Milk fat content is an important index of milk product quality and one of the main traits of dairy cattle breeding. Perilipin1 is a predominant binding protein that mainly surrounds lipid droplets. Perilipin1 is important in the regulation of lipid metabolism. SREBP1 is a transcription factor that controls the expression of a variety of lipogenic genes and is the main regulator of milk fat synthesis. Here, we investigated the effect and mechanism of Perilipin1 on milk fat synthesis in bovine mammary epithelial cells ( BMECs ).
We found that the number and volume of lipid droplets increased following periplipin1 overexpression, leading to increased triglyceride accumulation, increased relative expression of lipid synthesis-related genes, decreased expression of lipid lipolysis genes, and increased SREBP1 activity . On the contrary, periplipin1 silencing reduced the number of lipid droplets, inhibited the synthesis of triglycerides, decreased the relative expression of lipid synthesis-related genes, increased the expression of lipid lipolysis genes, and downregulated the activity of SREBPI.
Perilipin1 promotes the synthesis of milk fat via up-regulating the activity of SREBP1 in BMECs. These findings laid the foundation for Holstein dairy cows to increase their milk fat content in molecular breeding.