Inhibition of Human Islet Amyloid Polypeptide Aggregation

摘要 越来越多的证据表明，胰岛淀粉样多肽的聚集与β细胞有关。 2型糖尿病死亡(T2D)。IAPP是一种由β细胞分泌的37个残基的多肽激素，很容易形成淀粉样蛋白 微米级浓度下的体外纤维。IAPP的聚集体，不溶于淀粉样纤维或可溶于水 低聚物，被发现对β-细胞有毒。抑制IAPP聚集是一种有吸引力的治疗策略 预防β细胞死亡，阻止T2D中糖尿病病情的进展。有趣的是，没有明显的IAPP 在健康个体中观察到聚集体，其中IAPP以mM浓度储存在β细胞颗粒中。 因此，生理条件下的β细胞颗粒天然抑制淀粉样蛋白的聚集。中断 β细胞颗粒的抑制环境可能导致有毒的IAPP聚集体聚集，导致β- T2D中细胞死亡与糖尿病胰岛素缺乏的关系。自然抑制的分子机制 HIAPP聚集性在很大程度上是未知的，这限制了新的治疗方法的设计，这些方法或者 促进或模仿天生的抑制。此外，几种天然产生的小分子多酚 对hIAPP聚集有抑制作用。然而，这些小分子中的许多都含有低水分。 溶解度，这限制了它们的生物利用度和生物分布。对这些物质作用机制的认识 多酚类物质可能有助于设计新的小分子药物，能够抑制hIAPP聚集 药效和溶解度。此外，我们的初步研究将计算机模拟与体外和实验相结合 体内表征表明，第三代聚酰胺胺(PAMAM)树枝状大分子是一种聚合物 纳米粒通常用于药物输送，也能抑制hIAPP的聚集。我们的结果表明 高效负载抗淀粉样蛋白药物和抑制hIAPP的纳米药物研究前景看好 聚合。在这个Mira应用程序中，PI提出了以下三个项目来揭示各种抑制因素 HIAPP聚集机制：1)阐明环境因素对HIAPP聚集的抑制机制 颗粒对IAPP聚集的影响；2)揭示小分子抑制IAPP聚集的机制 多酚；以及3)探索具有更高小分子负载量和抑制性的树枝状纳米颗粒 对hIAPP聚集的影响。PI实验室将把计算建模和实验相结合 表征和验证。计算建模可以帮助弥合时间和长度尺度之间的差距 在实验观察和潜在的分子系统之间，不仅提供了分子洞察力 对实验观察，但也提供了实验可验证的假说。这样的组合 计算和实验相结合的方法可以提高研究效率，缩短发现周期。这个 拟议研究的结果将有助于设计治疗策略，以促进或模仿本地人 抑制(项目1)，具有增强的抗淀粉样蛋白功效的新型小分子抑制剂(项目2)，以及 具有高药物输送和增强的抗聚集性能的工程NPs(项目3)。

Abstract Mounting evidence suggests that the aggregation of islet amyloid polypeptide (IAPP) is associated with β-cell death in type-2 diabetes (T2D). IAPP, a 37-residue peptide hormone secreted by β-cells, readily forms amyloid fibrils in vitro at µM concentrations. The aggregates of IAPP, either insoluble amyloid fibrils or soluble oligomers, are found toxic to β-cells. Inhibition of IAPP aggregation is an attractive therapeutic strategy to prevent β-cell death and stop the progression of diabetic conditions in T2D. Interestingly, no apparent IAPP aggregates are observed in healthy individuals where IAPP is stored in β-cell granules at mM concentrations. Therefore, physiological conditions of β-cell granules natively inhibit amyloid aggregation of IAPP. Disruption of the inhibitive environment of β-cell granules may lead to the accumulation of toxic IAPP aggregates, causing β- cell death and the diabetic condition of insulin deficiency in T2D. Molecular mechanisms of the native inhibition of hIAPP aggregation are largely unknown, which limit the design of novel therapeutic approaches that either promote or mimic the native inhibition. In addition, several naturally-occurring small-molecule polyphenols displayed inhibitory effects on hIAPP aggregation. However, many of these small molecules have low water solubility, which limits their bioavailability and biodistribution. Knowledge of the mechanism of action of these polyphenols may help design de novo small-molecule drugs that can inhibit hIAPP aggregation with higher efficacy and solubility. Further more, our preliminary studies combining in silico modeling with in vitro and ex vivo characterization indicated that the generation-3 polyamidoamin (PAMAM) dendrimer, a polymeric nanoparticle commonly used for drug delivery, could also inhibit hIAPP aggregation. Our results pointed to a promising nanomedicinal approach for both efficient loading of ant-amyloid drug and inhibitory effect on hIAPP aggregation. In this MIRA application, the PI proposes the following three projects to uncover various inhibition mechanisms of hIAPP aggregation: 1) to delineate the inhibitive mechanism of the environmental elements of granules on IAPP aggregation; 2) to uncover the inhibition mechanism of hIAPP aggregation by small-molecule polyphenols; and 3) to explore dendritic nanoparticles with increased small-molecule loading and inhibitive effects on hIAPP aggregation. The PI lab will combine computational modeling with experimental characterization and validation. Computational modeling can help bridge the gaps of time and length scales between experimental observations and the underlying molecular systems, providing not only molecular insight to experimental observations but also offering experimentally-testable hypotheses. Such a combined computational and experimental approach can improve research efficiency and shorten discovery cycle. The outcome of the proposed studies will help design therapeutic strategies to either promote or mimic the native inhibition (Project 1), novel small-molecule inhibitors with enhanced anti-amyloid efficacy (Project 2), and engineered NPs with both high drug delivery and enhanced anti-aggregation properties (Project 3).