RTN3 在缺血性中风致脑白质轴突溃变的作用及其分子机制的研究

The mechanism of ischemic injury of brain after stroke is very complex. Recently, more study focus on the pathological process of white matter besides neuronal death. In the past, the studies on white matter mainly reported morphological collapse of axon, and the changes of glial cells(astrocytes, microglia) and associated protein (glial filament acidic protein, GFAP; myelin-associated glycoprotein, MAG; oligodendrocyte myelin glycoprotein, OMG). However, we still don’t know how axon, which is a main component of white matter and important structure of neuronal atransmission, is degenerated and how axonal transportation works in the injured brain after ischemic stroke attack. Therefore, in the present study, we propose to study the mechanism of RTN3, an player of axonal transporting protein, in the pathogenesis of axon-degeneration in the ischemic injured brain. We have known that RTN3 play important roles in cellular trafficking and neurite outgrowth as well as inhibition of A formation. However, oligo-RTN3 induce neurite dystrophy. We have reported that oxidative stress causes formation of RTN3 oligomers in the culture cells. Our preliminary study also indicated that RTN3 was reduced and HRTN3 was increased in rat brains after ischemic stroke. In the present project, we aimed to elucidate whether the change of RTN3 is involved in the pathogenesis of axonal degeneration and how RTN3 is participated in the process. We also would elucidate how oxidative stress induce the formation of HRTN3 and whether anti-oxidative stress could enhance RTN3 monomer level and enhance physiological function of RTN3 monomer, thereby protects axonal degeneration and toxicity. Therefore, we predict that the results of this study will be helpful for building the reconstruction of neural net works and beneficial for clinical investigation in the future.

卒中引起缺血性脑损伤机理十分复杂。近年来，人们在关注损伤脑内神经元胞体死亡机制的同时，也关注脑白质的病变。以往对脑白质损伤的研究主要集中在对神经突起周边细胞的形态及其相应骨架蛋白的表达， 而对参与轴突转运蛋白表达及其功能的变化尚缺乏证据。为此本项目提出研究神经细胞轴浆转运蛋白RTN3在缺血性脑损伤轴突退行性变中的作用及其病理意义。已经观察到单体RTN3参与轴突转运和信息传递，并具有抑制A生成，而聚合体HRTN3导致轴突溃变。我们离体研究发现氧化损伤参与HRTN3形成，初步观察到缺血脑内HRTN3增加，单体RTN3减少。本项目将采用大鼠脑缺血模型和离体细胞缺氧模型研究明确：1.该变化是否直接参与神经轴突的退行性病变呢; 2.该变化是否由氧化损伤所致； 3.抗氧化能否改善损伤脑内RTN3的病理反应。开展本项目的研究，对理解促进卒中患者脑内神经轴突病理变化具有重要意义。

原计划研究希望能确定神经轴突转运蛋白RTN3参与损伤脑内神经轴突的退行性病理作用及其机制。为此，我们采用大鼠实验性大脑中动脉栓塞制备缺血性脑卒中模型，利用高脂高糖饮食结合STZ注射建立糖尿病模型研究脑内神经元死亡和轴突溃变的现象和机制，结合离体细胞的模型开展分子和细胞机制研究。通过研究我们明确了缺血性脑卒中引起脑内再灌注损伤的病理过程中，通过氧化损伤以及激活炎症小体信号通路，诱导RTN3聚集，抑制轴浆转运功能，从而参与轴突的溃变。同时，激活的炎症小体又诱导细胞程序性坏死通路，促使缺血损伤神经元死亡。使用炎症抑制剂或者程序性细胞坏死信号通路抑制剂能减少神经元的溃变和死亡作用。本项目的研究发现，阐明了卒中脑内神经轴突病理变化的分子和细胞机制，为防治卒中患者的神经细胞死亡和退行病变的研发提供了新的靶点。本研究的部分相关工作已经发表，部分正在投稿过程中。已经发表论文（标注本基金）9篇，总影响因子41.529。申请专利1项。论文发表以来，被SCI引用76次，单篇引文最高31次。参加学术交流专题报告或大会报告13余次。通过项目的实施，培养毕业研究生获博士学位5人，获的硕士学位2人，其中1位毕业生获得上海市优秀博士生。