Activation of nuclear factor-kappaB by lipopolysaccharide in mononuclear leukocytes is prevented by inhibitors of cytosolic phospholipase A2.
In monocytes, lipopolysaccharide induces synthesis and activity of the 85-kDa cytosolic phospholipase A2. This enzyme releases arachidonic acid and lyso-phospholipids from membranes which are metabolized to eicosanoids and platelet-activating-factor. These lipid mediators increase activity of transcription factors and expression of cytokine genes indicating a function for cytosolic phospholipase A2 in signal transduction and inflammation. We have shown previously that trifluoromethylketone inhibitors of cytosolic phospholipase A2 suppressed interleukin-1beta protein and steady-state mRNA levels in human lipopolysaccharide-stimulated peripheral blood mononuclear leukocytes. In this study, the subcellular mechanisms were analyzed by which trifluoromethylketones interfere with gene expression. We found that they reduced the initial interleukin-1beta mRNA transcription rate through prevention of degradation of inhibitor-kappaB alpha. Consequently, cytosolic activation, nuclear translocation and DNA-binding of nuclear factor-kappaB were decreased. Trifluoromethylketones ameliorate chronic inflammation in vivo. Thus, this therapeutic potency may reside in retention of inactive nuclear factor-kappaB in the cytosol thereby abrogating interleukin-1beta gene transcription.
Burgermeister
E
E
Department of Molecular Pharmacology, Roche Diagnostics, Penzberg, Germany.
Tibes
U
U
Stockinger
H
H
Scheuer
W V
WV
D000818:Animals; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D015342:DNA Probes; D005434:Flow Cytometry; D006801:Humans; D006845:Hydrocarbons, Fluorinated / Q000494:pharmacology*; D007375:Interleukin-1 / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification; D007659:Ketones / Q000494:pharmacology*; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D010741:Phospholipases A / Q000037:antagonists & inhibitors* / Q000378:metabolism; D054467:Phospholipases A2; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000187:drug effects*
D015342:DNA Probes; D006845:Hydrocarbons, Fluorinated; D007375:Interleukin-1; D007659:Ketones; D008070:Lipopolysaccharides; D016328:NF-kappa B; D012333:RNA, Messenger; D010741:Phospholipases A; D054467:Phospholipases A2