1
|
Németh E, Szüts D. The mutagenic consequences of defective DNA repair. DNA Repair (Amst) 2024; 139:103694. [PMID: 38788323 DOI: 10.1016/j.dnarep.2024.103694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/10/2024] [Accepted: 05/14/2024] [Indexed: 05/26/2024]
Abstract
Multiple separate repair mechanisms safeguard the genome against various types of DNA damage, and their failure can increase the rate of spontaneous mutagenesis. The malfunction of distinct repair mechanisms leads to genomic instability through different mutagenic processes. For example, defective mismatch repair causes high base substitution rates and microsatellite instability, whereas homologous recombination deficiency is characteristically associated with deletions and chromosome instability. This review presents a comprehensive collection of all mutagenic phenotypes associated with the loss of each DNA repair mechanism, drawing on data from a variety of model organisms and mutagenesis assays, and placing greatest emphasis on systematic analyses of human cancer datasets. We describe the latest theories on the mechanism of each mutagenic process, often explained by reliance on an alternative repair pathway or the error-prone replication of unrepaired, damaged DNA. Aided by the concept of mutational signatures, the genomic phenotypes can be used in cancer diagnosis to identify defective DNA repair pathways.
Collapse
Affiliation(s)
- Eszter Németh
- Institute of Molecular Life Sciences, HUN-REN Research Centre for Natural Sciences, Budapest, Hungary
| | - Dávid Szüts
- Institute of Molecular Life Sciences, HUN-REN Research Centre for Natural Sciences, Budapest, Hungary.
| |
Collapse
|
2
|
Wang C, Chen Z, Su D, Tang M, Nie L, Zhang H, Feng X, Wang R, Shen X, Srivastava M, McLaughlin ME, Hart T, Li L, Chen J. C17orf53 is identified as a novel gene involved in inter-strand crosslink repair. DNA Repair (Amst) 2020; 95:102946. [PMID: 32853826 DOI: 10.1016/j.dnarep.2020.102946] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 07/22/2020] [Accepted: 07/31/2020] [Indexed: 01/05/2023]
Abstract
Ataxia Telangiectasia and Rad3-Related kinase (ATR) is a master regulator of genome maintenance, and participates in DNA replication and various DNA repair pathways. In a genome-wide screen for ATR-dependent fitness genes, we identified a previously uncharacterized gene, C17orf53, whose loss led to hypersensitivity to ATR inhibition. C17orf53 is conserved in vertebrates and is required for efficient cell proliferation. Loss of C17orf53 slowed down DNA replication and led to pronounced interstrand crosslink (ICL) repair defect. We showed that C17orf53 is a ssDNA- and RPA-binding protein and both characteristics are important for its functions in the cell. In addition, using multiple omics methods, we found that C17orf53 works with MCM8/9 to promote cell survival in response to ICL lesions. Taken together, our data suggest that C17orf53 is a novel component involved in ICL repair pathway.
Collapse
Affiliation(s)
- Chao Wang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Zhen Chen
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Dan Su
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Mengfan Tang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Litong Nie
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Huimin Zhang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Xu Feng
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Rui Wang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Xi Shen
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Mrinal Srivastava
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Megan E McLaughlin
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Traver Hart
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Lei Li
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Junjie Chen
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
| |
Collapse
|
3
|
Zhang H, Chen Z, Ye Y, Ye Z, Cao D, Xiong Y, Srivastava M, Feng X, Tang M, Wang C, Tainer JA, Chen J. SLX4IP acts with SLX4 and XPF-ERCC1 to promote interstrand crosslink repair. Nucleic Acids Res 2019; 47:10181-10201. [PMID: 31495888 PMCID: PMC6821277 DOI: 10.1093/nar/gkz769] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 08/03/2019] [Accepted: 09/05/2019] [Indexed: 12/13/2022] Open
Abstract
Interstrand crosslinks (ICLs) are highly toxic DNA lesions that are repaired via a complex process requiring the coordination of several DNA repair pathways. Defects in ICL repair result in Fanconi anemia, which is characterized by bone marrow failure, developmental abnormalities, and a high incidence of malignancies. SLX4, also known as FANCP, acts as a scaffold protein and coordinates multiple endonucleases that unhook ICLs, resolve homologous recombination intermediates, and perhaps remove unhooked ICLs. In this study, we explored the role of SLX4IP, a constitutive factor in the SLX4 complex, in ICL repair. We found that SLX4IP is a novel regulatory factor; its depletion sensitized cells to treatment with ICL-inducing agents and led to accumulation of cells in the G2/M phase. We further discovered that SLX4IP binds to SLX4 and XPF-ERCC1 simultaneously and that disruption of one interaction also disrupts the other. The binding of SLX4IP to both SLX4 and XPF-ERCC1 not only is vital for maintaining the stability of SLX4IP protein, but also promotes the interaction between SLX4 and XPF-ERCC1, especially after DNA damage. Collectively, these results demonstrate a new regulatory role for SLX4IP in maintaining an efficient SLX4-XPF-ERCC1 complex in ICL repair.
Collapse
Affiliation(s)
- Huimin Zhang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Zhen Chen
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yin Ye
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Zu Ye
- Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
| | - Dan Cao
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yun Xiong
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Mrinal Srivastava
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Xu Feng
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Mengfan Tang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Chao Wang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - John A Tainer
- Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
| | - Junjie Chen
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| |
Collapse
|
4
|
Buzon B, Grainger R, Huang S, Rzadki C, Junop MS. Structure-specific endonuclease activity of SNM1A enables processing of a DNA interstrand crosslink. Nucleic Acids Res 2019; 46:9057-9066. [PMID: 30165656 PMCID: PMC6158701 DOI: 10.1093/nar/gky759] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 08/20/2018] [Indexed: 01/09/2023] Open
Abstract
DNA interstrand crosslinks (ICLs) covalently join opposing strands, blocking both replication and transcription, therefore making ICL-inducing compounds highly toxic and ideal anti-cancer agents. While incisions surrounding the ICL are required to remove damaged DNA, it is currently unclear which endonucleases are needed for this key event. SNM1A has been shown to play an important function in human ICL repair, however its suggested role has been limited to exonuclease activity and not strand incision. Here we show that SNM1A has endonuclease activity, having the ability to cleave DNA structures that arise during the initiation of ICL repair. In particular, this endonuclease activity cleaves single-stranded DNA. Given that unpaired DNA regions occur 5′ to an ICL, these findings suggest SNM1A may act as either an endonuclease and/or exonuclease during ICL repair. This finding is significant as it expands the potential role of SNM1A in ICL repair.
