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Ren X, Wang D, Zhang G, Zhou T, Wei Z, Yang Y, Zheng Y, Lei X, Tao W, Wang A, Li M, Flavell RA, Zhu S. Nucleic DHX9 cooperates with STAT1 to transcribe interferon-stimulated genes. SCIENCE ADVANCES 2023; 9:eadd5005. [PMID: 36735791 PMCID: PMC9897671 DOI: 10.1126/sciadv.add5005] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 01/05/2023] [Indexed: 06/13/2023]
Abstract
RNA helicase DHX9 has been extensively characterized as a transcriptional regulator, which is consistent with its mostly nucleic localization. It is also involved in recognizing RNA viruses in the cytoplasm. However, there is no in vivo data to support the antiviral role of DHX9; meanwhile, as a nuclear protein, if and how nucleic DHX9 promotes antiviral immunity remains largely unknown. Here, we generated myeloid-specific and hepatocyte-specific DHX9 knockout mice and confirmed that DHX9 is crucial for host resistance to RNA virus infections in vivo. By additional knockout MAVS or STAT1 in DHX9-deficient mice, we demonstrated that nucleic DHX9 plays a positive role in regulating interferon-stimulated gene (ISG) expression downstream of type I interferon. Mechanistically, upon interferon stimulation, DHX9 is directly bound to STAT1 and recruits Pol II to the ISG promoter region to participate in STAT1-mediated transcription of ISGs. Collectively, these findings uncover an important role for nucleic DHX9 in antiviral immunity.
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Affiliation(s)
- Xingxing Ren
- Department of Digestive Disease, Division of Life Sciences and Medicine, The First Affiliated Hospital of University of Science and Technology of China, University of Science and Technology of China, 230001 Hefei, China
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- Department of Gastroenterology, Third Affiliated Hospital of Guangzhou Medical University, 510145 Guangzhou, China
| | - Decai Wang
- Department of Digestive Disease, Division of Life Sciences and Medicine, The First Affiliated Hospital of University of Science and Technology of China, University of Science and Technology of China, 230001 Hefei, China
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Guorong Zhang
- Department of Digestive Disease, Division of Life Sciences and Medicine, The First Affiliated Hospital of University of Science and Technology of China, University of Science and Technology of China, 230001 Hefei, China
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Tingyue Zhou
- Department of Digestive Disease, Division of Life Sciences and Medicine, The First Affiliated Hospital of University of Science and Technology of China, University of Science and Technology of China, 230001 Hefei, China
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Zheng Wei
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, New Haven, CT 06510, USA
| | - Yi Yang
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, New Haven, CT 06510, USA
| | - Yunjiang Zheng
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, New Haven, CT 06510, USA
| | - Xuqiu Lei
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, New Haven, CT 06510, USA
| | - Wanyin Tao
- Department of Digestive Disease, Division of Life Sciences and Medicine, The First Affiliated Hospital of University of Science and Technology of China, University of Science and Technology of China, 230001 Hefei, China
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Anmin Wang
- Department of Digestive Disease, Division of Life Sciences and Medicine, The First Affiliated Hospital of University of Science and Technology of China, University of Science and Technology of China, 230001 Hefei, China
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Mingsong Li
- Department of Gastroenterology, Third Affiliated Hospital of Guangzhou Medical University, 510145 Guangzhou, China
| | - Richard A. Flavell
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, New Haven, CT 06510, USA
- Howard Hughes Medical Institute, Yale University School of Medicine, 300 Cedar Street, New Haven, CT 06510, USA
| | - Shu Zhu
- Department of Digestive Disease, Division of Life Sciences and Medicine, The First Affiliated Hospital of University of Science and Technology of China, University of Science and Technology of China, 230001 Hefei, China
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- School of Data Science, University of Science and Technology of China, Hefei 230026, China
- Institute of Health and Medicine, Hefei Comprehensive National Science Center, Hefei, China
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Mann JT, Riley BA, Baker SF. All differential on the splicing front: Host alternative splicing alters the landscape of virus-host conflict. Semin Cell Dev Biol 2023; 146:40-56. [PMID: 36737258 DOI: 10.1016/j.semcdb.2023.01.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/24/2023] [Accepted: 01/25/2023] [Indexed: 02/05/2023]
Abstract
Alternative RNA splicing is a co-transcriptional process that richly increases proteome diversity, and is dynamically regulated based on cell species, lineage, and activation state. Virus infection in vertebrate hosts results in rapid host transcriptome-wide changes, and regulation of alternative splicing can direct a combinatorial effect on the host transcriptome. There has been a recent increase in genome-wide studies evaluating host alternative splicing during viral infection, which integrates well with prior knowledge on viral interactions with host splicing proteins. A critical challenge remains in linking how these individual events direct global changes, and whether alternative splicing is an overall favorable pathway for fending off or supporting viral infection. Here, we introduce the process of alternative splicing, discuss how to analyze splice regulation, and detail studies on genome-wide and splice factor changes during viral infection. We seek to highlight where the field can focus on moving forward, and how incorporation of a virus-host co-evolutionary perspective can benefit this burgeoning subject.
