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Neurauter CG, Pannone M, Sousa MMLD, Wang W, Kuśnierczyk A, Luna L, Sætrom P, Scheffler K, Bjørås M. Enhanced glutathione levels confer resistance to apoptotic and ferroptotic programmed cell death in NEIL DNA glycosylase deficient HAP1 cells. Free Radic Biol Med 2024; 213:470-487. [PMID: 38301978 DOI: 10.1016/j.freeradbiomed.2024.01.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/12/2024] [Accepted: 01/21/2024] [Indexed: 02/03/2024]
Abstract
The NTHL1 and NEIL1-3 DNA glycosylases are major enzymes in the removal of oxidative DNA base lesions, via the base excision repair (BER) pathway. It is expected that lack of these DNA glycosylases activities would render cells vulnerable to oxidative stress, promoting cell death. Intriguingly, we found that single, double, triple, and quadruple DNA glycosylase knockout HAP1 cells are, however, more resistant to oxidative stress caused by genotoxic agents than wild type cells. Furthermore, glutathione depletion in NEIL deficient cells further enhances resistance to cell death induced via apoptosis and ferroptosis. Finally, we observed higher basal level of glutathione and differential expression of NRF2-regulated genes associated with glutathione homeostasis in the NEIL triple KO cells. We propose that lack of NEIL DNA glycosylases causes aberrant transcription and subsequent errors in protein synthesis. This leads to increased endoplasmic reticulum stress and proteotoxic stress. To counteract the elevated intracellular stress, an adaptive response mediated by increased glutathione basal levels, rises in these cells. This study reveals an unforeseen role of NEIL glycosylases in regulation of resistance to oxidative stress, suggesting that modulation of NEIL glycosylase activities is a potential approach to improve the efficacy of e.g. anti-inflammatory therapies.
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Affiliation(s)
- Christine Gran Neurauter
- Department of Microbiology, Oslo University Hospital and University of Oslo, Oslo, 0424, Norway; Centre for Embryology and Healthy Development, University of Oslo, Oslo, 0373, Norway.
| | - Marco Pannone
- Department of Microbiology, Oslo University Hospital and University of Oslo, Oslo, 0424, Norway; Centre for Embryology and Healthy Development, University of Oslo, Oslo, 0373, Norway; Department of Clinical and Molecular Medicine (IKOM), Norwegian University of Science and Technology (NTNU), Trondheim, 7491, Norway.
| | - Mirta Mittelstedt Leal de Sousa
- Department of Microbiology, Oslo University Hospital and University of Oslo, Oslo, 0424, Norway; Centre for Embryology and Healthy Development, University of Oslo, Oslo, 0373, Norway; Department of Clinical and Molecular Medicine (IKOM), Norwegian University of Science and Technology (NTNU), Trondheim, 7491, Norway.
| | - Wei Wang
- Department of Clinical and Molecular Medicine (IKOM), Norwegian University of Science and Technology (NTNU), Trondheim, 7491, Norway.
| | - Anna Kuśnierczyk
- Proteomics and Modomics Experimental Core Facility (PROMEC), Norwegian University of Science and Technology (NTNU), Trondheim, 7491, Norway.
| | - Luisa Luna
- Department of Microbiology, Oslo University Hospital and University of Oslo, Oslo, 0424, Norway; Centre for Embryology and Healthy Development, University of Oslo, Oslo, 0373, Norway.
| | - Pål Sætrom
- Department of Clinical and Molecular Medicine (IKOM), Norwegian University of Science and Technology (NTNU), Trondheim, 7491, Norway.
| | - Katja Scheffler
- Department of Neurology, St.Olavs University Hospital, Trondheim, 7006, Norway; Department of Neuromedicine and Movement Science (INB), Norwegian University of Science and Technology (NTNU), Trondheim, 7491, Norway.
| | - Magnar Bjørås
- Department of Microbiology, Oslo University Hospital and University of Oslo, Oslo, 0424, Norway; Centre for Embryology and Healthy Development, University of Oslo, Oslo, 0373, Norway; Department of Clinical and Molecular Medicine (IKOM), Norwegian University of Science and Technology (NTNU), Trondheim, 7491, Norway.
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2
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Pan YX, Xu QH, Xiao HM, Li CY. Insights into the antibacterial activity and antibacterial mechanism of silver modified fullerene towards Staphylococcus aureus by multiple spectrometric examinations. CHEMOSPHERE 2023; 342:140136. [PMID: 37699456 DOI: 10.1016/j.chemosphere.2023.140136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 09/01/2023] [Accepted: 09/07/2023] [Indexed: 09/14/2023]
Abstract
Clarifying the antibacterial mechanism of silver (Ag)-based materials is of great significance for the rational design, synthesis, and evaluation of antimicrobials. Herein, detailed description of the antibacterial mechanism of a synthesized silver deposited fullerene material (Ag(I)-C60) towards Staphylococcus aureus was surveyed from the point of view of DNA damage by ultraviolet-visible spectroscopy (UV-vis), inductively coupled plasma mass spectrometry (ICP-MS), and liquid chromatography-mass spectrometry (LC-MS). The model material, Ag(I)-C60, was prepared by liquid-liquid interfacial precipitation method, and characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermos-gravimetric analysis (TGA), and nitrogen adsorption/desorption analysis. Ultra-efficient bacteriostatic rate of Ag(I)-C60 was found to be 88.98% under light irradiation for 20 min. UV-vis measurement of the composition changes of four DNA bases showed that they changed in the presence of Ag(I)-C60 under light irradiation, suggesting Ag(I)-C60 could destroy the cells and genetic material of Staphylococcus aureus and thereby inhibit its growth and reproduction. ICP-MS analysis demonstrated the releasing behavior of Ag+ from Ag-based materials. Finally, the transformation pathway of G, A, C, and T were measured by LC-MS, demonstrating the conversion of Adenine (m/z 136.06) to 8-OH-Ade (m/z 174.04). These collective results suggested that Ag(I)-C60 was a new ultra-efficient antibacterial by slowly releasing Ag+ in water and producing a large amount of ROS under light.
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Affiliation(s)
- Yin-Xu Pan
- Key Laboratory of Analytical Chemistry of the State Ethnic Affairs Commission, College of Chemistry and Materials Science, South-Central Minzu University, Wuhan, 430074, China
| | - Qiu-Hui Xu
- Key Laboratory of Oilseeds Processing of Ministry of Agriculture, Hubei Key Laboratory of Lipid Chemistry and Nutrition, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, 430062, China
| | - Hua-Ming Xiao
- Key Laboratory of Analytical Chemistry of the State Ethnic Affairs Commission, College of Chemistry and Materials Science, South-Central Minzu University, Wuhan, 430074, China; Key Laboratory of Oilseeds Processing of Ministry of Agriculture, Hubei Key Laboratory of Lipid Chemistry and Nutrition, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, 430062, China.
| | - Chun-Ya Li
- Key Laboratory of Analytical Chemistry of the State Ethnic Affairs Commission, College of Chemistry and Materials Science, South-Central Minzu University, Wuhan, 430074, China.
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3
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Baljinnyam T, Conrad JW, Sowers ML, Chang-Gu B, Herring JL, Hackfeld LC, Zhang K, Sowers LC. Characterization of a Novel Thermostable DNA Lyase Used To Prepare DNA for Next-Generation Sequencing. Chem Res Toxicol 2023; 36:162-176. [PMID: 36647573 PMCID: PMC9945173 DOI: 10.1021/acs.chemrestox.2c00172] [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] [Indexed: 01/18/2023]
Abstract
Recently, we constructed a hybrid thymine DNA glycosylase (hyTDG) by linking a 29-amino acid sequence from the human thymine DNA glycosylase with the catalytic domain of DNA mismatch glycosylase (MIG) from M. thermoautotrophicum, increasing the overall activity of the glycosylase. Previously, it was shown that a tyrosine to lysine (Y126K) mutation in the catalytic site of MIG could convert the glycosylase activity to a lyase activity. We made the corresponding mutation to our hyTDG to create a hyTDG-lyase (Y163K). Here, we report that the hybrid mutant has robust lyase activity, has activity over a broad temperature range, and is active under multiple buffer conditions. The hyTDG-lyase cleaves an abasic site similar to endonuclease III (Endo III). In the presence of β-mercaptoethanol (β-ME), the abasic site unsaturated aldehyde forms a β-ME adduct. The hyTDG-lyase maintains its preference for cleaving opposite G, as with the hyTDG glycosylase, and the hyTDG-lyase and hyTDG glycosylase can function in tandem to cleave T:G mismatches. The hyTDG-lyase described here should be a valuable tool in studies examining DNA damage and repair. Future studies will utilize these enzymes to quantify T:G mispairs in cells, tissues, and genomic DNA using next-generation sequencing.
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Affiliation(s)
- Tuvshintugs Baljinnyam
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas77555, United States
| | - James W Conrad
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas77555, United States
| | - Mark L Sowers
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas77555, United States.,MD-PhD Combined Degree Program University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas77555, United States
| | - Bruce Chang-Gu
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas77555, United States.,MD-PhD Combined Degree Program University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas77555, United States
| | - Jason L Herring
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas77555, United States
| | - Linda C Hackfeld
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas77555, United States
| | - Kangling Zhang
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas77555, United States
| | - Lawrence C Sowers
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas77555, United States.,Department of Internal Medicine, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas77555, United States
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4
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Polymorphic variant Asp239Tyr of human DNA glycosylase NTHL1 is inactive for removal of a variety of oxidatively-induced DNA base lesions from genomic DNA. DNA Repair (Amst) 2022; 117:103372. [PMID: 35870279 DOI: 10.1016/j.dnarep.2022.103372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 07/08/2022] [Accepted: 07/14/2022] [Indexed: 11/23/2022]
Abstract
Base excision repair is the major pathway for the repair of oxidatively-induced DNA damage, with DNA glycosylases removing modified bases in the first step. Human NTHL1 is specific for excision of several pyrimidine- and purine-derived lesions from DNA, with loss of function NTHL1 showing a predisposition to carcinogenesis. A rare single nucleotide polymorphism of the Nthl1 gene leading to the substitution of Asp239 with Tyr within the active site, occurs within global populations. In this work, we overexpressed and purified the variant NTHL1-Asp239Tyr (NTHL1-D239Y) and determined the substrate specificity of this variant relative to wild-type NTHL1 using gas chromatography-tandem mass spectrometry with isotope-dilution, and oxidatively-damaged genomic DNA containing multiple pyrimidine- and purine-derived lesions. Wild-type NTHL1 excised seven DNA base lesions with different efficiencies, whereas NTHL1-D239Y exhibited no glycosylase activity for any of these lesions. We also measured the activities of human glycosylases OGG1 and NEIL1, and E. coli glycosylases Nth and Fpg under identical experimental conditions. Different substrate specificities among these DNA glycosylases were observed. When mixed with NTHL1-D239Y, the activity of NTHL1 was not reduced, indicating no substrate binding competition. These results and the inactivity of the variant D239Y toward the major oxidatively-induced DNA lesions points to the importance of the understanding of this variant's role in carcinogenesis and the potential of individual susceptibility to cancer in individuals carrying this variant.
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5
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Shah SM, Demidova EV, Lesh RW, Hall MJ, Daly MB, Meyer JE, Edelman MJ, Arora S. Therapeutic implications of germline vulnerabilities in DNA repair for precision oncology. Cancer Treat Rev 2022; 104:102337. [PMID: 35051883 PMCID: PMC9016579 DOI: 10.1016/j.ctrv.2021.102337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 12/30/2021] [Accepted: 12/31/2021] [Indexed: 12/12/2022]
Abstract
DNA repair vulnerabilities are present in a significant proportion of cancers. Specifically, germline alterations in DNA repair not only increase cancer risk but are associated with treatment response and clinical outcomes. The therapeutic landscape of cancer has rapidly evolved with the FDA approval of therapies that specifically target DNA repair vulnerabilities. The clinical success of synthetic lethality between BRCA deficiency and poly(ADP-ribose) polymerase (PARP) inhibition has been truly revolutionary. Defective mismatch repair has been validated as a predictor of response to immune checkpoint blockade associated with durable responses and long-term benefit in many cancer patients. Advances in next generation sequencing technologies and their decreasing cost have supported increased genetic profiling of tumors coupled with germline testing of cancer risk genes in patients. The clinical adoption of panel testing for germline assessment in high-risk individuals has generated a plethora of genetic data, particularly on DNA repair genes. Here, we highlight the therapeutic relevance of germline aberrations in DNA repair to identify patients eligible for precision treatments such as PARP inhibitors (PARPis), immune checkpoint blockade, chemotherapy, radiation therapy and combined treatment. We also discuss emerging mechanisms that regulate DNA repair.
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Affiliation(s)
- Shreya M Shah
- Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, PA, United States; Science Scholars Program, Temple University, Philadelphia, PA, United States
| | - Elena V Demidova
- Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, PA, United States; Kazan Federal University, Kazan, Russian Federation
| | - Randy W Lesh
- Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, PA, United States; Geisinger Commonwealth School of Medicine, Scranton, PA, United States
| | - Michael J Hall
- Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, PA, United States; Department of Clinical Genetics, Fox Chase Cancer Center, Philadelphia, PA, United States
| | - Mary B Daly
- Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, PA, United States; Department of Clinical Genetics, Fox Chase Cancer Center, Philadelphia, PA, United States
| | - Joshua E Meyer
- Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA, United States; Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA, United States
| | - Martin J Edelman
- Department of Hematology/Oncology, Fox Chase Cancer Center, Philadelphia, PA, United States.
| | - Sanjeevani Arora
- Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, PA, United States; Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA, United States.
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6
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Marsden CG, Das L, Nottoli TP, Kathe SD, Doublié S, Wallace SS, Sweasy JB. Mouse Embryonic Fibroblasts Isolated From Nthl1 D227Y Knockin Mice Exhibit Defective DNA Repair and Increased Genome Instability. DNA Repair (Amst) 2022; 109:103247. [PMID: 34826736 PMCID: PMC8787541 DOI: 10.1016/j.dnarep.2021.103247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 11/10/2021] [Accepted: 11/11/2021] [Indexed: 01/03/2023]
Abstract
Oxidative DNA damage as a result of normal cellular metabolism, inflammation, or exposure to exogenous DNA damaging agents if left unrepaired, can result in genomic instability, a precursor to cancer and other diseases. Nth-like DNA glycosylase 1 (NTHL1) is an evolutionarily conserved bifunctional DNA glycosylase that primarily removes oxidized pyrimidine lesions. NTHL1 D239Y is a germline variant identified in both heterozygous and homozygous state in the human population. Here, we have generated a knockin mouse model carrying Nthl1 D227Y (mouse homologue of D239Y) using CRISPR-cas9 genome editing technology and investigated the cellular effects of the variant in the heterozygous (Y/+) and homozygous (Y/Y) state using murine embryonic fibroblasts. We identified a significant increase in double stranded breaks, genomic instability, replication stress and impaired proliferation in both the Nthl1 D227Y heterozygous Y/+ and homozygous mutant Y/Y MEFs. Importantly, we identified that the presence of the D227Y variant interferes with repair by the WT protein, possibly by binding and shielding the lesions. The cellular phenotypes observed in D227Y mutant MEFs suggest that both the heterozygous and homozygous carriers of this NTHL1 germline mutation may be at increased risk for the development of DNA damage-associated diseases, including cancer.
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Affiliation(s)
- Carolyn G. Marsden
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Burlington, VT 05405-0068
| | - Lipsa Das
- Present address: Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, Tucson, AZ 85724-5024, USA
| | - Timothy P. Nottoli
- Section of Comparative Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Scott D. Kathe
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Burlington, VT 05405-0068
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Burlington, VT 05405-0068
| | - Susan S. Wallace
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Burlington, VT 05405-0068
| | - Joann B. Sweasy
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Burlington, VT 05405-0068,Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06510,Present address: Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, Tucson, AZ 85724-5024, USA,Corresponding author contact information: Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, 1515 N Campbell Avenue, Tucson, AZ 85724-5024, USA,
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7
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Complementary Functions of Plant AP Endonucleases and AP Lyases during DNA Repair of Abasic Sites Arising from C:G Base Pairs. Int J Mol Sci 2021; 22:ijms22168763. [PMID: 34445469 PMCID: PMC8395712 DOI: 10.3390/ijms22168763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/10/2021] [Accepted: 08/11/2021] [Indexed: 11/23/2022] Open
Abstract
Abasic (apurinic/apyrimidinic, AP) sites are ubiquitous DNA lesions arising from spontaneous base loss and excision of damaged bases. They may be processed either by AP endonucleases or AP lyases, but the relative roles of these two classes of enzymes are not well understood. We hypothesized that endonucleases and lyases may be differentially influenced by the sequence surrounding the AP site and/or the identity of the orphan base. To test this idea, we analysed the activity of plant and human AP endonucleases and AP lyases on DNA substrates containing an abasic site opposite either G or C in different sequence contexts. AP sites opposite G are common intermediates during the repair of deaminated cytosines, whereas AP sites opposite C frequently arise from oxidized guanines. We found that the major Arabidopsis AP endonuclease (ARP) exhibited a higher efficiency on AP sites opposite G. In contrast, the main plant AP lyase (FPG) showed a greater preference for AP sites opposite C. The major human AP endonuclease (APE1) preferred G as the orphan base, but only in some sequence contexts. We propose that plant AP endonucleases and AP lyases play complementary DNA repair functions on abasic sites arising at C:G pairs, neutralizing the potential mutagenic consequences of C deamination and G oxidation, respectively.
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8
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Hans F, Senarisoy M, Bhaskar Naidu C, Timmins J. Focus on DNA Glycosylases-A Set of Tightly Regulated Enzymes with a High Potential as Anticancer Drug Targets. Int J Mol Sci 2020; 21:ijms21239226. [PMID: 33287345 PMCID: PMC7730500 DOI: 10.3390/ijms21239226] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Accepted: 12/01/2020] [Indexed: 12/25/2022] Open
Abstract
Cancer is the second leading cause of death with tens of millions of people diagnosed with cancer every year around the world. Most radio- and chemotherapies aim to eliminate cancer cells, notably by causing severe damage to the DNA. However, efficient repair of such damage represents a common mechanism of resistance to initially effective cytotoxic agents. Thus, development of new generation anticancer drugs that target DNA repair pathways, and more particularly the base excision repair (BER) pathway that is responsible for removal of damaged bases, is of growing interest. The BER pathway is initiated by a set of enzymes known as DNA glycosylases. Unlike several downstream BER enzymes, DNA glycosylases have so far received little attention and the development of specific inhibitors of these enzymes has been lagging. Yet, dysregulation of DNA glycosylases is also known to play a central role in numerous cancers and at different stages of the disease, and thus inhibiting DNA glycosylases is now considered a valid strategy to eliminate cancer cells. This review provides a detailed overview of the activities of DNA glycosylases in normal and cancer cells, their modes of regulation, and their potential as anticancer drug targets.
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9
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Alhmoud JF, Woolley JF, Al Moustafa AE, Malki MI. DNA Damage/Repair Management in Cancers. Cancers (Basel) 2020; 12:E1050. [PMID: 32340362 PMCID: PMC7226105 DOI: 10.3390/cancers12041050] [Citation(s) in RCA: 166] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 04/18/2020] [Accepted: 04/20/2020] [Indexed: 12/11/2022] Open
Abstract
DNA damage is well recognized as a critical factor in cancer development and progression. DNA lesions create an abnormal nucleotide or nucleotide fragment, causing a break in one or both chains of the DNA strand. When DNA damage occurs, the possibility of generated mutations increases. Genomic instability is one of the most important factors that lead to cancer development. DNA repair pathways perform the essential role of correcting the DNA lesions that occur from DNA damaging agents or carcinogens, thus maintaining genomic stability. Inefficient DNA repair is a critical driving force behind cancer establishment, progression and evolution. A thorough understanding of DNA repair mechanisms in cancer will allow for better therapeutic intervention. In this review we will discuss the relationship between DNA damage/repair mechanisms and cancer, and how we can target these pathways.
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Affiliation(s)
- Jehad F. Alhmoud
- Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, Al-Ahliyya Amman University, Amman 19328, Jordan
| | - John F. Woolley
- Department of Molecular & Clinical Pharmacology, Liverpool University, Liverpool L69 3GE, UK;
| | | | - Mohammed Imad Malki
- College of Medicine, QU Health, Qatar University, Doha P. O. Box 2713, Qatar;
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10
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Kladova OA, Krasnoperov LN, Kuznetsov NA, Fedorova OS. Kinetics and Thermodynamics of DNA Processing by Wild Type DNA-Glycosylase Endo III and Its Catalytically Inactive Mutant Forms. Genes (Basel) 2018; 9:genes9040190. [PMID: 29601551 PMCID: PMC5924532 DOI: 10.3390/genes9040190] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 03/22/2018] [Accepted: 03/27/2018] [Indexed: 02/01/2023] Open
Abstract
Endonuclease III (Endo III or Nth) is one of the key enzymes responsible for initiating the base excision repair of oxidized or reduced pyrimidine bases in DNA. In this study, a thermodynamic analysis of structural rearrangements of the specific and nonspecific DNA-duplexes during their interaction with Endo III is performed based on stopped-flow kinetic data. 1,3-diaza-2-oxophenoxazine (tCO), a fluorescent analog of the natural nucleobase cytosine, is used to record multistep DNA binding and lesion recognition within a temperature range (5-37 °C). Standard Gibbs energy, enthalpy, and entropy of the specific steps are derived from kinetic data using Van't Hoff plots. The data suggest that enthalpy-driven exothermic 5,6-dihydrouracil (DHU) recognition and desolvation-accompanied entropy-driven adjustment of the enzyme-substrate complex into a catalytically active state play equally important parts in the overall process. The roles of catalytically significant amino acids Lys120 and Asp138 in the DNA lesion recognition and catalysis are identified. Lys120 participates not only in the catalytic steps but also in the processes of local duplex distortion, whereas substitution Asp138Ala leads to a complete loss of the ability of Endo III to distort a DNA double chain during enzyme-DNA complex formation.
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Affiliation(s)
- Olga A Kladova
- Institute of Chemical Biology and Fundamental Medicine (ICBFM), 630090 Novosibirsk, Russia.
- Department of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia.
| | - Lev N Krasnoperov
- New Jersey Institute of Technology, Department of Chemistry and Environment Sciences, University Heights, Newark, NJ 07102, USA.
| | - Nikita A Kuznetsov
- Institute of Chemical Biology and Fundamental Medicine (ICBFM), 630090 Novosibirsk, Russia.
| | - Olga S Fedorova
- Institute of Chemical Biology and Fundamental Medicine (ICBFM), 630090 Novosibirsk, Russia.
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11
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D'Errico M, Parlanti E, Pascucci B, Fortini P, Baccarini S, Simonelli V, Dogliotti E. Single nucleotide polymorphisms in DNA glycosylases: From function to disease. Free Radic Biol Med 2017; 107:278-291. [PMID: 27932076 DOI: 10.1016/j.freeradbiomed.2016.12.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 11/25/2016] [Accepted: 12/02/2016] [Indexed: 02/08/2023]
Abstract
Oxidative stress is associated with a growing number of diseases that span from cancer to neurodegeneration. Most oxidatively induced DNA base lesions are repaired by the base excision repair (BER) pathway which involves the action of various DNA glycosylases. There are numerous genome wide studies attempting to associate single-nucleotide polymorphisms (SNPs) with predispositions to various types of disease; often, these common variants do not have significant alterations in their biochemical function and do not exhibit a convincing phenotype. Nevertheless several lines of evidence indicate that SNPs in DNA repair genes may modulate DNA repair capacity and contribute to risk of disease. This overview provides a convincing picture that SNPs of DNA glycosylases that remove oxidatively generated DNA lesions are susceptibility factors for a wide disease spectrum that includes besides cancer (particularly lung, breast and gastrointestinal tract), cochlear/ocular disorders, myocardial infarction and neurodegenerative disorders which can be all grouped under the umbrella of oxidative stress-related pathologies.
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Affiliation(s)
- Mariarosaria D'Errico
- Department of Environment and Primary Prevention, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Eleonora Parlanti
- Department of Environment and Primary Prevention, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Barbara Pascucci
- Department of Environment and Primary Prevention, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy; Istituto di Cristallografia, Consiglio Nazionale delle Ricerche, Via Salaria, Km 29,300, 00016 Monterotondo Stazione, Rome, Italy
| | - Paola Fortini
- Department of Environment and Primary Prevention, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Sara Baccarini
- Department of Environment and Primary Prevention, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Valeria Simonelli
- Department of Environment and Primary Prevention, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Eugenia Dogliotti
- Department of Environment and Primary Prevention, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
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12
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Abstract
Base excision repair (BER) is a key genome maintenance pathway that removes endogenously damaged DNA bases that arise in cells at very high levels on a daily basis. Failure to remove these damaged DNA bases leads to increased levels of mutagenesis and chromosomal instability, which have the potential to drive carcinogenesis. Next-generation sequencing of the germline and tumor genomes of thousands of individuals has uncovered many rare mutations in BER genes. Given that BER is critical for genome maintenance, it is important to determine whether BER genomic variants have functional phenotypes. In this chapter, we present our in silico methods for the identification and prioritization of BER variants for further study. We also provide detailed instructions and commentary on the initial cellular assays we employ to dissect potentially important phenotypes of human BER variants and highlight the strengths and weaknesses of our approaches. BER variants possessing interesting functional phenotypes can then be studied in more detail to provide important mechanistic insights regarding the role of aberrant BER in carcinogenesis.
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13
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Robey-Bond SM, Benson MA, Barrantes-Reynolds R, Bond JP, Wallace SS. Probing the activity of NTHL1 orthologs by targeting conserved amino acid residues. DNA Repair (Amst) 2017; 53:43-51. [PMID: 28292631 PMCID: PMC5421317 DOI: 10.1016/j.dnarep.2017.02.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/01/2017] [Indexed: 01/01/2023]
Abstract
The base excision repair DNA glycosylases, EcoNth and hNTHL1, are homologous, with reported overlapping yet different substrate specificities. The catalytic amino acid residues are known and are identical between the two enzymes although the exact structures of the substrate binding pockets remain to be determined. We sought to explore the sequence basis of substrate differences using a phylogeny-based design of site-directed mutations. Mutations were made for each enzyme in the vicinity of the active site and we examined these variants for glycosylase and lyase activity. Single turnover kinetics were done on a subgroup of these, comparing activity on two lesions, 5,6-dihydrouracil and 5,6-dihydrothymine, with different opposite bases. We report that wild type hNTHL1 and EcoNth are remarkably alike with respect to the specificity of the glycosylase reaction, and although hNTHL1 is a much slower enzyme than EcoNth, the tighter binding of hNTHL1 compensates, resulting in similar kcat/Kd values for both enzymes with each of the substrates tested. For the hNTHL1 variant Gln287Ala, the specificity for substrates positioned opposite G is lost, but not that of substrates positioned opposite A, suggesting a discrimination role for this residue. The EcoNth Thr121 residue influences enzyme binding to DNA, as binding is significantly reduced with the Thr121Ala variant. Finally, we present evidence that hNTHL1 Asp144, unlike the analogous EcoNth residue Asp44, may be involved in resolving the glycosylase transition state.
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Affiliation(s)
- Susan M Robey-Bond
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Stafford Hall, 95 Carrigan Drive, Burlington, VT 05405-0068, United States
| | - Meredith A Benson
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Stafford Hall, 95 Carrigan Drive, Burlington, VT 05405-0068, United States
| | - Ramiro Barrantes-Reynolds
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Stafford Hall, 95 Carrigan Drive, Burlington, VT 05405-0068, United States
| | - Jeffrey P Bond
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Stafford Hall, 95 Carrigan Drive, Burlington, VT 05405-0068, United States
| | - Susan S Wallace
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Stafford Hall, 95 Carrigan Drive, Burlington, VT 05405-0068, United States.
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14
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Massaad MJ, Zhou J, Tsuchimoto D, Chou J, Jabara H, Janssen E, Glauzy S, Olson BG, Morbach H, Ohsumi TK, Schmitz K, Kyriacos M, Kane J, Torisu K, Nakabeppu Y, Notarangelo LD, Chouery E, Megarbane A, Kang PB, Al-Idrissi E, Aldhekri H, Meffre E, Mizui M, Tsokos GC, Manis JP, Al-Herz W, Wallace SS, Geha RS. Deficiency of base excision repair enzyme NEIL3 drives increased predisposition to autoimmunity. J Clin Invest 2016; 126:4219-4236. [PMID: 27760045 DOI: 10.1172/jci85647] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 09/06/2016] [Indexed: 12/17/2022] Open
Abstract
Alterations in the apoptosis of immune cells have been associated with autoimmunity. Here, we have identified a homozygous missense mutation in the gene encoding the base excision repair enzyme Nei endonuclease VIII-like 3 (NEIL3) that abolished enzymatic activity in 3 siblings from a consanguineous family. The NEIL3 mutation was associated with fatal recurrent infections, severe autoimmunity, hypogammaglobulinemia, and impaired B cell function in these individuals. The same homozygous NEIL3 mutation was also identified in an asymptomatic individual who exhibited elevated levels of serum autoantibodies and defective peripheral B cell tolerance, but normal B cell function. Further analysis of the patients revealed an absence of LPS-responsive beige-like anchor (LRBA) protein expression, a known cause of immunodeficiency. We next examined the contribution of NEIL3 to the maintenance of self-tolerance in Neil3-/- mice. Although Neil3-/- mice displayed normal B cell function, they exhibited elevated serum levels of autoantibodies and developed nephritis following treatment with poly(I:C) to mimic microbial stimulation. In Neil3-/- mice, splenic T and B cells as well as germinal center B cells from Peyer's patches showed marked increases in apoptosis and cell death, indicating the potential release of self-antigens that favor autoimmunity. These findings demonstrate that deficiency in NEIL3 is associated with increased lymphocyte apoptosis, autoantibodies, and predisposition to autoimmunity.
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15
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Schuermann D, Scheidegger SP, Weber AR, Bjørås M, Leumann CJ, Schär P. 3CAPS - a structural AP-site analogue as a tool to investigate DNA base excision repair. Nucleic Acids Res 2016; 44:2187-98. [PMID: 26733580 PMCID: PMC4797279 DOI: 10.1093/nar/gkv1520] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 12/18/2015] [Indexed: 12/04/2022] Open
Abstract
Abasic sites (AP-sites) are frequent DNA lesions, arising by spontaneous base hydrolysis or as intermediates of base excision repair (BER). The hemiacetal at the anomeric centre renders them chemically reactive, which presents a challenge to biochemical and structural investigation. Chemically more stable AP-site analogues have been used to avoid spontaneous decay, but these do not fully recapitulate the features of natural AP–sites. With its 3′–phosphate replaced by methylene, the abasic site analogue 3CAPS was suggested to circumvent some of these limitations. Here, we evaluated the properties of 3CAPS in biochemical BER assays with mammalian proteins. 3CAPS-containing DNA substrates were processed by APE1, albeit with comparably poor efficiency. APE1-cleaved 3CAPS can be extended by DNA polymerase β but repaired only by strand displacement as the 5′–deoxyribophosphate (dRP) cannot be removed. DNA glycosylases physically and functionally interact with 3CAPS substrates, underlining its structural integrity and biochemical reactivity. The AP lyase activity of bifunctional DNA glycosylases (NTH1, NEIL1, FPG), however, was fully inhibited. Notably, 3CAPS-containing DNA also effectively inhibited the activity of bifunctional glycosylases on authentic substrates. Hence, the chemically stable 3CAPS with its preserved hemiacetal functionality is a potent tool for BER research and a potential inhibitor of bifunctional DNA glycosylases.
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Affiliation(s)
- David Schuermann
- Department of Biomedicine, University of Basel, Mattenstrasse 28, CH-4058 Basel, Switzerland
| | - Simon P Scheidegger
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Alain R Weber
- Department of Biomedicine, University of Basel, Mattenstrasse 28, CH-4058 Basel, Switzerland
| | - Magnar Bjørås
- Department of Microbiology, Oslo University Hospital and University of Oslo, Rikshospitalet, PO Box 4950 Nydalen, N-0424 Oslo, Norway Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, PO Box 8905, N-7491 Trondheim, Norway
| | - Christian J Leumann
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Primo Schär
- Department of Biomedicine, University of Basel, Mattenstrasse 28, CH-4058 Basel, Switzerland
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16
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Bauer NC, Corbett AH, Doetsch PW. The current state of eukaryotic DNA base damage and repair. Nucleic Acids Res 2015; 43:10083-101. [PMID: 26519467 PMCID: PMC4666366 DOI: 10.1093/nar/gkv1136] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 10/16/2015] [Indexed: 12/15/2022] Open
Abstract
DNA damage is a natural hazard of life. The most common DNA lesions are base, sugar, and single-strand break damage resulting from oxidation, alkylation, deamination, and spontaneous hydrolysis. If left unrepaired, such lesions can become fixed in the genome as permanent mutations. Thus, evolution has led to the creation of several highly conserved, partially redundant pathways to repair or mitigate the effects of DNA base damage. The biochemical mechanisms of these pathways have been well characterized and the impact of this work was recently highlighted by the selection of Tomas Lindahl, Aziz Sancar and Paul Modrich as the recipients of the 2015 Nobel Prize in Chemistry for their seminal work in defining DNA repair pathways. However, how these repair pathways are regulated and interconnected is still being elucidated. This review focuses on the classical base excision repair and strand incision pathways in eukaryotes, considering both Saccharomyces cerevisiae and humans, and extends to some important questions and challenges facing the field of DNA base damage repair.
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Affiliation(s)
- Nicholas C Bauer
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA Graduate Program in Biochemistry, Cell, and Developmental Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Anita H Corbett
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Paul W Doetsch
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 30322, USA Department of Radiation Oncology, Emory University School of Medicine, Atlanta, GA 30322, USA Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA 30322, USA
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17
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Sharbeen G, McCarroll J, Goldstein D, Phillips PA. Exploiting base excision repair to improve therapeutic approaches for pancreatic cancer. Front Nutr 2015; 2:10. [PMID: 25988138 PMCID: PMC4428371 DOI: 10.3389/fnut.2015.00010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 03/10/2015] [Indexed: 12/13/2022] Open
Abstract
Pancreatic ductal adenocarcinoma (PDA) is a highly chemoresistant and metastatic disease with a dismal 5-year survival rate of 6%. More effective therapeutic targets and approaches are urgently needed to tackle this devastating disease. The base excision repair (BER) pathway has been identified as a predictor of therapeutic response, prognostic factor, and therapeutic target in a variety of cancers. This review will discuss our current understanding of BER in PDA and its potential to improve PDA treatment.
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Affiliation(s)
- George Sharbeen
- Pancreatic Cancer Translational Research Group, Lowy Cancer Research Centre, Prince of Wales Clinical School, UNSW Australia , Sydney, NSW , Australia
| | - Joshua McCarroll
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia , Sydney, NSW , Australia
| | - David Goldstein
- Pancreatic Cancer Translational Research Group, Lowy Cancer Research Centre, Prince of Wales Clinical School, UNSW Australia , Sydney, NSW , Australia
| | - Phoebe A Phillips
- Pancreatic Cancer Translational Research Group, Lowy Cancer Research Centre, Prince of Wales Clinical School, UNSW Australia , Sydney, NSW , Australia
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18
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Kidane D, Chae WJ, Czochor J, Eckert KA, Glazer PM, Bothwell ALM, Sweasy JB. Interplay between DNA repair and inflammation, and the link to cancer. Crit Rev Biochem Mol Biol 2014; 49:116-39. [PMID: 24410153 DOI: 10.3109/10409238.2013.875514] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
DNA damage and repair are linked to cancer. DNA damage that is induced endogenously or from exogenous sources has the potential to result in mutations and genomic instability if not properly repaired, eventually leading to cancer. Inflammation is also linked to cancer. Reactive oxygen and nitrogen species (RONs) produced by inflammatory cells at sites of infection can induce DNA damage. RONs can also amplify inflammatory responses, leading to increased DNA damage. Here, we focus on the links between DNA damage, repair, and inflammation, as they relate to cancer. We examine the interplay between chronic inflammation, DNA damage and repair and review recent findings in this rapidly emerging field, including the links between DNA damage and the innate immune system, and the roles of inflammation in altering the microbiome, which subsequently leads to the induction of DNA damage in the colon. Mouse models of defective DNA repair and inflammatory control are extensively reviewed, including treatment of mouse models with pathogens, which leads to DNA damage. The roles of microRNAs in regulating inflammation and DNA repair are discussed. Importantly, DNA repair and inflammation are linked in many important ways, and in some cases balance each other to maintain homeostasis. The failure to repair DNA damage or to control inflammatory responses has the potential to lead to cancer.
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Affiliation(s)
- Dawit Kidane
- Departments of Therapeutic Radiology and Genetics
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19
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Germ-line variant of human NTH1 DNA glycosylase induces genomic instability and cellular transformation. Proc Natl Acad Sci U S A 2013; 110:14314-9. [PMID: 23940330 DOI: 10.1073/pnas.1306752110] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Base excision repair (BER) removes at least 20,000 DNA lesions per human cell per day and is critical for the maintenance of genomic stability. We hypothesize that aberrant BER, resulting from mutations in BER genes, can lead to genomic instability and cancer. The first step in BER is catalyzed by DNA N-glycosylases. One of these, n(th) endonuclease III-like (NTH1), removes oxidized pyrimidines from DNA, including thymine glycol. The rs3087468 single nucleotide polymorphism of the NTH1 gene is a G-to-T base substitution that results in the NTH1 D239Y variant protein that occurs in ∼6.2% of the global population and is found in Europeans, Asians, and sub-Saharan Africans. In this study, we functionally characterize the effect of the D239Y variant expressed in immortal but nontransformed human and mouse mammary epithelial cells. We demonstrate that expression of the D239Y variant in cells also expressing wild-type NTH1 leads to genomic instability and cellular transformation as assessed by anchorage-independent growth, focus formation, invasion, and chromosomal aberrations. We also show that cells expressing the D239Y variant are sensitive to ionizing radiation and hydrogen peroxide and accumulate double strand breaks after treatment with these agents. The DNA damage response is also activated in D239Y-expressing cells. In combination, our data suggest that individuals possessing the D239Y variant are at risk for genomic instability and cancer.
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20
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Liu M, Doublié S, Wallace SS. Neil3, the final frontier for the DNA glycosylases that recognize oxidative damage. Mutat Res 2012; 743-744:4-11. [PMID: 23274422 DOI: 10.1016/j.mrfmmm.2012.12.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 12/18/2012] [Indexed: 11/17/2022]
Abstract
DNA glycosylases are the enzymes that initiate the Base Excision Repair (BER) process that protects all organisms from the mutagenic and/or cytotoxic effects of DNA base lesions. Endonuclease VIII like proteins (Neil1, Neil2 and Neil3) are found in vertebrate genomes and are homologous to the well-characterized bacterial DNA glycosylases, Formamidopyrimidine DNA glycosylase (Fpg) and Endonuclease VIII (Nei). Since the initial discovery of the Neil proteins, much progress has been made on characterizing Neil1 and Neil2. It was not until recently, however, that Neil3 was shown to be a functional DNA glycosylase having a different substrate specificity and unusual structural features compared with other Fpg/Nei homologs. Although the biological functions of Neil3 still remain an enigma, this review highlights recent biochemical and structural data that may ultimately shed light on its biological role.
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Affiliation(s)
- Minmin Liu
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Stafford Hall, 95 Carrigan Dr., Burlington, VT 05405-0086, United States.
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Stafford Hall, 95 Carrigan Dr., Burlington, VT 05405-0086, United States
| | - Susan S Wallace
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Stafford Hall, 95 Carrigan Dr., Burlington, VT 05405-0086, United States.
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21
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Bosshard M, Markkanen E, van Loon B. Base excision repair in physiology and pathology of the central nervous system. Int J Mol Sci 2012. [PMID: 23203191 PMCID: PMC3546685 DOI: 10.3390/ijms131216172] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Relatively low levels of antioxidant enzymes and high oxygen metabolism result in formation of numerous oxidized DNA lesions in the tissues of the central nervous system. Accumulation of damage in the DNA, due to continuous genotoxic stress, has been linked to both aging and the development of various neurodegenerative disorders. Different DNA repair pathways have evolved to successfully act on damaged DNA and prevent genomic instability. The predominant and essential DNA repair pathway for the removal of small DNA base lesions is base excision repair (BER). In this review we will discuss the current knowledge on the involvement of BER proteins in the maintenance of genetic stability in different brain regions and how changes in the levels of these proteins contribute to aging and the onset of neurodegenerative disorders.
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Affiliation(s)
- Matthias Bosshard
- Institute for Veterinary Biochemistry and Molecular Biology, University of Zürich-Irchel, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
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22
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Characterization of magnesium requirement of human 5'-tyrosyl DNA phosphodiesterase mediated reaction. BMC Res Notes 2012; 5:134. [PMID: 22405347 PMCID: PMC3315744 DOI: 10.1186/1756-0500-5-134] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 03/09/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Topo-poisons can produce an enzyme-DNA complex linked by a 3'- or 5'-phosphotyrosyl covalent bond. 3'-phosphotyrosyl bonds can be repaired by tyrosyl DNA phosphodiesterase-1 (TDP1), an enzyme known for years, but a complementary human enzyme 5'-tyrosyl DNA phosphodiesterase (hTDP2) that cleaves 5'-phosphotyrosyl bonds has been reported only recently. Although hTDP2 possesses both 3'- and 5'- tyrosyl DNA phosphodiesterase activity, the role of Mg2+ in its activity was not studied in sufficient details. RESULTS In this study we showed that purified hTDP2 does not exhibit any 5'-phosphotyrosyl phosphodiesterase activity in the absence of Mg2+/Mn2+, and that neither Zn2+ or nor Ca2+ can activate hTDP2. Mg2+ also controls 3'-phosphotyrosyl activity of TDP2. In MCF-7 cell extracts and de-yolked zebrafish embryo extracts, Mg2+ controlled 5'-phosphotyrosyl activity. This study also showed that there is an optimal Mg2+ concentration above which it is inhibitory for hTDP2 activity. CONCLUSION These results altogether reveal the optimal Mg2+ requirement in hTDP2 mediated reaction.
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23
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Ganguly M, Szulik MW, Donahue PS, Clancy K, Stone MP, Gold B. Thermodynamic signature of DNA damage: characterization of DNA with a 5-hydroxy-2'-deoxycytidine·2'-deoxyguanosine base pair. Biochemistry 2012; 51:2018-27. [PMID: 22332945 DOI: 10.1021/bi3000269] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Oxidation of DNA due to exposure to reactive oxygen species is a major source of DNA damage. One of the oxidation lesions formed, 5-hydroxy-2'-deoxycytidine, has been shown to miscode by some replicative DNA polymerases but not by error prone polymerases capable of translesion synthesis. The 5-hydroxy-2'-deoxycytidine lesion is repaired by DNA glycosylases that require the 5-hydroxycytidine base to be extrahelical so it can enter into the enzyme's active site where it is excised off the DNA backbone to afford an abasic site. The thermodynamic and nuclear magnetic resonance results presented here describe the effect of a 5-hydroxy-2'-deoxycytidine·2'-deoxyguanosine base pair on the stability of two different DNA duplexes. The results demonstrate that the lesion is highly destabilizing and that the energy barrier for the unstacking of 5-hydroxy-2'-deoxycytidine from the DNA duplex may be low. This could provide a thermodynamic mode of adduct identification by DNA glycosylases that requires the lesion to be extrahelical.
