Protein Aggregation and Inclusion Body Formation

描述(由申请人提供)：蛋白质聚集体和泛素(Ub)积聚到细胞质包涵体(IB)是神经退行性疾病唯一最明确的诊断神经病理学标志。尽管具有普遍的诊断意义，但IB形成的细胞生物学机制，以及这些结构的形成是否反映了致病或保护过程，仍然是一个未解的谜。这项研究的长期目标是阐明IB形成和Ub沉积的分子机制，并对哺乳动物细胞如何响应致病的、易于聚集的蛋白质的长期表达有一个完整的理解。在上一个资助期，该项目支持的研究利用了对亨廷顿病(HD)细胞模型的单细胞分析，表明尽管成熟的IB包含聚集的亨廷顿蛋白(HTT)和Ub，但这两种蛋白质被招募到IB的动力学非常不同。这些观察结合神经退行性疾病遗传模型的新数据，提出了一种模型，在该模型中，像HTT这样的折叠缺陷聚集倾向蛋白的长期表达会加重细胞的蛋白质稳定能力(即细胞维持蛋白质折叠和降解之间正确的动态平衡的能力)，导致正常蛋白质从生产性折叠逐渐转移到泛素蛋白酶体系统，最终超过细胞降解蛋白质的能力。这项提案中的研究旨在使用最先进的蛋白质组和生物成像技术严格测试和完善这一新兴模型。这些研究将全面了解蛋白质聚集和蛋白稳态之间的动态相互作用，并将阐明神经退行性疾病生物学中存在时间最长的争议之一。 与公共卫生相关：美国人口老龄化预示着神经退行性疾病的流行。新出现的研究表明，这些疾病与脑细胞抵抗蛋白质合成、折叠和降解压力的能力密切相关。这项拟议的研究将利用最先进的方法学来了解细胞如何使用强大的神经退化遗传模型来处理这些应激源，并将为开发新的治疗靶点和生物标记物提供重要的见解。

DESCRIPTION (provided by applicant): Accumulation of protein aggregates and ubiquitin (Ub) into cytoplasmic inclusion bodies (IB) is the single most definitive diagnostic neuropathological marker of neurodegenerative disease. Despite this universal diagnostic significance, the cell biological mechanisms underlying IB formation and, indeed, whether formation of these structures reflects a pathogenic or protective process, remains an unresolved mystery. The long-term objective of this research project is to elucidate the molecular mechanisms that underlie IB formation and Ub deposition and to develop an integrated understanding of how mammalian cells respond to the chronic expression of pathogenic, aggregation-prone proteins. The research supported by this project during the previous funding period exploited single-cell analysis of a cellular model of Huntington's disease (HD) to show that, although mature IB contain both aggregated huntingtin (htt) and Ub, the two proteins are recruited to IB with vastly different kinetics. These observations, together with emerging data from genetic models of neurodegenerative disease, suggest a model in which chronic expression of a folding-defective aggregation-prone protein like htt, burdens the cell's proteostasis capacity (ie, the cell's ability to maintain the correct dynamic equilibrium between protein folding and degradation) leading to a progressive diversion of normal proteins from productive folding to the ubiquitin proteasome system, ultimately overwhelming the cell's capacity to degrade proteins. The research in this proposal aims to rigorously testand refine this emerging model using state-of-the-art proteomic and bioimaging technologies. These studies will provide a comprehensive understanding of the dynamic interaction between protein aggregation and proteostasis and will illuminate one of the longest-standing controversies in neurodegenerative disease biology. PUBLIC HEALTH RELEVANCE: The aging of the US population portends an epidemic of neurodegenerative disorders. Emerging research suggests that these diseases are closely associated with the capacity of brain cells to resist the stress of protein synthesis, folding and degradation. The proposed research will exploit state-of-the-art methodology to understand how cells deal with these stressors using a powerful genetic model of neurodegeneration, and will provide important insights into the development of new therapeutic targets and biomarkers.