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The STAT2 activation process is a crucial target of Sendai virus C protein for the blockade of alpha interferon signaling
被引:87
作者:
Gotoh, B
Takeuchi, K
Komatsu, T
Yokoo, J
机构:
[1] Fukui Med Univ, Sch Med, Dept Microbiol, Matsuoka, Fukui 9101193, Japan
[2] Fukui Med Univ, Sch Med, Radioisotope Res Inst, Matsuoka, Fukui 9101193, Japan
关键词:
V-PROTEIN;
MUMPS-VIRUS;
ANTIVIRAL ACTION;
TYROSINE PHOSPHORYLATION;
TRANSCRIPTION FACTOR;
GENE-EXPRESSION;
IN-VITRO;
CELLS;
SIMIAN-VIRUS-5;
PARAMYXOVIRUS;
D O I:
10.1128/JVI.77.6.3360-3370.2003
中图分类号:
Q93 [微生物学];
学科分类号:
071005 ;
100705 ;
摘要:
Sendai virus (SeV) C protein functions as an interferon (IFN) antagonist and renders cells unresponsive to both alpha/beta IFN (IFN-alpha/beta) and IFN-gamma. We have recently found the physical association of the C protein with signal transducer and activator of transcription 1 (STAT1) in infected cells. However, involvement of the C-STAT1 interaction in the blockade of IFN signaling has remained unclear. We generated here a series of C mutant proteins that retained or lost the STAT1-binding capacity and examined their effects on IFN-alpha signaling. All of the C mutant proteins with no STAT1-binding capacity lost the ability to inhibit the IFN-a response. In contrast, the C mutant proteins retaining the STAT1-binding capacity suppressed IFN-alpha-stimulated tyrosine phosphorylation of both STAT2 and STAT1 to various degrees. Remarkably, their anti-IFN-alpha capacities correlated well with the inhibitory effect on phosphorylation of STAT2 rather than STAT1. In infected cells, the levels of tyrosine-phosphorylated (pY) STAT2 were below the detection level irrespective of duration of IFN-alpha stimulation, whereas the levels of pY-STAT1 strikingly increased after long-term IFN-alpha stimulation. These results suggest that the STAT2 activation process is a crucial target for the blockade of IFN-alpha signaling. An in vitro binding assay with extracts from (STAT1-deficient) U3A and (STAT1-expressing) U3A-ST1 cells suggested the requirement of STAT1 for the C-STAT2 interaction. Furthermore, expression of STAT1 enhanced the inhibitory effect of the C protein on STAT2 activation in U3A cells. The C protein thus appears to participate in the inhibitory process for STAT2 activation through the STAT1 interaction.
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页码:3360 / 3370
页数:11
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