Degenerative and Dementing Diseases of Aging

描述（由申请人提供）：本申请包括四个科学项目和四个核心，我们建议继续研究由人类朊病毒疾病引起的神经变性，其中最常见的是散发性CJD。朊病毒似乎仅由PrPSc分子组成，而PrPSc分子是通过一个鲜为人知的过程从PrPc前体衍生而来的。本文描述的研究旨在定义PrPSc的结构，表征小分子与PrPc和PrPSc的相互作用，并剖析控制不同人类朊病毒株传播的分子事件。在项目1中，我们建议研究多金属氧酸盐（pom）与PrPSc的相互作用。POM磷钨酸盐阴离子[PW12O40] （PTA）特异性地与PrPSc结合，但不与PrP结合。POMs是一大类具有刚性多面体结构的无机金属氧化物团簇，在尺寸、形状和电荷密度上表现出很大的变化。在Project 2中，我们拟对导致遗传性朊病毒疾病的55个残基MoPrP（89-143,P101L）肽、已知形成淀粉样原纤维的20个分子量PrP（106-126）肽以及纯化的截断（PrP 27-30）和全长PrPSc进行纤维衍射研究，这两种蛋白在野生型动物中都具有传染性。在Project 3中，我们拟对引起sCJD的朊病毒进行研究。这些研究是可能的，因为我们最敏感的表达人/鼠嵌合PrP的Tg小鼠系在接种sCJD朊病毒后约80天内死亡。对这些Tg小鼠体内的人类朊病毒进行相对快速的生物测定，使得测量从死亡的sCJD患者身上收集的整个大脑、外周器官和体液中的朊病毒滴度成为可能。我们还建议建立sCJD和变型(v) CJD的豚鼠模型。在Project 4中，我们计划发现新的结合并稳定人类PrPc的配体。我们还计划确定这些配体是否抑制HuPrPc向HuPrPSc的转化。使用虚拟筛选方法，大型有机分子库将与已知的HuPrPc结构对接。高分化合物将进行生物物理结合测试，控制抗淀粉样蛋白抑制剂容易产生的非特异性抑制。所有拟议研究的最终目标是确定人类朊病毒形成的分子事件，以便开发治疗人类朊病毒疾病的疗法。相关性：朊病毒是一种感染性蛋白，可导致人类和动物的年龄依赖性神经变性。朊病毒蛋白（PrPSc）的可选折叠异构体在人类和动物大脑中的积累是包括克雅氏病（CJD）在内的朊病毒疾病的标志。朊病毒疾病总是致命的，没有有效的治疗方法。克雅氏病药物的成功开发将对其他年龄依赖性神经退行性疾病（包括阿尔茨海默病）的治疗产生重要影响。

DESCRIPTION (provided by applicant): In this application comprising four scientific projects and four-cores, we propose to continue our studies focused on neurodegeneration caused by human prion diseases, the most common of which is sporadic (s) CJD. Prions seem to be composed solely of PrPSc molecules, which are derived from a precursor PrPc by a poorly understood process. The studies described here are aimed at defining the structure of PrPSc, characterizing the interactions of small molecules with both PrPc and PrPSc and dissecting the molecular events governing the propagation of different human prion strains. In Project 1, we propose to study the interactions of polyoxometalates (POMs) with PrPSc. The POM phosphotungstate anion [PW12O40] (PTA) binds specifically to PrPSc, but not to PrP. POMs are a large class of inorganic metal oxide clusters with rigid polyhedral structures displaying substantial variations in size, shape, and charge density. In Project 2, we propose to carry out fiber diffraction studies of the 55-residue MoPrP(89-143,P101L) peptide that causes inherited prion disease, a 20 mer wt PrP(106-126) peptide known to form amyloid fibrils as well as purified truncated (PrP 27-30) and full-length PrPSc, both of which are infectious in wild-type animals. In Project 3, we propose to study the prions causing sCJD. These studies are possible because our most sensitive Tg mouse line expressing chimeric human/mouse PrP succumbs to disease in ~80 days after inoculation with sCJD prions. Relatively rapid bioassays of human prions in these Tg mice make it practical to measure the titers of prions throughout brain as well as in peripheral organs and body fluids collected from dead sCJD patients. We also propose to develop guinea pig models of sCJD and variant (v) CJD. In Project 4, we propose to discover new ligands that bind to and stabilize human PrPc. We also plan to determine whether such ligands inhibit the conversion of HuPrPc into HuPrPSc. Using a virtual screening approach, large libraries of organic molecules will be docked against the known structure of HuPrPc. High-scoring compounds will be tested for binding biophysically, controlling for non-specific inhibition to which anti-amyloid inhibitors are prone. The ultimate goal of all the proposed studies is to define the molecular events that feature in the formation of human prions in order to develop therapeutics that cure the human prion diseases. RELEVANCE: Prions are infectious proteins that cause age-dependent neurodegeneration in humans and animals. The accumulation of an alternatively folded isoform of the prion protein (PrPSc) in the brains of humans and animals is the hallmark of the prion disorders that include Creutzfeldt-Jakob disease (CJD). The prion diseases are invariably fatal and no effective treatment exists. The successful development of a drug for CJD will have important implications for creating meaningful treatments for other age-dependent neurodegenerative disorders that include Alzheimer's disease.