Cell Specific Perturbations of the Proteome in Alzheimer's Disease

阿尔茨海默病(AD)是与衰老相关的认知功能下降的主要原因，影响着超过500万65岁以上的美国人，随着婴儿潮一代的老龄化，预计患者数量将攀升至1300万。由于突触连接和功能的逐渐变化，我们的学习和记忆能力随着年龄的增长而下降。在阿尔茨海默病(AD)和其他神经退行性疾病的早期阶段，突触异常通常也是神经元丢失的先兆。然而，我们才刚刚开始全面了解这些异常，它们对认知能力下降的贡献，以及潜在的机制。这一挑战在很大程度上归因于大脑的复杂性以及衰老和神经退化的病因。晚期阿尔茨海默病(AD)的特征包括细胞外淀粉样多肽和细胞内过度磷酸化的tau蛋白积聚，以及慢性神经炎。虽然家族性阿尔茨海默病的基因已经被确定，这为疾病的病因提供了实质性的线索，但散发性阿尔茨海默病背后的机制仍然是一个谜。虽然对大脑转录动力学的研究具有变革性，但转录动力学与蛋白质动力学并没有很好的相关性，因为蛋白质的合成、周转和亚细胞定位在空间和时间上比转录更严格地受到调控。研究表明，蛋白质稳定性随着年龄的增长而下降，从而使细胞不能管理不可避免的蛋白质错误折叠。我们的团队将基于生物正交非规范氨基酸(BONCAT)蛋白质标记，在动物模型中研究蛋白质动力学。这些方法使我们能够测量与AD相关的特定脑细胞类型中蛋白质合成和降解的动态。这些测量将提供有关正常细胞过程中断的新信息。我们合作提案的超乎寻常的目标是通过利用生物正交非规范氨基酸标记(BONCAT)和定量质谱仪(MS)的最先进方法来确定与AD相关的突触和神经元衰退的脑细胞类型贡献，从而弥合知识中的关键差距。

Alzheimer’s disease (AD) is the leading cause of aging-related cognitive decline, affecting more than 5 million Americans over 65 years old, and the number of patients is expected to climb to 13 million as baby boomers age. Our ability to learn and remember declines with age due to progressive changes in synaptic connectivity and function. Synaptic abnormalities also commonly precede neuronal loss during early stages of Alzheimer’s disease (AD) and other neurodegenerative disorders. However, we are only beginning to understand the full spectrum of these abnormalities, their contributions to cognitive decline, and the underlying mechanisms. This challenge is largely attributed to the complexity of the brain and etiologies of aging and neurodegeneration. Hallmarks of advanced Alzheimer’s disease (AD) include accumulations of extracellular amyloid peptides and intracellular hyperphosphorylated tau protein as well as chronic neuroinflammation. While genes for familial AD have been identified, which shed substantial light on the etiology of the disease, the mechanisms behind sporadic onset AD still remain a mystery. While studies of transcriptional dynamics in the brain have been transformative, transcriptional dynamics do not correlate well with protein dynamics because protein synthesis, turnover and subcellular localization are more tightly regulated spatially and temporally than transcription. Studies have suggested that proteostasis declines with age, impairing cells from managing the inevitable misfolding of proteins. Our team will study protein dynamics in animal models based on bio-orthogonal non-canonical amino acid (BONCAT) protein labeling. These methods allow us to measure dynamics in protein synthesis and degradation in specific brain cell types relevant to AD. These measurements will provide new information about the disruption of normal cellular processes. The overreaching goal of our collaborative proposal is to bridge critical gaps in knowledge by leveraging the state-of-the-art methods for bio-orthogonal non-canonical amino acid tagging (BONCAT) and quantitative mass spectrometry (MS) to identify brain cell-type contributions to synaptic and neuronal decline associated with AD.