Regulation of early growth response-1 gene expression and signaling mechanisms in neuronal cells: Physiological stimulation and stress

Extracellular signals trigger important adaptative responses that enable an organism to cope with a changing environment. The induction of immediate early genes is a key initial event in responses to diverse stimuli as changes in inducible transcription factor expression lead to a complex array in transcriptional control signals for use in the coordination of late response gene expression. The early growth response-1 (Egr-1), first identified as an immediate early gene induced by mitogenic stimulation, and subsequently shown to be activated by diverse exogenous stimuli including growth factors, hormones and neurotransmitters, encodes for a zinc finger transcription factor involved in the regulation of growth and differentiation. This article reviews recent findings about the expression, the signaling pathways, and the biological activity of Egr-1 in neuronal cells, following differentiation and apoptosis, as paradigms for nervous system functioning under physiological and stress-related conditions.