of checkpoint activation and deactivation remained largely unaffected by fumarate, sensors and mediators of the DNA replication checkpoint were required for fumarate-dependent resistance to replication stress in the htz1Δ mutants. Together, our findings imply metabolic enzymes and metabolites aid in processing replicative intermediates by affecting chromatin modification states, thereby promoting genome integrity.
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Affiliation(s)
- Faeze Saatchi
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
- Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907
- Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907
| | - Ann L Kirchmaier
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
- Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907
- Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907
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11
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Casari E, Rinaldi C, Marsella A, Gnugnoli M, Colombo CV, Bonetti D, Longhese MP. Processing of DNA Double-Strand Breaks by the MRX Complex in a Chromatin Context. Front Mol Biosci 2019; 6:43. [PMID: 31231660 PMCID: PMC6567933 DOI: 10.3389/fmolb.2019.00043] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 05/21/2019] [Indexed: 12/24/2022] Open
Abstract
DNA double-strand breaks (DSBs) are highly cytotoxic lesions that must be repaired to ensure genomic stability and avoid cell death. The cellular response to DSBs is initiated by the evolutionarily conserved Mre11-Rad50-Xrs2/NBS1 (MRX/MRN) complex that has structural and catalytic functions. Furthermore, it is responsible for DSB signaling through the activation of the checkpoint kinase Tel1/ATM. Here, we review functions and regulation of the MRX/MRN complex in DSB processing in a chromatin context, as well as its interplay with Tel1/ATM.
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Affiliation(s)
| | | | | | | | | | | | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
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12
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Uncoupling Sae2 Functions in Downregulation of Tel1 and Rad53 Signaling Activities. Genetics 2018; 211:515-530. [PMID: 30538107 DOI: 10.1534/genetics.118.301830] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 12/09/2018] [Indexed: 11/18/2022] Open
Abstract
The Mre11-Rad50-Xrs2 (MRX) complex acts together with the Sae2 protein to initiate resection of DNA double-strand breaks (DSBs) and to regulate a checkpoint response that couples cell cycle progression with DSB repair. Sae2 supports resistance to DNA damage and downregulates the signaling activities of MRX, Tel1, and Rad53 checkpoint proteins at the sites of damage. How these functions are connected to each other is not known. Here, we describe the separation-of-function sae2-ms mutant that, similar to SAE2 deletion, upregulates MRX and Tel1 signaling activities at DSBs by reducing Mre11 endonuclease activity. However, unlike SAE2 deletion, Sae2-ms causes neither DNA damage sensitivity nor enhanced Rad53 activation, indicating that DNA damage resistance depends mainly on Sae2-mediated Rad53 inhibition. The lack of Sae2, but not the presence of Sae2-ms, impairs long-range resection and increases both Rad9 accumulation at DSBs and Rad53-Rad9 interaction independently of Mre11 nuclease activity. Altogether, these data lead to a model whereby Sae2 plays distinct functions in limiting MRX-Tel1 and Rad9 abundance at DSBs, with the control on Rad9 association playing the major role in supporting DNA damage resistance and in regulating long-range resection and checkpoint activation.
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13
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Sae2 antagonizes Rad9 accumulation at DNA double-strand breaks to attenuate checkpoint signaling and facilitate end resection. Proc Natl Acad Sci U S A 2018; 115:E11961-E11969. [PMID: 30510002 DOI: 10.1073/pnas.1816539115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The Mre11-Rad50-Xrs2NBS1 complex plays important roles in the DNA damage response by activating the Tel1ATM kinase and catalyzing 5'-3' resection at DNA double-strand breaks (DSBs). To initiate resection, Mre11 endonuclease nicks the 5' strands at DSB ends in a reaction stimulated by Sae2CtIP Accordingly, Mre11-nuclease deficient (mre11-nd) and sae2Δ mutants are expected to exhibit similar phenotypes; however, we found several notable differences. First, sae2Δ cells exhibit greater sensitivity to genotoxins than mre11-nd cells. Second, sae2Δ is synthetic lethal with sgs1Δ, whereas the mre11-nd sgs1Δ mutant is viable. Third, Sae2 attenuates the Tel1-Rad53CHK2 checkpoint and antagonizes Rad953BP1 accumulation at DSBs independent of Mre11 nuclease. We show that Sae2 competes with other Tel1 substrates, thus reducing Rad9 binding to chromatin and to Rad53. We suggest that persistent Sae2 binding at DSBs in the mre11-nd mutant counteracts the inhibitory effects of Rad9 and Rad53 on Exo1 and Dna2-Sgs1-mediated resection, accounting for the different phenotypes conferred by mre11-nd and sae2Δ mutations. Collectively, these data show a resection initiation independent role for Sae2 at DSBs by modulating the DNA damage checkpoint.
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14
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Oh J, Symington LS. Role of the Mre11 Complex in Preserving Genome Integrity. Genes (Basel) 2018; 9:E589. [PMID: 30501098 PMCID: PMC6315862 DOI: 10.3390/genes9120589] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 11/26/2018] [Accepted: 11/27/2018] [Indexed: 12/12/2022] Open
Abstract
DNA double-strand breaks (DSBs) are hazardous lesions that threaten genome integrity and cell survival. The DNA damage response (DDR) safeguards the genome by sensing DSBs, halting cell cycle progression and promoting repair through either non-homologous end joining (NHEJ) or homologous recombination (HR). The Mre11-Rad50-Xrs2/Nbs1 (MRX/N) complex is central to the DDR through its structural, enzymatic, and signaling roles. The complex tethers DNA ends, activates the Tel1/ATM kinase, resolves protein-bound or hairpin-capped DNA ends, and maintains telomere homeostasis. In addition to its role at DSBs, MRX/N associates with unperturbed replication forks, as well as stalled replication forks, to ensure complete DNA synthesis and to prevent chromosome rearrangements. Here, we summarize the significant progress made in characterizing the MRX/N complex and its various activities in chromosome metabolism.
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Affiliation(s)
- Julyun Oh
- Biological Sciences Program, Columbia University, New York, NY 10027, USA.
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.
