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

基本信息

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
项目类别：
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&apos s Disease Alzheimer&apos s disease brain Alzheimer&apos 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

项目摘要

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.

项目概要神经炎症是阿尔茨海默病（AD）进展的主要因素。其特点是胆固醇和脂质代谢改变。炎症反应共定位于通常称为脂筏的有序膜微域中。激活，脂筏驻留和招募的分子组装并启动信号级联，导致我们已经确定 apoA-I 结合蛋白（AIBP，由 APOA1BP 基因编码）作为关键。细胞胆固醇代谢的调节剂，可以选择性地靶向炎症细胞中的脂筏（炎症）通过与 TLR4 结合，而细胞外 AIBP 调节血浆中的胆固醇消耗。膜并控制脂筏，细胞内 AIBP 定位于线粒体，促进线粒体自噬并帮助维持正常线粒体功能并控制氧化应激。 Apoa1bp-/- APP/PS1 小鼠表现出更多。 β 淀粉样蛋白 (Aβ) 斑块，一种加剧功能失调的小胶质细胞表型，并显示细胞死亡增加与 APP/PS1 小鼠相比，AIBP 缺陷的小胶质细胞中的线粒体形态发生了扭曲。特征性的超支化和杯状形状，通常在 AAV 介导的氧化应激后出现。 Apoa1bp-/- APP/PS1 小鼠大脑中分泌型 AIBP 的表达恢复了体内平衡该提案的目的是描述 AIBP 保护作用的机制。在 AD 大脑中，重点关注小胶质细胞脂筏和线粒体功能障碍，具体来说，在目标 1 中，我们。提议检验细胞外 AIBP 逆转小胶质细胞中的病理筏脂质以减少的假设我们已经鉴定出 TLR4- 可以抑制 AD 小鼠模型中的神经炎症并防止神经变性。 AIBP 分子中的结合域，并证明 AIBP(ΔTLR4) 变体不结合 TLR4，无法逆转脂筏的改变，我们计划使用 AAV 来恢复分泌变体的表达。 Apoa1bp-/- APP/PS1 小鼠大脑中的 AIBP，预计 AIBP(wt) 而不是 AIBP(ΔTLR4) 会减轻我们还期望神经炎症、Aβ 斑块负担和磷酸 tau 积累得到改善。在目标 2 中，我们将测试细胞内 AIBP 保护线粒体的假设。 AD小鼠模型中线粒体的动力学和功能是显示浓度的主要位点。细胞内 AIBP，初步研究表明 AIBP 参与线粒体功能的控制，线粒体自噬和氧化应激的方法包括跨尺度的相关光学显微镜和 3D EM，利用串行块面扫描 EM 和 EM 断层扫描技术的进步以及相关测量为了测试所提出的机制与人类 AD 的相关性，我们将在目标 3 中进行生物能量学研究。描述尸检和脑活检中与 AIBP 相关的筏脂质和线粒体功能障碍标记物 AD 科目的部分。