scholarly journals Adenovirus E4orf4 Protein Downregulates MYC Expression through Interaction with the PP2A-B55 Subunit

2008 ◽  
Vol 82 (19) ◽  
pp. 9381-9388 ◽  
Author(s):  
Haggit Ben-Israel ◽  
Rakefet Sharf ◽  
Gideon Rechavi ◽  
Tamar Kleinberger
Keyword(s):  
Rna Stability ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Transcriptional Elongation ◽  
Reading Frame ◽  
Temporal Regulation ◽  
Protein Levels ◽  
Viral Genes ◽  
Oligonucleotide Microarray Analysis ◽  
Adenovirus Replication

ABSTRACT The adenovirus E4 open reading frame 4 (E4orf4) protein is a multifunctional viral regulator that is involved in the temporal regulation of viral gene expression by modulating cellular and viral genes at the transcription and translation levels and by controlling alternative splicing of adenoviral late mRNAs. When expressed individually, E4orf4 induces apoptosis in transformed cells. Using oligonucleotide microarray analysis, validated by quantitative real time PCR, we found that MYC (also known as c-Myc) is downregulated early after the induction of E4orf4 expression. As a result, Myc protein levels are reduced in E4orf4-expressing cells. MYC downregulation is observed both when E4orf4 is expressed individually and within the context of viral infection. E4orf4 reduces MYC transcription but does not affect transcriptional elongation or RNA stability. An interaction with the PP2A-B55 subunit is required for the downregulation of MYC by E4orf4. Since Myc overexpression was previously shown to inhibit adenovirus replication, the downregulation of Myc by E4orf4 would contribute to efficient virus infection.

scholarly journals Genome Size and Structure Determine Efficiency of Postinternalization Steps and Gene Transfer of Capsid-Modified Adenovirus Vectors in a Cell-Type-Specific Manner

2004 ◽  
Vol 78 (18) ◽  
pp. 10009-10022 ◽  
Author(s):  
Dmitry M. Shayakhmetov ◽  
Zong-Yi Li ◽  
Anuj Gaggar ◽  
Helen Gharwan ◽  
Vladimir Ternovoi ◽  
...  
Keyword(s):  
Gene Transfer ◽  
Genome Size ◽  
First Generation ◽  
Viral Gene Expression ◽  
Protein Composition ◽  
Cell Types ◽  
Helper Virus ◽  
Viral Gene ◽  
Viral Genes ◽  
Size And Structure

ABSTRACT Adenovirus serotype 5 (Ad5) vectors containing Ad B-group fibers have become increasingly popular as gene transfer vectors because they efficiently transduce human cell types that are relatively refractory to Ad5 infection. So far, most B-group fiber-containing vectors have been first-generation vectors, deleted of E1 and/or E3 genes. Transduction with these vectors, however, results in viral gene expression and is associated with cytotoxicity and immune responses against transduced cells. To circumvent these problems, we developed fiber-chimeric Ad vectors devoid of all viral genes that were produced either by the homologous recombination of first-generation vectors or by using the Cre/lox-based helper virus system. In this study we compared early steps of infection between first-generation (35-kb genome) and Ad vectors devoid of all viral genes with genome sizes of 28 kb and 12.6 kb. All vectors possessed an Ad35-derived fiber knob domain, which uses CD46 as a primary attachment receptor. Using immortalized human hematopoietic cell lines and primary human CD34-positive hematopoietic cells, we found that the Ad genome size did not affect the efficiency of virus attachment to and internalization into cells. Furthermore, independently of the genome length and structure, all vectors migrated to the nucleus through late endosomal and lysosomal cellular compartments. However, the vector containing the short 12.6-kb genome was unable to efficiently escape from endosomes and deliver its DNA into the nucleus. Moreover, compared to other vectors, these Ad particles were less stable and had an abnormal capsid protein composition, including a lack of capsid-stabilizing protein IX. Our data indicate that the size and structure of the packaged viral genomes can affect the integrity of Ad particles, which in turn results in lower infectivity of Ad vectors.

scholarly journals Global Analysis of Baculovirus Autographa californica Multiple Nucleopolyhedrovirus Gene Expression in the Midgut of the Lepidopteran HostTrichoplusia ni

2018 ◽  
Vol 92 (23) ◽  
Author(s):  
Anita Shrestha ◽  
Kan Bao ◽  
Yun-Ru Chen ◽  
Wenbo Chen ◽  
Ping Wang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Line ◽  
Trichoplusia Ni ◽  
Cultured Cells ◽  
Expression Profiles ◽  
Secondary Infection ◽  
Expression Patterns ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Viral Genes

