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Papin C, Ibrahim A, Sabir JSM, Le Gras S, Stoll I, Albiheyri RS, Zari AT, Bahieldin A, Bellacosa A, Bronner C, Hamiche A. MBD4 loss results in global reactivation of promoters and retroelements with low methylated CpG density. J Exp Clin Cancer Res 2023; 42:301. [PMID: 37957685 PMCID: PMC10644448 DOI: 10.1186/s13046-023-02882-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: 05/17/2023] [Accepted: 11/02/2023] [Indexed: 11/15/2023] Open
Abstract
BACKGROUND Inherited defects in the base-excision repair gene MBD4 predispose individuals to adenomatous polyposis and colorectal cancer, which is characterized by an accumulation of C > T transitions resulting from spontaneous deamination of 5'-methylcytosine. METHODS Here, we have investigated the potential role of MBD4 in regulating DNA methylation levels using genome-wide transcriptome and methylome analyses. Additionally, we have elucidated its function through a series of in vitro experiments. RESULTS Here we show that the protein MBD4 is required for DNA methylation maintenance and G/T mismatch repair. Transcriptome and methylome analyses reveal a genome-wide hypomethylation of promoters, gene bodies and repetitive elements in the absence of MBD4 in vivo. Methylation mark loss is accompanied by a broad transcriptional derepression phenotype affecting promoters and retroelements with low methylated CpG density. MBD4 in vivo forms a complex with the mismatch repair proteins (MMR), which exhibits high bi-functional glycosylase/AP-lyase endonuclease specific activity towards methylated DNA substrates containing a G/T mismatch. Experiments using recombinant proteins reveal that the association of MBD4 with the MMR protein MLH1 is required for this activity. CONCLUSIONS Our data identify MBD4 as an enzyme specifically designed to repair deaminated 5-methylcytosines and underscores its critical role in safeguarding against methylation damage. Furthermore, it illustrates how MBD4 functions in normal and pathological conditions.
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Affiliation(s)
- Christophe Papin
- Institut de Génétique Et Biologie Moléculaire Et Cellulaire (IGBMC), UdS, CNRS, INSERM, Equipe Labélisée Ligue Contre Le Cancer, 1 Rue Laurent Fries, B.P. 10142, Illkirch, 67404, Cedex, France
| | - Abdulkhaleg Ibrahim
- Institut de Génétique Et Biologie Moléculaire Et Cellulaire (IGBMC), UdS, CNRS, INSERM, Equipe Labélisée Ligue Contre Le Cancer, 1 Rue Laurent Fries, B.P. 10142, Illkirch, 67404, Cedex, France
- National Research Centre for Tropical and Transboundary Diseases (NRCTTD), Alzentan, 99316, Libya
| | - Jamal S M Sabir
- Centre of Excellence in Bionanoscience, King Abdulaziz University, Jeddah, Saudi Arabia
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Stéphanie Le Gras
- Institut de Génétique Et Biologie Moléculaire Et Cellulaire (IGBMC), UdS, CNRS, INSERM, Equipe Labélisée Ligue Contre Le Cancer, 1 Rue Laurent Fries, B.P. 10142, Illkirch, 67404, Cedex, France
| | - Isabelle Stoll
- Institut de Génétique Et Biologie Moléculaire Et Cellulaire (IGBMC), UdS, CNRS, INSERM, Equipe Labélisée Ligue Contre Le Cancer, 1 Rue Laurent Fries, B.P. 10142, Illkirch, 67404, Cedex, France
| | - Raed S Albiheyri
- Centre of Excellence in Bionanoscience, King Abdulaziz University, Jeddah, Saudi Arabia
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ali T Zari
- Centre of Excellence in Bionanoscience, King Abdulaziz University, Jeddah, Saudi Arabia
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ahmed Bahieldin
- Centre of Excellence in Bionanoscience, King Abdulaziz University, Jeddah, Saudi Arabia
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Alfonso Bellacosa
- Cancer Biology Program, Cancer Epigenetics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Christian Bronner
- Institut de Génétique Et Biologie Moléculaire Et Cellulaire (IGBMC), UdS, CNRS, INSERM, Equipe Labélisée Ligue Contre Le Cancer, 1 Rue Laurent Fries, B.P. 10142, Illkirch, 67404, Cedex, France.
| | - Ali Hamiche
- Institut de Génétique Et Biologie Moléculaire Et Cellulaire (IGBMC), UdS, CNRS, INSERM, Equipe Labélisée Ligue Contre Le Cancer, 1 Rue Laurent Fries, B.P. 10142, Illkirch, 67404, Cedex, France.
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2
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Miller AK, Mao G, Knicely BG, Daniels HG, Rahal C, Putnam CD, Kolodner RD, Goellner EM. Rad5 and Its Human Homologs, HLTF and SHPRH, Are Novel Interactors of Mismatch Repair. Front Cell Dev Biol 2022; 10:843121. [PMID: 35784486 PMCID: PMC9243396 DOI: 10.3389/fcell.2022.843121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 05/16/2022] [Indexed: 12/02/2022] Open
Abstract
DNA mismatch repair (MMR) repairs replication errors, and MMR defects play a role in both inherited cancer predisposition syndromes and in sporadic cancers. MMR also recognizes mispairs caused by environmental and chemotherapeutic agents; however, in these cases mispair recognition leads to apoptosis and not repair. Although mutation avoidance by MMR is fairly well understood, MMR-associated proteins are still being identified. We performed a bioinformatic analysis that implicated Saccharomyces cerevisiae Rad5 as a candidate for interacting with the MMR proteins Msh2 and Mlh1. Rad5 is a DNA helicase and E3 ubiquitin ligase involved in post-replicative repair and damage tolerance. We confirmed both interactions and found that the Mlh1 interaction is mediated by a conserved Mlh1-interacting motif (MIP box). Despite this, we did not find a clear role for Rad5 in the canonical MMR mutation avoidance pathway. The interaction of Rad5 with Msh2 and Mlh1 is conserved in humans, although each of the Rad5 human homologs, HLTF and SHPRH, shared only one of the interactions: HLTF interacts with MSH2, and SHPRH interacts with MLH1. Moreover, depletion of SHPRH, but not HLTF, results in a mild increase in resistance to alkylating agents although not as strong as loss of MMR, suggesting gene duplication led to specialization of the MMR-protein associated roles of the human Rad5 homologs. These results provide insights into how MMR accessory factors involved in the MMR-dependent apoptotic response interact with the core MMR machinery and have important health implications into how human cells respond to environmental toxins, tumor development, and treatment choices of tumors with defects in Rad5 homologs.
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Affiliation(s)
- Anna K. Miller
- College of Medicine Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, United States
| | - Guogen Mao
- College of Medicine Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, United States
| | - Breanna G. Knicely
- College of Medicine Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, United States
| | - Hannah G. Daniels
- College of Medicine Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, United States
| | - Christine Rahal
- Ludiwg Institute for Cancer Research San Diego, San Diego, CA, United States
| | - Christopher D. Putnam
- Ludiwg Institute for Cancer Research San Diego, San Diego, CA, United States
- Department of Medicine, University of California San Diego, San Diego, CA, United States
| | - Richard D. Kolodner
- Ludiwg Institute for Cancer Research San Diego, San Diego, CA, United States
- Moores-UCSD Cancer Center, San Diego, CA, United States
- Institute of Genomic Medicine, San Diego, CA, United States
- Department of Cellular and Molecular Medicine, University of California San Diego, San Diego, CA, United States
| | - Eva M. Goellner
- College of Medicine Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, United States
- Markey Cancer Center, University of Kentucky, Lexington, KY, United States
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3
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Zhao X, Lu H, Usdin K. FAN1's protection against CGG repeat expansion requires its nuclease activity and is FANCD2-independent. Nucleic Acids Res 2021; 49:11643-11652. [PMID: 34718701 PMCID: PMC8599916 DOI: 10.1093/nar/gkab899] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 09/20/2021] [Accepted: 10/12/2021] [Indexed: 12/21/2022] Open
Abstract
The Repeat Expansion Diseases, a large group of human diseases that includes the fragile X-related disorders (FXDs) and Huntington's disease (HD), all result from expansion of a disease-specific microsatellite via a mechanism that is not fully understood. We have previously shown that mismatch repair (MMR) proteins are required for expansion in a mouse model of the FXDs, but that the FANCD2 and FANCI associated nuclease 1 (FAN1), a component of the Fanconi anemia (FA) DNA repair pathway, is protective. FAN1's nuclease activity has been reported to be dispensable for protection against expansion in an HD cell model. However, we show here that in a FXD mouse model a point mutation in the nuclease domain of FAN1 has the same effect on expansion as a null mutation. Furthermore, we show that FAN1 and another nuclease, EXO1, have an additive effect in protecting against MSH3-dependent expansions. Lastly, we show that the loss of FANCD2, a vital component of the Fanconi anemia DNA repair pathway, has no effect on expansions. Thus, FAN1 protects against MSH3-dependent expansions without diverting the expansion intermediates into the canonical FA pathway and this protection depends on FAN1 having an intact nuclease domain.
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Affiliation(s)
- Xiaonan Zhao
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Huiyan Lu
- Laboratory Animal Sciences section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Karen Usdin
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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4
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Rad27 and Exo1 function in different excision pathways for mismatch repair in Saccharomyces cerevisiae. Nat Commun 2021; 12:5568. [PMID: 34552065 PMCID: PMC8458276 DOI: 10.1038/s41467-021-25866-z] [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: 02/19/2021] [Accepted: 08/31/2021] [Indexed: 11/20/2022] Open
Abstract
Eukaryotic DNA Mismatch Repair (MMR) involves redundant exonuclease 1 (Exo1)-dependent and Exo1-independent pathways, of which the Exo1-independent pathway(s) is not well understood. The exo1Δ440-702 mutation, which deletes the MutS Homolog 2 (Msh2) and MutL Homolog 1 (Mlh1) interacting peptides (SHIP and MIP boxes, respectively), eliminates the Exo1 MMR functions but is not lethal in combination with rad27Δ mutations. Analyzing the effect of different combinations of the exo1Δ440-702 mutation, a rad27Δ mutation and the pms1-A99V mutation, which inactivates an Exo1-independent MMR pathway, demonstrated that each of these mutations inactivates a different MMR pathway. Furthermore, it was possible to reconstitute a Rad27- and Msh2-Msh6-dependent MMR reaction in vitro using a mispaired DNA substrate and other MMR proteins. Our results demonstrate Rad27 defines an Exo1-independent eukaryotic MMR pathway that is redundant with at least two other MMR pathways. Defects in DNA mismatch repair (MMR) have been linked to inherited and sporadic cancers. Here the authors demonstrate that the DNA repair protein Rad27 (human FEN1) functions in one of three redundant mispair excision pathways, where its flap endonuclease activity catalyzes mispair excision.
