REGULATION OF INTERCELLULAR-ADHESION MOLECULE-1 GENE BY TUMOR-NECROSIS-FACTOR-ALPHA IS MEDIATED BY THE NUCLEAR FACTOR-KAPPA-B HETERODIMERS P65 P65 AND P65/C-REL IN THE ABSENCE OF P50/
F. Aoudjit et al., REGULATION OF INTERCELLULAR-ADHESION MOLECULE-1 GENE BY TUMOR-NECROSIS-FACTOR-ALPHA IS MEDIATED BY THE NUCLEAR FACTOR-KAPPA-B HETERODIMERS P65 P65 AND P65/C-REL IN THE ABSENCE OF P50/, Cell growth & differentiation, 8(3), 1997, pp. 335-342
Human intercellular adhesion molecule-1 (ICAM-1) plays an important ro
le in immune responses as the major specific ligand for the beta 2-int
egrins LFA-1 and Mac-1. During the inflammatory process, ICAM-1 expres
sion is stimulated by various proinflammatory cytokines, We have exami
ned the mechanisms of transcriptional control involved in the stimulat
ion of ICAM-1 gene expression by tumor necrosis factor-alpha (TNF-alph
a) and by the nuclear factor-kappa B (NF-kappa B) family of transcript
ion factors in the Ad5-transformed human embryonal kidney cell line 29
3. A proximal site (5'-TTGGAAATTCC-3') mapping at position -228 from t
he ATG and known to mediate TNF-alpha responsiveness in endothelial ce
lls is also critical for TNF-alpha responsiveness in 293 cells. Howeve
r, unlike endothelial cells, electrophoretic mobility shift assays, us
ing whole-cell extracts prepared from TNF-alpha-treated cells, showed
that TNF-alpha induces the formation of a specific kappa B binding com
plex, mainly composed of NF-kappa B subunits RelA and c-Rel. Electroph
oretic mobility shift assays done with 293 cells transfected with p50,
p65, or both subunits showed that p50 only has a weak ability to bind
the proximal ICAM-1 NF-kappa B site, Another element exhibiting seque
nce homology with NF-kappa B binding sites and located at position -54
0 relative to the mRNA cap site was found to be involved in the basal
activity of the ICAM-1 promoter, is not required for TNF-alpha respons
iveness, and does not bind NF-kappa B subunits. Whereas transactivatio
n of the ICAM-1 promoter by p65 requires the proximal NF-kappa B site,
deletion mutant analysis showed that p50 and, to a greater extent, p5
2 transactivate reporter plasmids lacking NF-kappa B sites, suggesting
the presence of other p50/p52 responsive element(s).