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Nickoloff JA, Jaiswal AS, Sharma N, Williamson EA, Tran MT, Arris D, Yang M, Hromas R. Cellular Responses to Widespread DNA Replication Stress. Int J Mol Sci 2023; 24:16903. [PMID: 38069223 PMCID: PMC10707325 DOI: 10.3390/ijms242316903] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 11/22/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023] Open
Abstract
Replicative DNA polymerases are blocked by nearly all types of DNA damage. The resulting DNA replication stress threatens genome stability. DNA replication stress is also caused by depletion of nucleotide pools, DNA polymerase inhibitors, and DNA sequences or structures that are difficult to replicate. Replication stress triggers complex cellular responses that include cell cycle arrest, replication fork collapse to one-ended DNA double-strand breaks, induction of DNA repair, and programmed cell death after excessive damage. Replication stress caused by specific structures (e.g., G-rich sequences that form G-quadruplexes) is localized but occurs during the S phase of every cell division. This review focuses on cellular responses to widespread stress such as that caused by random DNA damage, DNA polymerase inhibition/nucleotide pool depletion, and R-loops. Another form of global replication stress is seen in cancer cells and is termed oncogenic stress, reflecting dysregulated replication origin firing and/or replication fork progression. Replication stress responses are often dysregulated in cancer cells, and this too contributes to ongoing genome instability that can drive cancer progression. Nucleases play critical roles in replication stress responses, including MUS81, EEPD1, Metnase, CtIP, MRE11, EXO1, DNA2-BLM, SLX1-SLX4, XPF-ERCC1-SLX4, Artemis, XPG, FEN1, and TATDN2. Several of these nucleases cleave branched DNA structures at stressed replication forks to promote repair and restart of these forks. We recently defined roles for EEPD1 in restarting stressed replication forks after oxidative DNA damage, and for TATDN2 in mitigating replication stress caused by R-loop accumulation in BRCA1-defective cells. We also discuss how insights into biological responses to genome-wide replication stress can inform novel cancer treatment strategies that exploit synthetic lethal relationships among replication stress response factors.
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Affiliation(s)
- Jac A. Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, CO 80523, USA
| | - Aruna S. Jaiswal
- Department of Medicine and the Mays Cancer Center, The University of Texas Health Science Center San Antonio, San Antonio, TX 78229, USA; (A.S.J.); (M.T.T.); (R.H.)
| | - Neelam Sharma
- Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, CO 80523, USA
| | - Elizabeth A. Williamson
- Department of Medicine and the Mays Cancer Center, The University of Texas Health Science Center San Antonio, San Antonio, TX 78229, USA; (A.S.J.); (M.T.T.); (R.H.)
| | - Manh T. Tran
- Department of Medicine and the Mays Cancer Center, The University of Texas Health Science Center San Antonio, San Antonio, TX 78229, USA; (A.S.J.); (M.T.T.); (R.H.)
| | - Dominic Arris
- Department of Medicine and the Mays Cancer Center, The University of Texas Health Science Center San Antonio, San Antonio, TX 78229, USA; (A.S.J.); (M.T.T.); (R.H.)
| | - Ming Yang
- Department of Medicine and the Mays Cancer Center, The University of Texas Health Science Center San Antonio, San Antonio, TX 78229, USA; (A.S.J.); (M.T.T.); (R.H.)
| | - Robert Hromas
- Department of Medicine and the Mays Cancer Center, The University of Texas Health Science Center San Antonio, San Antonio, TX 78229, USA; (A.S.J.); (M.T.T.); (R.H.)
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Hrq1/RECQL4 regulation is critical for preventing aberrant recombination during DNA intrastrand crosslink repair and is upregulated in breast cancer. PLoS Genet 2022; 18:e1010122. [PMID: 36126066 PMCID: PMC9488787 DOI: 10.1371/journal.pgen.1010122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 08/18/2022] [Indexed: 11/19/2022] Open
Abstract
Human RECQL4 is a member of the RecQ family of DNA helicases and functions during DNA replication and repair. RECQL4 mutations are associated with developmental defects and cancer. Although RECQL4 mutations lead to disease, RECQL4 overexpression is also observed in cancer, including breast and prostate. Thus, tight regulation of RECQL4 protein levels is crucial for genome stability. Because mammalian RECQL4 is essential, how cells regulate RECQL4 protein levels is largely unknown. Utilizing budding yeast, we investigated the RECQL4 homolog, HRQ1, during DNA crosslink repair. We find that Hrq1 functions in the error-free template switching pathway to mediate DNA intrastrand crosslink repair. Although Hrq1 mediates repair of cisplatin-induced lesions, it is paradoxically degraded by the proteasome following cisplatin treatment. By identifying the targeted lysine residues, we show that preventing Hrq1 degradation results in increased recombination and mutagenesis. Like yeast, human RECQL4 is similarly degraded upon exposure to crosslinking agents. Furthermore, over-expression of RECQL4 results in increased RAD51 foci, which is dependent on its helicase activity. Using bioinformatic analysis, we observe that RECQL4 overexpression correlates with increased recombination and mutations. Overall, our study uncovers a role for Hrq1/RECQL4 in DNA intrastrand crosslink repair and provides further insight how misregulation of RECQL4 can promote genomic instability, a cancer hallmark. RECQL4 is a DNA helicase and functions during DNA replication and repair. While loss-of-function RECQL4 mutations are found in diseases characterized by developmental defects and cancer, such as Rothmund-Thomson syndrome, over-expression of RECQL4 is also observed in cancer, such as breast cancer. Therefore, RECQL4 protein expression must be tightly regulated. Here we used the budding yeast homolog of RECQL4, Hrq1, and discovered that overexpression of Hrq1 protein levels result in increased recombination and mutations, both cancer hallmarks. We find that Hrq1 functions to mediate repair of a specific type of DNA damage, intrastrand crosslinks, which occur when DNA nucleotides on the same strand are chemically linked together. These findings are also conserved in humans suggesting a common mechanism between yeast Hrq1 and human RECQL4. Overall, our study identifies a conserved role for RECQL4 in DNA intrastrand crosslink repair and provides insights into how its misregulation could promote cancer development.
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Lancey C, Tehseen M, Bakshi S, Percival M, Takahashi M, Sobhy MA, Raducanu VS, Blair K, Muskett FW, Ragan TJ, Crehuet R, Hamdan SM, De Biasio A. Cryo-EM structure of human Pol κ bound to DNA and mono-ubiquitylated PCNA. Nat Commun 2021; 12:6095. [PMID: 34667155 PMCID: PMC8526622 DOI: 10.1038/s41467-021-26251-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 09/22/2021] [Indexed: 11/26/2022] Open
Abstract
Y-family DNA polymerase κ (Pol κ) can replicate damaged DNA templates to rescue stalled replication forks. Access of Pol κ to DNA damage sites is facilitated by its interaction with the processivity clamp PCNA and is regulated by PCNA mono-ubiquitylation. Here, we present cryo-EM reconstructions of human Pol κ bound to DNA, an incoming nucleotide, and wild type or mono-ubiquitylated PCNA (Ub-PCNA). In both reconstructions, the internal PIP-box adjacent to the Pol κ Polymerase-Associated Domain (PAD) docks the catalytic core to one PCNA protomer in an angled orientation, bending the DNA exiting the Pol κ active site through PCNA, while Pol κ C-terminal domain containing two Ubiquitin Binding Zinc Fingers (UBZs) is invisible, in agreement with disorder predictions. The ubiquitin moieties are partly flexible and extend radially away from PCNA, with the ubiquitin at the Pol κ-bound protomer appearing more rigid. Activity assays suggest that, when the internal PIP-box interaction is lost, Pol κ is retained on DNA by a secondary interaction between the UBZs and the ubiquitins flexibly conjugated to PCNA. Our data provide a structural basis for the recruitment of a Y-family TLS polymerase to sites of DNA damage. Translesion Synthesis is a process that enables cells to overcome the deleterious effects of replication stalling caused by DNA lesions. Here the authors present a Cryo-EM structure of human Y-family DNA polymerase k (Pol k) bound to PCNA, P/T DNA and an incoming nucleotide; and propose a model for polymerase switching in which “carrier state” Pol k is recruited to PCNA.
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Affiliation(s)
- Claudia Lancey
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester, LE1 7HB, UK
| | - Muhammad Tehseen
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia
| | - Souvika Bakshi
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester, LE1 7HB, UK
| | - Matthew Percival
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester, LE1 7HB, UK
| | - Masateru Takahashi
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia
| | - Mohamed A Sobhy
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia
| | - Vlad S Raducanu
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia
| | - Kerry Blair
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester, LE1 7HB, UK
| | - Frederick W Muskett
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester, LE1 7HB, UK
| | - Timothy J Ragan
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester, LE1 7HB, UK
| | - Ramon Crehuet
- CSIC-Institute for Advanced Chemistry of Catalonia (IQAC) C/ Jordi Girona 18-26, 08034, Barcelona, Spain
| | - Samir M Hamdan
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia.
| | - Alfredo De Biasio
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester, LE1 7HB, UK. .,Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia.
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Nickoloff JA, Sharma N, Allen CP, Taylor L, Allen SJ, Jaiswal AS, Hromas R. Roles of homologous recombination in response to ionizing radiation-induced DNA damage. Int J Radiat Biol 2021; 99:903-914. [PMID: 34283012 PMCID: PMC9629169 DOI: 10.1080/09553002.2021.1956001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/04/2021] [Accepted: 07/05/2021] [Indexed: 02/06/2023]
Abstract
PURPOSE Ionizing radiation induces a vast array of DNA lesions including base damage, and single- and double-strand breaks (SSB, DSB). DSBs are among the most cytotoxic lesions, and mis-repair causes small- and large-scale genome alterations that can contribute to carcinogenesis. Indeed, ionizing radiation is a 'complete' carcinogen. DSBs arise immediately after irradiation, termed 'frank DSBs,' as well as several hours later in a replication-dependent manner, termed 'secondary' or 'replication-dependent DSBs. DSBs resulting from replication fork collapse are single-ended and thus pose a distinct problem from two-ended, frank DSBs. DSBs are repaired by error-prone nonhomologous end-joining (NHEJ), or generally error-free homologous recombination (HR), each with sub-pathways. Clarifying how these pathways operate in normal and tumor cells is critical to increasing tumor control and minimizing side effects during radiotherapy. CONCLUSIONS The choice between NHEJ and HR is regulated during the cell cycle and by other factors. DSB repair pathways are major contributors to cell survival after ionizing radiation, including tumor-resistance to radiotherapy. Several nucleases are important for HR-mediated repair of replication-dependent DSBs and thus replication fork restart. These include three structure-specific nucleases, the 3' MUS81 nuclease, and two 5' nucleases, EEPD1 and Metnase, as well as three end-resection nucleases, MRE11, EXO1, and DNA2. The three structure-specific nucleases evolved at very different times, suggesting incremental acceleration of replication fork restart to limit toxic HR intermediates and genome instability as genomes increased in size during evolution, including the gain of large numbers of HR-prone repetitive elements. Ionizing radiation also induces delayed effects, observed days to weeks after exposure, including delayed cell death and delayed HR. In this review we highlight the roles of HR in cellular responses to ionizing radiation, and discuss the importance of HR as an exploitable target for cancer radiotherapy.
