Garrick Michael D, Singleton Steven T, Vargas Farida, Kuo H-C, Zhao Lin, Knöpfel Martin, Davidson Todd, Costa Max, Paradkar Prasad, Roth Jerome A, Garrick Laura M
Department of Biochemistry, SUNY at Buffalo, Buffalo, NY 14214, USA.
Biol Res. 2006;39(1):79-85. doi: 10.4067/s0716-97602006000100009.
DMT1-Divalent Metal (Ion) Transporter 1 or SLC11A2/DCT1/Nramp2 - transports Fe2+ into the duodenum and out of the endosome during the transferrin cycle. DMTI also is important in non-transferrin bound iron uptake. It plays similar roles in Mn2+ trafficking. Voltage clamping showed that six other metals evoked currents, but it is unclear if these metals are substrates for DMT1. This report summarizes progress on which metals DMT1 transports, focusing on results from the authors' labs. We recently cloned 1A/+IRE and 2/-IRE DMT1 isoforms to generate HEK293 cell lines that express them in a tetracycline-inducible fashion, then compared induced expression to uninduced expression and to endogenous DMT1 expression. Induced expression increases approximately 50x over endogenous expression and approximately 10x over uninduced levels. Fe2+, Mn2+, Ni2+ and Cu1+ or Cu2+ are transported. We also explored competition between metal ions using this system because incorporation essentially represents DMT1 transport and find this order for transport affinity: Mn>?Cd>?Fe>Pb-Co-Ni>Zn. The effects of decreased DMT1 also could be examined. The Belgrade rat has diminished DMT1 function and thus provides ways of testing. A series of DNA constructs that generate siRNAs specific for DMT1 or certain DMT1 isoforms yield another way to test DMT1-based transport.
二价金属离子转运体1（DMT1）或溶质载体家族11成员2（SLC11A2）/二价阳离子转运体1（DCT1）/天然抗性相关巨噬细胞蛋白2（Nramp2）——在转铁蛋白循环过程中将亚铁离子转运到十二指肠并从内体转运出来。DMT1在非转铁蛋白结合铁的摄取中也很重要。它在锰离子的转运中发挥类似作用。电压钳实验表明，其他六种金属也能诱发电流，但尚不清楚这些金属是否是DMT1的底物。本报告总结了关于DMT1转运哪些金属的研究进展，重点介绍了作者实验室的研究结果。我们最近克隆了1A/+IRE和2/-IRE DMT1异构体，以生成能以四环素诱导方式表达它们的人胚肾293（HEK293）细胞系，然后将诱导表达与未诱导表达以及内源性DMT1表达进行比较。诱导表达比内源性表达增加约50倍，比未诱导水平增加约10倍。亚铁离子、锰离子、镍离子以及亚铜离子或铜离子均可被转运。我们还利用该系统探索了金属离子之间的竞争，因为摄取本质上代表了DMT1的转运，并发现了如下转运亲和力顺序：锰＞镉＞铁＞铅-钴-镍＞锌。DMT1功能降低的影响也可以进行研究。贝尔格莱德大鼠的DMT1功能减弱，因此提供了测试方法。一系列能产生针对DMT1或某些DMT1异构体的小干扰RNA（siRNA）的DNA构建体，为测试基于DMT1的转运提供了另一种方法。
