In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 103, No. 10 ( 2006-03-07), p. 3840-3845
Abstract:
Type I IFNs are crucial components of the innate immune response to viral attack. They are rapidly synthesized and secreted after infection with human cytomegalovirus (CMV) and trigger a signal transduction pathway that involves successive activation and nuclear translocation of signal transducer and activator of transcription 1 (STAT1) and STAT2. The activated STATs, together with the IFN regulatory factor 9 protein, form a trimeric transcription complex (IFN-stimulated gene factor 3) that stimulates expression of numerous IFN-responsive genes, many of which exhibit antiviral activity. Here we demonstrate that the viral 72-kDa IE1 protein (IE1-72kDa) confers partial resistance to the antiviral activity of type I IFNs upon CMV. Accordingly, IFN-responsive transcripts accumulate to substantially increased levels after infection with an IE1-deficient mutant as compared with wild-type virus, and ectopic expression of the viral protein in stably transfected cells is sufficient to block their induction. We further show that IE1-72kDa forms a physical complex with STAT1 and STAT2 in nuclei of infected cells and in vitro and prevents association of STAT1, STAT2, and IFN regulatory factor 9 with promoters of IFN-responsive genes in vivo . Our results indicate that the viral protein blocks an intranuclear step after nuclear translocation and before DNA binding of IFN-stimulated gene factor 3, presumably by interfering with the integrity and/or correct subnuclear localization of the protein complex. This study identifies the CMV IE1-72kDa protein as a viral antagonist of the cellular innate immune response, inhibiting IFN-dependent STAT signaling by means of an unprecedented molecular mechanism.
Type of Medium:
Online Resource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.0600007103
Language:
English
Publisher:
Proceedings of the National Academy of Sciences
Publication Date:
2006
detail.hit.zdb_id:
209104-5
detail.hit.zdb_id:
1461794-8
SSG:
11
SSG:
12
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