1
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Levanon EY, Cohen-Fultheim R, Eisenberg E. In search of critical dsRNA targets of ADAR1. Trends Genet 2024; 40:250-259. [PMID: 38160061 DOI: 10.1016/j.tig.2023.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 12/04/2023] [Accepted: 12/04/2023] [Indexed: 01/03/2024]
Abstract
Recent studies have underscored the pivotal role of adenosine-to-inosine RNA editing, catalyzed by ADAR1, in suppressing innate immune interferon responses triggered by cellular double-stranded RNA (dsRNA). However, the specific ADAR1 editing targets crucial for this regulatory function remain elusive. We review analyses of transcriptome-wide ADAR1 editing patterns and their evolutionary dynamics, which offer valuable insights into this unresolved query. The growing appreciation of the significance of immunogenic dsRNAs and their editing in inflammatory and autoimmune diseases and cancer calls for a more comprehensive understanding of dsRNA immunogenicity, which may promote our understanding of these diseases and open doors to therapeutic avenues.
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Affiliation(s)
- Erez Y Levanon
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 5290002, Israel.
| | - Roni Cohen-Fultheim
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Eli Eisenberg
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv, University, Tel Aviv 6997801, Israel.
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2
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Estevez-Castro CF, Rodrigues MF, Babarit A, Ferreira FV, de Andrade EG, Marois E, Cogni R, Aguiar ERGR, Marques JT, Olmo RP. Neofunctionalization driven by positive selection led to the retention of the loqs2 gene encoding an Aedes specific dsRNA binding protein. BMC Biol 2024; 22:14. [PMID: 38273313 PMCID: PMC10809485 DOI: 10.1186/s12915-024-01821-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 01/10/2024] [Indexed: 01/27/2024] Open
Abstract
BACKGROUND Mosquito borne viruses, such as dengue, Zika, yellow fever and Chikungunya, cause millions of infections every year. These viruses are mostly transmitted by two urban-adapted mosquito species, Aedes aegypti and Aedes albopictus. Although mechanistic understanding remains largely unknown, Aedes mosquitoes may have unique adaptations that lower the impact of viral infection. Recently, we reported the identification of an Aedes specific double-stranded RNA binding protein (dsRBP), named Loqs2, that is involved in the control of infection by dengue and Zika viruses in mosquitoes. Preliminary analyses suggested that the loqs2 gene is a paralog of loquacious (loqs) and r2d2, two co-factors of the RNA interference (RNAi) pathway, a major antiviral mechanism in insects. RESULTS Here we analyzed the origin and evolution of loqs2. Our data suggest that loqs2 originated from two independent duplications of the first double-stranded RNA binding domain of loqs that occurred before the origin of the Aedes Stegomyia subgenus, around 31 million years ago. We show that the loqs2 gene is evolving under relaxed purifying selection at a faster pace than loqs, with evidence of neofunctionalization driven by positive selection. Accordingly, we observed that Loqs2 is localized mainly in the nucleus, different from R2D2 and both isoforms of Loqs that are cytoplasmic. In contrast to r2d2 and loqs, loqs2 expression is stage- and tissue-specific, restricted mostly to reproductive tissues in adult Ae. aegypti and Ae. albopictus. Transgenic mosquitoes engineered to express loqs2 ubiquitously undergo developmental arrest at larval stages that correlates with massive dysregulation of gene expression without major effects on microRNAs or other endogenous small RNAs, classically associated with RNA interference. CONCLUSIONS Our results uncover the peculiar origin and neofunctionalization of loqs2 driven by positive selection. This study shows an example of unique adaptations in Aedes mosquitoes that could ultimately help explain their effectiveness as virus vectors.
