101
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Polleys EJ, Freudenreich CH. Homologous recombination within repetitive DNA. Curr Opin Genet Dev 2021; 71:143-153. [PMID: 34464817 DOI: 10.1016/j.gde.2021.08.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 08/06/2021] [Accepted: 08/12/2021] [Indexed: 12/16/2022]
Abstract
Many microsatellite DNA sequences are able to form non-B form DNA secondary structures, such as hairpin loops, cruciforms, triplex DNA or G-quadruplexes. These DNA structures can form a significant impediment to DNA replication and repair, leading to DNA nicks, gaps, and breaks, which can be repaired by homologous recombination (HR). Recent work understanding HR at structure-forming repeats has focused on genetic requirements for replication fork restart, break induced replication (BIR) at broken forks, recombination during and after relocalization of breaks or stalled forks to the nuclear periphery, and how repair pathway choice and kinetics are navigated in the presence of a repeat tract. In this review, we summarize recent developments that illuminate the role of recombination in repairing DNA damage or causing tract length changes within repetitive DNA and its role in maintaining genome stability.
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Affiliation(s)
- Erica J Polleys
- Department of Biology, Tufts University, Medford MA 02155, United States
| | - Catherine H Freudenreich
- Department of Biology, Tufts University, Medford MA 02155, United States; Program in Genetics, Tufts University, Boston MA 02111, United States.
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102
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Cellular functions of the protein kinase ATM and their relevance to human disease. Nat Rev Mol Cell Biol 2021; 22:796-814. [PMID: 34429537 DOI: 10.1038/s41580-021-00394-2] [Citation(s) in RCA: 110] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2021] [Indexed: 02/07/2023]
Abstract
The protein kinase ataxia telangiectasia mutated (ATM) is a master regulator of double-strand DNA break (DSB) signalling and stress responses. For three decades, ATM has been investigated extensively to elucidate its roles in the DNA damage response (DDR) and in the pathogenesis of ataxia telangiectasia (A-T), a human neurodegenerative disease caused by loss of ATM. Although hundreds of proteins have been identified as ATM phosphorylation targets and many important roles for this kinase have been identified, it is still unclear how ATM deficiency leads to the early-onset cerebellar degeneration that is common in all individuals with A-T. Recent studies suggest the existence of links between ATM deficiency and other cerebellum-specific neurological disorders, as well as the existence of broader similarities with more common neurodegenerative disorders. In this Review, we discuss recent structural insights into ATM regulation, and possible aetiologies of A-T phenotypes, including reactive oxygen species, mitochondrial dysfunction, alterations in transcription, R-loop metabolism and alternative splicing, defects in cellular proteostasis and metabolism, and potential pathogenic roles for hyper-poly(ADP-ribosyl)ation.
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103
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Guha S, Bhaumik SR. Transcription-coupled DNA double-strand break repair. DNA Repair (Amst) 2021; 109:103211. [PMID: 34883263 DOI: 10.1016/j.dnarep.2021.103211] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 08/11/2021] [Accepted: 08/11/2021] [Indexed: 12/20/2022]
Abstract
The genomic DNA is constantly under attack by cellular and/or environmental factors. Fortunately, the cell is armed to safeguard its genome by various mechanisms such as nucleotide excision, base excision, mismatch and DNA double-strand break repairs. While these processes maintain the integrity of the genome throughout, DNA repair occurs preferentially faster at the transcriptionally active genes. Such transcription-coupled repair phenomenon plays important roles to maintain active genome integrity, failure of which would interfere with transcription, leading to an altered gene expression (and hence cellular pathologies/diseases). Among the various DNA damages, DNA double-strand breaks are quite toxic to the cells. If DNA double-strand break occurs at the active gene, it would interfere with transcription/gene expression, thus threatening cellular viability. Such DNA double-strand breaks are found to be repaired faster at the active gene in comparison to its inactive state or the inactive gene, thus supporting the existence of a new phenomenon of transcription-coupled DNA double-strand break repair. Here, we describe the advances of this repair process.
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Affiliation(s)
- Shalini Guha
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL, 62901, USA
| | - Sukesh R Bhaumik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL, 62901, USA.
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104
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Nickoloff JA, Sharma N, Allen CP, Taylor L, Allen SJ, Jaiswal AS, Hromas R. Roles of homologous recombination in response to ionizing radiation-induced DNA damage. Int J Radiat Biol 2021; 99:903-914. [PMID: 34283012 PMCID: PMC9629169 DOI: 10.1080/09553002.2021.1956001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/04/2021] [Accepted: 07/05/2021] [Indexed: 02/06/2023]
Abstract
PURPOSE Ionizing radiation induces a vast array of DNA lesions including base damage, and single- and double-strand breaks (SSB, DSB). DSBs are among the most cytotoxic lesions, and mis-repair causes small- and large-scale genome alterations that can contribute to carcinogenesis. Indeed, ionizing radiation is a 'complete' carcinogen. DSBs arise immediately after irradiation, termed 'frank DSBs,' as well as several hours later in a replication-dependent manner, termed 'secondary' or 'replication-dependent DSBs. DSBs resulting from replication fork collapse are single-ended and thus pose a distinct problem from two-ended, frank DSBs. DSBs are repaired by error-prone nonhomologous end-joining (NHEJ), or generally error-free homologous recombination (HR), each with sub-pathways. Clarifying how these pathways operate in normal and tumor cells is critical to increasing tumor control and minimizing side effects during radiotherapy. CONCLUSIONS The choice between NHEJ and HR is regulated during the cell cycle and by other factors. DSB repair pathways are major contributors to cell survival after ionizing radiation, including tumor-resistance to radiotherapy. Several nucleases are important for HR-mediated repair of replication-dependent DSBs and thus replication fork restart. These include three structure-specific nucleases, the 3' MUS81 nuclease, and two 5' nucleases, EEPD1 and Metnase, as well as three end-resection nucleases, MRE11, EXO1, and DNA2. The three structure-specific nucleases evolved at very different times, suggesting incremental acceleration of replication fork restart to limit toxic HR intermediates and genome instability as genomes increased in size during evolution, including the gain of large numbers of HR-prone repetitive elements. Ionizing radiation also induces delayed effects, observed days to weeks after exposure, including delayed cell death and delayed HR. In this review we highlight the roles of HR in cellular responses to ionizing radiation, and discuss the importance of HR as an exploitable target for cancer radiotherapy.
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Affiliation(s)
- Jac A. Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
| | - Neelam Sharma
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
| | - Christopher P. Allen
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
- Department of Microbiology, Immunology and Pathology, Flow Cytometry and Cell Sorting Facility, Colorado State University, Fort Collins, CO, USA
| | - Lynn Taylor
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
| | - Sage J. Allen
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
| | - Aruna S. Jaiswal
- Division of Hematology and Medical Oncology, Department of Medicine and the Mays Cancer Center, University of Texas Health Science Center, San Antonio, TX, USA
| | - Robert Hromas
- Division of Hematology and Medical Oncology, Department of Medicine and the Mays Cancer Center, University of Texas Health Science Center, San Antonio, TX, USA
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105
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Liang S, Chaplin AK, Stavridi AK, Appleby R, Hnizda A, Blundell TL. Stages, scaffolds and strings in the spatial organisation of non-homologous end joining: Insights from X-ray diffraction and Cryo-EM. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 163:60-73. [PMID: 33285184 PMCID: PMC8224183 DOI: 10.1016/j.pbiomolbio.2020.11.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 11/26/2020] [Indexed: 01/10/2023]
Abstract
Non-homologous end joining (NHEJ) is the preferred pathway for the repair of DNA double-strand breaks in humans. Here we describe three structural aspects of the repair pathway: stages, scaffolds and strings. We discuss the orchestration of DNA repair to guarantee robust and efficient NHEJ. We focus on structural studies over the past two decades, not only using X-ray diffraction, but also increasingly exploiting cryo-EM to investigate the macromolecular assemblies.
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Affiliation(s)
- Shikang Liang
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, Cambridgeshire, UK
| | - Amanda K Chaplin
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, Cambridgeshire, UK
| | - Antonia Kefala Stavridi
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, Cambridgeshire, UK
| | - Robert Appleby
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, Cambridgeshire, UK
| | - Ales Hnizda
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, Cambridgeshire, UK
| | - Tom L Blundell
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, Cambridgeshire, UK.
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106
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Ye Z, Xu S, Shi Y, Bacolla A, Syed A, Moiani D, Tsai CL, Shen Q, Peng G, Leonard PG, Jones DE, Wang B, Tainer JA, Ahmed Z. GRB2 enforces homology-directed repair initiation by MRE11. SCIENCE ADVANCES 2021; 7:7/32/eabe9254. [PMID: 34348893 PMCID: PMC8336959 DOI: 10.1126/sciadv.abe9254] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 06/17/2021] [Indexed: 05/10/2023]
Abstract
DNA double-strand break (DSB) repair is initiated by MRE11 nuclease for both homology-directed repair (HDR) and alternative end joining (Alt-EJ). Here, we found that GRB2, crucial to timely proliferative RAS/MAPK pathway activation, unexpectedly forms a biophysically validated GRB2-MRE11 (GM) complex for efficient HDR initiation. GRB2-SH2 domain targets the GM complex to phosphorylated H2AX at DSBs. GRB2 K109 ubiquitination by E3 ubiquitin ligase RBBP6 releases MRE11 promoting HDR. RBBP6 depletion results in prolonged GM complex and HDR defects. GRB2 knockout increased MRE11-XRCC1 complex and Alt-EJ. Reconstitution with separation-of-function GRB2 mutant caused HDR deficiency and synthetic lethality with PARP inhibitor. Cell and cancer genome analyses suggest biomarkers of low GRB2 for noncanonical HDR deficiency and high MRE11 and GRB2 expression for worse survival in HDR-proficient patients. These findings establish GRB2's role in binding, targeting, and releasing MRE11 to promote efficient HDR over Alt-EJ DSB repair, with implications for genome stability and cancer biology.
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Affiliation(s)
- Zu Ye
- Departments of Molecular and Cellular Oncology and Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Shengfeng Xu
- Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yin Shi
- Department of Biochemistry, Zhejiang University School of Medicine, Hangzhou 310058, China
- Division of Pediatrics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Albino Bacolla
- Departments of Molecular and Cellular Oncology and Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Aleem Syed
- Departments of Molecular and Cellular Oncology and Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Davide Moiani
- Departments of Molecular and Cellular Oncology and Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Chi-Lin Tsai
- Departments of Molecular and Cellular Oncology and Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Qiang Shen
- Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Guang Peng
- Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Paul G Leonard
- Institute for Applied Cancer Science, The University of Texas MD Anderson Cancer Center, 1881 East Road, Houston, TX 77054, USA
| | - Darin E Jones
- Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA
| | - Bin Wang
- Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - John A Tainer
- Departments of Molecular and Cellular Oncology and Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
| | - Zamal Ahmed
- Departments of Molecular and Cellular Oncology and Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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107
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DNA end resection during homologous recombination. Curr Opin Genet Dev 2021; 71:99-105. [PMID: 34329854 DOI: 10.1016/j.gde.2021.07.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/03/2021] [Accepted: 07/05/2021] [Indexed: 12/15/2022]
Abstract
Exposure to environmental mutagens but also cell-endogenous processes can create DNA double-strand breaks (DSBs) in a cell's genome. DSBs need to be repaired accurately and timely to ensure genomic integrity and cell survival. One major DSB repair mechanism, called homologous recombination, relies on the nucleolytic degradation of the 5'-terminated strands in a process termed end resection. Here, we review new insights into end resection with a focus on the mechanistic interplay of the nucleases, helicases, and accessory factors involved.
