Hypertension & P450 w/w-1 Hykdroxylases and Epoxygenases

在之前的授权期内，由该计划项目支持的研究在小鼠中建立了Cyp4a14基因与高血压之间的联系。这里报告的初步数据表明，人类CYP4A11基因与高血压之间也存在联系。我们已经确定在人类基因组中有两个，而且很可能只有两个细胞色素P4A基因(细胞色素P4A11和细胞色素P4A22)。细胞色素P4A11以月桂酸或花生四烯酸为底物。我们发现，CYP4A22基因在肾脏中的表达非常低，并且不产生功能蛋白，这表明如果人类的高血压与CYP4A之间存在关联，那就是通过CYP4A11。我们研究了390名个体，120名非裔美国人和270名高加索人的CYP4A11基因外显子序列，这两组人平均分布在正常血压和高血压之间。一种突变(F434S)在高加索人群中被发现与高血压统计相关，但在非裔美国人组中没有。改变P4504A11蛋白中的这种氨基酸会使花生四烯酸羟基酶活性降低60%。在目前的建议中，我们将使用更大的人群(Framingham心脏研究)来从统计上证实我们当地队列的初步结果。Framingham的研究已经产生了大量的表型数据，这将有助于确定与该变异相关的表型。我们与这一队列的初步数据表明， 高加索男性，而不是女性。我们还将在非裔美国人队列(AASK)和来自加纳的队列中研究这种变异。还将检查CYP4A11的5‘-调节区 多态和它的内含子一样。我们将仔细检查来自CYP4A11的这些数据，以确定 单倍型与高血压的关系。最后，我们将对人类肾脏中另一个丰富的CYP基因--CYP2C8进行多态发现。我们认为，我们的初步数据清楚地表明，CYP4A11是研究高血压的候选基因。有相当多的证据表明花生四烯酸羟化和环氧化与高血压有关，这进一步强调了这些研究的重要性。

During the previous granting period studies supported by this Program Project established a link in the mouse between the Cyp4a14 gene and hypertension. Preliminary data reported here suggests that a link between the human CYP4A11 gene and hypertension also exists. We have established that there are two, and most likely only two CYP4A genes (CYP4A11 and CYP4A22) in the human genome. CYP4A11 uses either lauric acid or arachidonic acid as substrate. We have found that the CYP4A22 gene is very poorly expressed in kidney and does not produce a functional protein, indicating that if there is association between hypertension and CYP4A in humans, it is through CYP4A11. We have examined the exonic sequence of the CYP4A11 gene in 390 individuals, 120 African Americans and 270 Caucasians, both groups equally distributed between normotensive and hypertensive. A variant (F434S) is found to be statistically associated with hypertension in the Caucasian group but not in the African American group. Changing this amino acid in the P4504A11 protein reduces arachidonic acid hydroxylase activity by 60%. In the current proposal we will use a much larger population (Framingham Heart Study) to statistically confirm the preliminary results from our local cohort. The Framingham Study has generated extensive phenotypic data which will be helpful in determining the phenotype associated with this variant. Our prliminary data with this cohort indicates association in hypertension in Caucasian males but not females. We will also study this variant in an African-American cohort (AASK) and cohorts from Ghana. The 5'-regulatory region of CYP4A11 will also be examined for polymorphisms as will its introns. This data from CYP4A11 will be carefully examined to identify haplotype associations with hypertension. Finally, we will carry out polymorphism discovery on the other abundant CYP gene in human kidney, CYP2C8. We believe that our preliminary data clearly establish CYP4A11 as a candidate gene for investigation of hypertension. There is considerable evidence that arachidonic acid hydroxylation and expoxidation are related to hypertension which further emphasizes the importance of these studies.