A single zinc finger motif in the silencing factor REST represses the neural-specific type II sodium channel promoter

The type II voltage-dependent sodium channel is present in neuronal cells, where it mediates the propagation of nerve impulses. Restricted expression of the type II sodium channel gene to neurons is due, at least in part, to binding of the repressor protein REST (also termed NRSF or XBR) to the RE1 (also called NRSE) sequence in the type II sodium channel gene. Previous studies have shown that a domain in REST containing eight GL1-Krüppel zinc finger motifs mediates DNA binding. Deletional and GAL4-fusion gene analyses now reveal repressor domains that lie outside of the DNA-binding domain in both the amino and carboxyl termini of REST. Mutational analysis further identifies a single zinc finger motif in the carboxyl-terminal domain as being essential for repressing type II sodium channel reporter genes. These studies reveal two domains in REST that may mediate interactions with other proteins involved in restricting expression of a large set of genes to the vertebrate nervous system.

REST: a mammalian silencer protein that restricts sodium channel gene expression to neurons

Expression of the type II voltage-dependent sodium channel gene is restricted to neurons by a silencer element active in nonneuronal cells. We have cloned cDNA coding for a transcription factor (REST) that binds to this silencer element. Expression of a recombinant REST protein confers the ability to silence type II reporter genes in neuronal cell types lacking the native REST protein, whereas expression of a dominant negative form of REST in nonneuronal cells relieves silencing mediated by the native protein. REST transcripts in developing mouse embryos are detected ubiquitously outside of the nervous system. We propose that expression of the type II sodium channel gene in neurons reflects a default pathway that is blocked in nonneuronal cells by the presence of REST.