MOLECULAR BIOLOGY OF HORMONE REGULATED CYTOLYSIS

观察到的对激素处理的生理反应是 组织特异性基因网络的协调调节。 的 类固醇激素的作用是由细胞内 受体蛋白 激素受体复合体紧密地 与细胞核相关，并对特定的 DNA序列发现内和附近的免疫反应基因。 糖皮质激素受体（GR）已被广泛应用于 在生化和遗传水平上的特点;这种分析 最近分离的GR编码促进了 序列的 GR在DNA上的作用位点也被 详细检查; GR在体外特异性结合相同的 在体内作为一种可诱导的蛋白的序列， 转录增强子 细胞特异性激素的一个例子 反应是GR依赖性诱导的细胞溶解在两个小鼠 胸腺瘤细胞系（WEHI 7）和S49）。 的分子基础 在这些细胞中观察到的细胞死亡是未知的，但最有可能是 在转录水平上由GR调节。 糖皮质激素可用于治疗几种人类疾病 淋巴癌，有人认为， WEHI 7和S49细胞的细胞死亡可能是一个很好的模型系统， 研究类固醇治疗的临床反应，如肿瘤 白血病细胞的消退和细胞溶解。 我们建议使用几种分子生物学方法， 确定酶调节细胞溶解的机制。 一是 将确定细胞溶解所需的GR活性， 分离和表征GR编码序列（cDNA和 基因组）从一类独特的类固醇抗性突变体， 表达一种结合激素和DNA的GR形式， 在调节转录的能力上明显有缺陷。 第二，我们将分离裂解所需的基因， 消减cDNA克隆技术和逆转录病毒介导的 转座子标记 本研究的长期目标是 描绘组织特异性糖皮质激素基因网络， 分子遗传学和了解GR依赖基因 表达是协调和发育调节的。

The observed physiological response to hormone treatment is the coordinate regulation of tissue-specific gene networks. The effects of steroid hormones are mediated by intracellular receptor proteins. Hormone receptor complexes are tightly associated with the nucleus and have high affinities for specific DNA sequences found within and near hormone-responsive genes. Glucocorticoid receptors (GR) have been extensively characterized at the biochemical and genetic level; this analysis has been facilitated by the recent isolation of GR coding sequences. The site of GR action on the DNA has also been examined in detail; the GR binds specifically in vitro to the same sequence which acts in vivo as a hormone-inducible transcriptional enhancer. One example of a cell specific hormone response is the GR-dependent induction of cytolysis in two murine thymoma cell lines (WEHI7) and S49). The molecular basis for the observed cell death in these cells is not known, but is most likely regulated at the level of transcription by the GR. Since glucocorticoids are useful in the treatment of several human lymphatic cancers, it has been suggested that the hormoneinduced cell death of WEHI7 and S49 cells may be a good model system for the study of clinical responses to steroid therapy, such as tumor regression and cytolysis of leukemic cells. We propose to use several molecular biological approaches to identify the mechanism of hormone-regulated cytolysis. First, we will determine what GR activities are required for cytolysis by isolating and characterizing GR coding sequences (cDNA and genomic) from a unique class of steroid resistant mutants which express a form of the GR that binds hormone and DNA, but is apparently defective in its ability to modulate transcription. Second, we will isolate genes required for lysis using the techniques of subtraction cDNA cloning and retrovirus-mediated transposon tagging. The long term goal of this study is to delineate tissue-specific glucocorticoid gene networks using molecular genetics and to understand how GR-dependent gene expression is coordinately and developmentally regulated.