Structure and Genesis of tau Filaments

描述(由申请人提供)：神经纤维性病变是阿尔茨海默病等神经退行性疾病的标志性病理。病变主要由tau组成，它是一种微管相关蛋白，通常具有促进微管组装、微管稳定性和细胞骨架完整性的功能。在疾病皮损中积累的tau蛋白在聚集状态和翻译后修饰方面不同于微管相关蛋白。尽管在描述宏观聚集途径方面取得了进展，但关于病变形成如何与分子水平上的事件或神经变性的细胞机制联系起来的共识尚未出现。为了解决这些关键问题，该实验室开发了强大的方法来量化体外tau的纤维化，一级动力学模型合理的组装行为，以及可能有助于检测和抑制tau聚集的紧密结合配体。在这些发现的基础上，假设在近生理条件下，tau通过部分折叠的中间体在成核-延伸机制中发生光化，并且该反应途径创建了可用于选择性结合小分子配体的新的药效团。进一步推测，翻译后修饰、突变和外源效应器通过选择性地与组装物种相互作用来触发或增强聚集。目前的提案有三个具体目标来检验这些假设。首先，将确定tau发光的动力学路径，最终将对反应进行数学模拟。其次，将利用定量分析和构效关系建立新型纤化抑制剂的作用机制，从而识别目标并阐明在这一过程中进行药物干预的可能性。最后，将确定翻译后修饰和致病突变的影响的分子机制。总之，这些数据将阐明伴随纤化的分子事件，以及在体内拮抗甚至逆转早期tau丝形成的可行性。

DESCRIPTION (provided by applicant): Neurofibrillary lesions are a hallmark pathology of tauopathic neurodegenerative disorders such as Alzheimer's disease. The lesions are composed primarily of tau, a microtubule-associated protein that normally functions to promote tubulin assembly, microtubule stability, and cytoskeletal integrity. The tau that accumulates in disease lesions differs from microtubule-associated protein in its state of aggregation and posttranslational modification. Despite progress in describing the macroscopic aggregation pathway, a consensus has not emerged on how lesion formation links to events on the molecular level or to the cellular mechanisms of neurodegeneration. To address these crucial questions, this laboratory developed powerful methods for quantifying tau fibrillization in vitro, a first-order kinetic model rationalizing assembly behavior, and tight-binding ligands potentially useful for detecting and inhibiting tau aggregation. On the basis of these findings, it is hypothesized that under near physiological conditions tau fibrillizes via a partially folded intermediate in a nucleation-elongation mechanism, and that the reaction pathway creates novel pharmacophores available for selective binding of small-molecule ligands. It is further postulated that posttranslational modifications, mutations, and exogenous effectors trigger or enhance aggregation by selectively interacting with assembly species. The present proposal has three Specific Aims that test these hypotheses. First, the kinetic pathway through which tau fibrillizes will be determined, culminating in a mathematical simulation of the reaction. Second, the mechanism of action of novel fibrillization inhibitors will be established using quantitative assays and structure-activity relationships, leading to target identification and clarification of the potential for pharmacological intervention in the process. Finally, the molecular mechanisms underlying the effects of posttranslational modifications and disease causing mutations will be determined. Together, these data will clarify the molecular events accompanying fibrillization, and feasibility of antagonizing and even reversing early stage tau filament formation in vivo.