Fan Xinyang, Qiu Lihua, Zhu Wei, Huang Lige, Tu Xingtiao, Miao Yongwang
Faculty of Animal Science and Technology, Yunnan Agricultural University, Kunming 650201, China.
Foods. 2023 Feb 6;12(4):708. doi: 10.3390/foods12040708.
Milk protein content is a key quality indicator of milk, and therefore elucidating its synthesis mechanism has been the focus of research in recent years. Suppressor of cytokine signaling 1 () is an important inhibitor of cytokine signaling pathways that can inhibit milk protein synthesis in mice. However, it remains elusive whether plays roles in the milk protein synthesis in the buffalo mammary gland. In this study, we found that the mRNA and protein expression levels of in buffalo mammary tissue during the dry-off period was significantly lower than those during lactation. Overexpression and knockdown experiments of showed that it influenced the expression and phosphorylation of multiple key factors in the mTOR and JAK2-STAT5 signaling pathways in buffalo mammary epithelial cells (BuMECs). Consistently, intracellular milk protein content was significantly decreased in cells with overexpression, while it increased significantly in the cells with knockdown. The CCAAT/enhancer binding protein α (CEBPA) could enhance the mRNA and protein expression of and its promoter activity in BuMECs, but this effect was eliminated when CEBPA and NF-κB binding sites were deleted. Therefore, CEBPA was determined to promote transcription via the CEBPA and NF-κB binding sites located in the promoter. Our data indicate that buffalo plays a significant role in affecting milk protein synthesis through the mTOR and JAK2-STAT5 signaling pathways, and its expression is directly regulated by CEBPA. These results improve our understanding of the regulation mechanism of buffalo milk protein synthesis.
乳蛋白含量是牛奶的关键质量指标，因此阐明其合成机制一直是近年来的研究重点。细胞因子信号转导抑制因子1（）是细胞因子信号通路的重要抑制剂，可抑制小鼠乳蛋白合成。然而，其在水牛乳腺乳蛋白合成中是否发挥作用仍不清楚。在本研究中，我们发现干奶期水牛乳腺组织中的mRNA和蛋白表达水平显著低于泌乳期。的过表达和敲低实验表明，它影响水牛乳腺上皮细胞（BuMECs）中mTOR和JAK2-STAT5信号通路中多个关键因子的表达和磷酸化。一致地，过表达的细胞中细胞内乳蛋白含量显著降低，而敲低的细胞中则显著增加。CCAAT/增强子结合蛋白α（CEBPA）可增强BuMECs中 的mRNA和蛋白表达及其启动子活性，但当CEBPA和NF-κB结合位点缺失时，这种作用被消除。因此，确定CEBPA通过位于 启动子中的CEBPA和NF-κB结合位点促进 转录。我们的数据表明，水牛 通过mTOR和JAK2-STAT5信号通路在影响乳蛋白合成中发挥重要作用，其表达直接受CEBPA调控。这些结果增进了我们对水牛乳蛋白合成调控机制的理解。
