Dominant-negative activity of the STAT3-Y705F mutant depends on the N-terminal domain

Cell Communication and Signaling

Research

Gerhard Müller-Newen¹  Anne Mohr¹  Dirk Fahrenkamp¹  Natalie Rinis¹ 

[1] Institut für Biochemie und Molekularbiologie, RWTH Aachen University, Pauwelsstraße 30, 52074, Aachen, Germany;

关键词: JAK-STAT signaling;    STAT3;    IL-6;    STAT3-YF mutant;    Dominant-negative;    Hyper-IgE syndrome (HIES);   

DOI  :  10.1186/1478-811X-11-83

 received in 2013-05-15, accepted in 2013-10-25,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundSTAT3 is a transcription factor of central importance in chronic inflammation and cancer. In response to cytokine stimulation STAT3 is phosphorylated on a single tyrosine residue at position 705, dimerizes and accumulates in the nucleus to induce target gene expression. The substitution of tyrosine 705 to phenylalanine leads to a dominant-negative STAT3 mutant (STAT3-YF) which influences the activation of WT-STAT3 in stimulated cells through a mechanism that is not completely understood. In this study we analyzed the molecular mechanism of STAT3-YF dominant-negative activity in IL-6-induced STAT3 signaling and the relevance of the N-terminal domain.ResultsExpression of STAT3-YF-YFP impairs tyrosine phosphorylation, nuclear translocation and the transcriptional activity of WT-STAT3 in IL-6-stimulated cells. The fluorescently labelled STAT3-YF mutant binds to a phosphorylated gp130 receptor-peptide comparable to WT-STAT3-YFP. STAT3-YF-YFP forms homodimers as well as heterodimers with WT-STAT3 in the presence and absence of IL-6. The preformed heterodimers in unstimulated cells are detectable by colocalization of STAT3-CFP with STAT3-YF-YFP fused to a nuclear localization signal. STAT3/STAT3-YF heterodimers are not able to bind to DNA in stimulated cells, but the presence of the mutant reduces DNA-binding of WT-STAT3 homodimers. STAT3-YF-ΔN-YFP lacking the N-terminal domain forms no dimers and only marginally affects the activity of WT-STAT3.ConclusionOur findings demonstrate that dominant-negative STAT3-YF affects the activation of WT-STAT3 at multiple levels. Unexpectedly, the N-terminal domain of STAT3-YF plays an important role for the dominant-negative effect. We show that (i) STAT3-YF competes with WT-STAT3 in binding to activated gp130-receptors, (ii) the formation of WT-STAT3/STAT3-YF heterodimers in IL-6-stimulated cells results in inactive, semiphosphorylated dimers which do not bind to DNA and thus fail to induce target gene expression, (iii) the N-terminal domain-mediated formation of preformed STAT3/STAT3-YF heterodimers in unstimulated cells which affects the IL-6-induced homodimerization of WT-STAT3 contributes to the dominant-negative effect of STAT3-YF. These findings will contribute to our understanding of naturally occuring dominant-negative STAT3 mutants that cause the hyper-IgE syndrome.

【 授权许可】

Unknown   
© Mohr et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.