Role of microglial lysosomes in amyloid-A-beta degradation

小胶质细胞溶酶体在淀粉样蛋白-A-β降解中的作用

• 批准号: 10734289
• 负责人: Frederick R. Maxfield
• 金额: $ 168.47万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10734289
• 关键词: Actins; Adipocytes; Affect; Alzheimer' s Disease; Alzheimer' s disease model; Amyloid; Amyloid beta-Protein; Animals; Antibodies; Area; Atherosclerosis; Binding; Biological Assay; Brain; Cell Culture Techniques; Cells; Confocal Microscopy; Cultured Cells; Data; Deposition; Development; Digestion; Electron Microscopy; Endocytosis; F-Actin; Fluorescence; Genetic study; Goals; Human; Hydrolysis; Immune; Immunoglobulin G; Lipoproteins; Low-Density Lipoproteins; Lysosomes; MFAP1 gene; Macrophage; Measures; Methods; Microglia; Modeling; Mus; Mutant Strains Mice; Mutation; Neuropathy; Optics; PIK3CG gene; Pathway interactions; Phagocytes; Pharmaceutical Preparations; Phosphatidylinositide 3-Kinase Inhibitor; Play; Polymers; Process; Proteins; Proton Pump; Role; Senile Plaques; Signal Pathway; Signal Transduction; Signaling Molecule; Study models; Synapses; TREM2 gene; Testing; Time; Wild Type Mouse; animal tissue; extracellular; genetic testing; in vivo; induced pluripotent stem cell; late endosome; mouse model; multiphoton microscopy; novel; pharmacologic; polymerization; seal; tau Proteins; tau aggregation; tissue culture; treatment effect; uptake; vacuolar H+-ATPase

We have characterized a process used by phagocytic cells to digest objects that are too large to be phagocytosed. We call this process digestive exophagy, and we have demonstrated its role in digestion of large aggregates of lipoproteins in atherosclerosis and also in the digestion of dead adipocytes. We hypothesize that microglia use digestive exophagy to trim and partially degrade β-amyloid. This may be the mechanism by which microglia limit the expansion of β-amyloid plaques. Digestive exophagy involves the formation of a tight seal on the object to be degraded (a lysosomal synapse), secretion of late endosomes and lysosomes (LE/Ly) into the lysosomal synapse, and acidification by V-ATPase proton pumps. We have evidence that primary microglia in culture form lysosomal synapses upon contact with β-amyloid. In Aim 1 we will continue to characterize this. First, we will confirm our preliminary data that microglia create acidified, F-actin-rich contact regions when they interact with β-amyloid and that they secrete lysosomal contents into these areas. We will then quantify time-dependent degradation of amyloid in these compartments. We will determine if anti- Aβ IgG increases digestion of the plaques by microglia. We will also use optical and electron microscopy to examine evidence for digestive exophagy in AD model mice. We have partially characterized the signaling mechanisms required for digestive exophagy by macrophages, and we will use this as a model for studies in microglia. We note that the signaling pathways we described for digestive exophagy overlap signaling pathways implicated in genetic studies of Alzheimer’s disease. In Aim 2 we will explore the effects of some of these mutations on digestive exophagy. These will include Trem2R47H, Dap12-/-, and Trem2-/- mouse microglia. We have shown that pharmacological manipulation of PI3-kinase and Akt as well as other signaling molecules alter digestive exophagy in macrophages, and we will extend our preliminary studies on the effects of these drugs on digestive exophagy of amyloid by microglia. Microglia have been proposed to play a role in the spread of neuropathic fibrils, including tau and undigested Aβ fibrils. LE/Ly secretion, which is an essential component of digestive exophagy, may contribute to the spread of partially digested fragments of tau filaments or Aβ fibrils out of microglial cells, and we will examine this in the third Aim. Specifically, we will determine whether the enhanced LE/Ly secretion when microglia contact β-amyloid leads to enhanced secretion of previously endocytosed fibrils. We will then test the effects of treatments described in Aims 1&2 on endocytosis and digestion of fibrils and their secretion upon contact with amyloid. In our tissue culture studies, we will use primary mouse microglia and human iPSC-derived microglial cells.

我们表征了吞噬细胞用来消化太大的物体而无法实现的过程的过程 吞噬。我们称此过程消化散发性，我们已经证明了它在消化中的作用 脂蛋白在动脉粥样硬化中以及死亡脂肪细胞消化中的大骨聚集体。我们 假设小胶质细胞使用消化疫苗来修剪并部分降解β-淀粉样蛋白。这可能是 小胶质细胞限制β-淀粉样斑块膨胀的机制。消化系统涉及 在要降解的物体上形成紧密的密封（溶酶体突触），内体晚期分泌 和溶酶体（LE/LY）进入溶酶体突触，并通过V-ATPase质子泵酸化。我们有 证据表明，培养物中的原发性小胶质细胞在与β-淀粉样蛋白接触后形成溶酶体突触。在 AIM 1我们将继续对此进行表征。首先，我们将确认小胶质细胞创建的初步数据 酸化的，富含F-肌动蛋白与β-淀粉样蛋白相互作用时，它们是秘密的溶酶体 这些区域的内容。然后，我们将量化淀粉样蛋白的时间依赖性降解 车厢。我们将确定抗AβIgG是否会增加小胶质细胞对斑块的消化。我们将 还使用光学和电子显微镜检查AD模型小鼠中消化散射的证据。 我们已经部分表征了消化销售所需的信号传导机制 巨噬细胞，我们将使用它作为小胶质细胞研究的模型。我们注意到信号通路 我们描述了用于在遗传研究中实施的消化散射重叠信号通路 阿尔茨海默氏病。在AIM 2中，我们将探讨其中一些突变对消化散射的影响。 这些将包括TREM2R47H，DAP12 - / - 和TREM2 - / - 小鼠小胶质细胞。我们已经证明了药理学 PI3-激酶和AKT以及其他信号分子的操纵改变了消化源 巨噬细胞，我们将扩大有关这些药物对消化影响的影响的初步研究 小胶质细胞对淀粉样蛋白的散热。 已经提出小胶质细胞在神经性原纤维的传播中发挥作用，包括tau和 不满意的Aβ原纤维。 Le/ly分泌是消化疫苗的重要组成部分，可能 有助于从小胶质细胞中的部分消化片段或Aβ纤维的部分消化片段的扩散， 我们将在第三个目标中对此进行研究。具体来说，我们将确定是否增强/ly/ly 分泌小胶质细胞接触β-淀粉样蛋白会导致先前内吞纤维的分泌增强。 然后，我们将测试目标1和2中描述的治疗方法对原尾吞噬和消化和消化的影响 他们与淀粉样蛋白接触时的分泌。在我们的组织培养研究中，我们将使用原代小鼠小胶质细胞 和人IPSC衍生的小胶质细胞。