1
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Zhang Y, Gu X, Li Y, Huang Y, Ju S. Multiple regulatory roles of the transfer RNA-derived small RNAs in cancers. Genes Dis 2024; 11:597-613. [PMID: 37692525 PMCID: PMC10491922 DOI: 10.1016/j.gendis.2023.02.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 02/20/2023] [Indexed: 09/12/2023] Open
Abstract
With the development of sequencing technology, transfer RNA (tRNA)-derived small RNAs (tsRNAs) have received extensive attention as a new type of small noncoding RNAs. Based on the differences in the cleavage sites of nucleases on tRNAs, tsRNAs can be divided into two categories, tRNA halves (tiRNAs) and tRNA-derived fragments (tRFs), each with specific subcellular localizations. Additionally, the biogenesis of tsRNAs is tissue-specific and can be regulated by tRNA modifications. In this review, we first elaborated on the classification and biogenesis of tsRNAs. After summarizing the latest mechanisms of tsRNAs, including transcriptional gene silencing, post-transcriptional gene silencing, nascent RNA silencing, translation regulation, rRNA regulation, and reverse transcription regulation, we explored the representative biological functions of tsRNAs in tumors. Furthermore, this review summarized the clinical value of tsRNAs in cancers, thus providing theoretical support for their potential as novel biomarkers and therapeutic targets.
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Affiliation(s)
- Yu Zhang
- Medical School of Nantong University, Nantong University, Nantong, Jiangsu 226001, China
- Department of Laboratory Medicine, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, China
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, China
| | - Xinliang Gu
- Medical School of Nantong University, Nantong University, Nantong, Jiangsu 226001, China
- Department of Laboratory Medicine, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, China
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, China
| | - Yang Li
- Medical School of Nantong University, Nantong University, Nantong, Jiangsu 226001, China
- Department of Laboratory Medicine, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, China
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, China
| | - Yuejiao Huang
- Medical School of Nantong University, Nantong University, Nantong, Jiangsu 226001, China
- Department of Medical Oncology, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, China
| | - Shaoqing Ju
- Department of Laboratory Medicine, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, China
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2
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Brogli R, Cristodero M, Schneider A, Polacek N. A ribosome-bound tRNA half stimulates mitochondrial translation during stress recovery in Trypanosoma brucei. Cell Rep 2023; 42:113112. [PMID: 37703180 DOI: 10.1016/j.celrep.2023.113112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 07/07/2023] [Accepted: 08/24/2023] [Indexed: 09/15/2023] Open
Abstract
The protozoan parasite Trypanosoma brucei and its disease-causing relatives are among the few organisms that barely regulate the transcription of protein-coding genes. Yet, alterations in its gene expression are essential to survive in different host environments. Recently, tRNA-derived RNAs have been implicated as regulators of many cellular processes within and beyond translation. Previously, we identified the tRNAThr-3'-half (AGU) as a ribosome-associated non-coding RNA able to enhance global translation. Here we report that the tRNAThr-3'-half is generated upon starvation inside the mitochondria. The tRNAThr-3'-half associates with mitochondrial ribosomes and stimulates translation during stress recovery, positively affecting mitochondrial activity and, consequently, cellular energy production capacity. Our results describe an organelle ribosome-associated ncRNA involved in translation regulation to boost the central hub of energy metabolism as an immediate stress recovery response.
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Affiliation(s)
- Rebecca Brogli
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, 3012 Bern, Switzerland; Graduate School for Cellular and Biochemical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Marina Cristodero
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, 3012 Bern, Switzerland.
| | - André Schneider
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Norbert Polacek
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, 3012 Bern, Switzerland.
