CTCF blocks anti-sense transcription initiation at divergent gene promoters [PRO-Seq]

Transcription is typically divergent, initiating at closely spaced oppositely oriented core promoters to produce sense and unstable upstream antisense transcripts (uasTrx). How antisense transcription is regulated and coordinated with sense transcription is largely unknown. Here by combining acute degradation of the multi-functional transcription factor CTCF and nascent transcription measurements, we find that CTCF specifically suppresses antisense but not sense transcription at hundreds of divergent promoters, the great majority of which bear proximal CTCF binding sites. Genome editing, chromatin conformation studies and 5' transcript mapping revealed that CTCF directly suppresses uasTrx initiation in manner independent of its chromatin architectural function. Primary transcript RNA FISH revealed co-bursting of sense and anti-sense transcripts is disfavored, suggesting CTCF-regulated competition for transcription initiation. In sum, CTCF shapes the noncoding transcriptional landscape by suppressing upstream antisense transcription. Overall design: Transient endogenous CTCF/Nipbl depletion coupled with genome wide RNA Pol II binding profiling (ChIP-seq) and nascent transcription quantification (PRO-seq)