摘要
目的 探讨脂氧素A4(lipoxin A4,LXA4)通过let-7c基因/转化生长因子 β1(transforming growth factor-β1,TGF-β1)信号通路保护高氧损伤小鼠肺上皮细胞MLE-12的作用机制.方法 体外传代培养MLE-12细胞,待其生长至接近融合状态时,随机分为高氧空白组、LXA4组、let-7c过表达组、let-7c沉默组、let-7c沉默+LXA4组.各实验组均暴露于85%氧气中,LXA4组给予LXA4干预,let-7c过表达组和let-7c沉默组分别利用脂质体3000转染建立let-7c过表达或let-7c沉默细胞株.let-7c沉默+LXA4组给予LXA4干预let-7c沉默细胞株.实时荧光定量聚合酶链反应检测细胞外基质,包括 α-平滑肌肌动蛋白(α-smooth muscle actin,α-SMA)、Ⅰ型胶原(collagenⅠ,COL-Ⅰ)、TGF-β1信号通路及相关下游基因Smad 2、Smad 3、Smad 4、转化生长因子β1受体(TGF-βR1)、转化生长因子 β2受体(TGF-βR2)mRNA水平.Western blot检测TGF-β1信号蛋白Smad 2、Smad 3、Smad 4、p-Smad 2、p-Smad 3和TGF-βR1的表达.结果 LXA4组和let-7c过表达组细胞α-SMA、COL-Ⅰ、Smad 3、Smad 4、TGF-βR1、TGF-βR2 mRNA(×10-4)[LXA4组:(24.3±2.1)、(14.6±0.2)、(17.0±0.0)、(14.9±0.1)、(20.8±0.1)、(9.0±0.0),let-7c过表达组:(12.2±0.5)、(3.0±0.0)、(3.1±0.0)、(9.6±0.4)、(28.5±0.2)、(7.6±0.1)]低于高氧空白组[(51.4±0.5)、(32.0±0.1)、(40.6±0.2)、(16.3±0.1)、(89.1±1.1)、(19.3±0.2)],let-7c沉默组和let-7c沉默+LXA4组[let-7c沉默组:(87.3±7.0)、(38.5±0.3)、(48.0±0.2)、(56.5±0.2)、(126.0±0.9)、(33.1±1.0),let-7c沉默+LXA4组:(144.5±12.9)、(86.3±3.0)、(91.5±4.7)、(86.5±3.3)、(109.0±4.5)、(45.6±1.6)]高于高氧空白组;LXA4组和let-7c过表达组细胞Smad 2、Smad 3、Smad 4、p-Smad 2、p-Smad 3、TGF-βR1蛋白低于高氧空白组,let-7c沉默+LXA4组p-Smad 2、p-Smad 3高于高氧空白组,差异均有统计学意义(P〈0.05).结论 LXA4可能通过let-7c/TGF-β1信号通路发挥对高氧损伤小鼠肺上皮细胞的保护作用.
Objective To study the protective mechanisms of lipoxin A 4 ( LXA4 ) for hyperoxia-induced lung injury through modulation of let-7c/TGF-β1 signal pathway in mice.Method MLE-12 cells was transfected with let-7c mimic, mimic negative control ( NC) , let-7c inhibitor and inhibitor NC.The cells were assigned into hyperoxia group , LXA4 group, let-7c over-expression group, let-7c silence group, let-7c silence+LXA4 group, and all exposed to 85% oxygen.The mRNA level of the extracellular matrixα-smooth muscle actin (α-SMA) and collagen Ⅰ( COL-Ⅰ) , and the expression of related genes in TGF-β1 signaling pathway (Smad 2, Smad 3, Smad 4, TGF-βR1, TGF-βR2) were examined using qPCR.The protein expressions in TGF-β1 signaling pathway was examined using Western blot .Result The mRNA expressions of α-SMA, COL-Ⅰ, Smad 3, Smad 4, TGF-βR1 and TGF-βR2 in LXA4 group [(24.3 ±2.1), (14.6 ±0.2), (17.0 ±0.0), (14.9 ±0.1), (20.8 ±0.1), (9.0 ±0.0) ] and let-7c over-expression group [ ( 12.2 ±0.5 ) , ( 3.0 ±0.0 ) , ( 3.1 ±0.0 ) , ( 9.6 ±0.4 ) , ( 28.5 ±0.2 ) , ( 7.6 ± 0.1)] were decreased comparing with the hyperoxia group [(51.4 ±0.5), (32.0 ±0.1), (40.6 ±0.2), (16.3 ±0.1), (89.1 ±1.1), (19.3 ±0.2)].These expressions were increased in both let-7c silence group [(87.3 ±7.0), (38.5 ±0.3), (48.0 ±0.2), (56.5 ±0.2), (126.0 ±0.9), (33.1 ±1.0)] and let-7c silence +LXA4 group [(144.5 ±12.9), (86.3 ±3.0), (91.5 ±4.7), (86.5 ±3.3), (109.0 ±4.5), (45.6 ±1.6)].The protein levels of Smad 2, Smad 3, Smad 4, p-Smad 2, p-Smad 3 and TGF-βR1 of LXA4 group and let-7c over-expression group were decreased comparing with the hyperoxia group, while p-Smad 2, p-Smad 3 of let-7c silence+LXA4 group were increased(P〈0.05).Conclusion LXA4 may play a protective role through let-7c /TGF-β1 signal pathway of lung epithelial cells for hyperoxia-induced lung injury in mice .
基金
国家自然科学基金(81300521)
江苏省六大高峰人才项目(WSN-090)