Shedding light on functional heterogeneity of dementia-related alpha-synuclein strains

α-突触核蛋白在脑内的沉积(αS)是路易体痴呆的一个主要特征。 仅次于阿尔茨海默病(AD)的第二大常见痴呆症。尸检和实验证据 研究表明，致病的αS(预制纤维)可以在类普里子中驱动腰椎间盘突出症的进展 时尚，这些αS聚合体显示了α-突触核病症异质性下的不同菌株。在我们的 初步研究，我们从患者身上扩增了S的α聚合体，发现了帕金森氏症的菌株 认知障碍疾病(PD-CI)不同于认知正常的帕金森病(PD-CI) NC)在横截面分析中。对同一个体的αS毒株的纵向研究进一步表明 当认知从PD-NC向PD-CI发展时的应变转换。然而，有两个关键知识 目前对αS毒株异质性的认识存在空白。首先，S的α菌株是否以及如何区分 导致活着的有机体大脑中不同的细胞反应鲜为人知。我们的愿景是 跨学科的努力对于LBD的发病机制带来新的见解是必不可少的。我们已经确立了 2P显微镜下的长期活体内单细胞跟踪平台，实现亚细胞分辨率成像 对活体小鼠的脑细胞的位置、迁移和功能进行了几周的研究。实施此工具可以 美国将通过获取脑细胞如何响应的动态图像来解决上述问题 αS随时间的变化，包括神经元和小胶质细胞对不同菌株αS的时间反应。 第二个关键的知识缺口是不同的αS毒株是否具有不同的细胞间繁殖动力学。 α-突触核病的金标准组织学方法是翻译后免疫反应性 αS丝氨酸129(P129)的磷酸化，排除了获得动态αS繁殖的可能性 信息。为了解决这个问题，我们建议为αS设计一种新型的探针，称为NanoFAST，它已经 相对于其他αS聚合记者的几个固有优势：(一)未标记的αS聚合体的检测； 不需要在细胞中过度表达αS，记者可以工作；以及(Iii)。能够检测聚合或 αS的分解(双向)过程。总的来说，我们已经组建了一个跨学科的团队，涵盖 神经科学，纳米身体工程，生物物理学和临床实践，以解决关键的知识差距 对αS异质性的理解。如果我们成功了，长期的活体细胞追踪反应 神经元/小胶质细胞对不同αS株的作用将为揭示其致病机制提供重要依据 痴呆相关αS菌株神经毒性的异质性。NanoFAST可能成为一种使能工具 为了探索αS在基于细胞的分析中的聚集和传播动力学，甚至用于体内应用， LBD的早期诊断、进展评估或预后可转化为临床的潜力 这些毁灭性的神经退行性疾病。

The deposition of α-synuclein (αS) in the brain is a main feature of Lewy bodies dementia (LBD), which is the 2nd most common dementia after Alzheimer’s disease (AD). Both postmortem and experimental evidence showed that the progression of LBD can be driven by pathogenic αS (preformed fibrils, PFF) in a prion-like fashion, and these αS aggregates exhibit distinct strains underling heterogeneity of α-synucleinopathies. In our preliminary studies, we have amplified αS aggregates from patients and found the strains from Parkinson's disease with cognitive impairment (PD-CI) are distinct from those derived from PD with normal cognition (PD- NC) in the cross-sectional analysis. Longitudinal studies of αS strains from the same individuals further indicate a strain conversion when cognition progresses from PD-NC to PD-CI. However, there are two critical knowledge gaps in the current understanding of the heterogeneity of αS strains. First, whether and how distinct αS strains cause different cellular responses in the brain of a living organism are poorly known. It is our vision that interdisciplinary efforts are essential to bring novel insights on the pathogenesis of LBD. We have established the long-term intravital single-cell tracking platform under 2p microscopy, enabling subcellular-resolution imaging of the location, migration, and function of brain cells in live mice for a few weeks. Implementing this tool allows us to address the above-mentioned question by obtaining a dynamic picture about how brain cells respond to αS over time, including temporal responses from neurons and microglia exposed to different strains of αS. The second critical knowledge gap is whether different strains of αS have distinct cell-to-cell propagation dynamics. The gold standard histological methodology for α-synucleinopathies is the immunoreactivity of posttranslational phosphorylation of αS at serine 129 (p129), precluding the possibility to obtain dynamic αS propagation information. To address this issue, we propose to design a novel probe for αS, called the NanoFAST, which has a few inherent advantages over other αS aggregation reporters: (i). detection of untagged αS aggregates; (ii). no need to overexpress αS in cells for the reporter to work; and (iii). the ability to detect either aggregation or disaggregation (bi-directional) process of αS. Overall, we have assembled an interdisciplinary team covering neuroscience, nanobody engineering, biophysics, and clinical practice to address the critical knowledge gaps in the understanding of αS heterogeneity. If we are successful, the long-term intravital cell tracking of the response of neurons/microglia to different αS strains will provide important insights on the mechanism underlying heterogeneity in neurotoxicity from dementia-related αS strains. The NanoFAST may become an enabling tool for exploring αS aggregating and spreading dynamics in cell-based assay or even for in vivo applications, with the potential to be translated to clinic for early diagnosis, progression evaluation or prognosis of LBD to combat these devastating neurodegenerative diseases.