Transbilayer Coupling of Lipids in Cells Investigated by Imaging Fluorescence Correlation Spectroscopy
Nirmalya Bag1, Erwin London2, David A Holowka1
1Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States.
The Journal of Physical Chemistry. B
|March 16, 2022
Summary
Plasma membrane phase separation, regulated by transbilayer coupling, influences cellular signaling. New methods like Imaging Fluorescence Correlation Spectroscopy (ImFCS) precisely measure membrane diffusion to explore these lipid-driven processes.
Area of Science:
- Biophysics
- Cell Biology
- Membrane Biophysics
Background:
- Plasma membranes contain receptors and channels crucial for cellular signaling.
- Phase separation into liquid-ordered (Lo) and liquid-disordered (Ld) domains regulates signaling but is nanoscopic and transient in live cells.
- Transbilayer coupling, driven by lipid asymmetry and cytoskeleton-lipid interactions, is proposed to influence this phase separation.
Purpose of the Study:
- To highlight novel approaches for investigating how transbilayer coupling affects plasma membrane phase separation.
- To introduce Imaging Fluorescence Correlation Spectroscopy (ImFCS) for precise measurement of membrane diffusion and quantitative evaluation of transbilayer interactions.
- To explore lipid-mediated phase separation principles in live cells and their pathophysiological relevance.
Main Methods:
- Utilizing Imaging Fluorescence Correlation Spectroscopy (ImFCS) to precisely measure membrane diffusion.
- Employing model systems such as FcεRI/antigen and cholera toxin B/GM1 ganglioside interactions to study transbilayer coupling.
- Applying methods to perturb membrane lipid composition, including exogenous lipid exchange using methyl alpha cyclodextrin.
Main Results:
- Demonstrated the utility of ImFCS in quantitatively evaluating transbilayer coupling effects on membrane dynamics.
- Provided insights into how lipid composition and transbilayer interactions influence Lo/Ld phase separation.
- Established a framework for discovering novel principles of lipid-mediated phase separation in live cells.
Conclusions:
- Transbilayer coupling significantly impacts plasma membrane phase separation and dynamics.
- ImFCS and lipid perturbation strategies are powerful tools for dissecting complex membrane behaviors.
- Understanding these lipid-driven mechanisms is crucial for comprehending cellular signaling and disease.
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