van den Berg J D, Smets L A, van Rooij H
Division of Experimental Therapy, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
J Steroid Biochem Mol Biol. 1996 Feb;57(3-4):239-49. doi: 10.1016/0960-0760(95)00271-5.
Nuclear translocation of activated glucocorticoid receptors (GRs) is a necessary step in the signal transduction by these GC hormones. Although in vitro activation of GRs can occur in the absence of a functional ligand, it is generally assumed that binding of a cognate hormone is required for activation of the intracellular GR. By indirect immunocytochemistry and Western-blot analysis, it was found that, in spontaneously aggregated human lymphoma DoHH2 cells, hormone-free GRs are located in the nucleus. Disruption of the aggregates redistributed GRs to a predominantly cytosolic location. Upon spontaneous re-aggregation the GR again became localized to the nucleus. Intracellular cross-linking of the heteromeric receptor complex was applied to investigate the protein composition of cytoplasmic and nuclear receptors. Untransformed, cytosolic GRs could be demonstrated by [3H]dexamethasone binding capacity and hsp90 co-immunoprecipitation, whereas absence of these characteristics suggested an activated conformation of the nuclear GRs. These observations suggest that cell-cell interactions are capable of transforming GRs in the absence of a ligand.
活化糖皮质激素受体（GRs）的核转位是这些糖皮质激素（GC）信号转导过程中的必要步骤。尽管在没有功能性配体的情况下，GRs在体外也能被激活，但一般认为，细胞内GRs的激活需要同源激素的结合。通过间接免疫细胞化学和蛋白质印迹分析发现，在自发聚集的人淋巴瘤DoHH2细胞中，无激素的GRs位于细胞核中。聚集物的破坏使GRs重新分布到主要位于细胞质的位置。自发重新聚集后，GRs再次定位于细胞核。应用异源受体复合物的细胞内交联来研究细胞质和细胞核受体的蛋白质组成。未转化的细胞质GRs可通过[3H]地塞米松结合能力和hsp90共免疫沉淀来证明，而缺乏这些特征则表明细胞核GRs处于活化构象。这些观察结果表明，细胞间相互作用能够在没有配体的情况下使GRs发生转化。
