In vivo targeting of unfolded protein to a phase-separated Huntingtin inclusion

所有主要的神经退行性疾病的特征在于大量聚集的神经退行性疾病。 中枢神经系统中的未折叠蛋白质。在神经退行性疾病中， 亨廷顿氏病（HD）是唯一简单的：HD的唯一原因是在亨廷顿氏病的基因组中的一类显性突变。 亨廷顿蛋白基因，其导致亨廷顿蛋白（Htt）中多聚谷氨酰胺重复区的扩增。 多聚谷氨酰胺束的长度与突变体Htt的不稳定性和解折叠增加相关 蛋白质，引起聚集。虽然Htt蛋白在整个生命过程中广泛表达于所有组织中，但只有 细胞亚群退化;大多数细胞能够耐受突变体Htt而没有显著的不良影响。怎么 细胞科普大量未折叠的蛋白质？许多研究发现， 聚集蛋白质的内含物与细胞死亡的相关性很差;相反， 寡聚聚集体更能预测细胞死亡。同样，在S.酿酒酵母，形成单一的 卵圆形突变体Htt包涵体正常生长，而许多广泛分布的Htt聚集体对 牢房这些观察使许多研究人员得出结论，内含物是细胞保护性的， 收集和清除有害小聚集物种的细胞机制。我们的研究 结果表明，mHtt包裹体是一个移动的相分离的隔间， 内含物与扩散通过细胞质的小聚集体的合并。证据表明 包涵体（IB）的形成是成核的，即使当泛素-蛋白酶体 系统能力过剩。我们的目标是阐明的机制，其中包被启动， 材料被纳入其中。通常，酵母细胞产生单个卵形突变体Htt IB，但IB不能 在许多携带单基因缺失的菌株中形成。两个基因是绝对必要的， 形成单个卵圆形内含物是伴侣蛋白;我们的证据表明伴侣蛋白与 其他蛋白质在体内将靶物质靶向IB。建议的工作将有助于我们更好地了解 在复杂的细胞环境中的伴侣系统的相互作用和额外的功能。重要的是这 项目还将促进PI的持续发展，并保持高度活跃的 在过去的三年里，该研究实验室为17名约克学院的本科生提供了培训。

All major neurodegenerative disorders are characterized by the accumulation of large aggregates of unfolded protein in the central nervous system. Among neurodegenerative disorders, the etiology of Huntington's Disease (HD) is uniquely simple: the sole cause of HD is a class of dominant mutations in the huntingtin gene, which lead to the expansion of a polyglutamine repeat region in the huntingtin protein (Htt). The length of the polyglutamine tract correlates with increased instability and unfolding of mutant Htt protein, causing aggregation. Although Htt protein is widely expressed in all tissues throughout life, only a subset of cells degenerate; most cells are able to tolerate mutant Htt without significant ill effect. How do cells cope with large quantities of unfolded protein? Many studies have found that the presence of large inclusions of aggregated protein correlates poorly with cell death; in contrast, the concentration of small oligomeric aggregates is more predictive of cell death. Similarly, in S. cerevisiae, cells that form a single ovoid mutant Htt inclusion grow normally, whereas numerous widely distributed Htt aggregates are toxic to the cell. These observations have led many researchers to conclude that inclusions are cytoprotective, a cellular mechanism for collecting and quarantining harmful small aggregative species. Our studies have shown that the mHtt inclusion is a mobile phase-separated compartment that grows through the coalescence of the inclusion with small aggregates that diffuse through the cytoplasm. Evidence suggests that the formation of an inclusion body (IB) is nucleated and occurs even when the ubiquitin-proteasome system has excess capacity. Our goal is to elucidate the mechanisms by which inclusions are initiated and material is incorporated into them. Typically, a yeast cell develops a single ovoid mutant Htt IB, but IBs fail to form in a number of strains carrying single-gene deletions. Two genes that are absolutely required to form single ovoid inclusions are chaperone proteins; our evidence suggests that chaperones cooperate with other proteins in vivo to target material to IBs. The proposed work will help us better understand the interactions and additional functions of chaperone systems in the complex cellular milieu. Importantly, this project will also facilitate the continued development of the PI, as well as maintaining a highly active research lab that has provided training for 17 York College undergraduates in the past three years.