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Affiliation(s)
- Jac A. Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
| | - Neelam Sharma
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
| | - Christopher P. Allen
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
- Department of Microbiology, Immunology and Pathology, Flow Cytometry and Cell Sorting Facility, Colorado State University, Fort Collins, CO, USA
| | - Lynn Taylor
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
| | - Sage J. Allen
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
| | - Aruna S. Jaiswal
- Division of Hematology and Medical Oncology, Department of Medicine and the Mays Cancer Center, University of Texas Health Science Center, San Antonio, TX, USA
| | - Robert Hromas
- Division of Hematology and Medical Oncology, Department of Medicine and the Mays Cancer Center, University of Texas Health Science Center, San Antonio, TX, USA
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Agostini LC, Jain A, Shupp A, Nevler A, McCarthy G, Bussard KM, Yeo CJ, Brody JR. Combined Targeting of PARG and Wee1 Causes Decreased Cell Survival and DNA Damage in an S-Phase-Dependent Manner. Mol Cancer Res 2020; 19:207-214. [PMID: 33257507 DOI: 10.1158/1541-7786.mcr-20-0708] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 10/15/2020] [Accepted: 11/24/2020] [Indexed: 12/12/2022]
Abstract
The DNA damage response (DDR) pathway sets the stage for tumorigenesis and provides both an opportunity for drug efficacy and resistance. Therapeutic approaches to target the DDR pathway include aiming to increase the efficacy of cytotoxic chemotherapies and synergistic drug strategies to enhance DNA damage, and hence cell death. Here, we report the first preclinical evaluation of a novel synergistic approach by using both genetic and small-molecule inhibition methods of silencing the DDR-related protein, poly (ADP-ribose) glycohydrolase (PARG), and the checkpoint kinase inhibitor, Wee1, in pancreatic ductal adenocarcinoma (PDAC) and colorectal carcinoma cells in vitro and in vivo. Mechanistically, we demonstrate that coinhibition of PARG and Wee1 synergistically decreased cell survival and increased DNA damage in an S-phase-dependent manner. IMPLICATIONS: In preclinical models, we demonstrate the efficacy and mechanism of action of targeting both PARG and Wee1 in PDAC and colorectal carcinoma cells. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/19/2/207/F1.large.jpg.
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Affiliation(s)
- Lebaron C Agostini
- The Jefferson Pancreas, Biliary and Related Cancer Center, Department of Surgery, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Aditi Jain
- The Jefferson Pancreas, Biliary and Related Cancer Center, Department of Surgery, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Alison Shupp
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Avinoam Nevler
- The Jefferson Pancreas, Biliary and Related Cancer Center, Department of Surgery, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Grace McCarthy
- Brenden Colson Center for Pancreatic Care, Departments of Surgery and Cell, Developmental & Cancer Biology, Knight Cancer Institute, Oregon Health and Science University, Portland, Oregon
| | - Karen M Bussard
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Charles J Yeo
- The Jefferson Pancreas, Biliary and Related Cancer Center, Department of Surgery, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Jonathan R Brody
- Brenden Colson Center for Pancreatic Care, Departments of Surgery and Cell, Developmental & Cancer Biology, Knight Cancer Institute, Oregon Health and Science University, Portland, Oregon.
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Mognato M, Burdak-Rothkamm S, Rothkamm K. Interplay between DNA replication stress, chromatin dynamics and DNA-damage response for the maintenance of genome stability. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2020; 787:108346. [PMID: 34083038 DOI: 10.1016/j.mrrev.2020.108346] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 10/02/2020] [Accepted: 11/09/2020] [Indexed: 12/17/2022]
Abstract
DNA replication stress is a major source of DNA damage, including double-stranded breaks that promote DNA damage response (DDR) signaling. Inefficient repair of such lesions can affect genome integrity. During DNA replication different factors act on chromatin remodeling in a coordinated way. While recent studies have highlighted individual molecular mechanisms of interaction, less is known about the orchestration of chromatin changes under replication stress. In this review we attempt to explore the complex relationship between DNA replication stress, DDR and genome integrity in mammalian cells, taking into account the role of chromatin disposition as an important modulator of DNA repair. Recent data on chromatin restoration and epigenetic re-establishment after DNA replication stress are reviewed.
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Affiliation(s)
| | - Susanne Burdak-Rothkamm
- University Medical Center Hamburg-Eppendorf, Department of Radiotherapy, Laboratory of Radiobiology & Experimental Radiation Oncology, Germany.
| | - Kai Rothkamm
- University Medical Center Hamburg-Eppendorf, Department of Radiotherapy, Laboratory of Radiobiology & Experimental Radiation Oncology, Germany.
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Sharma N, Speed MC, Allen CP, Maranon DG, Williamson E, Singh S, Hromas R, Nickoloff JA. Distinct roles of structure-specific endonucleases EEPD1 and Metnase in replication stress responses. NAR Cancer 2020; 2:zcaa008. [PMID: 32743552 PMCID: PMC7380491 DOI: 10.1093/narcan/zcaa008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 05/20/2020] [Accepted: 05/31/2020] [Indexed: 12/16/2022] Open
Abstract
Accurate DNA replication and segregation are critical for maintaining genome integrity and suppressing cancer. Metnase and EEPD1 are DNA damage response (DDR) proteins frequently dysregulated in cancer and implicated in cancer etiology and tumor response to genotoxic chemo- and radiotherapy. Here, we examine the DDR in human cell lines with CRISPR/Cas9 knockout of Metnase or EEPD1. The knockout cell lines exhibit slightly slower growth rates, significant hypersensitivity to replication stress, increased genome instability and distinct alterations in DDR signaling. Metnase and EEPD1 are structure-specific nucleases. EEPD1 is recruited to and cleaves stalled forks to initiate fork restart by homologous recombination. Here, we demonstrate that Metnase is also recruited to stalled forks where it appears to dimethylate histone H3 lysine 36 (H3K36me2), raising the possibility that H3K36me2 promotes DDR factor recruitment or limits nucleosome eviction to protect forks from nucleolytic attack. We show that stalled forks are cleaved normally in the absence of Metnase, an important and novel result because a prior study indicated that Metnase nuclease is important for timely fork restart. A double knockout was as sensitive to etoposide as either single knockout, suggesting a degree of epistasis between Metnase and EEPD1. We propose that EEPD1 initiates fork restart by cleaving stalled forks, and that Metnase may promote fork restart by processing homologous recombination intermediates and/or inducing H3K36me2 to recruit DDR factors. By accelerating fork restart, Metnase and EEPD1 reduce the chance that stalled replication forks will adopt toxic or genome-destabilizing structures, preventing genome instability and cancer. Metnase and EEPD1 are overexpressed in some cancers and thus may also promote resistance to genotoxic therapeutics.
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Affiliation(s)
- Neelam Sharma
- Department of Environmental and Radiological Health Sciences, Colorado State University, 1618 Campus Delivery, Fort Collins, CO 80523-1618, USA
| | - Michael C Speed
- Department of Environmental and Radiological Health Sciences, Colorado State University, 1618 Campus Delivery, Fort Collins, CO 80523-1618, USA
| | - Christopher P Allen
- Department of Microbiology, Immunology, and Pathology, Colorado State University, 1601Campus Delivery, Fort Collins, CO 80523-1601, USA
| | - David G Maranon
- Department of Environmental and Radiological Health Sciences, Colorado State University, 1618 Campus Delivery, Fort Collins, CO 80523-1618, USA
| | - Elizabeth Williamson
- Division of Hematology and Medical Oncology, Department of Medicine, University of Texas HealthScience Center, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Sudha Singh
- Division of Hematology and Medical Oncology, Department of Medicine, University of Texas HealthScience Center, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Robert Hromas
- Division of Hematology and Medical Oncology, Department of Medicine, University of Texas HealthScience Center, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Jac A Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, 1618 Campus Delivery, Fort Collins, CO 80523-1618, USA
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Majera D, Skrott Z, Chroma K, Merchut-Maya JM, Mistrik M, Bartek J. Targeting the NPL4 Adaptor of p97/VCP Segregase by Disulfiram as an Emerging Cancer Vulnerability Evokes Replication Stress and DNA Damage while Silencing the ATR Pathway. Cells 2020; 9:cells9020469. [PMID: 32085572 PMCID: PMC7072750 DOI: 10.3390/cells9020469] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 02/17/2020] [Accepted: 02/17/2020] [Indexed: 12/20/2022] Open
Abstract
Research on repurposing the old alcohol-aversion drug disulfiram (DSF) for cancer treatment has identified inhibition of NPL4, an adaptor of the p97/VCP segregase essential for turnover of proteins involved in multiple pathways, as an unsuspected cancer cell vulnerability. While we reported that NPL4 is targeted by the anticancer metabolite of DSF, the bis-diethyldithiocarbamate-copper complex (CuET), the exact, apparently multifaceted mechanism(s) through which the CuET-induced aggregation of NPL4 kills cancer cells remains to be fully elucidated. Given the pronounced sensitivity to CuET in tumor cell lines lacking the genome integrity caretaker proteins BRCA1 and BRCA2, here we investigated the impact of NPL4 targeting by CuET on DNA replication dynamics and DNA damage response pathways in human cancer cell models. Our results show that CuET treatment interferes with DNA replication, slows down replication fork progression and causes accumulation of single-stranded DNA (ssDNA). Such a replication stress (RS) scenario is associated with DNA damage, preferentially in the S phase, and activates the homologous recombination (HR) DNA repair pathway. At the same time, we find that cellular responses to the CuET-triggered RS are seriously impaired due to concomitant malfunction of the ATRIP-ATR-CHK1 signaling pathway that reflects an unorthodox checkpoint silencing mode through ATR (Ataxia telangiectasia and Rad3 related) kinase sequestration within the CuET-evoked NPL4 protein aggregates.
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Affiliation(s)
- Dusana Majera
- Laboratory of Genome Integrity, Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, 77 147 Olomouc, Czech Republic
| | - Zdenek Skrott
- Laboratory of Genome Integrity, Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, 77 147 Olomouc, Czech Republic
| | - Katarina Chroma
- Laboratory of Genome Integrity, Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, 77 147 Olomouc, Czech Republic
| | | | - Martin Mistrik
- Laboratory of Genome Integrity, Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, 77 147 Olomouc, Czech Republic
- Correspondence: (M.M.); (J.B.)
| | - Jiri Bartek
- Laboratory of Genome Integrity, Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, 77 147 Olomouc, Czech Republic
- Danish Cancer Society Research Center, 2100 Copenhagen, Denmark
- Division of Genome Biology, Department of Medical Biochemistry and Biophysics, Science for Life Laboratory, Karolinska Institute, 171 77 Stockholm, Sweden
- Correspondence: (M.M.); (J.B.)
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9
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Nickoloff JA, Sharma N, Taylor L. Clustered DNA Double-Strand Breaks: Biological Effects and Relevance to Cancer Radiotherapy. Genes (Basel) 2020; 11:E99. [PMID: 31952359 PMCID: PMC7017136 DOI: 10.3390/genes11010099] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/08/2020] [Accepted: 01/14/2020] [Indexed: 01/03/2023] Open
Abstract
Cells manage to survive, thrive, and divide with high accuracy despite the constant threat of DNA damage. Cells have evolved with several systems that efficiently repair spontaneous, isolated DNA lesions with a high degree of accuracy. Ionizing radiation and a few radiomimetic chemicals can produce clustered DNA damage comprising complex arrangements of single-strand damage and DNA double-strand breaks (DSBs). There is substantial evidence that clustered DNA damage is more mutagenic and cytotoxic than isolated damage. Radiation-induced clustered DNA damage has proven difficult to study because the spectrum of induced lesions is very complex, and lesions are randomly distributed throughout the genome. Nonetheless, it is fairly well-established that radiation-induced clustered DNA damage, including non-DSB and DSB clustered lesions, are poorly repaired or fail to repair, accounting for the greater mutagenic and cytotoxic effects of clustered lesions compared to isolated lesions. High linear energy transfer (LET) charged particle radiation is more cytotoxic per unit dose than low LET radiation because high LET radiation produces more clustered DNA damage. Studies with I-SceI nuclease demonstrate that nuclease-induced DSB clusters are also cytotoxic, indicating that this cytotoxicity is independent of radiogenic lesions, including single-strand lesions and chemically "dirty" DSB ends. The poor repair of clustered DSBs at least in part reflects inhibition of canonical NHEJ by short DNA fragments. This shifts repair toward HR and perhaps alternative NHEJ, and can result in chromothripsis-mediated genome instability or cell death. These principals are important for cancer treatment by low and high LET radiation.
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Affiliation(s)
- Jac A. Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA; (N.S.); (L.T.)