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Affiliation(s)
- Manjori Ganguly
- Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
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24
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Wallace SS, Murphy DL, Sweasy JB. Base excision repair and cancer. Cancer Lett 2012; 327:73-89. [PMID: 22252118 DOI: 10.1016/j.canlet.2011.12.038] [Citation(s) in RCA: 224] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 12/20/2011] [Accepted: 12/24/2011] [Indexed: 01/13/2023]
Abstract
Base excision repair is the system used from bacteria to man to remove the tens of thousands of endogenous DNA damages produced daily in each human cell. Base excision repair is required for normal mammalian development and defects have been associated with neurological disorders and cancer. In this paper we provide an overview of short patch base excision repair in humans and summarize current knowledge of defects in base excision repair in mouse models and functional studies on short patch base excision repair germ line polymorphisms and their relationship to cancer. The biallelic germ line mutations that result in MUTYH-associated colon cancer are also discussed.
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Affiliation(s)
- Susan S Wallace
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Burlington, 05405-0068, United States.
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25
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DNA glycosylases: in DNA repair and beyond. Chromosoma 2011; 121:1-20. [PMID: 22048164 PMCID: PMC3260424 DOI: 10.1007/s00412-011-0347-4] [Citation(s) in RCA: 257] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Revised: 10/10/2011] [Accepted: 10/11/2011] [Indexed: 12/20/2022]
Abstract
The base excision repair machinery protects DNA in cells from the damaging effects of oxidation, alkylation, and deamination; it is specialized to fix single-base damage in the form of small chemical modifications. Base modifications can be mutagenic and/or cytotoxic, depending on how they interfere with the template function of the DNA during replication and transcription. DNA glycosylases play a key role in the elimination of such DNA lesions; they recognize and excise damaged bases, thereby initiating a repair process that restores the regular DNA structure with high accuracy. All glycosylases share a common mode of action for damage recognition; they flip bases out of the DNA helix into a selective active site pocket, the architecture of which permits a sensitive detection of even minor base irregularities. Within the past few years, it has become clear that nature has exploited this ability to read the chemical structure of DNA bases for purposes other than canonical DNA repair. DNA glycosylases have been brought into context with molecular processes relating to innate and adaptive immunity as well as to the control of DNA methylation and epigenetic stability. Here, we summarize the key structural and mechanistic features of DNA glycosylases with a special focus on the mammalian enzymes, and then review the evidence for the newly emerging biological functions beyond the protection of genome integrity.
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26
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Nemec AA, Wallace SS, Sweasy JB. Variant base excision repair proteins: contributors to genomic instability. Semin Cancer Biol 2010; 20:320-8. [PMID: 20955798 DOI: 10.1016/j.semcancer.2010.10.010] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cells sustain endogenous DNA damage at rates greater than 20,000 DNA lesions per cell per day. These damages occur largely as a result of the inherently unstable nature of DNA and the presence of reactive oxygen species within cells. The base excision repair system removes the majority of DNA lesions resulting from endogenous DNA damage. There are several enzymes that function during base excision repair. Importantly, there are over 100 germline single nucleotide polymorphisms in genes that function in base excision repair and that result in non-synonymous amino acid substitutions in the proteins they encode. Somatic variants of these enzymes are also found in human tumors. Variant repair enzymes catalyze aberrant base excision repair. Aberrant base excision repair combined with continuous endogenous DNA damage over time has the potential to lead to a mutator phenotype. Mutations that arise in key growth control genes, imbalances in chromosome number, chromosomal translocations, and loss of heterozygosity can result in the initiation of human cancer or its progression.
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Affiliation(s)
- Antonia A Nemec
- Department of Therapeutic Radiology, 15 York Street, New Haven, CT 06510, United States
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27
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Sejersted Y, Aasland AL, Bjørås M, Eide L, Saugstad OD. Accumulation of 8-oxoguanine in liver DNA during hyperoxic resuscitation of newborn mice. Pediatr Res 2009; 66:533-8. [PMID: 19668103 DOI: 10.1203/pdr.0b013e3181ba1a42] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Supplementary oxygen during resuscitation of the asphyxiated newborn is associated with long-term detrimental effects including increased risk of childhood cancer. It is suspected that the resuscitation procedure results in accumulated DNA damage and mutagenesis. Base excision repair (BER) is the major pathway for repair of premutagenic oxidative DNA lesions. This study addresses DNA base damage and BER in brain, lung, and liver in neonatal mice (P7) after hyperoxic resuscitation. Mice were randomized to 8% oxygen or room air for 60 min in a closed chamber and subsequent reoxygenation with 100% oxygen for 0 to 90 min. During this treatment, 8-oxoguanine accumulated in liver but not in lung or cerebellum. We observed a linear relation between 8-oxoguanine and reoxygenation time in liver DNA from hypoxic animals (n = 28; B = 0.011 [0.001, 0.020]; p = 0.037). BER activity was not significantly changed during resuscitation. Our data suggest that after hypoxia, the capacity for immediate repair in liver tissue is inadequate to meet increasing amounts of DNA damage. The duration of supplementary oxygen use during resuscitation should be kept as short as justifiable to minimize the risk of genetic instability.
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Affiliation(s)
- Yngve Sejersted
- Department of Pediatric Research, University of Oslo, Oslo University Hospital Rikshospitalet, Oslo, Norway.
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28
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Hildrestrand GA, Duggal S, Bjørås M, Luna L, Brinchmann JE. Modulation of DNA glycosylase activities in mesenchymal stem cells. Exp Cell Res 2009; 315:2558-67. [PMID: 19477173 DOI: 10.1016/j.yexcr.2009.05.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Revised: 04/28/2009] [Accepted: 05/19/2009] [Indexed: 11/19/2022]
Abstract
Adipose-tissue derived mesenchymal stem cells (AT-MSCs) are a promising tool for use in cell-based therapies. However, in vitro expansion is required to obtain clinically relevant cell numbers, and this might increase the chance of genomic instability. DNA repair is crucial for maintaining DNA integrity. Here we have compared the initial step of base excision repair in uncultured and cultured AT-MSCs by analysis of base removal activities and expression levels of relevant DNA glycosylases. Uracil, 5-hydroxyuracil and ethenoadenine removal activities were upregulated in cultured cells compared to uncultured cells. In contrast, both the 8-oxo-7,8-dihydroguanine (8-oxoG) removal activity and the concentration of 8-oxoG bases in the DNA were reduced in the cultured cells. Gene expression analysis showed no substantial changes in mRNA expression. The glycosylase activities remained stable through at least 12 passages, suggesting that DNA repair is proficient through the period required for in vitro expansion of AT-MSCs to clinically relevant numbers.
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Affiliation(s)
- Gunn A Hildrestrand
- Centre for Molecular Biology and Neuroscience and Institute of Medical Microbiology, Rikshospitalet University Hospital, Oslo, Norway
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Yndestad A, Neurauter CG, Oie E, Forstrøm RJ, Vinge LE, Eide L, Luna L, Aukrust P, Bjørås M. Up-regulation of myocardial DNA base excision repair activities in experimental heart failure. Mutat Res 2009; 666:32-8. [PMID: 19481677 DOI: 10.1016/j.mrfmmm.2009.03.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Revised: 03/11/2009] [Accepted: 03/19/2009] [Indexed: 01/20/2023]
Abstract
Base excision repair (BER) is the major pathway to counteract the genotoxic effect of endogenous DNA damaging agents. The present study investigated the enzymatic activities and gene transcription of DNA glycosylases initiating BER in an experimental heart failure (HF) model. Rats were subjected to myocardial infarction or sham-operated. Twenty-eight days after surgical intervention cell-free protein extracts, total RNA and genomic DNA were isolated to analyze DNA glycosylase and AP-endonuclease activities, transcript levels of DNA glycosylases and accumulation of oxidative DNA damage. The capacity to remove major oxidation products (e.g., formamidopyrimidine and 5-hydroxycytosine) was significantly increased in the border zone of infarcted area, while the capacity to remove the highly mutagenic 8-oxoguanine residue was enhanced both in non-infarcted and infarcted areas of left ventricle (LV). DNA glycosylase activities towards 3-methyladenine and uracil were up-regulated in infarcted and non-infarcted areas of LV, indicating that generation of alkylated and deaminated base lesions on DNA increase during HF. Finally, we found no difference in accumulation of oxidative DNA damage in myocardial tissue between rats with post-myocardial infarction and sham-operated rats. This up-regulation of activities, initiating the BER pathway, could play an important role during HF by counteracting the effect of genotoxic stress, structural damage of tissue and myocardial remodeling.
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Affiliation(s)
- Arne Yndestad
- Section of Clinical Immunology and Infectious Diseases, Oslo University Hospital, University of Oslo, N-0027 Oslo, Norway
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Rolseth V, Rundén-Pran E, Luna L, McMurray C, Bjørås M, Ottersen OP. Widespread distribution of DNA glycosylases removing oxidative DNA lesions in human and rodent brains. DNA Repair (Amst) 2008; 7:1578-88. [PMID: 18603019 DOI: 10.1016/j.dnarep.2008.06.007] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Revised: 06/05/2008] [Accepted: 06/06/2008] [Indexed: 12/22/2022]
Abstract
High metabolic activity and low levels of antioxidant enzymes make neurons particularly prone to damage by reactive oxygen species. Thus, repair of oxidative DNA damage is essential for normal brain function. Base excision repair is the major pathway for repair of oxidative DNA damage, and is initiated by DNA glycosylases recognizing and removing the damaged base. In mammalian cells at least five different DNA glycosylases with overlapping substrate specificity, NEIL1, NEIL2, NEIL3, OGG1 and NTH1, remove oxidative DNA base lesions. Here we report mRNA expression and distribution of these five DNA glycosylases in human and rodent brains using in situ hybridization and Northern blotting supported by glycosylase activity assays. NEIL1, NEIL2, OGG1 and NTH1 showed widespread expression at all ages. In situ hybridization studies in mouse brain showed that expression of mNeil1 increased with age. In newborn mouse brain, mNeil3 revealed a discrete expression pattern in brain regions known to harbour stem cell populations, i.e., the subventricular zone, the rostral migratory stream, and the hilar region of the hippocampal formation. Expression of mNeil3 decreased with age, and in old mice brains could be detected only in layer V of neocortex. MNth1 was constitutively expressed during lifespan. In Northern blots, mOgg1 expression showed a transient decrease followed by an increase after 8 weeks of age. Assays for faPy DNA glycosylase activity revealed increased activity level with age in all brain regions analyzed. The widespread but differential expression of the DNA glycosylases recognizing oxidative base lesions suggests distinct and age dependent roles of these enzymes in genome maintenance in brain. The distribution of mNeil3 is particularly intriguing and points to a specific role of this enzyme in stem cell differentiation.