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3
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Dutta N, Deb I, Sarzynska J, Lahiri A. Inosine and its methyl derivatives: Occurrence, biogenesis, and function in RNA. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2022; 169-170:21-52. [PMID: 35065168 DOI: 10.1016/j.pbiomolbio.2022.01.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 12/11/2021] [Accepted: 01/11/2022] [Indexed: 05/21/2023]
Abstract
Inosine is one of the most common post-transcriptional modifications. Since its discovery, it has been noted for its ability to contribute to non-Watson-Crick interactions within RNA. Rapidly accumulating evidence points to the widespread generation of inosine through hydrolytic deamination of adenosine to inosine by different classes of adenosine deaminases. Three naturally occurring methyl derivatives of inosine, i.e., 1-methylinosine, 2'-O-methylinosine and 1,2'-O-dimethylinosine are currently reported in RNA modification databases. These modifications are expected to lead to changes in the structure, folding, dynamics, stability and functions of RNA. The importance of the modifications is indicated by the strong conservation of the modifying enzymes across organisms. The structure, binding and catalytic mechanism of the adenosine deaminases have been well-studied, but the underlying mechanism of the catalytic reaction is not very clear yet. Here we extensively review the existing data on the occurrence, biogenesis and functions of inosine and its methyl derivatives in RNA. We also included the structural and thermodynamic aspects of these modifications in our review to provide a detailed and integrated discussion on the consequences of A-to-I editing in RNA and the contribution of different structural and thermodynamic studies in understanding its role in RNA. We also highlight the importance of further studies for a better understanding of the mechanisms of the different classes of deamination reactions. Further investigation of the structural and thermodynamic consequences and functions of these modifications in RNA should provide more useful information about their role in different diseases.
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Affiliation(s)
- Nivedita Dutta
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata, 700009, West Bengal, India
| | - Indrajit Deb
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata, 700009, West Bengal, India
| | - Joanna Sarzynska
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Ansuman Lahiri
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata, 700009, West Bengal, India.
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4
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Shiraishi M, Hidaka M, Iwai S. Endonuclease V from the archaeon Thermococcus kodakarensis is an inosine-specific ribonuclease. Biosci Biotechnol Biochem 2022; 86:313-320. [PMID: 34928335 DOI: 10.1093/bbb/zbab219] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 12/11/2021] [Indexed: 11/14/2022]
Abstract
Endonuclease V (EndoV) is an inosine-specific endonuclease which is highly conserved in all domains of life: Bacteria, Archaea, and Eukarya; and, therefore, may play an important role in nucleic acid processes. It is currently thought that bacterial EndoVs are involved in DNA repair, while eukaryotic EndoVs are involved in RNA editing based on the differences in substrate preferences. However, the role of EndoV proteins, particularly in the archaeal domain, is still poorly understood. Here, we explored the biochemical properties of EndoV from the hyperthermophilic archaeon Thermococcus kodakarensis (TkoEndoV). We show that TkoEndoV has a strong preference for RNA over DNA. Further, we synthesized 1-methylinosine-containing RNA that is a simple TΨC loop mimic of archaeal tRNA and found that TkoEndoV discriminates between 1-methylinosine and inosine, and selectively acts on inosine. Our findings suggest a potential role of archaeal EndoV in the regulation of inosine-containing RNA.
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Affiliation(s)
- Miyako Shiraishi
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
| | - Michihi Hidaka
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
| | - Shigenori Iwai
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
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5
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Park Y, Solhtalab M, Thongsomboon W, Aristilde L. Strategies of organic phosphorus recycling by soil bacteria: acquisition, metabolism, and regulation. ENVIRONMENTAL MICROBIOLOGY REPORTS 2022; 14:3-24. [PMID: 35001516 PMCID: PMC9306846 DOI: 10.1111/1758-2229.13040] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 12/07/2021] [Accepted: 12/14/2021] [Indexed: 05/12/2023]
Abstract
Critical to meeting cellular phosphorus (P) demand, soil bacteria deploy a number of strategies to overcome limitation in inorganic P (Pi ) in soils. As a significant contributor to P recycling, soil bacteria secrete extracellular enzymes to degrade organic P (Po ) in soils into the readily bioavailable Pi . In addition, several Po compounds can be transported directly via specific transporters and subsequently enter intracellular metabolic pathways. In this review, we highlight the strategies that soil bacteria employ to recycle Po from the soil environment. We discuss the diversity of extracellular phosphatases in soils, the selectivity of these enzymes towards various Po biomolecules and the influence of the soil environmental conditions on the enzyme's activities. Moreover, we outline the intracellular metabolic pathways for Po biosynthesis and transporter-assisted Po and Pi uptake at different Pi availabilities. We further highlight the regulatory mechanisms that govern the production of phosphatases, the expression of Po transporters and the key metabolic changes in P metabolism in response to environmental Pi availability. Due to the depletion of natural resources for Pi , we propose future studies needed to leverage bacteria-mediated P recycling from the large pools of Po in soils or organic wastes to benefit agricultural productivity.
