PI3K/SGK1信号通路上调小鼠肺上皮钠通道表达的研究

PI3K/SGK1 signaling pathway up-regulates expression of sodium channel in mouse alveolar epithelium

目的:探讨磷酯酰肌醇3-激酶(PI3K)/血清-糖皮质激素调节激酶1(SGK1)信号通路对小鼠肺上皮钠通道(ENaC)表达的影响。方法:24只健康成年C3H/HeN小鼠随机分为对照组、急性肺损伤(ALI)组、胰岛素组和PI3K siRNA组,每组6只。收集支气管肺泡灌洗液(BALF),测量肺泡液体清除率(AFC),免疫荧光测定ENaC各亚基。培养原代小鼠肺泡上皮II型细胞,分别转染PI3K siRNA和SGK1 siRNA,RT-PCR法测定ENaC的mRNA表达,Western blot法测定ENaC蛋白表达和SGK1磷酸化水平。结果:与ALI组比较,胰岛素组AFC和ENaC各亚基表达均显著增加(P<0.05)。与胰岛素组比较,PI3K siRNA组AFC和ENaC各亚基表达均显著减少(P<0.05)。与胰岛素干预比较,肺泡上皮细胞分别转染PI3K siRNA和SGK1 siRNA后,ENaC各亚基的mRNA和蛋白表达显著减少(P<0.05),SGK1磷酸化水平显著降低(P<0.05)。结论:激活PI3K/SGK1信号通路通过上调小鼠肺ENaC各亚基的表达,增强AFC,从而减轻小鼠ALI。

AIM:To investigate the effect of phosphatidylinositol 3-kinase(PI3 K)/serum-glucocorticoid regulated kinase 1(SGK1)signaling pathway on the expression of alveolar epithelial sodium channel(ENaC)in mice.METHODS:Twenty-four healthy adult C3 H/HeN mice were randomly divided into control group,acute lung injury(ALI)group,insulin group and PI3 K siRNA group,with 6 mice in each group. Bronchoalveolar lavage fluid(BALF)was collected and alveolar fluid clearance(AFC)was measured. Each subunit of ENaC was determined by immunofluorescence. Primary mouse alveolar epithelial type II cells were cultured and transfected with PI3 K siRNA or SGK1 siRNA.The mRNA expression of ENaC was measured by RT-PCR. The ENaC protein expression and SGK1 phosphorylation were determined by Western blot.RESULTS:Compared with ALI group,AFC and the expression of ENaC subunits in insulin group were significantly increased(P<0. 05). Compared with insulin group,AFC and the expression of ENaC subunits in PI3 K siRNA group were significantly decreased(P<0. 05). Compared with insulin group,the mRNA and protein expression levels of ENaC subunits were significantly decreased in PI3 K siRNA-or SGK1 siRNA-transfected alveolar epithelial cells(P<0. 05),and SGK1 phosphorylation level was also significantly decreased(P<0. 05).CONCLUSION:Activation of PI3 K/SGK1 signaling pathway can enhance AFC and alleviate lung injury by up-regulating the expression of ENaC in mouse lung tissues.