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Liu J, Ito M, Liu L, Nakashima K, Satoh S, Konno A, Suzuki T. Involvement of ribosomal protein L17 and Y-box binding protein 1 in the assembly of hepatitis C virus potentially via their interaction with the 3' untranslated region of the viral genome. J Virol 2024; 98:e0052224. [PMID: 38899899 PMCID: PMC11265288 DOI: 10.1128/jvi.00522-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 05/27/2024] [Indexed: 06/21/2024] Open
Abstract
The 3' untranslated region (3'UTR) of the hepatitis C virus (HCV) RNA genome, which contains a highly conserved 3' region named the 3'X-tail, plays an essential role in RNA replication and promotes viral IRES-dependent translation. Although our previous work has found a cis-acting element for genome encapsidation within 3'X, there is limited information on the involvement of the 3'UTR in particle formation. In this study, proteomic analyses identified host cell proteins that bind to the 3'UTR containing the 3'X region but not to the sequence lacking the 3'X. Further characterization showed that RNA-binding proteins, ribosomal protein L17 (RPL17), and Y-box binding protein 1 (YBX1) facilitate the efficient production of infectious HCV particles in the virus infection cells. Using small interfering RNA (siRNA)-mediated gene silencing in four assays that distinguish between the various stages of the HCV life cycle, RPL17 and YBX1 were found to be most important for particle assembly in the trans-packaging assay with replication-defective subgenomic RNA. In vitro assays showed that RPL17 and YBX1 bind to the 3'UTR RNA and deletion of the 3'X region attenuates their interaction. Knockdown of RPL17 or YBX1 resulted in reducing the amount of HCV RNA co-precipitating with the viral Core protein by RNA immunoprecipitation and increasing the relative distance in space between Core and double-stranded RNA by confocal imaging, suggesting that RPL17 and YBX1 potentially affect HCV RNA-Core interaction, leading to efficient nucleocapsid assembly. These host factors provide new clues to understanding the molecular mechanisms that regulate HCV particle formation. IMPORTANCE Although basic research on the HCV life cycle has progressed significantly over the past two decades, our understanding of the molecular mechanisms that regulate the process of particle formation, in particular encapsidation of the genome or nucleocapsid assembly, has been limited. We present here, for the first time, that two RNA-binding proteins, RPL17 and YBX1, bind to the 3'X in the 3'UTR of the HCV genome, which potentially acts as a packaging signal, and facilitates the viral particle assembly. Our study revealed that RPL17 and YBX1 exert a positive effect on the interaction between HCV RNA and Core protein, suggesting that the presence of both host factors modulate an RNA structure or conformation suitable for packaging the viral genome. These findings help us to elucidate not only the regulatory mechanism of the particle assembly of HCV but also the function of host RNA-binding proteins during viral infection.
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Affiliation(s)
- Jie Liu
- Department of Microbiology and Immunology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Masahiko Ito
- Department of Microbiology and Immunology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Liang Liu
- Department of Microbiology and Immunology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Kenji Nakashima
- Department of Microbiology and Immunology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Shinya Satoh
- Department of Microbiology and Immunology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Alu Konno
- Department of Microbiology and Immunology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Tetsuro Suzuki
- Department of Microbiology and Immunology, Hamamatsu University School of Medicine, Shizuoka, Japan
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2
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Abram QH, Landry BN, Wang AB, Kothe RF, Hauch HC, Sagan SM. The myriad roles of RNA structure in the flavivirus life cycle. RNA Biol 2024; 21:14-30. [PMID: 38797925 PMCID: PMC11135854 DOI: 10.1080/15476286.2024.2357857] [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] [Accepted: 05/16/2024] [Indexed: 05/29/2024] Open
Abstract
As positive-sense RNA viruses, the genomes of flaviviruses serve as the template for all stages of the viral life cycle, including translation, replication, and infectious particle production. Yet, they encode just 10 proteins, suggesting that the structure and dynamics of the viral RNA itself helps shepherd the viral genome through these stages. Herein, we highlight advances in our understanding of flavivirus RNA structural elements through the lens of their impact on the viral life cycle. We highlight how RNA structures impact translation, the switch from translation to replication, negative- and positive-strand RNA synthesis, and virion assembly. Consequently, we describe three major themes regarding the roles of RNA structure in flavivirus infections: 1) providing a layer of specificity; 2) increasing the functional capacity; and 3) providing a mechanism to support genome compaction. While the interactions described herein are specific to flaviviruses, these themes appear to extend more broadly across RNA viruses.
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Affiliation(s)
- Quinn H. Abram
- Department of Biochemistry, McGill University, Montreal, QC, Canada
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Breanna N. Landry
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC, Canada
- Department of Microbiology & Immunology, McGill University, Montreal, QC, Canada
| | - Alex B. Wang
- Department of Biochemistry, McGill University, Montreal, QC, Canada
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Ronja F. Kothe
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Hannah C.H. Hauch
- Department of Microbiology & Immunology, McGill University, Montreal, QC, Canada
| | - Selena M. Sagan
- Department of Biochemistry, McGill University, Montreal, QC, Canada
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC, Canada
- Department of Microbiology & Immunology, McGill University, Montreal, QC, Canada
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3
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Mirzaei R, Karampoor S, Korotkova NL. The emerging role of miRNA-122 in infectious diseases: Mechanisms and potential biomarkers. Pathol Res Pract 2023; 249:154725. [PMID: 37544130 DOI: 10.1016/j.prp.2023.154725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 07/25/2023] [Accepted: 07/26/2023] [Indexed: 08/08/2023]
Abstract
microRNAs (miRNAs) are small, non-coding RNA molecules that play crucial regulatory roles in numerous cellular processes. Recent investigations have highlighted the significant involvement of miRNA-122 (miR-122) in the pathogenesis of infectious diseases caused by diverse pathogens, encompassing viral, bacterial, and parasitic infections. In the context of viral infections, miR-122 exerts regulatory control over viral replication by binding to the viral genome and modulating the host's antiviral response. For instance, in hepatitis B virus (HBV) infection, miR-122 restricts viral replication, while HBV, in turn, suppresses miR-122 expression. Conversely, miR-122 interacts with the hepatitis C virus (HCV) genome, facilitating viral replication. Regarding bacterial infections, miR-122 has been found to regulate host immune responses by influencing inflammatory cytokine production and phagocytosis. In Vibrio anguillarum infections, there is a significant reduction in miR-122 expression, contributing to the pathophysiology of bacterial infections. Toll-like receptor 14 (TLR14) has been identified as a novel target gene of miR-122, affecting inflammatory and immune responses. In the context of parasitic infections, miR-122 plays a crucial role in regulating host lipid metabolism and immune responses. For example, during Leishmania infection, miR-122-containing extracellular vesicles from liver cells are unable to enter infected macrophages, leading to a suppression of the inflammatory response. Furthermore, miR-122 exhibits promise as a potential biomarker for various infectious diseases. Its expression level in body fluids, particularly in serum and plasma, correlates with disease severity and treatment response in patients affected by HCV, HBV, and tuberculosis. This paper also discusses the potential of miR-122 as a biomarker in infectious diseases. In summary, this review provides a comprehensive and insightful overview of the emerging role of miR-122 in infectious diseases, detailing its mechanism of action and potential implications for the development of novel therapeutic strategies.
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Affiliation(s)
- Rasoul Mirzaei
- Venom and Biotherapeutics Molecules Lab, Medical Biotechnology Department, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Sajad Karampoor
- Gastrointestinal and Liver Diseases Research Center, Iran University of Medical Sciences, Tehran, Iran.
| | - Nadezhda Lenoktovna Korotkova
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Russia; Federal State Budgetary Educational Institution of Higher Education "Privolzhsky Research Medical University" of the Ministry of Health of the Russian Federation (FSBEI HE PRMU MOH Russia), Russia
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4
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Panigrahi M, Palmer MA, Wilson JA. Enhanced Virus Translation Enables miR-122-Independent Hepatitis C Virus Propagation. J Virol 2023:e0085821. [PMID: 37338370 PMCID: PMC10373559 DOI: 10.1128/jvi.00858-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 06/05/2023] [Indexed: 06/21/2023] Open
Abstract
The 5' untranslated region (UTR) of the hepatitis C virus (HCV) genome forms RNA structures that regulate virus replication and translation. The region contains an internal ribosomal entry site (IRES) and a 5'-terminal region. Binding of the liver-specific microRNA (miRNA) miR-122 to two binding sites in the 5'-terminal region regulates viral replication, translation, and genome stability and is essential for efficient virus replication, but its precise mechanism of action is still unresolved. A current hypothesis is that miR-122 binding stimulates viral translation by facilitating the viral 5' UTR to form the translationally active HCV IRES RNA structure. While miR-122 is essential for detectable replication of wild-type HCV genomes in cell culture, several viral variants with 5' UTR mutations exhibit low-level replication in the absence of miR-122. We show that HCV mutants capable of replicating independently of miR-122 display an enhanced translation phenotype that correlates with their ability to replicate independently of miR-122. Further, we provide evidence that translation regulation is the major role for miR-122 and show that miR-122-independent HCV replication can be rescued to miR-122-dependent levels by the combined impacts of 5' UTR mutations that stimulate translation and by stabilizing the viral genome by knockdown of host exonucleases and phosphatases that degrade the genome. Finally, we show that HCV mutants capable of replicating independently of miR-122 also replicate independently of other microRNAs generated by the canonical miRNA synthesis pathway. Thus, we provide a model suggesting that translation stimulation and genome stabilization are the primary roles for miR-122 in promoting HCV. IMPORTANCE The unusual and essential role of miR-122 in promoting HCV propagation is incompletely understood. To better understand its role, we have analyzed HCV mutants capable of replicating independently of miR-122. Our data show that the ability of viruses to replicate independently of miR-122 correlates with enhanced virus translation but that genome stabilization is required to restore efficient HCV replication. This suggests that viruses must gain both abilities to escape the need for miR-122 and impacts the possibility that HCV can evolve to replicate outside the liver.
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Affiliation(s)
- Mamata Panigrahi
- Department of Biochemistry, Microbiology and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Michael A Palmer
- Department of Biochemistry, Microbiology and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Joyce A Wilson
- Department of Biochemistry, Microbiology and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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5
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Rheault M, Cousineau SE, Fox DR, Abram QH, Sagan S. Elucidating the distinct contributions of miR-122 in the HCV life cycle reveals insights into virion assembly. Nucleic Acids Res 2023; 51:2447-2463. [PMID: 36807979 PMCID: PMC10018354 DOI: 10.1093/nar/gkad094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 01/20/2023] [Accepted: 02/18/2023] [Indexed: 02/23/2023] Open
Abstract
Efficient hepatitis C virus (HCV) RNA accumulation is dependent upon interactions with the human liver-specific microRNA, miR-122. MiR-122 has at least three roles in the HCV life cycle: it acts as an RNA chaperone, or 'riboswitch', allowing formation of the viral internal ribosomal entry site; it provides genome stability; and promotes viral translation. However, the relative contribution of each role in HCV RNA accumulation remains unclear. Herein, we used point mutations, mutant miRNAs, and HCV luciferase reporter RNAs to isolate each of the roles and evaluate their contribution to the overall impact of miR-122 in the HCV life cycle. Our results suggest that the riboswitch has a minimal contribution in isolation, while genome stability and translational promotion have similar contributions in the establishment phase of infection. However, in the maintenance phase, translational promotion becomes the dominant role. Additionally, we found that an alternative conformation of the 5' untranslated region, termed SLIIalt, is important for efficient virion assembly. Taken together, we have clarified the overall importance of each of the established roles of miR-122 in the HCV life cycle and provided insight into the regulation of the balance between viral RNAs in the translating/replicating pool and those engaged in virion assembly.
