Identification of the long-chain acyl-CoA synthetase 3 gene from mud crab Scylla paramamosain, and examination of its role in lipid metabolism

Several studies have indicated the importance of long-chain acyl-CoA synthetase family member 3 (Acsl3) in mammalian lipid metabolism, but its potential function in decapod crustaceans with an open circulatory system is still unclear. In the present study, an acsl3 gene was identified and characterized for the first time from mud crab Scylla paramamosain , a typical decapod crustacean species. The coding sequence of the acsl3 gene was 2121 bp and encodes a protein of 706 amino acid residues that possesses highly conserved ATP-AMP and fatty acyl-CoA synthetase signature motifs. Relative expression levels of a csl3 were higher in tissues with active lipid metabolism such as hepatopancreas, intestine, and gonad, and increased in the latter as the ovaries matured in female crabs. Functional characterization verified that the Acsl3 protein promoted exogenous fatty acid uptake and lipid accumulation, and restored the growth of Saccharomyces cerevisiae YB525 ( faa1 Δ faa4 Δ). Culturing the transformed YB525 in media containing different fatty acids showed that the mud crab Acsl3 protein exhibited a strong substrate preference for 22:6n-3, followed by 14:0, 12:0 and 18:3n-3. Knockdown of Acsl3 through RNA interference by injection of mud crab with acsl3 -dsRNA significantly reduced lipid deposition and the contents of total saturated fatty acids and n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA), especially 22:6n-3, in hepatopancreas. The expression levels of key genes associated with lipogenesis ( srebp1 , pparγ , c/ebpγ , dgat1 and acc ) in hepatopancreas were also significantly downregulated in crabs after treatment with acsl3 -dsRNA. The data indicates that Acsl3 has important roles in fatty acid absorption, lipid deposition, and especially LC-PUFA accumulation in mud crab, providing further insight into our understanding the mechanisms of regulating LC-PUFA content in decapod crustacean tissues. • Acsl3 gene is firstly cloned and identified from decapod crustacean S. paramamosain . • Acsl3 gene is abundantly expressed in active lipid metabolism tissues hepatopancreas, intestine and gonads. • Acsl3 displays a strong substrate preference for n-3 PUFA, especially DHA and ALA. • Acsl3 plays an important role in lipid accumulation and LC-PUFA deposition of mud crab.