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10:05
In Vitro Analysis of PDZ-dependent CFTR Macromolecular Signaling Complexes
Published on: August 13, 2012
Endosomal SNARE proteins regulate CFTR activity and trafficking in epithelial cells
Frédéric Bilan1, Magali Nacfer, Fleur Fresquet
1Institut de Physiologie et de Biologie Cellulaires, CNRS UMR6187, Université de Poitiers, France; CHU de Poitiers, BP577, 86021 Poitiers cedex, France.
Experimental Cell Research
|June 24, 2008
Summary
Endosomal SNARE proteins, including syntaxin 8, interact with Cystic Fibrosis Transmembrane conductance Regulator (CFTR) and regulate its trafficking and activity in epithelial cells.
Area of Science:
- Cell Biology
- Molecular Biology
- Epithelial Physiology
Background:
- The Cystic Fibrosis Transmembrane conductance Regulator (CFTR) protein functions as a chloride channel at the apical plasma membrane of epithelial cells.
- Syntaxin 8, an endosomal SNARE protein, was previously shown to interact with CFTR and influence its plasma membrane localization and channel activity.
Purpose of the Study:
- To investigate the physical and functional interactions between CFTR and the endosomal SNARE complex (syntaxin 7, syntaxin 8, vti1b, and VAMP8).
- To elucidate the role of endosomal SNARE proteins in regulating CFTR trafficking and activity in epithelial cells.
Main Methods:
- Overexpression of endosomal SNARE proteins in LLC-PK1 and Caco-2 cells.
- Measurement of CFTR activity and iodide efflux.
- Co-immunoprecipitation and pull-down assays to assess protein complex formation.
- Cell surface biotinylation and immunofluorescence microscopy to analyze CFTR localization.
- Colocalization studies with Rab11-positive recycling endosomes.
Main Results:
- Overexpression of endosomal SNARE proteins specifically inhibited CFTR activity, without affecting swelling- or calcium-activated iodide efflux.
- CFTR and endosomal SNARE proteins were found to form a complex, with VAMP8 and vti1b preferentially interacting with the CFTR N-terminus.
- Endosomal SNARE overexpression disrupted the apical targeting of CFTR.
- CFTR and endosomal SNARE proteins colocalized in Rab11-positive recycling endosomes.
Conclusions:
- Endosomal SNARE proteins physically and functionally interact with CFTR.
- These SNARE proteins play a role in regulating CFTR trafficking to the apical membrane.
- Endosomal SNARE proteins are involved in the recycling of CFTR within epithelial cells, potentially via Rab11-positive endosomes.
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