1
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Reginato G, Dello Stritto MR, Wang Y, Hao J, Pavani R, Schmitz M, Halder S, Morin V, Cannavo E, Ceppi I, Braunshier S, Acharya A, Ropars V, Charbonnier JB, Jinek M, Nussenzweig A, Ha T, Cejka P. HLTF disrupts Cas9-DNA post-cleavage complexes to allow DNA break processing. Nat Commun 2024; 15:5789. [PMID: 38987539 PMCID: PMC11237066 DOI: 10.1038/s41467-024-50080-y] [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] [Received: 01/31/2024] [Accepted: 06/28/2024] [Indexed: 07/12/2024] Open
Abstract
The outcome of CRISPR-Cas-mediated genome modifications is dependent on DNA double-strand break (DSB) processing and repair pathway choice. Homology-directed repair (HDR) of protein-blocked DSBs requires DNA end resection that is initiated by the endonuclease activity of the MRE11 complex. Using reconstituted reactions, we show that Cas9 breaks are unexpectedly not directly resectable by the MRE11 complex. In contrast, breaks catalyzed by Cas12a are readily processed. Cas9, unlike Cas12a, bridges the broken ends, preventing DSB detection and processing by MRE11. We demonstrate that Cas9 must be dislocated after DNA cleavage to allow DNA end resection and repair. Using single molecule and bulk biochemical assays, we next find that the HLTF translocase directly removes Cas9 from broken ends, which allows DSB processing by DNA end resection or non-homologous end-joining machineries. Mechanistically, the activity of HLTF requires its HIRAN domain and the release of the 3'-end generated by the cleavage of the non-target DNA strand by the Cas9 RuvC domain. Consequently, HLTF removes the H840A but not the D10A Cas9 nickase. The removal of Cas9 H840A by HLTF explains the different cellular impact of the two Cas9 nickase variants in human cells, with potential implications for gene editing.
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Affiliation(s)
- Giordano Reginato
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland
| | - Maria Rosaria Dello Stritto
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland
| | - Yanbo Wang
- Department of Biophysics & Biophysical Chemistry, Johns Hopkins University, Baltimore, MD, 21205, USA
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | - Jingzhou Hao
- Department of Biophysics, Johns Hopkins University, Baltimore, MD21218, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Raphael Pavani
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Michael Schmitz
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Swagata Halder
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland
- Biological Systems Engineering, Plaksha University, Mohali, Punjab, 140306, India
| | - Vincent Morin
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Elda Cannavo
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland
| | - Ilaria Ceppi
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland
| | - Stefan Braunshier
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland
| | - Ananya Acharya
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland
| | - Virginie Ropars
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Jean-Baptiste Charbonnier
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Martin Jinek
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Andrè Nussenzweig
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Taekjip Ha
- Department of Biophysics & Biophysical Chemistry, Johns Hopkins University, Baltimore, MD, 21205, USA
- Department of Biophysics, Johns Hopkins University, Baltimore, MD21218, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA
- Howard Hughes Medical Institute, Boston, MA, 02115, USA
| | - Petr Cejka
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland.
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2
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Nicolas Y, Bret H, Cannavo E, Acharya A, Cejka P, Borde V, Guerois R. Molecular insights into the activation of Mre11-Rad50 endonuclease activity by Sae2/CtIP. Mol Cell 2024; 84:2223-2237.e4. [PMID: 38870937 DOI: 10.1016/j.molcel.2024.05.019] [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: 07/20/2023] [Revised: 02/25/2024] [Accepted: 05/20/2024] [Indexed: 06/15/2024]
Abstract
In Saccharomyces cerevisiae (S. cerevisiae), Mre11-Rad50-Xrs2 (MRX)-Sae2 nuclease activity is required for the resection of DNA breaks with secondary structures or protein blocks, while in humans, the MRE11-RAD50-NBS1 (MRN) homolog with CtIP is needed to initiate DNA end resection of all breaks. Phosphorylated Sae2/CtIP stimulates the endonuclease activity of MRX/N. Structural insights into the activation of the Mre11 nuclease are available only for organisms lacking Sae2/CtIP, so little is known about how Sae2/CtIP activates the nuclease ensemble. Here, we uncover the mechanism of Mre11 activation by Sae2 using a combination of AlphaFold2 structural modeling of biochemical and genetic assays. We show that Sae2 stabilizes the Mre11 nuclease in a conformation poised to cleave substrate DNA. Several designs of compensatory mutations establish how Sae2 activates MRX in vitro and in vivo, supporting the structural model. Finally, our study uncovers how human CtIP, despite considerable sequence divergence, employs a similar mechanism to activate MRN.
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Affiliation(s)
- Yoann Nicolas
- Institut Curie, PSL University, Sorbonne Université, CNRS UMR3244, Dynamics of Genetic Information, 75005 Paris, France
| | - Hélène Bret
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Elda Cannavo
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona 6500, Switzerland
| | - Ananya Acharya
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona 6500, Switzerland
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona 6500, Switzerland.
| | - Valérie Borde
- Institut Curie, PSL University, Sorbonne Université, CNRS UMR3244, Dynamics of Genetic Information, 75005 Paris, France.
| | - Raphaël Guerois
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France.
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3
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Acharya A, Bret H, Huang JW, Mütze M, Göse M, Kissling VM, Seidel R, Ciccia A, Guérois R, Cejka P. Mechanism of DNA unwinding by MCM8-9 in complex with HROB. Nat Commun 2024; 15:3584. [PMID: 38678026 PMCID: PMC11055865 DOI: 10.1038/s41467-024-47936-8] [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] [Received: 06/16/2023] [Accepted: 04/15/2024] [Indexed: 04/29/2024] Open
Abstract
HROB promotes the MCM8-9 helicase in DNA damage response. To understand how HROB activates MCM8-9, we defined their interaction interface. We showed that HROB makes important yet transient contacts with both MCM8 and MCM9, and binds the MCM8-9 heterodimer with the highest affinity. MCM8-9-HROB prefer branched DNA structures, and display low DNA unwinding processivity. MCM8-9 unwinds DNA as a hexamer that assembles from dimers on DNA in the presence of ATP. The hexamer involves two repeating protein-protein interfaces between the alternating MCM8 and MCM9 subunits. One of these interfaces is quite stable and forms an obligate heterodimer across which HROB binds. The other interface is labile and mediates hexamer assembly, independently of HROB. The ATPase site formed at the labile interface contributes disproportionally more to DNA unwinding than that at the stable interface. Here, we show that HROB promotes DNA unwinding downstream of MCM8-9 loading and ring formation on ssDNA.
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Affiliation(s)
- Ananya Acharya
- 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
| | - Hélène Bret
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Jen-Wei Huang
- Department of Genetics and Development, Institute for Cancer Genetics, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Martin Mütze
- Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig, 04103, Germany
| | - Martin Göse
- Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig, 04103, Germany
| | - Vera Maria Kissling
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, 8093, Switzerland
- Particles-Biology Interactions Laboratory, Department of Materials Meet Life, Swiss Federal Laboratories for Materials Science and Technology (Empa), St. Gallen, 9014, Switzerland
| | - Ralf Seidel
- Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig, 04103, Germany
| | - Alberto Ciccia
- Department of Genetics and Development, Institute for Cancer Genetics, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Raphaël Guérois
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France.
| | - 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.
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4
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Galanti L, Peritore M, Gnügge R, Cannavo E, Heipke J, Palumbieri MD, Steigenberger B, Symington LS, Cejka P, Pfander B. Dbf4-dependent kinase promotes cell cycle controlled resection of DNA double-strand breaks and repair by homologous recombination. Nat Commun 2024; 15:2890. [PMID: 38570537 PMCID: PMC10991553 DOI: 10.1038/s41467-024-46951-z] [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] [Received: 07/19/2023] [Accepted: 03/13/2024] [Indexed: 04/05/2024] Open
Abstract
DNA double-strand breaks (DSBs) can be repaired by several pathways. In eukaryotes, DSB repair pathway choice occurs at the level of DNA end resection and is controlled by the cell cycle. Upon cell cycle-dependent activation, cyclin-dependent kinases (CDKs) phosphorylate resection proteins and thereby stimulate end resection and repair by homologous recombination (HR). However, inability of CDK phospho-mimetic mutants to bypass this cell cycle regulation, suggests that additional cell cycle regulators may be important. Here, we identify Dbf4-dependent kinase (DDK) as a second major cell cycle regulator of DNA end resection. Using inducible genetic and chemical inhibition of DDK in budding yeast and human cells, we show that end resection and HR require activation by DDK. Mechanistically, DDK phosphorylates at least two resection nucleases in budding yeast: the Mre11 activator Sae2, which promotes resection initiation, as well as the Dna2 nuclease, which promotes resection elongation. Notably, synthetic activation of DDK allows limited resection and HR in G1 cells, suggesting that DDK is a key component of DSB repair pathway selection.
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Affiliation(s)
- Lorenzo Galanti
- Cell Biology, Dortmund Life Science Center (DOLCE), TU Dortmund University, Faculty of Chemistry and Chemical Biology, Dortmund, Germany
- Research Group DNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, Martinsried, Germany
- Genome Maintenance Mechanisms in Health and Disease, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
- Institute for Genome Stability in Aging and Disease, University of Cologne, Medical Faculty, CECAD Research Center, Cologne, Germany
| | - Martina Peritore
- Research Group DNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, Martinsried, Germany
- Genome Maintenance Mechanisms in Health and Disease, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
- Institute for Genome Stability in Aging and Disease, University of Cologne, Medical Faculty, CECAD Research Center, Cologne, Germany
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London, UK
| | - Robert Gnügge
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - Elda Cannavo
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera Italiana (USI), Bellinzona, Switzerland
| | - Johannes Heipke
- Cell Biology, Dortmund Life Science Center (DOLCE), TU Dortmund University, Faculty of Chemistry and Chemical Biology, Dortmund, Germany
- Research Group DNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, Martinsried, Germany
- Institute for Genome Stability in Aging and Disease, University of Cologne, Medical Faculty, CECAD Research Center, Cologne, Germany
| | - Maria Dilia Palumbieri
- Genome Maintenance Mechanisms in Health and Disease, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
- Institute for Genome Stability in Aging and Disease, University of Cologne, Medical Faculty, CECAD Research Center, Cologne, Germany
- Research Group of Proteomics and ADP-Ribosylation Signaling, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Barbara Steigenberger
- Mass Spectrometry Core Facility, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, USA
- Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY, USA
| | - Petr Cejka
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera Italiana (USI), Bellinzona, Switzerland
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Boris Pfander
- Cell Biology, Dortmund Life Science Center (DOLCE), TU Dortmund University, Faculty of Chemistry and Chemical Biology, Dortmund, Germany.
- Research Group DNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, Martinsried, Germany.
- Genome Maintenance Mechanisms in Health and Disease, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany.
