O-GLCNAC HOMEOSTASIS REGULATES MITOCHONDRIAL FUNCTION IN ALZHEIMER'S DISEASE

目前，540万美国人患有阿尔茨海默病(AD)，这是唯一的主要疾病 缺乏好的预防方法、治疗方法或治疗方法的。最近的证据表明，与年龄有关的 线粒体功能受损和活性氧(ROS)生成增加是导致 细胞损伤和阿尔茨海默病进展。本研究的目的是了解O-GlcN酰化对线粒体功能和AD发生发展的影响。O-GlcNAc按加成物分类 一个O-连接的β-N-乙酰-D-氨基葡萄糖部分与核和核的丝氨酸/苏氨酸氨基酸 细胞质蛋白。这种修饰对细胞外信号如激素、营养物质和 并参与调节多种细胞功能，如细胞周期、应激 回复、转录和翻译。负责处理修饰的酶是O-GlcNAc转移酶(OGT)和O-GlcNAcase(OGA)，前者添加修饰，后者去除 修改。重要的是，O-GlcN酰化的改变改变了线粒体的功能。细胞积极维护 O-GlcNAc中的动态平衡水平，细胞会因为环境的变化而改变OGT和OGA的表达，从而调节O-GlcNacylation。我们认为O-GlcN酰化在慢性阻塞性肺疾病中被破坏。 代谢性疾病，加剧线粒体功能的下降。我们已经证明，OGT或OGA的过度表达会导致电子传输链和Krebs蛋白表达的巨大变化 循环蛋白，呼吸作用受损，线粒体形态被破坏。这些数据表明 O-GlcNAc动态平衡的改变会影响线粒体功能，加重AD。在当前 提案中，我们将确定O-GlcN酰化如何调节细胞功能的机制。首先，我们 将确定在阿尔茨海默病小鼠模型或在丢失 OGT。然后我们将确定O-GlcNAc稳态被破坏如何影响电子传输链功能 和代谢基因的表达。我们将讨论OGA抑制剂对改善线粒体的作用 阿尔茨海默病小鼠模型的功能障碍。此外，我们还将探索O-GlcN酰化对线粒体的影响 抗氧化反应。我们的初步数据显示，O-GlcNAc的变化会导致抗氧化的变化 反应和NRF2活性，一个控制抗氧化基因转录的关键转录因子。我们 将确定O-GlcNAc在调节NRF2转录活性和蛋白质中的机制作用 互动。最后，我们将使用AD患者样本来确定使用O-GlcNAc、OGT或OGA的可能性 作为AD生物标志物。这些研究将为O-GlcN酰化如何影响提供新的机制细节 线粒体功能，O-GlcNAc如何影响抗氧化反应，NRF2功能，并将提供新的 阿尔茨海默病临床干预途径。

Currently, 5.4 million Americans are suffering from Alzheimer’s disease (AD), which is the only major disease lacking good prevention methods, treatments, or a cure. Recent evidence suggests that age related impairment of mitochondrial function and increased reactive oxygen species (ROS) production contribute to cellular damage and AD progression. The object of this proposal is to understand the affects of O-GlcNAcylation on mitochondrial function and the development of AD. O-GlcNAc is categorized by the addition of a single O-linked β-N-acetyl-D-glucosamine moiety to serine/threonine amino acids of nuclear and cytoplasmic proteins. This modification is responsive to extracellular signals such hormones, nutrients, and environmental cues and is involved in regulating numerous cellular functions such as the cell cycle, stress response, transcription, and translation. The enzymes responsible for processing the modification are O-GlcNAc transferase (OGT), which adds the modification, and O-GlcNAcase (OGA), which removes the modification. Importantly, changes in O-GlcNAcylation alter mitochondrial function. Cells actively maintain homeostatic levels in O-GlcNAc, and cells will alter the expression of OGT and OGA to modulate O-GlcNAcylation due to changes in the environment. We contend that O-GlcNAcylation is disrupted in chronic metabolic disease, which exacerbates the decline in mitochondrial function. We have demonstrated that over-expression of OGT or OGA causes large changes in protein expression of electron transport chain and Krebs cycle proteins, respiration is impaired, and mitochondrial morphology is disrupted. These data suggest that alterations to O-GlcNAc homeostasis would affect mitochondrial function exacerbating AD. In the current proposal, we will determine the mechanisms as to how O-GlcNAcylation regulates cellular function. First, we will identify changes to the transcriptome, proteome, and O-GlcNAcome in mouse models of AD or after loss of OGT. We will then determine how disrupted O-GlcNAc homeostasis affects electron transport chain function and metabolic gene expression. We will address the effect of OGA inhibitors on ameliorating mitochondrial dysfunction in AD mouse models. Furthermore, we will explore how O-GlcNAcylation influences mitochondrial anti-oxidant response. Our preliminary data shows that alterations in O-GlcNAc induce changes in anti-oxidant response and NRF2 activity, a critical transcription factor controlling the transcription of anti-oxidant genes. We will ascertain the mechanistic role of O-GlcNAc in regulating NRF2 transcriptional activity and protein interactions. Finally, we will use AD patient samples to identify the potential to use of O-GlcNAc, OGT or OGA as AD biomarkers. These studies will provide new mechanistic details into how O-GlcNAcylation affects mitochondrial function, how O-GlcNAc influences anti-oxidant response, NRF2 function, and will provide new pathways for clinical intervention of AD.