MicroRNA302-367簇调控线粒体自噬抗菌的分子机制研究

Pseudomonas aeruginosa is an important opportunistic pathogen, which is one of the major causes of pulmonary infection. Once acquired and colonized in the respiratory tract or lung, this bacterium is extremely difficult to eradicate. MicroRNAs and mitophagy has recently been implicated in bacterial infection, but how the microRNAs regulating host mitophagy in response to bacterial infection remains largely unknown. .In our previous work, we observed that microRNA302-367 cluster effectively enhanced clearance of invading P. aeruginosa by macrophage. In this project, we intend to study the following contents: observing the induction of host mitophagy by microRNA302-367 cluster to enhance its ability to eliminate P. aeruginosa through detecting the expression of specific mitophagy receptor and the level of mitophagic activity in MH-S macrophage model and in mouse model with respiratory tract infection; to explore the specific mechanism and molecular signal transduction pathways of microRNA302-367 cluster by targeting specific genes and regulating host mitophagy in response to the invasion of P. aeruginosa, and to demonstrate the key role of microRNA302-367 cluster in the regulation of bacterial clearance. .The successful implementation of this project will enrich our limited knowledge on the biological process and pathogenesis of bacterial pulmonary infection, and provide novel targets and new strategies for the development of antimicrobial agents.

铜绿假单胞菌是临床常见的条件致病菌，是导致细菌性肺部(呼吸道)感染的主要诱因之一，一旦宿主受到感染，这种细菌很难被根除。虽然已有研究证明microRNAs和线粒体自噬与应对细菌感染有关，但microRNAs是否或如何调控宿主线粒体自噬应对细菌感染的基本机制仍有待阐明。本课题组前期研究已初步探明了microRNA302-367簇能有效增强巨噬细胞清除不同铜绿假单胞菌菌株的能力，本项目拟在MH-S巨噬细胞模型和小鼠肺部细菌感染模型上，以特异线粒体自噬受体表达及线粒体自噬活性变化为主要指标，深入探讨microRNA302-367簇通过靶向目的基因来调控宿主线粒体自噬应对铜绿假单胞菌入侵的具体机制，并诠释microRNA302-367簇在细菌清除中的关键调控作用。本项目的顺利实施将加深我们对细菌性肺部感染形成的生物学过程和致病机制的认识，也将为临床抗菌药物的开发提供更好的靶标和防治新策略。

背景：铜绿假单胞菌是重要的临床条件致病菌，常导致严重的细菌性肺部感染。有研究表明microRNAs参与细菌感染调控，但microRNAs如何调控宿主线粒体自噬应对细菌感染的机制仍未阐明。. 研究内容与方法：本项目在MH-S巨噬细胞模型和小鼠肺部细菌感染模型上，以特异线粒体自噬受体（PHB2）表达及线粒体自噬活性变化为主要指标，结合微生物学、分子生物学、细胞生物学、生物信息学、免疫学和生物化学等多种学科的方法深入探讨了mir-302/367簇通过靶向目的基因来调控宿主线粒体自噬应对铜绿假单胞菌入侵的具体机制和诠释mir-302/367簇在细菌清除中的调控作用。. 结果：我们的研究表明，mir-302/367簇的表达量在铜绿假单胞菌感染后明显升高。在巨噬细胞中，mir-302/367簇的过表达促进了线粒体自噬和调控ROS的生成，从而促进了细胞内铜绿假单胞菌的消除。在小鼠肺部感染模型中，我们也发现经过mir-302a和mir-302b模拟物处理的小鼠能显著减低肺部的荷菌量。重要的是，我们通过生物信息学还鉴定出NF-κB可作为mir-302/367簇的新靶标，miR-302/367簇通过调控ROS/NF-κB的生成来促进线粒体自噬介导的细菌清除能力，从而维持胞内的稳态。. 结论：本项目的实施加深了我们对细菌性肺部感染形成的生物学过程和致病机制的认识，同时，本研究发现的将miRNAs和宿主线粒体自噬作为潜在靶标的方法可以为未来的临床药物开发提供一个很好的思路，从而更好地应对由铜绿假单胞菌引起的疾病。