1
|
Triebel S, Lamkiewicz K, Ontiveros N, Sweeney B, Stadler PF, Petrov AI, Niepmann M, Marz M. Comprehensive survey of conserved RNA secondary structures in full-genome alignment of Hepatitis C virus. Sci Rep 2024; 14:15145. [PMID: 38956134 PMCID: PMC11219754 DOI: 10.1038/s41598-024-62897-0] [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: 12/19/2023] [Accepted: 05/22/2024] [Indexed: 07/04/2024] Open
Abstract
Hepatitis C virus (HCV) is a plus-stranded RNA virus that often chronically infects liver hepatocytes and causes liver cirrhosis and cancer. These viruses replicate their genomes employing error-prone replicases. Thereby, they routinely generate a large 'cloud' of RNA genomes (quasispecies) which-by trial and error-comprehensively explore the sequence space available for functional RNA genomes that maintain the ability for efficient replication and immune escape. In this context, it is important to identify which RNA secondary structures in the sequence space of the HCV genome are conserved, likely due to functional requirements. Here, we provide the first genome-wide multiple sequence alignment (MSA) with the prediction of RNA secondary structures throughout all representative full-length HCV genomes. We selected 57 representative genomes by clustering all complete HCV genomes from the BV-BRC database based on k-mer distributions and dimension reduction and adding RefSeq sequences. We include annotations of previously recognized features for easy comparison to other studies. Our results indicate that mainly the core coding region, the C-terminal NS5A region, and the NS5B region contain secondary structure elements that are conserved beyond coding sequence requirements, indicating functionality on the RNA level. In contrast, the genome regions in between contain less highly conserved structures. The results provide a complete description of all conserved RNA secondary structures and make clear that functionally important RNA secondary structures are present in certain HCV genome regions but are largely absent from other regions. Full-genome alignments of all branches of Hepacivirus C are provided in the supplement.
Collapse
Affiliation(s)
- Sandra Triebel
- RNA Bioinformatics and High-Throughput Analysis, Friedrich Schiller University Jena, 07743, Jena, Germany
- European Virus Bioinformatics Center, Friedrich Schiller University Jena, 07743, Jena, Germany
| | - Kevin Lamkiewicz
- RNA Bioinformatics and High-Throughput Analysis, Friedrich Schiller University Jena, 07743, Jena, Germany
- European Virus Bioinformatics Center, Friedrich Schiller University Jena, 07743, Jena, Germany
| | - Nancy Ontiveros
- European Molecular Biology Laboratory, Wellcome Genome Campus, European Bioinformatics Institute, Hinxton, Cambridge, CB10 1SD, UK
| | - Blake Sweeney
- European Molecular Biology Laboratory, Wellcome Genome Campus, European Bioinformatics Institute, Hinxton, Cambridge, CB10 1SD, UK
| | - Peter F Stadler
- European Virus Bioinformatics Center, Friedrich Schiller University Jena, 07743, Jena, Germany
- Bioinformatics Group, Institute of Computer Science, and Interdisciplinary Center for Bioinformatics, University Leipzig, 04107, Leipzig, Germany
- German Center for Integrative Biodiversity Research (iDiv), 04103, Leipzig, Germany
| | | | - Michael Niepmann
- Institute for Biochemistry, Justus-Liebig-University Giessen, 35392, Giessen, Germany
| | - Manja Marz
- RNA Bioinformatics and High-Throughput Analysis, Friedrich Schiller University Jena, 07743, Jena, Germany.
- European Virus Bioinformatics Center, Friedrich Schiller University Jena, 07743, Jena, Germany.
- Leibniz Institute on Aging-Fritz Lipmann Institute, 07745, Jena, Germany.
- German Center for Integrative Biodiversity Research (iDiv), 04103, Leipzig, Germany.
- Michael Stifel Center Jena, Friedrich Schiller University Jena, 07743, Jena, Germany.
- Cluster of Excellence Balance of the Microverse, Friedrich Schiller University Jena, 07743, Jena, Germany.
| |
Collapse
|
2
|
van den Akker GGH, Zacchini F, Housmans BAC, van der Vloet L, Caron MMJ, Montanaro L, Welting TJM. Current Practice in Bicistronic IRES Reporter Use: A Systematic Review. Int J Mol Sci 2021; 22:5193. [PMID: 34068921 PMCID: PMC8156625 DOI: 10.3390/ijms22105193] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/05/2021] [Accepted: 05/12/2021] [Indexed: 12/26/2022] Open
Abstract
Bicistronic reporter assays have been instrumental for transgene expression, understanding of internal ribosomal entry site (IRES) translation, and identification of novel cap-independent translational elements (CITE). We observed a large methodological variability in the use of bicistronic reporter assays and data presentation or normalization procedures. Therefore, we systematically searched the literature for bicistronic IRES reporter studies and analyzed methodological details, data visualization, and normalization procedures. Two hundred fifty-seven publications were identified using our search strategy (published 1994-2020). Experimental studies on eukaryotic adherent cell systems and the cell-free translation assay were included for further analysis. We evaluated the following methodological details for 176 full text articles: the bicistronic reporter design, the cell line or type, transfection methods, and time point of analyses post-transfection. For the cell-free translation assay, we focused on methods of in vitro transcription, type of translation lysate, and incubation times and assay temperature. Data can be presented in multiple ways: raw data from individual cistrons, a ratio of the two, or fold changes thereof. In addition, many different control experiments have been suggested when studying IRES-mediated translation. In addition, many different normalization and control experiments have been suggested when studying IRES-mediated translation. Therefore, we also categorized and summarized their use. Our unbiased analyses provide a representative overview of bicistronic IRES reporter use. We identified parameters that were reported inconsistently or incompletely, which could hamper data reproduction and interpretation. On the basis of our analyses, we encourage adhering to a number of practices that should improve transparency of bicistronic reporter data presentation and improve methodological descriptions to facilitate data replication.
Collapse
Affiliation(s)
- Guus Gijsbertus Hubert van den Akker
- Department of Orthopedic Surgery, Maastricht University, Medical Center+, 6229 ER Maastricht, The Netherlands; (G.G.H.v.d.A.); (B.A.C.H.); (L.v.d.V.); (M.M.J.C.)
| | - Federico Zacchini
- Department of Experimental, Diagnostic and Specialty Medicine, Bologna University, I-40138 Bologna, Italy; (F.Z.); (L.M.)
- Centro di Ricerca Biomedica Applicata—CRBA, Bologna University, Policlinico di Sant’Orsola, I-40138 Bologna, Italy
| | - Bas Adrianus Catharina Housmans
- Department of Orthopedic Surgery, Maastricht University, Medical Center+, 6229 ER Maastricht, The Netherlands; (G.G.H.v.d.A.); (B.A.C.H.); (L.v.d.V.); (M.M.J.C.)
| | - Laura van der Vloet
- Department of Orthopedic Surgery, Maastricht University, Medical Center+, 6229 ER Maastricht, The Netherlands; (G.G.H.v.d.A.); (B.A.C.H.); (L.v.d.V.); (M.M.J.C.)
| | - Marjolein Maria Johanna Caron
- Department of Orthopedic Surgery, Maastricht University, Medical Center+, 6229 ER Maastricht, The Netherlands; (G.G.H.v.d.A.); (B.A.C.H.); (L.v.d.V.); (M.M.J.C.)
| | - Lorenzo Montanaro
- Department of Experimental, Diagnostic and Specialty Medicine, Bologna University, I-40138 Bologna, Italy; (F.Z.); (L.M.)
- Centro di Ricerca Biomedica Applicata—CRBA, Bologna University, Policlinico di Sant’Orsola, I-40138 Bologna, Italy
- Programma Dipartimentale in Medicina di Laboratorio, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Via Albertoni 15, I-40138 Bologna, Italy
| | - Tim Johannes Maria Welting
- Department of Orthopedic Surgery, Maastricht University, Medical Center+, 6229 ER Maastricht, The Netherlands; (G.G.H.v.d.A.); (B.A.C.H.); (L.v.d.V.); (M.M.J.C.)
| |
Collapse
|
3
|
Vassilaki N, Frakolaki E, Kalliampakou KI, Sakellariou P, Kotta-Loizou I, Bartenschlager R, Mavromara P. A Novel Cis-Acting RNA Structural Element Embedded in the Core Coding Region of the Hepatitis C Virus Genome Directs Internal Translation Initiation of the Overlapping Core+1 ORF. Int J Mol Sci 2020; 21:ijms21186974. [PMID: 32972019 PMCID: PMC7554737 DOI: 10.3390/ijms21186974] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/04/2020] [Accepted: 09/18/2020] [Indexed: 02/07/2023] Open
Abstract
Hepatitis C virus (HCV) genome translation is initiated via an internal ribosome entry site (IRES) embedded in the 5'-untranslated region (5'UTR). We have earlier shown that the conserved RNA stem-loops (SL) SL47 and SL87 of the HCV core-encoding region are important for viral genome translation in cell culture and in vivo. Moreover, we have reported that an open reading frame overlapping the core gene in the +1 frame (core+1 ORF) encodes alternative translation products, including a protein initiated at the internal AUG codons 85/87 of this frame (nt 597-599 and 603-605), downstream of SL87, which is designated core+1/Short (core+1/S). Here, we provide evidence for SL47 and SL87 possessing a novel cis-acting element that directs the internal translation initiation of core+1/S. Firstly, using a bicistronic dual luciferase reporter system and RNA-transfection experiments, we found that nucleotides 344-596 of the HCV genotype-1a and -2a genomes support translation initiation at the core+1 frame AUG codons 85/87, when present in the sense but not the opposite orientation. Secondly, site-directed mutagenesis combined with an analysis of ribosome-HCV RNA association elucidated that SL47 and SL87 are essential for this alternative translation mechanism. Finally, experiments using cells transfected with JFH1 replicons or infected with virus-like particles showed that core+1/S expression is independent from the 5'UTR IRES and does not utilize the polyprotein initiation codon, but it requires intact SL47 and SL87 structures. Thus, SL47 and SL87, apart from their role in viral polyprotein translation, are necessary elements for mediating the internal translation initiation of the alternative core+1/S ORF.
