Charron J, Drouin J
Proc Natl Acad Sci U S A. 1986 Dec;83(23):8903-7. doi: 10.1073/pnas.83.23.8903.
Glucocorticoid hormones alter transcription of specific genes. Glucocorticoid-stimulated genes have been especially useful in unraveling molecular events responsible for positive gene regulation in mammals. The gene encoding proopiomelanocortin (POMC), which is under feedback inhibition by glucocorticoids, provides a model system to study negative gene regulation. Using an episomal bovine papilloma virus vector, we now demonstrate that a 769-base-pair fragment containing the rat POMC promoter is sufficient to confer glucocorticoid inhibition. Transcription from the episomal POMC promoter starts at the same site and is inhibited by glucocorticoids to the same extent as POMC transcription in the anterior pituitary. Glucocorticoid inhibition is specific for POMC transcripts; neither bovine papilloma virus nor cellular actin mRNAs are affected by glucocorticoids. Thus, the episomal bovine papilloma virus/POMC system can be used to study the relationship between negative regulation of POMC transcription and chromatin structure.
糖皮质激素可改变特定基因的转录。糖皮质激素刺激的基因在揭示哺乳动物中负责正性基因调控的分子事件方面特别有用。编码阿黑皮素原（POMC）的基因受到糖皮质激素的反馈抑制，它提供了一个研究负性基因调控的模型系统。利用一种游离型牛乳头瘤病毒载体，我们现在证明，一个包含大鼠POMC启动子的769个碱基对的片段足以赋予糖皮质激素抑制作用。游离型POMC启动子的转录起始于相同位点，并受到糖皮质激素的抑制，其程度与垂体前叶中POMC的转录相同。糖皮质激素抑制作用对POMC转录本具有特异性；糖皮质激素既不影响牛乳头瘤病毒，也不影响细胞肌动蛋白mRNA。因此，游离型牛乳头瘤病毒/POMC系统可用于研究POMC转录的负性调控与染色质结构之间的关系。
