HORMONAL REGULATION OF ANDROGEN RECEPTOR EXPRESSION

雄激素受体（AR）是一种配体激活的转录因子，与雄激素调节基因相关的雄激素反应元件（AREs）结合。AR对雄激素介导的男性性发育至关重要，并在前列腺癌的病因和进展中发挥作用。雄激素促进组织特异性AR mRNA的上调和下调，提示AR和细胞特异性因子在AR mRNA自动调节中的作用。本研究的主要目标是确定这些非AR因子，并确定它们对AR mRNA上调的贡献。由于雄激素反应性与AR水平相关，AR mRNA的自动调节可能在调节正常细胞和肿瘤细胞的激素敏感性中起关键作用。与这一观点一致，我们观察到雄激素介导的AR mRNA和蛋白上调与细胞雄激素敏感性增强有关。AR基因启动子和上游区域未被证明包含ARE和ARE-2，在AR基因内部6.5 kb雄激素响应区域的外显子中。这些Res位于由D和e外显子组成的350 bp的R cDNA片段上。在报告基因检测中，这两个6.5 kb和350 bp的片段表现出细胞特异性雄激素调控，反映了天然AR基因的上调。这四种AREs都是AR结合350 bp区域和AR mRNA转录上调所必需的。此外，与原生基因一样，尽管存在AREs，但6.5 kb和350 bp区域不受糖皮质激素和糖皮质激素受体（GR）的调节。类似于激素反应元件（HRE）共识序列。在其他几个基因中，HREs受到GR的结合和调控。本提案的目的是利用体内足迹技术来检测AR、GR和非受体因子与6.5 kb雄激素反应区外显子D和E的结合，这些外显子作为稳定整合的模板存在。我们将确定在雄激素反应区活跃与不活跃的细胞中，受体和核因子结合模式对雄激素（和糖皮质激素）的反应是否不同。我们将识别和表征差异结合的非受体因子，并确定该因子在细胞和雄激素特异性AR mRNA上调中的作用。这些研究的长期目标是提供rmrna自我调节机制的全面物理和功能特征，并将这些机制与正常细胞和肿瘤细胞的激素反应联系起来。

The androgen receptor (AR) is a ligand-activated transcription factor that binds to androgen responsive elements (AREs) associated with androgen- regulated genes. AR is essential for androgen mediated male sexual development and plays a role in prostate cancer etiology and progression. Androgen promotes tissue-specific up- an down-regulation of AR mRNA, suggesting roles for both AR and cell-specific factors in AR mRNA autoregulation. Key goals of this proposal are to identify these non-AR factors and to define their contribution to AR mRNA up-regulation. Because androgen responsiveness is related to AR levels, autoregulation of AR mRNA may be critical in modulating hormonal sensitivity in normal and neoplastic cells. Consistent with this idea, we observed that androgen- mediated up-regulation of AR mRNA and protein is associated with enhanced cellular androgen sensitivity. The AR gene promoter and upstream region have not been demonstrated to contain the ARE and ARE-2, in exons of an internal 6.5 kb androgen responsive region of the AR gene. These Res are located on a 350 bp fragment of the R cDNA that consists of exons D and E. Both the 6.5 kb and 350 bp fragments exhibit cell-specific androgen regulation in reporter gene assays that mirrors up-regulation of the native AR gene. All four AREs are required for AR binding to the 350 bp region and for transcriptional up-regulation of AR mRNA. Furthermore, like the native gene, the 6.5 kb and 350 bp regions are not regulated by glucocorticoid and glucocorticoid receptor (GR) despite the presence of AREs. Resembling the hormone response element (HRE) consensus sequence. HREs are bound and regulated by GR in several other genes. The aims of this proposal are to utilize in vivo foot-printing techniques to examine binding of AR, GR and non-receptor factors to exons D and E of the 6.5 kb androgen responsive region present as stably integrated templates. We will determine whether the patterns of receptor and nuclear factor binding differ in response to androgen (and glucocorticoids) in cells in which the androgen responsive region is active versus inactive. We will identify and characterize the non-receptor factor(s) that binds differentially and determine the role of this factor(s) in cell- and androgen-specific AR mRNA up-regulation. The long term goal of these studies is to provide a comprehensive physical and functional characterization of R mRNA autoregulatory mechanisms and to relate these mechanisms to hormonal responsiveness in normal and neoplastic cells.