Abstract

Members of the α/β-hydrolase domain (ABHD) protein family have emerged as novel potential regulators of lipid metabolism and signal transduction . In this study, two ABHD genes (ABHD4 and ABHD5, named Ci ABHD4 and Ci ABHD5) were identified and characterized in Ctenopharyngodon idella . The ORF of Ci ABHD4 cDNA was 1101 bp (MK645600), and encode 366 amino acids. The ORF of Ci ABHD5 cDNA was 1035 bp (KP325482), and encode 344 amino acids. Phylogenetic analysis showed that the Ci ABHD4 and Ci ABHD5 were all closely clustered with the fish ABHD4 and ABHD5 subcluster. Both Ci ABHD4 and Ci ABHD5 in Ctenopharyngodon idella were highly expressed in liver. Moreover, we compared the effect of saturated fatty acids (palmitic acid, PA), monounsaturated fatty acids (oleic acid, OA) and polyunsaturated fatty acids (Docosahexaenoic acid, DHA) on Ci ABHD4 and Ci ABHD5 expression, and found that PA significantly induce expression of Ci ABHD4 and Ci ABHD5, but OA and DHA significantly increased lipid droplet (LD) formation in L8824 and CIK cells. Furthermore, inhibition of ER stress or IRE1α significantly alleviated Ci ABHD4 and Ci ABHD5 expression induced by PA, indicating that ER stress or IRE1α pathway was involved in PA-induced Ci ABHD4 and Ci ABHD5 expression. Subcellular localization analysis indicated that CiABHD4 and CiABHD5 proteins were differentially distributed in COS7 cells. In addition, the overexpression of Ci ABHD4 or Ci ABHD5 increased the significant expression of ATGL genes, and decrease lipid accumulation induced by the OA/PA combination in COS7 cells. We also demonstrated that Ci ABHD5 does not directly interact with ATGL by Co-IP assay. Taken together, our results suggested that Ci ABHD4 and Ci ABHD5 were induced by PA through ER stress, and play essential roles in lipid accumulation by regulating ATGL expression in Ctenopharyngodon idella .