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Ramesh J, Gopalakrishnan RM, Nguyen THA, Lai SK, Li HY, Kim PS, Kutzner A, Inoue N, Heese K. Deciphering the molecular landscape of the FAM72 gene family: Implications for stem cell biology and cancer. Neurochem Int 2024; 180:105853. [PMID: 39236808 DOI: 10.1016/j.neuint.2024.105853] [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: 06/27/2024] [Revised: 08/29/2024] [Accepted: 09/02/2024] [Indexed: 09/07/2024]
Abstract
Family with sequence similarity 72 (FAM72) is a protein-coding gene family located on chromosome 1 in humans, uniquely featuring four paralogs: FAM72A, FAM72B, FAM72C, and FAM72D. While FAM72's presence as a gene pair with the SLIT-ROBO Rho GTPase-activating protein 2 (SRGAP2) is intriguing, its functional roles, particularly in neural stem cells, remain incompletely understood. This review explores the distinct characteristics of FAM72, shedding light on its expression patterns, potential roles in cell cycle regulation, stem cell renewal and implications in neurogenesis and tumorigenesis.
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Affiliation(s)
- Janani Ramesh
- Department of Medical Biochemistry, Dr ALM Postgraduate Institute of Biomedical Sciences, University of Madras, Chennai, Tamil Nadu, 600-113, India.
| | - Raja Mohan Gopalakrishnan
- Centre for Advanced Studies in Botany, University of Madras, Guindy Campus, Chennai, Tamil Nadu, 600-025, India.
| | - Tuan Hoang Anh Nguyen
- Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 133-791, Republic of Korea.
| | - Soak-Kuan Lai
- School of Biological Sciences, College of Science, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637-551, Singapore.
| | - Hoi-Yeung Li
- School of Biological Sciences, College of Science, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637-551, Singapore.
| | - Pok-Son Kim
- Department of Information Security, Cryptology, and Mathematics, Kookmin University, Seoul, 136-702, Republic of Korea.
| | - Arne Kutzner
- Department of Information Systems, College of Computer Science, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 133-791, Republic of Korea.
| | - Noriko Inoue
- Osaka University Institute for Sports and Global Health, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Klaus Heese
- Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 133-791, Republic of Korea.
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Kulkarni RS, Greenwood SN, Weiser BP. Assay design for analysis of human uracil DNA glycosylase. Methods Enzymol 2022; 679:343-362. [PMID: 36682870 DOI: 10.1016/bs.mie.2022.07.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Human uracil DNA glycosylase (UNG2) is an enzyme whose primary function is to remove uracil bases from genomic DNA. UNG2 activity is critical when uracil bases are elevated in DNA during class switch recombination and somatic hypermutation, and additionally, UNG2 affects the efficacy of thymidylate synthase inhibitors that increase genomic uracil levels. Here, we summarize the enzymatic properties of UNG2 and its mitochondrial analog UNG1. To facilitate studies on the activity of these highly conserved proteins, we discuss three fluorescence-based enzyme assays that have informed much of our understanding on UNG2 function. The assays use synthetic DNA oligonucleotide substrates with uracil bases incorporated in the DNA, and the substrates can be single-stranded, double-stranded, or form other structures such as DNA hairpins or junctions. The fluorescence signal reporting uracil base excision by UNG2 is detected in different ways: (1) Excision of uracil from end-labeled oligonucleotides is measured by visualizing UNG2 reaction products with denaturing PAGE; (2) Uracil excision from dsDNA substrates is detected in solution by base pairing uracil with 2-aminopurine, whose intrinsic fluorescence is enhanced upon uracil excision; or (3) UNG2 excision of uracil from a hairpin molecular beacon substrate changes the structure of the substrate and turns on fluorescence by relieving a fluorescence quench. In addition to their utility in characterizing UNG2 properties, these assays are being adapted to discover inhibitors of the enzyme and to determine how protein-protein interactions affect UNG2 function.
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Affiliation(s)
- Rashmi S Kulkarni
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ, United States
| | - Sharon N Greenwood
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ, United States
| | - Brian P Weiser
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ, United States.
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Carvalho G, Repolês BM, Mendes I, Wanrooij PH. Mitochondrial DNA Instability in Mammalian Cells. Antioxid Redox Signal 2022; 36:885-905. [PMID: 34015960 PMCID: PMC9127837 DOI: 10.1089/ars.2021.0091] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 05/11/2021] [Indexed: 02/06/2023]
Abstract
Significance: The small, multicopy mitochondrial genome (mitochondrial DNA [mtDNA]) is essential for efficient energy production, as alterations in its coding information or a decrease in its copy number disrupt mitochondrial ATP synthesis. However, the mitochondrial replication machinery encounters numerous challenges that may limit its ability to duplicate this important genome and that jeopardize mtDNA stability, including various lesions in the DNA template, topological stress, and an insufficient nucleotide supply. Recent Advances: An ever-growing array of DNA repair or maintenance factors are being reported to localize to the mitochondria. We review current knowledge regarding the mitochondrial factors that may contribute to the tolerance or repair of various types of changes in the mitochondrial genome, such as base damage, incorporated ribonucleotides, and strand breaks. We also discuss the newly discovered link between mtDNA instability and activation of the innate immune response. Critical Issues: By which mechanisms do mitochondria respond to challenges that threaten mtDNA maintenance? What types of mtDNA damage are repaired, and when are the affected molecules degraded instead? And, finally, which forms of mtDNA instability trigger an immune response, and how? Future Directions: Further work is required to understand the contribution of the DNA repair and damage-tolerance factors present in the mitochondrial compartment, as well as the balance between mtDNA repair and degradation. Finally, efforts to understand the events underlying mtDNA release into the cytosol are warranted. Pursuing these and many related avenues can improve our understanding of what goes wrong in mitochondrial disease. Antioxid. Redox Signal. 36, 885-905.
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Affiliation(s)
- Gustavo Carvalho
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Bruno Marçal Repolês
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Isabela Mendes
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Paulina H. Wanrooij
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
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4
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Renganathan S, Pramanik S, Ekambaram R, Kutzner A, Kim PS, Heese K. Identification of a Chemotherapeutic Lead Molecule for the Potential Disruption of the FAM72A-UNG2 Interaction to Interfere with Genome Stability, Centromere Formation, and Genome Editing. Cancers (Basel) 2021; 13:5870. [PMID: 34831023 PMCID: PMC8616359 DOI: 10.3390/cancers13225870] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 11/15/2021] [Accepted: 11/20/2021] [Indexed: 01/05/2023] Open
Abstract
Family with sequence similarity 72 A (FAM72A) is a pivotal mitosis-promoting factor that is highly expressed in various types of cancer. FAM72A interacts with the uracil-DNA glycosylase UNG2 to prevent mutagenesis by eliminating uracil from DNA molecules through cleaving the N-glycosylic bond and initiating the base excision repair pathway, thus maintaining genome integrity. In the present study, we determined a specific FAM72A-UNG2 heterodimer protein interaction using molecular docking and dynamics. In addition, through in silico screening, we identified withaferin B as a molecule that can specifically prevent the FAM72A-UNG2 interaction by blocking its cell signaling pathways. Our results provide an excellent basis for possible therapeutic approaches in the clinical treatment of cancer.
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Affiliation(s)
- Senthil Renganathan
- Department of Bioinformatics, Marudupandiyar College, Thanjavur 613403, India;
| | - Subrata Pramanik
- Department of Biology, Life Science Centre, School of Science and Technology, Örebro University, 701-82 Örebro, Sweden;
| | | | - Arne Kutzner
- Department of Information Systems, College of Engineering, Hanyang University, Seoul 133-791, Korea;
| | - Pok-Son Kim
- Department of Information Security, Cryptology, and Mathematics, Kookmin University, Seoul 136-702, Korea;
| | - Klaus Heese
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 133-791, Korea
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Liu ZC, Wng Q, Zheng Q, Zhao WL, Chen C, Ruan LY, Xu H, Meng HH, Zhao WL, Liu WY, Zhong JG, Luo BZX, Norbu K, Zhou F, Wang JS, Feng X. Acute hepatotoxicity and nephrotoxicity risk assessment of the Tibetan medicine 25 flavors of the turquoise pill based on 1H-NMR metabonomics. JOURNAL OF ETHNOPHARMACOLOGY 2021; 279:113916. [PMID: 33571615 DOI: 10.1016/j.jep.2021.113916] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 02/04/2021] [Accepted: 02/05/2021] [Indexed: 06/12/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE 25 flavors of the turquoise pill, a traditional Tibetan medicine for the treatment of various types of hepatitis, has not been investigated on its safety, especially the component mineral turquoise, which is believed to be essential but worried for its potential toxicity. AIM OF THE STUDY To explore the potential acute toxicity and function of 25 flavors of the turquoise pill and turquoise, the possible mechanism of the effects of turquoise and 25 flavors of the turquoise pill were systematically studied based on 1H NMR metabolomics. MATERIALS AND METHODS The rats were administered with turquoise and 25 flavors of the turquoise pill by gavage for 7 days, and samples of serum, liver, and kidney were collected. The potential toxicity and function of turquoise and 25 flavors of the turquoise pill on the liver and kidney of SD rats were evaluated by 1H NMR metabonomics, histopathology, and biochemical indexes. RESULTS The results demonstrated that 25 flavors of the turquoise pill could scavenge free oxygen radicals, strengthen aerobic respiration and inhibit glycolysis in the liver. It did not cause oxidative stress in the kidney with no obvious damage. By modulation of branched-chain amino acids (BCAAs), 25 flavors of the turquoise pill can improve the utilization of glucose and promote aerobic respiration of the kidney. CONCLUSION Considering the high dosage and short duration used in this study relative to their typical clinical usage, administration of 25 flavors of the turquoise pill and its component mineral turquoise are safe to livers and kidneys.
