ZINC AND ALZHEIMERS DISEASE PATHOPHYSIOLOGY

阿尔茨海默病的特征是39-43岁的淀粉样变性沉积 残留的AB肽，以及多项生化异常 大脑。合成的A-β-1-40在高浓度下可溶，其 本地物种最近被描述为脑脊液的成分，但有 没有证据表明它的水平在AD时升高。自表格以来 有特征性淀粉样变性的家族性阿尔茨海默病 由靠近和位于A-β结构域内的致病突变引起的 其母分子(β-淀粉样蛋白前体，APP)， 致病生理因素的鉴定与表征 积聚成淀粉样蛋白的A-β似乎提供了重要线索 与疾病的发病机制有关。在生化异常中 阿尔茨海默病是一种弥漫性的脑锌代谢异常，导致 神经细胞内锌缺乏和间质液体中的锌蓄积。 我们最近发现A-β能与锌特异地、饱和地结合， 对铜也有类似的高度友好。我们发现，空气中 高于300nM的锌迅速使合成的A-β-L-40不稳定为溶液， 并诱导色素淀粉样蛋白的形成。A-β的鼠类， 然而，它对这些影响免疫，与锌的结合不那么强烈， 与这些动物形成大脑A的稀缺性相一致- β淀粉样蛋白。在这个提案中，我们建议描述相互作用的特征 锌与A-β在超微结构和构象水平上的结合 确定低亲和力和高亲和力的后果的程度 锌的相互作用与淀粉样蛋白或前淀粉样蛋白的形成有关。 因此，我们将继续测试A-β的变异形式(例如， A-β1-42和具有天冬氨酸立体异构体取代的A-β)可以 不成比例地富含淀粉样蛋白沉积，因为它们比 比主要的可溶性形式A-更容易引起锌诱导的聚集 贝塔1-40。如果这被证明是真的，那么我们将分析比率A- AD患者脑脊液和脑区的β1-42~A-β1-40。The Rapid 在这些研究中采用的聚合过滤分析将用于 筛选神经化学制剂(如载脂蛋白E和抗氧化剂) 具有抗淀粉样变性的特性。以补充体外培养 将从拟议的研究中收集的结果，我们打算 招募必要的动物和化学数据来开发一种 可能适用于正电子发射断层扫描的同位素标志物 人脑锌代谢的研究。这项提议的目标是 要透彻地理解 AB及其变异体与锌的相互作用及其调节因素 它为进行人体活体研究提供了技术基础 脑锌代谢。总的来说，这些数据将提供一个声音 探索锌在环境中的潜在关键作用的平台 阿尔茨海默病的神经发病机制。

Alzheimer's disease is characterized by amyloidotic deposits of 39-43 residue AB peptides, as well as multiple biochemical abnormalities in the brain. Synthetic A-beta-1-40 is soluble at high concentrations, and its native species has recently been described as a CSF component, but there is no evidence to indicate that its level is increased in AD. Since forms of familial Alzheimer's disease with characteristic amyloid pathology are caused by pathogenic mutations close to and within the A-beta domain of its parent molecule (the beta-amyloid protein precursor, APP), identification and characterization of physiological factors which cause A-beta to accumulate into amyloid would appear to provide important clues to the pathogenesis of the disease. Among the biochemical abnormalities of AD is a pervasive abnormality of cerebral zinc metabolism causing intraneuronal zinc deficiency and accumulation in the interstitial fluid. We have recently shown that A-beta specifically and saturably binds zinc, and has a similar high amity for copper. We found that concentrations of zinc above 300 nM rapidly destabilize synthetic A-beta-l-40 to solutions, and induce tinctorial amyloid formation. The rat species of A-beta, however, is immune from these effects, and binds zinc less avidly, consistent with the scarcity with which these animals form cerebral A- beta amyloid. In this proposal we propose to characterize the interaction of zinc with A-beta at the ultrastructural and conformational levels to determine the extent to which the consequences of low and high affinity zinc interaction are of relevance to amyloid or preamyloid formation. Hence, we will proceed to test whether the variant forms of A-beta (eg, A-beta 1-42 and A-beta with aspartate stereoisomer substitutions) could be disproportionately enriched in amyloid deposits because they are more vulnerable to zinc-induced aggregation than the major soluble form, A- beta 1-40. If this is shown to be true, then we will assay the ratios A- beta 1-42 to A-beta 1-40 in the CSF and brain regions in AD. The rapid aggregate filtration assay employed in these studies will be used to screen neurochemical agents (such as apolipoprotein E and antioxidants) for their anti-amyloidotic properties. To complement the in vitro findings that will be assembled from the proposed studies, we intend to recruit the necessary animal and chemical data required to develop an isotopic marker that may be suitable for positron emission tomography studies of human cerebral zinc metabolism. The goal of this proposal is to develop a thorough understanding of the structural consequences of the interaction of AB and its variants with zinc, and factors that modulate it, as well as a technical basis to proceed with in vivo studies of human cerebral zinc metabolism. Collectively, these data will provide a sound platform for exploring the potentially critical role of zinc in the neuropathogenesis of Alzheimer's disease.