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

Abstract

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 Elovl5 elongase in Trachinotus ovatus. The functional study showed that ToElovl5 displayed high elongation activity toward C18 and C20 PUFA. To investigate whether PPARαb was a regulator of Elovl5, we also reported the sequence of T. ovatus PPARαb (ToPPARαb). 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 Elovl5. Moreover, PPARαb overexpression led to a clear time-dependent enhancement of ToElovl5 promoter expression in HEK 293T cells. Fourth, the agonist of PPARαb prominently increased PPARαb and Elovl5 expression, while PPARαb depletion by RNAi or an inhibitor was correlated with a significant reduction of Elovl5 transcription in T. ovatus caudal fin cells (TOCF). In conclusion, the present study provides the first evidence of the positive regulation of Elovl5 transcription by PPARαb and contributes to a better understanding of the transcriptional mechanism of PPARαb in fish.

Identification of Fatty Acid Desaturase 6 in Golden Pompano Trachinotus Ovatus (Linnaeus 1758) and Its Regulation by the PPARαb Transcription Factor

“…Protein and mRNA levels of ToPPARαb were significantly decreased in a time-dependent manner by RNAi knockdown of PPARαb , suggesting effective knockdown of ToPPARαb expression in T. ovatus caudal fin (TOCF) cells (Figure 7A,C) [27]. When ToPPARαb expression was reduced, protein and mRNA levels of ToFads6 were dramatically depleted, when compared with the control group at the corresponding time points (Figure 7B,D).…”

“…Specific primers for real-time quantitative PCR (qRT-PCR) were designed by Primer Premier 5.0 (Premier Biosoft, Palo Alto, CA, USA) based on cloned nucleotide sequences (Table S1). The translation elongation factor 1-alpha ( EF1α ) and PPARαb were verified by sequencing and were used as a reference and target gene, respectively [27,47]. The qRT-PCR amplifications were performed in a quantitative thermal cycler (Mastercycler EP Realplex, Eppendorf, Hamburg, Germany).…”

Seawater Culture Increases Omega-3 Long-Chain Polyunsaturated Fatty Acids (N-3 LC-PUFA) Levels in Japanese Sea Bass (Lateolabrax japonicus), Probably by Upregulating Elovl5

“…Some studies have focused on the regulatory mechanisms of FADS2 and Elovl5 genes. For instance, some transcription factors, Sterol Regulatory Element Binding Protein-1 (SREBP-1) and Peroxisome Proliferator-Activated Receptors (PPARs), regulate the two genes [24,25]. In addition to nutritional factors, environmental factors have been demonstrated to mediate FADS2 gene expression regulation in fish.…”

Sterol regulatory element binding protein and Sp1 is required for transcriptional activation of a freshwater carnivorous fish (Channa striata) elovl5 elongase

“…The participation of Fads and Elovl in LC-PUFA biosynthesis partly depends on the binding of specific transcription factors on their respective response elements in the promoter regions, and these activities are tightly regulated by hormones and nutritional status. To date, literature on teleost elovl5 promoters are limited to marine and diadromous species (Li et al, 2016, Carmona-Antonanzas et al, 2016, Zhu et al, 2018. The snakehead, a freshwater carnivorous fish, is an important candidate for intensive aquaculture in tropical countries while the zebrafish, a useful model for studying the function and regulation of Elovl and Fads (Hastings et al, 2001, Agaba et al, 2004, Tan et al, 2010, Monroig et al, 2010, Tay et al, 2018.…”

“…Accordingly, efforts to characterise the upstream promoters in these genes began to transpire. So far, the promoter of elovl5 have been isolated and characterised from salmon (Carmona-Antonanzas et al, 2016), orange grouper (Li et al, 2016), rabbit fish and golden pompano (Zhu et al, 2018). In contrast, there is no investigation on any freshwater species.…”