Apoptosis and eryptosis: Striking differences on biomembrane level

Area of Science:

• Cell Biology
• Biochemistry
• Membrane Biophysics

Background:

• The cell plasma membrane is crucial for programmed cell death, including apoptosis in nucleated cells and eryptosis in erythrocytes.
• Similarities exist in plasma membrane changes due to loss of transmembrane asymmetry during both processes.

Purpose of the Study:

• To comparatively analyze membrane lipid order during apoptosis and eryptosis.
• To investigate the role of intracellular membranes in regulating plasma membrane changes during cell death.

Main Methods:

• Comparative studies utilizing a series of molecular probes.
• Analysis of membrane lipid order in nucleated cells and erythrocytes during apoptosis and eryptosis.

Main Results:

• Nucleated cells exhibit a significant drop in plasma membrane lipid order during apoptosis.
• Erythrocytes, in contrast, maintain a relatively high level of plasma membrane lipid order during eryptosis.
• Differences in lipid order between inner and plasma membranes in nucleated cells suggest inter-membrane lipid exchange.

Conclusions:

• The presence of intracellular membranes in nucleated cells facilitates phospholipid and/or cholesterol exchange, contributing to the observed decrease in plasma membrane lipid order during apoptosis.
• Erythrocytes, lacking intracellular membranes, cannot undergo such exchange, leading to the retention of high plasma membrane lipid order during eryptosis.