College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, No. 2 Xinyang Road, Sartu District, Daqing163319, P.R. China.
Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, No. 2 Xinyang Road, Sartu District, Daqing163319, P.R. China.
J Dairy Res. 2020 Nov;87(4):456-462. doi: 10.1017/S0022029920000990. Epub 2020 Dec 2.
Lipopolysaccharides (LPS) could induce milk fat depression via regulating the body and blood fat metabolism. However, it is not completely clear how LPS might regulate triglyceride synthesis in dairy cow mammary epithelial cells (DCMECs). DCMECs were isolated and purified from dairy cow mammary tissue and treated with LPS. The level of triglyceride synthesis, the expression and activity of the liver X receptor α (LXRα), enzymes related to de novo fatty acid synthesis, and the expression of the fatty acid transporters were investigated. We found that LPS decreased the level of triglyceride synthesis via a down-regulation of the transcription, translation, and nuclear translocation level of the LXRα. The results also indicated that the transcription level of the LXRα target genes, sterol regulatory element binding protein 1 (SREBP1), fatty acid synthetase (FAS), acetyl-CoA carboxylase-1 (ACC1), were significantly down-regulated in DCMECs after LPS treatment. Our data may provide new insight into the mechanisms of milk fat depression caused by LPS.
脂多糖（LPS）可通过调节机体和血液脂肪代谢诱导乳脂下降。然而，LPS 如何调节奶牛乳腺上皮细胞（DCMEC）中甘油三酯的合成尚不完全清楚。本研究从奶牛乳腺组织中分离和纯化 DCMEC 并进行 LPS 处理，研究甘油三酯合成水平、肝 X 受体α（LXRα）的表达和活性、从头合成脂肪酸相关酶以及脂肪酸转运蛋白的表达。结果发现 LPS 通过下调 LXRα 的转录、翻译和核易位水平来降低甘油三酯的合成水平。结果还表明，LPS 处理后 DCMEC 中 LXRα 靶基因固醇调节元件结合蛋白 1（SREBP1）、脂肪酸合成酶（FAS）、乙酰辅酶 A 羧化酶-1（ACC1）的转录水平显著下调。本研究结果可能为 LPS 引起乳脂下降的机制提供新的见解。
