Divergent consequences arise from metallothionein overexpression in astrocytes: Zinc buffering and oxidant-induced zinc release
Divergent consequences arise from metallothionein overexpression in astrocytes: Zinc buffering and oxidant-induced zinc release
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DOI：
10.1002/glia.10332
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发表时间：
2004-03-15
期刊：
影响因子：
6.2
通讯作者：
Reynolds, IJ
中科院分区：
文献类型：
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作者：
Malaiyandi, LM;Dineley, KE;Reynolds, IJ
重金属锌的过度蓄积具有细胞毒性。因此，细胞对锌诱导的损伤的易感性可能受到维持细胞内游离锌浓度的蛋白质的丰富([锌](I))的调节。在这项研究中，我们在星形胶质细胞中过表达锌结合蛋白金属硫蛋白-II(MT)，以评估其作为(1)急性锌缓冲机制和(2)氧化剂可释放锌池的影响。MT在原代星形胶质细胞培养中的过表达是使用腺病毒载体完成的。使用锌敏感的荧光指示剂MagFura-2，我们监测了刺激锌内流或氧化剂处理后的[锌](I)。在MT过度表达的情况下，我们观察到了一种急性缓冲效应，表现为抑制刺激诱导的[Zn2+](I)增加。相反，我们也看到应用2，2‘-二硫代联吡啶的巯基氧化剂促进了锌的释放。这些结果表明，锌结合蛋白的过表达可以在锌内流后迅速降低[Zn2+](I)，但在氧化应激条件下升高[Zn2+](I)，提供保护但潜在危险的效果。(C)2003年Wiley-Liss，Inc.
Excessive accumulation of the heavy metal zinc is cytotoxic. As a consequence, cellular vulnerability to zinc-induced injury may be regulated by the abundance of proteins that maintain intracellular free zinc concentrations ([Zn2+](i)). In this study, we overexpressed the zinc-binding protein metallothionein-II (MT) in astrocytes to assess its impact as (1) an acute zinc buffering mechanism, and (2) an oxidant-releasable zinc pool. Overexpression of MT in primary astrocyte cultures was accomplished using an adenoviral vector. Using the zinc-sensitive fluorescent indicator magfura-2, we monitored [Zn2+](i) after stimulating zinc influx or oxidant treatment. With MT overexpression, we observed an acute buffering effect manifested as a dampening of stimulus-induced increases in [Zn2+](i). In contrast, we also saw enhanced zinc release with application of the sulfhydryl oxidizing agent 2,2'-dithiodipyridine. These results indicate that overexpression of a zinc-binding protein can quickly diminish [Zn2+](i) following zinc influx, but elevate [Zn2+](i) under conditions of oxidative stress, providing protective yet potentially endangering effects. (C) 2003 Wiley-Liss, Inc.