Extracellular Zinc Buffering and A-beta Oligomerization

细胞外锌缓冲和 A-β 寡聚化

• 批准号: 8046593
• 负责人: Guido Faas
• 金额: $ 18.94万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-03-15 至 2013-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8046593
• 关键词: Accounting; Affect; Alzheimer' s Disease; Amyloid; Animal Model; Area; Astrocytes; Binding; Binding Proteins; Biophysical Process; Brain; Buffers; Calcium-Binding Proteins; Cerebral cortex; Chelating Agents; Computer Simulation; Dementia; Development; Drug Design; Economics; Elderly; Equilibrium; Event; Extracellular Space; Frequencies; Glutamates; Human; In Vitro; Inflammatory Response; Ions; Kinetics; Knock-out; Lead; Limbic System; Measurement; Measures; Metal Ion Binding; Metals; Methods; Modeling; Monitor; Nature; Neurodegenerative Disorders; Neuroglia; Neurons; Oligonucleotides; Pathway interactions; Pattern; Peptides; Pharmaceutical Preparations; Physiological; Play; Presynaptic Terminals; Prevention; Production; Proteins; Reactive Oxygen Species; Research; Rest; Role; Senile Plaques; Signal Transduction; Simulate; Solutions; Symptoms; Synapses; Synaptic Cleft; System; Techniques; Testing; Time; Toxic effect; Ultraviolet Rays; Vesicle; Zinc; amyloid pathology; chelation; drug development; effective therapy; extracellular; flash photolysis; human MT3 protein; insight; millisecond; mouse model; prevent; self assembly; tau Proteins; theories

DESCRIPTION (provided by applicant): Alzheimer's disease (AD) is the most common type of dementia and it is the major cause of dementia affecting the elderly, accounting for 60-80% of all dementia cases. Although the mechanisms of AD are not well understood it is known that AD is a proteopathy leading to intracellular accumulation of tau protein and extracellular amyloid 2 (Ab) aggregates (senile plaques). When synaptically released Ab oligomerizes, and eventually aggregates, it leads to neuronal damage and an inflammatory response in glial cells through either direct toxicity and/or production of reactive oxygen species. It is not very well understood what triggers Ab oligomerization and aggregation in AD. One of the theories is the "metal hypothesis of AD" which posits that extracellular metal ions, especially synaptically excreted Zn2+, instigate the Ab oligomerization and aggregation leading to the formation of senile plaques. Despite much progress supporting the metal hypothesis of AD, this idea remains a debated issue, partly because there is no adequate information on the binding and aggregation events at the timescale of synaptically released Zn2+. Clearly, a better understanding of the temporal patterns of Zn2+ signals is required together with a thorough insight into how these signals might trigger pathological oligomerization of Ab. This becomes especially important if there is a specific Zn2+ concentration window or a specific temporal pattern of the Zn2+ signals that would allow the formation of soluble oligomers, which are thought to be the most toxic, but not their aggregation into plaques which possibly protect against toxicity. In spite of enormous efforts in research, presently there is no treatment available for AD. It has been shown that chelation of Zn2+ can ameliorate plaque formation in animal models of AD, and accordingly, Zn2+ chelators have been suggested as a potential treatment for AD by preventing Ab oligomerization. Modulators of Zn2+ buffering pathways also hold promise for drug development in AD. Understanding the biophysical processes underlying the oligomerization of Ab as well as insights into the temporal patterns of Zn2+ signals that drive oligomerization are essential for developing such drugs. We have devised an ultra-fast in vitro kinetic measurement technique of Ca2+- binding to calcium binding proteins following flash photolysis of caged Ca2+ and created a compartmental kinetic model that resolved for the first time the cooperative nature of Ca2+ binding. This technique will be adapted to measure the fast Zn2+ binding kinetics by uncaging Zn2+ in the presence of Ab while optically monitoring Zn2+ binding dynamics. The same will be done to measure the Zn2+ binding dynamics of the Zn2+-binding protein metallothionein-3 (MT-3) which is enriched at Zn2+ releasing synapses. Our approach allows the unprecedented possibility to simulate extracellular Zn2+ signals as they are thought to occur at synapses. Studying the dynamics of Zn2+ binding to Ab and to other proteins under conditions resembling those at synapses will provide a first direct distinction between the physiological and pathological roles of Zn2+ in Ab oligomerization, resulting in the potential development of new and highly effective drugs for AD. PUBLIC HEALTH RELEVANCE: It has been shown that reducing zinc (Zn2+) release in the brain can ameliorate plaque formation in animal models of Alzheimer's disease (AD). Accordingly, modulators of extracellular Zn2+ levels have been suggested as potentially an effective treatment for AD by preventing the formation of senile plaques. This project will determine when naturally occurring Zn2+ signals drive Ab oligomerizatoin which underlies formation of senile plaques and many other the symptoms of AD. With the acquired insight it should be possible to design drugs that specifically target pathological Zn2+ signals that may cause AD while minimally disturbing the Zn2+ signals necessary for normal brain functioning.