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15
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Regulatory control of DNA end resection by Sae2 phosphorylation. Nat Commun 2018; 9:4016. [PMID: 30275497 PMCID: PMC6167383 DOI: 10.1038/s41467-018-06417-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 08/29/2018] [Indexed: 12/31/2022] Open
Abstract
DNA end resection plays a critical function in DNA double-strand break repair pathway choice. Resected DNA ends are refractory to end-joining mechanisms and are instead channeled to homology-directed repair. Using biochemical, genetic, and imaging methods, we show that phosphorylation of Saccharomyces cerevisiae Sae2 controls its capacity to promote the Mre11-Rad50-Xrs2 (MRX) nuclease to initiate resection of blocked DNA ends by at least two distinct mechanisms. First, DNA damage and cell cycle-dependent phosphorylation leads to Sae2 tetramerization. Second, and independently, phosphorylation of the conserved C-terminal domain of Sae2 is a prerequisite for its physical interaction with Rad50, which is also crucial to promote the MRX endonuclease. The lack of this interaction explains the phenotype of rad50S mutants defective in the processing of Spo11-bound DNA ends during meiotic recombination. Our results define how phosphorylation controls the initiation of DNA end resection and therefore the choice between the key DNA double-strand break repair mechanisms. It has previously been established that DNA end resection in yeast and in humans is under CDK control. Here the authors explain how phosphorylation regulates the capacity of Sae2 — the yeast orthologue of human CtIP — to promote DNA end resection.
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16
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Bonetti D, Colombo CV, Clerici M, Longhese MP. Processing of DNA Ends in the Maintenance of Genome Stability. Front Genet 2018; 9:390. [PMID: 30258457 PMCID: PMC6143663 DOI: 10.3389/fgene.2018.00390] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 08/29/2018] [Indexed: 12/17/2022] Open
Abstract
DNA double-strand breaks (DSBs) are particularly hazardous lesions as their inappropriate repair can result in chromosome rearrangements, an important driving force of tumorigenesis. DSBs can be repaired by end joining mechanisms or by homologous recombination (HR). HR requires the action of several nucleases that preferentially remove the 5′-terminated strands at both DSB ends in a process called DNA end resection. The same nucleases are also involved in the processing of replication fork structures. Much of our understanding of these pathways has come from studies in the model organism Saccharomyces cerevisiae. Here, we review the current knowledge of the mechanism of resection at DNA DSBs and replication forks.
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Affiliation(s)
- Diego Bonetti
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
| | | | - Michela Clerici
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
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17
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Paull TT. 20 Years of Mre11 Biology: No End in Sight. Mol Cell 2018; 71:419-427. [PMID: 30057197 DOI: 10.1016/j.molcel.2018.06.033] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/18/2018] [Accepted: 06/21/2018] [Indexed: 01/01/2023]
Abstract
The Mre11 nuclease has been the subject of intensive investigation for the past 20 years because of the central role that Mre11/Rad50 complexes play in genome maintenance. The last two decades of work on this complex has led to a much deeper understanding of the structure, biochemical activities, and regulation of Mre11/Rad50 complexes from archaea, bacteria, and eukaryotic cells. This review will discuss some of the important findings over recent years that have illuminated roles for the Mre11 nuclease in these different contexts as well as the insights from structural biology that have helped us to understand its mechanisms of action.
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Affiliation(s)
- Tanya T Paull
- Howard Hughes Medical Institute; Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA.
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18
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Menin L, Ursich S, Trovesi C, Zellweger R, Lopes M, Longhese MP, Clerici M. Tel1/ATM prevents degradation of replication forks that reverse after topoisomerase poisoning. EMBO Rep 2018; 19:e45535. [PMID: 29739811 PMCID: PMC6030699 DOI: 10.15252/embr.201745535] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 04/12/2018] [Accepted: 04/19/2018] [Indexed: 01/01/2023] Open
Abstract
In both yeast and mammals, the topoisomerase poison camptothecin (CPT) induces fork reversal, which has been proposed to stabilize replication forks, thus providing time for the repair of CPT-induced lesions and supporting replication restart. We show that Tel1, the Saccharomyces cerevisiae orthologue of human ATM kinase, stabilizes CPT-induced reversed forks by counteracting their nucleolytic degradation by the MRX complex. Tel1-lacking cells are hypersensitive to CPT specifically and show less reversed forks in the presence of CPT The lack of Mre11 nuclease activity restores wild-type levels of reversed forks in CPT-treated tel1Δ cells without affecting fork reversal in wild-type cells. Moreover, Mrc1 inactivation prevents fork reversal in wild-type, tel1Δ, and mre11 nuclease-deficient cells and relieves the hypersensitivity of tel1Δ cells to CPT Altogether, our data indicate that Tel1 counteracts Mre11 nucleolytic activity at replication forks that undergo Mrc1-mediated reversal in the presence of CPT.
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Affiliation(s)
- Luca Menin
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Sebastian Ursich
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Camilla Trovesi
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Ralph Zellweger
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Massimo Lopes
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Michela Clerici
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
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19
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Syed A, Tainer JA. The MRE11-RAD50-NBS1 Complex Conducts the Orchestration of Damage Signaling and Outcomes to Stress in DNA Replication and Repair. Annu Rev Biochem 2018; 87:263-294. [PMID: 29709199 PMCID: PMC6076887 DOI: 10.1146/annurev-biochem-062917-012415] [Citation(s) in RCA: 287] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Genomic instability in disease and its fidelity in health depend on the DNA damage response (DDR), regulated in part from the complex of meiotic recombination 11 homolog 1 (MRE11), ATP-binding cassette-ATPase (RAD50), and phosphopeptide-binding Nijmegen breakage syndrome protein 1 (NBS1). The MRE11-RAD50-NBS1 (MRN) complex forms a multifunctional DDR machine. Within its network assemblies, MRN is the core conductor for the initial and sustained responses to DNA double-strand breaks, stalled replication forks, dysfunctional telomeres, and viral DNA infection. MRN can interfere with cancer therapy and is an attractive target for precision medicine. Its conformations change the paradigm whereby kinases initiate damage sensing. Delineated results reveal kinase activation, posttranslational targeting, functional scaffolding, conformations storing binding energy and enabling access, interactions with hub proteins such as replication protein A (RPA), and distinct networks at DNA breaks and forks. MRN biochemistry provides prototypic insights into how it initiates, implements, and regulates multifunctional responses to genomic stress.
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Affiliation(s)
- Aleem Syed
- Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA; ,
| | - John A Tainer
- Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA; ,
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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20
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Marsella A, Cassani C, Casari E, Tisi R, Longhese MP. Structure–function relationships of the Mre11 protein in the control of DNA end bridging and processing. Curr Genet 2018; 65:11-16. [PMID: 29922906 DOI: 10.1007/s00294-018-0861-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 06/15/2018] [Accepted: 06/15/2018] [Indexed: 12/18/2022]
Affiliation(s)
- Antonio Marsella
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
| | - Corinne Cassani
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
| | - Erika Casari
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
| | - Renata Tisi
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy.
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy.
