创伤性脑损伤后microRNA-124通过REST/CoREST调节神经元轴突再生的作用与机制研究

Neuronal axonal injury is a main cause of disability following traumatic brain injury(TBI). Promoting the regeneration of injured axons is still a tough problem in neuroscientific research. The miR-124 which is specificly and abundantly expressed in neurons, through its target genes REST/CoREST, not only determines the differentiation of neural stem cells into neurons, but also induces a neuronal gene profile in no-neuronal cells. The latest research indicated that miR-124 regulated and controled the axonal navigation and growth of retinal ganglion cell as a way of "molecular clock". Our preliminary work showed that the expression of miR-124 was down-regulated after TBI, suggesting that miR-124 might take a crucial role in post-traumatic axonal growth and path-finding. The present project, based on the well-established transgenic miR-124 mice, is aimed at analyzing the change of miR-124 and its relevance with axonal regeneration, uncovering the inner relation between miR-124 and the expression of Nrp-1 (axon guidance cue receptor) after TBI, investigating the molecular mechanism of miR-124 in regulating axonal growth and navigation, and trying to intervening the expression of miR-124 to promote axonal regeneration following TBI. This project might provide a new breakthrough in the research on mechanism and therapy of TBI.

神经元轴突损伤是TBI致残的重要原因。促进TBI后神经元轴突的再生是神经科学研究的难点。miR-124是神经元特异高表达的miRNA，可通过其靶基因REST/CoREST，不仅能决定神经干细胞向神经元的分化，而且还能使miR-124转染的非神经元细胞出现类似神经元的基因表型；最新研究显示：miR-124还能以"分子时钟"的方式，精确调控视网膜神经节细胞轴突的生长和发育。我们研究发现：TBI后miR-124表达下调，提示：miR-124可能在TBI后神经元轴突生长和致靶中发挥重要作用。本课题在成功建立miR-124转基因小鼠的基础上，分析TBI后miR-124的变化及其与神经元轴突再生的关系，揭示miR-124与轴突导向因子受体Nrp-1的内在联系，研究miR-124调节轴突生长与致靶的分子机制，尝试干预miR-124促进TBI后轴突再生与修复，将可能为TBI损伤机制与救治研究带来新突破。

创伤性颅脑损伤（traumatic brain injury， TBI）在平战时见常，致死率和致残率极高。神经元轴突损伤是TBI致残的重要原因，促进TBI后神经元轴突的再生是神经科学研究的难点。miR-124是神经元特异性高表达的miRNA，不仅能决定神经干细胞向神经元的分化，而且还能使miR-124转染的非神经元细胞出现类似神经元的基因表型。本课题按照原计划进展顺利：（1）在建立了稳定的小鼠TBI模型和神经元体外损伤模型基础上，利用原位杂交、qRT-PCR及免疫荧光染色等方法，探讨TBI后miR-124的表达变化及其与神经元轴突再生的关系。（2）利用活细胞工作、Western blot和免疫组化等手段，在组织形态学、蛋白学和核酸水平证实了TBI后miR-124表达变化对神经元再生、凋亡以及轴突再生的影响。(3)利用免疫共沉淀、转基因干涉技术、荧光素酶基因报告实验和生物信息学数据库等方法，研究了TBI后miR-124通过REST/CoREST调控神经元轴突再生的作用机制。本研究为TBI后通过外泌体导入microRNA调控颅内微环境修复神经功能缺失提供了理论依据和研究基础。