Studying RNA#8211;DNA interactome by Red-C identifies noncoding RNAs associated with repressed chromatin compartment and reveals transcription dynamics

Abstract

Non-coding RNAs (ncRNAs) participate in various biological processes, including regulating transcription and sustaining genome 3D organization. Here, we present a method termed Red-C that exploits proximity ligation to identify contacts with the genome for all RNA molecules present in the nucleus. Using Red-C, we uncovered the RNA-DNA interactome of human K562 cells and identified hundreds of ncRNAs enriched in active or repressed chromatin, including previously undescribed RNAs. We found two microRNAs--MIR3648 and MIR3687 transcribed from the rRNA locus--that are associated with inactive chromatin genome wide. These miRNAs favor bulk heterochromatin over Polycomb-repressed chromatin and interact preferentially with late-replicating genomic regions. Analysis of the RNA-DNA interactome also allowed us to trace the kinetics of messenger RNA production. Our data support the model of co-transcriptional intron splicing, but not the hypothesis of the circularization of actively transcribed genes.