Polarity determinants in endolysosomal trafficking and proteostasis: Implications for Alzheimer's disease pathogenesis

内溶酶体运输和蛋白质稳态中的极性决定因素：对阿尔茨海默病发病机制的影响

• 批准号: 9912086
• 负责人: Huaye Zhang
• 金额: $ 19.88万
• 依托单位: RBHS-ROBERT WOOD JOHNSON MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-04-15 至 2023-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9912086
• 关键词: Abeta clearance; Aging; Alzheimer' s Disease; Alzheimer' s disease brain; Alzheimer' s disease risk; Amyloid beta-Protein; Amyloid beta-Protein Precursor; Autophagocytosis; Autophagosome; Axon; Biochemical; Cell Polarity; Characteristics; Color; Complement; Complex; Data; Defect; Dendrites; Disease Progression; Distal; Epithelial; Epithelium; Fluorescent Probes; Frequencies; Generations; Hippocampus (Brain); Human; Image; Knockout Mice; Knowledge; Laboratories; Lead; Light; Link; Lysosomes; Malignant Neoplasms; Measures; Molecular; Nerve Degeneration; Neurons; Pathogenesis; Pathogenicity; Pathway interactions; Peptides; Permeability; Process; Prosencephalon; Proteins; Research; Risk Factors; Role; Signal Transduction; Synaptosomes; Testing; Time; Vacuole; Western Blotting; abeta accumulation; age related; aging brain; beta secretase; beta-site APP cleaving enzyme 1; conditional knockout; confocal imaging; gamma secretase; imaging study; in vivo; middle age; neuron development; novel; novel therapeutics; optogenetics; presenilin-1; proteostasis; stem; stem cell division; trafficking

Project Summary The vast majority of Alzheimer’s disease (AD) is sporadic, with aging being the biggest risk factor. Yet age-related changes within neurons that can drive the AD pathogenic process remain elusive. Intriguingly, there is an intricate link between the aging process and cell polarity. Dysregulation of polarity is observed in many cellular contexts during aging, such as increased permeability of epithelial barriers, defective asymmetric division of stem cells and increased frequency of cancer. However, whether brain aging and Alzheimer’s disease result from polarity dysregulation is unknown. Research in our laboratory has focused on the partitioning defective (Par) polarity proteins in neuronal development and degeneration. Interestingly, our recent studies point to a key role for Par3 in the pathogenesis of AD. AD is characterized by plaques composed of β-amyloid (Aβ), which is derived from amyloid precursor protein (APP) through cleavage by β- and γ-secretases. The rate-limiting step of Aβ generation is the convergence between APP and its β-secretase BACE1. We found Par3 expression is significantly reduced by middle-age, and loss of Par3 is common in human AD brains. In addition, Par3 depletion causes a significant increase in APP and BACE1 convergence. Unexpectedly, we found Aβ accumulates intracellularly in the absence of Par3. Further studies suggest this is caused by defective autophagosome clearance. Remarkably, accumulation of autophagosomes and other autophagic vacuoles is also characteristic of the AD brain. Thus, these exciting data have led to our hypothesis that loss of Par3 in the aging brain promotes AD progression by targeting both APP/BACE1 convergence and autophagy. Dysregulation of these processes will lead to intracellular Aβ accumulation, which is highly toxic to neurons. We will test our hypothesis through two aims. In Aim 1, we will elucidate the mechanism by which Par3 regulates APP and BACE1 convergence and intracellular Aβ accumulation. In Aim 2, we will examine the mechanism by which Par3 regulates autophagy and lysosome functions. We will use a combination of BiFC, optogenetic manipulation of Par protein activity, as well as in vivo analysis in forebrain- specific Par3 conditional knockout mice. Together, our proposed studies will establish the molecular mechanisms by which Par polarity proteins are involved in AD pathogenesis. The results will shed light on the mechanism of sporadic AD in which aging is the major risk factor and polarity dysregulation may be the common feature.

项目摘要 阿尔茨海默氏病（AD）的绝大多数都是零星的，老龄化是最大的危险因素。然而 神经元内与年龄相关的变化可以驱动AD致病过程仍然难以捉摸。有趣的是， 老化过程与细胞极性之间存在复杂的联系。在 衰老期间的许多细胞环境，例如上皮屏障的渗透性增加，不对称的不对称性 干细胞的分裂和癌症的频率增加。但是，是否大脑衰老和阿尔茨海默氏症 极性失调引起的疾病尚不清楚。我们实验室的研究集中于 在神经元发育和变性中分配缺陷（PAR）极性蛋白。有趣的是，我们的 最近的研究表明，PAR3在AD发病机理中的关键作用。广告以斑块为特征 由β-淀粉样蛋白（Aβ）组成，该淀粉样蛋白（Aβ）通过β-裂解源自淀粉样蛋白前体蛋白（APP） 和γ-分泌酶。 Aβ生成的速率限制步骤是APP与其β-分泌酶之间的收敛性 Bace1。我们发现PAR3表达通过中年大大降低，并且PAR3的丢失在 人类广告大脑。此外，PAR3降低会导致APP和BACE1收敛的显着增加。 出乎意料的是，我们发现在没有PAR3的情况下，Aβ会在细胞内积累。进一步的研究表明这是 由自噬体间隙缺陷引起。值得注意的是，自噬体和其他 自噬液泡也是广告大脑的特征。那就是这些令人兴奋的数据导致了我们的 假设衰老大脑中PAR3的丧失通过靶向App/Bace1来促进AD的进展 收敛和自噬。这些过程的失调将导致细胞内Aβ的积累， 对神经元有剧毒。我们将通过两个目标检验我们的假设。在AIM 1中，我们将阐明 PAR3调节APP和BACE1收敛和细胞内Aβ积累的机制。目标 2，我们将检查PAR3调节自噬和溶酶体功能的机制。我们将使用一个 BIFC的结合，PAR蛋白活性的光遗传操作以及前脑 - 体内分析 特定的PAR3条件敲除小鼠。我们提出的研究将共同​​建立分子 Parter蛋白参与AD发病机理的机制。结果将使 零星AD的机制是衰老是主要危险因素，极性失调可能是 共同特征。