Parikh I, Rajendran K G, Su J L, Lopez T, Sar M
Department of Biochemistry, Glaxo Research Laboratories, Research Triangle Park, NC 27709.
J Steroid Biochem. 1987;27(1-3):185-92. doi: 10.1016/0022-4731(87)90309-8.
The subcellular localization of estradiol receptor (ER) has been examined using various experimental approaches. Immunocytochemical studies using the monoclonal antibody JS 34/32, raised against calf uterine cytosolic ER, yielded only equivocal results. In general, cells and tissues pretreated with estradiol showed positive immunostaining in the nuclei whereas those not exposed to the steroid did not show any staining. Nuclear translocation of ER was examined in intact MCF-7 cells using compounds which are known to influence receptor activation. When MCF-7 cells were exposed to molybdate (20 mM), nuclear translocation was completely inhibited while dithiothreitol (20 mM), dibutyryl cAMP (1 microM) and dibutyryl cGMP (1 microM) increased the translocation 2-3-fold. Phenol red, at the range of concentrations generally used in tissue culture media, also increased translocation. The physiological validity of such translocation was examined using cellular progesterone receptor (PR) synthesis as a specific parameter. When MCF-7 cells were grown in media containing phenol red for 48 h, the PR synthesis increased significantly. We further examined whether cytoskeletal proteins are involved in the translocation of ER. Colchicine, an inhibitor of microtubule assembly, inhibited translocation of ER in MCF-7 cells at 1-10 microM. PR synthesis was also inhibited by colchicine in a dose-dependent manner. It may be concluded from these and other published data that ER may not be located at all times in a single subcellular compartment but may rather exist in a dynamic equilibrium between the plasma membrane, cytoplasm and nucleus.
已使用各种实验方法研究了雌二醇受体（ER）的亚细胞定位。使用针对小牛子宫胞质ER产生的单克隆抗体JS 34/32进行的免疫细胞化学研究仅得到了模棱两可的结果。一般来说，用雌二醇预处理的细胞和组织在细胞核中显示出阳性免疫染色，而未暴露于该类固醇的细胞和组织则未显示任何染色。使用已知会影响受体激活的化合物在完整的MCF-7细胞中检测了ER的核转位。当MCF-7细胞暴露于钼酸盐（20 mM）时，核转位被完全抑制，而二硫苏糖醇（20 mM）、二丁酰环磷酸腺苷（1 microM）和二丁酰环磷酸鸟苷（1 microM）使转位增加了2至3倍。在组织培养基中常用的浓度范围内，酚红也增加了转位。使用细胞孕酮受体（PR）合成作为特定参数来检测这种转位的生理有效性。当MCF-7细胞在含有酚红的培养基中生长48小时时，PR合成显著增加。我们进一步研究了细胞骨架蛋白是否参与ER的转位。秋水仙碱是一种微管组装抑制剂，在1至10 microM时可抑制MCF-7细胞中ER的转位。秋水仙碱也以剂量依赖的方式抑制PR合成。从这些以及其他已发表的数据可以得出结论，ER可能并非始终位于单个亚细胞区室中，而是可能存在于质膜、细胞质和细胞核之间的动态平衡中。
