Estrogen and progestin crosstalk via binding of PR at estrogen response elements

今年将有大约27万名妇女被诊断出患有乳腺癌，大约4万名妇女将死亡。 肺癌的死亡率仅次于肺癌。类固醇激素如女性性类固醇， 雌激素和孕激素在许多器官的正常发育和体内平衡中起关键作用， 特别是乳腺和子宫以及这些组织的癌症。我们对信号机制的理解 使用类固醇的人数显著增长尽管如此，即使是对“经典”的行动模式的调查， 类固醇受体继续揭示出令人惊讶的复杂性，特别是在不同受体之间的串扰中。 荷尔蒙虽然雌激素受体和孕激素受体（PR）被认为是单独结合的， DNA中不同的靶位点，我们发现PR与雌激素结合 反应元件（ERE）在体外和体内。在此过程中，PR抑制雌激素介导的基因诱导 雌激素靶点的一个子集，包括pS2，双调蛋白，C3和TERT。这种抑制似乎并不 主要是由于在ERE的竞争，而是，相反，因为企业公关复杂的不同 当结合在ERE而不是PRE时，因此，我们认为DNA是一种功能性配体， PR.作为推论，我们认为PR抑制雌激素介导的基因诱导的能力是由于 PR将辅阻遏物NCoR和/或SMRT募集到基因中。 这些假设。目的一是系统研究靶序列和激素对细胞凋亡的影响 结合染色质免疫组化和报告基因检测配体对PR功能的影响 测定。目的两个测试预测PR结合到ERE是构象不同的，通过组合 蛋白水解测定和X射线晶体学。在目标三中，这些数据的全球影响将是 探讨了微阵列分析将用于确定一组雌激素诱导基因抑制配体 PR，并选择候选人进行进一步的机理分析。目标四将具体测试 孕酮对雌激素介导的诱导的抑制是通过募集NCoR、SMRT或 在本申请中，我们提供了孕酮受体作用的新观点， 提出实验，以确定这两种机制和更广泛的后果，这些机制对 孕激素和雌激素的相互作用。

Approximately 270,000 women will be diagnosed with breast cancer this year and about 40,000 women will die of the disease, second in mortality only to lung cancer. Steroid hormones such as the female sex steroids, estrogen and progesterone, play critical roles in normal development and homeostasis of many organs, particularly breast and uterus and cancers of these tissues. Our understanding of the signaling mechanisms used by steroids has grown remarkably. Nonetheless, investigation of even the "classic" mode of action of steroid receptors continues to reveal surprising complexity, particularly in the crosstalk between different hormones. Although the estrogen receptor and progesterone receptor (PR) are thought to bind separate and distinct sets of target sites in the DNA, we have made the surprising observation that PR binds to estrogen response elements (EREs) both in vitro and in vivo. In doing so, PR inhibits estrogen-mediated gene induction at a subset of estrogen targets including pS2, amphiregulin, C3 and TERT. This inhibition does not appear to be primarily due to competition at the ERE but is, instead, because the hormone-PR complex differs functionally when bound at an ERE instead of a PRE. Thus, we propose that DNA is a functional ligand for PR. As a corollary, we propose that the ability of the PR to inhibit estrogen-mediated gene induction is due to the recruitment of the corepressors NCoR and/or SMRT to the gene by PR. Four aims are proposed to test these hypotheses. Aim one will systematically investigate the influence of target sequence and hormonal ligands on the function of PR using a combination of chromatin immunoprecipi-tation and reporter gene assays. Aim two tests the prediction that PR bound to an ERE is conformationally distinct via a combination of proteolytic assays and by x-ray crystallography. In aim three the global ramifications of these data will be explored. Microarray analyses will be used to define the set of estrogen-inducible genes inhibited by liganded PR and to select candidates for further mechanistic analysis. Aim four will specifically test whether the inhibition of estrogen-mediated induction by progesterone is through the recruitment of NCoR, SMRT, or associated HDACs by PR. In this application we offer a novel view of progesterone receptor action and propose experiments to define both mechanisms and the broader consequences of these mechanisms on the interactions of progestins and estrogens.