Nitric oxide inhibition of homocysteine-induced human endothelial cell apoptosis by down-regulation of p53-dependent Noxa expression through the formation of S-nitrosohomocysteine.
Hyperhomocysteinemia is believed to induce endothelial dysfunction and promote atherosclerosis; however, the pathogenic mechanism has not been clearly elucidated. In this study, we examined the molecular mechanism by which homocysteine (HCy) causes endothelial cell apoptosis and by which nitric oxide (NO) affects HCy-induced apoptosis. Our data demonstrated that HCy caused caspase-dependent apoptosis in cultured human umbilical vein endothelial cells, as determined by cell viability, nuclear condensation, and caspase-3 activation and activity. These apoptotic characteristics were correlated with reactive oxygen species (ROS) production, lipid peroxidation, p53 and Noxa expression, and mitochondrial cytochrome c release following HCy treatment. HCy also induced p53 and Noxa expression and apoptosis in endothelial cells from wild type mice but not in the p53-deficient cells. The NO donor S-nitroso-N-acetylpenicillamine, adenoviral transfer of inducible NO synthase gene, and antioxidants (alpha-tocopherol and superoxide dismutase plus catalase) but not oxidized SNAP, 8-Br-cGMP, nitrite, and nitrate, suppressed ROS production, p53-dependent Noxa expression, and apoptosis induced by HCy. The cytotoxic effect of HCy was decreased by small interfering RNA-mediated suppression of Noxa expression, indicating that Noxa up-regulation plays an important role in HCy-induced endothelial cell apoptosis. Overexpression of inducible NO synthase increased the formation of S-nitroso-HCy, which was inhibited by the NO synthase inhibitor N-monomethyl-l-arginine. Moreover, S-nitroso-HCy did not increase ROS generation, p53-dependent Noxa expression, and apoptosis. These results suggest that up-regulation of p53-dependent Noxa expression may play an important role in the pathogenesis of atherosclerosis induced by HCy and that an increase in vascular NO production may prevent HCy-induced endothelial dysfunction by S-nitrosylation.
Lee
Seon-Jin
SJ
Vascular System Research Center and Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chunchon, Kangwon-do 200-701, Korea.
Kim
Ki-Mo
KM
Namkoong
Seung
S
Kim
Chun-Ki
CK
Kang
Yun-Chul
YC
Lee
Hansoo
H
Ha
Kwon-Soo
KS
Han
Jeong-A
JA
Chung
Hun-Taeg
HT
Kwon
Young-Guen
YG
Kim
Young-Myeong
YM
D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects*; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006710:Homocysteine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology*; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D009569:Nitric Oxide / Q000378:metabolism / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D014470:Umbilical Cord
D000975:Antioxidants; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C110881:S-nitro-N-acetylpenicillamine; D016159:Tumor Suppressor Protein p53; D006710:Homocysteine; C079202:S-nitrosohomocysteine; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D010396:Penicillamine