The mumps virus V protein is unstable in virus infected cells

ABSTRACT It has been reported that mumps virus protein V or the C-terminal Cys-rich region of protein V (Vsp) is associated with blocking of the interferon (IFN) signal transduction pathway through a decrease in STAT-1 production. The intracellular target of the V protein was investigated by using a two-hybrid screening system with Vsp as bait. Full-length V protein and Vsp were able to bind to RACK1, and the interaction did not require two WD domains, WD1 and WD2, in RACK1. A significant interaction between V protein and RACK1 was also demonstrated in cells persistently infected with mumps virus (FLMT cells), and the formation of the complex was not affected by treatment with IFN. On the other hand, in uninfected cells, STAT-1 was associated with the long form of the β subunit of the alpha IFN receptor, and this association was mediated by the function of RACK1 as an adaptor protein. Immunoprecipitation and glutathione S-transferase pull-down experiments revealed that the association of RACK1 or mumps virus V protein with the IFN receptor was undetectable in mumps virus-infected cells. Furthermore, RACK1 interacted with mumps virus V protein with a higher affinity than STAT-1 did. Therefore, it is suggested that mumps virus V protein has the ability to interact strongly with RACK1 and consequently to bring about the disruption of the complex formed from STAT-1, RACK1, and the IFN receptor.

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Mumps Virus V Protein Antagonizes Interferon without the Complete Degradation of STAT1

Journal of Virology ◽

10.1128/jvi.79.7.4451-4459.2005 ◽

2005 ◽

Vol 79 (7) ◽

pp. 4451-4459 ◽

Cited By ~ 30

Author(s):

Toru Kubota ◽

Noriko Yokosawa ◽

Shin-ichi Yokota ◽

Nobuhiro Fujii ◽

Masato Tashiro ◽

...

Keyword(s):

Protein Function ◽

Nuclear Translocation ◽

Cysteine Residue ◽

Mumps Virus ◽

Unique Region ◽

V Protein ◽

Complete Degradation ◽

Infected Cells ◽

Induced Signal ◽

Viral Components

ABSTRACT Mumps virus (MuV) has been shown to antagonize the antiviral effects of interferon (IFN) through proteasome-mediated complete degradation of STAT1 by using the viral V protein (T. Kubota et al., Biochem. Biophys. Res. Commun. 283:255-259, 2001). However, we found that MuV could inhibit IFN signaling and the generation of a subsequent antiviral state long before the complete degradation of cellular STAT1 in infected cells. In MuV-infected cells, nuclear translocation and phosphorylation of STAT1 and STAT2 tyrosine residue (Y) at 701 and 689, respectively, by IFN-β were significantly inhibited but the phosphorylation of Jak1 and Tyk2 was not inhibited. The transiently expressed MuV V protein also inhibited IFN-β-induced Y701-STAT1 and Y689-STAT2 phosphorylation, suggesting that the V protein could block IFN-β-induced signal transduction without the aid of other viral components. Finally, a substitution of an alanine residue in place of a cysteine residue in the C-terminal V-unique region known to be required for STAT1 degradation and inhibition of anti-IFN signaling resulted in the loss of V protein function to inhibit the Y701-STAT1 and Y689-STAT2 phosphorylation.

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Detection and characterization of mumps virus V protein

Virology ◽

10.1016/0042-6822(90)90400-l ◽

1990 ◽

Vol 178 (1) ◽

pp. 247-253 ◽

Cited By ~ 30

Author(s):

Kaoru Takeuchi ◽

Kiyoshi Tanabayashi ◽

Michiko Hishiyama ◽

Yasuko K. Yamada ◽

Akio Yamada ◽

...

