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Medina-Rivera M, Phelps S, Sridharan M, Becker J, Lamb N, Kumar C, Sutton M, Bielinsky A, Balakrishnan L, Surtees J. Elevated MSH2 MSH3 expression interferes with DNA metabolism in vivo. Nucleic Acids Res 2023; 51:12185-12206. [PMID: 37930834 PMCID: PMC10711559 DOI: 10.1093/nar/gkad934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 09/30/2023] [Accepted: 10/10/2023] [Indexed: 11/08/2023] Open
Abstract
The Msh2-Msh3 mismatch repair (MMR) complex in Saccharomyces cerevisiae recognizes and directs repair of insertion/deletion loops (IDLs) up to ∼17 nucleotides. Msh2-Msh3 also recognizes and binds distinct looped and branched DNA structures with varying affinities, thereby contributing to genome stability outside post-replicative MMR through homologous recombination, double-strand break repair (DSBR) and the DNA damage response. In contrast, Msh2-Msh3 promotes genome instability through trinucleotide repeat (TNR) expansions, presumably by binding structures that form from single-stranded (ss) TNR sequences. We previously demonstrated that Msh2-Msh3 binding to 5' ssDNA flap structures interfered with Rad27 (Fen1 in humans)-mediated Okazaki fragment maturation (OFM) in vitro. Here we demonstrate that elevated Msh2-Msh3 levels interfere with DNA replication and base excision repair in vivo. Elevated Msh2-Msh3 also induced a cell cycle arrest that was dependent on RAD9 and ELG1 and led to PCNA modification. These phenotypes also required Msh2-Msh3 ATPase activity and downstream MMR proteins, indicating an active mechanism that is not simply a result of Msh2-Msh3 DNA-binding activity. This study provides new mechanistic details regarding how excess Msh2-Msh3 can disrupt DNA replication and repair and highlights the role of Msh2-Msh3 protein abundance in Msh2-Msh3-mediated genomic instability.
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Affiliation(s)
- Melisa Medina-Rivera
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo NY, 14203, USA
| | - Samantha Phelps
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo NY, 14203, USA
| | - Madhumita Sridharan
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN, 46202, USA
| | - Jordan Becker
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Natalie A Lamb
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo NY, 14203, USA
| | - Charanya Kumar
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo NY, 14203, USA
| | - Mark D Sutton
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo NY, 14203, USA
| | - Anja Bielinsky
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Lata Balakrishnan
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN, 46202, USA
| | - Jennifer A Surtees
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo NY, 14203, USA
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2
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Ma N, Jin A, Sun Y, Jin Y, Sun Y, Xiao Q, Sha X, Yu F, Yang L, Liu W, Gao X, Zhang X, Li L. Comprehensive investigating of MMR gene in hepatocellular carcinoma with chronic hepatitis B virus infection in Han Chinese population. Front Oncol 2023; 13:1124459. [PMID: 37035153 PMCID: PMC10079871 DOI: 10.3389/fonc.2023.1124459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 03/09/2023] [Indexed: 04/11/2023] Open
Abstract
Hepatocellular carcinoma associated with chronic hepatitis B virus infection seriously affects human health. Present studies suggest that genetic susceptibility plays an important role in the mechanism of cancer development. Therefore, this study focused on single nucleotide polymorphisms (SNPs) of MMR genes associated with HBV-HCC. Five groups of participants were included in this study, which were healthy control group (HC), spontaneous clearance (SC), chronic hepatitis B group (CHB), HBV-related liver cirrhosis group (LC) and HBV-related hepatocellular carcinoma group (HBV-HCC). A total of 3128 participants met the inclusion and exclusion criteria for this study. 20 polymorphic loci on MSH2, MSH3 and MSH6 were selected for genotyping. There were four case-control studies, which were HC vs. HCC, SC vs. HCC, CHB vs. HCC and LC vs. HCC. We used Hardy-Weinberg equilibrium test, unconditional logistic regression, haplotype analysis, and gene-gene interaction for genetic analysis. Ultimately, after excluding confounding factors such as age, gender, smoking and drinking, 12 polymorphisms were found to be associated with genetic susceptibility to HCC. Haplotype analysis showed the risk haplotype GTTT (rs1805355_G, rs3776968_T, rs1428030_C, rs181747_C) was more frequent in the HCC group compared with the HC group. The GMDR analysis showed that the best interaction model was the three-factor model of MSH2-rs1981928, MSH3-rs26779 and MSH6-rs2348244 in SC vs. HCC group (P=0.001). In addition, we found multiplicative or additive interactions between genes in our selected SNPs. These findings provide new ideas to further explore the etiology and pathogenesis of HCC. We have attempted to explain the molecular mechanisms by which certain SNPs (MSH2-rs4952887, MSH3-rs26779, MSH3-rs181747 and MSH3-rs32950) affect genetic susceptibility to HCC from the perspectives of eQTL, TFBS, cell cycle and so on. We also explained the results of haplotypes and gene-gene interactions. These findings provide new ideas to further explore the etiology and pathogenesis of HCC.
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Affiliation(s)
- Ning Ma
- Hebei Key Laboratory of Environment and Human Health, Department of Social Medicine and Health Care Management, School of Public Health, Hebei Medical University, Shijiazhuang, China
| | - Ao Jin
- Hebei Key Laboratory of Environment and Human Health, Department of Epidemiology and Statistics, School of Public Health, Hebei Medical University, Shijiazhuang, China
| | - Yitong Sun
- Hebei Key Laboratory of Environment and Human Health, Department of Epidemiology and Statistics, School of Public Health, Hebei Medical University, Shijiazhuang, China
| | - Yiyao Jin
- Hebei Key Laboratory of Environment and Human Health, Department of Epidemiology and Statistics, School of Public Health, Hebei Medical University, Shijiazhuang, China
| | - Yucheng Sun
- Hebei Key Laboratory of Environment and Human Health, Department of Epidemiology and Statistics, School of Public Health, Hebei Medical University, Shijiazhuang, China
| | - Qian Xiao
- Hebei Key Laboratory of Environment and Human Health, Department of Epidemiology and Statistics, School of Public Health, Hebei Medical University, Shijiazhuang, China
| | - XuanYi Sha
- Hebei Key Laboratory of Environment and Human Health, School of Basic Medicine, Hebei Medical University, Shijiazhuang, China
| | - Fengxue Yu
- The Hebei Key Laboratory of Gastroenterology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Lei Yang
- Hebei Key Laboratory of Environment and Human Health, Department of Epidemiology and Statistics, School of Public Health, Hebei Medical University, Shijiazhuang, China
| | - Wenxuan Liu
- Hebei Key Laboratory of Environment and Human Health, Department of Epidemiology and Statistics, School of Public Health, Hebei Medical University, Shijiazhuang, China
| | - Xia Gao
- Hebei Key Laboratory of Environment and Human Health, Department of Epidemiology and Statistics, School of Public Health, Hebei Medical University, Shijiazhuang, China
| | - Xiaolin Zhang
- Hebei Key Laboratory of Environment and Human Health, Department of Epidemiology and Statistics, School of Public Health, Hebei Medical University, Shijiazhuang, China
- *Correspondence: Xiaolin Zhang, ; Lu Li,
| | - Lu Li
- Hebei Key Laboratory of Environment and Human Health, Department of Social Medicine and Health Care Management, School of Public Health, Hebei Medical University, Shijiazhuang, China
- *Correspondence: Xiaolin Zhang, ; Lu Li,
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3
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Britton BM, London JA, Martin-Lopez J, Jones ND, Liu J, Lee JB, Fishel R. Exploiting the distinctive properties of the bacterial and human MutS homolog sliding clamps on mismatched DNA. J Biol Chem 2022; 298:102505. [PMID: 36126773 PMCID: PMC9597889 DOI: 10.1016/j.jbc.2022.102505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 09/13/2022] [Accepted: 09/15/2022] [Indexed: 12/30/2022] Open
Abstract
MutS homologs (MSHs) are highly conserved core components of DNA mismatch repair. Mismatch recognition provokes ATP-binding by MSH proteins that drives a conformational transition from a short-lived lesion-searching clamp to an extremely stable sliding clamp on the DNA. Here, we have expanded on previous bulk biochemical studies to examine the stability, lifetime, and kinetics of bacterial and human MSH sliding clamps on mismatched DNA using surface plasmon resonance and single-molecule analysis of fluorescently labeled proteins. We found that ATP-bound MSH complexes bound to blocked-end or very long mismatched DNAs were extremely stable over a range of ionic conditions. These observations underpinned the development of a high-throughput Förster resonance energy transfer system that specifically detects the formation of MSH sliding clamps on mismatched DNA. The Förster resonance energy transfer system is capable of distinguishing between HsMSH2-HsMSH3 and HsMSH2-HsMSH6 and appears suitable for chemical inhibitor screens. Taken together, our results provide additional insight into MSH sliding clamps as well as methods to distinguish their functions in mismatch repair.
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Affiliation(s)
- Brooke M Britton
- Department of Cancer Biology and Genetics, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - James A London
- Department of Cancer Biology and Genetics, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Juana Martin-Lopez
- Department of Cancer Biology and Genetics, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Nathan D Jones
- Department of Cancer Biology and Genetics, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Jiaquan Liu
- Department of Cancer Biology and Genetics, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Jong-Bong Lee
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, Korea; Interdisciplinary Bioscience and Bioengineering, POSTECH, Pohang, Korea
| | - Richard Fishel
- Department of Cancer Biology and Genetics, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.