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Affiliation(s)
- Carlos F Estevez-Castro
- Department of Biochemistry and Immunology, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, 31270-901, Brazil
- CNRS UPR9022, Inserm U1257, Université de Strasbourg, 67084, Strasbourg, France
| | - Murillo F Rodrigues
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, 97403-5289, USA
| | - Antinéa Babarit
- CNRS UPR9022, Inserm U1257, Université de Strasbourg, 67084, Strasbourg, France
| | - Flávia V Ferreira
- Department of Biochemistry and Immunology, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, 31270-901, Brazil
| | - Elisa G de Andrade
- Department of Biochemistry and Immunology, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, 31270-901, Brazil
- CNRS UPR9022, Inserm U1257, Université de Strasbourg, 67084, Strasbourg, France
| | - Eric Marois
- CNRS UPR9022, Inserm U1257, Université de Strasbourg, 67084, Strasbourg, France
| | - Rodrigo Cogni
- Department of Ecology, Institute of Biosciences, University of São Paulo, São Paulo, 05508-090, Brazil
| | - Eric R G R Aguiar
- Department of Biological Science, Center of Biotechnology and Genetics, State University of Santa Cruz, Ilhéus, 45662-900, Brazil
| | - João T Marques
- Department of Biochemistry and Immunology, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, 31270-901, Brazil.
- CNRS UPR9022, Inserm U1257, Université de Strasbourg, 67084, Strasbourg, France.
| | - Roenick P Olmo
- Department of Biochemistry and Immunology, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, 31270-901, Brazil.
- CNRS UPR9022, Inserm U1257, Université de Strasbourg, 67084, Strasbourg, France.
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3
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Prince BC, Walsh E, Torres TZB, Rückert C. Recognition of Arboviruses by the Mosquito Immune System. Biomolecules 2023; 13:1159. [PMID: 37509194 PMCID: PMC10376960 DOI: 10.3390/biom13071159] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/12/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023] Open
Abstract
Arthropod-borne viruses (arboviruses) pose a significant threat to both human and animal health worldwide. These viruses are transmitted through the bites of mosquitoes, ticks, sandflies, or biting midges to humans or animals. In humans, arbovirus infection often results in mild flu-like symptoms, but severe disease and death also occur. There are few vaccines available, so control efforts focus on the mosquito population and virus transmission control. One area of research that may enable the development of new strategies to control arbovirus transmission is the field of vector immunology. Arthropod vectors, such as mosquitoes, have coevolved with arboviruses, resulting in a balance of virus replication and vector immune responses. If this balance were disrupted, virus transmission would likely be reduced, either through reduced replication, or even through enhanced replication, resulting in mosquito mortality. The first step in mounting any immune response is to recognize the presence of an invading pathogen. Recent research advances have been made to tease apart the mechanisms of arbovirus detection by mosquitoes. Here, we summarize what is known about arbovirus recognition by the mosquito immune system, try to generate a comprehensive picture, and highlight where there are still gaps in our current understanding.
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Affiliation(s)
- Brian C Prince
- Department of Biochemistry and Molecular Biology, College of Agriculture, Biotechnology & Natural Resources, University of Nevada, Reno, NV 89557, USA
| | - Elizabeth Walsh
- Department of Biochemistry and Molecular Biology, College of Agriculture, Biotechnology & Natural Resources, University of Nevada, Reno, NV 89557, USA
| | - Tran Zen B Torres
- Department of Biochemistry and Molecular Biology, College of Agriculture, Biotechnology & Natural Resources, University of Nevada, Reno, NV 89557, USA
| | - Claudia Rückert
- Department of Biochemistry and Molecular Biology, College of Agriculture, Biotechnology & Natural Resources, University of Nevada, Reno, NV 89557, USA
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4
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de Faria IJS, Aguiar ERGR, Olmo RP, Alves da Silva J, Daeffler L, Carthew RW, Imler JL, Marques JT. Invading viral DNA triggers dsRNA synthesis by RNA polymerase II to activate antiviral RNA interference in Drosophila. Cell Rep 2022; 39:110976. [PMID: 35732126 PMCID: PMC10041815 DOI: 10.1016/j.celrep.2022.110976] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 03/24/2022] [Accepted: 05/26/2022] [Indexed: 11/03/2022] Open
