1
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Mahé M, Rios-Fuller T, Katsara O, Schneider RJ. Non-canonical mRNA translation initiation in cell stress and cancer. NAR Cancer 2024; 6:zcae026. [PMID: 38828390 PMCID: PMC11140632 DOI: 10.1093/narcan/zcae026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 05/08/2024] [Accepted: 05/29/2024] [Indexed: 06/05/2024] Open
Abstract
The now well described canonical mRNA translation initiation mechanism of m7G 'cap' recognition by cap-binding protein eIF4E and assembly of the canonical pre-initiation complex consisting of scaffolding protein eIF4G and RNA helicase eIF4A has historically been thought to describe all cellular mRNA translation. However, the past decade has seen the discovery of alternative mechanisms to canonical eIF4E mediated mRNA translation initiation. Studies have shown that non-canonical alternate mechanisms of cellular mRNA translation initiation, whether cap-dependent or independent, serve to provide selective translation of mRNAs under cell physiological and pathological stress conditions. These conditions typically involve the global downregulation of canonical eIF4E1/cap-mediated mRNA translation, and selective translational reprogramming of the cell proteome, as occurs in tumor development and malignant progression. Cancer cells must be able to maintain physiological plasticity to acquire a migratory phenotype, invade tissues, metastasize, survive and adapt to severe microenvironmental stress conditions that involve inhibition of canonical mRNA translation initiation. In this review we describe the emerging, important role of non-canonical, alternate mechanisms of mRNA translation initiation in cancer, particularly in adaptation to stresses and the phenotypic cell fate changes involved in malignant progression and metastasis. These alternate translation initiation mechanisms provide new targets for oncology therapeutics development.
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Affiliation(s)
- Mélanie Mahé
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY 10016, USA
| | - Tiffany Rios-Fuller
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY 10016, USA
| | - Olga Katsara
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY 10016, USA
| | - Robert J Schneider
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY 10016, USA
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2
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Li Y, Zhang L, Wang L, Li J, Zhao Y, Liu F, Wang Q. Structure and function of type IV IRES in picornaviruses: a systematic review. Front Microbiol 2024; 15:1415698. [PMID: 38855772 PMCID: PMC11157119 DOI: 10.3389/fmicb.2024.1415698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Accepted: 05/13/2024] [Indexed: 06/11/2024] Open
Abstract
The Picornaviridae is a family of icosahedral viruses with single-stranded, highly diverse positive-sense RNA genomes. Virions consist of a capsid, without envelope, surrounding a core of RNA genome. A typical genome of picornavirus harbors a well-conserved and highly structured RNA element known as the internal ribosome entry site (IRES), functionally essential for viral replication and protein translation. Based on differences in their structures and mechanisms of action, picornaviral IRESs have been categorized into five types: type I, II, III, IV, and V. Compared with the type IV IRES, the others not only are structurally complicated, but also involve multiple initiation factors for triggering protein translation. The type IV IRES, often referred to as hepatitis C virus (HCV)-like IRES due to its structural resemblance to the HCV IRES, exhibits a simpler and more compact structure than those of the other four. The increasing identification of picornaviruses with the type IV IRES suggests that this IRES type seems to reveal strong retention and adaptation in terms of viral evolution. Here, we systematically reviewed structural features and biological functions of the type IV IRES in picornaviruses. A comprehensive understanding of the roles of type IV IRESs will contribute to elucidating the replication mechanism and pathogenesis of picornaviruses.
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Affiliation(s)
- Yan Li
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, China
- Qingdao Center for Animal Disease Control and Prevention, Qingdao, China
| | - Lei Zhang
- Shandong New Hope Liuhe Group Co., Ltd., Qingdao, China
| | - Ling Wang
- University Hospital, Qingdao Agricultural University, Qingdao, China
| | - Jing Li
- Market Supervision Administration of Huangdao District, Qingdao, China
| | - Yanwei Zhao
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, China
| | - Fuxiao Liu
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, China
| | - Qianqian Wang
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, China
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3
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Eisenhut P, Marx N, Borsi G, Papež M, Ruggeri C, Baumann M, Borth N. Manipulating gene expression levels in mammalian cell factories: An outline of synthetic molecular toolboxes to achieve multiplexed control. N Biotechnol 2024; 79:1-19. [PMID: 38040288 DOI: 10.1016/j.nbt.2023.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/06/2023] [Accepted: 11/26/2023] [Indexed: 12/03/2023]
Abstract
Mammalian cells have developed dedicated molecular mechanisms to tightly control expression levels of their genes where the specific transcriptomic signature across all genes eventually determines the cell's phenotype. Modulating cellular phenotypes is of major interest to study their role in disease or to reprogram cells for the manufacturing of recombinant products, such as biopharmaceuticals. Cells of mammalian origin, for example Chinese hamster ovary (CHO) and Human embryonic kidney 293 (HEK293) cells, are most commonly employed to produce therapeutic proteins. Early genetic engineering approaches to alter their phenotype have often been attempted by "uncontrolled" overexpression or knock-down/-out of specific genetic factors. Many studies in the past years, however, highlight that rationally regulating and fine-tuning the strength of overexpression or knock-down to an optimum level, can adjust phenotypic traits with much more precision than such "uncontrolled" approaches. To this end, synthetic biology tools have been generated that enable (fine-)tunable and/or inducible control of gene expression. In this review, we discuss various molecular tools used in mammalian cell lines and group them by their mode of action: transcriptional, post-transcriptional, translational and post-translational regulation. We discuss the advantages and disadvantages of using these tools for each cell regulatory layer and with respect to cell line engineering approaches. This review highlights the plethora of synthetic toolboxes that could be employed, alone or in combination, to optimize cellular systems and eventually gain enhanced control over the cellular phenotype to equip mammalian cell factories with the tools required for efficient production of emerging, more difficult-to-express biologics formats.
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Affiliation(s)
- Peter Eisenhut
- Austrian Centre of Industrial Biotechnology (acib GmbH), Muthgasse 11, 1190 Vienna, Austria
| | - Nicolas Marx
- BOKU University of Natural Resources and Life Sciences, Institute of Animal Cell Technology and Systems Biology, Muthgasse 18, 1190 Vienna, Austria.
| | - Giulia Borsi
- BOKU University of Natural Resources and Life Sciences, Institute of Animal Cell Technology and Systems Biology, Muthgasse 18, 1190 Vienna, Austria
| | - Maja Papež
- Austrian Centre of Industrial Biotechnology (acib GmbH), Muthgasse 11, 1190 Vienna, Austria; BOKU University of Natural Resources and Life Sciences, Institute of Animal Cell Technology and Systems Biology, Muthgasse 18, 1190 Vienna, Austria
| | - Caterina Ruggeri
- BOKU University of Natural Resources and Life Sciences, Institute of Animal Cell Technology and Systems Biology, Muthgasse 18, 1190 Vienna, Austria
| | - Martina Baumann
- Austrian Centre of Industrial Biotechnology (acib GmbH), Muthgasse 11, 1190 Vienna, Austria
| | - Nicole Borth
- Austrian Centre of Industrial Biotechnology (acib GmbH), Muthgasse 11, 1190 Vienna, Austria; BOKU University of Natural Resources and Life Sciences, Institute of Animal Cell Technology and Systems Biology, Muthgasse 18, 1190 Vienna, Austria.
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4
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Khan D, Fox PL. Host-like RNA Elements Regulate Virus Translation. Viruses 2024; 16:468. [PMID: 38543832 PMCID: PMC10976276 DOI: 10.3390/v16030468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 03/14/2024] [Accepted: 03/17/2024] [Indexed: 04/01/2024] Open
Abstract
Viruses are obligate, intracellular parasites that co-opt host cell machineries for propagation. Critical among these machineries are those that translate RNA into protein and their mechanisms of control. Most regulatory mechanisms effectuate their activity by targeting sequence or structural features at the RNA termini, i.e., at the 5' or 3' ends, including the untranslated regions (UTRs). Translation of most eukaryotic mRNAs is initiated by 5' cap-dependent scanning. In contrast, many viruses initiate translation at internal RNA regions at internal ribosome entry sites (IRESs). Eukaryotic mRNAs often contain upstream open reading frames (uORFs) that permit condition-dependent control of downstream major ORFs. To offset genome compression and increase coding capacity, some viruses take advantage of out-of-frame overlapping uORFs (oORFs). Lacking the essential machinery of protein synthesis, for example, ribosomes and other translation factors, all viruses utilize the host apparatus to generate virus protein. In addition, some viruses exhibit RNA elements that bind host regulatory factors that are not essential components of the translation machinery. SARS-CoV-2 is a paradigm example of a virus taking advantage of multiple features of eukaryotic host translation control: the virus mimics the established human GAIT regulatory element and co-opts four host aminoacyl tRNA synthetases to form a stimulatory binding complex. Utilizing discontinuous transcription, the elements are present and identical in all SARS-CoV-2 subgenomic RNAs (and the genomic RNA). Thus, the virus exhibits a post-transcriptional regulon that improves upon analogous eukaryotic regulons, in which a family of functionally related mRNA targets contain elements that are structurally similar but lacking sequence identity. This "thrifty" virus strategy can be exploited against the virus since targeting the element can suppress the expression of all subgenomic RNAs as well as the genomic RNA. Other 3' end viral elements include 3'-cap-independent translation elements (3'-CITEs) and 3'-tRNA-like structures. Elucidation of virus translation control elements, their binding proteins, and their mechanisms can lead to novel therapeutic approaches to reduce virus replication and pathogenicity.
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Affiliation(s)
- Debjit Khan
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Paul L. Fox
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
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5
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Tamura T, Yamamoto H, Ogino S, Morioka Y, Tsujino S, Suzuki R, Hiono T, Suzuki S, Isoda N, Sakoda Y, Fukuhara T. A rapid and versatile reverse genetics approach for generating recombinant positive-strand RNA viruses that use IRES-mediated translation. J Virol 2024; 98:e0163823. [PMID: 38353536 PMCID: PMC10949505 DOI: 10.1128/jvi.01638-23] [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: 10/19/2023] [Accepted: 01/24/2024] [Indexed: 03/20/2024] Open
Abstract
Reverse genetics systems have played a central role in developing recombinant viruses for a wide spectrum of virus research. The circular polymerase extension reaction (CPER) method has been applied to studying positive-strand RNA viruses, allowing researchers to bypass molecular cloning of viral cDNA clones and thus leading to the rapid generation of recombinant viruses. However, thus far, the CPER protocol has only been established using cap-dependent RNA viruses. Here, we demonstrate that a modified version of the CPER method can be successfully applied to positive-strand RNA viruses that use cap-independent, internal ribosomal entry site (IRES)-mediated translation. As a proof-of-concept, we employed mammalian viruses with different types (classes I, II, and III) of IRES to optimize the CPER method. Using the hepatitis C virus (HCV, class III), we found that inclusion in the CPER assembly of an RNA polymerase I promoter and terminator, instead of those from polymerase II, allowed greater viral production. This approach was also successful in generating recombinant bovine viral diarrhea virus (class III) following transfection of MDBK/293T co-cultures to overcome low transfection efficiency. In addition, we successfully generated the recombinant viruses from clinical specimens. Our modified CPER could be used for producing hepatitis A virus (HAV, type I) as well as de novo generation of encephalomyocarditis virus (type II). Finally, we generated recombinant HCV and HAV reporter viruses that exhibited replication comparable to that of the wild-type parental viruses. The recombinant HAV reporter virus helped evaluate antivirals. Taking the findings together, this study offers methodological advances in virology. IMPORTANCE The lack of versatility of reverse genetics systems remains a bottleneck in viral research. Especially when (re-)emerging viruses reach pandemic levels, rapid characterization and establishment of effective countermeasures using recombinant viruses are beneficial in disease control. Indeed, numerous studies have attempted to establish and improve the methods. The circular polymerase extension reaction (CPER) method has overcome major obstacles in generating recombinant viruses. However, this method has not yet been examined for positive-strand RNA viruses that use cap-independent, internal ribosome entry site-mediated translation. Here, we engineered a suitable gene cassette to expand the CPER method for all positive-strand RNA viruses. Furthermore, we overcame the difficulty of generating recombinant viruses because of low transfection efficiency. Using this modified method, we also successfully generated reporter viruses and recombinant viruses from a field sample without virus isolation. Taking these findings together, our adapted methodology is an innovative technology that could help advance virologic research.
