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Yerlici VT, Astori A, Kejiou NS, Jordan CA, Khosraviani N, Chan JNY, Hakem R, Raught B, Palazzo AF, Mekhail K. SARS-CoV-2 targets ribosomal RNA biogenesis. Cell Rep 2024; 43:113891. [PMID: 38427561 DOI: 10.1016/j.celrep.2024.113891] [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: 11/10/2022] [Revised: 10/02/2023] [Accepted: 02/15/2024] [Indexed: 03/03/2024] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) hinders host gene expression, curbing defenses and licensing viral protein synthesis and virulence. During SARS-CoV-2 infection, the virulence factor non-structural protein 1 (Nsp1) targets the mRNA entry channel of mature cytoplasmic ribosomes, limiting translation. We show that Nsp1 also restrains translation by targeting nucleolar ribosome biogenesis. SARS-CoV-2 infection disrupts 18S and 28S ribosomal RNA (rRNA) processing. Expression of Nsp1 recapitulates the processing defects. Nsp1 abrogates rRNA production without altering the expression of critical processing factors or nucleolar organization. Instead, Nsp1 localizes to the nucleolus, interacting with precursor-rRNA and hindering its maturation separately from the viral protein's role in restricting mature ribosomes. Thus, SARS-CoV-2 Nsp1 limits translation by targeting ribosome biogenesis and mature ribosomes. These findings revise our understanding of how SARS-CoV-2 Nsp1 controls human protein synthesis, suggesting that efforts to counter Nsp1's effect on translation should consider the protein's impact from ribosome manufacturing to mature ribosomes.
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Affiliation(s)
- V Talya Yerlici
- Department of Laboratory Medicine and Pathobiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Audrey Astori
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 1L7, Canada
| | - Nevraj S Kejiou
- Department of Biochemistry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Chris A Jordan
- Department of Laboratory Medicine and Pathobiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Negin Khosraviani
- Department of Laboratory Medicine and Pathobiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Janet N Y Chan
- Department of Laboratory Medicine and Pathobiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Razqallah Hakem
- Department of Laboratory Medicine and Pathobiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5G 1M1, Canada; Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 1L7, Canada; Department of Medical Biophysics, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Brian Raught
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 1L7, Canada; Department of Medical Biophysics, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Alexander F Palazzo
- Department of Biochemistry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Karim Mekhail
- Department of Laboratory Medicine and Pathobiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5G 1M1, Canada.
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2
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Prescott L. SARS-CoV-2 3CLpro whole human proteome cleavage prediction and enrichment/depletion analysis. Comput Biol Chem 2022; 98:107671. [PMID: 35429835 PMCID: PMC8958254 DOI: 10.1016/j.compbiolchem.2022.107671] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 03/21/2022] [Accepted: 03/25/2022] [Indexed: 12/12/2022]
Abstract
A novel coronavirus (SARS-CoV-2) has devastated the globe as a pandemic that has killed millions of people. Widespread vaccination is still uncertain, so many scientific efforts have been directed toward discovering antiviral treatments. Many drugs are being investigated to inhibit the coronavirus main protease, 3CLpro, from cleaving its viral polyprotein, but few publications have addressed this protease’s interactions with the host proteome or their probable contribution to virulence. Too few host protein cleavages have been experimentally verified to fully understand 3CLpro’s global effects on relevant cellular pathways and tissues. Here, I set out to determine this protease’s targets and corresponding potential drug targets. Using a neural network trained on cleavages from 392 coronavirus proteomes with a Matthews correlation coefficient of 0.985, I predict that a large proportion of the human proteome is vulnerable to 3CLpro, with 4898 out of approximately 20,000 human proteins containing at least one putative cleavage site. These cleavages are nonrandomly distributed and are enriched in the epithelium along the respiratory tract, brain, testis, plasma, and immune tissues and depleted in olfactory and gustatory receptors despite the prevalence of anosmia and ageusia in COVID-19 patients. Affected cellular pathways include cytoskeleton/motor/cell adhesion proteins, nuclear condensation and other epigenetics, host transcription and RNAi, ribosomal stoichiometry and nascent-chain detection and degradation, ubiquitination, pattern recognition receptors, coagulation, lipoproteins, redox, and apoptosis. This whole proteome cleavage prediction demonstrates the importance of 3CLpro in expected and nontrivial pathways affecting virulence, lead me to propose more than a dozen potential therapeutic targets against coronaviruses, and should therefore be applied to all viral proteases and subsequently experimentally verified.
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Moon Y. Public Database-Driven Insights Into Aging Stress-Associated Defective Gut Barrier With Low SARS-CoV-2 Receptors. Front Med (Lausanne) 2020; 7:606991. [PMID: 33415119 PMCID: PMC7783319 DOI: 10.3389/fmed.2020.606991] [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: 09/16/2020] [Accepted: 11/30/2020] [Indexed: 11/13/2022] Open
Abstract
The novel coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to a global pandemic, and resulted in high case-fatality rate in the elderly. In addition to typical respiratory responses, ~50% of clinical cases include gastrointestinal symptoms such as diarrhea, vomiting, abdominal pain, and persistent fecal shedding of the virus even after its clearance from the pulmonary system. In the present study, we assessed aging-associated gut transcriptomic responses considering the gastrointestinal symptoms contributing to COVID-19 severity. Intestinal expression of SARS-CoV-2 receptors and defense biomarkers decreased with increasing age. Moreover, aging-associated integrated stress responses (ISR) and mTOR-linked cell metabolic stress signals counteracted gut defense biomarkers. However, SARS-CoV-2 receptor expression was positively associated with gut barrier integrity potently via downregulation of the two stress-responsive signals. Gut transcriptome-based mechanistic prediction implicates that high susceptibility to COVID-19 in the elderly with low SARS-CoV-2 receptors is due to aging stress-associated defective gut defense, providing a new avenue for viral entry receptor-independent interventions.
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Affiliation(s)
- Yuseok Moon
- Laboratory of Mucosal Exposome and Biomodulation, Department of Convergence Medical Sciences, Pusan National University, Yangsan, South Korea
- Graduate Program of Genome Data Sciences, Pusan National University, Yangsan, South Korea
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Maranon DG, Anderson JR, Maranon AG, Wilusz J. The interface between coronaviruses and host cell RNA biology: Novel potential insights for future therapeutic intervention. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 11:e1614. [PMID: 32638509 PMCID: PMC7361139 DOI: 10.1002/wrna.1614] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 05/28/2020] [Accepted: 05/29/2020] [Indexed: 12/17/2022]
Abstract
Coronaviruses, including SARS-Cov-2, are RNA-based pathogens that interface with a large variety of RNA-related cellular processes during infection. These processes include capping, polyadenylation, localization, RNA stability, translation, and regulation by RNA binding proteins or noncoding RNA effectors. The goal of this article is to provide an in-depth perspective on the current state of knowledge of how various coronaviruses interact with, usurp, and/or avoid aspects of these cellular RNA biology machineries. A thorough understanding of how coronaviruses interact with RNA-related posttranscriptional processes in the cell should allow for new insights into aspects of viral pathogenesis as well as identify new potential avenues for the development of anti-coronaviral therapeutics. This article is categorized under: RNA in Disease and Development > RNA in Disease.
