Interaction of influenza virus NS1 protein and the human homologue of Staufen in vivo and in vitro

Falcón, Ana; Fortes, Puri; Marión, Rosa M.; Beloso, Ana; Ortı́n, Juan

doi:10.1093/nar/27.11.2241

Cited by 82 publications

(88 citation statements)

References 46 publications

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“…Expression of neither DRBP76 (35) nor mammalian Staufen (66) prevented IRF7 phosphorylation, nor did they block the inhibitory action of E3L (Fig. 6C and data not shown), despite these proteins being implicated in regulation of PKR and viral infection (35,36,66). Additionally, E3L but not K3L effectively inhibited IRF3 phosphorylation following NDV infection (Fig.…”

Section: Irf7 Phosphorylation Is Blocked By Vaccinia Virus E3l Proteimentioning

confidence: 93%

IRF3 and IRF7 Phosphorylation in Virus-infected Cells Does Not Require Double-stranded RNA-dependent Protein Kinase R or IκB Kinase but Is Blocked by Vaccinia Virus E3L Protein

Smith

Marié

Prakash

et al. 2001

Journal of Biological Chemistry

219

164

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Induction of interferon-␣ (IFN␣) gene expression in virus-infected cells requires phosphorylation-induced activation of the transcription factors IRF3 and IRF7.However, the kinase(s) that targets these proteins has not been identified. Using a combined pharmacological and genetic approach, we found that none of the kinases tested was responsible for IRF phosphorylation in cells infected with Newcastle disease virus (NDV). Although the broad-spectrum kinase inhibitor staurosporine potently blocked IRF3 and -7 phosphorylation, inhibitors for protein kinase C, protein kinase A, MEK, SAPK, IKK, and protein kinase R (PKR) were without effect. Both IB kinase and PKR have been implicated in IFN induction, but cells genetically deficient in IB kinase, PKR, or the PKR-related genes PERK, IRE1, or GCN2 retained the ability to phosphorylate IRF7 and induce IFN␣. Interestingly, PKR mutant cells were defective for response to double-stranded (ds) RNA but not to virus infection, suggesting that dsRNA is not the only activating viral component. Consistent with this notion, protein synthesis was required for IRF7 phosphorylation in virus-infected cells, and the kinetics of phosphorylation and viral protein production were similar. Despite evidence for a lack of involvement of dsRNA and PKR, vaccinia virus E3L protein, a dsRNA-binding protein capable of inhibiting PKR, was an effective IRF3 and -7 phosphorylation inhibitor. These results suggest that a novel cellular protein that is activated by viral products in addition to dsRNA and is sensitive to E3L inhibition is responsible for IRF activation and reveal a novel mechanism for the anti-IFN effect of E3L distinct from its inhibition of PKR.

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Section: Irf7 Phosphorylation Is Blocked By Vaccinia Virus E3l Proteimentioning

confidence: 93%

IRF3 and IRF7 Phosphorylation in Virus-infected Cells Does Not Require Double-stranded RNA-dependent Protein Kinase R or IκB Kinase but Is Blocked by Vaccinia Virus E3L Protein

Smith

Marié

Prakash

et al. 2001

Journal of Biological Chemistry

219

164

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“…By this mechanism, the NS1 protein prevents IFN-␣/␤ synthesis, as well as activation of the antiviral enzyme PKR (23,148,233). It was also suggested that NS1 can inhibit PKR in a dsRNA-independent manner, by forming complexes between the NS1 protein and PKR (348), although direct interaction of NS1 and PKR remains controversial (95). It was recently shown that, through its cellular activator PACT, NS1 can prevent PKR activation (227).…”

Section: Orthomyxovirus: Influenza Virusmentioning

confidence: 99%

Impact of Protein Kinase PKR in Cell Biology: from Antiviral to Antiproliferative Action

García

Gil

Ventoso

et al. 2006

Microbiol Mol Biol Rev

694

731

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SUMMARY The double-stranded RNA-dependent protein kinase PKR is a critical mediator of the antiproliferative and antiviral effects exerted by interferons. Not only is PKR an effector molecule on the cellular response to double-stranded RNA, but it also integrates signals in response to Toll-like receptor activation, growth factors, and diverse cellular stresses. In this review, we provide a detailed picture on how signaling downstream of PKR unfolds and what are the ultimate consequences for the cell fate. PKR activation affects both transcription and translation. PKR phosphorylation of the alpha subunit of eukaryotic initiation factor 2 results in a blockade on translation initiation. However, PKR cannot avoid the translation of some cellular and viral mRNAs bearing special features in their 5′ untranslated regions. In addition, PKR affects diverse transcriptional factors such as interferon regulatory factor 1, STATs, p53, activating transcription factor 3, and NF-κB. In particular, how PKR triggers a cascade of events involving IKK phosphorylation of IκB and NF-κB nuclear translocation has been intensively studied. At the cellular and organism levels PKR exerts antiproliferative effects, and it is a key antiviral agent. A point of convergence in both effects is that PKR activation results in apoptosis induction. The extent and strength of the antiviral action of PKR are clearly understood by the findings that unrelated viral proteins of animal viruses have evolved to inhibit PKR action by using diverse strategies. The case for the pathological consequences of the antiproliferative action of PKR is less understood, but therapeutic strategies aimed at targeting PKR are beginning to offer promising results.

