Propagation of Lipid-Anchored Prion Aggregates

传染性海绵状脑病（tse），也称为朊病毒疾病，是一组影响多种哺乳动物的神经退行性疾病，包括绵羊和山羊（痒病）、宫颈类（慢性消耗性疾病）和人类（克雅氏病）。TSE疾病的一个中心事件涉及正常宿主细胞朊病毒蛋白（PrPC）转化为部分蛋白酶抗性、聚集性、疾病相关亚型（PrPSc）。tse诱导的病理通常与PrP-res沉积有关，但神经退行性变的机制尚不清楚。像朊病毒疾病一样，其他神经退行性疾病包括阿尔茨海默病和帕金森病在内的病理蛋白聚集体的沉积。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质的积累有关。朊病毒在宿主之间和宿主内部传播的关键过程包括神经侵袭和PrPSc的细胞间传播。通过糖基磷脂酰肌醇（GPI）锚定的PrP膜结合可能在调节这些过程中起重要作用。我们在这个项目中的工作重点是阐明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传播中的作用。

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 2013, we have continued 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 suggest that GPI-anchoring directs Sup35NM assembly into non-amyloid membrane-bound aggregates.