Membrane catalyzed amyloid formation in diabetes studied with 2D IR spectroscopy

描述（由申请人提供）：2型糖尿病是美国最流行的疾病之一，造成超过2080万人患病，并在该国某些地区以流行病的速度蔓延。2型糖尿病的关键诊断是胰腺中淀粉样纤维的存在。这些纤维由人胰岛淀粉样多肽（hIAPP）组成，许多体外和体内研究将其与疾病联系起来。即使如此，hIAPP抑制胰腺2细胞功能和胰岛素产生的机制仍不清楚。越来越多的证据表明，hIAPP与细胞膜相互作用是细胞功能障碍的原因，而不是纤维本身。这一假说的一个证据是，脂质囊泡催化纤维形成，并在这样做时变得可渗透和泄漏。因此，似乎理解疾病机制需要在膜缔合、折叠和纤维形成期间对hIAPP进行结构表征。然而，由于该机制是动力学的，并涉及膜，传统的结构方法，如NMR是难以应用。因此，几乎所有的实验结构信息都来自圆二色性测量，它只提供了肽结构的基本表征。甚至不确定肽的哪一部分与膜结合。考虑到了解的重要性，hIAPP与脂质膜的结构变化，我们建议使用FTIR和二维红外光谱，结合1- 13 C = 18 O同位素标记，产生特定位点的结构信息hIAPP在脂质囊泡的存在下折叠的动力学。我们将获得残基水平的信息肽协会与膜，插入和方向，二级结构的形成，并测试是否在膜孔的形式。结构形成的动力学将有助于揭示淀粉样纤维形成的催化机制。我们试图获得一个详细的结构表征的hIAPP膜催化动力学，这是目前不可能与其他技术。用2D IR光谱研究糖尿病中膜催化淀粉样蛋白形成用2D IR光谱研究糖尿病中膜催化淀粉样蛋白形成 相关性 2型糖尿病的一个明确诊断是胰腺中存在淀粉样蛋白沉积。最近 研究表明，引起这种疾病的不是沉积物本身，而是它们的形成。 什么时候接触胰腺？细胞这项提案的目的是为了更好地了解这种疾病 通过从结构上表征细胞膜如何催化淀粉样蛋白沉积物的形成， 从而提供有助于开发阻止疾病的药剂的基本知识。

DESCRIPTION (provided by applicant): Type 2 diabetes is one of the most prevalent diseases in the United States, inflicting more than 20.8 million people and expanding at epidemic rates in some areas of the country. The key diagnostic of Type 2 diabetes is the presence of amyloid fibers in the pancreas. These fibers are composed of the human islet amyloid polypeptide (hIAPP) and many in vitro and in vivo studies have linked them to the disease. Even so, the mechanism by which hIAPP inhibits pancreatic 2-cell function and insulin production is not understood. A growing body of evidence points to hIAPP interacting with the cell membrane as the cause of cell dysfunction rather than the fibers themselves. One piece of evidence for this hypothesis is that lipid vesicles catalyze fiber formation and in doing so become permeable and leak. Thus, it appears that understanding the disease mechanism requires structural characterization of hIAPP during membrane association, folding, and fiber formation. However, since the mechanism is both kinetic and involves membranes, conventional structural approaches such as NMR are difficult to apply. As a result, almost all experimental structural information comes from circular dichroism measurements, which provide only a rudimentary characterization of the peptide structure. It is not even definitively known which part of the peptide associates with the membrane. Considering the importance of understanding the structural changes of hIAPP with lipid membranes, we propose to use FTIR and 2D IR spectroscopy, in conjunction with 1-13C=18O isotope labeling, to yield site-specific structural information on hIAPP during the kinetics of folding in the presence of lipid vesicles. We will gain residue-level information on peptide association with the membrane, insertion and orientation, secondary structure formation, and test whether pores in the membrane form. The kinetics of structure formation will help reveal the catalytic mechanism for amyloid fiber formation. We seek to obtain a detailed structural characterization of hIAPP membrane catalyzed kinetics that is not currently possible with other techniques. Membrane catalyzed amyloid formation in diabetes studied with 2D IR spectroscopy Membrane catalyzed amyloid formation in diabetes studied with 2D IR spectroscopy Relevance A clear diagnostic of Type 2 diabetes is the presence of amyloid deposits in the pancreas. Recent research suggests that it is not the deposits themselves that cause the disease, but rather their formation when in contact with pancreatic ?-cells. The aim of this proposal is to better understand the disease mechanism by structurally characterizing how cell membranes catalyze the formation of amyloid deposits, thereby providing basic knowledge that could help in developing pharmaceutical agents to stop the disease.