Intracellular labile iron pools as direct targets of iron chelators: a fluorescence study of chelator action in living cells
Intracellular labile iron pools as direct targets of iron chelators: a fluorescence study of chelator action in living cells
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DOI：
10.1182/blood-2005-02-0460
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发表时间：
2005-11-01
期刊：
影响因子：
20.3
通讯作者：
Cabantchik, ZI
中科院分区：
文献类型：
--
作者：
Glickstein, H;Ben El, R;Cabantchik, ZI
铁络合剂用于治疗输血铁超载的主要靶点是防止铁进入组织及其清除细胞内的铁。本研究旨在阐明临床上重要的铁络合剂如去铁酮(DFP)、去铁胺和ICL670的能力：(A)直接进入铁聚集的关键细胞(巨噬细胞、肝细胞和心肌细胞系)的细胞内铁库；(B)螯合存在于离散细胞隔室/细胞器中的活性铁；以及(C)防止活性铁参与活性氧化剂的产生。通过荧光金属传感器(作为钙蛋白的铁猝灭络合物)的荧光显微成像，动态和定量地显示活细胞中胞液和细胞器中铁的螯合作用。荧光恢复的速度和程度提供了对特定细胞部位/细胞器可及性的原位测量。与细胞隔间相关的互补荧光氧化还原探针能够识别对螯合剂敏感的局部反应性氧化剂的产生。我们的研究表明，去铁胺的螯合作用是缓慢的，在内吞活性相对较高的细胞中得到加强，而ICL670和DFP很容易进入大多数细胞，并有效地到达铁积累的主要细胞内部位。
The primary targets of iron chelators used for treating transfusional iron overload are prevention of iron ingress into tissues and its intracellular scavenging. The present study was aimed at elucidating the capacity of clinically important iron chelators such as deferiprone (DFP), desferrioxamine, and ICL670 to (a) gain direct access to intracellular iron pools of key cells of iron accumulation (macrophages, hepatocytes, and cardiomyocyte cell lines); (b) chelate the labile iron present in discrete cell compartments/organelles; and (c) prevent labile iron involvement in the generation of reactive oxidant species. Chelation of cytosolic and organellar cell iron was visualized dynamically and quantitatively in living cells by fluorescence microscopic imaging of fluorescent metallosensors (used as iron-quenched complexes of calceins) targeted to either cytosol, endosome-lysosomes, or mitochondria. The rate and extent of fluorescence recovery provided an in situ measure of the accessibility of chelators to particular cell sites/organelles. Complementary, fluorogenic redox probes associated with cell compartments enabled identification of chelator-sensitive, localized reactive oxidant production. Our studies indicate that chelation by desferrioxamine is slow and is enhanced in cells with relatively high endocytic activities, while ICL670 and DFP readily enter most cells and efficiently reach the major intracellular sites of iron accumulation.