Collapse
Affiliation(s)
- Niki Vassilaki
- Molecular Virology Laboratory, Hellenic Pasteur Institute (HPI), 11521 Athens, Greece; (E.F.); (K.I.K.); (P.S.); (I.K.-L.)
- Correspondence: (N.V.); (P.M.)
| | - Efseveia Frakolaki
- Molecular Virology Laboratory, Hellenic Pasteur Institute (HPI), 11521 Athens, Greece; (E.F.); (K.I.K.); (P.S.); (I.K.-L.)
| | - Katerina I. Kalliampakou
- Molecular Virology Laboratory, Hellenic Pasteur Institute (HPI), 11521 Athens, Greece; (E.F.); (K.I.K.); (P.S.); (I.K.-L.)
| | - Panagiotis Sakellariou
- Molecular Virology Laboratory, Hellenic Pasteur Institute (HPI), 11521 Athens, Greece; (E.F.); (K.I.K.); (P.S.); (I.K.-L.)
| | - Ioly Kotta-Loizou
- Molecular Virology Laboratory, Hellenic Pasteur Institute (HPI), 11521 Athens, Greece; (E.F.); (K.I.K.); (P.S.); (I.K.-L.)
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, 69120 Heidelberg, Germany;
- German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Penelope Mavromara
- Molecular Virology Laboratory, Hellenic Pasteur Institute (HPI), 11521 Athens, Greece; (E.F.); (K.I.K.); (P.S.); (I.K.-L.)
- Laboratory of Biochemistry and Molecular Virology, Department of Molecular Biology and Genetics, Democritus University of Thrace, 68100 Thrace, Greece
- Correspondence: (N.V.); (P.M.)
| |
Collapse
|
4
|
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: 4.0] [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.
Collapse
|
5
|
Berzal-Herranz A, Romero-López C, Berzal-Herranz B, Ramos-Lorente S. Potential of the Other Genetic Information Coded by the Viral RNA Genomes as Antiviral Target. Pharmaceuticals (Basel) 2019; 12:38. [PMID: 30871174 PMCID: PMC6469156 DOI: 10.3390/ph12010038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 03/07/2019] [Accepted: 03/10/2019] [Indexed: 02/05/2023] Open
Abstract
In addition to the protein coding information, viral RNA genomes code functional information in structurally conserved units termed functional RNA domains. These RNA domains play essential roles in the viral cycle (e.g., replication and translation). Understanding the molecular mechanisms behind their function is essential to understanding the viral infective cycle. Further, interfering with the function of the genomic RNA domains offers a potential means of developing antiviral strategies. Aptamers are good candidates for targeting structural RNA domains. Besides its potential as therapeutics, aptamers also provide an excellent tool for investigating the functionality of RNA domains in viral genomes. This review briefly summarizes the work carried out in our laboratory aimed at the structural and functional characterization of the hepatitis C virus (HCV) genomic RNA domains. It also describes the efforts we carried out for the development of antiviral aptamers targeting specific genomic domains of the HCV and the human immunodeficiency virus type-1 (HIV-1).
Collapse
Affiliation(s)
- Alfredo Berzal-Herranz
- Instituto de Parasitología y Biomedicina López-Neyra, (IPBLN-CSIC); Av. del Conocimiento 17, PTS Granada, Armilla, 18016 Granada, Spain.
| | - Cristina Romero-López
- Instituto de Parasitología y Biomedicina López-Neyra, (IPBLN-CSIC); Av. del Conocimiento 17, PTS Granada, Armilla, 18016 Granada, Spain.
| | - Beatriz Berzal-Herranz
- Instituto de Parasitología y Biomedicina López-Neyra, (IPBLN-CSIC); Av. del Conocimiento 17, PTS Granada, Armilla, 18016 Granada, Spain.
| | - Sara Ramos-Lorente
- Instituto de Parasitología y Biomedicina López-Neyra, (IPBLN-CSIC); Av. del Conocimiento 17, PTS Granada, Armilla, 18016 Granada, Spain.
| |
Collapse
|
6
|
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: 0.5] [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.
Collapse
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.
| |
Collapse
|
7
|
Chen M, Zheng F, Yuan G, Duan X, Rong L, Liu J, Feng S, Wang Z, Wang M, Feng Y, Zhou Q, Li J, Deng K, Li C, Xia J, Rao G, Zhou Y, Fu Y, Li YP. Development of an Infectious Cell Culture System for Hepatitis C Virus Genotype 6a Clinical Isolate Using a Novel Strategy and Its Sensitivity to Direct-Acting Antivirals. Front Microbiol 2018; 9:2950. [PMID: 30564209 PMCID: PMC6288186 DOI: 10.3389/fmicb.2018.02950] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 11/16/2018] [Indexed: 12/16/2022] Open
Abstract
Hepatitis C virus (HCV) is classified into seven major genotypes, and genotype 6 is commonly prevalent in Asia, thus reverse genetic system representing genotype 6 isolates in prevalence is required. Here, we developed an infectious clone for a Chinese HCV 6a isolate (CH6a) using a novel strategy. We determined CH6a consensus sequence from patient serum and assembled a CH6a full-length (CH6aFL) cDNA using overlapped PCR product-derived clones that shared the highest homology with the consensus. CH6aFL was non-infectious in hepatoma Huh7.5 cells. Next, we constructed recombinants containing Core-NS5A or 5′UTR-NS5A from CH6a and the remaining sequences from JFH1 (genotype 2a), and both were engineered with 7 mutations identified previously. However, they replicated inefficiently without virus spread in Huh7.5 cells. Addition of adaptive mutations from CH6a Core-NS2 recombinant, with JFH1 5′UTR and NS3-3′UTR, enhanced the viability of Core-NS5A recombinant and acquired replication-enhancing mutations. Combination of 22 mutations in CH6a recombinant with JFH1 5′UTR and 3′UTR (CH6aORF) enabled virus replication and recovered additional four mutations. Adding these four mutations, we generated two efficient recombinants containing 26 mutations (26m), CH6aORF_26m and CH6aFL_26m (designated “CH6acc”), releasing HCV of 104.3–104.5 focus-forming units (FFU)/ml in Huh7.5.1-VISI-mCherry and Huh7.5 cells. Seven newly identified mutations were important for HCV replication, assembly, and release. The CH6aORF_26m virus was inhibited in a dose- and genotype-dependent manner by direct-acting-antivirals targeting NS3/4A, NS5A, and NS5B. The CH6acc enriches the toolbox of HCV culture systems, and the strategy and mutations applied here will facilitate the culture development of other HCV isolates and related viruses.
Collapse
Affiliation(s)
- Mingxiao Chen
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Fuxiang Zheng
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Guosheng Yuan
- Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Xiaobing Duan
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Liang Rong
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Junwei Liu
- Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Shengjun Feng
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Ziting Wang
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Min Wang
- Guangzhou Blood Center, Guangzhou, China
| | - Yetong Feng
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Qing Zhou
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Jinqian Li
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Kai Deng
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Chunna Li
- Program of Pathobiology, The Fifth Affiliated Hospital and Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China
| | - Jinyu Xia
- Program of Pathobiology, The Fifth Affiliated Hospital and Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China
| | - Guirong Rao
- Key Laboratory of Liver Disease, Center of Infectious Diseases, PLA 458 Hospital, Guangzhou, China
| | - Yuanping Zhou
- Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | | | - Yi-Ping Li
- Institute of Human Virology and Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China.,Program of Pathobiology, The Fifth Affiliated Hospital and Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China
| |
Collapse
|
8
|
Bentley K, Cook JP, Tuplin AK, Evans DJ. Structural and functional analysis of the roles of the HCV 5' NCR miR122-dependent long-range association and SLVI in genome translation and replication. PeerJ 2018; 6:e5870. [PMID: 30416884 PMCID: PMC6225842 DOI: 10.7717/peerj.5870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 09/30/2018] [Indexed: 11/29/2022] Open
Abstract
The hepatitis C virus RNA genome possesses a variety of conserved structural elements, in both coding and non-coding regions, that are important for viral replication. These elements are known or predicted to modulate key life cycle events, such as translation and genome replication, some involving conformational changes induced by long-range RNA–RNA interactions. One such element is SLVI, a stem-loop (SL) structure located towards the 5′ end of the core protein-coding region. This element forms an alternative RNA–RNA interaction with complementary sequences in the 5′ untranslated regions that are independently involved in the binding of the cellular microRNA 122 (miR122). The switch between ‘open’ and ‘closed’ structures involving SLVI has previously been proposed to modulate translation, with lower translation efficiency associated with the ‘closed’ conformation. In the current study, we have used selective 2′-hydroxyl acylation analysed by primer extension to validate this RNA–RNA interaction in the absence and presence of miR122. We show that the long-range association (LRA) only forms in the absence of miR122, or otherwise requires the blocking of miR122 binding combined with substantial disruption of SLVI. Using site-directed mutations introduced to promote open or closed conformations of the LRA we demonstrate no correlation between the conformation and the translation phenotype. In addition, we observed no influence on virus replication compared to unmodified genomes. The presence of SLVI is well-documented to suppress translation, but these studies demonstrate that this is not due to its contribution to the LRA. We conclude that, although there are roles for SLVI in translation, the LRA is not a riboswitch regulating the translation and replication phenotypes of the virus.
