McAllister J M, Hornsby P J
Department of Medicine, University of California, San Diego, La Jolla 92093.
Endocrinology. 1988 May;122(5):2012-8. doi: 10.1210/endo-122-5-2012.
The relationship between cAMP and protein kinase C in the regulation of 3 beta-hydroxysteroid dehydrogenase (3 beta HSD), 17 alpha-hydroxylase, and sulfotransferase was examined in human fetal adrenocortical cells under defined serum-free conditions in culture. Forskolin induced 3 beta HSD and 17 alpha-hydroxylase in a dose-dependent manner, with maximal effects at 10 microM. 12-O-Tetradecanoyl phorbol 13-acetate (TPA) at 1 nM depressed the induction of 17 alpha-hydroxylase activity by forskolin by more than 95% and increased the stimulation of 3 beta HSD activity by forskolin by 4- to 5-fold. Increases were maximal at 48-72 h of incubation. Dehydroepiandrosterone sulfotransferase activity increased over 48 h when cells were transferred to serum-free defined medium. Addition of 10 microM forskolin stimulated sulfotransferase activity only when cells remained in 10% serum. TPA at 1 nM inhibited the increase in sulfotransferase activity. The concentration of TPA required for inhibition of forskolin-stimulated 17 alpha-hydroxylase and sulfotransferase activity was similar to that required for enhancement of forskolin-induced 3 beta HSD activity, suggesting that comparable levels of C kinase activation are involved in these events. Angiotensin II, carbachol, epidermal growth factor, and fibroblast growth factor had actions similar to those of TPA on one or more of these enzyme activities. TPA also had similar actions on enzyme activities when they were stimulated by cAMP analogs rather than by forskolin. These studies suggest that adrenal steroid biosynthesis is under dual regulation by cAMP and protein kinase C. cAMP induces enzymes required for synthesis of 17 alpha-hydroxylated steroids, including the adrenal androgens. Activation of protein kinase C may play a complementary role by enhancing the induction of enzymes required for non-17 alpha-hydroxylated steroid biosynthesis and inhibiting those involved in the synthesis of androgens.
在无血清培养的特定条件下，研究了人胎儿肾上腺皮质细胞中cAMP与蛋白激酶C在调节3β-羟基类固醇脱氢酶（3βHSD）、17α-羟化酶和磺基转移酶方面的关系。福斯高林以剂量依赖的方式诱导3βHSD和17α-羟化酶，在10μM时达到最大效应。1 nM的12-O-十四烷酰佛波醇13-乙酸酯（TPA）使福斯高林对17α-羟化酶活性的诱导降低超过95%，并使福斯高林对3βHSD活性的刺激增加4至5倍。在孵育48至72小时时增加最大。当细胞转移至无血清的特定培养基中时，脱氢表雄酮磺基转移酶活性在48小时内增加。仅当细胞保留在10%血清中时，添加10μM福斯高林才刺激磺基转移酶活性。1 nM的TPA抑制磺基转移酶活性的增加。抑制福斯高林刺激的17α-羟化酶和磺基转移酶活性所需的TPA浓度与增强福斯高林诱导的3βHSD活性所需的浓度相似，表明这些事件涉及相当水平的C激酶激活。血管紧张素II、卡巴胆碱、表皮生长因子和成纤维细胞生长因子对这些酶活性中的一种或多种具有与TPA相似的作用。当酶活性由cAMP类似物而非福斯高林刺激时，TPA对酶活性也有类似作用。这些研究表明，肾上腺类固醇生物合成受cAMP和蛋白激酶C的双重调节。cAMP诱导合成17α-羟化类固醇所需的酶，包括肾上腺雄激素。蛋白激酶C的激活可能通过增强非17α-羟化类固醇生物合成所需酶的诱导并抑制参与雄激素合成的酶来发挥互补作用。
