AUTHOR=Zhu Ke-Cheng , Song Ling , Zhao Chao-Ping , Guo Hua-Yang , Zhang Nan , Guo Liang , Liu Bao-Suo , Jiang Shi-Gui , Zhang Dian-Chang 

TITLE=The Transcriptional Factor PPARαb Positively Regulates Elovl5 Elongase in Golden Pompano Trachinotus ovatus (Linnaeus 1758)

JOURNAL=Frontiers in Physiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2018.01340

DOI=10.3389/fphys.2018.01340

ISSN=1664-042X

ABSTRACT=<p>The nuclear peroxisome proliferator-activated receptors (PPARs) regulate the transcription of elongases of very long-chain fatty acids (Elovl), which are involved in polyunsaturated fatty acid (PUFA) biosynthesis in mammals. In the present study, we first characterized the function of <italic>Elovl5</italic> elongase in <italic>Trachinotus ovatus</italic>. The functional study showed that <italic>ToElovl5</italic> displayed high elongation activity toward C18 and C20 PUFA. To investigate whether PPARαb was a regulator of <italic>Elovl5</italic>, we also reported the sequence of <italic>T. ovatus PPARαb</italic> (<italic>ToPPARαb</italic>). The open reading frame (ORF) sequence encoded 469 amino acids possessing four typical characteristic domains, including an N-terminal hypervariable region, a DNA-binding domain (DBD), a flexible hinge domain and a ligand-binding domain (LBD). Thirdly, promoter activity experiments showed that the region from PGL3-basic-Elovl5-5 (-146 bp to +459 bp) was defined as the core promoter by progressive deletion mutation of <italic>Elovl5</italic>. Moreover, PPARαb overexpression led to a clear time-dependent enhancement of <italic>ToElovl5</italic> promoter expression in HEK 293T cells. Fourth, the agonist of PPARαb prominently increased <italic>PPARαb</italic> and <italic>Elovl5</italic> expression, while PPARαb depletion by RNAi or an inhibitor was correlated with a significant reduction of <italic>Elovl5</italic> transcription in <italic>T. ovatus</italic> caudal fin cells (TOCF). In conclusion, the present study provides the first evidence of the positive regulation of <italic>Elovl5</italic> transcription by PPARαb and contributes to a better understanding of the transcriptional mechanism of PPARαb in fish.</p>