The fission yeast CENP-B protein Abp1 prevents pervasive transcription of repetitive DNA elements

Abstract

<p class="first" id="P1">It is well established that eukaryotic genomes are pervasively transcribed producing cryptic unstable transcripts (CUTs). However, the mechanisms regulating pervasive transcription are not well understood. Here, we report that the fission yeast CENP-B homologue Abp1 plays an important role in preventing pervasive transcription. We show that loss of <i>abp1</i> results in the accumulation of CUTs, which are targeted for degradation by the exosome pathway. These CUTs originate from different types of genomic features, but the highest increase corresponds to <i>Tf2</i> retrotransposons and rDNA repeats, where they map along the entire elements. In the absence of <i>abp1,</i> increased RNAPII-Ser5P occupancy is observed throughout the <i>Tf2</i> coding region and, unexpectedly, RNAPII-Ser5P is enriched at rDNA repeats. Loss of <i>abp1</i> also results in <i>Tf2</i> derepression and increased nucleolus size. Altogether these results suggest that Abp1 prevents pervasive RNAPII transcription of repetitive DNA elements (ie, <i>Tf2</i> and rDNA repeats) from internal cryptic sites. </p>