PHF15, a potential repressor of inflammation in the brain and its relevance to Alzheimer's disease

摘要 虽然阿尔茨海默病(AD)的遗传风险因素已经被确定，但大约90%的 患者为散发性病例。因此，在这个提议中，我们试图了解分子机制 建立散发性阿尔茨海默病病例的背后。最近，我们发现了一种可能的表观遗传学 调节因子PhD Finger 15(PHD15)是小胶质细胞炎症调控基因的转录抑制因子。 事实上，在小鼠小胶质细胞中敲除Phf15足以增加促炎介质和 抗病毒基因，包括淀粉样前体蛋白(APP)和补体因子，在缺乏 任何刺激。因为PHF15在人和小鼠小胶质细胞中的mRNA表达增加 健康衰老，我们假设PHF15在表观遗传学上抑制AGE诱导的小胶质细胞炎症和 未能上调PHF15会导致神经炎症和认知能力下降。为了检验我们的假设， 我们将通过质谱分析鉴定含有PHF15的蛋白质复合体的成员 我们已经建立的小胶质细胞系。在使用生化分析确认蛋白质结合后，我们将 通过建立功能增减细胞系来进行功能分析，以验证所识别的 复杂的蛋白质与PHF15合作抑制炎症。除了分离PHF15蛋白 复杂，我们还将尝试识别阻止PHF15 mRNA上调的非遗传因素，使用两者 体内模型和体外模型。根据我们的初步数据，我们将重点关注病毒感染和高脂饮食对老年人的影响 体内实验，以及氧化应激和感染模拟物(Toll样受体和Toll样受体的配体 炎性小体)进行体外实验。总体而言，该提案的目标是确定分子 PHF15抑制小胶质细胞炎症的机制及识别非遗传因素 阻止PHF15表达上调。这些结果可能有助于我们更好地理解 疾病。

Abstract While genetic risk factors for Alzheimer’s disease (AD) have been identified, around ninety percent of patients are sporadic cases. Therefore, in this proposal, we seek to understand the molecular mechanisms behind the establishment of sporadic cases of AD. Recently, we have found that a putative epigenetic regulator, PHD finger 15 (PHD15), is a transcriptional repressor of genes regulating inflammation in microglia. Indeed, knockout of Phf15 in mouse microglial cells was sufficient to increase pro-inflammatory mediators and anti-viral genes, of note, including amyloid precursor protein (APP) and complement factors, in the absence of any stimuli. Because the mRNA expression of PHF15 in human and mouse microglia is increased upon healthy aging, we hypothesize that PHF15 epigenetically represses age-induced inflammation in microglia and that failure to up-regulate PHF15 results in neuroinflammation and cognitive decline. To test our hypothesis, we will identify members of the protein complex containing PHF15 by mass-spectrometry using a human microglial cell line that we have established. After confirming protein binding using biochemical assays, we will perform functional assays by establishing gain- and loss-of-function cell lines to validate whether the identified complex proteins cooperate with PHF15 to repress inflammation. In addition to isolating the PHF15 protein complex, we will also try to identify non-genetic factors that prevent PHF15 mRNA up-regulation using both in vivo and in vitro models. Based on our preliminary data, we will focus on virus infection and high-fat diet for the in vivo experiments, as well as oxidative stress and infection mimics (ligands for toll-like receptors and inflammasomes) for the in vitro experiments. Overall, the goals of this proposal are to determine the molecular mechanism behind how PHF15 represses inflammation in microglia and to identify non-genetic factors that prevent up-regulation of PHF15 expression. These results may help us to better understand the causes of sporadic cases of AD and, thus, direct the development of treatment strategies to treat and/or prevent this disease.