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Targeting of Metallothionein by L-Homocysteine A Novel Mechanism for Disruption of Zinc and Redox Homeostasis

Targeting of Metallothionein by L-Homocysteine A Novel Mechanism for Disruption of Zinc and Redox... Targeting of Metallothionein by L-Homocysteine A Novel Mechanism for Disruption of Zinc and Redox Homeostasis John C. Barbato, Otilia Catanescu, Kelsey Murray, Patricia M. DiBello, Donald W. Jacobsen Objective—L-homocysteine and/or L-homocystine interact in vivo with albumin and other extracellular proteins by forming mixed-disulfide conjugates. Because of its extremely rich cysteine content, we hypothesized that metallothio- nein, a ubiquitous intracellular zinc-chaperone and superoxide anion radical scavenger, reacts with L-homocysteine and that homocysteinylated-metallothionein suffers loss of function. Methods and Results— S-homocysteinylated-metallothionein was resolved in lysates of cultured human aortic endothelial cells in the absence and presence of reduced glutathione by SDS-PAGE and identified by Western blotting and phosphorimaging. Using zinc-Sepharose chromatography, L-homocysteine was shown to impair the zinc-binding capacity of metallothionein even in the presence of reduced glutathione. L-Homocysteine induced a dose-dependent increase in intracellular free zinc in zinquin-loaded human aortic endothelial cells within 30 minutes, followed by the appearance of early growth response protein-1 within 60 minutes. In addition, intracellular reactive oxygen species dramatically increased 6 hours after L-homocysteine treatment. In vitro studies demonstrated that L-homocysteine is a potent inhibitor of the superoxide anion radical scavenging ability of metallothionein. Conclusion—These studies provide the first evidence that L-homocysteine targets intracellular metallothionein http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Arteriosclerosis, Thrombosis, and Vascular Biology Wolters Kluwer Health

Targeting of Metallothionein by L-Homocysteine A Novel Mechanism for Disruption of Zinc and Redox Homeostasis

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References (45)

ISSN
1079-5642
eISSN
1524-4636
DOI
10.1161/01.ATV.0000251536.49581.8a
pmid
17082481
Publisher site
See Article on Publisher Site

Abstract

Targeting of Metallothionein by L-Homocysteine A Novel Mechanism for Disruption of Zinc and Redox Homeostasis John C. Barbato, Otilia Catanescu, Kelsey Murray, Patricia M. DiBello, Donald W. Jacobsen Objective—L-homocysteine and/or L-homocystine interact in vivo with albumin and other extracellular proteins by forming mixed-disulfide conjugates. Because of its extremely rich cysteine content, we hypothesized that metallothio- nein, a ubiquitous intracellular zinc-chaperone and superoxide anion radical scavenger, reacts with L-homocysteine and that homocysteinylated-metallothionein suffers loss of function. Methods and Results— S-homocysteinylated-metallothionein was resolved in lysates of cultured human aortic endothelial cells in the absence and presence of reduced glutathione by SDS-PAGE and identified by Western blotting and phosphorimaging. Using zinc-Sepharose chromatography, L-homocysteine was shown to impair the zinc-binding capacity of metallothionein even in the presence of reduced glutathione. L-Homocysteine induced a dose-dependent increase in intracellular free zinc in zinquin-loaded human aortic endothelial cells within 30 minutes, followed by the appearance of early growth response protein-1 within 60 minutes. In addition, intracellular reactive oxygen species dramatically increased 6 hours after L-homocysteine treatment. In vitro studies demonstrated that L-homocysteine is a potent inhibitor of the superoxide anion radical scavenging ability of metallothionein. Conclusion—These studies provide the first evidence that L-homocysteine targets intracellular metallothionein

Journal

Arteriosclerosis, Thrombosis, and Vascular BiologyWolters Kluwer Health

Published: Jan 1, 2007

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