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The unstructured linker of Mlh1 contains a motif required for endonuclease function which is mutated in cancers. Proc Natl Acad Sci U S A 2022; 119:e2212870119. [PMID: 36215471 PMCID: PMC9586283 DOI: 10.1073/pnas.2212870119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
DNA mismatch repair (MMR) prevents mutations caused by DNA-replication errors and suppresses multiple types of cancers. During MMR, the Mlh1-Pms1 complex is recruited to mispair-containing DNA and nicks the newly replicated DNA strand, targeting it for degradation and resynthesis. Here, we identified an amino acid sequence within the unstructured linker of Mlh1 required for endonuclease activity. This sequence functioned when moved within the Mlh1 linker or when moved to the Pms1 linker. These results reveal a functional role for the intrinsically disordered region, which is conserved from yeast to humans and is mutated in cancer, suggesting that it organizes the catalytically active complex even though the required sequence can be distant from the active site. Eukaryotic DNA mismatch repair (MMR) depends on recruitment of the Mlh1-Pms1 endonuclease (human MLH1-PMS2) to mispaired DNA. Both Mlh1 and Pms1 contain a long unstructured linker that connects the N- and carboxyl-terminal domains. Here, we demonstrated the Mlh1 linker contains a conserved motif (Saccharomyces cerevisiae residues 391–415) required for MMR. The Mlh1-R401A,D403A-Pms1 linker motif mutant protein was defective for MMR and endonuclease activity in vitro, even though the conserved motif could be >750 Å from the carboxyl-terminal endonuclease active site or the N-terminal adenosine triphosphate (ATP)-binding site. Peptides encoding this motif inhibited wild-type Mlh1-Pms1 endonuclease activity. The motif functioned in vivo at different sites within the Mlh1 linker and within the Pms1 linker. Motif mutations in human cancers caused a loss-of-function phenotype when modeled in S. cerevisiae. These results suggest that the Mlh1 motif promotes the PCNA-activated endonuclease activity of Mlh1-Pms1 via interactions with DNA, PCNA, RFC, or other domains of the Mlh1-Pms1 complex.
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5
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DuPrie ML, Palacio T, Calil FA, Kolodner RD, Putnam CD. Mlh1 interacts with both Msh2 and Msh6 for recruitment during mismatch repair. DNA Repair (Amst) 2022; 119:103405. [PMID: 36122480 PMCID: PMC9639671 DOI: 10.1016/j.dnarep.2022.103405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 08/30/2022] [Accepted: 09/10/2022] [Indexed: 11/29/2022]
Abstract
Eukaryotic DNA mismatch repair (MMR) initiates through mispair recognition by the MutS homologs Msh2-Msh6 and Msh2-Msh3 and subsequent recruitment of the MutL homologs Mlh1-Pms1 (human MLH1-PMS2). In bacteria, MutL is recruited by interactions with the connector domain of one MutS subunit and the ATPase and core domains of the other MutS subunit. Analysis of the S. cerevisiae and human homologs have only identified an interaction between the Msh2 connector domain and Mlh1. Here we investigated whether a conserved Msh6 ATPase/core domain-Mlh1 interaction and an Msh2-Msh6 interaction with Pms1 also act in MMR. Mutations in MLH1 affecting interactions with both the Msh2 and Msh6 interfaces caused MMR defects, whereas equivalent pms1 mutations did not cause MMR defects. Mutant Mlh1-Pms1 complexes containing Mlh1 amino acid substitutions were defective for recruitment to mispaired DNA by Msh2-Msh6, did not support MMR in reconstituted Mlh1-Pms1-dependent MMR reactions in vitro, but were proficient in Msh2-Msh6-independent Mlh1-Pms1 endonuclease activity. These results indicate that Mlh1, the common subunit of the Mlh1-Pms1, Mlh1-Mlh2, and Mlh1-Mlh3 complexes, but not Pms1, is recruited by Msh2-Msh6 through interactions with both of its subunits.
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Affiliation(s)
- Matthew L DuPrie
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0660, USA
| | - Tatiana Palacio
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0660, USA
| | - Felipe A Calil
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0660, USA
| | - Richard D Kolodner
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0660, USA; Department of Cellular and Molecular Medicine University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0660, USA; Moores-UCSD Cancer Center University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0660, USA; Institute of Genomic Medicine University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0660, USA
| | - Christopher D Putnam
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0660, USA; Department of Medicine University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0660, USA.
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6
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Lamb NA, Bard JE, Loll-Krippleber R, Brown GW, Surtees JA. Complex mutation profiles in mismatch repair and ribonucleotide reductase mutants reveal novel repair substrate specificity of MutS homolog (MSH) complexes. Genetics 2022; 221:6605222. [PMID: 35686905 PMCID: PMC9339293 DOI: 10.1093/genetics/iyac092] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/24/2022] [Indexed: 12/30/2022] Open
Abstract
Determining mutation signatures is standard for understanding the etiology of human tumors and informing cancer treatment. Multiple determinants of DNA replication fidelity prevent mutagenesis that leads to carcinogenesis, including the regulation of free deoxyribonucleoside triphosphate pools by ribonucleotide reductase and repair of replication errors by the mismatch repair system. We identified genetic interactions between rnr1 alleles that skew and/or elevate deoxyribonucleoside triphosphate levels and mismatch repair gene deletions. These defects indicate that the rnr1 alleles lead to increased mutation loads that are normally acted upon by mismatch repair. We then utilized a targeted deep-sequencing approach to determine mutational profiles associated with mismatch repair pathway defects. By combining rnr1 and msh mutations to alter and/or increase deoxyribonucleoside triphosphate levels and alter the mutational load, we uncovered previously unreported specificities of Msh2-Msh3 and Msh2-Msh6. Msh2-Msh3 is uniquely able to direct the repair of G/C single-base deletions in GC runs, while Msh2-Msh6 specifically directs the repair of substitutions that occur at G/C dinucleotides. We also identified broader sequence contexts that influence variant profiles in different genetic backgrounds. Finally, we observed that the mutation profiles in double mutants were not necessarily an additive relationship of mutation profiles in single mutants. Our results have implications for interpreting mutation signatures from human tumors, particularly when mismatch repair is defective.
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Affiliation(s)
- Natalie A Lamb
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
| | - Jonathan E Bard
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA,University at Buffalo Genomics and Bioinformatics Core, State University of New York at Buffalo, Buffalo, NY 14203, USA
| | - Raphael Loll-Krippleber
- Department of Biochemistry and Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Grant W Brown
- Department of Biochemistry and Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Jennifer A Surtees
- Corresponding author: Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Rm 4215, 955 Main Street, Buffalo, NY 14203, USA.
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7
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Perne C, Peters S, Cartolano M, Horpaopan S, Grimm C, Altmüller J, Sommer AK, Hillmer AM, Thiele H, Odenthal M, Möslein G, Adam R, Sivalingam S, Kirfel J, Schweiger MR, Peifer M, Spier I, Aretz S. Variant profiling of colorectal adenomas from three patients of two families with MSH3-related adenomatous polyposis. PLoS One 2021; 16:e0259185. [PMID: 34843512 PMCID: PMC8629245 DOI: 10.1371/journal.pone.0259185] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 10/14/2021] [Indexed: 12/12/2022] Open
Abstract
The spectrum of somatic genetic variation in colorectal adenomas caused by biallelic pathogenic germline variants in the MSH3 gene, was comprehensively analysed to characterise mutational signatures and identify potential driver genes and pathways of MSH3-related tumourigenesis. Three patients from two families with MSH3-associated polyposis were included. Whole exome sequencing of nine adenomas and matched normal tissue was performed. The amount of somatic variants in the MSH3-deficient adenomas and the pattern of single nucleotide variants (SNVs) was similar to sporadic adenomas, whereas the fraction of small insertions/deletions (indels) (21-42% of all small variants) was significantly higher. Interestingly, pathogenic somatic APC variants were found in all but one adenoma. The vast majority (12/13) of these were di-, tetra-, or penta-base pair (bp) deletions. The fraction of APC indels was significantly higher than that reported in patients with familial adenomatous polyposis (FAP) (p < 0.01) or in sporadic adenomas (p < 0.0001). In MSH3-deficient adenomas, the occurrence of APC indels in a repetitive sequence context was significantly higher than in FAP patients (p < 0.01). In addition, the MSH3-deficient adenomas harboured one to five (recurrent) somatic variants in 13 established or candidate driver genes for early colorectal carcinogenesis, including ACVR2A and ARID genes. Our data suggest that MSH3-related colorectal carcinogenesis seems to follow the classical APC-driven pathway. In line with the specific function of MSH3 in the mismatch repair (MMR) system, we identified a characteristic APC mutational pattern in MSH3-deficient adenomas, and confirmed further driver genes for colorectal tumourigenesis.
