Integrator mediates the biogenesis of enhancer RNAs

Integrator is a multi-subunit complex stably associated with the C-terminal domain (CTD) of RNA polymerase II (RNAPII) (1). Integrator is endowed with a core catalytic RNA endonuclease activity, which is required for the 3′-end processing of non-polyadenylated RNAPII-dependent uridylate-rich small nuclear RNA genes (UsnRNAs) (1). Here, we examined the requirement of Integrator in the biogenesis of transcripts derived from distal regulatory elements (enhancers) involved in tissue- and temporal-specific regulation of gene expression (2–5). Integrator is recruited to enhancers and super-enhancers in a stimulus-dependent manner. Functional depletion of Integrator subunits diminishes the signal-dependent induction of eRNAs and abrogates the stimulus-induced enhancer-promoter chromatin looping. Global nuclear run-on and RNAPII profiling reveals a role for Integrator in 3′-end cleavage of eRNAs primary transcripts leading to transcriptional termination. In the absence of Integrator, eRNAs remain bound to RNAPII and their primary transcripts accumulates. Importantly, the induction of eRNAs and gene expression responsiveness requires the catalytic activity of Integrator complex. We propose a role for Integrator in biogenesis of eRNAs and enhancer function in metazoans.