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108
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Transcription/Replication Conflicts in Tumorigenesis and Their Potential Role as Novel Therapeutic Targets in Multiple Myeloma. Cancers (Basel) 2021; 13:cancers13153755. [PMID: 34359660 PMCID: PMC8345052 DOI: 10.3390/cancers13153755] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/13/2021] [Accepted: 07/22/2021] [Indexed: 12/24/2022] Open
Abstract
Simple Summary Multiple myeloma is a hematologic cancer characterized by the accumulation of malignant plasma cells in the bone marrow. It remains a mostly incurable disease due to the inability to overcome refractory disease and drug-resistant relapse. Oncogenic transformation of PC in multiple myeloma is thought to occur within the secondary lymphoid organs. However, the precise molecular events leading to myelomagenesis remain obscure. Here, we identified genes involved in the prevention and the resolution of conflicts between the replication and transcription significantly overexpressed during the plasma cell differentiation process and in multiple myeloma cells. We discussed the potential role of these factors in myelomagenesis and myeloma biology. The specific targeting of these factors might constitute a new therapeutic strategy in multiple myeloma. Abstract Plasma cells (PCs) have an essential role in humoral immune response by secretion of antibodies, and represent the final stage of B lymphocytes differentiation. During this differentiation, the pre-plasmablastic stage is characterized by highly proliferative cells that start to secrete immunoglobulins (Igs). Thus, replication and transcription must be tightly regulated in these cells to avoid transcription/replication conflicts (TRCs), which could increase replication stress and lead to genomic instability. In this review, we analyzed expression of genes involved in TRCs resolution during B to PC differentiation and identified 41 genes significantly overexpressed in the pre-plasmablastic stage. This illustrates the importance of mechanisms required for adequate processing of TRCs during PCs differentiation. Furthermore, we identified that several of these factors were also found overexpressed in purified PCs from patients with multiple myeloma (MM) compared to normal PCs. Malignant PCs produce high levels of Igs concomitantly with cell cycle deregulation. Therefore, increasing the TRCs occurring in MM cells could represent a potent therapeutic strategy for MM patients. Here, we describe the potential roles of TRCs resolution factors in myelomagenesis and discuss the therapeutic interest of targeting the TRCs resolution machinery in MM.
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109
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Paull TT. Reconsidering pathway choice: a sequential model of mammalian DNA double-strand break pathway decisions. Curr Opin Genet Dev 2021; 71:55-62. [PMID: 34293662 DOI: 10.1016/j.gde.2021.06.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 06/14/2021] [Accepted: 06/29/2021] [Indexed: 12/27/2022]
Abstract
DNA double-strand breaks can be repaired through ligation-based pathways (non-homologous end-joining) or replication-based pathways (homologous recombination) in eukaryotic cells. The decisions that govern these outcomes are widely viewed as a competition between factors that recognize DNA ends and physically promote association of factors specific to each pathway, commonly known as 'pathway choice'. Here I review recent results in the literature and propose that this decision is better described as a sequential set of binding and end processing events, with non-homologous end joining as the first decision point. Physical association and co-localization of end resection factors with non-homologous end-joining factors suggests that ends are transferred between these complexes, thus the ultimate outcome is not the result of a competition but is more akin to a relay race that is determined by the efficiency of the initial end-joining event and the availability of activated DNA end-processing enzymes.
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Affiliation(s)
- Tanya T Paull
- The University of Texas at Austin, Department of Molecular Biosciences, Austin, TX, 78712, United States.
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110
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Bazzano D, Lomonaco S, Wilson TE. Mapping yeast mitotic 5' resection at base resolution reveals the sequence and positional dependence of nucleases in vivo. Nucleic Acids Res 2021; 49:12607-12621. [PMID: 34263309 PMCID: PMC8682756 DOI: 10.1093/nar/gkab597] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 06/22/2021] [Accepted: 06/28/2021] [Indexed: 02/06/2023] Open
Abstract
Resection of the 5′-terminated strand at DNA double-strand breaks (DSBs) is the critical regulated step in the transition to homologous recombination. Recent studies have described a multi-step model of DSB resection where endonucleolytic cleavage mediated by Mre11 and Sae2 leads to further degradation mediated by redundant pathways catalyzed by Exo1 and Sgs1/Dna2. These models have not been well tested at mitotic DSBs in vivo because most methods used to monitor resection cannot precisely map early cleavage events. Here we report resection monitoring with high-throughput sequencing using molecular identifiers, allowing exact counting of cleaved 5′ ends at base resolution. Mutant strains, including exo1Δ, mre11-H125N and exo1Δ sgs1Δ, revealed a major Mre11-dependent cleavage position 60–70 bp from the DSB end whose exact position depended on local sequence. They further revealed an Exo1-dependent pause point approximately 200 bp from the DSB. Suppressing resection extension in exo1Δ sgs1Δ yeast exposed a footprint of regions where cleavage was restricted within 119 bp of the DSB. These results provide detailed in vivo views of prevailing models of DSB resection and extend them to show the combined influence of sequence specificity and access restrictions on Mre11 and Exo1 nucleases.
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Affiliation(s)
- Dominic Bazzano
- Department of Pathology, Ann Arbor, MI 48109, USA
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Thomas E Wilson
- To whom correspondence should be addressed. Tel: +1 734 764 2212;
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111
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Mancini M, Magnani E, Macchi F, Bonapace IM. The multi-functionality of UHRF1: epigenome maintenance and preservation of genome integrity. Nucleic Acids Res 2021; 49:6053-6068. [PMID: 33939809 PMCID: PMC8216287 DOI: 10.1093/nar/gkab293] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 04/02/2021] [Accepted: 04/12/2021] [Indexed: 12/23/2022] Open
Abstract
During S phase, the cooperation between the macromolecular complexes regulating DNA synthesis, epigenetic information maintenance and DNA repair is advantageous for cells, as they can rapidly detect DNA damage and initiate the DNA damage response (DDR). UHRF1 is a fundamental epigenetic regulator; its ability to coordinate DNA methylation and histone code is unique across proteomes of different species. Recently, UHRF1’s role in DNA damage repair has been explored and recognized to be as important as its role in maintaining the epigenome. UHRF1 is a sensor for interstrand crosslinks and a determinant for the switch towards homologous recombination in the repair of double-strand breaks; its loss results in enhanced sensitivity to DNA damage. These functions are finely regulated by specific post-translational modifications and are mediated by the SRA domain, which binds to damaged DNA, and the RING domain. Here, we review recent studies on the role of UHRF1 in DDR focusing on how it recognizes DNA damage and cooperates with other proteins in its repair. We then discuss how UHRF1’s epigenetic abilities in reading and writing histone modifications, or its interactions with ncRNAs, could interlace with its role in DDR.
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Affiliation(s)
- Monica Mancini
- Department of Biotechnology and Life Sciences, University of Insubria, Busto Arsizio, VA 21052, Italy
| | - Elena Magnani
- Program in Biology, New York University Abu Dhabi, Abu Dhabi, PO Box 129188, United Arab Emirates
| | - Filippo Macchi
- Program in Biology, New York University Abu Dhabi, Abu Dhabi, PO Box 129188, United Arab Emirates
| | - Ian Marc Bonapace
- Department of Biotechnology and Life Sciences, University of Insubria, Busto Arsizio, VA 21052, Italy
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112
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Ackerson SM, Romney C, Schuck PL, Stewart JA. To Join or Not to Join: Decision Points Along the Pathway to Double-Strand Break Repair vs. Chromosome End Protection. Front Cell Dev Biol 2021; 9:708763. [PMID: 34322492 PMCID: PMC8311741 DOI: 10.3389/fcell.2021.708763] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 06/17/2021] [Indexed: 01/01/2023] Open
Abstract
The regulation of DNA double-strand breaks (DSBs) and telomeres are diametrically opposed in the cell. DSBs are considered one of the most deleterious forms of DNA damage and must be quickly recognized and repaired. Telomeres, on the other hand, are specialized, stable DNA ends that must be protected from recognition as DSBs to inhibit unwanted chromosome fusions. Decisions to join DNA ends, or not, are therefore critical to genome stability. Yet, the processing of telomeres and DSBs share many commonalities. Accordingly, key decision points are used to shift DNA ends toward DSB repair vs. end protection. Additionally, DSBs can be repaired by two major pathways, namely homologous recombination (HR) and non-homologous end joining (NHEJ). The choice of which repair pathway is employed is also dictated by a series of decision points that shift the break toward HR or NHEJ. In this review, we will focus on these decision points and the mechanisms that dictate end protection vs. DSB repair and DSB repair choice.
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Affiliation(s)
- Stephanie M Ackerson
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - Carlan Romney
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - P Logan Schuck
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - Jason A Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
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113
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Cheng X, Côté V, Côté J. NuA4 and SAGA acetyltransferase complexes cooperate for repair of DNA breaks by homologous recombination. PLoS Genet 2021; 17:e1009459. [PMID: 34228704 PMCID: PMC8284799 DOI: 10.1371/journal.pgen.1009459] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 07/16/2021] [Accepted: 06/21/2021] [Indexed: 12/30/2022] Open
Abstract
Chromatin modifying complexes play important yet not fully defined roles in DNA repair processes. The essential NuA4 histone acetyltransferase (HAT) complex is recruited to double-strand break (DSB) sites and spreads along with DNA end resection. As predicted, NuA4 acetylates surrounding nucleosomes upon DSB induction and defects in its activity correlate with altered DNA end resection and Rad51 recombinase recruitment. Importantly, we show that NuA4 is also recruited to the donor sequence during recombination along with increased H4 acetylation, indicating a direct role during strand invasion/D-loop formation after resection. We found that NuA4 cooperates locally with another HAT, the SAGA complex, during DSB repair as their combined action is essential for DNA end resection to occur. This cooperation of NuA4 and SAGA is required for recruitment of ATP-dependent chromatin remodelers, targeted acetylation of repair factors and homologous recombination. Our work reveals a multifaceted and conserved cooperation mechanism between acetyltransferase complexes to allow repair of DNA breaks by homologous recombination. DNA double-strand breaks (DSBs) are among the most dangerous types of DNA lesions as they can produce genomic instability that leads to cancer and genetic diseases. It is therefore crucial to understand the precise molecular mechanisms used by cells to detect and repair this type of damages. Homologous recombination using sister chromatid as template is the most accurate pathway to repair these breaks but has to occur within the context of the DNA compacted structure in chromosomes. Here, we show that two enzymes, NuA4 and SAGA, that acetylate the structural components of chromosomes in the vicinity of the DNA breaks are together essential for recombination-mediated repair to occur. We found that they are recruited at an early step after damage detection and their action allows subsequent remodeling of local structural organisation by other enzymes, providing DNA access to the recombination machinery. These results highlight the cooperation of enzymes for a same goal, providing robustness in the repair process as only the loss of both leads to major defects.
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Affiliation(s)
- Xue Cheng
- St-Patrick Research Group in Basic Oncology, Laval University Cancer Research Center, Oncology Division of CHU de Québec-Université Laval Research Center, Quebec City, Canada
| | - Valérie Côté
- St-Patrick Research Group in Basic Oncology, Laval University Cancer Research Center, Oncology Division of CHU de Québec-Université Laval Research Center, Quebec City, Canada
| | - Jacques Côté
- St-Patrick Research Group in Basic Oncology, Laval University Cancer Research Center, Oncology Division of CHU de Québec-Université Laval Research Center, Quebec City, Canada
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114
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Xue C, Greene EC. DNA Repair Pathway Choices in CRISPR-Cas9-Mediated Genome Editing. Trends Genet 2021; 37:639-656. [PMID: 33896583 PMCID: PMC8187289 DOI: 10.1016/j.tig.2021.02.008] [Citation(s) in RCA: 128] [Impact Index Per Article: 42.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/25/2021] [Accepted: 02/26/2021] [Indexed: 12/14/2022]
Abstract
Many clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9)-based genome editing technologies take advantage of Cas nucleases to induce DNA double-strand breaks (DSBs) at desired locations within a genome. Further processing of the DSBs by the cellular DSB repair machinery is then necessary to introduce desired mutations, sequence insertions, or gene deletions. Thus, the accuracy and efficiency of genome editing are influenced by the cellular DSB repair pathways. DSBs are themselves highly genotoxic lesions and as such cells have evolved multiple mechanisms for their repair. These repair pathways include homologous recombination (HR), classical nonhomologous end joining (cNHEJ), microhomology-mediated end joining (MMEJ) and single-strand annealing (SSA). In this review, we briefly highlight CRISPR-Cas9 and then describe the mechanisms of DSB repair. Finally, we summarize recent findings of factors that can influence the choice of DNA repair pathway in response to Cas9-induced DSBs.
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Affiliation(s)
- Chaoyou Xue
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Eric C Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
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115
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Wang Y, Zheng K, Huang Y, Xiong H, Su J, Chen R, Zou Y. PARP inhibitors in gastric cancer: beacon of hope. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2021; 40:211. [PMID: 34167572 PMCID: PMC8228511 DOI: 10.1186/s13046-021-02005-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 06/03/2021] [Indexed: 12/14/2022]
Abstract
Defects in the DNA damage response (DDR) can lead to genome instability, producing mutations or aberrations that promote the development and progression of cancer. But it also confers such cells vulnerable to cell death when they inhibit DNA damage repair. Poly (ADP-ribose) polymerase (PARP) plays a central role in many cellular processes, including DNA repair, replication, and transcription. PARP induces the occurrence of poly (ADP-ribosylation) (PARylation) when DNA single strand breaks (SSB) occur. PARP and various proteins can interact directly or indirectly through PARylation to regulate DNA repair. Inhibitors that directly target PARP have been found to block the SSB repair pathway, triggering homologous recombination deficiency (HRD) cancers to form synthetic lethal concepts that represent an anticancer strategy. It has therefore been investigated in many cancer types for more effective anti-cancer strategies, including gastric cancer (GC). This review describes the antitumor mechanisms of PARP inhibitors (PARPis), and the preclinical and clinical progress of PARPis as monotherapy and combination therapy in GC.
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Affiliation(s)
- Yali Wang
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Jiefang Road, Wuhan, 430030, Hubei, China
| | - Kun Zheng
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Jiefang Road, Wuhan, 430030, Hubei, China
| | - Yongbiao Huang
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Jiefang Road, Wuhan, 430030, Hubei, China
| | - Hua Xiong
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Jiefang Road, Wuhan, 430030, Hubei, China
| | - Jinfang Su
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Jiefang Road, Wuhan, 430030, Hubei, China
| | - Rui Chen
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Jiefang Road, Wuhan, 430030, Hubei, China
| | - Yanmei Zou
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Jiefang Road, Wuhan, 430030, Hubei, China.
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116
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Shkundina IS, Gall AA, Dick A, Cocklin S, Mazin AV. New RAD51 Inhibitors to Target Homologous Recombination in Human Cells. Genes (Basel) 2021; 12:genes12060920. [PMID: 34208492 PMCID: PMC8235719 DOI: 10.3390/genes12060920] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/10/2021] [Accepted: 06/11/2021] [Indexed: 12/31/2022] Open
Abstract
Targeting DNA repair proteins with small-molecule inhibitors became a proven anti-cancer strategy. Previously, we identified an inhibitor of a major protein of homologous recombination (HR) RAD51, named B02. B02 inhibited HR in human cells and sensitized them to chemotherapeutic drugs in vitro and in vivo. Here, using a medicinal chemistry approach, we aimed to improve the potency of B02. We identified the B02 analog, B02-isomer, which inhibits HR in human cells with significantly higher efficiency. We also show that B02-iso sensitizes triple-negative breast cancer MDA-MB-231 cells to the PARP inhibitor (PARPi) olaparib.
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Affiliation(s)
- Irina S. Shkundina
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA; (I.S.S.); (A.D.); (S.C.)
| | | | - Alexej Dick
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA; (I.S.S.); (A.D.); (S.C.)
| | - Simon Cocklin
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA; (I.S.S.); (A.D.); (S.C.)
| | - Alexander V. Mazin
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA; (I.S.S.); (A.D.); (S.C.)
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
- Correspondence:
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117
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Senataxin Ortholog Sen1 Limits DNA:RNA Hybrid Accumulation at DNA Double-Strand Breaks to Control End Resection and Repair Fidelity. Cell Rep 2021; 31:107603. [PMID: 32375052 DOI: 10.1016/j.celrep.2020.107603] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 03/07/2020] [Accepted: 04/10/2020] [Indexed: 11/20/2022] Open
Abstract
An important but still enigmatic function of DNA:RNA hybrids is their role in DNA double-strand break (DSB) repair. Here, we show that Sen1, the budding yeast ortholog of the human helicase Senataxin, is recruited at an HO endonuclease-induced DSB and limits the local accumulation of DNA:RNA hybrids. In the absence of Sen1, hybrid accumulation proximal to the DSB promotes increased binding of the Ku70-80 (KU) complex at the break site, mutagenic non-homologous end joining (NHEJ), micro-homology-mediated end joining (MMEJ), and chromosome translocations. We also show that homology-directed recombination (HDR) by gene conversion is mostly proficient in sen1 mutants after single DSB. However, in the absence of Sen1, DNA:RNA hybrids, Mre11, and Dna2 initiate resection through a non-canonical mechanism. We propose that this resection mechanism through local DNA:RNA hybrids acts as a backup to prime HDR when canonical pathways are altered, but at the expense of genome integrity.
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118
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Averbek S, Jakob B, Durante M, Averbeck NB. O-GlcNAcylation Affects the Pathway Choice of DNA Double-Strand Break Repair. Int J Mol Sci 2021; 22:ijms22115715. [PMID: 34071949 PMCID: PMC8198441 DOI: 10.3390/ijms22115715] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 05/20/2021] [Accepted: 05/21/2021] [Indexed: 12/13/2022] Open
Abstract
Exposing cells to DNA damaging agents, such as ionizing radiation (IR) or cytotoxic chemicals, can cause DNA double-strand breaks (DSBs), which are crucial to repair to maintain genetic integrity. O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) is a post-translational modification (PTM), which has been reported to be involved in the DNA damage response (DDR) and chromatin remodeling. Here, we investigated the impact of O-GlcNAcylation on the DDR, DSB repair and chromatin status in more detail. We also applied charged particle irradiation to analyze differences of O-GlcNAcylation and its impact on DSB repair in respect of spatial dose deposition and radiation quality. Various techniques were used, such as the γH2AX foci assay, live cell microscopy and Fluorescence Lifetime Microscopy (FLIM) to detect DSB rejoining, protein accumulation and chromatin states after treating the cells with O-GlcNAc transferase (OGT) or O-GlcNAcase (OGA) inhibitors. We confirmed that O-GlcNAcylation of MDC1 is increased upon irradiation and identified additional repair factors related to Homologous Recombination (HR), CtIP and BRCA1, which were increasingly O-GlcNAcyated upon irradiation. This is consistent with our findings that the function of HR is affected by OGT inhibition. Besides, we found that OGT and OGA activity modulate chromatin compaction states, providing a potential additional level of DNA-repair regulation.
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Affiliation(s)
- Sera Averbek
- Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany; (S.A.); (B.J.); (M.D.)
- Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Burkhard Jakob
- Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany; (S.A.); (B.J.); (M.D.)
| | - Marco Durante
- Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany; (S.A.); (B.J.); (M.D.)
- Department of Physics, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Nicole B. Averbeck
- Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany; (S.A.); (B.J.); (M.D.)
- Correspondence:
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119
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San Martin Alonso M, Noordermeer S. Untangling the crosstalk between BRCA1 and R-loops during DNA repair. Nucleic Acids Res 2021; 49:4848-4863. [PMID: 33755171 PMCID: PMC8136775 DOI: 10.1093/nar/gkab178] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 02/25/2021] [Accepted: 03/04/2021] [Indexed: 01/13/2023] Open
Abstract
R-loops are RNA:DNA hybrids assembled during biological processes but are also linked to genetic instability when formed out of their natural context. Emerging evidence suggests that the repair of DNA double-strand breaks requires the formation of a transient R-loop, which eventually must be removed to guarantee a correct repair process. The multifaceted BRCA1 protein has been shown to be recruited at this specific break-induced R-loop, and it facilitates mechanisms in order to regulate R-loop removal. In this review, we discuss the different potential roles of BRCA1 in R-loop homeostasis during DNA repair and how these processes ensure faithful DSB repair.
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Affiliation(s)
- Marta San Martin Alonso
- Leiden University Medical Center, Department of Human Genetics, Leiden, The Netherlands
- Oncode Institute, Utrecht, The Netherlands
| | - Sylvie M Noordermeer
- Leiden University Medical Center, Department of Human Genetics, Leiden, The Netherlands
- Oncode Institute, Utrecht, The Netherlands
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120
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Hernandez Sanchez-Rebato M, Bouatta AM, Gallego ME, White CI, Da Ines O. RAD54 is essential for RAD51-mediated repair of meiotic DSB in Arabidopsis. PLoS Genet 2021; 17:e1008919. [PMID: 34003859 PMCID: PMC8162660 DOI: 10.1371/journal.pgen.1008919] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 05/28/2021] [Accepted: 05/03/2021] [Indexed: 12/17/2022] Open
Abstract
An essential component of the homologous recombination machinery in eukaryotes, the RAD54 protein is a member of the SWI2/SNF2 family of helicases with dsDNA-dependent ATPase, DNA translocase, DNA supercoiling and chromatin remodelling activities. It is a motor protein that translocates along dsDNA and performs multiple functions in homologous recombination. In particular, RAD54 is an essential cofactor for regulating RAD51 activity. It stabilizes the RAD51 nucleofilament, remodels nucleosomes, and stimulates the homology search and strand invasion activities of RAD51. Accordingly, deletion of RAD54 has dramatic consequences on DNA damage repair in mitotic cells. In contrast, its role in meiotic recombination is less clear. RAD54 is essential for meiotic recombination in Drosophila and C. elegans, but plays minor roles in yeast and mammals. We present here characterization of the roles of RAD54 in meiotic recombination in the model plant Arabidopsis thaliana. Absence of RAD54 has no detectable effect on meiotic recombination in otherwise wild-type plants but RAD54 becomes essential for meiotic DSB repair in absence of DMC1. In Arabidopsis, dmc1 mutants have an achiasmate meiosis, in which RAD51 repairs meiotic DSBs. Lack of RAD54 leads to meiotic chromosomal fragmentation in absence of DMC1. The action of RAD54 in meiotic RAD51 activity is thus mainly downstream of the role of RAD51 in supporting the activity of DMC1. Equivalent analyses show no effect on meiosis of combining dmc1 with the mutants of the RAD51-mediators RAD51B, RAD51D and XRCC2. RAD54 is thus required for repair of meiotic DSBs by RAD51 and the absence of meiotic phenotype in rad54 plants is a consequence of RAD51 playing a RAD54-independent supporting role to DMC1 in meiotic recombination. Homologous recombination is a universal pathway which repairs broken DNA molecules through the use of homologous DNA templates. It is both essential for maintenance of genome stability and for the generation of genetic diversity through sexual reproduction. A central step of the homologous recombination process is the search for and invasion of a homologous, intact DNA sequence that will be used as template. This key step is catalysed by the RAD51 recombinase in somatic cells and RAD51 and DMC1 in meiotic cells, assisted by a number of associated factors. Among these, the chromatin-remodelling protein RAD54 is a required cofactor for RAD51 in mitotic cells. Understanding of its role during meiotic recombination however remains elusive. We show here that RAD54 is required for repair of meiotic double strand breaks by RAD51 in the plant Arabidopsis thaliana, and this function is downstream of the meiotic role of RAD51 in supporting the activity of DMC1. These results provide new insights into the regulation of the central step of homologous recombination in plants and very probably also other multicellular eukaryotes.
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Affiliation(s)
- Miguel Hernandez Sanchez-Rebato
- Institut Génétique Reproduction et Développement (iGReD), Université Clermont Auvergne, UMR 6293 CNRS, U1103 INSERM, Clermont-Ferrand, France
| | - Alida M Bouatta
- Institut Génétique Reproduction et Développement (iGReD), Université Clermont Auvergne, UMR 6293 CNRS, U1103 INSERM, Clermont-Ferrand, France
| | - Maria E Gallego
- Institut Génétique Reproduction et Développement (iGReD), Université Clermont Auvergne, UMR 6293 CNRS, U1103 INSERM, Clermont-Ferrand, France
| | - Charles I White
- Institut Génétique Reproduction et Développement (iGReD), Université Clermont Auvergne, UMR 6293 CNRS, U1103 INSERM, Clermont-Ferrand, France
| | - Olivier Da Ines
- Institut Génétique Reproduction et Développement (iGReD), Université Clermont Auvergne, UMR 6293 CNRS, U1103 INSERM, Clermont-Ferrand, France
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121
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Wang YY, Chen YK, Lo S, Chi TC, Chen YH, Hu SCS, Chen YW, Jiang SS, Tsai FY, Liu W, Li RN, Hsieh YC, Huang CJ, Yuan SSF. MRE11 promotes oral cancer progression through RUNX2/CXCR4/AKT/FOXA2 signaling in a nuclease-independent manner. Oncogene 2021; 40:3510-3532. [PMID: 33927349 PMCID: PMC8134045 DOI: 10.1038/s41388-021-01698-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 01/28/2021] [Accepted: 02/04/2021] [Indexed: 01/23/2023]
Abstract
MRE11, the nuclease component of RAD50/MRE11/NBS1 DNA repair complex which is essential for repair of DNA double-strand-breaks in normal cells, has recently garnered attention as a critical factor in solid tumor development. Herein we report the crucial role of MRE11 in oral cancer progression in a nuclease-independent manner and delineate its key downstream effectors including CXCR4. MRE11 expression in oral cancer samples was positively associated with tumor size, cancer stage and lymph node metastasis, and was predictive of poorer patient survival and radiotherapy resistance. MRE11 promoted cell proliferation/migration/invasion in a nuclease-independent manner but enhanced radioresistance via a nuclease-dependent pathway. The nuclease independent promotion of EMT and metastasis was mediated by RUNX2, CXCR4, AKT, and FOXA2, while CXCR4 neutralizing antibody mitigated these effects in vitro and in vivo. Collectively, MRE11 may serve as a crucial prognostic factor and therapeutic target in oral cancer, displaying dual nuclease dependent and independent roles that permit separate targeting of tumor vulnerabilities in oral cancer treatment.