Abstract
dsRNA sensing triggers antiviral responses against RNA and DNA viruses in diverse eukaryotes. In Drosophila, Invertebrate iridescent virus 6 (IIV-6), a large DNA virus, triggers production of small interfering RNAs (siRNAs) by the dsRNA sensor Dicer-2. Here, we show that host RNA polymerase II (RNAPII) bidirectionally transcribes specific AT-rich regions of the IIV-6 DNA genome to generate dsRNA. Both replicative and naked IIV-6 genomes trigger production of dsRNA in Drosophila cells, implying direct sensing of invading DNA. Loquacious-PD, a Dicer-2 co-factor essential for the biogenesis of endogenous siRNAs, is dispensable for processing of IIV-6-derived dsRNAs, which suggests that they are distinct. Consistent with this finding, inhibition of the RNAPII co-factor P-TEFb affects the synthesis of endogenous, but not virus-derived, dsRNA. Altogether, our results suggest that a non-canonical RNAPII complex recognizes invading viral DNA to synthesize virus-derived dsRNA, which activates the antiviral siRNA pathway in Drosophila.
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Affiliation(s)
- Isaque J S de Faria
- Department of Biochemistry and Immunology, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, Brazil; Université de Strasbourg, CNRS UPR9022, INSERM U1257, 67084 Strasbourg, France
| | - Eric R G R Aguiar
- Department of Biochemistry and Immunology, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, Brazil; Department of Biological Science (DCB), Center of Biotechnology and Genetics (CBG), Universidade Estadual de Santa Cruz (UESC), 45662-900 Ilhéus, Brazil
| | - Roenick P Olmo
- Department of Biochemistry and Immunology, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, Brazil; Université de Strasbourg, CNRS UPR9022, INSERM U1257, 67084 Strasbourg, France
| | - Juliana Alves da Silva
- Department of Morphology, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, Brazil
| | - Laurent Daeffler
- Université de Strasbourg, CNRS UPR9022, INSERM U1257, 67084 Strasbourg, France
| | - Richard W Carthew
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA; NSF Simons Center for Quantitative Biology, Northwestern University, Evanston, IL 60208, USA
| | - Jean-Luc Imler
- Université de Strasbourg, CNRS UPR9022, INSERM U1257, 67084 Strasbourg, France
| | - João T Marques
- Department of Biochemistry and Immunology, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, Brazil; Université de Strasbourg, CNRS UPR9022, INSERM U1257, 67084 Strasbourg, France.
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5
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Abstract
RNA viruses are responsible for some of the worst pandemics known to mankind, including outbreaks of Influenza, Ebola, and COVID-19. One major challenge in tackling RNA viruses is the fact they are extremely genetically diverse. Nevertheless, they share common features that include their dependence on host cells for replication, and high mutation rates. We set out to search for shared evolutionary characteristics that may aid in gaining a broader understanding of RNA virus evolution, and constructed a phylogeny-based data set spanning thousands of sequences from diverse single-stranded RNA viruses of animals. Strikingly, we found that the vast majority of these viruses have a skewed nucleotide composition, manifested as adenine rich (A-rich) coding sequences. In order to test whether A-richness is driven by selection or by biased mutation processes, we harnessed the effects of incomplete purifying selection at the tips of virus phylogenies. Our results revealed consistent mutational biases toward U rather than A in genomes of all viruses. In +ssRNA viruses, we found that this bias is compensated by selection against U and selection for A, which leads to A-rich genomes. In -ssRNA viruses, the genomic mutational bias toward U on the negative strand manifests as A-rich coding sequences, on the positive strand. We investigated possible reasons for the advantage of A-rich sequences including weakened RNA secondary structures, codon usage bias, and selection for a particular amino acid composition, and conclude that host immune pressures may have led to similar biases in coding sequence composition across very divergent RNA viruses.
