Administrative supplement to Regulation of mitochondrial DNA homeostasis and neuroinflammation by Fascin

项目摘要/摘要 阿尔茨海默病(AD)是最常见的神经退行性疾病，每十个年龄段的人中就有一个受到影响 65岁及以上。由于对AD发病机制的了解有限，目前尚无有效的治疗方法 对这种毁灭性疾病的治疗。此应用程序的目标是调查一个意外的角色 肌动蛋白结合蛋白Fasin在调节线粒体DNA(MtDNA)稳态、氧化中的作用 磷酸化(OXPHOS)、线粒体氧化应激、神经炎症和神经变性，AS 以及这些过程的失调如何在AD的发病机制中起作用。筋膜蛋白是一种肌动蛋白捆绑 肌动蛋白细丝交叉连接成紧密而坚硬的束所必需的蛋白质。当前的范式 认为筋膜蛋白通过产生突起的膜结构促进细胞迁移和肿瘤侵袭 例如丝状伪足。我们最近有了一个令人惊讶的发现，筋膜蛋白的缺失会破坏线粒体的F- 肌动蛋白捆绑，进而导致线粒体呼吸复合体生物发生异常和受损 线粒体OXPHOS，提示了Fasin在线粒体功能调节中的一个新的作用。 从机制上讲，筋膜蛋白耗竭细胞的线粒体功能障碍是由于mtDNA增加所致。 聚集和渗漏。鉴于线粒体DNA可以强烈地诱导炎症体激活和炎症 细胞因子表达、筋膜蛋白缺乏可能在引起神经炎症中起到意想不到的作用。 重要的是，我们发现束蛋白在大脑中被切割成37 kDa的功能显性-负性形式 阿尔茨海默病患者和AD小鼠模型。病毒介导的Fasin在AD小鼠海马区的表达 减轻疾病症状。此外，我们培育的Fascin基因敲除小鼠表现出了 线粒体缺陷和大脑中神经元的显著丧失。根据这些初步数据，我们 假设束蛋白控制着大脑中线粒体的功能和线粒体DNA的稳态。束 阿尔茨海默病的功能缺陷导致严重的线粒体缺陷，神经炎症和 神经退行性变。为了检验这一假设，在目标1中，我们将定义筋膜蛋白在调节中的作用 小鼠脑内线粒体功能、线粒体DNA稳态、神经炎症和神经细胞死亡 在活体内。在目标2中，我们将研究由蛋白水解性切割引起的筋膜蛋白功能缺陷。 用AD患者脑组织和小鼠模型研究AD的发病过程 筋膜蛋白功能缺陷导致线粒体DNA泄漏、氧化应激、 神经炎症和变性。在目标3中，我们将研究Fasin转基因表达的影响 减轻小鼠阿尔茨海默病的病理表型和疾病症状。圆满完成 拟议的研究将揭示发束素在调节线粒体功能、线粒体DNA动态平衡、 神经炎症和神经变性。研究AD患者的筋膜蛋白功能缺陷将有所帮助 了解疾病的致病机制，促进治疗的发展。

Project Summary/Abstract Alzheimer’s disease (AD), the most common neurodegenerative disorder, affects one in ten people age 65 and older. Due to limited understanding of mechanisms underlying AD pathogenesis, there is no effective treatment for this devastating disease. The goal of this application is to investigate an unexpected role for actin bundling protein Fascin in regulating mitochondrial nucleoid DNA (mtDNA) homeostasis, oxidative phosphorylation (OXPHOS), mitochondrial oxidative stress, neuroinflammation, and neurodegeneration, as well as how dysregulation of these processes contributes to AD pathogenesis. Fascin is an actin bundling protein essential for the cross-linking of actin filaments into compact and rigid bundles. The current paradigm posits that Fascin promotes cell migration and tumor invasion by generating protrusive membrane structures such as filopodia. We recently made the surprising finding that depletion of Fascin disrupts mitochondrial F- actin bundling, which in turn causes abnormal mitochondrial respiratory complex biogenesis and impaired mitochondrial OXPHOS, suggesting a novel role of Fascin in the regulation of mitochondrial function. Mechanistically the mitochondrial dysfunction in Fascin depleted cells was due to increased mtDNA aggregation and leakage. Given that mtDNA can robustly induce inflammasome activation and inflammatory cytokine expression, Fascin deficiency may play an unexpected role in causing neuroinflammation. Importantly, we found that Fascin is cleaved into a 37kDa functionally dominant-negative form in the brains of AD patients and AD mouse models. Virus-mediated expression of Fascin in AD mouse hippocampus mitigated disease symptoms. In addition, Fascin knockout mice we generated showed profound mitochondrial defects and significant loss of neurons in the brain. Based on these preliminary data, we hypothesize that Fascin controls mitochondrial function and mtDNA homeostasis in the brain. Fascin functional deficiency in AD leads to significant mitochondrial defects, neuroinflammation and neurodegeneration. To test the hypothesis, in Aim 1 we will define the role of Fascin in regulating mitochondrial function, mtDNA homeostasis, neuroinflammation and neuronal cell death in the mouse brain in vivo. In Aim 2 we will investigate the functional deficiency of Fascin caused by proteolytic cleavage during the course of AD pathogenesis using brain tissues from AD patients and mouse models, and to elucidate mechanisms underlying how Fascin functional deficiency causes mtDNA leakage, oxidative stress, neuroinflammation, and degeneration. In Aim 3 we will study the effects of transgenic expression of Fascin on alleviating AD pathological phenotypes and disease symptoms in mice. Successful completion of the proposed studies will reveal Fascin’s novel role in regulating mitochondrial function, mtDNA homeostasis, neuroinflammation and neurodegeneration. Investigating Fascin functional deficiency in AD will help understand disease pathogenic mechanisms and facilitate therapeutic development.