REGULATION OF REPRODUCTION

该项目的长期目标是彻底了解 类固醇激素在哺乳动物生殖中的作用。要开始这些 我们将使用实验室啮齿动物和啮齿动物细胞系统进行研究 来自生殖组织。一般而言，生殖组织和其他组织 (卵巢、睾丸、胎盘、肾上腺)长期调节类固醇激素 通过调节编码酶的mRNAs的丰度来合成 合成类固醇的物质。目前还不清楚这是如何发生的； 这些mRNAs的丰度可能在转录和 转录后。此外，尽管同样的一小部分 酶介导不同组织中类固醇的合成，编码基因 这些酶在不同的组织中受到不同的调节，并且 不同的哺乳动物在同一组织中的情况有所不同。我们的工作将 最初关注P450c 17。这一种酶有两种截然不同的 活性，17α羟基酶和17，20裂解酶，但仅由 只有一个基因。在没有任何P45OCl7活性的情况下，矿物皮质激素是 合成的。在仅存在羟基酶活性的情况下， 糖皮质激素是合成的，在两种羟基酶存在的情况下 裂解酶活力、性类固醇的合成。因此，P45Ocl7是一种 是合成所有类固醇激素的关键分支。我们只是 开始了解某些类固醇激素生成的基因上的信号 酶在某些因素的调节中是必需的，但我们知之甚少。 关于组织特异性所需的调控序列或因子 对这些基因的调控。类固醇合成的生理调节 在老鼠身上有很好的特征。我们已经克隆了大鼠P45OCl7 现在希望克隆大鼠P450c 17基因并对其进行研究。 监管。通过稳定地将其导入培养的肾上腺和间质 细胞系，我们可以研究这种基因是如何在组织特异性的 方式由影响转录和 转录后事件。此外，通过瞬时转染 肾上腺、间质和非内分泌成纤维细胞系，推测 大鼠P450c 17基因的调控序列，我们可以确定这是如何 基因受刺激/抑制因子和组织特异性因子的调控。 我们将鉴定荷尔蒙所需的DNA序列 该基因的刺激/抑制和组织特异性表达，以及 将开始对这一过程所需的核蛋白进行表征 监管。成功完成这些研究将给我们带来更好的 了解肾上腺和睾丸是如何使用相同的基因， 合成不同种类的类固醇激素。

The long term objective of this project is a thorough understanding of the roles of steroid hormones in mammalian reproduction. To begin these studies we will use laboratory rodents and rodent cell systems derived from reproductive tissues. In general, reproductive and other tissues (ovary, testis, placenta, adrenal) chronically regulate steroid hormone synthesis by regulating the abundance of the mRNAs encoding the enzymes that synthesize steroids. It is still unclear how this occurs; the abundances of these mRNAs may be regulated both transcriptionally and post-transcriptionally. Furthermore, although the same small set of enzymes mediate steroidogenesis in different tissues, the genes encoding these enzymes are regulated differently in different tissues, and differently in the same tissue among different mammals. Our work will focus initially on P450c 17. This one enzyme has two distinct activities, 17alpha hydroxylase and 17,20 lyase, but is encoded by only one gene. In the absence of any P45Ocl7 activity, mineralocorticoids are synthesized. In the presence of only the hydroxylase activity, glucocorticoids are synthesized, and in the presence of both hydroxylase and lyase activities, sex steroids are synthesized. P45Ocl7 thus is a key branch in the synthesis of all steroid hormones. We are just beginning to understand what signals on the genes for some steroidogenic enzymes are necessary for regulation by some factors, but little is known about the regulatory sequences or factors necessary for tissue-specific regulation of these genes. The physiologic regulation of steroidogenesis in the rat is well characterized. We have already cloned rat P45Ocl7 cDNA, and now wish to clone the rat P450c 17 gene and study its regulation. By stably transfecting it into cultured adrenal and Leydig cell lines, we can study how this gene is regulated in a tissue-specific manner by factors influencing both transcriptional and post-transcriptional events. In addition, by transiently transfecting adrenal, Leydig and non-endocrine fibroblast cell lines, with putative regulatory sequences of the rat P450c 17 gene, we can determine how this gene is regulated by stimulatory/repressive- and tissue-specific factors. We will identify the DNA sequences necessary for hormonal stimulation/repression and tissue-specific expression of this gene, and will begin to characterize the nuclear proteins necessary for this regulation. Successful completion of these studies will give us a better understanding of how adrenals and testes, using the same genes, synthesize different classes of steroid hormones.