AKT1-Dependent Activation of NF-κB by the L Protein of Parainfluenza Virus 5

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The viral RNA-dependent RNA polymerases (vRdRps) of nonsegmented, negative-sense viruses (NNSVs) consist of the enzymatic large protein (L) and the phosphoprotein (P). P is heavily phosphorylated, and its phosphorylation plays a critical role in viral RNA synthesis. Since NNSVs do not encode kinases, P is phosphorylated by host kinases. In this study, we investigate the roles that viral proteins play in the phosphorylation of mumps virus (MuV) P. We found that nucleoprotein (NP) enhances the phosphorylation of P. We have identified the serine/threonine kinase Polo-like kinase 1 (PLK1) as a host kinase that phosphorylates P and have found that phosphorylation of P by PLK1 is enhanced by NP. The PLK1 binding site in MuV P was mapped to residues 146 to 148 within the S(pS/T)P motif, and the phosphorylation site was identified as residues S292 and S294. IMPORTANCEIt has previously been shown that P acts as a chaperone for NP, which encapsidates viral genomic RNA to form the NP-RNA complex, the functional template for viral RNA synthesis. Thus, it is assumed that phosphorylation of P may regulate NP's ability to form the NP-RNA complex, thereby regulating viral RNA synthesis. Our work demonstrates that MuV NP affects phosphorylation of P, suggesting that NP can regulate viral RNA synthesis by regulating phosphorylation of P. Many human and animal pathogens, such as mumps virus (MuV), Sendai virus (SeV), human respiratory syncytial virus (RSV), the parainfluenza viruses, measles virus (MeV), J paramyxovirus (JPV), Hendra virus (HeV), and Nipah virus (NiV), are in the Paramyxoviridae family of the Mononegavirales (1). The nonsegmented, negative-stranded RNA genome of these viruses is encapsidated by the nucleoprotein (NP) to produce the helical nucleocapsid that functions as the template for viral RNA synthesis. The viral RNA-dependent RNA polymerase (vRdRp), which minimally consists of the phosphoprotein (P) and the large protein (L), functions for both transcription and replication of the viral RNA genome. The enzymatic activities of the L protein are responsible for initiation, elongation, and termination of RNA synthesis, and the L protein functions to add the 5= cap and 3= poly(A) sequences to transcribed viral mRNA (1). P protein interacts with NP to dock the vRdRp to the NP-RNA template.The P proteins of paramyxoviruses are highly phosphorylated, and phosphorylation of these proteins has been shown to play critical roles in regulating viral mRNA synthesis (2-7). Phosphorylation of residues within the P protein of parainfluenza virus 5 (PIV5), a prototypical paramyxovirus, plays both negative and positive roles in mRNA synthesis (3-5). A phosphorylation site at S157 was found in the P protein of PIV5-infected cells (3). Further studies indicate that Polo-like kinase 1 (PLK1) associates with S157 and phosphorylates the PIV5 P protein at S308 (3, 4). Phosphorylation of both of these residues reduces viral gene expression and prevents cytokine induction and cell death. This report shows that P phosphorylatio...

Section: Discussionsupporting

confidence: 42%

Mumps Virus Nucleoprotein Enhances Phosphorylation of the Phosphoprotein by Polo-Like Kinase 1

Pickar

Zengel

et al. 2016

Self Cite

“…This finding is in agreement with previous observations that VSV replication induces the dephosphorylation of 4EB-P1 (21) and downstream effectors of Akt (42) and that VSV replication is not dependent on an active PI3k/Akt signaling pathway (24). This runs counter to what has been seen for other viruses and even other negative-strand RNA viruses, such as influenza A virus and RSV, which are known to activate Akt (26,41,60). VSV's inactivation of Akt is reminiscent of the Akt inhibition seen during measles infection (6).…”

Section: Discussioncontrasting

confidence: 56%

Dominant Inhibition of Akt/Protein Kinase B Signaling by the Matrix Protein of a Negative-Strand RNA Virus

Dunn

Connor

2011

Vesicular stomatitis virus (VSV) is a rhabdovirus that alters host nuclear and cytoplasmic function upon infection. We have investigated the effect of VSV infection on cellular signaling through the phosphatidylinositol-3 kinase (PI3k)/Akt signaling pathway. Akt phosphorylation at both threonine 308 (Thr308) and serine 473 (Ser473) was inhibited in cells infected with VSV. This inhibition was rapid (beginning within the first 2 to 3 h postinfection) and correlated with the dephosphorylation of downstream effectors of Akt, such as glycogen synthase kinase 3␤ (GSK3␤) and mammalian target of rapamycin (mTOR). The dephosphorylation of Akt occurred in the presence of growth factor stimulation and was not overcome through constitutive membrane targeting of Akt or high levels of phosphatidylinositol-3,4,5-triphosphate (PIP3) accumulation in the membrane. Akt dephosphorylation was not a result of alterations in PDK1 phosphorylation or activity, changes in phosphatase and tensin homologue deleted on chromosome 10 (PTEN) levels, or the downregulation of PI3k signaling. Inactivation of Akt was caused by the expression of the viral M protein in the absence of other viral components, and an M protein mutant that does not inhibit RNA polymerase II (Pol II) transcription and nuclear/cytoplasmic transport was also defective in inhibiting Akt phosphorylation. These data illustrate that VSV utilizes a novel mechanism to alter this central player in cell signaling and oncogenesis. It also suggests an inside-out model of signal transduction where VSV interruption of nuclear events has a rapid and significant effect on membrane signaling events.

“…The L protein has six domains that are highly conserved among all members of the order Mononegavirales (22,23). It has been reported that domains I and II of the parainfluenza virus 5 L protein activate NF-B through an AKT-dependent pathway and that the mRNA of domain II of L can induce IFN-␤ expression through an RNase L-MDA5-dependent pathway (24,25). Interestingly, two differences between the L genes of L-LW and L-BH are in domain II.…”

Section: Discussionmentioning

confidence: 99%

The L Gene of J Paramyxovirus Plays a Critical Role in Viral Pathogenesis

Chen

et al. 2013

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f J paramyxovirus (JPV) was first isolated from moribund mice with hemorrhagic lung lesions in Australia in the 1970s. Recent sequencing of JPV (JPV-LW) confirms that JPV is a paramyxovirus with several unique features. However, neither JPV-LW nor a recombinant JPV based on its sequence (rJPV-LW) caused obvious illness in mice. In this work, we analyzed a different JPV isolate (JPV-BH), which behaved differently from JPV-LW; JPV-BH grew more slowly in Vero cells and had less of a cytopathic effect on tissue culture cells but caused severe disease in mice. We have determined the whole genome sequence of JPV-BH. There were several nucleotide sequence differences between JPV-BH and JPV-LW, one in the leader sequence, one in the GX gene, and three in the L gene. The high sequence identity between JPV-BH and JPV-LW suggests that JPV-BH and JPV-LW are the same virus strain but were obtained at different passages from different laboratories. To understand the roles of these nucleotide sequence differences in pathogenicity in mice, we generated a recombinant JPV-BH strain (rJPV-BH) and hybrid rJPV-BH strains with sequences from the leader sequence (rJPV-BH-Le-LW), the GX gene (rJPV-BH-GX-LW), and the L gene (rJPV-BH-L-LW) of JPV-LW and compared their pathogenicities in mice. We have found that rJPV-BH-L-LW was attenuated in mice, indicating that nucleotide sequence differences in the L gene play a critical role in pathogenesis.