Modulating microglial function to restore A-beta proteostasis in Alzheimer's Disease

项目总结/摘要 阿尔茨海默病是一种使人衰弱的退行性疾病，没有有效的治疗， 普遍性。开发有效的治疗方法一直受到阻碍，因为潜在的生物学机制 驾驶疾病的发病机制仍然知之甚少。淀粉样前体蛋白异常裂解 (APP)产生聚集形式的神经毒性淀粉样β（Aβ）蛋白一直是研究的焦点。 调查多年。尽管APP突变引起的早发性家族性AD非常罕见， 或加工相关蛋白PSEN 1和PSEN 2证实了Aβ在AD发病机制中的作用， 大多数病例（>95%）没有明确的遗传原因。许多风险相关基因（>26）已被确定， 但它们中的大多数在AD发病机制中的作用仍然知之甚少。小胶质细胞是固有的 免疫细胞介导对Aβ蛋白的持续性神经炎症反应，其特征在于增加 炎性细胞因子产生、突触丧失和神经毒性。许多已确定的风险相关基因 似乎编码在小胶质细胞中表达的蛋白质，并参与吞噬作用和内溶酶体 运输和蛋白水解降解，提高了小胶质细胞的基本异常可能 导致Aβ加工不良和持续性神经炎症，导致神经毒性， AD中的神经变性。 血管紧张素转换酶（ACE）是一个研究非常少的风险相关基因。以前的研究 我们发表的研究结果和强有力的初步数据表明，它在Aβ从大脑中清除中具有重要作用， 并在增强Aβ蛋白的吞噬作用，其内溶酶体运输和蛋白水解降解中起作用。 小胶质细胞该项目概述了三个具体目标：（1）研究ACE在小胶质细胞中的作用 在新的转基因小鼠和AD动物模型中，（2）研究ACE的分子机制， 调节小胶质细胞中的基因表达，并确定其在吞噬作用，内溶酶体运输和 蛋白水解降解和（3）表征ACE在人诱导的小胶质细胞中的功能， 小鼠大脑中研究其在AD模型中的体内反应。 数百万人患有AD，但预防和治疗仍然非常差。我们预计 这些研究集中在AD风险相关基因ACE及其在小胶质细胞Aβ加工中的作用， 鉴定增强Aβ蛋白加工的新信号通路。此外，我们预计， 这些研究可能阐明小胶质细胞的机制，可用于开发增强Aβ的治疗方法。 蛋白质稳态和减轻AD脑中的神经炎症。

PROJECT SUMMARY / ABSTRACT Alzheimer’s Disease is a debilitating degenerative disease without effective treatment that is increasing in prevalence. Developing effective therapies has been impeded because the underlying biological mechanisms driving disease pathogenesis are still poorly understood. Abnormal cleavage of amyloid precursor protein (APP) that generates aggregating forms of neurotoxic amyloid-beta (Aβ) protein has been a focus of investigation for many years. Although very rare forms of early onset familial AD caused by mutations in APP or processing-associated proteins PSEN1 and PSEN2 substantiate a role for Aβ in the pathogenesis of AD, most cases (>95%) have no definitive genetic cause. Many risk-associated genes (>26) have been identified, but the role of most of them in AD pathogenesis remains very poorly understood. Microglia are resident innate immune cells that mediate persistent neuroinflammatory responses to Aβ protein characterized by increased inflammatory cytokine production, synapse loss and neurotoxicity. Many of the identified risk-associated genes appear to encode proteins that are expressed in microglia and involved in phagocytosis and endolysosomal trafficking and proteolytic degradation, raising the possibility that fundamental abnormalities in microglia may contribute to poor Aβ processing and persistent neuroinflammation that leads to neurotoxicity and neurodegeneration in AD. Angiotensin Converting Enzyme (ACE) is a very poorly studied risk-associated gene. Previous studies published by us and strong preliminary data indicate that it has a significant role in Aβ clearance from the brain and in enhancing Aβ protein phagocytosis, its endolysosomal trafficking and proteolytic degradation in microglia. The project is outlined in three specific aims to: (1) examine the role of ACE specifically in microglia in novel transgenic mice and in an animal model of AD, (2) examine the molecular mechanisms of ACE- regulated gene expression in microglia and determine their role in phagocytosis, endolysosomal trafficking and proteolytic degradation and (3) characterize the function of ACE in human induced microglia engrafted into mice brains to study their response in vivo in a model of AD. Millions of humans are afflicted with AD, yet prevention and treatment remain very poor. We anticipate that these studies focused on the AD risk-associated gene ACE and its role in Aβ processing in microglia will identify novel signaling pathways that enhance Aβ protein processing. Moreover, we anticipate that these studies may elucidate mechanisms in microglia that may be exploited to develop treatments to enhance Aβ proteostasis and mitigate neuroinflammation in the brain in AD.