title: Molecular Cloning, Functional Characterization and Nutritional Regulation of the Putative Elongase Elovl5 in the Orange-Spotted Grouper (Epinephelus coioides).
abstract: The enzymes involved in the biosynthesis of long-chain polyunsaturated fatty acids (LC-PUFAs) are widely studied in fish species, as fish are the main source of n-3 LC-PUFAs for human beings. In the present study, a putative gene for elovl5, which encodes a key enzyme involved in LC-PUFA synthesis, was cloned and functionally characterized, and its transcription in response to dietary n-3 LC-PUFA exposure was investigated. Moreover, cell transfection and luciferase assays were used to explore the mechanism underlying the regulation of elovl5. The full-length cDNA of elovl5 was 1242 bp (excluding the polyA tail), including an 885 bp coding region encoding a 295 amino acid protein that possesses all of the characteristic features of elovl proteins. Functional characterization of heterologously expressed grouper Elovl5 indicated that it effectively elongates both C18 (18:2n-6, 18:3n-3, 18:3n-6 and 18:4n-3) and C20 (20:4n-6 and C20:5n-3) PUFAs, but not the C22 substrates. The expression of elovl5 was significantly affected by dietary n-3 LC-PUFA exposure: a high n-3 LC-PUFA level repressed the expression of elovl5 by slightly down-regulating the expression of sterol regulatory element-binding protein (SREBP)-1 and liver X receptor (LXR) α, which are major regulators of hepatic lipid metabolism. Promoter studies showed that grouper elovl5 reporter activity was induced by over-expression of LXRα but not SREBP-1. This finding suggests that elovl5 is a direct target of LXRα, which is involved in the biosynthesis of PUFAs via transcriptional regulation of elovl5. These findings may contribute to a further understanding of the mechanism underlying the regulation of LC-PUFA biosynthesis in marine fish species.
authors.affiliation: Key Laboratory of Aquaculture Nutrition and Feed, Ministry of Agriculture, Ocean University of China, Qingdao 266003, People's Republic of China.|Key Laboratory of Mariculture, Ministry Education of China, Ocean University of China, Qingdao 266003, People's Republic of China.|Laboratory for Marine Fisheries and Aquaculture, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
authors.forename: Songlin
authors.initials: S
authors.lastname: Li
authors.affiliation: Key Laboratory of Aquaculture Nutrition and Feed, Ministry of Agriculture, Ocean University of China, Qingdao 266003, People's Republic of China.|Key Laboratory of Mariculture, Ministry Education of China, Ocean University of China, Qingdao 266003, People's Republic of China.|Laboratory for Marine Fisheries and Aquaculture, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
authors.forename: Yuhui
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Key Laboratory of Aquaculture Nutrition and Feed, Ministry of Agriculture, Ocean University of China, Qingdao 266003, People's Republic of China.|Key Laboratory of Mariculture, Ministry Education of China, Ocean University of China, Qingdao 266003, People's Republic of China.|Laboratory for Marine Fisheries and Aquaculture, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
authors.forename: Tianjiao
authors.initials: T
authors.lastname: Wang
authors.affiliation: Key Laboratory of Aquaculture Nutrition and Feed, Ministry of Agriculture, Ocean University of China, Qingdao 266003, People's Republic of China.|Key Laboratory of Mariculture, Ministry Education of China, Ocean University of China, Qingdao 266003, People's Republic of China.|Laboratory for Marine Fisheries and Aquaculture, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.affiliation: Key Laboratory of Aquaculture Nutrition and Feed, Ministry of Agriculture, Ocean University of China, Qingdao 266003, People's Republic of China.|Key Laboratory of Mariculture, Ministry Education of China, Ocean University of China, Qingdao 266003, People's Republic of China.|Laboratory for Marine Fisheries and Aquaculture, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
authors.forename: Mingzhu
authors.initials: M
authors.lastname: Li
authors.affiliation: Key Laboratory of Aquaculture Nutrition and Feed, Ministry of Agriculture, Ocean University of China, Qingdao 266003, People's Republic of China.|Key Laboratory of Mariculture, Ministry Education of China, Ocean University of China, Qingdao 266003, People's Republic of China.|Laboratory for Marine Fisheries and Aquaculture, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
authors.forename: Kangsen
authors.initials: K
authors.lastname: Mai
authors.affiliation: Key Laboratory of Aquaculture Nutrition and Feed, Ministry of Agriculture, Ocean University of China, Qingdao 266003, People's Republic of China.|Key Laboratory of Mariculture, Ministry Education of China, Ocean University of China, Qingdao 266003, People's Republic of China.|Laboratory for Marine Fisheries and Aquaculture, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
authors.forename: Qinghui
authors.initials: Q
authors.lastname: Ai
mesh_terms: D000123:Acetyltransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001492:Bass / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D008969:Molecular Sequence Data; D010802:Phylogeny
chemical_list: D005231:Fatty Acids, Unsaturated; D000123:Acetyltransferases