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Affiliation(s)
- Tomokazu Tamura
- Department of Microbiology and Immunology, Faculty of Medicine, Hokkaido University, Sapporo, Japan
- Institute for Vaccine Research and Development (IVReD), Hokkaido University, Sapporo, Japan
- One Health Research Center, Hokkaido University, Sapporo, Japan
| | - Hirotaka Yamamoto
- Department of Microbiology and Immunology, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Saho Ogino
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Yuhei Morioka
- Department of Microbiology and Immunology, Faculty of Medicine, Hokkaido University, Sapporo, Japan
- Laboratory of Virus Control, Research Institute for Microbial Diseases, Osaka University, Suita, Japan
| | - Shuhei Tsujino
- Department of Microbiology and Immunology, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Rigel Suzuki
- Department of Microbiology and Immunology, Faculty of Medicine, Hokkaido University, Sapporo, Japan
- Institute for Vaccine Research and Development (IVReD), Hokkaido University, Sapporo, Japan
| | - Takahiro Hiono
- Institute for Vaccine Research and Development (IVReD), Hokkaido University, Sapporo, Japan
- One Health Research Center, Hokkaido University, Sapporo, Japan
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
- International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Saori Suzuki
- Department of Microbiology and Immunology, Faculty of Medicine, Hokkaido University, Sapporo, Japan
- Institute for Vaccine Research and Development (IVReD), Hokkaido University, Sapporo, Japan
| | - Norikazu Isoda
- Institute for Vaccine Research and Development (IVReD), Hokkaido University, Sapporo, Japan
- One Health Research Center, Hokkaido University, Sapporo, Japan
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
- International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Yoshihiro Sakoda
- Institute for Vaccine Research and Development (IVReD), Hokkaido University, Sapporo, Japan
- One Health Research Center, Hokkaido University, Sapporo, Japan
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
- International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Takasuke Fukuhara
- Department of Microbiology and Immunology, Faculty of Medicine, Hokkaido University, Sapporo, Japan
- Institute for Vaccine Research and Development (IVReD), Hokkaido University, Sapporo, Japan
- One Health Research Center, Hokkaido University, Sapporo, Japan
- Laboratory of Virus Control, Research Institute for Microbial Diseases, Osaka University, Suita, Japan
- AMED-CREST, Japan Agency for Medical Research and Development (AMED), Tokyo, Japan
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6
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Fernández-García L, Ahumada-Marchant C, Lobos-Ávila P, Brauer B, Bustos FJ, Arriagada G. The Mytilus chilensis Steamer-like Element-1 Retrotransposon Antisense mRNA Harbors an Internal Ribosome Entry Site That Is Modulated by hnRNPK. Viruses 2024; 16:403. [PMID: 38543768 PMCID: PMC10974842 DOI: 10.3390/v16030403] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 02/29/2024] [Accepted: 03/03/2024] [Indexed: 05/23/2024] Open
Abstract
LTR-retrotransposons are transposable elements characterized by the presence of long terminal repeats (LTRs) directly flanking an internal coding region. They share genome organization and replication strategies with retroviruses. Steamer-like Element-1 (MchSLE-1) is an LTR-retrotransposon identified in the genome of the Chilean blue mussel Mytilus chilensis. MchSLE-1 is transcribed; however, whether its RNA is also translated and the mechanism underlying such translation remain to be elucidated. Here, we characterize the MchSLE-1 translation mechanism. We found that the MchSLE-1 5' and 3'LTRs command transcription of sense and antisense RNAs, respectively. Using luciferase reporters commanded by the untranslated regions (UTRs) of MchSLE-1, we found that in vitro 5'UTR sense is unable to initiate translation, whereas the antisense 5'UTR initiates translation even when the eIF4E-eIF4G interaction was disrupted, suggesting the presence of an internal ribosomal entry site (IRES). The antisense 5'UTR IRES activity was tested using bicistronic reporters. The antisense 5'UTR has IRES activity only when the mRNA is transcribed in the nucleus, suggesting that nuclear RNA-binding proteins are required to modulate its activity. Indeed, heterogeneous nuclear ribonucleoprotein K (hnRNPK) was identified as an IRES trans-acting factor (ITAF) of the MchSLE-1 IRES. To our knowledge, this is the first report describing an IRES in an antisense mRNA derived from a mussel LTR-retrotransposon.
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Affiliation(s)
| | | | | | | | | | - Gloria Arriagada
- Instituto de Ciencias Biomedicas, Facultad de Medicina y Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago 83700071, Chile; (L.F.-G.); (C.A.-M.); (P.L.-Á.); (B.B.); (F.J.B.)
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7
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Brito Querido J, Díaz-López I, Ramakrishnan V. The molecular basis of translation initiation and its regulation in eukaryotes. Nat Rev Mol Cell Biol 2024; 25:168-186. [PMID: 38052923 DOI: 10.1038/s41580-023-00624-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2023] [Indexed: 12/07/2023]
Abstract
The regulation of gene expression is fundamental for life. Whereas the role of transcriptional regulation of gene expression has been studied for several decades, it has been clear over the past two decades that post-transcriptional regulation of gene expression, of which translation regulation is a major part, can be equally important. Translation can be divided into four main stages: initiation, elongation, termination and ribosome recycling. Translation is controlled mainly during its initiation, a process which culminates in a ribosome positioned with an initiator tRNA over the start codon and, thus, ready to begin elongation of the protein chain. mRNA translation has emerged as a powerful tool for the development of innovative therapies, yet the detailed mechanisms underlying the complex process of initiation remain unclear. Recent studies in yeast and mammals have started to shed light on some previously unclear aspects of this process. In this Review, we discuss the current state of knowledge on eukaryotic translation initiation and its regulation in health and disease. Specifically, we focus on recent advances in understanding the processes involved in assembling the 43S pre-initiation complex and its recruitment by the cap-binding complex eukaryotic translation initiation factor 4F (eIF4F) at the 5' end of mRNA. In addition, we discuss recent insights into ribosome scanning along the 5' untranslated region of mRNA and selection of the start codon, which culminates in joining of the 60S large subunit and formation of the 80S initiation complex.
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Affiliation(s)
- Jailson Brito Querido
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Irene Díaz-López
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - V Ramakrishnan
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK.
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8
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Tidu A, Martin F. The interplay between cis- and trans-acting factors drives selective mRNA translation initiation in eukaryotes. Biochimie 2024; 217:20-30. [PMID: 37741547 DOI: 10.1016/j.biochi.2023.09.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 07/20/2023] [Accepted: 09/14/2023] [Indexed: 09/25/2023]
Abstract
Translation initiation consists in the assembly of the small and large ribosomal subunits on the start codon. This important step directly modulates the general proteome in living cells. Recently, genome wide studies revealed unexpected translation initiation events from unsuspected novel open reading frames resulting in the synthesis of a so-called 'dark proteome'. Indeed, the identification of the start codon by the translation machinery is a critical step that defines the translational landscape of the cell. Therefore, translation initiation is a highly regulated process in all organisms. In this review, we focus on the various cis- and trans-acting factors that rule the regulation of translation initiation in eukaryotes. Recent discoveries have shown that the guidance of the translation machinery for the choice of the start codon require sophisticated molecular mechanisms. In particular, the 5'UTR and the coding sequences contain cis-acting elements that trigger the use of AUG codons but also non-AUG codons to initiate protein synthesis. The use of these alternative start codons is also largely influenced by numerous trans-acting elements that drive selective mRNA translation in response to environmental changes.
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Affiliation(s)
- Antonin Tidu
- Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire, Architecture et Réactivité de l'ARN, CNRS UPR9002, 2, allée Konrad Roentgen, F-67084 Strasbourg, France
| | - Franck Martin
- Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire, Architecture et Réactivité de l'ARN, CNRS UPR9002, 2, allée Konrad Roentgen, F-67084 Strasbourg, France.
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9
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Metkar M, Pepin CS, Moore MJ. Tailor made: the art of therapeutic mRNA design. Nat Rev Drug Discov 2024; 23:67-83. [PMID: 38030688 DOI: 10.1038/s41573-023-00827-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2023] [Indexed: 12/01/2023]
Abstract
mRNA medicine is a new and rapidly developing field in which the delivery of genetic information in the form of mRNA is used to direct therapeutic protein production in humans. This approach, which allows for the quick and efficient identification and optimization of drug candidates for both large populations and individual patients, has the potential to revolutionize the way we prevent and treat disease. A key feature of mRNA medicines is their high degree of designability, although the design choices involved are complex. Maximizing the production of therapeutic proteins from mRNA medicines requires a thorough understanding of how nucleotide sequence, nucleotide modification and RNA structure interplay to affect translational efficiency and mRNA stability. In this Review, we describe the principles that underlie the physical stability and biological activity of mRNA and emphasize their relevance to the myriad considerations that factor into therapeutic mRNA design.
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10
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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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11
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Zafirov D, Giovinazzo N, Lecampion C, Field B, Ducassou JN, Couté Y, Browning KS, Robaglia C, Gallois JL. Arabidopsis eIF4E1 protects the translational machinery during TuMV infection and restricts virus accumulation. PLoS Pathog 2023; 19:e1011417. [PMID: 37983287 PMCID: PMC10721207 DOI: 10.1371/journal.ppat.1011417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 12/14/2023] [Accepted: 10/23/2023] [Indexed: 11/22/2023] Open
Abstract
Successful subversion of translation initiation factors eIF4E determines the infection success of potyviruses, the largest group of viruses affecting plants. In the natural variability of many plant species, resistance to potyvirus infection is provided by polymorphisms at eIF4E that renders them inadequate for virus hijacking but still functional in translation initiation. In crops where such natural resistance alleles are limited, the genetic inactivation of eIF4E has been proposed for the engineering of potyvirus resistance. However, recent findings indicate that knockout eIF4E alleles may be deleterious for plant health and could jeopardize resistance efficiency in comparison to functional resistance proteins. Here, we explored the cause of these adverse effects by studying the role of the Arabidopsis eIF4E1, whose inactivation was previously reported as conferring resistance to the potyvirus clover yellow vein virus (ClYVV) while also promoting susceptibility to another potyvirus turnip mosaic virus (TuMV). We report that eIF4E1 is required to maintain global plant translation and to restrict TuMV accumulation during infection, and its absence is associated with a favoured virus multiplication over host translation. Furthermore, our findings show that, in the absence of eIF4E1, infection with TuMV results in the production of a truncated eIFiso4G1 protein. Finally, we demonstrate a role for eIFiso4G1 in TuMV accumulation and in supporting plant fitness during infection. These findings suggest that eIF4E1 counteracts the hijacking of the plant translational apparatus during TuMV infection and underscore the importance of preserving the functionality of translation initiation factors eIF4E when implementing potyvirus resistance strategies.
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Affiliation(s)
- Delyan Zafirov
- GAFL, INRAE, Montfavet, France
- Aix-Marseille Univ, CEA, CNRS, BIAM, LGBP Team, Marseille, France
| | | | - Cécile Lecampion
- Aix-Marseille Univ, CEA, CNRS, BIAM, LGBP Team, Marseille, France
| | - Ben Field
- Aix-Marseille Univ, CEA, CNRS, BIAM, LGBP Team, Marseille, France
| | | | - Yohann Couté
- Univ. Grenoble Alpes, INSERM, CEA, UA13 BGE, CNRS, CEA, Grenoble, France
| | - Karen S. Browning
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
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12
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Ariza-Mateos A, Briones C, Perales C, Bayo-Jiménez MT, Domingo E, Gómez J. Viruses as archaeological tools for uncovering ancient molecular relationships. Ann N Y Acad Sci 2023; 1529:3-13. [PMID: 37801367 DOI: 10.1111/nyas.15071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/08/2023]
Abstract
The entry of a virus into the host cell always implies the alteration of certain intracellular molecular relationships, some of which may involve the recovery of ancient cellular activities. In this sense, viruses are archaeological tools for identifying unexpressed activities in noninfected cells. Among these, activities that hinder virus propagation may represent cellular defense mechanisms, for example, activities that mutagenize the viral genome such as ADAR-1 or APOBEC activities. Instead, those that facilitate virus propagation can be interpreted as the result of viral adaptation to-or mimicking-cellular structures, enabling the virus to perform anthropomorphic activities, including hijacking, manipulating, and reorganizing cellular factors for their own benefit. The alternative we consider here is that some of these second set of cellular activities were already in the uninfected cell but silenced, under the negative control of the cell or lineage, and that they represent a necessary precondition for viral infection. For example, specifically loading an amino acid at the 3'-end of the mRNA of some plant viruses by aminoacyl-tRNA synthetases has proved essential for virus infection despite this reaction not occurring with cellular mRNAs. Other activities of this type are discussed here, together with the biological context in which they acquire a coherent meaning, that is, genetic latency and molecular conflict.
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Affiliation(s)
- Ascensión Ariza-Mateos
- Laboratory of RNA Archaeology, Instituto de Parasitología y Biomedicina "López-Neyra" (CSIC), Granada, Spain
| | - Carlos Briones
- Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Madrid, Spain
| | - Celia Perales
- Department of Molecular and Cell Biology, Centro Nacional de Biotecnología (CSIC), Madrid, Spain
| | - María Teresa Bayo-Jiménez
- Laboratory of RNA Archaeology, Instituto de Parasitología y Biomedicina "López-Neyra" (CSIC), Granada, Spain
| | - Esteban Domingo
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Madrid, Spain
| | - Jordi Gómez
- Laboratory of RNA Archaeology, Instituto de Parasitología y Biomedicina "López-Neyra" (CSIC), Granada, Spain
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13
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Cao Y, Liu H, Lu SS, Jones KA, Govind AP, Jeyifous O, Simmons CQ, Tabatabaei N, Green WN, Holder JL, Tahmasebi S, George AL, Dickinson BC. RNA-based translation activators for targeted gene upregulation. Nat Commun 2023; 14:6827. [PMID: 37884512 PMCID: PMC10603104 DOI: 10.1038/s41467-023-42252-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 10/04/2023] [Indexed: 10/28/2023] Open
Abstract
Technologies capable of programmable translation activation offer strategies to develop therapeutics for diseases caused by insufficient gene expression. Here, we present "translation-activating RNAs" (taRNAs), a bifunctional RNA-based molecular technology that binds to a specific mRNA of interest and directly upregulates its translation. taRNAs are constructed from a variety of viral or mammalian RNA internal ribosome entry sites (IRESs) and upregulate translation for a suite of target mRNAs. We minimize the taRNA scaffold to 94 nucleotides, identify two translation initiation factor proteins responsible for taRNA activity, and validate the technology by amplifying SYNGAP1 expression, a haploinsufficiency disease target, in patient-derived cells. Finally, taRNAs are suitable for delivery as RNA molecules by lipid nanoparticles (LNPs) to cell lines, primary neurons, and mouse liver in vivo. taRNAs provide a general and compact nucleic acid-based technology to upregulate protein production from endogenous mRNAs, and may open up possibilities for therapeutic RNA research.
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Affiliation(s)
- Yang Cao
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
| | - Huachun Liu
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
| | - Shannon S Lu
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
| | - Krysten A Jones
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
| | - Anitha P Govind
- Department of Neurobiology, The University of Chicago, Chicago, IL, USA
| | - Okunola Jeyifous
- Department of Neurobiology, The University of Chicago, Chicago, IL, USA
| | - Christine Q Simmons
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Negar Tabatabaei
- Department of Pharmacology and Regenerative Medicine, University of Illinois College of Medicine, Chicago, IL, USA
| | - William N Green
- Department of Neurobiology, The University of Chicago, Chicago, IL, USA
| | - Jimmy L Holder
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Soroush Tahmasebi
- Department of Pharmacology and Regenerative Medicine, University of Illinois College of Medicine, Chicago, IL, USA
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Bryan C Dickinson
- Department of Chemistry, The University of Chicago, Chicago, IL, USA.
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14
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Lidsky PV, Dmitriev SE, Andino R. Introduction of Dicistrovirus IRESs into UAS/SV40-polyA constructs results in premature polyadenylation and strong overexpression of the upstream ORF in Drosophila animals. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.04.560905. [PMID: 37873388 PMCID: PMC10592961 DOI: 10.1101/2023.10.04.560905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
To evaluate the properties of insect virus internal ribosomal entry sites (IRESs) for protein expression in Drosophila, we have introduced Cricket Paralysis virus (CrPV) and Drosophila C virus (DCV) IRESs into UAS/SV40-polyA vector. We found that introduction of IRESs induce premature polyadenylation, resulting in both truncation of the mRNA, and an increase in mRNA levels of approximately 40-fold. The increase in mRNA levels was accompanied by increased resistance to nonsense-mediated mRNA decay (NMD)-mediated degradation. Our results suggest that premature polyadenylation increases mRNA stability in the SV40 polyadenylation site-containing constructs, suggesting a novel method for robust overexpression of transgenes in Drosophila.
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Affiliation(s)
- Peter V. Lidsky
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, 94158, CA
| | - Sergey E. Dmitriev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Raul Andino
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, 94158, CA
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15
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Sherlock ME, Langeberg CJ, Segar KE, Kieft JS. A conserved class of viral RNA structures regulate translation reinitiation through dynamic ribosome interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.29.560040. [PMID: 37808774 PMCID: PMC10557763 DOI: 10.1101/2023.09.29.560040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Certain viral RNAs encode proteins downstream of the main protein coding region, expressed through "termination-reinitiation" events, dependent on RNA structure. RNA elements located upstream of the first stop codon within these viral mRNAs bind the ribosome, preventing ribosome recycling and inducing reinitiation. We used bioinformatic methods to identify new examples of viral reinitiation-stimulating RNAs and experimentally verified their secondary structure and function. We determined the structure of a representative viral RNA-ribosome complex using cryoEM. 3D classification and variability analyses reveal that the viral RNA structure can sample a range of conformations while remaining tethered to the ribosome, which enabling the ribosome to find a reinitiation start site within a limited range of mRNA sequence. Evaluating the conserved features and constraints of this entire RNA class in the context of the cryoEM reconstruction provides insight into mechanisms enabling reinitiation, a translation regulation strategy employed by many other viral and eukaryotic systems.
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16
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Abaeva IS, Young C, Warsaba R, Khan N, Tran L, Jan E, Pestova T, Hellen CT. The structure and mechanism of action of a distinct class of dicistrovirus intergenic region IRESs. Nucleic Acids Res 2023; 51:9294-9313. [PMID: 37427788 PMCID: PMC10516663 DOI: 10.1093/nar/gkad569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/06/2023] [Accepted: 06/22/2023] [Indexed: 07/11/2023] Open
Abstract
Internal ribosomal entry sites (IRESs) engage with the eukaryotic translation apparatus to promote end-independent initiation. We identified a conserved class of ∼150 nt long intergenic region (IGR) IRESs in dicistrovirus genomes derived from members of the phyla Arthropoda, Bryozoa, Cnidaria, Echinodermata, Entoprocta, Mollusca and Porifera. These IRESs, exemplified by Wenling picorna-like virus 2, resemble the canonical cricket paralysis virus (CrPV) IGR IRES in comprising two nested pseudoknots (PKII/PKIII) and a 3'-terminal pseudoknot (PKI) that mimics a tRNA anticodon stem-loop base-paired to mRNA. However, they are ∼50 nt shorter than CrPV-like IRESs, and PKIII is an H-type pseudoknot that lacks the SLIV and SLV stem-loops that are primarily responsible for the affinity of CrPV-like IRESs for the 40S ribosomal subunit and that restrict initial binding of PKI to its aminoacyl (A) site. Wenling-class IRESs bound strongly to 80S ribosomes but only weakly to 40S subunits. Whereas CrPV-like IRESs must be translocated from the A site to the peptidyl (P) site by elongation factor 2 for elongation to commence, Wenling-class IRESs bound directly to the P site of 80S ribosomes, and decoding begins without a prior translocation step. A chimeric CrPV clone containing a Wenling-class IRES was infectious, confirming that the IRES functioned in cells.
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Affiliation(s)
- Irina S Abaeva
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY 11203, USA
| | - Christina Young
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Reid Warsaba
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Nadiyah Khan
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Lan Vy Tran
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Eric Jan
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Tatyana V Pestova
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY 11203, USA
| | - Christopher U T Hellen
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY 11203, USA
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17
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Buscà R, Onesto C, Egensperger M, Pouysségur J, Pagès G, Lenormand P. N-terminal alanine-rich (NTAR) sequences drive precise start codon selection resulting in elevated translation of multiple proteins including ERK1/2. Nucleic Acids Res 2023; 51:7714-7735. [PMID: 37414542 PMCID: PMC10450180 DOI: 10.1093/nar/gkad528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 06/12/2023] [Indexed: 07/08/2023] Open
Abstract
We report the discovery of N-terminal alanine-rich sequences, which we term NTARs, that act in concert with their native 5'-untranslated regions to promote selection of the proper start codon. NTARs also facilitate efficient translation initiation while limiting the production of non-functional polypeptides through leaky scanning. We first identified NTARs in the ERK1/2 kinases, which are among the most important signaling molecules in mammals. Analysis of the human proteome reveals that hundreds of proteins possess NTARs, with housekeeping proteins showing a particularly high prevalence. Our data indicate that several of these NTARs act in a manner similar to those found in the ERKs and suggest a mechanism involving some or all of the following features: alanine richness, codon rarity, a repeated amino acid stretch and a nearby second AUG. These features may help slow down the leading ribosome, causing trailing pre-initiation complexes (PICs) to pause near the native AUG, thereby facilitating accurate translation initiation. Amplification of erk genes is frequently observed in cancer, and we show that NTAR-dependent ERK protein levels are a rate-limiting step for signal output. Thus, NTAR-mediated control of translation may reflect a cellular need to precisely control translation of key transcripts such as potential oncogenes. By preventing translation in alternative reading frames, NTAR sequences may be useful in synthetic biology applications, e.g. translation from RNA vaccines.
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Affiliation(s)
- Roser Buscà
- Université Côte d’Azur (UCA), CNRS UMR 7284 and INSERM U 1081, Institute for Research on Cancer and Aging Nice (IRCAN), 28 Avenue de Valombrose, 06107 Nice, France
- Centre Antoine Lacassagne, Nice, France
| | - Cercina Onesto
- Université Côte d’Azur (UCA), CNRS UMR 7284 and INSERM U 1081, Institute for Research on Cancer and Aging Nice (IRCAN), 28 Avenue de Valombrose, 06107 Nice, France
- Centre Antoine Lacassagne, Nice, France
- Polytech’Nice Sophia, Bioengineering Department, Sophia-Antipolis, France
| | - Mylène Egensperger
- Université Côte d’Azur (UCA), CNRS UMR 7284 and INSERM U 1081, Institute for Research on Cancer and Aging Nice (IRCAN), 28 Avenue de Valombrose, 06107 Nice, France
- Centre Antoine Lacassagne, Nice, France
| | - Jacques Pouysségur
- Université Côte d’Azur (UCA), CNRS UMR 7284 and INSERM U 1081, Institute for Research on Cancer and Aging Nice (IRCAN), 28 Avenue de Valombrose, 06107 Nice, France
- Centre Antoine Lacassagne, Nice, France
- Centre Scientifique de Monaco, Biomedical Department, Principality of Monaco
| | - Gilles Pagès
- Université Côte d’Azur (UCA), CNRS UMR 7284 and INSERM U 1081, Institute for Research on Cancer and Aging Nice (IRCAN), 28 Avenue de Valombrose, 06107 Nice, France
- Centre Antoine Lacassagne, Nice, France
- Centre Scientifique de Monaco, Biomedical Department, Principality of Monaco
| | - Philippe Lenormand
- Université Côte d’Azur (UCA), CNRS UMR 7284 and INSERM U 1081, Institute for Research on Cancer and Aging Nice (IRCAN), 28 Avenue de Valombrose, 06107 Nice, France
- Centre Antoine Lacassagne, Nice, France
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18
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Miścicka A, Lu K, Abaeva IS, Pestova TV, Hellen CUT. Initiation of translation on nedicistrovirus and related intergenic region IRESs by their factor-independent binding to the P site of 80S ribosomes. RNA (NEW YORK, N.Y.) 2023; 29:1051-1068. [PMID: 37041031 DOI: 10.1261/rna.079599.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/27/2023] [Indexed: 06/18/2023]
Abstract
Initiation of translation on many viral mRNAs occurs by noncanonical mechanisms that involve 5' end-independent binding of ribosomes to an internal ribosome entry site (IRES). The ∼190-nt-long intergenic region (IGR) IRES of dicistroviruses such as cricket paralysis virus (CrPV) initiates translation without Met-tRNAi Met or initiation factors. Advances in metagenomics have revealed numerous dicistrovirus-like genomes with shorter, structurally distinct IGRs, such as nedicistrovirus (NediV) and Antarctic picorna-like virus 1 (APLV1). Like canonical IGR IRESs, the ∼165-nt-long NediV-like IGRs comprise three domains, but they lack key canonical motifs, including L1.1a/L1.1b loops (which bind to the L1 stalk of the ribosomal 60S subunit) and the apex of stem-loop V (SLV) (which binds to the head of the 40S subunit). Domain 2 consists of a compact, highly conserved pseudoknot (PKIII) that contains a UACUA loop motif and a protruding CrPV-like stem--loop SLIV. In vitro reconstitution experiments showed that NediV-like IRESs initiate translation from a non-AUG codon and form elongation-competent 80S ribosomal complexes in the absence of initiation factors and Met-tRNAi Met Unlike canonical IGR IRESs, NediV-like IRESs bind directly to the peptidyl (P) site of ribosomes leaving the aminoacyl (A) site accessible for decoding. The related structures of NediV-like IRESs and their common mechanism of action indicate that they exemplify a distinct class of IGR IRES.