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Affiliation(s)
- Joshua T Mann
- Infectious Disease Program, Lovelace Biomedical Research Institute, Albuquerque, NM, USA
| | - Brent A Riley
- Infectious Disease Program, Lovelace Biomedical Research Institute, Albuquerque, NM, USA
| | - Steven F Baker
- Infectious Disease Program, Lovelace Biomedical Research Institute, Albuquerque, NM, USA.
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eIF4A3 Promotes RNA Viruses’ Replication by Inhibiting Innate Immune Responses. J Virol 2022; 96:e0151322. [PMID: 36314820 PMCID: PMC9683021 DOI: 10.1128/jvi.01513-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Production of type I IFN is pivotal for the cellular antiviral immunity. Virus infection leads to the activation of transcription factor IRF3 and subsequent production of type I IFN to eliminate viral infection.
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4
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TREX (transcription/export)-NP complex exerts a dual effect on regulating polymerase activity and replication of influenza A virus. PLoS Pathog 2022; 18:e1010835. [PMID: 36084138 PMCID: PMC9491529 DOI: 10.1371/journal.ppat.1010835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 09/21/2022] [Accepted: 08/29/2022] [Indexed: 11/30/2022] Open
Abstract
Influenza A viruses effectively hijack the intracellular "resources" to complete transcription and replication, which involve extensive interactions between the viral and host proteins. Herein, we screened the host factors, which belong to DExD/H-box protein family members, RNA-binding proteins or mitochondrial anchoring proteins, to investigate their effects on polymerase activity. We observed DDX39B and DDX39A, DEAD-box RNA-Helicases, exert a dual effect on regulating polymerase activity and replication of influenza A viruses. We further revealed that DDX39B and DDX39A interact with viral NP and NS1 proteins. Interestingly, the viral NP proteins could reverse the inhibitory effect of excess DDX39B or DDX39A on polymerase activity. Mechanistically, the TREX complex subunits, THOC1, THOC4 and CIP29, were recruited to DDX39B-DDX39A-NP complex in an ATP-dependent manner, via the interaction with DDX39B or DDX39A, followed by excess TREX-NP complexes interfere with the normal oligomerization state of NP depending on the ratio between the viral and host proteins. On the other hand, the TREX complex, an evolutionarily conserved protein complex, is responsible for the integration of several mRNA processing steps to export viral mRNA. Knockdown of TREX complex subunits significantly down-regulated viral titers and protein levels, accompanied by retention of viral mRNA in the nucleus. Taken together, screening the host factors that regulate the replication of influenza virus advances our understanding of viral pathogenesis and our findings point out a previously unclear mechanism of TREX complex function. In this study, we investigated the regulation of polymerase activity by host factors associated with vRNPs (PB2627E, PB2627K, PB2627 domain del, PB2627 CON) and provided novel insights into regulatory mechanisms of DDX39B and DDX39A during viral replication. Our results demonstrated that DDX39B and its paralog DDX39A inhibited polymerase activity via forming TREX-NP complex with concomitant effects on the oligomeric state of NP proteins. Moreover, TREX complex is necessary for expression of viral proteins. Our findings provided potential therapeutic targets for dealing with IAV infection.
