The iron modulatory function of prion protein and prion disorders

朊病毒蛋白和朊病毒疾病的铁调节功能

• 批准号: 7906472
• 负责人: Neena Singh
• 金额: $ 39.25万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-15 至 2014-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7906472
• 关键词: Acute Erythroblastic Leukemia; Affect; Animals; Biochemical Pathway; Biology; Blood; Brain; Caco-2 Cells; Carrier Proteins; Cell Surface Proteins; Cells; Data; Deposition; Disease; Disease Progression; Duodenum; Endothelial Cells; Enterocytes; Glycoproteins; Goals; Hamsters; Hematopoietic; Homeostasis; Human; Investigation; Iron; K-562; Knock-out; Knockout Mice; Laboratories; Modeling; Molecular Conformation; Molecular Weight; Mus; Nerve Degeneration; Neuraxis; Neuroblastoma; Neurons; Normal Cell; Organ; Pathogenesis; Pathway interactions; Phenotype; Plasma; Play; PrP; PrPC function; PrPSc Proteins; Prion Diseases; Prions; Process; Proteins; Relative (related person); Reporting; Role; Scrapie; Source; Stream; Suggestion; Testing; Tissues; Transferrin; base; cell type; haemoferritin; improved; in vitro Model; in vivo; intestinal epithelium; iron metabolism; loss of function; mouse model; mutant; neurotoxicity; novel; precursor cell; programs; public health relevance; uptake; wild-type PrP

DESCRIPTION (provided by applicant): Prion protein (PrPC) is a normal glycoprotein implicated in the pathogenesis of prion disorders, a group of fatal neurodegenerative conditions of humans and animals. A change in the conformation of PrPC to an aggregated, PrP-scrapie (PrPSc) form is believed to be the principal cause of neurotoxicity in these disorders. Recently, we demonstrated that PrPC plays a functional role in cellular iron uptake and transport, and selective deletion of PrPC in PrP knock-out (PrPKO) mice induces a state of systemic iron deficiency in these animals relative to wild-type (wt) controls. Specifically, PrPKO mice show impaired transport of orally introduced iron from the duodenum to the blood stream, and inefficient uptake of plasma iron by hematopoietic precursor cells and parenchymal cells of major organs. Together with our recent report demonstrating a phenotype of iron deficiency that correlates with PrPSc deposits in prion disease affected brains, these observations suggest that loss of normal function of PrPC due to aggregation to the PrPSc form may be responsible for brain iron dys- homeostasis in diseased brains. In this application, we will focus on the mechanism of iron modulation by PrPC, and hypothesize that PrPC is a novel iron uptake and transport protein, and modulates cellular iron metabolism either directly or by interacting with other iron transport protein(s). The proposed studies will test this hypothesis using two complementary approaches: 1) by evaluating the transport of different sources of iron that utilize distinct pathways of transport in the same tissue, and 2) by investigating the transport of same source of iron across tissues that utilize distinct pathways of uptake and transport. Mouse models that express no PrPC (PrPKO), wt levels (wt), and 10-fold higher than wt levels of PrPC (PrPOV) will be used for this analysis. This approach will allow identification of pathways of iron transport by PrPC, and the point where PrPC intersects with known pathways of iron metabolism. Three specific aims are proposed to accomplish these goals. In aim 1, the functional role of PrPC in brain iron metabolism will be evaluated in wt, PrPKO, and PrPOV mice, and the underlying mechanism will be investigated in neuroblastoma cells expressing normal and mutant forms of PrP defective in iron transport. In addition, the correlation between PrPC, PrPSc, and brain iron status will be assessed in scrapie infected wt and PrPOV mice. In aim 2, the transport of different sources of iron will be checked in hematopoietic and reticuloendothelial cells isolated from wt, PrPKO, and PrPOV mice, and the underlying mechanism will be investigated in K562 erythroleukemia cells transfected with normal and mutant PrP forms. In aim 3, the uptake and transport of different sources of iron across the intestinal epithelium will be checked in wt, PrPKO, and PrPOV mice, and compared with aim 2 above. Based on in vivo results, polarized Caco-2 cells transfected to express PrPC or mutant PrP forms will be used as models of absorptive enterocytes to understand the mechanism of iron transport by PrPC. Successful completion of these studies will uncover novel pathway(s) of iron modulation by PrPC, and improve our understanding of the mechanism(s) underlying brain iron imbalance and associated neurotoxicity in prion disorders. PUBLIC HEALTH RELEVANCE: The long term goal of this application is to understand the role of prion protein (PrPC) in iron uptake, transport, and utilization. Preliminary data from my laboratory demonstrate that PrPC is involved in iron uptake and transport, and loss of this function contributes to brain iron dyshomeostasis in prion disorders. Successful completion of the proposed studies will improve our understanding of the functional role of PrPC in iron metabolism, and the underlying cause of brain iron imbalance in prion disorders.