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Affiliation(s)
- Yen-Yun Wang
- School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Translational Research Center, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.,Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.,Center for Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yuk-Kwan Chen
- School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Center for Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan.,Division of Oral Pathology & Maxillofacial Radiology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.,Oral & Maxillofacial Imaging Center, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Steven Lo
- College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Tsung-Chen Chi
- Translational Research Center, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Yi-Hua Chen
- Translational Research Center, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Stephen Chu-Sung Hu
- Department of Dermatology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Dermatology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Ya-Wen Chen
- National Institute of Cancer Research, National Health Research Institutes, Miaoli, Taiwan
| | - Shih Sheng Jiang
- National Institute of Cancer Research, National Health Research Institutes, Miaoli, Taiwan
| | - Fang-Yu Tsai
- National Institute of Cancer Research, National Health Research Institutes, Miaoli, Taiwan
| | - Wangta Liu
- Center for Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Biotechnology, College of Life Science, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Ruei-Nian Li
- Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Ya-Ching Hsieh
- Institute of Cancer Sciences, University of Glasgow, Glasgow, UK
| | - Chih-Jen Huang
- Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.,Department of Radiation Oncology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Shyng-Shiou F Yuan
- Translational Research Center, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan. .,Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan. .,Center for Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan. .,Department of Obstetrics and Gynecology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan. .,Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan. .,Department of Biological Science and Technology, College of Biological Science and Technology, National ChiaoTung University, Hsinchu, Taiwan. .,Center For Intelligent Drug Systems and Smart Bio-devices (IDS2B), National Chiao Tung University, Hsinchu, Taiwan.
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122
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Sun X, Liu M, Bai J, Xu J, Zhu C, Dong J, Chen C. ATR kinase activity promotes antibody class switch recombination in B cells through cell cycle regulation without suppressing DSB resection and microhomology usage. J Leukoc Biol 2021; 110:1101-1112. [PMID: 33884660 DOI: 10.1002/jlb.2ma0321-064r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 03/30/2021] [Accepted: 03/31/2021] [Indexed: 12/16/2022] Open
Abstract
Class switch recombination (CSR) changes the effector functions of antibodies and is carried out by classical and alternative nonhomologous end joining (c-NHEJ and A-EJ) of repetitive switch (S) region double-strand breaks (DSBs). The master DNA damage response (DDR) kinase ataxia-telangiectasia mutated (ATM) is critical for CSR in part by suppressing S region DSB resection. However, whether another related DDR kinase ATM- and Rad3-related (ATR) plays similar role in CSR remains elusive. In this study, we investigated the requirement for ATR kinase activity on CSR in both c-NHEJ competent and deficient B cell lines with high-throughput sequencing of S-S junctions. We found that ATR kinase inhibition efficiently blocked both c-NHEJ- and A-EJ-mediated CSR without affecting germline transcription and activation-induced cytosine deaminase expression. In contrast to ATM, ATR does not suppress S region DSB resection and microhomology usage. In addition, ATR kinase inhibition did not affect Cas9-generated DSB end joining by either c-NHEJ and A-EJ. ATR kinase-inhibited stimulated B cells proliferate much slower than controls and exhibited altered cell cycle profile with increased G1 and G2/M phase cells. In summary, our data revealed a role for ATR in promoting both c-NHEJ- and A-EJ-mediated CSR through regulating cell proliferation upon damage without negatively influencing DSB end-joining features.
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Affiliation(s)
- Xikui Sun
- Department of Pediatrics, The Seventh Affiliated Hospital of Sun Yat-Sen University, Zhongshan School of Medicine, Sun Yat-sen University, Shenzhen, Guangdong Province, China.,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Shenzhen, Guangdong Province, China
| | - Meiling Liu
- Department of Pediatrics, The Seventh Affiliated Hospital of Sun Yat-Sen University, Zhongshan School of Medicine, Sun Yat-sen University, Shenzhen, Guangdong Province, China.,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Shenzhen, Guangdong Province, China
| | - Jingning Bai
- Department of Pediatrics, The Seventh Affiliated Hospital of Sun Yat-Sen University, Zhongshan School of Medicine, Sun Yat-sen University, Shenzhen, Guangdong Province, China.,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Shenzhen, Guangdong Province, China
| | - Jiejie Xu
- Department of Pediatrics, The Seventh Affiliated Hospital of Sun Yat-Sen University, Zhongshan School of Medicine, Sun Yat-sen University, Shenzhen, Guangdong Province, China.,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Shenzhen, Guangdong Province, China
| | - Chengming Zhu
- Science Center, the Seventh Affiliated Hospital of Sun Yat-Sen University, Shenzhen, Guangdong Province, China
| | - Junchao Dong
- Department of Pediatrics, The Seventh Affiliated Hospital of Sun Yat-Sen University, Zhongshan School of Medicine, Sun Yat-sen University, Shenzhen, Guangdong Province, China.,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Shenzhen, Guangdong Province, China
| | - Chun Chen
- Department of Pediatrics, The Seventh Affiliated Hospital of Sun Yat-Sen University, Zhongshan School of Medicine, Sun Yat-sen University, Shenzhen, Guangdong Province, China
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123
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DNA2 in Chromosome Stability and Cell Survival-Is It All about Replication Forks? Int J Mol Sci 2021; 22:ijms22083984. [PMID: 33924313 PMCID: PMC8069077 DOI: 10.3390/ijms22083984] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/08/2021] [Accepted: 04/10/2021] [Indexed: 01/16/2023] Open
Abstract
The conserved nuclease-helicase DNA2 has been linked to mitochondrial myopathy, Seckel syndrome, and cancer. Across species, the protein is indispensable for cell proliferation. On the molecular level, DNA2 has been implicated in DNA double-strand break (DSB) repair, checkpoint activation, Okazaki fragment processing (OFP), and telomere homeostasis. More recently, a critical contribution of DNA2 to the replication stress response and recovery of stalled DNA replication forks (RFs) has emerged. Here, we review the available functional and phenotypic data and propose that the major cellular defects associated with DNA2 dysfunction, and the links that exist with human disease, can be rationalized through the fundamental importance of DNA2-dependent RF recovery to genome duplication. Being a crucial player at stalled RFs, DNA2 is a promising target for anti-cancer therapy aimed at eliminating cancer cells by replication-stress overload.
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124
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Pham N, Yan Z, Yu Y, Faria Afreen M, Malkova A, Haber JE, Ira G. Mechanisms restraining break-induced replication at two-ended DNA double-strand breaks. EMBO J 2021; 40:e104847. [PMID: 33844333 DOI: 10.15252/embj.2020104847] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 03/04/2021] [Accepted: 03/09/2021] [Indexed: 11/09/2022] Open
Abstract
DNA synthesis during homologous recombination is highly mutagenic and prone to template switches. Two-ended DNA double-strand breaks (DSBs) are usually repaired by gene conversion with a short patch of DNA synthesis, thus limiting the mutation load to the vicinity of the DSB. Single-ended DSBs are repaired by break-induced replication (BIR), which involves extensive and mutagenic DNA synthesis spanning up to hundreds of kilobases. It remains unknown how mutagenic BIR is suppressed at two-ended DSBs. Here, we demonstrate that BIR is suppressed at two-ended DSBs by proteins coordinating the usage of two ends of a DSB: (i) ssDNA annealing proteins Rad52 and Rad59 that promote second end capture, (ii) D-loop unwinding helicase Mph1, and (iii) Mre11-Rad50-Xrs2 complex that promotes synchronous resection of two ends of a DSB. Finally, BIR is also suppressed when Sir2 silences a normally heterochromatic repair template. All of these proteins are particularly important for limiting BIR when recombination occurs between short repetitive sequences, emphasizing the significance of these mechanisms for species carrying many repetitive elements such as humans.
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Affiliation(s)
- Nhung Pham
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Zhenxin Yan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Yang Yu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Mosammat Faria Afreen
- Department of Biology, Rosenstiel Basic Medical Sciences Research Center, Waltham, MA, USA
| | - Anna Malkova
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | - James E Haber
- Department of Biology, Rosenstiel Basic Medical Sciences Research Center, Waltham, MA, USA
| | - Grzegorz Ira
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
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125
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Murashko MM, Stasevich EM, Schwartz AM, Kuprash DV, Uvarova AN, Demin DE. The Role of RNA in DNA Breaks, Repair and Chromosomal Rearrangements. Biomolecules 2021; 11:biom11040550. [PMID: 33918762 PMCID: PMC8069526 DOI: 10.3390/biom11040550] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 03/31/2021] [Accepted: 04/07/2021] [Indexed: 12/28/2022] Open
Abstract
Incorrect reparation of DNA double-strand breaks (DSB) leading to chromosomal rearrangements is one of oncogenesis's primary causes. Recently published data elucidate the key role of various types of RNA in DSB formation, recognition and repair. With growing interest in RNA biology, increasing RNAs are classified as crucial at the different stages of the main pathways of DSB repair in eukaryotic cells: nonhomologous end joining (NHEJ) and homology-directed repair (HDR). Gene mutations or variation in expression levels of such RNAs can lead to local DNA repair defects, increasing the chromosome aberration frequency. Moreover, it was demonstrated that some RNAs could stimulate long-range chromosomal rearrangements. In this review, we discuss recent evidence demonstrating the role of various RNAs in DSB formation and repair. We also consider how RNA may mediate certain chromosomal rearrangements in a sequence-specific manner.
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Affiliation(s)
- Matvey Mikhailovich Murashko
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; (M.M.M.); (E.M.S.); (A.M.S.); (D.V.K.); (A.N.U.)
| | - Ekaterina Mikhailovna Stasevich
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; (M.M.M.); (E.M.S.); (A.M.S.); (D.V.K.); (A.N.U.)
| | - Anton Markovich Schwartz
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; (M.M.M.); (E.M.S.); (A.M.S.); (D.V.K.); (A.N.U.)
- Moscow Institute of Physics and Technology, Department of Molecular and Biological Physics, 141701 Moscow, Russia
| | - Dmitriy Vladimirovich Kuprash
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; (M.M.M.); (E.M.S.); (A.M.S.); (D.V.K.); (A.N.U.)
| | - Aksinya Nicolaevna Uvarova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; (M.M.M.); (E.M.S.); (A.M.S.); (D.V.K.); (A.N.U.)
| | - Denis Eriksonovich Demin
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; (M.M.M.); (E.M.S.); (A.M.S.); (D.V.K.); (A.N.U.)
- Correspondence:
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126
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Hackley CR. A Novel Set of Cas9 Fusion Proteins to Stimulate Homologous Recombination: Cas9-HRs. CRISPR J 2021; 4:253-263. [PMID: 33876961 DOI: 10.1089/crispr.2020.0034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
CRISPR- Cas9 has revolutionized genetic engineering. However, the inability to control double-strand break (DSB) repair has severely limited both therapeutic and academic applications. Many attempts have been made to control DSB repair choice. However, particularly in the case of larger edits, none have been able to bypass the rate-limiting step of homologous recombination (HR): long-range 5' end resection. Here, we describe a novel set of Cas9 fusions, Cas9-HRs, designed to bypass the rate-limiting step of HR repair by simultaneously coupling initial and long-range end resection. Here, we demonstrate that Cas9-HRs can increase the rate of homology directed repair (HDR) by 2- to 2.5-fold and decrease p53 mediated cellular toxicity by two- to fourfold compared to Cas9 and are functional in multiple mammalian cell lines with minimal apparent editing site bias. These properties should make Cas9-HRs an attractive option for applications demanding increased HDR rates for long inserts and/or reduced p53 pathway activation.
