Activation of the 20S Proteasome to Normalize Tau Homeostasis

项目摘要/摘要。 微管结合蛋白tau(MAPT/tau)积聚导致一个15人的家族进行性进展 神经退行性疾病，包括额颞叶痴呆(FTD)、进行性核上性瘫痪(PSP) 以及某些形式的阿尔茨海默病(AD)。这些无法治愈的致命疾病的共同特征是 Tau的动态平衡失衡，导致其积聚和聚集。因此，一种潜在的治疗方法 它们是通过蛋白酶体增加tau的流量。在衰老过程中，蛋白酶体的能力 途径似乎恶化，潜在地创造了有利于tau异常积累的条件。它有 最近观察到，许多细胞，包括神经元，都含有大量的20s蛋白酶体，这些蛋白酶体 并未完全激活。我们推测，这些“潜在的”资金池可以被动员起来，以增加tau的周转。 事实上，已经知道显微注射活性蛋白酶体或蛋白酶体亚单位的过度表达 加快了tau的清除速度。现在，我们计划开发有效和选择性强的小分子 20年代蛋白酶体的激动剂。为了实现这一目标，我们使用了基于结构的方法来识别小型 与20S蛋白酶体上的变构位点结合的分子，负责“门控”进入 底物。核磁共振研究表明，铅分子结合到预定的位置，EM研究表明， 与设计一致的是，他们“打开”了20多岁的蛋白酶体。令人惊讶的是，我们发现这些分子 在体外刺激蛋白酶体活性8到20倍。铅分子还加速了 在基于细胞的模型中与疾病相关的tau，与该模型一致。这个项目的下一个关键步骤是 (SA1)追求化学系列的结构引导、点击到领先的优化和(SA2)表征 20s蛋白酶体与tau动态平衡的关系。这项工作意义重大，因为它将提供 用于了解tau动态平衡的新化学探针，可能验证20s是一种新药 紧张症的靶子。这项工作具有创新性，因为它使用了尖端的计算、结构和 产生一种重要酶的变构激动剂的实验方法。

Project Summary/Abstract. Microtubule-binding protein tau (MAPT/tau) accumulates to cause a family of fifteen progressive neurodegenerative disorders, incluing frontotemporal dementia (FTD), progressive supranuclear palsy (PSP) and some forms of Alzheimer's disease (AD). The common feature of these untreatable, fatal diseases is that tau homeostasis is imbalanced, resulting in its accumulation and aggregation. Thus, a potential way to treat them is to enhance the flux of tau through the proteasome. During aging, the capacity of the proteasome pathway appears to deteriorate, potentially creating conditions that favor abnormal tau accumulation. It has recently been observed that many cells, including neurons, contain substantial pools of 20S proteasome that are not fully activated. We hypothesize that these “latent” pools could be mobilized to enhance tau turnover. Indeed, it is already known that microinjection of active proteasome or over-expression of proteasome subunits speeds the clearance of tau. Now, we propose to develop small molecules that are potent and selective agonists of the 20S proteasome. Towards this goal, we have used structure-based methods to identify small molecules that bind to the allosteric sites on the 20S proteasome that are responsible for “gating” the entry of substrates. NMR studies showed that the lead molecules bind to the intended sites and EM studies show that, consistent with the design, they “open” the 20S proteasome. Strikingly, we found that these molecules stimulate proteasome activity between 8 to 20-fold in vitro. The lead molecule also accelerated turnover of disease-associated tau in cell-based models, consistent with the model. The next critical step in this project is to (SA1) pursue the structure-guided, hit-to-lead optimization of the chemical series and (SA2) characterize the relationships between the 20S proteasome and tau homeostasis. This work is significant because it will provide new chemical probes for use in understanding tau homeostasis, potentially validating the 20S as a new drug target for tauopathies. The work is innovative because it employs cutting-edge computational, structural and experimental approaches to generate allosteric agonists of an important enzyme.