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Affiliation(s)
- Talia Kustin
- The Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Tel Aviv, Israel
| | - Adi Stern
- The Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Tel Aviv, Israel.,Edmond J. Safra Center for Bioinformatics, Tel Aviv University, Tel Aviv, Israel
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6
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Danilenko ED, Belkina AO, Sysoeva GM. Development of Drugs Based on High-Polymeric Double-Stranded RNA for Antiviral and Antitumor Therapy. Biochem Mosc Suppl B Biomed Chem 2019; 13:308-323. [PMID: 32288939 PMCID: PMC7104317 DOI: 10.1134/s1990750819040036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 05/14/2019] [Accepted: 05/16/2019] [Indexed: 12/24/2022]
Abstract
Abstract-The review summarizes literature data on the development of drugs based on natural and synthetic high-polymeric double-stranded RNA (dsRNA), their antiviral, immunoadjuvant, and antitumor properties. Special attention is paid to cell receptors responding to exogenous dsRNA, pathways of dsRNA-dependent antiviral reaction, ability of dsRNA to inhibit growth and induce apoptosis of malignant cells. It has been shown that enhancing the innate immune response with dsRNA can be an effective component in improving methods for treating and preventing infectious and cancer diseases. The further use of dsRNA for the correction of pathological processes of different origin is discussed.
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Affiliation(s)
- E. D. Danilenko
- Institute of Medical Biotechnology, State Research Center of Virology and Biotechnology (SRC VB) “Vector”, Khimzavodskaya ul. 9, 633010 Berdsk, Novosibirsk region Russia
| | - A. O. Belkina
- Institute of Medical Biotechnology, State Research Center of Virology and Biotechnology (SRC VB) “Vector”, Khimzavodskaya ul. 9, 633010 Berdsk, Novosibirsk region Russia
| | - G. M. Sysoeva
- Institute of Medical Biotechnology, State Research Center of Virology and Biotechnology (SRC VB) “Vector”, Khimzavodskaya ul. 9, 633010 Berdsk, Novosibirsk region Russia
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7
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Danilenko ED, Belkina AO, Sysoeva GM. [Development of drugs on the basis of high-polymeric double-stranded RNA for antiviral and antitumor therapy]. Biomed Khim 2019; 65:277-293. [PMID: 31436169 DOI: 10.18097/pbmc20196504277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The review summarizes literature data on the development of drugs based on natural and synthetic high-polymeric double-stranded RNA, and their antiviral, immunoadjuvant and antitumor properties. Special attention is paid to cell receptors responding to exogenous dsRNA, the paths of dsRNA-dependent antiviral reaction, ability of dsRNA to inhibit growth and induce apoptosis ofmalignant cells. It has been shown that enhancing the innate immune response with dsRNA can be an effective component in improving methods for treating and preventing infectious and cancer diseases. The further use of dsRNA for the correction of pathological processes of different origin is discussed.
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Affiliation(s)
- E D Danilenko
- Institute of Medical Biotechnology, State Research Center of Virology and Biotechnology "Vector", Berdsk, Russia
| | - A O Belkina
- Institute of Medical Biotechnology, State Research Center of Virology and Biotechnology "Vector", Berdsk, Russia
| | - G M Sysoeva
- Institute of Medical Biotechnology, State Research Center of Virology and Biotechnology "Vector", Berdsk, Russia
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8
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LaRocca TJ, Mariani A, Watkins LR, Link CD. TDP-43 knockdown causes innate immune activation via protein kinase R in astrocytes. Neurobiol Dis 2019; 132:104514. [PMID: 31229690 DOI: 10.1016/j.nbd.2019.104514] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 04/26/2019] [Accepted: 06/19/2019] [Indexed: 12/13/2022] Open
Abstract
TAR-DNA binding protein 43 (TDP-43) is a multifunctional RNA binding protein directly implicated in the etiology of amyotrophic lateral sclerosis (ALS). Previous studies have demonstrated that loss of TDP-43 function leads to intracellular accumulation of non-coding repetitive element transcripts and double-stranded RNA (dsRNA). These events could cause immune activation and contribute to the neuroinflammation observed in ALS, but this possibility has not been investigated. Here, we knock down TDP-43 in primary rat astrocytes via siRNA, and we use RNA-seq, immunofluorescence, and immunoblotting to show that this results in: 1) accumulation of repetitive element transcripts and dsRNA; and 2) pro-inflammatory gene and protein expression consistent with innate immune signaling and astrocyte activation. We also show that both chemical inhibition and siRNA knockdown of protein kinase R (PKR), a dsRNA-activated kinase implicated in the innate immune response, block the expression of all activation markers assayed. Based on these findings, we suggest that intracellular accumulation of endogenous dsRNA may be a novel and important mechanism underlying the pathogenesis of ALS (and perhaps other neurodegenerative diseases), and that PKR inhibitors may have the potential to prevent reactive astrocytosis in ALS.