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Affiliation(s)
- Anna Miścicka
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York 11203, USA
| | - Kristen Lu
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York 11203, USA
| | - Irina S Abaeva
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York 11203, USA
| | - Tatyana V Pestova
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York 11203, USA
| | - Christopher U T Hellen
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York 11203, USA
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19
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Sherlock ME, Baquero Galvis L, Vicens Q, Kieft JS, Jagannathan S. Principles, mechanisms, and biological implications of translation termination-reinitiation. RNA (NEW YORK, N.Y.) 2023; 29:865-884. [PMID: 37024263 PMCID: PMC10275272 DOI: 10.1261/rna.079375.122] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 03/28/2023] [Indexed: 06/11/2023]
Abstract
The gene expression pathway from DNA sequence to functional protein is not as straightforward as simple depictions of the central dogma might suggest. Each step is highly regulated, with complex and only partially understood molecular mechanisms at play. Translation is one step where the "one gene-one protein" paradigm breaks down, as often a single mature eukaryotic mRNA leads to more than one protein product. One way this occurs is through translation reinitiation, in which a ribosome starts making protein from one initiation site, translates until it terminates at a stop codon, but then escapes normal recycling steps and subsequently reinitiates at a different downstream site. This process is now recognized as both important and widespread, but we are only beginning to understand the interplay of factors involved in termination, recycling, and initiation that cause reinitiation events. There appear to be several ways to subvert recycling to achieve productive reinitiation, different types of stresses or signals that trigger this process, and the mechanism may depend in part on where the event occurs in the body of an mRNA. This perspective reviews the unique characteristics and mechanisms of reinitiation events, highlights the similarities and differences between three major scenarios of reinitiation, and raises outstanding questions that are promising avenues for future research.
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Affiliation(s)
- Madeline E Sherlock
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Laura Baquero Galvis
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Quentin Vicens
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Jeffrey S Kieft
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Sujatha Jagannathan
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
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20
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Decombe A, El Kazzi P, Decroly E. Interplay of RNA 2'-O-methylations with viral replication. Curr Opin Virol 2023; 59:101302. [PMID: 36764118 DOI: 10.1016/j.coviro.2023.101302] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/06/2022] [Accepted: 12/19/2022] [Indexed: 02/11/2023]
Abstract
Viral RNAs (vRNAs) are decorated by post-transcriptional modifications, including methylation of nucleotides. Methylations regulate biological functions linked to the sequence, structure, and protein interactome of RNA. Several RNA viruses were found to harbor 2'-O-methylations, affecting the ribose moiety of RNA. This mark was initially shown to target the first and second nucleotides of the 5'-end cap structure of mRNA. More recently, nucleotides within vRNA were also reported to carry 2'-O-methylations. The consequences of such methylations are still puzzling since they were associated with both proviral and antiviral effects. Here, we focus on the mechanisms governing vRNA 2'-O-methylation and we explore the possible roles of this epitranscriptomic modification for viral replication.
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Affiliation(s)
- Alice Decombe
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288 Marseille Cedex 09, France
| | - Priscila El Kazzi
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288 Marseille Cedex 09, France
| | - Etienne Decroly
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288 Marseille Cedex 09, France.
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21
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Abstract
Viruses lack the properties to replicate independently due to the limited resources encoded in their genome; therefore, they hijack the host cell machinery to replicate and survive. Picornaviruses get the prerequisite for effective protein synthesis through specific sequences known as internal ribosome entry sites (IRESs). In the past 2 decades, significant progress has been made in identifying different types of IRESs in picornaviruses. This review will discuss the past and current findings related to the five different types of IRESs and various internal ribosome entry site trans-acting factors (ITAFs) that either promote or suppress picornavirus translation and replication. Some IRESs are inefficient and thus require ITAFs. To achieve their full efficiency, they recruit various ITAFs, which enable them to translate more effectively and efficiently, except type IV IRES, which does not require any ITAFs. Although there are two kinds of ITAFs, one promotes viral IRES-dependent translation, and the second type restricts. Picornaviruses IRESs are classified into five types based on their use of sequence, ITAFs, and initiation factors. Some ITAFs regulate IRES activity by localizing to the viral replication factories in the cytoplasm. Also, some drugs, chemicals, and herbal extracts also regulate viral IRES-dependent translation and replication. Altogether, this review will elaborate on our understanding of the past and recent advancements in the IRES-dependent translation and replication of picornaviruses. IMPORTANCE The family Picornaviridae is divided into 68 genera and 158 species. The viruses belonging to this family range from public health importance, such as poliovirus, enterovirus A71, and hepatitis A virus, to animal viruses of great economic importance, such as foot-and-mouth disease virus. The genomes of picornaviruses contain 5' untranslated regions (5' UTRs), which possess crucial and highly structured stem-loops known as IRESs. IRES assemble the ribosomes and facilitate the cap-independent translation. Virus-host interaction is a hot spot for researchers, which warrants deep insight into understanding viral pathogenesis better and discovering new tools and ways for viral restriction to improve human and animal health. The cap-independent translation in the majority of picornaviruses is modulated by ITAFs, which bind to various IRES regions to initiate the translation. The discoveries of ITAFs substantially contributed to understanding viral replication behavior and enhanced our knowledge about virus-host interaction more effectively than ever before. This review discussed the various types of IRESs found in Picornaviridae, past and present discoveries regarding ITAFs, and their mechanism of action. The herbal extracts, drugs, and chemicals, which indicated their importance in controlling viruses, were also summarized. In addition, we discussed the movement of ITAFs from the nucleus to viral replication factories. We believe this review will stimulate researchers to search for more novel ITAFs, drugs, herbal extracts, and chemicals, enhancing the understanding of virus-host interaction.
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Decle-Carrasco S, Rodríguez-Piña AL, Rodríguez-Zapata LC, Castano E. Current research on viral proteins that interact with fibrillarin. Mol Biol Rep 2023; 50:4631-4643. [PMID: 36928641 PMCID: PMC10018631 DOI: 10.1007/s11033-023-08343-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 02/15/2023] [Indexed: 03/18/2023]
Abstract
The nucleolus is a multifunctional nuclear domain primarily dedicated to ribosome biogenesis. Certain viruses developed strategies to manipulate host nucleolar proteins to facilitate their replication by modulating ribosomal RNA (rRNA) processing. This association interferes with nucleolar functions resulting in overactivation or arrest of ribosome biogenesis, induction or inhibition of apoptosis, and affecting stress response. The nucleolar protein fibrillarin (FBL) is an important target of some plant and animal viruses. FBL is an essential and highly conserved S-adenosyl methionine (SAM) dependent methyltransferase, capable of rRNA degradation by its intrinsically disordered region (IDR), the glycine/arginine-rich (GAR) domain. It forms a ribonucleoprotein complex that directs 2'-O-methylations in more than 100 sites of pre-rRNAs. It is involved in multiple cellular processes, including initiation of transcription, oncogenesis, and apoptosis, among others. The interaction with animal viruses, including human viruses, triggered its redistribution to the nucleoplasm and cytoplasm, interfering with its role in pre-rRNA processing. Viral-encoded proteins with IDRs as nucleocapsids, matrix, Tat protein, and even a viral snoRNA, can associate with FBL, forcing the nucleolar protein to undergo atypical functions. Here we review the molecular mechanisms employed by animal and human viruses to usurp FBL functions and the effect on cellular processes, particularly in ribosome biogenesis.
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Affiliation(s)
- Stefano Decle-Carrasco
- Unidad de Bioquímica y Biología Molecular de Plantas. Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida, Yucatán, México
| | - Alma Laura Rodríguez-Piña
- Unidad de Bioquímica y Biología Molecular de Plantas. Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida, Yucatán, México
| | - Luis Carlos Rodríguez-Zapata
- Unidad de Biotecnología. Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida, Yucatán, México
| | - Enrique Castano
- Unidad de Bioquímica y Biología Molecular de Plantas. Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida, Yucatán, México.
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23
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Shestakova ED, Smirnova VV, Shatsky IN, Terenin IM. Specific mechanisms of translation initiation in higher eukaryotes: the eIF4G2 story. RNA (NEW YORK, N.Y.) 2023; 29:282-299. [PMID: 36517212 PMCID: PMC9945437 DOI: 10.1261/rna.079462.122] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The eukaryotic initiation factor 4G2 (eIF4G2, DAP5, Nat1, p97) was discovered in 1997. Over the past two decades, dozens of papers have presented contradictory data on eIF4G2 function. Since its identification, eIF4G2 has been assumed to participate in noncanonical translation initiation mechanisms, but recent results indicate that it can be involved in scanning as well. In particular, eIF4G2 provides leaky scanning through some upstream open reading frames (uORFs), which are typical for long 5' UTRs of mRNAs from higher eukaryotes. It is likely the protein can also help the ribosome overcome other impediments during scanning of the 5' UTRs of animal mRNAs. This may explain the need for eIF4G2 in higher eukaryotes, as many mRNAs that encode regulatory proteins have rather long and highly structured 5' UTRs. Additionally, they often bind to various proteins, which also hamper the movement of scanning ribosomes. This review discusses the suggested mechanisms of eIF4G2 action, denotes obscure or inconsistent results, and proposes ways to uncover other fundamental mechanisms in which this important protein factor may be involved in higher eukaryotes.
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Affiliation(s)
- Ekaterina D Shestakova
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Victoria V Smirnova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Ivan N Shatsky
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Ilya M Terenin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
- Sirius University of Science and Technology, Sochi 354349, Russia
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Morishita EC. Discovery of RNA-targeted small molecules through the merging of experimental and computational technologies. Expert Opin Drug Discov 2023; 18:207-226. [PMID: 36322542 DOI: 10.1080/17460441.2022.2134852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION The field of RNA-targeted small molecules is rapidly evolving, owing to the advances in experimental and computational technologies. With the identification of several bioactive small molecules that target RNA, including the FDA-approved risdiplam, the biopharmaceutical industry is gaining confidence in the field. This review, based on the literature obtained from PubMed, aims to disseminate information about the various technologies developed for targeting RNA with small molecules and propose areas for improvement to develop drugs more efficiently, particularly those linked to diseases with unmet medical needs. AREAS COVERED The technologies for the identification of RNA targets, screening of chemical libraries against RNA, assessing the bioactivity and target engagement of the hit compounds, structure determination, and hit-to-lead optimization are reviewed. Along with the description of the technologies, their strengths, limitations, and examples of how they can impact drug discovery are provided. EXPERT OPINION Many existing technologies employed for protein targets have been repurposed for use in the discovery of RNA-targeted small molecules. In addition, technologies tailored for RNA targets have been developed. Nevertheless, more improvements are necessary, such as artificial intelligence to dissect important RNA structures and RNA-small-molecule interactions and more powerful chemical probing and structure prediction techniques.
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Archaea/eukaryote-specific ribosomal proteins - guardians of a complex structure. Comput Struct Biotechnol J 2023; 21:1249-1261. [PMID: 36817958 PMCID: PMC9932298 DOI: 10.1016/j.csbj.2023.01.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 01/09/2023] [Accepted: 01/26/2023] [Indexed: 01/29/2023] Open
Abstract
In three domains of life, proteins are synthesized by large ribonucleoprotein particles called ribosomes. All ribosomes are composed of ribosomal RNAs (rRNA) and numerous ribosomal proteins (r-protein). The three-dimensional shape of ribosomes is mainly defined by a tertiary structure of rRNAs. In addition, rRNAs have a major role in decoding the information carried by messenger RNAs and catalyzing the peptide bond formation. R-proteins are essential for shaping the network of interactions that contribute to a various aspects of the protein synthesis machinery, including assembly of ribosomes and interaction of ribosomal subunits. Structural studies have revealed that many key components of ribosomes are conserved in all life domains. Besides the core structure, ribosomes contain domain-specific structural features that include additional r-proteins and extensions of rRNA and r-proteins. This review focuses specifically on those r-proteins that are found only in archaeal and eukaryotic ribosomes. The role of these archaea/eukaryote specific r-proteins in stabilizing the ribosome structure is discussed. Several examples illustrate their functions in the formation of the internal network of ribosomal subunits and interactions between the ribosomal subunits. In addition, the significance of these r-proteins in ribosome biogenesis and protein synthesis is highlighted.
