1
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Li S, Tang M, Xiong Y, Feng X, Wang C, Nie L, Huang M, Zhang H, Yin L, Zhu D, Yang C, Ma T, Chen J. Systematic investigation of BRCA1-A, -B, and -C complexes and their functions in DNA damage response and DNA repair. Oncogene 2024:10.1038/s41388-024-03108-y. [PMID: 39068216 DOI: 10.1038/s41388-024-03108-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 07/14/2024] [Accepted: 07/16/2024] [Indexed: 07/30/2024]
Abstract
BRCA1, a breast cancer susceptibility gene, has emerged as a central mediator that brings together multiple signaling complexes in response to DNA damage. The A, B, and C complexes of BRCA1, which are formed based on their phosphorylation-dependent interactions with the BRCA1-C-terminal domains, contribute to the roles of BRCA1 in DNA repair and cell cycle checkpoint control. However, their functions in DNA damage response remain to be fully appreciated. Specifically, there has been no systematic investigation of the roles of BRCA1-A, -B, and -C complexes in the regulation of BRCA1 localization and functions, in part because of cellular lethality associated with loss of CtIP protein, which is an essential component in BRCA1-C complex. To systematically investigate the functions of these complexes in DNA damage response, we depleted a key component in each of these complexes. We used the degradation tag system to inducibly deplete endogenous CtIP and obtained a series of RAP80/FANCJ/CtIP single-, double-, and triple-knockout cells. We showed that loss of BRCA1-B/FANCJ and BRCA1-C/CtIP, but not BRCA1-A/RAP80, resulted in reduced cell proliferation and increased sensitivity to DNA damage. BRCA1-C/CtIP and BRCA1-A/RAP80 were involved in BRCA1 recruitment to sites of DNA damage. However, BRCA1-A/RAP80 was not essential for damage-induced BRCA1 localization. Instead, RAP80/H2AX and CtIP have redundant roles in BRCA1 recruitment. Altogether, our systematic analysis uncovers functional differences between BRCA1-A, -B, and -C complexes and provides new insights into the roles of these BRCA1-associated protein complexes in DNA damage response and DNA repair.
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Affiliation(s)
- Siting Li
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Mengfan Tang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Department of Immunology, School of Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yun Xiong
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Xu Feng
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Chao Wang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Litong Nie
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Min Huang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Huimin Zhang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Ling Yin
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Dandan Zhu
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Chang Yang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Tiantian Ma
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Junjie Chen
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
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2
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Lokanathan Balaji S, De Bragança S, Balaguer-Pérez F, Northall S, Wilkinson OJ, Aicart-Ramos C, Seetaloo N, Sobott F, Moreno-Herrero F, Dillingham MS. DNA binding and bridging by human CtIP in the healthy and diseased states. Nucleic Acids Res 2024:gkae538. [PMID: 38922686 DOI: 10.1093/nar/gkae538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 06/05/2024] [Accepted: 06/13/2024] [Indexed: 06/28/2024] Open
Abstract
The human DNA repair factor CtIP helps to initiate the resection of double-stranded DNA breaks for repair by homologous recombination, in part through its ability to bind and bridge DNA molecules. However, CtIP is a natively disordered protein that bears no apparent similarity to other DNA-binding proteins and so the structural basis for these activities remains unclear. In this work, we have used bulk DNA binding, single molecule tracking, and DNA bridging assays to study wild-type and variant CtIP proteins to better define the DNA binding domains and the effects of mutations associated with inherited human disease. Our work identifies a monomeric DNA-binding domain in the C-terminal region of CtIP. CtIP binds non-specifically to DNA and can diffuse over thousands of nucleotides. CtIP-mediated bridging of distant DNA segments is observed in single-molecule magnetic tweezers experiments. However, we show that binding alone is insufficient for DNA bridging, which also requires tetramerization via the N-terminal domain. Variant CtIP proteins associated with Seckel and Jawad syndromes display impaired DNA binding and bridging activities. The significance of these findings in the context of facilitating DNA break repair is discussed.
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Affiliation(s)
- Shreya Lokanathan Balaji
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Sara De Bragança
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049, Spain
| | - Francisco Balaguer-Pérez
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049, Spain
| | - Sarah Northall
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Oliver John Wilkinson
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Clara Aicart-Ramos
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049, Spain
| | - Neeleema Seetaloo
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Frank Sobott
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Fernando Moreno-Herrero
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049, Spain
| | - Mark Simon Dillingham
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
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3
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Hosen MB, Kawasumi R, Hirota K. Dominant roles of BRCA1 in cellular tolerance to a chain-terminating nucleoside analog, alovudine. DNA Repair (Amst) 2024; 137:103668. [PMID: 38460389 DOI: 10.1016/j.dnarep.2024.103668] [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: 12/24/2023] [Revised: 02/28/2024] [Accepted: 03/01/2024] [Indexed: 03/11/2024]
Abstract
Alovudine is a chain-terminating nucleoside analog (CTNA) that is frequently used as an antiviral and anticancer agent. Generally, CTNAs inhibit DNA replication after their incorporation into nascent DNA during DNA synthesis by suppressing subsequent polymerization, which restricts the proliferation of viruses and cancer cells. Alovudine is a thymidine analog used as an antiviral drug. However, the mechanisms underlying the removal of alovudine and DNA damage tolerance pathways involved in cellular resistance to alovudine remain unclear. Here, we explored the DNA damage tolerance pathways responsible for cellular tolerance to alovudine and found that BRCA1-deficient cells exhibited the highest sensitivity to alovudine. Moreover, alovudine interfered with DNA replication in two distinct mechanisms: first: alovudine incorporated at the end of nascent DNA interfered with subsequent DNA synthesis; second: DNA replication stalled on the alovudine-incorporated template strand. Additionally, BRCA1 facilitated the removal of the incorporated alovudine from nascent DNA, and BRCA1-mediated homologous recombination (HR) contributed to the progressive replication on the alovudine-incorporated template. Thus, we have elucidated the previously unappreciated mechanism of alovudine-mediated inhibition of DNA replication and the role of BRCA1 in cellular tolerance to alovudine.
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Affiliation(s)
- Md Bayejid Hosen
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Ryotaro Kawasumi
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Kouji Hirota
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan.
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4
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Ahmad T, Kawasumi R, Taniguchi T, Abe T, Terada K, Tsuda M, Shimizu N, Tsurimoto T, Takeda S, Hirota K. The proofreading exonuclease of leading-strand DNA polymerase epsilon prevents replication fork collapse at broken template strands. Nucleic Acids Res 2023; 51:12288-12302. [PMID: 37944988 PMCID: PMC10711444 DOI: 10.1093/nar/gkad999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 10/03/2023] [Accepted: 10/17/2023] [Indexed: 11/12/2023] Open
Abstract
Leading-strand DNA replication by polymerase epsilon (Polϵ) across single-strand breaks (SSBs) causes single-ended double-strand breaks (seDSBs), which are repaired via homology-directed repair (HDR) and suppressed by fork reversal (FR). Although previous studies identified many molecules required for hydroxyurea-induced FR, FR at seDSBs is poorly understood. Here, we identified molecules that specifically mediate FR at seDSBs. Because FR at seDSBs requires poly(ADP ribose)polymerase 1 (PARP1), we hypothesized that seDSB/FR-associated molecules would increase tolerance to camptothecin (CPT) but not the PARP inhibitor olaparib, even though both anti-cancer agents generate seDSBs. Indeed, we uncovered that Polϵ exonuclease and CTF18, a Polϵ cofactor, increased tolerance to CPT but not olaparib. To explore potential functional interactions between Polϵ exonuclease, CTF18, and PARP1, we created exonuclease-deficient POLE1exo-/-, CTF18-/-, PARP1-/-, CTF18-/-/POLE1exo-/-, PARP1-/-/POLE1exo-/-, and CTF18-/-/PARP1-/- cells. Epistasis analysis indicated that Polϵ exonuclease and CTF18 were interdependent and required PARP1 for CPT tolerance. Remarkably, POLE1exo-/- and HDR-deficient BRCA1-/- cells exhibited similar CPT sensitivity. Moreover, combining POLE1exo-/- with BRCA1-/- mutations synergistically increased CPT sensitivity. In conclusion, the newly identified PARP1-CTF18-Polϵ exonuclease axis and HDR act independently to prevent fork collapse at seDSBs. Olaparib inhibits this axis, explaining the pronounced cytotoxic effects of olaparib on HDR-deficient cells.
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Affiliation(s)
- Tasnim Ahmad
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Ryotaro Kawasumi
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Tomoya Taniguchi
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Takuya Abe
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Kazuhiro Terada
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Masataka Tsuda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo-ku, Kyoto 606-8501, Japan
- Program of Mathematical and Life Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki 210-9501, Japan
| | - Naoto Shimizu
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo-ku, Kyoto 606-8501, Japan
- Program of Mathematical and Life Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Toshiki Tsurimoto
- Department of Biology, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Shunichi Takeda
- Shenzhen University, School of Medicine, Shenzhen, Guangdong 518060, China
| | - Kouji Hirota
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
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5
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Zhang H, Xiong Y, Sun Y, Park JM, Su D, Feng X, Keast S, Tang M, Huang M, Wang C, Srivastava M, Yang C, Zhu D, Chen Z, Li S, Yin L, Pommier Y, Chen J. RAD54L2-mediated DNA damage avoidance pathway specifically preserves genome integrity in response to topoisomerase 2 poisons. SCIENCE ADVANCES 2023; 9:eadi6681. [PMID: 38055811 PMCID: PMC10699775 DOI: 10.1126/sciadv.adi6681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 11/07/2023] [Indexed: 12/08/2023]
Abstract
Type II topoisomerases (TOP2) form transient TOP2 cleavage complexes (TOP2ccs) during their catalytic cycle to relieve topological stress. TOP2ccs are covalently linked TOP2-DNA intermediates that are reversible but can be trapped by TOP2 poisons. Trapped TOP2ccs block transactions on DNA and generate genotoxic stress, which are the mechanisms of action of TOP2 poisons. How cells avoid TOP2cc accumulation remains largely unknown. In this study, we uncovered RAD54 like 2 (RAD54L2) as a key factor that mediates a TOP2-specific DNA damage avoidance pathway. RAD54L2 deficiency conferred unique sensitivity to treatment with TOP2 poisons. RAD54L2 interacted with TOP2A/TOP2B and ZATT/ZNF451 and promoted the turnover of TOP2 from DNA with or without TOP2 poisons. Additionally, inhibition of proteasome activity enhanced the chromatin binding of RAD54L2, which in turn led to the removal of TOP2 from chromatin. In conclusion, we propose that RAD54L2-mediated TOP2 turnover is critically important for the avoidance of potential TOP2-linked DNA damage under physiological conditions and in response to TOP2 poisons.
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Affiliation(s)
- Huimin Zhang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yun Xiong
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yilun Sun
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892, USA
| | - Jeong-Min Park
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Dan Su
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Xu Feng
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Sarah Keast
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Mengfan Tang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Min Huang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Chao Wang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Mrinal Srivastava
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Chang Yang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Dandan Zhu
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Zhen Chen
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Siting Li
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Ling Yin
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yves Pommier
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892, USA
| | - Junjie Chen
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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6
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Zhong AX, Chen Y, Chen PL. BRCA1 the Versatile Defender: Molecular to Environmental Perspectives. Int J Mol Sci 2023; 24:14276. [PMID: 37762577 PMCID: PMC10532398 DOI: 10.3390/ijms241814276] [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: 08/17/2023] [Revised: 09/13/2023] [Accepted: 09/14/2023] [Indexed: 09/29/2023] Open
Abstract
The evolving history of BRCA1 research demonstrates the profound interconnectedness of a single protein within the web of crucial functions in human cells. Mutations in BRCA1, a tumor suppressor gene, have been linked to heightened breast and ovarian cancer risks. However, despite decades of extensive research, the mechanisms underlying BRCA1's contribution to tissue-specific tumor development remain elusive. Nevertheless, much of the BRCA1 protein's structure, function, and interactions has been elucidated. Individual regions of BRCA1 interact with numerous proteins to play roles in ubiquitination, transcription, cell checkpoints, and DNA damage repair. At a cellular scale, these BRCA1 functions coordinate tumor suppression, R-loop prevention, and cellular differentiation, all of which may contribute to BRCA1's role in cancer tissue specificity. As research on BRCA1 and breast cancer continues to evolve, it will become increasingly evident that modern materials such as Bisphenol A should be examined for their relationship with DNA stability, cancer incidence, and chemotherapy. Overall, this review offers a comprehensive understanding of BRCA1's many roles at a molecular, cellular, organismal, and environmental scale. We hope that the knowledge gathered here highlights both the necessity of BRCA1 research and the potential for novel strategies to prevent and treat cancer in individuals carrying BRCA1 mutations.
