Role of ABeta-Degrading Proteases in Alzheimer's Disease

描述（由申请人提供）：尽管大量研究支持淀粉样蛋白β (a β)在阿尔茨海默病（AD）发病机制中的核心作用，但在绝大多数情况下，肽积累的潜在原因尚不清楚。只有少数病例（<5%）涉及A - β的过量产生，并且新产生的AB迅速从大脑中清除，这表明A - β降解蛋白酶可能在调节大脑中肽水平方面发挥重要作用。尽管很多工作都集中在A β的产生上，但对A β蛋白水解的了解相对较少，而A β蛋白水解在AD的发病机制和/或潜在治疗中可能同样重要甚至更重要。研究得最好的两种A - β降解蛋白酶是NEP和IDE。有人类遗传证据显示，在一些人群中，染色体10q的IDE区域与AD和2型糖尿病（DM2）都有联系，鉴于越来越多的证据表明DM2和高胰岛素血症与AD发病风险增加有关，这一发现令人感兴趣。该建议的中心假设是IDE和NEP是体内A β水平的重要调节因子，这些蛋白酶的缺陷可能是AD病例的基础。我的目标是：1)通过两种动物模型确定IDE功能障碍是否导致体内A β和胰岛素分解代谢下降；2)通过基因缺失小鼠与人APP转基因小鼠的杂交，评估IDE和NEP在体内对人A β亚型代谢的相对作用。3)通过定量转录本和使用报告基因构建确定AD家族中IDE基因5'非翻译区（UTR）已知多态性的生物学意义，该区域与10q染色体等位基因相关。4)检查IDE正常细胞生物学的几个方面，如可能的gpi锚点，CSF和血清中的同种异构体，并寻找天然结合伙伴。该K08提案的目标是获得必要的细胞和分子生物学，动物育种策略和统计分析方面的科学培训，使候选人能够验证上述假设，并在此过程中，使候选人能够发展成为一名成功和独立的医生-科学家，具有帮助神经退行性痴呆患者的技能。候选人的职业发展规划、世界一流的培训环境以及所在部门的承诺将使这一目标得以实现。

DESCRIPTION (provided by applicant): Although an impressive number of studies support a central role for amyloid beta-protein (A beta) in the pathogenesis of Alzheimer's disease (AD), in the vast majority of cases, the underlying causes for the peptide's accumulation are unknown. Overproduction of A beta has been implicated in only a few cases (<5%), and newly generated AB is rapidly cleared from the brain, suggesting that A beta-degrading proteases could play a vital role in regulating cerebral levels of the peptide. Although much work has focused on the generation of A beta, relatively little is known about A beta proteolysis, which could be equally or even more important in the pathogenesis and/or potential treatments of AD. The two best-studied A beta-degrading proteases are neprilysin (NEP) and insulin-degrading enzyme (IDE). There is human genetic evidence showing linkage of the IDE region of chromosome 10q to both AD and type 2 diabetes mellitus (DM2) in some populations, which is intriguing in light of the growing evidence that DM2 and hyperinsulinemia are associated with an increased risk of developing AD. The central hypothesis of this proposal is that IDE and NEP are important regulators of A beta levels in vivo and defects in these proteases may underlie some cases of AD. My Aims are to: 1) Determine whether dysfunction of IDE leads to decreased A beta and insulin catabolism in vivo using two animal models, 2) Assess the relative roles in vivo of IDE and NEP in the metabolism of the human isoform of A beta by breeding gene-deleted mice to human APP transgenic mice, 3) Determine the biological significance of the known polymorphisms in the 5' un-translated region (UTR) of the IDE gene in AD families with allelic association to this region of chromosome 10q by quantifying transcripts and using reporter constructs and 4) Examine several aspects of the normal cell biology of IDE, such as a possible GPI-anchor, isoforms in the CSF and serum, and search for natural binding partners. The goal of this K08 proposal is to obtain the necessary scientific training in cell and molecular biology, animal breeding strategies, and statistical analysis to allow the candidate to test the above hypothesis as outlined, and in doing so, allow the candidate to develop into a successful and independent physician-scientist with the skills to help individuals with neurodegenerative dementias. The candidate's career development plan, world-class training environment, and commitment from his Department will allow the realization of this goal.