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（IAPP）的聚集与β细胞 2型糖尿病（T2 D）死亡。IAPP是β细胞分泌的一种37个氨基酸残基的肽类激素， 在体外以μM浓度的纤维。IAPP的聚集体，无论是不溶性淀粉样纤维还是可溶性淀粉样纤维， 寡聚体被发现对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细胞死亡并阻止T2 D中糖尿病状况的进展。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，β细胞颗粒的生理条件天然抑制IAPP的淀粉样蛋白聚集。破坏 β-细胞颗粒的抑制性环境可能导致毒性IAPP聚集体的积累，引起β- 细胞死亡和T2 D中胰岛素缺乏的糖尿病状况。天然抑制的分子机制 hIAPP聚集的机制在很大程度上是未知的，这限制了新的治疗方法的设计， 促进或模仿天然抑制。此外，几种天然存在的小分子多酚 显示对hIAPP聚集的抑制作用。然而，这些小分子中的许多具有低水 溶解性，这限制了它们的生物利用度和生物分布。了解这些药物的作用机制 多酚可能有助于设计从头小分子药物，可以抑制hIAPP聚集， 功效和溶解性。此外，我们的初步研究结合计算机模拟和体外实验， 体内表征表明，第3代聚酰胺胺（PAMAM）树枝状聚合物，一种聚合物， 通常用于药物递送的纳米颗粒也可以抑制hIAPP聚集。我们的研究结果表明， 一种有前途的纳米医学方法，用于有效装载抗淀粉样蛋白药物和抑制hIAPP 聚合来在这个MIRA应用程序中，PI提出了以下三个项目，以揭示各种抑制 hIAPP聚集的机制：1）描述环境因素对hIAPP聚集的抑制机制， 2）揭示小分子化合物对hIAPP聚集的抑制机制 多酚;和3）探索具有增加的小分子负载和抑制性的树枝状纳米颗粒 对hIAPP聚集的影响。PI实验室将联合收割机计算建模与实验 表征和验证。计算建模可以帮助弥合时间和长度尺度的差距 实验观察和基础分子系统之间的联系，不仅提供了分子洞察力， 实验观察，但也提供实验验证的假设。这样的组合 计算和实验的方法可以提高研究效率，缩短发现周期。的 所提出的研究结果将有助于设计治疗策略，以促进或模仿天然的 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），和 具有高药物递送和增强的抗聚集特性的工程化NP（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).