Perla Sravan, Kumar Ashok
Department of Pharmacology, Yale School of Medicine, New Haven, CT, USA.
Department of Pathology, New York Medical College, Valhalla, NY, USA.
bioRxiv. 2023 Nov 23:2023.11.22.568343. doi: 10.1101/2023.11.22.568343.
Hypertension is caused by a combination of genetic and environmental factors. Angiotensinogen (AGT) is a component of RAAS, that regulates blood pressure. The human angiotensinogen (hAGT) gene has -6A/-6G polymorphism and -6A variant is associated with human hypertension. In this study, we have investigated the epigenetic regulation of the hAGT. To understand transcriptional regulation of the hAGT, we have made transgenic animals containing -6A. We show that HS affects DNA methylation and modulates transcriptional regulation of this gene in liver and kidney. High salt (HS) increases hAGT gene expression in -6A TG mice. We have observed that the number of CpG sites in the hAGT promoter is decreased after HS treatment. In the liver, seven CpG sites are methylated whereas after HS treatment, only three CpG sites remain methylated. In the kidney, five CpG sites are methylated, whereas after HS treatment, only three CpG sites remain methylated. These results suggest that HS promotes DNA demethylation and increasing AGT gene expression. RT-PCR and immunoblot analysis show that hAGT gene expression is increased by HS. Chip assay has shown that transcription factors bind strongly after HS treatment. RNA-Seq identified differentially expressed genes, novel target genes associated with hypertension, top canonical pathways, upstream regulators. One of the plausible mechanisms for HS induced up-regulation of the hAGT gene is through IL-6/JAK/STAT3/AGT axis.
高血压是由遗传和环境因素共同引起的。血管紧张素原（AGT）是肾素-血管紧张素-醛固酮系统（RAAS）的一个组成部分，该系统调节血压。人类血管紧张素原（hAGT）基因存在-6A/-6G多态性，-6A变异体与人类高血压相关。在本研究中，我们研究了hAGT的表观遗传调控。为了解hAGT的转录调控，我们制备了含有-6A的转基因动物。我们发现高盐（HS）影响DNA甲基化，并调节该基因在肝脏和肾脏中的转录调控。高盐增加了-6A转基因小鼠中hAGT基因的表达。我们观察到，高盐处理后，hAGT启动子中的CpG位点数量减少。在肝脏中，七个CpG位点发生甲基化，而高盐处理后只剩下三个CpG位点甲基化。在肾脏中，五个CpG位点发生甲基化，而高盐处理后只剩下三个CpG位点甲基化。这些结果表明，高盐促进DNA去甲基化并增加AGT基因的表达。逆转录聚合酶链反应（RT-PCR）和免疫印迹分析表明，高盐可增加hAGT基因的表达。染色质免疫沉淀分析（Chip分析）表明，高盐处理后转录因子结合增强。RNA测序（RNA-Seq）鉴定了差异表达基因、与高血压相关的新靶基因、主要的典型通路以及上游调节因子。高盐诱导hAGT基因上调的一种可能机制是通过白细胞介素-6/Janus激酶/信号转导和转录激活因子3/AGT轴。