- Institute for Genome Stability in Aging and Disease, University of Cologne, Medical Faculty, CECAD Research Center, Cologne, Germany.
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5
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Pizzul P, Casari E, Rinaldi C, Gnugnoli M, Mangiagalli M, Tisi R, Longhese MP. Rif2 interaction with Rad50 counteracts Tel1 functions in checkpoint signalling and DNA tethering by releasing Tel1 from MRX binding. Nucleic Acids Res 2024; 52:2355-2371. [PMID: 38180815 PMCID: PMC10954470 DOI: 10.1093/nar/gkad1246] [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: 07/15/2023] [Revised: 12/14/2023] [Accepted: 12/18/2023] [Indexed: 01/07/2024] Open
Abstract
The yeast Rif2 protein is known to inhibit Mre11 nuclease and the activation of Tel1 kinase through a short motif termed MIN, which binds the Rad50 subunit and simulates its ATPase activity in vitro. The mechanism by which Rif2 restrains Tel1 activation and the consequences of this inhibition at DNA double-strand breaks (DSBs) are poorly understood. In this study, we employed AlphaFold-Multimer modelling to pinpoint and validate the interaction surface between Rif2 MIN and Rad50. We also engineered the rif2-S6E mutation that enhances the inhibitory effect of Rif2 by increasing Rif2-Rad50 interaction. Unlike rif2Δ, the rif2-S6E mutation impairs hairpin cleavage. Furthermore, it diminishes Tel1 activation by inhibiting Tel1 binding to DSBs while leaving MRX association unchanged, indicating that Rif2 can directly inhibit Tel1 recruitment to DSBs. Additionally, Rif2S6E reduces Tel1-MRX interaction and increases stimulation of ATPase by Rad50, indicating that Rif2 binding to Rad50 induces an ADP-bound MRX conformation that is not suitable for Tel1 binding. The decreased Tel1 recruitment to DSBs in rif2-S6E cells impairs DSB end-tethering and this bridging defect is suppressed by expressing a Tel1 mutant variant that increases Tel1 persistence at DSBs, suggesting a direct role for Tel1 in the bridging of DSB ends.
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Affiliation(s)
- Paolo Pizzul
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Erika Casari
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Carlo Rinaldi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Marco Gnugnoli
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Marco Mangiagalli
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Renata Tisi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
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Roisné-Hamelin F, Liu HW, Taschner M, Li Y, Gruber S. Structural basis for plasmid restriction by SMC JET nuclease. Mol Cell 2024; 84:883-896.e7. [PMID: 38309275 DOI: 10.1016/j.molcel.2024.01.009] [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: 10/03/2023] [Revised: 12/06/2023] [Accepted: 01/09/2024] [Indexed: 02/05/2024]
Abstract
DNA loop-extruding SMC complexes play crucial roles in chromosome folding and DNA immunity. Prokaryotic SMC Wadjet (JET) complexes limit the spread of plasmids through DNA cleavage, yet the mechanisms for plasmid recognition are unresolved. We show that artificial DNA circularization renders linear DNA susceptible to JET nuclease cleavage. Unlike free DNA, JET cleaves immobilized plasmid DNA at a specific site, the plasmid-anchoring point, showing that the anchor hinders DNA extrusion but not DNA cleavage. Structures of plasmid-bound JetABC reveal two presumably stalled SMC motor units that are drastically rearranged from the resting state, together entrapping a U-shaped DNA segment, which is further converted to kinked V-shaped cleavage substrate by JetD nuclease binding. Our findings uncover mechanical bending of residual unextruded DNA as molecular signature for plasmid recognition and non-self DNA elimination. We moreover elucidate key elements of SMC loop extrusion, including the motor direction and the structure of a DNA-holding state.
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Affiliation(s)
- Florian Roisné-Hamelin
- Department of Fundamental Microbiology (DMF), Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), 1015 Lausanne, Switzerland
| | - Hon Wing Liu
- Department of Fundamental Microbiology (DMF), Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), 1015 Lausanne, Switzerland
| | - Michael Taschner
- Department of Fundamental Microbiology (DMF), Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), 1015 Lausanne, Switzerland
| | - Yan Li
- Department of Fundamental Microbiology (DMF), Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), 1015 Lausanne, Switzerland
| | - Stephan Gruber
- Department of Fundamental Microbiology (DMF), Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), 1015 Lausanne, Switzerland.
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7
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Möller C, Sharma R, Öz R, Reginato G, Cannavo E, Ceppi I, Sriram KK, Cejka P, Westerlund F. Xrs2/NBS1 promote end-bridging activity of the MRE11-RAD50 complex. Biochem Biophys Res Commun 2024; 695:149464. [PMID: 38217957 DOI: 10.1016/j.bbrc.2023.149464] [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: 10/10/2023] [Revised: 12/04/2023] [Accepted: 12/29/2023] [Indexed: 01/15/2024]
Abstract
DNA double strand breaks (DSBs) can be detrimental to the cell and need to be efficiently repaired. A first step in DSB repair is to bring the free ends in close proximity to enable ligation by non-homologous end-joining (NHEJ), while the more precise, but less available, repair by homologous recombination (HR) requires close proximity of a sister chromatid. The human MRE11-RAD50-NBS1 (MRN) complex, Mre11-Rad50-Xrs2 (MRX) in yeast, is involved in both repair pathways. Here we use nanofluidic channels to study, on the single DNA molecule level, how MRN, MRX and their constituents interact with long DNA and promote DNA bridging. Nanofluidics is a suitable method to study reactions on DNA ends since no anchoring of the DNA end(s) is required. We demonstrate that NBS1 and Xrs2 play important, but differing, roles in the DNA tethering by MRN and MRX. NBS1 promotes DNA bridging by MRN consistent with tethering of a repair template. MRX shows a "synapsis-like" DNA end-bridging, stimulated by the Xrs2 subunit. Our results highlight the different ways MRN and MRX bridge DNA, and the results are in agreement with their key roles in HR and NHEJ, respectively, and contribute to the understanding of the roles of NBS1 and Xrs2 in DSB repair.
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Affiliation(s)
- Carl Möller
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, SE, 41296, Sweden
| | - Rajhans Sharma
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, SE, 41296, Sweden
| | - Robin Öz
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, SE, 41296, Sweden
| | - Giordano Reginato
- Institute for Research in Biomedicine, Universitá della Svizzera Italiana, Bellinzona, CH 6500, Switzerland
| | - Elda Cannavo
- Institute for Research in Biomedicine, Universitá della Svizzera Italiana, Bellinzona, CH 6500, Switzerland
| | - Ilaria Ceppi
- Institute for Research in Biomedicine, Universitá della Svizzera Italiana, Bellinzona, CH 6500, Switzerland
| | - K K Sriram
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, SE, 41296, Sweden
| | - Petr Cejka
- Institute for Research in Biomedicine, Universitá della Svizzera Italiana, Bellinzona, CH 6500, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH) Zürich, Switzerland
| | - Fredrik Westerlund
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, SE, 41296, Sweden.
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8
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Bossaert M, Moreno A, Peixoto A, Pillaire MJ, Chanut P, Frit P, Calsou P, Loparo JJ, Britton S. Identification of the main barriers to Ku accumulation in chromatin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.03.574002. [PMID: 38260538 PMCID: PMC10802386 DOI: 10.1101/2024.01.03.574002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Repair of DNA double strand breaks by the non-homologous end-joining pathway is initiated by the binding of Ku to DNA ends. Given its high affinity for ends, multiple Ku proteins load onto linear DNAs in vitro. However, in cells, Ku loading is limited to ~1-2 molecules per DNA end. The mechanisms enforcing this limit are currently unknown. Here we show that the catalytic subunit of the DNA-dependent protein kinase (DNA-PKcs), but not its protein kinase activity, is required to prevent excessive Ku entry into chromatin. Ku accumulation is further restricted by two mechanisms: a neddylation/FBXL12-dependent process which actively removes loaded Ku molecules throughout the cell cycle and a CtIP/ATM-dependent mechanism which operates in S-phase. Finally, we demonstrate that the misregulation of Ku loading leads to impaired transcription in the vicinity of DNA ends. Together our data shed light on the multiple layers of coordinated mechanisms operating to prevent Ku from invading chromatin and interfering with other DNA transactions.
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Affiliation(s)
- Madeleine Bossaert
- Institut de Pharmacologie et Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
- Equipe labélisée la Ligue contre le Cancer 2018
| | - Andrew Moreno
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115
| | - Antonio Peixoto
- Institut de Pharmacologie et Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
- Equipe labélisée la Ligue contre le Cancer 2018
| | - Marie-Jeanne Pillaire
- Institut de Pharmacologie et Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
- Equipe labélisée la Ligue contre le Cancer 2018
| | - Pauline Chanut
- Institut de Pharmacologie et Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
- Equipe labélisée la Ligue contre le Cancer 2018
| | - Philippe Frit
- Institut de Pharmacologie et Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
- Equipe labélisée la Ligue contre le Cancer 2018
| | - Patrick Calsou
- Institut de Pharmacologie et Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
- Equipe labélisée la Ligue contre le Cancer 2018
| | - Joseph John Loparo
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115
| | - Sébastien Britton
- Institut de Pharmacologie et Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
- Equipe labélisée la Ligue contre le Cancer 2018
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9
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Bader AS, Bushell M. iMUT-seq: high-resolution DSB-induced mutation profiling reveals prevalent homologous-recombination dependent mutagenesis. Nat Commun 2023; 14:8419. [PMID: 38110444 PMCID: PMC10728174 DOI: 10.1038/s41467-023-44167-1] [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] [Received: 04/01/2022] [Accepted: 12/04/2023] [Indexed: 12/20/2023] Open
Abstract
DNA double-strand breaks (DSBs) are the most mutagenic form of DNA damage, and play a significant role in cancer biology, neurodegeneration and aging. However, studying DSB-induced mutagenesis is limited by our current approaches. Here, we describe iMUT-seq, a technique that profiles DSB-induced mutations at high-sensitivity and single-nucleotide resolution around endogenous DSBs. By depleting or inhibiting 20 DSB-repair factors we define their mutational signatures in detail, revealing insights into the mechanisms of DSB-induced mutagenesis. Notably, we find that homologous-recombination (HR) is more mutagenic than previously thought, inducing prevalent base substitutions and mononucleotide deletions at distance from the break due to DNA-polymerase errors. Simultaneously, HR reduces translocations, suggesting a primary role of HR is specifically the prevention of genomic rearrangements. The results presented here offer fundamental insights into DSB-induced mutagenesis and have significant implications for our understanding of cancer biology and the development of DDR-targeting chemotherapeutics.
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Affiliation(s)
- Aldo S Bader
- Cancer Research UK Beatson Institute, Glasgow, G61 1BD, UK.
- Cancer Research UK/CI, University of Cambridge, Li Ka Shing Centre, Cambridge, CB2 0RE, UK.
- The Gurdon Institute, University of Cambridge, Biochemistry, Cambridge, UK.
| | - Martin Bushell
- Cancer Research UK Beatson Institute, Glasgow, G61 1BD, UK.
- Institute of Cancer Sciences, University of Glasgow, Glasgow, G61 1QH, UK.
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10
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Casari E, Pizzul P, Rinaldi C, Gnugnoli M, Clerici M, Longhese MP. The PP2A phosphatase counteracts the function of the 9-1-1 axis in checkpoint activation. Cell Rep 2023; 42:113360. [PMID: 38007689 DOI: 10.1016/j.celrep.2023.113360] [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: 06/03/2023] [Revised: 09/25/2023] [Accepted: 10/13/2023] [Indexed: 11/27/2023] Open
Abstract
DNA damage elicits a checkpoint response depending on the Mec1/ATR kinase, which detects the presence of single-stranded DNA and activates the effector kinase Rad53/CHK2. In Saccharomyces cerevisiae, one of the signaling circuits leading to Rad53 activation involves the evolutionarily conserved 9-1-1 complex, which acts as a platform for the binding of Dpb11 and Rad9 (referred to as the 9-1-1 axis) to generate a protein complex that allows Mec1 activation. By examining the effects of both loss-of-function and hypermorphic mutations, here, we show that the Cdc55 and Tpd3 subunits of the PP2A phosphatase counteract activation of the 9-1-1 axis. The lack of this inhibitory function results in DNA-damage sensitivity, sustained checkpoint-mediated cell-cycle arrest, and impaired resection of DNA double-strand breaks. This PP2A anti-checkpoint role depends on the capacity of Cdc55 to interact with Ddc1 and to counteract Ddc1-Dpb11 complex formation by preventing Dpb11 recognition of Ddc1 phosphorylated on Thr602.
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Affiliation(s)
- Erika Casari
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Paolo Pizzul
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Carlo Rinaldi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Marco Gnugnoli
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Michela Clerici
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy.
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11
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Hale A, Dhoonmoon A, Straka J, Nicolae CM, Moldovan GL. Multi-step processing of replication stress-derived nascent strand DNA gaps by MRE11 and EXO1 nucleases. Nat Commun 2023; 14:6265. [PMID: 37805499 PMCID: PMC10560291 DOI: 10.1038/s41467-023-42011-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 09/27/2023] [Indexed: 10/09/2023] Open
Abstract
Accumulation of single stranded DNA (ssDNA) gaps in the nascent strand during DNA replication has been associated with cytotoxicity and hypersensitivity to genotoxic stress, particularly upon inactivation of the BRCA tumor suppressor pathway. However, how ssDNA gaps contribute to genotoxicity is not well understood. Here, we describe a multi-step nucleolytic processing of replication stress-induced ssDNA gaps which converts them into cytotoxic double stranded DNA breaks (DSBs). We show that ssDNA gaps are extended bidirectionally by MRE11 in the 3'-5' direction and by EXO1 in the 5'-3' direction, in a process which is suppressed by the BRCA pathway. Subsequently, the parental strand at the ssDNA gap is cleaved by the MRE11 endonuclease generating a double strand break. We also show that exposure to bisphenol A (BPA) and diethylhexyl phthalate (DEHP), which are widespread environmental contaminants due to their use in plastics manufacturing, causes nascent strand ssDNA gaps during replication. These gaps are processed through the same mechanism described above to generate DSBs. Our work sheds light on both the relevance of ssDNA gaps as major determinants of genomic instability, as well as the mechanism through which they are processed to generate genomic instability and cytotoxicity.
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Affiliation(s)
- Anastasia Hale
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Ashna Dhoonmoon
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Joshua Straka
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Claudia M Nicolae
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
| | - George-Lucian Moldovan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
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12
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Deshpande RA, Marin-Gonzalez A, Barnes HK, Woolley PR, Ha T, Paull TT. Genome-wide analysis of DNA-PK-bound MRN cleavage products supports a sequential model of DSB repair pathway choice. Nat Commun 2023; 14:5759. [PMID: 37717054 PMCID: PMC10505227 DOI: 10.1038/s41467-023-41544-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 09/07/2023] [Indexed: 09/18/2023] Open
Abstract
The Mre11-Rad50-Nbs1 (MRN) complex recognizes and processes DNA double-strand breaks for homologous recombination by performing short-range removal of 5' strands. Endonucleolytic processing by MRN requires a stably bound protein at the break site-a role we postulate is played by DNA-dependent protein kinase (DNA-PK) in mammals. Here we interrogate sites of MRN-dependent processing by identifying sites of CtIP association and by sequencing DNA-PK-bound DNA fragments that are products of MRN cleavage. These intermediates are generated most efficiently when DNA-PK is catalytically blocked, yielding products within 200 bp of the break site, whereas DNA-PK products in the absence of kinase inhibition show greater dispersal. Use of light-activated Cas9 to induce breaks facilitates temporal resolution of DNA-PK and Mre11 binding, showing that both complexes bind to DNA ends before release of DNA-PK-bound products. These results support a sequential model of double-strand break repair involving collaborative interactions between homologous and non-homologous repair complexes.
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Affiliation(s)
| | - Alberto Marin-Gonzalez
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Howard Hughes Medical Institute, Baltimore, MD, 21205, USA
| | - Hannah K Barnes
- The Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Phillip R Woolley
- The Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Howard Hughes Medical Institute, Baltimore, MD, 21205, USA
| | - Tanya T Paull
- The Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA.
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13
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Su J, Su Q, Hu S, Ruan X, Ouyang S. Research Progress on the Anti-Aging Potential of the Active Components of Ginseng. Nutrients 2023; 15:3286. [PMID: 37571224 PMCID: PMC10421173 DOI: 10.3390/nu15153286] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 07/13/2023] [Accepted: 07/21/2023] [Indexed: 08/13/2023] Open
Abstract
Aging is a cellular state characterized by a permanent cessation of cell division and evasion of apoptosis. DNA damage, metabolic dysfunction, telomere damage, and mitochondrial dysfunction are the main factors associated with senescence. Aging increases β-galactosidase activity, enhances cell spreading, and induces Lamin B1 loss, which further accelerate the aging process. It is associated with a variety of diseases, such as Alzheimer's disease, Parkinson's, type 2 diabetes, and chronic inflammation. Ginseng is a traditional Chinese medicine with anti-aging effects. The active components of ginseng, including saponins, polysaccharides, and active peptides, have antioxidant, anti-apoptotic, neuroprotective, and age-delaying effects. DNA damage is the main factor associated with aging, and the mechanism through which the active ingredients of ginseng reduce DNA damage and delay aging has not been comprehensively described. This review focuses on the anti-aging mechanisms of the active ingredients of ginseng. Furthermore, it broadens the scope of ideas for further research on natural products and aging.
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Affiliation(s)
- Jingqian Su
- Fujian Key Laboratory of Innate Immune Biology, Biomedical Research Center of South China, College of Life Sciences, Fujian Normal University, Fuzhou 350117, China; (Q.S.); (S.H.)
- Provincial University Key Laboratory of Microbial Pathogenesis and Interventions, College of Life Sciences, Fujian Normal University, Fuzhou 350117, China
| | - Qiaofen Su
- Fujian Key Laboratory of Innate Immune Biology, Biomedical Research Center of South China, College of Life Sciences, Fujian Normal University, Fuzhou 350117, China; (Q.S.); (S.H.)
- Provincial University Key Laboratory of Microbial Pathogenesis and Interventions, College of Life Sciences, Fujian Normal University, Fuzhou 350117, China
| | - Shan Hu
- Fujian Key Laboratory of Innate Immune Biology, Biomedical Research Center of South China, College of Life Sciences, Fujian Normal University, Fuzhou 350117, China; (Q.S.); (S.H.)
- Provincial University Key Laboratory of Microbial Pathogenesis and Interventions, College of Life Sciences, Fujian Normal University, Fuzhou 350117, China
| | - Xinglin Ruan
- Department of Neurology, Fujian Medical University Union Hospital, Fuzhou 350001, China;
| | - Songying Ouyang
- Fujian Key Laboratory of Innate Immune Biology, Biomedical Research Center of South China, College of Life Sciences, Fujian Normal University, Fuzhou 350117, China; (Q.S.); (S.H.)
- Provincial University Key Laboratory of Microbial Pathogenesis and Interventions, College of Life Sciences, Fujian Normal University, Fuzhou 350117, China
- Key Laboratory of OptoElectronic Science and Technology for Medicine of the Ministry of Education, Fujian Normal University, Fuzhou 350117, China
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14
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Gnügge R, Reginato G, Cejka P, Symington LS. Sequence and chromatin features guide DNA double-strand break resection initiation. Mol Cell 2023; 83:1237-1250.e15. [PMID: 36917982 PMCID: PMC10131398 DOI: 10.1016/j.molcel.2023.02.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 01/09/2023] [Accepted: 02/09/2023] [Indexed: 03/14/2023]
Abstract
DNA double-strand breaks (DSBs) are cytotoxic genome lesions that must be accurately and efficiently repaired to ensure genome integrity. In yeast, the Mre11-Rad50-Xrs2 (MRX) complex nicks 5'-terminated DSB ends to initiate nucleolytic processing of DSBs for repair by homologous recombination. How MRX-DNA interactions support 5' strand-specific nicking and how nicking is influenced by the chromatin context have remained elusive. Using a deep sequencing-based assay, we mapped MRX nicks at single-nucleotide resolution next to multiple DSBs in the yeast genome. We observed that the DNA end-binding Ku70-Ku80 complex directed DSB-proximal nicks and that repetitive MRX cleavage extended the length of resection tracts. We identified a sequence motif and a DNA meltability profile that is preferentially nicked by MRX. Furthermore, we found that nucleosomes as well as transcription impeded MRX incisions. Our findings suggest that local DNA sequence and chromatin features shape the activity of this central DSB repair complex.
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Affiliation(s)
- Robert Gnügge
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.
| | - Giordano Reginato
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8093 Zürich, Switzerland; Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, 6500 Bellinzona, Switzerland
| | - Petr Cejka
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8093 Zürich, Switzerland; Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, 6500 Bellinzona, Switzerland
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA; Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY 10032, USA.
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15
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Mre11-Rad50: the DNA end game. Biochem Soc Trans 2023; 51:527-538. [PMID: 36892213 DOI: 10.1042/bst20220754] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/09/2023] [Accepted: 02/17/2023] [Indexed: 03/10/2023]
Abstract
The Mre11-Rad50-(Nbs1/Xrs2) complex is an evolutionarily conserved factor for the repair of DNA double-strand breaks and other DNA termini in all kingdoms of life. It is an intricate DNA associated molecular machine that cuts, among other functions, a large variety of free and obstructed DNA termini for DNA repair by end joining or homologous recombination, yet leaves undamaged DNA intact. Recent years have brought progress in both the structural and functional analyses of Mre11-Rad50 orthologs, revealing mechanisms of DNA end recognition, endo/exonuclease activities, nuclease regulation and DNA scaffolding. Here, I review our current understanding and recent progress on the functional architecture Mre11-Rad50 and how this chromosome associated coiled-coil ABC ATPase acts as DNA topology specific endo-/exonuclease.
