title: Reactive oxygen species mediates disialoganglioside GD3-induced inhibition of ERK1/2 and matrix metalloproteinase-9 expression in vascular smooth muscle cells.
abstract: Sialic acid containing glycosphingolipids (gangliosides) are thought to play important roles in the function of various biological phenomena such as atherosclerosis. We have previously shown that the overexpression of the disialoganglioside (GD3) synthase gene effectively suppresses cell proliferation, cell cycle progression, and MMP-9 expression in vascular smooth muscle cells (VSMC). However, the issue of how the overexpression of GD3 synthase gene results in the inhibition of cellular responses in VSMC remains unclear. The findings herein demonstrate that overexpression of the GD3 synthase gene suppresses VSMC responses through the generation of reactive oxygen species (ROS). Superoxide and hydrogen peroxide were generated at increased levels in GD3 synthase gene transfectants in comparison with empty vector (EV) -transfected VSMC. This phenomenon was blocked by antioxidants such as N-acetyl-L-cysteine (NAC) and pyrrolidine dithiocarbamate (PDTC). Increased ROS generation was associated with a decreased endogenous antioxidant activity, increased lipid peroxidation, and mitochondrial DNA damage. Further studies revealed that the blockade of ROS function with antioxidants reversed the effect of GD3 synthase gene overexpression on VSMC proliferation and cell cycle regulation in response to platelet-derived growth factor (PDGF). In addition, we found that treatment with antioxidants reversed the decreased matrix metalloproteinase-9 (MMP-9) expression in response to TNF-alpha as determined by zymography and immunoblot in GD3 synthase gene transfectants. This recovery effect was characterized by the up-regulation of MMP-9 promoter activity, which was transcriptionally regulated at NF-kappaB and activation protein-1 (activating protein (AP) -1) sites in the MMP-9 promoter. These findings suggest that ROS may play a role in GD3 synthase gene-mediated VSMC phenotypic changes that may contribute to plaque instability in atherosclerosis.
authors.affiliation: Molecular and Cellular Glycobiology Unit, Department of Biological Science, SungKyunKwan University, Chunchun-Dong 300, Jangan-Gu, Suwon City, Kyunggi-Do 440-746, Korea.
authors.forename: Sung-Kwon
authors.initials: SK
authors.lastname: Moon
authors.forename: Sung-Koo
authors.initials: SK
authors.lastname: Kang
authors.forename: Cheorl-Ho
authors.initials: CH
authors.lastname: Kim
mesh_terms: D000818:Animals; D001011:Aorta; D001483:Base Sequence; D004249:DNA Damage; D017931:DNA Primers; D004272:DNA, Mitochondrial / Q000235:genetics; D005732:Gangliosides / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D015227:Lipid Peroxidation; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000235:genetics*; D061965:Matrix Metalloproteinase Inhibitors; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000235:genetics*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology*; D010957:Plasmids; D051381:Rats; D017382:Reactive Oxygen Species / Q000494:pharmacology*; D015183:Restriction Mapping; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013481:Superoxides / Q000378:metabolism; D014162:Transfection
chemical_list: D017931:DNA Primers; D004272:DNA, Mitochondrial; D005732:Gangliosides; D061965:Matrix Metalloproteinase Inhibitors; D017382:Reactive Oxygen Species; D013481:Superoxides; C026226:ganglioside, GD3; D006861:Hydrogen Peroxide; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020780:Matrix Metalloproteinase 9; D005978:Glutathione