描述（申请人提供）：阿尔茨海默病（AD）是最常见的痴呆症类型，也是影响老年人痴呆症的主要原因，占所有痴呆症病例的 60-80%。尽管 AD 的机制尚不清楚，但已知 AD 是一种蛋白质病，导致 tau 蛋白和细胞外淀粉样蛋白 2 (Ab) 聚集（老年斑）在细胞内积聚。当突触释放的抗体寡聚并最终聚集时，它会通过直接毒性和/或活性氧的产生，导致神经元损伤和神经胶质细胞的炎症反应。目前尚不清楚是什么触发 AD 中抗体寡聚和聚集。其中一种理论是“AD金属假说”，该假说认为细胞外金属离子，特别是突触分泌的Zn2+，会促使抗体寡聚和聚集，导致老年斑的形成。尽管支持 AD 的金属假说取得了很大进展，但这一想法仍然是一个有争议的问题，部分原因是没有关于突触释放 Zn2+ 时间尺度上的结合和聚集事件的足够信息。显然，需要更好地了解 Zn2+ 信号的时间模式，并深入了解这些信号如何触发抗体的病理性寡聚化。如果存在特定的 Zn2+ 浓度窗口或 Zn2+ 信号的特定时间模式，这将允许形成可溶性低聚物（被认为是毒性最大的），但不会聚集成可能防止毒性的斑块，则这一点变得尤为重要。尽管在研究方面付出了巨大的努力，但目前还没有针对 AD 的治疗方法。研究表明，Zn2+ 螯合可以改善 AD 动物模型中斑块的形成，因此，Zn2+ 螯合剂被建议通过防止 Ab 寡聚化作为 AD 的潜在治疗方法。 Zn2+ 缓冲途径的调节剂也为 AD 药物开发带来了希望。了解 Ab 寡聚化背后的生物物理过程以及对驱动寡聚化的 Zn2+ 信号的时间模式的深入了解对于开发此类药物至关重要。我们设计了一种超快速体外动力学测量技术，用于在笼中 Ca2+ 发生闪光光解后，测量 Ca2+- 与钙结合蛋白的结合，并创建了一个隔室动力学模型，首次解析了 Ca2+ 结合的协同性质。该技术将适用于通过在 Ab 存在的情况下释放 Zn2+ 来测量快速 Zn2+ 结合动力学，同时光学监测 Zn2+ 结合动力学。同样可以测量 Zn2+ 结合蛋白金属硫蛋白-3 (MT-3) 的 Zn2+ 结合动力学，该蛋白在 Zn2+ 释放突触处富集。我们的方法提供了前所未有的可能性来模拟细胞外 Zn2+ 信号，因为它们被认为发生在突触处。在类似于突触的条件下研究 Zn2+ 与 Ab 和其他蛋白质结合的动态，将首次直接区分 Zn2+ 在 Ab 寡聚化中的生理和病理作用，从而有可能开发出新的高效 AD 药物。 公共健康相关性：研究表明，减少大脑中锌 (Zn2+) 的释放可以改善阿尔茨海默病 (AD) 动物模型中的斑块形成。因此，细胞外 Zn2+ 水平调节剂被认为可以通过预防老年斑的形成来有效治疗 AD。该项目将确定自然发生的 Zn2+ 信号何时驱动抗体寡聚化，而抗体寡聚化是老年斑形成和许多其他 AD 症状的基础。凭借所获得的见解，应该可以设计出专门针对可能导致 AD 的病理性 Zn2+ 信号的药物，同时最大限度地减少对正常大脑功能所需的 Zn2+ 信号的干扰。