Early Growth Response 1 (EGR) is an immediate early gene that is rapidly expressed downstream of a number of stimuli. It encodes a Cys2-His2 zinc finger transcription factor that regulates expression of genes involved in stress response, differentiation and neuronal development (reviewed in Pagel and Deindl, 2001; Bahrami and Drabløs, 2016; Perez-Cadahia et al, 2011; Herdegen and Leah, 1998; O'Donovan et al, 1999).
Expression of EGR1 depends on binding of phosphorylated TCF protein ELK1 and its transcriptional coactivator SRF (serum response factor) to their cognate DNA binding sequences in the promoters (Hooker et al, 2017; De Franco et al, 1993; Harada et al, 2001; reviewed in Herdegen and Leah, 1998). In addition to SRF and TCF binding sites, the EGR1 promoter also contain consensus binding sequences for AP-1 and CREB, as well as binding sites for EGR1 protein itself (Schwachtgen et al, 2000; Thiel et al, 2000; Svaren et al, 1996; David et al, 2005; Tyan et al, 2008; reviewed in Page; and Deindl, 2001). Expression of EGR1 is limited by a negative feedback loop mediated by the binding of a complex of EGR1 protein with a repressor protein of the NAB family (NGF1A binding protein) to the EGR1 binding site (Cao et al, 1990; Thiel et al, 2000; Svaren et al, 1996).