scholarly journals Nobiletin Stimulates Chloride Secretion in Human Bronchial Epithelia via a cAMP/PKA-Dependent Pathway

2015 ◽  
Vol 37 (1) ◽  
pp. 306-320 ◽  
Author(s):  
Yuan Hao ◽  
Cindy S.T. Cheung ◽  
Wallace C.Y. Yip ◽  
Wing-hung Ko

Background/Aims: Nobiletin, a citrus flavonoid isolated from tangerines, alters ion transport functions in intestinal epithelia, and has antagonistic effects on eosinophilic airway inflammation of asthmatic rats. The present study examined the effects of nobiletin on basal short-circuit current (ISC) in a human bronchial epithelial cell line (16HBE14o-), and characterized the signal transduction pathways that allowed nobiletin to regulate electrolyte transport. Methods: The ISC measurement technique was used for transepithelial electrical measurements. Intracellular calcium ([Ca2+]i) and cAMP were also quantified. Results: Nobiletin stimulated a concentration-dependent increase in ISC, which was due to Cl- secretion. The increase in ISC was inhibited by a cystic fibrosis transmembrane conductance regulator inhibitor (CFTRinh-172), but not by 4,4'-diisothiocyano-stilbene-2,2'-disulphonic acid (DIDS), Chromanol 293B, clotrimazole, or TRAM-34. Nobiletin-stimulated ISC was also sensitive to a protein kinase A (PKA) inhibitor, H89, and an adenylate cyclase inhibitor, MDL-12330A. Nobiletin could not stimulate any increase in ISC in a cystic fibrosis (CF) cell line, CFBE41o-, which lacked a functional CFTR. Nobiletin stimulated a real-time increase in cAMP, but not [Ca2+]i. Conclusion: Nobiletin stimulated transepithelial Cl- secretion across human bronchial epithelia. The mechanisms involved activation of adenylate cyclase- and cAMP/PKA-dependent pathways, leading to activation of apical CFTR Cl- channels.

2001 ◽  
Vol 281 (1) ◽  
pp. L24-L30 ◽  
Author(s):  
Lin Gao ◽  
James R. Broughman ◽  
Takeo Iwamoto ◽  
John M. Tomich ◽  
Charles J. Venglarik ◽  
...  

Cystic fibrosis (CF), an inherited disease characterized by defective epithelial Cl−transport, damages lungs via chronic inflammation and oxidative stress. Glutathione, a major antioxidant in the epithelial lung lining fluid, is decreased in the apical fluid of CF airway epithelia due to reduced glutathione efflux (Gao L, Kim KJ, Yankaskas JR, and Forman HJ. Am J Physiol Lung Cell Mol Physiol 277: L113–L118, 1999). The present study examined the question of whether restoration of chloride transport would also restore glutathione secretion. We found that a Cl− channel-forming peptide (N-K4-M2GlyR) and a K+ channel activator (chlorzoxazone) increased Cl− secretion, measured as bumetanide-sensitive short-circuit current, and glutathione efflux, measured by high-performance liquid chromatography, in a human CF airway epithelial cell line (CFT1). Addition of the peptide alone increased glutathione secretion (181 ± 8% of the control value), whereas chlorzoxazone alone did not significantly affect glutathione efflux; however, chlorzoxazone potentiated the effect of the peptide on glutathione release (359 ± 16% of the control value). These studies demonstrate that glutathione efflux is associated with apical chloride secretion, not with the CF transmembrane conductance regulator per se, and the defect of glutathione efflux in CF can be overcome pharmacologically.


1991 ◽  
Vol 261 (6) ◽  
pp. G958-G965 ◽  
Author(s):  
A. B. Vaandrager ◽  
R. Bajnath ◽  
J. A. Groot ◽  
A. G. Bot ◽  
H. R. De Jonge

