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Sberna G, Maggi F, Amendola A. Virus-Encoded Circular RNAs: Role and Significance in Viral Infections. Int J Mol Sci 2023; 24:16547. [PMID: 38003737 PMCID: PMC10671809 DOI: 10.3390/ijms242216547] [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: 10/31/2023] [Revised: 11/17/2023] [Accepted: 11/19/2023] [Indexed: 11/26/2023] Open
Abstract
Circular RNAs (circRNAs) have been the focus of intense scientific research to understand their biogenesis, mechanisms of action and regulatory functions. CircRNAs are single stranded, covalently closed RNA molecules lacking the 5'-terminal cap and the 3'-terminal polyadenine chain, characteristics that make them very stable and resistant. Synthesised by both cells and viruses, in the past circRNAs were considered to have no precise function. Today, increasing evidence shows that circRNAs are ubiquitous, some of them are tissue- and cell-specific, and critical in multiple regulatory processes (i.e., infections, inflammation, oncogenesis, gene expression). Moreover, circRNAs are emerging as important biomarkers of viral infection and disease progression. In this review, we provided an updated overview of current understanding of virus-encoded and cellular-encoded circRNAs and their involvement in cellular pathways during viral infection.
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Affiliation(s)
| | | | - Alessandra Amendola
- Laboratory of Virology and Biosafety Laboratories, National Institute for Infectious Diseases “L. Spallanzani” IRCCS, 00149 Rome, Italy; (G.S.)
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Bai Y, Liu D, He Q, Liu J, Mao Q, Liang Z. Research progress on circular RNA vaccines. Front Immunol 2023; 13:1091797. [PMID: 36713460 PMCID: PMC9878156 DOI: 10.3389/fimmu.2022.1091797] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 12/27/2022] [Indexed: 01/13/2023] Open
Abstract
Owing to the success of linear mRNA coronavirus disease 2019 (COVID-19) vaccines, biopharmaceutical companies and research teams worldwide have attempted to develop more stable circular RNA (circRNA) vaccines and have achieved some preliminary results. This review aims to summarize key findings and important progress made in circRNA research, the in vivo metabolism and biological functions of circRNAs, and research progress and production process of circRNA vaccines. Further, considerations regarding the quality control of circRNA vaccines are highlighted herein, and the main challenges and problem-solving strategies in circRNA vaccine development and quality control are outlined to provide a reference for circRNA vaccine-related research.
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Affiliation(s)
- Yu Bai
- Division of Hepatitis and Enterovirus Vaccines, National Institutes for Food and Drug Control, Beijing, China,NHC Key Laboratory of Research on Quality and Standardization of Biotech Products, National Institutes for Food and Drug Control, Beijing, China,NMPA Key Laboratory for Quality Research and Evaluation of Biological Products, Institute of Biological Products, National Institutes for Food and Drug Control, Beijing, China
| | - Dong Liu
- Division of Hepatitis and Enterovirus Vaccines, National Institutes for Food and Drug Control, Beijing, China,NHC Key Laboratory of Research on Quality and Standardization of Biotech Products, National Institutes for Food and Drug Control, Beijing, China,NMPA Key Laboratory for Quality Research and Evaluation of Biological Products, Institute of Biological Products, National Institutes for Food and Drug Control, Beijing, China
| | - Qian He
- Division of Hepatitis and Enterovirus Vaccines, National Institutes for Food and Drug Control, Beijing, China,NHC Key Laboratory of Research on Quality and Standardization of Biotech Products, National Institutes for Food and Drug Control, Beijing, China,NMPA Key Laboratory for Quality Research and Evaluation of Biological Products, Institute of Biological Products, National Institutes for Food and Drug Control, Beijing, China
| | - Jianyang Liu
