低浓度胆酸上调JNK蛋白表达:可促进肝细胞DNA的合成?

Low concentration of cholic acid up-regulates JNK protein expression: Can it promote synthesis of liver cell DNA?

背景:胆汁酸在生理情况下对脂类物质的消化吸收和胆固醇代谢发挥着重要作用,超负荷的胆汁酸能够导致肝细胞的凋亡与坏死,而有关低浓度的胆汁酸对肝细胞增殖有何影响研究较少。目的:探索低浓度胆酸对大鼠肝细胞增殖和JNK,p38-MAPK蛋白表达的影响。方法:原代培养Wistar大鼠肝细胞48h,更换含有0,10,20,40和80μmol/L胆酸的培养液继续培养12h,MTT法检测肝细胞存活率;流式细胞仪检测细胞周期,计算肝细胞S期的相对百分比;免疫印迹技术检测JNK和p38-MAPK的蛋白表达。结果与结论:浓度为40μmol/L以下的胆酸对肝细胞的存活率和肝细胞p38-MAPK蛋白表达无显著影响,但使肝细胞S期细胞比例和肝细胞JNK蛋白表达量显著升高(P<0.05,P<0.01);80μmol/L的胆酸使肝细胞存活率、肝细胞S期细胞比例、JNK表达量则显著下降(P<0.01),而使p38-MAPK蛋白表达显著上升(P<0.01)。因此,认为低浓度的胆酸可促进肝细胞DNA的合成,可能与上调JNK蛋白表达有关。

BACKGROUND： Under physiological conditions, bile acids play an important role in the digestion and absorption of lipids and cholesterol metabolism, and the bile acid overload can lead to liver cell apoptosis and necrosis. However, studies of the effect of the low-concentration bile acids on liver cell proliferation are still few. OBJECTIVE： To investigate the effect of the low-concentration cholic acid （CA） on rat liver cell proliferation and JNK, p38-MAPK protein expression. METHODS： Rat hepatocytes were cultured in primary culture for 48 hours, then they were incubated in medium containing 0, 10, 20, 40, 80 μmol/L CA for 12 hours. The cell survival rate was determined by MTT assay. The cell cycles were detected by flow cytometry, and the relative percentage of S phase was calculated. The expression of JNK and p38-MAPK protein was detected by western blotting. RESULTS AND CONCLUSION： There was no significant difference in survival rate below the concentration of 40 μmol/L CA; however, the relative percentage of S phase and JNK protein expression were significantly increased by 40 μmol/L CA （P 0.05, P 0.01）. 80 μmol/L CA significantly decreased survival rate, relative percentage of S phase, and JNK expression （P 0.01） but significantly increased p38-MAPK protein expression （P 0.01）. Therefore, low-concentrations CA could promote liver cell DNA synthesis, which might be caused by an increase of the JNK protein expression.