Schmitt-Ney M, Doppler W, Ball R K, Groner B
Friedrich Miescher Institute, Basel, Switzerland.
Mol Cell Biol. 1991 Jul;11(7):3745-55. doi: 10.1128/mcb.11.7.3745-3755.1991.
Transcription from the beta-casein milk protein gene promoter is induced by the synergistic action of glucocorticoid and prolactin hormones in the murine mammary epithelial cell line, HC11. We analyzed the binding of nuclear proteins to the promoter and determined their binding sites. Site-directed mutagenesis was used to determine the function of nuclear factor binding. During lactogenic hormone induction of HC11 cells, the binding of two nuclear factors increased. The binding of two other nuclear factors, present in uninduced cells, decreased. The basal activity of the promoter could be increased to and above the level of the induced wild-type promoter when the recognition sequences of the negatively regulated factors were mutated. This suggests that the beta-casein promoter is regulated by the relief of the repression of transcription. An essential tissue-specific factor was also found in nuclear extracts from the mammary glands of mice. Mutation of its recognition sequence in the beta-casein promoter led to the abolition of the induction of transcription by lactogenic hormones. The DNA sequences recognized by all five of these nuclear factors are conserved in the promoters of different casein genes from several species, confirming their importance in the regulation of milk protein gene transcription.
在小鼠乳腺上皮细胞系HC11中，β-酪蛋白乳蛋白基因启动子的转录是由糖皮质激素和催乳素的协同作用诱导的。我们分析了核蛋白与启动子的结合，并确定了它们的结合位点。使用定点诱变来确定核因子结合的功能。在HC11细胞的产乳激素诱导过程中，两种核因子的结合增加。未诱导细胞中存在的另外两种核因子的结合减少。当负调控因子的识别序列发生突变时，启动子的基础活性可以增加到诱导的野生型启动子的水平及以上。这表明β-酪蛋白启动子是通过解除转录抑制来调控的。在小鼠乳腺的核提取物中也发现了一种必需的组织特异性因子。其在β-酪蛋白启动子中的识别序列发生突变导致产乳激素诱导的转录消失。这五种核因子识别的DNA序列在来自几个物种的不同酪蛋白基因的启动子中是保守的，证实了它们在乳蛋白基因转录调控中的重要性。
