Investigation of the yeast prion factor (PSI+)

酵母朊病毒因子（PSI）的研究

• 批准号: 7280429
• 负责人: SUSAN W LIEBMAN
• 金额: $ 41.3万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-01 至 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7280429
• 关键词: Affect; Alzheimer' s Disease; Amyloid; Appearance; Biological Models; Biology; Cell Extracts; Cells; Chromatin Remodeling Factor; Creutzfeldt-Jakob Syndrome; Epigenetic Process; Etiology; Fiber; Genes; Genetic; Homologous Gene; Huntington Disease; In Vitro; Individual; Infection; Investigation; Learning; Maintenance; Mammals; Memory; Molecular Conformation; Morphology; Neurodegenerative Disorders; Parkinson Disease; Phenotype; Plasmids; Prions; Process; Property; Protein Conformation; Protein Overexpression; Protein Structure Initiative; Proteins; Proteomics; Reaction; Role; Seeds; Specificity; Structure; System; Testing; Transcriptional Regulation; Variant; Yeasts; daughter cell; epigenetic variation; in vivo; member; non-prion; novel; physical property; prion biogenesis; protein folding; research study; segregation

DESCRIPTION (provided by applicant): Certain proteins can exist in distinct heritable conformations. In their "prion" conformation, they form amyloid-like aggregates and seed the joining of non-prion molecules of the same protein to the aggregates. Since similar alterations in protein conformations are associated with neurodegenerative diseases such as Alzheimer's, Huntington's, Parkinson's and Creutzfeldt-Jacob disease, exploring the underlying mechanisms that dictate prion biology will provide a better understanding of the etiology of these diseases. This novel prion mechanism of epigenetic variation exists in yeast. Investigations of new yeast prions will clarify the different roles of heritable protein conformations and the relationships between prions. Prion candidates have been, and will be, retrieved from genetic and proteomic screens. Prionization of two candidates, Cyc8 and Swi1, members of transcriptional regulation and chromatin remodeling complexes, would have global effects on the cell. A prion-protein candidate that may be involved with memory storage (CPEB) and mammalian homologs of the yeast [PSI+] prion protein will also be studied in the yeast system. Curiously, different heritable "strains" or variants of individual prions (with identical primary sequences) exist in both mammals and yeast. The causes of variant specific phenotypic differences will be investigated by studying the physical properties and structures of variant-specific yeast prion fibers made in vitro and by identifying the proteins associated with prion aggregates in cells. The efficiencies with which variants of one prion can "cross-seed" the de novo formation of another prion will be tested in vitro using variant specific fibers. Subparticles of prion aggregates extracted from cells will be tested for infectivity and variant specificity to learn if these subspecies are infectious. Paradoxically, certain prion variants that enhance the de novo appearance of the heterologous [PSI+] prion, also eliminate already existing [PSI+]. To investigate this we will examine the segregation of [PSI+] "seeds" into daughter cells during the curing process. Similar experiments will examine the mechanism by which heterologous QN-rich aggregates destabilize [PSI+]. To investigate how prion seeds first arise in the absence of infection, genes that enhance or inhibit de novo appearance or propagation of a prion will be identified and their roles in prion biogenesis will be defined. These are likely to include proteins involved in protein folding and degradation, and others. Finally, the mechanisms of prion propagation and de novo prion seed formation will be compared by in vitro analysis.

描述(申请人提供)：某些蛋白质可以以不同的可遗传构象存在。在它们的“Prion”构象中，它们形成淀粉样聚集体，并使相同蛋白质的非Prion分子加入到聚集体中。由于蛋白质构象的类似变化与阿尔茨海默氏症、亨廷顿氏症、帕金森氏症和克雅氏病等神经退行性疾病有关，因此探索决定蛋白生物学的潜在机制将有助于更好地理解这些疾病的病因学。这种新的表观遗传变异的Pron机制存在于酵母中。对新的酵母普里恩的研究将阐明可遗传蛋白质构象的不同作用以及普恩之间的关系。已经并将从基因和蛋白质组筛查中检索到普恩候选基因。转录调控和染色质重塑复合体的成员Cyc8和Swi1这两个候选基因的原始化将对细胞产生全局影响。一种可能参与记忆存储(CPEB)的Pron候选蛋白和酵母[PSI+]Prion蛋白的哺乳动物同源蛋白也将在酵母系统中进行研究。奇怪的是，哺乳动物和酵母中都存在不同的可遗传“品系”或不同的变异株(具有相同的初级序列)。通过研究体外制备的变异特异性酵母蛋白纤维的物理性质和结构，以及鉴定与细胞中蛋白聚集体相关的蛋白质，将研究变异特异性表型差异的原因。我们将使用不同的特殊纤维，在体外测试一种不同的普恩病毒变体与另一种普恩病毒的从头形成“交叉播种”的效率。从细胞中提取的普恩聚集物的亚颗粒将被测试感染性和变异特异性，以了解这些亚种是否具有传染性。矛盾的是，某些Prion变体可以增强异源[PSI+]Prion的从头出现，同时也消除了已经存在的[PSI+]。为了研究这一点，我们将研究在固化过程中[PSI+]“种子”进入子细胞的分离情况。类似的实验将检验富含QN的异源聚集体破坏[PSI+]稳定的机制。为了研究在没有感染的情况下Prion种子是如何首先出现的，将识别促进或抑制Prion从头出现或繁殖的基因，并确定它们在Prion生物发生中的作用。这些可能包括与蛋白质折叠和降解有关的蛋白质等。最后，将通过体外分析比较PrP的繁殖和从头开始的Pron种子形成的机制。