Collapse
Affiliation(s)
- Kirsten Bentley
- BSRC and School of Biology, University of St Andrews, St Andrews, UK
| | - Jonathan P Cook
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Andrew K Tuplin
- The Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - David J Evans
- BSRC and School of Biology, University of St Andrews, St Andrews, UK
| |
Collapse
|
9
|
Mutational Analysis of the Bovine Hepacivirus Internal Ribosome Entry Site. J Virol 2018; 92:JVI.01974-17. [PMID: 29769341 DOI: 10.1128/jvi.01974-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 05/11/2018] [Indexed: 12/19/2022] Open
Abstract
In recent years, hepatitis C virus (HCV)-related viruses were identified in several species, including dogs, horses, bats, and rodents. In addition, a novel virus of the genus Hepacivirus has been discovered in bovine samples and was termed bovine hepacivirus (BovHepV). Prediction of the BovHepV internal ribosome entry site (IRES) structure revealed strong similarities to the HCV IRES structure comprising domains II, IIIabcde, pseudoknot IIIf, and IV with the initiation codon AUG. Unlike HCV, only one microRNA-122 (miR-122) binding site could be identified in the BovHepV 5' nontranslated region. In this study, we analyzed the necessity of BovHepV IRES domains to initiate translation and investigated possible interactions between the IRES and core coding sequences by using a dual luciferase reporter assay. Our results suggest that such long-range interactions within the viral genome can affect IRES-driven translation. Moreover, the significance of a possible miR-122 binding to the BovHepV IRES was investigated. When analyzing translation in human Huh-7 cells with large amounts of endogenous miR-122, introduction of point mutations to the miR-122 binding site resulted in reduced translation efficiency. Similar results were observed in HeLa cells after substitution of miR-122. Nevertheless, the absence of pronounced effects in a bovine hepatocyte cell line expressing hardly any miR-122 as well suggests additional functions of this host factor in virus replication.IMPORTANCE Several members of the family Flaviviridae, including HCV, have adapted cap-independent translation strategies to overcome canonical eukaryotic translation pathways and use cis-acting RNA-elements, designated viral internal ribosome entry sites (IRES), to initiate translation. Although novel hepaciviruses have been identified in different animal species, only limited information is available on their biology on molecular level. Therefore, our aim was a fundamental analysis of BovHepV IRES functions. The findings which show that functional IRES elements are also crucial for BovHepV translation expand our knowledge on molecular mechanism of hepacivirus propagation. We also studied the possible effects of one major host factor implicated in HCV pathogenesis, miR-122. The results of mutational analyses suggested that miR-122 enhances virus translation mediated by BovHepV IRES.
Collapse
|
10
|
Identification of nucleotides in the 5'UTR and amino acids substitutions that are essential for the infectivity of 5'UTR-NS5A recombinant of hepatitis C virus genotype 1b (strain Con1). Virology 2018; 518:253-263. [PMID: 29549787 DOI: 10.1016/j.virol.2018.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 02/27/2018] [Accepted: 03/05/2018] [Indexed: 12/19/2022]
Abstract
Genotype 1b strain Con1 represents an important reference in the study of hepatitis C virus (HCV). Here, we aimed to develop an advanced infectious Con1 recombinant. We found that previously identified mutations A1226G/F1464L/A1672S/Q1773H permitted culture adaption of Con1 Core-NS5A (C-5A) recombinant containing 5'UTR and NS5B-3'UTR from JFH1 (genotype 2a), thus acquired additional mutations L725H/F886L/D2415G. C-5A containing all seven mutations (C-5A_7m) replicated efficiently in Huh7.5 and Huh7.5.1 cells and had an increased infectivity in SEC14L2-expressing Huh7.5.1 cells. Incorporation of Con1 NS5B was deleterious to C-5A_7m, however Con1 5'UTR was permissive but attenuated the virus. Nucleotides G1, A4, and G35 primarily accounted for the viral attenuation without affecting RNA translation. C-5A_7m was inhibited dose-dependently by simeprevir and daclatasvir, and substitutions at A4, A29, A34, and G35 conferred resistance to miR-122 antagonism. The novel Con1 5'UTR-NS5A recombinant, adaptive mutations, and critical nucleotides described here will facilitate future studies of HCV culture systems and virus-host interaction.
Collapse
|
11
|
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: 4.4] [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.
Collapse
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
| |
Collapse
|
12
|
Ventura M, Martin L, Jaubert C, Andréola ML, Masante C. Hepatitis C virus intragenomic interactions are modulated by the SLVI RNA structure of the core coding sequence. J Gen Virol 2017; 98:633-642. [PMID: 28141507 DOI: 10.1099/jgv.0.000719] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Affiliation(s)
- Michel Ventura
- Fédération de Recherche "TransbioMed", Bordeaux, France
- CNRS UMR 5234, Laboratoire MFP, Université de Bordeaux, Bordeaux F-33076, France
| | - Lucie Martin
- CNRS UMR 5234, Laboratoire MFP, Université de Bordeaux, Bordeaux F-33076, France
- Fédération de Recherche "TransbioMed", Bordeaux, France
| | - Chloé Jaubert
- CNRS UMR 5234, Laboratoire MFP, Université de Bordeaux, Bordeaux F-33076, France
- Fédération de Recherche "TransbioMed", Bordeaux, France
| | - Marie-Line Andréola
- CNRS UMR 5234, Laboratoire MFP, Université de Bordeaux, Bordeaux F-33076, France
- Fédération de Recherche "TransbioMed", Bordeaux, France
| | - Cyril Masante
- CNRS UMR 5234, Laboratoire MFP, Université de Bordeaux, Bordeaux F-33076, France
- Fédération de Recherche "TransbioMed", Bordeaux, France
| |
Collapse
|
13
|
Zhang H, Ng MY, Chen Y, Cooperman BS. Kinetics of initiating polypeptide elongation in an IRES-dependent system. eLife 2016; 5. [PMID: 27253065 PMCID: PMC4963199 DOI: 10.7554/elife.13429] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 06/01/2016] [Indexed: 11/13/2022] Open
Abstract
The intergenic IRES of Cricket Paralysis Virus (CrPV-IRES) forms a tight complex with 80S ribosomes capable of initiating the cell-free synthesis of complete proteins in the absence of initiation factors. Such synthesis raises the question of what effect the necessary IRES dissociation from the tRNA binding sites, and ultimately from all of the ribosome, has on the rates of initial peptide elongation steps as nascent peptide is formed. Here we report the first results measuring rates of reaction for the initial cycles of IRES-dependent elongation. Our results demonstrate that 1) the first two cycles of elongation proceed much more slowly than subsequent cycles, 2) these reduced rates arise from slow pseudo-translocation and translocation steps, and 3) the retarding effect of ribosome-bound IRES on protein synthesis is largely overcome following translocation of tripeptidyl-tRNA. Our results also provide a straightforward approach to detailed mechanistic characterization of many aspects of eukaryotic polypeptide elongation.
Collapse
Affiliation(s)
- Haibo Zhang
- Department of Chemistry, University of Pennsylvania, Philadelphia, United States
| | - Martin Y Ng
- Department of Chemistry, University of Pennsylvania, Philadelphia, United States
| | - Yuanwei Chen
- Department of Chemistry, University of Pennsylvania, Philadelphia, United States
| | - Barry S Cooperman
- Department of Chemistry, University of Pennsylvania, Philadelphia, United States
| |
Collapse
|
14
|
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: 4.7] [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.
Collapse
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
| |
Collapse
|
15
|
Mutations of the SL2 dimerization sequence of the hepatitis C genome abrogate viral replication. Cell Mol Life Sci 2015; 72:3375-85. [PMID: 25822205 PMCID: PMC7079775 DOI: 10.1007/s00018-015-1893-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/03/2015] [Accepted: 03/20/2015] [Indexed: 12/31/2022]
Abstract
Stem-loop SL2 is a self-interacting palindromic sequence that has been identified within the hepatitis C virus genome (HCV). While, RNA dimerization of the HCV genome has been observed in vitro with short RNA sequences, the role of a putative RNA dimerization during viral replication has not been elucidated. To determine the effect of genomic dimerization on viral replication, we introduced mutations into SL2 predicted to disrupt genomic dimerization. Using surface plasmon resonance, we show that mutations within the SL2 bulge impact dimerization in vitro. Transfection of Huh7 cells with luciferase-encoding full-length genomes containing SL2 mutations abolishes viral replication. Luciferase expression indicates that viral translation is not or slightly affected and that the viral RNA is properly encapsidated. However, RT-qPCR analysis demonstrates that viral RNA synthesis is drastically decreased. In vitro synthesis experiments using the viral recombinant polymerase show that modifications of intra-molecular interactions have no effect on RNA synthesis, while impairing inter-molecular interactions decreases polymerase activity. This confirms that dimeric templates are preferentially replicated by the viral polymerase. Altogether, these results indicate that the dimerization of the HCV genomic RNA is a crucial step for the viral life cycle especially for RNA replication. RNA dimerization could explain the existence of HCV recombinants in cell culture and patients reported recently in other studies.
Collapse
|
16
|
García-Sacristán A, Moreno M, Ariza-Mateos A, López-Camacho E, Jáudenes RM, Vázquez L, Gómez J, Martín-Gago JÁ, Briones C. A magnesium-induced RNA conformational switch at the internal ribosome entry site of hepatitis C virus genome visualized by atomic force microscopy. Nucleic Acids Res 2014; 43:565-80. [PMID: 25510496 PMCID: PMC4288189 DOI: 10.1093/nar/gku1299] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The 5' untranslated region of hepatitis C virus (HCV) genomic RNA contains an internal ribosome entry site (IRES) element, composed of domains II-IV, which is required for cap-independent translation initiation. Little information on the 3D structure of the whole functional HCV IRES is still available. Here, we use atomic force microscopy to visualize the HCV IRES conformation in its natural sequence context, which includes the upstream domain I and the essential, downstream domains V and VI. The 574 nt-long molecule analyzed underwent an unexpected, Mg(2+)-induced switch between two alternative conformations: from 'open', elongated morphologies at 0-2 mM Mg(2+) concentration to a 'closed', comma-shaped conformation at 4-6 mM Mg(2+). This sharp transition, confirmed by gel-shift analysis and partial RNase T1 cleavage, was hindered by the microRNA miR-122. The comma-shaped IRES-574 molecules visualized at 4-6 mM Mg(2+) in the absence of miR-122 showed two arms. Our data support that the first arm would contain domain III, while the second one would be composed of domains (I-II)+(V-VI) thanks to a long-range RNA interaction between the I-II spacer and the basal region of domain VI. This reinforces the previously described structural continuity between the HCV IRES and its flanking domains I, V and VI.
