Goat FADS2 controlling fatty acid metabolism is directly regulated by SREBP1 in mammary epithelial cells.

The fatty acid desaturase 2 (FADS2) is the first rate-limiting enzyme in polyunsaturated fatty acids (PUFAs) biosynthesis in mammals. This study aimed to investigate the function and transcriptional regulation mechanism of FADS2 in goat mammary epithelial cells (GMECs). The content of triacylglycerol (TAG) was enhanced with lipid droplet accumulation in FADS2-overexpressed GMECs. Overexpression of FADS2 was positively correlated with elevated concentrations of docosahexaenoic acid (DHA) in GMECs. Furthermore, site-directed mutation and chromatin immunoprecipitation (ChIP) assays simultaneously demonstrated that FADS2 was directly regulated by SREBP1 transcriptional factor binding to sterol regulatory element (SRE) in vitro and in vivo. In addition, genetic ablation of SRE1 and SRE2 in the genome resulted in a significant reduction in the mRNA levels of FADS2 via the CRISPR interference (CRISPRi) system. Altogether, this study discovered that the SREBP1 exerts control on FADS2 to regulate milk fatty acids, and provides a theoretical approach for improving milk quality via genetic approaches.