AP-1 activity rises by stimulation-dependent c-Fos expression in auditory neurons

Acoustical or intracochlear stimulation may induce expression of the immediate early gene product c-Fos in neurons throughout the auditory brainstem. Attempting to estimate its consequences, we sought to determine if c-Fos expression occurs in neurons that also contain c-Jun p39 with which it could form the heterodimeric transcription factor AP-1 to activate a large number of genes, among them several involved in neuroplastic remodeling. Following intracochlear stimulation, c-Fos and c-Jun were found to be colocalized in nuclei of many neurons at all levels of the subcortical auditory system. We conclude that stimulation triggers Fos–Jun dimerization, causing cascades of gene expression that potentially culminate in structural changes of neurons affected by the specific pattern of activity imposed on the neuronal system.