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Affiliation(s)
- Yeonsoo Park
- Department of Civil and Environmental Engineering, McCormick School of Engineering and Applied ScienceNorthwestern UniversityEvanstonIL60208USA
- Department of Biological and Environmental EngineeringCornell University, Riley‐Robb HallIthacaNY14853USA
| | - Mina Solhtalab
- Department of Civil and Environmental Engineering, McCormick School of Engineering and Applied ScienceNorthwestern UniversityEvanstonIL60208USA
- Department of Biological and Environmental EngineeringCornell University, Riley‐Robb HallIthacaNY14853USA
| | - Wiriya Thongsomboon
- Department of Civil and Environmental Engineering, McCormick School of Engineering and Applied ScienceNorthwestern UniversityEvanstonIL60208USA
- Department of Chemistry, Faculty of ScienceMahasarakham UniversityMahasarakham44150Thailand
| | - Ludmilla Aristilde
- Department of Civil and Environmental Engineering, McCormick School of Engineering and Applied ScienceNorthwestern UniversityEvanstonIL60208USA
- Department of Biological and Environmental EngineeringCornell University, Riley‐Robb HallIthacaNY14853USA
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6
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Krishna S, Raghavan S, DasGupta R, Palakodeti D. tRNA-derived fragments (tRFs): establishing their turf in post-transcriptional gene regulation. Cell Mol Life Sci 2021; 78:2607-2619. [PMID: 33388834 PMCID: PMC11073306 DOI: 10.1007/s00018-020-03720-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 11/02/2020] [Accepted: 11/24/2020] [Indexed: 02/06/2023]
Abstract
Transfer RNA (tRNA)-derived fragments (tRFs) are an emerging class of conserved small non-coding RNAs that play important roles in post-transcriptional gene regulation. High-throughput sequencing of multiple biological samples have identified heterogeneous species of tRFs with distinct functionalities. These small RNAs have garnered a lot of scientific attention due to their ubiquitous expression and versatility in regulating various biological processes. In this review, we highlight our current understanding of tRF biogenesis and their regulatory functions. We summarize the diverse modes of biogenesis through which tRFs are generated and discuss the mechanism through which different tRF species regulate gene expression and the biological implications. Finally, we conceptualize research areas that require focus to strengthen our understanding of the biogenesis and function of tRFs.
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Affiliation(s)
- Srikar Krishna
- Institute for Stem Cell Science and Regenerative Medicine, Bangalore, India
- SASTRA University, Thirumalaisamudram, Thanjavur, India
| | - Srikala Raghavan
- Institute for Stem Cell Science and Regenerative Medicine, Bangalore, India.
| | - Ramanuj DasGupta
- Precision Oncology, Genome Institute of Singapore, Singapore City, Singapore.
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7
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Kong XY, Vik ES, Nawaz MS, Berges N, Dahl TB, Vågbø C, Suganthan R, Segers F, Holm S, Quiles-Jiménez A, Gregersen I, Fladeby C, Aukrust P, Bjørås M, Klungland A, Halvorsen B, Alseth I. Deletion of Endonuclease V suppresses chemically induced hepatocellular carcinoma. Nucleic Acids Res 2020; 48:4463-4479. [PMID: 32083667 PMCID: PMC7192598 DOI: 10.1093/nar/gkaa115] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/08/2020] [Accepted: 02/13/2020] [Indexed: 12/13/2022] Open
Abstract
Endonuclease V (EndoV) is a conserved inosine-specific ribonuclease with unknown biological function. Here, we present the first mouse model lacking EndoV, which is viable without visible abnormalities. We show that endogenous murine EndoV cleaves inosine-containing RNA in vitro, nevertheless a series of experiments fails to link an in vivo function to processing of such transcripts. As inosine levels and adenosine-to-inosine editing often are dysregulated in hepatocellular carcinoma (HCC), we chemically induced HCC in mice. All mice developed liver cancer, however, EndoV−/− tumors were significantly fewer and smaller than wild type tumors. Opposed to human HCC, adenosine deaminase mRNA expression and site-specific editing were unaltered in our model. Loss of EndoV did not affect editing levels in liver tumors, however mRNA expression of a selection of cancer related genes were reduced. Inosines are also found in certain tRNAs and tRNAs are cleaved during stress to produce signaling entities. tRNA fragmentation was dysregulated in EndoV−/− livers and apparently, inosine-independent. We speculate that the inosine-ribonuclease activity of EndoV is disabled in vivo, but RNA binding allowed to promote stabilization of transcripts or recruitment of proteins to fine-tune gene expression. The EndoV−/− tumor suppressive phenotype calls for related studies in human HCC.
