Transcriptional regulatory elements downstream of the JunB gene.

JunB is an immediate early transcription factor that is induced by a variety of extracellular signaling agents, including growth factors, phorbol esters, and agents that elevate cyclic AMP. The mechanism of activation of the gene encoding JunB by these agents is not well understood. By using the JunB gene together with flanking DNA in transfection experiments, we show that a serum response element (SRE) and/or a cAMP response element (CRE) downstream of the gene mediate the response of the gene in mouse NIH 3T3 cells to serum, platelet-derived growth factor, basic fibroblast growth factor, phorbol ester, and forskolin. In addition, a segment of DNA just upstream of the TATA box is required for optimal activation of the gene. IMAGES: