DNA methylation pattern is associated with elevated expression of DGAT2 in hybrid tilapia

Abstract

Lipid metabolism is a key biological process involving the synthesis and degradation of lipids in organisms. In the liver, triglyceride (TG) synthesis mediates the storage of fats for energy, which is catalysed by diacylglycerol acyltransferase-2 (DGAT2). Herein, we compared TG-related indexes in serum from Nile tilapia (Oreochromis niloticus), blue tilapia (O. aureus) and hybrid offspring (Nile tilapia ♀ × blue tilapia ♂). The results showed that serum TG levels were significantly higher in the hybrid tilapia (6.95 ± 1.48 mmol/L) than that in blue tilapia (4.39 ± 1.02 mmol/L). Tissue distribution analysis suggested that DGAT2 was mainly expressed in the liver and muscle. Furthermore, hybrid tilapia exhibited higher mRNA expression of DGAT2 in the liver than the parents. Additionally, the allelic gene expression assay indicated that the alleles of DGAT2 gene from the two parental species were expressed at equal levels. To elucidate the epigenetic regulation of DGAT2 gene expression, the DNA methylation levels at the putative promoter region of DGAT2 in hybrid tilapia and its parents were compared. We found lower DNA methylation levels at the putative promoter region of DGAT2 in hybrid tilapia as compared to the paternal species in liver. DNA methylation levels in the putative promoter region were negatively correlated with DGTA2 expression in tilapia. Three CpG sites were significantly correlated with DGAT2 expression in tilapia. Overall, the present evidence suggests that DNA methylation is associated with the elevated expression of DGAT2 in hybrid tilapia. These results provide new evidence for epigenetic regulation of genes in hybrids, which may aid to understanding of heterosis for fish hybridization breeding and superiorities of nutrient utilization in hybrids.