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Karousis ED, Schubert K, Ban N. Coronavirus takeover of host cell translation and intracellular antiviral response: a molecular perspective. EMBO J 2024; 43:151-167. [PMID: 38200146 PMCID: PMC10897431 DOI: 10.1038/s44318-023-00019-8] [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: 06/01/2023] [Revised: 11/01/2023] [Accepted: 11/24/2023] [Indexed: 01/12/2024] Open
Abstract
Coronaviruses are a group of related RNA viruses that cause respiratory diseases in humans and animals. Understanding the mechanisms of translation regulation during coronaviral infections is critical for developing antiviral therapies and preventing viral spread. Translation of the viral single-stranded RNA genome in the host cell cytoplasm is an essential step in the life cycle of coronaviruses, which affects the cellular mRNA translation landscape in many ways. Here we discuss various viral strategies of translation control, including how members of the Betacoronavirus genus shut down host cell translation and suppress host innate immune functions, as well as the role of the viral non-structural protein 1 (Nsp1) in the process. We also outline the fate of viral RNA, considering stress response mechanisms triggered in infected cells, and describe how unique viral RNA features contribute to programmed ribosomal -1 frameshifting, RNA editing, and translation shutdown evasion.
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Affiliation(s)
- Evangelos D Karousis
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Katharina Schubert
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Nenad Ban
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland.
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2
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Roberts L, Wieden HJ. The prokaryotic activity of the IGR IRESs is mediated by ribosomal protein S1. Nucleic Acids Res 2022; 50:9355-9367. [PMID: 36039756 PMCID: PMC9458429 DOI: 10.1093/nar/gkac697] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Accepted: 08/03/2022] [Indexed: 12/24/2022] Open
Abstract
Internal ribosome entry sites (IRESs) are RNA elements capable of initiating translation on an internal portion of a messenger RNA. The intergenic region (IGR) IRES of the Dicistroviridae virus family folds into a triple pseudoknot tertiary structure, allowing it to recruit the ribosome and initiate translation in a structure dependent manner. This IRES has also been reported to drive translation in Escherichia coli and to date is the only described translation initiation signal that functions across domains of life. Here we show that unlike in the eukaryotic context the tertiary structure of the IGR IRES is not required for prokaryotic ribosome recruitment. In E. coli IGR IRES translation efficiency is dependent on ribosomal protein S1 in conjunction with an AG-rich Shine-Dalgarno-like element, supporting a model where the translational activity of the IGR IRESs is due to S1-mediated canonical prokaryotic translation.
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Affiliation(s)
- Luc Roberts
- Alberta RNA Research and Training Institute, Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, Canada
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3
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Wang Y, Wu C, Du Y, Li Z, Li M, Hou P, Shen Z, Chu S, Zheng J, Bai J. Expanding uncapped translation and emerging function of circular RNA in carcinomas and noncarcinomas. Mol Cancer 2022; 21:13. [PMID: 34996480 PMCID: PMC8740365 DOI: 10.1186/s12943-021-01484-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 12/16/2021] [Indexed: 02/07/2023] Open
Abstract
Circular RNAs (circRNAs) are classified as noncoding RNAs because they are devoid of a 5' end cap and a 3' end poly (A) tail necessary for cap-dependent translation. However, increasing numbers of translated circRNAs identified through high-throughput RNA sequencing overlapping with polysome profiling indicate that this rule is being broken. CircRNAs can be translated in cap-independent mechanism, including IRES (internal ribosome entry site)-initiated pattern, MIRES (m6A internal ribosome entry site) -initiated patterns, and rolling translation mechanism (RCA). CircRNA-encoded proteins harbour diverse functions similar to or different from host proteins. In addition, they are linked to the modulation of human disease including carcinomas and noncarcinomas. CircRNA-related translatomics and proteomics have attracted increasing attention. This review discusses the progress and exclusive characteristics of circRNA translation and highlights the latest mechanisms and regulation of circRNA translatomics. Furthermore, we summarize the extensive functions and mechanisms of circRNA-derived proteins in human diseases, which contribute to a better understanding of intricate noncanonical circRNA translatomics and proteomics and their therapeutic potential in human diseases.
