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Mao C, Li S, Che J, Liu D, Mao X, Rao H. The ubiquitin ligase UBR4 and the deubiquitylase USP5 modulate the stability of DNA mismatch repair protein MLH1. J Biol Chem 2024; 300:107592. [PMID: 39032648 PMCID: PMC11375253 DOI: 10.1016/j.jbc.2024.107592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 06/29/2024] [Accepted: 07/10/2024] [Indexed: 07/23/2024] Open
Abstract
MLH1 plays a critical role in DNA mismatch repair and genome maintenance. MLH1 deficiency promotes cancer development and progression, but the mechanism underlying MLH1 regulation remains enigmatic. In this study, we demonstrated that MLH1 protein is degraded by the ubiquitin-proteasome system and have identified vital cis-elements and trans-factors involved in MLH1 turnover. We found that the region encompassing the amino acids 516 to 650 is crucial for MLH1 degradation. The mismatch repair protein PMS2 may shield MLH1 from degradation as it binds to the MLH1 segment key to its turnover. Furthermore, we have identified the E3 ubiquitin ligase UBR4 and the deubiquitylase USP5, which oppositely modulate MLH1 stability. In consistence, UBR4 or USP5 deficiency affects the cellular response to nucleotide analog 6-TG, supporting their roles in regulating mismatch repair. Our study has revealed important insights into the regulatory mechanisms underlying MLH1 proteolysis, critical to DNA mismatch repair related diseases.
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Affiliation(s)
- Chenyu Mao
- Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen, China
| | - Siqi Li
- Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen, China
| | - Jun Che
- Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen, China
| | - Dongzhou Liu
- Department of Rheumatology and Immunology, Shenzhen People's Hospital, Shenzhen, Guangdong, China; The First Affiliated Hospital, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Xinliang Mao
- Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong, China.
| | - Hai Rao
- Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen, China; Key University Laboratory of Metabolism and Health of Guangdong, Southern University of Science and Technology, Shenzhen, China.
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2
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Chatterjee T, Tiwari A, Gupta R, Shukla H, Varshney A, Mishra S, Habib S. A Plasmodium apicoplast-targeted unique exonuclease/FEN exhibits interspecies functional differences attributable to an insertion that alters DNA-binding. Nucleic Acids Res 2024; 52:7843-7862. [PMID: 38888125 PMCID: PMC11260460 DOI: 10.1093/nar/gkae512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 05/30/2024] [Accepted: 06/03/2024] [Indexed: 06/20/2024] Open
Abstract
The human malaria parasite Plasmodium falciparum genome is among the most A + T rich, with low complexity regions (LCRs) inserted in coding sequences including those for proteins targeted to its essential relict plastid (apicoplast). Replication of the apicoplast genome (plDNA), mediated by the atypical multifunctional DNA polymerase PfPrex, would require additional enzymatic functions for lagging strand processing. We identified an apicoplast-targeted, [4Fe-4S]-containing, FEN/Exo (PfExo) with a long LCR insertion and detected its interaction with PfPrex. Distinct from other known exonucleases across organisms, PfExo recognized a wide substrate range; it hydrolyzed 5'-flaps, processed dsDNA as a 5'-3' exonuclease, and was a bipolar nuclease on ssDNA and RNA-DNA hybrids. Comparison with the rodent P. berghei ortholog PbExo, which lacked the insertion and [4Fe-4S], revealed interspecies functional differences. The insertion-deleted PfExoΔins behaved like PbExo with a limited substrate repertoire because of compromised DNA binding. Introduction of the PfExo insertion into PbExo led to gain of activities that the latter initially lacked. Knockout of PbExo indicated essentiality of the enzyme for survival. Our results demonstrate the presence of a novel apicoplast exonuclease with a functional LCR that diversifies substrate recognition, and identify it as the candidate flap-endonuclease and RNaseH required for plDNA replication and maintenance.
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Affiliation(s)
- Tribeni Chatterjee
- Division of Biochemistry and Structural Biology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Anupama Tiwari
- Division of Biochemistry and Structural Biology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Ritika Gupta
- Division of Biochemistry and Structural Biology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Himadri Shukla
- Division of Molecular Microbiology and Immunology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Aastha Varshney
- Division of Molecular Microbiology and Immunology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Satish Mishra
- Division of Molecular Microbiology and Immunology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Saman Habib
- Division of Biochemistry and Structural Biology, CSIR-Central Drug Research Institute, Lucknow, India
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3
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Oh JM, Kang Y, Park J, Sung Y, Kim D, Seo Y, Lee E, Ra J, Amarsanaa E, Park YU, Lee S, Hwang J, Kim H, Schärer O, Cho S, Lee C, Takata KI, Lee J, Myung K. MSH2-MSH3 promotes DNA end resection during homologous recombination and blocks polymerase theta-mediated end-joining through interaction with SMARCAD1 and EXO1. Nucleic Acids Res 2023; 51:5584-5602. [PMID: 37140056 PMCID: PMC10287916 DOI: 10.1093/nar/gkad308] [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: 08/16/2022] [Revised: 04/04/2023] [Accepted: 04/27/2023] [Indexed: 05/05/2023] Open
Abstract
DNA double-strand break (DSB) repair via homologous recombination is initiated by end resection. The extent of DNA end resection determines the choice of the DSB repair pathway. Nucleases for end resection have been extensively studied. However, it is still unclear how the potential DNA structures generated by the initial short resection by MRE11-RAD50-NBS1 are recognized and recruit proteins, such as EXO1, to DSB sites to facilitate long-range resection. We found that the MSH2-MSH3 mismatch repair complex is recruited to DSB sites through interaction with the chromatin remodeling protein SMARCAD1. MSH2-MSH3 facilitates the recruitment of EXO1 for long-range resection and enhances its enzymatic activity. MSH2-MSH3 also inhibits access of POLθ, which promotes polymerase theta-mediated end-joining (TMEJ). Collectively, we present a direct role of MSH2-MSH3 in the initial stages of DSB repair by promoting end resection and influencing the DSB repair pathway by favoring homologous recombination over TMEJ.
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Affiliation(s)
- Jung-Min Oh
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
- Department of Oral Biochemistry, Dental and Life Science Institute, School of Dentistry, Pusan National University, Yangsan 50612, Republic of Korea
| | - Yujin Kang
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan44919, Republic of Korea
| | - Jumi Park
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan44919, Republic of Korea
| | - Yubin Sung
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Dayoung Kim
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan44919, Republic of Korea
| | - Yuri Seo
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Eun A Lee
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Jae Sun Ra
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Enkhzul Amarsanaa
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan44919, Republic of Korea
| | - Young-Un Park
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Seon Young Lee
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Jung Me Hwang
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Hongtae Kim
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan44919, Republic of Korea
| | - Orlando Schärer
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan44919, Republic of Korea
| | - Seung Woo Cho
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan44919, Republic of Korea
| | - Changwook Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan44919, Republic of Korea
| | - Kei-ichi Takata
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan44919, Republic of Korea
| | - Ja Yil Lee
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan44919, Republic of Korea
| | - Kyungjae Myung
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan44919, Republic of Korea
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4
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Oh JM, Myung K. Crosstalk between different DNA repair pathways for DNA double strand break repairs. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2022; 873:503438. [PMID: 35094810 DOI: 10.1016/j.mrgentox.2021.503438] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 11/09/2021] [Accepted: 12/14/2021] [Indexed: 11/28/2022]
Abstract
DNA double strand breaks (DSBs) are the most threatening type of DNA lesions and must be repaired properly in order to inhibit severe diseases and cell death. There are four major repair pathways for DSBs: non-homologous end joining (NHEJ), homologous recombination (HR), single strand annealing (SSA) and alternative end joining (alt-EJ). Cells choose repair pathway depending on the cell cycle phase and the length of 3' end of the DNA when DSBs are generated. Blunt and short regions of the 5' or 3' overhang DNA are repaired by NHEJ, which uses direct ligation or limited resection processing of the broken DNA end. In contrast, HR, SSA and alt-EJ use the resected DNA generated by the MRN (MRE11-RAD50-NBS1) complex and C-terminal binding protein interacting protein (CtIP) activated during the S and G2 phases. Here, we review recent findings on each repair pathway and the choice of repair mechanism and highlight the role of mismatch repair (MMR) protein in HR.
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Affiliation(s)
- Jung-Min Oh
- Department of Oral Biochemistry, Dental and Life Science Institute, School of Dentistry, Pusan National University, Yangsan 50612, Republic of Korea.
| | - Kyungjae Myung
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea; Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea.
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5
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Kratz K, Artola-Borán M, Kobayashi-Era S, Koh G, Oliveira G, Kobayashi S, Oliveira A, Zou X, Richter J, Tsuda M, Sasanuma H, Takeda S, Loizou JI, Sartori AA, Nik-Zainal S, Jiricny J. FANCD2-Associated Nuclease 1 Partially Compensates for the Lack of Exonuclease 1 in Mismatch Repair. Mol Cell Biol 2021; 41:e0030321. [PMID: 34228493 PMCID: PMC8384067 DOI: 10.1128/mcb.00303-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 06/28/2021] [Indexed: 11/20/2022] Open
Abstract
Germline mutations in the mismatch repair (MMR) genes MSH2, MSH6, MLH1, and PMS2 are linked to cancer of the colon and other organs, characterized by microsatellite instability and a large increase in mutation frequency. Unexpectedly, mutations in EXO1, encoding the only exonuclease genetically implicated in MMR, are not linked to familial cancer and cause a substantially weaker mutator phenotype. This difference could be explained if eukaryotic cells possessed additional exonucleases redundant with EXO1. Analysis of the MLH1 interactome identified FANCD2-associated nuclease 1 (FAN1), a novel enzyme with biochemical properties resembling EXO1. We now show that FAN1 efficiently substitutes for EXO1 in MMR assays and that this functional complementation is modulated by its interaction with MLH1. FAN1 also contributes to MMR in vivo; cells lacking both EXO1 and FAN1 have an MMR defect and display resistance to N-methyl-N-nitrosourea (MNU) and 6-thioguanine (TG). Moreover, FAN1 loss amplifies the mutational profile of EXO1-deficient cells, suggesting that the two nucleases act redundantly in the same antimutagenic pathway. However, the increased drug resistance and mutator phenotype of FAN1/EXO1-deficient cells are less prominent than those seen in cells lacking MSH6 or MLH1. Eukaryotic cells thus apparently possess additional mechanisms that compensate for the loss of EXO1.
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Affiliation(s)
- Katja Kratz
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Mariela Artola-Borán
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Saho Kobayashi-Era
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
- Institute of Biochemistry of the ETH Zurich, Zurich, Switzerland
| | - Gene Koh
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
- Academic Department of Medical Genetics, The Clinical School, University of Cambridge, Cambridge, United Kingdom
- MRC Cancer Unit, The Clinical School, University of Cambridge, Cambridge, United Kingdom
| | - Goncalo Oliveira
- Institute of Cancer Research, Department of Medicine I, Comprehensive Cancer Centre, Medical University of Vienna, Vienna, Austria
| | - Shunsuke Kobayashi
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
- Institute of Biochemistry of the ETH Zurich, Zurich, Switzerland
| | - Andreia Oliveira
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
- Institute of Biochemistry of the ETH Zurich, Zurich, Switzerland
| | - Xueqing Zou
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
- Academic Department of Medical Genetics, The Clinical School, University of Cambridge, Cambridge, United Kingdom
- MRC Cancer Unit, The Clinical School, University of Cambridge, Cambridge, United Kingdom
| | - Julia Richter
- Institute of Biochemistry of the ETH Zurich, Zurich, Switzerland
| | - 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
| | - Shunichi Takeda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Joanna I. Loizou
- Institute of Cancer Research, Department of Medicine I, Comprehensive Cancer Centre, Medical University of Vienna, Vienna, Austria
| | | | - Serena Nik-Zainal
- Academic Department of Medical Genetics, The Clinical School, University of Cambridge, Cambridge, United Kingdom
- MRC Cancer Unit, The Clinical School, University of Cambridge, Cambridge, United Kingdom
| | - Josef Jiricny
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
- Institute of Biochemistry of the ETH Zurich, Zurich, Switzerland
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6
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Gillman R, Lopes Floro K, Wankell M, Hebbard L. The role of DNA damage and repair in liver cancer. Biochim Biophys Acta Rev Cancer 2020; 1875:188493. [PMID: 33316376 DOI: 10.1016/j.bbcan.2020.188493] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/25/2020] [Accepted: 12/08/2020] [Indexed: 02/07/2023]
Abstract
Hepatocellular carcinoma is rapidly becoming a major cause of global mortality due to the ever-increasing prevalence of obesity. DNA damage is known to play an important role in cancer initiation, however DNA repair systems are also vital for the survival of cancer cells. Given the function of the liver and its exposure to the gut, it is likely that DNA damage and repair would be of particular importance in hepatocellular carcinoma. However, many contemporary reports have neglected the role of individual pathways of DNA damage and repair in their hypotheses. This review, therefore, aims to provide a concise overview for researchers in the field of liver cancer to understand the pathways of DNA damage and repair and their individual roles in hepatocellular carcinoma.
