Novel Mechanism for Endothelial Dysfunction

Itō, Akira; Tsao, Philip S.; Adimoolam, Shanthi; Kimoto, Masumi; Ogawa, Tadashi; Cooke, John P.

doi:10.1161/01.cir.99.24.3092

Cited by 550 publications

(118 citation statements)

References 13 publications

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“…In this regard, our group and others have shown that overexpression of DDAH-1 results in increased NO production (9,36). Furthermore, oxidized low density lipoprotein and tumor necrosis factor ␣ have been shown to decrease DDAH activity, leading to decreased endothelial NO production (37). It has also been demonstrated that 4-hyrdoxynonenal, the highly reactive oxidant product of lipid peroxidation, inhibits DDAH activity and leads to impaired NO generation through the formation of Michael addition products in the catalytic triad of DDAH (36).…”

Section: Discussionmentioning

confidence: 85%

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Role of Dimethylarginine Dimethylaminohydrolases in the Regulation of Endothelial Nitric Oxide Production

Pope

Karrupiah

Kearns

et al. 2009

Journal of Biological Chemistry

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Reduced NO is a hallmark of endothelial dysfunction, and among the mechanisms for impaired NO synthesis is the accumulation of the endogenous nitric-oxide synthase inhibitor asymmetric dimethylarginine (ADMA). Free ADMA is actively metabolized by the intracellular enzyme dimethylarginine dimethylaminohydrolase (DDAH), which catalyzes the conversion of ADMA to citrulline. Decreased DDAH expression/activity is evident in disease states associated with endothelial dysfunction and is believed to be the mechanism responsible for increased methylarginines and subsequent ADMA-mediated endothelial nitric-oxide synthase impairment. Two isoforms of DDAH have been identified; however, it is presently unclear which is responsible for endothelial ADMA metabolism and NO regulation. The current study investigated the effects of both DDAH-1 and DDAH-2 in the regulation of methylarginines and endothelial NO generation. Results demonstrated that overexpression of DDAH-1 and DDAH-2 increased endothelial NO by 24 and 18%, respectively. Moreover, small interfering RNA-mediated down-regulation of DDAH-1 and DDAH-2 reduced NO bioavailability by 27 and 57%, respectively. The reduction in NO production following DDAH-1 gene silencing was associated with a 48% reduction in L-Arg/ADMA and was partially restored with L-Arg supplementation. In contrast, L-Arg/ADMA was unchanged in the DDAH-2-silenced cells, and L-Arg supplementation had no effect on NO. These results clearly demonstrate that DDAH-1 and DDAH-2 manifest their effects through different mechanisms, the former of which is largely ADMA-dependent and the latter ADMA-independent. Overall, the present study demonstrates an important regulatory role for DDAH in the maintenance of endothelial function and identifies this pathway as a potential target for treating diseases associated with decreased NO bioavailability. Endothelium-derived nitric oxide (NO)2 is a potent vasodilator that plays a critical role in maintaining vascular homeostasis through its antiatherogenic and antiproliferative effects on the vascular wall. Altered NO biosynthesis has been implicated in the pathogenesis of cardiovascular disease, and evidence from animal models and clinical studies suggests that accumulation of the endogenous nitric-oxide synthase (NOS) inhibitors, asymmetric dimethylarginine (ADMA) and N Gmethyl-L-arginine (L-NMMA) contribute to reduced NO generation and disease pathogenesis (1, 2). ADMA and L-NMMA are derived from the proteolysis of methylated arginine residues on various proteins. The methylation is carried out by a group of enzymes referred to as protein-arginine methyltransferases (3). Protein arginine methylation has been identified as an important post-translational modification involved in the regulation of DNA transcription, protein function, and cell signaling (4, 5). Upon proteolysis of methylated proteins, free methylarginines are released and can function as competitive inhibitors of NOS activity. The intracellular levels of these free methylarginines are regulated through the...

