Faus Hortensia, Meyer Hellmuth-Alexander, Huber Martina, Bahr Inke, Haendler Bernard
Corporate Research Oncology, Schering AG, D-13342 Berlin, Germany.
Mol Cell Endocrinol. 2005 Dec 21;245(1-2):138-46. doi: 10.1016/j.mce.2005.11.011. Epub 2005 Dec 20.
The role of the ubiquitin/proteasome system in degrading nuclear hormone receptors and regulating their transcriptional function has emerged in the last few years. We identified the ubiquitin-specific protease USP10 as part of DNA-bound androgen receptor (AR) complexes purified from nuclear extracts of PC-3 cells stably expressing the AR. The interaction between USP10 and the AR was confirmed by GST pull-down assays. Fluorescence microscopy documented that USP10 was localised in the nucleus and the cytoplasm. Cell-based transactivation assays in PC-3/AR cells revealed that overexpression of wild-type USP10, but not of an enzymatically inactive form, stimulated AR activity mediated by reporter constructs harbouring selective androgen response elements (AREs), non-selective steroid response elements (SREs) or the mouse mammary tumour virus (MMTV) promoter. Conversely, USP10 expression knock-down by siRNAs impaired the MMTV response to androgen. In summary, the data indicate that USP10 is a new cofactor that binds to the AR and stimulates the androgen response of target promoters. This finding underlines the role of the ubiquitin/proteasome system in modulating the AR function.
泛素/蛋白酶体系统在降解核激素受体及调节其转录功能方面的作用在过去几年中逐渐显现。我们从稳定表达雄激素受体（AR）的PC-3细胞的核提取物中纯化出与DNA结合的AR复合物，鉴定出泛素特异性蛋白酶USP10是其中一部分。通过谷胱甘肽-S-转移酶（GST）下拉实验证实了USP10与AR之间的相互作用。荧光显微镜检查表明USP10定位于细胞核和细胞质中。在PC-3/AR细胞中进行的基于细胞的反式激活实验显示，野生型USP10（而非无酶活性形式）的过表达刺激了由携带选择性雄激素反应元件（AREs）、非选择性类固醇反应元件（SREs）或小鼠乳腺肿瘤病毒（MMTV）启动子的报告基因构建体介导的AR活性。相反，通过小干扰RNA（siRNAs）敲低USP10的表达会损害MMTV对雄激素的反应。总之，数据表明USP10是一种新的辅助因子，它与AR结合并刺激靶启动子的雄激素反应。这一发现强调了泛素/蛋白酶体系统在调节AR功能中的作用。
