Regulatory role of ceramide in interleukin (IL)-1 beta-induced E-selectin expression in human umbilical vein endothelial cells. Ceramide enhances IL-1 beta action, but is not sufficient for E-selectin expression.
Recent studies indicate that sphingolipids mediate several cellular processes. We assessed roles of sphingolipids in the regulation of E-selectin expression in human umbilical vein endothelial cells. All exogenously-added sphingolipids (sphingosine, C2-ceramide, sphingosine 1-phosphate, and N,N-dimethylsphingosine) failed to induce E-selectin expression by themselves. C2-ceramide at 5 micron enhanced interleukin-1 beta (IL-1 beta)-induced E-selectin expression 2.7-fold, whereas other sphingolipids tested had no effects on this process. Sphingomyelinase, but not phospholipases A2, C, or D, mimicked the enhancing effect of C2-ceramide. Northern blot analyses revealed that C2-ceramide and sphingomyelinase increased interleukin-1 beta-induced E-selectin gene transcription levels. C2-ceramide and sphingomyelinase induced NF-kappaB activation by themselves and enhanced activation by IL-1 beta, which is essential for E-selectin expression. Immunological analyses with anti-NF-kappaB antibodies showed that subunit composition of NF-kappaB activated by IL-1 beta differs from that activated by C2-ceramide, suggesting that signaling pathways utilized by these stimuli may be different. Treatment with C2-ceramide or sphingomyelinase did not alter NF-ELAM1 specific binding activity. IL-1 beta induced sphingomyelin hydrolysis to ceramide; intracellular ceramide level increased to 182% of control value at 30 min. Taken together, these findings suggest that (i) sphingomyelin hydrolysis to ceramide does not trigger, but rather enhances cytokine-induced E-selectin expression, in part through NF-kappaB; (ii) sphingomyelin hydrolysis to ceramide does not mediate all the effects of IL-1 beta, although it may play important roles in IL-1 beta signal transduction in human umbilical vein endothelial cells.
Masamune
A
A
Biomembrane Institute, Seattle, Washington 98119, USA.
Igarashi
Y
Y
Hakomori
S
S
D001483:Base Sequence; D002478:Cells, Cultured; D002518:Ceramides / Q000378:metabolism / Q000502:physiology; D004357:Drug Synergism; D019040:E-Selectin / Q000096:biosynthesis*; D004730:Endothelium, Vascular / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D007700:Kinetics; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D010740:Phospholipases / Q000494:pharmacology; D011994:Recombinant Proteins / Q000494:pharmacology; D013107:Sphingolipids / Q000494:pharmacology* / Q000502:physiology*; D013329:Structure-Activity Relationship; D014158:Transcription, Genetic / Q000187:drug effects; D014471:Umbilical Veins
D002518:Ceramides; D019040:E-Selectin; D007375:Interleukin-1; D015345:Oligonucleotide Probes; D011994:Recombinant Proteins; D013107:Sphingolipids; D010740:Phospholipases