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Lao G, Ma K, Qiu Z, Qi W, Liao M, Li H. Real-Time Visualization of the Infection and Replication of a Mouse-Lethal Recombinant H9N2 Avian Influenza Virus. Front Vet Sci 2022; 9:849178. [PMID: 35280146 PMCID: PMC8907971 DOI: 10.3389/fvets.2022.849178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 01/31/2022] [Indexed: 11/25/2022] Open
Abstract
H9N2 avian influenza viruses (AIVs) continuously cross the species barrier to infect mammalians and are repeatedly transmitted to humans, posing a significant threat to public health. Importantly, some H9N2 AIVs were found to cause lethal infection in mice, but little is known about the viral infection dynamics in vivo. To analyze the real-time infection dynamics, we described the generation of a mouse-lethal recombinant H9N2 AIV, an influenza reporter virus (VK627-NanoLuc virus) carrying a NanoLuc gene in the non-structural (NS) segment, which was available for in vivo imaging. Although attenuated for replication in MDCK cells, VK627-NanoLuc virus showed similar pathogenicity and replicative capacity in mice to its parental virus. Bioluminescent imaging of the VK627-NanoLuc virus permitted successive observations of viral infection and replication in infected mice, even following the viral clearance of a sublethal infection. Moreover, VK627-NanoLuc virus was severely restricted by the K627E mutation in PB2, as infected mice showed little weight loss and a low level of bioluminescence. In summary, we have preliminarily established a visualized tool that enables real-time observation of the infection and replication dynamics of H9N2 AIV in mice, which contributes to further understanding the mechanisms underlying the pathogenic enhancement of H9N2 AIV to mice.
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Affiliation(s)
- Guangjie Lao
- National Avian Influenza Para-Reference Laboratory (Guangzhou), South China Agricultural University, Guangzhou, China
- Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou, China
| | - Kaixiong Ma
- National Avian Influenza Para-Reference Laboratory (Guangzhou), South China Agricultural University, Guangzhou, China
- Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou, China
| | - Ziwen Qiu
- National Avian Influenza Para-Reference Laboratory (Guangzhou), South China Agricultural University, Guangzhou, China
- Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou, China
| | - Wenbao Qi
- National Avian Influenza Para-Reference Laboratory (Guangzhou), South China Agricultural University, Guangzhou, China
- Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou, China
- National and Regional Joint Engineering Laboratory for Medicament of Zoonoses Prevention and Control, Guangzhou, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou, China
| | - Ming Liao
- National Avian Influenza Para-Reference Laboratory (Guangzhou), South China Agricultural University, Guangzhou, China
- Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou, China
- National and Regional Joint Engineering Laboratory for Medicament of Zoonoses Prevention and Control, Guangzhou, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou, China
- *Correspondence: Ming Liao
| | - Huanan Li
- National Avian Influenza Para-Reference Laboratory (Guangzhou), South China Agricultural University, Guangzhou, China
- Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou, China
- National and Regional Joint Engineering Laboratory for Medicament of Zoonoses Prevention and Control, Guangzhou, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou, China
- Huanan Li
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6
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Xing J, Liang J, Liu S, Huang L, Hu P, Liu L, Liao M, Qi W. Japanese encephalitis virus restricts HMGB1 expression to maintain MAPK pathway activation for viral replication. Vet Microbiol 2021; 262:109237. [PMID: 34592637 DOI: 10.1016/j.vetmic.2021.109237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 09/11/2021] [Indexed: 12/17/2022]
Abstract
Japanese encephalitis virus (JEV) is a typical insect-borne flavivirus and an important zoonotic pathogen that causes human viral encephalitis and reproductive failure in pigs. Various strategies were utilized by JEV to facilitate its replication. It is important to identify key molecules that mediate JEV infection, as well as to investigate their underlying mechanism. In this study, the critical role of high-mobility group box 1 (HMGB1), a non-histone, DNA-binding protein, was assessed in JEV propagation. Upon JEV infection, the HMGB1 mRNA and protein levels were down-regulated at late infection in Huh7 cells. JEV replication was significantly enhanced with HMGB1 knock-down by siRNA and knock-out by the CRISPR/Cas9 system, whereas JEV growth was restricted in HMGB1-over-expressed Huh7 cells. Further investigation showed that HMGB1 suppressed MAPK pathway, and demonstrated that the weakening of MAPK pathway negatively regulated JEV infection. Together, these results suggested that JEV restricted HMGB1 expression to maintain MAPK pathway activation for viral replication. Our data showed that HMGB1 played a key role in JEV infection, providing the potential for the development of a novel drug to combat JEV infection.