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Affiliation(s)
- Amy X. Zhong
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA;
| | - Yumay Chen
- Department of Medicine, Division of Endocrinology, University of California, Irvine, CA 92697, USA;
| | - Phang-Lang Chen
- Department of Biological Chemistry, University of California, Irvine, CA 92697, USA
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7
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Guha Majumdar A, Shree S, Das A, Kumar BK, Dey P, Subramanian M, Patro BS. Design, synthesis and development of a dual inhibitor of Topoisomerase 1 and poly (ADP-ribose) polymerase 1 for efficient killing of cancer cells. Eur J Med Chem 2023; 258:115598. [PMID: 37406384 DOI: 10.1016/j.ejmech.2023.115598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/16/2023] [Accepted: 06/23/2023] [Indexed: 07/07/2023]
Abstract
Combinatorial inhibition of Topoisomerase 1 (TOP1) and Poly (ADP-ribose) polymerase 1 (PARP1) is an attractive therapeutic strategy which is under active investigation to address chemoresistance to TOP1 inhibitors. However, this combinatorial regimen suffers from severe dose limiting toxicities. Dual inhibitors often offer significant advantages over combinatorial therapies involving individual agents by minimizing toxicity and providing conducive pharmacokinetic profiles. In this study, we have designed, synthesized and evaluated a library of 11 candidate conjugated dual inhibitors for PARP1 and TOP1, named as DiPT-1 to DiPT-11. Our extensive screening showed that one of the hits i.e.DiPT-4 has promising cytotoxicity profile against multiple cancers with limited toxicities towards normal cells. DiPT-4 induces extensive DNA double stand breaks (DSBs), cell cycle arrest and apoptosis in cancer cells. Mechanistically, DiPT-4 has the propensity to bind catalytic pockets of TOP1 and PARP1, leading to significant inhibition of both TOP1 and PARP1 at in vitro and cellular level. Interestingly, DiPT-4 causes extensive stabilization of TOP1-DNA covalent complex (TOP1cc), a key lethal intermediate associated with induction of DSBs and cell death. Moreover, DiPT-4 inhibited poly (ADP-ribosylation) i.e. PARylation of TOP1cc, leading to long lived TOP1cc with a slower kinetics of degradation. This is one of the important molecular processes which helps in overcoming resistance in cancer in response to TOP1 inhibitors. Together, our investigation showed DiPT-4 as a promising dual inhibitor of TOP1 and PARP1, which may have the potential to offer significant advantages over combinatorial therapy in clinical settings.
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Affiliation(s)
- Ananda Guha Majumdar
- Bio-Organic Division, India; Homi Bhabha National Institute, Mumbai, Maharashtra, 400094, India
| | - Shikha Shree
- Bio-Organic Division, India; Homi Bhabha National Institute, Mumbai, Maharashtra, 400094, India
| | - Amit Das
- Radiation Biology & Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, 400085, India; Homi Bhabha National Institute, Mumbai, Maharashtra, 400094, India
| | - Binita K Kumar
- Radiation Biology & Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, 400085, India
| | | | - Mahesh Subramanian
- Bio-Organic Division, India; Homi Bhabha National Institute, Mumbai, Maharashtra, 400094, India
| | - Birija Sankar Patro
- Bio-Organic Division, India; Homi Bhabha National Institute, Mumbai, Maharashtra, 400094, India.
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8
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Washif M, Ahmad T, Hosen MB, Rahman MR, Taniguchi T, Okubo H, Hirota K, Kawasumi R. CTF18-RFC contributes to cellular tolerance against chain-terminating nucleoside analogs (CTNAs) in cooperation with proofreading exonuclease activity of DNA polymerase ε. DNA Repair (Amst) 2023; 127:103503. [PMID: 37099849 DOI: 10.1016/j.dnarep.2023.103503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 04/10/2023] [Accepted: 04/18/2023] [Indexed: 04/28/2023]
Abstract
Chemotherapeutic nucleoside analogs, such as cytarabine (Ara-C), are incorporated into genomic DNA during replication. Incorporated Ara-CMP (Ara-cytidine monophosphate) serves as a chain terminator and inhibits DNA synthesis by replicative polymerase epsilon (Polε). The proofreading exonuclease activity of Polε removes the misincorporated Ara-CMP, thereby contributing to the cellular tolerance to Ara-C. Purified Polε performs proofreading, and it is generally believed that proofreading in vivo does not need additional factors. In this study, we demonstrated that the proofreading by Polε in vivo requires CTF18, a component of the leading-strand replisome. We found that loss of CTF18 in chicken DT40 cells and human TK6 cells results in hypersensitivity to Ara-C, indicating the conserved function of CTF18 in the cellular tolerance of Ara-C. Strikingly, we found that proofreading-deficient POLE1D269A/-, CTF18-/-, and POLE1D269A/-/CTF18-/- cells showed indistinguishable phenotypes, including the extent of hypersensitivity to Ara-C and decreased replication rate with Ara-C. This observed epistatic relationship between POLE1D269A/- and CTF18-/- suggests that they are interdependent in removing mis-incorporated Ara-CMP from the 3' end of primers. Mechanistically, we found that CTF18-/- cells have reduced levels of chromatin-bound Polε upon Ara-C treatment, suggesting that CTF18 contributes to the tethering of Polε on fork at the stalled end and thereby facilitating the removal of inserted Ara-C. Collectively, these data reveal the previously unappreciated role of CTF18 in Polε-exonuclease-mediated maintenance of the replication fork upon Ara-C incorporation.
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Affiliation(s)
- Mubasshir Washif
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Tasnim Ahmad
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Md Bayejid Hosen
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Md Ratul Rahman
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Tomoya Taniguchi
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Hiromori Okubo
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Kouji Hirota
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Ryotaro Kawasumi
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan.
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9
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Ceppi I, Cannavo E, Bret H, Camarillo R, Vivalda F, Thakur RS, Romero-Franco A, Sartori AA, Huertas P, Guérois R, Cejka P. PLK1 regulates CtIP and DNA2 interplay in long-range DNA end resection. Genes Dev 2023; 37:119-135. [PMID: 36746606 PMCID: PMC10069449 DOI: 10.1101/gad.349981.122] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 01/12/2023] [Indexed: 02/08/2023]
Abstract
DNA double-strand break (DSB) repair is initiated by DNA end resection. CtIP acts in short-range resection to stimulate MRE11-RAD50-NBS1 (MRN) to endonucleolytically cleave 5'-terminated DNA to bypass protein blocks. CtIP also promotes the DNA2 helicase-nuclease to accelerate long-range resection downstream from MRN. Here, using AlphaFold2, we identified CtIP-F728E-Y736E as a separation-of-function mutant that is still proficient in conjunction with MRN but is not able to stimulate ssDNA degradation by DNA2. Accordingly, CtIP-F728E-Y736E impairs physical interaction with DNA2. Cellular assays revealed that CtIP-F728E-Y736E cells exhibit reduced DSB-dependent chromatin-bound RPA, impaired long-range resection, and increased sensitivity to DSB-inducing drugs. Previously, CtIP was shown to be targeted by PLK1 to inhibit long-range resection, yet the underlying mechanism was unclear. We show that the DNA2-interacting region in CtIP includes the PLK1 target site at S723. The integrity of S723 in CtIP is necessary for the stimulation of DNA2, and phosphorylation of CtIP by PLK1 in vitro is consequently inhibitory, explaining why PLK1 restricts long-range resection. Our data support a model in which CDK-dependent phosphorylation of CtIP activates resection by MRN in S phase, and PLK1-mediated phosphorylation of CtIP disrupts CtIP stimulation of DNA2 to attenuate long-range resection later at G2/M.
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Affiliation(s)
- Ilaria Ceppi
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona 6500, Switzerland
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich 8093, Switzerland
| | - Elda Cannavo
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona 6500, Switzerland
| | - Hélène Bret
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette 91190, France
| | - Rosa Camarillo
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla 41080, Spain
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide, Sevilla 41092, Spain
| | - Francesca Vivalda
- Institute of Molecular Cancer Research, University of Zürich, Zürich 8057, Switzerland
| | - Roshan Singh Thakur
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona 6500, Switzerland
| | - Amador Romero-Franco
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla 41080, Spain
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide, Sevilla 41092, Spain
| | - Alessandro A Sartori
- Institute of Molecular Cancer Research, University of Zürich, Zürich 8057, Switzerland
| | - Pablo Huertas
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla 41080, Spain
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide, Sevilla 41092, Spain
| | - Raphaël Guérois
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette 91190, France
| | - Petr Cejka
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona 6500, Switzerland;
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich 8093, Switzerland
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10
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ATM suppresses c-Myc overexpression in the mammary epithelium in response to estrogen. Cell Rep 2023; 42:111909. [PMID: 36640339 PMCID: PMC10023214 DOI: 10.1016/j.celrep.2022.111909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 10/27/2022] [Accepted: 12/12/2022] [Indexed: 12/31/2022] Open
Abstract
ATM gene mutation carriers are predisposed to estrogen-receptor-positive breast cancer (BC). ATM prevents BC oncogenesis by activating p53 in every cell; however, much remains unknown about tissue-specific oncogenesis after ATM loss. Here, we report that ATM controls the early transcriptional response to estrogens. This response depends on topoisomerase II (TOP2), which generates TOP2-DNA double-strand break (DSB) complexes and rejoins the breaks. When TOP2-mediated ligation fails, ATM facilitates DSB repair. After estrogen exposure, TOP2-dependent DSBs arise at the c-MYC enhancer in human BC cells, and their defective repair changes the activation profile of enhancers and induces the overexpression of many genes, including the c-MYC oncogene. CRISPR/Cas9 cleavage at the enhancer also causes c-MYC overexpression, indicating that this DSB causes c-MYC overexpression. Estrogen treatment induced c-Myc protein overexpression in mammary epithelial cells of ATM-deficient mice. In conclusion, ATM suppresses the c-Myc-driven proliferative effects of estrogens, possibly explaining such tissue-specific oncogenesis.
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11
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The Lipophilic Purine Nucleoside-Tdp1 Inhibitor-Enhances DNA Damage Induced by Topotecan In Vitro and Potentiates the Antitumor Effect of Topotecan In Vivo. Molecules 2022; 28:molecules28010323. [PMID: 36615517 PMCID: PMC9822400 DOI: 10.3390/molecules28010323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 12/20/2022] [Accepted: 12/28/2022] [Indexed: 01/03/2023] Open
Abstract
The use of cancer chemotherapy sensitizers is a promising approach to induce the effect of clinically used anticancer treatments. One of the interesting targets is Tyrosyl-DNA Phosphodiesterase 1 (Tdp1), a DNA-repair enzyme, that may prevent the action of clinical Topoisomerase 1 (Top1) inhibitors, such as topotecan (Tpc). Tdp1 eliminates covalent Top1-DNA (Top1c) complexes that appear under the action of topotecan and determines the cytotoxic effect of this drug. We hypothesize that Tdp1 inhibition would sensitize cells towards the effect of Tpc. Herein, we report the synthesis and study of lipophilic derivatives of purine nucleosides that efficiently suppress Tdp1 activity, with IC50 values in the 0.3-22.0 μM range. We also showed that this compound class can enhance DNA damage induced by topotecan in vitro by Comet assay on human cell lines HeLa and potentiate the antitumor effect of topotecan in vivo on a mice ascitic Krebs-2 carcinoma model. Thereby, this type of compound may be useful to develop drugs, that sensitize the effect of topotecan and reduce the required dose and, as a result, side effects.
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12
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Uusküla-Reimand L, Wilson MD. Untangling the roles of TOP2A and TOP2B in transcription and cancer. SCIENCE ADVANCES 2022; 8:eadd4920. [PMID: 36322662 PMCID: PMC9629710 DOI: 10.1126/sciadv.add4920] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 09/12/2022] [Indexed: 06/09/2023]
Abstract
Type II topoisomerases (TOP2) are conserved regulators of chromatin topology that catalyze reversible DNA double-strand breaks (DSBs) and are essential for maintaining genomic integrity in diverse dynamic processes such as transcription, replication, and cell division. While controlled TOP2-mediated DSBs are an elegant solution to topological constraints of DNA, DSBs also contribute to the emergence of chromosomal translocations and mutations that drive cancer. The central importance of TOP2 enzymes as frontline chemotherapeutic targets is well known; however, their precise biological functions and impact in cancer development are still poorly understood. In this review, we provide an updated overview of TOP2A and TOP2B in the regulation of chromatin topology and transcription, and discuss the recent discoveries linking TOP2 activities with cancer pathogenesis.
