Immunolocalization and regulation of iron handling proteins ferritin and ferroportin in the retina.
Immunolocalization and regulation of iron handling proteins ferritin and ferroportin in the retina.
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发表时间：
2004-08
期刊：
影响因子：
2.2
通讯作者：
P. Hahn;T. Dentchev;Y. Qian;T. Rouault;Z. Harris;J. Dunaief
中科院分区：
文献类型：
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作者：
P. Hahn;T. Dentchev;Y. Qian;T. Rouault;Z. Harris;J. Dunaief
目的中枢神经系统铁蓄积与多种神经退行性疾病有关，包括老年性黄斑变性。细胞内游离铁的超载在一定程度上是通过铁输出蛋白铁蛋白和铁储存蛋白铁蛋白来防止的。本研究的目的是评估视网膜铁蛋白和铁蛋白的定位和调节。方法用免疫组织化学方法对正常小鼠视网膜进行铁蛋白、胞质铁蛋白和线粒体铁蛋白的定位，并用细胞特异性标志物进行双标记法鉴定细胞类型。缺乏铁氧合酶的视网膜，铜蓝蛋白和肝素，在它们的视网膜和RPE中积累铁，而缺乏铁调节蛋白(IRPS)的视网膜缺乏调节与铁代谢有关的几种蛋白质的能力；这些基因敲除小鼠的视网膜以及它们年龄匹配的野生型小鼠的视网膜也被检测，以研究铁蛋白和铁波特蛋白的调节。为了能够在视网膜色素上皮细胞中显示标记，着色鼠的切片在IHC之前用过氧化氢漂白，这是这项技术在RPE研究中的一种新用途。结果在正常视网膜中，胞浆铁蛋白主要分布于视杆双极细胞和感光细胞。在视网膜色素上皮细胞和Müler细胞中发现了铁孔蛋白。铜蓝蛋白和肝磷脂缺乏的小鼠体内铁的积累与铁蛋白和铁蛋白的上调有关。缺乏IRPS的小鼠表现出铁蛋白和铁蛋白的上调，可能是因为它们无法抑制翻译。结论正常视网膜中含有铁蛋白和铁蛋白，它们的水平受铁反应、铁调节蛋白的调节。铁门蛋白与铜蓝蛋白和肝素共定位于RPE和Müler细胞，支持这些铁氧合酶和铁输出子之间的潜在合作。胞浆铁蛋白聚集在杆状双极突触终末，提示铁蛋白可能参与轴突铁转运。线粒体铁蛋白随着铁的积累而增加，这表明它在铁的储存中发挥了作用。
PURPOSE CNS iron accumulation is associated with several neurodegenerative diseases, including age-related macular degeneration. Intracellular overload of free iron is prevented, in part, by the iron export protein, ferroportin, and the iron storage protein, ferritin. The purpose of this study was to assess retinal localization and regulation of ferroportin and ferritin. METHODS Normal murine retinas were analyzed by immunohistochemistry to localize ferroportin, cytosolic ferritin, and mitochondrial ferritin, with double-labeling using cell-specific markers to identify cell types. Retinas deficient in the ferroxidases, ceruloplasmin and hephaestin, accumulate iron in their retinas and RPE, while retinas deficient in iron regulatory proteins (IRPs) lack the ability to regulate several proteins involved in iron metabolism; retinas from these knockout mice along with their age matched wild type littermates were also examined to study regulation of ferritin and ferroportin. To enable visualization of label in the retinal pigment epithelial cells, sections from pigmented mice were bleached with H2O2 prior to IHC, a novel use of this technique for study of the RPE. RESULTS In normal retinas, cytosolic ferritins were found predominantly in rod bipolar cells and photoreceptors. Ferroportin was found in RPE and Müller cells. Iron accumulation in mice deficient in ceruloplasmin and hephaestin was associated with upregulation of ferritin and ferroportin. Mice deficient in IRPs showed upregulation of ferritin and ferroportin, likely because of their inability to repress translation. CONCLUSIONS Normal retinas contain ferritin and ferroportin, whose levels are regulated by iron-responsive, iron regulatory proteins. Ferroportin colocalizes with ceruloplasmin and hephaestin to RPE and Müller cells, supporting a potential cooperation between these ferroxidases and the iron exporter. Cytosolic ferritin accumulates in rod bipolar synaptic terminals, suggesting that ferritin may be involved in axonal iron transport. Mitochondrial ferritin increases with iron accumulation, suggesting a role in iron storage.