Poster Abstract: ROW Binds to Nucleosomes to Limit the Spreading of RNAPII and Z4

Rebecca Wright, PhD Student, University of Nebraska Medical Center

Abstract

Transcription is regulated by a myriad of factors, including the HP1c transcription complex. This complex is comprised of four member proteins in Drosophila melanogaster cells, including Relative of Woc (ROW). The HP1c complex is known to bind to euchromatic regions and is associated with RNAPII pausing. A contributing factor in RNAPII pausing is the presence of a well-positioned +1 nucleosome. Nucleosomes are a physical barrier to transcription that need to be overcome by the transcription complex in order for productive elongation to occur. It has been suggested that the HP1c complex serves as a bridge between RNAPII and the FACT complex, which is a histone chaperone that assist RNAPII in bypassing nucleosomes and continue productive elongation. Intriguingly, our preliminary data demonstrates that ROW binds adjacent to the HP1c complex, rather than at the same site as other member proteins. Our data shows that ROW-depleted chromatin has increased and broader RNAPII signal at the TSS of genes with ROW. Further analysis reveals that in ROW-depleted chromatin, RNAPII only extends to the boundary of where ROW was, indicating that is potentially being stopped by the presence of a nucleosome. The results of our study support the hypothesis that ROW binds to nucleosomes to assist other HP1c complex members in regulating transcriptional activity.