The mitochondrial fluorescent dye rhodamine 123 is a high-affinity substrate for organic cation transporters (OCTs) 1 and 2
The mitochondrial fluorescent dye rhodamine 123 is a high-affinity substrate for organic cation transporters (OCTs) 1 and 2
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DOI：
10.1111/j.1472-8206.2012.01071.x
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发表时间：
2014-02-01
影响因子：
2.9
通讯作者：
Fardel, Olivier
中科院分区：
文献类型：
--
作者：
Jouan, Elodie;Le Vee, Marc;Fardel, Olivier
罗丹明123是一种荧光阳离子染料，通常用作线粒体探针，已知或怀疑由某些药物膜转运蛋白转运。本研究旨在表征罗丹明123与人有机阳离子转运蛋白（OCT）1和OCT 2的假定相互作用。与对照HEK 293细胞相比，hOCT 1和hOCT 2过表达HEK 293细胞中染料的细胞内摄取均增强。发现罗丹明123流入量的增加是可饱和载体介导的过程，具有低K-m值（对于hOCT 1和hOCT 2阳性HEK 293细胞中染料的转运，K-m分别=0.54 μ m和K-m=0.61 μ m）。接下来证明了已知的hOCT 1和hOCT 2活性抑制剂，如维拉帕米、阿米替林、哌唑嗪和奎宁，可降低hOCT 1和hOCT 2过表达的HEK 293细胞中罗丹明123的蓄积。此外，染料被发现抑制hOCT 1和hOCT 2介导的摄取四乙铵（TEA），模型底物hOCT 1和hOCT 2;罗丹明123似乎是一个更有效的抑制剂hOCT 1介导的TEA运输（IC 50 =0.37 μ m）比hOCT 2介导的（IC 50 =61.5 μ m）。总之，这些数据表明，罗丹明123是一个高亲和力的hOCT 1和hOCT 2的底物。因此，这种染料可能是有用的荧光调查细胞hOCT 1或hOCT 2的活性，知道，然而，其他因素可能有助于细胞积累的罗丹明123，包括线粒体膜电位或外排转运蛋白P-糖蛋白的表达，也要考虑。
Rhodamine 123 is a fluorescent cationic dye commonly used as a mitochondrial probe and known or suspected to be transported by certain drug membrane transporters. The present study was designed to characterize the putative interactions of rhodamine 123 with human organic cation transporter (OCT) 1 and OCT2. Intracellular uptake of the dye was demonstrated to be enhanced in both hOCT1- and hOCT2-overexpressing HEK293 cells when compared with control HEK293 cells. This increase of rhodamine 123 influxes was found to be a saturable carrier-mediated process, with low K-m values (K-m=0.54 mu m and K-m=0.61 mu m for transport of the dye in hOCT1- and hOCT2-positive HEK293 cells, respectively). Known inhibitors of hOCT1 and hOCT2 activities such as verapamil, amitriptyline, prazosin, and quinine were next demonstrated to decrease rhodamine 123 accumulation in hOCT1- and hOCT2-overexpressing HEK293 cells. In addition, the dye was found to inhibit hOCT1- and hOCT2-mediated uptake of tetraethylammonium (TEA), a model substrate for both hOCT1 and hOCT2; rhodamine 123 appeared nevertheless to be a more potent inhibitor of hOCT1-mediated TEA transport (IC50=0.37 mu m) than of that mediated by hOCT2 (IC50=61.5 mu m). Taken together, these data demonstrate that rhodamine 123 is a high-affinity substrate for both hOCT1 and hOCT2. This dye may be therefore useful for fluorimetrically investigating cellular hOCT1 or hOCT2 activity, knowing, however, that other factors potentially contributing to cellular accumulation of rhodamine 123, including mitochondrial membrane potential or expression of the efflux transporter P-glycoprotein, have also to be considered.