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21
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Gobbini E, Cassani C, Vertemara J, Wang W, Mambretti F, Casari E, Sung P, Tisi R, Zampella G, Longhese MP. The MRX complex regulates Exo1 resection activity by altering DNA end structure. EMBO J 2018; 37:embj.201798588. [PMID: 29925516 DOI: 10.15252/embj.201798588] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 05/24/2018] [Accepted: 05/30/2018] [Indexed: 01/19/2023] Open
Abstract
Homologous recombination is triggered by nucleolytic degradation (resection) of DNA double-strand breaks (DSBs). DSB resection requires the Mre11-Rad50-Xrs2 (MRX) complex, which promotes the activity of Exo1 nuclease through a poorly understood mechanism. Here, we describe the Mre11-R10T mutant variant that accelerates DSB resection compared to wild-type Mre11 by potentiating Exo1-mediated processing. This increased Exo1 resection activity leads to a decreased association of the Ku complex to DSBs and an enhanced DSB resection in G1, indicating that Exo1 has a direct function in preventing Ku association with DSBs. Molecular dynamics simulations show that rotation of the Mre11 capping domains is able to induce unwinding of double-strand DNA (dsDNA). The R10T substitution causes altered orientation of the Mre11 capping domain that leads to persistent melting of the dsDNA end. We propose that MRX creates a specific DNA end structure that promotes Exo1 resection activity by facilitating the persistence of this nuclease on the DSB ends, uncovering a novel MRX function in DSB resection.
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Affiliation(s)
- Elisa Gobbini
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
| | - Corinne Cassani
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
| | - Jacopo Vertemara
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
| | - Weibin Wang
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT, USA
| | - Fabiana Mambretti
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
| | - Erika Casari
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT, USA
| | - Renata Tisi
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
| | - Giuseppe Zampella
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
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22
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Daley JM, Jimenez-Sainz J, Wang W, Miller AS, Xue X, Nguyen KA, Jensen RB, Sung P. Enhancement of BLM-DNA2-Mediated Long-Range DNA End Resection by CtIP. Cell Rep 2018; 21:324-332. [PMID: 29020620 DOI: 10.1016/j.celrep.2017.09.048] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 07/18/2017] [Accepted: 09/14/2017] [Indexed: 01/24/2023] Open
Abstract
DNA double-strand break repair by homologous recombination entails the resection of DNA ends to reveal ssDNA tails, which are used to invade a homologous DNA template. CtIP and its yeast ortholog Sae2 regulate the nuclease activity of MRE11 in the initial stage of resection. Deletion of CtIP in the mouse or SAE2 in yeast engenders a more severe phenotype than MRE11 nuclease inactivation, indicative of a broader role of CtIP/Sae2. Here, we provide biochemical evidence that CtIP promotes long-range resection via the BLM-DNA2 pathway. Specifically, CtIP interacts with BLM and enhances its helicase activity, and it enhances DNA cleavage by DNA2. Thus, CtIP influences multiple aspects of end resection beyond MRE11 regulation.
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Affiliation(s)
- James M Daley
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA.
| | - Judit Jimenez-Sainz
- Department of Therapeutic Radiobiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Weibin Wang
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Adam S Miller
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Xiaoyu Xue
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Kevin A Nguyen
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Ryan B Jensen
- Department of Therapeutic Radiobiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA.
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23
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Herzog M, Puddu F, Coates J, Geisler N, Forment JV, Jackson SP. Detection of functional protein domains by unbiased genome-wide forward genetic screening. Sci Rep 2018; 8:6161. [PMID: 29670134 PMCID: PMC5906580 DOI: 10.1038/s41598-018-24400-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 03/22/2018] [Indexed: 12/21/2022] Open
Abstract
Establishing genetic and chemo-genetic interactions has played key roles in elucidating mechanisms by which certain chemicals perturb cellular functions. In contrast to gene disruption/depletion strategies to identify mechanisms of drug resistance, searching for point-mutational genetic suppressors that can identify separation- or gain-of-function mutations has been limited. Here, by demonstrating its utility in identifying chemical-genetic suppressors of sensitivity to the DNA topoisomerase I poison camptothecin or the poly(ADP-ribose) polymerase inhibitor olaparib, we detail an approach allowing systematic, large-scale detection of spontaneous or chemically-induced suppressor mutations in yeast or haploid mammalian cells in a short timeframe, and with potential applications in other haploid systems. In addition to applications in molecular biology research, this protocol can be used to identify drug targets and predict drug-resistance mechanisms. Mapping suppressor mutations on the primary or tertiary structures of protein suppressor hits provides insights into functionally relevant protein domains. Importantly, we show that olaparib resistance is linked to missense mutations in the DNA binding regions of PARP1, but not in its catalytic domain. This provides experimental support to the concept of PARP1 trapping on DNA as the prime source of toxicity to PARP inhibitors, and points to a novel olaparib resistance mechanism with potential therapeutic implications.
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Affiliation(s)
- Mareike Herzog
- The Wellcome/CRUK Gurdon Institute and Department of Biochemistry, University of Cambridge, Tennis Court Road, CB2 1QN, Cambridge, UK
| | - Fabio Puddu
- The Wellcome/CRUK Gurdon Institute and Department of Biochemistry, University of Cambridge, Tennis Court Road, CB2 1QN, Cambridge, UK
| | - Julia Coates
- The Wellcome/CRUK Gurdon Institute and Department of Biochemistry, University of Cambridge, Tennis Court Road, CB2 1QN, Cambridge, UK
| | - Nicola Geisler
- The Wellcome/CRUK Gurdon Institute and Department of Biochemistry, University of Cambridge, Tennis Court Road, CB2 1QN, Cambridge, UK
| | - Josep V Forment
- The Wellcome/CRUK Gurdon Institute and Department of Biochemistry, University of Cambridge, Tennis Court Road, CB2 1QN, Cambridge, UK.
- AstraZeneca, Oncology DNA damage response group, Hodgkin Building, 310 Cambridge Science Park, Milton Road, CB4 0WG, Cambridge, UK.
| | - Stephen P Jackson
- The Wellcome/CRUK Gurdon Institute and Department of Biochemistry, University of Cambridge, Tennis Court Road, CB2 1QN, Cambridge, UK.