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ATM and ATR Influence Meiotic Crossover Formation Through Antagonistic and Overlapping Functions in Caenorhabditis elegans. Genetics 2019; 212:431-443. [PMID: 31015193 DOI: 10.1534/genetics.119.302193] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 04/14/2019] [Indexed: 01/08/2023] Open
Abstract
During meiosis, formation of double-strand breaks (DSBs) and repair by homologous recombination between homologs creates crossovers (COs) that facilitate chromosome segregation. CO formation is tightly regulated to ensure the integrity of this process. The DNA damage response kinases, Ataxia-telangiectasia mutated (ATM) and RAD3-related (ATR) have emerged as key regulators of CO formation in yeast, flies, and mice, influencing DSB formation, repair pathway choice, and cell cycle progression. The molecular networks that ATM and ATR influence during meiosis are still being resolved in other organisms. Here, we show that Caenorhabditis elegans ATM and ATR homologs, ATM-1 and ATL-1 respectively, act at multiple steps in CO formation to ultimately ensure that COs are formed on all chromosomes. We show a role for ATM-1 in regulating the choice of repair template, biasing use of the homologous chromosome instead of the sister chromatid. Our data suggest a model in which ATM-1 and ATL-1 have antagonistic roles in very early repair processing, but are redundantly required for accumulation of the RAD-51 recombinase at DSB sites. We propose that these features of ATM-1 and ATL-1 ensure both CO formation on all chromosomes and accurate repair of additional DSBs.
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11
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DNA Repair Gene Expression Adjusted by the PCNA Metagene Predicts Survival in Multiple Cancers. Cancers (Basel) 2019; 11:cancers11040501. [PMID: 30965671 PMCID: PMC6520950 DOI: 10.3390/cancers11040501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 03/16/2019] [Accepted: 03/30/2019] [Indexed: 02/06/2023] Open
Abstract
Removal of the proliferation component of gene expression by proliferating cell nuclear antigen (PCNA) adjustment via statistical methods has been addressed in numerous survival prediction studies for breast cancer and all cancers in the Cancer Genome Atlas (TCGA). These studies indicate that the removal of proliferation in gene expression by PCNA adjustment removes the statistical significance for predicting overall survival (OS) when gene selection is performed on a genome-wide basis. Since cancers become addicted to DNA repair as a result of forced cellular replication, increased oxidation, and repair deficiencies from oncogenic loss or genetic polymorphisms, we hypothesized that PCNA adjustment of DNA repair gene expression does not remove statistical significance for OS prediction. The rationale and importance of this translational hypothesis is that new lists of repair genes which are predictive of OS can be identified to establish new targets for inhibition therapy. A candidate gene approach was employed using TCGA RNA-Seq data for 121 DNA repair genes in 8 molecular pathways to predict OS for 18 cancers. Statistical randomization test results indicate that after PCNA adjustment, OS could be predicted significantly by sets of DNA repair genes for 61% (11/18) of the cancers. These findings suggest that removal of the proliferation signal in expression by PCNA adjustment does not remove statistical significance for predicting OS. In conclusion, it is likely that previous studies on PCNA adjustment and survival were biased because genes identified through a genome-wide approach are strongly co-regulated by proliferation.
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Peterson LE. Small Molecule Docking of DNA Repair Proteins Associated with Cancer Survival Following PCNA Metagene Adjustment: A Potential Novel Class of Repair Inhibitors. Molecules 2019; 24:E645. [PMID: 30759820 PMCID: PMC6384788 DOI: 10.3390/molecules24030645] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 02/05/2019] [Accepted: 02/11/2019] [Indexed: 11/16/2022] Open
Abstract
Natural and synthetic small molecules from the NCI Developmental Therapeutics Program (DTP) were employed in molecular dynamics-based docking with DNA repair proteins whose RNA-Seq based expression was associated with overall cancer survival (OS) after adjustment for the PCNA metagene. The compounds employed were required to elicit a sensitive response (vs. resistance) in more than half of the cell lines tested for each cancer. Methodological approaches included peptide sequence alignments and homology modeling for 3D protein structure determination, ligand preparation, docking, toxicity and ADME prediction. Docking was performed for unique lists of DNA repair proteins which predict OS for AML, cancers of the breast, lung, colon, and ovaries, GBM, melanoma, and renal papillary cancer. Results indicate hundreds of drug-like and lead-like ligands with best-pose binding energies less than -6 kcal/mol. Ligand solubility for the top 20 drug-like hits approached lower bounds, while lipophilicity was acceptable. Most ligands were also blood-brain barrier permeable with high intestinal absorption rates. While the majority of ligands lacked positive prediction for HERG channel blockage and Ames carcinogenicity, there was a considerable variation for predicted fathead minnow, honey bee, and Tetrahymena pyriformis toxicity. The computational results suggest the potential for new targets and mechanisms of repair inhibition and can be directly employed for in vitro and in vivo confirmatory laboratory experiments to identify new targets of therapy for cancer survival.
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Affiliation(s)
- Leif E Peterson
- Department of Healthcare Policy and Research, Weill Cornell Medical College, Cornell University, New York City, NY 10065, USA.
- Center for Biostatistics, Institute for Academic Medicine, Houston Methodist Research Institute, 6565 Fannin Street, Houston, TX 77030, USA.
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Fang L, Sun X, Wang Y, Du L, Ji K, Wang J, He N, Liu Y, Wang Q, Zhai H, Hao J, Xu C, Liu Q. RMI1 contributes to DNA repair and to the tolerance to camptothecin. FASEB J 2019; 33:5561-5570. [PMID: 30676768 DOI: 10.1096/fj.201802014r] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Maintenance of genome integrity is critical for faithful propagation of genetic information and the prevention of the mutagenesis induced by various DNA damage events. RecQ-mediated genome instability protein 1 (RMI1), together with Bloom syndrome protein and topoisomerase IIIα, form an evolutionarily conserved complex that is critical for the maintenance of genomic stability. Herein, we report that RMI1 depletion increases cell sensitivity to camptothecin treatment, as shown by an elevation of genotoxic stress-induced DNA double-strand breaks, a stronger activation of the DNA damage response, and a greater G2/M cell cycle delay. Our findings support that, upon DNA damage, RMI1 forms nuclear foci at the damaged regions, interacts with RAD51, and facilitates the recruitment of RAD51 to initiate homologous recombination. Our data reveal the importance of RMI1 in response to DNA double-strand breaks and shed light on the molecular mechanisms by which RMI1 contributes to maintain genome stability.-Fang, L., Sun, X., Wang, Y., Du, L., Ji, K., Wang, J., He, N., Liu, Y., Wang, Q., Zhai, H., Hao, J., Xu, C., Liu, Q. RMI1 contributes to DNA repair and to the tolerance to camptothecin.
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Affiliation(s)
- Lianying Fang
- Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China.,The Radiation Medical Institute, Shandong Academy of Medical Sciences, Jinan, China; and
| | - Xiaohui Sun
- Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China
| | - Yan Wang
- Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China
| | - Liqing Du
- Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China
| | - Kaihua Ji
- Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China
| | - Jinhan Wang
- Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China
| | - Ningning He
- Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China
| | - Yang Liu
- Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China
| | - Qin Wang
- Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China
| | - Hezheng Zhai
- Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China
| | - Jianxiu Hao
- Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China
| | - Chang Xu
- Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China.,State Key Laboratory of Medicinal Chemical Biology, NanKai University, Tianjin, China
| | - Qiang Liu
- Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China
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15
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Role of Homologous Recombination Genes in Repair of Alkylation Base Damage by Candida albicans. Genes (Basel) 2018; 9:genes9090447. [PMID: 30205450 PMCID: PMC6162806 DOI: 10.3390/genes9090447] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 08/27/2018] [Indexed: 01/08/2023] Open
Abstract
Candida albicans mutants deficient in homologous recombination (HR) are extremely sensitive to the alkylating agent methyl-methane-sulfonate (MMS). Here, we have investigated the role of HR genes in the protection and repair of C. albicans chromosomes by taking advantage of the heat-labile property (55 °C) of MMS-induced base damage. Acute MMS treatments of cycling cells caused chromosome fragmentation in vitro (55 °C) due to the generation of heat-dependent breaks (HDBs), but not in vivo (30 °C). Following removal of MMS wild type, cells regained the chromosome ladder regardless of whether they were transferred to yeast extract/peptone/dextrose (YPD) or to phosphate buffer saline (PBS); however, repair of HDB/chromosome restitution was faster in YPD, suggesting that it was accelerated by metabolic energy and further fueled by the subsequent overgrowth of survivors. Compared to wild type CAI4, chromosome restitution in YPD was not altered in a Carad59 isogenic derivative, whereas it was significantly delayed in Carad51 and Carad52 counterparts. However, when post-MMS incubation took place in PBS, chromosome restitution in wild type and HR mutants occurred with similar kinetics, suggesting that the exquisite sensitivity of Carad51 and Carad52 mutants to MMS is due to defective fork restart. Overall, our results demonstrate that repair of HDBs by resting cells of C. albicans is rather independent of CaRad51, CaRad52, and CaRad59, suggesting that it occurs mainly by base excision repair (BER).
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16
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Ronson GE, Piberger AL, Higgs MR, Olsen AL, Stewart GS, McHugh PJ, Petermann E, Lakin ND. PARP1 and PARP2 stabilise replication forks at base excision repair intermediates through Fbh1-dependent Rad51 regulation. Nat Commun 2018; 9:746. [PMID: 29467415 PMCID: PMC5821833 DOI: 10.1038/s41467-018-03159-2] [Citation(s) in RCA: 147] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 01/24/2018] [Indexed: 12/22/2022] Open
Abstract
PARP1 regulates the repair of DNA single-strand breaks generated directly, or during base excision repair (BER). However, the role of PARP2 in these and other repair mechanisms is unknown. Here, we report a requirement for PARP2 in stabilising replication forks that encounter BER intermediates through Fbh1-dependent regulation of Rad51. Whereas PARP2 is dispensable for tolerance of cells to SSBs or homologous recombination dysfunction, it is redundant with PARP1 in BER. Therefore, combined disruption of PARP1 and PARP2 leads to defective BER, resulting in elevated levels of replication-associated DNA damage owing to an inability to stabilise Rad51 at damaged replication forks and prevent uncontrolled DNA resection. Together, our results demonstrate how PARP1 and PARP2 regulate two independent, but intrinsically linked aspects of DNA base damage tolerance by promoting BER directly, and by stabilising replication forks that encounter BER intermediates.
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Affiliation(s)
- George E Ronson
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Ann Liza Piberger
- Institute of Cancer and Genomic Sciences, University of Birmingham, Edgbaston, B15 2TT, Birmingham, UK
| | - Martin R Higgs
- Institute of Cancer and Genomic Sciences, University of Birmingham, Edgbaston, B15 2TT, Birmingham, UK
| | - Anna L Olsen
- Department of Oncology, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS, UK
| | - Grant S Stewart
- Institute of Cancer and Genomic Sciences, University of Birmingham, Edgbaston, B15 2TT, Birmingham, UK
| | - Peter J McHugh
- Department of Oncology, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS, UK
| | - Eva Petermann
- Institute of Cancer and Genomic Sciences, University of Birmingham, Edgbaston, B15 2TT, Birmingham, UK
| | - Nicholas D Lakin
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
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Hromas R, Kim HS, Sidhu G, Williamson E, Jaiswal A, Totterdale TA, Nole J, Lee SH, Nickoloff JA, Kong KY. The endonuclease EEPD1 mediates synthetic lethality in RAD52-depleted BRCA1 mutant breast cancer cells. Breast Cancer Res 2017; 19:122. [PMID: 29145865 PMCID: PMC5693420 DOI: 10.1186/s13058-017-0912-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Accepted: 10/30/2017] [Indexed: 02/06/2023] Open
Abstract
Background Proper repair and restart of stressed replication forks requires intact homologous recombination (HR). HR at stressed replication forks can be initiated by the 5′ endonuclease EEPD1, which cleaves the stalled replication fork. Inherited or acquired defects in HR, such as mutations in breast cancer susceptibility protein-1 (BRCA1) or BRCA2, predispose to cancer, including breast and ovarian cancers. In order for these HR-deficient tumor cells to proliferate, they become addicted to a bypass replication fork repair pathway mediated by radiation repair protein 52 (RAD52). Depleting RAD52 can cause synthetic lethality in BRCA1/2 mutant cancers by an unknown molecular mechanism. Methods We hypothesized that cleavage of stressed replication forks by EEPD1 generates a fork repair intermediate that is toxic when HR-deficient cells cannot complete repair with the RAD52 bypass pathway. To test this hypothesis, we applied cell survival assays, immunofluorescence staining, DNA fiber and western blot analyses to look at the correlation between cell survival and genome integrity in control, EEPD1, RAD52 and EEPD1/RAD52 co-depletion BRCA1-deficient breast cancer cells. Results Our data show that depletion of EEPD1 suppresses synthetic lethality, genome instability, mitotic catastrophe, and hypersensitivity to stress of replication of RAD52-depleted, BRCA1 mutant breast cancer cells. Without HR and the RAD52-dependent backup pathway, the BRCA1 mutant cancer cells depleted of EEPD1 skew to the alternative non-homologous end-joining DNA repair pathway for survival. Conclusion This study indicates that the mechanism of synthetic lethality in RAD52-depleted BRCA1 mutant cancer cells depends on the endonuclease EEPD1. The data imply that EEPD1 cleavage of stressed replication forks may result in a toxic intermediate when replication fork repair cannot be completed. Electronic supplementary material The online version of this article (doi:10.1186/s13058-017-0912-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Robert Hromas
- Department of Medicine and the Cancer Center, University of Florida Health, 1600 SW Archer Rd, Gainesville, FL, 32610, USA.
