Tan Hao-Yu, Qing Bei, Luo Xian-Mei, Liang Heng-Xing
Department of Cardio-vascular Surgery, the Second Xiangya Hospital of Central South University, No.139 Middle Renmin Road, Hunan Province, 410011, Changsha, People's Republic of China.
Department of Thoracic Surgery, the Second Xiangya Hospital of Central South University, No.139 Middle Renmin Road, Hunan Province, 410011, Changsha, People's Republic of China.
J Inflamm (Lond). 2021 Nov 3;18(1):29. doi: 10.1186/s12950-021-00295-3.
Excessive autophagic activity in alveolar epithelial cells is one of the main causes of acute lung injury (ALI), but the underlying molecular mechanism has not been fully elucidated. Previous studies have shown that microRNAs (miRs) are involved in regulating autophagy in several diseases. This study aimed to determine the role of miR-223 in excessive autophagic activity in alveolar epithelial cells and the underlying mechanism to identify a novel therapeutic targets for the development of new drugs to treat acute respiratory distress syndrome (ARDS).
A549 cells were treated with lipopolysaccharide (LPS) to establish an ALI in vitro model. The expression of miR-223 and its role of miR-223 in regulating oxidative stress and autophagy in the LPS-treated A549 cells, were examined using RT-PCR, flow cytometry and ELISA. A luciferase reporter assay was performed to verify the interaction between miR-223 and the high-mobility group box 2 (HMGB2) protein.
The results showed that the LPS treatment downregulated miR-223 expression in alveolar epithelial cells. We further proved that miR-223 directly targeted the 3-untranslated region of the HMGB2 gene and the downregulation of miR-223 increased HMGB2 protein level, which activated the JNK signalling pathway and thus induced oxidative stress and autophagy in LPS-treated alveolar epithelial cells. Knockdown of HMGB2 protein deactivated the JNK signalling pathway and inhibited autophagy and oxidative stress in alveolar epithelial cells.
The results of this study suggest that miR-223 regulates oxidative stress and autophagy in alveolar epithelial cells by targeting HMGB2 via the JNK signalling pathway.
肺泡上皮细胞中自噬活性过高是急性肺损伤（ALI）的主要原因之一，但其潜在分子机制尚未完全阐明。先前研究表明，微小RNA（miRs）参与多种疾病中自噬的调节。本研究旨在确定miR-223在肺泡上皮细胞自噬活性过高中的作用及其潜在机制，以寻找新的治疗靶点，用于开发治疗急性呼吸窘迫综合征（ARDS）的新药。
用脂多糖（LPS）处理A549细胞，建立体外ALI模型。采用逆转录聚合酶链反应（RT-PCR）、流式细胞术和酶联免疫吸附测定（ELISA）检测miR-223的表达及其在LPS处理的A549细胞中调节氧化应激和自噬的作用。进行荧光素酶报告基因检测以验证miR-223与高迁移率族蛋白B2（HMGB2）蛋白之间的相互作用。
结果显示，LPS处理下调了肺泡上皮细胞中miR-223的表达。我们进一步证明，miR-223直接靶向HMGB2基因的3'非翻译区，miR-223的下调增加了HMGB2蛋白水平，激活了JNK信号通路，从而在LPS处理的肺泡上皮细胞中诱导氧化应激和自噬。敲低HMGB2蛋白可使JNK信号通路失活，并抑制肺泡上皮细胞中的自噬和氧化应激。
本研究结果表明，miR-223通过JNK信号通路靶向HMGB2来调节肺泡上皮细胞中的氧化应激和自噬。