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Affiliation(s)
- Claudia Perne
- Institute of Human Genetics, Medical Faculty, University of Bonn, Bonn, Germany
- Center for Hereditary Tumor Syndromes, University Hospital Bonn, Bonn, Germany
| | - Sophia Peters
- Institute of Human Genetics, Medical Faculty, University of Bonn, Bonn, Germany
| | - Maria Cartolano
- Department of Translational Genomics, Center of Integrated Oncology Cologne-Bonn, Medical Faculty, University of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Sukanya Horpaopan
- Department of Anatomy, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand
| | - Christina Grimm
- Institute for Translational Epigenetics, Medical Faculty and University Clinic Cologne, University of Cologne, Cologne, Germany
| | - Janine Altmüller
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
- Cologne Center for Genomics (CCG), Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
- Berlin Institute of Health at Charité, Core Facility Genomics, Berlin, Germany
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Anna K. Sommer
- Institute of Human Genetics, Medical Faculty, University of Bonn, Bonn, Germany
| | - Axel M. Hillmer
- Institute of Pathology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Holger Thiele
- Cologne Center for Genomics (CCG), Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Margarete Odenthal
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
- Institute of Pathology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Gabriela Möslein
- Zentrum für Hereditäre Tumore, BETHESDA Khs. Duisburg, Duisburg, Germany
| | - Ronja Adam
- Cancer Center Amsterdam, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Sugirthan Sivalingam
- Core Unit for Bioinformatics Data Analysis, Medical Faculty, University of Bonn, Bonn, Germany
- Institute for Genomic Statistics and Bioinformatics, Medical Faculty, University of Bonn, Bonn, Germany
- Institute for Medical Biometry, Informatics and Epidemiology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Jutta Kirfel
- Institute of Pathology, University of Lübeck, Lübeck, Germany
| | - Michal R. Schweiger
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
- Institute for Translational Epigenetics, Medical Faculty and University Clinic Cologne, University of Cologne, Cologne, Germany
| | - Martin Peifer
- Department of Translational Genomics, Center of Integrated Oncology Cologne-Bonn, Medical Faculty, University of Cologne, Cologne, Germany
| | - Isabel Spier
- Institute of Human Genetics, Medical Faculty, University of Bonn, Bonn, Germany
- Center for Hereditary Tumor Syndromes, University Hospital Bonn, Bonn, Germany
| | - Stefan Aretz
- Institute of Human Genetics, Medical Faculty, University of Bonn, Bonn, Germany
- Center for Hereditary Tumor Syndromes, University Hospital Bonn, Bonn, Germany
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8
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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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Tesfahun AN, Alexeeva M, Tomkuvienė M, Arshad A, Guragain P, Klungland A, Klimašauskas S, Ruoff P, Bjelland S. Alleviation of C⋅C Mismatches in DNA by the Escherichia coli Fpg Protein. Front Microbiol 2021; 12:608839. [PMID: 34276575 PMCID: PMC8278400 DOI: 10.3389/fmicb.2021.608839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 05/20/2021] [Indexed: 11/18/2022] Open
Abstract
DNA polymerase III mis-insertion may, where not corrected by its 3′→ 5′ exonuclease or the mismatch repair (MMR) function, result in all possible non-cognate base pairs in DNA generating base substitutions. The most thermodynamically unstable base pair, the cytosine (C)⋅C mismatch, destabilizes adjacent base pairs, is resistant to correction by MMR in Escherichia coli, and its repair mechanism remains elusive. We present here in vitro evidence that C⋅C mismatch can be processed by base excision repair initiated by the E. coli formamidopyrimidine-DNA glycosylase (Fpg) protein. The kcat for C⋅C is, however, 2.5 to 10 times lower than for its primary substrate 8-oxoguanine (oxo8G)⋅C, but approaches those for 5,6-dihydrothymine (dHT)⋅C and thymine glycol (Tg)⋅C. The KM values are all in the same range, which indicates efficient recognition of C⋅C mismatches in DNA. Fpg activity was also exhibited for the thymine (T)⋅T mismatch and for N4- and/or 5-methylated C opposite C or T, Fpg activity being enabled on a broad spectrum of DNA lesions and mismatches by the flexibility of the active site loop. We hypothesize that Fpg plays a role in resolving C⋅C in particular, but also other pyrimidine⋅pyrimidine mismatches, which increases survival at the cost of some mutagenesis.
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Affiliation(s)
- Almaz Nigatu Tesfahun
- Department of Chemistry, Bioscience and Environmental Technology, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
| | - Marina Alexeeva
- Department of Chemistry, Bioscience and Environmental Technology, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
| | - Miglė Tomkuvienė
- Department of Biological DNA Modification, Institute of Biotechnology, Vilnius University, Vilnius, Lithuania
| | - Aysha Arshad
- Department of Chemistry, Bioscience and Environmental Technology, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
| | - Prashanna Guragain
- Department of Chemistry, Bioscience and Environmental Technology, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
| | - Arne Klungland
- Department of Microbiology, Oslo University Hospital, Oslo, Norway.,Department of Molecular Medicine, Life Sciences Center, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Saulius Klimašauskas
- Department of Biological DNA Modification, Institute of Biotechnology, Vilnius University, Vilnius, Lithuania
| | - Peter Ruoff
- Department of Chemistry, Bioscience and Environmental Technology, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
| | - Svein Bjelland
- Department of Chemistry, Bioscience and Environmental Technology, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway.,Department of Clinical Molecular Biology, Akershus University Hospital, Lørenskog, Norway
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10
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Rahman MM, Mohiuddin M, Shamima Keka I, Yamada K, Tsuda M, Sasanuma H, Andreani J, Guerois R, Borde V, Charbonnier JB, Takeda S. Genetic evidence for the involvement of mismatch repair proteins, PMS2 and MLH3, in a late step of homologous recombination. J Biol Chem 2021; 295:17460-17475. [PMID: 33453991 DOI: 10.1074/jbc.ra120.013521] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 09/28/2020] [Indexed: 12/15/2022] Open
Abstract
Homologous recombination (HR) repairs DNA double-strand breaks using intact homologous sequences as template DNA. Broken DNA and intact homologous sequences form joint molecules (JMs), including Holliday junctions (HJs), as HR intermediates. HJs are resolved to form crossover and noncrossover products. A mismatch repair factor, MLH3 endonuclease, produces the majority of crossovers during meiotic HR, but it remains elusive whether mismatch repair factors promote HR in nonmeiotic cells. We disrupted genes encoding the MLH3 and PMS2 endonucleases in the human B cell line, TK6, generating null MLH3-/- and PMS2-/- mutant cells. We also inserted point mutations into the endonuclease motif of MLH3 and PMS2 genes, generating endonuclease death MLH3DN/DN and PMS2EK/EK cells. MLH3-/- and MLH3DN/DN cells showed a very similar phenotype, a 2.5-fold decrease in the frequency of heteroallelic HR-dependent repair of restriction enzyme-induced double-strand breaks. PMS2-/- and PMS2EK/EK cells showed a phenotype very similar to that of the MLH3 mutants. These data indicate that MLH3 and PMS2 promote HR as an endonuclease. The MLH3DN/DN and PMS2EK/EK mutations had an additive effect on the heteroallelic HR. MLH3DN/DN/PMS2EK/EK cells showed normal kinetics of γ-irradiation-induced Rad51 foci but a significant delay in the resolution of Rad51 foci and a 3-fold decrease in the number of cisplatin-induced sister chromatid exchanges. The ectopic expression of the Gen1 HJ re-solvase partially reversed the defective heteroallelic HR of MLH3DN/DN/PMS2EK/EK cells. Taken together, we propose that MLH3 and PMS2 promote HR as endonucleases, most likely by processing JMs in mammalian somatic cells.
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Affiliation(s)
- Md Maminur Rahman
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Mohiuddin Mohiuddin
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Islam Shamima Keka
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kousei Yamada
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Masataka Tsuda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hiroyuki Sasanuma
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Jessica Andreani
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique (CEA), CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Raphael Guerois
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique (CEA), CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Valerie Borde
- Institut Curie, CNRS, UMR3244, PSL Research University, Paris, France
| | - Jean-Baptiste Charbonnier
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique (CEA), CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Shunichi Takeda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
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11
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Comprehensive Genomic Characterization of Fifteen Early-Onset Lynch-Like Syndrome Colorectal Cancers. Cancers (Basel) 2021; 13:cancers13061259. [PMID: 33809179 PMCID: PMC7999079 DOI: 10.3390/cancers13061259] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 03/04/2021] [Accepted: 03/09/2021] [Indexed: 12/30/2022] Open
Abstract
Simple Summary The most prevalent type of hereditary colorectal cancer is called Lynch syndrome and it is characterized by a tumor phenotype called microsatellite instability (MSI). This disease is a consequence of germline (inheritable) variants in any of the four mismatch repair (MMR) DNA genes, being their identification essential to ensure their appropriate diagnosis and implementation of preventive measurements. Nevertheless, only 50% of patients with MSI and suspected Lynch syndrome actually carry a germline pathogenic variant in an MMR gene that explains the clinical entity. The remaining 50% are termed Lynch-like syndrome, and their causes remain unknown. In this work, we tried to elucidate the molecular mechanisms that underlie this rare entity in a group of early-onset Lynch-like syndrome colorectal cancer, through whole-exome sequencing of germline and tumor samples. We observed that one-third of these patients have somatic alterations in genes associated with the MMR system and that these could be the mechanism causing their unexplained MSI. Furthermore, we found that patients who showed biallelic somatic alterations also carried germline variants in new candidate genes associated with DNA repair functions and that this could be, partly, the cause of the early onset in this cohort. Abstract Lynch-like syndrome (LLS) is an increasingly common clinical challenge with an underlying molecular basis mostly unknown. To shed light onto it, we focused on a very young LLS early-onset colorectal cancer (CRC) cohort (diagnosis ≤ 40 y.o.), performing germline and tumor whole-exome sequencing (WES) of 15 patients, and additionally analyzing their corresponding tumor mutational burden (TMB) and mutational signatures. We identified four cases (27%) with double somatic putative variants in mismatch repair (MMR) core genes, as well as three additional cases (20%) with double MSH3 somatic alterations in tumors with unexplained MSH2/MSH6 loss of expression, and two cases (13%) with POLD1 potential biallelic alterations. Average TMB was significantly higher for LLS cases with double somatic alterations. Lastly, nine predicted deleterious variants in genes involved in the DNA repair functions and/or previously associated with CRC were found in nine probands, four of which also showed MMR biallelic somatic inactivation. In conclusion, we contribute new insights into LLS CRC, postulating MSH3 and POLD1 double somatic alterations as an underlying cause of a microsatellite instability (MSI) phenotype, proposing intrinsic biological differences between LLS with and without somatic alterations, and suggesting new predisposing candidate genes in this scenario.