| | - Hyun-Suk Kim
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Gurjit Sidhu
- Department of Medicine and the Cancer Center, University of Florida Health, 1600 SW Archer Rd, Gainesville, FL, 32610, USA
| | - Elizabeth Williamson
- Department of Medicine and the Cancer Center, University of Florida Health, 1600 SW Archer Rd, Gainesville, FL, 32610, USA
| | - Aruna Jaiswal
- Department of Medicine and the Cancer Center, University of Florida Health, 1600 SW Archer Rd, Gainesville, FL, 32610, USA
| | - Taylor A Totterdale
- Department of Medicine and the Cancer Center, University of Florida Health, 1600 SW Archer Rd, Gainesville, FL, 32610, USA
| | - Jocelyn Nole
- Department of Medicine and the Cancer Center, University of Florida Health, 1600 SW Archer Rd, Gainesville, FL, 32610, USA
| | - Suk-Hee Lee
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Jac A Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, 80523, USA
| | - Kimi Y Kong
- Department of Medicine and the Cancer Center, University of Florida Health, 1600 SW Archer Rd, Gainesville, FL, 32610, USA.
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18
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Nickoloff JA, Jones D, Lee SH, Williamson EA, Hromas R. Drugging the Cancers Addicted to DNA Repair. J Natl Cancer Inst 2017; 109:3832892. [PMID: 28521333 PMCID: PMC5436301 DOI: 10.1093/jnci/djx059] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 03/10/2017] [Indexed: 12/29/2022] Open
Abstract
Defects in DNA repair can result in oncogenic genomic instability. Cancers occurring from DNA repair defects were once thought to be limited to rare inherited mutations (such as BRCA1 or 2). It now appears that a clinically significant fraction of cancers have acquired DNA repair defects. DNA repair pathways operate in related networks, and cancers arising from loss of one DNA repair component typically become addicted to other repair pathways to survive and proliferate. Drug inhibition of the rescue repair pathway prevents the repair-deficient cancer cell from replicating, causing apoptosis (termed synthetic lethality). However, the selective pressure of inhibiting the rescue repair pathway can generate further mutations that confer resistance to the synthetic lethal drugs. Many such drugs currently in clinical use inhibit PARP1, a repair component to which cancers arising from inherited BRCA1 or 2 mutations become addicted. It is now clear that drugs inducing synthetic lethality may also be therapeutic in cancers with acquired DNA repair defects, which would markedly broaden their applicability beyond treatment of cancers with inherited DNA repair defects. Here we review how each DNA repair pathway can be attacked therapeutically and evaluate DNA repair components as potential drug targets to induce synthetic lethality. Clinical use of drugs targeting DNA repair will markedly increase when functional and genetic loss of repair components are consistently identified. In addition, future therapies will exploit artificial synthetic lethality, where complementary DNA repair pathways are targeted simultaneously in cancers without DNA repair defects.
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Affiliation(s)
- Jac A Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
| | - Dennie Jones
- Department of Medicine and the Cancer Center, University of Florida Health, Gainesville, FL, USA
| | - Suk-Hee Lee
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Elizabeth A Williamson
- Department of Medicine and the Cancer Center, University of Florida Health, Gainesville, FL, USA
| | - Robert Hromas
- Department of Medicine and the Cancer Center, University of Florida Health, Gainesville, FL, USA
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19
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Paths from DNA damage and signaling to genome rearrangements via homologous recombination. Mutat Res 2017; 806:64-74. [PMID: 28779875 DOI: 10.1016/j.mrfmmm.2017.07.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 07/21/2017] [Indexed: 12/31/2022]
Abstract
DNA damage is a constant threat to genome integrity. DNA repair and damage signaling networks play a central role maintaining genome stability, suppressing tumorigenesis, and determining tumor response to common cancer chemotherapeutic agents and radiotherapy. DNA double-strand breaks (DSBs) are critical lesions induced by ionizing radiation and when replication forks encounter damage. DSBs can result in mutations and large-scale genome rearrangements reflecting mis-repair by non-homologous end joining or homologous recombination. Ionizing radiation induces genetic change immediately, and it also triggers delayed events weeks or even years after exposure, long after the initial damage has been repaired or diluted through cell division. This review covers DNA damage signaling and repair pathways and cell fate following genotoxic insult, including immediate and delayed genome instability and cell survival/cell death pathways.
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20
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Nickoloff JA, Boss MK, Allen CP, LaRue SM. Translational research in radiation-induced DNA damage signaling and repair. Transl Cancer Res 2017; 6:S875-S891. [PMID: 30574452 PMCID: PMC6298755 DOI: 10.21037/tcr.2017.06.02] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Radiotherapy is an effective tool in the fight against cancer. It is non-invasive and painless, and with advanced tumor imaging and beam control systems, radiation can be delivered to patients safely, generally with minor or no adverse side effects, accounting for its increasing use against a broad range of tumors. Tumors and normal cells respond to radiation-induced DNA damage by activating a complex network of DNA damage signaling and repair pathways that determine cell fate including survival, death, and genome stability. DNA damage response (DDR) proteins represent excellent targets to augment radiotherapy, and many agents that inhibit key response proteins are being combined with radiation and genotoxic chemotherapy in clinical trials. This review focuses on how insights into molecular mechanisms of DDR pathways are translated to small animal preclinical studies, to clinical studies of naturally occurring tumors in companion animals, and finally to human clinical trials. Companion animal studies, under the umbrella of comparative oncology, have played key roles in the development of clinical radiotherapy throughout its >100-year history. There is growing appreciation that rapid translation of basic knowledge of DNA damage and repair systems to improved radiotherapy practice requires a comprehensive approach that embraces the full spectrum of cancer research, with companion animal clinical trials representing a critical bridge between small animal preclinical studies, and human clinical trials.
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Affiliation(s)
- Jac A Nickoloff
- Department of Environmental and Radiological Health Sciences, Flint Animal Cancer Center, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
| | - Mary-Keara Boss
- Department of Environmental and Radiological Health Sciences, Flint Animal Cancer Center, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
| | - Christopher P Allen
- Department of Environmental and Radiological Health Sciences, Flint Animal Cancer Center, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
| | - Susan M LaRue
- Department of Environmental and Radiological Health Sciences, Flint Animal Cancer Center, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
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Allen CP, Hirakawa H, Nakajima NI, Moore S, Nie J, Sharma N, Sugiura M, Hoki Y, Araki R, Abe M, Okayasu R, Fujimori A, Nickoloff JA. Low- and High-LET Ionizing Radiation Induces Delayed Homologous Recombination that Persists for Two Weeks before Resolving. Radiat Res 2017; 188:82-93. [PMID: 28535128 DOI: 10.1667/rr14748.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Genome instability is a hallmark of cancer cells and dysregulation or defects in DNA repair pathways cause genome instability and are linked to inherited cancer predisposition syndromes. Ionizing radiation can cause immediate effects such as mutation or cell death, observed within hours or a few days after irradiation. Ionizing radiation also induces delayed effects many cell generations after irradiation. Delayed effects include hypermutation, hyper-homologous recombination, chromosome instability and reduced clonogenic survival (delayed death). Delayed hyperrecombination (DHR) is mechanistically distinct from delayed chromosomal instability and delayed death. Using a green fluorescent protein (GFP) direct repeat homologous recombination system, time-lapse microscopy and colony-based assays, we demonstrate that DHR increases several-fold in response to low-LET X rays and high-LET carbon-ion radiation. Time-lapse analyses of DHR revealed two classes of recombinants not detected in colony-based assays, including cells that recombined and then senesced or died. With both low- and high-LET radiation, DHR was evident during the first two weeks postirradiation, but resolved to background levels during the third week. The results indicate that the risk of radiation-induced genome destabilization via DHR is time limited, and suggest that there is little or no additional risk of radiation-induced genome instability mediated by DHR with high-LET radiation compared to low-LET radiation.
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Affiliation(s)
- Christopher P Allen
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, Colorado
| | - Hirokazu Hirakawa
- b Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences, Chiba, Japan
| | - Nakako Izumi Nakajima
- b Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences, Chiba, Japan
| | - Sophia Moore
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, Colorado
| | - Jingyi Nie
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, Colorado
| | - Neelam Sharma
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, Colorado
| | - Mayumi Sugiura
- c Division of Natural Sciences, Research Group of Biological Sciences, Nara Women's University, Nara, Japan
| | - Yuko Hoki
- b Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences, Chiba, Japan
| | - Ryoko Araki
- b Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences, Chiba, Japan
| | - Masumi Abe
- b Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences, Chiba, Japan
| | - Ryuichi Okayasu
- b Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences, Chiba, Japan
| | - Akira Fujimori
- b Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences, Chiba, Japan
| | - Jac A Nickoloff
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, Colorado
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Kim HS, Williamson EA, Nickoloff JA, Hromas RA, Lee SH. Metnase Mediates Loading of Exonuclease 1 onto Single Strand Overhang DNA for End Resection at Stalled Replication Forks. J Biol Chem 2016; 292:1414-1425. [PMID: 27974460 DOI: 10.1074/jbc.m116.745646] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 12/13/2016] [Indexed: 11/06/2022] Open
Abstract
Stalling at DNA replication forks generates stretches of single-stranded (ss) DNA on both strands that are exposed to nucleolytic degradation, potentially compromising genome stability. One enzyme crucial for DNA replication fork repair and restart of stalled forks in human is Metnase (also known as SETMAR), a chimeric fusion protein consisting of a su(var)3-9, enhancer-of-zeste and trithorax (SET) histone methylase and transposase nuclease domain. We previously showed that Metnase possesses a unique fork cleavage activity necessary for its function in replication restart and that its SET domain is essential for recovery from hydroxyurea-induced DNA damage. However, its exact role in replication restart is unclear. In this study, we show that Metnase associates with exonuclease 1 (Exo1), a 5'-exonuclease crucial for 5'-end resection to mediate DNA processing at stalled forks. Metnase DNA cleavage activity was not required for Exo1 5'-exonuclease activity on the lagging strand daughter DNA, but its DNA binding activity mediated loading of Exo1 onto ssDNA overhangs. Metnase-induced enhancement of Exo1-mediated DNA strand resection required the presence of these overhangs but did not require Metnase's DNA cleavage activity. These results suggest that Metnase enhances Exo1-mediated exonuclease activity on the lagging strand DNA by facilitating Exo1 loading onto a single strand gap at the stalled replication fork.
