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The vast majority of people with cystic fibrosis (CF) are now eligible for CF transmembrane regulator (CFTR) modulator therapy. The remaining individuals with CF harbor premature termination codons (PTCs) or rare CFTR variants with limited treatment options. Although the clinical modulator response can be reliably predicted using primary airway epithelial cells, primary cells carrying rare CFTR variants are scarce. To overcome this obstacle, cell lines can be created by overexpression of mouse Bmi-1 and human TERT (hTERT). Using this approach, we developed 2 non-CF and 6 CF airway epithelial cell lines, 3 of which were homozygous for the W1282X PTC variant. The Bmi-1/hTERT cell lines recapitulated primary cell morphology and ion transport function. The 2 F508del-CFTR cell lines responded robustly to CFTR modulators, which was mirrored in the parent primary cells and in the cell donors' clinical response. Cereblon E3 ligase modulators targeting eukaryotic release factor 3a (eRF3a) rescued W1282X-CFTR function to approximately 20% of WT levels and, when paired with G418, rescued G542XCFTR function to approximately 50% of WT levels. Intriguingly, eRF3a degraders also diminished epithelial sodium channel (ENaC) function. These studies demonstrate that Bmi-1/hTERT cell lines faithfully mirrored primary cell responses to CFTR modulators and illustrate a therapeutic approach to rescue CFTR nonsense mutations., Introduction Cystic fibrosis (CF) is a life-limiting genetic disease affecting approximately 70,000 people worldwide (1). Severe pathology develops in the lungs, where absent or dysfunctional CF transmembrane regulator (CFTR) protein [...]

BackgroundThe Ca(2+)-activated K(+) channel K(Ca)3.1 is expressed in several structural and inflammatory airway cell types and is proposed to play an important role in the pathophysiology of asthma. The aim of the current study was to determine whether inhibition of K(Ca)3.1 modifies experimental asthma in sheep.Methodology and principal findingsAtopic sheep were administered either 30 mg/kg Senicapoc (ICA-17073), a selective inhibitor of the K(Ca)3.1-channel, or vehicle alone (0.5% methylcellulose) twice daily (orally). Both groups received fortnightly aerosol challenges with house dust mite allergen for fourteen weeks. A separate sheep group received no allergen challenges or drug treatment. In the vehicle-control group, twelve weeks of allergen challenges resulted in a 60±19% increase in resting airway resistance, and this was completely attenuated by treatment with Senicapoc (0.25±12%; n = 10, P = 0.0147). The vehicle-control group had a peak-early phase increase in lung resistance of 82±21%, and this was reduced by 58% with Senicapoc treatment (24±14%; n = 10, P = 0.0288). Senicapoc-treated sheep also demonstrated reduced airway hyperresponsiveness, requiring a significantly higher dose of carbachol to increase resistance by 100% compared to allergen-challenged vehicle-control sheep (20±5 vs. 52±18 breath-units of carbachol; n = 10, P = 0.0340). Senicapoc also significantly reduced eosinophil numbers in bronchoalveolar lavage taken 48 hours post-allergen challenge, and reduced vascular remodelling.ConclusionsThese findings suggest that K(Ca)3.1-activity contributes to allergen-induced airway responses, inflammation and vascular remodelling in a sheep model of asthma, and that inhibition of K(Ca)3.1 may be an effective strategy for blocking allergen-induced airway inflammation and hyperresponsiveness in humans.

There are many web sites that provide access to gene sequences. A table of sites is included, focusing on ion channel genes, in particular the potassium channel.

Background and Purpose: TREK two-pore-domain potassium (K2P ) channels play a critical role in regulating the excitability of somatosensory nociceptive neurons and are important mediators of pain perception. An understanding of the roles of TREK channels in pain perception and, indeed, in other pathophysiological conditions, has been severely hampered by the lack of potent and/or selective activators and inhibitors. In this study, we describe a new, selective opener of TREK channels, GI-530159.Experimental Approach: The effect of GI-530159 on TREK channels was demonstrated using 86 Rb efflux assays, whole-cell and single-channel patch-clamp recordings from recombinant TREK channels. The expression of K2P 2.1 (TREK1), K2P 10.1 (TREK2) and K2P 4.1 (TRAAK) channels was determined using transcriptome analysis from single dorsal root ganglion (DRG) cells. Current-clamp recordings from cultured rat DRG neurons were used to measure the effect of GI-530159 on neuronal excitability.Key Results: For recombinant human TREK1 channels, GI-530159 had similar low EC50 values in Rb efflux experiments and electrophysiological recordings. It activated TREK2 channels, but it had no detectable action on TRAAK channels nor any significant effect on other K channels tested. Current-clamp recordings from cultured rat DRG neurones showed that application of GI-530159 at 1 μM resulted in a significant reduction in firing frequency and a small hyperpolarization of resting membrane potential.Conclusions and Implications: This study provides pharmacological evidence for the presence of mechanosensitive TREK K2P channels in sensory neurones and suggests that development of selective K2P channel openers like GI-530159 could aid in the development of novel analgesic agents.Linked Articles: This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc. [ABSTRACT FROM AUTHOR]

