Genetic Study of the Yeast Prion-Interacting Proteins

描述（由申请人提供）：朊病毒是一种自我延续的蛋白质亚型，在哺乳动物和人类中引起致命的神经退行性疾病，并控制酵母的遗传性状。迄今为止已知的大多数朊病毒形成高度有序的纤维聚合物（淀粉样蛋白），类似于非传染性淀粉样蛋白病（如阿尔茨海默病和帕金森病）或多谷氨酰胺疾病（如亨廷顿病）的聚集体。清除淀粉样蛋白的机制尚不清楚。我们和其他研究小组表明，朊病毒在酵母中的繁殖发生在由伴侣蛋白介导的聚合物断裂和生长的后续循环中。在某些条件下，在酵母中观察到朊蛋白或其他淀粉样蛋白的细胞学上可检测的大聚集结构（包涵体）的积累，有时与细胞毒性有关。我们的数据表明，一些包涵体与肌动蛋白细胞骨架网络相互作用，参与内吞作用和内吞囊泡到液泡的运输。本文提出：1)包涵体是朊病毒产生或消除途径的中间体；2)朊病毒的繁殖受活跃增殖的朊病毒单位与不能有效繁殖的包涵体之间的动态平衡调节。伴侣蛋白、蛋白水解系统、细胞骨架网络和转运途径通过改变包体体和增殖朊病毒单位之间的平衡来调节朊病毒的繁殖和清除。我们对下一个预算期的建议旨在测试基于这一一般模型的具体预测。该项目的具体目标将具体解决伴侣、蛋白水解途径、细胞骨架网络和细胞内运输途径在朊病毒蛋白聚集体的产生和清除中的作用。综上所述，这些实验的结果将揭示酵母细胞中聚集的淀粉样蛋白的清除机制。与公共卫生相关：哺乳动物朊病毒疾病和许多其他淀粉样病是致命的和无法治愈的。哺乳动物朊病毒疾病，如“疯牛病”和麋鹿和鹿的慢性消耗性疾病，由于有可能传播给食用受感染肉类的人，对健康构成重大威胁。一些淀粉样蛋白疾病，如阿尔茨海默病，是普遍存在的，并且与年龄有关，因此，随着其他疾病的根除和人类平均寿命的提高，它们的重要性将进一步增加。本研究将进一步建立酵母作为对抗朊病毒和其他有毒淀粉样蛋白积累和繁殖策略的模型。

DESCRIPTION (provided by applicant): Prions are self-perpetuating protein isoforms that cause fatal neurodegenerative diseases in mammals and humans and control heritable traits in yeast. Most prions known to date form highly ordered fibrous polymers (amyloids), resembling aggregates involved in non-transmissible amyloidoses, such as Alzheimer's and Parkinson's diseases, or in polyglutamine disorders such as Huntington's disease. Mechanisms of clearance of the amyloid proteins are poorly understood. It is shown by us and other groups that prion propagation in yeast occurs via subsequent cycles of polymer fragmentation and growth, mediated by chaperone proteins. Accumulation of the large cytologically detectable aggregated structures (inclusion bodies) of prion proteins or other amyloidogenic proteins is observed in yeast in certain conditions and is sometimes associated with cytotoxicity. It is demonstrated by our data that some inclusion bodies interact with actin cytoskeletal networks, involved in endocytosis and trafficking of the endocytic vesicles to the vacuole. It is proposed that: 1) inclusion bodies represent intermediates in the prion generation or prion elimination pathways, and 2) prion propagation is regulated by a dynamic equilibrium between the actively proliferating prion units and inclusion bodies incapable of efficient propagation. Chaperones, proteolytic systems, cytoskeletal networks and trafficking pathways modulate prion propagation and clearance by shifting the equilibrium between inclusion bodies and proliferating prion units. Our proposal for the next budget period is designed to test specific predictions based on this general model. Specific aims of the project will specifically address the roles of chaperones, proteolytic pathways, cytoskeletal networks and intracellular trafficking pathways in generation and clearance of the prion protein aggregates. Taken together, the results of these experiments will uncover the mechanism of clearance of aggregated amyloidogenic proteins in yeast cells Relevance to public health: Mammalian prion diseases and many other amyloidoses are fatal and incurable. Mammalian prion diseases, such as "mad cow" disease and chronic wasting disease of elk and deer, represent a significant health threat due to a possibility of their transmission to humans with infected meat. Some amyloid diseases, such as Alzheimer's disease, are widespread and age-dependent, so that their importance is going to grow further in parallel with the eradication of other diseases and improvement of the average life span of human populations. This research will further establish yeast as a model for development of the strategies counteracting accumulation and propagation of prions and other toxic amyloids.