Nickel Mobilizes Intracellular Zinc to Induce Metallothionein in Human Airway Epithelial Cells
Nickel Mobilizes Intracellular Zinc to Induce Metallothionein in Human Airway Epithelial Cells
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DOI：
10.1165/rcmb.2008-0409oc
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发表时间：
2009-07-01
影响因子：
6.4
通讯作者：
Barchowsky, Aaron
中科院分区：
文献类型：
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作者：
Nemec, Antonia A.;Leikauf, George D.;Barchowsky, Aaron
我们最近报道，诱导金属硫蛋白（MT）是关键限制镍（Ni）诱导的肺损伤在完整的小鼠。然而，镍诱导MT表达的机制尚不清楚。我们假设镍动员锌（Zn）的能力可能有助于这种调节，因此，我们研究了镍诱导的人气道上皮（BEAS-2B）细胞中MT 2A表达的机制。Ni诱导MT 2A转录水平和蛋白表达4小时。镍还增加了金属反应元件（MIRE）启动子荧光素酶报告基因构建体的活性，表明镍诱导金属转录因子（MTF-1）的MRE结合。暴露于镍导致MTF-1的核转位，镍不能诱导缺乏MTF-1的小鼠胚胎成纤维细胞中的MT。由于Zn是已知的直接结合MTF-1的唯一金属，我们随后表明Ni增加了细胞内Zn的不稳定池，如使用Zn敏感荧光团FluoZin-3的荧光激活细胞分选仪所揭示的。镍诱导的MT 2A mRNA和MRE-荧光素酶活性的增加对锌螯合剂TPEN敏感，支持锌在介导镍的作用中的重要作用。虽然不稳定的锌的来源和机制，镍释放不稳定的锌是显而易见的，它是值得注意的是，镍增加细胞内活性氧（ROS）。虽然N-乙酰半胱氨酸（NAC）和抗坏血酸（AA）降低镍诱导的ROS增加，只有NAC阻止镍诱导的MT 2A mRNA的增加，这表明镍，硫醇和锌释放的相互作用的特殊作用。
We recently reported that induction of metallothionein (MT) was critical in limiting nickel (Ni)-induced lung injury in intact mice. Nonetheless, the mechanism by which Ni induces MT expression is unclear. We hypothesized that the ability of Ni to mobilize zinc (Zn) may contribute to such regulation and therefore, we examined the mechanism for Ni-induced MT2A expression in human airway epithelial (BEAS-2B) cells. Ni induced MT2A transcript levels and protein expression by 4 hours. Ni also increased the activity of a metal response element (MIRE) promoter luciferase reporter construct, suggesting that Ni induces MRE binding of the metal transcription factor (MTF-1). Exposure to Ni resulted in the nuclear translocation of MTF-1, and Ni failed to induce MT in mouse embryonic fibroblasts lacking MTF-1. As Zn is the only metal known to directly bind MTF-1, we then showed that Ni increased a labile pool of intracellular Zn in cells as revealed by fluorescence-activated cell sorter using the Zn-sensitive fluorophore, FluoZin-3. Ni-induced increases in MT2A mRNA and MRE-luciferase activity were sensitive to the Zn chelator, TPEN, supporting an important role for Zn in mediating the effect of Ni. Although neither the source of labile Zn nor the mechanism by which Ni liberates labile Zn was apparent, it was noteworthy that Ni increased intracellular reactive oxygen species (ROS). Although both N-acetyl cysteine (NAC) and ascorbic acid (AA) decreased Ni-induced increases in ROS, only NAC prevented Ni-induced increases in MT2A mRNA, suggesting a special role for interactions of Ni, thiols, and Zn release.