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Kretschmer S, Wolf C, König N, Staroske W, Guck J, Häusler M, Luksch H, Nguyen LA, Kim B, Alexopoulou D, Dahl A, Rapp A, Cardoso MC, Shevchenko A, Lee-Kirsch MA. SAMHD1 prevents autoimmunity by maintaining genome stability. Ann Rheum Dis 2015; 74:e17. [PMID: 24445253 PMCID: PMC4345975 DOI: 10.1136/annrheumdis-2013-204845] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 12/31/2013] [Accepted: 01/02/2014] [Indexed: 11/10/2022]
Abstract
OBJECTIVES The HIV restriction factor, SAMHD1 (SAM domain and HD domain-containing protein 1), is a triphosphohydrolase that degrades deoxyribonucleoside triphosphates (dNTPs). Mutations in SAMHD1 cause Aicardi-Goutières syndrome (AGS), an inflammatory disorder that shares phenotypic similarity with systemic lupus erythematosus, including activation of antiviral type 1 interferon (IFN). To further define the pathomechanisms underlying autoimmunity in AGS due to SAMHD1 mutations, we investigated the physiological properties of SAMHD1. METHODS Primary patient fibroblasts were examined for dNTP levels, proliferation, senescence, cell cycle progression and DNA damage. Genome-wide transcriptional profiles were generated by RNA sequencing. Interaction of SAMHD1 with cyclin A was assessed by coimmunoprecipitation and fluorescence cross-correlation spectroscopy. Cell cycle-dependent phosphorylation of SAMHD1 was examined in synchronised HeLa cells and using recombinant SAMHD1. SAMHD1 was knocked down by RNA interference. RESULTS We show that increased dNTP pools due to SAMHD1 deficiency cause genome instability in fibroblasts of patients with AGS. Constitutive DNA damage signalling is associated with cell cycle delay, cellular senescence, and upregulation of IFN-stimulated genes. SAMHD1 is phosphorylated by cyclin A/cyclin-dependent kinase 1 in a cell cycle-dependent manner, and its level fluctuates during the cell cycle, with the lowest levels observed in G1/S phase. Knockdown of SAMHD1 by RNA interference recapitulates activation of DNA damage signalling and type 1 IFN activation. CONCLUSIONS SAMHD1 is required for genome integrity by maintaining balanced dNTP pools. dNTP imbalances due to SAMHD1 deficiency cause DNA damage, leading to intrinsic activation of IFN signalling. These findings establish a novel link between DNA damage signalling and innate immune activation in the pathogenesis of autoimmunity.
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Affiliation(s)
- Stefanie Kretschmer
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Christine Wolf
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Nadja König
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Wolfgang Staroske
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Jochen Guck
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK
| | - Martin Häusler
- Department of Pediatrics, University Hospital, University of Aachen, Aachen, Germany
| | - Hella Luksch
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Laura A Nguyen
- Department of Pediatrics, Center for Drug Discovery, Emory University, Atlanta, Georgia, USA
| | - Baek Kim
- Department of Pediatrics, Center for Drug Discovery, Emory University, Atlanta, Georgia, USA
- College of Pharmacy, Kyung-Hee University, Seoul, South Korea
| | - Dimitra Alexopoulou
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
- Center for Regenerative Therapies, Technische Universität Dresden, Dresden, Germany
| | - Andreas Dahl
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
- Center for Regenerative Therapies, Technische Universität Dresden, Dresden, Germany
| | - Alexander Rapp
- Department of Biology, Technische Universität Darmstadt, Germany
| | | | - Anna Shevchenko
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Min Ae Lee-Kirsch
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
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152
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Clausen AR, Lujan SA, Burkholder AB, Orebaugh CD, Williams JS, Clausen MF, Malc EP, Mieczkowski PA, Fargo DC, Smith DJ, Kunkel TA. Tracking replication enzymology in vivo by genome-wide mapping of ribonucleotide incorporation. Nat Struct Mol Biol 2015; 22:185-91. [PMID: 25622295 PMCID: PMC4351163 DOI: 10.1038/nsmb.2957] [Citation(s) in RCA: 161] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 12/18/2014] [Indexed: 12/12/2022]
Abstract
Ribonucleotides are frequently incorporated into DNA during replication in eukaryotes. Here we map genome-wide distribution of these ribonucleotides as markers of replication enzymology in budding yeast, using a new 5' DNA end-mapping method, hydrolytic end sequencing (HydEn-seq). HydEn-seq of DNA from ribonucleotide excision repair-deficient strains reveals replicase- and strand-specific patterns of ribonucleotides in the nuclear genome. These patterns support the roles of DNA polymerases α and δ in lagging-strand replication and of DNA polymerase ɛ in leading-strand replication. They identify replication origins, termination zones and variations in ribonucleotide incorporation frequency across the genome that exceed three orders of magnitude. HydEn-seq also reveals strand-specific 5' DNA ends at mitochondrial replication origins, thus suggesting unidirectional replication of a circular genome. Given the conservation of enzymes that incorporate and process ribonucleotides in DNA, HydEn-seq can be used to track replication enzymology in other organisms.
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Affiliation(s)
- Anders R Clausen
- Genome Integrity &Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institute of Health (NIH), Research Triangle Park, North Carolina, USA
| | - Scott A Lujan
- Genome Integrity &Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institute of Health (NIH), Research Triangle Park, North Carolina, USA
| | - Adam B Burkholder
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina, USA
| | - Clinton D Orebaugh
- Genome Integrity &Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institute of Health (NIH), Research Triangle Park, North Carolina, USA
| | - Jessica S Williams
- Genome Integrity &Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institute of Health (NIH), Research Triangle Park, North Carolina, USA
| | - Maryam F Clausen
- Department of Genetics, High Throughput Sequencing Facility, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Ewa P Malc
- Department of Genetics, High Throughput Sequencing Facility, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Piotr A Mieczkowski
- Department of Genetics, High Throughput Sequencing Facility, University of North Carolina, Chapel Hill, North Carolina, USA
| | - David C Fargo
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina, USA
| | - Duncan J Smith
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, USA
| | - Thomas A Kunkel
- Genome Integrity &Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institute of Health (NIH), Research Triangle Park, North Carolina, USA
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153
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Nguyen LA, Domaoal RA, Kennedy EM, Kim DH, Schinazi RF, Kim B. Pre-steady state kinetic analysis of HIV-1 reverse transcriptase for non-canonical ribonucleoside triphosphate incorporation and DNA synthesis from ribonucleoside-containing DNA template. Antiviral Res 2015; 115:75-82. [PMID: 25557601 PMCID: PMC4323949 DOI: 10.1016/j.antiviral.2014.12.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 12/15/2014] [Accepted: 12/22/2014] [Indexed: 12/12/2022]
Abstract
Non-dividing macrophages maintain extremely low cellular deoxyribonucleotide triphosphate (dNTP) levels, but high ribonucleotide triphosphate (rNTP) concentrations. The disparate nucleotide pools kinetically forces Human Immunodeficiency Virus 1 (HIV-1) reverse transcriptase (RT) to incorporate non-canonical rNTPs during reverse transcription. HIV-1 RT pauses near ribonucleoside monophosphates (rNMPs) embedded in the template DNA, which has previously been shown to enhance mismatch extension. Here, pre-steady state kinetic analysis shows rNTP binding affinity (Kd) of HIV-1 RT for non-canonical rNTPs was 1.4- to 43-fold lower, and the rNTP rate of incorporation (kpol) was 15- to 1551-fold slower than for dNTPs. This suggests that RT is more selective for incorporation of dNTPs rather than rNTPs. HIV-1 RT selectivity for dNTP versus rNTP is the lowest for ATP, implying that HIV-1 RT preferentially incorporates ATP when dATP concentration is limited. We observed that incorporation of a dNTP occurring one nucleotide before an embedded rNMP in the template had a 29-fold greater Kd and a 20-fold slower kpol as compared to the same template containing dNMP. This reduced the overall dNTP incorporation efficiency of HIV-1 RT by 581-fold. Finally, the RT mutant Y115F displayed lower discrimination against rNTPs due to its increase in binding affinity for non-canonical rNTPs. Overall, these kinetic results demonstrate that HIV-1 RT utilizes both substrate binding and a conformational change during: (1) enzymatic discrimination of non-canonical rNTPs from dNTPs and (2) during dNTP primer extension with DNA templates containing embedded rNMP.
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Affiliation(s)
- Laura A Nguyen
- Department of Pathology, University of Rochester Medical Center, Rochester, NY, USA
| | - Robert A Domaoal
- Center for Drug Discovery, Emory Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - Edward M Kennedy
- Department of Pathology, University of Rochester Medical Center, Rochester, NY, USA
| | - Dong-Hyun Kim
- College of Pharmacy, Kyung-Hee University, Seoul, South Korea
| | - Raymond F Schinazi
- Center for Drug Discovery, Emory Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA; Veterans Affairs Medical Center, Decatur, GA, USA
| | - Baek Kim
- Center for Drug Discovery, Emory Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA.
