MOLECULAR MECHANISMS OF GLUCOCORTICOID HORMONE ACTION

了解基因表达的调节机制是 对于理解发展和分化是必不可少的，因此， 当这些过程出错时，可能会出现癌症和其他疾病。 对类固醇激素依赖调节的详细认识 机制可能导致现有治疗方案的改进和 发展新的干预途径，特别是在 内分泌依赖型肿瘤。我们的长期目标是了解这些 类固醇控制靶基因表达的机制。 过去的研究主要集中在类固醇的相互作用上。 带有DNA的受体。在这一框架内，新的战略和 应用程序将解决三个具体问题。 一、糖皮质激素和孕激素受体是如何区分的 诱导靶基因？DNA结合之间有一些不同 糖皮质激素、孕激素、盐皮质激素和雄激素结构域 感受器。我们的研究表明糖皮质激素和黄体酮 受体识别目标DNA序列相似，如果不相同的话。 这就提出了这样一个问题：对这两种激素的反应是否 严格受受体表达部位的控制，还是更多 微妙的因素也起到了重要作用。建议进行的实验 这一部分详细阐述了所提出的基本生物学难题 上面。 受体在体内对靶分子的占位情况 与荷尔蒙反应有关吗？我们提出了一种新的，逆转录病毒 用向量法评估受体的相对占有率 它在体内的靶点作为生物活性的函数 激素反应元件。荷尔蒙反应的幅度将是 通过修改启动子来改变。上下文，目标的顺序 或通过刺激其他细胞信号转导途径。 类固醇依赖改变在刺激脑血管疾病中的其他方面 其他细胞信号转导途径。类固醇的其他方面- 染色质结构和转录起始的依赖性变化 还将评估复杂的加载。 糖皮质激素受体是如何在脑组织中发现靶成分的 基因组？隐藏在哺乳动物基因组中的是少数几个靶标 基因。受体通过以下方式进行靶点搜索的模型 扩散或沿DNA滑动并不能令人满意地解释 核内DNA的数量和密度带来的困难 环境。我们认为糖皮质激素受体可以搜索DNA 通过域间转移。类似于人猿泰山在藤蔓之间摇摆，这 机制设想受体在DNA位点之间转移而不需要 脱离DNA。分子、动力学和物理的结合 将采用各种方法来测试这一建议。

Understanding the mechanisms of regulation of gene expression is essential to comprehension of development and differentiation, and thus, cancer and other disorders that may arise when these processes go awry. A detailed understanding of steroid hormone-dependent regulatory mechanisms may lead to improvement of existing therapeutic regimens and the development of novel avenues for intervention, particularly in endocrine-dependent neoplasia. Our long term goal is to understand these mechanisms through which steroids control expression of target genes. Past research efforts have focused on the interaction of steroid receptors with DNA. Within this framework, new strategies and applications will address three specific questions. I. How do glucocorticoid and progesterone receptors differentially induce target genes? There are a few differences among the DNA binding domains of glucocorticoid, progesterone, mineralocorticoid, and androgen receptors. Our studies imply that glucocorticoid and progesterone receptors recognize target DNA sequence similarly, if not identically. This raises the question of whether response to these two hormones is controlled strictly by the site of receptor expression or whether more subtle factor also significantly contribute. Experiments proposed in this section address in detail the fundamental biological conundrum posed above. II. How well does receptor occupancy of target elements in vivo correlate with hormone responsiveness? We propose a novel, retroviral vector approach to assess the relative extent of receptor occupancy of its target site in vivo as a function of the biological activity of the hormone response element. The magnitude of hormone response will be altered by modifying the promoter. context, the sequence of the target site, or by stimulation of other cell signal transduction pathways. Additional aspects of steroid-dependent alterations in stimulation of other cell signal transduction pathways. Additional aspects of steroid- dependent alterations in chromatin structure and transcription initiation complex loading will also be assessed. III. How does the glucocorticoid receptor find target elements in the genome? Buried within the mammalian genome are a handful of target genes. Models in which receptor conducts a search for targets sites by diffusion or by sliding along the DNA do not satisfactorily account for the difficulties posed by the amount and density of DNA in the nuclear environment. We propose that the glucocorticoid receptor can search DNA by interdomain transfer. Analogous to Tarzan swinging vine-to-vine, this mechanism envisions receptors transferring between DNA sites without ever dissociating from DNA. A combination of molecular, kinetic and physical approaches will be employed to test this proposal.