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26
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Takallou S, Puchacz N, Allard D, Said KB, Nokhbeh MR, Samanfar B, Golshani A. IRES-mediated translation in bacteria. Biochem Biophys Res Commun 2023; 641:110-115. [PMID: 36527744 DOI: 10.1016/j.bbrc.2022.12.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 12/07/2022] [Indexed: 12/14/2022]
Abstract
Despite the similarity in fundamental goals of translation initiation between different domains of life, it is one of the most phylogenetically diverse steps of the central dogma of molecular biology. In a classical view, the translation signals for prokaryotes and eukaryotes are distinct from each other. This idea was challenged by the finding that the Internal Ribosome Entry Site (IRES) belonging to Plautia stali intestine virus (PSIV) could bypass the domain-specific boundaries and effectively initiate translation in E. coli. This finding led us to investigate whether the ability of PSIV IRES to initiate translation in E. coli is specific to this IRES and also to study features that allow this viral IRES to mediate prokaryotic translation initiation. We observed that certain IRESs may also possess the ability to initiate E. coli translation. Our results also indicated that the structural integrity of the PSIV IRES in translation in prokaryotes does not appear to be as critical as it is in eukaryotes. We also demonstrated that two regions of the PSIV IRES with complementarity to 16S ribosomal RNA are important for the ability of this IRES to initiate translation in E. coli.
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Affiliation(s)
- Sarah Takallou
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada; Department of Biology, Carleton University, Ottawa, Ontario, Canada.
| | - Nathalie Puchacz
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada; Department of Biology, Carleton University, Ottawa, Ontario, Canada.
| | - Danielle Allard
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada; Department of Biology, Carleton University, Ottawa, Ontario, Canada.
| | - Kamaledin B Said
- Department of Pathology and Microbiology, College of Medicine, University of Hail, Saudi Arabia.
| | | | - Bahram Samanfar
- Department of Biology, Carleton University, Ottawa, Ontario, Canada; Agriculture and Agri-Food Canada, Ottawa Research and Development Centre (ORDC), Ottawa, Ontario, Canada.
| | - Ashkan Golshani
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada; Department of Biology, Carleton University, Ottawa, Ontario, Canada.
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Andreev DE, Niepmann M, Shatsky IN. Elusive Trans-Acting Factors Which Operate with Type I (Poliovirus-like) IRES Elements. Int J Mol Sci 2022; 23:ijms232415497. [PMID: 36555135 PMCID: PMC9778869 DOI: 10.3390/ijms232415497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 12/02/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022] Open
Abstract
The phenomenon of internal initiation of translation was discovered in 1988 on poliovirus mRNA. The prototypic cis-acting element in the 5' untranslated region (5'UTR) of poliovirus mRNA, which is able to direct initiation at an internal start codon without the involvement of a cap structure, has been called an IRES (Internal Ribosome Entry Site or Segment). Despite its early discovery, poliovirus and other related IRES elements of type I are poorly characterized, and it is not yet clear which host proteins (a.k.a. IRES trans-acting factors, ITAFs) are required for their full activity in vivo. Here we discuss recent and old results devoted to type I IRESes and provide evidence that Poly(rC) binding protein 2 (PCBP2), Glycyl-tRNA synthetase (GARS), and Cold Shock Domain Containing E1 (CSDE1, also known as UNR) are major regulators of type I IRES activity.
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Affiliation(s)
- Dmitry E. Andreev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Michael Niepmann
- Institute of Biochemistry, Medical Faculty, Justus-Liebig-University, 35392 Giessen, Germany
| | - Ivan N. Shatsky
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
- Correspondence:
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28
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Condé L, Allatif O, Ohlmann T, de Breyne S. Translation of SARS-CoV-2 gRNA Is Extremely Efficient and Competitive despite a High Degree of Secondary Structures and the Presence of an uORF. Viruses 2022; 14:1505. [PMID: 35891485 PMCID: PMC9322171 DOI: 10.3390/v14071505] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/06/2022] [Accepted: 07/07/2022] [Indexed: 12/15/2022] Open
Abstract
The SARS-CoV-2 infection generates up to nine different sub-genomic mRNAs (sgRNAs), in addition to the genomic RNA (gRNA). The 5'UTR of each viral mRNA shares the first 75 nucleotides (nt.) at their 5'end, called the leader, but differentiates by a variable sequence (0 to 190 nt. long) that follows the leader. As a result, each viral mRNA has its own specific 5'UTR in term of length, RNA structure, uORF and Kozak context; each one of these characteristics could affect mRNA expression. In this study, we have measured and compared translational efficiency of each of the ten viral transcripts. Our data show that most of them are very efficiently translated in all translational systems tested. Surprisingly, the gRNA 5'UTR, which is the longest and the most structured, was also the most efficient to initiate translation. This property is conserved in the 5'UTR of SARS-CoV-1 but not in MERS-CoV strain, mainly due to the regulation imposed by the uORF. Interestingly, the translation initiation mechanism on the SARS-CoV-2 gRNA 5'UTR requires the cap structure and the components of the eIF4F complex but showed no dependence in the presence of the poly(A) tail in vitro. Our data strongly suggest that translation initiation on SARS-CoV-2 mRNAs occurs via an unusual cap-dependent mechanism.
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Affiliation(s)
| | | | - Théophile Ohlmann
- CIRI, Centre International de Recherche en Infectiologie, (Team Ohlmann), Univ Lyon, Inserm U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, ENS de Lyon, F-69007 Lyon, France; (L.C.); (O.A.)
| | - Sylvain de Breyne
- CIRI, Centre International de Recherche en Infectiologie, (Team Ohlmann), Univ Lyon, Inserm U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, ENS de Lyon, F-69007 Lyon, France; (L.C.); (O.A.)
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29
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Francisco-Velilla R, Embarc-Buh A, Abellan S, Martinez-Salas E. Picornavirus translation strategies. FEBS Open Bio 2022; 12:1125-1141. [PMID: 35313388 PMCID: PMC9157412 DOI: 10.1002/2211-5463.13400] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/02/2022] [Accepted: 03/18/2022] [Indexed: 12/15/2022] Open
Abstract
The genome of viruses classified as picornaviruses consists of a single monocistronic positive strand RNA. The coding capacity of these RNA viruses is rather limited, and thus, they rely on the cellular machinery for their viral replication cycle. Upon the entry of the virus into susceptible cells, the viral RNA initially competes with cellular mRNAs for access to the protein synthesis machinery. Not surprisingly, picornaviruses have evolved specialized strategies that successfully allow the expression of viral gene products, which we outline in this review. The main feature of all picornavirus genomes is the presence of a heavily structured RNA element on the 5´UTR, referred to as an internal ribosome entry site (IRES) element, which directs viral protein synthesis as well and, consequently, triggers the subsequent steps required for viral replication. Here, we will summarize recent studies showing that picornavirus IRES elements consist of a modular structure, providing sites of interaction for ribosome subunits, eIFs, and a selective group of RNA‐binding proteins.
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Affiliation(s)
| | - Azman Embarc-Buh
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | - Salvador Abellan
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
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A Split NanoLuc Reporter Quantitatively Measures Circular RNA IRES Translation. Genes (Basel) 2022; 13:genes13020357. [PMID: 35205400 PMCID: PMC8871761 DOI: 10.3390/genes13020357] [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: 01/13/2022] [Revised: 02/08/2022] [Accepted: 02/09/2022] [Indexed: 02/02/2023] Open
Abstract
Internal ribosomal entry sites (IRESs) are RNA secondary structures that mediate translation independent from the m7G RNA cap. The dicistronic luciferase assay is the most frequently used method to measure IRES-mediated translation. While this assay is quantitative, it requires numerous controls and can be time-consuming. Circular RNAs generated by splinted ligation have been shown to also accurately report on IRES-mediated translation, however suffer from low yield and other challenges. More recently, cellular sequences were shown to facilitate RNA circle formation through backsplicing. Here, we used a previously published backsplicing circular RNA split GFP reporter to create a highly sensitive and quantitative split nanoluciferase (NanoLuc) reporter. We show that NanoLuc expression requires backsplicing and correct orientation of a bona fide IRES. In response to cell stress, IRES-directed NanoLuc expression remained stable or increased while a capped control reporter decreased in translation. In addition, we detected NanoLuc expression from putative cellular IRESs and the Zika virus 5' untranslated region that is proposed to harbor IRES function. These data together show that our IRES reporter construct can be used to verify, identify and quantify the ability of sequences to mediate IRES-translation within a circular RNA.
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31
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Tau mRNA Metabolism in Neurodegenerative Diseases: A Tangle Journey. Biomedicines 2022; 10:biomedicines10020241. [PMID: 35203451 PMCID: PMC8869323 DOI: 10.3390/biomedicines10020241] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/17/2022] [Accepted: 01/18/2022] [Indexed: 12/07/2022] Open
Abstract
Tau proteins are known to be mainly involved in regulation of microtubule dynamics. Besides this function, which is critical for axonal transport and signal transduction, tau proteins also have other roles in neurons. Moreover, tau proteins are turned into aggregates and consequently trigger many neurodegenerative diseases termed tauopathies, of which Alzheimer’s disease (AD) is the figurehead. Such pathological aggregation processes are critical for the onset of these diseases. Among the various causes of tau protein pathogenicity, abnormal tau mRNA metabolism, expression and dysregulation of tau post-translational modifications are critical steps. Moreover, the relevance of tau function to general mRNA metabolism has been highlighted recently in tauopathies. In this review, we mainly focus on how mRNA metabolism impacts the onset and development of tauopathies. Thus, we intend to portray how mRNA metabolism of, or mediated by, tau is associated with neurodegenerative diseases.
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32
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RNA-Binding Proteins as Regulators of Internal Initiation of Viral mRNA Translation. Viruses 2022; 14:v14020188. [PMID: 35215780 PMCID: PMC8879377 DOI: 10.3390/v14020188] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/03/2022] [Accepted: 01/14/2022] [Indexed: 12/17/2022] Open
Abstract
Viruses are obligate intracellular parasites that depend on the host’s protein synthesis machinery for translating their mRNAs. The viral mRNA (vRNA) competes with the host mRNA to recruit the translational machinery, including ribosomes, tRNAs, and the limited eukaryotic translation initiation factor (eIFs) pool. Many viruses utilize non-canonical strategies such as targeting host eIFs and RNA elements known as internal ribosome entry sites (IRESs) to reprogram cellular gene expression, ensuring preferential translation of vRNAs. In this review, we discuss vRNA IRES-mediated translation initiation, highlighting the role of RNA-binding proteins (RBPs), other than the canonical translation initiation factors, in regulating their activity.
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33
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The hinge region of the Israeli acute paralysis virus internal ribosome entry site directs ribosomal positioning, translational activity and virus infection. J Virol 2022; 96:e0133021. [PMID: 35019716 DOI: 10.1128/jvi.01330-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
All viruses must usurp host ribosomes for viral protein synthesis. Dicistroviruses utilize an InterGenic Region Internal Ribosome Entry Site (IGR IRES) to directly recruit ribosomes and mediate translation initiation from a non-AUG start codon. The IGR IRES adopts a three-pseudoknot structure that is comprised of a ribosome binding domain of pseudoknot II and III (PKII and PKIII), and a tRNA-like anticodon domain (PKI) connected via a short, one to three nucleotide hinge region. Recent cryo-EM structural analysis of the dicistrovirus Taura syndrome virus (TSV) IGR IRES bound to the ribosome suggests that the hinge region may facilitate translocation of the IRES from the ribosomal A to P site. In this study, we provide mechanistic and functional insights into the role of the hinge region in IGR IRES translation. Using the honeybee dicistrovirus, Israeli acute paralysis virus (IAPV), as a model, we demonstrate that mutations of the hinge region resulted in decreased IRES-dependent translation in vitro. Toeprinting primer extension analysis of mutant IRESs bound to purified ribosomes and in rabbit reticulocyte lysates showed defects in the initial ribosome positioning on the IRES. Finally, using a hybrid dicistrovirus clone, mutations in the hinge region of the IAPV IRES resulted in decreased viral yield. Our work reveals an unexpected role of the hinge region of the dicistrovirus IGR IRES coordinating the two independently folded domains of the IRES to properly position the ribosome to start translation. IMPORTANCE Viruses must use the host cell machinery to direct viral protein expression for productive infection. One such mechanism is an internal ribosome entry site which can directly recruit host cell machinery. In this study, we have identified a novel sequence in an IRES that provides insight into the mechanism of viral gene expression. Specifically, this novel sequence promotes viral IRES activity by directly guiding the host cell machinery to start gene expression at a specific site.
