Drosophila FACT Regulates Promoter Proximal Pol II Pausing and Chromatin Architecture [ChIP-seq]

The highly conserved histone chaperone FACT (Facilitates Chromatin Transcription) is thought to contribute to the disassembly and reassembly of nucleosomes in the wake of RNA Polymerase II (Pol II) passage through chromatin. However, FACT’s roles in chromatin biology and transcriptional regulation in vivo in higher eukaryotes are not well understood. Here, we report that depletion of FACT leads to a reduction in the duration of promoter-proximal pausing by Pol II in Drosophila S2 cells. In addition, FACT depletion leads to a modest decrease in the occupancy of histone H3,  and to decrease in occupancy of histone H2A.v in promoter-proximal nucleosomes. Finally, we observed a dramatic 5’ to 3’ repositioning of the co-transcriptionally deposited histone modifications H3K4me3 and H3K36me3 in the FACT depleted cells. Taken together, our findings are consistent with the model that FACT contributes to the interplay between chromatin architecture and control of Pol II promoter-proximal pausing. Genome-wide examination of H3K36me3, H3K4me3, H3, H2Av, total RNA, transcriptionally engaged Pol II, and Pol II half-life in Drosophila melanogaster S2 cells depleted of FACT compared to control cells.