Regulation of Δ6Fads2 Gene Involved in LC-PUFA Biosynthesis Subjected to Fatty Acid in Large Yellow Croaker (Larimichthys crocea) and Rainbow Trout (Oncorhynchus mykiss)

Delta 6 fatty acyl desaturase (Delta 6Fads2) is regarded as the first rate-limiting desaturase that catalyzes the biosynthesis of long-chain polyunsaturated fatty acids (LC-PUFA) from 18-carbon fatty acid in vertebrates, but the underlying regulatory mechanism of fads2 has not been comprehensively understood. This study aimed to investigate the regulation role of fads2 subjected to fatty acid in large yellow croaker and rainbow trout. In vivo, large yellow croaker and rainbow trout were fed a fish oil (FO) diet, a soybean oil (SO) diet or a linseed oil (LO) diet for 10 weeks. The results show that LO and SO can significantly increase fads2 expression (p < 0.05). In vitro experiments were conducted in HEK293T cells or primary hepatocytes to determine the transcriptional regulation of fads2. The results show that CCAAT/enhancer-binding protein alpha (C/EBP alpha) can up-regulate fads2 expression. GATA binding protein 3 (GATA3) can up-regulate fads2 expression in rainbow trout but showed opposite effect in large yellow croaker. Furthermore, C/EBP alpha protein levels were significantly increased by LO and SO (p < 0.05), gata3 expression was increased in rainbow trout by LO but decreased in large yellow croaker by LO and SO. In conclusion, we revealed that FO replaced by LO and SO increased fads2 expression through a C/EBP alpha and GATA3 dependent mechanism in large yellow croaker and rainbow trout. This study might provide critical insights into the regulatory mechanisms of fads2 expression and LC-PUFA biosynthesis.

Automated summary

This study investigated the regulatory role of fads2 in response to fatty acids in large yellow croaker and rainbow trout. The results showed that linseed oil (LO) and soybean oil (SO) significantly increased fads2 expression. In vitro experiments revealed that CCAAT/enhancer-binding protein alpha (C/EBP alpha) and GATA binding protein 3 (GATA3) played important roles in the transcriptional regulation of fads2. Furthermore, the replacement of fish oil (FO) by LO and SO increased fads2 expression through a C/EBP alpha and GATA3 dependent mechanism in both species. This study provides insights into the regulatory mechanisms of fads2 expression and LC-PUFA biosynthesis.