Soluble Epoxide Hydrolase Polymorphisms

描述(由申请人提供)：本申请中描述的研究的长期目标是确定人类中可溶性环氧化物水解酶(SEH)基因多态性的生理学和临床相关性。大量研究表明，sEH参与了外源性和内源性环氧化物底物的代谢。外源底物包括在我们的饮食中发现的诱变和致癌的环氧化物。内源性底物包括调节血管张力的脂肪酸环氧化物，sEH基因敲除小鼠的血压明显低于野生型小鼠。人类的SEH活性差异超过500倍，然而，这种差异背后的机制仍不清楚。在本申请中描述的初步研究表明，在人类sEH蛋白中至少存在6个氨基酸变体。基于异源表达实验，我们发现这些变异氨基酸中至少有两个在体外显著改变了人sEH蛋白的比活性。这些结果表明，人类sEH活性的可变性可能部分是由于sEH基因的遗传多态，这些多态可能影响个体对外源性或内源性环氧化物的易感性或反应。基于这些初步结果，本应用的具体目的是：1.利用异源蛋白表达系统构建和进一步鉴定人类sEH变异蛋白；2.比较sEH基因与人肝脏中sEH酶的活性和含量；以及3.比较一组高血压和正常血压人群的sEH基因。这些特定的目的旨在检验这样的假设，即人类sEH基因的多态在体外和体内都会导致sEH表型的改变。这项工作将为理解sEH基因多态在决定人类疾病进展中与外源性和内源性环氧化物代谢相关的机制作用提供基础。

DESCRIPTION (provided by applicant): The long-term objective of the research described in this application is to determine the physiological and clinical relevance of soluble epoxide hydrolase (sEH) polymorphisms in humans. Numerous studies have shown that sEH is involved in the metabolism of exogenous and endogenous epoxide substrates. Exogenous substrates include mutagenic and carcinogenic epoxides found in our diet. Endogenous substrates include fatty acid epoxides, which regulate vascular tone, and sEH knockout mice have significantly lower blood pressure than do wild-type mice. sEH activity in humans varies by more than 500-fold, however, the mechanisms that underlie this variability remain unknown. Preliminary studies described in this application reveal the existence of at least 6 amino acid variants in the human sEH protein. Based on heterologous expression experiments, we show that at least 2 of these variant amino acids significantly alter the specific activity of the human sEH protein in vitro. These results suggest that sEH activity variability in humans may be partially due to genetic polymorphisms in the sEH gene, and that these polymorphisms may influence an individual's susceptibility or response to exogenous or endogenous epoxides. Based on these preliminary results, the specific aims of this application are to: 1. Construct and further characterize human sEH variant proteins using a heterologous protein expression system, 2. Compare sEH genotypes with sEH enzyme activity and amount in human liver samples, and, 3. Compare sEH genotypes in a group of hypertensive and normotensive humans. These specific aims are designed to test the hypothesis that polymorphisms in the human sEH gene result in an altered sEH phenotype in vitro and in vivo. This work will provide a basis for understanding the mechanistic roles of sEH polymorphisms in determining human disease progression as related to exogenous and endogenous epoxide metabolism.