A Stat1alpha factor regulates the expression of the human vimentin gene by IFN-gamma.

Vimentin is an intermediate filament protein normally expressed in cells of mesenchymal origin. Here, we report an increase in vimentin gene transcription induced by the cytokine interferon-y (IFN-gamma). Northern blot analysis and reporter gene assays reveal that IFN-gamma induces vimentin gene transcription in HeLa cells. However, no increase in vimentin mRNA synthesis was observed de novo in MCF-7 cells, which do not already express vimentin. Band shift analysis shows that the Stat1alpha protein mediates vimentin induction by IFN-gamma. A human mutant fibroblast cell line (U3A), which lacks Stat1alpha but expresses vimentin mRNA, yields no increase in vimentin mRNA levels on the addition of IFN-gamma. These results suggest that the induction of vimentin gene expression might be an important part of a complex cellular response to IFN-gamma.