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Affiliation(s)
- Jinchao Xing
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou 510642, China; Key Laboratory of Zoonoses Prevention and Control of Guangdong Province, Guangzhou 510642, China
| | - Jiaqi Liang
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou 510642, China; Key Laboratory of Zoonoses Prevention and Control of Guangdong Province, Guangzhou 510642, China
| | - Shukai Liu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
| | - Lihong Huang
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong 999077, China
| | - Pingsheng Hu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
| | - Lele Liu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou 510642, China; Key Laboratory of Zoonoses Prevention and Control of Guangdong Province, Guangzhou 510642, China
| | - Ming Liao
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China; Key Laboratory of Zoonoses Prevention and Control of Guangdong Province, Guangzhou 510642, China.
| | - Wenbao Qi
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China; National Engineering Research Center for Breeding Swine Industry, Guangzhou 510642, China; Key Laboratory of Zoonoses Prevention and Control of Guangdong Province, Guangzhou 510642, China.
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7
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Froggatt HM, Burke KN, Chaparian RR, Miranda HA, Zhu X, Chambers BS, Heaton NS. Influenza A virus segments five and six can harbor artificial introns allowing expanded coding capacity. PLoS Pathog 2021; 17:e1009951. [PMID: 34570829 PMCID: PMC8496794 DOI: 10.1371/journal.ppat.1009951] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 10/07/2021] [Accepted: 09/08/2021] [Indexed: 12/30/2022] Open
Abstract
Influenza A viruses encode their genomes across eight, negative sense RNA segments. The six largest segments produce mRNA transcripts that do not generally splice; however, the two smallest segments are actively spliced to produce the essential viral proteins NEP and M2. Thus, viral utilization of RNA splicing effectively expands the viral coding capacity without increasing the number of genomic segments. As a first step towards understanding why splicing is not more broadly utilized across genomic segments, we designed and inserted an artificial intron into the normally nonsplicing NA segment. This insertion was tolerated and, although viral mRNAs were incompletely spliced, we observed only minor effects on viral fitness. To take advantage of the unspliced viral RNAs, we encoded a reporter luciferase gene in frame with the viral ORF such that when the intron was not removed the reporter protein would be produced. This approach, which we also show can be applied to the NP encoding segment and in different viral genetic backgrounds, led to high levels of reporter protein expression with minimal effects on the kinetics of viral replication or the ability to cause disease in experimentally infected animals. These data together show that the influenza viral genome is more tolerant of splicing than previously appreciated and this knowledge can be leveraged to develop viral genetic platforms with utility for biotechnology applications. Unlike most host mRNAs, some viral mRNAs encode multiple discrete, functional proteins. One method influenza A viruses use to increase the protein products from two of their eight RNA genome segments is splicing. Splicing requires host machinery to remove part of the viral mRNA, the intron, to generate a different mRNA product. Although only certain influenza viral segments naturally splice, we were interested in whether additional segments could splice to produce multiple proteins. We inserted artificial introns harboring reporter genes into otherwise nonsplicing genomic segments of an H1N1 influenza A virus and found that this modification was well tolerated by the virus. We further demonstrated that an unrelated H3N2 influenza A virus could similarly support splicing and express a reporter protein from an artificial intron. These findings have implications for our understanding of how viruses expand their coding capacity with a limited genome. Additionally, encoding reporter proteins in spliced intronic sequences also represents a new method of generating reporter viruses requiring limited manipulation of the viral RNA.
