The Repressor Element Silencing Transcription Factor (REST)-mediated Transcriptional Repression Requires the Inhibition of Sp1

Valérie Plaisance,Vincent Lenain,Jacques-Antoine Haefliger,Gérard Waeber,Guy Niederhauser,Amar Abderrahmani,Fayçal Azzouz

doi:10.1074/jbc.m411825200

Abstract

The terminal differentiation of neuronal and pancreatic beta-cells requires the specific expression of genes that are targets of an important transcriptional repressor named RE-1 silencing transcription factor (REST). The molecular mechanism by which these REST target genes are expressed only in neuronal and beta-cells and are repressed by REST in other tissues is a central issue in differentiation program of neuronal and beta-cells. Herein, we showed that the transcriptional factor Sp1 was required for expression of most REST target genes both in insulin-secreting cells and neuronal-like cells where REST is absent. Inhibition of REST in a non-beta and a non-neuronal cell model restored the transcriptional activity of Sp1. This activity was also restored by trichostatin A indicating the requirement of histone deacetylases for the REST-mediated silencing of Sp1. Conversely, exogenous introduction of REST blocked Sp1-mediated transcriptional activity. The REST inhibitory effect was mediated through its C-terminal repressor domain, which could interact with Sp1. Taken together, these data show that the inhibition of Sp1 by REST is required for the silencing of its target genes expression in non-neuronal and in non-beta-cells. We conclude that the interplay between REST and Sp1 determines the cell-specific expression of REST target genes.

Highlights

Pancreatic ␤-cells and neuronal cells share a large number of similarities, including a restricted expression pattern of genes that contain a cis repressor element of 23 bp termed RE-1 or neuron-restrictive silencer element (NRSE)1 (1–5)
Connexin36 Complexin 1 (Cplx1) Superior cervical ganglion-10 protein (SCG10) Synapsin I (SYNI) N-Methyl-D-aspartate receptor subunit 1 (NMDA) Glutamate receptor 2 (GluR2) Glycine receptor subunit ␣ 1 PAX4 G protein-coupled receptor (GPR10) Brain-derived neurotrophic factor (BDNF) Dynamin I Corticotropin-releasing hormone gene transcription (CRH) Type II sodium channel Cell adhesion molecule L1 m4 muscarinic acetylcholine receptor constructs followed by co-immunoprecipitation and transfection assays indicated that the C-terminal repressor domain (CTRD) of RE-1 silencing transcription factor (REST) was required for interaction with Sp1 and inhibited its activity
To assess the functionality of G/C box sequences on expression of other REST target genes, ␤TC3 cells and PC12 cells that contain a detectable expression of some REST target genes (6) were treated with mithramycin A, a DNA-binding drug that binds to G/C-specific regions of DNA including G/C box sequences

Summary

Introduction

Pancreatic ␤-cells and neuronal cells share a large number of similarities, including a restricted expression pattern of genes that contain a cis repressor element of 23 bp termed RE-1 or neuron-restrictive silencer element (NRSE) (1–5). Target genes of REST include those encoding Nav1.2 sodium channel (4), SCG10 (9), synapsin I (2, 3, 10), the GluR2 glutamate receptor subunit (11), subunits of the muscarinic acetylcholine receptor (12), islet-brain-1/c-Jun Nterminal kinase-interacting protein-1 (IB1) (6, 13), complexin I, and connexin 36 (14) These genes have been shown to be mandatory for neuronal and ␤-cell functions. Connexin Complexin 1 (Cplx1) Superior cervical ganglion-10 protein (SCG10) Synapsin I (SYNI) N-Methyl-D-aspartate receptor subunit 1 (NMDA) Glutamate receptor 2 (GluR2) Glycine receptor subunit ␣ 1 PAX4 G protein-coupled receptor (GPR10) Brain-derived neurotrophic factor (BDNF) Dynamin I Corticotropin-releasing hormone gene transcription (CRH) Type II sodium channel Cell adhesion molecule L1 m4 muscarinic acetylcholine receptor constructs followed by co-immunoprecipitation and transfection assays indicated that the CTRD of REST was required for interaction with Sp1 and inhibited its activity. We propose that the silencing of Sp1 by REST is a required event to determine the ␤-cell and the neuronal cell expression of REST target genes

Methods

Results

Conclusion