Mechanisms of HFE-induced regulation of iron homeostasis: Insights from the W81A HFE mutation.
Mechanisms of HFE-induced regulation of iron homeostasis: Insights from the W81A HFE mutation.
复制标题
HFE 诱导的铁稳态调节机制：W81A HFE 突变的见解。
DOI：
10.1073/pnas.1233675100
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发表时间：
2003
影响因子：
11.1
通讯作者：
Enns,CarolineA
中科院分区：
文献类型：
--
作者：
Zhang,An-Sheng;Davies,PaigeS;Carlson,HanqianL;Enns,CarolineA
研究了遗传性血色素沉着症蛋白HFE降低转铁蛋白介导的铁摄取的机制。使用溶解细胞提取物的共免疫沉淀研究表明，转铁蛋白（Tf）与转铁蛋白受体（TfR）结合竞争，类似于之前使用可溶性截断形式的HFE和TfR的体外研究。当Tf浓度接近血液中发现的浓度时，检测到Tf与细胞的结合没有差异，这与HFE与TfR的结合常数比Tf低一致。然而，表达HFE的细胞在足以使HFE与TfR分离的Tf浓度下，仍表现出Tf介导的铁摄取减少。这些结果表明，HFE与TfR的关联并不是其降低细胞内铁储量的能力所必需的。为了测试HFE对降低细胞内铁水平的作用，而不依赖于其与TfR的关联，将对TfR亲和力大大降低的突变HFE （fW81AHFE）转染到四环素控制的反激活子HeLa细胞中。表达fW81AHFE的HeLa细胞表现出与表达野生型HFE的细胞相似的方式，通过铁调节蛋白凝胶转移测定细胞内铁水平和铁蛋白水平。结果表明，HFE可以独立于其与TfR的相互作用而降低细胞内铁水平。
The mechanisms by which the hereditary hemochromatosis protein, HFE, decreases transferrin-mediated iron uptake were examined. Coimmunoprecipitation studies using solubilized cell extracts demonstrated that transferrin (Tf) competed with HFE for binding to the transferrin receptor (TfR) similar to previousin vitrostudies using soluble truncated forms of HFE and the TfR. At concentrations of Tf approaching those found in the blood, no differences in Tf binding to cells were detected, which is consistent with the lower binding constant of HFE for TfR versus Tf. However, cells expressing HFE still showed a decrease in Tf-mediated iron uptake at concentrations of Tf sufficient to dissociate HFE from the TfR. These results indicate that the association of HFE with TfR is not essential for its ability to lower intracellular iron stores. To test the effect of HFE on lowering intracellular iron levels independently of its association with TfR, a mutated HFE (fW81AHFE) that shows greatly reduced affinity for the TfR was transfected into tetracycline-controlled transactivator HeLa cells. HeLa cells expressing fW81AHFE behaved in a similar manner to cells expressing wild-type HFE with respect to decreased intracellular iron levels measured by iron regulatory protein gel-shift assays and ferritin levels. The results indicate that HFE can lower intracellular iron levels independently of its interaction with the TfR.