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Bhowmick R, Hickson ID, Liu Y. Completing genome replication outside of S phase. Mol Cell 2023; 83:3596-3607. [PMID: 37716351 DOI: 10.1016/j.molcel.2023.08.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/03/2023] [Accepted: 08/17/2023] [Indexed: 09/18/2023]
Abstract
Mitotic DNA synthesis (MiDAS) is an unusual form of DNA replication that occurs during mitosis. Initially, MiDAS was characterized as a process associated with intrinsically unstable loci known as common fragile sites that occurs after cells experience DNA replication stress (RS). However, it is now believed to be a more widespread "salvage" mechanism that is called upon to complete the duplication of any under-replicated genomic region. Emerging data suggest that MiDAS is a DNA repair process potentially involving two or more pathways working in parallel or sequentially. In this review, we introduce the causes of RS, regions of the human genome known to be especially vulnerable to RS, and the strategies used to complete DNA replication outside of S phase. Additionally, because MiDAS is a prominent feature of aneuploid cancer cells, we will discuss how targeting MiDAS might potentially lead to improvements in cancer therapy.
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Affiliation(s)
- Rahul Bhowmick
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3B, 2200 Copenhagen N, Denmark; Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Ian D Hickson
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3B, 2200 Copenhagen N, Denmark.
| | - Ying Liu
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3B, 2200 Copenhagen N, Denmark.
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2
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Marini V, Nikulenkov F, Samadder P, Juul S, Knudsen BR, Krejci L. MUS81 cleaves TOP1-derived lesions and other DNA-protein cross-links. BMC Biol 2023; 21:110. [PMID: 37194054 DOI: 10.1186/s12915-023-01614-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 05/04/2023] [Indexed: 05/18/2023] Open
Abstract
BACKGROUND DNA-protein cross-links (DPCs) are one of the most deleterious DNA lesions, originating from various sources, including enzymatic activity. For instance, topoisomerases, which play a fundamental role in DNA metabolic processes such as replication and transcription, can be trapped and remain covalently bound to DNA in the presence of poisons or nearby DNA damage. Given the complexity of individual DPCs, numerous repair pathways have been described. The protein tyrosyl-DNA phosphodiesterase 1 (Tdp1) has been demonstrated to be responsible for removing topoisomerase 1 (Top1). Nevertheless, studies in budding yeast have indicated that alternative pathways involving Mus81, a structure-specific DNA endonuclease, could also remove Top1 and other DPCs. RESULTS This study shows that MUS81 can efficiently cleave various DNA substrates modified by fluorescein, streptavidin or proteolytically processed topoisomerase. Furthermore, the inability of MUS81 to cleave substrates bearing native TOP1 suggests that TOP1 must be either dislodged or partially degraded prior to MUS81 cleavage. We demonstrated that MUS81 could cleave a model DPC in nuclear extracts and that depletion of TDP1 in MUS81-KO cells induces sensitivity to the TOP1 poison camptothecin (CPT) and affects cell proliferation. This sensitivity is only partially suppressed by TOP1 depletion, indicating that other DPCs might require the MUS81 activity for cell proliferation. CONCLUSIONS Our data indicate that MUS81 and TDP1 play independent roles in the repair of CPT-induced lesions, thus representing new therapeutic targets for cancer cell sensitisation in combination with TOP1 inhibitors.
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Affiliation(s)
- Victoria Marini
- Department of Biology, Masaryk University, Kamenice 5/B07, Brno, 62500, Czech Republic
- International Clinical Research Center, Center for Biomolecular and Cellular Engineering, St. Anne's University Hospital Brno, Pekařská 53, Brno, 60200, Czech Republic
| | - Fedor Nikulenkov
- Department of Biology, Masaryk University, Kamenice 5/B07, Brno, 62500, Czech Republic
| | - Pounami Samadder
- Department of Biology, Masaryk University, Kamenice 5/B07, Brno, 62500, Czech Republic
| | - Sissel Juul
- Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, Aarhus, 8000, Denmark
| | - Birgitta R Knudsen
- Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, Aarhus, 8000, Denmark
| | - Lumir Krejci
- Department of Biology, Masaryk University, Kamenice 5/B07, Brno, 62500, Czech Republic.