Collapse
Affiliation(s)
- Ana García-Sacristán
- Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Madrid 28850, Spain Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Spain
| | - Miguel Moreno
- Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Madrid 28850, Spain
| | - Ascensión Ariza-Mateos
- Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Spain Laboratory of RNA Archaeology, Instituto de Parasitología y Biomedicina 'López-Neyra' (CSIC), Parque Tecnológico Ciencias de la Salud, Armilla, Granada 18016, Spain
| | - Elena López-Camacho
- Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Madrid 28850, Spain Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, Madrid 28049, Spain
| | - Rosa M Jáudenes
- Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Madrid 28850, Spain
| | - Luis Vázquez
- Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, Madrid 28049, Spain
| | - Jordi Gómez
- Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Spain Laboratory of RNA Archaeology, Instituto de Parasitología y Biomedicina 'López-Neyra' (CSIC), Parque Tecnológico Ciencias de la Salud, Armilla, Granada 18016, Spain
| | - José Ángel Martín-Gago
- Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Madrid 28850, Spain Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, Madrid 28049, Spain
| | - Carlos Briones
- Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Madrid 28850, Spain Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Spain
| |
Collapse
|
17
|
Khawaja A, Vopalensky V, Pospisek M. Understanding the potential of hepatitis C virus internal ribosome entry site domains to modulate translation initiation via their structure and function. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 6:211-24. [PMID: 25352252 PMCID: PMC4361049 DOI: 10.1002/wrna.1268] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Revised: 08/31/2014] [Accepted: 09/02/2014] [Indexed: 12/16/2022]
Abstract
Translation initiation in the hepatitis C virus (HCV) occurs through a cap-independent mechanism that involves an internal ribosome entry site (IRES) capable of interacting with and utilizing the eukaryotic translational machinery. In this review, we focus on the structural configuration of the different HCV IRES domains and the impact of IRES primary sequence variations on secondary structure conservation and function. In some cases, multiple mutations, even those scattered across different domains, led to restoration of the translational activity of the HCV IRES, although the individual occurrences of these mutations were found to be deleterious. We propose that such observation may be attributed to probable long-range inter- and/or intra-domain functional interactions. The precise functioning of the HCV IRES requires the specific interaction of its domains with ribosomal subunits and a subset of eukaryotic translation initiation factors (eIFs). The structural conformation, sequence preservation and variability, and translational machinery association with the HCV IRES regions are also thoroughly discussed, along with other factors that can affect and influence the formation of translation initiation complexes. WIREs RNA 2015, 6:211–224. doi: 10.1002/wrna.1268
Collapse
Affiliation(s)
- Anas Khawaja
- Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Prague 2, Czech Republic
| | | | | |
Collapse
|
18
|
Romero-López C, Berzal-Herranz A. Structure-function relationship in viral RNA genomes: The case of hepatitis C virus. World J Med Genet 2014; 4:6-18. [DOI: 10.5496/wjmg.v4.i2.6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 01/23/2014] [Accepted: 04/03/2014] [Indexed: 02/06/2023] Open
Abstract
The acquisition of a storage information system beyond the nucleotide sequence has been a crucial issue for the propagation and dispersion of RNA viruses. This system is composed by highly conserved, complex structural units in the genomic RNA, termed functional RNA domains. These elements interact with other regions of the viral genome and/or proteins to direct viral translation, replication and encapsidation. The genomic RNA of the hepatitis C virus (HCV) is a good model for investigating about conserved structural units. It contains functional domains, defined by highly conserved structural RNA motifs, mostly located in the 5’-untranslatable regions (5’UTRs) and 3’UTR, but also occupying long stretches of the coding sequence. Viral translation initiation is mediated by an internal ribosome entry site located at the 5’ terminus of the viral genome and regulated by distal functional RNA domains placed at the 3’ end. Subsequent RNA replication strongly depends on the 3’UTR folding and is also influenced by the 5’ end of the HCV RNA. Further increase in the genome copy number unleashes the formation of homodimers by direct interaction of two genomic RNA molecules, which are finally packed and released to the extracellular medium. All these processes, as well as transitions between them, are controlled by structural RNA elements that establish a complex, direct and long-distance RNA-RNA interaction network. This review summarizes current knowledge about functional RNA domains within the HCV RNA genome and provides an overview of the control exerted by direct, long-range RNA-RNA contacts for the execution of the viral cycle.
Collapse
|
19
|
Karamichali E, Foka P, Tsitoura E, Kalliampakou K, Kazazi D, Karayiannis P, Georgopoulou U, Mavromara P. HCV NS5A co-operates with PKR in modulating HCV IRES-dependent translation. INFECTION GENETICS AND EVOLUTION 2014; 26:113-22. [PMID: 24815730 DOI: 10.1016/j.meegid.2014.04.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 04/15/2014] [Accepted: 04/19/2014] [Indexed: 12/11/2022]
Abstract
Translation initiation of the Hepatitis C virus (HCV) genome is driven by an internal ribosome entry site (IRES), located within the 5' non-coding region. Several studies have suggested that different cellular non canonical proteins or viral proteins can regulate the HCV IRES activity. However, the role of the viral proteins on HCV translation remains controversial. In this report, we confirmed previous studies showing that NS5A down-regulates IRES activity in HepG2 but not in Huh7 cells suggesting that the NS5A effect on HCV IRES is cell-type dependent. Additionally, we provide strong evidence that activated PKR up-regulates the IRES activity while silencing of endogenous PKR had the opposite effect. Furthermore, we present data indicating that the NS5A-mediated inhibitory effect on IRES-dependent translation could be linked with the PKR inactivation. Finally, we show that NS5A from GBV-C but not from GBV-B down-regulates HCV IRES activity in the absence or the presence of PKR over expression. Notably, HCV and GBV-C but not GBV-B NS5A contains a previously identified PKR interacting protein domain.
Collapse
Affiliation(s)
- Eirini Karamichali
- Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece; University of Patras, School of Health Sciences, Department of Pharmacy, Greece
| | - Pelagia Foka
- Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece
| | - Eliza Tsitoura
- Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece
| | | | - Dorothea Kazazi
- Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece
| | - Peter Karayiannis
- Molecular Virology/Microbiology, University of Nicosia Medical School, Cyprus
| | | | - Penelope Mavromara
- Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece.
| |
Collapse
|
20
|
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: 5.6] [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.
Collapse
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:
| |
Collapse
|
21
|
|
22
|
Goergen D, Niepmann M. Stimulation of Hepatitis C Virus RNA translation by microRNA-122 occurs under different conditions in vivo and in vitro. Virus Res 2012; 167:343-52. [PMID: 22677772 DOI: 10.1016/j.virusres.2012.05.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 05/18/2012] [Accepted: 05/21/2012] [Indexed: 02/07/2023]
Abstract
Translation of the Hepatitis C Virus (HCV) positive strand RNA genome is directed by an internal ribosome entry site (IRES) in the viral RNA's 5'-untranslated region (5'-UTR). HCV propagates preferentially in the liver, and HCV translation is stimulated by the liver-specific microRNA-122 (miR-122) acting on two target sites in the 5'-UTR. This stimulation is effective in living cells containing miR-122 and also in the rabbit reticulocyte lysate in vitro-translation system after addition of miR-122. Another RNA sequence located in the Core protein coding sequence can base-pair in a long-range RNA-RNA interaction to the HCV 5'-UTR, overlapping with the miR-122 target sites and the short spacer between them, and thereby inhibits HCV translation. Here we show genetic evidence that in reticulocyte lysate single-stranded miR-122 interferes with this inhibitory long-range RNA-RNA interaction and thereby contributes to enhanced HCV translation, involving not only the 5'-seed sequence of miR-122 but also sequences at its 3'-end. Also RNA oligonucleotides shorter than a typical microRNA stimulate HCV translation, confirming that in the reticulocyte lysate the stimulation of HCV translation functions by displacement of the inhibitory long-range interaction by miR-122. In contrast, in transfected HuH-7 hepatoma cells and in HeLa cells this interference of miR-122 with the inhibitory long-range RNA-RNA interaction plays not a major role, but only duplex miR-122 RNAs of the correct length stimulate HCV translation. These results suggest that: (1) the processing of the microRNA precursors and (2) the events occurring at the HCV RNA differ between cells and reticulocyte lysate.
Collapse
Affiliation(s)
- Dagmar Goergen
- Institute of Biochemistry, Faculty of Medicine, Justus-Liebig-University, Friedrichstrasse 24, 35392 Giessen, Germany
| | | |
Collapse
|
23
|
Composition of the sequence downstream of the dengue virus 5' cyclization sequence (dCS) affects viral RNA replication. Virology 2011; 422:346-56. [PMID: 22137186 DOI: 10.1016/j.virol.2011.10.025] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 08/11/2011] [Accepted: 10/28/2011] [Indexed: 12/31/2022]
Abstract
RNA replication of dengue virus (DENV) requires an RNA-RNA mediated circularization of the viral genome, which includes at least three sets of complementary RNA sequences on both ends of the genome. The 5' and the 3' untranslated regions form several additional RNA elements that are involved in regulation of translation and required for RNA replication. Communication between the genomic termini results in a structural reorganization of the RNA elements, forming a functional RNA panhandle structure. Here we report that the sequence composition downstream of the 5' CS element in the capsid gene, designated as downstream CS (dCS) sequence - but not the capsid protein - also influences the ability of the viral genome to circularize and hence replicate by modulating the topology of the 5' end. These results provide insights for the design of reporter sub-genomic and genomic mosquito-borne flavivirus constructs and contribute to the understanding of viral RNA replication.
