Department of Pediatrics, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu, 212000, People's Republic of China.
BMC Pulm Med. 2021 Nov 22;21(1):379. doi: 10.1186/s12890-021-01751-9.
Bronchopulmonary dysplasia (BPD) is a major cause of mortality and morbidity in premature infants, characterized by alveolar dysplasia and pulmonary microvascular remodeling. In the present study, we have investigated the functional roles of ubiquitin proteasome pathway (UPP) in BPD, and its relationship with endoplasmic reticulum stress (ERS) mediated type II alveolar epithelial cell (AECII) apoptosis.
A hyperoxia-induced BPD rat model was constructed and the pathologic changes of lung tissues were evaluated by hematoxylin-eosin staining. Cell apoptosis and protein expression were determined by TUNEL assay and Western blotting, respectively. Further reagent kit with specific fluorescent substrate was utilized to measure the activity of 20 s proteasome. Meanwhile, AECII were cultured in vitro and exposed to hyperoxia. AECII apoptosis were measured by flow cytometry. In contrast, MG132 treatment was induced to explore UPP during hyperoxia exposure on AECII apoptosis and ERS sensors expression.
A significant increase in apoptosis and total ubiquitinated proteins expression were observed in BPD rats and AECII culture, and the change of UPP was associated with ERS. In order to confirm the role of UPP in AECII apoptosis of BPD, AECII cells were treated by MG132 with the concentration of 10 μmol/L under hyperoxia exposure. We found that the proteins expression of glucose-regulated protein 78 (GRP-78), PKR-like ER kinase (PERK), activating transcription factor 4 (ATF4), activating transcription factor 6 (ATF6) and C/EBP homologous protein (CHOP), as well as AECII apoptosis were increased following MG132 treatment. Furthermore, the relatively up-regulated in the levels of total ubiquitinated proteins expression and 20 s proteasome activity were correlated with increased ERS sensors expression.
Our findings indicate that UPP may participate in the ERS-induced AECII apoptosis under hyperoxia condition.
支气管肺发育不良（BPD）是早产儿死亡和发病的主要原因，其特征为肺泡发育不良和肺微血管重塑。本研究探讨了泛素蛋白酶体通路（UPP）在 BPD 中的功能作用及其与内质网应激（ERS）介导的 II 型肺泡上皮细胞（AECII）凋亡的关系。
构建高氧诱导的 BPD 大鼠模型，通过苏木精-伊红染色评估肺组织的病理变化。通过 TUNEL 检测和 Western blot 分别测定细胞凋亡和蛋白表达。进一步利用具有特定荧光底物的试剂盒测定 20S 蛋白酶体的活性。同时，体外培养 AECII 并暴露于高氧中。通过流式细胞术测定 AECII 凋亡。相反，诱导 MG132 处理以探讨 UPP 在高氧暴露对 AECII 凋亡和 ERS 传感器表达的影响。
BPD 大鼠和 AECII 培养中观察到凋亡和总泛素化蛋白表达显著增加，UPP 的变化与 ERS 相关。为了证实 UPP 在 BPD 中 AECII 凋亡中的作用，用浓度为 10μmol/L 的 MG132 处理 AECII 细胞，在高氧暴露下。我们发现，葡萄糖调节蛋白 78（GRP-78）、PKR 样内质网激酶（PERK）、激活转录因子 4（ATF4）、激活转录因子 6（ATF6）和 C/EBP 同源蛋白（CHOP）的蛋白质表达以及 AECII 凋亡均在 MG132 处理后增加。此外，总泛素化蛋白表达和 20S 蛋白酶体活性的相对上调与 ERS 传感器表达的增加相关。
我们的研究结果表明，UPP 可能参与高氧诱导的 ERS 诱导的 AECII 凋亡。