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Affiliation(s)
- Yan Wang
- Cancer Institute, Xuzhou Medical University, 84 West Huaihai Road, Xuzhou, 221002, Jiangsu Province, China
- Center of Clinical Oncology, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
- Department of Pharmacy, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Chunjie Wu
- Cancer Institute, Xuzhou Medical University, 84 West Huaihai Road, Xuzhou, 221002, Jiangsu Province, China
- Department of Pharmacy, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Yu Du
- Cancer Institute, Xuzhou Medical University, 84 West Huaihai Road, Xuzhou, 221002, Jiangsu Province, China
- Department of Pharmacy, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Zhongwei Li
- Cancer Institute, Xuzhou Medical University, 84 West Huaihai Road, Xuzhou, 221002, Jiangsu Province, China
| | - Minle Li
- Cancer Institute, Xuzhou Medical University, 84 West Huaihai Road, Xuzhou, 221002, Jiangsu Province, China
| | - Pingfu Hou
- Cancer Institute, Xuzhou Medical University, 84 West Huaihai Road, Xuzhou, 221002, Jiangsu Province, China
| | - Zhigang Shen
- Cancer Institute, Xuzhou Medical University, 84 West Huaihai Road, Xuzhou, 221002, Jiangsu Province, China
| | - Sufang Chu
- Cancer Institute, Xuzhou Medical University, 84 West Huaihai Road, Xuzhou, 221002, Jiangsu Province, China
| | - Junnian Zheng
- Cancer Institute, Xuzhou Medical University, 84 West Huaihai Road, Xuzhou, 221002, Jiangsu Province, China.
- Center of Clinical Oncology, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China.
| | - Jin Bai
- Cancer Institute, Xuzhou Medical University, 84 West Huaihai Road, Xuzhou, 221002, Jiangsu Province, China.
- Center of Clinical Oncology, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China.
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4
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Wang X, Marchisio MA. Synthetic polycistronic sequences in eukaryotes. Synth Syst Biotechnol 2021; 6:254-261. [PMID: 34584993 PMCID: PMC8449083 DOI: 10.1016/j.synbio.2021.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/31/2021] [Accepted: 09/02/2021] [Indexed: 12/18/2022] Open
Abstract
The need for co-ordinate, high-level, and stable expression of multiple genes is essential for the engineering of biosynthetic circuits and metabolic pathways. This work outlines the functionality and design of IRES- and 2 A-peptide-based constructs by comparing different strategies for co-expression in polycistronic vectors. In particular, 2 A sequences are small peptides, mostly derived from viral polyproteins, that mediate a ribosome-skipping event such that several, different, separate proteins can be generated from a single open reading frame. When applied to metabolic engineering and synthetic gene circuits, 2 A peptides permit to achieve co-regulated and reliable expression of various genes in eukaryotic cells.