ABSTRACTThe baculovirusAutographa californica multiple nucleopolyhedrovirus(AcMNPV) is a large double-stranded DNA (dsDNA) virus that encodes approximately 156 genes and is highly pathogenic to a variety of larval lepidopteran insects in nature. Oral infection of larval midgut cells is initiated by the occlusion-derived virus (ODV), while secondary infection of other tissues is mediated by the budded virus (BV). Global viral gene expression has been studied in detail in BV-infected cell cultures, but studies of ODV infection in the larval midgut are limited. In this study, we examined expression of the ∼156 AcMNPV genes inTrichoplusia nimidgut tissue using a transcriptomic approach. We analyzed expression profiles of viral genes in the midgut and compared them with profiles from aT. nicell line (Tnms42). Several viral genes (p6.9,orf76,orf75,pp31,Ac-bro,odv-e25, andodv-ec27) had high expression levels in the midgut throughout the infection. Also, the expression of genes associated with occlusion bodies (polhandp10) appeared to be delayed in the midgut in comparison with the cell line. Comparisons of viral gene expression profiles revealed remarkable similarities between the midgut and cell line for most genes, although substantial differences were observed for some viral genes. These included genes associated with high level BV production (fp-25k), acceleration of systemic infection (v-fgf), and enhancement of viral movement (arif-1/orf20). These differential expression patterns appear to represent specific adaptations for virus infection and transmission through the polarized cells of the lepidopteran midgut.IMPORTANCEBaculoviruses such as AcMNPV are pathogens that are natural regulators of certain insect populations. Baculovirus infections are biphasic, with a primary phase initiated by oral infection of midgut epithelial cells by occlusion-derived virus (ODV) virions and a secondary phase in which other tissues are infected by budded-virus (BV) virions. While AcMNPV infections in cultured cells have been studied extensively, comparatively little is known regarding primary infection in the midgut. In these studies, we identified gene expression patterns associated with ODV-mediated infection of the midgut inTrichoplusia niand compared those results with prior results from BV-infected cultured cells, which simulate secondary infection. These studies provide a detailed analysis of viral gene expression patterns in the midgut, which likely represent specific viral strategies to (i) overcome or avoid host defenses in the gut and (ii) rapidly move infection from the midgut, into the hemocoel to facilitate systemic infection.

scholarly journals The Autoregulatory and Transactivating Functions of the Human Cytomegalovirus IE86 Protein Use Independent Mechanisms for Promoter Binding

2007 ◽  
Vol 81 (11) ◽  
pp. 5807-5818 ◽  
Author(s):  
Dustin T. Petrik ◽  
Kimberly P. Schmitt ◽  
Mark F. Stinski
Keyword(s):  
Human Cytomegalovirus ◽  
Protein Interactions ◽  
Chromatin Immunoprecipitation ◽  
Viral Gene Expression ◽  
Artificial Chromosome ◽  
Viral Gene ◽  
Chip Assay ◽  
Protein Protein Interactions ◽  
Multiple Sequence ◽  
Viral Genes

ABSTRACT The functions of the human cytomegalovirus (HCMV) IE86 protein are paradoxical, as it can both activate and repress viral gene expression through interaction with the promoter region. Although the mechanism for these functions is not clearly defined, it appears that a combination of direct DNA binding and protein-protein interactions is involved. Multiple sequence alignment of several HCMV IE86 homologs reveals that the amino acids 534LPIYE538 are conserved between all primate and nonprimate CMVs. In the context of a bacterial artificial chromosome (BAC), mutation of both P535 and Y537 to alanines (P535A/Y537A) results in a nonviable BAC. The defective HCMV BAC does not undergo DNA replication, although the P535A/Y537A mutant IE86 protein appears to be stably expressed. The P535A/Y537A mutant IE86 protein is able to negatively autoregulate transcription from the major immediate-early (MIE) promoter and was recruited to the MIE promoter in a chromatin immunoprecipitation (ChIP) assay. However, the P535A/Y537A mutant IE86 protein was unable to transactivate early viral genes and was not recruited to the early viral UL4 and UL112 promoters in a ChIP assay. From these data, we conclude that the transactivation and repressive functions of the HCMV IE86 protein can be separated and must occur through independent mechanisms.

scholarly journals Acetylation of cytidine residues boosts HIV-1 gene expression by increasing viral RNA stability

2020 ◽  
Author(s):  
Kevin Tsai ◽  
Ananda Ayyappan Jaguva Vasudevan ◽  
Cecilia Martinez Campos ◽  
Ann Emery ◽  
Ronald Swanstrom ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Stability ◽  
Antiviral Drug ◽  
Viral Gene Expression ◽  
Mrna Translation ◽  
Viral Gene ◽  
Viral Mrnas ◽  
Cellular Target ◽  
Covalent Modifications ◽  
Hiv 1