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Affiliation(s)
- Veslemøy Rolseth
- Centre for Molecular Biology and Neuroscience, Institute of Medical Microbiology, University of Oslo, Rikshospitalet HF, Oslo, Norway
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31
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Sidorenko VS, Mechetin GV, Nevinsky GA, Zharkov DO. Ionic strength and magnesium affect the specificity of Escherichia coli and human 8-oxoguanine-DNA glycosylases. FEBS J 2008; 275:3747-60. [PMID: 18557781 DOI: 10.1111/j.1742-4658.2008.06521.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An abundant oxidative lesion, 8-oxo-7,8-dihydroguanine (8-oxoG), often directs the misincorporation of dAMP during replication. To prevent mutations, cells possess an enzymatic system for the removal of 8-oxoG. A key element of this system is 8-oxoguanine-DNA glycosylase (Fpg in bacteria, OGG1 in eukaryotes), which must excise 8-oxoG from 8-oxoG:C pairs but not from 8-oxoG:A. We investigated the influence of various factors, including ionic strength, the presence of Mg(2+) and organic anions, polyamides, crowding agents and two small heterocyclic compounds (biotin and caffeine) on the activity and opposite-base specificity of Escherichia coli Fpg and human OGG1. The activity of both enzymes towards 8-oxoG:A decreased sharply with increasing salt and Mg(2+) concentration, whereas the activity on 8-oxoG:C was much more stable, resulting in higher opposite-base specificity when salt and Mg(2+) were at near-physiological concentrations. This tendency was observed with both Cl(-) and glutamate as the major anions in the reaction mixture. Kinetic and binding parameters for the processing of 8-oxoG:C and 8-oxoG:A by Fpg and OGG1 were determined under several different conditions. Polyamines, crowding agents, biotin and caffeine affected the activity and specificity of Fpg or OGG1 only marginally. We conclude that, in the intracellular environment, the specificity of Fpg and OGG1 for 8-oxoG:C versus 8-oxoG:A is mostly due to high ionic strength and Mg(2+).
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32
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Rolseth V, Rundén-Pran E, Neurauter CG, Yndestad A, Luna L, Aukrust P, Ottersen OP, Bjørås M. Base excision repair activities in organotypic hippocampal slice cultures exposed to oxygen and glucose deprivation. DNA Repair (Amst) 2008; 7:869-78. [PMID: 18406215 DOI: 10.1016/j.dnarep.2008.02.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Revised: 02/07/2008] [Accepted: 02/12/2008] [Indexed: 01/22/2023]
Abstract
The capacity for DNA repair is likely to be one of the factors that determine the vulnerability of neurons to ischemic stress and may influence the pathological outcome of stroke. In this report, initiation of base excision repair (BER) was assessed by analysis of enzyme activity and gene expression level of DNA glycosylases and AP-endonucleases in rat organotypic hippocampal slice cultures exposed to oxygen and glucose deprivation (OGD) - an in vitro model of stroke. Under basal conditions, AP-endonuclease activity and base removal of ethenoadenine and 8-oxoguanine (8-oxoG) were higher (by approximately 20-35 %) in CA3/fascia dentata (FD) than in CA1. Base removal of uracil did not differ between the two hippocampal regions, while removal of 5-hydroxyuracil (5-OHU) was slightly less efficient in CA3/FD than in CA1. Analyses performed immediately after 30 min of OGD revealed a decreased AP-endonuclease activity (by approximately 20%) in CA1 as well as CA3/FD, and an increased ethenoadenine activity (by approximately 25%) in CA1. Activities for 8-oxoG, 5-OHU and uracil showed no significant changes at this time point. At 8h after OGD, none of the enzyme activities differed from control values. Real-time RT-PCR showed that transcription of DNA glycosylases, including Ogg1, Nth1, Ung, Aag, Neil1 and Neil2 were not changed in response to OGD treatment (t=0 h). The hippocampal expression of Neil2 was low compared with the other DNA glycosylases. These data indicate that CA1 has a lower capacity than CA3/FD for removal of base lesions under basal conditions. The relatively low capacity for BER in basal conditions and the apparent failure to upregulate repair of oxidative damage after OGD might contribute to the high vulnerability of CA1 to ischemic injury.
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Affiliation(s)
- Veslemøy Rolseth
- Centre for Molecular Biology and Neuroscience, Institute of Medical Microbiology, University of Oslo, Rikshospitalet, N-0027 Oslo, Norway
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33
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Vidal AE, Harkiolaki M, Gallego C, Castillo-Acosta VM, Ruiz-Pérez LM, Wilson K, González-Pacanowska D. Crystal Structure and DNA Repair Activities of the AP Endonuclease from Leishmania major. J Mol Biol 2007; 373:827-38. [PMID: 17870086 DOI: 10.1016/j.jmb.2007.08.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Revised: 07/24/2007] [Accepted: 08/01/2007] [Indexed: 12/31/2022]
Abstract
Apurinic/apyrimidinic endonucleases initiate the repair of abasic sites produced either spontaneously, from attack of bases by reactive oxygen species or as intermediates during base excision repair. The catalytic properties and crystal structure of Leishmania major apurinic/apyrimidinic endonuclease are described and compared with those of human APE1 and bacterial exonuclease III. The purified enzyme is shown to possess apurinic/apyrimidinic endonuclease activity of the same order as eukaryotic and prokaryotic counterparts and an equally robust 3'-phosphodiesterase activity. Consistent with this, expression of the L. major endonuclease confers resistance to both methyl methane sulphonate and H2O2 in Escherichia coli repair-deficient mutants while expression of the human homologue only reverts methyl methane sulphonate sensitivity. Structural analyses and modelling of the enzyme-DNA complex demonstrates a high degree of conservation to previously characterized homologues, although subtle differences in the active site geometry might account for the high 3'-phosphodiesterase activity. Our results confirm that the L. major's enzyme is a key element in mediating repair of apurinic/apyrimidinic sites and 3'-blocked termini and therefore must play an important role in the survival of kinetoplastid parasites after exposure to the highly oxidative environment within the host macrophage.
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Affiliation(s)
- Antonio E Vidal
- Instituto de Parasitología y Biomedicina López-Neyra, Consejo Superior de Investigaciones Científicas, Avda. del Conocimiento s/n, 18100 Armilla, Granada, Spain
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34
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Adhikari S, Toretsky JA, Yuan L, Roy R. Magnesium, Essential for Base Excision Repair Enzymes, Inhibits Substrate Binding of N-Methylpurine-DNA Glycosylase. J Biol Chem 2006; 281:29525-32. [PMID: 16901897 DOI: 10.1074/jbc.m602673200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
N-Methylpurine-DNA glycosylase (MPG) initiates base excision repair in DNA by removing a wide variety of alkylated, deaminated, and lipid peroxidation-induced purine adducts. MPG activity and other DNA glycosylases do not have an absolute requirement for a cofactor. In contrast, all downstream activities of major base excision repair proteins, such as apurinic/apyrimidinic endonuclease, DNA polymerase beta, and ligases, require Mg(2+). Here we have demonstrated that Mg(2+) can be significantly inhibitory toward MPG activity depending on its concentration but independent of substrate type. The pre-steady-state kinetics suggests that Mg(2+) at high but physiologic concentrations decreases the amount of active enzyme concentrations. Steady-state inhibition kinetics showed that Mg(2+) affected K(m), but not V(max), and the inhibition could be reversed by EDTA but not by DNA. At low concentration, Mg(2+) stimulated the enzyme activity only with hypoxanthine but not ethenoadenine. Real-time binding experiments using surface plasmon resonance spectroscopy showed that the pronounced inhibition of activity was due to inhibition in substrate binding. Nonetheless, the glycosidic bond cleavage step was not affected. These results altogether suggest that Mg(2+) inhibits MPG activity by abrogating substrate binding. Because Mg(2+) is an absolute requirement for the downstream activities of the major base excision repair enzymes, it may act as a regulator for the base excision repair pathway for efficient and balanced repair of damaged bases, which are often less toxic and/or mutagenic than their subsequent repair product intermediates.
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Affiliation(s)
- Sanjay Adhikari
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA
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35
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Ranneberg-Nilsen T, Bjørås M, Luna L, Slettebakk R, Dale HA, Seeberg E, Rollag H. Human cytomegalovirus infection modulates DNA base excision repair in fibroblast cells. Virology 2006; 348:389-97. [PMID: 16476462 DOI: 10.1016/j.virol.2006.01.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 09/26/2005] [Accepted: 01/03/2006] [Indexed: 10/25/2022]
Abstract
Regulation of DNA repair mechanisms during the viral replication cycle may have consequences for the virus with regards to genomic variability, adaptation, and replication of viral DNA. We have studied the activities and expression patterns of key enzymes involved in the first two steps of base excision repair (BER) of DNA in primary fibroblasts infected by human cytomegalovirus (HCMV). Infected cells were very proficient for removal of uracil and 5' hydrolysis of AP sites (AP endonuclease activity) as compared to the mock-infected cells, suggesting a direct role in generating free ends at uracil lesions in DNA for initiation of viral replication. Furthermore, the capacity to initiate repair of alkylated and oxidized base lesions were reduced in HCMV-infected cells, indicating increased mutation frequencies that could promote genetic variability. We hypothesize that modulation of BER activities may play an important role in HCMV pathogenesis to ensure efficient replication and genomic variation of viral DNA.
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Affiliation(s)
- Toril Ranneberg-Nilsen
- Department of Virology, Institute of Microbiology, University of Oslo, Rikshospitalet, Norway.