- International Clinical Research Center, Center for Biomolecular and Cellular Engineering, St. Anne's University Hospital Brno, Pekařská 53, Brno, 60200, Czech Republic.
- National Centre for Biomolecular Research, Masaryk University, Kamenice 5/C04, Brno, 625 00, Czech Republic.
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3
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Payliss BJ, Tse YWE, Reichheld SE, Lemak A, Yun HY, Houliston S, Patel A, Arrowsmith CH, Sharpe S, Wyatt HD. Phosphorylation of the DNA repair scaffold SLX4 drives folding of the SAP domain and activation of the MUS81-EME1 endonuclease. Cell Rep 2022; 41:111537. [DOI: 10.1016/j.celrep.2022.111537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 08/11/2022] [Accepted: 09/29/2022] [Indexed: 11/03/2022] Open
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4
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Firnau MB, Brieger A. CK2 and the Hallmarks of Cancer. Biomedicines 2022; 10:biomedicines10081987. [PMID: 36009534 PMCID: PMC9405757 DOI: 10.3390/biomedicines10081987] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 08/08/2022] [Accepted: 08/10/2022] [Indexed: 11/29/2022] Open
Abstract
Cancer is a leading cause of death worldwide. Casein kinase 2 (CK2) is commonly dysregulated in cancer, impacting diverse molecular pathways. CK2 is a highly conserved serine/threonine kinase, constitutively active and ubiquitously expressed in eukaryotes. With over 500 known substrates and being estimated to be responsible for up to 10% of the human phosphoproteome, it is of significant importance. A broad spectrum of diverse types of cancer cells has been already shown to rely on disturbed CK2 levels for their survival. The hallmarks of cancer provide a rationale for understanding cancer’s common traits. They constitute the maintenance of proliferative signaling, evasion of growth suppressors, resisting cell death, enabling of replicative immortality, induction of angiogenesis, the activation of invasion and metastasis, as well as avoidance of immune destruction and dysregulation of cellular energetics. In this work, we have compiled evidence from the literature suggesting that CK2 modulates all hallmarks of cancer, thereby promoting oncogenesis and operating as a cancer driver by creating a cellular environment favorable to neoplasia.
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5
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Hua Z, Fang Q, Zhang D, Luo Z, Yuan C, Lin Z. Crystal structure of the human MUS81-EME2 complex. Structure 2022; 30:743-752.e3. [DOI: 10.1016/j.str.2022.02.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 01/27/2022] [Accepted: 02/16/2022] [Indexed: 10/18/2022]
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6
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Payliss BJ, Patel A, Sheppard AC, Wyatt HDM. Exploring the Structures and Functions of Macromolecular SLX4-Nuclease Complexes in Genome Stability. Front Genet 2021; 12:784167. [PMID: 34804132 PMCID: PMC8599992 DOI: 10.3389/fgene.2021.784167] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 10/21/2021] [Indexed: 12/15/2022] Open
Abstract
All organisms depend on the ability of cells to accurately duplicate and segregate DNA into progeny. However, DNA is frequently damaged by factors in the environment and from within cells. One of the most dangerous lesions is a DNA double-strand break. Unrepaired breaks are a major driving force for genome instability. Cells contain sophisticated DNA repair networks to counteract the harmful effects of genotoxic agents, thus safeguarding genome integrity. Homologous recombination is a high-fidelity, template-dependent DNA repair pathway essential for the accurate repair of DNA nicks, gaps and double-strand breaks. Accurate homologous recombination depends on the ability of cells to remove branched DNA structures that form during repair, which is achieved through the opposing actions of helicases and structure-selective endonucleases. This review focuses on a structure-selective endonuclease called SLX1-SLX4 and the macromolecular endonuclease complexes that assemble on the SLX4 scaffold. First, we discuss recent developments that illuminate the structure and biochemical properties of this somewhat atypical structure-selective endonuclease. We then summarize the multifaceted roles that are fulfilled by human SLX1-SLX4 and its associated endonucleases in homologous recombination and genome stability. Finally, we discuss recent work on SLX4-binding proteins that may represent integral components of these macromolecular nuclease complexes, emphasizing the structure and function of a protein called SLX4IP.