AbstractCovalent modifications added to individual nucleotides on mRNAs, called epitranscriptomic modifications, have recently emerged as key regulators of both cellular and viral mRNA function1,2 and RNA methylation has now been shown to enhance the replication of human immunodeficiency virus 1 (HIV-1) and several other viruses3–11. Recently, acetylation of the N4 position of cytidine (ac4C) was reported to boost cellular mRNA function by increasing mRNA translation and stability12. We therefore hypothesized that ac4C and N-acetyltransferase 10 (NAT10), the cellular enzyme that adds ac4C to RNAs, might also have been subverted by HIV-1 to increase viral gene expression. We now confirm that HIV-1 transcripts are indeed modified by addition of ac4C at multiple discreet sites and demonstrate that silent mutagenesis of a subset of these ac4C addition sites inhibits HIV-1 gene expression in cis. Moreover, reduced expression of NAT10, and the concomitant decrease in the level of ac4C on viral RNAs, inhibits HIV-1 replication by reducing HIV-1 RNA stability. Interestingly Remodelin, a previously reported inhibitor of NAT10 function13,14, also inhibits HIV-1 replication without affecting cell viability, thus raising the possibility that the addition of ac4C to viral mRNAs might emerge as a novel cellular target for antiviral drug development.

scholarly journals Expression of varicella-zoster virus VLT-ORF63 fusion transcript induces broad viral gene expression during reactivation from neuronal latency

2020 ◽  
Author(s):  
Werner J. D. Ouwendijk ◽  
Daniel P. Depledge ◽  
Labchan Rajbhandari ◽  
Tihana Lenac Rovis ◽  
Stipan Jonjic ◽  
...  
Keyword(s):  
Gene Expression ◽  
Varicella Zoster Virus ◽  
Viral Gene Expression ◽  
Fusion Transcript ◽  
Viral Gene ◽  
Reading Frame ◽  
Varicella Zoster ◽  
Rapid Amplification

SummaryVaricella-zoster virus (VZV) establishes lifelong neuronal latency in most humans world-wide, reactivating in one-third to cause herpes zoster and occasionally chronic pain. How VZV establishes, maintains and reactivates from latency is largely unknown. Latent VZV gene expression is restricted to VZV latency-associated transcript (VLT) and open reading frame 63 (ORF63) in naturally VZV-infected human trigeminal ganglia (TG). Notably, these transcript levels positively correlated suggesting co-regulated transcription during latency. Here, we used direct RNA-sequencing to identify fusion transcripts that combine VLT and ORF63 loci (VLT-ORF63) and are expressed during both lytic and latent VZV infections. Furthermore, real-time PCR, RNA in situ hybridization and 5’ rapid amplification of cDNA ends (RACE) all confirmed VLT-ORF63, but not canonical ORF63, expression in human TG. During lytic infection, one of the two major VLT-ORF63 isoforms encodes a novel fusion protein combining VLT and ORF63 proteins (pVLT-ORF63). In vitro, VLT is transcribed in latently VZV-infected human sensory neurons, whereas VLT-ORF63 expression is induced by reactivation stimuli. Moreover, the pVLT-ORF63-encoding VLT-ORF63 isoform induced transcription of lytic VZV genes. Collectively, our findings show that VZV expresses a unique set of VLT-ORF63 transcripts, potentially involved in the transition from latency to lytic VZV infection.

scholarly journals The Ends Dictate the Means: Promoter Switching in Herpesvirus Gene Expression

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Andrew E. Hale ◽  
Nathaniel J. Moorman
Keyword(s):  
Gene Expression ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Annual Review ◽  
Publication Date ◽  
Alternative Promoters ◽  
Contextual Cues ◽  
Viral Genes ◽  
Functional Consequences ◽  
Post Transcriptional Regulation

Herpesvirus gene expression is dynamic and complex, with distinct complements of viral genes expressed at specific times in different infection contexts. These complex patterns of viral gene expression arise in part from the integration of multiple cellular and viral signals that affect the transcription of viral genes. The use of alternative promoters provides an increased level of control, allowing different promoters to direct the transcription of the same gene in response to distinct temporal and contextual cues. While once considered rare, herpesvirus alternative promoter usage was recently found to be far more pervasive and impactful than previously thought. Here we review several examples of promoter switching in herpesviruses and discuss the functional consequences on the transcriptional and post-transcriptional regulation of viral gene expression. Expected final online publication date for the Annual Review of Virology, Volume 8 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals Mechanisms of pathogenesis of emerging adenoviruses

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 90 ◽  
Author(s):  
James Cook ◽  
Jay Radke
Keyword(s):  
Gene Expression ◽  
Human Population ◽  
Viral Gene Expression ◽  
Critical Threshold ◽  
Severe Illness ◽  
Viral Gene ◽  
Altered Expression ◽  
Biological Studies ◽  
Viral Genes