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5
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Goold R, Hamilton J, Menneteau T, Flower M, Bunting EL, Aldous SG, Porro A, Vicente JR, Allen ND, Wilkinson H, Bates GP, Sartori AA, Thalassinos K, Balmus G, Tabrizi SJ. FAN1 controls mismatch repair complex assembly via MLH1 retention to stabilize CAG repeat expansion in Huntington's disease. Cell Rep 2021; 36:109649. [PMID: 34469738 PMCID: PMC8424649 DOI: 10.1016/j.celrep.2021.109649] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 06/30/2021] [Accepted: 08/11/2021] [Indexed: 11/18/2022] Open
Abstract
CAG repeat expansion in the HTT gene drives Huntington's disease (HD) pathogenesis and is modulated by DNA damage repair pathways. In this context, the interaction between FAN1, a DNA-structure-specific nuclease, and MLH1, member of the DNA mismatch repair pathway (MMR), is not defined. Here, we identify a highly conserved SPYF motif at the N terminus of FAN1 that binds to MLH1. Our data support a model where FAN1 has two distinct functions to stabilize CAG repeats. On one hand, it binds MLH1 to restrict its recruitment by MSH3, thus inhibiting the assembly of a functional MMR complex that would otherwise promote CAG repeat expansion. On the other hand, it promotes accurate repair via its nuclease activity. These data highlight a potential avenue for HD therapeutics in attenuating somatic expansion.
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Affiliation(s)
- Robert Goold
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK; UK Dementia Research Institute, University College London, London WC1N 3BG, UK
| | - Joseph Hamilton
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK; UK Dementia Research Institute, University College London, London WC1N 3BG, UK
| | - Thomas Menneteau
- UK Dementia Research Institute, University College London, London WC1N 3BG, UK; Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London WC1E 6BT, UK
| | - Michael Flower
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK; UK Dementia Research Institute, University College London, London WC1N 3BG, UK
| | - Emma L Bunting
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Sarah G Aldous
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK; UK Dementia Research Institute, University College London, London WC1N 3BG, UK
| | - Antonio Porro
- Institute of Molecular Cancer Research, University of Zurich, Zurich 8057, Switzerland
| | - José R Vicente
- UK Dementia Research Institute, University of Cambridge, Cambridge CB2 0AH, UK
| | | | | | - Gillian P Bates
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK; UK Dementia Research Institute, University College London, London WC1N 3BG, UK
| | - Alessandro A Sartori
- Institute of Molecular Cancer Research, University of Zurich, Zurich 8057, Switzerland
| | - Konstantinos Thalassinos
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London WC1E 6BT, UK; Institute of Structural and Molecular Biology, Birkbeck College, University of London, London WC1E 7HX, UK
| | - Gabriel Balmus
- UK Dementia Research Institute, University of Cambridge, Cambridge CB2 0AH, UK; Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0AH, UK.
| | - Sarah J Tabrizi
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK; UK Dementia Research Institute, University College London, London WC1N 3BG, UK.
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6
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Porro A, Mohiuddin M, Zurfluh C, Spegg V, Dai J, Iehl F, Ropars V, Collotta G, Fishwick KM, Mozaffari NL, Guérois R, Jiricny J, Altmeyer M, Charbonnier JB, Pearson CE, Sartori AA. FAN1-MLH1 interaction affects repair of DNA interstrand cross-links and slipped-CAG/CTG repeats. SCIENCE ADVANCES 2021; 7:7/31/eabf7906. [PMID: 34330701 PMCID: PMC8324060 DOI: 10.1126/sciadv.abf7906] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 06/15/2021] [Indexed: 05/05/2023]
Abstract
FAN1, a DNA structure-specific nuclease, interacts with MLH1, but the repair pathways in which this complex acts are unknown. FAN1 processes DNA interstrand crosslinks (ICLs) and FAN1 variants are modifiers of the neurodegenerative Huntington's disease (HD), presumably by regulating HD-causing CAG repeat expansions. Here, we identify specific amino acid residues in two adjacent FAN1 motifs that are critical for MLH1 binding. Disruption of the FAN1-MLH1 interaction confers cellular hypersensitivity to ICL damage and defective repair of CAG/CTG slip-outs, intermediates of repeat expansion mutations. FAN1-S126 phosphorylation, which hinders FAN1-MLH1 association, is cell cycle-regulated by cyclin-dependent kinase activity and attenuated upon ICL induction. Our data highlight the FAN1-MLH1 complex as a phosphorylation-regulated determinant of ICL response and repeat stability, opening novel paths to modify cancer and neurodegeneration.
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Affiliation(s)
- Antonio Porro
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Mohiuddin Mohiuddin
- Program of Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Christina Zurfluh
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Vincent Spegg
- Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
| | - Jingqi Dai
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Florence Iehl
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Virginie Ropars
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Giulio Collotta
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Keri M Fishwick
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Nour L Mozaffari
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Raphaël Guérois
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Josef Jiricny
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Matthias Altmeyer
- Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
| | - Jean-Baptiste Charbonnier
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Christopher E Pearson
- Program of Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.
- Program of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Alessandro A Sartori
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland.
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Deshmukh AL, Porro A, Mohiuddin M, Lanni S, Panigrahi GB, Caron MC, Masson JY, Sartori AA, Pearson CE. FAN1, a DNA Repair Nuclease, as a Modifier of Repeat Expansion Disorders. J Huntingtons Dis 2021; 10:95-122. [PMID: 33579867 PMCID: PMC7990447 DOI: 10.3233/jhd-200448] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
FAN1 encodes a DNA repair nuclease. Genetic deficiencies, copy number variants, and single nucleotide variants of FAN1 have been linked to karyomegalic interstitial nephritis, 15q13.3 microdeletion/microduplication syndrome (autism, schizophrenia, and epilepsy), cancer, and most recently repeat expansion diseases. For seven CAG repeat expansion diseases (Huntington's disease (HD) and certain spinocerebellar ataxias), modification of age of onset is linked to variants of specific DNA repair proteins. FAN1 variants are the strongest modifiers. Non-coding disease-delaying FAN1 variants and coding disease-hastening variants (p.R507H and p.R377W) are known, where the former may lead to increased FAN1 levels and the latter have unknown effects upon FAN1 functions. Current thoughts are that ongoing repeat expansions in disease-vulnerable tissues, as individuals age, promote disease onset. Fan1 is required to suppress against high levels of ongoing somatic CAG and CGG repeat expansions in tissues of HD and FMR1 transgenic mice respectively, in addition to participating in DNA interstrand crosslink repair. FAN1 is also a modifier of autism, schizophrenia, and epilepsy. Coupled with the association of these diseases with repeat expansions, this suggests a common mechanism, by which FAN1 modifies repeat diseases. Yet how any of the FAN1 variants modify disease is unknown. Here, we review FAN1 variants, associated clinical effects, protein structure, and the enzyme's attributed functional roles. We highlight how variants may alter its activities in DNA damage response and/or repeat instability. A thorough awareness of the FAN1 gene and FAN1 protein functions will reveal if and how it may be targeted for clinical benefit.
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Affiliation(s)
- Amit L. Deshmukh
- Program of Genetics & Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada
| | - Antonio Porro
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Mohiuddin Mohiuddin
- Program of Genetics & Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada
| | - Stella Lanni
- Program of Genetics & Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada
| | - Gagan B. Panigrahi
- Program of Genetics & Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada
| | - Marie-Christine Caron
- Department of Molecular Biology, Medical Biochemistry and Pathology; Laval University Cancer Research Center, Québec City, Quebec, Canada
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Division, Québec City, Quebec, Canada
| | - Jean-Yves Masson
- Department of Molecular Biology, Medical Biochemistry and Pathology; Laval University Cancer Research Center, Québec City, Quebec, Canada
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Division, Québec City, Quebec, Canada
| | | | - Christopher E. Pearson
- Program of Genetics & Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada
- University of Toronto, Program of Molecular Genetics, Toronto, Ontario, Canada
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8
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Measurements of Protein-DNA Complexes Interactions by Isothermal Titration Calorimetry (ITC) and Microscale Thermophoresis (MST). Methods Mol Biol 2021; 2247:125-143. [PMID: 33301115 DOI: 10.1007/978-1-0716-1126-5_7] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Interactions between protein complexes and DNA are central regulators of the cell life. They control the activation and inactivation of a large set of nuclear processes including transcription, replication, recombination, repair, and chromosome structures. In the literature, protein-DNA interactions are characterized by highly complementary approaches including large-scale studies and analyses in cells. Biophysical approaches with purified materials help to evaluate if these interactions are direct or not. They provide quantitative information on the strength and specificity of the interactions between proteins or protein complexes and their DNA substrates. Isothermal titration calorimetry (ITC) and microscale thermophoresis (MST) are widely used and are complementary methods to characterize nucleo-protein complexes and quantitatively measure protein-DNA interactions. We present here protocols to analyze the interactions between a DNA repair complex, Ku70-Ku80 (Ku) (154 kDa), and DNA substrates. ITC is a label-free method performed with both partners in solution. It serves to determine the dissociation constant (Kd), the enthalpy (ΔH), and the stoichiometry N of an interaction. MST is used to measure the Kd between the protein or the DNA labeled with a fluorescent probe. We report the data obtained on Ku-DNA interactions with ITC and MST and discuss advantages and drawbacks of both the methods.
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9
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Exo1 recruits Cdc5 polo kinase to MutLγ to ensure efficient meiotic crossover formation. Proc Natl Acad Sci U S A 2020; 117:30577-30588. [PMID: 33199619 DOI: 10.1073/pnas.2013012117] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Crossovers generated during the repair of programmed meiotic double-strand breaks must be tightly regulated to promote accurate homolog segregation without deleterious outcomes, such as aneuploidy. The Mlh1-Mlh3 (MutLγ) endonuclease complex is critical for crossover resolution, which involves mechanistically unclear interplay between MutLγ and Exo1 and polo kinase Cdc5. Using budding yeast to gain temporal and genetic traction on crossover regulation, we find that MutLγ constitutively interacts with Exo1. Upon commitment to crossover repair, MutLγ-Exo1 associate with recombination intermediates, followed by direct Cdc5 recruitment that triggers MutLγ crossover activity. We propose that Exo1 serves as a central coordinator in this molecular interplay, providing a defined order of interaction that prevents deleterious, premature activation of crossovers. MutLγ associates at a lower frequency near centromeres, indicating that spatial regulation across chromosomal regions reduces risky crossover events. Our data elucidate the temporal and spatial control surrounding a constitutive, potentially harmful, nuclease. We also reveal a critical, noncatalytic role for Exo1, through noncanonical interaction with polo kinase. These mechanisms regulating meiotic crossovers may be conserved across species.