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16
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Rinaldi C, Pizzul P, Casari E, Mangiagalli M, Tisi R, Longhese MP. The Ku complex promotes DNA end-bridging and this function is antagonized by Tel1/ATM kinase. Nucleic Acids Res 2023; 51:1783-1802. [PMID: 36762474 PMCID: PMC9976877 DOI: 10.1093/nar/gkad062] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 01/18/2023] [Accepted: 01/20/2023] [Indexed: 02/11/2023] Open
Abstract
DNA double-strand breaks (DSBs) can be repaired by either homologous recombination (HR) or non-homologous end-joining (NHEJ). NHEJ is induced by the binding to DSBs of the Ku70-Ku80 heterodimer, which acts as a hub for the recruitment of downstream NHEJ components. An important issue in DSB repair is the maintenance of the DSB ends in close proximity, a function that in yeast involves the MRX complex and Sae2. Here, we provide evidence that Ku contributes to keep the DNA ends tethered to each other. The ku70-C85Y mutation, which increases Ku affinity for DNA and its persistence very close to the DSB ends, enhances DSB end-tethering and suppresses the end-tethering defect of sae2Δ cells. Impairing histone removal around DSBs either by eliminating Tel1 kinase activity or nucleosome remodelers enhances Ku persistence at DSBs and DSB bridging, suggesting that Tel1 antagonizes the Ku function in supporting end-tethering by promoting nucleosome removal and possibly Ku sliding inwards. As Ku provides a block to DSB resection, this Tel1 function can be important to regulate the mode by which DSBs are repaired.
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Affiliation(s)
- Carlo Rinaldi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Paolo Pizzul
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Erika Casari
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Marco Mangiagalli
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Renata Tisi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milano, Italy
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17
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RNA:DNA hybrids from Okazaki fragments contribute to establish the Ku-mediated barrier to replication-fork degradation. Mol Cell 2023; 83:1061-1074.e6. [PMID: 36868227 DOI: 10.1016/j.molcel.2023.02.008] [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: 12/14/2021] [Revised: 12/09/2022] [Accepted: 02/04/2023] [Indexed: 03/05/2023]
Abstract
Nonhomologous end-joining (NHEJ) factors act in replication-fork protection, restart, and repair. Here, we identified a mechanism related to RNA:DNA hybrids to establish the NHEJ factor Ku-mediated barrier to nascent strand degradation in fission yeast. RNase H activities promote nascent strand degradation and replication restart, with a prominent role of RNase H2 in processing RNA:DNA hybrids to overcome the Ku barrier to nascent strand degradation. RNase H2 cooperates with the MRN-Ctp1 axis to sustain cell resistance to replication stress in a Ku-dependent manner. Mechanistically, the need of RNaseH2 in nascent strand degradation requires the primase activity that allows establishing the Ku barrier to Exo1, whereas impairing Okazaki fragment maturation reinforces the Ku barrier. Finally, replication stress induces Ku foci in a primase-dependent manner and favors Ku binding to RNA:DNA hybrids. We propose a function for the RNA:DNA hybrid originating from Okazaki fragments in controlling the Ku barrier specifying nuclease requirement to engage fork resection.
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18
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Frigerio C, Di Nisio E, Galli M, Colombo CV, Negri R, Clerici M. The Chromatin Landscape around DNA Double-Strand Breaks in Yeast and Its Influence on DNA Repair Pathway Choice. Int J Mol Sci 2023; 24:ijms24043248. [PMID: 36834658 PMCID: PMC9967470 DOI: 10.3390/ijms24043248] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 01/21/2023] [Accepted: 02/01/2023] [Indexed: 02/09/2023] Open
Abstract
DNA double-strand breaks (DSBs) are harmful DNA lesions, which elicit catastrophic consequences for genome stability if not properly repaired. DSBs can be repaired by either non-homologous end joining (NHEJ) or homologous recombination (HR). The choice between these two pathways depends on which proteins bind to the DSB ends and how their action is regulated. NHEJ initiates with the binding of the Ku complex to the DNA ends, while HR is initiated by the nucleolytic degradation of the 5'-ended DNA strands, which requires several DNA nucleases/helicases and generates single-stranded DNA overhangs. DSB repair occurs within a precisely organized chromatin environment, where the DNA is wrapped around histone octamers to form the nucleosomes. Nucleosomes impose a barrier to the DNA end processing and repair machinery. Chromatin organization around a DSB is modified to allow proper DSB repair either by the removal of entire nucleosomes, thanks to the action of chromatin remodeling factors, or by post-translational modifications of histones, thus increasing chromatin flexibility and the accessibility of repair enzymes to the DNA. Here, we review histone post-translational modifications occurring around a DSB in the yeast Saccharomyces cerevisiae and their role in DSB repair, with particular attention to DSB repair pathway choice.
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Affiliation(s)
- Chiara Frigerio
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milan, Italy
| | - Elena Di Nisio
- Department of Biology and Biotechnologies “C. Darwin”, Sapienza University of Rome, 00185 Rome, Italy
| | - Michela Galli
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milan, Italy
| | - Chiara Vittoria Colombo
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milan, Italy
| | - Rodolfo Negri
- Department of Biology and Biotechnologies “C. Darwin”, Sapienza University of Rome, 00185 Rome, Italy
- Institute of Molecular Biology and Pathology (IBPM), National Research Council (CNR) of Italy, 00185 Rome, Italy
- Correspondence: (R.N.); (M.C.)
| | - Michela Clerici
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milan, Italy
- Correspondence: (R.N.); (M.C.)
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19
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Ceppi I, Cannavo E, Bret H, Camarillo R, Vivalda F, Thakur RS, Romero-Franco A, Sartori AA, Huertas P, Guérois R, Cejka P. PLK1 regulates CtIP and DNA2 interplay in long-range DNA end resection. Genes Dev 2023; 37:119-135. [PMID: 36746606 PMCID: PMC10069449 DOI: 10.1101/gad.349981.122] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 01/12/2023] [Indexed: 02/08/2023]
Abstract
DNA double-strand break (DSB) repair is initiated by DNA end resection. CtIP acts in short-range resection to stimulate MRE11-RAD50-NBS1 (MRN) to endonucleolytically cleave 5'-terminated DNA to bypass protein blocks. CtIP also promotes the DNA2 helicase-nuclease to accelerate long-range resection downstream from MRN. Here, using AlphaFold2, we identified CtIP-F728E-Y736E as a separation-of-function mutant that is still proficient in conjunction with MRN but is not able to stimulate ssDNA degradation by DNA2. Accordingly, CtIP-F728E-Y736E impairs physical interaction with DNA2. Cellular assays revealed that CtIP-F728E-Y736E cells exhibit reduced DSB-dependent chromatin-bound RPA, impaired long-range resection, and increased sensitivity to DSB-inducing drugs. Previously, CtIP was shown to be targeted by PLK1 to inhibit long-range resection, yet the underlying mechanism was unclear. We show that the DNA2-interacting region in CtIP includes the PLK1 target site at S723. The integrity of S723 in CtIP is necessary for the stimulation of DNA2, and phosphorylation of CtIP by PLK1 in vitro is consequently inhibitory, explaining why PLK1 restricts long-range resection. Our data support a model in which CDK-dependent phosphorylation of CtIP activates resection by MRN in S phase, and PLK1-mediated phosphorylation of CtIP disrupts CtIP stimulation of DNA2 to attenuate long-range resection later at G2/M.
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Affiliation(s)
- Ilaria Ceppi
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona 6500, Switzerland
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich 8093, Switzerland
| | - Elda Cannavo
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona 6500, Switzerland
| | - Hélène Bret
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette 91190, France
| | - Rosa Camarillo
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla 41080, Spain
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide, Sevilla 41092, Spain
| | - Francesca Vivalda
- Institute of Molecular Cancer Research, University of Zürich, Zürich 8057, Switzerland
| | - Roshan Singh Thakur
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona 6500, Switzerland
| | - Amador Romero-Franco
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla 41080, Spain
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide, Sevilla 41092, Spain
| | - Alessandro A Sartori
- Institute of Molecular Cancer Research, University of Zürich, Zürich 8057, Switzerland
| | - Pablo Huertas
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla 41080, Spain
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide, Sevilla 41092, Spain
| | - Raphaël Guérois
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette 91190, France
| | - Petr Cejka
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona 6500, Switzerland;
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich 8093, Switzerland
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20
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Rotheneder M, Stakyte K, van de Logt E, Bartho JD, Lammens K, Fan Y, Alt A, Kessler B, Jung C, Roos WP, Steigenberger B, Hopfner KP. Cryo-EM structure of the Mre11-Rad50-Nbs1 complex reveals the molecular mechanism of scaffolding functions. Mol Cell 2023; 83:167-185.e9. [PMID: 36577401 DOI: 10.1016/j.molcel.2022.12.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 10/14/2022] [Accepted: 12/03/2022] [Indexed: 12/28/2022]
Abstract
The DNA double-strand break repair complex Mre11-Rad50-Nbs1 (MRN) detects and nucleolytically processes DNA ends, activates the ATM kinase, and tethers DNA at break sites. How MRN can act both as nuclease and scaffold protein is not well understood. The cryo-EM structure of MRN from Chaetomium thermophilum reveals a 2:2:1 complex with a single Nbs1 wrapping around the autoinhibited Mre11 nuclease dimer. MRN has two DNA-binding modes, one ATP-dependent mode for loading onto DNA ends and one ATP-independent mode through Mre11's C terminus, suggesting how it may interact with DSBs and intact DNA. MRNs two 60-nm-long coiled-coil domains form a linear rod structure, the apex of which is assembled by the two joined zinc-hook motifs. Apices from two MRN complexes can further dimerize, forming 120-nm spanning MRN-MRN structures. Our results illustrate the architecture of MRN and suggest how it mechanistically integrates catalytic and tethering functions.
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Affiliation(s)
- Matthias Rotheneder
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Kristina Stakyte
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Erik van de Logt
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Joseph D Bartho
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Katja Lammens
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Yilan Fan
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Aaron Alt
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Brigitte Kessler
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Christophe Jung
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Wynand P Roos
- Institute for Toxicology, Johannes-Gutenberg-Universität, Mainz, Germany
| | - Barbara Steigenberger
- Mass Spectrometry Core Facility, Max-Planck-Institute of Biochemistry, Martinsried, Germany
| | - Karl-Peter Hopfner
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany.
