Role of ferritin in the control of the labile iron pool in murine erythroleukemia cells
Role of ferritin in the control of the labile iron pool in murine erythroleukemia cells
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DOI：
10.1074/jbc.273.25.15382
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发表时间：
1998-06-19
影响因子：
4.8
通讯作者：
Beaumont, C
中科院分区：
文献类型：
--
作者：
Picard, V;Epsztejn, S;Beaumont, C
体外研究表明，铁蛋白铁掺入是由与铁蛋白H亚基（H-Ft）相关的铁氧化酶活性和与铁蛋白L亚基（L-Ft）相关的成核中心介导的。为了评估铁蛋白亚基在调节细胞内铁分布中所起的作用，我们用铁响应元件中突变的H-Ft亚基基因转染小鼠红白血病细胞。稳定的转染子显示高的H-Ft水平和降低的内源性L-Ft水平，导致H：L亚基比从对照细胞的1：1显著变化到一些转染克隆中高达20：1。通过一种基于荧光金属传感器钙黄绿素的新方法，在完整细胞中测定H-Ft过表达对不稳定铁池的影响。H-Ft过表达导致铁池显著减少，从对照细胞的1.3 μ m减少到H-Ft转染子的0.56 μ m，并且在铁负荷后具有更高的缓冲能力。一小部分的H-Ft相关的铁是不稳定的，可用于细胞渗透，但不是细胞不渗透，螯合剂。这项研究的结果提供了第一次在体内直接证明的能力H-Ft螯合细胞铁和调节水平的不稳定铁池。
In vitro studies have shown that ferritin iron incorporation is mediated by a ferroxidase activity associated with ferritin H subunits (H-Ft) and a nucleation center-associated with ferritin L subunits (L-Ft). To assess the role played by the ferritin subunits in regulating intracellular iron distribution, we transfected mouse erythroleukemia cells with the H-Ft subunit gene mutated in the iron-responsive element, Stable transfectants displayed high H-Ft levels and reduced endogenous L-Ft levels, resulting in a marked change in the H:L subunit ratio from 1:1 in control cells to as high as 20:1 in some transfected clones. The effects of H-Ft overexpression on the labile iron pool were determined in intact cells by a novel method based on the fluorescent metallosensor calcein, H-Ft overexpression resulted in a significant reduction in the iron pool, from 1.3 mu m in control cells to 0.56 mu m in H-Ft transfectants, and in higher buffering capacity following iron loads. A fraction of the H-Ft-associated iron was labile, available to cell-permeant, but not cell-impermeant, chelators. The results of this study provide the first in vivo direct demonstration of the capacity of H-Ft to sequester cell iron and to regulate the levels of the labile iron pool.