Propagation of Lipid-Anchored Prion Aggregates

传染性海绵状脑病(TSEs)，又称Pron病，是一组影响多种哺乳动物的神经退行性疾病，包括绵羊、山羊(瘙痒病)、鹿瘟(Cervid Spp)。(慢性消耗性疾病)和人类(克雅氏病)。TSE病的一个中心事件涉及将正常宿主细胞内的Prion蛋白(PrPC)转换为部分抗蛋白酶的、聚集的、疾病相关的亚型(PrPSc)。TSE诱导的病理通常与PrP-res沉积有关，但其神经退行性变的机制尚不清楚。与Pron疾病一样，其他神经退行性疾病涉及病理性蛋白质聚集体的沉积，包括阿尔茨海默病和帕金森氏病。总的来说，这些疾病被称为蛋白质错误折叠疾病，因为它们与错误折叠的宿主蛋白的积累有关。PrPSc在宿主之间和宿主内部传递的关键过程包括神经入侵和PrPSc的细胞间传播。PrP通过糖基磷脂酰肌醇(GPI)锚点的膜结合可能在调控这些过程中起着重要作用。我们在这个项目中的工作集中在阐明GPI和其他形式的膜锚定在调节聚集倾向蛋白的聚集和细胞间扩散中的作用。 2014年，我们完成了实验，调查了膜锚定如何允许蛋白质聚集体作为Prion进行繁殖，以及膜锚定对自繁殖蛋白质聚集体结构的影响。其中一项研究涉及GPI锚定蛋白Sup35 NM-GPI膜结合聚集体的结构特征。在没有GPI锚定的情况下，Sup35 NM组装成淀粉样纤维。然而，我们用免疫金显微镜观察聚集体结构并用几种敏感的淀粉样蛋白染色的数据表明，GPI锚定引导Sup35 nm组装成非纤维膜结合的聚集体。我们还在一种新的TSE感染的神经元培养模型中研究了PrPC跨膜锚定对PrPSc增殖的影响。

Transmissible spongiform encephalopathies (TSEs), also known as prion diseases, are a group of neurodegenerative diseases affecting a wide variety of mammals including sheep and goats (scrapie), cervid spp. (chronic wasting disease), and humans (Creutzfeldt-Jakob disease). A central event in TSE disease involves the conversion of the normal host cellular prion protein (PrPC) to a partially protease-resistant, aggregated, disease-associated isoform (PrPSc). TSE-induced pathology is usually associated with PrP-res deposition, but the mechanism of neurodegeneration is not understood. Like prion diseases, other neurodegenerative diseases involve the deposition of pathological protein aggregates including Alzheimers and Parkinsons disease. Collectively, these diseases are termed protein misfolding diseases because they are associated with the accumulation of misfolded host proteins. Critical processes for transmission of prions between and within hosts include neuroinvasion and intercellular spread of PrPSc. The membrane association of PrP via a glycosylphosphatidylinositol (GPI)-anchor may have an important role in modulating these processes. Our work in this project is focused on elucidating the role of GPI and other forms of membrane anchoring in modulating the aggregation and intercellular spread of aggregation-prone proteins. In 2014, we completed experiments to investigate how membrane anchoring allows the propagation of protein aggregates as prions and the effects of membrane anchoring on the structure of self-propagating protein aggregates. One line of investigation involves the characterization of the structure of membrane-bound aggregates of a GPI-anchored protein called Sup35NM-GPI. Without GPI-anchoring, Sup35NM assembles into amyloid fibrils. However, our data visualizing aggregate structure by immunogold microscopy and staining with several sensitive amyloid stains showed that GPI-anchoring directs Sup35NM assembly into non-fibrillar membrane-bound aggregates. We also investigated the effects of transmembrane anchoring of PrPC on the propagation of PrPSc in a new neuronal culture model of TSE infection.