Biophysical Studies of Amyloid Formation by Polypeptide Hormones

项目总结 本申请描述了一项跨学科计划，旨在研究人类胰岛淀粉样蛋白的形成。 淀粉样多肽(hIAPP，又称淀粉素)，胰岛淀粉样变性的病原体 糖尿病中的β细胞毒性。由hIAPP形成的淀粉样蛋白是一种公认的病理因素，有助于 2型糖尿病的发展，这是一种在美国已经达到流行程度的衰弱疾病 各州。胰岛淀粉样变性也是胰岛细胞移植失败的主要原因。HIAPP的聚集 最近被认为与1型糖尿病的胰岛β细胞缺乏症和下游心血管疾病有关 糖尿病的并发症。HIAPP通常以一种可溶性多肽激素的形式与胰岛素一起从 胰岛β细胞，并在葡萄糖代谢中发挥适应性作用，包括调节该作用 胰岛素和其他胰腺代谢荷尔蒙。然而，在代谢性疾病中，hIAPP聚集成 细胞毒性构象聚集成淀粉样纤维，在胰岛中以斑块的形式沉积。这一过程 胰岛淀粉样蛋白的形成对β细胞有毒性，并在疾病进展中发挥重要作用。野生型hIAPP 在大多数个体中导致胰岛淀粉样变性，但S20G突变与 患糖尿病的风险。HIAPP的可溶性类似物可作为胰岛素治疗的辅助药物。 糖尿病，特别是1型糖尿病，其β细胞的迅速丧失导致对激素的依赖 替代疗法。可溶性hIAPP类似物也对肥胖症的潜在治疗感兴趣。这个 计划中的研究将解决淀粉样蛋白形成的基本问题，并将为研究策略提供重要的见解。 用于治疗1型和2型糖尿病。我们将应用一种跨学科的蛋白质组合 生物物理学、生物化学和胰岛细胞生物学解决该领域的三个关键问题：1)定义 HIAPP淀粉样蛋白的形成和毒性的测定，包括特定氨基酸侧链的作用 相互作用；2)阐明S20G的侵略性聚集和高度毒性的原因 HIAPP的突变体；3)合理开发和严格测试下一代可溶性类似物 HIAPP。这些研究将确定影响hIAPP淀粉样蛋白形成和胰岛β细胞毒性的分子特征。 他们将确定广泛适用于其他蛋白质聚集性疾病的一般原则，并 淀粉样蛋白形成的机制研究。

PROJECT SUMMARY This application describes an interdisciplinary program designed to study amyloid formation by human islet amyloid polypeptide (hIAPP, also known as amylin), the causative agent of pancreatic islet amyloidosis-induced beta-cell toxicity in diabetes. Amyloid formation by hIAPP is a well-established pathological factor contributing to the development of type 2 diabetes, a debilitating disease that has reached epidemic proportions in the United States. Islet amyloidosis is also a major contributor to islet cell transplantation failure. Aggregation of hIAPP has recently been implicated in islet beta-cell deficiency in type 1 diabetes, and in the downstream cardiovascular complications of diabetes. hIAPP is normally secreted as a soluble polypeptide hormone together with insulin from the pancreatic beta-cells and plays an adaptive role in glucose metabolism, including the regulation of the action of insulin and other pancreatic metabolic hormones. However, in metabolic disease, hIAPP aggregates into cytotoxic conformations that assemble into amyloid fibrils that deposit as plaques in the islets. The process of islet amyloid formation is toxic to beta-cells and plays an important role in disease progression. Wild type hIAPP is responsible for islet amyloidosis in the majority of individuals, but an S20G mutation is linked to an increased risk of diabetes. Soluble analogs of hIAPP are of interest as adjuncts to insulin therapy for the treatment of diabetes, particularly for type 1 diabetes, where the rapid loss of beta-cells results in dependence on hormone replacement therapy. Soluble hIAPP analogs are also of interest for the potential treatment of obesity. The planned studies address fundamental issues in amyloid formation, and will offer important insight into strategies for the treatment of type 1 and type 2 diabetes. We will apply an interdisciplinary combination of protein biophysics, biochemistry, and islet cell biology to address three key issues in the field: 1) defining the determinates of hIAPP amyloid formation and toxicity, including the role of specific amino acid sidechain interactions; 2) elucidating the reasons for the aggressive aggregation and heightened toxicity of the S20G mutant of hIAPP; and 3) the rational development and rigorous testing of next generation soluble analogs of hIAPP. The studies will define the molecular features impacting hIAPP amyloid formation and islet beta-cell toxicity. They will identify general principles that will be broadly applicable to other protein aggregation diseases, and to mechanistic studies of amyloid formation.