Initiation and propagation of alpha synuclein oligomers--Relevance for Parkinson s disease

帕金森病（PD）的发病机制以α突触核蛋白（asyn）的启动和增殖为特征。最近的证据表明，某些形式的失联蛋白由神经元分泌并被邻近的神经元吸收，从而表明细胞外失联蛋白可能对帕金森病有毒性。本提案的总体目标是基于三条调查线来研究PD病理发生和传播的潜在机制。第一种方法将在蛋白质水平上研究异构体病理的起始和繁殖过程。在这里，我们将研究异构体低聚物在体外和体内的细胞间传播。为此，我们建立了一种基于分裂蛋白互补实验的创新动物模型，该模型允许在体内以高度敏感的方式测量异构体。在我们最初的实验中，我们发现在细胞培养中，异构体可以在细胞外空间形成有毒的低聚物，这些低聚物与外泌体或游离体一起释放。我们还发现这些低聚物可以被神经元吸收，并作为额外低聚物形成的中心。我们现在将确定病理相关的异构体物种负责在体外和体内繁殖。我们将在体内研究异构体寡聚物通过外泌体和游离异构体在神经元之间的朊病毒样传播。在第二项研究中，我们将探索异构体低聚物向非神经元细胞的传递，更准确地说是免疫细胞。我们之前在PD患者的外周血中发现了过度活跃的单核细胞，但asyn在单核细胞活化中的作用尚不清楚。因此，我们建议研究不同形式的异构体在单核细胞活化中的作用。我们推测，自由形式或与外泌体相关的不同细胞外异构体可能是PD患者血液中单核细胞刺激和/或预处理的有效触发因素。由于asyn可能不是唯一负责疾病病理传播的传递分子底物，我们将在第三条研究中验证病理传播也部分由非蛋白物种组成的假设，例如编码或非编码RNA分子。因此，我们将探索与外泌体相关的编码或非编码RNA分子是否有助于邻近细胞的重编程。在这个项目中，我们将采用互补的方法来阐明asynn病理发生和传播的基本机制。如果这个研究项目成功，它将直接影响帕金森病的临床诊断，并将为帕金森病和其他神经退行性疾病的独特治疗干预开辟新的途径。

Parkinsons disease (PD) pathogenesis is characterized by initiation and propagation of alpha synuclein (asyn) pathology. Recent evidence suggests that some forms of asyn are secreted from neurons and taken up by neighboring neurons, thereby suggesting that extracellular asyn species might be toxic in PD. The overall goal of this proposal is to study the underlying mechanism of initiation and propagation of PD pathology based on three lines of investigation. The first approach will study initiation and propagation processes of asyn pathology on the protein level. Here we will investigate cell-to-cell- transmission of asyn oligomers in vitro and in vivo. For this purpose we have generated an innovative animal model based on a split protein complementation assay that allows measurement of asyn oligomers in a highly sensitive way in vivo. In our initial experiments, we found in cell culture that asyn species can form toxic oligomeric species in the extracellular space which are released in association with exosomes or free. We also found that these oligomeric species can be taken up by neurons and act as a nidus for additional oligomer formation. We will now identify the pathologically relevant asyn species responsible for propagation in vitro and in vivo. We will investigate the prion-like transmission of asyn oligomers from neuron to neuron via exosomes and free asyn in vivo. In the second line of investigation we will explore the transmission of asyn oligomers to non-neuronal cells more precisely immune cells. We previously found hyperactive monocytes in the peripheral blood of PD patients but the role of asyn in monocytes activation is not clear yet. We therefore propose to investigate the role of different asyn forms in monocyte activation. We speculate that different extracellular asyn species in free form or associated with exosomes might be an effective trigger for stimulation and/or pre-conditioning of monocytes in the blood of PD patients. As asyn may not be the only transmitting molecular substrate responsible for spreading of disease pathology, we will test in the third line of investigation the hypothesis that transmission of pathology also partially consist of a non-proteinaccious species, e.g. coding or non-coding RNA molecules. We will therefore explore whether coding or non-coding RNA molecules associated to exosomes or free contribute to reprogramming of neighboring cells. Together, in this project we will implement complementary approaches to elucidate the fundamental mechanisms of initiation and propagation of asyn pathology. If this research program will be successful it will directly impact clinical diagnostics in PD and will open new avenues for unique therapeutic interventions for PD and other neurodegenerative diseases.