脑创伤后内质网与线粒体交互作用在神经稳态调控中的作用及机制

The crosstalk between endoplasmic reticulum (ER) and mitochondria (Mito) is the fundamental subcellular responses for cell survival, but its role in secondary brain injury after TBI remains unknown. Our preliminary data showed that there was a dynamic change in the ER and Mito crosstalk in neural cell, and theses changes were correlated with unfolded protein response (UPR) after TBI. We hypothesized that the ER and Mito crosstalk could affect mitochondrial calcium and activate UPR different signaling pathways, by which it is involved in secondary brain injury. By labelling ER and Mito with markers transfected by lentivirus, the dynamic changes of ER and Mito crosstalk after TBI are detected in vitro and in vivo, by using the two-photon microscopy, subcellular separation and purification, immunofluorescence staining, and western-blot. These changes are further verified in human brain tissue. The role of ER and Mito crosstalk in secondary brain injury are further investigated by manipulating its crosstalk, knocking down functional protein. Finally, by investigating Mito calcium concentration, respiratory metabolism, oxidative stress and UPR signaling pathway, these could indicate its fundamental roles in the pathogenesis and regulation of neural homeostasis after TBI. These results could lay the ground work for novel therapeutic strategy for TBI treatment.

内质网（ER）和线粒体（Mt）交互作用是细胞存活的关键亚细胞反应，它与脑创伤（TBI）后继发性脑损害关系密切，但其机制尚不明确。我们预实验发现：TBI后神经细胞内两者交互反应呈现特征性变化并和未折叠蛋白反应（UPR）相关。因此有理由认为：两者交互反应可影响线粒体内Ca2+浓度并差异性激活UPR相关信号通路，导致继发性脑损害。本项目拟利用小鼠细胞、脑片和动物损伤模型，通过慢病毒转染荧光标记ER和Mt，利用双光子显微镜、亚细胞结构分离和纯化、免疫染色、蛋白定量等方法，动态观察两者交互反应变化；通过慢病毒转染改变ER和Mt交互反应、敲低内质网线粒体相关膜上关键功能蛋白，分别在细胞、组织及动物整体水平分析其参与继发脑损害的作用和途径；结合测定Mt内Ca2+浓度、呼吸代谢功能、氧化应激反应、UPR不同信号通路，明确其参与脑损害和调解神经稳态的分子机制和意义，为探索继发性脑损害干预新靶点提供实验依据。

内质网（ER）和线粒体（Mt）交互作用是细胞存活的关键亚细胞反应，但在脑外伤（TBI）后继发性脑损害中的作用及机制不明。本课题组在本项国家自然科学基金的资助下，利用细胞、脑组织和小鼠TBI损伤模型，通过慢病毒转染标记，亚细胞结构分离和纯化、免疫染色、蛋白定量等方法，初步探明了ER和Mt在TBI后神经稳态调控中的作用及可能机制，具体研究结果如下：（1）TBI后急性期神经细胞ER和Mt交互作用呈现动态变化，于伤后6小时达到高峰；（2）神经细胞ER和Mt交互作用的增强与线粒体氧化应激过度、内质网应激增强和未折叠蛋白反应过度以及NLRP1炎性小体介导的神经炎性反应的增强密切相关；（3）ER与Mt交互作用的增强还会导致Caspase12依赖的内质网应激介导的细胞凋亡反应；（4）通过沉默Pacs2表达而减少TBI后神经细胞ER和Mt的交互作用，可减少内质网钙离子向线粒体转移和线粒体钙超载，减轻内质网应激、UPR反应和NLRP1炎性小体介导的神经炎性反应，最终减轻血脑屏障的渗漏和内质网应激介导的细胞凋亡，并促进神经功能的恢复。上述实验结果已先后发表在：Brain Res.，Neural Regen Res.，Chin Med J., Front Cell Neurosci., Cell Mol Neurobiol.，和中华神经外科杂志上，并获国家实用新型专利2项。基于上述研究结果，课题负责人晋升主任医师，培养硕士研究生2名。