scholarly journals An SH3 binding region in the epithelial Na+ channel (alpha rENaC) mediates its localization at the apical membrane.

1994 ◽  
Vol 13 (19) ◽  
pp. 4440-4450 ◽  
Author(s):  
D. Rotin ◽  
D. Bar-Sagi ◽  
H. O'Brodovich ◽  
J. Merilainen ◽  
V.P. Lehto ◽  
...  
Keyword(s):  
Apical Membrane ◽  
Na Channel ◽  
Binding Region ◽  
Epithelial Na Channel

scholarly journals Interactive Actions of Aldosterone and Insulin on Epithelial Na+ Channel Trafficking

2020 ◽  
Vol 21 (10) ◽  
pp. 3407 ◽  
Author(s):  
Rie Marunaka ◽  
Yoshinori Marunaka
Keyword(s):  
Blood Pressure ◽  
Inhibitory Action ◽  
Apical Membrane ◽  
Short Circuit ◽  
Recycling Rate ◽  
Na Channel ◽  
Stimulatory Action ◽  
Channel Trafficking ◽  
Short Circuit Currents ◽  
Epithelial Na Channel

Epithelial Na+ channel (ENaC) participates in renal epithelial Na+ reabsorption, controlling blood pressure. Aldosterone and insulin elevate blood pressure by increasing the ENaC-mediated Na+ reabsorption. However, little information is available on the interactive action of aldosterone and insulin on the ENaC-mediated Na+ reabsorption. In the present study, we tried to clarify if insulin would modify the aldosterone action on the ENaC-mediated Na+ reabsorption from a viewpoint of intracellular ENaC trafficking. We measured the ENaC-mediated Na+ transport as short-circuit currents using a four-state mathematical ENaC trafficking model in renal A6 epithelial cells with or without aldosterone treatment under the insulin-stimulated and -unstimulated conditions. We found that: (A) under the insulin-stimulated condition, aldosterone treatment (1 µM for 20 h) significantly elevated the ENaC insertion rate to the apical membrane ( k I ) 3.3-fold and the ENaC recycling rate ( k R ) 2.0-fold, but diminished the ENaC degradation rate ( k D ) 0.7-fold without any significant effect on the ENaC endocytotic rate ( k E ); (B) under the insulin-unstimulated condition, aldosterone treatment decreased k E 0.5-fold and increased k R 1.4-fold, without any significant effect on k I or k D . Thus, the present study indicates that: (1) insulin masks the well-known inhibitory action of aldosterone on the ENaC endocytotic rate; (2) insulin induces a stimulatory action of aldosterone on ENaC apical insertion and an inhibitory action of aldosterone on ENaC degradation; (3) insulin enhances the aldosterone action on ENaC recycling; (4) insulin has a more effective action on diminution of ENaC endocytosis than aldosterone.

What Is New About the Structure of the Epithelial Na+ Channel ?

Physiology ◽  
1996 ◽  
Vol 11 (5) ◽  
pp. 195-201
Author(s):  
CM Canessa
Keyword(s):  
Ion Channels ◽  
Apical Membrane ◽  
Na Channel ◽  
Full Activity ◽  
New Family ◽  
Epithelial Na Channel ◽  
Tight Epithelium

The epithelial Na+ channel (ENaC) in the apical membrane of tight epithelium represents the first member of a new family of ion channels. The channel is formed by the association of three homologous subunits, a-, b-, and g-ENaC, that functionally complement to give full activity to the channel complex.

scholarly journals Membrane trafficking pathways regulating the epithelial Na+ channel

2020 ◽  
Vol 318 (1) ◽  
pp. F1-F13 ◽  
Author(s):  
Adam W. Ware ◽  
Sahib R. Rasulov ◽  
Tanya T. Cheung ◽  
J. Shaun Lott ◽  
Fiona J McDonald
Keyword(s):  
Cell Surface ◽  
Blood Volume ◽  
Membrane Trafficking ◽  
Apical Membrane ◽  
Na Channel ◽  
Membrane Domain ◽  
Multiple Forms ◽  
Epithelial Na Channel

Renal Na+ reabsorption, facilitated by the epithelial Na+ channel (ENaC), is subject to multiple forms of control to ensure optimal body blood volume and pressure through altering both the ENaC population and activity at the cell surface. Here, the focus is on regulating the number of ENaCs present in the apical membrane domain through pathways of ENaC synthesis and targeting to the apical membrane as well as ENaC removal, recycling, and degradation. Finally, the mechanisms by which ENaC trafficking pathways are regulated are summarized.

