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

α-突触核蛋白（αS）在脑中的沉积是路易体痴呆（Lewy bodies dementia，LBD）的主要特征， 老年痴呆症是继阿尔茨海默病（AD）之后第二常见的痴呆症。尸体解剖和实验证据 表明LBD的进展可以由朊病毒样蛋白中的致病性αS（预形成的纤维，PFF）驱动。 这些αS聚集体表现出不同的菌株，这是α-突触核蛋白病异质性的基础。在我们 初步研究，我们已经扩增了患者的αS聚集体，并发现了帕金森氏症的菌株 具有认知障碍的疾病（PD-CI）与源自具有正常认知的PD（PD-CI）的那些不同。 NC）的横截面分析。对同一个体αS菌株的纵向研究进一步表明， 当认知从PD-NC进展到PD-CI时的应变转换。然而，有两个关键的知识 目前对αS菌株异质性的理解存在空白。首先，是否以及如何区分αS菌株 因为生物体大脑中不同的细胞反应知之甚少。我们的愿景是， 跨学科的努力是必不可少的，使新的见解对LBD的发病机制。我们建立 2 p显微镜下的长期活体单细胞跟踪平台，实现亚细胞分辨率成像 的位置，迁移，以及脑细胞的功能。使用此工具可以 我们可以通过获得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，包括暴露于不同αS菌株的神经元和小胶质细胞的时间反应。的 第二个关键的知识缺口是不同的αS菌株是否具有不同的细胞间繁殖动力学。 α-突触核蛋白病的金标准组织学方法是翻译后蛋白的免疫反应性。 αS在丝氨酸129（p129）处的磷酸化，排除了获得动态αS增殖的可能性 信息.为了解决这个问题，我们建议设计一种新的αS探针，称为NanoFAST，它具有 与其他αS聚集报告基因相比有一些固有的优点：（i）.检测未标记的αS聚集体;（ii）. 不需要在细胞中过表达αS以使报告基因起作用;以及（iii）.检测聚集或 αS的解聚（双向）过程。总的来说，我们组建了一个跨学科的团队， 神经科学，纳米体工程，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。如果我们成功的话，长期活体细胞跟踪的反应 神经元/小胶质细胞对不同αS菌株的反应将为研究其机制提供重要的见解。 痴呆相关αS菌株神经毒性的异质性NanoFAST可能会成为一种使能工具， 用于在基于细胞的测定中探索αS聚集和扩散动力学，甚至用于体内应用， 潜在的转化为临床早期诊断，进展评估或预后LBD，以打击 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.