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Affiliation(s)
- David G Maranon
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - John R Anderson
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - Abril G Maranon
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - Jeffrey Wilusz
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
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5
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Selinger M, Tykalová H, Štěrba J, Věchtová P, Vavrušková Z, Lieskovská J, Kohl A, Schnettler E, Grubhoffer L. Tick-borne encephalitis virus inhibits rRNA synthesis and host protein production in human cells of neural origin. PLoS Negl Trop Dis 2019; 13:e0007745. [PMID: 31560682 PMCID: PMC6785130 DOI: 10.1371/journal.pntd.0007745] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 10/09/2019] [Accepted: 09/03/2019] [Indexed: 12/11/2022] Open
Abstract
Tick-borne encephalitis virus (TBEV), a member of the genus Flavivirus (Flaviviridae), is a causative agent of a severe neuroinfection. Recently, several flaviviruses have been shown to interact with host protein synthesis. In order to determine whether TBEV interacts with this host process in its natural target cells, we analysed de novo protein synthesis in a human cell line derived from cerebellar medulloblastoma (DAOY HTB-186). We observed a significant decrease in the rate of host protein synthesis, including the housekeeping genes HPRT1 and GAPDH and the known interferon-stimulated gene viperin. In addition, TBEV infection resulted in a specific decrease of RNA polymerase I (POLR1) transcripts, 18S and 28S rRNAs and their precursor, 45-47S pre-rRNA, but had no effect on the POLR3 transcribed 5S rRNA levels. To our knowledge, this is the first report of flavivirus-induced decrease of specifically POLR1 rRNA transcripts accompanied by host translational shut-off. Tick-borne encephalitis virus (TBEV) is a causative agent of a severe human neuroinfection that threatens Europe and Asia. Little is known about the interaction of this neurotropic virus with neural cells, even though this may be important to better understand why or how TBEV can cause high pathogenicity in humans, especially following neural cell infection. Here, we showed that TBEV induced host translational shut-off in cells of neural origin. In addition, TBEV interfered also with the expression of host ribosomal RNAs. Interestingly, the transcriptional shut-off was documented for rRNA species transcribed by RNA polymerase I (18S rRNA, 28S rRNA and their precursor 45-47S pre-rRNA), but not for RNA polymerase III rRNA transcripts (5S rRNA). Artificial inhibition of host translation using cycloheximide resulted in the decrease of all rRNA species. Based on these data, TBEV seems to specifically target transcription of RNA polymerase I. These new findings further increase our understanding of TBEV interactions with a key target cell type.
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Affiliation(s)
- Martin Selinger
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
| | - Hana Tykalová
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
| | - Ján Štěrba
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
| | - Pavlína Věchtová
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
| | - Zuzana Vavrušková
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
| | - Jaroslava Lieskovská
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
| | - Esther Schnettler
- Bernhard-Nocht-Institute for Tropical Medicine, Bernhard-Nocht-Str. 74, Hamburg, Germany
- German Centre for Infection Research (DZIF), partner site Hamburg-Luebeck-Borstel-Riems, Hamburg, Germany
- * E-mail: (ES); (LG)
| | - Libor Grubhoffer
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
- * E-mail: (ES); (LG)
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6
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Interplay between coronavirus, a cytoplasmic RNA virus, and nonsense-mediated mRNA decay pathway. Proc Natl Acad Sci U S A 2018; 115:E10157-E10166. [PMID: 30297408 PMCID: PMC6205489 DOI: 10.1073/pnas.1811675115] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Coronaviruses (CoVs) are important pathogens for humans and domestic animals. The development of effective countermeasures against CoVs requires an understanding of the host pathways that regulate viral gene expression and the viral subversion mechanisms. However, little is known about how the stability of viral mRNAs is controlled. We show that the nonsense-mediated decay (NMD) pathway, which primarily targets aberrant cellular mRNAs for degradation, also induced the degradation of CoV mRNAs that are of cytoplasmic origin. Our study further suggests the importance of CoV-induced inhibition of the NMD pathway, mediated by a viral protein, for efficient CoV replication. The present study highlights an interplay between the NMD pathway and CoVs that modulates viral replication by controlling the stability of viral mRNAs. Coronaviruses (CoVs), including severe acute respiratory syndrome CoV and Middle East respiratory syndrome CoV, are enveloped RNA viruses that carry a large positive-sense single-stranded RNA genome and cause a variety of diseases in humans and domestic animals. Very little is known about the host pathways that regulate the stability of CoV mRNAs, which carry some unusual features. Nonsense-mediated decay (NMD) is a eukaryotic RNA surveillance pathway that detects mRNAs harboring aberrant features and targets them for degradation. Although CoV mRNAs are of cytoplasmic origin, the presence of several NMD-inducing features (including multiple ORFs with internal termination codons that create a long 3′ untranslated region) in CoV mRNAs led us to explore the interplay between the NMD pathway and CoVs. Our study using murine hepatitis virus as a model CoV showed that CoV mRNAs are recognized by the NMD pathway as a substrate, resulting in their degradation. Furthermore, CoV replication induced the inhibition of the NMD pathway, and N protein (a viral structural protein) had an NMD inhibitory function that protected viral mRNAs from rapid decay. Our data further suggest that the NMD pathway interferes with optimal viral replication by degrading viral mRNAs early in infection, before sufficient accumulation of N protein. Our study presents clear evidence for the biological importance of the NMD pathway in controlling the stability of mRNAs and the efficiency of replication of a cytoplasmic RNA virus.
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7
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Rusin A, Seymour C, Mothersill C. Chronic fatigue and immune deficiency syndrome (CFIDS), cellular metabolism, and ionizing radiation: a review of contemporary scientific literature and suggested directions for future research. Int J Radiat Biol 2018; 94:212-228. [DOI: 10.1080/09553002.2018.1422871] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Andrej Rusin
- Department of Biology, McMaster University, Hamilton, Canada
| | - Colin Seymour
- Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Canada
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8
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Abstract
Coronaviruses have large positive-strand RNA genomes that are 5' capped and 3' polyadenylated. The 5'-terminal two-thirds of the genome contain two open reading frames (ORFs), 1a and 1b, that together make up the viral replicase gene and encode two large polyproteins that are processed by viral proteases into 15-16 nonstructural proteins, most of them being involved in viral RNA synthesis. ORFs located in the 3'-terminal one-third of the genome encode structural and accessory proteins and are expressed from a set of 5' leader-containing subgenomic mRNAs that are synthesized by a process called discontinuous transcription. Coronavirus protein synthesis not only involves cap-dependent translation mechanisms but also employs regulatory mechanisms, such as ribosomal frameshifting. Coronavirus replication is known to affect cellular translation, involving activation of stress-induced signaling pathways, and employing viral proteins that affect cellular mRNA translation and RNA stability. This chapter describes our current understanding of the mechanisms involved in coronavirus mRNA translation and changes in host mRNA translation observed in coronavirus-infected cells.
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Affiliation(s)
- K Nakagawa
- The University of Texas Medical Branch, Galveston, TX, United States
| | - K G Lokugamage
- The University of Texas Medical Branch, Galveston, TX, United States
| | - S Makino
- The University of Texas Medical Branch, Galveston, TX, United States; Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch, Galveston, TX, United States; UTMB Center for Tropical Diseases, The University of Texas Medical Branch, Galveston, TX, United States; Sealy Center for Vaccine Development, The University of Texas Medical Branch, Galveston, TX, United States; Institute for Human Infections and Immunity, The University of Texas Medical Branch, Galveston, TX, United States.
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9
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Fung TS, Liao Y, Liu DX. Regulation of Stress Responses and Translational Control by Coronavirus. Viruses 2016; 8:v8070184. [PMID: 27384577 PMCID: PMC4974519 DOI: 10.3390/v8070184] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 06/21/2016] [Accepted: 06/28/2016] [Indexed: 01/02/2023] Open
Abstract
Similar to other viruses, coronavirus infection triggers cellular stress responses in infected host cells. The close association of coronavirus replication with the endoplasmic reticulum (ER) results in the ER stress responses, which impose a challenge to the viruses. Viruses, in turn, have come up with various mechanisms to block or subvert these responses. One of the ER stress responses is inhibition of the global protein synthesis to reduce the amount of unfolded proteins inside the ER lumen. Viruses have evolved the capacity to overcome the protein translation shutoff to ensure viral protein production. Here, we review the strategies exploited by coronavirus to modulate cellular stress response pathways. The involvement of coronavirus-induced stress responses and translational control in viral pathogenesis will also be briefly discussed.
