Growth factor-mediated induction of the delayed early gene T1 depends on a 12-O-tetradecanoylphorbol 13-acetate-responsive element located 3.6 kb upstream of the transcription initiation site.

Abstract

The T1 gene is a delayed early serum-responsive gene which encodes a secreted glycoprotein of the immunoglobulin superfamily. We have addressed the question of what promoter elements are needed to allow for growth factor-mediated T1 gene expression. By deletion analysis we have identified a 448-bp DNA region 3.5-4.0 kb upstream of the transcription start site which can confer serum inducibility onto a foreign minimal promoter. Within this sequence there is a 12-O-tetradecanoylphorbol 13-acetate (TPA)-responsive element (TRE) which is essential for T1 promoter induction in response to the forced expression of the transcription factor AP-1 in NIH 3T3 fibroblasts and F9 teratocarcinoma cells. This TRE is crucial for growth factor-mediated T1 gene expression. A point mutation within this TRE attenuated serum inducibility. Two E boxes are positioned 6 and 40 bp downstream of the TRE. Point mutations within these sequence motifs reduced basal T1 promoter activity and serum inducibility. Additional, as-yet-unidentified, promoter elements within the 448-bp serum-responsive region are required for T1 gene activation in response to growth stimulation.