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Affiliation(s)
- Liis Uusküla-Reimand
- Genetics and Genome Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
| | - Michael D. Wilson
- Genetics and Genome Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
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13
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Sun Y, Soans E, Mishina M, Petricci E, Pommier Y, Nitiss KC, Nitiss JL. Requirements for MRN endonuclease processing of topoisomerase II-mediated DNA damage in mammalian cells. Front Mol Biosci 2022; 9:1007064. [PMID: 36213114 PMCID: PMC9537633 DOI: 10.3389/fmolb.2022.1007064] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 08/29/2022] [Indexed: 12/03/2022] Open
Abstract
During a normal topoisomerase II (TOP2) reaction, the enzyme forms a covalent enzyme DNA intermediate consisting of a 5′ phosphotyrosyl linkage between the enzyme and DNA. While the enzyme typically rejoins the transient breakage after strand passage, a variety of conditions including drugs targeting TOP2 can inhibit DNA resealing, leading to enzyme-mediated DNA damage. A critical aspect of the repair of TOP2-mediated damage is the removal of the TOP2 protein covalently bound to DNA. While proteolysis plays a role in repairing this damage, nucleolytic enzymes must remove the phosphotyrosyl-linked peptide bound to DNA. The MRN complex has been shown to participate in the removal of TOP2 protein from DNA following cellular treatment with TOP2 poisons. In this report we used an optimized ICE (In vivo Complex of Enzyme) assay to measure covalent TOP2/DNA complexes. In agreement with previous independent reports, we find that the absence or inhibition of the MRE11 endonuclease results in elevated levels of both TOP2α and TOP2β covalent complexes. We also examined levels of TOP2 covalent complexes in cells treated with the proteasome inhibitor MG132. Although MRE11 inhibition plus MG132 was not synergistic in etoposide-treated cells, ectopic overexpression of MRE11 resulted in removal of TOP2 even in the presence of MG132. We also found that VCP/p97 inhibition led to elevated TOP2 covalent complexes and prevented the removal of TOP2 covalent complexes by MRE11 overexpression. Our results demonstrate the existence of multiple pathways for proteolytic processing of TOP2 prior to nucleolytic processing, and that MRE11 can process TOP2 covalent complexes even when the proteasome is inhibited. The interactions between VCP/p97 and proteolytic processing of TOP2 covalent complexes merit additional investigation.
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Affiliation(s)
- Yilun Sun
- Pharmaceutical Sciences Department, University of Illinois College of Pharmacy, Rockford, IL, United States
- Laboratory of Molecular Pharmacology, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
- *Correspondence: Yilun Sun, ; John L. Nitiss,
| | - Eroica Soans
- St. Jude Children’s Research Hospital Memphis, Memphis, TN, United States
| | - Margarita Mishina
- St. Jude Children’s Research Hospital Memphis, Memphis, TN, United States
| | | | - Yves Pommier
- Laboratory of Molecular Pharmacology, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Karin C. Nitiss
- Pharmaceutical Sciences Department, University of Illinois College of Pharmacy, Rockford, IL, United States
| | - John L. Nitiss
- Pharmaceutical Sciences Department, University of Illinois College of Pharmacy, Rockford, IL, United States
- *Correspondence: Yilun Sun, ; John L. Nitiss,
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14
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Gupta P, Majumdar AG, Patro BS. Non-enzymatic function of WRN RECQL helicase regulates removal of topoisomerase-I-DNA covalent complexes and triggers NF-κB signaling in cancer. Aging Cell 2022; 21:e13625. [PMID: 35582959 PMCID: PMC9197415 DOI: 10.1111/acel.13625] [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: 10/20/2021] [Revised: 03/25/2022] [Accepted: 04/20/2022] [Indexed: 11/26/2022] Open
Abstract
Mutation in Werner (WRN) RECQL helicase is associated with premature aging syndrome (Werner syndrome, WS) and predisposition to multiple cancers. In patients with solid cancers, deficiency of the WRN RECQL helicase is paradoxically associated with enhanced overall survival in response to treatment with TOP1 inhibitors, which stabilize pathological TOP1‐DNA‐covalent‐complexes (TOP1cc) on the genome. However, the underlying mechanism of WRN in development of chemoresistance to TOP1 inhibitors is not yet explored. Our whole‐genome transcriptomic analysis for ~25,000 genes showed robust activation of NF‐κB‐dependent prosurvival genes in response to TOP1cc. CRISPR‐Cas9 knockout, shRNA silencing, and under‐expression of WRN confer high‐sensitivity of multiple cancers to TOP1 inhibitor. We demonstrated that WRN orchestrates TOP1cc repair through proteasome‐dependent and proteasome‐independent process, unleashing robust ssDNA generation. This in turn ensues signal transduction for CHK1 mediated NF‐κB‐activation through IκBα‐degradation and nuclear localization of p65 protein. Intriguingly, our site‐directed mutagenesis and rescue experiments revealed that neither RECQL‐helicase nor DNA‐exonuclease enzyme activity of WRN (WRNE84A, WRNK577M, and WRNE84A‐K577M) were required for TOP1cc removal, ssDNA generation and signaling for NF‐κB activation. In correlation with patient data and above results, the TOP1 inhibitor‐based targeted therapy showed that WRN‐deficient melanoma tumors were highly sensitive to TOP1 inhibition in preclinical in vivo mouse model. Collectively, our findings identify hitherto unknown non‐enzymatic role of WRN RECQL helicase in pathological mechanisms underlying TOP1cc processing and subsequent NF‐κB‐activation, offering a potential targeted therapy for WRN‐deficient cancer patients.
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Affiliation(s)
- Pooja Gupta
- Bio‐Organic Division Bhabha Atomic Research Centre Trombay Mumbai India
- Homi Bhabha National Institute Anushaktinagar Mumbai India
| | - Ananda Guha Majumdar
- Bio‐Organic Division Bhabha Atomic Research Centre Trombay Mumbai India
- Homi Bhabha National Institute Anushaktinagar Mumbai India
| | - Birija Sankar Patro
- Bio‐Organic Division Bhabha Atomic Research Centre Trombay Mumbai India
- Homi Bhabha National Institute Anushaktinagar Mumbai India
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15
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Bolck HA, Przetocka S, Meier R, von Aesch C, Zurfluh C, Hänggi K, Spegg V, Altmeyer M, Stebler M, Nørrelykke SF, Horvath P, Sartori AA, Porro A. RNAi Screening Uncovers a Synthetic Sick Interaction between CtIP and the BARD1 Tumor Suppressor. Cells 2022; 11:643. [PMID: 35203293 PMCID: PMC8870135 DOI: 10.3390/cells11040643] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 02/07/2022] [Accepted: 02/10/2022] [Indexed: 11/23/2022] Open
Abstract
Human CtIP is best known for its role in DNA end resection to initiate DNA double-strand break repair by homologous recombination. Recently, CtIP has also been shown to protect reversed replication forks from nucleolytic degradation upon DNA replication stress. However, still little is known about the DNA damage response (DDR) networks that preserve genome integrity and sustain cell survival in the context of CtIP insufficiency. Here, to reveal such potential buffering relationships, we screened a DDR siRNA library in CtIP-deficient cells to identify candidate genes that induce synthetic sickness/lethality (SSL). Our analyses unveil a negative genetic interaction between CtIP and BARD1, the heterodimeric binding partner of BRCA1. We found that simultaneous disruption of CtIP and BARD1 triggers enhanced apoptosis due to persistent replication stress-induced DNA lesions giving rise to chromosomal abnormalities. Moreover, we observed that the genetic interaction between CtIP and BARD1 occurs independently of the BRCA1-BARD1 complex formation and might be, therefore, therapeutical relevant for the treatment of BRCA-defective tumors.
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Affiliation(s)
- Hella A. Bolck
- Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland; (H.A.B.); (S.P.); (C.v.A.); (C.Z.); (K.H.)
- Institute of Pathology and Molecular Pathology, University Hospital Zurich, 8091 Zurich, Switzerland
| | - Sara Przetocka
- Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland; (H.A.B.); (S.P.); (C.v.A.); (C.Z.); (K.H.)
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Roger Meier
- Scientific Center for Optical and Electron Microscopy (ScopeM), ETH Zurich, 8093 Zurich, Switzerland; (R.M.); (M.S.); (S.F.N.)
| | - Christine von Aesch
- Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland; (H.A.B.); (S.P.); (C.v.A.); (C.Z.); (K.H.)
| | - Christina Zurfluh
- Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland; (H.A.B.); (S.P.); (C.v.A.); (C.Z.); (K.H.)
| | - Kay Hänggi
- Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland; (H.A.B.); (S.P.); (C.v.A.); (C.Z.); (K.H.)
- Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, USA
| | - Vincent Spegg
- Department of Molecular Mechanisms of Disease, University of Zurich, 8057 Zurich, Switzerland; (V.S.); (M.A.)
| | - Matthias Altmeyer
- Department of Molecular Mechanisms of Disease, University of Zurich, 8057 Zurich, Switzerland; (V.S.); (M.A.)
| | - Michael Stebler
- Scientific Center for Optical and Electron Microscopy (ScopeM), ETH Zurich, 8093 Zurich, Switzerland; (R.M.); (M.S.); (S.F.N.)
| | - Simon F. Nørrelykke
- Scientific Center for Optical and Electron Microscopy (ScopeM), ETH Zurich, 8093 Zurich, Switzerland; (R.M.); (M.S.); (S.F.N.)
| | - Peter Horvath
- Synthetic and System Biology Unit, Biological Research Center (BRC), 6726 Szeged, Hungary;
- Institute for Molecular Medicine Finland, University of Helsinki, 00014 Helsinki, Finland
| | - Alessandro A. Sartori
- Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland; (H.A.B.); (S.P.); (C.v.A.); (C.Z.); (K.H.)
| | - Antonio Porro
- Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland; (H.A.B.); (S.P.); (C.v.A.); (C.Z.); (K.H.)
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16
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Clay DE, Bretscher HS, Jezuit EA, Bush KB, Fox DT. Persistent DNA damage signaling and DNA polymerase theta promote broken chromosome segregation. J Cell Biol 2021; 220:e202106116. [PMID: 34613334 PMCID: PMC8500225 DOI: 10.1083/jcb.202106116] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 08/24/2021] [Accepted: 09/14/2021] [Indexed: 01/16/2023] Open
Abstract
Cycling cells must respond to DNA double-strand breaks (DSBs) to avoid genome instability. Missegregation of chromosomes with DSBs during mitosis results in micronuclei, aberrant structures linked to disease. How cells respond to DSBs during mitosis is incompletely understood. We previously showed that Drosophilamelanogaster papillar cells lack DSB checkpoints (as observed in many cancer cells). Here, we show that papillar cells still recruit early acting repair machinery (Mre11 and RPA3) and the Fanconi anemia (FA) protein Fancd2 to DSBs. These proteins persist as foci on DSBs as cells enter mitosis. Repair foci are resolved in a stepwise manner during mitosis. DSB repair kinetics depends on both monoubiquitination of Fancd2 and the alternative end-joining protein DNA polymerase θ. Disruption of either or both of these factors causes micronuclei after DNA damage, which disrupts intestinal organogenesis. This study reveals a mechanism for how cells with inactive DSB checkpoints can respond to DNA damage that persists into mitosis.
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Affiliation(s)
- Delisa E. Clay
- Department of Cell Biology, Duke University School of Medicine, Durham, NC
| | - Heidi S. Bretscher
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC
| | - Erin A. Jezuit
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC
| | - Korie B. Bush
- University Program in Genetics and Genomics, Duke University School of Medicine, Durham, NC
| | - Donald T. Fox
- Department of Cell Biology, Duke University School of Medicine, Durham, NC
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC
- University Program in Genetics and Genomics, Duke University School of Medicine, Durham, NC
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17
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Abstract
DNA double-strand breaks (DSBs) are cytotoxic lesions that threaten genome integrity and cell viability. Typically, cells repair DSBs by either nonhomologous end joining (NHEJ) or homologous recombination (HR). The relative use of these two pathways depends on many factors, including cell cycle stage and the nature of the DNA ends. A critical determinant of repair pathway selection is the initiation of 5'→3' nucleolytic degradation of DNA ends, a process referred to as DNA end resection. End resection is essential to create single-stranded DNA overhangs, which serve as the substrate for the Rad51 recombinase to initiate HR and are refractory to NHEJ repair. Here, we review recent insights into the mechanisms of end resection, how it is regulated, and the pathological consequences of its dysregulation.
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Affiliation(s)
- Petr Cejka
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500 Bellinzona, Switzerland; .,Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH) Zürich, 8093 Zürich, Switzerland
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA; .,Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY 10032, USA
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18
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Paulsen T, Malapati P, Shibata Y, Wilson B, Eki R, Benamar M, Abbas T, Dutta A. MicroDNA levels are dependent on MMEJ, repressed by c-NHEJ pathway, and stimulated by DNA damage. Nucleic Acids Res 2021; 49:11787-11799. [PMID: 34718766 PMCID: PMC8599734 DOI: 10.1093/nar/gkab984] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 10/05/2021] [Accepted: 10/27/2021] [Indexed: 12/23/2022] Open
Abstract
Extrachromosomal circular DNA (eccDNA) are present within all eukaryotic organisms and actively contribute to gene expression changes. MicroDNA (200-1000bp) are the most abundant type of eccDNA and can amplify tRNA, microRNA, and novel si-like RNA sequences. Due to the heterogeneity of microDNA and the limited technology to directly quantify circular DNA molecules, the specific DNA repair pathways that contribute to microDNA formation have not been fully elucidated. Using a sensitive and quantitative assay that quantifies eight known abundant microDNA, we report that microDNA levels are dependent on resection after double-strand DNA break (DSB) and repair by Microhomology Mediated End Joining (MMEJ). Further, repair of DSB without resection by canonical Non-Homologous End Joining (c-NHEJ) diminishes microDNA formation. MicroDNA levels are induced locally even by a single site-directed DSB, suggesting that excision of genomic DNA by two closely spaced DSB is not necessary for microDNA formation. Consistent with all this, microDNA levels accumulate as cells undergo replication in S-phase, when DNA breaks and repair are elevated, and microDNA levels are decreased if DNA synthesis is prevented. Thus, formation of microDNA occurs during the repair of endogenous or induced DNA breaks by resection-based DNA repair pathways.
