赖氨酸对奶牛乳腺上皮细胞内乳糖合成相关基因表达的影响

Effects of Lysine on Expression of Genes Related to Lactose Synthesis in Bovine Mammary Epithelial Cells

本试验旨在研究赖氨酸(Lys)对奶牛乳腺上皮细胞(BMECs)内乳糖合成相关基因表达的影响,深入探讨Lys对乳糖合成的影响机理。将第3代BMECs随机分为6个组,每组6个重复,各组细胞培养液中Lys的终浓度分别为0.5(对照)、1.0、2.0、4.0、8.0和16.0 mmol/L,细胞在37℃、5%CO2条件下培养48 h。结果表明:适宜浓度Lys对乳糖含量和葡萄糖转运载体蛋白1(GLUT1)、已糖激酶Ⅰ(HKⅠ)和已糖激酶Ⅱ(HKⅡ)基因表达量的影响呈显著的剂量依赖关系(P<0.05);方差分析结果显示,添加Lys显著或趋于显著影响乳糖含量及乳糖合成相关基因表达。与对照组相比,2.0~16.0 mmol/L组乳糖含量较高(0.05<P<0.10),4.0~16.0 mmol/L组G LUT1基因表达量显著升高(P<0.05),2.0~8.0 mmol/L组α-乳清白蛋白(LALBA)和β-1,4-半乳糖基转移酶-1(β-4GALT1)基因表达量显著升高(P<0.05),8.0~16.0 mmol/L组HKⅡ基因表达量显著升高(P<0.05);但1.0~2.0 mmol/L组HKⅡ基因表达量显著下降(P<0.05),4.0~16.0 mmol/L组HKⅠ基因表达量下降,尤以16.0 mmol/L组显著低于对照组(P<0.05)。综上所述,Lys对乳糖含量和GLUT1、HKⅠ和HKⅡ基因表达量的影响存在显著的剂量依赖,Lys浓度为2.0~8.0 mmol/L时,对BMECs内乳糖合成促进效果较好。

The objective of this study was to determine the effect of lysine （Lys） on the expression of genes related to lactose synthesis in bovine mammary epithelial cells （BMECs）, and to discuss the mechanism of the effect of Lys on lactose synthesis. The third generation BMECs were divided into 6 groups with 6 repetitions, and were cultured in the medium at concentrations of 0.5 （control）, 1.0, 2.0, 4.0, 8.0 and 16.0 mmol/L Lys, respectively, for 48 h cultivation at 37 ℃ and 5% CO 2. The results showed as follows： the proper concentration of Lys had a significant dose-dependent effect on the content of lactose and the expression levels of glucose transporter 1 （ GLUT1 ）, hexokinase Ⅰ （ HKⅠ ） and hexokinase Ⅱ （ HKⅡ ） genes （ P 〈0.05）; the variance analysis results showed that increasing Lys concentration had a significant or tend to significant effect on the content of lactose and the expression of genes related to lactose synthesis. Compared with the control, the content of lactose in 2.0 to 16.0 mmol/L Lys groups was higher （0.05〈 P 〈0.10）, the expression level of GLUT1 gene in 4.0 to 16.0 mmol/L Lys groups increased significantly （ P 〈0.05）, the expression levels of α-lactalbumin （ LALBA ） and β-1,4-galactosyltransferase 1 （ β-4GALT1 ） genes in 2.0 to 8.0 mmol/L Lys groups increased significantly （ P 〈0.05）, and the expression level of HKⅡ gene in 8.0 to 16.0 mmol/L Lys groups increased significantly （ P 〈0.05）; the expression level of HK Ⅱ gene in 1.0 to 2.0 mmol/L Lys groups was inhibited significantly （ P 〈0.05）; the expression of HKⅠ gene in 4.0 to 16.0 mmol/L Lys groups was inhibited, especially for that in 16.0 mmol/L Lys group, which was significantly lower than that in the control （ P 〈0.05）. In conclusion, it shows that the Lys significantly improves the content of lactose, GLUT1 , HKⅠ and HKⅡ genes expression in dose-dependent manner and the optimal Lys concentrations for lactose synthesis is 2.0 to 8.0 mmol/L.