Collapse
Affiliation(s)
- Beverlee Buzon
- Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster, University, Hamilton, Ontario L8N 3Z5, Canada.,Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, Ontario N6A 5C1, Canada
| | - Ryan Grainger
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, Ontario N6A 5C1, Canada
| | - Simon Huang
- Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster, University, Hamilton, Ontario L8N 3Z5, Canada
| | - Cameron Rzadki
- Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster, University, Hamilton, Ontario L8N 3Z5, Canada
| | - Murray S Junop
- Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster, University, Hamilton, Ontario L8N 3Z5, Canada.,Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, Ontario N6A 5C1, Canada
| |
Collapse
|
5
|
Chernikova SB, Nguyen RB, Truong JT, Mello SS, Stafford JH, Hay MP, Olson A, Solow-Cordero DE, Wood DJ, Henry S, von Eyben R, Deng L, Gephart MH, Aroumougame A, Wiese C, Game JC, Győrffy B, Brown JM. Dynamin impacts homology-directed repair and breast cancer response to chemotherapy. J Clin Invest 2018; 128:5307-5321. [PMID: 30371505 DOI: 10.1172/jci87191] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 09/13/2018] [Indexed: 12/31/2022] Open
Abstract
After the initial responsiveness of triple-negative breast cancers (TNBCs) to chemotherapy, they often recur as chemotherapy-resistant tumors, and this has been associated with upregulated homology-directed repair (HDR). Thus, inhibitors of HDR could be a useful adjunct to chemotherapy treatment of these cancers. We performed a high-throughput chemical screen for inhibitors of HDR from which we obtained a number of hits that disrupted microtubule dynamics. We postulated that high levels of the target molecules of our screen in tumors would correlate with poor chemotherapy response. We found that inhibition or knockdown of dynamin 2 (DNM2), known for its role in endocytic cell trafficking and microtubule dynamics, impaired HDR and improved response to chemotherapy of cells and of tumors in mice. In a retrospective analysis, levels of DNM2 at the time of treatment strongly predicted chemotherapy outcome for estrogen receptor-negative and especially for TNBC patients. We propose that DNM2-associated DNA repair enzyme trafficking is important for HDR efficiency and is a powerful predictor of sensitivity to breast cancer chemotherapy and an important target for therapy.
Collapse
Affiliation(s)
- Sophia B Chernikova
- Department of Radiation Oncology, Stanford University, Stanford, California, USA
| | - Rochelle B Nguyen
- Department of Radiation Oncology, Stanford University, Stanford, California, USA
| | - Jessica T Truong
- Department of Radiation Oncology, Stanford University, Stanford, California, USA
| | - Stephano S Mello
- Department of Radiation Oncology, Stanford University, Stanford, California, USA
| | - Jason H Stafford
- Department of Radiation Oncology, Stanford University, Stanford, California, USA
| | - Michael P Hay
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | | | | | - Douglas J Wood
- Data Coordinating Center, Department of Biomedical Data Science, and
| | - Solomon Henry
- Data Coordinating Center, Department of Biomedical Data Science, and
| | - Rie von Eyben
- Department of Radiation Oncology, Stanford University, Stanford, California, USA
| | - Lei Deng
- Department of Radiation Oncology, Stanford University, Stanford, California, USA
| | | | - Asaithamby Aroumougame
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Claudia Wiese
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, USA
| | - John C Game
- Department of Radiation Oncology, Stanford University, Stanford, California, USA
| | - Balázs Győrffy
- MTA TTK Lendület Cancer Biomarker Research Group, Institute of Enzymology, Budapest, Hungary.,Semmelweis University 2nd Department of Pediatrics, Budapest, Hungary
| | - J Martin Brown
- Department of Radiation Oncology, Stanford University, Stanford, California, USA
| |
Collapse
|
6
|
Shen CY, Chen LH, Lin YF, Lai LC, Chuang EY, Tsai MH. Mitomycin C treatment induces resistance and enhanced migration via phosphorylated Akt in aggressive lung cancer cells. Oncotarget 2018; 7:79995-80007. [PMID: 27833080 PMCID: PMC5346766 DOI: 10.18632/oncotarget.13237] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 10/22/2016] [Indexed: 01/07/2023] Open
Abstract
Since 1984, mitomycin C (MMC) has been applied in the treatment of non-small-cell lung cancer (NSCLC). MMC-based chemotherapeutic regimens are still under consideration owing to the efficacy and low cost as compared with other second-line regimens in patients with advanced NSCLC. Hence, it is important to investigate whether MMC induces potential negative effects in NSCLC. Here, we found that the malignant lung cancer cells, CL1-2 and CL1-5, were more resistant to MMC than were the parental CL1-0 cells and pre-malignant CL1-1 cells. CL1-2 and CL1-5 cells consistently showed lower sub-G1 fractions post MMC treatment. DNA repair-related proteins were not induced more in CL1-5 than in CL1-0 cells, but the levels of endogenous and MMC-induced phosphorylated Akt (p-Akt) were higher in CL1-5 cells. Administering a p-Akt inhibitor reduced the MMC resistance, demonstrating that p-Akt is important in the MMC resistance of CL1-5 cells. Furthermore, we revealed that cell migration was enhanced by MMC but lowered by a p-Akt inhibitor in CL1-5 cells. This study suggests that in CL1-5 cells, the activity of p-Akt, rather than DNA repair mechanisms, may underlie the resistance to MMC and enhance the cells' migration abilities after MMC treatment.
Collapse
Affiliation(s)
- Cheng-Ying Shen
- Institute of Biotechnology, National Taiwan University, Taipei, Taiwan
| | - Li-Han Chen
- YongLin Biomedical Engineering Center, National Taiwan University, Taipei, Taiwan
| | - Yu-Fen Lin
- YongLin Biomedical Engineering Center, National Taiwan University, Taipei, Taiwan.,Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Liang-Chuan Lai
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan
| | - Eric Y Chuang
- YongLin Biomedical Engineering Center, National Taiwan University, Taipei, Taiwan.,Genome and Systems Biology Degree Program, National Taiwan University, Taipei, Taiwan.,Bioinformatics and Biostatistics Core, Center of Genomic Medicine, National Taiwan University, Taipei, Taiwan.,Center for Biotechnology, National Taiwan University, Taipei, Taiwan.,Institute of Epidemiology and Preventive Medicine, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Chinese Medical Science, China Medical University, Taichung, Taiwan.,Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan
| | - Mong-Hsun Tsai
- Institute of Biotechnology, National Taiwan University, Taipei, Taiwan.,Genome and Systems Biology Degree Program, National Taiwan University, Taipei, Taiwan.,Bioinformatics and Biostatistics Core, Center of Genomic Medicine, National Taiwan University, Taipei, Taiwan.,Center for Biotechnology, National Taiwan University, Taipei, Taiwan.,Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan University, Taipei, Taiwan
| |
Collapse
|
7
|
Ranjha L, Howard SM, Cejka P. Main steps in DNA double-strand break repair: an introduction to homologous recombination and related processes. Chromosoma 2018; 127:187-214. [PMID: 29327130 DOI: 10.1007/s00412-017-0658-1] [Citation(s) in RCA: 209] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 12/15/2017] [Accepted: 12/19/2017] [Indexed: 12/16/2022]
Abstract
DNA double-strand breaks arise accidentally upon exposure of DNA to radiation and chemicals or result from faulty DNA metabolic processes. DNA breaks can also be introduced in a programmed manner, such as during the maturation of the immune system, meiosis, or cancer chemo- or radiotherapy. Cells have developed a variety of repair pathways, which are fine-tuned to the specific needs of a cell. Accordingly, vegetative cells employ mechanisms that restore the integrity of broken DNA with the highest efficiency at the lowest cost of mutagenesis. In contrast, meiotic cells or developing lymphocytes exploit DNA breakage to generate diversity. Here, we review the main pathways of eukaryotic DNA double-strand break repair with the focus on homologous recombination and its various subpathways. We highlight the differences between homologous recombination and end-joining mechanisms including non-homologous end-joining and microhomology-mediated end-joining and offer insights into how these pathways are regulated. Finally, we introduce noncanonical functions of the recombination proteins, in particular during DNA replication stress.
