Genetic Study of the Yeast Prion-Interacting Proteins

描述(申请人提供)：Prion是一种自我延续的蛋白质亚型，在哺乳动物和人类中会导致致命的神经退行性疾病，并控制酵母中的可遗传特征。到目前为止，已知的大多数Prion形成高度有序的纤维聚合物(淀粉样蛋白)，类似于非传播性淀粉样变性，如阿尔茨海默氏症和帕金森氏病，或多谷氨酰胺疾病，如亨廷顿病。淀粉样蛋白清除的机制还知之甚少。我们和其他研究小组发现，在酵母中，Pron的繁殖是通过随后的聚合物裂解和生长循环进行的，由伴侣蛋白介导。在某些条件下，酵母菌中可以观察到Pron蛋白或其他淀粉样蛋白的大的、细胞学上可检测到的聚集结构(包涵体)，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小泡向液泡的运输。我们认为：1)包涵体代表了Prion产生或消除路径中的中间产物，2)Pron的传播受活跃增殖的Pron单位和不能有效繁殖的包涵体之间的动态平衡调节。伴侣蛋白、蛋白分解系统、细胞骨架网络和运输途径通过改变包涵体和增殖的普恩单位之间的平衡来调节普恩的传播和清除。我们对下一个预算期的提议是为了检验基于这一一般模型的具体预测。该项目的具体目标将具体涉及伴侣蛋白、蛋白分解途径、细胞骨架网络和细胞内运输途径在Pron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清除与公共健康相关的机制：哺乳动物的Pron疾病和许多其他淀粉样变性是致命的和不可治愈的。哺乳动物的Pron疾病，如疯牛病和麋鹿慢性消耗性疾病，由于它们可能通过受感染的肉类传播给人类，因此是一个重大的健康威胁。一些淀粉样疾病，如阿尔茨海默病，是普遍的和年龄相关的，因此它们的重要性将随着其他疾病的根除和人类人口平均寿命的提高而进一步增长。这项研究将进一步建立酵母作为发展策略的模型，以对抗Pron和其他有毒淀粉样蛋白的积累和繁殖。

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.