BioProject

The transition from pregnancy to lactation is a critical event in the survival of the newborn since all the nutrient requirements of the infant are provided by milk. More...

The transition from pregnancy to lactation is a critical event in the survival of the newborn since all the nutrient requirements of the infant are provided by milk. While milk contains numerous components, including proteins, that aid in maintaining the health of the infant, lactose and milk fat represent the critical energy providing elements of milk. Much of the research to date on mammary epithelial differentiation has focused upon expression of milk protein genes, providing a somewhat distorted view of alveolar differentiation and secretory activation. While expression of milk protein genes increases during pregnancy and at secretory activation, the genes whose expression is more tightly regulated at this transition are those that regulate lipid biosynthesis. The sterol regulatory element binding protein (SREBP) family of transcription factors is recognized as regulating fatty acid and cholesterol biosynthesis. We propose that SREBP1 is a critical regulator of secretory activation with regard to lipid biosynthesis, in a manner that responds to diet, and that the serine/threonine protein kinase Akt influences this process, resulting in a highly efficient lipid synthetic organ that is able to support the nutritional needs of the newborn. Keywords: developmental time course (time series) throughout pregnancy, lactation and involution. Overall design: Key points are examined in a time series of FVB mouse mammary gland development, secretory activation, lactation and involution. Quadruplicate mice (four biological replicates) at each time point were used for statistical power totalling 40 individual arrays in this study. Mice were as staged pregnant day 1 the day that post coital plug was observed, and similarly, lactation day 1 was the first day after birth. Involution day 2 is a forced weening model, where day 9 lactating dams had their litters removed for two days and then the dams were killed. Less...