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Affiliation(s)
- To Sing Fung
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
| | - Ying Liao
- Department of Avian Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Ziyue Road 518, Shanghai 200241, China.
| | - Ding Xiang Liu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
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10
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Narendrula R, Mispel-Beyer K, Guo B, Parissenti AM, Pritzker LB, Pritzker K, Masilamani T, Wang X, Lannér C. RNA disruption is associated with response to multiple classes of chemotherapy drugs in tumor cell lines. BMC Cancer 2016; 16:146. [PMID: 26911141 PMCID: PMC4765116 DOI: 10.1186/s12885-016-2197-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Accepted: 02/17/2016] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Cellular stressors and apoptosis-inducing agents have been shown to induce ribosomal RNA (rRNA) degradation in eukaryotic cells. Recently, RNA degradation in vivo was observed in patients with locally advanced breast cancer, where mid-treatment tumor RNA degradation was associated with complete tumor destruction and enhanced patient survival. However, it is not clear how widespread chemotherapy induced "RNA disruption" is, the extent to which it is associated with drug response or what the underlying mechanisms are. METHODS Ovarian (A2780, CaOV3) and breast (MDA-MB-231, MCF-7, BT474, SKBR3) cancer cell lines were treated with several cytotoxic chemotherapy drugs and total RNA was isolated. RNA was also prepared from docetaxel resistant A2780DXL and carboplatin resistant A2780CBN cells following drug exposure. Disruption of RNA was analyzed by capillary electrophoresis. Northern blotting was performed using probes complementary to the 28S and 18S rRNA to determine the origins of degradation bands. Apoptosis activation was assessed by flow cytometric monitoring of annexin-V and propidium iodide (PI) binding to cells and by measuring caspase-3 activation. The link between apoptosis and RNA degradation (disruption) was investigated using a caspase-3 inhibitor. RESULTS All chemotherapy drugs tested were capable of inducing similar RNA disruption patterns. Docetaxel treatment of the resistant A2780DXL cells and carboplatin treatment of the A2780CBN cells did not result in RNA disruption. Northern blotting indicated that two RNA disruption bands were derived from the 3'-end of the 28S rRNA. Annexin-V and PI staining of docetaxel treated cells, along with assessment of caspase-3 activation, showed concurrent initiation of apoptosis and RNA disruption, while inhibition of caspase-3 activity significantly reduced RNA disruption. CONCLUSIONS Supporting the in vivo evidence, our results demonstrate that RNA disruption is induced by multiple chemotherapy agents in cell lines from different tissues and is associated with drug response. Although present, the link between apoptosis and RNA disruption is not completely understood. Evaluation of RNA disruption is thus proposed as a novel and effective biomarker to assess response to chemotherapy drugs in vitro and in vivo.
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MESH Headings
- Antineoplastic Agents/pharmacology
- Apoptosis
- Breast Neoplasms/drug therapy
- Breast Neoplasms/genetics
- Carboplatin/pharmacology
- Caspase 3/metabolism
- Cell Line, Tumor
- Docetaxel
- Dose-Response Relationship, Drug
- Drug Resistance, Neoplasm
- Female
- Humans
- MCF-7 Cells
- Ovarian Neoplasms/drug therapy
- Ovarian Neoplasms/genetics
- RNA Stability/drug effects
- RNA, Ribosomal, 18S/chemistry
- RNA, Ribosomal, 18S/genetics
- RNA, Ribosomal, 28S/chemistry
- RNA, Ribosomal, 28S/genetics
- Taxoids/pharmacology
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Affiliation(s)
| | - Kyle Mispel-Beyer
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, ON, Canada
| | - Baoqing Guo
- Advanced Medical Research Institute of Canada, Sudbury, ON, Canada
- RNA Diagnostics Inc., Toronto, ON, Canada
| | - Amadeo M Parissenti
- Department of Biology, Laurentian University, Sudbury, ON, Canada
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, ON, Canada
- Division of Medical Sciences, Northern Ontario School of Medicine, 935 Ramsey Lake Rd., Sudbury, ON, P3E 2C6, Canada
- Advanced Medical Research Institute of Canada, Sudbury, ON, Canada
- Faculty of Medicine, Division of Oncology, University of Ottawa, Ottawa, ON, Canada
- RNA Diagnostics Inc., Toronto, ON, Canada
| | | | | | | | | | - Carita Lannér
- Department of Biology, Laurentian University, Sudbury, ON, Canada.
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, ON, Canada.
- Division of Medical Sciences, Northern Ontario School of Medicine, 935 Ramsey Lake Rd., Sudbury, ON, P3E 2C6, Canada.
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11
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Cooper DA, Jha BK, Silverman RH, Hesselberth JR, Barton DJ. Ribonuclease L and metal-ion-independent endoribonuclease cleavage sites in host and viral RNAs. Nucleic Acids Res 2014; 42:5202-16. [PMID: 24500209 PMCID: PMC4005677 DOI: 10.1093/nar/gku118] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Ribonuclease L (RNase L) is a metal-ion–independent endoribonuclease associated with antiviral and antibacterial defense, cancer and lifespan. Despite the biological significance of RNase L, the RNAs cleaved by this enzyme are poorly defined. In this study, we used deep sequencing methods to reveal the frequency and location of RNase L cleavage sites within host and viral RNAs. To make cDNA libraries, we exploited the 2′, 3′-cyclic phosphate at the end of RNA fragments produced by RNase L and other metal-ion–independent endoribonucleases. We optimized and validated 2′, 3′-cyclic phosphate cDNA synthesis and Illumina sequencing methods using viral RNAs cleaved with purified RNase L, viral RNAs cleaved with purified RNase A and RNA from uninfected and poliovirus-infected HeLa cells. Using these methods, we identified (i) discrete regions of hepatitis C virus and poliovirus RNA genomes that were profoundly susceptible to RNase L and other single-strand specific endoribonucleases, (ii) RNase L-dependent and RNase L-independent cleavage sites within ribosomal RNAs (rRNAs) and (iii) 2′, 3′-cyclic phosphates at the ends of 5S rRNA and U6 snRNA. Monitoring the frequency and location of metal-ion–independent endoribonuclease cleavage sites within host and viral RNAs reveals, in part, how these enzymes contribute to health and disease.
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Affiliation(s)
- Daphne A Cooper
- Department of Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA, Department of Cancer Biology, Lerner Research Institute, The Cleveland Clinic, Cleveland, OH 44195, USA, Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA and Program in Molecular Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA
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12
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Hamajima R, Ito Y, Ichikawa H, Mitsutake H, Kobayashi J, Kobayashi M, Ikeda M. Degradation of rRNA in BM-N cells from the silkworm Bombyx mori during abortive infection with heterologous nucleopolyhedroviruses. J Gen Virol 2013; 94:2102-2111. [PMID: 23784443 DOI: 10.1099/vir.0.053645-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cell lines derived from the silkworm, Bombyx mori, are only permissive for B. mori nucleopolyhedrovirus (NPV), with other NPVs generally resulting in abortive infection. Here, we demonstrate that rRNA of B. mori BM-N cells undergoes rapid degradation through site-specific cleavage upon infection with NPVs from Autographa californica (AcMNPV), Hyphantria cunea (HycuMNPV), Spodoptera exigua (SeMNPV) and Spodoptera litura (SpltMNPV). No significant decreases in cellular RNA were observed in Ld652Y, Se301, Sf9, SpIm and S2 cells infected with AcMNPV or HycuMNPV, indicating the response is unique to BM-N cells. A transient expression assay using a cosmid library of the HycuMNPV genome demonstrated that HycuMNPV P143 is responsible for rRNA degradation, which was also detected in BM-N cells transfected with plasmids expressing the P143 proteins from AcMNPV, SeMNPV and SpltMNPV. These results indicate that B. mori evolved to acquire a unique antiviral immune mechanism that is activated by P143 proteins from heterologous NPVs.
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Affiliation(s)
- Rina Hamajima
- Laboratory of Sericulture and Entomoresources, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Yuya Ito
- Laboratory of Sericulture and Entomoresources, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Haruka Ichikawa
- Laboratory of Sericulture and Entomoresources, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Hiroshi Mitsutake
- United Graduate School of Agricultural Sciences, Tottori University, Koyama-cho, Minami 4-101, Tottori 680-8553, Japan
| | - Jun Kobayashi
- Faculty of Agriculture, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8515, Japan.,United Graduate School of Agricultural Sciences, Tottori University, Koyama-cho, Minami 4-101, Tottori 680-8553, Japan
| | - Michihiro Kobayashi
- Laboratory of Sericulture and Entomoresources, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Motoko Ikeda
- Laboratory of Sericulture and Entomoresources, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan
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13
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Walsh D, Mathews MB, Mohr I. Tinkering with translation: protein synthesis in virus-infected cells. Cold Spring Harb Perspect Biol 2013; 5:a012351. [PMID: 23209131 DOI: 10.1101/cshperspect.a012351] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Viruses are obligate intracellular parasites, and their replication requires host cell functions. Although the size, composition, complexity, and functions encoded by their genomes are remarkably diverse, all viruses rely absolutely on the protein synthesis machinery of their host cells. Lacking their own translational apparatus, they must recruit cellular ribosomes in order to translate viral mRNAs and produce the protein products required for their replication. In addition, there are other constraints on viral protein production. Crucially, host innate defenses and stress responses capable of inactivating the translation machinery must be effectively neutralized. Furthermore, the limited coding capacity of the viral genome needs to be used optimally. These demands have resulted in complex interactions between virus and host that exploit ostensibly virus-specific mechanisms and, at the same time, illuminate the functioning of the cellular protein synthesis apparatus.