Collapse
Affiliation(s)
- Lepakshi Ranjha
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | - Sean M Howard
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland. .,Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland.
| |
Collapse
|
8
|
Wilson DM, Rieckher M, Williams AB, Schumacher B. Systematic analysis of DNA crosslink repair pathways during development and aging in Caenorhabditis elegans. Nucleic Acids Res 2017; 45:9467-9480. [PMID: 28934497 PMCID: PMC5766164 DOI: 10.1093/nar/gkx660] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 07/18/2017] [Indexed: 01/12/2023] Open
Abstract
DNA interstrand crosslinks (ICLs) are generated by endogenous sources and chemotherapeutics, and pose a threat to genome stability and cell survival. Using Caenorhabditis elegans mutants, we identify DNA repair factors that protect against the genotoxicity of ICLs generated by trioxsalen/ultraviolet A (TMP/UVA) during development and aging. Mutations in nucleotide excision repair (NER) components (e.g. XPA-1 and XPF-1) imparted extreme sensitivity to TMP/UVA relative to wild-type animals, manifested as developmental arrest, defects in adult tissue morphology and functionality, and shortened lifespan. Compensatory roles for global-genome (XPC-1) and transcription-coupled (CSB-1) NER in ICL sensing were exposed. The analysis also revealed contributions of homologous recombination (BRC-1/BRCA1), the MUS-81, EXO-1, SLX-1 and FAN-1 nucleases, and the DOG-1 (FANCJ) helicase in ICL resolution, influenced by the replicative-status of the cell/tissue. No obvious or critical role in ICL repair was seen for non-homologous end-joining (cku-80) or base excision repair (nth-1, exo-3), the Fanconi-related proteins BRC-2 (BRCA2/FANCD1) and FCD-2 (FANCD2), the WRN-1 or HIM-6 (BLM) helicases, or the GEN-1 or MRT-1 (SNM1) nucleases. Our efforts uncover replication-dependent and -independent ICL repair networks, and establish nematodes as a model for investigating the repair and consequences of DNA crosslinks in metazoan development and in adult post-mitotic and proliferative germ cells.
Collapse
Affiliation(s)
- David M Wilson
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Matthias Rieckher
- Institute for Genome Stability in Aging and Disease, Medical Faculty, Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), Center for Molecular Medicine Cologne (CMMC) and Systems Biology of Ageing Cologne (Sybacol), University of Cologne, Joseph-Stelzmann-Strasse 26, 50931 Cologne, Germany
| | - Ashley B Williams
- Institute for Genome Stability in Aging and Disease, Medical Faculty, Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), Center for Molecular Medicine Cologne (CMMC) and Systems Biology of Ageing Cologne (Sybacol), University of Cologne, Joseph-Stelzmann-Strasse 26, 50931 Cologne, Germany
| | - Björn Schumacher
- Institute for Genome Stability in Aging and Disease, Medical Faculty, Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), Center for Molecular Medicine Cologne (CMMC) and Systems Biology of Ageing Cologne (Sybacol), University of Cologne, Joseph-Stelzmann-Strasse 26, 50931 Cologne, Germany
| |
Collapse
|
9
|
Yang Z, Nejad MI, Varela JG, Price NE, Wang Y, Gates KS. A role for the base excision repair enzyme NEIL3 in replication-dependent repair of interstrand DNA cross-links derived from psoralen and abasic sites. DNA Repair (Amst) 2017; 52:1-11. [PMID: 28262582 PMCID: PMC5424475 DOI: 10.1016/j.dnarep.2017.02.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 02/13/2017] [Indexed: 12/23/2022]
Abstract
Interstrand DNA-DNA cross-links are highly toxic lesions that are important in medicinal chemistry, toxicology, and endogenous biology. In current models of replication-dependent repair, stalling of a replication fork activates the Fanconi anemia pathway and cross-links are "unhooked" by the action of structure-specific endonucleases such as XPF-ERCC1 that make incisions flanking the cross-link. This process generates a double-strand break, which must be subsequently repaired by homologous recombination. Recent work provided evidence for a new, incision-independent unhooking mechanism involving intrusion of a base excision repair (BER) enzyme, NEIL3, into the world of cross-link repair. The evidence suggests that the glycosylase action of NEIL3 unhooks interstrand cross-links derived from an abasic site or the psoralen derivative trioxsalen. If the incision-independent NEIL3 pathway is blocked, repair reverts to the incision-dependent route. In light of the new model invoking participation of NEIL3 in cross-link repair, we consider the possibility that various BER glycosylases or other DNA-processing enzymes might participate in the unhooking of chemically diverse interstrand DNA cross-links.
Collapse
Affiliation(s)
- Zhiyu Yang
- University of Missouri Department of Chemistry, 125 Chemistry Building Columbia, MO 65211, United States
| | - Maryam Imani Nejad
- University of Missouri Department of Chemistry, 125 Chemistry Building Columbia, MO 65211, United States
| | - Jacqueline Gamboa Varela
- University of Missouri Department of Chemistry, 125 Chemistry Building Columbia, MO 65211, United States
| | - Nathan E Price
- University of California-Riverside, Department of Chemistry, 501 Big Springs Road Riverside, CA 92521-0403, United States
| | - Yinsheng Wang
- University of California-Riverside, Department of Chemistry, 501 Big Springs Road Riverside, CA 92521-0403, United States
| | - Kent S Gates
- University of Missouri Department of Chemistry, 125 Chemistry Building Columbia, MO 65211, United States; University of Missouri Department of Biochemistry, 125 Chemistry Building Columbia, MO 65211, United States.
| |
Collapse
|
10
|
Shuttling along DNA and directed processing of D-loops by RecQ helicase support quality control of homologous recombination. Proc Natl Acad Sci U S A 2017; 114:E466-E475. [PMID: 28069956 DOI: 10.1073/pnas.1615439114] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cells must continuously repair inevitable DNA damage while avoiding the deleterious consequences of imprecise repair. Distinction between legitimate and illegitimate repair processes is thought to be achieved in part through differential recognition and processing of specific noncanonical DNA structures, although the mechanistic basis of discrimination remains poorly defined. Here, we show that Escherichia coli RecQ, a central DNA recombination and repair enzyme, exhibits differential processing of DNA substrates based on their geometry and structure. Through single-molecule and ensemble biophysical experiments, we elucidate how the conserved domain architecture of RecQ supports geometry-dependent shuttling and directed processing of recombination-intermediate [displacement loop (D-loop)] substrates. Our study shows that these activities together suppress illegitimate recombination in vivo, whereas unregulated duplex unwinding is detrimental for recombination precision. Based on these results, we propose a mechanism through which RecQ helicases achieve recombination precision and efficiency.
Collapse
|
11
|
Lai TH, Ewald B, Zecevic A, Liu C, Sulda M, Papaioannou D, Garzon R, Blachly JS, Plunkett W, Sampath D. HDAC Inhibition Induces MicroRNA-182, which Targets RAD51 and Impairs HR Repair to Sensitize Cells to Sapacitabine in Acute Myelogenous Leukemia. Clin Cancer Res 2016; 22:3537-49. [PMID: 26858310 DOI: 10.1158/1078-0432.ccr-15-1063] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Accepted: 01/27/2016] [Indexed: 12/31/2022]
Abstract
PURPOSE The double-strand breaks elicited by sapacitabine, a clinically active nucleoside analogue prodrug, are repaired by RAD51 and the homologous recombination repair (HR) pathway, which could potentially limit its toxicity. We investigated the mechanism by which histone deacetylase (HDAC) inhibitors targeted RAD51 and HR to sensitize acute myelogenous leukemia (AML) cells to sapacitabine. EXPERIMENTAL DESIGN Chromatin immunoprecipitation identified the role of HDACs in silencing miR-182 in AML. Immunoblotting, gene expression, overexpression, or inhibition of miR-182 and luciferase assays established that miR-182 directly targeted RAD51. HR reporter assays, apoptotic assays, and colony-forming assays established that the miR-182, as well as the HDAC inhibition-mediated decreases in RAD51 inhibited HR repair and sensitized cells to sapacitabine. RESULTS The gene repressors, HDAC1 and HDAC2, became recruited to the promoter of miR-182 to silence its expression in AML. HDAC inhibition induced miR-182 in AML cell lines and primary AML blasts. miR-182 targeted RAD51 protein both in luciferase assays and in AML cells. Overexpression of miR-182, as well as HDAC inhibition-mediated induction of miR-182 were linked to time- and dose-dependent decreases in the levels of RAD51, an inhibition of HR, increased levels of residual damage, and decreased survival after exposure to double-strand damage-inducing agents. CONCLUSIONS Our findings define the mechanism by which HDAC inhibition induces miR-182 to target RAD51 and highlights a novel pharmacologic strategy that compromises the ability of AML cells to conduct HR, thereby sensitizing AML cells to DNA-damaging agents that activate HR as a repair and potential resistance mechanism. Clin Cancer Res; 22(14); 3537-49. ©2016 AACR.
