V. Hietakangas et al., Activation of the MKK4-JNK pathway during erythroid differentiation of K562 cells is inhibited by the heat shock factor 2-beta isoform, FEBS LETTER, 505(1), 2001, pp. 168-172
In this study we report the activation of e-Jun terminal kinase (JNK) in hu
man K562 erythroleukemia cells undergoing hemin-mediated erythroid differen
tiation, which occurs concomitantly with activation of heat shock factor 2
(HSF2) and leads to a simultaneous in vivo phosphorylation of c-Jun. The ac
tivation of JNK occurs through activation of mitogen-activated protein kina
se kinase (MKK) 4 and not by activation of MKK7 or inhibition of JNK-direct
ed phosphatases. We have previously shown that overexpression of the HSF2-b
eta isoform inhibits the activation of HSF2 upon hemin-induced erythroid di
fferentiation. Here we demonstrate that HSF2-beta overexpression blocks the
hemin-induced activation of the MKK4-JNK pathway, suggesting an erythroid
lineage-specific JNK activation likely to be regulated by HSF2. (C) 2001 Fe
deration of European Biochemical Societies. Published by Elsevier Science B
.V. All rights reserved.