scholarly journals Downregulation of IRF-3 Levels by Ribozyme Modulates the Profile of IFNA Subtypes Expressed in Infected Human Cells

2001 ◽  
Vol 75 (6) ◽  
pp. 3021-3027 ◽  
Author(s):  
Wen-Shuz Yeow ◽  
Wei-Chun Au ◽  
William J. Lowther ◽  
Paula M. Pitha
Keyword(s):  
Viral Infection ◽  
Early Response ◽  
Human Cells ◽  
Transcriptional Level ◽  
Critical Determinant ◽  
Cellular Genes ◽  
Infected Cells ◽  
Alpha Beta ◽  
The Individual

ABSTRACT As an early response to viral infection, cells express a number of cellular genes that play a role in innate immunity, including alpha/beta interferons (IFN). IFN-α/β are encoded by a single IFNB gene and multiple, closely related IFNA genes. The induction of these IFN genes in infected cells occurs at the transcriptional level, and two transcription factors of the IRF family, IRF-3 and IRF-7, were shown to play a role in their activation. While the expression of IRF-3 alone was shown to be sufficient for induction of the IFNB gene, induction of all the IFNA subtypes in human cells required the presence of IRF-7. Since IRF-3 is expressed constitutively in all cells examined, the role of IRF-3 in the induction of IFNA genes has not been clarified. Using ribozyme targeted to IRF-3 mRNA, we found that the downregulation of IRF-3 levels in the infected cells inhibited not only the induction of IFNB gene but also the expression of IFNA genes. Furthermore, downmodulation of IRF-3 levels altered the expression profile of IFNA subtypes induced by viral infection. These studies suggest that the ratio between the relative levels of IRF-3 and IRF-7 is a critical determinant for the induction of the individual IFNA subtypes in infected cells.

scholarly journals Human IFITM3 restricts Chikungunya virus and Mayaro virus infection and is susceptible to virus-mediated counteraction

2020 ◽  
Author(s):  
Sergej Franz ◽  
Thomas Zillinger ◽  
Fabian Pott ◽  
Christiane Schüler ◽  
Sandra Dapa ◽  
...  
Keyword(s):  
Virus Infection ◽  
Influenza A ◽  
Chikungunya Virus ◽  
Protein S ◽  
Human Cells ◽  
Structural Protein ◽  
Infected Cells ◽  
Mayaro Virus ◽  
The Impact

AbstractInterferon-induced transmembrane (IFITM) proteins restrict infection by enveloped viruses through interfering with membrane fusion and virion internalisation. The role of IFITM proteins during alphaviral infection of human cells and viral counteraction strategies remain largely unexplored. Here, we characterized the impact of IFITM proteins and variants on entry and spread of Chikungunya virus (CHIKV) and Mayaro virus (MAYV) in human cells, and provide first evidence for a CHIKV-mediated antagonism of IFITM proteins. IFITM1, 2 and 3 restricted infection at the level of alphavirus glycoprotein-mediated entry, both in the context of direct infection and during cell-to-cell transmission. Relocalization of normally endosomal IFITM3 to the plasma membrane resulted in the loss of its antiviral activity. rs12252-C, a naturally occurring variant of IFITM3 that has been proposed to associate with severe influenza in humans, restricted CHIKV, MAYV and influenza A virus infection as efficiently as wild-type IFITM3. Finally, all antivirally active IFITM variants displayed reduced cell surface levels in CHIKV-infected cells involving a posttranscriptional process mediated by one or several non-structural protein(s) of CHIKV.

scholarly journals Role of glycosylation in the expression of human procathepsin D

1995 ◽  
Vol 108 (5) ◽  
pp. 2001-2006 ◽  
Author(s):  
S.C. Fortenberry ◽  
J.S. Schorey ◽  
J.M. Chirgwin
Keyword(s):  
Mammalian Cells ◽  
Human Cells ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Glycosylation Sites ◽  
Endogenous Protein ◽  
Lysosomal Targeting ◽  
The Individual

