CFTR involvement in chloride, bicarbonate, and liquid secretion by airway submucosal glands

1999 ◽  
Vol 277 (4) ◽  
pp. L694-L699 ◽  
Author(s):  
Stephen T. Ballard ◽  
Laura Trout ◽  
Zsuzsa Bebök ◽  
E. J. Sorscher ◽  
Angela Crews
Keyword(s):  
Cystic Fibrosis ◽  
Channel Blocker ◽  
Polyclonal Antibodies ◽  
Surface Epithelium ◽  
Transmembrane Conductance Regulator ◽  
Submucosal Gland ◽  
Transmembrane Conductance ◽  
Active Secretion ◽  
Submucosal Glands ◽  
Cystic Fibrosis Transmembrane

Previous studies demonstrated that ACh-induced liquid secretion by porcine bronchi is driven by active Cl− and H[Formula: see text] secretion. The present study was undertaken to determine whether this process was localized to submucosal glands and mediated by the cystic fibrosis transmembrane conductance regulator (CFTR). When excised, cannulated, and treated with ACh, porcine bronchi secreted 15.6 ± 0.6 μl ⋅ cm−2 ⋅ h−1. Removal of the surface epithelium did not significantly affect the rate of secretion, indicating that the source of the liquid was the submucosal glands. Pretreatment with diphenylamine-2-carboxylate, a relatively nonselective Cl−-channel blocker, significantly reduced liquid secretion by 86%, whereas pretreatment with DIDS, which inhibits a variety of Cl− channels but not CFTR, had no effect. When bronchi were pretreated with glibenclamide or 5-nitro-2-(3-phenylpropylamino)benzoic acid (both inhibitors of CFTR), the rate of ACh-induced liquid secretion was significantly reduced by 39 and 91%, respectively, compared with controls. Agents that blocked liquid secretion also caused disproportionate reductions in H[Formula: see text] secretion. Polyclonal antibodies to the CFTR bound preferentially to submucosal gland ducts and the surface epithelium, suggesting that this channel was localized to these sites. These data suggest that ACh-induced gland liquid secretion by porcine bronchi is driven by active secretion of both Cl− and H[Formula: see text] and is mediated by the CFTR.

scholarly journals Correctors Promote Maturation of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)-processing Mutants by Binding to the Protein

2007 ◽  
Vol 282 (46) ◽  
pp. 33247-33251 ◽  
Author(s):  
Ying Wang ◽  
Tip W. Loo ◽  
M. Claire Bartlett ◽  
David M. Clarke
Keyword(s):  
Cystic Fibrosis ◽  
Channel Blocker ◽  
Cross Linking ◽  
Transmembrane Conductance Regulator ◽  
Mature Protein ◽  
Transmembrane Conductance ◽  
P Glycoprotein ◽  
Δf508 Cftr ◽  
Cross Linker ◽  
Cystic Fibrosis Transmembrane

The most common cause of cystic fibrosis (CF) is defective folding of a cystic fibrosis transmembrane conductance regulator (CFTR) mutant lacking Phe508 (ΔF508). The ΔF508 protein appears to be trapped in a prefolded state with incomplete packing of the transmembrane (TM) segments, a defect that can be repaired by expression in the presence of correctors such as corr-4a, VRT-325, and VRT-532. To determine whether the mechanism of correctors involves direct interactions with CFTR, our approach was to test whether correctors blocked disulfide cross-linking between cysteines introduced into the two halves of a Cys-less CFTR. Although replacement of the 18 endogenous cysteines of CFTR with Ser or Ala yields a Cys-less mutant that does not mature at 37 °C, we found that maturation could be restored if Val510 was changed to Ala, Cys, Ser, Thr, Gly, Ala, or Asp. The V510D mutation also promoted maturation of ΔF508 CFTR. The Cys-less/V510A mutant was used for subsequent cross-linking analysis as it yielded relatively high levels of mature protein that was functional in iodide efflux assays. We tested for cross-linking between cysteines introduced into TM6 and TM7 of Cys-less CFTR/V510A because cross-linking between TM6 and TM7 of P-glycoprotein, the sister protein of CFTR, was inhibited with the corrector VRT-325. Cys-less CFTR/V510A mutant containing cysteines at I340C(TM6) and S877C(TM7) could be cross-linked with a homobifunctional cross-linker. Correctors and the CFTR channel blocker benzbromarone, but not P-glycoprotein substrates, inhibited cross-linking of mutant I340C(TM6)/S877C(TM7). These results suggest that corrector molecules such as corr-4a interact directly with CFTR.

scholarly journals Mechanism of substance P-induced liquid secretion across bronchial epithelium

