Lubiprostone is a Non-Selective Activator of cAMP-Gated Ion Channels and Chloride Channel Protein 2 (Clc-2) Has a Minor Role in its Prosecretory Effect in Intestinal Epithelial Cells

Oak, Apurva A; Chu, Tifany; Yottasan, Pattareeya; Chhetri, Parth D; Zhu, J.; Bois, J. Du; Çil, Onur

doi:10.1124/molpharm.122.000542

Cited by 10 publications

(6 citation statements)

References 46 publications

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“…cAMP-induced secretory I sc in intestinal epithelial cells involves the coordinated action of the apical membrane CFTR Cl – channel and basolateral membrane K + channels ( 28 ). To selectively investigate the effect of Mg 2+ on apical CFTR conductance, we conducted experiments using T84 cells with selective basolateral membrane permeabilization and a basolateral-to-apical Cl – gradient ( 29 , 30 ). Under these conditions, addition of 10 mM Mg 2+ to the bathing solution inhibited forskolin and CFTR inh -172–induced I sc changes by 70% ( Figure 4, A and B ).…”

Section: Resultsmentioning

confidence: 99%

“…Under these conditions, addition of 10 mM Mg 2+ to the bathing solution inhibited forskolin and CFTR inh -172–induced I sc changes by 70% ( Figure 4, A and B ). To study the effect of Mg 2+ on basolateral membrane K + channels, we performed experiments with selective apical membrane permeabilization and an apical-to-basolateral K + gradient ( 29 , 31 ). In this setting, addition of 10 mM Mg 2+ to the bathing solution largely reduced basolateral membrane K + conductance, as shown by an 80% reduction in I sc changes in response to forskolin and BaCl 2 (cAMP-activated K + channel inhibitor) ( Figure 4, C and D ).…”

Section: Resultsmentioning

confidence: 99%

“…T84 cells (ATCC CCL–248, human colon carcinoma cells) were cultured as previously described ( 18 , 29 ) on inserts (12 mm diameter, 0.4 μm pore size; Corning Life Sciences) and used for I sc experiments 7 days after plating. FRT cells stably expressing human WT CFTR (FRT-CFTR cells) were cultured as described previously ( 50 ) on inserts and used for I sc experiments 5 days after plating.…”

Section: Methodsmentioning

confidence: 99%

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Mg2+ supplementation treats secretory diarrhea in mice by activating calcium-sensing receptor in intestinal epithelial cells

de Souza Goncalves,

Chu,

Master

et al. 2024

Journal of Clinical Investigation

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Cholera is a global health problem with no targeted therapies. The Ca 2+ -sensing receptor (CaSR) is a regulator of intestinal ion transport and a therapeutic target for diarrhea, and Ca 2+ is considered its main agonist. We found that increasing extracellular Ca 2+ had a minimal effect on forskolin-induced Cl – secretion in human intestinal epithelial T84 cells. However, extracellular Mg 2+ , an often-neglected CaSR agonist, suppressed forskolin-induced Cl – secretion in T84 cells by 65% at physiological levels seen in stool (10 mM). The effect of Mg 2+ occurred via the CaSR/Gq signaling that led to cAMP hydrolysis. Mg 2+ (10 mM) also suppressed Cl- secretion induced by cholera toxin, heat-stable E . coli enterotoxin, and vasoactive intestinal peptide by 50%. In mouse intestinal closed loops, luminal Mg 2+ treatment (20 mM) inhibited cholera toxin–induced fluid accumulation by 40%. In a mouse intestinal perfusion model of cholera, addition of 10 mM Mg 2+ to the perfusate reversed net fluid transport from secretion to absorption. These results suggest that Mg 2+ is the key CaSR activator in mouse and human intestinal epithelia at physiological levels in stool. Since stool Mg 2+ concentrations in patients with cholera are essentially zero, oral Mg 2+ supplementation, alone or in an oral rehydration solution, could be a potential therapy for cholera and other cyclic nucleotide–mediated secretory diarrheas.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Mg2+ supplementation treats secretory diarrhea in mice by activating calcium-sensing receptor in intestinal epithelial cells

de Souza Goncalves,

Chu,

Master

et al. 2024

Journal of Clinical Investigation

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“…Besides CFTR [ 32 ] and also TMEM16A [ 33 ], it has been described that cAMP can modulate the activity of other ion channels and transporters. For instance, cAMP agonists activate the Cl − channel CLCN2 [ 34 ], SLC26A9 [ 35 ], the Cl − /HCO 3 − exchanger pendrin (SLC26A4) [ 36 ], the Na + /HCO 3 − cotransporter NBCE1 [ 37 ] and the H + /K + ATPase HKA2 (ATP12A) [ 29 , 38 ]. Additionally, it has been shown that cAMP modulates the expression of the Cl − /HCO 3 − exchanger type 2 (AE2 or SLC4A2) in airway epithelial cells [ 29 , 39 , 40 ].…”

