Exploring Tissue- and Sex-Specific DNA Methylation in Cattle Using a Pan-Mammalian Infinium Array.

DNA methylation is crucial in gene expression regulation and tissue differentiation in livestock. However, genome-wide methylation patterns among tissues remain underexplored in cattle, one of the world's most important farm animals. This study investigates sex- and tissue-specific DNA methylation in cattle using CpG site methylation data generated by an Infinium DNA Methylation array (HorvathMammalMethyl-Chip40) across seven tissues. Our analysis revealed significant tissue-specific methylation differences, with reproductive tissues/cells, such as the sperm, exhibiting distinct profiles compared to somatic tissues like hair and blood. Principal component analysis (PCA) highlighted tissue differentiation as the primary driver of methylation variability. We also identified 222 CpG sites with significant sex-based methylation differences, particularly on the X chromosome, suggesting the potential epigenetic regulation of sex-specific traits. The Gene Ontology (GO) enrichment analysis indicated that these methylation patterns may influence biological processes such as epithelial cell proliferation and blood vessel remodeling. Overall, this study provides important insights into sex- and tissue-specific epigenetic regulation in cattle, with implications for improving livestock breeding strategies through integrating epigenetic data.