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Affiliation(s)
- Rhys Gillman
- Department of Molecular and Cell Biology, College of Public Health, Medical, and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia
| | - Kylie Lopes Floro
- Department of Molecular and Cell Biology, College of Public Health, Medical, and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia; Department of Radiation Oncology, Townsville University Hospital, Townsville, Queensland, Australia
| | - Miriam Wankell
- Department of Molecular and Cell Biology, College of Public Health, Medical, and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia; Australian Institute for Tropical Health and Medicine, Townsville, Queensland, Australia
| | - Lionel Hebbard
- Department of Molecular and Cell Biology, College of Public Health, Medical, and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia; Storr Liver Centre, Westmead Institute for Medical Research, Westmead Hospital and University of Sydney, Sydney, New South Wales, Australia; Australian Institute for Tropical Health and Medicine, Townsville, Queensland, Australia.
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7
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Yang G, Dong K, Zhang Z, Zhang E, Liang B, Chen X, Huang Z. EXO1 Plays a Carcinogenic Role in Hepatocellular Carcinoma and is related to the regulation of FOXP3. J Cancer 2020; 11:4917-4932. [PMID: 32626539 PMCID: PMC7330697 DOI: 10.7150/jca.40673] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 05/29/2020] [Indexed: 12/21/2022] Open
Abstract
Exonuclease 1 (EXO1), a member of the RAD2 nuclease family, was first described as possessing 5' to 3' nuclease activity and 5' structure-specific endonuclease activity. Here, we show that EXO1 is significantly upregulated in HCC tumor tissues and that high EXO1 expression is significantly correlated with liver cirrhosis. We further demonstrate that EXO1 knockdown decreases proliferation and colony forming abilities of HCC cells in vitro and tumorigenicity in vivo, as well as decreases migration and invasive capabilities of HCC cells. Alternatively, EXO1 overexpression significantly increases the proliferation, colony forming ability, and migration and invasive capabilities of HCC cells in vitro. Additionally, we truncated a region upstream of the transcription start site (TSS) of EXO1 and used the region with the strongest transcriptional activity to predict that the transcription factor FOXP3 can bind to the EXO1 promoter. Bioinformatics analysis found that FOXP3 was positively correlated with EXO1 and luciferase reporter assays and RT-PCR confirmed that FOXP3 could enhance the transcriptional activity of EXO1. CCK-8 assays showed that depletion of FOXP3 further reduces cell proliferation ability after knocking down of EXO1 in vitro. Taken together, our findings indicate that EXO1 acts as an oncogene in HCC and its expression level is related to FOXP3 activity.
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Affiliation(s)
- Guang Yang
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Keshuai Dong
- Department of Hepatobiliary and Laparoscopic Surgery, Renmin Hospital, Wuhan University, Hubei Key Laboratory of Digestive System Disease, Wuhan, China
| | - Zunyi Zhang
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Erlei Zhang
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Binyong Liang
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoping Chen
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhiyong Huang
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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8
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Rath A, Mishra A, Ferreira VD, Hu C, Omerza G, Kelly K, Hesse A, Reddi HV, Grady JP, Heinen CD. Functional interrogation of Lynch syndrome-associated MSH2 missense variants via CRISPR-Cas9 gene editing in human embryonic stem cells. Hum Mutat 2019; 40:2044-2056. [PMID: 31237724 DOI: 10.1002/humu.23848] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 05/08/2019] [Accepted: 06/19/2019] [Indexed: 12/18/2022]
Abstract
Lynch syndrome (LS) predisposes patients to cancer and is caused by germline mutations in the DNA mismatch repair (MMR) genes. Identifying the deleterious mutation, such as a frameshift or nonsense mutation, is important for confirming an LS diagnosis. However, discovery of a missense variant is often inconclusive. The effects of these variants of uncertain significance (VUS) on disease pathogenesis are unclear, though understanding their impact on protein function can help determine their significance. Laboratory functional studies performed to date have been limited by their artificial nature. We report here an in-cellulo functional assay in which we engineered site-specific MSH2 VUS using clustered regularly interspaced short palindromic repeats-Cas9 gene editing in human embryonic stem cells. This approach introduces the variant into the endogenous MSH2 loci, while simultaneously eliminating the wild-type gene. We characterized the impact of the variants on cellular MMR functions including DNA damage response signaling and the repair of DNA microsatellites. We classified the MMR functional capability of eight of 10 VUS providing valuable information for determining their likelihood of being bona fide pathogenic LS variants. This human cell-based assay system for functional testing of MMR gene VUS will facilitate the identification of high-risk LS patients.
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Affiliation(s)
- Abhijit Rath
- Center for Molecular Oncology and Institute for Systems Genomics, UConn Health, Farmington, Connecticut
| | - Akriti Mishra
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut
| | | | - Chaoran Hu
- Department of Statistics, University of Connecticut, Storrs, Connecticut.,Connecticut Institute for Clinical and Translational Science, UConn Health, Farmington, Connecticut
| | - Gregory Omerza
- Clinical Genomics Laboratory, The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut
| | - Kevin Kelly
- Clinical Genomics Laboratory, The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut
| | - Andrew Hesse
- Clinical Genomics Laboratory, The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut
| | - Honey V Reddi
- Clinical Genomics Laboratory, The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut
| | - James P Grady
- Connecticut Institute for Clinical and Translational Science, UConn Health, Farmington, Connecticut
| | - Christopher D Heinen
- Center for Molecular Oncology and Institute for Systems Genomics, UConn Health, Farmington, Connecticut
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9
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Flower M, Lomeikaite V, Ciosi M, Cumming S, Morales F, Lo K, Hensman Moss D, Jones L, Holmans P, Monckton DG, Tabrizi SJ. MSH3 modifies somatic instability and disease severity in Huntington's and myotonic dystrophy type 1. Brain 2019; 142:awz115. [PMID: 31216018 PMCID: PMC6598626 DOI: 10.1093/brain/awz115] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/31/2019] [Accepted: 02/27/2019] [Indexed: 12/22/2022] Open
Abstract
The mismatch repair gene MSH3 has been implicated as a genetic modifier of the CAG·CTG repeat expansion disorders Huntington's disease and myotonic dystrophy type 1. A recent Huntington's disease genome-wide association study found rs557874766, an imputed single nucleotide polymorphism located within a polymorphic 9 bp tandem repeat in MSH3/DHFR, as the variant most significantly associated with progression in Huntington's disease. Using Illumina sequencing in Huntington's disease and myotonic dystrophy type 1 subjects, we show that rs557874766 is an alignment artefact, the minor allele for which corresponds to a three-repeat allele in MSH3 exon 1 that is associated with a reduced rate of somatic CAG·CTG expansion (P = 0.004) and delayed disease onset (P = 0.003) in both Huntington's disease and myotonic dystrophy type 1, and slower progression (P = 3.86 × 10-7) in Huntington's disease. RNA-Seq of whole blood in the Huntington's disease subjects found that repeat variants are associated with MSH3 and DHFR expression. A transcriptome-wide association study in the Huntington's disease cohort found increased MSH3 and DHFR expression are associated with disease progression. These results suggest that variation in the MSH3 exon 1 repeat region influences somatic expansion and disease phenotype in Huntington's disease and myotonic dystrophy type 1, and suggests a common DNA repair mechanism operates in both repeat expansion diseases.
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Affiliation(s)
- Michael Flower
- Department of Neurodegenerative Disease and Dementia Research Institute, UCL, UK
| | - Vilija Lomeikaite
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, UK
| | - Marc Ciosi
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, UK
| | - Sarah Cumming
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, UK
| | - Fernando Morales
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, UK
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, San José, Costa Rica
| | - Kitty Lo
- School of Mathematics and Statistics, University of Sydney, Australia
| | - Davina Hensman Moss
- Department of Neurodegenerative Disease and Dementia Research Institute, UCL, UK
| | - Lesley Jones
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, UK
| | - Peter Holmans
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, UK
| | - Darren G Monckton
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, UK
| | - Sarah J Tabrizi
- Department of Neurodegenerative Disease and Dementia Research Institute, UCL, UK
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10
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Human Exonuclease 1 (EXO1) Regulatory Functions in DNA Replication with Putative Roles in Cancer. Int J Mol Sci 2018; 20:ijms20010074. [PMID: 30585186 PMCID: PMC6337416 DOI: 10.3390/ijms20010074] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 12/12/2018] [Accepted: 12/19/2018] [Indexed: 12/11/2022] Open
Abstract
Human exonuclease 1 (EXO1), a 5'→3' exonuclease, contributes to the regulation of the cell cycle checkpoints, replication fork maintenance, and post replicative DNA repair pathways. These processes are required for the resolution of stalled or blocked DNA replication that can lead to replication stress and potential collapse of the replication fork. Failure to restart the DNA replication process can result in double-strand breaks, cell-cycle arrest, cell death, or cellular transformation. In this review, we summarize the involvement of EXO1 in the replication, DNA repair pathways, cell cycle checkpoints, and the link between EXO1 and cancer.
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11
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Kim D, Fishel R, Lee JB. Coordinating Multi-Protein Mismatch Repair by Managing Diffusion Mechanics on the DNA. J Mol Biol 2018; 430:4469-4480. [PMID: 29792877 PMCID: PMC6388638 DOI: 10.1016/j.jmb.2018.05.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 05/01/2018] [Accepted: 05/16/2018] [Indexed: 12/15/2022]
Abstract
DNA mismatch repair (MMR) corrects DNA base-pairing errors that occur during DNA replication. MMR catalyzes strand-specific DNA degradation and resynthesis by dynamic molecular coordination of sequential downstream pathways. The temporal and mechanistic order of molecular events is essential to insure interactions in MMR that occur over long distances on the DNA. Biophysical real-time studies of highly conserved components on mismatched DNA have shed light on the mechanics of MMR. Single-molecule imaging has visualized stochastically coordinated MMR interactions that are based on thermal fluctuation-driven motions. In this review, we describe the role of diffusivity and stochasticity in MMR beginning with mismatch recognition through strand-specific excision. We conclude with a perspective of the possible research directions that should solve the remaining questions in MMR.
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Affiliation(s)
- Daehyung Kim
- Department of Physics, Pohang University of Science & Technology (POSTECH), Pohang 37673, Korea
| | - Richard Fishel
- Department of Cancer Biology and Genetics, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA.
| | - Jong-Bong Lee
- Department of Physics, Pohang University of Science & Technology (POSTECH), Pohang 37673, Korea; Interdisciplinary Bioscience & Bioengineering, POSTECH, Pohang 37673, Korea.
