Bachhuber, Tanja and Koenig, Jens and Voelcker, Thilo and Muerle, Bettina and Schreiber, Rainer and Kunzelmann, Karl (2005) Cl- interference with the epithelial Na+ channel ENaC. JOURNAL OF BIOLOGICAL CHEMISTRY, 280 (36). pp. 31587-31594. ISSN 0021-9258, 1083-351X
Full text not available from this repository. (Request a copy)Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is a protein kinase A and ATP-regulated Cl- channel that also controls the activity of other membrane transport proteins, such as the epithelial Na+ channel ENaC. Previous studies demonstrated that cytosolic domains of ENaC are critical for down-regulation of ENaC by CFTR, whereas others suggested a role of cytosolic Cl- ions. We therefore examined in detail the anion dependence of ENaC and the role of its cytosolic domains for the inhibition by CFTR and the Cl- channel CLC-0. Coexpression of rat ENaC with human CFTR or the human Cl- channel CLC-0 caused inhibition of amiloride-sensitive Na+ currents after cAMP-dependent stimulation and in the presence of a 100 mM bath Cl- concentration. After activation of CFTR by 3-isobutyl-1-methylxanthine and forskolin or expression of CLC-0, the intracellular Cl- concentration was increased in Xenopus oocytes in the presence of a high bath Cl- concentration, which inhibited ENaC without changing surface expression of alpha beta gamma ENaC. In contrast, a 5 mM bath Cl- concentration reduced the cytosolic Cl- concentration and enhanced ENaC activity. ENaC was also inhibited by injection of Cl- into oocytes and in inside/out macropatches by exposure to high cytosolic Cl- concentrations. The effect of Cl- was mimicked by Br-, NO3-, and I-. Inhibition by Cl- was reduced in trimeric channels with a truncated COOH terminus of beta ENaC and gamma ENaC, and it was no longer detected in dimeric alpha beta gamma ENaC channels. Deletion of the NH2 terminus of alpha-, beta-, or gamma ENaC, mutations in the NH2-terminal phosphatidylinositol bisphosphate-binding domain of beta ENaC and gamma EnaC, and activation of phospholipase C, all reduced ENaC activity but allowed for Cl--dependent inhibition of the remaining ENaC current. The results confirm a role of the carboxyl terminus of beta ENaC for Cl-- dependent inhibition of the Na+ channel, which, however, may only be part of a complex regulation of ENaC by CFTR.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | TRANSMEMBRANE CONDUCTANCE REGULATOR; PDZ-INTERACTING DOMAIN; COLLECTING DUCT CELLS; CYSTIC-FIBROSIS; SODIUM-CHANNEL; XENOPUS OOCYTES; CHLORIDE CHANNEL; FUNCTIONAL INTERACTIONS; PURINERGIC STIMULATION; SURFACE EXPRESSION; |
| Subjects: | 500 Science > 570 Life sciences |
| Divisions: | Biology, Preclinical Medicine > Institut für Physiologie > Prof. Dr. Karl Kunzelmann |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 27 Apr 2021 07:50 |
| Last Modified: | 27 Apr 2021 07:50 |
| URI: | https://pred.uni-regensburg.de/id/eprint/35626 |
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