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.

项目概要 绝大多数阿尔茨海默病 (AD) 是散发性的，其中衰老是最大的危险因素。 有趣的是，神经元内与年龄相关的变化能够驱动 AD 的致病过程，但这一变化仍然难以捉摸。 在衰老过程和细胞极性失调之间存在着复杂的联系。 衰老过程中的许多细胞环境，例如上皮屏障渗透性增加、不对称缺陷 干细胞分裂和癌症发生率增加然而，大脑衰老和阿尔茨海默氏症是否有关。 极性失调导致的疾病尚不清楚，我们实验室的研究重点是极性失调。 在神经元发育和变性中划分缺陷（Par）极性蛋白。 最近的研究指出 Par3 在 AD 发病机制中的关键作用以斑块为特征。 由β-淀粉样蛋白（Aβ）组成，它是由淀粉样蛋白前体蛋白（APP）经β-淀粉样蛋白裂解而得。 Aβ生成的限速步骤是APP与其β分泌酶之间的收敛。 我们发现，到了中年，Par3 的表达显着减少，Par3 的缺失在中年时期很常见。 此外，Par3 耗尽会导致 APP 和 BACE1 收敛显着增加。 出乎意料的是，我们发现 Aβ 在没有 Par3 的情况下在细胞内积累。进一步的研究表明这是这样的。 由自噬体清除缺陷引起，尤其是自噬体和其他物质的积累。 自噬液泡也是 AD 大脑的特征，因此，这些令人兴奋的数据导致了我们的研究。 假设衰老大脑中 Par3 的缺失会通过靶向 APP/BACE1 促进 AD 进展 这些过程的收敛和自噬失调将导致细胞内 Aβ 积累， 这对神经元有很强的毒性。我们将通过两个目标来检验我们的假设。 Par3 调节 APP 和 BACE1 收敛以及细胞内 Aβ 积累的机制。 2、我们将研究 Par3 调节自噬和溶酶体功能的机制。 BiFC、Par 蛋白活性的光遗传学操作以及前脑体内分析的结合 我们提议的研究将共同​​建立特定的 Par3 条件敲除小鼠。 Par极性蛋白参与AD发病机制的研究结果将揭示AD发病机制。 散发性 AD 的机制，其中衰老是主要危险因素，极性失调可能是 共同特征。