title: miR-17 is involved in the regulation of LC-PUFA biosynthesis in vertebrates: effects on liver expression of a fatty acyl desaturase in the marine teleost Siganus canaliculatus.
abstract: Biosynthesis in vertebrates of long-chain polyunsaturated fatty acids (LC-PUFA) such as arachidonic (ARA; 20:4n-6), eicosapentaenoic (EPA; 20:5n-3) and docosahexaenoic (DHA; 22:6n-3) acids requires the catalysis by fatty acyl desaturases (Fads). A vertebrate Fad with Δ4 activity catalyzing the direct conversion of 22:5n-3 to DHA was discovered in the marine teleost rabbitfish Siganus canaliculatus. Recent studies in vertebrates have shown that miRNAs may participate in the regulation of lipid metabolism at post-transcription level. However, their roles in LC-PUFA biosynthesis were not known. In the present study, in silico analysis predicts that the rabbitfish Δ4 Fad may be a target of miR-17 and thus we cloned miR-17, which is located at the forepart of the miR-17-92 cluster. Dual luciferase reporter assays demonstrated that miR-17 targeted the 3'UTR of Δ4 Fad directly. Furthermore, the expression level of miR-17 displayed an inverse pattern with that of Δ4 Fad mRNA in gill, liver and eyes, and also the Δ4 Fad protein quantity in rabbitfish liver. Incubation of rabbitfish primary hepatocytes with linoleic acid (LA; 18:2n-6), α-linolenic acid (LNA; 18:3n-3), EPA or DHA showed differential effects on miR-17, Δ4 Fad and Δ6/Δ5 Fad expression. LNA promoted the expression of miR-17 and Δ6/Δ5 Fad, but suppressed the expression of Δ4 Fad. In contrast, LA and EPA decreased the expression of miR-17 and Δ6/Δ5 Fad, but had no effect on Δ4 Fad. However, all the above were down-regulated by DHA. These data indicate that miR-17 was involved in the regulation of LC-PUFA biosynthesis in rabbitfish liver by targeting Δ4 Fad.
authors.affiliation: Marine Biology Institute & 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 & Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, Guangdong, China.
authors.forename: Dizhi
authors.initials: D
authors.lastname: Xie
authors.affiliation: Marine Biology Institute & 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 & Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, Guangdong, China.
authors.forename: Cuihong
authors.initials: C
authors.lastname: You
authors.affiliation: Institute of Aquaculture, University of Stirling, Stirling, Scotland, UK.
authors.forename: Oscar
authors.initials: O
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 & Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, Guangdong, China. Electronic address: yyli@stu.edu.cn.
authors.forename: Yuanyou
authors.initials: Y
authors.lastname: Li
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D001483:Base Sequence; D005123:Eye / Q000378:metabolism; D044943:Fatty Acid Desaturases / Q000235:genetics / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis* / Q000494:pharmacology; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D005880:Gills / Q000378:metabolism; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D050356:Lipid Metabolism / Q000235:genetics; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010473:Perciformes / Q000235:genetics / Q000378:metabolism*; D061251:Primary Cell Culture; D015398:Signal Transduction
chemical_list: D020413:3' Untranslated Regions; D005231:Fatty Acids, Unsaturated; D007527:Isoenzymes; D035683:MicroRNAs; D008156:Luciferases; D044943:Fatty Acid Desaturases
keywords: LC-PUFA biosynthesis; Rabbitfish Siganus canaliculatus; miR-17; Δ4 Fad; Δ6/Δ5 Fad