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Affiliation(s)
- Hyun-Suk Kim
- From the Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Elizabeth A Williamson
- the Department of Medicine, University of Florida and Shands Health Care System, Gainesville, Florida 32610, and
| | - Jac A Nickoloff
- the Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523
| | - Robert A Hromas
- the Department of Medicine, University of Florida and Shands Health Care System, Gainesville, Florida 32610, and
| | - Suk-Hee Lee
- From the Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202,
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Parplys AC, Seelbach JI, Becker S, Behr M, Wrona A, Jend C, Mansour WY, Joosse SA, Stuerzbecher HW, Pospiech H, Petersen C, Dikomey E, Borgmann K. High levels of RAD51 perturb DNA replication elongation and cause unscheduled origin firing due to impaired CHK1 activation. Cell Cycle 2016; 14:3190-202. [PMID: 26317153 DOI: 10.1080/15384101.2015.1055996] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In response to replication stress ATR signaling through CHK1 controls the intra-S checkpoint and is required for the maintenance of genomic integrity. Homologous recombination (HR) comprises a series of interrelated pathways that function in the repair of DNA double strand breaks and interstrand crosslinks. In addition, HR, with its key player RAD51, provides critical support for the recovery of stalled forks during replication. High levels of RAD51 are regularly found in various cancers, yet little is known about the effect of the increased RAD51 expression on intra-S checkpoint signaling. Here, we describe a role for RAD51 in driving genomic instability caused by impaired replication and intra-S mediated CHK1 signaling by studying an inducible RAD51 overexpression model as well as 10 breast cancer cell lines. We demonstrate that an excess of RAD51 decreases I-Sce-I mediated HR despite formation of more RAD51 foci. Cells with high RAD51 levels display reduced elongation rates and excessive dormant origin firing during undisturbed growth and after damage, likely caused by impaired CHK1 activation. In consequence, the inability of cells with a surplus of RAD51 to properly repair complex DNA damage and to resolve replication stress leads to higher genomic instability and thus drives tumorigenesis.
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Affiliation(s)
- Ann Christin Parplys
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Jasna Irena Seelbach
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Saskia Becker
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Matthias Behr
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Agnieszka Wrona
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Camilla Jend
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Wael Yassin Mansour
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany.,b Tumor Biology Department; National Cancer Institute; Cairo University ; Cairo , Egypt
| | - Simon Andreas Joosse
- d Department of Tumor Biology ; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | | | - Helmut Pospiech
- f Leibniz Institute for Age Research - Fritz Lipmann Institute ; Jena , Germany.,g Faculty of Biochemistry and Molecular Medicine; University of Oulu ; Oulu , Finland
| | - Cordula Petersen
- c Department of Radiotherapy and Radiooncology ; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Ekkehard Dikomey
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Kerstin Borgmann
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
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24
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Getting Ready for the Dance: FANCJ Irons Out DNA Wrinkles. Genes (Basel) 2016; 7:genes7070031. [PMID: 27376332 PMCID: PMC4962001 DOI: 10.3390/genes7070031] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/13/2016] [Accepted: 06/27/2016] [Indexed: 12/21/2022] Open
Abstract
Mounting evidence indicates that alternate DNA structures, which deviate from normal double helical DNA, form in vivo and influence cellular processes such as replication and transcription. However, our understanding of how the cellular machinery deals with unusual DNA structures such as G-quadruplexes (G4), triplexes, or hairpins is only beginning to emerge. New advances in the field implicate a direct role of the Fanconi Anemia Group J (FANCJ) helicase, which is linked to a hereditary chromosomal instability disorder and important for cancer suppression, in replication past unusual DNA obstacles. This work sets the stage for significant progress in dissecting the molecular mechanisms whereby replication perturbation by abnormal DNA structures leads to genomic instability. In this review, we focus on FANCJ and its role to enable efficient DNA replication when the fork encounters vastly abundant naturally occurring DNA obstacles, which may have implications for targeting rapidly dividing cancer cells.
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25
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Gao X, Zhang G, Shan S, Shang Y, Chi L, Li H, Cao Y, Zhu X, Zhang M, Yang J. Depletion of Paraspeckle Protein 1 Enhances Methyl Methanesulfonate-Induced Apoptosis through Mitotic Catastrophe. PLoS One 2016; 11:e0146952. [PMID: 26785254 PMCID: PMC4718682 DOI: 10.1371/journal.pone.0146952] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 12/22/2015] [Indexed: 11/19/2022] Open
Abstract
Previously, we have shown that paraspeckle protein 1 (PSPC1), a protein component of paraspeckles that was involved in cisplatin-induced DNA damage response (DDR), probably functions at the G1/S checkpoint. In the current study, we further examined the role of PSPC1 in another DNA-damaging agent, methyl methanesulfonate (MMS)-induced DDR, in particular, focusing on MMS-induced apoptosis in HeLa cells. First, it was found that MMS treatment induced the expression of PSPC1. While MMS treatment alone can induce apoptosis, depletion of PSPC1 expression using siRNA significantly increased the level of apoptosis following MMS exposure. In contrast, overexpressing PSPC1 decreased the number of apoptotic cells. Interestingly, morphological observation revealed that many of the MMS-treated PSPC1-knockdown cells contained two or more nuclei, indicating the occurrence of mitotic catastrophe. Cell cycle analysis further showed that depletion of PSPC1 caused more cells entering the G2/M phase, a prerequisite of mitosis catastrophe. On the other hand, over-expressing PSPC1 led to more cells accumulating in the G1/S phase. Taken together, these observations suggest an important role for PSPC1 in MMS-induced DDR, and in particular, depletion of PSPC1 can enhance MMS-induced apoptosis through mitotic catastrophe.
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Affiliation(s)
- Xiangjing Gao
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang, 310051, China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, Zhejiang, 310003, China
| | - Guanglin Zhang
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, Zhejiang, 310003, China
| | - Shigang Shan
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, Zhejiang, 310003, China
| | - Yunlong Shang
- Zhejiang CONBA Pharmaceutical Co. Ltd., Hangzhou, Zhejiang, 310058, China
| | - Linfeng Chi
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, Zhejiang, 310003, China
- The Affiliated Stomatology Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310003, China
| | - Hongjuan Li
- Department of Toxicology, Hangzhou Normal University School of Medicine, Hangzhou, Zhejiang, 310016, China
| | - Yifei Cao
- Department of Toxicology, Hangzhou Normal University School of Medicine, Hangzhou, Zhejiang, 310016, China
| | - Xinqiang Zhu
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, Zhejiang, 310003, China
| | - Meibian Zhang
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang, 310051, China
- * E-mail: (MBZ); (JY)
| | - Jun Yang
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, Zhejiang, 310003, China
- Department of Toxicology, Hangzhou Normal University School of Medicine, Hangzhou, Zhejiang, 310016, China
- * E-mail: (MBZ); (JY)
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26
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Ucisik MN, Hammes-Schiffer S. Comparative Molecular Dynamics Studies of Human DNA Polymerase η. J Chem Inf Model 2015; 55:2672-81. [PMID: 26562587 PMCID: PMC4696480 DOI: 10.1021/acs.jcim.5b00606] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
High-energy
ultraviolet radiation damages DNA through the formation
of cyclobutane pyrimidine dimers, which stall replication. When the
lesion is a thymine–thymine dimer (TTD), human DNA polymerase
η (Pol η) assists in resuming the replication process
by inserting nucleotides opposite the damaged site. We performed extensive
molecular dynamics (MD) simulations to investigate the structural
and dynamical effects of four different Pol η complexes with
or without a TTD and with either dATP or dGTP as the incoming base.
No major differences in the overall structures and equilibrium dynamics
were detected among the four systems, suggesting that the specificity
of this enzyme is due predominantly to differences in local interactions
in the binding regions. Analysis of the hydrogen-bonding interactions
between the enzyme and the DNA and dNTP provided molecular-level insights.
Specifically, the TTD was observed to engage in more hydrogen-bonding
interactions with the enzyme than its undamaged counterpart of two
normal thymines. The resulting greater rigidity and specific orientation
of the TTD are consistent with the experimental observation of higher
processivity and overall efficiency at TTD sites than at analogous
sites with two normal thymines. The similarities between the systems
containing dATP and dGTP are consistent with the experimental observation
of relatively low fidelity with respect to the incoming base. Moreover,
Q38 and R61, two strictly conserved amino acids across the Pol η
family, were found to exhibit persistent hydrogen-bonding interactions
with the TTD and cation-π interactions with the free base, respectively.
Thus, these simulations provide molecular level insights into the
basis for the selectivity and efficiency of this enzyme, as well as
the roles of the two most strictly conserved residues.
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Affiliation(s)
- Melek N Ucisik
- Department of Chemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801-3364, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801-3364, United States
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27
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Bélanger F, Angers JP, Fortier É, Hammond-Martel I, Costantino S, Drobetsky E, Wurtele H. Mutations in Replicative Stress Response Pathways Are Associated with S Phase-specific Defects in Nucleotide Excision Repair. J Biol Chem 2015; 291:522-37. [PMID: 26578521 DOI: 10.1074/jbc.m115.685883] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Indexed: 01/02/2023] Open
Abstract
Nucleotide excision repair (NER) is a highly conserved pathway that removes helix-distorting DNA lesions induced by a plethora of mutagens, including UV light. Our laboratory previously demonstrated that human cells deficient in either ATM and Rad3-related (ATR) kinase or translesion DNA polymerase η (i.e. key proteins that promote the completion of DNA replication in response to UV-induced replicative stress) are characterized by profound inhibition of NER exclusively during S phase. Toward elucidating the mechanistic basis of this phenomenon, we developed a novel assay to quantify NER kinetics as a function of cell cycle in the model organism Saccharomyces cerevisiae. Using this assay, we demonstrate that in yeast, deficiency of the ATR homologue Mec1 or of any among several other proteins involved in the cellular response to replicative stress significantly abrogates NER uniquely during S phase. Moreover, initiation of DNA replication is required for manifestation of this defect, and S phase NER proficiency is correlated with the capacity of individual mutants to respond to replicative stress. Importantly, we demonstrate that partial depletion of Rfa1 recapitulates defective S phase-specific NER in wild type yeast; moreover, ectopic RPA1-3 overexpression rescues such deficiency in either ATR- or polymerase η-deficient human cells. Our results strongly suggest that reduction of NER capacity during periods of enhanced replicative stress, ostensibly caused by inordinate sequestration of RPA at stalled DNA replication forks, represents a conserved feature of the multifaceted eukaryotic DNA damage response.
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Affiliation(s)
- François Bélanger
- From the Centre de Recherche de l'Hôpital Maisonneuve-Rosemont, Montréal, Québec H1T 2M4, Canada and
| | - Jean-Philippe Angers
- From the Centre de Recherche de l'Hôpital Maisonneuve-Rosemont, Montréal, Québec H1T 2M4, Canada and the Programme de Biologie Moléculaire
| | - Émile Fortier
- From the Centre de Recherche de l'Hôpital Maisonneuve-Rosemont, Montréal, Québec H1T 2M4, Canada and
| | - Ian Hammond-Martel
- From the Centre de Recherche de l'Hôpital Maisonneuve-Rosemont, Montréal, Québec H1T 2M4, Canada and
| | - Santiago Costantino
- From the Centre de Recherche de l'Hôpital Maisonneuve-Rosemont, Montréal, Québec H1T 2M4, Canada and Département d'ophtalmologie, and
| | - Elliot Drobetsky
- From the Centre de Recherche de l'Hôpital Maisonneuve-Rosemont, Montréal, Québec H1T 2M4, Canada and Département de Médecine, Université de Montréal, Montréal, Québec H3T 1J4, Canada
| | - Hugo Wurtele
- From the Centre de Recherche de l'Hôpital Maisonneuve-Rosemont, Montréal, Québec H1T 2M4, Canada and Département de Médecine, Université de Montréal, Montréal, Québec H3T 1J4, Canada
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28
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Lau WCY, Li Y, Zhang Q, Huen MSY. Molecular architecture of the Ub-PCNA/Pol η complex bound to DNA. Sci Rep 2015; 5:15759. [PMID: 26503230 PMCID: PMC4621508 DOI: 10.1038/srep15759] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 09/29/2015] [Indexed: 01/13/2023] Open
Abstract
Translesion synthesis (TLS) is the mechanism by which DNA polymerases replicate through unrepaired DNA lesions. TLS is activated by monoubiquitination of the homotrimeric proliferating cell nuclear antigen (PCNA) at lysine-164, followed by the switch from replicative to specialized polymerases at DNA damage sites. Pol η belongs to the Y-Family of specialized polymerases that can efficiently bypass UV-induced lesions. Like other members of the Y-Family polymerases, its recruitment to the damaged sites is mediated by the interaction with monoubiquitinated PCNA (Ub-PCNA) via its ubiquitin-binding domain and non-canonical PCNA-interacting motif in the C-terminal region. The structural determinants underlying the direct recognition of Ub-PCNA by Pol η, or Y-Family polymerases in general, remain largely unknown. Here we report a structure of the Ub-PCNA/Pol η complex bound to DNA determined by single-particle electron microscopy (EM). The overall obtained structure resembles that of the editing PCNA/PolB complex. Analysis of the map revealed the conformation of ubiquitin that binds the C-terminal domain of Pol η. Our present study suggests that the Ub-PCNA/Pol η interaction requires the formation of a structured binding interface, which is dictated by the inherent flexibility of Ub-PCNA.
