Homocysteine stimulates nuclear factor kappaB activity and monocyte chemoattractant protein-1 expression in vascular smooth-muscle cells: a possible role for protein kinase C.
Monocyte chemoattractant protein-1 (MCP-1) is a potent chemokine that stimulates the migration of monocytes into the intima of arterial walls. Although many factors that induce MCP-1 expression have been identified, the effect of homocysteine on the expression of MCP-1 in atherogenesis and the underlying mechanisms are not entirely clear. The objective of the present study was to investigate the role of homocysteine in MCP-1 expression in human aorta vascular smooth-muscle cells (VSMCs). After VSMCs were incubated with homocysteine for various time periods, a nuclease protection assay and ELISA were performed. Homocysteine (0.05-0.2 mM) significantly increased the expression of MCP-1 mRNA (up to 2. 7-fold) and protein (up to 3.3-fold) in these cells. The increase in MCP-1 expression was associated with the activation of protein kinase C (PKC) as well as nuclear factor kappaB (NF-kappaB). Further investigation demonstrated that the activation of NF-kappaB was the result of a PKC-mediated reduction in the expression of inhibitory protein (IkappaBalpha) mRNA and protein in homocysteine-treated cells. Oxidative stress might also be involved in the activation of NF-kappaB by homocysteine in VSMCs. In conclusion, the present study has clearly demonstrated that the activation of PKC as well as superoxide production followed by activation of NF-kappaB is responsible for homocysteine-induced MCP-1 expression in VSMCs. These results suggest that homocysteine-stimulated MCP-1 expression via NF-kappaB activation may play an important role in atherogenesis.
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Department of Pharmacology, Institute of Cardiovascular Science and Medicine, Faculty of Medicine, University of Hong Kong, 1/F, Li Shu Fan Building, 5 Sassoon Road, Pokfulam, Hong Kong, People's Republic of China.
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D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D018932:Chemokine CCL2 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D006710:Homocysteine / Q000494:pharmacology*; D006801:Humans; D020672:I-kappa B Proteins; D008954:Models, Biological; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D023282:Nuclease Protection Assays; D018384:Oxidative Stress / Q000187:drug effects; D010750:Phosphoproteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D013482:Superoxide Dismutase / Q000037:antagonists & inhibitors / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
D018932:Chemokine CCL2; D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D010750:Phosphoproteins; D012333:RNA, Messenger; D006710:Homocysteine; D000072000:NF-KappaB Inhibitor alpha; D004247:DNA; D013482:Superoxide Dismutase; D011493:Protein Kinase C; D002118:Calcium