- Division of Hepatitis and Enterovirus Vaccines, National Institutes for Food and Drug Control, Beijing, China,NHC Key Laboratory of Research on Quality and Standardization of Biotech Products, National Institutes for Food and Drug Control, Beijing, China,NMPA Key Laboratory for Quality Research and Evaluation of Biological Products, Institute of Biological Products, National Institutes for Food and Drug Control, Beijing, China
| | - Qunying Mao
- Division of Hepatitis and Enterovirus Vaccines, National Institutes for Food and Drug Control, Beijing, China,NHC Key Laboratory of Research on Quality and Standardization of Biotech Products, National Institutes for Food and Drug Control, Beijing, China,NMPA Key Laboratory for Quality Research and Evaluation of Biological Products, Institute of Biological Products, National Institutes for Food and Drug Control, Beijing, China,*Correspondence: Zhenglun Liang, ; Qunying Mao,
| | - Zhenglun Liang
- Division of Hepatitis and Enterovirus Vaccines, National Institutes for Food and Drug Control, Beijing, China,NHC Key Laboratory of Research on Quality and Standardization of Biotech Products, National Institutes for Food and Drug Control, Beijing, China,NMPA Key Laboratory for Quality Research and Evaluation of Biological Products, Institute of Biological Products, National Institutes for Food and Drug Control, Beijing, China,*Correspondence: Zhenglun Liang, ; Qunying Mao,
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Abstract
Circular RNAs (circRNAs) are a recently rediscovered class of functional noncoding RNAs that are involved in gene regulation and cancer development. Next-generation sequencing approaches identified circRNA fragments and sequences underlying circularization events in virus-induced cancers. In the present study, we performed viral circRNA expression analysis and full-length sequencing in infections with Marek’s disease virus (MDV), which serves as a model for herpesvirus-induced tumorigenesis. We established inverse PCRs to identify and characterize circRNA expression from the repeat regions of the MDV genome during viral replication, latency, and reactivation. We identified a large variety of viral circRNAs through precise mapping of full-length circular transcripts and detected matching sequences with several viral genes. Hot spots of circRNA expression included the transcriptional unit of the major viral oncogene encoding the Meq protein and the latency-associated transcripts (LATs). Moreover, we performed genome-wide bioinformatic analyses to extract back-splice junctions from lymphoma-derived samples. Using this strategy, we found that circRNAs were abundantly expressed in vivo from the same key virulence genes. Strikingly, the observed back-splice junctions do not follow a unique canonical pattern, compatible with the U2-dependent splicing machinery. Numerous noncanonical junctions were observed in viral circRNA sequences characterized from in vitro and in vivo infections. Given the importance of the genes involved in the transcription of these circRNAs, our study contributes to our understanding and complexity of this deadly pathogen. IMPORTANCE Circular RNAs (circRNAs) were rediscovered in recent years both in physiological and pathological contexts, such as in cancer. Viral circRNAs are encoded by at least two human herpesviruses, the Epstein Barr virus and the Kaposi’s Sarcoma-associated herpesvirus, both associated with the development of lymphoma. Marek’s disease virus (MDV) is a well-established animal model to study virus-induced lymphoma but circRNA expression has not been reported for MDV yet. Our study provided the first evidence of viral circRNAs that were expressed at key steps of the MDV lifecycle using genome-wide analyses of circRNAs. These circRNAs were primarily found in transcriptional units that corresponded to the major MDV virulence factors. In addition, we established a bioinformatics pipeline that offers a new tool to identify circular RNAs in other herpesviruses. This study on the circRNAs provided important insights into major MDV virulence genes and herpesviruses-mediated gene dysregulation.
