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J Biol Chem. 2003 May 2;278(18):15495-504. Epub 2003 Feb 25.

Interferon regulatory factor-7 synergizes with other transcription factors through multiple interactions with p300/CBP coactivators.

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1
Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267-0576, USA.

Abstract

Interferon regulatory factor (IRF)-7 is activated in response to virus infection and stimulates the transcription of a set of cellular genes involved in host antiviral defense. The mechanism by which IRF-7 is activated and cooperates with other transcription factors is not fully elucidated. Activation of IRF-7 results from a conformational change triggered by the virus-dependent phosphorylation of its C terminus. This conformational change leads to dimerization, nuclear accumulation, DNA-binding, and transcriptional transactivation. Here we show that activation of IRF-7, like that of IRF-3, is dependent on modifications of two distinct sets of Ser/Thr residues. Moreover, we show that different virus-inducible cis-acting elements display requirements for specific IRFs. In particular, the virus-responsive element of the ISG15 gene promoter can be activated by either IRF-3 or IRF-7 alone, whereas the P31 element of the interferon-beta gene is robustly activated only when IRF-3, IRF-7, and the p300/CBP coactivators are all present. Furthermore, we find that IRF-7 interacts with four distinct regions of p300/CBP. These interactions not only stimulate the intrinsic transcriptional activity of IRF-7, but they are also indispensable for its ability to strongly synergize with other transcription factors, including c-Jun and IRF-3.

PMID:
12604599
DOI:
10.1074/jbc.M212940200
[Indexed for MEDLINE]
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