2001 ◽  
Vol 281 (3) ◽  
pp. L639-L645 ◽  
Author(s):  
Laura Trout ◽  
Michel R. Corboz ◽  
Stephen T. Ballard
Keyword(s):  
Substance P ◽  
Anion Channel ◽  
Bronchial Epithelium ◽  
Surface Epithelium ◽  
Channel Blockers ◽  
Transmembrane Conductance Regulator ◽  
Inhibitory Effects ◽  
Transmembrane Conductance ◽  
Submucosal Glands ◽  
Cystic Fibrosis Transmembrane

The present study was undertaken to identify and determine the mechanism of noncholinergic pathways for the induction of liquid secretion across airway epithelium. Excised porcine bronchi secreted substantial and significant quantities of liquid when exposed to acetylcholine, substance P, or forskolin but not to isoproterenol, norepinephrine, or phenylephrine. Bumetanide, an inhibitor of Na+-K+-2Cl− cotransport, reduced the liquid secretion response to substance P by 69%. Approximately two-thirds of bumetanide-insensitive liquid secretion was blocked by dimethylamiloride (DMA), a Na+/H+ exchange inhibitor. Substance P responses were preserved in airways after surface epithelium removal, suggesting that secreted liquid originated from submucosal glands. The anion channel blockers diphenylamine-2-carboxylate (DPC) and 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) inhibited >90% of substance P-induced liquid secretion, whereas DIDS had no effect. DMA, DPC, and NPPB had greater inhibitory effects on net HCO[Formula: see text] secretion than on liquid secretion. Although preserved relative to liquid secretion, net HCO[Formula: see text]secretion was reduced by 39% in the presence of bumetanide. We conclude that substance P induces liquid secretion from bronchial submucosal glands of pigs through active transport of Cl−and HCO[Formula: see text]. The pattern of responses to secretion agonists and antagonists suggests that the cystic fibrosis transmembrane conductance regulator mediates this process.

scholarly journals Evidence that Calu-3 human airway cells secrete bicarbonate

1998 ◽  
Vol 274 (3) ◽  
pp. L450-L453 ◽  
Author(s):  
Michael C. Lee ◽  
Christopher M. Penland ◽  
Jonathan H. Widdicombe ◽  
Jeffrey J. Wine
Keyword(s):  
Cystic Fibrosis ◽  
Previous Investigation ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Disulfonic Acid ◽  
Transmembrane Conductance Regulator ◽  
Submucosal Gland ◽  
Transmembrane Conductance ◽  
Air Interface ◽  
Cystic Fibrosis Transmembrane

The Calu-3 cell line is being investigated as a model for human submucosal gland serous cells. In a previous investigation of basal short-circuit current ( I sc) in Calu-3 cells, high levels of bumetanide-insensitive basal I sc (∼60 μA/cm2) were measured in cells grown at an air interface. Basal I sc was reduced only 7% by bumetanide, and the largest component of basal I sc required both Cl− and[Formula: see text] in the bathing solutions. Because I sc could be partially inhibited by basolateral 4,4′-dinitrostilbene-2,2′-disulfonic acid and because the only known apical exit pathway for anions is the cystic fibrosis transmembrane conductance regulator, which has a relatively poor conductance for [Formula: see text], it was concluded that most basal I sc is[Formula: see text]-dependent Cl− secretion [M. Singh, M. Krouse, S. Moon, and J. J. Wine. Am. J. Physiol. 272 ( Lung Cell. Mol. Physiol. 16): L690–L698, 1997]. We have now measured isotopic fluxes of36Cl−and22Na+across short-circuited Calu-3 cells and found that virtually none of the basal I sc is Cl− secretion or Na+ absorption. Thus, in contrast to the earlier report, we conclude that the major component of basal I sc is[Formula: see text] secretion. Stimulation recruits primarily Cl− secretion, as previously proposed.

scholarly journals Bicarbonate and Chloride Secretion in Calu-3 Human Airway Epithelial Cells

1999 ◽  
Vol 113 (5) ◽  
pp. 743-760 ◽  
Author(s):  
Daniel C. Devor ◽  
Ashvani K. Singh ◽  
Linda C. Lambert ◽  
Arthur DeLuca ◽  
Raymond A. Frizzell ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Basolateral Membrane ◽  
Disulfonic Acid ◽  
Transmembrane Conductance Regulator ◽  
Submucosal Gland ◽  
Transmembrane Conductance ◽  
Cl Secretion ◽  
Human Airway ◽  
Serous Cell ◽  
Cystic Fibrosis Transmembrane

