Mechanism of innate immune activation in a Drosophila model of Alzheimer's disease related dementia

阿尔茨海默病相关痴呆果蝇模型中先天免疫激活机制

基本信息

批准号：
10339866
负责人：
Leo J Pallanck
金额：
$ 38.88万
依托单位：
UNIVERSITY OF WASHINGTON
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-02-01 至 2027-01-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10339866
关键词：
ATF2 gene Address Affect Age-associated memory impairment Alzheimer&apos s disease model Alzheimer&apos s disease related dementia Alzheimer&apos s disease risk American Biochemical Biogenesis Biological Assay Biology Blood Brain Defect Development Dimerization Disease Drosophila genus Enzymes Genes Genetic Genetic Transcription Glucosylceramides Glycosphingolipids Hemolymph Immune Immune response Immune system Impairment Innate Immune System Insecta Intervention Lead Lewy Body Dementia Ligands Link Mediating Medical Membrane Mitogens Modeling Mutation Nature Nerve Degeneration Neuraxis Neurodegenerative Disorders Neurofibrillary Tangles Neuroglia Neurons Orthologous Gene Pathogenesis Pathway interactions Persons Pharmacology Phenotype Play Process Production Property Protein Kinase Proteins Proteomics RNA interference screen Receptor Activation Receptor Protein-Tyrosine Kinases Regulation Reporting Risk Risk Factors Role Signal Pathway Signal Transduction Source Sphingolipids Testing Transcript Tyrosine Phosphorylation Ubiquitin Work activating transcription factor base brain cell experimental study extracellular vesicles fly follow-up genetic risk factor glucosylceramidase immune activation innate immune mechanisms innate immune pathways knock-down mutant neuroinflammation novel p38 Mitogen Activated Protein Kinase prevent protein aggregation response transcriptome sequencing upstream kinase vesicular release

项目摘要

ABSTRACT: Lewy body dementia is an Alzheimer’s disease–related dementia that affects more than one million Americans. The strongest risk factor for this devastating neurodegenerative disease is mutation of the GBA gene, which encodes the lysosomal enzyme glucocerebrosidase (GCase). GBA mutations can impair the ability of GCase to break down its substrate, the glycosphingolipid glucosylceramide (GlcCer), but it is not clear how defects in GlcCer breakdown increase the risk of Alzheimer’s disease–related dementias. To study this problem, we created a fly lacking the Drosophila ortholog of GBA, Gba1b, as a model of GCase deficiency. Our Gba1b mutant shows accumulation of GlcCer and recapitulates features of Alzheimer’s disease–related dementias including neurodegeneration, brain protein aggregates, and age-related cognitive decline. We now propose to use the Gba1b mutant to test a novel model of neurodegeneration associated with GCase deficiency, in which GlcCer accumulation leads to neuroinflammation via changes in extracellular vesicles (EVs). In earlier work, we found that Gba1b mutants had increased abundance and turnover of EV proteins, and that genetically suppressing neuronal EV production ameliorated mutant phenotypes. More recently, RNA-Seq experiments revealed that Gba1b mutants had marked innate immune activation. A followup RNAi screen of major innate immune pathways found that neuronal knockdown of two p38 MAPK pathway components, the transcription factor Atf-2 and its upstream kinase licorne, also suppressed Gba1b mutant phenotypes. Based on these and other findings, we hypothesize that immune-mediated neurodegeneration in Gba1b mutants is a process driven by excess GlcCer in two separate roles. Specifically, we hypothesize that excess GlcCer in neurons triggers ligand-independent receptor tyrosine kinase activity and p38 MAPK signaling, stimulating EV release; GlcCer in the released EVs then causes glia to secrete immune effector proteins, leading to protein aggregation and neurodegeneration. We propose three aims to address these hypotheses. The first will delineate the intraneuronal signaling pathway that leads to abnormal EV release; the second will investigate the nature of the EV alterations; the third will determine how those EVs trigger immune effector secretion from glia. Given the abundant evidence for neuroinflammation in Alzheimer’s disease and related dementias, we anticipate that our work will have broad medical significance.

抽象的：路易体痴呆症是一种与阿尔茨海默病相关的痴呆症，影响超过一百万美国人。这种破坏性神经退行性疾病的最强危险因素是 GBA 基因突变，该突变编码溶酶体酶葡萄糖脑苷脂酶 (GCase)，GBA 突变会损害 GCase 的能力。分解其底物，糖鞘脂葡萄糖神经酰胺（GlcCer），但尚不清楚如何缺陷 GlcCer 分解会增加患阿尔茨海默病相关痴呆的风险。为了研究这个问题，我们进行了研究。创建了一种缺乏 GBA 果蝇直系同源物 Gba1b 的果蝇，作为我们的 Gba1b 突变体的模型。显示 GlcCer 的积累并概括了阿尔茨海默病相关痴呆的特征，包括我们现在建议使用神经退行性变、大脑蛋白质聚集和与年龄相关的认知能力下降。 Gba1b 突变体用于测试与 GCase 缺乏相关的神经变性新模型，其中 GlcCer 在早期的工作中，我们发现积累会通过细胞外囊泡（EV）的变化导致神经炎症。 Gba1b 突变体增加了 EV 蛋白的丰度和周转率，并且基因抑制最近，RNA-Seq 实验表明，神经元 EV 的产生改善了突变表型。 Gba1b 突变体具有明显的先天免疫激活作用，主要先天免疫途径的后续 RNAi 筛选。发现两个 p38 MAPK 通路成分（转录因子 Atf-2 及其基于这些和其他发现，我们发现上游激酶 licorne 也抑制了 Gba1b 突变表型。研究表明，GBa1b 突变体中免疫介导的神经变性是由过量 GlcCer 驱动的过程具体来说，我们发现神经元中过量的 GlcCer 会触发配体依赖性。受体酪氨酸激酶活性和 p38 MAPK 信号传导，刺激释放的 EV 中的 GlcCer 释放；然后导致神经胶质细胞分泌免疫效应蛋白，导致蛋白质聚集和神经变性。提出三个目标来解决这些假设。第一个目标是描述神经元内信号传导通路。导致 EV 释放异常；第二个将调查 EV 变化的性质；第三个将确定鉴于神经炎症的大量证据，这些 EV 如何触发神经胶质细胞的免疫效应器分泌。在阿尔茨海默病和相关痴呆症方面，我们预计我们的工作将具有广泛的医学意义。