Section: Discussionmentioning

confidence: 99%

Drug Repurposing for Cystic Fibrosis: Identification of Drugs That Induce CFTR-Independent Fluid Secretion in Nasal Organoids

Rodenburg

Delpiano

Railean

et al. 2022

IJMS

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Individuals with cystic fibrosis (CF) suffer from severe respiratory disease due to a genetic defect in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which impairs airway epithelial ion and fluid secretion. New CFTR modulators that restore mutant CFTR function have been recently approved for a large group of people with CF (pwCF), but ~19% of pwCF cannot benefit from CFTR modulators Restoration of epithelial fluid secretion through non-CFTR pathways might be an effective treatment for all pwCF. Here, we developed a medium-throughput 384-well screening assay using nasal CF airway epithelial organoids, with the aim to repurpose FDA-approved drugs as modulators of non-CFTR-dependent epithelial fluid secretion. From a ~1400 FDA-approved drug library, we identified and validated 12 FDA-approved drugs that induced CFTR-independent fluid secretion. Among the hits were several cAMP-mediating drugs, including β2-adrenergic agonists. The hits displayed no effects on chloride conductance measured in the Ussing chamber, and fluid secretion was not affected by TMEM16A, as demonstrated by knockout (KO) experiments in primary nasal epithelial cells. Altogether, our results demonstrate the use of primary nasal airway cells for medium-scale drug screening, target validation with a highly efficient protocol for generating CRISPR-Cas9 KO cells and identification of compounds which induce fluid secretion in a CFTR- and TMEM16A-indepent manner.

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“…NHE8, a Na + /H + exchanger expressed on the basolateral membrane, is suggested to play a role in tear production and ocular epithelial protection [ 19 ]. Clc-2, a non-CFTR cAMP-activated chloride channel expressed on the apical membrane, may play a similar chloride secretory role to CFTR in many tissues, including the eye [ 20 ]. ASIC, a voltage-insensitive acid-sensing cation (mainly sodium) channel, is implicated in increasing tear and blinking rates and reducing ocular neuropathic pain [ 8•• ].…”

Section: Ocular Surface Ion Transportersmentioning

confidence: 99%

Ocular Surface Ion Transport and Dry Eye Disease

Lindgren

Çil

Pasricha

2022

Curr Ophthalmol Rep

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Purpose of Review To review the role of ocular surface epithelial (corneal and conjunctival) ion transporters in the pathogenesis and treatment of dry eye disease (DED). Recent Findings Currently, anti-inflammatory agents are the mainstay of DED treatment, though there are several agents in development that target ion transport proteins on the ocular surface, acting by pro-secretory or anti-absorptive mechanisms to increase the tear fluid film volume. Activation or inhibition of selected ion transporters can alter tear fluid osmolality, driving water transport onto the ocular surface via osmosis. Several ion transporters have been proposed as potential therapeutic targets for DED, including the cystic fibrosis transmembrane conductance regulator (CFTR), calcium-activated chloride channels (CaCCs), and the epithelial sodium channel (ENaC). Summary Ocular surface epithelial cell ion transporters are promising targets for pro-secretory and anti-absorptive therapies of DED.

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Lubiprostone is a Non-Selective Activator of cAMP-Gated Ion Channels and Chloride Channel Protein 2 (Clc-2) Has a Minor Role in its Prosecretory Effect in Intestinal Epithelial Cells

Cited by 10 publications

References 46 publications

Mg2+ supplementation treats secretory diarrhea in mice by activating calcium-sensing receptor in intestinal epithelial cells

Mg2+ supplementation treats secretory diarrhea in mice by activating calcium-sensing receptor in intestinal epithelial cells

Drug Repurposing for Cystic Fibrosis: Identification of Drugs That Induce CFTR-Independent Fluid Secretion in Nasal Organoids

Ocular Surface Ion Transport and Dry Eye Disease

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