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.

摘要