TNF-alpha-mediated apoptosis in chondrocytes sensitized by MG132 or actinomycin D.
The mechanism of TNF-alpha-mediated chondrocyte apoptosis in human articular cartilage was investigated. First passage OA chondrocytes were treated with actinomycin D or MG132 in combination with TNF-alpha to facilitate cell death. The patterns of apoptosis-related proteins, NF-kappaB activation, and IkappaB degradation were analyzed. Cell death was increased by 0.2 microg/ml of actinomycin D or 20 microM MG132 in combination with TNF-alpha. Apoptosis potentiated by MG132 was more effectively inhibited by caspase inhibitors than that by actinomycin D. MG132 or actinomycin D both led to a significant increase in p53, but the expressions of the p53 response proteins increased only in MG132 treated chondrocytes. TNF-alpha induced chondrocyte IkappaB phosphorylation was unaffected by either MG132 or actinomycin D. MG132, but not actinomycin D, inhibited the chondrocyte IkappaB degradation induced by TNF-alpha and NF-kappaB activation. Our results suggest that MG132 and actinomycin D exert different influences upon TNF-alpha-mediated chondrocyte apoptotic signaling.
A  Kim
Hyun
H
Department of Internal Medicine, Hallym University College of Medicine, 1 Okchon-Dong, Chunchon, Kangwon-Do, Republic of Korea.
W  Song
Yeong
Y
D000368:Aged; D000369:Aged, 80 and over; D017304:Annexin A5 / Q000494:pharmacology; D017209:Apoptosis; D015153:Blotting, Western; D061945:Caspase Inhibitors; D002467:Cell Nucleus / Q000378:metabolism; D019902:Chondrocytes / Q000378:metabolism* / Q000473:pathology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003609:Dactinomycin / Q000378:metabolism / Q000494:pharmacology*; D005434:Flow Cytometry; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D007976:Leupeptins / Q000494:pharmacology*; D008875:Middle Aged; D016328:NF-kappa B / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D017304:Annexin A5; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D020672:I-kappa B Proteins; D007976:Leupeptins; D016328:NF-kappa B; D011500:Protein Synthesis Inhibitors; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D016159:Tumor Suppressor Protein p53; D003609:Dactinomycin; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde