花生四烯酸细胞色素P450代谢物在肾脏生理和疾病中的作用(英文)

肾脏疾病在全球范围内都是导致死亡的重要原因。肾脏微血管功能失调在肾病的发生与发展中发挥着不可忽视的作用。药理学和生物化学等领域的许多实验方法已被用来研究花生四烯酸的细胞色素P450 (cytochrome P450, CYP450)代谢物对肾脏微血管功能的调控作用。在肾脏中,CYP450表氧化酶代谢物环氧二十碳三烯酸(epoxyeicosatrienoic acids, EETs)主要在肾脏微血管产生。EETs可以通过舒张血管、降低血压、抗细胞凋亡、抗炎等多个方面发挥肾脏保护作用。CYP450表氧化酶代谢物EETs可作为肾脏疾病的治疗靶点。然而,在肾脏发生疾病时,肾脏微血管产生EETs的能力会显著降低。近来,用转基因动物过表达CYP450表氧化酶或用可溶性环氧化物水解酶(soluble epoxide hydrolase, sEH)抑制剂也均证实增加EETs水平具有明显的肾脏保护作用。本综述将重点讨论花生四烯酸的CYP450代谢物EETs在肾脏生理及疾病状态下具体的调控机制。     

环氧化物水解酶与人类疾病的关系

环氧化物水解酶(epoxide hydratase,EH)普遍存在于哺乳动物体内,它们参与一系列环氧化物诸如多环芳烃环氧化物、环氧二十碳三烯酸(epoxyeicosatrienoic acid,EET)的代谢,具有调节新陈代谢、解毒、调节信号分子三大功能,并且与人类多种疾病相关联。其中微粒体环氧化物水解酶(microsomal epoxide hydrolase,mEH)与多种癌症易感性相关联;可溶性环氧化物水解酶(soluble epoxide hydrolase,sEH)在心肌肥大、糖尿病、高血压等疾病的治疗中起着重要作用。本文主要综述了mEH和sEH的分子生物学特性,mEH多态性与癌症易感性的关系,以及sEH活性与多种疾病的关系。     

可溶性表氧化物水解酶与脂代谢

可溶性表氧化物水解酶(soluble epoxide hydrolase,sEH)在哺乳动物体内广泛存在。研究发现,sEH可以降解表氧二十碳三烯酸(epoxyeicosatrienoic acids,EETs)以及其他脂肪酸表氧化物。EETs具有广泛的心血管系统保护及抗炎作用,故sEH因其与心血管疾病的关系而受到关注。新近研究显示,sEH与脂质代谢密切相关,并与其C端水解酶区域和N端磷酸酶区域的不同活性有关。进一步深入探讨sEH的作用机制,将为研究脂质调节紊乱相关的代谢疾病提供一个新的治疗靶点。本文对sEH两端酶活性,及其与脂质代谢调节的研究进展予以综述。     

环氧二十碳三烯酸与肺部疾病的研究进展

环氧二十碳三烯酸(epoxyeicosatrienoic acids, EETs)是一种具有强大生物活性的内生脂质环氧化合物。EETs在肺组织疾病中具有抗炎症反应、抗氧化活性、诱导肺血管收缩、促进细胞增殖等作用,可成为多种肺部疾病防治的新型靶点。本文就EETs的作用机制及其在肺部疾病中的研究进展进行了归纳总结。     

环氧二十碳三烯酸在心血管系统稳态中的生理功能

细胞色素P450表氧化酶与其代谢产物EETs在心血管系统的稳态中具有重要的作用。目前的研究表明,EETs具有调节血管张力,降低血压,促进血管新生以及抗炎等生理作用。深入研究细胞色素P450表氧化酶与EETs在心血管系统中的保护作用及其作用机制,有助于为探索心血管疾病新的治疗策略提供理论依据。     