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Affiliation(s)
- Wilson C Y Lau
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China.,State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, China
| | - Yinyin Li
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Qinfen Zhang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Michael S Y Huen
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China.,State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, China
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29
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Kim HS, Kim SK, Hromas R, Lee SH. The SET Domain Is Essential for Metnase Functions in Replication Restart and the 5' End of SS-Overhang Cleavage. PLoS One 2015; 10:e0139418. [PMID: 26437079 PMCID: PMC4593633 DOI: 10.1371/journal.pone.0139418] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 09/14/2015] [Indexed: 11/19/2022] Open
Abstract
Metnase (also known as SETMAR) is a chimeric SET-transposase protein that plays essential role(s) in non-homologous end joining (NHEJ) repair and replication fork restart. Although the SET domain possesses histone H3 lysine 36 dimethylation (H3K36me2) activity associated with an improved association of early repair components for NHEJ, its role in replication restart is less clear. Here we show that the SET domain is necessary for the recovery from DNA damage at the replication forks following hydroxyurea (HU) treatment. Cells overexpressing the SET deletion mutant caused a delay in fork restart after HU release. Our In vitro study revealed that the SET domain but not the H3K36me2 activity is required for the 5’ end of ss-overhang cleavage with fork and non-fork DNA without affecting the Metnase-DNA interaction. Together, our results suggest that the Metnase SET domain has a positive role in restart of replication fork and the 5’ end of ss-overhang cleavage, providing a new insight into the functional interaction of the SET and the transposase domains.
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Affiliation(s)
- Hyun-Suk Kim
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Sung-Kyung Kim
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Robert Hromas
- Department of Medicine, University of Florida and Shands Health Care System, Gainesville, Florida, United States of America
| | - Suk-Hee Lee
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Indiana University Simon Cancer Center, Indianapolis, Indiana, United States of America
- * E-mail:
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30
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King C, Diaz HB, McNeely S, Barnard D, Dempsey J, Blosser W, Beckmann R, Barda D, Marshall MS. LY2606368 Causes Replication Catastrophe and Antitumor Effects through CHK1-Dependent Mechanisms. Mol Cancer Ther 2015; 14:2004-13. [PMID: 26141948 DOI: 10.1158/1535-7163.mct-14-1037] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 06/27/2015] [Indexed: 12/13/2022]
Abstract
CHK1 is a multifunctional protein kinase integral to both the cellular response to DNA damage and control of the number of active replication forks. CHK1 inhibitors are currently under investigation as chemopotentiating agents due to CHK1's role in establishing DNA damage checkpoints in the cell cycle. Here, we describe the characterization of a novel CHK1 inhibitor, LY2606368, which as a single agent causes double-stranded DNA breakage while simultaneously removing the protection of the DNA damage checkpoints. The action of LY2606368 is dependent upon inhibition of CHK1 and the corresponding increase in CDC25A activation of CDK2, which increases the number of replication forks while reducing their stability. Treatment of cells with LY2606368 results in the rapid appearance of TUNEL and pH2AX-positive double-stranded DNA breaks in the S-phase cell population. Loss of the CHK1-dependent DNA damage checkpoints permits cells with damaged DNA to proceed into early mitosis and die. The majority of treated mitotic nuclei consist of extensively fragmented chromosomes. Inhibition of apoptosis by the caspase inhibitor Z-VAD-FMK had no effect on chromosome fragmentation, indicating that LY2606368 causes replication catastrophe. Changes in the ratio of RPA2 to phosphorylated H2AX following LY2606368 treatment further support replication catastrophe as the mechanism of DNA damage. LY2606368 shows similar activity in xenograft tumor models, which results in significant tumor growth inhibition. LY2606368 is a potent representative of a novel class of drugs for the treatment of cancer that acts through replication catastrophe.
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Affiliation(s)
- Constance King
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - H Bruce Diaz
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - Samuel McNeely
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - Darlene Barnard
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - Jack Dempsey
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - Wayne Blosser
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - Richard Beckmann
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - David Barda
- Chemistry Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - Mark S Marshall
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana.
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31
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DNA polymerases β and λ and their roles in cell. DNA Repair (Amst) 2015; 29:112-26. [DOI: 10.1016/j.dnarep.2015.02.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 01/29/2015] [Accepted: 02/02/2015] [Indexed: 10/24/2022]
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32
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Interplay between histone H3 lysine 56 deacetylation and chromatin modifiers in response to DNA damage. Genetics 2015; 200:185-205. [PMID: 25786853 DOI: 10.1534/genetics.115.175919] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Accepted: 03/12/2015] [Indexed: 01/23/2023] Open
Abstract
In Saccharomyces cerevisiae, histone H3 lysine 56 acetylation (H3K56Ac) is present in newly synthesized histones deposited throughout the genome during DNA replication. The sirtuins Hst3 and Hst4 deacetylate H3K56 after S phase, and virtually all histone H3 molecules are K56 acetylated throughout the cell cycle in hst3∆ hst4∆ mutants. Failure to deacetylate H3K56 causes thermosensitivity, spontaneous DNA damage, and sensitivity to replicative stress via molecular mechanisms that remain unclear. Here we demonstrate that unlike wild-type cells, hst3∆ hst4∆ cells are unable to complete genome duplication and accumulate persistent foci containing the homologous recombination protein Rad52 after exposure to genotoxic drugs during S phase. In response to replicative stress, cells lacking Hst3 and Hst4 also displayed intense foci containing the Rfa1 subunit of the single-stranded DNA binding protein complex RPA, as well as persistent activation of DNA damage-induced kinases. To investigate the basis of these phenotypes, we identified histone point mutations that modulate the temperature and genotoxic drug sensitivity of hst3∆ hst4∆ cells. We found that reducing the levels of histone H4 lysine 16 acetylation or H3 lysine 79 methylation partially suppresses these sensitivities and reduces spontaneous and genotoxin-induced activation of the DNA damage-response kinase Rad53 in hst3∆ hst4∆ cells. Our data further suggest that elevated DNA damage-induced signaling significantly contributes to the phenotypes of hst3∆ hst4∆ cells. Overall, these results outline a novel interplay between H3K56Ac, H3K79 methylation, and H4K16 acetylation in the cellular response to DNA damage.
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33
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Nicolae CM, Aho ER, Choe KN, Constantin D, Hu HJ, Lee D, Myung K, Moldovan GL. A novel role for the mono-ADP-ribosyltransferase PARP14/ARTD8 in promoting homologous recombination and protecting against replication stress. Nucleic Acids Res 2015; 43:3143-53. [PMID: 25753673 PMCID: PMC4381061 DOI: 10.1093/nar/gkv147] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 02/15/2015] [Indexed: 12/29/2022] Open
Abstract
Genomic instability, a major hallmark of cancer cells, is caused by incorrect or ineffective DNA repair. Many DNA repair mechanisms cooperate in cells to fight DNA damage, and are generally regulated by post-translational modification of key factors. Poly-ADP-ribosylation, catalyzed by PARP1, is a post-translational modification playing a prominent role in DNA repair, but much less is known about mono-ADP-ribosylation. Here we report that mono-ADP-ribosylation plays an important role in homologous recombination DNA repair, a mechanism essential for replication fork stability and double strand break repair. We show that the mono-ADP-ribosyltransferase PARP14 interacts with the DNA replication machinery component PCNA and promotes replication of DNA lesions and common fragile sites. PARP14 depletion results in reduced homologous recombination, persistent RAD51 foci, hypersensitivity to DNA damaging agents and accumulation of DNA strand breaks. Our work uncovered PARP14 as a novel factor required for mitigating replication stress and promoting genomic stability.
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Affiliation(s)
- Claudia M Nicolae
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA
| | - Erin R Aho
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA
| | - Katherine N Choe
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA
| | - Daniel Constantin
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA
| | - He-Juan Hu
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA Suzhou Health College, Suzhou, Jiangsu 215009, P.R. China
| | - Deokjae Lee
- Genome Instability Section, National Human Genome Research Institute, Bethesda, MD 20892, USA
| | - Kyungjae Myung
- Genome Instability Section, National Human Genome Research Institute, Bethesda, MD 20892, USA
| | - George-Lucian Moldovan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA
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34
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Family L, Bensen JT, Troester MA, Wu MC, Anders CK, Olshan AF. Single-nucleotide polymorphisms in DNA bypass polymerase genes and association with breast cancer and breast cancer subtypes among African Americans and Whites. Breast Cancer Res Treat 2015; 149:181-90. [PMID: 25417172 PMCID: PMC4498665 DOI: 10.1007/s10549-014-3203-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 11/09/2014] [Indexed: 01/18/2023]
Abstract
DNA damage recognition and repair is a complex system of genes focused on maintaining genomic stability. Recently, there has been a focus on how breast cancer susceptibility relates to genetic variation in the DNA bypass polymerases pathway. Race-stratified and subtype-specific logistic regression models were used to estimate odds ratios (ORs) and 95 % confidence intervals (CIs) for the association between 22 single-nucleotide polymorphisms (SNPs) in seven bypass polymerase genes and breast cancer risk in the Carolina Breast Cancer Study, a population-based, case-control study (1,972 cases and 1,776 controls). We used SNP-set kernel association test (SKAT) to evaluate the multi-gene, multi-locus (combined) SNP effects within bypass polymerase genes. We found similar ORs for breast cancer with three POLQ SNPs (rs487848 AG/AA vs. GG; OR = 1.31, 95 % CI 1.03-1.68 for Whites and OR = 1.22, 95 % CI 1.00-1.49 for African Americans), (rs532411 CT/TT vs. CC; OR = 1.31, 95 % CI 1.02-1.66 for Whites and OR = 1.22, 95 % CI 1.00-1.48 for African Americans), and (rs3218634 CG/CC vs. GG; OR = 1.29, 95 % CI 1.02-1.65 for Whites). These three SNPs are in high linkage disequilibrium in both races. Tumor subtype analysis showed the same SNPs to be associated with increased risk of Luminal breast cancer. SKAT analysis showed no significant combined SNP effects. These results suggest that variants in the POLQ gene may be associated with the risk of Luminal breast cancer.
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Affiliation(s)
- Leila Family
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA,
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35
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Franchitto A, Pichierri P. Replication fork recovery and regulation of common fragile sites stability. Cell Mol Life Sci 2014; 71:4507-17. [PMID: 25216703 PMCID: PMC11113654 DOI: 10.1007/s00018-014-1718-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 08/28/2014] [Indexed: 10/24/2022]
Abstract
The acquisition of genomic instability is a triggering factor in cancer development, and common fragile sites (CFS) are the preferential target of chromosomal instability under conditions of replicative stress in the human genome. Although the mechanisms leading to CFS expression and the cellular factors required to suppress CFS instability remain largely undefined, it is clear that DNA becomes more susceptible to breakage when replication is impaired. The models proposed so far to explain how CFS instability arises imply that replication fork progression along these regions is perturbed due to intrinsic features of fragile sites and events that directly affect DNA replication. The observation that proteins implicated in the safe recovery of stalled forks or in engaging recombination at collapsed forks increase CFS expression when downregulated or mutated suggests that the stabilization and recovery of perturbed replication forks are crucial to guarantee CFS integrity.