Human procathepsin D carries two N-linked glycosylation sites at asparagine residues 70 and 199, widely separated on the surface of the folded protein. We created monoglycosylated procathepsin D molecules by site-directed mutagenesis in vitro of the individual glycosylation sites. With only two exceptions, all 12 mutants of this type were expressed efficiently in mammalian cells. The expressed proteins were stable, targeted to the lysosome, and partially secreted into the medium. When both glycosylation sites were eliminated, however, the expressed proteins (9 different mutants) were stable but most were not secreted and targeted poorly to the lysosome. Mammalian fibroblasts appear to sort nascent procathepsin D efficiently only if it is N-glycosylated. Procathepsin D monoglycosylated at N70 is readily distinguished from the endogenous protein in transfected human cells and thus provides an excellent substrate for studying lysosomal targeting in an homologous system.

scholarly journals N6-methyladenosine of HIV-1 RNA regulates viral infection and HIV-1 Gag protein expression

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Nagaraja Tirumuru ◽  
Boxuan Simen Zhao ◽  
Wuxun Lu ◽  
Zhike Lu ◽  
Chuan He ◽  
...  
Keyword(s):  
Protein Expression ◽  
Viral Infection ◽  
Binding Sites ◽  
Domain Family ◽  
Gag Protein ◽  
Nuclear Rna ◽  
Infected Cells ◽  
Hiv 1 ◽  
In Cells

The internal N6-methyladenosine (m6A) methylation of eukaryotic nuclear RNA controls post-transcriptional gene expression, which is regulated by methyltransferases (writers), demethylases (erasers), and m6A-binding proteins (readers) in cells. The YTH domain family proteins (YTHDF1–3) bind to m6A-modified cellular RNAs and affect RNA metabolism and processing. Here, we show that YTHDF1–3 proteins recognize m6A-modified HIV-1 RNA and inhibit HIV-1 infection in cell lines and primary CD4+ T-cells. We further mapped the YTHDF1–3 binding sites in HIV-1 RNA from infected cells. We found that the overexpression of YTHDF proteins in cells inhibited HIV-1 infection mainly by decreasing HIV-1 reverse transcription, while knockdown of YTHDF1–3 in cells had the opposite effects. Moreover, silencing the m6A writers decreased HIV-1 Gag protein expression in virus-producing cells, while silencing the m6A erasers increased Gag expression. Our findings suggest an important role of m6A modification of HIV-1 RNA in viral infection and HIV-1 protein synthesis.

scholarly journals The Role of Extracellular Vesicles in Viral Infection and Transmission

Vaccines ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 102 ◽  
Author(s):  
Lorena Urbanelli ◽  
Sandra Buratta ◽  
Brunella Tancini ◽  
Krizia Sagini ◽  
Federica Delo ◽  
...  
Keyword(s):  
Immune Responses ◽  
Viral Infection ◽  
Extracellular Vesicles ◽  
Secretory Pathway ◽  
Cell Entry ◽  
Host Factors ◽  
Intercellular Signaling ◽  
Viral Pathogens ◽  
Infected Cells

Extracellular vesicles (EVs) have been found to be released by any type of cell and can be retrieved in every circulating body fluid, namely blood (plasma, serum), saliva, milk, and urine. EVs were initially considered a cellular garbage disposal tool, but later it became evident that they are involved in intercellular signaling. There is evidence that viruses can use EV endocytic routes to enter uninfected cells and hijack the EV secretory pathway to exit infected cells, thus illustrating that EVs and viruses share common cell entry and biogenesis mechanisms. Moreover, EVs play a role in immune response against viral pathogens. EVs incorporate and spread both viral and host factors, thereby prompting or inhibiting immune responses towards them via a multiplicity of mechanisms. The involvement of EVs in immune responses, and their potential use as agents modulating viral infection, will be examined. Although further studies are needed, the engineering of EVs could package viral elements or host factors selected for their immunostimulatory properties, to be used as vaccines or tolerogenic tools in autoimmune diseases.