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Affiliation(s)
- Heather M. Froggatt
- Department of Molecular Genetics and Microbiology Duke University School of Medicine Durham, North Carolina, United States of America
| | - Kaitlyn N. Burke
- Department of Molecular Genetics and Microbiology Duke University School of Medicine Durham, North Carolina, United States of America
| | - Ryan R. Chaparian
- Department of Molecular Genetics and Microbiology Duke University School of Medicine Durham, North Carolina, United States of America
| | - Hector A. Miranda
- Department of Molecular Genetics and Microbiology Duke University School of Medicine Durham, North Carolina, United States of America
| | - Xinyu Zhu
- Department of Molecular Genetics and Microbiology Duke University School of Medicine Durham, North Carolina, United States of America
| | - Benjamin S. Chambers
- Department of Molecular Genetics and Microbiology Duke University School of Medicine Durham, North Carolina, United States of America
| | - Nicholas S. Heaton
- Department of Molecular Genetics and Microbiology Duke University School of Medicine Durham, North Carolina, United States of America
- Duke Human Vaccine Institute Duke University School of Medicine Durham, North Carolina, United States of America
- * E-mail:
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8
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Cellular hnRNPAB interacts with avian influenza viral protein PB2 and inhibits virus replication potentially by restricting PB2 mRNA nuclear export and PB2 protein level. Virus Res 2021; 305:198573. [PMID: 34555436 DOI: 10.1016/j.virusres.2021.198573] [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: 04/27/2021] [Revised: 09/07/2021] [Accepted: 09/09/2021] [Indexed: 11/24/2022]
Abstract
The PB2 protein of avian influenza virus (AIV) is essential for transcription and replication of virus genome. In this study, we reported that chicken heterogenous nuclear riboncleoprotein AB (hnRNPAB) cooperated with avian influenza viral protein PB2 and inhibited the polymerase activity and virus replication. We found that hnRNPAB was associated with PB2 mRNA and overexpression of hnRNPAB reduced PB2 mRNA nuclear export and PB2 protein level, but had no influence on PB2 mRNA level. At the same time, overexpression of hnRNPAB also reduced protein levels rather than mRNA levels of PA, PB1 and NP. In addition, overexpression of hnRNPAB restricted the polymerase activity and virus replication, while knockdown of hnRNPAB resulted in enhanced polymerase activity and virus replication. Lastly, virus infection induced the nuclear accumulation of hnRNPAB, but did not cause the change of expression level of endogenous hnRNPAB in DF-1 cells. Collectively, these findings suggested that hnRNPAB played a restrictive role in polymerase activity and virus replication potentially through inhibiting PB2 mRNA nuclear export and PB2 protein level.
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Kubina J, Geldreich A, Gales JP, Baumberger N, Bouton C, Ryabova LA, Grasser KD, Keller M, Dimitrova M. Nuclear export of plant pararetrovirus mRNAs involves the TREX complex, two viral proteins and the highly structured 5' leader region. Nucleic Acids Res 2021; 49:8900-8922. [PMID: 34370034 PMCID: PMC8421220 DOI: 10.1093/nar/gkab653] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 07/09/2021] [Accepted: 07/22/2021] [Indexed: 11/13/2022] Open
Abstract
In eukaryotes, the major nuclear export pathway for mature mRNAs uses the dimeric receptor TAP/p15, which is recruited to mRNAs via the multisubunit TREX complex, comprising the THO core and different export adaptors. Viruses that replicate in the nucleus adopt different strategies to hijack cellular export factors and achieve cytoplasmic translation of their mRNAs. No export receptors are known in plants, but Arabidopsis TREX resembles the mammalian complex, with a conserved hexameric THO core associated with ALY and UIEF proteins, as well as UAP56 and MOS11. The latter protein is an orthologue of mammalian CIP29. The nuclear export mechanism for viral mRNAs has not been described in plants. To understand this process, we investigated the export of mRNAs of the pararetrovirus CaMV in Arabidopsis and demonstrated that it is inhibited in plants deficient in ALY, MOS11 and/or TEX1. Deficiency for these factors renders plants partially resistant to CaMV infection. Two CaMV proteins, the coat protein P4 and reverse transcriptase P5, are important for nuclear export. P4 and P5 interact and co-localise in the nucleus with the cellular export factor MOS11. The highly structured 5′ leader region of 35S RNAs was identified as an export enhancing element that interacts with ALY1, ALY3 and MOS11 in vitro.