Collapse
|
24
|
Abstract
Hepatitis C viral protein translation occurs in a cap-independent manner through the use of an internal ribosomal entry site (IRES) present within the viral 5'-untranslated region. The IRES is composed of highly conserved structural domains that directly recruit the 40S ribosomal subunit to the viral genomic RNA. This frees the virus from relying on a large number of translation initiation factors that are required for cap-dependent translation, conferring a selective advantage to the virus especially in times when the availability of such factors is low. Although the mechanism of translation initiation on the Hepatitis C virus (HCV) IRES is well established, modulation of the HCV IRES activity by both cellular and viral factors is not well understood. As the IRES is essential in the HCV life cycle and as such remains well conserved in an otherwise highly heterogenic virus, the process of HCV protein translation represents an attractive target in the development of novel antivirals. This review will focus on the mechanisms of HCV protein translation and how this process is postulated to be modulated by cis-acting viral factors, as well as trans-acting viral and cellular factors. Numerous therapeutic approaches investigated in targeting HCV protein translation for the development of novel antivirals will also be discussed.
Collapse
Affiliation(s)
- Brett Hoffman
- Vaccine and Infectious Disease Organization/International Vaccine Center, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | | |
Collapse
|
25
|
Li YP, Ramirez S, Gottwein JM, Bukh J. Non-genotype-specific role of the hepatitis C virus 5' untranslated region in virus production and in inhibition by interferon. Virology 2011; 421:222-34. [PMID: 22029937 DOI: 10.1016/j.virol.2011.10.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 06/15/2011] [Accepted: 10/03/2011] [Indexed: 12/18/2022]
Abstract
The 5' untranslated region (5'UTR) of hepatitis C virus (HCV) is structured into four domains (I-IV) with numerous genotype-specific nucleotides. It is unknown whether the polymorphisms confer genotype-specific functions to the 5'UTR. Using viable JFH1-based Core-NS2 recombinants, we developed and characterized HCV genotypes 1-7 recombinants with highly diverse 5'UTRs (genotypes 1a and 3a), 2a recombinants (J6/JFH1) with 5'UTR of genotypes 1-6 or with heterotypic chimeric (1a/3a and 3a/1a) 5'UTR domains I, II or III, and 1a recombinants with 5'UTR domain I of genotypes 1-6. All were fully functional in Huh7.5 cells; therefore, the 5'UTR apparently functions in a non-genotype-specific manner in HCV production in vitro. However, adenine at the 5'-terminus was required. We demonstrated that J6/JFH1 with 5'UTR of genotypes 1-6 responded similarly to interferon-α2b. This study provides novel insight into the role of the 5'UTR in the HCV life cycle and facilitates HCV basic research and testing of 5'UTR-targeting antivirals.
Collapse
Affiliation(s)
- Yi-Ping Li
- Copenhagen Hepatitis C Program, Department of Infectious Diseases and Clinical Research Centre, Copenhagen University Hospital, Hvidovre, Denmark
| | | | | | | |
Collapse
|
26
|
Abstract
About 170 million persons are infected with hepatitis C virus (HCV) around the world, and nearly 80% of infected patients develop chronic liver disease that may eventually lead to liver cirrhosis or hepatocellular carcinoma. The mechanisms underlying the life cycle of HCV in the host are still largely unknown and the efforts made by researchers have been hampered by the absence of a robust system reproducing HCV infection. Moreover, there are no effective vaccines or drugs available to defend or exclude viruses because of frequent viral mutation. In 2005, several research groups have successfully established cell culture systems for HCV, pushing the basic research on HCV to a new stage. This paper will focus on HCV genome diversity, progress in culture models, HCV life cycle, and protein function to highlight the mechanism of HCV infection.
Collapse
|
27
|
Roberts APE, Lewis AP, Jopling CL. miR-122 activates hepatitis C virus translation by a specialized mechanism requiring particular RNA components. Nucleic Acids Res 2011; 39:7716-29. [PMID: 21653556 PMCID: PMC3177192 DOI: 10.1093/nar/gkr426] [Citation(s) in RCA: 173] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In animals, microRNAs (miRNAs) generally repress gene expression by binding to sites in the 3′-untranslated region (UTR) of target mRNAs. miRNAs have also been reported to repress or activate gene expression by binding to 5′-UTR sites, but the extent of such regulation and the factors that govern these different responses are unknown. Liver-specific miR-122 binds to sites in the 5′-UTR of hepatitis C virus (HCV) RNA and positively regulates the viral life cycle, in part by stimulating HCV translation. Here, we characterize the features that allow miR-122 to activate translation via the HCV 5′-UTR. We find that this regulation is a highly specialized process that requires uncapped RNA, the HCV internal ribosome entry site (IRES) and the 3′ region of miR-122. Translation activation does not involve a previously proposed structural transition in the HCV IRES and is mediated by Argonaute proteins. This study provides an important insight into the requirements for the miR-122–HCV interaction, and the broader consequences of miRNAs binding to 5′-UTR sites.
Collapse
Affiliation(s)
- Ashley P E Roberts
- Centre for Biomolecular Sciences, University of Nottingham, Nottingham, UK
| | | | | |
Collapse
|
28
|
Villordo SM, Alvarez DE, Gamarnik AV. A balance between circular and linear forms of the dengue virus genome is crucial for viral replication. RNA (NEW YORK, N.Y.) 2010; 16:2325-2335. [PMID: 20980673 PMCID: PMC2995394 DOI: 10.1261/rna.2120410] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 09/08/2010] [Indexed: 05/30/2023]
Abstract
The plasticity of viral plus strand RNA genomes is fundamental for the multiple functions of these molecules. Local and long-range RNA-RNA interactions provide the scaffold for interacting proteins of the translation, replication, and encapsidation machinery. Using dengue virus as a model, we investigated the relevance of the interplay between two alternative conformations of the viral genome during replication. Flaviviruses require long-range RNA-RNA interactions and genome cyclization for RNA synthesis. Here, we define a sequence present in the viral 3'UTR that overlaps two mutually exclusive structures. This sequence can form an extended duplex by long-range 5'-3' interactions in the circular conformation of the RNA or fold locally into a small hairpin (sHP) in the linear form of the genome. A mutational analysis of the sHP structure revealed an absolute requirement of this element for viral viability, suggesting the need of a linear conformation of the genome. Viral RNA replication showed high vulnerability to changes that alter the balance between circular and linear forms of the RNA. Mutations that shift the equilibrium toward the circular or the linear conformation of the genome spontaneously revert to sequences with different mutations that tend to restore the relative stability of the two competing structures. We propose a model in which the viral genome exists in at least two alternative conformations and the balance between these two states is critical for infectivity.
Collapse
|
29
|
Liu Y, Wimmer E, Paul AV. Cis-acting RNA elements in human and animal plus-strand RNA viruses. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2009; 1789:495-517. [PMID: 19781674 PMCID: PMC2783963 DOI: 10.1016/j.bbagrm.2009.09.007] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Revised: 09/09/2009] [Accepted: 09/13/2009] [Indexed: 02/08/2023]
Abstract
The RNA genomes of plus-strand RNA viruses have the ability to form secondary and higher-order structures that contribute to their stability and to their participation in inter- and intramolecular interactions. Those structures that are functionally important are called cis-acting RNA elements because their functions cannot be complemented in trans. They can be involved not only in RNA/RNA interactions but also in binding of viral and cellular proteins during the complex processes of translation, RNA replication and encapsidation. Most viral cis-acting RNA elements are located in the highly structured 5'- and 3'-nontranslated regions of the genomes but sometimes they also extend into the adjacent coding sequences. In addition, some cis-acting RNA elements are embedded within the coding sequences far away from the genomic ends. Although the functional importance of many of these structures has been confirmed by genetic and biochemical analyses, their precise roles are not yet fully understood. In this review we have summarized what is known about cis-acting RNA elements in nine families of human and animal plus-strand RNA viruses with an emphasis on the most thoroughly characterized virus families, the Picornaviridae and Flaviviridae.
Collapse
Affiliation(s)
- Ying Liu
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11790, USA
| | | | | |
Collapse
|
30
|
Romero-López C, Berzal-Herranz A. A long-range RNA-RNA interaction between the 5' and 3' ends of the HCV genome. RNA (NEW YORK, N.Y.) 2009; 15:1740-1752. [PMID: 19605533 PMCID: PMC2743058 DOI: 10.1261/rna.1680809] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Accepted: 06/04/2009] [Indexed: 02/05/2023]
Abstract
The RNA genome of the hepatitis C virus (HCV) contains multiple conserved structural cis domains that direct protein synthesis, replication, and infectivity. The untranslatable regions (UTRs) play essential roles in the HCV cycle. Uncapped viral RNAs are translated via an internal ribosome entry site (IRES) located at the 5' UTR, which acts as a scaffold for recruiting multiple protein factors. Replication of the viral genome is initiated at the 3' UTR. Bioinformatics methods have identified other structural RNA elements thought to be involved in the HCV cycle. The 5BSL3.2 motif, which is embedded in a cruciform structure at the 3' end of the NS5B coding sequence, contributes to the three-dimensional folding of the entire 3' end of the genome. It is essential in the initiation of replication. This paper reports the identification of a novel, strand-specific, long-range RNA-RNA interaction between the 5' and 3' ends of the genome, which involves 5BSL3.2 and IRES motifs. Mutants harboring substitutions in the apical loop of domain IIId or in the internal loop of 5BSL3.2 disrupt the complex, indicating these regions are essential in initiating the kissing interaction. No complex was formed when the UTRs of the related foot and mouth disease virus were used in binding assays, suggesting this interaction is specific for HCV sequences. The present data firmly suggest the existence of a higher-order structure that may mediate a protein-independent circularization of the HCV genome. The 5'-3' end bridge may have a role in viral translation modulation and in the switch from protein synthesis to RNA replication.