The mechanism of adenosine 3',5'-cyclic monophosphate (cAMP)- and Ca(2+)-induced Cl- secretion was studied in monolayers of the colon carcinoma cell line HT-29.cl19A by combined short-circuit current (Isc) and 125I- or 36Cl- efflux measurements. Forskolin, a specific adenylate cyclase activator, was found to induce a large increase in Isc and a two- to threefold increase in 36Cl- efflux solely across the apical border. The fractional efflux of 36Cl-compared with 125I- (basal ratio 1.71 +/- 0.28) did not change significantly in the presence of forskolin (1.91 +/- 0.45). In contrast, the Ca2+ ionophore A23187 did not appreciably affect the Isc but enhanced 36Cl- and 125I- efflux at the apical and basolateral side of the monolayer. Furthermore, the fractional efflux ratio of 36Cl- to 125I- changed dramatically to a value of 0.36 +/- 0.14. Both forskolin- and A23187-induced 36Cl- or 125I- efflux were only weakly inhibited by the putative Cl- channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoicacid. Carbachol, a Ca(2+)-linked agonist, mimicked the effects of A23187 on the 36Cl- and 125I- efflux but additionally provoked a significant increase in Isc. These data show that Ca2+ and cAMP activate different Cl-efflux pathways in HT-29.cl19A cells. Most likely these pathways represent a cAMP-activated conductance in the apical membrane and a separate Ca(2+)-activated Cl- conductance expressed in both apical and basolateral membranes. Apparently cholinergic agonists induce net electrogenic Cl- secretion through an intracellular signaling pathway (e.g., protein kinase C activation) different from the one activated by Ca2+/Ca2+ ionophore alone.


1992 ◽  
Vol 262 (2) ◽  
pp. G249-G256 ◽  
Author(s):  
A. B. Vaandrager ◽  
N. van den Berghe ◽  
A. G. Bot ◽  
H. R. de Jonge

Phorbol 12-myristate 13-acetate (PMA) was found to increase both the short-circuit current (Isc) and the efflux of 125I- or 36Cl- in the colonic epithelial cell line HT-29.cl19A. Neither the PMA-provoked rise in Isc nor the stimulation of 125I- efflux was affected by the cyclooxygenase inhibitor indomethacin. The PMA-induced increase in Cl- efflux was not accompanied by a rise in adenosine 3',5'-cyclic monophosphate (cAMP) levels. A prolonged incubation with PMA (3 h), however, inhibited the PMA- and the cAMP-stimulated Isc by greater than 90%, whereas the cAMP-provoked 125I- and 36Cl- efflux was not inhibited. The long-term PMA treatment was found to inhibit the basal and cAMP-provoked 86Rb+ efflux by 65 +/- 9 and 86 +/- 7%, respectively. A 3-h incubation with PMA also strongly inhibited the Ca2+ ionophore A23187-induced increase in 86Rb+ efflux, whereas the A23187-stimulated 125I- efflux was only marginally inhibited. These data suggest that phorbol esters, presumably by activation of protein kinase C, can provoke Cl- secretion in HT-29.cl19A colonocytes independently of a prostaglandin- or cAMP-mediated pathway. Prolonged exposure to PMA, however, causes an inhibition of net electrogenic Cl- secretion by downregulation of the activity of K+ transporters.


1991 ◽  
Vol 261 (2) ◽  
pp. L188-L194 ◽  
Author(s):  
P. I. Plews ◽  
Z. A. Abdel-Malek ◽  
C. A. Doupnik ◽  
G. D. Leikauf

The endothelins (ET) are a group of isopeptides produced by a number of cells, including canine tracheal epithelial cells. Because these compounds are endogenous peptides that may activate eicosanoid metabolism, we investigated the effects of ET on Cl secretion in canine tracheal epithelium. Endothelin 1 (ET-1) was found to produce a dose-dependent change in short-circuit current (Isc) that increased slowly and reached a maximal value within 10-15 min. When isopeptides of ET were compared, 300 nM ET-1 and ET-2 produced comparable maximal increases in Isc, whereas ET-3 produced smaller changes in Isc (half-maximal concentrations of 2.2, 7.2, and 10.4 nM, respectively). Ionic substitution of Cl with nontransported anions, iodide and gluconate, reduced ET-1-induced changes in Isc. Furthermore, the response was inhibited by the NaCl cotransport inhibitor, furosemide. In paired tissues, ET-1 significantly increased mucosal net 36Cl flux without significant effect on 22Na flux. The increase in Isc induced by ET was diminished by pretreatment with indomethacin. The second messengers mediating the increase in Isc were investigated in cultured canine tracheal epithelial cells. ET-1 stimulated the release of [3H]arachidonate from membrane phospholipids, increased intracellular Ca2+ (occasionally producing oscillations), and increased adenosine 3',5'-cyclic monophosphate accumulation. The latter was diminished by indomethacin. Thus ET is a potent agonist of Cl secretion (with the isopeptides having the following potency: ET-1 greater than or equal to ET-2 greater than ET-3) and acts, in part, through a cyclooxygenase-dependent mechanism.


