scholarly journals Guanidine Hydrochloride Inhibits Mammalian Orthoreovirus Growth by Reversibly Blocking the Synthesis of Double-Stranded RNA

2007 ◽  
Vol 81 (9) ◽  
pp. 4572-4584 ◽  
Author(s):  
Kenneth E. Murray ◽  
Max L. Nibert
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Rna Synthesis ◽  
Guanidine Hydrochloride ◽  
Mrna Translation ◽  
Specific Inhibition ◽  
Double Stranded Rna ◽  
Positive Sense ◽  
Mammalian Orthoreovirus ◽  
Negative Sense

ABSTRACT Millimolar concentrations of guanidine hydrochloride (GuHCl) are known to inhibit the replication of many plant and animal viruses having positive-sense RNA genomes. For example, GuHCl reversibly interacts with the nucleotide-binding region of poliovirus protein 2CATPase, resulting in a specific inhibition of viral negative-sense RNA synthesis. The use of GuHCl thereby allows for the spatiotemporal separation of poliovirus gene expression and RNA replication and provides a powerful tool to synchronize the initiation of negative-sense RNA synthesis during in vitro replication reactions. In the present study, we examined the effect of GuHCl on mammalian orthoreovirus (MRV), a double-stranded RNA (dsRNA) virus from the family Reoviridae. MRV growth in murine L929 cells was reversibly inhibited by 15 mM GuHCl. Furthermore, 15 mM GuHCl provided specific inhibition of viral dsRNA synthesis while sparing both positive-sense RNA synthesis and viral mRNA translation. By using GuHCl to provide temporal separation of MRV gene expression and genome replication, we obtained evidence that MRV primary transcripts support sufficient protein synthesis to assemble morphologically normal viral factories containing functional replicase complexes. In addition, the coordinated use of GuHCl and cycloheximide allowed us to demonstrate that MRV dsRNA synthesis can occur in the absence of ongoing protein synthesis, although to only a limited extent. Future studies utilizing the reversible inhibition of MRV dsRNA synthesis will focus on elucidating the target of GuHCl, as well as the components of the MRV replicase complexes.

Gene Expression Profiling of Hyperdiploid Multiple Reveal Complex Gene Dosage Effects and an mRNA Translation/Protein Synthesis Signature.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1538-1538
Author(s):  
Wee-Joo Chng ◽  
Scott Van Wier ◽  
Gregory Ahmann ◽  
Tammy Price-Troska ◽  
Kim Henderson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Differentially Expressed Genes ◽  
Gene Dosage ◽  
Gene Copy Number ◽  
Mrna Translation ◽  
Differentially Expressed ◽  
Gene Copy ◽  
Gene Dosage Effect ◽  
Expression Of Genes

