FADS1 overexpression promotes fatty acid synthesis and triacylglycerol accumulation inhibiting the AMPK/SREBP1 pathway in goat mammary epithelial cells.

Delta-5 desaturase (D5D), encoded by the fatty acid desaturase 1 (FADS1) gene, is a rate-limiting enzyme in polyunsaturated fatty acid (PUFA) synthesis that influences the PUFA levels in milk fat. However, the function and molecular mechanism of FADS1 in milk fat metabolism remain largely unknown. The overexpression increased the triglyceride content, lipid droplet size, and expression of genes related to fatty acid synthesis ( and ), intracellular fatty acid transporters ( and ) and triacylglycerol synthesis gene (). It also significantly promoted the SREBP1 nuclear translocation by inhibiting the AMPK activation. In addition, FADS1 overexpression inhibited cell proliferation and arrested cell cycle at the G1 phase. These findings reveal a novel FADS1-AMPK-SREBP1 pathway regulating milk fat production in the goat mammary gland.