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（由申请人提供）：prion蛋白（PRPC）是一种正常的糖蛋白，与人类和动物的一组致命神经退行性疾病有关。据信，PRPC构象为汇总的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，我们证明了PRPC在细胞铁的摄取和运输中起功能性作用，并且在PRP敲除（PRPKO）小鼠中对PRPC的选择性缺失诱导这些动物的系统性铁缺乏状态，相对于野生型（WT）对照。具体而言，PRPKO小鼠表明，口服引入的铁从十二指肠到血流的运输受损，以及造血前体细胞和主要器官实质细胞对血浆铁的效率低下。连同我们最近的报告表明，铁缺乏症的表型与受prion疾病受影响的大脑中的PRPSC沉积物相关，这些观察结果表明，PRPC正常功能因PRPSC形式的正常功能的丧失可能导致患病大脑中的脑铁Dys-稳态。在此应用中，我们将重点关注PRPC铁调节的机理，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（S）相互作用来调节细胞铁的代谢。拟议的研究将使用两种互补方法检验这一假设：1）通过评估不同铁的运输，这些铁的运输利用了同一组织中使用不同的运输途径，以及2）通过研究使用相同的铁源跨组织的运输，这些组织利用了采用和运输的不同途径。该分析将使用不表达不表达PRPC（PRPKO），WT水平（WT）和10倍的PRPC（PRPC）（PRPOV）的小鼠模型进行此分析。这种方法将允许通过PRPC鉴定铁运输的途径，以及PRPC与已知的铁代谢途径相交的点。提出了三个具体目标来实现这些目标。在AIM 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PRP的正常和突变形式的神经细胞细胞中研究基本机制。另外，将在被抓感染的WT和PRPOV小鼠中评估PRPC，PRPSC和脑铁状态之间的相关性。在AIM 2中，将在从WT，PRPKO和PRPOV小鼠中分离出的造血和网状内皮细胞中检查不同的铁的运输，并将在K562红细胞蛋白酶细胞中以正常和突变的PRP形式进行K562红细胞蛋白磷脂细胞进行研究。在AIM 3中，将在WT，PRPKO和PRPOV小鼠中检查不同铁的摄取和运输在肠上皮上，并与上面的AIM 2相比。基于体内结果，转染以表达PRPC或突变体PRP形式的极化CACO-2细胞将用作吸收性肠细胞的模型，以了解PRPC铁转运的机理。这些研究的成功完成将揭示PRPC对铁调制的新途径，并提高我们对临床疾病中脑铁不平衡和相关神经毒性的理解。 公共卫生相关性：该应用的长期目标是了解prion蛋白（PRPC）在铁，运输和利用中的作用。我实验室的初步数据表明，PRPC参与了铁的吸收和运输，并且该功能的丧失导致脑铁dyshomeostasis在prion疾病中。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的理解，以及脑铁不平衡疾病中的根本原因。