Abstract Hyperdiploid MM (H-MM), characterized by recurrent trisomies constitute about 50% of MM, yet very little is known about its pathogenesis and oncogenic mechanisms. Studies in leukemia and solid tumors have shown gene dosage effect of aneuploidy on gene expression. To determine the possible gene dosage effect and deregulated cellular program in H-MM we undertook a gene expression study of CD138-enriched plasma-cell RNA from 53 hyperdiploid and 37 non-hyperdiploid MM (NH-MM) patients using the Affymetrix U133A chip (Affymetrix, Santa Clara, CA). Gene expression data was analyzed using GeneSpring 7 (Agilent Technologies, Palo Alto, CA). Genes differentially expressed between H-MM and NH-MM were obtained by t-test (p<0.01). The majority of the differentially expressed genes (57%) were under-expressed in H-MM. Genes located on the commonly trisomic chromosomes were mostly (but not always) over-expressed in H-MM and constitute 76% of over-expressed genes. Chromosome 1 contained the most differentially expressed genes (17%) followed by chromosome 12 (9%), and 19 (8%). To examine the relationship of gene copy number to gene expression, we examined the expression of genes on chromosomes 9 and 15 in subjects with 2 copies (15 normal control and 20 NH-MM) and 3 copies (12 H-MM) of each chromosome as detected by interphase FISH. We then derived a ratio of the mean expression of each gene on these chromosomes between patients with 3 copies and 2 copies of the chromosome. If a simple relationship exists between gene expression and gene copy number, one would expect the ratio of expression of most genes on these two chromosomes to be about 1.5 in H-MM compared to NH-MM. However, many genes have ratios either higher than 2 or lower than 0.5. Furthermore, when the heterogeneity of cells with underlying trisomies is taken into consideration by correcting the ratio for the number of cells with trisomies, the actual ratio is always lower than the expected ratio. When the expression of genes on a chromosome was compressed to a median value, this value was always higher in the trisomic chromosomes for H-MM compared to NH-MM. The data suggests that although gene dosage influence gene expression, the relationship is complex and some genes are more gene dosage dependent than others. Amongst the differentially expressed genes with known function, 33% are involved in mRNA translation/protein synthesis. Of note, 37 of the top 100 differentially expressed genes are involved in these processes. In particular, 60 ribosomal protein (RP) genes are significantly (p<0.05) upregulated in H-MM. This signature in H-MM is not associated with increase proliferation as measured by PCLI. This predominant signature suggests that deregulated protein synthesis may be important for the biology of H-MM. Many of these RPs are involved in the synthesis of product of oncogenic pathways (e.g. MYC, NF-KB pathways) and may mediate the growth and survival of tumor cells. It is therefore possible that these tumor cells may be sensitive to the disruption of mRNA translation/protein synthesis. Targeting the mTOR pathway with rapamycin may therefore be useful for treatment of H-MM.

scholarly journals Specific inhibition of HIV-1 gene expression by double-stranded RNA

2001 ◽  
Vol 1 (1) ◽  
pp. 219-220 ◽  
Author(s):  
W.-S. Park ◽  
N. Miyano-Kurosaki ◽  
E. Nakajima ◽  
H. Takaku
Keyword(s):  
Gene Expression ◽  
Specific Inhibition ◽  
Double Stranded Rna ◽  
Hiv 1

scholarly journals Role of Mitochondrial Membrane Spherules in Flock House Virus Replication

2016 ◽  
Vol 90 (7) ◽  
pp. 3676-3683 ◽  
Author(s):  
James R. Short ◽  
Jeffrey A. Speir ◽  
Radhika Gopal ◽  
Logan M. Pankratz ◽  
Jason Lanman ◽  
...  
Keyword(s):  
Host Defense ◽  
Rna Synthesis ◽  
Molecular Mechanisms ◽  
Rna Viruses ◽  
Rna Replication ◽  
Viral Rna ◽  
Flock House Virus ◽  
Double Stranded Rna ◽  
Content Type ◽  
Positive Sense

ABSTRACTViruses that generate double-stranded RNA (dsRNA) during replication must overcome host defense systems designed to detect this infection intermediate. All positive-sense RNA viruses studied to date modify host membranes to help facilitate the sequestration of dsRNA from host defenses and concentrate replication factors to enhance RNA production. Flock House virus (FHV) is an attractive model for the study of these processes since it is well characterized and infectsDrosophilacells, which are known to have a highly effective RNA silencing system. During infection, FHV modifies the outer membrane of host mitochondria to form numerous membrane invaginations, called spherules, that are ∼50 nm in diameter and known to be the site of viral RNA replication. While previous studies have outlined basic structural features of these invaginations, very little is known about the mechanism underlying their formation. Here we describe the optimization of an experimental system for the analysis of FHV host membrane modifications using crude mitochondrial preparations from infectedDrosophilacells. These preparations can be programmed to synthesize both single- and double-stranded FHV RNA. The system was used to demonstrate that dsRNA is protected from nuclease digestion by virus-induced membrane invaginations and that spherules play an important role in stimulating RNA replication. Finally, we show that spherules generated during FHV infection appear to be dynamic as evidenced by their ability to form or disperse based on the presence or absence of RNA synthesis.IMPORTANCEIt is well established that positive-sense RNA viruses induce significant membrane rearrangements in infected cells. However, the molecular mechanisms underlying these rearrangements, particularly membrane invagination and spherule formation, remain essentially unknown. How the formation of spherules enhances viral RNA synthesis is also not understood, although it is assumed to be partly a result of evading host defense pathways. To help interrogate some of these issues, we optimized a cell-free replication system consisting of mitochondria isolated from Flock House virus-infectedDrosophilacells for use in biochemical and structural studies. Our data suggest that spherules generated during Flock House virus replication are dynamic, protect double-stranded RNA, and enhance RNA replication in general. Cryo-electron microscopy suggests that the samples are amenable to detailed structural analyses of spherules engaged in RNA synthesis. This system thus provides a foundation for understanding the molecular mechanisms underlying spherule formation, maintenance, and function during positive-sense viral RNA replication.