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9
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10
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Abstract
The accumulation of nucleic acids in aberrant compartments is a signal of danger: fragments of cytosolic or extracellular self-DNA indicate cellular dysfunctions or disruption, whereas cytosolic fragments of nonself-DNA or RNA indicate infections. Therefore, nucleic acids trigger immunity in mammals and plants. In mammals, endosomal Toll-like receptors (TLRs) sense single-stranded (ss) or double-stranded (ds) RNA or CpG-rich DNA, whereas various cytosolic receptors sense dsDNA. Although a self/nonself discrimination could favor targeted immune responses, no sequence-specific sensing of nucleic acids has been reported for mammals. Specific immune responses to extracellular self-DNA versus DNA from related species were recently reported for plants, but the underlying mechanism remains unknown. The subcellular localization of mammalian receptors can favor self/nonself discrimination based on the localization of DNA fragments. However, autoantibodies and diverse damage-associated molecular patterns (DAMPs) shuttle DNA through membranes, and most of the mammalian receptors share downstream signaling elements such as stimulator of interferon genes (STING) and the master transcription regulators, nuclear factor (NF)-κB, and interferon regulatory factor 3 (IRF3). The resulting type I interferon (IFN) response stimulates innate immunity against multiple threats-from infection to physical injury or endogenous DNA damage-all of which lead to the accumulation of eDNA or cytoplasmatic dsDNA. Therefore, no or only low selective pressures might have favored a strict self/nonself discrimination in nucleic acid sensing. We conclude that the discrimination between self- and nonself-DNA is likely to be less strict-and less important-than assumed originally.
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Affiliation(s)
- Martin Heil
- Departmento de Ingeniería Genética, CINVESTAV-Irapuato, Irapuato, Guanajuato, Mexico.
| | - Isaac Vega-Muñoz
- Departmento de Ingeniería Genética, CINVESTAV-Irapuato, Irapuato, Guanajuato, Mexico
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11
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Monsion B, Incarbone M, Hleibieh K, Poignavent V, Ghannam A, Dunoyer P, Daeffler L, Tilsner J, Ritzenthaler C. Efficient Detection of Long dsRNA in Vitro and in Vivo Using the dsRNA Binding Domain from FHV B2 Protein. Front Plant Sci 2018; 9:70. [PMID: 29449856 PMCID: PMC5799278 DOI: 10.3389/fpls.2018.00070] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 01/12/2018] [Indexed: 05/17/2023]
Abstract
Double-stranded RNA (dsRNA) plays essential functions in many biological processes, including the activation of innate immune responses and RNA interference. dsRNA also represents the genetic entity of some viruses and is a hallmark of infections by positive-sense single-stranded RNA viruses. Methods for detecting dsRNA rely essentially on immunological approaches and their use is often limited to in vitro applications, although recent developments have allowed the visualization of dsRNA in vivo. Here, we report the sensitive and rapid detection of long dsRNA both in vitro and in vivo using the dsRNA binding domain of the B2 protein from Flock house virus. In vitro, we adapted the system for the detection of dsRNA either enzymatically by northwestern blotting or by direct fluorescence labeling on fixed samples. In vivo, we produced stable transgenic Nicotiana benthamiana lines allowing the visualization of dsRNA by fluorescence microscopy. Using these techniques, we were able to discriminate healthy and positive-sense single-stranded RNA virus-infected material in plants and insect cells. In N. benthamiana, our system proved to be very potent for the spatio-temporal visualization of replicative RNA intermediates of a broad range of positive-sense RNA viruses, including high- vs. low-copy number viruses.