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Affiliation(s)
- Teressa Paulsen
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.,Department of Oncology, University of Oxford, Oxford OX3 7DQ, UK
| | - Pumoli Malapati
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Yoshiyuki Shibata
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.,Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294-0024, USA
| | - Briana Wilson
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Rebeka Eki
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.,Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Mouadh Benamar
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.,Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Tarek Abbas
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.,Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Anindya Dutta
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.,Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294-0024, USA
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19
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Swan RL, Cowell IG, Austin CA. Mechanisms to repair stalled Topoisomerase II-DNA covalent complexes. Mol Pharmacol 2021; 101:24-32. [PMID: 34689119 DOI: 10.1124/molpharm.121.000374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/11/2021] [Indexed: 11/22/2022] Open
Abstract
DNA topoisomerases regulate the topological state of DNA, relaxing DNA supercoils and resolving catenanes and knots that result from biological processes such as transcription and replication. DNA topoisomerase II (TOP2) enzymes achieve this by binding DNA and introducing an enzyme-bridged DNA double-strand break (DSB) where each protomer of the dimeric enzyme is covalently attached to the 5' end of the cleaved DNA via an active site tyrosine phosphodiester linkage. The enzyme then passes a second DNA duplex though the DNA break, before religation and release of the enzyme. However, this activity is potentially hazardous to the cell, as failure to complete religation leads to persistent TOP2 protein-DNA covalent complexes which are cytotoxic. Indeed, this property of topoisomerase has been exploited in cancer therapy in the form of topoisomerase poisons which block the religation stage of the reaction cycle, leading to an accumulation of topoisomerase-DNA adducts. A number of parallel cellular processes have been identified that lead to removal of these covalent TOP2-DNA complexes facilitating repair of the resulting protein-free DSB by standard DNA repair pathways. These pathways presumably arose to repair spontaneous stalled or poisoned TOP2-DNA complexes, but understanding their mechanisms also has implications for cancer therapy, particularly resistance to anti-cancer TOP2 poisons and the genotoxic side effects of these drugs. Here we review recent progress in the understanding of the processing to TOP2 DNA covalent complexes., The basic components and mechanisms plus the additional layer of complexity posed by the post-translational modifications that modulate these pathways. Significance Statement Multiple pathways have been reported for removal and repair of TOP2-DNA covalent complexes to ensure the timely and efficient repair of TOP2-DNA covalent adducts to protect the genome. Post-translational modifications such as ubiquitination and SUMOylation are involved in the regulation of TOP2-DNA complex repair. Small molecule inhibitors of these post translational modifications may help to improve outcomes of TOP2 poison chemotherapy, for example by increasing TOP2 poison cytotoxicity and reducing genotoxicity, but this remains to be determined.
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Affiliation(s)
- Rebecca L Swan
- Biosciences Institute, Newcastle University, United Kingdom
| | - Ian G Cowell
- Institute for Cell and Molecular Biosciences, Newcastle University, United Kingdom
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20
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Chakraborty P, Hiom K. DHX9-dependent recruitment of BRCA1 to RNA promotes DNA end resection in homologous recombination. Nat Commun 2021; 12:4126. [PMID: 34226554 PMCID: PMC8257769 DOI: 10.1038/s41467-021-24341-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 06/07/2021] [Indexed: 01/08/2023] Open
Abstract
Double stranded DNA Breaks (DSB) that occur in highly transcribed regions of the genome are preferentially repaired by homologous recombination repair (HR). However, the mechanisms that link transcription with HR are unknown. Here we identify a critical role for DHX9, a RNA helicase involved in the processing of pre-mRNA during transcription, in the initiation of HR. Cells that are deficient in DHX9 are impaired in the recruitment of RPA and RAD51 to sites of DNA damage and fail to repair DSB by HR. Consequently, these cells are hypersensitive to treatment with agents such as camptothecin and Olaparib that block transcription and generate DSB that specifically require HR for their repair. We show that DHX9 plays a critical role in HR by promoting the recruitment of BRCA1 to RNA as part of the RNA Polymerase II transcription complex, where it facilitates the resection of DSB. Moreover, defects in DHX9 also lead to impaired ATR-mediated damage signalling and an inability to restart DNA replication at camptothecin-induced DSB. Together, our data reveal a previously unknown role for DHX9 in the DNA Damage Response that provides a critical link between RNA, RNA Pol II and the repair of DNA damage by homologous recombination. DHX9 is an RNA helicase involved in the processing of pre-mRNA during transcription. Here the authors reveal a role for DHX9 in the initiation of homologues recombination during the early steps of end-resection.
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Affiliation(s)
- Prasun Chakraborty
- Division of Cellular Medicine, Jacqui Wood Cancer Centre, School of Medicine, University of Dundee, Scotland, United Kingdom
| | - Kevin Hiom
- Division of Cellular Medicine, Jacqui Wood Cancer Centre, School of Medicine, University of Dundee, Scotland, United Kingdom.
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21
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Bossaert M, Pipier A, Riou JF, Noirot C, Nguyên LT, Serre RF, Bouchez O, Defrancq E, Calsou P, Britton S, Gomez D. Transcription-associated topoisomerase 2α (TOP2A) activity is a major effector of cytotoxicity induced by G-quadruplex ligands. eLife 2021; 10:65184. [PMID: 34180392 PMCID: PMC8279764 DOI: 10.7554/elife.65184] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 06/16/2021] [Indexed: 12/11/2022] Open
Abstract
G-quadruplexes (G4) are non-canonical DNA structures found in the genome of most species including human. Small molecules stabilizing these structures, called G4 ligands, have been identified and, for some of them, shown to induce cytotoxic DNA double-strand breaks. Through the use of an unbiased genetic approach, we identify here topoisomerase 2α (TOP2A) as a major effector of cytotoxicity induced by two clastogenic G4 ligands, pyridostatin and CX-5461, the latter molecule currently undergoing phase I/II clinical trials in oncology. We show that both TOP2 activity and transcription account for DNA break production following G4 ligand treatments. In contrast, clastogenic activity of these G4 ligands is countered by topoisomerase 1 (TOP1), which limits co-transcriptional G4 formation, and by factors promoting transcriptional elongation. Altogether our results support that clastogenic G4 ligands act as DNA structure-driven TOP2 poisons at transcribed regions bearing G4 structures.
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Affiliation(s)
- Madeleine Bossaert
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France.,Equipe Labellisée Ligue Contre le Cancer 2018, Toulouse, France
| | - Angélique Pipier
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France.,Equipe Labellisée Ligue Contre le Cancer 2018, Toulouse, France
| | - Jean-Francois Riou
- Structure et Instabilité des Génomes, Muséum National d'Histoire Naturelle, CNRS, INSERM, Paris, France
| | - Céline Noirot
- INRAE, UR 875, Unité de Mathématique et Informatique Appliquées, Genotoul Bioinfo, Castanet-Tolosan, France
| | - Linh-Trang Nguyên
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | | | - Olivier Bouchez
- INRAE, US 1426, GeT-PlaGe, Genotoul, Castanet-Tolosan, France
| | - Eric Defrancq
- Département de Chimie Moléculaire, UMR CNRS 5250, Université Grenoble Alpes, Grenoble, France
| | - Patrick Calsou
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France.,Equipe Labellisée Ligue Contre le Cancer 2018, Toulouse, France
| | - Sébastien Britton
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France.,Equipe Labellisée Ligue Contre le Cancer 2018, Toulouse, France
| | - Dennis Gomez
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France.,Equipe Labellisée Ligue Contre le Cancer 2018, Toulouse, France
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22
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Al-Mugotir M, Lovelace JJ, George J, Bessho M, Pal D, Struble L, Kolar C, Rana S, Natarajan A, Bessho T, Borgstahl GEO. Selective killing of homologous recombination-deficient cancer cell lines by inhibitors of the RPA:RAD52 protein-protein interaction. PLoS One 2021; 16:e0248941. [PMID: 33784323 DOI: 10.1371/journal.pone.0248941] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 03/09/2021] [Indexed: 12/29/2022] Open
Abstract
Synthetic lethality is a successful strategy employed to develop selective chemotherapeutics against cancer cells. Inactivation of RAD52 is synthetically lethal to homologous recombination (HR) deficient cancer cell lines. Replication protein A (RPA) recruits RAD52 to repair sites, and the formation of this protein-protein complex is critical for RAD52 activity. To discover small molecules that inhibit the RPA:RAD52 protein-protein interaction (PPI), we screened chemical libraries with our newly developed Fluorescence-based protein-protein Interaction Assay (FluorIA). Eleven compounds were identified, including FDA-approved drugs (quinacrine, mitoxantrone, and doxorubicin). The FluorIA was used to rank the compounds by their ability to inhibit the RPA:RAD52 PPI and showed mitoxantrone and doxorubicin to be the most effective. Initial studies using the three FDA-approved drugs showed selective killing of BRCA1-mutated breast cancer cells (HCC1937), BRCA2-mutated ovarian cancer cells (PE01), and BRCA1-mutated ovarian cancer cells (UWB1.289). It was noteworthy that selective killing was seen in cells known to be resistant to PARP inhibitors (HCC1937 and UWB1 SYr13). A cell-based double-strand break (DSB) repair assay indicated that mitoxantrone significantly suppressed RAD52-dependent single-strand annealing (SSA) and mitoxantrone treatment disrupted the RPA:RAD52 PPI in cells. Furthermore, mitoxantrone reduced radiation-induced foci-formation of RAD52 with no significant activity against RAD51 foci formation. The results indicate that the RPA:RAD52 PPI could be a therapeutic target for HR-deficient cancers. These data also suggest that RAD52 is one of the targets of mitoxantrone and related compounds.
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Affiliation(s)
- Mona Al-Mugotir
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Jeffrey J Lovelace
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Joseph George
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Mika Bessho
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Dhananjaya Pal
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Lucas Struble
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Carol Kolar
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Sandeep Rana
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Amarnath Natarajan
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Tadayoshi Bessho
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Gloria E O Borgstahl
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
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23
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Chandramouly G, Liao S, Rusanov T, Borisonnik N, Calbert ML, Kent T, Sullivan-Reed K, Vekariya U, Kashkina E, Skorski T, Yan H, Pomerantz RT. Polθ promotes the repair of 5'-DNA-protein crosslinks by microhomology-mediated end-joining. Cell Rep 2021; 34:108820. [PMID: 33691100 PMCID: PMC8565190 DOI: 10.1016/j.celrep.2021.108820] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 11/23/2020] [Accepted: 02/12/2021] [Indexed: 12/25/2022] Open
Abstract
DNA polymerase θ (Polθ) confers resistance to chemotherapy agents that cause DNA-protein crosslinks (DPCs) at double-strand breaks (DSBs), such as topoisomerase inhibitors. This suggests Polθ might facilitate DPC repair by microhomology-mediated end-joining (MMEJ). Here, we investigate Polθ repair of DSBs carrying DPCs by monitoring MMEJ in Xenopus egg extracts. MMEJ in extracts is dependent on Polθ, exhibits the MMEJ repair signature, and efficiently repairs 5' terminal DPCs independently of non-homologous end-joining and the replisome. We demonstrate that Polθ promotes the repair of 5' terminal DPCs in mammalian cells by using an MMEJ reporter and find that Polθ confers resistance to formaldehyde in addition to topoisomerase inhibitors. Dual deficiency in Polθ and tyrosyl-DNA phosphodiesterase 2 (TDP2) causes severe cellular sensitivity to etoposide, which demonstrates MMEJ as an independent DPC repair pathway. These studies recapitulate MMEJ in vitro and elucidate how Polθ confers resistance to etoposide.
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Affiliation(s)
- Gurushankar Chandramouly
- Thomas Jefferson University, Sidney Kimmel Cancer Center, Department of Biochemistry and Molecular Biology, Philadelphia, PA 19107, USA
| | - Shuren Liao
- Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Timur Rusanov
- Washington University School of Medicine, Department of Pathology & Immunology, St. Louis, MO 63110, USA
| | - Nikita Borisonnik
- Thomas Jefferson University, Sidney Kimmel Cancer Center, Department of Biochemistry and Molecular Biology, Philadelphia, PA 19107, USA
| | - Marissa L Calbert
- Thomas Jefferson University, Sidney Kimmel Cancer Center, Department of Biochemistry and Molecular Biology, Philadelphia, PA 19107, USA; Fels Cancer Institute for Personalized Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA
| | - Tatiana Kent
- Thomas Jefferson University, Sidney Kimmel Cancer Center, Department of Biochemistry and Molecular Biology, Philadelphia, PA 19107, USA
| | - Katherine Sullivan-Reed
- Fels Cancer Institute for Personalized Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA
| | - Umeshkumar Vekariya
- Fels Cancer Institute for Personalized Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA
| | - Ekaterina Kashkina
- Fels Cancer Institute for Personalized Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA
| | - Tomasz Skorski
- Fels Cancer Institute for Personalized Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA
| | - Hong Yan
- Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Richard T Pomerantz
- Thomas Jefferson University, Sidney Kimmel Cancer Center, Department of Biochemistry and Molecular Biology, Philadelphia, PA 19107, USA.