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Affiliation(s)
- Derek Walsh
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA.
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14
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He K, Zhou HR, Pestka JJ. Targets and intracellular signaling mechanisms for deoxynivalenol-induced ribosomal RNA cleavage. Toxicol Sci 2012; 127:382-90. [PMID: 22491426 PMCID: PMC3355321 DOI: 10.1093/toxsci/kfs134] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The trichothecene mycotoxin deoxynivalenol (DON), a known translational inhibitor, induces ribosomal RNA (rRNA) cleavage. Here, we characterized this process relative to (1) specific 18S and 28S ribosomal RNA cleavage sites and (2) identity of specific upstream signaling elements in this pathway. Capillary electrophoresis indicated that DON at concentrations as low as 200 ng/ml evoked selective rRNA cleavage after 6 h and that 1000 ng/ml caused cleavage within 2 h. Northern blot analysis revealed that DON exposure induced six rRNA cleavage fragments from 28S rRNA and five fragments from 18S rRNA. When selective kinase inhibitors were used to identify potential upstream signals, RNA-activated protein kinase (PKR), hematopoietic cell kinase (Hck), and p38 were found to be required for rRNA cleavage, whereas c-Jun N-terminal kinase and extracellular signal-regulated kinase were not. Furthermore, rRNA fragmentation was suppressed by the p53 inhibitors pifithrin-α and pifithrin-μ as well as the pan caspase inhibitor Z-VAD-FMK. Concurrent apoptosis was confirmed by acridine orange/ethidium bromide staining and flow cytometry. DON activated caspases 3, 8, and 9, thus suggesting the possible coinvolvement of both extrinsic and intrinsic apoptotic pathways in rRNA cleavage. Satratoxin G (SG), anisomycin, and ricin also induced specific rRNA cleavage profiles identical to those of DON, suggesting that ribotoxins might share a conserved rRNA cleavage mechanism. Taken together, DON-induced rRNA cleavage is likely to be closely linked to apoptosis activation and appears to involve the sequential activation of PKR/Hck →p38→p53→caspase 8/9→caspase 3.
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Affiliation(s)
- Kaiyu He
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824-1224, USA
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15
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Li D, Wang Q, Liu C, Duan H, Zeng X, Zhang B, Li X, Zhao J, Tang S, Li Z, Xing X, Yang P, Chen L, Zeng J, Zhu X, Zhang S, Zhang Z, Ma L, He Z, Wang E, Xiao Y, Zheng Y, Chen W. Aberrant expression of miR-638 contributes to benzo(a)pyrene-induced human cell transformation. Toxicol Sci 2011; 125:382-91. [PMID: 22048643 DOI: 10.1093/toxsci/kfr299] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Identification of aberrant microRNA (miRNA) expression during chemical carcinogen-induced cell transformation will lead to a better understanding of the substantial role of miRNAs in cancer development. To explore whether aberrant miRNAs expression can be used as biomarkers of chemical exposure in risk assessment of chemical carcinogenesis, we analyzed miRNA expression profiles of human bronchial epithelial cells expressing an oncogenic allele of H-Ras (HBER) at different stages of transformation induced by benzo(a)pyrene (BaP) by miRNA array. It revealed 12 miRNAs differentially expressed in HBER cells at both pretransformed and transformed stages. Differentially expressed miRNAs were confirmed in transformed cells and examined in 50 pairs of primary human non-small-cell lung cancer (NSCLC) tissues using real-time PCR. Among these miRNAs, downregulation of miR-638 was found in 68% (34/50) of NSCLC tissues. However, the expression of miR-638 in HBER cells increased upon treatment of BaP in a dose-dependent manner. The expression of miR-638 was also examined in peripheral lymphocytes from 86 polycyclic aromatic hydrocarbons (PAHs)-exposed (PE) workers. We found that the average expression level of miR-638 in peripheral lymphocytes from 86 PE workers increased by 72% compared with control group. The levels of miR-638 were correlated with the concentration of urinary 1-hydroxypyrene (1-OHP) and external levels of PAHs. Overexpression of miR-638 aggravated cell DNA damage induced by BaP, which might be mediated by suppression of breast cancer 1 (BRCA1), one of the target genes of miR-638. In summary, we suggest that miR-638 is involved in the BaP-induced carcinogenesis by targeting BRCA1.
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Affiliation(s)
- Daochuan Li
- Department of Toxicology, Guangdong Provincial Key Laboratory of Food, Nutrition and Health, School of Public Health, Sun Yat-sen University, Guangzhou 510080, People's Republic of China
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16
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Maestre AM, Garzón A, Rodríguez D. Equine torovirus (BEV) induces caspase-mediated apoptosis in infected cells. PLoS One 2011; 6:e20972. [PMID: 21698249 PMCID: PMC3115971 DOI: 10.1371/journal.pone.0020972] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2011] [Accepted: 05/16/2011] [Indexed: 12/26/2022] Open
Abstract
Toroviruses are gastroenteritis causing agents that infect different animal species and humans. To date, very little is known about how toroviruses cause disease. Here, we describe for the first time that the prototype member of this genus, the equine torovirus Berne virus (BEV), induces apoptosis in infected cells at late times postinfection. Observation of BEV infected cells by electron microscopy revealed that by 24 hours postinfection some cells exhibited morphological characteristics of apoptotic cells. Based on this finding, we analyzed several apoptotic markers, and observed protein synthesis inhibition, rRNA and DNA degradation, nuclear fragmentation, caspase-mediated cleavage of PARP and eIF4GI, and PKR and eIF2α phosphorylation, all these processes taking place after peak virus production. We also determined that both cell death receptor and mitochondrial pathways are involved in the apoptosis process induced by BEV. BEV-induced apoptosis at late times postinfection, once viral progeny are produced, could facilitate viral dissemination in vivo and contribute to viral pathogenesis.
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Affiliation(s)
- Ana M. Maestre
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, Madrid, Spain
| | - Ana Garzón
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, Madrid, Spain
| | - Dolores Rodríguez
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, Madrid, Spain
- * E-mail:
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17
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Kamitani W, Huang C, Narayanan K, Lokugamage KG, Makino S. A two-pronged strategy to suppress host protein synthesis by SARS coronavirus Nsp1 protein. Nat Struct Mol Biol 2009; 16:1134-40. [PMID: 19838190 PMCID: PMC2784181 DOI: 10.1038/nsmb.1680] [Citation(s) in RCA: 284] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Accepted: 08/21/2009] [Indexed: 01/13/2023]
Abstract
The SARS coronavirus protein nsp1 can suppress host gene expression at a post-transcriptional level, with previous work showing a reduction in mRNA abundance. Now a direct effect on protein synthesis is revealed, as nsp1 modifies transcripts and also inactivates the 40S ribosomal subunit. Severe acute respiratory syndrome coronavirus nsp1 protein suppresses host gene expression, including type I interferon production, by promoting host mRNA degradation and inhibiting host translation, in infected cells. We present evidence that nsp1 uses a novel, two-pronged strategy to inhibit host translation and gene expression. Nsp1 bound to the 40S ribosomal subunit and inactivated the translational activity of the 40S subunits. Furthermore, the nsp1–40S ribosome complex induced the modification of the 5′ region of capped mRNA template and rendered the template RNA translationally incompetent. Nsp1 also induced RNA cleavage in templates carrying the internal ribosome entry site (IRES) from encephalomyocarditis virus, but not in those carrying IRES elements from hepatitis C or cricket paralysis viruses, demonstrating that the nsp1-induced RNA modification was template-dependent. We speculate that the mRNAs that underwent the nsp1-mediated modification are marked for rapid turnover by the host RNA degradation machinery.
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Affiliation(s)
- Wataru Kamitani
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, USA
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18
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Inhibition of protein kinase R activation and upregulation of GADD34 expression play a synergistic role in facilitating coronavirus replication by maintaining de novo protein synthesis in virus-infected cells. J Virol 2009; 83:12462-72. [PMID: 19776135 DOI: 10.1128/jvi.01546-09] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
A diversity of strategies is evolved by RNA viruses to manipulate the host translation machinery in order to create an optimal environment for viral replication and progeny production. One of the common viral targets is the alpha subunit of eukaryotic initiation factor 2 (eIF-2alpha). In this report, we show that phosphorylation of eIF-2alpha was severely suppressed in human and animal cells infected with the coronavirus infectious bronchitis virus (IBV). To understand whether this suppression is through inhibition of protein kinase R (PKR), the double-stranded-RNA-dependent kinase that is one of the main kinases responsible for phosphorylation of eIF-2alpha, cells infected with IBV were analyzed by Western blotting. The results showed that the level of phosphorylated PKR was greatly reduced in IBV-infected cells. Overexpression of IBV structural and nonstructural proteins (nsp) demonstrated that nsp2 is a weak PKR antagonist. Furthermore, GADD34, a component of the protein phosphatase 1 (PP1) complex, which dephosphorylates eIF-2alpha, was significantly induced in IBV-infected cells. Inhibition of the PP1 activity by okadaic acid and overexpression of GADD34, eIF-2alpha, and PKR, as well as their mutant constructs in virus-infected cells, showed that these viral regulatory strategies played a synergistic role in facilitating coronavirus replication. Taken together, these results confirm that IBV has developed a combination of two mechanisms, i.e., blocking PKR activation and inducing GADD34 expression, to maintain de novo protein synthesis in IBV-infected cells and, meanwhile, to enhance viral replication.
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19
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Mroczek S, Kufel J. Apoptotic signals induce specific degradation of ribosomal RNA in yeast. Nucleic Acids Res 2008; 36:2874-88. [PMID: 18385160 PMCID: PMC2396418 DOI: 10.1093/nar/gkm1100] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Revised: 11/26/2007] [Accepted: 11/26/2007] [Indexed: 11/13/2022] Open
Abstract
Organisms exposed to reactive oxygen species, generated endogenously during respiration or by environmental conditions, undergo oxidative stress. Stress response can either repair the damage or activate one of the programmed cell death (PCD) mechanisms, for example apoptosis, and finally end in cell death. One striking characteristic, which accompanies apoptosis in both vertebrates and yeast, is a fragmentation of cellular DNA and mammalian apoptosis is often associated with degradation of different RNAs. We show that in yeast exposed to stimuli known to induce apoptosis, such as hydrogen peroxide, acetic acid, hyperosmotic stress and ageing, two large subunit ribosomal RNAs, 25S and 5.8S, became extensively degraded with accumulation of specific intermediates that differ slightly depending on cell death conditions. This process is most likely endonucleolytic, is correlated with stress response, and depends on the mitochondrial respiratory status: rRNA is less susceptible to degradation in respiring cells with functional defence against oxidative stress. In addition, RNA fragmentation is independent of two yeast apoptotic factors, metacaspase Yca1 and apoptosis-inducing factor Aif1, but it relies on the apoptotic chromatin condensation induced by histone H2B modifications. These data describe a novel phenotype for certain stress- and ageing-related PCD pathways in yeast.
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Affiliation(s)
| | - Joanna Kufel
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5a, 02-106 Warsaw, Poland
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20
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Coronavirus infection modulates the unfolded protein response and mediates sustained translational repression. J Virol 2008; 82:4492-501. [PMID: 18305036 DOI: 10.1128/jvi.00017-08] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
During coronavirus replication, viral proteins induce the formation of endoplasmic reticulum (ER)-derived double-membrane vesicles for RNA synthesis, and viral structural proteins assemble virions at the ER-Golgi intermediate compartment. We hypothesized that the association and intense utilization of the ER during viral replication would induce the cellular unfolded protein response (UPR), a signal transduction cascade that acts to modulate translation, membrane biosynthesis, and the levels of ER chaperones. Here, we report that infection by the murine coronavirus mouse hepatitis virus (MHV) triggers the proximal UPR transducers, as revealed by monitoring the IRE1-mediated splicing of XBP-1 mRNA and the cleavage of ATF6alpha. However, we detected minimal downstream induction of UPR target genes, including ERdj4, ER degradation-enhancing alpha-mannosidase-like protein, and p58(IPK), or expression of UPR reporter constructs. Translation initiation factor eIF2alpha is highly phosphorylated during MHV infection, and translation of cellular mRNAs is attenuated. Furthermore, we found that the critical homeostasis regulator GADD34, which recruits protein phosphatase 1 to dephosphorylate eIF2alpha during the recovery phase of the UPR, is not expressed during MHV infection. These results suggest that MHV modifies the UPR by impeding the induction of UPR-responsive genes, thereby favoring a sustained shutdown of the synthesis of host cell proteins while the translation of viral proteins escalates. The role of this modified response and its potential relevance to viral mechanisms for the evasion of innate defense signaling pathways during coronavirus replication are discussed.
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21
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Silverman RH. Viral encounters with 2',5'-oligoadenylate synthetase and RNase L during the interferon antiviral response. J Virol 2007; 81:12720-9. [PMID: 17804500 PMCID: PMC2169107 DOI: 10.1128/jvi.01471-07] [Citation(s) in RCA: 460] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Robert H Silverman
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue NB40, Cleveland, OH 44195, USA.
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22
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Yang CW, Yang YN, Liang PH, Chen CM, Chen WL, Chang HY, Chao YS, Lee SJ. Novel small-molecule inhibitors of transmissible gastroenteritis virus. Antimicrob Agents Chemother 2007; 51:3924-31. [PMID: 17709464 PMCID: PMC2151441 DOI: 10.1128/aac.00408-07] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We used swine testicle (ST) cells infected with transmissible gastroenteritis virus (TGEV) and an indirect immunofluorescent assay with antibodies against TGEV spike and nucleocapsid proteins to screen small-molecule compounds that inhibit TGEV replication. Analogues of initial hits were collected and subjected to a 3CL protease (3CL(pro)) inhibition assay with recombinant 3CL(pro) and a fluorogenic peptide substrate. A series of benzothiazolium compounds were found to have inhibitory activity against TGEV 3CL(pro) and to exert anti-TGEV activities in terms of viral protein and RNA replication in TGEV-infected ST cells, with consequent protection of TGEV-infected ST cells from cytopathic effect by blocking the activation of caspase-3.
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Affiliation(s)
- Cheng-Wei Yang
- Division of Biotechnology and Pharmaceutical Research, National Health Research Institute, 35, Keyan Road, Zhunan Town, Miaoli County 350, Taiwan, Republic of China
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23
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Rippa S, Adenier H, Derbaly M, Béven L. The peptaibol alamethicin induces an rRNA-cleavage-associated death in Arabidopsis thaliana. Chem Biodivers 2007; 4:1360-73. [PMID: 17589869 DOI: 10.1002/cbdv.200790116] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The plant-metabolic response to amphipathic peptides produced by the soil fungi of the genus Trichoderma remains largely unknown. The present investigation was undertaken to examine the death process in alamethicin-treated Arabidopsis thaliana plantlets. The rapid death triggered by alamethicin (at 50 microM) was shown to be associated with protein-synthesis arrest and with specific cleavage of 18S and 25S ribosomal RNA. The use of an inhibitor of nitric oxide (NO) synthases and of an NO scavenger suggested that rRNA cleavage was suppressed by NO. Experiments conducted with a synthetic alamethicin analogue, in which all alpha-aminoisobutyric acid (Aib) residues have been replaced by leucine moieties, showed that the non-coded residues are essential for the ability of the peptaibol to induce rRNA cleavage in Arabidopsis. Our data indicate that further investigations on the mode of action of alamethicin in planta could be of great interest to study the death-signaling pathway associated with rRNA degradation in plants.