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Affiliation(s)
- Zhi-Chao Liu
- Center of Molecular Metabolism, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing, 210094, China
| | - Qian Wng
- Beijing Hospital of Tibetan Medicine, China Tibetology Research Center, Beijing, 100029, China
| | - Qi Zheng
- Center of Molecular Metabolism, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing, 210094, China
| | - Wen-Li Zhao
- Center of Molecular Metabolism, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing, 210094, China
| | - Cheng Chen
- Center of Molecular Metabolism, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing, 210094, China
| | - Ling-Yu Ruan
- Center of Molecular Metabolism, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing, 210094, China
| | - Han Xu
- Center of Molecular Metabolism, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing, 210094, China
| | - Hui-Hui Meng
- Center of Molecular Metabolism, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing, 210094, China
| | - Wen-Long Zhao
- Center of Molecular Metabolism, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing, 210094, China
| | - Wen-Ya Liu
- Center of Molecular Metabolism, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing, 210094, China
| | - Jia-Ge Zhong
- Beijing Hospital of Tibetan Medicine, China Tibetology Research Center, Beijing, 100029, China
| | - Bu-Zha-Xi Luo
- Beijing Hospital of Tibetan Medicine, China Tibetology Research Center, Beijing, 100029, China
| | - Kelsang Norbu
- Tibet Ganlu Tibetan Medicine Co., Ltd, Lhasa, 851400, China
| | - Feng Zhou
- Tibet Ganlu Tibetan Medicine Co., Ltd, Lhasa, 851400, China
| | - Jun-Song Wang
- Center of Molecular Metabolism, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing, 210094, China.
| | - Xin Feng
- Beijing Hospital of Tibetan Medicine, China Tibetology Research Center, Beijing, 100029, China.
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6
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Bao Y, Tong L, Song B, Liu G, Zhu Q, Lu X, Zhang J, Lu YF, Wen H, Tian Y, Sun Y, Zhu WG. UNG2 deacetylation confers cancer cell resistance to hydrogen peroxide-induced cytotoxicity. Free Radic Biol Med 2020; 160:403-417. [PMID: 32649985 DOI: 10.1016/j.freeradbiomed.2020.06.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 05/29/2020] [Accepted: 06/12/2020] [Indexed: 02/06/2023]
Abstract
Cancer therapeutics produce reactive oxygen species (ROS) that damage the cancer genome and lead to cell death. However, cancer cells can resist ROS-induced cytotoxicity and survive. We show that nuclear-localized uracil-DNA N-glycosylase isoform 2 (UNG2) has a critical role in preventing ROS-induced DNA damage and enabling cancer-cell resistance. Under physiological conditions, UNG2 is targeted for rapid degradation via an interaction with the E3 ligase UHRF1. In response to ROS, however, UNG2 protein in cancer cells exhibits a remarkably extended half-life. Upon ROS exposure, UNG2 is deacetylated at lysine 78 by histone deacetylases, which prevents the UNG2-UHRF1 interaction. Accumulated UNG2 protein can thus excise the base damaged by ROS and enable the cell to survive these otherwise toxic conditions. Consequently, combining HDAC inhibitors (to permit UNG2 degradation) with genotoxic agents (to produce cytotoxic cellular levels of ROS) leads to a robust synergistic killing effect in cancer cells in vitro. Altogether, these data support the application of a novel approach to cancer treatment based on promoting UNG2 degradation by altering its acetylation status using an HDAC inhibitor.
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Affiliation(s)
- Yantao Bao
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China; International Cancer Center, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Lili Tong
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Boyan Song
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Ge Liu
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Qian Zhu
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Xiaopeng Lu
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Jun Zhang
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Ya-Fei Lu
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - He Wen
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Yuan Tian
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Yujie Sun
- Department of Cell Biology, Nanjing Medical University, Nanjing, 211166, China
| | - Wei-Guo Zhu
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China; International Cancer Center, Shenzhen University School of Medicine, Shenzhen, 518055, China; Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China; Shenzhen Bay Laboratory, Shenzhen University School of Medicine, Shenzhen, 518055, China.
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7
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Kara H, Chazal N, Bouaziz S. Is Uracil-DNA Glycosylase UNG2 a New Cellular Weapon Against HIV-1? Curr HIV Res 2020; 17:148-160. [PMID: 31433761 DOI: 10.2174/1570162x17666190821154331] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Revised: 08/01/2019] [Accepted: 08/09/2019] [Indexed: 01/12/2023]
Abstract
Uracil-DNA glycosylase-2 (UNG2) is a DNA repair protein that removes uracil from single and double-stranded DNA through a basic excision repair process. UNG2 is packaged into new virions by interaction with integrase (IN) and is needed during the early stages of the replication cycle. UNG2 appears to play both a positive and negative role during HIV-1 replication; UNG2 improves the fidelity of reverse transcription but the nuclear isoform of UNG2 participates in the degradation of cDNA and the persistence of the cellular genome by repairing its uracil mismatches. In addition, UNG2 is neutralized by Vpr, which redirects it to the proteasome for degradation, suggesting that UNG2 may be a new cellular restriction factor. So far, we have not understood why HIV-1 imports UNG2 via its IN and why it causes degradation of endogenous UNG2 by redirecting it to the proteasome via Vpr. In this review, we propose to discuss the ambiguous role of UNG2 during the HIV-1 replication cycle.
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Affiliation(s)
- Hesna Kara
- Cibles Therapeutiques et Conception de Medicaments (CiTCoM), CNRS UMR8038, Faculte des Sciences Pharmaceutiques et Biologiques, Universite Paris Descartes, Paris, France
| | - Nathalie Chazal
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS UMR9004, Universite de Montpellier, Montpellier, France
| | - Serge Bouaziz
- Cibles Therapeutiques et Conception de Medicaments (CiTCoM), CNRS UMR8038, Faculte des Sciences Pharmaceutiques et Biologiques, Universite Paris Descartes, Paris, France
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8
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Ferrando B, Furlanetto ALDM, Gredilla R, Havelund JF, Hebelstrup KH, Møller IM, Stevnsner T. DNA repair in plant mitochondria - a complete base excision repair pathway in potato tuber mitochondria. PHYSIOLOGIA PLANTARUM 2019; 166:494-512. [PMID: 30035320 DOI: 10.1111/ppl.12801] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 07/05/2018] [Accepted: 07/11/2018] [Indexed: 05/07/2023]
Abstract
Mitochondria are one of the major sites of reactive oxygen species (ROS) production in the plant cell. ROS can damage DNA, and this damage is in many organisms mainly repaired by the base excision repair (BER) pathway. We know very little about DNA repair in plants especially in the mitochondria. Combining proteomics, bioinformatics, western blot and enzyme assays, we here demonstrate that the complete BER pathway is found in mitochondria isolated from potato (Solanum tuberosum) tubers. The enzyme activities of three DNA glycosylases and an apurinic/apyrimidinic (AP) endonuclease (APE) were characterized with respect to Mg2+ dependence and, in the case of the APE, temperature sensitivity. Evidence for the presence of the DNA polymerase and the DNA ligase, which complete the repair pathway by replacing the excised base and closing the gap, was also obtained. We tested the effect of oxidative stress on the mitochondrial BER pathway by incubating potato tubers under hypoxia. Protein carbonylation increased significantly in hypoxic tuber mitochondria indicative of increased oxidative stress. The activity of two BER enzymes increased significantly in response to this oxidative stress consistent with the role of the BER pathway in the repair of oxidative damage to mitochondrial DNA.
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Affiliation(s)
- Beatriz Ferrando
- Department of Molecular Biology and Genetics, Aarhus University, DK-8000, Aarhus, Denmark
| | - Ana L D M Furlanetto
- Department of Biochemistry and Molecular Biology, Life sciences Sector, Federal University of Paraná, 81531-990, Curitiba, Puerto Rico, Brazil
| | - Ricardo Gredilla
- Department of Molecular Biology and Genetics, Aarhus University, DK-8000, Aarhus, Denmark
- Department of Physiology, Faculty of Medicine, Complutense University, 28040, Madrid, Spain
| | - Jesper F Havelund
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230, Odense, Denmark
| | - Kim H Hebelstrup
- Department of Molecular Biology and Genetics, Aarhus University, DK-4200, Slagelse, Denmark
| | - Ian M Møller
- Department of Molecular Biology and Genetics, Aarhus University, DK-4200, Slagelse, Denmark
| | - Tinna Stevnsner
- Department of Molecular Biology and Genetics, Aarhus University, DK-8000, Aarhus, Denmark
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9
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Baquero JM, Benítez‐Buelga C, Fernández V, Urioste M, García‐Giménez JL, Perona R, Benítez J, Osorio A. A common SNP in the UNG gene decreases ovarian cancer risk in BRCA2 mutation carriers. Mol Oncol 2019; 13:1110-1120. [PMID: 30747491 PMCID: PMC6487686 DOI: 10.1002/1878-0261.12470] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 02/05/2019] [Accepted: 02/05/2019] [Indexed: 12/11/2022] Open
Abstract
Single nucleotide polymorphisms (SNPs) in DNA glycosylase genes involved in the base excision repair (BER) pathway can modify breast and ovarian cancer risk in BRCA1 and BRCA2 mutation carriers. We previously found that SNP rs34259 in the uracil-DNA glycosylase gene (UNG) might decrease ovarian cancer risk in BRCA2 mutation carriers. In the present study, we validated this finding in a larger series of familial breast and ovarian cancer patients to gain insights into how this UNG variant exerts its protective effect. We found that rs34259 is associated with significant UNG downregulation and with lower levels of DNA damage at telomeres. In addition, we found that this SNP is associated with significantly lower oxidative stress susceptibility and lower uracil accumulation at telomeres in BRCA2 mutation carriers. Our findings help to explain the association of this variant with a lower cancer risk in BRCA2 mutation carriers and highlight the importance of genetic changes in BER pathway genes as modifiers of cancer susceptibility for BRCA1 and BRCA2 mutation carriers.
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Affiliation(s)
- Juan Miguel Baquero
- Human Genetics GroupSpanish National Cancer Research Centre (CNIO)MadridSpain
| | | | - Victoria Fernández
- Human Genetics GroupSpanish National Cancer Research Centre (CNIO)MadridSpain
| | - Miguel Urioste
- Spanish Network on Rare Diseases (CIBERER)MadridSpain
- Familial Cancer Clinical UnitSpanish National Cancer Research Centre (CNIO)MadridSpain
| | - Jose Luis García‐Giménez
- Spanish Network on Rare Diseases (CIBERER)MadridSpain
- Department of PhysiologyFaculty of Medicine and DentistryUniversitat de Valencia, Mixed Unit CIPF‐INCLIVASpain
| | - Rosario Perona
- Spanish Network on Rare Diseases (CIBERER)MadridSpain
- Biomedical Research Institute Alberto Sols (CSIC‐UAM)MadridSpain
| | | | - Javier Benítez
- Human Genetics GroupSpanish National Cancer Research Centre (CNIO)MadridSpain
- Spanish Network on Rare Diseases (CIBERER)MadridSpain
- Genotyping Unit (CEGEN)Spanish National Cancer Research Centre (CNIO)MadridSpain
| | - Ana Osorio
- Human Genetics GroupSpanish National Cancer Research Centre (CNIO)MadridSpain
- Spanish Network on Rare Diseases (CIBERER)MadridSpain
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10
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Soltys DT, Pereira CP, Rowies FT, Farfel JM, Grinberg LT, Suemoto CK, Leite RE, Rodriguez RD, Ericson NG, Bielas JH, Souza-Pinto NC. Lower mitochondrial DNA content but not increased mutagenesis associates with decreased base excision repair activity in brains of AD subjects. Neurobiol Aging 2019; 73:161-170. [DOI: 10.1016/j.neurobiolaging.2018.09.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 08/13/2018] [Accepted: 09/13/2018] [Indexed: 12/15/2022]
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11
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Li Y, Liu Z, Zhang Y, Zhao Q, Wang X, Lu P, Zhang H, Wang Z, Dong H, Zhang Z. PEDF protects cardiomyocytes by promoting FUNDC1‑mediated mitophagy via PEDF-R under hypoxic condition. Int J Mol Med 2018; 41:3394-3404. [PMID: 29512692 PMCID: PMC5881750 DOI: 10.3892/ijmm.2018.3536] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2016] [Accepted: 02/15/2018] [Indexed: 01/15/2023] Open
Abstract
Pigment epithelial-derived factor (PEDF) is known to exert diverse physiological activities. Previous studies suggest that hypoxia could induce mitophagy. Astoundingly, under hypoxic condition, we found that PEDF decreased the mitochondrial density of cardiomyocytes. In this study, we evaluated whether PEDF could decrease the mitochondrial density and play a protective role in hypoxic cardiomyocytes via promoting mitophagy. Immunostaining and western blotting were used to analyze mitochondrial density and mitophagy of hypoxic cardiomyocytes. Gas chromatography-mass spectrometry and ELISA were used to analyze levels of palmitic acid and diacylglycerol. Transmission Electron Microscopy was used to detect mitophagy and the mitochondrial density in adult male Sprague-Dawley rat model of acute myocardial infarction. Compared to the control group, we observed that PEDF decreased mitochondrial density through promoting hypoxic cardiomyocyte mitophagy. PEDF increased the levels of palmitic acid and diacylglycerol, and then upregulated the levels of protein kinase Cα (PKC-α) and its activation. Furthermore, inhibition of PKC-α by Go6976 could effectively suppress PEDF-induced mitophagy. Besides, we found that PEDF promoted FUNDC1-mediated cardiomyocyte mitophagy via ULK1, which depended on the activation of PKC-α. Finally, we discovered that mitophagy was increased and mitochondrial density was reduced in adult male Sprague-Dawley rat model of acute myocardial infarction. We concluded that PEDF promotes mitophagy to protect hypoxic cardiomyocytes, through PEDF/PEDF-R/PA/DAG/PKC-α/ULK1/FUNDC1 pathway.
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Affiliation(s)
- Yufeng Li
- Department of Thoracic Cardiovascular Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221006, P.R. China
| | - Zhiwei Liu
- Research Facility Center for Morphology, Xuzhou Medical University, Xuzhou, Jiangsu 221004, P.R. China
| | - Yiqian Zhang
- Department of Thoracic Cardiovascular Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221006, P.R. China
| | - Qixiang Zhao
- Department of Thoracic Cardiovascular Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221006, P.R. China
| | - Xiaoyu Wang
- Department of Thoracic Cardiovascular Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221006, P.R. China
| | - Peng Lu
- Department of Thoracic Cardiovascular Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221006, P.R. China
| | - Hao Zhang
- Department of Thoracic Cardiovascular Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221006, P.R. China
| | - Zhu Wang
- Department of Thoracic Cardiovascular Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221006, P.R. China
| | - Hongyan Dong
- Research Facility Center for Morphology, Xuzhou Medical University, Xuzhou, Jiangsu 221004, P.R. China
| | - Zhongming Zhang
- Department of Thoracic Cardiovascular Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221006, P.R. China
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Zhang L, Reyes A, Wang X. The Role of DNA Repair in Maintaining Mitochondrial DNA Stability. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1038:85-105. [PMID: 29178071 DOI: 10.1007/978-981-10-6674-0_7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Mitochondria are vital double-membrane organelles that act as a "powerhouse" inside the cell and have essential roles to maintain cellular functions, e.g., ATP production, iron-sulfur synthesis metabolism, and steroid synthesis. An important difference with other organelles is that they contain their own mitochondrial DNA (mtDNA). Such powerful organelles are also sensitive to both endogenous and exogenous factors that can cause lesions to their structural components and their mtDNA, resulting in gene mutations and eventually leading to diseases. In this review, we will mainly focus on mammalian mitochondrial DNA repair pathways that safeguard mitochondrial DNA integrity and several important factors involved in the repair process, especially on an essential pathway, base excision repair. We eagerly anticipate to explore more methods to treat related diseases by constantly groping for these complexes and precise repair mechanisms.
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Affiliation(s)
- Linlin Zhang
- Zhongshan Hospital Institute of Clinical Science, Fudan University, Shanghai Medical College, Shanghai, China.
| | - Aurelio Reyes
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK.
| | - Xiangdong Wang
- Zhongshan Hospital Institute of Clinical Science, Fudan University, Shanghai Medical College, Shanghai, China.
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Liu Z, Hu Y, Gong Y, Zhang W, Liu C, Wang Q, Deng H. Hydrogen peroxide mediated mitochondrial UNG1-PRDX3 interaction and UNG1 degradation. Free Radic Biol Med 2016; 99:54-62. [PMID: 27480846 DOI: 10.1016/j.freeradbiomed.2016.07.030] [Citation(s) in RCA: 17] [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: 11/30/2015] [Revised: 07/09/2016] [Accepted: 07/29/2016] [Indexed: 01/13/2023]
Abstract
Isoform 1 of uracil-DNA glycosylase (UNG1) is the major protein for initiating base-excision repair in mitochondria and is in close proximity to the respiratory chain that generates reactive oxygen species (ROS). Effects of ROS on the stability of UNG1 have not been well characterized. In the present study, we found that overexpression of UNG1 enhanced cells' resistance to oxidative stress and protected mitochondrial DNA (mtDNA) from oxidation. Proteomics analysis showed that UNG1 bound to eight proteins in the mitochondria, including PAPSS2, CD70 antigen, and AGR2 under normal growth conditions, whereas UNG1 mainly bound to Peroxiredoxin 3 (PRDX3) via a disulfide linkage under oxidative stress. We further demonstrated that the UNG1-PRDX3 interaction protected UNG1 from ROS-mediated degradation and prevented mtDNA oxidation. Moreover, our results show that ROS-mediated UNG1 degradation was Lon protease 1 (LonP1)-dependent and mitochondrial UNG1 degradation was aggravated by knockdown of PRDX3 expression. Taken together, these results reveal a novel function of UNG1 in the recruitment of PRDX3 to mtDNA under oxidative stress, enabling protection of UNG1 and UNG1-bound DNA from ROS damage and enhancing cell resistance to oxidative stress.
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Affiliation(s)
- Zhilei Liu
- MOE Key Laboratory of Bioinformatics and the Center of Biomedical Analsis, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yadong Hu
- MOE Key Laboratory of Bioinformatics and the Center of Biomedical Analsis, School of Life Sciences, Tsinghua University, Beijing, China; Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
| | - Yiyi Gong
- MOE Key Laboratory of Bioinformatics and the Center of Biomedical Analsis, School of Life Sciences, Tsinghua University, Beijing, China
| | - Wenhao Zhang
- MOE Key Laboratory of Bioinformatics and the Center of Biomedical Analsis, School of Life Sciences, Tsinghua University, Beijing, China
| | - Chongdong Liu
- Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing, China
| | - Qingtao Wang
- Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing, China
| | - Haiteng Deng
- MOE Key Laboratory of Bioinformatics and the Center of Biomedical Analsis, School of Life Sciences, Tsinghua University, Beijing, China.
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Xiao X, Hu M, Liu M, Hu JZ. 1H NMR Metabolomics Study of Spleen from C57BL/6 Mice Exposed to Gamma Radiation. ACTA ACUST UNITED AC 2016; 6:1-11. [PMID: 27019763 PMCID: PMC4807627 DOI: 10.4172/2153-0769.1000165] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Due to the potential risk of accidental exposure to gamma radiation, it’s critical to identify the biomarkers of radiation exposed creatures. In the present study, NMR based metabolomics combined with multivariate data analysis to evaluate the metabolites changed in the C57BL/6 mouse spleen after 4 days whole body exposure to 3.0 Gy and 7.8 Gy gamma radiations. Principal component analysis (PCA) and orthogonal projection to latent structures analysis (OPLS) are employed for classification and identification potential biomarkers associated with gamma irradiation. Two different strategies for NMR spectral data reduction (i.e., spectral binning and spectral deconvolution) are combined with normalize to constant sum and unit weight before multivariate data analysis, respectively. The combination of spectral deconvolution and normalization to unit weight is the best way for identifying discriminatory metabolites between the irradiation and control groups. Normalized to the constant sum may achieve some pseudo biomarkers. PCA and OPLS results shown that the exposed groups can be well separated from the control group. Leucine, 2-aminobutyrate, valine, lactate, arginine, glutathione, 2-oxoglutarate, creatine, tyrosine, phenylalanine, π-methylhistidine, taurine, myoinositol, glycerol and uracil are significantly elevated while ADP is decreased significantly. These significantly changed metabolites are associated with multiple metabolic pathways and may be potential biomarkers in the spleen exposed to gamma irradiation.
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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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16
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Bauer NC, Doetsch PW, Corbett AH. Mechanisms Regulating Protein Localization. Traffic 2015; 16:1039-61. [PMID: 26172624 DOI: 10.1111/tra.12310] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Revised: 07/08/2015] [Accepted: 07/08/2015] [Indexed: 12/23/2022]
Abstract
Cellular functions are dictated by protein content and activity. There are numerous strategies to regulate proteins varying from modulating gene expression to post-translational modifications. One commonly used mode of regulation in eukaryotes is targeted localization. By specifically redirecting the localization of a pool of existing protein, cells can achieve rapid changes in local protein function. Eukaryotic cells have evolved elegant targeting pathways to direct proteins to the appropriate cellular location or locations. Here, we provide a general overview of these localization pathways, with a focus on nuclear and mitochondrial transport, and present a survey of the evolutionarily conserved regulatory strategies identified thus far. We end with a description of several specific examples of proteins that exploit localization as an important mode of regulation.
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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.,Current address: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, 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
| | - 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
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Association between polymorphism of the DNA repair SMUG1 and UNG genes and age-related macular degeneration. Retina 2014; 34:38-47. [PMID: 23714858 DOI: 10.1097/iae.0b013e31829477d8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
PURPOSE To investigate the association between the g.4235T>C (rs2337395) polymorphism of the UNG gene and the c.-31A>G (rs3087404) polymorphism of the SMUG1 gene and the risk of age-related macular degeneration (AMD), as well as modulation of this association by some environmental and lifestyle factors. METHODS Overall, 272 AMD patients and 105 control subjects were enrolled in this study. Both polymorphisms were genotyped by restriction fragment length polymorphism-polymerase chain reaction (PCR-RFLP). RESULTS The C/C genotype of the g.4235T>C polymorphism of the UNG gene was associated with an increased risk of dry AMD (odds ratio, 2.54), whereas the T/T genotype of this polymorphism decreased such risk (odds ratio, 0.41). The presence of the T allele of the g.4235T>C polymorphism and the A allele of the c.-31A>G polymorphism of the SMUG1 gene (odds ratio, 2.17 and 2.18, respectively) was associated with an increased risk of AMD severity, expressed by the comparison of the frequencies of genotypes in the group of patients with wet AMD versus those with dry AMD. Conversely, the C/C genotype of the g.4235T>C polymorphism, the G/G genotype of the c.-31A>G polymorphism, and the C/C-G/G combined genotype of both polymorphisms had a protective effect (odds ratio, 0.48, 0.46, and 0.18; respectively). CONCLUSION The results obtained suggest the potential role of the g.4235T>C and the c.-31A>G polymorphisms in AMD pathogenesis.
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Sykora P, Wilson DM, Bohr VA. Base excision repair in the mammalian brain: implication for age related neurodegeneration. Mech Ageing Dev 2013; 134:440-8. [PMID: 23643943 PMCID: PMC3834072 DOI: 10.1016/j.mad.2013.04.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Revised: 04/17/2013] [Accepted: 04/17/2013] [Indexed: 12/30/2022]
Abstract
The repair of damaged DNA is essential to maintain longevity of an organism. The brain is a matrix of different neural cell types including proliferative astrocytes and post-mitotic neurons. Post-mitotic DNA repair is a version of proliferative DNA repair, with a reduced number of available pathways and most of these attenuated. Base excision repair (BER) is one pathway that remains robust in neurons; it is this pathway that resolves the damage due to oxidative stress. This oxidative damage is an unavoidable byproduct of respiration, and considering the high metabolic activity of neurons this type of damage is particularly pertinent in the brain. The accumulation of oxidative DNA damage over time is a central aspect of the theory of aging and repair of such chronic damage is of the highest importance. We review research conducted in BER mouse models to clarify the role of this pathway in the neural system. The requirement for BER in proliferating cells also correlates with high levels of many of the BER enzymes in neurogenesis after DNA damage. However, the pathway is also necessary for normal neural maintenance as larger infarct volumes after ischemic stroke are seen in some glycosylase deficient animals. Further, the requirement for DNA polymerase β in post-mitotic BER is potentially more important than in proliferating cells due to reduced levels of replicative polymerases. The BER response may have particular relevance for the onset and progression of many neurodegenerative diseases associated with an increase in oxidative stress including Alzheimer's.
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Affiliation(s)
- Peter Sykora
- Laboratory of Molecular Gerontology, National Institute on Aging Intramural Research Program, 251 Bayview Boulevard, Suite 100, Baltimore, MD 21224, United States
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Ibáñez C, Simó C, Barupal DK, Fiehn O, Kivipelto M, Cedazo-Mínguez A, Cifuentes A. A new metabolomic workflow for early detection of Alzheimer's disease. J Chromatogr A 2013; 1302:65-71. [DOI: 10.1016/j.chroma.2013.06.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 06/05/2013] [Accepted: 06/07/2013] [Indexed: 11/16/2022]
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20
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The protein p17 signaling pathways in cancer. Tumour Biol 2013; 34:4081-7. [PMID: 23900679 DOI: 10.1007/s13277-013-0999-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 07/02/2013] [Indexed: 10/26/2022] Open
Abstract
P17 is a novel neuronal protein expressed under physiological conditions only at very low levels in other tissues. Accumulating data indicate its crucial involvement in tumorigenic effects. Using molecular, cellular, and biocomputational methods, the current study unraveled p17 mode of action. Data indicate that mitochondria-associated p17 interacts with the proteins TMEM115, YPEL3, ERP44, CDK5RAP, and NNAT. Moreover, p17 drives the cell cycle into the G0/G1 phase and enhances survival of proliferating cells. Interference with p17 activities thus might become a novel option to influence also the tumor suppressor protein p53 signaling pathways for the treatment of tumors.
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Abstract
Base excision repair (BER) corrects DNA damage from oxidation, deamination and alkylation. Such base lesions cause little distortion to the DNA helix structure. BER is initiated by a DNA glycosylase that recognizes and removes the damaged base, leaving an abasic site that is further processed by short-patch repair or long-patch repair that largely uses different proteins to complete BER. At least 11 distinct mammalian DNA glycosylases are known, each recognizing a few related lesions, frequently with some overlap in specificities. Impressively, the damaged bases are rapidly identified in a vast excess of normal bases, without a supply of energy. BER protects against cancer, aging, and neurodegeneration and takes place both in nuclei and mitochondria. More recently, an important role of uracil-DNA glycosylase UNG2 in adaptive immunity was revealed. Furthermore, other DNA glycosylases may have important roles in epigenetics, thus expanding the repertoire of BER proteins.
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Affiliation(s)
- Hans E Krokan
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, N-7489 Trondheim, Norway.
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22
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Su YH, Lee YL, Chen SF, Lee YP, Hsieh YH, Tsai JH, Hsu JL, Tian WT, Huang W. Essential role of β-human 8-oxoguanine DNA glycosylase 1 in mitochondrial oxidative DNA repair. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2013; 54:54-64. [PMID: 23055259 DOI: 10.1002/em.21742] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Accepted: 08/30/2012] [Indexed: 06/01/2023]
Abstract
8-Oxoguanine (8-OG) is the major mutagenic base lesion in DNA caused by reactive oxygen species (ROS) and accumulates in both nuclear and mitochondrial DNA (mtDNA). In humans, 8-OG is primarily removed by human 8-OG DNA glycosylase 1 (hOGG1) through the base excision repair (BER) pathway. There are two major hOGG1 isoforms, designated α- and β-hOGG1, generated by alternative splicing, and they have distinct subcellular localization: cell nuclei and mitochondria, respectively. Using yeast two-hybrid screening assays, we found that β- but not α-hOGG1 directly interacts with the mitochondrial protein NADH:ubiquinone oxidoreductase 1 beta subcomplex 10 (NDUFB10), an integral factor in Complex 1 on the mitochondrial inner membrane. Using coimmunoprecipitation and immunofluorescence studies, we found that this interaction was greatly increased by hydrogen peroxide-induced oxidative stress, suggesting that β- but not α-hOGG1 is localized in the mitochondrial inner membrane. Analyses of nuclear and mtDNA damage showed that the β- but not α- hogg1 knockdown (KD) cells were severely defective in mitochondrial BER, indicating an essential requirement of β-hOGG1 for mtDNA repair. β-hogg1 KD cells were also found to be mildly deficient in Complex I activity, suggesting that β-hOGG1 is an accessory factor for the mitochondrial integral function for ATP synthesis. In summary, our findings define β-hOGG1 as an important factor for mitochondrial BER and as an accessory factor in the mitochondrial Complex I function.
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Affiliation(s)
- Yu-Hung Su
- Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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Abstract
The pathogenesis of age-related macular degeneration (AMD) is complex and involves interactions between environmental and genetic factors, with oxidative stress playing an important role inducing damage in biomolecules, including DNA. Therefore, genetic variability in the components of DNA repair systems may influence the ability of the cell to cope with oxidative stress and in this way contribute to the pathogenesis of AMD. However, few reports have been published on this subject so far. We demonstrated that the c.977C>G polymorphism (rs1052133) in the hOGG1 gene and the c.972G>C polymorphism (rs3219489) in the MUTYH gene, the products of which play important roles in the repair of oxidatively damaged DNA, might be associated with the risk of AMD. Oxidative stress may promote misincorporation of uracil into DNA, where it is targeted by several DNA glycosylases. We observed that the g.4235T>C (rs2337395) and c.–32A>G (rs3087404) polymorphisms in two genes encoding such glycosylases, UNG and SMUG1, respectively, could be associated with the occurrence of AMD. Polymorphisms in some other DNA repair genes, including XPD (ERCC2), XRCC1 and ERCC6 (CSB) have also been reported to be associated with AMD. These data confirm the importance of the cellular reaction to DNA damage, and this may be influenced by variability in DNA repair genes, in AMD pathogenesis.
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Trypanosomes lacking uracil-DNA glycosylase are hypersensitive to antifolates and present a mutator phenotype. Int J Biochem Cell Biol 2012; 44:1555-68. [PMID: 22728162 DOI: 10.1016/j.biocel.2012.06.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Revised: 06/04/2012] [Accepted: 06/12/2012] [Indexed: 01/13/2023]
Abstract
Cells contain low amounts of uracil in DNA which can be the result of dUTP misincorporation during replication or cytosine deamination. Elimination of uracil in the base excision repair pathway yields an abasic site, which is potentially mutagenic unless repaired. The Trypanosoma brucei genome presents a single uracil-DNA glycosylase responsible for removal of uracil from DNA. Here we establish that no excision activity is detected on U:G, U:A pairs or single-strand uracil-containing DNA in uracil-DNA glycosylase null mutant cell extracts, indicating the absence of back-up uracil excision activities. While procyclic forms can survive with moderate amounts of uracil in DNA, an analysis of the mutation rate and spectra in mutant cells revealed a hypermutator phenotype where the predominant events were GC to AT transitions and insertions. Defective elimination of uracil via the base excision repair pathway gives rise to hypersensitivity to antifolates and oxidative stress and an increased number of DNA strand breaks, suggesting the activation of alternative DNA repair pathways. Finally, we show that uracil-DNA glycosylase defective cells exhibit reduced infectivity in vivo demonstrating that efficient uracil elimination is important for survival within the mammalian host.
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Choi DH, Cristóvão AC, Guhathakurta S, Lee J, Joh TH, Beal MF, Kim YS. NADPH oxidase 1-mediated oxidative stress leads to dopamine neuron death in Parkinson's disease. Antioxid Redox Signal 2012; 16:1033-45. [PMID: 22098189 PMCID: PMC3315177 DOI: 10.1089/ars.2011.3960] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
AIM Oxidative stress has long been considered as a major contributing factor in the pathogenesis of Parkinson's disease. However, molecular sources for reactive oxygen species in Parkinson's disease have not been clearly elucidated. Herein, we sought to investigate whether a superoxide-producing NADPH oxidases (NOXs) are implicated in oxidative stress-mediated dopaminergic neuronal degeneration. RESULTS Expression of various Nox isoforms and cytoplasmic components were investigated in N27, rat dopaminergic cells. While most of Nox isoforms were constitutively expressed, Nox1 expression was significantly increased after treatment with 6-hydroxydopamine. Rac1, a key regulator in the Nox1 system, was also activated. Striatal injection of 6-hydroxydopamine increased Nox1 expression in dopaminergic neurons in the rat substantia nigra. Interestingly, it was localized into the nucleus, and immunostaining for DNA oxidative stress marker, 8-oxo-dG, was increased. Nox1 expression was also found in the nucleus of dopaminergic neurons in the substantia nigra of Parkinson's disease patients. Adeno-associated virus-mediated Nox1 knockdown or Rac1 inhibition reduced 6-hydroxydopamine-induced oxidative DNA damage and dopaminergic neuronal degeneration significantly. INNOVATION Nox1/Rac1 could serve as a potential therapeutic target for Parkinson's disease. CONCLUSION We provide evidence that dopaminergic neurons are equipped with the Nox1/Rac1 superoxide-generating system. Stress-induced Nox1/Rac1 activation causes oxidative DNA damage and neurodegeneration. Reduced dopaminergic neuronal death achieved by targeting Nox1/Rac1, emphasizes the impact of oxidative stress caused by this system on the pathogenesis and therapy in Parkinson's disease.
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Affiliation(s)
- Dong-Hee Choi
- Neurology/Neuroscience Department, Weill Medical College of Cornell University, New York, New York, USA
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26
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Swartzlander DB, Bauer NC, Corbett AH, Doetsch PW. Regulation of base excision repair in eukaryotes by dynamic localization strategies. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 110:93-121. [PMID: 22749144 DOI: 10.1016/b978-0-12-387665-2.00005-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
This chapter discusses base excision repair (BER) and the known mechanisms defined thus far regulating BER in eukaryotes. Unlike the situation with nucleotide excision repair and double-strand break repair, little is known about how BER is regulated to allow for efficient and accurate repair of many types of DNA base damage in both nuclear and mitochondrial genomes. Regulation of BER has been proposed to occur at multiple, different levels including transcription, posttranslational modification, protein-protein interactions, and protein localization; however, none of these regulatory mechanisms characterized thus far affect a large spectrum of BER proteins. This chapter discusses a recently discovered mode of BER regulation defined in budding yeast cells that involves mobilization of DNA repair proteins to DNA-containing organelles in response to genotoxic stress.
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Affiliation(s)
- Daniel B Swartzlander
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
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Abstract
Mitochondria control essential cellular activities including generation of ATP via oxidative phosphorylation. Mitochondrial DNA (mtDNA) mutations in the regulatory D-loop region and somatic mtDNA mutations are common in primary human cancers. The biological impact of a given mutation may vary, depending on the nature of the mutation and the proportion of mutant mtDNAs carried by the cell. Identification of mtDNA mutations in precancerous lesions supports their early contribution to cell transformation and cancer progression. Introduction of mtDNA mutations in transformed cells has been associated with increased ROS production and tumor growth. Studies reveal that increased and altered mtDNA plays a role in the development of cancer but further work is required to establish the functional significance of specific mitochondrial mutations in cancer and disease progression. This review offers some insight into the extent of mtDNA mutations, their functional consequences in tumorigenesis, mitochondrial therapeutics, and future clinical application.
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Affiliation(s)
- Aditi Chatterjee
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, USA
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DNA repair in organelles: Pathways, organization, regulation, relevance in disease and aging. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:186-200. [DOI: 10.1016/j.bbamcr.2010.10.002] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 10/01/2010] [Accepted: 10/05/2010] [Indexed: 12/20/2022]
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Aamann MD, Sorensen MM, Hvitby C, Berquist BR, Muftuoglu M, Tian J, de Souza-Pinto NC, Scheibye-Knudsen M, Wilson DM, Stevnsner T, Bohr VA. Cockayne syndrome group B protein promotes mitochondrial DNA stability by supporting the DNA repair association with the mitochondrial membrane. FASEB J 2010; 24:2334-46. [PMID: 20181933 DOI: 10.1096/fj.09-147991] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cockayne syndrome (CS) is a human premature aging disorder associated with severe developmental deficiencies and neurodegeneration, and phenotypically it resembles some mitochondrial DNA (mtDNA) diseases. Most patients belong to complementation group B, and the CS group B (CSB) protein plays a role in genomic maintenance and transcriptome regulation. By immunocytochemistry, mitochondrial fractionation, and Western blotting, we demonstrate that CSB localizes to mitochondria in different types of cells, with increased mitochondrial distribution following menadione-induced oxidative stress. Moreover, our results suggest that CSB plays a significant role in mitochondrial base excision repair (BER) regulation. In particular, we find reduced 8-oxo-guanine, uracil, and 5-hydroxy-uracil BER incision activities in CSB-deficient cells compared to wild-type cells. This deficiency correlates with deficient association of the BER activities with the mitochondrial inner membrane, suggesting that CSB may participate in the anchoring of the DNA repair complex. Increased mutation frequency in mtDNA of CSB-deficient cells demonstrates functional significance of the presence of CSB in the mitochondria. The results in total suggest that CSB plays a direct role in mitochondrial BER by helping recruit, stabilize, and/or retain BER proteins in repair complexes associated with the inner mitochondrial membrane, perhaps providing a novel basis for understanding the complex phenotype of this debilitating disorder.
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Affiliation(s)
- Maria D Aamann
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, 5600 Nathan Shock Dr., Baltimore, MD 21224, USA
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Gredilla R, Bohr VA, Stevnsner T. Mitochondrial DNA repair and association with aging--an update. Exp Gerontol 2010; 45:478-88. [PMID: 20096766 DOI: 10.1016/j.exger.2010.01.017] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 01/10/2010] [Accepted: 01/14/2010] [Indexed: 01/07/2023]
Abstract
Mitochondrial DNA is constantly exposed to oxidative injury. Due to its location close to the main site of reactive oxygen species, the inner mitochondrial membrane, mtDNA is more susceptible than nuclear DNA to oxidative damage. The accumulation of DNA damage is thought to play a critical role in the aging process and to be particularly deleterious in post-mitotic cells. Thus, DNA repair is an important mechanism for maintenance of genomic integrity. Despite the importance of mitochondria in the aging process, it was thought for many years that mitochondria lacked an enzymatic DNA repair system comparable to that in the nuclear compartment. However, it is now well established that DNA repair actively takes place in mitochondria. Oxidative DNA damage processing, base excision repair mechanisms were the first to be described in these organelles, and consequently the best understood. However, new proteins and novel DNA repair pathways, thought to be exclusively present in the nucleus, have recently been described also to be present in mitochondria. Here we review the main mitochondrial DNA repair pathways and their association with the aging process.
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Affiliation(s)
- Ricardo Gredilla
- Danish Center for Molecular Gerontology, Department of Molecular Biology, Aarhus University, C.F. Moellers allé 3, Aarhus C, Denmark
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Boesch P, Ibrahim N, Dietrich A, Lightowlers RN. Membrane association of mitochondrial DNA facilitates base excision repair in mammalian mitochondria. Nucleic Acids Res 2009; 38:1478-88. [PMID: 20007607 PMCID: PMC2836570 DOI: 10.1093/nar/gkp1143] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Mitochondrial DNA encodes a set of 13 polypeptides and is subjected to constant oxidative stress due to ROS production within the organelle. It has been shown that DNA repair in the mitochondrion proceeds through both short- and long-patch base excision repair (BER). In the present article, we have used the natural competence of mammalian mitochondria to import DNA and study the sub-mitochondrial localization of the repair system in organello. Results demonstrate that sequences corresponding to the mtDNA non-coding region interact with the inner membrane in a rapid and saturable fashion. We show that uracil containing import substrates are taken into the mitochondrion and are used as templates for damage driven DNA synthesis. After further sub-fractionation, we show that the length of the repair synthesis patch differs in the soluble and the particulate fraction. Bona fide long patch BER synthesis occurs on the DNA associated with the particulate fraction, whereas a nick driven DNA synthesis occurs when the uracil containing DNA accesses the soluble fraction. Our results suggest that coordinate interactions of the different partners needed for BER is only found at sites where the DNA is associated with the membrane.
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Affiliation(s)
- Pierre Boesch
- Mitochondrial Research Group, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
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Pulukuri SMK, Knost JA, Estes N, Rao JS. Small interfering RNA-directed knockdown of uracil DNA glycosylase induces apoptosis and sensitizes human prostate cancer cells to genotoxic stress. Mol Cancer Res 2009; 7:1285-93. [PMID: 19671688 DOI: 10.1158/1541-7786.mcr-08-0508] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Uracil DNA glycosylase (UNG) is the primary enzyme responsible for removing uracil residues from DNA. Although a substantial body of evidence suggests that DNA damage plays a role in cancer cell apoptosis, the underlying mechanisms are poorly understood. In particular, very little is known about the role of base excision repair of misincorporated uracil in cell survival. To test the hypothesis that the repair of DNA damage associated with uracil misincorporation is critical for cancer cell survival, we used small interfering RNA (siRNA) to target the human UNG gene. In a dose-dependent and time-dependent manner, siRNA specifically inhibited UNG expression and modified the expression of several genes at both mRNA and protein levels. In LNCaP cells, p53, p21, and Bax protein levels increased, whereas Bcl2 levels decreased. In DU145 cells, p21 levels were elevated, although mutant p53 and Bax levels remained unchanged. In PC3 cells, UNG inhibition resulted in elevated p21 and Bax levels. In all three cell lines, UNG inhibition reduced cell proliferation, induced apoptosis, and increased cellular sensitivity to genotoxic stress. Furthermore, an in vitro cleavage experiment using uracil-containing double-stranded DNA as a template has shown that siRNA-mediated knockdown of UNG expression significantly reduced the uracil-excising activity of UNG in human prostate cancer cells, which was associated with DNA damage analyzed by comet assay. Taken together, these findings indicate that RNA interference-directed targeting of UNG is a convenient, novel tool for studying the biological role of UNG and raises the potential of its application for prostate cancer therapy.