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24
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Teye EK, Sido A, Xin P, Finnberg NK, Gokare P, Kawasawa YI, Salzberg AC, Shimko S, Bayerl M, Ehmann WC, Claxton DF, Rybka WB, Drabick JJ, Wang HG, Abraham T, El-Deiry WS, Brodsky RA, J Hohl R, Pu JJ. PIGN gene expression aberration is associated with genomic instability and leukemic progression in acute myeloid leukemia with myelodysplastic features. Oncotarget 2018; 8:29887-29905. [PMID: 28187452 PMCID: PMC5444711 DOI: 10.18632/oncotarget.15136] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 01/11/2017] [Indexed: 11/26/2022] Open
Abstract
Previous studies have linked increased frequency of glycosylphosphatidylinositol-anchor protein (GPI-AP) deficiency with genomic instability and the risk of carcinogenesis. However, the underlying mechanism is still not clear. A randomForest analysis of the gene expression array data from 55 MDS patients (GSE4619) demonstrated a significant (p = 0.0007) correlation (Pearson r =-0.4068) between GPI-anchor biosynthesis gene expression and genomic instability, in which PIGN, a gene participating in GPI-AP biosynthesis, was ranked as the third most important in predicting risk of MDS progression. Furthermore, we observed that PIGN gene expression aberrations (increased transcriptional activity but diminished to no protein production) were associated with increased frequency of GPI-AP deficiency in leukemic cells during leukemic transformation/progression. PIGN gene expression aberrations were attributed to partial intron retentions between exons 14 and 15 resulting in frameshifts and premature termination which were confirmed by examining the RNA-seq data from a group of AML patients (phs001027.v1.p1). PIGN gene expression aberration correlated with the elevation of genomic instability marker expression that was independent of the TP53 regulatory pathway. Suppression/elimination of PIGN protein expression caused a similar pattern of genomic instability that was rescued by PIGN restoration. Finally, we found that PIGN bound to the spindle assembly checkpoint protein, MAD1, and regulated its expression during the cell cycle. In conclusion, PIGN gene is crucial in regulating mitotic integrity to maintain chromosomal stability and prevents leukemic transformation/progression.
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Affiliation(s)
- Emmanuel K Teye
- Penn State Hershey Cancer Institute and Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - Abigail Sido
- Penn State Hershey Cancer Institute and Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - Ping Xin
- Penn State Hershey Cancer Institute and Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - Niklas K Finnberg
- Department of Hematology/Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA
| | - Prashanth Gokare
- Department of Hematology/Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA
| | - Yuka I Kawasawa
- Institute for Personalized Medicine and Departments of Pharmacology, Biochemistry and Molecular Biology, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - Anna C Salzberg
- Institute for Personalized Medicine and Departments of Pharmacology, Biochemistry and Molecular Biology, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - Sara Shimko
- Penn State Hershey Cancer Institute and Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - Michael Bayerl
- Department of Pathology, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - W Christopher Ehmann
- Penn State Hershey Cancer Institute and Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - David F Claxton
- Penn State Hershey Cancer Institute and Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - Witold B Rybka
- Penn State Hershey Cancer Institute and Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania, USA.,Department of Pathology, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - Joseph J Drabick
- Penn State Hershey Cancer Institute and Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - Hong-Gang Wang
- Department of Pediatrics, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - Thomas Abraham
- Department of Neural and Behavioral Science and the Microscopy Imaging Facility, Pennsylvania State University, Hershey, Pennsylvania, USA
| | - Wafik S El-Deiry
- Department of Hematology/Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA
| | - Robert A Brodsky
- Division of Hematology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Raymond J Hohl
- Penn State Hershey Cancer Institute and Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - Jeffrey J Pu
- Penn State Hershey Cancer Institute and Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania, USA.,Department of Pathology, Penn State University College of Medicine, Hershey, Pennsylvania, USA
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25
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Abstract
Accurate repair of DNA double-strand breaks (DSBs) is carried out by homologous recombination. In order to repair DNA breaks by the recombination pathway, the 5'-terminated DNA strand at DSB sites must be first nucleolytically processed to produce 3'-overhang. The process is termed DNA end resection and involves the interplay of several nuclease complexes. DNA end resection commits DSB repair to the recombination pathway including a process termed single-strand annealing, as resected DNA ends are generally nonligatable by the competing nonhomologous end-joining machinery. Biochemical reconstitution experiments provided invaluable mechanistic insights into the DNA end resection pathways. In this chapter, we describe preparation procedures of key proteins involved in DNA end resection in human cells, including the MRE11-RAD50-NBS1 complex, phosphorylated variant of CtIP, the DNA2 nuclease-helicase with its helicase partners Bloom (BLM) or Werner (WRN), as well as the single-stranded DNA-binding protein replication protein A. The availability of recombinant DNA end resection factors will help to further elucidate resection mechanisms and regulatory processes that may involve novel protein partners and posttranslational modifications.
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Affiliation(s)
- Roopesh Anand
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | - Cosimo Pinto
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland; Institute of Biochemistry, Swiss Federal Institute of Technology, Zurich, Switzerland.
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26
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Genetic Separation of Sae2 Nuclease Activity from Mre11 Nuclease Functions in Budding Yeast. Mol Cell Biol 2017; 37:MCB.00156-17. [PMID: 28970327 DOI: 10.1128/mcb.00156-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 09/25/2017] [Indexed: 02/01/2023] Open
Abstract
Sae2 promotes the repair of DNA double-strand breaks in Saccharomyces cerevisiae The role of Sae2 is linked to the Mre11/Rad50/Xrs2 (MRX) complex, which is important for the processing of DNA ends into single-stranded substrates for homologous recombination. Sae2 has intrinsic endonuclease activity, but the role of this activity has not been assessed independently from its functions in promoting Mre11 nuclease activity. Here we identify and characterize separation-of-function mutants that lack intrinsic nuclease activity or the ability to promote Mre11 endonucleolytic activity. We find that the ability of Sae2 to promote MRX nuclease functions is important for DNA damage survival, particularly in the absence of Dna2 nuclease activity. In contrast, Sae2 nuclease activity is essential for DNA repair when the Mre11 nuclease is compromised. Resection of DNA breaks is impaired when either Sae2 activity is blocked, suggesting roles for both Mre11 and Sae2 nuclease activities in promoting the processing of DNA ends in vivo Finally, both activities of Sae2 are important for sporulation, indicating that the processing of meiotic breaks requires both Mre11 and Sae2 nuclease activities.
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27
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Sgs1 Binding to Rad51 Stimulates Homology-Directed DNA Repair in Saccharomyces cerevisiae. Genetics 2017; 208:125-138. [PMID: 29162625 PMCID: PMC5753853 DOI: 10.1534/genetics.117.300545] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 11/16/2017] [Indexed: 12/23/2022] Open
Abstract
Accurate repair of DNA breaks is essential to maintain genome integrity and cellular fitness. Sgs1, the sole member of the RecQ family of DNA helicases in Saccharomyces cerevisiae, is important for both early and late stages of homology-dependent repair. Its large number of physical and genetic interactions with DNA recombination, repair, and replication factors has established Sgs1 as a key player in the maintenance of genome integrity. To determine the significance of Sgs1 binding to the strand-exchange factor Rad51, we have identified a single amino acid change at the C-terminal of the helicase core of Sgs1 that disrupts Rad51 binding. In contrast to an SGS1 deletion or a helicase-defective sgs1 allele, this new separation-of-function allele, sgs1-FD, does not cause DNA damage hypersensitivity or genome instability, but exhibits negative and positive genetic interactions with sae2Δ, mre11Δ, exo1Δ, srs2Δ, rrm3Δ, and pol32Δ that are distinct from those of known sgs1 mutants. Our findings suggest that the Sgs1-Rad51 interaction stimulates homologous recombination (HR). However, unlike sgs1 mutations, which impair the resection of DNA double-strand ends, negative genetic interactions of the sgs1-FD allele are not suppressed by YKU70 deletion. We propose that the Sgs1-Rad51 interaction stimulates HR by facilitating the formation of the presynaptic Rad51 filament, possibly by Sgs1 competing with single-stranded DNA for replication protein A binding during resection.