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24
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Zaksauskaite R, Thomas RC, van Eeden F, El-Khamisy SF. Tdp1 protects from topoisomerase 1-mediated chromosomal breaks in adult zebrafish but is dispensable during larval development. SCIENCE ADVANCES 2021; 7:eabc4165. [PMID: 33514542 PMCID: PMC7846158 DOI: 10.1126/sciadv.abc4165] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 12/14/2020] [Indexed: 06/12/2023]
Abstract
Deficiency in the DNA end-processing enzyme, tyrosyl-DNA phosphodiesterase 1 (TDP1), causes progressive neurodegeneration in humans. Here, we generated a tdp1 knockout zebrafish and confirmed the lack of TDP1 activity. In adulthood, homozygotes exhibit hypersensitivity to topoisomerase 1 (Top1) poisons and a very mild locomotion defect. Unexpectedly, embryonic tdp1 -/- zebrafish were not hypersensitive to Top1 poisons and did not exhibit increased Top1-DNA breaks. This is in contrast to the hypersensitivity of Tdp1-deficient vertebrate models reported to date. Tdp1 is dispensable in the zebrafish embryo with transcript levels down-regulated in response to Top1-DNA damage. In contrast, apex2 and ercc4 (xpf) transcripts were up-regulated. These findings identify the tdp1-/- zebrafish embryo as the first vertebrate model that does not require Tdp1 to protect from Top1-DNA damage and identify apex2 and ercc4 (xpf) as putative players fulfilling this role. It highlights the requirement of distinct DNA repair factors across the life span of vertebrates.
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Affiliation(s)
- Ringaile Zaksauskaite
- Healthy Lifespan Institute, Sheffield Institute for Neuroscience, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - Ruth C Thomas
- Healthy Lifespan Institute, Sheffield Institute for Neuroscience, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
- Bateson Centre, Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Freek van Eeden
- Healthy Lifespan Institute, Sheffield Institute for Neuroscience, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK.
- Bateson Centre, Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Sherif F El-Khamisy
- Healthy Lifespan Institute, Sheffield Institute for Neuroscience, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK.
- The Institute of Cancer Therapeutics, University of Bradford, Bradford BD7 1DP, UK
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25
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Ensminger M, Löbrich M. One end to rule them all: Non-homologous end-joining and homologous recombination at DNA double-strand breaks. Br J Radiol 2020; 93:20191054. [PMID: 32105514 PMCID: PMC8519636 DOI: 10.1259/bjr.20191054] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Double-strand breaks (DSBs) represent the most severe type of DNA damage since they can lead to genomic rearrangements, events that can initiate and promote tumorigenic processes. DSBs arise from various exogenous agents that induce two single-strand breaks at opposite locations in the DNA double helix. Such two-ended DSBs are repaired in mammalian cells by one of two conceptually different processes, non-homologous end-joining (NHEJ) and homologous recombination (HR). NHEJ has the potential to form rearrangements while HR is believed to be error-free since it uses a homologous template for repair. DSBs can also arise from single-stranded DNA lesions if they lead to replication fork collapse. Such DSBs, however, have only one end and are repaired by HR and not by NHEJ. In fact, the majority of spontaneously arising DSBs are one-ended and HR has likely evolved to repair one-ended DSBs. HR of such DSBs demands the engagement of a second break end that is generated by an approaching replication fork. This HR process can cause rearrangements if a homologous template other than the sister chromatid is used. Thus, both NHEJ and HR have the potential to form rearrangements and the proper choice between them is governed by various factors, including cell cycle phase and genomic location of the lesion. We propose that the specific requirements for repairing one-ended DSBs have shaped HR in a way which makes NHEJ the better choice for the repair of some but not all two-ended DSBs.
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Affiliation(s)
- Michael Ensminger
- Radiation Biology and DNA Repair, Technical University of Darmstadt, 64287 Darmstadt, Germany
| | - Markus Löbrich
- Radiation Biology and DNA Repair, Technical University of Darmstadt, 64287 Darmstadt, Germany
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26
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Wikiniyadhanee R, Lerksuthirat T, Stitchantrakul W, Chitphuk S, Sura T, Dejsuphong D. TRIM29 is required for efficient recruitment of 53BP1 in response to DNA double-strand breaks in vertebrate cells. FEBS Open Bio 2020; 10:2055-2071. [PMID: 33017104 PMCID: PMC7530400 DOI: 10.1002/2211-5463.12954] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 07/18/2020] [Accepted: 08/14/2020] [Indexed: 12/17/2022] Open
Abstract
Tripartite motif‐containing protein 29 (TRIM29) is involved in DNA double‐strand break (DSB) repair. However, the specific roles of TRIM29 in DNA repair are not clearly understood. To investigate the involvement of TRIM29 in DNA DSB repair, we disrupted TRIM29 in DT40 cells by gene targeting with homologous recombination (HR). The roles of TRIM29 were investigated by clonogenic survival assays and immunofluorescence analyses. TRIM29 triallelic knockout (TRIM29−/−/−/+) cells were sensitive to etoposide, but resistant to camptothecin. Foci formation assays to assess DNA repair activities showed that the dissociation of etoposide‐induced phosphorylated H2A histone family member X (ɣ‐H2AX) foci was retained in TRIM29−/−/−/+ cells, and the formation of etoposide‐induced tumor suppressor p53‐binding protein 1 (53BP1) foci in TRIM29−/−/−/+ cells was slower compared with wild‐type (WT) cells. Interestingly, the kinetics of camptothecin‐induced RAD51 foci formation of TRIM29−/−/−/+ cells was higher than that of WT cells. These results indicate that TRIM29 is required for efficient recruitment of 53BP1 to facilitate the nonhomologous end‐joining (NHEJ) pathway and thereby suppress the HR pathway in response to DNA DSBs. TRIM29 regulates the choice of DNA DSB repair pathway by facilitating 53BP1 accumulation to promote NHEJ and may have potential for development into a therapeutic target to sensitize refractory cancers or as biomarker of personalized therapies.
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Affiliation(s)
- Rakkreat Wikiniyadhanee
- Section for Translational Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Tassanee Lerksuthirat
- Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Wasana Stitchantrakul
- Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Sermsiri Chitphuk
- Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Thanyachai Sura
- Department of Internal Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Donniphat Dejsuphong
- Section for Translational Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
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27
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Alonso-de Vega I, Paz-Cabrera MC, Rother MB, Wiegant WW, Checa-Rodríguez C, Hernández-Fernaud JR, Huertas P, Freire R, van Attikum H, Smits VAJ. PHF2 regulates homology-directed DNA repair by controlling the resection of DNA double strand breaks. Nucleic Acids Res 2020; 48:4915-4927. [PMID: 32232336 PMCID: PMC7229830 DOI: 10.1093/nar/gkaa196] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 03/12/2020] [Accepted: 03/27/2020] [Indexed: 12/17/2022] Open
Abstract
Post-translational histone modifications and chromatin remodelling play a critical role controlling the integrity of the genome. Here, we identify histone lysine demethylase PHF2 as a novel regulator of the DNA damage response by regulating DNA damage-induced focus formation of 53BP1 and BRCA1, critical factors in the pathway choice for DNA double strand break repair. PHF2 knockdown leads to impaired BRCA1 focus formation and delays the resolution of 53BP1 foci. Moreover, irradiation-induced RPA phosphorylation and focus formation, as well as localization of CtIP, required for DNA end resection, to sites of DNA lesions are affected by depletion of PHF2. These results are indicative of a defective resection of double strand breaks and thereby an impaired homologous recombination upon PHF2 depletion. In accordance with these data, Rad51 focus formation and homology-directed double strand break repair is inhibited in cells depleted for PHF2. Importantly, we demonstrate that PHF2 knockdown decreases CtIP and BRCA1 protein and mRNA levels, an effect that is dependent on the demethylase activity of PHF2. Furthermore, PHF2-depleted cells display genome instability and are mildly sensitive to the inhibition of PARP. Together these results demonstrate that PHF2 promotes DNA repair by homologous recombination by controlling CtIP-dependent resection of double strand breaks.
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Affiliation(s)
| | | | - Magdalena B Rother
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Wouter W Wiegant
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | | | | | - Pablo Huertas
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Sevilla, Spain
| | - Raimundo Freire
- Unidad de Investigación, Hospital Universitario de Canarias, Tenerife, Spain.,Instituto de Tecnologías Biomédicas, Universidad de La Laguna, Tenerife, Spain.,Universidad Fernando Pessoa Canarias, Las Palmas de Gran Canaria, Spain
| | - Haico van Attikum
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Veronique A J Smits
- Unidad de Investigación, Hospital Universitario de Canarias, Tenerife, Spain.,Instituto de Tecnologías Biomédicas, Universidad de La Laguna, Tenerife, Spain.,Universidad Fernando Pessoa Canarias, Las Palmas de Gran Canaria, Spain
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28
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Swan RL, Poh LLK, Cowell IG, Austin CA. Small Molecule Inhibitors Confirm Ubiquitin-Dependent Removal of TOP2-DNA Covalent Complexes. Mol Pharmacol 2020; 98:222-233. [PMID: 32587095 PMCID: PMC7416847 DOI: 10.1124/mol.119.118893] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 06/09/2020] [Indexed: 12/13/2022] Open
Abstract
DNA topoisomerase II (TOP2) is required for the unwinding and decatenation of DNA through the induction of an enzyme-linked double-strand break (DSB) in one DNA molecule and passage of another intact DNA duplex through the break. Anticancer drugs targeting TOP2 (TOP2 poisons) prevent religation of the DSB and stabilize a normally transient intermediate of the TOP2 reaction mechanism called the TOP2-DNA covalent complex. Subsequently, TOP2 remains covalently bound to each end of the enzyme-bridged DSB, which cannot be repaired until TOP2 is removed from the DNA. One removal mechanism involves the proteasomal degradation of the TOP2 protein, leading to the liberation of a protein-free DSB. Proteasomal degradation is often regulated by protein ubiquitination, and here we show that inhibition of ubiquitin-activating enzymes reduces the processing of TOP2A- and TOP2B-DNA complexes. Depletion or inhibition of ubiquitin-activating enzymes indicated that ubiquitination was required for the liberation of etoposide-induced protein-free DSBs and is therefore an important layer of regulation in the repair of TOP2 poison-induced DNA damage. TOP2-DNA complexes stabilized by etoposide were shown to be conjugated to ubiquitin, and this was reduced by inhibition or depletion of ubiquitin-activating enzymes. SIGNIFICANCE STATEMENT: There is currently great clinical interest in the ubiquitin-proteasome system and ongoing development of specific inhibitors. The results in this paper show that the therapeutic cytotoxicity of DNA topoisomerase II (TOP2) poisons can be enhanced through combination therapy with ubiquitin-activating enzyme inhibitors or by specific inhibition of the BMI/RING1A ubiquitin ligase, which would lead to increased cellular accumulation or persistence of TOP2-DNA complexes.
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Affiliation(s)
- Rebecca L Swan
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Luke L K Poh
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Ian G Cowell
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Caroline A Austin
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
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29
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Howard SM, Ceppi I, Anand R, Geiger R, Cejka P. The internal region of CtIP negatively regulates DNA end resection. Nucleic Acids Res 2020; 48:5485-5498. [PMID: 32347940 PMCID: PMC7261161 DOI: 10.1093/nar/gkaa273] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 04/05/2020] [Accepted: 04/14/2020] [Indexed: 12/16/2022] Open
Abstract
DNA double-strand breaks are repaired by end-joining or homologous recombination. A key-committing step of recombination is DNA end resection. In resection, phosphorylated CtIP first promotes the endonuclease of MRE11-RAD50-NBS1 (MRN). Subsequently, CtIP also stimulates the WRN/BLM-DNA2 pathway, coordinating thus both short and long-range resection. The structure of CtIP differs from its orthologues in yeast, as it contains a large internal unstructured region. Here, we conducted a domain analysis of CtIP to define the function of the internal region in DNA end resection. We found that residues 350-600 were entirely dispensable for resection in vitro. A mutant lacking these residues was unexpectedly more efficient than full-length CtIP in DNA end resection and homologous recombination in vivo, and consequently conferred resistance to lesions induced by the topoisomerase poison camptothecin, which require high MRN-CtIP-dependent resection activity for repair. This suggested that the internal CtIP region, further mapped to residues 550-600, may mediate a negative regulatory function to prevent over resection in vivo. The CtIP internal deletion mutant exhibited sensitivity to other DNA-damaging drugs, showing that upregulated resection may be instead toxic under different conditions. These experiments together identify a region within the central CtIP domain that negatively regulates DNA end resection.