Collapse
Affiliation(s)
- Tsung-Huei Lai
- Division of Hematology, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio
| | - Brett Ewald
- Department of Experimental Therapeutics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Alma Zecevic
- Department of Experimental Therapeutics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Chaomei Liu
- Department of Experimental Therapeutics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Melanie Sulda
- Department of Experimental Therapeutics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Dimitrios Papaioannou
- Division of Hematology, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio
| | - Ramiro Garzon
- Division of Hematology, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio
| | - James S Blachly
- Division of Hematology, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio
| | - William Plunkett
- Department of Experimental Therapeutics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas.
| | - Deepa Sampath
- Division of Hematology, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio.
| |
Collapse
|
12
|
Weaver AN, Cooper TS, Rodriguez M, Trummell HQ, Bonner JA, Rosenthal EL, Yang ES. DNA double strand break repair defect and sensitivity to poly ADP-ribose polymerase (PARP) inhibition in human papillomavirus 16-positive head and neck squamous cell carcinoma. Oncotarget 2015; 6:26995-7007. [PMID: 26336991 PMCID: PMC4694969 DOI: 10.18632/oncotarget.4863] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 08/12/2015] [Indexed: 01/04/2023] Open
Abstract
Patients with human papillomavirus-positive (HPV+) head and neck squamous cell carcinomas (HNSCCs) have increased response to radio- and chemotherapy and improved overall survival, possibly due to an impaired DNA damage response. Here, we investigated the correlation between HPV status and repair of DNA damage in HNSCC cell lines. We also assessed in vitro and in vivo sensitivity to the PARP inhibitor veliparib (ABT-888) in HNSCC cell lines and an HPV+ patient xenograft. Repair of DNA double strand breaks (DSBs) was significantly delayed in HPV+ compared to HPV- HNSCCs, resulting in persistence of γH2AX foci. Although DNA repair activators 53BP1 and BRCA1 were functional in all HNSCCs, HPV+ cells showed downstream defects in both non-homologous end joining and homologous recombination repair. Specifically, HPV+ cells were deficient in protein recruitment and protein expression of DNA-Pk and BRCA2, key factors for non-homologous end joining and homologous recombination respectively. Importantly, the apparent DNA repair defect in HPV+ HNSCCs was associated with increased sensitivity to the PARP inhibitor veliparib, resulting in decreased cell survival in vitro and a 10-14 day tumor growth delay in vivo. These results support the testing of PARP inhibition in combination with DNA damaging agents as a novel therapeutic strategy for HPV+ HNSCC.
Collapse
Affiliation(s)
- Alice N. Weaver
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
| | - Tiffiny S. Cooper
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
| | - Marcela Rodriguez
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
| | - Hoa Q. Trummell
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
| | - James A. Bonner
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
| | - Eben L. Rosenthal
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL 35249, USA
| | - Eddy S. Yang
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
| |
Collapse
|
13
|
Pizzolato J, Mukherjee S, Schärer OD, Jiricny J. FANCD2-associated nuclease 1, but not exonuclease 1 or flap endonuclease 1, is able to unhook DNA interstrand cross-links in vitro. J Biol Chem 2015. [PMID: 26221031 DOI: 10.1074/jbc.m115.663666] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cisplatin and its derivatives, nitrogen mustards and mitomycin C, are used widely in cancer chemotherapy. Their efficacy is linked primarily to their ability to generate DNA interstrand cross-links (ICLs), which effectively block the progression of transcription and replication machineries. Release of this block, referred to as unhooking, has been postulated to require endonucleases that incise one strand of the duplex on either side of the ICL. Here we investigated how the 5' flap nucleases FANCD2-associated nuclease 1 (FAN1), exonuclease 1 (EXO1), and flap endonuclease 1 (FEN1) process a substrate reminiscent of a replication fork arrested at an ICL. We now show that EXO1 and FEN1 cleaved the substrate at the boundary between the single-stranded 5' flap and the duplex, whereas FAN1 incised it three to four nucleotides in the double-stranded region. This affected the outcome of processing of a substrate containing a nitrogen mustard-like ICL two nucleotides in the duplex region because FAN1, unlike EXO1 and FEN1, incised the substrate predominantly beyond the ICL and, therefore, failed to release the 5' flap. We also show that FAN1 was able to degrade a linear ICL substrate. This ability of FAN1 to traverse ICLs in DNA could help to elucidate its biological function, which is currently unknown.
Collapse
Affiliation(s)
- Julia Pizzolato
- From the Institute of Molecular Cancer Research, University of Zurich and
| | | | - Orlando D Schärer
- the Departments of Chemistry and Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794-3400
| | - Josef Jiricny
- From the Institute of Molecular Cancer Research, University of Zurich and the Department of Biology, Swiss Institute of Technology (ETH) Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland, and
| |
Collapse
|
14
|
Scala G, Affinito O, Miele G, Monticelli A, Cocozza S. Evidence for evolutionary and nonevolutionary forces shaping the distribution of human genetic variants near transcription start sites. PLoS One 2014; 9:e114432. [PMID: 25474578 PMCID: PMC4256220 DOI: 10.1371/journal.pone.0114432] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 11/09/2014] [Indexed: 11/19/2022] Open
Abstract
The regions surrounding transcription start sites (TSSs) of genes play a critical role in the regulation of gene expression. At the same time, current evidence indicates that these regions are particularly stressed by transcription-related mutagenic phenomena. In this work we performed a genome-wide analysis of the distribution of single nucleotide polymorphisms (SNPs) inside the 10 kb region flanking human TSSs by dividing SNPs into four classes according to their frequency (rare, two intermediate classes, and common). We found that, in this 10 kb region, the distribution of variants depends on their frequency and on their localization relative to the TSS. We found that the distribution of variants is generally different for TSSs located inside or outside of CpG islands. We found a significant relationship between the distribution of rare variants and nucleosome occupancy scores. Furthermore, our analysis suggests that evolutionary (purifying selection) and nonevolutionary (biased gene conversion) forces both play a role in determining the relative SNP frequency around TSSs. Finally, we analyzed the potential pathogenicity of each class of variant using the Combined Annotation Dependent Depletion score. In conclusion, this study provides a novel and detailed view of the distribution of genomic variants around TSSs, providing insight into the forces that instigate and maintain variability in such critical regions.