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21
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Casari E, Gnugnoli M, Rinaldi C, Pizzul P, Colombo CV, Bonetti D, Longhese MP. To Fix or Not to Fix: Maintenance of Chromosome Ends Versus Repair of DNA Double-Strand Breaks. Cells 2022; 11:cells11203224. [PMID: 36291091 PMCID: PMC9601279 DOI: 10.3390/cells11203224] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/07/2022] [Accepted: 10/12/2022] [Indexed: 02/08/2023] Open
Abstract
Early work by Muller and McClintock discovered that the physical ends of linear chromosomes, named telomeres, possess an inherent ability to escape unwarranted fusions. Since then, extensive research has shown that this special feature relies on specialized proteins and structural properties that confer identity to the chromosome ends, thus allowing cells to distinguish them from intrachromosomal DNA double-strand breaks. Due to the inability of conventional DNA replication to fully replicate the chromosome ends and the downregulation of telomerase in most somatic human tissues, telomeres shorten as cells divide and lose this protective capacity. Telomere attrition causes the activation of the DNA damage checkpoint that leads to a cell-cycle arrest and the entering of cells into a nondividing state, called replicative senescence, that acts as a barrier against tumorigenesis. However, downregulation of the checkpoint overcomes this barrier and leads to further genomic instability that, if coupled with re-stabilization of telomeres, can drive tumorigenesis. This review focuses on the key experiments that have been performed in the model organism Saccharomyces cerevisiae to uncover the mechanisms that protect the chromosome ends from eliciting a DNA damage response, the conservation of these pathways in mammals, as well as the consequences of their loss in human cancer.
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22
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Zhang T, Yang H, Zhou Z, Bai Y, Wang J, Wang W. Crosstalk between SUMOylation and ubiquitylation controls DNA end resection by maintaining MRE11 homeostasis on chromatin. Nat Commun 2022; 13:5133. [PMID: 36050397 PMCID: PMC9436968 DOI: 10.1038/s41467-022-32920-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 08/24/2022] [Indexed: 11/09/2022] Open
Abstract
DNA end resection is delicately regulated through various types of post-translational modifications to initiate homologous recombination, but the involvement of SUMOylation in this process remains incompletely understood. Here, we show that MRE11 requires SUMOylation to shield it from ubiquitin-mediated degradation when resecting damaged chromatin. Upon DSB induction, PIAS1 promotes MRE11 SUMOylation on chromatin to initiate DNA end resection. Then, MRE11 is deSUMOylated by SENP3 mainly after it has moved away from DSB sites. SENP3 deficiency results in MRE11 degradation failure and accumulation on chromatin, causing genome instability. We further show that cancer-related MRE11 mutants with impaired SUMOylation exhibit compromised DNA repair ability. Thus, we demonstrate that MRE11 SUMOylation in coordination with ubiquitylation is dynamically controlled by PIAS1 and SENP3 to facilitate DNA end resection and maintain genome stability. DNA end resection initiating DNA repair by homologous recombination needs to be delicately regulated. This study shows the interplay between SUMOylation and ubiquitylation maintains MRE11 homeostasis on chromatin, thus facilitating genome stability.
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Affiliation(s)
- Tao Zhang
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Han Yang
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Zenan Zhou
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Yongtai Bai
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Jiadong Wang
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Weibin Wang
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China.
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23
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Halder S, Sanchez A, Ranjha L, Reginato G, Ceppi I, Acharya A, Anand R, Cejka P. Double-stranded DNA binding function of RAD51 in DNA protection and its regulation by BRCA2. Mol Cell 2022; 82:3553-3565.e5. [PMID: 36070766 DOI: 10.1016/j.molcel.2022.08.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 06/16/2022] [Accepted: 08/10/2022] [Indexed: 11/26/2022]
Abstract
RAD51 and the breast cancer suppressor BRCA2 have critical functions in DNA double-strand (dsDNA) break repair by homologous recombination and the protection of newly replicated DNA from nucleolytic degradation. The recombination function of RAD51 requires its binding to single-stranded DNA (ssDNA), whereas binding to dsDNA is inhibitory. Using reconstituted MRE11-, EXO1-, and DNA2-dependent nuclease reactions, we show that the protective function of RAD51 unexpectedly depends on its binding to dsDNA. The BRC4 repeat of BRCA2 abrogates RAD51 binding to dsDNA and accordingly impairs the function of RAD51 in protection. The BRCA2 C-terminal RAD51-binding segment (TR2) acts in a dominant manner to overcome the effect of BRC4. Mechanistically, TR2 stabilizes RAD51 binding to dsDNA, even in the presence of BRC4, promoting DNA protection. Our data suggest that RAD51's dsDNA-binding capacity may have evolved together with its function in replication fork protection and provide a mechanistic basis for the DNA-protection function of BRCA2.
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Affiliation(s)
- Swagata Halder
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, 6500 Bellinzona, Switzerland
| | - Aurore Sanchez
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, 6500 Bellinzona, Switzerland
| | - Lepakshi Ranjha
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, 6500 Bellinzona, Switzerland
| | - Giordano Reginato
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, 6500 Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8049 Zürich, Switzerland
| | - Ilaria Ceppi
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, 6500 Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8049 Zürich, Switzerland
| | - Ananya Acharya
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, 6500 Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8049 Zürich, Switzerland
| | - Roopesh Anand
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, 6500 Bellinzona, Switzerland
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, 6500 Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8049 Zürich, Switzerland.
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24
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Dhoonmoon A, Nicolae CM, Moldovan GL. The KU-PARP14 axis differentially regulates DNA resection at stalled replication forks by MRE11 and EXO1. Nat Commun 2022; 13:5063. [PMID: 36030235 PMCID: PMC9420157 DOI: 10.1038/s41467-022-32756-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 08/12/2022] [Indexed: 11/24/2022] Open
Abstract
Suppression of nascent DNA degradation has emerged as an essential role of the BRCA pathway in genome protection. In BRCA-deficient cells, the MRE11 nuclease is responsible for both resection of reversed replication forks, and accumulation of single stranded DNA gaps behind forks. Here, we show that the mono-ADP-ribosyltransferase PARP14 is a critical co-factor of MRE11. PARP14 is recruited to nascent DNA upon replication stress in BRCA-deficient cells, and through its catalytic activity, mediates the engagement of MRE11. Loss or inhibition of PARP14 suppresses MRE11-mediated fork degradation and gap accumulation, and promotes genome stability and chemoresistance of BRCA-deficient cells. Moreover, we show that the KU complex binds reversed forks and protects them against EXO1-catalyzed degradation. KU recruits the PARP14-MRE11 complex, which initiates partial resection to release KU and allow long-range resection by EXO1. Our work identifies a multistep process of nascent DNA processing at stalled replication forks in BRCA-deficient cells. Protection of replication forks against nucleolytic degradation is crucial for genome stability. Here, Dhoonmoon et al identify PARP14 and the KU complex as essential regulators of fork degradation by MRE11 and EXO1 nucleases in BRCA-deficient cells.
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Affiliation(s)
- Ashna Dhoonmoon
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Claudia M Nicolae
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
| | - George-Lucian Moldovan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
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25
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Structural mechanism of endonucleolytic processing of blocked DNA ends and hairpins by Mre11-Rad50. Mol Cell 2022; 82:3513-3522.e6. [DOI: 10.1016/j.molcel.2022.07.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 06/10/2022] [Accepted: 07/23/2022] [Indexed: 11/17/2022]
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26
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Kissling VM, Reginato G, Bianco E, Kasaciunaite K, Tilma J, Cereghetti G, Schindler N, Lee SS, Guérois R, Luke B, Seidel R, Cejka P, Peter M. Mre11-Rad50 oligomerization promotes DNA double-strand break repair. Nat Commun 2022; 13:2374. [PMID: 35501303 PMCID: PMC9061753 DOI: 10.1038/s41467-022-29841-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 04/01/2022] [Indexed: 11/08/2022] Open
Abstract
The conserved Mre11-Rad50 complex is crucial for the detection, signaling, end tethering and processing of DNA double-strand breaks. While it is known that Mre11-Rad50 foci formation at DNA lesions accompanies repair, the underlying molecular assembly mechanisms and functional implications remained unclear. Combining pathway reconstitution in electron microscopy, biochemical assays and genetic studies, we show that S. cerevisiae Mre11-Rad50 with or without Xrs2 forms higher-order assemblies in solution and on DNA. Rad50 mediates such oligomerization, and mutations in a conserved Rad50 beta-sheet enhance or disrupt oligomerization. We demonstrate that Mre11-Rad50-Xrs2 oligomerization facilitates foci formation, DNA damage signaling, repair, and telomere maintenance in vivo. Mre11-Rad50 oligomerization does not affect its exonuclease activity but drives endonucleolytic cleavage at multiple sites on the 5'-DNA strand near double-strand breaks. Interestingly, mutations in the human RAD50 beta-sheet are linked to hereditary cancer predisposition and our findings might provide insights into their potential role in chemoresistance.
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Affiliation(s)
- Vera M Kissling
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8093, Zürich, Switzerland
| | - Giordano Reginato
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8093, Zürich, Switzerland
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, 6500, Bellinzona, Switzerland
| | - Eliana Bianco
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8093, Zürich, Switzerland
| | - Kristina Kasaciunaite
- Peter Debye Institute for Soft Matter Physics, Universität Leipzig, 04103, Leipzig, Germany
| | - Janny Tilma
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8093, Zürich, Switzerland
| | - Gea Cereghetti
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8093, Zürich, Switzerland
| | - Natalie Schindler
- Institute for Developmental and Neurobiology (IDN), Johannes Gutenberg University, 55128, Mainz, Germany
| | - Sung Sik Lee
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8093, Zürich, Switzerland
- Scientific Center for Optical and Electron Microscopy, Eidgenössische Technische Hochschule (ETH), 8093, Zürich, Switzerland
| | - Raphaël Guérois
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, CNRS, Université Paris-Sud, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - Brian Luke
- Institute for Developmental and Neurobiology (IDN), Johannes Gutenberg University, 55128, Mainz, Germany
- Institute of Molecular Biology (IMB), 55128, Mainz, Germany
| | - Ralf Seidel
- Peter Debye Institute for Soft Matter Physics, Universität Leipzig, 04103, Leipzig, Germany
| | - Petr Cejka
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8093, Zürich, Switzerland.
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, 6500, Bellinzona, Switzerland.
| | - Matthias Peter
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8093, Zürich, Switzerland.