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10
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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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11
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Kumar M, Gouw M, Michael S, Sámano-Sánchez H, Pancsa R, Glavina J, Diakogianni A, Valverde JA, Bukirova D, Čalyševa J, Palopoli N, Davey NE, Chemes LB, Gibson TJ. ELM-the eukaryotic linear motif resource in 2020. Nucleic Acids Res 2020; 48:D296-D306. [PMID: 31680160 PMCID: PMC7145657 DOI: 10.1093/nar/gkz1030] [Citation(s) in RCA: 124] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 10/18/2019] [Accepted: 10/23/2019] [Indexed: 12/20/2022] Open
Abstract
The eukaryotic linear motif (ELM) resource is a repository of manually curated experimentally validated short linear motifs (SLiMs). Since the initial release almost 20 years ago, ELM has become an indispensable resource for the molecular biology community for investigating functional regions in many proteins. In this update, we have added 21 novel motif classes, made major revisions to 12 motif classes and added >400 new instances mostly focused on DNA damage, the cytoskeleton, SH2-binding phosphotyrosine motifs and motif mimicry by pathogenic bacterial effector proteins. The current release of the ELM database contains 289 motif classes and 3523 individual protein motif instances manually curated from 3467 scientific publications. ELM is available at: http://elm.eu.org.
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Affiliation(s)
- Manjeet Kumar
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Marc Gouw
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Sushama Michael
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Hugo Sámano-Sánchez
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany.,Collaboration for Joint PhD Degree between EMBL and Heidelberg University, Faculty of Biosciences
| | - Rita Pancsa
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest 1117, Hungary
| | - Juliana Glavina
- Instituto de Investigaciones Biotecnológicas (IIBio) and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de San Martín. Av. 25 de Mayo y Francia, CP1650, Buenos Aires, Argentina
| | - Athina Diakogianni
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Jesús Alvarado Valverde
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Dayana Bukirova
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany.,Nazarbayev University, Nur-Sultan 010000, Kazakhstan
| | - Jelena Čalyševa
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany.,Collaboration for Joint PhD Degree between EMBL and Heidelberg University, Faculty of Biosciences
| | - Nicolas Palopoli
- Department of Science and Technology, Universidad Nacional de Quilmes - CONICET, Bernal B1876BXD, Buenos Aires, Argentina
| | - Norman E Davey
- The Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Rd, Chelsea, London SW3 6JB, UK
| | - Lucía B Chemes
- Instituto de Investigaciones Biotecnológicas (IIBio) and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de San Martín. Av. 25 de Mayo y Francia, CP1650, Buenos Aires, Argentina
| | - Toby J Gibson
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany
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12
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Madru C, Henneke G, Raia P, Hugonneau-Beaufet I, Pehau-Arnaudet G, England P, Lindahl E, Delarue M, Carroni M, Sauguet L. Structural basis for the increased processivity of D-family DNA polymerases in complex with PCNA. Nat Commun 2020; 11:1591. [PMID: 32221299 PMCID: PMC7101311 DOI: 10.1038/s41467-020-15392-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 03/05/2020] [Indexed: 11/09/2022] Open
Abstract
Replicative DNA polymerases (DNAPs) have evolved the ability to copy the genome with high processivity and fidelity. In Eukarya and Archaea, the processivity of replicative DNAPs is greatly enhanced by its binding to the proliferative cell nuclear antigen (PCNA) that encircles the DNA. We determined the cryo-EM structure of the DNA-bound PolD–PCNA complex from Pyrococcus abyssi at 3.77 Å. Using an integrative structural biology approach — combining cryo-EM, X-ray crystallography, protein–protein interaction measurements, and activity assays — we describe the molecular basis for the interaction and cooperativity between a replicative DNAP and PCNA. PolD recruits PCNA via a complex mechanism, which requires two different PIP-boxes. We infer that the second PIP-box, which is shared with the eukaryotic Polα replicative DNAP, plays a dual role in binding either PCNA or primase, and could be a master switch between an initiation and a processive phase during replication. Replicative DNA polymerases (DNAPs) have evolved the ability to copy the genome with high processivity and fidelity. Here, the authors present a cryo-EM structure of the DNA-bound PolD–PCNA complex from Pyrococcus abyssi to reveal the molecular basis for the interaction and cooperativity between a replicative DNAP and PCNA.
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Affiliation(s)
- Clément Madru
- Unit of Structural Dynamics of Macromolecules, Institut Pasteur and CNRS UMR 3528, Paris, France
| | - Ghislaine Henneke
- CNRS, Ifremer, Université de Brest, Laboratoire de Microbiologie des Environnements Extrêmes, Plouzané, France
| | - Pierre Raia
- Unit of Structural Dynamics of Macromolecules, Institut Pasteur and CNRS UMR 3528, Paris, France.,Sorbonne Université, École Doctorale Complexité du Vivant (ED515), Paris, France
| | - Inès Hugonneau-Beaufet
- Unit of Structural Dynamics of Macromolecules, Institut Pasteur and CNRS UMR 3528, Paris, France
| | | | - Patrick England
- Molecular Biophysics Platform, C2RT, Institut Pasteur, CNRS UMR 3528, Paris, France
| | - Erik Lindahl
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm, Sweden.,Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Marc Delarue
- Unit of Structural Dynamics of Macromolecules, Institut Pasteur and CNRS UMR 3528, Paris, France
| | - Marta Carroni
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm, Sweden.
| | - Ludovic Sauguet
- Unit of Structural Dynamics of Macromolecules, Institut Pasteur and CNRS UMR 3528, Paris, France.
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13
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Pathania S, Randhawa V, Kumar M. Identifying potential entry inhibitors for emerging Nipah virus by molecular docking and chemical-protein interaction network. J Biomol Struct Dyn 2019; 38:5108-5125. [DOI: 10.1080/07391102.2019.1696705] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Shivalika Pathania
- Virology Unit and Bioinformatics Centre, Institute of Microbial Technology, Council of Scientific & Industrial Research, Chandigarh, India
| | - Vinay Randhawa
- Virology Unit and Bioinformatics Centre, Institute of Microbial Technology, Council of Scientific & Industrial Research, Chandigarh, India
| | - Manoj Kumar
- Virology Unit and Bioinformatics Centre, Institute of Microbial Technology, Council of Scientific & Industrial Research, Chandigarh, India
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14
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Houlleberghs H, Dekker M, Lusseveld J, Pieters W, van Ravesteyn T, Verhoef S, Hofstra RMW, Te Riele H. Three-step site-directed mutagenesis screen identifies pathogenic MLH1 variants associated with Lynch syndrome. J Med Genet 2019; 57:308-315. [PMID: 31784484 DOI: 10.1136/jmedgenet-2019-106520] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 10/12/2019] [Accepted: 10/16/2019] [Indexed: 12/30/2022]
Abstract
BACKGROUND Inactivating mutations in the MLH1 DNA mismatch repair (MMR) gene underlie 42% of Lynch syndrome (LS) cases. LS is a cancer predisposition causing early onset colorectal and endometrial cancer. Nonsense and frameshift alterations unambiguously cause LS. The phenotype of missense mutations that only alter a single amino acid is often unclear. These variants of uncertain significance (VUS) hinder LS diagnosis and family screening and therefore functional tests are urgently needed. We developed a functional test for MLH1 VUS termed 'oligonucleotide-directed mutation screening' (ODMS). METHODS The MLH1 variant was introduced by oligonucleotide-directed gene modification in mouse embryonic stem cells that were subsequently exposed to the guanine analogue 6-thioguanine to determine whether the variant abrogated MMR. RESUTS In a proof-of-principle analysis, we demonstrate that ODMS can distinguish pathogenic and non-pathogenic MLH1 variants with a sensitivity of >95% and a specificity of >91%. We subsequently applied the screen to 51 MLH1 VUS and identified 31 pathogenic variants. CONCLUSION ODMS is a reliable tool to identify pathogenic MLH1 variants. Implementation in clinical diagnostics will improve clinical care of patients with suspected LS and their relatives.
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Affiliation(s)
- Hellen Houlleberghs
- Division of Tumor Biology and Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Marleen Dekker
- Division of Tumor Biology and Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Jarnick Lusseveld
- Division of Tumor Biology and Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Wietske Pieters
- Division of Tumor Biology and Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Thomas van Ravesteyn
- Division of Tumor Biology and Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Senno Verhoef
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Robert M W Hofstra
- Department of Clinical Genetics, Erasmus MC, Erasmus University Rotterdam, Rotterdam, The Netherlands
| | - Hein Te Riele
- Division of Tumor Biology and Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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15
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Goellner EM. Chromatin remodeling and mismatch repair: Access and excision. DNA Repair (Amst) 2019; 85:102733. [PMID: 31698199 DOI: 10.1016/j.dnarep.2019.102733] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 09/06/2019] [Accepted: 10/09/2019] [Indexed: 01/03/2023]
Abstract
DNA mismatch repair (MMR) increases replication fidelity and genome stability by correcting DNA polymerase errors that remain after replication. Defects in MMR result in the accumulation of mutations and lead to human tumor development. Germline mutations in MMR cause the hereditary cancer syndrome, Lynch syndrome. After replication, DNA is reorganized into its chromatin structure and wrapped around histone octamers. DNA MMR is thought to be less efficient in recognizing and repairing mispairs packaged in chromatin, in which case MMR must either compete for access to naked DNA before histone deposition or actively move nucleosomes to access the mispair. This article reviews studies into the mechanistic and physical interactions between MMR and various chromatin-associated factors, including the histone deposition complex CAF1. Recent Xenopus and Saccharomyces cerevisiae studies describe a physical interaction between Msh2 and chromatin-remodeling ATPase Fun30/SMARCAD1, with potential mechanistic roles for SMARCAD1 in moving histones for both mispair access and excision tract elongation. The RSC complex, another histone remodeling complex, also potentially influences excision tract length. Deletion mutations of RSC2 point to mechanistic interactions with the MMR pathways. Together, these studies paint a picture of complex interactions between MMR and the chromatin environment that will require numerous additional genetic, biochemical, and cell biology experiments to fully understand. Understanding how these pathways interconnect is essential in fully understanding eukaryotic MMR and has numerous implications in human tumor formation and treatment.