Collapse
Affiliation(s)
- Giovanni Scala
- Gruppo Interdipartimentale di Bioinformatica e Biologia Computazionale, Università degli Studi di Napoli “Federico II”, Naples, Italy
- Dipartimento di Fisica, Università degli Studi di Napoli “Federico II”, Naples, Italy
- Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, Naples, Italy
- * E-mail:
| | - Ornella Affinito
- Gruppo Interdipartimentale di Bioinformatica e Biologia Computazionale, Università degli Studi di Napoli “Federico II”, Naples, Italy
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli “Federico II”, Naples, Italy
- Istituto di Endocrinologia ed Oncologia Sperimentale (IEOS), CNR, Naples, Italy
| | - Gennaro Miele
- Gruppo Interdipartimentale di Bioinformatica e Biologia Computazionale, Università degli Studi di Napoli “Federico II”, Naples, Italy
- Dipartimento di Fisica, Università degli Studi di Napoli “Federico II”, Naples, Italy
- Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, Naples, Italy
| | - Antonella Monticelli
- Gruppo Interdipartimentale di Bioinformatica e Biologia Computazionale, Università degli Studi di Napoli “Federico II”, Naples, Italy
- Istituto di Endocrinologia ed Oncologia Sperimentale (IEOS), CNR, Naples, Italy
| | - Sergio Cocozza
- Gruppo Interdipartimentale di Bioinformatica e Biologia Computazionale, Università degli Studi di Napoli “Federico II”, Naples, Italy
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli “Federico II”, Naples, Italy
| |
Collapse
|
15
|
Vidi PA, Liu J, Salles D, Jayaraman S, Dorfman G, Gray M, Abad P, Moghe PV, Irudayaraj JM, Wiesmüller L, Lelièvre SA. NuMA promotes homologous recombination repair by regulating the accumulation of the ISWI ATPase SNF2h at DNA breaks. Nucleic Acids Res 2014; 42:6365-79. [PMID: 24753406 PMCID: PMC4041463 DOI: 10.1093/nar/gku296] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Chromatin remodeling factors play an active role in the DNA damage response by shaping chromatin to facilitate the repair process. The spatiotemporal regulation of these factors is key to their function, yet poorly understood. We report that the structural nuclear protein NuMA accumulates at sites of DNA damage in a poly[ADP-ribose]ylation-dependent manner and functionally interacts with the ISWI ATPase SNF2h/SMARCA5, a chromatin remodeler that facilitates DNA repair. NuMA coimmunoprecipitates with SNF2h, regulates its diffusion in the nucleoplasm and controls its accumulation at DNA breaks. Consistent with NuMA enabling SNF2h function, cells with silenced NuMA exhibit reduced chromatin decompaction after DNA cleavage, lesser focal recruitment of homologous recombination repair factors, impaired DNA double-strand break repair in chromosomal (but not in episomal) contexts and increased sensitivity to DNA cross-linking agents. These findings reveal a structural basis for the orchestration of chromatin remodeling whereby a scaffold protein promotes genome maintenance by directing a remodeler to DNA breaks.
Collapse
Affiliation(s)
- Pierre-Alexandre Vidi
- Department of Basic Medical Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Jing Liu
- Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Daniela Salles
- Department of Obstetrics and Gynecology, University of Ulm, Prittwitzstrasse 43, D-89075 Ulm, Germany
| | - Swaathi Jayaraman
- Department of Basic Medical Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - George Dorfman
- Department of Biomedical Engineering, and Chemical & Biochemical Engineering, Rutgers University, Piscataway, NJ 08854, USA
| | - Matthew Gray
- Department of Basic Medical Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Patricia Abad
- Department of Basic Medical Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Prabhas V Moghe
- Department of Biomedical Engineering, and Chemical & Biochemical Engineering, Rutgers University, Piscataway, NJ 08854, USA
| | - Joseph M Irudayaraj
- Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907, USA Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - Lisa Wiesmüller
- Department of Obstetrics and Gynecology, University of Ulm, Prittwitzstrasse 43, D-89075 Ulm, Germany
| | - Sophie A Lelièvre
- Department of Basic Medical Sciences, Purdue University, West Lafayette, IN 47907, USA Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| |
Collapse
|
16
|
Inturi S, Tewari-Singh N, Agarwal C, White CW, Agarwal R. Activation of DNA damage repair pathways in response to nitrogen mustard-induced DNA damage and toxicity in skin keratinocytes. Mutat Res 2014; 763-764:53-63. [PMID: 24732344 DOI: 10.1016/j.mrfmmm.2014.04.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 03/18/2014] [Accepted: 04/03/2014] [Indexed: 01/24/2023]
Abstract
Nitrogen mustard (NM), a structural analog of chemical warfare agent sulfur mustard (SM), forms adducts and crosslinks with DNA, RNA and proteins. Here we studied the mechanism of NM-induced skin toxicity in response to double strand breaks (DSBs) resulting in cell cycle arrest to facilitate DNA repair, as a model for developing countermeasures against vesicant-induced skin injuries. NM exposure of mouse epidermal JB6 cells decreased cell growth and caused S-phase arrest. Consistent with these biological outcomes, NM exposure also increased comet tail extent moment and the levels of DNA DSB repair molecules phospho H2A.X Ser139 and p53 Ser15 indicating NM-induced DNA DSBs. Since DNA DSB repair occurs via non homologous end joining pathway (NHEJ) or homologous recombination repair (HRR) pathways, next we studied these two pathways and noted their activation as defined by an increase in phospho- and total DNA-PK levels, and the formation of Rad51 foci, respectively. To further analyze the role of these pathways in the cellular response to NM-induced cytotoxicity, NHEJ and HRR were inhibited by DNA-PK inhibitor NU7026 and Rad51 inhibitor BO2, respectively. Inhibition of NHEJ did not sensitize cells to NM-induced decrease in cell growth and cell cycle arrest. However, inhibition of the HRR pathway caused a significant increase in cell death, and prolonged G2M arrest following NM exposure. Together, our findings, indicating that HRR is the key pathway involved in the repair of NM-induced DNA DSBs, could be useful in developing new therapeutic strategies against vesicant-induced skin injury.
Collapse
Affiliation(s)
- Swetha Inturi
- Department of Pharmaceutical Sciences, University of Colorado Anchutz Medical Campus, Skaggs School of Pharmacy and Pharmaceutical Sciences, Aurora, CO 80045, USA
| | - Neera Tewari-Singh
- Department of Pharmaceutical Sciences, University of Colorado Anchutz Medical Campus, Skaggs School of Pharmacy and Pharmaceutical Sciences, Aurora, CO 80045, USA
| | - Chapla Agarwal
- Department of Pharmaceutical Sciences, University of Colorado Anchutz Medical Campus, Skaggs School of Pharmacy and Pharmaceutical Sciences, Aurora, CO 80045, USA
| | - Carl W White
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Rajesh Agarwal
- Department of Pharmaceutical Sciences, University of Colorado Anchutz Medical Campus, Skaggs School of Pharmacy and Pharmaceutical Sciences, Aurora, CO 80045, USA.
| |
Collapse
|
17
|
Saldanha SN, Tollefsbol TO. Pathway modulations and epigenetic alterations in ovarian tumorbiogenesis. J Cell Physiol 2014; 229:393-406. [PMID: 24105793 DOI: 10.1002/jcp.24466] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Accepted: 09/06/2013] [Indexed: 12/23/2022]
Abstract
Cellular pathways are numerous and are highly integrated in function in the control of cellular systems. They collectively regulate cell division, proliferation, survival and apoptosis of cells and mutagenesis of key genes that control these pathways can initiate neoplastic transformations. Understanding these pathways is crucial to future therapeutic and preventive strategies of the disease. Ovarian cancers are of three major types; epithelial, germ-cell, and stromal. However, ovarian cancers of epithelial origin, arising from the mesothelium, are the predominant form. Of the subtypes of ovarian cancer, the high-grade serous tumors are fatal, with low survival rate due to late detection and poor response to treatments. Close examination of preserved ovarian tissues and in vitro studies have provided insights into the mechanistic changes occurring in cells mediated by a few key genes. This review will focus on pathways and key genes of the pathways that are mutated or have aberrant functions in the pathology of ovarian cancer. Non-genetic mechanisms that are gaining prominence in the pathology of ovarian cancer, miRNAs and epigenetics, will also be discussed in the review.
