14-3-3γ affects mTOR pathway and regulates lactogenesis in dairy cow mammary epithelial cells

• Published in: In vitro cellular & developmental biology. Animal 2015-08, Vol.51 (7), p.697-704
• Main Authors: Khudhair, Nagam, Luo, Chaochao, Khalid, Ahmed, Zhang, Li, Zhang, Shuang, Ao, Jinxia, Li, Qingzhang, Gao, Xuejun
• Format: Article
• Language: English
• Subjects: 14-3-3 Proteins - genetics; 14-3-3 Proteins - metabolism; Animal Genetics and Genomics; Animals; beta-casein; Biomedical and Life Sciences; Caseins - metabolism; Cattle; CELL AND TISSUE MODELS; Cell Biology; Cell Culture; cell growth; Cell Survival; cell viability; Cells, Cultured; cytoplasm; dairy cows; Dairying; Developmental Biology; epithelial cells; Epithelial Cells - drug effects; Epithelial Cells - metabolism; eukaryotic cells; Female; fluorescent antibody technique; gene silencing; Lactation; Life Sciences; lysine; Lysine - metabolism; Lysine - pharmacology; mammary glands; Mammary Glands, Animal - cytology; Mammary Glands, Animal - metabolism; methionine; Methionine - metabolism; Methionine - pharmacology; milk synthesis; prolactin; Prolactin - metabolism; Prolactin - pharmacology; protein synthesis; secretion; Signal Transduction; Stem Cells; TOR Serine-Threonine Kinases - metabolism; triacylglycerols; Triglycerides - metabolism
• ISSN: 1071-2690; 1543-706X
• DOI: 10.1007/s11626-015-9879-x

14-3-3 proteins are an acidic protein family that is highly conserved and widely distributed in eukaryotic cells. Recent studies have found that 14-3-3 proteins play critical roles in cell signal transductions, cell growth and differentiation, and protein synthesis. 14-3-3γ is an important member of 14-3-3 protein family. In our previous study, we found that 14-3-3γ was upregulated by estrogen in dairy cow mammary epithelial cell (DCMEC), but the function and mechanism of 14-3-3γ is not known. In this experiment, we first cultured and purified the primary DCMEC and found 14-3-3γ located both in the cytoplasm and nucleus by using immunofluorescence assay. Methionine, lysine, estrogen, and prolactin could upregulate the expression of 14-3-3γ, stimulate the secretion of β-casein and triglyceride, and raise the cell viability of DCMEC. We constructed a stable 14-3-3γ overexpression cell line of DCMEC and found that the expressions of mTOR and p-mTOR, the secretion of triglyceride and β-casein (CSN2), and the cell viability of DCMEC were all upregulated. We also observed the effects of 14-3-3γ gene silencing and gained consistent results with 14-3-3γ overexpression. These findings reveal that 14-3-3γ affects the mTOR pathway and regulates lactogenesis in DCMECs.