Biophysical Studies of Amyloid Formation by Polypeptide Hormones

描述（由申请人提供）：淀粉样蛋白沉积发生在至少25种不同的人类疾病中。本项目的重点是胰岛淀粉样蛋白多肽（IAPP, Amylin）的淀粉样蛋白形成，该激素负责2型糖尿病胰岛淀粉样蛋白的形成。IAPP通常作为可溶性多肽与胰岛素一起分泌，但在2型糖尿病中通过一种未知的机制聚集形成细胞外胰岛淀粉样蛋白。胰岛淀粉样蛋白，或其形成过程，对细胞有毒，并有助于2型糖尿病的病理。IAPP引起的淀粉样蛋白形成最近被证明是胰岛细胞移植的一个主要复杂因素。糖尿病在美国已达到流行病的程度，并正在成为发展中国家的主要健康威胁。关于IAPP形成淀粉样蛋白的机制，以及在其形成过程中产生的有毒物质的性质，我们所知相对较少。本研究将(1)通过IAPP确定淀粉样蛋白的形成机制；（II）研究被认为与早发性糖尿病有关的IAPP突变的影响；（III）确定淀粉样蛋白组装过程中毒性最强的物种，并确定它们的构象性质；（IV）严格检验加速淀粉样蛋白形成降低IAPP诱导的细胞毒性的假设。该研究将为治疗2型糖尿病和预防胰岛移植后衰竭提供新思路。吸取的经验教训也将有助于设计更多可溶的IAPP变体来治疗1型糖尿病。实验生物物理学、生物化学和细胞生物学的跨学科结合将用于解决这些问题。正在开发的方法有望广泛适用，并将有助于更好地控制其他疾病中的淀粉样蛋白形成。将实现五个具体目标。第一个是通过IAPP研究淀粉样蛋白的形成机制。第二个目标是研究人类IAPP自然突变体增强淀粉样蛋白形成的基础。第三个目标将使用高分辨率方法询问IAPP在淀粉样蛋白形成过程中填充的有毒中间体的构象特性，而第四个目标将进行有毒和无毒IAPP抑制剂复合物的比较研究。最终目的是测试一种防止IAPP毒性的新策略。

DESCRIPTION (provided by applicant): Amyloid deposition occurs in at least twenty five different human diseases. This project is focused on amyloid formation by Islet Amyloid Polypeptide (IAPP, Amylin), the hormone responsible for pancreatic islet amyloid in type 2 diabetes. IAPP is normally secreted as a soluble polypeptide together with insulin, but aggregates via an unknown mechanism in type 2 diabetes to form extracellular islet amyloid. Islet amyloid, or the process of its formation, is toxic to ¿-cells and contributes to the patholog of type 2 diabetes. Amyloid formation by IAPP has been recently shown to be a major complicating factor in islet cell transplantation. Diabetes has reached epidemic proportions in the United States and is emerging as a major health threat in the developing world. Relatively little is known about the mechanism of amyloid formation by IAPP or about the nature of the toxic species generated during its formation. The research will (I) determine the mechanism of amyloid formation by IAPP; (II) examine the effects of a mutation in IAPP which has been proposed to be linked to early onset diabetes; (III) define the most toxic species populated during amyloid assembly and define their conformational properties; (IV) critically test the hypotheses that accelerating amyloid formation reduces IAPP induced cytotoxicity. The research will provide insight into strategies for the treatment of type 2 diabetes and for the prevention of islet graft failure after transplantation. The lessons learned will also aid in the design of more soluble variants of IAPP to treat type 1 diabetes. An interdisciplinary combination of experimental biophysics, biochemistry and cell biology will be used to address these issues. The methods being developed are expected to be broadly applicable and will aid efforts to better control amyloid formation in other diseases. Five specific aims will be carried out. The first involves studies of the mechanism of amyloid formation by IAPP. The second aim will examine the basis for enhanced amyloid formation by a natural mutant of human IAPP. The third aim will interrogate the conformational properties of toxic intermediates populated during amyloid formation by IAPP using high resolution methods, while the fourth aim will conduct comparative studies of toxic and non-toxic IAPP inhibitor complexes. The final aim will test a new strategy for preventing IAPP toxicity.