RNA binding proteins as novel targets in Alzheimer's disease

 描述(由申请人提供)：这项提案调查了微管相关蛋白tau(MAPT)的错误折叠和聚集的新机制，我们假设它提供了一个尚未被认识的但主要的病理生理学方面，如阿尔茨海默病(AD)。我们最近在AD中发现了一种新型的分子病理学，它源于RNA结合蛋白的聚集，形成包括应激颗粒的RNA-蛋白质复合体。这些应激颗粒逐渐积累在转基因直立性脑病模型的大脑中，并在患有AD和FTDP-17的受试者中大量积累。这项研究的起源来自于简单的观察：1)RNA结合蛋白通过一种显著的可逆聚集形成RNA颗粒，这是在生理调节下的；2)MAPT与一些RNA结合蛋白结合，包括TIA-1。RNA颗粒整合转录本用于运输、储存和/或降解。我们的结果表明，TIA-1刺激MAPT的磷酸化和错误折叠，MAPT刺激TIA-1阳性应激颗粒的形成；MAPT与应激颗粒的结合减少了其降解，似乎稳定了不溶性MAPT。阿尔茨海默病的慢性可能导致应激颗粒的过度形成和MAPT的聚集，从而导致神经变性。我们假设MAPT和RNA结合蛋白表现出双向调节。MAPT促进RNA颗粒的形成和稳定，包括应激颗粒。相反，RNA结合蛋白和翻译信号级联刺激MAPT的磷酸化和错误折叠。这一假设将在三个目标的背景下进行研究：目标1将确定TIA-1与MAPT相互作用的机制。我们将使用结构研究、成像和质谱学来突出发现关键结合蛋白的关键变化。目的2确定MAPT在神经元RNA颗粒生物学中的作用，包括应激颗粒。这个目标将使用活细胞成像来探索这一生物学，以探索基础和应激条件下RNA颗粒的动力学，并将检查MAPT是否调节与特定RNA颗粒/应激颗粒相关的转录本类型(使用iCLIP)。最后，目标3将确定应激颗粒/RNA翻译通路是否调节体内MAPT介导的神经变性。这一目标将集中在我们的初步研究中使用的RNA结合蛋白(例如TIA-1)以及通过质谱学鉴定的新的MAPT/Stress颗粒成分。

 DESCRIPTION (provided by applicant): This proposal investigates a novel mechanism for the misfolding and aggregation of microtubule associated protein tau (MAPT), which we hypothesize provides an unrecognized but major aspect of the pathophysiology of tauopathies, such as Alzheimer's disease (AD). We have recently identified a new type of molecular pathology in AD that derives from the aggregation of RNA binding proteins, forming RNA-protein complexes that include stress granules. These stress granules progressively accumulate in the brains of transgenic models of tauopathy, as well as massively accumulate in subjects with AD and FTDP-17. The genesis of this research comes from the simple observations that 1) RNA binding proteins form RNA granules through a striking property of reversible aggregation, which is under physiological regulation, and 2) MAPT binds to some RNA binding proteins, including TIA-1. RNA granules consolidate transcripts for transport, storage and/or degradation. Our results suggest that TIA-1 stimulates phosphorylation and misfolding of MAPT, and that MAPT stimulates formation of TIA-1 positive stress granules; the association of MAPT with stress granules reduces its degradation and appears to stabilize insoluble MAPT. The chronic nature of AD might lead to excessive formation of stress granules and aggregation of MAPT, contributing to neurodegeneration. We hypothesize that MAPT and RNA binding proteins exhibit bidirectional regulation. MAPT promotes the formation and stability of RNA granules, including stress granules. Conversely, RNA binding proteins and the translational signaling cascade stimulate the phosphorylation, and misfolding of MAPT. This hypothesis will be studied in the context of three aims: Aim 1 will determine the mechanisms by which TIA-1 interacts with MAPT. We will use structural studies, imaging and mass spectroscopy to highlight key changes in discover key binding proteins. Aim 2 will determine the role of MAPT in neuronal RNA granule biology, including stress granules. This aim will explore this biology using live cell imaging to explore RNA granule dynamics under basal and stress conditions and will examine whether MAPT modulates the types of transcripts associated with particular RNA granules/ stress granules (using iCLIP). Finally, Aim 3 will determine whether stress granule/RNA translation pathways regulate MAPT-mediated neurodegeneration in vivo. This aim will focus on the RNA binding proteins used in our preliminary studies (e.g., TIA-1) as well as the novel MAPT/ stress granule components identified by mass spectroscopy.