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154
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Vaisman A, Woodgate R. Redundancy in ribonucleotide excision repair: Competition, compensation, and cooperation. DNA Repair (Amst) 2015; 29:74-82. [PMID: 25753809 DOI: 10.1016/j.dnarep.2015.02.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 02/07/2015] [Accepted: 02/09/2015] [Indexed: 10/24/2022]
Abstract
The survival of all living organisms is determined by their ability to reproduce, which in turn depends on accurate duplication of chromosomal DNA. In order to ensure the integrity of genome duplication, DNA polymerases are equipped with stringent mechanisms by which they select and insert correctly paired nucleotides with a deoxyribose sugar ring. However, this process is never 100% accurate. To fix occasional mistakes, cells have evolved highly sophisticated and often redundant mechanisms. A good example is mismatch repair (MMR), which corrects the majority of mispaired bases and which has been extensively studied for many years. On the contrary, pathways leading to the replacement of nucleotides with an incorrect sugar that is embedded in chromosomal DNA have only recently attracted significant attention. This review describes progress made during the last few years in understanding such pathways in both prokaryotes and eukaryotes. Genetic studies in Escherichia coli and Saccharomyces cerevisiae demonstrated that MMR has the capacity to replace errant ribonucleotides, but only when the base is mispaired. In contrast, the major evolutionarily conserved ribonucleotide repair pathway initiated by the ribonuclease activity of type 2 Rnase H has broad specificity. In yeast, this pathway also requires the concerted action of Fen1 and pol δ, while in bacteria it can be successfully completed by DNA polymerase I. Besides these main players, all organisms contain alternative enzymes able to accomplish the same tasks, although with differing efficiency and fidelity. Studies in bacteria have very recently demonstrated that isolated rNMPs can be removed from genomic DNA by error-free nucleotide excision repair (NER), while studies in yeast suggest the involvement of topoisomerase 1 in alternative mutagenic ribonucleotide processing. This review summarizes the most recent progress in understanding the ribonucleotide repair mechanisms in prokaryotes and eukaryotes.
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Affiliation(s)
- Alexandra Vaisman
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-3371, USA
| | - Roger Woodgate
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-3371, USA.
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155
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Enzymatic Activities of RNase H Domains of HIV-1 Reverse Transcriptase with Substrate Binding Domains of Bacterial RNases H1 and H2. Mol Biotechnol 2015; 57:526-38. [DOI: 10.1007/s12033-015-9846-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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156
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Kasher PR, Jenkinson EM, Briolat V, Gent D, Morrissey C, Zeef LAH, Rice GI, Levraud JP, Crow YJ. Characterization of samhd1 morphant zebrafish recapitulates features of the human type I interferonopathy Aicardi-Goutières syndrome. THE JOURNAL OF IMMUNOLOGY 2015; 194:2819-25. [PMID: 25672750 DOI: 10.4049/jimmunol.1403157] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In humans, loss of function mutations in the SAMHD1 (AGS5) gene cause a severe form of Aicardi-Goutières syndrome (AGS), an inherited inflammatory-mediated encephalopathy characterized by increased type I IFN activity and upregulation of IFN-stimulated genes (ISGs). In particular, SAMHD1-related AGS is associated with a distinctive cerebrovascular pathology that commonly leads to stroke. Although inflammatory responses are observed in immune cells cultured from Samhd1 null mouse models, these mice are physically healthy, specifically lacking a brain phenotype. We have investigated the use of zebrafish as an alternative system for generating a clinically relevant model of SAMHD1-related AGS. Using temporal gene knockdown of zebrafish samhd1, we observe hindbrain ventricular swelling and brain hemorrhage. Furthermore, loss of samhd1 or of another AGS-associated gene, adar, leads to a significant upregulation of innate immune-related genes and an increase in the number of cells expressing the zebrafish type I IFN ifnphi1. To our knowledge, this is the first example of an in vivo model of AGS that recapitulates features of both the innate immune and neurological characteristics of the disease. The phenotypes associated with loss of samhd1 and adar suggest a function of these genes in controlling innate immune processes conserved to zebrafish, thereby also contributing to our understanding of antiviral signaling in this model organism.
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Affiliation(s)
- Paul R Kasher
- Manchester Centre for Genomic Medicine, Institute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, Manchester M13 9WL, United Kingdom;
| | - Emma M Jenkinson
- Manchester Centre for Genomic Medicine, Institute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, Manchester M13 9WL, United Kingdom
| | - Valérie Briolat
- Institut Pasteur, Macrophages et Développement de l'Immunité, F-75015 Paris, France; Centre National de la Recherche Scientifique, Unité de Recherche Associée 2578, F-75015 Paris, France
| | - David Gent
- Manchester Centre for Genomic Medicine, Institute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, Manchester M13 9WL, United Kingdom
| | - Catherine Morrissey
- Manchester Centre for Genomic Medicine, Institute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, Manchester M13 9WL, United Kingdom
| | - Leo A H Zeef
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom; and
| | - Gillian I Rice
- Manchester Centre for Genomic Medicine, Institute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, Manchester M13 9WL, United Kingdom
| | - Jean-Pierre Levraud
- Institut Pasteur, Macrophages et Développement de l'Immunité, F-75015 Paris, France; Centre National de la Recherche Scientifique, Unité de Recherche Associée 2578, F-75015 Paris, France
| | - Yanick J Crow
- Manchester Centre for Genomic Medicine, Institute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, Manchester M13 9WL, United Kingdom; Laboratory of Neurogenetics and Neuroinflammation, Imagine Institute, Necker Hospital for Sick Children, 75015 Paris, France
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157
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Type I interferonopathies: Mendelian type I interferon up-regulation. Curr Opin Immunol 2015; 32:7-12. [DOI: 10.1016/j.coi.2014.10.005] [Citation(s) in RCA: 138] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 09/19/2014] [Accepted: 10/10/2014] [Indexed: 12/21/2022]
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158
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Koo CX, Kobiyama K, Shen YJ, LeBert N, Ahmad S, Khatoo M, Aoshi T, Gasser S, Ishii KJ. RNA polymerase III regulates cytosolic RNA:DNA hybrids and intracellular microRNA expression. J Biol Chem 2015; 290:7463-73. [PMID: 25623070 PMCID: PMC4367256 DOI: 10.1074/jbc.m115.636365] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
RNA:DNA hybrids form in the nuclei and mitochondria of cells as transcription-induced R-loops or G-quadruplexes, but exist only in the cytosol of virus-infected cells. Little is known about the existence of RNA:DNA hybrids in the cytosol of virus-free cells, in particular cancer or transformed cells. Here, we show that cytosolic RNA:DNA hybrids are present in various human cell lines, including transformed cells. Inhibition of RNA polymerase III (Pol III), but not DNA polymerase, abrogated cytosolic RNA:DNA hybrids. Cytosolic RNA:DNA hybrids bind to several components of the microRNA (miRNA) machinery-related proteins, including AGO2 and DDX17. Furthermore, we identified miRNAs that are specifically regulated by Pol III, providing a potential link between RNA:DNA hybrids and the miRNA machinery. One of the target genes, exportin-1, is shown to regulate cytosolic RNA:DNA hybrids. Taken together, we reveal previously unknown mechanism by which Pol III regulates the presence of cytosolic RNA:DNA hybrids and miRNA biogenesis in various human cells.
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Affiliation(s)
- Christine Xing'er Koo
- From the Immunology Programme and Department of Microbiology, Centre for Life Sciences, and the NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, the Laboratory of Adjuvant Innovation and
| | - Kouji Kobiyama
- the Laboratory of Adjuvant Innovation and the Laboratory of Vaccine Science, World Premier International Immunology Frontier Research Center (iFREC), Osaka University, Suita, Osaka 565-0871, Japan
| | - Yu J Shen
- From the Immunology Programme and Department of Microbiology, Centre for Life Sciences, and the NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456
| | - Nina LeBert
- From the Immunology Programme and Department of Microbiology, Centre for Life Sciences, and
| | - Shandar Ahmad
- the Laboratory of Bioinformatics, National Institute of Biomedical Innovation (NIBIO), Ibaraki, Osaka 567-0085, Japan, and
| | - Muznah Khatoo
- From the Immunology Programme and Department of Microbiology, Centre for Life Sciences, and
| | - Taiki Aoshi
- the Laboratory of Adjuvant Innovation and the Laboratory of Vaccine Science, World Premier International Immunology Frontier Research Center (iFREC), Osaka University, Suita, Osaka 565-0871, Japan
| | - Stephan Gasser
- From the Immunology Programme and Department of Microbiology, Centre for Life Sciences, and the NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456,
| | - Ken J Ishii
- the Laboratory of Adjuvant Innovation and the Laboratory of Vaccine Science, World Premier International Immunology Frontier Research Center (iFREC), Osaka University, Suita, Osaka 565-0871, Japan
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159
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Minias AE, Brzostek AM, Minias P, Dziadek J. The deletion of rnhB in Mycobacterium smegmatis does not affect the level of RNase HII substrates or influence genome stability. PLoS One 2015; 10:e0115521. [PMID: 25603150 PMCID: PMC4300193 DOI: 10.1371/journal.pone.0115521] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 11/25/2014] [Indexed: 11/24/2022] Open
Abstract
RNase HII removes RNA from RNA/DNA hybrids, such as single ribonucleotides and RNA primers generated during DNA synthesis. Both, RNase HII substrates and RNase HII deficiency have been associated with genome instability in several organisms, and genome instability is a major force leading to the acquisition of drug resistance in bacteria. Understanding the mechanisms that underlie this phenomenon is one of the challenges in identifying efficient methods to combat bacterial pathogens. The aim of the present study was set to investigate the role of rnhB, presumably encoding RNase HII, in maintaining genome stability in the M. tuberculosis model organism Mycobacterium smegmatis. We performed gene replacement through homologous recombination to obtain mutant strains of Mycobacterium smegmatis lacking the rnhB gene. The mutants did not present an altered phenotype, according to the growth rate in liquid culture or susceptibility to hydroxyurea, and did not show an increase in the spontaneous mutation rate, determined using the Luria-Delbrück fluctuation test for streptomycin resistance in bacteria. The mutants also did not present an increase in the level of RNase HII substrates, measured as the level of alkaline degradation of chromosomal DNA or determined through immunodetection. We conclude that proteins other than RnhB proteins efficiently remove RNase HII substrates in M. smegmatis. These results highlight differences in the basic biology between Mycobacteria and eukaryotes and between different species of bacteria.