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12
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Liu J, Lee JB, Fishel R. Stochastic Processes and Component Plasticity Governing DNA Mismatch Repair. J Mol Biol 2018; 430:4456-4468. [PMID: 29864444 PMCID: PMC6461355 DOI: 10.1016/j.jmb.2018.05.039] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 05/09/2018] [Accepted: 05/28/2018] [Indexed: 02/06/2023]
Abstract
DNA mismatch repair (MMR) is a DNA excision-resynthesis process that principally enhances replication fidelity. Highly conserved MutS (MSH) and MutL (MLH/PMS) homologs initiate MMR and in higher eukaryotes act as DNA damage sensors that can trigger apoptosis. MSH proteins recognize mismatched nucleotides, whereas the MLH/PMS proteins mediate multiple interactions associated with downstream MMR events including strand discrimination and strand-specific excision that are initiated at a significant distance from the mismatch. Remarkably, the biophysical functions of the MLH/PMS proteins have been elusive for decades. Here we consider recent observations that have helped to define the mechanics of MLH/PMS proteins and their role in choreographing MMR. We highlight the stochastic nature of DNA interactions that have been visualized by single-molecule analysis and the plasticity of protein complexes that employ thermal diffusion to complete the progressions of MMR.
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Affiliation(s)
- Jiaquan Liu
- Department of Cancer Biology and Genetics, The Ohio State University Wexner Medical Center, Columbus, 43210, OH, USA
| | - Jong-Bong Lee
- Department of Physics, Pohang University of Science and Technology (POSTECH), 790-784, Pohang, Korea; Interdisciplinary Bioscience and Bioengineering, POSTECH, 790-784, Pohang, Korea.
| | - Richard Fishel
- Department of Cancer Biology and Genetics, The Ohio State University Wexner Medical Center, Columbus, 43210, OH, USA.
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Weßbecher IM, Brieger A. Phosphorylation meets DNA mismatch repair. DNA Repair (Amst) 2018; 72:107-114. [PMID: 30249411 DOI: 10.1016/j.dnarep.2018.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 09/04/2018] [Indexed: 12/14/2022]
Abstract
DNA mismatch repair (MMR) is a highly conserved process and ensures the removal of mispaired DNA bases and insertion-deletion loops right after replication. For this, a MutSα or MutSβ protein complex recognizes the DNA damage, MutLα nicks the erroneous strand, exonuclease 1 removes the wrong nucleotides, DNA polymerase δ refills the gap and DNA ligase I joins the fragments to seal the nicks and complete the repair process. The failure to accomplish these functions is associated with higher mutation rates and may lead to cancer, which highlights the importance of MMR by the maintenance of genomic stability. The post-replicative MMR implies that involved proteins are regulated at several levels, including posttranslational modifications (PTMs). Phosphorylation is one of the most common and major PTMs. Suitable with its regulatory force phosphorylation was shown to influence MMR factors thereby adjusting eukaryotic MMR activity. In this review, we summarized the current knowledge of the role of phosphorylation of MMR process involved proteins and their functional relevance.
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Affiliation(s)
| | - Angela Brieger
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a.M., Germany.
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Weßbecher IM, Hinrichsen I, Funke S, Oellerich T, Plotz G, Zeuzem S, Grus FH, Biondi RM, Brieger A. DNA mismatch repair activity of MutLα is regulated by CK2-dependent phosphorylation of MLH1 (S477). Mol Carcinog 2018; 57:1723-1734. [DOI: 10.1002/mc.22892] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 06/22/2018] [Accepted: 08/18/2018] [Indexed: 12/15/2022]
Affiliation(s)
- Isabel M. Weßbecher
- Medical Clinic I; Biomedical Research Laboratory; Goethe-University; Frankfurt Germany
| | - Inga Hinrichsen
- Medical Clinic I; Biomedical Research Laboratory; Goethe-University; Frankfurt Germany
| | - Sebastian Funke
- Department of Ophthalmology; Experimental Ophthalmology; University Medical Center; Gutenberg University; Mainz Germany
| | - Thomas Oellerich
- Department of Medicine II, Hematology/Oncology; Goethe-University; Frankfurt Germany
| | - Guido Plotz
- Medical Clinic I; Biomedical Research Laboratory; Goethe-University; Frankfurt Germany
| | - Stefan Zeuzem
- Medical Clinic I; Biomedical Research Laboratory; Goethe-University; Frankfurt Germany
| | - Franz H. Grus
- Department of Ophthalmology; Experimental Ophthalmology; University Medical Center; Gutenberg University; Mainz Germany
| | - Ricardo M. Biondi
- Medical Clinic I; Biomedical Research Laboratory; Goethe-University; Frankfurt Germany
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)-CONICET-Partner Institute of the Max Planck Society; Buenos Aires Argentina
| | - Angela Brieger
- Medical Clinic I; Biomedical Research Laboratory; Goethe-University; Frankfurt Germany
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Identification of Exo1-Msh2 interaction motifs in DNA mismatch repair and new Msh2-binding partners. Nat Struct Mol Biol 2018; 25:650-659. [PMID: 30061603 DOI: 10.1038/s41594-018-0092-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 06/14/2018] [Indexed: 02/07/2023]
Abstract
Eukaryotic DNA mismatch repair (MMR) involves both exonuclease 1 (Exo1)-dependent and Exo1-independent pathways. We found that the unstructured C-terminal domain of Saccharomyces cerevisiae Exo1 contains two MutS homolog 2 (Msh2)-interacting peptide (SHIP) boxes downstream from the MutL homolog 1 (Mlh1)-interacting peptide (MIP) box. These three sites were redundant in Exo1-dependent MMR in vivo and could be replaced by a fusion protein between an N-terminal fragment of Exo1 and Msh6. The SHIP-Msh2 interactions were eliminated by the msh2M470I mutation, and wild-type but not mutant SHIP peptides eliminated Exo1-dependent MMR in vitro. We identified two S. cerevisiae SHIP-box-containing proteins and three candidate human SHIP-box-containing proteins. One of these, Fun30, had a small role in Exo1-dependent MMR in vivo. The Remodeling of the Structure of Chromatin (Rsc) complex also functioned in both Exo1-dependent and Exo1-independent MMR in vivo. Our results identified two modes of Exo1 recruitment and a peptide module that mediates interactions between Msh2 and other proteins, and they support a model in which Exo1 functions in MMR by being tethered to the Msh2-Msh6 complex.
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16
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Moufid FZ, Bouguenouch L, El Bouchikhi I, Chbani L, Iraqui Houssaini M, Sekal M, Belhassan K, Bennani B, Ouldim K. The First Molecular Screening of MLH1 and MSH2 Genes in Moroccan Colorectal Cancer Patients Shows a Relatively High Mutational Prevalence. Genet Test Mol Biomarkers 2018; 22:492-497. [PMID: 30044143 DOI: 10.1089/gtmb.2018.0067] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
INTRODUCTION Lynch syndrome (LS) is an autosomal dominant disorder characterized by early age of onset and increased risk of developing extracolonic tumors. Molecular diagnosis of LS requires identification of germline mutations in one of the Mismatch Repair (MMR) genes. AIM The objective of the study was to investigate the prevalence of MLH1/MSH2 mutation carriers among Moroccan patients with colorectal cancer (CRC) in a hospital-based cohort. METHODS In this study, 214 CRC patients from COLORECFez cohort were included. Patients whose tumors showed MMR deficiency (MMR-D) and wild-type BRAF were selected to undergo mutational analysis of the MLH1 and MSH2 genes using Sanger sequencing. RESULTS A total of 24 MMR-D tumors were identified (11.2%) among 214 CRC tested for MMR protein expression. The BRAF p.Val600Glu mutation was absent in all tumors deficient for MLH1 protein. Molecular screening showed germline MMR mutations (MLH1/MSH2) in four cases, two of which fulfilled Amsterdam criteria II and two met at least one of the revised Bethesda guidelines. The estimated frequency of MLH1/MSH2 mutations in Moroccan CRC patients was 1.87%. CONCLUSIONS The present study reports a relatively high incidence of MLH1/MSH2 (1.87%). These results confirm the contribution of MMR genes to CRC susceptibility in our population and provide evidence regarding the requirement of implementing a national screening program for LS in Morocco.
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Affiliation(s)
- Fatima Zahra Moufid
- 1 Department of Medical Genetics and Oncogenetics, Centre Hospitalier Hassam II , Fez, Morocco .,2 Microbial Biotechnology Laboratory, Faculté des Sciences et Techniques, Université Sidi Mohammed Ben Abdellah , Fez, Morocco
| | - Laila Bouguenouch
- 1 Department of Medical Genetics and Oncogenetics, Centre Hospitalier Hassam II , Fez, Morocco .,3 Laboratory of Biomedical and Translational Research, Faculté 3de Médecine et de Pharmacie de Fès, Université Sidi Mohammed Ben Abdellah , Fez, Morocco
| | - Ihssane El Bouchikhi
- 1 Department of Medical Genetics and Oncogenetics, Centre Hospitalier Hassam II , Fez, Morocco .,2 Microbial Biotechnology Laboratory, Faculté des Sciences et Techniques, Université Sidi Mohammed Ben Abdellah , Fez, Morocco
| | - Laila Chbani
- 3 Laboratory of Biomedical and Translational Research, Faculté 3de Médecine et de Pharmacie de Fès, Université Sidi Mohammed Ben Abdellah , Fez, Morocco .,4 Pathological Anatomy and Molecular Pathology Service, Hassan II University Hospital , Fez, Morocco
| | - Mohamed Iraqui Houssaini
- 2 Microbial Biotechnology Laboratory, Faculté des Sciences et Techniques, Université Sidi Mohammed Ben Abdellah , Fez, Morocco
| | - Mohamed Sekal
- 4 Pathological Anatomy and Molecular Pathology Service, Hassan II University Hospital , Fez, Morocco
| | - Khadija Belhassan
- 1 Department of Medical Genetics and Oncogenetics, Centre Hospitalier Hassam II , Fez, Morocco
| | - Bahia Bennani
- 5 Microbiology and Molecular Biology Laboratory, Microorganisms Team, Genomics and Oncogene Factors, Faculté de Médecine et de Pharmacie de Fès, Université Sidi Mohammed Ben Abdellah , Fez, Morocco
| | - Karim Ouldim
- 1 Department of Medical Genetics and Oncogenetics, Centre Hospitalier Hassam II , Fez, Morocco .,3 Laboratory of Biomedical and Translational Research, Faculté 3de Médecine et de Pharmacie de Fès, Université Sidi Mohammed Ben Abdellah , Fez, Morocco
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17
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Tan S, Qin R, Zhu X, Tan C, Song J, Qin L, Liu L, Huang X, Li A, Qiu X. Associations between single-nucleotide polymorphisms of human exonuclease 1 and the risk of hepatocellular carcinoma. Oncotarget 2018; 7:87180-87193. [PMID: 27894089 PMCID: PMC5349980 DOI: 10.18632/oncotarget.13517] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 10/17/2016] [Indexed: 01/27/2023] Open
Abstract
Human exonuclease 1 (hEXO1) is an important nuclease involved in mismatch repair system that contributes to maintain genomic stability and modulate DNA recombination. This study is aimed to explore the associations between single-nucleotide polymorphisms (SNPs) of hEXO1 and the hereditary susceptibility of hepatocellular carcinoma (HCC). SNPs rs1047840, rs1776148, rs3754093, rs4149867, rs4149963, and rs1776181 of hEXO1 were examined from a hospital-based case-control study including 1,196 cases (HCC patients) and 1,199 controls (non-HCC patients) in Guangxi, China. We found the rs3754093 AG genotype decreased the risk of HCC (OR=0.714, 95% CI: 0.539∼0.946). According to the results of stratification analysis, rs3754093 mutant genotype AG/GG decreased the risk of HCC with some HCC protective factors such as non-smoking, non-alcohol consumption and non-HCC family history, but also decreased the risk of HCC with HBV infection. Moreover, it was correlated to non-tumor metastasis and increased the survival of HCC patients. The results from gene-environment interaction assay indicated all hEXO1 SNPs interacted with smoking, alcohol consumption, HBV infection in pathogenesis of HCC. However, gene-gene interaction assay suggested the interaction between rs3754093 and other 5 SNPs were associated with reducing the HCC risk. These results suggest rs3754093 exhibits a protective activity to decrease the incidence risk of HCC in Guangxi, China. In addition, all SNPs in this study interacted with environment risk factors in pathogenesis of HCC.