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Affiliation(s)
- Eva M Goellner
- Department of Toxicology and Cancer Biology, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, 40536, USA.
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16
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Identification of Exo1-Msh2 interaction motifs in DNA mismatch repair and new Msh2-binding partners. Nat Struct Mol Biol 2018; 25:650-659. [PMID: 30061603 DOI: 10.1038/s41594-018-0092-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 06/14/2018] [Indexed: 02/07/2023]
Abstract
Eukaryotic DNA mismatch repair (MMR) involves both exonuclease 1 (Exo1)-dependent and Exo1-independent pathways. We found that the unstructured C-terminal domain of Saccharomyces cerevisiae Exo1 contains two MutS homolog 2 (Msh2)-interacting peptide (SHIP) boxes downstream from the MutL homolog 1 (Mlh1)-interacting peptide (MIP) box. These three sites were redundant in Exo1-dependent MMR in vivo and could be replaced by a fusion protein between an N-terminal fragment of Exo1 and Msh6. The SHIP-Msh2 interactions were eliminated by the msh2M470I mutation, and wild-type but not mutant SHIP peptides eliminated Exo1-dependent MMR in vitro. We identified two S. cerevisiae SHIP-box-containing proteins and three candidate human SHIP-box-containing proteins. One of these, Fun30, had a small role in Exo1-dependent MMR in vivo. The Remodeling of the Structure of Chromatin (Rsc) complex also functioned in both Exo1-dependent and Exo1-independent MMR in vivo. Our results identified two modes of Exo1 recruitment and a peptide module that mediates interactions between Msh2 and other proteins, and they support a model in which Exo1 functions in MMR by being tethered to the Msh2-Msh6 complex.
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17
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Helena JM, Joubert AM, Grobbelaar S, Nolte EM, Nel M, Pepper MS, Coetzee M, Mercier AE. Deoxyribonucleic Acid Damage and Repair: Capitalizing on Our Understanding of the Mechanisms of Maintaining Genomic Integrity for Therapeutic Purposes. Int J Mol Sci 2018; 19:E1148. [PMID: 29641431 PMCID: PMC5979424 DOI: 10.3390/ijms19041148] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 03/19/2018] [Accepted: 03/23/2018] [Indexed: 12/31/2022] Open
Abstract
Deoxyribonucleic acid (DNA) is the self-replicating hereditary material that provides a blueprint which, in collaboration with environmental influences, produces a structural and functional phenotype. As DNA coordinates and directs differentiation, growth, survival, and reproduction, it is responsible for life and the continuation of our species. Genome integrity requires the maintenance of DNA stability for the correct preservation of genetic information. This is facilitated by accurate DNA replication and precise DNA repair. DNA damage may arise from a wide range of both endogenous and exogenous sources but may be repaired through highly specific mechanisms. The most common mechanisms include mismatch, base excision, nucleotide excision, and double-strand DNA (dsDNA) break repair. Concurrent with regulation of the cell cycle, these mechanisms are precisely executed to ensure full restoration of damaged DNA. Failure or inaccuracy in DNA repair contributes to genome instability and loss of genetic information which may lead to mutations resulting in disease or loss of life. A detailed understanding of the mechanisms of DNA damage and its repair provides insight into disease pathogeneses and may facilitate diagnosis and the development of targeted therapies.
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Affiliation(s)
- Jolene Michelle Helena
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Anna Margaretha Joubert
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Simone Grobbelaar
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Elsie Magdalena Nolte
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Marcel Nel
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Michael Sean Pepper
- Institute for Cellular and Molecular Medicine, Department of Immunology, South African Medical Research Council (SAMRC) Extramural Unit for Stem Cell Research and Therapy, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Magdalena Coetzee
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Anne Elisabeth Mercier
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
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18
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Sgs1 Binding to Rad51 Stimulates Homology-Directed DNA Repair in Saccharomyces cerevisiae. Genetics 2017; 208:125-138. [PMID: 29162625 PMCID: PMC5753853 DOI: 10.1534/genetics.117.300545] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 11/16/2017] [Indexed: 12/23/2022] Open
Abstract
Accurate repair of DNA breaks is essential to maintain genome integrity and cellular fitness. Sgs1, the sole member of the RecQ family of DNA helicases in Saccharomyces cerevisiae, is important for both early and late stages of homology-dependent repair. Its large number of physical and genetic interactions with DNA recombination, repair, and replication factors has established Sgs1 as a key player in the maintenance of genome integrity. To determine the significance of Sgs1 binding to the strand-exchange factor Rad51, we have identified a single amino acid change at the C-terminal of the helicase core of Sgs1 that disrupts Rad51 binding. In contrast to an SGS1 deletion or a helicase-defective sgs1 allele, this new separation-of-function allele, sgs1-FD, does not cause DNA damage hypersensitivity or genome instability, but exhibits negative and positive genetic interactions with sae2Δ, mre11Δ, exo1Δ, srs2Δ, rrm3Δ, and pol32Δ that are distinct from those of known sgs1 mutants. Our findings suggest that the Sgs1-Rad51 interaction stimulates homologous recombination (HR). However, unlike sgs1 mutations, which impair the resection of DNA double-strand ends, negative genetic interactions of the sgs1-FD allele are not suppressed by YKU70 deletion. We propose that the Sgs1-Rad51 interaction stimulates HR by facilitating the formation of the presynaptic Rad51 filament, possibly by Sgs1 competing with single-stranded DNA for replication protein A binding during resection.
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19
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Jia P, Chastain M, Zou Y, Her C, Chai W. Human MLH1 suppresses the insertion of telomeric sequences at intra-chromosomal sites in telomerase-expressing cells. Nucleic Acids Res 2017; 45:1219-1232. [PMID: 28180301 PMCID: PMC5388398 DOI: 10.1093/nar/gkw1170] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 10/26/2016] [Accepted: 11/09/2016] [Indexed: 11/29/2022] Open
Abstract
Aberrant formation of interstitial telomeric sequences (ITSs) promotes genome instabilities. However, it is unclear how aberrant ITS formation is suppressed in human cells. Here, we report that MLH1, a key protein involved in mismatch repair (MMR), suppresses telomeric sequence insertion (TSI) at intra-chromosomal regions. The frequency of TSI can be elevated by double-strand break (DSB) inducer and abolished by ATM/ATR inhibition. Suppression of TSI requires MLH1 recruitment to DSBs, indicating that MLH1's role in DSB response/repair is important for suppressing TSI. Moreover, TSI requires telomerase activity but is independent of the functional status of p53 and Rb. Lastly, we show that TSI is associated with chromosome instabilities including chromosome loss, micronuclei formation and chromosome breakage that are further elevated by replication stress. Our studies uncover a novel link between MLH1, telomerase, telomere and genome stability.
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Affiliation(s)
- Pingping Jia
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA, USA
| | - Megan Chastain
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA, USA
| | - Ying Zou
- Cytogenetics Laboratory, Department of Pathology, the University of Maryland School of Medicine, Baltimore, MD, USA
| | - Chengtao Her
- School of Molecular Biosciences, Washington State University, Pullman, WA, USA
| | - Weihang Chai
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA, USA
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20
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Boehm EM, Washington MT. R.I.P. to the PIP: PCNA-binding motif no longer considered specific: PIP motifs and other related sequences are not distinct entities and can bind multiple proteins involved in genome maintenance. Bioessays 2016; 38:1117-1122. [PMID: 27539869 DOI: 10.1002/bies.201600116] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Many proteins responsible for genome maintenance interact with one another via short sequence motifs. The best known of these are PIP motifs, which mediate interactions with the replication protein PCNA. Others include RIR motifs, which bind the translesion synthesis protein Rev1, and MIP motifs, which bind the mismatch repair protein Mlh1. Although these motifs have similar consensus sequences, they have traditionally been viewed as separate motifs, each with their own target protein. In this article, we review several recent studies that challenge this view. Taken together, they imply that these different motifs are not distinct entities. Instead, there is a single, broader class of motifs, which we call "PIP-like" motifs, which have overlapping specificities and are capable of binding multiple target proteins. Given this, we must reassess the role of these motifs in forming the network of interacting proteins responsible for genome maintenance.
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Affiliation(s)
| | - M Todd Washington
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
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21
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Piekna-Przybylska D, Bambara RA, Balakrishnan L. Acetylation regulates DNA repair mechanisms in human cells. Cell Cycle 2016; 15:1506-17. [PMID: 27104361 DOI: 10.1080/15384101.2016.1176815] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The p300-mediated acetylation of enzymes involved in DNA repair and replication has been previously shown to stimulate or inhibit their activities in reconstituted systems. To explore the role of acetylation on DNA repair in cells we constructed plasmid substrates carrying inactivating damages in the EGFP reporter gene, which should be repaired in cells through DNA mismatch repair (MMR) or base excision repair (BER) mechanisms. We analyzed efficiency of repair within these plasmid substrates in cells exposed to deacetylase and acetyltransferase inhibitors, and also in cells deficient in p300 acetyltransferase. Our results indicate that protein acetylation improves DNA mismatch repair in MMR-proficient HeLa cells and also in MMR-deficient HCT116 cells. Moreover, results suggest that stimulated repair of mismatches in MMR-deficient HCT116 cells is done though a strand-displacement synthesis mechanism described previously for Okazaki fragments maturation and also for the EXOI-independent pathway of MMR. Loss of p300 reduced repair of mismatches in MMR-deficient cells, but did not have evident effects on BER mechanisms, including the long patch BER pathway. Hypoacetylation of the cells in the presence of acetyltransferase inhibitor, garcinol generally reduced efficiency of BER of 8-oxoG damage, indicating that some steps in the pathway are stimulated by acetylation.