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Affiliation(s)
- Xiang Yi Kong
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway
| | - Erik Sebastian Vik
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway
| | - Meh Sameen Nawaz
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway
| | - Natalia Berges
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway
| | - Tuva Børresdatter Dahl
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway.,Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway
| | - Cathrine Vågbø
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Rajikala Suganthan
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway
| | - Filip Segers
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway
| | - Sverre Holm
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway
| | - Ana Quiles-Jiménez
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway.,Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, NO-0317 Oslo, Norway
| | - Ida Gregersen
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway
| | - Cathrine Fladeby
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway
| | - Pål Aukrust
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway.,Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, NO-0317 Oslo, Norway.,Section of Clinical Immunology and Infectious Diseases, Oslo University Hospital, Rikshospitalet, NO-0424 Oslo, Norway
| | - Magnar Bjørås
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway.,Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Arne Klungland
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway.,Department of Molecular Medicine, Institute of Basic Medical Sciences, University ofOslo, NO-0317 Oslo, Norway
| | - Bente Halvorsen
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway.,Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, NO-0317 Oslo, Norway
| | - Ingrun Alseth
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway
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8
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Berges N, Nawaz MS, Børresdatter Dahl T, Hagen L, Bjørås M, Laerdahl JK, Alseth I. Complex alternative splicing of human Endonuclease V mRNA, but evidence for only a single protein isoform. PLoS One 2019; 14:e0225081. [PMID: 31703097 PMCID: PMC6839837 DOI: 10.1371/journal.pone.0225081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 10/27/2019] [Indexed: 12/22/2022] Open
Abstract
Endonuclease V (ENDOV) is a ribonuclease with affinity for inosine which is the deamination product of adenosine. The genomes of most organisms, including human, encode ENDOV homologs, yet knowledge about in vivo functions and gene regulation is sparse. To contribute in this field, we analyzed mRNA and protein expression of human ENDOV (hENDOV). Analyses of public sequence databases revealed numerous hENDOV transcript variants suggesting extensive alternative splicing. Many of the transcripts lacked one or more exons corresponding to conserved regions of the ENDOV core domain, suggesting that these transcripts do not encode for active proteins. Three complete transcripts were found with open reading frames encoding 282, 308 and 309 amino acids, respectively. Recombinant hENDOV 308 and hENDOV 309 share the same cleavage activity as hENDOV 282 which is the variant that has been used in previous studies of hENDOV. However, hENDOV 309 binds inosine-containing RNA with stronger affinity than the other isoforms. Overexpressed GFP-fused isoforms were found in cytoplasm, nucleoli and arsenite induced stress granules in human cells as previously reported for hENDOV 282. RT-qPCR analysis of the 3’-termini showed that hENDOV 308 and hENDOV 309 transcripts are more abundant than hENDOV 282 transcripts in immortalized cell lines, but not in primary cells, suggesting that cells regulate hENDOV mRNA expression. In spite of the presence of all three full-length transcripts, mass spectrometry analyses identified peptides corresponding to the hENDOV 309 isoform only. This result suggests that further studies of human ENDOV should rather encompass the hENDOV 309 isoform.
