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目的探讨高氧暴露后早产鼠肺组织Wnt7b和β-连环蛋白(β-catenin)水平变化,高氧、降钙素基因相关肽(CGRP)干预后Wnt通路下游基因转录调控因子T细胞因子(TCF)、靶基因c-myc mRNA的表达,了解Wnt信号转导途径是否参与了氧化应激导致的肺泡Ⅱ型内皮细胞(AECⅡ)损伤死亡和肺发育障碍,以及其与CGRP肺保护作用的关系。方法 western blot检测95%高氧暴露早产鼠肺组织及高氧、CGRP干预后原代AECⅡWnt7b、β-catenin蛋白水平,RT-PCR测定TCF及c-myc mRNA表达。结果高氧暴露后3天肺组织Wnt7b及β-catenin蛋白表达即较空气对照组显著增强(P<0.05),7天时蛋白水平达到峰值,14天时表达有所下降,但仍明显高于空气对照组(P<0.05)。与空气对照组比较,高氧组AECⅡTCF及c-myc mRNA表达明显增强(P<0.01),高氧+CGRP组较单纯高氧组TCF、c-myc mRNA表达水平升高更为显著(P<0.01),空气+CGRP组TCF、c-myc mRNA表达与空气对照组差异无统计学意义(P>0.05)。结论高氧暴露后Wnt7b/β-catenin信号通路激活,启动下游增殖相关基因转录,可能是氧化应激性肺损伤时AECⅡ自我修复的机制之一。CGRP可促进Wnt7b/β-catenin活化,Wnt7b/β-catenin信号转导途径可能参与了CGRP的肺保护作用。
Objective To investigate the changes of Wnt7b and β-catenin in the lung tissue of premature rats after hyperoxia exposure. The effects of high oxygen and calcitonin gene-related peptide (CGRP) on the expression of downstream transcriptional regulatory factors T-cell factor (TCF) ), The expression of c-myc mRNA and the Wnt signaling pathway were involved in the oxidative stress-induced injury and pulmonary dysplasia of pulmonary alveolar type 2 endothelial cells (AECII) and their relationship with lung protective effect of CGRP. Methods Western blot was used to detect the expression of primary AECⅡWnt7b and β-catenin in lung tissue and hyperoxia after 95% hyperoxia exposure and the expression of TCF and c-myc mRNA by RT-PCR. Results The protein expression of Wnt7b and β-catenin in lung tissue was significantly increased 3 days after hyperoxia exposure (P <0.05), and reached the peak at 7th day. The expression of Wnt7b and β-catenin decreased significantly at 14th day but was still significantly higher than that of air control Group (P <0.05). Compared with air control group, the expression of AECⅡTCF and c-myc mRNA in hyperoxia group was significantly increased (P <0.01), while the expression of TCF and c-myc mRNA in hyperoxia + CGRP group was more significant than that in hyperoxia group (P < 0.01). The expressions of TCF and c-myc mRNA in air + CGRP group were not significantly different from those in air control group (P> 0.05). Conclusions Activation of Wnt7b / β-catenin signaling pathway after hyperoxia exposure initiates transcription of downstream proliferation-related genes, which may be one of the mechanisms of AECⅡs self-repair during oxidative stress lung injury. CGRP can promote the activation of Wnt7b / β-catenin, Wnt7b / β-catenin signal transduction pathway may be involved in the lung protection of CGRP.