Modulation of Amyloid-Beta Aggregation in the Endosomal/Lysosomal Pathway

内体/溶酶体途径中淀粉样蛋白-β 聚集的调节

• 批准号: 8453848
• 负责人: Scott L Crick
• 金额: $ 4.71万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8453848
• 关键词: Alzheimer' s Disease; American; Amyloid; Appearance; Atomic Force Microscopy; Biochemical; Biological; Biological Assay; Brain; Cathepsins B; Cells; Cellular biology; Cerebrospinal Fluid; Characteristics; Chemicals; Data; Deposition; Development; Disease; Endocytosis; Endosomes; Energy Transfer; Environment; Environmental Risk Factor; Equilibrium; Extracellular Space; Family; Fluorescence; Fluorescence Spectroscopy; Fractionation; Genetic; Goals; In Vitro; Intercellular Fluid; Lead; Location; Lysosomes; Maintenance; Measurement; Measures; Methods; Microscopic; Microscopy; Mutation; Nerve Degeneration; Neurons; Pathogenesis; Pathway interactions; Peptide Hydrolases; Peptides; Phase; Play; Presenile Alzheimer Dementia; Proteins; Quality Control; Role; Route; Senile Plaques; Solutions; Specificity; Staging; Testing; Time; Toxic effect; Vesicle; Work; abeta accumulation; amyloid formation; amyloid pathology; brain tissue; extracellular; in vivo; insight; late endosome; mutant; novel; prion-like; protein aggregate; public health relevance; research study; tool; trafficking; uptake

DESCRIPTION (provided by applicant): The goal of this project is to investigate a potential mechanism by which amyloid-¿ peptides (A¿) form aggregates in the brain. This is directly relevant to the pathogenesis of Alzheimer's disease (AD). In vitro studies have shown that A¿ forms aggregates only at concentrations that are more than one thousand times higher than those measured in cerebrospinal fluid and in brain tissue. Even so, A¿ plaque formation is characteristic for AD and genetic evidence demonstrates that mutations that increase A¿ aggregation propensity lead to early onset AD. This apparent contradiction suggests that there must either be: 1) high local concentrations of A¿ somewhere in the brain, or 2) cellular and/or biochemical mechanisms which lower the concentration required for A¿ to aggregate. Growing evidence suggests that A¿ can accumulate in intraneuronal vesicles well before the first appearance of amyloid plaques. Our preliminary data suggest that A¿ can be endocytosed and trafficked through the endo/lysosomal pathway. Moreover, we have found that A¿ is concentrated in late endo/lysosomes to levels that would support A¿ aggregation. This occurs even when low, physiologically relevant concentrations of A¿ are added to the outside of the cell. Also, we know that certain features of the endo/lysosomal environment, such as low pH, favor A¿ aggregation. This makes the endo/lysosomal pathway particularly attractive for nascent A¿ aggregate formation in vivo. The hypothesis to be tested in this work is that the earliest stages of A¿ aggregation in vivo occur within neural cells during endo/lysosome maturation. In this proposal, we will investigate A¿ uptake from the extracellular space and the effect of trafficking along the endo/lysosomal pathway on its aggregation state. We will use modern fluorescence spectroscopic and microscopic methods to develop a detailed time course of the uptake, trafficking, and aggregation of A¿ along the endo/lysosomal pathway. These experiments will be combined with modern cell biology tools to interrogate how specific environmental factors of the endo/lysosomal pathway contribute to the aggregation of A¿. We speculate that endocytosis and trafficking of A¿ along the endo/lysosomal pathway represents a normal pathway for quality control and maintenance of extracellular A¿ levels. However, characteristics of the endo/lysosomal environment, such as low pH and locally high protein concentrations, favor A¿ aggregation. It is quite possible that the balance between A¿ aggregation and degradation along the endo/lysosomal pathway is a critical determinant in AD pathogenesis.

描述（由申请人提供）：该项目的目标是研究淀粉样蛋白-肽(a)在大脑中形成聚集体的潜在机制。这与阿尔茨海默病（AD）的发病机制直接相关。体外研究表明，只有在比脑脊液和脑组织中测量的浓度高1000倍以上的浓度下，A¿才能形成聚集体。即便如此，A -斑块形成是AD的特征，遗传证据表明，增加A -斑块聚集倾向的突变会导致AD的早期发病。这一明显的矛盾表明，要么存在：(1)大脑某处局部高浓度的A¿，要么存在(2)降低A¿聚集所需浓度的细胞和/或生化机制。越来越多的证据表明，早在淀粉样斑块首次出现之前，A¿就可以在神经元内的囊泡中积累。我们的初步数据表明，A¿可以通过内吞/溶酶体途径被内吞和运输。此外，我们还发现A¿在末端/溶酶体中集中到支持A¿聚集的水平。即使在细胞外添加低的、与生理相关的A¿浓度时，也会发生这种情况。此外，我们知道内切酶/溶酶体环境的某些特征，如低pH值，有利于A¿聚集。这使得内切酶/溶酶体途径对体内新生的A¿聚集形成特别有吸引力。在这项工作中要测试的假设是，体内A¿聚集的最早阶段发生在神经细胞内的内切酶/溶酶体成熟期间。在这一提议中，我们将研究从细胞外空间摄取A¿以及沿内切酶/溶酶体途径运输对其聚集状态的影响。我们将使用现代荧光光谱和显微方法来开发a¿的摄取，运输和聚集的详细时间过程沿着内切/溶酶体途径。这些实验将与现代细胞生物学工具相结合，探讨内切酶/溶酶体途径的特定环境因素如何促进A¿的聚集。我们推测，A¿的内吞作用和运输沿内切/溶酶体途径代表了质量控制和维持细胞外A¿水平的正常途径。然而，内端/溶酶体环境的特点，如低pH值和局部高蛋白质浓度，有利于A¿聚集。很有可能A¿聚集和降解之间的平衡沿着内切酶/溶酶体途径是AD发病机制的关键决定因素。