Translational control by influenza virus: suppression of the kinase that phosphorylates the alpha subunit of initiation factor eIF-2 and selective translation of influenza viral mRNAs

1986 ◽  
Vol 6 (5) ◽  
pp. 1741-1750
Author(s):  
M G Katze ◽  
B M Detjen ◽  
B Safer ◽  
R M Krug
Keyword(s):  
Protein Synthesis ◽  
Influenza Virus ◽  
Mrna Translation ◽  
Initiation Factor ◽  
Alpha Subunit ◽  
Viral Mrna ◽  
Viral Mrnas ◽  
Double Stranded Rna ◽  
Selective Translation ◽  
Infected Cells

Selective translation of influenza viral mRNAs occurs after influenza virus superinfection of cells infected with the VAI RNA-negative adenovirus mutant dl331 (M. G. Katze, Y.-T. Chen, and R. M. Krug, Cell 37:483-490, 1984). Cell extracts from these doubly infected cells catalyze the initiation of essentially only influenza viral protein synthesis, reproducing the in vivo situation. This selective translation is correlated with a 5- to 10-fold suppression of the dl331-induced kinase that phosphorylates the alpha subunit of eucaryotic initiation factor eIF-2. This strongly suggests that influenza virus encodes a gene product that, analogous to the adenoviral VAI RNA, prevents the shutdown of overall protein synthesis caused by an eIF-2 alpha kinase turned on by viral infection. Adenoviral mRNA translation was restored to the extract from the doubly infected cells by the addition of the guanine nucleotide exchange factor eIF-2B, which is responsible for the normal recycling of eIF-2 during protein synthesis. This indicates that the residual kinase in the doubly infected cells leads to a limitation in functional (nonsequestered) eIF-2B and hence functional (GTP-containing) eIF-2 and that under these conditions influenza viral mRNAs are selectively translated over adenoviral mRNAs. Addition of double-stranded RNA to the extracts from these cells restored the eIF-2 alpha kinase to a level approaching that seen in extracts from cells infected with dl331 alone and caused the inhibition of influenza viral mRNA translation. This suggests that the putative influenza viral gene product acts against the double-stranded RNA activation of the kinase and indicates that influenza viral mRNA translation is also linked to the level of functional eIF-2. Our results thus indicate that a limitation in functional eIF-2 which causes a nonspecific reduction in the rate of initiation of protein synthesis results in the preferential translation of the better mRNAs (influenza viral mRNAs) at the expense of the poorer mRNAs (adenoviral mRNAs).

scholarly journals Coronavirus endoribonuclease targets viral polyuridine sequences to evade activating host sensors

2020 ◽  
Vol 117 (14) ◽  
pp. 8094-8103 ◽  
Author(s):  
Matthew Hackbart ◽  
Xufang Deng ◽  
Susan C. Baker
Keyword(s):  
Rna Synthesis ◽  
Therapeutic Interventions ◽  
Interferon Response ◽  
Wild Type ◽  
Molecular Pattern ◽  
Positive Sense ◽  
Infected Cells ◽  
Pathogen Associated Molecular Pattern ◽  
Negative Sense ◽  
Recognition Receptor

