Rna Polymerase Ii-Binding Aptamers In Human Acro1 Satellites Disrupt Transcriptionin Cis

Transcription elongation is a highly regulated process affected by many proteins, RNAs and the underlying DNA. Here we show that the nascent RNA can interfere with transcription in human cells, extending our previous findings from bacteria and yeast. We identified a variety of Pol II-binding aptamers (RAPs), prominent in repeat elements such as ACRO1 satellites, LINE1 retrotransposons and CA simple repeats, and also in several protein-coding genes. ACRO1 repeat, when translatedin silico, exhibits similar to 50% identity with the Pol II CTD sequence. Taken together with the observation that proteins in general tend to interact with RNAs similar to their cognate mRNAs, this suggests a mechanism for RAP binding. Using a reporter construct, we show that ACRO1 potently inhibits Pol II elongationin cis. We propose a novel mode of transcriptional regulation in humans, in which the nascent RNA binds Pol II to silence its own expression.