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27
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Karl LA, Peritore M, Galanti L, Pfander B. DNA Double Strand Break Repair and Its Control by Nucleosome Remodeling. Front Genet 2022; 12:821543. [PMID: 35096025 PMCID: PMC8790285 DOI: 10.3389/fgene.2021.821543] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 12/23/2021] [Indexed: 12/12/2022] Open
Abstract
DNA double strand breaks (DSBs) are repaired in eukaryotes by one of several cellular mechanisms. The decision-making process controlling DSB repair takes place at the step of DNA end resection, the nucleolytic processing of DNA ends, which generates single-stranded DNA overhangs. Dependent on the length of the overhang, a corresponding DSB repair mechanism is engaged. Interestingly, nucleosomes-the fundamental unit of chromatin-influence the activity of resection nucleases and nucleosome remodelers have emerged as key regulators of DSB repair. Nucleosome remodelers share a common enzymatic mechanism, but for global genome organization specific remodelers have been shown to exert distinct activities. Specifically, different remodelers have been found to slide and evict, position or edit nucleosomes. It is an open question whether the same remodelers exert the same function also in the context of DSBs. Here, we will review recent advances in our understanding of nucleosome remodelers at DSBs: to what extent nucleosome sliding, eviction, positioning and editing can be observed at DSBs and how these activities affect the DSB repair decision.
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Affiliation(s)
- Leonhard Andreas Karl
- Resarch Group DNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Martina Peritore
- Resarch Group DNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Lorenzo Galanti
- Resarch Group DNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Boris Pfander
- Resarch Group DNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, Martinsried, Germany
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28
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Nambiar TS, Baudrier L, Billon P, Ciccia A. CRISPR-based genome editing through the lens of DNA repair. Mol Cell 2022; 82:348-388. [PMID: 35063100 PMCID: PMC8887926 DOI: 10.1016/j.molcel.2021.12.026] [Citation(s) in RCA: 66] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 12/18/2021] [Accepted: 12/20/2021] [Indexed: 01/22/2023]
Abstract
Genome editing technologies operate by inducing site-specific DNA perturbations that are resolved by cellular DNA repair pathways. Products of genome editors include DNA breaks generated by CRISPR-associated nucleases, base modifications induced by base editors, DNA flaps created by prime editors, and integration intermediates formed by site-specific recombinases and transposases associated with CRISPR systems. Here, we discuss the cellular processes that repair CRISPR-generated DNA lesions and describe strategies to obtain desirable genomic changes through modulation of DNA repair pathways. Advances in our understanding of the DNA repair circuitry, in conjunction with the rapid development of innovative genome editing technologies, promise to greatly enhance our ability to improve food production, combat environmental pollution, develop cell-based therapies, and cure genetic and infectious diseases.
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Affiliation(s)
- Tarun S. Nambiar
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032
| | - Lou Baudrier
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive N. W., Calgary, Alberta T2N 4N1, Canada
| | - Pierre Billon
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive N. W., Calgary, Alberta T2N 4N1, Canada,Corresponding authors: ,
| | - Alberto Ciccia
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032,Lead Contact,Corresponding authors: ,
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29
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Wang X, Zhao J. Targeted Cancer Therapy Based on Acetylation and Deacetylation of Key Proteins Involved in Double-Strand Break Repair. Cancer Manag Res 2022; 14:259-271. [PMID: 35115826 PMCID: PMC8800007 DOI: 10.2147/cmar.s346052] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Accepted: 01/13/2022] [Indexed: 12/22/2022] Open
Abstract
DNA double-strand breaks (DSBs) play an important role in promoting genomic instability and cell death. The precise repair of DSBs is essential for maintaining genome integrity during cancer progression, and inducing genomic instability or blocking DNA repair is an important mechanism through which chemo/radiotherapies exert killing effects on cancer cells. The two main pathways that facilitate the repair of DSBs in cancer cells are homologous recombination (HR) and non-homologous end-joining (NHEJ). Accumulating data suggest that the acetylation and deacetylation of DSB repair proteins regulate the initiation and progression of the cellular response to DNA DSBs, which may further affect the chemosensitivity or radiosensitivity of cancer cells. Here, we focus on the role of acetylation/deacetylation in the regulation of ataxia-telangiectasia mutated, Rad51, and 53BP1 in the HR pathway, as well as the relevant roles of PARP1 and Ku70 in NHEJ. Notably, several histone deacetylase (HDAC) inhibitors targeting HR or NHEJ have been demonstrated to enhance chemo/radiosensitivity in preclinical studies. This review highlights the essential role of acetylation/deacetylation in the regulation of DSB repair proteins, suggesting that HDAC inhibitors targeting the HR or NHEJ pathways that downregulate DNA DSB repair genes may be worthwhile cancer therapeutic agents.
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Affiliation(s)
- Xiwen Wang
- Department of Thoracic Surgery, Shengjing Hospital of China Medical University, Shenyang, Liaoning, 110004, People’s Republic of China
| | - Jungang Zhao
- Department of Thoracic Surgery, Shengjing Hospital of China Medical University, Shenyang, Liaoning, 110004, People’s Republic of China
- Correspondence: Jungang Zhao, Department of Thoracic Surgery, Shengjing Hospital of China Medical University, Shenyang, Liaoning, 110004, People’s Republic of China, Tel/Fax +86 13889311066, Email
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30
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De Falco M, De Felice M. Take a Break to Repair: A Dip in the World of Double-Strand Break Repair Mechanisms Pointing the Gaze on Archaea. Int J Mol Sci 2021; 22:ijms222413296. [PMID: 34948099 PMCID: PMC8708640 DOI: 10.3390/ijms222413296] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 12/24/2022] Open
Abstract
All organisms have evolved many DNA repair pathways to counteract the different types of DNA damages. The detection of DNA damage leads to distinct cellular responses that bring about cell cycle arrest and the induction of DNA repair mechanisms. In particular, DNA double-strand breaks (DSBs) are extremely toxic for cell survival, that is why cells use specific mechanisms of DNA repair in order to maintain genome stability. The choice among the repair pathways is mainly linked to the cell cycle phases. Indeed, if it occurs in an inappropriate cellular context, it may cause genome rearrangements, giving rise to many types of human diseases, from developmental disorders to cancer. Here, we analyze the most recent remarks about the main pathways of DSB repair with the focus on homologous recombination. A thorough knowledge in DNA repair mechanisms is pivotal for identifying the most accurate treatments in human diseases.
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31
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Feng W, Smith CM, Simpson DA, Gupta GP. Targeting Non-homologous and Alternative End Joining Repair to Enhance Cancer Radiosensitivity. Semin Radiat Oncol 2021; 32:29-41. [PMID: 34861993 DOI: 10.1016/j.semradonc.2021.09.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Many cancer therapies, including radiotherapy, induce DSBs as the major driving mechanism for inducing cancer cell death. Thus, modulating DSB repair has immense potential for radiosensitization, although such interventions must be carefully designed to be tumor selective to ensure that normal tissue toxicities are not also increased. Here, we review mechanisms of error-prone DSB repair through a highly efficient process called end joining. There are two major pathways of end-joining repair: non-homologous end joining (NHEJ) and alternative end joining (a-EJ), both of which can be selectively upregulated in cancer and thus represent attractive therapeutic targets for radiosensitization. These EJ pathways each have therapeutically targetable pioneer factors - DNA-dependent protein kinase catalytic subunit (DNA-PKcs) for NHEJ and DNA Polymerase Theta (Pol θ) for a-EJ. We summarize the current status of therapeutic targeting of NHEJ and a-EJ to enhance the effects of radiotherapy - focusing on challenges that must be overcome and opportunities that require further exploration. By leveraging preclinical insights into mechanisms of altered DSB repair programs in cancer, selective radiosensitization through NHEJ and/or a-EJ targeting remains a highly attractive avenue for ongoing and future clinical investigation.
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Affiliation(s)
| | - Chelsea M Smith
- Lineberger Comprehensive Cancer Center; Pathobiology and Translational Science Graduate Program
| | | | - Gaorav P Gupta
- Lineberger Comprehensive Cancer Center; Pathobiology and Translational Science Graduate Program; Department of Radiation Oncology; Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC.
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32
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Abstract
DNA double-strand breaks (DSBs) are cytotoxic lesions that threaten genome integrity and cell viability. Typically, cells repair DSBs by either nonhomologous end joining (NHEJ) or homologous recombination (HR). The relative use of these two pathways depends on many factors, including cell cycle stage and the nature of the DNA ends. A critical determinant of repair pathway selection is the initiation of 5'→3' nucleolytic degradation of DNA ends, a process referred to as DNA end resection. End resection is essential to create single-stranded DNA overhangs, which serve as the substrate for the Rad51 recombinase to initiate HR and are refractory to NHEJ repair. Here, we review recent insights into the mechanisms of end resection, how it is regulated, and the pathological consequences of its dysregulation.
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Affiliation(s)
- Petr Cejka
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500 Bellinzona, Switzerland; .,Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH) Zürich, 8093 Zürich, Switzerland
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA; .,Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY 10032, USA
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33
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Giaccherini C, Gaillard P. Control of structure-specific endonucleases during homologous recombination in eukaryotes. Curr Opin Genet Dev 2021; 71:195-205. [PMID: 34624742 DOI: 10.1016/j.gde.2021.09.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/10/2021] [Accepted: 09/13/2021] [Indexed: 01/14/2023]
Abstract
Structure-Specific Endonucleases (SSE) are specialized DNA endonucleases that recognize and process DNA secondary structures without any strict dependency on the nucleotide sequence context. This enables them to act virtually anywhere in the genome and to make key contributions to the maintenance of genome stability by removing DNA structures that may stall essential cellular processes such as DNA replication, transcription, repair and chromosome segregation. During repair of double strand breaks by homologous recombination mechanisms, DNA secondary structures are formed and processed in a timely manner. Their homeostasis relies on the combined action of helicases, SSE and topoisomerases. In this review, we focus on how SSE contribute to DNA end resection, single-strand annealing and double-strand break repair, with an emphasis on how their action is fine-tuned in those processes.
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Affiliation(s)
- C Giaccherini
- Centre de Recherche en Cancérologie de Marseille, CRCM, Inserm, CNRS, Aix-Marseille Université, Institut Paoli-Calmettes, Marseille, France
| | - Phl Gaillard
- Centre de Recherche en Cancérologie de Marseille, CRCM, Inserm, CNRS, Aix-Marseille Université, Institut Paoli-Calmettes, Marseille, France.
