Modulation of A-beta production in Alzheimer's disease

阿尔茨海默病(AD)患者表现出广泛的脑部异常。阿尔茨海默病的特征之一是主要由Abeta组成的老年斑的花样沉积。在一些个体中，家族性早发性AD(FAD)可归因于淀粉样前体蛋白(APP)基因的特定突变。最近，研究表明Abeta水平受早老素1和2基因(PS1和PS2)突变的影响。这有力地证明了AD可能涉及APP新陈代谢的紊乱。相应地，人们对了解调节Abeta产生的基因和制剂的分子作用也有极大的兴趣。为了实现这一目标，已经取得了很大进展。然而，关于调节Abeta产生的亚细胞机制，特别是在神经元(受AD影响最大的细胞)中，仍有许多有待阐明。APP的翻译后处理是非常复杂的，涉及到以细胞类型特定方式发挥作用的途径。这个项目的主要目标之一是解剖和分析在PS1中存在突变的神经元中处理APP和Abeta的亚细胞通路。为了实现这一点，APP处理将在PS1 M146V突变“敲入”内源性小鼠PS1基因的转基因小鼠的原代神经元中进行检测。这些细胞将被载体(塞姆利基森林病毒和单纯疱疹病毒-1/扩增子)感染，这些载体经改造后可表达APP和PS1中的野生型和FAD相关突变，以及APP贩运/分类突变。同样，将对PS1缺陷小鼠的神经元进行检查，以进一步评估PS1在APP处理中的作用。有趣的是，雌激素，一种具有许多神经生物学活性的物质，已经被证明可以减少Abeta的产生。为了深入了解雌激素对抗Abeta产生的机制，本项目的另一个目标是确定受雌激素作用影响的APP/Abeta处理途径。这些研究将在原代培养的大鼠神经元和人神经元NT2N细胞系中进行。这些研究可能会为调节神经元APP和Abeta处理的特定亚细胞器和运输途径提供新的见解。这些信息可能被证明对设计新的策略来预防或控制阿尔茨海默病的病理事件很重要。

Alzheimer's disease (AD) patients display a wide range of brain abnormalities. One of the hallmarks of AD is the florid deposition of senile plaques composed chiefly of Abeta. In some individuals familial early-onset AD (FAD) is attributable to specific mutations in the Amyloid Precursor Protein (APP) gene. Recently, it has been shown that Abeta levels are affected by mutations in the Presenilin 1 and 2 genes (PS1 and PS2). This argues strongly that AD may involve disturbances in APP metabolism. Correspondingly, there is tremendous interest in understanding the molecular actions of genes and agents that regulated Abeta production. Toward this goal much progress has been made. However, much remains to be elucidated regarding the subcellular mechanisms by which Abeta production is modulated, particularly in neurons (the cells most affected by AD). Post-translational processing of APP is highly complex, involving pathways that function in cell-type specific ways. One of the primary goals of this project is to dissection and analyze the subcellular pathways that process APP and Abeta in neurons harboring mutations in PS1. To accomplish this, APP processing will be examining in primary neurons derived from transgenic mice with PS1 M146V mutation "knocked into" the endogenous murine PS1 gene. These cells will be infected with vectors (Semliki Forest virus and Herpes Simplex Virus-1/amplicons) engineered to express wild-type and FAD-related mutations in APP and PS1, as well as APP trafficking/sorting mutations. Similarly, neurons from PS1-deficient mice will be examined to further assess the role of PS1 in APP processing. Interestingly estrogen, a substance with a number of neurobiological activities, has been shown to reduce Abeta production. To gain insight into the mechanisms by which estrogen opposes the generation of Abeta, another goal of this project is to identify the APP/Abeta processing pathways that are affected by the action of estrogen. These studies will be carried out in cultured primary rat neurons and the human neuronal NT2N cell line. These studies will likely provide new insights into the specific subcellular organelles and trafficking pathways that modulate neuronal APP and Abeta processing. This information may prove important in designing new strategies to prevent or control the pathological events underling Alzheimer's disease.