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Affiliation(s)
- Baptiste Monsion
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, Université de Strasbourg, Strasbourg, France
| | - Marco Incarbone
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, Université de Strasbourg, Strasbourg, France
| | - Kamal Hleibieh
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, Université de Strasbourg, Strasbourg, France
| | - Vianney Poignavent
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, Université de Strasbourg, Strasbourg, France
| | - Ahmed Ghannam
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, Université de Strasbourg, Strasbourg, France
| | - Patrice Dunoyer
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, Université de Strasbourg, Strasbourg, France
| | - Laurent Daeffler
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Strasbourg, France
| | - Jens Tilsner
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, United Kingdom
- Cell and Molecular Sciences, The James Hutton Institute, Dundee, United Kingdom
| | - Christophe Ritzenthaler
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, Université de Strasbourg, Strasbourg, France
- *Correspondence: Christophe Ritzenthaler
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12
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Zaghloul HAH, Hice R, Arensburger P, Federici BA. Transcriptome Analysis of the Spodoptera frugiperda Ascovirus In Vivo Provides Insights into How Its Apoptosis Inhibitors and Caspase Promote Increased Synthesis of Viral Vesicles and Virion Progeny. J Virol 2017; 91:e00874-17. [PMID: 28956762 PMCID: PMC5686725 DOI: 10.1128/jvi.00874-17] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 08/31/2017] [Indexed: 11/20/2022] Open
Abstract
Ascoviruses are double-stranded DNA (dsDNA) viruses that attack caterpillars and differ from all other viruses by inducing nuclear lysis followed by cleavage of host cells into numerous anucleate vesicles in which virus replication continues as these grow in the blood. Ascoviruses are also unusual in that most encode a caspase or caspase-like proteins. A robust cell line to study the novel molecular biology of ascovirus replication in vitro is lacking. Therefore, we used strand-specific transcriptome sequencing (RNA-Seq) to study transcription in vivo in third instars of Spodoptera frugiperda infected with the type species, Spodoptera frugiperda ascovirus1a (SfAV-1a), sampling transcripts at different time points after infection. We targeted transcription of two types of SfAV-1a genes; first, 44 core genes that occur in several ascovirus species, and second, 26 genes predicted in silico to have metabolic functions likely involved in synthesizing viral vesicle membranes. Gene cluster analysis showed differences in temporal expression of SfAV-1a genes, enabling their assignment to three temporal classes: early, late, and very late. Inhibitors of apoptosis (IAP-like proteins; ORF016, ORF025, and ORF074) were expressed early, whereas its caspase (ORF073) was expressed very late, which correlated with apoptotic events leading to viral vesicle formation. Expression analysis revealed that a Diedel gene homolog (ORF121), the only known "virokine," was highly expressed, implying that this ascovirus protein helps evade innate host immunity. Lastly, single-nucleotide resolution of RNA-Seq data revealed 15 bicistronic and tricistronic messages along the genome, an unusual occurrence for large dsDNA viruses.IMPORTANCE Unlike all other DNA viruses, ascoviruses code for an executioner caspase, apparently involved in a novel cytopathology in which viral replication induces nuclear lysis followed by cell cleavage, yielding numerous large anucleate viral vesicles that continue to produce virions. Our transcriptome analysis of genome expression in vivo by the Spodoptera frugiperda ascovirus shows that inhibitors of apoptosis are expressed first, enabling viral replication to proceed, after which the SfAV-1a caspase is synthesized, leading to viral vesicle synthesis and subsequent extensive production of progeny virions. Moreover, we detected numerous bicistronic and tricistronic mRNA messages in the ascovirus transcriptome, implying that ascoviruses use other noncanonical translational mechanisms, such as internal ribosome entry sites (IRESs). These results provide the first insights into the molecular biology of a unique coordinated gene expression pattern in which cell architecture is markedly modified, more than in any other known eukaryotic virus, to promote viral reproduction and transmission.
