Martin Pamela M, Gnana-Prakasam Jaya P, Roon Penny, Smith Robert G, Smith Sylvia B, Ganapathy Vadivel
Department of Biochemistry, Medical College of Georgia, Augusta, GA 30912, USA.
Invest Ophthalmol Vis Sci. 2006 Oct;47(10):4238-44. doi: 10.1167/iovs.06-0026.
Hereditary hemochromatosis is an autosomal recessive disorder of iron overload leading to oxidative stress. Mutations in HFE are responsible for approximately 90% of cases of this disease. HFE is the principal regulator of iron homeostasis, and the process involves interaction with transferrin receptor (TfR)-1, transferrin receptor (TfR)-2, and beta2-microglobulin (beta2M). Expression of HFE has not been investigated in the retina. In the present study, the expression of HFE and the HFE-interacting proteins TfR1, TfR2, and beta2M were analyzed in mouse retina.
RT-PCR was used to detect the expression of HFE mRNA in neural retina and the RPE-eyecup. Expression of HFE in intact retina was investigated by in situ hybridization, immunofluorescence, and immunogold electron microscopy. Expression of HFE-interacting proteins was also analyzed using similar techniques.
RT-PCR showed predominant expression of HFE mRNA in the RPE-eyecup. In situ hybridization in intact retina revealed that HFE mRNA is expressed almost exclusively in RPE Immunofluorescence and immunogold electron microscopy showed that HFE protein was specifically associated with the basolateral membrane of RPE. Expression of the HFE-interacting proteins TfR1, TfR2, and beta2M was also evident in the retina.
This is the first report on the expression of HFE in the retina. The specific localization of HFE and its interacting proteins, TfR1 and TfR2, at the basolateral membrane of RPE is relevant to the regulation of iron homeostasis in this cell. Patients with hemochromatosis may have impairment of iron homeostasis in RPE, potentially contributing to age-related RPE dysfunction and retinal degeneration.
遗传性血色素沉着症是一种常染色体隐性铁过载疾病,可导致氧化应激。HFE基因的突变导致了约90%的该疾病病例。HFE是铁稳态的主要调节因子,该过程涉及与转铁蛋白受体(TfR)-1、转铁蛋白受体(TfR)-2和β2-微球蛋白(β2M)的相互作用。尚未对视网膜中HFE的表达进行研究。在本研究中,分析了小鼠视网膜中HFE及其相互作用蛋白TfR1、TfR2和β2M的表达。
采用逆转录聚合酶链反应(RT-PCR)检测神经视网膜和视网膜色素上皮(RPE)-眼杯组织中HFE mRNA的表达。通过原位杂交、免疫荧光和免疫金电子显微镜研究完整视网膜中HFE的表达。还使用类似技术分析了HFE相互作用蛋白的表达。
RT-PCR显示HFE mRNA在RPE-眼杯组织中表达占主导。完整视网膜的原位杂交显示,HFE mRNA几乎仅在RPE中表达。免疫荧光和免疫金电子显微镜显示,HFE蛋白与RPE的基底外侧膜特异性相关。HFE相互作用蛋白TfR1、TfR2和β2M在视网膜中的表达也很明显。
这是关于视网膜中HFE表达的首次报道。HFE及其相互作用蛋白TfR1和TfR2在RPE基底外侧膜的特异性定位与该细胞中铁稳态的调节有关。血色素沉着症患者的RPE中铁稳态可能受损,这可能导致与年龄相关的RPE功能障碍和视网膜变性。