花生四烯酸的细胞色素P450酶代谢途径产物EETs和20-HETE在血管功能调控中的作用

花生四烯酸(arachidonic acids, AA)广泛存在于生物体内,并可通过多种途径代谢成为具有强大生物学功能的脂质小分子。其中,经细胞色素P450酶代谢途径产生的环氧二十碳三烯酸(epoxyeicosatrienoic acids, EETs)及20-羟基二十碳四烯酸(20-hydroxyeicosatetraenoic acid, 20-HETE)的作用备受关注,尤其是在血管稳态中的作用。血管功能调控是维持血管稳态的基础,主要通过对血管的结构和(或)生物学活性的影响而实现。近30年来,EETs及20-HETE在血管功能调控中的作用及机制被广泛研究。本文分别就EETs和20-HETE在血管新生和血管炎症反应等方面的研究进展逐一进行综述。总的来说,在生物学活性方面,EETs主要体现为舒张血管和抑制血管炎症,而20-HETE则可以促进血管收缩和血管炎症。两者在血管新生方面的作用类似,都可以促进血管新生。另外,本文还对EETs和20-HETE在常见的血管性疾病(如高血压和心肌缺血)中的作用进行了探讨,对其中的作用机制进行了分析和总结,并对基于EETs和20-HETE的血管性疾病靶向治疗提出了展望。     

花生四烯酸细胞色素P450表氧化酶代谢物EETs的内源性心血管保护作用

花生四烯酸(arachidonic acid, AA)是生物体内最丰富的多不饱和脂肪酸,其代谢产物具有广泛的生物学活性。环氧二十碳三烯酸(epoxyeicosatrienoic acids, EETs)是AA经细胞色素P450表氧化酶(cytochrome P450 epoxygenase, CYP450)代谢产生的内源性小分子化合物,近20年的研究表明EETs具有广泛的心血管保护作用,是重要的内源性心血管保护因子。EETs不仅可以改善不同病因导致的心脏重构,抑制心肌肥厚,减轻不同因素导致的心肌损伤,还能明显改善上述病理过程所导致的血流动力学紊乱和心功能损害。在血管保护方面,最早的研究证明EETs是一种内皮来源的超极化因子,可以通过作用于内皮细胞和平滑肌上的钙离子敏感通道而发挥血管舒张作用,随后研究发现,EETs可能有更多非超极化效应而产生降压、改善冠状动脉血供、调节肺动脉压力等作用。此外,EETs还具有显著的内皮保护效应,可以抑制内皮细胞的炎症反应和黏附作用,抑制血小板聚集,促进纤溶和血管的新生。EETs还能改善主动脉重构,包括抑制动脉粥样硬化、主动脉外膜纤维化和主动脉钙化。EETs心血管保护作用的分子机制是多方面的,EETs可通过调控多个信号通路从而调节不同病理生理环节,是一种多靶点内源性心血管保护因子。因此研究EETs在心血管系统中的生理和病理生理作用有利于阐明心血管疾病的内源性保护机制,为心血管疾病的防治提供新策略。本文综述了EETs的内源性心血管保护作用和机制,以期为该领域的转化研究提供新的思路。     

在小鼠中抑制可溶性表氧化物水解酶(sEH)可以促进胆固醇逆向转运和斑块逆转

<正>目前已经知道脂肪细胞通过ABCA1将胆固醇转运到胞外apoA-I,且这个过程能促进血浆HDL增加,有利于保护心血管。而s EH是一种代谢内源性环氧二十碳三烯酸(EETs)的胞浆酶,EETs在脂肪细胞中表达很丰富。作者的团队之前发现脂肪细胞中sEH的抑制剂t-AUCB能增加ABCA1的水平,本文便研究内源性s EH的抑制对心血管系统的保护机制。在ldlr缺陷小鼠脂肪组织中,发现相比标准喂养(SCD),促动脉粥样硬化饮食(ATD)下s EH活性显著增加,而在t-AUCB     

细胞色素P450酶的结构、功能与应用研究进展

细胞色素P450 (cytochrome P450,CYP)酶是广泛存在于微生物、动植物及人体中与膜结合的血红蛋白类酶,具有氧化、环氧化、羟化、去甲基化等多种生物催化活性。CYP酶在药物、类固醇、脂溶性维生素和许多其他类型化学物质的代谢中具有重要作用,其在异源物质的解毒、药物相互作用和内分泌功能等领域的研究是热点问题。本综述对CYP的结构、功能、临床应用与开发前景进行了概述,并对其最新的研究现状和发展前景进行探讨。     

