PI3K/Akt信号通路参与LPS诱导大鼠肺微血管内皮细胞表达RACK1及rac1

The PI3K/Akt signaling pathway involved in the expression of RACK1 and rac1 in the rat pulmonary microvascular endothelial cells induced by lipopolysaccharide

目的探讨磷脂酰肌醇3-激酶(PI3K)/丝氨酸-苏氨酸蛋白激酶(Akt)信号通路对脂多糖(LPS)诱导大鼠肺微血管内皮细胞(PMVEC)表达活化的蛋白激酶C受体1(RACK1)和ras相关C3肉毒菌毒物底物1(rac1)的影响。方法体外培养大鼠PMVEC:①LPS量效组:0、1、5、10 mg/L LPS与大鼠PMVEC孵育12 h;②LPS时效组:10 mg/L LPS与PMVEC孵育0、3、6、8、12、24 h;③IGF-1时效组:100 ng/ml IGF-1与PMVEC孵育0、3、6、8、12、24 h;④LPS+LY294002组:100 ng/ml LY294002预孵育PMVEC 1 h后加入10 mg/L LPS继续孵育12 h,设空白组、LPS组和LY294002组为对照。所有干预结束后Western blot法检测RACK1、rac1及p-Akt蛋白表达。结果①LPS量效组:RACK1、rac1及p-Akt蛋白表达量均呈浓度依赖性增加,各蛋白组组内比较差异均有统计学意义:(F=120.455,P<0.001)、(F=165.813,P<0.001)及(F=309.346,P<0.001)。②LPS时效组:RACK1和rac1蛋白表达呈时间依赖性增加,LPS刺激24 h后达最高,各蛋白组组内比较差异均有统计学意义:(F=454.034,P<0.001)和(F=423.630,P<0.001);p-Akt表达自3 h(0.460±0.089)上调,12 h达最高(2.022±0.244),24 h(1.264±0.074)仍高于0 h(0.237±0.063),组间比较差异有统计学意义(F=137.726,P<0.001)。③IGF-1时效组:IGF-1诱导PMVEC表达RACK1、rac1及p-Akt呈时间依赖性增加,各组组间比较差异有统计学意义(F=188.293,P<0.001)、(F=115.071,P<0.001)及(F=60.175,P<0.001)。④LY294002干预组:LPS+LY294002作用PMVEC后:RACK1蛋白表达量较LPS组下调[(0.732±0.137)vs(1.498±0.167),P<0.001];rac1蛋白表达量较LPS组下调[(0.758±0.084)vs(1.384±0.170),P<0.001];p-Akt蛋白表达量较LPS组下调[(0.492±0.148)vs(1.106±0.219),P<0.001]。结论 PI3K/Akt信号通路通过干预RACK1和rac1表达,参与LPS致PMVEC损伤。

Objective To explore the effects of phosphatidylinositol 3-kinase(PI3 K)/protein kinase B(Akt) signaling pathway on the expression of receptor for activated C kinase 1(RACK1) and ras-related C3 botulinum toxin substrate 1(rac1) in rat pulmonary microvascular endothelial cells(PMVEC) induced by lipopolysaccharide(LPS). Methods Cultured rat PMVEC in vitro were divided into different groups of LPS dose-dependent group, LPS time-dependent group, IGF-1 time-dependent group and LPS+LY294002 group. ① For LPS dose-dependent group, PMVEC were cultured with 0, 1, 5, 10 mg/L LPS for 12 h. ② For LPS time-dependent group, PMVEC were cultured with 10 mg/L LPS for 0, 3, 6, 8, 12, 24 h. ③ For IGF-1 time-dependent group, PMVEC were cultured with IGF-1 for 0, 3, 6, 8, 12, 24 h. ④ For LPS+LY294002 group, PMVEC were cultured with 100 ng/ml LY294002 for 1 h before the treatment of 10 mg/L LPS for an additional 12 h. In addition, blank, LPS and LY294002 groups were set as references. After intervention, the levels of RACK1, rac1 and p-Akt were detected with Western blot. Results ① In LPS dose-dependent group, the relative expression levels of RACK1, rac1 and p-Akt increased in a dose-dependent manner, and there were significant differences among the groups of RACK1(F=120.455, P<0.001), among the groups of rac1(F=165.813, P<0.001)and among the groups of p-Akt(F=309.346, P<0.05), respectively. ② In LPS time-dependent group, the relative expression levels of RACK1 and rac1 increased in a time-dependent manner, and there were significant differences among the groups of RACK1(F=454.034, P<0.001) and among the groups of rac1(F=423.630,P<0.001), respectively. The relative expression level of p-Akt raised at 3 h(0.460±0.089), peaked at 12 h(2.022±0.244), and it was still higher at 24 h(1.264±0.074) than 0 h(0.237±0.063). There were significant differences(F=137.726, P<0.001) among the groups of p-Akt expression. ③In IGF-1 time-dependent group, the relative expression levels of RACK1, rac1 and p-Akt increased in a time-dependent manner, and there were significant differences among the groups of RACK1(F=188.293,P<0.001), rac1(F=115.071,P<0.001) and p-Akt(F=60.175,P<0.001). ④ In LPS+ LY294002 intervention group, the expression of RACK1 was lower than that of the LPS group [(0.732±0.137) vs(1.498±0.167),P<0.001], the expression of rac1 was lower than that of the LPS group [(0.758±0.084) vs(1.384±0.170),P<0.001], the expression of p-Akt was lower than that of the LPS group [(0.492±0.148) vs(1.106±0.219),P<0.001]. Conclusions PI3 K/Akt signaling pathway participates in LPS-induced PMVEC injury by interfering with RACK1 and rac1 expression.