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BCL-xL-dependent light scattering by apoptotic cells.
Nada N Boustany1, Yien-Che Tsai, Bryan Pfister
1Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey 08854, USA. nboustan@rci.rutgers.edu
Biophysical Journal
|September 21, 2004
Summary
Optical Scatter Image Ratio (OSIR) detects early apoptosis in cells. Overexpressing BCL-xL protein reduces OSIR changes, suggesting it pre-conditions cells against apoptosis.
Area of Science:
- Cell biology
- Biophysics
- Apoptosis research
Background:
- Apoptosis is a critical biological process.
- BCL-xL is an antiapoptotic protein localized to mitochondria.
- Optical scatter image ratio (OSIR) measures cell morphology.
Purpose of the Study:
- To investigate OSIR as a real-time indicator of apoptosis.
- To assess the impact of BCL-xL overexpression on OSIR during apoptosis.
Main Methods:
- Single-cell analysis of OSIR in response to staurosporine (STS).
- Comparison of OSIR in parental, YFP-expressing, and YFP-BCL-xL-expressing cells.
- Correlation of OSIR changes with phosphatidyl serine exposure.
Main Results:
- STS treatment caused a ~25% OSIR decrease in control cells, preceding phosphatidyl serine exposure.
- YFP-BCL-xL cells exhibited a lower baseline OSIR and a <10% decrease after STS treatment.
- BCL-xL overexpression significantly attenuated the OSIR decrease during apoptosis.
Conclusions:
- OSIR is a sensitive, early biomarker for apoptosis.
- BCL-xL confers apoptosis resistance, potentially by altering mitochondrial morphology and preconditioning cells.
- OSIR can be used to study the mechanisms of apoptosis resistance.