描述(申请人提供)：普鲁恩蛋白(PrPC)是一种正常的糖蛋白，与普鲁恩疾病的发病机制有关，普鲁恩疾病是一组致命的人类和动物神经变性疾病。PrPC的构象变化为聚集的PrP-scrapie(PrPSc)形式被认为是这些疾病中神经毒性的主要原因。最近，我们发现PrPC在细胞铁的摄取和运输中起着重要的作用，PrP基因敲除小鼠(PrPKO)中PrPC的选择性缺失导致这些动物相对于野生型(Wt)对照动物处于全身性缺铁状态。具体地说，PrPKO小鼠表现出口服引入的铁从十二指肠到血流的运输受损，主要器官的造血祖细胞和实质细胞对血浆铁的吸收效率低下。结合我们最近的报告，我们发现了一种与PrPSc沉积相关的缺铁表型，这些观察表明，PrPC由于聚集到PrPSc形式而失去正常功能，可能是疾病大脑中铁的动态平衡失调的原因。在这一应用中，我们将重点研究PrPC对铁的调节机制，并假设PrPC是一种新的铁摄取和运输蛋白，可以直接或通过与其他铁运输蛋白(S)相互作用来调节细胞内的铁代谢。拟议的研究将使用两种互补的方法来验证这一假说：1)通过评估不同来源的铁在同一组织中利用不同的运输途径进行运输，以及2)通过调查相同来源的铁在利用不同吸收和运输途径的组织之间的运输。不表达PrPC(PrPKO)、wt水平(Wt)以及比wt水平高10倍的PrPC(PrPOV)的小鼠模型将用于此分析。这种方法将允许确定PrPC运输铁的途径，以及PrPC与已知的铁代谢途径的交叉点。为实现这些目标，提出了三个具体目标。在目标1中，将评估PrPC在WT、PrPKO和PrPOV小鼠脑铁代谢中的功能作用，并将在表达铁转运缺陷的PrP正常和突变形式的神经母细胞瘤细胞中探讨其潜在机制。此外，还将在感染瘙痒病的wt和PrPOV小鼠中评估PrPC、PrPSc和脑铁状态之间的相关性。在目标2中，将检测从wt、PrPKO和PrPOV小鼠分离的造血细胞和网状内皮细胞中不同来源的铁的转运，并将在转导正常和突变PrP形式的K562红白血病细胞中探讨其潜在的机制。在目标3中，将检查wt、PrPKO和PrPOV小鼠对不同来源的铁的吸收和跨肠上皮的运输，并与上面的目标2进行比较。根据体内实验结果，将表达PrPC或突变PrP形式的极化Caco-2细胞作为吸收肠细胞的模型，以了解PrPC转运铁的机制。这些研究的成功完成将揭示PrPC调控铁的新途径(S)，并提高我们对PrPC导致脑内铁失衡及其相关神经毒性机制(S)的理解。 公共卫生相关性：这项应用的长期目标是了解PrPC在铁的吸收、运输和利用中的作用。我实验室的初步数据显示，PrPC参与了铁的摄取和运输，这一功能的丧失导致了普恩疾病的脑铁代谢紊乱。这些研究的成功完成将提高我们对PrPC在铁代谢中的功能作用的理解，以及PrPC在蛋白质紊乱中大脑铁失衡的潜在原因的理解。