Department of Pediatrics, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China.
Int J Mol Med. 2018 Apr;41(4):2339-2349. doi: 10.3892/ijmm.2018.3413. Epub 2018 Jan 23.
Previous studies by our group have confirmed excessive transdifferentiation of alveolar epithelial cells (AECs) in a hyperoxia‑induced bronchopulmonary dysplasia (BPD) model, but the underlying mechanism have remained elusive. The transcription factor zonula occludens 1‑associated nucleic acid binding protein (ZONAB) has the biological functions of inhibition of epithelial cell differentiation and promotion of epithelial cell proliferation. The aim of the present study was to explore the regulatory effect of ZONAB on the transdifferentiation and proliferation of AECs in a model of hyperoxia‑induced lung injury. Newborn Wistar rats were randomly allocated to a model group (inhalation of 85% O2) or a control group (inhalation of normal air), and ZONAB expression in lung tissues was detected at different time‑points. Type II AECs (AEC II) isolated from normal newborn rats were primarily cultured under an atmosphere of 85 or 21% O2, and ZONAB expression in the cells was examined. The primary cells were further transfected with ZONAB plasmid or small interfering (si)RNA and then exposed to hyperoxia, and the indicators for transdifferentiation and proliferation were measured. The present study indicated that ZONAB expression in AEC II of the BPD rats was significantly decreased from 7 days of exposure to hyperoxia onwards. In the AEC II isolated from normal neonatal rats, ZONAB expression in the model group was also reduced compared with that in the control group. After transfection with the plasmid pCMV6‑ZONAB, the expression of aquaporin 5 (type I alveolar epithelial cell marker) decreased and the expression of surfactant protein C (AEC II marker), proliferating‑cell nuclear antigen and cyclin D1 increased, which was opposite to the effects of ZONAB siRNA. Transfection with pCMV6‑ZONAB also alleviated excessive transdifferentiation and inhibited proliferation of AEC II induced by hyperoxia treatment. These results suggest that ZONAB expression in AEC II decreases under hyperoxia conditions, which promotes transdifferentiation and inhibits proliferation of AECs. This may, at least in part, be the underlying mechanism of lung epithelial injury in the hyperoxia-induced BPD model.
先前本课题组的研究已证实，在高氧诱导的支气管肺发育不良（BPD）模型中，肺泡上皮细胞（AEC）过度转分化，但具体机制仍不清楚。紧密连接相关的闭合蛋白 1 相关核酸结合蛋白（ZONAB）作为一种转录因子，具有抑制上皮细胞分化和促进上皮细胞增殖的生物学功能。本研究旨在探讨 ZONAB 对高氧诱导肺损伤模型中 AEC 转分化和增殖的调控作用。将新生 Wistar 大鼠随机分为模型组（吸入 85% O2）或对照组（吸入正常空气），并于不同时间点检测肺组织中 ZONAB 的表达。原代培养正常新生大鼠的 II 型 AEC（AEC II），在 85%或 21% O2 条件下培养，检测细胞中 ZONAB 的表达。进一步将 ZONAB 质粒或小干扰（si）RNA 转染原代细胞，然后暴露于高氧环境中，检测转分化和增殖指标。本研究表明，BPD 大鼠 AEC II 中 ZONAB 的表达从暴露于高氧 7 天开始明显下降。在正常新生大鼠分离的 AEC II 中，模型组 ZONAB 的表达也低于对照组。转染 pCMV6-ZONAB 质粒后，水通道蛋白 5（I 型肺泡上皮细胞标志物）的表达减少，表面活性蛋白 C（AEC II 标志物）、增殖细胞核抗原和细胞周期蛋白 D1 的表达增加，与 ZONAB siRNA 的作用相反。转染 pCMV6-ZONAB 还减轻了高氧处理引起的 AEC II 过度转分化和增殖抑制。这些结果表明，AEC II 中 ZONAB 的表达在高氧条件下降低，促进 AEC 的转分化和抑制增殖。这至少部分可能是高氧诱导的 BPD 模型中肺上皮损伤的潜在机制。