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Affiliation(s)
- Dorota Piekna-Przybylska
- a Department of Microbiology and Immunology , School of Medicine and Dentistry, University of Rochester , Rochester , NY , USA
| | - Robert A Bambara
- a Department of Microbiology and Immunology , School of Medicine and Dentistry, University of Rochester , Rochester , NY , USA
| | - Lata Balakrishnan
- b Department of Biology , Indiana University-Purdue University Indianapolis , Indianapolis , IN , USA
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22
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Boehm EM, Powers KT, Kondratick CM, Spies M, Houtman JCD, Washington MT. The Proliferating Cell Nuclear Antigen (PCNA)-interacting Protein (PIP) Motif of DNA Polymerase η Mediates Its Interaction with the C-terminal Domain of Rev1. J Biol Chem 2016; 291:8735-44. [PMID: 26903512 DOI: 10.1074/jbc.m115.697938] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Indexed: 11/06/2022] Open
Abstract
Y-family DNA polymerases, such as polymerase η, polymerase ι, and polymerase κ, catalyze the bypass of DNA damage during translesion synthesis. These enzymes are recruited to sites of DNA damage by interacting with the essential replication accessory protein proliferating cell nuclear antigen (PCNA) and the scaffold protein Rev1. In most Y-family polymerases, these interactions are mediated by one or more conserved PCNA-interacting protein (PIP) motifs that bind in a hydrophobic pocket on the front side of PCNA as well as by conserved Rev1-interacting region (RIR) motifs that bind in a hydrophobic pocket on the C-terminal domain of Rev1. Yeast polymerase η, a prototypical translesion synthesis polymerase, binds both PCNA and Rev1. It possesses a single PIP motif but not an RIR motif. Here we show that the PIP motif of yeast polymerase η mediates its interactions both with PCNA and with Rev1. Moreover, the PIP motif of polymerase η binds in the hydrophobic pocket on the Rev1 C-terminal domain. We also show that the RIR motif of human polymerase κ and the PIP motif of yeast Msh6 bind both PCNA and Rev1. Overall, these findings demonstrate that PIP motifs and RIR motifs have overlapping specificities and can interact with both PCNA and Rev1 in structurally similar ways. These findings also suggest that PIP motifs are a more versatile protein interaction motif than previously believed.
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Affiliation(s)
| | | | | | | | - Jon C D Houtman
- Microbiology, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242
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23
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Samadder P, Aithal R, Belan O, Krejci L. Cancer TARGETases: DSB repair as a pharmacological target. Pharmacol Ther 2016; 161:111-131. [PMID: 26899499 DOI: 10.1016/j.pharmthera.2016.02.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cancer is a disease attributed to the accumulation of DNA damages due to incapacitation of DNA repair pathways resulting in genomic instability and a mutator phenotype. Among the DNA lesions, double stranded breaks (DSBs) are the most toxic forms of DNA damage which may arise as a result of extrinsic DNA damaging agents or intrinsic replication stress in fast proliferating cancer cells. Accurate repair of DSBs is therefore paramount to the cell survival, and several classes of proteins such as kinases, nucleases, helicases or core recombinational proteins have pre-defined jobs in precise execution of DSB repair pathways. On one hand, the proper functioning of these proteins ensures maintenance of genomic stability in normal cells, and on the other hand results in resistance to various drugs employed in cancer therapy and therefore presents a suitable opportunity for therapeutic targeting. Higher relapse and resistance in cancer patients due to non-specific, cytotoxic therapies is an alarming situation and it is becoming more evident to employ personalized treatment based on the genetic landscape of the cancer cells. For the success of personalized treatment, it is of immense importance to identify more suitable targetable proteins in DSB repair pathways and also to explore new synthetic lethal interactions with these pathways. Here we review the various alternative approaches to target the various protein classes termed as cancer TARGETases in DSB repair pathway to obtain more beneficial and selective therapy.
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Affiliation(s)
- Pounami Samadder
- National Centre for Biomolecular Research, Masaryk University, 62500 Brno, Czech Republic; International Clinical Research Center, Center for Biomolecular and Cellular Engineering, St. Anne's University Hospital in Brno, 60200 Brno, Czech Republic
| | - Rakesh Aithal
- National Centre for Biomolecular Research, Masaryk University, 62500 Brno, Czech Republic; Department of Biology, Masaryk University, 62500 Brno, Czech Republic
| | - Ondrej Belan
- Department of Biology, Masaryk University, 62500 Brno, Czech Republic
| | - Lumir Krejci
- National Centre for Biomolecular Research, Masaryk University, 62500 Brno, Czech Republic; International Clinical Research Center, Center for Biomolecular and Cellular Engineering, St. Anne's University Hospital in Brno, 60200 Brno, Czech Republic; Department of Biology, Masaryk University, 62500 Brno, Czech Republic.
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24
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Friedhoff P, Li P, Gotthardt J. Protein-protein interactions in DNA mismatch repair. DNA Repair (Amst) 2015; 38:50-57. [PMID: 26725162 DOI: 10.1016/j.dnarep.2015.11.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 11/11/2015] [Accepted: 11/30/2015] [Indexed: 11/25/2022]
Abstract
The principal DNA mismatch repair proteins MutS and MutL are versatile enzymes that couple DNA mismatch or damage recognition to other cellular processes. Besides interaction with their DNA substrates this involves transient interactions with other proteins which is triggered by the DNA mismatch or damage and controlled by conformational changes. Both MutS and MutL proteins have ATPase activity, which adds another level to control their activity and interactions with DNA substrates and other proteins. Here we focus on the protein-protein interactions, protein interaction sites and the different levels of structural knowledge about the protein complexes formed with MutS and MutL during the mismatch repair reaction.
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Affiliation(s)
- Peter Friedhoff
- Institute for Biochemistry FB 08, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany.
| | - Pingping Li
- Institute for Biochemistry FB 08, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany
| | - Julia Gotthardt
- Institute for Biochemistry FB 08, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany
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25
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Zhang F, Shi J, Bian C, Yu X. Poly(ADP-Ribose) Mediates the BRCA2-Dependent Early DNA Damage Response. Cell Rep 2015; 13:678-689. [PMID: 26489468 DOI: 10.1016/j.celrep.2015.09.040] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 07/26/2015] [Accepted: 09/14/2015] [Indexed: 01/01/2023] Open
Abstract
Breast cancer susceptibility gene 2 (BRCA2) plays a key role in DNA damage repair for maintaining genomic stability. Previous studies have shown that BRCA2 contains three tandem oligonucleotide/oligosaccharide binding folds (OB-folds) that are involved in DNA binding during DNA double-strand break repair. However, the molecular mechanism of BRCA2 in DNA damage repair remains elusive. Unexpectedly, we found that the OB-folds of BRCA2 recognize poly(ADP-ribose) (PAR) and mediate the fast recruitment of BRCA2 to DNA lesions, which is suppressed by PARP inhibitor treatment. Cancer-associated mutations in the OB-folds of BRCA2 disrupt the interaction with PAR and abolish the fast relocation of BRCA2 to DNA lesions. The quickly recruited BRCA2 is important for the early recruitment of exonuclease 1(EXO1) and is involved in DNA end resection, the first step of homologous recombination (HR). Thus, these findings uncover a molecular mechanism by which BRCA2 participates in DNA damage repair.
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Affiliation(s)
- Feng Zhang
- College of Life and Environment Sciences, Shanghai Normal University, Guilin Road 100, Shanghai 200234, China; Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA
| | - Jiazhong Shi
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA; Department of Cell Biology, the Third Military Medical University, Chongqing 400038, China
| | - Chunjing Bian
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA; Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91773, USA
| | - Xiaochun Yu
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA; Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91773, USA.
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26
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Zhang F, Shi J, Chen SH, Bian C, Yu X. The PIN domain of EXO1 recognizes poly(ADP-ribose) in DNA damage response. Nucleic Acids Res 2015; 43:10782-94. [PMID: 26400172 PMCID: PMC4678857 DOI: 10.1093/nar/gkv939] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Accepted: 09/08/2015] [Indexed: 11/14/2022] Open
Abstract
Following DNA double-strand breaks, poly(ADP-ribose) (PAR) is quickly and heavily synthesized to mediate fast and early recruitment of a number of DNA damage response factors to the sites of DNA lesions and facilitates DNA damage repair. Here, we found that EXO1, an exonuclease for DNA damage repair, is quickly recruited to the sites of DNA damage via PAR-binding. With further dissection of the functional domains of EXO1, we report that the PIN domain of EXO1 recognizes PAR both in vitro and in vivo and the interaction between the PIN domain and PAR is sufficient for the recruitment. We also found that the R93G variant of EXO1, generated by a single nucleotide polymorphism, abolishes the interaction and the early recruitment. Moreover, our study suggests that the PAR-mediated fast recruitment of EXO1 facilities early DNA end resection, the first step of homologous recombination repair. We observed that other PIN domains could also recognize DNA damage-induced PAR. Taken together, our study demonstrates a novel class of PAR-binding module that plays an important role in DNA damage response.
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Affiliation(s)
- Feng Zhang
- College of Life and Environment Sciences, Shanghai Normal University, Guilin Road 100, Shanghai 200234, China Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA
| | - Jiazhong Shi
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA Department of Cell Biology, the Third Military Medical University, Chongqing, 400038, China
| | - Shih-Hsun Chen
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91773, USA
| | - Chunjing Bian
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91773, USA
| | - Xiaochun Yu
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91773, USA
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27
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Abstract
DNA mismatch repair (MMR) acts to repair mispaired bases resulting from misincorporation errors during DNA replication and also recognizes mispaired bases in recombination (HR) intermediates. Exonuclease 1 (Exo1) is a 5' → 3' exonuclease that participates in a number of DNA repair pathways. Exo1 was identified as an exonuclease that participates in Saccharomyces cerevisiae and human MMR where it functions to excise the daughter strand after mispair recognition, and additionally Exo1 functions in end resection during HR. However, Exo1 is not absolutely required for end resection during HR in vivo. Similarly, while Exo1 is required in MMR reactions that have been reconstituted in vitro, genetics studies have shown that it is not absolutely required for MMR in vivo suggesting the existence of Exo1-independent and Exo1-dependent MMR subpathways. Here, we review what is known about the Exo1-independent and Exo1-dependent subpathways, including studies of mutations in MMR genes that specifically disrupt either subpathway.
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Affiliation(s)
- Eva M Goellner
- Ludwig Institute for Cancer Research, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA
| | - Christopher D Putnam
- Ludwig Institute for Cancer Research, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA; Departments of Medicine, University of California, San Diego School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA
| | - Richard D Kolodner
- Ludwig Institute for Cancer Research, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA; Departments of Cellular and Molecular Medicine, University of California, San Diego School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA; Moores - UCSD Cancer Center, University of California, San Diego School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA; Institute of Genomic Medicine, University of California, San Diego School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA.
