title: Lactosylceramide mediates shear-induced endothelial superoxide production and intercellular adhesion molecule-1 expression.
abstract: Laminar shear stress activates NADPH oxidase in vascular endothelial cells (ECs), and the generated superoxide radicals (O2(-.) are known to be involved in intercellular adhesion molecule (ICAM)-1 expression. In this study, the role of a glycosphingolipid (GSL), lactosylceramide (LacCer), as a second messenger in the shear-induced O2(-.) generation and ICAM-1 expression was examined. It is known that glucosylceramide synthase (GlcT-1) catalyzes the synthesis of glucosylceramide (GlcCer) from ceramide, and subsequently lactosylceramide synthase (GalT-2) synthesizes LacCer from GlcCer. We observed that exposing cultured human umbilical vein ECs (HUVECs) to fluid shear stress (20 dyn/cm(2) for 30 min) activated GalT-2. Shear stress also increased EC O2(-.) generation, that peaked at 30 min, and surface ICAM-1 protein expression at 6 h post-shear. EC preincubation with the antioxidant N-acetylcysteine (NAC; 20 mM for 2 h) completely abolished the shear-induced O2(-.) production and significantly inhibited ICAM-1 expression. EC preincubation with D-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (D-PDMP), an inhibitor of the GSL glycosyltransferases GlcT-1 and GalT-2, abrogated the shear-induced activation of GalT-2. D-PDMP also abolished the shear-induced O2(-.) production and ICAM-1 expression. We conclude that laminar shear stress activates GalT-2 to produce LacCer. In turn, LacCer activates NADPH oxidase, which produces O2(-.), and O2(-.) mediates the shear-induced increase in ICAM-1 expression. Thus, LacCer may play an important role in hemodynamic force-induced pathological conditions, such as atherosclerosis and ischemia/reperfusion injury.
authors.affiliation: Vascular Bioengineering Laboratory, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: L H
authors.initials: LH
authors.lastname: Yeh
authors.forename: A M
authors.initials: AM
authors.lastname: Kinsey
authors.forename: S
authors.initials: S
authors.lastname: Chatterjee
authors.forename: B R
authors.initials: BR
authors.lastname: Alevriadou
mesh_terms: D015703:Antigens, CD; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005700:Galactosyltransferases / Q000378:metabolism; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D007790:Lactosylceramides / Q000494:pharmacology*; D009025:Morpholines / Q000494:pharmacology; D013314:Stress, Mechanical; D013481:Superoxides / Q000378:metabolism*
chemical_list: D015703:Antigens, CD; D004791:Enzyme Inhibitors; D007790:Lactosylceramides; D009025:Morpholines; D013481:Superoxides; D018799:Intercellular Adhesion Molecule-1; C009744:CDw17 antigen; C033110:RV 538; D005700:Galactosyltransferases; C023235:glucosylceramide beta-1-4-galactosyltransferase