Title: Pluripotency factors and Polycomb Group proteins repress aryl hydrocarbon receptor expression in murine embryonic stem cells.
Authors: Ko, Chia-I; Wang, Qin; Fan, Yunxia; Xia, Ying; Puga, Alvaro
Published In Stem Cell Res, (2014 Jan)
Abstract: The aryl hydrocarbon receptor (AHR) is a transcription factor and environmental sensor that regulates expression of genes involved in drug-metabolism and cell cycle regulation. Chromatin immunoprecipitation analyses, Ahr ablation in mice and studies with orthologous genes in invertebrates suggest that AHR may also play a significant role in embryonic development. To address this hypothesis, we studied the regulation of Ahr expression in mouse embryonic stem cells and their differentiated progeny. In ES cells, interactions between OCT3/4, NANOG, SOX2 and Polycomb Group proteins at the Ahr promoter repress AHR expression, which can also be repressed by ectopic expression of reprogramming factors in hepatoma cells. In ES cells, unproductive RNA polymerase II binds at the Ahr transcription start site and drives the synthesis of short abortive transcripts. Activation of Ahr expression during differentiation follows from reversal of repressive marks in Ahr promoter chromatin, release of pluripotency factors and PcG proteins, binding of Sp factors, establishment of histone marks of open chromatin, and engagement of active RNAPII to drive full-length RNA transcript elongation. Our results suggest that reversible Ahr repression in ES cells holds the gene poised for expression and allows for a quick switch to activation during embryonic development.
PubMed ID: 24316986
MeSH Terms: Animals; Cell Differentiation; Cells, Cultured; Chromatin/metabolism; Embryonic Stem Cells/cytology*; Embryonic Stem Cells/metabolism; Gene Expression Regulation*; Histones/metabolism; Mice; Mice, Inbred C57BL; Phosphorylation; Polycomb-Group Proteins/genetics; Polycomb-Group Proteins/metabolism*; Promoter Regions, Genetic; Protein Binding; RNA Polymerase II/metabolism; Receptors, Aryl Hydrocarbon/genetics; Receptors, Aryl Hydrocarbon/metabolism*; Sp3 Transcription Factor; Transcription Factors/genetics; Transcription Factors/metabolism*; Transcription Initiation Site