Neprilysin and Abeta-degradation in Alzheimer's disease

本申请的中心假设是阿尔茨海默病（AD）是一种多因素疾病，其中包括环境决定因素在内的许多因素导致淀粉样蛋白β（Abeta）产生和Abeta清除之间的差异。 这种差异导致A β肽的积累和随后的沉积，这最终导致AD的神经病理学表现。 基于这一假设，许多实验室强调淀粉样前体蛋白（APP）合成和代谢的生物学方面以及AD中Abeta产生的机制。然而，Abeta过度产生的分子机制似乎只占AD总病例的一部分。 Abeta降解和清除的性质是AD进展过程中研究最少的机制，它可能是治疗干预的靶点。 最近的研究表明，中性内肽酶脑啡肽酶在脑内A β（1-42）的降解中起重要作用。 本研究的具体目的是：1）通过将过表达NEP的转基因小鼠或NEP缺陷小鼠与APP转基因小鼠杂交，并对后代进行生化和病理学评估，提供NEP可以调节体内Abeta水平和沉积的证据; 2）使用基于细胞的系统研究NEP对氧化损伤的敏感性;和3）比较人AD脑和年龄匹配对照中的NEP水平/活性，并确定氧化损伤是否有助于改变的NEP活性。 这些研究将有助于确定Abeta如何在细胞外降解，NEP是否在此过程中起关键作用，以及Abeta水平如何受NEP活性的调节。 这项研究产生的结果将有助于我们了解Abeta肽是如何降解的，并可能为治疗AD提供独特的治疗窗口。

The central hypothesis for this application is that Alzheimer's disease (AD) is a multi-factorial disorder in which a number of agents, including environmental determinants, contribute to a disparity between amyloid beta (Abeta) - production and Abeta clearance. This disparity leads to the accumulation and subsequent deposition of Abeta peptides that eventuates in the neuropathological presentation of AD. Based on this hypothesis, numerous laboratories have emphasized the biological aspects of amyloid precursor protein (APP) synthesis and metabolism and the mechanisms of Abeta production in AD. However, the molecular mechanisms of Abeta overproduction appear to contribute to only a portion of the total AD cases. The nature of Abeta degradation and clearance is the least studied mechanism in the process of AD progression and it is a likely target for therapeutic intervention. Recent studies indicate that the neutral endopeptidase neprilysin plays an important role in the degradation of Abeta(1-42) in the brain. The Specific Aims of this proposal are: 1) to provide evidence that NEP can regulate Abeta levels and deposition in vivo, which will be done by crossing transgenic mice overexpressing NEP or NEP-deficient mice with APP transgenic mice and assessing progeny biochemically and pathologically; 2) to use a cell-based system to study the susceptibility of NEP to oxidative damage; and 3) to compare NEP levels/activity in human AD brain and age-matched controls and to determine whether oxidative damage contributes to altered NEP activities. These studies will help determine how Abeta is degraded extracellularly, whether NEP plays a key role in this process, and how Abeta levels are regulated by the activity of NEP. The results generated from this study will help us to understand how Abeta peptides are degraded and may provide a unique therapeutic window for the treatment of AD.