Macrophage-lipoprotein Interactions

巨噬细胞-脂蛋白相互作用

• 批准号: 10117551
• 负责人: Frederick R. Maxfield
• 金额: $ 36.42万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2022-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10117551
• 关键词: 1-Phosphatidylinositol 3-Kinase; AKT1 gene; Actins; Adipocytes; Affect; Alzheimer' s Disease; Amyloid; Amyloid beta-Protein; Area; Arterial Fatty Streak; Atherosclerosis; Biochemical; Biological; Biological Assay; Biotin; Bone Marrow; Cell Culture Techniques; Cells; DNA Sequence Alteration; Data; Dementia; Dendritic Cells; Deposition; Development; Dextrans; Digestion; Dyes; Enzymes; F-Actin; Fluorescein-5-isothiocyanate; Fluorescence; Frontotemporal Dementia; Genetic; Hydrolysis; Image; Incubated; Individual; Inflammatory; Knockout Mice; Label; Laboratories; Link; Lipoproteins; Low-Density Lipoproteins; Lysosomes; Macrophage Activation; Macrophage Colony-Stimulating Factor; Measures; Methods; Microglia; Modeling; Molecular; Mouse Strains; Mus; Mutant Strains Mice; Mutation; Nerve Degeneration; Neurodegenerative Disorders; PGRN gene; Pathway interactions; Phagocytes; Predisposition; Process; Proteins; Reporting; Risk Factors; Role; SYK gene; Senile Plaques; Signal Pathway; Signal Transduction; Signaling Molecule; Streptavidin; Synapses; TLR4 gene; TREM2 gene; TYROBP gene; Time; Vendor; Wild Type Mouse; age related; extracellular; insight; macrophage; mutant; novel; parent grant; polymerization; public health relevance; sex

Abstract We have characterized a novel process carried out by phagocytes that we have called "digestive exophagy". We have shown that macrophages and dendritic cells create extracellular, acidified lysosomal compartments to digest large objects such as aggregates of LDL or dead adipocytes that are too large to be phagocytosed. We have found that genetic mutations associated with neurodegenerative disorders (e.g., frontotemporal dementia and Alzheimer's disease) also affect the digestive exophagy of aggregated LDL (agLDL), such as that found in atherosclerotic plaques. This is consistent with similar cellular mechanisms being involved in both cases. In this supplement, we propose to apply the methods we have developed to study digestive exophagy of amyloid Aβ by microglia. We will also continue to examine mutants identified in neurodegeneration studies for their effect on digestion of agLDL by macrophages. We have reported that macrophages lacking progranulin (GRN) have greatly increased exophagy of aggregated LDL. Mutations or reduced expression of GRN are linked to AD as well as frontotemporal dementia. TLR4 and other signaling molecules are required for digestive exophagy, and these same signaling pathways are modulated by TREM2, a protein that is highly expressed in microglia. Mutations in TREM2 are strongly linked to increased susceptibility for AD. Preliminary studies have shown that microglia create similar acidic compartments upon contact with large aggregates of fAβ, and they secrete lysosomal contents into them. In Aim 1 we will characterize the mechanism by which microglia degrade large aggregates of fAβ. We expect to confirm preliminary observations of lysosome secretion and compartment acidification. We will use fluorescently labeled fAβ to observe and quantify the degradation of fAβ deposits. These studies will be carried out using primary mouse microglia. In Aim 2 we will analyze signaling mechanisms that regulate lysosome secretion and degradation of amyloid Aβ by microglia. Interestingly, preliminary data have shown that lack of Dap12, an effector of TREM2 signaling, in bone marrow macrophages leads to a large increase in lysosome secretion upon contact with LDL aggregates or Aβ deposits. Similar studies will be carried out in microglia from wild type and knockout mice contacting Aβ deposits to determine if there is a role for GRN, Trem2, Dap12, Tlr4 and other proteins. As illustrated by the Dap12 results, proteins identified in the Alzheimer's studies may reveal new signaling in macrophages to be studied in the parent grant.

抽象的 我们描述了吞噬细胞执行的一种新过程，我们称之为“消化” 外噬”。我们已经证明巨噬细胞和树突状细胞产生细胞外的酸化溶酶体 用于消化大物体的隔室，例如太大而无法消化的低密度脂蛋白聚集体或死亡脂肪细胞 被吞噬。我们发现与神经退行性疾病相关的基因突变（例如， 额颞叶痴呆和阿尔茨海默氏病）也会影响聚集的低密度脂蛋白的消化外食 (agLDL)，例如在动脉粥样硬化斑块中发现的。这与类似的细胞机制一致 均涉及两起案件。在本补充中，我们建议应用我们开发的方法 研究小胶质细胞对淀粉样蛋白 Aβ 的消化外噬。我们还将继续检查中发现的突变体 神经变性研究对巨噬细胞消化 agLDL 的影响。我们曾报道过 缺乏颗粒体蛋白前体（GRN）的巨噬细胞对聚集的低密度脂蛋白的吞噬能力大大增加。突变或 GRN 表达减少与 AD 和额颞叶痴呆有关。 TLR4 和其他信号传导 消化外食需要分子，这些相同的信号传导途径受到以下因素的调节 TREM2，一种在小胶质细胞中高度表达的蛋白质。 TREM2 的突变与增加 AD 的易感性。 初步研究表明，小胶质细胞在与物质接触时会产生类似的酸性区室。 fAβ 的大聚集体，并向其中分泌溶酶体内容物。在目标 1 中，我们将描述 小胶质细胞降解大聚集的 fAβ 的机制。我们预计将初步确认 溶酶体分泌和室酸化的观察。我们将使用荧光标记的 fAβ 观察并量化 fAβ 沉积物的降解。这些研究将使用初级 小鼠小胶质细胞。在目标 2 中，我们将分析调节溶酶体分泌的信号机制 以及小胶质细胞对 Aβ 淀粉样蛋白的降解。有趣的是，初步数据表明，缺乏 Dap12 是骨髓巨噬细胞中 TREM2 信号传导的效应子，导致溶酶体大量增加 与 LDL 聚集体或 Aβ 沉积物接触后分泌。类似的研究将在小胶质细胞中进行 来自接触 Aβ 沉积物的野生型和敲除小鼠，以确定 GRN、Trem2、 Dap12、Tlr4 等蛋白质。如 Dap12 结果所示，在阿尔茨海默病中鉴定出的蛋白质 研究可能会揭示巨噬细胞中的新信号传导，需要在母基金中进行研究。