REPURPOSING PRION PROTEINS AS TRANSLATIONAL AMYLOID-TARGETING THERAPEUTICS FOR ALZHEIMER'S DISEASE

项目总结 长期以来，阿尔茨海默病(AD)和许多其他与年龄相关的痴呆患者的认知能力下降 与不溶的淀粉样斑块的存在有关，这些斑块破坏了正常的突触功能。然而， 最近的研究表明，阿尔茨海默病的突触损伤与 可溶性淀粉样β寡聚体(ABO)，而不是来自不溶性纤维。可溶低聚物在结构上 不规则和混杂地与膜蛋白结合，从而失调下游淀粉样蛋白组装 比如tau。不幸的是，这些性质也使得对ABO进行实验表征变得困难，因为 低聚物态可以是瞬时的，也可以作为噪声观察到。 多种全基因组筛选方法已将细胞蛋白(Prpc)确定为可能的靶标。 随后的研究证实了AD中存在涉及Abo-PrPc结合的病理生理途径。 有趣的是，ab单体和不溶性纤维不与PrPc结合，因此PrPc的结合域可以是 在多肽适体中开发，以靶向和稳定ABO。在这里，我们通过设计来利用这些交互 仿生PrPc多肽与可溶性ABO复合。分子模拟与淀粉样蛋白的表征 将结合实验优化适体-Abo相互作用，以取消Abo与PrPc的结合。 虽然适配子不太可能起到治疗AD的作用，但针对淀粉样蛋白的PrPc多肽可以引导 构建跨越血脑屏障并有效抑制ABO毒性的下一代试剂。 同样，通过适配子鉴定ABO可能能够通过以下途径追踪可溶性低聚物 不溶性纤维形成过程中的荧光标记。鉴于几乎没有任何方法论可以 以ABO为目标，这一提议将寻求分离可溶低聚物并确定它们相互作用的局限性 与膜蛋白结合。 为了协同结合分子动力学模拟和实验，指导将是 使用核磁共振波谱、层析和配基结合分析来测量齐聚物 结构、大小和结合PrP蛋白的能力。辅导将包括定期会议， 课程、研讨会和沉浸在主要导师的实验室中。此外，这项研究将寻求 通过模型适配子的翻译将基础生物物理研究与临床相关系统联系起来 从模拟到实验。结果将与阿尔茨海默氏症相关，并在此背景下进行解释 疾病。作为这项研究的结果而制定的方案和产品将随后通知后续行动 活细胞中可溶性淀粉样蛋白毒性的研究，扩展到多种神经退行性疾病。

PROJECT SUMMARY Cognitive decline in Alzheimer’s Disease (AD) and many other age-related dementias have long been associated with the presence of insoluble amyloid plaques that disrupt normal synaptic functioning. However, more recent studies have revealed that synapse impairment from AD is much more potently associated with soluble amyloid-beta oligomers (abo), rather than from insoluble fibrils. Soluble oligomers are structurally irregular and promiscuously bind to membrane proteins, thereby dysregulating downstream amyloid assemblies such as tau. These properties, unfortunately, have also made it difficult to experimentally characterize abo, since oligomeric states can be transient or otherwise observed as noise. Multiple genome-wide screening methods have identified cellular prion protein (PrPc) as a putative target of abo, and subsequent studies have confirmed a pathophysiological pathway in AD involving abo-PrPc binding. Interestingly, ab monomers and insoluble fibrils do not bind to PrPc, thus the binding domain of PrPc can be exploited in peptide aptamers to target and stabilize abo. Here, we seek to utilize these interactions by designing biomimetic PrPc peptides that complex soluble abo. Molecular simulations and amyloid-characterizing experiments will be combined to optimize aptamer-abo interactions in order to abrogate binding of abo to PrPc. While aptamers are unlikely to serve as an AD therapeutic, amyloid-targeting PrPc peptides can guide the construction of next-generation agents that cross the blood-brain barrier and potently inhibit the toxicity of abo. Similarly, identification of abo by aptamers can potentially enable the tracking of soluble oligomers through fluorescent tagging during the formation of insoluble fibrils. Given that there are few, if any methodologies to target abo, this proposal would seek to isolate soluble oligomers and identify the limitations of their interactions with membrane proteins. In order to synergistically combine molecular dynamics simulations with experiments, mentoring will be carried out on the use of NMR spectroscopy, chromatography, and ligand-binding assays to measure oligomer structure, size, and the ability to bind PrP proteins, respectively. Mentoring will include regular meetings, coursework, workshops, and immersion in the laboratory of the primary mentor. Additionally, this study will seek to bridge basic biophysical research with clinically-relevant systems through the translation of model aptamers from simulations into experiments. Results will be connected to and interpreted in the context of Alzheimer’s Disease. The protocols and products developed as a result of this study will subsequently inform follow-up studies of soluble amyloid toxicity in live cells, with extensions to multiple neurodegenerative diseases.