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Affiliation(s)
- Brandon J Payliss
- Department of Biochemistry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Ayushi Patel
- Department of Biochemistry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Anneka C Sheppard
- Department of Biochemistry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Haley D M Wyatt
- Department of Biochemistry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada.,Canada Research Chairs Program, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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7
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St Germain C, Zhao H, Barlow JH. Transcription-Replication Collisions-A Series of Unfortunate Events. Biomolecules 2021; 11:1249. [PMID: 34439915 PMCID: PMC8391903 DOI: 10.3390/biom11081249] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/12/2021] [Accepted: 08/17/2021] [Indexed: 02/07/2023] Open
Abstract
Transcription-replication interactions occur when DNA replication encounters genomic regions undergoing transcription. Both replication and transcription are essential for life and use the same DNA template making conflicts unavoidable. R-loops, DNA supercoiling, DNA secondary structure, and chromatin-binding proteins are all potential obstacles for processive replication or transcription and pose an even more potent threat to genome integrity when these processes co-occur. It is critical to maintaining high fidelity and processivity of transcription and replication while navigating through a complex chromatin environment, highlighting the importance of defining cellular pathways regulating transcription-replication interaction formation, evasion, and resolution. Here we discuss how transcription influences replication fork stability, and the safeguards that have evolved to navigate transcription-replication interactions and maintain genome integrity in mammalian cells.
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Affiliation(s)
- Commodore St Germain
- School of Mathematics and Science, Solano Community College, 4000 Suisun Valley Road, Fairfield, CA 94534, USA
- Department of Microbiology and Molecular Genetics, University of California Davis, One Shields Avenue, Davis, CA 95616, USA;
| | - Hongchang Zhao
- Department of Microbiology and Molecular Genetics, University of California Davis, One Shields Avenue, Davis, CA 95616, USA;
| | - Jacqueline H. Barlow
- Department of Microbiology and Molecular Genetics, University of California Davis, One Shields Avenue, Davis, CA 95616, USA;
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8
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Simoneau A, Zou L. An extending ATR-CHK1 circuitry: the replication stress response and beyond. Curr Opin Genet Dev 2021; 71:92-98. [PMID: 34329853 DOI: 10.1016/j.gde.2021.07.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 07/02/2021] [Accepted: 07/08/2021] [Indexed: 02/06/2023]
Abstract
The maintenance of genomic integrity relies on the coordination of a wide range of cellular processes and efficient repair of DNA damage. Since its discovery over two decades ago, the ATR kinase has been recognized as the master regulator of the circuitry orchestrating the cellular responses to DNA damage and replication stress. Recent studies reveal that ATR additionally functions in the unperturbed cell cycle through its control of replication fork speed and stability, replication origin firing, completion of genome duplication, and chromosome segregation. Here, we discuss several recently discovered mechanisms through which ATR safeguards genomic integrity during the cell cycle, from S phase to mitosis.
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Affiliation(s)
- Antoine Simoneau
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA
| | - Lee Zou
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA; Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
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9
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Abstract
Unlike bacteria, mammalian cells need to complete DNA replication before segregating their chromosomes for the maintenance of genome integrity. Thus, cells have evolved efficient pathways to restore stalled and/or collapsed replication forks during S-phase, and when necessary, also to delay cell cycle progression to ensure replication completion. However, strong evidence shows that cells can proceed to mitosis with incompletely replicated DNA when under mild replication stress (RS) conditions. Consequently, the incompletely replicated genomic gaps form, predominantly at common fragile site regions, where the converging fork-like DNA structures accumulate. These branched structures pose a severe threat to the faithful disjunction of chromosomes as they physically interlink the partially duplicated sister chromatids. In this review, we provide an overview discussing how cells respond and deal with the under-replicated DNA structures that escape from the S/G2 surveillance system. We also focus on recent research of a mitotic break-induced replication pathway (also known as mitotic DNA repair synthesis), which has been proposed to operate during prophase in an attempt to finish DNA synthesis at the under-replicated genomic regions. Finally, we discuss recent data on how mild RS may cause chromosome instability and mutations that accelerate cancer genome evolution.
