Van Luyn M J, Müller M, Renes J, Meijer C, Scheper R J, Nienhuis E F, Mulder N H, Jansen P L, De Vries E G
Department of Cell Biology, University Hospital Groningen, The Netherlands.
Int J Cancer. 1998 Mar 30;76(1):55-62. doi: 10.1002/(sici)1097-0215(19980330)76:1<55::aid-ijc10>3.0.co;2-f.
Intracellular glutathione-conjugate transport was evaluated in the human small cell lung carcinoma cell line GLC4 with low multidrug resistance protein (MRP1) expression and its 300x doxorubicin-resistant, MRP1-over-expressing, GLC4-Adr subline. Transport of non-toxic concentrations of monochlorobimane and 5-chloro-methyl fluorescein diacetate was evaluated using fluorescence microscopy. After exposure to these compounds, fluorescence was observed especially in intracellular vesicles in GLC4-Adr. Immunotransmission electron microscopy showed that MRP1 was present in the vesicle membranes and plasma membrane, while inside the vesicles the glutathione conjugate of 1-chloro-2,4-dinitrobenzene could be detected. Experiments with brefeldin A, which induces arrest in vesicle release from the Golgi complex, indicated that these vesicles may originate from the trans-Golgi network. In GLC4-Adr cells, doxorubicin also was transported in vesicles, with an arrest in vesicle release from the Golgi complex. Our results indicate that MRP1 functions as a glutathione-conjugate transporter not only at the plasma membrane but also in intracellular secretory vesicles.
在低多药耐药蛋白（MRP1）表达的人小细胞肺癌细胞系GLC4及其对阿霉素耐药300倍、MRP1过表达的GLC4-Adr亚系中评估细胞内谷胱甘肽结合物转运。使用荧光显微镜评估无毒浓度的单氯双香豆素和5-氯甲基荧光素二乙酸酯的转运。暴露于这些化合物后，在GLC4-Adr的细胞内囊泡中尤其观察到荧光。免疫透射电子显微镜显示MRP1存在于囊泡膜和质膜中，而在囊泡内部可检测到1-氯-2,4-二硝基苯的谷胱甘肽结合物。用布雷菲德菌素A进行的实验表明，其诱导从高尔基体复合物释放囊泡的过程停滞，这表明这些囊泡可能起源于反式高尔基体网络。在GLC4-Adr细胞中，阿霉素也通过囊泡转运，且从高尔基体复合物释放囊泡的过程停滞。我们的结果表明，MRP1不仅在质膜上而且在细胞内分泌囊泡中作为谷胱甘肽结合物转运体发挥作用。