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Arhab Y, Miścicka A, Pestova TV, Hellen CUT. Horizontal gene transfer as a mechanism for the promiscuous acquisition of distinct classes of IRES by avian caliciviruses. Nucleic Acids Res 2021; 50:1052-1068. [PMID: 34928389 PMCID: PMC8789048 DOI: 10.1093/nar/gkab1243] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 11/17/2021] [Accepted: 12/15/2021] [Indexed: 02/05/2023] Open
Abstract
In contrast to members of Picornaviridae which have long 5'-untranslated regions (5'UTRs) containing internal ribosomal entry sites (IRESs) that form five distinct classes, members of Caliciviridae typically have short 5'UTRs and initiation of translation on them is mediated by interaction of the viral 5'-terminal genome-linked protein (VPg) with subunits of eIF4F rather than by an IRES. The recent description of calicivirus genomes with 500-900nt long 5'UTRs was therefore unexpected and prompted us to examine them in detail. Sequence analysis and structural modelling of the atypically long 5'UTRs of Caliciviridae sp. isolate yc-13 and six other caliciviruses suggested that they contain picornavirus-like type 2 IRESs, whereas ruddy turnstone calicivirus (RTCV) and Caliciviridae sp. isolate hwf182cal1 calicivirus contain type 4 and type 5 IRESs, respectively. The suggestion that initiation on RTCV mRNA occurs by the type 4 IRES mechanism was confirmed experimentally using in vitro reconstitution. The high sequence identity between identified calicivirus IRESs and specific picornavirus IRESs suggests a common evolutionary origin. These calicivirus IRESs occur in a single phylogenetic branch of Caliciviridae and were likely acquired by horizontal gene transfer.
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Affiliation(s)
- Yani Arhab
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn NY 11203, USA
| | - Anna Miścicka
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn NY 11203, USA
| | - Tatyana V Pestova
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn NY 11203, USA
| | - Christopher U T Hellen
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn NY 11203, USA
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Gilmer O, Quignon E, Jousset AC, Paillart JC, Marquet R, Vivet-Boudou V. Chemical and Enzymatic Probing of Viral RNAs: From Infancy to Maturity and Beyond. Viruses 2021; 13:1894. [PMID: 34696322 PMCID: PMC8537439 DOI: 10.3390/v13101894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 09/13/2021] [Accepted: 09/16/2021] [Indexed: 11/17/2022] Open
Abstract
RNA molecules are key players in a variety of biological events, and this is particularly true for viral RNAs. To better understand the replication of those pathogens and try to block them, special attention has been paid to the structure of their RNAs. Methods to probe RNA structures have been developed since the 1960s; even if they have evolved over the years, they are still in use today and provide useful information on the folding of RNA molecules, including viral RNAs. The aim of this review is to offer a historical perspective on the structural probing methods used to decipher RNA structures before the development of the selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) methodology and to show how they have influenced the current probing techniques. Actually, these technological breakthroughs, which involved advanced detection methods, were made possible thanks to the development of next-generation sequencing (NGS) but also to the previous works accumulated in the field of structural RNA biology. Finally, we will also discuss how high-throughput SHAPE (hSHAPE) paved the way for the development of sophisticated RNA structural techniques.
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Affiliation(s)
| | | | | | | | - Roland Marquet
- Université de Strasbourg, CNRS, Architecture et Réactivité de l’ARN, UPR9002, F-67000 Strasbourg, France; (O.G.); (E.Q.); (A.-C.J.); (J.-C.P.)
| | - Valérie Vivet-Boudou
- Université de Strasbourg, CNRS, Architecture et Réactivité de l’ARN, UPR9002, F-67000 Strasbourg, France; (O.G.); (E.Q.); (A.-C.J.); (J.-C.P.)
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36
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Abdullah SW, Wu J, Zhang Y, Bai M, Guan J, Liu X, Sun S, Guo H. DDX21, a Host Restriction Factor of FMDV IRES-Dependent Translation and Replication. Viruses 2021; 13:v13091765. [PMID: 34578346 PMCID: PMC8473184 DOI: 10.3390/v13091765] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 08/23/2021] [Accepted: 08/27/2021] [Indexed: 12/13/2022] Open
Abstract
In cells, the contributions of DEAD-box helicases (DDXs), without which cellular life is impossible, are of utmost importance. The extremely diverse roles of the nucleolar helicase DDX21, ranging from fundamental cellular processes such as cell growth, ribosome biogenesis, protein translation, protein–protein interaction, mediating and sensing transcription, and gene regulation to viral manipulation, drew our attention. We designed this project to study virus–host interactions and viral pathogenesis. A pulldown assay was used to investigate the association between foot-and-mouth disease virus (FMDV) and DDX21. Further insight into the DDX21–FMDV interaction was obtained through dual-luciferase, knockdown, overexpression, qPCR, and confocal microscopy assays. Our results highlight the antagonistic feature of DDX21 against FMDV, as it progressively inhibited FMDV internal ribosome entry site (IRES) -dependent translation through association with FMDV IRES domains 2, 3, and 4. To subvert this host helicase antagonism, FMDV degraded DDX21 through its non-structural proteins 2B, 2C, and 3C protease (3Cpro). Our results suggest that DDX21 is degraded during 2B and 2C overexpression and FMDV infection through the caspase pathway; however, DDX21 is degraded through the lysosomal pathway during 3Cpro overexpression. Further investigation showed that DDX21 enhanced interferon-beta and interleukin-8 production to restrict viral replication. Together, our results demonstrate that DDX21 is a novel FMDV IRES trans-acting factor, which negatively regulates FMDV IRES-dependent translation and replication.
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Affiliation(s)
| | | | | | | | | | | | - Shiqi Sun
- Correspondence: (S.S.); (H.G.); Tel.: +86-0931-8312213 (S.S. & H.G.)
| | - Huichen Guo
- Correspondence: (S.S.); (H.G.); Tel.: +86-0931-8312213 (S.S. & H.G.)
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37
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Sorokin II, Vassilenko KS, Terenin IM, Kalinina NO, Agol VI, Dmitriev SE. Non-Canonical Translation Initiation Mechanisms Employed by Eukaryotic Viral mRNAs. BIOCHEMISTRY. BIOKHIMIIA 2021; 86:1060-1094. [PMID: 34565312 PMCID: PMC8436584 DOI: 10.1134/s0006297921090042] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 08/04/2021] [Accepted: 08/04/2021] [Indexed: 12/12/2022]
Abstract
Viruses exploit the translation machinery of an infected cell to synthesize their proteins. Therefore, viral mRNAs have to compete for ribosomes and translation factors with cellular mRNAs. To succeed, eukaryotic viruses adopt multiple strategies. One is to circumvent the need for m7G-cap through alternative instruments for ribosome recruitment. These include internal ribosome entry sites (IRESs), which make translation independent of the free 5' end, or cap-independent translational enhancers (CITEs), which promote initiation at the uncapped 5' end, even if located in 3' untranslated regions (3' UTRs). Even if a virus uses the canonical cap-dependent ribosome recruitment, it can still perturb conventional ribosomal scanning and start codon selection. The pressure for genome compression often gives rise to internal and overlapping open reading frames. Their translation is initiated through specific mechanisms, such as leaky scanning, 43S sliding, shunting, or coupled termination-reinitiation. Deviations from the canonical initiation reduce the dependence of viral mRNAs on translation initiation factors, thereby providing resistance to antiviral mechanisms and cellular stress responses. Moreover, viruses can gain advantage in a competition for the translational machinery by inactivating individual translational factors and/or replacing them with viral counterparts. Certain viruses even create specialized intracellular "translation factories", which spatially isolate the sites of their protein synthesis from cellular antiviral systems, and increase availability of translational components. However, these virus-specific mechanisms may become the Achilles' heel of a viral life cycle. Thus, better understanding of the unconventional mechanisms of viral mRNA translation initiation provides valuable insight for developing new approaches to antiviral therapy.
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Affiliation(s)
- Ivan I Sorokin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - Konstantin S Vassilenko
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Ilya M Terenin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia
| | - Natalia O Kalinina
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - Vadim I Agol
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia
- Institute of Poliomyelitis, Chumakov Center for Research and Development of Immunobiological Products, Russian Academy of Sciences, Moscow, 108819, Russia
| | - Sergey E Dmitriev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia.
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, 119234, Russia
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Han S, Wang X, Guan J, Wu J, Zhang Y, Li P, Liu Z, Abdullah SW, Zhang Z, Jin Y, Sun S, Guo H. Nucleolin Promotes IRES-Driven Translation of Foot-and-Mouth Disease Virus by Supporting the Assembly of Translation Initiation Complexes. J Virol 2021; 95:e0023821. [PMID: 33853964 PMCID: PMC8315980 DOI: 10.1128/jvi.00238-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 04/06/2021] [Indexed: 12/12/2022] Open
Abstract
Nucleolin (NCL), a stress-responsive RNA-binding protein, has been implicated in the translation of internal ribosome entry site (IRES)-containing mRNAs, which encode proteins involved in cell proliferation, carcinogenesis, and viral infection (type I IRESs). However, the details of the mechanisms by which NCL participates in IRES-driven translation have not hitherto been described. Here, we identified NCL as a protein that interacts with the IRES of foot-and-mouth disease virus (FMDV), which is a type II IRES. We also mapped the interactive regions within FMDV IRES and NCL in vitro. We found that NCL serves as a substantial regulator of FMDV IRES-driven translation but not of bulk cellular or vesicular stomatitis virus cap-dependent translation. NCL also modulates the translation of and infection by Seneca Valley virus (type III-like IRES) and classical swine fever virus (type III IRES), which suggests that its function is conserved in unrelated IRES-containing viruses. We also show that NCL affects viral replication by directly regulating the production of viral proteins and indirectly regulating FMDV RNA synthesis. Importantly, we observed that the cytoplasmic relocalization of NCL during FMDV infection is a substantial step for viral IRES-driven translation and that NCL specifically promotes the initiation phase of the translation process by recruiting translation initiation complexes to viral IRES. Finally, the functional importance of NCL in FMDV pathogenicity was confirmed in vivo. Taken together, our findings demonstrate a specific function for NCL in selective mRNA translation and identify a target for the development of a broad-spectrum class of antiviral interventions. IMPORTANCE FMDV usurps the cellular translation machinery to initiate viral protein synthesis via a mechanism driven by IRES elements. It allows the virus to shut down bulk cellular translation, while providing an advantage for its own gene expression. With limited coding capacity in its own genome, FMDV has evolved a mechanism to hijack host proteins to promote the recruitment of the host translation machinery, a process that is still not well understood. Here, we identified nucleolin (NCL) as a positive regulator of the IRES-driven translation of FMDV. Our study supports a model in which NCL relocalizes from the nucleus to the cytoplasm during the course of FMDV infection, where the cytoplasmic NCL promotes FMDV IRES-driven translation by bridging the translation initiation complexes with viral IRES. Our study demonstrates a previously uncharacterized role of NCL in the translation initiation of IRES-containing viruses, with important implications for the development of broad antiviral interventions.
