Enhancer RNAs add a crucial regulatory layer to the genome.
Enhancer RNA or eRNA are RNAs transcribed by RNA polymerase II (RNAPII) from the domain of transcription enhancers. eRNAs are a class of short non-coding RNAs, 50 to 2,000 nucleotides in length, transcribed from DNA enhancer regions. eRNAs stimulate gene expression, but the precise mechanisms of how they function remain unclear.
Enhancers are intergenic DNA elements regulating the transcription of target genes in response to signaling pathways by interacting with promotors over large genomic distances. Enhancers contain binding sites for transcription factors promoting RNA polymerase II (RNAPII) recruitment and activation. Also, enhancers carry unique epigenetic marks that distinguish them from promoters.
Additionally, these regulatory elements have an open chromatin conformation that increases accessibility to transcription factors and RNAPII. Enhancers are transcribed bi-directionally into eRNAs.
{Kim et al. 2010}.