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Affiliation(s)
- Shengkui Tan
- Department of Epidemiology, School of Public Health, Guilin Medical University, Guilin 541004, Guangxi, People's Republic of China
| | - Ruoyun Qin
- Department of Epidemiology, School of Public Health, Guangxi Medical University, Nanning 530021, Guangxi, People's Republic of China
| | - Xiaonian Zhu
- Department of Epidemiology, School of Public Health, Guilin Medical University, Guilin 541004, Guangxi, People's Republic of China
| | - Chao Tan
- Guangxi Center for Disease Prevention and Control, Nanning 530021, Guangxi, People's Republic of China
| | - Jiale Song
- Department of Epidemiology, School of Public Health, Guilin Medical University, Guilin 541004, Guangxi, People's Republic of China
| | - Linyuan Qin
- Department of Epidemiology, School of Public Health, Guilin Medical University, Guilin 541004, Guangxi, People's Republic of China
| | - Liu Liu
- Department of Epidemiology, School of Public Health, Guangxi Medical University, Nanning 530021, Guangxi, People's Republic of China
| | - Xiong Huang
- Department of Epidemiology, School of Public Health, Guangxi Medical University, Nanning 530021, Guangxi, People's Republic of China
| | - Anhua Li
- Guangxi Center for Disease Prevention and Control, Nanning 530021, Guangxi, People's Republic of China
| | - Xiaoqiang Qiu
- Department of Epidemiology, School of Public Health, Guangxi Medical University, Nanning 530021, Guangxi, People's Republic of China
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18
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Dai Y, Tang Z, Yang Z, Zhang L, Deng Q, Zhang X, Yu Y, Liu X, Zhu J. EXO1 overexpression is associated with poor prognosis of hepatocellular carcinoma patients. Cell Cycle 2018; 17:2386-2397. [PMID: 30328366 PMCID: PMC6237436 DOI: 10.1080/15384101.2018.1534511] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The roles of exonuclease 1 (EXO1) in hepatocellular carcinoma (HCC) tumorigenesis and progression remain unclear. This study aimed to assess the prognostic value and therapeutic potential of EXO1 in HCC. Exo1 gene copy numbers were obtained from three Oncomine microarray datasets (n = 447). EXO1 mRNA expression was validated by semi-quantitative PCR and QuantiGene® 2.0 assays. Cell growth curve and colony formation were performed to asses the cell proliferation. Clonogenic assay, flow cytometry, and immunofluorescence were adopted to acess the effects of EXO1 knockdown and radiation on cell survival, cell cycle distribution and DNA repair. Western blots were performed to reveal the related mechanism. A significant copy number variation (CNV) of the Exo1 gene was found in HCC specimens in three separate sets of published microarray data. In the 143 cases treated by our team, EXO1 expression levels were elevated (86.71%, 124/143). In addition, EXO1 overexpression was correlated with larger tumor size (P = 0.002), increased lymph node metastasis (P=0.033) and lower Edmondson grade (P = 0.018). High EXO1 expression unfavorably affected overall survival (OS) (P = 0.009). Both univariate and multivariate Cox regression analyses identified EXO1 as an independent predictor of OS (univariate, P = 0.012; multivariate, P = 0.039). Silencing of EXO1 in vitro reduced cell proliferation. EXO1 knockdown further suppressed clonogenic cell survival, abrogated radiation-induced G2/M phase arrest, and enhanced γ-H2AX foci after exposure to irradiation. The accumulation of ataxiatelangiectasia mutated (ATM) might partially regulate the EXO1 related radiosensitivity. In summary, EXO1 could be a promising prognostic marker, with a potential therapeutic value in HCC.
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Affiliation(s)
- Yaoyao Dai
- Department of Hepatology, Shanghai municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Zuxiong Tang
- Department of General surgery, the first affiliated hospital of soochow university, suzhou, China
| | - Zongguo Yang
- Department of Central Laboratory Medicine, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Lan Zhang
- Department of Hepatology, Shanghai municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Qing Deng
- Department of Central Laboratory Medicine, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Xiaofeng Zhang
- Department of Central Laboratory Medicine, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yongchun Yu
- Department of Central Laboratory Medicine, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Xing Liu
- Department of Central Laboratory Medicine, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- Shanghai Biochip Corporation LTD./National Engineering Center for Biochip at Shanghai, Shanghai, China
- CONTACT Xing Liu ; Junfeng Zhu
| | - Junfeng Zhu
- Department of Hepatology, Shanghai municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
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19
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Chen CC, Avdievich E, Zhang Y, Zhang Y, Wei K, Lee K, Edelmann W, Jasin M, LaRocque JR. EXO1 suppresses double-strand break induced homologous recombination between diverged sequences in mammalian cells. DNA Repair (Amst) 2017; 57:98-106. [PMID: 28711786 DOI: 10.1016/j.dnarep.2017.07.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 07/05/2017] [Accepted: 07/07/2017] [Indexed: 11/17/2022]
Abstract
DNA double-strand breaks (DSBs) can be repaired through several mechanisms, including homologous recombination (HR). While HR between identical sequences is robust in mammalian cells, HR between diverged sequences is suppressed by DNA mismatch-repair (MMR) components such as MSH2. Exonuclease I (EXO1) interacts with the MMR machinery and has been proposed to act downstream of the mismatch recognition proteins in mismatch correction. EXO1 has also been shown to participate in extensive DSB end resection, an initial step in the HR pathway. To assess the contribution of EXO1 to HR in mammalian cells, DSB-inducible reporters were introduced into Exo1-/- mouse embryonic stem cells, including a novel GFP reporter containing several silent polymorphisms to monitor HR between diverged sequences. Compared to HR between identical sequences which was not clearly affected, HR between diverged sequences was substantially increased in Exo1-/- cells although to a lesser extent than seen in Msh2-/- cells. Thus, like canonical MMR proteins, EXO1 can restrain aberrant HR events between diverged sequence elements in the genome.
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Affiliation(s)
- Chun-Chin Chen
- Developmental Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Ave., New York, NY, 10065, USA; Weill Cornell Graduate School of Medical Sciences, New York, NY, 10065, USA
| | - Elena Avdievich
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, New York, 10461, USA
| | - Yongwei Zhang
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, New York, 10461, USA
| | - Yu Zhang
- Developmental Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Ave., New York, NY, 10065, USA
| | - Kaichun Wei
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, New York, 10461, USA
| | - Kyeryoung Lee
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, New York, 10461, USA
| | - Winfried Edelmann
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, New York, 10461, USA.
| | - Maria Jasin
- Developmental Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Ave., New York, NY, 10065, USA.
| | - Jeannine R LaRocque
- Developmental Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Ave., New York, NY, 10065, USA; Department of Human Science, Georgetown University Medical Center, 3700 Reservoir Rd. NW, Washington, D.C., 20057, USA.
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20
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Keijzers G, Liu D, Rasmussen LJ. Exonuclease 1 and its versatile roles in DNA repair. Crit Rev Biochem Mol Biol 2016; 51:440-451. [PMID: 27494243 DOI: 10.1080/10409238.2016.1215407] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Exonuclease 1 (EXO1) is a multifunctional 5' → 3' exonuclease and a DNA structure-specific DNA endonuclease. EXO1 plays roles in DNA replication, DNA mismatch repair (MMR) and DNA double-stranded break repair (DSBR) in lower and higher eukaryotes and contributes to meiosis, immunoglobulin maturation, and micro-mediated end-joining in higher eukaryotes. In human cells, EXO1 is also thought to play a role in telomere maintenance. Mutations in the human EXO1 gene correlate with increased susceptibility to some cancers. This review summarizes recent studies on the enzymatic functions and biological roles of EXO1, its possible protective role against cancer and aging, and regulation of EXO1 by posttranslational modification.
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Affiliation(s)
- Guido Keijzers
- a Department of Cellular and Molecular Medicine , Center for Healthy Aging, University of Copenhagen , Copenhagen , Denmark
| | - Dekang Liu
- a Department of Cellular and Molecular Medicine , Center for Healthy Aging, University of Copenhagen , Copenhagen , Denmark
| | - Lene Juel Rasmussen
- a Department of Cellular and Molecular Medicine , Center for Healthy Aging, University of Copenhagen , Copenhagen , Denmark
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21
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Oligonucleotide-directed mutagenesis screen to identify pathogenic Lynch syndrome-associated MSH2 DNA mismatch repair gene variants. Proc Natl Acad Sci U S A 2016; 113:4128-33. [PMID: 26951660 DOI: 10.1073/pnas.1520813113] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Single-stranded DNA oligonucleotides can achieve targeted base-pair substitution with modest efficiency but high precision. We show that "oligo targeting" can be used effectively to study missense mutations in DNA mismatch repair (MMR) genes. Inherited inactivating mutations in DNA MMR genes are causative for the cancer predisposition Lynch syndrome (LS). Although overtly deleterious mutations in MMR genes can clearly be ascribed as the cause of LS, the functional implications of missense mutations are often unclear. We developed a genetic screen to determine the pathogenicity of these variants of uncertain significance (VUS), focusing on mutator S homolog 2 (MSH2). VUS were introduced into the endogenous Msh2 gene of mouse embryonic stem cells by oligo targeting. Subsequent selection for MMR-deficient cells using the guanine analog 6-thioguanine allowed the detection of MMR-abrogating VUS. The screen was able to distinguish weak and strong pathogenic variants from polymorphisms and was used to investigate 59 Msh2 VUS. Nineteen of the 59 VUS were identified as pathogenic. Functional assays revealed that 14 of the 19 detected variants fully abrogated MMR activity and that five of the detected variants attenuated MMR activity. Implementation of the screen in clinical practice allows proper counseling of mutation carriers and treatment of their tumors.
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22
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Dynamic control of strand excision during human DNA mismatch repair. Proc Natl Acad Sci U S A 2016; 113:3281-6. [PMID: 26951673 DOI: 10.1073/pnas.1523748113] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Mismatch repair (MMR) is activated by evolutionarily conserved MutS homologs (MSH) and MutL homologs (MLH/PMS). MSH recognizes mismatched nucleotides and form extremely stable sliding clamps that may be bound by MLH/PMS to ultimately authorize strand-specific excision starting at a distant 3'- or 5'-DNA scission. The mechanical processes associated with a complete MMR reaction remain enigmatic. The purified human (Homo sapien or Hs) 5'-MMR excision reaction requires the HsMSH2-HsMSH6 heterodimer, the 5' → 3' exonuclease HsEXOI, and the single-stranded binding heterotrimer HsRPA. The HsMLH1-HsPMS2 heterodimer substantially influences 5'-MMR excision in cell extracts but is not required in the purified system. Using real-time single-molecule imaging, we show that HsRPA or Escherichia coli EcSSB restricts HsEXOI excision activity on nicked or gapped DNA. HsMSH2-HsMSH6 activates HsEXOI by overcoming HsRPA/EcSSB inhibition and exploits multiple dynamic sliding clamps to increase tract length. Conversely, HsMLH1-HsPMS2 regulates tract length by controlling the number of excision complexes, providing a link to 5' MMR.