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Affiliation(s)
- Shichong Han
- State Key Laboratory of Veterinary Etiological Biology, OIE/China National Foot-and-Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, People’s Republic of China
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, China Agricultural University, Beijing, People’s Republic of China
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, People’s Republic of China
| | - Xiaojia Wang
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, China Agricultural University, Beijing, People’s Republic of China
| | - Junyong Guan
- State Key Laboratory of Veterinary Etiological Biology, OIE/China National Foot-and-Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, People’s Republic of China
| | - Jinen Wu
- State Key Laboratory of Veterinary Etiological Biology, OIE/China National Foot-and-Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, People’s Republic of China
| | - Yun Zhang
- State Key Laboratory of Veterinary Etiological Biology, OIE/China National Foot-and-Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, People’s Republic of China
| | - Pinghua Li
- State Key Laboratory of Veterinary Etiological Biology, OIE/China National Foot-and-Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, People’s Republic of China
| | - Zaixin Liu
- State Key Laboratory of Veterinary Etiological Biology, OIE/China National Foot-and-Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, People’s Republic of China
| | - Sahibzada Waheed Abdullah
- State Key Laboratory of Veterinary Etiological Biology, OIE/China National Foot-and-Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, People’s Republic of China
| | - Zhihui Zhang
- State Key Laboratory of Veterinary Etiological Biology, OIE/China National Foot-and-Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, People’s Republic of China
| | - Ye Jin
- State Key Laboratory of Veterinary Etiological Biology, OIE/China National Foot-and-Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, People’s Republic of China
| | - Shiqi Sun
- State Key Laboratory of Veterinary Etiological Biology, OIE/China National Foot-and-Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, People’s Republic of China
| | - Huichen Guo
- State Key Laboratory of Veterinary Etiological Biology, OIE/China National Foot-and-Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, People’s Republic of China
- College of Animal Science, Yangtze University, Jingzhou, Hubei, People’s Republic of China
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Miao Z, Tidu A, Eriani G, Martin F. Secondary structure of the SARS-CoV-2 5'-UTR. RNA Biol 2021; 18:447-456. [PMID: 32965173 PMCID: PMC7544965 DOI: 10.1080/15476286.2020.1814556] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/22/2020] [Accepted: 08/19/2020] [Indexed: 02/06/2023] Open
Abstract
The SARS-CoV-2, a positive-sense single-stranded RNA Coronavirus, is a global threat to human health. Thus, understanding its life cycle mechanistically would be important to facilitate the design of antiviral drugs. A key aspect of viral progression is the synthesis of viral proteins by the ribosome of the human host. In Coronaviruses, this process is regulated by the viral 5' and 3' untranslated regions (UTRs), but the precise regulatory mechanism has not yet been well understood. In particular, the 5'-UTR of the viral genome is most likely involved in translation initiation of viral proteins. Here, we performed inline probing and RNase V1 probing to establish a model of the secondary structure of SARS-CoV-2 5'-UTR. We found that the 5'-UTR contains stable structures including a very stable four-way junction close to the AUG start codon. Sequence alignment analysis of SARS-CoV-2 variants 5'-UTRs revealed a highly conserved structure with few co-variations that confirmed our secondary structure model based on probing experiments.
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Affiliation(s)
- Zhichao Miao
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, UK
- Translational Research Institute of Brain and Brain-Like Intelligence and Department of Anesthesiology, Shanghai Fourth People’s Hospital Affiliated to Tongji University School of Medicine, Shanghai, China
- Newcastle Fibrosis Research Group, Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Antonin Tidu
- Architecture Et Réactivité De l’ARN, Université De Strasbourg, Institut De Biologie Moléculaire Et Cellulaire Du CNRS, Strasbourg, France
| | - Gilbert Eriani
- Architecture Et Réactivité De l’ARN, Université De Strasbourg, Institut De Biologie Moléculaire Et Cellulaire Du CNRS, Strasbourg, France
| | - Franck Martin
- Architecture Et Réactivité De l’ARN, Université De Strasbourg, Institut De Biologie Moléculaire Et Cellulaire Du CNRS, Strasbourg, France
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40
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Wang X, Vlok M, Flibotte S, Jan E. Resurrection of a Viral Internal Ribosome Entry Site from a 700 Year Old Ancient Northwest Territories Cripavirus. Viruses 2021; 13:v13030493. [PMID: 33802878 PMCID: PMC8002689 DOI: 10.3390/v13030493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 03/12/2021] [Accepted: 03/13/2021] [Indexed: 11/16/2022] Open
Abstract
The dicistrovirus intergenic region internal ribosome entry site (IGR IRES) uses an unprecedented, streamlined mechanism whereby the IRES adopts a triple-pseudoknot (PK) structure to directly bind to the conserved core of the ribosome and drive translation from a non-AUG codon. The origin of this IRES mechanism is not known. Previously, a partial fragment of a divergent dicistrovirus RNA genome, named ancient Northwest territories cripavirus (aNCV), was extracted from 700-year-old caribou feces trapped in a subarctic ice patch. The aNCV IGR sequence adopts a secondary structure similar to contemporary IGR IRES structures, however, there are subtle differences including 105 nucleotides upstream of the IRES of unknown function. Using filter binding assays, we showed that the aNCV IRES could bind to purified ribosomes, and toeprinting analysis pinpointed the start site at a GCU alanine codon adjacent to PKI. Using a bicistronic reporter RNA, the aNCV IGR can direct translation in vitro in a PKI-dependent manner. Lastly, a chimeric infectious clone swapping in the aNCV IRES supported translation and virus infection. The characterization and resurrection of a functional IGR IRES from a divergent 700-year-old virus provides a historical framework for the importance of this viral translational mechanism.
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Affiliation(s)
- Xinying Wang
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; (X.W.); (M.V.)
| | - Marli Vlok
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; (X.W.); (M.V.)
| | - Stephane Flibotte
- UBC/LSI Bioinformatics Facility, University of British Columbia, Vancouver, BC V6T 1Z3, Canada;
| | - Eric Jan
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; (X.W.); (M.V.)
- Correspondence: ; Tel.: +1-604-827-4226
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Targeting the DEAD-Box RNA Helicase eIF4A with Rocaglates-A Pan-Antiviral Strategy for Minimizing the Impact of Future RNA Virus Pandemics. Microorganisms 2021; 9:microorganisms9030540. [PMID: 33807988 PMCID: PMC8001013 DOI: 10.3390/microorganisms9030540] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/01/2021] [Accepted: 03/02/2021] [Indexed: 12/17/2022] Open
Abstract
The increase in pandemics caused by RNA viruses of zoonotic origin highlights the urgent need for broad-spectrum antivirals against novel and re-emerging RNA viruses. Broad-spectrum antivirals could be deployed as first-line interventions during an outbreak while virus-specific drugs and vaccines are developed and rolled out. Viruses depend on the host’s protein synthesis machinery for replication. Several natural compounds that target the cellular DEAD-box RNA helicase eIF4A, a key component of the eukaryotic translation initiation complex eIF4F, have emerged as potential broad-spectrum antivirals. Rocaglates, a group of flavaglines of plant origin that clamp mRNAs with highly structured 5′ untranslated regions (5′UTRs) onto the surface of eIF4A through specific stacking interactions, exhibit the largest selectivity and potential therapeutic indices among all known eIF4A inhibitors. Their unique mechanism of action limits the inhibitory effect of rocaglates to the translation of eIF4A-dependent viral mRNAs and a minor fraction of host mRNAs exhibiting stable RNA secondary structures and/or polypurine sequence stretches in their 5′UTRs, resulting in minimal potential toxic side effects. Maintaining a favorable safety profile while inducing efficient inhibition of a broad spectrum of RNA viruses makes rocaglates into primary candidates for further development as pan-antiviral therapeutics.
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Girardi E, Pfeffer S, Baumert TF, Majzoub K. Roadblocks and fast tracks: How RNA binding proteins affect the viral RNA journey in the cell. Semin Cell Dev Biol 2021; 111:86-100. [PMID: 32847707 PMCID: PMC7443355 DOI: 10.1016/j.semcdb.2020.08.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 08/14/2020] [Accepted: 08/14/2020] [Indexed: 12/12/2022]
Abstract
As obligate intracellular parasites with limited coding capacity, RNA viruses rely on host cells to complete their multiplication cycle. Viral RNAs (vRNAs) are central to infection. They carry all the necessary information for a virus to synthesize its proteins, replicate and spread and could also play essential non-coding roles. Regardless of its origin or tropism, vRNA has by definition evolved in the presence of host RNA Binding Proteins (RBPs), which resulted in intricate and complicated interactions with these factors. While on one hand some host RBPs recognize vRNA as non-self and mobilize host antiviral defenses, vRNA must also co-opt other host RBPs to promote viral infection. Focusing on pathogenic RNA viruses, we will review important scenarios of RBP-vRNA interactions during which host RBPs recognize, modify or degrade vRNAs. We will then focus on how vRNA hijacks the largest ribonucleoprotein complex (RNP) in the cell, the ribosome, to selectively promote the synthesis of its proteins. We will finally reflect on how novel technologies are helping in deepening our understanding of vRNA-host RBPs interactions, which can be ultimately leveraged to combat everlasting viral threats.
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Affiliation(s)
- Erika Girardi
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France
| | - Sebastien Pfeffer
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France
| | - Thomas F Baumert
- Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Université de Strasbourg, 67000, Strasbourg, France; Pole Hépatodigestif, Institut Hopitalo-universitaire, Hopitaux Universitaires de Strasbourg, 67000 Strasbourg, France
| | - Karim Majzoub
- Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Université de Strasbourg, 67000, Strasbourg, France.
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43
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Saiz M, Martinez-Salas E. Uncovering targets of the Leader protease: Linking RNA-mediated pathways and antiviral defense. WILEY INTERDISCIPLINARY REVIEWS-RNA 2021; 12:e1645. [PMID: 33605051 PMCID: PMC8244099 DOI: 10.1002/wrna.1645] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/19/2021] [Accepted: 01/20/2021] [Indexed: 12/12/2022]
Abstract
RNA viruses have developed specialized mechanisms to subvert host RNA‐binding proteins (RBPs) favoring their own gene expression. The Leader (L) protein of foot‐and‐mouth disease virus, a member of the Picornaviridae family, is a papain‐like cysteine protease that self‐cleaves from the polyprotein. Early in infection, the L protease cleaves the translation initiation factors eIF4GI and eIF4GII, inducing the shutdown of cap‐dependent translation. However, the cleavage sites on the viral polyprotein, eIF4GI, and eIF4GII differ in sequence, challenging the definition of a consensus site for L targets. Identification of Gemin5 and Daxx proteolytic products in infected cells unveiled a motif centered on the RKAR sequence. The RBP Gemin5 is a member of the survival of motor neurons complex, a ribosome interacting protein, and a translation downregulator. Likewise, the Fas‐ligand Daxx is a multifunctional adaptor that plays key roles in transcription control, apoptosis, and innate immune antiviral response. Remarkably, the cleavage site on the RNA helicases MDA5 and LGP2, two relevant immune sensors of the retinoic acid‐inducible gene‐I (RIG‐I)‐like receptors family, resembles the L target site of Gemin5 and Daxx, and similar cleavage sites have been reported in ISG15 and TBK1, two proteins involved in type I interferon response and signaling pathway, respectively. In this review we dissect the features of the L cleavage sites in essential RBPs, eventually helping in the discovery of novel L targets. This article is categorized under:RNA in Disease and Development > RNA in Disease Translation > Translation Regulation
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Affiliation(s)
- Margarita Saiz
- Department of Genome Dynamics and Function, Centro de Biologia Molecular Severo Ochoa, Madrid, Spain
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44
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The internal ribosome entry site of the Dengue virus mRNA is active when cap-dependent translation initiation is inhibited. J Virol 2021; 95:JVI.01998-20. [PMID: 33298544 PMCID: PMC8092825 DOI: 10.1128/jvi.01998-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Dengue virus (DENV) is an enveloped, positive-sense, single-stranded RNA virus belonging to the Flaviviridae family. Translation initiation of the DENV mRNA can occur following a cap-dependent or a cap-independent mechanism. Two non-mutually exclusive cap-independent mechanisms of translation initiation have been described for the DENV mRNA. The first corresponds to a 5'end-dependent internal ribosome entry site (IRES)-independent mechanism, while the second relies on IRES-dependent initiation. In this report, we study the recently discovered DENV IRES. Results show that the DENV IRES is functional in the rabbit reticulocyte (RRL) in vitro translation system. In accordance, the activity of DENV IRES was resistant to the cleavage of eIF4G by the Foot-and-mouth disease virus leader protease in RRL. In cells, the DENV IRES exhibited only a marginal activity under standard culture conditions. The DENV IRES showed weak activity in HEK 293T cells; however, the DENV IRES activity was significantly enhanced in HEK 293T cells expressing the Human rhinovirus 2A protease. These findings suggest that the DENV IRES enables viral protein synthesis under conditions that suppress canonical translation initiation.IMPORTANCE Dengue virus (DENV), the etiological agent of Dengue, a febrile and hemorrhagic disease, infects millions of people per year in tropical and subtropical countries. When infecting cells, DENV induces stress conditions known to inhibit canonical protein synthesis. Under these conditions, DENV mRNA thrives using non-canonical modes of translation initiation. In this study, we characterize the mechanism dependent upon an internal ribosome entry site (IRES). Herein, we describe the activity of the DENV IRES in vitro and cells. We show that in cells, DENV IRES enables the viral mRNA to translate under conditions that suppress canonical translation initiation.
