CYTOCHROME P-450 ARACHIDONIC ACID METABOLISM & REGULATION OF RENAL ION TRANSPORT

CYTOCHROME P-450 花生四烯酸代谢

• 批准号: 6105361
• 负责人: Matthew Douglas Breyer
• 金额: $ 16.26万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-02-01 至 1999-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6105361
• 关键词: cyclic AMP; cytochrome P450; eicosanoid metabolism; ion transport; isozymes; kidney function; laboratory mouse; laboratory rabbit; peroxisome; polymerase chain reaction; prostaglandin endoperoxide synthase; prostaglandin inhibitors; prostaglandin receptor; renal tubular transport; sodium ion; tissue /cell culture; troglitazone; western blottings

The renal metabolism of arachidonic acid (AA) produces a diverse array of biologically active lipid mediators which potently regulate renal hemodynamics and ion transport along the nephron. Cyclooxygenase mediated prostanoid formation has been extensively studied and an important physiologic role, established. The kidney also possess a robust cytochrome P450 (CYP450) system which rapidly metabolizes arachidonate to several bioactive lipids including the epoxyeicosatrienoic acids (EETs) and omega/omega-1 AA metabolites (the hydroxyeicosatetraenoic acids or HETEs). Accumulating evidence supports an intimal association between renal CYP450 activity and the regulation of systemic blood pressure. Inhibition of renal CYP450 activity induces hypertension and the CYP450 AA metabolite, 20-HETE inhibits CI-absorption in the thick ascending limb (TAL). 20-HETE is actively formed by only a few CYP450s, and the CYP4A family appear to be the relevant isoforms in the kidney. In specific aim #1 we propose to characterize the role of specific CYP4A isoforms and their omega/omega-1 AA metabolites in regulating ion transport to murine microperfused thick ascending limbs (TAL). Studies in mice with targeted disruption of CYP4A10 and 4A14 should allow us to define roles for specific CYP450 isoforms in regulating TAL ion transport. The expression of CYP4As has recently been shown to be under the control of a fatty acid activated transcription factor, known as peroxisome proliferator activated receptor alpha (PPARalpha). We have recently mapped the intra-renal expression of three PPAR isoforms (PPARalpha, gamma, and delta) and find PPARalpha is highly expressed in proximal tubule and TAL, whereas PPARgamma is primarily expressed in the collecting duct. Preliminary data suggests activation and TAL, whereas PPARgamma enhances Na+ absorption in collecting duct. In specific aim #2, we propose to characterize the effects of PPAR activation on epithelial Na+ transport in cultured cortical collecting ducts (CCDs) as well as in whole animal Na+ balance studies. Finally, the production of the EETs is mediated by distinct families of CYP450s including CYP2C and CYP2B isoforms Evidence suggests 5,6-EET and 14,15-EET potently regulate transport in the renal collecting duct. In specific aim #3 we propose to further examine the role of CYP450 AA epoxygenases in regulating ion transport along the nephron. Roles for the prostaglandin EP1 receptor in mediating the effect of 5,6-EET in microperfused CCDs will be tested, as will effects of adenoviral mediated CYP450 expression on transport in cultured CCDs. It is our hope these studies will help define the role of CYP450-AA metabolism in regulating renal ion transport, its impact on Na+ excretion, and ultimately the control of systemic blood pressure.

花生四烯酸（AA）的肾脏代谢产生多种 具有生物活性的脂质介质，可有效调节肾脏 沿肾单位的血流动力学和离子传输。环加氧酶介导 前列腺素的形成已被广泛研究，并且是一个重要的 生理作用，已确定。肾脏还拥有强大的细胞色素 P450（CYP450）系统可将花生四烯酸快速代谢为多种 生物活性脂质，包括环氧二十碳三烯酸 (EET) 和 omega/omega-1 AA 代谢物（羟基二十碳四烯酸或 HETE）。 越来越多的证据支持肾 CYP450 之间的内膜关联 活动和全身血压的调节。抑制 肾脏 CYP450 活性诱发高血压和 CYP450 AA 代谢物， 20-HETE 抑制厚升肢 (TAL) 的 CI 吸收。 20-HETE 仅由少数 CYP450 主动形成，而 CYP4A 家族似乎 是肾脏中的相关亚型。在具体目标#1中，我们建议 描述特定 CYP4A 亚型及其 omega/omega-1 的作用 AA 代谢物调节离子向小鼠微灌注浓浆的转运 上肢（TAL）。对小鼠进行靶向破坏 CYP4A10 的研究 4A14 应该允许我们定义特定 CYP450 同工型的作用 调节 TAL 离子传输。最近，CYP4As 的表达 显示处于脂肪酸激活转录的控制下 因子，称为过氧化物酶体增殖物激活受体α （PPARα）。我们最近绘制了三种肾内表达图 PPAR 亚型（PPARα、γ 和 δ）并发现 PPARα 高度 在近曲小管和 TAL 中表达，而 PPARgamma 主要在 表达于集合管。初步数据表明激活和 TAL，而 PPARgamma 增强集合管中 Na+ 的吸收。在 具体目标#2，我们建议表征 PPAR 激活的影响 培养的皮质集合管 (CCD) 中上皮 Na+ 转运的影响 以及整个动物 Na+ 平衡研究。最后，生产 EET 由 CYP450 的不同家族介导，包括 CYP2C 和 CYP2B 亚型 有证据表明 5,6-EET 和 14,15-EET 有效调节 在肾集合管中运输。在具体目标#3中，我们建议 进一步研究CYP450 AA加氧酶在调节离子中的作用 沿肾单位运输。前列腺素 EP1 受体在 将测试 5,6-EET 在微灌注 CCD 中的介导作用，如下所示 腺病毒介导的 CYP450 表达对转运的影响 培养的 CCD。我们希望这些研究将有助于确定 CYP450-AA代谢调节肾离子转运及其对Na+的影响 排泄，最终控制全身血压。