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Interferons induce proteolytic degradation of TRAILR4
Andreas Wicovsky1, Daniela Siegmund, Harald Wajant
1Department of Molecular Internal Medicine, Medical Polyclinic, University of Würzburg, Röntgenring 11, 97070 Wurzburg, Germany.
Biochemical and Biophysical Research Communications
|September 28, 2005
Summary
Interferons like IFNgamma reduce TRAILR4 expression on target cells, enhancing apoptosis sensitivity. This suggests interferons promote cell death by down-regulating decoy receptors alongside increasing TRAIL in effector cells.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Interferon-gamma (IFNgamma) and Tumor Necrosis Factor (TNF)-related apoptosis inducing ligand (TRAIL) are key effector molecules in cytotoxic T lymphocytes (CTLs) and Natural Killer (NK) cells.
- TRAIL mediates apoptosis through its receptors, TRAILR2 and TRAILR4.
Purpose of the Study:
- To investigate the effect of interferons (IFNgamma and IFNalpha) on the expression of TRAIL receptors, specifically TRAILR4, TRAILR2, and CD95.
- To elucidate the mechanism of interferon-induced TRAILR4 down-regulation and its functional consequences on apoptosis.
Main Methods:
- Treatment of cells with IFNgamma and IFNalpha.
- Analysis of cell surface receptor expression using flow cytometry.
- Investigation of proteasomal involvement using protease inhibitors and MG132.
- Assessment of apoptosis sensitivity using siRNA-mediated knockdown of TRAILR4 and stimulation with TRAIL or CD95L.
Main Results:
- IFNgamma and IFNalpha significantly inhibit cell surface expression of TRAILR4.
- Interferon-induced TRAILR4 down-regulation is dependent on proteasomal activity.
- Inhibition of TRAILR4 sensitizes target cells to TRAIL-induced apoptosis but not CD95L-induced apoptosis.
Conclusions:
- Interferons reduce TRAILR4 expression on target cells, potentially through proteasomal degradation.
- This down-regulation of the decoy receptor TRAILR4 enhances sensitivity to TRAIL-mediated apoptosis.
- The findings suggest a dual mechanism for interferon-induced apoptosis: increased TRAIL in effector cells and decreased TRAILR4 in target cells.