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Affiliation(s)
- Camelia Mocanu
- Chromosome Dynamics and Stability Group, Genome Damage and Stability Centre, University of Sussex, Brighton BN1 7BG, UK
| | - Kok-Lung Chan
- Chromosome Dynamics and Stability Group, Genome Damage and Stability Centre, University of Sussex, Brighton BN1 7BG, UK
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10
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Panichnantakul P, Patel A, Tse EYW, Wyatt HDM. An open-source platform to quantify subnuclear foci and protein colocalization in response to replication stress. DNA Repair (Amst) 2021; 105:103156. [PMID: 34139663 DOI: 10.1016/j.dnarep.2021.103156] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 06/04/2021] [Accepted: 06/05/2021] [Indexed: 11/28/2022]
Abstract
Nuclear reorganization, including the localization of proteins into discrete subnuclear foci, is a hallmark of the cellular response to DNA damage and replication stress. These foci are thought to represent transient environments or repair factories, in which the lesion is sequestered with molecules and co-factors that catalyze repair. For example, nuclear foci contain signaling proteins that recruit transducer proteins. One important class of transducers is the structure-selective endonucleases, such as SLX1-SLX4, MUS81-EME1, and XPF-ERCC1, which remove branched DNA structures that form during repair. The relocalization of structure-selective endonucleases into subnuclear foci provides a visual read-out for the presence of direct DNA damage, replication barriers, or DNA entanglements and can be monitored using fluorescence microscopy. By simultaneously probing for two or more fluorescent signals, fluorescence microscopy can also provide insights into the proximal association of proteins within a local environment. Here, we report an open-source and semi-automated method to detect and quantify subnuclear foci, as well as foci colocalization and the accompanying pixel-based colocalization metrics. We use this pipeline to show that pre-mitotic nuclei contain a basal threshold of foci marked by SLX1-SLX4, MUS81, or XPF. Some of these foci colocalize with FANCD2 and have a high degree of correlation and co-occurrence. We also show that pre-mitotic cells experiencing replication stress contain elevated levels of foci containing SLX1-SLX4 or XPF, but not MUS81. These results point towards a role for SLX1-SLX4 and XPF-ERCC1 in the early cellular response to replication stress. Nevertheless, most of the foci that form in response to replication stress contain either FANCD2 or one of the three endonucleases. Altogether, our work highlights the compositional heterogeneity of subnuclear foci that form in response to replication stress. We also describe a user-friendly pipeline that can be used to characterize these dynamic structures.
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Affiliation(s)
- Pudchalaluck Panichnantakul
- Department of Biochemistry, University of Toronto, MaRS Centre, 661 University Ave., Toronto, ON, M5G 1M1, Canada
| | - Ayushi Patel
- Department of Biochemistry, University of Toronto, MaRS Centre, 661 University Ave., Toronto, ON, M5G 1M1, Canada
| | - Elizabeth Y W Tse
- Department of Biochemistry, University of Toronto, MaRS Centre, 661 University Ave., Toronto, ON, M5G 1M1, Canada
| | - Haley D M Wyatt
- Department of Biochemistry, University of Toronto, MaRS Centre, 661 University Ave., Toronto, ON, M5G 1M1, Canada; Canada Research Chairs Program, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada.
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11
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Small molecule induces mitochondrial fusion for neuroprotection via targeting CK2 without affecting its conventional kinase activity. Signal Transduct Target Ther 2021; 6:71. [PMID: 33602894 PMCID: PMC7893052 DOI: 10.1038/s41392-020-00447-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 11/23/2020] [Accepted: 11/24/2020] [Indexed: 01/31/2023] Open
Abstract
Mitochondrial fusion/fission dynamics plays a fundamental role in neuroprotection; however, there is still a severe lack of therapeutic targets for this biological process. Here, we found that the naturally derived small molecule echinacoside (ECH) significantly promotes mitochondrial fusion progression. ECH selectively binds to the previously uncharacterized casein kinase 2 (CK2) α' subunit (CK2α') as a direct cellular target, and genetic knockdown of CK2α' abolishes ECH-mediated mitochondrial fusion. Mechanistically, ECH allosterically regulates CK2α' conformation to recruit basic transcription factor 3 (BTF3) to form a binary protein complex. Then, the CK2α'/BTF3 complex facilitates β-catenin nuclear translocation to activate TCF/LEF transcription factors and stimulate transcription of the mitochondrial fusion gene Mfn2. Strikingly, in a mouse middle cerebral artery occlusion (MCAO) model, ECH administration was found to significantly improve cerebral injuries and behavioral deficits by enhancing Mfn2 expression in wild-type but not CK2α'+/- mice. Taken together, our findings reveal, for the first time, that CK2 is essential for promoting mitochondrial fusion in a Wnt/β-catenin-dependent manner and suggest that pharmacologically targeting CK2 is a promising therapeutic strategy for ischemic stroke.
