Investigating the Mechanism of Sup35 Prion Curing by Excess Hsp104

描述（由申请人提供）：在大多数情况下，蛋白质采用单一的三维折叠，指定其在体内的功能。有几种蛋白质质量控制途径有助于确保蛋白质采用其正确的折叠，并且不正确折叠的蛋白质被降解。这些蛋白质质量控制途径的破坏，特别是由于衰老，可能导致许多毁灭性的人类疾病。这些疾病中最严重的，例如阿尔茨海默病、帕金森病和亨廷顿病，是由原本正常的细胞蛋白质的自我永久错误折叠和聚集引起的。这些蛋白质聚集体的出现和持久性可通过抑制聚集蛋白质的功能或通过产生毒性聚集体而导致疾病状态。在任何一种情况下，聚集途径的控制都是病理进展的关键决定因素。虽然这些疾病相关的聚集体在体外是稳定的，但相同的复合物在体内似乎是动态的，这表明可以通过治疗干预来利用现有的细胞机制来靶向这些致病复合物以进行清除。关于错误折叠的蛋白质动力学，研究得最多的例子可能是酵母朊病毒蛋白Sup35。Sup35形成自我永存的、可遗传的聚集体，这些聚集体被分子伴侣Hsp104不断重塑。一个类似的重塑活动被认为是必不可少的发展和传播的自我永存的蛋白质聚集体在高等真核生物。当酵母中Hsp104水平升高时，Sup35朊病毒聚集体，而不是那些由其他朊病毒蛋白组成的聚集体，会随着时间的推移而丢失。虽然体外研究表明这种效应是由聚集蛋白的再溶解引起的，但现有的体内研究不支持这一假设。为了阐明这一过程的分子基础，我将确定两个特性的蛋白质聚集体，赋予易感性过量的Hsp104和机制，过量的Hsp104导致这些复合物的损失。这些研究将共同阐明体内错误折叠蛋白质的可溶性和聚集形式之间的动态平衡，揭示蛋白质解聚集在这一过程中的作用，并强调这一途径中可用于治疗干预的关键事件。许多破坏性的衰老相关疾病是由蛋白质质量控制途径的破坏引起的，这导致有毒蛋白质聚集体的积累。拟议的工作旨在阐明分子伴侣蛋白的作用机制，该蛋白在从细胞中去除聚集的蛋白质方面发挥作用，从而深入了解可能成为未来治疗目标的途径。

DESCRIPTION (provided by applicant): In most cases, proteins adopt a single three-dimensional fold that specifies their functions in vivo. There are several protein quality control pathways that help to ensure that proteins adopt their proper fold and that improperly folded proteins are degraded. The breakdown of these protein quality control pathways, particularly as a result of aging, can lead to a number of devastating human diseases. The most severe of these disorders, such as Alzheimer's, Parkinson's and Huntington's diseases are caused by the self- perpetuating misfolding and aggregation of otherwise normal cellular proteins. The appearance and persistence of these protein aggregates can lead to the disease state by inhibiting the function of the aggregated protein, or by producing toxic aggregates. In either case, control of the aggregation pathway is a key determinant in the progression of pathology. While these disease-associated aggregates are stable in vitro, the same complexes appear to be dynamic in vivo, suggesting that existing cellular mechanisms could be exploited through therapeutic intervention to target these pathogenic complexes for clearance. Perhaps the best-studied example of misfolded protein dynamics involves the yeast prion protein Sup35. Sup35 forms self-perpetuating, heritable aggregates that are continually remodeled by the molecular chaperone Hsp104. A similar remodeling activity is considered essential for the development and spread of self-perpetuating protein aggregates in higher eukaryotes. When Hsp104 levels are elevated in yeast, Sup35 prion aggregates, but not those comprised of other prion proteins, are lost over time. While in vitro studies suggest this effect results from resolubilization of aggregated protein, the available in vivo studies do not support this hypothesis. To elucidate the molecular basis of this process, I will determine both the characteristics of protein aggregates that confer susceptibility to excess Hsp104 and the mechanism by which excess Hsp104 leads to a loss of these complexes. Together, these studies will elucidate the dynamic equilibrium between soluble and aggregated forms of a misfolded protein in vivo, uncover the role of protein disaggregation in this process, and highlight key events in this pathway that could be exploited for therapeutic intervention. Many devastating aging-related diseases are caused by the breakdown of protein quality control pathways that lead to the buildup of toxic protein aggregates. The proposed work aims to elucidate the mechanism of action of a chaperone protein that functions in removing aggregated proteins from cells, providing insights into a pathway that could potentially be the target of future therapies.