Mechanisms of Mutant Prion Protein Aggregation Within Endolysosomal Pathways

对朊病毒病患者大脑的超微结构研究显示， 内溶酶体内营养不良的神经突内错误折叠的PrP。其他复杂的结构， 存在于这些营养不良中并且现在被认为是朊病毒病理学的共同特征， 包括自噬性空泡样膜结合细胞器、溶酶体电子致密细胞器、 体和增大的内溶酶体。导致这些形成的机制 结构仍然未知。我们的研究已经确定了哺乳动物的内溶酶体途径 我们称之为轴突快速内体分选和运输依赖性聚集的神经元 （ARESTA），其驱动错误折叠的突变型朊病毒的神经毒性轴突聚集体的形成 蛋白质（PrP）内的内膜结构，我们称之为“endoggresome”。远景目标 这一建议的一个特点是内吞途径发挥作用的病理生理学 朊病毒疾病，阿尔茨海默病，以及阿尔茨海默病相关的痴呆症， 为药物治疗提供可操作的靶点。这项建议的目的是 (i)确定ARESTA通路在轴突内分泌体形成中的一般性 表达各种家族性PrP突变的神经元，并表征其分子和 神经毒性内分泌体的超微结构架构;（ii）确定 突变型PrP内分泌体介导的轴突损伤;以及（iii）确定 内溶酶体ARESTA途径调节神经元轴突突变型PrP聚集体的形成 vivo.中心假设是（i）ARESTA驱动各种内分泌体的形成， 家族性朊病毒疾病与内吞途径内的辅因子的相互作用;（ii）突变型PrP 内分泌体诱导的病理作为轴突毒性中心， 损害局部轴突细胞器-细胞器相互作用，和（iii）内溶酶体途径 调节体内突变PrP聚集体的形成和病理学。拟议研究 是创新的，因为它提供了一个概念框架，开发模型，包括新的 内溶酶体途径介导的机制来解释轴突内聚集体如何形成， 在朊病毒病中损害神经元功能。这项研究意义重大，因为它 鉴定了内吞途径，特别是ARESTA和内吞体，作为抗- 用于治疗的聚集靶点以抑制聚集体形成并逆转相关病理。 当淀粉样蛋白-b肽，tau蛋白和大多数在神经变性中错误折叠的蛋白质在 内吞途径在某些时候，在他们的加工路线，我们的研究结果预计将是相关的 阿尔茨海默氏症和阿尔茨海默氏症相关的痴呆症。

Ultrastructural studies of human patient brains with prion disease have revealed the accumulation of misfolded PrP within dystrophic neurites inside endolysosomes. Other complex structures co- exist within these dystrophies and are now considered common features of prion pathologies, including autophagic vacuole-like membrane-bound organelles, lysosomal electron-dense bodies, and enlarged endolysosomes. The mechanisms leading to the formation of these structures remain unknown. Our studies have identified an endolysosomal pathway in mammalian neurons that we call axonal rapid endosomal sorting and transport-dependent aggregation (ARESTA), that drives the formation of neurotoxic axonal aggregates of a misfolded mutant prion protein (PrP) inside endo-membrane structures that we call “endoggresomes”. The long-term goal of this proposal is to characterize the endocytic pathways that play a role in the pathophysiology of prion diseases, Alzheimer’s disease, and of Alzheimer’s disease related dementias, that will provide actionable targets for their pharmacological treatment. The objectives of this proposal are (i) to determine the generality of the ARESTA pathway in formation of endoggresomes in axons of neurons expressing various familial PrP mutations, and to characterize the molecular and ultrastructural architecture of neurotoxic endoggresomes; (ii) to determine the mechanisms of mutant PrP endoggresome-mediated axonal impairments; and (iii) to determine how the endolysosomal ARESTA pathway modulates the formation of axonal mutant PrP aggregates in vivo. The central hypotheses are (i) ARESTA drives the formation of endoggresomes in various familial prion diseases by interactions with co-factors within endocytic routes; (ii) mutant PrP endoggresome-induced pathologies act as axonotoxicity hubs that inhibit neuronal function by impairing local axonal cytoskeletal-organelle interactions, and (iii) endolysosomal pathways modulate the formation and pathology of mutant PrP aggregates in vivo. The proposed research is innovative because it provides a conceptual framework for developing models that include novel endolysosomal pathway-mediated mechanisms to explain how intra-axonal aggregates form and impair neuronal function in the prionopathies. The proposed research is significant because it identifies the endocytic pathway and specifically ARESTA and endoggresomes, as anti- aggregation targets for therapies to inhibit aggregate formation and reverse related pathologies. As amyloid-b peptides, tau, and most proteins that misfold in neurodegeneration transit within endocytic routes at some point in their processing routes, our findings are expected to be relevant to Alzheimer’s disease and Alzheimer’s disease related dementias.