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Affiliation(s)
- Xuekun Wang
- School of Pharmaceutical Science and Technology, Tianjin University, 92 Weijin Road, 300072, Tianjin, China
| | - Mario Andrea Marchisio
- School of Pharmaceutical Science and Technology, Tianjin University, 92 Weijin Road, 300072, Tianjin, China
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Liu F, Wang N, Wang Q, Shan H. Motif mutations in pseudoknot stem I upstream of start codon in Senecavirus A genome: Impacts on activity of viral IRES and on rescue of recombinant virus. Vet Microbiol 2021; 262:109223. [PMID: 34507016 DOI: 10.1016/j.vetmic.2021.109223] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Accepted: 08/30/2021] [Indexed: 12/12/2022]
Abstract
Senecavirus A (SVA), formerly known as Seneca Valley virus, is classified into the genus Senecavirus in the family Picornaviridae. Mature virion harbors an approximately 7 300-nt-long, positive-sense, and single-stranded RNA genome, which contains 5' and 3' untranslated regions (UTRs). Internal ribosome entry site (IRES) is identified in the SVA 5' UTR, and includes a RNA pseudoknot upstream of the start codon. This pseudoknot contains two stem structures, pseudoknot stem I and II (PKS-I and -II). The PKS-I is composed of two base-paired motifs (PKS-Ia and -Ib), between which there is an unpaired spacing (UpS). We reported previously that motif mutation in the PKS-II did not abolish the IRES activity, but interfered with SVA recovery from cDNA clone. In this study, we constructed five SVA minigenomes with point mutations in the PKS-I motif. Dual-luciferase reporter assay showed that motif mutations in PKS-I did not significantly interfere with the IRES activity to initiate protein expression. Correspondingly, we constructed five SVA cDNA clones with point mutations in the PKS-I motif. These genetically modified cDNA clones were separately transfected into BSR-T7/5 cells in attempting to rescue competent SVAs. However, only two viruses, namely PKS-Ia- and UpS-mutated recombinants, could be recovered from their individual cDNA clones. It can be concluded that the PKS-Ib is indispensable for viral growth.
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Affiliation(s)
- Fuxiao Liu
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China.
| | - Ning Wang
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Qi Wang
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Hu Shan
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China.
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Dissection of a rice OsMac1 mRNA 5' UTR to uncover regulatory elements that are responsible for its efficient translation. PLoS One 2021; 16:e0253488. [PMID: 34242244 PMCID: PMC8270207 DOI: 10.1371/journal.pone.0253488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 06/07/2021] [Indexed: 11/19/2022] Open
Abstract
The untranslated regions (UTRs) of mRNAs are involved in many posttranscriptional regulatory pathways. The rice OsMac1 mRNA has three splicing variants of the 5' UTR (UTRa, UTRb, and UTRc), which include a CU-rich region and three upstream open reading frames (uORFs). UTRc contains an additional 38-nt sequence, termed sp38, which acts as a strong translational enhancer of the downstream ORF; reporter analysis revealed translational efficiencies >15-fold higher with UTRc than with the other splice variants. Mutation analysis of UTRc demonstrated that an optimal sequence length of sp38, rather than its nucleotide sequence is essential for UTRc to promote efficient translation. In addition, the 5' 100 nucleotides of CU-rich region contribute to UTRc translational enhancement. Strikingly, three uORFs did not reveal their inhibitory potential within the full-length leader, whereas deletion of the 5' leader fragment preceding the leader region with uORFs nearly abolished translation. Computational prediction of UTRc structural motifs revealed stem-loop structures, termed SL1-SL4, and two regions, A and B, involved in putative intramolecular interactions. Our data suggest that SL4 binding to Region-A and base pairing between Region-B and the UTRc 3'end are critically required for translational enhancement. Since UTRc is not capable of internal initiation, we presume that the three-dimensional leader structures can allow translation of the leader downstream ORF, likely allowing the bypass of uORFs.
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Sauter D, Kirchhoff F. Evolutionary conflicts and adverse effects of antiviral factors. eLife 2021; 10:e65243. [PMID: 33450175 PMCID: PMC7811402 DOI: 10.7554/elife.65243] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/06/2021] [Indexed: 12/13/2022] Open
Abstract
Human cells are equipped with a plethora of antiviral proteins protecting them against invading viral pathogens. In contrast to apoptotic or pyroptotic cell death, which serves as ultima ratio to combat viral infections, these cell-intrinsic restriction factors may prevent or at least slow down viral spread while allowing the host cell to survive. Nevertheless, their antiviral activity may also have detrimental effects on the host. While the molecular mechanisms underlying the antiviral activity of restriction factors are frequently well investigated, potential undesired effects of their antiviral functions on the host cell are hardly explored. With a focus on antiretroviral proteins, we summarize in this review how individual restriction factors may exert adverse effects as trade-off for efficient defense against attacking pathogens.