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23
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Schmoll M, Dattenböck C, Carreras-Villaseñor N, Mendoza-Mendoza A, Tisch D, Alemán MI, Baker SE, Brown C, Cervantes-Badillo MG, Cetz-Chel J, Cristobal-Mondragon GR, Delaye L, Esquivel-Naranjo EU, Frischmann A, Gallardo-Negrete JDJ, García-Esquivel M, Gomez-Rodriguez EY, Greenwood DR, Hernández-Oñate M, Kruszewska JS, Lawry R, Mora-Montes HM, Muñoz-Centeno T, Nieto-Jacobo MF, Nogueira Lopez G, Olmedo-Monfil V, Osorio-Concepcion M, Piłsyk S, Pomraning KR, Rodriguez-Iglesias A, Rosales-Saavedra MT, Sánchez-Arreguín JA, Seidl-Seiboth V, Stewart A, Uresti-Rivera EE, Wang CL, Wang TF, Zeilinger S, Casas-Flores S, Herrera-Estrella A. The Genomes of Three Uneven Siblings: Footprints of the Lifestyles of Three Trichoderma Species. Microbiol Mol Biol Rev 2016; 80:205-327. [PMID: 26864432 PMCID: PMC4771370 DOI: 10.1128/mmbr.00040-15] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The genus Trichoderma contains fungi with high relevance for humans, with applications in enzyme production for plant cell wall degradation and use in biocontrol. Here, we provide a broad, comprehensive overview of the genomic content of these species for "hot topic" research aspects, including CAZymes, transport, transcription factors, and development, along with a detailed analysis and annotation of less-studied topics, such as signal transduction, genome integrity, chromatin, photobiology, or lipid, sulfur, and nitrogen metabolism in T. reesei, T. atroviride, and T. virens, and we open up new perspectives to those topics discussed previously. In total, we covered more than 2,000 of the predicted 9,000 to 11,000 genes of each Trichoderma species discussed, which is >20% of the respective gene content. Additionally, we considered available transcriptome data for the annotated genes. Highlights of our analyses include overall carbohydrate cleavage preferences due to the different genomic contents and regulation of the respective genes. We found light regulation of many sulfur metabolic genes. Additionally, a new Golgi 1,2-mannosidase likely involved in N-linked glycosylation was detected, as were indications for the ability of Trichoderma spp. to generate hybrid galactose-containing N-linked glycans. The genomic inventory of effector proteins revealed numerous compounds unique to Trichoderma, and these warrant further investigation. We found interesting expansions in the Trichoderma genus in several signaling pathways, such as G-protein-coupled receptors, RAS GTPases, and casein kinases. A particularly interesting feature absolutely unique to T. atroviride is the duplication of the alternative sulfur amino acid synthesis pathway.
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Affiliation(s)
- Monika Schmoll
- Austrian Institute of Technology, Department Health and Environment, Bioresources Unit, Tulln, Austria
| | - Christoph Dattenböck
- Austrian Institute of Technology, Department Health and Environment, Bioresources Unit, Tulln, Austria
| | | | | | - Doris Tisch
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, TU Wien, Vienna, Austria
| | - Mario Ivan Alemán
- Cinvestav, Department of Genetic Engineering, Irapuato, Guanajuato, Mexico
| | - Scott E Baker
- Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Christopher Brown
- University of Otago, Department of Biochemistry and Genetics, Dunedin, New Zealand
| | | | - José Cetz-Chel
- LANGEBIO, National Laboratory of Genomics for Biodiversity, Cinvestav-Irapuato, Guanajuato, Mexico
| | | | - Luis Delaye
- Cinvestav, Department of Genetic Engineering, Irapuato, Guanajuato, Mexico
| | | | - Alexa Frischmann
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, TU Wien, Vienna, Austria
| | | | - Monica García-Esquivel
- LANGEBIO, National Laboratory of Genomics for Biodiversity, Cinvestav-Irapuato, Guanajuato, Mexico
| | | | - David R Greenwood
- The University of Auckland, School of Biological Sciences, Auckland, New Zealand
| | - Miguel Hernández-Oñate
- LANGEBIO, National Laboratory of Genomics for Biodiversity, Cinvestav-Irapuato, Guanajuato, Mexico
| | - Joanna S Kruszewska
- Polish Academy of Sciences, Institute of Biochemistry and Biophysics, Laboratory of Fungal Glycobiology, Warsaw, Poland
| | - Robert Lawry
- Lincoln University, Bio-Protection Research Centre, Lincoln, Canterbury, New Zealand
| | | | | | | | | | | | | | - Sebastian Piłsyk
- Polish Academy of Sciences, Institute of Biochemistry and Biophysics, Laboratory of Fungal Glycobiology, Warsaw, Poland
| | - Kyle R Pomraning
- Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Aroa Rodriguez-Iglesias
- Austrian Institute of Technology, Department Health and Environment, Bioresources Unit, Tulln, Austria
| | | | | | - Verena Seidl-Seiboth
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, TU Wien, Vienna, Austria
| | | | | | - Chih-Li Wang
- National Chung-Hsing University, Department of Plant Pathology, Taichung, Taiwan
| | - Ting-Fang Wang
- Academia Sinica, Institute of Molecular Biology, Taipei, Taiwan
| | - Susanne Zeilinger
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, TU Wien, Vienna, Austria University of Innsbruck, Institute of Microbiology, Innsbruck, Austria
| | | | - Alfredo Herrera-Estrella
- LANGEBIO, National Laboratory of Genomics for Biodiversity, Cinvestav-Irapuato, Guanajuato, Mexico
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Chen ZY, Zheng SR, Zhong JH, Zhuang XD, Zhou JY. Association between three exonuclease 1 polymorphisms and cancer risks: a meta-analysis. Onco Targets Ther 2016; 9:899-910. [PMID: 26966378 PMCID: PMC4770079 DOI: 10.2147/ott.s95258] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
To date, the results of studies exploring the relation between exonuclease 1 (Exo1) polymorphisms and cancer risks have differed. In this study, we performed a meta-analysis to investigate the effect of the three most extensively studied Exo1 polymorphisms (Pro757Leu, Glu589Lys, and Glu670Gly) on cancer susceptibility. The related studies published before August 5, 2015, were collected by searching the PubMed and EMBASE databases. We found 16 publications containing studies that were eligible for our study, including 10 studies for Pro757Leu polymorphism (4,093 cases and 3,834 controls), 12 studies for Glu589Lys polymorphism (6,479 cases and 6,550 controls), and 7 studies for Glu670Gly polymorphism (3,700 cases and 3,496 controls). Pooled odds ratios and 95% confidence intervals were used to assess the strength of the associations, and all the statistical analyses were calculated using the software program STATA version 12.0. Our results revealed that the Pro757Leu polymorphism was significantly associated with a reduced cancer risk, whereas an inverse association was found for the Glu589Lys polymorphism. Furthermore, subgroup analysis of smoking status indicated that the Glu589Lys polymorphism was significantly associated with an increased cancer risk in smokers, but not in nonsmokers. However, no evidence was found for an association between the Glu670Gly polymorphism and cancer risk. In conclusion, this meta-analysis suggests that the Pro757Leu polymorphism may provide protective effects against cancer, while the Glu589Lys polymorphism may be a risk factor for cancer. Moreover, the Glu670Gly polymorphism may have no influence on cancer susceptibility. In the future, large-scaled and well-designed studies are needed to achieve a more precise and comprehensive result.
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Affiliation(s)
- Zi-Yu Chen
- Department of Clinical Medicine, The First Clinical Medical College, Southern Medical University, Guangzhou, People's Republic of China; Institute of Genetic Engineering, School of Basic Medical Sciences, Southern Medical University, Guangzhou, People's Republic of China
| | - Si-Rong Zheng
- Institute of Genetic Engineering, School of Basic Medical Sciences, Southern Medical University, Guangzhou, People's Republic of China
| | - Jie-Hui Zhong
- Department of Clinical Medicine, The First Clinical Medical College, Southern Medical University, Guangzhou, People's Republic of China; Institute of Genetic Engineering, School of Basic Medical Sciences, Southern Medical University, Guangzhou, People's Republic of China
| | - Xiao-Duan Zhuang
- Department of Clinical Medicine, The First Clinical Medical College, Southern Medical University, Guangzhou, People's Republic of China; Institute of Genetic Engineering, School of Basic Medical Sciences, Southern Medical University, Guangzhou, People's Republic of China
| | - Jue-Yu Zhou
- Institute of Genetic Engineering, School of Basic Medical Sciences, Southern Medical University, Guangzhou, People's Republic of China
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25
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Single-molecule imaging reveals the mechanism of Exo1 regulation by single-stranded DNA binding proteins. Proc Natl Acad Sci U S A 2016; 113:E1170-9. [PMID: 26884156 DOI: 10.1073/pnas.1516674113] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Exonuclease 1 (Exo1) is a 5'→3' exonuclease and 5'-flap endonuclease that plays a critical role in multiple eukaryotic DNA repair pathways. Exo1 processing at DNA nicks and double-strand breaks creates long stretches of single-stranded DNA, which are rapidly bound by replication protein A (RPA) and other single-stranded DNA binding proteins (SSBs). Here, we use single-molecule fluorescence imaging and quantitative cell biology approaches to reveal the interplay between Exo1 and SSBs. Both human and yeast Exo1 are processive nucleases on their own. RPA rapidly strips Exo1 from DNA, and this activity is dependent on at least three RPA-encoded single-stranded DNA binding domains. Furthermore, we show that ablation of RPA in human cells increases Exo1 recruitment to damage sites. In contrast, the sensor of single-stranded DNA complex 1-a recently identified human SSB that promotes DNA resection during homologous recombination-supports processive resection by Exo1. Although RPA rapidly turns over Exo1, multiple cycles of nuclease rebinding at the same DNA site can still support limited DNA processing. These results reveal the role of single-stranded DNA binding proteins in controlling Exo1-catalyzed resection with implications for how Exo1 is regulated during DNA repair in eukaryotic cells.
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26
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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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27
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Cao Y, Chen Y, Huang Y, Liu Z, Li G. In vitro study of human mutL homolog 1 hypermethylation in inducing drug resistance of esophageal carcinoma. Ir J Med Sci 2016; 186:257-263. [DOI: 10.1007/s11845-016-1401-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Accepted: 01/05/2016] [Indexed: 10/22/2022]
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28
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Shinozuka K, Tang H, Jones RB, Li D, Nieto Y. Impact of Polymorphic Variations of Gemcitabine Metabolism, DNA Damage Repair, and Drug-Resistance Genes on the Effect of High-Dose Chemotherapy for Relapsed or Refractory Lymphoid Malignancies. Biol Blood Marrow Transplant 2015; 22:843-9. [PMID: 26743341 DOI: 10.1016/j.bbmt.2015.12.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 12/22/2015] [Indexed: 10/22/2022]
Abstract
The goal of this study was to determine whether single nucleotide polymorphisms (SNPs) in genes involved in gemcitabine metabolism, DNA damage repair, multidrug resistance, and alkylator detoxification influence the clinical outcome of patients with refractory/relapsed lymphoid malignancies receiving high-dose gemcitabine/busulfan/melphalan (Gem/Bu/Mel) with autologous stem cell support. We evaluated 21 germline SNPs of the gemcitabine metabolism genes CDA, deoxycytidine kinase, and hCNT3; DNA damage repair genes RECQL, X-ray repair complementing 1, RAD54L, ATM, ATR, MLH1, MSH2, MSH3, TREX1, EXO1, and TP73; and multidrug-resistance genes MRP2 and MRP5; as well as glutathione-S-transferase GSTP1 in 153 patients with relapsed or refractory lymphoma or myeloma receiving Gem/Bu/Mel. We studied the association of genotypes with overall survival (OS), progression-free survival (PFS), and nonhematological grade 3 or 4 toxicity. CDA C111T and TREX1 Ex14-460C>T genotypes had a significant effect on OS (P = .007 and P = .005, respectively), and CDA C111T, ATR C340T, and EXO1 P757L genotypes were significant predictors for severe toxicity (P = .037, P = .024, and P = .025, respectively) in multivariable models that adjusted for clinical variables. The multi-SNP risk score analysis identified the combined genotypes of TREX1 Ex14-460 TT and hCNT3 Ex5 +25A>G AA as significant predictors for OS and the combination of MRP2 Ex10 + 40GG/GA and MLH1 IVS12-169 TT as significant predictor for PFS. Polymorphic variants of certain genes involved in gemcitabine metabolism and DNA damage repair pathways may be potential biomarkers for clinical outcome in patients with refractory/relapsed lymphoid tumors receiving Gem/Bu/Mel.