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“…It is translated from the colinear transcript of segment 8, which also encodes NS2 protein from a spliced mRNA (31, 34). NS1 accumulates in the nucleus early in the infection (4, 32) and when it is expressed from cDNA (26,35,56), but at late times in the infection it is also found in the cytoplasm (49), in association with polysomes (8,16,32).Although NS1 protein is apparently nonessential, as a recombinant virus has been generated that lacks the gene (23), several virus mutants have been isolated or generated which contain mutations in the NS1 protein and are severely hampered for replication (12,14,17,27,28,40,60,(63)(64)(65). The phenotypes of these mutant viruses indicate that NS1 protein may be involved in several steps in the virus infectious cycle, including transcription and/or replication of virus RNA, late virus protein synthesis, and interference with the cellular gene expression, and that it eventually modulates the virulence of virus infections in vivo (2, 23, 68).…”

mentioning

confidence: 99%

mentioning

confidence: 99%

“…These include the virus RNP and/or polymerase (45), cellular proteins involved in translation such as hStaufen, PABPI, and eIF4G (1,5,16), and cellular factors involved in posttranscriptional processing of RNA such as CPSF (47) and NS1-BP, a potential splicing-related factor (72). These interactions may be responsible for the alterations in the control of cellular gene expression observed upon expression of NS1 cDNA (18,19,47,57), as well as for the regulation of virus gene expression (8,13).…”

mentioning

confidence: 99%

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Genetic Analysis of Influenza Virus NS1 Gene: a Temperature-Sensitive Mutant Shows Defective Formation of Virus Particles

Garaigorta

Falcón

Ortı́n

2005

J Virol

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To perform a genetic analysis of the influenza A virus NS1 gene, a library of NS1 mutants was generated by PCR-mediated mutagenesis. A collection of mutant ribonucleic proteins containing the nonstructural genes was generated from the library that were rescued for an infectious virus mutant library by a novel RNP competition virus rescue procedure. Several temperature-sensitive (ts) mutant viruses were obtained by screening of the mutant library, and the sequences of their NS1 genes were determined. Most of the mutations identified led to amino acid exchanges and concentrated in the N-terminal region of the protein, but some of them occurred in the C-terminal region. Mutant 11C contained three mutations that led to amino acid exchanges, V18A, R44K, and S195P, all of which were required for the ts phenotype, and was characterized further. Several steps in the infection were slightly altered: (i) M1, M2, NS1, and neuraminidase (NA) accumulations were reduced and (ii) NS1 protein was retained in the nucleus in a temperature-independent manner, but these modifications could not justify the strong virus titer reduction at restrictive temperature. The most dramatic phenotype was the almost complete absence of virus particles in the culture medium, in spite of normal accumulation and nucleocytoplasmic export of virus RNPs. The function affected in the 11C mutant was required late in the infection, as documented by shift-up and shift-down experiments. The defect in virion production was not due to reduced NA expression, as virus yield could not be rescued by exogenous neuraminidase treatment. All together, the analysis of 11C mutant phenotype may indicate a role for NS1 protein in a late event in virus morphogenesis.The influenza A virus genome encodes NS1, a small, nonstructural, and multifunctional protein important for virus-cell interactions (for reviews, see references 22, 33, and 53). It is translated from the colinear transcript of segment 8, which also encodes NS2 protein from a spliced mRNA (31, 34). NS1 accumulates in the nucleus early in the infection (4, 32) and when it is expressed from cDNA (26,35,56), but at late times in the infection it is also found in the cytoplasm (49), in association with polysomes (8,16,32).Although NS1 protein is apparently nonessential, as a recombinant virus has been generated that lacks the gene (23), several virus mutants have been isolated or generated which contain mutations in the NS1 protein and are severely hampered for replication (12,14,17,27,28,40,60,(63)(64)(65). The phenotypes of these mutant viruses indicate that NS1 protein may be involved in several steps in the virus infectious cycle, including transcription and/or replication of virus RNA, late virus protein synthesis, and interference with the cellular gene expression, and that it eventually modulates the virulence of virus infections in vivo (2, 23, 68).NS1 is an RNA-binding protein that has been shown to interact with virion RNA (vRNA) (29, 43), poly(A)-containing RNAs (58), and U6 snRNA (59). The RNA-binding...

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Interaction of influenza virus NS1 protein and the human homologue of Staufen in vivo and in vitro

Cited by 82 publications

References 46 publications

IRF3 and IRF7 Phosphorylation in Virus-infected Cells Does Not Require Double-stranded RNA-dependent Protein Kinase R or IκB Kinase but Is Blocked by Vaccinia Virus E3L Protein

IRF3 and IRF7 Phosphorylation in Virus-infected Cells Does Not Require Double-stranded RNA-dependent Protein Kinase R or IκB Kinase but Is Blocked by Vaccinia Virus E3L Protein

Impact of Protein Kinase PKR in Cell Biology: from Antiviral to Antiproliferative Action

Genetic Analysis of Influenza Virus NS1 Gene: a Temperature-Sensitive Mutant Shows Defective Formation of Virus Particles

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