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Affiliation(s)
- Julie Kubina
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Angèle Geldreich
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Jón Pol Gales
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Nicolas Baumberger
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Clément Bouton
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Lyubov A Ryabova
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Klaus D Grasser
- Cell Biology & Plant Biochemistry, Biochemistry Centre, University of Regensburg, D-93053 Regensburg, Germany
| | - Mario Keller
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Maria Dimitrova
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
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10
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Host factors involved in influenza virus infection. Emerg Top Life Sci 2020; 4:389-398. [PMID: 33210707 DOI: 10.1042/etls20200232] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/14/2020] [Accepted: 10/30/2020] [Indexed: 12/17/2022]
Abstract
Influenza virus causes an acute febrile respiratory disease in humans that is commonly known as 'flu'. Influenza virus has been around for centuries and is one of the most successful, and consequently most studied human viruses. This has generated tremendous amount of data and information, thus it is pertinent to summarise these for, particularly interdisciplinary readers. Viruses are acellular organisms and exist at the interface of living and non-living. Due to this unique characteristic, viruses require another organism, i.e. host to survive. Viruses multiply inside the host cell and are obligate intracellular pathogens, because their relationship with the host is almost always harmful to host. In mammalian cells, the life cycle of a virus, including influenza is divided into five main steps: attachment, entry, synthesis, assembly and release. To complete these steps, some viruses, e.g. influenza utilise all three parts - plasma membrane, cytoplasm and nucleus, of the cell; whereas others, e.g. SARS-CoV-2 utilise only plasma membrane and cytoplasm. Hence, viruses interact with numerous host factors to complete their life cycle, and these interactions are either exploitative or antagonistic in nature. The host factors involved in the life cycle of a virus could be divided in two broad categories - proviral and antiviral. This perspective has endeavoured to assimilate the information about the host factors which promote and suppress influenza virus infection. Furthermore, an insight into host factors that play a dual role during infection or contribute to influenza virus-host adaptation and disease severity has also been provided.
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11
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Gales JP, Kubina J, Geldreich A, Dimitrova M. Strength in Diversity: Nuclear Export of Viral RNAs. Viruses 2020; 12:E1014. [PMID: 32932882 PMCID: PMC7551171 DOI: 10.3390/v12091014] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/03/2020] [Accepted: 09/09/2020] [Indexed: 12/11/2022] Open
Abstract
The nuclear export of cellular mRNAs is a complex process that requires the orchestrated participation of many proteins that are recruited during the early steps of mRNA synthesis and processing. This strategy allows the cell to guarantee the conformity of the messengers accessing the cytoplasm and the translation machinery. Most transcripts are exported by the exportin dimer Nuclear RNA export factor 1 (NXF1)-NTF2-related export protein 1 (NXT1) and the transcription-export complex 1 (TREX1). Some mRNAs that do not possess all the common messenger characteristics use either variants of the NXF1-NXT1 pathway or CRM1, a different exportin. Viruses whose mRNAs are synthesized in the nucleus (retroviruses, the vast majority of DNA viruses, and influenza viruses) exploit both these cellular export pathways. Viral mRNAs hijack the cellular export machinery via complex secondary structures recognized by cellular export factors and/or viral adapter proteins. This way, the viral transcripts succeed in escaping the host surveillance system and are efficiently exported for translation, allowing the infectious cycle to proceed. This review gives an overview of the cellular mRNA nuclear export mechanisms and presents detailed insights into the most important strategies that viruses use to export the different forms of their RNAs from the nucleus to the cytoplasm.