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12
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Abstract
DNA mismatch repair (MMR) is a highly conserved genome stabilizing pathway that corrects DNA replication errors, limits chromosomal rearrangements, and mediates the cellular response to many types of DNA damage. Counterintuitively, MMR is also involved in the generation of mutations, as evidenced by its role in causing somatic triplet repeat expansion in Huntington’s disease (HD) and other neurodegenerative disorders. In this review, we discuss the current state of mechanistic knowledge of MMR and review the roles of key enzymes in this pathway. We also present the evidence for mutagenic function of MMR in CAG repeat expansion and consider mechanistic hypotheses that have been proposed. Understanding the role of MMR in CAG expansion may shed light on potential avenues for therapeutic intervention in HD.
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Affiliation(s)
- Ravi R Iyer
- CHDI Management/CHDI Foundation, Princeton, NJ, USA
| | - Anna Pluciennik
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
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13
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Carbone M, Arron ST, Beutler B, Bononi A, Cavenee W, Cleaver JE, Croce CM, D'Andrea A, Foulkes WD, Gaudino G, Groden JL, Henske EP, Hickson ID, Hwang PM, Kolodner RD, Mak TW, Malkin D, Monnat RJ, Novelli F, Pass HI, Petrini JH, Schmidt LS, Yang H. Tumour predisposition and cancer syndromes as models to study gene-environment interactions. Nat Rev Cancer 2020; 20:533-549. [PMID: 32472073 PMCID: PMC8104546 DOI: 10.1038/s41568-020-0265-y] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/23/2020] [Indexed: 12/18/2022]
Abstract
Cell division and organismal development are exquisitely orchestrated and regulated processes. The dysregulation of the molecular mechanisms underlying these processes may cause cancer, a consequence of cell-intrinsic and/or cell-extrinsic events. Cellular DNA can be damaged by spontaneous hydrolysis, reactive oxygen species, aberrant cellular metabolism or other perturbations that cause DNA damage. Moreover, several environmental factors may damage the DNA, alter cellular metabolism or affect the ability of cells to interact with their microenvironment. While some environmental factors are well established as carcinogens, there remains a large knowledge gap of others owing to the difficulty in identifying them because of the typically long interval between carcinogen exposure and cancer diagnosis. DNA damage increases in cells harbouring mutations that impair their ability to correctly repair the DNA. Tumour predisposition syndromes in which cancers arise at an accelerated rate and in different organs - the equivalent of a sensitized background - provide a unique opportunity to examine how gene-environment interactions influence cancer risk when the initiating genetic defect responsible for malignancy is known. Understanding the molecular processes that are altered by specific germline mutations, environmental exposures and related mechanisms that promote cancer will allow the design of novel and effective preventive and therapeutic strategies.
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Affiliation(s)
- Michele Carbone
- Thoracic Oncology, University of Hawaii Cancer Center, Honolulu, HI, USA.
| | - Sarah T Arron
- STA, JEC, Department of Dermatology, University of California, San Francisco, San Francisco, CA, USA
| | - Bruce Beutler
- Center for Genetic Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Angela Bononi
- Thoracic Oncology, University of Hawaii Cancer Center, Honolulu, HI, USA
| | - Webster Cavenee
- Ludwig Institute, University of California, San Diego, San Diego, CA, USA
| | - James E Cleaver
- STA, JEC, Department of Dermatology, University of California, San Francisco, San Francisco, CA, USA
| | - Carlo M Croce
- Department of Cancer Biology and Genetics, Ohio State University, Columbus, OH, USA
| | - Alan D'Andrea
- Dana Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - William D Foulkes
- Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Giovanni Gaudino
- Thoracic Oncology, University of Hawaii Cancer Center, Honolulu, HI, USA
| | | | - Elizabeth P Henske
- Center for LAM Research, Brigham & Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Ian D Hickson
- Center for Chromosome Stability, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
- Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Paul M Hwang
- Cardiovascular Branch, National Institutes of Health, Bethesda, MD, USA
| | - Richard D Kolodner
- Ludwig Institute, University of California, San Diego, San Diego, CA, USA
| | - Tak W Mak
- Princess Margaret Cancer Center, University of Toronto, Toronto, ON, Canada
| | - David Malkin
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Raymond J Monnat
- Department Pathology, Washington University, Seattle, WA, USA
- Department of Genome Science, Washington University, Seattle, WA, USA
| | - Flavia Novelli
- Thoracic Oncology, University of Hawaii Cancer Center, Honolulu, HI, USA
| | - Harvey I Pass
- Department of Cardiovascular Surgery, New York University, New York, NY, USA
| | - John H Petrini
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Laura S Schmidt
- Urologic Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Haining Yang
- Thoracic Oncology, University of Hawaii Cancer Center, Honolulu, HI, USA
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14
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Novel Genetic Markers for Early Detection of Elevated Breast Cancer Risk in Women. Int J Mol Sci 2019; 20:ijms20194828. [PMID: 31569399 PMCID: PMC6801521 DOI: 10.3390/ijms20194828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 09/20/2019] [Accepted: 09/25/2019] [Indexed: 12/25/2022] Open
Abstract
This study suggests that two newly discovered variants in the MSH2 gene, which codes for a DNA mismatch repair (MMR) protein, can be associated with a high risk of breast cancer. While variants in the MSH2 gene are known to be linked with an elevated cancer risk, the MSH2 gene is not a part of the standard kit for testing patients for elevated breast cancer risk. Here we used the results of genetic testing of women diagnosed with breast cancer, but who did not have variants in BRCA1 and BRCA2 genes. Instead, the test identified four variants with unknown significance (VUS) in the MSH2 gene. Here, we carried in silico analysis to develop a classifier that can distinguish pathogenic from benign mutations in MSH2 genes taken from ClinVar. The classifier was then used to classify VUS in MSH2 genes, and two of them, p.Ala272Val and p.Met592Val, were predicted to be pathogenic mutations. These two mutations were found in women with breast cancer who did not have mutations in BRCA1 and BRCA2 genes, and thus they are suggested to be considered as new bio-markers for the early detection of elevated breast cancer risk. However, before this is done, an in vitro validation of mutation pathogenicity is needed and, moreover, the presence of these mutations should be demonstrated in a higher number of patients or in families with breast cancer history.
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15
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Graham WJ, Putnam CD, Kolodner RD. The properties of Msh2-Msh6 ATP binding mutants suggest a signal amplification mechanism in DNA mismatch repair. J Biol Chem 2018; 293:18055-18070. [PMID: 30237169 PMCID: PMC6254361 DOI: 10.1074/jbc.ra118.005439] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 09/17/2018] [Indexed: 11/30/2022] Open
Abstract
DNA mismatch repair (MMR) corrects mispaired DNA bases and small insertion/deletion loops generated by DNA replication errors. After binding a mispair, the eukaryotic mispair recognition complex Msh2–Msh6 binds ATP in both of its nucleotide-binding sites, which induces a conformational change resulting in the formation of an Msh2–Msh6 sliding clamp that releases from the mispair and slides freely along the DNA. However, the roles that Msh2–Msh6 sliding clamps play in MMR remain poorly understood. Here, using Saccharomyces cerevisiae, we created Msh2 and Msh6 Walker A nucleotide–binding site mutants that have defects in ATP binding in one or both nucleotide-binding sites of the Msh2–Msh6 heterodimer. We found that these mutations cause a complete MMR defect in vivo. The mutant Msh2–Msh6 complexes exhibited normal mispair recognition and were proficient at recruiting the MMR endonuclease Mlh1–Pms1 to mispaired DNA. At physiological (2.5 mm) ATP concentration, the mutant complexes displayed modest partial defects in supporting MMR in reconstituted Mlh1–Pms1-independent and Mlh1–Pms1-dependent MMR reactions in vitro and in activation of the Mlh1–Pms1 endonuclease and showed a more severe defect at low (0.1 mm) ATP concentration. In contrast, five of the mutants were completely defective and one was mostly defective for sliding clamp formation at high and low ATP concentrations. These findings suggest that mispair-dependent sliding clamp formation triggers binding of additional Msh2–Msh6 complexes and that further recruitment of additional downstream MMR proteins is required for signal amplification of mispair binding during MMR.
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Affiliation(s)
| | - Christopher D Putnam
- From the Ludwig Institute for Cancer Research San Diego,; Departments of Medicine and
| | - Richard D Kolodner
- From the Ludwig Institute for Cancer Research San Diego,; Cellular and Molecular Medicine,; Moores-UCSD Cancer Center, and; Institute of Genomic Medicine, University of California School of Medicine, San Diego, La Jolla, California 92093-0669.
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16
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Sarma S, Pandey AK, Sharma K, Ravi M, Sreelakshmi Y, Sharma R. MutS-Homolog2 silencing generates tetraploid meiocytes in tomato ( Solanum lycopersicum). PLANT DIRECT 2018; 2:e00017. [PMID: 31245679 PMCID: PMC6508528 DOI: 10.1002/pld3.17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Revised: 09/07/2017] [Accepted: 09/12/2017] [Indexed: 05/16/2023]
Abstract
MSH2 is the core protein of MutS-homolog family involved in recognition and repair of the errors in the DNA. While other members of MutS-homolog family reportedly regulate mitochondrial stability, meiosis, and fertility, MSH2 is believed to participate mainly in mismatch repair. The search for polymorphism in MSH2 sequence in tomato accessions revealed both synonymous and nonsynonymous SNPs; however, SIFT algorithm predicted that none of the SNPs influenced MSH2 protein function. The silencing of MSH2 gene expression by RNAi led to phenotypic abnormalities in highly silenced lines, particularly in the stamens with highly reduced pollen formation. MSH2 silencing exacerbated formation of UV-B-induced thymine dimers and blocked light-induced repair of the dimers. The MSH2 silencing also affected the progression of male meiosis to a varying degree with either halt of meiosis at zygotene stage or formation of diploid tetrads. The immunostaining of male meiocytes with centromere localized CENPC (centromere protein C) antibody showed the presence of 48 univalent along with 24 bivalent chromosomes suggesting abnormal tetraploid meiosis. The mitotic cells of root tips of silenced lines showed diploid nuclei but lacked intervening cell plates leading to cells with syncytial nuclei. Thus, we speculate that tetraploid pollen mother cells may have arisen due to the fusion of syncytial nuclei before the onset of meiosis. It is likely that in addition to mismatch repair (MMR), MSH2 may have an additional role in regulating ploidy stability.
