el-Ashry D, Oñate S A, Nordeen S K, Edwards D P
Department of Pathology, University of Colorado Health Sciences Center, Denver 80262.
Mol Endocrinol. 1989 Oct;3(10):1545-58. doi: 10.1210/mend-3-10-1545.
Structural and functional properties of human progesterone receptors (PR) bound with the antiprogestin, RU 486, and the progestin agonist, R5020, were compared in order to identify receptor mechanisms responsible for the inability of RU 486 to activate the transcriptional capacity of receptors. RU 486 interaction with human PR did not inhibit receptor transformation as assessed by dissociation of nontransformed 8-10S oligomeric receptors (in vitro and in vivo) and by tight binding of PR to nuclei/chromatin in whole cells. Assays based on immunoprecipitation of PR-DNA complexes with an antibody to human PR and gel retardation were used to analyze the effect of RU 486 on receptor binding to the hormone response element (HRE) of the mouse mammary tumor virus (MMTV). RU 486 did not impair PR recognition of the MMTV HRE. Quantitative affinity constants and kinetic parameters of PR binding to these specific DNA sites were similar for receptors complexed with either agonist or antagonist. However, PR-RU 486 complexes exhibited an altered sedimentation rate on sucrose gradients and a faster mobility when bound to the MMTV HRE as assessed by gel retardation. These results indicate that human PR transformed by RU 486 exhibit no impairment in binding to specific DNA sites of target genes, but when bound to DNA assumes a structural form different from that of the receptor-agonist complexes to activate transcription results from this structural alteration in PR, which does not permit protein-protein interactions required for receptor-mediated induction of gene transcription.
比较了与抗孕激素RU 486及孕激素激动剂R5020结合的人孕激素受体（PR）的结构和功能特性，以确定导致RU 486无法激活受体转录能力的受体机制。通过非转化的8 - 10S寡聚受体的解离（体外和体内）以及PR与全细胞核/染色质的紧密结合评估，RU 486与人PR的相互作用并未抑制受体转化。基于用人PR抗体免疫沉淀PR - DNA复合物和凝胶阻滞的实验，用于分析RU 486对受体与小鼠乳腺肿瘤病毒（MMTV）激素反应元件（HRE）结合的影响。RU 486并未损害PR对MMTV HRE的识别。与激动剂或拮抗剂复合的受体与这些特定DNA位点结合的定量亲和常数和动力学参数相似。然而，通过凝胶阻滞评估，PR - RU 486复合物在蔗糖梯度上表现出改变的沉降速率，并且与MMTV HRE结合时迁移率更快。这些结果表明，由RU 486转化的人PR在与靶基因特定DNA位点结合方面没有受损，但与DNA结合时呈现出与受体 - 激动剂复合物不同的结构形式，PR的这种结构改变导致无法激活转录，因为这种改变不允许受体介导的基因转录诱导所需的蛋白质 - 蛋白质相互作用。
