Iv. Guzhova et al., MAJOR STRESS PROTEIN HSP70 INTERACTS WITH NF-KB REGULATORY COMPLEX INHUMAN T-LYMPHOMA CELLS, Cell stress & chaperones, 2(2), 1997, pp. 132-139
Polypeptides belonging to the Hsp70 major stress protein family and to
the NF-kB/Rel multi-functional regulatory complex are known to be inv
olved in cellular defense mechanisms. It was suggested that both syste
ms may interact in cells that respond to injuring stimuli. To check th
is, Molt4 human lymphoma cells were heated at 43 degrees C for 15 min
and, after a 6 h post-shock recovery period, the cells were activated
with phorbol ester or bacterial lipopolysaccharide. It was found that
mild heat shock caused a substantial increase of the intracellular Hsp
70 content with the concomitant suppression of NF-kB complexes, though
the latter was properly activated in non-stressed cells. After a 24 h
period of being inactive the complex fully recovered its activity and
p65 and c-Rel subunits migrated to the nucleus. This new active perio
d lasted even longer than that in non-heated control cells. As this su
ggested the existence of a Hsp70-related mechanism of NF-kB/Rel comple
x retention in cytoplasm, we carried out immunoprecipitation with the
use of anti-Hsp70 and anti-Rel antibodies. All three Rel family member
s p65, c-Rel, p50, but not their precursors and lkB alpha inhibitory p
rotein were shown to co-precipitate with the stress protein and anti-H
sp70 antibodies from both heated and non-heated cells. We conclude tha
t the Hsp70 stress protein may confer a new mechanism of NF-kB regulat
ion in cells affected by elevated temperature or other factors related
to the cellular response to stress.