Impact of let-7g on Proliferation and Lactation of Mouse Mammary Epithelial Cells

Let-7g, a member of the let-7 family, regulates gene expression at the post-transcriptional level. The study explored a series of biological effects of mouse mammary epithelial cells that let-7g was produced. The differential expression of let-7g was detected by qRT-PCR in different developmental stages of the mouse mammary gland. let-7g expression and impact of let-7g on mouse mammary epithelial cells were analyzed by CASY-technology, qRT-PCR, Western blotting and HPLC inhibited let-7g expression of mouse mammary epithelial cells through gene silencing. The results showed that qRT-PCR identified let-7g as being down-regulated in mouse mammary epithelial cells after it was inhibited. Mouse mammary epithelial cells with low expression of let-7g displayed higher expression of TGFβR I protein than those with high expression of let-7g, suggesting that low let-7g expression contributed to TGFβR I over-expression. Finally, the expression of let-7g was down-regulated, which significantly enhanced the proliferation of mouse mammary epithelial cells, and increased expression of β-Casein. The data indicated that let-7g could negatively regulate the expression of target Tgfbr1 by complementary combination in mouse mammary epithelial cells, and then regulate the cell proliferation and expression of β-Casein by suppressing the TGFβR I expression.