miR-125b通过p53-Drp1通路调节线粒体动力学缓解脓毒症相关性脑病的机制研究

Mitochondrial dysfunction plays a vital role in neuronal apoptosis and cognitive dysfunction in sepsis-associated encephalopathy (SAE), but the exact mechanism remains unknown. Our previous study showed that miR-125b was down-regulated, while p53 and mitochondrial division-related protein 1 (Drp1) were up-regulated in SAE. Inhibition of Drp1 could rescue SAE-induced brain dysfunction; upregulation of miR-125b could relieve mitochondrial damage, neuronal apoptosis and cognitive dysfunction in SAE. Considering that Drp1 recruits p53 to bind on mitochondria to regulate cellular functions under oxidative stress, we hypothesize that miR-125b ameliorates SAE-induced brain dysfunctions via p53-Drp1 pathway. We will use different SAE models and sophisticated technologies including cryo-microscopy in this project. Firstly, we will investigate the mitochondrial dynamics in SAE, and then we will study the protective effect of miR-125b on brain dysfunction of SAE. Furthermore we will identify whether miR-125b plays the neuroprotective role via regulating mitochondrial dynamics relying on p53-Drp1 pathway. This project will identify the protective effect and mechanism of miR-125b on SAE-induced brain dysfunction via regulating mitochondrial functions, which will provide new therapeutic targets and theoretical basis for prevention and treatment of SAE-induced brain dysfunction.

线粒体功能障碍是导致脓毒症相关性脑病（SAE）中神经元凋亡和认知功能障碍的重要原因，但机制尚不清楚。我们前期研究发现在SAE中，miR-125b下调，而p53和线粒体分裂相关蛋白(Drp1)上调；干预Drp1可缓解SAE，上调miR-125b后可降低p53与Drp1表达，缓解SAE线粒体损伤。因为在氧化应激下Drp1可募集p53到线粒体引起线粒体损伤。据此我们提出假设：miR-125b通过下调p53和Drp1保护线粒体功能从而缓解SAE功能障碍。本课题将利用不同SAE模型，首先明确SAE中的线粒体功能障碍，然后研究miR-125b对SAE脑功能保护作用，进一步探讨miR-125b/p53-Drp1通路调控线粒体功能进而保护神经元的机制。完成本项目将深入明确miR-125b通过线粒体途径对SAE诱发的脑功能障碍的保护作用及其分子机制，为诊断和防治SAE提供新理论依据和治疗靶点。

脓毒症相关性脑病（SAE）为脓毒症并发的短期弥漫性大脑功能障碍和长期不可逆认知功能损伤。本研究主要探索microRNA-125b（miR-125b）在 SAE 发生机制中的调节作用及其机制。体外实验部分，本研究使用双氧水刺激小鼠海马神经元细胞（HT22）模型。通过过表达miR-125b、同时过表达miR-125b及p53，研究miR-125b/p53通路对小鼠海马神经元细胞（HT22）线粒体的保护机制。该部分研究表明，过表达miR-125b缓解双氧水所致的HT22线粒体分裂和融合蛋白变化、线粒体损伤、ROS产生增多及死亡。体内实验部分，本研究使用盲肠结扎穿孔（CLP）的小鼠模型。通过过表达miR-125b、同时过表达miR-125b及p53，研究miR-125b/p53通路对CLP小鼠的认知功能的保护机制。该部分研究表明，miR-125b通过抑制p53的表达，可缓解CLP诱导的小鼠海马神经元线粒体功能障碍，改善线粒体形态学异常，减轻CLP诱导的小鼠空间记忆能力下降等认知功能损害。本研究在细胞和动物模型中，在分子生物学、细胞器、细胞、组织、动物多个水平，全面研究了miR-125b在SAE中的作用及调控机制，具有重要的科学意义。