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Guarné A, Charbonnier JB. Insights from a decade of biophysical studies on MutL: Roles in strand discrimination and mismatch removal. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 117:149-156. [PMID: 25701376 DOI: 10.1016/j.pbiomolbio.2015.02.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 01/31/2015] [Accepted: 02/09/2015] [Indexed: 11/18/2022]
Abstract
DNA mismatch repair (MMR) is a conserved pathway that safeguards genome integrity by correcting replication errors. The coordinated actions of two proteins (MutS and MutL) initiate the mismatch repair response and defects in the genes encoding for these proteins have been linked to sporadic and hereditary cancers. The basic steps to repair a mismatch include recognizing the mismatch, discriminating the newly synthesized from the parental strand, removing and re-synthesizing the erroneous strand. Although the DNA mismatch repair pathway has been extensively studied over the last four decades, the strand discrimination mechanism has remained elusive in most organisms. Work over the last decade has brought significant progress onto this step of the pathway, in turn ascribing new and critical roles to the MutL protein. In this review, we describe biochemical, biophysical and structural analyses that have clarified how MutL aids at discriminating the newly synthesized strand from its template and marking it for removal.
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Affiliation(s)
- Alba Guarné
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.
| | - Jean-Baptiste Charbonnier
- CEA, IBITECS, Laboratoire de Biologie Structurale et Radiobiologie, CE-Saclay, F-91191 Gif sur Yvette, France; CNRS, URA 2096, F-91191 Gif sur Yvette, France.
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29
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Shao H, Baitinger C, Soderblom EJ, Burdett V, Modrich P. Hydrolytic function of Exo1 in mammalian mismatch repair. Nucleic Acids Res 2014; 42:7104-12. [PMID: 24829455 PMCID: PMC4066806 DOI: 10.1093/nar/gku420] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Genetic and biochemical studies have previously implicated exonuclease 1 (Exo1) in yeast and mammalian mismatch repair, with results suggesting that function of the protein in the reaction depends on both its hydrolytic activity and its ability to interact with other components of the repair system. However, recent analysis of an Exo1-E109K knockin mouse has concluded that Exo1 function in mammalian mismatch repair is restricted to a structural role, a conclusion based on a prior report that N-terminal His-tagged Exo1-E109K is hydrolytically defective. Because Glu-109 is distant from the nuclease hydrolytic center, we have compared the activity of untagged full-length Exo1-E109K with that of wild type Exo1 and the hydrolytically defective active site mutant Exo1-D173A. We show that the activity of Exo1-E109K is comparable to that of wild type enzyme in a conventional exonuclease assay and that in contrast to a D173A active site mutant, Exo1-E109K is fully functional in mismatch-provoked excision and repair. We conclude that the catalytic function of Exo1 is required for its participation in mismatch repair. We also consider the other phenotypes of the Exo1-E109K mouse in the context of Exo1 hydrolytic function.
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Affiliation(s)
- Hongbing Shao
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Celia Baitinger
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - Erik J Soderblom
- Proteomics Core Facility, Duke University Medical Center, Durham, NC 27710, USA
| | - Vickers Burdett
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Paul Modrich
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
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30
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Bregenhorn S, Jiricny J. Biochemical characterization of a cancer-associated E109K missense variant of human exonuclease 1. Nucleic Acids Res 2014; 42:7096-103. [PMID: 24829445 PMCID: PMC4066805 DOI: 10.1093/nar/gku419] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mutations in the mismatch repair (MMR) genes MSH2, MSH6, MLH1 and PMS2 are associated with Lynch Syndrome (LS), a familial predisposition to early-onset cancer of the colon and other organs. Because not all LS families carry mutations in these four genes, the search for cancer-associated mutations was extended to genes encoding other members of the mismatch repairosome. This effort identified mutations in EXO1, which encodes the sole exonuclease implicated in MMR. One of these mutations, E109K, was reported to abrogate the catalytic activity of the enzyme, yet, in the crystal structure of the EXO1/DNA complex, this glutamate is far away from both DNA and the catalytic site of the enzyme. In an attempt to elucidate the reason underlying the putative loss of function of this variant, we expressed it in Escherichia coli, and tested its activity in a series of biochemical assays. We now report that, contrary to earlier reports, and unlike the catalytic site mutant D173A, the EXO1 E109K variant resembled the wild-type (wt) enzyme on all tested substrates. In the light of our findings, we attempt here to reinterpret the results of the phenotypic characterization of a knock-in mouse carrying the E109K mutation and cells derived from it.
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Affiliation(s)
- Stephanie Bregenhorn
- Institute of Molecular Cancer Research of the University of Zurich and the ETH Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Josef Jiricny
- Institute of Molecular Cancer Research of the University of Zurich and the ETH Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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31
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Zhang J, Yang R, Zhou D, Rudolph KL, Meng A, Ju Z. Exonuclease 1 is essential for maintaining genomic stability and the proliferative capacity of neural but not hematopoietic stem cells. Stem Cell Res 2014; 12:250-9. [DOI: 10.1016/j.scr.2013.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Revised: 09/26/2013] [Accepted: 11/01/2013] [Indexed: 12/29/2022] Open
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32
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Abstract
DNA repair mechanisms are critical for maintaining the integrity of genomic DNA, and their loss is associated with cancer predisposition syndromes. Studies in Saccharomyces cerevisiae have played a central role in elucidating the highly conserved mechanisms that promote eukaryotic genome stability. This review will focus on repair mechanisms that involve excision of a single strand from duplex DNA with the intact, complementary strand serving as a template to fill the resulting gap. These mechanisms are of two general types: those that remove damage from DNA and those that repair errors made during DNA synthesis. The major DNA-damage repair pathways are base excision repair and nucleotide excision repair, which, in the most simple terms, are distinguished by the extent of single-strand DNA removed together with the lesion. Mistakes made by DNA polymerases are corrected by the mismatch repair pathway, which also corrects mismatches generated when single strands of non-identical duplexes are exchanged during homologous recombination. In addition to the true repair pathways, the postreplication repair pathway allows lesions or structural aberrations that block replicative DNA polymerases to be tolerated. There are two bypass mechanisms: an error-free mechanism that involves a switch to an undamaged template for synthesis past the lesion and an error-prone mechanism that utilizes specialized translesion synthesis DNA polymerases to directly synthesize DNA across the lesion. A high level of functional redundancy exists among the pathways that deal with lesions, which minimizes the detrimental effects of endogenous and exogenous DNA damage.
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33
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Lenhart JS, Pillon MC, Guarné A, Simmons LA. Trapping and visualizing intermediate steps in the mismatch repair pathwayin vivo. Mol Microbiol 2013; 90:680-98. [DOI: 10.1111/mmi.12389] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2013] [Indexed: 01/08/2023]
Affiliation(s)
- Justin S. Lenhart
- Department of Molecular, Cellular, and Developmental Biology; University of Michigan; 830 North University Ave Ann Arbor MI 48109-1048 USA
| | - Monica C. Pillon
- Department of Biochemistry and Biomedical Sciences; McMaster University; 1280 Main Street West Hamilton Ontario L8S 4K1 Canada
| | - Alba Guarné
- Department of Biochemistry and Biomedical Sciences; McMaster University; 1280 Main Street West Hamilton Ontario L8S 4K1 Canada
| | - Lyle A. Simmons
- Department of Molecular, Cellular, and Developmental Biology; University of Michigan; 830 North University Ave Ann Arbor MI 48109-1048 USA
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34
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Perevoztchikova SA, Romanova EA, Oretskaya TS, Friedhoff P, Kubareva EA. Modern aspects of the structural and functional organization of the DNA mismatch repair system. Acta Naturae 2013; 5:17-34. [PMID: 24303200 PMCID: PMC3848065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This review is focused on the general aspects of the DNA mismatch repair (MMR) process. The key proteins of the DNA mismatch repair system are MutS and MutL. To date, their main structural and functional characteristics have been thoroughly studied. However, different opinions exist about the initial stages of the mismatch repair process with the participation of these proteins. This review aims to summarize the data on the relationship between the two MutS functions, ATPase and DNA-binding, and to systematize various models of coordination between the mismatch site and the strand discrimination site in DNA. To test these models, novel techniques for the trapping of short-living complexes that appear at different MMR stages are to be developed.
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Affiliation(s)
- S. A. Perevoztchikova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, 1, bld. 40, Moscow, Russia, 119991
| | - E. A. Romanova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, 1, bld. 40, Moscow, Russia, 119991
| | - T. S. Oretskaya
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, 1, bld. 40, Moscow, Russia, 119991
- Chemistry Department, Lomonosov Moscow State University, Leninskie Gory, 1, bld. 3, Moscow, Russia, 119991
| | - P. Friedhoff
- Institute of Biochemistry, FB 08, Justus Liebig University, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany
| | - E. A. Kubareva
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, 1, bld. 40, Moscow, Russia, 119991
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35
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Abstract
The mismatch repair (MMR) system detects non-Watson-Crick base pairs and strand misalignments arising during DNA replication and mediates their removal by catalyzing excision of the mispair-containing tract of nascent DNA and its error-free resynthesis. In this way, MMR improves the fidelity of replication by several orders of magnitude. It also addresses mispairs and strand misalignments arising during recombination and prevents synapses between nonidentical DNA sequences. Unsurprisingly, MMR malfunction brings about genomic instability that leads to cancer in mammals. But MMR proteins have recently been implicated also in other processes of DNA metabolism, such as DNA damage signaling, antibody diversification, and repair of interstrand cross-links and oxidative DNA damage, in which their functions remain to be elucidated. This article reviews the progress in our understanding of the mechanism of replication error repair made during the past decade.
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Affiliation(s)
- Josef Jiricny
- Institute of Molecular Cancer Research, University of Zurich and ETH Zurich, 8057 Zurich, Switzerland.
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36
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Structure of the MutLα C-terminal domain reveals how Mlh1 contributes to Pms1 endonuclease site. Nat Struct Mol Biol 2013; 20:461-8. [PMID: 23435383 DOI: 10.1038/nsmb.2511] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 01/04/2013] [Indexed: 01/30/2023]
Abstract
Mismatch-repair factors have a prominent role in surveying eukaryotic DNA-replication fidelity and in ensuring correct meiotic recombination. These functions depend on MutL-homolog heterodimers with Mlh1. In humans, MLH1 mutations underlie half of hereditary nonpolyposis colorectal cancers (HNPCCs). Here we report crystal structures of the MutLα (Mlh1-Pms1 heterodimer) C-terminal domain (CTD) from Saccharomyces cerevisiae, alone and in complex with fragments derived from Mlh1 partners. These structures reveal structural rearrangements and additional domains in MutLα as compared to the bacterial MutL counterparts and show that the strictly conserved C terminus of Mlh1 forms part of the Pms1 endonuclease site. The structures of the ternary complexes between MutLα(CTD) and Exo1 or Ntg2 fragments reveal the binding mode of the MIP-box motif shared by several Mlh1 partners. Finally, the structures provide a rationale for the deleterious impact of MLH1 mutations in HNPCCs.
