Leucine Promotes Milk Synthesis in Bovine Mammary Epithelial Cells via the PI3K-DDX59 Signaling
Leucine Promotes Milk Synthesis in Bovine Mammary Epithelial Cells via the PI3K-DDX59 Signaling
复制标题
亮氨酸通过 PI3K-DDX59 信号促进牛乳腺上皮细胞的乳汁合成
DOI：
10.1021/acs.jafc.9b03574
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发表时间：
2019
影响因子：
6.1
通讯作者：
Zhang Minghui
中科院分区：
文献类型：
--
作者：
Qiu Youwen;Qu Bo;Zhen Zhen;Yuan Xiaohan;Zhang Li;Zhang Minghui
亮氨酸是奶牛乳腺分泌乳汁的必需氨基酸，但其调控作用及其分子机制尚不清楚。本研究以牛乳腺上皮细胞（BMEC）为研究对象，探讨了亮氨酸对牛乳合成的影响及其机制。将亮氨酸（0、0.25、0.5、0.75、1.0和1.25 mM）添加到在无FBS的OPTI-MEM培养基中培养的BMEC中。亮氨酸显著促进乳蛋白和乳脂肪的合成，并且还增加mTOR信号蛋白的磷酸化和SREBP-1c的蛋白表达水平，其中在0.75 mM浓度下效果最显著。亮氨酸增加DDX 59的表达和核定位，基因功能丧失和获得实验进一步揭示了DDX 59介导亮氨酸对mTOR和SREBP-1c基因mRNA表达变化的刺激。PI 3 K抑制实验进一步检测到亮氨酸通过PI 3 K激活上调DDX 59的表达及其下游信号传导。ChIP-qPCR分析进一步证明DDX 59与mTOR和SREBP-1c的启动子区域结合。综上所述，这些数据证明DDX 59正调控导致乳汁合成的mTOR和SREBP-1c信号通路，亮氨酸通过PI 3 K-DDX 59信号通路调节这两条信号通路。
Leucine is an essential amino acid in the milk production of bovine mammary glands, but the regulatory roles and molecular mechanisms of leucine are still not known well. This study investigated the roles of leucine on milk synthesis and explored the corresponding mechanism in bovine mammary epithelial cells (BMECs). Leucine (0, 0.25, 0.5, 0.75, 1.0, and 1.25 mM) was added to BMECs that were cultured in FBS-free OPTI-MEM medium. Leucine significantly promoted milk protein and milk fat synthesis and also increased phosphorylation of mTOR signaling protein and the protein expression levels of SREBP-1c, with the most significant effects at 0.75 mM concentration. Leucine increased the expression and nuclear localization of DDX59, and loss and gain of gene function experiments further reveal that DDX59 mediates the stimulation of leucine on the mRNA expression variation ofmTORandSREBP-1cgenes. PI3K inhibition experiment further detected that leucine upregulated expression of DDX59 and its downstream signaling via PI3K activation. ChIP-qPCR analysis further proved the binding of DDX59 to the promoter regions ofmTORandSREBP-1c. In summary, these data prove that DDX59 positively regulates the mTOR and SREBP-1c signaling pathways leading to synthesis of milk, and leucine regulates these two signaling pathways through the PI3K-DDX59 signaling.