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Affiliation(s)
- Sai Murali Krishna Pulukuri
- Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine, Peoria, IL 61605, USA
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Boesch P, Ibrahim N, Paulus F, Cosset A, Tarasenko V, Dietrich A. Plant mitochondria possess a short-patch base excision DNA repair pathway. Nucleic Acids Res 2009; 37:5690-700. [PMID: 19625491 PMCID: PMC2761273 DOI: 10.1093/nar/gkp606] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Despite constant threat of oxidative damage, sequence drift in mitochondrial and chloroplast DNA usually remains very low in plant species, indicating efficient defense and repair. Whereas the antioxidative defense in the different subcellular compartments is known, the information on DNA repair in plant organelles is still scarce. Focusing on the occurrence of uracil in the DNA, the present work demonstrates that plant mitochondria possess a base excision repair (BER) pathway. In vitro and in organello incision assays of double-stranded oligodeoxyribonucleotides showed that mitochondria isolated from plant cells contain DNA glycosylase activity specific for uracil cleavage. A major proportion of the uracil–DNA glycosylase (UDG) was associated with the membranes, in agreement with the current hypothesis that the DNA is replicated, proofread and repaired in inner membrane-bound nucleoids. Full repair, from uracil excision to thymidine insertion and religation, was obtained in organello following import of a uracil-containing DNA fragment into isolated plant mitochondria. Repair occurred through single nucleotide insertion, which points to short-patch BER. In vivo targeting and in vitro import of GFP fusions showed that the putative UDG encoded by the At3g18 630 locus might be the first enzyme of this mitochondrial pathway in Arabidopsis thaliana.
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Affiliation(s)
- Pierre Boesch
- Institut de Biologie Moléculaire des Plantes, CNRS and Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France
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Rothfuss O, Fischer H, Hasegawa T, Maisel M, Leitner P, Miesel F, Sharma M, Bornemann A, Berg D, Gasser T, Patenge N. Parkin protects mitochondrial genome integrity and supports mitochondrial DNA repair. Hum Mol Genet 2009; 18:3832-50. [PMID: 19617636 DOI: 10.1093/hmg/ddp327] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mutations in the parkin gene are the most common cause of recessive familial Parkinson disease (PD). Parkin has been initially characterized as an ubiquitin E3 ligase, but the pathological relevance of this activity remains uncertain. Recently, an impressive amount of evidence has accumulated that parkin is involved in the maintenance of mitochondrial function and biogenesis. We used a human neuroblastoma cell line as a model to study the influence of endogenous parkin on mitochondrial genomic integrity. Using an unbiased chromatin immunoprecipitation approach, we found that parkin is associated physically with mitochondrial DNA (mtDNA) in proliferating as well as in differentiated SH-SY5Y cells. In vivo, the association of parkin with mtDNA could be confirmed in brain tissue of mouse and human origin. Replication and transcription of mtDNA were enhanced in SH-SY5Y cells over-expressing the parkin gene. The ability of parkin to support mtDNA-metabolism was impaired by pathogenic parkin point mutations. Most importantly, we show that parkin protects mtDNA from oxidative damage and stimulates mtDNA repair. Moreover, higher susceptibility of mtDNA to reactive oxygen species and reduced mtDNA repair capacity was observed in parkin-deleted fibroblasts of a PD patient. Our data indicate a novel role for parkin in directly supporting mitochondrial function and protecting mitochondrial genomic integrity from oxidative stress.
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Affiliation(s)
- Oliver Rothfuss
- Department for Neurodegenerative Diseases, Center of Neurology and Hertie Institute for Clinical Brain Research, University of Tübingen, Germany
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Yonekura SI, Nakamura N, Yonei S, Zhang-Akiyama QM. Generation, biological consequences and repair mechanisms of cytosine deamination in DNA. JOURNAL OF RADIATION RESEARCH 2009; 50:19-26. [PMID: 18987436 DOI: 10.1269/jrr.08080] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Base moieties in DNA are spontaneously threatened by naturally occurring chemical reactions such as deamination, hydrolysis and oxidation. These DNA modifications have been considered to be major causes of cell death, mutations and cancer induction in organisms. Organisms have developed the DNA base excision repair pathway as a defense mechanism to protect them from these threats. DNA glycosylases, the key enzyme in the base excision repair pathway, are highly conserved in evolution. Uracil constantly occurs in DNA. Uracil in DNA arises by spontaneous deamination of cytosine to generate pro-mutagenic U:G mispairs. Uracil in DNA is also produced by the incorporation of dUMP during DNA replication. Uracil-DNA glycosylase (UNG) acts as a major repair enzyme that protects DNA from the deleterious consequences of uracil. The first UNG activity was discovered in E. coli in 1974. This was also the first discovery of base excision repair. The sequence encoded by the ung gene demonstrates that the E. coli UNG is highly conserved in viruses, bacteria, archaea, yeast, mice and humans. In this review, we will focus on central and recent findings on the generation, biological consequences and repair mechanisms of uracil in DNA and on the biological significance of uracil-DNA glycosylase.
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Affiliation(s)
- Shin-Ichiro Yonekura
- Department of Biological Sciences, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
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Visnes T, Akbari M, Hagen L, Slupphaug G, Krokan HE. The rate of base excision repair of uracil is controlled by the initiating glycosylase. DNA Repair (Amst) 2008; 7:1869-81. [PMID: 18721906 DOI: 10.1016/j.dnarep.2008.07.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 07/17/2008] [Accepted: 07/21/2008] [Indexed: 11/16/2022]
Abstract
Uracil in DNA is repaired by base excision repair (BER) initiated by a DNA glycosylase, followed by strand incision, trimming of ends, gap filling and ligation. Uracil in DNA comes in two distinct forms; U:A pairs, typically resulting from replication errors, and mutagenic U:G mismatches, arising from cytosine deamination. To identify proteins critical to the rate of repair of these lesions, we quantified overall repair of U:A pairs, U:G mismatches and repair intermediates (abasic sites and nicked abasic sites) in vitro. For this purpose we used circular DNA substrates and nuclear extracts of eight human cell lines with wide variation in the content of BER proteins. We identified the initiating uracil-DNA glycosylase UNG2 as the major overall rate-limiting factor. UNG2 is apparently the sole glycosylase initiating BER of U:A pairs and generally initiated repair of almost 90% of the U:G mismatches. Surprisingly, TDG contributed at least as much as single-strand selective monofunctional uracil-DNA glycosylase 1 (SMUG1) to BER of U:G mismatches. Furthermore, in a cell line that expressed unusually high amounts of TDG, this glycosylase contributed to initiation of as much as approximately 30% of U:G repair. Repair of U:G mismatches was generally faster than that of U:A pairs, which agrees with the known substrate preference of UNG-type glycosylases. Unexpectedly, repair of abasic sites opposite G was also generally faster than when opposite A, and this could not be explained by the properties of the purified APE1 protein. It may rather reflect differences in substrate recognition or repair by different complex(es). Lig III is apparently a minor rate-regulator for U:G repair. APE1, Pol beta, Pol delta, PCNA, XRCC1 and Lig I did not seem to be rate-limiting for overall repair of any of the substrates. These results identify damaged base removal as the major rate-limiting step in BER of uracil in human cells.
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Affiliation(s)
- Torkild Visnes
- Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, Erling Skjalgssons gate 1, Trondheim, Norway
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Microarray based analysis of temperature and oxidative stress induced messenger RNA in Schistosoma mansoni. Mol Biochem Parasitol 2008; 162:134-41. [PMID: 18775750 DOI: 10.1016/j.molbiopara.2008.08.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Revised: 08/10/2008] [Accepted: 08/11/2008] [Indexed: 01/06/2023]
Abstract
The body's defense against schistosome infection can take many forms. For example, upon developing acute schistosomiasis, patients often have fever coinciding with larval maturation, migration and early oviposition. As the infection becomes established, the parasite comes under oxidative stress generated by the host immune system. The most common treatment for schistosomiasis is the anti-helminthic drug praziquantel. Its effectiveness, however, is limited due to its inability to kill schistosomes 2-4 weeks post-infection. Clearly there is a need for new anti-schistosomal drugs. We hypothesize that gene products expressed as part of a protective response against heat and/or oxidative stress are potential therapeutic targets for future drug development. Using a 12,166 element oligonucleotide microarray to characterize Schistosoma mansoni genes induced by heat and oxidative stress we found that 1878 S. mansoni elements were significantly induced by heat stress. These included previously reported heat-shock genes expressing homologs of HSP40, HSP70 and HSP86. One thousand and one elements were induced by oxidative stress including those expressing homologs of superoxide dismutase, glutathione peroxidase and aldehyde dehydrogenase. Seventy-two elements were common to both stressors and could potentially be exploited in the development of novel anti-schistosomal therapeutics.