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Affiliation(s)
- Alina E. Minias
- Department of Genetics and Physiology of Mycobacterium, Institute of Medical Biology, Polish Academy of Sciences, Lodz, Poland
- Department of Microbiology, Biotechnology and Immunology, University of Lodz, Lodz, Poland
- * E-mail: (AM); (JD)
| | - Anna M. Brzostek
- Department of Genetics and Physiology of Mycobacterium, Institute of Medical Biology, Polish Academy of Sciences, Lodz, Poland
| | - Piotr Minias
- Department of Teacher Training and Biodiversity Studies, University of Lodz, Lodz, Poland
| | - Jaroslaw Dziadek
- Department of Genetics and Physiology of Mycobacterium, Institute of Medical Biology, Polish Academy of Sciences, Lodz, Poland
- * E-mail: (AM); (JD)
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160
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Andres SN, Schellenberg MJ, Wallace BD, Tumbale P, Williams RS. Recognition and repair of chemically heterogeneous structures at DNA ends. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2015; 56:1-21. [PMID: 25111769 PMCID: PMC4303525 DOI: 10.1002/em.21892] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Accepted: 07/28/2014] [Indexed: 05/13/2023]
Abstract
Exposure to environmental toxicants and stressors, radiation, pharmaceutical drugs, inflammation, cellular respiration, and routine DNA metabolism all lead to the production of cytotoxic DNA strand breaks. Akin to splintered wood, DNA breaks are not "clean." Rather, DNA breaks typically lack DNA 5'-phosphate and 3'-hydroxyl moieties required for DNA synthesis and DNA ligation. Failure to resolve damage at DNA ends can lead to abnormal DNA replication and repair, and is associated with genomic instability, mutagenesis, neurological disease, ageing and carcinogenesis. An array of chemically heterogeneous DNA termini arises from spontaneously generated DNA single-strand and double-strand breaks (SSBs and DSBs), and also from normal and/or inappropriate DNA metabolism by DNA polymerases, DNA ligases and topoisomerases. As a front line of defense to these genotoxic insults, eukaryotic cells have accrued an arsenal of enzymatic first responders that bind and protect damaged DNA termini, and enzymatically tailor DNA ends for DNA repair synthesis and ligation. These nucleic acid transactions employ direct damage reversal enzymes including Aprataxin (APTX), Polynucleotide kinase phosphatase (PNK), the tyrosyl DNA phosphodiesterases (TDP1 and TDP2), the Ku70/80 complex and DNA polymerase β (POLβ). Nucleolytic processing enzymes such as the MRE11/RAD50/NBS1/CtIP complex, Flap endonuclease (FEN1) and the apurinic endonucleases (APE1 and APE2) also act in the chemical "cleansing" of DNA breaks to prevent genomic instability and disease, and promote progression of DNA- and RNA-DNA damage response (DDR and RDDR) pathways. Here, we provide an overview of cellular first responders dedicated to the detection and repair of abnormal DNA termini.
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Affiliation(s)
- Sara N Andres
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, North Carolina
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161
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Pendergraft WF, Means TK. AGS, SLE, and RNASEH2 mutations: translating insights into therapeutic advances. J Clin Invest 2014; 125:102-4. [PMID: 25500879 DOI: 10.1172/jci78533] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Systemic lupus erythematosus (SLE) is a severe autoimmune disease characterized by the presence of nucleic acid- and protein-targeting autoantibodies and an aberrant type I IFN expression signature. Aicardi-Goutières syndrome (AGS) is an autosomal-recessive encephalopathy in children that is characterized by mutations in numerous nucleic acid repair enzymes and elevated IFN levels. Phenotypically, patients with AGS and SLE share many similarities. Ribonuclease H2 (RNase H2) is a nucleic acid repair enzyme that removes unwanted ribonucleotides from DNA. In this issue of the JCI, Günther and colleagues provide an in-depth investigation of the mechanisms underlying the link between defective removal of ribonucleotides in AGS and SLE, and these findings will likely serve as a strong springboard to provide novel therapeutic inroads.
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162
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Günther C, Kind B, Reijns MAM, Berndt N, Martinez-Bueno M, Wolf C, Tüngler V, Chara O, Lee YA, Hübner N, Bicknell L, Blum S, Krug C, Schmidt F, Kretschmer S, Koss S, Astell KR, Ramantani G, Bauerfeind A, Morris DL, Cunninghame Graham DS, Bubeck D, Leitch A, Ralston SH, Blackburn EA, Gahr M, Witte T, Vyse TJ, Melchers I, Mangold E, Nöthen MM, Aringer M, Kuhn A, Lüthke K, Unger L, Bley A, Lorenzi A, Isaacs JD, Alexopoulou D, Conrad K, Dahl A, Roers A, Alarcon-Riquelme ME, Jackson AP, Lee-Kirsch MA. Defective removal of ribonucleotides from DNA promotes systemic autoimmunity. J Clin Invest 2014; 125:413-24. [PMID: 25500883 DOI: 10.1172/jci78001] [Citation(s) in RCA: 172] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 10/09/2014] [Indexed: 01/22/2023] Open
Abstract
Genome integrity is continuously challenged by the DNA damage that arises during normal cell metabolism. Biallelic mutations in the genes encoding the genome surveillance enzyme ribonuclease H2 (RNase H2) cause Aicardi-Goutières syndrome (AGS), a pediatric disorder that shares features with the autoimmune disease systemic lupus erythematosus (SLE). Here we determined that heterozygous parents of AGS patients exhibit an intermediate autoimmune phenotype and demonstrated a genetic association between rare RNASEH2 sequence variants and SLE. Evaluation of patient cells revealed that SLE- and AGS-associated mutations impair RNase H2 function and result in accumulation of ribonucleotides in genomic DNA. The ensuing chronic low level of DNA damage triggered a DNA damage response characterized by constitutive p53 phosphorylation and senescence. Patient fibroblasts exhibited constitutive upregulation of IFN-stimulated genes and an enhanced type I IFN response to the immunostimulatory nucleic acid polyinosinic:polycytidylic acid and UV light irradiation, linking RNase H2 deficiency to potentiation of innate immune signaling. Moreover, UV-induced cyclobutane pyrimidine dimer formation was markedly enhanced in ribonucleotide-containing DNA, providing a mechanism for photosensitivity in RNase H2-associated SLE. Collectively, our findings implicate RNase H2 in the pathogenesis of SLE and suggest a role of DNA damage-associated pathways in the initiation of autoimmunity.
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163
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Mankan AK, Schmidt T, Chauhan D, Goldeck M, Höning K, Gaidt M, Kubarenko AV, Andreeva L, Hopfner KP, Hornung V. Cytosolic RNA:DNA hybrids activate the cGAS-STING axis. EMBO J 2014; 33:2937-46. [PMID: 25425575 DOI: 10.15252/embj.201488726] [Citation(s) in RCA: 265] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Intracellular recognition of non-self and also self-nucleic acids can result in the initiation of potent pro-inflammatory and antiviral cytokine responses. Most recently, cGAS was shown to be critical for the recognition of cytoplasmic dsDNA. Binding of dsDNA to cGAS results in the synthesis of cGAMP(2'-5'), which then binds to the endoplasmic reticulum resident protein STING. This initiates a signaling cascade that triggers the induction of an antiviral immune response. While most studies on intracellular nucleic acids have focused on dsRNA or dsDNA, it has remained unexplored whether cytosolic RNA:DNA hybrids are also sensed by the innate immune system. Studying synthetic RNA:DNA hybrids, we indeed observed a strong type I interferon response upon cytosolic delivery of this class of molecule. Studies in THP-1 knockout cells revealed that the recognition of RNA:DNA hybrids is completely attributable to the cGAS-STING pathway. Moreover, in vitro studies showed that recombinant cGAS produced cGAMP upon RNA:DNA hybrid recognition. Altogether, our results introduce RNA:DNA hybrids as a novel class of intracellular PAMP molecules and describe an alternative cGAS ligand next to dsDNA.
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Affiliation(s)
- Arun K Mankan
- Institute of Molecular Medicine, University Hospital University of Bonn, Bonn, Germany
| | - Tobias Schmidt
- Institute of Molecular Medicine, University Hospital University of Bonn, Bonn, Germany
| | - Dhruv Chauhan
- Institute of Molecular Medicine, University Hospital University of Bonn, Bonn, Germany
| | - Marion Goldeck
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital University of Bonn, Bonn, Germany
| | - Klara Höning
- Institute of Molecular Medicine, University Hospital University of Bonn, Bonn, Germany
| | - Moritz Gaidt
- Institute of Molecular Medicine, University Hospital University of Bonn, Bonn, Germany
| | - Andrew V Kubarenko
- Institute of Molecular Medicine, University Hospital University of Bonn, Bonn, Germany
| | - Liudmila Andreeva
- Department of Biochemistry and Gene Center, Ludwig-Maximilians-University, Munich, Germany
| | - Karl-Peter Hopfner
- Department of Biochemistry and Gene Center, Ludwig-Maximilians-University, Munich, Germany
| | - Veit Hornung
- Institute of Molecular Medicine, University Hospital University of Bonn, Bonn, Germany
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164
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El Hage A, Webb S, Kerr A, Tollervey D. Genome-wide distribution of RNA-DNA hybrids identifies RNase H targets in tRNA genes, retrotransposons and mitochondria. PLoS Genet 2014; 10:e1004716. [PMID: 25357144 PMCID: PMC4214602 DOI: 10.1371/journal.pgen.1004716] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Accepted: 08/27/2014] [Indexed: 01/08/2023] Open
Abstract
During transcription, the nascent RNA can invade the DNA template, forming extended RNA-DNA duplexes (R-loops). Here we employ ChIP-seq in strains expressing or lacking RNase H to map targets of RNase H activity throughout the budding yeast genome. In wild-type strains, R-loops were readily detected over the 35S rDNA region, transcribed by Pol I, and over the 5S rDNA, transcribed by Pol III. In strains lacking RNase H activity, R-loops were elevated over other Pol III genes, notably tRNAs, SCR1 and U6 snRNA, and were also associated with the cDNAs of endogenous TY1 retrotransposons, which showed increased rates of mobility to the 5′-flanking regions of tRNA genes. Unexpectedly, R-loops were also associated with mitochondrial genes in the absence of RNase H1, but not of RNase H2. Finally, R-loops were detected on actively transcribed protein-coding genes in the wild-type, particularly over the second exon of spliced ribosomal protein genes. R-loops (RNA-DNA hybrids) are potentially deleterious for gene expression and genome stability, but can be beneficial, for example, during immunoglobulin gene class-switch recombination. Here we made use of antibody S9.6, with specificity for RNA-DNA duplexes independently of their sequence. The genome-wide distribution of R-loops in wild-type yeast showed association with the highly transcribed ribosomal DNA, and protein-coding genes, particularly the second exon of spliced genes. On RNA polymerase III loci such as the highly transcribed transfer RNA genes (tRNAs), R-loop accumulation was strongly detected in the absence of both ribonucleases H1 and H2 (RNase H1 and H2), indicating that R-loops are inherently formed but rapidly cleared by RNase H. Importantly, stable R-loops lead to reduced synthesis of tRNA precursors in mutants lacking RNase H and DNA topoisomerase activities. RNA-DNA hybrids associated with TY1 cDNA retrotransposition intermediates were elevated in the absence of RNase H, and this was accompanied by increased retrotransposition, in particular to 5′-flanking regions of tRNAs. Our findings show that RNase H participates in silencing of TY1 life cycle. Surprisingly, R-loops associated with mitochondrial transcription units were suppressed specifically by RNase H1. These findings have potentially important implications for understanding human diseases caused by mutations in RNase H.