Collapse
Affiliation(s)
- Sabita N Saldanha
- Department of Biology, University of Alabama at Birmingham, Birmingham, Alabama; Department of Biological Sciences, Alabama State University, Montgomery, Alabama
| | | |
Collapse
|
18
|
Abbotts R, Thompson N, Madhusudan S. DNA repair in cancer: emerging targets for personalized therapy. Cancer Manag Res 2014; 6:77-92. [PMID: 24600246 PMCID: PMC3933425 DOI: 10.2147/cmar.s50497] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Genomic deoxyribonucleic acid (DNA) is under constant threat from endogenous and exogenous DNA damaging agents. Mammalian cells have evolved highly conserved DNA repair machinery to process DNA damage and maintain genomic integrity. Impaired DNA repair is a major driver for carcinogenesis and could promote aggressive cancer biology. Interestingly, in established tumors, DNA repair activity is required to counteract oxidative DNA damage that is prevalent in the tumor microenvironment. Emerging clinical data provide compelling evidence that overexpression of DNA repair factors may have prognostic and predictive significance in patients. More recently, DNA repair inhibition has emerged as a promising target for anticancer therapy. Synthetic lethality exploits intergene relationships where the loss of function of either of two related genes is nonlethal, but loss of both causes cell death. Exploiting this approach by targeting DNA repair has emerged as a promising strategy for personalized cancer therapy. In the current review, we focus on recent advances with a particular focus on synthetic lethality targeting in cancer.
Collapse
Affiliation(s)
- Rachel Abbotts
- University of Nottingham, Academic Unit of Oncology, Division of Oncology, School of Medicine, Nottingham University Hospitals, City Hospital Campus, Nottingham, UK
| | - Nicola Thompson
- University of Nottingham, Academic Unit of Oncology, Division of Oncology, School of Medicine, Nottingham University Hospitals, City Hospital Campus, Nottingham, UK
| | - Srinivasan Madhusudan
- University of Nottingham, Academic Unit of Oncology, Division of Oncology, School of Medicine, Nottingham University Hospitals, City Hospital Campus, Nottingham, UK
| |
Collapse
|
19
|
Wu HC, Delgado-Cruzata L, Machella N, Wang Q, Santella RM, Terry MB. DNA double-strand break repair genotype and phenotype and breast cancer risk within sisters from the New York site of the Breast Cancer Family Registry (BCFR). Cancer Causes Control 2013; 24:2157-68. [PMID: 24062231 DOI: 10.1007/s10552-013-0292-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 09/13/2013] [Indexed: 12/11/2022]
Abstract
PURPOSE We previously observed that poor DNA repair phenotype is associated with increased breast cancer (BC) risk within families. Here, we examined whether genetic variation in double-strand break repair (DSBR) genes is associated with BC risk and if genotypes are related to phenotype in unaffected women. METHODS Using data from the New York site of the Breast Cancer Family Registry, we investigated 25 single-nucleotide polymorphism (SNPs) involved in DSBR using biospecimens from 337 BC cases and 410 unaffected sister controls. RESULTS Genotypes in XRCC4 were associated with BC risk, with ORs of 1.67 (95 % CI 1.01-2.76) for the combined GA/AA of rs1805377 and 1.69 (95 % CI 1.03-2.77) for rs1056503 TG/GG; these associations were no longer statistically significant in multivariable conditional logistic regression models. When examining the association of SNPs with phenotype, we found that genotypes of XRCC5 rs3834 and rs1051685, which were highly correlated with each other, were associated with end-joining (EJ) capacity; women with the XRCC5 rs3834 GA genotype had better DNA repair as measured by higher levels of EJ capacity (37.8 ± 14.1 % for GA vs. 27.9 ± 11.8 % for GG carriers p = 0.0006). Women with the AA genotype of BRCA1 rs799917 also had higher EJ capacity (35.1 ± 9.2 %) than those with GG (26.4 ± 10.1 %, p = 0.02). CONCLUSIONS Overall, we found that selected DSBR genotypes were associated with phenotype, although they were not associated with BC risk itself, suggesting that phenotypic measures are influenced by endogenous and exogenous factors across the life course and may be better markers than genotypic measures for ascertaining BC risk.
Collapse
Affiliation(s)
- Hui-Chen Wu
- Department of Epidemiology, Mailman School of Public Health of Columbia University, 722 West 168th St., 724A, New York, NY, 10032, USA
| | | | | | | | | | | |
Collapse
|
20
|
Kass EM, Helgadottir HR, Chen CC, Barbera M, Wang R, Westermark UK, Ludwig T, Moynahan ME, Jasin M. Double-strand break repair by homologous recombination in primary mouse somatic cells requires BRCA1 but not the ATM kinase. Proc Natl Acad Sci U S A 2013; 110:5564-9. [PMID: 23509290 PMCID: PMC3619303 DOI: 10.1073/pnas.1216824110] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Homology-directed repair (HDR) is a critical pathway for the repair of DNA double-strand breaks (DSBs) in mammalian cells. Efficient HDR is thought to be crucial for maintenance of genomic integrity during organismal development and tumor suppression. However, most mammalian HDR studies have focused on transformed and immortalized cell lines. We report here the generation of a Direct Repeat (DR)-GFP reporter-based mouse model to study HDR in primary cell types derived from diverse lineages. Embryonic and adult fibroblasts from these mice as well as cells derived from mammary epithelium, ovary, and neonatal brain were observed to undergo HDR at I-SceI endonuclease-induced DSBs at similar frequencies. When the DR-GFP reporter was crossed into mice carrying a hypomorphic mutation in the breast cancer susceptibility gene Brca1, a significant reduction in HDR was detected, showing that BRCA1 is critical for HDR in somatic cell types. Consistent with an HDR defect, Brca1 mutant mice are highly sensitive to the cross-linking agent mitomycin C. By contrast, loss of the DSB signaling ataxia telangiectasia-mutated (ATM) kinase did not significantly alter HDR levels, indicating that ATM is dispensable for HDR. Notably, chemical inhibition of ATM interfered with HDR. The DR-GFP mouse provides a powerful tool for dissecting the genetic requirements of HDR in a diverse array of somatic cell types in a normal, nontransformed cellular milieu.
Collapse
Affiliation(s)
| | - Hildur R. Helgadottir
- Developmental Biology Program
- Weill Graduate School of Medical Sciences of Cornell University, and
| | - Chun-Chin Chen
- Developmental Biology Program
- Weill Graduate School of Medical Sciences of Cornell University, and
| | | | | | | | - Thomas Ludwig
- Department of Molecular and Cellular Biochemistry, Ohio State University Wexner Medical Center, Columbus, OH 43210
| | - Mary Ellen Moynahan
- Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10065; and
| | - Maria Jasin
- Developmental Biology Program
- Weill Graduate School of Medical Sciences of Cornell University, and
| |
Collapse
|
21
|
Kothandapani A, Patrick SM. Evidence for base excision repair processing of DNA interstrand crosslinks. Mutat Res 2012; 743-744:44-52. [PMID: 23219605 DOI: 10.1016/j.mrfmmm.2012.11.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 11/19/2012] [Accepted: 11/24/2012] [Indexed: 12/30/2022]
Abstract
Many bifunctional alkylating agents and anticancer drugs exert their cytotoxicity by producing cross links between the two complementary strands of DNA, termed interstrand crosslinks (ICLs). This blocks the strand separating processes during DNA replication and transcription, which can lead to cell cycle arrest and apoptosis. Cells use multiple DNA repair systems to eliminate the ICLs. Concerted action of repair proteins involved in Nucleotide Excision Repair and Homologous Recombination pathways are suggested to play a key role in the ICL repair. However, recent studies indicate a possible role for Base Excision Repair (BER) in mediating the cytotoxicity of ICL inducing agents in mammalian cells. Elucidating the mechanism of BER mediated modulation of ICL repair would help in understanding the recognition and removal of ICLs and aid in the development of potential therapeutic agents. In this review, the influence of BER proteins on ICL DNA repair and the possible mechanisms of action are discussed.