Background: The Ca2+-activated K+ channel KCa3.1 is expressed in several structural and inflammatory airway cell types and is proposed to play an important role in the pathophysiology of asthma. The aim of the current study was to determine whether inhibition of KCa3.1 modifies experimental asthma in sheep. Methodology and Principal Findings: Atopic sheep were administered either 30 mg/kg Senicapoc (ICA-17073), a selective inhibitor of the KCa3.1-channel, or vehicle alone (0.5% methylcellulose) twice daily (orally). Both groups received fortnightly aerosol challenges with house dust mite allergen for fourteen weeks. A separate sheep group received no allergen challenges or drug treatment. In the vehicle-control group, twelve weeks of allergen challenges resulted in a 60±19% increase in resting airway resistance, and this was completely attenuated by treatment with Senicapoc (0.25±12%; n = 10, P = 0.0147). The vehicle-control group had a peak-early phase increase in lung resistance of 82±21%, and this was reduced by 58% with Senicapoc treatment (24±14%; n = 10, P = 0.0288). Senicapoc-treated sheep also demonstrated reduced airway hyperresponsiveness, requiring a significantly higher dose of carbachol to increase resistance by 100% compared to allergen-challenged vehicle-control sheep (20±5 vs. 52±18 breath-units of carbachol; n = 10, P = 0.0340). Senicapoc also significantly reduced eosinophil numbers in bronchoalveolar lavage taken 48 hours post-allergen challenge, and reduced vascular remodelling. Conclusions: These findings suggest that KCa3.1-activity contributes to allergen-induced airway responses, inflammation and vascular remodelling in a sheep model of asthma, and that inhibition of KCa3.1 may be an effective strategy for blocking allergen-induced airway inflammation and hyperresponsiveness in humans. [ABSTRACT FROM AUTHOR]

1. Openers of ATP-sensitive K+ channels are of interest in several therapeutic indications including overactive bladder and other lower urinary tract disorders. This study reports on the in vitro and in vivo characterization of a structurally novel naphylamide N-[2-(2,2,2-trifuoro-1-hydroxy-1-trifluoromethyl-ehtyl)-naphtalen-1-yl]-acetaide (A-151892), as an opener of the ATP-sensitive potassium channels. 2. A-151892 was found to be a potent a efficacious potassium channel opener (KCO) as assessed by glibenclamide-sensitive whole-cell current and fluorescence-based membrane potential responses (-log EC59=7.63) in guinea-pig bladder smooth muscle cells. 3. Evidence for direct interaction with KCO binding sites was derived from displacement of binding of the 1.4-dihydropyridine opener [125I]A-312110. A-151892 displace [125I]A-312110 binding o bladder membranes with a -log Ki value of 7.45, but lacked against over 70 neurotransmitter receptor and ion channel binding sites. 4. In pig bladder strips, A-151892 suppressed plastic, carbachol-evoked and electrical field stimulus-evoked contractility in a glibenclamide-reversible manner with -log IC50 values of 8.07, 7.33 and 7.02 respectively, comparable to that of th potencies of the prototypical eyanoguanidine KCO, P1075. The potencies to suppress contractions in thoracic aorta (-log IC50 = 7.81) and portal vein (-log IC50 = 7.98) were not substabtially different from those observed for suppression of phasic contrctility of the bladder smooth muscle. 5. In vivo, A-151892 was found to potently suppress unstable bladder contraction in obstructed models of unstable contractions in both pigs and rats with pED35% values of 8.05 and 7.43, respectively. 6. These results demonstrate that napthylamide analogs exemplified by A-151892 are novel KATP channel openers and may serve as chemotypes to exploit additional analogs with potential for the treatment of overactive bladder and lowe urinary tract symptoms. [ABSTRACT FROM AUTHOR]

Objective: The aim was to characterise the development of the transient outward current (Ito) in atrial myocytes of infants and children. Methods: Whole cell voltage clamp was used to study outward currents in enzymatically isolated atrial myocytes from infants and children ranging in age from 3 days to 13.2 years. Results: A transient inactivating current characteristic of Ito was observed in 71 myocytes from 22 patients aged 3 days to 13.2 years, including a 10 day old infant born prematurely at 33 weeks gestation. There was no discernible developmental trend in Ito current density [10.74(SEM 0.65) pA·pF−1 at +40 mV, n = 71 cells from 22 patients] or voltage dependence of inactivation, newborn values being similar to those in older children, and in adults reported elsewhere. A developmental reduction in total outward current density was attributable entirely to diminution of the non-inactivating steady state current component. The Ito time course of inactivation showed an apparent maturational evolution, with the youngest infants having slightly but significantly slower inactivation kinetics. The kinetics of Ito recovery from inactivation were well described by a single exponential model with no appreciable developmental trend in time course. Conclusions: Ito is expressed in human atrial myocytes from early infancy and does not show significant developmental changes in current density. The relative contribution of Ito to myocyte repolarisation might increase with age as a result of diminution in the non-inactivating current component. There is an apparent slight maturational acceleration in the time course of Ito inactivation but not in recovery from inactivation, perhaps excluding the latter as a mechanism for the previously reported functional unavailability of Ito in young human atrial muscle. [ABSTRACT FROM PUBLISHER]