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Affiliation(s)
- Aziz El Hage
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail: (AEH); (DT)
| | - Shaun Webb
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Alastair Kerr
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail: (AEH); (DT)
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165
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Divalent metal ion-induced folding mechanism of RNase H1 from extreme halophilic archaeon Halobacterium sp. NRC-1. PLoS One 2014; 9:e109016. [PMID: 25268753 PMCID: PMC4182655 DOI: 10.1371/journal.pone.0109016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Accepted: 08/28/2014] [Indexed: 01/23/2023] Open
Abstract
RNase H1 from Halobacterium sp. NRC-1 (Halo-RNase H1) is characterized by the abundance of acidic residues on the surface, including bi/quad-aspartate site residues. Halo-RNase H1 exists in partially folded (I) and native (N) states in low-salt and high-salt conditions respectively. Its folding is also induced by divalent metal ions. To understand this unique folding mechanism of Halo-RNase H1, the active site mutant (2A-RNase H1), the bi/quad-aspartate site mutant (6A-RNase H1), and the mutant at both sites (8A-RNase H1) were constructed. The far-UV CD spectra of these mutants suggest that 2A-RNase H1 mainly exists in the I state, 6A-RNase H1 exists both in the I and N states, and 8A-RNase H1 mainly exists in the N state in a low salt-condition. These results suggest that folding of Halo-RNase H1 is induced by binding of divalent metal ions to the bi/quad-aspartate site. To examine whether metal-induced folding is unique to Halo-RNase H1, RNase H2 from the same organism (Halo-RNase H2) was overproduced and purified. Halo-RNase H2 exists in the I and N states in low-salt and high-salt conditions respectively, as does Halo-RNase H1. However, this protein exists in the I state even in the presence of divalent metal ions. Halo-RNase H2 exhibits junction ribonuclease activity only in a high-salt condition. A tertiary model of this protein suggests that this protein does not have a quad-aspartate site. We propose that folding of Halo-RNase H1 is induced by binding of divalent metal ion to the quad-aspartate site in a low-salt condition.
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166
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Pizzi S, Sertic S, Orcesi S, Cereda C, Bianchi M, Jackson AP, Lazzaro F, Plevani P, Muzi-Falconi M. Reduction of hRNase H2 activity in Aicardi-Goutières syndrome cells leads to replication stress and genome instability. Hum Mol Genet 2014; 24:649-58. [PMID: 25274781 PMCID: PMC4291245 DOI: 10.1093/hmg/ddu485] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Aicardi-Goutières syndrome (AGS) is an inflammatory encephalopathy caused by defective nucleic acids metabolism. Over 50% of AGS mutations affect RNase H2 the only enzyme able to remove single ribonucleotide-monophosphates (rNMPs) embedded in DNA. Ribonucleotide triphosphates (rNTPs) are incorporated into genomic DNA with relatively high frequency during normal replication making DNA more susceptible to strand breakage and mutations. Here we demonstrate that human cells depleted of RNase H2 show impaired cell cycle progression associated with chronic activation of post-replication repair (PRR) and genome instability. We identify a similar phenotype in cells derived from AGS patients, which indeed accumulate rNMPs in genomic DNA and exhibit markers of constitutive PRR and checkpoint activation. Our data indicate that in human cells RNase H2 plays a crucial role in correcting rNMPs misincorporation, preventing DNA damage. Such protective function is compromised in AGS patients and may be linked to unscheduled immune responses. These findings may be relevant to shed further light on the mechanisms involved in AGS pathogenesis.
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Affiliation(s)
- Sara Pizzi
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | - Sarah Sertic
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | | | - Cristina Cereda
- Laboratory of Experimental Neurobiology, C. Mondino National Neurological Institute, Pavia, Italy and
| | - Marika Bianchi
- Laboratory of Experimental Neurobiology, C. Mondino National Neurological Institute, Pavia, Italy and
| | - Andrew P Jackson
- Medical Research Council Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Federico Lazzaro
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | - Paolo Plevani
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | - Marco Muzi-Falconi
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
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167
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Abstract
R-loops are cellular structures composed of an RNA/DNA hybrid, which is formed when the RNA hybridises to a complementary DNA strand and a displaced single-stranded DNA. R-loops have been detected in various organisms from bacteria to mammals and play crucial roles in regulating gene expression, DNA and histone modifications, immunoglobulin class switch recombination, DNA replication, and genome stability. Recent evidence suggests that R-loops are also involved in molecular mechanisms of neurological diseases and cancer. In addition, mutations in factors implicated in R-loop biology, such as RNase H and SETX (senataxin), lead to devastating human neurodegenerative disorders, highlighting the importance of correctly regulating the level of R-loops in human cells. In this review we summarise current advances in this field, with a particular focus on diseases associated with dysregulation of R-loop structures. We also discuss potential therapeutic approaches for such diseases and highlight future research directions.
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Affiliation(s)
- Matthias Groh
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Natalia Gromak
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
- * E-mail:
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168
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Kalhorzadeh P, Hu Z, Cools T, Amiard S, Willing EM, De Winne N, Gevaert K, De Jaeger G, Schneeberger K, White CI, De Veylder L. Arabidopsis thaliana RNase H2 deficiency counteracts the needs for the WEE1 checkpoint kinase but triggers genome instability. THE PLANT CELL 2014; 26:3680-92. [PMID: 25217508 PMCID: PMC4213155 DOI: 10.1105/tpc.114.128108] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The WEE1 kinase is an essential cell cycle checkpoint regulator in Arabidopsis thaliana plants experiencing replication defects. Whereas under non-stress conditions WEE1-deficient plants develop normally, they fail to adapt to replication inhibitory conditions, resulting in the accumulation of DNA damage and loss of cell division competence. We identified mutant alleles of the genes encoding subunits of the ribonuclease H2 (RNase H2) complex, known for its role in removing ribonucleotides from DNA-RNA duplexes, as suppressor mutants of WEE1 knockout plants. RNase H2 deficiency triggered an increase in homologous recombination (HR), correlated with the accumulation of γ-H2AX foci. However, as HR negatively impacts the growth of WEE1-deficient plants under replication stress, it cannot account for the rescue of the replication defects of the WEE1 knockout plants. Rather, the observed increase in ribonucleotide incorporation in DNA indicates that the substitution of deoxynucleotide with ribonucleotide abolishes the need for WEE1 under replication stress. Strikingly, increased ribonucleotide incorporation in DNA correlated with the occurrence of small base pair deletions, identifying the RNase H2 complex as an important suppressor of genome instability.
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Affiliation(s)
- Pooneh Kalhorzadeh
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), B-9052 Ghent, Belgium Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium
| | - Zhubing Hu
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), B-9052 Ghent, Belgium Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium
| | - Toon Cools
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), B-9052 Ghent, Belgium Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium
| | - Simon Amiard
- Génétique, Reproduction et Développement, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6293-Clermont Université-Institut National de la Santé et de la Recherche Médicale U1103, F-63177 Aubière, France
| | - Eva-Maria Willing
- Department for Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
| | - Nancy De Winne
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), B-9052 Ghent, Belgium Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium
| | - Kris Gevaert
- Department of Medical Protein Research, Flanders Institute for Biotechnology (VIB), B-9000 Ghent, Belgium Department of Biochemistry, Ghent University, B-9000 Ghent, Belgium
| | - Geert De Jaeger
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), B-9052 Ghent, Belgium Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium
| | - Korbinian Schneeberger
- Department for Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
| | - Charles I White
- Génétique, Reproduction et Développement, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6293-Clermont Université-Institut National de la Santé et de la Recherche Médicale U1103, F-63177 Aubière, France
| | - Lieven De Veylder
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), B-9052 Ghent, Belgium Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium
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169
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Potenski CJ, Klein HL. How the misincorporation of ribonucleotides into genomic DNA can be both harmful and helpful to cells. Nucleic Acids Res 2014; 42:10226-34. [PMID: 25159610 PMCID: PMC4176331 DOI: 10.1093/nar/gku773] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Ribonucleotides are misincorporated into replicating DNA due to the similarity of deoxyribonucleotides and ribonucleotides, the high concentration of ribonucleotides in the nucleus and the imperfect accuracy of replicative DNA polymerases in choosing the base with the correct sugar. Embedded ribonucleotides change certain properties of the DNA and can interfere with normal DNA transactions. Therefore, misincorporated ribonucleotides are targeted by the cell for removal. Failure to remove ribonucleotides from DNA results in an increase in genome instability, a phenomenon that has been characterized in various systems using multiple assays. Recently, however, another side to ribonucleotide misincorporation has emerged, where there is evidence for a functional role of misinserted ribonucleotides in DNA, leading to beneficial consequences for the cell. This review examines examples of both positive and negative effects of genomic ribonucleotide misincorporation in various organisms, aiming to highlight the diversity and the utility of this common replication variation.