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Westbye MP, Feyzi E, Aas PA, Vågbø CB, Talstad VA, Kavli B, Hagen L, Sundheim O, Akbari M, Liabakk NB, Slupphaug G, Otterlei M, Krokan HE. Human AlkB homolog 1 is a mitochondrial protein that demethylates 3-methylcytosine in DNA and RNA. J Biol Chem 2008; 283:25046-56. [PMID: 18603530 DOI: 10.1074/jbc.m803776200] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Escherichia coli AlkB protein and human homologs hABH2 and hABH3 are 2-oxoglutarate (2OG)/Fe(II)-dependent DNA/RNA demethylases that repair 1-methyladenine and 3-methylcytosine residues. Surprisingly, hABH1, which displays the strongest homology to AlkB, failed to show repair activity in two independent studies. Here, we show that hABH1 is a mitochondrial protein, as demonstrated using fluorescent fusion protein expression, immunocytochemistry, and Western blot analysis. A fraction is apparently nuclear and this fraction increases strongly if the fluorescent tag is placed at the N-terminal end of the protein, thus interfering with mitochondrial targeting. Molecular modeling of hABH1 based upon the sequence and known structures of AlkB and hABH3 suggested an active site almost identical to these enzymes. hABH1 decarboxylates 2OG in the absence of a prime substrate, and the activity is stimulated by methylated nucleotides. Employing three different methods we demonstrate that hABH1 demethylates 3-methylcytosine in single-stranded DNA and RNA in vitro. Site-specific mutagenesis confirmed that the putative Fe(II) and 2OG binding residues are essential for activity. In conclusion, hABH1 is a functional mitochondrial AlkB homolog that repairs 3-methylcytosine in single-stranded DNA and RNA.
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Affiliation(s)
- Marianne Pedersen Westbye
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, N-7489 Trondheim, Norway
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Abstract
DNA damage is a form of cell stress and injury that has been implicated in the pathogenesis of many neurologic disorders, including amyotrophic lateral sclerosis, Alzheimer disease, Down syndrome, Parkinson disease, cerebral ischemia, and head trauma. However, most data reveal only associations, and the role for DNA damage in direct mechanisms of neurodegeneration is vague with respect to being a definitive upstream cause of neuron cell death, rather than a consequence of the degeneration. Although neurons seem inclined to develop DNA damage during oxidative stress, most of the existing work on DNA damage and repair mechanisms has been done in the context of cancer biology using cycling nonneuronal cells but not nondividing (i.e. postmitotic) neurons. Nevertheless, the identification of mutations in genes that encode proteins that function in DNA repair and DNA damage response in human hereditary DNA repair deficiency syndromes and ataxic disorders is establishing a mechanistic precedent that clearly links DNA damage and DNA repair abnormalities with progressive neurodegeneration. This review summarizes DNA damage and repair mechanisms and their potential relevance to the evolution of degeneration in postmitotic neurons.
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Affiliation(s)
- Lee J Martin
- Department of Pathology, Division of Neuropathology, and Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2196, USA.
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40
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Akbari M, Visnes T, Krokan HE, Otterlei M. Mitochondrial base excision repair of uracil and AP sites takes place by single-nucleotide insertion and long-patch DNA synthesis. DNA Repair (Amst) 2008; 7:605-16. [PMID: 18295553 DOI: 10.1016/j.dnarep.2008.01.002] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2007] [Revised: 01/04/2008] [Accepted: 01/04/2008] [Indexed: 01/28/2023]
Abstract
Base excision repair (BER) corrects a variety of small base lesions in DNA. The UNG gene encodes both the nuclear (UNG2) and the mitochondrial (UNG1) forms of the human uracil-DNA glycosylase (UDG). We prepared mitochondrial extracts free of nuclear BER proteins from human cell lines. Using these extracts we show that UNG is the only detectable UDG in mitochondria, and mitochondrial BER (mtBER) of uracil and AP sites occur by both single-nucleotide insertion and long-patch repair DNA synthesis. Importantly, extracts of mitochondria carry out repair of modified AP sites which in nuclei occurs through long-patch BER. Such lesions may be rather prevalent in mitochondrial DNA because of its proximity to the electron transport chain, the primary site of production of reactive oxygen species. Furthermore, mitochondrial extracts remove 5' protruding flaps from DNA which can be formed during long-patch BER, by a "flap endonuclease like" activity, although flap endonuclease (FEN1) is not present in mitochondria. In conclusion, combined short- and long-patch BER activities enable mitochondria to repair a broader range of lesions in mtDNA than previously known.
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Affiliation(s)
- Mansour Akbari
- Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, N-7006 Trondheim, Norway
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Setzer B, Lebrecht D, Walker UA. Pyrimidine nucleoside depletion sensitizes to the mitochondrial hepatotoxicity of the reverse transcriptase inhibitor stavudine. THE AMERICAN JOURNAL OF PATHOLOGY 2008; 172:681-90. [PMID: 18276780 DOI: 10.2353/ajpath.2008.070613] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Stavudine is a hepatotoxic antiretroviral nucleoside analogue that also inhibits the replication of mitochondrial DNA (mtDNA). To elucidate the mechanism and consequences of mtDNA depletion, we treated HepG2 cells with stavudine and either redoxal, an inhibitor of de novo pyrimidine synthesis, or uridine, from which pyrimidine pools are salvaged. Compared with treatment with stavudine alone, co-treatment with redoxal accelerated mtDNA depletion, impaired cell division, and activated caspase 3. These adverse effects were completely abrogated by uridine. Intracellular ATP levels were unaffected. Transcriptosome profiling demonstrated that redoxal and stavudine acted synergistically to induce CDKN2A and p21, indicating cell cycle arrest in G1, as well as genes involved in intrinsic and extrinsic apoptosis. Moreover, redoxal and stavudine showed synergistic interaction in the up-regulation of transcripts encoded by mtDNA and the induction of nuclear transcripts participating in energy metabolism, mitochondrial biogenesis, oxidative stress, and DNA repair. Genes involved in nucleotide metabolism were also synergistically up-regulated by both agents; this effect was completely antagonized by uridine. Thus, pyrimidine depletion sensitizes cells to stavudine-mediated mtDNA depletion and enhances secondary cell toxicity. Our results indicate that drugs that diminish pyrimidine pools should be avoided in stavudine-treated human immunodeficiency virus patients. Uridine supplementation reverses this toxicity and, because of its good tolerability, has potential clinical value for the treatment of side effects associated with pyrimidine depletion.
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Affiliation(s)
- Bernhard Setzer
- Department of Rheumatology and Clinical Immunology,Medizinische Universitätsklinik, Hugstetterstr. 55, D-79106 Freiburg, Germany
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Akbari M, Krokan HE. Cytotoxicity and mutagenicity of endogenous DNA base lesions as potential cause of human aging. Mech Ageing Dev 2008; 129:353-65. [PMID: 18355895 DOI: 10.1016/j.mad.2008.01.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 01/25/2008] [Accepted: 01/28/2008] [Indexed: 11/26/2022]
Abstract
Endogenous factors constitute a substantial source of damage to the genomic DNA. The type of damage includes a number of different base lesions and single- and double-strand breaks. Unrepaired DNA damage can give rise to mutations and may cause cell death. A number of studies have demonstrated an association between aging and the accumulation of DNA damage. This may be attributed to reduced DNA repair with age, although this is apparently not a general feature for all types of damage and repair mechanisms. Therefore, detailed studies that improve our knowledge of DNA repair systems as well as mutagenic and toxic effects of DNA lesions will help us to gain a better insight into the mechanisms of aging. The aim of this review is to provide a brief description of cytotoxic and mutagenic endogenous DNA lesions that are mainly repaired by base excision repair and single-strand break repair pathways and to discuss the potential role of DNA lesions and DNA repair dysfunction in the onset of human aging.
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Affiliation(s)
- Mansour Akbari
- Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
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Guikema JEJ, Linehan EK, Tsuchimoto D, Nakabeppu Y, Strauss PR, Stavnezer J, Schrader CE. APE1- and APE2-dependent DNA breaks in immunoglobulin class switch recombination. ACTA ACUST UNITED AC 2007; 204:3017-26. [PMID: 18025127 PMCID: PMC2118529 DOI: 10.1084/jem.20071289] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Antibody class switch recombination (CSR) occurs by an intrachromosomal deletion requiring generation of double-stranded breaks (DSBs) in switch-region DNA. The initial steps in DSB formation have been elucidated, involving cytosine deamination by activation-induced cytidine deaminase and generation of abasic sites by uracil DNA glycosylase. However, it is not known how abasic sites are converted into single-stranded breaks and, subsequently, DSBs. Apurinic/apyrimidinic endonuclease (APE) efficiently nicks DNA at abasic sites, but it is unknown whether APE participates in CSR. We address the roles of the two major mammalian APEs, APE1 and APE2, in CSR. APE1 deficiency causes embryonic lethality in mice; we therefore examined CSR and DSBs in mice deficient in APE2 and haploinsufficient for APE1. We show that both APE1 and APE2 function in CSR, resulting in the DSBs necessary for CSR and thereby describing a novel in vivo function for APE2.
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Affiliation(s)
- Jeroen E J Guikema
- Department of Molecular Genetics and Microbiology, Program in Immunology and Virology, University of Massachusetts Medical School, Worcester, MA 01655, USA
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