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12
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Bagge J, Oestergaard VH, Lisby M. Functions of TopBP1 in preserving genome integrity during mitosis. Semin Cell Dev Biol 2020; 113:57-64. [PMID: 32912640 DOI: 10.1016/j.semcdb.2020.08.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 07/06/2020] [Accepted: 08/26/2020] [Indexed: 12/20/2022]
Abstract
TopBP1/Rad4/Dpb11 is an essential eukaryotic protein with important roles in DNA replication, DNA repair, DNA damage checkpoint activation, and chromosome segregation. TopBP1 serves as a scaffold to assemble protein complexes in a phosphorylation-dependent manner via its multiple BRCT-repeats. Recently, it has become clear that TopBP1 is repurposed to scaffold different processes dependent on cell cycle regulated changes in phosphorylation of client proteins. Here we review the functions of human TopBP1 in maintaining genome integrity during mitosis.
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Affiliation(s)
- Jonas Bagge
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Vibe H Oestergaard
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Michael Lisby
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark.
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13
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CRL4Cdt2 ubiquitin ligase regulates Dna2 and Rad16 (XPF) nucleases by targeting Pxd1 for degradation. PLoS Genet 2020; 16:e1008933. [PMID: 32692737 PMCID: PMC7394458 DOI: 10.1371/journal.pgen.1008933] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 07/31/2020] [Accepted: 06/15/2020] [Indexed: 01/19/2023] Open
Abstract
Structure-specific endonucleases (SSEs) play key roles in DNA replication, recombination, and repair. SSEs must be tightly regulated to ensure genome stability but their regulatory mechanisms remain incompletely understood. Here, we show that in the fission yeast Schizosaccharomyces pombe, the activities of two SSEs, Dna2 and Rad16 (ortholog of human XPF), are temporally controlled during the cell cycle by the CRL4Cdt2 ubiquitin ligase. CRL4Cdt2 targets Pxd1, an inhibitor of Dna2 and an activator of Rad16, for degradation in S phase. The ubiquitination and degradation of Pxd1 is dependent on CRL4Cdt2, PCNA, and a PCNA-binding degron motif on Pxd1. CRL4Cdt2-mediated Pxd1 degradation prevents Pxd1 from interfering with the normal S-phase functions of Dna2. Moreover, Pxd1 degradation leads to a reduction of Rad16 nuclease activity in S phase, and restrains Rad16-mediated single-strand annealing, a hazardous pathway of repairing double-strand breaks. These results demonstrate a new role of the CRL4Cdt2 ubiquitin ligase in genome stability maintenance and shed new light on how SSE activities are regulated during the cell cycle. Structure-specific endonucleases are enzymes that process DNA intermediates generated in DNA replication, recombination, and repair. Proper regulation of these enzymes is critical for maintaining genome stability. Dna2 and XPF are two such enzymes present across eukaryotes, from yeasts to humans. Here, we show that in the fission yeast Schizosaccharomyces pombe, the activities of Dna2 and Rad16 (the equivalent of human XPF) are temporally controlled during the cell cycle by the CRL4Cdt2 ubiquitin E3 ligase. In the S phase of the cell cycle, CRL4Cdt2 promotes the degradation of Pxd1, which is an inhibitor of Dna2 and an activator of Rad16. Through targeting Pxd1 for degradation, CRL4Cdt2 increases the activity of Dna2 in S phase and is important for the normal S-phase function of Dna2. Meanwhile, the degradation of Pxd1 reduces the activity of Rad16 in S phase, and curtails Rad16-dependent single-strand annealing, a mutagenic DNA repair pathway. Our findings uncover a new mechanism regulating two important endonucleases during the cell cycle, and reveal a new way of coordinating endonucleases to safeguard genome stability.
