Related Experiment Videos
Ceramide enables fas to cap and kill
A Cremesti1, F Paris, H Grassmé
1Laboratory of Signal Transduction and Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
The Journal of Biological Chemistry
|April 5, 2001
Summary
Fas receptor capping, a process dependent on ceramide, is essential for optimal apoptosis signaling. This super-aggregation event requires intact membrane domains and is crucial for cell death induction.
Area of Science:
- Cell Biology
- Immunology
- Biochemistry
Background:
- Fas receptor (Fas) trimerization alone is insufficient for apoptosis induction.
- Super-aggregation of trimerized Fas into membrane caps is suggested as a prerequisite for apoptosis.
- Cell surface receptor capping involves lateral segregation and co-localization within the plasma membrane.
Purpose of the Study:
- To investigate the role of Fas receptor capping in apoptosis induction.
- To determine if ceramide generation is essential for Fas capping.
- To elucidate the mechanism by which Fas capping facilitates apoptosis.
Main Methods:
- Treatment of Jurkat T lymphocytes and primary hepatocytes with anti-Fas antibodies (CH-11, Jo2).
- Measurement of ceramide levels and detection of Fas receptor capping.
- Utilizing acid sphingomyelinase knockout hepatocytes and C(16)-ceramide supplementation.
- Employing FLAG-tagged soluble Fas ligand (sFasL) and cross-linking antibodies.
- Disruption of sphingolipid-enriched membrane domains using cholesterol-depleting agents.
Main Results:
- Ceramide elevation and Fas capping were detected rapidly after Fas ligation in both cell types.
- Acid sphingomyelinase knockout hepatocytes showed defects in ceramide generation, capping, and apoptosis, which were restored by C(16)-ceramide.
- Cross-linking of sFasL induced capping and apoptosis, and ceramide pretreatment enabled sFasL to cap and induce cell death.
- Disruption of membrane domains abrogated Fas capping and prevented apoptosis.
Conclusions:
- Fas receptor capping is a ceramide-dependent event essential for optimal Fas-mediated apoptosis.
- Ceramide generation is critical for the formation of Fas caps.
- Intact sphingolipid-enriched membrane domains are necessary for Fas capping and subsequent apoptosis.