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28
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van Leeuwen J, Pons C, Boone C, Andrews BJ. Mechanisms of suppression: The wiring of genetic resilience. Bioessays 2017; 39. [PMID: 28582599 DOI: 10.1002/bies.201700042] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Recent analysis of genome sequences has identified individuals that are healthy despite carrying severe disease-associated mutations. A possible explanation is that these individuals carry a second genomic perturbation that can compensate for the detrimental effects of the disease allele, a phenomenon referred to as suppression. In model organisms, suppression interactions are generally divided into two classes: genomic suppressors which are secondary mutations in the genome that bypass a mutant phenotype, and dosage suppression interactions in which overexpression of a suppressor gene rescues a mutant phenotype. Here, we describe the general properties of genomic and dosage suppression, with an emphasis on the budding yeast. We propose that suppression interactions between genetic variants are likely relevant for determining the penetrance of human traits. Consequently, an understanding of suppression mechanisms may guide the discovery of protective variants in healthy individuals that carry disease alleles, which could direct the rational design of new therapeutics.
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Affiliation(s)
- Jolanda van Leeuwen
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada
| | - Carles Pons
- Institute for Research in Biomedicine (IRB Barcelona), the Barcelona Institute for Science and Technology, Barcelona, Catalonia, Spain
| | - Charles Boone
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Brenda J Andrews
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
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29
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Puddu F, Salguero I, Herzog M, Geisler NJ, Costanzo V, Jackson SP. Chromatin determinants impart camptothecin sensitivity. EMBO Rep 2017; 18:1000-1012. [PMID: 28389464 PMCID: PMC5452016 DOI: 10.15252/embr.201643560] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 03/07/2017] [Accepted: 03/09/2017] [Indexed: 11/09/2022] Open
Abstract
Camptothecin-induced locking of topoisomerase 1 on DNA generates a physical barrier to replication fork progression and creates topological stress. By allowing replisome rotation, absence of the Tof1/Csm3 complex promotes the conversion of impending topological stress to DNA catenation and causes camptothecin hypersensitivity. Through synthetic viability screening, we discovered that histone H4 K16 deacetylation drives the sensitivity of yeast cells to camptothecin and that inactivation of this pathway by mutating H4 K16 or the genes SIR1-4 suppresses much of the hypersensitivity of tof1∆ strains towards this agent. We show that disruption of rDNA or telomeric silencing does not mediate camptothecin resistance but that disruption of Sir1-dependent chromatin domains is sufficient to suppress camptothecin sensitivity in wild-type and tof1∆ cells. We suggest that topoisomerase 1 inhibition in proximity of these domains causes topological stress that leads to DNA hypercatenation, especially in the absence of the Tof1/Csm3 complex. Finally, we provide evidence of the evolutionarily conservation of this mechanism.
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Affiliation(s)
- Fabio Puddu
- The Gurdon Institute and Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Israel Salguero
- The Gurdon Institute and Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Mareike Herzog
- The Gurdon Institute and Department of Biochemistry, University of Cambridge, Cambridge, UK
- The Wellcome Trust Sanger Institute, Hinxton Cambridge, UK
| | - Nicola J Geisler
- The Gurdon Institute and Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Vincenzo Costanzo
- IFOM (Fondazione Istituto FIRC di Oncologia Molecolare), Milan, Italy
| | - Stephen P Jackson
- The Gurdon Institute and Department of Biochemistry, University of Cambridge, Cambridge, UK
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30
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Genetic and biochemical evidences reveal novel insights into the mechanism underlying Saccharomyces cerevisiae Sae2-mediated abrogation of DNA replication stress. J Biosci 2017; 41:615-641. [PMID: 27966484 DOI: 10.1007/s12038-016-9642-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In Saccharomyces cerevisiae, the Mre11-Rad50-Xrs2 (MRX) protein complex plays pivotal roles in double-strand break (DSB) repair, replication stress and telomere length maintenance. Another protein linked to DSB repair is Sae2, which regulates MRX persistence at DSBs. However, very little is known about its role in DNA replication stress and repair. Here, we reveal a crucial role for Sae2 in DNA replication stress. We show that different mutant alleles of SAE2 cause hypersensitivity to genotoxic agents, and when combined with Δmre11 or nuclease-defective mre11 mutant alleles, the double mutants are considerably more sensitive suggesting that the sae2 mutations synergize with mre11 mutations. Biochemical studies demonstrate that Sae2 exists as a dimer in solution, associates preferentially with single-stranded and branched DNA structures, exhibits structure-specific endonuclease activity and cleaves these substrates from the 5' end. Furthermore, we show that the nuclease activity is indeed intrinsic to Sae2. Interestingly, sae2G270D protein possesses DNA-binding activity, but lacks detectable nuclease activity. Altogether, our data suggest a direct role for Sae2 nuclease activity in processing of the DNA structures that arise during replication and DNA damage and provide insights into the mechanism underlying Mre11-Sae2-mediated abrogation of replication stressrelated defects in S. cerevisiae.
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31
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Villa M, Cassani C, Gobbini E, Bonetti D, Longhese MP. Coupling end resection with the checkpoint response at DNA double-strand breaks. Cell Mol Life Sci 2016; 73:3655-63. [PMID: 27141941 PMCID: PMC11108263 DOI: 10.1007/s00018-016-2262-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 04/08/2016] [Accepted: 04/29/2016] [Indexed: 10/21/2022]
Abstract
DNA double-strand breaks (DSBs) are a nasty form of damage that needs to be repaired to ensure genome stability. The DSB ends can undergo a strand-biased nucleolytic processing (resection) to generate 3'-ended single-stranded DNA (ssDNA) that channels DSB repair into homologous recombination. Generation of ssDNA also triggers the activation of the DNA damage checkpoint, which couples cell cycle progression with DSB repair. The checkpoint response is intimately linked to DSB resection, as some checkpoint proteins regulate the resection process. The present review will highlight recent works on the mechanism and regulation of DSB resection and its interplays with checkpoint activation/inactivation in budding yeast.
