Metabolo-Genetic Dissection of GBA and Lysosomal Genes in Parkinson's Disease and Lewy Body Dementia

共核病，包括路易体痴呆(LBD)和帕金森病(PD)，是常见的和 有强有力的遗传证据的不可治愈的神经退行性疾病。中的功能丧失变种 葡萄糖脑苷酶(GBA)导致高谢病，一种隐性溶酶体储存障碍(LSD)。它是 估计需要85%或更多的葡萄糖脑苷酶活性丧失才能触发Gaucher‘s。 然而，矛盾的是，GBA变异体的杂合子携带者-导致总酶适度下降 功能--帕金森病和腰椎病的风险显著增加，GBA等位基因也显著修改了 帕金森病患者中的痴呆症。新的证据表明，GBA功能的丧失可能会增强 帕金森病患者聚集形成脑路易小体的病理蛋白α-突触核蛋白(α-Syn)的神经毒性 和LBD。然而，GBA活性部分降低的机制有助于 并核病仍然难以捉摸。由于大多数GBA变异携带者在他们的一生中不会发展为疾病， 其他因素可能也会导致疾病的外显性。在一项外显子组范围的研究中，我们发现了一个聚集体 54个LSD基因中与帕金森病风险相关的遗传变异负担。事实上，超过一半的受试者在 至少一个变异体，21%携带两个或更多变异体。这些结果表明：(I)其他LSD基因可能 以及(Ii)LSD基因变异可能相互作用，以改变风险和 神经退行性变的进展。在这个提议中，我们检验了部分、单倍性不足的假设 LSD基因功能丧失扰乱鞘磷脂新陈代谢，导致溶酶体应激增强 并且增加了对αSYN诱导的年龄依赖性神经变性的易感性。在令人信服的 初步研究，我们已经对94个保守的同源基因进行了全面的遗传操作 转α基因果蝇神经变性模型中人LsD基因的表达 和其他17个候选增强剂。一种优势修饰物与溶酶体代谢有关 神经酰胺和鞘磷脂。在这里，我们将利用果蝇中强大而快速的遗传学来 系统确认LSD基因与αSYN介导的神经退行性变之间的相互作用 评估对αSyn蛋白质动力学和目标1b；的影响。为了建立临床相关性，LSD基因修饰物 αSYN将在人脑尸检队列中检查与帕金森病/腰椎间盘突出症病理的相关性。在……里面 同时，最有希望的αsyn的lsd基因修饰物将被询问对溶酶体结构的影响 和函数&lt；Aim 2a&gt；，我们将执行质谱学来描述GBA中的鞘脂扰动 葡萄糖脑苷酶活性逐渐降低的等位基因系列&目标2b和gt；总而言之，这种探索性 该项目将在GBA部分功能丧失和其他导致LSD的基因之间建立因果关系链 溶酶体代谢的亚临床紊乱，α系统衰老脑、神经元的神经病理学 功能障碍和死亡，最终是PD/LBD的临床表现。

Synucleinopathies, including Lewy body dementia (LBD) and Parkinson’s disease (PD), are common and incurable neurodegenerative disorders with strong evidence for heritability. Loss-of-function variants in Glucocerebrosidase (GBA) cause Gaucher’s disease, a recessive lysosomal storage disorder (LSD). It is estimated that 85% or greater loss of Glucocerebrosidase activity is required to trigger Gaucher’s. Paradoxically however, heterozygous carriers of GBA variants—causing modest reductions in overall enzyme function—have a significantly increased risk of PD and LBD, and GBA alleles also dominantly modify risk of dementia among subjects with PD. Emerging evidence suggests that GBA loss of function may enhance the neurotoxicity of α-synuclein (αSyn), the pathological protein that aggregates to form brain Lewy bodies in PD and LBD. However, the mechanism by which partial reduction in GBA activity contributes to pathogenesis of synucleinopathy remains elusive. Since most GBA variant carriers do not develop disease in their lifetimes, other factors likely contribute to disease penetrance. In an exome-wide study, we discovered an aggregate genetic variant burden among 54 LSD genes associated with PD risk. In fact, over half of subjects carried at least one variant, and 21% carried 2 or more variants. These results suggest that (i) other LSD genes likely contribute to synucleinopathy, and (ii) LSD gene variants may interact with one another to modify risk and progression of neurodegeneration. In this proposal we test the hypothesis that partial, haploinsufficient loss of function in LSD genes disrupts sphingolipid metabolism, leading to enhanced lysosomal stress and increased vulnerability to αSyn-induced, age-dependent neurodegeneration. In compelling preliminary studies, we have performed comprehensive genetic manipulations of 94 conserved homologs of human LSD genes in a Drosophila transgenic model of αSyn-mediated neurodegeneration, identifying GBA and 17 other candidate enhancers. A preponderance of modifiers are implicated in lysosomal metabolism of ceramide and sphingolipids. Here, we will employ the powerful and rapid genetics available in Drosophila to systematically confirm interactions between LSD genes and αSyn-mediated neurodegeneration <Aim 1a> and assess impact on αSyn protein dynamics <Aim 1b>. To establish clinical relevance, LSD gene modifiers of αSyn will be examined for associations with PD/LBD pathology in human brain autopsy cohorts <Aim 1c>. In parallel, the most promising LSD gene modifiers of αSyn will be interrogated for impact on lysosomal structure and function <Aim 2a>, and we will perform mass-spectrometry to profile sphingolipid perturbations in a GBA allelic series with graduated reduction in Glucocerebrosidase activity <Aim 2b>. In sum, this exploratory project will establish a causal chain between partial loss-of-function in GBA and other LSD genes leading to subclinical derangements in lysosomal metabolism, αSyn neuropathology in the aging brain, neuronal dysfunction and death, and ultimately, the clinical manifestations of PD/LBD.