Role of anion exchangers in Cl− and HCO3− secretion by the human airway epithelial cell line Calu-3

Kim, Dusik; Kim, Juyeon; Burghardt, Beáta; Best, Leonard; Steward, Martin C.

doi:10.1152/ajpcell.00083.2014

Cited by 16 publications

(26 citation statements)

References 63 publications

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“…These data suggest that VIP receptor activation or direct cAMP elevation with forskolin can activate both Cland HCO3secretion directly through CFTR. We found no evidence for Cl -/HCO3exchanger-mediated HCO3efflux in primary serous cells (Supplemental Figure 2), suggesting CFTR is the main HCO3efflux pathway during cAMP stimulation, agreeing with recent Calu-3 studies suggesting CFTR sustains HCO3secretion (88,89) instead of the pendrin Cl -/HCO3exchanger (90,91).…”

Section: Vip Stimulates Both Cland Hco3secretion From Airway Gland Sesupporting

confidence: 89%

Inverse regulation of secretion and inflammation in human airway gland serous cells by neuropeptides upregulated in allergy and asthma

McMahon

Kohanski

Tong

et al. 2019

Preprint

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Airway submucosal gland serous cells are sites of expression of the cystic fibrosis transmembrane conductance regulator (CFTR) and are important for fluid secretion in conducting airways from the nose down to small bronchi. We tested if serous cells from human nasal turbinate glands secrete bicarbonate (HCO3 -), important for mucus polymerization, during stimulation with the cAMP-elevating agonist vasoactive intestinal peptide (VIP) and if this requires CFTR. Isoalted serous cells stimulated with VIP exhibited a ~20% cAMP-dependent decrease in cell volume and a ~0.15 unit decrease in intracellular pH (pHi), reflecting activation of Cland HCO3secretion, respectively.Pharmacology, ion substitution, and studies using cells from CF patients suggest serous cell HCO3secretion is mediated by conductive efflux directly through CFTR. Interestingly, we found that neuropeptide Y (NPY) reduced VIP-evoked secretion by blunting cAMP increases and reducing CFTR activation through Gi-coupled NPY1R. Culture of primary gland serous cells in a model that maintained a serous phenotype confirmed the activating and inhibiting effects of VIP and NPY, respectively, on fluid and HCO3secretion. Moreover, VIP enhanced secretion of antimicrobial peptides and antimicrobial efficacy of gland secretions while NPY reduced antimicrobial secretions. In contrast, NPY enhanced the release of cytokines during inflammatory stimuli while VIP reduced cytokine release through a mechanism requiring CFTR conductance. As levels of VIP and NPY are up-regulated in disease like allergy, asthma, and chronic rhinosinusitis, the balance of these two peptides in the airway may control airway mucus rheology and inflammatory responses through gland serous cells.

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Section: Vip Stimulates Both Cland Hco3secretion From Airway Gland Sesupporting

confidence: 89%

Inverse regulation of secretion and inflammation in human airway gland serous cells by neuropeptides upregulated in allergy and asthma

McMahon

Kohanski

Tong

et al. 2019

Preprint

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“…Our laboratory [ 14 , 15 ] and others [ 24 ] have previously reported that Cl − /HCO 3 − exchange occurs across the basolateral membrane in non-stimulated Calu-3 cells. In support of these findings, intracellular pH measurements showed that removal of basolateral Cl − caused an intracellular alkalinization of 0.36 ± 0.02 units ( n = 8; Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, it has been shown that AE2 is expressed in the airways [ 1 , 12 , 55 ] and immunostaining experiments performed on polarized Calu-3 cells have localized the expression of AE2 to the basolateral membrane [ 32 ]. Our laboratory [ 14 , 15 ] and others [ 24 ] have recently demonstrated that a functional Cl − /HCO 3 − exchanger is present at the basolateral surface of Calu-3 cells under resting conditions, with features consistent with AE2. In addition, Huang et al [ 18 ] showed that intracellular alkalinization produced by basolateral Cl − removal was decreased by 80% in SLC4A2 knockdown Calu-3 cells.…”

Section: Introductionmentioning

confidence: 99%

“…We found that this exchanger was almost completely inhibited by elevations in intracellular cAMP [ 14 , 15 ], which we proposed would enhance cAMP-stimulated transepithelial HCO 3 − secretion, by reducing HCO 3 − export across the basolateral membrane. However, Kim et al [ 24 ] demonstrated that inhibition of CFTR maintained AE2 activity in cAMP-stimulated Calu-3 cells, while Huang et al [ 18 ] suggested that AE2, acting in concert with Na + /HCO 3 − cotransporters, was involved in basolateral Cl − loading and HCO 3 − recycling that helped maintain transepithelial Cl − secretion under cAMP-stimulated conditions in Calu-3 cells. Thus, the role of AE2 in airway HCO 3 − and fluid secretion is still controversial and not fully understood.…”

Section: Introductionmentioning

confidence: 99%

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CK2 is a key regulator of SLC4A2-mediated Cl−/HCO3 − exchange in human airway epithelia