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Affiliation(s)
- Supriya Sarma
- Repository of Tomato Genomics ResourcesDepartment of Plant SciencesSchool of Life SciencesUniversity of HyderabadHyderabadIndia
- Present address:
Centre for Cellular and Molecular BiologyHyderabadIndia
| | - Arun Kumar Pandey
- Repository of Tomato Genomics ResourcesDepartment of Plant SciencesSchool of Life SciencesUniversity of HyderabadHyderabadIndia
- Present address:
International Crops Research Institute for the Semi‐Arid Tropics (ICRISAT)HyderabadIndia
| | - Kapil Sharma
- Repository of Tomato Genomics ResourcesDepartment of Plant SciencesSchool of Life SciencesUniversity of HyderabadHyderabadIndia
| | - Maruthachalam Ravi
- School of BiologyIndian Institute of Science Education and ResearchThiruvananthapuramKeralaIndia
| | - Yellamaraju Sreelakshmi
- Repository of Tomato Genomics ResourcesDepartment of Plant SciencesSchool of Life SciencesUniversity of HyderabadHyderabadIndia
| | - Rameshwar Sharma
- Repository of Tomato Genomics ResourcesDepartment of Plant SciencesSchool of Life SciencesUniversity of HyderabadHyderabadIndia
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17
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Hinrichsen I, Ackermann A, Düding T, Graband A, Filmann N, Plotz G, Zeuzem S, Brieger A. Loss of MLH1 sensitizes colon cancer cells to DNA-PKcs inhibitor KU60648. Mol Carcinog 2017; 56:1816-1824. [PMID: 28224663 DOI: 10.1002/mc.22640] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 01/30/2017] [Accepted: 02/16/2017] [Indexed: 12/15/2022]
Abstract
Germline mutations of MLH1 are responsible for tumor generation in nearly 50% of patients with Lynch Syndrome, and around 15% of sporadic colorectal cancers show MLH1-deficiency due to promotor hypermethylation. Although these tumors are of lower aggressiveness the benefit for these patients from standard chemotherapy is still under discussion. Recently, it was shown that the sensitivity to the DNA-PKcs inhibitor KU60648 is linked to loss of the MMR protein MSH3. However, loss of MSH3 is rather secondary, as a consequence of MMR-deficiency, and frequently detectable in MLH1-deficient tumors. Therefore, we examined the expression of MLH1, MSH2, MSH6, and MSH3 in different MMR-deficient and proficient cell lines and determined their sensitivity to KU60648 by analyzing cell viability and survival. MLH1-dependent ability of double strand break (DSB) repair was monitored after irradiation via γH2AX detection. A panel of 12 colon cancer cell lines, two pairs of cells, where MLH1 knock down was compared to controls with the same genetic background, and one MLH1-deficient cell line where MLH1 was overexpressed, were included. In summary, we found that MLH1 and/or MSH3-deficient cells exhibited a significantly higher sensitivity to KU60648 than MMR-proficient cells and that overexpression of MLH1 in MLH1-deficient cells resulted in a decrease of cell sensitivity. KU60648 efficiency seems to be associated with reduced DSB repair capacity. Since the molecular testing of colon tumors for MLH1 expression is a clinical standard we believe that MLH1 is a much better marker and a greater number of patients would benefit from KU60648 treatment.
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Affiliation(s)
- Inga Hinrichsen
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a.M., Germany
| | - Anne Ackermann
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a.M., Germany
| | - Tonja Düding
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a.M., Germany
| | - Annika Graband
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a.M., Germany
| | - Natalie Filmann
- Institute of Biostatistics and Mathematical Modeling, Goethe University Frankfurt, Germany
| | - Guido Plotz
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a.M., Germany
| | - Stefan Zeuzem
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a.M., Germany
| | - Angela Brieger
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a.M., Germany
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18
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Inserting Extrahelical Structures into Long DNA Substrates for Single-Molecule Studies of DNA Mismatch Repair. Methods Enzymol 2016; 582:221-238. [PMID: 28062036 DOI: 10.1016/bs.mie.2016.08.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The DNA mismatch repair (MMR) system corrects errors that occur during DNA replication. MMR needs the coordinated and highly dynamic assembly of repair enzymes at the site of the lesion. By visualizing transient intermediates of these assemblies, single-molecule approaches have shed critical insights into the mechanisms of MMR. These studies frequently require long (>20kb) DNA substrates with lesions and other extrahelical structures inserted at defined positions. DNA derived from bacteriophage λ (λ-DNA) is a high quality long (48.5kb) DNA substrate that is frequently used in single-molecule studies. Here we provide detailed protocols for site-specific incorporation of recombinant sequences and extrahelical structures into λ-DNA. We also describe how to assemble DNA curtains, and how to collect and analyze single-molecule observations of lesion recognition by MMR proteins diffusing on these DNA curtains. These protocols will facilitate future single-molecule studies of DNA transcription, replication, and repair.
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19
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Adam R, Spier I, Zhao B, Kloth M, Marquez J, Hinrichsen I, Kirfel J, Tafazzoli A, Horpaopan S, Uhlhaas S, Stienen D, Friedrichs N, Altmüller J, Laner A, Holzapfel S, Peters S, Kayser K, Thiele H, Holinski-Feder E, Marra G, Kristiansen G, Nöthen MM, Büttner R, Möslein G, Betz RC, Brieger A, Lifton RP, Aretz S. Exome Sequencing Identifies Biallelic MSH3 Germline Mutations as a Recessive Subtype of Colorectal Adenomatous Polyposis. Am J Hum Genet 2016; 99:337-51. [PMID: 27476653 DOI: 10.1016/j.ajhg.2016.06.015] [Citation(s) in RCA: 161] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 06/14/2016] [Indexed: 12/20/2022] Open
Abstract
In ∼30% of families affected by colorectal adenomatous polyposis, no germline mutations have been identified in the previously implicated genes APC, MUTYH, POLE, POLD1, and NTHL1, although a hereditary etiology is likely. To uncover further genes with high-penetrance causative mutations, we performed exome sequencing of leukocyte DNA from 102 unrelated individuals with unexplained adenomatous polyposis. We identified two unrelated individuals with differing compound-heterozygous loss-of-function (LoF) germline mutations in the mismatch-repair gene MSH3. The impact of the MSH3 mutations (c.1148delA, c.2319-1G>A, c.2760delC, and c.3001-2A>C) was indicated at the RNA and protein levels. Analysis of the diseased individuals' tumor tissue demonstrated high microsatellite instability of di- and tetranucleotides (EMAST), and immunohistochemical staining illustrated a complete loss of nuclear MSH3 in normal and tumor tissue, confirming the LoF effect and causal relevance of the mutations. The pedigrees, genotypes, and frequency of MSH3 mutations in the general population are consistent with an autosomal-recessive mode of inheritance. Both index persons have an affected sibling carrying the same mutations. The tumor spectrum in these four persons comprised colorectal and duodenal adenomas, colorectal cancer, gastric cancer, and an early-onset astrocytoma. Additionally, we detected one unrelated individual with biallelic PMS2 germline mutations, representing constitutional mismatch-repair deficiency. Potentially causative variants in 14 more candidate genes identified in 26 other individuals require further workup. In the present study, we identified biallelic germline MSH3 mutations in individuals with a suspected hereditary tumor syndrome. Our data suggest that MSH3 mutations represent an additional recessive subtype of colorectal adenomatous polyposis.
