A multi-scale data-driven model of the Abeta pore function and Ca2+ toxicity in Alzheimer's disease

阿尔茨海默病（AD）是一种慢性神经退行性疾病，其导致广泛的认知功能进行性恶化并最终死亡。淀粉样β（Aβ）肽Aβ40、Aβ42和Aβ43是AD发病机制中的关键因子。最近的研究结果表明，Aβ寡聚体形式的细胞外和细胞内蓄积而不是大的不溶性聚集体可能是病理学罪魁祸首，并且它们的毒性是通过在质膜（PM）中形成毒性Ca2+渗透孔而介导的胞质Ca2+不受控制的升高。然而，缺乏关于不同Aβ孔类型的功能以及PM的哪一个小叶更容易形成孔的详细信息。这些孔在其功能特性中显示出显著的多样性和时间依赖性变化。此外，由于三种类型的肽孔之间的药理学比较缺乏。Aβ孔的高度异质性和动态性对通过传统的单通道方法研究其致病机制提出了极大的挑战。我们的目标是使用多尺度数据驱动建模结合分辨率低至单通道水平的先进成像技术，填补AD中Aβ介导的Ca2+信号传导中断理解的关键空白。使用我们的光学膜片钳技术，我们将监测和比较由细胞外和细胞内Aβ寡聚体形成的数百个Aβ孔的门控特性和时间依赖性演变。我们将测量和比较三种Aβ孔类型的电导特性、门控动力学和时间依赖性演变。我们建议在相同条件下对Aβ40、Aβ42和Aβ43孔进行平行实验，以：（1）阐明和比较它们在各种调节剂（包括锌、铝和铜）存在下的功能，（2）比较Aβ孔阻断剂（如NA 7和贝沙罗汀）的作用，（3）天然酚（包括姜黄素、橄榄苦苷和白藜芦醇）如何影响它们的形成和进化，以及（4）膜成分包括胆固醇和磷脂酰丝氨酸的变化如何影响Aβ孔的功能。在实验数据的推动下，我们将为每种孔隙类型的不同变体（基于峰值渗透率）开发特定模型，然后将这些模型组合成一个统一的模型，包括每种Aβ孔隙类型的快速（毫秒）门控动力学和缓慢（数十分钟和小时）演变。我们将把调节剂和PM组分的作用纳入每个模型中，并测试不同调节剂的同时存在如何影响不同细胞膜中Aβ孔的行为？我们将使用这些模型进行长时间模拟（数小时或数天），以更好地了解孔如何演变以及它们如何作为时间、空间排列、运动性和Aβ40、Aβ42和Aβ43插入PM和不同细胞内细胞器（包括ER、线粒体和溶酶体）的膜时的比例对总体Ca2+毒性的贡献。

Alzheimer's disease (AD) is a chronic neurodegenerative disorder that leads to progressive deterioration in a broad range of cognitive functions and finally death. Three amyloid beta (Aβ) peptides, Aβ40, Aβ42, and Aβ43 have been implicated as a key factors in the pathogenesis of AD. Recent findings indicate that extra- and intracellular accumulations of oligomeric forms of Aβ rather than large insoluble aggregates are the likely pathological culprits, and that their toxicity is mediated through uncontrolled elevation of cytosolic Ca2+ by formation of toxic Ca2+-permeable pores in the plasma membrane (PM). Yet, detailed information about the function of different Aβ pore types and which leaflet of the PM is more susceptible to pore formation are lacking. These pores have shown significant diversity and time dependent changes in their functional properties. Moreover, pharmacological comparisons between pores due to the three types of peptides are lacking. The highly heterogeneous and dynamic nature of Aβ pores poses extreme challenges in investigating their pathogenic mechanisms through traditional single channel approaches. Our goal is to fill a critical void in the understanding of Aβ-mediated Ca2+ signaling disruptions in AD using multi-scale data-driven modeling in conjunction with advanced imaging techniques having a resolution down to single channel level. Using our optical patch clamp technique, we will monitor and compare the gating properties and time- dependent evolution of hundreds of Aβ pores formed by extra- and intracellular Aβ oligomers. We will measure and compare the conductance properties, gating kinetics, and time-dependent evolution of the three Aβ pore types. We propose to perform parallel experiments on Aβ40, Aβ42, and Aβ43 pores in identical conditions to: (1) elucidate and compare their function in the presence of various modulators including Zinc, Aluminum, and Copper, (2) compare the effects of Aβ pore blockers such as NA7 and Bexarotene, (3) how natural phenols including Curcumin, Oleuropein, and Resveratrol affect their formation and evolution, and (4) how changes in membrane components including cholesterol and phosphatidylserine affect the function of Aβ pores. Driven progressively by experimental data, we will develop specific models for different variants (based on peak permeability) of each pore type, followed by combining these models into a unified model encompassing both the fast (milliseconds) gating kinetics and slow (tens of minutes and hours) evolution of each Aβ pore type. We will incorporate the effect of modulators and PM components into each model and test how the concurrent presence of different modulators affect Aβ pores' behavior in different cell membranes? We will use these models to perform long simulations (many hours or days) to better understand how pores evolve and how they contribute to overall Ca2+ toxicity as a function of time, spatial arrangement, motility, and ratio of Aβ40, Aβ42, and Aβ43 when inserted into PM and membranes of different intracellular organelles including ER, mitochondria, and lysosomes.