表氧化二十碳三烯对eNOS磷酸化水平的影响及其相关信号转导通路

内皮源性一氧化氮合酶(eNOS)是一氧化氮(NO)参与的血管稳态调节过程中的关键酶. 多种体液因子和机械刺激都可以通过磷酸化修饰调节eNOS的活性, 但具体的信号转导通路因刺激物不同而异. 最近发现花生四烯酸细胞色素P450(CYP)表氧化酶代谢产物表氧化二十碳三烯(EETs)可以显著上调eNOS的蛋白表达并增强其活性, 但其分子机制尚不清楚. 通过在4代以内培养的牛主动脉内皮细胞中直接加入外源性EETs和转染CYP表氧化酶基因CYP2C11和CYPF87V, 并同时给予实验组不同信号转导抑制剂进行干预, 观察其对总的eNOS表达及其在Ser1179 和Thr497位点磷酸化水平的影响. 结果显示, 内外源性EETs均可以显著上调eNOS的蛋白表达并增强及其在Ser1179和Thr497位点的磷酸化水平; PI3K抑制剂LY294002可以阻断EETs对eNOS-Ser1179的磷酸化上调作用, 但它对eNOS-Thr(P)497并无影响, 而Akt抑制剂却可以抑制eNOS在这两个位点的磷酸化, 且这两种抑制剂都可以阻断EETs对eNOS的蛋白表达上调作用.结果提示: (i) EETs对eNOS的活性调节可能与PI3K/Akt所介导的eNOS-Ser1179和Akt所介导的eNOS- Thr497磷酸化水平改变相关; (ii) PI3K/Akt信号通路可能参与了EETs对eNOS的蛋白表达上调过程.     

The anti-inflammatory effects of soluble epoxide hydrolase inhibitors are independent of leukocyte recruitment

Excess leukocyte recruitment to the lung plays a central role in the development or exacerbation of several lung inflammatory diseases including chronic obstructive pulmonary disease. Epoxyeicosatrienoic acids (EETs) are cytochrome P-450 metabolites of arachidonic acid reported to have multiple biological functions, including blocking of leukocyte recruitment to inflamed endothelium in cell culture through reduction of adhesion molecule expression. Inhibition of the EET regulatory enzyme, soluble epoxide hydrolase (sEH) also has been reported to have anti-inflammatory effects in vivo including reduced leukocyte recruitment to the lung. We tested the hypothesis that the in vivo anti-inflammatory effects of sEH inhibitors act through the same mechanisms as the in vitro anti-inflammatory effects of EETs in a rat model of acute inflammation following exposure to tobacco smoke. Contrary to previously published data, we found that sEH inhibition did not reduce tobacco smoke-induced leukocyte recruitment to the lung. Furthermore, sEH inhibition did not reduce tobacco smoke-induced adhesion molecule expression in the lung vasculature. Similarly, concentrations of EETs greater than or equal to their reported effective dose did not reduce TNFα induced expression of the adhesion molecules. These results suggest that the anti-inflammatory effects of sEH inhibitors are independent of leukocyte recruitment and EETs do not reduce the adhesion molecules responsible for leukocyte recruitment in vitro. This demonstrates that the widely held belief that sEH inhibition prevents leukocyte recruitment via EET prevention of adhesion molecule expression is not consistently reproducible.     

Soluble epoxide hydrolase: Gene structure,expression and deletion

Mammalian soluble epoxide hydrolase (sEH) converts epoxides to their corresponding diols through the addition of a water molecule. sEH readily hydrolyzes lipid signaling molecules, including the epoxyeicosatrienoic acids (EETs), epoxidized lipids produced from arachidonic acid by the action of cytochrome p450s. Through its metabolism of the EETs and other lipid mediators, sEH contributes to the regulation of vascular tone, nociception, angiogenesis and the inflammatory response. Because of its central physiological role in disease states such as cardiac hypertrophy, diabetes, hypertension, and pain sEH is being investigated as a therapeutic target. This review begins with a brief introduction to sEH protein structure and function. sEH evolution and gene structure are then discussed before human small nucleotide polymorphisms and mammalian gene expression are described in the context of several disease models. The review ends with an overview of studies that have employed the sEH knockout mouse model.     

