CHARACTERIZATION AND FUNCTION OF STEROID REGULATED GENES IN MANDUCA

许多细胞功能受基因组表达变化的调节。 一 调节这些变化的主要化合物是激素， 通过类固醇/甲状腺受体超家族的成员。 这些激素 受体通过与DNA的特定区域结合来改变基因表达， 调节相邻基因的转录。 这些区域的性质 DNA和受调控基因的功能对于 了解正常的生理功能，发育和 疾病 非哺乳动物模型系统对于理解 这些激素在所有生物体中基因调控的基本机制。 许多研究人员的研究表明， 昆虫如黑腹果蝇（Drosophilamelanogaster）和烟草天蛾（Manducasexta）用于这种模型 系统. 类固醇水平的上升和下降都可以作为信号， 通过增加特定的转录来改变细胞功能 基因. 到目前为止，这两种机制之间的差异是， 不清楚 这个项目将使用昆虫Manducasexta作为模型 系统来表征神经系统中的基因，其转录是 随着类固醇激素水平的下降， 蜕皮激素 昆虫蜕皮激素受体及其特异性DNA结合 位点与脊椎动物类固醇受体具有高度同源性， 因此，调节机制可能是保守的。 我们已经从烟草天蛾的神经系统中分离出几个基因 其转录物随着类固醇水平的下降而大量增加。 的 表达这些基因之一的特定类固醇需求将是 结合体内和体外操作进行研究， 蜕皮激素水平 这个基因的转录率将被确定 在发育过程中，以测试调控是否在转录水平， 水平 蛋白质合成抑制剂对细胞水平的影响 成绩单将被确定，参与下降的因素 将研究转录水平。 关于调控区域的研究 基因和潜在的调节蛋白的存在将是 启动。 这个项目的一个长期目标是确定这些基因的功能 在神经系统的发展中。 发展性分析 这种类型的其他基因的空间表达模式将被 完成，以关联已知的生理变化发生在 神经系统与特定的转录本的存在。

Many cellular functions are regulated by change in genome expression. One major class of compounds which mediate these changes are hormones acting via members of the steroid/thyroid receptor superfamily. These hormone receptors alter gene expression by binding to specific regions of DNA and regulating transcription of adjacent genes. The nature of these regions of DNA and the functions of the genes regulated are of central importance to the understanding of normal physiological function, development and disease. Non-mammalian model systems have been invaluable in understanding the basic mechanisms of gene regulation by these hormones in all organisms. Studies by a number of investigators have shown the importance of using insects such as Drosophila melanogaster and Manduca sexta for such model systems. Both a rise in steroid levels and a decline can act as the signal which alters cellular function by an increase in the transcription of specific genes. The differences between the two mechanisms involved are, as yet, unclear. This project will use the insect, Manduca sexta, as a model system to characterize genes in the nervous system, whose transcription is increased by the declining levels of the steroid hormones, the ecdysteroids. Insect ecdysteroid receptors and their specific DNA binding sites have a high degree of homology with vertebrate steroid receptors, thus the mechanisms of regulation are likely to be conserved. We have isolated several genes from the nervous system of Manduca sexta whose transcripts increase in abundance as steroid levels decline. The specific steroid requirements for expression of one of these genes will be investigated with a combination of in vivo and in vitro manipulations of ecdysteroid levels. The transcription rate of this gene will be determined during development to test whether the regulation is at the transcriptional level. The effect of protein synthesis inhibitors on the levels of transcript will be determined and factors involved in the decline in transcript levels will be investigated. Studies on the regulatory regions of the gene and presence of potential regulatory proteins will be initiated. One long-term of this project is to determine the function of these genes in the development of the nervous system. An analysis of the developmental and spatial expression patterns of additional genes of this type will be completed to correlate the known physiological changes taking place in the nervous system with the presence of a particular transcript.