Regulation of neurite outgrowth and SNAP-25 gene expression by the Brn-3a transcription factor.

SNAP-25 is a presynaptic nerve terminal protein which is also essential for the process of neurite outgrowth in vivo and in vitro. However the processes regulating its expression have not been characterized previously. We show that the gene encoding this protein, SNAP, is strongly activated by the Brn-3a POU (Pit-Oct-Unc) family transcription factor. Expression of both Brn-3a and SNAP-25 increases when ND7 neuronal cells are induced to extend neurite processes by serum removal. Inhibition of Brn-3a expression in these cells inhibits SNAP-25 expression and abolishes the neurite outgrowth that normally occurs in response to serum removal. These results identify Brn-3a as the first transcription factor having a role in process outgrowth in neuronal cells acting, at least in part, via the activation of SNAP-25 gene expression.