FUNCTION AND REGULATION OF APL-1, THE C. ELEGANS HOMOLOGUE TO HUMAN APP

李，克莉丝汀 项目摘要 致密斑块的沉积和神经纤维缠结的出现是两个死后 阿尔茨海默病的诊断标准。的主要组分 致密斑块是一种40-42个氨基酸的β-淀粉样肽，其来源于较大的 淀粉样前体蛋白（APP），一种单次跨膜结构域蛋白。携带a APP敲除显示出几种行为和认知缺陷，这些缺陷可以通过 敲入全长APP或仅APP的胞外结构域。然而，APP- 相关蛋白质存在于哺乳动物中。敲除小鼠APP家族导致出生后 致死性和II型无脑回畸形，表明APP家族在 发展我们有兴趣研究APP的功能，正在接近这一点 通过在一个简单的模型系统中检测APP相关基因， 秀丽隐杆线虫apl-1基因敲除导致幼虫死亡， APL-1基因组片段或仅编码 APL-1的细胞外结构域。携带apl-1（yn 5）突变的动物是可行的，产生 高水平的只有APL-1胞外结构域，并显示出几种表型，包括一个 发育缓慢寿命缩短我们对sAPL-1的作用特别感兴趣 以及它的分裂是如何被调节的。我们已经开发出了在sAPL-1裂解后对其进行跟踪的工具 这将使我们能够识别sAPL-1结合的细胞， 在这些细胞中启动的信号通路。干扰α-分泌酶活性的总体变化 APL-1及其裂解产物的水平;这些变化的机制将是 考察了解APL-1的功能，特别是sAPL-1的作用， 深入了解APP在高等动物（如人类）中的功能。

Li, Christine Project Summary Deposition of dense plaques and the presence of neurofibrillary tangles are two postmortem criteria used in the definitive diagnosis of Alzheimer's disease. The major component of the dense plaques is a 40-42 amino acid beta-amyloid peptide that is derived from the larger amyloid precursor protein (APP), a single pass transmembrane domain protein. Mice carrying a knockout of APP show several behavioral and cognitive defects, which can be rescued by knockin of full-length APP or only the extracellular domain of APP. However, a family of APP- related proteins is present in mammals. Knockout of the APP family in mice leads to postnatal lethality and type II lissencephaly, indicating that the APP family has essential functions during development. We are interested in studying the function of APP and are approaching this problem by examining an APP-related gene in a simple model system, the nematode Caenorhabditis elegans. Knockout of apl-1 leads to larval lethality, which can be rescued by germline transformation of an apl-1 genomic fragment or a fragment encoding only the extracellular domain of APL-1. Animals carrying the apl-1(yn5) mutation are viable, produce high levels of only the APL-1 extracellular domain, and show several phenotypes, including a slowed development and shortened lifespan. We are specifically interested in the role of sAPL-1 and how its cleavage is regulated. We have developed tools to follow sAPL-1 after its cleavage at the cell surface, which will allow us to identify the cells to which sAPL-1 binds and the signaling pathway initiated in these cells. Interfering with α-secretase activity changes overall levels of APL-1 and its cleavage products; the mechanism underlying these changes will be examined. Understanding APL-1 function, and particularly the role of sAPL-1, may provide insights into the function of APP in higher animals, such as man.