环状RNA FOXO3在COPD进程中的作用机制研究

circRNA is abundant in human transcriptome, but its effect in chronic obstructive pulmonary disease (COPD) development remain unreported. In our preliminary study, we found that circFOXO3 was significantly down-regulated in the lung tissues from COPD compared with NS using circRNA microarray and qRT-PCR, and positively correlated with the severity of airflow obstruction. Overexpression of circFOXO3 remarkably inhibited inflammatory cytokines levels and inflammatory response induced by cigarette smoke (CS) and cigarette smoke exact (CSE). Mechanistic investigations defined that circFOXO3 is observed to sponge to miR-214 with a potential binding site, thereby reducing miR-214 ability to target mRNAs using miRanda prediction algorithm and circRIP assay. Based on above findings, we speculate that circFOXO3 may serve as a miRNA sponge for miR-214 regulating PTEN/AKT pathway or directly binding to some proteins involved in COPD development and progression. We further determine the functional mechanism of circFOXO3/miR-214 or circFOXO3 binding protein in COPD development and progression, and analyze the association of circFOXO3, miR-214 and target-binding protein expression with the clinicopathological characteristics of COPD patients. In addition, we will examine the levels of circFOXO3 in plasma and sputum of COPD patients. Collectively, our study will help to clarify the functional mechanism of circFOXO3 in COPD development and progression, and provide new markers for clinical diagnosis and treatment for COPD.

环状RNA在人类转录组中大量存在，但是否参与慢性阻塞性肺病（COPD）的进程未见报道。我们前期发现肺组织circFOXO3低表达与COPD患者肺功能下降呈显著正相关。circFOXO3过表达显著抑制烟熏（CS）及香烟提取物（CSE）诱导的炎症因子表达和炎症反应。研究表明：circFoxo3与miR-214富集，从而降低miR-214与其它靶基因的结合能力。据此我们推测：circFOXO3可能通过结合miR-214，调控其下游PTEN/AKT通路，也可能通过结合并影响目标蛋白，参与调控COPD的进程。本研究将结合分子生物学、细胞生物学和免疫学等技术，进一步探索circFOXO3对miR-214及目标结合蛋白的调控机制。此外，我们将分析患者血浆和痰液中circFOXO3的表达在COPD诊断中的应用价值。本研究将阐述circFOXO3在COPD进程中的作用机制，为COPD诊断及治疗提供新型靶点。

慢性阻塞性肺疾病（COPD）是一种常见的慢性气道炎症性疾病。环状RNA（circRNAs）与炎症调节有关。因此，本课题开展了circFOXO3在COPD气道炎症和细胞衰老中的作用及相关机制研究。通过实验我们发现：（1）circFOXO3在CS暴露的肺和香烟烟雾提取物（CSE）处理的小鼠肺泡上皮细胞MLE12中表达上调。circFOXO3的抑制减弱了CS暴露小鼠肺部CXCL1和IL-6的释放以及炎症过程。miR-214-3p被鉴定为circFOXO3靶向的microRNA。circFOXO3沉默下调了IKK-β mRNA (miR-214-3p的靶标)，导致NF-κB信号通路功能障碍，CSE诱导的炎症细胞因子表达减弱。(2) CS诱导的circFOXO3上调直接与E2F1相互作用，通过抑制自噬增强AT2细胞衰老。总之，这些结果揭示了circFOXO3在CS诱导的肺损伤相关病理重塑中的关键功能。因此，抑制circFOXO3可能是CS诱导的肺损伤的有效治疗策略。