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Characterization of Plasma Membrane Ceramides by Super-Resolution Microscopy
Anne Burgert1, Jan Schlegel1, Jérôme Bécam2
1Department of Biotechnology and Biophysics, Julius Maximilian University Würzburg, Am Hubland, 97074, Würzburg, Germany.
Angewandte Chemie (International Ed. in English)
|April 6, 2017
Summary
This study reveals that ceramides form distinct platforms on cell membranes, influencing cellular processes. Enhancing ceramide levels increases the size and number of these crucial membrane platforms.
Area of Science:
- Cell Biology
- Membrane Biophysics
- Lipid Signaling
Background:
- Sphingolipids, particularly ceramide, are key regulators of fundamental cellular processes including differentiation, proliferation, growth arrest, and apoptosis.
- Ceramide-rich membrane areas (CRMs) are known to influence plasma membrane structure, affecting receptor segregation, membrane curvature, and vesicle dynamics.
Purpose of the Study:
- To visualize and characterize the distribution of ceramides on the plasma membrane at near-molecular resolution.
- To investigate the formation and properties of ceramide-rich platforms (CRPs) in different cell types.
- To determine the effect of increased ceramide levels on CRPs.
Main Methods:
- Immunocytochemistry was employed to label ceramides.
- Direct stochastic optical reconstruction microscopy (dSTORM) was utilized for super-resolution imaging of ceramide distribution.
- Bacillus cereus sphingomyelinase (bSMase) was used to modulate cellular ceramide concentrations.
Main Results:
- Super-resolution microscopy revealed that 50-60% of membrane ceramides are localized within ceramide-rich platforms (CRPs) of approximately 75 nm in size, each containing at least 20 ceramide molecules.
- These CRPs were observed independently of labeling conditions and cell type.
- Treatment with bSMase significantly increased overall plasma membrane ceramide concentration, leading to an increase in both the quantity and size of CRPs, with a twofold rise in ceramide concentration within the CRPs.
Conclusions:
- Ceramides self-organize into distinct, stable platforms on the plasma membrane, irrespective of cell type.
- These ceramide-rich platforms (CRPs) play a significant role in membrane organization and potentially in regulating cellular functions.
- Modulating ceramide levels directly impacts the formation and composition of these critical membrane microdomains.