Collapse
Affiliation(s)
- Anbarasi Kothandapani
- Department of Biochemistry and Cancer Biology, University of Toledo - Health Science Campus, Toledo, OH 43614, USA.
| | - Steve M Patrick
- Department of Biochemistry and Cancer Biology, University of Toledo - Health Science Campus, Toledo, OH 43614, USA.
| |
Collapse
|
22
|
Abstract
Interstrand crosslinks covalently link complementary DNA strands, block replication and transcription, and can trigger cell death. In eukaryotic systems several pathways, including the Fanconi Anemia pathway, are involved in repairing interstrand crosslinks, but their precise mechanisms remain enigmatic. The lack of functional homologs in simpler model organisms has significantly hampered progress in this field. Two recent studies have finally identified a Fanconi-like interstrand crosslink repair pathway in yeast. Future studies in this simplistic model organism promise to greatly improve our basic understanding of complex interstrand crosslink repair pathways like the Fanconi pathway.
Collapse
|
23
|
Daee DL, Ferrari E, Longerich S, Zheng XF, Xue X, Branzei D, Sung P, Myung K. Rad5-dependent DNA repair functions of the Saccharomyces cerevisiae FANCM protein homolog Mph1. J Biol Chem 2012; 287:26563-75. [PMID: 22696213 DOI: 10.1074/jbc.m112.369918] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Interstrand cross-links (ICLs) covalently link complementary DNA strands, block DNA replication, and transcription and must be removed to allow cell survival. Several pathways, including the Fanconi anemia (FA) pathway, can faithfully repair ICLs and maintain genomic integrity; however, the precise mechanisms of most ICL repair processes remain enigmatic. In this study we genetically characterized a conserved yeast ICL repair pathway composed of the yeast homologs (Mph1, Chl1, Mhf1, Mhf2) of four FA proteins (FANCM, FANCJ, MHF1, MHF2). This pathway is epistatic with Rad5-mediated DNA damage bypass and distinct from the ICL repair pathways mediated by Rad18 and Pso2. In addition, consistent with the FANCM role in stabilizing ICL-stalled replication forks, we present evidence that Mph1 prevents ICL-stalled replication forks from collapsing into double-strand breaks. This unique repair function of Mph1 is specific for ICL damage and does not extend to other types of damage. These studies reveal the functional conservation of the FA pathway and validate the yeast model for future studies to further elucidate the mechanism of the FA pathway.
Collapse
Affiliation(s)
- Danielle L Daee
- Genome Instability Section, Genetics, and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | | | | | | | | | | | |
Collapse
|
24
|
The RecQ4 orthologue Hrq1 is critical for DNA interstrand cross-link repair and genome stability in fission yeast. Mol Cell Biol 2011; 32:276-87. [PMID: 22064477 DOI: 10.1128/mcb.06184-11] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Of the five human RecQ family helicases, RecQ4, BLM, and WRN suppress distinct genome instability-linked diseases with severe phenotypes, often with indeterminate etiologies. Here, we functionally define Hrq1, a novel orthologue of RecQ4 from fission yeast. Biochemical analysis of Hrq1 reveals a DEAH box- and ATP-dependent 3'-5' helicase activity on various DNA substrates, including bubbles but not blunt duplexes, characteristic of the RecQ family. Cells lacking Hrq1 suffer spontaneous genomic instability and, consequently, require homologous recombination repair and the DNA damage checkpoint for viability. Hrq1 supports the nucleotide excision repair of DNA damage caused by the chemotherapeutic agent cisplatin and, in certain genetic contexts, UV light. Genetic epistasis analyses reveal that Hrq1 acts parallel to the PCNA/Ubc13/Mms2-dependent postreplication repair (PRR) pathway. Thus, in hrq1Δ cells, lesions are channeled through the PRR pathway, yielding hyper-recombinant and mutator phenotypes; analogous defects may underlie the genetic instability and diseases associated with RecQ4 dysfunction.
Collapse
|
25
|
Goggin M, Sangaraju D, Walker VE, Wickliffe J, Swenberg JA, Tretyakova N. Persistence and repair of bifunctional DNA adducts in tissues of laboratory animals exposed to 1,3-butadiene by inhalation. Chem Res Toxicol 2011; 24:809-17. [PMID: 21452897 DOI: 10.1021/tx200009b] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1,3-Butadiene (BD) is an important industrial and environmental chemical classified as a human carcinogen. The mechanism of BD-mediated cancer is of significant interest because of the widespread exposure of humans to BD from cigarette smoke and urban air. BD is metabolically activated to 1,2,3,4-diepoxybutane (DEB), which is a highly genotoxic and mutagenic bis-alkylating agent believed to be the ultimate carcinogenic species of BD. We have previously identified several types of DEB-specific DNA adducts, including bis-N7-guanine cross-links (bis-N7-BD), N(6)-adenine-N7-guanine cross-links (N(6)A-N7G-BD), and 1,N(6)-dA exocyclic adducts. These lesions were detected in tissues of laboratory rodents exposed to BD by inhalation ( Goggin et al. (2009) Cancer Res. 69 , 2479 -2486 ). In the present work, persistence and repair of bifunctional DEB-DNA adducts in tissues of mice and rats exposed to BD by inhalation were investigated. The half-lives of the most abundant cross-links, bis-N7G-BD, in mouse liver, kidney, and lungs were 2.3-2.4 days, 4.6-5.7 days, and 4.9 days, respectively. The in vitro half-lives of bis-N7G-BD were 3.5 days (S,S isomer) and 4.0 days (meso isomer) due to their spontaneous depurination. In contrast, tissue concentrations of the minor DEB adducts, N7G-N1A-BD and 1,N(6)-HMHP-dA, remained essentially unchanged during the course of the experiment, with an estimated t(1/2) of 36-42 days. No differences were observed between DEB-DNA adduct levels in BD-treated wild type mice and the corresponding animals deficient in methyl purine glycosylase or the Xpa gene. Our results indicate that DEB-induced N7G-N1A-BD and 1,N(6)-HMHP-dA adducts persist in vivo, potentially contributing to mutations and cancer observed as a result of BD exposure.
Collapse
Affiliation(s)
- Melissa Goggin
- Department of Medicinal Chemistry and Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | | | | | | | | | | |
Collapse
|
26
|
Nakanishi K, Cavallo F, Perrouault L, Giovannangeli C, Moynahan ME, Barchi M, Brunet E, Jasin M. Homology-directed Fanconi anemia pathway cross-link repair is dependent on DNA replication. Nat Struct Mol Biol 2011; 18:500-3. [PMID: 21423196 PMCID: PMC3273992 DOI: 10.1038/nsmb.2029] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 01/18/2011] [Indexed: 12/30/2022]
Abstract
Homologous recombination (also termed homology-directed repair, HDR) is a major pathway for the repair of DNA interstrand cross-links (ICLs) in mammalian cells. Cells from individuals with Fanconi anemia (FA) are characterized by extreme ICL sensitivity, but their reported defect in HDR is mild. Here we examined ICL-induced HDR using a GFP reporter and observed a profound defect in ICL-induced HDR in FA cells, but only when the reporter could replicate.