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Affiliation(s)
- Marylin Rheault
- Department of Microbiology & Immunology, McGill University, Montréal, Canada
| | - Sophie E Cousineau
- Department of Microbiology & Immunology, McGill University, Montréal, Canada
| | - Danielle R Fox
- Department of Microbiology & Immunology, McGill University, Montréal, Canada
- Department of Physiology, McGill University, Montréal, Canada
| | - Quinn H Abram
- Department of Biochemistry, McGill University, Montréal, Canada
| | - Selena M Sagan
- To whom correspondence should be addressed. Tel: +1 514 398 8110;
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6
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Emanuelson C, Ankenbruck N, Kumbhare R, Thomas M, Connelly C, Baktash Y, Randall G, Deiters A. Transcriptional Inhibition of MicroRNA miR-122 by Small Molecules Reduces Hepatitis C Virus Replication in Liver Cells. J Med Chem 2022; 65:16338-16352. [PMID: 36449366 PMCID: PMC9942140 DOI: 10.1021/acs.jmedchem.2c01141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
MicroRNAs (miRNAs) are noncoding RNA molecules of 22-24 nucleotides that are estimated to regulate thousands of genes in humans, and their dysregulation has been implicated in many diseases. MicroRNA-122 (miR-122) is the most abundant miRNA in the liver and has been linked to the development of hepatocellular carcinoma and hepatitis C virus (HCV) infection. Its role in these diseases renders miR-122 a potential target for small-molecule therapeutics. Here, we report the discovery of a new sulfonamide class of small-molecule miR-122 inhibitors from a high-throughput screen using a luciferase-based reporter assay. Structure-activity relationship (SAR) studies and secondary assays led to the development of potent and selective miR-122 inhibitors. Preliminary mechanism-of-action studies suggest a role in the promoter-specific transcriptional inhibition of miR-122 expression through direct binding to the liver-enriched transcription factor hepatocyte nuclear factor 4α. Importantly, the developed inhibitors significantly reduce HCV replication in human liver cells.
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Affiliation(s)
- Cole Emanuelson
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Nicholas Ankenbruck
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Rohan Kumbhare
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Meryl Thomas
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Colleen Connelly
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Yasmine Baktash
- Department of Microbiology, The University of Chicago, Chicago, Illinois 60637, United States
| | - Glenn Randall
- Department of Microbiology, The University of Chicago, Chicago, Illinois 60637, United States
| | - Alexander Deiters
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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7
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Herod MR, Ward JC, Tuplin A, Harris M, Stonehouse NJ, McCormick CJ. Positive strand RNA viruses differ in the constraints they place on the folding of their negative strand. RNA (NEW YORK, N.Y.) 2022; 28:1359-1376. [PMID: 35918125 PMCID: PMC9479745 DOI: 10.1261/rna.079125.122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 07/22/2022] [Indexed: 06/15/2023]
Abstract
Genome replication of positive strand RNA viruses requires the production of a complementary negative strand RNA that serves as a template for synthesis of more positive strand progeny. Structural RNA elements are important for genome replication, but while they are readily observed in the positive strand, evidence of their existence in the negative strand is more limited. We hypothesized that this was due to viruses differing in their capacity to allow this latter RNA to adopt structural folds. To investigate this, ribozymes were introduced into the negative strand of different viral constructs; the expectation being that if RNA folding occurred, negative strand cleavage and suppression of replication would be seen. Indeed, this was what happened with hepatitis C virus (HCV) and feline calicivirus (FCV) constructs. However, little or no impact was observed for chikungunya virus (CHIKV), human rhinovirus (HRV), hepatitis E virus (HEV), and yellow fever virus (YFV) constructs. Reduced cleavage in the negative strand proved to be due to duplex formation with the positive strand. Interestingly, ribozyme-containing RNAs also remained intact when produced in vitro by the HCV polymerase, again due to duplex formation. Overall, our results show that there are important differences in the conformational constraints imposed on the folding of the negative strand between different positive strand RNA viruses.
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Affiliation(s)
- Morgan R Herod
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Joseph C Ward
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Andrew Tuplin
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Mark Harris
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Nicola J Stonehouse
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Christopher J McCormick
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Sir Henry Wellcome Laboratories, University Hospital Southampton, Southampton SO16 6YD, United Kingdom
- Institute for Life Sciences, University of Southampton SO17 1BJ, United Kingdom
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8
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Panigrahi M, Palmer MA, Wilson JA. MicroRNA-122 Regulation of HCV Infections: Insights from Studies of miR-122-Independent Replication. Pathogens 2022; 11:pathogens11091005. [PMID: 36145436 PMCID: PMC9504723 DOI: 10.3390/pathogens11091005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 08/26/2022] [Accepted: 08/29/2022] [Indexed: 11/18/2022] Open
Abstract
Despite the advancement in antiviral therapy, Hepatitis C remains a global health challenge and one of the leading causes of hepatitis related deaths worldwide. Hepatitis C virus, the causative agent, is a positive strand RNA virus that requires a liver specific microRNA called miR-122 for its replication. Unconventional to the canonical role of miRNAs in translation suppression by binding to 3′Untranslated Region (UTR) of messenger RNAs, miR-122 binds to two sites on the 5′UTR of viral genome and promotes viral propagation. In this review, we describe the unique relationship between the liver specific microRNA and HCV, the current knowledge on the mechanisms by which the virus uses miR-122 to promote the virus life cycle, and how miR-122 impacts viral tropism and pathogenesis. We will also discuss the use of anti-miR-122 therapy and its impact on viral evolution of miR-122-independent replication. This review further provides insight into how viruses manipulate host factors at the initial stage of infection to establish a successful infection.
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9
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miR-122 affects both the initiation and maintenance of Hepatitis C Virus infections. J Virol 2021; 96:e0190321. [PMID: 34908444 DOI: 10.1128/jvi.01903-21] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A liver-specific microRNA, miR-122, anneals to the HCV genomic 5' terminus and is essential for virus replication in cell culture. However, bicistronic HCV replicons and full length RNAs with specific mutations in the 5' UTR can replicate, albeit to low levels, without miR-122. In this study, we have identified that HCV RNAs lacking the structural gene region or having EMCV IRES-regulated translation had reduced requirements for miR-122. In addition, we found that a smaller proportion of cells supported miR-122-independent replication when compared a population of cells supporting miR-122-dependent replication, while viral protein levels per positive cell were similar. Further, the proportion of cells supporting miR-122-independent replication increased with the amount of viral RNA delivered, suggesting that establishment of miR-122-independent replication in a cell is affected by amount of viral RNA delivered. HCV RNAs replicating independent of miR-122 were not affected by supplementation with miR-122, suggesting that miR-122 is not essential for maintenance of a miR-122-independent HCV infection. However, miR-122 supplementation had a small positive impact on miR-122-dependent replication suggesting a minor role in enhancing ongoing virus RNA accumulation. We suggest that miR-122 functions primarily to initiate an HCV infection but has a minor influence on its maintenance, and we present a model in which miR-122 is required for replication complex formation at the beginning of an infection, and also supports new replication complex formation during ongoing infection and after infected cell division. IMPORTANCE: The mechanism by which miR-122 promotes the HCV life cycle is not well understood, and a role in directly promoting genome amplification is still debated. In this study, we have shown that miR-122 increases the rate of viral RNA accumulation and promotes the establishment of an HCV infection in a greater number of cells than in the absence of miR-122. However, we also confirm a minor role in promoting ongoing virus replication and propose a role in the initiation of new replication complexes throughout a virus infection. This study has implications for the use of anti-miR-122 as potential HCV therapy.
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10
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miR-122-based therapies select for three distinct resistance mechanisms based on alterations in RNA structure. Proc Natl Acad Sci U S A 2021; 118:2103671118. [PMID: 34385308 PMCID: PMC8379925 DOI: 10.1073/pnas.2103671118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
MicroRNA (miRNA)–based drugs are quickly taking the clinic by storm. Herein, we analyzed resistance-associated variants (RAVs) to the first miRNA inhibitors to make it to the clinic, namely miR-122 inhibitors for chronic hepatitis C virus (HCV) infection. We uncovered three distinct resistance mechanisms based on unique alterations to the structure of the viral RNA. Specifically, RAVs altered the structure of the viral RNA in a manner that promotes riboswitch activity, genome stability, or positive-strand viral RNA synthesis. Our findings support recent models of miR-122–mediated HCV RNA accumulation and provide mechanism(s) of resistance to antiviral therapy. These early insights into the mechanism(s) of resistance to miRNA-based therapies may be of importance as more miRNA-targeted therapies enter into the clinic. Hepatitis C virus (HCV) is a positive-sense RNA virus that interacts with a liver-specific microRNA called miR-122. miR-122 binds to two sites in the 5′ untranslated region of the viral genome and promotes HCV RNA accumulation. This interaction is important for viral RNA accumulation in cell culture, and miR-122 inhibitors have been shown to be effective at reducing viral titers in chronic HCV-infected patients. Herein, we analyzed resistance-associated variants that were isolated in cell culture or from patients who underwent miR-122 inhibitor–based therapy and discovered three distinct resistance mechanisms all based on changes to the structure of the viral RNA. Specifically, resistance-associated variants promoted riboswitch activity, genome stability, or positive-strand viral RNA synthesis, all in the absence of miR-122. Taken together, these findings provide insight into the mechanism(s) of miR-122–mediated viral RNA accumulation and provide mechanisms of antiviral resistance mediated by changes in RNA structure.
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11
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Tavares RDCA, Mahadeshwar G, Wan H, Huston NC, Pyle AM. The global and local distribution of RNA structure throughout the SARS-CoV-2 genome. J Virol 2021; 95:JVI.02190-20. [PMID: 33268519 PMCID: PMC8092842 DOI: 10.1128/jvi.02190-20] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 11/30/2020] [Indexed: 02/08/2023] Open
Abstract
SARS-CoV-2 is the causative viral agent of COVID-19, the disease at the center of the current global pandemic. While knowledge of highly structured regions is integral for mechanistic insights into the viral infection cycle, very little is known about the location and folding stability of functional elements within the massive, ∼30kb SARS-CoV-2 RNA genome. In this study, we analyze the folding stability of this RNA genome relative to the structural landscape of other well-known viral RNAs. We present an in-silico pipeline to predict regions of high base pair content across long genomes and to pinpoint hotspots of well-defined RNA structures, a method that allows for direct comparisons of RNA structural complexity within the several domains in SARS-CoV-2 genome. We report that the SARS-CoV-2 genomic propensity for stable RNA folding is exceptional among RNA viruses, superseding even that of HCV, one of the most structured viral RNAs in nature. Furthermore, our analysis suggests varying levels of RNA structure across genomic functional regions, with accessory and structural ORFs containing the highest structural density in the viral genome. Finally, we take a step further to examine how individual RNA structures formed by these ORFs are affected by the differences in genomic and subgenomic contexts, which given the technical difficulty of experimentally separating cellular mixtures of sgRNA from gRNA, is a unique advantage of our in-silico pipeline. The resulting findings provide a useful roadmap for planning focused empirical studies of SARS-CoV-2 RNA biology, and a preliminary guide for exploring potential SARS-CoV-2 RNA drug targets.Importance The RNA genome of SARS-CoV-2 is among the largest and most complex viral genomes, and yet its RNA structural features remain relatively unexplored. Since RNA elements guide function in most RNA viruses, and they represent potential drug targets, it is essential to chart the architectural features of SARS-CoV-2 and pinpoint regions that merit focused study. Here we show that RNA folding stability of SARS-CoV-2 genome is exceptional among viral genomes and we develop a method to directly compare levels of predicted secondary structure across SARS-CoV-2 domains. Remarkably, we find that coding regions display the highest structural propensity in the genome, forming motifs that differ between the genomic and subgenomic contexts. Our approach provides an attractive strategy to rapidly screen for candidate structured regions based on base pairing potential and provides a readily interpretable roadmap to guide functional studies of RNA viruses and other pharmacologically relevant RNA transcripts.