Epoxy Fatty Acids and Inhibition of the Soluble Epoxide Hydrolase Selectively Modulate GABA Mediated Neurotransmission to Delay Onset of Seizures

In the brain, seizures lead to release of large amounts of polyunsaturated fatty acids including arachidonic acid (ARA). ARA is a substrate for three major enzymatic routes of metabolism by cyclooxygenase, lipoxygenase and cytochrome P450 enzymes. These enzymes convert ARA to potent lipid mediators including prostanoids, leukotrienes and epoxyeicosatrienoic acids (EETs). The prostanoids and leukotrienes are largely pro-inflammatory molecules that sensitize neurons whereas EETs are anti-inflammatory and reduce the excitability of neurons. Recent evidence suggests a GABA-related mode of action potentially mediated by neurosteroids. Here we tested this hypothesis using models of chemically induced seizures. The level of EETs in the brain was modulated by inhibiting the soluble epoxide hydrolase (sEH), the major enzyme that metabolizes EETs to inactive molecules, by genetic deletion of sEH and by direct administration of EETs into the brain. All three approaches delayed onset of seizures instigated by GABA antagonists but not seizures through other mechanisms. Inhibition of neurosteroid synthesis by finasteride partially blocked the anticonvulsant effects of sEH inhibitors while the efficacy of an inactive dose of neurosteroid allopregnanolone was enhanced by sEH inhibition. Consistent with earlier findings, levels of prostanoids in the brain were elevated. In contrast, levels of bioactive EpFAs were decreased following seizures. Overall these results demonstrate that EETs are natural molecules which suppress the tonic component of seizure related excitability through modulating the GABA activity and that exploration of the EET mediated signaling in the brain could yield alternative approaches to treat convulsive disorders.     

Aging,Estrogen Loss and Epoxyeicosatrienoic Acids (EETs)

Inflammation is a key element in many cardiovascular diseases. Both estrogen loss, caused by menopause, and aging have inflammatory consequences. Epoxyeicosatrienoic acids (EETs) are anti-inflammatory molecules synthesized by various cytochrome P450 (Cyp) enzymes from arachidonic acid. EETs are in the third (Cytochrome P450) pathway of arachindonic acid metabolism, others being cyclooxygenases and lipoxygenases. We hypothesized that aging and estrogen loss would reduce levels of anti-inflammatory EETs. Adult (6 mo) and aged (22 mo) ovariectomized rats with (OP) and without (Ovx) 17-∃-estradiol replacement were used in this study. Mass spectrometry was used to measure levels of EETs and their metabolites, dihydroxyeicosatrienoic acids (DHETs). Levels of Cyp2C2, Cyp2C6, and Cyp2J2, the principal Cyps responsible for EETs synthesis, as well as soluble epoxide hydrolase (sEH), which metabolizes EETS to DHETs, were determined via western blot. Overall Cyp levels decreased with age, though Cyp2C6 increased in the liver. sEH was increased in the kidney with estrogen replacement. Despite protein changes, no differences were measured in plasma or aortic tissue levels of EETs. However, plasma 14,15 DHET was increased in aged Ovx, and 5,6 DHET in adult OP. In conclusion neither aging nor estrogen loss decreased the anti-inflammatory EETs in the cardiovascular system.     

Reno-protective mechanisms of epoxyeicosatrienoic acids in cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of mortality worldwide, and it is well known that end-stage renal disease (ESRD) is a profound consequence of the progression of CVD. Present treatments only slow CVD progression to ESRD, and it is imperative that new therapeutic strategies are developed to prevent the incidence of ESRD. Because epoxyeicosatrienoic acids (EETs) have been shown to elicit reno-protective effects in hypertensive animal models, the current review will focus on addressing the reno-protective mechanisms of EETs in CVD. The cytochrome P-450 epoxygenase catalyzes the oxidation of arachidonic acid to EETs. EETs have been identified as endothelium-derived hyperpolarizing factors (EDHFs) with vasodilatory, anti-inflammatory, antihypertensive, and antiplatelet aggregation properties. EETs also have profound effects on vascular migration and proliferation and promote angiogenesis. The progression of CVD has been linked to decreased EETs levels, leading to the concept that EETs should be therapeutically targeted to prevent end-organ damage associated with CVD. However, EETs are quickly degraded by the enzyme soluble epoxide hydrolase (sEH) to their less active diols, dihydroxyeicosatrienoic acids (DHETs). As such, one way to increase EETs level is to inhibit their degradation to DHETs by using sEH inhibitors. Inhibition of sEH has been shown to effectively reduce blood pressure and organ damage in experimental models of CVD. Another approach to target EETs is to develop EET analogs with improved solubility and resistance to auto-oxidation and metabolism by sEH. For example, stable ether EET analogs dilate afferent arterioles and lower blood pressure in hypertensive rodent animal models. EET agonists also improve insulin signaling and vascular function in animal models of metabolic syndrome.     