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14
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Aiello FA, Palma A, Malacaria E, Zheng L, Campbell JL, Shen B, Franchitto A, Pichierri P. RAD51 and mitotic function of mus81 are essential for recovery from low-dose of camptothecin in the absence of the WRN exonuclease. Nucleic Acids Res 2020; 47:6796-6810. [PMID: 31114910 PMCID: PMC6648349 DOI: 10.1093/nar/gkz431] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 05/02/2019] [Accepted: 05/07/2019] [Indexed: 11/13/2022] Open
Abstract
Stabilization of stalled replication forks prevents excessive fork reversal or degradation, which can undermine genome integrity. The WRN protein is unique among the other human RecQ family members to possess exonuclease activity. However, the biological role of the WRN exonuclease is poorly defined. Recently, the WRN exonuclease has been linked to protection of stalled forks from degradation. Alternative processing of perturbed forks has been associated to chemoresistance of BRCA-deficient cancer cells. Thus, we used WRN exonuclease-deficiency as a model to investigate the fate of perturbed forks undergoing degradation, but in a BRCA wild-type condition. We find that, upon treatment with clinically-relevant nanomolar doses of the Topoisomerase I inhibitor camptothecin, loss of WRN exonuclease stimulates fork inactivation and accumulation of parental gaps, which engages RAD51. Such mechanism affects reinforcement of CHK1 phosphorylation and causes persistence of RAD51 during recovery from treatment. Notably, in WRN exonuclease-deficient cells, persistence of RAD51 correlates with elevated mitotic phosphorylation of MUS81 at Ser87, which is essential to prevent excessive mitotic abnormalities. Altogether, these findings indicate that aberrant fork degradation, in the presence of a wild-type RAD51 axis, stimulates RAD51-mediated post-replicative repair and engagement of the MUS81 complex to limit genome instability and cell death.
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Affiliation(s)
- Francesca Antonella Aiello
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Roma, Italy
| | - Anita Palma
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Roma, Italy
| | - Eva Malacaria
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Roma, Italy
| | - Li Zheng
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010-3000, USA
| | - Judith L Campbell
- Braun Laboratories, California Institute of Technology, Pasadena, CA 91125, USA
| | - Binghui Shen
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010-3000, USA
| | - Annapaola Franchitto
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Roma, Italy
| | - Pietro Pichierri
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Roma, Italy.,Istituto Nazionale Biostrutture e Biosistemi, Roma, Italy
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15
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Lu R, Xie S, Wang Y, Zheng H, Zhang H, Deng M, Shi W, Zhong A, Chen M, Zhang M, Xu X, Shammas MA, Guo L. MUS81 Participates in the Progression of Serous Ovarian Cancer Associated With Dysfunctional DNA Repair System. Front Oncol 2019; 9:1189. [PMID: 31803609 PMCID: PMC6873896 DOI: 10.3389/fonc.2019.01189] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 10/21/2019] [Indexed: 12/31/2022] Open
Abstract
Objective: Methyl methanesulfonate ultraviolet sensitive gene clone 81 (MUS81) is a structure-specific endonuclease that plays a pivotal role in the DNA repair system of cancer cells. In this study, we aim to elucidate the potential association between the dysfunction of MUS81 and the progression of Serous Ovarian Cancer (SOC). Methods: To investigate the association between MUS81 and prognosis of SOC, immunohistochemistry technology and qPCR were used to analyze the level of MUS81 expression, and transcriptional profile analysis and protein interaction screening chip were used to explore the MUS81 related signal pathways. Random amplified polymorphic DNA (RAPD) analysis, immunofluorescence and comet assays were further performed to evaluate genomic instability and DNA damage status of transduced SOC cells. Experiments both in vitro and in vivo were conducted to verify the impact of MUS81 silencing on chemotherapeutic drug sensitivity of SOC. Results: The overexpression of MUS81 in SOC tissues was related to poor clinical outcomes. The transcriptional chip data showed that MUS81 was involved in multiple pathways associated with DNA repair. Deficiency of MUS81 intensified the genome instability of SOC cells, promoted the emergence of DSBs and restrained the formation of RAD51 foci in SOC cells with exposure to UV. Furthermore, downregulation of MUS81 enhanced the sensitivity to Camptothecin and Olaparib in SOC cell lines and xenograft model. Conclusions: MUS81 is involved in the progression of SOC and inhibition of MUS81 could augment the susceptibility to chemotherapeutic agents. MUS81 might represent a novel molecular target for SOC chemotherapy.
