The super-enhancer repertoire in porcine liver

The transcriptional initiation of genes is inextricably bound with the functions of cis-regulatory sequences. The pig is one of the most important livestock species and an ideal animal model for biomedical studies. At the same time, the liver is a critical organ with diverse and complex metabolic functions. Here, we performed Cleavage Under Targets and Tagmentation (CUT&Tag) coupled with high-throughput sequencing to profile the chromatin landscape of histone H3 lysine 27 acetylation (H3K27ac), histone H3 lysine 4 monomethylation (H3K4me1), and CCAAT enhancer-binding protein β (C-EBPβ) in the 70-d-old porcine liver, compared the different profiles among the three markers and their associated stitched-enhancers by stitching and sorting the peaks within 12.5 kb (Pott and Lieb, 2015) and generated the porcine liver-specific super-enhancers (SEs) by the combination of three markers. Compared to typical enhancers (TEs) and other stitched-enhancers, liver-specific SEs showed a higher density of cis-motifs and SNPs, which may recruit more tissue-specific vital TFs. The expression profiles in fetal and 70-d-old pigs proved that a large proportion of SE-associated genes were up-regulated and were more related to hepatic metabolisms and detoxification pathways. Our results illustrated the difference and connection among promoter and enhancer markers, identified the features of liver SEs and their associated genes, and provided novel insight into cis-element identification, function, and liver transcriptional regulation.