ALZHEIMER'S DISEASE RELATED PRESENILINS

突变的人早老素影响淀粉样前体蛋白（APP）的蛋白水解，导致阿尔茨海默病中神经毒性淀粉样肽的加速积累。在模式生物隐杆线虫、果蝇和小鼠中，早老素是Notch/Lin-12发育信号通路所必需的。早老素调节Notch受体成熟和信号传导过程中的关键蛋白水解加工事件，这可能类似于早老素依赖的阿尔茨海默病APP裂解。早老素也参与了哺乳动物细胞和果蝇对神经退行性凋亡刺激的细胞反应。在这项FIRCA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，包括发育和成年表型分析、与Notch通路基因的相互作用、对Notch受体加工的影响以及诱导凋亡。人类早老素（PS1和2）以及人类APP也将在该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之间功能相似性的程度。早老素基因受Notch信号输出的转录调节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，果蝇早老素突变体和其他与早老素相互作用的新突变体将被系统地检查成人学习和记忆缺陷，扩展这些突变体的发育分析。这一系列明确的研究旨在评估果蝇作为人类早老素功能分析的转基因模型的效用，并揭示果蝇和人类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、神经发生和神经退行性变中的保守活性。本文提出的研究将阐明早老素在Notch、APP等蛋白加工过程中的体内活性，并可能最终增加我们对阿尔茨海默病及其伴随的人类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.