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Title: Arsenite induces endothelial cytotoxicity by down-regulation of vascular endothelial nitric oxide synthase

Abstract

Epidemiological studies have demonstrated a high association of inorganic arsenic exposure with vascular diseases. Recent research has also linked this vascular damage to impairment of endothelial nitric oxide synthase (eNOS) function by arsenic exposure. However, the role of eNOS in regulating the arsenite-induced vascular dysfunction still remains to be clarified. In our present study, we investigated the effect of arsenite on Akt1 and eNOS and its involvement in cytotoxicity of vascular endothelial cells. Our study demonstrated that arsenite decreased the protein levels of both Akt1 and eNOS accompanied with increased levels of ubiquitination of total cell lysates. We found that inhibition of the ubiquitin-proteasome pathway by MG-132 could partially protect Akt1 and eNOS from degradation by arsenite together with a proportional protection from the arsenite-induced cytoxicity. Moreover, up-regulation of eNOS protein expression significantly attenuated the arsenite-induced cytotoxicity and eNOS activity could be significantly inhibited after incubation with arsenite for 24 h in a cell-free system. Our study indicated that endothelial eNOS activity could be attenuated by arsenite via the ubiquitin-proteasome-mediated degradation of Akt1/eNOS as well as via direct inhibition of eNOS activity. Our study also demonstrated that eNOS actually played a protective role in arsenite-induced cytoxicity. These observations supported themore » hypothesis that the impairment of eNOS function by arsenite is one of the mechanisms leading to vascular changes and diseases.« less

Authors:
 [1];  [2];  [2];  [2];  [2];  [2]
  1. Division of Environmental Health and Occupational Medicine, National Health Research Institutes, 100 Shih-Chuan 1st Road, Kaohsiung 807 (China). E-mail: tctsou@nhri.org.tw
  2. Division of Environmental Health and Occupational Medicine, National Health Research Institutes, 100 Shih-Chuan 1st Road, Kaohsiung 807 (China)
Publication Date:
OSTI Identifier:
20722028
Resource Type:
Journal Article
Resource Relation:
Journal Name: Toxicology and Applied Pharmacology; Journal Volume: 208; Journal Issue: 3; Other Information: DOI: 10.1016/j.taap.2005.03.001; PII: S0041-008X(05)00113-4; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ARSENIC; DAMAGE; ENDOTHELIUM; INCUBATION; INHIBITION; NITRIC OXIDE; PROTEINS; SAFETY; TOXICITY; VASCULAR DISEASES

