Evidence that the multidrug resistance protein (MRP) functions as a co-transporter of glutathione and natural product toxins.
Evidence that the multidrug resistance protein (MRP) functions as a co-transporter of glutathione and natural product toxins.
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发表时间：
1997-12
期刊：
影响因子：
11.2
通讯作者：
G. Rappa;A. Lorico;R. Flavell;A. Sartorelli
中科院分区：
文献类型：
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作者：
G. Rappa;A. Lorico;R. Flavell;A. Sartorelli
MRP（多药耐药蛋白）基因是普遍存在的atp结合盒转运蛋白超家族的一员，与哺乳动物细胞对天然产物抗癌药物的多药耐药有关。我们以前已经表明，通过基因靶向消除MRP表达导致对几种药物过敏。在两个独立生产的MRP双敲除克隆中，谷胱甘肽（GSH）的基线输出是野生型胚胎干（ES）细胞的一半。在依托opo苷（VP-16）和亚砷酸钠的存在下，野生型ES细胞的GSH输出增加，而MRP双敲除克隆细胞的GSH输出则增加，同时细胞内GSH水平也相应下降。在两个MRP双敲除克隆中，细胞内依托泊苷的稳态浓度比野生型细胞高两倍。D - l -丁硫氨酸亚砜对细胞内GSH的消耗增加了亲代ES细胞内放射性标记的依托泊苷的积累，达到了两个MRP敲除克隆中存在的水平，但没有改变MRP敲除克隆中的依托泊苷水平。这些观察结果提供了证据：(a) MRP从生理上输出谷胱甘肽，可能与内源性化合物有关；(b)基线MRP表达通过共运输机制将外源药物和谷胱甘肽从细胞内腔室外排到细胞外介质中，从而保护细胞免受外源药物的毒性作用；(c)破坏编码MRP的基因，消除了外源性药物和谷胱甘肽的共同运输。
The MRP (multidrug resistance protein) gene, a member of the ubiquitous superfamily of ATP-binding cassette transporters, is associated with the multidrug resistance of mammalian cells to natural product anticancer agents. We have previously shown that abrogation of MRP expression by gene targeting leads to hypersensitivity to several drugs. In two independently produced MRP double knockout clones, the baseline export of glutathione (GSH) was one-half that of wild-type embryonic stem (ES) cells. The export of GSH from wild-type ES cells, but not from the MRP double knockout clones, increased in the presence of etoposide (VP-16) and sodium arsenite, accompanied by equivalent decreases in intracellular levels of GSH. In the two MRP double knockout clones, the intracellular steady-state concentration of etoposide was twofold greater than that in wild-type cells. Depletion of intracellular GSH by D,L-buthionine sulfoximine increased the intracellular accumulation of radiolabeled etoposide in parental ES cells up to the level present in the two MRP knockout clones but did not change etoposide levels in the MRP knockout clones. These observations provide evidence that: (a) MRP exports GSH physiologically, presumably in association with an endogenous compound(s); (b) baseline MRP expression protects cells from the toxic effects of xenobiotics by effluxing the xenobiotics and GSH from the intracellular compartment into the extracellular medium by a co-transport mechanism; and (c) disruption of the gene encoding MRP abrogates the cotransport of xenobiotics and GSH.