Coronaviruses (CoVs) are positive-sense RNA viruses that can emerge from endemic reservoirs and infect zoonotically, causing significant morbidity and mortality. CoVs encode an endoribonuclease designated EndoU that facilitates evasion of host pattern recognition receptor MDA5, but the target of EndoU activity was not known. Here, we report that EndoU cleaves the 5′-polyuridines from negative-sense viral RNA, termed PUN RNA, which is the product of polyA-templated RNA synthesis. Using a virus containing an EndoU catalytic-inactive mutation, we detected a higher abundance of PUN RNA in the cytoplasm compared to wild-type−infected cells. Furthermore, we found that transfecting PUN RNA into cells stimulates a robust, MDA5-dependent interferon response, and that removal of the polyuridine extension on the RNA dampens the response. Overall, the results of this study reveal the PUN RNA to be a CoV MDA5-dependent pathogen-associated molecular pattern (PAMP). We also establish a mechanism for EndoU activity to cleave and limit the accumulation of this PAMP. Since EndoU activity is highly conserved in all CoVs, inhibiting this activity may serve as an approach for therapeutic interventions against existing and emerging CoV infections.

scholarly journals Functional Characterization of the m6A-Dependent Translational Modulator PfYTH.2 in the Human Malaria Parasite

mBio ◽  
2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Ameya Sinha ◽  
Sebastian Baumgarten ◽  
Amy Distiller ◽  
Emma McHugh ◽  
Patty Chen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Plasmodium Falciparum ◽  
Protein Synthesis ◽  
Malaria Parasite ◽  
Binding Proteins ◽  
Functional Characterization ◽  
Mrna Translation ◽  
Content Type ◽  
Mrna Transcripts

ABSTRACT Posttranscriptional regulation of gene expression is central to the development and replication of the malaria parasite, Plasmodium falciparum, within its human host. The timely coordination of RNA maturation, homeostasis, and protein synthesis relies on the recruitment of specific RNA-binding proteins to their cognate target mRNAs. One possible mediator of such mRNA-protein interactions is the N6-methylation of adenosines (m6A), a prevalent mRNA modification of parasite mRNA transcripts. Here, we used RNA protein pulldowns, RNA modification mass spectrometry, and quantitative proteomics to identify two P. falciparum YTH domain proteins (PfYTH.1 and PfYTH.2) as m6A-binding proteins during parasite blood-stage development. Interaction proteomics revealed that PfYTH.2 associates with the translation machinery, including multiple subunits of the eukaryotic initiation factor 3 (eIF3) and poly(A)-binding proteins. Furthermore, knock sideways of PfYTH.2 coupled with ribosome profiling showed that this m6A reader is essential for parasite survival and is a repressor of mRNA translation. Together, these data reveal an important missing link in the m6A-mediated mechanism controlling mRNA translation in a unicellular eukaryotic pathogen. IMPORTANCE Infection with the unicellular eukaryotic pathogen Plasmodium falciparum causes malaria, a mosquito-borne disease affecting more than 200 million and killing 400,000 people each year. Underlying the asexual replication within human red blood cells is a tight regulatory network of gene expression and protein synthesis. A widespread mechanism of posttranscriptional gene regulation is the chemical modification of adenosines (m6A), through which the fate of individual mRNA transcripts can be changed. Here, we report on the protein machinery that “reads” this modification and “translates” it into a functional outcome. We provide mechanistic insight into one m6A reader protein and show that it interacts with the translational machinery and acts as a repressor of mRNA translation. This m6A-mediated phenotype has not been described in other eukaryotes as yet, and the functional characterization of the m6A interactome will ultimately open new avenues to combat the disease.

scholarly journals Translational control by influenza virus: suppression of the kinase that phosphorylates the alpha subunit of initiation factor eIF-2 and selective translation of influenza viral mRNAs.

1986 ◽  
Vol 6 (5) ◽  
pp. 1741-1750 ◽  
Author(s):  
M G Katze ◽  
B M Detjen ◽  
B Safer ◽  
R M Krug
Keyword(s):  
Protein Synthesis ◽  
Influenza Virus ◽  
Mrna Translation ◽  
Initiation Factor ◽  
Alpha Subunit ◽  
Viral Mrna ◽  
Viral Mrnas ◽  
Double Stranded Rna ◽  
Selective Translation ◽  
Infected Cells