Keyword(s):

Mumps Virus ◽

V Protein

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C-Terminal Region of STAT-1α Is Not Necessary for Its Ubiquitination and Degradation Caused by Mumps Virus V Protein

Journal of Virology ◽

10.1128/jvi.76.24.12683-12690.2002 ◽

2002 ◽

Vol 76 (24) ◽

pp. 12683-12690 ◽

Cited By ~ 61

Author(s):

Noriko Yokosawa ◽

Shin-ichi Yokota ◽

Toru Kubota ◽

Nobuhiro Fujii

Keyword(s):

Amino Acid ◽

Transcriptional Activation ◽

Tandem Repeats ◽

Mumps Virus ◽

Terminal Region ◽

Single Amino Acid ◽

Luciferase Reporter ◽

Enhancer Element ◽

V Protein ◽

Gene Assay

ABSTRACT Constitutive levels of production of STAT-1 were reduced by 10 h postinfection (p.i.) and significantly lost by 24 h p.i. in FL cells acutely infected with mumps virus (MuV). This result was consistent with that observed in previous studies and experiments with cells persistently infected with MuV (FLMT cells). There was a marked decrease in the amount of STAT-1 in cells expressing MuV accessory protein V (MuV-V). Furthermore, single amino acid substitutions in the Cys-rich region of V protein (Vc189a, Vc207a, and Vc214a) showed that each cysteine residue plays an important role in the decrease in STAT-1 production, but substitution of a histidine residue at amino acid position 203 had no effect. These events and the resultant suppression of the alpha interferon (IFN-α) response were confirmed by a luciferase reporter gene assay with five tandem repeats of the IFN-α-stimulated response element as an enhancer element of the firely luciferase gene. STAT-1 production was restored and detectable in FLMT cells treated with a proteosome inhibitor, such as MG132 or lactacystin. In the presence of MG132, ubiquitination of STAT-1 and the interaction of MuV-V with STAT-1 were demonstrated in FLMT cells by immunoprecipitation with anti-STAT-1 antibody. The same results for the interaction and ubiquitination were obtained in experiments with an expression vector for a C-terminal deletion mutant of STAT-1. The truncated STAT-1 molecules were degraded in the presence of MuV-V. Therefore, the C-terminal region (transcriptional activation and Src homology 2 domains) of STAT-1 is not necessary for its degradation caused by MuV-V. Our data suggest that MuV-V promotes ubiquitination and degradation of STAT-1.

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The Paramyxovirus Simian Virus 5 V Protein Slows Progression of the Cell Cycle

Journal of Virology ◽

10.1128/jvi.74.19.9152-9166.2000 ◽

2000 ◽

Vol 74 (19) ◽

pp. 9152-9166 ◽

Cited By ~ 89

Author(s):

Grace Y. Lin ◽

Robert A. Lamb

Keyword(s):

Cell Cycle ◽

Cell Cycle Progression ◽

Simian Virus ◽

S Phase ◽

V Protein ◽

Simian Virus 5 ◽

C Terminus ◽

M Phase ◽

Infected Cells ◽

Affect Cell Cycle Progression

ABSTRACT Infection of cells by many viruses affects the cell division cycle of the host cell to favor viral replication. We examined the ability of the paramyxovirus simian parainfluenza virus 5 (SV5) to affect cell cycle progression, and we found that SV5 slows the rate of proliferation of HeLa T4 cells. The SV5-infected cells had a delayed transition from G1 to S phase and prolonged progression through S phase, and some of the infected cells were arrested in G2 or M phase. The levels of p53 and p21CIP1were not increased in SV5-infected cells compared to mock-infected cells, suggesting that the changes in the cell cycle occur through a p53-independent mechanism. However, the phosphorylation of the retinoblastoma protein (pRB) was delayed and prolonged in SV5-infected cells. The changes in the cell cycle were also observed in cells expressing the SV5 V protein but not in the cells expressing the SV5 P protein or the V protein lacking its unique C terminus (VΔC). The unique C terminus of the V protein of SV5 was shown previously to interact with DDB1, which is the 127-kDa subunit of the multifunctional damage-specific DNA-binding protein (DDB) heterodimer. The coexpression of DDB1 with V can partially restore the changes in the cell cycle caused by expression of the V protein.

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