Ceramide-induced nuclear translocation of NF-kappa B is a potential mediator of the apoptotic response to TNF-alpha in murine clonal osteoblasts.
Osteoblasts are affected by TNF-alpha overproduction by immune cells during inflammation. We demonstrate that apoptosis is induced in murine osteoblastic MC3T3-E1 cells by exceeding the concentrations 100 units/mL of TNF-alpha and 10 mumol/L of synthetic ceramide. The apoptotic signaling pathway activated by TNF-alpha was examined in MC3T3-E1 cells. Endogenous cellular ceramide concentrations increased within 3 min, and comparable peak levels were observed for 30 min after TNF-alpha treatment. Activation of nuclear factor-kappa B (NF-kappa B) was detected after TNF-alpha or synthetic ceramide stimulation. The concentration of NF-kappa B increased in the perinuclear region after 5 min of treatment and translocation into the nucleus was observed within 15 min of treatment. Degradation of I kappa B alpha/MAD-3 was observed after 60 min of ceramide treatment. These results indicate that nuclear translocation and activation of NF-kappa B through TNF-alpha generated ceramide may be one important apoptotic signaling pathway in MC3T3-E1 cells. The osteoblastic apoptosis triggered by TNF-alpha-generated ceramide may explain the inhibition of bone formation during severe bone inflammation.
Kitajima
I
I
Department of Laboratory Medicine, Faculty of Medicine, University of Kagoshima, Japan.
Soejima
Y
Y
Takasaki
I
I
Beppu
H
H
Tokioka
T
T
Maruyama
I
I
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002467:Cell Nucleus / Q000187:drug effects* / Q000378:metabolism; D002518:Ceramides / Q000494:pharmacology*; D002999:Clone Cells / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000378:metabolism; D020672:I-kappa B Proteins; D051379:Mice; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D011994:Recombinant Proteins / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D002518:Ceramides; D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha