Hepatocyte nuclear factor 4α (Hnf4α) is involved in transcriptional regulation of Δ6/Δ5 fatty acyl desaturase (fad) gene expression in marine teleost Siganus canaliculatus

Publication date: Available online 13 September 2019Source: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular BiologyAuthor(s): Yewei Dong, Shuqi Wang, Cuihong You, Dizhi Xie, Qingyan Jiang, Yuanyou LiAbstractAs the first marine teleost demonstrated to biosynthesize long-chain polyunsaturated fatty acids (LC-PUFAs) from C18 precursors such as linoleic acid (LOA, 18:2n-6) and α-linolenic acid (ALA, 18:3n-3), the rabbitfish (Siganus canaliculatus) contains the complete enzymatic system for LC-PUFA biosynthesis, including Δ6/Δ5 fatty acid desaturase (Fad), Δ4 Fad, and elongase 5 (Elovl5). Previously, our group demonstrated that hepatocyte nuclear factor 4α (Hnf4α) is a transcription factor (TF) for rabbitfish Δ4 fad and elovl5, and interacts with the core promoter of Δ6/Δ5 fad. To fully clarify the role of Hnf4α in the regulation of LC-PUFA biosynthesis, the present study aimed to explore the regulatory role of Hnf4α on Δ6/Δ5 fad gene expression. First, Hnf4α overexpression and agonist assays identified the Hnf4α response region in the Δ6/Δ5 fad core promoter as −456 bp to +51 bp. Bioinformatic analysis predicted four potential Hnf4α binding elements in the core promoter, which were confirmed by site-directed mutation and functional assays in a dual luciferase assay system. Moreover, the mRNA expression levels of hnf4α, Δ6/Δ5 fad, and Δ4 fad were significantly increased in the S. canaliculatus hepatocyte line (SCHL) cells afte...
Source: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology - Category: Molecular Biology Source Type: research