The effect of GBA1 L444P heterozygous mutation on synaptic morphology in the hippocampus and cognition related to Lewy body dementias

GBA1 L444P杂合突变对路易体痴呆相关海马突触形态及认知的影响

• 批准号: 10660967
• 负责人: Casey Mahoney-Crane
• 金额: $ 3.89万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10660967
• 关键词: Appearance; Area; Behavioral; Biological Models; Brain; Brain region; C-terminal; Cathepsins B; Cognition; Cognitive deficits; Collaborations; Corpus striatum structure; Data; Defect; Dementia; Disease Progression; Endoplasmic Reticulum; Enzymes; Excitatory Synapse; Functional disorder; Genes; Glutamates; Goals; Heterozygote; Hippocampus; Impaired cognition; Impairment; Injections; Laboratory Finding; Learning; Lewy Bodies; Lewy Body Dementia; Lewy body pathology; Lewy neurites; Link; Lysosomes; Measures; Memory; Microscopy; Molecular; Morphology; Mus; Mutation; Nerve Degeneration; Neurobehavioral Manifestations; Neurons; Parkinson Disease; Pathologic; Pathology; Patients; Perfusion; Phenotype; Presynaptic Terminals; Resources; Risk; Role; Saline; Structure; Synapses; Synapsins; Synaptic Cleft; Synaptic Vesicles; Techniques; Testing; Therapeutic; Time; Vertebral column; Virus; Wild Type Mouse; Work; alpha synuclein; behavior test; cohort; dementia risk; genetic risk factor; glucosylceramidase; high risk; improved; monomer; mutant; nanoscale; non-motor symptom; paraform; postsynaptic; pre-formed fibril; presynaptic; prevent; protein aggregation; synaptic function; synucleinopathy; therapy design; trafficking

Project Summary/Abstract: Nearly 80% of Parkinson’s disease (PD) patients develop dementia. PD is pathologically characterized by the accumulation of insoluble aggregates of misfolded α-syn called Lewy bodies and Lewy neurites. The most common genetic risk factor of PD is mutations in the GBA1 gene, which encodes for the lysosomal enzyme glucocerebrosidase (GCase). PD patients with GBA1 mutations (GBA1-PD) show increased risk of dementia and abundant Lewy pathology. Model systems show that expression of mutant GCase increases formation of pathologic α-syn. These data suggest an interaction among mutant GCase, α-syn inclusion formation, and cognitive deficits. PD patients heterozygous for the severe GBA1 L444P mutation (GBA+/L444P) have one of the highest risks of developing dementia (5.6-fold compared to noncarrier of the GBA mutation). GCase produced from GBA1 L444P is not properly folded or trafficked from the endoplasmic reticulum to lysosomes, and data suggest that impaired lysosome function leads to an accumulation of α-syn, which forms pathologic inclusions. Abnormal lysosome activity caused by mutant GBA1 may also impact synaptic structure. The lysosomal enzyme, Cathepsin B (CatB) has been genetically linked to GBA1-PD. Levels of CatB are reduced in the brains of GBA+/L444P mice. Impaired cleavage of α-syn by CatB may lead to an accumulation of α-syn. Thus, the overall goal of this project is to evaluate synaptic degeneration and identify the mechanistic role of CatB activity behind enhanced α-syn aggregation and synaptic changes in the hippocampus of GBA1+/L444P mice. We have found that GBA1+/L444P mice show significantly increased formation of α-syn inclusions, only in the hippocampus. My lab found that early formation of α-syn inclusions in primary hippocampal neurons and in wildtype mice leads to a major loss of excitatory synapses. I propose that α-syn inclusions formation in the hippocampus causes major changes in synaptic structure, enhanced by expression of GBA1+/L444P. My central hypothesis is that decreased CatB expression and activity caused by GBA1+/L444P expression increases the formation of α-syn inclusions, which leads to synaptic degeneration and cognitive impairments. I will test this hypothesis by determining if the GBA1+/L444P mutation enhances synaptic degeneration and leads to cognitive deficits caused by α-synuclein inclusions in the hippocampus. I will also determine if reduced activity of CatB in the hippocampus of GBA+/L444P mice enhances α-syn aggregation. Understanding these mechanisms will lead to therapies designed to modulate enzymatic activity in PD and other synucleinopathies. Through this proposed work, I will continue to learn valuable techniques, such as expansion microscopy to analyze details of synaptic structure, and the use of AAV viruses to increase levels of GCase and CatB, which will allow us to better understand molecular mechanisms that lead to PD. I will also collaborate with experts in GBA1 mutations and neurodegeneration.

项目概要/摘要： 近80%的帕金森病（PD）患者发展为痴呆症。PD的病理特征是 错误折叠的α-syn的不溶性聚集体（称为路易体和路易神经突）的积累。最常见的 PD的遗传风险因素是编码溶酶体酶的GBA 1基因突变 葡糖脑苷脂酶（GCase）。具有GBA 1突变的PD患者（GBA 1-PD）显示痴呆风险增加 和丰富的路易病理学。模型系统显示，突变体GCase的表达增加了 病理性α-syn这些数据表明，突变体GCase，α-syn包涵体的形成， 认知缺陷重度GBA 1 L444 P突变杂合子（GBA+/L444 P）的PD患者具有以下特征之一： 患痴呆症的风险最高（与非GBA突变携带者相比，为5.6倍）。GCase生产 来自GBA 1的L444 P没有正确折叠或从内质网运输到溶酶体，并且数据 提示溶酶体功能受损导致α-syn积聚，形成病理性包涵体。 由突变体GBA 1引起的异常溶酶体活性也可能影响突触结构。溶酶体酶， 组织蛋白酶B（CatB）与GBA 1-PD存在遗传关联。GBA+/L444 P小鼠脑内CatB水平降低 小鼠CatB对α-syn的裂解受损可能导致α-syn蓄积。因此，这一总体目标 项目是评估突触变性，并确定CatB活动背后的机制作用。 增强GBA 1 +/L444 P小鼠海马中α-syn聚集和突触改变。我们有 发现GBA 1 +/L444 P小鼠仅在海马中显示出显著增加的α-syn包涵体形成。 我的实验室发现，在原代海马神经元和野生型小鼠中， 兴奋性突触的严重缺失我认为海马体中α-syn包涵体的形成导致了 突触结构的主要变化，通过GBA 1 +/L444 P的表达增强。我的核心假设是 GBA 1 +/L444 P表达引起的CatB表达和活性降低增加了α-syn的形成， 内含物，导致突触变性和认知障碍。我将通过确定 如果GBA 1 +/L444 P突变增强突触变性并导致α-突触核蛋白引起的认知缺陷， 海马体中的内含物我还将确定GBA+/L444 P海马中CatB活性的降低是否与GBA+/L444 P海马中CatB活性的降低有关。 小鼠增强α-syn聚集。了解这些机制将导致旨在调节 PD和其他突触核蛋白病中的酶活性。通过这份建议的工作，我将继续学习 有价值的技术，如扩展显微镜分析突触结构的细节，以及使用AAV 增加GCase和CatB的水平，这将使我们能够更好地了解分子机制 导致了PD我还将与GBA 1突变和神经变性方面的专家合作。