Genome-Wide Profiling of H3K27ac in Tianzhu White Yak Skin at the Anagen and Telogen Stages

The Tianzhu white yak, native to Gansu Province, China, is valued for its white coat and fibre traits. Its hair follicles undergo pronounced seasonal cycling, but the associated epigenomic regulation remains poorly understood. We profiled H3K27ac in skin samples collected during anagen and telogen using Cleavage Under Targets and Tagmentation (CUT&Tag) and integrated these data with RNA sequencing. We identified 14,496 differentially enriched regions, including 5618 with increased and 8878 with decreased H3K27ac enrichment during anagen. Associated genes were enriched in pathways governing follicle activation, epithelial remodelling and tissue homeostasis, including Wnt, PI3K-AKT, MAPK and TGF-beta signalling. Putative targets of anagen-specific super-enhancers were enriched in PI3K-AKT and Notch pathways. Motif analysis revealed enrichment of binding motifs for transcription factors implicated in hair follicle biology, including LEF1, LHX2, FOXN1 and GATA3, whereas FOSL2 and FOS::JUNB motifs were preferentially enriched in anagen-gain regions. Integrative CUT&Tag and RNA-seq analysis identified 765 genes showing concordant changes in H3K27ac enrichment and transcript abundance between anagen and telogen, including candidate hair follicle regulators such as FGF5, PDGFRA, TCF7 and SMAD7. These findings characterize phase-associated regulatory landscapes and identify candidate regulatory elements and genes potentially involved in hair cycling and fibre traits.