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Affiliation(s)
- Renquan Lu
- Department of Clinical Laboratory, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Suhong Xie
- Department of Clinical Laboratory, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yanchun Wang
- Department of Clinical Laboratory, Fudan University Shanghai Cancer Center, Shanghai, China
| | - Hui Zheng
- Department of Clinical Laboratory, Fudan University Shanghai Cancer Center, Shanghai, China
| | - Hongqin Zhang
- Department of Clinical Laboratory, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Minjie Deng
- Department of Clinical Laboratory, Fudan University Shanghai Cancer Center, Shanghai, China
| | - Weizhong Shi
- Department of Clinical Laboratory, Shanghai Proton and Heavy Ion Center, Shanghai, China
| | - Ailing Zhong
- Department of Clinical Laboratory, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Miaomiao Chen
- Department of Clinical Laboratory, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Meiqin Zhang
- Department of Gynecological Oncology, Fudan University Shanghai Cancer Center, Shanghai, China
| | - Xiaofeng Xu
- Department of Clinical Laboratory, Fudan University Shanghai Cancer Center, Shanghai, China
| | - Masood A Shammas
- Department of Medical Oncology, Dana Farber (Harvard) Cancer Institute, Boston, MA, United States
| | - Lin Guo
- Department of Clinical Laboratory, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
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16
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Falquet B, Rass U. Structure-Specific Endonucleases and the Resolution of Chromosome Underreplication. Genes (Basel) 2019; 10:E232. [PMID: 30893921 PMCID: PMC6470701 DOI: 10.3390/genes10030232] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 03/11/2019] [Accepted: 03/13/2019] [Indexed: 12/11/2022] Open
Abstract
Complete genome duplication in every cell cycle is fundamental for genome stability and cell survival. However, chromosome replication is frequently challenged by obstacles that impede DNA replication fork (RF) progression, which subsequently causes replication stress (RS). Cells have evolved pathways of RF protection and restart that mitigate the consequences of RS and promote the completion of DNA synthesis prior to mitotic chromosome segregation. If there is entry into mitosis with underreplicated chromosomes, this results in sister-chromatid entanglements, chromosome breakage and rearrangements and aneuploidy in daughter cells. Here, we focus on the resolution of persistent replication intermediates by the structure-specific endonucleases (SSEs) MUS81, SLX1-SLX4 and GEN1. Their actions and a recently discovered pathway of mitotic DNA repair synthesis have emerged as important facilitators of replication completion and sister chromatid detachment in mitosis. As RS is induced by oncogene activation and is a common feature of cancer cells, any advances in our understanding of the molecular mechanisms related to chromosome underreplication have important biomedical implications.
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Affiliation(s)
- Benoît Falquet
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland.
- Faculty of Natural Sciences, University of Basel, Petersplatz 10, CH-4003 Basel, Switzerland.
| | - Ulrich Rass
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK.
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17
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Kim SM, Forsburg SL. Regulation of Structure-Specific Endonucleases in Replication Stress. Genes (Basel) 2018; 9:genes9120634. [PMID: 30558228 PMCID: PMC6316474 DOI: 10.3390/genes9120634] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/11/2018] [Accepted: 12/12/2018] [Indexed: 12/16/2022] Open
Abstract
Replication stress results in various forms of aberrant replication intermediates that need to be resolved for faithful chromosome segregation. Structure-specific endonucleases (SSEs) recognize DNA secondary structures rather than primary sequences and play key roles during DNA repair and replication stress. Holliday junction resolvase MUS81 (methyl methane sulfonate (MMS), and UV-sensitive protein 81) and XPF (xeroderma pigmentosum group F-complementing protein) are a subset of SSEs that resolve aberrant replication structures. To ensure genome stability and prevent unnecessary DNA breakage, these SSEs are tightly regulated by the cell cycle and replication checkpoints. We discuss the regulatory network that control activities of MUS81 and XPF and briefly mention other SSEs involved in the resolution of replication intermediates.
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Affiliation(s)
- Seong Min Kim
- Program in Molecular & Computational Biology, University of Southern California, Los Angeles, CA 90089, USA.
| | - Susan L Forsburg
- Program in Molecular & Computational Biology, University of Southern California, Los Angeles, CA 90089, USA.
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