Related Experiment Videos
TRAIL-induced apoptosis in U-1242 MG glioma cells
H E Saqr1, O M Omran, J L Oblinger
1Department of Pathology, The Ohio State University, 4166 Graves Hall, 333 W. 10th Avenue, Columbus, OH 43210, USA.
Abstract:
Tumor necrosis factor related apoptosis-inducing ligand (TRAIL) induces apoptosis in U-1242 MG cells. To investigate the molecular events involved in this process, we studied the effects of TRAIL on the localization within membrane fractions of molecules critical to the extrinsic apoptotic pathway. We report here that death receptor-5 (DR5), tumor necrosis factor receptor-1 (TNF-R1), and Fas receptor (FasR) are all located in the caveolin-1-enriched membrane fractions, and TRAIL caused the translocation of DR5, FasR, and TNF-R1 to the caveolar fractions. Caspase-8 is mainly located outside of caveolae, but TRAIL caused it to redistribute to the caveolin-1-enriched fractions where it was cleaved. Within 6 hours, the cleaved caspase-8 appeared in the high-density, noncaveolin fractions. Using confocal microscopy, we found that DR5, caspase-8, and caveolin-1 became progressively concentrated in blebs of plasmalemma as they formed in response to TRAIL. Our results provide the first evidence for the caveolar localization of TNF-R1 and DR5 and the coordinated redistribution among membrane fractions of several death receptors in response to TRAIL. We propose that the coordinated movement of these molecules among membrane compartments is probably an important component of the mechanisms regulating and initiating the extrinsic apoptotic pathway in human glioma cells.
Insights
Tumor necrosis factor related apoptosis-inducing ligand (TRAIL) triggers cell death in glioma cells. TRAIL causes key apoptotic molecules to move into specific cell membrane compartments, initiating programmed cell death.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Tumor necrosis factor related apoptosis-inducing ligand (TRAIL) is a critical mediator of the extrinsic apoptotic pathway.
- Understanding the precise molecular mechanisms of TRAIL-induced apoptosis is essential for developing targeted cancer therapies.
- Caveolae, specialized membrane microdomains, are increasingly recognized for their role in signal transduction.
Purpose of the Study:
- To investigate the role of caveolin-1-enriched membrane fractions in TRAIL-induced apoptosis.
- To determine the localization and redistribution of death receptors and caspases upon TRAIL stimulation in human glioma cells.
- To elucidate the spatial dynamics of molecules involved in the extrinsic apoptotic pathway within membrane compartments.
Main Methods:
- Fractionation of U-1242 MG cell membranes to isolate caveolin-1-enriched and non-caveolin fractions.
- Western blotting and confocal microscopy to analyze the localization and translocation of death receptors (DR5, TNF-R1, FasR) and caspase-8.
- Time-course analysis of molecular redistribution and caspase cleavage following TRAIL treatment.
Main Results:
- Death receptors (DR5, TNF-R1, FasR) and caveolin-1 are co-localized in specific membrane fractions.
- TRAIL stimulation induces the translocation of DR5, FasR, and TNF-R1 into caveolar fractions.
- TRAIL causes caspase-8 redistribution to caveolin-1-enriched fractions, leading to its cleavage and subsequent appearance in non-caveolar fractions.
- Confocal microscopy revealed the concentration of DR5, caspase-8, and caveolin-1 in plasma membrane blebs during TRAIL-induced apoptosis.
Conclusions:
- This study provides the first evidence for the caveolar localization of TNF-R1 and DR5.
- TRAIL induces a coordinated redistribution of death receptors and caspase-8 among membrane compartments in human glioma cells.
- The movement of these molecules within membrane fractions is a crucial mechanism regulating the initiation of the extrinsic apoptotic pathway.