scholarly journals Extreme heterogeneity of influenza virus infection in single cells

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Alistair B Russell ◽  
Cole Trapnell ◽  
Jesse D Bloom
Keyword(s):  
Influenza Virus ◽  
Virus Infection ◽  
Viral Infection ◽  
Single Cells ◽  
Influenza Virus Infection ◽  
Viral Gene ◽  
Viral Mrnas ◽  
Cellular Genes ◽  
Infected Cells ◽  
Cell Variation

Viral infection can dramatically alter a cell’s transcriptome. However, these changes have mostly been studied by bulk measurements on many cells. Here we use single-cell mRNA sequencing to examine the transcriptional consequences of influenza virus infection. We find extremely wide cell-to-cell variation in the productivity of viral transcription – viral transcripts comprise less than a percent of total mRNA in many infected cells, but a few cells derive over half their mRNA from virus. Some infected cells fail to express at least one viral gene, but this gene absence only partially explains variation in viral transcriptional load. Despite variation in viral load, the relative abundances of viral mRNAs are fairly consistent across infected cells. Activation of innate immune pathways is rare, but some cellular genes co-vary in abundance with the amount of viral mRNA. Overall, our results highlight the complexity of viral infection at the level of single cells.

Role of early stress in the individual differences in host response to viral infection

2006 ◽  
Vol 20 (4) ◽  
pp. 339-348 ◽  
Author(s):  
Ronit Avitsur ◽  
John Hunzeker ◽  
John F. Sheridan
Keyword(s):  
Individual Differences ◽  
Viral Infection ◽  
Host Response ◽  
Early Stress ◽  
The Individual

scholarly journals No evidence for basigin/CD147 as a direct SARS-CoV-2 spike binding receptor

2020 ◽  
Author(s):  
Jarrod Shilts ◽  
Gavin J. Wright
Keyword(s):  
Clinical Trial ◽  
Viral Infection ◽  
Protein Interaction ◽  
Human Cells ◽  
Spike Protein ◽  
Receptor Interactions ◽  
Direct Binding ◽  
Entry Receptor ◽  
Putative Mechanism

AbstractThe spike protein of SARS-CoV-2 is known to enable viral invasion into human cells through direct binding to host receptors including ACE2. An alternate entry receptor for the virus was recently proposed to be basigin/CD147. These early studies have already prompted a clinical trial and multiple published hypotheses of the role of this host receptor in viral infection and pathogenesis. We sought to independently characterize the basigin-spike protein interaction. After conducting several lines of experiments, we report that we are unable to find evidence supporting the role of basigin as a putative spike-binding receptor. Recombinant forms of both the entire ectodomain and S1 domain of the SARS-CoV-2 spike protein that directly bind ACE2 do not interact with basigin expressed on the surface of human cells. Using specialized assays tailored to detect receptor interactions as weak or weaker than the proposed basigin-spike binding, we report no evidence for direct binding of the viral spike to either of the two common isoforms of basigin. Given the pressing need for clarity on which targets of SARS-CoV-2 may lead to promising therapeutics, we present these findings to allow more informed decisions about the translational relevance of this putative mechanism in the race to understand and treat COVID-19.

