Mechanisms for glucocorticoid vs. progesterone receptor-specific gene regulation

对于相同细胞中相同基因的 GR 和 PR 诱导，辅阻遏物 NCoR 和 SMRT 已被证明对激动剂的 EC50 和拮抗剂的残余激动剂活性量具有相反的影响。 这些反向反应取决于每个受体的 N 端和 C 端结构域的联合作用（Song 等人，2001，J. Biol. Chem., 276, 24806-24816）。 这些结果与以下事实一致：除了受体 C 端序列中最初定义的位点外，辅阻遏物还与 GR 和 PR 的 N 端区域相互作用（Wang 等人，2007，Biochemistry，48, 8036-8049；Wang 和 Simons Jr.，2005，Mol. Endo.，19，1483-1500）。 类似地，最近发现其他四个已知调节 GR 活性的因子（GME、GMEB2、Ubc9 和 STAMP）要么在其他相同的条件下差异性地改变 GR 与 PR 的几个诱导参数，要么需要每个受体的不同区域来发挥其活性（Szapary 等人，2008，Mol Cell Endocrinol，283, 114-126）。 本研究的目的是检查已知调节瞬时转染 GR 与 PR 复合物的 EC50、部分激动剂活性百分比和 Amax 的其他因素的影响，以进一步定义负责 GR 和 PR 不同生物作用的参数。 目前正在使用全细胞生物测定来确定两种新调节因子的调节活性，同时进行 ChIP 测定来辨别这些因子的存在是否改变了几种常见转录因子向内源调节基因相关区域的募集。 当这些研究完成后，我们将用 PR 进行类似的实验，以识别相似和不同的分子作用。 这些研究有助于我们在分子水平上定义类固醇激素的作用并了解它们在人类生理学中的作用的长期目标。

The corepressors NCoR and SMRT have been documented to have opposite effects on the EC50 of agonists, and the amount of residual agonist activity of antagonists, for GR and PR induction of the same gene in the same cells. These inverted responses depend upon the joint actions of the N- and C-terminal domains of each receptor (Song et al., 2001, J. Biol. Chem., 276, 24806-24816). These results are consistent with the demonstration that corepressors interact with N-terminal regions of both GRs and PRs (Wang et al., 2007, Biochemistry, 48, 8036-8049; Wang and Simons Jr., 2005, Mol. Endo., 19, 1483-1500) in addition to the initially defined sites in the C-terminal sequences of receptors. Similarly, four other factors known to modulate GR activity (GME, GMEB2, Ubc9, and STAMP) were recently found either to differentially alter several induction parameters of GRs vs. PRs under otherwise identical conditions or to require different regions of each receptor for their activities (Szapary et al., 2008, Mol Cell Endocrinol, 283, 114-126). The objective of this study is to examine the consequences of other factors known to modulate the EC50, percent partial agonist activity, and Amax of transiently transfected GR vs. PR complexes to further define the parameters responsible for the different biological actions of GRs and PRs. Whole cells bioassays are currently being used to determine the modulatory activity of two new modulatory factors, while ChIP assays are being performed to discern whether the presence of these factors alters the recruitment of several common transcription factors to relevant regions of endogenous regulated genes. When these studies are completed, we will perform similar experiments with PRs to identify similar and divergent molecular actions. These studies contribute to our long-term goal of defining the action of steroid hormones at a molecular level and of understanding their role in human physiology.