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45
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Trainor BM, Ghosh A, Pestov DG, Hellen CUT, Shcherbik N. A translation enhancer element from black beetle virus engages yeast eIF4G1 to drive cap-independent translation initiation. Sci Rep 2021; 11:2461. [PMID: 33510277 PMCID: PMC7844027 DOI: 10.1038/s41598-021-82025-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 01/14/2021] [Indexed: 01/13/2023] Open
Abstract
Cap-independent translation initiation plays crucial roles in fine-tuning gene expression under global translation shutdown conditions. Translation of uncapped or de-capped transcripts can be stimulated by Cap-independent translation enhancer (CITE) elements, but the mechanisms of CITE-mediated translation initiation remain understudied. Here, we characterized a short 5ʹ-UTR RNA sequence from black beetle virus, BBV-seq. Mutational analysis indicates that the entire BBV-seq is required for efficient translation initiation, but this sequence does not operate as an IRES-type module. In yeast cell-free translation extracts, BBV-seq promoted efficient initiation on cap-free mRNA using a scanning mechanism. Moreover, BBV-seq can increase translation efficiency resulting from conventional cap-dependent translation initiation. Using genetic approaches, we found that BBV-seq exploits RNA-binding properties of eIF4G1 to promote initiation. Thus, BBV-seq constitutes a previously uncharacterized short, linear CITE that influences eIF4G1 to initiate 5′ end-dependent, cap-independent translation. These findings bring new insights into CITE-mediated translational control of gene expression.
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Affiliation(s)
- Brandon M Trainor
- Department of Cell Biology and Neuroscience, School of Osteopathic Medicine, Rowan University, 2 Medical Center Drive, Stratford, NJ, 08084, USA.,Graduate School of Biomedical Sciences, Rowan University, 42 E. Laurel Road, Suite 2200, Stratford, NJ, 08084, USA
| | - Arnab Ghosh
- Department of Cell Biology and Neuroscience, School of Osteopathic Medicine, Rowan University, 2 Medical Center Drive, Stratford, NJ, 08084, USA.,Center for Gene Regulation in Health and Disease, Cleveland State University, 2121 Euclid Ave, Cleveland, OH, 44115, USA
| | - Dimitri G Pestov
- Department of Cell Biology and Neuroscience, School of Osteopathic Medicine, Rowan University, 2 Medical Center Drive, Stratford, NJ, 08084, USA
| | - Christopher U T Hellen
- Department of Cell Biology, State University of New York Downstate Health Sciences University, 450 Clarkson Avenue MSC 44, Brooklyn, NY, 11203, USA
| | - Natalia Shcherbik
- Department of Cell Biology and Neuroscience, School of Osteopathic Medicine, Rowan University, 2 Medical Center Drive, Stratford, NJ, 08084, USA.
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46
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Reovirus and the Host Integrated Stress Response: On the Frontlines of the Battle to Survive. Viruses 2021; 13:v13020200. [PMID: 33525628 PMCID: PMC7910986 DOI: 10.3390/v13020200] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 01/22/2021] [Accepted: 01/26/2021] [Indexed: 12/17/2022] Open
Abstract
Cells are continually exposed to stressful events, which are overcome by the activation of a number of genetic pathways. The integrated stress response (ISR) is a large component of the overall cellular response to stress, which ultimately functions through the phosphorylation of the alpha subunit of eukaryotic initiation factor-2 (eIF2α) to inhibit the energy-taxing process of translation. This response is instrumental in the inhibition of viral infection and contributes to evolution in viruses. Mammalian orthoreovirus (MRV), an oncolytic virus that has shown promise in over 30 phase I–III clinical trials, has been shown to induce multiple arms within the ISR pathway, but it successfully evades, modulates, or subverts each cellular attempt to inhibit viral translation. MRV has not yet received Food and Drug Administration (FDA) approval for general use in the clinic; therefore, researchers continue to study virus interactions with host cells to identify circumstances where MRV effectiveness in tumor killing can be improved. In this review, we will discuss the ISR, MRV modulation of the ISR, and discuss ways in which MRV interaction with the ISR may increase the effectiveness of cancer therapeutics whose modes of action are altered by the ISR.
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Abaeva IS, Vicens Q, Bochler A, Soufari H, Simonetti A, Pestova TV, Hashem Y, Hellen CUT. The Halastavi árva Virus Intergenic Region IRES Promotes Translation by the Simplest Possible Initiation Mechanism. Cell Rep 2020; 33:108476. [PMID: 33296660 DOI: 10.1016/j.celrep.2020.108476] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 10/05/2020] [Accepted: 11/12/2020] [Indexed: 01/01/2023] Open
Abstract
Dicistrovirus intergenic region internal ribosomal entry sites (IGR IRESs) do not require initiator tRNA, an AUG codon, or initiation factors and jumpstart translation from the middle of the elongation cycle via formation of IRES/80S complexes resembling the pre-translocation state. eEF2 then translocates the [codon-anticodon]-mimicking pseudoknot I (PKI) from ribosomal A sites to P sites, bringing the first sense codon into the decoding center. Halastavi árva virus (HalV) contains an IGR that is related to previously described IGR IRESs but lacks domain 2, which enables these IRESs to bind to individual 40S ribosomal subunits. By using in vitro reconstitution and cryoelectron microscopy (cryo-EM), we now report that the HalV IGR IRES functions by the simplest initiation mechanism that involves binding to 80S ribosomes such that PKI is placed in the P site, so that the A site contains the first codon that is directly accessible for decoding without prior eEF2-mediated translocation of PKI.
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Affiliation(s)
- Irina S Abaeva
- Department of Cell Biology, SUNY Downstate Health Sciences University, 450 Clarkson Avenue, MSC 44, Brooklyn, NY 11203, USA
| | - Quentin Vicens
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, 15 rue René Descartes, 67000 Strasbourg, France
| | - Anthony Bochler
- INSERM U1212 Acides Nucléiques: Régulations Naturelle et Artificielle, Institut Européen de Chimie et Biologie, Université de Bordeaux, Pessac 33607, France; Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, 15 rue René Descartes, 67000 Strasbourg, France
| | - Heddy Soufari
- INSERM U1212 Acides Nucléiques: Régulations Naturelle et Artificielle, Institut Européen de Chimie et Biologie, Université de Bordeaux, Pessac 33607, France
| | - Angelita Simonetti
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, 15 rue René Descartes, 67000 Strasbourg, France
| | - Tatyana V Pestova
- Department of Cell Biology, SUNY Downstate Health Sciences University, 450 Clarkson Avenue, MSC 44, Brooklyn, NY 11203, USA.
| | - Yaser Hashem
- INSERM U1212 Acides Nucléiques: Régulations Naturelle et Artificielle, Institut Européen de Chimie et Biologie, Université de Bordeaux, Pessac 33607, France.
| | - Christopher U T Hellen
- Department of Cell Biology, SUNY Downstate Health Sciences University, 450 Clarkson Avenue, MSC 44, Brooklyn, NY 11203, USA.
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Despons L, Martin F. How Many Messenger RNAs Can Be Translated by the START Mechanism? Int J Mol Sci 2020; 21:ijms21218373. [PMID: 33171614 PMCID: PMC7664666 DOI: 10.3390/ijms21218373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/29/2020] [Accepted: 11/05/2020] [Indexed: 11/22/2022] Open
Abstract
Translation initiation is a key step in the protein synthesis stage of the gene expression pathway of all living cells. In this important process, ribosomes have to accurately find the AUG start codon in order to ensure the integrity of the proteome. “Structure Assisted RNA Translation”, or “START”, has been proposed to use stable secondary structures located in the coding sequence to augment start site selection by steric hindrance of the progression of pre-initiation complex on messenger RNA. This implies that such structures have to be located downstream and at on optimal distance from the AUG start codon (i.e., downstream nucleotide +16). In order to assess the importance of the START mechanism in the overall mRNA translation process, we developed a bioinformatic tool to screen coding sequences for such stable structures in a 50 nucleotide-long window spanning the nucleotides from +16 to +65. We screened eight bacterial genomes and six eukaryotic genomes. We found stable structures in 0.6–2.5% of eukaryotic coding sequences. Among these, approximately half of them were structures predicted to form G-quadruplex structures. In humans, we selected 747 structures. In bacteria, the coding sequences from Gram-positive bacteria contained 2.6–4.2% stable structures, whereas the structures were less abundant in Gram-negative bacteria (0.2–2.7%). In contrast to eukaryotes, putative G-quadruplex structures are very rare in the coding sequence of bacteria. Altogether, our study reveals that the START mechanism seems to be an ancient strategy to facilitate the start codon recognition that is used in different kingdoms of life.
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Athar YM, Joseph S. The Human Fragile X Mental Retardation Protein Inhibits the Elongation Step of Translation through Its RGG and C-Terminal Domains. Biochemistry 2020; 59:3813-3822. [PMID: 32945655 DOI: 10.1021/acs.biochem.0c00534] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The fragile X mental retardation protein (FMRP) is an RNA-binding protein that regulates the translation of numerous mRNAs in neurons. The precise mechanism of translational regulation by FMRP is unknown. Some studies have indicated that FMRP inhibits the initiation step of translation, whereas other studies have indicated that the elongation step of translation is inhibited by FMRP. To determine whether FMRP inhibits the initiation or the elongation step of protein synthesis, we investigated m7G-cap-dependent and IRES-driven, cap-independent translation of several reporter mRNAs in vitro. Our results show that FMRP inhibits both m7G-cap-dependent and cap-independent translation to similar degrees, indicating that the elongation step of translation is inhibited by FMRP. Additionally, we dissected the RNA-binding domains of hFMRP to determine the essential domains for inhibiting translation. We show that the RGG domain, together with the C-terminal domain (CTD), is sufficient to inhibit translation, while the KH domains do not inhibit mRNA translation. However, the region between the RGG domain and the KH2 domain may contribute as NT-hFMRP shows more potent inhibition than the RGG-CTD tail alone. Interestingly, we see a correlation between ribosome binding and translation inhibition, suggesting the RGG-CTD tail of hFMRP may anchor FMRP to the ribosome during translation inhibition.
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Affiliation(s)
- Youssi M Athar
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0314, United States
| | - Simpson Joseph
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0314, United States
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Beckham SA, Matak MY, Belousoff MJ, Venugopal H, Shah N, Vankadari N, Elmlund H, Nguyen JHC, Semler BL, Wilce MCJ, Wilce JA. Structure of the PCBP2/stem-loop IV complex underlying translation initiation mediated by the poliovirus type I IRES. Nucleic Acids Res 2020; 48:8006-8021. [PMID: 32556302 PMCID: PMC7641305 DOI: 10.1093/nar/gkaa519] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 05/15/2020] [Accepted: 06/06/2020] [Indexed: 02/02/2023] Open
Abstract
The poliovirus type I IRES is able to recruit ribosomal machinery only in the presence of host factor PCBP2 that binds to stem-loop IV of the IRES. When PCBP2 is cleaved in its linker region by viral proteinase 3CD, translation initiation ceases allowing the next stage of replication to commence. Here, we investigate the interaction of PCBP2 with the apical region of stem-loop IV (SLIVm) of poliovirus RNA in its full-length and truncated form. CryoEM structure reconstruction of the full-length PCBP2 in complex with SLIVm solved to 6.1 Å resolution reveals a compact globular complex of PCBP2 interacting with the cruciform RNA via KH domains and featuring a prominent GNRA tetraloop. SEC-SAXS, SHAPE and hydroxyl-radical cleavage establish that PCBP2 stabilizes the SLIVm structure, but upon cleavage in the linker domain the complex becomes more flexible and base accessible. Limited proteolysis and REMSA demonstrate the accessibility of the linker region in the PCBP2/SLIVm complex and consequent loss of affinity of PCBP2 for the SLIVm upon cleavage. Together this study sheds light on the structural features of the PCBP2/SLIV complex vital for ribosomal docking, and the way in which this key functional interaction is regulated following translation of the poliovirus genome.
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Affiliation(s)
- Simone A Beckham
- Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Mehdi Y Matak
- Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Matthew J Belousoff
- Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Hariprasad Venugopal
- The Ramaciotti Centre for Cryo-Electron Microscopy, Monash University, Victoria 3800, Australia
| | - Neelam Shah
- Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Naveen Vankadari
- Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Hans Elmlund
- Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Joseph H C Nguyen
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697-4025, USA
| | - Bert L Semler
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697-4025, USA
| | - Matthew C J Wilce
- Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Jacqueline A Wilce
- Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
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