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Harper KL, Mottram TJ, Anene CA, Foster B, Patterson MR, McDonnell E, Macdonald A, Westhead D, Whitehouse A. Dysregulation of the miR‐30c/DLL4 axis by circHIPK3 is essential for KSHV lytic replication. EMBO Rep 2022; 23:e54117. [PMID: 35239998 PMCID: PMC9066072 DOI: 10.15252/embr.202154117] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 02/15/2022] [Accepted: 02/18/2022] [Indexed: 11/09/2022] Open
Affiliation(s)
- Katherine L Harper
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology University of Leeds Leeds UK
| | - Timothy J Mottram
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology University of Leeds Leeds UK
| | - Chinedu A Anene
- Centre for Cancer Genomics and Computational Biology Barts Cancer Institute Queen Mary University of London London UK
| | - Becky Foster
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology University of Leeds Leeds UK
| | - Molly R Patterson
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology University of Leeds Leeds UK
| | - Euan McDonnell
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology University of Leeds Leeds UK
| | - Andrew Macdonald
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology University of Leeds Leeds UK
| | - David Westhead
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology University of Leeds Leeds UK
| | - Adrian Whitehouse
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology University of Leeds Leeds UK
- Department of Biochemistry and Microbiology Rhodes University Grahamstown South Africa
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5
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Chen LL, Wilusz JE. Methods for circular RNAs. Methods 2021; 196:1-2. [PMID: 34601050 DOI: 10.1016/j.ymeth.2021.09.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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6
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Yang R, Wang RC. Research Techniques Made Simple: Studying Circular RNA in Skin Diseases. J Invest Dermatol 2021; 141:2313-2319.e1. [PMID: 34560913 PMCID: PMC8480520 DOI: 10.1016/j.jid.2021.07.156] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 07/16/2021] [Accepted: 07/19/2021] [Indexed: 12/13/2022]
Abstract
Circular RNAs (circRNAs) are a unique class of covalently closed, single-stranded RNAs. High-throughput sequencing has uncovered the abundance and complexity of circRNAs. Changes in levels of circRNAs correlate with diverse disease states, including many skin diseases. CircRNAs can function as microRNA inhibitors, protein interactors, or mRNAs. Although circRNAs do have unique topological features, they share many similarities, including primary sequence, with their linear orthologs, so carefully controlled experiments are required to detect and study them. Here, we summarize some protocols used in the identification, validation, and characterization of circRNAs. We also discuss ways to repress and overexpress specific circRNAs to assess potential unique functions for these molecules. These techniques may be useful in exploring how circRNAs contribute to skin disease.
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Affiliation(s)
- Rong Yang
- Department of Dermatology, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Richard C Wang
- Department of Dermatology, The University of Texas Southwestern Medical Center, Dallas, Texas, USA; Harold C. Simmons Comprehensive Cancer Center, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
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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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Tagawa T, Oh D, Santos J, Dremel S, Mahesh G, Uldrick TS, Yarchoan R, Kopardé VN, Ziegelbauer JM. Characterizing Expression and Regulation of Gamma-Herpesviral Circular RNAs. Front Microbiol 2021; 12:670542. [PMID: 34276603 PMCID: PMC8278476 DOI: 10.3389/fmicb.2021.670542] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 06/08/2021] [Indexed: 12/18/2022] Open
Abstract
Multiple herpesviruses have been recently found to encode viral circular RNAs. Like cellular circular RNAs, these RNAs lack poly-A tails and their 5' and 3' ends have been joined, which confers protection from RNA exonucleases. We examined the expression patterns of circular RNAs from Kaposi's sarcoma herpesvirus (KSHV) in various environments. We performed deep sequencing of circRNA-enriched total RNA from a KSHV-positive patient lymph node for comparison with previous circRNA-Seq results. We found that circvIRF4 is highly expressed in the KSHV-positive patient sample relative to both B cell lines and de novo infected primary vascular and lymphatic endothelial cells (LECs). Overall, this patient sample showed a viral circRNA expression pattern more similar to the pattern from B cell lines, but we also discovered new back-spliced junctions and additional viral circular RNAs in this patient sample. We validated some of these back-spliced junctions as circular RNAs with standard assays. Differential expression patterns of circular RNAs in different cell types led us to investigate what cellular factors might be influencing the ratio of viral linear mRNAs to circular RNAs. We found that repression of certain RNA-binding proteins shifted the balance between viral linear mRNAs and circular RNAs. Taken together, examining viral circular RNA expression patterns may become useful tools for discovering their functions, the regulators of their expression, and determining the stage and cell types of infection in humans.
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Affiliation(s)
- Takanobu Tagawa
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, MD, United States
| | - Daniel Oh
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, MD, United States
| | - Jerico Santos
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, MD, United States
- Biological Models Laboratory, Department of Biochemistry and Molecular Biology, College of Medicine, University of the Philippines, Manila, Philippines
| | - Sarah Dremel
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, MD, United States
| | - Guruswamy Mahesh
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, MD, United States
| | - Thomas S. Uldrick
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, MD, United States
| | - Robert Yarchoan
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, MD, United States
| | - Vishal N. Kopardé
- CCR Collaborative Bioinformatics Resource, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
- Advanced Biomedical Computational Sciences, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD, United States
| | - Joseph M. Ziegelbauer
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, MD, United States
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