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Section: Discussionmentioning

confidence: 85%

“…PCR and Western blot analysis have revealed that the endothelium contains mRNA and protein for both DDAH-1 and DDAH-2 (8,11,14,15,37,41). However, in order to assess the relative contribution of each enzyme, a detailed analysis of the enzyme kinetics of each isoform is necessary.…”

Section: Discussionmentioning

confidence: 99%

Role of Dimethylarginine Dimethylaminohydrolases in the Regulation of Endothelial Nitric Oxide Production

Pope

Karrupiah

Kearns

et al. 2009

Journal of Biological Chemistry

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“…To date, six different isoforms of the enzyme have been identified with each subtype exhibiting various levels of activity, substrate specificity, and tissue distribution (23,26). These methylarginines are subsequently degraded by the enzyme dimethylarginine dimethylaminohydrolase, which catalyzes the hydrolysis of ADMA or L-NMMA to L-citrulline and dimethylamine or monomethylamine (27)(28)(29).…”

mentioning

confidence: 99%

Evidence for the Pathophysiological Role of Endogenous Methylarginines in Regulation of Endothelial NO Production and Vascular Function

Cardounel

Cui

Samouilov

et al. 2007

Journal of Biological Chemistry

224

172

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In endothelium, NO is derived from endothelial NO synthase (eNOS)-mediated L-arginine oxidation. Endogenous guanidinomethylated arginines (MAs), including asymmetric dimethylarginine (ADMA) and N G -methyl-L-arginine (L-NMMA), are released in cells upon protein degradation and are competitive inhibitors of eNOS. However, it is unknown whether intracellular MA concentrations reach levels sufficient to regulate endothelial NO production. Therefore, the dose-dependent effects of ADMA and L-NMMA on eNOS function were determined. Kinetic studies demonstrated that the K m for L-arginine is 3.14 M with a V max of 0.14 mol mg The biological significance of guanidino-methylated arginine derivatives has been known since the inhibitory actions of N G -methyl-L-arginine (L-NMMA) 3 on macrophage induced cytotoxicity were first demonstrated. It was subsequently realized that these effects were mediated through inhibition of NO release (1). NO has been demonstrated as a critical effector molecule in the maintenance of vascular function (2-4). In the vasculature, NO is derived from the oxidation of L-Arg, catalyzed by the constitutively expressed enzyme, eNOS (5-7). This endothelial-derived NO diffuses from the vascular endothelium into the smooth muscle cell layer where it activates soluble guanylate cyclase leading to smooth muscle relaxation (2-4). In addition to its role in the maintenance of vascular tone, NO helps to maintain the anti-atherogenic character of the normal vascular wall. NO, in concert with various cell signaling molecules, has been demonstrated to maintain smooth muscle cell quiescence and as such, counteracts pro-proliferative agents, specifically those involved in the propagation of athero-proliferative disorders (8 -14). As such, eNOS dysfunction is an early symptom of vascular disease and is manifested through insufficient NO bioavailability. Several potential causes of NO deficiency in disease settings have been proposed. Among these, high circulating levels of the endogenous methylarginine NOS inhibitor asymmetric dimethylarginine (ADMA) has been hypothesized to be of particular importance (15)(16)(17)(18)(19)(20)(21). In neurons and the brain, it has been shown that the methyl arginine L-NMMA is also present, however, the levels of this methylarginine have not been previously considered in studies evaluating vascular dysfunction (22).ADMA and L-NMMA are endogenous inhibitors of NOS and are derived from the proteolysis of methylated arginine residues on various proteins. The methylation is carried out by a group of enzymes referred to as protein-arginine methyltransferase (23). Subsequent proteolysis of proteins containing methylarginine groups leads to the release of free methylarginine into the cytoplasm, and if sufficient levels are reached NO production from NOS would be inhibited (24, 25). To date, six different isoforms of the enzyme have been identified with each

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“…In this respect, it was shown that methylation of L-Arg is enhanced in endothelial cells in response to hypercholesterolemia, with the formation of dimethyl arginine, an inactive substrate for NO production (34,35). In the current study, we present data showing that HOCl reacts with L-Arg, resulting in the formation of chlorinated metabolites.…”

Section: Discussionmentioning

confidence: 50%

l-Arginine Chlorination Products Inhibit Endothelial Nitric Oxide Production

Zhang¹,

Reiter²,

Eiserich³

et al. 2001

Journal of Biological Chemistry

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Novel Mechanism for Endothelial Dysfunction

Abstract: These results suggest that the endothelial vasodilator dysfunction observed in hypercholesterolemia may be due to reduced degradation of ADMA, the endogenous inhibitor of NOS.

Cited by 550 publications

References 13 publications

Role of Dimethylarginine Dimethylaminohydrolases in the Regulation of Endothelial Nitric Oxide Production

Role of Dimethylarginine Dimethylaminohydrolases in the Regulation of Endothelial Nitric Oxide Production

Evidence for the Pathophysiological Role of Endogenous Methylarginines in Regulation of Endothelial NO Production and Vascular Function

l-Arginine Chlorination Products Inhibit Endothelial Nitric Oxide Production

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