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Exonuclease 1 (Exo1) is required for activating response to S(N)1 DNA methylating agents. DNA Repair (Amst) 2012; 11:951-64. [PMID: 23062884 DOI: 10.1016/j.dnarep.2012.09.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 09/08/2012] [Accepted: 09/11/2012] [Indexed: 11/23/2022]
Abstract
S(N)1 DNA methylating agents are genotoxic agents that methylate numerous nucleophilic centers within DNA including the O(6) position of guanine (O(6)meG). Methylation of this extracyclic oxygen forces mispairing with thymine during DNA replication. The mismatch repair (MMR) system recognizes these O(6)meG:T mispairs and is required to activate DNA damage response (DDR). Exonuclease I (EXO1) is a key component of MMR by resecting the damaged strand; however, whether EXO1 is required to activate MMR-dependent DDR remains unknown. Here we show that knockdown of the mouse ortholog (mExo1) in mouse embryonic fibroblasts (MEFs) results in decreased G2/M checkpoint response, limited effects on cell proliferation, and increased cell viability following exposure to the S(N)1 methylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), establishing a phenotype paralleling MMR deficiency. MNNG treatment induced formation of γ-H2AX foci with which EXO1 co-localized in MEFs, but mExo1-depleted MEFs displayed a significant diminishment of γ-H2AX foci formation. mExo1 depletion also reduced MSH2 association with DNA duplexes containing G:T mismatches in vitro, decreased MSH2 association with alkylated chromatin in vivo, and abrogated MNNG-induced MSH2/CHK1 interaction. To determine if nuclease activity is required to activate DDR we stably overexpressed a nuclease defective form of human EXO1 (hEXO1) in mExo1-depleted MEFs. These experiments indicated that expression of wildtype and catalytically null hEXO1 was able to restore normal response to MNNG. This study indicates that EXO1 is required to activate MMR-dependent DDR in response to S(N)1 methylating agents; however, this function of EXO1 is independent of its nucleolytic activity.
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38
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Andersen SD, Liberti SE, Lützen A, Drost M, Bernstein I, Nilbert M, Dominguez M, Nyström M, Hansen TVO, Christoffersen JW, Jäger AC, de Wind N, Nielsen FC, Tørring PM, Rasmussen LJ. Functional characterization ofMLH1missense variants identified in lynch syndrome patients. Hum Mutat 2012; 33:1647-55. [DOI: 10.1002/humu.22153] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 06/03/2012] [Indexed: 01/30/2023]
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39
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Andersen SD, Keijzers G, Rampakakis E, Engels K, Luhn P, El-Shemerly M, Nielsen FC, Du Y, May A, Bohr VA, Ferrari S, Zannis-Hadjopoulos M, Fu H, Rasmussen LJ. 14-3-3 checkpoint regulatory proteins interact specifically with DNA repair protein human exonuclease 1 (hEXO1) via a semi-conserved motif. DNA Repair (Amst) 2012; 11:267-77. [PMID: 22222486 DOI: 10.1016/j.dnarep.2011.11.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2011] [Revised: 11/06/2011] [Accepted: 11/30/2011] [Indexed: 12/14/2022]
Abstract
Human exonuclease 1 (hEXO1) acts directly in diverse DNA processing events, including replication, mismatch repair (MMR), and double strand break repair (DSBR), and it was also recently described to function as damage sensor and apoptosis inducer following DNA damage. In contrast, 14-3-3 proteins are regulatory phosphorserine/threonine binding proteins involved in the control of diverse cellular events, including cell cycle checkpoint and apoptosis signaling. hEXO1 is regulated by post-translation Ser/Thr phosphorylation in a yet not fully clarified manner, but evidently three phosphorylation sites are specifically induced by replication inhibition leading to protein ubiquitination and degradation. We demonstrate direct and robust interaction between hEXO1 and six of the seven 14-3-3 isoforms in vitro, suggestive of a novel protein interaction network between DNA repair and cell cycle control. Binding experiments reveal weak affinity of the more selective isoform 14-3-3σ but both 14-3-3 isoforms η and σ significantly stimulate hEXO1 activity, indicating that these regulatory proteins exert a common regulation mode on hEXO1. Results demonstrate that binding involves the phosphorable amino acid S746 in hEXO1 and most likely a second unidentified binding motif. 14-3-3 associations do not appear to directly influence hEXO1 in vitro nuclease activity or in vitro DNA replication initiation. Moreover, specific phosphorylation variants, including hEXO1 S746A, are efficiently imported to the nucleus; to associate with PCNA in distinct replication foci and respond to DNA double strand breaks (DSBs), indicating that 14-3-3 binding does not involve regulating the subcellular distribution of hEXO1. Altogether, these results suggest that association may be related to regulation of hEXO1 availability during the DNA damage response to plausibly prevent extensive DNA resection at the damage site, as supported by recent studies.
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40
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The functions of MutL in mismatch repair: the power of multitasking. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 110:41-70. [PMID: 22749142 DOI: 10.1016/b978-0-12-387665-2.00003-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
DNA mismatch repair enhances genomic stability by correcting errors that have escaped polymerase proofreading. One of the critical steps in DNA mismatch repair is discriminating the new from the parental DNA strand as only the former needs repair. In Escherichia coli, the latent endonuclease MutH carries out this function. However, most prokaryotes and all eukaryotes lack a mutH gene. MutL is a key component of this system that mediates protein-protein interactions during mismatch recognition, strand discrimination, and strand removal. Hence, it had long been thought that the primary function of MutL was coordinating sequential mismatch repair steps. However, recent studies have revealed that most MutL homologs from organisms lacking MutH encode a conserved metal-binding motif associated with a weak endonuclease activity. As MutL homologs bearing this activity are found only in organisms relying on MutH-independent DNA mismatch repair, this finding unveils yet another crucial function of the MutL protein at the strand discrimination step. In this chapter, we review recent functional and structural work aimed at characterizing the multiple functions of MutL and discuss how the endonuclease activity of MutL is regulated by other repair factors.
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41
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Swartzlander DB, Bauer NC, Corbett AH, Doetsch PW. Regulation of base excision repair in eukaryotes by dynamic localization strategies. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 110:93-121. [PMID: 22749144 DOI: 10.1016/b978-0-12-387665-2.00005-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
This chapter discusses base excision repair (BER) and the known mechanisms defined thus far regulating BER in eukaryotes. Unlike the situation with nucleotide excision repair and double-strand break repair, little is known about how BER is regulated to allow for efficient and accurate repair of many types of DNA base damage in both nuclear and mitochondrial genomes. Regulation of BER has been proposed to occur at multiple, different levels including transcription, posttranslational modification, protein-protein interactions, and protein localization; however, none of these regulatory mechanisms characterized thus far affect a large spectrum of BER proteins. This chapter discusses a recently discovered mode of BER regulation defined in budding yeast cells that involves mobilization of DNA repair proteins to DNA-containing organelles in response to genotoxic stress.
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Affiliation(s)
- Daniel B Swartzlander
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
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Abstract
The RecQ helicases are conserved from bacteria to humans and play a critical role in genome stability. In humans, loss of RecQ gene function is associated with cancer predisposition and/or premature aging. Recent experiments have shown that the RecQ helicases function during distinct steps during DNA repair; DNA end resection, displacement-loop (D-loop) processing, branch migration, and resolution of double Holliday junctions (dHJs). RecQ function in these different processing steps has important implications for its role in repair of double-strand breaks (DSBs) that occur during DNA replication and meiosis, as well as at specific genomic loci such as telomeres.
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Affiliation(s)
- Kara A Bernstein
- Columbia University Medical Center, Department of Genetics & Development, New York, New York 10032, USA.
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Zakharyevich K, Ma Y, Tang S, Hwang PYH, Boiteux S, Hunter N. Temporally and biochemically distinct activities of Exo1 during meiosis: double-strand break resection and resolution of double Holliday junctions. Mol Cell 2010; 40:1001-15. [PMID: 21172664 PMCID: PMC3061447 DOI: 10.1016/j.molcel.2010.11.032] [Citation(s) in RCA: 178] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 09/21/2010] [Accepted: 10/21/2010] [Indexed: 01/09/2023]
Abstract
The Rad2/XPG family nuclease, Exo1, functions in a variety of DNA repair pathways. During meiosis, Exo1 promotes crossover recombination and thereby facilitates chromosome segregation at the first division. Meiotic recombination is initiated by programmed DNA double-strand breaks (DSBs). Nucleolytic resection of DSBs generates long 3' single-strand tails that undergo strand exchange with a homologous chromosome to form joint molecule (JM) intermediates. We show that meiotic DSB resection is dramatically reduced in exo1Δ mutants and test the idea that Exo1-catalyzed resection promotes crossing over by facilitating formation of crossover-specific JMs called double Holliday junctions (dHJs). Contrary to this idea, dHJs form at wild-type levels in exo1Δ mutants, implying that Exo1 has a second function that promotes resolution of dHJs into crossovers. Surprisingly, the dHJ resolution function of Exo1 is independent of its nuclease activities but requires interaction with the putative endonuclease complex, Mlh1-Mlh3. Thus, the DSB resection and procrossover functions of Exo1 during meiosis involve temporally and biochemically distinct activities.
