Sy. Na et al., I-KAPPA-B-BETA INTERACTS WITH THE RETINOID-X-RECEPTOR AND INHIBITS RETINOID-DEPENDENT TRANSACTIVATION IN LIPOPOLYSACCHARIDE-TREATED CELLS, The Journal of biological chemistry, 273(6), 1998, pp. 3212-3215
To elucidate the molecular action of the NF kappa B inhibitor I kappa
B beta, we isolated a number of I kappa B beta interactors using the y
east two-hybrid system, These include the retinoid X receptor (RXR), w
hose interaction with I kappa B beta is significantly stimulated by th
e RXR ligand g-cis-retinoic acid, as shown in the yeast system as well
as the glutathione S-transferase pull down assays. RXR is a nuclear p
rotein, whereas I kappa B beta accumulates in the nucleus only in cell
s stimulated with lipopolysaccharide or other inducers that result in
prolonged activation of NF kappa beta. Consistent with this, cotransfe
ction with I kappa B beta specifically repressed the 9-cis-RA-induced
transcriptional activities of RXR in an lipopolysaccharide-dependent m
anner. These results suggest a novel I kappa B beta-mediated antagonis
m between the signaling pathways of NF kappa B and RXR.