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Affiliation(s)
- Catherine J Potenski
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Hannah L Klein
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
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170
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Volkman HE, Stetson DB. The enemy within: endogenous retroelements and autoimmune disease. Nat Immunol 2014; 15:415-22. [PMID: 24747712 DOI: 10.1038/ni.2872] [Citation(s) in RCA: 205] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 03/21/2014] [Indexed: 02/07/2023]
Abstract
Inappropriate or chronic detection of self nucleic acids by the innate immune system underlies many human autoimmune diseases. We discuss here an unexpected source of endogenous immunostimulatory nucleic acids: the reverse-transcribed cDNA of endogenous retroelements. The interplay between innate immune sensing and clearance of retroelement cDNA has important implications for the understanding of immune responses to infectious retroviruses such as human immunodeficiency virus (HIV). Furthermore, the detection of cDNA by the innate immune system reveals an evolutionary tradeoff: selection for a vigorous, sensitive response to infectious retroviruses may predispose the inappropriate detection of endogenous retroelements. We propose that this tradeoff has placed unique constraints on the sensitivity of the DNA-activated antiviral response, with implications for the interactions of DNA viruses and retroviruses with their hosts. Finally, we discuss how better understanding of the intersection of retroelement biology and innate immunity can guide the way to novel therapies for specific autoimmune diseases.
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Affiliation(s)
- Hannah E Volkman
- Department of Immunology, University of Washington School of Medicine, Seattle, Washington, USA
| | - Daniel B Stetson
- Department of Immunology, University of Washington School of Medicine, Seattle, Washington, USA
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171
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Kind B, Muster B, Staroske W, Herce HD, Sachse R, Rapp A, Schmidt F, Koss S, Cardoso MC, Lee-Kirsch MA. Altered spatio-temporal dynamics of RNase H2 complex assembly at replication and repair sites in Aicardi-Goutières syndrome. Hum Mol Genet 2014; 23:5950-60. [PMID: 24986920 DOI: 10.1093/hmg/ddu319] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Ribonuclease H2 plays an essential role for genome stability as it removes ribonucleotides misincorporated into genomic DNA by replicative polymerases and resolves RNA/DNA hybrids. Biallelic mutations in the genes encoding the three RNase H2 subunits cause Aicardi-Goutières syndrome (AGS), an early-onset inflammatory encephalopathy that phenotypically overlaps with the autoimmune disorder systemic lupus erythematosus. Here we studied the intracellular dynamics of RNase H2 in living cells during DNA replication and in response to DNA damage using confocal time-lapse imaging and fluorescence cross-correlation spectroscopy. We demonstrate that the RNase H2 complex is assembled in the cytosol and imported into the nucleus in an RNase H2B-dependent manner. RNase H2 is not only recruited to DNA replication foci, but also to sites of PCNA-dependent DNA repair. By fluorescence recovery after photobleaching, we demonstrate a high mobility and fast exchange of RNase H2 at sites of DNA repair and replication. We provide evidence that recruitment of RNase H2 is not only PCNA-dependent, mediated by an interaction of the B subunit with PCNA, but also PCNA-independent mediated via the catalytic domain of the A subunit. We found that AGS-associated mutations alter complex formation, recruitment efficiency and exchange kinetics at sites of DNA replication and repair suggesting that impaired ribonucleotide removal contributes to AGS pathogenesis.
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Affiliation(s)
- Barbara Kind
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus and
| | - Britta Muster
- Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Wolfgang Staroske
- Biotechnology Center, Technische Universität Dresden, 01307 Dresden, Germany
| | - Henry D Herce
- Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, New York 12180-3590, USA and
| | - René Sachse
- Institute of Earth and Environmental Science, Potsdam University, 14476 Potsdam, Germany
| | - Alexander Rapp
- Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Franziska Schmidt
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus and
| | - Sarah Koss
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus and
| | - M Cristina Cardoso
- Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany,
| | - Min Ae Lee-Kirsch
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus and
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172
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DNA ligase C1 mediates the LigD-independent nonhomologous end-joining pathway of Mycobacterium smegmatis. J Bacteriol 2014; 196:3366-76. [PMID: 24957619 DOI: 10.1128/jb.01832-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Nonhomologous end joining (NHEJ) is a recently described bacterial DNA double-strand break (DSB) repair pathway that has been best characterized for mycobacteria. NHEJ can religate transformed linear plasmids, repair ionizing radiation (IR)-induced DSBs in nonreplicating cells, and seal I-SceI-induced chromosomal DSBs. The core components of the mycobacterial NHEJ machinery are the DNA end binding protein Ku and the polyfunctional DNA ligase LigD. LigD has three autonomous enzymatic modules: ATP-dependent DNA ligase (LIG), DNA/RNA polymerase (POL), and 3' phosphoesterase (PE). Although genetic ablation of ku or ligD abolishes NHEJ and sensitizes nonreplicating cells to ionizing radiation, selective ablation of the ligase activity of LigD in vivo only mildly impairs NHEJ of linearized plasmids, indicating that an additional DNA ligase can support NHEJ. Additionally, the in vivo role of the POL and PE domains in NHEJ is unclear. Here we define a LigD ligase-independent NHEJ pathway in Mycobacterium smegmatis that requires the ATP-dependent DNA ligase LigC1 and the POL domain of LigD. Mycobacterium tuberculosis LigC can also support this backup NHEJ pathway. We also demonstrate that, although dispensable for efficient plasmid NHEJ, the activities of the POL and PE domains are required for repair of IR-induced DSBs in nonreplicating cells. These findings define the genetic requirements for a LigD-independent NHEJ pathway in mycobacteria and demonstrate that all enzymatic functions of the LigD protein participate in NHEJ in vivo.
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173
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Mottaghi-Dastjerdi N, Soltany-Rezaee-Rad M, Sepehrizadeh Z, Roshandel G, Ebrahimifard F, Setayesh N. Identification of novel genes involved in gastric carcinogenesis by suppression subtractive hybridization. Hum Exp Toxicol 2014; 34:3-11. [PMID: 24812152 DOI: 10.1177/0960327114532386] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Gastric cancer (GC) is one of the most common and life-threatening types of malignancies. Identification of the differentially expressed genes in GC is one of the best approaches for establishing new diagnostic and therapeutic targets. Furthermore, these investigations could advance our knowledge about molecular biology and the carcinogenesis of this cancer. To screen for the overexpressed genes in gastric adenocarcinoma, we performed suppression subtractive hybridization (SSH) on gastric adenocarcinoma tissue and the corresponding normal gastric tissue, and eight genes were found to be overexpressed in the tumor compared with those of the normal tissue. The genes were ribosomal protein L18A, RNase H2 subunit B, SEC13, eukaryotic translation initiation factor 4A1, tetraspanin 8, cytochrome c oxidase subunit 2, NADH dehydrogenase subunit 4, and mitochondrially encoded ATP synthase 6. The common functions among the identified genes include involvement in protein synthesis, involvement in genomic stability maintenance, metastasis, metabolic improvement, cell signaling pathways, and chemoresistance. Our results provide new insights into the molecular biology of GC and drug discovery: each of the identified genes could be further investigated as targets for prognosis evaluation, diagnosis, treatment, evaluation of the response to new anticancer drugs, and determination of the molecular pathogenesis of GC.
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Affiliation(s)
- N Mottaghi-Dastjerdi
- Department of Pharmaceutical Biotechnology and Pharmaceutical Biotechnology Research Center, School of Pharmacy, Tehran University of Medical Sciences, Tehran, Islamic Republic of Iran Pharmaceutical Sciences Research Center, Sari School of Pharmacy, Mazandaran University of Medical Sciences, Sari, Islamic Republic of Iran
| | - M Soltany-Rezaee-Rad
- Department of Pharmaceutical Biotechnology and Pharmaceutical Biotechnology Research Center, School of Pharmacy, Tehran University of Medical Sciences, Tehran, Islamic Republic of Iran Pharmaceutical Sciences Research Center, Sari School of Pharmacy, Mazandaran University of Medical Sciences, Sari, Islamic Republic of Iran
| | - Z Sepehrizadeh
- Department of Pharmaceutical Biotechnology and Pharmaceutical Biotechnology Research Center, School of Pharmacy, Tehran University of Medical Sciences, Tehran, Islamic Republic of Iran
| | - G Roshandel
- Golestan Research Center of Gastroenterology and Hepatology, Golestan University of Medical Sciences, Golestan, Islamic Republic of Iran
| | - F Ebrahimifard
- Department of General Surgery, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Islamic Republic of Iran
| | - N Setayesh
- Department of Pharmaceutical Biotechnology and Pharmaceutical Biotechnology Research Center, School of Pharmacy, Tehran University of Medical Sciences, Tehran, Islamic Republic of Iran
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174
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Abstract
While primordial life is thought to have been RNA-based (Cech, Cold Spring Harbor Perspect. Biol. 4 (2012) a006742), all living organisms store genetic information in DNA, which is chemically more stable. Distinctions between the RNA and DNA worlds and our views of "DNA" synthesis continue to evolve as new details emerge on the incorporation, repair and biological effects of ribonucleotides in DNA genomes of organisms from bacteria through humans.
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Affiliation(s)
- Jessica S Williams
- Laboratory of Molecular Genetics and Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, United States
| | - Thomas A Kunkel
- Laboratory of Molecular Genetics and Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, United States.
