The tau code of Alzheimer's disease

描述（由申请人提供）：阿尔茨海默病（AD）的部分定义是由微管相关蛋白tau组成的细胞内包涵体的出现。在高度流行的散发性AD中，驱动tau聚集的机制尚不完全清楚，但似乎涉及异常的翻译后修饰。为了深入了解AD中伴随tau病变形成的修饰，我们使用质谱方法对从真实疾病组织标本中分离的tau聚集体进行了初步的结构分析。我们的研究结果表明，一种以前未被认识到的tau修饰，赖氨酸甲基化，与tau聚集体共纯化。初步甲基化特征涉及已知介导tau泛素化和其他翻译后修饰的位点，这表明甲基化是一种正常的tau修饰，也是影响疾病中tau病变形成的候选位点。我们现在提出了一个探索性项目来验证甲基化作为一种病理生理的tau修饰，将其置于与死后人体组织中分离的正常和聚集的tau相关的修饰特征的背景下，并初步了解其对tau聚集倾向和微管聚合活性的潜在影响。在达到本研究提出的里程碑之后，AD领域将获得必要的关键信息，以研究tau蛋白翻译后修饰之间潜在的串导，指导未来鉴定作用于tau蛋白的甲基转移酶和去甲基化酶，并鉴定可能有助于AD死前评估的新型疾病相关表位。

DESCRIPTION (provided by applicant): Alzheimer's disease (AD) is defined in part by the appearance of intracellular inclusions composed of the microtubule associated protein tau. The mechanisms that drive tau aggregation in the highly prevalent sporadic form of AD are not fully understood, but appear to involve abnormal post-translational modifications. To gain insight into the modifications that accompany tau lesion formation in AD, we conducted a preliminary structural analysis of tau aggregates isolated from authentic disease tissue specimens using mass spectrometry methods. Our results revealed that a previously unrecognized tau modification, lysine methylation, copurified with tau aggregates. The preliminary methylation signature involved sites that are known to mediate tau ubiquitylation and other post-translational modifications, suggesting that methylation is a normal tau modification and a candidate for influencing tau lesion formation in disease. We now propose an exploratory project to validate methylation as a pathophysiological tau modification, to place it into the context of modification signatures associated with both normal and aggregated tau isolated from post-mortem human tissue, and to gain preliminary insight into its potential effects on tau aggregation propensity an microtubule polymerization activity. Upon achieving the milestones proposed in this study, the AD field will gain the key information necessary to investigate potential cross-talk among tau post-translational modifications, to guide future identification of methyltransferases and demethylases that act on tau protein, and to identify novel disease-associated epitopes that may aid in the pre-mortem assessment of AD.