Interferon-gamma enhancement of E-selectin expression on endothelial cells is inhibited by monensin.
The expression of E-selectin reaches a maximum 4-6 h after stimulation of human umbilical vein endothelial cells (HUVEC) in vitro with tumour necrosis factor-alpha (TNF-alpha) and then declines to basal level within 24 h. If interferon-gamma (IFN-gamma) is added to the cell culture medium together with TNF-alpha the surface expression of E-selectin is augmented and prolonged in a synergistic way. The aim of the present study was to investigate if altered protein glycosylation could explain the IFN-gamma induced persistent surface expression of E-selectin. SDS-PAGE analysis of HUVEC glycoproteins, metabolically radiolabelled in the carbohydrate portion, indicated that addition of IFN-gamma produced an altered protein glycosylation. Lectin blot analysis using the Sambucus nigra agglutinin lectin also indicated differences in protein glycosylation when HUVEC were incubated with IFN-gamma/TNF-alpha compared to TNF-alpha alone. The kinetics of surface expression of E-selectin were measured using a cell ELISA assay. When HUVEC were incubated with monesin, a potent inhibitor of late Golgi function, together with both TNF-alpha and IFN-gamma, the additive effect of IFN-gamma on E-selectin expression was almost abolished. Since monensin is known to affect glycosylation processing, this experiment suggested that the IFN-gamma induced change in protein glycosylation might induce the prolonged surface expression of E-selectin. However, when HUVEC were cultured with IFN-gamma/TNF-alpha in the presence of several different inhibitors of N-glycosylation processing, no significant effect of E-selectin expression was observed. Regulation of adhesion molecule expression after activation of endothelial cells is likely to play a pivotal role for the inflammatory response. Further studies are needed to understand the mechanisms underlying this regulation.
Strindhall
J
J
Department of Clinical Chemistry, Faculty of Health Sciences, University Hospital, Linköping, Sweden.
Lundblad
A
A
Påhlsson
P
P
D017485:1-Deoxynojirimycin / Q000494:pharmacology; D000276:Adjuvants, Immunologic / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D019040:E-Selectin / Q000096:biosynthesis* / Q000187:drug effects; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D006031:Glycosylation / Q000187:drug effects; D006801:Humans; D007212:Indolizines / Q000494:pharmacology; D007371:Interferon-gamma / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D008985:Monensin / Q000494:pharmacology*; D011506:Proteins / Q000187:drug effects / Q000378:metabolism; D017026:Swainsonine / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014471:Umbilical Veins; D054836:Indolizidines
D017485:1-Deoxynojirimycin; D000276:Adjuvants, Immunologic; D019040:E-Selectin; D007212:Indolizines; D007371:Interferon-gamma; D008985:Monensin; D011506:Proteins; D017026:Swainsonine; D014409:Tumor Necrosis Factor-alpha; C037806:castanospermine; D054836:Indolizidines