Investigating the Role of GDE2 in Neuronal Mitotic Inhibition and Nuclear Pore Complex Defects

项目摘要/摘要 阿尔茨海默病(AD)和相关疾病(ADRD)是导致痴呆症的主要原因，影响着数百万人 每年都有人。尽管这是一个如此普遍的公共卫生问题，但对该病病因的了解 这些疾病中的神经变性是有限的，并阻碍了有效治疗方法的发展。 异常神经细胞周期折返与核孔复合体/核质转运 缺陷分别被认为是AD和ADRDS中神经退行性变的原因现象。 然而，导致这些现象的机制以及它们之间的关系尚不清楚。 我们已经确定了一条涉及甘油磷酸二酯磷酸二酯酶2(GDE2或GDPD5)的途径，该途径 在成年哺乳动物脑中防止CCR和NPC/核质运输缺陷，并在 人死后AD和ALS脑组织。GDE2是三种作用于细胞外基质的六种跨膜酶之一 细胞表面切割将一些蛋白质系在膜上的GPI锚。在胚胎发育过程中，GDE2 抑制祖细胞增殖，促进神经元分化。初步研究表明， 成人大脑中的GDE2会导致CCR和NPC的异常，这些异常发生在明显的神经变性之前。因为 在缺乏GDE2的神经元中，NPC缺陷与CCR一致，并且NPC通常在 有丝分裂，我们假设GDE2对维持神经元在一生中处于有丝分裂后状态和 GDE2缺失引起的Ccr异常导致鼻咽癌的崩溃和神经退行性变。重要的是，GDE2 AD和ADRDS的定位和功能被破坏，增加了GDE2功能障碍的可能性 途径可能参与了这些疾病的发病机制。这项提议将检验我们的中心假设 三个目标。目标1将定义GDE2在维持神经元静止和 衰老小鼠鼻咽癌的完整性，而目标2将定义CCR和鼻咽癌破裂的关系和 找出导致CCR和NPC缺陷的机制。稍后的实验将确定这一点的相关性 人类AD和ADRDS中CCR和NPC破坏的途径(目标3)。这项拟议的研究预计将 确定对神经元生存至关重要的新的生理途径，并将提供新的见解 与人类疾病相关的神经退行性变的原因机制。此外，这个项目还有 巨大的训练潜力。我将有机会提高我在神经科学和细胞生物学方面的知识， 并获得原代细胞培养、病毒结构设计和转导、小鼠遗传学、 脑部解剖和组织准备，以及人体组织的免疫组织化学分析。这项研究 将在高度协作的环境中表演，在那里我将有很多机会获得 高质量的指导和培训，发展我的写作和演讲技能，并成长为一名导师和 更多初级科学家的老师。总体而言，Kirschstein-NRSA拨款将支持我的两项研究，旨在 发现神经退行性变的分子基础和我作为一名独立科学家的发展。

Project Summary / Abstract Alzheimer's disease (AD) and related diseases (ADRDs) are the leading cause of dementia, affecting millions of people each year. Despite being such a prevalent public health concern, knowledge of the etiology of neurodegeneration in these diseases is limited and has stymied the development of effective treatments. Aberrant neuronal cell-cycle reentry (CCR) and nuclear pore complex (NPC)/nucleocytoplasmic transport defects have been separately identified as causal phenomena for neurodegeneration in AD and ADRDs. However, the mechanisms leading to these phenomena and the relationship between them remains unknown. We have identified a pathway involving Glycerophosphodiester phosphodiesterase 2 (GDE2 or GDPD5) that prevents CCR and NPC/nucleocytoplasmic transport defects in the adult mammalian brain and is disrupted in human postmortem AD and ALS brain tissue. GDE2 is one of three six-transmembrane enzymes that act at the cell surface to cleave the GPI-anchor that tethers some proteins to the membrane. During embryogenesis, GDE2 inhibits progenitor cell proliferation to promote neuronal differentiation. Preliminary studies show that loss of GDE2 in the adult brain leads to CCR and NPC abnormalities that precede overt neurodegeneration. Because NPC defects are coincident with CCR in neurons lacking GDE2, and the NPC normally breaks down during mitosis, we hypothesize that GDE2 is important for maintaining neurons in a postmitotic state throughout life and that aberrant CCR elicited by GDE2 loss leads to NPC breakdown and neurodegeneration. Importantly, GDE2 localization and function is disrupted in AD and ADRDs, raising the possibility that dysfunction of the GDE2 pathway could contribute to the pathogenesis of these diseases. This proposal will test our central hypothesis in three aims. Aim 1 will define the physiological requirement for GDE2 in maintaining neuronal quiescence and NPC integrity in aging mice while Aim 2 will define the relationship between CCR and NPC breakdown and identify the mechanisms leading to CCR and NPC defects. Later experiments will determine relevance of this pathway to CCR and NPC disruption in human AD and ADRDs (Aim 3). The proposed research is expected to identify a novel physiological pathway that is essential for neuronal survival and will provide new insight into causal mechanisms of neurodegeneration that are relevant to human disease. In addition, this project has immense training potential. I will have the opportunity to improve my knowledge in neuroscience and cell biology, and to acquire technical expertise in primary cell culture, viral construct design and transduction, mouse genetics, brain dissections and tissue preparation, and immunohistochemical analysis of human tissues. This research will be performed in a highly collaborative environment, where I will have numerous opportunities to receive quality mentorship and training, to develop my written and presentation skills, and to grow as a mentor and teacher to more junior scientists. Overall, the Kirschstein-NRSA grant will support both my research aimed at discovering the molecular basis of neurodegeneration and my development as an independent scientist.