Protein 14-3-3 epsilon Regulates Cell Proliferation and Casein Synthesis via PI3K-mTOR Pathway in Dairy Cow Mammary Epithelial Cells

摘要

Cell proliferation and casein synthesis of dairy cow mammary epithelial cells (DCMECs) are regulated by many factors. This research aimed to investigate the effect of 14-3-3 epsilon on cell proliferation and casein synthesis in DCMECs and to reveal the underlying mechanism. Overexpressing or inhibiting 14-3-3 epsilon demonstrated that cell proliferation; casein synthesis; expression of mTOR, p-mTOR, S6K1, and p-S6K1; and lysosomal localization of mTOR were all up-regulated by 14-3-3 epsilon overexpressing and down-regulated by 14-3-3 epsilon inhibiting. In addition, inhibiting mTOR demonstrated that the up-regulation of cell proliferation and casein synthesis in response to 14-3-3 epsilon overexpressing was removed by inhibiting mTOR Furthermore, the regulatory mechanism of 14-3-3 epsilon was analyzed by coimmunoprecipitation, and we found that 14-3-3 epsilon could interact with PI3K and activate mTORC1 pathway via PI3K. In addition, DCMECs were treated with insulin and prolactin, and the result showed that the cell proliferation and the expression of CSN2 and 14-3-3 epsilon were all up-regulated by these hormones. In conclusion, the current research showed that 14-3-3 epsilon is an important positive regulatory factor for cell proliferation and casein synthesis in DCMECs, as it up-regulates cell proliferation and casein synthesis via activating PI3K-mTOR pathway.