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Affiliation(s)
- Annapaola Franchitto
- Section of Molecular Epidemiology, Department of Environment and Primary Prevention, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161, Rome, Italy,
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36
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Accumulation of abasic sites induces genomic instability in normal human gastric epithelial cells during Helicobacter pylori infection. Oncogenesis 2014; 3:e128. [PMID: 25417725 PMCID: PMC4259965 DOI: 10.1038/oncsis.2014.42] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 10/07/2014] [Accepted: 10/15/2014] [Indexed: 12/11/2022] Open
Abstract
Helicobacter pylori infection of the human stomach is associated with inflammation that leads to the release of reactive oxygen and nitrogen species (RONs), eliciting DNA damage in host cells. Unrepaired DNA damage leads to genomic instability that is associated with cancer. Base excision repair (BER) is critical to maintain genomic stability during RONs-induced DNA damage, but little is known about its role in processing DNA damage associated with H. pylori infection of normal gastric epithelial cells. Here, we show that upon H. pylori infection, abasic (AP) sites accumulate and lead to increased levels of double-stranded DNA breaks (DSBs). In contrast, downregulation of the OGG1 DNA glycosylase decreases the levels of both AP sites and DSBs during H. pylori infection. Processing of AP sites during different phases of the cell cycle leads to an elevation in the levels of DSBs. Therefore, the induction of oxidative DNA damage by H. pylori and subsequent processing by BER in normal gastric epithelial cells has the potential to lead to genomic instability that may have a role in the development of gastric cancer. Our results are consistent with the interpretation that precise coordination of BER processing of DNA damage is critical for the maintenance of genomic stability.
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Ashley AK, Shrivastav M, Nie J, Amerin C, Troksa K, Glanzer JG, Liu S, Opiyo SO, Dimitrova DD, Le P, Sishc B, Bailey SM, Oakley GG, Nickoloff JA. DNA-PK phosphorylation of RPA32 Ser4/Ser8 regulates replication stress checkpoint activation, fork restart, homologous recombination and mitotic catastrophe. DNA Repair (Amst) 2014; 21:131-9. [PMID: 24819595 DOI: 10.1016/j.dnarep.2014.04.008] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Revised: 03/17/2014] [Accepted: 04/14/2014] [Indexed: 11/17/2022]
Abstract
Genotoxins and other factors cause replication stress that activate the DNA damage response (DDR), comprising checkpoint and repair systems. The DDR suppresses cancer by promoting genome stability, and it regulates tumor resistance to chemo- and radiotherapy. Three members of the phosphatidylinositol 3-kinase-related kinase (PIKK) family, ATM, ATR, and DNA-PK, are important DDR proteins. A key PIKK target is replication protein A (RPA), which binds single-stranded DNA and functions in DNA replication, DNA repair, and checkpoint signaling. An early response to replication stress is ATR activation, which occurs when RPA accumulates on ssDNA. Activated ATR phosphorylates many targets, including the RPA32 subunit of RPA, leading to Chk1 activation and replication arrest. DNA-PK also phosphorylates RPA32 in response to replication stress, and we demonstrate that cells with DNA-PK defects, or lacking RPA32 Ser4/Ser8 targeted by DNA-PK, confer similar phenotypes, including defective replication checkpoint arrest, hyper-recombination, premature replication fork restart, failure to block late origin firing, and increased mitotic catastrophe. We present evidence that hyper-recombination in these mutants is ATM-dependent, but the other defects are ATM-independent. These results indicate that DNA-PK and ATR signaling through RPA32 plays a critical role in promoting genome stability and cell survival in response to replication stress.
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Affiliation(s)
- Amanda K Ashley
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States
| | - Meena Shrivastav
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Jingyi Nie
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States
| | - Courtney Amerin
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States
| | - Kyle Troksa
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States
| | - Jason G Glanzer
- Department of Oral Biology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Shengqin Liu
- Department of Oral Biology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Stephen O Opiyo
- Department of Oral Biology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Diana D Dimitrova
- Department of Oral Biology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Phuong Le
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States
| | - Brock Sishc
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States
| | - Susan M Bailey
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States
| | - Greg G Oakley
- Department of Oral Biology, University of Nebraska Medical Center, Omaha, NE, United States; Eppley Cancer Center, University of Nebraska Medical Center, Omaha, NE, United States
| | - Jac A Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States; Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, Albuquerque, NM, United States.
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38
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Yang W. An overview of Y-Family DNA polymerases and a case study of human DNA polymerase η. Biochemistry 2014; 53:2793-803. [PMID: 24716551 PMCID: PMC4018060 DOI: 10.1021/bi500019s] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
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Y-Family
DNA polymerases specialize in translesion synthesis, bypassing
damaged bases that would otherwise block the normal progression of
replication forks. Y-Family polymerases have unique structural features
that allow them to bind damaged DNA and use a modified template base
to direct nucleotide incorporation. Each Y-Family polymerase is unique
and has different preferences for lesions to bypass and for dNTPs
to incorporate. Y-Family polymerases are also characterized by a low
catalytic efficiency, a low processivity, and a low fidelity on normal
DNA. Recruitment of these specialized polymerases to replication forks
is therefore regulated. The catalytic center of the Y-Family polymerases
is highly conserved and homologous to that of high-fidelity and high-processivity
DNA replicases. In this review, structural differences between Y-Family
and A- and B-Family polymerases are compared and correlated with their
functional differences. A time-resolved X-ray crystallographic study
of the DNA synthesis reaction catalyzed by the Y-Family DNA polymerase
human polymerase η revealed transient elements that led to the
nucleotidyl-transfer reaction.
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Affiliation(s)
- Wei Yang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland 20892, United States
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Brown AD, Sager BW, Gorthi A, Tonapi SS, Brown EJ, Bishop AJR. ATR suppresses endogenous DNA damage and allows completion of homologous recombination repair. PLoS One 2014; 9:e91222. [PMID: 24675793 PMCID: PMC3968013 DOI: 10.1371/journal.pone.0091222] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 02/10/2014] [Indexed: 11/28/2022] Open
Abstract
DNA replication fork stalling or collapse that arises from endogenous damage poses a serious threat to genome stability, but cells invoke an intricate signaling cascade referred to as the DNA damage response (DDR) to prevent such damage. The gene product ataxia telangiectasia and Rad3-related (ATR) responds primarily to replication stress by regulating cell cycle checkpoint control, yet it’s role in DNA repair, particularly homologous recombination (HR), remains unclear. This is of particular interest since HR is one way in which replication restart can occur in the presence of a stalled or collapsed fork. Hypomorphic mutations in human ATR cause the rare autosomal-recessive disease Seckel syndrome, and complete loss of Atr in mice leads to embryonic lethality. We recently adapted the in vivo murine pink-eyed unstable (pun) assay for measuring HR frequency to be able to investigate the role of essential genes on HR using a conditional Cre/loxP system. Our system allows for the unique opportunity to test the effect of ATR loss on HR in somatic cells under physiological conditions. Using this system, we provide evidence that retinal pigment epithelium (RPE) cells lacking ATR have decreased density with abnormal morphology, a decreased frequency of HR and an increased level of chromosomal damage.
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Affiliation(s)
- Adam D. Brown
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Greehey Children’s Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Brian W. Sager
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Greehey Children’s Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Aparna Gorthi
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Greehey Children’s Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Sonal S. Tonapi
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Greehey Children’s Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Eric J. Brown
- Abramson Family Cancer Research Institute, Department of Cancer Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Alexander J. R. Bishop
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Greehey Children’s Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Cancer Therapy and Research Center, University of Texas Health Science Center, San Antonio, Texas, United States of America
- * E-mail:
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40
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Abbas M, Shanmugam I, Bsaili M, Hromas R, Shaheen M. The role of the human psoralen 4 (hPso4) protein complex in replication stress and homologous recombination. J Biol Chem 2014; 289:14009-19. [PMID: 24675077 DOI: 10.1074/jbc.m113.520056] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Psoralen 4 (Pso4) is an evolutionarily conserved protein that has been implicated in a variety of cellular processes including RNA splicing and resistance to agents that cause DNA interstrand cross-links. Here we show that the hPso4 complex is required for timely progression through S phase and transition through the G2/M checkpoint, and it functions in the repair of DNA lesions that arise during replication. Notably, hPso4 depletion results in delayed resumption of DNA replication after hydroxyurea-induced stalling of replication forks, reduced repair of spontaneous and hydroxyurea-induced DNA double strand breaks (DSBs), and increased sensitivity to a poly(ADP-ribose) polymerase inhibitor. Furthermore, we show that hPso4 is involved in the repair of DSBs by homologous recombination, probably by regulating the BRCA1 protein levels and the generation of single strand DNA at DSBs. Together, our results demonstrate that hPso4 participates in cell proliferation and the maintenance of genome stability by regulating homologous recombination. The involvement of hPso4 in the recombinational repair of DSBs provides an explanation for the sensitivity of Pso4-deficient cells to DNA interstrand cross-links.
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Affiliation(s)
- Mohammad Abbas
- From the Division of Hematology-Oncology, Department of Internal Medicine, University of New Mexico, Albuquerque, New Mexico 87131 and
| | - Ilanchezhian Shanmugam
- From the Division of Hematology-Oncology, Department of Internal Medicine, University of New Mexico, Albuquerque, New Mexico 87131 and
| | - Manal Bsaili
- From the Division of Hematology-Oncology, Department of Internal Medicine, University of New Mexico, Albuquerque, New Mexico 87131 and
| | - Robert Hromas
- the Department of Medicine, University of Florida, Gainesville, Florida 32611
| | - Monte Shaheen
- From the Division of Hematology-Oncology, Department of Internal Medicine, University of New Mexico, Albuquerque, New Mexico 87131 and
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41
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Yu H, Lim HH, Tjokro NO, Sathiyanathan P, Natarajan S, Chew TW, Klonisch T, Goodman SD, Surana U, Dröge P. Chaperoning HMGA2 protein protects stalled replication forks in stem and cancer cells. Cell Rep 2014; 6:684-97. [PMID: 24508460 DOI: 10.1016/j.celrep.2014.01.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 11/26/2013] [Accepted: 01/14/2014] [Indexed: 10/25/2022] Open
Abstract
Maintaining genome integrity requires the accurate and complete replication of chromosomal DNA. This is of the utmost importance for embryonic stem cells (ESCs), which differentiate into cells of all lineages, including germ cells. However, endogenous and exogenous factors frequently induce stalling of replication forks in every cell cycle, which can trigger mutations and chromosomal instabilities. We show here that the oncofetal, nonhistone chromatin factor HMGA2 equips cells with a highly effective first-line defense mechanism against endonucleolytic collapse of stalled forks. This fork-stabilizing function most likely employs scaffold formation at branched DNA via multiple DNA-binding domains. Moreover, HMGA2 works independently of other human factors in two heterologous cell systems to prevent DNA strand breaks. This fork chaperone function seemingly evolved to preserve ESC genome integrity. It is hijacked by tumor (stem) cells to also guard their genomes against DNA-damaging agents widely used to treat cancer patients.
