Expression and Regional Induction of c-fos Gene in the Central Nervous System After Brain Injury

Abstract

The proto-oncogene c-fos encodes a nuclear phosphoprotein which is thought to act as transcriptional regulatory protein for a specific set of genes (1-4). The c-fos is able to form a complex with other proteins, one of which was recently identified as the c-jun protein. This complex (c-fos and c-jun heterodimer) has DNA binding properties, and its DNA target sequence was recently shown to be the activator protein-1 (AP-1) binding site (5,6). The strong induction of c-fos expression after growth factor stimulation suggests that the c-fos protein may be involved in the regulation of specific sets of genes controlling growth and differentiation (7,8). Moreover, the presence and induction of the c-fos gene in the adult nervous system suggest that its protein product may play a role in neuronal plasticity. In the brain, c-fos protein is present in basal amounts and is elevated by many sorts of stimuli. For example, it is rapidly and transiently induced in hippocampus and other regions by seizure activity (9-11). A specific pattern of c-fos immunoreactivity was observed after cortical stimulation in adult brain (12) and after sensory stimulation in spinal cord (13). However, there is also some evidence that c-fos induction could be a consequence of stress or physical damage to the brain (14).