Selective translation of influenza viral mRNAs occurs after influenza virus superinfection of cells infected with the VAI RNA-negative adenovirus mutant dl331 (M. G. Katze, Y.-T. Chen, and R. M. Krug, Cell 37:483-490, 1984). Cell extracts from these doubly infected cells catalyze the initiation of essentially only influenza viral protein synthesis, reproducing the in vivo situation. This selective translation is correlated with a 5- to 10-fold suppression of the dl331-induced kinase that phosphorylates the alpha subunit of eucaryotic initiation factor eIF-2. This strongly suggests that influenza virus encodes a gene product that, analogous to the adenoviral VAI RNA, prevents the shutdown of overall protein synthesis caused by an eIF-2 alpha kinase turned on by viral infection. Adenoviral mRNA translation was restored to the extract from the doubly infected cells by the addition of the guanine nucleotide exchange factor eIF-2B, which is responsible for the normal recycling of eIF-2 during protein synthesis. This indicates that the residual kinase in the doubly infected cells leads to a limitation in functional (nonsequestered) eIF-2B and hence functional (GTP-containing) eIF-2 and that under these conditions influenza viral mRNAs are selectively translated over adenoviral mRNAs. Addition of double-stranded RNA to the extracts from these cells restored the eIF-2 alpha kinase to a level approaching that seen in extracts from cells infected with dl331 alone and caused the inhibition of influenza viral mRNA translation. This suggests that the putative influenza viral gene product acts against the double-stranded RNA activation of the kinase and indicates that influenza viral mRNA translation is also linked to the level of functional eIF-2. Our results thus indicate that a limitation in functional eIF-2 which causes a nonspecific reduction in the rate of initiation of protein synthesis results in the preferential translation of the better mRNAs (influenza viral mRNAs) at the expense of the poorer mRNAs (adenoviral mRNAs).

The cytoplasmic fate of mRNA

2001 ◽  
Vol 114 (10) ◽  
pp. 1797-1798
Author(s):  
L.C. Kuhn
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Translational Control ◽  
Rna World ◽  
Mrna Translation ◽  
Fine Tuning ◽  
Control Mechanisms ◽  
Control Of Gene Expression ◽  
Interaction Sites ◽  
Translation Apparatus

Translational Control of Gene Expression edited by N. Sonenberg, J. W. B. Hershey and M. B. Matthews Cold Spring Harbor Laboratory Press (2000) 1020 pages. ISBN 0–87969-568-4 US$115 At the beginning of the 90s most molecular biologists were focusing on transcription and RNA splicing. mRNA translation and its temporal and spatial regulation seemed research topics for insiders at that time. However, all aspects of mRNA fate in the cytoplasm will certainly attract much more attention during the next decade. The field is now flourishing with connections to all disciplines of biology. This book will help you to realize the tremendous variation of translational regulatory mechanisms existing in nature. The evidence for their importance has become so overwhelming that nobody seriously interested in gene expression can ignore it any longer. It is the great merit of the editors of this book that they have brought together an impressive series of first-class reviews written by the most prominent scientists in the field. The new monograph takes a fresh look at the field and is greatly expanded compared with the earlier 1996 version. The book is judiciously divided into two parts. The first part comprises eight broad chapters, giving an overview of the main principles of protein synthesis and its regulation. They serve as a thorough basis for the second part, which comprises twenty-eight chapters, each about 20 pages in length, that present in depth additional exciting areas in which there is strong research activity. Your appetite for this book will be stimulated right at the beginning by the wonderful introductory chapter, which is written jointly by the editors and defines the field in its entire complexity. Given that translation is of course a unifying principle of all living organisms, why are there such a large number of different control mechanisms modulating the use of mRNA templates and making actual protein level not predictable from RNA quantity alone? Are these just remnants of an RNA world or, as the authors seem to believe, effective adaptations for fine-tuning gene expression that have been opportunistically added during evolution? Five broad chapters are devoted to our knowledge of initiation, elongation and termination of translation both in eukaryotes and in prokaryotes. It is amazing how much detail has been added, in just the past five years, to our picture of the biochemistry, structure and function of ribosomes, initiation sites, and translation factors. However, translational control of gene expression is not just a matter of the translation machinery alone. It seems rather that the tremendously versatile mRNA sequences and structures impose the way they are seen by the translation apparatus and its factors. Particularly in eukaryotes, the untranslated parts of mRNAs play a decisive role by providing additional interaction sites for cytoplasmic proteins that modulate mRNA stability, mRNA localization or accessibility of mRNAs to translation. In turn, many of the proteins interacting with mRNA are themselves regulated by metabolites or post-translational modifications. This is beautifully documented in an exciting chapter on the role of translational control in developmental decisions. For example, in Drosophila, a specific cascade of factors acting on RNA localization and translation controls the anterior-posterior body axis. In C. elegans, the fate of germ-line cells is determined by translational repression. And you will find many more such examples. Another important section of the book is devoted to changes in translation that occur during virus infection. Again one is amazed by the variety of ways by which viruses divert the host translation apparatus for their own sake. The shorter chapters give insight into additional exciting areas in the field. For example, research into how heat shock or signal transduction pathways feed into translation, what we know about mRNA degradation of normal and nonsense-containing transcripts, and the evidence that local synaptic protein synthesis represents a molecular hallmark of learning and memory. This book is the most complete and up-to-date review of translational control mechanisms. It is a must for students entering the field, and it will constitute for many years a major reference guide for any investigator who is seriously interested in the full picture of gene expression.