Single-channel behavior of a purified epithelial Na+ channel subunit that binds amiloride

1992 ◽  
Vol 263 (5) ◽  
pp. C1111-C1117 ◽  
Author(s):  
S. Sariban-Sohraby ◽  
M. Abramow ◽  
R. S. Fisher
Keyword(s):  
Single Channel ◽  
Apical Membrane ◽  
Na Channel ◽  
Na Transport ◽  
Patch Clamp Technique ◽  
Transport Inhibitor ◽  
Open Time ◽  
The Mean ◽  
Epithelial Na Channel ◽  
Binding Subunit

The apical membrane of high electrical resistance epithelia, which is selectively permeable to Na+, plays an essential role in the maintenance of salt balance. Na+ entry from the apical fluid into the cells is mediated by amiloride-blockable Na(+)-specific channels. The channel protein, purified from both amphibian and mammalian sources, is composed of several subunits, only one of which the 150-kDa polypeptide, specifically binds the Na+ transport inhibitor amiloride. The goal of the present study was to investigate whether the isolated amiloride-binding subunit of the channel could conduct Na+. The patch-clamp technique was used to study the 150-kDa polypeptide incorporated into a lipid bilayer formed on the tip of a glass pipette. Unitary conductance jumps averaged 4.8 pS at 100 mM Na2HPO4. Open times ranged from 24 ms to several seconds. The channel spent most of the time in the closed state. Channel conductance and gating were independent of voltage between -60 and +100 mV. Amiloride (0.1 microM) decreased the mean open time of the channel by 98%. We conclude that the 150-kDa subunit of the amiloride-blockable Na+ channel conducts current and may be sufficient for the Na+ transport function of the whole channel.

scholarly journals Vacuolar H+-ATPase and Na+/K+-ATPase energize Na+ uptake mechanisms in the nuchal organ of the hyperregulating freshwater crustacean Daphnia magna.

2021 ◽  
Author(s):  
Carolyn Morris ◽  
Michael J. O'Donnell
Keyword(s):  
Daphnia Magna ◽  
Channel Blocker ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Na Channel ◽  
Freshwater Crustacean ◽  
A Site ◽  
Electrode Technique ◽  
Na Uptake ◽  
Epithelial Na Channel

The nuchal organ of the embryos and neonates of the cladoceran, Daphnia magna, has been shown to be a site of Na+ influx and H+, NH4+ and Cl− efflux. This study combines the scanning-ion selective electrode technique with application of inhibitors of specific transporters to assess the mechanisms of Na+ transport across the nuchal organ. Na+ influx across the nuchal organ was inhibited both by inhibitors of the Na+/K+-ATPase (ouabain, bufalin) and by inhibitors of the vacuolar H+-ATPase (bafilomycin, N-ethylmaleimde, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, KM91104, S-nitrosoglutathione). Na+ influx was unaffected by the epithelial Na+ channel blocker benzamil, but was sensitive to ethylisopropyl amiloride and elevated external ammonium concentrations, consistent with roles for Na+/H+ and Na+/NH4+ exchangers in the apical membrane but not Na+ channels. Transport across the basolateral membrane into the hemolymph is proposed to involve the Na+/K+-ATPase and a thiazide-sensitive Na+:Cl− cotransporter. Keywords: Daphnia magna, Na+/K+-ATPase, V-ATPase, Iionoregulation, Nnuchal organ

scholarly journals Differential Effects of Protein Kinase C on the Levels of Epithelial Na+Channel Subunit Proteins

2000 ◽  
Vol 275 (33) ◽  
pp. 25760-25765 ◽  
Author(s):  
James D. Stockand ◽  
Hui-Fang Bao ◽  
Julie Schenck ◽  
Bela Malik ◽  
Pam Middleton ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Na Channel ◽  
Differential Effects ◽  
Kinase C ◽  
Epithelial Na Channel

scholarly journals CRISPR/Cas9 Mediated Knock Down of δ-ENaC Blunted the TNF-Induced Activation of ENaC in A549 Cells

2021 ◽  
Vol 22 (4) ◽  
pp. 1858
Author(s):  
Waheed Shabbir ◽  
Nermina Topcagic ◽  
Mohammed Aufy ◽  
Murat Oz
Keyword(s):  
A549 Cells ◽  
Na Channel ◽  
Na Current ◽  
Patch Clamp Technique ◽  
Whole Cell ◽  
Knock Down ◽  
Whole Cell Patch Clamp ◽  
Glycosylation Sites ◽  
Epithelial Na Channel

Tumor necrosis factor (TNF) is known to activate the epithelial Na+ channel (ENaC) in A549 cells. A549 cells are widely used model for ENaC research. The role of δ-ENaC subunit in TNF-induced activation has not been studied. In this study we hypothesized that δ-ENaC plays a major role in TNF-induced activation of ENaC channel in A549 cells which are widely used model for ENaC research. We used CRISPR/Cas 9 approach to knock down (KD) the δ-ENaC in A549 cells. Western blot and immunofluorescence assays were performed to analyze efficacy of δ-ENaC protein KD. Whole-cell patch clamp technique was used to analyze the TNF-induced activation of ENaC. Overexpression of wild type δ-ENaC in the δ-ENaC KD of A549 cells restored the TNF-induced activation of whole-cell Na+ current. Neither N-linked glycosylation sites nor carboxyl terminus domain of δ-ENaC was necessary for the TNF-induced activation of whole-cell Na+ current in δ-ENaC KD of A549 cells. Our data demonstrated that in A549 cells the δ-ENaC plays a major role in TNF-induced activation of ENaC.

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