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Affiliation(s)
- Ronja Adam
- Institute of Human Genetics, University of Bonn, 53127 Bonn, Germany; Center for Hereditary Tumor Syndromes, University of Bonn, 53127 Bonn, Germany
| | - Isabel Spier
- Institute of Human Genetics, University of Bonn, 53127 Bonn, Germany; Center for Hereditary Tumor Syndromes, University of Bonn, 53127 Bonn, Germany
| | - Bixiao Zhao
- Department of Genetics, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520-8005, USA
| | - Michael Kloth
- Institute of Pathology, University of Cologne, 50937 Cologne, Germany
| | - Jonathan Marquez
- Department of Genetics, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520-8005, USA
| | - Inga Hinrichsen
- Medical Clinic 1, Biomedical Research Laboratory, Goethe-University Frankfurt, 60590 Frankfurt, Germany
| | - Jutta Kirfel
- Institute of Pathology, University of Bonn, 53127 Bonn, Germany
| | - Aylar Tafazzoli
- Institute of Human Genetics, University of Bonn, 53127 Bonn, Germany; Department of Genomics, Life & Brain Center, University of Bonn, 53127 Bonn, Germany
| | - Sukanya Horpaopan
- Institute of Human Genetics, University of Bonn, 53127 Bonn, Germany; Department of Anatomy, Faculty of Medical Science, Naresuan University, Phitsanulok, Chiang Mai 50200, Thailand
| | - Siegfried Uhlhaas
- Institute of Human Genetics, University of Bonn, 53127 Bonn, Germany
| | - Dietlinde Stienen
- Institute of Human Genetics, University of Bonn, 53127 Bonn, Germany
| | | | - Janine Altmüller
- Cologne Center for Genomics, University of Cologne, 50937 Cologne, Germany; Institute of Human Genetics, University of Cologne, 50937 Cologne, Germany
| | - Andreas Laner
- Medizinische Klinik und Poliklinik IV, Ludwig-Maximilians-University, 80336 Munich, Germany; Medical Genetics Center, 80335 Munich, Germany
| | - Stefanie Holzapfel
- Institute of Human Genetics, University of Bonn, 53127 Bonn, Germany; Center for Hereditary Tumor Syndromes, University of Bonn, 53127 Bonn, Germany
| | - Sophia Peters
- Institute of Human Genetics, University of Bonn, 53127 Bonn, Germany
| | - Katrin Kayser
- Institute of Human Genetics, University of Bonn, 53127 Bonn, Germany
| | - Holger Thiele
- Cologne Center for Genomics, University of Cologne, 50937 Cologne, Germany
| | - Elke Holinski-Feder
- Medizinische Klinik und Poliklinik IV, Ludwig-Maximilians-University, 80336 Munich, Germany; Medical Genetics Center, 80335 Munich, Germany
| | - Giancarlo Marra
- Institute of Molecular Cancer Research, University of Zurich, CH-8057 Zurich, Switzerland
| | | | - Markus M Nöthen
- Institute of Human Genetics, University of Bonn, 53127 Bonn, Germany; Department of Genomics, Life & Brain Center, University of Bonn, 53127 Bonn, Germany
| | - Reinhard Büttner
- Institute of Pathology, University of Cologne, 50937 Cologne, Germany
| | - Gabriela Möslein
- HELIOS Klinikum Wuppertal, University of Witten/Herdecke, 42283 Wuppertal, Germany
| | - Regina C Betz
- Institute of Human Genetics, University of Bonn, 53127 Bonn, Germany; Department of Genomics, Life & Brain Center, University of Bonn, 53127 Bonn, Germany
| | - Angela Brieger
- Medical Clinic 1, Biomedical Research Laboratory, Goethe-University Frankfurt, 60590 Frankfurt, Germany
| | - Richard P Lifton
- Department of Genetics, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520-8005, USA
| | - Stefan Aretz
- Institute of Human Genetics, University of Bonn, 53127 Bonn, Germany; Center for Hereditary Tumor Syndromes, University of Bonn, 53127 Bonn, Germany.
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20
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Absence of MutSβ leads to the formation of slipped-DNA for CTG/CAG contractions at primate replication forks. DNA Repair (Amst) 2016; 42:107-18. [PMID: 27155933 DOI: 10.1016/j.dnarep.2016.04.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 03/22/2016] [Accepted: 04/05/2016] [Indexed: 11/22/2022]
Abstract
Typically disease-causing CAG/CTG repeats expand, but rare affected families can display high levels of contraction of the expanded repeat amongst offspring. Understanding instability is important since arresting expansions or enhancing contractions could be clinically beneficial. The MutSβ mismatch repair complex is required for CAG/CTG expansions in mice and patients. Oddly, by unknown mechanisms MutSβ-deficient mice incur contractions instead of expansions. Replication using CTG or CAG as the lagging strand template is known to cause contractions or expansions respectively; however, the interplay between replication and repair leading to this instability remains unclear. Towards understanding how repeat contractions may arise, we performed in vitro SV40-mediated replication of repeat-containing plasmids in the presence or absence of mismatch repair. Specifically, we separated repair from replication: Replication mediated by MutSβ- and MutSα-deficient human cells or cell extracts produced slipped-DNA heteroduplexes in the contraction- but not expansion-biased replication direction. Replication in the presence of MutSβ disfavoured the retention of replication products harbouring slipped-DNA heteroduplexes. Post-replication repair of slipped-DNAs by MutSβ-proficient extracts eliminated slipped-DNAs. Thus, a MutSβ-deficiency likely enhances repeat contractions because MutSβ protects against contractions by repairing template strand slip-outs. Replication deficient in LigaseI or PCNA-interaction mutant LigaseI revealed slipped-DNA formation at lagging strands. Our results reveal that distinct mechanisms lead to expansions or contractions and support inhibition of MutSβ as a therapeutic strategy to enhance the contraction of expanded repeats.
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21
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Brown MW, Kim Y, Williams GM, Huck JD, Surtees JA, Finkelstein IJ. Dynamic DNA binding licenses a repair factor to bypass roadblocks in search of DNA lesions. Nat Commun 2016; 7:10607. [PMID: 26837705 PMCID: PMC4742970 DOI: 10.1038/ncomms10607] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 01/04/2016] [Indexed: 12/17/2022] Open
Abstract
DNA-binding proteins search for specific targets via facilitated diffusion along a crowded genome. However, little is known about how crowded DNA modulates facilitated diffusion and target recognition. Here we use DNA curtains and single-molecule fluorescence imaging to investigate how Msh2-Msh3, a eukaryotic mismatch repair complex, navigates on crowded DNA. Msh2-Msh3 hops over nucleosomes and other protein roadblocks, but maintains sufficient contact with DNA to recognize a single lesion. In contrast, Msh2-Msh6 slides without hopping and is largely blocked by protein roadblocks. Remarkably, the Msh3-specific mispair-binding domain (MBD) licences a chimeric Msh2-Msh6(3MBD) to bypass nucleosomes. Our studies contrast how Msh2-Msh3 and Msh2-Msh6 navigate on a crowded genome and suggest how Msh2-Msh3 locates DNA lesions outside of replication-coupled repair. These results also provide insights into how DNA repair factors search for DNA lesions in the context of chromatin.
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Affiliation(s)
- Maxwell W Brown
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Yoori Kim
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Gregory M Williams
- Department of Biochemistry, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York 14214, USA
| | - John D Huck
- Department of Biochemistry, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York 14214, USA
| | - Jennifer A Surtees
- Department of Biochemistry, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York 14214, USA
| | - Ilya J Finkelstein
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.,Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas 78712, USA
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22
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Hingorani MM. Mismatch binding, ADP-ATP exchange and intramolecular signaling during mismatch repair. DNA Repair (Amst) 2016; 38:24-31. [PMID: 26704427 PMCID: PMC4740199 DOI: 10.1016/j.dnarep.2015.11.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Revised: 09/08/2015] [Accepted: 11/30/2015] [Indexed: 12/16/2022]
Abstract
The focus of this article is on the DNA binding and ATPase activities of the mismatch repair (MMR) protein, MutS-our current understanding of how this protein uses ATP to fuel its actions on DNA and initiate repair via interactions with MutL, the next protein in the pathway. Structure-function and kinetic studies have yielded detailed views of the MutS mechanism of action in MMR. How MutS and MutL work together after mismatch recognition to enable strand-specific nicking, which leads to strand excision and synthesis, is less clear and remains an active area of investigation.
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23
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Kolodner RD. A personal historical view of DNA mismatch repair with an emphasis on eukaryotic DNA mismatch repair. DNA Repair (Amst) 2016; 38:3-13. [PMID: 26698650 PMCID: PMC4740188 DOI: 10.1016/j.dnarep.2015.11.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 10/30/2015] [Accepted: 11/30/2015] [Indexed: 01/12/2023]
Affiliation(s)
- Richard D Kolodner
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, Moores-UCSD Cancer Center and Institute for Molecular Medicine, University of CA, San Diego School of Medicine, La Jolla, CA 92093-0669, United States.
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24
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Manhart CM, Alani E. Roles for mismatch repair family proteins in promoting meiotic crossing over. DNA Repair (Amst) 2016; 38:84-93. [PMID: 26686657 PMCID: PMC4740264 DOI: 10.1016/j.dnarep.2015.11.024] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 08/14/2015] [Accepted: 11/30/2015] [Indexed: 12/13/2022]
Abstract
The mismatch repair (MMR) family complexes Msh4-Msh5 and Mlh1-Mlh3 act with Exo1 and Sgs1-Top3-Rmi1 in a meiotic double strand break repair pathway that results in the asymmetric cleavage of double Holliday junctions (dHJ) to form crossovers. This review discusses how meiotic roles for Msh4-Msh5 and Mlh1-Mlh3 do not fit paradigms established for post-replicative MMR. We also outline models used to explain how these factors promote the formation of meiotic crossovers required for the accurate segregation of chromosome homologs during the Meiosis I division.
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Affiliation(s)
- Carol M Manhart
- Department of Molecular Biology and Genetics, Cornell University, 457 Biotechnology Building, Ithaca, NY 14853-2703, USA
| | - Eric Alani
- Department of Molecular Biology and Genetics, Cornell University, 457 Biotechnology Building, Ithaca, NY 14853-2703, USA.
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25
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Patil S, Moeys S, von Dassow P, Huysman MJJ, Mapleson D, De Veylder L, Sanges R, Vyverman W, Montresor M, Ferrante MI. Identification of the meiotic toolkit in diatoms and exploration of meiosis-specific SPO11 and RAD51 homologs in the sexual species Pseudo-nitzschia multistriata and Seminavis robusta. BMC Genomics 2015; 16:930. [PMID: 26572248 PMCID: PMC4647503 DOI: 10.1186/s12864-015-1983-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 10/04/2015] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Sexual reproduction is an obligate phase in the life cycle of most eukaryotes. Meiosis varies among organisms, which is reflected by the variability of the gene set associated to the process. Diatoms are unicellular organisms that belong to the stramenopile clade and have unique life cycles that can include a sexual phase. RESULTS The exploration of five diatom genomes and one diatom transcriptome led to the identification of 42 genes potentially involved in meiosis. While these include the majority of known meiosis-related genes, several meiosis-specific genes, including DMC1, could not be identified. Furthermore, phylogenetic analyses supported gene identification and revealed ancestral loss and recent expansion in the RAD51 family in diatoms. The two sexual species Pseudo-nitzschia multistriata and Seminavis robusta were used to explore the expression of meiosis-related genes: RAD21, SPO11-2, RAD51-A, RAD51-B and RAD51-C were upregulated during meiosis, whereas other paralogs in these families showed no differential expression patterns, suggesting that they may play a role during vegetative divisions. An almost identical toolkit is shared among Pseudo-nitzschia multiseries and Fragilariopsis cylindrus, as well as two species for which sex has not been observed, Phaeodactylum tricornutum and Thalassiosira pseudonana, suggesting that these two may retain a facultative sexual phase. CONCLUSIONS Our results reveal the conserved meiotic toolkit in six diatom species and indicate that Stramenopiles share major modifications of canonical meiosis processes ancestral to eukaryotes, with important divergences in each Kingdom.
