NF-κB/SOCS信号通路在LPS所致奶牛乳脂肪含量降低中的作用研究

Milk fat is the main substance to determine the nutritional quality of cow's milk. Milk fat content and fatty acid profile play a vital role in human health and food safety. LPS could induce milk fat depression and lead to a major economic impact in the dairy industry. However, the underlying mechanism of LPS-induced milk fat depression remains unclear. It is reported that LPS can activate NF-κB/SOCS signaling pathway in many different types of cells, and the activation of NF-κB/SOCS signaling pathway has a potential role in regulating lipid metabolism. This suggests a potential role for the NF-κB/SOCS signaling pathway in LPS-induced milk fat depression in dairy cows. The project will use western blotting, real-time RT-PCR, ELISA, EMSA and other methods to characterize the sequential change of the activation of NF-κB/SOCS signaling pathway, the transcriptional activity of PPARγ, SREBP-1, and LXR, the expression of lipid metabolism genes, and the lipid droplet formation in dairy cow mammary epithelial cells after LPS challenge so as to identify the role of NF-κB/SOCS signaling pathway in LPS-induced milk fat depression in dairy cows. These results will provide scientific basis to further study the regulatory mechanism of milk fat synthesis and improve the nutritional quality of cow's milk.

乳脂肪是构成牛奶营养品质的重要物质基础，其含量和组成与人类健康密切相关。LPS可降低奶牛乳脂肪含量，但LPS影响乳腺中脂代谢功能的机制尚不明确。已有研究表明，LPS可活化多种细胞内NF-κB/SOCS信号通路，而NF-κB/SOCS信号通路具有调控脂代谢活动的潜在功能，提示该信号通路可能在LPS所致奶牛乳脂肪含量降低中具有重要作用。因此，本项目拟研究LPS处理奶牛乳腺上皮细胞后NF-κB/SOCS信号通路活性的时序性变化，脂代谢转录因子转录活性、脂代谢酶基因表达水平和脂滴形成情况的时序性变化；并用相关信号通路抑制剂预处理乳腺上皮细胞，明确NF-κB/SOCS信号通路对脂代谢转录因子转录活性的影响，以期揭示NF-κB/SOCS信号通路在LPS所致奶牛乳脂肪含量降低中的作用，为深入认识乳脂肪代谢调控机制提供科学依据，为通过人工干预手段来提高牛奶营养品质奠定研究基础。

乳脂肪是构成牛奶营养品质的重要物质基础，其含量和组成与人类健康密切相关。LPS可降低奶牛乳脂肪含量，但LPS影响乳腺中脂代谢功能的机制尚不明确。在自然科学基金青年基金项目《NF-κB/SOCS信号通路在LPS所致奶牛乳脂肪含量降低中的作用研究》资助下，按照计划任务书要求，课题组建立了具有乳脂肪合成功能的奶牛乳腺上皮细胞分离培养平台，利用上述细胞平台构建了奶牛乳腺感染体外细胞模型，明确了脂多糖（LPS）刺激细胞的最佳工作浓度和刺激时间，检测了LPS刺激乳腺上皮细胞后炎症细胞因子基因转录水平、核转录因子（NF-κB）及细胞因子信号转导抑制因子（SOCS）1/3表达水平、脂代谢转录因子PPARγ、SREBP-1 和LXR 蛋白水平、转录调控活性和核转位情况、脂代谢相关酶基因转录水平、细胞内脂滴含量和培养液中甘油三酯（TG）含量，证实了LPS刺激乳腺上皮细胞后可活化NF-κB/ SOCS信号通路，并对脂代谢转录因子转录活性和乳脂合成功能产生重要影响。该研究为深入认识乳脂肪代谢调控机制提供了研究依据，为通过人工干预手段来提高牛奶营养品质奠定了研究基础。