Related Experiment Videos
Tumor necrosis factor-induced apoptosis is mediated by a CrmA-sensitive cell death pathway
M Miura1, R M Friedlander, J Yuan
1Cardiovascular Research Center, Massachusetts General Hospital-East, Charlestown 02129, USA.
Abstract:
We report here that the activation of the interleukin 1 beta (IL-1 beta)-converting enzyme (ICE) family is likely to be one of the crucial events of tumor necrosis factor (TNF) cytotoxicity. The cowpox virus CrmA protein, a member of the serpin superfamily, inhibits the enzymatic activity of ICE and ICE-mediated apoptosis. HeLa cells overexpressing crmA are resistant to apoptosis induced by Ice but not by Ich-1, another member of the Ice/ced-3 family of genes. We found that the CrmA-expressing HeLa cells are resistant to TNF-alpha/cycloheximide (CHX)-induced apoptosis. Induction of apoptosis in HeLa cells by TNF-alpha/CHX is associated with secretion of mature IL-1 beta, suggesting that an IL-1 beta-processing enzyme, most likely ICE itself, is activated by TNF-alpha/CHX stimulation. These results suggest that one or more members of the ICE family sensitive to CrmA inhibition are activated and play a critical role in apoptosis induced by TNF.
Insights
Tumor necrosis factor (TNF) triggers cell death by activating the interleukin-1 beta-converting enzyme (ICE) family. Cowpox virus CrmA protein blocks ICE, preventing TNF-induced apoptosis in cells.
Area of Science:
- Cell biology
- Molecular biology
- Immunology
Background:
- Tumor necrosis factor (TNF) induces apoptosis, a crucial process in cellular regulation and disease.
- The precise molecular mechanisms underlying TNF-induced apoptosis are complex and involve multiple signaling pathways.
- Interleukin-1 beta-converting enzyme (ICE) family proteases are known regulators of apoptosis.
Purpose of the Study:
- To investigate the role of the ICE family in TNF-induced cytotoxicity.
- To determine if the cowpox virus CrmA protein, an ICE inhibitor, can block TNF-induced apoptosis.
- To elucidate the specific ICE family members involved in TNF signaling.
Main Methods:
- Utilizing HeLa cells overexpressing the CrmA protein.
- Inducing apoptosis using TNF-alpha/cycloheximide (CHX) and other stimuli.
- Assessing cellular resistance to apoptosis.
- Measuring the secretion of mature IL-1 beta.
Main Results:
- HeLa cells overexpressing CrmA exhibited resistance to TNF-alpha/CHX-induced apoptosis.
- CrmA expression conferred resistance to apoptosis induced by ICE but not Ich-1.
- TNF-alpha/CHX stimulation led to the secretion of mature IL-1 beta, indicating activation of an IL-1 beta-processing enzyme.
- These findings suggest that CrmA-sensitive ICE family members are activated by TNF-alpha/CHX.
Conclusions:
- Activation of CrmA-sensitive ICE family proteases is a critical event in TNF-induced apoptosis.
- The cowpox virus CrmA protein effectively inhibits TNF-induced cell death by targeting specific ICE family members.
- This study highlights the involvement of the IL-1 beta-processing pathway in TNF cytotoxicity.