Methylation differences and expression profiles of the caprine DIO3 gene.

DIO3 gene encoding type 3 iodothyronine deiodinase is an imprinted gene, located in the DLK1-DIO3 (delta-like 1 homolog-type 3 iodothyronine deiodinase) imprinted domain, and is potentially involved in degrading excessive amounts of thyroid hormone to protect embryogenesis. However, the underlying regulatory mechanism of the imprinted DIO3 gene expression during fetal and neonatal development in goats has not been elucidated. In this study, we explored the DNA methylation patterns of the caprine DIO3 intragenic CpG island and quantified gene expression level in six tissues from Chinese Nanjiang Yellow 3-day old kids. The expression of the DIO3 gene was determined using quantitative reverse transcription-polymerase chain reactions (qRT-PCRs), while the identification of methylation patterns was determined using bisulfite-sequencing PCRs. Modest, and non-significant (P > 0.05), methylation patterns were noted for the DIO3 CpG island methylation in the brain, heart, liver, kidney, lung, and longissimus dorsi tissues (ranging from 26.48 to 34.92%). The expression level of the DIO3 mRNA was significantly higher (P < 0.05) in the liver tissue than in the other five tissues. Pearson's correlation analysis revealed that there was no significant relationship between methylation and gene expression (P > 0.05), which indicated that the expression of the caprine DIO3 gene was likely modified by other regulatory elements. This study identified DNA methylation and expression patterns of the DIO3 gene in goats and provided insights into further regulatory mechanisms of expression and imprinting in the DLK1-DIO3 domain.