Verma Seema, Ismail Ayesha, Gao Xiuhua, Fu Guilian, Li Xiaotao, O'Malley Bert W, Nawaz Zafar
Cancer Center, Criss III, Room 352, Creighton University, 2500 California Plaza, Omaha, NE 68178, USA.
Mol Cell Biol. 2004 Oct;24(19):8716-26. doi: 10.1128/MCB.24.19.8716-8726.2004.
We investigated the role of the ubiquitin-conjugating enzyme UBCH7 in nuclear receptor transactivation. Using transient transfection assays, we demonstrated that UBCH7 modulates the transcriptional activity of progesterone receptor (PR) and glucocorticoid, androgen, and retinoic acid receptors in a hormone-dependent manner and that the ubiquitin conjugation activity of UBCH7 is required for its ability to potentiate transactivation by steroid hormone receptors (SHR). However, UBCH7 showed no significant effect on the transactivation functions of p53 and VP-16 activation domain. Depletion of endogenous UBCH7 protein by small interfering RNAs suggests that UBCH7 is required for the proper function of SHR. Furthermore, a chromatin immunoprecipitation assay demonstrated the hormone-dependent recruitment of UBCH7 onto estrogen receptor- and PR-responsive promoters. Additionally, we show that UBCH7 and E6-associated protein (E6-AP) synergistically enhance PR transactivation. We also demonstrate that UBCH7 interacts with steroid receptor coactivator 1 (SRC-1) and that UBCH7 coactivation function is dependent on SRC-1. Taken together, our results reveal the possible role of UBCH7 in steroid receptor transactivation and provide insights into the mechanism of action of UBCH7 in receptor function.
我们研究了泛素结合酶UBCH7在核受体反式激活中的作用。通过瞬时转染实验，我们证明UBCH7以激素依赖的方式调节孕酮受体（PR）、糖皮质激素受体、雄激素受体和视黄酸受体的转录活性，并且UBCH7的泛素结合活性是其增强类固醇激素受体（SHR）反式激活能力所必需的。然而，UBCH7对p53和VP - 16激活域的反式激活功能没有显著影响。用小干扰RNA耗尽内源性UBCH7蛋白表明，SHR的正常功能需要UBCH7。此外，染色质免疫沉淀实验证明了UBCH7在激素依赖的情况下被募集到雌激素受体和PR反应性启动子上。此外，我们发现UBCH7和E6相关蛋白（E6 - AP）协同增强PR的反式激活。我们还证明UBCH7与类固醇受体辅激活因子1（SRC - 1）相互作用，并且UBCH7的共激活功能依赖于SRC - 1。综上所述，我们的结果揭示了UBCH7在类固醇受体反式激活中的可能作用，并为UBCH7在受体功能中的作用机制提供了见解。
