CFTR, A Regulator of Channels

Kunzelmann, Karl; Schreiber, Rainer

doi:10.1007/s002329900492

Cited by 107 publications

(77 citation statements)

References 101 publications

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“…The secretory anion current, represented by NS-I sc , was partially inhibited by 200 M glibenclamide (Figs. 2 and 3), which is a well-established inhibitor of CFTR at this concentration (33,45). The expression of CFTR protein in FL-MDCK cells was confirmed by RT-PCR and immunoprecipitation experiments (Fig.…”

Section: Discussionmentioning

confidence: 60%

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Inhibition of ENaC by intracellular Cl⁻in an MDCK clone with high ENaC expression

Xie

Schafer

2004

American Journal of Physiology-Renal Physiology

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We examined the effects of intracellular Cl− concentration ([Cl−]i) on the epithelial Na channel (ENaC) in a line of Madin-Darby canine kidney (MDCK) cells (FL-MDCK) with a high rate of Na+ transport produced by stable retroviral transfection with rENaC subunits (Morris RG and Schafer JA. J Gen Physiol 120: 71–85, 2002). Treatment with cAMP (100 μM 8-cpt-cAMP plus 100 μM IBMX) stimulated ENaC-mediated Na+ absorption as well as Cl− secretion via cystic fibrosis transmembrane conductance regulator, which was characterized in α-toxin-permeabilized monolayers to have the anion selectivity sequence NO3− > Br− > Cl− > I−. With the use of FL-MDCK monolayers in which the basolateral membrane was permeabilized by nystatin, the ENaC conductance of the apical membrane [determined from the amiloride-sensitive short-circuit current (AS- Isc) driven by an apical-to-basolateral Na+ concentration gradient] was progressively inhibited by increasing the [Cl−] in the basolateral solution (and hence in the cytosol), but it was insensitive to the [Cl−] in the apical solution. This inhibitory effect of [Cl−]i occurred regardless of the presence or absence of net Cl− transport. However, from fluorometric measurements using the Cl−-sensitive dye 6-methoxy- N-(3-sulfopropyl)-quinolinium in intact FL-MDCK monolayers on permeable supports, cAMP, which activates both Na+ absorption and Cl− secretion, produced a decrease of [Cl−]i from 76 ± 14 to 36 ± 8 mM ( P = 0.03). Thus it might be expected that activation of Cl− secretion by cAMP would lead to stimulation rather than inhibition of ENaC. In the nystatin-treated monolayers, an increase in [Cl−]i from 15 to 145 mM decreased AS- Isc from 24.5 ± 1.0 to 10.2 ± 1.6 μA/cm2. This inhibition of ENaC could be attributed to nearly proportional decreases in the density of ENaC in the apical membrane from 1.91 ± 0.16 to 1.32 ± 0.17 fmol/cm2 and in the intrinsic channel activity (the average current per ENaC subunit) from 13.3 ± 1.2 to 8.2 ± 1.4 μA/fmol.

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Section: Discussionmentioning

confidence: 60%

“…The inhibitory effects of CFTR on Na ϩ transport are also observed in other organs affected by this disease and in a variety of epithelia that express both transporters (21,27,33,45). Several potential mechanisms by which CFTR inhibits ENaC have been proposed.…”

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confidence: 99%

Inhibition of ENaC by intracellular Cl⁻in an MDCK clone with high ENaC expression

Xie

Schafer

2004

American Journal of Physiology-Renal Physiology

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“…6) Genistein blocked the amiloridesensitive depolarization induced by external Na ϩ addition. CFTR is regarded as a global regulator of electrolyte transport through its ability to function as a Cl Ϫ channel (9,46 Garcia and Meizel (28) are approximate. They are averages of a heterogeneous sperm population and were obtained using dyespecific calibration protocols, which assume that dye behavior is the same in different cell types and experimental conditions (24 -26).…”

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confidence: 99%

Involvement of Cystic Fibrosis Transmembrane Conductance Regulator in Mouse Sperm Capacitation