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127
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R-loops as Janus-faced modulators of DNA repair. Nat Cell Biol 2021; 23:305-313. [PMID: 33837288 DOI: 10.1038/s41556-021-00663-4] [Citation(s) in RCA: 92] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/05/2021] [Indexed: 02/01/2023]
Abstract
R-loops are non-B DNA structures with intriguing dual consequences for gene expression and genome stability. In addition to their recognized roles in triggering DNA double-strand breaks (DSBs), R-loops have recently been demonstrated to accumulate in cis to DSBs, especially those induced in transcriptionally active loci. In this Review, we discuss whether R-loops actively participate in DSB repair or are detrimental by-products that must be removed to avoid genome instability.
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128
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Li S, Garay JP, Tubbs CA, Franco HL. CRISPR-based knock-in mutagenesis of the pioneer transcription factor FOXA1: optimization of strategies for multi-allelic proteins in cancer cells. FEBS Open Bio 2021; 11:1537-1551. [PMID: 33666335 PMCID: PMC8167868 DOI: 10.1002/2211-5463.13139] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 02/23/2021] [Accepted: 03/03/2021] [Indexed: 12/24/2022] Open
Abstract
Precise genome engineering of living cells has been revolutionized by the introduction of the highly specific and easily programmable properties of the clustered regularly interspaced short palindromic repeats (CRISPR) technology. This has greatly accelerated research into human health and has facilitated the discovery of novel therapeutics. CRISPR‐Cas9 is most widely employed for its ability to inactivate or knockout specific genes, but can be also used to introduce subtle site‐specific substitutions of DNA sequences that can lead to changes in the amino acid composition of proteins. Despite the proven success of CRISPR‐based knock‐in strategies of genes in typical diploid cells (i.e., cells containing two sets of chromosomes), precise editing of cancer cells, that typically have unstable genomes and multiple copies of chromosomes, is more challenging and not adequately addressed in the literature. Herein, we detail our methodology for replacing endogenous proteins with intended knock‐in mutants in polyploid cancer cells and discuss our experimental design, screening strategy, and facile allele frequency estimation methodology. As proof of principle, we performed genome editing of specific amino acids within the pioneer transcription factor FOXA1, a critical component of estrogen and androgen receptor signaling, in MCF‐7 breast cancer cells. We confirm mutant FOXA1 protein expression and intended amino acid substitutions via western blotting and mass spectrometry. In addition, we show that mutant allele frequency estimation is easily achieved by topoisomerase‐based cloning combined with allele‐specific PCR, which we later confirmed by next‐generation RNA‐sequencing. Typically, there are 4 ‐ 5 copies (alleles) of FOXA1 in breast cancer cells, making the editing of this protein inherently challenging. As a result, most studies that focus on FOXA1 mutants rely on ectopic overexpression of FOXA1 from a plasmid. Therefore, we provide an optimized methodology for replacing endogenous wild‐type FOXA1 with precise knock‐in mutants to enable the systematic analysis of its molecular mechanisms within the appropriate physiological context.
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Affiliation(s)
- Shen Li
- The Lineberger Comprehensive Cancer Center, Department of Genetics, University of North Carolina at Chapel Hill, NC, USA
| | - Joseph P Garay
- The Lineberger Comprehensive Cancer Center, Department of Genetics, University of North Carolina at Chapel Hill, NC, USA
| | - Colby A Tubbs
- The Lineberger Comprehensive Cancer Center, Department of Genetics, University of North Carolina at Chapel Hill, NC, USA
| | - Hector L Franco
- The Lineberger Comprehensive Cancer Center, Department of Genetics, University of North Carolina at Chapel Hill, NC, USA
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129
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Roy U, Kwon Y, Marie L, Symington L, Sung P, Lisby M, Greene EC. The Rad51 paralog complex Rad55-Rad57 acts as a molecular chaperone during homologous recombination. Mol Cell 2021; 81:1043-1057.e8. [PMID: 33421364 PMCID: PMC8262405 DOI: 10.1016/j.molcel.2020.12.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 11/02/2020] [Accepted: 12/10/2020] [Indexed: 12/29/2022]
Abstract
Homologous recombination (HR) is essential for maintenance of genome integrity. Rad51 paralogs fulfill a conserved but undefined role in HR, and their mutations are associated with increased cancer risk in humans. Here, we use single-molecule imaging to reveal that the Saccharomyces cerevisiae Rad51 paralog complex Rad55-Rad57 promotes assembly of Rad51 recombinase filament through transient interactions, providing evidence that it acts like a classical molecular chaperone. Srs2 is an ATP-dependent anti-recombinase that downregulates HR by actively dismantling Rad51 filaments. Contrary to the current model, we find that Rad55-Rad57 does not physically block the movement of Srs2. Instead, Rad55-Rad57 promotes rapid re-assembly of Rad51 filaments after their disruption by Srs2. Our findings support a model in which Rad51 is in flux between free and single-stranded DNA (ssDNA)-bound states, the rate of which is controlled dynamically though the opposing actions of Rad55-Rad57 and Srs2.
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Affiliation(s)
- Upasana Roy
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Youngho Kwon
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Lea Marie
- Department of Microbiology and Immunology, Columbia University, New York, NY 10032, USA
| | - Lorraine Symington
- Department of Microbiology and Immunology, Columbia University, New York, NY 10032, USA
| | - Patrick Sung
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Michael Lisby
- Department of Biology, University of Copenhagen, 2200 Copenhagen N, Denmark; Center for Chromosome Stability, Department of Cellular and Molecular Medicine, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Eric C Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
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130
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Single-molecule analysis reveals cooperative stimulation of Rad51 filament nucleation and growth by mediator proteins. Mol Cell 2021; 81:1058-1073.e7. [PMID: 33421363 PMCID: PMC7941204 DOI: 10.1016/j.molcel.2020.12.020] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 11/02/2020] [Accepted: 12/10/2020] [Indexed: 12/16/2022]
Abstract
Homologous recombination (HR) is an essential DNA double-strand break (DSB) repair mechanism, which is frequently inactivated in cancer. During HR, RAD51 forms nucleoprotein filaments on RPA-coated, resected DNA and catalyzes strand invasion into homologous duplex DNA. How RAD51 displaces RPA and assembles into long HR-proficient filaments remains uncertain. Here, we employed single-molecule imaging to investigate the mechanism of nematode RAD-51 filament growth in the presence of BRC-2 (BRCA2) and RAD-51 paralogs, RFS-1/RIP-1. BRC-2 nucleates RAD-51 on RPA-coated DNA, whereas RFS-1/RIP-1 acts as a "chaperone" to promote 3' to 5' filament growth via highly dynamic engagement with 5' filament ends. Inhibiting ATPase or mutation in the RFS-1 Walker box leads to RFS-1/RIP-1 retention on RAD-51 filaments and hinders growth. The rfs-1 Walker box mutants display sensitivity to DNA damage and accumulate RAD-51 complexes non-functional for HR in vivo. Our work reveals the mechanism of RAD-51 nucleation and filament growth in the presence of recombination mediators.
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131
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Yadav VK, Claeys Bouuaert C. Mechanism and Control of Meiotic DNA Double-Strand Break Formation in S. cerevisiae. Front Cell Dev Biol 2021; 9:642737. [PMID: 33748134 PMCID: PMC7968521 DOI: 10.3389/fcell.2021.642737] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 02/01/2021] [Indexed: 12/17/2022] Open
Abstract
Developmentally programmed formation of DNA double-strand breaks (DSBs) by Spo11 initiates a recombination mechanism that promotes synapsis and the subsequent segregation of homologous chromosomes during meiosis. Although DSBs are induced to high levels in meiosis, their formation and repair are tightly regulated to minimize potentially dangerous consequences for genomic integrity. In S. cerevisiae, nine proteins participate with Spo11 in DSB formation, but their molecular functions have been challenging to define. Here, we describe our current view of the mechanism of meiotic DSB formation based on recent advances in the characterization of the structure and function of DSB proteins and discuss regulatory pathways in the light of recent models.
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Affiliation(s)
| | - Corentin Claeys Bouuaert
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-La-Neuve, Belgium
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132
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Rivero S, Rodríguez-Real G, Marín I, Huertas P. MRGBP, a member of the NuA4 complex, inhibits DNA double-strand break repair. FEBS Open Bio 2021; 11:622-632. [PMID: 33354938 PMCID: PMC7931222 DOI: 10.1002/2211-5463.13071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 11/20/2020] [Accepted: 12/21/2020] [Indexed: 12/15/2022] Open
Abstract
The repair of DNA breaks takes place in the context of chromatin and thus involves the activity of chromatin remodelers. The nucleosome acetyltransferase of H4 (NuA4) remodeler complex enables DNA break repair by relaxing flanking chromatin. Here, we show that MRG domain binding protein (MRGBP), a member of this complex, acts as a general inhibitor of DNA double‐strand break repair. Upon its downregulation, repair is generally increased. This is particularly evident for the stimulation of early events of homologous recombination. Thus, MRGBP has an opposing role to the main catalytic subunits of the NuA4 complex. Our data suggest that MRGBP acts by limiting the activity of this complex in DNA repair, specifically by narrowing the extent of DNA‐end resection.
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Affiliation(s)
- Sabrina Rivero
- Department of Normal and Pathological Histology and Cytology, University of Seville School of Medicine, Spain.,Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Spain
| | - Guillermo Rodríguez-Real
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Spain.,Department of Genetics, University of Seville, Spain
| | - Inés Marín
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Spain
| | - Pablo Huertas
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Spain.,Department of Genetics, University of Seville, Spain
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133
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Sadoughi F, Mirsafaei L, Dana PM, Hallajzadeh J, Asemi Z, Mansournia MA, Montazer M, Hosseinpour M, Yousefi B. The role of DNA damage response in chemo- and radio-resistance of cancer cells: Can DDR inhibitors sole the problem? DNA Repair (Amst) 2021; 101:103074. [PMID: 33640757 DOI: 10.1016/j.dnarep.2021.103074] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 02/12/2021] [Indexed: 12/15/2022]
Abstract
Up to now, many improvements have been made in providing more therapeutic strategies for cancer patients. The lack of susceptibility to common therapies like chemo- and radio-therapy is one of the reasons why we need more methods in the field of cancer therapy. DNA damage response (DDR) is a set of mechanisms which identifies DNA lesions and triggers the repair process for restoring DNA after causing an arrest in the cell cycle. The ability of DDR in maintaining the genome stability and integrity can be favorable to cancerous cells which are exposed to radiation therapy or are treated with chemotherapeutic agents. When DDR mechanisms are error-free in cancer cells, they can escape the expected cellular death and display resistance to treatment. In this regard, targeting different components of DDR can help to increase the susceptibility of advanced tumors to chemo- and radio-therapy.
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Affiliation(s)
- Fatemeh Sadoughi
- Research Center for Biochemistry and Nutrition in Metabolic Diseases, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran.
| | - Liaosadat Mirsafaei
- Department of Cardiology, Ramsar Campus, Mazandaran University of Medical Sciences, Sari, Iran.
| | - Parisa Maleki Dana
- Research Center for Biochemistry and Nutrition in Metabolic Diseases, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran.
| | - Jamal Hallajzadeh
- Department of Biochemistry and Nutrition, Research Center for Evidence-Based Health Management, Maragheh University of Medical Sciences, Maragheh, Iran.
| | - Zatollah Asemi
- Research Center for Biochemistry and Nutrition in Metabolic Diseases, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran.
| | - Mohammad Ali Mansournia
- Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
| | - Majid Montazer
- Department of Thorax Surgery, Tuberculosis and Lung Disease Research Center, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
| | - Mohammad Hosseinpour
- Molecular Medicine Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
| | - Bahman Yousefi
- Molecular Medicine Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; Department of Biochemistry, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
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134
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Biernacka A, Skrzypczak M, Zhu Y, Pasero P, Rowicka M, Ginalski K. High-resolution, ultrasensitive and quantitative DNA double-strand break labeling in eukaryotic cells using i-BLESS. Nat Protoc 2021; 16:1034-1061. [PMID: 33349705 PMCID: PMC8088906 DOI: 10.1038/s41596-020-00448-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 10/09/2020] [Indexed: 11/09/2022]
Abstract
DNA double-strand breaks (DSBs) are implicated in various physiological processes, such as class-switch recombination or crossing-over during meiosis, but also present a threat to genome stability. Extensive evidence shows that DSBs are a primary source of chromosome translocations or deletions, making them a major cause of genomic instability, a driving force of many diseases of civilization, such as cancer. Therefore, there is a great need for a precise, sensitive, and universal method for DSB detection, to enable both the study of their mechanisms of formation and repair as well as to explore their therapeutic potential. We provide a detailed protocol for our recently developed ultrasensitive and genome-wide DSB detection method: immobilized direct in situ breaks labeling, enrichment on streptavidin and next-generation sequencing (i-BLESS), which relies on the encapsulation of cells in agarose beads and labeling breaks directly and specifically with biotinylated linkers. i-BLESS labels DSBs with single-nucleotide resolution, allows detection of ultrarare breaks, takes 5 d to complete, and can be applied to samples from any organism, as long as a sufficient amount of starting material can be obtained. We also describe how to combine i-BLESS with our qDSB-Seq approach to enable the measurement of absolute DSB frequencies per cell and their precise genomic coordinates at the same time. Such normalization using qDSB-Seq is especially useful for the evaluation of spontaneous DSB levels and the estimation of DNA damage induced rather uniformly in the genome (e.g., by irradiation or radiomimetic chemotherapeutics).
