Jin Linlin, Yang Haiping, Fu Jianhua, Xue Xindong, Yao Li, Qiao Lin
Department of Pediatrics, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China.
Mol Med Rep. 2015 Jun;11(6):4079-86. doi: 10.3892/mmr.2015.3339. Epub 2015 Feb 12.
Previous studies have demonstrated that oxidative stress‑induced lung injury is involved in the occurrence and developmental process of bronchopulmonary dysplasia (BPD). The present study assessed whether oxidative DNA damage occurs in the early stages of hyperoxia‑induced BPD in neonatal rats and evaluated the expression and localization of the DNA repair gene, 8‑oxoguanine DNA glycosylase 1 (OGG1), upon exposure to hyperoxia. Neonatal rats and primary cultured neonatal rat alveolar epithelial type II (AECII) cells were exposed to hyperoxia (90% O2) or normoxia (21% O2) and the expression levels of 8‑hydroxy‑2'‑deoxyguanosine (8‑OHdG) in the lung tissues and AECII cells were determined using a competitive enzyme‑linked immunosorbent assay. DNA strand breaks in the AECII cells were detected using a comet assay. The expression and localization of the OGG1 protein in the lung tissues and AECII cells were determined by immunofluorescence confocal microscopy and western blotting. The mRNA expression levels of OGG1 in the lung tissues and AECII cells were determined by reverse transcription polymerase chain reaction. The expression of 8‑OHdG was elevated in the hyperoxia‑exposed neonatal rat lung tissue and the AECII cells compared with the normoxic controls. The occurrence of DNA strand breaks in the AECII cells increased with increasing duration of hyperoxia exposure. The protein expression of OGG1 was significantly increased in the hyperoxia‑exposed lung tissues and AECII cells, with OGG1 preferentially localized to the cytoplasm. No concomitant increase in the mRNA expression of OGG1 was detected. These results revealed that oxidative DNA damage occurred in lung epithelial cells during early‑stage BPD, as confirmed by in vitro and in vivo hyperoxia exposure experiments, and the increased expression of OGG1 was associated with this process.
先前的研究表明，氧化应激诱导的肺损伤参与了支气管肺发育不良（BPD）的发生和发展过程。本研究评估了新生大鼠高氧诱导的BPD早期是否发生氧化DNA损伤，并评估了暴露于高氧环境下DNA修复基因8-氧代鸟嘌呤DNA糖基化酶1（OGG1）的表达和定位。将新生大鼠和原代培养的新生大鼠肺泡II型上皮细胞（AECII）暴露于高氧（90% O2）或常氧（21% O2）环境中，采用竞争性酶联免疫吸附测定法测定肺组织和AECII细胞中8-羟基-2'-脱氧鸟苷（8-OHdG）的表达水平。采用彗星试验检测AECII细胞中的DNA链断裂情况。通过免疫荧光共聚焦显微镜和蛋白质印迹法测定肺组织和AECII细胞中OGG1蛋白的表达和定位。采用逆转录聚合酶链反应测定肺组织和AECII细胞中OGG1的mRNA表达水平。与常氧对照组相比，暴露于高氧的新生大鼠肺组织和AECII细胞中8-OHdG的表达升高。AECII细胞中DNA链断裂的发生率随高氧暴露时间的延长而增加。暴露于高氧的肺组织和AECII细胞中OGG1的蛋白表达显著增加，OGG1优先定位于细胞质。未检测到OGG1的mRNA表达伴随增加。这些结果表明，通过体外和体内高氧暴露实验证实，在BPD早期肺上皮细胞中发生了氧化DNA损伤，且OGG1表达增加与这一过程相关。
