TSE Prion Cell Biology

传染性海绵状脑病（tse）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）。我们的研究重点是朊蛋白（PrP），因为该蛋白在控制TSE发病机制的许多方面发挥着关键作用，如疾病易感性和种间传播。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。被称为朊病毒的传染因子的性质仍不确定，但被认为主要由错误折叠的PrP组成，可能与另一个宿主附属分子复合。PrPC是一种糖基磷脂酰肌醇（GPI）锚定的糖蛋白，大多数在体内产生的PrPSc含有这种GPI锚定蛋白。正常和疾病相关的PrP异构体的膜结合可能影响朊病毒疾病的许多特征和PrPC功能。除了确定哺乳动物朊病毒的生化组成外，我们的工作重点是阐明朊病毒的摄取、复制和传播机制。

Transmissible spongiform encephalopathies (TSEs) 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). Our studies are focused on the prion protein (PrP) due to the critical role of this protein in controlling many aspects of TSE pathogenesis such as susceptibility to disease and interspecies transmission. 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. The nature of the infectious agent, called a prion, remains uncertain but is thought to be composed primarily of misfolded PrP, perhaps in complex with another host accessory molecule(s). PrPC is a glycosylphosphatidylinositol (GPI)-anchored glycoprotein, and the majority of PrPSc produced in vivo contains this GPI anchor. Membrane association of both normal and disease-associated PrP isoforms may influence many features of prion disease and PrPC function. Our work is focused on elucidating mechanisms of uptake, replication, and spread of prions, in addition to determining the biochemical composition of mammalian prions. In 2014, we have continued the characterization of novel synthetic strains of TSE agents that originate from purified recombinant PrP and further investigated mechanisms of uptake, propagation, and intercellular spread of PrPSc via imaging studies in novel neuronal culture systems. Experiments associated with the former line of investigation indicate we have isolated a unique synthetic TSE prion completely dependent on GPI-anchorless PrPC for propagation. We have also explored the role of non-neuronal brain cells in TSE infections and found evidence that fibroblasts and astrocytes may play an important role at early time points of infection due to enhanced uptake of PrPSc compared to neurons. In collaboration with Motohiro Horiuchi's lab, we have also shown that trafficking of input PrPSc from the late endosomal/lysosomal pathway to the endocytic recycling pathway is important for establishment of prion infection in cells.