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Vontalge EJ, Kavlashvili T, Dahmen SN, Cranford MT, Dewar JM. Control of DNA replication in vitro using a reversible replication barrier. Nat Protoc 2024; 19:1940-1983. [PMID: 38594502 PMCID: PMC11230854 DOI: 10.1038/s41596-024-00977-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 01/19/2024] [Indexed: 04/11/2024]
Abstract
A major obstacle to studying DNA replication is that it involves asynchronous and highly delocalized events. A reversible replication barrier overcomes this limitation and allows replication fork movement to be synchronized and localized, facilitating the study of replication fork function and replication coupled repair. Here we provide details on establishing a reversible replication barrier in vitro and using it to monitor different aspects of DNA replication. DNA template containing an array of lac operator (lacO) sequences is first bound to purified lac repressor (LacR). This substrate is then replicated in vitro using a biochemical replication system, which results in replication forks stalled on either side of the LacR array regardless of when or where they arise. Once replication forks are synchronized at the barrier, isopropyl-β-D-thiogalactopyranoside can be added to disrupt LacR binding so that replication forks synchronously resume synthesis. We describe how this approach can be employed to control replication fork elongation, termination, stalling and uncoupling, as well as assays that can be used to monitor these processes. We also explain how this approach can be adapted to control whether replication forks encounter a DNA lesion on the leading or lagging strand template and whether a converging fork is present. The required reagents can be prepared in 1-2 weeks and experiments using this approach are typically performed over 1-3 d. The main requirements for utilizing the LacR replication barrier are basic biochemical expertise and access to an in vitro system to study DNA replication. Investigators should also be trained in working with radioactive materials.
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Affiliation(s)
- Emma J Vontalge
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Tamar Kavlashvili
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Steven N Dahmen
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Matthew T Cranford
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - James M Dewar
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA.
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2
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Zagnoli-Vieira G, Brazina J, Van Den Bogaert K, Huybrechts W, Molenaers G, Caldecott KW, Van Esch H. Inactivating TDP2 missense mutation in siblings with congenital abnormalities reminiscent of fanconi anemia. Hum Genet 2023; 142:1417-1427. [PMID: 37558815 PMCID: PMC10449949 DOI: 10.1007/s00439-023-02589-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 07/15/2023] [Indexed: 08/11/2023]
Abstract
Mutations in TDP2, encoding tyrosyl-DNA phosphodiesterase 2, have been associated with a syndromal form of autosomal recessive spinocerebellar ataxia, type 23 (SCAR23). This is a very rare and progressive neurodegenerative disorder described in only nine patients to date, and caused by splice site or nonsense mutations that result in greatly reduced or absent TDP2 protein. TDP2 is required for the rapid repair of DNA double-strand breaks induced by abortive DNA topoisomerase II (TOP2) activity, important for genetic stability in post-mitotic cells such as neurons. Here, we describe a sibship that is homozygous for the first TDP2 missense mutation (p.Glu152Lys) and which presents with clinical features overlapping both SCAR23 and Fanconi anemia (FA). We show that in contrast to previously reported SCAR23 patients, fibroblasts derived from the current patient retain significant levels of TDP2 protein. However, this protein is catalytically inactive, resulting in reduced rates of repair of TOP2-induced DNA double-strand breaks and cellular hypersensitivity to the TOP2 poison, etoposide. The TDP2-mutated patient-derived fibroblasts do not display increased chromosome breakage following treatment with DNA crosslinking agents, but both TDP2-mutated and FA cells exhibit increased chromosome breakage in response to etoposide. This suggests that the FA pathway is required in response to TOP2-induced DNA lesions, providing a possible explanation for the clinical overlap between FA and the current TDP2-mutated patients. When reviewing the relatively small number of patients with SCAR23 that have been reported, it is clear that the phenotype of such patients can extend beyond neurological features, indicating that the TDP2 protein influences not only neural homeostasis but also other tissues as well.
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Affiliation(s)
- Guido Zagnoli-Vieira
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9RQ, UK.
- Wellcome Trust Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge, CB2 1QN, UK.
| | - Jan Brazina
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9RQ, UK
| | - Kris Van Den Bogaert
- Center for Human Genetics, University Hospitals Leuven, Herestraat 49, 3000, Louvain, Belgium
| | - Wim Huybrechts
- Center for Human Genetics, University Hospitals Leuven, Herestraat 49, 3000, Louvain, Belgium
| | - Guy Molenaers
- Pediatric Orthopedics, Department of Orthopedics, University Hospitals Leuven, Herestraat 49, 3000, Louvain, Belgium
| | - Keith W Caldecott
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9RQ, UK.
| | - Hilde Van Esch
- Center for Human Genetics, University Hospitals Leuven, Herestraat 49, 3000, Louvain, Belgium.
