Glycobiology Advance Access originally published online on July 6, 2005
Glycobiology 2005 15(11):1094-1101; doi:10.1093/glycob/cwj003
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Modification of oligosaccharides by reactive oxygen species decreases sialyl lewis x-mediated cell adhesion
2 Department of Biochemistry, Hyogo College of Medicine, 1-1 Mukogawa, Nishinomiya, Hyogo 663-8501, Japan; 3 Division of Molecular Cell Biology, Department of Biomolecular Sciences, Saga University Faculty of Medicine, 5-1-1 Nabeshima, Saga, Saga 849-8501, Japan; 4 CREST Project, Japan Science and Technology Agency; 5 Department of Biochemistry, Osaka University Medical School, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; 6 Department of Molecular Genetics, Kochi University Medical School, Kohasu, Oko-cho, Nankoku, Kochi 783-8505, Japan; 7 Departments of Biochemistry and Chemistry, The Ohio State University, 876 Biological Sciences Building, 484 West 12th Avenue, Columbus, OH 43210
1 To whom correspondence should be addressed; e-mail: suzuki{at}hyo-med.ac.jp
Received on March 3, 2005; revised on June 22, 2005; accepted on June 23, 2005
Modification of cell surface oligosaccharides by reactive oxygen species (ROS) and the biological effect of such modifications on cell adhesion were investigated. Treatment of HL60, a human promyelocyte leukemia cell line, with ROS, generated by a combination of hypoxanthine and xanthine oxidase (HX/XO), decreased the sialic acid content on the cell surface, as indicated by a flow cytometric analysis involving sialic acid-specific lectins, and a concomitant increase of free sialic acid was observed in the supernatant. A cell adhesion assay showed that the HX/XO treatment of HL60 cells decreases their capability of binding to human umbilical vein endothelial cells (HUVEC), probably because of an impairment of the interaction involving E-selectin, whereas the decrease in the binding was canceled by the addition of superoxide dismutase (SOD) and catalase. In fact, cell surface sialyl lewis x (sLex), but not lewis x (Lex), was decreased by HX/XO treatment. Thus, it is more likely that the impaired interaction is based on diminished levels of the selectin ligand. Cleavage of sialic acid by ROS was further verified by the degradation of 4MU-Neu5Ac by HX/XO in the presence of hydrogen peroxide and iron ion. These results indicate that glycosidic linkage of sialic acid is a potential target for superoxide and other related ROS. It is well known that ROS cause cellular damages such as lipid peroxidation and protein oxidation, but, as suggested by the findings reported in the literature, ROS may also regulate cell adhesion via the structural alteration of sialylated oligosaccharides on the cell surface.
Key words: cell adhesion / reactive oxygen species / selectin / sialic acid / sialyl lewis x