Regulation of Pol II pausing is involved in daily transcription in the mouse livers in the mouse liver

Purpose: We used ChIP-seq to analyze daily transcription and regulation of Pol II pausing within the mouse liver. Methods: Livers of young mice were processed for Pol II and Nelf-A ChIP-seq at 4-h interval across the day. The binding pattern was analyzed by MACS. Tag pileup within promoter and gene body regions were also obtained to calculate Pol II TR. Results: We obtained > 10 million high quality sequencing reads per time points per sample after quality control and alignments. MACS identified nearly 10,000 Pol II peaks genomewide throughout the day. Nelf-A peaks varied from a few hundreds to 10,000 across the day. A genomewide Nelf-A binding rhythm was evident. We also quantitated bindings within the TSS region and/or gene body and analyzed the quantitation results with ARSER for rhythm detection. We found Pol II binding within the TSS region and gene body show discordant changes. While most genes had peak TSS Pol II binding around dawn, Pol II binding within the gene body showed more scattered distribution, with two peaks around dawn and dusk, respectively. Pol II traveling ratio also showed daily changes, with most genes having a higher TR around dawn. Conclusions: Our study revealed discordant Pol II rhythms in the TSS region and within the gene body, and indicated that Pol II initiation and pause release could have distinct roles in the generation of transcription rhythms within the mouse liver. Mouse liver chromatin was prepared at 4-h interval across the day and used in ChIP-seq with Pol II, Nelf-A and Tbp antibodies.