Identification of cis-regulatory elements provides insights into tissue-specific gene regulation in the sheep genome

Annotation of regulatory elements is essential for understanding mechanisms underlying gene regulation, particularly tissue-specific regulation in human and animals. Here, we characterize 274,682 enhancers and 25,975 promoters across 24 tissues from an adult female sheep using ChIP-seq, ATAC-seq, CAGE-seq, RRBS, WGBS, and RNA-seq. We identify seven neural development-related genes with over 10 enhancers in brain tissues, highlighting the role of tissue-specific regulation. Cis-regulatory enhancer-promoter combinations provide insights into tissue-specific enhancers, such as the cerebellum-specific enhancer (chr15: 57390520-57390685) regulating BDNF, which is expressed in both the cerebellum and cerebral cortex. Comparative analysis of enhancer-promoter combinations in human, mouse, pig, cattle, and sheep reveals ruminant-specific pathways, including pentose catabolism and long-chain fatty acid import regulation. A milk fat yield quantitative trait locus (QTL) identified within an enhancer interacts with the fat metabolism-related gene COMMD1, and a birth weight-associated QTL detected within a cerebellum-specific enhancer regulates XKR4. This study provides a robust framework for exploring cis-regulatory mechanisms and tissue-specific regulation, advancing the functional annotation of the sheep reference genome. Annotating regulatory elements in domestic animal genomes is important to understand the mechanisms underlying gene regulation. Here, the authors use multi-omics data from sheep to map regulatory elements in the sheep genome.