Transient nuclear factor kappa B (NF-kappa B) activation stimulated by interleukin-1 beta may be partly dependent on proteasome activity, but not phosphorylation and ubiquitination of the I kappa B alpha molecule, in C6 glioma cells - Regulation of NF-kappa B linked to chemokine production
T. Uehara et al., Transient nuclear factor kappa B (NF-kappa B) activation stimulated by interleukin-1 beta may be partly dependent on proteasome activity, but not phosphorylation and ubiquitination of the I kappa B alpha molecule, in C6 glioma cells - Regulation of NF-kappa B linked to chemokine production, J BIOL CHEM, 274(22), 1999, pp. 15875-15882
We previously reported that several stresses can induce cytokine-induced ne
utrophil chemoattractant expression in a nuclear factor kappa B (NF-kappa B
)-dependent manner. In this study, we focused further on the regulation of
NF-kappa B, The activation of NF-kappa B and the subsequent cytokine-induce
d neutrophil chemoattractant induction in response to interleukin-1 beta (I
L-1 beta) were inhibited by proteasome inhibitors, MG132 and proteasome inh
ibitor I. Translocation of NF-kappa B into nuclei occurs by the phosphoryla
tion, multi-ubiquitination, and degradation of I kappa B alpha, a regulator
y protein of NF-kappa B, Nascent I kappa B alpha began to degrade 5 min aft
er treatment with IL-1 beta and disappeared completely after 15 min. Howeve
r, I kappa B alpha returned to basal levels after 45-60 min. Interestingly,
resynthesized I kappa B alpha was already phosphorylated at Ser-32, These
results suggest that 1) the upstream signals are still activated, although
the translocation of NF-kappa B peaks at 15 min; and 2) the regulated prote
in(s) acts downstream of I kappa B alpha phosphorylation, Western blotting
showed that the resynthesized and phosphorylated I kappa B molecules were a
lso upward-shifted by multi-ubiquitination in response to IL-1 beta treatme
nt. On the other hand, ATP-dependent Leu-Leu-Val-Tyr cleaving activity tran
siently increased, peaked at 15 min, and then decreased to basal levels at
60 min. Furthermore, the cytosolic fraction that was stimulated by IL-1 bet
a for 15 min, but not for 0 and 60 min, could degrade phosphorylated and mu
lti-ubiquitinated I kappa B alpha, These results indicate that the transien
t translocation of NF-kappa B in response to IL-1 beta may be partly depend
ent on transient proteasome activation.