Mechanisms of Neurodegeneration in Lewy Body Disorders

项目总结 阻止帕金森氏病(PD)等共核病的神经变性的一个主要障碍是 路易体痴呆是一种对脆弱细胞群体死亡原因缺乏了解的疾病。虽然 聚集的α-突触核蛋白路易病理发生在特定的神经元中，它们的功能障碍或 退行性变导致这些疾病的症状，路易氏病理本身如何发挥作用尚不清楚。近期 UNNI实验室的工作发现了一种以前未被认识到的蛋白质α-突触核蛋白的功能 用新发展的在体多光子成像技术修复核DNA双链断裂 研究小鼠体内α-突触核蛋白聚集的技术。这些方法现在已得到扩展(对于 第一次)研究活着的小鼠大脑中的DNA修复。突触核蛋白的意想不到的功能 提出了一个令人兴奋的新假说，即聚集的α-突触核蛋白路易包涵体在 神经退行性变。这一中心假设是，在疾病中，α-突触核蛋白被隔离在 胞质路易小体，降低其核DSB修复功能，导致路易小体细胞死亡。 含有神经元的。此外，还提出了最初导致刘易斯的纤维状α-突触核蛋白的来源 身体的形成来自于失调的DSB修复。初步数据表明，这一复杂情况 相互关系，与α-突触核蛋白聚集导致DSB修复失调，反之亦然。虽然 全新的，这种α-突触核蛋白和DSB修复之间的联系可以解释以前知之甚少的 DSB修复蛋白共济失调-毛细血管扩张症突变的人和小鼠之间的关联 和α-突触核蛋白聚集，以及特定突触核蛋白家族成员与癌症之间的关系(例如，α-突触核蛋白聚集性)。 突触核蛋白与黑色素瘤、γ-突触核蛋白与乳腺癌)。这项提议将结合使用先进的 纯化的、体外重组的系统、小鼠脑活体以及小鼠和人的成像方法 (PD，DLB)固定组织，以测试α-突触核蛋白如何介导DSB修复(目标1)，如何丢失核α- 胞质路易包涵体形成后的突触核蛋白功能失调调节DSB修复并参与 神经细胞死亡(目标2)，以及DSB修复失调如何导致路易包涵体形成(目标3)。 总体而言，这个项目是创新的，因为它使用了强大的、新的活体实验方法来测试 关于α-突触核蛋白聚集如何与路易氏病理相关的全新假说 神经退行性变。这一贡献将是重大的，因为它将提供一套全新的目标 用于治疗这些专注于DSB修复途径的衰弱神经退行性疾病，以及 因为详细了解α-突触核蛋白介导的DSB修复将增加我们的基础科学 了解这一重要的生物过程。

PROJECT SUMMARY One major obstacle to halting neurodegeneration in synucleinopathies like Parkinson's Disease (PD) and Dementia with Lewy Bodies (DLB) is a lack of understanding of why vulnerable cell populations die. Although aggregated alpha-synuclein Lewy pathology occurs within specific neurons, and their dysfunction or degeneration leads to symptoms in these diseases, how Lewy pathology itself plays a role is unclear. Recent work by the Unni lab has discovered a previously unrecognized function for the protein alpha-synuclein in repairing nuclear DNA double-strand breaks (DSB), by using newly developed in vivo multiphoton imaging techniques to study alpha-synuclein aggregation in mice. These approaches have now been extended (for the first time) to study DNA repair in living mouse brain. The unexpected function for alpha-synuclein immediately suggests an exciting new hypothesis for the role of aggregated alpha-synuclein Lewy inclusions in neurodegeneration. This central hypothesis is that in disease, alpha-synuclein protein is sequestered in cytoplasmic Lewy bodies, decreasing its nuclear DSB repair function and leading to cell death of Lewy body- containing neurons. Furthermore, it is proposed that the source of fibrillar α-synuclein that initially seeds Lewy body formation comes from dysregulated DSB repair. The preliminary data suggest this complex interrelationship, with alpha-synuclein aggregation causing dysregulated DSB repair and vice versa. Although completely novel, this link between alpha-synuclein and DSB repair could explain previously poorly understood associations between human and mouse mutations in the DSB repair protein Ataxia-Telangiectasia Mutated and alpha-synuclein aggregation, and between specific synuclein family members and cancer (e.g. alpha- synuclein & melanoma, gamma-synuclein & breast cancer). This proposal will use a combination of advanced imaging approaches in purified, reconstituted in vitro systems, in mouse brain in vivo, and in mouse & human (PD, DLB) fixed tissue to test how alpha-synuclein mediates DSB repair (Aim 1), how loss of nuclear α- synuclein function after cytoplasmic Lewy inclusion formation dysregulates DSB repair and contributes to neuronal cell death (Aim 2), and how dysregulated DSB repair can lead to Lewy inclusion formation (Aim 3). Overall, this project is innovative because it uses powerful, new in vivo experimental approaches to test a fundamentally new hypothesis for how alpha-synuclein aggregation into Lewy pathology is related to neurodegeneration. This contribution will be significant because it will provide a completely new set of targets for treating these debilitating neurodegenerative disorders that focuses on the DSB repair pathway, and because understanding alpha-synuclein-mediated DSB repair in detail will increase our basic science knowledge of this important biological process.