Serous cells are the predominant site of cystic fibrosis transmembrane conductance regulator expression in the airways, and they make a significant contribution to the volume, composition, and consistency of the submucosal gland secretions. We have employed the human airway serous cell line Calu-3 as a model system to investigate the mechanisms of serous cell anion secretion. Forskolin-stimulated Calu-3 cells secrete HCO−3 by a Cl −-independent, serosal Na+-dependent, serosal bumetanide-insensitive, and serosal 4,4′-dinitrostilben-2,2′-disulfonic acid (DNDS)–sensitive, electrogenic mechanism as judged by transepithelial currents, isotopic fluxes, and the results of ion substitution, pharmacology, and pH studies. Similar studies revealed that stimulation of Calu-3 cells with 1-ethyl-2-benzimidazolinone (1-EBIO), an activator of basolateral membrane Ca2+-activated K+ channels, reduced HCO−3 secretion and caused the secretion of Cl − by a bumetanide-sensitive, electrogenic mechanism. Nystatin permeabilization of Calu-3 monolayers demonstrated 1-EBIO activated a charybdotoxin- and clotrimazole- inhibited basolateral membrane K+ current. Patch-clamp studies confirmed the presence of an intermediate conductance inwardly rectified K+ channel with this pharmacological profile. We propose that hyperpolarization of the basolateral membrane voltage elicits a switch from HCO−3 secretion to Cl − secretion because the uptake of HCO−3 across the basolateral membrane is mediated by a 4,4 ′-dinitrostilben-2,2′-disulfonic acid (DNDS)–sensitive Na+:HCO−3 cotransporter. Since the stoichiometry reported for Na +:HCO−3 cotransport is 1:2 or 1:3, hyperpolarization of the basolateral membrane potential by 1-EBIO would inhibit HCO−3 entry and favor the secretion of Cl −. Therefore, differential regulation of the basolateral membrane K+ conductance by secretory agonists could provide a means of stimulating HCO−3 and Cl − secretion. In this context, cystic fibrosis transmembrane conductance regulator could serve as both a HCO−3 and a Cl − channel, mediating the apical membrane exit of either anion depending on basolateral membrane anion entry mechanisms and the driving forces that prevail. If these results with Calu-3 cells accurately reflect the transport properties of native submucosal gland serous cells, then HCO−3 secretion in the human airways warrants greater attention.

scholarly journals Compartmentalized Cyclic Adenosine 3′,5′-Monophosphate at the Plasma Membrane Clusters PDE3A and Cystic Fibrosis Transmembrane Conductance Regulator into Microdomains

2010 ◽  
Vol 21 (6) ◽  
pp. 1097-1110 ◽  
Author(s):  
Himabindu Penmatsa ◽  
Weiqiang Zhang ◽  
Sunitha Yarlagadda ◽  
Chunying Li ◽  
Veronica G. Conoley ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Plasma Membrane ◽  
Gland Secretion ◽  
Macromolecular Complex ◽  
Transmembrane Conductance Regulator ◽  
Submucosal Gland ◽  
Transmembrane Conductance ◽  
Channel Function ◽  
Phosphodiesterase Type ◽  
Cystic Fibrosis Transmembrane

Formation of multiple-protein macromolecular complexes at specialized subcellular microdomains increases the specificity and efficiency of signaling in cells. In this study, we demonstrate that phosphodiesterase type 3A (PDE3A) physically and functionally interacts with cystic fibrosis transmembrane conductance regulator (CFTR) channel. PDE3A inhibition generates compartmentalized cyclic adenosine 3′,5′-monophosphate (cAMP), which further clusters PDE3A and CFTR into microdomains at the plasma membrane and potentiates CFTR channel function. Actin skeleton disruption reduces PDE3A–CFTR interaction and segregates PDE3A from its interacting partners, thus compromising the integrity of the CFTR-PDE3A–containing macromolecular complex. Consequently, compartmentalized cAMP signaling is lost. PDE3A inhibition no longer activates CFTR channel function in a compartmentalized manner. The physiological relevance of PDE3A–CFTR interaction was investigated using pig trachea submucosal gland secretion model. Our data show that PDE3A inhibition augments CFTR-dependent submucosal gland secretion and actin skeleton disruption decreases secretion.

Production and characterisation of monoclonal and polyclonal antibodies to different regions of the cystic fibrosis transmembrane conductance regulator (CFTR): detection of immunologically related proteins

1995 ◽  
Vol 108 (6) ◽  
pp. 2433-2444
Author(s):  
J. Walker ◽  
J. Watson ◽  
C. Holmes ◽  
A. Edelman ◽  
G. Banting
Keyword(s):  
Cystic Fibrosis ◽  
Fusion Proteins ◽  
Synthetic Peptides ◽  
Polyclonal Antibodies ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Polyclonal Antisera ◽  
Related Proteins ◽  
Cystic Fibrosis Transmembrane ◽  
Beta Galactosidase

We have raised mouse monoclonal antibodies to eight synthetic peptides corresponding to different regions of the human cystic fibrosis transmembrane conductance regulator (CFTR) and rabbit polyclonal antisera to beta-galactosidase fusion proteins which encompass three different regions of CFTR. Immunoblot, immunoprecipitation, immunofluorescence and immunocytochemical experiments demonstrate that, in addition to recognising CFTR, these antibodies recognise one or more immunologically related proteins with a similar molecular mass, calcium responsiveness and tissue distribution to CFTR.

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