BACE1 trafficking and degradation in Alzheimer’s disease

阿尔茨海默病中的 BACE1 转运和降解

基本信息

批准号：
9401504
负责人：
GIUSEPPINA TESCO
金额：
$ 310.67万
依托单位：
TUFTS UNIVERSITY BOSTON
依托单位国家：
美国
项目类别：
财政年份：
2017
资助国家：
美国
起止时间：
2017-09-01 至 2022-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9401504
关键词：
Abeta synthesis Adult Affect Age Alzheimer&apos s Disease Alzheimer&apos s disease model Amyloid beta-Protein Amyloid beta-Protein Precursor Apoptosis Astrocytes Autopsy Axon Binding Proteins Brain Brain Diseases CASP3 gene Caspase Cell model Clathrin Adaptors Cleaved cell Cognitive Cognitive deficits Data Deterioration Deubiquitinating Enzyme Ear Early Endosome Enzymes Functional disorder Genetic Goals Golgi Apparatus Hippocampus (Brain)Human Image Impairment In Vitro Induced Mutation Lead Lysosomes Mediating Memory impairment Messenger RNA Microglia Molecular Mus Mutation Neurites Neuritis Neurodegenerative Disorders Neurons Pathologic Pathology Pathway interactions Patients Peptide Hydrolases Presynaptic Terminals Prevention Proteins Rodent Model Role Senile Plaques Site Stress Stroke Synapses Translations Traumatic Brain Injury USP8 gene Ubiquitination abeta toxicity beta-site APP cleaving enzyme 1 experimental study familial Alzheimer disease in vivo induced pluripotent stem cell late endosome mouse model neuronal cell body presynaptic prevent trafficking

项目摘要

ABSTRACT Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by memory impairments and cognitive deterioration. One of the pathological hallmarks of AD is the presence of neuritic plaques, which consist of a core of aggregate amyloid beta (Aβ) closely associated with dystrophic neurites, activated microglia and reactive astrocytes. β-site amyloid precursor protein cleaving enzyme (BACE1) is the rate- limiting enzyme in the production of Aβ. BACE1 is expressed at high levels in neurons and localizes at the presynaptic terminals. Moreover, BACE1 accumulates in dystrophic presynaptic terminals surrounding Aβ plaques in brains of AD patients and mouse models of AD. However, the specific mechanism(s) of BACE1 accumulation in peri-plaque dystrophic axons remains to be clarified. As changes in BACE1 mRNA levels did not accompany BACE1 protein increases in AD brains in the majority of the studies, post-translation mechanisms are most likely responsible for BACE1 elevation in AD. Our previous studies have shown that BACE1 is degraded via the lysosomal pathway. Furthermore, we found that the clathrin adaptor Golgi-localized γ-ear-containing ARF binding protein 3 (GGA3) regulates BACE1 lysosomal trafficking and degradation. More recently, we have discovered that BACE1 degradation and trafficking is regulated by its ubiquitination. Accordingly, we have identified the endosomal-associated deubiquitinating enzyme USP8 as a negative regulator of BACE1 ubiquitination and degradation. The central hypothesis of this proposal is that GGA3 and USP8 regulate BACE1 axonal trafficking and lysosomal degradation in neurons and their dysfunction results in BACE1 accumulation in pre-synaptic dystrophic neurites observed in AD. In support of this hypothesis, we discovered that levels of GGA3 were decreased and inversely correlated with BACE1 levels in post-mortem AD brains concurrently with caspase-3 activation. We also determined that GGA3 is a caspase 3 substrates and is depleted both in cellular models of apoptosis and in rodent models of stroke and traumatic brain injury. Our new preliminary data demonstrated that GGA3 decreases while BACE1 levels increases with age in a mouse model of AD (5XFAD mice). Furthermore, our recent live-imaging experiments revealed that GGA3 genetic deletion results in the disruption of BACE1 axonal trafficking and its accumulation in swollen axons in cultured hippocampal neurons. Altogether our data indicate that GGA3 depletion is a leading candidate mechanism underlying BACE1 accumulation in pre-synaptic dystrophic neurites in AD. Thus we propose 1) to determine the extent to which AD brain-derived Aβ species and Familial Alzheimer's Disease (FAD-linked) mutations impair axonal trafficking and lysosomal degradation of BACE1 in murine and human iPSC-derived neurons; 2) to determine the extent to which preventing caspase-mediated depletion of GGA3 reduces BACE1 accumulation in peri-plaques dystrophic neurites in vivo; 3) to determine the extent to which depletion of USP8 reduces BACE1 accumulation in dystrophic neuritis and ameliorates Aβ pathology and cognitive deficits in vivo.

抽象的阿尔茨海默氏病（AD）是一种以记忆障碍为特征的进行性神经退行性疾病和认知决心。 AD的病理标志之一是神经斑的存在，该斑块的存在由与营养不良的神经运动密切相关的聚集淀粉样蛋白β（Aβ）的核心组成，已激活小胶质细胞和反应性星形胶质细胞。 β地点淀粉样蛋白前体蛋白裂解酶（BACE1）是速率 - 限制Aβ生产中的酶。 Bace1在神经元中以高水平表示，并定位在突触前末端。此外，BACE1在围绕Aβ的营养不良前末端积聚 AD患者的大脑中的斑块和AD的小鼠模型。但是，BACE1的具体机制在斑块周围营养不良轴突中的积累仍有待澄清。随着BACE1 mRNA水平的变化在大多数研究中，不涉及AD大脑的BACE1蛋白增加，译本后机制最有可能导致AD中的BACE1高程。我们以前的研究表明 BACE1通过溶酶体途径降解。此外，我们发现网格蛋白适配器高尔基体定位含γ的ARF结合蛋白3（GGA3）调节BACE1溶酶体运输和降解。更多的最近，我们发现BACE1退化和贩运受到其泛素化的调节。彼此之间，我们已经确定与内体相关的去泛素化酶USP8为负 BACE1泛素化和降解的调节剂。该提议的中心假设是GGA3和 USP8调节神经元中的BACE1轴突运输和溶酶体降解及其功能障碍会导致 BACE1在AD中观察到的突触前营养不良神经运动中的积累。为了支持这一假设，我们发现GGA3的水平得到了改善，并与验尸中的BACE1水平成反比 AD大脑同时与Caspase-3激活。我们还确定GGA3是caspase 3底物并在凋亡的细胞模型和脑损伤和创伤性脑损伤的模型中都耗尽。我们的新初步数据表明，GGA3下降，而BACE1水平随着年龄的增长而增加 AD的小鼠模型（5XFAD小鼠）。此外，我们最近的现场模仿实验表明GGA3 遗传缺失导致Bace1轴突运输的破坏及其在肿胀轴突中的积累培养的海马神经元。我们的数据完全表明GGA3部署是领先的候选人 AD中突触前营养不良神经运动中BACE1积累的基础机制。我们建议1）确定广告脑衍生的Aβ物种和家族性阿尔茨海默氏病的程度（FAD连接）突变会损害鼠类和人IPSC衍生的BACE1的轴突贩运和溶酶体降解神经元； 2）确定防止caspase介导的GGA3部署的程度减少了BACE1 体内斑纹性营养不良神经运动的积累； 3）确定USP8耗尽的程度减少了营养不良神经症中的BACE1积累，并改善了体内Aβ病理学和认知缺陷。