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Affiliation(s)
- Kseniya Zakharyevich
- Howard Hughes Medical Institute and the Departments of Microbiology, Molecular & Cellular Biology and Cell Biology & Human Anatomy, University of California Davis, One Shields Ave., Davis, CA 95616, USA
| | - Yunmei Ma
- Howard Hughes Medical Institute and the Departments of Microbiology, Molecular & Cellular Biology and Cell Biology & Human Anatomy, University of California Davis, One Shields Ave., Davis, CA 95616, USA
| | - Shangming Tang
- Howard Hughes Medical Institute and the Departments of Microbiology, Molecular & Cellular Biology and Cell Biology & Human Anatomy, University of California Davis, One Shields Ave., Davis, CA 95616, USA
| | - Patty Yi-Hwa Hwang
- Howard Hughes Medical Institute and the Departments of Microbiology, Molecular & Cellular Biology and Cell Biology & Human Anatomy, University of California Davis, One Shields Ave., Davis, CA 95616, USA
| | - Serge Boiteux
- CEA SDV/IRCM UMR217 CNRS Radiobiologie Moléculaire et Cellulaire, CEA Fontenay aux Roses, France
| | - Neil Hunter
- Howard Hughes Medical Institute and the Departments of Microbiology, Molecular & Cellular Biology and Cell Biology & Human Anatomy, University of California Davis, One Shields Ave., Davis, CA 95616, USA
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Amin AD, Chaix ABH, Mason RP, Badge RM, Borts RH. The roles of the Saccharomyces cerevisiae RecQ helicase SGS1 in meiotic genome surveillance. PLoS One 2010; 5:e15380. [PMID: 21085703 PMCID: PMC2976770 DOI: 10.1371/journal.pone.0015380] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Accepted: 09/01/2010] [Indexed: 11/24/2022] Open
Abstract
Background The Saccharomyces cerevisiae RecQ helicase Sgs1 is essential for mitotic and meiotic genome stability. The stage at which Sgs1 acts during meiosis is subject to debate. Cytological experiments showed that a deletion of SGS1 leads to an increase in synapsis initiation complexes and axial associations leading to the proposal that it has an early role in unwinding surplus strand invasion events. Physical studies of recombination intermediates implicate it in the dissolution of double Holliday junctions between sister chromatids. Methodology/Principal Findings In this work, we observed an increase in meiotic recombination between diverged sequences (homeologous recombination) and an increase in unequal sister chromatid events when SGS1 is deleted. The first of these observations is most consistent with an early role of Sgs1 in unwinding inappropriate strand invasion events while the second is consistent with unwinding or dissolution of recombination intermediates in an Mlh1- and Top3-dependent manner. We also provide data that suggest that Sgs1 is involved in the rejection of ‘second strand capture’ when sequence divergence is present. Finally, we have identified a novel class of tetrads where non-sister spores (pairs of spores where each contains a centromere marker from a different parent) are inviable. We propose a model for this unusual pattern of viability based on the inability of sgs1 mutants to untangle intertwined chromosomes. Our data suggest that this role of Sgs1 is not dependent on its interaction with Top3. We propose that in the absence of SGS1 chromosomes may sometimes remain entangled at the end of pre-meiotic replication. This, combined with reciprocal crossing over, could lead to physical destruction of the recombined and entangled chromosomes. We hypothesise that Sgs1, acting in concert with the topoisomerase Top2, resolves these structures. Conclusions This work provides evidence that Sgs1 interacts with various partner proteins to maintain genome stability throughout meiosis.
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Affiliation(s)
- Amit Dipak Amin
- Department of Genetics, University of Leicester, Leicester, United Kingdom
| | | | - Robert P. Mason
- Department of Genetics, University of Leicester, Leicester, United Kingdom
| | - Richard M. Badge
- Department of Genetics, University of Leicester, Leicester, United Kingdom
| | - Rhona H. Borts
- Department of Genetics, University of Leicester, Leicester, United Kingdom
- * E-mail:
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Keelagher RE, Cotton VE, Goldman ASH, Borts RH. Separable roles for Exonuclease I in meiotic DNA double-strand break repair. DNA Repair (Amst) 2010; 10:126-37. [PMID: 21044871 DOI: 10.1016/j.dnarep.2010.09.024] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2010] [Revised: 09/29/2010] [Accepted: 09/30/2010] [Indexed: 11/18/2022]
Abstract
Exo1 is a member of the Rad2 protein family and possesses both 5'-3' exonuclease and 5' flap endonuclease activities. In addition to performing a variety of functions during mitotic growth, Exo1 is also important for the production of crossovers during meiosis. However, its precise molecular role has remained ambiguous and several models have been proposed to account for the crossover deficit observed in its absence. Here, we present physical evidence that the nuclease activity of Exo1 is essential for normal 5'-3' resection at the Spo11-dependent HIS4 hotspot in otherwise wild-type cells. This same activity was also required for normal levels of gene conversion at the locus. However, gene conversions were frequently observed at a distance beyond that at which resection was readily detectable arguing that it is not the extent of the initial DNA end resection that limits heteroduplex formation. In addition to these nuclease-dependent functions, we found that an exo1-D173A mutant defective in nuclease activity is able to maintain crossing-over at wild-type levels in a number of genetic intervals, suggesting that Exo1 also plays a nuclease-independent role in crossover promotion.
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Liberti SE, Andersen SD, Wang J, May A, Miron S, Perderiset M, Keijzers G, Nielsen FC, Charbonnier JB, Bohr VA, Rasmussen LJ. Bi-directional routing of DNA mismatch repair protein human exonuclease 1 to replication foci and DNA double strand breaks. DNA Repair (Amst) 2010; 10:73-86. [PMID: 20970388 DOI: 10.1016/j.dnarep.2010.09.023] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2010] [Revised: 09/26/2010] [Accepted: 09/28/2010] [Indexed: 01/23/2023]
Abstract
Human exonuclease 1 (hEXO1) is implicated in DNA metabolism, including replication, recombination and repair, substantiated by its interactions with PCNA, DNA helicases BLM and WRN, and several DNA mismatch repair (MMR) proteins. We investigated the sub-nuclear localization of hEXO1 during S-phase progression and in response to laser-induced DNA double strand breaks (DSBs). We show that hEXO1 and PCNA co-localize in replication foci. This apparent interaction is sustained throughout S-phase. We also demonstrate that hEXO1 is rapidly recruited to DNA DSBs. We have identified a PCNA interacting protein (PIP-box) region on hEXO1 located in its COOH-terminal ((788)QIKLNELW(795)). This motif is essential for PCNA binding and co-localization during S-phase. Recruitment of hEXO1 to DNA DSB sites is dependent on the MMR protein hMLH1. We show that two distinct hMLH1 interaction regions of hEXO1 (residues 390-490 and 787-846) are required to direct the protein to the DNA damage site. Our results reveal that protein domains in hEXO1 in conjunction with specific protein interactions control bi-directional routing of hEXO1 between on-going DNA replication and repair processes in living cells.
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Affiliation(s)
- Sascha E Liberti
- Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
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47
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Polosina YY, Cupples CG. Wot the 'L-Does MutL do? Mutat Res 2010; 705:228-38. [PMID: 20667509 DOI: 10.1016/j.mrrev.2010.07.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 07/13/2010] [Accepted: 07/14/2010] [Indexed: 11/26/2022]
Abstract
In model DNA, A pairs with T, and C with G. However, in vivo, the complementarity of the DNA strands may be disrupted by errors in DNA replication, biochemical modification of bases and recombination. In prokaryotic organisms, mispaired bases are recognized by MutS homologs which, together with MutL homologs, initiate mismatch repair. These same proteins also participate in base excision repair and nucleotide excision repair. In eukaryotes they regulate not just DNA repair but also meiotic recombination, cell-cycle delay and/or apoptosis in response to DNA damage, and hypermutation in immunoglobulin genes. Significantly, the same DNA mismatches that trigger repair in some circumstances trigger non-repair pathways in others. In this review, we argue that mismatch recognition by the MutS proteins is linked to these disparate biological outcomes through regulated interaction of MutL proteins with a wide variety of effector proteins.
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Affiliation(s)
- Yaroslava Y Polosina
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 3055, STN CSC, Victoria, BC, Canada.
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Arana ME, Holmes SF, Fortune JM, Moon AF, Pedersen LC, Kunkel TA. Functional residues on the surface of the N-terminal domain of yeast Pms1. DNA Repair (Amst) 2010; 9:448-57. [PMID: 20138591 DOI: 10.1016/j.dnarep.2010.01.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2009] [Revised: 01/07/2010] [Accepted: 01/07/2010] [Indexed: 01/21/2023]
Abstract
Saccharomyces cerevisiae MutLalpha is a heterodimer of Mlh1 and Pms1 that participates in DNA mismatch repair (MMR). Both proteins have weakly conserved C-terminal regions (CTDs), with the CTD of Pms1 harboring an essential endonuclease activity. These proteins also have conserved N-terminal domains (NTDs) that bind and hydrolyze ATP and bind to DNA. To better understand Pms1 functions and potential interactions with DNA and/or other proteins, we solved the 2.5A crystal structure of yeast Pms1 (yPms1) NTD. The structure is similar to the homologous NTDs of Escherichia coli MutL and human PMS2, including the site involved in ATP binding and hydrolysis. The structure reveals a number of conserved, positively charged surface residues that do not interact with other residues in the NTD and are therefore candidates for interactions with DNA, with the CTD and/or with other proteins. When these were replaced with glutamate, several replacements resulted in yeast strains with elevated mutation rates. Two replacements also resulted in NTDs with decreased DNA binding affinity in vitro, suggesting that these residues contribute to DNA binding that is important for mismatch repair. Elevated mutation rates also resulted from surface residue replacements that did not affect DNA binding, suggesting that these conserved residues serve other functions, possibly involving interactions with other MMR proteins.
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Affiliation(s)
- Mercedes E Arana
- Laboratory of Molecular Genetics, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, United States
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Iyer RR, Pluciennik A, Genschel J, Tsai MS, Beese LS, Modrich P. MutLalpha and proliferating cell nuclear antigen share binding sites on MutSbeta. J Biol Chem 2010; 285:11730-9. [PMID: 20154325 PMCID: PMC2857047 DOI: 10.1074/jbc.m110.104125] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
MutSbeta (MSH2-MSH3) mediates repair of insertion-deletion heterologies but also triggers triplet repeat expansions that cause neurological diseases. Like other DNA metabolic activities, MutSbeta interacts with proliferating cell nuclear antigen (PCNA) via a conserved motif (QXX(L/I)XXFF). We demonstrate that MutSbeta-PCNA complex formation occurs with an affinity of approximately 0.1 microM and a preferred stoichiometry of 1:1. However, up to 20% of complexes are multivalent under conditions where MutSbeta is in molar excess over PCNA. Conformational studies indicate that the two proteins associate in an end-to-end fashion in solution. Surprisingly, mutation of the PCNA-binding motif of MutSbeta not only abolishes PCNA binding, but unlike MutSalpha, also dramatically attenuates MutSbeta-MutLalpha interaction, MutLalpha endonuclease activation, and bidirectional mismatch repair. As predicted by these findings, PCNA competes with MutLalpha for binding to MutSbeta, an effect that is blocked by the cell cycle regulator p21(CIP1). We propose that MutSbeta-MutLalpha interaction is mediated in part by residues ((L/I)SRFF) embedded within the MSH3 PCNA-binding motif. To our knowledge this is the first case where residues important for PCNA binding also mediate interaction with a second protein. These findings also indicate that MutSbeta- and MutSalpha-initiated repair events differ in fundamental ways.
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Affiliation(s)
- Ravi R Iyer
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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