Department of Internal Medicine, Graduate School of Medical Science, Kanazawa University.
Department of Hygiene, Kanazawa University School of Medicine.
J Hypertens. 2021 May 1;39(5):1018-1024. doi: 10.1097/HJH.0000000000002742.
Aldosterone synthase gene, CYP11B2 is regulated by potassium and angiotensin II (Ang II). We have reported that Ang II could change the DNA methylation status around transcription factor-binding sites and a transcription start site (TSS) and activate expression of CYP11B2. Similar to Ang II, small increases in extracellular potassium levels also increase CYP11B2 mRNA levels.
Adrenocortical H295R cells were treated with different doses of potassium. Methylation analysis of CYP11B2 promoter region was done by bisulfite sequencing. CYP11B2 mRNA and protein levels, chromatin accessibility, methylation and demethylation activity were estimated. The transcriptional ability of CYP11B2 promoter with or without methylation was assessed. Potassium stimulation caused DNA demethylation around cyclic AMP responsive element binding protein 1 (CREB1) and nuclear receptor subfamily 4 group A (NR4A) family-binding sites and a TSS; demethylation was accompanied by recruitment of CREB1 and NR4A1 and increased chromatin accessibility of the CYP11B2 promoter. DNA methylation activity decreased in the nucleus. DNA demethylation at CpG1 (Ad1), CpG2 (Ad5) and CpG3 were detected within 2 to 4 days after potassium (16 mmol/l) stimulation. The changes reached a maximum level by day 7. DNA at CpG2 (Ad5) and CpG3 was re-methylated to levels that were similar to those of nontreated cells at day 9. Potassium treatment significantly reduced DNA methylation activity at days 7 and 9. DNA demethylation activity was not changed by potassium.
: Potassium induced reversibly DNA demethylation, which switches the phenotype of CYP11B2 expression from an inactive to an active state.
醛固酮合酶基因 CYP11B2 受钾和血管紧张素 II（Ang II）的调节。我们已经报道过 Ang II 可以改变转录因子结合位点和转录起始位点（TSS）周围的 DNA 甲基化状态，从而激活 CYP11B2 的表达。类似于 Ang II，细胞外钾水平的微小升高也会增加 CYP11B2 mRNA 水平。
用不同剂量的钾处理肾上腺皮质 H295R 细胞。通过亚硫酸氢盐测序法对 CYP11B2 启动子区域进行甲基化分析。估计 CYP11B2 mRNA 和蛋白水平、染色质可及性、甲基化和去甲基化活性。评估了具有或不具有甲基化的 CYP11B2 启动子的转录能力。钾刺激导致环磷酸腺苷反应元件结合蛋白 1（CREB1）和核受体亚家族 4 组 A（NR4A）家族结合位点和 TSS 周围的 DNA 去甲基化；去甲基化伴随着 CREB1 和 NR4A1 的募集以及 CYP11B2 启动子的染色质可及性增加。核内的 DNA 甲基化活性降低。在钾（16mmol/l）刺激后 2 至 4 天内检测到 CpG1（Ad1）、CpG2（Ad5）和 CpG3 处的 DNA 去甲基化。这些变化在第 7 天达到最大值。第 9 天，CpG2（Ad5）和 CpG3 处的 DNA 被重新甲基化，达到与未处理细胞相似的水平。钾处理显著降低了第 7 天和第 9 天的 DNA 甲基化活性。钾处理没有改变 DNA 去甲基化活性。
钾诱导可逆的 DNA 去甲基化，将 CYP11B2 表达的表型从非活性状态切换为活性状态。