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Affiliation(s)
- Matteo Villa
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Piazza della Scienza 2, 20126, Milan, Italy
| | - Corinne Cassani
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Piazza della Scienza 2, 20126, Milan, Italy
| | - Elisa Gobbini
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Piazza della Scienza 2, 20126, Milan, Italy
| | - Diego Bonetti
- Institute of Molecular Biology gGmbH (IMB), 55128, Mainz, Germany
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Piazza della Scienza 2, 20126, Milan, Italy.
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32
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Ray Chaudhuri A, Callen E, Ding X, Gogola E, Duarte AA, Lee JE, Wong N, Lafarga V, Calvo JA, Panzarino NJ, John S, Day A, Crespo AV, Shen B, Starnes LM, de Ruiter JR, Daniel JA, Konstantinopoulos PA, Cortez D, Cantor SB, Fernandez-Capetillo O, Ge K, Jonkers J, Rottenberg S, Sharan SK, Nussenzweig A. Replication fork stability confers chemoresistance in BRCA-deficient cells. Nature 2016; 535:382-7. [PMID: 27443740 PMCID: PMC4959813 DOI: 10.1038/nature18325] [Citation(s) in RCA: 699] [Impact Index Per Article: 77.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 04/15/2016] [Indexed: 12/14/2022]
Abstract
Brca1- and Brca2-deficient cells have reduced capacity to repair DNA double-strand breaks (DSBs) by homologous recombination (HR) and consequently are hypersensitive to DNA damaging agents, including cisplatin and poly(ADP-ribose) polymerase (PARP) inhibitors. Here we show that loss of the MLL3/4 complex protein, PTIP, protects Brca1/2-deficient cells from DNA damage and rescues the lethality of Brca2-deficient embryonic stem cells. However, PTIP deficiency does not restore HR activity at DSBs. Instead, its absence inhibits the recruitment of the MRE11 nuclease to stalled replication forks, which in turn protects nascent DNA strands from extensive degradation. More generally, acquisition of PARPi and cisplatin resistance is associated with replication fork (RF) protection in Brca2-deficient tumor cells that do not develop Brca2 reversion mutations. Disruption of multiple proteins, including PARP1 and CHD4, leads to the same end point of RF protection, highlighting the complexities by which tumor cells evade chemotherapeutic interventions and acquire drug resistance.
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Affiliation(s)
- Arnab Ray Chaudhuri
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Elsa Callen
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Xia Ding
- Mouse Cancer Genetics Program, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA
| | - Ewa Gogola
- Division of Molecular Pathology and Cancer Genomics Centre, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Alexandra A Duarte
- Division of Molecular Pathology and Cancer Genomics Centre, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Ji-Eun Lee
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Nancy Wong
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Vanessa Lafarga
- Genomic Instability Group, Spanish National Cancer Research Centre (CNIO), Madrid 28029, Spain
| | - Jennifer A Calvo
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, UMASS Memorial Cancer Center, Worcester, Massachusetts 01605, USA
| | - Nicholas J Panzarino
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, UMASS Memorial Cancer Center, Worcester, Massachusetts 01605, USA
| | - Sam John
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Amanda Day
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Anna Vidal Crespo
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Binghui Shen
- Department of Radiation Biology, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, California 91010, USA
| | - Linda M Starnes
- The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Julian R de Ruiter
- Division of Molecular Pathology and Cancer Genomics Centre, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Jeremy A Daniel
- The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Panagiotis A Konstantinopoulos
- Departments of Gynecologic Medical Oncology, Dana Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - David Cortez
- Department of Biochemistry, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, Tennessee 37232, USA
| | - Sharon B Cantor
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, UMASS Memorial Cancer Center, Worcester, Massachusetts 01605, USA
| | | | - Kai Ge
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jos Jonkers
- Division of Molecular Pathology and Cancer Genomics Centre, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Sven Rottenberg
- Division of Molecular Pathology and Cancer Genomics Centre, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.,Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, 3012 Bern, Switzerland
| | - Shyam K Sharan
- Mouse Cancer Genetics Program, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA
| | - André Nussenzweig
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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33
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Yamamoto K, Wang J, Sprinzen L, Xu J, Haddock CJ, Li C, Lee BJ, Loredan DG, Jiang W, Vindigni A, Wang D, Rabadan R, Zha S. Kinase-dead ATM protein is highly oncogenic and can be preferentially targeted by Topo-isomerase I inhibitors. eLife 2016; 5. [PMID: 27304073 PMCID: PMC4957979 DOI: 10.7554/elife.14709] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 06/14/2016] [Indexed: 12/20/2022] Open
Abstract
Missense mutations in ATM kinase, a master regulator of DNA damage responses, are found in many cancers, but their impact on ATM function and implications for cancer therapy are largely unknown. Here we report that 72% of cancer-associated ATM mutations are missense mutations that are enriched around the kinase domain. Expression of kinase-dead ATM (Atm(KD/-)) is more oncogenic than loss of ATM (Atm(-/-)) in mouse models, leading to earlier and more frequent lymphomas with Pten deletions. Kinase-dead ATM protein (Atm-KD), but not loss of ATM (Atm-null), prevents replication-dependent removal of Topo-isomerase I-DNA adducts at the step of strand cleavage, leading to severe genomic instability and hypersensitivity to Topo-isomerase I inhibitors. Correspondingly, Topo-isomerase I inhibitors effectively and preferentially eliminate Atm(KD/-), but not Atm-proficientor Atm(-/-) leukemia in animal models. These findings identify ATM kinase-domain missense mutations as a potent oncogenic event and a biomarker for Topo-isomerase I inhibitor based therapy.