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Affiliation(s)
- Sean Michael Howard
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona, Switzerland
| | - Ilaria Ceppi
- 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
| | - Roopesh Anand
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona, Switzerland
| | - Roger Geiger
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona, 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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30
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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: 48] [Impact Index Per Article: 12.0] [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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31
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A role of the 53BP1 protein in genome protection: structural and functional characteristics of 53BP1-dependent DNA repair. Aging (Albany NY) 2020; 11:2488-2511. [PMID: 30996128 PMCID: PMC6519998 DOI: 10.18632/aging.101917] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Accepted: 04/10/2019] [Indexed: 12/13/2022]
Abstract
Nuclear architecture plays a significant role in DNA repair mechanisms. It is evident that proteins involved in DNA repair are compartmentalized in not only spontaneously occurring DNA lesions or ionizing radiation-induced foci (IRIF), but a specific clustering of these proteins can also be observed within the whole cell nucleus. For example, 53BP1-positive and BRCA1-positive DNA repair foci decorate chromocenters and can appear close to nuclear speckles. Both 53BP1 and BRCA1 are well-described factors that play an essential role in double-strand break (DSB) repair. These proteins are members of two protein complexes: 53BP1-RIF1-PTIP and BRCA1-CtIP, which make a “decision” determining whether canonical nonhomologous end joining (NHEJ) or homology-directed repair (HDR) is activated. It is generally accepted that 53BP1 mediates the NHEJ mechanism, while HDR is activated via a BRCA1-dependent signaling pathway. Interestingly, the 53BP1 protein appears relatively quickly at DSB sites, while BRCA1 is functional at later stages of DNA repair, as soon as the Mre11-Rad50-Nbs1 complex is recruited to the DNA lesions. A function of the 53BP1 protein is also linked to a specific histone signature, including phosphorylation of histone H2AX (γH2AX) or methylation of histone H4 at the lysine 20 position (H4K20me); therefore, we also discuss an epigenetic landscape of 53BP1-positive DNA lesions.
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32
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Tisi R, Vertemara J, Zampella G, Longhese MP. Functional and structural insights into the MRX/MRN complex, a key player in recognition and repair of DNA double-strand breaks. Comput Struct Biotechnol J 2020; 18:1137-1152. [PMID: 32489527 PMCID: PMC7260605 DOI: 10.1016/j.csbj.2020.05.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 05/07/2020] [Accepted: 05/09/2020] [Indexed: 01/20/2023] Open
Abstract
Chromosomal DNA double-strand breaks (DSBs) are potentially lethal DNA lesions that pose a significant threat to genome stability and therefore need to be repaired to preserve genome integrity. Eukaryotic cells possess two main mechanisms for repairing DSBs: non-homologous end-joining (NHEJ) and homologous recombination (HR). HR requires that the 5' terminated strands at both DNA ends are nucleolytically degraded by a concerted action of nucleases in a process termed DNA-end resection. This degradation leads to the formation of 3'-ended single-stranded DNA (ssDNA) ends that are essential to use homologous DNA sequences for repair. The evolutionarily conserved Mre11-Rad50-Xrs2/NBS1 complex (MRX/MRN) has enzymatic and structural activities to initiate DSB resection and to maintain the DSB ends tethered to each other for their repair. Furthermore, it is required to recruit and activate the protein kinase Tel1/ATM, which plays a key role in DSB signaling. All these functions depend on ATP-regulated DNA binding and nucleolytic activities of the complex. Several structures have been obtained in recent years for Mre11 and Rad50 subunits from archaea, and a few from the bacterial and eukaryotic orthologs. Nevertheless, the mechanism of activation of this protein complex is yet to be fully elucidated. In this review, we focused on recent biophysical and structural insights on the MRX complex and their interplay.
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Affiliation(s)
- Renata Tisi
- Dipartimento di Biotecnologie and Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
| | - Jacopo Vertemara
- Dipartimento di Biotecnologie and Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
| | - Giuseppe Zampella
- Dipartimento di Biotecnologie and Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie and Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
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33
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Mei C, Lei L, Tan LM, Xu XJ, He BM, Luo C, Yin JY, Li X, Zhang W, Zhou HH, Liu ZQ. The role of single strand break repair pathways in cellular responses to camptothecin induced DNA damage. Biomed Pharmacother 2020; 125:109875. [DOI: 10.1016/j.biopha.2020.109875] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/24/2019] [Accepted: 01/06/2020] [Indexed: 12/12/2022] Open
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34
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Akagawa R, Trinh HT, Saha LK, Tsuda M, Hirota K, Yamada S, Shibata A, Kanemaki MT, Nakada S, Takeda S, Sasanuma H. UBC13-Mediated Ubiquitin Signaling Promotes Removal of Blocking Adducts from DNA Double-Strand Breaks. iScience 2020; 23:101027. [PMID: 32283528 PMCID: PMC7155233 DOI: 10.1016/j.isci.2020.101027] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 02/22/2020] [Accepted: 03/26/2020] [Indexed: 12/25/2022] Open
Abstract
Chemical modifications and adducts at DNA double-strand break (DSB) ends must be cleaned before re-joining by non-homologous end-joining (NHEJ). MRE11 nuclease is essential for efficient removal of Topoisomerase II (TOP2)-DNA adducts from TOP2 poison-induced DSBs. However, mechanisms in MRE11 recruitment to DSB sites in G1 phase remain poorly understood. Here, we report that TOP2-DNA adducts are expeditiously removed through UBC13-mediated polyubiquitination, which promotes DSB resection in G2 phase. We found that this ubiquitin signaling is required for efficient recruitment of MRE11 onto DSB sites in G1 by facilitating localization of RAP80 and BRCA1 to DSB sites and complex formation between BRCA1 and MRE11 at DSB sites. UBC13 and MRE11 are dispensable for restriction-enzyme-induced "clean" DSBs repair but responsible for over 50% and 70% of NHEJ-dependent repair of γ-ray-induced "dirty" DSBs, respectively. In conclusion, ubiquitin signaling promotes nucleolytic removal of DSB blocking adducts by MRE11 before NHEJ.
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Affiliation(s)
- Remi Akagawa
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hai Thanh Trinh
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Liton Kumar Saha
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Masataka Tsuda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kouji Hirota
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Hachioji-shi, Tokyo 192-0397, Japan
| | - Shintaro Yamada
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan; Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Atsushi Shibata
- Signal Transduction Program, Gunma University Initiative for Advanced Research (GIAR), Gunma University, Maebashi, Gunma 371-8511, Japan
| | - Masato T Kanemaki
- National Institute of Genetics, Research Organization of Information and Systems (ROIS), and Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - Shinichiro Nakada
- Department of Bioregulation and Cellular Response, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Shunichi Takeda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
| | - Hiroyuki Sasanuma
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
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35
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Sun Y, Saha S, Wang W, Saha LK, Huang SYN, Pommier Y. Excision repair of topoisomerase DNA-protein crosslinks (TOP-DPC). DNA Repair (Amst) 2020; 89:102837. [PMID: 32200233 DOI: 10.1016/j.dnarep.2020.102837] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/22/2020] [Accepted: 02/25/2020] [Indexed: 12/13/2022]
Abstract
Topoisomerases are essential enzymes solving DNA topological problems such as supercoils, knots and catenanes that arise from replication, transcription, chromatin remodeling and other nucleic acid metabolic processes. They are also the targets of widely used anticancer drugs (e.g. topotecan, irinotecan, enhertu, etoposide, doxorubicin, mitoxantrone) and fluoroquinolone antibiotics (e.g. ciprofloxacin and levofloxacin). Topoisomerases manipulate DNA topology by cleaving one DNA strand (TOP1 and TOP3 enzymes) or both in concert (TOP2 enzymes) through the formation of transient enzyme-DNA cleavage complexes (TOPcc) with phosphotyrosyl linkages between DNA ends and the catalytic tyrosyl residue of the enzymes. Failure in the self-resealing of TOPcc results in persistent TOPcc (which we refer it to as topoisomerase DNA-protein crosslinks (TOP-DPC)) that threaten genome integrity and lead to cancers and neurodegenerative diseases. The cell prevents the accumulation of topoisomerase-mediated DNA damage by excising TOP-DPC and ligating the associated breaks using multiple pathways conserved in eukaryotes. Tyrosyl-DNA phosphodiesterases (TDP1 and TDP2) cleave the tyrosyl-DNA bonds whereas structure-specific endonucleases such as Mre11 and XPF (Rad1) incise the DNA phosphodiester backbone to remove the TOP-DPC along with the adjacent DNA segment. The proteasome and metalloproteases of the WSS1/Spartan family typify proteolytic repair pathways that debulk TOP-DPC to make the peptide-DNA bonds accessible to the TDPs and endonucleases. The purpose of this review is to summarize our current understanding of how the cell excises TOP-DPC and why, when and where the cell recruits one specific mechanism for repairing topoisomerase-mediated DNA damage, acquiring resistance to therapeutic topoisomerase inhibitors and avoiding genomic instability, cancers and neurodegenerative diseases.
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Affiliation(s)
- Yilun Sun
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Sourav Saha
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Wenjie Wang
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Liton Kumar Saha
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Shar-Yin Naomi Huang
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Yves Pommier
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States.
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36
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Deshpande RA, Myler LR, Soniat MM, Makharashvili N, Lee L, Lees-Miller SP, Finkelstein IJ, Paull TT. DNA-dependent protein kinase promotes DNA end processing by MRN and CtIP. SCIENCE ADVANCES 2020; 6:eaay0922. [PMID: 31934630 PMCID: PMC6949041 DOI: 10.1126/sciadv.aay0922] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Accepted: 11/12/2019] [Indexed: 06/10/2023]
Abstract
The repair of DNA double-strand breaks occurs through nonhomologous end joining or homologous recombination in vertebrate cells-a choice that is thought to be decided by a competition between DNA-dependent protein kinase (DNA-PK) and the Mre11/Rad50/Nbs1 (MRN) complex but is not well understood. Using ensemble biochemistry and single-molecule approaches, here, we show that the MRN complex is dependent on DNA-PK and phosphorylated CtIP to perform efficient processing and resection of DNA ends in physiological conditions, thus eliminating the competition model. Endonucleolytic removal of DNA-PK-bound DNA ends is also observed at double-strand break sites in human cells. The involvement of DNA-PK in MRN-mediated end processing promotes an efficient and sequential transition from nonhomologous end joining to homologous recombination by facilitating DNA-PK removal.
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Affiliation(s)
- Rajashree A. Deshpande
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Logan R. Myler
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, NY 10065, USA
| | - Michael M. Soniat
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Nodar Makharashvili
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Linda Lee
- Department of Biochemistry and Molecular Biology, University of Calgary, Alberta T2N 1N4, Canada
| | - Susan P. Lees-Miller
- Department of Biochemistry and Molecular Biology, University of Calgary, Alberta T2N 1N4, Canada
| | - Ilya J. Finkelstein
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Tanya T. Paull
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
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37
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Tsuda M, Kitamasu K, Hosokawa S, Nakano T, Ide H. Repair of trapped topoisomerase II covalent cleavage complexes: Novel proteasome-independent mechanisms. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2019; 39:170-184. [PMID: 31608820 DOI: 10.1080/15257770.2019.1674332] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Topoisomerase II (TOP2) resolves topologically entwined duplex DNA. It generates a transient DNA double-strand break intermediate, known as TOP2 cleavage complex (TOP2cc) that contains a covalent link between TOP2 and the 5'-terminus of the incised DNA duplex. Etoposide, a frontline anticancer drug, freezes the intermediate and forms irreversible TOP2ccs. Tyrosyl-DNA phosphodiesterase 2 (TDP2) is thought to repair irreversible TOP2ccs by hydrolyzing the phosphodiester bond between TOP2 and DNA after the proteasomal degradation of trapped TOP2ccs. However, the functional cooperation between TOP2 and proteasome in the repair of trapped TOP2ccs in vivo remains unknown. In this study, we analyze the repair of etoposide-induced TOP2ccs in wild-type and TDP2-deficient (TDP2-/-) TK6 cells in the absence and presence of MG132, a potent proteasome inhibitor. The results suggested that TOP2ccs were repaired by proteasome-dependent and proteasome-independent pathways. Both proteasome-dependent and proteasome-independent pathways were further subdivided into TDP2-dependent and TDP2-independent pathways, indicating that four pathways operate in the repair of TOP2ccs. In cell survival assays, MG132 increased the etoposide sensitivity of TDP2-/- cells, supporting the TDP2-independent and proteasome-dependent pathway among these multiple repair pathways. We also demonstrated that TDP2 released TOP2 from DNA that contained etoposide-induced TOP2cc without proteolytic degradation in vitro. Taken together, the present findings uncover novel proteasome-independent mechanisms for the repair of TOP2ccs.