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Affiliation(s)
- Daniel Sauter
- Institute of Molecular Virology, Ulm University Medical CenterUlmGermany
- Institute of Medical Virology and Epidemiology of Viral Diseases, University Hospital TübingenTübingenGermany
| | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical CenterUlmGermany
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Erasmus JH, Archer J, Fuerte-Stone J, Khandhar AP, Voigt E, Granger B, Bombardi RG, Govero J, Tan Q, Durnell LA, Coler RN, Diamond MS, Crowe JE, Reed SG, Thackray LB, Carnahan RH, Van Hoeven N. Intramuscular Delivery of Replicon RNA Encoding ZIKV-117 Human Monoclonal Antibody Protects against Zika Virus Infection. Mol Ther Methods Clin Dev 2020; 18:402-414. [PMID: 32695842 PMCID: PMC7363633 DOI: 10.1016/j.omtm.2020.06.011] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 05/15/2020] [Indexed: 12/31/2022]
Abstract
Monoclonal antibody (mAb) therapeutics are an effective modality for the treatment of infectious, autoimmune, and cancer-related diseases. However, the discovery, development, and manufacturing processes are complex, resource-consuming activities that preclude the rapid deployment of mAbs in outbreaks of emerging infectious diseases. Given recent advances in nucleic acid delivery technology, it is now possible to deliver exogenous mRNA encoding mAbs for in situ expression following intravenous (i.v.) infusion of lipid nanoparticle-encapsulated mRNA. However, the requirement for i.v. administration limits the application to settings where infusion is an option, increasing the cost of treatment. As an alternative strategy, and to enable intramuscular (IM) administration of mRNA-encoded mAbs, we describe a nanostructured lipid carrier for delivery of an alphavirus replicon encoding a previously described highly neutralizing human mAb, ZIKV-117. Using a lethal Zika virus challenge model in mice, our studies show robust protection following alphavirus-driven expression of ZIKV-117 mRNA when given by IM administration as pre-exposure prophylaxis or post-exposure therapy.
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Affiliation(s)
- Jesse H. Erasmus
- Pre-Clinical Vaccine Development, Infectious Disease Research Institute, Seattle, WA, USA
- HDT Biocorp, Seattle, WA, USA
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - Jacob Archer
- Pre-Clinical Vaccine Development, Infectious Disease Research Institute, Seattle, WA, USA
- HDT Biocorp, Seattle, WA, USA
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - Jasmine Fuerte-Stone
- Pre-Clinical Vaccine Development, Infectious Disease Research Institute, Seattle, WA, USA
| | - Amit P. Khandhar
- Pre-Clinical Vaccine Development, Infectious Disease Research Institute, Seattle, WA, USA
- HDT Biocorp, Seattle, WA, USA
| | - Emily Voigt
- Pre-Clinical Vaccine Development, Infectious Disease Research Institute, Seattle, WA, USA
| | - Brian Granger
- Pre-Clinical Vaccine Development, Infectious Disease Research Institute, Seattle, WA, USA
| | - Robin G. Bombardi
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 27232, USA
| | - Jennifer Govero
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Qing Tan
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Lorellin A. Durnell
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Rhea N. Coler
- Pre-Clinical Vaccine Development, Infectious Disease Research Institute, Seattle, WA, USA
| | - Michael S. Diamond
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - James E. Crowe
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 27232, USA
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 27232, USA
- Department of Pathology Microbiology & Immunology, Vanderbilt University Medical Center, Nashville, TN 27232, USA
| | - Steven G. Reed
- Pre-Clinical Vaccine Development, Infectious Disease Research Institute, Seattle, WA, USA
- HDT Biocorp, Seattle, WA, USA
| | - Larissa B. Thackray
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Robert H. Carnahan
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 27232, USA
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 27232, USA
| | - Neal Van Hoeven
- Pre-Clinical Vaccine Development, Infectious Disease Research Institute, Seattle, WA, USA
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Gunaseelan S, Wong KZ, Min N, Sun J, Ismail NKBM, Tan YJ, Lee RCH, Chu JJH. Prunin suppresses viral IRES activity and is a potential candidate for treating enterovirus A71 infection. Sci Transl Med 2020; 11:11/516/eaar5759. [PMID: 31666401 DOI: 10.1126/scitranslmed.aar5759] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 11/12/2018] [Accepted: 10/09/2019] [Indexed: 12/24/2022]
