Effects of abhydrolase domain containing 5 gene (ABHD5) expression and variations on chicken fat metabolism.

Abhydrolase domain containing 5 gene (ABHD5), also known as comparative gene identification 58 (CGI-58), is a member of the α/β-hydrolase family as a protein cofactor of ATGL stimulating its triacylglycerol hydrolase activity. In this study, we aim to characterize the expression and variations of ABHD5 and to study their functions in chicken fat metabolism. We compared the ABHD5 expression level in various tissues and under different nutrition conditions, identified the variations of ABHD5, and associated them with production traits in an F2 resource population of chickens. Overexpression analysis with two different genotypes and siRNA interfering analysis of ABHD5 were performed in chicken preadipocytes. Chicken ABDH5 was expressed widely and most predominantly in adipose tissue. Five SNPs of the ABHD5 gene were identified and genotyped in the F2 resource population. The c.490C > T SNP was associated with subcutaneous fat thickness (P < 0.01), carcass weight (P < 0.05), body weight (P < 0.05), shank diameter (P < 0.05), and shank length (P < 0.05). The c.423T > C SNP was also associated with chicken body weight (P < 0.05) and shank diameter (P < 0.05). In chicken preadipocytes, overexpression of wild type ABDH5 did not affect the mRNA level of ATGL (adipose triglyceride lipase) but markedly decreased (P < 0.05) the TG (triglyceride) content of the cell, whereas overexpression of mutation type ABHD5 did not affect either ATGL expression or TG content of the cell. The expression of ATGL and TG content of the cell were decreased (P < 0.05) after ABHD5 knockdown in preadipocytes. The mRNA level of ABHD5 was regulated by both feeding and fasting, and by consumption of a high fat diet. It was increased greatly by fasting (P < 0.05) and was returned to control levels after re-feeding in the adipose tissues, and down-regulated in abdominal fat (P < 0.05) and the liver (P < 0.01) of chickens with a high fat diet. These results suggest that expression and variations of ABHD5 may affect fat metabolism through regulating the activity of ATGL in chickens.