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Affiliation(s)
- Shrikant Patil
- Stazione Zoologica Anton Dohrn, Villa Comunale 1, 80121, Naples, Italy.
| | - Sara Moeys
- Department of Biology, Protistology and Aquatic Ecology, Ghent University, 9000, Ghent, Belgium. .,Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), 9052, Ghent, Belgium. .,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium.
| | - Peter von Dassow
- Facultad de Ciencias Biológicas, Instituto Milenio de Oceanografía, Pontificia Universidad Católica de Chile, Santiago, Chile. .,UMI 3614, Evolutionary Biology and Ecology of Algae, CNRS-UPMC Sorbonne Universités, PUCCh, UACH, Station Biologique de Roscoff, Roscoff, France.
| | - Marie J J Huysman
- Department of Biology, Protistology and Aquatic Ecology, Ghent University, 9000, Ghent, Belgium. .,Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), 9052, Ghent, Belgium. .,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium.
| | - Daniel Mapleson
- The Genome Analysis Centre (TGAC), Norwich Research Park, Norwich, NR4 7UH, UK.
| | - Lieven De Veylder
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), 9052, Ghent, Belgium. .,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium.
| | - Remo Sanges
- Stazione Zoologica Anton Dohrn, Villa Comunale 1, 80121, Naples, Italy.
| | - Wim Vyverman
- Department of Biology, Protistology and Aquatic Ecology, Ghent University, 9000, Ghent, Belgium.
| | - Marina Montresor
- Stazione Zoologica Anton Dohrn, Villa Comunale 1, 80121, Naples, Italy.
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26
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Abstract
DNA mismatch repair (MMR) identifies and corrects errors made during replication. In all organisms except those expressing MutH, interactions between a DNA mismatch, MutS, MutL, and the replication processivity factor (β-clamp or PCNA) activate the latent MutL endonuclease to nick the error-containing daughter strand. This nick provides an entry point for downstream repair proteins. Despite the well-established significance of strand-specific nicking in MMR, the mechanism(s) by which MutS and MutL assemble on mismatch DNA to allow the subsequent activation of MutL's endonuclease activity by β-clamp/PCNA remains elusive. In both prokaryotes and eukaryotes, MutS homologs undergo conformational changes to a mobile clamp state that can move away from the mismatch. However, the function of this MutS mobile clamp is unknown. Furthermore, whether the interaction with MutL leads to a mobile MutS-MutL complex or a mismatch-localized complex is hotly debated. We used single molecule FRET to determine that Thermus aquaticus MutL traps MutS at a DNA mismatch after recognition but before its conversion to a sliding clamp. Rather than a clamp, a conformationally dynamic protein assembly typically containing more MutL than MutS is formed at the mismatch. This complex provides a local marker where interaction with β-clamp/PCNA could distinguish parent/daughter strand identity. Our finding that MutL fundamentally changes MutS actions following mismatch detection reframes current thinking on MMR signaling processes critical for genomic stability.
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27
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Smith CE, Bowen N, Graham WJ, Goellner EM, Srivatsan A, Kolodner RD. Activation of Saccharomyces cerevisiae Mlh1-Pms1 Endonuclease in a Reconstituted Mismatch Repair System. J Biol Chem 2015; 290:21580-90. [PMID: 26170454 PMCID: PMC4571882 DOI: 10.1074/jbc.m115.662189] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Indexed: 11/07/2022] Open
Abstract
Previous studies reported the reconstitution of an Mlh1-Pms1-independent 5′ nick-directed mismatch repair (MMR) reaction using Saccharomyces cerevisiae proteins. Here we describe the reconstitution of a mispair-dependent Mlh1-Pms1 endonuclease activation reaction requiring Msh2-Msh6 (or Msh2-Msh3), proliferating cell nuclear antigen (PCNA), and replication factor C (RFC) and a reconstituted Mlh1-Pms1-dependent 3′ nick-directed MMR reaction requiring Msh2-Msh6 (or Msh2-Msh3), exonuclease 1 (Exo1), replication protein A (RPA), RFC, PCNA, and DNA polymerase δ. Both reactions required Mg2+ and Mn2+ for optimal activity. The MMR reaction also required two reaction stages in which the first stage required incubation of Mlh1-Pms1 with substrate DNA, with or without Msh2-Msh6 (or Msh2-Msh3), PCNA, and RFC but did not require nicking of the substrate, followed by a second stage in which other proteins were added. Analysis of different mutant proteins demonstrated that both reactions required a functional Mlh1-Pms1 endonuclease active site, as well as mispair recognition and Mlh1-Pms1 recruitment by Msh2-Msh6 but not sliding clamp formation. Mutant Mlh1-Pms1 and PCNA proteins that were defective for Exo1-independent but not Exo1-dependent MMR in vivo were partially defective in the Mlh1-Pms1 endonuclease and MMR reactions, suggesting that both reactions reflect the activation of Mlh1-Pms1 seen in Exo1-independent MMR in vivo. The availability of this reconstituted MMR reaction should now make it possible to better study both Exo1-independent and Exo1-dependent MMR.
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Affiliation(s)
| | - Nikki Bowen
- From the Ludwig Institute for Cancer Research
| | | | | | | | - Richard D Kolodner
- From the Ludwig Institute for Cancer Research, the Department of Cellular and Molecular Medicine, Moores-UCSD Cancer Center, and the Institute of Genomic Medicine, University of California, San Diego School of Medicine, La Jolla, California 92093
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28
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Goellner EM, Putnam CD, Kolodner RD. Exonuclease 1-dependent and independent mismatch repair. DNA Repair (Amst) 2015; 32:24-32. [PMID: 25956862 DOI: 10.1016/j.dnarep.2015.04.010] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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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29
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Reyes GX, Schmidt TT, Kolodner RD, Hombauer H. New insights into the mechanism of DNA mismatch repair. Chromosoma 2015; 124:443-62. [PMID: 25862369 DOI: 10.1007/s00412-015-0514-0] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Revised: 03/23/2015] [Accepted: 03/23/2015] [Indexed: 12/20/2022]
Abstract
The genome of all organisms is constantly being challenged by endogenous and exogenous sources of DNA damage. Errors like base:base mismatches or small insertions and deletions, primarily introduced by DNA polymerases during DNA replication are repaired by an evolutionary conserved DNA mismatch repair (MMR) system. The MMR system, together with the DNA replication machinery, promote repair by an excision and resynthesis mechanism during or after DNA replication, increasing replication fidelity by up-to-three orders of magnitude. Consequently, inactivation of MMR genes results in elevated mutation rates that can lead to increased cancer susceptibility in humans. In this review, we summarize our current understanding of MMR with a focus on the different MMR protein complexes, their function and structure. We also discuss how recent findings have provided new insights in the spatio-temporal regulation and mechanism of MMR.
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Affiliation(s)
- Gloria X Reyes
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 581, 69120, Heidelberg, Germany
| | - Tobias T Schmidt
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 581, 69120, Heidelberg, Germany
| | - Richard D Kolodner
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, Moores-UCSD Cancer Center and Institute of Genomic Medicine, University of California, San Diego School of Medicine, 9500 Gilman Drive, La Jolla, CA, 92093-0669, USA
| | - Hans Hombauer
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 581, 69120, Heidelberg, Germany.
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30
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Abstract
Three processes act in series to accurately replicate the eukaryotic nuclear genome. The major replicative DNA polymerases strongly prevent mismatch formation, occasional mismatches that do form are proofread during replication, and rare mismatches that escape proofreading are corrected by mismatch repair (MMR). This review focuses on MMR in light of increasing knowledge about nuclear DNA replication enzymology and the rate and specificity with which mismatches are generated during leading- and lagging-strand replication. We consider differences in MMR efficiency in relation to mismatch recognition, signaling to direct MMR to the nascent strand, mismatch removal, and the timing of MMR. These studies are refining our understanding of relationships between generating and repairing replication errors to achieve accurate replication of both DNA strands of the nuclear genome.
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Affiliation(s)
- Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina 27709;
| | - Dorothy A Erie
- Department of Chemistry and Curriculum in Applied Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599-3290;
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31
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Velho S, Fernandes MS, Leite M, Figueiredo C, Seruca R. Causes and consequences of microsatellite instability in gastric carcinogenesis. World J Gastroenterol 2014; 20:16433-16442. [PMID: 25469011 PMCID: PMC4248186 DOI: 10.3748/wjg.v20.i44.16433] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/24/2014] [Accepted: 09/05/2014] [Indexed: 02/06/2023] Open
Abstract
Loss of DNA mismatch repair (MMR) function, due to somatic or germline epi/genetic alterations of MMR genes leads to the accumulation of numerous mutations across the genome, creating a molecular phenotype known as microsatellite instability (MSI). In gastric cancer (GC), MSI occurs in about 15% to 30% of the cases. This review summarizes the current knowledge on the molecular mechanisms underlying the acquisition of MSI in GC as well as on the clinic, pathologic and molecular consequences of the MSI phenotype. Additionally, current therapeutic strategies for GC and their applicability in the MSI subset are also discussed.
