Enhancers make non-coding RNA

Abstract

Genomes don't just encode protein-coding RNAs. They also give rise to various groups of RNAs that can regulate gene expression. Short RNAs that form from enhancer sequences might be one such class of regulatory RNA. Regulatory proteins bind non-coding DNA either close to a gene's mRNA transcription start site at a promoter, or further away on the genome at an enhancer. Enhancers act by helping to recruit the RNA polymerase to the promoter. Now a genome-wide sequencing study of more than 10,000 enhancers that respond to electrical activity in neurons shows that the regulatory process also brings the polymerase to the enhancers themselves, where it transcribes non-coding RNAs. This 'enhancer RNA' (eRNA) synthesis occurs only at enhancers actively engaged in promoting mRNA synthesis from a promoter. The results suggest that at least in the brain, enhancers play a more active 'promoter-like' role in regulating gene expression than previously appreciated.