Back to Search
Start Over
Carbonic anhydrase II binds to and increases the activity of the epithelial sodium-proton exchanger, NHE3
- Source :
- American Journal of Physiology-Renal Physiology. 309:F383-F392
- Publication Year :
- 2015
- Publisher :
- American Physiological Society, 2015.
-
Abstract
- Two-thirds of sodium filtered by the renal glomerulus is reabsorbed from the proximal tubule via a sodium/proton exchanger isoform 3 (NHE3)-dependent mechanism. Since sodium and bicarbonate reabsorption are coupled, we postulated that the molecules involved in their reabsorption [NHE3 and carbonic anhydrase II (CAII)] might physically and functionally interact. Consistent with this, CAII and NHE3 were closely associated in a renal proximal tubular cell culture model as revealed by a proximity ligation assay. Direct physical interaction was confirmed in solid-phase binding assays with immobilized CAII and C-terminal NHE3 glutathione- S-transferase fusion constructs. To assess the effect of CAII on NHE3 function, we expressed NHE3 in a proximal tubule cell line and measured NHE3 activity as the rate of intracellular pH recovery, following an acid load. NHE3-expressing cells had a significantly greater rate of intracellular pH recovery than controls. Inhibition of endogenous CAII activity with acetazolamide significantly decreased NHE3 activity, indicating that CAII activates NHE3. To ascertain whether CAII binding per se activates NHE3, we expressed NHE3 with wild-type CAII, a catalytically inactive CAII mutant (CAII-V143Y), or a mutant unable to bind other transporters (CAII-HEX). NHE3 activity increased upon wild-type CAII coexpression, but not in the presence of the CAII V143Y or HEX mutant. Together these studies support an association between CAII and NHE3 that alters the transporter's activity.
- Subjects :
- Sodium-Hydrogen Exchangers
Physiology
Renal glomerulus
Intracellular pH
Carbonic anhydrase II
Sodium
chemistry.chemical_element
Proximity ligation assay
Kidney
Transfection
Carbonic Anhydrase II
Article
Cell Line
03 medical and health sciences
0302 clinical medicine
Protein Interaction Mapping
Animals
Humans
Immunoprecipitation
Protein Interaction Domains and Motifs
Carbonic Anhydrase Inhibitors
030304 developmental biology
0303 health sciences
Sodium-Hydrogen Exchanger 3
urogenital system
Chemistry
Reabsorption
Transporter
Opossums
Hydrogen-Ion Concentration
Molecular biology
Recombinant Proteins
Bicarbonates
Kinetics
Cell culture
Mutation
Biophysics
030217 neurology & neurosurgery
Protein Binding
Subjects
Details
- ISSN :
- 15221466 and 1931857X
- Volume :
- 309
- Database :
- OpenAIRE
- Journal :
- American Journal of Physiology-Renal Physiology
- Accession number :
- edsair.doi.dedup.....229cad55e0bf416b9a96155f0cb8aed2
- Full Text :
- https://doi.org/10.1152/ajprenal.00464.2014