We report here that immediate early gene pip92 is expressed during anisomycin-induced cell death in fibroblast NIH3T3 cells. To determine the mechanism by which this occurs and to identify downstream signaling pathways, we investigated -the induction of the pip92 promoter. The activation of pip92 by anisomycin is mediated by the activation of MAP kinases, such as JNK and p38 kinase, but not ERK. Deletion analysis of the pip92 promoter indicated that plp92 activation occurs primarily within the region containing a serum response element (SRE). Further analysis of the SRE using a heterologous thymidine kinase promoter showed that both an Ets and CArG-like site are required for anisomycin-induced pip92 expression. Elkl, which binds to the Ets site, was phosphorylated by the JNK- and p38-dependent pathways and the phosphorylation of Elkl-GAL4 fusion proteins by these pathways was sufficient for the transactivation. Overall, this study suggested that different MAPK pathways are involved in the expression of immediate early gene pip92 by growth factors and environmental stresses.
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