Ibrahim

Turner

Saint‐Criq

et al. 2017

Pflugers Arch - Eur J Physiol

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Transepithelial bicarbonate secretion by human airway submucosal glands and surface epithelial cells is crucial to maintain the pH-sensitive innate defence mechanisms of the lung. cAMP agonists stimulate HCO3 − secretion via coordinated increases in basolateral HCO3 − influx and accumulation, as well as CFTR-dependent HCO3 − efflux at the luminal membrane of airway epithelial cells. Here, we investigated the regulation of a basolateral located, DIDS-sensitive, Cl−/HCO3 − exchanger, anion exchanger 2 (AE2; SLC4A2) which is postulated to act as an acid loader, and therefore potential regulator of HCO3 − secretion, in human airway epithelial cells. Using intracellular pH measurements performed on Calu-3 cells, we demonstrate that the activity of the basolateral Cl−/HCO3 − exchanger was significantly downregulated by cAMP agonists, via a PKA-independent mechanism and also required Ca2+ and calmodulin under resting conditions. AE2 contains potential phosphorylation sites by a calmodulin substrate, protein kinase CK2, and we demonstrated that AE2 activity was reduced in the presence of CK2 inhibition. Moreover, CK2 inhibition abolished the activity of AE2 in primary human nasal epithelia. Studies performed on mouse AE2 transfected into HEK-293T cells confirmed almost identical Ca2+/calmodulin and CK2 regulation to that observed in Calu-3 and primary human nasal cells. Furthermore, mouse AE2 activity was reduced by genetic knockout of CK2, an effect which was rescued by exogenous CK2 expression. Together, these findings are the first to demonstrate that CK2 is a key regulator of Cl−-dependent HCO3 − export at the serosal membrane of human airway epithelial cells.Electronic supplementary materialThe online version of this article (doi:10.1007/s00424-017-1981-3) contains supplementary material, which is available to authorized users.

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“…Intracellular chloride (Cl − ) is the major anion in living cells and plays a crucial role in maintaining cellular functions in many cell types [1][2][3][4][5][6][7][8], such as cell volume [3,6], intracellular pH [9] and fluid secretion [10,11]. MQAE, a fluorescent Cl − indicator, has been found to be a useful fluorescence dye for noninvasive measurements of the intracellular Cl − concentration ([Cl − ] i ) [12][13][14][15][16][17], with a number of advantageous properties.…”

Section: Introductionmentioning

confidence: 99%

Measurement of [Cl−]i unaffected by the cell volume change using MQAE-based two-photon microscopy in airway ciliary cells of mice

et al. 2018

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MQAE is a 'non-ratiometric' chloride ion (Cl)-quenched fluorescent indicator that is used to determine intracellular Cl concentration ([Cl]). MQAE-based two-photon microscopy is reported to be a useful method to measure [Cl], but it is still controversial because a change in cell volume may alter the MQAE concentration, leading to a change in the fluorescence intensity without any change in [Cl]. In an attempt to elucidate the effect or lack of effect of cell volume on MQAE concentration, we studied the effects of changes in cell volume, achieved by applying different levels of osmotic stress, on the intensity of MQAE fluorescence in airway ciliary cells. To study solely the effect of changes in cell volume on MQAE fluorescence intensity, i.e., excluding the effect of any change in [Cl], we first conducted the experiments in a Cl-free nitrate (NO) solution to substitute NO (non-quenching anion for MQAE fluorescence) for Cl in the intracellular fluid. Hypo- (- 30 mM NaNO) or hyper-osmotic stress (+ 30 mM NaNO) effected changes in cell volume, but the stress did not result in any significant change in MQAE fluorescence intensity. The experiments were also carried out in Cl-containing solution. Hypo-osmotic stress (- 30 mM NaCl) increased both MQAE fluorescence intensity and cell volume, while hyper-osmotic stress (+ 30 mM NaCl) decreased both of these properties. These results suggest that the osmotic stress-induced change in MQAE fluorescence intensity was caused by the change in [Cl] and not by the MQAE concentration. Moreover, the intracellular distribution of MQAEs was heterogeneous and not affected by the changes in osmotic stress-induced cell volume, suggesting that MQAEs are bound to un-identified subcellular structures. These bound MQAEs appear to have enabled the measurement of [Cl] in airway ciliary cells, even under conditions of cell volume change.

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Role of anion exchangers in Cl⁻ and HCO₃⁻ secretion by the human airway epithelial cell line Calu-3

Cited by 16 publications

References 63 publications

Inverse regulation of secretion and inflammation in human airway gland serous cells by neuropeptides upregulated in allergy and asthma

Inverse regulation of secretion and inflammation in human airway gland serous cells by neuropeptides upregulated in allergy and asthma

CK2 is a key regulator of SLC4A2-mediated Cl−/HCO3 − exchange in human airway epithelia

Measurement of [Cl−]i unaffected by the cell volume change using MQAE-based two-photon microscopy in airway ciliary cells of mice

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