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Cytoskeletal disruption induces T cell apoptosis by a caspase-3 mediated mechanism
1Transplantation and Immunobiology Group, The John P. Robarts Research Institute, London, Ontario, Canada.
Abstract:
T cell apoptosis can be triggered by different mechanisms that lead to distinctive features such as cell shrinkage, membrane blebbing, phosphatidylserine externalization, and internucleosomal DNA fragmentation. Prevailing models for the induction of apoptosis place the cytoskeleton as a distal target of the death effector molecules ('executioners'). However, the cytoskeleton can also play a role in the induction of apoptosis as suggested by the finding that cytoskeletal disruption can induce apoptosis. The mechanism by which this occurs is unknown. Here, we report that T cell apoptosis by cytoskeletal disruption involves a protein synthesis-independent mechanism leading to up-regulation of caspase-3 protease activity and increased accessibility of active caspase-3 to its substrate. Thus, cytoskeleton integrity may regulate the subcellular compartmentalization of death effector molecules.
Insights
Cytoskeletal disruption triggers T cell apoptosis via a protein synthesis-independent pathway, increasing caspase-3 activity. This suggests cytoskeleton integrity regulates the localization of cell death molecules.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- T cell apoptosis involves distinct cellular changes like shrinkage and DNA fragmentation.
- Current models consider the cytoskeleton a downstream target of apoptosis-inducing molecules.
- Evidence suggests cytoskeletal disruption itself can initiate apoptosis, but the mechanism remains unclear.
Purpose of the Study:
- To elucidate the mechanism by which cytoskeletal disruption induces T cell apoptosis.
- To investigate the role of protein synthesis and caspase activity in this process.
- To determine if cytoskeleton integrity influences the subcellular distribution of apoptotic effectors.
Main Methods:
- Induction of T cell apoptosis through cytoskeletal disruption.
- Analysis of protein synthesis dependency.
- Assay of caspase-3 protease activity.
- Assessment of caspase-3 substrate accessibility.
Main Results:
- Cytoskeletal disruption induces T cell apoptosis through a mechanism independent of protein synthesis.
- This process leads to the upregulation of caspase-3 protease activity.
- Increased accessibility of active caspase-3 to its substrates was observed.
Conclusions:
- Cytoskeleton integrity plays a crucial role in regulating T cell apoptosis.
- The mechanism involves enhanced caspase-3 activation and accessibility.
- Cytoskeleton may control the subcellular localization of death effector molecules, influencing apoptosis induction.