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Affiliation(s)
- Anna Biernacka
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Warsaw, Poland
| | - Magdalena Skrzypczak
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Warsaw, Poland
| | - Yingjie Zhu
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, TX, USA
| | - Philippe Pasero
- Institut de Génétique Humaine, CNRS et Université de Montpellier, Montpellier, France
| | - Maga Rowicka
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, TX, USA
- Institute for Translational Sciences, University of Texas Medical Branch at Galveston, Galveston, TX, USA
- Sealy Center for Molecular Medicine, University of Texas Medical Branch at Galveston, Galveston, TX, USA
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch at Galveston, Galveston, TX, USA
| | - Krzysztof Ginalski
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Warsaw, Poland.
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135
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Locke AJ, Hossain L, McCrostie G, Ronato DA, Fitieh A, Rafique T, Mashayekhi F, Motamedi M, Masson JY, Ismail I. SUMOylation mediates CtIP's functions in DNA end resection and replication fork protection. Nucleic Acids Res 2021; 49:928-953. [PMID: 33406258 PMCID: PMC7826263 DOI: 10.1093/nar/gkaa1232] [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: 12/09/2019] [Revised: 12/03/2020] [Accepted: 12/09/2020] [Indexed: 12/13/2022] Open
Abstract
Double-strand breaks and stalled replication forks are a significant threat to genomic stability that can lead to chromosomal rearrangements or cell death. The protein CtIP promotes DNA end resection, an early step in homologous recombination repair, and has been found to protect perturbed forks from excessive nucleolytic degradation. However, it remains unknown how CtIP's function in fork protection is regulated. Here, we show that CtIP recruitment to sites of DNA damage and replication stress is impaired upon global inhibition of SUMOylation. We demonstrate that CtIP is a target for modification by SUMO-2 and that this occurs constitutively during S phase. The modification is dependent on the activities of cyclin-dependent kinases and the PI-3-kinase-related kinase ATR on CtIP's carboxyl-terminal region, an interaction with the replication factor PCNA, and the E3 SUMO ligase PIAS4. We also identify residue K578 as a key residue that contributes to CtIP SUMOylation. Functionally, a CtIP mutant where K578 is substituted with a non-SUMOylatable arginine residue is defective in promoting DNA end resection, homologous recombination, and in protecting stalled replication forks from excessive nucleolytic degradation. Our results shed further light on the tightly coordinated regulation of CtIP by SUMOylation in the maintenance of genome stability.
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Affiliation(s)
- Andrew J Locke
- Division of Experimental Oncology, Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta; Cross Cancer Institute, Edmonton, Alberta, T6G 1Z2, Canada
| | - Lazina Hossain
- Division of Experimental Oncology, Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta; Cross Cancer Institute, Edmonton, Alberta, T6G 1Z2, Canada
| | - Glynnis McCrostie
- Division of Experimental Oncology, Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta; Cross Cancer Institute, Edmonton, Alberta, T6G 1Z2, Canada
| | - Daryl A Ronato
- Oncology Division, CHU de Québec-Université Laval Research Center, Québec City, Québec, G1R 3S3, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine; Laval University Cancer Research Center, Université Laval, Québec City, Québec, G1V 0A6, Canada
| | - Amira Fitieh
- Division of Experimental Oncology, Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta; Cross Cancer Institute, Edmonton, Alberta, T6G 1Z2, Canada
- Biophysics Department, Faculty of Science, Cairo University, Giza, Egypt
| | - Tanzeem Ahmed Rafique
- Division of Experimental Oncology, Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta; Cross Cancer Institute, Edmonton, Alberta, T6G 1Z2, Canada
| | - Fatemeh Mashayekhi
- Division of Experimental Oncology, Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta; Cross Cancer Institute, Edmonton, Alberta, T6G 1Z2, Canada
| | - Mobina Motamedi
- Division of Experimental Oncology, Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta; Cross Cancer Institute, Edmonton, Alberta, T6G 1Z2, Canada
| | - Jean-Yves Masson
- Oncology Division, CHU de Québec-Université Laval Research Center, Québec City, Québec, G1R 3S3, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine; Laval University Cancer Research Center, Université Laval, Québec City, Québec, G1V 0A6, Canada
| | - Ismail Hassan Ismail
- Division of Experimental Oncology, Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta; Cross Cancer Institute, Edmonton, Alberta, T6G 1Z2, Canada
- Biophysics Department, Faculty of Science, Cairo University, Giza, Egypt
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136
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Shen W, Ma Y, Qi H, Wang W, He J, Xiao F, Zhu H, He S. Kinetics model of DNA double-strand break repair in eukaryotes. DNA Repair (Amst) 2021; 100:103035. [PMID: 33618125 DOI: 10.1016/j.dnarep.2020.103035] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 12/11/2020] [Indexed: 11/26/2022]
Abstract
This manuscript outlines the kinetics of two main repair pathways of DNA double-strand break (DSB) in eukaryotes: non-homologous end joining (NHEJ) and homologous recombination repair (HRR). In this review, we discuss the precise study of recruitment kinetics of repair proteins based on the latest technologies in the past two decades. Then we simulate the theoretical description of the DNA repair process by mathematical models. In our study, the consecutive reactions chain (CRC) model and continuous-time random walk (CTRW) model have been unified by us, so that we can obtain the function of the number of intermediates with time in the same framework of equations, overcome the incompatibility between the two models. On this basis, we propose a data fitting workflow using these both models. Finally, we give an overview of different real-time quantitative methods and the new mechanism complexity that can be found from the corresponding dynamic models.
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Affiliation(s)
- Wangtao Shen
- Institute of Biochemistry and Molecular Biology, Hengyang Medical College, University of South China, Hengyang, 421001, China
| | - Yun Ma
- Institute of Biochemistry and Molecular Biology, Hengyang Medical College, University of South China, Hengyang, 421001, China.
| | - Huizhou Qi
- Institute of Biochemistry and Molecular Biology, Hengyang Medical College, University of South China, Hengyang, 421001, China; Function Laboratory Center, Hengyang Medical College, University of South China, Hengyang, 421001, China; Hengyang Key Laboratory for Biological Effects of Nuclear Radiation, University of South China, Hengyang, 421001, China
| | - Wuzhou Wang
- Institute of Biochemistry and Molecular Biology, Hengyang Medical College, University of South China, Hengyang, 421001, China; Hengyang Key Laboratory for Biological Effects of Nuclear Radiation, University of South China, Hengyang, 421001, China
| | - Junyan He
- Department of Radiation Oncology, The First Affiliated Hospital of University of South China, Hengyang, 421001, China
| | - Fangzhu Xiao
- Hengyang Key Laboratory for Biological Effects of Nuclear Radiation, University of South China, Hengyang, 421001, China
| | - Hui Zhu
- Institute of Engineering Mathematics, Mathematics and Physics College, University of South China, Hengyang, 421001, China
| | - Shuya He
- Institute of Biochemistry and Molecular Biology, Hengyang Medical College, University of South China, Hengyang, 421001, China; Hengyang Key Laboratory for Biological Effects of Nuclear Radiation, University of South China, Hengyang, 421001, China.
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137
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Sharma S, Anand R, Zhang X, Francia S, Michelini F, Galbiati A, Williams H, Ronato DA, Masson JY, Rothenberg E, Cejka P, d'Adda di Fagagna F. MRE11-RAD50-NBS1 Complex Is Sufficient to Promote Transcription by RNA Polymerase II at Double-Strand Breaks by Melting DNA Ends. Cell Rep 2021; 34:108565. [PMID: 33406426 PMCID: PMC7788559 DOI: 10.1016/j.celrep.2020.108565] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 08/19/2020] [Accepted: 12/07/2020] [Indexed: 12/24/2022] Open
Abstract
The MRE11-RAD50-NBS1 (MRN) complex supports the synthesis of damage-induced long non-coding RNA (dilncRNA) by RNA polymerase II (RNAPII) from DNA double-strand breaks (DSBs) by an unknown mechanism. Here, we show that recombinant human MRN and native RNAPII are sufficient to reconstitute a minimal functional transcriptional apparatus at DSBs. MRN recruits and stabilizes RNAPII at DSBs. Unexpectedly, transcription is promoted independently from MRN nuclease activities. Rather, transcription depends on the ability of MRN to melt DNA ends, as shown by the use of MRN mutants and specific allosteric inhibitors. Single-molecule FRET assays with wild-type and mutant MRN show a tight correlation between the ability to melt DNA ends and to promote transcription. The addition of RPA enhances MRN-mediated transcription, and unpaired DNA ends allow MRN-independent transcription by RNAPII. These results support a model in which MRN generates single-strand DNA ends that favor the initiation of transcription by RNAPII.
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Affiliation(s)
- Sheetal Sharma
- IFOM-The FIRC Institute of Molecular Oncology, Milan 20139, Italy; Department of Experimental Medicine and Biotechnology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
| | - Roopesh Anand
- Institute for Research in Biomedicine, Università della Svizzera Italiana (USI), Faculty of Biomedical Sciences, Bellinzona 6500, Switzerland
| | - Xuzhu Zhang
- NYU Langone Medical Center, 450 East 29th Street, New York, NY, USA
| | - Sofia Francia
- IFOM-The FIRC Institute of Molecular Oncology, Milan 20139, Italy; Istituto di Genetica Molecolare, CNR-Consiglio Nazionale delle Ricerche, Pavia 2700, Italy
| | - Flavia Michelini
- IFOM-The FIRC Institute of Molecular Oncology, Milan 20139, Italy
| | | | | | - Daryl A Ronato
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, 9 McMahon, Québec City, QC G1R 2J6, Canada; Department of Molecular Biology, Medical Biochemistry, and Pathology, Laval University Cancer Research Center, Québec City, QC G1R 2J6, Canada
| | - Jean-Yves Masson
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, 9 McMahon, Québec City, QC G1R 2J6, Canada; Department of Molecular Biology, Medical Biochemistry, and Pathology, Laval University Cancer Research Center, Québec City, QC G1R 2J6, Canada
| | - Eli Rothenberg
- NYU Langone Medical Center, 450 East 29th Street, New York, NY, USA
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera Italiana (USI), Faculty of Biomedical Sciences, Bellinzona 6500, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich 8093, Switzerland.
| | - Fabrizio d'Adda di Fagagna
- IFOM-The FIRC Institute of Molecular Oncology, Milan 20139, Italy; Istituto di Genetica Molecolare, CNR-Consiglio Nazionale delle Ricerche, Pavia 2700, Italy.