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Affiliation(s)
- Masataka Tsuda
- Program of Mathematical and Life Sciences, Department of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Kaito Kitamasu
- Program of Mathematical and Life Sciences, Department of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Seiji Hosokawa
- Program of Mathematical and Life Sciences, Department of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Toshiaki Nakano
- DNA Damage Chemistry Research Group, Institute for Quantum Life Science, National Institutes of Quantum and Radiological Science and Technology, Kizugawa-shi, Japan
| | - Hiroshi Ide
- Program of Mathematical and Life Sciences, Department of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
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38
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Mohiuddin M, Rahman MM, Sale JE, Pearson CE. CtIP-BRCA1 complex and MRE11 maintain replication forks in the presence of chain terminating nucleoside analogs. Nucleic Acids Res 2019; 47:2966-2980. [PMID: 30657944 PMCID: PMC6451104 DOI: 10.1093/nar/gkz009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 12/30/2018] [Accepted: 01/09/2019] [Indexed: 12/20/2022] Open
Abstract
Chain-terminating nucleoside analogs (CTNAs), which cannot be extended by DNA polymerases, are widely used as antivirals or anti-cancer agents, and can induce cell death. Processing of blocked DNA ends, like camptothecin-induced trapped-topoisomerase I, can be mediated by TDP1, BRCA1, CtIP and MRE11. Here, we investigated whether the CtIP-BRCA1 complex and MRE11 also contribute to cellular tolerance to CTNAs, including 2',3'-dideoxycytidine (ddC), cytarabine (ara-C) and zidovudine (Azidothymidine, AZT). We show that BRCA1-/-, CtIPS332A/-/- and nuclease-dead MRE11D20A/- mutants display increased sensitivity to CTNAs, accumulate more DNA damage (chromosomal breaks, γ-H2AX and neutral comets) when treated with CTNAs and exhibit significant delays in replication fork progression during exposure to CTNAs. Moreover, BRCA1-/-, CtIPS332A/-/- and nuclease-dead MRE11D20A/- mutants failed to resume DNA replication in response to CTNAs, whereas control and CtIP+/-/- cells experienced extensive recovery of DNA replication. In summary, we provide clear evidence that MRE11 and the collaborative action of BRCA1 and CtIP play a critical role in the nuclease-dependent removal of incorporated ddC from replicating genomic DNA. We propose that BRCA1-CTIP and MRE11 prepare nascent DNA ends, blocked from synthesis by CTNAs, for further repair.
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Affiliation(s)
- Mohiuddin Mohiuddin
- Program of Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Md Maminur Rahman
- Department of Radiation Genetics, Kyoto University Graduate School of Medicine, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Julian E Sale
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | - Christopher E Pearson
- Program of Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.,The Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
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39
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Abstract
The repair of DNA double-strand breaks occurs through a series of defined steps that are evolutionarily conserved and well-understood in most experimental organisms. However, it is becoming increasingly clear that repair does not occur in isolation from other DNA transactions. Transcription of DNA produces topological changes, RNA species, and RNA-dependent protein complexes that can dramatically influence the efficiency and outcomes of DNA double-strand break repair. The transcription-associated history of several double-strand break repair factors is reviewed here, with an emphasis on their roles in regulating R-loops and the emerging role of R-loops in coordination of repair events. Evidence for nucleolytic processing of R-loops is also discussed, as well as the molecular tools commonly used to measure RNA-DNA hybrids in cells.
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Affiliation(s)
- Tanya T Paull
- The Department of Molecular Biosciences and the Howard Hughes Medical Institute, The University of Texas at Austin, Austin, TX, USA
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40
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Caron MC, Sharma AK, O'Sullivan J, Myler LR, Ferreira MT, Rodrigue A, Coulombe Y, Ethier C, Gagné JP, Langelier MF, Pascal JM, Finkelstein IJ, Hendzel MJ, Poirier GG, Masson JY. Poly(ADP-ribose) polymerase-1 antagonizes DNA resection at double-strand breaks. Nat Commun 2019; 10:2954. [PMID: 31273204 PMCID: PMC6609622 DOI: 10.1038/s41467-019-10741-9] [Citation(s) in RCA: 107] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 05/29/2019] [Indexed: 12/20/2022] Open
Abstract
PARP-1 is rapidly recruited and activated by DNA double-strand breaks (DSBs). Upon activation, PARP-1 synthesizes a structurally complex polymer composed of ADP-ribose units that facilitates local chromatin relaxation and the recruitment of DNA repair factors. Here, we identify a function for PARP-1 in DNA DSB resection. Remarkably, inhibition of PARP-1 leads to hyperresected DNA DSBs. We show that loss of PARP-1 and hyperresection are associated with loss of Ku, 53BP1 and RIF1 resection inhibitors from the break site. DNA curtains analysis show that EXO1-mediated resection is blocked by PARP-1. Furthermore, PARP-1 abrogation leads to increased DNA resection tracks and an increase of homologous recombination in cellulo. Our results, therefore, place PARP-1 activation as a critical early event for DNA DSB repair activation and regulation of resection. Hence, our work has direct implications for the clinical use and effectiveness of PARP inhibition, which is prescribed for the treatment of various malignancies. Poly(ADP-ribose) polymerase-1 (PARP-1) facilitates local chromatin relaxation and the recruitment of DNA repair factors at double strand breaks site (DSBs). Here the authors reveal that PARP-1 acts as a critical regulator of DNA end resection of DSBs.
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Affiliation(s)
- Marie-Christine Caron
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Division, 9 McMahon, Québec City, QC, G1R 3S3, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, QC, G1V 0A6, Canada
| | - Ajit K Sharma
- Department of Oncology, Faculty of Medicine and Dentistry, University of Alberta, 11560 University Avenue, Edmonton, AL, T6G 1Z2, Canada
| | - Julia O'Sullivan
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Division, 9 McMahon, Québec City, QC, G1R 3S3, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, QC, G1V 0A6, Canada
| | - Logan R Myler
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
| | - Maria Tedim Ferreira
- Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, QC, G1V 0A6, Canada.,CHU de Québec Research Center, CHUL Pavilion, Oncology Division, 2705 Boulevard Laurier, Québec City, QC, G1V 4G2, Canada
| | - Amélie Rodrigue
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Division, 9 McMahon, Québec City, QC, G1R 3S3, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, QC, G1V 0A6, Canada
| | - Yan Coulombe
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Division, 9 McMahon, Québec City, QC, G1R 3S3, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, QC, G1V 0A6, Canada
| | - Chantal Ethier
- Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, QC, G1V 0A6, Canada.,CHU de Québec Research Center, CHUL Pavilion, Oncology Division, 2705 Boulevard Laurier, Québec City, QC, G1V 4G2, Canada
| | - Jean-Philippe Gagné
- Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, QC, G1V 0A6, Canada.,CHU de Québec Research Center, CHUL Pavilion, Oncology Division, 2705 Boulevard Laurier, Québec City, QC, G1V 4G2, Canada
| | - Marie-France Langelier
- Biochemistry and Molecular Medicine, Université de Montréal, 2900 Boulevard Edouard-Montpetit, Pavillon Roger-Gaudry, Montréal, QC, H3T 1J4, Canada
| | - John M Pascal
- Biochemistry and Molecular Medicine, Université de Montréal, 2900 Boulevard Edouard-Montpetit, Pavillon Roger-Gaudry, Montréal, QC, H3T 1J4, Canada
| | - Ilya J Finkelstein
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
| | - Michael J Hendzel
- Department of Oncology, Faculty of Medicine and Dentistry, University of Alberta, 11560 University Avenue, Edmonton, AL, T6G 1Z2, Canada.
| | - Guy G Poirier
- Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, QC, G1V 0A6, Canada. .,CHU de Québec Research Center, CHUL Pavilion, Oncology Division, 2705 Boulevard Laurier, Québec City, QC, G1V 4G2, Canada.
| | - Jean-Yves Masson
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Division, 9 McMahon, Québec City, QC, G1R 3S3, Canada. .,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, QC, G1V 0A6, Canada.
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41
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The dynamics and regulation of chromatin remodeling during spermiogenesis. Gene 2019; 706:201-210. [DOI: 10.1016/j.gene.2019.05.027] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/08/2019] [Accepted: 05/10/2019] [Indexed: 01/06/2023]
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42
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Liu X, Wang XS, Lee BJ, Wu-Baer FK, Lin X, Shao Z, Estes VM, Gautier J, Baer R, Zha S. CtIP is essential for early B cell proliferation and development in mice. J Exp Med 2019; 216:1648-1663. [PMID: 31097467 PMCID: PMC6605744 DOI: 10.1084/jem.20181139] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Revised: 09/10/2018] [Accepted: 04/24/2019] [Indexed: 11/08/2022] Open
Abstract
B cell development requires efficient proliferation and successful assembly and modifications of the immunoglobulin gene products. CtIP is an essential gene implicated in end resection and DNA repair. Here, we show that CtIP is essential for early B cell development but dispensable in naive B cells. CtIP loss is well tolerated in G1-arrested B cells and during V(D)J recombination, but in proliferating B cells, CtIP loss leads to a progressive cell death characterized by ATM hyperactivation, G2/M arrest, genomic instability, and 53BP1 nuclear body formation, indicating that the essential role of CtIP during proliferation underscores its stage-specific requirement in B cells. B cell proliferation requires phosphorylation of CtIP at T847 presumably by CDK, but not its interaction with CtBP or Rb or its nuclease activity. CtIP phosphorylation by ATM/ATR at T859 (T855 in mice) promotes end resection in G1-arrested cells but is dispensable for B cell development and class switch recombination, suggesting distinct roles for T859 and T847 phosphorylation in B cell development.
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Affiliation(s)
- Xiangyu Liu
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Shenzhen University Carson Cancer Center, Department of Biochemistry and Molecular Biology, School of Medicine, Shenzhen University, Shenzhen, China
| | - Xiaobin S Wang
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
- Pathobiology and Human Disease Graduate Program, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
| | - Brian J Lee
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
| | - Foon K Wu-Baer
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
| | - Xiaohui Lin
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
| | - Zhengping Shao
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
| | - Verna M Estes
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
| | - Jean Gautier
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
| | - Richard Baer
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
| | - Shan Zha
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
- Division of Pediatric Oncology, Hematology and Stem Cell Transplantation, Department of Pediatrics, Vagelos College of Physicians & Surgeons, Columbia University, New York, NY
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43
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Lamarche BJ, Orazio NI, Goben B, Meisenhelder J, You Z, Weitzman MD, Hunter T. Repair of protein-linked DNA double strand breaks: Using the adenovirus genome as a model substrate in cell-based assays. DNA Repair (Amst) 2018; 74:80-90. [PMID: 30583959 DOI: 10.1016/j.dnarep.2018.12.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 12/07/2018] [Accepted: 12/07/2018] [Indexed: 11/29/2022]
Abstract
The DNA double strand breaks (DSBs) created during meiotic recombination and during some types of chemotherapy contain protein covalently attached to their 5' termini. Removal of the end-blocking protein is a prerequisite to DSB processing by non-homologous end-joining or homologous recombination. One mechanism for removing the protein involves CtIP-stimulated Mre11-catalyzed nicking of the protein-linked strand distal to the DSB terminus, releasing the end-blocking protein while it remains covalently attached to an oligonucleotide. Much of what is known about this repair process has recently been deciphered through in vitro reconstitution studies. We present here a novel model system based on adenovirus (Ad), which contains the Ad terminal protein covalently linked to the 5' terminus of its dsDNA genome, for studying the repair of 5' protein-linked DSBs in vivo. It was previously shown that the genome of Ad mutants that lack early region 4 (E4) can be joined into concatemers in vivo, suggesting that the Ad terminal protein had been removed from the genome termini prior to ligation. Here we show that during infection with the E4-deleted Ad mutant dl1004, the Ad terminal protein is removed in a manner that recapitulates removal of end-blocking proteins from cellular DSBs. In addition to displaying a dependence on CtIP, and Mre11 acting as the endonuclease, the protein-linked oligonucleotides that are released from the viral genome are similar in size to the oligos that remain attached to Spo11 and Top2 after they are removed from the 5' termini of DSBs during meiotic recombination and etoposide chemotherapy, respectively. The single nucleotide resolution that is possible with this assay, combined with the single sequence context in which the lesion is presented, make it a useful tool for further refining our mechanistic understanding of how blocking proteins are removed from the 5' termini of DSBs.
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Affiliation(s)
- Brandon J Lamarche
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, California, 92037, USA; Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California, 92037, USA
| | - Nicole I Orazio
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, California, 92037, USA
| | - Brittany Goben
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California, 92037, USA
| | - Jill Meisenhelder
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California, 92037, USA
| | - Zhongsheng You
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, 63110, USA
| | - Matthew D Weitzman
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, California, 92037, USA.
| | - Tony Hunter
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California, 92037, USA.
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44
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Makharashvili N, Arora S, Yin Y, Fu Q, Wen X, Lee JH, Kao CH, Leung JWC, Miller KM, Paull TT. Sae2/CtIP prevents R-loop accumulation in eukaryotic cells. eLife 2018; 7:e42733. [PMID: 30523780 PMCID: PMC6296784 DOI: 10.7554/elife.42733] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 11/30/2018] [Indexed: 02/06/2023] Open
Abstract
The Sae2/CtIP protein is required for efficient processing of DNA double-strand breaks that initiate homologous recombination in eukaryotic cells. Sae2/CtIP is also important for survival of single-stranded Top1-induced lesions and CtIP is known to associate directly with transcription-associated complexes in mammalian cells. Here we investigate the role of Sae2/CtIP at single-strand lesions in budding yeast and in human cells and find that depletion of Sae2/CtIP promotes the accumulation of stalled RNA polymerase and RNA-DNA hybrids at sites of highly expressed genes. Overexpression of the RNA-DNA helicase Senataxin suppresses DNA damage sensitivity and R-loop accumulation in Sae2/CtIP-deficient cells, and a catalytic mutant of CtIP fails to complement this sensitivity, indicating a role for CtIP nuclease activity in the repair process. Based on this evidence, we propose that R-loop processing by 5' flap endonucleases is a necessary step in the stabilization and removal of nascent R-loop initiating structures in eukaryotic cells.