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Affiliation(s)
- Sonia Rippa
- Université de Technologie de Compiègne, CNRS, UMR 6022 Génie Enzymatique et Cellulaire, Compiègne Cedex, France
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24
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Raaben M, Groot Koerkamp MJA, Rottier PJM, de Haan CAM. Mouse hepatitis coronavirus replication induces host translational shutoff and mRNA decay, with concomitant formation of stress granules and processing bodies. Cell Microbiol 2007; 9:2218-29. [PMID: 17490409 PMCID: PMC7162177 DOI: 10.1111/j.1462-5822.2007.00951.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Many viruses, including coronaviruses, induce host translational shutoff, while maintaining synthesis of their own gene products. In this study we performed genome‐wide microarray analyses of the expression patterns of mouse hepatitis coronavirus (MHV)‐infected cells. At the time of MHV‐induced host translational shutoff, downregulation of numerous mRNAs, many of which encode protein translation‐related factors, was observed. This downregulation, which is reminiscent of a cellular stress response, was dependent on viral replication and caused by mRNA decay. Concomitantly, phosphorylation of the eukaryotic translation initiation factor 2α was increased in MHV‐infected cells. In addition, stress granules and processing bodies appeared, which are sites for mRNA stalling and degradation respectively. We propose that MHV replication induces host translational shutoff by triggering an integrated stress response. However, MHV replication per se does not appear to benefit from the inhibition of host protein synthesis, at least in vitro, since viral replication was not negatively affected but rather enhanced in cells with impaired translational shutoff.
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Affiliation(s)
- Matthijs Raaben
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
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25
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Sobol PT, Mossman KL. ICP0 prevents RNase L-independent rRNA cleavage in herpes simplex virus type 1-infected cells. J Virol 2007; 80:218-25. [PMID: 16352546 PMCID: PMC1317541 DOI: 10.1128/jvi.80.1.218-225.2006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The classical interferon (IFN)-dependent antiviral response to viral infection involves the regulation of IFN-stimulated genes (ISGs), one being the gene encoding cellular endoribonuclease RNase L, which arrests protein synthesis and induces apoptosis by nonspecifically cleaving rRNA. Recently, the herpes simplex virus type 1 (HSV-1) protein ICP0 has been shown to block the induction of ISGs by subverting the IFN pathway upstream of the 2'-5'-oligoadenylate synthetase (OAS)/RNase L pathway. We report that ICP0 also prevents rRNA degradation at late stages of HSV-1 infection, independent of its E3 ubiquitin ligase activity, and that the resultant rRNA degradation is independent of the classical RNase L antiviral pathway. Moreover, the degradation is independent of the viral RNase vhs and is independent of IFN response factor 3. These studies indicate the existence of another, previously unidentified, RNase that is part of the host antiviral response to viral infection.
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Affiliation(s)
- Paul T Sobol
- Department of Biochemistry and Biomedical Sciences, Centre for Gene Therapeutics, McMaster University, Hamilton, Ontario, Canada L8N 3Z5
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26
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Ye Y, Hauns K, Langland JO, Jacobs BL, Hogue BG. Mouse hepatitis coronavirus A59 nucleocapsid protein is a type I interferon antagonist. J Virol 2006; 81:2554-63. [PMID: 17182678 PMCID: PMC1865977 DOI: 10.1128/jvi.01634-06] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The recent emergence of several new coronaviruses, including the etiological cause of severe acute respiratory syndrome, has significantly increased the importance of understanding virus-host cell interactions of this virus family. We used mouse hepatitis virus (MHV) A59 as a model to gain insight into how coronaviruses affect the type I alpha/beta interferon (IFN) system. We demonstrate that MHV is resistant to type I IFN. Protein kinase R (PKR) and the alpha subunit of eukaryotic translation initiation factor are not phosphorylated in infected cells. The RNase L activity associated with 2',5'-oligoadenylate synthetase is not activated or is blocked, since cellular RNA is not degraded. These results are consistent with lack of protein translation shutoff early following infection. We used a well-established recombinant vaccinia virus (VV)-based expression system that lacks the viral IFN antagonist E3L to screen viral genes for their ability to rescue the IFN sensitivity of the mutant. The nucleocapsid (N) gene rescued VVDeltaE3L from IFN sensitivity. N gene expression prevents cellular RNA degradation and partially rescues the dramatic translation shutoff characteristic of the VVDeltaE3L virus. However, it does not prevent PKR phosphorylation. The results indicate that the MHV N protein is a type I IFN antagonist that likely plays a role in circumventing the innate immune response.
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Affiliation(s)
- Ye Ye
- The Biodesign Institute, P.O. Box 875401, Arizona State University, Tempe, AZ 85287-5401, USA
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27
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Zorzitto J, Galligan CL, Ueng JJM, Fish EN. Characterization of the antiviral effects of interferon-alpha against a SARS-like coronoavirus infection in vitro. Cell Res 2006; 16:220-9. [PMID: 16474437 PMCID: PMC7091892 DOI: 10.1038/sj.cr.7310030] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Interferon (IFN)-αs bind to and activate their cognate cell surface receptor to invoke an antiviral response in target cells. Well-described receptor-mediated signaling events result in transcriptional regulation of IFN sensitive genes, effectors of this antiviral response. Results from a pilot study to evaluate the clinical efficacy of IFN-α treatment of SARS patients provided evidence for IFN-inducible resolution of disease. In this report we examined the contribution of IFN-inducible phosphorylation-activation of specific signaling effectors to protection from infection by a SARS-related murine coronavirus, MHV-1. As anticipated, the earliest receptor-activation event, Jak1 phosphorylation, is critical for IFN-inducible protection from MHV-1 infection. Additionally, we provide evidence for the contribution of two kinases, the MAP kinase p38MAPK, and protein kinase C (PKC) δ to antiviral protection from MHV-1 infection. Notably, our data suggest that MHV-1 infection, as for the Urbani SARS coronoavirus, inhibits an IFN response, inferred from the lack of activation of pkr and 2′5′-oas, genes associated with mediating the antiviral activities of IFN-αs. To identify potential target genes that are activated downstream of the IFN-inducible signaling effectors we identified, and that mediate protection from coronavirus infection, we examined the gene expression profiles in the peripheral blood mononuclear cells of SARS patients who received IFN treatment. A subset of differentially regulated genes were distinguished with functional properties associated with antimicrobial activities.
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Affiliation(s)
- Joanna Zorzitto
- Department of Immunology, University of Toronto, Toronto, M5G 2M1 Ontario Canada
| | - Carole L Galligan
- Toronto General Research Institute, University Health Network, Toronto, M5G 2M1 Ontario Canada
| | - Joanna JM Ueng
- Department of Immunology, University of Toronto, Toronto, M5G 2M1 Ontario Canada
| | - Eleanor N Fish
- Department of Immunology, University of Toronto, Toronto, M5G 2M1 Ontario Canada
- Toronto General Research Institute, University Health Network, Toronto, M5G 2M1 Ontario Canada
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28
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Enjuanes L, Almazán F, Sola I, Zuñiga S. Biochemical aspects of coronavirus replication and virus-host interaction. Annu Rev Microbiol 2006; 60:211-30. [PMID: 16712436 DOI: 10.1146/annurev.micro.60.080805.142157] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Infection by different coronaviruses (CoVs) causes alterations in the transcriptional and translational patterns, cell cycle, cytoskeleton, and apoptosis pathways of the host cells. In addition, CoV infection may cause inflammation, alter immune and stress responses, and modify the coagulation pathways. The balance between the up- and downregulated genes could explain the pathogenesis caused by these viruses. We review specific aspects of CoV-host interactions. CoV genome replication takes place in the cytoplasm in a membrane-protected microenvironment and may control the cell machinery by locating some of their proteins in the host cell nucleus. CoVs initiate translation by cap-dependent and cap-independent mechanisms. CoV transcription involves a discontinuous RNA synthesis (template switching) during the extension of a negative copy of the subgenomic mRNAs. The requirement for base-pairing during transcription has been formally demonstrated in arteriviruses and CoVs. CoV N proteins have RNA chaperone activity that may help initiate template switching. Both viral and cellular proteins are required for replication and transcription, and the role of selected proteins is addressed.
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Affiliation(s)
- Luis Enjuanes
- Department of Molecular and Cell Biology, CNB, CSIC, 28049 Madrid, Spain.
