Metabolite profiling to identify AD-relevant pathways affected by apoe variants

描述（由申请人提供）：载脂蛋白E（APOE）4基因携带者患阿尔茨海默病（AD）的风险显著增加。虽然已经提出了许多理论，但这种关联的原因仍然不清楚。最广泛接受的观点是，在APOE <$4携带者中观察到的加速AD病理学是由于apoE 4蛋白从大脑中清除A <$的能力降低。然而，拥有APOE <$4基因也会导致许多与A <$清除无关的其他神经功能缺陷，包括神经元结构的改变，内嗅皮层（EC）层变薄和中风后的预后较差，这表明可能有其他机制参与这一过程。为了更全面地了解不同apoE亚型的表达如何影响大脑，以及这如何影响AD和其他年龄相关神经系统疾病的风险，我们建议使用质谱法来鉴定其水平受apoE亚型表达变化影响的脂质和小分子。为了实现这一点，我们将首先从无病理EC和初级视觉皮层（PVC）组织中提取脂质，小分子和蛋白质，这些组织来自14个月大的小鼠和表达不同apoE亚型的19-55岁的尸检个体。然后将这些提取物的脂质和小分子组分用于进行靶向脂质组学和非靶向代谢组学，然后进行生物信息学分析和各种验证实验，以确定受大脑中替代apoE亚型表达影响的特定脂质，小分子和代谢途径。到目前为止，初步研究已经发现了能量代谢途径和几个重要的脂质亚类的显着变化，证明了这些技术的力量，发现以前未知的亚型特异性的apoE在大脑中的影响。我们期望本文提出的完整研究将揭示脂质和小分子水平的进一步apoE亚型特异性变化，并将导致对apoE 4如何影响AD病理学的更深入了解，可能导致AD和受apoE 4表达影响的其他神经系统疾病的新治疗策略。

DESCRIPTION (provided by applicant): Carriers of the apolipoprotein E (APOE) ¿4 gene are at significantly increased risk for developing Alzheimer's disease (AD). Although numerous theories have been proposed, the cause of this association remains unclear. The most widely accepted view is that the accelerated AD pathology observed in APOE ¿4 carriers is due to a decreased ability of the apoE4 protein to clear A¿ from the brain. However, possession of the APOE ¿4 gene also results in a number of other neurological deficits unrelated to A¿ clearance, including alterations in neuronal structure, thinner entorhinal cortex (EC) layers and poorer outcomes after stroke, suggesting that there may be other mechanisms involved in this process. In order to gain a more comprehensive understanding of the how the expression of different apoE isoforms affects the brain and how this may impact the risk of developing AD and other age-related neurological illnesses, we propose to use mass spectrometry to identify lipids and small-molecules whose levels are affected by changes in apoE isoform expression. To accomplish this, we will first extract lipids, small-molecules and proteins from pathology-free EC and primary visual cortex (PVC) tissues obtained from 14-month old mice and postmortem 19-55 year old individuals expressing differing apoE isoforms. The lipid and small-molecule fractions from these extracts will then be used to perform targeted lipidomics and untargeted metabolomics, followed by bioinformatic analysis and a variety of validation experiments, in order to determine the specific lipids, small-molecules and metabolic pathways that are affected by alternative apoE isoform expression in the brain. Thus far, preliminary studies have uncovered significant changes in energy metabolism pathways and several important lipid subclasses, demonstrating the power of these techniques for discovering previously unknown isoform-specific effects of apoE in the brain. We expect that the full study proposed herein will uncover further apoE isoform-specific changes in lipid and small-molecule levels and will lead to a greater understanding of how apoE4 influences AD pathology, potentially leading to new therapeutic strategies for AD and other neurological illnesses influenced by apoE4 expression.