Regulation of Basolateral Cl− Channels in Airway Epithelial Cells: The Role of Nitric Oxide

Regulation of Basolateral Cl− Channels in Airway Epithelial Cells: The Role of Nitric Oxide The presence of basolateral Cl− channels in airway epithelium has been reported in several studies, but little is known about their role in the regulation of anion secretion. The purpose of this study was to characterize regulation of these channels by nitric oxide (NO) in Calu-3 cells. Transepithelial measurements revealed that NO donors activated a basolateral Cl− conductance sensitive to 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS) and anthracene-9-carboxylic acid. Apical membrane permeabilization studies confirmed the basolateral localization of NO-activated Cl− channels. Experiments using 8-bromo cyclic guanosine monophosphate (8Br-cGMP) and selective inhibitors of soluble guanylyl cyclase and inducible NO synthase (1H-[1, 2, 4] oxadiazolol-[4, 3-a] quinoxalin-1-one [ODQ] and 1400W [N-(3-Aminomethyl)benzyl)acetamidine], respectively) demonstrated that NO activated Cl− channels via a cGMP-dependent pathway. Anion replacement and 36Cl− flux studies showed that NO affected both Cl− and HCO 3 − secretion. Two different types of Cl− channels are known to be present in the basolateral membrane of epithelial cells: Zn2+-sensitive ClC-2 and DIDS-sensitive bestrophin channels. S-Nitrosoglutathione (GSNO) activated Cl− conductance in the presence of Zn2+ ions, indicating that ClC-2 channel function was not affected by GSNO. In contrast, DIDS completely inhibited GSNO-activated Cl− conductance. Bestrophin immunoprecipitation studies showed that under control conditions bestrophin channels were not phosphorylated but became phosphorylated after GSNO treatment. The presence of bestrophin in airway epithelia was confirmed using immunohistochemistry. We conclude that basolateral Cl− channels play a major role in the NO-dependent regulation of anion secretion in Calu-3 cells. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Regulation of Basolateral Cl− Channels in Airway Epithelial Cells: The Role of Nitric Oxide

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Publisher
Springer-Verlag
Copyright
Copyright © 2007 by Springer Science+Business Media, LLC
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-006-0062-x
Publisher site
See Article on Publisher Site

Abstract

The presence of basolateral Cl− channels in airway epithelium has been reported in several studies, but little is known about their role in the regulation of anion secretion. The purpose of this study was to characterize regulation of these channels by nitric oxide (NO) in Calu-3 cells. Transepithelial measurements revealed that NO donors activated a basolateral Cl− conductance sensitive to 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS) and anthracene-9-carboxylic acid. Apical membrane permeabilization studies confirmed the basolateral localization of NO-activated Cl− channels. Experiments using 8-bromo cyclic guanosine monophosphate (8Br-cGMP) and selective inhibitors of soluble guanylyl cyclase and inducible NO synthase (1H-[1, 2, 4] oxadiazolol-[4, 3-a] quinoxalin-1-one [ODQ] and 1400W [N-(3-Aminomethyl)benzyl)acetamidine], respectively) demonstrated that NO activated Cl− channels via a cGMP-dependent pathway. Anion replacement and 36Cl− flux studies showed that NO affected both Cl− and HCO 3 − secretion. Two different types of Cl− channels are known to be present in the basolateral membrane of epithelial cells: Zn2+-sensitive ClC-2 and DIDS-sensitive bestrophin channels. S-Nitrosoglutathione (GSNO) activated Cl− conductance in the presence of Zn2+ ions, indicating that ClC-2 channel function was not affected by GSNO. In contrast, DIDS completely inhibited GSNO-activated Cl− conductance. Bestrophin immunoprecipitation studies showed that under control conditions bestrophin channels were not phosphorylated but became phosphorylated after GSNO treatment. The presence of bestrophin in airway epithelia was confirmed using immunohistochemistry. We conclude that basolateral Cl− channels play a major role in the NO-dependent regulation of anion secretion in Calu-3 cells.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Apr 28, 2007

References

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