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29
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Hoat TX, Nakayashiki H, Tosa Y, Mayama S. Specific cleavage of ribosomal RNA and mRNA during victorin-induced apoptotic cell death in oat. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2006; 46:922-33. [PMID: 16805727 DOI: 10.1111/j.1365-313x.2006.02752.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Here we report that rRNA and mRNA are specifically degraded in oat (Avena sativa L.) cells during apoptotic cell death induced by victorin, a host-selective toxin produced by Cochliobolus victoriae. Northern analysis indicated that rRNA species from the cytosol, mitochondria and chloroplasts were all degraded via specific degradation intermediates during victorin-induced apoptotic cell death but, in contrast, they were randomly digested in necrotic cell death induced by 30 mM CuSO(4) and heat shock. This indicates that specific rRNA cleavage could be controlled by an intrinsic program. We also observed specific cleavage of mRNA of housekeeping genes such as actin and ubiquitin during victorin-induced cell death. Interestingly, no victorin-induced mRNA degradation was detected with stress-responding genes such as PR-1, PR-10 and GPx throughout the experimental period. The RNA degradation mostly, but not always, occurred in parallel with DNA laddering, but pharmacological studies indicated that these processes are regulated by different signaling pathways with some overlapping upstream signals.
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Affiliation(s)
- Trinh X Hoat
- Laboratory of Plant Pathology, Graduate School of Science and Technology, Kobe University, Rokkodai, Nada-ku, Kobe 657-8501, Japan
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Scherbik SV, Paranjape JM, Stockman BM, Silverman RH, Brinton MA. RNase L plays a role in the antiviral response to West Nile virus. J Virol 2006; 80:2987-99. [PMID: 16501108 PMCID: PMC1395436 DOI: 10.1128/jvi.80.6.2987-2999.2006] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Alleles at the Flv locus determine disease outcome after a flavivirus infection in mice. Although comparable numbers of congenic resistant and susceptible mouse embryo fibroblasts (MEFs) are infected by the flavivirus West Nile virus (WNV), resistant MEFs produce approximately 100- to 150-fold lower titers than susceptible ones and flavivirus titers in the brains of resistant and susceptible animals can differ by >10,000-fold. The Flv locus was previously identified as the 2'-5' oligoadenylate synthetase 1b (Oas1b) gene. Oas gene expression is up-regulated by interferon (IFN), and after activation by double-stranded RNA, some mouse synthetases produce 2-5A, which activates latent RNase L to degrade viral and cellular RNAs. To determine whether the lower levels of intracellular flavivirus genomic RNA from resistant mice detected in cells at all times after infection were mediated by RNase L, RNase L activity levels in congenic resistant and susceptible cells were compared. Similar moderate levels of RNase L activation by transfected 2-5A were observed in both types of uninfected cells. After WNV infection, the mRNAs of IFN-beta and three Oas genes were up-regulated to similar levels in both types of cells. However, significant levels of RNase L activity were not detected until 72 h after WNV infection and the patterns of viral RNA cleavage products generated were similar in both types of cells. When RNase L activity was down-regulated in resistant cells via stable expression of a dominant negative RNase L mutant, approximately 5- to 10-times-higher yields of WNV were produced. Similarly, about approximately 5- to 10-times-higher virus yields were produced by susceptible C57BL/6 RNase L-/- cells compared to RNase L+/+ cells that were either left untreated or pretreated with IFN and/or poly(I) . poly(C). The data indicate that WNV genomic RNA is susceptible to RNase L cleavage and that RNase L plays a role in the cellular antiviral response to flaviviruses. The results suggest that RNase L activation is not a major component of the Oas1b-mediated flavivirus resistance phenotype.
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Affiliation(s)
- Svetlana V Scherbik
- Department of Biology, Georgia State University, P.O. Box 4010, Atlanta, Georgia 30302-4010, USA
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Uno T, Hirabayashi K, Murai M, Yano J, Ozato K. The role of IFN regulatory factor-3 in the cytotoxic activity of NS-9, a polyinosinic-polycytidylic acid/cationic liposome complex, against tumor cells. Mol Cancer Ther 2005; 4:799-805. [PMID: 15897244 DOI: 10.1158/1535-7163.mct-04-0317] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
NS-9 is a complex of polyinosinic-polycytidylic acid and a novel cationic liposome, LIC-101. The complex has strong cytotoxic activity against tumor cells derived from epithelial or fibroblastic cells. We have investigated the mechanism of the cytotoxic activity of NS-9 using knockdown cells in which the expression of proteins of interest was inhibited by RNA interference. NS-9 showed strong cytotoxic activity against knockdown cells with reduced expression of double-stranded RNA-dependent protein kinase, RNase L, or IFN-alpha/beta receptor, but showed no cytotoxic activity against IFN regulatory factor-3 (IRF3) knockdown cells. In IRF3-knockdown cells, NS-9 also did not induce either the DNA fragmentation or the rRNA degradation observed in negative control cells. We conclude that IRF3 plays a crucial role in the cytotoxic activity of NS-9 against tumor cells, whereas RNA-dependent protein kinase, RNase L, or type I IFNs are not important for its activity.
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Affiliation(s)
- Tomonori Uno
- Discovery Research Laboratories, Nippon Shinyaku Co., Ltd., 14 Nishinosho-Monguchi-cho, Kisshoin, Minami, Kyoto 601-8550, Japan.
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Desloges N, Rahaus M, Wolff MH. Varicella-zoster virus does not significantly induce cell defence mechanism mediated by the 2-5A/RNase L pathway during its replication cycle. Med Microbiol Immunol 2005; 194:25-31. [PMID: 15107989 DOI: 10.1007/s00430-004-0220-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The 2-5A/RNase L pathway belongs to the antiviral system induced by interferon (IFN). RNase L is an inactive endoribonuclease which is activated by 2'-5' oligoadenylate (2-5A) synthesized by 2',5'-oligoadenylate synthetases. Once activated, RNase L cleaves mRNA, inhibiting the protein synthesis, as well as 28S and 18S ribosomal RNA (rRNA), leading to ribosomal inactivation. In this study, we investigate the role of the RNase L pathway as a cell defence mechanism during Varicella-zoster virus (VZV) replication, and the importance of a 68-kDa protein named RNase L inhibitor (RLI), which specifically inhibits RNase L. We demonstrate that the RNase L and RLI transcripts levels remain constant in VZV-infected cells for 24 h and 12 h, respectively, after which they decrease until the end of the viral cycle. VZV does not significantly modulate the protein level of RNase L during the course of infection. Using an rRNA cleavage assay to analyse the RNase L catalytic activity, we demonstrate that VZV replication leads to a minimal cleavage of rRNA. Moreover, the overexpression of RLI in a permissive cell line has no significant effect on the VZV replication. We conclude that RNase L does not constitute a major cell defence mechanism against the VZV infection.
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Affiliation(s)
- Nathalie Desloges
- University of Witten/Herdecke, Institute of Microbiology and Virology, Germany
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Imbeaud S, Graudens E, Boulanger V, Barlet X, Zaborski P, Eveno E, Mueller O, Schroeder A, Auffray C. Towards standardization of RNA quality assessment using user-independent classifiers of microcapillary electrophoresis traces. Nucleic Acids Res 2005; 33:e56. [PMID: 15800207 PMCID: PMC1072807 DOI: 10.1093/nar/gni054] [Citation(s) in RCA: 374] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
While it is universally accepted that intact RNA constitutes the best representation of the steady-state of transcription, there is no gold standard to define RNA quality prior to gene expression analysis. In this report, we evaluated the reliability of conventional methods for RNA quality assessment including UV spectroscopy and 28S:18S area ratios, and demonstrated their inconsistency. We then used two new freely available classifiers, the Degradometer and RIN systems, to produce user-independent RNA quality metrics, based on analysis of microcapillary electrophoresis traces. Both provided highly informative and valuable data and the results were found highly correlated, while the RIN system gave more reliable data. The relevance of the RNA quality metrics for assessment of gene expression differences was tested by Q-PCR, revealing a significant decline of the relative expression of genes in RNA samples of disparate quality, while samples of similar, even poor integrity were found highly comparable. We discuss the consequences of these observations to minimize artifactual detection of false positive and negative differential expression due to RNA integrity differences, and propose a scheme for the development of a standard operational procedure, with optional registration of RNA integrity metrics in public repositories of gene expression data.
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Affiliation(s)
- Sandrine Imbeaud
- Array s/IMAGE, Genexpress, Functional Genomics and Systems Biology for Health LGN-UMR 7091, CNRS and Pierre and Marie Curie University of Paris 6, 7, rue Guy Môquet, 94801 Villejuif, France.