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3
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Ahmed-Seghir S, Jalan M, Grimsley HE, Sharma A, Twayana S, Kosiyatrakul ST, Thompson C, Schildkraut CL, Powell SN. A local ATR-dependent checkpoint pathway is activated by a site-specific replication fork block in human cells. eLife 2023; 12:RP87357. [PMID: 37647215 PMCID: PMC10468204 DOI: 10.7554/elife.87357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023] Open
Abstract
When replication forks encounter DNA lesions that cause polymerase stalling, a checkpoint pathway is activated. The ATR-dependent intra-S checkpoint pathway mediates detection and processing of sites of replication fork stalling to maintain genomic integrity. Several factors involved in the global checkpoint pathway have been identified, but the response to a single replication fork barrier (RFB) is poorly understood. We utilized the Escherichia coli-based Tus-Ter system in human MCF7 cells and showed that the Tus protein binding to TerB sequences creates an efficient site-specific RFB. The single fork RFB was sufficient to activate a local, but not global, ATR-dependent checkpoint response that leads to phosphorylation and accumulation of DNA damage sensor protein γH2AX, confined locally to within a kilobase of the site of stalling. These data support a model of local management of fork stalling, which allows global replication at sites other than the RFB to continue to progress without delay.
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Affiliation(s)
- Sana Ahmed-Seghir
- Department of Radiation Oncology and the Molecular Biology Program, Memorial Sloan Kettering Cancer CenterNew YorkUnited States
| | - Manisha Jalan
- Department of Radiation Oncology and the Molecular Biology Program, Memorial Sloan Kettering Cancer CenterNew YorkUnited States
| | - Helen E Grimsley
- Department of Radiation Oncology and the Molecular Biology Program, Memorial Sloan Kettering Cancer CenterNew YorkUnited States
| | - Aman Sharma
- Department of Radiation Oncology and the Molecular Biology Program, Memorial Sloan Kettering Cancer CenterNew YorkUnited States
| | - Shyam Twayana
- Department of Cell Biology, Albert Einstein College of MedicineNew YorkUnited States
| | | | - Christopher Thompson
- Department of Radiation Oncology and the Molecular Biology Program, Memorial Sloan Kettering Cancer CenterNew YorkUnited States
| | - Carl L Schildkraut
- Department of Cell Biology, Albert Einstein College of MedicineNew YorkUnited States
| | - Simon N Powell
- Department of Radiation Oncology and the Molecular Biology Program, Memorial Sloan Kettering Cancer CenterNew YorkUnited States
- Molecular Biology Program, Memorial Sloan Kettering Cancer CenterNew YorkUnited States
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4
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Alghoul E, Basbous J, Constantinou A. Compartmentalization of the DNA damage response: Mechanisms and functions. DNA Repair (Amst) 2023; 128:103524. [PMID: 37320957 DOI: 10.1016/j.dnarep.2023.103524] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 05/31/2023] [Accepted: 06/02/2023] [Indexed: 06/17/2023]
Abstract
Cells have evolved an arsenal of molecular mechanisms to respond to continuous alterations in the primary structure of DNA. At the cellular level, DNA damage response proteins accumulate at sites of DNA damage and organize into nuclear foci. As recounted by Errol Friedberg, pioneering work on DNA repair in the 1930 s was stimulated by collaborations between physicists and geneticists. In recent years, the introduction of ideas from physics on self-organizing compartments has taken the field of cell biology by storm. Percolation and phase separation theories are increasingly used to model the self-assembly of compartments, called biomolecular condensates, that selectively concentrate molecules without a surrounding membrane. In this review, we discuss these concepts in the context of the DNA damage response. We discuss how studies of DNA repair foci as condensates can link molecular mechanisms with cell physiological functions, provide new insights into regulatory mechanisms, and open new perspectives for targeting DNA damage responses for therapeutic purposes.
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Affiliation(s)
- Emile Alghoul
- Institut de Génétique Humaine, Université de Montpellier, CNRS, Montpellier, France
| | - Jihane Basbous
- Institut de Génétique Humaine, Université de Montpellier, CNRS, Montpellier, France
| | - Angelos Constantinou
- Institut de Génétique Humaine, Université de Montpellier, CNRS, Montpellier, France.