Epoxyeicosatrienoic acids (EETs): metabolism and biochemical function

Epoxyeicosatrienoic acids (EETs), which are synthesized from arachidonic acid by cytochrome P450 epoxygenases, function primarily as autocrine and paracrine effectors in the cardiovascular system and kidney. They modulate ion transport and gene expression, producing vasorelaxation as well as anti-inflammatory and pro-fibrinolytic effects. EETs are incorporated into the sn-2 position of phospholipids and are rapidly mobilized when a cell is treated with a Ca(2+) ionophore, suggesting that they may play a role in phospholipid-mediated signal transduction processes. Soluble epoxide hydrolase (sEH) converts EETs to dihydroxyeicosatrienoic acids (DHETs), and inhibition of sEH is a potential approach for enhancing the biological activity of EETs. EETs also undergo chain-elongation and beta-oxidation, and the accumulation of partial beta-oxidation products increases when sEH is inhibited. Some functional effects of EETs occur through activation of either the guanine nucleotide binding protein Galphas or the Src signal transduction pathways, suggesting that EETs act by binding to membrane receptors. However, other evidence indicates that the modulation of gene expression occurs through an intracellular action of EETs. Because of the diversity of biochemical and functional responses produced by EETs, it is doubtful that a single mechanism or signal transduction pathway can account for all of their actions.     

Genetic disruption of soluble epoxide hydrolase is protective against streptozotocin-induced diabetic nephropathy

Cytochrome P-450 (CYP) epoxygenases metabolize arachidonic acid into epoxyeicosatrienoic acids (EETs), which play important roles in regulating cardiovascular functions. The anti-inflammatory, antiapoptotic, proangiogenic, and antihypertensive properties of EETs suggest a beneficial role for EETs in diabetic nephropathy. Endogenous EET levels are maintained by a balance between synthesis by CYP epoxygenases and hydrolysis by epoxide hydrolases into physiologically less active dihydroxyeicosatrienoic acids. Genetic disruption of soluble epoxide hydrolase (sEH/EPHX2) results in increased EET levels through decreased hydrolysis. This study investigated the effects of sEH gene disruption on diabetic nephropathy in streptozotocin-induced diabetic mice. Streptozotocin-induced diabetic manifestations were attenuated in sEH-deficient mice relative to wild-type controls, with significantly decreased levels of Hb A(1c), creatinine, and blood urea nitrogen and urinary microalbumin excretion. The sEH-deficient diabetic mice also had decreased renal tubular apoptosis that coincided with increased levels of antiapoptotic Bcl-2 and Bcl-xl, and decreased levels of the proapoptotic Bax. These effects were associated with activation of the PI3K-Akt-NOS3 and AMPK signaling cascades. sEH gene inhibition and exogenous EETs significantly protected HK-2 cells from TNFα-induced apoptosis in vitro. These findings highlight the beneficial role of the CYP epoxygenase-EETs-sEH system in the pathogenesis of diabetic nephropathy and suggest that the sEH inhibitors available may be potential therapeutic agents for this condition.     

Regulation of forskolin-induced cAMP production by cytochrome P450 epoxygenase metabolites of arachidonic acid in HEK293 cells

Introduction  

Cytochrome P450 epoxygenases metabolize arachidonic acid to epoxyeicosatrienoic acids (EETs), which in turn are converted to dihydroxyeicosatrienoic acids (DHETs) by soluble epoxide hydrolase (sEH). EETs are known to modulate a number of vascular and renal functions, but the exact signaling mechanism(s) of these EET-mediated effects remains unknown.