The role of PS1 in regulation of adult neurogenesis in the intact and Alzheimer?s

描述(申请人提供)：阿尔茨海默病患者患有严重的神经元损伤，表现为进行性记忆丧失和认知恶化。阿尔茨海默氏症患者目前无法治疗，如果我们能够理解调节神经发生的机制以及如何操纵它们，他们可能会从内源性神经元的新生中受益。早老素-1(PS1)是一种在天冬氨酸蛋白酶3-分泌酶中起主要作用的多通路蛋白。PS1编码基因的突变会导致家族性阿尔茨海默病(FAD)。最近的证据表明，PS1在成人神经发生中起作用。为了深入了解PS1在神经发生中的作用，这一过程发生在成人大脑的离散区域，我们开发了一种慢病毒载体系统，表达小干扰RNA(SiRNA)用于PS1靶向，以及绿色荧光蛋白用于跟踪转导细胞。我们发现，将这些慢病毒载体立体定向注射到成人大脑的神经源性区域，显著降低了神经干细胞的增殖并诱导了星形胶质细胞的分化。基于我们有趣的初步结果，我们假设PS1在成人大脑的神经干细胞增殖和细胞命运决定中起主要作用。在特定目的1中，我们建议通过检测PS1沉默对成人脑内神经干细胞的影响来确定PS1在调节神经干细胞增殖、迁移和决定细胞命运中的作用。在特定目标2中，我们建议定义PS1在调节神经干细胞的神经源性生态位和内在通路中的作用。这将通过在表达巢蛋白的神经干细胞和表达胶质纤维酸性蛋白的星形胶质细胞中以特定细胞类型的方式表达PS1沉默的siRNA来实现。在具体目标3中，我们建议确定PS1在成人大脑学习和记忆中的作用。通过行为分析，我们将检验神经发生区神经干细胞中PS1沉默对学习和记忆过程的影响。在特定的目标4中，我们建议通过产生转基因小鼠来确定FAD连锁突变体PS1对成人神经发生的影响，转基因小鼠将在成年大脑中唯一地表达FAD连锁PS1变异体。这项研究提出了强有力的方法来确定PS1在神经发生中的作用，以及阿尔茨海默病病理对这一过程的影响。这些研究可能对衰老和阿尔茨海默氏症的大脑具有深远的治疗意义。公共卫生相关性：调节神经发生作为一种治疗策略具有很大的前景。诱导新神经元的形成并支持它们在局部回路中的功能整合的能力可能会补偿退化神经元的丧失和记忆障碍，这是阿尔茨海默病(AD)的特征。这个项目将研究AD中的一个关键角色，即早老素-1(PS1)在调节成人大脑中的神经发生中的作用。这些研究的结果可能为治疗或预防人类疾病的发展提供策略。

DESCRIPTION (provided by applicant): Patients affected with Alzheimer's disease suffer from severe neuronal damage, manifested by progressive memory loss and cognitive deterioration. Alzheimer's patients, who are currently untreatable, may benefit from the endogenous de novo generation of neurons, if we are able to understand the mechanisms that regulate neurogenesis, and how to manipulate them. Presenilin-1 (PS1) is a multi-pass protein that plays a major role in the aspartyl protease 3-secretase. Mutations in the gene encoding PS1 cause Familial Alzheimer's disease (FAD). Recent evidence suggests that PS1 plays a role in adult neurogenesis. To gain an insight into the role of PS1 in neurogenesis, a process that takes place in discrete areas of the adult brain, we developed a lentiviral vector system that expresses small interfering RNAs (siRNA) for PS1 targeting, and green fluorescent protein for the tracking of transduced cells. We show that stereotaxic injection of these lentiviral vectors into neurogenic areas in the adult brain dramatically reduces neural stem cell proliferation and induces astrocyte differentiation. Based on our intriguing preliminary results we hypothesis that PS1 plays a major role in neural stem cell proliferation and cell fate determination in the adult brain. In Specific Aim 1 we propose to determine the role of PS1 in regulation of neural stem cell proliferation, migration and cell fate determination by examining the effect of PS1 silencing on neural stem cells in the adult brain. In Specific Aim 2 we propose to define the role of PS1 in regulation of the neurogenic niche and of intrinsic pathways in neural stem cells. This will be achieved by expression of siRNA for PS1 silencing in a cell type-specific manner, in nestin-expressing neural stem cells and glial fibrillary acidic protein-expressing astrocytes. In Specific Aim 3 we propose to determine the role of PS1 in learning and memory in the adult brain. Using behavioral analysis, the effect of PS1 silencing in neural stem cells in neurogenic areas on learning and memory processes will be examined. In Specific Aim 4 we propose to determine the effect of FAD-linked mutant PS1 on adult neurogenesis by the generation of transgenic mice that will express FAD-linked PS1 variants in neural stem cells exclusively in the adult brain. This study proposes powerful approaches for the determination of the role of PS1 in neurogenesis and of the effect of Alzheimer's pathology on this process. These studies may have far-reaching therapeutic implications in the aging and Alzheimer's brain. PUBLIC HEALTH RELEVANCE: Modulation of neurogenesis holds great promise as a therapeutic strategy. The ability to induce formation of new neurons and support their functional integration in local circuits may compensate for loss of degenerating neurons and memory impairments, characterizing Alzheimer's disease (AD). This project will investigate the role of a critical player in AD, namely, presenilin-1 (PS1) in regulating neurogenesis in the adult brain. The results of these studies may provide strategies to treat or prevent the development of the human illness.