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Affiliation(s)
| | - Gandhar Mahadeshwar
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Han Wan
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA
| | - Nicholas C Huston
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Anna Marie Pyle
- Department of Chemistry, Yale University, New Haven, CT 06511, USA
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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12
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Huston NC, Wan H, Strine MS, de Cesaris Araujo Tavares R, Wilen CB, Pyle AM. Comprehensive in vivo secondary structure of the SARS-CoV-2 genome reveals novel regulatory motifs and mechanisms. Mol Cell 2021; 81:584-598.e5. [PMID: 33444546 PMCID: PMC7775661 DOI: 10.1016/j.molcel.2020.12.041] [Citation(s) in RCA: 165] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 11/06/2020] [Accepted: 12/21/2020] [Indexed: 02/07/2023]
Abstract
Severe-acute-respiratory-syndrome-related coronavirus 2 (SARS-CoV-2) is the positive-sense RNA virus that causes coronavirus disease 2019 (COVID-19). The genome of SARS-CoV-2 is unique among viral RNAs in its vast potential to form RNA structures, yet as much as 97% of its 30 kilobases have not been structurally explored. Here, we apply a novel long amplicon strategy to determine the secondary structure of the SARS-CoV-2 RNA genome at single-nucleotide resolution in infected cells. Our in-depth structural analysis reveals networks of well-folded RNA structures throughout Orf1ab and reveals aspects of SARS-CoV-2 genome architecture that distinguish it from other RNA viruses. Evolutionary analysis shows that several features of the SARS-CoV-2 genomic structure are conserved across β-coronaviruses, and we pinpoint regions of well-folded RNA structure that merit downstream functional analysis. The native, secondary structure of SARS-CoV-2 presented here is a roadmap that will facilitate focused studies on the viral life cycle, facilitate primer design, and guide the identification of RNA drug targets against COVID-19.
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Affiliation(s)
- Nicholas C Huston
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Han Wan
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06511, USA
| | - Madison S Strine
- Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT 06510, USA; Department of Immunobiology, Yale School of Medicine, New Haven, CT 06519, USA
| | | | - Craig B Wilen
- Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT 06510, USA; Department of Immunobiology, Yale School of Medicine, New Haven, CT 06519, USA
| | - Anna Marie Pyle
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06511, USA; Department of Chemistry, Yale University, New Haven, CT 06511, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
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13
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Kiani SJ, Ghalejoogh ZY, Samimi-Rad K. Engineered PUF proteins: new flexible toolkits to target the replication of RNA viruses. Future Virol 2021. [PMCID: PMC7808173 DOI: 10.2217/fvl-2020-0134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aim: The RNA recognition code of an RNA-binding protein known as Pumilio/FBF (PUF) protein was reprogrammed in order to provide binding to internal ribosome entry site (IRES) of hepatitis C virus (HCV) genome. Materials & methods: The ability of the modified protein to repress IRES-dependent translation was analyzed by dual-luciferase reporter assay, cell viability assay, cell cytotoxicity assay and anti-HCV assay. Results: The modified protein was able to reduce reporter gene expression (>30%) and HCV viral load (>98%) and reduced HCV-induced cytotoxicity to the level observed in uninfected cells. Conclusion: Our results can set the stage for using modified PUFs for interfering with critical steps such as replication and translation in virus life cycle, especially RNA viruses.
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Affiliation(s)
- Seyed Jalal Kiani
- Department of Virology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Zohreh Yousefi Ghalejoogh
- Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Katayoun Samimi-Rad
- Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
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14
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The Role of the Liver-Specific microRNA, miRNA-122 in the HCV Replication Cycle. Int J Mol Sci 2020; 21:ijms21165677. [PMID: 32784807 PMCID: PMC7460827 DOI: 10.3390/ijms21165677] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/04/2020] [Accepted: 08/05/2020] [Indexed: 02/08/2023] Open
Abstract
Hepatitis C virus (HCV) replication requires annealing of a liver specific microRNA, miR-122 to 2 sites on 5' untranslated region (UTR). While, microRNAs downregulate gene expression by binding to the 3' untranslated region of the target mRNA, in this case, the microRNA anneals to the 5'UTR of the viral genomes and upregulates the viral lifecycle. In this review, we explore the current understandings of the mechanisms by which miR-122 promotes the HCV lifecycle, and its contributions to pathogenesis. Annealing of miR-122 has been reported to (a) stimulate virus translation by promoting the formation of translationally active internal ribosome entry site (IRES) RNA structure, (b) stabilize the genome, and (c) induce viral genomic RNA replication. MiR-122 modulates lipid metabolism and suppresses tumor formation, and sequestration by HCV may influence virus pathogenesis. We also discuss the possible use of miR-122 as a biomarker for chronic hepatitis and as a therapeutic target. Finally, we discuss roles for miR-122 and other microRNAs in promoting other viruses.
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15
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Huston NC, Wan H, de Cesaris Araujo Tavares R, Wilen C, Pyle AM. Comprehensive in-vivo secondary structure of the SARS-CoV-2 genome reveals novel regulatory motifs and mechanisms. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020:2020.07.10.197079. [PMID: 32676598 PMCID: PMC7359520 DOI: 10.1101/2020.07.10.197079] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
SARS-CoV-2 is the positive-sense RNA virus that causes COVID-19, a disease that has triggered a major human health and economic crisis. The genome of SARS-CoV-2 is unique among viral RNAs in its vast potential to form stable RNA structures and yet, as much as 97% of its 30 kilobases have not been structurally explored in the context of a viral infection. Our limited knowledge of SARS-CoV-2 genomic architecture is a fundamental limitation to both our mechanistic understanding of coronavirus life cycle and the development of COVID-19 RNA-based therapeutics. Here, we apply a novel long amplicon strategy to determine for the first time the secondary structure of the SARS-CoV-2 RNA genome probed in infected cells. In addition to the conserved structural motifs at the viral termini, we report new structural features like a conformationally flexible programmed ribosomal frameshifting pseudoknot, and a host of novel RNA structures, each of which highlights the importance of studying viral structures in their native genomic context. Our in-depth structural analysis reveals extensive networks of well-folded RNA structures throughout Orf1ab and reveals new aspects of SARS-CoV-2 genome architecture that distinguish it from other single-stranded, positive-sense RNA viruses. Evolutionary analysis of RNA structures in SARS-CoV-2 shows that several features of its genomic structure are conserved across beta coronaviruses and we pinpoint individual regions of well-folded RNA structure that merit downstream functional analysis. The native, complete secondary structure of SAR-CoV-2 presented here is a roadmap that will facilitate focused studies on mechanisms of replication, translation and packaging, and guide the identification of new RNA drug targets against COVID-19.
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Affiliation(s)
- Nicholas C. Huston
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Han Wan
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA
| | | | - Craig Wilen
- Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT, USA
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
| | - Anna Marie Pyle
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA
- Department of Chemistry, Yale University, New Haven, CT, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
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16
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Ono C, Fukuhara T, Li S, Wang J, Sato A, Izumi T, Fauzyah Y, Yamamoto T, Morioka Y, Dokholyan NV, Standley DM, Matsuura Y. Various miRNAs compensate the role of miR-122 on HCV replication. PLoS Pathog 2020; 16:e1008308. [PMID: 32574204 PMCID: PMC7337399 DOI: 10.1371/journal.ppat.1008308] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 07/06/2020] [Accepted: 05/18/2020] [Indexed: 02/07/2023] Open
Abstract
One of the determinants for tissue tropism of hepatitis C virus (HCV) is miR-122, a liver-specific microRNA. Recently, it has been reported that interaction of miR-122 to HCV RNA induces a conformational change of the 5'UTR internal ribosome entry site (IRES) structure to form stem-loop II structure (SLII) and hijack of translating 80S ribosome through the binding of SLIII to 40S subunit, which leads to efficient translation. On the other hand, low levels of HCV-RNA replication have also been detected in some non-hepatic cells; however, the details of extrahepatic replication remain unknown. These observations suggest the possibility that miRNAs other than miR-122 can support efficient replication of HCV-RNA in non-hepatic cells. Here, we identified a number of such miRNAs and show that they could be divided into two groups: those that bind HCV-RNA at two locations (miR-122 binding sites I and II), in a manner similar to miR-122 (miR-122-like), and those that target a single site that bridges sites I and II and masking both G28 and C29 in the 5'UTR (non-miR-122-like). Although the enhancing activity of these non-hepatic miRNAs were lower than those of miR-122, substantial expression was detected in various normal tissues. Furthermore, structural modeling indicated that both miR-122-like and non-miR-122-like miRNAs not only can facilitate the formation of an HCV IRES SLII but also can stabilize IRES 3D structure in order to facilitate binding of SLIII to the ribosome. Together, these results suggest that HCV facilitates miR-122-independent replication in non-hepatic cells through recruitment of miRNAs other than miR-122. And our findings can provide a more detailed mechanism of miR-122-dependent enhancement of HCV-RNA translation by focusing on IRES tertiary structure.
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Affiliation(s)
- Chikako Ono
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Takasuke Fukuhara
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Songling Li
- Department of Genome Informatics, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Jian Wang
- Department of Pharmacology, Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Asuka Sato
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Takuma Izumi
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Yuzy Fauzyah
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Takuya Yamamoto
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Yuhei Morioka
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Nikolay V. Dokholyan
- Department of Pharmacology, Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
- Department of Biochemistry & Molecular Biology, Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Daron M. Standley
- Department of Genome Informatics, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Yoshiharu Matsuura
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
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17
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Hepatitis C Virus Translation Regulation. Int J Mol Sci 2020; 21:ijms21072328. [PMID: 32230899 PMCID: PMC7178104 DOI: 10.3390/ijms21072328] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 03/18/2020] [Accepted: 03/25/2020] [Indexed: 12/12/2022] Open
Abstract
Translation of the hepatitis C virus (HCV) RNA genome is regulated by the internal ribosome entry site (IRES), located in the 5’-untranslated region (5′UTR) and part of the core protein coding sequence, and by the 3′UTR. The 5′UTR has some highly conserved structural regions, while others can assume different conformations. The IRES can bind to the ribosomal 40S subunit with high affinity without any other factors. Nevertheless, IRES activity is modulated by additional cis sequences in the viral genome, including the 3′UTR and the cis-acting replication element (CRE). Canonical translation initiation factors (eIFs) are involved in HCV translation initiation, including eIF3, eIF2, eIF1A, eIF5, and eIF5B. Alternatively, under stress conditions and limited eIF2-Met-tRNAiMet availability, alternative initiation factors such as eIF2D, eIF2A, and eIF5B can substitute for eIF2 to allow HCV translation even when cellular mRNA translation is downregulated. In addition, several IRES trans-acting factors (ITAFs) modulate IRES activity by building large networks of RNA-protein and protein–protein interactions, also connecting 5′- and 3′-ends of the viral RNA. Moreover, some ITAFs can act as RNA chaperones that help to position the viral AUG start codon in the ribosomal 40S subunit entry channel. Finally, the liver-specific microRNA-122 (miR-122) stimulates HCV IRES-dependent translation, most likely by stabilizing a certain structure of the IRES that is required for initiation.
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18
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Tabata K, Neufeldt CJ, Bartenschlager R. Hepatitis C Virus Replication. Cold Spring Harb Perspect Med 2020; 10:cshperspect.a037093. [PMID: 31570388 DOI: 10.1101/cshperspect.a037093] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Replication and amplification of the viral genome is a key process for all viruses. For hepatitis C virus (HCV), a positive-strand RNA virus, amplification of the viral genome requires the synthesis of a negative-sense RNA template, which is in turn used for the production of new genomic RNA. This process is governed by numerous proteins, both host and viral, as well as distinct lipids and specific RNA elements within the positive- and negative-strand RNAs. Moreover, this process requires specific changes to host cell ultrastructure to create microenvironments conducive to viral replication. This review will focus on describing the processes and factors involved in facilitating or regulating HCV genome replication.