Hernández‐González

Treviño

Castellano

et al. 2007

Journal of Biological Chemistry

149

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Mammalian sperm acquire fertilizing ability in the female tract during a process known as capacitation. In mouse sperm, this process is associated with increases in protein tyrosine phosphorylation, membrane potential hyperpolarization, increase in intracellular pH and Ca 2؉, and hyperactivated motility. The molecular mechanisms involved in these changes are not fully known. Present evidence suggests that in mouse sperm the capacitation-associated membrane hyperpolarization is regulated by a cAMP/protein kinase A-dependent pathway involving activation of inwardly rectifying K ؉ channels and inhibition of epithelial sodium channels (ENaCs). The cystic fibrosis transmembrane conductance regulator (CFTR) is a Cl ؊ channel that controls the activity of several transport proteins, including ENaCs. Here we explored whether CFTR is involved in the regulation of ENaC inhibition in sperm and therefore is essential for the capacitation-associated hyperpolarization. Using reverse transcription-PCR, Western blot, and immunocytochemistry, we document the presence of CFTR in mouse and human sperm. Interestingly, the addition of a CFTR inhibitor (diphenylamine-2-carboxylic acid; 250 M) inhibited the capacitation-associated hyperpolarization, prevented ENaC closure, and decreased the zona pellucida-induced acrosome reaction without affecting the increase in tyrosine phosphorylation. Incubation of sperm in Cl ؊ -free medium also eliminated the capacitationassociated hyperpolarization. On the other hand, a CFTR activator (genistein; 5-10 M) promoted hyperpolarization in mouse sperm incubated under conditions that do not support capacitation. The addition of dibutyryl cyclic AMP to noncapacitated mouse sperm elevated intracellular Cl ؊ . These results suggest that cAMPdependent Cl ؊ fluxes through CFTR are involved in the regulation of ENaC during capacitation and thus contribute to the observed hyperpolarization associated with this process.

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“…The cystic fibrosis transmembrane conductance regulator protein (CFTR) 1 is a cAMP-regulated Cl Ϫ channel that facilitates transepithelial Cl Ϫ transport in the airways, intestine, pancreas, testis, and other tissues. The lethal genetic disease cystic fibrosis is caused by mutations in CFTR.…”

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confidence: 99%

Increased Diffusional Mobility of CFTR at the Plasma Membrane after Deletion of Its C-terminal PDZ Binding Motif

Haggie

Stanton

Verkman

2004

Journal of Biological Chemistry

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The cystic fibrosis transmembrane conductance regulator (CFTR) protein is a cAMP-regulated Cl؊ channel expressed at the apical plasma membrane. It has been proposed that the C-terminal PDZ binding motif of CFTR is required for its apical membrane targeting and that PDZ-domain interactions may tether CFTR to the actin cytoskeleton via soluble proteins including EBP50/ NHERF1 and ezrin. We measured the diffusional mobility of human CFTR in the plasma membrane of Madin- ؊7 cm 2 /s. EBP50 diffusion increased by ϳ2-fold after deletion of its ezrin-binding domain. These results indicate that wild-type CFTR is not tethered statically at the plasma membrane but that its diffusion is dependent on PDZ-domain interactions and an intact actin skeleton. PDZ-domain interactions of CFTR are thus dynamic and occur on a time scale of seconds or faster.

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CFTR, A Regulator of Channels

Cited by 107 publications

References 101 publications

Inhibition of ENaC by intracellular Cl⁻in an MDCK clone with high ENaC expression

Inhibition of ENaC by intracellular Cl⁻in an MDCK clone with high ENaC expression

Involvement of Cystic Fibrosis Transmembrane Conductance Regulator in Mouse Sperm Capacitation

Increased Diffusional Mobility of CFTR at the Plasma Membrane after Deletion of Its C-terminal PDZ Binding Motif

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CFTR, A Regulator of Channels

Cited by 107 publications

References 101 publications

Inhibition of ENaC by intracellular Cl−in an MDCK clone with high ENaC expression

Inhibition of ENaC by intracellular Cl−in an MDCK clone with high ENaC expression

Involvement of Cystic Fibrosis Transmembrane Conductance Regulator in Mouse Sperm Capacitation

Increased Diffusional Mobility of CFTR at the Plasma Membrane after Deletion of Its C-terminal PDZ Binding Motif

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Inhibition of ENaC by intracellular Cl⁻in an MDCK clone with high ENaC expression

Inhibition of ENaC by intracellular Cl⁻in an MDCK clone with high ENaC expression