Molecular chaperones function as steroid receptor nuclear mobility factors
Molecular chaperones function as steroid receptor nuclear mobility factors
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DOI：
10.1073/pnas.0400116101
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发表时间：
2004-03-02
影响因子：
11.1
通讯作者：
DeFranco, DB
中科院分区：
文献类型：
--
作者：
Elbi, C;Walker, DA;DeFranco, DB
活细胞成像揭示了类固醇激素受体在细胞核内的快速流动性及其在转录活性靶位点的动态交换。尽管许多其他蛋白质已被证明在细胞核内具有高度移动的性，但负责协调核运输的可溶性因子的身份仍然未知。我们已经开发了一种以前未描述的原位亚核贩运试验，产生转录活性核，这是耗尽糖皮质激素（GR）和孕酮受体（PR）的核流动性所需的可溶性因子。使用这个系统和荧光恢复后的光漂白技术，我们表明，核迁移率的GR恢复与网织红细胞裂解物孵育抑制格尔德霉素，一种药物，阻断伴侣活性的热休克蛋白90。直接证据分子伴侣参与类固醇受体亚核贩运提供了ATIP依赖性恢复的GR和PR的核流动性孵育与各种组合的纯化伴侣和/或cochaperone蛋白。此外，对于这两种受体，在恢复期间包含激素导致核移动性的阻滞。因此，我们的研究结果提供了一个可溶性核流动性因子的描述，并进一步证明了以前未被认识到的作用，分子伴侣在细胞核内的类固醇受体功能的调节。
Live cell imaging has revealed the rapid mobility of steroid hormone receptors within nuclei and their dynamic exchange at transcriptionally active target sites. Although a number of other proteins have been shown to be highly mobile within nuclei, the identity of soluble factors responsible for orchestrating nuclear trafficking remains unknown. We have developed a previously undescribed in situ subnuclear trafficking assay that generates transcriptionally active nuclei, which are depleted of soluble factors required for the nuclear mobility of glucocorticoid (GR) and progesterone receptors (PR). Using this system and a fluorescence recovery after photobleaching technique, we demonstrate that nuclear mobility of GR recovered on incubation with reticulocyte lysate was inhibited by geldanamycin, a drug that blocks the chaperone activity of heat-shock protein 90. Direct proof of molecular chaperone involvement in steroid receptor subnuclear trafficking was provided by the ATIP-dependent recovery of nuclear mobility of GR and PR on incubation with various combinations of purified chaperone and/or cochaperone proteins. Additionally, for both receptors, the inclusion of hormone during the recovery period leads to a retardation of nuclear mobility. Thus, our results provide a description of soluble nuclear mobility factors and furthermore demonstrate a previously unrecognized role for molecular chaperones in the regulation of steroid receptor function within the nucleus.