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175
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Allen-Soltero S, Martinez SL, Putnam CD, Kolodner RD. A saccharomyces cerevisiae RNase H2 interaction network functions to suppress genome instability. Mol Cell Biol 2014; 34:1521-34. [PMID: 24550002 PMCID: PMC3993591 DOI: 10.1128/mcb.00960-13] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 08/23/2013] [Accepted: 02/04/2014] [Indexed: 11/20/2022] Open
Abstract
Errors during DNA replication are one likely cause of gross chromosomal rearrangements (GCRs). Here, we analyze the role of RNase H2, which functions to process Okazaki fragments, degrade transcription intermediates, and repair misincorporated ribonucleotides, in preventing genome instability. The results demonstrate that rnh203 mutations result in a weak mutator phenotype and cause growth defects and synergistic increases in GCR rates when combined with mutations affecting other DNA metabolism pathways, including homologous recombination (HR), sister chromatid HR, resolution of branched HR intermediates, postreplication repair, sumoylation in response to DNA damage, and chromatin assembly. In some cases, a mutation in RAD51 or TOP1 suppressed the increased GCR rates and/or the growth defects of rnh203Δ double mutants. This analysis suggests that cells with RNase H2 defects have increased levels of DNA damage and depend on other pathways of DNA metabolism to overcome the deleterious effects of this DNA damage.
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Affiliation(s)
- Stephanie Allen-Soltero
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, USA
- Department of Medicine, University of California School of Medicine, San Diego, La Jolla, California, USA
- Department of Cellular and Molecular Medicine, University of California School of Medicine, San Diego, La Jolla, California, USA
| | - Sandra L. Martinez
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, USA
| | - Christopher D. Putnam
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, USA
- Department of Medicine, University of California School of Medicine, San Diego, La Jolla, California, USA
| | - Richard D. Kolodner
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, USA
- Department of Medicine, University of California School of Medicine, San Diego, La Jolla, California, USA
- Department of Cellular and Molecular Medicine, University of California School of Medicine, San Diego, La Jolla, California, USA
- Moores-UCSD Cancer Center, University of California School of Medicine, San Diego, La Jolla, California, USA
- Institute of Genomic Medicine, University of California School of Medicine, San Diego, La Jolla, California, USA
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176
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Behrendt R, Roers A. Mouse models for Aicardi-Goutières syndrome provide clues to the molecular pathogenesis of systemic autoimmunity. Clin Exp Immunol 2014; 175:9-16. [PMID: 23713592 DOI: 10.1111/cei.12147] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2013] [Indexed: 12/31/2022] Open
Abstract
Aicardi-Goutières syndrome (AGS) is a hereditary autoimmune disease which overlaps clinically and pathogenetically with systemic lupus erythematosus (SLE), and can be regarded as a monogenic variant of SLE. Both conditions are characterized by chronic activation of anti-viral type I interferon (IFN) responses. AGS can be caused by mutations in one of several genes encoding intracellular enzymes all involved in nucleic acid metabolism. Mouse models of AGS-associated defects yielded distinct phenotypes and reproduced important features of the disease. Analysis of these mutant mouse lines stimulated a new concept of autoimmunity caused by intracellular accumulations of nucleic acids, which trigger a chronic cell-intrinsic antiviral type I IFN response and thereby autoimmunity. This model is of major relevance for our understanding of SLE pathogenesis. Findings in gene-targeted mice deficient for AGS associated enzymes are summarized in this review.
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Affiliation(s)
- R Behrendt
- Institute for Immunology, Medical Faculty Carl Gustav Carus, University of Technology Dresden, Dresden, Germany
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177
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Lee-Kirsch MA, Wolf C, Günther C. Aicardi-Goutières syndrome: a model disease for systemic autoimmunity. Clin Exp Immunol 2014; 175:17-24. [PMID: 23786362 DOI: 10.1111/cei.12160] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2013] [Indexed: 02/06/2023] Open
Abstract
Systemic autoimmunity is a complex disease process that results from a loss of immunological tolerance characterized by the inability of the immune system to discriminate self from non-self. In patients with the prototypic autoimmune disease systemic lupus erythematosus (SLE), formation of autoantibodies targeting ubiquitous nuclear antigens and subsequent deposition of immune complexes in the vascular bed induces inflammatory tissue injury that can affect virtually any organ system. Given the extraordinary genetic and phenotypic heterogeneity of SLE, one approach to the genetic dissection of complex SLE is to study monogenic diseases, for which a single gene defect is responsible. Considerable success has been achieved from the analysis of the rare monogenic disorder Aicardi-Goutières syndrome (AGS), an inflammatory encephalopathy that clinically resembles in-utero-acquired viral infection and that also shares features with SLE. Progress in understanding the cellular and molecular functions of the AGS causing genes has revealed novel pathways of the metabolism of intracellular nucleic acids, the major targets of the autoimmune attack in patients with SLE. Induction of autoimmunity initiated by immune recognition of endogenous nucleic acids originating from processes such as DNA replication/repair or endogenous retro-elements represents novel paradigms of SLE pathogenesis. These findings illustrate how investigating rare monogenic diseases can also fuel discoveries that advance our understanding of complex disease. This will not only aid the development of improved tools for SLE diagnosis and disease classification, but also the development of novel targeted therapeutic approaches.
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Affiliation(s)
- M A Lee-Kirsch
- Department of Pediatrics, University Hospital, Technical University Dresden, Dresden, Germany
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178
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Avila J, Gómez-Ramos A, Soriano E. Variations in brain DNA. Front Aging Neurosci 2014; 6:323. [PMID: 25505410 PMCID: PMC4243573 DOI: 10.3389/fnagi.2014.00323] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 11/06/2014] [Indexed: 12/16/2022] Open
Abstract
It is assumed that DNA sequences are conserved in the diverse cell types present in a multicellular organism like the human being. Thus, in order to compare the sequences in the genome of DNA from different individuals, nucleic acid is commonly isolated from a single tissue. In this regard, blood cells are widely used for this purpose because of their availability. Thus blood DNA has been used to study genetic familiar diseases that affect other tissues and organs, such as the liver, heart, and brain. While this approach is valid for the identification of familial diseases in which mutations are present in parental germinal cells and, therefore, in all the cells of a given organism, it is not suitable to identify sporadic diseases in which mutations might occur in specific somatic cells. This review addresses somatic DNA variations in different tissues or cells (mainly in the brain) of single individuals and discusses whether the dogma of DNA invariance between cell types is indeed correct. We will also discuss how single nucleotide somatic variations arise, focusing on the presence of specific DNA mutations in the brain.
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Affiliation(s)
- Jesús Avila
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), ISCIIIMadrid, Spain
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Neurobiology LaboratoryMadrid, Spain
- *Correspondence: Jesús Avila, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Neurobiology Laboratory, 208, C/ Nicolás Cabrera no. 1, Madrid, 28049, Spain e-mail: ; Eduardo Soriano, Department of Cell Biology, Faculty of Biology, University of Barcelona, Developmental Neurobiology and Regeneration Lab, Parc Científic de Barcelona, Baldiri i Reixac, 10, Barcelona 08028, Spain e-mail:
| | - Alberto Gómez-Ramos
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), ISCIIIMadrid, Spain
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Neurobiology LaboratoryMadrid, Spain
| | - Eduardo Soriano
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), ISCIIIMadrid, Spain
- Department of Cell Biology, Faculty of Biology, University of Barcelona, Developmental Neurobiology and Regeneration Lab, Parc Científic de BarcelonaBarcelona, Spain
- Vall d’Hebrón Institut de Recerca (VHIR)Barcelona, Spain
- *Correspondence: Jesús Avila, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Neurobiology Laboratory, 208, C/ Nicolás Cabrera no. 1, Madrid, 28049, Spain e-mail: ; Eduardo Soriano, Department of Cell Biology, Faculty of Biology, University of Barcelona, Developmental Neurobiology and Regeneration Lab, Parc Científic de Barcelona, Baldiri i Reixac, 10, Barcelona 08028, Spain e-mail:
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179
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Sze A, Olagnier D, Lin R, van Grevenynghe J, Hiscott J. SAMHD1 Host Restriction Factor: A Link with Innate Immune Sensing of Retrovirus Infection. J Mol Biol 2013; 425:4981-94. [DOI: 10.1016/j.jmb.2013.10.022] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Revised: 10/15/2013] [Accepted: 10/16/2013] [Indexed: 02/02/2023]
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180
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Removal of misincorporated ribonucleotides from prokaryotic genomes: an unexpected role for nucleotide excision repair. PLoS Genet 2013; 9:e1003878. [PMID: 24244177 PMCID: PMC3820734 DOI: 10.1371/journal.pgen.1003878] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 08/29/2013] [Indexed: 12/02/2022] Open
Abstract
Stringent steric exclusion mechanisms limit the misincorporation of ribonucleotides by high-fidelity DNA polymerases into genomic DNA. In contrast, low-fidelity Escherichia coli DNA polymerase V (pol V) has relatively poor sugar discrimination and frequently misincorporates ribonucleotides. Substitution of a steric gate tyrosine residue with alanine (umuC_Y11A) reduces sugar selectivity further and allows pol V to readily misincorporate ribonucleotides as easily as deoxynucleotides, whilst leaving its poor base-substitution fidelity essentially unchanged. However, the mutability of cells expressing the steric gate pol V mutant is very low due to efficient repair mechanisms that are triggered by the misincorporated rNMPs. Comparison of the mutation frequency between strains expressing wild-type and mutant pol V therefore allows us to identify pathways specifically directed at ribonucleotide excision repair (RER). We previously demonstrated that rNMPs incorporated by umuC_Y11A are efficiently removed from DNA in a repair pathway initiated by RNase HII. Using the same approach, we show here that mismatch repair and base excision repair play minimal back-up roles in RER in vivo. In contrast, in the absence of functional RNase HII, umuC_Y11A-dependent mutagenesis increases significantly in ΔuvrA, uvrB5 and ΔuvrC strains, suggesting that rNMPs misincorporated into DNA are actively repaired by nucleotide excision repair (NER) in vivo. Participation of NER in RER was confirmed by reconstituting ribonucleotide-dependent NER in vitro. We show that UvrABC nuclease-catalyzed incisions are readily made on DNA templates containing one, two, or five rNMPs and that the reactions are stimulated by the presence of mispaired bases. Similar to NER of DNA lesions, excision of rNMPs proceeds through dual incisions made at the 8th phosphodiester bond 5′ and 4th–5th phosphodiester bonds 3′ of the ribonucleotide. Ribonucleotides misinserted into DNA can therefore be added to the broad list of helix-distorting modifications that are substrates for NER. Most DNA polymerases differentiate between ribo- and deoxyribonucleotides quite effectively, thereby deterring insertion of nucleotides with the “wrong” sugar into chromosomes. Nevertheless, a significant number of ribonucleotides still get stably incorporated into genomic DNA. E.coli pol V is among the most inaccurate DNA polymerases in terms of both sugar selectivity and base substitution fidelity. The umuC_Y11A steric gate variant of pol V is even less discriminating when selecting sugar of the incoming nucleotide while keeping a similar capacity to form non-Watson-Crick base pairs. In the present study, we describe mechanisms employed by E. coli to excise rNMPs from DNA and to concomitantly reduce the extent of spontaneous mutagenesis induced by umuC_Y11A. The first line of defense comes from Ribonuclease HII, which initiates the ribonucleotide excision repair pathway. In the absence of RNase HII, alternate repair pathways help remove the misincorporated ribonucleotides. Here, we present the first direct evidence that nucleotide excision repair (NER) has the capacity to recognize both correctly and incorrectly paired rNMPs embedded in DNA. The combined actions of RNase HII and NER thereby reduce the mutagenic potential of ribonucleotides errantly incorporated into prokaryotic genomes.