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Goswami BB, Kulka M, Ngo D, Cebula TA. Apoptosis induced by a cytopathic hepatitis A virus is dependent on caspase activation following ribosomal RNA degradation but occurs in the absence of 2'-5' oligoadenylate synthetase. Antiviral Res 2004; 63:153-66. [PMID: 15451183 PMCID: PMC7127220 DOI: 10.1016/j.antiviral.2004.02.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2003] [Accepted: 02/23/2004] [Indexed: 12/26/2022]
Abstract
We have presented previously evidence that the cytopathogenic 18f strain of hepatitis A virus (HAV) induced degradation of ribosomal RNA (rRNA) in infected cells [Arch. Virol. 148 (2003) 1275–1300]. In contrast, the non-cytopathogenic parent virus HM175 clone 1 had no effect on rRNA integrity. We present here data showing that rRNA degradation is followed by apoptosis accompanied by characteristic DNA laddering in the cytoplasm of 18f infected cells. The DNA laddering coincided with the detection of caspase 3 and PARP-1 cleavage and was dependent upon activation of the caspase pathway, since treatment with Z-VAD-FMK, a pan-caspase inhibitor, inhibited both events. RNase L mRNA was present in both virus-infected and uninfected cells. Messenger RNA for the interferon inducible enzyme 2′–5′ oligoadenylate synthetase (2′–5′ OAS), which polymerizes ATP into 2′–5′ oligo adenylate (2–5A, the activator of RNase L) in the presence of double-stranded RNA, was not detected following virus infection. 2′–5′ OAS mRNA was induced by treatment of the cells with interferon-β (IFN-β). IFN-β mRNA was marginally induced following infection. However, phosphorylated STAT 1, a key regulator of interferon-stimulated gene transcription was not detected in virus infected cells. STAT 1 phosphorylation in response to IFN treatment was lower in virus-infected cells, compared to uninfected cells treated with interferon, suggesting that 18f virus infection interferes with interferon signaling. The results suggest that 18f infection causes the induction of a 2–5A independent RNase L like activity.
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Affiliation(s)
- Biswendu B Goswami
- Division of Molecular Biology, Office of Applied Research and Safety Assessment, Food and Drug Administration, HFS-025, OARSA, FDA, 8301 Muirkirk Road, Laurel, MD 20708, USA,
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Abstract
Mouse hepatitis virus (MHV) replication in actively growing DBT and 17Cl-1 cells resulted in the inhibition of host cellular DNA synthesis and the accumulation of infected cells in the G(0)/G(1) phase of the cell cycle. UV-irradiated MHV failed to inhibit host cellular DNA synthesis. MHV infection in quiescent 17Cl-1 cells that had been synchronized in the G(0) phase by serum deprivation prevented infected cells from entering the S phase after serum stimulation. MHV replication inhibited hyperphosphorylation of the retinoblastoma protein (pRb), the event that is necessary for cell cycle progression through late G(1) and into the S phase. While the amounts of the cellular cyclin-dependent kinase (Cdk) inhibitors p21(Cip1), p27(Kip1), and p16(INK4a) did not change in infected cells, MHV infection in asynchronous cultures induced a clear reduction in the amounts of Cdk4 and G(1) cyclins (cyclins D1, D2, D3, and E) in both DBT and 17Cl-1 cells and a reduction in Cdk6 levels in 17Cl-1 cells. Infection also resulted in a decrease in Cdk2 activity in both cell lines. MHV infection in quiescent 17Cl-1 cells prevented normal increases in Cdk4, Cdk6, cyclin D1, and cyclin D3 levels after serum stimulation. The amounts of cyclin D2 and cyclin E were not increased significantly after serum stimulation in mock-infected cells, whereas they were decreased in MHV-infected cells, suggesting the possibility that MHV infection may induce cyclin D2 and cyclin E degradation. Our data suggested that a reduction in the amounts of G(1) cyclin-Cdk complexes in MHV-infected cells led to a reduction in Cdk activities and insufficient hyperphosphorylation of pRb, resulting in inhibition of the cell cycle in the G(0)/G(1) phase.
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Affiliation(s)
- Chun-Jen Chen
- Department of Microbiology and Immunology, The University of Texas Medical Branch at Galveston, MRB 4.146, 301 University Blvd., Galveston, TX 77555-1019, USA
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Bunyard P, Handley M, Pollara G, Rutault K, Wood I, Chaudry M, Alderman C, Foreman J, Katz DR, Chain BM. Ribotoxic stress activates p38 and JNK kinases and modulates the antigen-presenting activity of dendritic cells. Mol Immunol 2003; 39:815-27. [PMID: 12617997 DOI: 10.1016/s0161-5890(02)00262-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Initiation of adaptive immunity requires activation of dendritic cells (DC) by "danger" signals. This study examines the functional consequences of activating a cellular stress response in human DC. Anisomycin, a potent inducer of this "stress" response, selectively activates p38 kinase in DC at low concentrations, and both p38 kinases and JNKs at higher concentrations. Activation of p38, was accompanied by an increase in the potency of dendritic cells to activate T cells. In contrast to LPS, anisomycin had no effect on the expression of several DC activation markers. Anisomycin synergised with LPS in driving release of IL-12 and TNF-alpha. Anisomycin also enhanced the formation of clusters between DC and T cells. Enhanced cytokine release and clustering were both inhibited by the selective p38 alpha and p38 beta inhibitor SB203580. This study demonstrates that the cellular stress response, mediated via p38 kinases, plays an important role in the regulation of several aspects of DC function.
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Affiliation(s)
- Peter Bunyard
- Department of Immunology and Molecular Biology, Windeyer Institute for Medical Sciences, University College London, 46 Cleveland Street, London W1T 4JF, UK
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Banerjee S, Narayanan K, Mizutani T, Makino S. Murine coronavirus replication-induced p38 mitogen-activated protein kinase activation promotes interleukin-6 production and virus replication in cultured cells. J Virol 2002; 76:5937-48. [PMID: 12021326 PMCID: PMC136219 DOI: 10.1128/jvi.76.12.5937-5948.2002] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Analyses of mitogen-activated protein kinases (MAPKs) in a mouse hepatitis virus (MHV)-infected macrophage-derived J774.1 cell line showed activation of two MAPKs, p38 MAPK and c-Jun N-terminal kinase (JNK), but not of extracellular signal-regulated kinase (ERK). Activation of MAPKs was evident by 6 h postinfection. However, UV-irradiated MHV failed to activate MAPKs, which demonstrated that MHV replication was necessary for their activation. Several other MHV-permissive cell lines also showed activation of both p38 MAPK and JNK, which indicated that the MHV-induced stress-kinase activation was not restricted to any particular cell type. The upstream kinase responsible for activating MHV-induced p38 MAPK was the MAPK kinase 3. Experiments with a specific inhibitor of p38 MAPK, SB 203580, demonstrated that MHV-induced p38 MAPK activation resulted in the accumulation of interleukin-6 (IL-6) mRNAs and an increase in the production of IL-6, regardless of MHV-induced general host protein synthesis inhibition. Furthermore, MHV production was suppressed in SB 203580-treated cells, demonstrating that activated p38 MAPK played a role in MHV replication. The reduced MHV production in SB 203580-treated cells was, at least in part, due to a decrease in virus-specific protein synthesis and virus-specific mRNA accumulation. Interestingly, there was a transient increase in the amount of phosphorylation of the translation initiation factor 4E (eIF4E) in infected cells, and this eIF4E phosphorylation was p38 MAPK dependent; it is known that phosphorylated eIF4E enhances translation rates of cap-containing mRNAs. Furthermore, the upstream kinase responsible for eIF4E phosphorylation, MAPK-interacting kinase 1, was also phosphorylated and activated in response to MHV infection. Our data suggested that host cells, in response to MHV replication, activated p38 MAPK, which subsequently phosphorylated eIF4E to efficiently translate certain host proteins, including IL-6, during virus-induced severe host protein synthesis inhibition. MHV utilized this p38 MAPK-dependent increase in eIF4E phosphorylation to promote virus-specific protein synthesis and subsequent progeny virus production. Enhancement of virus-specific protein synthesis through virus-induced eIF4E activation has not been reported in any other viruses.
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Affiliation(s)
- Sangeeta Banerjee
- Department of Microbiology and Immunology, The University of Texas Medical Branch at Galveston, Galveston, Texas 77555-1019, USA
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