A common silencer element in the SCG10 and type II Na⁺ channel genes binds a factor present in nonneuronal cells but not in neuronal cells

We have localized a cell type-specific silencer element in the SCG10 gene by deletion analysis. This neuralrestrictive silencer element (NRSE) selectively represses SCG10 expression in nonneuronal cells and tissues. The NRSE contains a 21 by region with striking homology to a sequence present in a silencer domain of the rat type II sodium channel (Nall), another neuron-specific gene. We have identified a sequence-specific protein(s) that binds the SCG10 NRSE, as well as the homologous element in the Nall gene. A point mutation in the NRSE that abolishes binding of this neural-restrictive silencerbinding factor (NRSBF) in vitro also eliminates silencing activity in vivo. NRSBF is present in nuclear extracts from nonneuronal cells but not in extracts from neuronal cells, suggesting that the neuron-specific expression of SCG10 reflects, at least in part, the absence or inactivity of this protein. These data identify the NRSE as a potentially general DNA element for the control of neuronspecific gene expression in vertebrates.