Ferroxidases in RPE iron transport

描述（由申请人提供）：铁在视网膜中是氧化磷酸化、膜生物发生和许多其他代谢过程所必需的，但如果调节不当，也会产生氧化应激，导致细胞死亡。铁在视网膜变性中起着重要作用，如下：1）铁毒性在由眼内异物携带的铁直接进入眼睛后引起视网膜变性2）铁已经涉及RCS大鼠的视网膜变性，其中铁过载的机制是间接的。3)人类AMD视网膜比年龄匹配的对照组具有更多的铁，这表明铁过载可能在AMD发病机制中起作用。4)铁代谢的遗传缺陷导致弗里德赖希共济失调、泛酸激酶相关神经病和浆细胞蛋白血症中的视网膜变性。目前的建议的重点是了解铁氧化酶铜蓝蛋白（Cp）和它的同系物肝铁蛋白（Heph）在眼铁稳态的功能。在目标1中，将评估Cp和Heph的视网膜定位。在目标2中，将产生RPE特异性Heph敲除。这将确定RPE Heph表达是否是RPE铁稳态所必需的。它还应该提供视网膜变性的小鼠模型，其像我们的Cp-/-Heph-/-小鼠一样具有视网膜下新血管形成，但与Cp-/-Heph-/-小鼠不同，具有正常的寿命。此外，它还将为眼科研究界提供产生RPE特异性敲除的试剂。在目的3中，将表征Cp-/-Heph-/-和Cp-/-RPE特异性Heph-/-小鼠中的视网膜变性。氧化应激和新血管形成的机制将被研究。在目的4中，RPE体外系统将用于确定Cp和Heph是否介导RPE铁输入或输出，并评估转运的极性。这些研究是重要的，因为：1）浆细胞蛋白血症中视网膜变性的机制尚不清楚。2)Cp和Heph的视网膜功能尚不清楚。3)我们的初步研究表明，Cp-/-Heph-/-小鼠将提供AMD的几个特征，包括视网膜下新生血管的模型。4)这些小鼠将提供由铁水平的年龄依赖性增加引起的神经变性的模型，最近的报告表明这可能有助于阿尔茨海默病和帕金森病以及AMD的发病机制。5)这些小鼠将提供测试铁螯合剂和抗氧化剂作为这些年龄相关疾病的潜在治疗/预防的机会。

DESCRIPTION (provided by applicant): Iron is necessary in the retina for oxidative phosphorylation, membrane biogenesis and many other metabolic processes, but can also produce oxidative stress if improperly regulated, leading to cell death. Iron plays a significant role in retinal degeneration, as follows: 1) Iron toxicity causes retinal degeneration following direct entry of iron into the eye carried by an intraocular foreign body 2) Iron has been implicated in the RCS rats' retinal degeneration, in which the mechanism of iron overload is indirect. 3) Human AMD retinas have more iron than age-matched controls, suggesting that iron overload may play a role in AMD pathogenesis. 4) Inherited defects in iron metabolism result in retinal degeneration in Friedreich's ataxia, pantothenate kinase associated neuropathy, and aceruloplasminemia. The focus of the current proposal is to understand the functions in ocular iron homeostasis of the ferroxidases ceruloplasmin (Cp) and its homologue hephaestin (Heph). In Aim 1, the retinal localization of Cp and Heph will be assessed. In Aim 2, an RPE-specific Heph knockout will be generated. This will determine whether RPE Heph expression is necessary for RPE iron homeostasis. It should also provide a mouse model of retinal degeneration that like our Cp-/-Heph-/- mice, has subretinal neovascularization, but unlike Cp-/-Heph-/- mice, has a normal lifespan. In addition it will provide reagents for generating RPE-specific knockouts for the eye research community. In Aim 3, the retinal degeneration in Cp-/-Heph-/- and Cp-/-RPE-specific Heph-/- mice will be characterized. Both oxidative stress and mechanisms of neovascularization will be studied. In Aim 4 an RPE in vitro system will be used to determine whether Cp and Heph mediate RPE iron import or export, and assess the polarity of transport. These studies are important because: 1) The mechanism of retinal degeneration in aceruloplasminemia is not known. 2) The retinal functions of Cp and Heph are not known. 3) Our preliminary studies show that Cp-/-Heph-/- mice will provide a model for several features of AMD, including subretinal neovascularization. 4) These mice will provide a model of neurodegeneration caused by age-dependent increases in iron levels, which recent reports suggest may contribute to the pathogenesis of Alzheimer's and Parkinson's diseases and AMD. 5) These mice will provide the opportunity to test iron chelators and antioxidants as potential treatments/preventions for those age-related diseases.