胞外β淀粉样多肽（Aβ）聚集体通过多个途径导致脑内胰岛素信号通路异常，这是引发阿尔茨海默病（AD）的主要病因之一。作为结合蛋白，金属硫蛋白3（MT3）能调制Aβ的聚集，进而影响其在胰岛素信号通路中的毒性作用。但是，目前Aβ的聚集机制尚不完善，MT3的调制作用研究更是空白。针对上述问题，本项目拟结合实验与理论计算，确定Aβ与MT3作用的结合位点和结合常数，揭示溶液中和磷脂膜上MT3调制Aβ聚集的分子机制；通过评估膜通透性和电学性质，建立Aβ聚集体诱导膜损伤的分子机制。同时，研究Aβ与胰岛素信号通路相关蛋白（IR、IDE、IRS、PI3K等）的作用，确认MT3对络合物结构和生物功能的影响；通过SD大鼠海马神经元毒性研究，建立“Aβ聚集体—神经毒性”之间的构效关系。最终完善MT3调制Aβ聚集和脑内胰岛素信号通路异常的分子模型，阐明MT3作为结合蛋白的神经保护机制，为AD的病理研究提供理论指导。

Alzheimer’s disease (AD) is fundamentally a metabolic disease with substantial and progressive responsiveness to insulin stimulation. Amyloid-beta peptide (Aβ) is the main constituent of the senile plaques in the brains of AD patients, produced as soluble protein and can be converted into aggregates (such as oligomers and fibrils). Growing evidence supports the concept that the etiology of AD is the brain insulin resistance induced by the binding events between Aβ aggregates and insulin signaling proteins or membranes. Metallothionein-3 (MT3), which is especially enriched in the central nervous system, is capable of modulating the aggregation of Aβ and Aβ-induced toxicity. However, the Aβ aggregation mechanism remains debatable and the modulation effect from MT3 is unknown. In this proposal, the central theme is the study of MT3-involved Aβ aggregation and its effect on aberrant brain insulin signaling. Specifically, the binding sites and the binding constants of Aβ to MT3 will be confirmed. The aggregation of Aβ in the presence of MT3 will be investigated respectively in solution and membrane/solution interface, to gain insight into the interplay between MT3-involved aggregation and the role of aggregates in membrane damage. Meanwhile, the interations of Aβ and insulin signaling proteins (IR, IDE, IRS, PI3K) will be investigated. A major emphasis will be placed on the understanding of the structure-function/protein interactions of Aβ aggregates. Finally, cytotoxicity of the Aβ aggregates will be studied on hippopotamus neurons of SD rats. We envision that a comprehensive description about the fundamental aspect of MT3-involved Aβ/protein and Aβ/membrane interactions, as well as the related neurotoxicity of the various aggregates, will evolve from our project. Such information will consolidate the understanding of the aggregation properties of Aβ and their involvements in aberrant brain insulin signaling in AD. It will also provide insight into animal model studies and clinical assays.