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Affiliation(s)
- Keiji Shinozuka
- Department of Gastrointestinal Medical Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Hongwei Tang
- Department of Gastrointestinal Medical Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Roy B Jones
- Department of Stem Cell Transplantation and Cellular Therapy, University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Donghui Li
- Department of Gastrointestinal Medical Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Yago Nieto
- Department of Stem Cell Transplantation and Cellular Therapy, University of Texas MD Anderson Cancer Center, Houston, Texas.
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29
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Abstract
Highly conserved MutS homologs (MSH) and MutL homologs (MLH/PMS) are the fundamental components of mismatch repair (MMR). After decades of debate, it appears clear that the MSH proteins initiate MMR by recognizing a mismatch and forming multiple extremely stable ATP-bound sliding clamps that diffuse without hydrolysis along the adjacent DNA. The function(s) of MLH/PMS proteins is less clear, although they too bind ATP and are targeted to MMR by MSH sliding clamps. Structural analysis combined with recent real-time single molecule and cellular imaging technologies are providing new and detailed insight into the thermal-driven motions that animate the complete MMR mechanism.
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Affiliation(s)
- Richard Fishel
- From the Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University Wexner Medical Center, Columbus, Ohio 43210 and the Department of Physics and the Biophysics Program, The Ohio State University, Columbus, Ohio 43210
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30
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Doerfler L, Schmidt KH. Exo1 phosphorylation status controls the hydroxyurea sensitivity of cells lacking the Pol32 subunit of DNA polymerases delta and zeta. DNA Repair (Amst) 2015; 24:26-36. [PMID: 25457771 DOI: 10.1016/j.dnarep.2014.10.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 09/29/2014] [Accepted: 10/02/2014] [Indexed: 11/16/2022]
Abstract
Exo1 belongs to the Rad2 family of structure-specific nucleases and possesses 5'-3' exonuclease activity on double-stranded DNA substrates. Exo1 interacts physically with the DNA mismatch repair (MMR) proteins Msh2 and Mlh1 and is involved in the excision of the mispaired nucleotide. Independent of its role in MMR, Exo1 contributes to long-range resection of DNA double-strand break (DSB) ends to facilitate their repair by homologous recombination (HR), and was recently identified as a component of error-free DNA damage tolerance pathways. Here, we show that Exo1 activity increases the hydroxyurea sensitivity of cells lacking Pol32, a subunit of DNA polymerases δ and ζ. Both, phospho-mimicking and dephospho-mimicking exo1 mutants act as hypermorphs, as evidenced by an increase in HU sensitivity of pol32Δ cells, suggesting that they are trapped in an active form and that phosphorylation of Exo1 at residues S372, S567, S587, S692 is necessary, but insufficient, for the accurate regulation of Exo1 activity at stalled replication forks. In contrast, neither phosphorylation status is important for Exo1's role in MMR or in the suppression of genome instability in cells lacking Sgs1 helicase. This ability of an EXO1 deletion to suppress the HU hypersensitivity of pol32Δ cells is in contrast to the negative genetic interaction between deletions of EXO1 and POL32 in MMS-treated cells as well as the role of EXO1 in DNA-damage treated rad53 and mec1 mutants.
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Affiliation(s)
- Lillian Doerfler
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, United States; Graduate Program in Cell and Molecular Biology, University of South Florida, Tampa, FL 33620, United States
| | - Kristina H Schmidt
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, United States; Cancer Biology and Evolution Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, United States.
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31
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Zhang F, Shi J, Bian C, Yu X. Poly(ADP-Ribose) Mediates the BRCA2-Dependent Early DNA Damage Response. Cell Rep 2015; 13:678-689. [PMID: 26489468 DOI: 10.1016/j.celrep.2015.09.040] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 07/26/2015] [Accepted: 09/14/2015] [Indexed: 01/01/2023] Open
Abstract
Breast cancer susceptibility gene 2 (BRCA2) plays a key role in DNA damage repair for maintaining genomic stability. Previous studies have shown that BRCA2 contains three tandem oligonucleotide/oligosaccharide binding folds (OB-folds) that are involved in DNA binding during DNA double-strand break repair. However, the molecular mechanism of BRCA2 in DNA damage repair remains elusive. Unexpectedly, we found that the OB-folds of BRCA2 recognize poly(ADP-ribose) (PAR) and mediate the fast recruitment of BRCA2 to DNA lesions, which is suppressed by PARP inhibitor treatment. Cancer-associated mutations in the OB-folds of BRCA2 disrupt the interaction with PAR and abolish the fast relocation of BRCA2 to DNA lesions. The quickly recruited BRCA2 is important for the early recruitment of exonuclease 1(EXO1) and is involved in DNA end resection, the first step of homologous recombination (HR). Thus, these findings uncover a molecular mechanism by which BRCA2 participates in DNA damage repair.
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Affiliation(s)
- Feng Zhang
- College of Life and Environment Sciences, Shanghai Normal University, Guilin Road 100, Shanghai 200234, China; Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA
| | - Jiazhong Shi
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA; Department of Cell Biology, the Third Military Medical University, Chongqing 400038, China
| | - Chunjing Bian
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA; Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91773, USA
| | - Xiaochun Yu
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA; Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91773, USA.
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32
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Zhang F, Shi J, Chen SH, Bian C, Yu X. The PIN domain of EXO1 recognizes poly(ADP-ribose) in DNA damage response. Nucleic Acids Res 2015; 43:10782-94. [PMID: 26400172 PMCID: PMC4678857 DOI: 10.1093/nar/gkv939] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Accepted: 09/08/2015] [Indexed: 11/14/2022] Open
Abstract
Following DNA double-strand breaks, poly(ADP-ribose) (PAR) is quickly and heavily synthesized to mediate fast and early recruitment of a number of DNA damage response factors to the sites of DNA lesions and facilitates DNA damage repair. Here, we found that EXO1, an exonuclease for DNA damage repair, is quickly recruited to the sites of DNA damage via PAR-binding. With further dissection of the functional domains of EXO1, we report that the PIN domain of EXO1 recognizes PAR both in vitro and in vivo and the interaction between the PIN domain and PAR is sufficient for the recruitment. We also found that the R93G variant of EXO1, generated by a single nucleotide polymorphism, abolishes the interaction and the early recruitment. Moreover, our study suggests that the PAR-mediated fast recruitment of EXO1 facilities early DNA end resection, the first step of homologous recombination repair. We observed that other PIN domains could also recognize DNA damage-induced PAR. Taken together, our study demonstrates a novel class of PAR-binding module that plays an important role in DNA damage response.
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Affiliation(s)
- Feng Zhang
- College of Life and Environment Sciences, Shanghai Normal University, Guilin Road 100, Shanghai 200234, China Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA
| | - Jiazhong Shi
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA Department of Cell Biology, the Third Military Medical University, Chongqing, 400038, China
| | - Shih-Hsun Chen
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91773, USA
| | - Chunjing Bian
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91773, USA
| | - Xiaochun Yu
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 1150 W. Medical Center Drive, 5560 MSRBII, Ann Arbor, MI 48109, USA Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91773, USA
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33
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Human exonuclease 1 (EXO1) activity characterization and its function on flap structures. Biosci Rep 2015; 35:BSR20150058. [PMID: 26182368 PMCID: PMC4613700 DOI: 10.1042/bsr20150058] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 04/24/2015] [Indexed: 11/26/2022] Open
Abstract
We report biochemical characterization of human full-length EXO1 including thermodynamic stability and flap activity on DNA flap structures. Our results reveal novel mechanistic insights into the processing of flap structures and a possible role of EXO1 in strand displacement. Human exonuclease 1 (EXO1) is involved in multiple DNA metabolism processes, including DNA repair and replication. Most of the fundamental roles of EXO1 have been described in yeast. Here, we report a biochemical characterization of human full-length EXO1. Prior to assay EXO1 on different DNA flap structures, we determined factors essential for the thermodynamic stability of EXO1. We show that enzymatic activity and stability of EXO1 on DNA is modulated by temperature. By characterization of EXO1 flap activity using various DNA flap substrates, we show that EXO1 has a strong capacity for degrading double stranded DNA and has a modest endonuclease or 5′ flap activity. Furthermore, we report novel mechanistic insights into the processing of flap structures, showing that EXO1 preferentially cleaves one nucleotide inwards in a double stranded region of a forked and nicked DNA flap substrates, suggesting a possible role of EXO1 in strand displacement.
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34
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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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35
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MicroRNA regulation of DNA repair gene expression in 4-aminobiphenyl-treated HepG2 cells. Toxicology 2014; 322:69-77. [PMID: 24857880 DOI: 10.1016/j.tox.2014.05.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 05/13/2014] [Accepted: 05/13/2014] [Indexed: 11/22/2022]
Abstract
We examined the role of miRNAs in DNA damage response in HepG2 cells following exposure to 4-aminobiphenyl (4-ABP). The arylamine 4-ABP is a human carcinogen. Using the Comet assay, we showed that 4-ABP (18.75-300μM) induces DNA damage in HepG2 cells after 24h. DNA damage signaling pathway-based PCR arrays were used to investigate expression changes in genes involved in DNA damage response. Results showed down-regulation of 16 DNA repair-related genes in 4-ABP-treated cells. Among them, the expression of selected six genes (UNG, LIG1, EXO1, XRCC2, PCNA, and FANCG) from different DNA repair pathways was decreased with quantitative real-time PCR (qRT-PCR). In parallel, using the miRNA array, we reported that the expression of 27 miRNAs in 4-ABP-treated cells was at least 3-fold higher than that in the control group. Of these differential 27 miRNAs, the most significant expression of miRNA-513a-5p and miRNA-630 was further validated by qRT-PCR, and was predicted to be implicated in the deregulation of FANCG and RAD18 genes, respectively, via bioinformatic analysis. Both FANCG and RAD18 proteins were found to be down-regulated in 4-ABP-treated cells. In addition, overexpression and knockdown of miRNA-513a-5p and miRNA-630 reduced and increased the expression of FANCG and RAD18 proteins, respectively. Based on the above results, we indicated that miRNA-513a-5p and miRNA-630 could play a role in the suppression of DNA repair genes, and eventually lead to DNA damage.
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36
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Shao H, Baitinger C, Soderblom EJ, Burdett V, Modrich P. Hydrolytic function of Exo1 in mammalian mismatch repair. Nucleic Acids Res 2014; 42:7104-12. [PMID: 24829455 PMCID: PMC4066806 DOI: 10.1093/nar/gku420] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Genetic and biochemical studies have previously implicated exonuclease 1 (Exo1) in yeast and mammalian mismatch repair, with results suggesting that function of the protein in the reaction depends on both its hydrolytic activity and its ability to interact with other components of the repair system. However, recent analysis of an Exo1-E109K knockin mouse has concluded that Exo1 function in mammalian mismatch repair is restricted to a structural role, a conclusion based on a prior report that N-terminal His-tagged Exo1-E109K is hydrolytically defective. Because Glu-109 is distant from the nuclease hydrolytic center, we have compared the activity of untagged full-length Exo1-E109K with that of wild type Exo1 and the hydrolytically defective active site mutant Exo1-D173A. We show that the activity of Exo1-E109K is comparable to that of wild type enzyme in a conventional exonuclease assay and that in contrast to a D173A active site mutant, Exo1-E109K is fully functional in mismatch-provoked excision and repair. We conclude that the catalytic function of Exo1 is required for its participation in mismatch repair. We also consider the other phenotypes of the Exo1-E109K mouse in the context of Exo1 hydrolytic function.