2018 ◽  
Vol 49 (2) ◽  
pp. 626-637 ◽  
Author(s):  
Rui-Gang Zhang ◽  
Chung-Yin Yip ◽  
Wing-hung Ko

Background/Aims: Carbon monoxide (CO) is an important gas produced endogenously by heme oxygenase (HO) that functions as an anti-inflammatory and in ion channel modulation, but the effects of CO on airway inflammation and ion transport remains unclear. Methods: The effect of CO on cell damage- and nucleotide-induced pro-inflammatory cytokine release in primary human bronchial epithelia cells (HBE) and in the 16HBE14o- human bronchial epithelial cell line were investigated. The effects of CO on calcium- and cAMP-dependent chloride (Cl-) secretion were examined using a technique that allowed the simultaneous measurement and quantification of real-time changes in signalling molecules (cAMP and Ca2+) and ion transport in a polarised epithelium. Results: CO suppressed the release of interleukin (IL)-6 and IL-8 and decreased the phosphorylation of ERK1/2 and NF-κB p65. Furthermore, CO inhibited UTP-induced increases in calcium and Cl- secretion, and forskolin-induced increases in cAMP and Cl- secretion. Conclusions: These findings suggest a novel anti-inflammatory role of CO in human bronchial epithelia via interactions with purinergic signalling pathways. Further, CO modulated both the Ca2+- and cAMP-dependent secretion of Cl-.


1993 ◽  
Vol 264 (2) ◽  
pp. G252-G260 ◽  
Author(s):  
V. Calderaro ◽  
E. Chiosi ◽  
R. Greco ◽  
A. M. Spina ◽  
A. Giovane ◽  
...  

Effects of Ca2+ on adenosine 3',5'-cyclic monophosphate (cAMP)-mediated Cl- secretion were investigated in intact mucosa and isolated crypt cells of rabbit descending colon. Addition of 10 microM prostaglandin (PG)E2 or forskolin to tissues incubated in Ca(2+)-free medium increased the size of short-circuit current (Isc) and Cl- secretion as estimated by unidirectional 36Cl flux measurements (net flux = -2.31 +/- 0.24 vs. -1.22 +/- 0.10 mueq.h-1.cm-2, n = 4, P < 0.001). Addition of 10 microM PGE2 to tissues incubated in 1.2 mM Ca2+ Ringer induced a 7-fold increase in mean cAMP level, whereas it produced an 11-fold increase in tissues exposed to Ca(2+)-free medium. Membrane preparations from whole mucosa incubated in Ca(2+)-free medium displayed a cyclic nucleotide phosphodiesterase activity significantly lower than controls (18.76 +/- 0.54 vs. 31.20 +/- 0.39 pmol cAMP. mg protein-1.min-1, means +/- SE, n = 4, P < 0.001). Ca2+ removal also affected adenylate cyclase (AC) responsiveness to agonists; AC activity increased in controls by 54 and 226% after stimulation with 10 microM PGE2 and forskolin, respectively, but it increased more (77 and 325%, respectively) after incubation in Ca(2+)-free solutions.(ABSTRACT TRUNCATED AT 250 WORDS)


1988 ◽  
Vol 255 (1) ◽  
pp. G27-G32 ◽  
Author(s):  
G. Warhurst ◽  
N. B. Higgs ◽  
M. Lees ◽  
A. Tonge ◽  
L. A. Turnberg

We examined the possibility that the protein kinase C pathway may interact with the adenosine 3',5'-cyclic monophosphate (cAMP) pathway in intestinal epithelium by studying the influence of phorbol esters on the response to prostaglandin E2 (PGE2) in a colonic epithelial cell line. Pretreatment of T84 cells with 4 beta-phorbol 12,13-dibutyrate (PDB) markedly attenuated the rise in short-circuit current provoked by PGE2, a receptor-mediated cAMP agonist. The EC50 of this effect was 52 nM PDB with a half time of 4-6 min. The responses to nonreceptor-mediated agonists, forskolin and dibutyryl cAMP, were unaffected by phorbol ester. PDB also reduced the ability of PGE2 to stimulate adenylate cyclase activity in these cells. The accumulation of cAMP in response to PGE2 was inhibited by PDB (EC50 38 nM), an effect mimicked by the diacylglycerol analogue 1-oleoyl-2-acetyl-sn-glycerol. In addition, PGE2 stimulation of adenylate cyclase in membranes from PDB-treated cells was reduced by 30-40%. Inhibition was not mediated via the catalytic or regulatory subunit of the adenylate cyclase, implying an action involving desensitization of PGE2 receptors. These results provide evidence of a complex interrelationship between protein kinase C- and cAMP-mediated pathways that might be important in regulating the cellular response to secretagogues.


