A functional role of I kappa B-epsilon in endothelial cell activation.
The NF-kappa B inhibitor I kappa B-epsilon is a new member of the I kappa B protein family, but its functional role in regulating NF-kappa B-mediated induction of adhesion molecule expression is unknown. In vascular endothelial cells, I kappa B-epsilon associates predominantly with the NF-kappa B subunit Rel A and to a lesser extent with c-Rel, whereas I kappa B-alpha and I kappa B-beta associate with Rel A only. Following stimulation with TNF-alpha, pyrrolidine dithiocarbamate (PDTC), N-acetylcysteine, and dexamethasone prevented I kappa B kinase-induced I kappa B-alpha, but not I kappa B-beta or I kappa B-epsilon phosphorylation and degradation. Since the activation of NF-kappa B is required for the induction of adhesion molecule expression, we examined the role of I kappa B-epsilon in the transactivation of promoters from VCAM-1, ICAM-1, and E-selectin. Using reporter gene constructs of adhesion molecule promoters, PDTC inhibited VCAM-1 and E-selectin, but to a lesser extent, ICAM-1 promoter activity. Subcloning of kappa B cis-acting elements of VCAM-1, E-selectin, and ICAM-1 into a heterologous promoter construct revealed that PDTC inhibited VCAM-1 and E-selectin, but to a lesser extent, ICAM-1 kappa B promoter activity. By electrophoretic mobility shift assay, NF-kappa B heterodimers containing c-Rel specifically bind to the kappa B motif in the ICAM-1, but not VCAM-1 or E-selectin promoter. Indeed, overexpression of c-Rel induced ICAM-1 kappa B promoter activity to a greater extent than that of E-selectin and overexpression of I kappa B-epsilon inhibited ICAM-1 and VCAM-1 promoter activity in endothelial cells. These findings indicate that c-Rel-associated I kappa B-epsilon is involved in the induction of ICAM-1 expression.
Spiecker
M
M
Vascular Medicine and Atherosclerosis Unit, Cardiovascular Division, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
Darius
H
H
Liao
J K
JK
D000818:Animals; D002417:Cattle; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology* / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D020672:I-kappa B Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology; D007700:Kinetics; D016328:NF-kappa B / Q000502:physiology; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000276:immunology; D011518:Proto-Oncogene Proteins / Q000502:physiology*
D015815:Cell Adhesion Molecules; D020672:I-kappa B Proteins; D016328:NF-kappa B; C105627:NFKBIE protein, human; D011518:Proto-Oncogene Proteins