Dell G C, Morley S D, Mullins J J, Williams B C, Walker S W
Department of Clinical Biochemistry, University of Edinburgh, U.K.
Endocr Res. 1996 Nov;22(4):363-8. doi: 10.1080/07435809609043719.
Regulation of AT1 receptor mRNA expression is an important determinant of angiotensin II-induced steroidogenesis. We have PCR-amplified the bovine adrenal AT1 receptor coding region using primers designed from the published bovine AT1 receptor sequence. This has been used as a probe on Northern blots to detect changes in the levels of AT1 receptor mRNA in primary cultures of bovine zona fasciculata cells in response to activation of several different signal transduction mechanisms in addition to two major adrenal steroid products, cortisol and aldosterone. AT1 receptor mRNA decreased in response to 6hr AII (10 nM) treatment, but returned to basal levels following 48h AII treatment. This effect was mimicked by the phorbol ester PMA (1 microM) and the calcium ionophore A23187 (1 microM), both singly and in combination. Activation of the cAMP pathway by ACTH (1 nM) and 8-bromo-cAMP (0.1 microM) also decreased AT1 receptor mRNA levels. In contrast, both IGF-1 (10 ng/ml) and potassium ions (12 mM) increased the levels of AT1 receptor mRNA. Finally, cortisol (10 microM) but not aldosterone (100 nM) decreased AT1 receptor mRNA. We conclude that the regulation of AT1 receptor mRNA in bovine zona fasciculata cells could involve several different signal transduction systems in addition to adrenocortical steroids themselves.
AT1受体mRNA表达的调控是血管紧张素II诱导类固醇生成的重要决定因素。我们使用根据已发表的牛AT1受体序列设计的引物，通过PCR扩增了牛肾上腺AT1受体编码区。这已被用作Northern印迹的探针，以检测牛束状带细胞原代培养物中AT1受体mRNA水平的变化，这些变化是对几种不同信号转导机制激活的响应，此外还涉及两种主要的肾上腺类固醇产物皮质醇和醛固酮。AT1受体mRNA在6小时血管紧张素II（10 nM）处理后下降，但在48小时血管紧张素II处理后恢复到基础水平。佛波酯PMA（1 microM）和钙离子载体A23187（1 microM）单独或联合使用均可模拟这种效应。促肾上腺皮质激素（1 nM）和8-溴环磷腺苷（0.1 microM）激活cAMP途径也会降低AT1受体mRNA水平。相比之下，胰岛素样生长因子-1（10 ng/ml）和钾离子（12 mM）均可增加AT1受体mRNA水平。最后，皮质醇（10 microM）可降低AT1受体mRNA水平，而醛固酮（100 nM）则无此作用。我们得出结论，除肾上腺皮质类固醇本身外，牛束状带细胞中AT1受体mRNA的调控可能涉及几种不同的信号转导系统。
