Understanding Susceptibility to Parkinson's Disease due to GBA1 Mutations

项目总结 帕金森氏病(PD)是第二常见的神经退行性疾病，约有6万退伍军人 目前每年接受退伍军人管理局医疗保健系统的帕金森病治疗。帕金森病的特点是进行性 运动功能减退和认知障碍。尽管医疗负担很大，但我们对 帕金森病的发病机制和治疗方法仍然有限。 葡萄糖苷酶基因突变，即β-酸1(GBA1)是最强的遗传风险因素 特发性帕金森病，与对照组相比，GBA1突变携带者的风险增加了~5倍。然而，大多数 携带GBA1突变的个体不会患上帕金森病，这表明额外的遗传修饰物会影响帕金森病 敏感度。识别这些修饰物将有助于深入了解帕金森病的发病机制，并揭示 疾病修正疗法的新靶点。拟议的工作重点是确定遗传修饰物 使用这些修饰物的果蝇GBA1缺陷模型的GBA1介导的神经变性 了解导致帕金森病的致病机制，并确定在 果蝇可以翻译成临床上相关的人类疾病的修饰物。 候选修饰物将通过使用GBA1缺陷果蝇模型的遗传筛查来确定 这是我开发的(目标1)。两种候选修饰剂，洗脑(BWA)和葡萄糖神经酰胺转移酶 1(GlcT-1)已在初步工作中被鉴定。这些修饰剂在神经酰胺中的作用 新陈代谢提示神经酰胺水平降低可能是GBA1介导的 神经退行性变。我推测神经酰胺水平的降低损害了自噬小体与 溶酶体，导致神经退化。我将通过确定脂质丰度的变化来检验这一假设 在BWA和GlcT-1基因过表达或功能丧失的GBA1突变体和对照果蝇中，检测 结果对自噬通量和自噬小体形态的影响(目标2)。我还将测试是否会增加 直接通过膳食补充神经酰胺水平可以改善GBA1突变表型， 包括受损的自噬。这些研究将阐明脂代谢和脂肪代谢之间的机制联系 GBA1介导的致病机制中的病理性蛋白质聚集，至今仍难以捉摸。在《目标3》中，我会 通过分析Bwa和GlcT-1的人类同源基因，测试它们是否也是人类疾病的修饰物 GBA1携带者和GBA1携带者纵向队列中与症状进展速度相关的修饰物 帕金森病非携带者(目标3)。 拟议的工作使用了几种创新的方法，包括一种新的GBA1无脊椎动物模型 缺乏表现为帕金森病的表型，测试脂代谢在自噬中的作用 基因扰动和饮食补充，并试图将果蝇的研究结果转化为 帕金森病患者的模型。这项工作将大大促进我们对帕金森病发病机制的理解，并可能 揭示新的治疗靶点和新的脂体生物标志物。 我计划使用AIMS 2和AIMS 3中提出的方法来研究其他 通过提议的工作确定的修饰语。这将为新发现提供令人兴奋的途径， 阐明帕金森病的致病机制，并形成优秀奖提案的基础，将 在CDA2期间提交。我对导致神经退行性变的脂代谢改变感兴趣，以及 从一个果蝇模型到一群PD患者的研究结果的翻译已经使我与我的 导师，在这些领域的额外培训将使我成功地过渡到独立的 研究人员将果蝇的机械实验工作与人类的临床相关发现相结合。

PROJECT SUMMARY Parkinson’s disease (PD) is the second most common neurodegenerative disease, and ~60,000 veterans currently receive care for PD from the VA Health Care System annually. PD is characterized by progressive motor decline and cognitive impairment. Despite significant medical burden, our understanding of the pathogenesis of PD and therapies remain limited. Mutations in the gene glucosidase, beta acid 1 (GBA1) are the strongest genetic risk factor for developing idiopathic PD, increasing risk by ~5-fold in GBA1 mutation carriers compared to controls. However, most individuals with GBA1 mutations do not develop PD, suggesting that additional genetic modifiers influence PD susceptibility. Identification of these modifiers would provide insight into the pathogenesis of PD, and reveal novel targets for disease-modifying therapies. The proposed work focuses on identifying genetic modifiers of GBA1-mediated neurodegeneration using a Drosophila GBA1 deficient model, using these modifiers to understand the pathogenic mechanisms causing PD, and determining whether modifiers identified in Drosophila translate to clinically relevant modifiers of human disease. Candidate modifiers will be identified through a genetic screen using a GBA1 deficient Drosophila model that I have developed (Aim 1). Two candidate modifiers, brainwashing (bwa) and glucosylceramide transferase 1 (GlcT-1) have already been identified in preliminary work. The function of these modifiers in ceramide metabolism suggests that decreased levels of ceramide may be responsible for GBA1-mediated neurodegeneration. I hypothesize that decreased ceramide levels impair fusion of autophagosomes to lysosomes, causing neurodegeneration. I will test this hypothesis by identifying alterations of lipid abundances in GBA1 mutant and control flies with overexpression or loss of function of bwa and GlcT-1, and examining resulting effects on autophagy flux and autophagosome morphology (Aim 2). I will also test whether increasing levels of ceramide directly through dietary supplementation can ameliorate GBA1 mutant phenotypes, including impaired autophagy. These studies will elucidate the mechanistic link between lipid metabolism and pathologic protein aggregation in GBA1-mediated pathogenesis, which has remained elusive. In Aim 3, I will test whether bwa and GlcT-1 are also modifiers of human disease, by analyzing human homologs of these modifiers for association with rate of progression of symptoms in a longitudinal cohort of GBA1 carriers and noncarriers with PD (Aim 3). The proposed work uses several innovative approaches, including a novel invertebrate model of GBA1 deficiency manifesting phenotypes suggestive of PD, testing the role of lipid metabolism on autophagy through genetic perturbations and dietary supplementation, and attempting to translate findings from a Drosophila model to PD patients. This work will significantly advance our understanding of PD pathogenesis, and could reveal novel therapeutic targets and new lipidomic biomarkers. I plan to use the proposed methodologies in Aims 2 and 3 to investigate the mechanisms of additional modifiers identified through the proposed work. This will provide exciting avenues for new discoveries, elucidate pathogenic mechanisms responsible for PD, and form the basis for a Merit Award proposal, to be submitted during the CDA2. My interests in lipid metabolism alterations contributing to neurodegeneration, and translation of findings from a Drosophila model to a cohort of PD patients already differentiate me from my mentors, and the additional training in these areas will allow me to successfully transition to an independent researcher combining mechanistic experimental work in Drosophila with clinically relevant findings in humans.