The Role of Competitive Forces in Prion Propagation and Appearance

竞争力量在朊病毒传播和出现中的作用

• 批准号: 8258008
• 负责人: TRICIA R. SERIO
• 金额: $ 28.53万
• 依托单位: UNIVERSITY OF ARIZONA
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8258008
• 关键词: Address; Appearance; Biogenesis; Biological Phenomena; Biology; Bovine Spongiform Encephalopathy; Cell physiology; Cells; Collection; Creutzfeldt-Jakob Syndrome; Disease; Dominant-Negative Mutation; Environment; Enzyme Inhibitor Drugs; Enzyme Inhibitors; Enzymes; Epigenetic Process; Etiology; Event; Foundations; Frequencies; Generations; Goals; Knowledge; Link; Mammals; Mission; Modeling; Molecular; Molecular Chaperones; Molecular Conformation; Monitor; Neurodegenerative Disorders; Organism; Pathway interactions; Phenotype; Prion Diseases; Prions; Process; Property; Protein Conformation; Protein Structure Initiative; Proteins; Public Health; Research; Role; Saccharomyces cerevisiae; Scrapie; System; Techniques; Testing; United States National Institutes of Health; Variant; Work; Yeasts; base; computer studies; conformer; fungus; in vivo; inhibitor/antagonist; insight; man; mutant; non-prion; novel; overexpression; prion hypothesis; simulation; sup35; therapy development; trait

DESCRIPTION (provided by applicant): According to the prion hypothesis, an alternative conformation of a normal, host-encoded protein, known as a prion, can function as an epigenetic determinant of transmissible phenotypic states in vivo. Once considered atypical, this process has been linked to an expanding range of previously enigmatic biological phenomena, such as the etiology of the transmissible spongiform encephalopathies (TSEs) and the non-Mendelian inheritance of a group of metastable traits in fungi, suggesting it is a widespread process through which organisms can access and perpetuate parallel phenotypic states. While the protein-only basis of these phenotypes is well documented, we have surprisingly limited insight into how transitions between them occur, despite their significance for normal cellular physiology. Our long-term goal is to reveal the pathways through which prion transitions are evoked in vivo. To gain this insight, we will exploit the manipulability of the Sup35/[PSI+] prion of S. cerevisiae. Prion propagation in this system, and also likely in mammals, occurs through a multi-step pathway of protein biogenesis that is influenced by both the inherent properties of the prion and by aspects of the cellular environment. [PSI+] propagation is normally efficient, but many conditions, with parallels in mammals, induce phenotypic transitions. The overall objective of this proposal is to combine empirical and computational studies to determine which step(s) of the in vivo prion propagation pathway are altered by these manipulations and the cellular pathways through which these changes evoke the switch. To date, most analyses have considered these effects from the perspective of the prion alone, but our proposed studies consider their action in the context of the entire system. While conditions that induce transitions between prion-associated phenotypes introduce different conformational or sequence variants of the prion into cells, the role of competitive forces in prion transitions has never been explored. We hypothesize that the crucial steps in the prion propagation pathway should be considered as enzyme-limited processes that are subject to competitive forces, which can effectively evoke phenotypic transitions. To directly test this hypothesis, we will determine: 1) the pathways by which dominant-negative mutants cure prions, 2) the pathways by which prion variants establish dominance, and 3) the molecular basis of the requirement for an existing prion in the de novo appearance of a second prion. Through this unique perspective, we will begin to reveal the cellular pathways underlying transitions between prion-associated phenotypes, a crucial yet poorly understood aspect of prion biology. PUBLIC HEALTH RELEVANCE: The proposed research is relevant to public health because the appearance of alternative, self-replicating protein conformations are associated with a wide array of familial, sporadic and transmissible neurodegenerative diseases in man. Our current inability to explain, predict or exploit transitions between normal and disease states is a critical barrier to progress in the development of treatments for these disorders. Our proposed studies are relevant to the mission of the NIH because the knowledge gained here will provide insight into the forces constraining switches between these states and the robustness of the system to external perturbation.

描述（由申请人提供）：根据朊病毒假说，正常宿主编码蛋白质的另一种构象（称为朊病毒）可以充当体内可传播表型状态的表观遗传决定因素。这一过程曾经被认为是非典型的，但它与一系列不断扩大的以前神秘的生物现象有关，例如传染性海绵状脑病（TSE）的病因学和真菌中一组亚稳态特征的非孟德尔遗传，表明这是一个广泛的过程，生物体可以通过该过程获得并维持平行的表型状态。虽然这些表型仅以蛋白质为基础已有充分记录，但令人惊讶的是，我们对它们之间的转变如何发生的了解有限，尽管它们对正常细胞生理学具有重要意义。我们的长期目标是揭示体内引发朊病毒转变的途径。为了获得这一见解，我们将利用酿酒酵母 Sup35/[PSI+] 朊病毒的可操作性。该系统中的朊病毒繁殖，也可能在哺乳动物中，通过蛋白质生物发生的多步骤途径发生，该途径受到朊病毒固有特性和细胞环境各方面的影响。 [PSI+] 繁殖通常是有效的，但许多条件（与哺乳动物中的情况相似）会诱导表型转变。该提案的总体目标是结合经验和计算研究，以确定体内朊病毒传播途径的哪些步骤被这些操作所改变，以及这些变化通过哪些细胞途径引起转换。迄今为止，大多数分析仅从朊病毒的角度考虑了这些影响，但我们提出的研究在整个系统的背景下考虑了它们的作用。虽然诱导朊病毒相关表型之间转变的条件将朊病毒的不同构象或序列变体引入细胞，但竞争力在朊病毒转变中的作用从未被探索过。我们假设朊病毒繁殖途径中的关键步骤应被视为受竞争力量影响的酶限制过程，可以有效地引发表型转变。为了直接检验这一假设，我们将确定：1）显性失活突变体治愈朊病毒的途径，2）朊病毒变体建立优势的途径，以及3）第二个朊病毒从头出现时对现有朊病毒的分子基础。通过这种独特的视角，我们将开始揭示朊病毒相关表型之间转变的细胞途径，这是朊病毒生物学的一个重要但仍知之甚少的方面。 公共健康相关性：拟议的研究与公共健康相关，因为替代性、自我复制蛋白质构象的出现与人类多种家族性、散发性和传染性神经退行性疾病有关。我们目前无法解释、预测或利用正常状态与疾病状态之间的转变，这是这些疾病治疗方法开发取得进展的关键障碍。我们提出的研究与 NIH 的使命相关，因为在这里获得的知识将有助于深入了解限制这些状态之间切换的力以及系统对外部扰动的鲁棒性。