THE FUNCTIONAL ROLE OF SREBP1C AND S14 IN REGULATION OF MAMMARY LIPID SYNTHESIS BY RUMEN-DERIVED BIOACTIVE FATTY ACIDS

Milk is an important source of nutrients and fat is the most variable milk component. Nutrition has a major impact on milk fat yield in the dairy cow, the most striking example being milk fat depression (MFD), which is commonly observed in cows fed certain diets. Our previous work has established that unique fatty acids produced as intermediates in the rumen during biohydrogenation of dietary polyunsaturated fatty acids regulate milk fat synthesis. Our goal is to develop an understanding of the regulation of milk fat synthesis by these naturally occurring bioactive fatty acids. The work proposed uses an integrated approach to understand the molecular regulation of milk fat synthesis by investigating the functional mechanisms of previously identified regulatory pathways. Specifically, we will first characterize the regulation of a key enzyme of lipid synthesis, acetyl-CoA carboxylase (ACC), test the functional role of two previously identified transcription factors (SREBP1 and S14), and further investigate the role of endoplasmic reticulum stress. This investigation will identify the functionally important signals regulating fat synthesis in the mammary gland. The long-term goal of this project is to increase the efficiency of milk fat synthesis by improving the understanding of the biological mechanisms underlying synthesis of milk fat. The knowledge gained will allow development of management strategies to improve productivity and animal well-being, optimize producer return and sustainability, and enhance quality of dairy products for consumers.