泛素-蛋白酶体系统参与急性炎症状态下大鼠肝P-糖蛋白表达下调

Involvement of ubiquitin-proteasome pathway in down-regulation of P-glycoprotein in rat liver during acute inflammation

目的研究急性炎症状态下大鼠肝P-糖蛋白翻译后修饰的机制。方法 20只大鼠随机分成2组,模型组10只,对照组10只。模型组予以腹腔单次注射5 mg·kg-1脂多糖,对照组予以腹腔单次注射等体积0.9%氯化钠。24 h后,取肝组织,制备匀浆,分别用Western blot、免疫沉淀法和荧光法检测模型组和对照组的肝P-糖蛋白表达水平、P-糖蛋白泛素化水平和26S蛋白体活性的变化。结果与对照组相比,模型组肝P-糖蛋白蛋白表达水平显著降低(P<0.01),肝P-糖蛋白泛素化水平显著升高(P<0.01),26S蛋白体的活性显著升高(P<0.01)。结论泛素-蛋白酶体途径参与急性炎症状态下大鼠肝P-糖蛋白的下调。

Objective To explore the expression of P- glycoprotein（ P- gp） in rat liver during acute inflammation（ AI） and the possible mechanism involved. Methods Twenty rats were randomly divided into two groups： model group（ n = 10） and control group（ n = 10）. The rats in model group were treated by a single 5 mg·kg^- 1intraperitoneal injection of lipopolysaccharide（ LPS）. Control rats received equivalent injection of sterile normal saline. The levels of P- gp,ubiquitinated P- gp and 26 S proteasome activity in both groups were analyzed by Western blot, immunoprecipitation and fluorescence detection, respectively.Results Compared to the control groups,ubiquitination levels of liver P- gp and 26 S proteasome activity in model groups were significantly increased（ P〈 0. 01）,accompanied by an decrease of liver P- gp protein expression level. Conclusion The participation of the ubiquitin-proteasome system in down- regulation of liver P- gp expression levels under AI conditions.