Enhancement of milk protein expression in mammary epithelial cells via co-culturing with preadipocyte cells

Abstract

Mammary gland development is critically dependent on the interactions between its stromal and epithelial compartments. In this study, we established a co-culture of bovine mammary epithelial Mac-T cells and murine preadipocyte 3T3-L1 cells. Mac-T cells were co-cultured with 3T3-L1 cells for four days and production of milk proteins was induced for three days. After seven days of co-culturing, the number of alveolar-like colonies in the presence of 3T3-L1 cells was significantly higher than that in control group. Expression levels of αS1-casein and β-casein mRNAs were significantlyincreased by co-culturing with 3T3-L1 cells. In addition, casein protein production was significantly higher in the co-culture of Mac-T cells with 3T3-L1 cells than in control Mac-T cells. Substances that induced casein production in Mac-T cells also stimulated adipogenesis in 3T3-L1 cells. We suggest that a co-culture system of bovine mammary epithelial cells and preadipocyte cells is an efficient method for in vitro milk protein production.