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138
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Lee KY, Dutta A. Chk1 promotes non-homologous end joining in G1 through direct phosphorylation of ASF1A. Cell Rep 2021; 34:108680. [PMID: 33503415 DOI: 10.1016/j.celrep.2020.108680] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 11/16/2020] [Accepted: 12/30/2020] [Indexed: 12/13/2022] Open
Abstract
The cell-cycle phase is a major determinant of repair pathway choice at DNA double strand breaks, non-homologous end joining (NHEJ), or homologous recombination (HR). Chk1 responds to genotoxic stress in S/G2 phase, but here, we report a role of Chk1 in directly promoting NHEJ repair in G1 phase. ASF1A is a histone chaperone, but it promotes NHEJ through a pathway independent of its histone-chaperone activity. Chk1 activated by ataxia telangiectasia mutated (ATM) kinase on DNA breaks in G1 promotes NHEJ through direct phosphorylation of ASF1A at Ser-166. ASF1A phosphorylated at Ser-166 interacts with the repair protein MDC1 and thus enhances MDC1's interaction with ATM and the stable localization of ATM at DNA breaks. Chk1 deficiency suppresses all steps downstream of MDC1 following a DNA break in G1, namely histone ubiquitination, 53BP1 localization to the DNA break, and NHEJ. Thus, ASF1A phosphorylation by Chk1 is essential for DNA break repair by NHEJ in G1.
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Affiliation(s)
- Kyung Yong Lee
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22901, USA; Division of Cancer Biology, Research Institute, National Cancer Center, Goyang-si, Gyeonggi-do 10408, South Korea
| | - Anindya Dutta
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22901, USA.
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139
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Anglada T, Genescà A, Martín M. Age-associated deficient recruitment of 53BP1 in G1 cells directs DNA double-strand break repair to BRCA1/CtIP-mediated DNA-end resection. Aging (Albany NY) 2020; 12:24872-24893. [PMID: 33361520 PMCID: PMC7803562 DOI: 10.18632/aging.202419] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 12/03/2020] [Indexed: 02/06/2023]
Abstract
DNA repair mechanisms play a crucial role in maintaining genome integrity. However, the increased frequency of DNA double-strand breaks (DSBs) and genome rearrangements in aged individuals suggests an age-associated DNA repair deficiency. Previous work from our group revealed a delayed firing of the DNA damage response in human mammary epithelial cells (HMECs) from aged donors. We now report a decreased activity of the main DSB repair pathways, the canonical non-homologous end-joining (c-NHEJ) and the homologous recombination (HR) in these HMECs from older individuals. We describe here a deficient recruitment of 53BP1 to DSB sites in G1 cells, probably influenced by an altered epigenetic regulation. 53BP1 absence at some DSBs is responsible for the age-associated DNA repair defect, as it permits the ectopic formation of BRCA1 foci while still in the G1 phase. CtIP and RPA foci are also formed in G1 cells from aged donors, but RAD51 is not recruited, thus indicating that extensive DNA-end resection occurs in these breaks although HR is not triggered. These results suggest an age-associated switch of DSB repair from canonical to highly mutagenic alternative mechanisms that promote the formation of genome rearrangements, a source of genome instability that might contribute to the aging process.
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Affiliation(s)
- Teresa Anglada
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| | - Anna Genescà
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| | - Marta Martín
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
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140
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Zabolotnaya E, Mela I, Henderson RM, Robinson NP. Turning the Mre11/Rad50 DNA repair complex on its head: lessons from SMC protein hinges, dynamic coiled-coil movements and DNA loop-extrusion? Biochem Soc Trans 2020; 48:2359-2376. [PMID: 33300987 PMCID: PMC7752040 DOI: 10.1042/bst20170168] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 10/19/2020] [Accepted: 10/22/2020] [Indexed: 12/12/2022]
Abstract
The bacterial SbcC/SbcD DNA repair proteins were identified over a quarter of a century ago. Following the subsequent identification of the homologous Mre11/Rad50 complex in the eukaryotes and archaea, it has become clear that this conserved chromosomal processing machinery is central to DNA repair pathways and the maintenance of genomic stability in all forms of life. A number of experimental studies have explored this intriguing genome surveillance machinery, yielding significant insights and providing conceptual advances towards our understanding of how this complex operates to mediate DNA repair. However, the inherent complexity and dynamic nature of this chromosome-manipulating machinery continue to obfuscate experimental interrogations, and details regarding the precise mechanisms that underpin the critical repair events remain unanswered. This review will summarize our current understanding of the dramatic structural changes that occur in Mre11/Rad50 complex to mediate chromosomal tethering and accomplish the associated DNA processing events. In addition, undetermined mechanistic aspects of the DNA enzymatic pathways driven by this vital yet enigmatic chromosomal surveillance and repair apparatus will be discussed. In particular, novel and putative models of DNA damage recognition will be considered and comparisons will be made between the modes of action of the Rad50 protein and other related ATPases of the overarching SMC superfamily.
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Affiliation(s)
| | - Ioanna Mela
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, U.K
| | | | - Nicholas P. Robinson
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster LA1 4YG, U.K
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141
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Guttery DS, Ramaprasad A, Ferguson DJP, Zeeshan M, Pandey R, Brady D, Holder AA, Pain A, Tewari R. MRE11 Is Crucial for Malaria Parasite Transmission and Its Absence Affects Expression of Interconnected Networks of Key Genes Essential for Life. Cells 2020; 9:E2590. [PMID: 33287434 PMCID: PMC7761864 DOI: 10.3390/cells9122590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 11/30/2020] [Accepted: 12/01/2020] [Indexed: 11/16/2022] Open
Abstract
The meiotic recombination 11 protein (MRE11) plays a key role in DNA damage response and maintenance of genome stability. However, little is known about its function during development of the malaria parasite Plasmodium. Here, we present a functional, ultrastructural and transcriptomic analysis of Plasmodium parasites lacking MRE11 during its life cycle in both mammalian and mosquito vector hosts. Genetic disruption of Plasmodium berghei mre11 (PbMRE11) results in significant retardation of oocyst development in the mosquito midgut associated with cytoplasmic and nuclear degeneration, along with concomitant ablation of sporogony and subsequent parasite transmission. Further, absence of PbMRE11 results in significant transcriptional downregulation of genes involved in key interconnected biological processes that are fundamental to all eukaryotic life including ribonucleoprotein biogenesis, spliceosome function and iron-sulfur cluster assembly. Overall, our study provides a comprehensive functional analysis of MRE11's role in Plasmodium development during the mosquito stages and offers a potential target for therapeutic intervention during malaria parasite transmission.
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Affiliation(s)
- David S. Guttery
- Queens Medical Centre, School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK; (M.Z.); (R.P.); (D.B.)
| | - Abhinay Ramaprasad
- Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia; (A.R.); (A.P.)
- The Francis Crick Institute, London NW1 1AT, UK;
| | - David J. P. Ferguson
- Nuffield Department of Clinical Laboratory Science, University of Oxford, John Radcliffe Hospital, Oxford OX1 2JD, UK;
- Department Biological & Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Mohammad Zeeshan
- Queens Medical Centre, School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK; (M.Z.); (R.P.); (D.B.)
| | - Rajan Pandey
- Queens Medical Centre, School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK; (M.Z.); (R.P.); (D.B.)
| | - Declan Brady
- Queens Medical Centre, School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK; (M.Z.); (R.P.); (D.B.)
| | | | - Arnab Pain
- Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia; (A.R.); (A.P.)
- Nuffield Department of Clinical Laboratory Science, University of Oxford, John Radcliffe Hospital, Oxford OX1 2JD, UK;
- Research Center for Zoonosis Control, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo 060-0808, Japan
| | - Rita Tewari
- Queens Medical Centre, School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK; (M.Z.); (R.P.); (D.B.)
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142
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Saha T, Sundaravinayagam D, Di Virgilio M. Charting a DNA Repair Roadmap for Immunoglobulin Class Switch Recombination. Trends Biochem Sci 2020; 46:184-199. [PMID: 33250286 DOI: 10.1016/j.tibs.2020.10.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 10/08/2020] [Accepted: 10/23/2020] [Indexed: 01/18/2023]
Abstract
Immunoglobulin (Ig) class switch recombination (CSR) is the process occurring in mature B cells that diversifies the effector component of antibody responses. CSR is initiated by the activity of the B cell-specific enzyme activation-induced cytidine deaminase (AID), which leads to the formation of programmed DNA double-strand breaks (DSBs) at the Ig heavy chain (Igh) locus. Mature B cells use a multilayered and complex regulatory framework to ensure that AID-induced DNA breaks are channeled into productive repair reactions leading to CSR, and to avoid aberrant repair events causing lymphomagenic chromosomal translocations. Here, we review the DNA repair pathways acting on AID-induced DSBs and their functional interplay, with a particular focus on the latest developments in their molecular composition and mechanistic regulation.
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Affiliation(s)
- Tannishtha Saha
- Laboratory of Genome Diversification and Integrity, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 13125, Germany
| | - Devakumar Sundaravinayagam
- Laboratory of Genome Diversification and Integrity, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 13125, Germany.
| | - Michela Di Virgilio
- Laboratory of Genome Diversification and Integrity, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 13125, Germany; Charité-Universitätsmedizin Berlin, Berlin 10117, Germany.
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143
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Waisertreiger I, Barlow J. Fragile site instability: measuring more than breaks. Oncoscience 2020; 7:60-67. [PMID: 33195735 PMCID: PMC7640903 DOI: 10.18632/oncoscience.513] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 05/17/2020] [Indexed: 12/23/2022] Open
Abstract
Genome instability is not only a hallmark of cancer, it is necessary for its initiation and evolution, and naturally accumulates as cells age. Replication stress is a potent source of genome instability found in many tumor types [1]. Chromosomal fragile sites are genomic loci highly prone to DNA damage specifically from replication stress and are frequently mutated in cancer [2-4]2-4]. While tracking the origin of individual mutations has proved challenging, measuring DNA damage and repair at endogenous sites can offer key insights into understanding the etiology of cancer. In the past 15 years, the causal link between replication stress, oncogene activation, and tumor initiation and evolution has become increasingly clear [1, 5-9]. Replication-associated damage accumulates at early stages of tumorigenesis and may promote further transformation. Studying the causes and consequences of fragile site instability can offer a window into the earliest stages of carcinogenesis [10-13]. In particular, fragile site studies will help us understand the molecular underpinnings influencing the frequency of DNA breakage, successful repair processes suppressing genome instability, and unsuccessful repair leading to mutations and chromosome rearrangements. Of these, measuring successful repair is the most challenging as it leaves little evidence behind.
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Affiliation(s)
- Irina Waisertreiger
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA, USA
| | - Jacqueline Barlow
- Department of Microbiology and Molecular Genetics & Genome Center, University of California, Davis, CA, USA
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144
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Grandin N, Gallego ME, White CI, Charbonneau M. Inhibition of the alternative lengthening of telomeres pathway by subtelomeric sequences in Saccharomyces cerevisiae. DNA Repair (Amst) 2020; 96:102996. [PMID: 33126043 DOI: 10.1016/j.dnarep.2020.102996] [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: 06/05/2020] [Revised: 09/24/2020] [Accepted: 10/04/2020] [Indexed: 10/23/2022]
Abstract
In the budding yeast Saccharomyces cerevisiae, telomerase is constitutively active and is essential for chromosome end protection and illimited proliferation of cell populations. However, upon inactivation of telomerase, alternative mechanims of telomere maintenance allow proliferation of only extremely rare survivors. S. cerevisiae type I and type II survivors differ by the nature of the donor sequences used for repair by homologous recombination of the uncapped terminal TG1-3 telomeric sequences. Type I amplifies the subtelomeric Y' sequences and is more efficient than type II, which amplifies the terminal TG1-3 repeats. However, type II survivors grow faster than type I survivors and can easily outgrow them in liquid cultures. The mechanistic interest of studying S. cerevisiae telomeric recombination is reinforced by the fact that type II recombination is the equivalent of the alternative lengthening of telomeres (ALT) pathway that is used by 5-15 % of cancer types as an alternative to telomerase reactivation. In budding yeast, only around half of the 32 telomeres harbor Y' subtelomeric elements. We report here that in strains harboring Y' elements on all telomeres, type II survivors are not observed, most likely due to an increase in the efficiency of type I recombination. However, in a temperature-sensitive cdc13-1 mutant grown at semi-permissive temperature, the increased amount of telomeric TG1-3 repeats could overcome type II inhibition by the subtelomeric Y' sequences. Strikingly, in the 100 % Y' strain the replicative senescence crisis normally provoked by inactivation of telomerase completely disappeared and the severity of the crisis was proportional to the percentage of chromosome-ends lacking Y' subtelomeric sequences. The present study highlights the fact that the nature of subtelomeric elements can influence the selection of the pathway of telomere maintenance by recombination, as well as the response of the cell to telomeric damage caused by telomerase inactivation.
