BIOSYNTHESIS AND PROCESSING OF AB IN NT2N CELLS

老年斑是阿尔茨海默病的主要神经病理特征 (AD)主要由淀粉样肽（Abeta）组成， 淀粉样前体蛋白（APP）的作用。两种主要形式 淀粉样蛋白的长度分别为40和42个氨基酸。Abeta（1-40） Abeta（1-40）更容易聚集，占大多数 淀粉样蛋白的表达与家族性疾病相关的APP突变 AD（FAD）通过增加Abeta的总量来改变Abeta的产生。 产生的Abeta，或通过引起相对增加的数量， Abeta（1-40）产生。因此，APP加工和Abeta的扰动 生产可能在AD的发展中起重要作用。因此，我们认为， 项目1的目标是继续描述APP处理 在人神经元模型系统（NT 2N细胞）中的信号通路。我们最近发现 APP在内质网/中间体中的滞留 隔室（ER/IC）阻断Abeta分泌，但细胞内Abeta被阻断。 仍然生产。定量ELISA显示ER/IC相关的Abeta是 仅由Abeta（1-42）组成。这种神经元内的Abeta（1-42） 在NT 2N中积累数周，同时变得不太可溶。 这些观察结果对于理解AD发病机制具有意义， 包括与早老素的可能连接（即，PS1和PS2）， 膜蛋白主要定位于ER/IC，当它们 在FAD谱系中发生突变。有趣的是，FAD相关的形式 早老素突变体增加了Abeta（1-42）的水平。长期 聚集的神经元内Abeta（1-42）的蓄积可能具有神经毒性 并最终导致神经元死亡后SP的形成。我们 我建议扩展我们对这一新途径的研究，以研究其他 产生Abeta的亚细胞区室，并研究其影响 早老素对Abeta产生的影响通过以下具体途径 目的：1）继续我们对ER/IC通路的研究， 产生细胞内Abeta（1-42）; 2）研究潜在的相互作用 早老素和APP之间的关系，并检查野生型 或突变的PS1和PS影响细胞内Abeta的产生; 3）检查 内吞途径在细胞内和细胞外的 分泌的Abeta（1-40）和Abeta（1-42）;和4）研究野生型和 突变形式的APP 751和770由NT 2N神经元加工。

Senile plaques, a major neuropathologic feature of Alzheimer's disease (AD), are composed largely of the amyloid peptide (Abeta) that is derived by processing of the amyloid precursor protein (APP). The two major forms of amyloid are 40 and 42 amino acid long. While Abeta(1-40) is more abundant, Abeta(1-40) aggregates more readily and comprises the majority of the amyloid in SPs. Mutations in APP that are associated with familial AD (FAD) alter the Abeta production by increasing the total amount of Abeta generated, or by causing a relative increase in the amount of Abeta(1-40) produced. Thus, perturbations in APP processing and Abeta production may play an important role in the development of AD. Therefore, the goals of Project 1 are to continue delineation of APP processing pathways in human neuronal model system (NT2N cells). We recently found that retention of APP in the endoplasmic reticulum/intermediate compartment (ER/IC) blocked Abeta secretion, but intracellular Abeta was still produced. Quantitative ELISA showed that ER/IC-associated Abeta is composed exclusively of Abeta(1-42). This intra-neuronal Abeta(1-42) accumulates over a period of weeks in NT2N while becoming less soluble. These observations have implications for understanding AD pathogenesis, including possible links to the presenilins (i.e., PS1 and PS2) which are membrane proteins largely localized to the ER/IC that cause AD when they are mutated in FAD pedigrees. Interestingly, FAD-associated forms of mutant the presenilins increased the levels of Abeta(1-42). Long-term accumulation of aggregated intra-neuronal Abeta(1-42) might be neurotoxic and ultimately lead to the formation of SPs following neuronal death. We propose to extend our studies on this novel pathway, to examine other subcellular compartments where Abeta is produced, and to study the effects of the presenilins on Abeta production through the following Specific Aims: 1) to continue our recent studies on the ER/IC pathway by which intracellular Abeta(1-42) is produced; 2) to study potential interactions between the presenilins and APP, and examine how expression of wild type or mutant PS1 and PS affects intracellular Abeta production; 3) to examine the role of the endocytic pathway in the production of intracellular and secreted Abeta(1-40) and Abeta(1-42); and 4) to study how wild-type and mutant forms of APP751 AND 770 are processed by NT2N neurons.