Patient-Based Structural Biology of Tauopathies and TDP-43 Proteinopathies using Cryo-Electron Microscopy and Mass Spectrometry

阿尔茨海默病(AD)tau细丝原子模型的发展带来了几个新的机会，包括识别高亲和力配体或抗体以检测AD tau细丝(即PET配体、小分子化合物、免疫治疗、生物标记物)的能力，并提供了需要从建模角度概括的基本特征的明确指示。鉴于肌萎缩侧索硬化症是复杂的致病实体，在临床表现、病程和基本病理上具有显著的异质性，因此，正在开发的工具能够检测/识别观察到的实际病理是至关重要的。因此，本项目的总体目标是表征tau细丝在tauopathy中的异质性，并利用定义散发性和家族性疾病中tau和TDP-43细丝形态的结构特征来提供对发病机制和毒性的新见解。特别是，我们将评估和比较AD和慢性创伤性脑病(CTE)之间tau丝的异质性，并开发新的资源来检测和模拟这些不同的tau病。利用冷冻电子显微镜(Cryo-EM)的类似方法也将用于解决额颞叶变性(FTLD)的细丝结构，FTLD是仅次于AD的第二大最常见的痴呆原因。由于FTLD的病理特征通常是tau(FTLD-tau)或TDP-43(FTLD-TDP)的异常沉积，因此我们将在散发性和家族性FTLD中建立tau和TDP-43细丝的原子模型。在我们最近发现的tau和TDP-43的新型翻译后修饰(PTM)的结构洞察力的基础上，我们将结合冷冻-EM、质谱学、分子生物学和生化方法来评估特定修饰对聚集倾向的贡献。这些结果将指导继续开发资源，以最好地检测病理学的特定方面并建立模型。

The development of an atomic model of tau filaments in Alzheimer’s disease (AD) has opened several new opportunities, including the ability to identify high-affinity ligands or antibodies to detect AD tau filaments (i.e., PET ligands, small molecule compounds, immunotherapy, biomarkers) and providing a clear directive about essential features that need to be recapitulated from a modeling perspective. Given that tauopathies are complex, pathogenic entities with significant heterogeneity in clinical presentation, disease course, and underlying pathology, it is essential that the tools under development are capable of detecting/recognizing the actual pathologies observed. As such, the overall goals of the current project are to characterize the heterogeneity of tau filaments across tauopathies, and to utilize structural features that define tau and TDP-43 filament morphology in sporadic and familial forms of disease to provide novel insight into pathogenesis and toxicity. In particular, we will assess and compare tau filament heterogeneity between AD and chronic traumatic encephalopathy (CTE) and develop novel resources to both detect and model tau in these distinct tauopathies. Similar methodology utilizing cryo-electron microscopy (cryo-EM) will also be employed to resolve filament structure in frontotemporal lobar degeneration (FTLD), which is the second most common cause of dementia after AD. As FTLD is usually characterized pathologically by the aberrant deposition of either tau (FTLD-tau) or TDP-43 (FTLD-TDP), we will develop atomic models of both tau and TDP-43 filaments in sporadic and familial forms of FTLD. Overlaying structural insights with our recent discovery of novel post-translational modifications (PTMs) of tau and TDP-43, we will assess the contribution of specific modifications to aggregation propensity, utilizing a combination of cryo-EM, mass spectrometry, molecular biology and biochemical approaches. These results will guide the continued development of resources to best detect and model particular aspects of pathology.