Defining the role of SINE retrotransposons and inflammasome activation in Alzheimer's disease

项目总结 阿尔茨海默病(AD)的病理特征包括淀粉样蛋白(Aβ，Aβ)斑块沉积和 过度磷酸化的Tau聚集体在神经纤维缠结中的积累。这些聚集体一直是 证明能激活炎症小体信号。炎症体是一种先天免疫平台，与 许多慢性神经退行性和炎症性疾病，如阿尔茨海默病。炎性小体抑制正在进行 探讨作为AD和其他复杂神经炎性/退行性疾病的治疗策略，包括 帕金森病、多发性硬化症和老年性黄斑变性(AMD)。最近的研究表明 发现了转座元件(TES)调节失调与AD之间的联系。我们已经建立了一个关键的 一类TES-短散布元素(SINES)活性在糖尿病发病机制中的作用 AMD。我们已经证明，在AMD中，Sine RNA的积聚通过Dual 激活NLRP3和NLRC4炎性小体。此外，我们还鉴定了DDX17，一种RNA解旋酶， 作为Sine RNA的分子传感器，它允许炎症体的双重激活。而且，我们的 初步研究发现，在5xFAD中，Aβ沉积的空间邻近区域存在Sine RNA的失调 阿尔茨海默病模型及新型NLRC4-NLRP3信号小分子抑制剂抑制炎症体的研究 Aβ聚合体诱导的激活。 尽管有这些发现，关于阿尔茨海默病的Sine RNA和炎症体的主要知识差距仍然存在， 例如，AD中Sine RNA的细胞来源尚未确定，Sine RNAs是否与其相互作用并激活 阿尔茨海默病的炎症体成分尚不清楚。这项提议将检验AD病理是 内源性Sine RNA积累诱导的NLRP3/NLRC4活化加剧。我们将对此进行测试 假设通过三个特定的目标：1)我们将定量Sine RNA的表达和炎症体的激活和 在AD的5xFAD模型中定位它们的细胞起源；2)我们将确定Sine RNA- 诱导脑小胶质细胞炎性小体激活，Sine RNA是否影响β吞噬功能 小胶质细胞，以及炎性小体抑制剂是否促进Aβ吞噬功能；以及3)我们将测试 单独和双重炎症体抑制剂对β清除以及认知和行为障碍的影响 5xFAD模型。总而言之，这些主题相关但独立的目标将阐明 Sine RNAs诱导AD大鼠炎性小体激活。本项目响应RFA-AG-22-021，因为它将(A) 确定Sine RNA和神经炎症之间的功能作用和因果关系；(B)定义 支持对Sine RNA的先天和免疫反应的机制；和(C)测试治疗干预措施 干扰Sine RNA介导的分子通路。这些研究将提供更深层次的机制 理解TES的作用，为未来的翻译研究奠定基础。

PROJECT SUMMARY Pathological hallmarks of Alzheimer's disease (AD) include deposition of Amyloid-β (Aβ) plaques and accumulation of hyperphosphorylated Tau aggregates in neurofibrillary tangles. These aggregates have been demonstrated to activate inflammasome signaling. Inflammasomes are innate immune platforms implicated in numerous chronic neurodegenerative and inflammatory conditions such as AD. Inflammasome inhibition is being explored as a therapeutic strategy for AD and other complex neuroinflammatory/degenerative disorders including Parkinson's disease, multiple sclerosis, and age-related macular degeneration (AMD). Recent studies have identified links between dysregulation of transposable elements (TEs) and AD. We have established a critical mechanistic role for activity of one class of TEs – short interspersed elements (SINEs) – in the pathogenesis of AMD. We have demonstrated that SINE RNA accumulation induces cellular degeneration in AMD by dual activation of the NLRP3 and NLRC4 inflammasomes. Furthermore, we have identified DDX17, an RNA helicase, as the molecular sensor of SINE RNAs that licenses dual activation of the inflammasomes. Moreover, our preliminary studies have identified dysregulation of SINE RNAs in spatial proximity to Aβ deposits in the 5xFAD model of AD and that a novel small molecule inhibitor of NLRC4-NLRP3 signaling suppresses inflammasome activation induced by Aβ aggregates. Notwithstanding these findings, major gaps in knowledge about SINE RNAs and inflammasomes in AD persist, e.g, the cellular sources of SINE RNAs in AD are undefined and whether SINE RNAs interact with and activate inflammasome components in AD is unknown. This proposal will test the hypothesis that AD pathology is exacerbated by NLRP3/NLRC4 activation induced by endogenous SINE RNA accumulation. We will test this hypothesis via three specific aims: 1) We will quantitate SINE RNA expression and inflammasome activation and map their cellular origins in the 5xFAD model of AD; 2) We will determine the cellular mechanisms of SINE RNA- induced inflammasome activation in brain microglia, whether SINE RNA compromises Aβ phagocytosis by microglia, and whether inflammasome inhibitors improve Aβ phagocytosis; and 3) We will test the effects of individual and dual inflammasome inhibitors on Aβ clearance as well as cognitive and behavioral deficits in the 5xFAD model. Collectively, these thematically related but independent aims will shed light on the contribution of SINE RNAs-induced inflammasome activation in AD. This project is responsive to RFA-AG-22-021 as it will (a) define the functional roles and causal relationships between SINE RNAs and neuroinflammation; (b) define the mechanisms underpinning innate and immune responses to SINE RNAs; and (c) test therapeutic interventions interfering with SINE RNA-mediated molecular pathways. These studies will provide a deeper mechanistic understanding of the role of TEs that can serve as a foundation for future translational research.