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Affiliation(s)
- Keisuke Tabata
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Christopher J Neufeldt
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany.,Division of Virus-Associated Carcinogenesis, German Cancer Research Center, 69120 Heidelberg, Germany.,German Center for Infection Research, Heidelberg Partner Site, 69120 Heidelberg, Germany
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19
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Hepatitis C Virus Downregulates Core Subunits of Oxidative Phosphorylation, Reminiscent of the Warburg Effect in Cancer Cells. Cells 2019; 8:cells8111410. [PMID: 31717433 PMCID: PMC6912740 DOI: 10.3390/cells8111410] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 11/05/2019] [Accepted: 11/06/2019] [Indexed: 02/08/2023] Open
Abstract
Hepatitis C Virus (HCV) mainly infects liver hepatocytes and replicates its single-stranded plus strand RNA genome exclusively in the cytoplasm. Viral proteins and RNA interfere with the host cell immune response, allowing the virus to continue replication. Therefore, in about 70% of cases, the viral infection cannot be cleared by the immune system, but a chronic infection is established, often resulting in liver fibrosis, cirrhosis and hepatocellular carcinoma (HCC). Induction of cancer in the host cells can be regarded to provide further advantages for ongoing virus replication. One adaptation in cancer cells is the enhancement of cellular carbohydrate flux in glycolysis with a reduction of the activity of the citric acid cycle and aerobic oxidative phosphorylation. To this end, HCV downregulates the expression of mitochondrial oxidative phosphorylation complex core subunits quite early after infection. This so-called aerobic glycolysis is known as the “Warburg Effect” and serves to provide more anabolic metabolites upstream of the citric acid cycle, such as amino acids, pentoses and NADPH for cancer cell growth. In addition, HCV deregulates signaling pathways like those of TNF-β and MAPK by direct and indirect mechanisms, which can lead to fibrosis and HCC.
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20
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Evidence for Internal Initiation of RNA Synthesis by the Hepatitis C Virus RNA-Dependent RNA Polymerase NS5B In Cellulo. J Virol 2019; 93:JVI.00525-19. [PMID: 31315989 DOI: 10.1128/jvi.00525-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 07/07/2019] [Indexed: 12/11/2022] Open
Abstract
Initiation of RNA synthesis by the hepatitis C virus (HCV) RNA-dependent RNA polymerase (RdRp) NS5B has been extensively studied in vitro and in cellulo Intracellular replication is thought to rely exclusively on terminal de novo initiation, as it conserves all genetic information of the genome. In vitro, however, additional modes of initiation have been observed. In this study, we aimed to clarify whether the intracellular environment allows for internal initiation of RNA replication by the HCV replicase. We used a dual luciferase replicon harboring a terminal and an internal copy of the viral genomic 5' untranslated region, which was anticipated to support noncanonical initiation. Indeed, a shorter RNA species was detected by Northern blotting with low frequency, depending on the length and sequence composition upstream of the internal initiation site. By introducing mutations at either site, we furthermore established that internal and terminal initiation shared identical sequence requirements. Importantly, lethal point mutations at the terminal site resulted exclusively in truncated replicons. In contrast, the same mutations at the internal site abrogated internal initiation, suggesting a competitive selection of initiation sites, rather than recombination or template-switching events. In conclusion, our data indicate that the HCV replicase is capable of internal initiation in its natural environment, although functional replication likely requires only terminal initiation. Since many other positive-strand RNA viruses generate subgenomic messenger RNAs during their replication cycle, we surmise that their capability for internal initiation is a common and conserved feature of viral RdRps.IMPORTANCE Many aspects of viral RNA replication of hepatitis C virus (HCV) are still poorly understood. The process of RNA synthesis is driven by the RNA-dependent RNA polymerase (RdRp) NS5B. Most mechanistic studies on NS5B so far were performed with in vitro systems using isolated recombinant polymerase. In this study, we present a replicon model, which allows the intracellular assessment of noncanonical modes of initiation by the full HCV replicase. Our results add to the understanding of the biochemical processes underlying initiation of RNA synthesis by NS5B by the discovery of internal initiation in cellulo Moreover, they validate observations made in vitro, showing that the viral polymerase acts very similarly in isolation and in complex with other viral and host proteins. Finally, these observations provide clues about the evolution of RdRps of positive-strand RNA viruses, which might contain the intrinsic ability to initiate internally.
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21
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Amador-Cañizares Y, Panigrahi M, Huys A, Kunden RD, Adams HM, Schinold MJ, Wilson JA. miR-122, small RNA annealing and sequence mutations alter the predicted structure of the Hepatitis C virus 5' UTR RNA to stabilize and promote viral RNA accumulation. Nucleic Acids Res 2019; 46:9776-9792. [PMID: 30053137 PMCID: PMC6182169 DOI: 10.1093/nar/gky662] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 07/11/2018] [Indexed: 01/01/2023] Open
Abstract
Annealing of the liver-specific microRNA, miR-122, to the Hepatitis C virus (HCV) 5′ UTR is required for efficient virus replication. By using siRNAs to pressure escape mutations, 30 replication-competent HCV genomes having nucleotide changes in the conserved 5′ untranslated region (UTR) were identified. In silico analysis predicted that miR-122 annealing induces canonical HCV genomic 5′ UTR RNA folding, and mutant 5′ UTR sequences that promoted miR-122-independent HCV replication favored the formation of the canonical RNA structure, even in the absence of miR-122. Additionally, some mutant viruses adapted to use the siRNA as a miR-122-mimic. We further demonstrate that small RNAs that anneal with perfect complementarity to the 5′ UTR stabilize and promote HCV genome accumulation. Thus, HCV genome stabilization and life-cycle promotion does not require the specific annealing pattern demonstrated for miR-122 nor 5′ end annealing or 3′ overhanging nucleotides. Replication promotion by perfect-match siRNAs was observed in Ago2 knockout cells revealing that other Ago isoforms can support HCV replication. At last, we present a model for miR-122 promotion of the HCV life cycle in which miRNA annealing to the 5′ UTR, in conjunction with any Ago isoform, modifies the 5′ UTR structure to stabilize the viral genome and promote HCV RNA accumulation.
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Affiliation(s)
- Yalena Amador-Cañizares
- Department of Microbiology & Immunology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
| | - Mamata Panigrahi
- Department of Microbiology & Immunology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
| | - Adam Huys
- Department of Microbiology & Immunology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
| | - Rasika D Kunden
- Department of Microbiology & Immunology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
| | - Halim M Adams
- Department of Microbiology & Immunology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
| | - Michael J Schinold
- Department of Microbiology & Immunology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
| | - Joyce A Wilson
- Department of Microbiology & Immunology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
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22
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Sam68 Promotes Hepatitis C Virus Replication by Interaction with Stem-Loop 2 of Viral 5' Untranslated Region. J Virol 2019; 93:JVI.00693-19. [PMID: 31068419 DOI: 10.1128/jvi.00693-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 04/26/2019] [Indexed: 12/12/2022] Open
Abstract
The Src-associated in mitosis 68-kDa (Sam68) protein is a highly conserved nuclear protein and is involved in a series of cellular processes, including transcription and signal transduction. Sam68 is comprised of 443 amino acids and contains an RGG box domain, a KH domain, and a tyrosine-rich domain. Its role in hepatitis C virus (HCV) replication is unknown. Here, we find that Sam68 promotes HCV replication without affecting viral translation. The RNA immunoprecipitation experiments show that the positive strand of HCV RNA interacts with Sam68. HCV infection triggers the translocation of the Sam68 protein from the nucleus to the cytoplasm, where it interacts with the HCV genome. Further study shows that the region of Sam68 spanning amino acids 1 to 157 is the pivotal domain to interact with the stem-loop 2 of the HCV 5' untranslated region (5' UTR) and is responsible for the enhancement of HCV replication. These data suggested that Sam68 may serve as a proviral factor of HCV to facilitate viral replication through interaction with the viral genome.IMPORTANCE Hepatitis C virus (HCV) is a member of the Flaviviridae family, and its infection causes chronic hepatitis, liver cirrhosis, and even hepatocellular carcinoma. No vaccine is available. Many host factors may be implicated in the pathogenesis of HCV-related diseases. This study discloses a new host factor that binds to the HCV 5' UTR and promotes HCV replication. Sam68 may play an important role in HCV-related diseases, and further investigation is highly encouraged to explore its specific actions in HCV pathogenesis.
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23
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Chahal J, Gebert LF, Gan HH, Camacho E, Gunsalus KC, MacRae IJ, Sagan SM. miR-122 and Ago interactions with the HCV genome alter the structure of the viral 5' terminus. Nucleic Acids Res 2019; 47:5307-5324. [PMID: 30941417 PMCID: PMC6547439 DOI: 10.1093/nar/gkz194] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 03/11/2019] [Accepted: 03/20/2019] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV) is a positive-sense RNA virus that interacts with the liver-specific microRNA, miR-122. miR-122 binds to two sites in the 5' untranslated region (UTR) and this interaction promotes HCV RNA accumulation, although the precise role of miR-122 in the HCV life cycle remains unclear. Using biophysical analyses and Selective 2' Hydroxyl Acylation analyzed by Primer Extension (SHAPE) we investigated miR-122 interactions with the 5' UTR. Our data suggests that miR-122 binding results in alteration of nucleotides 1-117 to suppress an alternative secondary structure and promote functional internal ribosomal entry site (IRES) formation. Furthermore, we demonstrate that two hAgo2:miR-122 complexes are able to bind to the HCV 5' terminus simultaneously and SHAPE analyses revealed further alterations to the structure of the 5' UTR to accommodate these complexes. Finally, we present a computational model of the hAgo2:miR-122:HCV RNA complex at the 5' terminus of the viral genome as well as hAgo2:miR-122 interactions with the IRES-40S complex that suggest hAgo2 is likely to form additional interactions with SLII which may further stabilize the HCV IRES. Taken together, our results support a model whereby hAgo2:miR-122 complexes alter the structure of the viral 5' terminus and promote formation of the HCV IRES.
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Affiliation(s)
- Jasmin Chahal
- Department of Microbiology & Immunology, McGill University, Montréal, QC H3G 1Y6, Canada
| | - Luca F R Gebert
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Hin Hark Gan
- Center for Genomics and Systems Biology, Department of Biology, New York University, 12 Waverly Place, New York, NY 10003, USA
| | - Edna Camacho
- Department of Biochemistry, McGill University, Montréal, QC H3G 1Y6, Canada
| | - Kristin C Gunsalus
- Center for Genomics and Systems Biology, Department of Biology, New York University, 12 Waverly Place, New York, NY 10003, USA
- Division of Biology, New York University Abu Dhabi, Abu Dhabi, UAE
| | - Ian J MacRae
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Selena M Sagan
- Department of Microbiology & Immunology, McGill University, Montréal, QC H3G 1Y6, Canada
- Department of Biochemistry, McGill University, Montréal, QC H3G 1Y6, Canada
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24
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Mata M, Neben S, Majzoub K, Carette J, Ramanathan M, Khavari PA, Sarnow P. Impact of a patient-derived hepatitis C viral RNA genome with a mutated microRNA binding site. PLoS Pathog 2019; 15:e1007467. [PMID: 31075158 PMCID: PMC6530871 DOI: 10.1371/journal.ppat.1007467] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 05/22/2019] [Accepted: 04/15/2019] [Indexed: 02/06/2023] Open
Abstract
Hepatitis C virus (HCV) depends on liver-specific microRNA miR-122 for efficient viral RNA amplification in liver cells. This microRNA interacts with two different conserved sites at the very 5’ end of the viral RNA, enhancing miR-122 stability and promoting replication of the viral RNA. Treatment of HCV patients with oligonucleotides that sequester miR-122 resulted in profound loss of viral RNA in phase II clinical trials. However, some patients accumulated in their sera a viral RNA genome that contained a single cytidine to uridine mutation at the third nucleotide from the 5’ genomic end. It is shown here that this C3U variant indeed displayed higher rates of replication than that of wild-type HCV when miR-122 abundance is low in liver cells. However, when miR-122 abundance is high, binding of miR-122 to site 1, most proximal to the 5’ end in the C3U variant RNA, is impaired without disrupting the binding of miR-122 to site 2. As a result, C3U RNA displays a much lower rate of replication than wild-type mRNA when miR-122 abundance is high in the liver. This phenotype was accompanied by binding of a different set of cellular proteins to the 5’ end of the C3U RNA genome. In particular, binding of RNA helicase DDX6 was important for displaying the C3U RNA replication phenotype in liver cells. These findings suggest that sequestration of miR-122 leads to a resistance-associated mutation that has only been observed in treated patients so far, and raises the question about the function of the C3U variant in the peripheral blood. With the advent of potent direct-acting antivirals (DAA), hepatitis C virus (HCV) can now be eliminated from the majority of patients, using multidrug therapy with DAAs. However, such DAAs are not available for the treatment of most RNA virus infections. The main problem is the high error rate by which RNA-dependent RNA polymerases copy viral RNA genomes, allowing the selection of mutations that are resistant to DAAs. Thus, targeting host-encoded functions that are essential for growth of the virus but not for the host cell offer promising, novel approaches. HCV needs host-encoded microRNA miR-122 for its viral RNA replication in the liver, and depletion of miR-122 in HCV patients results in loss of viral RNA. This study shows that a single-nucleotide mutation in HCV allows viral RNA amplification when miR-122 abundances are low, concomitant with changes in its tropism.