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Affiliation(s)
- Hongbing Shao
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Celia Baitinger
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - Erik J Soderblom
- Proteomics Core Facility, Duke University Medical Center, Durham, NC 27710, USA
| | - Vickers Burdett
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Paul Modrich
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
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Bregenhorn S, Jiricny J. Biochemical characterization of a cancer-associated E109K missense variant of human exonuclease 1. Nucleic Acids Res 2014; 42:7096-103. [PMID: 24829445 PMCID: PMC4066805 DOI: 10.1093/nar/gku419] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mutations in the mismatch repair (MMR) genes MSH2, MSH6, MLH1 and PMS2 are associated with Lynch Syndrome (LS), a familial predisposition to early-onset cancer of the colon and other organs. Because not all LS families carry mutations in these four genes, the search for cancer-associated mutations was extended to genes encoding other members of the mismatch repairosome. This effort identified mutations in EXO1, which encodes the sole exonuclease implicated in MMR. One of these mutations, E109K, was reported to abrogate the catalytic activity of the enzyme, yet, in the crystal structure of the EXO1/DNA complex, this glutamate is far away from both DNA and the catalytic site of the enzyme. In an attempt to elucidate the reason underlying the putative loss of function of this variant, we expressed it in Escherichia coli, and tested its activity in a series of biochemical assays. We now report that, contrary to earlier reports, and unlike the catalytic site mutant D173A, the EXO1 E109K variant resembled the wild-type (wt) enzyme on all tested substrates. In the light of our findings, we attempt here to reinterpret the results of the phenotypic characterization of a knock-in mouse carrying the E109K mutation and cells derived from it.
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Affiliation(s)
- Stephanie Bregenhorn
- Institute of Molecular Cancer Research of the University of Zurich and the ETH Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Josef Jiricny
- Institute of Molecular Cancer Research of the University of Zurich and the ETH Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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Martín-López JV, Fishel R. The mechanism of mismatch repair and the functional analysis of mismatch repair defects in Lynch syndrome. Fam Cancer 2014; 12:159-68. [PMID: 23572416 DOI: 10.1007/s10689-013-9635-x] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The majority of Lynch syndrome (LS), also known as hereditary non-polyposis colorectal cancer (HNPCC), has been linked to heterozygous defects in DNA mismatch repair (MMR). MMR is a highly conserved pathway that recognizes and repairs polymerase misincorporation errors and nucleotide damage as well as functioning as a damage sensor that signals apoptosis. Loss-of-heterozygosity (LOH) that retains the mutant MMR allele and epigenetic silencing of MMR genes are associated with an increased mutation rate that drives carcinogenesis as well as microsatellite instability that is a hallmark of LS/HNPCC. Understanding the biophysical functions of the MMR components is crucial to elucidating the role of MMR in human tumorigenesis and determining the pathogenetic consequences of patients that present in the clinic with an uncharacterized variant of the MMR genes. We summarize the historical association between LS/HNPCC and MMR, discuss the mechanism of the MMR and finally examine the functional analysis of MMR defects found in LS/HNPCC patients and their relationship with the severity of the disease.
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Affiliation(s)
- Juana V Martín-López
- Department of Molecular Virology, Immunology and Medical Genetics, Human Cancer Genetics, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
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Chen X, Paudyal SC, Chin RI, You Z. PCNA promotes processive DNA end resection by Exo1. Nucleic Acids Res 2013; 41:9325-38. [PMID: 23939618 PMCID: PMC3814391 DOI: 10.1093/nar/gkt672] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Exo1-mediated resection of DNA double-strand break ends generates 3′ single-stranded DNA overhangs required for homology-based DNA repair and activation of the ATR-dependent checkpoint. Despite its critical importance in inducing the overall DNA damage response, the mechanisms and regulation of the Exo1 resection pathway remain incompletely understood. Here, we identify the ring-shaped DNA clamp PCNA as a new factor in the Exo1 resection pathway. Using mammalian cells, Xenopus nuclear extracts and purified proteins, we show that after DNA damage, PCNA loads onto double-strand breaks and promotes Exo1 damage association through direct interaction with Exo1. By tethering Exo1 to the DNA substrate, PCNA confers processivity to Exo1 in resection. This role of PCNA in DNA resection is analogous to its function in DNA replication where PCNA serves as a processivity co-factor for DNA polymerases.
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Affiliation(s)
- Xiaoqing Chen
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
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Campregher C, Schmid G, Ferk F, Knasmüller S, Khare V, Kortüm B, Dammann K, Lang M, Scharl T, Spittler A, Roig AI, Shay JW, Gerner C, Gasche C. MSH3-deficiency initiates EMAST without oncogenic transformation of human colon epithelial cells. PLoS One 2012; 7:e50541. [PMID: 23209772 PMCID: PMC3507781 DOI: 10.1371/journal.pone.0050541] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 10/25/2012] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND/AIM Elevated microsatellite instability at selected tetranucleotide repeats (EMAST) is a genetic signature in certain cases of sporadic colorectal cancer and has been linked to MSH3-deficiency. It is currently controversial whether EMAST is associated with oncogenic properties in humans, specifically as cancer development in Msh3-deficient mice is not enhanced. However, a mutator phenotype is different between species as the genetic positions of repetitive sequences are not conserved. Here we studied the molecular effects of human MSH3-deficiency. METHODS HCT116 and HCT116+chr3 (both MSH3-deficient) and primary human colon epithelial cells (HCEC, MSH3-wildtype) were stably transfected with an EGFP-based reporter plasmid for the detection of frameshift mutations within an [AAAG]17 repeat. MSH3 was silenced by shRNA and changes in protein expression were analyzed by shotgun proteomics. Colony forming assay was used to determine oncogenic transformation and double strand breaks (DSBs) were assessed by Comet assay. RESULTS Despite differential MLH1 expression, both HCT116 and HCT116+chr3 cells displayed comparable high mutation rates (about 4×10(-4)) at [AAAG]17 repeats. Silencing of MSH3 in HCECs leads to a remarkable increased frameshift mutations in [AAAG]17 repeats whereas [CA]13 repeats were less affected. Upon MSH3-silencing, significant changes in the expression of 202 proteins were detected. Pathway analysis revealed overexpression of proteins involved in double strand break repair (MRE11 and RAD50), apoptosis, L1 recycling, and repression of proteins involved in metabolism, tRNA aminoacylation, and gene expression. MSH3-silencing did not induce oncogenic transformation and DSBs increased 2-fold. CONCLUSIONS MSH3-deficiency in human colon epithelial cells results in EMAST, formation of DSBs and significant changes of the proteome but lacks oncogenic transformation. Thus, MSH3-deficiency alone is unlikely to drive human colon carcinogenesis.
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Affiliation(s)
- Christoph Campregher
- Christian Doppler Laboratory for Molecular Cancer Chemoprevention, Division of Gastroenterology and Hepatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria
| | - Gerald Schmid
- Christian Doppler Laboratory for Molecular Cancer Chemoprevention, Division of Gastroenterology and Hepatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria
| | - Franziska Ferk
- Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, Vienna, Austria
| | - Siegfried Knasmüller
- Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, Vienna, Austria
| | - Vineeta Khare
- Christian Doppler Laboratory for Molecular Cancer Chemoprevention, Division of Gastroenterology and Hepatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria
| | - Benedikt Kortüm
- Christian Doppler Laboratory for Molecular Cancer Chemoprevention, Division of Gastroenterology and Hepatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria
| | - Kyle Dammann
- Christian Doppler Laboratory for Molecular Cancer Chemoprevention, Division of Gastroenterology and Hepatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria
| | - Michaela Lang
- Christian Doppler Laboratory for Molecular Cancer Chemoprevention, Division of Gastroenterology and Hepatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria
| | - Theresa Scharl
- ACIB GmbH, c/o Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
- Department of Statistics and Probability Theory, University of Technology, Vienna, Austria
| | - Andreas Spittler
- Department of Surgery, Research Laboratories & Core Facility Flow Cytometry, Medical University of Vienna, Vienna, Austria
| | - Andres I. Roig
- Department of Cell Biology, Division of Digestive and Liver Diseases, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Jerry W. Shay
- Department of Cell Biology, Division of Digestive and Liver Diseases, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Christopher Gerner
- Department of Medicine I, Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria
| | - Christoph Gasche
- Christian Doppler Laboratory for Molecular Cancer Chemoprevention, Division of Gastroenterology and Hepatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria
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Exonuclease 1 (Exo1) is required for activating response to S(N)1 DNA methylating agents. DNA Repair (Amst) 2012; 11:951-64. [PMID: 23062884 DOI: 10.1016/j.dnarep.2012.09.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 09/08/2012] [Accepted: 09/11/2012] [Indexed: 11/23/2022]
Abstract
S(N)1 DNA methylating agents are genotoxic agents that methylate numerous nucleophilic centers within DNA including the O(6) position of guanine (O(6)meG). Methylation of this extracyclic oxygen forces mispairing with thymine during DNA replication. The mismatch repair (MMR) system recognizes these O(6)meG:T mispairs and is required to activate DNA damage response (DDR). Exonuclease I (EXO1) is a key component of MMR by resecting the damaged strand; however, whether EXO1 is required to activate MMR-dependent DDR remains unknown. Here we show that knockdown of the mouse ortholog (mExo1) in mouse embryonic fibroblasts (MEFs) results in decreased G2/M checkpoint response, limited effects on cell proliferation, and increased cell viability following exposure to the S(N)1 methylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), establishing a phenotype paralleling MMR deficiency. MNNG treatment induced formation of γ-H2AX foci with which EXO1 co-localized in MEFs, but mExo1-depleted MEFs displayed a significant diminishment of γ-H2AX foci formation. mExo1 depletion also reduced MSH2 association with DNA duplexes containing G:T mismatches in vitro, decreased MSH2 association with alkylated chromatin in vivo, and abrogated MNNG-induced MSH2/CHK1 interaction. To determine if nuclease activity is required to activate DDR we stably overexpressed a nuclease defective form of human EXO1 (hEXO1) in mExo1-depleted MEFs. These experiments indicated that expression of wildtype and catalytically null hEXO1 was able to restore normal response to MNNG. This study indicates that EXO1 is required to activate MMR-dependent DDR in response to S(N)1 methylating agents; however, this function of EXO1 is independent of its nucleolytic activity.
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Andersen SD, Liberti SE, Lützen A, Drost M, Bernstein I, Nilbert M, Dominguez M, Nyström M, Hansen TVO, Christoffersen JW, Jäger AC, de Wind N, Nielsen FC, Tørring PM, Rasmussen LJ. Functional characterization ofMLH1missense variants identified in lynch syndrome patients. Hum Mutat 2012; 33:1647-55. [DOI: 10.1002/humu.22153] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 06/03/2012] [Indexed: 01/30/2023]
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Shin YK, Amangyeld T, Nguyen TA, Munashingha PR, Seo YS. Human MUS81 complexes stimulate flap endonuclease 1. FEBS J 2012; 279:2412-30. [PMID: 22551069 DOI: 10.1111/j.1742-4658.2012.08620.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The yeast heterodimeric Mus81-Mms4 complex possesses a structure-specific endonuclease activity that is critical for the restart of stalled replication forks and removal of toxic recombination intermediates. Previously, we reported that Mus81-Mms4 and Rad27 (yeast FEN1, another structure-specific endonuclease) showed mutual stimulation of nuclease activity. In this study, we investigated the interactions between human FEN1 and MUS81-EME1 or MUS81-EME2, the human homologs of the yeast Mus81-Mms4 complex. We found that both MUS81-EME1 and MUS81-EME2 increased the activity of FEN1, but FEN1 did not stimulate the activity of MUS81-EME1/EME2. The MUS81 subunit alone and its N-terminal half were able to bind to FEN1 and stimulate its endonuclease activity. A truncated FEN1 fragment lacking the C-terminal region that retained catalytic activity was not stimulated by MUS81. Michaelis-Menten kinetic analysis revealed that MUS81 increased the interaction between FEN1 and its substrates, resulting in increased turnover. We also showed that, after DNA damage in human cells, FEN1 co-localizes with MUS81. These findings indicate that the human proteins and yeast homologs act similarly, except that the human FEN1 does not stimulate the nuclease activities of MUS81-EME1 or MUS81-EME2. Thus, the mammalian MUS81 complexes and FEN1 collaborate to remove the various flap structures that arise during many DNA transactions, including Okazaki fragment processing.
