Metal-metal interaction mediates the iron induction of Drosophila MtnB
Metal-metal interaction mediates the iron induction of Drosophila MtnB
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金属-金属相互作用介导果蝇 MtnB 的铁诱导
DOI：
10.1016/j.bbrc.2017.04.109
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发表时间：
2017
影响因子：
3.1
通讯作者：
Zhou Bing
中科院分区：
文献类型：
--
作者：
Qiang Wenjia;Huang Yunpeng;Wan Zhihui;Zhou Bing
金属硫蛋白家族是一类富含半胱氨酸残基的小而通用的蛋白质。它们是在响应重金属应力的情况下合成的，通过金属硫酸盐桥接来隔离有毒离子。在果蝇中已经发现并鉴定了MtnA、MtnB、MtnC、MtnD和MtnE五个MT家族成员。MTs的这五种亚型受金属响应转录因子dMTF-1的调控，在金属离子解毒过程中发挥不同但重叠的作用。先前的研究表明，果蝇mtnb对铜（Cu）、镉（Cd）和锌（Zn）有反应。有趣的是，在这项研究中，我们发现果蝇的mtn表达也会对饮食中铁含量的升高做出反应。进一步的研究表明，MtnB在铁解毒中的作用有限，并且MtnB与亚铁的直接结合也很弱。铁对MtnB的诱导被证明是由其他金属的铁干扰介导的，因为EDTA即使是铁的部分浓度也可以抑制这种诱导。事实上，在铁的存在下，锌的体内平衡被改变，这反映在锌转运蛋白zip1和dznt1的表达变化上。因此，铁介导的MtnB诱导似乎是由于锌等其他金属的体内平衡中断，而锌反过来又诱导MtnB表达。金属-金属相互作用可能比我们预期的更为广泛地存在。
Metallothionein (MT) protein families are a class of small and universal proteins rich in cysteine residues. They are synthesized in response to heavy metal stresses to sequester the toxic ions by metal-thiolate bridges. Five MT family members, namely MtnA, MtnB, MtnC, MtnD and MtnE, have been discovered and identified inDrosophila. These five isoforms of MTs are regulated by metal responsive transcription factor dMTF-1 and play differentiated but overlapping roles in detoxification of metal ions. Previous researches have shown thatDrosophila MtnBresponds to copper (Cu), cadmium (Cd) and zinc (Zn). Interestingly in this study we found thatDrosophila MtnBexpression also responds to elevated iron levels in the diet. Further investigations revealed thatMtnBplays limited roles in iron detoxification, and the direct binding of MtnB to ferrous ironin vitrois also weak. The induction of MtnB by iron turns out to be mediated by iron interference of other metals, because EDTA at even a partial concentration of that of iron can suppress this induction. Indeed, in the presence of iron, zinc homeostasis is altered, as reflected by expression changes of zinc transportersdZIP1anddZnT1. Thus, iron-mediated MtnB induction appears resulting from interrupted homeostasis of other metals such as zinc, which in turns induced MtnB expression. Metal-metal interaction may more widely exist than we expected.