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Epithelial sodium channel is regulated by SNAP-23/syntaxin 1A interplay
Sunil K Saxena1, Constantine M George, Vadim Pinskiy
1Center for Cell and Molecular Biology, Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, NJ 07030, USA. ssaxena@stevens.edu
Biochemical and Biophysical Research Communications
|April 4, 2006
Summary
Soluble N-ethylmaleimide-sensitive attachment receptors (SNAREs), specifically SNAP-23, modulate epithelial sodium channel (ENaC) activity. This SNARE protein interplay fine-tunes sodium reabsorption in tight epithelia.
Area of Science:
- Cell Biology
- Molecular Physiology
- Membrane Transport
Background:
- Epithelial sodium channel (ENaC) is crucial for sodium reabsorption in epithelia.
- Soluble N-ethylmaleimide-sensitive attachment receptors (SNAREs) regulate vesicle trafficking.
- Syntaxin, a t-SNARE, interacts with and regulates ion channels, including ENaC.
Purpose of the Study:
- To investigate the role of SNAP-23, a SNARE protein, in regulating ENaC activity.
- To explore the interaction between SNAP-23 and ENaC in colonic epithelial cells and Xenopus oocytes.
- To elucidate the complex interplay of SNARE proteins in fine-tuning sodium channel function.
Main Methods:
- Electrophysiological recordings of amiloride-sensitive currents in HT-29 cells and Xenopus oocytes.
- Functional assays using Botulinum toxins to cleave SNAP-23.
- Biochemical pull-down assays to assess protein interactions.
Main Results:
- SNAP-23 was found to modulate ENaC activity, inhibiting it at higher concentrations.
- Botulinum toxin A reversed the inhibitory effect of SNAP-23, confirming SNAP-23's role.
- Evidence suggests a complex quaternary interaction involving ENaC, SNAP-23, and syntaxin 1A, potentially with the N-terminal alphaENaC.
Conclusions:
- SNARE proteins, particularly SNAP-23, play a significant role in regulating ENaC function.
- The interaction between ENaC and the exocytotic machinery, mediated by SNAREs, is complex.
- SNARE protein interplay is essential for the fine-tuning of sodium channel activity in epithelial cells.