1997 ◽  
Vol 273 (1) ◽  
pp. C148-C160 ◽  
Author(s):  
R. W. Freel ◽  
M. Hatch ◽  
N. D. Vaziri

The ability of a Cl-secreting epithelium to support net secretion of an anion other than a halide was investigated with 35SO4 flux measurements across the isolated, short-circuited rabbit distal colon. In most experiments, 36Cl fluxes were simultaneously measured to validate the secretory capacity of the tissues. Serosal addition of dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP, 0.5 mM) stimulated a sustained net secretion of SO4 (about -3.0 nmol.cm-2.h-1 from a 0.20 mM solution) via an increase in the serosal-to-mucosal unidirectional flux, whereas Ca ionophore A-23187 (1 microM, serosal) produced a more transient stimulation of SO4 and Cl secretion. Net adenosine 3',5'-cyclic monophosphate (cAMP)-dependent SO4 and Cl secretion were strongly voltage sensitive, principally through the potential dependence of the serosal-to-mucosal fluxes, indicating an electrogenic transport process. Symmetrical replacement of either Na, K, or Cl inhibited cAMP-dependent SO4 secretion, whereas HCO3-free buffers had no effect on SO4 secretion. Serosal bumetanide (50 microM) or furosemide (100 microM) reduced DBcAMP-stimulated SO4 and Cl secretion, whereas serosal 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid or 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (50 microM) blocked DBcAMP-induced SO4 secretion while enhancing net Cl secretion and short-circuit current. Mucosal 5-nitro-2-(3-phenylpropylamino)benzoic acid partially inhibited SO4 secretion and completely inhibited Cl secretion. It is concluded that secretagogue-stimulated SO4 secretion, like Cl secretion, may be an electrogenic process mediated by diffusive efflux through an apical anion conductance. Cellular accumulation of SO4 across the basolateral membrane appears to be achieved by a mechanism that is distinct from that employed by Cl.


1986 ◽  
Vol 250 (4) ◽  
pp. C646-C650 ◽  
Author(s):  
S. R. Shorofsky ◽  
M. Field ◽  
H. A. Fozzard

Na-selective microelectrodes were employed to investigate the mechanism of Cl secretion by canine tracheal epithelium. In control tissues with a mean short-circuit current (Isc) of 30.1 microA/cm2, the intracellular Na activity (aiNa) was 10.7 mM. Following steady-state stimulation of Cl secretion with epinephrine (Isc = 126.4 microA/cm2), aiNa was 21.3 mM. These data indicate that there is sufficient energy in the Na gradient to drive Cl secretion by this tissue. When analyzed with simple kinetic models for the Na-K pump, they also suggest that the basolateral entry step involves the Na-K-2Cl cotransporter.


1984 ◽  
Vol 246 (5) ◽  
pp. R741-R746 ◽  
Author(s):  
S. A. May ◽  
K. J. Degnan

Catecholamine regulation of the Cl- secretion rate (short-circuit current, Isc) and adenosine 3',5'-cyclic monophosphate (cAMP) levels of the opercular epithelium was investigated by using 3-isobutyl-1-methylxanthine (IBMX), forskolin, and adrenergic agonists. In this tissue alpha-adrenergic agonists inhibit, and beta-adrenergic agonists stimulate, the Isc (J. Physiol. London 294: 483-495, 1979). IBMX and forskolin stimulated the Isc 125 and 85%, respectively, and simultaneously produced 2.5- and 70.0-fold elevations in the cAMP levels, respectively. These findings confirm previous observations demonstrating that stimulation of the Isc in this tissue is mediated by elevations in cAMP (J. Comp. Physiol. B 145: 29-35, 1981). Isoproterenol, a beta-agonist, had no effect on the Isc of either IBMX- or forskolin-stimulated tissues but increased the cAMP level an additional 5.8-fold in IBMX-stimulated tissues. Clonidine, an alpha-agonist, inhibited the Isc in IBMX-stimulated tissues only and had no effect on cAMP levels in either IBMX- or forskolin-stimulated tissues. These findings demonstrate that catecholamine-induced inhibition of the Isc can occur while the cAMP level remains elevated, indicating that this effect is not mediated by lowering cAMP levels. This observation is strong evidence for a cAMP-independent mechanism for catecholamine-induced inhibition of Cl- secretion in the opercular and similar epithelia.


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