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EMBO reports 4, 4, 368–373 (2003)
doi:10.1038/sj.embor.embor802
AOP Published online: 21 March 2003
Phosphorylation of the Stat1 transactivating domain is required for the response to type I interferons
Andreas Pilz1, 3, Katrin Ramsauer1, 3, Hamid Heidari1, Michael Leitges2, Pavel Kovarik1 & Thomas Decker1
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1 Institute of Microbiology and Genetics, Vienna Biocenter, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
2 Max Planck Institute of Experimental Endocrinology, Feodor-Lynen-Strasse 7, D-30625 Hannover, Germany
3 These authors contributed equally to this work
To whom correspondence should be addressed
Thomas Decker Tel: +43 1 4277 54605; Fax: +43 1 4277 9546; decker@gem.univie.ac.at
Received 26 October 2002; Accepted 4 February 2003; Published online 21 March 2003.
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Abstract
Stat1 (signal transducer and activator of transcription 1) regulates transcription in response to the type I interferons IFN- and IFN- , either in its dimerized form or as a subunit of the interferon-stimulated gene factor 3 (Isgf3) complex (consisting of Stat1, Stat2 and interferon-regulating factor 9). Full-length Stat1- and the splice variant Stat1-, which lacks the carboxyl terminus and the Ser727 phosphorylation site, are found in all cell types. IFN-induced phosphorylation of Stat1- on Ser727 occurs in the absence of the candidate kinase, protein kinase C- . When expressed in Stat1-deficient cells, Stat1- and a Stat1-S727A mutant both restored the formation of Stat1 dimers and of the Isgf3 complex on treatment with IFN-. By contrast, only Stat1- restored the ability of IFN- to induce high levels of transcription from target genes of Stat1 dimers and Isgf3 and to induce an antiviral state. Our data suggest an important contribution of the Stat1 C terminus and its phosphorylation at Ser727 to the transcriptional activities of the Stat1 dimer and the Isgf3 complex.
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