Periodic outbreaks of human adenovirus infections can cause severe illness in people with no known predisposing conditions. The reasons for this increased viral pathogenicity are uncertain. Adenoviruses are constantly undergoing mutation during circulation in the human population, but related phenotypic changes of the viruses are rarely detected because of the infrequency of such outbreaks and the limited biological studies of the emergent strains. Mutations and genetic recombinations have been identified in these new strains. However, the linkage between these genetic changes and increased pathogenicity is poorly understood. It has been observed recently that differences in virus-induced immunopathogenesis can be associated with altered expression of non-mutant viral genes associated with changes in viral modulation of the host innate immune response. Initial small animal studies indicate that these changes in viral gene expression can be associated with enhanced immunopathogenesisin vivo. Available evidence suggests the hypothesis that there is a critical threshold of expression of certain viral genes that determines both the sustainability of viral transmission in the human population and the enhancement of immunopathogenesis. Studies of this possibility will require extension of the analysis of outbreak viral strains from a sequencing-based focus to biological studies of relationships between viral gene expression and pathogenic responses. Advances in this area will require increased coordination among public health organizations, diagnostic microbiology laboratories, and research laboratories to identify, catalog, and systematically study differences between prototype and emergent viral strains that explain the increased pathogenicity that can occur during clinical outbreaks.

scholarly journals Genome-Wide Analysis of Heterogeneous Nuclear Ribonucleoprotein (hnRNP) Binding to HIV-1 RNA Reveals a Key Role for hnRNP H1 in Alternative Viral mRNA Splicing

2019 ◽  
Vol 93 (21) ◽  
Author(s):  
Sebla B. Kutluay ◽  
Ann Emery ◽  
Srinivasa R. Penumutchu ◽  
Dana Townsend ◽  
Kasyap Tenneti ◽  
...  
Keyword(s):  
Gene Expression ◽  
Alternative Splicing ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Hnrnp A1 ◽  
Viral Mrnas ◽  
Temporal Regulation ◽  
Coding Potential ◽  
Hiv 1

ABSTRACT Alternative splicing of HIV-1 mRNAs increases viral coding potential and controls the levels and timing of gene expression. HIV-1 splicing is regulated in part by heterogeneous nuclear ribonucleoproteins (hnRNPs) and their viral target sequences, which typically repress splicing when studied outside their native viral context. Here, we determined the location and extent of hnRNP binding to HIV-1 mRNAs and their impact on splicing in a native viral context. Notably, hnRNP A1, hnRNP A2, and hnRNP B1 bound to many dispersed sites across viral mRNAs. Conversely, hnRNP H1 bound to a few discrete purine-rich sequences, a finding that was mirrored in vitro. hnRNP H1 depletion and mutation of a prominent viral RNA hnRNP H1 binding site decreased the use of splice acceptor A1, causing a deficit in Vif expression and replicative fitness. This quantitative framework for determining the regulatory inputs governing alternative HIV-1 splicing revealed an unexpected splicing enhancer role for hnRNP H1 through binding to its target element. IMPORTANCE Alternative splicing of HIV-1 mRNAs is an essential yet quite poorly understood step of virus replication that enhances the coding potential of the viral genome and allows the temporal regulation of viral gene expression. Although HIV-1 constitutes an important model system for general studies of the regulation of alternative splicing, the inputs that determine the efficiency with which splice sites are utilized remain poorly defined. Our studies provide an experimental framework to study an essential step of HIV-1 replication more comprehensively and in much greater detail than was previously possible and reveal novel cis-acting elements regulating HIV-1 splicing.

scholarly journals Importance of codon usage for the temporal regulation of viral gene expression

2015 ◽  
Vol 112 (45) ◽  
pp. 14030-14035 ◽  
Author(s):  
Young C. Shin ◽  
Georg F. Bischof ◽  
William A. Lauer ◽  
Ronald C. Desrosiers
Keyword(s):  
Gene Expression ◽  
Rhesus Monkey ◽  
Codon Usage ◽  
Viral Gene Expression ◽  
Luciferase Reporter ◽  
Viral Gene ◽  
Gene Products ◽  
Temporal Regulation ◽  
Persistent Viruses ◽  
Late Expression

The glycoproteins of herpesviruses and of HIV/SIV are made late in the replication cycle and are derived from transcripts that use an unusual codon usage that is quite different from that of the host cell. Here we show that the actions of natural transinducers from these two different families of persistent viruses (Rev of SIV and ORF57 of the rhesus monkey rhadinovirus) are dependent on the nature of the skewed codon usage. In fact, the transinducibility of expression of these glycoproteins by Rev and by ORF57 can be flipped simply by changing the nature of the codon usage. Even expression of a luciferase reporter could be made Rev dependent or ORF57 dependent by distinctive changes to its codon usage. Our findings point to a new general principle in which different families of persisting viruses use a poor codon usage that is skewed in a distinctive way to temporally regulate late expression of structural gene products.

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