Nuclear and cytoplasmic roles of the transcription factor REST

The neuron-restrictive silencer factor (NRSF), also known as repressor element-1 (RE1) silencing transcription factor (REST), is known to act as a transcriptional repressor of neuron-specific genes in nuclei of non-neuronal cells. REST binds a DNA sequence known as neuron-restrictive silencer elements (NRSEs/RE1s) and recruits co-repressors to carry out silencing chromatin modifications. Recent REST ChIP-seq publications have shown that REST binding is not limited to the canonical RE1 sequence, but binds multiple variations of it across the genome.;This study focuses on determining REST's capacity to act as a repressor based on the binding site's degree of correspondence to the canonical RE1 motif. I show that the RE1 right half site acts as a REST-recruiting repressive element. I have also begun studying differential recruitment of REST protein and its cofactors between human embryonic stem cells (hESCs) and hESC-derived neural progenitor cells (NPCs) on a genome-wide scale using chromatin immunoprecipitation followed by massive parallel sequencing of DNA tags (ChIP-seq).;I also present preliminary data suggesting that REST may have a second function as a post-transcriptional activator. Increased luciferase expression is observed when reporter constructs were cotransfected with high levels of REST in mouse Neuro2A (N2A) cells. I show that this concentration dependent function of REST is due to the cell's limited capacity to transport and/or retain REST in the nucleus, where it acts as a repressor. With increasing concentrations of REST, a large fraction remains in the cytoplasm, where REST may bind and stabilize the luciferase transcript and/or enhance its translation.