Reversing Microglial Inflammarafts and Mitochondrial Dysfunction in Alzheimer's Disease

逆转阿尔茨海默病中的小胶质细胞炎症和线粒体功能障碍

• 批准号: 10607455
• 负责人: Mark H Ellisman
• 金额: $ 78.91万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-12-01 至 2027-11-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10607455
• 关键词: 3-Dimensional; APP-PS1; ATP binding cassette transporter 1; Alzheimer' s Disease; Alzheimer' s disease brain; Alzheimer' s disease model; Amyloid beta-Protein; Apolipoprotein A-I; Architecture; Autopsy; Binding; Binding Proteins; Bioenergetics; Biological Assay; Biopsy; Brain; Cell Death; Cell Survival; Cell membrane; Cells; Characteristics; Cholesterol; Cholesterol Homeostasis; Chronic; Development; Disease associated microglia; Electron Microscopy; Face; Flow Cytometry; Genes; Genus Hippocampus; Goals; Hippocampus; Human; Inflammation; Inflammatory; Inflammatory Response; Knock-out; Knockout Mice; Learning; Light; Measures; Mediating; Membrane Microdomains; Memory; Methods; Microglia; Microscopic; Mitochondria; Morphology; Mus; Nerve Degeneration; Oxidative Stress; Pathologic; Phenotype; Physiological; Play; Proteins; Role; Scanning Electron Microscopy; Senile Plaques; Shapes; Signal Transduction; Site; Slice; Study models; TLR4 gene; Testing; Therapeutic; Transgenic Mice; Variant; abeta accumulation; cholesterol transporters; extracellular; human subject; improved; light microscopy; lipid metabolism; mitochondrial dysfunction; mouse model; neuroinflammation; neuron loss; novel; novel therapeutic intervention; protective effect; receptor; recruit; scaffold; tau-1; tomography

Project Summary Neuroinflammation is a major factor in the progression of Alzheimer's disease (AD). Inflammatory brain microglia are characterized by altered cholesterol and lipid metabolism. Cholesterol and many receptors governing inflammatory responses colocalize in the ordered membrane microdomains often designated as lipid rafts. Upon activation, lipid raft resident and recruited molecules assemble and initiate signaling cascades leading to inflammation. We have identified the apoA-I binding protein (AIBP, encoded by the APOA1BP gene) as a key regulator of cellular cholesterol metabolism, which can selectively target lipid rafts in inflammatory cells (inflammarafts) via its binding to TLR4. While extracellular AIBP regulates cholesterol depletion from the plasma membrane and controls lipid rafts, intracellular AIBP localizes to mitochondria, facilitates mitophagy and helps maintain normal mitochondrial function and control oxidative stress. Apoa1bp-/- APP/PS1 mice present more amyloid beta (Aβ) plaques, an exacerbated dysfunctional microglia phenotype and show increases in cell death when compared to APP/PS1 mice. Mitochondria in AIBP-deficient microglia are morphologically distorted, with a characteristic hyper-branched and cupped shape, typically seen following oxidative stress. The AAV-mediated expression of a secreted form of AIBP in the brain of Apoa1bp-/- APP/PS1 mice restored the homeostatic microglia morphology. The goal of this proposal is to delineate mechanisms governing protective effects of AIBP in the AD brain, focusing on microglial lipid rafts and on mitochondrial dysfunction. Specifically, in Aim 1 we propose to test the hypothesis that extracellular AIBP reverses pathological lipid rafts in microglia to reduce neuroinflammation and protect against neurodegeneration in a mouse model of AD. We have identified a TLR4- binding domain in the AIBP molecule and demonstrated that an AIBP(ΔTLR4) variant, which does not bind TLR4, cannot reverse lipid raft alterations. Using AAV delivery, we plan to restore expression of secreted variants of AIBP in the brain of Apoa1bp-/- APP/PS1 mice and expect that AIBP(wt) but not AIBP(ΔTLR4) will lessen neuroinflammation, the Aβ plaque burden and accumulation of phospho-tau. We also expect improvements in memory and learning. In Aim 2, we will be testing the hypothesis that intracellular AIBP protects mitochondrial dynamics and function in a mouse model of AD. Mitochondria are the major sites displaying concentration of intracellular AIBP, and preliminary studies suggest AIBP involvement in control of mitochondrial function, mitophagy and oxidative stress. Methods will include correlated light microscopy and 3D EM across scales, leveraging advances in serial blockface scanning EM and EM tomography, along with correlated measures of bioenergetics by Seahorse. To test relevance of the proposed mechanisms to human AD, in Aim 3 we will characterize AIBP-related markers of lipid rafts and mitochondrial dysfunction in postmortem and biopsy brain sections from AD subjects.

项目摘要 神经炎症是阿尔茨海默氏病（AD）进展的主要因素。炎症性脑小胶质细胞 以改变胆固醇和脂质代谢为特征。胆固醇和许多管理的受体 炎症反应在有序的膜微区域中共定位，通常被指定为脂质筏。之上 激活，脂质筏居民和招募的分子组装并启动信号传导级联反应导致 炎。我们已经将ApoA-I结合蛋白（AIBP，由apoA1bp基因编码）确定为键 细胞胆固醇代谢的调节剂，可以选择性地靶向炎性细胞中的脂质筏 （炎症）通过其与TLR4的结合。而细胞外AIBP调节血浆中的胆固醇耗竭 膜和控制脂质筏，细胞内AIBP定位于线粒体，促进线粒体并有助于帮助 保持正常的线粒体功能和对照氧化物应激。 apoa1bp - / - app/ps1小鼠出现更多 淀粉样β（Aβ）斑块，一种恶化的功能障碍的小胶质细胞表型并显示出细胞死亡的增加 与APP/PS1小鼠相比。 AIBP缺陷小胶质细胞中的线粒体在形态上扭曲，并具有 特征性的超支线和拔出形状，通常在氧化应激之后看到。 AAV介导的 apoa1bp-/ - app/ps1小鼠的大脑中AIBP的分泌形式的表达恢复 小胶质细胞形态。该提案的目的是描述有关AIBP受保护效果的机制 在AD大脑中，专注于小胶质脂质筏和线粒体功能障碍。具体来说，在目标1中我们 提议测试细胞外AIBP逆转小胶质细胞的病理脂质筏以减少的假设 神经炎症并预防AD小鼠模型中的神经变性。我们已经确定了TLR4- AIBP分子中的结合结构域，并证明AIBP（ΔTLR4）变体不结合TLR4， 无法逆转脂质筏的改变。使用AAV交付，我们计划恢复分泌变体的表达 apoA1bp - / - app/ps1小鼠大脑中的AIBP，并期望AIBP（WT）而不是AIBP（ΔTLR4）会减少 神经炎症，AβPlaqueBurnen和磷酸-TAU的积累。我们还希望改善 记忆和学习。在AIM 2中，我们将测试细胞内AIBP保护线粒体的假设 AD鼠标模型中的动力学和功能。线粒体是显示浓度的主要位置 细胞内AIBP和初步研究表明AIBP参与线粒体功能的控制， 线粒体和氧化应激。方法将包括相关的光学显微镜和跨尺度的3D EM， 利用串行区块扫描EM和EM层析成像的进步，以及相关的措施 Seahorse的生物能学。为了测试拟议机制与人类AD的相关性，在AIM 3中，我们将 表征脂质筏的AIBP相关标记和术后和活检大脑中的线粒体功能障碍 广告主题的部分。