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181
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Structure-function analysis of ribonucleotide bypass by B family DNA replicases. Proc Natl Acad Sci U S A 2013; 110:16802-7. [PMID: 24082122 DOI: 10.1073/pnas.1309119110] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Ribonucleotides are frequently incorporated into DNA during replication, they are normally removed, and failure to remove them results in replication stress. This stress correlates with DNA polymerase (Pol) stalling during bypass of ribonucleotides in DNA templates. Here we demonstrate that stalling by yeast replicative Pols δ and ε increases as the number of consecutive template ribonucleotides increases from one to four. The homologous bacteriophage RB69 Pol also stalls during ribonucleotide bypass, with a pattern most similar to that of Pol ε. Crystal structures of an exonuclease-deficient variant of RB69 Pol corresponding to multiple steps in single ribonucleotide bypass reveal that increased stalling is associated with displacement of Tyr391 and an unpreferred C2'-endo conformation for the ribose. Even less efficient bypass of two consecutive ribonucleotides in DNA correlates with similar movements of Tyr391 and displacement of one of the ribonucleotides along with the primer-strand DNA backbone. These structure-function studies have implications for cellular signaling by ribonucleotides, and they may be relevant to replication stress in cells defective in ribonucleotide excision repair, including humans suffering from autoimmune disease associated with RNase H2 defects.
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182
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Kim J, Yoon J, Ju M, Lee Y, Kim TH, Kim J, Sommer P, No Z, Cechetto J, Han SJ. Identification of two HIV inhibitors that also inhibit human RNaseH2. Mol Cells 2013; 36:212-8. [PMID: 24008364 PMCID: PMC3887976 DOI: 10.1007/s10059-013-2348-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 07/01/2013] [Accepted: 07/03/2013] [Indexed: 10/26/2022] Open
Abstract
A total of 140,000 compounds were screened in a targetfree cell-based high throughput assay against HIV-1 infection, and a subset of 81 promising compounds was identified. Secondary screening of these 81 compounds revealed two putative human RNaseH2 inhibitors, RHI001 and RHI002, with IC50 value of 6.8 μM and 16 μM, respectively. RHI002 showed selective activity against human RNaseH2 while RHI001 inhibited HIV-RNaseH, E. coli RNaseH, and human RNaseH1 with IC50 value of 28.5 μM, 7.9 μM, and 31.7 μM, respectively. Kinetic analysis revealed that both inhibitors had non-competitive inhibitor-like properties. Because RNaseH2 is involved in the etiology of Aicardi-Goutier syndrome and has been suggested as an anticancer drug target, small molecule inhibitors modulating its activity would be useful for investigating the cellular function of this molecule.
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Affiliation(s)
- Junghwan Kim
- Drug Biology Group, Institut Pasteur Korea, Seongnam 463-400, Korea
| | - Jaewan Yoon
- Drug Biology Group, Institut Pasteur Korea, Seongnam 463-400, Korea
| | - MoonKyeong Ju
- Drug Biology Group, Institut Pasteur Korea, Seongnam 463-400, Korea
| | - Yunmi Lee
- Drug Biology Group, Institut Pasteur Korea, Seongnam 463-400, Korea
| | - Tae-Hee Kim
- Screening Technology Platforms Group, Institut Pasteur Korea, Seongnam 463-400, Korea
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Junwon Kim
- Medicinal Chemistry Group, Institute Pasteur Korea, Seongnam 463-400, Korea
| | - Peter Sommer
- Cell Biology of Retroviruses Group, Institut Pasteur Korea, Seongnam 463-400, Korea
| | - Zaesung No
- Medicinal Chemistry Group, Institute Pasteur Korea, Seongnam 463-400, Korea
| | - Jonathan Cechetto
- Screening Technology Platforms Group, Institut Pasteur Korea, Seongnam 463-400, Korea
| | - Sung-Jun Han
- Drug Biology Group, Institut Pasteur Korea, Seongnam 463-400, Korea
- Department of Biological Sciences, Konkuk University, Seoul 143-701, Korea
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183
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Behrendt R, Schumann T, Gerbaulet A, Nguyen LA, Schubert N, Alexopoulou D, Berka U, Lienenklaus S, Peschke K, Gibbert K, Wittmann S, Lindemann D, Weiss S, Dahl A, Naumann R, Dittmer U, Kim B, Mueller W, Gramberg T, Roers A. Mouse SAMHD1 has antiretroviral activity and suppresses a spontaneous cell-intrinsic antiviral response. Cell Rep 2013; 4:689-96. [PMID: 23972988 PMCID: PMC4807655 DOI: 10.1016/j.celrep.2013.07.037] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 06/27/2013] [Accepted: 07/25/2013] [Indexed: 12/01/2022] Open
Abstract
Aicardi-Goutières syndrome (AGS), a hereditary autoimmune disease, clinically and biochemically overlaps with systemic lupus erythematosus (SLE) and, like SLE, is characterized by spontaneous type I interferon (IFN) production. The finding that defects of intracellular nucleases cause AGS led to the concept that intracellular accumulation of nucleic acids triggers inappropriate production of type I IFN and autoimmunity. AGS can also be caused by defects of SAMHD1, a 3' exonuclease and deoxynucleotide (dNTP) triphosphohydrolase. Human SAMHD1 is an HIV-1 restriction factor that hydrolyzes dNTPs and decreases their concentration below the levels required for retroviral reverse transcription. We show in gene-targeted mice that also mouse SAMHD1 reduces cellular dNTP concentrations and restricts retroviral replication in lymphocytes, macrophages, and dendritic cells. Importantly, the absence of SAMHD1 triggered IFN-β-dependent transcriptional upregulation of type I IFN-inducible genes in various cell types indicative of spontaneous IFN production. SAMHD1-deficient mice may be instrumental for elucidating the mechanisms that trigger pathogenic type I IFN responses in AGS and SLE.
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184
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Aicardi–Goutières syndrome: clues from the RNase H2 knock-out mouse. J Mol Med (Berl) 2013; 91:1235-40. [DOI: 10.1007/s00109-013-1061-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 05/29/2013] [Accepted: 05/30/2013] [Indexed: 01/30/2023]
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185
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Aringer M, Günther C, Lee-Kirsch MA. Innate immune processes in lupus erythematosus. Clin Immunol 2013; 147:216-22. [DOI: 10.1016/j.clim.2012.11.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 11/23/2012] [Accepted: 11/24/2012] [Indexed: 11/30/2022]
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186
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Ghodgaonkar MM, Lazzaro F, Olivera-Pimentel M, Artola-Borán M, Cejka P, Reijns MA, Jackson AP, Plevani P, Muzi-Falconi M, Jiricny J. Ribonucleotides misincorporated into DNA act as strand-discrimination signals in eukaryotic mismatch repair. Mol Cell 2013; 50:323-32. [PMID: 23603115 PMCID: PMC3653069 DOI: 10.1016/j.molcel.2013.03.019] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 01/30/2013] [Accepted: 03/14/2013] [Indexed: 11/28/2022]
Abstract
To improve replication fidelity, mismatch repair (MMR) must detect non-Watson-Crick base pairs and direct their repair to the nascent DNA strand. Eukaryotic MMR in vitro requires pre-existing strand discontinuities for initiation; consequently, it has been postulated that MMR in vivo initiates at Okazaki fragment termini in the lagging strand and at nicks generated in the leading strand by the mismatch-activated MLH1/PMS2 endonuclease. We now show that a single ribonucleotide in the vicinity of a mismatch can act as an initiation site for MMR in human cell extracts and that MMR activation in this system is dependent on RNase H2. As loss of RNase H2 in S.cerevisiae results in a mild MMR defect that is reflected in increased mutagenesis, MMR in vivo might also initiate at RNase H2-generated nicks. We therefore propose that ribonucleotides misincoporated during DNA replication serve as physiological markers of the nascent DNA strand.
