title: Mammary alveolar cell asin vitroevaluation system for casein gene expression involved in glucose level.
abstract: OBJECTIVE
  Glucose is an essential fuel in the energy metabolism and synthesis pathways of all mammalian cells. In lactating animals, glucose is the major precursor for lactose and is a substrate for the synthesis of milk proteins and fat in mammary secretory (alveolar) epithelial cells. However, clear utilization of glucose in mammary cells during lactogenesis is still unknown, due to the lack ofin vitroanalyzing models. Therefore, the objective of this study was to test the reliability of the mammary alveolar (MAC-T) cell as anin vitrostudy model for glucose metabolism and lactating system.
  
  
  METHODS
  Undifferentiated MAC-T cells were cultured in three types of Dulbecco's modified Eagle's medium with varying levels of glucose (no-glucose: 0 g/L, low-glucose: 1 g/L, and high-glucose: 4.5 g/L) for 8 d, after which differentiation to casein secretion was induced. Cell proliferation and expression levels of apoptotic genes, Insulin like growth factor-1 (IGF1) receptor, oxytocin receptor, αS1, αS2, and β casein genes were analyzed at 1, 2, 4, and 8 d after differentiation.
  
  
  RESULTS
  The proliferation of MAC-T cells with high-glucose treatment was seen to be significantly higher. Expression of apoptotic genes was not affected in any group. However, expression levels of the mammary development related gene (IGF1 receptor) and lactation related gene (oxytocin receptor) were significantly higher in the low-glucose group. Expressions of αS1-casein, αS2-casein, and β-casein were also higher in the low-glucose treated group as compared to that in the no-glucose and high-glucose groups.
  
  
  CONCLUSIONS
  The results demonstrated that although a high-glucose environment increases cell proliferation in MAC-T cells, a low-glucose treatment to MAC-T cells induces higher expression of casein genes. Our results suggest that the MAC-T cells may be used as anin vitromodel to analyze mammary cell development and lactation connected with precise biological effects.
authors.affiliation: Department of Stem Cell and Regenerative Biology, College of Animal Bioscience and Technology, Konkuk University, Seoul 143-701, Korea.
authors.forename: Young Tae
authors.initials: YT
authors.lastname: Heo
authors.affiliation: Department of Stem Cell and Regenerative Biology, College of Animal Bioscience and Technology, Konkuk University, Seoul 143-701, Korea.
authors.forename: Woo Tae
authors.initials: WT
authors.lastname: Ha
authors.affiliation: Department of Stem Cell and Regenerative Biology, College of Animal Bioscience and Technology, Konkuk University, Seoul 143-701, Korea.
authors.forename: Ran
authors.initials: R
authors.lastname: Lee
authors.affiliation: Division of Food Bioscience, RIBHS, College of Biomedical and Health Sciences, Konkuk University, Chung-ju 380-701, Korea.
authors.forename: Won-Young
authors.initials: WY
authors.lastname: Lee
authors.affiliation: Department of Animal Resources Development Dairy Science Division, National Institute of Animal Science, RDA, Cheonan 331-801, Korea.
authors.forename: Ha Yeon
authors.initials: HY
authors.lastname: Jeong
authors.affiliation: Sooam Biotech Research Foundations, Seoul 152-895, Korea.
authors.forename: Kyu Chan
authors.initials: KC
authors.lastname: Hwang
authors.affiliation: Department of Stem Cell and Regenerative Biology, College of Animal Bioscience and Technology, Konkuk University, Seoul 143-701, Korea.
authors.forename: Hyuk
authors.initials: H
authors.lastname: Song
keywords: Casein; Glucose; Insulin-like Growth Factor-1 (IGF-1); Mammary alveolar (MAC-T) Cell; Oxytocin