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Overexpression of cellular glutathione peroxidase rescues homocyst(e)ine-induced endothelial dysfunction.

ABSTRACT: Homocyst(e)ine (Hcy) inhibits the expression of the antioxidant enzyme cellular glutathione peroxidase (GPx-1) in vitro and in vivo, which can lead to an increase in reactive oxygen species that inactivate NO and promote endothelial dysfunction. In this study, we tested the hypothesis that overexpression of GPx-1 can restore the normal endothelial phenotype in hyperhomocyst(e)inemic states. Heterozygous cystathionine beta-synthase-deficient (CBS((-/+))) mice and their wild-type littermates (CBS((+/+))) were crossbred with mice that overexpress GPx-1 [GPx-1((tg+)) mice]. GPx-1 activity was 28% lower in CBS((-/+))/GPx-1((tg-)) compared with CBS((+/+))/GPx-1((tg-)) mice (P < 0.05), and CBS((-/+)) and CBS((+/+)) mice overexpressing GPx-1 had 1.5-fold higher GPx-1 activity compared with GPx-1 nontransgenic mice (P < 0.05). Mesenteric arterioles of CBS((-/+))/GPx-1((tg-)) mice showed vasoconstriction to superfusion with beta-methacholine and bradykinin (P < 0.001 vs. all other groups), whereas nonhyperhomocyst(e)inemic mice [CBS((+/+))/GPx-1((tg-)) and CBS((+/+))/GPx-1((tg+)) mice] demonstrated dose-dependent vasodilation in response to both agonists. Overexpression of GPx-1 in hyperhomocyst(e)inemic mice restored the normal endothelium-dependent vasodilator response. Bovine aortic endothelial cells (BAEC) were transiently transfected with GPx-1 and incubated with dl-homocysteine (HcyH) or l-cysteine. HcyH incubation decreased GPx-1 activity in sham-transfected BAEC (P < 0.005) but not in GPx-1-transfected cells. Nitric oxide release from BAEC was significantly decreased by HcyH but not cysteine, and GPx-1 overexpression attenuated this decrease. These findings demonstrate that overexpression of GPx-1 can compensate for the adverse effects of Hcy on endothelial function and suggest that the adverse vascular effects of Hcy are at least partly mediated by oxidative inactivation of NO.

SUBMITTER: Weiss N

PROVIDER: S-EPMC60083 | biostudies-literature | 2001 Oct

REPOSITORIES: biostudies-literature

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Overexpression of cellular glutathione peroxidase rescues homocyst(e)ine-induced endothelial dysfunction.

Weiss N N Zhang Y Y YY Heydrick S S Bierl C C Loscalzo J J

Proceedings of the National Academy of Sciences of the United States of America 20011016 22

Homocyst(e)ine (Hcy) inhibits the expression of the antioxidant enzyme cellular glutathione peroxidase (GPx-1) in vitro and in vivo, which can lead to an increase in reactive oxygen species that inactivate NO and promote endothelial dysfunction. In this study, we tested the hypothesis that overexpression of GPx-1 can restore the normal endothelial phenotype in hyperhomocyst(e)inemic states. Heterozygous cystathionine beta-synthase-deficient (CBS((-/+))) mice and their wild-type littermates (CBS( ...[more]

PMID: 11606774

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Project description:Oxygen radicals are commonly accepted mediators in the tumour necrosis factor-mediated nuclear factor kappa B (NF kappa B) signalling cascade, but evidence for their role during interleukin-1 (IL-1) signalling is lacking. To test the involvement of hydroperoxides we investigated whether IL-1-induced NF kappa B activation could be influenced by glutathione peroxidases (GPx). These enzymes remove hydroperoxides with various specificities for the hydroperoxide substrate. By overexpressing phospholipid hydroperoxide glutathione peroxidase (PHGPx), which characteristically reacts with lipophilic hydroperoxides, the roles of H2O2 and lipid hydroperoxides were assessed. A human umbilical endothelial cell line, ECV 304, was stably transfected with the genes for both PHGPx and selenophosphate synthetase (selD), which provides selenophosphate for selenoprotein biosynthesis. When grown in selenium-deficient culture medium, the double-transfected clone (ECVPHGPx+SelD+) expressed 5-fold higher (P<0.005) PHGPx activity (measured by phosphatidylcholine hydroperoxide removal) than controls. The rate of H2O2 removal was also significantly (P<0.01) higher in this clone. When grown with high levels of extracellular selenium (up to 100 nM selenite), PHGPx activity and H2O2 removal were enhanced substantially in control cells and transfected cells. Under these conditions, PHGPx activity was 1.7-fold (P<0.005) higher in ECVPHGPx+SelD+, but H2O2 removal was the same as in controls. IL-1-induced NF kappa B activation was inhibited by selenium supplementation in control cells. In ECVPHGPx+SelD+ under conditions of selenium restriction, IL-1 induced NF kappa B activation only to a similar extent as under conditions of selenium supplementation in controls, and activation was abolished with 50 nM sodium selenite. These results show that overexpressed PHGPx is sufficient to inhibit NF kappa B activation, and suggests that NF kappa B activation by IL-1 is mediated by a preferential substrate of PHGPx, such as a fatty acid hydroperoxide, rather than by H2O2, the preferred substrate of the more abundant cytosolic GPx.

Dataset Information

Overexpression of cellular glutathione peroxidase rescues homocyst(e)ine-induced endothelial dysfunction.

Publications

Overexpression of cellular glutathione peroxidase rescues homocyst(e)ine-induced endothelial dysfunction.

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