Mechanisms of Prion Spread

朊病毒疾病是进展最快的神经退行性疾病之一， 病理学特征为细胞外朊病毒聚集，突触损伤，神经元损失， 以及大脑和脊髓的严重星形胶质细胞增生朊病毒聚集体通过 神经解剖学上连接的大脑区域，然而朊病毒如何从细胞到细胞的物理传播， 不太了解。在体外，朊病毒聚集体在质膜上、内体中形成， 在多泡体中，并且在来自慢性感染细胞的外来体中释放。一个主要 本申请的目的是确定细胞内泡状朊病毒运输如何有助于 细胞间朊病毒通过中枢神经系统传播的体外和体内模型 系统.我们以前采用了广泛的方法来跟踪结构 从轴突终末到神经元细胞体的多种朊病毒， 传播到中枢神经系统的高毒性朊病毒的特性。我们发现， 亚纤维和纤维朊病毒通过巨胞饮作用被神经元内化。然而，在这方面， 只有小的亚纤维朊病毒从神经组织部位扩散到大脑中。因此， 大小是朊病毒扩散到中枢神经系统的基础。我们还确定， 朊病毒蛋白的修饰可以改变聚集体的排列， 新的朊病毒株的出现。最后，我们发现自噬清除途径是 在携带朊病毒聚集体的肌细胞中诱导。在这次更新中，我们的目标是确定 朊病毒在神经元和神经胶质中的囊泡运输影响朊病毒通过CNS的扩散。在 具体目标1，我们将定义朊病毒的物理性质，这些物理性质决定了朊病毒包装成 外来体在具体目标2中，我们将确定细胞内朊病毒转化的关键调节因子， 通过操纵囊泡转运途径在神经元和星形胶质细胞中清除。另外我们 将表征囊泡调节蛋白在朊病毒感染的人类和小鼠中的表达 模型在具体目标3中，我们将确定细胞特异性抑制的早期和晚期 囊泡运输的阶段改变朊病毒疾病的进展。这些实验是 首先探测囊泡内朊病毒运输途径对朊病毒体内扩散的贡献， 并将有助于揭示囊泡运输如何影响朊病毒的转化，清除， 扩散到大脑随着越来越多的人，拟议的研究尤为重要。 认识到阿尔茨海默氏症和其他疾病中发生的内体和溶酶体功能障碍 神经退行性疾病，以及治疗干预的潜在机会 蛋白质聚集体清除途径。

Prion diseases are among the most rapidly progressive neurodegenerative disorders and are characterized pathologically by extracellular prion aggregates, synaptic damage, neuronal loss, and severe astrogliosis in the brain and spinal cord. Prion aggregates spread through neuroanatomically connected brain regions, yet how prions physically spread from cell-to-cell is poorly understood. In vitro, prion aggregates form on the plasma membrane, in endosomes, and in multivesicular bodies, and are released in exosomes from chronically infected cells. A major goal of this application is to determine how intra-cellular vesicular prion trafficking contributes to inter-cellular prion spread through the central nervous system using in vitro and in vivo model systems. We have previously employed a broad range of approaches to track structurally diverse prions from axon terminals to neuronal cell bodies and have determined the biophysical properties of highly virulent prions that spread into the CNS. We discovered that small, subfibrillar and fibrillar prions were internalized by neurons through macropinocytosis. However, only the small, subfibrillar prions spread from extraneural sites into the brain. Thus, aggregate size underlies prion spread into the CNS. We also determined that post-translational modifications in the prion protein can alter aggregate packing arrangements and lead to the emergence of new prion strains. Finally, we found that autophagic clearance pathways were induced in muscle cells harboring prion aggregates. In this renewal, we aim to determine how the vesicular trafficking of prions in neurons and glia impacts prion spread through the CNS. In Specific Aim 1, we will define the physical properties of a prion that govern packaging into exosomes. In Specific Aim 2, we will identify key regulators of intracellular prion conversion and clearance in neurons and astrocytes by manipulating vesicular transit pathways. Additionally we will characterize vesicular regulatory protein expression in prion-infected humans and in mouse models. In Specific Aim 3, we will determine how cell-specific repression of early and late stages of vesicular trafficking modifies prion disease progression. These experiments are the first to probe the contribution of intra-vesicular prion trafficking pathways to prion spread in vivo, and will help unravel how vesicular transport impacts prion conversion, clearance, and rapid spread through the brain. The proposed studies are particularly important with the growing recognition of endosomal and lysosomal dysfunction occurring in Alzheimer’s and other neurodegenerative diseases, and with potential opportunities arising for therapeutic intervention in protein aggregate clearance pathways.