Ferroxidases in RPE Iron Transport

RPE 铁转运中的铁氧化酶

基本信息

批准号：
7650575
负责人：
JOSHUA L DUNAIEF
金额：
$ 39.38万
依托单位：
UNIVERSITY OF PENNSYLVANIA
依托单位国家：
美国
项目类别：
财政年份：
2004
资助国家：
美国
起止时间：
2004-08-01 至 2013-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7650575
关键词：
Age Age related macular degeneration All-Trans-Retinol Anemia Binding Brain Breeding Cell Death Cell membrane Cells Ceruloplasmin Cessation of life Complement Activation Data Defect Embryo Eye Fertility Foreign Bodies Funding Goals Health Homeostasis Homologous Gene Hormones Human Inherited Iron Iron Overload Knock-out Knockout Mice Lead Learning Link Lipofuscin Liver Longevity Macular degeneration Mediating Modeling Muller&apos s cell Mus Mutant Strains Mice Mutation Nerve Degeneration Organ Oxidative Phosphorylation Oxidative Stress Pathogenesis Phagocytosis Photoreceptors Play Process Proteins Regulation Retina Retinal Retinal Degeneration Retinal Diseases Rhodopsin Role Route Serum iron level result Signal Transduction Technology Testing Therapeutic Tissues Toxic effect Transferrin Receptor Transgenic Mice Transgenic Organisms Work age related base cell type early onset extracellular ganglion cell hepcidin membrane biogenesis metal transporting protein 1 mouse model mutant neovascularization null mutation photoreceptor degeneration prevent protein function public health relevance sex

项目摘要

DESCRIPTION (provided by applicant): Iron is necessary in the retina for oxidative phosphorylation, membrane biogenesis and retinol isomerization, but can also produce oxidative stress if improperly regulated, leading to cell death. This can contribute to retinal disease as follows: 1) Iron toxicity causes rapid retinal degeneration following direct entry of iron into the eye carried by an intraocular foreign body. 2) Human AMD retinas have more iron than age-matched controls, suggesting that iron overload may play a role in AMD pathogenesis. 3) Inherited defects in the ferroxidase ceruloplasmin (Cp) result in retinal iron accumulation and early onset macular degeneration. 4) Mice with mutation in Cp and its homolog hephaestin (Heph) have an age-dependent retinal iron overload and degeneration with a number of features similar to AMD, including subretinal neovascularization. The latter two points indicate that Cp and Heph are important for retinal health. Evidence from other organs suggests that Cp or Heph can cooperate with the plasma membrane iron transporter ferroportin (Fpn) to export iron from cells. The goal of this proposal is to increase understanding of the roles of Cp, Heph and Fpn in retinal iron homeostasis and their regulation by the secreted hormone hepcidin (Hepc). Hepc is produced in the retina (as well as the liver) and triggers internalization and degradation of Fpn. Hepc may serve as a message from retinal cells sensing iron excess (such as photoreceptors) to degrade Fpn and limit iron transfer from RPE and Muller cells. Our existing Cp/Heph double mutant and Hepc-/- mice indicate that these three proteins are critical for retinal iron homeostasis and health, but provide little information about the specific functions of the proteins within the retina. Conditional mouse knockout technology (lox/cre) affords the opportunity to determine how these proteins function within specific retinal cell types and how intercellular iron transfer is executed and regulated. In Aim1, the photoreceptor-specific functions of Heph, a possible "iron release valve" to prevent PR iron overload will be investigated using a Heph conditional knockout on a Cp-/- background. In Aim 2, the iron transport function of Fpn will be investigated using RPE and photoreceptor-specific conditional knockout mice. In Aim 3, the retinal function of Hepc will be investigated in knockout and conditional knockout mice. These studies are important because: 1) They will provide new information about the cell-type specific functions of Heph, Fpn and Hepc and the routes of intercellular iron transfer that control retinal iron homeostasis. 2) The conditional knockout mice are likely to provide models for several features of AMD, including subretinal neovascularization while avoiding the lifespan-limiting brain iron overload in our existing Cp/Heph double mutant mice. PUBLIC HEALTH RELEVANCE: The proposed work on the mechanisms of retinal iron transport is relevant to retinal health since iron overload has been implicated in age-related macular degeneration (AMD) and other retinal diseases. The mouse models resulting from mutation of iron transporters are expected, based on our previous work, to have features of AMD, including subretinal neovascularization, photoreceptor and RPE death, lipofuscin accumulation, and activation of the complement cascade. These models will provide a platform for understanding the mechanisms of retinal iron regulation and testing potential therapeutics for retinal disease.

描述（由申请人提供）：在视网膜中需要铁以用于氧化磷酸化，膜生物发生和视黄醇异构化，但如果受到不当调节，也会产生氧化应激，从而导致细胞死亡。这可能会导致视网膜疾病如下：1）铁毒性导致铁直接进入人眼内异物携带的眼睛后的快速视网膜变性。 2）人类AMD视网膜的铁比年龄匹配的对照更多，这表明铁超负荷可能在AMD发病机理中起作用。 3）铁氧化酶Ceruloplasmin（CP）中的遗传缺陷导致视网膜铁的积累和早期发作黄斑变性。 4）CP中具有突变及其同源性hephaestin（HEPH）的小鼠具有年龄依赖性的视网膜铁超载和变性，其多种特征与AMD相似，包括视网膜下新血管生成。后两个点表明CP和HEPH对视网膜健康很重要。来自其他器官的证据表明，CP或HEPH可以与质膜铁转运蛋白（FPN）合作以从细胞中输出铁。该提议的目的是增加对CP，HEPH和FPN在视网膜铁稳态中的作用的理解，以及对分泌的激素肝素（HEPC）的调节。 HEPC在视网膜（以及肝脏）中产生，并触发FPN的内在化和降解。 HEPC可以用作视网膜细胞中传感过量铁（例如感光体）的消息，以降解FPN并限制铁从RPE和Muller细胞中转移。我们现有的CP/HEP双突变体和HEPC - / - 小鼠表明，这三种蛋白质对于视网膜铁稳态和健康至关重要，但很少提供有关视网膜内蛋白质特定功能的信息。有条件的小鼠敲除技术（LOX/CRE）为确定这些蛋白质在特定的视网膜细胞类型中的作用以及细胞间铁转移的执行和调节方式提供了机会。在AIM1中，HEPH的光感受器特异性功能，将使用CP - / - 背景上的HEPH有条件敲除研究，以防止PR铁超载。在AIM 2中，将使用RPE和光感受器特异性敲除小鼠研究FPN的铁运输功能。在AIM 3中，HEPC的视网膜功能将在敲除和有条件的敲除小鼠中进行研究。这些研究很重要，因为：1）他们将提供有关HEP，FPN和HEPC的细胞类型特异性功能以及控制视网膜铁稳态的细胞间铁转移途径的新信息。 2）条件敲除小鼠可能会为AMD的多种特征提供模型，包括视网膜下新血管形成，同时避免了我们现有的CP/HEPH双突变小鼠中限制寿命的脑铁超载。公共卫生相关性：关于视网膜铁运输机制的拟议工作与视网膜健康有关，因为铁超负荷与年龄相关的黄斑变性（AMD）和其他视网膜疾病有关。根据我们先前的工作，预期由铁转运蛋白突变产生的小鼠模型具有AMD的特征，包括视网膜下新生血管，感光器和RPE死亡，脂肪霉素的积累以及补体级联反应的激活。这些模型将为理解视网膜铁调节的机制提供一个平台，并测试视网膜疾病的潜在疗法。