MiR-137-3p在撕脱伤运动神经元凋亡中的作用和机制

项目名称： MiR-137-3p在撕脱伤运动神经元凋亡中的作用和机制

项目编号： No.31471030

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 神经、认识与心理学

项目作者： 周丽华

作者单位： 中山大学

项目金额： 87万元

中文摘要： 神经根撕脱伤导致运动神经元凋亡的机制不明，因此临床无法完全修复患者的运动功能。前期研究我们证实：创伤导致运动神经元内nNOS基因在转录后表达水平的改变是不可逆凋亡的关键，但不明了调控nNOS基因的机制。近期我们发现撕脱伤后脊髓miR-137-3p显著上调，其靶基因Calpain2蛋白显著下调。鉴于Calpain2能通过降解NOS蛋白下调nNOS基因并与Caspase-3的激活相关；本项目提出:miR-137-3p↑→Calpain2↓→nNOS和iNOS积聚→NO过量→过氧化;Caspase-3激活→运动神经元凋亡的假说；并拟构建慢病毒载体转染撕脱伤大鼠脊髓，同时建立miR-137-3p海绵转基因小鼠，通过上调和下调脊髓miR-137-3p基因水平，比较调控前后运动神经元内上述各基因的表达变化，定量创伤运动神经元的凋亡程度，最终确定miR-137-3p是能阻止运动神经元凋亡的关键分子。

中文关键词： miR-137-3p；运动神经元；细胞凋亡；神经元型一氧化氮合酶；成年大鼠

英文摘要： Spinal roots avulsion is a kind of trauma which induces motor functional loss because of the spinal motoneuron apoptosis. Up to now, we can not repair the hand movement in clinic even with a sucessful surgery to rebuild the connection between the spinal cord and the target muscles. The reason is because the regenerative velocity of the motor nerves is slower compared to the distance of the spianl motoneurons and the intrinsic hand muscles. So, it is necessary to explore the mechanism of avulsion-induced motoneurons apoptosis so that we can inhibit the velocity of the motoneurons apoptosis, meanwhile to enhance the regenerative capacity of the spinal motoneurons after surgery. We have focused on mechanism of motoneurons apoptosis for 15 years. We have proved that the avulsion-induced nNOS protein expressions in adult spianl motoneurons represent the beginnning of motoneurons apoptosis instead of regeneration. However, downregulate the nNOS mRNAs in the spianl cord could not stop but accelerate the avulsion-induced motoneurons apoptosis. It suggestes that the nNOS gene was manupulated posttranslationally after avulsion injury. During the recent 3 years, we have studied microRNAs expression patterns in the spinal cord after roots avulsion. We prvoed that miR-137-3p is obviously upregulated and it's targets gene, Calpain2 is downregulated inside injured motoneurons. Since Calpain2 acts on cleavage of NOS proteins, and both nNOS protein inside motoneurons and iNOS protein inside glial cells have been proved to upregulated during the apoptosis of injured motoneurons, we therefore hypothesis the mechanism of avulsion-induced motoneurons apoptosis is the miR-137-3p upregulation-Calpain2 downregulation-nNOS, iNOS upregulation; and NO overdose in the injured spinal cord-oxidative stress. In the present study, we will construct the lentivirus vectors with miR-137-3p or with miR-137-3p sponges; we also wants to construct the miR-137-3p sponges transgene mice. The lentivirus vectors will be tranfused to the spinal cord and the motoneurons after brachial roots avulsion of the adult rats. After the knock-in and knock-down of the miR-137-3p genes in injured spianl cords, we will study whether these method can save or accelarates avulsion-induced motoneruons apoptosis, and whether manupulation of the miR-137-3p genes will block the Calapin2/nNOS,iNOS/NO; Caspase-3/oxidative stress pathway. Finally we will answer the question that whether miR-137-3p can be used as a molecular taget for the treatment of motoneurons diseases.

英文关键词： miR-137-3p;motoneurons;apoptosis;neuronal nitric oxide synthase;adult rat