V. Volloch et al., ATPase activity of the heat shock protein Hsp72 is dispensable for its effects on dephosphorylation of stress kinase JNK and on heat-induced apoptosis, FEBS LETTER, 461(1-2), 1999, pp. 73-76
ri major inducible heat shock protein, Hsp72, has previously been found to
stimulate dephosphorylation (inactivation) of stress kinase JNK in heat-sho
cked cells and protect them from apoptasis, Using Rat-1 fibroblasts with co
nstitutive expression of a human Hsp72 or its deletion mutant lacking an AT
Pase domain (C-terminal fragment (CTF)), me tested whether ATPase activity
of Hsp72 is necessary for these effects. We found that expression of CTF ma
rkedly increased, similarly to the intact protein, JNK dephosphorylation in
heat-shocked cells, As a result, JNK inactivation following heat shock occ
urred much faster in cells expressing either full-length or mutant Hsp72 th
an in parental cells and this,vas accompanied by suppression of heat-induce
d apoptosis, Thus, protein refolding activity of Hsp72 appears to he dispen
sable for its effect on JNK inactivation and apoptosis. (C) 1999 Federation
of European Biochemical Societies.