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Affiliation(s)
- Haojie Yu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Hong Hwa Lim
- Institute of Molecular and Cell Biology, Proteos, 61 Biopolis Drive, Singapore 138673, Singapore; Bioprocessing Technology Institute, 20 Biopolis Way, 6-01 Centros, Singapore 138668, Singapore
| | - Natalia O Tjokro
- Division of Biomedical Sciences, The Herman Ostrow School of Dentistry of the University of Southern California, Los Angeles, CA 90089, USA
| | - Padmapriya Sathiyanathan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Suchitra Natarajan
- Department of Human Anatomy and Cell Science, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Tian Wei Chew
- Institute of Molecular and Cell Biology, Proteos, 61 Biopolis Drive, Singapore 138673, Singapore
| | - Thomas Klonisch
- Department of Human Anatomy and Cell Science, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3E 0J9, Canada; Department of Medical Microbiology and Infectious Diseases, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3E 0J9, Canada; Department of Surgery, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Steven D Goodman
- Division of Biomedical Sciences, The Herman Ostrow School of Dentistry of the University of Southern California, Los Angeles, CA 90089, USA
| | - Uttam Surana
- Institute of Molecular and Cell Biology, Proteos, 61 Biopolis Drive, Singapore 138673, Singapore
| | - Peter Dröge
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
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42
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Genome instability at common fragile sites: searching for the cause of their instability. BIOMED RESEARCH INTERNATIONAL 2013; 2013:730714. [PMID: 24083238 PMCID: PMC3780545 DOI: 10.1155/2013/730714] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Accepted: 08/07/2013] [Indexed: 12/24/2022]
Abstract
Common fragile sites (CFS) are heritable nonrandomly distributed loci on human chromosomes that exhibit an increased frequency of chromosomal breakage under conditions of replication stress. They are considered the preferential targets for high genomic instability from the earliest stages of human cancer development, and increased chromosome instability at these loci has been observed following replication stress in a subset of human genetic diseases. Despite their biological and medical relevance, the molecular basis of CFS fragility in vivo has not been fully elucidated. At present, different models have been proposed to explain how instability at CFS arises and multiple factors seem to contribute to their instability. However, all these models involve DNA replication and suggest that replication fork stalling along CFS during DNA synthesis is a very frequent event. Consistent with this, the maintenance of CFS stability relies on the ATR-dependent checkpoint, together with a number of proteins promoting the recovery of stalled replication forks. In this review, we discuss mainly the possible causes that threaten the integrity of CFS in the light of new findings, paying particular attention to the role of the S-phase checkpoint.
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43
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Mason JM, Das I, Arlt M, Patel N, Kraftson S, Glover TW, Sekiguchi JM. The SNM1B/APOLLO DNA nuclease functions in resolution of replication stress and maintenance of common fragile site stability. Hum Mol Genet 2013; 22:4901-13. [PMID: 23863462 DOI: 10.1093/hmg/ddt340] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
SNM1B/Apollo is a DNA nuclease that has important functions in telomere maintenance and repair of DNA interstrand crosslinks (ICLs) within the Fanconi anemia (FA) pathway. SNM1B is required for efficient localization of key repair proteins, such as the FA protein, FANCD2, to sites of ICL damage and functions epistatically to FANCD2 in cellular survival to ICLs and homology-directed repair. The FA pathway is also activated in response to replication fork stalling. Here, we sought to determine the importance of SNM1B in cellular responses to stalled forks in the absence of a blocking lesion, such as ICLs. We found that depletion of SNM1B results in hypersensitivity to aphidicolin, a DNA polymerase inhibitor that causes replication stress. We observed that the SNM1B nuclease is required for efficient localization of the DNA repair proteins, FANCD2 and BRCA1, to subnuclear foci upon aphidicolin treatment, thereby indicating SNM1B facilitates direct repair of stalled forks. Consistent with a role for SNM1B subsequent to recognition of the lesion, we found that SNM1B is dispensable for upstream events, including activation of ATR-dependent signaling and localization of RPA, γH2AX and the MRE11/RAD50/NBS1 complex to aphidicolin-induced foci. We determined that a major consequence of SNM1B depletion is a marked increase in spontaneous and aphidicolin-induced chromosomal gaps and breaks, including breakage at common fragile sites. Thus, this study provides evidence that SNM1B functions in resolving replication stress and preventing accumulation of genomic damage.
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44
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Nickoloff JA. Assaying DNA double-strand break induction and repair as fast as a speeding comet. Cell Cycle 2013; 12:1335-6. [PMID: 23588073 PMCID: PMC3674058 DOI: 10.4161/cc.24667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Jac A Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA.
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45
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Lu X, Parvathaneni S, Hara T, Lal A, Sharma S. Replication stress induces specific enrichment of RECQ1 at common fragile sites FRA3B and FRA16D. Mol Cancer 2013; 12:29. [PMID: 23601052 PMCID: PMC3663727 DOI: 10.1186/1476-4598-12-29] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 04/10/2013] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Stalled replication forks at common fragile sites are a major cause of genomic instability. RecQ helicases, a highly conserved family of DNA-unwinding enzymes, are believed to ease 'roadblocks' that pose challenge to replication fork progression. Among the five known RecQ homologs in humans, functions of RECQ1, the most abundant of all, are poorly understood. We previously determined that RECQ1 helicase preferentially binds and unwinds substrates that mimic DNA replication/repair intermediates, and interacts with proteins involved in DNA replication restart mechanisms. METHOD We have utilized chromatin immunoprecipitation followed by quantitative real-time PCR to investigate chromatin interactions of RECQ1 at defined genetic loci in the presence or absence of replication stress. We have also tested the sensitivity of RECQ1-depleted cells to aphidicolin induced replication stress. RESULTS RECQ1 binds to the origins of replication in unperturbed cells. We now show that conditions of replication stress induce increased accumulation of RECQ1 at the lamin B2 origin in HeLa cells. Consistent with a role in promoting fork recovery or repair, RECQ1 is specifically enriched at two major fragile sites FRA3B and FRA16D where replication forks have stalled following aphidicolin treatment. RECQ1-depletion results in attenuated checkpoint activation in response to replication stress, increased sensitivity to aphidicolin and chromosomal instability. CONCLUSIONS Given a recent biochemical observation that RECQ1 catalyzes strand exchange on stalled replication fork structures in vitro, our results indicate that RECQ1 facilitates repair of stalled or collapsed replication forks and preserves genome integrity. Our findings provide the first evidence of a crucial role for RECQ1 at naturally occurring fork stalling sites and implicate RECQ1 in mechanisms underlying common fragile site instability in cancer.
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Affiliation(s)
- Xing Lu
- Department of Biochemistry and Molecular Biology, College of Medicine, Howard University, 520 W Street, NW, Washington, DC 20059, USA. 2Genetics Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Swetha Parvathaneni
- Department of Biochemistry and Molecular Biology, College of Medicine, Howard University, 520 W Street, NW, Washington, DC 20059, USA. 2Genetics Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Toshifumi Hara
- Genetics Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Ashish Lal
- Genetics Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Sudha Sharma
- Department of Biochemistry and Molecular Biology, College of Medicine, Howard University, 520 W Street, NW, Washington, DC 20059, USA. 2Genetics Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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46
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Lambert S, Carr AM. Impediments to replication fork movement: stabilisation, reactivation and genome instability. Chromosoma 2013; 122:33-45. [DOI: 10.1007/s00412-013-0398-9] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 02/11/2013] [Accepted: 02/11/2013] [Indexed: 01/02/2023]
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47
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Zanellato I, Bonarrigo I, Gabano E, Ravera M, Margiotta N, Betta PG, Osella D. Metallo-drugs in the treatment of malignant pleural mesothelioma. Inorganica Chim Acta 2012. [DOI: 10.1016/j.ica.2012.06.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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48
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DVC1 (C1orf124) is a DNA damage-targeting p97 adaptor that promotes ubiquitin-dependent responses to replication blocks. Nat Struct Mol Biol 2012; 19:1084-92. [PMID: 23042605 DOI: 10.1038/nsmb.2395] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 08/30/2012] [Indexed: 12/17/2022]
Abstract
Ubiquitin-mediated processes orchestrate critical DNA-damage signaling and repair pathways. We identify human DVC1 (C1orf124; Spartan) as a cell cycle-regulated anaphase-promoting complex (APC) substrate that accumulates at stalled replication forks. DVC1 recruitment to sites of replication stress requires its ubiquitin-binding UBZ domain and PCNA-binding PIP box motif but is independent of RAD18-mediated PCNA monoubiquitylation. Via a conserved SHP box, DVC1 recruits the ubiquitin-selective chaperone p97 to blocked replication forks, which may facilitate p97-dependent removal of translesion synthesis (TLS) DNA polymerase η (Pol η) from monoubiquitylated PCNA. DVC1 knockdown enhances UV light-induced mutagenesis, and depletion of human DVC1 or the Caenorhabditis elegans ortholog DVC-1 causes hypersensitivity to replication stress-inducing agents. Our findings establish DVC1 as a DNA damage-targeting p97 adaptor that protects cells from deleterious consequences of replication blocks and suggest an important role of p97 in ubiquitin-dependent regulation of TLS.
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49
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Liu S, Opiyo SO, Manthey K, Glanzer JG, Ashley AK, Amerin C, Troksa K, Shrivastav M, Nickoloff JA, Oakley GG. Distinct roles for DNA-PK, ATM and ATR in RPA phosphorylation and checkpoint activation in response to replication stress. Nucleic Acids Res 2012; 40:10780-94. [PMID: 22977173 PMCID: PMC3510507 DOI: 10.1093/nar/gks849] [Citation(s) in RCA: 192] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
DNA damage encountered by DNA replication forks poses risks of genome destabilization, a
precursor to carcinogenesis. Damage checkpoint systems cause cell cycle arrest, promote
repair and induce programed cell death when damage is severe. Checkpoints are critical
parts of the DNA damage response network that act to suppress cancer. DNA damage and
perturbation of replication machinery causes replication stress, characterized by
accumulation of single-stranded DNA bound by replication protein A (RPA), which triggers
activation of ataxia telangiectasia and Rad3 related (ATR) and phosphorylation of the
RPA32, subunit of RPA, leading to Chk1 activation and arrest. DNA-dependent protein kinase
catalytic subunit (DNA-PKcs) [a kinase related to ataxia telangiectasia mutated (ATM) and
ATR] has well characterized roles in DNA double-strand break repair, but poorly understood
roles in replication stress-induced RPA phosphorylation. We show that DNA-PKcs mutant
cells fail to arrest replication following stress, and mutations in RPA32 phosphorylation
sites targeted by DNA-PKcs increase the proportion of cells in mitosis, impair ATR
signaling to Chk1 and confer a G2/M arrest defect. Inhibition of ATR and DNA-PK (but not
ATM), mimic the defects observed in cells expressing mutant RPA32. Cells expressing mutant
RPA32 or DNA-PKcs show sustained H2AX phosphorylation in response to replication stress
that persists in cells entering mitosis, indicating inappropriate mitotic entry with
unrepaired damage.
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Affiliation(s)
- Shengqin Liu
- Department of Oral Biology, University of Nebraska Medical Center, Omaha, NE 68583, USA
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50
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Kolesar P, Sarangi P, Altmannova V, Zhao X, Krejci L. Dual roles of the SUMO-interacting motif in the regulation of Srs2 sumoylation. Nucleic Acids Res 2012; 40:7831-43. [PMID: 22705796 PMCID: PMC3439891 DOI: 10.1093/nar/gks484] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Srs2 DNA helicase of Saccharomyces cerevisiae affects recombination in multiple ways. Srs2 not only inhibits recombination at stalled replication forks but also promotes the synthesis-dependent strand annealing (SDSA) pathway of recombination. Both functions of Srs2 are regulated by sumoylation--sumoylated PCNA recruits Srs2 to the replication fork to disfavor recombination, and sumoylation of Srs2 can be inhibitory to SDSA in certain backgrounds. To understand Srs2 function, we characterize the mechanism of its sumoylation in vitro and in vivo. Our data show that Srs2 is sumoylated at three lysines, and its sumoylation is facilitated by the Siz SUMO ligases. We also show that Srs2 binds to SUMO via a C-terminal SUMO-interacting motif (SIM). The SIM region is required for Srs2 sumoylation, likely by binding to SUMO-charged Ubc9. Srs2's SIM also cooperates with an adjacent PCNA-specific interaction site in binding to sumoylated PCNA to ensure the specificity of the interaction. These two functions of Srs2's SIM exhibit a competitive relationship: sumoylation of Srs2 decreases the interaction between the SIM and SUMO-PCNA, and the SUMO-PCNA-SIM interaction disfavors Srs2 sumoylation. Our findings suggest a potential mechanism for the equilibrium of sumoylated and PCNA-bound pools of Srs2 in cells.
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Affiliation(s)
- Peter Kolesar
- Department of Biology, National Centre for Biomolecular Research, Masaryk University, 62500 Brno, Czech Republic
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