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Affiliation(s)
- Miguel Mata
- Department of Microbiology & Immunology, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Steven Neben
- Regulus Therapeutics, San Diego, CA, United States of America
| | - Karim Majzoub
- Department of Microbiology & Immunology, Stanford University School of Medicine, Stanford, CA, United States of America.,INSERM U1110, Institute of Viral and Liver Disease, University of Strasbourg, France
| | - Jan Carette
- Department of Microbiology & Immunology, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Muthukumar Ramanathan
- Program in Epithelial Biology, Stanford University School of Medicine, Stanford, CA, United States of America; Veterans Affairs Palo Alto Healthcare System, Palo Alto, CA, United States of America
| | - Paul A Khavari
- Program in Epithelial Biology, Stanford University School of Medicine, Stanford, CA, United States of America; Veterans Affairs Palo Alto Healthcare System, Palo Alto, CA, United States of America
| | - Peter Sarnow
- Department of Microbiology & Immunology, Stanford University School of Medicine, Stanford, CA, United States of America
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25
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Desirò D, Hölzer M, Ibrahim B, Marz M. SilentMutations (SIM): A tool for analyzing long-range RNA-RNA interactions in viral genomes and structured RNAs. Virus Res 2019; 260:135-141. [PMID: 30439394 PMCID: PMC7172452 DOI: 10.1016/j.virusres.2018.11.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 10/30/2018] [Accepted: 11/09/2018] [Indexed: 01/28/2023]
Abstract
We developed a tool to analyze the effect of multiple point mutations on the secondary structures of two interacting viral RNAs. Our tool simulates destructive and compensatory mutants of two key regions from a single-stranded RNA. The simulated mutants can be utilized for the combinatorial in vitro analysis of RNA–RNA interactions. We predicted potential mutants for in vitro validation experiments of influenza A virus and hepatitis C virus interactions.
A single nucleotide change in the coding region can alter the amino acid sequence of a protein. In consequence, natural or artificial sequence changes in viral RNAs may have various effects not only on protein stability, function and structure but also on viral replication. In recent decades, several tools have been developed to predict the effect of mutations in structured RNAs such as viral genomes or non-coding RNAs. Some tools use multiple point mutations and also take coding regions into account. However, none of these tools was designed to specifically simulate the effect of mutations on viral long-range interactions. Here, we developed SilentMutations (SIM), an easy-to-use tool to analyze the effect of multiple point mutations on the secondary structures of two interacting viral RNAs. The tool can simulate disruptive and compensatory mutants of two interacting single-stranded RNAs. This allows a fast and accurate assessment of key regions potentially involved in functional long-range RNA–RNA interactions and will eventually help virologists and RNA-experts to design appropriate experiments. SIM only requires two interacting single-stranded RNA regions as input. The output is a plain text file containing the most promising mutants and a graphical representation of all interactions. We applied our tool on two experimentally validated influenza A virus and hepatitis C virus interactions and we were able to predict potential double mutants for in vitro validation experiments. The source code and documentation of SIM are freely available at github.com/desiro/silentMutations.
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Affiliation(s)
- Daniel Desirò
- European Virus Bioinformatics Center, Jena, Germany; RNA Bioinformatics and High-Throughput Analysis, Friedrich Schiller University, Jena, Germany
| | - Martin Hölzer
- European Virus Bioinformatics Center, Jena, Germany; RNA Bioinformatics and High-Throughput Analysis, Friedrich Schiller University, Jena, Germany
| | - Bashar Ibrahim
- European Virus Bioinformatics Center, Jena, Germany; Chair of Bioinformatics, Matthias Schleiden Institute, Friedrich Schiller University, Jena, Germany
| | - Manja Marz
- European Virus Bioinformatics Center, Jena, Germany; RNA Bioinformatics and High-Throughput Analysis, Friedrich Schiller University, Jena, Germany; Leibniz Institute for Age Research-Fritz Lipmann Institute, Jena, Germany.
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26
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Lozano G, Francisco-Velilla R, Martinez-Salas E. Deconstructing internal ribosome entry site elements: an update of structural motifs and functional divergences. Open Biol 2018; 8:rsob.180155. [PMID: 30487301 PMCID: PMC6282068 DOI: 10.1098/rsob.180155] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 10/30/2018] [Indexed: 12/16/2022] Open
Abstract
Beyond the general cap-dependent translation initiation, eukaryotic organisms use alternative mechanisms to initiate protein synthesis. Internal ribosome entry site (IRES) elements are cis-acting RNA regions that promote internal initiation of translation using a cap-independent mechanism. However, their lack of primary sequence and secondary RNA structure conservation, as well as the diversity of host factor requirement to recruit the ribosomal subunits, suggest distinct types of IRES elements. In spite of this heterogeneity, conserved motifs preserve sequences impacting on RNA structure and RNA–protein interactions important for IRES-driven translation. This conservation brings the question of whether IRES elements could consist of basic building blocks, which upon evolutionary selection result in functional elements with different properties. Although RNA-binding proteins (RBPs) perform a crucial role in the assembly of ribonucleoprotein complexes, the versatility and plasticity of RNA molecules, together with their high flexibility and dynamism, determines formation of macromolecular complexes in response to different signals. These properties rely on the presence of short RNA motifs, which operate as modular entities, and suggest that decomposition of IRES elements in short modules could help to understand the different mechanisms driven by these regulatory elements. Here we will review evidence suggesting that model IRES elements consist of the combination of short modules, providing sites of interaction for ribosome subunits, eIFs and RBPs, with implications for definition of criteria to identify novel IRES-like elements genome wide.
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Affiliation(s)
- Gloria Lozano
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Nicolás Cabrera 1, 28049 Madrid, Spain
| | - Rosario Francisco-Velilla
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Nicolás Cabrera 1, 28049 Madrid, Spain
| | - Encarnacion Martinez-Salas
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Nicolás Cabrera 1, 28049 Madrid, Spain
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27
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Funck T, Nicoli F, Kuzyk A, Liedl T. Sensing Picomolar Concentrations of RNA Using Switchable Plasmonic Chirality. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201807029] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Timon Funck
- Department für Physik; Ludwig-Maximilians-Universität; Geschwister-Scholl-Platz 1 80539 München Germany
| | - Francesca Nicoli
- Department für Physik; Ludwig-Maximilians-Universität; Geschwister-Scholl-Platz 1 80539 München Germany
| | - Anton Kuzyk
- Department of Neuroscience and Biomedical Engineering; Aalto University School of Science; P.O. Box 12200 00076 Aalto Finland
| | - Tim Liedl
- Department für Physik; Ludwig-Maximilians-Universität; Geschwister-Scholl-Platz 1 80539 München Germany
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28
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Funck T, Nicoli F, Kuzyk A, Liedl T. Sensing Picomolar Concentrations of RNA Using Switchable Plasmonic Chirality. Angew Chem Int Ed Engl 2018; 57:13495-13498. [DOI: 10.1002/anie.201807029] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Indexed: 01/02/2023]
Affiliation(s)
- Timon Funck
- Department für Physik; Ludwig-Maximilians-Universität; Geschwister-Scholl-Platz 1 80539 München Germany
| | - Francesca Nicoli
- Department für Physik; Ludwig-Maximilians-Universität; Geschwister-Scholl-Platz 1 80539 München Germany
| | - Anton Kuzyk
- Department of Neuroscience and Biomedical Engineering; Aalto University School of Science; P.O. Box 12200 00076 Aalto Finland
| | - Tim Liedl
- Department für Physik; Ludwig-Maximilians-Universität; Geschwister-Scholl-Platz 1 80539 München Germany
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29
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A Massively Parallel Selection of Small Molecule-RNA Motif Binding Partners Informs Design of an Antiviral from Sequence. Chem 2018; 4:2384-2404. [PMID: 30719503 DOI: 10.1016/j.chempr.2018.08.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Many RNAs cause disease; however, RNA is rarely exploited as a small-molecule drug target. Our programmatic focus is to define privileged RNA motif small-molecule interactions to enable the rational design of compounds that modulate RNA biology starting from only sequence. We completed a massive, library-versus-library screen that probed over 50 million binding events between RNA motifs and small molecules. The resulting data provide a rich encyclopedia of small-molecule RNA recognition patterns, defining chemotypes and RNA motifs that confer selective, avid binding. The resulting interaction maps were mined against the entire viral genome of hepatitis C virus (HCV). A small molecule was identified that avidly bound RNA motifs present in the HCV 30 UTR and inhibited viral replication while having no effect on host cells. Collectively, this study represents the first whole-genome pattern recognition between small molecules and RNA folds.
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30
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Bernier A, Sagan SM. The Diverse Roles of microRNAs at the Host⁻Virus Interface. Viruses 2018; 10:v10080440. [PMID: 30126238 PMCID: PMC6116274 DOI: 10.3390/v10080440] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 08/16/2018] [Accepted: 08/17/2018] [Indexed: 12/12/2022] Open
Abstract
MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression at the post-transcriptional level. Through this activity, they are implicated in almost every cellular process investigated to date. Hence, it is not surprising that miRNAs play diverse roles in regulation of viral infections and antiviral responses. Diverse families of DNA and RNA viruses have been shown to take advantage of cellular miRNAs or produce virally encoded miRNAs that alter host or viral gene expression. MiRNA-mediated changes in gene expression have been demonstrated to modulate viral replication, antiviral immune responses, viral latency, and pathogenesis. Interestingly, viruses mediate both canonical and non-canonical interactions with miRNAs to downregulate specific targets or to promote viral genome stability, translation, and/or RNA accumulation. In this review, we focus on recent findings elucidating several key mechanisms employed by diverse virus families, with a focus on miRNAs at the host–virus interface during herpesvirus, polyomavirus, retroviruses, pestivirus, and hepacivirus infections.
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Affiliation(s)
- Annie Bernier
- Department of Microbiology & Immunology, McGill University, Montréal, QC H3G 1Y6, Canada.
| | - Selena M Sagan
- Department of Microbiology & Immunology, McGill University, Montréal, QC H3G 1Y6, Canada.
- Department of Biochemistry, McGill University, Montréal, QC H3G 1Y6, Canada.
