Emerging roles of transcriptional enhancers in chromatin looping and promoter-proximal pausing of RNA polymerase II

Initiation and regulation of transcription by RNA polymerase II (RNAPII) in eukaryotes rely on the transcriptional regulatory elements. Promoters and enhancers share similar architectures and functions, and the prevailing view is that they can initiate bidirectional transcription. We summarize functional roles of enhancer transcription and possible mechanisms in enhancer-promoter communication. We discuss the potential roles of enhancer RNAs (eRNAs) in early elongation and highlight that transcriptional enhancers might modulate the release of paused RNAPII via 3D chromatin looping. Emerging evidence suggests that transcriptional enhancers regulate the promoter-proximal pausing of RNAPII, a key rate-limiting step required for productive elongation.