Genetics of Hypertension

描述(申请人提供)：高血压是心肌梗死、心力衰竭、血管疾病、中风和肾功能衰竭的严重危险因素。血管紧张素原(AGT)基因与人类原发性高血压相关，糖皮质激素和IL-6治疗可增加AGT基因的表达。以前的研究表明，AGT基因的变异-6A与高加索人和日本人血浆AGT水平升高和血压升高有关。然而，与含有-6G等位基因的转基因小鼠相比，含有1.2kb启动子的Hagt基因-6A等位基因的转基因小鼠没有表现出转录增加或血压升高。我们发现Hagt基因有三个额外的SNPs(A/G at-1670、C/G at-1562和T/G at-1561)以及变异体-1670A、-1562C和-1561T几乎总是与变异体-6A一起出现。因此，HAGT基因可分为-6A单倍型(含-6A、-1561T、-1562C、-1670A)和-6G单倍型(含-6G、-1561G、-15652、-1670G)。瞬时转染实验表明，与-6G单倍型相比，携带-6A单倍型的报告构建体在肝和肾细胞中糖皮质激素和IL-6诱导的启动子活性分别增加了4倍和5倍。为了了解糖皮质激素和IL-6对Hagt基因-6A和-6G单倍型转录和体内血压调节的作用，我们重组了180kb长的BAC DNA(包括Hagt基因5‘-侧翼区的116kb，所有5个外显子和4个内含子，以及Hagt基因3’-UTR区的54kb)，并获得了含有Hagt基因-6A或-6G单倍型和人肾素基因的双转基因小鼠。我们的研究表明：(A)与-6G单倍型相比，含有-6A单倍型的转基因小鼠的血压和(B)肝和肾脏中Hagt mRNA的表达增加。我们现在将使用这些转基因小鼠来了解糖皮质激素和IL-6在体内情况下对Hagt基因表达和血压的作用。这些研究将为降低高血压患者的血压提供新的策略。

DESCRIPTION (provided by applicant): Hypertension is a serious risk factor for myocardial infarction, heart failure, vascular disease, stroke, and renal failure. Angiotensinogen (AGT) gene locus is associated with human essential hypertension and its expression is increased by glucocorticoid and IL-6 treatment. Previous studies have shown that variant -6A of the AGT gene is associated with increased plasma AGT level and increased blood pressure in Caucasian and Japanese population. However, transgenic mice containing 1.2 Kb of the promoter with -6A allele of the hAGT gene neither show increased transcription nor increased blood pressure compared to transgenic mice containing -6G allele. We have found that hAGT gene has three additional SNPs (A/G at -1670, C/G at -1562 and T/G at -1561) and variants -1670A, - 1562C, and -1561T almost always occur with variant -6A. Therefore hAGT gene may be subdivided in either -6A haplotype (containing -6A, -1561T, -1562C, -1670A) or -6G haplotype (containing -6G, -1561G, -15652, -1670G). Our transient transfection assays show that reporter construct with -6A haplotype has four fold increased glucocorticoid and five fold increased IL-6 induced promoter activity as compared to the reporter construct with -6G haplotype in liver and kidney cells. In order to understand the role of glucocorticoids and IL-6 on transcription of -6A and -6G haplotypes of the hAGT gene and on the regulation of blood pressure in an in vivo situation, we have re-combineered 180 Kb long BAC DNA (containing 116 Kb of the 5'-flanking region, all five exons and four introns, and 54 Kb of the 3'-UTR of the hAGT gene) and produced double transgenic mice containing either -6A or - 6G haplotype of the hAGT gene and human renin gene. Our studies suggest that: (a) blood pressure and (b) hAGT mRNA in the liver and kidney is increased in transgenic mice containing -6A haplotype as compared to -6G haplotype. We will now use these transgenic mice to understand the role of glucocorticoids and IL-6 on hAGT gene expression and blood pressure in an in vivo situation. These studies will provide new strategies to reduce blood pressure in hypertensive subjects.