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Affiliation(s)
- Yong-Keol Shin
- Department of Biological Sciences, Center for DNA Replication and Genome Instability, Korea Advanced Institute of Science and Technology, Daejeon, Korea
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Hombauer H, Campbell CS, Smith CE, Desai A, Kolodner RD. Visualization of eukaryotic DNA mismatch repair reveals distinct recognition and repair intermediates. Cell 2012; 147:1040-53. [PMID: 22118461 DOI: 10.1016/j.cell.2011.10.025] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 07/22/2011] [Accepted: 10/07/2011] [Indexed: 11/17/2022]
Abstract
DNA mismatch repair (MMR) increases replication fidelity by eliminating mispaired bases resulting from replication errors. In Saccharomyces cerevisiae, mispairs are primarily detected by the Msh2-Msh6 complex and corrected following recruitment of the Mlh1-Pms1 complex. Here, we visualized functional fluorescent versions of Msh2-Msh6 and Mlh1-Pms1 in living cells. We found that the Msh2-Msh6 complex is an S phase component of replication centers independent of mispaired bases; this localized pool accounted for 10%-15% of MMR in wild-type cells but was essential for MMR in the absence of Exo1. Unexpectedly, Mlh1-Pms1 formed nuclear foci that, although dependent on Msh2-Msh6 for formation, rarely colocalized with Msh2-Msh6 replication-associated foci. Mlh1-Pms1 foci increased when the number of mispaired bases was increased; in contrast, Msh2-Msh6 foci were unaffected. These findings suggest the presence of replication machinery-coupled and -independent pathways for mispair recognition by Msh2-Msh6, which direct formation of superstoichiometric Mlh1-Pms1 foci that represent sites of active MMR.
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Affiliation(s)
- Hans Hombauer
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA
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The functions of MutL in mismatch repair: the power of multitasking. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 110:41-70. [PMID: 22749142 DOI: 10.1016/b978-0-12-387665-2.00003-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
DNA mismatch repair enhances genomic stability by correcting errors that have escaped polymerase proofreading. One of the critical steps in DNA mismatch repair is discriminating the new from the parental DNA strand as only the former needs repair. In Escherichia coli, the latent endonuclease MutH carries out this function. However, most prokaryotes and all eukaryotes lack a mutH gene. MutL is a key component of this system that mediates protein-protein interactions during mismatch recognition, strand discrimination, and strand removal. Hence, it had long been thought that the primary function of MutL was coordinating sequential mismatch repair steps. However, recent studies have revealed that most MutL homologs from organisms lacking MutH encode a conserved metal-binding motif associated with a weak endonuclease activity. As MutL homologs bearing this activity are found only in organisms relying on MutH-independent DNA mismatch repair, this finding unveils yet another crucial function of the MutL protein at the strand discrimination step. In this chapter, we review recent functional and structural work aimed at characterizing the multiple functions of MutL and discuss how the endonuclease activity of MutL is regulated by other repair factors.
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Bayram S, Akkız H, Bekar A, Akgöllü E, Yıldırım S. The significance of Exonuclease 1 K589E polymorphism on hepatocellular carcinoma susceptibility in the Turkish population: a case-control study. Mol Biol Rep 2011; 39:5943-51. [PMID: 22205538 DOI: 10.1007/s11033-011-1406-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 12/17/2011] [Indexed: 02/07/2023]
Abstract
Exonuclease 1 (Exo 1) is an important nuclease involved in mismatch repair system that contributes to maintain genomic stability, to modulate DNA recombination, and to mediate cell cycle arrest. A guanine (G)/adenine (A) common single nucleotide polymorphism at first position of codon 589 in Exo 1 gene determines a glutamic acid (Glu, E) to lysine (Lys, K) (K589E) aminoacidic substitution which may alter cancer risk by influencing the activity of Exo 1 protein. Exo 1 K589E polymorphism has been studied in various cancers, but its association with hepatocellular carcinoma (HCC) has yet to be investigated. To determine the association of the Exo 1 K589E polymorphism with the risk of HCC development in a Turkish population, a hospital-based case-control study was designed consisting of 224 subjects with HCC and 224 cancer-free control subjects matched for age, gender, smoking and alcohol status. The genotype frequency of the Exo 1 K589E polymorphism was determined by using a polymerase chain reaction-restriction fragment length polymorphism assay. Our data shows that the Lys/Lys genotype of the Exo 1 K589E polymorphism is associated with increased risk of HCC development in this Turkish population [odds ratio (OR) = 2.15, 95% confidence interval (CI): 1.13-4.09, P = 0.02]. Furthermore, according to stratified analysis, a significant association was observed between the homozygote Lys/Lys genotype and HCC risk in the subgroups of male gender (OR = 2.67, 95% CI: 1.27-5.61, P = 0.009) and patients with non-viral-related HCC (OR = 3.14, 95% CI: 1.09-8.99, P = 0.03). Because our results suggest for the first time that the Lys/Lys homozygote genotype of Exo 1 K589E polymorphism may be a genetic susceptibility factor for HCC in the Turkish population, further independent studies are required to validate our findings in a larger series, as well as in patients of different ethnic origins.
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Affiliation(s)
- Süleyman Bayram
- Department of Nursing, Adıyaman School of Health, Adıyaman University, 02040, Adıyaman, Turkey.
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Doerfler L, Harris L, Viebranz E, Schmidt KH. Differential genetic interactions between Sgs1, DNA-damage checkpoint components and DNA repair factors in the maintenance of chromosome stability. Genome Integr 2011; 2:8. [PMID: 22040455 PMCID: PMC3231943 DOI: 10.1186/2041-9414-2-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 10/31/2011] [Indexed: 11/21/2022] Open
Abstract
Background Genome instability is associated with human cancers and chromosome breakage syndromes, including Bloom's syndrome, caused by inactivation of BLM helicase. Numerous mutations that lead to genome instability are known, yet how they interact genetically is poorly understood. Results We show that spontaneous translocations that arise by nonallelic homologous recombination in DNA-damage-checkpoint-defective yeast lacking the BLM-related Sgs1 helicase (sgs1Δ mec3Δ) are inhibited if cells lack Mec1/ATR kinase. Tel1/ATM, in contrast, acts as a suppressor independently of Mec3 and Sgs1. Translocations are also inhibited in cells lacking Dun1 kinase, but not in cells defective in a parallel checkpoint branch defined by Chk1 kinase. While we had previously shown that RAD51 deletion did not inhibit translocation formation, RAD59 deletion led to inhibition comparable to the rad52Δ mutation. A candidate screen of other DNA metabolic factors identified Exo1 as a strong suppressor of chromosomal rearrangements in the sgs1Δ mutant, becoming even more important for chromosomal stability upon MEC3 deletion. We determined that the C-terminal third of Exo1, harboring mismatch repair protein binding sites and phosphorylation sites, is dispensable for Exo1's roles in chromosomal rearrangement suppression, mutation avoidance and resistance to DNA-damaging agents. Conclusions Our findings suggest that translocations between related genes can form by Rad59-dependent, Rad51-independent homologous recombination, which is independently suppressed by Sgs1, Tel1, Mec3 and Exo1 but promoted by Dun1 and the telomerase-inhibitor Mec1. We propose a model for the functional interaction between mitotic recombination and the DNA-damage checkpoint in the suppression of chromosomal rearrangements in sgs1Δ cells.
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Affiliation(s)
- Lillian Doerfler
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, 4202 E. Fowler Avenue, Tampa, FL 33620, USA
| | - Lorena Harris
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, 4202 E. Fowler Avenue, Tampa, FL 33620, USA
| | - Emilie Viebranz
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, 4202 E. Fowler Avenue, Tampa, FL 33620, USA
| | - Kristina H Schmidt
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, 4202 E. Fowler Avenue, Tampa, FL 33620, USA
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An activation force-based affinity measure for analyzing complex networks. Sci Rep 2011; 1:113. [PMID: 22355630 PMCID: PMC3216595 DOI: 10.1038/srep00113] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 09/26/2011] [Indexed: 12/13/2022] Open
Abstract
Affinity measure is a key factor that determines the quality of the analysis of a complex network. Here, we introduce a type of statistics, activation forces, to weight the links of a complex network and thereby develop a desired affinity measure. We show that the approach is superior in facilitating the analysis through experiments on a large-scale word network and a protein-protein interaction (PPI) network consisting of ∼5,000 human proteins. The experiment on the word network verifies that the measured word affinities are highly consistent with human knowledge. Further, the experiment on the PPI network verifies the measure and presents a general method for the identification of functionally similar proteins based on PPIs. Most strikingly, we find an affinity network that compactly connects the cancer-associated proteins to each other, which may reveal novel information for cancer study; this includes likely protein interactions and key proteins in cancer-related signal transduction pathways.
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Aberrant methylation of different DNA repair genes demonstrates distinct prognostic value for esophageal cancer. Dig Dis Sci 2011; 56:2992-3004. [PMID: 21674174 DOI: 10.1007/s10620-011-1774-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Accepted: 05/30/2011] [Indexed: 01/25/2023]
Abstract
BACKGROUND DNA mismatch repair (MMR) deficiency results in a strong mutator phenotype and high-frequency microsatellite instability (MSI-H), which are the hallmarks of many tumors. AIM The objective of this study is to investigate the promoter CpG island methylation status of mismatch repair genes human mutL homolog 1 (hMLH1), human mutS homolog 2 (hMSH2), and O(6)-methylguanine-DNA methyltransferase (MGMT) in esophageal squamous cell carcinoma (ESCC) and its roles in alkylating agents chemotherapy. METHODS Real-time methylation-specific polymerase chain reaction (PCR) (real-time MSP) was employed to detect promoter CpG island methylation of the hMLH1, hMSH2, as well as MGMT genes in 235 surgical tumor tissue samples from ESCC patients and their corresponding normal tissue samples. RESULTS Promoter CpG island methylation of hMLH1, hMSH2, and MGMT were detectable in 43.4, 28.9, and 40.4% of ESCC tumor DNA, respectively, and the loss rates of hMLH1, hMSH2, and MGMT protein expression were 48.6, 34.5, and 40.9% in tumor tissues, respectively. For the entire population of 235 ESCC patients who were enrolled in operating treatment combined with radiotherapy and chemotherapy with alkylating agents, there was a significant difference in the overall survival between patients with methylated MGMT promoter and those with an unmethylated MGMT promoter (P < 0.05). CONCLUSION Promoter CpG island methylation may be a frequent event in ESCC carcinogenesis. Detection of the methylated sequences of hMLH1, hMSH2, and MGMT appears to be promising as a predictive factor in primary ESCC.
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Ching Chen S, Hseu YC, Sung JC, Chen CH, Chen LC, Chung KT. Induction of DNA damage signaling genes in benzidine-treated HepG2 cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2011; 52:664-72. [PMID: 21818781 DOI: 10.1002/em.20669] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 06/20/2011] [Accepted: 06/21/2011] [Indexed: 05/10/2023]
Abstract
We examined genotoxicity and DNA damage response in HepG2 cells following exposure to benzidine. Using the Comet assay, we showed that benzidine (50-200 μM) induces DNA damage in HepG2 cells. DNA damage signaling pathway-based PCR arrays were used to investigate expression changes in genes involved in cell-cycle arrest, apoptosis, and DNA repair and showed upregulation of 23 genes and downregulation of one gene in benzidine-treated cells. Induction of G2/M arrest and apoptosis was confirmed at the protein level. Real-time PCR and Western blots were used to demonstrate the expression of select DNA repair-associated genes from the PCR array. Upregulation of the p53 protein in benzidine-treated cells suggests the induction of the p53 DNA damage signaling pathway. Collectively, DNA damage response genes induced by benzidine indicate recruitment complex molecular machinery involved in DNA repair, cell-cycle arrest, and potentially, activation of the apoptosis.
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Affiliation(s)
- Ssu Ching Chen
- Department of Life Science, National Central University, Chung-Li City, Taoyan Country, Taiwan, Republic of China.
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