Abstract
Human enterovirus A71 (HEVA71) causes hand, foot, and mouth disease (HFMD) in young children and is considered a major neurotropic pathogen but lacks effective antivirals. To identify potential therapeutic agents against HFMD, we screened a 502-compound flavonoid library for compounds targeting the HEVA71 internal ribosome entry site (IRES) that facilitates translation of the HEVA71 genome and is vital for the production of HEVA71 viral particles. We validated hits using cell viability and viral plaque assays and found that prunin was the most potent inhibitor of HEVA71. Downstream assays affirmed that prunin disrupted viral protein and RNA synthesis and acted as a narrow-spectrum antiviral against enteroviruses A and B, but not enterovirus C, rhinovirus A, herpes simplex 1, or chikungunya virus. Continuous HEVA71 passaging with prunin yielded HEVA71-resistant mutants with five mutations that mapped to the viral IRES. Knockdown studies showed that the mutations allowed HEVA71 to overcome treatment-induced suppression by differentially regulating recruitment of the IRES trans-acting factors Sam68 and hnRNPK without affecting the hnRNPA1-IRES interaction required for IRES translation. Furthermore, prunin effectively reduced HEVA71-associated clinical symptoms and mortality in HEVA71-infected BALB/c mice and suppressed hepatitis C virus at higher concentrations, suggesting a similar mechanism of prunin-mediated IRES inhibition for both viruses. These studies establish prunin as a candidate for further development as a HEVA71 therapeutic agent.
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Affiliation(s)
- Saravanan Gunaseelan
- Department of Microbiology and Immunology, National University of Singapore, Singapore 117597, Singapore
| | - Kai Zhi Wong
- Department of Microbiology and Immunology, National University of Singapore, Singapore 117597, Singapore
| | - Nyo Min
- Department of Microbiology and Immunology, National University of Singapore, Singapore 117597, Singapore
| | - Jialei Sun
- Department of Microbiology and Immunology, National University of Singapore, Singapore 117597, Singapore
| | | | - Yee Joo Tan
- Department of Microbiology and Immunology, National University of Singapore, Singapore 117597, Singapore
| | - Regina Ching Hua Lee
- Department of Microbiology and Immunology, National University of Singapore, Singapore 117597, Singapore
| | - Justin Jang Hann Chu
- Department of Microbiology and Immunology, National University of Singapore, Singapore 117597, Singapore. .,Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore 138673, Singapore
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Quaranta P, Lottini G, Chesi G, Contrafatto F, Russotto R, Macera L, Lai M, Spezia PG, Brai A, Botta M, Freer G, Pistello M. DDX3 inhibitors show antiviral activity against positive-sense single-stranded RNA viruses but not against negative-sense single-stranded RNA viruses: The coxsackie B model. Antiviral Res 2020; 178:104750. [DOI: 10.1016/j.antiviral.2020.104750] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 02/08/2020] [Accepted: 02/18/2020] [Indexed: 10/24/2022]
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Mechanisms Mediating Nuclear Trafficking Involved in Viral Propagation by DNA Viruses. Viruses 2019; 11:v11111035. [PMID: 31703327 PMCID: PMC6893576 DOI: 10.3390/v11111035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Revised: 10/30/2019] [Accepted: 10/31/2019] [Indexed: 02/06/2023] Open
Abstract
Typical viral propagation involves sequential viral entry, uncoating, replication, gene transcription and protein synthesis, and virion assembly and release. Some viral proteins must be transported into host nucleus to facilitate viral propagation, which is essential for the production of mature virions. During the transport process, nuclear localization signals (NLSs) play an important role in guiding target proteins into nucleus through the nuclear pore. To date, some classical nuclear localization signals (cNLSs) and non-classical NLSs (ncNLSs) have been identified in a number of viral proteins. These proteins are involved in viral replication, expression regulation of viral genes and virion assembly. Moreover, other proteins are transported into nucleus with unknown mechanisms. This review highlights our current knowledge about the nuclear trafficking of cellular proteins associated with viral propagation.
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Selinger M, Tykalová H, Štěrba J, Věchtová P, Vavrušková Z, Lieskovská J, Kohl A, Schnettler E, Grubhoffer L. Tick-borne encephalitis virus inhibits rRNA synthesis and host protein production in human cells of neural origin. PLoS Negl Trop Dis 2019; 13:e0007745. [PMID: 31560682 PMCID: PMC6785130 DOI: 10.1371/journal.pntd.0007745] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 10/09/2019] [Accepted: 09/03/2019] [Indexed: 12/11/2022] Open
Abstract
Tick-borne encephalitis virus (TBEV), a member of the genus Flavivirus (Flaviviridae), is a causative agent of a severe neuroinfection. Recently, several flaviviruses have been shown to interact with host protein synthesis. In order to determine whether TBEV interacts with this host process in its natural target cells, we analysed de novo protein synthesis in a human cell line derived from cerebellar medulloblastoma (DAOY HTB-186). We observed a significant decrease in the rate of host protein synthesis, including the housekeeping genes HPRT1 and GAPDH and the known interferon-stimulated gene viperin. In addition, TBEV infection resulted in a specific decrease of RNA polymerase I (POLR1) transcripts, 18S and 28S rRNAs and their precursor, 45-47S pre-rRNA, but had no effect on the POLR3 transcribed 5S rRNA levels. To our knowledge, this is the first report of flavivirus-induced decrease of specifically POLR1 rRNA transcripts accompanied by host translational shut-off. Tick-borne encephalitis virus (TBEV) is a causative agent of a severe human neuroinfection that threatens Europe and Asia. Little is known about the interaction of this neurotropic virus with neural cells, even though this may be important to better understand why or how TBEV can cause high pathogenicity in humans, especially following neural cell infection. Here, we showed that TBEV induced host translational shut-off in cells of neural origin. In addition, TBEV interfered also with the expression of host ribosomal RNAs. Interestingly, the transcriptional shut-off was documented for rRNA species transcribed by RNA polymerase I (18S rRNA, 28S rRNA and their precursor 45-47S pre-rRNA), but not for RNA polymerase III rRNA transcripts (5S rRNA). Artificial inhibition of host translation using cycloheximide resulted in the decrease of all rRNA species. Based on these data, TBEV seems to specifically target transcription of RNA polymerase I. These new findings further increase our understanding of TBEV interactions with a key target cell type.
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Affiliation(s)
- Martin Selinger
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
| | - Hana Tykalová
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
| | - Ján Štěrba
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
| | - Pavlína Věchtová
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
| | - Zuzana Vavrušková
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
| | - Jaroslava Lieskovská
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
| | - Esther Schnettler
- Bernhard-Nocht-Institute for Tropical Medicine, Bernhard-Nocht-Str. 74, Hamburg, Germany
- German Centre for Infection Research (DZIF), partner site Hamburg-Luebeck-Borstel-Riems, Hamburg, Germany
- * E-mail: (ES); (LG)
| | - Libor Grubhoffer
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
- * E-mail: (ES); (LG)
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