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Affiliation(s)
- Natalia Berges
- Department of Microbiology, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
| | - Meh Sameen Nawaz
- Department of Microbiology, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
| | - Tuva Børresdatter Dahl
- Department of Microbiology, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
- Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet and Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Lars Hagen
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
- PROMEC Core Facility for Proteomics and Modomics, Norwegian University of Science and Technology and Central Norway Regional Health Authority, Trondheim, Norway
| | - Magnar Bjørås
- Department of Microbiology, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Jon K. Laerdahl
- Department of Microbiology, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
| | - Ingrun Alseth
- Department of Microbiology, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
- * E-mail:
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9
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Yagüe-Capilla M, García-Caballero D, Aguilar-Pereyra F, Castillo-Acosta VM, Ruiz-Pérez LM, Vidal AE, González-Pacanowska D. Base excision repair plays an important role in the protection against nitric oxide- and in vivo-induced DNA damage in Trypanosoma brucei. Free Radic Biol Med 2019; 131:59-71. [PMID: 30472364 DOI: 10.1016/j.freeradbiomed.2018.11.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 10/22/2018] [Accepted: 11/21/2018] [Indexed: 11/17/2022]
Abstract
Uracil-DNA glycosylase (UNG) initiates the base excision repair pathway by excising uracil from DNA. We have previously shown that Trypanosoma brucei cells defective in UNG exhibit reduced infectivity thus demonstrating the relevance of this glycosylase for survival within the mammalian host. In the early steps of the immune response, nitric oxide (NO) is released by phagocytes, which in combination with oxygen radicals produce reactive nitrogen species (RNS). These species can react with DNA generating strand breaks and base modifications including deaminations. Since deaminated cytosines are the main substrate for UNG, we hypothesized that the glycosylase might confer protection towards nitrosative stress. Our work establishes the occurrence of genotoxic damage in Trypanosoma brucei upon exposure to NO in vitro and shows that deficient base excision repair results in increased levels of damage in DNA and a hypermutator phenotype. We also evaluate the incidence of DNA damage during infection in vivo and show that parasites recovered from mice exhibit higher levels of DNA strand breaks, base deamination and repair foci compared to cells cultured in vitro. Notably, the absence of UNG leads to reduced infectivity and enhanced DNA damage also in animal infections. By analysing mRNA and protein levels, we found that surviving UNG-KO trypanosomes highly express tryparedoxin peroxidase involved in trypanothione/tryparedoxin metabolism. These observations suggest that the immune response developed by the host enhances the activation of genes required to counteract oxidative stress and emphasize the importance of DNA repair pathways in the protection to genotoxic and oxidative stress in trypanosomes.
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Affiliation(s)
- Miriam Yagüe-Capilla
- Instituto de Parasitología y Biomedicina "López-Neyra". Consejo Superior de Investigaciones Científicas. Parque Tecnológico de Ciencias de la Salud, Avenida del Conocimiento, 17, 18016 Armilla, Granada, Spain
| | - Daniel García-Caballero
- Instituto de Parasitología y Biomedicina "López-Neyra". Consejo Superior de Investigaciones Científicas. Parque Tecnológico de Ciencias de la Salud, Avenida del Conocimiento, 17, 18016 Armilla, Granada, Spain
| | - Fernando Aguilar-Pereyra
- Instituto de Parasitología y Biomedicina "López-Neyra". Consejo Superior de Investigaciones Científicas. Parque Tecnológico de Ciencias de la Salud, Avenida del Conocimiento, 17, 18016 Armilla, Granada, Spain
| | - Víctor M Castillo-Acosta
- Instituto de Parasitología y Biomedicina "López-Neyra". Consejo Superior de Investigaciones Científicas. Parque Tecnológico de Ciencias de la Salud, Avenida del Conocimiento, 17, 18016 Armilla, Granada, Spain
| | - Luis M Ruiz-Pérez
- Instituto de Parasitología y Biomedicina "López-Neyra". Consejo Superior de Investigaciones Científicas. Parque Tecnológico de Ciencias de la Salud, Avenida del Conocimiento, 17, 18016 Armilla, Granada, Spain
| | - Antonio E Vidal
- Instituto de Parasitología y Biomedicina "López-Neyra". Consejo Superior de Investigaciones Científicas. Parque Tecnológico de Ciencias de la Salud, Avenida del Conocimiento, 17, 18016 Armilla, Granada, Spain
| | - Dolores González-Pacanowska
- Instituto de Parasitología y Biomedicina "López-Neyra". Consejo Superior de Investigaciones Científicas. Parque Tecnológico de Ciencias de la Salud, Avenida del Conocimiento, 17, 18016 Armilla, Granada, Spain.
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