Collapse
Affiliation(s)
- Koji Nakanishi
- Developmental Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
| | | | | | | | | | | | | | | |
Collapse
|
27
|
Neal JA, Meek K. Choosing the right path: does DNA-PK help make the decision? Mutat Res 2011; 711:73-86. [PMID: 21376743 DOI: 10.1016/j.mrfmmm.2011.02.010] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Revised: 02/11/2011] [Accepted: 02/15/2011] [Indexed: 12/30/2022]
Abstract
DNA double-strand breaks are extremely harmful lesions that can lead to genomic instability and cell death if not properly repaired. There are at least three pathways that are responsible for repairing DNA double-strand breaks in mammalian cells: non-homologous end joining, homologous recombination and alternative non-homologous end joining. Here we review each of these three pathways with an emphasis on the role of the DNA-dependent protein kinase, a critical component of the non-homologous end joining pathway, in influencing which pathway is ultimately utilized for repair.
Collapse
Affiliation(s)
- Jessica A Neal
- College of Veterinary Medicine, Department of Microbiology & Molecular Genetics, Michigan State University, East Lansing, Michigan 48824, United States
| | | |
Collapse
|
28
|
Takahashi M, Koi M, Balaguer F, Boland CR, Goel A. MSH3 mediates sensitization of colorectal cancer cells to cisplatin, oxaliplatin, and a poly(ADP-ribose) polymerase inhibitor. J Biol Chem 2011; 286:12157-65. [PMID: 21285347 DOI: 10.1074/jbc.m110.198804] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The MSH3 gene is one of the DNA mismatch repair (MMR) genes that has undergone somatic mutation frequently in MMR-deficient cancers. MSH3, together with MSH2, forms the MutSβ heteroduplex, which interacts with interstrand cross-links (ICLs) induced by drugs such as cisplatin and psoralen. However, the precise role of MSH3 in mediating the cytotoxic effects of ICL-inducing agents remains poorly understood. In this study, we first examined the effects of MSH3 deficiency on cytotoxicity caused by cisplatin and oxaliplatin, another ICL-inducing platinum drug. Using isogenic HCT116-derived clones in which MSH3 expression is controlled by shRNA expression in a Tet-off system, we discovered that MSH3 deficiency sensitized cells to both cisplatin and oxaliplatin at clinically relevant doses. Interestingly, siRNA-induced down-regulation of the MLH1 protein did not affect MSH3-dependent toxicity of these drugs, indicating that this process does not require participation of the canonical MMR pathway. Furthermore, MSH3-deficient cells maintained higher levels of phosphorylated histone H2AX and 53BP1 after oxaliplatin treatment in comparison with MSH3-proficient cells, suggesting that MSH3 plays an important role in repairing DNA double strand breaks (DSBs). This role of MSH3 was further supported by our findings that MSH3-deficient cells were sensitive to olaparib, a poly(ADP-ribose) polymerase inhibitor. Moreover, the combination of oxaliplatin and olaparib exhibited a synergistic effect compared with either treatment individually. Collectively, our results provide novel evidence that MSH3 deficiency contributes to the cytotoxicity of platinum drugs through deficient DSB repair. These data lay the foundation for the development of effective prediction and treatments for cancers with MSH3 deficiency.
Collapse
Affiliation(s)
- Masanobu Takahashi
- Gastrointestinal Cancer Research Laboratory, Division of Gastroenterology, Department of Internal Medicine, Charles A. Sammons Cancer Center and Baylor Research Institute, Baylor University Medical Center, Dallas, Texas 75246-2017, USA
| | | | | | | | | |
Collapse
|
29
|
Tell G, Wilson DM. Targeting DNA repair proteins for cancer treatment. Cell Mol Life Sci 2010; 67:3569-72. [PMID: 20706767 PMCID: PMC2956794 DOI: 10.1007/s00018-010-0484-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Accepted: 07/28/2010] [Indexed: 01/23/2023]
Affiliation(s)
- Gianluca Tell
- Molecular Biology Section, Department of Biomedical Sciences and Technologies, School of Medicine, University of Udine, Piazzale Kolbe 4, 33100, Udine, Italy.
| | | |
Collapse
|
30
|
Guainazzi A, Schärer OD. Using synthetic DNA interstrand crosslinks to elucidate repair pathways and identify new therapeutic targets for cancer chemotherapy. Cell Mol Life Sci 2010; 67:3683-97. [PMID: 20730555 PMCID: PMC3732395 DOI: 10.1007/s00018-010-0492-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Accepted: 07/28/2010] [Indexed: 01/16/2023]
Abstract
Many cancer chemotherapeutic agents form DNA interstrand crosslinks (ICLs), extremely cytotoxic lesions that form covalent bonds between two opposing DNA strands, blocking DNA replication and transcription. However, cellular responses triggered by ICLs can cause resistance in tumor cells, limiting the efficacy of such treatment. Here we discuss recent advances in our understanding of the mechanisms of ICL repair that cause this resistance. The recent development of strategies for the synthesis of site-specific ICLs greatly contributed to these insights. Key features of repair are similar for all ICLs, but there is increasing evidence that the specifics of lesion recognition and synthesis past ICLs by DNA polymerases are dependent upon the structure of ICLs. These new insights provide a basis for the improvement of antitumor therapy by targeting DNA repair pathways that lead to resistance to treatment with crosslinking agents.
Collapse
Affiliation(s)
- Angelo Guainazzi
- Departments of Pharmacological Sciences, Chemistry 619, Stony Brook University, Stony Brook, NY 11794-3400 USA
| | - Orlando D. Schärer
- Departments of Pharmacological Sciences and Chemistry, Chemistry 619, Stony Brook University, Stony Brook, NY 11794-3400 USA
| |
Collapse
|
31
|
Rahn JJ, Lowery MP, Della-Coletta L, Adair GM, Nairn RS. Depletion of Werner helicase results in mitotic hyperrecombination and pleiotropic homologous and nonhomologous recombination phenotypes. Mech Ageing Dev 2010; 131:562-73. [PMID: 20708636 DOI: 10.1016/j.mad.2010.08.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 07/22/2010] [Accepted: 08/03/2010] [Indexed: 11/30/2022]
Abstract
Werner syndrome (WS) is a rare, segmental progeroid syndrome caused by defects in the WRN gene, which encodes a RecQ helicase. WRN has roles in many aspects of DNA metabolism including DNA repair and recombination. In this study, we exploited two different recombination assays previously used to describe a role for the structure-specific endonuclease ERCC1-XPF in mitotic and targeted homologous recombination. We constructed Chinese hamster ovary (CHO) cell lines isogenic with the cell lines used in these previous studies by depleting WRN using shRNA vectors. When intrachromosomal, mitotic recombination was assayed in WRN-depleted CHO cells, a hyperrecombination phenotype was observed, and a small number of aberrant recombinants were generated. Targeted homologous recombination was also examined in WRN-depleted CHO cells using a plasmid-chromosome targeting assay. In these experiments, loss of WRN resulted in a significant decrease in nonhomologous integration events and ablation of recombinants that required random integration of the corrected targeting vector. Aberrant recombinants were also recovered, but only from WRN-depleted cells. The pleiotropic recombination phenotypes conferred by WRN depletion, reflected in distinct homologous and nonhomologous recombination pathways, suggest a role for WRN in processing specific types of homologous recombination intermediates as well as an important function in nonhomologous recombination.
Collapse
Affiliation(s)
- Jennifer J Rahn
- University of Texas M.D. Anderson Cancer Center, Department of Carcinogenesis, Science Park Research Division, P.O. Box 389, Smithville, TX 78597, United States
| | | | | | | | | |
Collapse
|