DNA methylation landscape of 16 canine somatic tissues by methylation-sensitive restriction enzyme-based next generation sequencing.

DNA methylation plays important functions in gene expression regulation that is involved in individual development and various diseases. DNA methylation has been well studied in human and model organisms, but only limited data exist in companion animals like dog. Using methylation-sensitive restriction enzyme-based next generation sequencing (Canine DREAM), we obtained canine DNA methylation maps of 16 somatic tissues from two dogs. In total, we evaluated 130,861 CpG sites. The majority of CpG sites were either highly methylated (> 70%, 52.5-64.6% of all CpG sites analyzed) or unmethylated (< 30%, 22.5-28.0% of all CpG sites analyzed) which are methylation patterns similar to other species. The overall methylation status of CpG sites across the 32 methylomes were remarkably similar. However, the tissue types were clearly defined by principle component analysis and hierarchical clustering analysis with DNA methylome. We found 6416 CpG sites located closely at promoter region of genes and inverse correlation between DNA methylation and gene expression of these genes. Our study provides basic dataset for DNA methylation profiles in dogs.