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36
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Watanabe T, Blaisdell JO, Wallace SS, Bond JP. Engineering functional changes in Escherichia coli endonuclease III based on phylogenetic and structural analyses. J Biol Chem 2005; 280:34378-84. [PMID: 16096281 DOI: 10.1074/jbc.m504916200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Escherichia coli endonuclease III (EcoNth) plays an important cellular role by removing premutagenic pyrimidine damages produced by reactive oxygen species. EcoNth is a bifunctional enzyme that has DNA glycosylase and apurinic/apyrimidinic lyase activities. Using a phylogeny of natural sequences, we selected to study EcoNth serine 39, aspartate 44, and arginine 184, which are presumed to be in the vicinity of the damaged base in the glycosylase-substrate complex. These three amino acids are highly conserved among Nth orthologs, although not among homologous glycosylases, such as MutY, that have different base specificities and no lyase activity. To examine the role of these amino acids in catalysis, we constructed three mutants of EcoNth, in which Ser39 was replaced with leucine (S39L), Asp44 was replaced with valine (D44V), and Arg184 was replaced with alanine (R184A), which are the corresponding residues in EcoMutY. We showed that EcoNth S39L does not have significant glycosylase activity for oxidized pyrimidines, although it maintained AP lyase activity. In contrast, EcoNth D44V retained glycosylase activity against oxidized pyrimidines, but the apparent rate constant for the lyase activity of EcoNth D44V was significantly lower than that of EcoNth, indicating that Asp44 in EcoNth is required for beta-elimination. Finally, EcoNth R184A maintained lyase activity but exhibited glycosylase specificity different from that of EcoNth. The functional consequences of each of these three substitutions can be rationalized in the context of high resolution protein structures. Thus phylogeny-based scanning mutagenesis has allowed us to identify novel roles for amino acids in the substrate binding pocket of EcoNth in base recognition and/or catalysis.
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Affiliation(s)
- Takashi Watanabe
- Department of Microbiology and Molecular Genetics, The University of Vermont, Burlington, Vermont 05405, USA
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37
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Evans MD, Dizdaroglu M, Cooke MS. Oxidative DNA damage and disease: induction, repair and significance. MUTATION RESEARCH/REVIEWS IN MUTATION RESEARCH 2004; 567:1-61. [PMID: 15341901 DOI: 10.1016/j.mrrev.2003.11.001] [Citation(s) in RCA: 878] [Impact Index Per Article: 43.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2003] [Revised: 11/12/2003] [Accepted: 11/12/2003] [Indexed: 04/08/2023]
Abstract
The generation of reactive oxygen species may be both beneficial to cells, performing a function in inter- and intracellular signalling, and detrimental, modifying cellular biomolecules, accumulation of which has been associated with numerous diseases. Of the molecules subject to oxidative modification, DNA has received the greatest attention, with biomarkers of exposure and effect closest to validation. Despite nearly a quarter of a century of study, and a large number of base- and sugar-derived DNA lesions having been identified, the majority of studies have focussed upon the guanine modification, 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-OH-dG). For the most part, the biological significance of other lesions has not, as yet, been investigated. In contrast, the description and characterisation of enzyme systems responsible for repairing oxidative DNA base damage is growing rapidly, being the subject of intense study. However, there remain notable gaps in our knowledge of which repair proteins remove which lesions, plus, as more lesions identified, new processes/substrates need to be determined. There are many reports describing elevated levels of oxidatively modified DNA lesions, in various biological matrices, in a plethora of diseases; however, for the majority of these the association could merely be coincidental, and more detailed studies are required. Nevertheless, even based simply upon reports of studies investigating the potential role of 8-OH-dG in disease, the weight of evidence strongly suggests a link between such damage and the pathogenesis of disease. However, exact roles remain to be elucidated.
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Affiliation(s)
- Mark D Evans
- Oxidative Stress Group, Department of Clinical Biochemistry, University of Leicester, Leicester Royal Infirmary, University Hospitals of Leicester NHS Trust, LE2 7LX, UK
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38
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Falnes PØ, Bjørås M, Aas PA, Sundheim O, Seeberg E. Substrate specificities of bacterial and human AlkB proteins. Nucleic Acids Res 2004; 32:3456-61. [PMID: 15229293 PMCID: PMC443531 DOI: 10.1093/nar/gkh655] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Methylating agents introduce cytotoxic 1-methyladenine (1-meA) and 3-methylcytosine (3-meC) residues into nucleic acids, and it was recently demonstrated that the Escherichia coli AlkB protein and two human homologues, hABH2 and hABH3, can remove these lesions from DNA by oxidative demethylation. Moreover, AlkB and hABH3 were also found to remove 1-meA and 3-meC from RNA, suggesting that cellular RNA repair can occur. We have here studied the preference of AlkB, hABH2 and hABH3 for single-stranded DNA (ssDNA) or double-stranded DNA (dsDNA), and show that AlkB and hABH3 prefer ssDNA, while hABH2 prefers dsDNA. This was consistently observed with three different oligonucleotide substrates, implying that the specificity for single-stranded versus double-stranded DNA is sequence independent. The dsDNA preference of hABH2 was observed only in the presence of magnesium. The activity of the enzymes on single-stranded RNA (ssRNA), double-stranded RNA (dsRNA) and DNA/RNA hybrids was also investigated, and the results generally confirm the notion that while AlkB and hABH3 tend to prefer single-stranded nucleic acids, hABH2 is more active on double-stranded substrates. These results may contribute to identifying the main substrates of bacterial and human AlkB proteins in vivo.
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Affiliation(s)
- Pål Ø Falnes
- Centre for Molecular Biology and Neuroscience, Institute of Medical Microbiology, Rikshospitalet University Hospital, 0027 Oslo, Norway.
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39
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Meadows KL, Song B, Doetsch PW. Characterization of AP lyase activities of Saccharomyces cerevisiae Ntg1p and Ntg2p: implications for biological function. Nucleic Acids Res 2003; 31:5560-7. [PMID: 14500818 PMCID: PMC206450 DOI: 10.1093/nar/gkg749] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Saccharomyces cerevisiae possesses two Escherichia coli endonuclease III homologs, NTG1 and NTG2, whose gene products function in the base excision repair pathway and initiate removal of a variety of oxidized pyrimidines from DNA. Although the glycosylase activity of these proteins has been well studied, the in vivo importance of the AP lyase activity has not been determined. Previous genetic studies have suggested that the AP lyase activities of Ntg1p and Ntg2p may be major contributors in the initial processing of abasic sites. We conducted a biochemical characterization of the AP lyase activities of Ntg1p and Ntg2p via a series of kinetic experiments. Such studies were designed to determine if Ntg1p and Ntg2p prefer specific bases located opposite abasic sites and whether these lesions are processed with a catalytic efficiency similar to Apn1p, the major hydrolytic AP endonuclease of yeast. Our results indicate that Ntg1p and Ntg2p are equally effective in processing four types of abasic site-containing substrates. Certain abasic site substrates were processed with greater catalytic efficiency than others, a situation similar to Apn1p processing of such substrates. These biochemical studies strongly support an important biological role for Ntg1p and Ntg2p in the initial processing of abasic sites and maintenance of genomic stability.
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Affiliation(s)
- Kellen L Meadows
- Graduate Program in Genetics and Molecular Biology, Emory University, Atlanta, GA 30322, USA
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40
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Rogers PA, Eide L, Klungland A, Ding H. Reversible inactivation of E. coli endonuclease III via modification of its [4Fe-4S] cluster by nitric oxide. DNA Repair (Amst) 2003; 2:809-17. [PMID: 12826281 DOI: 10.1016/s1568-7864(03)00065-x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Endonuclease III, a highly conserved enzyme initiating the base excision repair of oxidized DNA bases, hosts a [4Fe-4S] cluster. Unlike many other iron-sulfur clusters, the [4Fe-4S] cluster of endonuclease III is stable and resistant to both oxidation and reduction. Here we show that the [4Fe-4S] cluster of the E. coli endonuclease III can be readily modified by nitric oxide forming the protein-bound dinitrosyl iron complex in vitro and in vivo. Modification of the [4Fe-4S] cluster completely inhibits the DNA glycosylase activity of the endonuclease III. Remarkably, the enzymatic activity is restored when the [4Fe-4S] cluster is re-assembled in the endonuclease III dinitrosyl iron complex with L-cysteine, cysteine desulfurase (IscS) and ferrous iron in vitro. Furthermore, the nitric oxide-modified [4Fe-4S] cluster in endonuclease III is efficiently repaired in aerobically growing E. coli cells, and this repair does not require new protein synthesis. These results suggest that the E. coli endonuclease III can be reversibly inactivated by nitric oxide via modification of its [4Fe-4S] cluster.
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Affiliation(s)
- Paul A Rogers
- Department of Biological Sciences, 202 Life Sciences Building, Louisiana State University, Baton Rouge, LA , USA
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41
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Abstract
Oxidative DNA damage is an inevitable consequence of cellular metabolism, with a propensity for increased levels following toxic insult. Although more than 20 base lesions have been identified, only a fraction of these have received appreciable study, most notably 8-oxo-2'deoxyguanosine. This lesion has been the focus of intense research interest and been ascribed much importance, largely to the detriment of other lesions. The present work reviews the basis for the biological significance of oxidative DNA damage, drawing attention to the multiplicity of proteins with repair activities along with a number of poorly considered effects of damage. Given the plethora of (often contradictory) reports describing pathological conditions in which levels of oxidative DNA damage have been measured, this review critically addresses the extent to which the in vitro significance of such damage has relevance for the pathogenesis of disease. It is suggested that some shortcomings associated with biomarkers, along with gaps in our knowledge, may be responsible for the failure to produce consistent and definitive results when applied to understanding the role of DNA damage in disease, highlighting the need for further studies.
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Affiliation(s)
- Marcus S Cooke
- Oxidative Stress Group, Department of Clinical Biochemistry, University of Leicester, Leicester Royal Infirmary, University Hospitals of Leicester NHS Trust, Leicester, LE2 7LX, UK.
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42
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Rosenquist TA, Zaika E, Fernandes AS, Zharkov DO, Miller H, Grollman AP. The novel DNA glycosylase, NEIL1, protects mammalian cells from radiation-mediated cell death. DNA Repair (Amst) 2003; 2:581-91. [PMID: 12713815 DOI: 10.1016/s1568-7864(03)00025-9] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
DNA damage mediated by reactive oxygen species generates miscoding and blocking lesions that may lead to mutations or cell death. Base excision repair (BER) constitutes a universal mechanism for removing oxidatively damaged bases and restoring the integrity of genomic DNA. In Escherichia coli, the DNA glycosylases Nei, Fpg, and Nth initiate BER of oxidative lesions; OGG1 and NTH1 proteins fulfill a similar function in mammalian cells. Three human genes, designated NEIL1, NEIL2 and NEIL3, encode proteins that contain sequence homologies to Nei and Fpg. We have cloned the corresponding mouse genes and have overexpressed and purified mNeil1, a DNA glycosylase that efficiently removes a wide spectrum of mutagenic and cytotoxic DNA lesions. These lesions include the two cis-thymineglycol(Tg) stereoisomers, guanine- and adenine-derived formamidopyrimidines, and 5,6-dihydrouracil. Two of these lesions, fapyA and 5S,6R thymine glycol, are not excised by mOgg1 or mNth1. We have also used RNA interference technology to establish embryonic stem cell lines deficient in Neil1 protein and showed them to be sensitive to low levels of gamma-irradiation. The results of these studies suggest that Neil1 is an essential component of base excision repair in mammalian cells; its presence may contribute to the redundant repair capacity observed in Ogg1 -/- and Nth1 -/- mice.
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Affiliation(s)
- Thomas A Rosenquist
- Department of Pharmacological Sciences, SUNY Stony Brook, Stony Brook, NY 11794, USA.
