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Enrichment of Mammalian Tissues and Xenopus Oocytes with Cholesterol
Published on: March 25, 2020
Plasma membrane cholesterol content affects nitric oxide diffusion dynamics and signaling
Shane Miersch1, Michael Graham Espey, Ruchi Chaube
1Department of Chemistry and Biochemistry University of Windsor, Windsor Ontario N9B 3P4, Canada.
The Journal of Biological Chemistry
|May 1, 2008
Summary
Cholesterol in cell membranes hinders nitric oxide (NO) diffusion, impacting NO signaling pathways. Reducing membrane cholesterol restores NO signaling, highlighting cholesterol
Area of Science:
- Biochemistry
- Cell Biology
- Membrane Biophysics
Background:
- Nitric oxide (NO) is a crucial signaling molecule with properties influenced by its hydrophobic nature.
- NO readily partitions into biological membranes, suggesting membrane composition affects its diffusion and signaling.
- Cholesterol is a key component of plasma membranes, known to modulate membrane fluidity and structure.
Purpose of the Study:
- To investigate the hypothesis that plasma membrane cholesterol content influences nitric oxide (NO) diffusion and cellular signaling.
- To elucidate the relationship between cholesterol-induced membrane ordering and the spatial regulation of NO signaling.
Main Methods:
- Fluorescence lifetime quenching studies using pyrene-labeled liposomes to measure NO diffusion coefficients.
- Electrochemical measurements across artificial bilayer membranes with varying cholesterol concentrations.
- Analysis of NO-induced signaling in Niemann-Pick type C1 (NPC1) fibroblasts (high cholesterol) and normal human fibroblasts (NHF), with manipulation of cholesterol levels.
Main Results:
- Cholesterol significantly decreased NO diffusion coefficients in liposomes (20-40%) and across artificial membranes.
- NPC1 fibroblasts with elevated membrane cholesterol showed reduced NO-induced activation of soluble guanylyl cyclase and VASP phosphorylation.
- Modulating membrane cholesterol in both NPC1 and NHF cells directly altered NO-mediated cGMP production and VASP phosphorylation, and extracellular nitrosation.
Conclusions:
- Plasma membrane cholesterol content directly impacts the physical diffusion of nitric oxide (NO).
- Cholesterol-mediated changes in membrane fluidity and microdomain structure contribute to the spatial regulation of NO diffusion and signaling.
- These findings reveal a critical link between membrane lipid composition and the efficacy of NO-based cellular communication.
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