Collapse
Affiliation(s)
- Cristina Romero-López
- Departamento de Biología Molecular, Instituto de Parasitología y Biomedicina López-Neyra, Consejo Superior de Investigaciones Científicas, Armilla, 18100 Granada, Spain
| | | |
Collapse
|
31
|
Hepatitis C virus NS2/3 protease regulates HCV IRES-dependent translation and NS5B RdRp activity. Arch Virol 2009; 154:1465-73. [PMID: 19688585 DOI: 10.1007/s00705-009-0469-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2009] [Accepted: 07/09/2009] [Indexed: 01/01/2023]
Abstract
Chronic hepatitis C virus (HCV) infection often leads to liver cancer. NS2/3 protease is the first of two virally encoded proteases required for HCV polyprotein processing. In this report, we investigated the function of NS2/3 protease on HCV replication and translation. Cells transfected with plasmids encoding wild-type or mutant NS2/3 and a dual-luciferase reporter construct containing an HCV internal ribosome entry site (IRES) were used to examine the effect of NS2/3 protease on translation of HCV RNA. Cells transfected with plasmids encoding wild-type or mutant NS2/3, pcDNA-NS5B and a reporter plasmid were used to examine the effect of NS2/3 protease on HCV replication. The results showed that both autocleavage processing and the uncleaved form of NS2/3 protease specifically decrease HCV IRES-directed translation, while the uncleaved form of NS2/3 protease decreases HCV NS5B RdRp activity (replication), indicating that autoregulation by NS2/3 protease of HCV replication and translation may play an important role in persistent HCV infection.
Collapse
|
32
|
Díaz-Toledano R, Ariza-Mateos A, Birk A, Martínez-García B, Gómez J. In vitro characterization of a miR-122-sensitive double-helical switch element in the 5' region of hepatitis C virus RNA. Nucleic Acids Res 2009; 37:5498-510. [PMID: 19578061 PMCID: PMC2760801 DOI: 10.1093/nar/gkp553] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
It has been proposed that the hepatitis C virus (HCV) internal ribosome entry site (IRES) resides within a locked conformation, owing to annealing of its immediate flanking sequences. In this study, structure probing using Escherichia coli dsRNA-specific RNase III and other classical tools showed that this region switches to an open conformation triggered by the liver-specific microRNA, miR-122. This structural transition, observed in vitro, may be the mechanistic basis for the involvement of downstream IRES structural domain VI in translation, as well as providing a role of liver-specific miR-122 in HCV infection. In addition, the induced RNA switching at the 5′ untranslated region could ultimately represent a new mechanism of action of micro-RNAs.
Collapse
Affiliation(s)
- Rosa Díaz-Toledano
- Laboratorio de Arqueología del RNA, Departamento de Bioquímica y Biología Molecular, Instituto de Parasitología y Biomedicina López Neyra Armilla, 18100 Granada, Spain
| | | | | | | | | |
Collapse
|
33
|
Wu B, Pogany J, Na H, Nicholson BL, Nagy PD, White KA. A discontinuous RNA platform mediates RNA virus replication: building an integrated model for RNA-based regulation of viral processes. PLoS Pathog 2009; 5:e1000323. [PMID: 19266082 PMCID: PMC2648310 DOI: 10.1371/journal.ppat.1000323] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Accepted: 02/03/2009] [Indexed: 01/01/2023] Open
Abstract
Plus-strand RNA viruses contain RNA elements within their genomes that mediate a variety of fundamental viral processes. The traditional view of these elements is that of local RNA structures. This perspective, however, is changing due to increasing discoveries of functional viral RNA elements that are formed by long-range RNA–RNA interactions, often spanning thousands of nucleotides. The plus-strand RNA genomes of tombusviruses exemplify this concept by possessing different long-range RNA–RNA interactions that regulate both viral translation and transcription. Here we report that a third fundamental tombusvirus process, viral genome replication, requires a long-range RNA–based interaction spanning ∼3000 nts. In vivo and in vitro analyses suggest that the discontinuous RNA platform formed by the interaction facilitates efficient assembly of the viral RNA replicase. This finding has allowed us to build an integrated model for the role of global RNA structure in regulating the reproduction of a eukaryotic RNA virus, and the insights gained have extended our understanding of the multifunctional nature of viral RNA genomes. Plus-strand (i.e. messenger-sensed) RNA viruses are responsible for significant diseases in plants and animals. The single-stranded RNA genomes of these viruses serve as templates for translation of viral proteins and perform other essential functions that generally involve local RNA structures, such as RNA hairpins. Interestingly, plant tombusviruses utilize a number of long-range intra-genomic RNA–RNA interactions to regulate important events during infection of their hosts, i.e. viral translation and transcription. Here, we report that an additional essential tombusvirus process, viral RNA replication, also requires a long-range RNA–RNA interaction. Our analyses indicate a role for this RNA–based interaction in the assembly of the viral replicase, which is responsible for executing viral RNA synthesis. This information was used to generate a comprehensive higher-order RNA structural model for functional long-range interactions in the genome of this eukaryotic RNA virus. The model highlights a critical role for global RNA structure in multiple viral processes that are necessary for successful infection of hosts.
Collapse
Affiliation(s)
- Baodong Wu
- Department of Biology, York University, Toronto, Ontario, Canada
| | | | | | | | | | | |
Collapse
|
34
|
Hepatitis C virus (HCV) NS2 protein up-regulates HCV IRES-dependent translation and down-regulates NS5B RdRp activity. Arch Virol 2008; 153:1991-7. [PMID: 18853100 DOI: 10.1007/s00705-008-0198-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Accepted: 08/19/2008] [Indexed: 12/25/2022]
Abstract
Chronic hepatitis C virus (HCV) infection often leads to liver cancer. The HCV NS2 protein is a hydrophobic transmembrane protein that associates with several cellular proteins in mammalian cells. In this report, we investigated the function of NS2 protein on HCV replication and translation by using a transient cell-based expression system. Cells co-transfected with pcDNA3.1 (-)-NS2 and the dual-luciferase reporter construct containing the HCV IRES were used to detect the effect of NS2 protein on HCV translation. Cells co-transfected with pcDNA3.1(-)-NS2, pcDNA-NS5B and a reporter plasmid were used to detect the effect of NS2 protein on HCV replication. The results showed that HCV NS2 protein up-regulated HCV IRES-dependent translation in a specific and dose-dependent manner in Huh7 cells but not in HeLa and HepG2 cells, and NS2 protein inhibited NS5B RdRp activity in a dose-independent manner in all three cell lines. These findings may suggest a novel mechanism by which HCV modulates its NS5B replication and IRES-dependent translation and facilitates virus persistence.
Collapse
|
35
|
Role of the hepatitis C virus core+1 open reading frame and core cis-acting RNA elements in viral RNA translation and replication. J Virol 2008; 82:11503-15. [PMID: 18799568 DOI: 10.1128/jvi.01640-08] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Four conserved RNA stem-loop structures designated SL47, SL87, SL248, and SL443 have been predicted in the hepatitis C virus (HCV) core encoding region. Moreover, alternative translation products have been detected from a reading frame overlapping the core gene (core+1/ARFP/F). To study the importance of the core+1 frame and core-RNA structures for HCV replication in cell culture and in vivo, a panel of core gene silent mutations predicted to abolish core+1 translation and affecting core-RNA stem-loops were introduced into infectious-HCV genomes of the isolate JFH1. A mutation disrupting translation of all known forms of core+1 and affecting SL248 did not alter virus production in Huh7 cells and in mice xenografted with human liver tissue. However, a combination of mutations affecting core+1 at multiple codons and at the same time, SL47, SL87, and SL248, delayed RNA replication kinetics and substantially reduced virus titers. The in vivo infectivity of this mutant was impaired, and in virus genomes recovered from inoculated mice, SL87 was restored by reversion and pseudoreversion. Mutations disrupting the integrity of this stem-loop, as well as that of SL47, were detrimental for virus viability, whereas mutations disrupting SL248 and SL443 had no effect. This phenotype was not due to impaired RNA stability but to reduced RNA translation. Thus, SL47 and SL87 are important RNA elements contributing to HCV genome translation and robust replication in cell culture and in vivo.
Collapse
|
36
|
Lourenço S, Costa F, Débarges B, Andrieu T, Cahour A. Hepatitis C virus internal ribosome entry site-mediated translation is stimulated by cis-acting RNA elements and trans-acting viral factors. FEBS J 2008; 275:4179-97. [DOI: 10.1111/j.1742-4658.2008.06566.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
|
37
|
Wolf M, Dimitrova M, Baumert TF, Schuster C. The major form of hepatitis C virus alternate reading frame protein is suppressed by core protein expression. Nucleic Acids Res 2008; 36:3054-64. [PMID: 18400784 PMCID: PMC2396417 DOI: 10.1093/nar/gkn111] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Hepatitis C virus (HCV) is a human RNA virus encoding 10 proteins in a single open reading frame. In the +1 frame, an ‘alternate reading frame’ (ARF) overlaps with the core protein-encoding sequence and encodes the ARF protein (ARFP). Here, we investigated the molecular regulatory mechanisms of ARFP expression in HCV target cells. Chimeric HCV-luciferase reporter constructs derived from the infectious HCV prototype isolate H77 were transfected into hepatocyte-derived cell lines. Translation initiation was most efficient at the internal AUG codon at position 86/88, resulting in the synthesis of a truncated ARFP named 86/88ARFP. Interestingly, 86/88ARFP synthesis was markedly enhanced in constructs containing an inactivated core protein reading frame. This enhancement was reversed by co-expression of core protein in trans, demonstrating suppression of ARFP synthesis by HCV core protein. In conclusion, our results indicate that translation of ARFP occurs mainly by alternative internal initiation at position 86/88 and is regulated by HCV core protein expression. The suppression of ARFP translation by HCV core protein suggests that ARFP expression is inversely linked to the level of viral replication. These findings define key mechanisms regulating ARFP expression and set the stage for further studies addressing the function of ARFP within the viral life cycle.
