Fe(II) Ion Release during Endocytotic Uptake of Iron Visualized by a Membrane-Anchoring Fe(II) Fluorescent Probe
Fe(II) Ion Release during Endocytotic Uptake of Iron Visualized by a Membrane-Anchoring Fe(II) Fluorescent Probe
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DOI：
10.1021/acschembio.7b00939
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发表时间：
2018-07-01
影响因子：
4
通讯作者：
Nagasawa, Hideko
中科院分区：
文献类型：
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作者：
Niwa, Masato;Hirayama, Tasuku;Nagasawa, Hideko
铁是所有生物体必需的过渡金属物质，并基于其氧化还原活性发挥各种重要的生理作用;因此，铁稳态的破坏引发氧化应激和细胞损伤。因此，细胞已经发展出复杂的铁摄取机制来获得铁，同时保护细胞在摄取过程中免受不受控制的氧化损伤。要检查的详细机制，同时控制的氧化还原状态的铁摄取，有必要开发有用的方法与氧化还原状态的选择性，灵敏度和细胞器的特异性，以监测不稳定的铁，这是弱结合的亚细胞配体。在这里，我们报告Mem-RhoNox的发展，以监测活细胞质膜表面的局部Fe（II）。探针的氧化还原状态选择性荧光响应依赖于我们最近开发的N-氧化物策略，该策略适用于在其r-共轭体系中具有二烷基芳基胺的荧光团。Mem-RhoNox由N-氧化的罗丹明支架组成，该支架具有两个臂，这两个臂都与棕榈酰基作为膜锚定结构域连接。在水性缓冲液中，Ac-RhoNox，Mem-RhoNox的模型化合物，显示出对Fe（II）氧化还原状态选择性的荧光开启响应。Mem-RhoNox及其衍生物的成像研究表明，不稳定的Fe（II）是瞬时产生的主要铁摄取途径：内吞摄取和直接运输。此外，Mem-RhoNox能够监测内吞摄取期间原代培养神经元中的内体Fe（II）。这份报告是第一个例子，确定生成的Fe（II）的过程中的细胞铁吸收过程。
Iron is an essential transition metal species for all living organisms and plays various physiologically important roles on the basis of its redox activity; accordingly, the disruption of iron homeostasis triggers oxidative stress and cellular damage. Therefore, cells have developed sophisticated iron-uptake machinery to acquire iron while protecting cells from uncontrolled oxidative damage during the uptake process. To examine the detailed mechanism of iron uptake while controlling the redox status, it is necessary to develop useful methods with redox state selectivity, sensitivity, and organelle specificity to monitor labile iron, which is weakly bound to subcellular ligands. Here, we report the development of Mem-RhoNox to monitor local Fe(II) at the surface of the plasma membrane of living cells. The redox state-selective fluorescence response of the probe relies on our recently developed N-oxide strategy, which is applicable to fluorophores with dialkylarylamine in their r-conjugation systems. Mem-RhoNox consists of the N-oxygenated rhodamine scaffold, which has two arms, both of which are tethered with palmitoyl groups as membrane-anchoring domains. In an aqueous buffer, Ac-RhoNox, a model compound of Mem-RhoNox, shows a fluorescence turn-on response to the Fe(II) redox state-selectively. An imaging study with Mem-RhoNox and its derivatives reveals that labile Fe(II) is transiently generated during the major iron-uptake pathways: endocytotic uptake and direct transport. Furthermore, Mem-RhoNox is capable of monitoring endosomal Fe(II) in primary cultured neurons during endocytotic uptake. This report is the first example that identifies the generation of Fe(II) over the course of cellular iron-uptake processes.