Activation of the 20S Proteasome to Normalize Tau Homeostasis

项目概要/摘要。 微管结合蛋白tau（MAPT/tau）累积引起一个十五人进行性 神经退行性疾病，包括额颞叶痴呆（FTD）、进行性核上性麻痹（PSP） 和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点是， tau稳态不平衡，导致其积累和聚集。因此，一种潜在的治疗方法 它们是为了增强tau蛋白通过蛋白酶体的通量。在衰老过程中，蛋白酶体的能力 途径似乎恶化，可能产生有利于异常tau积累的条件。它有 最近观察到许多细胞，包括神经元，含有大量的20 S蛋白酶体， 还没有完全激活。我们假设这些“潜伏”池可以被动员，以提高tau蛋白的周转。 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表达， 加速了tau的清除。现在，我们建议开发小分子，这些小分子是有效的和有选择性的 20 S蛋白酶体激动剂。为了实现这一目标，我们使用了基于结构的方法来识别小的 与20 S蛋白酶体上的变构位点结合的分子，这些变构位点负责“门控”20 S蛋白酶体的进入。 印刷受体.核磁共振研究表明，铅分子结合到预期的网站和EM研究表明， 与设计一致，它们“打开”20 S蛋白酶体。引人注目的是，我们发现这些分子 在体外刺激8 - 20倍蛋白酶体活性。铅分子也加速了 在基于细胞的模型中与疾病相关的tau，与模型一致。这个项目的下一个关键步骤是 （SA 1）追求化学系列的结构引导的、命中到铅的优化，以及（SA 2）表征 20 S蛋白酶体和tau稳态之间的关系。这项工作意义重大，因为它将提供 新的化学探针用于了解tau稳态，可能验证20 S作为一种新药 靶向tau蛋白病。这项工作是创新的，因为它采用了尖端的计算，结构和 产生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.