Citation Formats

Tsou, T.-C., Tsai, F.-Y., Hsieh, Y.-W., Li, L.-A., Yeh, S.C, and Chang, L.W. Arsenite induces endothelial cytotoxicity by down-regulation of vascular endothelial nitric oxide synthase. United States: N. p., 2005. Web. doi:10.1016/j.taap.2005.03.001.
Tsou, T.-C., Tsai, F.-Y., Hsieh, Y.-W., Li, L.-A., Yeh, S.C, & Chang, L.W. Arsenite induces endothelial cytotoxicity by down-regulation of vascular endothelial nitric oxide synthase. United States. doi:10.1016/j.taap.2005.03.001.
Tsou, T.-C., Tsai, F.-Y., Hsieh, Y.-W., Li, L.-A., Yeh, S.C, and Chang, L.W. Tue . "Arsenite induces endothelial cytotoxicity by down-regulation of vascular endothelial nitric oxide synthase". United States. doi:10.1016/j.taap.2005.03.001.
@article{osti_20722028,
title = {Arsenite induces endothelial cytotoxicity by down-regulation of vascular endothelial nitric oxide synthase},
author = {Tsou, T.-C. and Tsai, F.-Y. and Hsieh, Y.-W. and Li, L.-A. and Yeh, S.C and Chang, L.W.},
abstractNote = {Epidemiological studies have demonstrated a high association of inorganic arsenic exposure with vascular diseases. Recent research has also linked this vascular damage to impairment of endothelial nitric oxide synthase (eNOS) function by arsenic exposure. However, the role of eNOS in regulating the arsenite-induced vascular dysfunction still remains to be clarified. In our present study, we investigated the effect of arsenite on Akt1 and eNOS and its involvement in cytotoxicity of vascular endothelial cells. Our study demonstrated that arsenite decreased the protein levels of both Akt1 and eNOS accompanied with increased levels of ubiquitination of total cell lysates. We found that inhibition of the ubiquitin-proteasome pathway by MG-132 could partially protect Akt1 and eNOS from degradation by arsenite together with a proportional protection from the arsenite-induced cytoxicity. Moreover, up-regulation of eNOS protein expression significantly attenuated the arsenite-induced cytotoxicity and eNOS activity could be significantly inhibited after incubation with arsenite for 24 h in a cell-free system. Our study indicated that endothelial eNOS activity could be attenuated by arsenite via the ubiquitin-proteasome-mediated degradation of Akt1/eNOS as well as via direct inhibition of eNOS activity. Our study also demonstrated that eNOS actually played a protective role in arsenite-induced cytoxicity. These observations supported the hypothesis that the impairment of eNOS function by arsenite is one of the mechanisms leading to vascular changes and diseases.},
doi = {10.1016/j.taap.2005.03.001},
journal = {Toxicology and Applied Pharmacology},
number = 3,
volume = 208,
place = {United States},
year = {Tue Nov 01 00:00:00 EST 2005},
month = {Tue Nov 01 00:00:00 EST 2005}
}
  • A natural ligand of peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}), 15-deoxy-{delta}{sup 12,14}-prostaglandin J{sub 2} (15d-PGJ{sub 2}), decreases endothelial nitric oxide synthase (eNOS) expression by an unknown mechanism. Here we found that 15d-PGJ{sub 2}-induced eNOS reduction is inversely associated with heat shock protein 70 (HSP70) induction in endothelial cells. Treatment of cells with 15d-PGJ{sub 2} decreased eNOS protein expression in a concentration- and time-dependent manner, but independently of PPAR{gamma} with no effect on mRNA levels. Although 15d-PGJ{sub 2} elicited endothelial apoptosis, inhibition of both pan-caspases and cathepsins failed to reverse reduction of eNOS protein. Interestingly, we observed that 15d-PGJ{sub 2} induced HSP70more » in a dose-dependent manner. Immunoprecipitation and heat shock treatment demonstrated that eNOS reduction was strongly related to HSP70 induction. Cellular fractionation revealed that treatment with 15d-PGJ{sub 2} increased eNOS distribution 2.5-fold from soluble to insoluble fractions. These findings provide new insights into mechanisms whereby eNOS regulation by 15d-PGJ{sub 2} is related to HSP70 induction.« less
  • Diesel exhaust particles (DEP) are an important cause of air pollution and are thought to be responsible for some respiratory ailments, but the exact mechanism is not known. We evaluated whether DEP inhibit nitric oxide (NO) synthesis in bronchi as No is present in the exhaled air and has a physiological role in the respiratory tract. Aortic rings were also examined for comparison. We observed that acetylcholine (ACh) induced contraction of the bronchi was partially attenuated by the simultaneous release of NO. When bronchial rings were incubated either with N{sup G}-methyl-L-arginine (L-NMA): an inhibitor of NO synthase (NOS) or withmore » DEP, the contraction to ACh was abolished. The source of the NOS was the bronchial epithelium and this endothelial-constitutive NOS was demonstrated by immunohistochemistry. DEP like L-NMA inhibited the ACh induced endothelium dependent relaxation in the aortic rings. The inhibition of NO release by DEP and L-NMA from bronchial and aortic rings was also confirmed by a selective NO electrode. We conclude that inhibition of NO availability by DEP may in part be responsible for the adverse respiratory effects seen by inhalation of these particles in polluted air. 27 refs., 6 figs.« less
  • We previously showed that ginsenosides increase nitric oxide (NO) production in vascular endothelium and that ginsenoside Rg3 (Rg3) is the most active one among ginseng saponins. However, the mechanism for Rg3-mediated nitric oxide production is still uncertain. In this study, we determined whether Rg3 affects phosphorylation and expression of endothelial nitric oxide synthase (eNOS) in ECV 304 human endothelial cells. Rg3 increased both the phosphorylation and the expression of eNOS in a concentration-dependent manner and a maximal effect was found at 10 {mu}g/ml of Rg3. The enzyme activities of phosphatidylinositol 3-kinase (PI3-kinase), c-Jun N-terminal kinase (JNK), and p38 kinase weremore » enhanced as were estrogen receptor (ER)- and glucocorticoid receptor (GR)-dependent reporter gene transcriptions in Rg3-treated endothelial cells. Rg3-induced eNOS phosphorylation required the ER-mediated PI3-kinase/Akt pathway. Moreover, Rg3 activates AMP-activated protein kinase (AMPK) through up-regulation of CaM kinase II and Rg3-stimulated eNOS phosphorylation was reversed by AMPK inhibition. The present results provide a mechanism for Rg3-stimulated endothelial NO production.« less