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31
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Schult P, Roth H, Adams RL, Mas C, Imbert L, Orlik C, Ruggieri A, Pyle AM, Lohmann V. microRNA-122 amplifies hepatitis C virus translation by shaping the structure of the internal ribosomal entry site. Nat Commun 2018; 9:2613. [PMID: 29973597 PMCID: PMC6031695 DOI: 10.1038/s41467-018-05053-3] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 06/11/2018] [Indexed: 12/24/2022] Open
Abstract
The liver-specific microRNA-122 (miR-122) recognizes two conserved sites at the 5′ end of the hepatitis C virus (HCV) genome and contributes to stability, translation, and replication of the viral RNA. We show that stimulation of the HCV internal ribosome entry site (IRES) by miR-122 is essential for efficient viral replication. The mechanism relies on a dual function of the 5′ terminal sequence in the complementary positive (translation) and negative strand (replication), requiring different secondary structures. Predictions and experimental evidence argue for several alternative folds involving the miR-binding region (MBR) adjacent to the IRES and interfering with its function. Mutations in the MBR, designed to suppress these dysfunctional structures indeed stimulate translation independently of miR-122. Conversely, MBR mutants favoring alternative folds show impaired IRES activity. Our results therefore suggest that miR-122 binding assists the folding of a functional IRES in an RNA chaperone-like manner by suppressing energetically favorable alternative secondary structures. The liver-specific microRNA-122 is an essential proviral host factor of Hepatitis C virus replication. Here the authors show that microRNA-122 functions as an RNA chaperone that guides the formation of a functional internal ribosome entry site by preventing energetically more favorable secondary structures within the HCV RNA genome.
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Affiliation(s)
- Philipp Schult
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Im Neuenheimer Feld 344, 69120, Heidelberg, Germany
| | - Hanna Roth
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Im Neuenheimer Feld 344, 69120, Heidelberg, Germany
| | - Rebecca L Adams
- Department of Molecular, Cellular and Developmental Biology, Yale University, 219 Prospect St, New Haven, CT, 06511, USA
| | - Caroline Mas
- University Grenoble Alpes, CNRS, CEA, IBS, 71 Avenue des Martyrs, CS 10090, 38044, Grenoble CEDEX 9, France
| | - Lionel Imbert
- University Grenoble Alpes, CNRS, CEA, IBS, 71 Avenue des Martyrs, CS 10090, 38044, Grenoble CEDEX 9, France
| | - Christian Orlik
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Im Neuenheimer Feld 344, 69120, Heidelberg, Germany.,Department of Immunology, Molecular Immunology, University of Heidelberg, 69120, Heidelberg, Germany
| | - Alessia Ruggieri
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Im Neuenheimer Feld 344, 69120, Heidelberg, Germany
| | - Anna M Pyle
- Department of Molecular, Cellular and Developmental Biology, Yale University, 219 Prospect St, New Haven, CT, 06511, USA.,Howard Hughes Medical Institute, 219 Prospect St, New Haven, CT, 06511, USA
| | - Volker Lohmann
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Im Neuenheimer Feld 344, 69120, Heidelberg, Germany.
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32
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Niepmann M, Shalamova LA, Gerresheim GK, Rossbach O. Signals Involved in Regulation of Hepatitis C Virus RNA Genome Translation and Replication. Front Microbiol 2018; 9:395. [PMID: 29593672 PMCID: PMC5857606 DOI: 10.3389/fmicb.2018.00395] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 02/21/2018] [Indexed: 12/15/2022] Open
Abstract
Hepatitis C virus (HCV) preferentially replicates in the human liver and frequently causes chronic infection, often leading to cirrhosis and liver cancer. HCV is an enveloped virus classified in the genus Hepacivirus in the family Flaviviridae and has a single-stranded RNA genome of positive orientation. The HCV RNA genome is translated and replicated in the cytoplasm. Translation is controlled by the Internal Ribosome Entry Site (IRES) in the 5' untranslated region (5' UTR), while also downstream elements like the cis-replication element (CRE) in the coding region and the 3' UTR are involved in translation regulation. The cis-elements controlling replication of the viral RNA genome are located mainly in the 5'- and 3'-UTRs at the genome ends but also in the protein coding region, and in part these signals overlap with the signals controlling RNA translation. Many long-range RNA-RNA interactions (LRIs) are predicted between different regions of the HCV RNA genome, and several such LRIs are actually involved in HCV translation and replication regulation. A number of RNA cis-elements recruit cellular RNA-binding proteins that are involved in the regulation of HCV translation and replication. In addition, the liver-specific microRNA-122 (miR-122) binds to two target sites at the 5' end of the viral RNA genome as well as to at least three additional target sites in the coding region and the 3' UTR. It is involved in the regulation of HCV RNA stability, translation and replication, thereby largely contributing to the hepatotropism of HCV. However, we are still far from completely understanding all interactions that regulate HCV RNA genome translation, stability, replication and encapsidation. In particular, many conclusions on the function of cis-elements in HCV replication have been obtained using full-length HCV genomes or near-full-length replicon systems. These include both genome ends, making it difficult to decide if a cis-element in question acts on HCV replication when physically present in the plus strand genome or in the minus strand antigenome. Therefore, it may be required to use reduced systems that selectively focus on the analysis of HCV minus strand initiation and/or plus strand initiation.
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Affiliation(s)
- Michael Niepmann
- Medical Faculty, Institute of Biochemistry, Justus Liebig University Giessen, Giessen, Germany
| | - Lyudmila A Shalamova
- Medical Faculty, Institute of Biochemistry, Justus Liebig University Giessen, Giessen, Germany.,Faculty of Biology and Chemistry, Institute of Biochemistry, Justus Liebig University Giessen, Giessen, Germany
| | - Gesche K Gerresheim
- Medical Faculty, Institute of Biochemistry, Justus Liebig University Giessen, Giessen, Germany.,Faculty of Biology and Chemistry, Institute of Biochemistry, Justus Liebig University Giessen, Giessen, Germany
| | - Oliver Rossbach
- Faculty of Biology and Chemistry, Institute of Biochemistry, Justus Liebig University Giessen, Giessen, Germany
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33
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Shi G, Suzuki T. Molecular Basis of Encapsidation of Hepatitis C Virus Genome. Front Microbiol 2018; 9:396. [PMID: 29563905 PMCID: PMC5845887 DOI: 10.3389/fmicb.2018.00396] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 02/21/2018] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV), a major etiologic agent of human liver diseases, is a positive-sense single-stranded RNA virus and is classified in the Flaviviridae family. Although research findings for the assembly of HCV particles are accumulating due to development of HCV cell culture system, the mechanism(s) by which the HCV genome becomes encapsidated remains largely unclear. In general, viral RNA represents only a small fraction of the RNA molecules in the cells infected with RNA viruses, but the viral genomic RNA is considered to selectively packaged into virions. It was recently demonstrated that HCV RNAs containing 3' end of the genome are selectively incorporated into virus particles during the assembly process and the 3' untranslated region functions as a cis-acting element for RNA packaging. Here, we discuss the molecular basis of RNA encapsidation of HCV and classical flaviviruses, contrast with the packaging mechanism of HIV-1.
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Affiliation(s)
- Guoli Shi
- Antiviral Immunity and Resistance Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, United States
| | - Tetsuro Suzuki
- Department of Virology and Parasitology, Hamamatsu University School of Medicine, Hamamatsu, Japan
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34
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Miyamura T, Lemon SM, Walker CM, Wakita T. The HCV Replicase Complex and Viral RNA Synthesis. HEPATITIS C VIRUS I 2016. [PMCID: PMC7122888 DOI: 10.1007/978-4-431-56098-2_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Replication of hepatitis C virus (HCV) is tightly linked to membrane alterations designated the membranous web, harboring the viral replicase complex. In this chapter we describe the morphology and 3D architecture of the HCV-induced replication organelles, mainly consisting of double membrane vesicles, which are generated by a concerted action of the nonstructural proteins NS3 to NS5B. Recent studies have furthermore identified a number of host cell proteins and lipids contributing to the biogenesis of the membranous web, which are discussed in this chapter. Viral RNA synthesis is tightly associated with these membrane alterations and mainly driven by the viral RNA dependent RNA polymerase NS5B. We summarize our current knowledge of the structure and function of NS5B, the role of cis-acting replication elements at the termini of the genome in regulating RNA synthesis and the contribution of additional viral and host factors to viral RNA synthesis, which is still ill defined.
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Affiliation(s)
- Tatsuo Miyamura
- National Institute of Infectious Diseases, Tokyo, Tokyo Japan
| | - Stanley M. Lemon
- Departments of Medicine and Microbiology & Immunology , The University of North Carolina, Chapel Hill, North Carolina USA
| | - Christopher M. Walker
- Center for Vaccines and Immunity, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio USA
| | - Takaji Wakita
- National Institute of Infectious Diseases, Tokyo, Tokyo Japan
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35
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Stewart H, Bingham R, White SJ, Dykeman EC, Zothner C, Tuplin AK, Stockley PG, Twarock R, Harris M. Identification of novel RNA secondary structures within the hepatitis C virus genome reveals a cooperative involvement in genome packaging. Sci Rep 2016; 6:22952. [PMID: 26972799 PMCID: PMC4789732 DOI: 10.1038/srep22952] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 02/19/2016] [Indexed: 12/11/2022] Open
Abstract
The specific packaging of the hepatitis C virus (HCV) genome is hypothesised to be driven by Core-RNA interactions. To identify the regions of the viral genome involved in this process, we used SELEX (systematic evolution of ligands by exponential enrichment) to identify RNA aptamers which bind specifically to Core in vitro. Comparison of these aptamers to multiple HCV genomes revealed the presence of a conserved terminal loop motif within short RNA stem-loop structures. We postulated that interactions of these motifs, as well as sub-motifs which were present in HCV genomes at statistically significant levels, with the Core protein may drive virion assembly. We mutated 8 of these predicted motifs within the HCV infectious molecular clone JFH-1, thereby producing a range of mutant viruses predicted to possess altered RNA secondary structures. RNA replication and viral titre were unaltered in viruses possessing only one mutated structure. However, infectivity titres were decreased in viruses possessing a higher number of mutated regions. This work thus identified multiple novel RNA motifs which appear to contribute to genome packaging. We suggest that these structures act as cooperative packaging signals to drive specific RNA encapsidation during HCV assembly.
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MESH Headings
- Aptamers, Nucleotide/chemistry
- Aptamers, Nucleotide/genetics
- Aptamers, Nucleotide/metabolism
- Base Sequence
- Blotting, Western
- Cell Line, Tumor
- Gene Expression Regulation, Viral
- Genome, Viral/genetics
- Hepacivirus/genetics
- Hepacivirus/metabolism
- Humans
- Mutation
- Nucleic Acid Conformation
- Nucleotide Motifs/genetics
- Protein Binding
- RNA, Viral/chemistry
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- SELEX Aptamer Technique
- Viral Core Proteins/genetics
- Viral Core Proteins/metabolism
- Viral Proteins/genetics
- Viral Proteins/metabolism
- Virus Assembly/genetics
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Affiliation(s)
- H. Stewart
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - R.J. Bingham
- York Centre for Complex Systems Analysis, Departments of Mathematics and Biology, University of York, York, YO10 5DD, United Kingdom
| | - S. J. White
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - E. C. Dykeman
- York Centre for Complex Systems Analysis, Departments of Mathematics and Biology, University of York, York, YO10 5DD, United Kingdom
| | - C. Zothner
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - A. K. Tuplin
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - P. G. Stockley
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - R. Twarock
- York Centre for Complex Systems Analysis, Departments of Mathematics and Biology, University of York, York, YO10 5DD, United Kingdom
| | - M. Harris
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
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36
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Shi G, Ando T, Suzuki R, Matsuda M, Nakashima K, Ito M, Omatsu T, Oba M, Ochiai H, Kato T, Mizutani T, Sawasaki T, Wakita T, Suzuki T. Involvement of the 3' Untranslated Region in Encapsidation of the Hepatitis C Virus. PLoS Pathog 2016; 12:e1005441. [PMID: 26867128 PMCID: PMC4750987 DOI: 10.1371/journal.ppat.1005441] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 01/15/2016] [Indexed: 02/06/2023] Open
Abstract
Although information regarding morphogenesis of the hepatitis C virus (HCV) is accumulating, the mechanism(s) by which the HCV genome encapsidated remains unknown. In the present study, in cell cultures producing HCV, the molecular ratios of 3’ end- to 5’ end-regions of the viral RNA population in the culture medium were markedly higher than those in the cells, and the ratio was highest in the virion-rich fraction. The interaction of the 3’ untranslated region (UTR) with Core in vitro was stronger than that of the interaction of other stable RNA structure elements across the HCV genome. A foreign gene flanked by the 3’ UTR was encapsidated by supplying both viral NS3-NS5B proteins and Core-NS2 in trans. Mutations within the conserved stem-loops of the 3’ UTR were observed to dramatically diminish packaging efficiency, suggesting that the conserved apical motifs of the 3´ X region are important for HCV genome packaging. This study provides evidence of selective packaging of the HCV genome into viral particles and identified that the 3’ UTR acts as a cis-acting element for encapsidation. Although cell culture systems provide a powerful tool for deciphering the life cycle of the hepatitis C virus (HCV), the mechanisms of encapsidation of the viral genome into infectious particles remain to be uncovered. The HCV genome is a positive RNA with one single reading frame flanked by 5’- and 3’ untranslated regions (UTRs). Thus far, there is no direct evidence that HCV employs a packaging-signal dependent- or replication-coupled mechanism of encapsidation of its genome. The possible overlap of RNA sequences that function in RNA replication with those that function in encapsidation may present an obstacle to investigation of the cis-elements for RNA packaging. In this study, we characterized the properties of HCV RNAs in a cell culture system by determining their integrity in virus-replicating cells and in culture supernatants, and we found that over-distributed 5’-subgenomes were negatively selected during virus assembly in the cells. Using trans-packaging systems with replication defective subgenomes, we identified the 3’UTR as a cis-acting element that was sufficient for packaging of not only a HCV subgenome but also a foreign gene into infectious particles. Mutagenesis analyses, together with an in vitro binding assay with Core demonstrated that, whereas the best encapsidation occurs with the entire 3’ UTR, the loop sequences of the 3’ X region appear to be essential for encapsidation. Our work opens new perspectives for understanding the molecular mechanisms that regulate the HCV life cycle and potentially paves a way to a new anti-viral therapy.
