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Deoxygenation-induced alterations in sickle cell membrane cholesterol exchange
J Kavecansky1, F Schroeder, C H Joiner
1Department of Pediatrics, College of Medicine, University of Cincinnati, Ohio, USA.
The American Journal of Physiology
|November 1, 1995
Summary
Deoxygenation increases cholesterol exchange in sickle red blood cells (SS RBC) by altering membrane structure, particularly in spicules. This facilitates sterol exchange, impacting SS RBC membrane properties.
Area of Science:
- Biochemistry
- Cell Biology
- Hematology
Background:
- Sickle red blood cells (SS RBC) exhibit altered membrane properties compared to normal RBC.
- Membrane sterol composition and dynamics are crucial for red blood cell function and integrity.
Purpose of the Study:
- To investigate the effect of deoxygenation on membrane sterol exchange in SS RBC.
- To determine if increased sterol exchange is localized to specific membrane structures like spicules.
Main Methods:
- Utilized dehydroergosterol (DHE), a fluorescent cholesterol analogue, to track sterol exchange.
- Incubated SS RBC with DHE-loaded small unilamellar vesicles (SUV) under oxygenated and deoxygenated conditions.
- Analyzed DHE incorporation into intact SS RBC and isolated membrane spicules.
Main Results:
- Deoxygenation significantly increased the rate of DHE uptake by SS RBC membranes.
- Deoxygenated SS RBC showed higher DHE membrane content compared to oxygenated SS RBC.
- Isolated spicules from deoxygenated SS RBC contained threefold higher DHE, indicating localized increased sterol exchange.
Conclusions:
- Spicule formation in deoxygenated SS RBC alters membrane cholesterol structure.
- This alteration makes a previously non-exchangeable cholesterol domain readily exchangeable with exogenous sterols.
- The findings suggest a mechanism for altered membrane fluidity and function in sickle cell disease.