The Role of Perspective in Defining Economic Measures for the Evaluation of Medical Technology

1996 ◽  
Vol 12 (1) ◽  
pp. 9-21 ◽  
Author(s):  
Amy J. Davidoff ◽  
Neil R. Powe
Keyword(s):  
Economic Analysis ◽  
Technology Assessment ◽  
Policy Making ◽  
Time Horizon ◽  
Medical Technology ◽  
Economic Cost ◽  
Critical Determinant ◽  
Society Perspective ◽  
The Individual

AbstractPerspectives in an economic analysis of medical technology reflect who makes decisions about the use of or payment for medical resources. Commonly used perspectives include those of providers, insurers, the individual, and society. Perspective is a critical determinant of study design, affecting the time horizon, types of resources considered, and economic cost measures assigned to those resources. Individuals involved in technology assessment for either research or policy-making purposes should be aware of the complexities of defining costs from different perspectives.

scholarly journals Induction of Cellular Genes Is Mediated by the Bel1 Transactivator in Foamy Virus-Infected Human Cells

2000 ◽  
Vol 74 (10) ◽  
pp. 4441-4447 ◽  
Author(s):  
Andrea Wagner ◽  
Anja Doerks ◽  
Mordechai Aboud ◽  
Angel Alonso ◽  
Takashi Tokino ◽  
...  
Keyword(s):  
Expression Profiles ◽  
Foamy Virus ◽  
Cdna Array ◽  
Human Cells ◽  
Cellular Gene ◽  
Cellular Genes ◽  
Factor Ii ◽  
Infected Cells ◽  
Necessary And Sufficient ◽  
Insight Into

ABSTRACT To gain insight into human foamy virus (HFV; also called spumaretrovirus)-induced alterations of cellular genes, the expression profiles of defined genes in HFV-infected primary human cells were analyzed by cDNA array assays. Several distinct cellular genes activated by HFV infection were identified; the identities of the cellular genes were confirmed by RNA blot analyses. Compared with mock-infected controls, the concentrations of cellular Kip2, Egr-1, COUP-TF1, insulin-like growth factor II (IGF-II), and EphB3 mRNAs were significantly increased in HFV-infected cells and showed a gene-specific and time-dependent induction. Immunoblot analyses with antibodies against some of the cellular gene products revealed increased levels of the corresponding proteins. To investigate mechanisms of HFV-induced alterations in cellular gene expression, the capacity of known HFV genes to increase expression of defined cellular genes was analyzed by transient expression experiments. Plasmids that encode the HFV Bel1 transcriptional transactivator were necessary and sufficient to strongly increase expression of p57Kip2, IGF-II, and EphB3 genes in 293T cells. Potential mechanisms and consequences of activation of cellular genes during HFV infection and Bel1 transactivation of the Kip2 gene are discussed.

scholarly journals Impacts of p97 on Proteome Changes in Human Cells during Coronaviral Replication

Cells ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2953
Author(s):  
Kai-Wen Cheng ◽  
Shan Li ◽  
Feng Wang ◽  
Nallely M. Ruiz-Lopez ◽  
Nadia Houerbi ◽  
...  
Keyword(s):  
Human Cells ◽  
Host Protein ◽  
Host Responses ◽  
Cytopathic Effects ◽  
Virus Life Cycle ◽  
Infected Cells ◽  
Infection Inhibition ◽  
Proteome Changes ◽  
Human Lung Cell Line

Human coronavirus (HCoV) similar to other viruses rely on host cell machinery for both replication and to spread. The p97/VCP ATPase is associated with diverse pathways that may favor HCoV replication. In this study, we assessed the role of p97 and associated host responses in human lung cell line H1299 after HCoV-229E or HCoV-OC43 infection. Inhibition of p97 function by small molecule inhibitors shows antiviral activity, particularly at early stages of the virus life cycle, during virus uncoating and viral RNA replication. Importantly, p97 activity inhibition protects human cells against HCoV-induced cytopathic effects. The p97 knockdown also inhibits viral production in infected cells. Unbiased quantitative proteomics analyses reveal that HCoV-OC43 infection resulted in proteome changes enriched in cellular senescence and DNA repair during virus replication. Further analysis of protein changes between infected cells with control and p97 shRNA identifies cell cycle pathways for both HCoV-229E and HCoV-OC43 infection. Together, our data indicate a role for the essential host protein p97 in supporting HCoV replication, suggesting that p97 is a therapeutic target to treat HCoV infection.

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