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Affiliation(s)
- Nodar Makharashvili
- Howard Hughes Medical Institute, The University of Texas at AustinAustinUnited states
- Department of Molecular BiosciencesThe University of Texas at AustinAustinUnited States
| | - Sucheta Arora
- Howard Hughes Medical Institute, The University of Texas at AustinAustinUnited states
- Department of Molecular BiosciencesThe University of Texas at AustinAustinUnited States
| | - Yizhi Yin
- Howard Hughes Medical Institute, The University of Texas at AustinAustinUnited states
- Department of Molecular BiosciencesThe University of Texas at AustinAustinUnited States
| | - Qiong Fu
- Gastrointestinal Malignancy Section, Thoracic and Gastrointestinal Oncology Branch, Center for Cancer ResearchNational Cancer Institute, National Institutes of HealthBethesdaUnited States
| | - Xuemei Wen
- Department of Molecular BiosciencesThe University of Texas at AustinAustinUnited States
| | - Ji-Hoon Lee
- Department of Molecular BiosciencesThe University of Texas at AustinAustinUnited States
| | - Chung-Hsuan Kao
- Department of Molecular BiosciencesThe University of Texas at AustinAustinUnited States
| | - Justin WC Leung
- Department of Radiation OncologyUniversity of Arkansas for Medical SciencesLittle RockUnited States
| | - Kyle M Miller
- Department of Molecular BiosciencesThe University of Texas at AustinAustinUnited States
| | - Tanya T Paull
- Howard Hughes Medical Institute, The University of Texas at AustinAustinUnited states
- Department of Molecular BiosciencesThe University of Texas at AustinAustinUnited States
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45
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Wang H, Qiu Z, Liu B, Wu Y, Ren J, Liu Y, Zhao Y, Wang Y, Hao S, Li Z, Peng B, Xu X. PLK1 targets CtIP to promote microhomology-mediated end joining. Nucleic Acids Res 2018; 46:10724-10739. [PMID: 30202980 PMCID: PMC6237753 DOI: 10.1093/nar/gky810] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 08/08/2018] [Accepted: 08/30/2018] [Indexed: 12/12/2022] Open
Abstract
Proper DNA double-strand break (DSB) repair is essential for maintaining genome integrity. Microhomology-mediated end joining (MMEJ) is an error-prone repair mechanism, which introduces mutations at break sites and contributes to chromosomal translocations and telomere fusions, thus driving carcinogenesis. Mitotic kinases PLK1, CDK1 and Aurora A are important for supporting MMEJ and are often overexpressed in various tumors. However, the functional interplay between these kinases and MMEJ has not been explored. Here, we found that MMEJ is preferentially employed to fix DSBs in cells arrested in mitosis following nocodazole treatment. We further showed that the DSB repair factor CtIP is jointly phosphorylated by CDK1/Aurora A and PLK1. CDK1/Aurora A-mediated CtIP phosphorylation at serine 327 triggers CtIP binding to the PLK1 polo-box domain, which in turn facilitates PLK1 to phosphorylate CtIP mainly at serine 723. A PLK1 phosphor-mimic CtIP mutant fails to initiate extended end resection and is thus unable to mediate homologous recombination and the G2/M checkpoint but can mediate MMEJ. These data imply that PLK1 may target CtIP to promote error-prone MMEJ and inactivate the G2/M checkpoint. These findings have helped elucidate the oncogenic roles of these factors.
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Affiliation(s)
- Hailong Wang
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Zhiyu Qiu
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Bo Liu
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Yan Wu
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Jianping Ren
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Yaqing Liu
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Yuqin Zhao
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Ya Wang
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Shuailin Hao
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Zheng Li
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Bin Peng
- Guangdong Key Laboratory for Genome Stability & Disease Prevention, Shenzhen University School of Medicine, Shenzhen, Guangdong 518060, China
| | - Xingzhi Xu
- Guangdong Key Laboratory for Genome Stability & Disease Prevention, Shenzhen University School of Medicine, Shenzhen, Guangdong 518060, China
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46
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BRCA1 ensures genome integrity by eliminating estrogen-induced pathological topoisomerase II-DNA complexes. Proc Natl Acad Sci U S A 2018; 115:E10642-E10651. [PMID: 30352856 DOI: 10.1073/pnas.1803177115] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Women having BRCA1 germ-line mutations develop cancer in breast and ovary, estrogen-regulated tissues, with high penetrance. Binding of estrogens to the estrogen receptor (ER) transiently induces DNA double-strand breaks (DSBs) by topoisomerase II (TOP2) and controls gene transcription. TOP2 resolves catenated DNA by transiently generating DSBs, TOP2-cleavage complexes (TOP2ccs), where TOP2 covalently binds to 5' ends of DSBs. TOP2 frequently fails to complete its catalysis, leading to formation of pathological TOP2ccs. We have previously shown that the endonucleolytic activity of MRE11 plays a key role in removing 5' TOP2 adducts in G1 phase. We show here that BRCA1 promotes MRE11-mediated removal of TOP2 adducts in G1 phase. We disrupted the BRCA1 gene in 53BP1-deficient ER-positive breast cancer and B cells. The loss of BRCA1 caused marked increases of pathological TOP2ccs in G1 phase following exposure to etoposide, which generates pathological TOP2ccs. We conclude that BRCA1 promotes the removal of TOP2 adducts from DSB ends for subsequent nonhomologous end joining. BRCA1-deficient cells showed a decrease in etoposide-induced MRE11 foci in G1 phase, suggesting that BRCA1 repairs pathological TOP2ccs by promoting the recruitment of MRE11 to TOP2cc sites. BRCA1 depletion also leads to the increase of unrepaired DSBs upon estrogen treatment both in vitro in G1-arrested breast cancer cells and in vivo in epithelial cells of mouse mammary glands. BRCA1 thus plays a critical role in removing pathological TOP2ccs induced by estrogens as well as etoposide. We propose that BRCA1 suppresses tumorigenesis by removing estrogen-induced pathological TOP2ccs throughout the cell cycle.
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47
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Whelan DR, Lee WTC, Yin Y, Ofri DM, Bermudez-Hernandez K, Keegan S, Fenyo D, Rothenberg E. Spatiotemporal dynamics of homologous recombination repair at single collapsed replication forks. Nat Commun 2018; 9:3882. [PMID: 30250272 PMCID: PMC6155164 DOI: 10.1038/s41467-018-06435-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 09/06/2018] [Indexed: 01/07/2023] Open
Abstract
Homologous recombination (HR) is a crucial pathway for the repair of DNA double-strand breaks. BRCA1/2 breast cancer proteins are key players in HR via their mediation of RAD51 nucleofilament formation and function; however, their individual roles and crosstalk in vivo are unknown. Here we use super-resolution (SR) imaging to map the spatiotemporal kinetics of HR proteins, revealing the interdependent relationships that govern the dynamic interplay and progression of repair events. We show that initial single-stranded DNA/RAD51 nucleofilament formation is mediated by RAD52 or, in the absence of RAD52, by BRCA2. In contrast, only BRCA2 can orchestrate later RAD51 recombinase activity during homology search and resolution. Furthermore, we establish that upstream BRCA1 activity is critical for BRCA2 function. Our analyses reveal the underlying epistatic landscape of RAD51 functional dependence on RAD52, BRCA1, and BRCA2 during HR and explain the phenotypic similarity of diseases associated with mutations in these proteins.
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Affiliation(s)
- Donna R Whelan
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA.,Department of Pharmacy and Applied Science, La Trobe Institute for Molecular Science, La Trobe University, Bendigo, VIC, Australia
| | - Wei Ting C Lee
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA
| | - Yandong Yin
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA
| | - Dylan M Ofri
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA
| | - Keria Bermudez-Hernandez
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA
| | - Sarah Keegan
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA
| | - David Fenyo
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA.
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48
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Abstract
Canonical DNA non-homologous end-joining (c-NHEJ) and homologous recombination (HR), the two major DNA double-strand break (DSB) repair pathways, have long been depicted as competitors, fighting a race to rejoin DSBs. In human cells, Ku, an upstream component of NHEJ, is highly abundant and has exquisite end-binding capacity. Emerging evidence has suggested that Ku is the first protein binding most, if not all, DSBs, and creates a block to resection. Although most c-NHEJ proceeds without resection, recent studies have provided strong evidence for a process of resection-dependent c-NHEJ, that repairs a subset of DSBs. HR also repairs a subset of two-ended DSBs in G2 phase and processes one-ended DSBs that arise following replication fork stalling or collapse to promote replication restart. HR also necessitates end-resection. This raises the question of how end-resection takes place despite Ku's avid end-binding capacity. Insight into this enigma has been gained from the analysis of DSBs generated by Spo11 or TOP2, which create protein-bridged DSBs. The progression of repair by HR or NHEJ requires removal of the end-blocking lesions. The MRE11-RAD50-NBS1 (MRN) complex, CtIP and EXO1 play critical roles in this process. Here, we review our current understanding of how resection arises at lesions blocked by covalently bound Spo11 or TOP2 or following Ku binding, which effectively creates a distinct resection-blocking lesion due to its avid end-binding activity and abundance. Our review reveals that Ku plays an active role in determining pathway choice and exposes similarities yet distinctions in the progression of resection that is suited to the optimal repair pathway choice.
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Affiliation(s)
- Atsushi Shibata
- Education and Research Support Center, Graduate School of Medicine, Gunma University, Maebashi, Japan
| | - Penny Jeggo
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN19 RQ, UK
| | - Markus Löbrich
- Radiation Biology and DNA Repair, Darmstadt University of Technology, 64287 Darmstadt, Germany.
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49
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Paudyal SC, Li S, Yan H, Hunter T, You Z. Dna2 initiates resection at clean DNA double-strand breaks. Nucleic Acids Res 2017; 45:11766-11781. [PMID: 28981724 PMCID: PMC5714177 DOI: 10.1093/nar/gkx830] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 08/30/2017] [Accepted: 09/06/2017] [Indexed: 02/07/2023] Open
Abstract
Nucleolytic resection of DNA double-strand breaks (DSBs) is essential for both checkpoint activation and homology-mediated repair; however, the precise mechanism of resection, especially the initiation step, remains incompletely understood. Resection of blocked ends with protein or chemical adducts is believed to be initiated by the MRN complex in conjunction with CtIP through internal cleavage of the 5' strand DNA. However, it is not clear whether resection of clean DSBs with free ends is also initiated by the same mechanism. Using the Xenopus nuclear extract system, here we show that the Dna2 nuclease directly initiates the resection of clean DSBs by cleaving the 5' strand DNA ∼10-20 nucleotides away from the ends. In the absence of Dna2, MRN together with CtIP mediate an alternative resection initiation pathway where the nuclease activity of MRN apparently directly cleaves the 5' strand DNA at more distal sites. MRN also facilitates resection initiation by promoting the recruitment of Dna2 and CtIP to the DNA substrate. The ssDNA-binding protein RPA promotes both Dna2- and CtIP-MRN-dependent resection initiation, but a RPA mutant can distinguish between these pathways. Our results strongly suggest that resection of blocked and clean DSBs is initiated via distinct mechanisms.
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Affiliation(s)
- Sharad C. Paudyal
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Shan Li
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Hong Yan
- Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA
| | - Tony Hunter
- Salk Institute, 10010 N Torrey Pines Road, La Jolla, CA 92037, USA
| | - Zhongsheng You
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
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50
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DNA end resection requires constitutive sumoylation of CtIP by CBX4. Nat Commun 2017; 8:113. [PMID: 28740167 PMCID: PMC5524638 DOI: 10.1038/s41467-017-00183-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 06/07/2017] [Indexed: 11/20/2022] Open
Abstract
DNA breaks are complex DNA lesions that can be repaired by two alternative mechanisms: non-homologous end-joining and homologous recombination. The decision between them depends on the activation of the DNA resection machinery, which blocks non-homologous end-joining and stimulates recombination. On the other hand, post-translational modifications play a critical role in DNA repair. We have found that the SUMO E3 ligase CBX4 controls resection through the key factor CtIP. Indeed, CBX4 depletion impairs CtIP constitutive sumoylation and DNA end processing. Importantly, mutating lysine 896 in CtIP recapitulates the CBX4-depletion phenotype, blocks homologous recombination and increases genomic instability. Artificial fusion of CtIP and SUMO suppresses the effects of both the non-sumoylatable CtIP mutant and CBX4 depletion. Mechanistically, CtIP sumoylation is essential for its recruitment to damaged DNA. In summary, sumoylation of CtIP at lysine 896 defines a subpopulation of the protein that is involved in DNA resection and recombination. The choice between non-homologous end-joining and homologous recombination to repair a DNA double-strand break depends on activation of the end resection machinery. Here the authors show that SUMO E3 ligase CBX4 sumoylates subpopulation of CtIP to regulate recruitment to breaks and resection.
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