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Affiliation(s)
- Jón Pol Gales
- Institut de Biologie Moléculaire des Plantes, The French National Center for Scientific Research (CNRS) UPR2357, Université de Strasbourg, F-67084 Strasbourg, France; (J.P.G.); (J.K.); (A.G.)
| | - Julie Kubina
- Institut de Biologie Moléculaire des Plantes, The French National Center for Scientific Research (CNRS) UPR2357, Université de Strasbourg, F-67084 Strasbourg, France; (J.P.G.); (J.K.); (A.G.)
- SVQV UMR-A 1131, INRAE, Université de Strasbourg, F-68000 Colmar, France
| | - Angèle Geldreich
- Institut de Biologie Moléculaire des Plantes, The French National Center for Scientific Research (CNRS) UPR2357, Université de Strasbourg, F-67084 Strasbourg, France; (J.P.G.); (J.K.); (A.G.)
| | - Maria Dimitrova
- Institut de Biologie Moléculaire des Plantes, The French National Center for Scientific Research (CNRS) UPR2357, Université de Strasbourg, F-67084 Strasbourg, France; (J.P.G.); (J.K.); (A.G.)
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Nilsson K, Abdurahman S, Schwartz S. Influenza virus natural sequence heterogeneity in segment 8 affects interactions with cellular RNA-binding proteins and splicing efficiency. Virology 2020; 549:39-50. [PMID: 32829114 DOI: 10.1016/j.virol.2020.08.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 08/11/2020] [Accepted: 08/12/2020] [Indexed: 11/18/2022]
Abstract
Segment 8 mRNAs of influenza virus A/Brevig Misson/1918/1 (H1N1) are poorly spliced compared to segment 8 mRNAs of influenza virus A/Netherlands/178/95 (H3N2). Using oligonucleotide-mediated protein pull down with oligos spanning the entire length of segment 8 of either influenza virus H1N1 or influenza virus H3N2 we identified cellular RNA binding proteins that interacted with oligonucleotides derived from either H1N1 or H3N2 sequences. When the identified hot spots for RNA binding proteins in H1N1 segment 8 mRNAs were replaced by H3N2 sequences, splicing efficiency increased significantly. Replacing as few as three nucleotides of the H1N1 mRNA with sequences from H3N2 mRNA, enhanced splicing of the H1N1 mRNAs. Cellular proteins U2AF65 and HuR interacted preferentially with the 3'-splice site of H3N2 and overexpression of HuR reduced the levels of unspliced H1N1 mRNAs, suggesting that U2AF65 and HuR contribute to control of influenza virus mRNA splicing.
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MESH Headings
- A549 Cells
- Alternative Splicing
- ELAV-Like Protein 1/genetics
- ELAV-Like Protein 1/metabolism
- Genetic Variation
- HeLa Cells
- Host-Pathogen Interactions/genetics
- Humans
- Influenza A Virus, H1N1 Subtype/genetics
- Influenza A Virus, H1N1 Subtype/metabolism
- Influenza A Virus, H3N2 Subtype/genetics
- Influenza A Virus, H3N2 Subtype/metabolism
- Oligonucleotides/chemistry
- Oligonucleotides/metabolism
- Plasmids/chemistry
- Plasmids/metabolism
- Protein Binding
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Viral/chemistry
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Splicing Factor U2AF/genetics
- Splicing Factor U2AF/metabolism
- Transfection
- Viral Nonstructural Proteins/genetics
- Viral Nonstructural Proteins/metabolism
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Affiliation(s)
- Kersti Nilsson
- Department of Laboratory Medicine, BMC-B13, Lund University, 221 84, Lund, Sweden
| | - Samir Abdurahman
- Department of Science and Technology, Örebro University, 701 82, Örebro, Sweden
| | - Stefan Schwartz
- Department of Laboratory Medicine, BMC-B13, Lund University, 221 84, Lund, Sweden.
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