question: What are the eRNA-producing centers (EPCs)?
answer: Active enhancers in mammals produce enhancer RNAs (eRNAs) that are bidirectionally transcribed, unspliced, and unstable. Enhancer regions are also enriched with long noncoding RNA (lncRNA) transcripts, which are typically spliced and substantially more stable. DNase hypersensitive sites with evidence of bidirectional transcription are called eRNA-producing centers (EPCs). EPCs found very close to transcription start sites of lncRNAs exhibit attributes of both enhancers and promoters, including distinctive DNA motifs and a characteristic chromatin landscape. These EPCs are associated with higher enhancer activity, driven at least in part by the presence of conserved, directional splicing signals that promote lncRNA production, pointing at a causal role of lncRNA processing in enhancer activity.