Aldosterone Synthase & Hypertension

描述（由申请人提供）：高血压是心肌梗死、心力衰竭、血管疾病、中风和肾衰竭的严重风险因素。肾素-血管紧张素-醛固酮系统（RAAS）在血压调节中起重要作用。醛固酮的不适当增加会导致与年龄相关的血压升高和其他心血管问题。醛固酮在肾上腺皮质的ZG中合成，并且醛固酮合成酶是其生物合成的限速酶。醛固酮合成酶由Cyp 11B 2基因编码，该基因启动子区-344位点存在T/C多态性。流行病学研究表明，Cyp 11 B2基因-344 T变异与高血压和心肌肥大有关。人Cyp 11B 2基因启动子区1 Kb内有3个SNPs，几乎完全连锁不平衡。这些SNP是rs 1799998（T/C在-344）、rs 10087214（C/T在-470）、rs 28659182（C/A在-663）。因此，变体-344 T几乎总是与变体-470 C、-663 A（命名为单倍型-I）一起出现，并且变体-344 C几乎总是与变体-470 T、-663 T（命名为单倍型-II）一起出现。我们通过在HPRT位点敲入含有单体型I或单体型II的hCyp 11B 2基因来产生转基因小鼠。与含有单倍型II的转基因动物相比，含有单倍型I的转基因小鼠肾上腺和肾脏中的hCyp 11B 2 mRNA水平增加。此外，与含有hCyp 11B 2基因的单倍型II的转基因动物相比，含有单倍型I的雄性转基因动物具有升高的血压。高盐（4%NaCl饮食）和血管紧张素-II管理含有hCyp 11B 2基因的单倍型-I的转基因小鼠的血压增加相比，单倍型-II。因此，我们的假设是，转录因子强烈结合到hCyp 11B 2基因的核苷酸序列含有单倍型-I相比，单倍型-II，并增加其表达。这增加了含有单倍型I的人类受试者的组织或血浆醛固酮水平。与-344 C等位基因相比，醛固酮产生调节改变的长期后果导致含有-344 T等位基因的人类受试者的血压和心血管并发症增加。这些转基因小鼠将用于了解这些单倍型对雄性和雌性动物血压调节的作用。转基因小鼠也可用于开发新的治疗试剂，以降低血压和心血管并发症。

DESCRIPTION (provided by applicant): Hypertension is a serious risk factor for myocardial infarction, heart failure, vascular disease, stroke, and renal failure. The renin-angiotensin-aldosterone system (RAAS) plays an important role in the regulation of blood pressure. Inappropriate increase of aldosterone causes age-related increase in blood pressure and other cardiovascular problems. Aldosterone is synthesized in the ZG of the adrenal cortex and aldosterone synthase is the rate limiting enzyme in its biosynthesis. Aldosterone synthase is coded by Cyp11B2 gene and the human gene has a T/C polymorphism located at -344 in its promoter. Epidemiological studies have suggested that variant -344T of Cyp11B2 gene is associated with hypertension and myocardial hypertrophy. Human Cyp11B2 gene has three SNPs in 1 Kb of its promoter that are in almost complete linkage dis-equilibrium. These SNPs are rs1799998 (T/C at -344), rs10087214 (C/T at -470), rs28659182 (C/A at -663). Thus variant -344T almost always occurs with variants -470C, -663A (named haplotype-I, and variant -344C almost always occurs with variants, - 470T, -663T (named haplotype-II). We have generated transgenic mice by knocking in hCyp11B2 gene containing either haplotype-I or haplotype-II at the HPRT locus. Transgenic mice containing haplotype-I have increased hCyp11B2 mRNA level in the adrenals and kidneys as compared to transgenic animals containing haplotype-II. In addition, male transgenic animals containing haplotype-I have increased blood pressure as compared to transgenic animals containing haplotype-II of hCyp11B2 gene. High salt (4% NaCl diet) and angiotensin-II administration increases blood pressure in transgenic mice containing haplotype-I of hCyp11B2 gene as compared to haplotype-II. Therefore, our hypothesis is that transcription factors bind strongly to the nucleotide sequence of hCyp11B2 gene containing haplotype-I as compared to haplotype-II, and increase its expression. This increases tissue or plasma aldosterone level in human subjects containing haplotype-I. The long term consequence of altered regulation of aldosterone production leads to an increase in blood pressure and cardiovascular complications in human subjects containing -344T allele as compared to -344C allele. These transgenic mice will be used to understand the role of these haplotypes on blood pressure regulation in male and female animals. Transgenic mice may also be used to develop new therapeutic reagents to reduce blood pressure and cardiovascular complications.