ACTH INDUCTION OF CYTOCHROME P450 IN ADRENAL CELLS

ACTH的慢性作用维持最佳的类固醇生成能力， 肾上腺皮质，保证肾上腺类固醇激素的产生 （皮质醇、皮质酮和醛固酮）。 这个过程是 通过cAMP介导，对基因编码施加转录压力， 肾上腺皮质类固醇羟化酶（P450）和相关蛋白。 这 竞争性更新提出，以确定如何四个同源结构域蛋白 与牛CYP 17的主要cAMP反应序列（CRS 1）结合 （P450 c17）相互作用， 机械. 使用体外转录/翻译，EMSA，细胞 转染、体外转录和诱变;二聚化和 将鉴定这些同源域蛋白中的反式激活结构域 沿着与它们相互作用的共活化剂和/或TAF。 肾上腺氧还蛋白支持肾上腺中线粒体P450的活性 皮质和大多数其他组织。 编码这种2Fe-2S蛋白的基因 也受ACTH（cAMP）和新蛋白质的转录调控 与该CRS的结合将以与CYP 17相同的方式进行表征 CRS 1结合蛋白。 这将允许比较cAMP依赖性 主要表达于细胞中的基因的转录调控 类固醇生成细胞（CYP 17），其中一个在类固醇生成和 非类固醇生成细胞 运动所需的信号通路 促肾上腺皮质激素的类固醇基因的转录压力是cAMP- 放线菌酮（CHX）的反应和抑制。 cAMP反应性/ CHX敏感基因座将被确定为理解这一点的手段。 信号通路 拟议的研究将建立第一个 时间在生化水平如何肽激素从前 垂体控制类固醇生成酶的水平， 详细了解这一过程所需的信号通路。 这些事件是类固醇激素生物合成所必需的 导致生殖能力和代谢平衡。

The chronic action of ACTH maintains optimal steroidogenic capacity in the adrenal cortex, assuring production of adrenal steroid hormones (cortisol, corticosterone and aldosterone) on demand. This process is mediated by cAMP exerting transcriptional pressure on genes encoding adrenocortical steroid hydroxylases (P450s) and related proteins. This competitive renewal proposes to determine how four homeodomain proteins binding to the predominant cAMP response sequence (CRS1) of bovine CYP17 (P450c17) interact with one another and the basal transcription machinery. Using in vitro transcription/translation, EMSA, cell transfection, in vitro transcription and mutagenesis; dimerization and transactivation domains in these homeodomain proteins will be identified along with coactivators and/or TAFs with which they interact. Adrenodoxin supports activity of mitochondrial P450s in the adrenal cortex and most other tissues. The gene encoding this 2Fe-2S protein is also regulated transcriptionally by ACTH(cAMP) and the novel protein binding to this CRS will be characterized in the same manner as CYP17 CRS1 binding proteins. This will permit comparison of cAMP-dependent transcriptional regulation of a gene predominantly expressed in steroidogenic cells (CYP17) with one expressed in both steroidogenic and nonsteroidogenic cells. The signalling pathway required for exertion of transcriptional pressure by ACTH of steroidogenic genes is cAMP- responsive and inhibited by cycloheximide (CHX). The cAMP-responsive/ CHX-sensitive locus will be identified as a means of understanding this signalling pathway. The proposed studies will establish for the first time at the biochemical level how peptide hormones from the anterior pituitary control levels of steroidogenic enzymes as well as providing detailed insight into the signalling pathway required for this process. These events are required for the biosynthesis of steroid hormones leading to reproductive capacity and metabolic homeostasis.