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Affiliation(s)
- Nathalie Grandin
- GReD Institute, CNRS UMR6293, INSERM U1103, Faculty of Medicine, University Clermont-Auvergne, 28 place Henri Dunant, BP 38, 63001 Clermont-Ferrand Cedex, France
| | - Maria Eugenia Gallego
- GReD Institute, CNRS UMR6293, INSERM U1103, Faculty of Medicine, University Clermont-Auvergne, 28 place Henri Dunant, BP 38, 63001 Clermont-Ferrand Cedex, France
| | - Charles I White
- GReD Institute, CNRS UMR6293, INSERM U1103, Faculty of Medicine, University Clermont-Auvergne, 28 place Henri Dunant, BP 38, 63001 Clermont-Ferrand Cedex, France
| | - Michel Charbonneau
- GReD Institute, CNRS UMR6293, INSERM U1103, Faculty of Medicine, University Clermont-Auvergne, 28 place Henri Dunant, BP 38, 63001 Clermont-Ferrand Cedex, France.
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145
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Zhao F, Kim W, Kloeber JA, Lou Z. DNA end resection and its role in DNA replication and DSB repair choice in mammalian cells. Exp Mol Med 2020; 52:1705-1714. [PMID: 33122806 PMCID: PMC8080561 DOI: 10.1038/s12276-020-00519-1] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/29/2020] [Accepted: 09/09/2020] [Indexed: 12/19/2022] Open
Abstract
DNA end resection has a key role in double-strand break repair and DNA replication. Defective DNA end resection can cause malfunctions in DNA repair and replication, leading to greater genomic instability. DNA end resection is initiated by MRN-CtIP generating short, 3′-single-stranded DNA (ssDNA). This newly generated ssDNA is further elongated by multiple nucleases and DNA helicases, such as EXO1, DNA2, and BLM. Effective DNA end resection is essential for error-free homologous recombination DNA repair, the degradation of incorrectly replicated DNA and double-strand break repair choice. Because of its importance in DNA repair, DNA end resection is strictly regulated. Numerous mechanisms have been reported to regulate the initiation, extension, and termination of DNA end resection. Here, we review the general process of DNA end resection and its role in DNA replication and repair pathway choice. Carefully regulated enzymatic processing of the ends of DNA strands is essential for efficient replication and damage repair while also minimizing the risk of genomic instability. Replication and repair depend on a mechanism known as DNA resection, in which enzymes trim back double-stranded DNA ends to leave single-stranded overhangs. Zhenkun Lou and colleagues at the Mayo Clinic in Rochester, USA, have reviewed the various steps involved in the initiation and control of DNA resection. There are multiple different DNA repair processes, and the manner in which resection occurs can determine which of these processes subsequently takes place. The authors note that cancer cells rely heavily on these repair pathways to survive radiotherapy and chemotherapy, and highlight research opportunities that might reveal therapeutically useful vulnerabilities in the resection mechanism.
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Affiliation(s)
- Fei Zhao
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Wootae Kim
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Jake A Kloeber
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA.,Mayo Clinic Medical Scientist Training Program, Mayo Clinic, Rochester, MN, 55905, USA.,Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA
| | - Zhenkun Lou
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA.
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146
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USP52 regulates DNA end resection and chemosensitivity through removing inhibitory ubiquitination from CtIP. Nat Commun 2020; 11:5362. [PMID: 33097710 PMCID: PMC7584643 DOI: 10.1038/s41467-020-19202-0] [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: 02/25/2020] [Accepted: 09/28/2020] [Indexed: 02/07/2023] Open
Abstract
Human C-terminal binding protein (CtBP)–interacting protein (CtIP) is a central regulator to initiate DNA end resection and homologous recombination (HR). Several studies have shown that post-translational modifications control the activity or expression of CtIP. However, it remains unclear whether and how cells restrain CtIP activity in unstressed cells and activate CtIP when needed. Here, we identify that USP52 directly interacts with and deubiquitinates CtIP, thereby promoting DNA end resection and HR. Mechanistically, USP52 removes the ubiquitination of CtIP to facilitate the phosphorylation and activation of CtIP at Thr-847. In addition, USP52 is phosphorylated by ATM at Ser-1003 after DNA damage, which enhances the catalytic activity of USP52. Furthermore, depletion of USP52 sensitizes cells to PARP inhibition in a CtIP-dependent manner in vitro and in vivo. Collectively, our findings reveal the key role of USP52 and the regulatory complexity of CtIP deubiquitination in DNA repair. C-terminal binding protein (CtBP) interacting protein (CtIP) is a fundamental factor for the initiation of DNA end resection to initiate DNA repair. Here the authors reveal mechanistic insights into the regulation of CtIP via the deubiquitinase USP52.
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147
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Crickard JB, Kwon Y, Sung P, Greene EC. Rad54 and Rdh54 occupy spatially and functionally distinct sites within the Rad51-ssDNA presynaptic complex. EMBO J 2020; 39:e105705. [PMID: 32790929 PMCID: PMC7560196 DOI: 10.15252/embj.2020105705] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/13/2020] [Accepted: 07/29/2020] [Indexed: 12/21/2022] Open
Abstract
Rad54 and Rdh54 are closely related ATP-dependent motor proteins that participate in homologous recombination (HR). During HR, these enzymes functionally interact with the Rad51 presynaptic complex (PSC). Despite their importance, we know little about how they are organized within the PSC, or how their organization affects PSC function. Here, we use single-molecule optical microscopy and genetic analysis of chimeric protein constructs to evaluate the binding distributions of Rad54 and Rdh54 within the PSC. We find that Rad54 and Rdh54 have distinct binding sites within the PSC, which allow these proteins to act cooperatively as DNA sequences are aligned during homology search. Our data also reveal that Rad54 must bind to a specific location within the PSC, whereas Rdh54 retains its function in the repair of MMS-induced DNA damage even when recruited to the incorrect location. These findings support a model in which the relative binding sites of Rad54 and Rdh54 help to define their functions during mitotic HR.
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Affiliation(s)
- J Brooks Crickard
- Department of Biochemistry & Molecular BiophysicsColumbia UniversityNew YorkNYUSA
| | - Youngho Kwon
- Department of Biochemistry and Structural BiologyUniversity of Texas Health Science Center at San AntonioSan AntonioTXUSA
| | - Patrick Sung
- Department of Biochemistry and Structural BiologyUniversity of Texas Health Science Center at San AntonioSan AntonioTXUSA
| | - Eric C Greene
- Department of Biochemistry & Molecular BiophysicsColumbia UniversityNew YorkNYUSA
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148
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p31 comet promotes homologous recombination by inactivating REV7 through the TRIP13 ATPase. Proc Natl Acad Sci U S A 2020; 117:26795-26803. [PMID: 33051298 PMCID: PMC7604461 DOI: 10.1073/pnas.2008830117] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The repair of DNA double strand breaks (DSBs) that arise from external mutagenic agents and routine cellular processes is essential for life. DSBs are repaired by two major pathways, homologous recombination (HR) and classical nonhomologous end joining (C-NHEJ). DSB repair pathway choice is largely dictated at the step of 5'-3' DNA end resection, which is promoted during S phase, in part by BRCA1. Opposing end resection is the 53BP1 protein, which recruits the ssDNA-binding REV7-Shieldin complex to favor C-NHEJ repair. We recently identified TRIP13 as a proresection factor that remodels REV7, causing its dissociation from the Shieldin subunit SHLD3. Here, we identify p31comet, a negative regulator of MAD2 and the spindle assembly checkpoint, as an important mediator of the TRIP13-REV7 interaction. p31comet binds to the REV7-Shieldin complex in cells, promotes REV7 inactivation, and causes PARP inhibitor resistance. p31comet also participates in the extraction of REV7 from the chromatin. Furthermore, p31comet can counteract REV7 function in translesion synthesis (TLS) by releasing it from REV3 in the Pol ζ complex. Finally, p31comet, like TRIP13, is overexpressed in many cancers and this correlates with poor prognosis. Thus, we reveal a key player in the regulation of HR and TLS with significant clinical implications.
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149
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Gallagher DN, Pham N, Tsai AM, Janto NV, Choi J, Ira G, Haber JE. A Rad51-independent pathway promotes single-strand template repair in gene editing. PLoS Genet 2020; 16:e1008689. [PMID: 33057349 PMCID: PMC7591047 DOI: 10.1371/journal.pgen.1008689] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 10/27/2020] [Accepted: 08/03/2020] [Indexed: 01/26/2023] Open
Abstract
The Rad51/RecA family of recombinases perform a critical function in typical repair of double-strand breaks (DSBs): strand invasion of a resected DSB end into a homologous double-stranded DNA (dsDNA) template sequence to initiate repair. However, repair of a DSB using single stranded DNA (ssDNA) as a template, a common method of CRISPR/Cas9-mediated gene editing, is Rad51-independent. We have analyzed the genetic requirements for these Rad51-independent events in Saccharomyces cerevisiae by creating a DSB with the site-specific HO endonuclease and repairing the DSB with 80-nt single-stranded oligonucleotides (ssODNs), and confirmed these results by Cas9-mediated DSBs in combination with a bacterial retron system that produces ssDNA templates in vivo. We show that single strand template repair (SSTR), is dependent on Rad52, Rad59, Srs2 and the Mre11-Rad50-Xrs2 (MRX) complex, but unlike other Rad51-independent recombination events, independent of Rdh54. We show that Rad59 acts to alleviate the inhibition of Rad51 on Rad52's strand annealing activity both in SSTR and in single strand annealing (SSA). Gene editing is Rad51-dependent when double-stranded oligonucleotides of the same size and sequence are introduced as templates. The assimilation of mismatches during gene editing is dependent on the activity of Msh2, which acts very differently on the 3' side of the ssODN which can anneal directly to the resected DSB end compared to the 5' end. In addition DNA polymerase Polδ's 3' to 5' proofreading activity frequently excises a mismatch very close to the 3' end of the template. We further report that SSTR is accompanied by as much as a 600-fold increase in mutations in regions adjacent to the sequences directly undergoing repair. These DNA polymerase ζ-dependent mutations may compromise the accuracy of gene editing.
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Affiliation(s)
- Danielle N. Gallagher
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA, United States of America
| | - Nhung Pham
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
| | - Annie M. Tsai
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA, United States of America
| | - Nicolas V. Janto
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA, United States of America
| | - Jihyun Choi
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA, United States of America
| | - Grzegorz Ira
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
| | - James E. Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA, United States of America
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Wilkinson OJ, Carrasco C, Aicart-Ramos C, Moreno-Herrero F, Dillingham MS. Bulk and single-molecule analysis of a bacterial DNA2-like helicase-nuclease reveals a single-stranded DNA looping motor. Nucleic Acids Res 2020; 48:7991-8005. [PMID: 32621607 PMCID: PMC7430649 DOI: 10.1093/nar/gkaa562] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 06/12/2020] [Accepted: 06/19/2020] [Indexed: 11/14/2022] Open
Abstract
DNA2 is an essential enzyme involved in DNA replication and repair in eukaryotes. In a search for homologues of this protein, we identified and characterised Geobacillus stearothermophilus Bad, a bacterial DNA helicase-nuclease with similarity to human DNA2. We show that Bad contains an Fe-S cluster and identify four cysteine residues that are likely to co-ordinate the cluster by analogy to DNA2. The purified enzyme specifically recognises ss-dsDNA junctions and possesses ssDNA-dependent ATPase, ssDNA binding, ssDNA endonuclease, 5' to 3' ssDNA translocase and 5' to 3' helicase activity. Single molecule analysis reveals that Bad is a processive DNA motor capable of moving along DNA for distances of >4 kb at a rate of ∼200 bp per second at room temperature. Interestingly, as reported for the homologous human and yeast DNA2 proteins, the DNA unwinding activity of Bad is cryptic and can be unmasked by inactivating the intrinsic nuclease activity. Strikingly, our experiments show that the enzyme loops DNA while translocating, which is an emerging feature of processive DNA unwinding enzymes. The bacterial Bad enzymes will provide an excellent model system for understanding the biochemical properties of DNA2-like helicase-nucleases and DNA looping motor proteins in general.
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Affiliation(s)
- Oliver J Wilkinson
- School of Biochemistry, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Carolina Carrasco
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Cantoblanco, Madrid, Spain
| | - Clara Aicart-Ramos
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Cantoblanco, Madrid, Spain
| | - Fernando Moreno-Herrero
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Cantoblanco, Madrid, Spain
| | - Mark S Dillingham
- School of Biochemistry, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
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