Eguchi Hironobu, Ikeda Yoshitaka, Ookawara Tomomi, Koyota Souichi, Fujiwara Noriko, Honke Koichi, Wang Peng G, Taniguchi Naoyuki, Suzuki Keiichiro
Department of Biochemistry, Hyogo College of Medicine, 1-1 Mukogawa, Nishinomiya, Hyogo 663-8501, Japan.
Glycobiology. 2005 Nov;15(11):1094-101. doi: 10.1093/glycob/cwj003. Epub 2005 Jul 6.
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 (sLe x), but not lewis x (Le x), 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.
研究了活性氧（ROS）对细胞表面寡糖的修饰作用以及这种修饰对细胞黏附的生物学效应。用次黄嘌呤和黄嘌呤氧化酶（HX/XO）组合产生的ROS处理人早幼粒细胞白血病细胞系HL60，通过涉及唾液酸特异性凝集素的流式细胞术分析表明，细胞表面唾液酸含量降低，同时在上清液中观察到游离唾液酸增加。细胞黏附试验表明，HX/XO处理HL60细胞会降低其与人脐静脉内皮细胞（HUVEC）结合的能力，这可能是由于涉及E-选择素的相互作用受损，而添加超氧化物歧化酶（SOD）和过氧化氢酶可消除这种结合能力的降低。事实上，HX/XO处理会降低细胞表面唾液酸化路易斯x（sLe x）的含量，但不会降低路易斯x（Le x）的含量。因此，更有可能的是，受损的相互作用是基于选择素配体水平的降低。在过氧化氢和铁离子存在的情况下，HX/XO对4MU-Neu5Ac的降解进一步证实了ROS对唾液酸的切割作用。这些结果表明，唾液酸的糖苷键是超氧化物和其他相关ROS的潜在作用靶点。众所周知，ROS会导致细胞损伤，如脂质过氧化和蛋白质氧化，但正如文献报道的研究结果所表明的，ROS也可能通过细胞表面唾液酸化寡糖的结构改变来调节细胞黏附。
