SNHG12结合Occludin抑制其泛素化维系脑缺血应激损伤中血脑屏障结构稳态的研究

Treatment of ischemic stroke is to restore blood supply early, avoiding ischemic brain tissue necrosis. However, it will inevitably lead to reperfusion (I/R) injury. I/R can cause the destruction of the blood-brain barrier (BBB), leading to serious consequences such as vasogenic brain edema and hemorrhagic transformation. Therefore, it is important to elucidate the mechanism by which BBB integrity is impaired under I/R. We found that lncRNA SNHG12 was significantly overexpressed in brain microvascular endothelial cells (BMEC) in the early phase of I/R by high-throughput sequencing and in vitro and in vivo identification; knocking down lncRNA SNHG12 increased the permeability of HBMEC after oxygen glucose deprivation/reoxygenation treatment; lncRNA SNHG12 could bind with the tight junction protein Occludin directly, affecting its ubiquitination. Based on the previous study, our project will ascertain whether specific intervention of lncRNA SNHG12 expression in BMEC can affect BBB permeability, ischemic area, inflammation and neuron apoptosis in the I/R model; meanwhile, elucidate the mechanism of lncRNA SNHG12 in regulating Occludin distribution and degradation. The completion of this project will provide experimental evidence for clarifying the injury process of BBB in the early stage of I/R, which is expected to provide a potential target for clinical improvement on the safety of ischemia stroke treatment.

缺血性脑卒中的治疗在于早期恢复血供，避免缺血区脑组织坏死。然而，其不可避免地将导致再灌注（I/R）损伤。I/R可引起血脑屏障（BBB）的破坏，造成血管源性脑水肿和继发性出血等严重后果。因此，阐明I/R对BBB完整性损伤的机制至关重要。我们前期通过高通量测序及体内、体外鉴定发现：lncRNA SNHG12在I/R状态下的脑微血管内皮细胞（BMEC）中表达显著升高；敲降lncRNA SNHG12可致氧糖剥夺/再复氧的BMEC屏障通透性升高；且lncRNA SNHG12直接结合紧密连接蛋白Occludin抑制其泛素化。本项目将探明：特异性干预BMEC中lncRNA SNHG12对I/R模型中BBB的通透性、缺血区炎症反应及神经元凋亡等的影响；同时阐明lncRNA SNHG12调节Occludin蛋白定位与降解的机制。本项目将增进对BBB损伤过程的认知，可望为提高卒中治疗安全性提供潜在靶点。

血脑屏障（Blood-brain barrier，BBB）是维持脑内微环境稳态的结构和功能性屏障。血脑屏障的稳态失衡以及完整性损伤是众多中枢神经系统相关疾病（脑卒中、多发硬化、脑肿瘤、阿尔茨海默症等）的关键病理生理学特征。目前，相较于血脑屏障的发育形成过程，对于血脑屏障在成体以及病理状态下的稳态维持研究相对滞后，因此，阐明血脑屏障稳定性维持机制对于理解及干预脑卒中等中枢神经系统相关疾病的病理损伤过程至关重要。. 在本课题的资助下，申请人新近发现一个高度保守的细胞膜定位长链非编码RNA（SNHG12）能够参与血脑屏障构成。SNHG12能够与紧密连接蛋白Occludin的N-末端直接结合，封闭Occludin上泛素连接酶Itch的结合位点，从而阻止Occludin的异常内化、降解，维持了血脑屏障稳态。并发现其生理学意义是维持血脑屏障的氧适应性稳态，因为缺氧显著加剧了小鼠脑内皮Snhg12敲除所引起的血脑屏障渗漏和小鼠认知等行为学改变。该研究成果不仅延伸了血脑屏障的组成成分概念，而且也为缺氧环境下所引起的血脑屏障损害的预防提供了新的药物靶点。目前，项目负责人作为独立第一作者，已将该研究成果以“An oxygen-adaptive interaction between SNHG12 and Occludin maintains blood brain barrier integrity”为题发表于Cell子刊Cell Reports（Cell Rep. 2022 Apr 12;39(2):110656.）。