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Affiliation(s)
- Heba A H Zaghloul
- Interdepartmental Graduate Program in Microbiology and Institute for Integrative Genome Biology, University of California, Riverside, Riverside, California, USA
- Department of Botany and Microbiology, Faculty of Science, Alexandria University, Alexandria, Egypt
| | - Robert Hice
- Interdepartmental Graduate Program in Microbiology and Institute for Integrative Genome Biology, University of California, Riverside, Riverside, California, USA
| | - Peter Arensburger
- California State Polytechnic University, Pomona, Department of Biological Sciences, Pomona, California, USA
| | - Brian A Federici
- Interdepartmental Graduate Program in Microbiology and Institute for Integrative Genome Biology, University of California, Riverside, Riverside, California, USA
- Department of Entomology, University of California, Riverside, Riverside, California, USA
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13
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Abstract
Endogenous double-stranded RNA (dsRNA) must be intricately regulated in mammals to prevent aberrant activation of host inflammatory pathways by cytosolic dsRNA binding proteins. Here, we define the long, endogenous dsRNA repertoire in mammalian macrophages and monocytes during the inflammatory response to bacterial lipopolysaccharide. Hyperediting by adenosine deaminases that act on RNA (ADAR) enzymes was quantified over time using RNA-seq data from activated mouse macrophages to identify 342 Editing Enriched Regions (EERs), indicative of highly structured dsRNA. Analysis of publicly available data sets for samples of human peripheral blood monocytes resulted in discovery of 3438 EERs in the human transcriptome. Human EERs had predicted secondary structures that were significantly more stable than those of mouse EERs and were located primarily in introns, whereas nearly all mouse EERs were in 3' UTRs. Seventy-four mouse EER-associated genes contained an EER in the orthologous human gene, although nucleotide sequence and position were only rarely conserved. Among these conserved EER-associated genes were several TNF alpha-signaling genes, including Sppl2a and Tnfrsf1b, important for processing and recognition of TNF alpha, respectively. Using publicly available data and experimental validation, we found that a significant proportion of EERs accumulated in the nucleus, a strategy that may prevent aberrant activation of proinflammatory cascades in the cytoplasm. The observation of many ADAR-edited dsRNAs in mammalian immune cells, a subset of which are in orthologous genes of mouse and human, suggests a conserved role for these structured regions.
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Affiliation(s)
- Matthew G Blango
- Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Brenda L Bass
- Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112, USA
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14
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Abstract
Honey bees are significant pollinators of agricultural crops and other important plant species. High annual losses of honey bee colonies in North America and in some parts of Europe have profound ecological and economic implications. Colony losses have been attributed to multiple factors including RNA viruses, thus understanding bee antiviral defense mechanisms may result in the development of strategies that mitigate colony losses. Honey bee antiviral defense mechanisms include RNA-interference, pathogen-associated molecular pattern (PAMP) triggered signal transduction cascades, and reactive oxygen species generation. However, the relative importance of these and other pathways is largely uncharacterized. Herein we review the current understanding of honey bee antiviral defense mechanisms and suggest important avenues for future investigation.
