TRANSCRIPTION FACTOR P91 INTERACTS WITH THE EPIDERMAL GROWTH-FACTOR RECEPTOR AND MEDIATES ACTIVATION OF THE C-FOS GENE PROMOTER

Transcription factor p91 contains a SH2 domain and is activated by tyrosine phosphorylation. Here we demonstrate that epidermal growth factor (EGF) induces rapid tyrosine phosphorylation and nuclear translocation of p91. Through its SH2 domain, p91 directly interacts with the EGF receptor in a ligand-dependent manner. p91 is a necessary component of an EGF-induced DNA-binding factor that recognizes a previously identified regulatory element, SIE (c-sis-inducible element), in the c-fos gene promoter. Activated pg1 stimulates SIE-dependent transcription in vitro. Cotransfection of an SIE-containing reporter with a p91 expression vector shows that p91 is a positive transcriptional regulator of the c-fos gene promoter. These studies suggest that EGF uses a direct signaling pathway to control nuclear transcriptional events.