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Yannuzzi I, Butler MA, Fernandez J, LaRocque JR. The Role of Drosophila CtIP in Homology-Directed Repair of DNA Double-Strand Breaks. Genes (Basel) 2021; 12:genes12091430. [PMID: 34573412 PMCID: PMC8468788 DOI: 10.3390/genes12091430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 09/05/2021] [Accepted: 09/14/2021] [Indexed: 11/16/2022] Open
Abstract
DNA double-strand breaks (DSBs) are a particularly genotoxic type of DNA damage that can result in chromosomal aberrations. Thus, proper repair of DSBs is essential to maintaining genome integrity. DSBs can be repaired by non-homologous end joining (NHEJ), where ends are processed before joining through ligation. Alternatively, DSBs can be repaired through homology-directed repair, either by homologous recombination (HR) or single-strand annealing (SSA). Both types of homology-directed repair are initiated by DNA end resection. In cultured human cells, the protein CtIP has been shown to play a role in DNA end resection through its interactions with CDK, BRCA1, DNA2, and the MRN complex. To elucidate the role of CtIP in a multicellular context, CRISPR/Cas9 genome editing was used to create a DmCtIPΔ allele in Drosophila melanogaster. Using the DSB repair reporter assay direct repeat of white (DR-white), a two-fold decrease in HR in DmCtIPΔ/Δ mutants was observed when compared to heterozygous controls. However, analysis of HR gene conversion tracts (GCTs) suggests DmCtIP plays a minimal role in determining GCT length. To assess the function of DmCtIP on both short (~550 bp) and long (~3.6 kb) end resection, modified homology-directed SSA repair assays were implemented, resulting in a two-fold decrease in SSA repair in both short and extensive end resection requirements in the DmCtIPΔ/Δ mutants compared to heterozygote controls. Through these analyses, we affirmed the importance of end resection on DSB repair pathway choice in multicellular systems, described the function of DmCtIP in short and extensive DNA end resection, and determined the impact of end resection on GCT length during HR.
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Affiliation(s)
- Ian Yannuzzi
- Biology Department, Georgetown College, Georgetown University, Washington, DC 20057, USA;
| | - Margaret A. Butler
- Georgetown University Medical Center, Department of Human Science, Georgetown University, Washington, DC 20057, USA; (M.A.B.); (J.F.)
| | - Joel Fernandez
- Georgetown University Medical Center, Department of Human Science, Georgetown University, Washington, DC 20057, USA; (M.A.B.); (J.F.)
| | - Jeannine R. LaRocque
- Georgetown University Medical Center, Department of Human Science, Georgetown University, Washington, DC 20057, USA; (M.A.B.); (J.F.)
- Correspondence:
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The chromatin remodeler Chd1 supports MRX and Exo1 functions in resection of DNA double-strand breaks. PLoS Genet 2021; 17:e1009807. [PMID: 34520455 PMCID: PMC8462745 DOI: 10.1371/journal.pgen.1009807] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 09/24/2021] [Accepted: 09/06/2021] [Indexed: 12/31/2022] Open
Abstract
Repair of DNA double-strand breaks (DSBs) by homologous recombination (HR) requires that the 5’-terminated DNA strands are resected to generate single-stranded DNA overhangs. This process is initiated by a short-range resection catalyzed by the MRX (Mre11-Rad50-Xrs2) complex, which is followed by a long-range step involving the nucleases Exo1 and Dna2. Here we show that the Saccharomyces cerevisiae ATP-dependent chromatin-remodeling protein Chd1 participates in both short- and long-range resection by promoting MRX and Exo1 association with the DSB ends. Furthermore, Chd1 reduces histone occupancy near the DSB ends and promotes DSB repair by HR. All these functions require Chd1 ATPase activity, supporting a role for Chd1 in the opening of chromatin at the DSB site to facilitate MRX and Exo1 processing activities. DNA double strand breaks (DSBs) are among the most severe types of damage occurring in the genome because their faulty repair can result in chromosome instability, commonly associated with carcinogenesis. Efficient and accurate repair of DSBs relies on several proteins required to process them. However, eukaryotic genomes are compacted into chromatin, which restricts the access to DNA of the enzymes devoted to repair DNA DSBs. To overcome this natural barrier, eukaryotes have evolved chromatin remodeling enzymes that use energy derived from ATP hydrolysis to modulate chromatin structure. Here, we examine the role in DSB repair of the ATP-dependent chromatin remodeler Chd1, which is frequently mutated in prostate cancer. We find that Chd1 is important to repair DNA DSBs by homologous recombination (HR) because it promotes the association with a damaged site of the MRX complex and Exo1, which are necessary to initiate HR. This Chd1 function requires its ATPase activity, suggesting that Chd1 increases the accessibility to chromatin to initiate repair of DNA lesions.
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Casari E, Gobbini E, Gnugnoli M, Mangiagalli M, Clerici M, Longhese MP. Dpb4 promotes resection of DNA double-strand breaks and checkpoint activation by acting in two different protein complexes. Nat Commun 2021; 12:4750. [PMID: 34362907 PMCID: PMC8346560 DOI: 10.1038/s41467-021-25090-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 07/20/2021] [Indexed: 12/24/2022] Open
Abstract
Budding yeast Dpb4 (POLE3/CHRAC17 in mammals) is a highly conserved histone fold protein that is shared by two protein complexes: the chromatin remodeler ISW2/hCHRAC and the DNA polymerase ε (Pol ε) holoenzyme. In Saccharomyces cerevisiae, Dpb4 forms histone-like dimers with Dls1 in the ISW2 complex and with Dpb3 in the Pol ε complex. Here, we show that Dpb4 plays two functions in sensing and processing DNA double-strand breaks (DSBs). Dpb4 promotes histone removal and DSB resection by interacting with Dls1 to facilitate the association of the Isw2 ATPase to DSBs. Furthermore, it promotes checkpoint activation by interacting with Dpb3 to facilitate the association of the checkpoint protein Rad9 to DSBs. Persistence of both Isw2 and Rad9 at DSBs is enhanced by the A62S mutation that is located in the Dpb4 histone fold domain and increases Dpb4 association at DSBs. Thus, Dpb4 exerts two distinct functions at DSBs depending on its interactors. The histone folding protein Dpb4 forms histone-like dimers within the ISW2 complex and the Pol ε complex in S. cerevisiae. Here the authors reveal insights into two distinct functions that Dpb4 exerts at DSBs depending on its interactors.
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Affiliation(s)
- Erika Casari
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano, Italy
| | - Elisa Gobbini
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano, Italy
| | - Marco Gnugnoli
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano, Italy
| | - Marco Mangiagalli
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano, Italy
| | - Michela Clerici
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano, Italy.
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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: 18] [Impact Index Per Article: 6.0] [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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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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Zahid S, Seif El Dahan M, Iehl F, Fernandez-Varela P, Le Du MH, Ropars V, Charbonnier JB. The Multifaceted Roles of Ku70/80. Int J Mol Sci 2021; 22:ijms22084134. [PMID: 33923616 PMCID: PMC8073936 DOI: 10.3390/ijms22084134] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 03/31/2021] [Accepted: 04/01/2021] [Indexed: 12/11/2022] Open
Abstract
DNA double-strand breaks (DSBs) are accidental lesions generated by various endogenous or exogenous stresses. DSBs are also genetically programmed events during the V(D)J recombination process, meiosis, or other genome rearrangements, and they are intentionally generated to kill cancer during chemo- and radiotherapy. Most DSBs are processed in mammalian cells by the classical nonhomologous end-joining (c-NHEJ) pathway. Understanding the molecular basis of c-NHEJ has major outcomes in several fields, including radiobiology, cancer therapy, immune disease, and genome editing. The heterodimer Ku70/80 (Ku) is a central actor of the c-NHEJ as it rapidly recognizes broken DNA ends in the cell and protects them from nuclease activity. It subsequently recruits many c-NHEJ effectors, including nucleases, polymerases, and the DNA ligase 4 complex. Beyond its DNA repair function, Ku is also involved in several other DNA metabolism processes. Here, we review the structural and functional data on the DNA and RNA recognition properties of Ku implicated in DNA repair and in telomeres maintenance.
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40
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A conserved Ctp1/CtIP C-terminal peptide stimulates Mre11 endonuclease activity. Proc Natl Acad Sci U S A 2021; 118:2016287118. [PMID: 33836577 DOI: 10.1073/pnas.2016287118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The Mre11-Rad50-Nbs1 complex (MRN) is important for repairing DNA double-strand breaks (DSBs) by homologous recombination (HR). The endonuclease activity of MRN is critical for resecting 5'-ended DNA strands at DSB ends, producing 3'-ended single-strand DNA, a prerequisite for HR. This endonuclease activity is stimulated by Ctp1, the Schizosaccharomyces pombe homolog of human CtIP. Here, with purified proteins, we show that Ctp1 phosphorylation stimulates MRN endonuclease activity by inducing the association of Ctp1 with Nbs1. The highly conserved extreme C terminus of Ctp1 is indispensable for MRN activation. Importantly, a polypeptide composed of the conserved 15 amino acids at the C terminus of Ctp1 (CT15) is sufficient to stimulate Mre11 endonuclease activity. Furthermore, the CT15 equivalent from CtIP can stimulate human MRE11 endonuclease activity, arguing for the generality of this stimulatory mechanism. Thus, we propose that Nbs1-mediated recruitment of CT15 plays a pivotal role in the activation of the Mre11 endonuclease by Ctp1/CtIP.
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41
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Marsella A, Gobbini E, Cassani C, Tisi R, Cannavo E, Reginato G, Cejka P, Longhese MP. Sae2 and Rif2 regulate MRX endonuclease activity at DNA double-strand breaks in opposite manners. Cell Rep 2021; 34:108906. [PMID: 33789097 PMCID: PMC8028314 DOI: 10.1016/j.celrep.2021.108906] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/29/2021] [Accepted: 03/04/2021] [Indexed: 11/17/2022] Open
Abstract
The Mre11-Rad50-Xrs2 (MRX) complex detects and processes DNA double-strand breaks (DSBs). Its DNA binding and processing activities are regulated by transitions between an ATP-bound state and a post-hydrolysis cutting state that is nucleolytically active. Mre11 endonuclease activity is stimulated by Sae2, whose lack increases MRX persistence at DSBs and checkpoint activation. Here we show that the Rif2 protein inhibits Mre11 endonuclease activity and is responsible for the increased MRX retention at DSBs in sae2Δ cells. We identify a Rad50 residue that is important for Rad50-Rif2 interaction and Rif2 inhibition of Mre11 nuclease. This residue is located near a Rad50 surface that binds Sae2 and is important in stabilizing the Mre11-Rad50 (MR) interaction in the cutting state. We propose that Sae2 stimulates Mre11 endonuclease activity by stabilizing a post-hydrolysis MR conformation that is competent for DNA cleavage, whereas Rif2 antagonizes this Sae2 function and stabilizes an endonuclease inactive MR conformation. Sae2 stimulates Mre11 endonuclease activity by stabilizing the MRX cutting state Rif2 inhibits Sae2-mediated stimulation of Mre11 endonuclease activity The rad50-N18S mutation escapes Rif2-mediated inhibition of Mre11 nuclease Rif2 stabilizes an endonuclease inactive MR conformation that persistently binds DSBs
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Affiliation(s)
- Antonio Marsella
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano 20126, Italy
| | - Elisa Gobbini
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano 20126, Italy
| | - Corinne Cassani
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano 20126, Italy
| | - Renata Tisi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano 20126, Italy
| | - Elda Cannavo
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona, Switzerland
| | - Giordano Reginato
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Petr Cejka
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano 20126, Italy.
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Jones CE, Forsburg SL. Monitoring Schizosaccharomyces pombe genome stress by visualizing end-binding protein Ku. Biol Open 2021; 10:bio.054346. [PMID: 33579693 PMCID: PMC7904001 DOI: 10.1242/bio.054346] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Studies of genome stability have exploited visualization of fluorescently tagged proteins in live cells to characterize DNA damage, checkpoint, and repair responses. In this report, we describe a new tool for fission yeast, a tagged version of the end-binding protein Pku70 which is part of the KU protein complex. We compare Pku70 localization to other markers upon treatment to various genotoxins, and identify a unique pattern of distribution. Pku70 provides a new tool to define and characterize DNA lesions and the repair response. Summary: The authors describe a fluorescently tagged Ku70 protein to monitor replication stress in live S. pombe cells.
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Affiliation(s)
- Chance E Jones
- 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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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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OsMre11 Is Required for Mitosis during Rice Growth and Development. Int J Mol Sci 2020; 22:ijms22010169. [PMID: 33375295 PMCID: PMC7795355 DOI: 10.3390/ijms22010169] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 12/22/2020] [Accepted: 12/22/2020] [Indexed: 11/16/2022] Open
Abstract
Meiotic recombination 11 (Mre11) is a relatively conserved nuclease in various species. Mre11 plays important roles in meiosis and DNA damage repair in yeast, humans and Arabidopsis, but little research has been done on mitotic DNA replication and repair in rice. Here, it was found that Mre11 was an extensively expressed gene among the various tissues and organs of rice, and loss-of-function of Mre11 resulted in severe defects of vegetative and reproductive growth, including dwarf plants, abnormally developed male and female gametes, and completely abortive seeds. The decreased number of cells in the apical meristem and the appearance of chromosomal fragments and bridges during the mitotic cell cycle in rice mre11 mutant roots revealed an essential role of OsMre11. Further research showed that DNA replication was suppressed, and a large number of DNA strand breaks occurred during the mitotic cell cycle of rice mre11 mutants. The expression of OsMre11 was up-regulated with the treatment of hydroxyurea and methyl methanesulfonate. Moreover, OsMre11 could form a complex with OsRad50 and OsNbs1, and they might function together in non-homologous end joining and homologous recombination repair pathways. These results indicated that OsMre11 plays vital roles in DNA replication and damage repair of the mitotic cell cycle, which ensure the development and fertility of rice by maintaining genome stability.
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45
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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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46
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Gobbini E, Casari E, Colombo CV, Bonetti D, Longhese MP. The 9-1-1 Complex Controls Mre11 Nuclease and Checkpoint Activation during Short-Range Resection of DNA Double-Strand Breaks. Cell Rep 2020; 33:108287. [DOI: 10.1016/j.celrep.2020.108287] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 09/08/2020] [Accepted: 09/28/2020] [Indexed: 12/17/2022] Open
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Britton S, Chanut P, Delteil C, Barboule N, Frit P, Calsou P. ATM antagonizes NHEJ proteins assembly and DNA-ends synapsis at single-ended DNA double strand breaks. Nucleic Acids Res 2020; 48:9710-9723. [PMID: 32890395 PMCID: PMC7515714 DOI: 10.1093/nar/gkaa723] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 07/29/2020] [Accepted: 08/21/2020] [Indexed: 12/15/2022] Open
Abstract
Two DNA repair pathways operate at DNA double strand breaks (DSBs): non-homologous end-joining (NHEJ), that requires two adjacent DNA ends for ligation, and homologous recombination (HR), that resects one DNA strand for invasion of a homologous duplex. Faithful repair of replicative single-ended DSBs (seDSBs) is mediated by HR, due to the lack of a second DNA end for end-joining. ATM stimulates resection at such breaks through multiple mechanisms including CtIP phosphorylation, which also promotes removal of the DNA-ends sensor and NHEJ protein Ku. Here, using a new method for imaging the recruitment of the Ku partner DNA-PKcs at DSBs, we uncover an unanticipated role of ATM in removing DNA-PKcs from seDSBs in human cells. Phosphorylation of DNA-PKcs on the ABCDE cluster is necessary not only for DNA-PKcs clearance but also for the subsequent MRE11/CtIP-dependent release of Ku from these breaks. We propose that at seDSBs, ATM activity is necessary for the release of both Ku and DNA-PKcs components of the NHEJ apparatus, and thereby prevents subsequent aberrant interactions between seDSBs accompanied by DNA-PKcs autophosphorylation and detrimental commitment to Lig4-dependent end-joining.
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Affiliation(s)
- Sébastien Britton
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
| | - Pauline Chanut
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
| | - Christine Delteil
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
| | - Nadia Barboule
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
| | - Philippe Frit
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
| | - Patrick Calsou
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
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48
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Lodovichi S, Cervelli T, Pellicioli A, Galli A. Inhibition of DNA Repair in Cancer Therapy: Toward a Multi-Target Approach. Int J Mol Sci 2020; 21:E6684. [PMID: 32932697 PMCID: PMC7554826 DOI: 10.3390/ijms21186684] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/04/2020] [Accepted: 09/08/2020] [Indexed: 12/19/2022] Open
Abstract
Alterations in DNA repair pathways are one of the main drivers of cancer insurgence. Nevertheless, cancer cells are more susceptible to DNA damage than normal cells and they rely on specific functional repair pathways to survive. Thanks to advances in genome sequencing, we now have a better idea of which genes are mutated in specific cancers and this prompted the development of inhibitors targeting DNA repair players involved in pathways essential for cancer cells survival. Currently, the pivotal concept is that combining the inhibition of mechanisms on which cancer cells viability depends is the most promising way to treat tumorigenesis. Numerous inhibitors have been developed and for many of them, efficacy has been demonstrated either alone or in combination with chemo or radiotherapy. In this review, we will analyze the principal pathways involved in cell cycle checkpoint and DNA repair focusing on how their alterations could predispose to cancer, then we will explore the inhibitors developed or in development specifically targeting different proteins involved in each pathway, underscoring the rationale behind their usage and how their combination and/or exploitation as adjuvants to classic therapies could help in patients clinical outcome.
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Affiliation(s)
- Samuele Lodovichi
- Bioscience Department, University of Milan, Via Celoria 26, 20131 Milan, Italy;
| | - Tiziana Cervelli
- Yeast Genetics and Genomics Group, Laboratory of Functional Genetics and Genomics, Institute of Clinical Physiology CNR, Via Moruzzi 1, 56125 Pisa, Italy;
| | - Achille Pellicioli
- Bioscience Department, University of Milan, Via Celoria 26, 20131 Milan, Italy;
| | - Alvaro Galli
- Yeast Genetics and Genomics Group, Laboratory of Functional Genetics and Genomics, Institute of Clinical Physiology CNR, Via Moruzzi 1, 56125 Pisa, Italy;
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49
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Regulation of the MLH1-MLH3 endonuclease in meiosis. Nature 2020; 586:618-622. [PMID: 32814904 DOI: 10.1038/s41586-020-2592-2] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 05/07/2020] [Indexed: 12/13/2022]
Abstract
During prophase of the first meiotic division, cells deliberately break their DNA1. These DNA breaks are repaired by homologous recombination, which facilitates proper chromosome segregation and enables the reciprocal exchange of DNA segments between homologous chromosomes2. A pathway that depends on the MLH1-MLH3 (MutLγ) nuclease has been implicated in the biased processing of meiotic recombination intermediates into crossovers by an unknown mechanism3-7. Here we have biochemically reconstituted key elements of this pro-crossover pathway. We show that human MSH4-MSH5 (MutSγ), which supports crossing over8, binds branched recombination intermediates and associates with MutLγ, stabilizing the ensemble at joint molecule structures and adjacent double-stranded DNA. MutSγ directly stimulates DNA cleavage by the MutLγ endonuclease. MutLγ activity is further stimulated by EXO1, but only when MutSγ is present. Replication factor C (RFC) and the proliferating cell nuclear antigen (PCNA) are additional components of the nuclease ensemble, thereby triggering crossing-over. Saccharomyces cerevisiae strains in which MutLγ cannot interact with PCNA present defects in forming crossovers. Finally, the MutLγ-MutSγ-EXO1-RFC-PCNA nuclease ensemble preferentially cleaves DNA with Holliday junctions, but shows no canonical resolvase activity. Instead, it probably processes meiotic recombination intermediates by nicking double-stranded DNA adjacent to the junction points9. As DNA nicking by MutLγ depends on its co-factors, the asymmetric distribution of MutSγ and RFC-PCNA on meiotic recombination intermediates may drive biased DNA cleavage. This mode of MutLγ nuclease activation might explain crossover-specific processing of Holliday junctions or their precursors in meiotic chromosomes4.
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50
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Li BZ, Putnam CD, Kolodner RD. Mechanisms underlying genome instability mediated by formation of foldback inversions in Saccharomyces cerevisiae. eLife 2020; 9:58223. [PMID: 32762846 PMCID: PMC7467729 DOI: 10.7554/elife.58223] [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: 04/24/2020] [Accepted: 08/04/2020] [Indexed: 01/09/2023] Open
Abstract
Foldback inversions, also called inverted duplications, have been observed in human genetic diseases and cancers. Here, we used a Saccharomyces cerevisiae genetic system that generates gross chromosomal rearrangements (GCRs) mediated by foldback inversions combined with whole-genome sequencing to study their formation. Foldback inversions were mediated by formation of single-stranded DNA hairpins. Two types of hairpins were identified: small-loop hairpins that were suppressed by MRE11, SAE2, SLX1, and YKU80 and large-loop hairpins that were suppressed by YEN1, TEL1, SWR1, and MRC1. Analysis of CRISPR/Cas9-induced double strand breaks (DSBs) revealed that long-stem hairpin-forming sequences could form foldback inversions when proximal or distal to the DSB, whereas short-stem hairpin-forming sequences formed foldback inversions when proximal to the DSB. Finally, we found that foldback inversion GCRs were stabilized by secondary rearrangements, mostly mediated by different homologous recombination mechanisms including single-strand annealing; however, POL32-dependent break-induced replication did not appear to be involved forming secondary rearrangements.
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Affiliation(s)
- Bin-Zhong Li
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, San Diego, United States
| | - Christopher D Putnam
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, San Diego, United States.,Departments of Medicine, University of California School of Medicine, San Diego, San Diego, United States
| | - Richard David Kolodner
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, San Diego, United States.,Cellular and Molecular Medicine, University of California School of Medicine, San Diego, San Diego, United States.,Moores-UCSD Cancer Center, University of California School of Medicine, San Diego, San Diego, United States.,Institute of Genomic Medicine, University of California School of Medicine, San Diego, San Diego, United States
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