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43
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Marenstein DR, Chan MK, Altamirano A, Basu AK, Boorstein RJ, Cunningham RP, Teebor GW. Substrate specificity of human endonuclease III (hNTH1). Effect of human APE1 on hNTH1 activity. J Biol Chem 2003; 278:9005-12. [PMID: 12519758 DOI: 10.1074/jbc.m212168200] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Base excision repair of oxidized pyrimidines in human DNA is initiated by the DNA N-glycosylase/apurinic/apyrimidinic (AP) lyase, human NTH1 (hNTH1), the homolog of Escherichia coli endonuclease III (Nth). In contrast to Nth, the DNA N-glycosylase activity of hNTH1 is 7-fold greater than its AP lyase activity when the DNA substrate contains a thymine glycol (Tg) opposite adenine (Tg:A) (Marenstein, D. R., Ocampo, M. T. A., Chan, M. K., Altamirano, A., Basu, A. K., Boorstein, R. J., Cunningham, R. P., and Teebor, G. W. (2001) J. Biol. Chem. 276, 21242-21249). When Tg is opposite guanine (Tg:G), the two activities are of the same specific activity as the AP lyase activity of hNTH1 against Tg:A (Ocampo, M. T. A., Chaung, W., Marenstein, D. R., Chan, M. K., Altamirano, A., Basu, A. K., Boorstein, R. J., Cunningham, R. P., and Teebor, G. W. (2002) Mol. Cell. Biol. 22, 6111-6121). We demonstrate here that hNTH1 was inhibited by the product of its DNA N-glycosylase activity directed against Tg:G, the AP:G site. In contrast, hNTH1 was not as inhibited by the AP:A site arising from release of Tg from Tg:A. Addition of human APE1 (AP endonuclease-1) increased dissociation of hNTH1 from the DNA N-glycosylase-generated AP:A site, resulting in abrogation of AP lyase activity and an increase in turnover of the DNA N-glycosylase activity of hNTH1. Addition of APE1 did not abrogate hNTH1 AP lyase activity against Tg:G. The stimulatory protein YB-1 (Marenstein et al.), added to APE1, resulted in an additive increase in both activities of hNTH1 regardless of base pairing. Tg:A is formed by oxidative attack on thymine opposite adenine. Tg:G is formed by oxidative attack on 5-methylcytosine opposite guanine (Zuo, S., Boorstein, R. J., and Teebor, G. W. (1995) Nucleic Acids Res. 23, 3239-3243). It is possible that the in vitro substrate selectivity of mammalian NTH1 and the concomitant selective stimulation of activity by APE1 are indicative of selective repair of oxidative damage in different regions of the genome.
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Affiliation(s)
- Dina R Marenstein
- Department of Pathology and the Kaplan Comprehensive Cancer Center, New York University School of Medicine, New York, New York 10016, USA
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Olsen AK, Duale N, Bjørås M, Larsen CT, Wiger R, Holme JA, Seeberg EC, Brunborg G. Limited repair of 8-hydroxy-7,8-dihydroguanine residues in human testicular cells. Nucleic Acids Res 2003; 31:1351-63. [PMID: 12582255 PMCID: PMC150234 DOI: 10.1093/nar/gkg216] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Oxidative damage in testicular DNA is associated with poor semen quality, reduced fertility and increased risk of stillbirths and birth defects. These DNA lesions are predominantly removed by base excision repair. Cellular extracts from human and rat testicular cells and three enriched populations of rat male germ cells (primary spermatocytes, round spermatids and elongating/elongated spermatids) all showed proficient excision/incision of 5-hydroxycytosine, thymine glycol and 2,6-diamino-4-hydroxy-5-formamidopyrimidine. DNA containing 8-oxo-7,8-dihydroguanine was excised poorly by human testicular cell extracts, although 8-oxoguanine-DNA glycosylase-1 (hOGG1) was present in human testicular cells, at levels that varied markedly between 13 individuals. This excision was as low as with human mononuclear blood cell extracts. The level of endonuclease III homologue-1 (NTH1), which excises oxidised pyrimidines, was higher in testicular than in somatic cells of both species. Cellular repair studies of lesions recognised by formamidopyrimidine-DNA glycosylase (Fpg) or endonuclease III (Nth) were assayed with alkaline elution and the Comet assay. Consistent with the enzymatic activities, human testicular cells showed poor removal of Fpg-sensitive lesions but efficient repair of Nth-sensitive lesions. Rat testicular cells efficiently repaired both Fpg- and Nth-sensitive lesions. In conclusion, human testicular cells have limited capacity to repair important oxidative DNA lesions, which could lead to impaired reproduction and de novo mutations.
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Affiliation(s)
- Ann-Karin Olsen
- Department of Chemical Toxicology, Division of Environmental Medicine, Norwegian Institute of Public Health, PO Box 4404 Nydalen, N-0403 Oslo, Norway
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Abstract
A number of intrinsic and extrinsic mutagens induce structural damage in cellular DNA. These DNA damages are cytotoxic, miscoding or both and are believed to be at the origin of cell lethality, tissue degeneration, ageing and cancer. In order to counteract immediately the deleterious effects of such lesions, leading to genomic instability, cells have evolved a number of DNA repair mechanisms including the direct reversal of the lesion, sanitation of the dNTPs pools, mismatch repair and several DNA excision pathways including the base excision repair (BER) nucleotide excision repair (NER) and the nucleotide incision repair (NIR). These repair pathways are universally present in living cells and extremely well conserved. This review is focused on the repair of lesions induced by free radicals and ionising radiation. The BER pathway removes most of these DNA lesions, although recently it was shown that other pathways would also be efficient in the removal of oxidised bases. In the BER pathway the process is initiated by a DNA glycosylase excising the modified and mismatched base by hydrolysis of the glycosidic bond between the base and the deoxyribose of the DNA, generating a free base and an abasic site (AP-site) which in turn is repaired since it is cytotoxic and mutagenic.
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Affiliation(s)
- Laurent Gros
- Groupe Réparation de l'ADN, UMR 8532 CNRS, LBPA-ENS Cachan, Institut Gustave Roussy, 39, rue Camille Desmoulins, 94805 Villejuif Cedex, France
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Morland I, Rolseth V, Luna L, Rognes T, Bjørås M, Seeberg E. Human DNA glycosylases of the bacterial Fpg/MutM superfamily: an alternative pathway for the repair of 8-oxoguanine and other oxidation products in DNA. Nucleic Acids Res 2002; 30:4926-36. [PMID: 12433996 PMCID: PMC137166 DOI: 10.1093/nar/gkf618] [Citation(s) in RCA: 216] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The mild phenotype associated with targeted disruption of the mouse OGG1 and NTH1 genes has been attributed to the existence of back-up activities and/or alternative pathways for the removal of oxidised DNA bases. We have characterised two new genes in human cells that encode DNA glycosylases, homologous to the bacterial Fpg (MutM)/Nei class of enzymes, capable of removing lesions that are substrates for both hOGG1 and hNTH1. One gene, designated HFPG1, showed ubiquitous expression in all tissues examined whereas the second gene, HFPG2, was only expressed at detectable levels in the thymus and testis. Transient transfections of HeLa cells with fusions of the cDNAs to EGFP revealed intracellular sorting to the nucleus with accumulation in the nucleoli for hFPG1, while hFPG2 co-localised with the 30 kDa subunit of RPA. hFPG1 was purified and shown to act on DNA substrates containing 8-oxoguanine, 5-hydroxycytosine and abasic sites. Removal of 8-oxoguanine, but not cleavage at abasic sites, was opposite base-dependent, with 8-oxoG:C being the preferred substrate and negligible activity towards 8-oxoG:A. It thus appears that hFPG1 has properties similar to mammalian OGG1 in preventing mutations arising from misincorporation of A across 8-oxoG and could function as a back-up repair activity for OGG1 in ogg1(-/-) mice.
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Affiliation(s)
- Ingrid Morland
- Department of Molecular Biology, Institute of Medical Microbiology, University of Oslo, Rikshospitalet, 0027 Oslo, Norway
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Miyabe I, Zhang QM, Kino K, Sugiyama H, Takao M, Yasui A, Yonei S. Identification of 5-formyluracil DNA glycosylase activity of human hNTH1 protein. Nucleic Acids Res 2002; 30:3443-8. [PMID: 12140329 PMCID: PMC137084 DOI: 10.1093/nar/gkf460] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
5-formyluracil (5-foU) is a potentially mutagenic lesion of thymine produced in DNA by ionizing radiation and various chemical oxidants. The elucidation of repair mechanisms for 5-foU will yield important insights into the biological consequences of the lesion. Recently, we reported that 5-foU is recognized and removed from DNA by Escherichia coli enzymes Nth (endonuclease III), Nei (endonuclease VIII) and MutM (formamidopyrimidine DNA glycosylase). Human cells have been shown to have enzymatic activities that release 5-foU from X-ray-irradiated DNA, but the molecular identities of these activities are not yet known. In this study, we demonstrate that human hNTH1 (endonuclease III homolog) has a DNA glycosylase/AP lyase activity that recognizes 5-foU in DNA and removes it. hNTH1 cleaved 5-foU-containing duplex oligonucleotides via a beta-elimination reaction. It formed Schiff base intermediates with 5-foU-containing oligonucleotides. Furthermore, hNTH1 cleaved duplex oligonucleotides containing all of the 5-foU/N pairs (N = G, A, T or C). The specific activities of hNTH1 for cleavage of oligonucleotides containing 5-foU and thymine glycol were 0.011 and 0.045 nM/min/ng protein, respectively. These results indicate that hNTH1 has DNA glycosylase activity with the potential to recognize 5-foU in DNA and remove it in human cells.
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Affiliation(s)
- Izumi Miyabe
- Laboratory of Radiation Biology, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
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Abstract
The principal oxidized cytosine bases, uracil glycol, 5-hydroxycytosine, and 5-hydroxyuracil, are readily bypassed, miscode, and are thus important premutagenic lesions. Similarly the principal oxidation product of guanine, 8-oxoguanine, miscodes with A and is a premutagenic lesion. Most of the thymine and adenine products that retain their ring structure primarily pair with their cognate bases and are not potent premutagenic lesions. Although thymine glycol pairs with its cognate base and is not mutagenic it significantly distorts the DNA molecule and is a lethal lesion. Ring fragmentation, ring contraction, and ring open products of both pyrimidines and purines block DNA polymerases and are potentially lethal lesions. Although these breakdown products have the potential to mispair during translesion synthesis, the mutational spectra of prokaryotic mutants defective in the pyrimidine-specific and/or purine-specific DNA glycosylases do not reflect that expected of the breakdown products. Taken together, the data suggest that the principal biological consequences of endogenously produced and unrepaired free radical-damaged DNA bases are mutations.
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Affiliation(s)
- Susan S Wallace
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, The University of Vermont, Burlington, VT 05405-0068, USA.
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