ARACHIDONATE OMEGA 1 HYDROXYLATION IN HYPERTENSION

高血压中的花生四烯酸 Omega 1 羟基化

• 批准号: 6202241
• 负责人: Michal Laniado Schwartzman
• 金额: $ 24.35万
• 依托单位: NEW YORK MEDICAL COLLEGE
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-20 至 2000-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6202241
• 关键词: arachidonate; cytochrome P450; dietary sodium; disease /disorder model; fatty acid metabolism; gas chromatography mass spectrometry; gene expression; hydroxylation; hypertension; ion transport; isolation perfusion; isozymes; messenger RNA; nucleic acid probes; polymerase chain reaction; potassium channel; protein isoforms; renal tubule; sodium; spontaneous hypertensive rat; western blottings

20-HETE is a major cytochrome p450 (CYP) arachidonic acid (AA) metabolite in renal structures including proximal tubules, TALH and microvessels. 20- HETE has potent effects on the vasculature (vasoconstriction of renal arterioles) and tubules (inhibition of ion transport and K+ channel activity). It may, therefore, affect pro- and/or anti-hypertensive mechanisms. For example, an increase in 20-HETE synthesis in renal microvessels would bring about an increased vasoconstriction mechanisms influencing prohypertensive mechanism characterized by elevated vascular tone, increased GFR and RBF and sodium retention. On the other hand, increased tubular 20-HETE synthesis (proximal, TALH, macula densa) would be conducive to an increase in antihypertensive mechanisms operating at the level of regulation of salt and water balance and characterized by natriuresis and diuresis. The SHR is particularly interesting since it displays high (over expression) renal 20-HETE production. Furthermore, the development of hypertension in this model occurs between 5 and 9 weeks of age having been preceded by a many-fold increase in renal 20-HETE synthesis between 3 and 5 weeks. Inhibition of 2O-HETE synthesis in this stage is associated with blood pressure reduction suggesting a role for 20-HETE in the development of hypertension. This unique increase of 20- HETE production suggests the involvement of a distinct CYP isozyme(s) that is under regulatory control and that specifically metabolizes AA to 20- HETE. The CYP4A isoforms (4A1, 4A2 and 4A3), all of which are present in the rat kidney, are believed to be capable of metabolizing AA at the omega-carbon to yield 20-HETE. These isoforms, although sharing 66-98% homology, are localized to different renal structures and are exposed to different regulatory mechanisms. 20-HETE synthesis may be derived from different CYP4A isozymes in tubules and vessels. Alternatively, it may be formed by the same isozyme or a mixture of all three that are influenced by different regulatory elements. To understand the regulatory mechanisms underlying the renal synthesis of this important eicosanoid, we will characterize and correlate CYP4A protein and mRNA expression to AA omega- hydroxylation in tubular and vascular preparations from hypertensive and normotensive rats and study the influence of dietary salt. The contribution of CYP4A protein to 20-HETE synthesis in the kidney will be assessed by molecular cloning and expression of each isozyme following with analysis of its catalytic activity. The results of the proposed study will provide the biochemical basis for evaluating the functional significance of renal 20-HETE.

20-HETE 是一种主要的细胞色素 p450 (CYP) 花生四烯酸 (AA) 代谢物 肾脏结构，包括近端小管、TALH 和微血管。 20- HETE 对血管系统（肾血管收缩）有强大的影响 小动脉）和小管（离子转运和 K+ 通道的抑制 活动）。因此，它可能会影响促高血压和/或抗高血压药物 机制。 例如，肾脏中 20-HETE 合成的增加 微血管会增强血管收缩机制 影响以血管升高为特征的降压机制 张力、GFR 和 RBF 增加以及钠潴留。另一方面， 增加肾小管 20-HETE 合成（近端、TALH、致密斑）会 有利于增强抗高血压机制 盐和水平衡的调节水平，其特征为 排钠和利尿。 SHR 特别有趣，因为它 显示高（过度表达）肾脏 20-HETE 产量。此外， 该模型中高血压的发生发生在 5 至 9 周之间。 年龄之前肾脏 20-HETE 增加许多倍 合成时间为 3 至 5 周。抑制 2O-HETE 合成 分期与血压降低相关，表明 20-HETE 在高血压发展中的作用。这种独特的增长 20- HETE 的产生表明涉及一种独特的 CYP 同工酶， 受到监管控制并且专门将 AA 代谢为 20- 赫特。 CYP4A 同种型（4A1、4A2 和 4A3），所有这些都存在于 大鼠肾脏被认为能够代谢 AA omega-碳产生 20-HETE。这些异构体虽然共享 66-98% 同源性，定位于不同的肾脏结构并暴露于 不同的监管机制。 20-HETE合成可源自 肾小管和血管中存在不同的 CYP4A 同工酶。或者，也可以是 由相同的同工酶或受影响的所有三种同工酶的混合物形成 由不同的监管要素。了解监管机制 在这种重要的类二十烷酸的肾脏合成的基础上，我们将 表征 CYP4A 蛋白和 mRNA 表达并将其与 AA omega- 高血压和高血压的管状和血管制剂中的羟基化 血压正常的大鼠并研究饮食盐的影响。这 CYP4A 蛋白对肾脏 20-HETE 合成的贡献将是 通过分子克隆和每个同工酶的表达进行评估 并分析其催化活性。拟议研究的结果 将为评价功能性提供生化基础 肾20-HETE的意义。