Related Experiment Videos
TNF-alpha-mediated apoptosis in chondrocytes sensitized by MG132 or actinomycin D
1Department of Internal Medicine, Hallym University College of Medicine, 1 Okchon-Dong, Chunchon, Kangwon-Do, Republic of Korea.
Abstract:
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.
Insights
Tumor necrosis factor-alpha (TNF-alpha) triggers cartilage cell death via different pathways when treated with actinomycin D or MG132. These agents differentially affect apoptosis-related proteins and NF-kappaB activation in chondrocytes.
Area of Science:
- Biochemistry
- Cell Biology
- Immunology
Background:
- Chondrocyte apoptosis contributes to osteoarthritis (OA) pathogenesis.
- Tumor necrosis factor-alpha (TNF-alpha) is implicated in OA-related cartilage degradation.
Purpose of the Study:
- To investigate the distinct mechanisms of TNF-alpha-induced chondrocyte apoptosis using actinomycin D and MG132.
- To analyze the differential effects of these agents on apoptosis-related signaling pathways.
Main Methods:
- Primary human OA chondrocytes were treated with TNF-alpha combined with either actinomycin D or MG132.
- Analysis included apoptosis-related protein expression, NF-kappaB activation, and IkappaB degradation.
- Caspase inhibition was used to assess apoptosis pathways.
Main Results:
- Both actinomycin D and MG132 enhanced TNF-alpha-induced chondrocyte death.
- MG132-potentiated apoptosis was more sensitive to caspase inhibition than actinomycin D-induced apoptosis.
- MG132, unlike actinomycin D, inhibited TNF-alpha-induced IkappaB degradation and NF-kappaB activation.
- Both agents increased p53 levels, but only MG132 upregulated p53 response proteins.
Conclusions:
- Actinomycin D and MG132 modulate TNF-alpha-mediated chondrocyte apoptosis through distinct molecular mechanisms.
- These findings highlight differential impacts on NF-kappaB signaling and p53 pathway activation.