Role of alpha Synuclein and microRNA 7a in post stroke brain damage

 描述(由申请人提供)： 中风(局灶性脑缺血)是老年退伍军人死亡和残疾的主要原因。此外，许多老年退伍军人还患有神经退行性疾病。卒中后继发性脑损伤和神经功能障碍的机制尚不完全清楚。对这一提议的初步研究显示，在局灶性脑缺血的啮齿动物的大脑中诱导了α-突触核蛋白的表达。由于α-突触核蛋白被认为是帕金森病和其他慢性神经退行性疾病中神经元死亡的主要原因，目前的提议将检验“a-突触核蛋白是中风后脑损伤的一个因素”的假说。这一假说将通过以下特定目的来检验：目的1是使用α-突触核蛋白siRNA介导的基因敲除和α-突触核蛋白基因敲除小鼠作为替代方法，评估a-突触核蛋白在促进实验性卒中后继发性脑损伤和神经功能障碍中的功能意义。目的2是评估microRNA miR-7a的下调是否与脑缺血后α-突触核蛋白的诱导有关。我们将测试用miR模拟物恢复miR-7a水平是否能减少α-突触核蛋白介导的缺血后继发性脑损伤和神经功能障碍。目的3是确定卒中后诱导的α-突触核蛋白是否通过调节炎症、氧化应激、细胞凋亡、线粒体分裂和自噬而介导继发性脑损伤。我们将测试α-突触核蛋白基因敲除是否能抑制这些缺血后的病理生理机制，从而减少缺血后的脑损伤。目的4是测试a-突触核蛋白的翻译后修饰在缺血性脑损伤中的作用。我们将具体研究被认为促进α-突触核蛋白齐聚和毒性的Ser-129磷酸化，以及被认为对溶酶体降解a-突触核蛋白起重要作用的赖氨酸泛素化。目的5是研究卒中后α-突触核蛋白诱导的长期意义。这一点很重要，因为在慢性神经退行性疾病中，α-突触核蛋白的积累和毒性会持续数十年；而a-突触核蛋白在中风后几个小时内迅速增加。总体而言，本项目将作为一座桥梁，了解a-突触核蛋白的作用，并设计基于a-突触核蛋白和miRNA-7a的新疗法，将退伍军人中风后的脑损伤降至最低。拟议工作与退伍军人管理局患者护理任务的相关性：每年有7,000名退伍军人患上新的中风，有80,000名幸存的退伍军人患有中风引起的神经功能障碍。除非破译中风后脑损伤的分子机制，并根据新的靶点开发治疗方法，否则这种毁灭性疾病对退伍军人的负面影响在不久的将来会极大地增加。A-突触核蛋白是减少中风后脑损伤的一个有吸引力的靶点，因为正在进行的帕金森病研究已经提供了许多资源。成功完成评估中风后α-突触核蛋白重要性的拟议研究有助于退伍军人中幸存的中风患者的康复。

 DESCRIPTION (provided by applicant): Stroke (focal cerebral ischemia) is a leading cause of death and disability in aging Veterans. Furthermore, many aged Veterans also suffer from neurodegenerative disorders. The mechanisms that contribute to secondary brain damage and neurological dysfunction after stroke are not completely understood. Preliminary studies of this proposal show induction of a-Synuclein expression in the brains of rodents subjected to focal ischemia. As a-Synuclein is thought to be a major contributor of neuronal death in Parkinson Disease and other chronic neurodegenerative diseases, the present proposal will test the hypothesis "a-Synuclein is a contributor of post-stroke brain damage." This hypothesis will be tested by the following Specific Aims: Aim 1 is to evaluate the functional significance of a-Synuclein in promoting secondary brain damage and neurological dysfunction following experimental stroke using a-Synuclein siRNA-mediated knockdown and a-Synuclein knockout mice as alternate approaches. Aim 2 is to evaluate if down-regulation of microRNA miR-7a is responsible for a-Synuclein protein induction in the post-ischemic brain. We will test if restoring miR-7a levels with a miR mimic curtails a- synuclein mediated post-ischemic secondary brain damage and neurological dysfunction. Aim 3 is to identify if a-Synuclein induced after stroke mediates secondary brain damage by modulating inflammation, oxidative stress, apoptosis, mitochondrial fission, and autophagy. We will test if a- Synuclein knockdown curtails these post-ischemic pathophysiological mechanisms and thus decreases post-ischemic brain damage. Aim 4 is to test the role of post-translational modifications of a-Synuclein in ischemic brain damage. We will specifically study ser-129 phosphorylation which is thought to promote a-Synuclein oligomerization and toxicity and lysine ubiquitination which is thought to be important for a-Synuclein degradation by lysosomes. Aim 5 is to study the long-term implications of a-Synuclein induction after stroke. This is important as a- Synuclein accumulation and toxicity occur over decades in chronic neurodegenerative conditions; whereas a-Synuclein increases rapidly within hours after stroke. Overall, the present project will serve as a bridge to understan the role of a-Synuclein and to design novel therapies based on a-Synuclein and miRNA-7a to minimize the post-stroke brain damage in Veterans. Relevance of the proposed work to the VA patient care mission: Every year, >7,000 Veterans suffer new strokes and there are >80,000 surviving Veterans with stroke-induced neurological dysfunction. The negative impact of this devastating disease on Veterans increases enormously in the near future unless the molecular mechanisms of post-stroke brain damage are deciphered and therapies are developed based on the new targets. a-Synuclein is an attractive target to curtail post-stroke brain damage as many resources are already available from the ongoing research on Parkinson Disease. Successful completion of the proposed studies to evaluate the significance of a-Synuclein after stroke helps the recovery of surviving stroke sufferers among Veterans.