Fibrillogenesis pathways in diabetes and renal diseases

描述(申请人提供)：可溶蛋白质转化为淀粉样纤维是包括阿尔茨海默氏症、亨廷顿氏症和II型糖尿病在内的许多临床疾病的特征。在每种疾病中，前体蛋白都有不同的一级和三级结构。然而，生成的纤维在组织学和超微结构水平上非常相似。纤维形成动力学类似于结晶，因为存在一个较长的滞后阶段，在该阶段中纤维是不可检测的。这之后是向纤维态的协同转变。有趣的是，在滞后期采样的纤维态和中间态都被鉴定为细胞毒性。因此，所有这些紊乱的核心是需要确定构象变化的分子基础。 这项建议的总体目标是确定两个医学相关系统中淀粉样蛋白转化的分子基础。首先是胰岛淀粉样多肽(IAPP)，这是一种37个残基的多肽荷尔蒙，由胰腺的b细胞与胰岛素共同分泌。在II型糖尿病患者中，它以淀粉样蛋白的形式沉积，导致b细胞死亡。其次，需要透析治疗的肾脏疾病会导致关节中b-2微球蛋白(B2M)的沉积，从而引起各种骨骼病理。在这两个系统中，聚集在一起的都是野生型、未经修饰的蛋白质形式。我们的方法是确定这些蛋白质在体内环境中可能发生的变化，并确定这些变化对这些系统的折叠和纤维形成的分子影响。在LAPP中，我们的团队最近报告了一个专有中间体和两个成核过程的存在。第一个主要目标是确定与这些现象相关的构象和寡聚变化。此外，我们还确定LAPP的纤维形成显著地受到胰岛素和分泌颗粒的脂质双层的干扰。由于这两种成分在糖尿病患者中都受到干扰，我们将确定这些影响的分子基础。在Beta2m中，我们的团队最近发现了B2M和铜(11)之间的一种新的相互作用，这种相互作用可以在血液透析治疗过程中的条件下独特地引起淀粉样纤维的成核。我们的第二个主要目标是确定二价诱导淀粉样变性的结构和能量基础。我们的目标将通过联合使用诱变、光学、核磁共振和氘交换技术来阐明蛋白质折叠和纤维形成途径的扰动。

DESCRIPTION (provided by applicant): The conversion of soluble proteins into amyloid fibers is a feature of a number of clinical disorders including Alzheimer's, Huntington's and type II diabetes. In each medical disorder, the precursor protein has distinct primary and tertiary structure. However, the resultant fibers are remarkably similar at the histological and ultrastructural level. Fiber formation kinetics are similar to crystallization in that there exists a prolonged lag phase in which fiber is undetectable. This is followed by a cooperative transition to the fibrous state. Interestingly, both the fibrous state, and the intermediate states sampled during the lag phase have been identified as cytotoxic. Central to all these disorders, therefore, is the need to identify the molecular basis of conformational change. The overall goal of this proposal is to determine the molecular basis for amyloid conversion in two medically relevant systems. First, islet amyloid polypeptide(IAPP), a 37 residue peptide hormone that is cosecreted with insulin by the b-cells of the pancreas. In type II diabetics, it deposits as amyloid resulting in b-cell death. Second, renal diseases which necessitate treatment by dialysis result in the deposition of b-2 microglobulin (b2m) in the joints giving rise to a variety of skeletal pathologies. In both of these systems, it is wild-type, unmodified forms of the protein which aggregate. Our approach is to identify plausible changes in the in vivo environment of theses proteins and to determine the molecular impact of these changes on the folding and fibrillogenesis of these systems. In lAPP, our group recently reported the existence of an obligate intermediate and two nucleation processes. The first major aim is to determine the conformation and oligomeric changes associated with these phenomena. Furthermore, we have also determined that fibrillogenesis of lAPP is significantly perturbed by both insulin and the lipid bilayer of the secretory granule. As both of these components are perturbed in diabetics, we will determine the molecular basis for these effects. In Beta2m, our group recently discovered a novel interaction between b2m and Cu(ll) which can uniquely give rise to the nucleation of amyloid fibers under conditions present during hemodialysis therapy. Our second major aim is to determine the structural and energetic basis for divalent induced amyloidosis. Our aims will be met by combined use of mutagenesis, optical, NMR and deuterium exchange techniques to elucidate the perturbation of protein folding and fibrillogenesis pathways.