Lj. Egan et al., Inhibition of interleukin-1-stimulated NF-kappa B RelA/p65 phosphorylationby mesalamine is accompanied by decreased transcriptional activity, J BIOL CHEM, 274(37), 1999, pp. 26448-26453
Nuclear factor kappa B (NF-kappa B) is an inducible transcription factor th
at regulates genes important in immunity and inflammation, The activity of
NF-kappa B is highly regulated: transcriptionally active NF-kappa B protein
s are sequestered in the cytoplasm by inhibitory proteins, I kappa B, A var
iety of extracellular signals, including interleukin-1 (IL-1), activate NF-
kappa B by inducing phosphorylation and degradation of I kappa B, allowing
nuclear translocation and DNA binding of NF-kappa B. Many of the stimuli th
at activate NF-kappa B by inducing I kappa B degradation also cause phospho
rylation of the NF-kappa B RelA (p65) polypeptide. The transactivating capa
city of RelA is positively regulated by phosphorylation, suggesting that in
addition to cytosolic sequestration by I kappa B, phosphorylation represen
ts another mechanism for control of NF-kappa B activity. In this report, we
demonstrate that mesalamine, an anti-inflammatory aminosalicylate, dose-de
pendently inhibits IL-1-stimulated NF-kappa B-dependent transcription witho
ut preventing I kappa B degradation or nuclear translocation and DNA bindin
g of the transcriptionally active NF-kappa B proteins, RelA, c-Rel, or RelB
. Mesalamine was found to inhibit IL-1-stimulated RelA phosphorylation. The
se data suggest that pharmacologic modulation of the phosphorylation status
of RelA regulates the transcriptional activity of NF-kappa B, independent
of nuclear translocation and DNA binding. These findings highlight the impo
rtance of inducible phosphorylation of RelA. in the control of NF-kappa B a
ctivity.