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Affiliation(s)
- Laura M Brutscher
- Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT, USA ; Institute on Ecosystems, Montana State University, Bozeman, MT, USA ; Department of Microbiology and Immunology, Montana State University, Bozeman, MT, USA
| | - Katie F Daughenbaugh
- Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT, USA
| | - Michelle L Flenniken
- Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT, USA ; Institute on Ecosystems, Montana State University, Bozeman, MT, USA ; Department of Microbiology and Immunology, Montana State University, Bozeman, MT, USA
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15
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Abstract
Double-stranded RNA (dsRNA) is arguably the most potent viral trigger of innate immune signaling. Its activity has been recognized for over 5 decades, first as a toxin, then as a central component of the interferon system, as an efficient activator of antiviral responses and an immunomodulator for therapeutic applications. Nucleic acid sensing is the main basis for antiviral defense systems throughout the diverse forms of life from bacteria to plants and animals. Pattern recognition receptors of the host defense system not only sense viral dsRNA as a pathogen-associated molecular pattern in infected cells, but also recognize circulating endogenous dsRNA, a nonmicrobial signal, as a danger-associated molecular pattern, often leading to autoimmunity. Despite the effects of extracellular viral and host dsRNA associated with infection and autoimmunity, respectively, the understanding of cellular mechanisms for its recognition and uptake has only been appreciated in recent years. This review presents an overview of this unique form of nucleic acid, addressing its roles in infection, autoimmunity, and host sensing mechanisms. The goal of this review is to highlight the novel findings with a focus on extracellular recognition and uptake by the cell.
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Affiliation(s)
- Srinivas Nellimarla
- 1 Department of Pathology and Molecular Medicine, McMaster Immunology Research Center, Michael DeGroote Institute for Infectious Disease Research, McMaster University , Hamilton, Ontario, Canada
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16
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Soares ZG, Gonçalves ANA, de Oliveira KPV, Marques JT. Viral RNA recognition by the Drosophila small interfering RNA pathway. Microbes Infect 2014; 16:1013-21. [DOI: 10.1016/j.micinf.2014.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Revised: 08/31/2014] [Accepted: 09/01/2014] [Indexed: 12/24/2022]
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17
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Nicholson AW. Ribonuclease III mechanisms of double-stranded RNA cleavage. Wiley Interdiscip Rev RNA 2013; 5:31-48. [PMID: 24124076 PMCID: PMC3867540 DOI: 10.1002/wrna.1195] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 08/09/2013] [Accepted: 08/10/2013] [Indexed: 12/22/2022]
Abstract
Double-stranded(ds) RNA has diverse roles in gene expression and regulation, host defense, and genome surveillance in bacterial and eukaryotic cells. A central aspect of dsRNA function is its selective recognition and cleavage by members of the ribonuclease III (RNase III) family of divalent-metal-ion-dependent phosphodiesterases. The processing of dsRNA by RNase III family members is an essential step in the maturation and decay of coding and noncoding RNAs, including miRNAs and siRNAs. RNase III, as first purified from Escherichia coli, has served as a biochemically well-characterized prototype, and other bacterial orthologs provided the first structural information. RNase III family members share a unique fold (RNase III domain) that can dimerize to form a structure that binds dsRNA and cleaves phosphodiesters on each strand, providing the characteristic 2 nt, 3′-overhang product ends. Ongoing studies are uncovering the functions of additional domains, including, inter alia, the dsRNA-binding and PAZ domains that cooperate with the RNase III domain to select target sites, regulate activity, confer processivity, and support the recognition of structurally diverse substrates. RNase III enzymes function in multicomponent assemblies that are regulated by diverse inputs, and at least one RNase III-related polypeptide can function as a noncatalytic, dsRNA-binding protein. This review summarizes the current knowledge of the mechanisms of catalysis and target site selection of RNase III family members, and also addresses less well understood aspects of these enzymes and their interactions with dsRNA. WIREs RNA 2014, 5:31–48. doi: 10.1002/wrna.1195
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Affiliation(s)
- Allen W Nicholson
- Department of Biology and Chemistry, College of Science & Technology, Temple University, Philadelphia, PA, USA
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