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Raf‐independent and MEKK1‐dependent activation of NF‐κB by hydrogen peroxide in 70Z/3 pre‐B lymphocyte tumor cells
Author(s) -
Lee Michael,
Koh Woo Suk
Publication year - 2003
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.10376
Subject(s) - kinase , activator (genetics) , microbiology and biotechnology , phosphorylation , iκbα , signal transduction , nf κb , chemistry , c jun , iκb kinase , biology , biochemistry , transcription factor , receptor , gene
We have previously demonstrated that hydrogen peroxide (H 2 O 2 ) treatment of murine 70Z/3 pre‐B lymphocytes inhibits the immune response to lipopolysaccharide by attenuating signaling through c‐Jun N‐terminal kinase (JNK) activation. In the present study, we further examined the signaling intermediates responsible for immunosuppression by H 2 O 2 , focusing on NF‐κB, a dimeric transcription factor whose activation is implicated in a number of immune response. Treatment of 70Z/3 pre‐B cells with H 2 O 2 caused activation of NF‐κB in the nuclei by detection of NF‐κB specific DNA binding, concomitant with phosphorylation of IκBα. H 2 O 2 stimulation of NF‐κB occurred within 20 min of treatment, reached maximum level at 60 min, and sustained for 2 h or more. Especially, MEK1 may contribute to H 2 O 2 ‐induced NF‐κB activation as shown in the inhibition of NF‐κB binding activity by the MEK1 inhibitor, PD 98059, and H 2 O 2 ‐induced MEK1 activation. However, H 2 O 2 exhibited no effect on the activity of Raf‐1 kinase, which was an upstream activator of MEK1. Furthermore, B‐58l and α‐hydroxyfarnesylphosphonic acid, two inhibitors of Ras, did not block NF‐κB activation. In addition, the transient transfection of a dominant negative Ras (RasN17) construct showed a negligible inhibitory effect on the activation of NF‐κB by H 2 O 2 . Instead, treatment of 70Z/3 cells with H 2 O 2 resulted in the activation of MAPK kinase kinase 1 (MEKK1) as well as JNK. Therefore, our data suggest that H 2 O 2 regulates the activity of NF‐κB by MEK1 activation through MEKK1‐dependent but Ras/Raf‐independent mechanism. © 2002 Wiley‐Liss, Inc.