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Affiliation(s)
- Medini Manohar Ghodgaonkar
- Institute of Molecular Cancer Research of the University of Zurich and ETH Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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187
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Daddacha W, Noble E, Nguyen LA, Kennedy EM, Kim B. Effect of ribonucleotides embedded in a DNA template on HIV-1 reverse transcription kinetics and fidelity. J Biol Chem 2013; 288:12522-32. [PMID: 23479739 DOI: 10.1074/jbc.m113.458398] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
HIV-1 reverse transcriptase (RT) frequently incorporates ribonucleoside triphosphates (rNTPs) during proviral DNA synthesis, particularly under the limited dNTP conditions found in macrophages. We investigated the mechanistic impacts of an rNMP embedded in DNA templates on HIV-1 RT-mediated DNA synthesis. We observed that the template-embedded rNMP induced pausing of RT and delayed DNA synthesis kinetics at low macrophage dNTP concentrations but not at high T cell dNTP concentrations. Although the binding affinity of RT to the rNMP-containing template-primer was not altered, the dNTP incorporation kinetics of RT were significantly reduced at one nucleotide upstream and downstream of the rNMP site, leading to pause sites. Finally, HIV-1 RT becomes more error-prone at rNMP sites with an elevated mismatch extension capability but not enhanced misinsertion capability. Together these data suggest that rNMPs embedded in DNA templates may influence reverse transcription kinetics and impact viral mutagenesis in macrophages.
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Affiliation(s)
- Waaqo Daddacha
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York 14642, USA
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188
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Chon H, Sparks JL, Rychlik M, Nowotny M, Burgers PM, Crouch RJ, Cerritelli SM. RNase H2 roles in genome integrity revealed by unlinking its activities. Nucleic Acids Res 2013; 41:3130-43. [PMID: 23355612 PMCID: PMC3597693 DOI: 10.1093/nar/gkt027] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Ribonuclease H2 (RNase H2) protects genome integrity by its dual roles of resolving transcription-related R-loops and ribonucleotides incorporated in DNA during replication. To unlink these two functions, we generated a Saccharomyces cerevisiae RNase H2 mutant that can resolve R-loops but cannot cleave single ribonucleotides in DNA. This mutant definitively correlates the 2-5 bp deletions observed in rnh201Δ strains with single rNMPs in DNA. It also establishes a connection between R-loops and Sgs1-mediated replication reinitiation at stalled forks and identifies R-loops uniquely processed by RNase H2. In mouse, deletion of any of the genes coding for RNase H2 results in embryonic lethality, and in humans, RNase H2 hypomorphic mutations cause Aicardi-Goutières syndrome (AGS), a neuroinflammatory disorder. To determine the contribution of R-loops and rNMP in DNA to the defects observed in AGS, we characterized in yeast an AGS-related mutation, which is impaired in processing both substrates, but has sufficient R-loop degradation activity to complement the defects of rnh201Δ sgs1Δ strains. However, this AGS-related mutation accumulates 2-5 bp deletions at a very similar rate as the deletion strain.
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Affiliation(s)
- Hyongi Chon
- Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA, Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA and Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Trojdena Street, 02-109 Warsaw, Poland
| | - Justin L. Sparks
- Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA, Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA and Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Trojdena Street, 02-109 Warsaw, Poland
| | - Monika Rychlik
- Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA, Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA and Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Trojdena Street, 02-109 Warsaw, Poland
| | - Marcin Nowotny
- Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA, Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA and Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Trojdena Street, 02-109 Warsaw, Poland
| | - Peter M. Burgers
- Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA, Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA and Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Trojdena Street, 02-109 Warsaw, Poland
| | - Robert J. Crouch
- Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA, Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA and Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Trojdena Street, 02-109 Warsaw, Poland,*To whom correspondence should be addressed. Tel: +1 301 496 4082; Fax: +1 301 496 0243;
| | - Susana M. Cerritelli
- Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA, Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA and Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Trojdena Street, 02-109 Warsaw, Poland
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189
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White R, Saxty B, Large J, Kettleborough CA, Jackson AP. Identification of small-molecule inhibitors of the ribonuclease H2 enzyme. ACTA ACUST UNITED AC 2013; 18:610-20. [PMID: 23427046 DOI: 10.1177/1087057113476550] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Ribonuclease H2 (RNase H2) is a nuclease that specifically hydrolyzes RNA residues in RNA-DNA hybrids. Mutations in the RNase H2 enzyme complex have been identified in the genetic disorder Aicardi-Goutières syndrome (AGS), which has similarities to the autoimmune disease systemic lupus eryrthrematosis (SLE). The RNase H2 enzyme has also been recently implicated as a key genome surveillance enzyme. Therefore, small-molecule modulators of RNase H2 activity may have utility in therapeutics and as tools to investigate the cellular functions of RNase H2. A fluorescent quench assay, measuring cleavage of an RNA-DNA duplex substrate by recombinant RNase H2, was developed into a high-throughput format and used to screen a 48 560 compound library. A hit validation strategy was subsequently employed, leading to the identification of two novel inhibitor compounds with in vitro nanomolar range inhibition of RNase H2 activity and >100-fold selectivity compared with RNase H type 1. These compounds are the first small-molecule inhibitors of RNase H2 to be reported. They and their derivatives should provide the basis for the development of tool compounds investigating the cellular functions of the RNase H2 enzyme, and, potentially, for pharmacological manipulation of nucleic acid-mediated immune responses.
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Affiliation(s)
- Rachel White
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Edinburgh, UK
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190
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Abstract
Primate immunodeficiency viruses are highly specialized lentiviruses that have evolved to successfully infect and persist for the lifetime of the host. Despite encountering numerous potent antiviral factors, HIVs and SIVs are successful pathogens due to the acquisition of equally potent countermeasures in the form of accessory genes. The accessory gene Vpx encoded by HIV-2 and a subset of SIVs have a profound effect on the ability of lentiviruses to infect non-dividing cells, such as macrophages. Although most virus replication occurs in activated CD4(+) T cells, myeloid lineage cells are natural targets of infection and play a central role in virus transmission, dissemination, and persistence. However, myeloid lineage cells are poorly sensitive to lentiviral infection due partly to the high-level expression of a host protein that regulates nucleic acid metabolism named SAMHD1. Degradation of SAMHD1 is induced by Vpx to eliminate this intrinsic antiviral factor. Importantly, SAMHD1 has also been implicated as a negative regulator of the innate immune response, so the interplay between SAMHD1 and Vpx is likely to have significant consequences for virus replication, persistence, and immune control.
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Affiliation(s)
- Mark Sharkey
- University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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191
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Göksenin AY, Zahurancik W, LeCompte KG, Taggart DJ, Suo Z, Pursell ZF. Human DNA polymerase ε is able to efficiently extend from multiple consecutive ribonucleotides. J Biol Chem 2012; 287:42675-84. [PMID: 23093410 PMCID: PMC3522268 DOI: 10.1074/jbc.m112.422733] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Replicative DNA polymerases (Pols) help to maintain the high fidelity of replication in large part through their strong selectivity against mispaired deoxyribonucleotides. It has recently been demonstrated that several replicative Pols from yeast have surprisingly low selectivity for deoxyribonucleotides over their analogous ribonucleotides. In human cells, ribonucleotides are found in great abundance over deoxyribonucleotides, raising the possibility that ribonucleotides are incorporated in the human genome at significant levels during normal cellular functions. To address this possibility, the ability of human DNA polymerase ϵ to incorporate ribonucleotides was tested. At physiological concentrations of nucleotides, human Pol ϵ readily inserts and extends from incorporated ribonucleotides. Almost half of inserted ribonucleotides escape proofreading by 3′ → 5′ exonuclease-proficient Pol ϵ, indicating that ribonucleotide incorporation by Pol ϵ is likely a significant event in human cells. Human Pol ϵ is also efficient at extending from primers terminating in up to five consecutive ribonucleotides. This efficient extension appears to result from reduced exonuclease activity on primers containing consecutive 3′-terminal ribonucleotides. These biochemical properties suggest that Pol ϵ is a likely source of ribonucleotides in human genomic DNA.
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Affiliation(s)
- A Yasemin Göksenin
- Department of Biochemistry and Molecular Biology and the Tulane Cancer Center, Tulane University School of Medicine, New Orleans, Louisiana 70112, USA
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Stetson DB. Endogenous retroelements and autoimmune disease. Curr Opin Immunol 2012; 24:692-7. [PMID: 23062469 DOI: 10.1016/j.coi.2012.09.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 09/21/2012] [Indexed: 11/18/2022]
Abstract
Innate immune sensors of foreign nucleic acids are essential for antiviral immunity, but these same sensors can cause autoimmune disease through inappropriate detection of self-nucleic acids. The sources of the endogenous RNA and DNA that trigger autoreactive responses include chromatin and ribonucleoproteins that are the targets of autoantibodies in numerous autoimmune diseases, including systemic lupus erythematosus. In this review, I discuss recent data implicating endogenous retroelements-viruses that make up a substantial fraction of our genomes-as an important source of endogenous nucleic acids that can cause autoimmune disease. Understanding this potentially pathologic role for retroelements and the precise mechanisms by which their genomes are sensed and metabolized has important implications for the diagnosis and treatment of numerous autoimmune disorders.
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Affiliation(s)
- Daniel B Stetson
- Department of Immunology, University of Washington, School of Medicine, Seattle, WA 98195, USA.
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Abstract
HIV replication is limited by cellular restriction factors, such as APOBEC and tetherin, which themselves are counteracted by viral proteins. SAMHD1 was recently identified as a novel HIV restriction factor in myeloid cells, and was shown to be blocked by the lentiviral protein Vpx. SAMHD1 limits viral replication through an original mechanism: it hydrolyses intracellular dNTPs in non-cycling cells, thus decreasing the amount of these key substrates, which are required for viral DNA synthesis. In this Progress article, we describe how SAMHD1 regulates the pool of intracellular nucleotides to control HIV replication and the innate immune response.
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