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Affiliation(s)
- Kenta Yamamoto
- Institute for Cancer Genetics, Columbia Unviersity, New York, United States.,Department of Pathology and Cell Biology, Columbia University, New York, United States.,College of Physicians and Surgeons, Columbia University, New York, United States.,Pathobiology and Molecular Medicine Graduate Program, Columbia University, New York, United States
| | - Jiguang Wang
- Department of Biomedical Informatics, Columbia University, New York, United States.,Department of Systems Biology, Columbia University, New York, United States.,College of Physicians & Surgeons, Columbia University, New York, United States
| | - Lisa Sprinzen
- Institute for Cancer Genetics, Columbia Unviersity, New York, United States.,Department of Pathology and Cell Biology, Columbia University, New York, United States.,College of Physicians and Surgeons, Columbia University, New York, United States.,Pathobiology and Molecular Medicine Graduate Program, Columbia University, New York, United States
| | - Jun Xu
- Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California San Diego, La Jolla, United States
| | - Christopher J Haddock
- Edward A Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, United States
| | - Chen Li
- Institute for Cancer Genetics, Columbia Unviersity, New York, United States.,Department of Pathology and Cell Biology, Columbia University, New York, United States.,College of Physicians and Surgeons, Columbia University, New York, United States
| | - Brian J Lee
- Institute for Cancer Genetics, Columbia Unviersity, New York, United States.,Department of Pathology and Cell Biology, Columbia University, New York, United States.,College of Physicians and Surgeons, Columbia University, New York, United States
| | - Denis G Loredan
- Institute for Cancer Genetics, Columbia Unviersity, New York, United States.,Department of Pathology and Cell Biology, Columbia University, New York, United States.,College of Physicians and Surgeons, Columbia University, New York, United States
| | - Wenxia Jiang
- Institute for Cancer Genetics, Columbia Unviersity, New York, United States.,Department of Pathology and Cell Biology, Columbia University, New York, United States.,College of Physicians and Surgeons, Columbia University, New York, United States
| | - Alessandro Vindigni
- Edward A Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, United States
| | - Dong Wang
- Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California San Diego, La Jolla, United States
| | - Raul Rabadan
- Department of Biomedical Informatics, Columbia University, New York, United States.,Department of Systems Biology, Columbia University, New York, United States.,College of Physicians & Surgeons, Columbia University, New York, United States
| | - Shan Zha
- Institute for Cancer Genetics, Columbia Unviersity, New York, United States.,Department of Pathology and Cell Biology, Columbia University, New York, United States.,College of Physicians and Surgeons, Columbia University, New York, United States.,Division of Pediatric Oncology, Hematology and Stem Cell Transplantation, Columbia University, New York, United States.,Department of Pediatrics, Columbia University, New York, United States.,College of Physicians & Surgeons, Columbia University, New York, United States
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34
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Cussiol JR, Dibitetto D, Pellicioli A, Smolka MB. Slx4 scaffolding in homologous recombination and checkpoint control: lessons from yeast. Chromosoma 2016; 126:45-58. [PMID: 27165041 DOI: 10.1007/s00412-016-0600-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 04/27/2016] [Accepted: 04/29/2016] [Indexed: 01/07/2023]
Abstract
Homologous recombination-mediated DNA repair is essential for maintaining genome integrity. It is a multi-step process that involves resection of DNA ends, strand invasion, DNA synthesis and/or DNA end ligation, and finally, the processing of recombination intermediates such as Holliday junctions or other joint molecules. Over the last 15 years, it has been established that the Slx4 protein plays key roles in the processing of recombination intermediates, functioning as a scaffold to coordinate the action of structure-specific endonucleases. Recent work in budding yeast has uncovered unexpected roles for Slx4 in the initial step of DNA-end resection and in the modulation of DNA damage checkpoint signaling. Here we review these latest findings and discuss the emerging role of yeast Slx4 as an important coordinator of DNA damage signaling responses and a regulator of multiple steps in homologous recombination-mediated repair.
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Affiliation(s)
- José R Cussiol
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Diego Dibitetto
- Department of Biosciences, University of Milan, 20133, Milan, Italy
| | | | - Marcus B Smolka
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA.
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35
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Abstract
The repair of DNA double-strand breaks (DSBs) by homologous recombination (HR) is initiated by nucleolytic degradation of the 5'-terminated strands in a process termed end resection. End resection generates 3'-single-stranded DNA tails, substrates for Rad51 to catalyze homologous pairing and DNA strand exchange, and for activation of the DNA damage checkpoint. The commonly accepted view is that end resection occurs by a two-step mechanism. In the first step, Sae2/CtIP activates the Mre11-Rad50-Xrs2/Nbs1 (MRX/N) complex to endonucleolytically cleave the 5'-terminated DNA strands close to break ends, and in the second step Exo1 and/or Dna2 nucleases extend the resected tracts to produce long 3'-ssDNA-tailed intermediates. Initiation of resection commits a cell to repair a DSB by HR because long ssDNA overhangs are poor substrates for non-homologous end joining (NHEJ). Thus, the initiation of end resection has emerged as a critical control point for repair pathway choice. Here, I review recent studies on the mechanism of end resection and how this process is regulated to ensure the most appropriate repair outcome.
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Affiliation(s)
- Lorraine S Symington
- a Department of Microbiology & Immunology , Columbia University Medical Center , New York , USA
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36
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Chen YJ, Chuang YC, Chuang CN, Cheng YH, Chang CR, Leng CH, Wang TF. S. cerevisiae Mre11 recruits conjugated SUMO moieties to facilitate the assembly and function of the Mre11-Rad50-Xrs2 complex. Nucleic Acids Res 2016; 44:2199-213. [PMID: 26743002 PMCID: PMC4797280 DOI: 10.1093/nar/gkv1523] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 12/19/2015] [Indexed: 01/04/2023] Open
Abstract
Double-strand breaks (DSBs) in chromosomes are the most challenging type of DNA damage. The yeast and mammalian Mre11-Rad50-Xrs2/Nbs1 (MRX/N)-Sae2/Ctp1 complex catalyzes the resection of DSBs induced by secondary structures, chemical adducts or covalently-attached proteins. MRX/N also initiates two parallel DNA damage responses-checkpoint phosphorylation and global SUMOylation-to boost a cell's ability to repair DSBs. However, the molecular mechanism of this SUMO-mediated response is not completely known. In this study, we report that Saccharomyces cerevisiae Mre11 can non-covalently recruit the conjugated SUMO moieties, particularly the poly-SUMO chain. Mre11 has two evolutionarily-conserved SUMO-interacting motifs, Mre11(SIM1) and Mre11(SIM2), which reside on the outermost surface of Mre11. Mre11(SIM1) is indispensable for MRX assembly. Mre11(SIM2) non-covalently links MRX with the SUMO enzymes (E2/Ubc9 and E3/Siz2) to promote global SUMOylation of DNA repair proteins. Mre11(SIM2) acts independently of checkpoint phosphorylation. During meiosis, the mre11(SIM2) mutant, as for mre11S, rad50S and sae2Δ, allows initiation but not processing of Spo11-induced DSBs. Using MRX and DSB repair as a model, our work reveals a general principle in which the conjugated SUMO moieties non-covalently facilitate the assembly and functions of multi-subunit protein complexes.
