ALZHEIMER'S DISEASE RELATED PRESENILINS

突变的人早老素影响淀粉样前体蛋白(APP)的蛋白分解，导致阿尔茨海默病中神经毒性淀粉样多肽的加速积累。在模式生物线虫、果蝇和小鼠中，早老素是Notch/LIN-12发育信号所必需的。早老素在Notch受体成熟和信号传递过程中调节关键的蛋白降解处理事件，这可能类似于阿尔茨海默病中依赖于早老素的APP的切割。在哺乳动物细胞和果蝇中，早老素也与神经退行性凋亡刺激的细胞反应有关。在FIRCA的应用中，将产生过表达野生型和阿尔茨海默病相关早老素的转基因果蝇。转基因早老素的功能特性将通过几个标准进行评估，包括发育和成体表型的分析，与Notch途径基因的相互作用，对Notch受体加工的影响，以及对细胞凋亡的诱导。人类早老素(PS1和PS2)以及人类APP也将在这个转基因模型中进行功能表征。这些研究将与哺乳动物神经细胞培养中野生型和突变蛋白的平行测试相结合，以评估果蝇和人类早老素在功能上的相似程度。早老素基因受Notch信号输出的转录调控的可能性也将使用这些模型进行测试。这些研究将确定早老素是否是Notch通路上已知的反馈机制的一个组成部分。最后，将对果蝇早老素突变体和其他与早老素相互作用的新突变体进行系统的成年学习和记忆缺陷检查，扩大对这些突变体的发育分析。这一系列明确的研究试图评估果蝇作为人类早老素功能分析的转基因模型的实用性，并揭示苍蝇和人早老素在早期发育以及后期学习和记忆巩固过程中发生的细胞凋亡、神经发生和神经退化中的保守活动。本文提出的研究将阐明早老素在体内处理Notch、APP和其他蛋白质的活性，并最终可能增加我们对人类阿尔茨海默病及其伴随的记忆衰退的分子原因的理解。

Mutant human Presenilins influence the proteolysis of amyloid precursor protein (APP), causing an accelerated accumulation of neurotoxic amyloid peptides in Alzheimer's disease. In the model organisms Caenorhabditis, Drosophila, and the mouse, Presenilins are required for Notch/Lin-12 developmental signaling. Presenilins regulate key proteolytic processing events during Notch receptor maturation and signaling that may be analogous to the Presenilin-dependent cleavages of APP in Alzheimer's disease. Presenilins have also been implicated in the cellular response to neurodegenerative apoptotic stimuli in both mammalian cells and Drosophila. In this FIRCA application, transgenic Drosophila will be generated that overexpress both wild-type and Alzheimer's disease-associated Presenilins. The functional properties of transgenic Presenilins will be assessed by several criteria, including analysis of developmental and adult phenotypes, interactions with Notch pathway genes, effects on Notch receptor processing, and induction of apoptosis. Human Presenilins (PS1 and 2) as well as human APP will also be functionally characterized in this transgenic model. These studies will be coupled with parallel tests of the wild-type and mutant proteins in mammalian neuronal cell culture to assess the degree of functional similarity between Drosophila and human Presenilins. The possibility that Presenilin genes are transcriptionally regulated by Notch signaling output will also be tested using these models. These studies will determine if Presenilin is a component of the feedback mechanism known to operate on the Notch pathway. Finally, Drosophila Presenilin mutants and other new mutants that interact with Presenilin will be systematically examined for adult learning and memory deficits, extending the developmental analysis of these mutants that is already underway. This well-defined set of proposed studies seeks to evaluate the utility of Drosophila as a transgenic model for functional analysis of human Presenilins, and to uncover conserved activities of fly and human Presenilins in apoptosis, neurogenesis, and neurodegeneration that occur during early development as well as during later learning and memory consolidation. The studies proposed here will clarify the in vivo activity of Presenilin in the processing of Notch, APP, and other proteins, and may ultimately increase our understanding of the molecular causes of Alzheimer's disease and its accompanying memory decline in humans.