MOLECULAR BIOLOGY OF STEROID HORMONE ACTION

几乎所有的哺乳动物细胞都含有一种或多种 类固醇激素的种类。 这些高亲和力受体蛋白 最有可能介导类固醇对细胞功能的主要影响 通过与靶中（或附近）的特定DNA序列相互作用 基因. 在这样做时，类固醇受体复合物刺激 启动转录，从而导致产量增加 特定的RNA。 复杂调节机制的研究 在高等真核生物中， 操纵这些生物的基因， 哺乳动物基因组 因此，我们转向简化 组织培养系统和分离的基因，以研究分子 类固醇激素调节基因表达的机制。 我们将使用遗传、生物化学和分子方法， 调查以下问题：1） 糖皮质激素受体和蛋白质的哪些部分是 它的激素结合，DNA结合和转录所需的， 刺激活动？ 2)它的生化成分是什么 类固醇调节转录所需的基因吗 3)哪些因素 确定一个基因是否是或不是类固醇反应在一个给定的 细胞（组织）类型？ 4)类固醇激素如何改变 基因表达的发育模式在一个明确的 区分系统？ 我们将重点关注小鼠糖皮质激素的研究 受体和两个特定的基因， 糖皮质激素;一个是大鼠基因编码的肝脏蛋白 第二个是编码α-1酸性糖蛋白的小鼠基因， 一种发育调节的细胞色素P450 我们的目的是 最终以详细的分子术语描述了 糖皮质激素受体与 细胞的转录机制。 我们的方法 不仅有助于阐明 类固醇激素的作用机制，但可能提供额外的 深入了解组织特异性基因表达的基础， 细胞分化的过程。

Virtually all mammalian cells contain receptors for one or more classes of steroid hormones. These high-affinity receptor proteins most likely mediate the major effects of steroids on cell function by interacting with specific DNA sequences in (or near) target genes. Upon so doing, the steroid-receptor complex stimulates initiation of transcription thereby leading to increased production of specific RNAs. The study of complex regulatory mechanisms in higher eukaryotes has been hampered by the difficulty in manipulating such organisms genetically and by the enormity of mammalian genomes. We therefore have turned to simplified tissue culture systems and isolated genes to study the molecular mechanisms by which steroid hormones regulate gene expression. We will use genetic biochemical and molecular approaches to investigate the following issues: 1) What is the structure of the glucocorticoid receptor and which portions of the protein are required for its hormone binding, DNA binding, and transcription stimulating activities? 2) What are the biochemical components required for steroid-regulated transcription? 3) What factors determine whether a gene is or is not steroid responsive in a given cell (tissue) type? 4) How do steroid hormones alter the developmental pattern of gene expression in a well defined differentiating system? We will focus our attention on studies of the mouse glucocorticoid receptor and two specific genes that are regulated by glucocorticoids; one is the rat gene encoding the liver protein alpha-1 acid glycoprotein and the second is a mouse gene encoding a developmentally regulated cytochrome P450. It is our intent to eventually describe in detailed molecular terms the nature of the interactions between the glucocorticoid receptor and the transcriptional machinery of the cell. The approaches we are taking should help not only in elucidating the molecular mechanisms of steroid hormone action but may provide additional insights into the basis for tissue-specific gene expression and the process of cell differentiation.