Structural Biology of Alpha-Synuclein in Lewy Body Dementia

摘要 帕金森病（PD）在病理学上被定义为α-突触核蛋白（Asyn）原纤维在帕金森病（PD）中的积累。 神经元胞质和神经炎包涵体，称为路易体和路易神经突。Asyn的角色 PD的发病机制得到了编码Asyn的基因中显性突变的鉴定的支持， （SNCA）在罕见的PD家族性版本中。PD常发生痴呆。它有时开始于 与运动症状（通常称为路易体痴呆或DLB）大致相同的时间，或 运动症状开始后长达20年（PD伴痴呆或PDD）。路易体痴呆（Lewy Body Dementia，LBD） 包括这一系列的临床表现，并与广泛沉积的阿辛 遍布大脑尤其是新皮层的纤维靶向Asyn的多种治疗方法 正在进行积累。另一个优先事项是开发正电子发射断层扫描（PET） 成像剂，以量化活体个体中Asyn的沉积，作为靶点接合的生物标志物， 疾病进展。了解LBD中的Asyn纤维结构可以指导Asyn靶向药物的开发， 治疗和成像剂。在这个项目中，我们将使用固态核磁共振（SSNMR）和低温核磁共振的组合， 电子显微镜（cryo-EM）以确定LBD中Asyn原纤维的原子分辨率结构。我们开发 从组织中分离原纤维并使其在标记的 单体Asyn蛋白的SSNMR和cryo-EM研究，使更全面的分析结构。 我们将分析和比较从LBD尸检病例的多个亚组中分离的Asyn纤维的结构 根据早期与晚期痴呆发作以及是否存在共同发生的淀粉样蛋白β来定义 积累，并确定结构变异是否与疾病表型有关。推进 这些结构研究的翻译，我们将利用SSNMR和cryo-EM来确定的结构特征 主要PET成像配体候选物的结合位点，其可以指导PET配体的进一步优化。 最后，我们将利用来源于LBD组织的Asyn原纤维在细胞培养物中进行Asyn原纤维的种子积累 和小鼠模型。我们将利用固体核磁共振、冷冻电镜和冷冻电子断层扫描来分析Asyn原纤维 这些模型系统中的结构，这将指导未来的疾病机制，PET配体 发展和治疗发展。

Abstract Parkinson disease (PD) is defined pathologically by the accumulation of alpha-synuclein (Asyn) fibrils in neuronal cytoplasmic and neuritic inclusions known as Lewy bodies and Lewy neurites. The role of Asyn in the pathogenesis of PD is supported by the identification of dominant mutations in the gene encoding Asyn (SNCA) in rare familial versions of PD. Dementia occurs frequently in PD. It sometimes begins at approximately the same time as motor symptoms (often referred to as Dementia with Lewy bodies or DLB), or up to 20 years after motor symptoms begin (PD with dementia or PDD). The term Lewy body dementia (LBD) encompasses this spectrum of clinical presentations and is associated with widespread deposition of Asyn fibrils throughout the brain, particularly neocortex. Multiple therapeutic approaches targeting Asyn accumulation are being pursued. A further priority is to develop a Positron Emission Tomography (PET) imaging agent to quantify the deposition of Asyn in living individuals, as a biomarker for target engagement and disease progression. Understanding Asyn fibril structure in LBD can guide the development of Asyn-targeted therapies and imaging agents. In this project, we will use a combination of solid-state NMR (SSNMR) and cryo- electron microscopy (cryo-EM) to determine atomic resolution structures of Asyn fibrils in LBD. We developed multiple complimentary approaches to isolate fibrils from tissue and grow them in the presence of labeled monomeric Asyn protein for SSNMR and cryo-EM studies, enabling more comprehensive analysis of structure. We will analyze and compare structures of Asyn fibrils isolated from multiple subgroups of LBD autopsy cases defined by early versus late onset of dementia, as well as the presence or absence of co-occurring amyloid β accumulation, and determine whether structural variations relate to disease phenotype. To promote the translation of these structural studies we will utilize SSNMR and cryo-EM to determine the structural features of binding sites for leading PET imaging ligand candidates, which can guide further optimization of PET ligands. Finally, we will utilize Asyn fibrils derived from LBD tissue to seed accumulation of Asyn fibrils in cell culture and mouse models. We will utilize SSNMR, cryo-EM and cryo-electron tomography to analyze Asyn fibril structure in these model systems, which will guide future studies of disease mechanisms, PET ligand development and therapeutic development.