Bristol Medical School: Translational Health Sciences, University of Bristol, Bristol, United Kingdom.
Endocrinology. 2019 Mar 1;160(3):587-604. doi: 10.1210/en.2018-00840.
We tested the hypothesis that mouse ATC1 and ATC7 cells, the first adrenocortical cell lines to exhibit a complete zona fasciculata (ZF) cell phenotype, respond to dynamic ACTH stimulation in a similar manner as the adrenal gland in vivo. Exploiting our previous in vivo observations that gene transcription within the steroidogenic pathway is dynamically regulated in response to a pulse of ACTH, we exposed ATC1 and ATC7 cells to various patterns of ACTH, including pulsatile and constant, and measured the transcriptional activation of this pathway. We show that pulses of ACTH administered to ATC7 cells can reliably stimulate a pulsatile pattern of transcriptional activity that is comparable to that observed in adrenal ZF cells in vivo. Hourly pulses of ACTH stimulate dynamic increases in CREB phosphorylation (pCREB) and transcription of genes involved in critical steps of steroidogenesis including signal transduction (e.g., MRAP), cholesterol delivery (e.g., StAR), and steroid biosynthesis (e.g., CYP11A1), as well as those relating to transcriptional regulation of steroidogenic factors (e.g., SF-1 and Nur-77). In contrast, constant ACTH stimulation results in a prolonged and exaggerated pCREB and steroidogenic gene transcriptional response. We also show that when a large dose of ACTH (100 nM) is applied after these treatment regimens, a significant increase in steroidogenic transcriptional responsiveness is achieved only in cells that have been exposed to pulsatile, rather than constant, ACTH. Our data support our in vivo observations that pulsatile ACTH is important for the optimal transcriptional responsiveness of the adrenal. Importantly, our data suggest that ATC7 cells respond to dynamic ACTH stimulation.
我们验证了这样一个假设，即具有完整束状带细胞表型的首个人类肾上腺皮质细胞株 ATC1 和 ATC7 对促肾上腺皮质激素（ACTH）的刺激表现出与体内肾上腺相似的动态反应。我们利用之前在体内观察到的类固醇生成途径中的基因转录会对 ACTH 脉冲做出动态调节的发现，使 ATC1 和 ATC7 细胞暴露于各种 ACTH 模式下，包括脉冲式和持续式，并测量该途径的转录激活。结果显示，给予 ATC7 细胞的 ACTH 脉冲可可靠地刺激与体内肾上腺束状带细胞中观察到的相似的脉冲式转录活性模式。每隔一小时给予 ACTH 脉冲可刺激 CREB 磷酸化（pCREB）和参与类固醇生成关键步骤的基因转录的动态增加，包括信号转导（例如，MRAP）、胆固醇转运（例如，StAR）和类固醇生物合成（例如，CYP11A1），以及与类固醇生成因子的转录调节相关的基因（例如，SF-1 和 Nur-77）。相比之下，持续的 ACTH 刺激会导致 pCREB 和类固醇生成基因转录反应的延长和过度。我们还表明，当在这些治疗方案后应用大剂量的 ACTH（100 nM）时，仅在已经暴露于脉冲式而不是持续式 ACTH 的细胞中才能实现类固醇生成转录反应性的显著增加。我们的数据支持我们的体内观察结果，即脉冲式 ACTH 对于肾上腺的最佳转录反应性是重要的。重要的是，我们的数据表明 ATC7 细胞对动态 ACTH 刺激有反应。