Collapse
Affiliation(s)
- Marie Wolf
- Inserm, U748, Université Louis Pasteur, Strasbourg and Service d'Hépatogastroentérologie, Hôpitaux Universitaires de Strasbourg, F-67000, France
| | | | | | | |
Collapse
|
38
|
Xiao M, Bai Y, Xu H, Geng X, Chen J, Wang Y, Chen J, Li B. Effect of NS3 and NS5B proteins on classical swine fever virus internal ribosome entry site-mediated translation and its host cellular translation. J Gen Virol 2008; 89:994-999. [DOI: 10.1099/vir.0.83341-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
A full-length NS3 (NS3F) and a truncated NS3 protein (NS3H) with an RNA helicase domain possess RNA helicase activity. Using an in vitro system with a monocistronic reporter RNA or DNA, containing the CSFV 5′-UTR, we observed that both NS3F and NS3H enhanced internal ribosome entry site (IRES)-mediated and cellular translation in a dose-dependent manner, but NS3 protease (NS3P) that lacks a helicase domain did not. NS3F was stronger than NS3H in promoting both translations. These results showed that viral RNA helicase could promote viral and cellular translation, and higher RNA helicase activity might be more efficient. The NS5B protein, the viral replicase, did not significantly affect the IRES-directed or cellular translation alone. NS5B significantly enhanced the stimulative effect of NS3F on both IRES-mediated and cellular translation, but did not affect that of NS3H or NS3P. This suggests that NS5B and NS3 interact via the protease domain during the enhancement of translation.
Collapse
Affiliation(s)
- Ming Xiao
- College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, PR China
| | - Yan Bai
- College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, PR China
| | - Hui Xu
- College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, PR China
| | - Xiaolu Geng
- 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
| | - Yujing Wang
- College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, PR China
| | - Jiakuan Chen
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, The Institute of Biodiversity Science, Fudan University, Shanghai 200433, PR China
| | - Bo Li
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, The Institute of Biodiversity Science, Fudan University, Shanghai 200433, PR China
| |
Collapse
|
39
|
Abstract
Hepatitis C virus (HCV) is a small, enveloped RNA virus that is often capable of establishing a persistent infection, which may lead to chronic liver disease, cirrhosis, hepatocellular carcinoma, and eventually death. For more than 20 years, hepatitis C patients have been treated with interferon-alpha (IFN-α). Current treatment usually consists of polyethylene glycol-conjugated IFN-α that is combined with ribavirin, but even the most advanced IFN-based therapies are still ineffective in eliminating the virus from a large proportion of individuals. Therefore, a better understanding of the IFN-induced innate immune response is urgently needed. By using selectable self-replicating RNAs (replicons) and, more recently, recombinant full-length genomes, many groups have tried to elucidate the mechanism(s) by which IFNs inhibit HCV replication. This chapter attempts to summarize the current state of knowledge in this interesting field of HCV research.
Collapse
|
40
|
Uncoupling RNA virus replication from transcription via the polymerase: functional and evolutionary insights. EMBO J 2007; 26:5120-30. [PMID: 18034156 DOI: 10.1038/sj.emboj.7601931] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 10/29/2007] [Indexed: 01/11/2023] Open
Abstract
Many eukaryotic positive-strand RNA viruses transcribe subgenomic (sg) mRNAs that are virus-derived messages that template the translation of a subset of viral proteins. Currently, the premature termination (PT) mechanism of sg mRNA transcription, a process thought to operate in a variety of viruses, is best understood in tombusviruses. The viral RNA elements involved in regulating this mechanism have been well characterized in several systems; however, no corresponding protein factors have been identified yet. Here we show that tombusvirus genome replication can be effectively uncoupled from sg mRNA transcription in vivo by C-terminal modifications in its RNA-dependent RNA polymerase (RdRp). Systematic analysis of the PT transcriptional pathway using viral genomes harboring mutant RdRps revealed that the C-terminus functions primarily at an early step in this mechanism by mediating both efficient and accurate production of minus-strand templates for sg mRNA transcription. Our results also suggest a simple evolutionary scheme by which the virus could gain or enhance its transcriptional activity, and define global folding of the viral RNA genome as a previously unappreciated determinant of RdRp evolution.
Collapse
|
41
|
Motazakker M, Preikschat P, Elliott J, Smith CA, Mills PR, Oien K, Spence E, Elliott RM, McCruden EAB. Translation efficiencies of the 5'-untranslated region of genotypes 1a and 3a in hepatitis C infected patients. J Med Virol 2007; 79:259-69. [PMID: 17245719 DOI: 10.1002/jmv.20794] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Differences between the translation efficiencies mediated by the 5'-untranslated regions (5'-UTR) of genotypes (gt) 1 and 3 of hepatitis C virus (HCV) have been reported but it is unknown if such differences are biologically significant. The 5'-UTR was sequenced from paired serum and liver samples from 26 patients with chronic HCV hepatitis (11 gt 1a, 15 gt 3a). To determine whether there is a consistent difference between gts 1a and 3a translation efficiency, 5'-UTR (nt 1-356) and 5'-UTR plus core (nt 1-914) sequences were cloned into bicistronic, luciferase-encoding constructs and relative translation efficiencies (RTE) measured in Huh7 cells and BHK cells. The relationships between viral load, liver biopsy Ishak scores, degree of steatosis and translational activity of the patient-derived nucleotide sequence were examined. There were no differences in 5'-UTR sequence between serum and corresponding liver samples. The mean RTE of 5'-UTR sequences from gt 3a isolates was not significantly different from gt 1a whether or not the core encoding sequence was included, although inclusion of core led to a reduction in RTE by 93-97% for both genotypes. No correlation was found between RTE and serum HCV RNA levels, liver steatosis, inflammation, or fibrosis. However, a significant correlation was found between the presence of steatosis and infection with HCV gt 3a. It is concluded that there was no difference in translation efficiencies of 5'-UTRs from patients infected with gts 1a and 3a, and translation activity measured in vitro does not correlate with viral load or severity of liver disease.
Collapse
Affiliation(s)
- M Motazakker
- Division of Infection and Immunity, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Thélu MA, Leroy V, Ramzan M, Dufeu-Duchesne T, Marche P, Zarski JP. IRES complexity before IFN-alpha treatment and evolution of the viral load at the early stage of treatment in peripheral blood mononuclear cells from chronic hepatitis C patients. J Med Virol 2007; 79:242-53. [PMID: 17245718 DOI: 10.1002/jmv.20792] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
At the early stage of treatment, IFN alpha-2a induces inhibition of HCV replication. The viral load reflects mainly the degradation rate of the viruses. However, differences in the behavior of the viral population depend on changes, which occurred in the HCV-IRES genome. In this study, cloning and sequencing strategies permitted the generation of a large number of IRES sequences from the PBMCs of 18 patients (5 women, 13 men) with chronic hepatitis C. The HCV IRES appeared to be highly conserved structurally. However, some variability was found between the different isolates obtained: 467 substitutions with a median of 7 variants/patients. No relationship was observed between pre-treatment IRES complexity and the viral load at the beginning. However, on review of the evolution of viral load in the PBMCs during the first 3 days of IFN alpha-2a treatment, patients could be classified into two groups: Group 1, in which the viral population continued to replicate and Group 2, in which the viral load decreased significantly (P = 0.01727). Positioning of the mutations on the predicted IRES secondary structure showed that the distribution of the mutations and their apparition frequency were different between the two groups. At the early stage of treatment, IFN alpha-2a was efficient in reducing the viral replication in a significant number of patients; mechanisms of response might affect the virus directly. However, pre-treatment genomic variations observed in the 5'NCR of HCV were not a parameter of a later response to antiviral therapy in chronic hepatitis C patients. (244)
Collapse
Affiliation(s)
- M A Thélu
- Département d'Hépato-Gastroentérologie, Hôpital Albert Michallon, Grenoble, France
| | | | | | | | | | | |
Collapse
|
43
|
Tellinghuisen TL, Evans MJ, von Hahn T, You S, Rice CM. Studying hepatitis C virus: making the best of a bad virus. J Virol 2007; 81:8853-67. [PMID: 17522203 PMCID: PMC1951464 DOI: 10.1128/jvi.00753-07] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
|
44
|
McMullan LK, Grakoui A, Evans MJ, Mihalik K, Puig M, Branch AD, Feinstone SM, Rice CM. Evidence for a functional RNA element in the hepatitis C virus core gene. Proc Natl Acad Sci U S A 2007; 104:2879-84. [PMID: 17299041 PMCID: PMC1815275 DOI: 10.1073/pnas.0611267104] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In the core protein-coding region of hepatitis C virus (HCV), evidence exists for both phylogenetically conserved RNA structures and a +1 alternative reading frame (ARF). To investigate its role in HCV infection, we introduced four stop codons into the ARF of a genotype 1a H77 molecular clone. The changes did not alter the core protein sequence, but were predicted to disrupt RNA secondary structures. An attenuated infection was established after inoculation of the mutant HCV RNA into an HCV naïve chimpanzee. The acute infection was atypical with low peak viremia, minimal alanine aminotransferase elevation, and early virus control by a diverse adaptive immune response. Sequencing circulating virus revealed progressive reversions at the third and then fourth stop codon. In cell culture, RNA replication of a genome with four stop codons was severely impaired. In contrast, the revertant genome exhibited only a 5-fold reduction in replication. Genomes harboring only the first two stop codons replicated to WT levels. Similarly, reversions at stop codons 3 and 4, which improved replication, were selected with recombinant, infectious HCV in cell culture. We conclude that ARF-encoded proteins initiating at the polyprotein AUG are not essential for HCV replication in cell culture or in vivo. Rather, our results provide evidence for a functionally important RNA element in the ARF region.