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Ahmed-Seghir S, Jalan M, Grimsley HE, Sharma A, Twayana S, Kosiyatrakul ST, Thompson C, Schildkraut CL, Powell SN. A local ATR-dependent checkpoint pathway is activated by a site-specific replication fork block in human cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.26.534293. [PMID: 36993263 PMCID: PMC10055377 DOI: 10.1101/2023.03.26.534293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
Abstract
When replication forks encounter DNA lesions that cause polymerase stalling a checkpoint pathway is activated. The ATR-dependent intra-S checkpoint pathway mediates detection and processing of sites of replication fork stalling to maintain genomic integrity. Several factors involved in the global checkpoint pathway have been identified, but the response to a single replication fork barrier (RFB) is poorly understood. We utilized the E.coli -based Tus- Ter system in human MCF7 cells and showed that the Tus protein binding to TerB sequences creates an efficient site-specific RFB. The single fork RFB was sufficient to activate a local, but not global, ATR-dependent checkpoint response that leads to phosphorylation and accumulation of DNA damage sensor protein γH2AX, confined locally to within a kilobase of the site of stalling. These data support a model of local management of fork stalling, which allows global replication at sites other than the RFB to continue to progress without delay.
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6
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Alghoul E, Paloni M, Takedachi A, Urbach S, Barducci A, Gaillard PH, Basbous J, Constantinou A. Compartmentalization of the SUMO/RNF4 pathway by SLX4 drives DNA repair. Mol Cell 2023; 83:1640-1658.e9. [PMID: 37059091 DOI: 10.1016/j.molcel.2023.03.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 02/06/2023] [Accepted: 03/21/2023] [Indexed: 04/16/2023]
Abstract
SLX4, disabled in the Fanconi anemia group P, is a scaffolding protein that coordinates the action of structure-specific endonucleases and other proteins involved in the replication-coupled repair of DNA interstrand cross-links. Here, we show that SLX4 dimerization and SUMO-SIM interactions drive the assembly of SLX4 membraneless compartments in the nucleus called condensates. Super-resolution microscopy reveals that SLX4 forms chromatin-bound clusters of nanocondensates. We report that SLX4 compartmentalizes the SUMO-RNF4 signaling pathway. SENP6 and RNF4 regulate the assembly and disassembly of SLX4 condensates, respectively. SLX4 condensation per se triggers the selective modification of proteins by SUMO and ubiquitin. Specifically, SLX4 condensation induces ubiquitylation and chromatin extraction of topoisomerase 1 DNA-protein cross-links. SLX4 condensation also induces the nucleolytic degradation of newly replicated DNA. We propose that the compartmentalization of proteins by SLX4 through site-specific interactions ensures the spatiotemporal control of protein modifications and nucleolytic reactions during DNA repair.
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Affiliation(s)
- Emile Alghoul
- Institut de Génétique Humaine, Université de Montpellier, CNRS, Montpellier, France
| | - Matteo Paloni
- Centre de Biologie Structurale (CBS), Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Arato Takedachi
- Aix Marseille Univ, CNRS, INSERM, Institut Paoli-Calmettes, CRCM, Marseille, France
| | - Serge Urbach
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France; Montpellier RIO Imaging, Montpellier, France
| | - Alessandro Barducci
- Centre de Biologie Structurale (CBS), Université de Montpellier, CNRS, INSERM, Montpellier, France
| | | | - Jihane Basbous
- Institut de Génétique Humaine, Université de Montpellier, CNRS, Montpellier, France.
| | - Angelos Constantinou
- Institut de Génétique Humaine, Université de Montpellier, CNRS, Montpellier, France.
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7
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PARP Inhibitors and Proteins Interacting with SLX4. Cancers (Basel) 2023; 15:cancers15030997. [PMID: 36765954 PMCID: PMC9913592 DOI: 10.3390/cancers15030997] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 01/31/2023] [Accepted: 01/31/2023] [Indexed: 02/08/2023] Open
Abstract
PARP inhibitors are small molecules currently used with success in the treatment of certain cancer patients. Their action was first shown to be specific to cells with DNA repair deficiencies, such as BRCA-mutant cancers. However, recent work has suggested clinical interest of these drugs beyond this group of patients. Preclinical data on relationships between the activity of PARP inhibitors and other proteins involved in DNA repair exist, and this review will only highlight findings on the SLX4 protein and its interacting protein partners. As suggested from these available data and depending on further validations, new treatment strategies could be developed in order to broaden the use for PARP inhibitors in cancer patients.
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