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Affiliation(s)
- Guoli Shi
- Department of Infectious Diseases, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Tomomi Ando
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan.,Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Ryosuke Suzuki
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Mami Matsuda
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kenji Nakashima
- Department of Infectious Diseases, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Masahiko Ito
- Department of Infectious Diseases, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Tsutomu Omatsu
- Research and Education center for Prevention of Global Infectious Diseases of Animals, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Mami Oba
- Research and Education center for Prevention of Global Infectious Diseases of Animals, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Hideharu Ochiai
- Research Institute of Biosciences, Azabu University, Kanagawa, Japan
| | - Takanobu Kato
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Tetsuya Mizutani
- Research and Education center for Prevention of Global Infectious Diseases of Animals, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | | | - Takaji Wakita
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Tetsuro Suzuki
- Department of Infectious Diseases, Hamamatsu University School of Medicine, Shizuoka, Japan
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37
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The yin and yang of hepatitis C: synthesis and decay of hepatitis C virus RNA. Nat Rev Microbiol 2015; 13:544-58. [PMID: 26256788 DOI: 10.1038/nrmicro3506] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hepatitis C virus (HCV) is an unusual RNA virus that has a striking capacity to persist for the remaining life of the host in the majority of infected individuals. In order to persist, HCV must balance viral RNA synthesis and decay in infected cells. In this Review, we focus on interactions between the positive-sense RNA genome of HCV and the host RNA-binding proteins and microRNAs, and describe how these interactions influence the competing processes of viral RNA synthesis and decay to achieve stable, long-term persistence of the viral genome. Furthermore, we discuss how these processes affect hepatitis C pathogenesis and therapeutic strategies against HCV.
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Fricke M, Dünnes N, Zayas M, Bartenschlager R, Niepmann M, Marz M. Conserved RNA secondary structures and long-range interactions in hepatitis C viruses. RNA (NEW YORK, N.Y.) 2015; 21:1219-32. [PMID: 25964384 PMCID: PMC4478341 DOI: 10.1261/rna.049338.114] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/07/2015] [Indexed: 05/02/2023]
Abstract
Hepatitis C virus (HCV) is a hepatotropic virus with a plus-strand RNA genome of ∼9.600 nt. Due to error-prone replication by its RNA-dependent RNA polymerase (RdRp) residing in nonstructural protein 5B (NS5B), HCV isolates are grouped into seven genotypes with several subtypes. By using whole-genome sequences of 106 HCV isolates and secondary structure alignments of the plus-strand genome and its minus-strand replication intermediate, we established refined secondary structures of the 5' untranslated region (UTR), the cis-acting replication element (CRE) in NS5B, and the 3' UTR. We propose an alternative structure in the 5' UTR, conserved secondary structures of 5B stem-loop (SL)1 and 5BSL2, and four possible structures of the X-tail at the very 3' end of the HCV genome. We predict several previously unknown long-range interactions, most importantly a possible circularization interaction between distinct elements in the 5' and 3' UTR, reminiscent of the cyclization elements of the related flaviviruses. Based on analogy to these viruses, we propose that the 5'-3' UTR base-pairing in the HCV genome might play an important role in viral RNA replication. These results may have important implications for our understanding of the nature of the cis-acting RNA elements in the HCV genome and their possible role in regulating the mutually exclusive processes of viral RNA translation and replication.
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Affiliation(s)
- Markus Fricke
- Faculty of Mathematics and Computer Science, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Nadia Dünnes
- Institute of Biochemistry, Medical Faculty, Justus-Liebig-University, 35392 Giessen, Germany
| | - Margarita Zayas
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Michael Niepmann
- Institute of Biochemistry, Medical Faculty, Justus-Liebig-University, 35392 Giessen, Germany
| | - Manja Marz
- Faculty of Mathematics and Computer Science, Friedrich Schiller University Jena, 07743 Jena, Germany FLI Leibniz Institute for Age Research, 07745 Jena, Germany
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Abstract
Hepatitis C virus (HCV) infects over 170 million people worldwide and is a leading cause of liver disease and cancer. The virus has a 9,650-nt, single-stranded, messenger-sense RNA genome that is infectious as an independent entity. The RNA genome has evolved in response to complex selection pressures, including the need to maintain structures that facilitate replication and to avoid clearance by cell-intrinsic immune processes. Here we used high-throughput, single-nucleotide resolution information to generate and functionally test data-driven structural models for three diverse HCV RNA genomes. We identified, de novo, multiple regions of conserved RNA structure, including all previously characterized cis-acting regulatory elements and also multiple novel structures required for optimal viral fitness. Well-defined RNA structures in the central regions of HCV genomes appear to facilitate persistent infection by masking the genome from RNase L and double-stranded RNA-induced innate immune sensors. This work shows how structure-first comparative analysis of entire genomes of a pathogenic RNA virus enables comprehensive and concise identification of regulatory elements and emphasizes the extensive interrelationships among RNA genome structure, viral biology, and innate immune responses.
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40
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Sagan SM, Chahal J, Sarnow P. cis-Acting RNA elements in the hepatitis C virus RNA genome. Virus Res 2015; 206:90-8. [PMID: 25576644 DOI: 10.1016/j.virusres.2014.12.029] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 12/12/2014] [Accepted: 12/24/2014] [Indexed: 12/22/2022]
Abstract
Hepatitis C virus (HCV) infection is a rapidly increasing global health problem with an estimated 170 million people infected worldwide. HCV is a hepatotropic, positive-sense RNA virus of the family Flaviviridae. As a positive-sense RNA virus, the HCV genome itself must serve as a template for translation, replication and packaging. The viral RNA must therefore be a dynamic structure that is able to readily accommodate structural changes to expose different regions of the genome to viral and cellular proteins to carry out the HCV life cycle. The ∼ 9600 nucleotide viral genome contains a single long open reading frame flanked by 5' and 3' non-coding regions that contain cis-acting RNA elements important for viral translation, replication and stability. Additional cis-acting RNA elements have also been identified in the coding sequences as well as in the 3' end of the negative-strand replicative intermediate. Herein, we provide an overview of the importance of these cis-acting RNA elements in the HCV life cycle.
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Affiliation(s)
- Selena M Sagan
- Department of Microbiology & Immunology, McGill University, Montreal, QC, Canada
| | - Jasmin Chahal
- Department of Microbiology & Immunology, McGill University, Montreal, QC, Canada
| | - Peter Sarnow
- Department of Microbiology and Immunology, Stanford University, Stanford, CA, United States.
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Hepatitis C virus and human miR-122: insights from the bench to the clinic. Curr Opin Virol 2014; 7:11-8. [PMID: 24721497 DOI: 10.1016/j.coviro.2014.03.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 03/07/2014] [Accepted: 03/10/2014] [Indexed: 12/19/2022]
Abstract
MicroRNAs (miRNAs) are small non-coding RNAs that function as part of RNA-induced silencing complexes that repress the expression of target genes. Over the past few years, miRNAs have been found to mediate complex regulation of a wide variety of mammalian viral infections, including Hepatitis C virus (HCV) infection. Here, we focus on a highly abundant, liver-specific miRNA, miR-122. In a unique and unusual interaction, miR-122 binds to two sites in the 5' untranslated region (UTR) of the HCV genome and promotes viral RNA accumulation. We will discuss what has been learned about this important interaction to date, provide insights into how miR-122 is able to modulate HCV RNA accumulation, and how miR-122 might be exploited for antiviral intervention.
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Abstract
Genome replication is a crucial step in the life cycle of any virus. HCV is a positive strand RNA virus and requires a set of nonstructural proteins (NS3, 4A, 4B, 5A, and 5B) as well as cis-acting replication elements at the genome termini for amplification of the viral RNA. All nonstructural proteins are tightly associated with membranes derived from the endoplasmic reticulum and induce vesicular membrane alterations designated the membranous web, harboring the viral replication sites. The viral RNA-dependent RNA polymerase NS5B is the key enzyme of RNA synthesis. Structural, biochemical, and reverse genetic studies have revealed important insights into the mode of action of NS5B and the mechanism governing RNA replication. Although a comprehensive understanding of the regulation of RNA synthesis is still missing, a number of important viral and host determinants have been defined. This chapter summarizes our current knowledge on the role of viral and host cell proteins as well as cis-acting replication elements involved in the biogenesis of the membranous web and in viral RNA synthesis.
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Affiliation(s)
- Volker Lohmann
- Department of Infectious Diseases, University of Heidelberg, Heidelberg, Germany.
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43
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Modulation of GB virus B RNA abundance by microRNA-122: dependence on and escape from microRNA-122 restriction. J Virol 2013; 87:7338-47. [PMID: 23616647 DOI: 10.1128/jvi.00378-13] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Hepatitis C virus (HCV) RNA forms an unusual interaction with human microRNA-122 (miR-122) that promotes viral RNA accumulation in cultured human liver cells and in the livers of infected chimpanzees. GB virus B (GBV-B) is a hepatotropic virus and close relative of HCV. Thus, GBV-B has been used as a surrogate system to study HCV amplification in cultured cells and in infected tamarins. It was discovered that the 5'-terminal sequences of GBV-B RNA, like HCV RNA, forms an Argonaute 2-mediated complex with two miR-122 molecules that are essential for accumulation of GBV-B subgenomic replicon RNA. However, sequences in miR-122 that anneal to each viral RNA genome were different, suggesting distinct overall structural features in HCV:miR-122 and GBV-B:miR-122 complexes. Surprisingly, a deletion that removed both miR-122 binding sites from the subgenomic GBV-B RNAs rendered viral RNA amplification independent from miR-122 and Argonaute 2. This finding suggests that structural features at the end of the viral genome dictate whether miR-122 is required to aid in maintaining viral RNA abundance.
