Hyperhomocysteinemia activates nuclear factor-kappaB in endothelial cells via oxidative stress.
Hyperhomocysteinemia is an independent risk factor for cardiovascular diseases. Our previous studies demonstrated an important interaction between nuclear factor-kappaB (NF-kappaB) activation and homocysteine (Hcy)-induced chemokine expression in vascular smooth muscle cells and macrophages. The objective of the present study was to investigate the in vivo effect of hyperhomocysteinemia on NF-kappaB activation and the underlying mechanism of Hcy-induced NF-kappaB activation in endothelial cells. Hyperhomocysteinemia was induced in Sprague-Dawley rats after 4 weeks of a high-methionine diet. The activated form of NF-kappaB and increased level of superoxide anions were detected in the endothelium of aortas isolated from hyperhomocysteinemic rats. The underlying mechanism of Hcy-induced NF-kappaB activation was investigated in human umbilical cord vein endothelial cells and in human aortic endothelial cells. Incubation of cells with Hcy (100 micromol/L) activated IkappaB kinases (IKKalpha and IKKbeta), leading to phosphorylation and subsequent degradation of IkappaBalpha. As a consequence, NF-kappaB nuclear translocation, enhanced NF-kappaB/DNA binding activity, and increased transcriptional activity occurred. Additional analysis revealed a marked elevation of superoxide anion levels in Hcy-treated cells. Treatment of cells with a superoxide anion scavenger (polyethylene glycol-superoxide dismutase) or IkappaB kinase inhibitor (prostaglandin A(1)) could prevent Hcy-induced activation of IKK kinases and NF-kappaB in endothelial cells. In conclusion, these results suggest that Hcy-induced superoxide anion production may play a potential role for NF-kappaB activation in the early stages of atherosclerosis in the vascular wall via activation of IkappaB kinases.
Au-Yeung
Kathy K W
KK
National Centre for Agri-Food Research in Medicine, Department of Animal Science, University of Manitoba, Canada.
Woo
Connie W H
CW
Sung
Fion L
FL
Yip
Johnny C W
JC
Siow
Yaw L
YL
O
Karmin
K
D000818:Animals; D001011:Aorta / Q000737:chemistry / Q000166:cytology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D006710:Homocysteine / Q000494:pharmacology; D020138:Hyperhomocysteinemia / Q000378:metabolism*; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins / Q000378:metabolism; D008297:Male; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D018384:Oxidative Stress; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013481:Superoxides / Q000032:analysis / Q000378:metabolism
D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; C000606206:Nfkbia protein, rat; D006710:Homocysteine; D013481:Superoxides; D000072000:NF-KappaB Inhibitor alpha; D017346:Protein Serine-Threonine Kinases; D051550:I-kappa B Kinase