Hypoxia/reoxygenation stimulates Ca2+-dependent ICAM-1 mRNA expression in human aortic endothelial cells.
Increased endothelial ICAM-1 expression is found in normal aging and in atherosclerosis and is related to the chronic effects of oxidative stress. We examined the Ca(2+)-dependence of ICAM-1 mRNA expression in human aortic endothelial cells (HAEC) exposed to hypoxia/reoxygenation (H/R) as a model of oxidative stress. HAEC were exposed to glucose-free hypoxia (95% N(2)/5% CO(2)) for 60 min and were then reoxygenated (21% O(2)/5% CO(2)) and observed for up to 6h. Reactive oxygen species (ROS) generation was measured by dichlorofluorescein fluorescence and ICAM-1 mRNA was assessed by Northern blot. Upon reoxygenation after hypoxia, ROS production occurred in HAEC and was inhibited by diphenyleneiodonium and by polyethylene glycol-catalase, suggesting the involvement of NADPH oxidase-derived hydrogen peroxide. Hypoxia alone did not increase either ROS production or ICAM-1 mRNA levels, but a 2.5-fold increase in ICAM-1 mRNA was noted by 30 min of reoxygenation. This was not observed in Ca(2+)-free buffer or in cells treated with diphenyleneiodonium. Thus, H/R upregulates ICAM-1 mRNA in HAEC by a Ca(2+)- and ROS-dependent mechanism. Characterizing the signaling pathways involved in H/R-induced adhesion molecule expression may result in a better understanding of the vascular biology of normal aging and the pathobiology of atherosclerosis.
Johns Hopkins Bayview Medical Center, Johns Hopkins University School of Medicine, Baltimore, MD 21224-2780, USA.
Roy C
RC
Ziegelstein
Chaoxia
C
He
Qinghua
Q
Hu
D001011:Aorta / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D015687:Cell Hypoxia / Q000502:physiology*; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*
D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D018799:Intercellular Adhesion Molecule-1; D010100:Oxygen; D002118:Calcium