Multiple mechanisms of ligand interaction with the human organic cation transporter, OCT2
Multiple mechanisms of ligand interaction with the human organic cation transporter, OCT2
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DOI：
10.1152/ajprenal.00486.2012
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发表时间：
2013-01-01
影响因子：
4.2
通讯作者：
Wright, Stephen H.
中科院分区：
文献类型：
--
作者：
Harper, Jaclyn N.;Wright, Stephen H.
王丽娟，王晓华。有机阳离子转运体OCT2与配体相互作用的多种机制。[J] .中华医学杂志，2013,31(4):556 - 567。2012年10月3日首次发表；doi: 10.1152 / ajprenal.00486.2012。-OCT2是肾近端小管分泌有机阳离子（OC）的进入步骤。虽然许多药物抑制OCT2活性，但其抑制的机制基础和运输状态都不为人所知。Kido Y, Matsson P, Giacomini KM.利用最近描述的几种oct2抑制配体的结构类别的代表。中国医学杂志54:4548-4558,2011)，我们确定了它们抑制1-甲基-4-苯基吡啶（MPP）转运到稳定表达hOCT2的中国仓鼠卵巢细胞的动力学基础。“簇II”抑制剂（含有已知的OCT2底物）二甲双胍和西咪替丁与MPP竞争性相互作用。然而，其他簇II化合物，包括四乙基铵（TEA）、二苯醇和苯羟洛胺，是MPP转运的混合型抑制剂（即降低J（max）和增加K-t）。第III类（中性类固醇）代表肾上腺素酮和第I类（大而灵活的阳离子）代表卡维地洛显示出非竞争性抑制谱。竞争逆流法（CCF）测定了抑制配体是否作为hOCT2的底物。卡维地洛（I类）和肾上腺素酮（III类）不支持CCF，这与这些结构类的成员可能是OCT2的非转运抑制剂的预测一致。第二组代表MPP、二甲双胍、西咪替丁和TEA均支持CCF，这与对其oct2介导转运的独立评估一致。然而，簇II的其他代表物，苯苯多酚和苯妥拉明，未能支持CCF，这表明这两种化合物都不是通过OCT2运输的。一项对二苯idol转运的独立评估（使用液相色谱和串联质谱）证实了这一观察结果。这些结果强调了在开发配体与多药物转运体相互作用的预测模型时需要谨慎。
Harper JN, Wright SH. Multiple mechanisms of ligand interaction with the human organic cation transporter, OCT2. Am J Physiol Renal Physiol 304: F56-F67, 2013. First published October 3, 2012; doi:10.1152/ajprenal.00486.2012.-OCT2 is the entry step for organic cation (OC) secretion by renal proximal tubules. Although many drugs inhibit OCT2 activity, neither the mechanistic basis of their inhibition nor their transport status is generally known. Using representatives of several structural classes of OCT2-inhibitory ligands described recently (Kido Y, Matsson P, Giacomini KM. J Med Chem 54: 4548-4558, 2011), we determined the kinetic basis of their inhibition of 1-methyl-4-phenylpyridinium (MPP) transport into Chinese hamster ovary cells that stably expressed hOCT2. The "cluster II" inhibitors (which contain known OCT2 substrates) metformin and cimetidine interacted competitively with MPP. However, other cluster II compounds, including tetraethylammonium (TEA), diphenidol and phenyltoloxamine, were mixed-type inhibitors of MPP transport (i.e., decreasing J(max) and increasing K-t). A cluster III (neutral steroid) representative, adrenosterone, and a cluster I (large, flexible cation) representative, carvedilol, displayed noncompetitive inhibitory profiles. Competitive counterflow (CCF) was used to determine whether the inhibitory ligands served as substrates of hOCT2. Carvedilol (cluster I) and adrenosterone (cluster III) did not support CCF, consistent with the prediction that members of these structural classes are likely to be nontransported inhibitors of OCT2. The cluster II representatives MPP, metformin, cimetidine, and TEA all supported CCF, consistent with independent assessments of their OCT2-mediated transport. However, the other cluster II representatives, diphenidol and phenyltoloxamine, failed to support CCF, suggesting that neither compound is transported by OCT2. An independent assessment of diphenidol transport (using liquid chromatography with tandem mass spectroscopy) confirmed this observation. The results underscore the caution required for development of predictive models of ligand interaction with multidrug transporters.