title: Cloning and Characterization of Lxr and Srebp1, and Their Potential Roles in Regulation of LC-PUFA Biosynthesis in Rabbitfish Siganus canaliculatus.
abstract: Rabbitfish Siganus canaliculatus was the first marine teleost demonstrated to have the ability to biosynthesize C20-22 long-chain polyunsaturated fatty acid (LC-PUFA) from C18 PUFA precursors, which is generally absent or low in marine teleosts. Thus, understanding the molecular basis of LC-PUFA biosynthesis in rabbitfish will contribute to efforts aimed at optimizing LC-PUFA biosynthesis in teleosts, especially marine species. In the present study, the importance of the transcription factors liver X receptor (Lxr) and sterol regulatory element-binding protein 1 (Srebp1) in regulation of LC-PUFA biosynthesis in rabbitfish was investigated. First, full-length cDNA of Lxr and Srebp1 were cloned and characterized. The Lxr mRNA displayed a ubiquitous tissue expression pattern while Srebp1 was highly expressed in eyes, brain and intestine. In rabbitfish primary hepatocytes treated with Lxr agonist T0901317, the expression of Lxr and Srebp1 was activated, accompanied by elevated mRNA levels of Δ4 and Δ6/Δ5 fatty acyl desaturase (Fad), key enzymes of LC-PUFA biosynthesis, as well as peroxisome proliferator-activated receptor γ (PPARγ). In addition, Srebp1 displayed higher expression levels in liver of rabbitfish fed a vegetable oil diet or reared at 10 ppt salinity, which were conditions reported to increase the liver expression of Δ4 and Δ6/Δ5 Fad and LC-PUFA biosynthetic ability, than fish fed a fish oil diet or reared at 32 ppt, respectively. These results suggested that Lxr and Srebp1 are involved in regulation of LC-PUFA biosynthesis probably by promoting the expression of two Fad in rabbitfish liver, which, to our knowledge, is the first report in marine teleosts.
authors.affiliation: Marine Biology Institute and Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, Guangdong, China.
authors.forename: Qinghao
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Marine Biology Institute and Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, Guangdong, China.
authors.forename: Cuihong
authors.initials: C
authors.lastname: You
authors.affiliation: Marine Biology Institute and Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, Guangdong, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Liu
authors.affiliation: Marine Biology Institute and Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, Guangdong, China.
authors.forename: Wendi
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Marine Biology Institute and Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, Guangdong, China.
authors.forename: Shuqi
authors.initials: S
authors.lastname: Wang
authors.affiliation: Marine Biology Institute and Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, Guangdong, China.
authors.forename: Dizhi
authors.initials: D
authors.lastname: Xie
authors.affiliation: Institute of Aquaculture, University of Stirling, Stirling, Scotland, UK.
authors.forename: Óscar
authors.initials: Ó
authors.lastname: Monroig
authors.affiliation: Institute of Aquaculture, University of Stirling, Stirling, Scotland, UK.
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Tocher
authors.affiliation: Marine Biology Institute and Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, Guangdong, China. yyli@stu.edu.cn.
authors.forename: Yuanyou
authors.initials: Y
authors.lastname: Li
mesh_terms: D000818:Animals; D003001:Cloning, Molecular / Q000379:methods*; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis*; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005786:Gene Expression Regulation; D000071518:Liver X Receptors / Q000235:genetics* / Q000378:metabolism; D009928:Organ Specificity; D010473:Perciformes / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D051780:Sterol Regulatory Element Binding Protein 1 / Q000235:genetics* / Q000378:metabolism
chemical_list: D005231:Fatty Acids, Unsaturated; D029941:Fish Proteins; D000071518:Liver X Receptors; D051780:Sterol Regulatory Element Binding Protein 1
keywords: Elovl; Fad; LC-PUFA biosynthesis; Lxr; Rabbitfish Siganus canaliculatus; Srebp1