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32
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Tosti E, Katakowski JA, Schaetzlein S, Kim HS, Ryan CJ, Shales M, Roguev A, Krogan NJ, Palliser D, Keogh MC, Edelmann W. Evolutionarily conserved genetic interactions with budding and fission yeast MutS identify orthologous relationships in mismatch repair-deficient cancer cells. Genome Med 2014; 6:68. [PMID: 25302077 PMCID: PMC4189729 DOI: 10.1186/s13073-014-0068-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 08/28/2014] [Indexed: 12/13/2022] Open
Abstract
Background The evolutionarily conserved DNA mismatch repair (MMR) system corrects base-substitution and insertion-deletion mutations generated during erroneous replication. The mutation or inactivation of many MMR factors strongly predisposes to cancer, where the resulting tumors often display resistance to standard chemotherapeutics. A new direction to develop targeted therapies is the harnessing of synthetic genetic interactions, where the simultaneous loss of two otherwise non-essential factors leads to reduced cell fitness or death. High-throughput screening in human cells to directly identify such interactors for disease-relevant genes is now widespread, but often requires extensive case-by-case optimization. Here we asked if conserved genetic interactors (CGIs) with MMR genes from two evolutionary distant yeast species (Saccharomyces cerevisiae and Schizosaccharomyzes pombe) can predict orthologous genetic relationships in higher eukaryotes. Methods High-throughput screening was used to identify genetic interaction profiles for the MutSα and MutSβ heterodimer subunits (msh2Δ, msh3Δ, msh6Δ) of fission yeast. Selected negative interactors with MutSβ (msh2Δ/msh3Δ) were directly analyzed in budding yeast, and the CGI with SUMO-protease Ulp2 further examined after RNA interference/drug treatment in MSH2-deficient and -proficient human cells. Results This study identified distinct genetic profiles for MutSα and MutSβ, and supports a role for the latter in recombinatorial DNA repair. Approximately 28% of orthologous genetic interactions with msh2Δ/msh3Δ are conserved in both yeasts, a degree consistent with global trends across these species. Further, the CGI between budding/fission yeast msh2 and SUMO-protease Ulp2 is maintained in human cells (MSH2/SENP6), and enhanced by Olaparib, a PARP inhibitor that induces the accumulation of single-strand DNA breaks. This identifies SENP6 as a promising new target for the treatment of MMR-deficient cancers. Conclusion Our findings demonstrate the utility of employing evolutionary distance in tractable lower eukaryotes to predict orthologous genetic relationships in higher eukaryotes. Moreover, we provide novel insights into the genome maintenance functions of a critical DNA repair complex and propose a promising targeted treatment for MMR deficient tumors. Electronic supplementary material The online version of this article (doi:10.1186/s13073-014-0068-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Elena Tosti
- Department of Cell Biology, Albert Einstein College of Medicine, New York, USA
| | - Joseph A Katakowski
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, New York, USA
| | - Sonja Schaetzlein
- Department of Cell Biology, Albert Einstein College of Medicine, New York, USA
| | - Hyun-Soo Kim
- Department of Cell Biology, Albert Einstein College of Medicine, New York, USA
| | - Colm J Ryan
- Department of Cellular & Molecular Pharmacology, UCSF, San Francisco, USA ; California Institute for Quantitative Biosciences, San Francisco, USA ; School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Michael Shales
- Department of Cellular & Molecular Pharmacology, UCSF, San Francisco, USA
| | - Assen Roguev
- Department of Cellular & Molecular Pharmacology, UCSF, San Francisco, USA
| | - Nevan J Krogan
- Department of Cellular & Molecular Pharmacology, UCSF, San Francisco, USA ; California Institute for Quantitative Biosciences, San Francisco, USA ; J. David Gladstone Institutes, San Francisco, USA
| | - Deborah Palliser
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, New York, USA
| | | | - Winfried Edelmann
- Department of Cell Biology, Albert Einstein College of Medicine, New York, USA
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33
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Goellner EM, Smith CE, Campbell CS, Hombauer H, Desai A, Putnam CD, Kolodner RD. PCNA and Msh2-Msh6 activate an Mlh1-Pms1 endonuclease pathway required for Exo1-independent mismatch repair. Mol Cell 2014; 55:291-304. [PMID: 24981171 DOI: 10.1016/j.molcel.2014.04.034] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/09/2014] [Accepted: 04/28/2014] [Indexed: 11/17/2022]
Abstract
Genetic evidence has implicated multiple pathways in eukaryotic DNA mismatch repair (MMR) downstream of mispair recognition and Mlh1-Pms1 recruitment, including Exonuclease 1 (Exo1)-dependent and -independent pathways. We identified 14 mutations in POL30, which encodes PCNA in Saccharomyces cerevisiae, specific to Exo1-independent MMR. The mutations identified affected amino acids at three distinct sites on the PCNA structure. Multiple mutant PCNA proteins had defects either in trimerization and Msh2-Msh6 binding or in activation of the Mlh1-Pms1 endonuclease that initiates excision during MMR. The latter class of mutations led to hyperaccumulation of repair intermediate Mlh1-Pms1 foci and were enhanced by an msh6 mutation that disrupted the Msh2-Msh6 interaction with PCNA. These results reveal a central role for PCNA in the Exo1-independent MMR pathway and suggest that Msh2-Msh6 localizes PCNA to repair sites after mispair recognition to activate the Mlh1-Pms1 endonuclease for initiating Exo1-dependent repair or for driving progressive excision in Exo1-independent repair.
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Affiliation(s)
- Eva M Goellner
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA
| | - Catherine E Smith
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA
| | - Christopher S Campbell
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA
| | - Hans Hombauer
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Arshad Desai
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Cellular and Molecular Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA
| | - Christopher D Putnam
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA
| | - Richard D Kolodner
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Cellular and Molecular Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Moores-UCSD Cancer Center, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Institute of Genomic Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA.
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Campbell CS, Hombauer H, Srivatsan A, Bowen N, Gries K, Desai A, Putnam CD, Kolodner RD. Mlh2 is an accessory factor for DNA mismatch repair in Saccharomyces cerevisiae. PLoS Genet 2014; 10:e1004327. [PMID: 24811092 PMCID: PMC4014439 DOI: 10.1371/journal.pgen.1004327] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 03/10/2014] [Indexed: 12/30/2022] Open
Abstract
In Saccharomyces cerevisiae, the essential mismatch repair (MMR) endonuclease Mlh1-Pms1 forms foci promoted by Msh2-Msh6 or Msh2-Msh3 in response to mispaired bases. Here we analyzed the Mlh1-Mlh2 complex, whose role in MMR has been unclear. Mlh1-Mlh2 formed foci that often colocalized with and had a longer lifetime than Mlh1-Pms1 foci. Mlh1-Mlh2 foci were similar to Mlh1-Pms1 foci: they required mispair recognition by Msh2-Msh6, increased in response to increased mispairs or downstream defects in MMR, and formed after induction of DNA damage by phleomycin but not double-stranded breaks by I-SceI. Mlh1-Mlh2 could be recruited to mispair-containing DNA in vitro by either Msh2-Msh6 or Msh2-Msh3. Deletion of MLH2 caused a synergistic increase in mutation rate in combination with deletion of MSH6 or reduced expression of Pms1. Phylogenetic analysis demonstrated that the S. cerevisiae Mlh2 protein and the mammalian PMS1 protein are homologs. These results support a hypothesis that Mlh1-Mlh2 is a non-essential accessory factor that acts to enhance the activity of Mlh1-Pms1. Lynch syndrome (hereditary nonpolyposis colorectal cancer or HNPCC) is a common cancer predisposition syndrome. In this syndrome, predisposition to cancer results from increased accumulation of mutations due to defective mismatch repair (MMR) caused by a mutation in one of the human mismatch repair genes MLH1, MSH2, MSH6 or PMS2. In addition to these genes, various DNA replication factors and the excision factor EXO1 function in the repair of damaged DNA by the MMR pathway. In Saccharomyces cerevisiae, the MLH2 gene encodes a MutL homolog protein whose role in DNA mismatch repair has been unclear. Here, we used phylogenetic analysis to demonstrate that the S. cerevisiae Mlh2 protein and the mammalian Pms1 protein are homologs. A combination of genetics, biochemistry and imaging studies were used to demonstrate that the Mlh1-Mlh2 complex is recruited to mispair-containing DNA by the Msh2-Msh6 and Msh2-Msh3 mispair recognition complexes where it forms foci that colocalize with Mlh1-Pms1 foci (note that scPms1 is the homolog of hPms2) and augments the function of the Mlh1-Pms1 complex. Thus, this work establishes the Mlh1-Mlh2 complex as a non-essential accessory factor that functions in MMR.
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Affiliation(s)
- Christopher S. Campbell
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
| | - Hans Hombauer
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 581, Heidelberg, Germany
| | - Anjana Srivatsan
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
| | - Nikki Bowen
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
| | - Kerstin Gries
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 581, Heidelberg, Germany
| | - Arshad Desai
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- Department of Cellular and Molecular Medicine, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- Moores-UCSD Cancer Center, University of California School of Medicine, San Diego, La Jolla, California, United States of America
| | - Christopher D. Putnam
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- Department of Medicine, University of California School of Medicine, San Diego, La Jolla, California, United States of America
| | - Richard D. Kolodner
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- Department of Cellular and Molecular Medicine, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- Moores-UCSD Cancer Center, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- Department of Medicine, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- * E-mail:
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