scholarly journals Novel Mycoviruses Discovered in the Mycovirome of a Necrotrophic Fungus

mBio ◽  
2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Ana Ruiz-Padilla ◽  
Julio Rodríguez-Romero ◽  
Irene Gómez-Cid ◽  
Davide Pacifico ◽  
María A. Ayllón
Keyword(s):  
Chemical Control ◽  
Pathogenic Fungus ◽  
Pathogenic Fungi ◽  
General Knowledge ◽  
Double Stranded Rna ◽  
Positive Sense ◽  
Dsrna Genome ◽  
Horizontal Transfers ◽  
First Time ◽  
Negative Sense

ABSTRACT Botrytis cinerea is one of the most important plant-pathogenic fungus. Products based on microorganisms can be used in biocontrol strategies alternative to chemical control, and mycoviruses have been explored as putative biological agents in such approaches. Here, we have explored the mycovirome of B. cinerea isolates from grapevine of Italy and Spain to increase the knowledge about mycoviral diversity and evolution, and to search for new widely distributed mycoviruses that could be active ingredients in biological products to control this hazardous fungus. A total of 248 B. cinerea field isolates were used for our metatranscriptomic study. Ninety-two mycoviruses were identified: 62 new mycoviral species constituting putative novel viral genera and families. Of these mycoviruses, 57 had a positive-sense single-stranded RNA (ssRNA) genome, 19 contained a double-stranded RNA (dsRNA) genome, 15 had a negative-sense ssRNA genome, and 1 contained a single-stranded DNA (ssDNA) genome. In general, ssRNA mycoviruses were widely distributed in all sampled regions, the ssDNA mycovirus was more frequently found in Spain, and dsRNA mycoviruses were scattered in some pools of both countries. Some of the identified mycoviruses belong to clades that have never been found associated with Botrytis species: Botrytis-infecting narnaviruses; alpha-like, umbra-like, and tymo-like ssRNA+ mycoviruses; trisegmented ssRNA− mycovirus; bisegmented and tetrasegmented dsRNA mycoviruses; and finally, an ssDNA mycovirus. Among the results obtained in this massive mycovirus screening, the discovery of novel bisegmented viruses, phylogenetically related to narnaviruses, is remarkable. IMPORTANCE The results obtained here have expanded our knowledge of mycoviral diversity, horizontal transfers, and putative cross-kingdom events. To date, this study presents the most extensive and wide diversity collection of mycoviruses infecting the necrotrophic fungus B. cinerea. The collection included all types of mycoviruses, with dsRNA, ssRNA+, ssRNA–, and ssDNA genomes, most of which were discovered here, and some of which were previously reported as infecting B. cinerea or other plant-pathogenic fungi. Some of these mycoviruses are reported for the first time here associated with B. cinerea, as a trisegmented ssRNA– mycovirus and as an ssDNA mycovirus, but even more remarkablly, we also describe here four novel bisegmented viruses (binarnaviruses) not previously described in nature. The present findings significantly contribute to general knowledge in virology and more particularly in the field of mycovirology.

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