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: 8287667
• 负责人: Neena Singh
• 金额: $ 32.25万
• 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/8287667
• 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 deficiency; iron metabolism; loss of function; mouse model; mutant; neuroblastoma cell; 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（由申请人提供）：朊病毒蛋白（PrPC）是一种正常糖蛋白，与朊病毒疾病的发病机制有关，朊病毒疾病是人类和动物的一组致命的神经退行性疾病。 PrPC 构象向聚集的 PrP-scrapie (PrPSc) 形式的变化被认为是这些疾病中神经毒性的主要原因。最近，我们证明 PrPC 在细胞铁吸收和运输中发挥功能性作用，与野生型 (wt) 对照相比，PrP 敲除 (PrPKO) 小鼠中选择性删除 PrPC 会诱导这些动物出现全身缺铁状态。具体而言，PrPKO 小鼠表现出口服铁从十二指肠到血流的运输受损，并且造血前体细胞和主要器官的实质细胞对血浆铁的吸收效率低下。结合我们最近的报告，证明铁缺乏的表型与朊病毒病影响的大脑中的 PrPSc 沉积相关，这些观察结果表明，由于聚集成 PrPSc 形式而导致 PrPC 正常功能的丧失可能是患病大脑中脑铁稳态失调的原因。在本申请中，我们将重点研究 PrPC 调节铁的机制，并假设 PrPC 是一种新型的铁摄取和转运蛋白，并直接或通过与其他铁转运蛋白相互作用来调节细胞铁代谢。拟议的研究将使用两种互补的方法来检验这一假设：1）通过评估同一组织中利用不同运输途径的不同铁源的运输，2）通过研究利用不同吸收和运输途径的相同铁源跨组织的运输。不表达 PrPC (PrPKO)、wt 水平 (wt) 和 PrPC (PrPOV) 水平高于 wt 水平 10 倍的小鼠模型将用于此分析。这种方法将能够识别 PrPC 的铁转运途径，以及 PrPC 与已知铁代谢途径的交叉点。为了实现这些目标，提出了三个具体目标。在目标 1 中，将在 wt、PrPKO 和 PrPOV 小鼠中评估 PrPC 在脑铁代谢中的功能作用，并将在表达铁转运缺陷的正常和突变形式 PrP 的神经母细胞瘤细胞中研究其潜在机制。此外，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，将在从 wt、PrPKO 和 PrPOV 小鼠分离的造血细胞和网状内皮细胞中检查不同来源铁的转运，并将在用正常和突变型 PrP 形式转染的 K562 红白血病细胞中研究其潜在机制。在目标 3 中，将在 wt、PrPKO 和 PrPOV 小鼠中检查不同来源的铁穿过肠上皮的吸收和运输，并与上述目标 2 进行比较。根据体内结果，转染表达 PrPC 或突变型 PrP 形式的极化 Caco-2 细胞将用作吸收性肠上皮细胞模型，以了解 PrPC 铁转运的机制。这些研究的成功完成将揭示 PrPC 调节铁的新途径，并提高我们对朊病毒疾病中脑铁失衡和相关神经毒性的潜在机制的理解。 公共健康相关性：该应用的长期目标是了解朊病毒蛋白 (PrPC) 在铁吸收、运输和利用中的作用。我实验室的初步数据表明，PrPC 参与铁的摄取和运输，这种功能的丧失会导致朊病毒病中脑铁的稳态失调。成功完成拟议的研究将提高我们对 PrPC 在铁代谢中的功能作用以及朊病毒疾病中脑铁失衡的根本原因的理解。