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Conrad KD, Giering F, Erfurth C, Neumann A, Fehr C, Meister G, Niepmann M. MicroRNA-122 dependent binding of Ago2 protein to hepatitis C virus RNA is associated with enhanced RNA stability and translation stimulation. PLoS One 2013; 8:e56272. [PMID: 23405269 PMCID: PMC3566042 DOI: 10.1371/journal.pone.0056272] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 01/08/2013] [Indexed: 01/16/2023] Open
Abstract
Translation of Hepatitis C Virus (HCV) RNA is directed by an internal ribosome entry site (IRES) in the 5′-untranslated region (5′-UTR). HCV translation is stimulated by the liver-specific microRNA-122 (miR-122) that binds to two binding sites between the stem-loops I and II near the 5′-end of the 5′-UTR. Here, we show that Argonaute (Ago) 2 protein binds to the HCV 5′-UTR in a miR-122-dependent manner, whereas the HCV 3′-UTR does not bind Ago2. miR-122 also recruits Ago1 to the HCV 5’-UTR. Only miRNA duplex precursors of the correct length stimulate HCV translation, indicating that the duplex miR-122 precursors are unwound by a complex that measures their length. Insertions in the 5′-UTR between the miR-122 binding sites and the IRES only slightly decrease translation stimulation by miR-122. In contrast, partially masking the miR-122 binding sites in a stem-loop structure impairs Ago2 binding and translation stimulation by miR-122. In an RNA decay assay, also miR-122-mediated RNA stability contributes to HCV translation stimulation. These results suggest that Ago2 protein is directly involved in loading miR-122 to the HCV RNA and mediating RNA stability and translation stimulation.
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Affiliation(s)
- K. Dominik Conrad
- Institute of Biochemistry, Faculty of Medicine, Justus-Liebig-University, Giessen, Germany
| | - Florian Giering
- Institute of Biochemistry, Faculty of Medicine, Justus-Liebig-University, Giessen, Germany
| | - Corinna Erfurth
- Institute of Biochemistry, Faculty of Medicine, Justus-Liebig-University, Giessen, Germany
| | - Angelina Neumann
- Institute of Biochemistry, Faculty of Medicine, Justus-Liebig-University, Giessen, Germany
| | - Carmen Fehr
- Institute of Biochemistry, Faculty of Medicine, Justus-Liebig-University, Giessen, Germany
| | - Gunter Meister
- Institute of Biochemistry, Faculty of Biology and Preclinical Medicine, University of Regensburg, Regensburg, Germany
| | - Michael Niepmann
- Institute of Biochemistry, Faculty of Medicine, Justus-Liebig-University, Giessen, Germany
- * E-mail:
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Samreen B, Khaliq S, Ashfaq UA, Khan M, Afzal N, Shahzad MA, Riaz S, Jahan S. Hepatitis C virus entry: role of host and viral factors. INFECTION GENETICS AND EVOLUTION 2012; 12:1699-709. [PMID: 22878095 DOI: 10.1016/j.meegid.2012.07.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 07/13/2012] [Accepted: 07/16/2012] [Indexed: 12/24/2022]
Abstract
Hepatitis C virus (HCV) has been considered to be a significant risk factor in developing liver associated diseases including hepatocellular carcinoma all over the world. HCV is an enveloped positive strand virus comprising a complex between genomic RNA and viral envelope glycoproteins (E1 and E2), which are anchored within host derived double-layered lipid membrane surrounding the nucleocapsid composed of several copies of core protein. HCV cell entry is the first step in infection and viral replication into host cells mainly hepatocytes. HCV cell entry is a complex process involving both the viral (envelope glycoproteins E1/E2) and host factors (cellular receptors and associated factors i.e. CD81, SR-BI, LDL-R, CLDN1, Occludin, DC-SIGN, L-SIGN and Glycosaminoglycans). Besides these the expression of certain other conditions such as polarization and EWI-2 expression inhibits the viral cell entry. Exploring the mechanism of HCV entry will help to better understand the viral life cycle and possible therapeutic targets against HCV infection including viral and host factors involved in this process. New strategies such as RNAi represents a new option for targeting the host or viral factors for prevention and therapeutic against HCV infection. In the current review we try to summarize the current knowledge about mechanism and interaction of cellular and viral factors involved in HCV cell entry and its implication as therapeutic target to inhibit HCV infection.
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Affiliation(s)
- Baila Samreen
- National Center of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
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Caval V, Piver E, Ivanyi-Nagy R, Darlix JL, Pagès JC. Packaging of HCV-RNA into lentiviral vector. Biochem Biophys Res Commun 2011; 414:808-13. [PMID: 22008549 DOI: 10.1016/j.bbrc.2011.10.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 10/04/2011] [Indexed: 12/16/2022]
Abstract
The advent of infectious molecular clones of Hepatitis C virus (HCV) has unlocked the understanding of HCV life cycle. However, packaging of the genomic RNA, which is crucial to generate infectious viral particles, remains poorly understood. Molecular interactions of the domain 1 (D1) of HCV Core protein and HCV RNA have been described in vitro. Since compaction of genetic information within HCV genome has hampered conventional mutational approach to study packaging in vivo, we developed a novel heterologous system to evaluate the interactions between HCV RNA and CoreD1. For this, we took advantage of the recruitment of Vpr fusion-proteins into HIV-1 particles. By fusing HCV Core D1 to Vpr we were able to package and transfer a HCV subgenomic replicon into a HIV-1 based lentiviral vector. We next examined how deletion mutants of basic sub-domains of Core D1 influenced HCV RNA recruitment. The results emphasized the crucial role of the first and third basic regions of D1 in packaging. Interestingly, the system described here allowed us to mobilise full-length JFH1 genome in CD81 defective cells, which are normally refractory to HCV infection. This finding paves the way to an evaluation of the replication capability of HCV in various cell types.
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Affiliation(s)
- Vincent Caval
- INSERM U966, Université François Rabelais de Tours, Faculté de Médecine, 10 Bd. Tonnellé, 37000 Tours, France
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47
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Konno K, Iizuka M, Fujita S, Nishikawa S, Hasegawa T, Fukuda K. An RNA aptamer containing two binding sites against the HCV minus-IRES domain I. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2011; 30:185-202. [PMID: 21491328 DOI: 10.1080/15257770.2011.562475] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The higher order structure of HCV (-)IRES containing five stem-loop structures (domain I) is essential for HCV replication because the viral RNA-dependent RNA polymerase, NS5B, recognizes it as the initiation site for plus-strand synthesis. To inhibit a de novo synthesis of plus-strand RNA molecules, in vitro selection against (-)IRES domain I was performed. One of the obtained aptamers, AP30, contained two consensus sequences within a random sequence region. Two consensus sequences form two apical loops and mutational analysis showed that both sequences were essential for binding to the target and for inhibiting NS5B-mediated RNA synthesis in vitro.
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Affiliation(s)
- Keisuke Konno
- Department of Material and Biological Chemistry, Faculty of Science, Yamagata University, Yamagata, Japan
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48
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Prabdial-Sing N, Giangaspero M, Puren AJ, Mahlangu J, Barrow P, Bowyer SM. Palindromic-nucleotide substitutions (PNS) of hepatitis C virus genotypes 1 and 5a from South Africa. J Virol Methods 2011; 175:272-7. [PMID: 21600241 DOI: 10.1016/j.jviromet.2011.05.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 04/20/2011] [Accepted: 05/03/2011] [Indexed: 02/05/2023]
Abstract
The HCV stem-loop subdomains III-a, -b and -c have been shown to reflect the characteristics of the virus and identify isolates by genus, genotype and subtype. The aim of this study was to investigate the genotype-specific PNS within the 5'UTR of prevalent HCV genotypes (1 and 5a) found in South Africa. The genotype 5a (N = 35) and genotype 1 sequences (N=20) were from patients presenting with liver disease or haemophilia, respectively. PNS HCV typing characteristics, defined previously, were observed. The PNS method differentiated subtypes 1a and 1c from subtype 1b by the base change at nucleotide position 243. A lack of structural data from the variable loci V1 of the 5'UTR did not allow us to further differentiate the subtypes of 1. A nucleotide change from a thymine (T) to a cytosine (C) at position 183 was found among genotype 5a sequences. This mutation changed the stable U-AA bond to a Y AA bulge at base-pair position 32. There was an insertion of a single adenine (A) at position 207. At present PNS analysis is labour intensive but, with development of further software to aid the computer analysis, it has the potential to provide a rapid, reliable alternative to phylogenetic analysis.
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Affiliation(s)
- N Prabdial-Sing
- Specialized Molecular Diagnostics, Hepatitis Unit, National Institute for Communicable Diseases (NICD), of the National Health Laboratory Services (NHLS), Private bag 4, Sandringham 2131, South Africa..
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49
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Xiao M, Wang Y, Zhu Z, Ding C, Yu J, Wan L, Chen J. Influence of the 5'-proximal elements of the 5'-untranslated region of classical swine fever virus on translation and replication. J Gen Virol 2011; 92:1087-1096. [PMID: 21307229 DOI: 10.1099/vir.0.027870-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The 5'-terminal sequence spanning nt 1-29 of the 5'-untranslated region of classical swine fever virus (CSFV) forms a 5'-proximal stem-loop structure known as domain Ia. Deletions and replacement mutations were performed to examine the role of this domain. Deletion of the 5'-proximal nucleotides and disruption of the stem-loop structure greatly increased internal ribosome entry site-mediated translation but abolished the replication of the replicons. Internal deletions resulting in a change in the size of the loop of domain Ia, and even removal of the entire domain, did not substantially change the translation activity, but reduced the replication of CSFV replicons provided the replicons contained the extreme 5'-GUAU terminal sequence. Internal replacements leading to a change in the nucleotide sequence of the loop did not alter the translation and replication activities of the CSFV RNA replicon, and did not influence the rescue of viruses and growth characteristics of new viruses. These results may be important for our understanding of the regulation of translation, replication and encapsidation in CSFV and other positive-sense RNA viruses.
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Affiliation(s)
- Ming Xiao
- College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, PR China
| | - Yujing Wang
- College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, PR China
| | - Zailing Zhu
- College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, PR China
| | - Chengli Ding
- College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, PR China
| | - Jialin Yu
- College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, PR China
| | - Lingzhu Wan
- College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, PR China
| | - Jun Chen
- College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, PR China
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50
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Jangra RK, Yi M, Lemon SM. Regulation of hepatitis C virus translation and infectious virus production by the microRNA miR-122. J Virol 2010; 84:6615-25. [PMID: 20427538 PMCID: PMC2903297 DOI: 10.1128/jvi.00417-10] [Citation(s) in RCA: 254] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Accepted: 04/16/2010] [Indexed: 12/14/2022] Open
Abstract
miR-122 is a liver-specific microRNA that positively regulates hepatitis C virus (HCV) RNA abundance and is essential for production of infectious HCV. Using a genetic approach, we show that its ability to enhance yields of infectious virus is dependent upon two miR-122-binding sites near the 5' end of the HCV genome, S1 and S2. Viral RNA with base substitutions in both S1 and S2 failed to produce infectious virus in transfected cells, while virus production was rescued to near-wild-type levels in cells supplemented with a complementary miR-122 mutant. A comparison of mutants with substitutions in only one site revealed S1 to be dominant, as an S2 but not S1 mutant produced high virus yields in cells supplemented with wild-type miR-122. Translation of HCV RNA was reduced over 50% by mutations in either S1 or S2 and was partially rescued by transfection of the complementary miR-122 mutant. Unlike the case for virus replication, however, both sites function equally in regulating translation. We conclude that miR-122 promotes replication by binding directly to both sites in the genomic RNA and, at least in part, by stimulating internal ribosome entry site (IRES)-mediated translation. However, a comparison of the replication capacities of the double-binding-site mutant and an IRES mutant with a quantitatively equivalent defect in translation suggests that the decrement in translation associated with loss of miR-122 binding is insufficient to explain the profound defect in virus production by the double mutant. miR-122 is thus likely to act at an additional step in the virus life cycle.
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Affiliation(s)
- Rohit K. Jangra
- Center for Hepatitis Research, Institute for Human Infections and Immunity, and Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas 77555-0610
| | - MinKyung Yi
- Center for Hepatitis Research, Institute for Human Infections and Immunity, and Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas 77555-0610
| | - Stanley M. Lemon
- Center for Hepatitis Research, Institute for Human Infections and Immunity, and Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas 77555-0610
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