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Using kICS to Reveal Changed Membrane Diffusion of AQP-9 Treated with Drugs
Jakob L Kure1, Thommie Karlsson2,3, Camilla B Andersen1
1SDU Biotechnology, Department of Green Technology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
Image correlation spectroscopy (kICS) measured aquaporin-9 (AQP9) diffusion in cell membranes. Results suggest AQP9 is not part of membrane nanodomains, as drug treatments did not significantly alter its mobility.
Area of Science:
- Cell biology
- Biophysics
- Membrane protein dynamics
Background:
- Nanodomains in plasma membranes regulate protein function and signaling.
- Analyzing lateral mobility of membrane proteins is crucial for understanding their regulation.
- Image Correlation Spectroscopy (ICS) techniques, including k-space ICS (kICS), are advanced methods for studying molecular diffusion.
Purpose of the Study:
- To investigate the diffusion of aquaporin-9 (AQP9) in the plasma membrane using kICS.
- To determine the effect of drugs that perturb membrane and cytoskeleton on AQP9 diffusion.
- To assess whether AQP9 is localized within membrane nanodomains.
Main Methods:
- Live-cell Total Internal Reflection Fluorescence (TIRF) imaging on HEK-293 cells.
- Application of k-space Image Correlation Spectroscopy (kICS) to measure diffusion coefficients.
- Treatment with actin polymerization inhibitors (Cytochalasin D, Latrunculin A), Methyl-β-Cyclodextrin, and Human epidermal growth factor.
Main Results:
- Cytochalasin D and Latrunculin A did not alter the diffusion coefficient of AQP9.
- Methyl-β-Cyclodextrin significantly decreased the diffusion coefficient of GFP-AQP9.
- Human epidermal growth factor increased the diffusion coefficient of AQP9.
Conclusions:
- kICS is a viable technique for measuring AQP9 diffusion in live cells.
- The diffusion behavior of AQP9 suggests it is not associated with membrane nanodomains.
- Membrane-perturbing agents can modulate the mobility of AQP9 in the plasma membrane.
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