Development of a GBA p.E326K associated Parkinsons disease and Dementia with Lewy body mouse model

戈谢病（GD）是最常见的常染色体隐性遗传性溶酶体贮积病之一， 葡萄糖脑苷脂酶（GBA）基因突变。由GBA编码的酶Gcase 1催化 葡糖神经酰胺（GlcCer）转化为葡萄糖和神经酰胺。GD的主要缺陷是 GlcCer在溶酶体中积累，并且在巨噬细胞中最显著。我们和其他人已经 表明GBA基因中的特定突变，在杂合状态下，是帕金森氏症的危险因素 疾病（PD）和路易体痴呆（DLB）。功能研究表明， α-突触核蛋白与GBA蛋白之间存在着一定的联系，突变的GBA蛋白可以引起α-突触核蛋白（SNCA）的增加， 水平和溶酶体功能障碍。在与PD相关的GBA变体中，p.E326K是最常见的变体之一。 频繁。有趣的是，GBA p.E326K变体仅当在相同等位基因中发现时才参与GD（在GD中）。 顺式）与其他“严重”型突变（例如p.L444P），并通过进一步降低GD的严重程度而促成GD的严重程度。 残余酶活性。尽管生化观察表明p.E326K是一种“轻度”型损失， 对于功能变体，这种活性降低显然不足以严重到导致GD表型。 了解特定GBA突变和PD之间的机制联系对于开发靶向治疗至关重要。 治疗方法。目前，尚不清楚GBA p.E326K突变如何导致神经系统疾病。 大脑中的表型和病理学。最近的研究表明，神经酰胺代谢及其 代谢物在GBA相关的PD和DLB的疾病发病机制中起核心作用。我们假设 GBA p.E326K变异体通过涉及其它蛋白质的不平衡（增加）的机制导致疾病。 神经酰胺代谢途径中的代谢物，即葡萄糖基鞘氨醇（GlcSph）和鞘氨醇 (Sph)导致α-突触核蛋白聚集和ER应激。目前，治疗GBA的治疗方法 相关PD仅限于葡萄糖神经酰胺合酶抑制剂和分子伴侣氨溴索 盐酸盐，两者目前都在临床试验中。小鼠模型的开发， 与PD相关的常见GBA变体，GBA p.E326K变体，并确定疾病机制 可能为神经酰胺途径中靶向ASAH 1或GBA 2的治疗开发开辟新途径 并可能对该领域产生重大影响。本提案的目标是开发和描述Gba p.E326K小鼠模型，可用于未来研究中的治疗开发。我们提出两个具体的 目标。具体目的1是生成和表征PD和DLB的Gba p.E326K小鼠模型，并且具体目的1是生成和表征PD和DLB的Gba p.E326K小鼠模型。 目的2是确定人A30 P α-突触核蛋白（SNCA）转基因的过表达是否改变了人A30 P α-突触核蛋白（A30 P α-synuclein，SNCA）的表达。 在Gba p.E326K小鼠中的抑制率并影响神经症状的发作和进展的年龄。

Gaucher disease (GD), one of the most common autosomal recessive lysosomal storage disorders, is caused by mutations in the Glucocerebrosidase (GBA) gene. The enzyme encoded by GBA, Gcase1, catalyzes the conversion of glucosylceramide (GlcCer) to glucose and ceramide. The primary defect in GD is the accumulation of GlcCer in lysosomes and is seen most prominently in macrophages. We and others have shown that specific mutations in the GBA gene, in the heterozygous state, are a risk factor for Parkinson’s disease (PD) and dementia with Lewy bodies (DLB). Functional studies have demonstrated an interaction between α-synuclein and GBA protein and mutant GBA proteins can cause an increase in α-synuclein (SNCA) levels and lysosomal dysfunction. Among the GBA variants associated with PD, p.E326K is one of the most frequent. Interestingly, the GBA p.E326K variant is only involved in GD when it is found in the same allele (in cis) with other ‘severe’ type mutations (e.g. p.L444P) and contributes to GD severity by further reducing residual enzyme activity. Although biochemical observations have suggested that p.E326K is a ‘mild’ type loss of function variant, this reduction in activity is clearly not severe enough to lead to a GD phenotype. Understanding the mechanistic links between specific GBA mutations and PD is critical for developing targeted therapeutic approaches. Currently, it is unclear how the GBA p.E326K mutation contributes to a neurological phenotype and pathology in the brain. More recent studies suggest that ceramide metabolism and its metabolites play a central role in disease pathogenesis of GBA-associated PD and DLB. We hypothesize that the GBA p.E326K variant, contributes to disease by a mechanism involving an imbalance (increase) of other metabolites in the ceramide metabolism pathway namely Glucosylsphingosine (GlcSph) and Sphingosine (Sph) leading to α-synuclein aggregation and ER stress. Currently, therapeutic approaches to treat GBA associated PD are limited to a glucosylceramide synthase inhibitor and a molecular chaperone, ambroxol hydrochloride, both of which are currently in clinical trials. Development of a mouse model for the most common GBA variant associated with PD, the GBA p.E326K variant, and determining the disease mechanism may open up new avenues for therapeutic development targeting ASAH1 or GBA2 in the ceramide pathway and could have a major impact on the field. The goal of this proposal is to develop and characterize a Gba p.E326K mouse model that can be used for therapeutic development in future studies. we propose two specific aims. Specific Aim 1 is to generate and characterize a Gba p.E326K mouse model of PD and DLB and Specific Aim 2 is to determine whether overexpression of the human A30P α-synuclein (SNCA) transgene modifies penetrance in Gba p.E326K mice and affects age of onset and progression of neurological symptoms.