Collapse
Affiliation(s)
- Laura K. McMullan
- *Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10021
| | - Arash Grakoui
- *Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10021
| | - Matthew J. Evans
- *Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10021
| | - Kathleen Mihalik
- Laboratory of Hepatitis Viruses, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892; and
| | - Montserrat Puig
- Laboratory of Hepatitis Viruses, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892; and
| | - Andrea D. Branch
- Division of Liver Disease, Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029
| | - Stephen M. Feinstone
- Laboratory of Hepatitis Viruses, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892; and
| | - Charles M. Rice
- *Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10021
- To whom correspondence should be addressed. E-mail:
| |
Collapse
|
45
|
Appel N, Bartenschlager R. A novel function for a micro RNA: negative regulators can do positive for the hepatitis C virus. Hepatology 2006; 43:612-5. [PMID: 16496334 DOI: 10.1002/hep.21092] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Nicole Appel
- Department of Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | | |
Collapse
|
46
|
Shimoike T, Koyama C, Murakami K, Suzuki R, Matsuura Y, Miyamura T, Suzuki T. Down-regulation of the internal ribosome entry site (IRES)-mediated translation of the hepatitis C virus: Critical role of binding of the stem-loop IIId domain of IRES and the viral core protein. Virology 2006; 345:434-45. [PMID: 16297950 DOI: 10.1016/j.virol.2005.10.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2005] [Revised: 07/01/2005] [Accepted: 10/07/2005] [Indexed: 01/06/2023]
Abstract
In a previous study, we observed that hepatitis C virus (HCV) core protein specifically inhibits translation initiated by an HCV internal ribosome entry site (IRES). To investigate the mechanism by which down-regulation of HCV translation occurs, a series of mutations were introduced into the IRES element, as well as the core protein, and their effect on IRES activity examined in this study. We found that expression of the core protein inhibits HCV translation possibly by binding to a stem-loop IIId domain, particularly a GGG triplet within the hairpin loop structure of the domain, within the IRES. Basic-residue clusters located at the N-terminus of the core protein have an inhibitory effect on HCV translation, and at least one of three known clusters is required for inhibition. We propose a model in which competitive binding of the core protein for the IRES and 40S ribosomal subunit regulates HCV translation.
Collapse
Affiliation(s)
- Takashi Shimoike
- Department of Virology II, National Institute of Infectious Diseases, Musashi-murayama, Tokyo 208-0011, Japan. ,jp
| | | | | | | | | | | | | |
Collapse
|
47
|
Meyer IM, Miklós I. Statistical evidence for conserved, local secondary structure in the coding regions of eukaryotic mRNAs and pre-mRNAs. Nucleic Acids Res 2005; 33:6338-48. [PMID: 16275783 PMCID: PMC1278941 DOI: 10.1093/nar/gki923] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Owing to the degeneracy of the genetic code, protein-coding regions of mRNA sequences can harbour more than only amino acid information. We search the mRNA sequences of 11 human protein-coding genes for evolutionarily conserved secondary structure elements using RNA-Decoder, a comparative secondary structure prediction program that is capable of explicitly taking the known protein-coding context of the mRNA sequences into account. We detect well-defined, conserved RNA secondary structure elements in the coding regions of the mRNA sequences and show that base-paired codons strongly correlate with sparse codons. We also investigate the role of repetitive elements in the formation of secondary structure and explain the use of alternate start codons in the caveolin-1 gene by a conserved secondary structure element overlapping the nominal start codon. We discuss the functional roles of our novel findings in regulating the gene expression on mRNA level. We also investigate the role of secondary structure on the correct splicing of the human CFTR gene. We study the wild-type version of the pre-mRNA as well as 29 variants with synonymous mutations in exon 12. By comparing our predicted secondary structures to the experimentally determined splicing efficiencies, we find with weak statistical significance that pre-mRNAs with high-splicing efficiencies have different predicted secondary structures than pre-mRNAs with low-splicing efficiencies.
Collapse
Affiliation(s)
- Irmtraud M Meyer
- European Bioinformatics Institute, Wellcome Trust Genome Campus, Cambridge CB10 1SD, UK.
| | | |
Collapse
|
48
|
Beguiristain N, Robertson HD, Gómez J. RNase III cleavage demonstrates a long range RNA: RNA duplex element flanking the hepatitis C virus internal ribosome entry site. Nucleic Acids Res 2005; 33:5250-61. [PMID: 16170153 PMCID: PMC1216335 DOI: 10.1093/nar/gki822] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Here, we show that Escherichia coli Ribonuclease III cleaves specifically the RNA genome of hepatitis C virus (HCV) within the first 570 nt with similar efficiency within two sequences which are ∼400 bases apart in the linear HCV map. Demonstrations include determination of the specificity of the cleavage sites at positions C27 and U33 in the first (5′) motif and G439 in the second (3′) motif, complete competition inhibition of 5′ and 3′ HCV RNA cleavages by added double-stranded RNA in a 1:6 to 1:8 weight ratio, respectively, 50% reverse competition inhibition of the RNase III T7 R1.1 mRNA substrate cleavage by HCV RNA at 1:1 molar ratio, and determination of the 5′ phosphate and 3′ hydroxyl end groups of the newly generated termini after cleavage. By comparing the activity and specificity of the commercial RNase III enzyme, used in this study, with the natural E.coli RNase III enzyme, on the natural bacteriophage T7 R1.1 mRNA substrate, we demonstrated that the HCV cuts fall into the category of specific, secondary RNase III cleavages. This reaction identifies regions of unusual RNA structure, and we further showed that blocking or deletion of one of the two RNase III-sensitive sequence motifs impeded cleavage at the other, providing direct evidence that both sequence motifs, besides being far apart in the linear RNA sequence, occur in a single RNA structural motif, which encloses the HCV internal ribosome entry site in a large RNA loop.
Collapse
Affiliation(s)
- Nerea Beguiristain
- Laboratorio de Medicina Interna, Hospital Vall d'Hebron, Barcelona 08035, Spain
| | | | | |
Collapse
|
49
|
Jopling CL, Yi M, Lancaster AM, Lemon SM, Sarnow P. Modulation of hepatitis C virus RNA abundance by a liver-specific MicroRNA. Science 2005; 309:1577-81. [PMID: 16141076 DOI: 10.1126/science.1113329] [Citation(s) in RCA: 1982] [Impact Index Per Article: 99.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
MicroRNAs are small RNA molecules that regulate messenger RNA (mRNA) expression. MicroRNA 122 (miR-122) is specifically expressed and highly abundant in the human liver. We show that the sequestration of miR-122 in liver cells results in marked loss of autonomously replicating hepatitis C viral RNAs. A genetic interaction between miR-122 and the 5' noncoding region of the viral genome was revealed by mutational analyses of the predicted microRNA binding site and ectopic expression of miR-122 molecules containing compensatory mutations. Studies with replication-defective RNAs suggested that miR-122 did not detectably affect mRNA translation or RNA stability. Therefore, miR-122 is likely to facilitate replication of the viral RNA, suggesting that miR-122 may present a target for antiviral intervention.
Collapse
Affiliation(s)
- Catherine L Jopling
- Department of Microbiology and Immunology, Stanford University, Stanford, CA 94305, USA
| | | | | | | | | |
Collapse
|
50
|
Kalliampakou KI, Kalamvoki M, Mavromara P. Hepatitis C virus (HCV) NS5A protein downregulates HCV IRES-dependent translation. J Gen Virol 2005; 86:1015-1025. [PMID: 15784895 DOI: 10.1099/vir.0.80728-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Translation of the hepatitis C virus (HCV) polyprotein is mediated by an internal ribosome entry site (IRES) that is located mainly within the 5' non-translated region of the viral genome. In this study, the effect of the HCV non-structural 5A (NS5A) protein on the HCV IRES-dependent translation was investigated by using a transient transfection system. Three different cell lines (HepG2, WRL-68 and BHK-21) were co-transfected with a plasmid vector containing a bicistronic transcript carrying the chloramphenicol acetyltransferase (CAT) and the firefly luciferase genes separated by the HCV IRES sequences, and an expression vector producing the NS5A protein. Here, it was shown that the HCV NS5A protein inhibited HCV IRES-dependent translation in a dose-dependent manner. In contrast, NS5A had no detectable effect on cap-dependent translation of the upstream gene (CAT) nor on translation from another viral IRES. Further analysis using deleted forms of the NS5A protein revealed that a region of about 120 aa located just upstream of the nuclear localization signal of the protein is critical for this suppression. Overall, these results suggest that HCV NS5A protein negatively modulates the HCV IRES activity in a specific manner.
Collapse
Affiliation(s)
- Katerina I Kalliampakou
- Molecular Virology Laboratory, Hellenic Pasteur Institute, 127 Vas. Sofias Avenue, Athens 115 21, Greece
| | - Maria Kalamvoki
- Molecular Virology Laboratory, Hellenic Pasteur Institute, 127 Vas. Sofias Avenue, Athens 115 21, Greece
| | - Penelope Mavromara
- Molecular Virology Laboratory, Hellenic Pasteur Institute, 127 Vas. Sofias Avenue, Athens 115 21, Greece
| |
Collapse
|