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Affiliation(s)
- Yu-Jie Chen
- Graduate Program of Biotechnology in Medicine, National Tsing Hua University and National Health Research Institutes, Taiwan Institute of Biotechnology, National Tsing Hua University, Hsinchu 300, Taiwan National Institute of Infectious Diseases and Vaccinology, National Health Research Institute, Miaoli 350, Taiwan Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Yu-Chien Chuang
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Chi-Ning Chuang
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Yun-Hsin Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Chuang-Rung Chang
- Graduate Program of Biotechnology in Medicine, National Tsing Hua University and National Health Research Institutes, Taiwan Institute of Biotechnology, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Chih-Hsiang Leng
- Graduate Program of Biotechnology in Medicine, National Tsing Hua University and National Health Research Institutes, Taiwan National Institute of Infectious Diseases and Vaccinology, National Health Research Institute, Miaoli 350, Taiwan
| | - Ting-Fang Wang
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
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37
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Gobbini E, Villa M, Gnugnoli M, Menin L, Clerici M, Longhese MP. Sae2 Function at DNA Double-Strand Breaks Is Bypassed by Dampening Tel1 or Rad53 Activity. PLoS Genet 2015; 11:e1005685. [PMID: 26584331 PMCID: PMC4652893 DOI: 10.1371/journal.pgen.1005685] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 10/29/2015] [Indexed: 11/30/2022] Open
Abstract
The MRX complex together with Sae2 initiates resection of DNA double-strand breaks (DSBs) to generate single-stranded DNA (ssDNA) that triggers homologous recombination. The absence of Sae2 not only impairs DSB resection, but also causes prolonged MRX binding at the DSBs that leads to persistent Tel1- and Rad53-dependent DNA damage checkpoint activation and cell cycle arrest. Whether this enhanced checkpoint signaling contributes to the DNA damage sensitivity and/or the resection defect of sae2Δ cells is not known. By performing a genetic screen, we identify rad53 and tel1 mutant alleles that suppress both the DNA damage hypersensitivity and the resection defect of sae2Δ cells through an Sgs1-Dna2-dependent mechanism. These suppression events do not involve escaping the checkpoint-mediated cell cycle arrest. Rather, defective Rad53 or Tel1 signaling bypasses Sae2 function at DSBs by decreasing the amount of Rad9 bound at DSBs. As a consequence, reduced Rad9 association to DNA ends relieves inhibition of Sgs1-Dna2 activity, which can then compensate for the lack of Sae2 in DSB resection and DNA damage resistance. We propose that persistent Tel1 and Rad53 checkpoint signaling in cells lacking Sae2 increases the association of Rad9 at DSBs, which in turn inhibits DSB resection by limiting the activity of the Sgs1-Dna2 resection machinery. Genome instability is one of the most pervasive characteristics of cancer cells and can be due to DNA repair defects and failure to arrest the cell cycle. Among the many types of DNA damage, the DNA double strand break (DSB) is one of the most severe, because it can cause mutations and chromosomal rearrangements. Generation of DSBs triggers a highly conserved mechanism, known as DNA damage checkpoint, which arrests the cell cycle until DSBs are repaired. DSBs can be repaired by homologous recombination, which requires the DSB ends to be nucleolytically processed (resected) to generate single-stranded DNA. In Saccharomyces cerevisiae, DSB resection is initiated by the MRX complex together with Sae2, whereas more extensive resection is catalyzed by both Exo1 and Dna2-Sgs1. The absence of Sae2 not only impairs DSB resection, but also leads to the hyperactivation of the checkpoint proteins Tel1/ATM and Rad53, leading to persistent cell cycle arrest. In this manuscript we show that persistent Tel1 and Rad53 signaling activities in sae2Δ cells cause DNA damage hypersensitivity and defective DSB resection by increasing the amount of Rad9 bound at the DSBs, which in turn inhibits the Sgs1-Dna2 resection machinery. As ATM inhibition has been proposed as a strategy for cancer treatment, the finding that defective Tel1 signaling activity restores DNA damage resistance in sae2Δ cells might have implications in cancer therapies that use ATM inhibitors for synthetic lethal approaches that are devised to kill tumor cells with defective DSB repair.
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Affiliation(s)
- Elisa Gobbini
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Matteo Villa
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Marco Gnugnoli
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Luca Menin
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Michela Clerici
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
- * E-mail:
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38
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Cejka P. DNA End Resection: Nucleases Team Up with the Right Partners to Initiate Homologous Recombination. J Biol Chem 2015; 290:22931-8. [PMID: 26231213 DOI: 10.1074/jbc.r115.675942] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The repair of DNA double-strand breaks by homologous recombination commences by nucleolytic degradation of the 5'-terminated strand of the DNA break. This leads to the formation of 3'-tailed DNA, which serves as a substrate for the strand exchange protein Rad51. The nucleoprotein filament then invades homologous DNA to drive template-directed repair. In this review, I discuss mainly the mechanisms of DNA end resection in Saccharomyces cerevisiae, which includes short-range resection by Mre11-Rad50-Xrs2 and Sae2, as well as processive long-range resection by Sgs1-Dna2 or Exo1 pathways. Resection mechanisms are highly conserved between yeast and humans, and analogous machineries are found in prokaryotes as well.
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Affiliation(s)
- Petr Cejka
- From the Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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39
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Forment JV, Jackson SP, Pellegrini L. When two is not enough: a CtIP tetramer is required for DNA repair by Homologous Recombination. Nucleus 2015; 6:344-8. [PMID: 26305173 PMCID: PMC4915501 DOI: 10.1080/19491034.2015.1086050] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 08/17/2015] [Accepted: 08/18/2015] [Indexed: 10/23/2022] Open
Abstract
Homologous recombination (HR) is central to the repair of double-strand DNA breaks that occur in S/G2 phases of the cell cycle. HR relies on the CtIP protein (Ctp1 in fission yeast, Sae2 in budding yeast) for resection of DNA ends, a key step in generating the 3'-DNA overhangs that are required for the HR strand-exchange reaction. Although much has been learned about the biological importance of CtIP in DNA repair, our mechanistic insight into its molecular functions remains incomplete. It has been recently discovered that CtIP and Ctp1 share a conserved tetrameric architecture that is mediated by their N-terminal domains and is critical for their function in HR. The specific arrangement of protein chains in the CtIP/Ctp1 tetramer indicates that an ability to bridge DNA ends might be an important feature of CtIP/Ctp1 function, establishing an intriguing similarity with the known ability of the MRE11-RAD50-NBS1 complex to link DNA ends. Although the exact mechanism of action remains to be elucidated, the remarkable evolutionary conservation of CtIP/Ctp1 tetramerisation clearly points to its crucial role in HR.
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Affiliation(s)
- Josep V Forment
- The Gurdon Institute; University of Cambridge; Cambridge, UK
- The Wellcome Trust Sanger Institute; Hinxton, UK
- Department of Biochemistry; University of Cambridge; Cambridge, UK
| | - Stephen P Jackson
- The Gurdon Institute; University of Cambridge; Cambridge, UK
- The Wellcome Trust Sanger Institute; Hinxton, UK
- Department of Biochemistry; University of Cambridge; Cambridge, UK
| | - Luca Pellegrini
- Department of Biochemistry; University of Cambridge; Cambridge, UK
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