PPARs in CYP450 Dependent Regulation of Kidney Function

缺乏细胞色素P450 4a14的小鼠的高血压表现提供了明确的证据 将细胞色素P450系统与血压控制联系起来的证据。尽管其他证据表明细胞色素P450衍生的花生四烯酸代谢产物(CyP450-AA代谢物)在肾微血管效应和肾盐吸收中起中介作用，但对其分子靶点的鉴定仍然难以确定。包括盐皮质激素和雄激素受体在内的核受体激活异常是男性高血压的公认原因。最近，另一组核受体--过氧化物酶体增殖物激活受体(PPAR)的突变也被发现会导致人类高血压。PPAR还被证明既能在转录水平上调节细胞色素P450的表达，又能被细胞色素P450氨基酸代谢产物结合和激活。这个项目的目的是验证这样的假设，即PPARGamma不仅是CYP450 AA代谢物的关键靶点，介导这一家族化合物的上皮和微血管效应，而且还调节CYP450环氧合酶的表达。在特定目标1中提出的研究：将使用Cre/Lox系统有条件地从小鼠的集合管和其他肾单位片段中删除一个“成簇的”PPARGamma等位基因，以检验CYP450和PPARGamma之间在调节肾上皮细胞离子运输方面的相互作用。还将研究CYP450衍生的花生四烯酸代谢产物作为PPAR伽马配体的潜力。具体目标2将研究PPARGamma在调节CYP450 AA环氧酶产物(EETs)和DHETs在调节血管张力和血压中的作用。通过这些研究，我们希望建立一个新的分子途径，有助于通过细胞色素P450调节血压。

The demonstration of hypertension in mice lacking Cytochrome P450 4a14 provides unequivocal evidence linking the CYP450 system with blood pressure control. Although other evidence implicates Cytochrome P450 derived arachidonate metabolites (CYP450-AA metabolites) as mediating both renal microvascular effects and effects on renal salt absorption, identification of a molecular target of CYP450-AA metabolites has remained elusive. Abnormalities in activation of nuclear receptors including mineralocorticoid and androgen receptors are well-established causes of hypertension in man. More recently mutations in another group of nuclear receptors, the peroxisome proliferator activated receptors (PPARs), have also been found to result in human hypertension. PPARs have also been shown both to transcriptionally modulate the expression of CYP450s and also bind and be activated by CYP450 AA metabolites. This goal of this project is to test the hypothesis that PPARgamma are not only key target of CYP450 AA metabolites, mediating both the epithelial and microvascular effects of this family of compounds, but also modulate the expression of CYP450 epoxygenases. The studies proposed in Specific aim 1: will examine the interaction between CYP450s and PPARgamma in regulating renal epithelial ion transport, using the Cre/Lox system to conditionally delete a "floxed" PPARgamma allele from the mouse collecting duct and other nephron segments. The potential of CYP450 derived arachidonate metabolites as PPARgamma ligands will also be studied. Specific Aim 2 will examine the role PPARgamma in modulating CYP450 AA epoxygenase products (EETs) and DHETs in modulating vascular tone and blood pressure. Through these studies we hope to establish a novel molecular pathway contributing to the regulation of blood pressure by CYP450s.